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c58b209a | 1 | @c Copyright (C) 1988,1989,1992,1993,1994,1995,1996,1997,1998,1999,2000,2001, |
66647d44 JJ |
2 | @c 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009 |
3 | @c Free Software Foundation, Inc. | |
feca2ed3 JW |
4 | @c This is part of the GCC manual. |
5 | @c For copying conditions, see the file gcc.texi. | |
6 | ||
7 | @node Target Macros | |
672a6f42 | 8 | @chapter Target Description Macros and Functions |
feca2ed3 JW |
9 | @cindex machine description macros |
10 | @cindex target description macros | |
11 | @cindex macros, target description | |
12 | @cindex @file{tm.h} macros | |
13 | ||
14 | In addition to the file @file{@var{machine}.md}, a machine description | |
15 | includes a C header file conventionally given the name | |
672a6f42 NB |
16 | @file{@var{machine}.h} and a C source file named @file{@var{machine}.c}. |
17 | The header file defines numerous macros that convey the information | |
18 | about the target machine that does not fit into the scheme of the | |
19 | @file{.md} file. The file @file{tm.h} should be a link to | |
20 | @file{@var{machine}.h}. The header file @file{config.h} includes | |
21 | @file{tm.h} and most compiler source files include @file{config.h}. The | |
648c546a | 22 | source file defines a variable @code{targetm}, which is a structure |
672a6f42 NB |
23 | containing pointers to functions and data relating to the target |
24 | machine. @file{@var{machine}.c} should also contain their definitions, | |
25 | if they are not defined elsewhere in GCC, and other functions called | |
26 | through the macros defined in the @file{.h} file. | |
feca2ed3 JW |
27 | |
28 | @menu | |
648c546a | 29 | * Target Structure:: The @code{targetm} variable. |
feca2ed3 | 30 | * Driver:: Controlling how the driver runs the compilation passes. |
630d3d5a | 31 | * Run-time Target:: Defining @samp{-m} options like @option{-m68000} and @option{-m68020}. |
414c4dc4 | 32 | * Per-Function Data:: Defining data structures for per-function information. |
feca2ed3 JW |
33 | * Storage Layout:: Defining sizes and alignments of data. |
34 | * Type Layout:: Defining sizes and properties of basic user data types. | |
35 | * Registers:: Naming and describing the hardware registers. | |
36 | * Register Classes:: Defining the classes of hardware registers. | |
f38840db | 37 | * Old Constraints:: The old way to define machine-specific constraints. |
feca2ed3 | 38 | * Stack and Calling:: Defining which way the stack grows and by how much. |
6ccde948 | 39 | * Varargs:: Defining the varargs macros. |
feca2ed3 JW |
40 | * Trampolines:: Code set up at run time to enter a nested function. |
41 | * Library Calls:: Controlling how library routines are implicitly called. | |
42 | * Addressing Modes:: Defining addressing modes valid for memory operands. | |
aacd3885 | 43 | * Anchored Addresses:: Defining how @option{-fsection-anchors} should work. |
feca2ed3 JW |
44 | * Condition Code:: Defining how insns update the condition code. |
45 | * Costs:: Defining relative costs of different operations. | |
c237e94a | 46 | * Scheduling:: Adjusting the behavior of the instruction scheduler. |
feca2ed3 | 47 | * Sections:: Dividing storage into text, data, and other sections. |
6ccde948 | 48 | * PIC:: Macros for position independent code. |
feca2ed3 JW |
49 | * Assembler Format:: Defining how to write insns and pseudo-ops to output. |
50 | * Debugging Info:: Defining the format of debugging output. | |
b216cd4a | 51 | * Floating Point:: Handling floating point for cross-compilers. |
9f09b1f2 | 52 | * Mode Switching:: Insertion of mode-switching instructions. |
91d231cb | 53 | * Target Attributes:: Defining target-specific uses of @code{__attribute__}. |
feb60f03 | 54 | * Emulated TLS:: Emulated TLS support. |
d604bca3 | 55 | * MIPS Coprocessors:: MIPS coprocessor support and how to customize it. |
7bb1ad93 | 56 | * PCH Target:: Validity checking for precompiled headers. |
4185ae53 | 57 | * C++ ABI:: Controlling C++ ABI changes. |
feca2ed3 JW |
58 | * Misc:: Everything else. |
59 | @end menu | |
60 | ||
672a6f42 | 61 | @node Target Structure |
648c546a | 62 | @section The Global @code{targetm} Variable |
672a6f42 NB |
63 | @cindex target hooks |
64 | @cindex target functions | |
65 | ||
f6897b10 SS |
66 | @deftypevar {struct gcc_target} targetm |
67 | The target @file{.c} file must define the global @code{targetm} variable | |
672a6f42 NB |
68 | which contains pointers to functions and data relating to the target |
69 | machine. The variable is declared in @file{target.h}; | |
70 | @file{target-def.h} defines the macro @code{TARGET_INITIALIZER} which is | |
71 | used to initialize the variable, and macros for the default initializers | |
72 | for elements of the structure. The @file{.c} file should override those | |
73 | macros for which the default definition is inappropriate. For example: | |
74 | @smallexample | |
75 | #include "target.h" | |
76 | #include "target-def.h" | |
77 | ||
78 | /* @r{Initialize the GCC target structure.} */ | |
79 | ||
91d231cb JM |
80 | #undef TARGET_COMP_TYPE_ATTRIBUTES |
81 | #define TARGET_COMP_TYPE_ATTRIBUTES @var{machine}_comp_type_attributes | |
672a6f42 | 82 | |
f6897b10 | 83 | struct gcc_target targetm = TARGET_INITIALIZER; |
672a6f42 NB |
84 | @end smallexample |
85 | @end deftypevar | |
86 | ||
87 | Where a macro should be defined in the @file{.c} file in this manner to | |
648c546a | 88 | form part of the @code{targetm} structure, it is documented below as a |
672a6f42 NB |
89 | ``Target Hook'' with a prototype. Many macros will change in future |
90 | from being defined in the @file{.h} file to being part of the | |
648c546a | 91 | @code{targetm} structure. |
672a6f42 | 92 | |
feca2ed3 JW |
93 | @node Driver |
94 | @section Controlling the Compilation Driver, @file{gcc} | |
95 | @cindex driver | |
96 | @cindex controlling the compilation driver | |
97 | ||
98 | @c prevent bad page break with this line | |
99 | You can control the compilation driver. | |
100 | ||
a2c4f8e0 | 101 | @defmac SWITCH_TAKES_ARG (@var{char}) |
630d3d5a | 102 | A C expression which determines whether the option @option{-@var{char}} |
feca2ed3 JW |
103 | takes arguments. The value should be the number of arguments that |
104 | option takes--zero, for many options. | |
105 | ||
106 | By default, this macro is defined as | |
107 | @code{DEFAULT_SWITCH_TAKES_ARG}, which handles the standard options | |
108 | properly. You need not define @code{SWITCH_TAKES_ARG} unless you | |
109 | wish to add additional options which take arguments. Any redefinition | |
110 | should call @code{DEFAULT_SWITCH_TAKES_ARG} and then check for | |
111 | additional options. | |
a2c4f8e0 | 112 | @end defmac |
feca2ed3 | 113 | |
a2c4f8e0 | 114 | @defmac WORD_SWITCH_TAKES_ARG (@var{name}) |
630d3d5a | 115 | A C expression which determines whether the option @option{-@var{name}} |
feca2ed3 JW |
116 | takes arguments. The value should be the number of arguments that |
117 | option takes--zero, for many options. This macro rather than | |
118 | @code{SWITCH_TAKES_ARG} is used for multi-character option names. | |
119 | ||
120 | By default, this macro is defined as | |
121 | @code{DEFAULT_WORD_SWITCH_TAKES_ARG}, which handles the standard options | |
122 | properly. You need not define @code{WORD_SWITCH_TAKES_ARG} unless you | |
123 | wish to add additional options which take arguments. Any redefinition | |
124 | should call @code{DEFAULT_WORD_SWITCH_TAKES_ARG} and then check for | |
125 | additional options. | |
a2c4f8e0 | 126 | @end defmac |
feca2ed3 | 127 | |
a2c4f8e0 | 128 | @defmac SWITCH_CURTAILS_COMPILATION (@var{char}) |
630d3d5a | 129 | A C expression which determines whether the option @option{-@var{char}} |
88117d44 | 130 | stops compilation before the generation of an executable. The value is |
df2a54e9 | 131 | boolean, nonzero if the option does stop an executable from being |
88117d44 NC |
132 | generated, zero otherwise. |
133 | ||
134 | By default, this macro is defined as | |
135 | @code{DEFAULT_SWITCH_CURTAILS_COMPILATION}, which handles the standard | |
136 | options properly. You need not define | |
137 | @code{SWITCH_CURTAILS_COMPILATION} unless you wish to add additional | |
138 | options which affect the generation of an executable. Any redefinition | |
139 | should call @code{DEFAULT_SWITCH_CURTAILS_COMPILATION} and then check | |
140 | for additional options. | |
a2c4f8e0 | 141 | @end defmac |
88117d44 | 142 | |
a2c4f8e0 | 143 | @defmac SWITCHES_NEED_SPACES |
feca2ed3 JW |
144 | A string-valued C expression which enumerates the options for which |
145 | the linker needs a space between the option and its argument. | |
146 | ||
147 | If this macro is not defined, the default value is @code{""}. | |
a2c4f8e0 | 148 | @end defmac |
feca2ed3 | 149 | |
a2c4f8e0 | 150 | @defmac TARGET_OPTION_TRANSLATE_TABLE |
0259b07a DD |
151 | If defined, a list of pairs of strings, the first of which is a |
152 | potential command line target to the @file{gcc} driver program, and the | |
153 | second of which is a space-separated (tabs and other whitespace are not | |
154 | supported) list of options with which to replace the first option. The | |
155 | target defining this list is responsible for assuring that the results | |
156 | are valid. Replacement options may not be the @code{--opt} style, they | |
157 | must be the @code{-opt} style. It is the intention of this macro to | |
158 | provide a mechanism for substitution that affects the multilibs chosen, | |
159 | such as one option that enables many options, some of which select | |
4ec7afd7 KH |
160 | multilibs. Example nonsensical definition, where @option{-malt-abi}, |
161 | @option{-EB}, and @option{-mspoo} cause different multilibs to be chosen: | |
0259b07a | 162 | |
478c9e72 | 163 | @smallexample |
0259b07a DD |
164 | #define TARGET_OPTION_TRANSLATE_TABLE \ |
165 | @{ "-fast", "-march=fast-foo -malt-abi -I/usr/fast-foo" @}, \ | |
166 | @{ "-compat", "-EB -malign=4 -mspoo" @} | |
478c9e72 | 167 | @end smallexample |
a2c4f8e0 | 168 | @end defmac |
0259b07a | 169 | |
a2c4f8e0 | 170 | @defmac DRIVER_SELF_SPECS |
db36994b RS |
171 | A list of specs for the driver itself. It should be a suitable |
172 | initializer for an array of strings, with no surrounding braces. | |
173 | ||
3bd6d4c4 AO |
174 | The driver applies these specs to its own command line between loading |
175 | default @file{specs} files (but not command-line specified ones) and | |
176 | choosing the multilib directory or running any subcommands. It | |
177 | applies them in the order given, so each spec can depend on the | |
178 | options added by earlier ones. It is also possible to remove options | |
179 | using @samp{%<@var{option}} in the usual way. | |
db36994b RS |
180 | |
181 | This macro can be useful when a port has several interdependent target | |
182 | options. It provides a way of standardizing the command line so | |
183 | that the other specs are easier to write. | |
184 | ||
185 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 186 | @end defmac |
db36994b | 187 | |
a2c4f8e0 | 188 | @defmac OPTION_DEFAULT_SPECS |
7816bea0 DJ |
189 | A list of specs used to support configure-time default options (i.e.@: |
190 | @option{--with} options) in the driver. It should be a suitable initializer | |
191 | for an array of structures, each containing two strings, without the | |
192 | outermost pair of surrounding braces. | |
193 | ||
194 | The first item in the pair is the name of the default. This must match | |
195 | the code in @file{config.gcc} for the target. The second item is a spec | |
196 | to apply if a default with this name was specified. The string | |
197 | @samp{%(VALUE)} in the spec will be replaced by the value of the default | |
198 | everywhere it occurs. | |
199 | ||
200 | The driver will apply these specs to its own command line between loading | |
201 | default @file{specs} files and processing @code{DRIVER_SELF_SPECS}, using | |
202 | the same mechanism as @code{DRIVER_SELF_SPECS}. | |
203 | ||
204 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 205 | @end defmac |
7816bea0 | 206 | |
a2c4f8e0 | 207 | @defmac CPP_SPEC |
a3a15b4d | 208 | A C string constant that tells the GCC driver program options to |
161d7b59 JM |
209 | pass to CPP@. It can also specify how to translate options you |
210 | give to GCC into options for GCC to pass to the CPP@. | |
feca2ed3 JW |
211 | |
212 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 213 | @end defmac |
feca2ed3 | 214 | |
a2c4f8e0 | 215 | @defmac CPLUSPLUS_CPP_SPEC |
a9374841 | 216 | This macro is just like @code{CPP_SPEC}, but is used for C++, rather |
161d7b59 | 217 | than C@. If you do not define this macro, then the value of |
a9374841 | 218 | @code{CPP_SPEC} (if any) will be used instead. |
a2c4f8e0 | 219 | @end defmac |
a9374841 | 220 | |
a2c4f8e0 | 221 | @defmac CC1_SPEC |
a3a15b4d | 222 | A C string constant that tells the GCC driver program options to |
66519c70 JL |
223 | pass to @code{cc1}, @code{cc1plus}, @code{f771}, and the other language |
224 | front ends. | |
a3a15b4d | 225 | It can also specify how to translate options you give to GCC into options |
630d3d5a | 226 | for GCC to pass to front ends. |
feca2ed3 JW |
227 | |
228 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 229 | @end defmac |
feca2ed3 | 230 | |
a2c4f8e0 | 231 | @defmac CC1PLUS_SPEC |
a3a15b4d | 232 | A C string constant that tells the GCC driver program options to |
feca2ed3 | 233 | pass to @code{cc1plus}. It can also specify how to translate options you |
a3a15b4d | 234 | give to GCC into options for GCC to pass to the @code{cc1plus}. |
feca2ed3 JW |
235 | |
236 | Do not define this macro if it does not need to do anything. | |
1d96e5b4 FF |
237 | Note that everything defined in CC1_SPEC is already passed to |
238 | @code{cc1plus} so there is no need to duplicate the contents of | |
161d7b59 | 239 | CC1_SPEC in CC1PLUS_SPEC@. |
a2c4f8e0 | 240 | @end defmac |
feca2ed3 | 241 | |
a2c4f8e0 | 242 | @defmac ASM_SPEC |
a3a15b4d | 243 | A C string constant that tells the GCC driver program options to |
feca2ed3 | 244 | pass to the assembler. It can also specify how to translate options |
a3a15b4d | 245 | you give to GCC into options for GCC to pass to the assembler. |
feca2ed3 JW |
246 | See the file @file{sun3.h} for an example of this. |
247 | ||
248 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 249 | @end defmac |
feca2ed3 | 250 | |
a2c4f8e0 | 251 | @defmac ASM_FINAL_SPEC |
a3a15b4d | 252 | A C string constant that tells the GCC driver program how to |
feca2ed3 JW |
253 | run any programs which cleanup after the normal assembler. |
254 | Normally, this is not needed. See the file @file{mips.h} for | |
255 | an example of this. | |
256 | ||
257 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 258 | @end defmac |
feca2ed3 | 259 | |
a2c4f8e0 | 260 | @defmac AS_NEEDS_DASH_FOR_PIPED_INPUT |
4977bab6 ZW |
261 | Define this macro, with no value, if the driver should give the assembler |
262 | an argument consisting of a single dash, @option{-}, to instruct it to | |
263 | read from its standard input (which will be a pipe connected to the | |
264 | output of the compiler proper). This argument is given after any | |
265 | @option{-o} option specifying the name of the output file. | |
266 | ||
267 | If you do not define this macro, the assembler is assumed to read its | |
268 | standard input if given no non-option arguments. If your assembler | |
269 | cannot read standard input at all, use a @samp{%@{pipe:%e@}} construct; | |
270 | see @file{mips.h} for instance. | |
a2c4f8e0 | 271 | @end defmac |
4977bab6 | 272 | |
a2c4f8e0 | 273 | @defmac LINK_SPEC |
a3a15b4d | 274 | A C string constant that tells the GCC driver program options to |
feca2ed3 | 275 | pass to the linker. It can also specify how to translate options you |
a3a15b4d | 276 | give to GCC into options for GCC to pass to the linker. |
feca2ed3 JW |
277 | |
278 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 279 | @end defmac |
feca2ed3 | 280 | |
a2c4f8e0 | 281 | @defmac LIB_SPEC |
feca2ed3 JW |
282 | Another C string constant used much like @code{LINK_SPEC}. The difference |
283 | between the two is that @code{LIB_SPEC} is used at the end of the | |
284 | command given to the linker. | |
285 | ||
286 | If this macro is not defined, a default is provided that | |
287 | loads the standard C library from the usual place. See @file{gcc.c}. | |
a2c4f8e0 | 288 | @end defmac |
feca2ed3 | 289 | |
a2c4f8e0 | 290 | @defmac LIBGCC_SPEC |
a3a15b4d | 291 | Another C string constant that tells the GCC driver program |
feca2ed3 JW |
292 | how and when to place a reference to @file{libgcc.a} into the |
293 | linker command line. This constant is placed both before and after | |
294 | the value of @code{LIB_SPEC}. | |
295 | ||
a3a15b4d | 296 | If this macro is not defined, the GCC driver provides a default that |
630d3d5a | 297 | passes the string @option{-lgcc} to the linker. |
a2c4f8e0 | 298 | @end defmac |
feca2ed3 | 299 | |
328163dc MA |
300 | @defmac REAL_LIBGCC_SPEC |
301 | By default, if @code{ENABLE_SHARED_LIBGCC} is defined, the | |
302 | @code{LIBGCC_SPEC} is not directly used by the driver program but is | |
303 | instead modified to refer to different versions of @file{libgcc.a} | |
4ec7afd7 KH |
304 | depending on the values of the command line flags @option{-static}, |
305 | @option{-shared}, @option{-static-libgcc}, and @option{-shared-libgcc}. On | |
328163dc MA |
306 | targets where these modifications are inappropriate, define |
307 | @code{REAL_LIBGCC_SPEC} instead. @code{REAL_LIBGCC_SPEC} tells the | |
308 | driver how to place a reference to @file{libgcc} on the link command | |
309 | line, but, unlike @code{LIBGCC_SPEC}, it is used unmodified. | |
310 | @end defmac | |
311 | ||
743eeb5a AM |
312 | @defmac USE_LD_AS_NEEDED |
313 | A macro that controls the modifications to @code{LIBGCC_SPEC} | |
314 | mentioned in @code{REAL_LIBGCC_SPEC}. If nonzero, a spec will be | |
315 | generated that uses --as-needed and the shared libgcc in place of the | |
316 | static exception handler library, when linking without any of | |
317 | @code{-static}, @code{-static-libgcc}, or @code{-shared-libgcc}. | |
318 | @end defmac | |
319 | ||
320 | @defmac LINK_EH_SPEC | |
321 | If defined, this C string constant is added to @code{LINK_SPEC}. | |
322 | When @code{USE_LD_AS_NEEDED} is zero or undefined, it also affects | |
323 | the modifications to @code{LIBGCC_SPEC} mentioned in | |
324 | @code{REAL_LIBGCC_SPEC}. | |
325 | @end defmac | |
326 | ||
a2c4f8e0 | 327 | @defmac STARTFILE_SPEC |
feca2ed3 JW |
328 | Another C string constant used much like @code{LINK_SPEC}. The |
329 | difference between the two is that @code{STARTFILE_SPEC} is used at | |
330 | the very beginning of the command given to the linker. | |
331 | ||
332 | If this macro is not defined, a default is provided that loads the | |
333 | standard C startup file from the usual place. See @file{gcc.c}. | |
a2c4f8e0 | 334 | @end defmac |
feca2ed3 | 335 | |
a2c4f8e0 | 336 | @defmac ENDFILE_SPEC |
feca2ed3 JW |
337 | Another C string constant used much like @code{LINK_SPEC}. The |
338 | difference between the two is that @code{ENDFILE_SPEC} is used at | |
339 | the very end of the command given to the linker. | |
340 | ||
341 | Do not define this macro if it does not need to do anything. | |
a2c4f8e0 | 342 | @end defmac |
feca2ed3 | 343 | |
a2c4f8e0 | 344 | @defmac THREAD_MODEL_SPEC |
008355a6 AO |
345 | GCC @code{-v} will print the thread model GCC was configured to use. |
346 | However, this doesn't work on platforms that are multilibbed on thread | |
347 | models, such as AIX 4.3. On such platforms, define | |
348 | @code{THREAD_MODEL_SPEC} such that it evaluates to a string without | |
349 | blanks that names one of the recognized thread models. @code{%*}, the | |
350 | default value of this macro, will expand to the value of | |
351 | @code{thread_file} set in @file{config.gcc}. | |
a2c4f8e0 | 352 | @end defmac |
008355a6 | 353 | |
a2c4f8e0 | 354 | @defmac SYSROOT_SUFFIX_SPEC |
73774972 EC |
355 | Define this macro to add a suffix to the target sysroot when GCC is |
356 | configured with a sysroot. This will cause GCC to search for usr/lib, | |
357 | et al, within sysroot+suffix. | |
a2c4f8e0 | 358 | @end defmac |
e7f13528 | 359 | |
a2c4f8e0 | 360 | @defmac SYSROOT_HEADERS_SUFFIX_SPEC |
73774972 EC |
361 | Define this macro to add a headers_suffix to the target sysroot when |
362 | GCC is configured with a sysroot. This will cause GCC to pass the | |
f4314bb6 | 363 | updated sysroot+headers_suffix to CPP, causing it to search for |
e7f13528 | 364 | usr/include, et al, within sysroot+headers_suffix. |
a2c4f8e0 | 365 | @end defmac |
e7f13528 | 366 | |
a2c4f8e0 | 367 | @defmac EXTRA_SPECS |
feca2ed3 JW |
368 | Define this macro to provide additional specifications to put in the |
369 | @file{specs} file that can be used in various specifications like | |
370 | @code{CC1_SPEC}. | |
371 | ||
372 | The definition should be an initializer for an array of structures, | |
373 | containing a string constant, that defines the specification name, and a | |
374 | string constant that provides the specification. | |
375 | ||
376 | Do not define this macro if it does not need to do anything. | |
377 | ||
378 | @code{EXTRA_SPECS} is useful when an architecture contains several | |
630d3d5a | 379 | related targets, which have various @code{@dots{}_SPECS} which are similar |
feca2ed3 JW |
380 | to each other, and the maintainer would like one central place to keep |
381 | these definitions. | |
382 | ||
383 | For example, the PowerPC System V.4 targets use @code{EXTRA_SPECS} to | |
384 | define either @code{_CALL_SYSV} when the System V calling sequence is | |
385 | used or @code{_CALL_AIX} when the older AIX-based calling sequence is | |
386 | used. | |
387 | ||
388 | The @file{config/rs6000/rs6000.h} target file defines: | |
389 | ||
3ab51846 | 390 | @smallexample |
feca2ed3 JW |
391 | #define EXTRA_SPECS \ |
392 | @{ "cpp_sysv_default", CPP_SYSV_DEFAULT @}, | |
393 | ||
394 | #define CPP_SYS_DEFAULT "" | |
3ab51846 | 395 | @end smallexample |
feca2ed3 JW |
396 | |
397 | The @file{config/rs6000/sysv.h} target file defines: | |
398 | @smallexample | |
399 | #undef CPP_SPEC | |
400 | #define CPP_SPEC \ | |
401 | "%@{posix: -D_POSIX_SOURCE @} \ | |
50d440bc NC |
402 | %@{mcall-sysv: -D_CALL_SYSV @} \ |
403 | %@{!mcall-sysv: %(cpp_sysv_default) @} \ | |
feca2ed3 JW |
404 | %@{msoft-float: -D_SOFT_FLOAT@} %@{mcpu=403: -D_SOFT_FLOAT@}" |
405 | ||
406 | #undef CPP_SYSV_DEFAULT | |
407 | #define CPP_SYSV_DEFAULT "-D_CALL_SYSV" | |
408 | @end smallexample | |
409 | ||
410 | while the @file{config/rs6000/eabiaix.h} target file defines | |
411 | @code{CPP_SYSV_DEFAULT} as: | |
412 | ||
413 | @smallexample | |
414 | #undef CPP_SYSV_DEFAULT | |
415 | #define CPP_SYSV_DEFAULT "-D_CALL_AIX" | |
416 | @end smallexample | |
a2c4f8e0 | 417 | @end defmac |
feca2ed3 | 418 | |
a2c4f8e0 | 419 | @defmac LINK_LIBGCC_SPECIAL_1 |
feca2ed3 JW |
420 | Define this macro if the driver program should find the library |
421 | @file{libgcc.a}. If you do not define this macro, the driver program will pass | |
630d3d5a | 422 | the argument @option{-lgcc} to tell the linker to do the search. |
a2c4f8e0 | 423 | @end defmac |
feca2ed3 | 424 | |
a2c4f8e0 | 425 | @defmac LINK_GCC_C_SEQUENCE_SPEC |
bbd7687d DM |
426 | The sequence in which libgcc and libc are specified to the linker. |
427 | By default this is @code{%G %L %G}. | |
a2c4f8e0 | 428 | @end defmac |
bbd7687d | 429 | |
a2c4f8e0 | 430 | @defmac LINK_COMMAND_SPEC |
9ec36da5 JL |
431 | A C string constant giving the complete command line need to execute the |
432 | linker. When you do this, you will need to update your port each time a | |
433 | change is made to the link command line within @file{gcc.c}. Therefore, | |
434 | define this macro only if you need to completely redefine the command | |
435 | line for invoking the linker and there is no other way to accomplish | |
bbd7687d DM |
436 | the effect you need. Overriding this macro may be avoidable by overriding |
437 | @code{LINK_GCC_C_SEQUENCE_SPEC} instead. | |
a2c4f8e0 | 438 | @end defmac |
9ec36da5 | 439 | |
a2c4f8e0 | 440 | @defmac LINK_ELIMINATE_DUPLICATE_LDIRECTORIES |
2cc07db4 | 441 | A nonzero value causes @command{collect2} to remove duplicate @option{-L@var{directory}} search |
5897739e JO |
442 | directories from linking commands. Do not give it a nonzero value if |
443 | removing duplicate search directories changes the linker's semantics. | |
a2c4f8e0 | 444 | @end defmac |
5897739e | 445 | |
a2c4f8e0 | 446 | @defmac MULTILIB_DEFAULTS |
feca2ed3 JW |
447 | Define this macro as a C expression for the initializer of an array of |
448 | string to tell the driver program which options are defaults for this | |
449 | target and thus do not need to be handled specially when using | |
450 | @code{MULTILIB_OPTIONS}. | |
451 | ||
452 | Do not define this macro if @code{MULTILIB_OPTIONS} is not defined in | |
453 | the target makefile fragment or if none of the options listed in | |
454 | @code{MULTILIB_OPTIONS} are set by default. | |
455 | @xref{Target Fragment}. | |
a2c4f8e0 | 456 | @end defmac |
feca2ed3 | 457 | |
a2c4f8e0 | 458 | @defmac RELATIVE_PREFIX_NOT_LINKDIR |
05739753 | 459 | Define this macro to tell @command{gcc} that it should only translate |
630d3d5a | 460 | a @option{-B} prefix into a @option{-L} linker option if the prefix |
feca2ed3 | 461 | indicates an absolute file name. |
a2c4f8e0 | 462 | @end defmac |
feca2ed3 | 463 | |
a2c4f8e0 | 464 | @defmac MD_EXEC_PREFIX |
feca2ed3 JW |
465 | If defined, this macro is an additional prefix to try after |
466 | @code{STANDARD_EXEC_PREFIX}. @code{MD_EXEC_PREFIX} is not searched | |
630d3d5a | 467 | when the @option{-b} option is used, or the compiler is built as a cross |
5505263f JL |
468 | compiler. If you define @code{MD_EXEC_PREFIX}, then be sure to add it |
469 | to the list of directories used to find the assembler in @file{configure.in}. | |
a2c4f8e0 | 470 | @end defmac |
feca2ed3 | 471 | |
a2c4f8e0 | 472 | @defmac STANDARD_STARTFILE_PREFIX |
feca2ed3 | 473 | Define this macro as a C string constant if you wish to override the |
0d037580 | 474 | standard choice of @code{libdir} as the default prefix to |
feca2ed3 | 475 | try when searching for startup files such as @file{crt0.o}. |
0d037580 DJ |
476 | @code{STANDARD_STARTFILE_PREFIX} is not searched when the compiler |
477 | is built as a cross compiler. | |
a2c4f8e0 | 478 | @end defmac |
feca2ed3 | 479 | |
656c7a3a AL |
480 | @defmac STANDARD_STARTFILE_PREFIX_1 |
481 | Define this macro as a C string constant if you wish to override the | |
482 | standard choice of @code{/lib} as a prefix to try after the default prefix | |
483 | when searching for startup files such as @file{crt0.o}. | |
484 | @code{STANDARD_STARTFILE_PREFIX_1} is not searched when the compiler | |
485 | is built as a cross compiler. | |
486 | @end defmac | |
487 | ||
488 | @defmac STANDARD_STARTFILE_PREFIX_2 | |
489 | Define this macro as a C string constant if you wish to override the | |
490 | standard choice of @code{/lib} as yet another prefix to try after the | |
491 | default prefix when searching for startup files such as @file{crt0.o}. | |
492 | @code{STANDARD_STARTFILE_PREFIX_2} is not searched when the compiler | |
493 | is built as a cross compiler. | |
494 | @end defmac | |
495 | ||
a2c4f8e0 | 496 | @defmac MD_STARTFILE_PREFIX |
feca2ed3 JW |
497 | If defined, this macro supplies an additional prefix to try after the |
498 | standard prefixes. @code{MD_EXEC_PREFIX} is not searched when the | |
630d3d5a | 499 | @option{-b} option is used, or when the compiler is built as a cross |
feca2ed3 | 500 | compiler. |
a2c4f8e0 | 501 | @end defmac |
feca2ed3 | 502 | |
a2c4f8e0 | 503 | @defmac MD_STARTFILE_PREFIX_1 |
feca2ed3 | 504 | If defined, this macro supplies yet another prefix to try after the |
630d3d5a | 505 | standard prefixes. It is not searched when the @option{-b} option is |
feca2ed3 | 506 | used, or when the compiler is built as a cross compiler. |
a2c4f8e0 | 507 | @end defmac |
feca2ed3 | 508 | |
a2c4f8e0 | 509 | @defmac INIT_ENVIRONMENT |
e9a25f70 | 510 | Define this macro as a C string constant if you wish to set environment |
feca2ed3 JW |
511 | variables for programs called by the driver, such as the assembler and |
512 | loader. The driver passes the value of this macro to @code{putenv} to | |
513 | initialize the necessary environment variables. | |
a2c4f8e0 | 514 | @end defmac |
feca2ed3 | 515 | |
a2c4f8e0 | 516 | @defmac LOCAL_INCLUDE_DIR |
feca2ed3 JW |
517 | Define this macro as a C string constant if you wish to override the |
518 | standard choice of @file{/usr/local/include} as the default prefix to | |
519 | try when searching for local header files. @code{LOCAL_INCLUDE_DIR} | |
520 | comes before @code{SYSTEM_INCLUDE_DIR} in the search order. | |
521 | ||
c237e94a ZW |
522 | Cross compilers do not search either @file{/usr/local/include} or its |
523 | replacement. | |
a2c4f8e0 | 524 | @end defmac |
feca2ed3 | 525 | |
a2c4f8e0 ZW |
526 | @defmac MODIFY_TARGET_NAME |
527 | Define this macro if you wish to define command-line switches that | |
528 | modify the default target name. | |
dc36ec2c RK |
529 | |
530 | For each switch, you can include a string to be appended to the first | |
531 | part of the configuration name or a string to be deleted from the | |
532 | configuration name, if present. The definition should be an initializer | |
533 | for an array of structures. Each array element should have three | |
534 | elements: the switch name (a string constant, including the initial | |
535 | dash), one of the enumeration codes @code{ADD} or @code{DELETE} to | |
536 | indicate whether the string should be inserted or deleted, and the string | |
537 | to be inserted or deleted (a string constant). | |
538 | ||
539 | For example, on a machine where @samp{64} at the end of the | |
630d3d5a JM |
540 | configuration name denotes a 64-bit target and you want the @option{-32} |
541 | and @option{-64} switches to select between 32- and 64-bit targets, you would | |
dc36ec2c RK |
542 | code |
543 | ||
544 | @smallexample | |
545 | #define MODIFY_TARGET_NAME \ | |
546 | @{ @{ "-32", DELETE, "64"@}, \ | |
547 | @{"-64", ADD, "64"@}@} | |
548 | @end smallexample | |
a2c4f8e0 | 549 | @end defmac |
dc36ec2c | 550 | |
a2c4f8e0 | 551 | @defmac SYSTEM_INCLUDE_DIR |
feca2ed3 JW |
552 | Define this macro as a C string constant if you wish to specify a |
553 | system-specific directory to search for header files before the standard | |
554 | directory. @code{SYSTEM_INCLUDE_DIR} comes before | |
555 | @code{STANDARD_INCLUDE_DIR} in the search order. | |
556 | ||
557 | Cross compilers do not use this macro and do not search the directory | |
558 | specified. | |
a2c4f8e0 | 559 | @end defmac |
feca2ed3 | 560 | |
a2c4f8e0 | 561 | @defmac STANDARD_INCLUDE_DIR |
feca2ed3 JW |
562 | Define this macro as a C string constant if you wish to override the |
563 | standard choice of @file{/usr/include} as the default prefix to | |
564 | try when searching for header files. | |
565 | ||
a2c4f8e0 | 566 | Cross compilers ignore this macro and do not search either |
feca2ed3 | 567 | @file{/usr/include} or its replacement. |
a2c4f8e0 | 568 | @end defmac |
feca2ed3 | 569 | |
a2c4f8e0 | 570 | @defmac STANDARD_INCLUDE_COMPONENT |
e9a25f70 JL |
571 | The ``component'' corresponding to @code{STANDARD_INCLUDE_DIR}. |
572 | See @code{INCLUDE_DEFAULTS}, below, for the description of components. | |
573 | If you do not define this macro, no component is used. | |
a2c4f8e0 | 574 | @end defmac |
e9a25f70 | 575 | |
a2c4f8e0 | 576 | @defmac INCLUDE_DEFAULTS |
feca2ed3 | 577 | Define this macro if you wish to override the entire default search path |
e9a25f70 JL |
578 | for include files. For a native compiler, the default search path |
579 | usually consists of @code{GCC_INCLUDE_DIR}, @code{LOCAL_INCLUDE_DIR}, | |
feca2ed3 JW |
580 | @code{SYSTEM_INCLUDE_DIR}, @code{GPLUSPLUS_INCLUDE_DIR}, and |
581 | @code{STANDARD_INCLUDE_DIR}. In addition, @code{GPLUSPLUS_INCLUDE_DIR} | |
582 | and @code{GCC_INCLUDE_DIR} are defined automatically by @file{Makefile}, | |
161d7b59 | 583 | and specify private search areas for GCC@. The directory |
feca2ed3 JW |
584 | @code{GPLUSPLUS_INCLUDE_DIR} is used only for C++ programs. |
585 | ||
586 | The definition should be an initializer for an array of structures. | |
e9a25f70 | 587 | Each array element should have four elements: the directory name (a |
9f6dc500 HPN |
588 | string constant), the component name (also a string constant), a flag |
589 | for C++-only directories, | |
e9a25f70 JL |
590 | and a flag showing that the includes in the directory don't need to be |
591 | wrapped in @code{extern @samp{C}} when compiling C++. Mark the end of | |
592 | the array with a null element. | |
593 | ||
594 | The component name denotes what GNU package the include file is part of, | |
4bd0bee9 | 595 | if any, in all uppercase letters. For example, it might be @samp{GCC} |
9f6dc500 | 596 | or @samp{BINUTILS}. If the package is part of a vendor-supplied |
e9a25f70 JL |
597 | operating system, code the component name as @samp{0}. |
598 | ||
e9a25f70 | 599 | For example, here is the definition used for VAX/VMS: |
feca2ed3 | 600 | |
3ab51846 | 601 | @smallexample |
feca2ed3 JW |
602 | #define INCLUDE_DEFAULTS \ |
603 | @{ \ | |
e9a25f70 JL |
604 | @{ "GNU_GXX_INCLUDE:", "G++", 1, 1@}, \ |
605 | @{ "GNU_CC_INCLUDE:", "GCC", 0, 0@}, \ | |
606 | @{ "SYS$SYSROOT:[SYSLIB.]", 0, 0, 0@}, \ | |
607 | @{ ".", 0, 0, 0@}, \ | |
608 | @{ 0, 0, 0, 0@} \ | |
feca2ed3 | 609 | @} |
3ab51846 | 610 | @end smallexample |
a2c4f8e0 | 611 | @end defmac |
feca2ed3 JW |
612 | |
613 | Here is the order of prefixes tried for exec files: | |
614 | ||
615 | @enumerate | |
616 | @item | |
630d3d5a | 617 | Any prefixes specified by the user with @option{-B}. |
feca2ed3 JW |
618 | |
619 | @item | |
fe037b8a CD |
620 | The environment variable @code{GCC_EXEC_PREFIX} or, if @code{GCC_EXEC_PREFIX} |
621 | is not set and the compiler has not been installed in the configure-time | |
622 | @var{prefix}, the location in which the compiler has actually been installed. | |
feca2ed3 JW |
623 | |
624 | @item | |
625 | The directories specified by the environment variable @code{COMPILER_PATH}. | |
626 | ||
627 | @item | |
fe037b8a CD |
628 | The macro @code{STANDARD_EXEC_PREFIX}, if the compiler has been installed |
629 | in the configured-time @var{prefix}. | |
feca2ed3 JW |
630 | |
631 | @item | |
fe037b8a | 632 | The location @file{/usr/libexec/gcc/}, but only if this is a native compiler. |
feca2ed3 JW |
633 | |
634 | @item | |
fe037b8a CD |
635 | The location @file{/usr/lib/gcc/}, but only if this is a native compiler. |
636 | ||
637 | @item | |
638 | The macro @code{MD_EXEC_PREFIX}, if defined, but only if this is a native | |
639 | compiler. | |
feca2ed3 JW |
640 | @end enumerate |
641 | ||
642 | Here is the order of prefixes tried for startfiles: | |
643 | ||
644 | @enumerate | |
645 | @item | |
630d3d5a | 646 | Any prefixes specified by the user with @option{-B}. |
feca2ed3 JW |
647 | |
648 | @item | |
fe037b8a CD |
649 | The environment variable @code{GCC_EXEC_PREFIX} or its automatically determined |
650 | value based on the installed toolchain location. | |
feca2ed3 JW |
651 | |
652 | @item | |
653 | The directories specified by the environment variable @code{LIBRARY_PATH} | |
512b62fb | 654 | (or port-specific name; native only, cross compilers do not use this). |
feca2ed3 JW |
655 | |
656 | @item | |
fe037b8a CD |
657 | The macro @code{STANDARD_EXEC_PREFIX}, but only if the toolchain is installed |
658 | in the configured @var{prefix} or this is a native compiler. | |
feca2ed3 JW |
659 | |
660 | @item | |
fe037b8a CD |
661 | The location @file{/usr/lib/gcc/}, but only if this is a native compiler. |
662 | ||
663 | @item | |
664 | The macro @code{MD_EXEC_PREFIX}, if defined, but only if this is a native | |
665 | compiler. | |
feca2ed3 JW |
666 | |
667 | @item | |
fe037b8a CD |
668 | The macro @code{MD_STARTFILE_PREFIX}, if defined, but only if this is a |
669 | native compiler, or we have a target system root. | |
feca2ed3 JW |
670 | |
671 | @item | |
fe037b8a CD |
672 | The macro @code{MD_STARTFILE_PREFIX_1}, if defined, but only if this is a |
673 | native compiler, or we have a target system root. | |
feca2ed3 JW |
674 | |
675 | @item | |
fe037b8a CD |
676 | The macro @code{STANDARD_STARTFILE_PREFIX}, with any sysroot modifications. |
677 | If this path is relative it will be prefixed by @code{GCC_EXEC_PREFIX} and | |
678 | the machine suffix or @code{STANDARD_EXEC_PREFIX} and the machine suffix. | |
feca2ed3 JW |
679 | |
680 | @item | |
fe037b8a CD |
681 | The macro @code{STANDARD_STARTFILE_PREFIX_1}, but only if this is a native |
682 | compiler, or we have a target system root. The default for this macro is | |
feca2ed3 JW |
683 | @file{/lib/}. |
684 | ||
685 | @item | |
fe037b8a CD |
686 | The macro @code{STANDARD_STARTFILE_PREFIX_2}, but only if this is a native |
687 | compiler, or we have a target system root. The default for this macro is | |
feca2ed3 JW |
688 | @file{/usr/lib/}. |
689 | @end enumerate | |
690 | ||
691 | @node Run-time Target | |
692 | @section Run-time Target Specification | |
693 | @cindex run-time target specification | |
694 | @cindex predefined macros | |
695 | @cindex target specifications | |
696 | ||
697 | @c prevent bad page break with this line | |
698 | Here are run-time target specifications. | |
699 | ||
a2c4f8e0 | 700 | @defmac TARGET_CPU_CPP_BUILTINS () |
12a41c22 | 701 | This function-like macro expands to a block of code that defines |
44082375 | 702 | built-in preprocessor macros and assertions for the target CPU, using |
1f95326c | 703 | the functions @code{builtin_define}, @code{builtin_define_std} and |
cb60f38d | 704 | @code{builtin_assert}. When the front end |
12a41c22 NB |
705 | calls this macro it provides a trailing semicolon, and since it has |
706 | finished command line option processing your code can use those | |
707 | results freely. | |
3df89291 NB |
708 | |
709 | @code{builtin_assert} takes a string in the form you pass to the | |
710 | command-line option @option{-A}, such as @code{cpu=mips}, and creates | |
d90a95fb | 711 | the assertion. @code{builtin_define} takes a string in the form |
3df89291 NB |
712 | accepted by option @option{-D} and unconditionally defines the macro. |
713 | ||
d90a95fb | 714 | @code{builtin_define_std} takes a string representing the name of an |
3df89291 | 715 | object-like macro. If it doesn't lie in the user's namespace, |
d90a95fb | 716 | @code{builtin_define_std} defines it unconditionally. Otherwise, it |
3df89291 NB |
717 | defines a version with two leading underscores, and another version |
718 | with two leading and trailing underscores, and defines the original | |
719 | only if an ISO standard was not requested on the command line. For | |
720 | example, passing @code{unix} defines @code{__unix}, @code{__unix__} | |
721 | and possibly @code{unix}; passing @code{_mips} defines @code{__mips}, | |
722 | @code{__mips__} and possibly @code{_mips}, and passing @code{_ABI64} | |
723 | defines only @code{_ABI64}. | |
724 | ||
e0322d5c NB |
725 | You can also test for the C dialect being compiled. The variable |
726 | @code{c_language} is set to one of @code{clk_c}, @code{clk_cplusplus} | |
727 | or @code{clk_objective_c}. Note that if we are preprocessing | |
728 | assembler, this variable will be @code{clk_c} but the function-like | |
729 | macro @code{preprocessing_asm_p()} will return true, so you might want | |
ce3649d2 | 730 | to check for that first. If you need to check for strict ANSI, the |
c219e1da JDA |
731 | variable @code{flag_iso} can be used. The function-like macro |
732 | @code{preprocessing_trad_p()} can be used to check for traditional | |
733 | preprocessing. | |
a2c4f8e0 | 734 | @end defmac |
e0322d5c | 735 | |
a2c4f8e0 | 736 | @defmac TARGET_OS_CPP_BUILTINS () |
12a41c22 NB |
737 | Similarly to @code{TARGET_CPU_CPP_BUILTINS} but this macro is optional |
738 | and is used for the target operating system instead. | |
a2c4f8e0 | 739 | @end defmac |
12a41c22 | 740 | |
a2c4f8e0 | 741 | @defmac TARGET_OBJFMT_CPP_BUILTINS () |
4e2e315f NB |
742 | Similarly to @code{TARGET_CPU_CPP_BUILTINS} but this macro is optional |
743 | and is used for the target object format. @file{elfos.h} uses this | |
744 | macro to define @code{__ELF__}, so you probably do not need to define | |
745 | it yourself. | |
a2c4f8e0 | 746 | @end defmac |
4e2e315f | 747 | |
a2c4f8e0 | 748 | @deftypevar {extern int} target_flags |
75685792 RS |
749 | This variable is declared in @file{options.h}, which is included before |
750 | any target-specific headers. | |
a2c4f8e0 | 751 | @end deftypevar |
feca2ed3 | 752 | |
9e3be889 | 753 | @deftypevr {Target Hook} int TARGET_DEFAULT_TARGET_FLAGS |
75685792 RS |
754 | This variable specifies the initial value of @code{target_flags}. |
755 | Its default setting is 0. | |
9e3be889 | 756 | @end deftypevr |
75685792 | 757 | |
bacf5b96 RS |
758 | @cindex optional hardware or system features |
759 | @cindex features, optional, in system conventions | |
760 | ||
75685792 RS |
761 | @deftypefn {Target Hook} bool TARGET_HANDLE_OPTION (size_t @var{code}, const char *@var{arg}, int @var{value}) |
762 | This hook is called whenever the user specifies one of the | |
763 | target-specific options described by the @file{.opt} definition files | |
764 | (@pxref{Options}). It has the opportunity to do some option-specific | |
765 | processing and should return true if the option is valid. The default | |
766 | definition does nothing but return true. | |
767 | ||
768 | @var{code} specifies the @code{OPT_@var{name}} enumeration value | |
769 | associated with the selected option; @var{name} is just a rendering of | |
770 | the option name in which non-alphanumeric characters are replaced by | |
771 | underscores. @var{arg} specifies the string argument and is null if | |
772 | no argument was given. If the option is flagged as a @code{UInteger} | |
773 | (@pxref{Option properties}), @var{value} is the numeric value of the | |
774 | argument. Otherwise @var{value} is 1 if the positive form of the | |
775 | option was used and 0 if the ``no-'' form was. | |
776 | @end deftypefn | |
777 | ||
1f1d5130 MS |
778 | @deftypefn {Target Hook} bool TARGET_HANDLE_C_OPTION (size_t @var{code}, const char *@var{arg}, int @var{value}) |
779 | This target hook is called whenever the user specifies one of the | |
780 | target-specific C language family options described by the @file{.opt} | |
781 | definition files(@pxref{Options}). It has the opportunity to do some | |
782 | option-specific processing and should return true if the option is | |
783 | valid. The default definition does nothing but return false. | |
784 | ||
785 | In general, you should use @code{TARGET_HANDLE_OPTION} to handle | |
786 | options. However, if processing an option requires routines that are | |
787 | only available in the C (and related language) front ends, then you | |
788 | should use @code{TARGET_HANDLE_C_OPTION} instead. | |
789 | @end deftypefn | |
790 | ||
a2c4f8e0 | 791 | @defmac TARGET_VERSION |
feca2ed3 JW |
792 | This macro is a C statement to print on @code{stderr} a string |
793 | describing the particular machine description choice. Every machine | |
794 | description should define @code{TARGET_VERSION}. For example: | |
795 | ||
796 | @smallexample | |
797 | #ifdef MOTOROLA | |
798 | #define TARGET_VERSION \ | |
799 | fprintf (stderr, " (68k, Motorola syntax)"); | |
800 | #else | |
801 | #define TARGET_VERSION \ | |
802 | fprintf (stderr, " (68k, MIT syntax)"); | |
803 | #endif | |
804 | @end smallexample | |
a2c4f8e0 | 805 | @end defmac |
feca2ed3 | 806 | |
a2c4f8e0 | 807 | @defmac OVERRIDE_OPTIONS |
feca2ed3 JW |
808 | Sometimes certain combinations of command options do not make sense on |
809 | a particular target machine. You can define a macro | |
810 | @code{OVERRIDE_OPTIONS} to take account of this. This macro, if | |
811 | defined, is executed once just after all the command options have been | |
812 | parsed. | |
813 | ||
814 | Don't use this macro to turn on various extra optimizations for | |
630d3d5a | 815 | @option{-O}. That is what @code{OPTIMIZATION_OPTIONS} is for. |
a2c4f8e0 | 816 | @end defmac |
feca2ed3 | 817 | |
c7b5e395 GK |
818 | @defmac C_COMMON_OVERRIDE_OPTIONS |
819 | This is similar to @code{OVERRIDE_OPTIONS} but is only used in the C | |
820 | language frontends (C, Objective-C, C++, Objective-C++) and so can be | |
821 | used to alter option flag variables which only exist in those | |
822 | frontends. | |
823 | @end defmac | |
824 | ||
a2c4f8e0 | 825 | @defmac OPTIMIZATION_OPTIONS (@var{level}, @var{size}) |
feca2ed3 JW |
826 | Some machines may desire to change what optimizations are performed for |
827 | various optimization levels. This macro, if defined, is executed once | |
828 | just after the optimization level is determined and before the remainder | |
829 | of the command options have been parsed. Values set in this macro are | |
830 | used as the default values for the other command line options. | |
831 | ||
630d3d5a JM |
832 | @var{level} is the optimization level specified; 2 if @option{-O2} is |
833 | specified, 1 if @option{-O} is specified, and 0 if neither is specified. | |
feca2ed3 | 834 | |
df2a54e9 | 835 | @var{size} is nonzero if @option{-Os} is specified and zero otherwise. |
c6aded7c | 836 | |
a51fa0f4 MM |
837 | This macro is run once at program startup and when the optimization |
838 | options are changed via @code{#pragma GCC optimize} or by using the | |
839 | @code{optimize} attribute. | |
feca2ed3 JW |
840 | |
841 | @strong{Do not examine @code{write_symbols} in | |
842 | this macro!} The debugging options are not supposed to alter the | |
843 | generated code. | |
a2c4f8e0 | 844 | @end defmac |
feca2ed3 | 845 | |
67e6ba46 NC |
846 | @deftypefn {Target Hook} bool TARGET_HELP (void) |
847 | This hook is called in response to the user invoking | |
848 | @option{--target-help} on the command line. It gives the target a | |
849 | chance to display extra information on the target specific command | |
850 | line options found in its @file{.opt} file. | |
851 | @end deftypefn | |
852 | ||
a2c4f8e0 | 853 | @defmac CAN_DEBUG_WITHOUT_FP |
feca2ed3 | 854 | Define this macro if debugging can be performed even without a frame |
a3a15b4d | 855 | pointer. If this macro is defined, GCC will turn on the |
630d3d5a | 856 | @option{-fomit-frame-pointer} option whenever @option{-O} is specified. |
a2c4f8e0 | 857 | @end defmac |
feca2ed3 | 858 | |
414c4dc4 NC |
859 | @node Per-Function Data |
860 | @section Defining data structures for per-function information. | |
861 | @cindex per-function data | |
862 | @cindex data structures | |
863 | ||
864 | If the target needs to store information on a per-function basis, GCC | |
865 | provides a macro and a couple of variables to allow this. Note, just | |
866 | using statics to store the information is a bad idea, since GCC supports | |
867 | nested functions, so you can be halfway through encoding one function | |
868 | when another one comes along. | |
869 | ||
870 | GCC defines a data structure called @code{struct function} which | |
871 | contains all of the data specific to an individual function. This | |
872 | structure contains a field called @code{machine} whose type is | |
873 | @code{struct machine_function *}, which can be used by targets to point | |
874 | to their own specific data. | |
875 | ||
876 | If a target needs per-function specific data it should define the type | |
e2500fed GK |
877 | @code{struct machine_function} and also the macro @code{INIT_EXPANDERS}. |
878 | This macro should be used to initialize the function pointer | |
879 | @code{init_machine_status}. This pointer is explained below. | |
414c4dc4 NC |
880 | |
881 | One typical use of per-function, target specific data is to create an | |
882 | RTX to hold the register containing the function's return address. This | |
883 | RTX can then be used to implement the @code{__builtin_return_address} | |
884 | function, for level 0. | |
885 | ||
aee96fe9 | 886 | Note---earlier implementations of GCC used a single data area to hold |
414c4dc4 NC |
887 | all of the per-function information. Thus when processing of a nested |
888 | function began the old per-function data had to be pushed onto a | |
889 | stack, and when the processing was finished, it had to be popped off the | |
890 | stack. GCC used to provide function pointers called | |
02f52e19 | 891 | @code{save_machine_status} and @code{restore_machine_status} to handle |
414c4dc4 NC |
892 | the saving and restoring of the target specific information. Since the |
893 | single data area approach is no longer used, these pointers are no | |
894 | longer supported. | |
895 | ||
a2c4f8e0 | 896 | @defmac INIT_EXPANDERS |
c21cd8b1 | 897 | Macro called to initialize any target specific information. This macro |
414c4dc4 | 898 | is called once per function, before generation of any RTL has begun. |
c21cd8b1 | 899 | The intention of this macro is to allow the initialization of the |
a2c4f8e0 ZW |
900 | function pointer @code{init_machine_status}. |
901 | @end defmac | |
414c4dc4 | 902 | |
a2c4f8e0 ZW |
903 | @deftypevar {void (*)(struct function *)} init_machine_status |
904 | If this function pointer is non-@code{NULL} it will be called once per | |
905 | function, before function compilation starts, in order to allow the | |
906 | target to perform any target specific initialization of the | |
907 | @code{struct function} structure. It is intended that this would be | |
908 | used to initialize the @code{machine} of that structure. | |
414c4dc4 | 909 | |
8a36672b | 910 | @code{struct machine_function} structures are expected to be freed by GC@. |
e2500fed GK |
911 | Generally, any memory that they reference must be allocated by using |
912 | @code{ggc_alloc}, including the structure itself. | |
a2c4f8e0 | 913 | @end deftypevar |
414c4dc4 | 914 | |
feca2ed3 JW |
915 | @node Storage Layout |
916 | @section Storage Layout | |
917 | @cindex storage layout | |
918 | ||
919 | Note that the definitions of the macros in this table which are sizes or | |
920 | alignments measured in bits do not need to be constant. They can be C | |
921 | expressions that refer to static variables, such as the @code{target_flags}. | |
922 | @xref{Run-time Target}. | |
923 | ||
a2c4f8e0 | 924 | @defmac BITS_BIG_ENDIAN |
feca2ed3 JW |
925 | Define this macro to have the value 1 if the most significant bit in a |
926 | byte has the lowest number; otherwise define it to have the value zero. | |
927 | This means that bit-field instructions count from the most significant | |
928 | bit. If the machine has no bit-field instructions, then this must still | |
929 | be defined, but it doesn't matter which value it is defined to. This | |
930 | macro need not be a constant. | |
931 | ||
932 | This macro does not affect the way structure fields are packed into | |
933 | bytes or words; that is controlled by @code{BYTES_BIG_ENDIAN}. | |
a2c4f8e0 | 934 | @end defmac |
feca2ed3 | 935 | |
a2c4f8e0 | 936 | @defmac BYTES_BIG_ENDIAN |
feca2ed3 JW |
937 | Define this macro to have the value 1 if the most significant byte in a |
938 | word has the lowest number. This macro need not be a constant. | |
a2c4f8e0 | 939 | @end defmac |
feca2ed3 | 940 | |
a2c4f8e0 | 941 | @defmac WORDS_BIG_ENDIAN |
feca2ed3 JW |
942 | Define this macro to have the value 1 if, in a multiword object, the |
943 | most significant word has the lowest number. This applies to both | |
a3a15b4d | 944 | memory locations and registers; GCC fundamentally assumes that the |
feca2ed3 JW |
945 | order of words in memory is the same as the order in registers. This |
946 | macro need not be a constant. | |
a2c4f8e0 | 947 | @end defmac |
feca2ed3 | 948 | |
a2c4f8e0 | 949 | @defmac LIBGCC2_WORDS_BIG_ENDIAN |
aee96fe9 JM |
950 | Define this macro if @code{WORDS_BIG_ENDIAN} is not constant. This must be a |
951 | constant value with the same meaning as @code{WORDS_BIG_ENDIAN}, which will be | |
952 | used only when compiling @file{libgcc2.c}. Typically the value will be set | |
feca2ed3 | 953 | based on preprocessor defines. |
a2c4f8e0 | 954 | @end defmac |
feca2ed3 | 955 | |
a2c4f8e0 | 956 | @defmac FLOAT_WORDS_BIG_ENDIAN |
feca2ed3 JW |
957 | Define this macro to have the value 1 if @code{DFmode}, @code{XFmode} or |
958 | @code{TFmode} floating point numbers are stored in memory with the word | |
959 | containing the sign bit at the lowest address; otherwise define it to | |
960 | have the value 0. This macro need not be a constant. | |
961 | ||
962 | You need not define this macro if the ordering is the same as for | |
963 | multi-word integers. | |
a2c4f8e0 | 964 | @end defmac |
feca2ed3 | 965 | |
a2c4f8e0 | 966 | @defmac BITS_PER_UNIT |
feca2ed3 | 967 | Define this macro to be the number of bits in an addressable storage |
5c60f03d | 968 | unit (byte). If you do not define this macro the default is 8. |
a2c4f8e0 | 969 | @end defmac |
feca2ed3 | 970 | |
a2c4f8e0 | 971 | @defmac BITS_PER_WORD |
e81dd381 KG |
972 | Number of bits in a word. If you do not define this macro, the default |
973 | is @code{BITS_PER_UNIT * UNITS_PER_WORD}. | |
a2c4f8e0 | 974 | @end defmac |
feca2ed3 | 975 | |
a2c4f8e0 | 976 | @defmac MAX_BITS_PER_WORD |
feca2ed3 JW |
977 | Maximum number of bits in a word. If this is undefined, the default is |
978 | @code{BITS_PER_WORD}. Otherwise, it is the constant value that is the | |
979 | largest value that @code{BITS_PER_WORD} can have at run-time. | |
a2c4f8e0 | 980 | @end defmac |
feca2ed3 | 981 | |
a2c4f8e0 | 982 | @defmac UNITS_PER_WORD |
c4336539 PB |
983 | Number of storage units in a word; normally the size of a general-purpose |
984 | register, a power of two from 1 or 8. | |
a2c4f8e0 | 985 | @end defmac |
feca2ed3 | 986 | |
a2c4f8e0 | 987 | @defmac MIN_UNITS_PER_WORD |
feca2ed3 JW |
988 | Minimum number of units in a word. If this is undefined, the default is |
989 | @code{UNITS_PER_WORD}. Otherwise, it is the constant value that is the | |
990 | smallest value that @code{UNITS_PER_WORD} can have at run-time. | |
a2c4f8e0 | 991 | @end defmac |
feca2ed3 | 992 | |
9d3a9de1 L |
993 | @defmac UNITS_PER_SIMD_WORD (@var{mode}) |
994 | Number of units in the vectors that the vectorizer can produce for | |
995 | scalar mode @var{mode}. The default is equal to @code{UNITS_PER_WORD}, | |
996 | because the vectorizer can do some transformations even in absence of | |
997 | specialized @acronym{SIMD} hardware. | |
c4336539 PB |
998 | @end defmac |
999 | ||
a2c4f8e0 | 1000 | @defmac POINTER_SIZE |
feca2ed3 JW |
1001 | Width of a pointer, in bits. You must specify a value no wider than the |
1002 | width of @code{Pmode}. If it is not equal to the width of @code{Pmode}, | |
2465bf76 KG |
1003 | you must define @code{POINTERS_EXTEND_UNSIGNED}. If you do not specify |
1004 | a value the default is @code{BITS_PER_WORD}. | |
a2c4f8e0 | 1005 | @end defmac |
feca2ed3 | 1006 | |
a2c4f8e0 | 1007 | @defmac POINTERS_EXTEND_UNSIGNED |
4923a230 RS |
1008 | A C expression that determines how pointers should be extended from |
1009 | @code{ptr_mode} to either @code{Pmode} or @code{word_mode}. It is | |
1010 | greater than zero if pointers should be zero-extended, zero if they | |
1011 | should be sign-extended, and negative if some other sort of conversion | |
1012 | is needed. In the last case, the extension is done by the target's | |
1013 | @code{ptr_extend} instruction. | |
1014 | ||
1015 | You need not define this macro if the @code{ptr_mode}, @code{Pmode} | |
1016 | and @code{word_mode} are all the same width. | |
a2c4f8e0 | 1017 | @end defmac |
feca2ed3 | 1018 | |
a2c4f8e0 | 1019 | @defmac PROMOTE_MODE (@var{m}, @var{unsignedp}, @var{type}) |
feca2ed3 JW |
1020 | A macro to update @var{m} and @var{unsignedp} when an object whose type |
1021 | is @var{type} and which has the specified mode and signedness is to be | |
1022 | stored in a register. This macro is only called when @var{type} is a | |
1023 | scalar type. | |
1024 | ||
1025 | On most RISC machines, which only have operations that operate on a full | |
1026 | register, define this macro to set @var{m} to @code{word_mode} if | |
1027 | @var{m} is an integer mode narrower than @code{BITS_PER_WORD}. In most | |
1028 | cases, only integer modes should be widened because wider-precision | |
1029 | floating-point operations are usually more expensive than their narrower | |
1030 | counterparts. | |
1031 | ||
1032 | For most machines, the macro definition does not change @var{unsignedp}. | |
1033 | However, some machines, have instructions that preferentially handle | |
1034 | either signed or unsigned quantities of certain modes. For example, on | |
1035 | the DEC Alpha, 32-bit loads from memory and 32-bit add instructions | |
1036 | sign-extend the result to 64 bits. On such machines, set | |
1037 | @var{unsignedp} according to which kind of extension is more efficient. | |
1038 | ||
1039 | Do not define this macro if it would never modify @var{m}. | |
a2c4f8e0 | 1040 | @end defmac |
feca2ed3 | 1041 | |
d4453b7a PB |
1042 | @defmac PROMOTE_FUNCTION_MODE |
1043 | Like @code{PROMOTE_MODE}, but is applied to outgoing function arguments or | |
1044 | function return values, as specified by @code{TARGET_PROMOTE_FUNCTION_ARGS} | |
1045 | and @code{TARGET_PROMOTE_FUNCTION_RETURN}, respectively. | |
1046 | ||
1047 | The default is @code{PROMOTE_MODE}. | |
1048 | @end defmac | |
1049 | ||
61f71b34 DD |
1050 | @deftypefn {Target Hook} bool TARGET_PROMOTE_FUNCTION_ARGS (tree @var{fntype}) |
1051 | This target hook should return @code{true} if the promotion described by | |
d4453b7a PB |
1052 | @code{PROMOTE_FUNCTION_MODE} should be done for outgoing function |
1053 | arguments. | |
61f71b34 | 1054 | @end deftypefn |
feca2ed3 | 1055 | |
61f71b34 DD |
1056 | @deftypefn {Target Hook} bool TARGET_PROMOTE_FUNCTION_RETURN (tree @var{fntype}) |
1057 | This target hook should return @code{true} if the promotion described by | |
d4453b7a | 1058 | @code{PROMOTE_FUNCTION_MODE} should be done for the return value of |
61f71b34 | 1059 | functions. |
feca2ed3 | 1060 | |
1b03c58a RG |
1061 | If this target hook returns @code{true}, @code{TARGET_FUNCTION_VALUE} |
1062 | must perform the same promotions done by @code{PROMOTE_FUNCTION_MODE}. | |
61f71b34 | 1063 | @end deftypefn |
feca2ed3 | 1064 | |
a2c4f8e0 | 1065 | @defmac PARM_BOUNDARY |
feca2ed3 JW |
1066 | Normal alignment required for function parameters on the stack, in |
1067 | bits. All stack parameters receive at least this much alignment | |
1068 | regardless of data type. On most machines, this is the same as the | |
1069 | size of an integer. | |
a2c4f8e0 | 1070 | @end defmac |
feca2ed3 | 1071 | |
a2c4f8e0 | 1072 | @defmac STACK_BOUNDARY |
31cdd499 ZW |
1073 | Define this macro to the minimum alignment enforced by hardware for the |
1074 | stack pointer on this machine. The definition is a C expression for the | |
1075 | desired alignment (measured in bits). This value is used as a default | |
1076 | if @code{PREFERRED_STACK_BOUNDARY} is not defined. On most machines, | |
1077 | this should be the same as @code{PARM_BOUNDARY}. | |
a2c4f8e0 | 1078 | @end defmac |
c795bca9 | 1079 | |
a2c4f8e0 | 1080 | @defmac PREFERRED_STACK_BOUNDARY |
31cdd499 ZW |
1081 | Define this macro if you wish to preserve a certain alignment for the |
1082 | stack pointer, greater than what the hardware enforces. The definition | |
1083 | is a C expression for the desired alignment (measured in bits). This | |
1084 | macro must evaluate to a value equal to or larger than | |
1085 | @code{STACK_BOUNDARY}. | |
a2c4f8e0 | 1086 | @end defmac |
feca2ed3 | 1087 | |
2e3f842f L |
1088 | @defmac INCOMING_STACK_BOUNDARY |
1089 | Define this macro if the incoming stack boundary may be different | |
1090 | from @code{PREFERRED_STACK_BOUNDARY}. This macro must evaluate | |
1091 | to a value equal to or larger than @code{STACK_BOUNDARY}. | |
1092 | @end defmac | |
1093 | ||
a2c4f8e0 | 1094 | @defmac FUNCTION_BOUNDARY |
feca2ed3 | 1095 | Alignment required for a function entry point, in bits. |
a2c4f8e0 | 1096 | @end defmac |
feca2ed3 | 1097 | |
a2c4f8e0 | 1098 | @defmac BIGGEST_ALIGNMENT |
c4f46fde DD |
1099 | Biggest alignment that any data type can require on this machine, in |
1100 | bits. Note that this is not the biggest alignment that is supported, | |
1101 | just the biggest alignment that, when violated, may cause a fault. | |
a2c4f8e0 | 1102 | @end defmac |
feca2ed3 | 1103 | |
95331614 OH |
1104 | @defmac MALLOC_ABI_ALIGNMENT |
1105 | Alignment, in bits, a C conformant malloc implementation has to | |
1106 | provide. If not defined, the default value is @code{BITS_PER_WORD}. | |
1107 | @end defmac | |
1108 | ||
6e4f1168 L |
1109 | @defmac ATTRIBUTE_ALIGNED_VALUE |
1110 | Alignment used by the @code{__attribute__ ((aligned))} construct. If | |
1111 | not defined, the default value is @code{BIGGEST_ALIGNMENT}. | |
1112 | @end defmac | |
1113 | ||
a2c4f8e0 | 1114 | @defmac MINIMUM_ATOMIC_ALIGNMENT |
861bb6c1 JL |
1115 | If defined, the smallest alignment, in bits, that can be given to an |
1116 | object that can be referenced in one operation, without disturbing any | |
1117 | nearby object. Normally, this is @code{BITS_PER_UNIT}, but may be larger | |
1118 | on machines that don't have byte or half-word store operations. | |
a2c4f8e0 | 1119 | @end defmac |
861bb6c1 | 1120 | |
a2c4f8e0 | 1121 | @defmac BIGGEST_FIELD_ALIGNMENT |
11cf4d18 JJ |
1122 | Biggest alignment that any structure or union field can require on this |
1123 | machine, in bits. If defined, this overrides @code{BIGGEST_ALIGNMENT} for | |
1124 | structure and union fields only, unless the field alignment has been set | |
1125 | by the @code{__attribute__ ((aligned (@var{n})))} construct. | |
a2c4f8e0 | 1126 | @end defmac |
feca2ed3 | 1127 | |
a2c4f8e0 | 1128 | @defmac ADJUST_FIELD_ALIGN (@var{field}, @var{computed}) |
feca2ed3 | 1129 | An expression for the alignment of a structure field @var{field} if the |
ad9335eb JJ |
1130 | alignment computed in the usual way (including applying of |
1131 | @code{BIGGEST_ALIGNMENT} and @code{BIGGEST_FIELD_ALIGNMENT} to the | |
1132 | alignment) is @var{computed}. It overrides alignment only if the | |
1133 | field alignment has not been set by the | |
1134 | @code{__attribute__ ((aligned (@var{n})))} construct. | |
a2c4f8e0 | 1135 | @end defmac |
feca2ed3 | 1136 | |
2e3f842f L |
1137 | @defmac MAX_STACK_ALIGNMENT |
1138 | Biggest stack alignment guaranteed by the backend. Use this macro | |
1139 | to specify the maximum alignment of a variable on stack. | |
1140 | ||
1141 | If not defined, the default value is @code{STACK_BOUNDARY}. | |
1142 | ||
1143 | @c FIXME: The default should be @code{PREFERRED_STACK_BOUNDARY}. | |
1144 | @c But the fix for PR 32893 indicates that we can only guarantee | |
1145 | @c maximum stack alignment on stack up to @code{STACK_BOUNDARY}, not | |
1146 | @c @code{PREFERRED_STACK_BOUNDARY}, if stack alignment isn't supported. | |
1147 | @end defmac | |
1148 | ||
a2c4f8e0 | 1149 | @defmac MAX_OFILE_ALIGNMENT |
feca2ed3 JW |
1150 | Biggest alignment supported by the object file format of this machine. |
1151 | Use this macro to limit the alignment which can be specified using the | |
1152 | @code{__attribute__ ((aligned (@var{n})))} construct. If not defined, | |
1153 | the default value is @code{BIGGEST_ALIGNMENT}. | |
11d90e2d CD |
1154 | |
1155 | On systems that use ELF, the default (in @file{config/elfos.h}) is | |
1156 | the largest supported 32-bit ELF section alignment representable on | |
1157 | a 32-bit host e.g. @samp{(((unsigned HOST_WIDEST_INT) 1 << 28) * 8)}. | |
1158 | On 32-bit ELF the largest supported section alignment in bits is | |
1159 | @samp{(0x80000000 * 8)}, but this is not representable on 32-bit hosts. | |
a2c4f8e0 | 1160 | @end defmac |
feca2ed3 | 1161 | |
a2c4f8e0 | 1162 | @defmac DATA_ALIGNMENT (@var{type}, @var{basic-align}) |
a8d1550a | 1163 | If defined, a C expression to compute the alignment for a variable in |
8a198bd2 JW |
1164 | the static store. @var{type} is the data type, and @var{basic-align} is |
1165 | the alignment that the object would ordinarily have. The value of this | |
feca2ed3 JW |
1166 | macro is used instead of that alignment to align the object. |
1167 | ||
1168 | If this macro is not defined, then @var{basic-align} is used. | |
1169 | ||
1170 | @findex strcpy | |
1171 | One use of this macro is to increase alignment of medium-size data to | |
1172 | make it all fit in fewer cache lines. Another is to cause character | |
1173 | arrays to be word-aligned so that @code{strcpy} calls that copy | |
1174 | constants to character arrays can be done inline. | |
a2c4f8e0 | 1175 | @end defmac |
feca2ed3 | 1176 | |
a2c4f8e0 | 1177 | @defmac CONSTANT_ALIGNMENT (@var{constant}, @var{basic-align}) |
feca2ed3 JW |
1178 | If defined, a C expression to compute the alignment given to a constant |
1179 | that is being placed in memory. @var{constant} is the constant and | |
1180 | @var{basic-align} is the alignment that the object would ordinarily | |
1181 | have. The value of this macro is used instead of that alignment to | |
1182 | align the object. | |
1183 | ||
1184 | If this macro is not defined, then @var{basic-align} is used. | |
1185 | ||
1186 | The typical use of this macro is to increase alignment for string | |
1187 | constants to be word aligned so that @code{strcpy} calls that copy | |
1188 | constants can be done inline. | |
a2c4f8e0 | 1189 | @end defmac |
feca2ed3 | 1190 | |
a2c4f8e0 | 1191 | @defmac LOCAL_ALIGNMENT (@var{type}, @var{basic-align}) |
a8d1550a | 1192 | If defined, a C expression to compute the alignment for a variable in |
d16790f2 JW |
1193 | the local store. @var{type} is the data type, and @var{basic-align} is |
1194 | the alignment that the object would ordinarily have. The value of this | |
1195 | macro is used instead of that alignment to align the object. | |
1196 | ||
1197 | If this macro is not defined, then @var{basic-align} is used. | |
1198 | ||
1199 | One use of this macro is to increase alignment of medium-size data to | |
1200 | make it all fit in fewer cache lines. | |
a2c4f8e0 | 1201 | @end defmac |
d16790f2 | 1202 | |
76fe54f0 L |
1203 | @defmac STACK_SLOT_ALIGNMENT (@var{type}, @var{mode}, @var{basic-align}) |
1204 | If defined, a C expression to compute the alignment for stack slot. | |
1205 | @var{type} is the data type, @var{mode} is the widest mode available, | |
1206 | and @var{basic-align} is the alignment that the slot would ordinarily | |
1207 | have. The value of this macro is used instead of that alignment to | |
1208 | align the slot. | |
1209 | ||
1210 | If this macro is not defined, then @var{basic-align} is used when | |
1211 | @var{type} is @code{NULL}. Otherwise, @code{LOCAL_ALIGNMENT} will | |
1212 | be used. | |
1213 | ||
1214 | This macro is to set alignment of stack slot to the maximum alignment | |
1215 | of all possible modes which the slot may have. | |
1216 | @end defmac | |
1217 | ||
9bfaf89d JJ |
1218 | @defmac LOCAL_DECL_ALIGNMENT (@var{decl}) |
1219 | If defined, a C expression to compute the alignment for a local | |
1220 | variable @var{decl}. | |
1221 | ||
1222 | If this macro is not defined, then | |
1223 | @code{LOCAL_ALIGNMENT (TREE_TYPE (@var{decl}), DECL_ALIGN (@var{decl}))} | |
1224 | is used. | |
1225 | ||
1226 | One use of this macro is to increase alignment of medium-size data to | |
1227 | make it all fit in fewer cache lines. | |
1228 | @end defmac | |
1229 | ||
a2c4f8e0 | 1230 | @defmac EMPTY_FIELD_BOUNDARY |
c771326b | 1231 | Alignment in bits to be given to a structure bit-field that follows an |
feca2ed3 JW |
1232 | empty field such as @code{int : 0;}. |
1233 | ||
78d55cc8 | 1234 | If @code{PCC_BITFIELD_TYPE_MATTERS} is true, it overrides this macro. |
a2c4f8e0 | 1235 | @end defmac |
feca2ed3 | 1236 | |
a2c4f8e0 | 1237 | @defmac STRUCTURE_SIZE_BOUNDARY |
feca2ed3 JW |
1238 | Number of bits which any structure or union's size must be a multiple of. |
1239 | Each structure or union's size is rounded up to a multiple of this. | |
1240 | ||
1241 | If you do not define this macro, the default is the same as | |
1242 | @code{BITS_PER_UNIT}. | |
a2c4f8e0 | 1243 | @end defmac |
feca2ed3 | 1244 | |
a2c4f8e0 | 1245 | @defmac STRICT_ALIGNMENT |
feca2ed3 JW |
1246 | Define this macro to be the value 1 if instructions will fail to work |
1247 | if given data not on the nominal alignment. If instructions will merely | |
1248 | go slower in that case, define this macro as 0. | |
a2c4f8e0 | 1249 | @end defmac |
feca2ed3 | 1250 | |
a2c4f8e0 | 1251 | @defmac PCC_BITFIELD_TYPE_MATTERS |
feca2ed3 | 1252 | Define this if you wish to imitate the way many other C compilers handle |
c771326b | 1253 | alignment of bit-fields and the structures that contain them. |
feca2ed3 | 1254 | |
8dc65b6e MM |
1255 | The behavior is that the type written for a named bit-field (@code{int}, |
1256 | @code{short}, or other integer type) imposes an alignment for the entire | |
1257 | structure, as if the structure really did contain an ordinary field of | |
1258 | that type. In addition, the bit-field is placed within the structure so | |
1259 | that it would fit within such a field, not crossing a boundary for it. | |
1260 | ||
1261 | Thus, on most machines, a named bit-field whose type is written as | |
1262 | @code{int} would not cross a four-byte boundary, and would force | |
1263 | four-byte alignment for the whole structure. (The alignment used may | |
1264 | not be four bytes; it is controlled by the other alignment parameters.) | |
1265 | ||
1266 | An unnamed bit-field will not affect the alignment of the containing | |
1267 | structure. | |
feca2ed3 JW |
1268 | |
1269 | If the macro is defined, its definition should be a C expression; | |
1270 | a nonzero value for the expression enables this behavior. | |
1271 | ||
1272 | Note that if this macro is not defined, or its value is zero, some | |
c771326b | 1273 | bit-fields may cross more than one alignment boundary. The compiler can |
feca2ed3 JW |
1274 | support such references if there are @samp{insv}, @samp{extv}, and |
1275 | @samp{extzv} insns that can directly reference memory. | |
1276 | ||
c771326b | 1277 | The other known way of making bit-fields work is to define |
feca2ed3 JW |
1278 | @code{STRUCTURE_SIZE_BOUNDARY} as large as @code{BIGGEST_ALIGNMENT}. |
1279 | Then every structure can be accessed with fullwords. | |
1280 | ||
c771326b | 1281 | Unless the machine has bit-field instructions or you define |
feca2ed3 JW |
1282 | @code{STRUCTURE_SIZE_BOUNDARY} that way, you must define |
1283 | @code{PCC_BITFIELD_TYPE_MATTERS} to have a nonzero value. | |
1284 | ||
a3a15b4d | 1285 | If your aim is to make GCC use the same conventions for laying out |
c771326b | 1286 | bit-fields as are used by another compiler, here is how to investigate |
feca2ed3 JW |
1287 | what the other compiler does. Compile and run this program: |
1288 | ||
3ab51846 | 1289 | @smallexample |
feca2ed3 JW |
1290 | struct foo1 |
1291 | @{ | |
1292 | char x; | |
1293 | char :0; | |
1294 | char y; | |
1295 | @}; | |
1296 | ||
1297 | struct foo2 | |
1298 | @{ | |
1299 | char x; | |
1300 | int :0; | |
1301 | char y; | |
1302 | @}; | |
1303 | ||
1304 | main () | |
1305 | @{ | |
1306 | printf ("Size of foo1 is %d\n", | |
1307 | sizeof (struct foo1)); | |
1308 | printf ("Size of foo2 is %d\n", | |
1309 | sizeof (struct foo2)); | |
1310 | exit (0); | |
1311 | @} | |
3ab51846 | 1312 | @end smallexample |
feca2ed3 JW |
1313 | |
1314 | If this prints 2 and 5, then the compiler's behavior is what you would | |
1315 | get from @code{PCC_BITFIELD_TYPE_MATTERS}. | |
a2c4f8e0 | 1316 | @end defmac |
feca2ed3 | 1317 | |
a2c4f8e0 | 1318 | @defmac BITFIELD_NBYTES_LIMITED |
f913c102 AO |
1319 | Like @code{PCC_BITFIELD_TYPE_MATTERS} except that its effect is limited |
1320 | to aligning a bit-field within the structure. | |
a2c4f8e0 | 1321 | @end defmac |
feca2ed3 | 1322 | |
b5bde9ff | 1323 | @deftypefn {Target Hook} bool TARGET_ALIGN_ANON_BITFIELD (void) |
13c1cd82 PB |
1324 | When @code{PCC_BITFIELD_TYPE_MATTERS} is true this hook will determine |
1325 | whether unnamed bitfields affect the alignment of the containing | |
1326 | structure. The hook should return true if the structure should inherit | |
1327 | the alignment requirements of an unnamed bitfield's type. | |
1328 | @end deftypefn | |
1329 | ||
b5bde9ff | 1330 | @deftypefn {Target Hook} bool TARGET_NARROW_VOLATILE_BITFIELD (void) |
c2a64439 PB |
1331 | This target hook should return @code{true} if accesses to volatile bitfields |
1332 | should use the narrowest mode possible. It should return @code{false} if | |
1333 | these accesses should use the bitfield container type. | |
1334 | ||
1335 | The default is @code{!TARGET_STRICT_ALIGN}. | |
1336 | @end deftypefn | |
1337 | ||
a2c4f8e0 | 1338 | @defmac MEMBER_TYPE_FORCES_BLK (@var{field}, @var{mode}) |
31a02448 | 1339 | Return 1 if a structure or array containing @var{field} should be accessed using |
9f6dc500 HPN |
1340 | @code{BLKMODE}. |
1341 | ||
182e515e AH |
1342 | If @var{field} is the only field in the structure, @var{mode} is its |
1343 | mode, otherwise @var{mode} is VOIDmode. @var{mode} is provided in the | |
1344 | case where structures of one field would require the structure's mode to | |
1345 | retain the field's mode. | |
1346 | ||
8d8da227 | 1347 | Normally, this is not needed. |
a2c4f8e0 | 1348 | @end defmac |
9f6dc500 | 1349 | |
a2c4f8e0 | 1350 | @defmac ROUND_TYPE_ALIGN (@var{type}, @var{computed}, @var{specified}) |
0003feb2 VM |
1351 | Define this macro as an expression for the alignment of a type (given |
1352 | by @var{type} as a tree node) if the alignment computed in the usual | |
1353 | way is @var{computed} and the alignment explicitly specified was | |
feca2ed3 JW |
1354 | @var{specified}. |
1355 | ||
1356 | The default is to use @var{specified} if it is larger; otherwise, use | |
1357 | the smaller of @var{computed} and @code{BIGGEST_ALIGNMENT} | |
a2c4f8e0 | 1358 | @end defmac |
feca2ed3 | 1359 | |
a2c4f8e0 | 1360 | @defmac MAX_FIXED_MODE_SIZE |
feca2ed3 JW |
1361 | An integer expression for the size in bits of the largest integer |
1362 | machine mode that should actually be used. All integer machine modes of | |
1363 | this size or smaller can be used for structures and unions with the | |
1364 | appropriate sizes. If this macro is undefined, @code{GET_MODE_BITSIZE | |
1365 | (DImode)} is assumed. | |
a2c4f8e0 | 1366 | @end defmac |
feca2ed3 | 1367 | |
a2c4f8e0 | 1368 | @defmac STACK_SAVEAREA_MODE (@var{save_level}) |
73c8090f | 1369 | If defined, an expression of type @code{enum machine_mode} that |
39403d82 DE |
1370 | specifies the mode of the save area operand of a |
1371 | @code{save_stack_@var{level}} named pattern (@pxref{Standard Names}). | |
1372 | @var{save_level} is one of @code{SAVE_BLOCK}, @code{SAVE_FUNCTION}, or | |
1373 | @code{SAVE_NONLOCAL} and selects which of the three named patterns is | |
1374 | having its mode specified. | |
73c8090f DE |
1375 | |
1376 | You need not define this macro if it always returns @code{Pmode}. You | |
1377 | would most commonly define this macro if the | |
1378 | @code{save_stack_@var{level}} patterns need to support both a 32- and a | |
1379 | 64-bit mode. | |
a2c4f8e0 | 1380 | @end defmac |
73c8090f | 1381 | |
a2c4f8e0 | 1382 | @defmac STACK_SIZE_MODE |
39403d82 DE |
1383 | If defined, an expression of type @code{enum machine_mode} that |
1384 | specifies the mode of the size increment operand of an | |
1385 | @code{allocate_stack} named pattern (@pxref{Standard Names}). | |
1386 | ||
1387 | You need not define this macro if it always returns @code{word_mode}. | |
1388 | You would most commonly define this macro if the @code{allocate_stack} | |
1389 | pattern needs to support both a 32- and a 64-bit mode. | |
a2c4f8e0 | 1390 | @end defmac |
39403d82 | 1391 | |
c7ff6e7a AK |
1392 | @deftypefn {Target Hook} {enum machine_mode} TARGET_LIBGCC_CMP_RETURN_MODE () |
1393 | This target hook should return the mode to be used for the return value | |
1394 | of compare instructions expanded to libgcc calls. If not defined | |
1395 | @code{word_mode} is returned which is the right choice for a majority of | |
1396 | targets. | |
1397 | @end deftypefn | |
1398 | ||
1399 | @deftypefn {Target Hook} {enum machine_mode} TARGET_LIBGCC_SHIFT_COUNT_MODE () | |
1400 | This target hook should return the mode to be used for the shift count operand | |
1401 | of shift instructions expanded to libgcc calls. If not defined | |
1402 | @code{word_mode} is returned which is the right choice for a majority of | |
1403 | targets. | |
1404 | @end deftypefn | |
1405 | ||
a2c4f8e0 | 1406 | @defmac ROUND_TOWARDS_ZERO |
3fcaac1d | 1407 | If defined, this macro should be true if the prevailing rounding |
4099e2c2 | 1408 | mode is towards zero. |
3fcaac1d | 1409 | |
4099e2c2 UW |
1410 | Defining this macro only affects the way @file{libgcc.a} emulates |
1411 | floating-point arithmetic. | |
3fcaac1d RS |
1412 | |
1413 | Not defining this macro is equivalent to returning zero. | |
a2c4f8e0 | 1414 | @end defmac |
3fcaac1d | 1415 | |
a2c4f8e0 | 1416 | @defmac LARGEST_EXPONENT_IS_NORMAL (@var{size}) |
4226378a | 1417 | This macro should return true if floats with @var{size} |
3fcaac1d RS |
1418 | bits do not have a NaN or infinity representation, but use the largest |
1419 | exponent for normal numbers instead. | |
1420 | ||
4099e2c2 | 1421 | Defining this macro only affects the way @file{libgcc.a} emulates |
3fcaac1d RS |
1422 | floating-point arithmetic. |
1423 | ||
1424 | The default definition of this macro returns false for all sizes. | |
a2c4f8e0 | 1425 | @end defmac |
feca2ed3 | 1426 | |
f913c102 AO |
1427 | @deftypefn {Target Hook} bool TARGET_MS_BITFIELD_LAYOUT_P (tree @var{record_type}) |
1428 | This target hook returns @code{true} if bit-fields in the given | |
1429 | @var{record_type} are to be laid out following the rules of Microsoft | |
1430 | Visual C/C++, namely: (i) a bit-field won't share the same storage | |
1431 | unit with the previous bit-field if their underlying types have | |
1432 | different sizes, and the bit-field will be aligned to the highest | |
1433 | alignment of the underlying types of itself and of the previous | |
1434 | bit-field; (ii) a zero-sized bit-field will affect the alignment of | |
1435 | the whole enclosing structure, even if it is unnamed; except that | |
1436 | (iii) a zero-sized bit-field will be disregarded unless it follows | |
6335b0aa | 1437 | another bit-field of nonzero size. If this hook returns @code{true}, |
f913c102 | 1438 | other macros that control bit-field layout are ignored. |
e4850f36 DR |
1439 | |
1440 | When a bit-field is inserted into a packed record, the whole size | |
1441 | of the underlying type is used by one or more same-size adjacent | |
1442 | bit-fields (that is, if its long:3, 32 bits is used in the record, | |
1443 | and any additional adjacent long bit-fields are packed into the same | |
8a36672b JM |
1444 | chunk of 32 bits. However, if the size changes, a new field of that |
1445 | size is allocated). In an unpacked record, this is the same as using | |
e4850f36 DR |
1446 | alignment, but not equivalent when packing. |
1447 | ||
1448 | If both MS bit-fields and @samp{__attribute__((packed))} are used, | |
8a36672b | 1449 | the latter will take precedence. If @samp{__attribute__((packed))} is |
e4850f36 DR |
1450 | used on a single field when MS bit-fields are in use, it will take |
1451 | precedence for that field, but the alignment of the rest of the structure | |
1452 | may affect its placement. | |
f913c102 AO |
1453 | @end deftypefn |
1454 | ||
9a8ce21f JG |
1455 | @deftypefn {Target Hook} {bool} TARGET_DECIMAL_FLOAT_SUPPORTED_P (void) |
1456 | Returns true if the target supports decimal floating point. | |
9a8ce21f JG |
1457 | @end deftypefn |
1458 | ||
ab22c1fa CF |
1459 | @deftypefn {Target Hook} {bool} TARGET_FIXED_POINT_SUPPORTED_P (void) |
1460 | Returns true if the target supports fixed-point arithmetic. | |
1461 | @end deftypefn | |
1462 | ||
e41b2a33 PB |
1463 | @deftypefn {Target Hook} void TARGET_EXPAND_TO_RTL_HOOK (void) |
1464 | This hook is called just before expansion into rtl, allowing the target | |
1465 | to perform additional initializations or analysis before the expansion. | |
1466 | For example, the rs6000 port uses it to allocate a scratch stack slot | |
1467 | for use in copying SDmode values between memory and floating point | |
1468 | registers whenever the function being expanded has any SDmode | |
1469 | usage. | |
1470 | @end deftypefn | |
1471 | ||
1472 | @deftypefn {Target Hook} void TARGET_INSTANTIATE_DECLS (void) | |
1473 | This hook allows the backend to perform additional instantiations on rtl | |
1474 | that are not actually in any insns yet, but will be later. | |
1475 | @end deftypefn | |
1476 | ||
608063c3 JB |
1477 | @deftypefn {Target Hook} {const char *} TARGET_MANGLE_TYPE (tree @var{type}) |
1478 | If your target defines any fundamental types, or any types your target | |
1479 | uses should be mangled differently from the default, define this hook | |
1480 | to return the appropriate encoding for these types as part of a C++ | |
1481 | mangled name. The @var{type} argument is the tree structure representing | |
1482 | the type to be mangled. The hook may be applied to trees which are | |
1483 | not target-specific fundamental types; it should return @code{NULL} | |
1484 | for all such types, as well as arguments it does not recognize. If the | |
1485 | return value is not @code{NULL}, it must point to a statically-allocated | |
1486 | string constant. | |
f18eca82 ZL |
1487 | |
1488 | Target-specific fundamental types might be new fundamental types or | |
1489 | qualified versions of ordinary fundamental types. Encode new | |
1490 | fundamental types as @samp{@w{u @var{n} @var{name}}}, where @var{name} | |
1491 | is the name used for the type in source code, and @var{n} is the | |
1492 | length of @var{name} in decimal. Encode qualified versions of | |
1493 | ordinary types as @samp{@w{U @var{n} @var{name} @var{code}}}, where | |
1494 | @var{name} is the name used for the type qualifier in source code, | |
1495 | @var{n} is the length of @var{name} as above, and @var{code} is the | |
1496 | code used to represent the unqualified version of this type. (See | |
1497 | @code{write_builtin_type} in @file{cp/mangle.c} for the list of | |
1498 | codes.) In both cases the spaces are for clarity; do not include any | |
1499 | spaces in your string. | |
1500 | ||
608063c3 JB |
1501 | This hook is applied to types prior to typedef resolution. If the mangled |
1502 | name for a particular type depends only on that type's main variant, you | |
1503 | can perform typedef resolution yourself using @code{TYPE_MAIN_VARIANT} | |
1504 | before mangling. | |
1505 | ||
f18eca82 ZL |
1506 | The default version of this hook always returns @code{NULL}, which is |
1507 | appropriate for a target that does not define any new fundamental | |
1508 | types. | |
1509 | @end deftypefn | |
1510 | ||
feca2ed3 JW |
1511 | @node Type Layout |
1512 | @section Layout of Source Language Data Types | |
1513 | ||
1514 | These macros define the sizes and other characteristics of the standard | |
1515 | basic data types used in programs being compiled. Unlike the macros in | |
1516 | the previous section, these apply to specific features of C and related | |
1517 | languages, rather than to fundamental aspects of storage layout. | |
1518 | ||
a2c4f8e0 | 1519 | @defmac INT_TYPE_SIZE |
feca2ed3 JW |
1520 | A C expression for the size in bits of the type @code{int} on the |
1521 | target machine. If you don't define this, the default is one word. | |
a2c4f8e0 | 1522 | @end defmac |
feca2ed3 | 1523 | |
a2c4f8e0 | 1524 | @defmac SHORT_TYPE_SIZE |
feca2ed3 JW |
1525 | A C expression for the size in bits of the type @code{short} on the |
1526 | target machine. If you don't define this, the default is half a word. | |
1527 | (If this would be less than one storage unit, it is rounded up to one | |
1528 | unit.) | |
a2c4f8e0 | 1529 | @end defmac |
feca2ed3 | 1530 | |
a2c4f8e0 | 1531 | @defmac LONG_TYPE_SIZE |
feca2ed3 JW |
1532 | A C expression for the size in bits of the type @code{long} on the |
1533 | target machine. If you don't define this, the default is one word. | |
a2c4f8e0 | 1534 | @end defmac |
feca2ed3 | 1535 | |
a2c4f8e0 | 1536 | @defmac ADA_LONG_TYPE_SIZE |
1615c261 | 1537 | On some machines, the size used for the Ada equivalent of the type |
8a36672b | 1538 | @code{long} by a native Ada compiler differs from that used by C@. In |
1615c261 RK |
1539 | that situation, define this macro to be a C expression to be used for |
1540 | the size of that type. If you don't define this, the default is the | |
1541 | value of @code{LONG_TYPE_SIZE}. | |
a2c4f8e0 | 1542 | @end defmac |
1615c261 | 1543 | |
a2c4f8e0 | 1544 | @defmac LONG_LONG_TYPE_SIZE |
feca2ed3 JW |
1545 | A C expression for the size in bits of the type @code{long long} on the |
1546 | target machine. If you don't define this, the default is two | |
047c1c92 | 1547 | words. If you want to support GNU Ada on your machine, the value of this |
feca2ed3 | 1548 | macro must be at least 64. |
a2c4f8e0 | 1549 | @end defmac |
feca2ed3 | 1550 | |
a2c4f8e0 | 1551 | @defmac CHAR_TYPE_SIZE |
feca2ed3 | 1552 | A C expression for the size in bits of the type @code{char} on the |
c294bd99 HPN |
1553 | target machine. If you don't define this, the default is |
1554 | @code{BITS_PER_UNIT}. | |
a2c4f8e0 | 1555 | @end defmac |
feca2ed3 | 1556 | |
a2c4f8e0 | 1557 | @defmac BOOL_TYPE_SIZE |
3d1ad9e5 JM |
1558 | A C expression for the size in bits of the C++ type @code{bool} and |
1559 | C99 type @code{_Bool} on the target machine. If you don't define | |
1560 | this, and you probably shouldn't, the default is @code{CHAR_TYPE_SIZE}. | |
a2c4f8e0 | 1561 | @end defmac |
68eb4fb9 | 1562 | |
a2c4f8e0 | 1563 | @defmac FLOAT_TYPE_SIZE |
feca2ed3 JW |
1564 | A C expression for the size in bits of the type @code{float} on the |
1565 | target machine. If you don't define this, the default is one word. | |
a2c4f8e0 | 1566 | @end defmac |
feca2ed3 | 1567 | |
a2c4f8e0 | 1568 | @defmac DOUBLE_TYPE_SIZE |
feca2ed3 JW |
1569 | A C expression for the size in bits of the type @code{double} on the |
1570 | target machine. If you don't define this, the default is two | |
1571 | words. | |
a2c4f8e0 | 1572 | @end defmac |
feca2ed3 | 1573 | |
a2c4f8e0 | 1574 | @defmac LONG_DOUBLE_TYPE_SIZE |
feca2ed3 JW |
1575 | A C expression for the size in bits of the type @code{long double} on |
1576 | the target machine. If you don't define this, the default is two | |
1577 | words. | |
a2c4f8e0 | 1578 | @end defmac |
feca2ed3 | 1579 | |
325217ed CF |
1580 | @defmac SHORT_FRACT_TYPE_SIZE |
1581 | A C expression for the size in bits of the type @code{short _Fract} on | |
1582 | the target machine. If you don't define this, the default is | |
1583 | @code{BITS_PER_UNIT}. | |
1584 | @end defmac | |
1585 | ||
1586 | @defmac FRACT_TYPE_SIZE | |
1587 | A C expression for the size in bits of the type @code{_Fract} on | |
1588 | the target machine. If you don't define this, the default is | |
1589 | @code{BITS_PER_UNIT * 2}. | |
1590 | @end defmac | |
1591 | ||
1592 | @defmac LONG_FRACT_TYPE_SIZE | |
1593 | A C expression for the size in bits of the type @code{long _Fract} on | |
1594 | the target machine. If you don't define this, the default is | |
1595 | @code{BITS_PER_UNIT * 4}. | |
1596 | @end defmac | |
1597 | ||
1598 | @defmac LONG_LONG_FRACT_TYPE_SIZE | |
1599 | A C expression for the size in bits of the type @code{long long _Fract} on | |
1600 | the target machine. If you don't define this, the default is | |
1601 | @code{BITS_PER_UNIT * 8}. | |
1602 | @end defmac | |
1603 | ||
1604 | @defmac SHORT_ACCUM_TYPE_SIZE | |
1605 | A C expression for the size in bits of the type @code{short _Accum} on | |
1606 | the target machine. If you don't define this, the default is | |
1607 | @code{BITS_PER_UNIT * 2}. | |
1608 | @end defmac | |
1609 | ||
1610 | @defmac ACCUM_TYPE_SIZE | |
1611 | A C expression for the size in bits of the type @code{_Accum} on | |
1612 | the target machine. If you don't define this, the default is | |
1613 | @code{BITS_PER_UNIT * 4}. | |
1614 | @end defmac | |
1615 | ||
1616 | @defmac LONG_ACCUM_TYPE_SIZE | |
1617 | A C expression for the size in bits of the type @code{long _Accum} on | |
1618 | the target machine. If you don't define this, the default is | |
1619 | @code{BITS_PER_UNIT * 8}. | |
1620 | @end defmac | |
1621 | ||
1622 | @defmac LONG_LONG_ACCUM_TYPE_SIZE | |
1623 | A C expression for the size in bits of the type @code{long long _Accum} on | |
1624 | the target machine. If you don't define this, the default is | |
1625 | @code{BITS_PER_UNIT * 16}. | |
1626 | @end defmac | |
1627 | ||
4e9db8b2 SE |
1628 | @defmac LIBGCC2_LONG_DOUBLE_TYPE_SIZE |
1629 | Define this macro if @code{LONG_DOUBLE_TYPE_SIZE} is not constant or | |
1630 | if you want routines in @file{libgcc2.a} for a size other than | |
1631 | @code{LONG_DOUBLE_TYPE_SIZE}. If you don't define this, the | |
1632 | default is @code{LONG_DOUBLE_TYPE_SIZE}. | |
1633 | @end defmac | |
1634 | ||
1635 | @defmac LIBGCC2_HAS_DF_MODE | |
083cad55 | 1636 | Define this macro if neither @code{LIBGCC2_DOUBLE_TYPE_SIZE} nor |
4e9db8b2 SE |
1637 | @code{LIBGCC2_LONG_DOUBLE_TYPE_SIZE} is |
1638 | @code{DFmode} but you want @code{DFmode} routines in @file{libgcc2.a} | |
1639 | anyway. If you don't define this and either @code{LIBGCC2_DOUBLE_TYPE_SIZE} | |
1640 | or @code{LIBGCC2_LONG_DOUBLE_TYPE_SIZE} is 64 then the default is 1, | |
1641 | otherwise it is 0. | |
1642 | @end defmac | |
1643 | ||
1644 | @defmac LIBGCC2_HAS_XF_MODE | |
083cad55 | 1645 | Define this macro if @code{LIBGCC2_LONG_DOUBLE_TYPE_SIZE} is not |
4e9db8b2 SE |
1646 | @code{XFmode} but you want @code{XFmode} routines in @file{libgcc2.a} |
1647 | anyway. If you don't define this and @code{LIBGCC2_LONG_DOUBLE_TYPE_SIZE} | |
1648 | is 80 then the default is 1, otherwise it is 0. | |
1649 | @end defmac | |
1650 | ||
1651 | @defmac LIBGCC2_HAS_TF_MODE | |
083cad55 | 1652 | Define this macro if @code{LIBGCC2_LONG_DOUBLE_TYPE_SIZE} is not |
4e9db8b2 SE |
1653 | @code{TFmode} but you want @code{TFmode} routines in @file{libgcc2.a} |
1654 | anyway. If you don't define this and @code{LIBGCC2_LONG_DOUBLE_TYPE_SIZE} | |
1655 | is 128 then the default is 1, otherwise it is 0. | |
1656 | @end defmac | |
1657 | ||
4a73d865 JM |
1658 | @defmac SF_SIZE |
1659 | @defmacx DF_SIZE | |
1660 | @defmacx XF_SIZE | |
1661 | @defmacx TF_SIZE | |
1662 | Define these macros to be the size in bits of the mantissa of | |
1663 | @code{SFmode}, @code{DFmode}, @code{XFmode} and @code{TFmode} values, | |
1664 | if the defaults in @file{libgcc2.h} are inappropriate. By default, | |
1665 | @code{FLT_MANT_DIG} is used for @code{SF_SIZE}, @code{LDBL_MANT_DIG} | |
1666 | for @code{XF_SIZE} and @code{TF_SIZE}, and @code{DBL_MANT_DIG} or | |
1667 | @code{LDBL_MANT_DIG} for @code{DF_SIZE} according to whether | |
1668 | @code{LIBGCC2_DOUBLE_TYPE_SIZE} or | |
1669 | @code{LIBGCC2_LONG_DOUBLE_TYPE_SIZE} is 64. | |
1670 | @end defmac | |
1671 | ||
a2c4f8e0 | 1672 | @defmac TARGET_FLT_EVAL_METHOD |
d57a4b98 RH |
1673 | A C expression for the value for @code{FLT_EVAL_METHOD} in @file{float.h}, |
1674 | assuming, if applicable, that the floating-point control word is in its | |
1675 | default state. If you do not define this macro the value of | |
1676 | @code{FLT_EVAL_METHOD} will be zero. | |
a2c4f8e0 | 1677 | @end defmac |
aaa2e8ef | 1678 | |
a2c4f8e0 | 1679 | @defmac WIDEST_HARDWARE_FP_SIZE |
e9a25f70 JL |
1680 | A C expression for the size in bits of the widest floating-point format |
1681 | supported by the hardware. If you define this macro, you must specify a | |
1682 | value less than or equal to the value of @code{LONG_DOUBLE_TYPE_SIZE}. | |
1683 | If you do not define this macro, the value of @code{LONG_DOUBLE_TYPE_SIZE} | |
1684 | is the default. | |
a2c4f8e0 | 1685 | @end defmac |
e9a25f70 | 1686 | |
a2c4f8e0 | 1687 | @defmac DEFAULT_SIGNED_CHAR |
feca2ed3 JW |
1688 | An expression whose value is 1 or 0, according to whether the type |
1689 | @code{char} should be signed or unsigned by default. The user can | |
630d3d5a JM |
1690 | always override this default with the options @option{-fsigned-char} |
1691 | and @option{-funsigned-char}. | |
a2c4f8e0 | 1692 | @end defmac |
feca2ed3 | 1693 | |
221ee7c9 KH |
1694 | @deftypefn {Target Hook} bool TARGET_DEFAULT_SHORT_ENUMS (void) |
1695 | This target hook should return true if the compiler should give an | |
1696 | @code{enum} type only as many bytes as it takes to represent the range | |
1697 | of possible values of that type. It should return false if all | |
35afa569 KH |
1698 | @code{enum} types should be allocated like @code{int}. |
1699 | ||
221ee7c9 KH |
1700 | The default is to return false. |
1701 | @end deftypefn | |
35afa569 | 1702 | |
a2c4f8e0 | 1703 | @defmac SIZE_TYPE |
feca2ed3 JW |
1704 | A C expression for a string describing the name of the data type to use |
1705 | for size values. The typedef name @code{size_t} is defined using the | |
1706 | contents of the string. | |
1707 | ||
1708 | The string can contain more than one keyword. If so, separate them with | |
1709 | spaces, and write first any length keyword, then @code{unsigned} if | |
1710 | appropriate, and finally @code{int}. The string must exactly match one | |
1711 | of the data type names defined in the function | |
1712 | @code{init_decl_processing} in the file @file{c-decl.c}. You may not | |
1713 | omit @code{int} or change the order---that would cause the compiler to | |
1714 | crash on startup. | |
1715 | ||
1716 | If you don't define this macro, the default is @code{"long unsigned | |
1717 | int"}. | |
a2c4f8e0 | 1718 | @end defmac |
feca2ed3 | 1719 | |
a2c4f8e0 | 1720 | @defmac PTRDIFF_TYPE |
feca2ed3 JW |
1721 | A C expression for a string describing the name of the data type to use |
1722 | for the result of subtracting two pointers. The typedef name | |
1723 | @code{ptrdiff_t} is defined using the contents of the string. See | |
1724 | @code{SIZE_TYPE} above for more information. | |
1725 | ||
1726 | If you don't define this macro, the default is @code{"long int"}. | |
a2c4f8e0 | 1727 | @end defmac |
feca2ed3 | 1728 | |
a2c4f8e0 | 1729 | @defmac WCHAR_TYPE |
feca2ed3 JW |
1730 | A C expression for a string describing the name of the data type to use |
1731 | for wide characters. The typedef name @code{wchar_t} is defined using | |
1732 | the contents of the string. See @code{SIZE_TYPE} above for more | |
1733 | information. | |
1734 | ||
1735 | If you don't define this macro, the default is @code{"int"}. | |
a2c4f8e0 | 1736 | @end defmac |
feca2ed3 | 1737 | |
a2c4f8e0 | 1738 | @defmac WCHAR_TYPE_SIZE |
feca2ed3 JW |
1739 | A C expression for the size in bits of the data type for wide |
1740 | characters. This is used in @code{cpp}, which cannot make use of | |
1741 | @code{WCHAR_TYPE}. | |
a2c4f8e0 | 1742 | @end defmac |
feca2ed3 | 1743 | |
a2c4f8e0 | 1744 | @defmac WINT_TYPE |
1a67c7d3 JL |
1745 | A C expression for a string describing the name of the data type to |
1746 | use for wide characters passed to @code{printf} and returned from | |
1747 | @code{getwc}. The typedef name @code{wint_t} is defined using the | |
1748 | contents of the string. See @code{SIZE_TYPE} above for more | |
1749 | information. | |
1750 | ||
1751 | If you don't define this macro, the default is @code{"unsigned int"}. | |
a2c4f8e0 | 1752 | @end defmac |
1a67c7d3 | 1753 | |
a2c4f8e0 | 1754 | @defmac INTMAX_TYPE |
b15ad712 JM |
1755 | A C expression for a string describing the name of the data type that |
1756 | can represent any value of any standard or extended signed integer type. | |
1757 | The typedef name @code{intmax_t} is defined using the contents of the | |
1758 | string. See @code{SIZE_TYPE} above for more information. | |
1759 | ||
1760 | If you don't define this macro, the default is the first of | |
1761 | @code{"int"}, @code{"long int"}, or @code{"long long int"} that has as | |
1762 | much precision as @code{long long int}. | |
a2c4f8e0 | 1763 | @end defmac |
b15ad712 | 1764 | |
a2c4f8e0 | 1765 | @defmac UINTMAX_TYPE |
b15ad712 JM |
1766 | A C expression for a string describing the name of the data type that |
1767 | can represent any value of any standard or extended unsigned integer | |
1768 | type. The typedef name @code{uintmax_t} is defined using the contents | |
1769 | of the string. See @code{SIZE_TYPE} above for more information. | |
1770 | ||
1771 | If you don't define this macro, the default is the first of | |
1772 | @code{"unsigned int"}, @code{"long unsigned int"}, or @code{"long long | |
1773 | unsigned int"} that has as much precision as @code{long long unsigned | |
1774 | int}. | |
a2c4f8e0 | 1775 | @end defmac |
b15ad712 | 1776 | |
207bf79d JM |
1777 | @defmac SIG_ATOMIC_TYPE |
1778 | @defmacx INT8_TYPE | |
1779 | @defmacx INT16_TYPE | |
1780 | @defmacx INT32_TYPE | |
1781 | @defmacx INT64_TYPE | |
1782 | @defmacx UINT8_TYPE | |
1783 | @defmacx UINT16_TYPE | |
1784 | @defmacx UINT32_TYPE | |
1785 | @defmacx UINT64_TYPE | |
1786 | @defmacx INT_LEAST8_TYPE | |
1787 | @defmacx INT_LEAST16_TYPE | |
1788 | @defmacx INT_LEAST32_TYPE | |
1789 | @defmacx INT_LEAST64_TYPE | |
1790 | @defmacx UINT_LEAST8_TYPE | |
1791 | @defmacx UINT_LEAST16_TYPE | |
1792 | @defmacx UINT_LEAST32_TYPE | |
1793 | @defmacx UINT_LEAST64_TYPE | |
1794 | @defmacx INT_FAST8_TYPE | |
1795 | @defmacx INT_FAST16_TYPE | |
1796 | @defmacx INT_FAST32_TYPE | |
1797 | @defmacx INT_FAST64_TYPE | |
1798 | @defmacx UINT_FAST8_TYPE | |
1799 | @defmacx UINT_FAST16_TYPE | |
1800 | @defmacx UINT_FAST32_TYPE | |
1801 | @defmacx UINT_FAST64_TYPE | |
1802 | @defmacx INTPTR_TYPE | |
1803 | @defmacx UINTPTR_TYPE | |
1804 | C expressions for the standard types @code{sig_atomic_t}, | |
1805 | @code{int8_t}, @code{int16_t}, @code{int32_t}, @code{int64_t}, | |
1806 | @code{uint8_t}, @code{uint16_t}, @code{uint32_t}, @code{uint64_t}, | |
1807 | @code{int_least8_t}, @code{int_least16_t}, @code{int_least32_t}, | |
1808 | @code{int_least64_t}, @code{uint_least8_t}, @code{uint_least16_t}, | |
1809 | @code{uint_least32_t}, @code{uint_least64_t}, @code{int_fast8_t}, | |
1810 | @code{int_fast16_t}, @code{int_fast32_t}, @code{int_fast64_t}, | |
1811 | @code{uint_fast8_t}, @code{uint_fast16_t}, @code{uint_fast32_t}, | |
1812 | @code{uint_fast64_t}, @code{intptr_t}, and @code{uintptr_t}. See | |
1813 | @code{SIZE_TYPE} above for more information. | |
1814 | ||
1815 | If any of these macros evaluates to a null pointer, the corresponding | |
1816 | type is not supported; if GCC is configured to provide | |
1817 | @code{<stdint.h>} in such a case, the header provided may not conform | |
1818 | to C99, depending on the type in question. The defaults for all of | |
1819 | these macros are null pointers. | |
1820 | @end defmac | |
1821 | ||
a2c4f8e0 | 1822 | @defmac TARGET_PTRMEMFUNC_VBIT_LOCATION |
f3c55c97 AO |
1823 | The C++ compiler represents a pointer-to-member-function with a struct |
1824 | that looks like: | |
1825 | ||
3ab51846 | 1826 | @smallexample |
f3c55c97 AO |
1827 | struct @{ |
1828 | union @{ | |
1829 | void (*fn)(); | |
1830 | ptrdiff_t vtable_index; | |
1831 | @}; | |
1832 | ptrdiff_t delta; | |
1833 | @}; | |
3ab51846 | 1834 | @end smallexample |
f3c55c97 AO |
1835 | |
1836 | @noindent | |
1837 | The C++ compiler must use one bit to indicate whether the function that | |
1838 | will be called through a pointer-to-member-function is virtual. | |
1839 | Normally, we assume that the low-order bit of a function pointer must | |
1840 | always be zero. Then, by ensuring that the vtable_index is odd, we can | |
1841 | distinguish which variant of the union is in use. But, on some | |
1842 | platforms function pointers can be odd, and so this doesn't work. In | |
1843 | that case, we use the low-order bit of the @code{delta} field, and shift | |
1844 | the remainder of the @code{delta} field to the left. | |
1845 | ||
1846 | GCC will automatically make the right selection about where to store | |
1847 | this bit using the @code{FUNCTION_BOUNDARY} setting for your platform. | |
1848 | However, some platforms such as ARM/Thumb have @code{FUNCTION_BOUNDARY} | |
1849 | set such that functions always start at even addresses, but the lowest | |
1850 | bit of pointers to functions indicate whether the function at that | |
1851 | address is in ARM or Thumb mode. If this is the case of your | |
1852 | architecture, you should define this macro to | |
1853 | @code{ptrmemfunc_vbit_in_delta}. | |
1854 | ||
1855 | In general, you should not have to define this macro. On architectures | |
1856 | in which function addresses are always even, according to | |
1857 | @code{FUNCTION_BOUNDARY}, GCC will automatically define this macro to | |
1858 | @code{ptrmemfunc_vbit_in_pfn}. | |
a2c4f8e0 | 1859 | @end defmac |
67231816 | 1860 | |
a2c4f8e0 | 1861 | @defmac TARGET_VTABLE_USES_DESCRIPTORS |
67231816 | 1862 | Normally, the C++ compiler uses function pointers in vtables. This |
f282ffb3 | 1863 | macro allows the target to change to use ``function descriptors'' |
67231816 RH |
1864 | instead. Function descriptors are found on targets for whom a |
1865 | function pointer is actually a small data structure. Normally the | |
f282ffb3 | 1866 | data structure consists of the actual code address plus a data |
67231816 RH |
1867 | pointer to which the function's data is relative. |
1868 | ||
1869 | If vtables are used, the value of this macro should be the number | |
1870 | of words that the function descriptor occupies. | |
a2c4f8e0 | 1871 | @end defmac |
a6f5e048 | 1872 | |
a2c4f8e0 | 1873 | @defmac TARGET_VTABLE_ENTRY_ALIGN |
a6f5e048 RH |
1874 | By default, the vtable entries are void pointers, the so the alignment |
1875 | is the same as pointer alignment. The value of this macro specifies | |
1876 | the alignment of the vtable entry in bits. It should be defined only | |
1877 | when special alignment is necessary. */ | |
a2c4f8e0 | 1878 | @end defmac |
a6f5e048 | 1879 | |
a2c4f8e0 | 1880 | @defmac TARGET_VTABLE_DATA_ENTRY_DISTANCE |
a6f5e048 RH |
1881 | There are a few non-descriptor entries in the vtable at offsets below |
1882 | zero. If these entries must be padded (say, to preserve the alignment | |
1883 | specified by @code{TARGET_VTABLE_ENTRY_ALIGN}), set this to the number | |
1884 | of words in each data entry. | |
a2c4f8e0 | 1885 | @end defmac |
b2b263e1 | 1886 | |
feca2ed3 JW |
1887 | @node Registers |
1888 | @section Register Usage | |
1889 | @cindex register usage | |
1890 | ||
1891 | This section explains how to describe what registers the target machine | |
1892 | has, and how (in general) they can be used. | |
1893 | ||
1894 | The description of which registers a specific instruction can use is | |
1895 | done with register classes; see @ref{Register Classes}. For information | |
1896 | on using registers to access a stack frame, see @ref{Frame Registers}. | |
1897 | For passing values in registers, see @ref{Register Arguments}. | |
1898 | For returning values in registers, see @ref{Scalar Return}. | |
1899 | ||
1900 | @menu | |
6ccde948 RW |
1901 | * Register Basics:: Number and kinds of registers. |
1902 | * Allocation Order:: Order in which registers are allocated. | |
1903 | * Values in Registers:: What kinds of values each reg can hold. | |
1904 | * Leaf Functions:: Renumbering registers for leaf functions. | |
1905 | * Stack Registers:: Handling a register stack such as 80387. | |
feca2ed3 JW |
1906 | @end menu |
1907 | ||
1908 | @node Register Basics | |
1909 | @subsection Basic Characteristics of Registers | |
1910 | ||
1911 | @c prevent bad page break with this line | |
1912 | Registers have various characteristics. | |
1913 | ||
a2c4f8e0 | 1914 | @defmac FIRST_PSEUDO_REGISTER |
feca2ed3 JW |
1915 | Number of hardware registers known to the compiler. They receive |
1916 | numbers 0 through @code{FIRST_PSEUDO_REGISTER-1}; thus, the first | |
1917 | pseudo register's number really is assigned the number | |
1918 | @code{FIRST_PSEUDO_REGISTER}. | |
a2c4f8e0 | 1919 | @end defmac |
feca2ed3 | 1920 | |
a2c4f8e0 | 1921 | @defmac FIXED_REGISTERS |
feca2ed3 JW |
1922 | @cindex fixed register |
1923 | An initializer that says which registers are used for fixed purposes | |
1924 | all throughout the compiled code and are therefore not available for | |
1925 | general allocation. These would include the stack pointer, the frame | |
1926 | pointer (except on machines where that can be used as a general | |
1927 | register when no frame pointer is needed), the program counter on | |
1928 | machines where that is considered one of the addressable registers, | |
1929 | and any other numbered register with a standard use. | |
1930 | ||
1931 | This information is expressed as a sequence of numbers, separated by | |
1932 | commas and surrounded by braces. The @var{n}th number is 1 if | |
1933 | register @var{n} is fixed, 0 otherwise. | |
1934 | ||
1935 | The table initialized from this macro, and the table initialized by | |
1936 | the following one, may be overridden at run time either automatically, | |
1937 | by the actions of the macro @code{CONDITIONAL_REGISTER_USAGE}, or by | |
630d3d5a JM |
1938 | the user with the command options @option{-ffixed-@var{reg}}, |
1939 | @option{-fcall-used-@var{reg}} and @option{-fcall-saved-@var{reg}}. | |
a2c4f8e0 | 1940 | @end defmac |
feca2ed3 | 1941 | |
a2c4f8e0 | 1942 | @defmac CALL_USED_REGISTERS |
feca2ed3 JW |
1943 | @cindex call-used register |
1944 | @cindex call-clobbered register | |
1945 | @cindex call-saved register | |
1946 | Like @code{FIXED_REGISTERS} but has 1 for each register that is | |
1947 | clobbered (in general) by function calls as well as for fixed | |
1948 | registers. This macro therefore identifies the registers that are not | |
1949 | available for general allocation of values that must live across | |
1950 | function calls. | |
1951 | ||
1952 | If a register has 0 in @code{CALL_USED_REGISTERS}, the compiler | |
1953 | automatically saves it on function entry and restores it on function | |
1954 | exit, if the register is used within the function. | |
a2c4f8e0 | 1955 | @end defmac |
feca2ed3 | 1956 | |
a2c4f8e0 | 1957 | @defmac CALL_REALLY_USED_REGISTERS |
fc1296b7 AM |
1958 | @cindex call-used register |
1959 | @cindex call-clobbered register | |
1960 | @cindex call-saved register | |
f282ffb3 JM |
1961 | Like @code{CALL_USED_REGISTERS} except this macro doesn't require |
1962 | that the entire set of @code{FIXED_REGISTERS} be included. | |
fc1296b7 | 1963 | (@code{CALL_USED_REGISTERS} must be a superset of @code{FIXED_REGISTERS}). |
f282ffb3 | 1964 | This macro is optional. If not specified, it defaults to the value |
fc1296b7 | 1965 | of @code{CALL_USED_REGISTERS}. |
a2c4f8e0 | 1966 | @end defmac |
fc1296b7 | 1967 | |
a2c4f8e0 | 1968 | @defmac HARD_REGNO_CALL_PART_CLOBBERED (@var{regno}, @var{mode}) |
1e326708 MH |
1969 | @cindex call-used register |
1970 | @cindex call-clobbered register | |
1971 | @cindex call-saved register | |
df2a54e9 | 1972 | A C expression that is nonzero if it is not permissible to store a |
1e326708 MH |
1973 | value of mode @var{mode} in hard register number @var{regno} across a |
1974 | call without some part of it being clobbered. For most machines this | |
1975 | macro need not be defined. It is only required for machines that do not | |
1976 | preserve the entire contents of a register across a call. | |
a2c4f8e0 | 1977 | @end defmac |
1e326708 | 1978 | |
feca2ed3 JW |
1979 | @findex fixed_regs |
1980 | @findex call_used_regs | |
a2c4f8e0 ZW |
1981 | @findex global_regs |
1982 | @findex reg_names | |
1983 | @findex reg_class_contents | |
1984 | @defmac CONDITIONAL_REGISTER_USAGE | |
055177dc NC |
1985 | Zero or more C statements that may conditionally modify five variables |
1986 | @code{fixed_regs}, @code{call_used_regs}, @code{global_regs}, | |
c237e94a ZW |
1987 | @code{reg_names}, and @code{reg_class_contents}, to take into account |
1988 | any dependence of these register sets on target flags. The first three | |
1989 | of these are of type @code{char []} (interpreted as Boolean vectors). | |
1990 | @code{global_regs} is a @code{const char *[]}, and | |
1991 | @code{reg_class_contents} is a @code{HARD_REG_SET}. Before the macro is | |
1992 | called, @code{fixed_regs}, @code{call_used_regs}, | |
1993 | @code{reg_class_contents}, and @code{reg_names} have been initialized | |
055177dc | 1994 | from @code{FIXED_REGISTERS}, @code{CALL_USED_REGISTERS}, |
c237e94a | 1995 | @code{REG_CLASS_CONTENTS}, and @code{REGISTER_NAMES}, respectively. |
630d3d5a | 1996 | @code{global_regs} has been cleared, and any @option{-ffixed-@var{reg}}, |
c237e94a ZW |
1997 | @option{-fcall-used-@var{reg}} and @option{-fcall-saved-@var{reg}} |
1998 | command options have been applied. | |
feca2ed3 JW |
1999 | |
2000 | You need not define this macro if it has no work to do. | |
2001 | ||
2002 | @cindex disabling certain registers | |
2003 | @cindex controlling register usage | |
2004 | If the usage of an entire class of registers depends on the target | |
2005 | flags, you may indicate this to GCC by using this macro to modify | |
2006 | @code{fixed_regs} and @code{call_used_regs} to 1 for each of the | |
161d7b59 | 2007 | registers in the classes which should not be used by GCC@. Also define |
97488870 R |
2008 | the macro @code{REG_CLASS_FROM_LETTER} / @code{REG_CLASS_FROM_CONSTRAINT} |
2009 | to return @code{NO_REGS} if it | |
feca2ed3 JW |
2010 | is called with a letter for a class that shouldn't be used. |
2011 | ||
2012 | (However, if this class is not included in @code{GENERAL_REGS} and all | |
2013 | of the insn patterns whose constraints permit this class are | |
2014 | controlled by target switches, then GCC will automatically avoid using | |
2015 | these registers when the target switches are opposed to them.) | |
a2c4f8e0 | 2016 | @end defmac |
feca2ed3 | 2017 | |
a2c4f8e0 | 2018 | @defmac INCOMING_REGNO (@var{out}) |
feca2ed3 JW |
2019 | Define this macro if the target machine has register windows. This C |
2020 | expression returns the register number as seen by the called function | |
2021 | corresponding to the register number @var{out} as seen by the calling | |
2022 | function. Return @var{out} if register number @var{out} is not an | |
2023 | outbound register. | |
a2c4f8e0 | 2024 | @end defmac |
feca2ed3 | 2025 | |
a2c4f8e0 | 2026 | @defmac OUTGOING_REGNO (@var{in}) |
feca2ed3 JW |
2027 | Define this macro if the target machine has register windows. This C |
2028 | expression returns the register number as seen by the calling function | |
2029 | corresponding to the register number @var{in} as seen by the called | |
2030 | function. Return @var{in} if register number @var{in} is not an inbound | |
2031 | register. | |
a2c4f8e0 | 2032 | @end defmac |
feca2ed3 | 2033 | |
a2c4f8e0 | 2034 | @defmac LOCAL_REGNO (@var{regno}) |
fa80e43d JL |
2035 | Define this macro if the target machine has register windows. This C |
2036 | expression returns true if the register is call-saved but is in the | |
2037 | register window. Unlike most call-saved registers, such registers | |
2038 | need not be explicitly restored on function exit or during non-local | |
2039 | gotos. | |
a2c4f8e0 | 2040 | @end defmac |
fa80e43d | 2041 | |
a2c4f8e0 | 2042 | @defmac PC_REGNUM |
feca2ed3 JW |
2043 | If the program counter has a register number, define this as that |
2044 | register number. Otherwise, do not define it. | |
a2c4f8e0 | 2045 | @end defmac |
feca2ed3 JW |
2046 | |
2047 | @node Allocation Order | |
2048 | @subsection Order of Allocation of Registers | |
2049 | @cindex order of register allocation | |
2050 | @cindex register allocation order | |
2051 | ||
2052 | @c prevent bad page break with this line | |
2053 | Registers are allocated in order. | |
2054 | ||
a2c4f8e0 | 2055 | @defmac REG_ALLOC_ORDER |
feca2ed3 | 2056 | If defined, an initializer for a vector of integers, containing the |
a3a15b4d | 2057 | numbers of hard registers in the order in which GCC should prefer |
feca2ed3 JW |
2058 | to use them (from most preferred to least). |
2059 | ||
2060 | If this macro is not defined, registers are used lowest numbered first | |
2061 | (all else being equal). | |
2062 | ||
2063 | One use of this macro is on machines where the highest numbered | |
2064 | registers must always be saved and the save-multiple-registers | |
2065 | instruction supports only sequences of consecutive registers. On such | |
2066 | machines, define @code{REG_ALLOC_ORDER} to be an initializer that lists | |
956d6950 | 2067 | the highest numbered allocable register first. |
a2c4f8e0 | 2068 | @end defmac |
feca2ed3 | 2069 | |
a2c4f8e0 | 2070 | @defmac ORDER_REGS_FOR_LOCAL_ALLOC |
feca2ed3 JW |
2071 | A C statement (sans semicolon) to choose the order in which to allocate |
2072 | hard registers for pseudo-registers local to a basic block. | |
2073 | ||
2074 | Store the desired register order in the array @code{reg_alloc_order}. | |
2075 | Element 0 should be the register to allocate first; element 1, the next | |
2076 | register; and so on. | |
2077 | ||
2078 | The macro body should not assume anything about the contents of | |
2079 | @code{reg_alloc_order} before execution of the macro. | |
2080 | ||
2081 | On most machines, it is not necessary to define this macro. | |
a2c4f8e0 | 2082 | @end defmac |
feca2ed3 | 2083 | |
058e97ec VM |
2084 | @defmac IRA_HARD_REGNO_ADD_COST_MULTIPLIER (@var{regno}) |
2085 | In some case register allocation order is not enough for the | |
2086 | Integrated Register Allocator (@acronym{IRA}) to generate a good code. | |
2087 | If this macro is defined, it should return a floating point value | |
2088 | based on @var{regno}. The cost of using @var{regno} for a pseudo will | |
2089 | be increased by approximately the pseudo's usage frequency times the | |
2090 | value returned by this macro. Not defining this macro is equivalent | |
2091 | to having it always return @code{0.0}. | |
2092 | ||
2093 | On most machines, it is not necessary to define this macro. | |
2094 | @end defmac | |
2095 | ||
feca2ed3 JW |
2096 | @node Values in Registers |
2097 | @subsection How Values Fit in Registers | |
2098 | ||
2099 | This section discusses the macros that describe which kinds of values | |
2100 | (specifically, which machine modes) each register can hold, and how many | |
2101 | consecutive registers are needed for a given mode. | |
2102 | ||
a2c4f8e0 | 2103 | @defmac HARD_REGNO_NREGS (@var{regno}, @var{mode}) |
feca2ed3 JW |
2104 | A C expression for the number of consecutive hard registers, starting |
2105 | at register number @var{regno}, required to hold a value of mode | |
79e168da DD |
2106 | @var{mode}. This macro must never return zero, even if a register |
2107 | cannot hold the requested mode - indicate that with HARD_REGNO_MODE_OK | |
2108 | and/or CANNOT_CHANGE_MODE_CLASS instead. | |
feca2ed3 JW |
2109 | |
2110 | On a machine where all registers are exactly one word, a suitable | |
2111 | definition of this macro is | |
2112 | ||
2113 | @smallexample | |
2114 | #define HARD_REGNO_NREGS(REGNO, MODE) \ | |
2115 | ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) \ | |
32bd3974 | 2116 | / UNITS_PER_WORD) |
feca2ed3 | 2117 | @end smallexample |
a2c4f8e0 | 2118 | @end defmac |
feca2ed3 | 2119 | |
8521c414 JM |
2120 | @defmac HARD_REGNO_NREGS_HAS_PADDING (@var{regno}, @var{mode}) |
2121 | A C expression that is nonzero if a value of mode @var{mode}, stored | |
2122 | in memory, ends with padding that causes it to take up more space than | |
2123 | in registers starting at register number @var{regno} (as determined by | |
2124 | multiplying GCC's notion of the size of the register when containing | |
2125 | this mode by the number of registers returned by | |
2126 | @code{HARD_REGNO_NREGS}). By default this is zero. | |
2127 | ||
2128 | For example, if a floating-point value is stored in three 32-bit | |
2129 | registers but takes up 128 bits in memory, then this would be | |
2130 | nonzero. | |
2131 | ||
2132 | This macros only needs to be defined if there are cases where | |
f1f4e530 | 2133 | @code{subreg_get_info} |
8521c414 JM |
2134 | would otherwise wrongly determine that a @code{subreg} can be |
2135 | represented by an offset to the register number, when in fact such a | |
2136 | @code{subreg} would contain some of the padding not stored in | |
2137 | registers and so not be representable. | |
2138 | @end defmac | |
2139 | ||
2140 | @defmac HARD_REGNO_NREGS_WITH_PADDING (@var{regno}, @var{mode}) | |
2141 | For values of @var{regno} and @var{mode} for which | |
2142 | @code{HARD_REGNO_NREGS_HAS_PADDING} returns nonzero, a C expression | |
2143 | returning the greater number of registers required to hold the value | |
2144 | including any padding. In the example above, the value would be four. | |
2145 | @end defmac | |
2146 | ||
ca0b6e3b EB |
2147 | @defmac REGMODE_NATURAL_SIZE (@var{mode}) |
2148 | Define this macro if the natural size of registers that hold values | |
2149 | of mode @var{mode} is not the word size. It is a C expression that | |
2150 | should give the natural size in bytes for the specified mode. It is | |
2151 | used by the register allocator to try to optimize its results. This | |
2152 | happens for example on SPARC 64-bit where the natural size of | |
2153 | floating-point registers is still 32-bit. | |
2154 | @end defmac | |
2155 | ||
a2c4f8e0 | 2156 | @defmac HARD_REGNO_MODE_OK (@var{regno}, @var{mode}) |
feca2ed3 JW |
2157 | A C expression that is nonzero if it is permissible to store a value |
2158 | of mode @var{mode} in hard register number @var{regno} (or in several | |
2159 | registers starting with that one). For a machine where all registers | |
2160 | are equivalent, a suitable definition is | |
2161 | ||
2162 | @smallexample | |
2163 | #define HARD_REGNO_MODE_OK(REGNO, MODE) 1 | |
2164 | @end smallexample | |
2165 | ||
e9a25f70 JL |
2166 | You need not include code to check for the numbers of fixed registers, |
2167 | because the allocation mechanism considers them to be always occupied. | |
feca2ed3 JW |
2168 | |
2169 | @cindex register pairs | |
2170 | On some machines, double-precision values must be kept in even/odd | |
e9a25f70 JL |
2171 | register pairs. You can implement that by defining this macro to reject |
2172 | odd register numbers for such modes. | |
feca2ed3 JW |
2173 | |
2174 | The minimum requirement for a mode to be OK in a register is that the | |
2175 | @samp{mov@var{mode}} instruction pattern support moves between the | |
e9a25f70 JL |
2176 | register and other hard register in the same class and that moving a |
2177 | value into the register and back out not alter it. | |
feca2ed3 | 2178 | |
e9a25f70 JL |
2179 | Since the same instruction used to move @code{word_mode} will work for |
2180 | all narrower integer modes, it is not necessary on any machine for | |
feca2ed3 JW |
2181 | @code{HARD_REGNO_MODE_OK} to distinguish between these modes, provided |
2182 | you define patterns @samp{movhi}, etc., to take advantage of this. This | |
2183 | is useful because of the interaction between @code{HARD_REGNO_MODE_OK} | |
2184 | and @code{MODES_TIEABLE_P}; it is very desirable for all integer modes | |
2185 | to be tieable. | |
2186 | ||
2187 | Many machines have special registers for floating point arithmetic. | |
2188 | Often people assume that floating point machine modes are allowed only | |
2189 | in floating point registers. This is not true. Any registers that | |
2190 | can hold integers can safely @emph{hold} a floating point machine | |
2191 | mode, whether or not floating arithmetic can be done on it in those | |
2192 | registers. Integer move instructions can be used to move the values. | |
2193 | ||
2194 | On some machines, though, the converse is true: fixed-point machine | |
2195 | modes may not go in floating registers. This is true if the floating | |
2196 | registers normalize any value stored in them, because storing a | |
2197 | non-floating value there would garble it. In this case, | |
2198 | @code{HARD_REGNO_MODE_OK} should reject fixed-point machine modes in | |
2199 | floating registers. But if the floating registers do not automatically | |
2200 | normalize, if you can store any bit pattern in one and retrieve it | |
2201 | unchanged without a trap, then any machine mode may go in a floating | |
2202 | register, so you can define this macro to say so. | |
2203 | ||
2204 | The primary significance of special floating registers is rather that | |
2205 | they are the registers acceptable in floating point arithmetic | |
2206 | instructions. However, this is of no concern to | |
2207 | @code{HARD_REGNO_MODE_OK}. You handle it by writing the proper | |
2208 | constraints for those instructions. | |
2209 | ||
2210 | On some machines, the floating registers are especially slow to access, | |
2211 | so that it is better to store a value in a stack frame than in such a | |
2212 | register if floating point arithmetic is not being done. As long as the | |
2213 | floating registers are not in class @code{GENERAL_REGS}, they will not | |
2214 | be used unless some pattern's constraint asks for one. | |
a2c4f8e0 | 2215 | @end defmac |
feca2ed3 | 2216 | |
150c9fe8 KH |
2217 | @defmac HARD_REGNO_RENAME_OK (@var{from}, @var{to}) |
2218 | A C expression that is nonzero if it is OK to rename a hard register | |
2219 | @var{from} to another hard register @var{to}. | |
2220 | ||
2221 | One common use of this macro is to prevent renaming of a register to | |
2222 | another register that is not saved by a prologue in an interrupt | |
2223 | handler. | |
2224 | ||
2225 | The default is always nonzero. | |
2226 | @end defmac | |
2227 | ||
a2c4f8e0 | 2228 | @defmac MODES_TIEABLE_P (@var{mode1}, @var{mode2}) |
e9a25f70 | 2229 | A C expression that is nonzero if a value of mode |
956d6950 | 2230 | @var{mode1} is accessible in mode @var{mode2} without copying. |
feca2ed3 JW |
2231 | |
2232 | If @code{HARD_REGNO_MODE_OK (@var{r}, @var{mode1})} and | |
e9a25f70 JL |
2233 | @code{HARD_REGNO_MODE_OK (@var{r}, @var{mode2})} are always the same for |
2234 | any @var{r}, then @code{MODES_TIEABLE_P (@var{mode1}, @var{mode2})} | |
2235 | should be nonzero. If they differ for any @var{r}, you should define | |
2236 | this macro to return zero unless some other mechanism ensures the | |
956d6950 | 2237 | accessibility of the value in a narrower mode. |
e9a25f70 JL |
2238 | |
2239 | You should define this macro to return nonzero in as many cases as | |
a3a15b4d | 2240 | possible since doing so will allow GCC to perform better register |
e9a25f70 | 2241 | allocation. |
a2c4f8e0 | 2242 | @end defmac |
7506f491 | 2243 | |
dbc42c44 AS |
2244 | @deftypefn {Target Hook} bool TARGET_HARD_REGNO_SCRATCH_OK (unsigned int @var{regno}) |
2245 | This target hook should return @code{true} if it is OK to use a hard register | |
2246 | @var{regno} as scratch reg in peephole2. | |
2247 | ||
2248 | One common use of this macro is to prevent using of a register that | |
2249 | is not saved by a prologue in an interrupt handler. | |
2250 | ||
2251 | The default version of this hook always returns @code{true}. | |
2252 | @end deftypefn | |
2253 | ||
a2c4f8e0 | 2254 | @defmac AVOID_CCMODE_COPIES |
7506f491 | 2255 | Define this macro if the compiler should avoid copies to/from @code{CCmode} |
a89608cb | 2256 | registers. You should only define this macro if support for copying to/from |
7506f491 | 2257 | @code{CCmode} is incomplete. |
a2c4f8e0 | 2258 | @end defmac |
feca2ed3 JW |
2259 | |
2260 | @node Leaf Functions | |
2261 | @subsection Handling Leaf Functions | |
2262 | ||
2263 | @cindex leaf functions | |
2264 | @cindex functions, leaf | |
2265 | On some machines, a leaf function (i.e., one which makes no calls) can run | |
2266 | more efficiently if it does not make its own register window. Often this | |
2267 | means it is required to receive its arguments in the registers where they | |
2268 | are passed by the caller, instead of the registers where they would | |
2269 | normally arrive. | |
2270 | ||
2271 | The special treatment for leaf functions generally applies only when | |
2272 | other conditions are met; for example, often they may use only those | |
2273 | registers for its own variables and temporaries. We use the term ``leaf | |
2274 | function'' to mean a function that is suitable for this special | |
2275 | handling, so that functions with no calls are not necessarily ``leaf | |
2276 | functions''. | |
2277 | ||
a3a15b4d | 2278 | GCC assigns register numbers before it knows whether the function is |
feca2ed3 JW |
2279 | suitable for leaf function treatment. So it needs to renumber the |
2280 | registers in order to output a leaf function. The following macros | |
2281 | accomplish this. | |
2282 | ||
a2c4f8e0 | 2283 | @defmac LEAF_REGISTERS |
7d167afd | 2284 | Name of a char vector, indexed by hard register number, which |
feca2ed3 JW |
2285 | contains 1 for a register that is allowable in a candidate for leaf |
2286 | function treatment. | |
2287 | ||
2288 | If leaf function treatment involves renumbering the registers, then the | |
2289 | registers marked here should be the ones before renumbering---those that | |
a3a15b4d | 2290 | GCC would ordinarily allocate. The registers which will actually be |
feca2ed3 JW |
2291 | used in the assembler code, after renumbering, should not be marked with 1 |
2292 | in this vector. | |
2293 | ||
2294 | Define this macro only if the target machine offers a way to optimize | |
2295 | the treatment of leaf functions. | |
a2c4f8e0 | 2296 | @end defmac |
feca2ed3 | 2297 | |
a2c4f8e0 | 2298 | @defmac LEAF_REG_REMAP (@var{regno}) |
feca2ed3 JW |
2299 | A C expression whose value is the register number to which @var{regno} |
2300 | should be renumbered, when a function is treated as a leaf function. | |
2301 | ||
2302 | If @var{regno} is a register number which should not appear in a leaf | |
630d3d5a | 2303 | function before renumbering, then the expression should yield @minus{}1, which |
feca2ed3 JW |
2304 | will cause the compiler to abort. |
2305 | ||
2306 | Define this macro only if the target machine offers a way to optimize the | |
2307 | treatment of leaf functions, and registers need to be renumbered to do | |
2308 | this. | |
a2c4f8e0 | 2309 | @end defmac |
feca2ed3 | 2310 | |
54ff41b7 JW |
2311 | @findex current_function_is_leaf |
2312 | @findex current_function_uses_only_leaf_regs | |
c237e94a ZW |
2313 | @code{TARGET_ASM_FUNCTION_PROLOGUE} and |
2314 | @code{TARGET_ASM_FUNCTION_EPILOGUE} must usually treat leaf functions | |
2315 | specially. They can test the C variable @code{current_function_is_leaf} | |
2316 | which is nonzero for leaf functions. @code{current_function_is_leaf} is | |
2317 | set prior to local register allocation and is valid for the remaining | |
08c148a8 NB |
2318 | compiler passes. They can also test the C variable |
2319 | @code{current_function_uses_only_leaf_regs} which is nonzero for leaf | |
2320 | functions which only use leaf registers. | |
9ac617d4 EB |
2321 | @code{current_function_uses_only_leaf_regs} is valid after all passes |
2322 | that modify the instructions have been run and is only useful if | |
2323 | @code{LEAF_REGISTERS} is defined. | |
feca2ed3 JW |
2324 | @c changed this to fix overfull. ALSO: why the "it" at the beginning |
2325 | @c of the next paragraph?! --mew 2feb93 | |
2326 | ||
2327 | @node Stack Registers | |
2328 | @subsection Registers That Form a Stack | |
2329 | ||
2330 | There are special features to handle computers where some of the | |
a2c4f8e0 ZW |
2331 | ``registers'' form a stack. Stack registers are normally written by |
2332 | pushing onto the stack, and are numbered relative to the top of the | |
2333 | stack. | |
feca2ed3 | 2334 | |
a3a15b4d | 2335 | Currently, GCC can only handle one group of stack-like registers, and |
a2c4f8e0 ZW |
2336 | they must be consecutively numbered. Furthermore, the existing |
2337 | support for stack-like registers is specific to the 80387 floating | |
2338 | point coprocessor. If you have a new architecture that uses | |
2339 | stack-like registers, you will need to do substantial work on | |
2340 | @file{reg-stack.c} and write your machine description to cooperate | |
2341 | with it, as well as defining these macros. | |
2342 | ||
2343 | @defmac STACK_REGS | |
feca2ed3 | 2344 | Define this if the machine has any stack-like registers. |
a2c4f8e0 | 2345 | @end defmac |
feca2ed3 | 2346 | |
a2c4f8e0 | 2347 | @defmac FIRST_STACK_REG |
feca2ed3 JW |
2348 | The number of the first stack-like register. This one is the top |
2349 | of the stack. | |
a2c4f8e0 | 2350 | @end defmac |
feca2ed3 | 2351 | |
a2c4f8e0 | 2352 | @defmac LAST_STACK_REG |
feca2ed3 JW |
2353 | The number of the last stack-like register. This one is the bottom of |
2354 | the stack. | |
a2c4f8e0 | 2355 | @end defmac |
feca2ed3 | 2356 | |
feca2ed3 JW |
2357 | @node Register Classes |
2358 | @section Register Classes | |
2359 | @cindex register class definitions | |
2360 | @cindex class definitions, register | |
2361 | ||
2362 | On many machines, the numbered registers are not all equivalent. | |
2363 | For example, certain registers may not be allowed for indexed addressing; | |
2364 | certain registers may not be allowed in some instructions. These machine | |
2365 | restrictions are described to the compiler using @dfn{register classes}. | |
2366 | ||
2367 | You define a number of register classes, giving each one a name and saying | |
2368 | which of the registers belong to it. Then you can specify register classes | |
2369 | that are allowed as operands to particular instruction patterns. | |
2370 | ||
2371 | @findex ALL_REGS | |
2372 | @findex NO_REGS | |
2373 | In general, each register will belong to several classes. In fact, one | |
2374 | class must be named @code{ALL_REGS} and contain all the registers. Another | |
2375 | class must be named @code{NO_REGS} and contain no registers. Often the | |
2376 | union of two classes will be another class; however, this is not required. | |
2377 | ||
2378 | @findex GENERAL_REGS | |
2379 | One of the classes must be named @code{GENERAL_REGS}. There is nothing | |
2380 | terribly special about the name, but the operand constraint letters | |
2381 | @samp{r} and @samp{g} specify this class. If @code{GENERAL_REGS} is | |
2382 | the same as @code{ALL_REGS}, just define it as a macro which expands | |
2383 | to @code{ALL_REGS}. | |
2384 | ||
2385 | Order the classes so that if class @var{x} is contained in class @var{y} | |
2386 | then @var{x} has a lower class number than @var{y}. | |
2387 | ||
2388 | The way classes other than @code{GENERAL_REGS} are specified in operand | |
2389 | constraints is through machine-dependent operand constraint letters. | |
2390 | You can define such letters to correspond to various classes, then use | |
2391 | them in operand constraints. | |
2392 | ||
2393 | You should define a class for the union of two classes whenever some | |
2394 | instruction allows both classes. For example, if an instruction allows | |
2395 | either a floating point (coprocessor) register or a general register for a | |
2396 | certain operand, you should define a class @code{FLOAT_OR_GENERAL_REGS} | |
2397 | which includes both of them. Otherwise you will get suboptimal code. | |
2398 | ||
2399 | You must also specify certain redundant information about the register | |
2400 | classes: for each class, which classes contain it and which ones are | |
2401 | contained in it; for each pair of classes, the largest class contained | |
2402 | in their union. | |
2403 | ||
2404 | When a value occupying several consecutive registers is expected in a | |
2405 | certain class, all the registers used must belong to that class. | |
2406 | Therefore, register classes cannot be used to enforce a requirement for | |
2407 | a register pair to start with an even-numbered register. The way to | |
2408 | specify this requirement is with @code{HARD_REGNO_MODE_OK}. | |
2409 | ||
2410 | Register classes used for input-operands of bitwise-and or shift | |
2411 | instructions have a special requirement: each such class must have, for | |
2412 | each fixed-point machine mode, a subclass whose registers can transfer that | |
2413 | mode to or from memory. For example, on some machines, the operations for | |
2414 | single-byte values (@code{QImode}) are limited to certain registers. When | |
2415 | this is so, each register class that is used in a bitwise-and or shift | |
2416 | instruction must have a subclass consisting of registers from which | |
2417 | single-byte values can be loaded or stored. This is so that | |
2418 | @code{PREFERRED_RELOAD_CLASS} can always have a possible value to return. | |
2419 | ||
a2c4f8e0 | 2420 | @deftp {Data type} {enum reg_class} |
2eac577f JM |
2421 | An enumerated type that must be defined with all the register class names |
2422 | as enumerated values. @code{NO_REGS} must be first. @code{ALL_REGS} | |
2423 | must be the last register class, followed by one more enumerated value, | |
feca2ed3 JW |
2424 | @code{LIM_REG_CLASSES}, which is not a register class but rather |
2425 | tells how many classes there are. | |
2426 | ||
2427 | Each register class has a number, which is the value of casting | |
2428 | the class name to type @code{int}. The number serves as an index | |
2429 | in many of the tables described below. | |
a2c4f8e0 | 2430 | @end deftp |
feca2ed3 | 2431 | |
a2c4f8e0 | 2432 | @defmac N_REG_CLASSES |
feca2ed3 JW |
2433 | The number of distinct register classes, defined as follows: |
2434 | ||
3ab51846 | 2435 | @smallexample |
feca2ed3 | 2436 | #define N_REG_CLASSES (int) LIM_REG_CLASSES |
3ab51846 | 2437 | @end smallexample |
a2c4f8e0 | 2438 | @end defmac |
feca2ed3 | 2439 | |
a2c4f8e0 | 2440 | @defmac REG_CLASS_NAMES |
feca2ed3 JW |
2441 | An initializer containing the names of the register classes as C string |
2442 | constants. These names are used in writing some of the debugging dumps. | |
a2c4f8e0 | 2443 | @end defmac |
feca2ed3 | 2444 | |
a2c4f8e0 | 2445 | @defmac REG_CLASS_CONTENTS |
feca2ed3 JW |
2446 | An initializer containing the contents of the register classes, as integers |
2447 | which are bit masks. The @var{n}th integer specifies the contents of class | |
2448 | @var{n}. The way the integer @var{mask} is interpreted is that | |
2449 | register @var{r} is in the class if @code{@var{mask} & (1 << @var{r})} is 1. | |
2450 | ||
2451 | When the machine has more than 32 registers, an integer does not suffice. | |
2452 | Then the integers are replaced by sub-initializers, braced groupings containing | |
2453 | several integers. Each sub-initializer must be suitable as an initializer | |
2454 | for the type @code{HARD_REG_SET} which is defined in @file{hard-reg-set.h}. | |
7c272079 MP |
2455 | In this situation, the first integer in each sub-initializer corresponds to |
2456 | registers 0 through 31, the second integer to registers 32 through 63, and | |
2457 | so on. | |
a2c4f8e0 | 2458 | @end defmac |
feca2ed3 | 2459 | |
a2c4f8e0 | 2460 | @defmac REGNO_REG_CLASS (@var{regno}) |
feca2ed3 JW |
2461 | A C expression whose value is a register class containing hard register |
2462 | @var{regno}. In general there is more than one such class; choose a class | |
2463 | which is @dfn{minimal}, meaning that no smaller class also contains the | |
2464 | register. | |
a2c4f8e0 | 2465 | @end defmac |
feca2ed3 | 2466 | |
a2c4f8e0 | 2467 | @defmac BASE_REG_CLASS |
feca2ed3 JW |
2468 | A macro whose definition is the name of the class to which a valid |
2469 | base register must belong. A base register is one used in an address | |
2470 | which is the register value plus a displacement. | |
a2c4f8e0 | 2471 | @end defmac |
feca2ed3 | 2472 | |
a2c4f8e0 | 2473 | @defmac MODE_BASE_REG_CLASS (@var{mode}) |
3dcc68a4 | 2474 | This is a variation of the @code{BASE_REG_CLASS} macro which allows |
c0478a66 | 2475 | the selection of a base register in a mode dependent manner. If |
3dcc68a4 NC |
2476 | @var{mode} is VOIDmode then it should return the same value as |
2477 | @code{BASE_REG_CLASS}. | |
a2c4f8e0 | 2478 | @end defmac |
3dcc68a4 | 2479 | |
888d2cd6 DJ |
2480 | @defmac MODE_BASE_REG_REG_CLASS (@var{mode}) |
2481 | A C expression whose value is the register class to which a valid | |
2482 | base register must belong in order to be used in a base plus index | |
2483 | register address. You should define this macro if base plus index | |
2484 | addresses have different requirements than other base register uses. | |
2485 | @end defmac | |
2486 | ||
c4963a0a BS |
2487 | @defmac MODE_CODE_BASE_REG_CLASS (@var{mode}, @var{outer_code}, @var{index_code}) |
2488 | A C expression whose value is the register class to which a valid | |
2489 | base register must belong. @var{outer_code} and @var{index_code} define the | |
2490 | context in which the base register occurs. @var{outer_code} is the code of | |
2491 | the immediately enclosing expression (@code{MEM} for the top level of an | |
2492 | address, @code{ADDRESS} for something that occurs in an | |
2493 | @code{address_operand}). @var{index_code} is the code of the corresponding | |
2494 | index expression if @var{outer_code} is @code{PLUS}; @code{SCRATCH} otherwise. | |
2495 | @end defmac | |
2496 | ||
a2c4f8e0 | 2497 | @defmac INDEX_REG_CLASS |
feca2ed3 JW |
2498 | A macro whose definition is the name of the class to which a valid |
2499 | index register must belong. An index register is one used in an | |
2500 | address where its value is either multiplied by a scale factor or | |
2501 | added to another register (as well as added to a displacement). | |
a2c4f8e0 | 2502 | @end defmac |
feca2ed3 | 2503 | |
a2c4f8e0 | 2504 | @defmac REGNO_OK_FOR_BASE_P (@var{num}) |
feca2ed3 | 2505 | A C expression which is nonzero if register number @var{num} is |
1c62e8f2 | 2506 | suitable for use as a base register in operand addresses. |
c6c3dba9 PB |
2507 | Like @code{TARGET_LEGITIMATE_ADDRESS_P}, this macro should also |
2508 | define a strict and a non-strict variant. Both variants behave | |
1c62e8f2 PB |
2509 | the same for hard register; for pseudos, the strict variant will |
2510 | pass only those that have been allocated to a valid hard registers, | |
2511 | while the non-strict variant will pass all pseudos. | |
2512 | ||
2513 | @findex REG_OK_STRICT | |
2514 | Compiler source files that want to use the strict variant of this and | |
2515 | other macros define the macro @code{REG_OK_STRICT}. You should use an | |
2516 | @code{#ifdef REG_OK_STRICT} conditional to define the strict variant in | |
2517 | that case and the non-strict variant otherwise. | |
a2c4f8e0 | 2518 | @end defmac |
feca2ed3 | 2519 | |
a2c4f8e0 | 2520 | @defmac REGNO_MODE_OK_FOR_BASE_P (@var{num}, @var{mode}) |
861bb6c1 JL |
2521 | A C expression that is just like @code{REGNO_OK_FOR_BASE_P}, except that |
2522 | that expression may examine the mode of the memory reference in | |
2523 | @var{mode}. You should define this macro if the mode of the memory | |
2524 | reference affects whether a register may be used as a base register. If | |
2525 | you define this macro, the compiler will use it instead of | |
ab873839 RW |
2526 | @code{REGNO_OK_FOR_BASE_P}. The mode may be @code{VOIDmode} for |
2527 | addresses that appear outside a @code{MEM}, i.e., as an | |
2528 | @code{address_operand}. | |
c4963a0a | 2529 | |
1c62e8f2 | 2530 | This macro also has strict and non-strict variants. |
a2c4f8e0 | 2531 | @end defmac |
861bb6c1 | 2532 | |
888d2cd6 DJ |
2533 | @defmac REGNO_MODE_OK_FOR_REG_BASE_P (@var{num}, @var{mode}) |
2534 | A C expression which is nonzero if register number @var{num} is suitable for | |
2535 | use as a base register in base plus index operand addresses, accessing | |
2536 | memory in mode @var{mode}. It may be either a suitable hard register or a | |
2537 | pseudo register that has been allocated such a hard register. You should | |
2538 | define this macro if base plus index addresses have different requirements | |
2539 | than other base register uses. | |
c4963a0a BS |
2540 | |
2541 | Use of this macro is deprecated; please use the more general | |
2542 | @code{REGNO_MODE_CODE_OK_FOR_BASE_P}. | |
1c62e8f2 PB |
2543 | |
2544 | This macro also has strict and non-strict variants. | |
c4963a0a BS |
2545 | @end defmac |
2546 | ||
2547 | @defmac REGNO_MODE_CODE_OK_FOR_BASE_P (@var{num}, @var{mode}, @var{outer_code}, @var{index_code}) | |
ab873839 RW |
2548 | A C expression that is just like @code{REGNO_MODE_OK_FOR_BASE_P}, except |
2549 | that that expression may examine the context in which the register | |
2550 | appears in the memory reference. @var{outer_code} is the code of the | |
2551 | immediately enclosing expression (@code{MEM} if at the top level of the | |
2552 | address, @code{ADDRESS} for something that occurs in an | |
2553 | @code{address_operand}). @var{index_code} is the code of the | |
2554 | corresponding index expression if @var{outer_code} is @code{PLUS}; | |
c4963a0a | 2555 | @code{SCRATCH} otherwise. The mode may be @code{VOIDmode} for addresses |
ab873839 | 2556 | that appear outside a @code{MEM}, i.e., as an @code{address_operand}. |
1c62e8f2 PB |
2557 | |
2558 | This macro also has strict and non-strict variants. | |
888d2cd6 DJ |
2559 | @end defmac |
2560 | ||
a2c4f8e0 | 2561 | @defmac REGNO_OK_FOR_INDEX_P (@var{num}) |
feca2ed3 JW |
2562 | A C expression which is nonzero if register number @var{num} is |
2563 | suitable for use as an index register in operand addresses. It may be | |
2564 | either a suitable hard register or a pseudo register that has been | |
2565 | allocated such a hard register. | |
2566 | ||
2567 | The difference between an index register and a base register is that | |
2568 | the index register may be scaled. If an address involves the sum of | |
2569 | two registers, neither one of them scaled, then either one may be | |
2570 | labeled the ``base'' and the other the ``index''; but whichever | |
2571 | labeling is used must fit the machine's constraints of which registers | |
2572 | may serve in each capacity. The compiler will try both labelings, | |
2573 | looking for one that is valid, and will reload one or both registers | |
2574 | only if neither labeling works. | |
1c62e8f2 PB |
2575 | |
2576 | This macro also has strict and non-strict variants. | |
a2c4f8e0 | 2577 | @end defmac |
feca2ed3 | 2578 | |
a2c4f8e0 | 2579 | @defmac PREFERRED_RELOAD_CLASS (@var{x}, @var{class}) |
feca2ed3 JW |
2580 | A C expression that places additional restrictions on the register class |
2581 | to use when it is necessary to copy value @var{x} into a register in class | |
2582 | @var{class}. The value is a register class; perhaps @var{class}, or perhaps | |
2583 | another, smaller class. On many machines, the following definition is | |
2584 | safe: | |
2585 | ||
3ab51846 | 2586 | @smallexample |
feca2ed3 | 2587 | #define PREFERRED_RELOAD_CLASS(X,CLASS) CLASS |
3ab51846 | 2588 | @end smallexample |
feca2ed3 JW |
2589 | |
2590 | Sometimes returning a more restrictive class makes better code. For | |
2591 | example, on the 68000, when @var{x} is an integer constant that is in range | |
2592 | for a @samp{moveq} instruction, the value of this macro is always | |
2593 | @code{DATA_REGS} as long as @var{class} includes the data registers. | |
2594 | Requiring a data register guarantees that a @samp{moveq} will be used. | |
2595 | ||
222a2f1a GK |
2596 | One case where @code{PREFERRED_RELOAD_CLASS} must not return |
2597 | @var{class} is if @var{x} is a legitimate constant which cannot be | |
2598 | loaded into some register class. By returning @code{NO_REGS} you can | |
2599 | force @var{x} into a memory location. For example, rs6000 can load | |
2600 | immediate values into general-purpose registers, but does not have an | |
2601 | instruction for loading an immediate value into a floating-point | |
2602 | register, so @code{PREFERRED_RELOAD_CLASS} returns @code{NO_REGS} when | |
2603 | @var{x} is a floating-point constant. If the constant can't be loaded | |
2604 | into any kind of register, code generation will be better if | |
2605 | @code{LEGITIMATE_CONSTANT_P} makes the constant illegitimate instead | |
2606 | of using @code{PREFERRED_RELOAD_CLASS}. | |
b5c82fa1 PB |
2607 | |
2608 | If an insn has pseudos in it after register allocation, reload will go | |
2609 | through the alternatives and call repeatedly @code{PREFERRED_RELOAD_CLASS} | |
2610 | to find the best one. Returning @code{NO_REGS}, in this case, makes | |
2611 | reload add a @code{!} in front of the constraint: the x86 back-end uses | |
2612 | this feature to discourage usage of 387 registers when math is done in | |
2613 | the SSE registers (and vice versa). | |
a2c4f8e0 | 2614 | @end defmac |
feca2ed3 | 2615 | |
a2c4f8e0 | 2616 | @defmac PREFERRED_OUTPUT_RELOAD_CLASS (@var{x}, @var{class}) |
feca2ed3 JW |
2617 | Like @code{PREFERRED_RELOAD_CLASS}, but for output reloads instead of |
2618 | input reloads. If you don't define this macro, the default is to use | |
2619 | @var{class}, unchanged. | |
b5c82fa1 PB |
2620 | |
2621 | You can also use @code{PREFERRED_OUTPUT_RELOAD_CLASS} to discourage | |
2622 | reload from using some alternatives, like @code{PREFERRED_RELOAD_CLASS}. | |
a2c4f8e0 | 2623 | @end defmac |
feca2ed3 | 2624 | |
a2c4f8e0 | 2625 | @defmac LIMIT_RELOAD_CLASS (@var{mode}, @var{class}) |
feca2ed3 JW |
2626 | A C expression that places additional restrictions on the register class |
2627 | to use when it is necessary to be able to hold a value of mode | |
2628 | @var{mode} in a reload register for which class @var{class} would | |
2629 | ordinarily be used. | |
2630 | ||
2631 | Unlike @code{PREFERRED_RELOAD_CLASS}, this macro should be used when | |
2632 | there are certain modes that simply can't go in certain reload classes. | |
2633 | ||
2634 | The value is a register class; perhaps @var{class}, or perhaps another, | |
2635 | smaller class. | |
2636 | ||
2637 | Don't define this macro unless the target machine has limitations which | |
2638 | require the macro to do something nontrivial. | |
a2c4f8e0 | 2639 | @end defmac |
feca2ed3 | 2640 | |
17f6dbbf | 2641 | @deftypefn {Target Hook} {enum reg_class} TARGET_SECONDARY_RELOAD (bool @var{in_p}, rtx @var{x}, enum reg_class @var{reload_class}, enum machine_mode @var{reload_mode}, secondary_reload_info *@var{sri}) |
feca2ed3 JW |
2642 | Many machines have some registers that cannot be copied directly to or |
2643 | from memory or even from other types of registers. An example is the | |
2644 | @samp{MQ} register, which on most machines, can only be copied to or | |
8a99f6f9 R |
2645 | from general registers, but not memory. Below, we shall be using the |
2646 | term 'intermediate register' when a move operation cannot be performed | |
2647 | directly, but has to be done by copying the source into the intermediate | |
2648 | register first, and then copying the intermediate register to the | |
2649 | destination. An intermediate register always has the same mode as | |
2650 | source and destination. Since it holds the actual value being copied, | |
2651 | reload might apply optimizations to re-use an intermediate register | |
2652 | and eliding the copy from the source when it can determine that the | |
2653 | intermediate register still holds the required value. | |
2654 | ||
2655 | Another kind of secondary reload is required on some machines which | |
2656 | allow copying all registers to and from memory, but require a scratch | |
2657 | register for stores to some memory locations (e.g., those with symbolic | |
2658 | address on the RT, and those with certain symbolic address on the SPARC | |
2659 | when compiling PIC)@. Scratch registers need not have the same mode | |
e4ae5e77 | 2660 | as the value being copied, and usually hold a different value than |
8a99f6f9 R |
2661 | that being copied. Special patterns in the md file are needed to |
2662 | describe how the copy is performed with the help of the scratch register; | |
2663 | these patterns also describe the number, register class(es) and mode(s) | |
2664 | of the scratch register(s). | |
2665 | ||
2666 | In some cases, both an intermediate and a scratch register are required. | |
2667 | ||
2668 | For input reloads, this target hook is called with nonzero @var{in_p}, | |
9bdf23b2 | 2669 | and @var{x} is an rtx that needs to be copied to a register of class |
8a99f6f9 | 2670 | @var{reload_class} in @var{reload_mode}. For output reloads, this target |
9bdf23b2 | 2671 | hook is called with zero @var{in_p}, and a register of class @var{reload_class} |
8a99f6f9 R |
2672 | needs to be copied to rtx @var{x} in @var{reload_mode}. |
2673 | ||
2674 | If copying a register of @var{reload_class} from/to @var{x} requires | |
2675 | an intermediate register, the hook @code{secondary_reload} should | |
2676 | return the register class required for this intermediate register. | |
2677 | If no intermediate register is required, it should return NO_REGS. | |
2678 | If more than one intermediate register is required, describe the one | |
2679 | that is closest in the copy chain to the reload register. | |
2680 | ||
2681 | If scratch registers are needed, you also have to describe how to | |
2682 | perform the copy from/to the reload register to/from this | |
2683 | closest intermediate register. Or if no intermediate register is | |
2684 | required, but still a scratch register is needed, describe the | |
2685 | copy from/to the reload register to/from the reload operand @var{x}. | |
2686 | ||
2687 | You do this by setting @code{sri->icode} to the instruction code of a pattern | |
2688 | in the md file which performs the move. Operands 0 and 1 are the output | |
2689 | and input of this copy, respectively. Operands from operand 2 onward are | |
2690 | for scratch operands. These scratch operands must have a mode, and a | |
2691 | single-register-class | |
2692 | @c [later: or memory] | |
2693 | output constraint. | |
2694 | ||
2695 | When an intermediate register is used, the @code{secondary_reload} | |
2696 | hook will be called again to determine how to copy the intermediate | |
2697 | register to/from the reload operand @var{x}, so your hook must also | |
2698 | have code to handle the register class of the intermediate operand. | |
2699 | ||
2700 | @c [For later: maybe we'll allow multi-alternative reload patterns - | |
2701 | @c the port maintainer could name a mov<mode> pattern that has clobbers - | |
2702 | @c and match the constraints of input and output to determine the required | |
2703 | @c alternative. A restriction would be that constraints used to match | |
2704 | @c against reloads registers would have to be written as register class | |
2705 | @c constraints, or we need a new target macro / hook that tells us if an | |
2706 | @c arbitrary constraint can match an unknown register of a given class. | |
2707 | @c Such a macro / hook would also be useful in other places.] | |
2708 | ||
2709 | ||
2710 | @var{x} might be a pseudo-register or a @code{subreg} of a | |
2711 | pseudo-register, which could either be in a hard register or in memory. | |
2712 | Use @code{true_regnum} to find out; it will return @minus{}1 if the pseudo is | |
2713 | in memory and the hard register number if it is in a register. | |
2714 | ||
2715 | Scratch operands in memory (constraint @code{"=m"} / @code{"=&m"}) are | |
2716 | currently not supported. For the time being, you will have to continue | |
2717 | to use @code{SECONDARY_MEMORY_NEEDED} for that purpose. | |
2718 | ||
2719 | @code{copy_cost} also uses this target hook to find out how values are | |
2720 | copied. If you want it to include some extra cost for the need to allocate | |
2721 | (a) scratch register(s), set @code{sri->extra_cost} to the additional cost. | |
2722 | Or if two dependent moves are supposed to have a lower cost than the sum | |
2723 | of the individual moves due to expected fortuitous scheduling and/or special | |
2724 | forwarding logic, you can set @code{sri->extra_cost} to a negative amount. | |
2725 | @end deftypefn | |
2726 | ||
2727 | @defmac SECONDARY_RELOAD_CLASS (@var{class}, @var{mode}, @var{x}) | |
2728 | @defmacx SECONDARY_INPUT_RELOAD_CLASS (@var{class}, @var{mode}, @var{x}) | |
2729 | @defmacx SECONDARY_OUTPUT_RELOAD_CLASS (@var{class}, @var{mode}, @var{x}) | |
083cad55 | 2730 | These macros are obsolete, new ports should use the target hook |
8a99f6f9 R |
2731 | @code{TARGET_SECONDARY_RELOAD} instead. |
2732 | ||
2733 | These are obsolete macros, replaced by the @code{TARGET_SECONDARY_RELOAD} | |
2734 | target hook. Older ports still define these macros to indicate to the | |
2735 | reload phase that it may | |
feca2ed3 JW |
2736 | need to allocate at least one register for a reload in addition to the |
2737 | register to contain the data. Specifically, if copying @var{x} to a | |
2738 | register @var{class} in @var{mode} requires an intermediate register, | |
8a99f6f9 | 2739 | you were supposed to define @code{SECONDARY_INPUT_RELOAD_CLASS} to return the |
feca2ed3 JW |
2740 | largest register class all of whose registers can be used as |
2741 | intermediate registers or scratch registers. | |
2742 | ||
2743 | If copying a register @var{class} in @var{mode} to @var{x} requires an | |
2744 | intermediate or scratch register, @code{SECONDARY_OUTPUT_RELOAD_CLASS} | |
8a99f6f9 R |
2745 | was supposed to be defined be defined to return the largest register |
2746 | class required. If the | |
2747 | requirements for input and output reloads were the same, the macro | |
2748 | @code{SECONDARY_RELOAD_CLASS} should have been used instead of defining both | |
feca2ed3 JW |
2749 | macros identically. |
2750 | ||
2751 | The values returned by these macros are often @code{GENERAL_REGS}. | |
2752 | Return @code{NO_REGS} if no spare register is needed; i.e., if @var{x} | |
2753 | can be directly copied to or from a register of @var{class} in | |
2754 | @var{mode} without requiring a scratch register. Do not define this | |
2755 | macro if it would always return @code{NO_REGS}. | |
2756 | ||
2757 | If a scratch register is required (either with or without an | |
8a99f6f9 | 2758 | intermediate register), you were supposed to define patterns for |
feca2ed3 | 2759 | @samp{reload_in@var{m}} or @samp{reload_out@var{m}}, as required |
8a99f6f9 | 2760 | (@pxref{Standard Names}. These patterns, which were normally |
feca2ed3 JW |
2761 | implemented with a @code{define_expand}, should be similar to the |
2762 | @samp{mov@var{m}} patterns, except that operand 2 is the scratch | |
2763 | register. | |
2764 | ||
8a99f6f9 R |
2765 | These patterns need constraints for the reload register and scratch |
2766 | register that | |
feca2ed3 JW |
2767 | contain a single register class. If the original reload register (whose |
2768 | class is @var{class}) can meet the constraint given in the pattern, the | |
2769 | value returned by these macros is used for the class of the scratch | |
2770 | register. Otherwise, two additional reload registers are required. | |
2771 | Their classes are obtained from the constraints in the insn pattern. | |
2772 | ||
2773 | @var{x} might be a pseudo-register or a @code{subreg} of a | |
2774 | pseudo-register, which could either be in a hard register or in memory. | |
630d3d5a | 2775 | Use @code{true_regnum} to find out; it will return @minus{}1 if the pseudo is |
feca2ed3 JW |
2776 | in memory and the hard register number if it is in a register. |
2777 | ||
2778 | These macros should not be used in the case where a particular class of | |
2779 | registers can only be copied to memory and not to another class of | |
2780 | registers. In that case, secondary reload registers are not needed and | |
2781 | would not be helpful. Instead, a stack location must be used to perform | |
a8154559 | 2782 | the copy and the @code{mov@var{m}} pattern should use memory as an |
feca2ed3 JW |
2783 | intermediate storage. This case often occurs between floating-point and |
2784 | general registers. | |
a2c4f8e0 | 2785 | @end defmac |
feca2ed3 | 2786 | |
a2c4f8e0 | 2787 | @defmac SECONDARY_MEMORY_NEEDED (@var{class1}, @var{class2}, @var{m}) |
feca2ed3 JW |
2788 | Certain machines have the property that some registers cannot be copied |
2789 | to some other registers without using memory. Define this macro on | |
df2a54e9 | 2790 | those machines to be a C expression that is nonzero if objects of mode |
feca2ed3 JW |
2791 | @var{m} in registers of @var{class1} can only be copied to registers of |
2792 | class @var{class2} by storing a register of @var{class1} into memory | |
2793 | and loading that memory location into a register of @var{class2}. | |
2794 | ||
2795 | Do not define this macro if its value would always be zero. | |
a2c4f8e0 | 2796 | @end defmac |
feca2ed3 | 2797 | |
a2c4f8e0 | 2798 | @defmac SECONDARY_MEMORY_NEEDED_RTX (@var{mode}) |
feca2ed3 JW |
2799 | Normally when @code{SECONDARY_MEMORY_NEEDED} is defined, the compiler |
2800 | allocates a stack slot for a memory location needed for register copies. | |
2801 | If this macro is defined, the compiler instead uses the memory location | |
2802 | defined by this macro. | |
2803 | ||
2804 | Do not define this macro if you do not define | |
2805 | @code{SECONDARY_MEMORY_NEEDED}. | |
a2c4f8e0 | 2806 | @end defmac |
feca2ed3 | 2807 | |
a2c4f8e0 | 2808 | @defmac SECONDARY_MEMORY_NEEDED_MODE (@var{mode}) |
feca2ed3 JW |
2809 | When the compiler needs a secondary memory location to copy between two |
2810 | registers of mode @var{mode}, it normally allocates sufficient memory to | |
2811 | hold a quantity of @code{BITS_PER_WORD} bits and performs the store and | |
2812 | load operations in a mode that many bits wide and whose class is the | |
2813 | same as that of @var{mode}. | |
2814 | ||
2815 | This is right thing to do on most machines because it ensures that all | |
2816 | bits of the register are copied and prevents accesses to the registers | |
2817 | in a narrower mode, which some machines prohibit for floating-point | |
2818 | registers. | |
2819 | ||
2820 | However, this default behavior is not correct on some machines, such as | |
2821 | the DEC Alpha, that store short integers in floating-point registers | |
2822 | differently than in integer registers. On those machines, the default | |
2823 | widening will not work correctly and you must define this macro to | |
2824 | suppress that widening in some cases. See the file @file{alpha.h} for | |
2825 | details. | |
2826 | ||
2827 | Do not define this macro if you do not define | |
2828 | @code{SECONDARY_MEMORY_NEEDED} or if widening @var{mode} to a mode that | |
2829 | is @code{BITS_PER_WORD} bits wide is correct for your machine. | |
a2c4f8e0 | 2830 | @end defmac |
feca2ed3 | 2831 | |
a2c4f8e0 | 2832 | @defmac SMALL_REGISTER_CLASSES |
faa9eb19 BS |
2833 | On some machines, it is risky to let hard registers live across arbitrary |
2834 | insns. Typically, these machines have instructions that require values | |
2835 | to be in specific registers (like an accumulator), and reload will fail | |
2836 | if the required hard register is used for another purpose across such an | |
2837 | insn. | |
feca2ed3 | 2838 | |
df2a54e9 JM |
2839 | Define @code{SMALL_REGISTER_CLASSES} to be an expression with a nonzero |
2840 | value on these machines. When this macro has a nonzero value, the | |
faa9eb19 | 2841 | compiler will try to minimize the lifetime of hard registers. |
feca2ed3 | 2842 | |
df2a54e9 | 2843 | It is always safe to define this macro with a nonzero value, but if you |
861bb6c1 JL |
2844 | unnecessarily define it, you will reduce the amount of optimizations |
2845 | that can be performed in some cases. If you do not define this macro | |
df2a54e9 | 2846 | with a nonzero value when it is required, the compiler will run out of |
861bb6c1 JL |
2847 | spill registers and print a fatal error message. For most machines, you |
2848 | should not define this macro at all. | |
a2c4f8e0 | 2849 | @end defmac |
feca2ed3 | 2850 | |
a2c4f8e0 | 2851 | @defmac CLASS_LIKELY_SPILLED_P (@var{class}) |
feca2ed3 JW |
2852 | A C expression whose value is nonzero if pseudos that have been assigned |
2853 | to registers of class @var{class} would likely be spilled because | |
2854 | registers of @var{class} are needed for spill registers. | |
2855 | ||
2856 | The default value of this macro returns 1 if @var{class} has exactly one | |
2857 | register and zero otherwise. On most machines, this default should be | |
40687a9e | 2858 | used. Only define this macro to some other expression if pseudos |
feca2ed3 JW |
2859 | allocated by @file{local-alloc.c} end up in memory because their hard |
2860 | registers were needed for spill registers. If this macro returns nonzero | |
2861 | for those classes, those pseudos will only be allocated by | |
2862 | @file{global.c}, which knows how to reallocate the pseudo to another | |
2863 | register. If there would not be another register available for | |
2864 | reallocation, you should not change the definition of this macro since | |
2865 | the only effect of such a definition would be to slow down register | |
2866 | allocation. | |
a2c4f8e0 | 2867 | @end defmac |
feca2ed3 | 2868 | |
a2c4f8e0 | 2869 | @defmac CLASS_MAX_NREGS (@var{class}, @var{mode}) |
feca2ed3 JW |
2870 | A C expression for the maximum number of consecutive registers |
2871 | of class @var{class} needed to hold a value of mode @var{mode}. | |
2872 | ||
2873 | This is closely related to the macro @code{HARD_REGNO_NREGS}. In fact, | |
2874 | the value of the macro @code{CLASS_MAX_NREGS (@var{class}, @var{mode})} | |
2875 | should be the maximum value of @code{HARD_REGNO_NREGS (@var{regno}, | |
2876 | @var{mode})} for all @var{regno} values in the class @var{class}. | |
2877 | ||
2878 | This macro helps control the handling of multiple-word values | |
2879 | in the reload pass. | |
a2c4f8e0 | 2880 | @end defmac |
feca2ed3 | 2881 | |
a2c4f8e0 | 2882 | @defmac CANNOT_CHANGE_MODE_CLASS (@var{from}, @var{to}, @var{class}) |
b0c42aed JH |
2883 | If defined, a C expression that returns nonzero for a @var{class} for which |
2884 | a change from mode @var{from} to mode @var{to} is invalid. | |
feca2ed3 JW |
2885 | |
2886 | For the example, loading 32-bit integer or floating-point objects into | |
57694e40 | 2887 | floating-point registers on the Alpha extends them to 64 bits. |
feca2ed3 | 2888 | Therefore loading a 64-bit object and then storing it as a 32-bit object |
57694e40 | 2889 | does not store the low-order 32 bits, as would be the case for a normal |
cff9f8d5 AH |
2890 | register. Therefore, @file{alpha.h} defines @code{CANNOT_CHANGE_MODE_CLASS} |
2891 | as below: | |
02188693 | 2892 | |
3ab51846 | 2893 | @smallexample |
b0c42aed JH |
2894 | #define CANNOT_CHANGE_MODE_CLASS(FROM, TO, CLASS) \ |
2895 | (GET_MODE_SIZE (FROM) != GET_MODE_SIZE (TO) \ | |
2896 | ? reg_classes_intersect_p (FLOAT_REGS, (CLASS)) : 0) | |
3ab51846 | 2897 | @end smallexample |
a2c4f8e0 | 2898 | @end defmac |
feca2ed3 | 2899 | |
76e68dca RS |
2900 | @deftypefn {Target Hook} {const enum reg_class *} TARGET_IRA_COVER_CLASSES () |
2901 | Return an array of cover classes for the Integrated Register Allocator | |
058e97ec VM |
2902 | (@acronym{IRA}). Cover classes are a set of non-intersecting register |
2903 | classes covering all hard registers used for register allocation | |
af9253a1 | 2904 | purposes. If a move between two registers in the same cover class is |
4cda38d5 | 2905 | possible, it should be cheaper than a load or store of the registers. |
76e68dca RS |
2906 | The array is terminated by a @code{LIM_REG_CLASSES} element. |
2907 | ||
2908 | This hook is called once at compiler startup, after the command-line | |
2909 | options have been processed. It is then re-examined by every call to | |
2910 | @code{target_reinit}. | |
058e97ec | 2911 | |
76e68dca RS |
2912 | The default implementation returns @code{IRA_COVER_CLASSES}, if defined, |
2913 | otherwise there is no default implementation. You must define either this | |
2914 | macro or @code{IRA_COVER_CLASSES} in order to use the integrated register | |
7db7ed3c VM |
2915 | allocator with Chaitin-Briggs coloring. If the macro is not defined, |
2916 | the only available coloring algorithm is Chow's priority coloring. | |
76e68dca RS |
2917 | @end deftypefn |
2918 | ||
2919 | @defmac IRA_COVER_CLASSES | |
2920 | See the documentation for @code{TARGET_IRA_COVER_CLASSES}. | |
058e97ec VM |
2921 | @end defmac |
2922 | ||
f38840db ZW |
2923 | @node Old Constraints |
2924 | @section Obsolete Macros for Defining Constraints | |
2925 | @cindex defining constraints, obsolete method | |
2926 | @cindex constraints, defining, obsolete method | |
2927 | ||
2928 | Machine-specific constraints can be defined with these macros instead | |
2929 | of the machine description constructs described in @ref{Define | |
2930 | Constraints}. This mechanism is obsolete. New ports should not use | |
2931 | it; old ports should convert to the new mechanism. | |
2932 | ||
2933 | @defmac CONSTRAINT_LEN (@var{char}, @var{str}) | |
2934 | For the constraint at the start of @var{str}, which starts with the letter | |
2935 | @var{c}, return the length. This allows you to have register class / | |
2936 | constant / extra constraints that are longer than a single letter; | |
2937 | you don't need to define this macro if you can do with single-letter | |
2938 | constraints only. The definition of this macro should use | |
2939 | DEFAULT_CONSTRAINT_LEN for all the characters that you don't want | |
2940 | to handle specially. | |
2941 | There are some sanity checks in genoutput.c that check the constraint lengths | |
2942 | for the md file, so you can also use this macro to help you while you are | |
2943 | transitioning from a byzantine single-letter-constraint scheme: when you | |
2944 | return a negative length for a constraint you want to re-use, genoutput | |
2945 | will complain about every instance where it is used in the md file. | |
2946 | @end defmac | |
2947 | ||
2948 | @defmac REG_CLASS_FROM_LETTER (@var{char}) | |
2949 | A C expression which defines the machine-dependent operand constraint | |
2950 | letters for register classes. If @var{char} is such a letter, the | |
2951 | value should be the register class corresponding to it. Otherwise, | |
2952 | the value should be @code{NO_REGS}. The register letter @samp{r}, | |
2953 | corresponding to class @code{GENERAL_REGS}, will not be passed | |
2954 | to this macro; you do not need to handle it. | |
2955 | @end defmac | |
2956 | ||
2957 | @defmac REG_CLASS_FROM_CONSTRAINT (@var{char}, @var{str}) | |
2958 | Like @code{REG_CLASS_FROM_LETTER}, but you also get the constraint string | |
2959 | passed in @var{str}, so that you can use suffixes to distinguish between | |
2960 | different variants. | |
2961 | @end defmac | |
feca2ed3 | 2962 | |
a2c4f8e0 | 2963 | @defmac CONST_OK_FOR_LETTER_P (@var{value}, @var{c}) |
e119b68c MM |
2964 | A C expression that defines the machine-dependent operand constraint |
2965 | letters (@samp{I}, @samp{J}, @samp{K}, @dots{} @samp{P}) that specify | |
2966 | particular ranges of integer values. If @var{c} is one of those | |
2967 | letters, the expression should check that @var{value}, an integer, is in | |
2968 | the appropriate range and return 1 if so, 0 otherwise. If @var{c} is | |
2969 | not one of those letters, the value should be 0 regardless of | |
2970 | @var{value}. | |
a2c4f8e0 | 2971 | @end defmac |
feca2ed3 | 2972 | |
a2c4f8e0 | 2973 | @defmac CONST_OK_FOR_CONSTRAINT_P (@var{value}, @var{c}, @var{str}) |
97488870 R |
2974 | Like @code{CONST_OK_FOR_LETTER_P}, but you also get the constraint |
2975 | string passed in @var{str}, so that you can use suffixes to distinguish | |
2976 | between different variants. | |
a2c4f8e0 | 2977 | @end defmac |
97488870 | 2978 | |
a2c4f8e0 | 2979 | @defmac CONST_DOUBLE_OK_FOR_LETTER_P (@var{value}, @var{c}) |
feca2ed3 | 2980 | A C expression that defines the machine-dependent operand constraint |
e119b68c MM |
2981 | letters that specify particular ranges of @code{const_double} values |
2982 | (@samp{G} or @samp{H}). | |
feca2ed3 JW |
2983 | |
2984 | If @var{c} is one of those letters, the expression should check that | |
2985 | @var{value}, an RTX of code @code{const_double}, is in the appropriate | |
2986 | range and return 1 if so, 0 otherwise. If @var{c} is not one of those | |
2987 | letters, the value should be 0 regardless of @var{value}. | |
2988 | ||
2989 | @code{const_double} is used for all floating-point constants and for | |
2990 | @code{DImode} fixed-point constants. A given letter can accept either | |
2991 | or both kinds of values. It can use @code{GET_MODE} to distinguish | |
2992 | between these kinds. | |
a2c4f8e0 | 2993 | @end defmac |
feca2ed3 | 2994 | |
a2c4f8e0 | 2995 | @defmac CONST_DOUBLE_OK_FOR_CONSTRAINT_P (@var{value}, @var{c}, @var{str}) |
97488870 R |
2996 | Like @code{CONST_DOUBLE_OK_FOR_LETTER_P}, but you also get the constraint |
2997 | string passed in @var{str}, so that you can use suffixes to distinguish | |
2998 | between different variants. | |
a2c4f8e0 | 2999 | @end defmac |
97488870 | 3000 | |
a2c4f8e0 | 3001 | @defmac EXTRA_CONSTRAINT (@var{value}, @var{c}) |
feca2ed3 | 3002 | A C expression that defines the optional machine-dependent constraint |
c2cba7a9 RH |
3003 | letters that can be used to segregate specific types of operands, usually |
3004 | memory references, for the target machine. Any letter that is not | |
97488870 R |
3005 | elsewhere defined and not matched by @code{REG_CLASS_FROM_LETTER} / |
3006 | @code{REG_CLASS_FROM_CONSTRAINT} | |
c2cba7a9 RH |
3007 | may be used. Normally this macro will not be defined. |
3008 | ||
3009 | If it is required for a particular target machine, it should return 1 | |
3010 | if @var{value} corresponds to the operand type represented by the | |
3011 | constraint letter @var{c}. If @var{c} is not defined as an extra | |
e119b68c | 3012 | constraint, the value returned should be 0 regardless of @var{value}. |
feca2ed3 | 3013 | |
c2cba7a9 RH |
3014 | For example, on the ROMP, load instructions cannot have their output |
3015 | in r0 if the memory reference contains a symbolic address. Constraint | |
3016 | letter @samp{Q} is defined as representing a memory address that does | |
feca2ed3 JW |
3017 | @emph{not} contain a symbolic address. An alternative is specified with |
3018 | a @samp{Q} constraint on the input and @samp{r} on the output. The next | |
3019 | alternative specifies @samp{m} on the input and a register class that | |
3020 | does not include r0 on the output. | |
a2c4f8e0 | 3021 | @end defmac |
ccfc6cc8 | 3022 | |
a2c4f8e0 | 3023 | @defmac EXTRA_CONSTRAINT_STR (@var{value}, @var{c}, @var{str}) |
97488870 R |
3024 | Like @code{EXTRA_CONSTRAINT}, but you also get the constraint string passed |
3025 | in @var{str}, so that you can use suffixes to distinguish between different | |
3026 | variants. | |
a2c4f8e0 | 3027 | @end defmac |
97488870 | 3028 | |
a2c4f8e0 | 3029 | @defmac EXTRA_MEMORY_CONSTRAINT (@var{c}, @var{str}) |
ccfc6cc8 UW |
3030 | A C expression that defines the optional machine-dependent constraint |
3031 | letters, amongst those accepted by @code{EXTRA_CONSTRAINT}, that should | |
3032 | be treated like memory constraints by the reload pass. | |
3033 | ||
73774972 | 3034 | It should return 1 if the operand type represented by the constraint |
97488870 | 3035 | at the start of @var{str}, the first letter of which is the letter @var{c}, |
6ccde948 | 3036 | comprises a subset of all memory references including |
73774972 EC |
3037 | all those whose address is simply a base register. This allows the reload |
3038 | pass to reload an operand, if it does not directly correspond to the operand | |
ccfc6cc8 UW |
3039 | type of @var{c}, by copying its address into a base register. |
3040 | ||
3041 | For example, on the S/390, some instructions do not accept arbitrary | |
3042 | memory references, but only those that do not make use of an index | |
3043 | register. The constraint letter @samp{Q} is defined via | |
3044 | @code{EXTRA_CONSTRAINT} as representing a memory address of this type. | |
3045 | If the letter @samp{Q} is marked as @code{EXTRA_MEMORY_CONSTRAINT}, | |
3046 | a @samp{Q} constraint can handle any memory operand, because the | |
3047 | reload pass knows it can be reloaded by copying the memory address | |
3048 | into a base register if required. This is analogous to the way | |
e4ae5e77 | 3049 | an @samp{o} constraint can handle any memory operand. |
a2c4f8e0 | 3050 | @end defmac |
ccfc6cc8 | 3051 | |
a2c4f8e0 | 3052 | @defmac EXTRA_ADDRESS_CONSTRAINT (@var{c}, @var{str}) |
ccfc6cc8 | 3053 | A C expression that defines the optional machine-dependent constraint |
97488870 R |
3054 | letters, amongst those accepted by @code{EXTRA_CONSTRAINT} / |
3055 | @code{EXTRA_CONSTRAINT_STR}, that should | |
ccfc6cc8 UW |
3056 | be treated like address constraints by the reload pass. |
3057 | ||
73774972 | 3058 | It should return 1 if the operand type represented by the constraint |
3a6e2189 | 3059 | at the start of @var{str}, which starts with the letter @var{c}, comprises |
97488870 | 3060 | a subset of all memory addresses including |
73774972 EC |
3061 | all those that consist of just a base register. This allows the reload |
3062 | pass to reload an operand, if it does not directly correspond to the operand | |
97488870 | 3063 | type of @var{str}, by copying it into a base register. |
ccfc6cc8 UW |
3064 | |
3065 | Any constraint marked as @code{EXTRA_ADDRESS_CONSTRAINT} can only | |
73774972 | 3066 | be used with the @code{address_operand} predicate. It is treated |
ccfc6cc8 | 3067 | analogously to the @samp{p} constraint. |
a2c4f8e0 | 3068 | @end defmac |
feca2ed3 JW |
3069 | |
3070 | @node Stack and Calling | |
3071 | @section Stack Layout and Calling Conventions | |
3072 | @cindex calling conventions | |
3073 | ||
3074 | @c prevent bad page break with this line | |
3075 | This describes the stack layout and calling conventions. | |
3076 | ||
3077 | @menu | |
3078 | * Frame Layout:: | |
7c16328b | 3079 | * Exception Handling:: |
861bb6c1 | 3080 | * Stack Checking:: |
feca2ed3 JW |
3081 | * Frame Registers:: |
3082 | * Elimination:: | |
3083 | * Stack Arguments:: | |
3084 | * Register Arguments:: | |
3085 | * Scalar Return:: | |
3086 | * Aggregate Return:: | |
3087 | * Caller Saves:: | |
3088 | * Function Entry:: | |
3089 | * Profiling:: | |
91d231cb | 3090 | * Tail Calls:: |
7d69de61 | 3091 | * Stack Smashing Protection:: |
feca2ed3 JW |
3092 | @end menu |
3093 | ||
3094 | @node Frame Layout | |
3095 | @subsection Basic Stack Layout | |
3096 | @cindex stack frame layout | |
3097 | @cindex frame layout | |
3098 | ||
3099 | @c prevent bad page break with this line | |
3100 | Here is the basic stack layout. | |
3101 | ||
a2c4f8e0 | 3102 | @defmac STACK_GROWS_DOWNWARD |
feca2ed3 JW |
3103 | Define this macro if pushing a word onto the stack moves the stack |
3104 | pointer to a smaller address. | |
3105 | ||
d78aa55c | 3106 | When we say, ``define this macro if @dots{}'', it means that the |
feca2ed3 JW |
3107 | compiler checks this macro only with @code{#ifdef} so the precise |
3108 | definition used does not matter. | |
a2c4f8e0 | 3109 | @end defmac |
feca2ed3 | 3110 | |
a2c4f8e0 | 3111 | @defmac STACK_PUSH_CODE |
918a6124 GK |
3112 | This macro defines the operation used when something is pushed |
3113 | on the stack. In RTL, a push operation will be | |
04a5176a | 3114 | @code{(set (mem (STACK_PUSH_CODE (reg sp))) @dots{})} |
918a6124 GK |
3115 | |
3116 | The choices are @code{PRE_DEC}, @code{POST_DEC}, @code{PRE_INC}, | |
3117 | and @code{POST_INC}. Which of these is correct depends on | |
3118 | the stack direction and on whether the stack pointer points | |
3119 | to the last item on the stack or whether it points to the | |
3120 | space for the next item on the stack. | |
3121 | ||
3122 | The default is @code{PRE_DEC} when @code{STACK_GROWS_DOWNWARD} is | |
3123 | defined, which is almost always right, and @code{PRE_INC} otherwise, | |
3124 | which is often wrong. | |
a2c4f8e0 | 3125 | @end defmac |
918a6124 | 3126 | |
a2c4f8e0 | 3127 | @defmac FRAME_GROWS_DOWNWARD |
a4d05547 | 3128 | Define this macro to nonzero value if the addresses of local variable slots |
f62c8a5c | 3129 | are at negative offsets from the frame pointer. |
a2c4f8e0 | 3130 | @end defmac |
feca2ed3 | 3131 | |
a2c4f8e0 | 3132 | @defmac ARGS_GROW_DOWNWARD |
feca2ed3 JW |
3133 | Define this macro if successive arguments to a function occupy decreasing |
3134 | addresses on the stack. | |
a2c4f8e0 | 3135 | @end defmac |
feca2ed3 | 3136 | |
a2c4f8e0 | 3137 | @defmac STARTING_FRAME_OFFSET |
feca2ed3 JW |
3138 | Offset from the frame pointer to the first local variable slot to be allocated. |
3139 | ||
3140 | If @code{FRAME_GROWS_DOWNWARD}, find the next slot's offset by | |
3141 | subtracting the first slot's length from @code{STARTING_FRAME_OFFSET}. | |
3142 | Otherwise, it is found by adding the length of the first slot to the | |
3143 | value @code{STARTING_FRAME_OFFSET}. | |
3144 | @c i'm not sure if the above is still correct.. had to change it to get | |
3145 | @c rid of an overfull. --mew 2feb93 | |
a2c4f8e0 | 3146 | @end defmac |
feca2ed3 | 3147 | |
a2c4f8e0 | 3148 | @defmac STACK_ALIGNMENT_NEEDED |
95f3f59e | 3149 | Define to zero to disable final alignment of the stack during reload. |
0b4be7de | 3150 | The nonzero default for this macro is suitable for most ports. |
95f3f59e | 3151 | |
0b4be7de | 3152 | On ports where @code{STARTING_FRAME_OFFSET} is nonzero or where there |
95f3f59e JDA |
3153 | is a register save block following the local block that doesn't require |
3154 | alignment to @code{STACK_BOUNDARY}, it may be beneficial to disable | |
3155 | stack alignment and do it in the backend. | |
a2c4f8e0 | 3156 | @end defmac |
95f3f59e | 3157 | |
a2c4f8e0 | 3158 | @defmac STACK_POINTER_OFFSET |
feca2ed3 JW |
3159 | Offset from the stack pointer register to the first location at which |
3160 | outgoing arguments are placed. If not specified, the default value of | |
3161 | zero is used. This is the proper value for most machines. | |
3162 | ||
3163 | If @code{ARGS_GROW_DOWNWARD}, this is the offset to the location above | |
3164 | the first location at which outgoing arguments are placed. | |
a2c4f8e0 | 3165 | @end defmac |
feca2ed3 | 3166 | |
a2c4f8e0 | 3167 | @defmac FIRST_PARM_OFFSET (@var{fundecl}) |
feca2ed3 JW |
3168 | Offset from the argument pointer register to the first argument's |
3169 | address. On some machines it may depend on the data type of the | |
3170 | function. | |
3171 | ||
3172 | If @code{ARGS_GROW_DOWNWARD}, this is the offset to the location above | |
3173 | the first argument's address. | |
a2c4f8e0 | 3174 | @end defmac |
feca2ed3 | 3175 | |
a2c4f8e0 | 3176 | @defmac STACK_DYNAMIC_OFFSET (@var{fundecl}) |
feca2ed3 JW |
3177 | Offset from the stack pointer register to an item dynamically allocated |
3178 | on the stack, e.g., by @code{alloca}. | |
3179 | ||
3180 | The default value for this macro is @code{STACK_POINTER_OFFSET} plus the | |
3181 | length of the outgoing arguments. The default is correct for most | |
3182 | machines. See @file{function.c} for details. | |
a2c4f8e0 | 3183 | @end defmac |
feca2ed3 | 3184 | |
c6d01079 AK |
3185 | @defmac INITIAL_FRAME_ADDRESS_RTX |
3186 | A C expression whose value is RTL representing the address of the initial | |
083cad55 | 3187 | stack frame. This address is passed to @code{RETURN_ADDR_RTX} and |
c8f27794 JW |
3188 | @code{DYNAMIC_CHAIN_ADDRESS}. If you don't define this macro, a reasonable |
3189 | default value will be used. Define this macro in order to make frame pointer | |
083cad55 | 3190 | elimination work in the presence of @code{__builtin_frame_address (count)} and |
c8f27794 | 3191 | @code{__builtin_return_address (count)} for @code{count} not equal to zero. |
c6d01079 AK |
3192 | @end defmac |
3193 | ||
a2c4f8e0 | 3194 | @defmac DYNAMIC_CHAIN_ADDRESS (@var{frameaddr}) |
feca2ed3 JW |
3195 | A C expression whose value is RTL representing the address in a stack |
3196 | frame where the pointer to the caller's frame is stored. Assume that | |
3197 | @var{frameaddr} is an RTL expression for the address of the stack frame | |
3198 | itself. | |
3199 | ||
3200 | If you don't define this macro, the default is to return the value | |
3201 | of @var{frameaddr}---that is, the stack frame address is also the | |
3202 | address of the stack word that points to the previous frame. | |
a2c4f8e0 | 3203 | @end defmac |
feca2ed3 | 3204 | |
a2c4f8e0 | 3205 | @defmac SETUP_FRAME_ADDRESSES |
feca2ed3 JW |
3206 | If defined, a C expression that produces the machine-specific code to |
3207 | setup the stack so that arbitrary frames can be accessed. For example, | |
981f6289 | 3208 | on the SPARC, we must flush all of the register windows to the stack |
0bc02db4 MS |
3209 | before we can access arbitrary stack frames. You will seldom need to |
3210 | define this macro. | |
a2c4f8e0 | 3211 | @end defmac |
0bc02db4 | 3212 | |
d6da68b9 KH |
3213 | @deftypefn {Target Hook} bool TARGET_BUILTIN_SETJMP_FRAME_VALUE () |
3214 | This target hook should return an rtx that is used to store | |
0bc02db4 MS |
3215 | the address of the current frame into the built in @code{setjmp} buffer. |
3216 | The default value, @code{virtual_stack_vars_rtx}, is correct for most | |
d6da68b9 | 3217 | machines. One reason you may need to define this target hook is if |
0bc02db4 | 3218 | @code{hard_frame_pointer_rtx} is the appropriate value on your machine. |
d6da68b9 | 3219 | @end deftypefn |
feca2ed3 | 3220 | |
224869d9 EB |
3221 | @defmac FRAME_ADDR_RTX (@var{frameaddr}) |
3222 | A C expression whose value is RTL representing the value of the frame | |
3223 | address for the current frame. @var{frameaddr} is the frame pointer | |
3224 | of the current frame. This is used for __builtin_frame_address. | |
3225 | You need only define this macro if the frame address is not the same | |
3226 | as the frame pointer. Most machines do not need to define it. | |
3227 | @end defmac | |
3228 | ||
a2c4f8e0 | 3229 | @defmac RETURN_ADDR_RTX (@var{count}, @var{frameaddr}) |
feca2ed3 | 3230 | A C expression whose value is RTL representing the value of the return |
861bb6c1 JL |
3231 | address for the frame @var{count} steps up from the current frame, after |
3232 | the prologue. @var{frameaddr} is the frame pointer of the @var{count} | |
3233 | frame, or the frame pointer of the @var{count} @minus{} 1 frame if | |
feca2ed3 JW |
3234 | @code{RETURN_ADDR_IN_PREVIOUS_FRAME} is defined. |
3235 | ||
e9a25f70 | 3236 | The value of the expression must always be the correct address when |
4830ba1f | 3237 | @var{count} is zero, but may be @code{NULL_RTX} if there is no way to |
e9a25f70 | 3238 | determine the return address of other frames. |
a2c4f8e0 | 3239 | @end defmac |
e9a25f70 | 3240 | |
a2c4f8e0 | 3241 | @defmac RETURN_ADDR_IN_PREVIOUS_FRAME |
feca2ed3 JW |
3242 | Define this if the return address of a particular stack frame is accessed |
3243 | from the frame pointer of the previous stack frame. | |
a2c4f8e0 | 3244 | @end defmac |
861bb6c1 | 3245 | |
a2c4f8e0 | 3246 | @defmac INCOMING_RETURN_ADDR_RTX |
861bb6c1 JL |
3247 | A C expression whose value is RTL representing the location of the |
3248 | incoming return address at the beginning of any function, before the | |
3249 | prologue. This RTL is either a @code{REG}, indicating that the return | |
3250 | value is saved in @samp{REG}, or a @code{MEM} representing a location in | |
3251 | the stack. | |
3252 | ||
3253 | You only need to define this macro if you want to support call frame | |
3254 | debugging information like that provided by DWARF 2. | |
3255 | ||
2c849145 | 3256 | If this RTL is a @code{REG}, you should also define |
aee96fe9 | 3257 | @code{DWARF_FRAME_RETURN_COLUMN} to @code{DWARF_FRAME_REGNUM (REGNO)}. |
a2c4f8e0 | 3258 | @end defmac |
2c849145 | 3259 | |
ed80cd68 | 3260 | @defmac DWARF_ALT_FRAME_RETURN_COLUMN |
73774972 | 3261 | A C expression whose value is an integer giving a DWARF 2 column |
5cd0f915 RS |
3262 | number that may be used as an alternative return column. The column |
3263 | must not correspond to any gcc hard register (that is, it must not | |
3264 | be in the range of @code{DWARF_FRAME_REGNUM}). | |
3265 | ||
3266 | This macro can be useful if @code{DWARF_FRAME_RETURN_COLUMN} is set to a | |
3267 | general register, but an alternative column needs to be used for signal | |
3268 | frames. Some targets have also used different frame return columns | |
3269 | over time. | |
ed80cd68 RH |
3270 | @end defmac |
3271 | ||
282efe1c RH |
3272 | @defmac DWARF_ZERO_REG |
3273 | A C expression whose value is an integer giving a DWARF 2 register | |
3274 | number that is considered to always have the value zero. This should | |
3275 | only be defined if the target has an architected zero register, and | |
3276 | someone decided it was a good idea to use that register number to | |
3277 | terminate the stack backtrace. New ports should avoid this. | |
3278 | @end defmac | |
3279 | ||
e54c7471 EB |
3280 | @deftypefn {Target Hook} void TARGET_DWARF_HANDLE_FRAME_UNSPEC (const char *@var{label}, rtx @var{pattern}, int @var{index}) |
3281 | This target hook allows the backend to emit frame-related insns that | |
3282 | contain UNSPECs or UNSPEC_VOLATILEs. The DWARF 2 call frame debugging | |
3283 | info engine will invoke it on insns of the form | |
3284 | @smallexample | |
923158be | 3285 | (set (reg) (unspec [@dots{}] UNSPEC_INDEX)) |
e54c7471 EB |
3286 | @end smallexample |
3287 | and | |
3288 | @smallexample | |
923158be | 3289 | (set (reg) (unspec_volatile [@dots{}] UNSPECV_INDEX)). |
e54c7471 EB |
3290 | @end smallexample |
3291 | to let the backend emit the call frame instructions. @var{label} is | |
3292 | the CFI label attached to the insn, @var{pattern} is the pattern of | |
3293 | the insn and @var{index} is @code{UNSPEC_INDEX} or @code{UNSPECV_INDEX}. | |
3294 | @end deftypefn | |
3295 | ||
a2c4f8e0 | 3296 | @defmac INCOMING_FRAME_SP_OFFSET |
861bb6c1 JL |
3297 | A C expression whose value is an integer giving the offset, in bytes, |
3298 | from the value of the stack pointer register to the top of the stack | |
3299 | frame at the beginning of any function, before the prologue. The top of | |
3300 | the frame is defined to be the value of the stack pointer in the | |
3301 | previous frame, just before the call instruction. | |
3302 | ||
71038426 RH |
3303 | You only need to define this macro if you want to support call frame |
3304 | debugging information like that provided by DWARF 2. | |
a2c4f8e0 | 3305 | @end defmac |
71038426 | 3306 | |
a2c4f8e0 | 3307 | @defmac ARG_POINTER_CFA_OFFSET (@var{fundecl}) |
71038426 RH |
3308 | A C expression whose value is an integer giving the offset, in bytes, |
3309 | from the argument pointer to the canonical frame address (cfa). The | |
02f52e19 | 3310 | final value should coincide with that calculated by |
71038426 RH |
3311 | @code{INCOMING_FRAME_SP_OFFSET}. Which is unfortunately not usable |
3312 | during virtual register instantiation. | |
3313 | ||
2c849145 JM |
3314 | The default value for this macro is @code{FIRST_PARM_OFFSET (fundecl)}, |
3315 | which is correct for most machines; in general, the arguments are found | |
208e52d9 JM |
3316 | immediately before the stack frame. Note that this is not the case on |
3317 | some targets that save registers into the caller's frame, such as SPARC | |
3318 | and rs6000, and so such targets need to define this macro. | |
2c849145 | 3319 | |
208e52d9 | 3320 | You only need to define this macro if the default is incorrect, and you |
2c849145 JM |
3321 | want to support call frame debugging information like that provided by |
3322 | DWARF 2. | |
a2c4f8e0 | 3323 | @end defmac |
512b62fb | 3324 | |
f6672e8e RH |
3325 | @defmac FRAME_POINTER_CFA_OFFSET (@var{fundecl}) |
3326 | If defined, a C expression whose value is an integer giving the offset | |
3327 | in bytes from the frame pointer to the canonical frame address (cfa). | |
6fc0bb99 | 3328 | The final value should coincide with that calculated by |
f6672e8e RH |
3329 | @code{INCOMING_FRAME_SP_OFFSET}. |
3330 | ||
3331 | Normally the CFA is calculated as an offset from the argument pointer, | |
083cad55 | 3332 | via @code{ARG_POINTER_CFA_OFFSET}, but if the argument pointer is |
f6672e8e | 3333 | variable due to the ABI, this may not be possible. If this macro is |
6416ae7f | 3334 | defined, it implies that the virtual register instantiation should be |
f6672e8e RH |
3335 | based on the frame pointer instead of the argument pointer. Only one |
3336 | of @code{FRAME_POINTER_CFA_OFFSET} and @code{ARG_POINTER_CFA_OFFSET} | |
3337 | should be defined. | |
3338 | @end defmac | |
3339 | ||
35d177a2 AO |
3340 | @defmac CFA_FRAME_BASE_OFFSET (@var{fundecl}) |
3341 | If defined, a C expression whose value is an integer giving the offset | |
3342 | in bytes from the canonical frame address (cfa) to the frame base used | |
3343 | in DWARF 2 debug information. The default is zero. A different value | |
3344 | may reduce the size of debug information on some ports. | |
3345 | @end defmac | |
3346 | ||
7c16328b RH |
3347 | @node Exception Handling |
3348 | @subsection Exception Handling Support | |
3349 | @cindex exception handling | |
3350 | ||
a2c4f8e0 | 3351 | @defmac EH_RETURN_DATA_REGNO (@var{N}) |
52a11cbf RH |
3352 | A C expression whose value is the @var{N}th register number used for |
3353 | data by exception handlers, or @code{INVALID_REGNUM} if fewer than | |
3354 | @var{N} registers are usable. | |
3355 | ||
3356 | The exception handling library routines communicate with the exception | |
3357 | handlers via a set of agreed upon registers. Ideally these registers | |
3358 | should be call-clobbered; it is possible to use call-saved registers, | |
3359 | but may negatively impact code size. The target must support at least | |
3360 | 2 data registers, but should define 4 if there are enough free registers. | |
3361 | ||
3362 | You must define this macro if you want to support call frame exception | |
3363 | handling like that provided by DWARF 2. | |
a2c4f8e0 | 3364 | @end defmac |
52a11cbf | 3365 | |
a2c4f8e0 | 3366 | @defmac EH_RETURN_STACKADJ_RTX |
52a11cbf RH |
3367 | A C expression whose value is RTL representing a location in which |
3368 | to store a stack adjustment to be applied before function return. | |
3369 | This is used to unwind the stack to an exception handler's call frame. | |
3370 | It will be assigned zero on code paths that return normally. | |
3371 | ||
02f52e19 | 3372 | Typically this is a call-clobbered hard register that is otherwise |
52a11cbf RH |
3373 | untouched by the epilogue, but could also be a stack slot. |
3374 | ||
34dc173c | 3375 | Do not define this macro if the stack pointer is saved and restored |
73774972 EC |
3376 | by the regular prolog and epilog code in the call frame itself; in |
3377 | this case, the exception handling library routines will update the | |
3378 | stack location to be restored in place. Otherwise, you must define | |
3379 | this macro if you want to support call frame exception handling like | |
34dc173c | 3380 | that provided by DWARF 2. |
a2c4f8e0 | 3381 | @end defmac |
52a11cbf | 3382 | |
a2c4f8e0 | 3383 | @defmac EH_RETURN_HANDLER_RTX |
52a11cbf | 3384 | A C expression whose value is RTL representing a location in which |
02f52e19 | 3385 | to store the address of an exception handler to which we should |
52a11cbf RH |
3386 | return. It will not be assigned on code paths that return normally. |
3387 | ||
3388 | Typically this is the location in the call frame at which the normal | |
02f52e19 AJ |
3389 | return address is stored. For targets that return by popping an |
3390 | address off the stack, this might be a memory address just below | |
52a11cbf | 3391 | the @emph{target} call frame rather than inside the current call |
73774972 EC |
3392 | frame. If defined, @code{EH_RETURN_STACKADJ_RTX} will have already |
3393 | been assigned, so it may be used to calculate the location of the | |
34dc173c | 3394 | target call frame. |
52a11cbf RH |
3395 | |
3396 | Some targets have more complex requirements than storing to an | |
3397 | address calculable during initial code generation. In that case | |
3398 | the @code{eh_return} instruction pattern should be used instead. | |
3399 | ||
3400 | If you want to support call frame exception handling, you must | |
3401 | define either this macro or the @code{eh_return} instruction pattern. | |
a2c4f8e0 | 3402 | @end defmac |
52a11cbf | 3403 | |
1e60c057 R |
3404 | @defmac RETURN_ADDR_OFFSET |
3405 | If defined, an integer-valued C expression for which rtl will be generated | |
3406 | to add it to the exception handler address before it is searched in the | |
3407 | exception handling tables, and to subtract it again from the address before | |
3408 | using it to return to the exception handler. | |
3409 | @end defmac | |
3410 | ||
a2c4f8e0 | 3411 | @defmac ASM_PREFERRED_EH_DATA_FORMAT (@var{code}, @var{global}) |
2a1ee410 RH |
3412 | This macro chooses the encoding of pointers embedded in the exception |
3413 | handling sections. If at all possible, this should be defined such | |
3414 | that the exception handling section will not require dynamic relocations, | |
3415 | and so may be read-only. | |
3416 | ||
aee96fe9 JM |
3417 | @var{code} is 0 for data, 1 for code labels, 2 for function pointers. |
3418 | @var{global} is true if the symbol may be affected by dynamic relocations. | |
2a1ee410 RH |
3419 | The macro should return a combination of the @code{DW_EH_PE_*} defines |
3420 | as found in @file{dwarf2.h}. | |
3421 | ||
ebb48a4d | 3422 | If this macro is not defined, pointers will not be encoded but |
2a1ee410 | 3423 | represented directly. |
a2c4f8e0 | 3424 | @end defmac |
2a1ee410 | 3425 | |
a2c4f8e0 | 3426 | @defmac ASM_MAYBE_OUTPUT_ENCODED_ADDR_RTX (@var{file}, @var{encoding}, @var{size}, @var{addr}, @var{done}) |
2a1ee410 RH |
3427 | This macro allows the target to emit whatever special magic is required |
3428 | to represent the encoding chosen by @code{ASM_PREFERRED_EH_DATA_FORMAT}. | |
3429 | Generic code takes care of pc-relative and indirect encodings; this must | |
3430 | be defined if the target uses text-relative or data-relative encodings. | |
3431 | ||
aee96fe9 JM |
3432 | This is a C statement that branches to @var{done} if the format was |
3433 | handled. @var{encoding} is the format chosen, @var{size} is the number | |
3434 | of bytes that the format occupies, @var{addr} is the @code{SYMBOL_REF} | |
2a1ee410 | 3435 | to be emitted. |
a2c4f8e0 | 3436 | @end defmac |
2a1ee410 | 3437 | |
8662eb14 AM |
3438 | @defmac MD_UNWIND_SUPPORT |
3439 | A string specifying a file to be #include'd in unwind-dw2.c. The file | |
3440 | so included typically defines @code{MD_FALLBACK_FRAME_STATE_FOR}. | |
3441 | @end defmac | |
3442 | ||
3443 | @defmac MD_FALLBACK_FRAME_STATE_FOR (@var{context}, @var{fs}) | |
44082375 | 3444 | This macro allows the target to add CPU and operating system specific |
7c16328b RH |
3445 | code to the call-frame unwinder for use when there is no unwind data |
3446 | available. The most common reason to implement this macro is to unwind | |
3447 | through signal frames. | |
3448 | ||
614e5a7d BE |
3449 | This macro is called from @code{uw_frame_state_for} in |
3450 | @file{unwind-dw2.c}, @file{unwind-dw2-xtensa.c} and | |
3451 | @file{unwind-ia64.c}. @var{context} is an @code{_Unwind_Context}; | |
7c16328b RH |
3452 | @var{fs} is an @code{_Unwind_FrameState}. Examine @code{context->ra} |
3453 | for the address of the code being executed and @code{context->cfa} for | |
614e5a7d BE |
3454 | the stack pointer value. If the frame can be decoded, the register |
3455 | save addresses should be updated in @var{fs} and the macro should | |
3456 | evaluate to @code{_URC_NO_REASON}. If the frame cannot be decoded, | |
3457 | the macro should evaluate to @code{_URC_END_OF_STACK}. | |
8207b189 FS |
3458 | |
3459 | For proper signal handling in Java this macro is accompanied by | |
3460 | @code{MAKE_THROW_FRAME}, defined in @file{libjava/include/*-signal.h} headers. | |
a2c4f8e0 | 3461 | @end defmac |
861bb6c1 | 3462 | |
3950dcdf JJ |
3463 | @defmac MD_HANDLE_UNWABI (@var{context}, @var{fs}) |
3464 | This macro allows the target to add operating system specific code to the | |
3465 | call-frame unwinder to handle the IA-64 @code{.unwabi} unwinding directive, | |
3466 | usually used for signal or interrupt frames. | |
3467 | ||
3468 | This macro is called from @code{uw_update_context} in @file{unwind-ia64.c}. | |
3469 | @var{context} is an @code{_Unwind_Context}; | |
3470 | @var{fs} is an @code{_Unwind_FrameState}. Examine @code{fs->unwabi} | |
3471 | for the abi and context in the @code{.unwabi} directive. If the | |
3472 | @code{.unwabi} directive can be handled, the register save addresses should | |
3473 | be updated in @var{fs}. | |
3474 | @end defmac | |
3475 | ||
4746cf84 MA |
3476 | @defmac TARGET_USES_WEAK_UNWIND_INFO |
3477 | A C expression that evaluates to true if the target requires unwind | |
3478 | info to be given comdat linkage. Define it to be @code{1} if comdat | |
3479 | linkage is necessary. The default is @code{0}. | |
3480 | @end defmac | |
3481 | ||
861bb6c1 JL |
3482 | @node Stack Checking |
3483 | @subsection Specifying How Stack Checking is Done | |
3484 | ||
b38f3813 EB |
3485 | GCC will check that stack references are within the boundaries of the |
3486 | stack, if the option @option{-fstack-check} is specified, in one of | |
3487 | three ways: | |
861bb6c1 JL |
3488 | |
3489 | @enumerate | |
3490 | @item | |
a3a15b4d | 3491 | If the value of the @code{STACK_CHECK_BUILTIN} macro is nonzero, GCC |
b38f3813 EB |
3492 | will assume that you have arranged for full stack checking to be done |
3493 | at appropriate places in the configuration files. GCC will not do | |
3494 | other special processing. | |
861bb6c1 JL |
3495 | |
3496 | @item | |
b38f3813 EB |
3497 | If @code{STACK_CHECK_BUILTIN} is zero and the value of the |
3498 | @code{STACK_CHECK_STATIC_BUILTIN} macro is nonzero, GCC will assume | |
3499 | that you have arranged for static stack checking (checking of the | |
3500 | static stack frame of functions) to be done at appropriate places | |
3501 | in the configuration files. GCC will only emit code to do dynamic | |
3502 | stack checking (checking on dynamic stack allocations) using the third | |
3503 | approach below. | |
861bb6c1 JL |
3504 | |
3505 | @item | |
a3a15b4d | 3506 | If neither of the above are true, GCC will generate code to periodically |
861bb6c1 JL |
3507 | ``probe'' the stack pointer using the values of the macros defined below. |
3508 | @end enumerate | |
3509 | ||
b38f3813 EB |
3510 | If neither STACK_CHECK_BUILTIN nor STACK_CHECK_STATIC_BUILTIN is defined, |
3511 | GCC will change its allocation strategy for large objects if the option | |
3512 | @option{-fstack-check} is specified: they will always be allocated | |
3513 | dynamically if their size exceeds @code{STACK_CHECK_MAX_VAR_SIZE} bytes. | |
861bb6c1 | 3514 | |
a2c4f8e0 | 3515 | @defmac STACK_CHECK_BUILTIN |
861bb6c1 | 3516 | A nonzero value if stack checking is done by the configuration files in a |
02f52e19 | 3517 | machine-dependent manner. You should define this macro if stack checking |
b38f3813 EB |
3518 | is require by the ABI of your machine or if you would like to do stack |
3519 | checking in some more efficient way than the generic approach. The default | |
3520 | value of this macro is zero. | |
3521 | @end defmac | |
3522 | ||
3523 | @defmac STACK_CHECK_STATIC_BUILTIN | |
3524 | A nonzero value if static stack checking is done by the configuration files | |
3525 | in a machine-dependent manner. You should define this macro if you would | |
3526 | like to do static stack checking in some more efficient way than the generic | |
3527 | approach. The default value of this macro is zero. | |
a2c4f8e0 | 3528 | @end defmac |
861bb6c1 | 3529 | |
a2c4f8e0 | 3530 | @defmac STACK_CHECK_PROBE_INTERVAL |
a3a15b4d | 3531 | An integer representing the interval at which GCC must generate stack |
861bb6c1 JL |
3532 | probe instructions. You will normally define this macro to be no larger |
3533 | than the size of the ``guard pages'' at the end of a stack area. The | |
3534 | default value of 4096 is suitable for most systems. | |
a2c4f8e0 | 3535 | @end defmac |
861bb6c1 | 3536 | |
a2c4f8e0 | 3537 | @defmac STACK_CHECK_PROBE_LOAD |
b38f3813 | 3538 | An integer which is nonzero if GCC should perform the stack probe |
a3a15b4d | 3539 | as a load instruction and zero if GCC should use a store instruction. |
861bb6c1 | 3540 | The default is zero, which is the most efficient choice on most systems. |
a2c4f8e0 | 3541 | @end defmac |
861bb6c1 | 3542 | |
a2c4f8e0 | 3543 | @defmac STACK_CHECK_PROTECT |
861bb6c1 JL |
3544 | The number of bytes of stack needed to recover from a stack overflow, |
3545 | for languages where such a recovery is supported. The default value of | |
3546 | 75 words should be adequate for most machines. | |
a2c4f8e0 | 3547 | @end defmac |
861bb6c1 | 3548 | |
b38f3813 EB |
3549 | The following macros are relevant only if neither STACK_CHECK_BUILTIN |
3550 | nor STACK_CHECK_STATIC_BUILTIN is defined; you can omit them altogether | |
3551 | in the opposite case. | |
3552 | ||
a2c4f8e0 | 3553 | @defmac STACK_CHECK_MAX_FRAME_SIZE |
a3a15b4d | 3554 | The maximum size of a stack frame, in bytes. GCC will generate probe |
861bb6c1 JL |
3555 | instructions in non-leaf functions to ensure at least this many bytes of |
3556 | stack are available. If a stack frame is larger than this size, stack | |
a3a15b4d JL |
3557 | checking will not be reliable and GCC will issue a warning. The |
3558 | default is chosen so that GCC only generates one instruction on most | |
861bb6c1 | 3559 | systems. You should normally not change the default value of this macro. |
a2c4f8e0 | 3560 | @end defmac |
861bb6c1 | 3561 | |
a2c4f8e0 | 3562 | @defmac STACK_CHECK_FIXED_FRAME_SIZE |
a3a15b4d | 3563 | GCC uses this value to generate the above warning message. It |
861bb6c1 JL |
3564 | represents the amount of fixed frame used by a function, not including |
3565 | space for any callee-saved registers, temporaries and user variables. | |
3566 | You need only specify an upper bound for this amount and will normally | |
3567 | use the default of four words. | |
a2c4f8e0 | 3568 | @end defmac |
861bb6c1 | 3569 | |
a2c4f8e0 | 3570 | @defmac STACK_CHECK_MAX_VAR_SIZE |
a3a15b4d | 3571 | The maximum size, in bytes, of an object that GCC will place in the |
861bb6c1 | 3572 | fixed area of the stack frame when the user specifies |
630d3d5a | 3573 | @option{-fstack-check}. |
a3a15b4d | 3574 | GCC computed the default from the values of the above macros and you will |
861bb6c1 | 3575 | normally not need to override that default. |
a2c4f8e0 | 3576 | @end defmac |
feca2ed3 JW |
3577 | |
3578 | @need 2000 | |
3579 | @node Frame Registers | |
3580 | @subsection Registers That Address the Stack Frame | |
3581 | ||
3582 | @c prevent bad page break with this line | |
3583 | This discusses registers that address the stack frame. | |
3584 | ||
a2c4f8e0 | 3585 | @defmac STACK_POINTER_REGNUM |
feca2ed3 JW |
3586 | The register number of the stack pointer register, which must also be a |
3587 | fixed register according to @code{FIXED_REGISTERS}. On most machines, | |
3588 | the hardware determines which register this is. | |
a2c4f8e0 | 3589 | @end defmac |
feca2ed3 | 3590 | |
a2c4f8e0 | 3591 | @defmac FRAME_POINTER_REGNUM |
feca2ed3 JW |
3592 | The register number of the frame pointer register, which is used to |
3593 | access automatic variables in the stack frame. On some machines, the | |
3594 | hardware determines which register this is. On other machines, you can | |
3595 | choose any register you wish for this purpose. | |
a2c4f8e0 | 3596 | @end defmac |
feca2ed3 | 3597 | |
a2c4f8e0 | 3598 | @defmac HARD_FRAME_POINTER_REGNUM |
feca2ed3 JW |
3599 | On some machines the offset between the frame pointer and starting |
3600 | offset of the automatic variables is not known until after register | |
3601 | allocation has been done (for example, because the saved registers are | |
3602 | between these two locations). On those machines, define | |
3603 | @code{FRAME_POINTER_REGNUM} the number of a special, fixed register to | |
3604 | be used internally until the offset is known, and define | |
556e0f21 | 3605 | @code{HARD_FRAME_POINTER_REGNUM} to be the actual hard register number |
feca2ed3 JW |
3606 | used for the frame pointer. |
3607 | ||
3608 | You should define this macro only in the very rare circumstances when it | |
3609 | is not possible to calculate the offset between the frame pointer and | |
3610 | the automatic variables until after register allocation has been | |
3611 | completed. When this macro is defined, you must also indicate in your | |
3612 | definition of @code{ELIMINABLE_REGS} how to eliminate | |
3613 | @code{FRAME_POINTER_REGNUM} into either @code{HARD_FRAME_POINTER_REGNUM} | |
3614 | or @code{STACK_POINTER_REGNUM}. | |
3615 | ||
3616 | Do not define this macro if it would be the same as | |
3617 | @code{FRAME_POINTER_REGNUM}. | |
a2c4f8e0 | 3618 | @end defmac |
feca2ed3 | 3619 | |
a2c4f8e0 | 3620 | @defmac ARG_POINTER_REGNUM |
feca2ed3 JW |
3621 | The register number of the arg pointer register, which is used to access |
3622 | the function's argument list. On some machines, this is the same as the | |
3623 | frame pointer register. On some machines, the hardware determines which | |
3624 | register this is. On other machines, you can choose any register you | |
3625 | wish for this purpose. If this is not the same register as the frame | |
3626 | pointer register, then you must mark it as a fixed register according to | |
3627 | @code{FIXED_REGISTERS}, or arrange to be able to eliminate it | |
3628 | (@pxref{Elimination}). | |
a2c4f8e0 | 3629 | @end defmac |
feca2ed3 | 3630 | |
a2c4f8e0 | 3631 | @defmac RETURN_ADDRESS_POINTER_REGNUM |
feca2ed3 JW |
3632 | The register number of the return address pointer register, which is used to |
3633 | access the current function's return address from the stack. On some | |
3634 | machines, the return address is not at a fixed offset from the frame | |
3635 | pointer or stack pointer or argument pointer. This register can be defined | |
3636 | to point to the return address on the stack, and then be converted by | |
3637 | @code{ELIMINABLE_REGS} into either the frame pointer or stack pointer. | |
3638 | ||
3639 | Do not define this macro unless there is no other way to get the return | |
3640 | address from the stack. | |
a2c4f8e0 | 3641 | @end defmac |
feca2ed3 | 3642 | |
a2c4f8e0 ZW |
3643 | @defmac STATIC_CHAIN_REGNUM |
3644 | @defmacx STATIC_CHAIN_INCOMING_REGNUM | |
feca2ed3 JW |
3645 | Register numbers used for passing a function's static chain pointer. If |
3646 | register windows are used, the register number as seen by the called | |
3647 | function is @code{STATIC_CHAIN_INCOMING_REGNUM}, while the register | |
3648 | number as seen by the calling function is @code{STATIC_CHAIN_REGNUM}. If | |
3649 | these registers are the same, @code{STATIC_CHAIN_INCOMING_REGNUM} need | |
bd819a4a | 3650 | not be defined. |
feca2ed3 JW |
3651 | |
3652 | The static chain register need not be a fixed register. | |
3653 | ||
3654 | If the static chain is passed in memory, these macros should not be | |
3655 | defined; instead, the next two macros should be defined. | |
a2c4f8e0 | 3656 | @end defmac |
feca2ed3 | 3657 | |
a2c4f8e0 ZW |
3658 | @defmac STATIC_CHAIN |
3659 | @defmacx STATIC_CHAIN_INCOMING | |
feca2ed3 JW |
3660 | If the static chain is passed in memory, these macros provide rtx giving |
3661 | @code{mem} expressions that denote where they are stored. | |
3662 | @code{STATIC_CHAIN} and @code{STATIC_CHAIN_INCOMING} give the locations | |
3663 | as seen by the calling and called functions, respectively. Often the former | |
3664 | will be at an offset from the stack pointer and the latter at an offset from | |
bd819a4a | 3665 | the frame pointer. |
feca2ed3 JW |
3666 | |
3667 | @findex stack_pointer_rtx | |
3668 | @findex frame_pointer_rtx | |
3669 | @findex arg_pointer_rtx | |
3670 | The variables @code{stack_pointer_rtx}, @code{frame_pointer_rtx}, and | |
3671 | @code{arg_pointer_rtx} will have been initialized prior to the use of these | |
3672 | macros and should be used to refer to those items. | |
3673 | ||
3674 | If the static chain is passed in a register, the two previous macros should | |
3675 | be defined instead. | |
a2c4f8e0 | 3676 | @end defmac |
919543ab | 3677 | |
a2c4f8e0 | 3678 | @defmac DWARF_FRAME_REGISTERS |
919543ab AH |
3679 | This macro specifies the maximum number of hard registers that can be |
3680 | saved in a call frame. This is used to size data structures used in | |
3681 | DWARF2 exception handling. | |
3682 | ||
3683 | Prior to GCC 3.0, this macro was needed in order to establish a stable | |
3684 | exception handling ABI in the face of adding new hard registers for ISA | |
3685 | extensions. In GCC 3.0 and later, the EH ABI is insulated from changes | |
3686 | in the number of hard registers. Nevertheless, this macro can still be | |
3687 | used to reduce the runtime memory requirements of the exception handling | |
3688 | routines, which can be substantial if the ISA contains a lot of | |
3689 | registers that are not call-saved. | |
3690 | ||
3691 | If this macro is not defined, it defaults to | |
3692 | @code{FIRST_PSEUDO_REGISTER}. | |
a2c4f8e0 | 3693 | @end defmac |
919543ab | 3694 | |
a2c4f8e0 | 3695 | @defmac PRE_GCC3_DWARF_FRAME_REGISTERS |
919543ab AH |
3696 | |
3697 | This macro is similar to @code{DWARF_FRAME_REGISTERS}, but is provided | |
3698 | for backward compatibility in pre GCC 3.0 compiled code. | |
3699 | ||
3700 | If this macro is not defined, it defaults to | |
3701 | @code{DWARF_FRAME_REGISTERS}. | |
a2c4f8e0 | 3702 | @end defmac |
919543ab | 3703 | |
a2c4f8e0 | 3704 | @defmac DWARF_REG_TO_UNWIND_COLUMN (@var{regno}) |
41f3a930 AH |
3705 | |
3706 | Define this macro if the target's representation for dwarf registers | |
3707 | is different than the internal representation for unwind column. | |
61aeb06f | 3708 | Given a dwarf register, this macro should return the internal unwind |
41f3a930 AH |
3709 | column number to use instead. |
3710 | ||
73774972 | 3711 | See the PowerPC's SPE target for an example. |
a2c4f8e0 | 3712 | @end defmac |
feca2ed3 | 3713 | |
34c80057 AM |
3714 | @defmac DWARF_FRAME_REGNUM (@var{regno}) |
3715 | ||
3716 | Define this macro if the target's representation for dwarf registers | |
3717 | used in .eh_frame or .debug_frame is different from that used in other | |
2dd76960 | 3718 | debug info sections. Given a GCC hard register number, this macro |
34c80057 AM |
3719 | should return the .eh_frame register number. The default is |
3720 | @code{DBX_REGISTER_NUMBER (@var{regno})}. | |
3721 | ||
3722 | @end defmac | |
3723 | ||
3724 | @defmac DWARF2_FRAME_REG_OUT (@var{regno}, @var{for_eh}) | |
3725 | ||
3726 | Define this macro to map register numbers held in the call frame info | |
2dd76960 | 3727 | that GCC has collected using @code{DWARF_FRAME_REGNUM} to those that |
34c80057 | 3728 | should be output in .debug_frame (@code{@var{for_eh}} is zero) and |
f676971a | 3729 | .eh_frame (@code{@var{for_eh}} is nonzero). The default is to |
34c80057 AM |
3730 | return @code{@var{regno}}. |
3731 | ||
3732 | @end defmac | |
3733 | ||
feca2ed3 JW |
3734 | @node Elimination |
3735 | @subsection Eliminating Frame Pointer and Arg Pointer | |
3736 | ||
3737 | @c prevent bad page break with this line | |
3738 | This is about eliminating the frame pointer and arg pointer. | |
3739 | ||
a2c4f8e0 | 3740 | @defmac FRAME_POINTER_REQUIRED |
aea88c05 | 3741 | A C expression which is @code{true} if a function must have and use a frame |
feca2ed3 | 3742 | pointer. This expression is evaluated in the reload pass. If its value is |
aea88c05 | 3743 | @code{true} the function will have a frame pointer. |
feca2ed3 JW |
3744 | |
3745 | The expression can in principle examine the current function and decide | |
aea88c05 AS |
3746 | according to the facts, but on most machines the constant @code{false} or the |
3747 | constant @code{true} suffices. Use @code{false} when the machine allows code | |
3748 | to be generated with no frame pointer, and doing so saves some time or space. | |
3749 | Use @code{true} when there is no possible advantage to avoiding a frame | |
3750 | pointer. | |
feca2ed3 JW |
3751 | |
3752 | In certain cases, the compiler does not know how to produce valid code | |
3753 | without a frame pointer. The compiler recognizes those cases and | |
3754 | automatically gives the function a frame pointer regardless of what | |
3755 | @code{FRAME_POINTER_REQUIRED} says. You don't need to worry about | |
bd819a4a | 3756 | them. |
feca2ed3 JW |
3757 | |
3758 | In a function that does not require a frame pointer, the frame pointer | |
3759 | register can be allocated for ordinary usage, unless you mark it as a | |
3760 | fixed register. See @code{FIXED_REGISTERS} for more information. | |
aea88c05 AS |
3761 | |
3762 | Default value is @code{false}. | |
a2c4f8e0 | 3763 | @end defmac |
feca2ed3 | 3764 | |
feca2ed3 | 3765 | @findex get_frame_size |
a2c4f8e0 | 3766 | @defmac INITIAL_FRAME_POINTER_OFFSET (@var{depth-var}) |
feca2ed3 JW |
3767 | A C statement to store in the variable @var{depth-var} the difference |
3768 | between the frame pointer and the stack pointer values immediately after | |
3769 | the function prologue. The value would be computed from information | |
3770 | such as the result of @code{get_frame_size ()} and the tables of | |
3771 | registers @code{regs_ever_live} and @code{call_used_regs}. | |
3772 | ||
3773 | If @code{ELIMINABLE_REGS} is defined, this macro will be not be used and | |
3774 | need not be defined. Otherwise, it must be defined even if | |
3775 | @code{FRAME_POINTER_REQUIRED} is defined to always be true; in that | |
3776 | case, you may set @var{depth-var} to anything. | |
a2c4f8e0 | 3777 | @end defmac |
feca2ed3 | 3778 | |
a2c4f8e0 | 3779 | @defmac ELIMINABLE_REGS |
feca2ed3 JW |
3780 | If defined, this macro specifies a table of register pairs used to |
3781 | eliminate unneeded registers that point into the stack frame. If it is not | |
3782 | defined, the only elimination attempted by the compiler is to replace | |
3783 | references to the frame pointer with references to the stack pointer. | |
3784 | ||
3785 | The definition of this macro is a list of structure initializations, each | |
3786 | of which specifies an original and replacement register. | |
3787 | ||
3788 | On some machines, the position of the argument pointer is not known until | |
3789 | the compilation is completed. In such a case, a separate hard register | |
3790 | must be used for the argument pointer. This register can be eliminated by | |
3791 | replacing it with either the frame pointer or the argument pointer, | |
3792 | depending on whether or not the frame pointer has been eliminated. | |
3793 | ||
3794 | In this case, you might specify: | |
3ab51846 | 3795 | @smallexample |
feca2ed3 JW |
3796 | #define ELIMINABLE_REGS \ |
3797 | @{@{ARG_POINTER_REGNUM, STACK_POINTER_REGNUM@}, \ | |
3798 | @{ARG_POINTER_REGNUM, FRAME_POINTER_REGNUM@}, \ | |
3799 | @{FRAME_POINTER_REGNUM, STACK_POINTER_REGNUM@}@} | |
3ab51846 | 3800 | @end smallexample |
feca2ed3 JW |
3801 | |
3802 | Note that the elimination of the argument pointer with the stack pointer is | |
3803 | specified first since that is the preferred elimination. | |
a2c4f8e0 | 3804 | @end defmac |
feca2ed3 | 3805 | |
a2c4f8e0 | 3806 | @defmac CAN_ELIMINATE (@var{from-reg}, @var{to-reg}) |
df2a54e9 | 3807 | A C expression that returns nonzero if the compiler is allowed to try |
feca2ed3 JW |
3808 | to replace register number @var{from-reg} with register number |
3809 | @var{to-reg}. This macro need only be defined if @code{ELIMINABLE_REGS} | |
3810 | is defined, and will usually be the constant 1, since most of the cases | |
3811 | preventing register elimination are things that the compiler already | |
3812 | knows about. | |
a2c4f8e0 | 3813 | @end defmac |
feca2ed3 | 3814 | |
a2c4f8e0 | 3815 | @defmac INITIAL_ELIMINATION_OFFSET (@var{from-reg}, @var{to-reg}, @var{offset-var}) |
feca2ed3 JW |
3816 | This macro is similar to @code{INITIAL_FRAME_POINTER_OFFSET}. It |
3817 | specifies the initial difference between the specified pair of | |
3818 | registers. This macro must be defined if @code{ELIMINABLE_REGS} is | |
3819 | defined. | |
a2c4f8e0 | 3820 | @end defmac |
feca2ed3 JW |
3821 | |
3822 | @node Stack Arguments | |
3823 | @subsection Passing Function Arguments on the Stack | |
3824 | @cindex arguments on stack | |
3825 | @cindex stack arguments | |
3826 | ||
3827 | The macros in this section control how arguments are passed | |
3828 | on the stack. See the following section for other macros that | |
3829 | control passing certain arguments in registers. | |
3830 | ||
61f71b34 DD |
3831 | @deftypefn {Target Hook} bool TARGET_PROMOTE_PROTOTYPES (tree @var{fntype}) |
3832 | This target hook returns @code{true} if an argument declared in a | |
3833 | prototype as an integral type smaller than @code{int} should actually be | |
3834 | passed as an @code{int}. In addition to avoiding errors in certain | |
3835 | cases of mismatch, it also makes for better code on certain machines. | |
3836 | The default is to not promote prototypes. | |
3837 | @end deftypefn | |
feca2ed3 | 3838 | |
a2c4f8e0 | 3839 | @defmac PUSH_ARGS |
767094dd | 3840 | A C expression. If nonzero, push insns will be used to pass |
f73ad30e JH |
3841 | outgoing arguments. |
3842 | If the target machine does not have a push instruction, set it to zero. | |
3843 | That directs GCC to use an alternate strategy: to | |
3844 | allocate the entire argument block and then store the arguments into | |
aee96fe9 | 3845 | it. When @code{PUSH_ARGS} is nonzero, @code{PUSH_ROUNDING} must be defined too. |
a2c4f8e0 | 3846 | @end defmac |
f73ad30e | 3847 | |
9d6bef95 JM |
3848 | @defmac PUSH_ARGS_REVERSED |
3849 | A C expression. If nonzero, function arguments will be evaluated from | |
3850 | last to first, rather than from first to last. If this macro is not | |
3851 | defined, it defaults to @code{PUSH_ARGS} on targets where the stack | |
3852 | and args grow in opposite directions, and 0 otherwise. | |
3853 | @end defmac | |
3854 | ||
a2c4f8e0 | 3855 | @defmac PUSH_ROUNDING (@var{npushed}) |
feca2ed3 JW |
3856 | A C expression that is the number of bytes actually pushed onto the |
3857 | stack when an instruction attempts to push @var{npushed} bytes. | |
feca2ed3 JW |
3858 | |
3859 | On some machines, the definition | |
3860 | ||
3ab51846 | 3861 | @smallexample |
feca2ed3 | 3862 | #define PUSH_ROUNDING(BYTES) (BYTES) |
3ab51846 | 3863 | @end smallexample |
feca2ed3 JW |
3864 | |
3865 | @noindent | |
3866 | will suffice. But on other machines, instructions that appear | |
3867 | to push one byte actually push two bytes in an attempt to maintain | |
3868 | alignment. Then the definition should be | |
3869 | ||
3ab51846 | 3870 | @smallexample |
feca2ed3 | 3871 | #define PUSH_ROUNDING(BYTES) (((BYTES) + 1) & ~1) |
3ab51846 | 3872 | @end smallexample |
a2c4f8e0 | 3873 | @end defmac |
feca2ed3 | 3874 | |
feca2ed3 | 3875 | @findex current_function_outgoing_args_size |
a2c4f8e0 | 3876 | @defmac ACCUMULATE_OUTGOING_ARGS |
767094dd | 3877 | A C expression. If nonzero, the maximum amount of space required for outgoing arguments |
feca2ed3 JW |
3878 | will be computed and placed into the variable |
3879 | @code{current_function_outgoing_args_size}. No space will be pushed | |
3880 | onto the stack for each call; instead, the function prologue should | |
3881 | increase the stack frame size by this amount. | |
3882 | ||
f73ad30e | 3883 | Setting both @code{PUSH_ARGS} and @code{ACCUMULATE_OUTGOING_ARGS} |
feca2ed3 | 3884 | is not proper. |
a2c4f8e0 | 3885 | @end defmac |
feca2ed3 | 3886 | |
a2c4f8e0 | 3887 | @defmac REG_PARM_STACK_SPACE (@var{fndecl}) |
feca2ed3 JW |
3888 | Define this macro if functions should assume that stack space has been |
3889 | allocated for arguments even when their values are passed in | |
3890 | registers. | |
3891 | ||
3892 | The value of this macro is the size, in bytes, of the area reserved for | |
ab87f8c8 | 3893 | arguments passed in registers for the function represented by @var{fndecl}, |
a3a15b4d | 3894 | which can be zero if GCC is calling a library function. |
5d059ed9 KT |
3895 | The argument @var{fndecl} can be the FUNCTION_DECL, or the type itself |
3896 | of the function. | |
feca2ed3 JW |
3897 | |
3898 | This space can be allocated by the caller, or be a part of the | |
3899 | machine-dependent stack frame: @code{OUTGOING_REG_PARM_STACK_SPACE} says | |
3900 | which. | |
a2c4f8e0 | 3901 | @end defmac |
feca2ed3 JW |
3902 | @c above is overfull. not sure what to do. --mew 5feb93 did |
3903 | @c something, not sure if it looks good. --mew 10feb93 | |
3904 | ||
81464b2c KT |
3905 | @defmac OUTGOING_REG_PARM_STACK_SPACE (@var{fntype}) |
3906 | Define this to a nonzero value if it is the responsibility of the | |
3907 | caller to allocate the area reserved for arguments passed in registers | |
3908 | when calling a function of @var{fntype}. @var{fntype} may be NULL | |
3909 | if the function called is a library function. | |
feca2ed3 JW |
3910 | |
3911 | If @code{ACCUMULATE_OUTGOING_ARGS} is defined, this macro controls | |
3912 | whether the space for these arguments counts in the value of | |
3913 | @code{current_function_outgoing_args_size}. | |
a2c4f8e0 | 3914 | @end defmac |
feca2ed3 | 3915 | |
a2c4f8e0 | 3916 | @defmac STACK_PARMS_IN_REG_PARM_AREA |
feca2ed3 JW |
3917 | Define this macro if @code{REG_PARM_STACK_SPACE} is defined, but the |
3918 | stack parameters don't skip the area specified by it. | |
3919 | @c i changed this, makes more sens and it should have taken care of the | |
3920 | @c overfull.. not as specific, tho. --mew 5feb93 | |
3921 | ||
3922 | Normally, when a parameter is not passed in registers, it is placed on the | |
3923 | stack beyond the @code{REG_PARM_STACK_SPACE} area. Defining this macro | |
3924 | suppresses this behavior and causes the parameter to be passed on the | |
3925 | stack in its natural location. | |
a2c4f8e0 | 3926 | @end defmac |
feca2ed3 | 3927 | |
a2c4f8e0 | 3928 | @defmac RETURN_POPS_ARGS (@var{fundecl}, @var{funtype}, @var{stack-size}) |
feca2ed3 JW |
3929 | A C expression that should indicate the number of bytes of its own |
3930 | arguments that a function pops on returning, or 0 if the | |
3931 | function pops no arguments and the caller must therefore pop them all | |
3932 | after the function returns. | |
3933 | ||
3934 | @var{fundecl} is a C variable whose value is a tree node that describes | |
3935 | the function in question. Normally it is a node of type | |
3936 | @code{FUNCTION_DECL} that describes the declaration of the function. | |
91d231cb | 3937 | From this you can obtain the @code{DECL_ATTRIBUTES} of the function. |
feca2ed3 JW |
3938 | |
3939 | @var{funtype} is a C variable whose value is a tree node that | |
3940 | describes the function in question. Normally it is a node of type | |
3941 | @code{FUNCTION_TYPE} that describes the data type of the function. | |
3942 | From this it is possible to obtain the data types of the value and | |
3943 | arguments (if known). | |
3944 | ||
861bb6c1 | 3945 | When a call to a library function is being considered, @var{fundecl} |
feca2ed3 JW |
3946 | will contain an identifier node for the library function. Thus, if |
3947 | you need to distinguish among various library functions, you can do so | |
3948 | by their names. Note that ``library function'' in this context means | |
3949 | a function used to perform arithmetic, whose name is known specially | |
3950 | in the compiler and was not mentioned in the C code being compiled. | |
3951 | ||
3952 | @var{stack-size} is the number of bytes of arguments passed on the | |
3953 | stack. If a variable number of bytes is passed, it is zero, and | |
3954 | argument popping will always be the responsibility of the calling function. | |
3955 | ||
8aeea6e6 | 3956 | On the VAX, all functions always pop their arguments, so the definition |
feca2ed3 JW |
3957 | of this macro is @var{stack-size}. On the 68000, using the standard |
3958 | calling convention, no functions pop their arguments, so the value of | |
3959 | the macro is always 0 in this case. But an alternative calling | |
3960 | convention is available in which functions that take a fixed number of | |
3961 | arguments pop them but other functions (such as @code{printf}) pop | |
3962 | nothing (the caller pops all). When this convention is in use, | |
3963 | @var{funtype} is examined to determine whether a function takes a fixed | |
3964 | number of arguments. | |
a2c4f8e0 | 3965 | @end defmac |
fa5322fa | 3966 | |
a2c4f8e0 | 3967 | @defmac CALL_POPS_ARGS (@var{cum}) |
fa5322fa AO |
3968 | A C expression that should indicate the number of bytes a call sequence |
3969 | pops off the stack. It is added to the value of @code{RETURN_POPS_ARGS} | |
3970 | when compiling a function call. | |
3971 | ||
3972 | @var{cum} is the variable in which all arguments to the called function | |
3973 | have been accumulated. | |
3974 | ||
3975 | On certain architectures, such as the SH5, a call trampoline is used | |
3976 | that pops certain registers off the stack, depending on the arguments | |
3977 | that have been passed to the function. Since this is a property of the | |
3978 | call site, not of the called function, @code{RETURN_POPS_ARGS} is not | |
3979 | appropriate. | |
a2c4f8e0 | 3980 | @end defmac |
feca2ed3 JW |
3981 | |
3982 | @node Register Arguments | |
3983 | @subsection Passing Arguments in Registers | |
3984 | @cindex arguments in registers | |
3985 | @cindex registers arguments | |
3986 | ||
3987 | This section describes the macros which let you control how various | |
3988 | types of arguments are passed in registers or how they are arranged in | |
3989 | the stack. | |
3990 | ||
a2c4f8e0 | 3991 | @defmac FUNCTION_ARG (@var{cum}, @var{mode}, @var{type}, @var{named}) |
feca2ed3 JW |
3992 | A C expression that controls whether a function argument is passed |
3993 | in a register, and which register. | |
3994 | ||
3995 | The arguments are @var{cum}, which summarizes all the previous | |
3996 | arguments; @var{mode}, the machine mode of the argument; @var{type}, | |
3997 | the data type of the argument as a tree node or 0 if that is not known | |
3998 | (which happens for C support library functions); and @var{named}, | |
3999 | which is 1 for an ordinary argument and 0 for nameless arguments that | |
4000 | correspond to @samp{@dots{}} in the called function's prototype. | |
3719d27b JO |
4001 | @var{type} can be an incomplete type if a syntax error has previously |
4002 | occurred. | |
feca2ed3 JW |
4003 | |
4004 | The value of the expression is usually either a @code{reg} RTX for the | |
4005 | hard register in which to pass the argument, or zero to pass the | |
4006 | argument on the stack. | |
4007 | ||
8aeea6e6 | 4008 | For machines like the VAX and 68000, where normally all arguments are |
feca2ed3 JW |
4009 | pushed, zero suffices as a definition. |
4010 | ||
161d7b59 | 4011 | The value of the expression can also be a @code{parallel} RTX@. This is |
feca2ed3 | 4012 | used when an argument is passed in multiple locations. The mode of the |
ce376beb | 4013 | @code{parallel} should be the mode of the entire argument. The |
feca2ed3 | 4014 | @code{parallel} holds any number of @code{expr_list} pairs; each one |
f797c10b NC |
4015 | describes where part of the argument is passed. In each |
4016 | @code{expr_list} the first operand must be a @code{reg} RTX for the hard | |
4017 | register in which to pass this part of the argument, and the mode of the | |
4018 | register RTX indicates how large this part of the argument is. The | |
4019 | second operand of the @code{expr_list} is a @code{const_int} which gives | |
4020 | the offset in bytes into the entire argument of where this part starts. | |
02f52e19 | 4021 | As a special exception the first @code{expr_list} in the @code{parallel} |
c980b85b NC |
4022 | RTX may have a first operand of zero. This indicates that the entire |
4023 | argument is also stored on the stack. | |
feca2ed3 | 4024 | |
1cc5e432 GK |
4025 | The last time this macro is called, it is called with @code{MODE == |
4026 | VOIDmode}, and its result is passed to the @code{call} or @code{call_value} | |
4027 | pattern as operands 2 and 3 respectively. | |
4028 | ||
feca2ed3 | 4029 | @cindex @file{stdarg.h} and register arguments |
5490d604 | 4030 | The usual way to make the ISO library @file{stdarg.h} work on a machine |
feca2ed3 JW |
4031 | where some arguments are usually passed in registers, is to cause |
4032 | nameless arguments to be passed on the stack instead. This is done | |
4033 | by making @code{FUNCTION_ARG} return 0 whenever @var{named} is 0. | |
4034 | ||
fe984136 | 4035 | @cindex @code{TARGET_MUST_PASS_IN_STACK}, and @code{FUNCTION_ARG} |
feca2ed3 | 4036 | @cindex @code{REG_PARM_STACK_SPACE}, and @code{FUNCTION_ARG} |
fe984136 | 4037 | You may use the hook @code{targetm.calls.must_pass_in_stack} |
feca2ed3 JW |
4038 | in the definition of this macro to determine if this argument is of a |
4039 | type that must be passed in the stack. If @code{REG_PARM_STACK_SPACE} | |
df2a54e9 | 4040 | is not defined and @code{FUNCTION_ARG} returns nonzero for such an |
feca2ed3 JW |
4041 | argument, the compiler will abort. If @code{REG_PARM_STACK_SPACE} is |
4042 | defined, the argument will be computed in the stack and then loaded into | |
4043 | a register. | |
a2c4f8e0 | 4044 | @end defmac |
feca2ed3 | 4045 | |
fe984136 RH |
4046 | @deftypefn {Target Hook} bool TARGET_MUST_PASS_IN_STACK (enum machine_mode @var{mode}, tree @var{type}) |
4047 | This target hook should return @code{true} if we should not pass @var{type} | |
4048 | solely in registers. The file @file{expr.h} defines a | |
d9a4ee00 JL |
4049 | definition that is usually appropriate, refer to @file{expr.h} for additional |
4050 | documentation. | |
fe984136 | 4051 | @end deftypefn |
d9a4ee00 | 4052 | |
a2c4f8e0 | 4053 | @defmac FUNCTION_INCOMING_ARG (@var{cum}, @var{mode}, @var{type}, @var{named}) |
feca2ed3 JW |
4054 | Define this macro if the target machine has ``register windows'', so |
4055 | that the register in which a function sees an arguments is not | |
4056 | necessarily the same as the one in which the caller passed the | |
4057 | argument. | |
4058 | ||
4059 | For such machines, @code{FUNCTION_ARG} computes the register in which | |
4060 | the caller passes the value, and @code{FUNCTION_INCOMING_ARG} should | |
4061 | be defined in a similar fashion to tell the function being called | |
4062 | where the arguments will arrive. | |
4063 | ||
4064 | If @code{FUNCTION_INCOMING_ARG} is not defined, @code{FUNCTION_ARG} | |
bd819a4a | 4065 | serves both purposes. |
a2c4f8e0 | 4066 | @end defmac |
feca2ed3 | 4067 | |
78a52f11 RH |
4068 | @deftypefn {Target Hook} int TARGET_ARG_PARTIAL_BYTES (CUMULATIVE_ARGS *@var{cum}, enum machine_mode @var{mode}, tree @var{type}, bool @var{named}) |
4069 | This target hook returns the number of bytes at the beginning of an | |
4070 | argument that must be put in registers. The value must be zero for | |
feca2ed3 JW |
4071 | arguments that are passed entirely in registers or that are entirely |
4072 | pushed on the stack. | |
4073 | ||
4074 | On some machines, certain arguments must be passed partially in | |
4075 | registers and partially in memory. On these machines, typically the | |
78a52f11 | 4076 | first few words of arguments are passed in registers, and the rest |
feca2ed3 JW |
4077 | on the stack. If a multi-word argument (a @code{double} or a |
4078 | structure) crosses that boundary, its first few words must be passed | |
4079 | in registers and the rest must be pushed. This macro tells the | |
78a52f11 | 4080 | compiler when this occurs, and how many bytes should go in registers. |
feca2ed3 JW |
4081 | |
4082 | @code{FUNCTION_ARG} for these arguments should return the first | |
4083 | register to be used by the caller for this argument; likewise | |
4084 | @code{FUNCTION_INCOMING_ARG}, for the called function. | |
78a52f11 | 4085 | @end deftypefn |
feca2ed3 | 4086 | |
8cd5a4e0 | 4087 | @deftypefn {Target Hook} bool TARGET_PASS_BY_REFERENCE (CUMULATIVE_ARGS *@var{cum}, enum machine_mode @var{mode}, tree @var{type}, bool @var{named}) |
f676971a | 4088 | This target hook should return @code{true} if an argument at the |
8cd5a4e0 | 4089 | position indicated by @var{cum} should be passed by reference. This |
f676971a | 4090 | predicate is queried after target independent reasons for being |
8cd5a4e0 RH |
4091 | passed by reference, such as @code{TREE_ADDRESSABLE (type)}. |
4092 | ||
4093 | If the hook returns true, a copy of that argument is made in memory and a | |
feca2ed3 JW |
4094 | pointer to the argument is passed instead of the argument itself. |
4095 | The pointer is passed in whatever way is appropriate for passing a pointer | |
4096 | to that type. | |
8cd5a4e0 | 4097 | @end deftypefn |
feca2ed3 | 4098 | |
6cdd5672 RH |
4099 | @deftypefn {Target Hook} bool TARGET_CALLEE_COPIES (CUMULATIVE_ARGS *@var{cum}, enum machine_mode @var{mode}, tree @var{type}, bool @var{named}) |
4100 | The function argument described by the parameters to this hook is | |
4101 | known to be passed by reference. The hook should return true if the | |
4102 | function argument should be copied by the callee instead of copied | |
4103 | by the caller. | |
4104 | ||
a1c496cb | 4105 | For any argument for which the hook returns true, if it can be |
6cdd5672 RH |
4106 | determined that the argument is not modified, then a copy need |
4107 | not be generated. | |
4108 | ||
4109 | The default version of this hook always returns false. | |
4110 | @end deftypefn | |
feca2ed3 | 4111 | |
a2c4f8e0 | 4112 | @defmac CUMULATIVE_ARGS |
feca2ed3 JW |
4113 | A C type for declaring a variable that is used as the first argument of |
4114 | @code{FUNCTION_ARG} and other related values. For some target machines, | |
4115 | the type @code{int} suffices and can hold the number of bytes of | |
4116 | argument so far. | |
4117 | ||
4118 | There is no need to record in @code{CUMULATIVE_ARGS} anything about the | |
4119 | arguments that have been passed on the stack. The compiler has other | |
4120 | variables to keep track of that. For target machines on which all | |
4121 | arguments are passed on the stack, there is no need to store anything in | |
4122 | @code{CUMULATIVE_ARGS}; however, the data structure must exist and | |
4123 | should not be empty, so use @code{int}. | |
a2c4f8e0 | 4124 | @end defmac |
feca2ed3 | 4125 | |
7c800926 KT |
4126 | @defmac OVERRIDE_ABI_FORMAT (@var{fndecl}) |
4127 | If defined, this macro is called before generating any code for a | |
4128 | function, but after the @var{cfun} descriptor for the function has been | |
4129 | created. The back end may use this macro to update @var{cfun} to | |
4130 | reflect an ABI other than that which would normally be used by default. | |
4131 | If the compiler is generating code for a compiler-generated function, | |
4132 | @var{fndecl} may be @code{NULL}. | |
4133 | @end defmac | |
4134 | ||
0f6937fe | 4135 | @defmac INIT_CUMULATIVE_ARGS (@var{cum}, @var{fntype}, @var{libname}, @var{fndecl}, @var{n_named_args}) |
a2c4f8e0 ZW |
4136 | A C statement (sans semicolon) for initializing the variable |
4137 | @var{cum} for the state at the beginning of the argument list. The | |
4138 | variable has type @code{CUMULATIVE_ARGS}. The value of @var{fntype} | |
4139 | is the tree node for the data type of the function which will receive | |
4140 | the args, or 0 if the args are to a compiler support library function. | |
4141 | For direct calls that are not libcalls, @var{fndecl} contain the | |
4142 | declaration node of the function. @var{fndecl} is also set when | |
4143 | @code{INIT_CUMULATIVE_ARGS} is used to find arguments for the function | |
0f6937fe AM |
4144 | being compiled. @var{n_named_args} is set to the number of named |
4145 | arguments, including a structure return address if it is passed as a | |
4146 | parameter, when making a call. When processing incoming arguments, | |
78466c0e | 4147 | @var{n_named_args} is set to @minus{}1. |
feca2ed3 JW |
4148 | |
4149 | When processing a call to a compiler support library function, | |
4150 | @var{libname} identifies which one. It is a @code{symbol_ref} rtx which | |
4151 | contains the name of the function, as a string. @var{libname} is 0 when | |
4152 | an ordinary C function call is being processed. Thus, each time this | |
4153 | macro is called, either @var{libname} or @var{fntype} is nonzero, but | |
4154 | never both of them at once. | |
a2c4f8e0 | 4155 | @end defmac |
feca2ed3 | 4156 | |
a2c4f8e0 | 4157 | @defmac INIT_CUMULATIVE_LIBCALL_ARGS (@var{cum}, @var{mode}, @var{libname}) |
97fc4caf AO |
4158 | Like @code{INIT_CUMULATIVE_ARGS} but only used for outgoing libcalls, |
4159 | it gets a @code{MODE} argument instead of @var{fntype}, that would be | |
4160 | @code{NULL}. @var{indirect} would always be zero, too. If this macro | |
4161 | is not defined, @code{INIT_CUMULATIVE_ARGS (cum, NULL_RTX, libname, | |
4162 | 0)} is used instead. | |
a2c4f8e0 | 4163 | @end defmac |
97fc4caf | 4164 | |
a2c4f8e0 | 4165 | @defmac INIT_CUMULATIVE_INCOMING_ARGS (@var{cum}, @var{fntype}, @var{libname}) |
feca2ed3 JW |
4166 | Like @code{INIT_CUMULATIVE_ARGS} but overrides it for the purposes of |
4167 | finding the arguments for the function being compiled. If this macro is | |
4168 | undefined, @code{INIT_CUMULATIVE_ARGS} is used instead. | |
4169 | ||
4170 | The value passed for @var{libname} is always 0, since library routines | |
161d7b59 | 4171 | with special calling conventions are never compiled with GCC@. The |
feca2ed3 JW |
4172 | argument @var{libname} exists for symmetry with |
4173 | @code{INIT_CUMULATIVE_ARGS}. | |
4174 | @c could use "this macro" in place of @code{INIT_CUMULATIVE_ARGS}, maybe. | |
4175 | @c --mew 5feb93 i switched the order of the sentences. --mew 10feb93 | |
a2c4f8e0 | 4176 | @end defmac |
feca2ed3 | 4177 | |
a2c4f8e0 | 4178 | @defmac FUNCTION_ARG_ADVANCE (@var{cum}, @var{mode}, @var{type}, @var{named}) |
feca2ed3 JW |
4179 | A C statement (sans semicolon) to update the summarizer variable |
4180 | @var{cum} to advance past an argument in the argument list. The | |
4181 | values @var{mode}, @var{type} and @var{named} describe that argument. | |
4182 | Once this is done, the variable @var{cum} is suitable for analyzing | |
bd819a4a | 4183 | the @emph{following} argument with @code{FUNCTION_ARG}, etc. |
feca2ed3 JW |
4184 | |
4185 | This macro need not do anything if the argument in question was passed | |
4186 | on the stack. The compiler knows how to track the amount of stack space | |
4187 | used for arguments without any special help. | |
a2c4f8e0 | 4188 | @end defmac |
feca2ed3 | 4189 | |
099590dc MM |
4190 | |
4191 | @defmac FUNCTION_ARG_OFFSET (@var{mode}, @var{type}) | |
4192 | If defined, a C expression that is the number of bytes to add to the | |
4193 | offset of the argument passed in memory. This is needed for the SPU, | |
4194 | which passes @code{char} and @code{short} arguments in the preferred | |
4195 | slot that is in the middle of the quad word instead of starting at the | |
4196 | top. | |
4197 | @end defmac | |
4198 | ||
a2c4f8e0 | 4199 | @defmac FUNCTION_ARG_PADDING (@var{mode}, @var{type}) |
feca2ed3 JW |
4200 | If defined, a C expression which determines whether, and in which direction, |
4201 | to pad out an argument with extra space. The value should be of type | |
4202 | @code{enum direction}: either @code{upward} to pad above the argument, | |
4203 | @code{downward} to pad below, or @code{none} to inhibit padding. | |
4204 | ||
4205 | The @emph{amount} of padding is always just enough to reach the next | |
4206 | multiple of @code{FUNCTION_ARG_BOUNDARY}; this macro does not control | |
4207 | it. | |
4208 | ||
4209 | This macro has a default definition which is right for most systems. | |
4210 | For little-endian machines, the default is to pad upward. For | |
4211 | big-endian machines, the default is to pad downward for an argument of | |
4212 | constant size shorter than an @code{int}, and upward otherwise. | |
a2c4f8e0 | 4213 | @end defmac |
feca2ed3 | 4214 | |
a2c4f8e0 | 4215 | @defmac PAD_VARARGS_DOWN |
02f52e19 AJ |
4216 | If defined, a C expression which determines whether the default |
4217 | implementation of va_arg will attempt to pad down before reading the | |
5e4f6244 CP |
4218 | next argument, if that argument is smaller than its aligned space as |
4219 | controlled by @code{PARM_BOUNDARY}. If this macro is not defined, all such | |
4220 | arguments are padded down if @code{BYTES_BIG_ENDIAN} is true. | |
a2c4f8e0 | 4221 | @end defmac |
5e4f6244 | 4222 | |
6e985040 AM |
4223 | @defmac BLOCK_REG_PADDING (@var{mode}, @var{type}, @var{first}) |
4224 | Specify padding for the last element of a block move between registers and | |
4225 | memory. @var{first} is nonzero if this is the only element. Defining this | |
4226 | macro allows better control of register function parameters on big-endian | |
4227 | machines, without using @code{PARALLEL} rtl. In particular, | |
4228 | @code{MUST_PASS_IN_STACK} need not test padding and mode of types in | |
4229 | registers, as there is no longer a "wrong" part of a register; For example, | |
4230 | a three byte aggregate may be passed in the high part of a register if so | |
4231 | required. | |
4232 | @end defmac | |
4233 | ||
a2c4f8e0 | 4234 | @defmac FUNCTION_ARG_BOUNDARY (@var{mode}, @var{type}) |
feca2ed3 JW |
4235 | If defined, a C expression that gives the alignment boundary, in bits, |
4236 | of an argument with the specified mode and type. If it is not defined, | |
4237 | @code{PARM_BOUNDARY} is used for all arguments. | |
a2c4f8e0 | 4238 | @end defmac |
feca2ed3 | 4239 | |
a2c4f8e0 | 4240 | @defmac FUNCTION_ARG_REGNO_P (@var{regno}) |
feca2ed3 JW |
4241 | A C expression that is nonzero if @var{regno} is the number of a hard |
4242 | register in which function arguments are sometimes passed. This does | |
4243 | @emph{not} include implicit arguments such as the static chain and | |
4244 | the structure-value address. On many machines, no registers can be | |
4245 | used for this purpose since all function arguments are pushed on the | |
4246 | stack. | |
a2c4f8e0 | 4247 | @end defmac |
bb1b857a | 4248 | |
42ba5130 RH |
4249 | @deftypefn {Target Hook} bool TARGET_SPLIT_COMPLEX_ARG (tree @var{type}) |
4250 | This hook should return true if parameter of type @var{type} are passed | |
4251 | as two scalar parameters. By default, GCC will attempt to pack complex | |
4252 | arguments into the target's word size. Some ABIs require complex arguments | |
4253 | to be split and treated as their individual components. For example, on | |
4254 | AIX64, complex floats should be passed in a pair of floating point | |
4255 | registers, even though a complex float would fit in one 64-bit floating | |
4256 | point register. | |
4257 | ||
4258 | The default value of this hook is @code{NULL}, which is treated as always | |
4259 | false. | |
4260 | @end deftypefn | |
ded9bf77 | 4261 | |
d3da4d14 RH |
4262 | @deftypefn {Target Hook} tree TARGET_BUILD_BUILTIN_VA_LIST (void) |
4263 | This hook returns a type node for @code{va_list} for the target. | |
4264 | The default version of the hook returns @code{void*}. | |
4265 | @end deftypefn | |
4266 | ||
35cbb299 KT |
4267 | @deftypefn {Target Hook} tree TARGET_FN_ABI_VA_LIST (tree @var{fndecl}) |
4268 | This hook returns the va_list type of the calling convention specified by | |
4269 | @var{fndecl}. | |
4270 | The default version of this hook returns @code{va_list_type_node}. | |
4271 | @end deftypefn | |
4272 | ||
4273 | @deftypefn {Target Hook} tree TARGET_CANONICAL_VA_LIST_TYPE (tree @var{type}) | |
4274 | This hook returns the va_list type of the calling convention specified by the | |
4275 | type of @var{type}. If @var{type} is not a valid va_list type, it returns | |
4276 | @code{NULL_TREE}. | |
4277 | @end deftypefn | |
4278 | ||
23a60a04 JM |
4279 | @deftypefn {Target Hook} tree TARGET_GIMPLIFY_VA_ARG_EXPR (tree @var{valist}, tree @var{type}, tree *@var{pre_p}, tree *@var{post_p}) |
4280 | This hook performs target-specific gimplification of | |
4281 | @code{VA_ARG_EXPR}. The first two parameters correspond to the | |
4282 | arguments to @code{va_arg}; the latter two are as in | |
4283 | @code{gimplify.c:gimplify_expr}. | |
23a60a04 JM |
4284 | @end deftypefn |
4285 | ||
e09ec166 EC |
4286 | @deftypefn {Target Hook} bool TARGET_VALID_POINTER_MODE (enum machine_mode @var{mode}) |
4287 | Define this to return nonzero if the port can handle pointers | |
4288 | with machine mode @var{mode}. The default version of this | |
4289 | hook returns true for both @code{ptr_mode} and @code{Pmode}. | |
4290 | @end deftypefn | |
4291 | ||
6dd53648 RH |
4292 | @deftypefn {Target Hook} bool TARGET_SCALAR_MODE_SUPPORTED_P (enum machine_mode @var{mode}) |
4293 | Define this to return nonzero if the port is prepared to handle | |
4294 | insns involving scalar mode @var{mode}. For a scalar mode to be | |
4295 | considered supported, all the basic arithmetic and comparisons | |
4296 | must work. | |
4297 | ||
4298 | The default version of this hook returns true for any mode | |
4299 | required to handle the basic C types (as defined by the port). | |
4300 | Included here are the double-word arithmetic supported by the | |
4301 | code in @file{optabs.c}. | |
4302 | @end deftypefn | |
4303 | ||
f676971a EC |
4304 | @deftypefn {Target Hook} bool TARGET_VECTOR_MODE_SUPPORTED_P (enum machine_mode @var{mode}) |
4305 | Define this to return nonzero if the port is prepared to handle | |
4306 | insns involving vector mode @var{mode}. At the very least, it | |
4307 | must have move patterns for this mode. | |
4308 | @end deftypefn | |
4309 | ||
feca2ed3 JW |
4310 | @node Scalar Return |
4311 | @subsection How Scalar Function Values Are Returned | |
4312 | @cindex return values in registers | |
4313 | @cindex values, returned by functions | |
4314 | @cindex scalars, returned as values | |
4315 | ||
4316 | This section discusses the macros that control returning scalars as | |
4317 | values---values that can fit in registers. | |
4318 | ||
0b35aac2 | 4319 | @deftypefn {Target Hook} rtx TARGET_FUNCTION_VALUE (tree @var{ret_type}, tree @var{fn_decl_or_type}, bool @var{outgoing}) |
1b03c58a RG |
4320 | |
4321 | Define this to return an RTX representing the place where a function | |
4322 | returns or receives a value of data type @var{ret_type}, a tree node | |
e4ae5e77 | 4323 | representing a data type. @var{fn_decl_or_type} is a tree node |
1b03c58a RG |
4324 | representing @code{FUNCTION_DECL} or @code{FUNCTION_TYPE} of a |
4325 | function being called. If @var{outgoing} is false, the hook should | |
4326 | compute the register in which the caller will see the return value. | |
4327 | Otherwise, the hook should return an RTX representing the place where | |
4328 | a function returns a value. | |
4329 | ||
4330 | On many machines, only @code{TYPE_MODE (@var{ret_type})} is relevant. | |
4331 | (Actually, on most machines, scalar values are returned in the same | |
4332 | place regardless of mode.) The value of the expression is usually a | |
4333 | @code{reg} RTX for the hard register where the return value is stored. | |
4334 | The value can also be a @code{parallel} RTX, if the return value is in | |
4335 | multiple places. See @code{FUNCTION_ARG} for an explanation of the | |
576c9028 KH |
4336 | @code{parallel} form. Note that the callee will populate every |
4337 | location specified in the @code{parallel}, but if the first element of | |
4338 | the @code{parallel} contains the whole return value, callers will use | |
4339 | that element as the canonical location and ignore the others. The m68k | |
4340 | port uses this type of @code{parallel} to return pointers in both | |
4341 | @samp{%a0} (the canonical location) and @samp{%d0}. | |
1b03c58a RG |
4342 | |
4343 | If @code{TARGET_PROMOTE_FUNCTION_RETURN} returns true, you must apply | |
4344 | the same promotion rules specified in @code{PROMOTE_MODE} if | |
4345 | @var{valtype} is a scalar type. | |
feca2ed3 JW |
4346 | |
4347 | If the precise function being called is known, @var{func} is a tree | |
4348 | node (@code{FUNCTION_DECL}) for it; otherwise, @var{func} is a null | |
4349 | pointer. This makes it possible to use a different value-returning | |
4350 | convention for specific functions when all their calls are | |
bd819a4a | 4351 | known. |
feca2ed3 | 4352 | |
1b03c58a RG |
4353 | Some target machines have ``register windows'' so that the register in |
4354 | which a function returns its value is not the same as the one in which | |
4355 | the caller sees the value. For such machines, you should return | |
4356 | different RTX depending on @var{outgoing}. | |
4357 | ||
4358 | @code{TARGET_FUNCTION_VALUE} is not used for return values with | |
4359 | aggregate data types, because these are returned in another way. See | |
cea28603 | 4360 | @code{TARGET_STRUCT_VALUE_RTX} and related macros, below. |
1b03c58a RG |
4361 | @end deftypefn |
4362 | ||
4363 | @defmac FUNCTION_VALUE (@var{valtype}, @var{func}) | |
4364 | This macro has been deprecated. Use @code{TARGET_FUNCTION_VALUE} for | |
4365 | a new target instead. | |
a2c4f8e0 | 4366 | @end defmac |
feca2ed3 | 4367 | |
a2c4f8e0 | 4368 | @defmac FUNCTION_OUTGOING_VALUE (@var{valtype}, @var{func}) |
1b03c58a RG |
4369 | This macro has been deprecated. Use @code{TARGET_FUNCTION_VALUE} for |
4370 | a new target instead. | |
a2c4f8e0 | 4371 | @end defmac |
feca2ed3 | 4372 | |
a2c4f8e0 | 4373 | @defmac LIBCALL_VALUE (@var{mode}) |
feca2ed3 | 4374 | A C expression to create an RTX representing the place where a library |
dc672951 | 4375 | function returns a value of mode @var{mode}. |
feca2ed3 JW |
4376 | |
4377 | Note that ``library function'' in this context means a compiler | |
4378 | support routine, used to perform arithmetic, whose name is known | |
4379 | specially by the compiler and was not mentioned in the C code being | |
4380 | compiled. | |
a2c4f8e0 | 4381 | @end defmac |
feca2ed3 | 4382 | |
a2c4f8e0 | 4383 | @defmac FUNCTION_VALUE_REGNO_P (@var{regno}) |
feca2ed3 JW |
4384 | A C expression that is nonzero if @var{regno} is the number of a hard |
4385 | register in which the values of called function may come back. | |
4386 | ||
4387 | A register whose use for returning values is limited to serving as the | |
4388 | second of a pair (for a value of type @code{double}, say) need not be | |
4389 | recognized by this macro. So for most machines, this definition | |
4390 | suffices: | |
4391 | ||
3ab51846 | 4392 | @smallexample |
feca2ed3 | 4393 | #define FUNCTION_VALUE_REGNO_P(N) ((N) == 0) |
3ab51846 | 4394 | @end smallexample |
feca2ed3 JW |
4395 | |
4396 | If the machine has register windows, so that the caller and the called | |
4397 | function use different registers for the return value, this macro | |
4398 | should recognize only the caller's register numbers. | |
a2c4f8e0 | 4399 | @end defmac |
feca2ed3 | 4400 | |
35cbb299 KT |
4401 | @defmac TARGET_ENUM_VA_LIST (@var{idx}, @var{pname}, @var{ptype}) |
4402 | This target macro is used in function @code{c_common_nodes_and_builtins} | |
4403 | to iterate through the target specific builtin types for va_list. The | |
4404 | variable @var{idx} is used as iterator. @var{pname} has to be a pointer | |
4405 | to a @code{const char *} and @var{ptype} a pointer to a @code{tree} typed | |
4406 | variable. | |
4407 | The arguments @var{pname} and @var{ptype} are used to store the result of | |
4408 | this macro and are set to the name of the va_list builtin type and its | |
4409 | internal type. | |
4410 | If the return value of this macro is zero, then there is no more element. | |
4411 | Otherwise the @var{IDX} should be increased for the next call of this | |
4412 | macro to iterate through all types. | |
4413 | @end defmac | |
4414 | ||
a2c4f8e0 | 4415 | @defmac APPLY_RESULT_SIZE |
feca2ed3 JW |
4416 | Define this macro if @samp{untyped_call} and @samp{untyped_return} |
4417 | need more space than is implied by @code{FUNCTION_VALUE_REGNO_P} for | |
4418 | saving and restoring an arbitrary return value. | |
a2c4f8e0 | 4419 | @end defmac |
feca2ed3 | 4420 | |
c988af2b RS |
4421 | @deftypefn {Target Hook} bool TARGET_RETURN_IN_MSB (tree @var{type}) |
4422 | This hook should return true if values of type @var{type} are returned | |
4423 | at the most significant end of a register (in other words, if they are | |
4424 | padded at the least significant end). You can assume that @var{type} | |
4425 | is returned in a register; the caller is required to check this. | |
4426 | ||
1b03c58a RG |
4427 | Note that the register provided by @code{TARGET_FUNCTION_VALUE} must |
4428 | be able to hold the complete return value. For example, if a 1-, 2- | |
4429 | or 3-byte structure is returned at the most significant end of a | |
4430 | 4-byte register, @code{TARGET_FUNCTION_VALUE} should provide an | |
4431 | @code{SImode} rtx. | |
c988af2b RS |
4432 | @end deftypefn |
4433 | ||
feca2ed3 JW |
4434 | @node Aggregate Return |
4435 | @subsection How Large Values Are Returned | |
4436 | @cindex aggregates as return values | |
4437 | @cindex large return values | |
4438 | @cindex returning aggregate values | |
4439 | @cindex structure value address | |
4440 | ||
4441 | When a function value's mode is @code{BLKmode} (and in some other | |
1b03c58a RG |
4442 | cases), the value is not returned according to |
4443 | @code{TARGET_FUNCTION_VALUE} (@pxref{Scalar Return}). Instead, the | |
4444 | caller passes the address of a block of memory in which the value | |
4445 | should be stored. This address is called the @dfn{structure value | |
4446 | address}. | |
feca2ed3 JW |
4447 | |
4448 | This section describes how to control returning structure values in | |
4449 | memory. | |
4450 | ||
d624465f | 4451 | @deftypefn {Target Hook} bool TARGET_RETURN_IN_MEMORY (tree @var{type}, tree @var{fntype}) |
61f71b34 DD |
4452 | This target hook should return a nonzero value to say to return the |
4453 | function value in memory, just as large structures are always returned. | |
4454 | Here @var{type} will be the data type of the value, and @var{fntype} | |
4455 | will be the type of the function doing the returning, or @code{NULL} for | |
4456 | libcalls. | |
feca2ed3 JW |
4457 | |
4458 | Note that values of mode @code{BLKmode} must be explicitly handled | |
61f71b34 | 4459 | by this function. Also, the option @option{-fpcc-struct-return} |
feca2ed3 | 4460 | takes effect regardless of this macro. On most systems, it is |
61f71b34 | 4461 | possible to leave the hook undefined; this causes a default |
feca2ed3 JW |
4462 | definition to be used, whose value is the constant 1 for @code{BLKmode} |
4463 | values, and 0 otherwise. | |
4464 | ||
61f71b34 | 4465 | Do not use this hook to indicate that structures and unions should always |
feca2ed3 JW |
4466 | be returned in memory. You should instead use @code{DEFAULT_PCC_STRUCT_RETURN} |
4467 | to indicate this. | |
61f71b34 | 4468 | @end deftypefn |
feca2ed3 | 4469 | |
a2c4f8e0 | 4470 | @defmac DEFAULT_PCC_STRUCT_RETURN |
feca2ed3 JW |
4471 | Define this macro to be 1 if all structure and union return values must be |
4472 | in memory. Since this results in slower code, this should be defined | |
161d7b59 | 4473 | only if needed for compatibility with other compilers or with an ABI@. |
feca2ed3 | 4474 | If you define this macro to be 0, then the conventions used for structure |
d624465f KH |
4475 | and union return values are decided by the @code{TARGET_RETURN_IN_MEMORY} |
4476 | target hook. | |
feca2ed3 JW |
4477 | |
4478 | If not defined, this defaults to the value 1. | |
a2c4f8e0 | 4479 | @end defmac |
feca2ed3 | 4480 | |
61f71b34 DD |
4481 | @deftypefn {Target Hook} rtx TARGET_STRUCT_VALUE_RTX (tree @var{fndecl}, int @var{incoming}) |
4482 | This target hook should return the location of the structure value | |
4483 | address (normally a @code{mem} or @code{reg}), or 0 if the address is | |
4484 | passed as an ``invisible'' first argument. Note that @var{fndecl} may | |
1f6acb82 KH |
4485 | be @code{NULL}, for libcalls. You do not need to define this target |
4486 | hook if the address is always passed as an ``invisible'' first | |
4487 | argument. | |
feca2ed3 | 4488 | |
feca2ed3 JW |
4489 | On some architectures the place where the structure value address |
4490 | is found by the called function is not the same place that the | |
4491 | caller put it. This can be due to register windows, or it could | |
4492 | be because the function prologue moves it to a different place. | |
2225b57c CD |
4493 | @var{incoming} is @code{1} or @code{2} when the location is needed in |
4494 | the context of the called function, and @code{0} in the context of | |
61f71b34 | 4495 | the caller. |
feca2ed3 | 4496 | |
917f1b7e | 4497 | If @var{incoming} is nonzero and the address is to be found on the |
2225b57c CD |
4498 | stack, return a @code{mem} which refers to the frame pointer. If |
4499 | @var{incoming} is @code{2}, the result is being used to fetch the | |
64ee9490 | 4500 | structure value address at the beginning of a function. If you need |
2225b57c | 4501 | to emit adjusting code, you should do it at this point. |
61f71b34 | 4502 | @end deftypefn |
feca2ed3 | 4503 | |
a2c4f8e0 | 4504 | @defmac PCC_STATIC_STRUCT_RETURN |
feca2ed3 JW |
4505 | Define this macro if the usual system convention on the target machine |
4506 | for returning structures and unions is for the called function to return | |
4507 | the address of a static variable containing the value. | |
4508 | ||
4509 | Do not define this if the usual system convention is for the caller to | |
4510 | pass an address to the subroutine. | |
4511 | ||
630d3d5a JM |
4512 | This macro has effect in @option{-fpcc-struct-return} mode, but it does |
4513 | nothing when you use @option{-freg-struct-return} mode. | |
a2c4f8e0 | 4514 | @end defmac |
feca2ed3 JW |
4515 | |
4516 | @node Caller Saves | |
4517 | @subsection Caller-Saves Register Allocation | |
4518 | ||
a3a15b4d | 4519 | If you enable it, GCC can save registers around function calls. This |
feca2ed3 JW |
4520 | makes it possible to use call-clobbered registers to hold variables that |
4521 | must live across calls. | |
4522 | ||
a2c4f8e0 | 4523 | @defmac CALLER_SAVE_PROFITABLE (@var{refs}, @var{calls}) |
feca2ed3 JW |
4524 | A C expression to determine whether it is worthwhile to consider placing |
4525 | a pseudo-register in a call-clobbered hard register and saving and | |
4526 | restoring it around each function call. The expression should be 1 when | |
4527 | this is worth doing, and 0 otherwise. | |
4528 | ||
4529 | If you don't define this macro, a default is used which is good on most | |
4530 | machines: @code{4 * @var{calls} < @var{refs}}. | |
a2c4f8e0 | 4531 | @end defmac |
8d5c8167 | 4532 | |
a2c4f8e0 | 4533 | @defmac HARD_REGNO_CALLER_SAVE_MODE (@var{regno}, @var{nregs}) |
8d5c8167 JL |
4534 | A C expression specifying which mode is required for saving @var{nregs} |
4535 | of a pseudo-register in call-clobbered hard register @var{regno}. If | |
4536 | @var{regno} is unsuitable for caller save, @code{VOIDmode} should be | |
4537 | returned. For most machines this macro need not be defined since GCC | |
4538 | will select the smallest suitable mode. | |
a2c4f8e0 | 4539 | @end defmac |
feca2ed3 JW |
4540 | |
4541 | @node Function Entry | |
4542 | @subsection Function Entry and Exit | |
4543 | @cindex function entry and exit | |
4544 | @cindex prologue | |
4545 | @cindex epilogue | |
4546 | ||
4547 | This section describes the macros that output function entry | |
4548 | (@dfn{prologue}) and exit (@dfn{epilogue}) code. | |
4549 | ||
08c148a8 NB |
4550 | @deftypefn {Target Hook} void TARGET_ASM_FUNCTION_PROLOGUE (FILE *@var{file}, HOST_WIDE_INT @var{size}) |
4551 | If defined, a function that outputs the assembler code for entry to a | |
feca2ed3 JW |
4552 | function. The prologue is responsible for setting up the stack frame, |
4553 | initializing the frame pointer register, saving registers that must be | |
4554 | saved, and allocating @var{size} additional bytes of storage for the | |
4555 | local variables. @var{size} is an integer. @var{file} is a stdio | |
4556 | stream to which the assembler code should be output. | |
4557 | ||
4558 | The label for the beginning of the function need not be output by this | |
4559 | macro. That has already been done when the macro is run. | |
4560 | ||
4561 | @findex regs_ever_live | |
4562 | To determine which registers to save, the macro can refer to the array | |
4563 | @code{regs_ever_live}: element @var{r} is nonzero if hard register | |
4564 | @var{r} is used anywhere within the function. This implies the function | |
4565 | prologue should save register @var{r}, provided it is not one of the | |
08c148a8 | 4566 | call-used registers. (@code{TARGET_ASM_FUNCTION_EPILOGUE} must likewise use |
feca2ed3 JW |
4567 | @code{regs_ever_live}.) |
4568 | ||
4569 | On machines that have ``register windows'', the function entry code does | |
4570 | not save on the stack the registers that are in the windows, even if | |
4571 | they are supposed to be preserved by function calls; instead it takes | |
4572 | appropriate steps to ``push'' the register stack, if any non-call-used | |
4573 | registers are used in the function. | |
4574 | ||
4575 | @findex frame_pointer_needed | |
4576 | On machines where functions may or may not have frame-pointers, the | |
4577 | function entry code must vary accordingly; it must set up the frame | |
4578 | pointer if one is wanted, and not otherwise. To determine whether a | |
4579 | frame pointer is in wanted, the macro can refer to the variable | |
4580 | @code{frame_pointer_needed}. The variable's value will be 1 at run | |
4581 | time in a function that needs a frame pointer. @xref{Elimination}. | |
4582 | ||
4583 | The function entry code is responsible for allocating any stack space | |
4584 | required for the function. This stack space consists of the regions | |
4585 | listed below. In most cases, these regions are allocated in the | |
4586 | order listed, with the last listed region closest to the top of the | |
4587 | stack (the lowest address if @code{STACK_GROWS_DOWNWARD} is defined, and | |
4588 | the highest address if it is not defined). You can use a different order | |
4589 | for a machine if doing so is more convenient or required for | |
4590 | compatibility reasons. Except in cases where required by standard | |
4591 | or by a debugger, there is no reason why the stack layout used by GCC | |
4592 | need agree with that used by other compilers for a machine. | |
08c148a8 NB |
4593 | @end deftypefn |
4594 | ||
17b53c33 NB |
4595 | @deftypefn {Target Hook} void TARGET_ASM_FUNCTION_END_PROLOGUE (FILE *@var{file}) |
4596 | If defined, a function that outputs assembler code at the end of a | |
4597 | prologue. This should be used when the function prologue is being | |
4598 | emitted as RTL, and you have some extra assembler that needs to be | |
4599 | emitted. @xref{prologue instruction pattern}. | |
4600 | @end deftypefn | |
4601 | ||
4602 | @deftypefn {Target Hook} void TARGET_ASM_FUNCTION_BEGIN_EPILOGUE (FILE *@var{file}) | |
4603 | If defined, a function that outputs assembler code at the start of an | |
4604 | epilogue. This should be used when the function epilogue is being | |
4605 | emitted as RTL, and you have some extra assembler that needs to be | |
4606 | emitted. @xref{epilogue instruction pattern}. | |
4607 | @end deftypefn | |
4608 | ||
08c148a8 NB |
4609 | @deftypefn {Target Hook} void TARGET_ASM_FUNCTION_EPILOGUE (FILE *@var{file}, HOST_WIDE_INT @var{size}) |
4610 | If defined, a function that outputs the assembler code for exit from a | |
4611 | function. The epilogue is responsible for restoring the saved | |
4612 | registers and stack pointer to their values when the function was | |
4613 | called, and returning control to the caller. This macro takes the | |
4614 | same arguments as the macro @code{TARGET_ASM_FUNCTION_PROLOGUE}, and the | |
4615 | registers to restore are determined from @code{regs_ever_live} and | |
4616 | @code{CALL_USED_REGISTERS} in the same way. | |
4617 | ||
4618 | On some machines, there is a single instruction that does all the work | |
4619 | of returning from the function. On these machines, give that | |
4620 | instruction the name @samp{return} and do not define the macro | |
4621 | @code{TARGET_ASM_FUNCTION_EPILOGUE} at all. | |
4622 | ||
4623 | Do not define a pattern named @samp{return} if you want the | |
4624 | @code{TARGET_ASM_FUNCTION_EPILOGUE} to be used. If you want the target | |
4625 | switches to control whether return instructions or epilogues are used, | |
4626 | define a @samp{return} pattern with a validity condition that tests the | |
4627 | target switches appropriately. If the @samp{return} pattern's validity | |
4628 | condition is false, epilogues will be used. | |
4629 | ||
4630 | On machines where functions may or may not have frame-pointers, the | |
4631 | function exit code must vary accordingly. Sometimes the code for these | |
4632 | two cases is completely different. To determine whether a frame pointer | |
4633 | is wanted, the macro can refer to the variable | |
4634 | @code{frame_pointer_needed}. The variable's value will be 1 when compiling | |
4635 | a function that needs a frame pointer. | |
4636 | ||
4637 | Normally, @code{TARGET_ASM_FUNCTION_PROLOGUE} and | |
4638 | @code{TARGET_ASM_FUNCTION_EPILOGUE} must treat leaf functions specially. | |
4639 | The C variable @code{current_function_is_leaf} is nonzero for such a | |
4640 | function. @xref{Leaf Functions}. | |
4641 | ||
4642 | On some machines, some functions pop their arguments on exit while | |
4643 | others leave that for the caller to do. For example, the 68020 when | |
4644 | given @option{-mrtd} pops arguments in functions that take a fixed | |
4645 | number of arguments. | |
4646 | ||
4647 | @findex current_function_pops_args | |
4648 | Your definition of the macro @code{RETURN_POPS_ARGS} decides which | |
4649 | functions pop their own arguments. @code{TARGET_ASM_FUNCTION_EPILOGUE} | |
4650 | needs to know what was decided. The variable that is called | |
4651 | @code{current_function_pops_args} is the number of bytes of its | |
4652 | arguments that a function should pop. @xref{Scalar Return}. | |
4653 | @c what is the "its arguments" in the above sentence referring to, pray | |
4654 | @c tell? --mew 5feb93 | |
4655 | @end deftypefn | |
4656 | ||
feca2ed3 JW |
4657 | @itemize @bullet |
4658 | @item | |
4659 | @findex current_function_pretend_args_size | |
4660 | A region of @code{current_function_pretend_args_size} bytes of | |
4661 | uninitialized space just underneath the first argument arriving on the | |
4662 | stack. (This may not be at the very start of the allocated stack region | |
4663 | if the calling sequence has pushed anything else since pushing the stack | |
4664 | arguments. But usually, on such machines, nothing else has been pushed | |
4665 | yet, because the function prologue itself does all the pushing.) This | |
4666 | region is used on machines where an argument may be passed partly in | |
4667 | registers and partly in memory, and, in some cases to support the | |
6c535c69 | 4668 | features in @code{<stdarg.h>}. |
feca2ed3 JW |
4669 | |
4670 | @item | |
4671 | An area of memory used to save certain registers used by the function. | |
4672 | The size of this area, which may also include space for such things as | |
4673 | the return address and pointers to previous stack frames, is | |
4674 | machine-specific and usually depends on which registers have been used | |
4675 | in the function. Machines with register windows often do not require | |
4676 | a save area. | |
4677 | ||
4678 | @item | |
4679 | A region of at least @var{size} bytes, possibly rounded up to an allocation | |
4680 | boundary, to contain the local variables of the function. On some machines, | |
4681 | this region and the save area may occur in the opposite order, with the | |
4682 | save area closer to the top of the stack. | |
4683 | ||
4684 | @item | |
4685 | @cindex @code{ACCUMULATE_OUTGOING_ARGS} and stack frames | |
4686 | Optionally, when @code{ACCUMULATE_OUTGOING_ARGS} is defined, a region of | |
4687 | @code{current_function_outgoing_args_size} bytes to be used for outgoing | |
4688 | argument lists of the function. @xref{Stack Arguments}. | |
4689 | @end itemize | |
4690 | ||
a2c4f8e0 | 4691 | @defmac EXIT_IGNORE_STACK |
feca2ed3 JW |
4692 | Define this macro as a C expression that is nonzero if the return |
4693 | instruction or the function epilogue ignores the value of the stack | |
4694 | pointer; in other words, if it is safe to delete an instruction to | |
9d05bbce KH |
4695 | adjust the stack pointer before a return from the function. The |
4696 | default is 0. | |
feca2ed3 JW |
4697 | |
4698 | Note that this macro's value is relevant only for functions for which | |
4699 | frame pointers are maintained. It is never safe to delete a final | |
4700 | stack adjustment in a function that has no frame pointer, and the | |
4701 | compiler knows this regardless of @code{EXIT_IGNORE_STACK}. | |
a2c4f8e0 | 4702 | @end defmac |
feca2ed3 | 4703 | |
a2c4f8e0 | 4704 | @defmac EPILOGUE_USES (@var{regno}) |
8760eaae | 4705 | Define this macro as a C expression that is nonzero for registers that are |
feca2ed3 | 4706 | used by the epilogue or the @samp{return} pattern. The stack and frame |
86c33cd0 | 4707 | pointer registers are already assumed to be used as needed. |
a2c4f8e0 | 4708 | @end defmac |
feca2ed3 | 4709 | |
a2c4f8e0 | 4710 | @defmac EH_USES (@var{regno}) |
15b5aef3 RH |
4711 | Define this macro as a C expression that is nonzero for registers that are |
4712 | used by the exception handling mechanism, and so should be considered live | |
4713 | on entry to an exception edge. | |
a2c4f8e0 | 4714 | @end defmac |
15b5aef3 | 4715 | |
a2c4f8e0 | 4716 | @defmac DELAY_SLOTS_FOR_EPILOGUE |
feca2ed3 JW |
4717 | Define this macro if the function epilogue contains delay slots to which |
4718 | instructions from the rest of the function can be ``moved''. The | |
4719 | definition should be a C expression whose value is an integer | |
4720 | representing the number of delay slots there. | |
a2c4f8e0 | 4721 | @end defmac |
feca2ed3 | 4722 | |
a2c4f8e0 | 4723 | @defmac ELIGIBLE_FOR_EPILOGUE_DELAY (@var{insn}, @var{n}) |
feca2ed3 JW |
4724 | A C expression that returns 1 if @var{insn} can be placed in delay |
4725 | slot number @var{n} of the epilogue. | |
4726 | ||
4727 | The argument @var{n} is an integer which identifies the delay slot now | |
4728 | being considered (since different slots may have different rules of | |
4729 | eligibility). It is never negative and is always less than the number | |
4730 | of epilogue delay slots (what @code{DELAY_SLOTS_FOR_EPILOGUE} returns). | |
4731 | If you reject a particular insn for a given delay slot, in principle, it | |
4732 | may be reconsidered for a subsequent delay slot. Also, other insns may | |
4733 | (at least in principle) be considered for the so far unfilled delay | |
4734 | slot. | |
4735 | ||
4736 | @findex current_function_epilogue_delay_list | |
4737 | @findex final_scan_insn | |
4738 | The insns accepted to fill the epilogue delay slots are put in an RTL | |
4739 | list made with @code{insn_list} objects, stored in the variable | |
4740 | @code{current_function_epilogue_delay_list}. The insn for the first | |
4741 | delay slot comes first in the list. Your definition of the macro | |
08c148a8 NB |
4742 | @code{TARGET_ASM_FUNCTION_EPILOGUE} should fill the delay slots by |
4743 | outputting the insns in this list, usually by calling | |
4744 | @code{final_scan_insn}. | |
feca2ed3 JW |
4745 | |
4746 | You need not define this macro if you did not define | |
4747 | @code{DELAY_SLOTS_FOR_EPILOGUE}. | |
a2c4f8e0 | 4748 | @end defmac |
feca2ed3 | 4749 | |
65e71cd6 | 4750 | @deftypefn {Target Hook} void TARGET_ASM_OUTPUT_MI_THUNK (FILE *@var{file}, tree @var{thunk_fndecl}, HOST_WIDE_INT @var{delta}, HOST_WIDE_INT @var{vcall_offset}, tree @var{function}) |
483ab821 | 4751 | A function that outputs the assembler code for a thunk |
feca2ed3 JW |
4752 | function, used to implement C++ virtual function calls with multiple |
4753 | inheritance. The thunk acts as a wrapper around a virtual function, | |
4754 | adjusting the implicit object parameter before handing control off to | |
4755 | the real function. | |
4756 | ||
4757 | First, emit code to add the integer @var{delta} to the location that | |
4758 | contains the incoming first argument. Assume that this argument | |
4759 | contains a pointer, and is the one used to pass the @code{this} pointer | |
4760 | in C++. This is the incoming argument @emph{before} the function prologue, | |
e979f9e8 | 4761 | e.g.@: @samp{%o0} on a sparc. The addition must preserve the values of |
feca2ed3 JW |
4762 | all other incoming arguments. |
4763 | ||
65e71cd6 EB |
4764 | Then, if @var{vcall_offset} is nonzero, an additional adjustment should be |
4765 | made after adding @code{delta}. In particular, if @var{p} is the | |
4766 | adjusted pointer, the following adjustment should be made: | |
4767 | ||
4768 | @smallexample | |
4769 | p += (*((ptrdiff_t **)p))[vcall_offset/sizeof(ptrdiff_t)] | |
4770 | @end smallexample | |
4771 | ||
4772 | After the additions, emit code to jump to @var{function}, which is a | |
feca2ed3 JW |
4773 | @code{FUNCTION_DECL}. This is a direct pure jump, not a call, and does |
4774 | not touch the return address. Hence returning from @var{FUNCTION} will | |
4775 | return to whoever called the current @samp{thunk}. | |
4776 | ||
4777 | The effect must be as if @var{function} had been called directly with | |
4778 | the adjusted first argument. This macro is responsible for emitting all | |
08c148a8 NB |
4779 | of the code for a thunk function; @code{TARGET_ASM_FUNCTION_PROLOGUE} |
4780 | and @code{TARGET_ASM_FUNCTION_EPILOGUE} are not invoked. | |
feca2ed3 JW |
4781 | |
4782 | The @var{thunk_fndecl} is redundant. (@var{delta} and @var{function} | |
4783 | have already been extracted from it.) It might possibly be useful on | |
4784 | some targets, but probably not. | |
4785 | ||
861bb6c1 | 4786 | If you do not define this macro, the target-independent code in the C++ |
c771326b | 4787 | front end will generate a less efficient heavyweight thunk that calls |
861bb6c1 JL |
4788 | @var{function} instead of jumping to it. The generic approach does |
4789 | not support varargs. | |
483ab821 MM |
4790 | @end deftypefn |
4791 | ||
65e71cd6 EB |
4792 | @deftypefn {Target Hook} bool TARGET_ASM_CAN_OUTPUT_MI_THUNK (tree @var{thunk_fndecl}, HOST_WIDE_INT @var{delta}, HOST_WIDE_INT @var{vcall_offset}, tree @var{function}) |
4793 | A function that returns true if TARGET_ASM_OUTPUT_MI_THUNK would be able | |
4794 | to output the assembler code for the thunk function specified by the | |
4795 | arguments it is passed, and false otherwise. In the latter case, the | |
4796 | generic approach will be used by the C++ front end, with the limitations | |
4797 | previously exposed. | |
483ab821 | 4798 | @end deftypefn |
feca2ed3 JW |
4799 | |
4800 | @node Profiling | |
4801 | @subsection Generating Code for Profiling | |
4802 | @cindex profiling, code generation | |
4803 | ||
4804 | These macros will help you generate code for profiling. | |
4805 | ||
a2c4f8e0 | 4806 | @defmac FUNCTION_PROFILER (@var{file}, @var{labelno}) |
feca2ed3 JW |
4807 | A C statement or compound statement to output to @var{file} some |
4808 | assembler code to call the profiling subroutine @code{mcount}. | |
feca2ed3 JW |
4809 | |
4810 | @findex mcount | |
980e2067 | 4811 | The details of how @code{mcount} expects to be called are determined by |
161d7b59 | 4812 | your operating system environment, not by GCC@. To figure them out, |
980e2067 JL |
4813 | compile a small program for profiling using the system's installed C |
4814 | compiler and look at the assembler code that results. | |
4815 | ||
4816 | Older implementations of @code{mcount} expect the address of a counter | |
4817 | variable to be loaded into some register. The name of this variable is | |
4818 | @samp{LP} followed by the number @var{labelno}, so you would generate | |
4819 | the name using @samp{LP%d} in a @code{fprintf}. | |
a2c4f8e0 | 4820 | @end defmac |
980e2067 | 4821 | |
a2c4f8e0 | 4822 | @defmac PROFILE_HOOK |
411707f4 CC |
4823 | A C statement or compound statement to output to @var{file} some assembly |
4824 | code to call the profiling subroutine @code{mcount} even the target does | |
4825 | not support profiling. | |
a2c4f8e0 | 4826 | @end defmac |
411707f4 | 4827 | |
a2c4f8e0 | 4828 | @defmac NO_PROFILE_COUNTERS |
8b65a354 JZ |
4829 | Define this macro to be an expression with a nonzero value if the |
4830 | @code{mcount} subroutine on your system does not need a counter variable | |
4831 | allocated for each function. This is true for almost all modern | |
4832 | implementations. If you define this macro, you must not use the | |
4833 | @var{labelno} argument to @code{FUNCTION_PROFILER}. | |
a2c4f8e0 | 4834 | @end defmac |
feca2ed3 | 4835 | |
a2c4f8e0 | 4836 | @defmac PROFILE_BEFORE_PROLOGUE |
feca2ed3 JW |
4837 | Define this macro if the code for function profiling should come before |
4838 | the function prologue. Normally, the profiling code comes after. | |
a2c4f8e0 | 4839 | @end defmac |
feca2ed3 | 4840 | |
91d231cb JM |
4841 | @node Tail Calls |
4842 | @subsection Permitting tail calls | |
4843 | @cindex tail calls | |
b36f4ed3 | 4844 | |
4977bab6 ZW |
4845 | @deftypefn {Target Hook} bool TARGET_FUNCTION_OK_FOR_SIBCALL (tree @var{decl}, tree @var{exp}) |
4846 | True if it is ok to do sibling call optimization for the specified | |
4847 | call expression @var{exp}. @var{decl} will be the called function, | |
4848 | or @code{NULL} if this is an indirect call. | |
4cb1433c RH |
4849 | |
4850 | It is not uncommon for limitations of calling conventions to prevent | |
4851 | tail calls to functions outside the current unit of translation, or | |
4977bab6 | 4852 | during PIC compilation. The hook is used to enforce these restrictions, |
02f52e19 | 4853 | as the @code{sibcall} md pattern can not fail, or fall over to a |
4977bab6 ZW |
4854 | ``normal'' call. The criteria for successful sibling call optimization |
4855 | may vary greatly between different architectures. | |
4856 | @end deftypefn | |
4cb1433c | 4857 | |
912f2dac DB |
4858 | @deftypefn {Target Hook} void TARGET_EXTRA_LIVE_ON_ENTRY (bitmap *@var{regs}) |
4859 | Add any hard registers to @var{regs} that are live on entry to the | |
4860 | function. This hook only needs to be defined to provide registers that | |
4861 | cannot be found by examination of FUNCTION_ARG_REGNO_P, the callee saved | |
4862 | registers, STATIC_CHAIN_INCOMING_REGNUM, STATIC_CHAIN_REGNUM, | |
4863 | TARGET_STRUCT_VALUE_RTX, FRAME_POINTER_REGNUM, EH_USES, | |
4864 | FRAME_POINTER_REGNUM, ARG_POINTER_REGNUM, and the PIC_OFFSET_TABLE_REGNUM. | |
4865 | @end deftypefn | |
4866 | ||
7d69de61 RH |
4867 | @node Stack Smashing Protection |
4868 | @subsection Stack smashing protection | |
4869 | @cindex stack smashing protection | |
4870 | ||
4871 | @deftypefn {Target Hook} tree TARGET_STACK_PROTECT_GUARD (void) | |
4872 | This hook returns a @code{DECL} node for the external variable to use | |
083cad55 | 4873 | for the stack protection guard. This variable is initialized by the |
7d69de61 RH |
4874 | runtime to some random value and is used to initialize the guard value |
4875 | that is placed at the top of the local stack frame. The type of this | |
4876 | variable must be @code{ptr_type_node}. | |
4877 | ||
4878 | The default version of this hook creates a variable called | |
4879 | @samp{__stack_chk_guard}, which is normally defined in @file{libgcc2.c}. | |
4880 | @end deftypefn | |
4881 | ||
4882 | @deftypefn {Target Hook} tree TARGET_STACK_PROTECT_FAIL (void) | |
4883 | This hook returns a tree expression that alerts the runtime that the | |
4884 | stack protect guard variable has been modified. This expression should | |
4885 | involve a call to a @code{noreturn} function. | |
4886 | ||
4887 | The default version of this hook invokes a function called | |
083cad55 | 4888 | @samp{__stack_chk_fail}, taking no arguments. This function is |
7d69de61 RH |
4889 | normally defined in @file{libgcc2.c}. |
4890 | @end deftypefn | |
4891 | ||
feca2ed3 JW |
4892 | @node Varargs |
4893 | @section Implementing the Varargs Macros | |
4894 | @cindex varargs implementation | |
4895 | ||
aee96fe9 JM |
4896 | GCC comes with an implementation of @code{<varargs.h>} and |
4897 | @code{<stdarg.h>} that work without change on machines that pass arguments | |
feca2ed3 JW |
4898 | on the stack. Other machines require their own implementations of |
4899 | varargs, and the two machine independent header files must have | |
4900 | conditionals to include it. | |
4901 | ||
aee96fe9 | 4902 | ISO @code{<stdarg.h>} differs from traditional @code{<varargs.h>} mainly in |
feca2ed3 JW |
4903 | the calling convention for @code{va_start}. The traditional |
4904 | implementation takes just one argument, which is the variable in which | |
5490d604 | 4905 | to store the argument pointer. The ISO implementation of |
feca2ed3 JW |
4906 | @code{va_start} takes an additional second argument. The user is |
4907 | supposed to write the last named argument of the function here. | |
4908 | ||
4909 | However, @code{va_start} should not use this argument. The way to find | |
4910 | the end of the named arguments is with the built-in functions described | |
4911 | below. | |
4912 | ||
a2c4f8e0 | 4913 | @defmac __builtin_saveregs () |
feca2ed3 | 4914 | Use this built-in function to save the argument registers in memory so |
5490d604 | 4915 | that the varargs mechanism can access them. Both ISO and traditional |
feca2ed3 | 4916 | versions of @code{va_start} must use @code{__builtin_saveregs}, unless |
c2379679 | 4917 | you use @code{TARGET_SETUP_INCOMING_VARARGS} (see below) instead. |
feca2ed3 JW |
4918 | |
4919 | On some machines, @code{__builtin_saveregs} is open-coded under the | |
f61c92c3 KH |
4920 | control of the target hook @code{TARGET_EXPAND_BUILTIN_SAVEREGS}. On |
4921 | other machines, it calls a routine written in assembler language, | |
4922 | found in @file{libgcc2.c}. | |
feca2ed3 JW |
4923 | |
4924 | Code generated for the call to @code{__builtin_saveregs} appears at the | |
4925 | beginning of the function, as opposed to where the call to | |
4926 | @code{__builtin_saveregs} is written, regardless of what the code is. | |
4927 | This is because the registers must be saved before the function starts | |
4928 | to use them for its own purposes. | |
4929 | @c i rewrote the first sentence above to fix an overfull hbox. --mew | |
4930 | @c 10feb93 | |
a2c4f8e0 | 4931 | @end defmac |
feca2ed3 | 4932 | |
a2c4f8e0 | 4933 | @defmac __builtin_args_info (@var{category}) |
feca2ed3 JW |
4934 | Use this built-in function to find the first anonymous arguments in |
4935 | registers. | |
4936 | ||
4937 | In general, a machine may have several categories of registers used for | |
4938 | arguments, each for a particular category of data types. (For example, | |
4939 | on some machines, floating-point registers are used for floating-point | |
4940 | arguments while other arguments are passed in the general registers.) | |
4941 | To make non-varargs functions use the proper calling convention, you | |
4942 | have defined the @code{CUMULATIVE_ARGS} data type to record how many | |
4943 | registers in each category have been used so far | |
4944 | ||
4945 | @code{__builtin_args_info} accesses the same data structure of type | |
4946 | @code{CUMULATIVE_ARGS} after the ordinary argument layout is finished | |
4947 | with it, with @var{category} specifying which word to access. Thus, the | |
4948 | value indicates the first unused register in a given category. | |
4949 | ||
4950 | Normally, you would use @code{__builtin_args_info} in the implementation | |
4951 | of @code{va_start}, accessing each category just once and storing the | |
4952 | value in the @code{va_list} object. This is because @code{va_list} will | |
4953 | have to update the values, and there is no way to alter the | |
4954 | values accessed by @code{__builtin_args_info}. | |
a2c4f8e0 | 4955 | @end defmac |
feca2ed3 | 4956 | |
a2c4f8e0 | 4957 | @defmac __builtin_next_arg (@var{lastarg}) |
feca2ed3 JW |
4958 | This is the equivalent of @code{__builtin_args_info}, for stack |
4959 | arguments. It returns the address of the first anonymous stack | |
767094dd | 4960 | argument, as type @code{void *}. If @code{ARGS_GROW_DOWNWARD}, it |
feca2ed3 JW |
4961 | returns the address of the location above the first anonymous stack |
4962 | argument. Use it in @code{va_start} to initialize the pointer for | |
4963 | fetching arguments from the stack. Also use it in @code{va_start} to | |
4964 | verify that the second parameter @var{lastarg} is the last named argument | |
4965 | of the current function. | |
a2c4f8e0 | 4966 | @end defmac |
feca2ed3 | 4967 | |
a2c4f8e0 | 4968 | @defmac __builtin_classify_type (@var{object}) |
feca2ed3 JW |
4969 | Since each machine has its own conventions for which data types are |
4970 | passed in which kind of register, your implementation of @code{va_arg} | |
4971 | has to embody these conventions. The easiest way to categorize the | |
4972 | specified data type is to use @code{__builtin_classify_type} together | |
4973 | with @code{sizeof} and @code{__alignof__}. | |
4974 | ||
4975 | @code{__builtin_classify_type} ignores the value of @var{object}, | |
4976 | considering only its data type. It returns an integer describing what | |
4977 | kind of type that is---integer, floating, pointer, structure, and so on. | |
4978 | ||
4979 | The file @file{typeclass.h} defines an enumeration that you can use to | |
4980 | interpret the values of @code{__builtin_classify_type}. | |
a2c4f8e0 | 4981 | @end defmac |
feca2ed3 JW |
4982 | |
4983 | These machine description macros help implement varargs: | |
4984 | ||
61f71b34 DD |
4985 | @deftypefn {Target Hook} rtx TARGET_EXPAND_BUILTIN_SAVEREGS (void) |
4986 | If defined, this hook produces the machine-specific code for a call to | |
4987 | @code{__builtin_saveregs}. This code will be moved to the very | |
4988 | beginning of the function, before any parameter access are made. The | |
4989 | return value of this function should be an RTX that contains the value | |
4990 | to use as the return of @code{__builtin_saveregs}. | |
4991 | @end deftypefn | |
feca2ed3 | 4992 | |
61f71b34 DD |
4993 | @deftypefn {Target Hook} void TARGET_SETUP_INCOMING_VARARGS (CUMULATIVE_ARGS *@var{args_so_far}, enum machine_mode @var{mode}, tree @var{type}, int *@var{pretend_args_size}, int @var{second_time}) |
4994 | This target hook offers an alternative to using | |
4995 | @code{__builtin_saveregs} and defining the hook | |
4996 | @code{TARGET_EXPAND_BUILTIN_SAVEREGS}. Use it to store the anonymous | |
4997 | register arguments into the stack so that all the arguments appear to | |
4998 | have been passed consecutively on the stack. Once this is done, you can | |
4999 | use the standard implementation of varargs that works for machines that | |
5000 | pass all their arguments on the stack. | |
feca2ed3 | 5001 | |
61f71b34 | 5002 | The argument @var{args_so_far} points to the @code{CUMULATIVE_ARGS} data |
8760eaae | 5003 | structure, containing the values that are obtained after processing the |
feca2ed3 JW |
5004 | named arguments. The arguments @var{mode} and @var{type} describe the |
5005 | last named argument---its machine mode and its data type as a tree node. | |
5006 | ||
61f71b34 DD |
5007 | The target hook should do two things: first, push onto the stack all the |
5008 | argument registers @emph{not} used for the named arguments, and second, | |
5009 | store the size of the data thus pushed into the @code{int}-valued | |
5010 | variable pointed to by @var{pretend_args_size}. The value that you | |
5011 | store here will serve as additional offset for setting up the stack | |
5012 | frame. | |
feca2ed3 JW |
5013 | |
5014 | Because you must generate code to push the anonymous arguments at | |
5015 | compile time without knowing their data types, | |
61f71b34 DD |
5016 | @code{TARGET_SETUP_INCOMING_VARARGS} is only useful on machines that |
5017 | have just a single category of argument register and use it uniformly | |
5018 | for all data types. | |
feca2ed3 JW |
5019 | |
5020 | If the argument @var{second_time} is nonzero, it means that the | |
5021 | arguments of the function are being analyzed for the second time. This | |
5022 | happens for an inline function, which is not actually compiled until the | |
61f71b34 | 5023 | end of the source file. The hook @code{TARGET_SETUP_INCOMING_VARARGS} should |
feca2ed3 | 5024 | not generate any instructions in this case. |
61f71b34 | 5025 | @end deftypefn |
feca2ed3 | 5026 | |
61f71b34 DD |
5027 | @deftypefn {Target Hook} bool TARGET_STRICT_ARGUMENT_NAMING (CUMULATIVE_ARGS *@var{ca}) |
5028 | Define this hook to return @code{true} if the location where a function | |
e5e809f4 | 5029 | argument is passed depends on whether or not it is a named argument. |
feca2ed3 | 5030 | |
61f71b34 DD |
5031 | This hook controls how the @var{named} argument to @code{FUNCTION_ARG} |
5032 | is set for varargs and stdarg functions. If this hook returns | |
5033 | @code{true}, the @var{named} argument is always true for named | |
5034 | arguments, and false for unnamed arguments. If it returns @code{false}, | |
5b4ef0b1 | 5035 | but @code{TARGET_PRETEND_OUTGOING_VARARGS_NAMED} returns @code{true}, |
61f71b34 DD |
5036 | then all arguments are treated as named. Otherwise, all named arguments |
5037 | except the last are treated as named. | |
e5e809f4 | 5038 | |
61f71b34 DD |
5039 | You need not define this hook if it always returns zero. |
5040 | @end deftypefn | |
9ab70a9b | 5041 | |
61f71b34 | 5042 | @deftypefn {Target Hook} bool TARGET_PRETEND_OUTGOING_VARARGS_NAMED |
9ab70a9b | 5043 | If you need to conditionally change ABIs so that one works with |
61f71b34 DD |
5044 | @code{TARGET_SETUP_INCOMING_VARARGS}, but the other works like neither |
5045 | @code{TARGET_SETUP_INCOMING_VARARGS} nor @code{TARGET_STRICT_ARGUMENT_NAMING} was | |
5046 | defined, then define this hook to return @code{true} if | |
c2379679 | 5047 | @code{TARGET_SETUP_INCOMING_VARARGS} is used, @code{false} otherwise. |
61f71b34 DD |
5048 | Otherwise, you should not define this hook. |
5049 | @end deftypefn | |
feca2ed3 JW |
5050 | |
5051 | @node Trampolines | |
5052 | @section Trampolines for Nested Functions | |
5053 | @cindex trampolines for nested functions | |
5054 | @cindex nested functions, trampolines for | |
5055 | ||
5056 | A @dfn{trampoline} is a small piece of code that is created at run time | |
5057 | when the address of a nested function is taken. It normally resides on | |
5058 | the stack, in the stack frame of the containing function. These macros | |
a3a15b4d | 5059 | tell GCC how to generate code to allocate and initialize a |
feca2ed3 JW |
5060 | trampoline. |
5061 | ||
5062 | The instructions in the trampoline must do two things: load a constant | |
5063 | address into the static chain register, and jump to the real address of | |
5064 | the nested function. On CISC machines such as the m68k, this requires | |
5065 | two instructions, a move immediate and a jump. Then the two addresses | |
5066 | exist in the trampoline as word-long immediate operands. On RISC | |
5067 | machines, it is often necessary to load each address into a register in | |
5068 | two parts. Then pieces of each address form separate immediate | |
5069 | operands. | |
5070 | ||
5071 | The code generated to initialize the trampoline must store the variable | |
5072 | parts---the static chain value and the function address---into the | |
5073 | immediate operands of the instructions. On a CISC machine, this is | |
5074 | simply a matter of copying each address to a memory reference at the | |
5075 | proper offset from the start of the trampoline. On a RISC machine, it | |
5076 | may be necessary to take out pieces of the address and store them | |
5077 | separately. | |
5078 | ||
a2c4f8e0 | 5079 | @defmac TRAMPOLINE_TEMPLATE (@var{file}) |
feca2ed3 JW |
5080 | A C statement to output, on the stream @var{file}, assembler code for a |
5081 | block of data that contains the constant parts of a trampoline. This | |
5082 | code should not include a label---the label is taken care of | |
5083 | automatically. | |
5084 | ||
5085 | If you do not define this macro, it means no template is needed | |
5086 | for the target. Do not define this macro on systems where the block move | |
5087 | code to copy the trampoline into place would be larger than the code | |
5088 | to generate it on the spot. | |
a2c4f8e0 | 5089 | @end defmac |
feca2ed3 | 5090 | |
a2c4f8e0 | 5091 | @defmac TRAMPOLINE_SECTION |
d6b5193b RS |
5092 | Return the section into which the trampoline template is to be placed |
5093 | (@pxref{Sections}). The default value is @code{readonly_data_section}. | |
a2c4f8e0 | 5094 | @end defmac |
feca2ed3 | 5095 | |
a2c4f8e0 | 5096 | @defmac TRAMPOLINE_SIZE |
feca2ed3 | 5097 | A C expression for the size in bytes of the trampoline, as an integer. |
a2c4f8e0 | 5098 | @end defmac |
feca2ed3 | 5099 | |
a2c4f8e0 | 5100 | @defmac TRAMPOLINE_ALIGNMENT |
feca2ed3 JW |
5101 | Alignment required for trampolines, in bits. |
5102 | ||
5103 | If you don't define this macro, the value of @code{BIGGEST_ALIGNMENT} | |
5104 | is used for aligning trampolines. | |
a2c4f8e0 | 5105 | @end defmac |
feca2ed3 | 5106 | |
a2c4f8e0 | 5107 | @defmac INITIALIZE_TRAMPOLINE (@var{addr}, @var{fnaddr}, @var{static_chain}) |
feca2ed3 JW |
5108 | A C statement to initialize the variable parts of a trampoline. |
5109 | @var{addr} is an RTX for the address of the trampoline; @var{fnaddr} is | |
5110 | an RTX for the address of the nested function; @var{static_chain} is an | |
5111 | RTX for the static chain value that should be passed to the function | |
5112 | when it is called. | |
a2c4f8e0 | 5113 | @end defmac |
feca2ed3 | 5114 | |
a2c4f8e0 | 5115 | @defmac TRAMPOLINE_ADJUST_ADDRESS (@var{addr}) |
b33493e3 AO |
5116 | A C statement that should perform any machine-specific adjustment in |
5117 | the address of the trampoline. Its argument contains the address that | |
5118 | was passed to @code{INITIALIZE_TRAMPOLINE}. In case the address to be | |
5119 | used for a function call should be different from the address in which | |
5120 | the template was stored, the different address should be assigned to | |
5121 | @var{addr}. If this macro is not defined, @var{addr} will be used for | |
5122 | function calls. | |
5123 | ||
08c148a8 NB |
5124 | @cindex @code{TARGET_ASM_FUNCTION_EPILOGUE} and trampolines |
5125 | @cindex @code{TARGET_ASM_FUNCTION_PROLOGUE} and trampolines | |
feca2ed3 JW |
5126 | If this macro is not defined, by default the trampoline is allocated as |
5127 | a stack slot. This default is right for most machines. The exceptions | |
5128 | are machines where it is impossible to execute instructions in the stack | |
5129 | area. On such machines, you may have to implement a separate stack, | |
08c148a8 NB |
5130 | using this macro in conjunction with @code{TARGET_ASM_FUNCTION_PROLOGUE} |
5131 | and @code{TARGET_ASM_FUNCTION_EPILOGUE}. | |
feca2ed3 JW |
5132 | |
5133 | @var{fp} points to a data structure, a @code{struct function}, which | |
5134 | describes the compilation status of the immediate containing function of | |
0d569849 | 5135 | the function which the trampoline is for. The stack slot for the |
feca2ed3 JW |
5136 | trampoline is in the stack frame of this containing function. Other |
5137 | allocation strategies probably must do something analogous with this | |
5138 | information. | |
a2c4f8e0 | 5139 | @end defmac |
feca2ed3 JW |
5140 | |
5141 | Implementing trampolines is difficult on many machines because they have | |
5142 | separate instruction and data caches. Writing into a stack location | |
5143 | fails to clear the memory in the instruction cache, so when the program | |
5144 | jumps to that location, it executes the old contents. | |
5145 | ||
5146 | Here are two possible solutions. One is to clear the relevant parts of | |
5147 | the instruction cache whenever a trampoline is set up. The other is to | |
5148 | make all trampolines identical, by having them jump to a standard | |
5149 | subroutine. The former technique makes trampoline execution faster; the | |
5150 | latter makes initialization faster. | |
5151 | ||
5152 | To clear the instruction cache when a trampoline is initialized, define | |
f691dc3b | 5153 | the following macro. |
feca2ed3 | 5154 | |
a2c4f8e0 | 5155 | @defmac CLEAR_INSN_CACHE (@var{beg}, @var{end}) |
feca2ed3 | 5156 | If defined, expands to a C expression clearing the @emph{instruction |
f691dc3b AJ |
5157 | cache} in the specified interval. The definition of this macro would |
5158 | typically be a series of @code{asm} statements. Both @var{beg} and | |
5159 | @var{end} are both pointer expressions. | |
a2c4f8e0 | 5160 | @end defmac |
feca2ed3 | 5161 | |
e7a742ec EB |
5162 | The operating system may also require the stack to be made executable |
5163 | before calling the trampoline. To implement this requirement, define | |
5164 | the following macro. | |
5165 | ||
5166 | @defmac ENABLE_EXECUTE_STACK | |
5167 | Define this macro if certain operations must be performed before executing | |
5168 | code located on the stack. The macro should expand to a series of C | |
431ae0bf | 5169 | file-scope constructs (e.g.@: functions) and provide a unique entry point |
e7a742ec EB |
5170 | named @code{__enable_execute_stack}. The target is responsible for |
5171 | emitting calls to the entry point in the code, for example from the | |
5172 | @code{INITIALIZE_TRAMPOLINE} macro. | |
5173 | @end defmac | |
5174 | ||
feca2ed3 JW |
5175 | To use a standard subroutine, define the following macro. In addition, |
5176 | you must make sure that the instructions in a trampoline fill an entire | |
5177 | cache line with identical instructions, or else ensure that the | |
5178 | beginning of the trampoline code is always aligned at the same point in | |
5179 | its cache line. Look in @file{m68k.h} as a guide. | |
5180 | ||
a2c4f8e0 | 5181 | @defmac TRANSFER_FROM_TRAMPOLINE |
feca2ed3 JW |
5182 | Define this macro if trampolines need a special subroutine to do their |
5183 | work. The macro should expand to a series of @code{asm} statements | |
161d7b59 | 5184 | which will be compiled with GCC@. They go in a library function named |
feca2ed3 JW |
5185 | @code{__transfer_from_trampoline}. |
5186 | ||
5187 | If you need to avoid executing the ordinary prologue code of a compiled | |
5188 | C function when you jump to the subroutine, you can do so by placing a | |
5189 | special label of your own in the assembler code. Use one @code{asm} | |
5190 | statement to generate an assembler label, and another to make the label | |
5191 | global. Then trampolines can use that label to jump directly to your | |
5192 | special assembler code. | |
a2c4f8e0 | 5193 | @end defmac |
feca2ed3 JW |
5194 | |
5195 | @node Library Calls | |
5196 | @section Implicit Calls to Library Routines | |
5197 | @cindex library subroutine names | |
5198 | @cindex @file{libgcc.a} | |
5199 | ||
5200 | @c prevent bad page break with this line | |
5201 | Here is an explanation of implicit calls to library routines. | |
5202 | ||
a2c4f8e0 | 5203 | @defmac DECLARE_LIBRARY_RENAMES |
d8088c6f BS |
5204 | This macro, if defined, should expand to a piece of C code that will get |
5205 | expanded when compiling functions for libgcc.a. It can be used to | |
2dd76960 | 5206 | provide alternate names for GCC's internal library functions if there |
d8088c6f | 5207 | are ABI-mandated names that the compiler should provide. |
a2c4f8e0 | 5208 | @end defmac |
d8088c6f | 5209 | |
c15c90bb ZW |
5210 | @findex init_one_libfunc |
5211 | @findex set_optab_libfunc | |
5212 | @deftypefn {Target Hook} void TARGET_INIT_LIBFUNCS (void) | |
5213 | This hook should declare additional library routines or rename | |
5214 | existing ones, using the functions @code{set_optab_libfunc} and | |
5215 | @code{init_one_libfunc} defined in @file{optabs.c}. | |
5216 | @code{init_optabs} calls this macro after initializing all the normal | |
5217 | library routines. | |
feca2ed3 | 5218 | |
c15c90bb ZW |
5219 | The default is to do nothing. Most ports don't need to define this hook. |
5220 | @end deftypefn | |
c5c60e15 | 5221 | |
9c917669 | 5222 | @defmac FLOAT_LIB_COMPARE_RETURNS_BOOL (@var{mode}, @var{comparison}) |
c15c90bb ZW |
5223 | This macro should return @code{true} if the library routine that |
5224 | implements the floating point comparison operator @var{comparison} in | |
5225 | mode @var{mode} will return a boolean, and @var{false} if it will | |
5226 | return a tristate. | |
5227 | ||
5228 | GCC's own floating point libraries return tristates from the | |
5229 | comparison operators, so the default returns false always. Most ports | |
5230 | don't need to define this macro. | |
5231 | @end defmac | |
5232 | ||
b3f8d95d MM |
5233 | @defmac TARGET_LIB_INT_CMP_BIASED |
5234 | This macro should evaluate to @code{true} if the integer comparison | |
5235 | functions (like @code{__cmpdi2}) return 0 to indicate that the first | |
5236 | operand is smaller than the second, 1 to indicate that they are equal, | |
5237 | and 2 to indicate that the first operand is greater than the second. | |
38b974a6 | 5238 | If this macro evaluates to @code{false} the comparison functions return |
78466c0e | 5239 | @minus{}1, 0, and 1 instead of 0, 1, and 2. If the target uses the routines |
b3f8d95d MM |
5240 | in @file{libgcc.a}, you do not need to define this macro. |
5241 | @end defmac | |
5242 | ||
c15c90bb ZW |
5243 | @cindex US Software GOFAST, floating point emulation library |
5244 | @cindex floating point emulation library, US Software GOFAST | |
5245 | @cindex GOFAST, floating point emulation library | |
5246 | @findex gofast_maybe_init_libfuncs | |
5247 | @defmac US_SOFTWARE_GOFAST | |
5248 | Define this macro if your system C library uses the US Software GOFAST | |
73774972 | 5249 | library to provide floating point emulation. |
c15c90bb ZW |
5250 | |
5251 | In addition to defining this macro, your architecture must set | |
5252 | @code{TARGET_INIT_LIBFUNCS} to @code{gofast_maybe_init_libfuncs}, or | |
5253 | else call that function from its version of that hook. It is defined | |
5254 | in @file{config/gofast.h}, which must be included by your | |
5255 | architecture's @file{@var{cpu}.c} file. See @file{sparc/sparc.c} for | |
5256 | an example. | |
5257 | ||
5258 | If this macro is defined, the | |
5259 | @code{TARGET_FLOAT_LIB_COMPARE_RETURNS_BOOL} target hook must return | |
5260 | false for @code{SFmode} and @code{DFmode} comparisons. | |
a2c4f8e0 | 5261 | @end defmac |
c5c60e15 | 5262 | |
feca2ed3 | 5263 | @cindex @code{EDOM}, implicit usage |
a2c4f8e0 ZW |
5264 | @findex matherr |
5265 | @defmac TARGET_EDOM | |
feca2ed3 | 5266 | The value of @code{EDOM} on the target machine, as a C integer constant |
a3a15b4d | 5267 | expression. If you don't define this macro, GCC does not attempt to |
feca2ed3 JW |
5268 | deposit the value of @code{EDOM} into @code{errno} directly. Look in |
5269 | @file{/usr/include/errno.h} to find the value of @code{EDOM} on your | |
5270 | system. | |
5271 | ||
5272 | If you do not define @code{TARGET_EDOM}, then compiled code reports | |
5273 | domain errors by calling the library function and letting it report the | |
5274 | error. If mathematical functions on your system use @code{matherr} when | |
5275 | there is an error, then you should leave @code{TARGET_EDOM} undefined so | |
5276 | that @code{matherr} is used normally. | |
a2c4f8e0 | 5277 | @end defmac |
feca2ed3 | 5278 | |
feca2ed3 | 5279 | @cindex @code{errno}, implicit usage |
a2c4f8e0 | 5280 | @defmac GEN_ERRNO_RTX |
feca2ed3 JW |
5281 | Define this macro as a C expression to create an rtl expression that |
5282 | refers to the global ``variable'' @code{errno}. (On certain systems, | |
5283 | @code{errno} may not actually be a variable.) If you don't define this | |
5284 | macro, a reasonable default is used. | |
a2c4f8e0 | 5285 | @end defmac |
feca2ed3 | 5286 | |
272f51a3 | 5287 | @cindex C99 math functions, implicit usage |
a2c4f8e0 | 5288 | @defmac TARGET_C99_FUNCTIONS |
272f51a3 | 5289 | When this macro is nonzero, GCC will implicitly optimize @code{sin} calls into |
3bcf1b13 | 5290 | @code{sinf} and similarly for other functions defined by C99 standard. The |
5472de36 SE |
5291 | default is zero because a number of existing systems lack support for these |
5292 | functions in their runtime so this macro needs to be redefined to one on | |
5293 | systems that do support the C99 runtime. | |
a2c4f8e0 | 5294 | @end defmac |
272f51a3 | 5295 | |
006339cd RG |
5296 | @cindex sincos math function, implicit usage |
5297 | @defmac TARGET_HAS_SINCOS | |
5298 | When this macro is nonzero, GCC will implicitly optimize calls to @code{sin} | |
5299 | and @code{cos} with the same argument to a call to @code{sincos}. The | |
5300 | default is zero. The target has to provide the following functions: | |
5301 | @smallexample | |
5302 | void sincos(double x, double *sin, double *cos); | |
5303 | void sincosf(float x, float *sin, float *cos); | |
5304 | void sincosl(long double x, long double *sin, long double *cos); | |
5305 | @end smallexample | |
5306 | @end defmac | |
5307 | ||
a2c4f8e0 | 5308 | @defmac NEXT_OBJC_RUNTIME |
2147b154 | 5309 | Define this macro to generate code for Objective-C message sending using |
feca2ed3 JW |
5310 | the calling convention of the NeXT system. This calling convention |
5311 | involves passing the object, the selector and the method arguments all | |
5312 | at once to the method-lookup library function. | |
5313 | ||
5314 | The default calling convention passes just the object and the selector | |
5315 | to the lookup function, which returns a pointer to the method. | |
a2c4f8e0 | 5316 | @end defmac |
feca2ed3 JW |
5317 | |
5318 | @node Addressing Modes | |
5319 | @section Addressing Modes | |
5320 | @cindex addressing modes | |
5321 | ||
5322 | @c prevent bad page break with this line | |
5323 | This is about addressing modes. | |
5324 | ||
a2c4f8e0 ZW |
5325 | @defmac HAVE_PRE_INCREMENT |
5326 | @defmacx HAVE_PRE_DECREMENT | |
5327 | @defmacx HAVE_POST_INCREMENT | |
5328 | @defmacx HAVE_POST_DECREMENT | |
df2a54e9 | 5329 | A C expression that is nonzero if the machine supports pre-increment, |
7a6bd5ae | 5330 | pre-decrement, post-increment, or post-decrement addressing respectively. |
a2c4f8e0 | 5331 | @end defmac |
feca2ed3 | 5332 | |
a2c4f8e0 ZW |
5333 | @defmac HAVE_PRE_MODIFY_DISP |
5334 | @defmacx HAVE_POST_MODIFY_DISP | |
df2a54e9 | 5335 | A C expression that is nonzero if the machine supports pre- or |
7a6bd5ae JL |
5336 | post-address side-effect generation involving constants other than |
5337 | the size of the memory operand. | |
a2c4f8e0 | 5338 | @end defmac |
864bcaa7 | 5339 | |
a2c4f8e0 ZW |
5340 | @defmac HAVE_PRE_MODIFY_REG |
5341 | @defmacx HAVE_POST_MODIFY_REG | |
df2a54e9 | 5342 | A C expression that is nonzero if the machine supports pre- or |
7a6bd5ae | 5343 | post-address side-effect generation involving a register displacement. |
a2c4f8e0 | 5344 | @end defmac |
864bcaa7 | 5345 | |
a2c4f8e0 | 5346 | @defmac CONSTANT_ADDRESS_P (@var{x}) |
feca2ed3 JW |
5347 | A C expression that is 1 if the RTX @var{x} is a constant which |
5348 | is a valid address. On most machines, this can be defined as | |
5349 | @code{CONSTANT_P (@var{x})}, but a few machines are more restrictive | |
5350 | in which constant addresses are supported. | |
a2c4f8e0 | 5351 | @end defmac |
feca2ed3 | 5352 | |
a2c4f8e0 ZW |
5353 | @defmac CONSTANT_P (@var{x}) |
5354 | @code{CONSTANT_P}, which is defined by target-independent code, | |
5355 | accepts integer-values expressions whose values are not explicitly | |
5356 | known, such as @code{symbol_ref}, @code{label_ref}, and @code{high} | |
5357 | expressions and @code{const} arithmetic expressions, in addition to | |
5358 | @code{const_int} and @code{const_double} expressions. | |
5359 | @end defmac | |
feca2ed3 | 5360 | |
a2c4f8e0 | 5361 | @defmac MAX_REGS_PER_ADDRESS |
feca2ed3 JW |
5362 | A number, the maximum number of registers that can appear in a valid |
5363 | memory address. Note that it is up to you to specify a value equal to | |
c6c3dba9 | 5364 | the maximum number that @code{TARGET_LEGITIMATE_ADDRESS_P} would ever |
feca2ed3 | 5365 | accept. |
a2c4f8e0 | 5366 | @end defmac |
feca2ed3 | 5367 | |
c6c3dba9 PB |
5368 | @deftypefn {Target Hook} TARGET_LEGITIMATE_ADDRESS_P (enum machine_mode @var{mode}, rtx @var{x}, bool @var{strict}) |
5369 | A function that returns whether @var{x} (an RTX) is a legitimate memory | |
5370 | address on the target machine for a memory operand of mode @var{mode}. | |
feca2ed3 | 5371 | |
c6c3dba9 PB |
5372 | Legitimate addresses are defined in two variants: a strict variant and a |
5373 | non-strict one. The @code{strict} parameter chooses which variant is | |
5374 | desired by the caller. | |
feca2ed3 | 5375 | |
c6c3dba9 PB |
5376 | The strict variant is used in the reload pass. It must be defined so |
5377 | that any pseudo-register that has not been allocated a hard register is | |
5378 | considered a memory reference. This is because in contexts where some | |
5379 | kind of register is required, a pseudo-register with no hard register | |
5380 | must be rejected. For non-hard registers, the strict variant should look | |
5381 | up the @code{reg_renumber} array; it should then proceed using the hard | |
5382 | register number in the array, or treat the pseudo as a memory reference | |
5383 | if the array holds @code{-1}. | |
feca2ed3 JW |
5384 | |
5385 | The non-strict variant is used in other passes. It must be defined to | |
5386 | accept all pseudo-registers in every context where some kind of | |
5387 | register is required. | |
5388 | ||
feca2ed3 JW |
5389 | Normally, constant addresses which are the sum of a @code{symbol_ref} |
5390 | and an integer are stored inside a @code{const} RTX to mark them as | |
5391 | constant. Therefore, there is no need to recognize such sums | |
5392 | specifically as legitimate addresses. Normally you would simply | |
5393 | recognize any @code{const} as legitimate. | |
5394 | ||
5395 | Usually @code{PRINT_OPERAND_ADDRESS} is not prepared to handle constant | |
5396 | sums that are not marked with @code{const}. It assumes that a naked | |
5397 | @code{plus} indicates indexing. If so, then you @emph{must} reject such | |
5398 | naked constant sums as illegitimate addresses, so that none of them will | |
5399 | be given to @code{PRINT_OPERAND_ADDRESS}. | |
5400 | ||
fb49053f | 5401 | @cindex @code{TARGET_ENCODE_SECTION_INFO} and address validation |
feca2ed3 JW |
5402 | On some machines, whether a symbolic address is legitimate depends on |
5403 | the section that the address refers to. On these machines, define the | |
fb49053f RH |
5404 | target hook @code{TARGET_ENCODE_SECTION_INFO} to store the information |
5405 | into the @code{symbol_ref}, and then check for it here. When you see a | |
feca2ed3 JW |
5406 | @code{const}, you will have to look inside it to find the |
5407 | @code{symbol_ref} in order to determine the section. @xref{Assembler | |
5408 | Format}. | |
c6c3dba9 PB |
5409 | |
5410 | @cindex @code{GO_IF_LEGITIMATE_ADDRESS} | |
5411 | Some ports are still using a deprecated legacy substitute for | |
5412 | this hook, the @code{GO_IF_LEGITIMATE_ADDRESS} macro. This macro | |
5413 | has this syntax: | |
5414 | ||
5415 | @example | |
5416 | #define GO_IF_LEGITIMATE_ADDRESS (@var{mode}, @var{x}, @var{label}) | |
5417 | @end example | |
5418 | ||
5419 | @noindent | |
5420 | and should @code{goto @var{label}} if the address @var{x} is a valid | |
5421 | address on the target machine for a memory operand of mode @var{mode}. | |
5422 | Whether the strict or non-strict variants are desired is defined by | |
5423 | the @code{REG_OK_STRICT} macro introduced earlier in this section. | |
5424 | Using the hook is usually simpler because it limits the number of | |
5425 | files that are recompiled when changes are made. | |
5426 | @end deftypefn | |
feca2ed3 | 5427 | |
a4edaf83 AK |
5428 | @defmac TARGET_MEM_CONSTRAINT |
5429 | A single character to be used instead of the default @code{'m'} | |
5430 | character for general memory addresses. This defines the constraint | |
5431 | letter which matches the memory addresses accepted by | |
c6c3dba9 | 5432 | @code{TARGET_LEGITIMATE_ADDRESS_P}. Define this macro if you want to |
a4edaf83 AK |
5433 | support new address formats in your back end without changing the |
5434 | semantics of the @code{'m'} constraint. This is necessary in order to | |
5435 | preserve functionality of inline assembly constructs using the | |
5436 | @code{'m'} constraint. | |
5437 | @end defmac | |
5438 | ||
a2c4f8e0 | 5439 | @defmac FIND_BASE_TERM (@var{x}) |
a9e6fc5a RS |
5440 | A C expression to determine the base term of address @var{x}, |
5441 | or to provide a simplified version of @var{x} from which @file{alias.c} | |
53451050 RS |
5442 | can easily find the base term. This macro is used in only two places: |
5443 | @code{find_base_value} and @code{find_base_term} in @file{alias.c}. | |
b949ea8b JW |
5444 | |
5445 | It is always safe for this macro to not be defined. It exists so | |
5446 | that alias analysis can understand machine-dependent addresses. | |
5447 | ||
5448 | The typical use of this macro is to handle addresses containing | |
161d7b59 | 5449 | a label_ref or symbol_ref within an UNSPEC@. |
a2c4f8e0 | 5450 | @end defmac |
b949ea8b | 5451 | |
506d7b68 PB |
5452 | @deftypefn {Target Hook} rtx TARGET_LEGITIMIZE_ADDRESS (rtx @var{x}, rtx @var{oldx}, enum machine_mode @var{mode}) |
5453 | This hook is given an invalid memory address @var{x} for an | |
5454 | operand of mode @var{mode} and should try to return a valid memory | |
5455 | address. | |
feca2ed3 JW |
5456 | |
5457 | @findex break_out_memory_refs | |
5458 | @var{x} will always be the result of a call to @code{break_out_memory_refs}, | |
5459 | and @var{oldx} will be the operand that was given to that function to produce | |
5460 | @var{x}. | |
5461 | ||
506d7b68 | 5462 | The code of the hook should not alter the substructure of |
feca2ed3 | 5463 | @var{x}. If it transforms @var{x} into a more legitimate form, it |
506d7b68 | 5464 | should return the new @var{x}. |
feca2ed3 | 5465 | |
506d7b68 PB |
5466 | It is not necessary for this hook to come up with a legitimate address. |
5467 | The compiler has standard ways of doing so in all cases. In fact, it | |
5468 | is safe to omit this hook or make it return @var{x} if it cannot find | |
5469 | a valid way to legitimize the address. But often a machine-dependent | |
5470 | strategy can generate better code. | |
5471 | @end deftypefn | |
feca2ed3 | 5472 | |
a2c4f8e0 | 5473 | @defmac LEGITIMIZE_RELOAD_ADDRESS (@var{x}, @var{mode}, @var{opnum}, @var{type}, @var{ind_levels}, @var{win}) |
a9a2595b JR |
5474 | A C compound statement that attempts to replace @var{x}, which is an address |
5475 | that needs reloading, with a valid memory address for an operand of mode | |
5476 | @var{mode}. @var{win} will be a C statement label elsewhere in the code. | |
5477 | It is not necessary to define this macro, but it might be useful for | |
02f52e19 | 5478 | performance reasons. |
a9a2595b JR |
5479 | |
5480 | For example, on the i386, it is sometimes possible to use a single | |
5481 | reload register instead of two by reloading a sum of two pseudo | |
5482 | registers into a register. On the other hand, for number of RISC | |
5483 | processors offsets are limited so that often an intermediate address | |
5484 | needs to be generated in order to address a stack slot. By defining | |
aee96fe9 | 5485 | @code{LEGITIMIZE_RELOAD_ADDRESS} appropriately, the intermediate addresses |
a9a2595b JR |
5486 | generated for adjacent some stack slots can be made identical, and thus |
5487 | be shared. | |
5488 | ||
39bdfaa0 RH |
5489 | @emph{Note}: This macro should be used with caution. It is necessary |
5490 | to know something of how reload works in order to effectively use this, | |
5491 | and it is quite easy to produce macros that build in too much knowledge | |
5492 | of reload internals. | |
a9a2595b | 5493 | |
5f0c590d JL |
5494 | @emph{Note}: This macro must be able to reload an address created by a |
5495 | previous invocation of this macro. If it fails to handle such addresses | |
5496 | then the compiler may generate incorrect code or abort. | |
5497 | ||
a9a2595b | 5498 | @findex push_reload |
39bdfaa0 RH |
5499 | The macro definition should use @code{push_reload} to indicate parts that |
5500 | need reloading; @var{opnum}, @var{type} and @var{ind_levels} are usually | |
5501 | suitable to be passed unaltered to @code{push_reload}. | |
a9a2595b | 5502 | |
39bdfaa0 | 5503 | The code generated by this macro must not alter the substructure of |
a9a2595b JR |
5504 | @var{x}. If it transforms @var{x} into a more legitimate form, it |
5505 | should assign @var{x} (which will always be a C variable) a new value. | |
5506 | This also applies to parts that you change indirectly by calling | |
5507 | @code{push_reload}. | |
5508 | ||
39bdfaa0 RH |
5509 | @findex strict_memory_address_p |
5510 | The macro definition may use @code{strict_memory_address_p} to test if | |
5511 | the address has become legitimate. | |
5512 | ||
a9a2595b JR |
5513 | @findex copy_rtx |
5514 | If you want to change only a part of @var{x}, one standard way of doing | |
ab873839 | 5515 | this is to use @code{copy_rtx}. Note, however, that it unshares only a |
a9a2595b | 5516 | single level of rtl. Thus, if the part to be changed is not at the |
c771326b | 5517 | top level, you'll need to replace first the top level. |
a9a2595b JR |
5518 | It is not necessary for this macro to come up with a legitimate |
5519 | address; but often a machine-dependent strategy can generate better code. | |
a2c4f8e0 | 5520 | @end defmac |
a9a2595b | 5521 | |
a2c4f8e0 | 5522 | @defmac GO_IF_MODE_DEPENDENT_ADDRESS (@var{addr}, @var{label}) |
feca2ed3 JW |
5523 | A C statement or compound statement with a conditional @code{goto |
5524 | @var{label};} executed if memory address @var{x} (an RTX) can have | |
5525 | different meanings depending on the machine mode of the memory | |
5526 | reference it is used for or if the address is valid for some modes | |
5527 | but not others. | |
5528 | ||
5529 | Autoincrement and autodecrement addresses typically have mode-dependent | |
5530 | effects because the amount of the increment or decrement is the size | |
5531 | of the operand being addressed. Some machines have other mode-dependent | |
5532 | addresses. Many RISC machines have no mode-dependent addresses. | |
5533 | ||
5534 | You may assume that @var{addr} is a valid address for the machine. | |
a2c4f8e0 | 5535 | @end defmac |
feca2ed3 | 5536 | |
a2c4f8e0 | 5537 | @defmac LEGITIMATE_CONSTANT_P (@var{x}) |
feca2ed3 JW |
5538 | A C expression that is nonzero if @var{x} is a legitimate constant for |
5539 | an immediate operand on the target machine. You can assume that | |
5540 | @var{x} satisfies @code{CONSTANT_P}, so you need not check this. In fact, | |
5541 | @samp{1} is a suitable definition for this macro on machines where | |
bd819a4a | 5542 | anything @code{CONSTANT_P} is valid. |
a2c4f8e0 | 5543 | @end defmac |
feca2ed3 | 5544 | |
73f8783a RS |
5545 | @deftypefn {Target Hook} rtx TARGET_DELEGITIMIZE_ADDRESS (rtx @var{x}) |
5546 | This hook is used to undo the possibly obfuscating effects of the | |
5547 | @code{LEGITIMIZE_ADDRESS} and @code{LEGITIMIZE_RELOAD_ADDRESS} target | |
5548 | macros. Some backend implementations of these macros wrap symbol | |
5549 | references inside an @code{UNSPEC} rtx to represent PIC or similar | |
5550 | addressing modes. This target hook allows GCC's optimizers to understand | |
5551 | the semantics of these opaque @code{UNSPEC}s by converting them back | |
5552 | into their original form. | |
5553 | @end deftypefn | |
5554 | ||
d3da4d14 RH |
5555 | @deftypefn {Target Hook} bool TARGET_CANNOT_FORCE_CONST_MEM (rtx @var{x}) |
5556 | This hook should return true if @var{x} is of a form that cannot (or | |
5557 | should not) be spilled to the constant pool. The default version of | |
5558 | this hook returns false. | |
5559 | ||
5560 | The primary reason to define this hook is to prevent reload from | |
5561 | deciding that a non-legitimate constant would be better reloaded | |
5562 | from the constant pool instead of spilling and reloading a register | |
5563 | holding the constant. This restriction is often true of addresses | |
5564 | of TLS symbols for various targets. | |
5565 | @end deftypefn | |
5566 | ||
aacd3885 RS |
5567 | @deftypefn {Target Hook} bool TARGET_USE_BLOCKS_FOR_CONSTANT_P (enum machine_mode @var{mode}, rtx @var{x}) |
5568 | This hook should return true if pool entries for constant @var{x} can | |
5569 | be placed in an @code{object_block} structure. @var{mode} is the mode | |
5570 | of @var{x}. | |
5571 | ||
5572 | The default version returns false for all constants. | |
5573 | @end deftypefn | |
5574 | ||
ac10986f | 5575 | @deftypefn {Target Hook} tree TARGET_BUILTIN_RECIPROCAL (enum tree_code @var{fn}, bool @var{tm_fn}, bool @var{sqrt}) |
6b889d89 | 5576 | This hook should return the DECL of a function that implements reciprocal of |
ac10986f UB |
5577 | the builtin function with builtin function code @var{fn}, or |
5578 | @code{NULL_TREE} if such a function is not available. @var{tm_fn} is true | |
5579 | when @var{fn} is a code of a machine-dependent builtin function. When | |
5580 | @var{sqrt} is true, additional optimizations that apply only to the reciprocal | |
5581 | of a square root function are performed, and only reciprocals of @code{sqrt} | |
5582 | function are valid. | |
6b889d89 UB |
5583 | @end deftypefn |
5584 | ||
d16b59fa DN |
5585 | @deftypefn {Target Hook} tree TARGET_VECTORIZE_BUILTIN_MASK_FOR_LOAD (void) |
5586 | This hook should return the DECL of a function @var{f} that given an | |
5587 | address @var{addr} as an argument returns a mask @var{m} that can be | |
083cad55 | 5588 | used to extract from two vectors the relevant data that resides in |
d16b59fa DN |
5589 | @var{addr} in case @var{addr} is not properly aligned. |
5590 | ||
ab873839 | 5591 | The autovectorizer, when vectorizing a load operation from an address |
d16b59fa DN |
5592 | @var{addr} that may be unaligned, will generate two vector loads from |
5593 | the two aligned addresses around @var{addr}. It then generates a | |
5594 | @code{REALIGN_LOAD} operation to extract the relevant data from the | |
5595 | two loaded vectors. The first two arguments to @code{REALIGN_LOAD}, | |
5596 | @var{v1} and @var{v2}, are the two vectors, each of size @var{VS}, and | |
5597 | the third argument, @var{OFF}, defines how the data will be extracted | |
5598 | from these two vectors: if @var{OFF} is 0, then the returned vector is | |
083cad55 EC |
5599 | @var{v2}; otherwise, the returned vector is composed from the last |
5600 | @var{VS}-@var{OFF} elements of @var{v1} concatenated to the first | |
d16b59fa DN |
5601 | @var{OFF} elements of @var{v2}. |
5602 | ||
5603 | If this hook is defined, the autovectorizer will generate a call | |
5604 | to @var{f} (using the DECL tree that this hook returns) and will | |
5605 | use the return value of @var{f} as the argument @var{OFF} to | |
5606 | @code{REALIGN_LOAD}. Therefore, the mask @var{m} returned by @var{f} | |
083cad55 | 5607 | should comply with the semantics expected by @code{REALIGN_LOAD} |
d16b59fa DN |
5608 | described above. |
5609 | If this hook is not defined, then @var{addr} will be used as | |
5610 | the argument @var{OFF} to @code{REALIGN_LOAD}, in which case the low | |
5611 | log2(@var{VS})-1 bits of @var{addr} will be considered. | |
5612 | @end deftypefn | |
5613 | ||
89d67cca DN |
5614 | @deftypefn {Target Hook} tree TARGET_VECTORIZE_BUILTIN_MUL_WIDEN_EVEN (tree @var{x}) |
5615 | This hook should return the DECL of a function @var{f} that implements | |
5616 | widening multiplication of the even elements of two input vectors of type @var{x}. | |
5617 | ||
5618 | If this hook is defined, the autovectorizer will use it along with the | |
5619 | @code{TARGET_VECTORIZE_BUILTIN_MUL_WIDEN_ODD} target hook when vectorizing | |
5620 | widening multiplication in cases that the order of the results does not have to be | |
021efafc | 5621 | preserved (e.g.@: used only by a reduction computation). Otherwise, the |
89d67cca DN |
5622 | @code{widen_mult_hi/lo} idioms will be used. |
5623 | @end deftypefn | |
5624 | ||
5625 | @deftypefn {Target Hook} tree TARGET_VECTORIZE_BUILTIN_MUL_WIDEN_ODD (tree @var{x}) | |
5626 | This hook should return the DECL of a function @var{f} that implements | |
5627 | widening multiplication of the odd elements of two input vectors of type @var{x}. | |
5628 | ||
5629 | If this hook is defined, the autovectorizer will use it along with the | |
5630 | @code{TARGET_VECTORIZE_BUILTIN_MUL_WIDEN_EVEN} target hook when vectorizing | |
5631 | widening multiplication in cases that the order of the results does not have to be | |
021efafc | 5632 | preserved (e.g.@: used only by a reduction computation). Otherwise, the |
89d67cca DN |
5633 | @code{widen_mult_hi/lo} idioms will be used. |
5634 | @end deftypefn | |
5635 | ||
f57d17f1 TM |
5636 | @deftypefn {Target Hook} tree TARGET_VECTORIZE_BUILTIN_CONVERSION (enum tree_code @var{code}, tree @var{type}) |
5637 | This hook should return the DECL of a function that implements conversion of the | |
5638 | input vector of type @var{type}. | |
5639 | If @var{type} is an integral type, the result of the conversion is a vector of | |
5640 | floating-point type of the same size. | |
5641 | If @var{type} is a floating-point type, the result of the conversion is a vector | |
5642 | of integral type of the same size. | |
5643 | @var{code} specifies how the conversion is to be applied | |
5644 | (truncation, rounding, etc.). | |
5645 | ||
5646 | If this hook is defined, the autovectorizer will use the | |
5647 | @code{TARGET_VECTORIZE_BUILTIN_CONVERSION} target hook when vectorizing | |
5648 | conversion. Otherwise, it will return @code{NULL_TREE}. | |
5649 | @end deftypefn | |
5650 | ||
b95becfc | 5651 | @deftypefn {Target Hook} tree TARGET_VECTORIZE_BUILTIN_VECTORIZED_FUNCTION (enum built_in_function @var{code}, tree @var{vec_type_out}, tree @var{vec_type_in}) |
2505a3f2 RG |
5652 | This hook should return the decl of a function that implements the vectorized |
5653 | variant of the builtin function with builtin function code @var{code} or | |
5654 | @code{NULL_TREE} if such a function is not available. The return type of | |
b95becfc RG |
5655 | the vectorized function shall be of vector type @var{vec_type_out} and the |
5656 | argument types should be @var{vec_type_in}. | |
2505a3f2 RG |
5657 | @end deftypefn |
5658 | ||
aacd3885 RS |
5659 | @node Anchored Addresses |
5660 | @section Anchored Addresses | |
5661 | @cindex anchored addresses | |
5662 | @cindex @option{-fsection-anchors} | |
5663 | ||
5664 | GCC usually addresses every static object as a separate entity. | |
5665 | For example, if we have: | |
5666 | ||
5667 | @smallexample | |
5668 | static int a, b, c; | |
5669 | int foo (void) @{ return a + b + c; @} | |
5670 | @end smallexample | |
5671 | ||
5672 | the code for @code{foo} will usually calculate three separate symbolic | |
5673 | addresses: those of @code{a}, @code{b} and @code{c}. On some targets, | |
5674 | it would be better to calculate just one symbolic address and access | |
5675 | the three variables relative to it. The equivalent pseudocode would | |
5676 | be something like: | |
5677 | ||
5678 | @smallexample | |
5679 | int foo (void) | |
5680 | @{ | |
5681 | register int *xr = &x; | |
5682 | return xr[&a - &x] + xr[&b - &x] + xr[&c - &x]; | |
5683 | @} | |
5684 | @end smallexample | |
5685 | ||
5686 | (which isn't valid C). We refer to shared addresses like @code{x} as | |
5687 | ``section anchors''. Their use is controlled by @option{-fsection-anchors}. | |
5688 | ||
5689 | The hooks below describe the target properties that GCC needs to know | |
5690 | in order to make effective use of section anchors. It won't use | |
5691 | section anchors at all unless either @code{TARGET_MIN_ANCHOR_OFFSET} | |
5692 | or @code{TARGET_MAX_ANCHOR_OFFSET} is set to a nonzero value. | |
5693 | ||
9e3be889 | 5694 | @deftypevr {Target Hook} HOST_WIDE_INT TARGET_MIN_ANCHOR_OFFSET |
aacd3885 RS |
5695 | The minimum offset that should be applied to a section anchor. |
5696 | On most targets, it should be the smallest offset that can be | |
5697 | applied to a base register while still giving a legitimate address | |
5698 | for every mode. The default value is 0. | |
9e3be889 | 5699 | @end deftypevr |
aacd3885 | 5700 | |
9e3be889 | 5701 | @deftypevr {Target Hook} HOST_WIDE_INT TARGET_MAX_ANCHOR_OFFSET |
aacd3885 RS |
5702 | Like @code{TARGET_MIN_ANCHOR_OFFSET}, but the maximum (inclusive) |
5703 | offset that should be applied to section anchors. The default | |
5704 | value is 0. | |
9e3be889 | 5705 | @end deftypevr |
aacd3885 RS |
5706 | |
5707 | @deftypefn {Target Hook} void TARGET_ASM_OUTPUT_ANCHOR (rtx @var{x}) | |
5708 | Write the assembly code to define section anchor @var{x}, which is a | |
5709 | @code{SYMBOL_REF} for which @samp{SYMBOL_REF_ANCHOR_P (@var{x})} is true. | |
5710 | The hook is called with the assembly output position set to the beginning | |
5711 | of @code{SYMBOL_REF_BLOCK (@var{x})}. | |
5712 | ||
5713 | If @code{ASM_OUTPUT_DEF} is available, the hook's default definition uses | |
5714 | it to define the symbol as @samp{. + SYMBOL_REF_BLOCK_OFFSET (@var{x})}. | |
5715 | If @code{ASM_OUTPUT_DEF} is not available, the hook's default definition | |
5716 | is @code{NULL}, which disables the use of section anchors altogether. | |
5717 | @end deftypefn | |
5718 | ||
5719 | @deftypefn {Target Hook} bool TARGET_USE_ANCHORS_FOR_SYMBOL_P (rtx @var{x}) | |
5720 | Return true if GCC should attempt to use anchors to access @code{SYMBOL_REF} | |
3fa9c136 | 5721 | @var{x}. You can assume @samp{SYMBOL_REF_HAS_BLOCK_INFO_P (@var{x})} and |
aacd3885 RS |
5722 | @samp{!SYMBOL_REF_ANCHOR_P (@var{x})}. |
5723 | ||
5724 | The default version is correct for most targets, but you might need to | |
5725 | intercept this hook to handle things like target-specific attributes | |
5726 | or target-specific sections. | |
5727 | @end deftypefn | |
5728 | ||
feca2ed3 JW |
5729 | @node Condition Code |
5730 | @section Condition Code Status | |
5731 | @cindex condition code status | |
5732 | ||
f90b7a5a PB |
5733 | The macros in this section can be split in two families, according to the |
5734 | two ways of representing condition codes in GCC. | |
5735 | ||
5736 | The first representation is the so called @code{(cc0)} representation | |
5737 | (@pxref{Jump Patterns}), where all instructions can have an implicit | |
5738 | clobber of the condition codes. The second is the condition code | |
5739 | register representation, which provides better schedulability for | |
5740 | architectures that do have a condition code register, but on which | |
5741 | most instructions do not affect it. The latter category includes | |
5742 | most RISC machines. | |
5743 | ||
5744 | The implicit clobbering poses a strong restriction on the placement of | |
5745 | the definition and use of the condition code, which need to be in adjacent | |
5746 | insns for machines using @code{(cc0)}. This can prevent important | |
5747 | optimizations on some machines. For example, on the IBM RS/6000, there | |
5748 | is a delay for taken branches unless the condition code register is set | |
5749 | three instructions earlier than the conditional branch. The instruction | |
5750 | scheduler cannot perform this optimization if it is not permitted to | |
5751 | separate the definition and use of the condition code register. | |
5752 | ||
5753 | For this reason, it is possible and suggested to use a register to | |
5754 | represent the condition code for new ports. If there is a specific | |
5755 | condition code register in the machine, use a hard register. If the | |
5756 | condition code or comparison result can be placed in any general register, | |
5757 | or if there are multiple condition registers, use a pseudo register. | |
5758 | Registers used to store the condition code value will usually have a mode | |
5759 | that is in class @code{MODE_CC}. | |
5760 | ||
5761 | Alternatively, you can use @code{BImode} if the comparison operator is | |
5762 | specified already in the compare instruction. In this case, you are not | |
5763 | interested in most macros in this section. | |
5764 | ||
5765 | @menu | |
5766 | * CC0 Condition Codes:: Old style representation of condition codes. | |
5767 | * MODE_CC Condition Codes:: Modern representation of condition codes. | |
5768 | * Cond. Exec. Macros:: Macros to control conditional execution. | |
5769 | @end menu | |
5770 | ||
5771 | @node CC0 Condition Codes | |
5772 | @subsection Representation of condition codes using @code{(cc0)} | |
5773 | @findex cc0 | |
feca2ed3 JW |
5774 | |
5775 | @findex cc_status | |
5776 | The file @file{conditions.h} defines a variable @code{cc_status} to | |
5777 | describe how the condition code was computed (in case the interpretation of | |
5778 | the condition code depends on the instruction that it was set by). This | |
5779 | variable contains the RTL expressions on which the condition code is | |
5780 | currently based, and several standard flags. | |
5781 | ||
5782 | Sometimes additional machine-specific flags must be defined in the machine | |
5783 | description header file. It can also add additional machine-specific | |
5784 | information by defining @code{CC_STATUS_MDEP}. | |
5785 | ||
a2c4f8e0 | 5786 | @defmac CC_STATUS_MDEP |
feca2ed3 JW |
5787 | C code for a data type which is used for declaring the @code{mdep} |
5788 | component of @code{cc_status}. It defaults to @code{int}. | |
5789 | ||
5790 | This macro is not used on machines that do not use @code{cc0}. | |
a2c4f8e0 | 5791 | @end defmac |
feca2ed3 | 5792 | |
a2c4f8e0 | 5793 | @defmac CC_STATUS_MDEP_INIT |
feca2ed3 JW |
5794 | A C expression to initialize the @code{mdep} field to ``empty''. |
5795 | The default definition does nothing, since most machines don't use | |
5796 | the field anyway. If you want to use the field, you should probably | |
5797 | define this macro to initialize it. | |
5798 | ||
5799 | This macro is not used on machines that do not use @code{cc0}. | |
a2c4f8e0 | 5800 | @end defmac |
feca2ed3 | 5801 | |
a2c4f8e0 | 5802 | @defmac NOTICE_UPDATE_CC (@var{exp}, @var{insn}) |
feca2ed3 JW |
5803 | A C compound statement to set the components of @code{cc_status} |
5804 | appropriately for an insn @var{insn} whose body is @var{exp}. It is | |
5805 | this macro's responsibility to recognize insns that set the condition | |
5806 | code as a byproduct of other activity as well as those that explicitly | |
5807 | set @code{(cc0)}. | |
5808 | ||
5809 | This macro is not used on machines that do not use @code{cc0}. | |
5810 | ||
5811 | If there are insns that do not set the condition code but do alter | |
5812 | other machine registers, this macro must check to see whether they | |
5813 | invalidate the expressions that the condition code is recorded as | |
5814 | reflecting. For example, on the 68000, insns that store in address | |
5815 | registers do not set the condition code, which means that usually | |
5816 | @code{NOTICE_UPDATE_CC} can leave @code{cc_status} unaltered for such | |
5817 | insns. But suppose that the previous insn set the condition code | |
5818 | based on location @samp{a4@@(102)} and the current insn stores a new | |
5819 | value in @samp{a4}. Although the condition code is not changed by | |
5820 | this, it will no longer be true that it reflects the contents of | |
5821 | @samp{a4@@(102)}. Therefore, @code{NOTICE_UPDATE_CC} must alter | |
5822 | @code{cc_status} in this case to say that nothing is known about the | |
5823 | condition code value. | |
5824 | ||
5825 | The definition of @code{NOTICE_UPDATE_CC} must be prepared to deal | |
5826 | with the results of peephole optimization: insns whose patterns are | |
5827 | @code{parallel} RTXs containing various @code{reg}, @code{mem} or | |
5828 | constants which are just the operands. The RTL structure of these | |
5829 | insns is not sufficient to indicate what the insns actually do. What | |
5830 | @code{NOTICE_UPDATE_CC} should do when it sees one is just to run | |
5831 | @code{CC_STATUS_INIT}. | |
5832 | ||
5833 | A possible definition of @code{NOTICE_UPDATE_CC} is to call a function | |
5834 | that looks at an attribute (@pxref{Insn Attributes}) named, for example, | |
5835 | @samp{cc}. This avoids having detailed information about patterns in | |
5836 | two places, the @file{md} file and in @code{NOTICE_UPDATE_CC}. | |
a2c4f8e0 | 5837 | @end defmac |
feca2ed3 | 5838 | |
f90b7a5a PB |
5839 | @node MODE_CC Condition Codes |
5840 | @subsection Representation of condition codes using registers | |
5841 | @findex CCmode | |
5842 | @findex MODE_CC | |
5843 | ||
a2c4f8e0 | 5844 | @defmac SELECT_CC_MODE (@var{op}, @var{x}, @var{y}) |
f90b7a5a PB |
5845 | On many machines, the condition code may be produced by other instructions |
5846 | than compares, for example the branch can use directly the condition | |
5847 | code set by a subtract instruction. However, on some machines | |
5848 | when the condition code is set this way some bits (such as the overflow | |
5849 | bit) are not set in the same way as a test instruction, so that a different | |
5850 | branch instruction must be used for some conditional branches. When | |
5851 | this happens, use the machine mode of the condition code register to | |
5852 | record different formats of the condition code register. Modes can | |
5853 | also be used to record which compare instruction (e.g. a signed or an | |
5854 | unsigned comparison) produced the condition codes. | |
5855 | ||
5856 | If other modes than @code{CCmode} are required, add them to | |
5857 | @file{@var{machine}-modes.def} and define @code{SELECT_CC_MODE} to choose | |
5858 | a mode given an operand of a compare. This is needed because the modes | |
5859 | have to be chosen not only during RTL generation but also, for example, | |
5860 | by instruction combination. The result of @code{SELECT_CC_MODE} should | |
5861 | be consistent with the mode used in the patterns; for example to support | |
5862 | the case of the add on the SPARC discussed above, we have the pattern | |
5863 | ||
5864 | @smallexample | |
5865 | (define_insn "" | |
5866 | [(set (reg:CC_NOOV 0) | |
5867 | (compare:CC_NOOV | |
5868 | (plus:SI (match_operand:SI 0 "register_operand" "%r") | |
5869 | (match_operand:SI 1 "arith_operand" "rI")) | |
5870 | (const_int 0)))] | |
5871 | "" | |
5872 | "@dots{}") | |
5873 | @end smallexample | |
5874 | ||
5875 | @noindent | |
5876 | together with a @code{SELECT_CC_MODE} that returns @code{CC_NOOVmode} | |
5877 | for comparisons whose argument is a @code{plus}: | |
feca2ed3 JW |
5878 | |
5879 | @smallexample | |
5880 | #define SELECT_CC_MODE(OP,X,Y) \ | |
5881 | (GET_MODE_CLASS (GET_MODE (X)) == MODE_FLOAT \ | |
5882 | ? ((OP == EQ || OP == NE) ? CCFPmode : CCFPEmode) \ | |
5883 | : ((GET_CODE (X) == PLUS || GET_CODE (X) == MINUS \ | |
5884 | || GET_CODE (X) == NEG) \ | |
5885 | ? CC_NOOVmode : CCmode)) | |
5886 | @end smallexample | |
5887 | ||
f90b7a5a PB |
5888 | Another reason to use modes is to retain information on which operands |
5889 | were used by the comparison; see @code{REVERSIBLE_CC_MODE} later in | |
5890 | this section. | |
5891 | ||
94134f42 ZW |
5892 | You should define this macro if and only if you define extra CC modes |
5893 | in @file{@var{machine}-modes.def}. | |
a2c4f8e0 | 5894 | @end defmac |
feca2ed3 | 5895 | |
a2c4f8e0 | 5896 | @defmac CANONICALIZE_COMPARISON (@var{code}, @var{op0}, @var{op1}) |
8760eaae | 5897 | On some machines not all possible comparisons are defined, but you can |
feca2ed3 JW |
5898 | convert an invalid comparison into a valid one. For example, the Alpha |
5899 | does not have a @code{GT} comparison, but you can use an @code{LT} | |
5900 | comparison instead and swap the order of the operands. | |
5901 | ||
5902 | On such machines, define this macro to be a C statement to do any | |
5903 | required conversions. @var{code} is the initial comparison code | |
5904 | and @var{op0} and @var{op1} are the left and right operands of the | |
5905 | comparison, respectively. You should modify @var{code}, @var{op0}, and | |
5906 | @var{op1} as required. | |
5907 | ||
a3a15b4d | 5908 | GCC will not assume that the comparison resulting from this macro is |
feca2ed3 JW |
5909 | valid but will see if the resulting insn matches a pattern in the |
5910 | @file{md} file. | |
5911 | ||
5912 | You need not define this macro if it would never change the comparison | |
5913 | code or operands. | |
a2c4f8e0 | 5914 | @end defmac |
feca2ed3 | 5915 | |
a2c4f8e0 | 5916 | @defmac REVERSIBLE_CC_MODE (@var{mode}) |
feca2ed3 JW |
5917 | A C expression whose value is one if it is always safe to reverse a |
5918 | comparison whose mode is @var{mode}. If @code{SELECT_CC_MODE} | |
5919 | can ever return @var{mode} for a floating-point inequality comparison, | |
5920 | then @code{REVERSIBLE_CC_MODE (@var{mode})} must be zero. | |
5921 | ||
5922 | You need not define this macro if it would always returns zero or if the | |
5923 | floating-point format is anything other than @code{IEEE_FLOAT_FORMAT}. | |
981f6289 | 5924 | For example, here is the definition used on the SPARC, where floating-point |
feca2ed3 JW |
5925 | inequality comparisons are always given @code{CCFPEmode}: |
5926 | ||
5927 | @smallexample | |
5928 | #define REVERSIBLE_CC_MODE(MODE) ((MODE) != CCFPEmode) | |
5929 | @end smallexample | |
a2c4f8e0 | 5930 | @end defmac |
feca2ed3 | 5931 | |
a2c4f8e0 | 5932 | @defmac REVERSE_CONDITION (@var{code}, @var{mode}) |
9e7adcb3 JH |
5933 | A C expression whose value is reversed condition code of the @var{code} for |
5934 | comparison done in CC_MODE @var{mode}. The macro is used only in case | |
5935 | @code{REVERSIBLE_CC_MODE (@var{mode})} is nonzero. Define this macro in case | |
5936 | machine has some non-standard way how to reverse certain conditionals. For | |
5937 | instance in case all floating point conditions are non-trapping, compiler may | |
5938 | freely convert unordered compares to ordered one. Then definition may look | |
5939 | like: | |
5940 | ||
5941 | @smallexample | |
5942 | #define REVERSE_CONDITION(CODE, MODE) \ | |
c771326b | 5943 | ((MODE) != CCFPmode ? reverse_condition (CODE) \ |
9e7adcb3 JH |
5944 | : reverse_condition_maybe_unordered (CODE)) |
5945 | @end smallexample | |
a2c4f8e0 | 5946 | @end defmac |
9e7adcb3 | 5947 | |
e129d93a ILT |
5948 | @deftypefn {Target Hook} bool TARGET_FIXED_CONDITION_CODE_REGS (unsigned int *, unsigned int *) |
5949 | On targets which do not use @code{(cc0)}, and which use a hard | |
5950 | register rather than a pseudo-register to hold condition codes, the | |
5951 | regular CSE passes are often not able to identify cases in which the | |
5952 | hard register is set to a common value. Use this hook to enable a | |
5953 | small pass which optimizes such cases. This hook should return true | |
5954 | to enable this pass, and it should set the integers to which its | |
5955 | arguments point to the hard register numbers used for condition codes. | |
5956 | When there is only one such register, as is true on most systems, the | |
5957 | integer pointed to by the second argument should be set to | |
5958 | @code{INVALID_REGNUM}. | |
5959 | ||
5960 | The default version of this hook returns false. | |
5961 | @end deftypefn | |
5962 | ||
5963 | @deftypefn {Target Hook} enum machine_mode TARGET_CC_MODES_COMPATIBLE (enum machine_mode, enum machine_mode) | |
5964 | On targets which use multiple condition code modes in class | |
5965 | @code{MODE_CC}, it is sometimes the case that a comparison can be | |
5966 | validly done in more than one mode. On such a system, define this | |
5967 | target hook to take two mode arguments and to return a mode in which | |
5968 | both comparisons may be validly done. If there is no such mode, | |
5969 | return @code{VOIDmode}. | |
5970 | ||
5971 | The default version of this hook checks whether the modes are the | |
5972 | same. If they are, it returns that mode. If they are different, it | |
5973 | returns @code{VOIDmode}. | |
5974 | @end deftypefn | |
5975 | ||
f90b7a5a PB |
5976 | @node Cond. Exec. Macros |
5977 | @subsection Macros to control conditional execution | |
5978 | @findex conditional execution | |
5979 | @findex predication | |
5980 | ||
5981 | There is one macro that may need to be defined for targets | |
5982 | supporting conditional execution, independent of how they | |
5983 | represent conditional branches. | |
5984 | ||
5985 | @defmac REVERSE_CONDEXEC_PREDICATES_P (@var{op1}, @var{op2}) | |
5986 | A C expression that returns true if the conditional execution predicate | |
5987 | @var{op1}, a comparison operation, is the inverse of @var{op2} and vice | |
5988 | versa. Define this to return 0 if the target has conditional execution | |
5989 | predicates that cannot be reversed safely. There is no need to validate | |
5990 | that the arguments of op1 and op2 are the same, this is done separately. | |
5991 | If no expansion is specified, this macro is defined as follows: | |
5992 | ||
5993 | @smallexample | |
5994 | #define REVERSE_CONDEXEC_PREDICATES_P (x, y) \ | |
5995 | (GET_CODE ((x)) == reversed_comparison_code ((y), NULL)) | |
5996 | @end smallexample | |
5997 | @end defmac | |
5998 | ||
feca2ed3 JW |
5999 | @node Costs |
6000 | @section Describing Relative Costs of Operations | |
6001 | @cindex costs of instructions | |
6002 | @cindex relative costs | |
6003 | @cindex speed of instructions | |
6004 | ||
6005 | These macros let you describe the relative speed of various operations | |
6006 | on the target machine. | |
6007 | ||
a2c4f8e0 | 6008 | @defmac REGISTER_MOVE_COST (@var{mode}, @var{from}, @var{to}) |
e56b4594 AO |
6009 | A C expression for the cost of moving data of mode @var{mode} from a |
6010 | register in class @var{from} to one in class @var{to}. The classes are | |
6011 | expressed using the enumeration values such as @code{GENERAL_REGS}. A | |
6012 | value of 2 is the default; other values are interpreted relative to | |
6013 | that. | |
feca2ed3 JW |
6014 | |
6015 | It is not required that the cost always equal 2 when @var{from} is the | |
6016 | same as @var{to}; on some machines it is expensive to move between | |
6017 | registers if they are not general registers. | |
6018 | ||
6019 | If reload sees an insn consisting of a single @code{set} between two | |
6020 | hard registers, and if @code{REGISTER_MOVE_COST} applied to their | |
6021 | classes returns a value of 2, reload does not check to ensure that the | |
6022 | constraints of the insn are met. Setting a cost of other than 2 will | |
6023 | allow reload to verify that the constraints are met. You should do this | |
6024 | if the @samp{mov@var{m}} pattern's constraints do not allow such copying. | |
a2c4f8e0 | 6025 | @end defmac |
feca2ed3 | 6026 | |
a2c4f8e0 | 6027 | @defmac MEMORY_MOVE_COST (@var{mode}, @var{class}, @var{in}) |
cbd5b9a2 KR |
6028 | A C expression for the cost of moving data of mode @var{mode} between a |
6029 | register of class @var{class} and memory; @var{in} is zero if the value | |
df2a54e9 | 6030 | is to be written to memory, nonzero if it is to be read in. This cost |
473fe49b KR |
6031 | is relative to those in @code{REGISTER_MOVE_COST}. If moving between |
6032 | registers and memory is more expensive than between two registers, you | |
6033 | should define this macro to express the relative cost. | |
6034 | ||
a3a15b4d | 6035 | If you do not define this macro, GCC uses a default cost of 4 plus |
38e01259 | 6036 | the cost of copying via a secondary reload register, if one is |
473fe49b KR |
6037 | needed. If your machine requires a secondary reload register to copy |
6038 | between memory and a register of @var{class} but the reload mechanism is | |
6039 | more complex than copying via an intermediate, define this macro to | |
6040 | reflect the actual cost of the move. | |
6041 | ||
a3a15b4d | 6042 | GCC defines the function @code{memory_move_secondary_cost} if |
473fe49b KR |
6043 | secondary reloads are needed. It computes the costs due to copying via |
6044 | a secondary register. If your machine copies from memory using a | |
6045 | secondary register in the conventional way but the default base value of | |
6046 | 4 is not correct for your machine, define this macro to add some other | |
6047 | value to the result of that function. The arguments to that function | |
6048 | are the same as to this macro. | |
a2c4f8e0 | 6049 | @end defmac |
cbd5b9a2 | 6050 | |
3a4fd356 JH |
6051 | @defmac BRANCH_COST (@var{speed_p}, @var{predictable_p}) |
6052 | A C expression for the cost of a branch instruction. A value of 1 is the | |
6053 | default; other values are interpreted relative to that. Parameter @var{speed_p} | |
6054 | is true when the branch in question should be optimized for speed. When | |
6055 | it is false, @code{BRANCH_COST} should be returning value optimal for code size | |
6056 | rather then performance considerations. @var{predictable_p} is true for well | |
6057 | predictable branches. On many architectures the @code{BRANCH_COST} can be | |
6058 | reduced then. | |
a2c4f8e0 | 6059 | @end defmac |
feca2ed3 JW |
6060 | |
6061 | Here are additional macros which do not specify precise relative costs, | |
a3a15b4d | 6062 | but only that certain actions are more expensive than GCC would |
feca2ed3 JW |
6063 | ordinarily expect. |
6064 | ||
a2c4f8e0 | 6065 | @defmac SLOW_BYTE_ACCESS |
feca2ed3 | 6066 | Define this macro as a C expression which is nonzero if accessing less |
e979f9e8 | 6067 | than a word of memory (i.e.@: a @code{char} or a @code{short}) is no |
feca2ed3 JW |
6068 | faster than accessing a word of memory, i.e., if such access |
6069 | require more than one instruction or if there is no difference in cost | |
6070 | between byte and (aligned) word loads. | |
6071 | ||
6072 | When this macro is not defined, the compiler will access a field by | |
6073 | finding the smallest containing object; when it is defined, a fullword | |
6074 | load will be used if alignment permits. Unless bytes accesses are | |
6075 | faster than word accesses, using word accesses is preferable since it | |
6076 | may eliminate subsequent memory access if subsequent accesses occur to | |
6077 | other fields in the same word of the structure, but to different bytes. | |
a2c4f8e0 | 6078 | @end defmac |
feca2ed3 | 6079 | |
a2c4f8e0 | 6080 | @defmac SLOW_UNALIGNED_ACCESS (@var{mode}, @var{alignment}) |
5fad8ebf DE |
6081 | Define this macro to be the value 1 if memory accesses described by the |
6082 | @var{mode} and @var{alignment} parameters have a cost many times greater | |
6083 | than aligned accesses, for example if they are emulated in a trap | |
6084 | handler. | |
feca2ed3 | 6085 | |
df2a54e9 JM |
6086 | When this macro is nonzero, the compiler will act as if |
6087 | @code{STRICT_ALIGNMENT} were nonzero when generating code for block | |
feca2ed3 | 6088 | moves. This can cause significantly more instructions to be produced. |
df2a54e9 | 6089 | Therefore, do not set this macro nonzero if unaligned accesses only add a |
feca2ed3 JW |
6090 | cycle or two to the time for a memory access. |
6091 | ||
6be57663 | 6092 | If the value of this macro is always zero, it need not be defined. If |
df2a54e9 JM |
6093 | this macro is defined, it should produce a nonzero value when |
6094 | @code{STRICT_ALIGNMENT} is nonzero. | |
a2c4f8e0 | 6095 | @end defmac |
feca2ed3 | 6096 | |
a2c4f8e0 | 6097 | @defmac MOVE_RATIO |
9862dea9 | 6098 | The threshold of number of scalar memory-to-memory move insns, @emph{below} |
c5c76735 | 6099 | which a sequence of insns should be generated instead of a |
feca2ed3 JW |
6100 | string move insn or a library call. Increasing the value will always |
6101 | make code faster, but eventually incurs high cost in increased code size. | |
6102 | ||
c5c76735 JL |
6103 | Note that on machines where the corresponding move insn is a |
6104 | @code{define_expand} that emits a sequence of insns, this macro counts | |
6105 | the number of such sequences. | |
9862dea9 | 6106 | |
feca2ed3 | 6107 | If you don't define this, a reasonable default is used. |
a2c4f8e0 | 6108 | @end defmac |
feca2ed3 | 6109 | |
a2c4f8e0 | 6110 | @defmac MOVE_BY_PIECES_P (@var{size}, @var{alignment}) |
fbe1758d AM |
6111 | A C expression used to determine whether @code{move_by_pieces} will be used to |
6112 | copy a chunk of memory, or whether some other block move mechanism | |
6e01bd94 | 6113 | will be used. Defaults to 1 if @code{move_by_pieces_ninsns} returns less |
fbe1758d | 6114 | than @code{MOVE_RATIO}. |
a2c4f8e0 | 6115 | @end defmac |
fbe1758d | 6116 | |
a2c4f8e0 | 6117 | @defmac MOVE_MAX_PIECES |
fbe1758d | 6118 | A C expression used by @code{move_by_pieces} to determine the largest unit |
6e01bd94 | 6119 | a load or store used to copy memory is. Defaults to @code{MOVE_MAX}. |
a2c4f8e0 | 6120 | @end defmac |
fbe1758d | 6121 | |
a2c4f8e0 | 6122 | @defmac CLEAR_RATIO |
78762e3b RS |
6123 | The threshold of number of scalar move insns, @emph{below} which a sequence |
6124 | of insns should be generated to clear memory instead of a string clear insn | |
6125 | or a library call. Increasing the value will always make code faster, but | |
6126 | eventually incurs high cost in increased code size. | |
6127 | ||
6128 | If you don't define this, a reasonable default is used. | |
a2c4f8e0 | 6129 | @end defmac |
78762e3b | 6130 | |
a2c4f8e0 | 6131 | @defmac CLEAR_BY_PIECES_P (@var{size}, @var{alignment}) |
78762e3b RS |
6132 | A C expression used to determine whether @code{clear_by_pieces} will be used |
6133 | to clear a chunk of memory, or whether some other block clear mechanism | |
6134 | will be used. Defaults to 1 if @code{move_by_pieces_ninsns} returns less | |
6135 | than @code{CLEAR_RATIO}. | |
a2c4f8e0 | 6136 | @end defmac |
78762e3b | 6137 | |
cfa31150 SL |
6138 | @defmac SET_RATIO |
6139 | The threshold of number of scalar move insns, @emph{below} which a sequence | |
6140 | of insns should be generated to set memory to a constant value, instead of | |
6141 | a block set insn or a library call. | |
6142 | Increasing the value will always make code faster, but | |
6143 | eventually incurs high cost in increased code size. | |
6144 | ||
6145 | If you don't define this, it defaults to the value of @code{MOVE_RATIO}. | |
6146 | @end defmac | |
6147 | ||
6148 | @defmac SET_BY_PIECES_P (@var{size}, @var{alignment}) | |
6149 | A C expression used to determine whether @code{store_by_pieces} will be | |
6150 | used to set a chunk of memory to a constant value, or whether some | |
6151 | other mechanism will be used. Used by @code{__builtin_memset} when | |
6152 | storing values other than constant zero. | |
6153 | Defaults to 1 if @code{move_by_pieces_ninsns} returns less | |
6154 | than @code{SET_RATIO}. | |
6155 | @end defmac | |
6156 | ||
a2c4f8e0 | 6157 | @defmac STORE_BY_PIECES_P (@var{size}, @var{alignment}) |
4977bab6 | 6158 | A C expression used to determine whether @code{store_by_pieces} will be |
cfa31150 SL |
6159 | used to set a chunk of memory to a constant string value, or whether some |
6160 | other mechanism will be used. Used by @code{__builtin_strcpy} when | |
6161 | called with a constant source string. | |
0bdcd332 | 6162 | Defaults to 1 if @code{move_by_pieces_ninsns} returns less |
45d78e7f | 6163 | than @code{MOVE_RATIO}. |
a2c4f8e0 | 6164 | @end defmac |
4977bab6 | 6165 | |
a2c4f8e0 | 6166 | @defmac USE_LOAD_POST_INCREMENT (@var{mode}) |
6e01bd94 MH |
6167 | A C expression used to determine whether a load postincrement is a good |
6168 | thing to use for a given mode. Defaults to the value of | |
6169 | @code{HAVE_POST_INCREMENT}. | |
a2c4f8e0 | 6170 | @end defmac |
6e01bd94 | 6171 | |
a2c4f8e0 | 6172 | @defmac USE_LOAD_POST_DECREMENT (@var{mode}) |
6e01bd94 MH |
6173 | A C expression used to determine whether a load postdecrement is a good |
6174 | thing to use for a given mode. Defaults to the value of | |
6175 | @code{HAVE_POST_DECREMENT}. | |
a2c4f8e0 | 6176 | @end defmac |
fbe1758d | 6177 | |
a2c4f8e0 | 6178 | @defmac USE_LOAD_PRE_INCREMENT (@var{mode}) |
6e01bd94 MH |
6179 | A C expression used to determine whether a load preincrement is a good |
6180 | thing to use for a given mode. Defaults to the value of | |
6181 | @code{HAVE_PRE_INCREMENT}. | |
a2c4f8e0 | 6182 | @end defmac |
6e01bd94 | 6183 | |
a2c4f8e0 | 6184 | @defmac USE_LOAD_PRE_DECREMENT (@var{mode}) |
6e01bd94 MH |
6185 | A C expression used to determine whether a load predecrement is a good |
6186 | thing to use for a given mode. Defaults to the value of | |
6187 | @code{HAVE_PRE_DECREMENT}. | |
a2c4f8e0 | 6188 | @end defmac |
fbe1758d | 6189 | |
a2c4f8e0 | 6190 | @defmac USE_STORE_POST_INCREMENT (@var{mode}) |
6e01bd94 MH |
6191 | A C expression used to determine whether a store postincrement is a good |
6192 | thing to use for a given mode. Defaults to the value of | |
6193 | @code{HAVE_POST_INCREMENT}. | |
a2c4f8e0 | 6194 | @end defmac |
6e01bd94 | 6195 | |
a2c4f8e0 | 6196 | @defmac USE_STORE_POST_DECREMENT (@var{mode}) |
c771326b | 6197 | A C expression used to determine whether a store postdecrement is a good |
6e01bd94 MH |
6198 | thing to use for a given mode. Defaults to the value of |
6199 | @code{HAVE_POST_DECREMENT}. | |
a2c4f8e0 | 6200 | @end defmac |
fbe1758d | 6201 | |
a2c4f8e0 | 6202 | @defmac USE_STORE_PRE_INCREMENT (@var{mode}) |
6e01bd94 MH |
6203 | This macro is used to determine whether a store preincrement is a good |
6204 | thing to use for a given mode. Defaults to the value of | |
6205 | @code{HAVE_PRE_INCREMENT}. | |
a2c4f8e0 | 6206 | @end defmac |
6e01bd94 | 6207 | |
a2c4f8e0 | 6208 | @defmac USE_STORE_PRE_DECREMENT (@var{mode}) |
6e01bd94 MH |
6209 | This macro is used to determine whether a store predecrement is a good |
6210 | thing to use for a given mode. Defaults to the value of | |
6211 | @code{HAVE_PRE_DECREMENT}. | |
a2c4f8e0 | 6212 | @end defmac |
fbe1758d | 6213 | |
a2c4f8e0 | 6214 | @defmac NO_FUNCTION_CSE |
feca2ed3 JW |
6215 | Define this macro if it is as good or better to call a constant |
6216 | function address than to call an address kept in a register. | |
a2c4f8e0 | 6217 | @end defmac |
feca2ed3 | 6218 | |
a2c4f8e0 | 6219 | @defmac RANGE_TEST_NON_SHORT_CIRCUIT |
85e50b6b DE |
6220 | Define this macro if a non-short-circuit operation produced by |
6221 | @samp{fold_range_test ()} is optimal. This macro defaults to true if | |
6222 | @code{BRANCH_COST} is greater than or equal to the value 2. | |
a2c4f8e0 | 6223 | @end defmac |
feca2ed3 | 6224 | |
3c50106f RH |
6225 | @deftypefn {Target Hook} bool TARGET_RTX_COSTS (rtx @var{x}, int @var{code}, int @var{outer_code}, int *@var{total}) |
6226 | This target hook describes the relative costs of RTL expressions. | |
6227 | ||
6228 | The cost may depend on the precise form of the expression, which is | |
6229 | available for examination in @var{x}, and the rtx code of the expression | |
6230 | in which it is contained, found in @var{outer_code}. @var{code} is the | |
6231 | expression code---redundant, since it can be obtained with | |
6232 | @code{GET_CODE (@var{x})}. | |
6233 | ||
6234 | In implementing this hook, you can use the construct | |
6235 | @code{COSTS_N_INSNS (@var{n})} to specify a cost equal to @var{n} fast | |
6236 | instructions. | |
6237 | ||
6238 | On entry to the hook, @code{*@var{total}} contains a default estimate | |
6239 | for the cost of the expression. The hook should modify this value as | |
31a52b86 RS |
6240 | necessary. Traditionally, the default costs are @code{COSTS_N_INSNS (5)} |
6241 | for multiplications, @code{COSTS_N_INSNS (7)} for division and modulus | |
6242 | operations, and @code{COSTS_N_INSNS (1)} for all other operations. | |
6243 | ||
8a36672b | 6244 | When optimizing for code size, i.e.@: when @code{optimize_size} is |
1a141fe1 | 6245 | nonzero, this target hook should be used to estimate the relative |
31a52b86 | 6246 | size cost of an expression, again relative to @code{COSTS_N_INSNS}. |
3c50106f RH |
6247 | |
6248 | The hook returns true when all subexpressions of @var{x} have been | |
6249 | processed, and false when @code{rtx_cost} should recurse. | |
6250 | @end deftypefn | |
6251 | ||
10154ff8 RH |
6252 | @deftypefn {Target Hook} int TARGET_ADDRESS_COST (rtx @var{address}) |
6253 | This hook computes the cost of an addressing mode that contains | |
6254 | @var{address}. If not defined, the cost is computed from | |
6255 | the @var{address} expression and the @code{TARGET_RTX_COST} hook. | |
6256 | ||
6257 | For most CISC machines, the default cost is a good approximation of the | |
6258 | true cost of the addressing mode. However, on RISC machines, all | |
6259 | instructions normally have the same length and execution time. Hence | |
6260 | all addresses will have equal costs. | |
6261 | ||
6262 | In cases where more than one form of an address is known, the form with | |
6263 | the lowest cost will be used. If multiple forms have the same, lowest, | |
6264 | cost, the one that is the most complex will be used. | |
6265 | ||
6266 | For example, suppose an address that is equal to the sum of a register | |
6267 | and a constant is used twice in the same basic block. When this macro | |
6268 | is not defined, the address will be computed in a register and memory | |
6269 | references will be indirect through that register. On machines where | |
6270 | the cost of the addressing mode containing the sum is no higher than | |
6271 | that of a simple indirect reference, this will produce an additional | |
6272 | instruction and possibly require an additional register. Proper | |
6273 | specification of this macro eliminates this overhead for such machines. | |
6274 | ||
6275 | This hook is never called with an invalid address. | |
6276 | ||
6277 | On machines where an address involving more than one register is as | |
6278 | cheap as an address computation involving only one register, defining | |
6279 | @code{TARGET_ADDRESS_COST} to reflect this can cause two registers to | |
6280 | be live over a region of code where only one would have been if | |
6281 | @code{TARGET_ADDRESS_COST} were not defined in that manner. This effect | |
6282 | should be considered in the definition of this macro. Equivalent costs | |
6283 | should probably only be given to addresses with different numbers of | |
6284 | registers on machines with lots of registers. | |
6285 | @end deftypefn | |
6286 | ||
c237e94a ZW |
6287 | @node Scheduling |
6288 | @section Adjusting the Instruction Scheduler | |
6289 | ||
6290 | The instruction scheduler may need a fair amount of machine-specific | |
6291 | adjustment in order to produce good code. GCC provides several target | |
6292 | hooks for this purpose. It is usually enough to define just a few of | |
6293 | them: try the first ones in this list first. | |
6294 | ||
6295 | @deftypefn {Target Hook} int TARGET_SCHED_ISSUE_RATE (void) | |
fae15c93 VM |
6296 | This hook returns the maximum number of instructions that can ever |
6297 | issue at the same time on the target machine. The default is one. | |
6298 | Although the insn scheduler can define itself the possibility of issue | |
6299 | an insn on the same cycle, the value can serve as an additional | |
6300 | constraint to issue insns on the same simulated processor cycle (see | |
6301 | hooks @samp{TARGET_SCHED_REORDER} and @samp{TARGET_SCHED_REORDER2}). | |
6302 | This value must be constant over the entire compilation. If you need | |
6303 | it to vary depending on what the instructions are, you must use | |
c237e94a ZW |
6304 | @samp{TARGET_SCHED_VARIABLE_ISSUE}. |
6305 | @end deftypefn | |
6306 | ||
6307 | @deftypefn {Target Hook} int TARGET_SCHED_VARIABLE_ISSUE (FILE *@var{file}, int @var{verbose}, rtx @var{insn}, int @var{more}) | |
6308 | This hook is executed by the scheduler after it has scheduled an insn | |
6309 | from the ready list. It should return the number of insns which can | |
3ee04299 DE |
6310 | still be issued in the current cycle. The default is |
6311 | @samp{@w{@var{more} - 1}} for insns other than @code{CLOBBER} and | |
6312 | @code{USE}, which normally are not counted against the issue rate. | |
6313 | You should define this hook if some insns take more machine resources | |
6314 | than others, so that fewer insns can follow them in the same cycle. | |
6315 | @var{file} is either a null pointer, or a stdio stream to write any | |
6316 | debug output to. @var{verbose} is the verbose level provided by | |
6317 | @option{-fsched-verbose-@var{n}}. @var{insn} is the instruction that | |
6318 | was scheduled. | |
c237e94a ZW |
6319 | @end deftypefn |
6320 | ||
6321 | @deftypefn {Target Hook} int TARGET_SCHED_ADJUST_COST (rtx @var{insn}, rtx @var{link}, rtx @var{dep_insn}, int @var{cost}) | |
fae15c93 VM |
6322 | This function corrects the value of @var{cost} based on the |
6323 | relationship between @var{insn} and @var{dep_insn} through the | |
6324 | dependence @var{link}. It should return the new value. The default | |
6325 | is to make no adjustment to @var{cost}. This can be used for example | |
6326 | to specify to the scheduler using the traditional pipeline description | |
c237e94a | 6327 | that an output- or anti-dependence does not incur the same cost as a |
fae15c93 VM |
6328 | data-dependence. If the scheduler using the automaton based pipeline |
6329 | description, the cost of anti-dependence is zero and the cost of | |
6330 | output-dependence is maximum of one and the difference of latency | |
6331 | times of the first and the second insns. If these values are not | |
6332 | acceptable, you could use the hook to modify them too. See also | |
fa0aee89 | 6333 | @pxref{Processor pipeline description}. |
c237e94a ZW |
6334 | @end deftypefn |
6335 | ||
6336 | @deftypefn {Target Hook} int TARGET_SCHED_ADJUST_PRIORITY (rtx @var{insn}, int @var{priority}) | |
6337 | This hook adjusts the integer scheduling priority @var{priority} of | |
496d7bb0 MK |
6338 | @var{insn}. It should return the new priority. Increase the priority to |
6339 | execute @var{insn} earlier, reduce the priority to execute @var{insn} | |
c237e94a ZW |
6340 | later. Do not define this hook if you do not need to adjust the |
6341 | scheduling priorities of insns. | |
6342 | @end deftypefn | |
6343 | ||
6344 | @deftypefn {Target Hook} int TARGET_SCHED_REORDER (FILE *@var{file}, int @var{verbose}, rtx *@var{ready}, int *@var{n_readyp}, int @var{clock}) | |
6345 | This hook is executed by the scheduler after it has scheduled the ready | |
6346 | list, to allow the machine description to reorder it (for example to | |
6347 | combine two small instructions together on @samp{VLIW} machines). | |
6348 | @var{file} is either a null pointer, or a stdio stream to write any | |
6349 | debug output to. @var{verbose} is the verbose level provided by | |
6350 | @option{-fsched-verbose-@var{n}}. @var{ready} is a pointer to the ready | |
6351 | list of instructions that are ready to be scheduled. @var{n_readyp} is | |
6352 | a pointer to the number of elements in the ready list. The scheduler | |
6353 | reads the ready list in reverse order, starting with | |
6354 | @var{ready}[@var{*n_readyp}-1] and going to @var{ready}[0]. @var{clock} | |
6355 | is the timer tick of the scheduler. You may modify the ready list and | |
6356 | the number of ready insns. The return value is the number of insns that | |
6357 | can issue this cycle; normally this is just @code{issue_rate}. See also | |
6358 | @samp{TARGET_SCHED_REORDER2}. | |
6359 | @end deftypefn | |
6360 | ||
6361 | @deftypefn {Target Hook} int TARGET_SCHED_REORDER2 (FILE *@var{file}, int @var{verbose}, rtx *@var{ready}, int *@var{n_ready}, @var{clock}) | |
6362 | Like @samp{TARGET_SCHED_REORDER}, but called at a different time. That | |
6363 | function is called whenever the scheduler starts a new cycle. This one | |
6364 | is called once per iteration over a cycle, immediately after | |
6365 | @samp{TARGET_SCHED_VARIABLE_ISSUE}; it can reorder the ready list and | |
6366 | return the number of insns to be scheduled in the same cycle. Defining | |
6367 | this hook can be useful if there are frequent situations where | |
6368 | scheduling one insn causes other insns to become ready in the same | |
6369 | cycle. These other insns can then be taken into account properly. | |
6370 | @end deftypefn | |
6371 | ||
30028c85 VM |
6372 | @deftypefn {Target Hook} void TARGET_SCHED_DEPENDENCIES_EVALUATION_HOOK (rtx @var{head}, rtx @var{tail}) |
6373 | This hook is called after evaluation forward dependencies of insns in | |
6374 | chain given by two parameter values (@var{head} and @var{tail} | |
6375 | correspondingly) but before insns scheduling of the insn chain. For | |
6376 | example, it can be used for better insn classification if it requires | |
6377 | analysis of dependencies. This hook can use backward and forward | |
6378 | dependencies of the insn scheduler because they are already | |
6379 | calculated. | |
6380 | @end deftypefn | |
6381 | ||
c237e94a ZW |
6382 | @deftypefn {Target Hook} void TARGET_SCHED_INIT (FILE *@var{file}, int @var{verbose}, int @var{max_ready}) |
6383 | This hook is executed by the scheduler at the beginning of each block of | |
6384 | instructions that are to be scheduled. @var{file} is either a null | |
6385 | pointer, or a stdio stream to write any debug output to. @var{verbose} | |
6386 | is the verbose level provided by @option{-fsched-verbose-@var{n}}. | |
6387 | @var{max_ready} is the maximum number of insns in the current scheduling | |
6388 | region that can be live at the same time. This can be used to allocate | |
431ae0bf | 6389 | scratch space if it is needed, e.g.@: by @samp{TARGET_SCHED_REORDER}. |
c237e94a ZW |
6390 | @end deftypefn |
6391 | ||
6392 | @deftypefn {Target Hook} void TARGET_SCHED_FINISH (FILE *@var{file}, int @var{verbose}) | |
6393 | This hook is executed by the scheduler at the end of each block of | |
6394 | instructions that are to be scheduled. It can be used to perform | |
6395 | cleanup of any actions done by the other scheduling hooks. @var{file} | |
6396 | is either a null pointer, or a stdio stream to write any debug output | |
6397 | to. @var{verbose} is the verbose level provided by | |
6398 | @option{-fsched-verbose-@var{n}}. | |
6399 | @end deftypefn | |
6400 | ||
58565a33 SKG |
6401 | @deftypefn {Target Hook} void TARGET_SCHED_INIT_GLOBAL (FILE *@var{file}, int @var{verbose}, int @var{old_max_uid}) |
6402 | This hook is executed by the scheduler after function level initializations. | |
6403 | @var{file} is either a null pointer, or a stdio stream to write any debug output to. | |
6404 | @var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}. | |
6405 | @var{old_max_uid} is the maximum insn uid when scheduling begins. | |
6406 | @end deftypefn | |
6407 | ||
6408 | @deftypefn {Target Hook} void TARGET_SCHED_FINISH_GLOBAL (FILE *@var{file}, int @var{verbose}) | |
8a36672b | 6409 | This is the cleanup hook corresponding to @code{TARGET_SCHED_INIT_GLOBAL}. |
58565a33 SKG |
6410 | @var{file} is either a null pointer, or a stdio stream to write any debug output to. |
6411 | @var{verbose} is the verbose level provided by @option{-fsched-verbose-@var{n}}. | |
6412 | @end deftypefn | |
6413 | ||
fae15c93 VM |
6414 | @deftypefn {Target Hook} int TARGET_SCHED_DFA_PRE_CYCLE_INSN (void) |
6415 | The hook returns an RTL insn. The automaton state used in the | |
6416 | pipeline hazard recognizer is changed as if the insn were scheduled | |
6417 | when the new simulated processor cycle starts. Usage of the hook may | |
6418 | simplify the automaton pipeline description for some @acronym{VLIW} | |
6419 | processors. If the hook is defined, it is used only for the automaton | |
6420 | based pipeline description. The default is not to change the state | |
6421 | when the new simulated processor cycle starts. | |
6422 | @end deftypefn | |
6423 | ||
6424 | @deftypefn {Target Hook} void TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN (void) | |
6425 | The hook can be used to initialize data used by the previous hook. | |
6426 | @end deftypefn | |
6427 | ||
6428 | @deftypefn {Target Hook} int TARGET_SCHED_DFA_POST_CYCLE_INSN (void) | |
6429 | The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used | |
6430 | to changed the state as if the insn were scheduled when the new | |
6431 | simulated processor cycle finishes. | |
6432 | @end deftypefn | |
6433 | ||
6434 | @deftypefn {Target Hook} void TARGET_SCHED_INIT_DFA_POST_CYCLE_INSN (void) | |
6435 | The hook is analogous to @samp{TARGET_SCHED_INIT_DFA_PRE_CYCLE_INSN} but | |
6436 | used to initialize data used by the previous hook. | |
6437 | @end deftypefn | |
6438 | ||
1c3d0d93 MK |
6439 | @deftypefn {Target Hook} void TARGET_SCHED_DFA_PRE_CYCLE_ADVANCE (void) |
6440 | The hook to notify target that the current simulated cycle is about to finish. | |
6441 | The hook is analogous to @samp{TARGET_SCHED_DFA_PRE_CYCLE_INSN} but used | |
021efafc | 6442 | to change the state in more complicated situations - e.g., when advancing |
1c3d0d93 MK |
6443 | state on a single insn is not enough. |
6444 | @end deftypefn | |
6445 | ||
6446 | @deftypefn {Target Hook} void TARGET_SCHED_DFA_POST_CYCLE_ADVANCE (void) | |
6447 | The hook to notify target that new simulated cycle has just started. | |
6448 | The hook is analogous to @samp{TARGET_SCHED_DFA_POST_CYCLE_INSN} but used | |
021efafc | 6449 | to change the state in more complicated situations - e.g., when advancing |
1c3d0d93 MK |
6450 | state on a single insn is not enough. |
6451 | @end deftypefn | |
6452 | ||
fae15c93 VM |
6453 | @deftypefn {Target Hook} int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD (void) |
6454 | This hook controls better choosing an insn from the ready insn queue | |
6455 | for the @acronym{DFA}-based insn scheduler. Usually the scheduler | |
6456 | chooses the first insn from the queue. If the hook returns a positive | |
6457 | value, an additional scheduler code tries all permutations of | |
6458 | @samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD ()} | |
6459 | subsequent ready insns to choose an insn whose issue will result in | |
6460 | maximal number of issued insns on the same cycle. For the | |
6461 | @acronym{VLIW} processor, the code could actually solve the problem of | |
6462 | packing simple insns into the @acronym{VLIW} insn. Of course, if the | |
6463 | rules of @acronym{VLIW} packing are described in the automaton. | |
6464 | ||
6465 | This code also could be used for superscalar @acronym{RISC} | |
6466 | processors. Let us consider a superscalar @acronym{RISC} processor | |
6467 | with 3 pipelines. Some insns can be executed in pipelines @var{A} or | |
6468 | @var{B}, some insns can be executed only in pipelines @var{B} or | |
6469 | @var{C}, and one insn can be executed in pipeline @var{B}. The | |
6470 | processor may issue the 1st insn into @var{A} and the 2nd one into | |
6471 | @var{B}. In this case, the 3rd insn will wait for freeing @var{B} | |
6472 | until the next cycle. If the scheduler issues the 3rd insn the first, | |
6473 | the processor could issue all 3 insns per cycle. | |
6474 | ||
6475 | Actually this code demonstrates advantages of the automaton based | |
6476 | pipeline hazard recognizer. We try quickly and easy many insn | |
6477 | schedules to choose the best one. | |
6478 | ||
6479 | The default is no multipass scheduling. | |
6480 | @end deftypefn | |
6481 | ||
30028c85 VM |
6482 | @deftypefn {Target Hook} int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD (rtx) |
6483 | ||
6484 | This hook controls what insns from the ready insn queue will be | |
6485 | considered for the multipass insn scheduling. If the hook returns | |
6486 | zero for insn passed as the parameter, the insn will be not chosen to | |
6487 | be issued. | |
6488 | ||
62b9c42c | 6489 | The default is that any ready insns can be chosen to be issued. |
30028c85 VM |
6490 | @end deftypefn |
6491 | ||
6492 | @deftypefn {Target Hook} int TARGET_SCHED_DFA_NEW_CYCLE (FILE *, int, rtx, int, int, int *) | |
6493 | ||
6494 | This hook is called by the insn scheduler before issuing insn passed | |
6495 | as the third parameter on given cycle. If the hook returns nonzero, | |
6496 | the insn is not issued on given processors cycle. Instead of that, | |
6497 | the processor cycle is advanced. If the value passed through the last | |
6498 | parameter is zero, the insn ready queue is not sorted on the new cycle | |
6499 | start as usually. The first parameter passes file for debugging | |
6500 | output. The second one passes the scheduler verbose level of the | |
6501 | debugging output. The forth and the fifth parameter values are | |
6502 | correspondingly processor cycle on which the previous insn has been | |
6503 | issued and the current processor cycle. | |
6504 | @end deftypefn | |
6505 | ||
b198261f | 6506 | @deftypefn {Target Hook} bool TARGET_SCHED_IS_COSTLY_DEPENDENCE (struct dep_def *@var{_dep}, int @var{cost}, int @var{distance}) |
569fa502 | 6507 | This hook is used to define which dependences are considered costly by |
daf2f129 | 6508 | the target, so costly that it is not advisable to schedule the insns that |
569fa502 | 6509 | are involved in the dependence too close to one another. The parameters |
b198261f MK |
6510 | to this hook are as follows: The first parameter @var{_dep} is the dependence |
6511 | being evaluated. The second parameter @var{cost} is the cost of the | |
6512 | dependence, and the third | |
daf2f129 | 6513 | parameter @var{distance} is the distance in cycles between the two insns. |
569fa502 DN |
6514 | The hook returns @code{true} if considering the distance between the two |
6515 | insns the dependence between them is considered costly by the target, | |
6516 | and @code{false} otherwise. | |
6517 | ||
6518 | Defining this hook can be useful in multiple-issue out-of-order machines, | |
daf2f129 | 6519 | where (a) it's practically hopeless to predict the actual data/resource |
569fa502 | 6520 | delays, however: (b) there's a better chance to predict the actual grouping |
daf2f129 | 6521 | that will be formed, and (c) correctly emulating the grouping can be very |
569fa502 | 6522 | important. In such targets one may want to allow issuing dependent insns |
78466c0e | 6523 | closer to one another---i.e., closer than the dependence distance; however, |
569fa502 DN |
6524 | not in cases of "costly dependences", which this hooks allows to define. |
6525 | @end deftypefn | |
6526 | ||
496d7bb0 MK |
6527 | @deftypefn {Target Hook} void TARGET_SCHED_H_I_D_EXTENDED (void) |
6528 | This hook is called by the insn scheduler after emitting a new instruction to | |
6529 | the instruction stream. The hook notifies a target backend to extend its | |
6530 | per instruction data structures. | |
6531 | @end deftypefn | |
6532 | ||
e855c69d AB |
6533 | @deftypefn {Target Hook} void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void) |
6534 | Return a pointer to a store large enough to hold target scheduling context. | |
6535 | @end deftypefn | |
6536 | ||
6537 | @deftypefn {Target Hook} void TARGET_SCHED_INIT_SCHED_CONTEXT (void *@var{tc}, bool @var{clean_p}) | |
6538 | Initialize store pointed to by @var{tc} to hold target scheduling context. | |
6539 | It @var{clean_p} is true then initialize @var{tc} as if scheduler is at the | |
a640c13b | 6540 | beginning of the block. Otherwise, make a copy of the current context in |
e855c69d AB |
6541 | @var{tc}. |
6542 | @end deftypefn | |
6543 | ||
6544 | @deftypefn {Target Hook} void TARGET_SCHED_SET_SCHED_CONTEXT (void *@var{tc}) | |
6545 | Copy target scheduling context pointer to by @var{tc} to the current context. | |
388092d5 AB |
6546 | @end deftypefn |
6547 | ||
6548 | @deftypefn {Target Hook} void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *@var{tc}) | |
6549 | Deallocate internal data in target scheduling context pointed to by @var{tc}. | |
6550 | @end deftypefn | |
6551 | ||
6552 | @deftypefn {Target Hook} void TARGET_SCHED_FREE_SCHED_CONTEXT (void *@var{tc}) | |
6553 | Deallocate a store for target scheduling context pointed to by @var{tc}. | |
6554 | @end deftypefn | |
6555 | ||
6556 | @deftypefn {Target Hook} void * TARGET_SCHED_ALLOC_SCHED_CONTEXT (void) | |
6557 | Return a pointer to a store large enough to hold target scheduling context. | |
6558 | @end deftypefn | |
6559 | ||
6560 | @deftypefn {Target Hook} void TARGET_SCHED_INIT_SCHED_CONTEXT (void *@var{tc}, bool @var{clean_p}) | |
6561 | Initialize store pointed to by @var{tc} to hold target scheduling context. | |
6562 | It @var{clean_p} is true then initialize @var{tc} as if scheduler is at the | |
a640c13b | 6563 | beginning of the block. Otherwise, make a copy of the current context in |
388092d5 AB |
6564 | @var{tc}. |
6565 | @end deftypefn | |
6566 | ||
6567 | @deftypefn {Target Hook} void TARGET_SCHED_SET_SCHED_CONTEXT (void *@var{tc}) | |
6568 | Copy target scheduling context pointer to by @var{tc} to the current context. | |
e855c69d AB |
6569 | @end deftypefn |
6570 | ||
6571 | @deftypefn {Target Hook} void TARGET_SCHED_CLEAR_SCHED_CONTEXT (void *@var{tc}) | |
6572 | Deallocate internal data in target scheduling context pointed to by @var{tc}. | |
6573 | @end deftypefn | |
6574 | ||
6575 | @deftypefn {Target Hook} void TARGET_SCHED_FREE_SCHED_CONTEXT (void *@var{tc}) | |
6576 | Deallocate a store for target scheduling context pointed to by @var{tc}. | |
6577 | @end deftypefn | |
6578 | ||
496d7bb0 | 6579 | @deftypefn {Target Hook} int TARGET_SCHED_SPECULATE_INSN (rtx @var{insn}, int @var{request}, rtx *@var{new_pat}) |
64ee9490 EC |
6580 | This hook is called by the insn scheduler when @var{insn} has only |
6581 | speculative dependencies and therefore can be scheduled speculatively. | |
6582 | The hook is used to check if the pattern of @var{insn} has a speculative | |
6583 | version and, in case of successful check, to generate that speculative | |
6584 | pattern. The hook should return 1, if the instruction has a speculative form, | |
6585 | or -1, if it doesn't. @var{request} describes the type of requested | |
496d7bb0 MK |
6586 | speculation. If the return value equals 1 then @var{new_pat} is assigned |
6587 | the generated speculative pattern. | |
6588 | @end deftypefn | |
6589 | ||
6590 | @deftypefn {Target Hook} int TARGET_SCHED_NEEDS_BLOCK_P (rtx @var{insn}) | |
6591 | This hook is called by the insn scheduler during generation of recovery code | |
917f1b7e | 6592 | for @var{insn}. It should return nonzero, if the corresponding check |
496d7bb0 MK |
6593 | instruction should branch to recovery code, or zero otherwise. |
6594 | @end deftypefn | |
6595 | ||
6596 | @deftypefn {Target Hook} rtx TARGET_SCHED_GEN_CHECK (rtx @var{insn}, rtx @var{label}, int @var{mutate_p}) | |
6597 | This hook is called by the insn scheduler to generate a pattern for recovery | |
64ee9490 EC |
6598 | check instruction. If @var{mutate_p} is zero, then @var{insn} is a |
6599 | speculative instruction for which the check should be generated. | |
6600 | @var{label} is either a label of a basic block, where recovery code should | |
6601 | be emitted, or a null pointer, when requested check doesn't branch to | |
6602 | recovery code (a simple check). If @var{mutate_p} is nonzero, then | |
6603 | a pattern for a branchy check corresponding to a simple check denoted by | |
496d7bb0 MK |
6604 | @var{insn} should be generated. In this case @var{label} can't be null. |
6605 | @end deftypefn | |
6606 | ||
6607 | @deftypefn {Target Hook} int TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD_SPEC (rtx @var{insn}) | |
6608 | This hook is used as a workaround for | |
6609 | @samp{TARGET_SCHED_FIRST_CYCLE_MULTIPASS_DFA_LOOKAHEAD_GUARD} not being | |
6610 | called on the first instruction of the ready list. The hook is used to | |
6611 | discard speculative instruction that stand first in the ready list from | |
64ee9490 | 6612 | being scheduled on the current cycle. For non-speculative instructions, |
917f1b7e | 6613 | the hook should always return nonzero. For example, in the ia64 backend |
496d7bb0 MK |
6614 | the hook is used to cancel data speculative insns when the ALAT table |
6615 | is nearly full. | |
6616 | @end deftypefn | |
6617 | ||
6618 | @deftypefn {Target Hook} void TARGET_SCHED_SET_SCHED_FLAGS (unsigned int *@var{flags}, spec_info_t @var{spec_info}) | |
64ee9490 | 6619 | This hook is used by the insn scheduler to find out what features should be |
496d7bb0 | 6620 | enabled/used. @var{flags} initially may have either the SCHED_RGN or SCHED_EBB |
64ee9490 | 6621 | bit set. This denotes the scheduler pass for which the data should be |
496d7bb0 | 6622 | provided. The target backend should modify @var{flags} by modifying |
917f1b7e | 6623 | the bits corresponding to the following features: USE_DEPS_LIST, USE_GLAT, |
0ee2ea09 | 6624 | DETACH_LIFE_INFO, and DO_SPECULATION@. For the DO_SPECULATION feature |
64ee9490 | 6625 | an additional structure @var{spec_info} should be filled by the target. |
496d7bb0 MK |
6626 | The structure describes speculation types that can be used in the scheduler. |
6627 | @end deftypefn | |
6628 | ||
67186a97 TS |
6629 | @deftypefn {Target Hook} int TARGET_SCHED_SMS_RES_MII (struct ddg *@var{g}) |
6630 | This hook is called by the swing modulo scheduler to calculate a | |
6631 | resource-based lower bound which is based on the resources available in | |
6632 | the machine and the resources required by each instruction. The target | |
6633 | backend can use @var{g} to calculate such bound. A very simple lower | |
6634 | bound will be used in case this hook is not implemented: the total number | |
6635 | of instructions divided by the issue rate. | |
6636 | @end deftypefn | |
6637 | ||
feca2ed3 JW |
6638 | @node Sections |
6639 | @section Dividing the Output into Sections (Texts, Data, @dots{}) | |
6640 | @c the above section title is WAY too long. maybe cut the part between | |
6641 | @c the (...)? --mew 10feb93 | |
6642 | ||
6643 | An object file is divided into sections containing different types of | |
6644 | data. In the most common case, there are three sections: the @dfn{text | |
6645 | section}, which holds instructions and read-only data; the @dfn{data | |
6646 | section}, which holds initialized writable data; and the @dfn{bss | |
6647 | section}, which holds uninitialized data. Some systems have other kinds | |
6648 | of sections. | |
6649 | ||
d6b5193b RS |
6650 | @file{varasm.c} provides several well-known sections, such as |
6651 | @code{text_section}, @code{data_section} and @code{bss_section}. | |
6652 | The normal way of controlling a @code{@var{foo}_section} variable | |
6653 | is to define the associated @code{@var{FOO}_SECTION_ASM_OP} macro, | |
6654 | as described below. The macros are only read once, when @file{varasm.c} | |
6655 | initializes itself, so their values must be run-time constants. | |
6656 | They may however depend on command-line flags. | |
6657 | ||
6658 | @emph{Note:} Some run-time files, such @file{crtstuff.c}, also make | |
6659 | use of the @code{@var{FOO}_SECTION_ASM_OP} macros, and expect them | |
6660 | to be string literals. | |
6661 | ||
6662 | Some assemblers require a different string to be written every time a | |
6663 | section is selected. If your assembler falls into this category, you | |
6664 | should define the @code{TARGET_ASM_INIT_SECTIONS} hook and use | |
6665 | @code{get_unnamed_section} to set up the sections. | |
6666 | ||
6667 | You must always create a @code{text_section}, either by defining | |
6668 | @code{TEXT_SECTION_ASM_OP} or by initializing @code{text_section} | |
6669 | in @code{TARGET_ASM_INIT_SECTIONS}. The same is true of | |
6670 | @code{data_section} and @code{DATA_SECTION_ASM_OP}. If you do not | |
6671 | create a distinct @code{readonly_data_section}, the default is to | |
6672 | reuse @code{text_section}. | |
6673 | ||
6674 | All the other @file{varasm.c} sections are optional, and are null | |
6675 | if the target does not provide them. | |
feca2ed3 | 6676 | |
a2c4f8e0 | 6677 | @defmac TEXT_SECTION_ASM_OP |
047c1c92 HPN |
6678 | A C expression whose value is a string, including spacing, containing the |
6679 | assembler operation that should precede instructions and read-only data. | |
6680 | Normally @code{"\t.text"} is right. | |
a2c4f8e0 | 6681 | @end defmac |
33c09f2f | 6682 | |
a2c4f8e0 | 6683 | @defmac HOT_TEXT_SECTION_NAME |
194734e9 JH |
6684 | If defined, a C string constant for the name of the section containing most |
6685 | frequently executed functions of the program. If not defined, GCC will provide | |
6686 | a default definition if the target supports named sections. | |
a2c4f8e0 | 6687 | @end defmac |
194734e9 | 6688 | |
a2c4f8e0 | 6689 | @defmac UNLIKELY_EXECUTED_TEXT_SECTION_NAME |
194734e9 JH |
6690 | If defined, a C string constant for the name of the section containing unlikely |
6691 | executed functions in the program. | |
a2c4f8e0 | 6692 | @end defmac |
194734e9 | 6693 | |
a2c4f8e0 | 6694 | @defmac DATA_SECTION_ASM_OP |
047c1c92 HPN |
6695 | A C expression whose value is a string, including spacing, containing the |
6696 | assembler operation to identify the following data as writable initialized | |
6697 | data. Normally @code{"\t.data"} is right. | |
a2c4f8e0 | 6698 | @end defmac |
feca2ed3 | 6699 | |
d6b5193b RS |
6700 | @defmac SDATA_SECTION_ASM_OP |
6701 | If defined, a C expression whose value is a string, including spacing, | |
6702 | containing the assembler operation to identify the following data as | |
6703 | initialized, writable small data. | |
6704 | @end defmac | |
6705 | ||
a2c4f8e0 | 6706 | @defmac READONLY_DATA_SECTION_ASM_OP |
d48bc59a RH |
6707 | A C expression whose value is a string, including spacing, containing the |
6708 | assembler operation to identify the following data as read-only initialized | |
6709 | data. | |
a2c4f8e0 | 6710 | @end defmac |
d48bc59a | 6711 | |
a2c4f8e0 | 6712 | @defmac BSS_SECTION_ASM_OP |
047c1c92 HPN |
6713 | If defined, a C expression whose value is a string, including spacing, |
6714 | containing the assembler operation to identify the following data as | |
6715 | uninitialized global data. If not defined, and neither | |
6716 | @code{ASM_OUTPUT_BSS} nor @code{ASM_OUTPUT_ALIGNED_BSS} are defined, | |
6717 | uninitialized global data will be output in the data section if | |
630d3d5a | 6718 | @option{-fno-common} is passed, otherwise @code{ASM_OUTPUT_COMMON} will be |
047c1c92 | 6719 | used. |
a2c4f8e0 | 6720 | @end defmac |
feca2ed3 | 6721 | |
d6b5193b RS |
6722 | @defmac SBSS_SECTION_ASM_OP |
6723 | If defined, a C expression whose value is a string, including spacing, | |
6724 | containing the assembler operation to identify the following data as | |
6725 | uninitialized, writable small data. | |
6726 | @end defmac | |
6727 | ||
a2c4f8e0 | 6728 | @defmac INIT_SECTION_ASM_OP |
047c1c92 HPN |
6729 | If defined, a C expression whose value is a string, including spacing, |
6730 | containing the assembler operation to identify the following data as | |
6731 | initialization code. If not defined, GCC will assume such a section does | |
98bfa2fb RS |
6732 | not exist. This section has no corresponding @code{init_section} |
6733 | variable; it is used entirely in runtime code. | |
a2c4f8e0 | 6734 | @end defmac |
feca2ed3 | 6735 | |
a2c4f8e0 | 6736 | @defmac FINI_SECTION_ASM_OP |
047c1c92 HPN |
6737 | If defined, a C expression whose value is a string, including spacing, |
6738 | containing the assembler operation to identify the following data as | |
6739 | finalization code. If not defined, GCC will assume such a section does | |
98bfa2fb RS |
6740 | not exist. This section has no corresponding @code{fini_section} |
6741 | variable; it is used entirely in runtime code. | |
a2c4f8e0 | 6742 | @end defmac |
750054a2 | 6743 | |
7abc66b1 JB |
6744 | @defmac INIT_ARRAY_SECTION_ASM_OP |
6745 | If defined, a C expression whose value is a string, including spacing, | |
6746 | containing the assembler operation to identify the following data as | |
6747 | part of the @code{.init_array} (or equivalent) section. If not | |
6748 | defined, GCC will assume such a section does not exist. Do not define | |
6749 | both this macro and @code{INIT_SECTION_ASM_OP}. | |
6750 | @end defmac | |
083cad55 | 6751 | |
7abc66b1 JB |
6752 | @defmac FINI_ARRAY_SECTION_ASM_OP |
6753 | If defined, a C expression whose value is a string, including spacing, | |
6754 | containing the assembler operation to identify the following data as | |
6755 | part of the @code{.fini_array} (or equivalent) section. If not | |
6756 | defined, GCC will assume such a section does not exist. Do not define | |
6757 | both this macro and @code{FINI_SECTION_ASM_OP}. | |
6758 | @end defmac | |
6759 | ||
a2c4f8e0 | 6760 | @defmac CRT_CALL_STATIC_FUNCTION (@var{section_op}, @var{function}) |
cea3bd3e RH |
6761 | If defined, an ASM statement that switches to a different section |
6762 | via @var{section_op}, calls @var{function}, and switches back to | |
6763 | the text section. This is used in @file{crtstuff.c} if | |
6764 | @code{INIT_SECTION_ASM_OP} or @code{FINI_SECTION_ASM_OP} to calls | |
6765 | to initialization and finalization functions from the init and fini | |
6766 | sections. By default, this macro uses a simple function call. Some | |
1b2dd04a AO |
6767 | ports need hand-crafted assembly code to avoid dependencies on |
6768 | registers initialized in the function prologue or to ensure that | |
6769 | constant pools don't end up too far way in the text section. | |
a2c4f8e0 | 6770 | @end defmac |
1b2dd04a | 6771 | |
a0cfeb0f DD |
6772 | @defmac TARGET_LIBGCC_SDATA_SECTION |
6773 | If defined, a string which names the section into which small | |
6774 | variables defined in crtstuff and libgcc should go. This is useful | |
6775 | when the target has options for optimizing access to small data, and | |
6776 | you want the crtstuff and libgcc routines to be conservative in what | |
6777 | they expect of your application yet liberal in what your application | |
6778 | expects. For example, for targets with a @code{.sdata} section (like | |
6779 | MIPS), you could compile crtstuff with @code{-G 0} so that it doesn't | |
6780 | require small data support from your application, but use this macro | |
6781 | to put small data into @code{.sdata} so that your application can | |
6782 | access these variables whether it uses small data or not. | |
726e9992 | 6783 | @end defmac |
a0cfeb0f | 6784 | |
a2c4f8e0 | 6785 | @defmac FORCE_CODE_SECTION_ALIGN |
cea3bd3e RH |
6786 | If defined, an ASM statement that aligns a code section to some |
6787 | arbitrary boundary. This is used to force all fragments of the | |
6788 | @code{.init} and @code{.fini} sections to have to same alignment | |
6789 | and thus prevent the linker from having to add any padding. | |
a2c4f8e0 | 6790 | @end defmac |
cea3bd3e | 6791 | |
a2c4f8e0 | 6792 | @defmac JUMP_TABLES_IN_TEXT_SECTION |
df2a54e9 | 6793 | Define this macro to be an expression with a nonzero value if jump |
75197b37 BS |
6794 | tables (for @code{tablejump} insns) should be output in the text |
6795 | section, along with the assembler instructions. Otherwise, the | |
6796 | readonly data section is used. | |
feca2ed3 JW |
6797 | |
6798 | This macro is irrelevant if there is no separate readonly data section. | |
a2c4f8e0 | 6799 | @end defmac |
feca2ed3 | 6800 | |
d6b5193b RS |
6801 | @deftypefn {Target Hook} void TARGET_ASM_INIT_SECTIONS (void) |
6802 | Define this hook if you need to do something special to set up the | |
6803 | @file{varasm.c} sections, or if your target has some special sections | |
6804 | of its own that you need to create. | |
6805 | ||
6806 | GCC calls this hook after processing the command line, but before writing | |
6807 | any assembly code, and before calling any of the section-returning hooks | |
6808 | described below. | |
6809 | @end deftypefn | |
6810 | ||
9b580a0b RH |
6811 | @deftypefn {Target Hook} TARGET_ASM_RELOC_RW_MASK (void) |
6812 | Return a mask describing how relocations should be treated when | |
6813 | selecting sections. Bit 1 should be set if global relocations | |
6814 | should be placed in a read-write section; bit 0 should be set if | |
6815 | local relocations should be placed in a read-write section. | |
6816 | ||
6817 | The default version of this function returns 3 when @option{-fpic} | |
6818 | is in effect, and 0 otherwise. The hook is typically redefined | |
6819 | when the target cannot support (some kinds of) dynamic relocations | |
6820 | in read-only sections even in executables. | |
6821 | @end deftypefn | |
6822 | ||
d6b5193b RS |
6823 | @deftypefn {Target Hook} {section *} TARGET_ASM_SELECT_SECTION (tree @var{exp}, int @var{reloc}, unsigned HOST_WIDE_INT @var{align}) |
6824 | Return the section into which @var{exp} should be placed. You can | |
ae46c4e0 RH |
6825 | assume that @var{exp} is either a @code{VAR_DECL} node or a constant of |
6826 | some sort. @var{reloc} indicates whether the initial value of @var{exp} | |
6827 | requires link-time relocations. Bit 0 is set when variable contains | |
6828 | local relocations only, while bit 1 is set for global relocations. | |
d6b5193b | 6829 | @var{align} is the constant alignment in bits. |
ae46c4e0 RH |
6830 | |
6831 | The default version of this function takes care of putting read-only | |
6832 | variables in @code{readonly_data_section}. | |
09afda70 GK |
6833 | |
6834 | See also @var{USE_SELECT_SECTION_FOR_FUNCTIONS}. | |
ae46c4e0 RH |
6835 | @end deftypefn |
6836 | ||
09afda70 GK |
6837 | @defmac USE_SELECT_SECTION_FOR_FUNCTIONS |
6838 | Define this macro if you wish TARGET_ASM_SELECT_SECTION to be called | |
6839 | for @code{FUNCTION_DECL}s as well as for variables and constants. | |
6840 | ||
6841 | In the case of a @code{FUNCTION_DECL}, @var{reloc} will be zero if the | |
6842 | function has been determined to be likely to be called, and nonzero if | |
6843 | it is unlikely to be called. | |
6844 | @end defmac | |
6845 | ||
ae46c4e0 RH |
6846 | @deftypefn {Target Hook} void TARGET_ASM_UNIQUE_SECTION (tree @var{decl}, int @var{reloc}) |
6847 | Build up a unique section name, expressed as a @code{STRING_CST} node, | |
6848 | and assign it to @samp{DECL_SECTION_NAME (@var{decl})}. | |
6849 | As with @code{TARGET_ASM_SELECT_SECTION}, @var{reloc} indicates whether | |
6850 | the initial value of @var{exp} requires link-time relocations. | |
6851 | ||
6852 | The default version of this function appends the symbol name to the | |
6853 | ELF section name that would normally be used for the symbol. For | |
6854 | example, the function @code{foo} would be placed in @code{.text.foo}. | |
6855 | Whatever the actual target object format, this is often good enough. | |
6856 | @end deftypefn | |
6857 | ||
d6b5193b RS |
6858 | @deftypefn {Target Hook} {section *} TARGET_ASM_FUNCTION_RODATA_SECTION (tree @var{decl}) |
6859 | Return the readonly data section associated with | |
ab5c8549 | 6860 | @samp{DECL_SECTION_NAME (@var{decl})}. |
d6b5193b RS |
6861 | The default version of this function selects @code{.gnu.linkonce.r.name} if |
6862 | the function's section is @code{.gnu.linkonce.t.name}, @code{.rodata.name} | |
6863 | if function is in @code{.text.name}, and the normal readonly-data section | |
6864 | otherwise. | |
ab5c8549 JJ |
6865 | @end deftypefn |
6866 | ||
d6b5193b RS |
6867 | @deftypefn {Target Hook} {section *} TARGET_ASM_SELECT_RTX_SECTION (enum machine_mode @var{mode}, rtx @var{x}, unsigned HOST_WIDE_INT @var{align}) |
6868 | Return the section into which a constant @var{x}, of mode @var{mode}, | |
6869 | should be placed. You can assume that @var{x} is some kind of | |
b64a1b53 | 6870 | constant in RTL@. The argument @var{mode} is redundant except in the |
d6b5193b RS |
6871 | case of a @code{const_int} rtx. @var{align} is the constant alignment |
6872 | in bits. | |
b64a1b53 RH |
6873 | |
6874 | The default version of this function takes care of putting symbolic | |
6875 | constants in @code{flag_pic} mode in @code{data_section} and everything | |
6876 | else in @code{readonly_data_section}. | |
6877 | @end deftypefn | |
6878 | ||
5234b8f5 DS |
6879 | @deftypefn {Target Hook} void TARGET_MANGLE_DECL_ASSEMBLER_NAME (tree @var{decl}, tree @var{id}) |
6880 | Define this hook if you need to postprocess the assembler name generated | |
6881 | by target-independent code. The @var{id} provided to this hook will be | |
6882 | the computed name (e.g., the macro @code{DECL_NAME} of the @var{decl} in C, | |
6883 | or the mangled name of the @var{decl} in C++). The return value of the | |
6884 | hook is an @code{IDENTIFIER_NODE} for the appropriate mangled name on | |
6885 | your target system. The default implementation of this hook just | |
6886 | returns the @var{id} provided. | |
6887 | @end deftypefn | |
6888 | ||
c6a2438a | 6889 | @deftypefn {Target Hook} void TARGET_ENCODE_SECTION_INFO (tree @var{decl}, rtx @var{rtl}, int @var{new_decl_p}) |
fb49053f RH |
6890 | Define this hook if references to a symbol or a constant must be |
6891 | treated differently depending on something about the variable or | |
6892 | function named by the symbol (such as what section it is in). | |
6893 | ||
c6a2438a ZW |
6894 | The hook is executed immediately after rtl has been created for |
6895 | @var{decl}, which may be a variable or function declaration or | |
6896 | an entry in the constant pool. In either case, @var{rtl} is the | |
6897 | rtl in question. Do @emph{not} use @code{DECL_RTL (@var{decl})} | |
0864034e | 6898 | in this hook; that field may not have been initialized yet. |
c6a2438a ZW |
6899 | |
6900 | In the case of a constant, it is safe to assume that the rtl is | |
6901 | a @code{mem} whose address is a @code{symbol_ref}. Most decls | |
6902 | will also have this form, but that is not guaranteed. Global | |
6903 | register variables, for instance, will have a @code{reg} for their | |
6904 | rtl. (Normally the right thing to do with such unusual rtl is | |
6905 | leave it alone.) | |
fb49053f RH |
6906 | |
6907 | The @var{new_decl_p} argument will be true if this is the first time | |
c6a2438a | 6908 | that @code{TARGET_ENCODE_SECTION_INFO} has been invoked on this decl. It will |
fb49053f RH |
6909 | be false for subsequent invocations, which will happen for duplicate |
6910 | declarations. Whether or not anything must be done for the duplicate | |
6911 | declaration depends on whether the hook examines @code{DECL_ATTRIBUTES}. | |
c6a2438a | 6912 | @var{new_decl_p} is always true when the hook is called for a constant. |
fb49053f RH |
6913 | |
6914 | @cindex @code{SYMBOL_REF_FLAG}, in @code{TARGET_ENCODE_SECTION_INFO} | |
c6a2438a ZW |
6915 | The usual thing for this hook to do is to record flags in the |
6916 | @code{symbol_ref}, using @code{SYMBOL_REF_FLAG} or @code{SYMBOL_REF_FLAGS}. | |
6917 | Historically, the name string was modified if it was necessary to | |
6918 | encode more than one bit of information, but this practice is now | |
6919 | discouraged; use @code{SYMBOL_REF_FLAGS}. | |
6920 | ||
6921 | The default definition of this hook, @code{default_encode_section_info} | |
6922 | in @file{varasm.c}, sets a number of commonly-useful bits in | |
6923 | @code{SYMBOL_REF_FLAGS}. Check whether the default does what you need | |
6924 | before overriding it. | |
fb49053f RH |
6925 | @end deftypefn |
6926 | ||
772c5265 RH |
6927 | @deftypefn {Target Hook} const char *TARGET_STRIP_NAME_ENCODING (const char *name) |
6928 | Decode @var{name} and return the real name part, sans | |
6929 | the characters that @code{TARGET_ENCODE_SECTION_INFO} | |
6930 | may have added. | |
6931 | @end deftypefn | |
6932 | ||
47754fd5 RH |
6933 | @deftypefn {Target Hook} bool TARGET_IN_SMALL_DATA_P (tree @var{exp}) |
6934 | Returns true if @var{exp} should be placed into a ``small data'' section. | |
6935 | The default version of this hook always returns false. | |
6936 | @end deftypefn | |
6937 | ||
9e3be889 | 6938 | @deftypevr {Target Hook} bool TARGET_HAVE_SRODATA_SECTION |
e2a6476e DE |
6939 | Contains the value true if the target places read-only |
6940 | ``small data'' into a separate section. The default value is false. | |
9e3be889 | 6941 | @end deftypevr |
e2a6476e | 6942 | |
47754fd5 RH |
6943 | @deftypefn {Target Hook} bool TARGET_BINDS_LOCAL_P (tree @var{exp}) |
6944 | Returns true if @var{exp} names an object for which name resolution | |
6945 | rules must resolve to the current ``module'' (dynamic shared library | |
6946 | or executable image). | |
6947 | ||
6948 | The default version of this hook implements the name resolution rules | |
6949 | for ELF, which has a looser model of global name binding than other | |
6950 | currently supported object file formats. | |
6951 | @end deftypefn | |
6952 | ||
9e3be889 | 6953 | @deftypevr {Target Hook} bool TARGET_HAVE_TLS |
e2a6476e DE |
6954 | Contains the value true if the target supports thread-local storage. |
6955 | The default value is false. | |
9e3be889 | 6956 | @end deftypevr |
e2a6476e DE |
6957 | |
6958 | ||
feca2ed3 JW |
6959 | @node PIC |
6960 | @section Position Independent Code | |
6961 | @cindex position independent code | |
6962 | @cindex PIC | |
6963 | ||
6964 | This section describes macros that help implement generation of position | |
6965 | independent code. Simply defining these macros is not enough to | |
c6c3dba9 PB |
6966 | generate valid PIC; you must also add support to the hook |
6967 | @code{TARGET_LEGITIMATE_ADDRESS_P} and to the macro | |
6968 | @code{PRINT_OPERAND_ADDRESS}, as well as @code{LEGITIMIZE_ADDRESS}. You | |
6969 | must modify the definition of @samp{movsi} to do something appropriate | |
6970 | when the source operand contains a symbolic address. You may also | |
6971 | need to alter the handling of switch statements so that they use | |
6972 | relative addresses. | |
6973 | @c i rearranged the order of the macros above to try to force one of | |
feca2ed3 JW |
6974 | @c them to the next line, to eliminate an overfull hbox. --mew 10feb93 |
6975 | ||
a2c4f8e0 | 6976 | @defmac PIC_OFFSET_TABLE_REGNUM |
feca2ed3 JW |
6977 | The register number of the register used to address a table of static |
6978 | data addresses in memory. In some cases this register is defined by a | |
161d7b59 | 6979 | processor's ``application binary interface'' (ABI)@. When this macro |
feca2ed3 JW |
6980 | is defined, RTL is generated for this register once, as with the stack |
6981 | pointer and frame pointer registers. If this macro is not defined, it | |
6982 | is up to the machine-dependent files to allocate such a register (if | |
003b9f78 | 6983 | necessary). Note that this register must be fixed when in use (e.g.@: |
12beba6f | 6984 | when @code{flag_pic} is true). |
a2c4f8e0 | 6985 | @end defmac |
feca2ed3 | 6986 | |
a2c4f8e0 | 6987 | @defmac PIC_OFFSET_TABLE_REG_CALL_CLOBBERED |
feca2ed3 JW |
6988 | Define this macro if the register defined by |
6989 | @code{PIC_OFFSET_TABLE_REGNUM} is clobbered by calls. Do not define | |
ed4db1ee | 6990 | this macro if @code{PIC_OFFSET_TABLE_REGNUM} is not defined. |
a2c4f8e0 | 6991 | @end defmac |
feca2ed3 | 6992 | |
a2c4f8e0 | 6993 | @defmac LEGITIMATE_PIC_OPERAND_P (@var{x}) |
feca2ed3 JW |
6994 | A C expression that is nonzero if @var{x} is a legitimate immediate |
6995 | operand on the target machine when generating position independent code. | |
6996 | You can assume that @var{x} satisfies @code{CONSTANT_P}, so you need not | |
6997 | check this. You can also assume @var{flag_pic} is true, so you need not | |
6998 | check it either. You need not define this macro if all constants | |
6999 | (including @code{SYMBOL_REF}) can be immediate operands when generating | |
7000 | position independent code. | |
a2c4f8e0 | 7001 | @end defmac |
feca2ed3 JW |
7002 | |
7003 | @node Assembler Format | |
7004 | @section Defining the Output Assembler Language | |
7005 | ||
7006 | This section describes macros whose principal purpose is to describe how | |
648c546a | 7007 | to write instructions in assembler language---rather than what the |
feca2ed3 JW |
7008 | instructions do. |
7009 | ||
7010 | @menu | |
7011 | * File Framework:: Structural information for the assembler file. | |
7012 | * Data Output:: Output of constants (numbers, strings, addresses). | |
7013 | * Uninitialized Data:: Output of uninitialized variables. | |
7014 | * Label Output:: Output and generation of labels. | |
7015 | * Initialization:: General principles of initialization | |
6ccde948 | 7016 | and termination routines. |
feca2ed3 | 7017 | * Macros for Initialization:: |
6ccde948 RW |
7018 | Specific macros that control the handling of |
7019 | initialization and termination routines. | |
feca2ed3 JW |
7020 | * Instruction Output:: Output of actual instructions. |
7021 | * Dispatch Tables:: Output of jump tables. | |
7022 | * Exception Region Output:: Output of exception region code. | |
7023 | * Alignment Output:: Pseudo ops for alignment and skipping data. | |
7024 | @end menu | |
7025 | ||
7026 | @node File Framework | |
7027 | @subsection The Overall Framework of an Assembler File | |
7028 | @cindex assembler format | |
7029 | @cindex output of assembler code | |
7030 | ||
7031 | @c prevent bad page break with this line | |
1bc7c5b6 ZW |
7032 | This describes the overall framework of an assembly file. |
7033 | ||
7034 | @deftypefn {Target Hook} void TARGET_ASM_FILE_START () | |
7035 | @findex default_file_start | |
7036 | Output to @code{asm_out_file} any text which the assembler expects to | |
7037 | find at the beginning of a file. The default behavior is controlled | |
7038 | by two flags, documented below. Unless your target's assembler is | |
7039 | quite unusual, if you override the default, you should call | |
7040 | @code{default_file_start} at some point in your target hook. This | |
7041 | lets other target files rely on these variables. | |
7042 | @end deftypefn | |
feca2ed3 | 7043 | |
1bc7c5b6 ZW |
7044 | @deftypevr {Target Hook} bool TARGET_ASM_FILE_START_APP_OFF |
7045 | If this flag is true, the text of the macro @code{ASM_APP_OFF} will be | |
7046 | printed as the very first line in the assembly file, unless | |
7047 | @option{-fverbose-asm} is in effect. (If that macro has been defined | |
7048 | to the empty string, this variable has no effect.) With the normal | |
7049 | definition of @code{ASM_APP_OFF}, the effect is to notify the GNU | |
7050 | assembler that it need not bother stripping comments or extra | |
7051 | whitespace from its input. This allows it to work a bit faster. | |
7052 | ||
7053 | The default is false. You should not set it to true unless you have | |
7054 | verified that your port does not generate any extra whitespace or | |
7055 | comments that will cause GAS to issue errors in NO_APP mode. | |
7056 | @end deftypevr | |
7057 | ||
7058 | @deftypevr {Target Hook} bool TARGET_ASM_FILE_START_FILE_DIRECTIVE | |
7059 | If this flag is true, @code{output_file_directive} will be called | |
7060 | for the primary source file, immediately after printing | |
7061 | @code{ASM_APP_OFF} (if that is enabled). Most ELF assemblers expect | |
7062 | this to be done. The default is false. | |
7063 | @end deftypevr | |
feca2ed3 | 7064 | |
a5fe455b ZW |
7065 | @deftypefn {Target Hook} void TARGET_ASM_FILE_END () |
7066 | Output to @code{asm_out_file} any text which the assembler expects | |
7067 | to find at the end of a file. The default is to output nothing. | |
7068 | @end deftypefn | |
feca2ed3 | 7069 | |
a5fe455b ZW |
7070 | @deftypefun void file_end_indicate_exec_stack () |
7071 | Some systems use a common convention, the @samp{.note.GNU-stack} | |
7072 | special section, to indicate whether or not an object file relies on | |
7073 | the stack being executable. If your system uses this convention, you | |
7074 | should define @code{TARGET_ASM_FILE_END} to this function. If you | |
7075 | need to do other things in that hook, have your hook function call | |
7076 | this function. | |
7077 | @end deftypefun | |
feca2ed3 | 7078 | |
a2c4f8e0 | 7079 | @defmac ASM_COMMENT_START |
feca2ed3 JW |
7080 | A C string constant describing how to begin a comment in the target |
7081 | assembler language. The compiler assumes that the comment will end at | |
7082 | the end of the line. | |
a2c4f8e0 | 7083 | @end defmac |
feca2ed3 | 7084 | |
a2c4f8e0 | 7085 | @defmac ASM_APP_ON |
feca2ed3 JW |
7086 | A C string constant for text to be output before each @code{asm} |
7087 | statement or group of consecutive ones. Normally this is | |
7088 | @code{"#APP"}, which is a comment that has no effect on most | |
7089 | assemblers but tells the GNU assembler that it must check the lines | |
7090 | that follow for all valid assembler constructs. | |
a2c4f8e0 | 7091 | @end defmac |
feca2ed3 | 7092 | |
a2c4f8e0 | 7093 | @defmac ASM_APP_OFF |
feca2ed3 JW |
7094 | A C string constant for text to be output after each @code{asm} |
7095 | statement or group of consecutive ones. Normally this is | |
7096 | @code{"#NO_APP"}, which tells the GNU assembler to resume making the | |
7097 | time-saving assumptions that are valid for ordinary compiler output. | |
a2c4f8e0 | 7098 | @end defmac |
feca2ed3 | 7099 | |
a2c4f8e0 | 7100 | @defmac ASM_OUTPUT_SOURCE_FILENAME (@var{stream}, @var{name}) |
feca2ed3 JW |
7101 | A C statement to output COFF information or DWARF debugging information |
7102 | which indicates that filename @var{name} is the current source file to | |
7103 | the stdio stream @var{stream}. | |
7104 | ||
7105 | This macro need not be defined if the standard form of output | |
7106 | for the file format in use is appropriate. | |
a2c4f8e0 | 7107 | @end defmac |
feca2ed3 | 7108 | |
a2c4f8e0 | 7109 | @defmac OUTPUT_QUOTED_STRING (@var{stream}, @var{string}) |
e9a25f70 JL |
7110 | A C statement to output the string @var{string} to the stdio stream |
7111 | @var{stream}. If you do not call the function @code{output_quoted_string} | |
a3a15b4d | 7112 | in your config files, GCC will only call it to output filenames to |
e9a25f70 JL |
7113 | the assembler source. So you can use it to canonicalize the format |
7114 | of the filename using this macro. | |
a2c4f8e0 | 7115 | @end defmac |
e9a25f70 | 7116 | |
a2c4f8e0 | 7117 | @defmac ASM_OUTPUT_IDENT (@var{stream}, @var{string}) |
feca2ed3 JW |
7118 | A C statement to output something to the assembler file to handle a |
7119 | @samp{#ident} directive containing the text @var{string}. If this | |
7120 | macro is not defined, nothing is output for a @samp{#ident} directive. | |
a2c4f8e0 | 7121 | @end defmac |
feca2ed3 | 7122 | |
7c262518 RH |
7123 | @deftypefn {Target Hook} void TARGET_ASM_NAMED_SECTION (const char *@var{name}, unsigned int @var{flags}, unsigned int @var{align}) |
7124 | Output assembly directives to switch to section @var{name}. The section | |
7125 | should have attributes as specified by @var{flags}, which is a bit mask | |
7126 | of the @code{SECTION_*} flags defined in @file{output.h}. If @var{align} | |
df2a54e9 | 7127 | is nonzero, it contains an alignment in bytes to be used for the section, |
f282ffb3 | 7128 | otherwise some target default should be used. Only targets that must |
7c262518 RH |
7129 | specify an alignment within the section directive need pay attention to |
7130 | @var{align} -- we will still use @code{ASM_OUTPUT_ALIGN}. | |
7131 | @end deftypefn | |
7132 | ||
7133 | @deftypefn {Target Hook} bool TARGET_HAVE_NAMED_SECTIONS | |
7134 | This flag is true if the target supports @code{TARGET_ASM_NAMED_SECTION}. | |
7135 | @end deftypefn | |
7136 | ||
434aeebb RS |
7137 | @anchor{TARGET_HAVE_SWITCHABLE_BSS_SECTIONS} |
7138 | @deftypefn {Target Hook} bool TARGET_HAVE_SWITCHABLE_BSS_SECTIONS | |
7139 | This flag is true if we can create zeroed data by switching to a BSS | |
7140 | section and then using @code{ASM_OUTPUT_SKIP} to allocate the space. | |
7141 | This is true on most ELF targets. | |
7142 | @end deftypefn | |
7143 | ||
7c262518 RH |
7144 | @deftypefn {Target Hook} {unsigned int} TARGET_SECTION_TYPE_FLAGS (tree @var{decl}, const char *@var{name}, int @var{reloc}) |
7145 | Choose a set of section attributes for use by @code{TARGET_ASM_NAMED_SECTION} | |
7146 | based on a variable or function decl, a section name, and whether or not the | |
7147 | declaration's initializer may contain runtime relocations. @var{decl} may be | |
6ccde948 | 7148 | null, in which case read-write data should be assumed. |
7c262518 | 7149 | |
224504d2 | 7150 | The default version of this function handles choosing code vs data, |
7c262518 RH |
7151 | read-only vs read-write data, and @code{flag_pic}. You should only |
7152 | need to override this if your target has special flags that might be | |
7153 | set via @code{__attribute__}. | |
7154 | @end deftypefn | |
7155 | ||
e0d9d0dd NC |
7156 | @deftypefn {Target Hook} {int} TARGET_ASM_RECORD_GCC_SWITCHES (print_switch_type @var{type}, const char * @var{text}) |
7157 | Provides the target with the ability to record the gcc command line | |
7158 | switches that have been passed to the compiler, and options that are | |
7159 | enabled. The @var{type} argument specifies what is being recorded. | |
7160 | It can take the following values: | |
7161 | ||
7162 | @table @gcctabopt | |
7163 | @item SWITCH_TYPE_PASSED | |
7164 | @var{text} is a command line switch that has been set by the user. | |
7165 | ||
7166 | @item SWITCH_TYPE_ENABLED | |
7167 | @var{text} is an option which has been enabled. This might be as a | |
7168 | direct result of a command line switch, or because it is enabled by | |
7169 | default or because it has been enabled as a side effect of a different | |
7170 | command line switch. For example, the @option{-O2} switch enables | |
7171 | various different individual optimization passes. | |
7172 | ||
7173 | @item SWITCH_TYPE_DESCRIPTIVE | |
7174 | @var{text} is either NULL or some descriptive text which should be | |
7175 | ignored. If @var{text} is NULL then it is being used to warn the | |
7176 | target hook that either recording is starting or ending. The first | |
7177 | time @var{type} is SWITCH_TYPE_DESCRIPTIVE and @var{text} is NULL, the | |
7178 | warning is for start up and the second time the warning is for | |
7179 | wind down. This feature is to allow the target hook to make any | |
7180 | necessary preparations before it starts to record switches and to | |
7181 | perform any necessary tidying up after it has finished recording | |
7182 | switches. | |
7183 | ||
7184 | @item SWITCH_TYPE_LINE_START | |
7185 | This option can be ignored by this target hook. | |
7186 | ||
7187 | @item SWITCH_TYPE_LINE_END | |
7188 | This option can be ignored by this target hook. | |
7189 | @end table | |
7190 | ||
7191 | The hook's return value must be zero. Other return values may be | |
7192 | supported in the future. | |
7193 | ||
7194 | By default this hook is set to NULL, but an example implementation is | |
7195 | provided for ELF based targets. Called @var{elf_record_gcc_switches}, | |
7196 | it records the switches as ASCII text inside a new, string mergeable | |
7197 | section in the assembler output file. The name of the new section is | |
7198 | provided by the @code{TARGET_ASM_RECORD_GCC_SWITCHES_SECTION} target | |
7199 | hook. | |
7200 | @end deftypefn | |
7201 | ||
7202 | @deftypefn {Target Hook} {const char *} TARGET_ASM_RECORD_GCC_SWITCHES_SECTION | |
7203 | This is the name of the section that will be created by the example | |
7204 | ELF implementation of the @code{TARGET_ASM_RECORD_GCC_SWITCHES} target | |
7205 | hook. | |
7206 | @end deftypefn | |
7207 | ||
feca2ed3 JW |
7208 | @need 2000 |
7209 | @node Data Output | |
7210 | @subsection Output of Data | |
7211 | ||
301d03af RS |
7212 | |
7213 | @deftypevr {Target Hook} {const char *} TARGET_ASM_BYTE_OP | |
7214 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_HI_OP | |
7215 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_SI_OP | |
7216 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_DI_OP | |
7217 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_ALIGNED_TI_OP | |
7218 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_HI_OP | |
7219 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_SI_OP | |
7220 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_DI_OP | |
7221 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_UNALIGNED_TI_OP | |
7222 | These hooks specify assembly directives for creating certain kinds | |
7223 | of integer object. The @code{TARGET_ASM_BYTE_OP} directive creates a | |
7224 | byte-sized object, the @code{TARGET_ASM_ALIGNED_HI_OP} one creates an | |
7225 | aligned two-byte object, and so on. Any of the hooks may be | |
7226 | @code{NULL}, indicating that no suitable directive is available. | |
7227 | ||
7228 | The compiler will print these strings at the start of a new line, | |
7229 | followed immediately by the object's initial value. In most cases, | |
7230 | the string should contain a tab, a pseudo-op, and then another tab. | |
7231 | @end deftypevr | |
7232 | ||
7233 | @deftypefn {Target Hook} bool TARGET_ASM_INTEGER (rtx @var{x}, unsigned int @var{size}, int @var{aligned_p}) | |
7234 | The @code{assemble_integer} function uses this hook to output an | |
7235 | integer object. @var{x} is the object's value, @var{size} is its size | |
7236 | in bytes and @var{aligned_p} indicates whether it is aligned. The | |
7237 | function should return @code{true} if it was able to output the | |
7238 | object. If it returns false, @code{assemble_integer} will try to | |
7239 | split the object into smaller parts. | |
7240 | ||
7241 | The default implementation of this hook will use the | |
7242 | @code{TARGET_ASM_BYTE_OP} family of strings, returning @code{false} | |
7243 | when the relevant string is @code{NULL}. | |
7244 | @end deftypefn | |
feca2ed3 | 7245 | |
a2c4f8e0 | 7246 | @defmac OUTPUT_ADDR_CONST_EXTRA (@var{stream}, @var{x}, @var{fail}) |
422be3c3 AO |
7247 | A C statement to recognize @var{rtx} patterns that |
7248 | @code{output_addr_const} can't deal with, and output assembly code to | |
7249 | @var{stream} corresponding to the pattern @var{x}. This may be used to | |
7250 | allow machine-dependent @code{UNSPEC}s to appear within constants. | |
7251 | ||
7252 | If @code{OUTPUT_ADDR_CONST_EXTRA} fails to recognize a pattern, it must | |
7253 | @code{goto fail}, so that a standard error message is printed. If it | |
7254 | prints an error message itself, by calling, for example, | |
7255 | @code{output_operand_lossage}, it may just complete normally. | |
a2c4f8e0 | 7256 | @end defmac |
422be3c3 | 7257 | |
a2c4f8e0 | 7258 | @defmac ASM_OUTPUT_ASCII (@var{stream}, @var{ptr}, @var{len}) |
feca2ed3 JW |
7259 | A C statement to output to the stdio stream @var{stream} an assembler |
7260 | instruction to assemble a string constant containing the @var{len} | |
7261 | bytes at @var{ptr}. @var{ptr} will be a C expression of type | |
7262 | @code{char *} and @var{len} a C expression of type @code{int}. | |
7263 | ||
7264 | If the assembler has a @code{.ascii} pseudo-op as found in the | |
7265 | Berkeley Unix assembler, do not define the macro | |
7266 | @code{ASM_OUTPUT_ASCII}. | |
a2c4f8e0 | 7267 | @end defmac |
feca2ed3 | 7268 | |
a2c4f8e0 | 7269 | @defmac ASM_OUTPUT_FDESC (@var{stream}, @var{decl}, @var{n}) |
67231816 RH |
7270 | A C statement to output word @var{n} of a function descriptor for |
7271 | @var{decl}. This must be defined if @code{TARGET_VTABLE_USES_DESCRIPTORS} | |
7272 | is defined, and is otherwise unused. | |
a2c4f8e0 | 7273 | @end defmac |
67231816 | 7274 | |
a2c4f8e0 | 7275 | @defmac CONSTANT_POOL_BEFORE_FUNCTION |
861bb6c1 | 7276 | You may define this macro as a C expression. You should define the |
df2a54e9 | 7277 | expression to have a nonzero value if GCC should output the constant |
861bb6c1 | 7278 | pool for a function before the code for the function, or a zero value if |
a3a15b4d JL |
7279 | GCC should output the constant pool after the function. If you do |
7280 | not define this macro, the usual case, GCC will output the constant | |
861bb6c1 | 7281 | pool before the function. |
a2c4f8e0 | 7282 | @end defmac |
861bb6c1 | 7283 | |
a2c4f8e0 | 7284 | @defmac ASM_OUTPUT_POOL_PROLOGUE (@var{file}, @var{funname}, @var{fundecl}, @var{size}) |
feca2ed3 JW |
7285 | A C statement to output assembler commands to define the start of the |
7286 | constant pool for a function. @var{funname} is a string giving | |
7287 | the name of the function. Should the return type of the function | |
7288 | be required, it can be obtained via @var{fundecl}. @var{size} | |
7289 | is the size, in bytes, of the constant pool that will be written | |
7290 | immediately after this call. | |
7291 | ||
7292 | If no constant-pool prefix is required, the usual case, this macro need | |
7293 | not be defined. | |
a2c4f8e0 | 7294 | @end defmac |
feca2ed3 | 7295 | |
a2c4f8e0 | 7296 | @defmac ASM_OUTPUT_SPECIAL_POOL_ENTRY (@var{file}, @var{x}, @var{mode}, @var{align}, @var{labelno}, @var{jumpto}) |
feca2ed3 JW |
7297 | A C statement (with or without semicolon) to output a constant in the |
7298 | constant pool, if it needs special treatment. (This macro need not do | |
7299 | anything for RTL expressions that can be output normally.) | |
7300 | ||
7301 | The argument @var{file} is the standard I/O stream to output the | |
7302 | assembler code on. @var{x} is the RTL expression for the constant to | |
7303 | output, and @var{mode} is the machine mode (in case @var{x} is a | |
7304 | @samp{const_int}). @var{align} is the required alignment for the value | |
7305 | @var{x}; you should output an assembler directive to force this much | |
7306 | alignment. | |
7307 | ||
7308 | The argument @var{labelno} is a number to use in an internal label for | |
7309 | the address of this pool entry. The definition of this macro is | |
7310 | responsible for outputting the label definition at the proper place. | |
7311 | Here is how to do this: | |
7312 | ||
3ab51846 | 7313 | @smallexample |
4977bab6 | 7314 | @code{(*targetm.asm_out.internal_label)} (@var{file}, "LC", @var{labelno}); |
3ab51846 | 7315 | @end smallexample |
feca2ed3 JW |
7316 | |
7317 | When you output a pool entry specially, you should end with a | |
7318 | @code{goto} to the label @var{jumpto}. This will prevent the same pool | |
7319 | entry from being output a second time in the usual manner. | |
7320 | ||
7321 | You need not define this macro if it would do nothing. | |
a2c4f8e0 | 7322 | @end defmac |
feca2ed3 | 7323 | |
a2c4f8e0 | 7324 | @defmac ASM_OUTPUT_POOL_EPILOGUE (@var{file} @var{funname} @var{fundecl} @var{size}) |
861bb6c1 JL |
7325 | A C statement to output assembler commands to at the end of the constant |
7326 | pool for a function. @var{funname} is a string giving the name of the | |
7327 | function. Should the return type of the function be required, you can | |
7328 | obtain it via @var{fundecl}. @var{size} is the size, in bytes, of the | |
a3a15b4d | 7329 | constant pool that GCC wrote immediately before this call. |
861bb6c1 JL |
7330 | |
7331 | If no constant-pool epilogue is required, the usual case, you need not | |
7332 | define this macro. | |
a2c4f8e0 | 7333 | @end defmac |
861bb6c1 | 7334 | |
980d8882 | 7335 | @defmac IS_ASM_LOGICAL_LINE_SEPARATOR (@var{C}, @var{STR}) |
feca2ed3 | 7336 | Define this macro as a C expression which is nonzero if @var{C} is |
980d8882 BS |
7337 | used as a logical line separator by the assembler. @var{STR} points |
7338 | to the position in the string where @var{C} was found; this can be used if | |
7339 | a line separator uses multiple characters. | |
feca2ed3 JW |
7340 | |
7341 | If you do not define this macro, the default is that only | |
7342 | the character @samp{;} is treated as a logical line separator. | |
a2c4f8e0 | 7343 | @end defmac |
feca2ed3 | 7344 | |
8ca83838 | 7345 | @deftypevr {Target Hook} {const char *} TARGET_ASM_OPEN_PAREN |
baed53ac | 7346 | @deftypevrx {Target Hook} {const char *} TARGET_ASM_CLOSE_PAREN |
17b53c33 NB |
7347 | These target hooks are C string constants, describing the syntax in the |
7348 | assembler for grouping arithmetic expressions. If not overridden, they | |
7349 | default to normal parentheses, which is correct for most assemblers. | |
8ca83838 | 7350 | @end deftypevr |
17b53c33 | 7351 | |
6ccde948 | 7352 | These macros are provided by @file{real.h} for writing the definitions |
feca2ed3 JW |
7353 | of @code{ASM_OUTPUT_DOUBLE} and the like: |
7354 | ||
a2c4f8e0 ZW |
7355 | @defmac REAL_VALUE_TO_TARGET_SINGLE (@var{x}, @var{l}) |
7356 | @defmacx REAL_VALUE_TO_TARGET_DOUBLE (@var{x}, @var{l}) | |
7357 | @defmacx REAL_VALUE_TO_TARGET_LONG_DOUBLE (@var{x}, @var{l}) | |
dadb213f BE |
7358 | @defmacx REAL_VALUE_TO_TARGET_DECIMAL32 (@var{x}, @var{l}) |
7359 | @defmacx REAL_VALUE_TO_TARGET_DECIMAL64 (@var{x}, @var{l}) | |
7360 | @defmacx REAL_VALUE_TO_TARGET_DECIMAL128 (@var{x}, @var{l}) | |
7361 | These translate @var{x}, of type @code{REAL_VALUE_TYPE}, to the | |
7362 | target's floating point representation, and store its bit pattern in | |
7363 | the variable @var{l}. For @code{REAL_VALUE_TO_TARGET_SINGLE} and | |
7364 | @code{REAL_VALUE_TO_TARGET_DECIMAL32}, this variable should be a | |
7365 | simple @code{long int}. For the others, it should be an array of | |
7366 | @code{long int}. The number of elements in this array is determined | |
7367 | by the size of the desired target floating point data type: 32 bits of | |
7368 | it go in each @code{long int} array element. Each array element holds | |
7369 | 32 bits of the result, even if @code{long int} is wider than 32 bits | |
7370 | on the host machine. | |
feca2ed3 JW |
7371 | |
7372 | The array element values are designed so that you can print them out | |
7373 | using @code{fprintf} in the order they should appear in the target | |
7374 | machine's memory. | |
a2c4f8e0 | 7375 | @end defmac |
feca2ed3 JW |
7376 | |
7377 | @node Uninitialized Data | |
7378 | @subsection Output of Uninitialized Variables | |
7379 | ||
7380 | Each of the macros in this section is used to do the whole job of | |
7381 | outputting a single uninitialized variable. | |
7382 | ||
a2c4f8e0 | 7383 | @defmac ASM_OUTPUT_COMMON (@var{stream}, @var{name}, @var{size}, @var{rounded}) |
feca2ed3 JW |
7384 | A C statement (sans semicolon) to output to the stdio stream |
7385 | @var{stream} the assembler definition of a common-label named | |
7386 | @var{name} whose size is @var{size} bytes. The variable @var{rounded} | |
233215fe DK |
7387 | is the size rounded up to whatever alignment the caller wants. It is |
7388 | possible that @var{size} may be zero, for instance if a struct with no | |
7389 | other member than a zero-length array is defined. In this case, the | |
7390 | backend must output a symbol definition that allocates at least one | |
7391 | byte, both so that the address of the resulting object does not compare | |
7392 | equal to any other, and because some object formats cannot even express | |
7393 | the concept of a zero-sized common symbol, as that is how they represent | |
7394 | an ordinary undefined external. | |
feca2ed3 JW |
7395 | |
7396 | Use the expression @code{assemble_name (@var{stream}, @var{name})} to | |
7397 | output the name itself; before and after that, output the additional | |
7398 | assembler syntax for defining the name, and a newline. | |
7399 | ||
7400 | This macro controls how the assembler definitions of uninitialized | |
7401 | common global variables are output. | |
a2c4f8e0 | 7402 | @end defmac |
feca2ed3 | 7403 | |
a2c4f8e0 | 7404 | @defmac ASM_OUTPUT_ALIGNED_COMMON (@var{stream}, @var{name}, @var{size}, @var{alignment}) |
feca2ed3 JW |
7405 | Like @code{ASM_OUTPUT_COMMON} except takes the required alignment as a |
7406 | separate, explicit argument. If you define this macro, it is used in | |
7407 | place of @code{ASM_OUTPUT_COMMON}, and gives you more flexibility in | |
7408 | handling the required alignment of the variable. The alignment is specified | |
7409 | as the number of bits. | |
a2c4f8e0 | 7410 | @end defmac |
feca2ed3 | 7411 | |
a2c4f8e0 | 7412 | @defmac ASM_OUTPUT_ALIGNED_DECL_COMMON (@var{stream}, @var{decl}, @var{name}, @var{size}, @var{alignment}) |
e9a25f70 JL |
7413 | Like @code{ASM_OUTPUT_ALIGNED_COMMON} except that @var{decl} of the |
7414 | variable to be output, if there is one, or @code{NULL_TREE} if there | |
8760eaae | 7415 | is no corresponding variable. If you define this macro, GCC will use it |
e9a25f70 JL |
7416 | in place of both @code{ASM_OUTPUT_COMMON} and |
7417 | @code{ASM_OUTPUT_ALIGNED_COMMON}. Define this macro when you need to see | |
7418 | the variable's decl in order to chose what to output. | |
a2c4f8e0 | 7419 | @end defmac |
e9a25f70 | 7420 | |
a2c4f8e0 | 7421 | @defmac ASM_OUTPUT_BSS (@var{stream}, @var{decl}, @var{name}, @var{size}, @var{rounded}) |
feca2ed3 JW |
7422 | A C statement (sans semicolon) to output to the stdio stream |
7423 | @var{stream} the assembler definition of uninitialized global @var{decl} named | |
7424 | @var{name} whose size is @var{size} bytes. The variable @var{rounded} | |
7425 | is the size rounded up to whatever alignment the caller wants. | |
7426 | ||
7427 | Try to use function @code{asm_output_bss} defined in @file{varasm.c} when | |
7428 | defining this macro. If unable, use the expression | |
7429 | @code{assemble_name (@var{stream}, @var{name})} to output the name itself; | |
7430 | before and after that, output the additional assembler syntax for defining | |
7431 | the name, and a newline. | |
7432 | ||
0ee2ea09 | 7433 | There are two ways of handling global BSS@. One is to define either |
434aeebb RS |
7434 | this macro or its aligned counterpart, @code{ASM_OUTPUT_ALIGNED_BSS}. |
7435 | The other is to have @code{TARGET_ASM_SELECT_SECTION} return a | |
7436 | switchable BSS section (@pxref{TARGET_HAVE_SWITCHABLE_BSS_SECTIONS}). | |
7437 | You do not need to do both. | |
7438 | ||
7439 | Some languages do not have @code{common} data, and require a | |
7440 | non-common form of global BSS in order to handle uninitialized globals | |
7441 | efficiently. C++ is one example of this. However, if the target does | |
7442 | not support global BSS, the front end may choose to make globals | |
7443 | common in order to save space in the object file. | |
a2c4f8e0 | 7444 | @end defmac |
feca2ed3 | 7445 | |
a2c4f8e0 | 7446 | @defmac ASM_OUTPUT_ALIGNED_BSS (@var{stream}, @var{decl}, @var{name}, @var{size}, @var{alignment}) |
feca2ed3 JW |
7447 | Like @code{ASM_OUTPUT_BSS} except takes the required alignment as a |
7448 | separate, explicit argument. If you define this macro, it is used in | |
7449 | place of @code{ASM_OUTPUT_BSS}, and gives you more flexibility in | |
7450 | handling the required alignment of the variable. The alignment is specified | |
7451 | as the number of bits. | |
7452 | ||
7453 | Try to use function @code{asm_output_aligned_bss} defined in file | |
7454 | @file{varasm.c} when defining this macro. | |
a2c4f8e0 | 7455 | @end defmac |
feca2ed3 | 7456 | |
a2c4f8e0 | 7457 | @defmac ASM_OUTPUT_LOCAL (@var{stream}, @var{name}, @var{size}, @var{rounded}) |
feca2ed3 JW |
7458 | A C statement (sans semicolon) to output to the stdio stream |
7459 | @var{stream} the assembler definition of a local-common-label named | |
7460 | @var{name} whose size is @var{size} bytes. The variable @var{rounded} | |
7461 | is the size rounded up to whatever alignment the caller wants. | |
7462 | ||
7463 | Use the expression @code{assemble_name (@var{stream}, @var{name})} to | |
7464 | output the name itself; before and after that, output the additional | |
7465 | assembler syntax for defining the name, and a newline. | |
7466 | ||
7467 | This macro controls how the assembler definitions of uninitialized | |
7468 | static variables are output. | |
a2c4f8e0 | 7469 | @end defmac |
feca2ed3 | 7470 | |
a2c4f8e0 | 7471 | @defmac ASM_OUTPUT_ALIGNED_LOCAL (@var{stream}, @var{name}, @var{size}, @var{alignment}) |
feca2ed3 JW |
7472 | Like @code{ASM_OUTPUT_LOCAL} except takes the required alignment as a |
7473 | separate, explicit argument. If you define this macro, it is used in | |
7474 | place of @code{ASM_OUTPUT_LOCAL}, and gives you more flexibility in | |
7475 | handling the required alignment of the variable. The alignment is specified | |
7476 | as the number of bits. | |
a2c4f8e0 | 7477 | @end defmac |
feca2ed3 | 7478 | |
a2c4f8e0 | 7479 | @defmac ASM_OUTPUT_ALIGNED_DECL_LOCAL (@var{stream}, @var{decl}, @var{name}, @var{size}, @var{alignment}) |
e9a25f70 JL |
7480 | Like @code{ASM_OUTPUT_ALIGNED_DECL} except that @var{decl} of the |
7481 | variable to be output, if there is one, or @code{NULL_TREE} if there | |
8760eaae | 7482 | is no corresponding variable. If you define this macro, GCC will use it |
e9a25f70 JL |
7483 | in place of both @code{ASM_OUTPUT_DECL} and |
7484 | @code{ASM_OUTPUT_ALIGNED_DECL}. Define this macro when you need to see | |
7485 | the variable's decl in order to chose what to output. | |
a2c4f8e0 | 7486 | @end defmac |
e9a25f70 | 7487 | |
feca2ed3 JW |
7488 | @node Label Output |
7489 | @subsection Output and Generation of Labels | |
7490 | ||
7491 | @c prevent bad page break with this line | |
7492 | This is about outputting labels. | |
7493 | ||
feca2ed3 | 7494 | @findex assemble_name |
a2c4f8e0 | 7495 | @defmac ASM_OUTPUT_LABEL (@var{stream}, @var{name}) |
feca2ed3 JW |
7496 | A C statement (sans semicolon) to output to the stdio stream |
7497 | @var{stream} the assembler definition of a label named @var{name}. | |
7498 | Use the expression @code{assemble_name (@var{stream}, @var{name})} to | |
7499 | output the name itself; before and after that, output the additional | |
4ad5e05d KG |
7500 | assembler syntax for defining the name, and a newline. A default |
7501 | definition of this macro is provided which is correct for most systems. | |
a2c4f8e0 | 7502 | @end defmac |
feca2ed3 | 7503 | |
57829bc4 MM |
7504 | @findex assemble_name_raw |
7505 | @defmac ASM_OUTPUT_INTERNAL_LABEL (@var{stream}, @var{name}) | |
e374d5c9 | 7506 | Identical to @code{ASM_OUTPUT_LABEL}, except that @var{name} is known |
57829bc4 MM |
7507 | to refer to a compiler-generated label. The default definition uses |
7508 | @code{assemble_name_raw}, which is like @code{assemble_name} except | |
7509 | that it is more efficient. | |
7510 | @end defmac | |
7511 | ||
a2c4f8e0 | 7512 | @defmac SIZE_ASM_OP |
2be2ac70 ZW |
7513 | A C string containing the appropriate assembler directive to specify the |
7514 | size of a symbol, without any arguments. On systems that use ELF, the | |
7515 | default (in @file{config/elfos.h}) is @samp{"\t.size\t"}; on other | |
7516 | systems, the default is not to define this macro. | |
7517 | ||
7518 | Define this macro only if it is correct to use the default definitions | |
7519 | of @code{ASM_OUTPUT_SIZE_DIRECTIVE} and @code{ASM_OUTPUT_MEASURED_SIZE} | |
7520 | for your system. If you need your own custom definitions of those | |
7521 | macros, or if you do not need explicit symbol sizes at all, do not | |
7522 | define this macro. | |
a2c4f8e0 | 7523 | @end defmac |
2be2ac70 | 7524 | |
a2c4f8e0 | 7525 | @defmac ASM_OUTPUT_SIZE_DIRECTIVE (@var{stream}, @var{name}, @var{size}) |
2be2ac70 ZW |
7526 | A C statement (sans semicolon) to output to the stdio stream |
7527 | @var{stream} a directive telling the assembler that the size of the | |
7528 | symbol @var{name} is @var{size}. @var{size} is a @code{HOST_WIDE_INT}. | |
7529 | If you define @code{SIZE_ASM_OP}, a default definition of this macro is | |
7530 | provided. | |
a2c4f8e0 | 7531 | @end defmac |
2be2ac70 | 7532 | |
a2c4f8e0 | 7533 | @defmac ASM_OUTPUT_MEASURED_SIZE (@var{stream}, @var{name}) |
2be2ac70 ZW |
7534 | A C statement (sans semicolon) to output to the stdio stream |
7535 | @var{stream} a directive telling the assembler to calculate the size of | |
99086d59 | 7536 | the symbol @var{name} by subtracting its address from the current |
73774972 | 7537 | address. |
99086d59 ZW |
7538 | |
7539 | If you define @code{SIZE_ASM_OP}, a default definition of this macro is | |
7540 | provided. The default assumes that the assembler recognizes a special | |
7541 | @samp{.} symbol as referring to the current address, and can calculate | |
7542 | the difference between this and another symbol. If your assembler does | |
7543 | not recognize @samp{.} or cannot do calculations with it, you will need | |
7544 | to redefine @code{ASM_OUTPUT_MEASURED_SIZE} to use some other technique. | |
a2c4f8e0 | 7545 | @end defmac |
2be2ac70 | 7546 | |
a2c4f8e0 | 7547 | @defmac TYPE_ASM_OP |
2be2ac70 ZW |
7548 | A C string containing the appropriate assembler directive to specify the |
7549 | type of a symbol, without any arguments. On systems that use ELF, the | |
7550 | default (in @file{config/elfos.h}) is @samp{"\t.type\t"}; on other | |
7551 | systems, the default is not to define this macro. | |
7552 | ||
7553 | Define this macro only if it is correct to use the default definition of | |
7554 | @code{ASM_OUTPUT_TYPE_DIRECTIVE} for your system. If you need your own | |
7555 | custom definition of this macro, or if you do not need explicit symbol | |
7556 | types at all, do not define this macro. | |
a2c4f8e0 | 7557 | @end defmac |
2be2ac70 | 7558 | |
a2c4f8e0 | 7559 | @defmac TYPE_OPERAND_FMT |
2be2ac70 ZW |
7560 | A C string which specifies (using @code{printf} syntax) the format of |
7561 | the second operand to @code{TYPE_ASM_OP}. On systems that use ELF, the | |
7562 | default (in @file{config/elfos.h}) is @samp{"@@%s"}; on other systems, | |
7563 | the default is not to define this macro. | |
7564 | ||
7565 | Define this macro only if it is correct to use the default definition of | |
7566 | @code{ASM_OUTPUT_TYPE_DIRECTIVE} for your system. If you need your own | |
7567 | custom definition of this macro, or if you do not need explicit symbol | |
7568 | types at all, do not define this macro. | |
a2c4f8e0 | 7569 | @end defmac |
2be2ac70 | 7570 | |
a2c4f8e0 | 7571 | @defmac ASM_OUTPUT_TYPE_DIRECTIVE (@var{stream}, @var{type}) |
2be2ac70 ZW |
7572 | A C statement (sans semicolon) to output to the stdio stream |
7573 | @var{stream} a directive telling the assembler that the type of the | |
7574 | symbol @var{name} is @var{type}. @var{type} is a C string; currently, | |
7575 | that string is always either @samp{"function"} or @samp{"object"}, but | |
7576 | you should not count on this. | |
7577 | ||
7578 | If you define @code{TYPE_ASM_OP} and @code{TYPE_OPERAND_FMT}, a default | |
7579 | definition of this macro is provided. | |
a2c4f8e0 | 7580 | @end defmac |
2be2ac70 | 7581 | |
a2c4f8e0 | 7582 | @defmac ASM_DECLARE_FUNCTION_NAME (@var{stream}, @var{name}, @var{decl}) |
feca2ed3 JW |
7583 | A C statement (sans semicolon) to output to the stdio stream |
7584 | @var{stream} any text necessary for declaring the name @var{name} of a | |
7585 | function which is being defined. This macro is responsible for | |
7586 | outputting the label definition (perhaps using | |
7587 | @code{ASM_OUTPUT_LABEL}). The argument @var{decl} is the | |
7588 | @code{FUNCTION_DECL} tree node representing the function. | |
7589 | ||
7590 | If this macro is not defined, then the function name is defined in the | |
7591 | usual manner as a label (by means of @code{ASM_OUTPUT_LABEL}). | |
7592 | ||
2be2ac70 ZW |
7593 | You may wish to use @code{ASM_OUTPUT_TYPE_DIRECTIVE} in the definition |
7594 | of this macro. | |
a2c4f8e0 | 7595 | @end defmac |
2be2ac70 | 7596 | |
a2c4f8e0 | 7597 | @defmac ASM_DECLARE_FUNCTION_SIZE (@var{stream}, @var{name}, @var{decl}) |
feca2ed3 JW |
7598 | A C statement (sans semicolon) to output to the stdio stream |
7599 | @var{stream} any text necessary for declaring the size of a function | |
7600 | which is being defined. The argument @var{name} is the name of the | |
7601 | function. The argument @var{decl} is the @code{FUNCTION_DECL} tree node | |
7602 | representing the function. | |
7603 | ||
7604 | If this macro is not defined, then the function size is not defined. | |
7605 | ||
2be2ac70 ZW |
7606 | You may wish to use @code{ASM_OUTPUT_MEASURED_SIZE} in the definition |
7607 | of this macro. | |
a2c4f8e0 | 7608 | @end defmac |
2be2ac70 | 7609 | |
a2c4f8e0 | 7610 | @defmac ASM_DECLARE_OBJECT_NAME (@var{stream}, @var{name}, @var{decl}) |
feca2ed3 JW |
7611 | A C statement (sans semicolon) to output to the stdio stream |
7612 | @var{stream} any text necessary for declaring the name @var{name} of an | |
7613 | initialized variable which is being defined. This macro must output the | |
7614 | label definition (perhaps using @code{ASM_OUTPUT_LABEL}). The argument | |
7615 | @var{decl} is the @code{VAR_DECL} tree node representing the variable. | |
7616 | ||
7617 | If this macro is not defined, then the variable name is defined in the | |
7618 | usual manner as a label (by means of @code{ASM_OUTPUT_LABEL}). | |
7619 | ||
2be2ac70 ZW |
7620 | You may wish to use @code{ASM_OUTPUT_TYPE_DIRECTIVE} and/or |
7621 | @code{ASM_OUTPUT_SIZE_DIRECTIVE} in the definition of this macro. | |
a2c4f8e0 | 7622 | @end defmac |
2be2ac70 | 7623 | |
18f3e349 GK |
7624 | @defmac ASM_DECLARE_CONSTANT_NAME (@var{stream}, @var{name}, @var{exp}, @var{size}) |
7625 | A C statement (sans semicolon) to output to the stdio stream | |
7626 | @var{stream} any text necessary for declaring the name @var{name} of a | |
7627 | constant which is being defined. This macro is responsible for | |
7628 | outputting the label definition (perhaps using | |
7629 | @code{ASM_OUTPUT_LABEL}). The argument @var{exp} is the | |
7630 | value of the constant, and @var{size} is the size of the constant | |
7631 | in bytes. @var{name} will be an internal label. | |
7632 | ||
7633 | If this macro is not defined, then the @var{name} is defined in the | |
7634 | usual manner as a label (by means of @code{ASM_OUTPUT_LABEL}). | |
7635 | ||
7636 | You may wish to use @code{ASM_OUTPUT_TYPE_DIRECTIVE} in the definition | |
7637 | of this macro. | |
7638 | @end defmac | |
7639 | ||
a2c4f8e0 | 7640 | @defmac ASM_DECLARE_REGISTER_GLOBAL (@var{stream}, @var{decl}, @var{regno}, @var{name}) |
1cb36a98 RH |
7641 | A C statement (sans semicolon) to output to the stdio stream |
7642 | @var{stream} any text necessary for claiming a register @var{regno} | |
7643 | for a global variable @var{decl} with name @var{name}. | |
7644 | ||
7645 | If you don't define this macro, that is equivalent to defining it to do | |
7646 | nothing. | |
a2c4f8e0 | 7647 | @end defmac |
1cb36a98 | 7648 | |
a2c4f8e0 | 7649 | @defmac ASM_FINISH_DECLARE_OBJECT (@var{stream}, @var{decl}, @var{toplevel}, @var{atend}) |
feca2ed3 JW |
7650 | A C statement (sans semicolon) to finish up declaring a variable name |
7651 | once the compiler has processed its initializer fully and thus has had a | |
7652 | chance to determine the size of an array when controlled by an | |
7653 | initializer. This is used on systems where it's necessary to declare | |
7654 | something about the size of the object. | |
7655 | ||
7656 | If you don't define this macro, that is equivalent to defining it to do | |
7657 | nothing. | |
7658 | ||
2be2ac70 ZW |
7659 | You may wish to use @code{ASM_OUTPUT_SIZE_DIRECTIVE} and/or |
7660 | @code{ASM_OUTPUT_MEASURED_SIZE} in the definition of this macro. | |
a2c4f8e0 | 7661 | @end defmac |
2be2ac70 | 7662 | |
5eb99654 KG |
7663 | @deftypefn {Target Hook} void TARGET_ASM_GLOBALIZE_LABEL (FILE *@var{stream}, const char *@var{name}) |
7664 | This target hook is a function to output to the stdio stream | |
feca2ed3 | 7665 | @var{stream} some commands that will make the label @var{name} global; |
5eb99654 | 7666 | that is, available for reference from other files. |
feca2ed3 | 7667 | |
5eb99654 KG |
7668 | The default implementation relies on a proper definition of |
7669 | @code{GLOBAL_ASM_OP}. | |
b65d23aa | 7670 | @end deftypefn |
072cdaed | 7671 | |
812b587e SE |
7672 | @deftypefn {Target Hook} void TARGET_ASM_GLOBALIZE_DECL_NAME (FILE *@var{stream}, tree @var{decl}) |
7673 | This target hook is a function to output to the stdio stream | |
7674 | @var{stream} some commands that will make the name associated with @var{decl} | |
7675 | global; that is, available for reference from other files. | |
7676 | ||
7677 | The default implementation uses the TARGET_ASM_GLOBALIZE_LABEL target hook. | |
7678 | @end deftypefn | |
7679 | ||
a2c4f8e0 | 7680 | @defmac ASM_WEAKEN_LABEL (@var{stream}, @var{name}) |
feca2ed3 JW |
7681 | A C statement (sans semicolon) to output to the stdio stream |
7682 | @var{stream} some commands that will make the label @var{name} weak; | |
7683 | that is, available for reference from other files but only used if | |
7684 | no other definition is available. Use the expression | |
7685 | @code{assemble_name (@var{stream}, @var{name})} to output the name | |
7686 | itself; before and after that, output the additional assembler syntax | |
7687 | for making that name weak, and a newline. | |
7688 | ||
79c4e63f AM |
7689 | If you don't define this macro or @code{ASM_WEAKEN_DECL}, GCC will not |
7690 | support weak symbols and you should not define the @code{SUPPORTS_WEAK} | |
7691 | macro. | |
a2c4f8e0 | 7692 | @end defmac |
79c4e63f | 7693 | |
a2c4f8e0 | 7694 | @defmac ASM_WEAKEN_DECL (@var{stream}, @var{decl}, @var{name}, @var{value}) |
79c4e63f AM |
7695 | Combines (and replaces) the function of @code{ASM_WEAKEN_LABEL} and |
7696 | @code{ASM_OUTPUT_WEAK_ALIAS}, allowing access to the associated function | |
7697 | or variable decl. If @var{value} is not @code{NULL}, this C statement | |
7698 | should output to the stdio stream @var{stream} assembler code which | |
7699 | defines (equates) the weak symbol @var{name} to have the value | |
7700 | @var{value}. If @var{value} is @code{NULL}, it should output commands | |
7701 | to make @var{name} weak. | |
a2c4f8e0 | 7702 | @end defmac |
feca2ed3 | 7703 | |
ff2d10c1 AO |
7704 | @defmac ASM_OUTPUT_WEAKREF (@var{stream}, @var{decl}, @var{name}, @var{value}) |
7705 | Outputs a directive that enables @var{name} to be used to refer to | |
7706 | symbol @var{value} with weak-symbol semantics. @code{decl} is the | |
7707 | declaration of @code{name}. | |
7708 | @end defmac | |
7709 | ||
a2c4f8e0 | 7710 | @defmac SUPPORTS_WEAK |
feca2ed3 JW |
7711 | A C expression which evaluates to true if the target supports weak symbols. |
7712 | ||
7713 | If you don't define this macro, @file{defaults.h} provides a default | |
79c4e63f AM |
7714 | definition. If either @code{ASM_WEAKEN_LABEL} or @code{ASM_WEAKEN_DECL} |
7715 | is defined, the default definition is @samp{1}; otherwise, it is | |
7716 | @samp{0}. Define this macro if you want to control weak symbol support | |
7717 | with a compiler flag such as @option{-melf}. | |
a2c4f8e0 | 7718 | @end defmac |
feca2ed3 | 7719 | |
a2c4f8e0 | 7720 | @defmac MAKE_DECL_ONE_ONLY (@var{decl}) |
feca2ed3 JW |
7721 | A C statement (sans semicolon) to mark @var{decl} to be emitted as a |
7722 | public symbol such that extra copies in multiple translation units will | |
7723 | be discarded by the linker. Define this macro if your object file | |
7724 | format provides support for this concept, such as the @samp{COMDAT} | |
7725 | section flags in the Microsoft Windows PE/COFF format, and this support | |
7726 | requires changes to @var{decl}, such as putting it in a separate section. | |
a2c4f8e0 | 7727 | @end defmac |
feca2ed3 | 7728 | |
a2c4f8e0 | 7729 | @defmac SUPPORTS_ONE_ONLY |
feca2ed3 JW |
7730 | A C expression which evaluates to true if the target supports one-only |
7731 | semantics. | |
7732 | ||
7733 | If you don't define this macro, @file{varasm.c} provides a default | |
7734 | definition. If @code{MAKE_DECL_ONE_ONLY} is defined, the default | |
7735 | definition is @samp{1}; otherwise, it is @samp{0}. Define this macro if | |
e9a25f70 | 7736 | you want to control one-only symbol support with a compiler flag, or if |
feca2ed3 JW |
7737 | setting the @code{DECL_ONE_ONLY} flag is enough to mark a declaration to |
7738 | be emitted as one-only. | |
a2c4f8e0 | 7739 | @end defmac |
feca2ed3 | 7740 | |
93638d7a AM |
7741 | @deftypefn {Target Hook} void TARGET_ASM_ASSEMBLE_VISIBILITY (tree @var{decl}, const char *@var{visibility}) |
7742 | This target hook is a function to output to @var{asm_out_file} some | |
7743 | commands that will make the symbol(s) associated with @var{decl} have | |
7744 | hidden, protected or internal visibility as specified by @var{visibility}. | |
7745 | @end deftypefn | |
7746 | ||
0524c91d | 7747 | @defmac TARGET_WEAK_NOT_IN_ARCHIVE_TOC |
4746cf84 | 7748 | A C expression that evaluates to true if the target's linker expects |
0524c91d | 7749 | that weak symbols do not appear in a static archive's table of contents. |
f676971a | 7750 | The default is @code{0}. |
0524c91d MA |
7751 | |
7752 | Leaving weak symbols out of an archive's table of contents means that, | |
7753 | if a symbol will only have a definition in one translation unit and | |
7754 | will have undefined references from other translation units, that | |
7755 | symbol should not be weak. Defining this macro to be nonzero will | |
7756 | thus have the effect that certain symbols that would normally be weak | |
7757 | (explicit template instantiations, and vtables for polymorphic classes | |
7758 | with noninline key methods) will instead be nonweak. | |
7759 | ||
7760 | The C++ ABI requires this macro to be zero. Define this macro for | |
7761 | targets where full C++ ABI compliance is impossible and where linker | |
7762 | restrictions require weak symbols to be left out of a static archive's | |
7763 | table of contents. | |
4746cf84 MA |
7764 | @end defmac |
7765 | ||
a2c4f8e0 | 7766 | @defmac ASM_OUTPUT_EXTERNAL (@var{stream}, @var{decl}, @var{name}) |
feca2ed3 JW |
7767 | A C statement (sans semicolon) to output to the stdio stream |
7768 | @var{stream} any text necessary for declaring the name of an external | |
7769 | symbol named @var{name} which is referenced in this compilation but | |
7770 | not defined. The value of @var{decl} is the tree node for the | |
7771 | declaration. | |
7772 | ||
7773 | This macro need not be defined if it does not need to output anything. | |
7774 | The GNU assembler and most Unix assemblers don't require anything. | |
a2c4f8e0 | 7775 | @end defmac |
feca2ed3 | 7776 | |
6773a41c RO |
7777 | @deftypefn {Target Hook} void TARGET_ASM_EXTERNAL_LIBCALL (rtx @var{symref}) |
7778 | This target hook is a function to output to @var{asm_out_file} an assembler | |
feca2ed3 | 7779 | pseudo-op to declare a library function name external. The name of the |
6773a41c RO |
7780 | library function is given by @var{symref}, which is a @code{symbol_ref}. |
7781 | @end deftypefn | |
feca2ed3 | 7782 | |
8e3e233b DP |
7783 | @deftypefn {Target Hook} void TARGET_ASM_MARK_DECL_PRESERVED (tree @var{decl}) |
7784 | This target hook is a function to output to @var{asm_out_file} an assembler | |
7785 | directive to annotate used symbol. Darwin target use .no_dead_code_strip | |
7786 | directive. | |
7787 | @end deftypefn | |
7788 | ||
a2c4f8e0 | 7789 | @defmac ASM_OUTPUT_LABELREF (@var{stream}, @var{name}) |
feca2ed3 JW |
7790 | A C statement (sans semicolon) to output to the stdio stream |
7791 | @var{stream} a reference in assembler syntax to a label named | |
7792 | @var{name}. This should add @samp{_} to the front of the name, if that | |
7793 | is customary on your operating system, as it is in most Berkeley Unix | |
7794 | systems. This macro is used in @code{assemble_name}. | |
a2c4f8e0 | 7795 | @end defmac |
feca2ed3 | 7796 | |
a2c4f8e0 | 7797 | @defmac ASM_OUTPUT_SYMBOL_REF (@var{stream}, @var{sym}) |
99c8c61c | 7798 | A C statement (sans semicolon) to output a reference to |
2f0b7af6 | 7799 | @code{SYMBOL_REF} @var{sym}. If not defined, @code{assemble_name} |
99c8c61c AO |
7800 | will be used to output the name of the symbol. This macro may be used |
7801 | to modify the way a symbol is referenced depending on information | |
fb49053f | 7802 | encoded by @code{TARGET_ENCODE_SECTION_INFO}. |
a2c4f8e0 | 7803 | @end defmac |
99c8c61c | 7804 | |
a2c4f8e0 | 7805 | @defmac ASM_OUTPUT_LABEL_REF (@var{stream}, @var{buf}) |
2f0b7af6 | 7806 | A C statement (sans semicolon) to output a reference to @var{buf}, the |
4226378a | 7807 | result of @code{ASM_GENERATE_INTERNAL_LABEL}. If not defined, |
2f0b7af6 GK |
7808 | @code{assemble_name} will be used to output the name of the symbol. |
7809 | This macro is not used by @code{output_asm_label}, or the @code{%l} | |
7810 | specifier that calls it; the intention is that this macro should be set | |
4226378a PK |
7811 | when it is necessary to output a label differently when its address is |
7812 | being taken. | |
a2c4f8e0 | 7813 | @end defmac |
2f0b7af6 | 7814 | |
4977bab6 ZW |
7815 | @deftypefn {Target Hook} void TARGET_ASM_INTERNAL_LABEL (FILE *@var{stream}, const char *@var{prefix}, unsigned long @var{labelno}) |
7816 | A function to output to the stdio stream @var{stream} a label whose | |
7817 | name is made from the string @var{prefix} and the number @var{labelno}. | |
feca2ed3 JW |
7818 | |
7819 | It is absolutely essential that these labels be distinct from the labels | |
7820 | used for user-level functions and variables. Otherwise, certain programs | |
7821 | will have name conflicts with internal labels. | |
7822 | ||
7823 | It is desirable to exclude internal labels from the symbol table of the | |
7824 | object file. Most assemblers have a naming convention for labels that | |
7825 | should be excluded; on many systems, the letter @samp{L} at the | |
7826 | beginning of a label has this effect. You should find out what | |
7827 | convention your system uses, and follow it. | |
7828 | ||
8a36672b | 7829 | The default version of this function utilizes @code{ASM_GENERATE_INTERNAL_LABEL}. |
4977bab6 | 7830 | @end deftypefn |
feca2ed3 | 7831 | |
a2c4f8e0 | 7832 | @defmac ASM_OUTPUT_DEBUG_LABEL (@var{stream}, @var{prefix}, @var{num}) |
8215347e JW |
7833 | A C statement to output to the stdio stream @var{stream} a debug info |
7834 | label whose name is made from the string @var{prefix} and the number | |
7835 | @var{num}. This is useful for VLIW targets, where debug info labels | |
7836 | may need to be treated differently than branch target labels. On some | |
7837 | systems, branch target labels must be at the beginning of instruction | |
7838 | bundles, but debug info labels can occur in the middle of instruction | |
7839 | bundles. | |
7840 | ||
4977bab6 | 7841 | If this macro is not defined, then @code{(*targetm.asm_out.internal_label)} will be |
8215347e | 7842 | used. |
a2c4f8e0 | 7843 | @end defmac |
8215347e | 7844 | |
a2c4f8e0 | 7845 | @defmac ASM_GENERATE_INTERNAL_LABEL (@var{string}, @var{prefix}, @var{num}) |
feca2ed3 JW |
7846 | A C statement to store into the string @var{string} a label whose name |
7847 | is made from the string @var{prefix} and the number @var{num}. | |
7848 | ||
7849 | This string, when output subsequently by @code{assemble_name}, should | |
4977bab6 | 7850 | produce the output that @code{(*targetm.asm_out.internal_label)} would produce |
feca2ed3 JW |
7851 | with the same @var{prefix} and @var{num}. |
7852 | ||
7853 | If the string begins with @samp{*}, then @code{assemble_name} will | |
7854 | output the rest of the string unchanged. It is often convenient for | |
7855 | @code{ASM_GENERATE_INTERNAL_LABEL} to use @samp{*} in this way. If the | |
7856 | string doesn't start with @samp{*}, then @code{ASM_OUTPUT_LABELREF} gets | |
7857 | to output the string, and may change it. (Of course, | |
7858 | @code{ASM_OUTPUT_LABELREF} is also part of your machine description, so | |
7859 | you should know what it does on your machine.) | |
a2c4f8e0 | 7860 | @end defmac |
feca2ed3 | 7861 | |
a2c4f8e0 | 7862 | @defmac ASM_FORMAT_PRIVATE_NAME (@var{outvar}, @var{name}, @var{number}) |
feca2ed3 JW |
7863 | A C expression to assign to @var{outvar} (which is a variable of type |
7864 | @code{char *}) a newly allocated string made from the string | |
7865 | @var{name} and the number @var{number}, with some suitable punctuation | |
7866 | added. Use @code{alloca} to get space for the string. | |
7867 | ||
7868 | The string will be used as an argument to @code{ASM_OUTPUT_LABELREF} to | |
7869 | produce an assembler label for an internal static variable whose name is | |
7870 | @var{name}. Therefore, the string must be such as to result in valid | |
7871 | assembler code. The argument @var{number} is different each time this | |
7872 | macro is executed; it prevents conflicts between similarly-named | |
7873 | internal static variables in different scopes. | |
7874 | ||
7875 | Ideally this string should not be a valid C identifier, to prevent any | |
7876 | conflict with the user's own symbols. Most assemblers allow periods | |
7877 | or percent signs in assembler symbols; putting at least one of these | |
7878 | between the name and the number will suffice. | |
7879 | ||
4977bab6 ZW |
7880 | If this macro is not defined, a default definition will be provided |
7881 | which is correct for most systems. | |
a2c4f8e0 | 7882 | @end defmac |
4977bab6 | 7883 | |
a2c4f8e0 | 7884 | @defmac ASM_OUTPUT_DEF (@var{stream}, @var{name}, @var{value}) |
feca2ed3 JW |
7885 | A C statement to output to the stdio stream @var{stream} assembler code |
7886 | which defines (equates) the symbol @var{name} to have the value @var{value}. | |
7887 | ||
203cb4ef | 7888 | @findex SET_ASM_OP |
aee96fe9 | 7889 | If @code{SET_ASM_OP} is defined, a default definition is provided which is |
feca2ed3 | 7890 | correct for most systems. |
a2c4f8e0 | 7891 | @end defmac |
810e3c45 | 7892 | |
a2c4f8e0 | 7893 | @defmac ASM_OUTPUT_DEF_FROM_DECLS (@var{stream}, @var{decl_of_name}, @var{decl_of_value}) |
e4faf1eb | 7894 | A C statement to output to the stdio stream @var{stream} assembler code |
3b7a2e58 | 7895 | which defines (equates) the symbol whose tree node is @var{decl_of_name} |
e4faf1eb NC |
7896 | to have the value of the tree node @var{decl_of_value}. This macro will |
7897 | be used in preference to @samp{ASM_OUTPUT_DEF} if it is defined and if | |
7898 | the tree nodes are available. | |
7899 | ||
203cb4ef | 7900 | @findex SET_ASM_OP |
aee96fe9 | 7901 | If @code{SET_ASM_OP} is defined, a default definition is provided which is |
956d6950 | 7902 | correct for most systems. |
a2c4f8e0 | 7903 | @end defmac |
956d6950 | 7904 | |
083b6717 JDA |
7905 | @defmac TARGET_DEFERRED_OUTPUT_DEFS (@var{decl_of_name}, @var{decl_of_value}) |
7906 | A C statement that evaluates to true if the assembler code which defines | |
7907 | (equates) the symbol whose tree node is @var{decl_of_name} to have the value | |
7908 | of the tree node @var{decl_of_value} should be emitted near the end of the | |
7909 | current compilation unit. The default is to not defer output of defines. | |
7910 | This macro affects defines output by @samp{ASM_OUTPUT_DEF} and | |
7911 | @samp{ASM_OUTPUT_DEF_FROM_DECLS}. | |
7912 | @end defmac | |
7913 | ||
a2c4f8e0 | 7914 | @defmac ASM_OUTPUT_WEAK_ALIAS (@var{stream}, @var{name}, @var{value}) |
810e3c45 JM |
7915 | A C statement to output to the stdio stream @var{stream} assembler code |
7916 | which defines (equates) the weak symbol @var{name} to have the value | |
3aa8ab7b L |
7917 | @var{value}. If @var{value} is @code{NULL}, it defines @var{name} as |
7918 | an undefined weak symbol. | |
810e3c45 JM |
7919 | |
7920 | Define this macro if the target only supports weak aliases; define | |
aee96fe9 | 7921 | @code{ASM_OUTPUT_DEF} instead if possible. |
a2c4f8e0 | 7922 | @end defmac |
810e3c45 | 7923 | |
a2c4f8e0 | 7924 | @defmac OBJC_GEN_METHOD_LABEL (@var{buf}, @var{is_inst}, @var{class_name}, @var{cat_name}, @var{sel_name}) |
feca2ed3 | 7925 | Define this macro to override the default assembler names used for |
2147b154 | 7926 | Objective-C methods. |
feca2ed3 JW |
7927 | |
7928 | The default name is a unique method number followed by the name of the | |
7929 | class (e.g.@: @samp{_1_Foo}). For methods in categories, the name of | |
7930 | the category is also included in the assembler name (e.g.@: | |
7931 | @samp{_1_Foo_Bar}). | |
7932 | ||
7933 | These names are safe on most systems, but make debugging difficult since | |
7934 | the method's selector is not present in the name. Therefore, particular | |
7935 | systems define other ways of computing names. | |
7936 | ||
7937 | @var{buf} is an expression of type @code{char *} which gives you a | |
7938 | buffer in which to store the name; its length is as long as | |
7939 | @var{class_name}, @var{cat_name} and @var{sel_name} put together, plus | |
7940 | 50 characters extra. | |
7941 | ||
7942 | The argument @var{is_inst} specifies whether the method is an instance | |
7943 | method or a class method; @var{class_name} is the name of the class; | |
59d42021 | 7944 | @var{cat_name} is the name of the category (or @code{NULL} if the method is not |
feca2ed3 JW |
7945 | in a category); and @var{sel_name} is the name of the selector. |
7946 | ||
7947 | On systems where the assembler can handle quoted names, you can use this | |
7948 | macro to provide more human-readable names. | |
a2c4f8e0 | 7949 | @end defmac |
28df0b5a | 7950 | |
a2c4f8e0 | 7951 | @defmac ASM_DECLARE_CLASS_REFERENCE (@var{stream}, @var{name}) |
f60b945b SS |
7952 | A C statement (sans semicolon) to output to the stdio stream |
7953 | @var{stream} commands to declare that the label @var{name} is an | |
7954 | Objective-C class reference. This is only needed for targets whose | |
7955 | linkers have special support for NeXT-style runtimes. | |
a2c4f8e0 | 7956 | @end defmac |
f60b945b | 7957 | |
a2c4f8e0 | 7958 | @defmac ASM_DECLARE_UNRESOLVED_REFERENCE (@var{stream}, @var{name}) |
28df0b5a SS |
7959 | A C statement (sans semicolon) to output to the stdio stream |
7960 | @var{stream} commands to declare that the label @var{name} is an | |
7961 | unresolved Objective-C class reference. This is only needed for targets | |
7962 | whose linkers have special support for NeXT-style runtimes. | |
a2c4f8e0 | 7963 | @end defmac |
feca2ed3 JW |
7964 | |
7965 | @node Initialization | |
7966 | @subsection How Initialization Functions Are Handled | |
7967 | @cindex initialization routines | |
7968 | @cindex termination routines | |
7969 | @cindex constructors, output of | |
7970 | @cindex destructors, output of | |
7971 | ||
7972 | The compiled code for certain languages includes @dfn{constructors} | |
7973 | (also called @dfn{initialization routines})---functions to initialize | |
7974 | data in the program when the program is started. These functions need | |
7975 | to be called before the program is ``started''---that is to say, before | |
7976 | @code{main} is called. | |
7977 | ||
7978 | Compiling some languages generates @dfn{destructors} (also called | |
7979 | @dfn{termination routines}) that should be called when the program | |
7980 | terminates. | |
7981 | ||
7982 | To make the initialization and termination functions work, the compiler | |
7983 | must output something in the assembler code to cause those functions to | |
7984 | be called at the appropriate time. When you port the compiler to a new | |
7985 | system, you need to specify how to do this. | |
7986 | ||
7987 | There are two major ways that GCC currently supports the execution of | |
7988 | initialization and termination functions. Each way has two variants. | |
7989 | Much of the structure is common to all four variations. | |
7990 | ||
7991 | @findex __CTOR_LIST__ | |
7992 | @findex __DTOR_LIST__ | |
7993 | The linker must build two lists of these functions---a list of | |
7994 | initialization functions, called @code{__CTOR_LIST__}, and a list of | |
7995 | termination functions, called @code{__DTOR_LIST__}. | |
7996 | ||
7997 | Each list always begins with an ignored function pointer (which may hold | |
7998 | 0, @minus{}1, or a count of the function pointers after it, depending on | |
7999 | the environment). This is followed by a series of zero or more function | |
8000 | pointers to constructors (or destructors), followed by a function | |
8001 | pointer containing zero. | |
8002 | ||
8003 | Depending on the operating system and its executable file format, either | |
8004 | @file{crtstuff.c} or @file{libgcc2.c} traverses these lists at startup | |
8005 | time and exit time. Constructors are called in reverse order of the | |
8006 | list; destructors in forward order. | |
8007 | ||
8008 | The best way to handle static constructors works only for object file | |
8009 | formats which provide arbitrarily-named sections. A section is set | |
8010 | aside for a list of constructors, and another for a list of destructors. | |
8011 | Traditionally these are called @samp{.ctors} and @samp{.dtors}. Each | |
8012 | object file that defines an initialization function also puts a word in | |
8013 | the constructor section to point to that function. The linker | |
8014 | accumulates all these words into one contiguous @samp{.ctors} section. | |
8015 | Termination functions are handled similarly. | |
8016 | ||
2cc07db4 RH |
8017 | This method will be chosen as the default by @file{target-def.h} if |
8018 | @code{TARGET_ASM_NAMED_SECTION} is defined. A target that does not | |
f282ffb3 | 8019 | support arbitrary sections, but does support special designated |
2cc07db4 RH |
8020 | constructor and destructor sections may define @code{CTORS_SECTION_ASM_OP} |
8021 | and @code{DTORS_SECTION_ASM_OP} to achieve the same effect. | |
feca2ed3 JW |
8022 | |
8023 | When arbitrary sections are available, there are two variants, depending | |
8024 | upon how the code in @file{crtstuff.c} is called. On systems that | |
2cc07db4 | 8025 | support a @dfn{.init} section which is executed at program startup, |
feca2ed3 | 8026 | parts of @file{crtstuff.c} are compiled into that section. The |
05739753 | 8027 | program is linked by the @command{gcc} driver like this: |
feca2ed3 | 8028 | |
3ab51846 | 8029 | @smallexample |
2cc07db4 | 8030 | ld -o @var{output_file} crti.o crtbegin.o @dots{} -lgcc crtend.o crtn.o |
3ab51846 | 8031 | @end smallexample |
feca2ed3 | 8032 | |
2cc07db4 RH |
8033 | The prologue of a function (@code{__init}) appears in the @code{.init} |
8034 | section of @file{crti.o}; the epilogue appears in @file{crtn.o}. Likewise | |
8035 | for the function @code{__fini} in the @dfn{.fini} section. Normally these | |
8036 | files are provided by the operating system or by the GNU C library, but | |
8037 | are provided by GCC for a few targets. | |
8038 | ||
8039 | The objects @file{crtbegin.o} and @file{crtend.o} are (for most targets) | |
8040 | compiled from @file{crtstuff.c}. They contain, among other things, code | |
8041 | fragments within the @code{.init} and @code{.fini} sections that branch | |
8042 | to routines in the @code{.text} section. The linker will pull all parts | |
8043 | of a section together, which results in a complete @code{__init} function | |
8044 | that invokes the routines we need at startup. | |
feca2ed3 JW |
8045 | |
8046 | To use this variant, you must define the @code{INIT_SECTION_ASM_OP} | |
8047 | macro properly. | |
8048 | ||
2cc07db4 RH |
8049 | If no init section is available, when GCC compiles any function called |
8050 | @code{main} (or more accurately, any function designated as a program | |
8051 | entry point by the language front end calling @code{expand_main_function}), | |
8052 | it inserts a procedure call to @code{__main} as the first executable code | |
8053 | after the function prologue. The @code{__main} function is defined | |
8054 | in @file{libgcc2.c} and runs the global constructors. | |
feca2ed3 JW |
8055 | |
8056 | In file formats that don't support arbitrary sections, there are again | |
8057 | two variants. In the simplest variant, the GNU linker (GNU @code{ld}) | |
8058 | and an `a.out' format must be used. In this case, | |
2cc07db4 | 8059 | @code{TARGET_ASM_CONSTRUCTOR} is defined to produce a @code{.stabs} |
feca2ed3 JW |
8060 | entry of type @samp{N_SETT}, referencing the name @code{__CTOR_LIST__}, |
8061 | and with the address of the void function containing the initialization | |
8062 | code as its value. The GNU linker recognizes this as a request to add | |
2cc07db4 | 8063 | the value to a @dfn{set}; the values are accumulated, and are eventually |
feca2ed3 JW |
8064 | placed in the executable as a vector in the format described above, with |
8065 | a leading (ignored) count and a trailing zero element. | |
2cc07db4 | 8066 | @code{TARGET_ASM_DESTRUCTOR} is handled similarly. Since no init |
feca2ed3 JW |
8067 | section is available, the absence of @code{INIT_SECTION_ASM_OP} causes |
8068 | the compilation of @code{main} to call @code{__main} as above, starting | |
8069 | the initialization process. | |
8070 | ||
8071 | The last variant uses neither arbitrary sections nor the GNU linker. | |
8072 | This is preferable when you want to do dynamic linking and when using | |
161d7b59 | 8073 | file formats which the GNU linker does not support, such as `ECOFF'@. In |
2cc07db4 RH |
8074 | this case, @code{TARGET_HAVE_CTORS_DTORS} is false, initialization and |
8075 | termination functions are recognized simply by their names. This requires | |
8076 | an extra program in the linkage step, called @command{collect2}. This program | |
8077 | pretends to be the linker, for use with GCC; it does its job by running | |
8078 | the ordinary linker, but also arranges to include the vectors of | |
8079 | initialization and termination functions. These functions are called | |
8080 | via @code{__main} as described above. In order to use this method, | |
8081 | @code{use_collect2} must be defined in the target in @file{config.gcc}. | |
feca2ed3 JW |
8082 | |
8083 | @ifinfo | |
8084 | The following section describes the specific macros that control and | |
8085 | customize the handling of initialization and termination functions. | |
8086 | @end ifinfo | |
8087 | ||
8088 | @node Macros for Initialization | |
8089 | @subsection Macros Controlling Initialization Routines | |
8090 | ||
8091 | Here are the macros that control how the compiler handles initialization | |
8092 | and termination functions: | |
8093 | ||
a2c4f8e0 | 8094 | @defmac INIT_SECTION_ASM_OP |
047c1c92 HPN |
8095 | If defined, a C string constant, including spacing, for the assembler |
8096 | operation to identify the following data as initialization code. If not | |
8097 | defined, GCC will assume such a section does not exist. When you are | |
8098 | using special sections for initialization and termination functions, this | |
8099 | macro also controls how @file{crtstuff.c} and @file{libgcc2.c} arrange to | |
8100 | run the initialization functions. | |
a2c4f8e0 | 8101 | @end defmac |
feca2ed3 | 8102 | |
a2c4f8e0 | 8103 | @defmac HAS_INIT_SECTION |
feca2ed3 | 8104 | If defined, @code{main} will not call @code{__main} as described above. |
2cc07db4 RH |
8105 | This macro should be defined for systems that control start-up code |
8106 | on a symbol-by-symbol basis, such as OSF/1, and should not | |
8107 | be defined explicitly for systems that support @code{INIT_SECTION_ASM_OP}. | |
a2c4f8e0 | 8108 | @end defmac |
feca2ed3 | 8109 | |
a2c4f8e0 | 8110 | @defmac LD_INIT_SWITCH |
feca2ed3 JW |
8111 | If defined, a C string constant for a switch that tells the linker that |
8112 | the following symbol is an initialization routine. | |
a2c4f8e0 | 8113 | @end defmac |
feca2ed3 | 8114 | |
a2c4f8e0 | 8115 | @defmac LD_FINI_SWITCH |
feca2ed3 JW |
8116 | If defined, a C string constant for a switch that tells the linker that |
8117 | the following symbol is a finalization routine. | |
a2c4f8e0 | 8118 | @end defmac |
feca2ed3 | 8119 | |
a2c4f8e0 | 8120 | @defmac COLLECT_SHARED_INIT_FUNC (@var{stream}, @var{func}) |
414e05cf RE |
8121 | If defined, a C statement that will write a function that can be |
8122 | automatically called when a shared library is loaded. The function | |
8123 | should call @var{func}, which takes no arguments. If not defined, and | |
8124 | the object format requires an explicit initialization function, then a | |
172270b3 | 8125 | function called @code{_GLOBAL__DI} will be generated. |
414e05cf RE |
8126 | |
8127 | This function and the following one are used by collect2 when linking a | |
f282ffb3 | 8128 | shared library that needs constructors or destructors, or has DWARF2 |
414e05cf | 8129 | exception tables embedded in the code. |
a2c4f8e0 | 8130 | @end defmac |
414e05cf | 8131 | |
a2c4f8e0 | 8132 | @defmac COLLECT_SHARED_FINI_FUNC (@var{stream}, @var{func}) |
414e05cf RE |
8133 | If defined, a C statement that will write a function that can be |
8134 | automatically called when a shared library is unloaded. The function | |
8135 | should call @var{func}, which takes no arguments. If not defined, and | |
8136 | the object format requires an explicit finalization function, then a | |
172270b3 | 8137 | function called @code{_GLOBAL__DD} will be generated. |
a2c4f8e0 | 8138 | @end defmac |
414e05cf | 8139 | |
a2c4f8e0 | 8140 | @defmac INVOKE__main |
feca2ed3 JW |
8141 | If defined, @code{main} will call @code{__main} despite the presence of |
8142 | @code{INIT_SECTION_ASM_OP}. This macro should be defined for systems | |
8143 | where the init section is not actually run automatically, but is still | |
8144 | useful for collecting the lists of constructors and destructors. | |
a2c4f8e0 | 8145 | @end defmac |
feca2ed3 | 8146 | |
a2c4f8e0 | 8147 | @defmac SUPPORTS_INIT_PRIORITY |
ea4f1fce JO |
8148 | If nonzero, the C++ @code{init_priority} attribute is supported and the |
8149 | compiler should emit instructions to control the order of initialization | |
8150 | of objects. If zero, the compiler will issue an error message upon | |
8151 | encountering an @code{init_priority} attribute. | |
a2c4f8e0 | 8152 | @end defmac |
2cc07db4 RH |
8153 | |
8154 | @deftypefn {Target Hook} bool TARGET_HAVE_CTORS_DTORS | |
8155 | This value is true if the target supports some ``native'' method of | |
8156 | collecting constructors and destructors to be run at startup and exit. | |
8157 | It is false if we must use @command{collect2}. | |
8158 | @end deftypefn | |
8159 | ||
8160 | @deftypefn {Target Hook} void TARGET_ASM_CONSTRUCTOR (rtx @var{symbol}, int @var{priority}) | |
8161 | If defined, a function that outputs assembler code to arrange to call | |
8162 | the function referenced by @var{symbol} at initialization time. | |
ea4f1fce | 8163 | |
2cc07db4 RH |
8164 | Assume that @var{symbol} is a @code{SYMBOL_REF} for a function taking |
8165 | no arguments and with no return value. If the target supports initialization | |
8166 | priorities, @var{priority} is a value between 0 and @code{MAX_INIT_PRIORITY}; | |
8167 | otherwise it must be @code{DEFAULT_INIT_PRIORITY}. | |
8168 | ||
14976c58 | 8169 | If this macro is not defined by the target, a suitable default will |
2cc07db4 RH |
8170 | be chosen if (1) the target supports arbitrary section names, (2) the |
8171 | target defines @code{CTORS_SECTION_ASM_OP}, or (3) @code{USE_COLLECT2} | |
8172 | is not defined. | |
8173 | @end deftypefn | |
8174 | ||
8175 | @deftypefn {Target Hook} void TARGET_ASM_DESTRUCTOR (rtx @var{symbol}, int @var{priority}) | |
8176 | This is like @code{TARGET_ASM_CONSTRUCTOR} but used for termination | |
feca2ed3 | 8177 | functions rather than initialization functions. |
2cc07db4 | 8178 | @end deftypefn |
14686fcd | 8179 | |
2cc07db4 RH |
8180 | If @code{TARGET_HAVE_CTORS_DTORS} is true, the initialization routine |
8181 | generated for the generated object file will have static linkage. | |
feca2ed3 | 8182 | |
2cc07db4 RH |
8183 | If your system uses @command{collect2} as the means of processing |
8184 | constructors, then that program normally uses @command{nm} to scan | |
8185 | an object file for constructor functions to be called. | |
14686fcd | 8186 | |
4a023207 | 8187 | On certain kinds of systems, you can define this macro to make |
2cc07db4 | 8188 | @command{collect2} work faster (and, in some cases, make it work at all): |
feca2ed3 | 8189 | |
a2c4f8e0 | 8190 | @defmac OBJECT_FORMAT_COFF |
feca2ed3 | 8191 | Define this macro if the system uses COFF (Common Object File Format) |
2cc07db4 | 8192 | object files, so that @command{collect2} can assume this format and scan |
feca2ed3 | 8193 | object files directly for dynamic constructor/destructor functions. |
feca2ed3 | 8194 | |
4a023207 | 8195 | This macro is effective only in a native compiler; @command{collect2} as |
2cc07db4 | 8196 | part of a cross compiler always uses @command{nm} for the target machine. |
a2c4f8e0 | 8197 | @end defmac |
feca2ed3 | 8198 | |
a2c4f8e0 | 8199 | @defmac REAL_NM_FILE_NAME |
feca2ed3 | 8200 | Define this macro as a C string constant containing the file name to use |
2cc07db4 RH |
8201 | to execute @command{nm}. The default is to search the path normally for |
8202 | @command{nm}. | |
feca2ed3 JW |
8203 | |
8204 | If your system supports shared libraries and has a program to list the | |
8205 | dynamic dependencies of a given library or executable, you can define | |
8206 | these macros to enable support for running initialization and | |
8207 | termination functions in shared libraries: | |
a2c4f8e0 | 8208 | @end defmac |
feca2ed3 | 8209 | |
a2c4f8e0 | 8210 | @defmac LDD_SUFFIX |
2cc07db4 RH |
8211 | Define this macro to a C string constant containing the name of the program |
8212 | which lists dynamic dependencies, like @command{"ldd"} under SunOS 4. | |
a2c4f8e0 | 8213 | @end defmac |
feca2ed3 | 8214 | |
a2c4f8e0 | 8215 | @defmac PARSE_LDD_OUTPUT (@var{ptr}) |
feca2ed3 | 8216 | Define this macro to be C code that extracts filenames from the output |
aee96fe9 | 8217 | of the program denoted by @code{LDD_SUFFIX}. @var{ptr} is a variable |
feca2ed3 JW |
8218 | of type @code{char *} that points to the beginning of a line of output |
8219 | from @code{LDD_SUFFIX}. If the line lists a dynamic dependency, the | |
aee96fe9 JM |
8220 | code must advance @var{ptr} to the beginning of the filename on that |
8221 | line. Otherwise, it must set @var{ptr} to @code{NULL}. | |
a2c4f8e0 | 8222 | @end defmac |
feca2ed3 | 8223 | |
881466d8 JDA |
8224 | @defmac SHLIB_SUFFIX |
8225 | Define this macro to a C string constant containing the default shared | |
8226 | library extension of the target (e.g., @samp{".so"}). @command{collect2} | |
8227 | strips version information after this suffix when generating global | |
8228 | constructor and destructor names. This define is only needed on targets | |
8229 | that use @command{collect2} to process constructors and destructors. | |
8230 | @end defmac | |
8231 | ||
feca2ed3 JW |
8232 | @node Instruction Output |
8233 | @subsection Output of Assembler Instructions | |
8234 | ||
8235 | @c prevent bad page break with this line | |
8236 | This describes assembler instruction output. | |
8237 | ||
a2c4f8e0 | 8238 | @defmac REGISTER_NAMES |
feca2ed3 JW |
8239 | A C initializer containing the assembler's names for the machine |
8240 | registers, each one as a C string constant. This is what translates | |
8241 | register numbers in the compiler into assembler language. | |
a2c4f8e0 | 8242 | @end defmac |
feca2ed3 | 8243 | |
a2c4f8e0 | 8244 | @defmac ADDITIONAL_REGISTER_NAMES |
feca2ed3 JW |
8245 | If defined, a C initializer for an array of structures containing a name |
8246 | and a register number. This macro defines additional names for hard | |
8247 | registers, thus allowing the @code{asm} option in declarations to refer | |
8248 | to registers using alternate names. | |
a2c4f8e0 | 8249 | @end defmac |
feca2ed3 | 8250 | |
a2c4f8e0 | 8251 | @defmac ASM_OUTPUT_OPCODE (@var{stream}, @var{ptr}) |
feca2ed3 JW |
8252 | Define this macro if you are using an unusual assembler that |
8253 | requires different names for the machine instructions. | |
8254 | ||
8255 | The definition is a C statement or statements which output an | |
8256 | assembler instruction opcode to the stdio stream @var{stream}. The | |
8257 | macro-operand @var{ptr} is a variable of type @code{char *} which | |
8258 | points to the opcode name in its ``internal'' form---the form that is | |
8259 | written in the machine description. The definition should output the | |
8260 | opcode name to @var{stream}, performing any translation you desire, and | |
8261 | increment the variable @var{ptr} to point at the end of the opcode | |
8262 | so that it will not be output twice. | |
8263 | ||
8264 | In fact, your macro definition may process less than the entire opcode | |
8265 | name, or more than the opcode name; but if you want to process text | |
8266 | that includes @samp{%}-sequences to substitute operands, you must take | |
8267 | care of the substitution yourself. Just be sure to increment | |
8268 | @var{ptr} over whatever text should not be output normally. | |
8269 | ||
37bef197 | 8270 | @findex recog_data.operand |
feca2ed3 | 8271 | If you need to look at the operand values, they can be found as the |
37bef197 | 8272 | elements of @code{recog_data.operand}. |
feca2ed3 JW |
8273 | |
8274 | If the macro definition does nothing, the instruction is output | |
8275 | in the usual way. | |
a2c4f8e0 | 8276 | @end defmac |
feca2ed3 | 8277 | |
a2c4f8e0 | 8278 | @defmac FINAL_PRESCAN_INSN (@var{insn}, @var{opvec}, @var{noperands}) |
feca2ed3 JW |
8279 | If defined, a C statement to be executed just prior to the output of |
8280 | assembler code for @var{insn}, to modify the extracted operands so | |
8281 | they will be output differently. | |
8282 | ||
8283 | Here the argument @var{opvec} is the vector containing the operands | |
8284 | extracted from @var{insn}, and @var{noperands} is the number of | |
8285 | elements of the vector which contain meaningful data for this insn. | |
8286 | The contents of this vector are what will be used to convert the insn | |
8287 | template into assembler code, so you can change the assembler output | |
8288 | by changing the contents of the vector. | |
8289 | ||
8290 | This macro is useful when various assembler syntaxes share a single | |
8291 | file of instruction patterns; by defining this macro differently, you | |
8292 | can cause a large class of instructions to be output differently (such | |
8293 | as with rearranged operands). Naturally, variations in assembler | |
8294 | syntax affecting individual insn patterns ought to be handled by | |
8295 | writing conditional output routines in those patterns. | |
8296 | ||
8297 | If this macro is not defined, it is equivalent to a null statement. | |
a2c4f8e0 | 8298 | @end defmac |
feca2ed3 | 8299 | |
1afc5373 CF |
8300 | @deftypefn {Target Hook} void TARGET_ASM_FINAL_POSTSCAN_INSN (FILE *@var{FILE}, rtx @var{insn}, rtx *@var{opvec}, int @var{noperands}) |
8301 | If defined, this target hook is a function which is executed just after the | |
8302 | output of assembler code for @var{insn}, to change the mode of the assembler | |
8303 | if necessary. | |
8304 | ||
8305 | Here the argument @var{opvec} is the vector containing the operands | |
8306 | extracted from @var{insn}, and @var{noperands} is the number of | |
8307 | elements of the vector which contain meaningful data for this insn. | |
8308 | The contents of this vector are what was used to convert the insn | |
8309 | template into assembler code, so you can change the assembler mode | |
8310 | by checking the contents of the vector. | |
8311 | @end deftypefn | |
8312 | ||
a2c4f8e0 | 8313 | @defmac PRINT_OPERAND (@var{stream}, @var{x}, @var{code}) |
feca2ed3 JW |
8314 | A C compound statement to output to stdio stream @var{stream} the |
8315 | assembler syntax for an instruction operand @var{x}. @var{x} is an | |
8316 | RTL expression. | |
8317 | ||
8318 | @var{code} is a value that can be used to specify one of several ways | |
8319 | of printing the operand. It is used when identical operands must be | |
8320 | printed differently depending on the context. @var{code} comes from | |
8321 | the @samp{%} specification that was used to request printing of the | |
8322 | operand. If the specification was just @samp{%@var{digit}} then | |
8323 | @var{code} is 0; if the specification was @samp{%@var{ltr} | |
8324 | @var{digit}} then @var{code} is the ASCII code for @var{ltr}. | |
8325 | ||
8326 | @findex reg_names | |
8327 | If @var{x} is a register, this macro should print the register's name. | |
8328 | The names can be found in an array @code{reg_names} whose type is | |
8329 | @code{char *[]}. @code{reg_names} is initialized from | |
8330 | @code{REGISTER_NAMES}. | |
8331 | ||
8332 | When the machine description has a specification @samp{%@var{punct}} | |
8333 | (a @samp{%} followed by a punctuation character), this macro is called | |
8334 | with a null pointer for @var{x} and the punctuation character for | |
8335 | @var{code}. | |
a2c4f8e0 | 8336 | @end defmac |
feca2ed3 | 8337 | |
a2c4f8e0 | 8338 | @defmac PRINT_OPERAND_PUNCT_VALID_P (@var{code}) |
feca2ed3 JW |
8339 | A C expression which evaluates to true if @var{code} is a valid |
8340 | punctuation character for use in the @code{PRINT_OPERAND} macro. If | |
8341 | @code{PRINT_OPERAND_PUNCT_VALID_P} is not defined, it means that no | |
8342 | punctuation characters (except for the standard one, @samp{%}) are used | |
8343 | in this way. | |
a2c4f8e0 | 8344 | @end defmac |
feca2ed3 | 8345 | |
a2c4f8e0 | 8346 | @defmac PRINT_OPERAND_ADDRESS (@var{stream}, @var{x}) |
feca2ed3 JW |
8347 | A C compound statement to output to stdio stream @var{stream} the |
8348 | assembler syntax for an instruction operand that is a memory reference | |
8349 | whose address is @var{x}. @var{x} is an RTL expression. | |
8350 | ||
fb49053f | 8351 | @cindex @code{TARGET_ENCODE_SECTION_INFO} usage |
feca2ed3 | 8352 | On some machines, the syntax for a symbolic address depends on the |
fb49053f RH |
8353 | section that the address refers to. On these machines, define the hook |
8354 | @code{TARGET_ENCODE_SECTION_INFO} to store the information into the | |
a2c4f8e0 ZW |
8355 | @code{symbol_ref}, and then check for it here. @xref{Assembler |
8356 | Format}. | |
8357 | @end defmac | |
feca2ed3 | 8358 | |
feca2ed3 | 8359 | @findex dbr_sequence_length |
a2c4f8e0 | 8360 | @defmac DBR_OUTPUT_SEQEND (@var{file}) |
feca2ed3 JW |
8361 | A C statement, to be executed after all slot-filler instructions have |
8362 | been output. If necessary, call @code{dbr_sequence_length} to | |
8363 | determine the number of slots filled in a sequence (zero if not | |
8364 | currently outputting a sequence), to decide how many no-ops to output, | |
8365 | or whatever. | |
8366 | ||
8367 | Don't define this macro if it has nothing to do, but it is helpful in | |
8368 | reading assembly output if the extent of the delay sequence is made | |
e979f9e8 | 8369 | explicit (e.g.@: with white space). |
a2c4f8e0 | 8370 | @end defmac |
feca2ed3 JW |
8371 | |
8372 | @findex final_sequence | |
8373 | Note that output routines for instructions with delay slots must be | |
e979f9e8 JM |
8374 | prepared to deal with not being output as part of a sequence |
8375 | (i.e.@: when the scheduling pass is not run, or when no slot fillers could be | |
feca2ed3 JW |
8376 | found.) The variable @code{final_sequence} is null when not |
8377 | processing a sequence, otherwise it contains the @code{sequence} rtx | |
8378 | being output. | |
8379 | ||
feca2ed3 | 8380 | @findex asm_fprintf |
a2c4f8e0 ZW |
8381 | @defmac REGISTER_PREFIX |
8382 | @defmacx LOCAL_LABEL_PREFIX | |
8383 | @defmacx USER_LABEL_PREFIX | |
8384 | @defmacx IMMEDIATE_PREFIX | |
feca2ed3 JW |
8385 | If defined, C string expressions to be used for the @samp{%R}, @samp{%L}, |
8386 | @samp{%U}, and @samp{%I} options of @code{asm_fprintf} (see | |
8387 | @file{final.c}). These are useful when a single @file{md} file must | |
8388 | support multiple assembler formats. In that case, the various @file{tm.h} | |
8389 | files can define these macros differently. | |
a2c4f8e0 | 8390 | @end defmac |
feca2ed3 | 8391 | |
a2c4f8e0 | 8392 | @defmac ASM_FPRINTF_EXTENSIONS (@var{file}, @var{argptr}, @var{format}) |
3b7a2e58 | 8393 | If defined this macro should expand to a series of @code{case} |
fe0503ea NC |
8394 | statements which will be parsed inside the @code{switch} statement of |
8395 | the @code{asm_fprintf} function. This allows targets to define extra | |
8396 | printf formats which may useful when generating their assembler | |
4bd0bee9 | 8397 | statements. Note that uppercase letters are reserved for future |
fe0503ea NC |
8398 | generic extensions to asm_fprintf, and so are not available to target |
8399 | specific code. The output file is given by the parameter @var{file}. | |
8400 | The varargs input pointer is @var{argptr} and the rest of the format | |
8401 | string, starting the character after the one that is being switched | |
8402 | upon, is pointed to by @var{format}. | |
a2c4f8e0 | 8403 | @end defmac |
fe0503ea | 8404 | |
a2c4f8e0 | 8405 | @defmac ASSEMBLER_DIALECT |
feca2ed3 JW |
8406 | If your target supports multiple dialects of assembler language (such as |
8407 | different opcodes), define this macro as a C expression that gives the | |
8408 | numeric index of the assembler language dialect to use, with zero as the | |
8409 | first variant. | |
8410 | ||
8411 | If this macro is defined, you may use constructs of the form | |
c237e94a | 8412 | @smallexample |
f282ffb3 | 8413 | @samp{@{option0|option1|option2@dots{}@}} |
c237e94a ZW |
8414 | @end smallexample |
8415 | @noindent | |
8416 | in the output templates of patterns (@pxref{Output Template}) or in the | |
8417 | first argument of @code{asm_fprintf}. This construct outputs | |
8418 | @samp{option0}, @samp{option1}, @samp{option2}, etc., if the value of | |
8419 | @code{ASSEMBLER_DIALECT} is zero, one, two, etc. Any special characters | |
8420 | within these strings retain their usual meaning. If there are fewer | |
8421 | alternatives within the braces than the value of | |
8422 | @code{ASSEMBLER_DIALECT}, the construct outputs nothing. | |
feca2ed3 JW |
8423 | |
8424 | If you do not define this macro, the characters @samp{@{}, @samp{|} and | |
8425 | @samp{@}} do not have any special meaning when used in templates or | |
8426 | operands to @code{asm_fprintf}. | |
8427 | ||
8428 | Define the macros @code{REGISTER_PREFIX}, @code{LOCAL_LABEL_PREFIX}, | |
8429 | @code{USER_LABEL_PREFIX} and @code{IMMEDIATE_PREFIX} if you can express | |
e5e809f4 | 8430 | the variations in assembler language syntax with that mechanism. Define |
feca2ed3 JW |
8431 | @code{ASSEMBLER_DIALECT} and use the @samp{@{option0|option1@}} syntax |
8432 | if the syntax variant are larger and involve such things as different | |
8433 | opcodes or operand order. | |
a2c4f8e0 | 8434 | @end defmac |
feca2ed3 | 8435 | |
a2c4f8e0 | 8436 | @defmac ASM_OUTPUT_REG_PUSH (@var{stream}, @var{regno}) |
feca2ed3 JW |
8437 | A C expression to output to @var{stream} some assembler code |
8438 | which will push hard register number @var{regno} onto the stack. | |
8439 | The code need not be optimal, since this macro is used only when | |
8440 | profiling. | |
a2c4f8e0 | 8441 | @end defmac |
feca2ed3 | 8442 | |
a2c4f8e0 | 8443 | @defmac ASM_OUTPUT_REG_POP (@var{stream}, @var{regno}) |
feca2ed3 JW |
8444 | A C expression to output to @var{stream} some assembler code |
8445 | which will pop hard register number @var{regno} off of the stack. | |
8446 | The code need not be optimal, since this macro is used only when | |
8447 | profiling. | |
a2c4f8e0 | 8448 | @end defmac |
feca2ed3 JW |
8449 | |
8450 | @node Dispatch Tables | |
8451 | @subsection Output of Dispatch Tables | |
8452 | ||
8453 | @c prevent bad page break with this line | |
8454 | This concerns dispatch tables. | |
8455 | ||
feca2ed3 | 8456 | @cindex dispatch table |
a2c4f8e0 | 8457 | @defmac ASM_OUTPUT_ADDR_DIFF_ELT (@var{stream}, @var{body}, @var{value}, @var{rel}) |
feca2ed3 JW |
8458 | A C statement to output to the stdio stream @var{stream} an assembler |
8459 | pseudo-instruction to generate a difference between two labels. | |
8460 | @var{value} and @var{rel} are the numbers of two internal labels. The | |
8461 | definitions of these labels are output using | |
4977bab6 | 8462 | @code{(*targetm.asm_out.internal_label)}, and they must be printed in the same |
feca2ed3 JW |
8463 | way here. For example, |
8464 | ||
3ab51846 | 8465 | @smallexample |
feca2ed3 JW |
8466 | fprintf (@var{stream}, "\t.word L%d-L%d\n", |
8467 | @var{value}, @var{rel}) | |
3ab51846 | 8468 | @end smallexample |
feca2ed3 JW |
8469 | |
8470 | You must provide this macro on machines where the addresses in a | |
f0523f02 | 8471 | dispatch table are relative to the table's own address. If defined, GCC |
161d7b59 | 8472 | will also use this macro on all machines when producing PIC@. |
aee96fe9 | 8473 | @var{body} is the body of the @code{ADDR_DIFF_VEC}; it is provided so that the |
33f7f353 | 8474 | mode and flags can be read. |
a2c4f8e0 | 8475 | @end defmac |
feca2ed3 | 8476 | |
a2c4f8e0 | 8477 | @defmac ASM_OUTPUT_ADDR_VEC_ELT (@var{stream}, @var{value}) |
feca2ed3 JW |
8478 | This macro should be provided on machines where the addresses |
8479 | in a dispatch table are absolute. | |
8480 | ||
8481 | The definition should be a C statement to output to the stdio stream | |
8482 | @var{stream} an assembler pseudo-instruction to generate a reference to | |
8483 | a label. @var{value} is the number of an internal label whose | |
4977bab6 | 8484 | definition is output using @code{(*targetm.asm_out.internal_label)}. |
feca2ed3 JW |
8485 | For example, |
8486 | ||
3ab51846 | 8487 | @smallexample |
feca2ed3 | 8488 | fprintf (@var{stream}, "\t.word L%d\n", @var{value}) |
3ab51846 | 8489 | @end smallexample |
a2c4f8e0 | 8490 | @end defmac |
feca2ed3 | 8491 | |
a2c4f8e0 | 8492 | @defmac ASM_OUTPUT_CASE_LABEL (@var{stream}, @var{prefix}, @var{num}, @var{table}) |
feca2ed3 JW |
8493 | Define this if the label before a jump-table needs to be output |
8494 | specially. The first three arguments are the same as for | |
4977bab6 | 8495 | @code{(*targetm.asm_out.internal_label)}; the fourth argument is the |
feca2ed3 JW |
8496 | jump-table which follows (a @code{jump_insn} containing an |
8497 | @code{addr_vec} or @code{addr_diff_vec}). | |
8498 | ||
8499 | This feature is used on system V to output a @code{swbeg} statement | |
8500 | for the table. | |
8501 | ||
8502 | If this macro is not defined, these labels are output with | |
4977bab6 | 8503 | @code{(*targetm.asm_out.internal_label)}. |
a2c4f8e0 | 8504 | @end defmac |
feca2ed3 | 8505 | |
a2c4f8e0 | 8506 | @defmac ASM_OUTPUT_CASE_END (@var{stream}, @var{num}, @var{table}) |
feca2ed3 JW |
8507 | Define this if something special must be output at the end of a |
8508 | jump-table. The definition should be a C statement to be executed | |
8509 | after the assembler code for the table is written. It should write | |
8510 | the appropriate code to stdio stream @var{stream}. The argument | |
8511 | @var{table} is the jump-table insn, and @var{num} is the label-number | |
8512 | of the preceding label. | |
8513 | ||
8514 | If this macro is not defined, nothing special is output at the end of | |
8515 | the jump-table. | |
a2c4f8e0 | 8516 | @end defmac |
feca2ed3 | 8517 | |
eeab4d81 | 8518 | @deftypefn {Target Hook} void TARGET_ASM_EMIT_UNWIND_LABEL (@var{stream}, @var{decl}, @var{for_eh}, @var{empty}) |
8a36672b | 8519 | This target hook emits a label at the beginning of each FDE@. It |
4746cf84 MA |
8520 | should be defined on targets where FDEs need special labels, and it |
8521 | should write the appropriate label, for the FDE associated with the | |
8522 | function declaration @var{decl}, to the stdio stream @var{stream}. | |
eeab4d81 MS |
8523 | The third argument, @var{for_eh}, is a boolean: true if this is for an |
8524 | exception table. The fourth argument, @var{empty}, is a boolean: | |
8a36672b | 8525 | true if this is a placeholder label for an omitted FDE@. |
4746cf84 MA |
8526 | |
8527 | The default is that FDEs are not given nonlocal labels. | |
8528 | @end deftypefn | |
8529 | ||
083cad55 EC |
8530 | @deftypefn {Target Hook} void TARGET_ASM_EMIT_EXCEPT_TABLE_LABEL (@var{stream}) |
8531 | This target hook emits a label at the beginning of the exception table. | |
8532 | It should be defined on targets where it is desirable for the table | |
8533 | to be broken up according to function. | |
8534 | ||
8535 | The default is that no label is emitted. | |
8536 | @end deftypefn | |
8537 | ||
8538 | @deftypefn {Target Hook} void TARGET_UNWIND_EMIT (FILE * @var{stream}, rtx @var{insn}) | |
951120ea PB |
8539 | This target hook emits and assembly directives required to unwind the |
8540 | given instruction. This is only used when TARGET_UNWIND_INFO is set. | |
8541 | @end deftypefn | |
8542 | ||
02f52e19 | 8543 | @node Exception Region Output |
feca2ed3 JW |
8544 | @subsection Assembler Commands for Exception Regions |
8545 | ||
8546 | @c prevent bad page break with this line | |
8547 | ||
8548 | This describes commands marking the start and the end of an exception | |
8549 | region. | |
8550 | ||
a2c4f8e0 | 8551 | @defmac EH_FRAME_SECTION_NAME |
7c262518 RH |
8552 | If defined, a C string constant for the name of the section containing |
8553 | exception handling frame unwind information. If not defined, GCC will | |
8554 | provide a default definition if the target supports named sections. | |
8555 | @file{crtstuff.c} uses this macro to switch to the appropriate section. | |
0021b564 JM |
8556 | |
8557 | You should define this symbol if your target supports DWARF 2 frame | |
8558 | unwind information and the default definition does not work. | |
a2c4f8e0 | 8559 | @end defmac |
0021b564 | 8560 | |
a2c4f8e0 | 8561 | @defmac EH_FRAME_IN_DATA_SECTION |
02c9b1ca RH |
8562 | If defined, DWARF 2 frame unwind information will be placed in the |
8563 | data section even though the target supports named sections. This | |
8564 | might be necessary, for instance, if the system linker does garbage | |
8565 | collection and sections cannot be marked as not to be collected. | |
8566 | ||
8567 | Do not define this macro unless @code{TARGET_ASM_NAMED_SECTION} is | |
8568 | also defined. | |
a2c4f8e0 | 8569 | @end defmac |
02c9b1ca | 8570 | |
1a35e62d MM |
8571 | @defmac EH_TABLES_CAN_BE_READ_ONLY |
8572 | Define this macro to 1 if your target is such that no frame unwind | |
8573 | information encoding used with non-PIC code will ever require a | |
8574 | runtime relocation, but the linker may not support merging read-only | |
8575 | and read-write sections into a single read-write section. | |
8576 | @end defmac | |
8577 | ||
a2c4f8e0 | 8578 | @defmac MASK_RETURN_ADDR |
aee96fe9 | 8579 | An rtx used to mask the return address found via @code{RETURN_ADDR_RTX}, so |
feca2ed3 | 8580 | that it does not contain any extraneous set bits in it. |
a2c4f8e0 | 8581 | @end defmac |
0021b564 | 8582 | |
a2c4f8e0 | 8583 | @defmac DWARF2_UNWIND_INFO |
0021b564 JM |
8584 | Define this macro to 0 if your target supports DWARF 2 frame unwind |
8585 | information, but it does not yet work with exception handling. | |
8586 | Otherwise, if your target supports this information (if it defines | |
8587 | @samp{INCOMING_RETURN_ADDR_RTX} and either @samp{UNALIGNED_INT_ASM_OP} | |
4f6c2131 | 8588 | or @samp{OBJECT_FORMAT_ELF}), GCC will provide a default definition of 1. |
0021b564 | 8589 | |
5cf58f28 PB |
8590 | If @code{TARGET_UNWIND_INFO} is defined, the target specific unwinder |
8591 | will be used in all cases. Defining this macro will enable the generation | |
8592 | of DWARF 2 frame debugging information. | |
0021b564 | 8593 | |
5cf58f28 PB |
8594 | If @code{TARGET_UNWIND_INFO} is not defined, and this macro is defined to 1, |
8595 | the DWARF 2 unwinder will be the default exception handling mechanism; | |
4f6c2131 EB |
8596 | otherwise, the @code{setjmp}/@code{longjmp}-based scheme will be used by |
8597 | default. | |
a2c4f8e0 | 8598 | @end defmac |
0021b564 | 8599 | |
951120ea PB |
8600 | @defmac TARGET_UNWIND_INFO |
8601 | Define this macro if your target has ABI specified unwind tables. Usually | |
8602 | these will be output by @code{TARGET_UNWIND_EMIT}. | |
8603 | @end defmac | |
8604 | ||
9e3be889 | 8605 | @deftypevr {Target Hook} bool TARGET_UNWIND_TABLES_DEFAULT |
617a1b71 PB |
8606 | This variable should be set to @code{true} if the target ABI requires unwinding |
8607 | tables even when exceptions are not used. | |
9e3be889 | 8608 | @end deftypevr |
617a1b71 | 8609 | |
c14aea87 RO |
8610 | @defmac MUST_USE_SJLJ_EXCEPTIONS |
8611 | This macro need only be defined if @code{DWARF2_UNWIND_INFO} is | |
8612 | runtime-variable. In that case, @file{except.h} cannot correctly | |
4f6c2131 EB |
8613 | determine the corresponding definition of @code{MUST_USE_SJLJ_EXCEPTIONS}, |
8614 | so the target must provide it directly. | |
8615 | @end defmac | |
8616 | ||
8617 | @defmac DONT_USE_BUILTIN_SETJMP | |
8618 | Define this macro to 1 if the @code{setjmp}/@code{longjmp}-based scheme | |
8619 | should use the @code{setjmp}/@code{longjmp} functions from the C library | |
8620 | instead of the @code{__builtin_setjmp}/@code{__builtin_longjmp} machinery. | |
c14aea87 RO |
8621 | @end defmac |
8622 | ||
a2c4f8e0 | 8623 | @defmac DWARF_CIE_DATA_ALIGNMENT |
27c35f4b HPN |
8624 | This macro need only be defined if the target might save registers in the |
8625 | function prologue at an offset to the stack pointer that is not aligned to | |
8626 | @code{UNITS_PER_WORD}. The definition should be the negative minimum | |
8627 | alignment if @code{STACK_GROWS_DOWNWARD} is defined, and the positive | |
8628 | minimum alignment otherwise. @xref{SDB and DWARF}. Only applicable if | |
8629 | the target supports DWARF 2 frame unwind information. | |
a2c4f8e0 | 8630 | @end defmac |
feca2ed3 | 8631 | |
9e3be889 | 8632 | @deftypevr {Target Hook} bool TARGET_TERMINATE_DW2_EH_FRAME_INFO |
7606e68f SS |
8633 | Contains the value true if the target should add a zero word onto the |
8634 | end of a Dwarf-2 frame info section when used for exception handling. | |
8635 | Default value is false if @code{EH_FRAME_SECTION_NAME} is defined, and | |
8636 | true otherwise. | |
9e3be889 | 8637 | @end deftypevr |
7606e68f | 8638 | |
96714395 AH |
8639 | @deftypefn {Target Hook} rtx TARGET_DWARF_REGISTER_SPAN (rtx @var{reg}) |
8640 | Given a register, this hook should return a parallel of registers to | |
8641 | represent where to find the register pieces. Define this hook if the | |
8642 | register and its mode are represented in Dwarf in non-contiguous | |
8643 | locations, or if the register should be represented in more than one | |
8644 | register in Dwarf. Otherwise, this hook should return @code{NULL_RTX}. | |
8645 | If not defined, the default is to return @code{NULL_RTX}. | |
8646 | @end deftypefn | |
8647 | ||
37ea0b7e JM |
8648 | @deftypefn {Target Hook} void TARGET_INIT_DWARF_REG_SIZES_EXTRA (tree @var{address}) |
8649 | If some registers are represented in Dwarf-2 unwind information in | |
8650 | multiple pieces, define this hook to fill in information about the | |
8651 | sizes of those pieces in the table used by the unwinder at runtime. | |
8652 | It will be called by @code{expand_builtin_init_dwarf_reg_sizes} after | |
8653 | filling in a single size corresponding to each hard register; | |
8654 | @var{address} is the address of the table. | |
8655 | @end deftypefn | |
8656 | ||
617a1b71 PB |
8657 | @deftypefn {Target Hook} bool TARGET_ASM_TTYPE (rtx @var{sym}) |
8658 | This hook is used to output a reference from a frame unwinding table to | |
8659 | the type_info object identified by @var{sym}. It should return @code{true} | |
8660 | if the reference was output. Returning @code{false} will cause the | |
8661 | reference to be output using the normal Dwarf2 routines. | |
8662 | @end deftypefn | |
8663 | ||
8664 | @deftypefn {Target Hook} bool TARGET_ARM_EABI_UNWINDER | |
8665 | This hook should be set to @code{true} on targets that use an ARM EABI | |
8666 | based unwinding library, and @code{false} on other targets. This effects | |
8667 | the format of unwinding tables, and how the unwinder in entered after | |
8668 | running a cleanup. The default is @code{false}. | |
8669 | @end deftypefn | |
8670 | ||
feca2ed3 JW |
8671 | @node Alignment Output |
8672 | @subsection Assembler Commands for Alignment | |
8673 | ||
8674 | @c prevent bad page break with this line | |
8675 | This describes commands for alignment. | |
8676 | ||
a2c4f8e0 | 8677 | @defmac JUMP_ALIGN (@var{label}) |
247a370b | 8678 | The alignment (log base 2) to put in front of @var{label}, which is |
f710504c | 8679 | a common destination of jumps and has no fallthru incoming edge. |
25e22dc0 JH |
8680 | |
8681 | This macro need not be defined if you don't want any special alignment | |
8682 | to be done at such a time. Most machine descriptions do not currently | |
8683 | define the macro. | |
efa3896a | 8684 | |
3446405d JH |
8685 | Unless it's necessary to inspect the @var{label} parameter, it is better |
8686 | to set the variable @var{align_jumps} in the target's | |
c21cd8b1 | 8687 | @code{OVERRIDE_OPTIONS}. Otherwise, you should try to honor the user's |
247a370b | 8688 | selection in @var{align_jumps} in a @code{JUMP_ALIGN} implementation. |
a2c4f8e0 | 8689 | @end defmac |
247a370b | 8690 | |
a2c4f8e0 | 8691 | @defmac LABEL_ALIGN_AFTER_BARRIER (@var{label}) |
247a370b JH |
8692 | The alignment (log base 2) to put in front of @var{label}, which follows |
8693 | a @code{BARRIER}. | |
8694 | ||
8695 | This macro need not be defined if you don't want any special alignment | |
8696 | to be done at such a time. Most machine descriptions do not currently | |
8697 | define the macro. | |
a2c4f8e0 | 8698 | @end defmac |
3446405d | 8699 | |
a2c4f8e0 | 8700 | @defmac LABEL_ALIGN_AFTER_BARRIER_MAX_SKIP |
02f52e19 | 8701 | The maximum number of bytes to skip when applying |
efa3896a GK |
8702 | @code{LABEL_ALIGN_AFTER_BARRIER}. This works only if |
8703 | @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined. | |
a2c4f8e0 | 8704 | @end defmac |
efa3896a | 8705 | |
a2c4f8e0 | 8706 | @defmac LOOP_ALIGN (@var{label}) |
fc470718 | 8707 | The alignment (log base 2) to put in front of @var{label}, which follows |
aee96fe9 | 8708 | a @code{NOTE_INSN_LOOP_BEG} note. |
feca2ed3 JW |
8709 | |
8710 | This macro need not be defined if you don't want any special alignment | |
8711 | to be done at such a time. Most machine descriptions do not currently | |
8712 | define the macro. | |
8713 | ||
efa3896a | 8714 | Unless it's necessary to inspect the @var{label} parameter, it is better |
aee96fe9 | 8715 | to set the variable @code{align_loops} in the target's |
c21cd8b1 | 8716 | @code{OVERRIDE_OPTIONS}. Otherwise, you should try to honor the user's |
aee96fe9 | 8717 | selection in @code{align_loops} in a @code{LOOP_ALIGN} implementation. |
a2c4f8e0 | 8718 | @end defmac |
efa3896a | 8719 | |
a2c4f8e0 | 8720 | @defmac LOOP_ALIGN_MAX_SKIP |
efa3896a GK |
8721 | The maximum number of bytes to skip when applying @code{LOOP_ALIGN}. |
8722 | This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined. | |
a2c4f8e0 | 8723 | @end defmac |
efa3896a | 8724 | |
a2c4f8e0 | 8725 | @defmac LABEL_ALIGN (@var{label}) |
fc470718 | 8726 | The alignment (log base 2) to put in front of @var{label}. |
aee96fe9 | 8727 | If @code{LABEL_ALIGN_AFTER_BARRIER} / @code{LOOP_ALIGN} specify a different alignment, |
fc470718 R |
8728 | the maximum of the specified values is used. |
8729 | ||
efa3896a | 8730 | Unless it's necessary to inspect the @var{label} parameter, it is better |
aee96fe9 | 8731 | to set the variable @code{align_labels} in the target's |
c21cd8b1 | 8732 | @code{OVERRIDE_OPTIONS}. Otherwise, you should try to honor the user's |
aee96fe9 | 8733 | selection in @code{align_labels} in a @code{LABEL_ALIGN} implementation. |
a2c4f8e0 | 8734 | @end defmac |
efa3896a | 8735 | |
a2c4f8e0 | 8736 | @defmac LABEL_ALIGN_MAX_SKIP |
efa3896a GK |
8737 | The maximum number of bytes to skip when applying @code{LABEL_ALIGN}. |
8738 | This works only if @code{ASM_OUTPUT_MAX_SKIP_ALIGN} is defined. | |
a2c4f8e0 | 8739 | @end defmac |
efa3896a | 8740 | |
a2c4f8e0 | 8741 | @defmac ASM_OUTPUT_SKIP (@var{stream}, @var{nbytes}) |
feca2ed3 JW |
8742 | A C statement to output to the stdio stream @var{stream} an assembler |
8743 | instruction to advance the location counter by @var{nbytes} bytes. | |
8744 | Those bytes should be zero when loaded. @var{nbytes} will be a C | |
606e938d | 8745 | expression of type @code{unsigned HOST_WIDE_INT}. |
a2c4f8e0 | 8746 | @end defmac |
feca2ed3 | 8747 | |
a2c4f8e0 | 8748 | @defmac ASM_NO_SKIP_IN_TEXT |
feca2ed3 | 8749 | Define this macro if @code{ASM_OUTPUT_SKIP} should not be used in the |
556e0f21 | 8750 | text section because it fails to put zeros in the bytes that are skipped. |
feca2ed3 JW |
8751 | This is true on many Unix systems, where the pseudo--op to skip bytes |
8752 | produces no-op instructions rather than zeros when used in the text | |
8753 | section. | |
a2c4f8e0 | 8754 | @end defmac |
feca2ed3 | 8755 | |
a2c4f8e0 | 8756 | @defmac ASM_OUTPUT_ALIGN (@var{stream}, @var{power}) |
feca2ed3 JW |
8757 | A C statement to output to the stdio stream @var{stream} an assembler |
8758 | command to advance the location counter to a multiple of 2 to the | |
8759 | @var{power} bytes. @var{power} will be a C expression of type @code{int}. | |
a2c4f8e0 | 8760 | @end defmac |
26f63a77 | 8761 | |
a2c4f8e0 | 8762 | @defmac ASM_OUTPUT_ALIGN_WITH_NOP (@var{stream}, @var{power}) |
8e16ab99 SF |
8763 | Like @code{ASM_OUTPUT_ALIGN}, except that the ``nop'' instruction is used |
8764 | for padding, if necessary. | |
a2c4f8e0 | 8765 | @end defmac |
8e16ab99 | 8766 | |
a2c4f8e0 | 8767 | @defmac ASM_OUTPUT_MAX_SKIP_ALIGN (@var{stream}, @var{power}, @var{max_skip}) |
26f63a77 JL |
8768 | A C statement to output to the stdio stream @var{stream} an assembler |
8769 | command to advance the location counter to a multiple of 2 to the | |
8770 | @var{power} bytes, but only if @var{max_skip} or fewer bytes are needed to | |
8771 | satisfy the alignment request. @var{power} and @var{max_skip} will be | |
8772 | a C expression of type @code{int}. | |
a2c4f8e0 | 8773 | @end defmac |
feca2ed3 JW |
8774 | |
8775 | @need 3000 | |
8776 | @node Debugging Info | |
8777 | @section Controlling Debugging Information Format | |
8778 | ||
8779 | @c prevent bad page break with this line | |
8780 | This describes how to specify debugging information. | |
8781 | ||
8782 | @menu | |
8783 | * All Debuggers:: Macros that affect all debugging formats uniformly. | |
8784 | * DBX Options:: Macros enabling specific options in DBX format. | |
8785 | * DBX Hooks:: Hook macros for varying DBX format. | |
8786 | * File Names and DBX:: Macros controlling output of file names in DBX format. | |
8787 | * SDB and DWARF:: Macros for SDB (COFF) and DWARF formats. | |
5f98259a | 8788 | * VMS Debug:: Macros for VMS debug format. |
feca2ed3 JW |
8789 | @end menu |
8790 | ||
8791 | @node All Debuggers | |
8792 | @subsection Macros Affecting All Debugging Formats | |
8793 | ||
8794 | @c prevent bad page break with this line | |
8795 | These macros affect all debugging formats. | |
8796 | ||
a2c4f8e0 | 8797 | @defmac DBX_REGISTER_NUMBER (@var{regno}) |
feca2ed3 | 8798 | A C expression that returns the DBX register number for the compiler |
4617e3b5 KG |
8799 | register number @var{regno}. In the default macro provided, the value |
8800 | of this expression will be @var{regno} itself. But sometimes there are | |
8801 | some registers that the compiler knows about and DBX does not, or vice | |
8802 | versa. In such cases, some register may need to have one number in the | |
8803 | compiler and another for DBX@. | |
feca2ed3 | 8804 | |
a3a15b4d | 8805 | If two registers have consecutive numbers inside GCC, and they can be |
feca2ed3 JW |
8806 | used as a pair to hold a multiword value, then they @emph{must} have |
8807 | consecutive numbers after renumbering with @code{DBX_REGISTER_NUMBER}. | |
8808 | Otherwise, debuggers will be unable to access such a pair, because they | |
8809 | expect register pairs to be consecutive in their own numbering scheme. | |
8810 | ||
8811 | If you find yourself defining @code{DBX_REGISTER_NUMBER} in way that | |
8812 | does not preserve register pairs, then what you must do instead is | |
8813 | redefine the actual register numbering scheme. | |
a2c4f8e0 | 8814 | @end defmac |
feca2ed3 | 8815 | |
a2c4f8e0 | 8816 | @defmac DEBUGGER_AUTO_OFFSET (@var{x}) |
feca2ed3 JW |
8817 | A C expression that returns the integer offset value for an automatic |
8818 | variable having address @var{x} (an RTL expression). The default | |
8819 | computation assumes that @var{x} is based on the frame-pointer and | |
8820 | gives the offset from the frame-pointer. This is required for targets | |
8821 | that produce debugging output for DBX or COFF-style debugging output | |
8822 | for SDB and allow the frame-pointer to be eliminated when the | |
630d3d5a | 8823 | @option{-g} options is used. |
a2c4f8e0 | 8824 | @end defmac |
feca2ed3 | 8825 | |
a2c4f8e0 | 8826 | @defmac DEBUGGER_ARG_OFFSET (@var{offset}, @var{x}) |
feca2ed3 JW |
8827 | A C expression that returns the integer offset value for an argument |
8828 | having address @var{x} (an RTL expression). The nominal offset is | |
8829 | @var{offset}. | |
a2c4f8e0 | 8830 | @end defmac |
feca2ed3 | 8831 | |
a2c4f8e0 | 8832 | @defmac PREFERRED_DEBUGGING_TYPE |
a3a15b4d | 8833 | A C expression that returns the type of debugging output GCC should |
630d3d5a | 8834 | produce when the user specifies just @option{-g}. Define |
a3a15b4d | 8835 | this if you have arranged for GCC to support more than one format of |
e5e809f4 | 8836 | debugging output. Currently, the allowable values are @code{DBX_DEBUG}, |
5f98259a RK |
8837 | @code{SDB_DEBUG}, @code{DWARF_DEBUG}, @code{DWARF2_DEBUG}, |
8838 | @code{XCOFF_DEBUG}, @code{VMS_DEBUG}, and @code{VMS_AND_DWARF2_DEBUG}. | |
feca2ed3 | 8839 | |
630d3d5a | 8840 | When the user specifies @option{-ggdb}, GCC normally also uses the |
e5e809f4 | 8841 | value of this macro to select the debugging output format, but with two |
16201823 | 8842 | exceptions. If @code{DWARF2_DEBUGGING_INFO} is defined, GCC uses the |
e5e809f4 | 8843 | value @code{DWARF2_DEBUG}. Otherwise, if @code{DBX_DEBUGGING_INFO} is |
a3a15b4d | 8844 | defined, GCC uses @code{DBX_DEBUG}. |
deabc777 | 8845 | |
feca2ed3 | 8846 | The value of this macro only affects the default debugging output; the |
630d3d5a | 8847 | user can always get a specific type of output by using @option{-gstabs}, |
def66b10 | 8848 | @option{-gcoff}, @option{-gdwarf-2}, @option{-gxcoff}, or @option{-gvms}. |
a2c4f8e0 | 8849 | @end defmac |
feca2ed3 JW |
8850 | |
8851 | @node DBX Options | |
8852 | @subsection Specific Options for DBX Output | |
8853 | ||
8854 | @c prevent bad page break with this line | |
8855 | These are specific options for DBX output. | |
8856 | ||
a2c4f8e0 | 8857 | @defmac DBX_DEBUGGING_INFO |
a3a15b4d | 8858 | Define this macro if GCC should produce debugging output for DBX |
630d3d5a | 8859 | in response to the @option{-g} option. |
a2c4f8e0 | 8860 | @end defmac |
feca2ed3 | 8861 | |
a2c4f8e0 | 8862 | @defmac XCOFF_DEBUGGING_INFO |
a3a15b4d | 8863 | Define this macro if GCC should produce XCOFF format debugging output |
630d3d5a | 8864 | in response to the @option{-g} option. This is a variant of DBX format. |
a2c4f8e0 | 8865 | @end defmac |
feca2ed3 | 8866 | |
a2c4f8e0 | 8867 | @defmac DEFAULT_GDB_EXTENSIONS |
a3a15b4d | 8868 | Define this macro to control whether GCC should by default generate |
feca2ed3 JW |
8869 | GDB's extended version of DBX debugging information (assuming DBX-format |
8870 | debugging information is enabled at all). If you don't define the | |
8871 | macro, the default is 1: always generate the extended information | |
8872 | if there is any occasion to. | |
a2c4f8e0 | 8873 | @end defmac |
feca2ed3 | 8874 | |
a2c4f8e0 | 8875 | @defmac DEBUG_SYMS_TEXT |
feca2ed3 JW |
8876 | Define this macro if all @code{.stabs} commands should be output while |
8877 | in the text section. | |
a2c4f8e0 | 8878 | @end defmac |
feca2ed3 | 8879 | |
a2c4f8e0 | 8880 | @defmac ASM_STABS_OP |
047c1c92 HPN |
8881 | A C string constant, including spacing, naming the assembler pseudo op to |
8882 | use instead of @code{"\t.stabs\t"} to define an ordinary debugging symbol. | |
8883 | If you don't define this macro, @code{"\t.stabs\t"} is used. This macro | |
8884 | applies only to DBX debugging information format. | |
a2c4f8e0 | 8885 | @end defmac |
feca2ed3 | 8886 | |
a2c4f8e0 | 8887 | @defmac ASM_STABD_OP |
047c1c92 HPN |
8888 | A C string constant, including spacing, naming the assembler pseudo op to |
8889 | use instead of @code{"\t.stabd\t"} to define a debugging symbol whose | |
8890 | value is the current location. If you don't define this macro, | |
8891 | @code{"\t.stabd\t"} is used. This macro applies only to DBX debugging | |
8892 | information format. | |
a2c4f8e0 | 8893 | @end defmac |
feca2ed3 | 8894 | |
a2c4f8e0 | 8895 | @defmac ASM_STABN_OP |
047c1c92 HPN |
8896 | A C string constant, including spacing, naming the assembler pseudo op to |
8897 | use instead of @code{"\t.stabn\t"} to define a debugging symbol with no | |
8898 | name. If you don't define this macro, @code{"\t.stabn\t"} is used. This | |
8899 | macro applies only to DBX debugging information format. | |
a2c4f8e0 | 8900 | @end defmac |
feca2ed3 | 8901 | |
a2c4f8e0 | 8902 | @defmac DBX_NO_XREFS |
feca2ed3 JW |
8903 | Define this macro if DBX on your system does not support the construct |
8904 | @samp{xs@var{tagname}}. On some systems, this construct is used to | |
8905 | describe a forward reference to a structure named @var{tagname}. | |
8906 | On other systems, this construct is not supported at all. | |
a2c4f8e0 | 8907 | @end defmac |
feca2ed3 | 8908 | |
a2c4f8e0 | 8909 | @defmac DBX_CONTIN_LENGTH |
feca2ed3 JW |
8910 | A symbol name in DBX-format debugging information is normally |
8911 | continued (split into two separate @code{.stabs} directives) when it | |
8912 | exceeds a certain length (by default, 80 characters). On some | |
8913 | operating systems, DBX requires this splitting; on others, splitting | |
8914 | must not be done. You can inhibit splitting by defining this macro | |
8915 | with the value zero. You can override the default splitting-length by | |
8916 | defining this macro as an expression for the length you desire. | |
a2c4f8e0 | 8917 | @end defmac |
feca2ed3 | 8918 | |
a2c4f8e0 | 8919 | @defmac DBX_CONTIN_CHAR |
feca2ed3 JW |
8920 | Normally continuation is indicated by adding a @samp{\} character to |
8921 | the end of a @code{.stabs} string when a continuation follows. To use | |
8922 | a different character instead, define this macro as a character | |
8923 | constant for the character you want to use. Do not define this macro | |
8924 | if backslash is correct for your system. | |
a2c4f8e0 | 8925 | @end defmac |
feca2ed3 | 8926 | |
a2c4f8e0 | 8927 | @defmac DBX_STATIC_STAB_DATA_SECTION |
feca2ed3 JW |
8928 | Define this macro if it is necessary to go to the data section before |
8929 | outputting the @samp{.stabs} pseudo-op for a non-global static | |
8930 | variable. | |
a2c4f8e0 | 8931 | @end defmac |
feca2ed3 | 8932 | |
a2c4f8e0 | 8933 | @defmac DBX_TYPE_DECL_STABS_CODE |
feca2ed3 JW |
8934 | The value to use in the ``code'' field of the @code{.stabs} directive |
8935 | for a typedef. The default is @code{N_LSYM}. | |
a2c4f8e0 | 8936 | @end defmac |
feca2ed3 | 8937 | |
a2c4f8e0 | 8938 | @defmac DBX_STATIC_CONST_VAR_CODE |
feca2ed3 JW |
8939 | The value to use in the ``code'' field of the @code{.stabs} directive |
8940 | for a static variable located in the text section. DBX format does not | |
8941 | provide any ``right'' way to do this. The default is @code{N_FUN}. | |
a2c4f8e0 | 8942 | @end defmac |
feca2ed3 | 8943 | |
a2c4f8e0 | 8944 | @defmac DBX_REGPARM_STABS_CODE |
feca2ed3 JW |
8945 | The value to use in the ``code'' field of the @code{.stabs} directive |
8946 | for a parameter passed in registers. DBX format does not provide any | |
8947 | ``right'' way to do this. The default is @code{N_RSYM}. | |
a2c4f8e0 | 8948 | @end defmac |
feca2ed3 | 8949 | |
a2c4f8e0 | 8950 | @defmac DBX_REGPARM_STABS_LETTER |
feca2ed3 JW |
8951 | The letter to use in DBX symbol data to identify a symbol as a parameter |
8952 | passed in registers. DBX format does not customarily provide any way to | |
8953 | do this. The default is @code{'P'}. | |
a2c4f8e0 | 8954 | @end defmac |
feca2ed3 | 8955 | |
a2c4f8e0 | 8956 | @defmac DBX_FUNCTION_FIRST |
feca2ed3 JW |
8957 | Define this macro if the DBX information for a function and its |
8958 | arguments should precede the assembler code for the function. Normally, | |
8959 | in DBX format, the debugging information entirely follows the assembler | |
8960 | code. | |
a2c4f8e0 | 8961 | @end defmac |
feca2ed3 | 8962 | |
a2c4f8e0 | 8963 | @defmac DBX_BLOCKS_FUNCTION_RELATIVE |
3e487b21 ZW |
8964 | Define this macro, with value 1, if the value of a symbol describing |
8965 | the scope of a block (@code{N_LBRAC} or @code{N_RBRAC}) should be | |
8966 | relative to the start of the enclosing function. Normally, GCC uses | |
8967 | an absolute address. | |
8968 | @end defmac | |
8969 | ||
8970 | @defmac DBX_LINES_FUNCTION_RELATIVE | |
8971 | Define this macro, with value 1, if the value of a symbol indicating | |
8972 | the current line number (@code{N_SLINE}) should be relative to the | |
8973 | start of the enclosing function. Normally, GCC uses an absolute address. | |
a2c4f8e0 | 8974 | @end defmac |
feca2ed3 | 8975 | |
a2c4f8e0 | 8976 | @defmac DBX_USE_BINCL |
f0523f02 | 8977 | Define this macro if GCC should generate @code{N_BINCL} and |
feca2ed3 | 8978 | @code{N_EINCL} stabs for included header files, as on Sun systems. This |
f0523f02 JM |
8979 | macro also directs GCC to output a type number as a pair of a file |
8980 | number and a type number within the file. Normally, GCC does not | |
feca2ed3 JW |
8981 | generate @code{N_BINCL} or @code{N_EINCL} stabs, and it outputs a single |
8982 | number for a type number. | |
a2c4f8e0 | 8983 | @end defmac |
feca2ed3 JW |
8984 | |
8985 | @node DBX Hooks | |
8986 | @subsection Open-Ended Hooks for DBX Format | |
8987 | ||
8988 | @c prevent bad page break with this line | |
8989 | These are hooks for DBX format. | |
8990 | ||
a2c4f8e0 | 8991 | @defmac DBX_OUTPUT_LBRAC (@var{stream}, @var{name}) |
feca2ed3 JW |
8992 | Define this macro to say how to output to @var{stream} the debugging |
8993 | information for the start of a scope level for variable names. The | |
8994 | argument @var{name} is the name of an assembler symbol (for use with | |
8995 | @code{assemble_name}) whose value is the address where the scope begins. | |
a2c4f8e0 | 8996 | @end defmac |
feca2ed3 | 8997 | |
a2c4f8e0 | 8998 | @defmac DBX_OUTPUT_RBRAC (@var{stream}, @var{name}) |
feca2ed3 | 8999 | Like @code{DBX_OUTPUT_LBRAC}, but for the end of a scope level. |
a2c4f8e0 | 9000 | @end defmac |
feca2ed3 | 9001 | |
a2c4f8e0 | 9002 | @defmac DBX_OUTPUT_NFUN (@var{stream}, @var{lscope_label}, @var{decl}) |
374b0b7d AM |
9003 | Define this macro if the target machine requires special handling to |
9004 | output an @code{N_FUN} entry for the function @var{decl}. | |
a2c4f8e0 | 9005 | @end defmac |
374b0b7d | 9006 | |
3e487b21 ZW |
9007 | @defmac DBX_OUTPUT_SOURCE_LINE (@var{stream}, @var{line}, @var{counter}) |
9008 | A C statement to output DBX debugging information before code for line | |
9009 | number @var{line} of the current source file to the stdio stream | |
8a36672b | 9010 | @var{stream}. @var{counter} is the number of time the macro was |
3e487b21 ZW |
9011 | invoked, including the current invocation; it is intended to generate |
9012 | unique labels in the assembly output. | |
9013 | ||
9014 | This macro should not be defined if the default output is correct, or | |
9015 | if it can be made correct by defining @code{DBX_LINES_FUNCTION_RELATIVE}. | |
9016 | @end defmac | |
9017 | ||
a2c4f8e0 | 9018 | @defmac NO_DBX_FUNCTION_END |
feca2ed3 | 9019 | Some stabs encapsulation formats (in particular ECOFF), cannot handle the |
c771326b | 9020 | @code{.stabs "",N_FUN,,0,0,Lscope-function-1} gdb dbx extension construct. |
feca2ed3 JW |
9021 | On those machines, define this macro to turn this feature off without |
9022 | disturbing the rest of the gdb extensions. | |
a2c4f8e0 | 9023 | @end defmac |
feca2ed3 | 9024 | |
5d865dac EB |
9025 | @defmac NO_DBX_BNSYM_ENSYM |
9026 | Some assemblers cannot handle the @code{.stabd BNSYM/ENSYM,0,0} gdb dbx | |
9027 | extension construct. On those machines, define this macro to turn this | |
9028 | feature off without disturbing the rest of the gdb extensions. | |
9029 | @end defmac | |
9030 | ||
feca2ed3 JW |
9031 | @node File Names and DBX |
9032 | @subsection File Names in DBX Format | |
9033 | ||
9034 | @c prevent bad page break with this line | |
9035 | This describes file names in DBX format. | |
9036 | ||
a2c4f8e0 | 9037 | @defmac DBX_OUTPUT_MAIN_SOURCE_FILENAME (@var{stream}, @var{name}) |
feca2ed3 | 9038 | A C statement to output DBX debugging information to the stdio stream |
93a27b7b | 9039 | @var{stream}, which indicates that file @var{name} is the main source |
feca2ed3 JW |
9040 | file---the file specified as the input file for compilation. |
9041 | This macro is called only once, at the beginning of compilation. | |
9042 | ||
9043 | This macro need not be defined if the standard form of output | |
9044 | for DBX debugging information is appropriate. | |
93a27b7b ZW |
9045 | |
9046 | It may be necessary to refer to a label equal to the beginning of the | |
9047 | text section. You can use @samp{assemble_name (stream, ltext_label_name)} | |
9048 | to do so. If you do this, you must also set the variable | |
9049 | @var{used_ltext_label_name} to @code{true}. | |
a2c4f8e0 | 9050 | @end defmac |
feca2ed3 | 9051 | |
93a27b7b ZW |
9052 | @defmac NO_DBX_MAIN_SOURCE_DIRECTORY |
9053 | Define this macro, with value 1, if GCC should not emit an indication | |
9054 | of the current directory for compilation and current source language at | |
9055 | the beginning of the file. | |
9056 | @end defmac | |
feca2ed3 | 9057 | |
93a27b7b ZW |
9058 | @defmac NO_DBX_GCC_MARKER |
9059 | Define this macro, with value 1, if GCC should not emit an indication | |
9060 | that this object file was compiled by GCC@. The default is to emit | |
9061 | an @code{N_OPT} stab at the beginning of every source file, with | |
9062 | @samp{gcc2_compiled.} for the string and value 0. | |
a2c4f8e0 | 9063 | @end defmac |
feca2ed3 | 9064 | |
a2c4f8e0 | 9065 | @defmac DBX_OUTPUT_MAIN_SOURCE_FILE_END (@var{stream}, @var{name}) |
feca2ed3 | 9066 | A C statement to output DBX debugging information at the end of |
93a27b7b ZW |
9067 | compilation of the main source file @var{name}. Output should be |
9068 | written to the stdio stream @var{stream}. | |
feca2ed3 JW |
9069 | |
9070 | If you don't define this macro, nothing special is output at the end | |
9071 | of compilation, which is correct for most machines. | |
a2c4f8e0 | 9072 | @end defmac |
feca2ed3 | 9073 | |
3e487b21 ZW |
9074 | @defmac DBX_OUTPUT_NULL_N_SO_AT_MAIN_SOURCE_FILE_END |
9075 | Define this macro @emph{instead of} defining | |
9076 | @code{DBX_OUTPUT_MAIN_SOURCE_FILE_END}, if what needs to be output at | |
e4ae5e77 | 9077 | the end of compilation is an @code{N_SO} stab with an empty string, |
3e487b21 ZW |
9078 | whose value is the highest absolute text address in the file. |
9079 | @end defmac | |
9080 | ||
feca2ed3 JW |
9081 | @need 2000 |
9082 | @node SDB and DWARF | |
9083 | @subsection Macros for SDB and DWARF Output | |
9084 | ||
9085 | @c prevent bad page break with this line | |
9086 | Here are macros for SDB and DWARF output. | |
9087 | ||
a2c4f8e0 | 9088 | @defmac SDB_DEBUGGING_INFO |
a3a15b4d | 9089 | Define this macro if GCC should produce COFF-style debugging output |
630d3d5a | 9090 | for SDB in response to the @option{-g} option. |
a2c4f8e0 | 9091 | @end defmac |
feca2ed3 | 9092 | |
a2c4f8e0 | 9093 | @defmac DWARF2_DEBUGGING_INFO |
a3a15b4d | 9094 | Define this macro if GCC should produce dwarf version 2 format |
630d3d5a | 9095 | debugging output in response to the @option{-g} option. |
f3ff3f4a | 9096 | |
a1c496cb EC |
9097 | @deftypefn {Target Hook} int TARGET_DWARF_CALLING_CONVENTION (tree @var{function}) |
9098 | Define this to enable the dwarf attribute @code{DW_AT_calling_convention} to | |
9099 | be emitted for each function. Instead of an integer return the enum | |
9100 | value for the @code{DW_CC_} tag. | |
9101 | @end deftypefn | |
9102 | ||
861bb6c1 JL |
9103 | To support optional call frame debugging information, you must also |
9104 | define @code{INCOMING_RETURN_ADDR_RTX} and either set | |
9105 | @code{RTX_FRAME_RELATED_P} on the prologue insns if you use RTL for the | |
9106 | prologue, or call @code{dwarf2out_def_cfa} and @code{dwarf2out_reg_save} | |
08c148a8 | 9107 | as appropriate from @code{TARGET_ASM_FUNCTION_PROLOGUE} if you don't. |
a2c4f8e0 | 9108 | @end defmac |
861bb6c1 | 9109 | |
a2c4f8e0 | 9110 | @defmac DWARF2_FRAME_INFO |
a3a15b4d | 9111 | Define this macro to a nonzero value if GCC should always output |
9ec36da5 | 9112 | Dwarf 2 frame information. If @code{DWARF2_UNWIND_INFO} |
a3a15b4d | 9113 | (@pxref{Exception Region Output} is nonzero, GCC will output this |
9ec36da5 | 9114 | information not matter how you define @code{DWARF2_FRAME_INFO}. |
a2c4f8e0 | 9115 | @end defmac |
9ec36da5 | 9116 | |
a2c4f8e0 | 9117 | @defmac DWARF2_ASM_LINE_DEBUG_INFO |
b2244e22 JW |
9118 | Define this macro to be a nonzero value if the assembler can generate Dwarf 2 |
9119 | line debug info sections. This will result in much more compact line number | |
9120 | tables, and hence is desirable if it works. | |
a2c4f8e0 | 9121 | @end defmac |
b2244e22 | 9122 | |
a2c4f8e0 | 9123 | @defmac ASM_OUTPUT_DWARF_DELTA (@var{stream}, @var{size}, @var{label1}, @var{label2}) |
7606e68f | 9124 | A C statement to issue assembly directives that create a difference |
192d0f89 | 9125 | @var{lab1} minus @var{lab2}, using an integer of the given @var{size}. |
a2c4f8e0 | 9126 | @end defmac |
7606e68f | 9127 | |
192d0f89 | 9128 | @defmac ASM_OUTPUT_DWARF_OFFSET (@var{stream}, @var{size}, @var{label}, @var{section}) |
7606e68f | 9129 | A C statement to issue assembly directives that create a |
192d0f89 GK |
9130 | section-relative reference to the given @var{label}, using an integer of the |
9131 | given @var{size}. The label is known to be defined in the given @var{section}. | |
a2c4f8e0 | 9132 | @end defmac |
7606e68f | 9133 | |
a2c4f8e0 | 9134 | @defmac ASM_OUTPUT_DWARF_PCREL (@var{stream}, @var{size}, @var{label}) |
7606e68f | 9135 | A C statement to issue assembly directives that create a self-relative |
192d0f89 | 9136 | reference to the given @var{label}, using an integer of the given @var{size}. |
a2c4f8e0 | 9137 | @end defmac |
7606e68f | 9138 | |
fdbe66f2 EB |
9139 | @deftypefn {Target Hook} void TARGET_ASM_OUTPUT_DWARF_DTPREL (FILE *@var{FILE}, int @var{size}, rtx @var{x}) |
9140 | If defined, this target hook is a function which outputs a DTP-relative | |
9141 | reference to the given TLS symbol of the specified size. | |
9142 | @end deftypefn | |
9143 | ||
a2c4f8e0 | 9144 | @defmac PUT_SDB_@dots{} |
feca2ed3 JW |
9145 | Define these macros to override the assembler syntax for the special |
9146 | SDB assembler directives. See @file{sdbout.c} for a list of these | |
9147 | macros and their arguments. If the standard syntax is used, you need | |
9148 | not define them yourself. | |
a2c4f8e0 | 9149 | @end defmac |
feca2ed3 | 9150 | |
a2c4f8e0 | 9151 | @defmac SDB_DELIM |
feca2ed3 JW |
9152 | Some assemblers do not support a semicolon as a delimiter, even between |
9153 | SDB assembler directives. In that case, define this macro to be the | |
9154 | delimiter to use (usually @samp{\n}). It is not necessary to define | |
9155 | a new set of @code{PUT_SDB_@var{op}} macros if this is the only change | |
9156 | required. | |
a2c4f8e0 | 9157 | @end defmac |
feca2ed3 | 9158 | |
a2c4f8e0 | 9159 | @defmac SDB_ALLOW_UNKNOWN_REFERENCES |
feca2ed3 JW |
9160 | Define this macro to allow references to unknown structure, |
9161 | union, or enumeration tags to be emitted. Standard COFF does not | |
9162 | allow handling of unknown references, MIPS ECOFF has support for | |
9163 | it. | |
a2c4f8e0 | 9164 | @end defmac |
feca2ed3 | 9165 | |
a2c4f8e0 | 9166 | @defmac SDB_ALLOW_FORWARD_REFERENCES |
feca2ed3 JW |
9167 | Define this macro to allow references to structure, union, or |
9168 | enumeration tags that have not yet been seen to be handled. Some | |
9169 | assemblers choke if forward tags are used, while some require it. | |
a2c4f8e0 | 9170 | @end defmac |
feca2ed3 | 9171 | |
3e487b21 ZW |
9172 | @defmac SDB_OUTPUT_SOURCE_LINE (@var{stream}, @var{line}) |
9173 | A C statement to output SDB debugging information before code for line | |
9174 | number @var{line} of the current source file to the stdio stream | |
9175 | @var{stream}. The default is to emit an @code{.ln} directive. | |
9176 | @end defmac | |
9177 | ||
5f98259a RK |
9178 | @need 2000 |
9179 | @node VMS Debug | |
9180 | @subsection Macros for VMS Debug Format | |
9181 | ||
9182 | @c prevent bad page break with this line | |
9183 | Here are macros for VMS debug format. | |
9184 | ||
a2c4f8e0 | 9185 | @defmac VMS_DEBUGGING_INFO |
5f98259a RK |
9186 | Define this macro if GCC should produce debugging output for VMS |
9187 | in response to the @option{-g} option. The default behavior for VMS | |
9188 | is to generate minimal debug info for a traceback in the absence of | |
9189 | @option{-g} unless explicitly overridden with @option{-g0}. This | |
9190 | behavior is controlled by @code{OPTIMIZATION_OPTIONS} and | |
9191 | @code{OVERRIDE_OPTIONS}. | |
a2c4f8e0 | 9192 | @end defmac |
5f98259a | 9193 | |
b216cd4a | 9194 | @node Floating Point |
feca2ed3 JW |
9195 | @section Cross Compilation and Floating Point |
9196 | @cindex cross compilation and floating point | |
9197 | @cindex floating point and cross compilation | |
9198 | ||
b216cd4a | 9199 | While all modern machines use twos-complement representation for integers, |
feca2ed3 JW |
9200 | there are a variety of representations for floating point numbers. This |
9201 | means that in a cross-compiler the representation of floating point numbers | |
9202 | in the compiled program may be different from that used in the machine | |
9203 | doing the compilation. | |
9204 | ||
feca2ed3 | 9205 | Because different representation systems may offer different amounts of |
b216cd4a ZW |
9206 | range and precision, all floating point constants must be represented in |
9207 | the target machine's format. Therefore, the cross compiler cannot | |
9208 | safely use the host machine's floating point arithmetic; it must emulate | |
9209 | the target's arithmetic. To ensure consistency, GCC always uses | |
9210 | emulation to work with floating point values, even when the host and | |
9211 | target floating point formats are identical. | |
9212 | ||
9213 | The following macros are provided by @file{real.h} for the compiler to | |
9214 | use. All parts of the compiler which generate or optimize | |
ba31d94e ZW |
9215 | floating-point calculations must use these macros. They may evaluate |
9216 | their operands more than once, so operands must not have side effects. | |
feca2ed3 | 9217 | |
b216cd4a ZW |
9218 | @defmac REAL_VALUE_TYPE |
9219 | The C data type to be used to hold a floating point value in the target | |
9220 | machine's format. Typically this is a @code{struct} containing an | |
9221 | array of @code{HOST_WIDE_INT}, but all code should treat it as an opaque | |
9222 | quantity. | |
9223 | @end defmac | |
9224 | ||
9225 | @deftypefn Macro int REAL_VALUES_EQUAL (REAL_VALUE_TYPE @var{x}, REAL_VALUE_TYPE @var{y}) | |
9226 | Compares for equality the two values, @var{x} and @var{y}. If the target | |
9227 | floating point format supports negative zeroes and/or NaNs, | |
9228 | @samp{REAL_VALUES_EQUAL (-0.0, 0.0)} is true, and | |
9229 | @samp{REAL_VALUES_EQUAL (NaN, NaN)} is false. | |
9230 | @end deftypefn | |
9231 | ||
9232 | @deftypefn Macro int REAL_VALUES_LESS (REAL_VALUE_TYPE @var{x}, REAL_VALUE_TYPE @var{y}) | |
9233 | Tests whether @var{x} is less than @var{y}. | |
9234 | @end deftypefn | |
9235 | ||
b216cd4a ZW |
9236 | @deftypefn Macro HOST_WIDE_INT REAL_VALUE_FIX (REAL_VALUE_TYPE @var{x}) |
9237 | Truncates @var{x} to a signed integer, rounding toward zero. | |
9238 | @end deftypefn | |
9239 | ||
9240 | @deftypefn Macro {unsigned HOST_WIDE_INT} REAL_VALUE_UNSIGNED_FIX (REAL_VALUE_TYPE @var{x}) | |
9241 | Truncates @var{x} to an unsigned integer, rounding toward zero. If | |
9242 | @var{x} is negative, returns zero. | |
9243 | @end deftypefn | |
9244 | ||
b216cd4a ZW |
9245 | @deftypefn Macro REAL_VALUE_TYPE REAL_VALUE_ATOF (const char *@var{string}, enum machine_mode @var{mode}) |
9246 | Converts @var{string} into a floating point number in the target machine's | |
9247 | representation for mode @var{mode}. This routine can handle both | |
9248 | decimal and hexadecimal floating point constants, using the syntax | |
9249 | defined by the C language for both. | |
9250 | @end deftypefn | |
feca2ed3 | 9251 | |
15e5ad76 | 9252 | @deftypefn Macro int REAL_VALUE_NEGATIVE (REAL_VALUE_TYPE @var{x}) |
ce3649d2 | 9253 | Returns 1 if @var{x} is negative (including negative zero), 0 otherwise. |
15e5ad76 ZW |
9254 | @end deftypefn |
9255 | ||
b216cd4a ZW |
9256 | @deftypefn Macro int REAL_VALUE_ISINF (REAL_VALUE_TYPE @var{x}) |
9257 | Determines whether @var{x} represents infinity (positive or negative). | |
9258 | @end deftypefn | |
9259 | ||
9260 | @deftypefn Macro int REAL_VALUE_ISNAN (REAL_VALUE_TYPE @var{x}) | |
9261 | Determines whether @var{x} represents a ``NaN'' (not-a-number). | |
9262 | @end deftypefn | |
9263 | ||
9264 | @deftypefn Macro void REAL_ARITHMETIC (REAL_VALUE_TYPE @var{output}, enum tree_code @var{code}, REAL_VALUE_TYPE @var{x}, REAL_VALUE_TYPE @var{y}) | |
9265 | Calculates an arithmetic operation on the two floating point values | |
9266 | @var{x} and @var{y}, storing the result in @var{output} (which must be a | |
9267 | variable). | |
9268 | ||
9269 | The operation to be performed is specified by @var{code}. Only the | |
9270 | following codes are supported: @code{PLUS_EXPR}, @code{MINUS_EXPR}, | |
9271 | @code{MULT_EXPR}, @code{RDIV_EXPR}, @code{MAX_EXPR}, @code{MIN_EXPR}. | |
9272 | ||
9273 | If @code{REAL_ARITHMETIC} is asked to evaluate division by zero and the | |
9274 | target's floating point format cannot represent infinity, it will call | |
9275 | @code{abort}. Callers should check for this situation first, using | |
9276 | @code{MODE_HAS_INFINITIES}. @xref{Storage Layout}. | |
9277 | @end deftypefn | |
9278 | ||
9279 | @deftypefn Macro REAL_VALUE_TYPE REAL_VALUE_NEGATE (REAL_VALUE_TYPE @var{x}) | |
9280 | Returns the negative of the floating point value @var{x}. | |
9281 | @end deftypefn | |
9282 | ||
15e5ad76 ZW |
9283 | @deftypefn Macro REAL_VALUE_TYPE REAL_VALUE_ABS (REAL_VALUE_TYPE @var{x}) |
9284 | Returns the absolute value of @var{x}. | |
9285 | @end deftypefn | |
9286 | ||
b216cd4a ZW |
9287 | @deftypefn Macro REAL_VALUE_TYPE REAL_VALUE_TRUNCATE (REAL_VALUE_TYPE @var{mode}, enum machine_mode @var{x}) |
9288 | Truncates the floating point value @var{x} to fit in @var{mode}. The | |
9289 | return value is still a full-size @code{REAL_VALUE_TYPE}, but it has an | |
ab873839 | 9290 | appropriate bit pattern to be output as a floating constant whose |
b216cd4a ZW |
9291 | precision accords with mode @var{mode}. |
9292 | @end deftypefn | |
9293 | ||
9294 | @deftypefn Macro void REAL_VALUE_TO_INT (HOST_WIDE_INT @var{low}, HOST_WIDE_INT @var{high}, REAL_VALUE_TYPE @var{x}) | |
9295 | Converts a floating point value @var{x} into a double-precision integer | |
9296 | which is then stored into @var{low} and @var{high}. If the value is not | |
9297 | integral, it is truncated. | |
9298 | @end deftypefn | |
9299 | ||
9300 | @deftypefn Macro void REAL_VALUE_FROM_INT (REAL_VALUE_TYPE @var{x}, HOST_WIDE_INT @var{low}, HOST_WIDE_INT @var{high}, enum machine_mode @var{mode}) | |
b216cd4a ZW |
9301 | Converts a double-precision integer found in @var{low} and @var{high}, |
9302 | into a floating point value which is then stored into @var{x}. The | |
9303 | value is truncated to fit in mode @var{mode}. | |
9304 | @end deftypefn | |
feca2ed3 | 9305 | |
9f09b1f2 R |
9306 | @node Mode Switching |
9307 | @section Mode Switching Instructions | |
9308 | @cindex mode switching | |
9309 | The following macros control mode switching optimizations: | |
9310 | ||
a2c4f8e0 | 9311 | @defmac OPTIMIZE_MODE_SWITCHING (@var{entity}) |
9f09b1f2 R |
9312 | Define this macro if the port needs extra instructions inserted for mode |
9313 | switching in an optimizing compilation. | |
9314 | ||
9315 | For an example, the SH4 can perform both single and double precision | |
9316 | floating point operations, but to perform a single precision operation, | |
9317 | the FPSCR PR bit has to be cleared, while for a double precision | |
9318 | operation, this bit has to be set. Changing the PR bit requires a general | |
9319 | purpose register as a scratch register, hence these FPSCR sets have to | |
e979f9e8 | 9320 | be inserted before reload, i.e.@: you can't put this into instruction emitting |
18dbd950 | 9321 | or @code{TARGET_MACHINE_DEPENDENT_REORG}. |
9f09b1f2 R |
9322 | |
9323 | You can have multiple entities that are mode-switched, and select at run time | |
9324 | which entities actually need it. @code{OPTIMIZE_MODE_SWITCHING} should | |
14976c58 | 9325 | return nonzero for any @var{entity} that needs mode-switching. |
9f09b1f2 R |
9326 | If you define this macro, you also have to define |
9327 | @code{NUM_MODES_FOR_MODE_SWITCHING}, @code{MODE_NEEDED}, | |
9328 | @code{MODE_PRIORITY_TO_MODE} and @code{EMIT_MODE_SET}. | |
73774972 EC |
9329 | @code{MODE_AFTER}, @code{MODE_ENTRY}, and @code{MODE_EXIT} |
9330 | are optional. | |
a2c4f8e0 | 9331 | @end defmac |
9f09b1f2 | 9332 | |
a2c4f8e0 | 9333 | @defmac NUM_MODES_FOR_MODE_SWITCHING |
9f09b1f2 R |
9334 | If you define @code{OPTIMIZE_MODE_SWITCHING}, you have to define this as |
9335 | initializer for an array of integers. Each initializer element | |
9336 | N refers to an entity that needs mode switching, and specifies the number | |
9337 | of different modes that might need to be set for this entity. | |
78466c0e JM |
9338 | The position of the initializer in the initializer---starting counting at |
9339 | zero---determines the integer that is used to refer to the mode-switched | |
9f09b1f2 R |
9340 | entity in question. |
9341 | In macros that take mode arguments / yield a mode result, modes are | |
630d3d5a | 9342 | represented as numbers 0 @dots{} N @minus{} 1. N is used to specify that no mode |
9f09b1f2 | 9343 | switch is needed / supplied. |
a2c4f8e0 | 9344 | @end defmac |
9f09b1f2 | 9345 | |
a2c4f8e0 | 9346 | @defmac MODE_NEEDED (@var{entity}, @var{insn}) |
9f09b1f2 R |
9347 | @var{entity} is an integer specifying a mode-switched entity. If |
9348 | @code{OPTIMIZE_MODE_SWITCHING} is defined, you must define this macro to | |
9349 | return an integer value not larger than the corresponding element in | |
aee96fe9 JM |
9350 | @code{NUM_MODES_FOR_MODE_SWITCHING}, to denote the mode that @var{entity} must |
9351 | be switched into prior to the execution of @var{insn}. | |
a2c4f8e0 | 9352 | @end defmac |
9f09b1f2 | 9353 | |
73774972 EC |
9354 | @defmac MODE_AFTER (@var{mode}, @var{insn}) |
9355 | If this macro is defined, it is evaluated for every @var{insn} during | |
8a36672b | 9356 | mode switching. It determines the mode that an insn results in (if |
73774972 EC |
9357 | different from the incoming mode). |
9358 | @end defmac | |
9359 | ||
9360 | @defmac MODE_ENTRY (@var{entity}) | |
9361 | If this macro is defined, it is evaluated for every @var{entity} that needs | |
8a36672b JM |
9362 | mode switching. It should evaluate to an integer, which is a mode that |
9363 | @var{entity} is assumed to be switched to at function entry. If @code{MODE_ENTRY} | |
73774972 EC |
9364 | is defined then @code{MODE_EXIT} must be defined. |
9365 | @end defmac | |
9366 | ||
9367 | @defmac MODE_EXIT (@var{entity}) | |
9f09b1f2 | 9368 | If this macro is defined, it is evaluated for every @var{entity} that needs |
8a36672b JM |
9369 | mode switching. It should evaluate to an integer, which is a mode that |
9370 | @var{entity} is assumed to be switched to at function exit. If @code{MODE_EXIT} | |
73774972 | 9371 | is defined then @code{MODE_ENTRY} must be defined. |
a2c4f8e0 | 9372 | @end defmac |
9f09b1f2 | 9373 | |
a2c4f8e0 | 9374 | @defmac MODE_PRIORITY_TO_MODE (@var{entity}, @var{n}) |
aee96fe9 JM |
9375 | This macro specifies the order in which modes for @var{entity} are processed. |
9376 | 0 is the highest priority, @code{NUM_MODES_FOR_MODE_SWITCHING[@var{entity}] - 1} the | |
9f09b1f2 | 9377 | lowest. The value of the macro should be an integer designating a mode |
aee96fe9 | 9378 | for @var{entity}. For any fixed @var{entity}, @code{mode_priority_to_mode} |
630d3d5a | 9379 | (@var{entity}, @var{n}) shall be a bijection in 0 @dots{} |
aee96fe9 | 9380 | @code{num_modes_for_mode_switching[@var{entity}] - 1}. |
a2c4f8e0 | 9381 | @end defmac |
9f09b1f2 | 9382 | |
a2c4f8e0 | 9383 | @defmac EMIT_MODE_SET (@var{entity}, @var{mode}, @var{hard_regs_live}) |
9f09b1f2 R |
9384 | Generate one or more insns to set @var{entity} to @var{mode}. |
9385 | @var{hard_reg_live} is the set of hard registers live at the point where | |
9386 | the insn(s) are to be inserted. | |
a2c4f8e0 | 9387 | @end defmac |
9f09b1f2 | 9388 | |
91d231cb JM |
9389 | @node Target Attributes |
9390 | @section Defining target-specific uses of @code{__attribute__} | |
9391 | @cindex target attributes | |
9392 | @cindex machine attributes | |
9393 | @cindex attributes, target-specific | |
9394 | ||
9395 | Target-specific attributes may be defined for functions, data and types. | |
9396 | These are described using the following target hooks; they also need to | |
9397 | be documented in @file{extend.texi}. | |
9398 | ||
9399 | @deftypevr {Target Hook} {const struct attribute_spec *} TARGET_ATTRIBUTE_TABLE | |
9400 | If defined, this target hook points to an array of @samp{struct | |
9401 | attribute_spec} (defined in @file{tree.h}) specifying the machine | |
9402 | specific attributes for this target and some of the restrictions on the | |
9403 | entities to which these attributes are applied and the arguments they | |
9404 | take. | |
9405 | @end deftypevr | |
9406 | ||
9407 | @deftypefn {Target Hook} int TARGET_COMP_TYPE_ATTRIBUTES (tree @var{type1}, tree @var{type2}) | |
9408 | If defined, this target hook is a function which returns zero if the attributes on | |
9409 | @var{type1} and @var{type2} are incompatible, one if they are compatible, | |
9410 | and two if they are nearly compatible (which causes a warning to be | |
9411 | generated). If this is not defined, machine-specific attributes are | |
9412 | supposed always to be compatible. | |
9413 | @end deftypefn | |
9414 | ||
9415 | @deftypefn {Target Hook} void TARGET_SET_DEFAULT_TYPE_ATTRIBUTES (tree @var{type}) | |
9416 | If defined, this target hook is a function which assigns default attributes to | |
9417 | newly defined @var{type}. | |
9418 | @end deftypefn | |
9419 | ||
9420 | @deftypefn {Target Hook} tree TARGET_MERGE_TYPE_ATTRIBUTES (tree @var{type1}, tree @var{type2}) | |
9421 | Define this target hook if the merging of type attributes needs special | |
9422 | handling. If defined, the result is a list of the combined | |
9423 | @code{TYPE_ATTRIBUTES} of @var{type1} and @var{type2}. It is assumed | |
9424 | that @code{comptypes} has already been called and returned 1. This | |
9425 | function may call @code{merge_attributes} to handle machine-independent | |
9426 | merging. | |
9427 | @end deftypefn | |
9428 | ||
9429 | @deftypefn {Target Hook} tree TARGET_MERGE_DECL_ATTRIBUTES (tree @var{olddecl}, tree @var{newdecl}) | |
9430 | Define this target hook if the merging of decl attributes needs special | |
9431 | handling. If defined, the result is a list of the combined | |
9432 | @code{DECL_ATTRIBUTES} of @var{olddecl} and @var{newdecl}. | |
9433 | @var{newdecl} is a duplicate declaration of @var{olddecl}. Examples of | |
9434 | when this is needed are when one attribute overrides another, or when an | |
9435 | attribute is nullified by a subsequent definition. This function may | |
9436 | call @code{merge_attributes} to handle machine-independent merging. | |
9437 | ||
9438 | @findex TARGET_DLLIMPORT_DECL_ATTRIBUTES | |
b2ca3702 MM |
9439 | If the only target-specific handling you require is @samp{dllimport} |
9440 | for Microsoft Windows targets, you should define the macro | |
9441 | @code{TARGET_DLLIMPORT_DECL_ATTRIBUTES} to @code{1}. The compiler | |
9442 | will then define a function called | |
9443 | @code{merge_dllimport_decl_attributes} which can then be defined as | |
9444 | the expansion of @code{TARGET_MERGE_DECL_ATTRIBUTES}. You can also | |
9445 | add @code{handle_dll_attribute} in the attribute table for your port | |
9446 | to perform initial processing of the @samp{dllimport} and | |
9447 | @samp{dllexport} attributes. This is done in @file{i386/cygwin.h} and | |
9448 | @file{i386/i386.c}, for example. | |
91d231cb JM |
9449 | @end deftypefn |
9450 | ||
43d9ad1d DS |
9451 | @deftypefn {Target Hook} bool TARGET_VALID_DLLIMPORT_ATTRIBUTE_P (tree @var{decl}) |
9452 | @var{decl} is a variable or function with @code{__attribute__((dllimport))} | |
9453 | specified. Use this hook if the target needs to add extra validation | |
9454 | checks to @code{handle_dll_attribute}. | |
9455 | @end deftypefn | |
9456 | ||
63c5b495 | 9457 | @defmac TARGET_DECLSPEC |
1a141fe1 | 9458 | Define this macro to a nonzero value if you want to treat |
63c5b495 MM |
9459 | @code{__declspec(X)} as equivalent to @code{__attribute((X))}. By |
9460 | default, this behavior is enabled only for targets that define | |
9461 | @code{TARGET_DLLIMPORT_DECL_ATTRIBUTES}. The current implementation | |
9462 | of @code{__declspec} is via a built-in macro, but you should not rely | |
9463 | on this implementation detail. | |
9464 | @end defmac | |
9465 | ||
91d231cb JM |
9466 | @deftypefn {Target Hook} void TARGET_INSERT_ATTRIBUTES (tree @var{node}, tree *@var{attr_ptr}) |
9467 | Define this target hook if you want to be able to add attributes to a decl | |
9468 | when it is being created. This is normally useful for back ends which | |
9469 | wish to implement a pragma by using the attributes which correspond to | |
9470 | the pragma's effect. The @var{node} argument is the decl which is being | |
9471 | created. The @var{attr_ptr} argument is a pointer to the attribute list | |
9472 | for this decl. The list itself should not be modified, since it may be | |
9473 | shared with other decls, but attributes may be chained on the head of | |
9474 | the list and @code{*@var{attr_ptr}} modified to point to the new | |
9475 | attributes, or a copy of the list may be made if further changes are | |
9476 | needed. | |
9477 | @end deftypefn | |
9478 | ||
9479 | @deftypefn {Target Hook} bool TARGET_FUNCTION_ATTRIBUTE_INLINABLE_P (tree @var{fndecl}) | |
9480 | @cindex inlining | |
9481 | This target hook returns @code{true} if it is ok to inline @var{fndecl} | |
9482 | into the current function, despite its having target-specific | |
9483 | attributes, @code{false} otherwise. By default, if a function has a | |
9484 | target specific attribute attached to it, it will not be inlined. | |
9485 | @end deftypefn | |
9486 | ||
ab442df7 MM |
9487 | @deftypefn {Target Hook} bool TARGET_VALID_OPTION_ATTRIBUTE_P (tree @var{fndecl}, tree @var{name}, tree @var{args}, int @var{flags}) |
9488 | This hook is called to parse the @code{attribute(option("..."))}, and | |
9489 | it allows the function to set different target machine compile time | |
9490 | options for the current function that might be different than the | |
9491 | options specified on the command line. The hook should return | |
9492 | @code{true} if the options are valid. | |
9493 | ||
9494 | The hook should set the @var{DECL_FUNCTION_SPECIFIC_TARGET} field in | |
9495 | the function declaration to hold a pointer to a target specific | |
9496 | @var{struct cl_target_option} structure. | |
9497 | @end deftypefn | |
9498 | ||
9499 | @deftypefn {Target Hook} void TARGET_OPTION_SAVE (struct cl_target_option *@var{ptr}) | |
9500 | This hook is called to save any additional target specific information | |
9501 | in the @var{struct cl_target_option} structure for function specific | |
9502 | options. | |
9503 | @xref{Option file format}. | |
9504 | @end deftypefn | |
9505 | ||
9506 | @deftypefn {Target Hook} void TARGET_OPTION_RESTORE (struct cl_target_option *@var{ptr}) | |
9507 | This hook is called to restore any additional target specific | |
9508 | information in the @var{struct cl_target_option} structure for | |
9509 | function specific options. | |
9510 | @end deftypefn | |
9511 | ||
9512 | @deftypefn {Target Hook} void TARGET_OPTION_PRINT (struct cl_target_option *@var{ptr}) | |
9513 | This hook is called to print any additional target specific | |
9514 | information in the @var{struct cl_target_option} structure for | |
9515 | function specific options. | |
9516 | @end deftypefn | |
9517 | ||
9518 | @deftypefn {Target Hook} bool TARGET_OPTION_PRAGMA_PARSE (target @var{args}) | |
9519 | This target hook parses the options for @code{#pragma GCC option} to | |
9520 | set the machine specific options for functions that occur later in the | |
9521 | input stream. The options should be the same as handled by the | |
9522 | @code{TARGET_VALID_OPTION_ATTRIBUTE_P} hook. | |
9523 | @end deftypefn | |
9524 | ||
9525 | @deftypefn {Target Hook} bool TARGET_CAN_INLINE_P (tree @var{caller}, tree @var{callee}) | |
9526 | This target hook returns @code{false} if the @var{caller} function | |
9527 | cannot inline @var{callee}, based on target specific information. By | |
9528 | default, inlining is not allowed if the callee function has function | |
9529 | specific target options and the caller does not use the same options. | |
9530 | @end deftypefn | |
9531 | ||
feb60f03 NS |
9532 | @node Emulated TLS |
9533 | @section Emulating TLS | |
9534 | @cindex Emulated TLS | |
9535 | ||
9536 | For targets whose psABI does not provide Thread Local Storage via | |
9537 | specific relocations and instruction sequences, an emulation layer is | |
9538 | used. A set of target hooks allows this emulation layer to be | |
9539 | configured for the requirements of a particular target. For instance | |
a640c13b | 9540 | the psABI may in fact specify TLS support in terms of an emulation |
feb60f03 NS |
9541 | layer. |
9542 | ||
9543 | The emulation layer works by creating a control object for every TLS | |
9544 | object. To access the TLS object, a lookup function is provided | |
9545 | which, when given the address of the control object, will return the | |
9546 | address of the current thread's instance of the TLS object. | |
9547 | ||
9548 | @deftypevr {Target Hook} {const char *} TARGET_EMUTLS_GET_ADDRESS | |
9549 | Contains the name of the helper function that uses a TLS control | |
9550 | object to locate a TLS instance. The default causes libgcc's | |
9551 | emulated TLS helper function to be used. | |
9552 | @end deftypevr | |
9553 | ||
9554 | @deftypevr {Target Hook} {const char *} TARGET_EMUTLS_REGISTER_COMMON | |
9555 | Contains the name of the helper function that should be used at | |
9556 | program startup to register TLS objects that are implicitly | |
9557 | initialized to zero. If this is @code{NULL}, all TLS objects will | |
9558 | have explicit initializers. The default causes libgcc's emulated TLS | |
9559 | registration function to be used. | |
9560 | @end deftypevr | |
9561 | ||
9562 | @deftypevr {Target Hook} {const char *} TARGET_EMUTLS_VAR_SECTION | |
9563 | Contains the name of the section in which TLS control variables should | |
9564 | be placed. The default of @code{NULL} allows these to be placed in | |
9565 | any section. | |
9566 | @end deftypevr | |
9567 | ||
9568 | @deftypevr {Target Hook} {const char *} TARGET_EMUTLS_TMPL_SECTION | |
9569 | Contains the name of the section in which TLS initializers should be | |
9570 | placed. The default of @code{NULL} allows these to be placed in any | |
9571 | section. | |
9572 | @end deftypevr | |
9573 | ||
9574 | @deftypevr {Target Hook} {const char *} TARGET_EMUTLS_VAR_PREFIX | |
9575 | Contains the prefix to be prepended to TLS control variable names. | |
9576 | The default of @code{NULL} uses a target-specific prefix. | |
9577 | @end deftypevr | |
9578 | ||
9579 | @deftypevr {Target Hook} {const char *} TARGET_EMUTLS_TMPL_PREFIX | |
9580 | Contains the prefix to be prepended to TLS initializer objects. The | |
9581 | default of @code{NULL} uses a target-specific prefix. | |
9582 | @end deftypevr | |
9583 | ||
9584 | @deftypefn {Target Hook} tree TARGET_EMUTLS_VAR_FIELDS (tree @var{type}, tree *@var{name}) | |
9585 | Specifies a function that generates the FIELD_DECLs for a TLS control | |
9586 | object type. @var{type} is the RECORD_TYPE the fields are for and | |
9587 | @var{name} should be filled with the structure tag, if the default of | |
9588 | @code{__emutls_object} is unsuitable. The default creates a type suitable | |
9589 | for libgcc's emulated TLS function. | |
9590 | @end deftypefn | |
9591 | ||
9592 | @deftypefn {Target Hook} tree TARGET_EMUTLS_VAR_INIT (tree @var{var}, tree @var{decl}, tree @var{tmpl_addr}) | |
9593 | Specifies a function that generates the CONSTRUCTOR to initialize a | |
9594 | TLS control object. @var{var} is the TLS control object, @var{decl} | |
9595 | is the TLS object and @var{tmpl_addr} is the address of the | |
9596 | initializer. The default initializes libgcc's emulated TLS control object. | |
9597 | @end deftypefn | |
9598 | ||
9599 | @deftypevr {Target Hook} {bool} TARGET_EMUTLS_VAR_ALIGN_FIXED | |
9600 | Specifies whether the alignment of TLS control variable objects is | |
9601 | fixed and should not be increased as some backends may do to optimize | |
9602 | single objects. The default is false. | |
9603 | @end deftypevr | |
9604 | ||
9605 | @deftypevr {Target Hook} {bool} TARGET_EMUTLS_DEBUG_FORM_TLS_ADDRESS | |
9606 | Specifies whether a DWARF @code{DW_OP_form_tls_address} location descriptor | |
9607 | may be used to describe emulated TLS control objects. | |
9608 | @end deftypevr | |
9609 | ||
d604bca3 MH |
9610 | @node MIPS Coprocessors |
9611 | @section Defining coprocessor specifics for MIPS targets. | |
9612 | @cindex MIPS coprocessor-definition macros | |
9613 | ||
9614 | The MIPS specification allows MIPS implementations to have as many as 4 | |
2dd76960 | 9615 | coprocessors, each with as many as 32 private registers. GCC supports |
d604bca3 MH |
9616 | accessing these registers and transferring values between the registers |
9617 | and memory using asm-ized variables. For example: | |
9618 | ||
9619 | @smallexample | |
9620 | register unsigned int cp0count asm ("c0r1"); | |
9621 | unsigned int d; | |
9622 | ||
9623 | d = cp0count + 3; | |
9624 | @end smallexample | |
9625 | ||
9626 | (``c0r1'' is the default name of register 1 in coprocessor 0; alternate | |
9627 | names may be added as described below, or the default names may be | |
9628 | overridden entirely in @code{SUBTARGET_CONDITIONAL_REGISTER_USAGE}.) | |
9629 | ||
9630 | Coprocessor registers are assumed to be epilogue-used; sets to them will | |
9631 | be preserved even if it does not appear that the register is used again | |
9632 | later in the function. | |
9633 | ||
9634 | Another note: according to the MIPS spec, coprocessor 1 (if present) is | |
8a36672b | 9635 | the FPU@. One accesses COP1 registers through standard mips |
d604bca3 MH |
9636 | floating-point support; they are not included in this mechanism. |
9637 | ||
9638 | There is one macro used in defining the MIPS coprocessor interface which | |
9639 | you may want to override in subtargets; it is described below. | |
9640 | ||
a2c4f8e0 | 9641 | @defmac ALL_COP_ADDITIONAL_REGISTER_NAMES |
d604bca3 MH |
9642 | A comma-separated list (with leading comma) of pairs describing the |
9643 | alternate names of coprocessor registers. The format of each entry should be | |
9644 | @smallexample | |
9645 | @{ @var{alternatename}, @var{register_number}@} | |
9646 | @end smallexample | |
9647 | Default: empty. | |
a2c4f8e0 | 9648 | @end defmac |
d604bca3 | 9649 | |
7bb1ad93 GK |
9650 | @node PCH Target |
9651 | @section Parameters for Precompiled Header Validity Checking | |
9652 | @cindex parameters, precompiled headers | |
9653 | ||
8d932be3 RS |
9654 | @deftypefn {Target Hook} void *TARGET_GET_PCH_VALIDITY (size_t *@var{sz}) |
9655 | This hook returns the data needed by @code{TARGET_PCH_VALID_P} and sets | |
9656 | @samp{*@var{sz}} to the size of the data in bytes. | |
7bb1ad93 GK |
9657 | @end deftypefn |
9658 | ||
8d932be3 RS |
9659 | @deftypefn {Target Hook} const char *TARGET_PCH_VALID_P (const void *@var{data}, size_t @var{sz}) |
9660 | This hook checks whether the options used to create a PCH file are | |
9661 | compatible with the current settings. It returns @code{NULL} | |
9662 | if so and a suitable error message if not. Error messages will | |
9663 | be presented to the user and must be localized using @samp{_(@var{msg})}. | |
9664 | ||
9665 | @var{data} is the data that was returned by @code{TARGET_GET_PCH_VALIDITY} | |
9666 | when the PCH file was created and @var{sz} is the size of that data in bytes. | |
9667 | It's safe to assume that the data was created by the same version of the | |
9668 | compiler, so no format checking is needed. | |
9669 | ||
9670 | The default definition of @code{default_pch_valid_p} should be | |
9671 | suitable for most targets. | |
9672 | @end deftypefn | |
9673 | ||
9674 | @deftypefn {Target Hook} const char *TARGET_CHECK_PCH_TARGET_FLAGS (int @var{pch_flags}) | |
9675 | If this hook is nonnull, the default implementation of | |
9676 | @code{TARGET_PCH_VALID_P} will use it to check for compatible values | |
9677 | of @code{target_flags}. @var{pch_flags} specifies the value that | |
9678 | @code{target_flags} had when the PCH file was created. The return | |
9679 | value is the same as for @code{TARGET_PCH_VALID_P}. | |
7bb1ad93 GK |
9680 | @end deftypefn |
9681 | ||
4185ae53 PB |
9682 | @node C++ ABI |
9683 | @section C++ ABI parameters | |
9684 | @cindex parameters, c++ abi | |
9685 | ||
9686 | @deftypefn {Target Hook} tree TARGET_CXX_GUARD_TYPE (void) | |
9687 | Define this hook to override the integer type used for guard variables. | |
9688 | These are used to implement one-time construction of static objects. The | |
9689 | default is long_long_integer_type_node. | |
9690 | @end deftypefn | |
9691 | ||
9692 | @deftypefn {Target Hook} bool TARGET_CXX_GUARD_MASK_BIT (void) | |
f676971a | 9693 | This hook determines how guard variables are used. It should return |
4185ae53 PB |
9694 | @code{false} (the default) if first byte should be used. A return value of |
9695 | @code{true} indicates the least significant bit should be used. | |
9696 | @end deftypefn | |
9697 | ||
46e995e0 PB |
9698 | @deftypefn {Target Hook} tree TARGET_CXX_GET_COOKIE_SIZE (tree @var{type}) |
9699 | This hook returns the size of the cookie to use when allocating an array | |
9700 | whose elements have the indicated @var{type}. Assumes that it is already | |
9701 | known that a cookie is needed. The default is | |
9702 | @code{max(sizeof (size_t), alignof(type))}, as defined in section 2.7 of the | |
8a36672b | 9703 | IA64/Generic C++ ABI@. |
46e995e0 PB |
9704 | @end deftypefn |
9705 | ||
9706 | @deftypefn {Target Hook} bool TARGET_CXX_COOKIE_HAS_SIZE (void) | |
9707 | This hook should return @code{true} if the element size should be stored in | |
9708 | array cookies. The default is to return @code{false}. | |
9709 | @end deftypefn | |
9710 | ||
d59c7b4b NC |
9711 | @deftypefn {Target Hook} int TARGET_CXX_IMPORT_EXPORT_CLASS (tree @var{type}, int @var{import_export}) |
9712 | If defined by a backend this hook allows the decision made to export | |
9713 | class @var{type} to be overruled. Upon entry @var{import_export} | |
78466c0e | 9714 | will contain 1 if the class is going to be exported, @minus{}1 if it is going |
d59c7b4b NC |
9715 | to be imported and 0 otherwise. This function should return the |
9716 | modified value and perform any other actions necessary to support the | |
9717 | backend's targeted operating system. | |
9718 | @end deftypefn | |
9719 | ||
44d10c10 PB |
9720 | @deftypefn {Target Hook} bool TARGET_CXX_CDTOR_RETURNS_THIS (void) |
9721 | This hook should return @code{true} if constructors and destructors return | |
9722 | the address of the object created/destroyed. The default is to return | |
9723 | @code{false}. | |
9724 | @end deftypefn | |
9725 | ||
af287697 MM |
9726 | @deftypefn {Target Hook} bool TARGET_CXX_KEY_METHOD_MAY_BE_INLINE (void) |
9727 | This hook returns true if the key method for a class (i.e., the method | |
9728 | which, if defined in the current translation unit, causes the virtual | |
9729 | table to be emitted) may be an inline function. Under the standard | |
9730 | Itanium C++ ABI the key method may be an inline function so long as | |
9731 | the function is not declared inline in the class definition. Under | |
9732 | some variants of the ABI, an inline function can never be the key | |
9733 | method. The default is to return @code{true}. | |
9734 | @end deftypefn | |
9735 | ||
1e731102 MM |
9736 | @deftypefn {Target Hook} void TARGET_CXX_DETERMINE_CLASS_DATA_VISIBILITY (tree @var{decl}) |
9737 | @var{decl} is a virtual table, virtual table table, typeinfo object, | |
9738 | or other similar implicit class data object that will be emitted with | |
9739 | external linkage in this translation unit. No ELF visibility has been | |
9740 | explicitly specified. If the target needs to specify a visibility | |
9741 | other than that of the containing class, use this hook to set | |
9742 | @code{DECL_VISIBILITY} and @code{DECL_VISIBILITY_SPECIFIED}. | |
9743 | @end deftypefn | |
9744 | ||
9745 | @deftypefn {Target Hook} bool TARGET_CXX_CLASS_DATA_ALWAYS_COMDAT (void) | |
9746 | This hook returns true (the default) if virtual tables and other | |
9747 | similar implicit class data objects are always COMDAT if they have | |
9748 | external linkage. If this hook returns false, then class data for | |
9749 | classes whose virtual table will be emitted in only one translation | |
9750 | unit will not be COMDAT. | |
505970fc MM |
9751 | @end deftypefn |
9752 | ||
157600d0 GK |
9753 | @deftypefn {Target Hook} bool TARGET_CXX_LIBRARY_RTTI_COMDAT (void) |
9754 | This hook returns true (the default) if the RTTI information for | |
9755 | the basic types which is defined in the C++ runtime should always | |
9756 | be COMDAT, false if it should not be COMDAT. | |
9757 | @end deftypefn | |
9758 | ||
9f62c3e3 PB |
9759 | @deftypefn {Target Hook} bool TARGET_CXX_USE_AEABI_ATEXIT (void) |
9760 | This hook returns true if @code{__aeabi_atexit} (as defined by the ARM EABI) | |
9761 | should be used to register static destructors when @option{-fuse-cxa-atexit} | |
9762 | is in effect. The default is to return false to use @code{__cxa_atexit}. | |
9763 | @end deftypefn | |
9764 | ||
97388150 DS |
9765 | @deftypefn {Target Hook} bool TARGET_CXX_USE_ATEXIT_FOR_CXA_ATEXIT (void) |
9766 | This hook returns true if the target @code{atexit} function can be used | |
9767 | in the same manner as @code{__cxa_atexit} to register C++ static | |
9768 | destructors. This requires that @code{atexit}-registered functions in | |
9769 | shared libraries are run in the correct order when the libraries are | |
9770 | unloaded. The default is to return false. | |
9771 | @end deftypefn | |
9772 | ||
43d9ad1d DS |
9773 | @deftypefn {Target Hook} void TARGET_CXX_ADJUST_CLASS_AT_DEFINITION (tree @var{type}) |
9774 | @var{type} is a C++ class (i.e., RECORD_TYPE or UNION_TYPE) that has just been | |
9775 | defined. Use this hook to make adjustments to the class (eg, tweak | |
9776 | visibility or perform any other required target modifications). | |
9777 | @end deftypefn | |
9778 | ||
feca2ed3 JW |
9779 | @node Misc |
9780 | @section Miscellaneous Parameters | |
9781 | @cindex parameters, miscellaneous | |
9782 | ||
9783 | @c prevent bad page break with this line | |
9784 | Here are several miscellaneous parameters. | |
9785 | ||
e543e219 ZW |
9786 | @defmac HAS_LONG_COND_BRANCH |
9787 | Define this boolean macro to indicate whether or not your architecture | |
9788 | has conditional branches that can span all of memory. It is used in | |
9789 | conjunction with an optimization that partitions hot and cold basic | |
9790 | blocks into separate sections of the executable. If this macro is | |
9791 | set to false, gcc will convert any conditional branches that attempt | |
9792 | to cross between sections into unconditional branches or indirect jumps. | |
9793 | @end defmac | |
9794 | ||
9795 | @defmac HAS_LONG_UNCOND_BRANCH | |
9796 | Define this boolean macro to indicate whether or not your architecture | |
9797 | has unconditional branches that can span all of memory. It is used in | |
9798 | conjunction with an optimization that partitions hot and cold basic | |
9799 | blocks into separate sections of the executable. If this macro is | |
9800 | set to false, gcc will convert any unconditional branches that attempt | |
9801 | to cross between sections into indirect jumps. | |
a2c4f8e0 | 9802 | @end defmac |
8fe0ca0c | 9803 | |
a2c4f8e0 | 9804 | @defmac CASE_VECTOR_MODE |
feca2ed3 JW |
9805 | An alias for a machine mode name. This is the machine mode that |
9806 | elements of a jump-table should have. | |
a2c4f8e0 | 9807 | @end defmac |
feca2ed3 | 9808 | |
a2c4f8e0 | 9809 | @defmac CASE_VECTOR_SHORTEN_MODE (@var{min_offset}, @var{max_offset}, @var{body}) |
33f7f353 JR |
9810 | Optional: return the preferred mode for an @code{addr_diff_vec} |
9811 | when the minimum and maximum offset are known. If you define this, | |
9812 | it enables extra code in branch shortening to deal with @code{addr_diff_vec}. | |
4226378a | 9813 | To make this work, you also have to define @code{INSN_ALIGN} and |
33f7f353 | 9814 | make the alignment for @code{addr_diff_vec} explicit. |
391aaa6b | 9815 | The @var{body} argument is provided so that the offset_unsigned and scale |
33f7f353 | 9816 | flags can be updated. |
a2c4f8e0 | 9817 | @end defmac |
33f7f353 | 9818 | |
a2c4f8e0 | 9819 | @defmac CASE_VECTOR_PC_RELATIVE |
18543a22 | 9820 | Define this macro to be a C expression to indicate when jump-tables |
9c49953c KH |
9821 | should contain relative addresses. You need not define this macro if |
9822 | jump-tables never contain relative addresses, or jump-tables should | |
9823 | contain relative addresses only when @option{-fPIC} or @option{-fPIC} | |
9824 | is in effect. | |
a2c4f8e0 | 9825 | @end defmac |
feca2ed3 | 9826 | |
e6ff3083 AS |
9827 | @deftypefn {Target Hook} unsigned int TARGET_CASE_VALUES_THRESHOLD (void) |
9828 | This function return the smallest number of different values for which it | |
feca2ed3 JW |
9829 | is best to use a jump-table instead of a tree of conditional branches. |
9830 | The default is four for machines with a @code{casesi} instruction and | |
9831 | five otherwise. This is best for most machines. | |
e6ff3083 | 9832 | @end deftypefn |
feca2ed3 | 9833 | |
a2c4f8e0 | 9834 | @defmac CASE_USE_BIT_TESTS |
9bb231fd RS |
9835 | Define this macro to be a C expression to indicate whether C switch |
9836 | statements may be implemented by a sequence of bit tests. This is | |
9837 | advantageous on processors that can efficiently implement left shift | |
9838 | of 1 by the number of bits held in a register, but inappropriate on | |
9839 | targets that would require a loop. By default, this macro returns | |
9840 | @code{true} if the target defines an @code{ashlsi3} pattern, and | |
9841 | @code{false} otherwise. | |
a2c4f8e0 | 9842 | @end defmac |
9bb231fd | 9843 | |
a2c4f8e0 | 9844 | @defmac WORD_REGISTER_OPERATIONS |
feca2ed3 JW |
9845 | Define this macro if operations between registers with integral mode |
9846 | smaller than a word are always performed on the entire register. | |
9847 | Most RISC machines have this property and most CISC machines do not. | |
a2c4f8e0 | 9848 | @end defmac |
feca2ed3 | 9849 | |
7be4d808 | 9850 | @defmac LOAD_EXTEND_OP (@var{mem_mode}) |
feca2ed3 | 9851 | Define this macro to be a C expression indicating when insns that read |
7be4d808 R |
9852 | memory in @var{mem_mode}, an integral mode narrower than a word, set the |
9853 | bits outside of @var{mem_mode} to be either the sign-extension or the | |
feca2ed3 | 9854 | zero-extension of the data read. Return @code{SIGN_EXTEND} for values |
7be4d808 | 9855 | of @var{mem_mode} for which the |
feca2ed3 | 9856 | insn sign-extends, @code{ZERO_EXTEND} for which it zero-extends, and |
f822d252 | 9857 | @code{UNKNOWN} for other modes. |
feca2ed3 | 9858 | |
7be4d808 | 9859 | This macro is not called with @var{mem_mode} non-integral or with a width |
feca2ed3 JW |
9860 | greater than or equal to @code{BITS_PER_WORD}, so you may return any |
9861 | value in this case. Do not define this macro if it would always return | |
f822d252 | 9862 | @code{UNKNOWN}. On machines where this macro is defined, you will normally |
feca2ed3 | 9863 | define it as the constant @code{SIGN_EXTEND} or @code{ZERO_EXTEND}. |
7be4d808 | 9864 | |
f822d252 | 9865 | You may return a non-@code{UNKNOWN} value even if for some hard registers |
7be4d808 R |
9866 | the sign extension is not performed, if for the @code{REGNO_REG_CLASS} |
9867 | of these hard registers @code{CANNOT_CHANGE_MODE_CLASS} returns nonzero | |
9868 | when the @var{from} mode is @var{mem_mode} and the @var{to} mode is any | |
9869 | integral mode larger than this but not larger than @code{word_mode}. | |
9870 | ||
f822d252 | 9871 | You must return @code{UNKNOWN} if for some hard registers that allow this |
7be4d808 R |
9872 | mode, @code{CANNOT_CHANGE_MODE_CLASS} says that they cannot change to |
9873 | @code{word_mode}, but that they can change to another integral mode that | |
9874 | is larger then @var{mem_mode} but still smaller than @code{word_mode}. | |
a2c4f8e0 | 9875 | @end defmac |
feca2ed3 | 9876 | |
a2c4f8e0 | 9877 | @defmac SHORT_IMMEDIATES_SIGN_EXTEND |
77643ab8 MM |
9878 | Define this macro if loading short immediate values into registers sign |
9879 | extends. | |
a2c4f8e0 | 9880 | @end defmac |
77643ab8 | 9881 | |
a2c4f8e0 | 9882 | @defmac FIXUNS_TRUNC_LIKE_FIX_TRUNC |
feca2ed3 JW |
9883 | Define this macro if the same instructions that convert a floating |
9884 | point number to a signed fixed point number also convert validly to an | |
9885 | unsigned one. | |
a2c4f8e0 | 9886 | @end defmac |
feca2ed3 | 9887 | |
bc23502b PB |
9888 | @deftypefn {Target Hook} int TARGET_MIN_DIVISIONS_FOR_RECIP_MUL (enum machine_mode @var{mode}) |
9889 | When @option{-ffast-math} is in effect, GCC tries to optimize | |
9890 | divisions by the same divisor, by turning them into multiplications by | |
9891 | the reciprocal. This target hook specifies the minimum number of divisions | |
9892 | that should be there for GCC to perform the optimization for a variable | |
9893 | of mode @var{mode}. The default implementation returns 3 if the machine | |
9894 | has an instruction for the division, and 2 if it does not. | |
9895 | @end deftypefn | |
9896 | ||
a2c4f8e0 | 9897 | @defmac MOVE_MAX |
feca2ed3 JW |
9898 | The maximum number of bytes that a single instruction can move quickly |
9899 | between memory and registers or between two memory locations. | |
a2c4f8e0 | 9900 | @end defmac |
feca2ed3 | 9901 | |
a2c4f8e0 | 9902 | @defmac MAX_MOVE_MAX |
feca2ed3 JW |
9903 | The maximum number of bytes that a single instruction can move quickly |
9904 | between memory and registers or between two memory locations. If this | |
9905 | is undefined, the default is @code{MOVE_MAX}. Otherwise, it is the | |
9906 | constant value that is the largest value that @code{MOVE_MAX} can have | |
9907 | at run-time. | |
a2c4f8e0 | 9908 | @end defmac |
feca2ed3 | 9909 | |
a2c4f8e0 | 9910 | @defmac SHIFT_COUNT_TRUNCATED |
feca2ed3 JW |
9911 | A C expression that is nonzero if on this machine the number of bits |
9912 | actually used for the count of a shift operation is equal to the number | |
9913 | of bits needed to represent the size of the object being shifted. When | |
df2a54e9 | 9914 | this macro is nonzero, the compiler will assume that it is safe to omit |
feca2ed3 JW |
9915 | a sign-extend, zero-extend, and certain bitwise `and' instructions that |
9916 | truncates the count of a shift operation. On machines that have | |
c771326b | 9917 | instructions that act on bit-fields at variable positions, which may |
feca2ed3 JW |
9918 | include `bit test' instructions, a nonzero @code{SHIFT_COUNT_TRUNCATED} |
9919 | also enables deletion of truncations of the values that serve as | |
c771326b | 9920 | arguments to bit-field instructions. |
feca2ed3 JW |
9921 | |
9922 | If both types of instructions truncate the count (for shifts) and | |
c771326b | 9923 | position (for bit-field operations), or if no variable-position bit-field |
feca2ed3 JW |
9924 | instructions exist, you should define this macro. |
9925 | ||
9926 | However, on some machines, such as the 80386 and the 680x0, truncation | |
9927 | only applies to shift operations and not the (real or pretended) | |
c771326b | 9928 | bit-field operations. Define @code{SHIFT_COUNT_TRUNCATED} to be zero on |
feca2ed3 JW |
9929 | such machines. Instead, add patterns to the @file{md} file that include |
9930 | the implied truncation of the shift instructions. | |
9931 | ||
9932 | You need not define this macro if it would always have the value of zero. | |
a2c4f8e0 | 9933 | @end defmac |
feca2ed3 | 9934 | |
273a2526 RS |
9935 | @anchor{TARGET_SHIFT_TRUNCATION_MASK} |
9936 | @deftypefn {Target Hook} int TARGET_SHIFT_TRUNCATION_MASK (enum machine_mode @var{mode}) | |
9937 | This function describes how the standard shift patterns for @var{mode} | |
9938 | deal with shifts by negative amounts or by more than the width of the mode. | |
9939 | @xref{shift patterns}. | |
9940 | ||
9941 | On many machines, the shift patterns will apply a mask @var{m} to the | |
9942 | shift count, meaning that a fixed-width shift of @var{x} by @var{y} is | |
9943 | equivalent to an arbitrary-width shift of @var{x} by @var{y & m}. If | |
9944 | this is true for mode @var{mode}, the function should return @var{m}, | |
9945 | otherwise it should return 0. A return value of 0 indicates that no | |
9946 | particular behavior is guaranteed. | |
9947 | ||
9948 | Note that, unlike @code{SHIFT_COUNT_TRUNCATED}, this function does | |
9949 | @emph{not} apply to general shift rtxes; it applies only to instructions | |
9950 | that are generated by the named shift patterns. | |
9951 | ||
9952 | The default implementation of this function returns | |
9953 | @code{GET_MODE_BITSIZE (@var{mode}) - 1} if @code{SHIFT_COUNT_TRUNCATED} | |
9954 | and 0 otherwise. This definition is always safe, but if | |
9955 | @code{SHIFT_COUNT_TRUNCATED} is false, and some shift patterns | |
9956 | nevertheless truncate the shift count, you may get better code | |
9957 | by overriding it. | |
9958 | @end deftypefn | |
9959 | ||
a2c4f8e0 | 9960 | @defmac TRULY_NOOP_TRUNCATION (@var{outprec}, @var{inprec}) |
feca2ed3 JW |
9961 | A C expression which is nonzero if on this machine it is safe to |
9962 | ``convert'' an integer of @var{inprec} bits to one of @var{outprec} | |
9963 | bits (where @var{outprec} is smaller than @var{inprec}) by merely | |
9964 | operating on it as if it had only @var{outprec} bits. | |
9965 | ||
9966 | On many machines, this expression can be 1. | |
9967 | ||
9968 | @c rearranged this, removed the phrase "it is reported that". this was | |
9969 | @c to fix an overfull hbox. --mew 10feb93 | |
9970 | When @code{TRULY_NOOP_TRUNCATION} returns 1 for a pair of sizes for | |
9971 | modes for which @code{MODES_TIEABLE_P} is 0, suboptimal code can result. | |
9972 | If this is the case, making @code{TRULY_NOOP_TRUNCATION} return 0 in | |
9973 | such cases may improve things. | |
a2c4f8e0 | 9974 | @end defmac |
feca2ed3 | 9975 | |
b12cbf2c | 9976 | @deftypefn {Target Hook} int TARGET_MODE_REP_EXTENDED (enum machine_mode @var{mode}, enum machine_mode @var{rep_mode}) |
66a4ad37 | 9977 | The representation of an integral mode can be such that the values |
b12cbf2c AN |
9978 | are always extended to a wider integral mode. Return |
9979 | @code{SIGN_EXTEND} if values of @var{mode} are represented in | |
9980 | sign-extended form to @var{rep_mode}. Return @code{UNKNOWN} | |
9981 | otherwise. (Currently, none of the targets use zero-extended | |
9982 | representation this way so unlike @code{LOAD_EXTEND_OP}, | |
9983 | @code{TARGET_MODE_REP_EXTENDED} is expected to return either | |
9984 | @code{SIGN_EXTEND} or @code{UNKNOWN}. Also no target extends | |
9985 | @var{mode} to @var{mode_rep} so that @var{mode_rep} is not the next | |
9986 | widest integral mode and currently we take advantage of this fact.) | |
9987 | ||
9988 | Similarly to @code{LOAD_EXTEND_OP} you may return a non-@code{UNKNOWN} | |
9989 | value even if the extension is not performed on certain hard registers | |
9990 | as long as for the @code{REGNO_REG_CLASS} of these hard registers | |
9991 | @code{CANNOT_CHANGE_MODE_CLASS} returns nonzero. | |
9992 | ||
9993 | Note that @code{TARGET_MODE_REP_EXTENDED} and @code{LOAD_EXTEND_OP} | |
9994 | describe two related properties. If you define | |
9995 | @code{TARGET_MODE_REP_EXTENDED (mode, word_mode)} you probably also want | |
9996 | to define @code{LOAD_EXTEND_OP (mode)} to return the same type of | |
9997 | extension. | |
9998 | ||
9999 | In order to enforce the representation of @code{mode}, | |
10000 | @code{TRULY_NOOP_TRUNCATION} should return false when truncating to | |
10001 | @code{mode}. | |
10002 | @end deftypefn | |
10003 | ||
a2c4f8e0 | 10004 | @defmac STORE_FLAG_VALUE |
feca2ed3 JW |
10005 | A C expression describing the value returned by a comparison operator |
10006 | with an integral mode and stored by a store-flag instruction | |
10007 | (@samp{s@var{cond}}) when the condition is true. This description must | |
10008 | apply to @emph{all} the @samp{s@var{cond}} patterns and all the | |
10009 | comparison operators whose results have a @code{MODE_INT} mode. | |
10010 | ||
630d3d5a JM |
10011 | A value of 1 or @minus{}1 means that the instruction implementing the |
10012 | comparison operator returns exactly 1 or @minus{}1 when the comparison is true | |
feca2ed3 JW |
10013 | and 0 when the comparison is false. Otherwise, the value indicates |
10014 | which bits of the result are guaranteed to be 1 when the comparison is | |
10015 | true. This value is interpreted in the mode of the comparison | |
10016 | operation, which is given by the mode of the first operand in the | |
10017 | @samp{s@var{cond}} pattern. Either the low bit or the sign bit of | |
10018 | @code{STORE_FLAG_VALUE} be on. Presently, only those bits are used by | |
10019 | the compiler. | |
10020 | ||
630d3d5a | 10021 | If @code{STORE_FLAG_VALUE} is neither 1 or @minus{}1, the compiler will |
feca2ed3 JW |
10022 | generate code that depends only on the specified bits. It can also |
10023 | replace comparison operators with equivalent operations if they cause | |
10024 | the required bits to be set, even if the remaining bits are undefined. | |
10025 | For example, on a machine whose comparison operators return an | |
10026 | @code{SImode} value and where @code{STORE_FLAG_VALUE} is defined as | |
10027 | @samp{0x80000000}, saying that just the sign bit is relevant, the | |
10028 | expression | |
10029 | ||
10030 | @smallexample | |
10031 | (ne:SI (and:SI @var{x} (const_int @var{power-of-2})) (const_int 0)) | |
10032 | @end smallexample | |
10033 | ||
10034 | @noindent | |
10035 | can be converted to | |
10036 | ||
10037 | @smallexample | |
10038 | (ashift:SI @var{x} (const_int @var{n})) | |
10039 | @end smallexample | |
10040 | ||
10041 | @noindent | |
10042 | where @var{n} is the appropriate shift count to move the bit being | |
10043 | tested into the sign bit. | |
10044 | ||
10045 | There is no way to describe a machine that always sets the low-order bit | |
10046 | for a true value, but does not guarantee the value of any other bits, | |
10047 | but we do not know of any machine that has such an instruction. If you | |
a3a15b4d | 10048 | are trying to port GCC to such a machine, include an instruction to |
feca2ed3 | 10049 | perform a logical-and of the result with 1 in the pattern for the |
b11cc610 | 10050 | comparison operators and let us know at @email{gcc@@gcc.gnu.org}. |
feca2ed3 JW |
10051 | |
10052 | Often, a machine will have multiple instructions that obtain a value | |
10053 | from a comparison (or the condition codes). Here are rules to guide the | |
10054 | choice of value for @code{STORE_FLAG_VALUE}, and hence the instructions | |
10055 | to be used: | |
10056 | ||
10057 | @itemize @bullet | |
10058 | @item | |
10059 | Use the shortest sequence that yields a valid definition for | |
10060 | @code{STORE_FLAG_VALUE}. It is more efficient for the compiler to | |
10061 | ``normalize'' the value (convert it to, e.g., 1 or 0) than for the | |
10062 | comparison operators to do so because there may be opportunities to | |
10063 | combine the normalization with other operations. | |
10064 | ||
10065 | @item | |
630d3d5a | 10066 | For equal-length sequences, use a value of 1 or @minus{}1, with @minus{}1 being |
feca2ed3 JW |
10067 | slightly preferred on machines with expensive jumps and 1 preferred on |
10068 | other machines. | |
10069 | ||
10070 | @item | |
10071 | As a second choice, choose a value of @samp{0x80000001} if instructions | |
10072 | exist that set both the sign and low-order bits but do not define the | |
10073 | others. | |
10074 | ||
10075 | @item | |
10076 | Otherwise, use a value of @samp{0x80000000}. | |
10077 | @end itemize | |
10078 | ||
10079 | Many machines can produce both the value chosen for | |
10080 | @code{STORE_FLAG_VALUE} and its negation in the same number of | |
10081 | instructions. On those machines, you should also define a pattern for | |
10082 | those cases, e.g., one matching | |
10083 | ||
10084 | @smallexample | |
10085 | (set @var{A} (neg:@var{m} (ne:@var{m} @var{B} @var{C}))) | |
10086 | @end smallexample | |
10087 | ||
10088 | Some machines can also perform @code{and} or @code{plus} operations on | |
10089 | condition code values with less instructions than the corresponding | |
10090 | @samp{s@var{cond}} insn followed by @code{and} or @code{plus}. On those | |
10091 | machines, define the appropriate patterns. Use the names @code{incscc} | |
10092 | and @code{decscc}, respectively, for the patterns which perform | |
10093 | @code{plus} or @code{minus} operations on condition code values. See | |
10094 | @file{rs6000.md} for some examples. The GNU Superoptizer can be used to | |
10095 | find such instruction sequences on other machines. | |
10096 | ||
06f31100 RS |
10097 | If this macro is not defined, the default value, 1, is used. You need |
10098 | not define @code{STORE_FLAG_VALUE} if the machine has no store-flag | |
10099 | instructions, or if the value generated by these instructions is 1. | |
a2c4f8e0 | 10100 | @end defmac |
feca2ed3 | 10101 | |
a2c4f8e0 | 10102 | @defmac FLOAT_STORE_FLAG_VALUE (@var{mode}) |
df2a54e9 | 10103 | A C expression that gives a nonzero @code{REAL_VALUE_TYPE} value that is |
feca2ed3 | 10104 | returned when comparison operators with floating-point results are true. |
fc7ca5fd | 10105 | Define this macro on machines that have comparison operations that return |
feca2ed3 JW |
10106 | floating-point values. If there are no such operations, do not define |
10107 | this macro. | |
a2c4f8e0 | 10108 | @end defmac |
feca2ed3 | 10109 | |
fc7ca5fd | 10110 | @defmac VECTOR_STORE_FLAG_VALUE (@var{mode}) |
a4d05547 | 10111 | A C expression that gives a rtx representing the nonzero true element |
fc7ca5fd RS |
10112 | for vector comparisons. The returned rtx should be valid for the inner |
10113 | mode of @var{mode} which is guaranteed to be a vector mode. Define | |
10114 | this macro on machines that have vector comparison operations that | |
10115 | return a vector result. If there are no such operations, do not define | |
10116 | this macro. Typically, this macro is defined as @code{const1_rtx} or | |
10117 | @code{constm1_rtx}. This macro may return @code{NULL_RTX} to prevent | |
10118 | the compiler optimizing such vector comparison operations for the | |
10119 | given mode. | |
10120 | @end defmac | |
10121 | ||
a2c4f8e0 ZW |
10122 | @defmac CLZ_DEFINED_VALUE_AT_ZERO (@var{mode}, @var{value}) |
10123 | @defmacx CTZ_DEFINED_VALUE_AT_ZERO (@var{mode}, @var{value}) | |
14670a74 SL |
10124 | A C expression that indicates whether the architecture defines a value |
10125 | for @code{clz} or @code{ctz} with a zero operand. | |
10126 | A result of @code{0} indicates the value is undefined. | |
10127 | If the value is defined for only the RTL expression, the macro should | |
10128 | evaluate to @code{1}; if the value applies also to the corresponding optab | |
10129 | entry (which is normally the case if it expands directly into | |
10130 | the corresponding RTL), then the macro should evaluate to @code{2}. | |
10131 | In the cases where the value is defined, @var{value} should be set to | |
10132 | this value. | |
10133 | ||
10134 | If this macro is not defined, the value of @code{clz} or | |
10135 | @code{ctz} at zero is assumed to be undefined. | |
7dba8395 RH |
10136 | |
10137 | This macro must be defined if the target's expansion for @code{ffs} | |
10138 | relies on a particular value to get correct results. Otherwise it | |
14670a74 SL |
10139 | is not necessary, though it may be used to optimize some corner cases, and |
10140 | to provide a default expansion for the @code{ffs} optab. | |
7dba8395 RH |
10141 | |
10142 | Note that regardless of this macro the ``definedness'' of @code{clz} | |
10143 | and @code{ctz} at zero do @emph{not} extend to the builtin functions | |
10144 | visible to the user. Thus one may be free to adjust the value at will | |
10145 | to match the target expansion of these operations without fear of | |
8a36672b | 10146 | breaking the API@. |
a2c4f8e0 | 10147 | @end defmac |
7dba8395 | 10148 | |
a2c4f8e0 | 10149 | @defmac Pmode |
feca2ed3 JW |
10150 | An alias for the machine mode for pointers. On most machines, define |
10151 | this to be the integer mode corresponding to the width of a hardware | |
10152 | pointer; @code{SImode} on 32-bit machine or @code{DImode} on 64-bit machines. | |
10153 | On some machines you must define this to be one of the partial integer | |
10154 | modes, such as @code{PSImode}. | |
10155 | ||
10156 | The width of @code{Pmode} must be at least as large as the value of | |
10157 | @code{POINTER_SIZE}. If it is not equal, you must define the macro | |
10158 | @code{POINTERS_EXTEND_UNSIGNED} to specify how pointers are extended | |
10159 | to @code{Pmode}. | |
a2c4f8e0 | 10160 | @end defmac |
feca2ed3 | 10161 | |
a2c4f8e0 | 10162 | @defmac FUNCTION_MODE |
feca2ed3 | 10163 | An alias for the machine mode used for memory references to functions |
f71e957e DK |
10164 | being called, in @code{call} RTL expressions. On most CISC machines, |
10165 | where an instruction can begin at any byte address, this should be | |
10166 | @code{QImode}. On most RISC machines, where all instructions have fixed | |
10167 | size and alignment, this should be a mode with the same size and alignment | |
10168 | as the machine instruction words - typically @code{SImode} or @code{HImode}. | |
a2c4f8e0 | 10169 | @end defmac |
feca2ed3 | 10170 | |
a2c4f8e0 | 10171 | @defmac STDC_0_IN_SYSTEM_HEADERS |
ee773fcc NB |
10172 | In normal operation, the preprocessor expands @code{__STDC__} to the |
10173 | constant 1, to signify that GCC conforms to ISO Standard C@. On some | |
10174 | hosts, like Solaris, the system compiler uses a different convention, | |
10175 | where @code{__STDC__} is normally 0, but is 1 if the user specifies | |
10176 | strict conformance to the C Standard. | |
10177 | ||
10178 | Defining @code{STDC_0_IN_SYSTEM_HEADERS} makes GNU CPP follows the host | |
10179 | convention when processing system header files, but when processing user | |
10180 | files @code{__STDC__} will always expand to 1. | |
a2c4f8e0 | 10181 | @end defmac |
ee773fcc | 10182 | |
a2c4f8e0 | 10183 | @defmac NO_IMPLICIT_EXTERN_C |
161d7b59 | 10184 | Define this macro if the system header files support C++ as well as C@. |
feca2ed3 JW |
10185 | This macro inhibits the usual method of using system header files in |
10186 | C++, which is to pretend that the file's contents are enclosed in | |
10187 | @samp{extern "C" @{@dots{}@}}. | |
a2c4f8e0 | 10188 | @end defmac |
feca2ed3 | 10189 | |
feca2ed3 JW |
10190 | @findex #pragma |
10191 | @findex pragma | |
a2c4f8e0 | 10192 | @defmac REGISTER_TARGET_PRAGMAS () |
8b97c5f8 | 10193 | Define this macro if you want to implement any target-specific pragmas. |
a5da89c6 | 10194 | If defined, it is a C expression which makes a series of calls to |
b5b3e36a DJ |
10195 | @code{c_register_pragma} or @code{c_register_pragma_with_expansion} |
10196 | for each pragma. The macro may also do any | |
a5da89c6 | 10197 | setup required for the pragmas. |
8b97c5f8 ZW |
10198 | |
10199 | The primary reason to define this macro is to provide compatibility with | |
10200 | other compilers for the same target. In general, we discourage | |
161d7b59 | 10201 | definition of target-specific pragmas for GCC@. |
feca2ed3 | 10202 | |
c237e94a | 10203 | If the pragma can be implemented by attributes then you should consider |
91d231cb | 10204 | defining the target hook @samp{TARGET_INSERT_ATTRIBUTES} as well. |
f09db6e0 | 10205 | |
8b97c5f8 ZW |
10206 | Preprocessor macros that appear on pragma lines are not expanded. All |
10207 | @samp{#pragma} directives that do not match any registered pragma are | |
630d3d5a | 10208 | silently ignored, unless the user specifies @option{-Wunknown-pragmas}. |
a2c4f8e0 | 10209 | @end defmac |
8b97c5f8 | 10210 | |
c58b209a | 10211 | @deftypefun void c_register_pragma (const char *@var{space}, const char *@var{name}, void (*@var{callback}) (struct cpp_reader *)) |
b5b3e36a | 10212 | @deftypefunx void c_register_pragma_with_expansion (const char *@var{space}, const char *@var{name}, void (*@var{callback}) (struct cpp_reader *)) |
8b97c5f8 | 10213 | |
b5b3e36a DJ |
10214 | Each call to @code{c_register_pragma} or |
10215 | @code{c_register_pragma_with_expansion} establishes one pragma. The | |
8b97c5f8 ZW |
10216 | @var{callback} routine will be called when the preprocessor encounters a |
10217 | pragma of the form | |
10218 | ||
10219 | @smallexample | |
10220 | #pragma [@var{space}] @var{name} @dots{} | |
10221 | @end smallexample | |
10222 | ||
a5da89c6 NB |
10223 | @var{space} is the case-sensitive namespace of the pragma, or |
10224 | @code{NULL} to put the pragma in the global namespace. The callback | |
10225 | routine receives @var{pfile} as its first argument, which can be passed | |
51fabca5 | 10226 | on to cpplib's functions if necessary. You can lex tokens after the |
75ce3d48 | 10227 | @var{name} by calling @code{pragma_lex}. Tokens that are not read by the |
51fabca5 | 10228 | callback will be silently ignored. The end of the line is indicated by |
b5b3e36a DJ |
10229 | a token of type @code{CPP_EOF}. Macro expansion occurs on the |
10230 | arguments of pragmas registered with | |
10231 | @code{c_register_pragma_with_expansion} but not on the arguments of | |
10232 | pragmas registered with @code{c_register_pragma}. | |
8b97c5f8 | 10233 | |
75ce3d48 | 10234 | Note that the use of @code{pragma_lex} is specific to the C and C++ |
aac69a49 | 10235 | compilers. It will not work in the Java or Fortran compilers, or any |
75ce3d48 | 10236 | other language compilers for that matter. Thus if @code{pragma_lex} is going |
aac69a49 | 10237 | to be called from target-specific code, it must only be done so when |
c771326b | 10238 | building the C and C++ compilers. This can be done by defining the |
aac69a49 | 10239 | variables @code{c_target_objs} and @code{cxx_target_objs} in the |
aee96fe9 | 10240 | target entry in the @file{config.gcc} file. These variables should name |
aac69a49 | 10241 | the target-specific, language-specific object file which contains the |
75ce3d48 | 10242 | code that uses @code{pragma_lex}. Note it will also be necessary to add a |
aac69a49 NC |
10243 | rule to the makefile fragment pointed to by @code{tmake_file} that shows |
10244 | how to build this object file. | |
8b97c5f8 ZW |
10245 | @end deftypefun |
10246 | ||
e2af664c NC |
10247 | @findex #pragma |
10248 | @findex pragma | |
a2c4f8e0 | 10249 | @defmac HANDLE_SYSV_PRAGMA |
e2af664c NC |
10250 | Define this macro (to a value of 1) if you want the System V style |
10251 | pragmas @samp{#pragma pack(<n>)} and @samp{#pragma weak <name> | |
10252 | [=<value>]} to be supported by gcc. | |
10253 | ||
10254 | The pack pragma specifies the maximum alignment (in bytes) of fields | |
10255 | within a structure, in much the same way as the @samp{__aligned__} and | |
10256 | @samp{__packed__} @code{__attribute__}s do. A pack value of zero resets | |
c21cd8b1 | 10257 | the behavior to the default. |
e2af664c | 10258 | |
e4850f36 | 10259 | A subtlety for Microsoft Visual C/C++ style bit-field packing |
431ae0bf | 10260 | (e.g.@: -mms-bitfields) for targets that support it: |
e4850f36 DR |
10261 | When a bit-field is inserted into a packed record, the whole size |
10262 | of the underlying type is used by one or more same-size adjacent | |
10263 | bit-fields (that is, if its long:3, 32 bits is used in the record, | |
10264 | and any additional adjacent long bit-fields are packed into the same | |
8a36672b | 10265 | chunk of 32 bits. However, if the size changes, a new field of that |
e4850f36 DR |
10266 | size is allocated). |
10267 | ||
10268 | If both MS bit-fields and @samp{__attribute__((packed))} are used, | |
8a36672b | 10269 | the latter will take precedence. If @samp{__attribute__((packed))} is |
e4850f36 DR |
10270 | used on a single field when MS bit-fields are in use, it will take |
10271 | precedence for that field, but the alignment of the rest of the structure | |
10272 | may affect its placement. | |
10273 | ||
e2af664c NC |
10274 | The weak pragma only works if @code{SUPPORTS_WEAK} and |
10275 | @code{ASM_WEAKEN_LABEL} are defined. If enabled it allows the creation | |
10276 | of specifically named weak labels, optionally with a value. | |
a2c4f8e0 | 10277 | @end defmac |
e2af664c | 10278 | |
e2af664c NC |
10279 | @findex #pragma |
10280 | @findex pragma | |
a2c4f8e0 | 10281 | @defmac HANDLE_PRAGMA_PACK_PUSH_POP |
e2af664c | 10282 | Define this macro (to a value of 1) if you want to support the Win32 |
467cecf3 JB |
10283 | style pragmas @samp{#pragma pack(push[,@var{n}])} and @samp{#pragma |
10284 | pack(pop)}. The @samp{pack(push,[@var{n}])} pragma specifies the maximum | |
10285 | alignment (in bytes) of fields within a structure, in much the same way as | |
10286 | the @samp{__aligned__} and @samp{__packed__} @code{__attribute__}s do. A | |
c21cd8b1 | 10287 | pack value of zero resets the behavior to the default. Successive |
e2af664c NC |
10288 | invocations of this pragma cause the previous values to be stacked, so |
10289 | that invocations of @samp{#pragma pack(pop)} will return to the previous | |
10290 | value. | |
a2c4f8e0 | 10291 | @end defmac |
feca2ed3 | 10292 | |
b5b3e36a DJ |
10293 | @defmac HANDLE_PRAGMA_PACK_WITH_EXPANSION |
10294 | Define this macro, as well as | |
10295 | @code{HANDLE_SYSV_PRAGMA}, if macros should be expanded in the | |
10296 | arguments of @samp{#pragma pack}. | |
10297 | @end defmac | |
10298 | ||
467cecf3 JB |
10299 | @defmac TARGET_DEFAULT_PACK_STRUCT |
10300 | If your target requires a structure packing default other than 0 (meaning | |
0bdcd332 | 10301 | the machine default), define this macro to the necessary value (in bytes). |
8b7d4300 | 10302 | This must be a value that would also be valid to use with |
467cecf3 JB |
10303 | @samp{#pragma pack()} (that is, a small power of two). |
10304 | @end defmac | |
10305 | ||
121de39f RH |
10306 | @findex #pragma |
10307 | @findex pragma | |
10308 | @defmac HANDLE_PRAGMA_PUSH_POP_MACRO | |
10309 | Define this macro if you want to support the Win32 style pragmas | |
10310 | @samp{#pragma push_macro(macro-name-as-string)} and @samp{#pragma | |
10311 | pop_macro(macro-name-as-string)}. The @samp{#pragma push_macro( | |
10312 | macro-name-as-string)} pragma saves the named macro and via | |
10313 | @samp{#pragma pop_macro(macro-name-as-string)} it will return to the | |
10314 | previous value. | |
10315 | @end defmac | |
10316 | ||
10317 | ||
a2c4f8e0 | 10318 | @defmac DOLLARS_IN_IDENTIFIERS |
b1822ccc | 10319 | Define this macro to control use of the character @samp{$} in |
170ea7b9 | 10320 | identifier names for the C family of languages. 0 means @samp{$} is |
b1822ccc NB |
10321 | not allowed by default; 1 means it is allowed. 1 is the default; |
10322 | there is no need to define this macro in that case. | |
a2c4f8e0 | 10323 | @end defmac |
feca2ed3 | 10324 | |
a2c4f8e0 | 10325 | @defmac NO_DOLLAR_IN_LABEL |
feca2ed3 JW |
10326 | Define this macro if the assembler does not accept the character |
10327 | @samp{$} in label names. By default constructors and destructors in | |
10328 | G++ have @samp{$} in the identifiers. If this macro is defined, | |
10329 | @samp{.} is used instead. | |
a2c4f8e0 | 10330 | @end defmac |
feca2ed3 | 10331 | |
a2c4f8e0 | 10332 | @defmac NO_DOT_IN_LABEL |
feca2ed3 JW |
10333 | Define this macro if the assembler does not accept the character |
10334 | @samp{.} in label names. By default constructors and destructors in G++ | |
10335 | have names that use @samp{.}. If this macro is defined, these names | |
10336 | are rewritten to avoid @samp{.}. | |
a2c4f8e0 | 10337 | @end defmac |
feca2ed3 | 10338 | |
a2c4f8e0 | 10339 | @defmac INSN_SETS_ARE_DELAYED (@var{insn}) |
feca2ed3 JW |
10340 | Define this macro as a C expression that is nonzero if it is safe for the |
10341 | delay slot scheduler to place instructions in the delay slot of @var{insn}, | |
10342 | even if they appear to use a resource set or clobbered in @var{insn}. | |
a3a15b4d | 10343 | @var{insn} is always a @code{jump_insn} or an @code{insn}; GCC knows that |
feca2ed3 JW |
10344 | every @code{call_insn} has this behavior. On machines where some @code{insn} |
10345 | or @code{jump_insn} is really a function call and hence has this behavior, | |
10346 | you should define this macro. | |
10347 | ||
10348 | You need not define this macro if it would always return zero. | |
a2c4f8e0 | 10349 | @end defmac |
feca2ed3 | 10350 | |
a2c4f8e0 | 10351 | @defmac INSN_REFERENCES_ARE_DELAYED (@var{insn}) |
feca2ed3 JW |
10352 | Define this macro as a C expression that is nonzero if it is safe for the |
10353 | delay slot scheduler to place instructions in the delay slot of @var{insn}, | |
10354 | even if they appear to set or clobber a resource referenced in @var{insn}. | |
10355 | @var{insn} is always a @code{jump_insn} or an @code{insn}. On machines where | |
10356 | some @code{insn} or @code{jump_insn} is really a function call and its operands | |
10357 | are registers whose use is actually in the subroutine it calls, you should | |
10358 | define this macro. Doing so allows the delay slot scheduler to move | |
10359 | instructions which copy arguments into the argument registers into the delay | |
10360 | slot of @var{insn}. | |
10361 | ||
10362 | You need not define this macro if it would always return zero. | |
a2c4f8e0 | 10363 | @end defmac |
feca2ed3 | 10364 | |
a2c4f8e0 | 10365 | @defmac MULTIPLE_SYMBOL_SPACES |
15072eb1 ZW |
10366 | Define this macro as a C expression that is nonzero if, in some cases, |
10367 | global symbols from one translation unit may not be bound to undefined | |
10368 | symbols in another translation unit without user intervention. For | |
10369 | instance, under Microsoft Windows symbols must be explicitly imported | |
10370 | from shared libraries (DLLs). | |
10371 | ||
10372 | You need not define this macro if it would always evaluate to zero. | |
a2c4f8e0 | 10373 | @end defmac |
861bb6c1 | 10374 | |
61158923 | 10375 | @deftypefn {Target Hook} tree TARGET_MD_ASM_CLOBBERS (tree @var{outputs}, tree @var{inputs}, tree @var{clobbers}) |
67dfe110 | 10376 | This target hook should add to @var{clobbers} @code{STRING_CST} trees for |
61158923 | 10377 | any hard regs the port wishes to automatically clobber for an asm. |
67dfe110 | 10378 | It should return the result of the last @code{tree_cons} used to add a |
61158923 HPN |
10379 | clobber. The @var{outputs}, @var{inputs} and @var{clobber} lists are the |
10380 | corresponding parameters to the asm and may be inspected to avoid | |
10381 | clobbering a register that is an input or output of the asm. You can use | |
91b4415a | 10382 | @code{tree_overlaps_hard_reg_set}, declared in @file{tree.h}, to test |
61158923 | 10383 | for overlap with regards to asm-declared registers. |
67dfe110 | 10384 | @end deftypefn |
57bcb97a | 10385 | |
a2c4f8e0 | 10386 | @defmac MATH_LIBRARY |
71d718e0 JM |
10387 | Define this macro as a C string constant for the linker argument to link |
10388 | in the system math library, or @samp{""} if the target does not have a | |
10389 | separate math library. | |
10390 | ||
10391 | You need only define this macro if the default of @samp{"-lm"} is wrong. | |
a2c4f8e0 | 10392 | @end defmac |
512b62fb | 10393 | |
a2c4f8e0 | 10394 | @defmac LIBRARY_PATH_ENV |
512b62fb JM |
10395 | Define this macro as a C string constant for the environment variable that |
10396 | specifies where the linker should look for libraries. | |
10397 | ||
10398 | You need only define this macro if the default of @samp{"LIBRARY_PATH"} | |
10399 | is wrong. | |
a2c4f8e0 | 10400 | @end defmac |
e09d24ff | 10401 | |
4969c0d8 L |
10402 | @defmac TARGET_POSIX_IO |
10403 | Define this macro if the target supports the following POSIX@ file | |
10404 | functions, access, mkdir and file locking with fcntl / F_SETLKW@. | |
10405 | Defining @code{TARGET_POSIX_IO} will enable the test coverage code | |
e09d24ff | 10406 | to use file locking when exiting a program, which avoids race conditions |
4969c0d8 | 10407 | if the program has forked. It will also create directories at run-time |
709a840a | 10408 | for cross-profiling. |
a2c4f8e0 | 10409 | @end defmac |
0c99ec5c | 10410 | |
a2c4f8e0 | 10411 | @defmac MAX_CONDITIONAL_EXECUTE |
0c99ec5c RH |
10412 | |
10413 | A C expression for the maximum number of instructions to execute via | |
10414 | conditional execution instructions instead of a branch. A value of | |
10415 | @code{BRANCH_COST}+1 is the default if the machine does not use cc0, and | |
10416 | 1 if it does use cc0. | |
a2c4f8e0 | 10417 | @end defmac |
90280148 | 10418 | |
a2c4f8e0 | 10419 | @defmac IFCVT_MODIFY_TESTS (@var{ce_info}, @var{true_expr}, @var{false_expr}) |
c05ffc49 BS |
10420 | Used if the target needs to perform machine-dependent modifications on the |
10421 | conditionals used for turning basic blocks into conditionally executed code. | |
10422 | @var{ce_info} points to a data structure, @code{struct ce_if_block}, which | |
10423 | contains information about the currently processed blocks. @var{true_expr} | |
10424 | and @var{false_expr} are the tests that are used for converting the | |
10425 | then-block and the else-block, respectively. Set either @var{true_expr} or | |
10426 | @var{false_expr} to a null pointer if the tests cannot be converted. | |
a2c4f8e0 | 10427 | @end defmac |
c05ffc49 | 10428 | |
a2c4f8e0 | 10429 | @defmac IFCVT_MODIFY_MULTIPLE_TESTS (@var{ce_info}, @var{bb}, @var{true_expr}, @var{false_expr}) |
c05ffc49 BS |
10430 | Like @code{IFCVT_MODIFY_TESTS}, but used when converting more complicated |
10431 | if-statements into conditions combined by @code{and} and @code{or} operations. | |
10432 | @var{bb} contains the basic block that contains the test that is currently | |
10433 | being processed and about to be turned into a condition. | |
a2c4f8e0 | 10434 | @end defmac |
90280148 | 10435 | |
a2c4f8e0 | 10436 | @defmac IFCVT_MODIFY_INSN (@var{ce_info}, @var{pattern}, @var{insn}) |
c05ffc49 BS |
10437 | A C expression to modify the @var{PATTERN} of an @var{INSN} that is to |
10438 | be converted to conditional execution format. @var{ce_info} points to | |
10439 | a data structure, @code{struct ce_if_block}, which contains information | |
10440 | about the currently processed blocks. | |
a2c4f8e0 | 10441 | @end defmac |
90280148 | 10442 | |
a2c4f8e0 | 10443 | @defmac IFCVT_MODIFY_FINAL (@var{ce_info}) |
90280148 | 10444 | A C expression to perform any final machine dependent modifications in |
c05ffc49 BS |
10445 | converting code to conditional execution. The involved basic blocks |
10446 | can be found in the @code{struct ce_if_block} structure that is pointed | |
10447 | to by @var{ce_info}. | |
a2c4f8e0 | 10448 | @end defmac |
90280148 | 10449 | |
a2c4f8e0 | 10450 | @defmac IFCVT_MODIFY_CANCEL (@var{ce_info}) |
90280148 | 10451 | A C expression to cancel any machine dependent modifications in |
c05ffc49 BS |
10452 | converting code to conditional execution. The involved basic blocks |
10453 | can be found in the @code{struct ce_if_block} structure that is pointed | |
10454 | to by @var{ce_info}. | |
a2c4f8e0 | 10455 | @end defmac |
c05ffc49 | 10456 | |
a2c4f8e0 | 10457 | @defmac IFCVT_INIT_EXTRA_FIELDS (@var{ce_info}) |
c05ffc49 BS |
10458 | A C expression to initialize any extra fields in a @code{struct ce_if_block} |
10459 | structure, which are defined by the @code{IFCVT_EXTRA_FIELDS} macro. | |
a2c4f8e0 | 10460 | @end defmac |
c05ffc49 | 10461 | |
a2c4f8e0 | 10462 | @defmac IFCVT_EXTRA_FIELDS |
c05ffc49 | 10463 | If defined, it should expand to a set of field declarations that will be |
c0478a66 | 10464 | added to the @code{struct ce_if_block} structure. These should be initialized |
c05ffc49 | 10465 | by the @code{IFCVT_INIT_EXTRA_FIELDS} macro. |
a2c4f8e0 | 10466 | @end defmac |
c05ffc49 | 10467 | |
18dbd950 RS |
10468 | @deftypefn {Target Hook} void TARGET_MACHINE_DEPENDENT_REORG () |
10469 | If non-null, this hook performs a target-specific pass over the | |
10470 | instruction stream. The compiler will run it at all optimization levels, | |
10471 | just before the point at which it normally does delayed-branch scheduling. | |
10472 | ||
10473 | The exact purpose of the hook varies from target to target. Some use | |
10474 | it to do transformations that are necessary for correctness, such as | |
10475 | laying out in-function constant pools or avoiding hardware hazards. | |
10476 | Others use it as an opportunity to do some machine-dependent optimizations. | |
10477 | ||
10478 | You need not implement the hook if it has nothing to do. The default | |
10479 | definition is null. | |
10480 | @end deftypefn | |
10481 | ||
f6155fda SS |
10482 | @deftypefn {Target Hook} void TARGET_INIT_BUILTINS () |
10483 | Define this hook if you have any machine-specific built-in functions | |
10484 | that need to be defined. It should be a function that performs the | |
4a1d48f6 BS |
10485 | necessary setup. |
10486 | ||
c771326b | 10487 | Machine specific built-in functions can be useful to expand special machine |
4a1d48f6 BS |
10488 | instructions that would otherwise not normally be generated because |
10489 | they have no equivalent in the source language (for example, SIMD vector | |
10490 | instructions or prefetch instructions). | |
10491 | ||
6e34d3a3 JM |
10492 | To create a built-in function, call the function |
10493 | @code{lang_hooks.builtin_function} | |
c771326b | 10494 | which is defined by the language front end. You can use any type nodes set |
4a1d48f6 | 10495 | up by @code{build_common_tree_nodes} and @code{build_common_tree_nodes_2}; |
c237e94a | 10496 | only language front ends that use those two functions will call |
f6155fda | 10497 | @samp{TARGET_INIT_BUILTINS}. |
acdcefcc | 10498 | @end deftypefn |
4a1d48f6 | 10499 | |
f6155fda | 10500 | @deftypefn {Target Hook} rtx TARGET_EXPAND_BUILTIN (tree @var{exp}, rtx @var{target}, rtx @var{subtarget}, enum machine_mode @var{mode}, int @var{ignore}) |
4a1d48f6 | 10501 | |
c771326b | 10502 | Expand a call to a machine specific built-in function that was set up by |
f6155fda SS |
10503 | @samp{TARGET_INIT_BUILTINS}. @var{exp} is the expression for the |
10504 | function call; the result should go to @var{target} if that is | |
10505 | convenient, and have mode @var{mode} if that is convenient. | |
10506 | @var{subtarget} may be used as the target for computing one of | |
10507 | @var{exp}'s operands. @var{ignore} is nonzero if the value is to be | |
10508 | ignored. This function should return the result of the call to the | |
10509 | built-in function. | |
acdcefcc | 10510 | @end deftypefn |
4a1d48f6 | 10511 | |
4268e4cf PB |
10512 | @deftypefn {Target Hook} tree TARGET_RESOLVE_OVERLOADED_BUILTIN (tree @var{fndecl}, tree @var{arglist}) |
10513 | ||
10514 | Select a replacement for a machine specific built-in function that | |
10515 | was set up by @samp{TARGET_INIT_BUILTINS}. This is done | |
10516 | @emph{before} regular type checking, and so allows the target to | |
10517 | implement a crude form of function overloading. @var{fndecl} is the | |
10518 | declaration of the built-in function. @var{arglist} is the list of | |
10519 | arguments passed to the built-in function. The result is a | |
10520 | complete expression that implements the operation, usually | |
10521 | another @code{CALL_EXPR}. | |
10522 | @end deftypefn | |
10523 | ||
a05a80fc KH |
10524 | @deftypefn {Target Hook} tree TARGET_FOLD_BUILTIN (tree @var{fndecl}, tree @var{arglist}, bool @var{ignore}) |
10525 | ||
10526 | Fold a call to a machine specific built-in function that was set up by | |
10527 | @samp{TARGET_INIT_BUILTINS}. @var{fndecl} is the declaration of the | |
10528 | built-in function. @var{arglist} is the list of arguments passed to | |
10529 | the built-in function. The result is another tree containing a | |
10530 | simplified expression for the call's result. If @var{ignore} is true | |
10531 | the value will be ignored. | |
d6c2b67d PB |
10532 | @end deftypefn |
10533 | ||
e7e64a25 | 10534 | @deftypefn {Target Hook} const char * TARGET_INVALID_WITHIN_DOLOOP (rtx @var{insn}) |
a71a498d | 10535 | |
e7e64a25 AS |
10536 | Take an instruction in @var{insn} and return NULL if it is valid within a |
10537 | low-overhead loop, otherwise return a string why doloop could not be applied. | |
a71a498d | 10538 | |
e7e64a25 AS |
10539 | Many targets use special registers for low-overhead looping. For any |
10540 | instruction that clobbers these this function should return a string indicating | |
083cad55 | 10541 | the reason why the doloop could not be applied. |
a71a498d | 10542 | By default, the RTL loop optimizer does not use a present doloop pattern for |
083cad55 | 10543 | loops containing function calls or branch on table instructions. |
a71a498d AS |
10544 | @end deftypefn |
10545 | ||
a2c4f8e0 | 10546 | @defmac MD_CAN_REDIRECT_BRANCH (@var{branch1}, @var{branch2}) |
6e7b03e1 | 10547 | |
4fe9b91c | 10548 | Take a branch insn in @var{branch1} and another in @var{branch2}. |
6e7b03e1 AH |
10549 | Return true if redirecting @var{branch1} to the destination of |
10550 | @var{branch2} is possible. | |
10551 | ||
10552 | On some targets, branches may have a limited range. Optimizing the | |
10553 | filling of delay slots can result in branches being redirected, and this | |
10554 | may in turn cause a branch offset to overflow. | |
a2c4f8e0 | 10555 | @end defmac |
6e7b03e1 | 10556 | |
8ddf681a R |
10557 | @deftypefn {Target Hook} bool TARGET_COMMUTATIVE_P (rtx @var{x}, @var{outer_code}) |
10558 | This target hook returns @code{true} if @var{x} is considered to be commutative. | |
10559 | Usually, this is just COMMUTATIVE_P (@var{x}), but the HP PA doesn't consider | |
0ee2ea09 | 10560 | PLUS to be commutative inside a MEM@. @var{outer_code} is the rtx code |
8ddf681a R |
10561 | of the enclosing rtl, if known, otherwise it is UNKNOWN. |
10562 | @end deftypefn | |
10563 | ||
b48f503c | 10564 | @deftypefn {Target Hook} rtx TARGET_ALLOCATE_INITIAL_VALUE (rtx @var{hard_reg}) |
385b6e2d R |
10565 | |
10566 | When the initial value of a hard register has been copied in a pseudo | |
4fe9b91c | 10567 | register, it is often not necessary to actually allocate another register |
385b6e2d | 10568 | to this pseudo register, because the original hard register or a stack slot |
b48f503c KK |
10569 | it has been saved into can be used. @code{TARGET_ALLOCATE_INITIAL_VALUE} |
10570 | is called at the start of register allocation once for each hard register | |
10571 | that had its initial value copied by using | |
385b6e2d R |
10572 | @code{get_func_hard_reg_initial_val} or @code{get_hard_reg_initial_val}. |
10573 | Possible values are @code{NULL_RTX}, if you don't want | |
10574 | to do any special allocation, a @code{REG} rtx---that would typically be | |
10575 | the hard register itself, if it is known not to be clobbered---or a | |
10576 | @code{MEM}. | |
10577 | If you are returning a @code{MEM}, this is only a hint for the allocator; | |
10578 | it might decide to use another register anyways. | |
b48f503c KK |
10579 | You may use @code{current_function_leaf_function} in the hook, functions |
10580 | that use @code{REG_N_SETS}, to determine if the hard | |
385b6e2d | 10581 | register in question will not be clobbered. |
b48f503c KK |
10582 | The default value of this hook is @code{NULL}, which disables any special |
10583 | allocation. | |
10584 | @end deftypefn | |
385b6e2d | 10585 | |
215b063c PB |
10586 | @deftypefn {Target Hook} int TARGET_UNSPEC_MAY_TRAP_P (const_rtx @var{x}, unsigned @var{flags}) |
10587 | This target hook returns nonzero if @var{x}, an @code{unspec} or | |
10588 | @code{unspec_volatile} operation, might cause a trap. Targets can use | |
10589 | this hook to enhance precision of analysis for @code{unspec} and | |
10590 | @code{unspec_volatile} operations. You may call @code{may_trap_p_1} | |
10591 | to analyze inner elements of @var{x} in which case @var{flags} should be | |
10592 | passed along. | |
10593 | @end deftypefn | |
10594 | ||
db2960f4 SL |
10595 | @deftypefn {Target Hook} void TARGET_SET_CURRENT_FUNCTION (tree @var{decl}) |
10596 | The compiler invokes this hook whenever it changes its current function | |
10597 | context (@code{cfun}). You can define this function if | |
10598 | the back end needs to perform any initialization or reset actions on a | |
10599 | per-function basis. For example, it may be used to implement function | |
10600 | attributes that affect register usage or code generation patterns. | |
10601 | The argument @var{decl} is the declaration for the new function context, | |
10602 | and may be null to indicate that the compiler has left a function context | |
10603 | and is returning to processing at the top level. | |
10604 | The default hook function does nothing. | |
10605 | ||
10606 | GCC sets @code{cfun} to a dummy function context during initialization of | |
10607 | some parts of the back end. The hook function is not invoked in this | |
10608 | situation; you need not worry about the hook being invoked recursively, | |
10609 | or when the back end is in a partially-initialized state. | |
10610 | @end deftypefn | |
10611 | ||
a2c4f8e0 | 10612 | @defmac TARGET_OBJECT_SUFFIX |
807633e5 ZW |
10613 | Define this macro to be a C string representing the suffix for object |
10614 | files on your target machine. If you do not define this macro, GCC will | |
10615 | use @samp{.o} as the suffix for object files. | |
a2c4f8e0 | 10616 | @end defmac |
807633e5 | 10617 | |
a2c4f8e0 | 10618 | @defmac TARGET_EXECUTABLE_SUFFIX |
807633e5 ZW |
10619 | Define this macro to be a C string representing the suffix to be |
10620 | automatically added to executable files on your target machine. If you | |
10621 | do not define this macro, GCC will use the null string as the suffix for | |
10622 | executable files. | |
a2c4f8e0 | 10623 | @end defmac |
807633e5 | 10624 | |
a2c4f8e0 | 10625 | @defmac COLLECT_EXPORT_LIST |
807633e5 ZW |
10626 | If defined, @code{collect2} will scan the individual object files |
10627 | specified on its command line and create an export list for the linker. | |
10628 | Define this macro for systems like AIX, where the linker discards | |
10629 | object files that are not referenced from @code{main} and uses export | |
10630 | lists. | |
a2c4f8e0 | 10631 | @end defmac |
807633e5 | 10632 | |
a2c4f8e0 | 10633 | @defmac MODIFY_JNI_METHOD_CALL (@var{mdecl}) |
55ae46b1 RM |
10634 | Define this macro to a C expression representing a variant of the |
10635 | method call @var{mdecl}, if Java Native Interface (JNI) methods | |
10636 | must be invoked differently from other methods on your target. | |
95fef11f | 10637 | For example, on 32-bit Microsoft Windows, JNI methods must be invoked using |
55ae46b1 RM |
10638 | the @code{stdcall} calling convention and this macro is then |
10639 | defined as this expression: | |
10640 | ||
10641 | @smallexample | |
10642 | build_type_attribute_variant (@var{mdecl}, | |
10643 | build_tree_list | |
10644 | (get_identifier ("stdcall"), | |
10645 | NULL)) | |
10646 | @end smallexample | |
a2c4f8e0 | 10647 | @end defmac |
e4ec2cac AO |
10648 | |
10649 | @deftypefn {Target Hook} bool TARGET_CANNOT_MODIFY_JUMPS_P (void) | |
10650 | This target hook returns @code{true} past the point in which new jump | |
10651 | instructions could be created. On machines that require a register for | |
10652 | every jump such as the SHmedia ISA of SH5, this point would typically be | |
10653 | reload, so this target hook should be defined to a function such as: | |
10654 | ||
10655 | @smallexample | |
10656 | static bool | |
10657 | cannot_modify_jumps_past_reload_p () | |
10658 | @{ | |
10659 | return (reload_completed || reload_in_progress); | |
10660 | @} | |
10661 | @end smallexample | |
10662 | @end deftypefn | |
fe3ad572 | 10663 | |
a3424f5c | 10664 | @deftypefn {Target Hook} int TARGET_BRANCH_TARGET_REGISTER_CLASS (void) |
fe3ad572 SC |
10665 | This target hook returns a register class for which branch target register |
10666 | optimizations should be applied. All registers in this class should be | |
c0cbdbd9 | 10667 | usable interchangeably. After reload, registers in this class will be |
fe3ad572 SC |
10668 | re-allocated and loads will be hoisted out of loops and be subjected |
10669 | to inter-block scheduling. | |
10670 | @end deftypefn | |
10671 | ||
10672 | @deftypefn {Target Hook} bool TARGET_BRANCH_TARGET_REGISTER_CALLEE_SAVED (bool @var{after_prologue_epilogue_gen}) | |
10673 | Branch target register optimization will by default exclude callee-saved | |
10674 | registers | |
10675 | that are not already live during the current function; if this target hook | |
10676 | returns true, they will be included. The target code must than make sure | |
10677 | that all target registers in the class returned by | |
10678 | @samp{TARGET_BRANCH_TARGET_REGISTER_CLASS} that might need saving are | |
10679 | saved. @var{after_prologue_epilogue_gen} indicates if prologues and | |
10680 | epilogues have already been generated. Note, even if you only return | |
10681 | true when @var{after_prologue_epilogue_gen} is false, you still are likely | |
10682 | to have to make special provisions in @code{INITIAL_ELIMINATION_OFFSET} | |
10683 | to reserve space for caller-saved target registers. | |
10684 | @end deftypefn | |
2082e02f RS |
10685 | |
10686 | @defmac POWI_MAX_MULTS | |
73774972 | 10687 | If defined, this macro is interpreted as a signed integer C expression |
2082e02f RS |
10688 | that specifies the maximum number of floating point multiplications |
10689 | that should be emitted when expanding exponentiation by an integer | |
10690 | constant inline. When this value is defined, exponentiation requiring | |
10691 | more than this number of multiplications is implemented by calling the | |
10692 | system library's @code{pow}, @code{powf} or @code{powl} routines. | |
10693 | The default value places no upper bound on the multiplication count. | |
10694 | @end defmac | |
94d1613b | 10695 | |
3dd53121 | 10696 | @deftypefn Macro void TARGET_EXTRA_INCLUDES (const char *@var{sysroot}, const char *@var{iprefix}, int @var{stdinc}) |
94d1613b MS |
10697 | This target hook should register any extra include files for the |
10698 | target. The parameter @var{stdinc} indicates if normal include files | |
3dd53121 AP |
10699 | are present. The parameter @var{sysroot} is the system root directory. |
10700 | The parameter @var{iprefix} is the prefix for the gcc directory. | |
10701 | @end deftypefn | |
10702 | ||
10703 | @deftypefn Macro void TARGET_EXTRA_PRE_INCLUDES (const char *@var{sysroot}, const char *@var{iprefix}, int @var{stdinc}) | |
10704 | This target hook should register any extra include files for the | |
10705 | target before any standard headers. The parameter @var{stdinc} | |
10706 | indicates if normal include files are present. The parameter | |
10707 | @var{sysroot} is the system root directory. The parameter | |
10708 | @var{iprefix} is the prefix for the gcc directory. | |
94d1613b MS |
10709 | @end deftypefn |
10710 | ||
10711 | @deftypefn Macro void TARGET_OPTF (char *@var{path}) | |
10712 | This target hook should register special include paths for the target. | |
10713 | The parameter @var{path} is the include to register. On Darwin | |
10714 | systems, this is used for Framework includes, which have semantics | |
10715 | that are different from @option{-I}. | |
10716 | @end deftypefn | |
4a77e08c DS |
10717 | |
10718 | @deftypefn {Target Hook} bool TARGET_USE_LOCAL_THUNK_ALIAS_P (tree @var{fndecl}) | |
10719 | This target hook returns @code{true} if it is safe to use a local alias | |
10720 | for a virtual function @var{fndecl} when constructing thunks, | |
8a36672b | 10721 | @code{false} otherwise. By default, the hook returns @code{true} for all |
431ae0bf | 10722 | functions, if a target supports aliases (i.e.@: defines |
4a77e08c DS |
10723 | @code{ASM_OUTPUT_DEF}), @code{false} otherwise, |
10724 | @end deftypefn | |
a2bec818 DJ |
10725 | |
10726 | @defmac TARGET_FORMAT_TYPES | |
10727 | If defined, this macro is the name of a global variable containing | |
10728 | target-specific format checking information for the @option{-Wformat} | |
10729 | option. The default is to have no target-specific format checks. | |
10730 | @end defmac | |
10731 | ||
10732 | @defmac TARGET_N_FORMAT_TYPES | |
10733 | If defined, this macro is the number of entries in | |
10734 | @code{TARGET_FORMAT_TYPES}. | |
10735 | @end defmac | |
e50e6b88 | 10736 | |
6590fc9f KT |
10737 | @defmac TARGET_OVERRIDES_FORMAT_ATTRIBUTES |
10738 | If defined, this macro is the name of a global variable containing | |
10739 | target-specific format overrides for the @option{-Wformat} option. The | |
10740 | default is to have no target-specific format overrides. If defined, | |
10741 | @code{TARGET_FORMAT_TYPES} must be defined, too. | |
10742 | @end defmac | |
10743 | ||
10744 | @defmac TARGET_OVERRIDES_FORMAT_ATTRIBUTES_COUNT | |
10745 | If defined, this macro specifies the number of entries in | |
10746 | @code{TARGET_OVERRIDES_FORMAT_ATTRIBUTES}. | |
10747 | @end defmac | |
10748 | ||
94564826 KT |
10749 | @defmac TARGET_OVERRIDES_FORMAT_INIT |
10750 | If defined, this macro specifies the optional initialization | |
10751 | routine for target specific customizations of the system printf | |
10752 | and scanf formatter settings. | |
10753 | @end defmac | |
10754 | ||
445cf5eb JM |
10755 | @deftypefn {Target Hook} bool TARGET_RELAXED_ORDERING |
10756 | If set to @code{true}, means that the target's memory model does not | |
10757 | guarantee that loads which do not depend on one another will access | |
10758 | main memory in the order of the instruction stream; if ordering is | |
10759 | important, an explicit memory barrier must be used. This is true of | |
10760 | many recent processors which implement a policy of ``relaxed,'' | |
10761 | ``weak,'' or ``release'' memory consistency, such as Alpha, PowerPC, | |
10762 | and ia64. The default is @code{false}. | |
10763 | @end deftypefn | |
10764 | ||
4d3e6fae | 10765 | @deftypefn {Target Hook} const char *TARGET_INVALID_ARG_FOR_UNPROTOTYPED_FN (tree @var{typelist}, tree @var{funcdecl}, tree @var{val}) |
083cad55 EC |
10766 | If defined, this macro returns the diagnostic message when it is |
10767 | illegal to pass argument @var{val} to function @var{funcdecl} | |
4d3e6fae FJ |
10768 | with prototype @var{typelist}. |
10769 | @end deftypefn | |
10770 | ||
4de67c26 JM |
10771 | @deftypefn {Target Hook} {const char *} TARGET_INVALID_CONVERSION (tree @var{fromtype}, tree @var{totype}) |
10772 | If defined, this macro returns the diagnostic message when it is | |
10773 | invalid to convert from @var{fromtype} to @var{totype}, or @code{NULL} | |
10774 | if validity should be determined by the front end. | |
10775 | @end deftypefn | |
10776 | ||
10777 | @deftypefn {Target Hook} {const char *} TARGET_INVALID_UNARY_OP (int @var{op}, tree @var{type}) | |
10778 | If defined, this macro returns the diagnostic message when it is | |
10779 | invalid to apply operation @var{op} (where unary plus is denoted by | |
10780 | @code{CONVERT_EXPR}) to an operand of type @var{type}, or @code{NULL} | |
10781 | if validity should be determined by the front end. | |
10782 | @end deftypefn | |
10783 | ||
10784 | @deftypefn {Target Hook} {const char *} TARGET_INVALID_BINARY_OP (int @var{op}, tree @var{type1}, tree @var{type2}) | |
10785 | If defined, this macro returns the diagnostic message when it is | |
10786 | invalid to apply operation @var{op} to operands of types @var{type1} | |
10787 | and @var{type2}, or @code{NULL} if validity should be determined by | |
10788 | the front end. | |
10789 | @end deftypefn | |
10790 | ||
40449a90 SL |
10791 | @deftypefn {Target Hook} {const char *} TARGET_INVALID_PARAMETER_TYPE (tree @var{type}) |
10792 | If defined, this macro returns the diagnostic message when it is | |
10793 | invalid for functions to include parameters of type @var{type}, | |
10794 | or @code{NULL} if validity should be determined by | |
10795 | the front end. This is currently used only by the C and C++ front ends. | |
10796 | @end deftypefn | |
10797 | ||
10798 | @deftypefn {Target Hook} {const char *} TARGET_INVALID_RETURN_TYPE (tree @var{type}) | |
10799 | If defined, this macro returns the diagnostic message when it is | |
10800 | invalid for functions to have return type @var{type}, | |
10801 | or @code{NULL} if validity should be determined by | |
10802 | the front end. This is currently used only by the C and C++ front ends. | |
10803 | @end deftypefn | |
10804 | ||
10805 | @deftypefn {Target Hook} {tree} TARGET_PROMOTED_TYPE (tree @var{type}) | |
10806 | If defined, this target hook returns the type to which values of | |
10807 | @var{type} should be promoted when they appear in expressions, | |
10808 | analogous to the integer promotions, or @code{NULL_TREE} to use the | |
10809 | front end's normal promotion rules. This hook is useful when there are | |
10810 | target-specific types with special promotion rules. | |
10811 | This is currently used only by the C and C++ front ends. | |
10812 | @end deftypefn | |
10813 | ||
10814 | @deftypefn {Target Hook} {tree} TARGET_CONVERT_TO_TYPE (tree @var{type}, tree @var{expr}) | |
10815 | If defined, this hook returns the result of converting @var{expr} to | |
10816 | @var{type}. It should return the converted expression, | |
10817 | or @code{NULL_TREE} to apply the front end's normal conversion rules. | |
10818 | This hook is useful when there are target-specific types with special | |
10819 | conversion rules. | |
10820 | This is currently used only by the C and C++ front ends. | |
10821 | @end deftypefn | |
10822 | ||
e50e6b88 DS |
10823 | @defmac TARGET_USE_JCR_SECTION |
10824 | This macro determines whether to use the JCR section to register Java | |
10825 | classes. By default, TARGET_USE_JCR_SECTION is defined to 1 if both | |
10826 | SUPPORTS_WEAK and TARGET_HAVE_NAMED_SECTIONS are true, else 0. | |
10827 | @end defmac | |
64ee9490 EC |
10828 | |
10829 | @defmac OBJC_JBLEN | |
10830 | This macro determines the size of the objective C jump buffer for the | |
10831 | NeXT runtime. By default, OBJC_JBLEN is defined to an innocuous value. | |
10832 | @end defmac | |
56e449d3 SL |
10833 | |
10834 | @defmac LIBGCC2_UNWIND_ATTRIBUTE | |
10835 | Define this macro if any target-specific attributes need to be attached | |
10836 | to the functions in @file{libgcc} that provide low-level support for | |
10837 | call stack unwinding. It is used in declarations in @file{unwind-generic.h} | |
10838 | and the associated definitions of those functions. | |
10839 | @end defmac | |
007e61c2 | 10840 | |
2e3f842f L |
10841 | @deftypefn {Target Hook} void TARGET_UPDATE_STACK_BOUNDARY (void) |
10842 | Define this macro to update the current function stack boundary if | |
10843 | necessary. | |
10844 | @end deftypefn | |
10845 | ||
10846 | @deftypefn {Target Hook} rtx TARGET_GET_DRAP_RTX (void) | |
10847 | Define this macro to an rtx for Dynamic Realign Argument Pointer if a | |
10848 | different argument pointer register is needed to access the function's | |
10849 | argument list when stack is aligned. | |
10850 | @end deftypefn | |
10851 | ||
007e61c2 PB |
10852 | @deftypefn {Target Hook} {bool} TARGET_ALLOCATE_STACK_SLOTS_FOR_ARGS (void) |
10853 | When optimization is disabled, this hook indicates whether or not | |
10854 | arguments should be allocated to stack slots. Normally, GCC allocates | |
10855 | stacks slots for arguments when not optimizing in order to make | |
10856 | debugging easier. However, when a function is declared with | |
10857 | @code{__attribute__((naked))}, there is no stack frame, and the compiler | |
10858 | cannot safely move arguments from the registers in which they are passed | |
10859 | to the stack. Therefore, this hook should return true in general, but | |
10860 | false for naked functions. The default implementation always returns true. | |
10861 | @end deftypefn | |
2c5bfdf7 AN |
10862 | |
10863 | ||
10864 | @deftypevr {Target Hook} {unsigned HOST_WIDE_INT} TARGET_CONST_ANCHOR | |
10865 | On some architectures it can take multiple instructions to synthesize | |
10866 | a constant. If there is another constant already in a register that | |
10867 | is close enough in value then it is preferable that the new constant | |
10868 | is computed from this register using immediate addition or | |
10869 | substraction. We accomplish this through CSE. Besides the value of | |
10870 | the constant we also add a lower and an upper constant anchor to the | |
10871 | available expressions. These are then queried when encountering new | |
10872 | constants. The anchors are computed by rounding the constant up and | |
10873 | down to a multiple of the value of @code{TARGET_CONST_ANCHOR}. | |
10874 | @code{TARGET_CONST_ANCHOR} should be the maximum positive value | |
10875 | accepted by immediate-add plus one. We currently assume that the | |
10876 | value of @code{TARGET_CONST_ANCHOR} is a power of 2. For example, on | |
10877 | MIPS, where add-immediate takes a 16-bit signed value, | |
10878 | @code{TARGET_CONST_ANCHOR} is set to @samp{0x8000}. The default value | |
10879 | is zero, which disables this optimization. @end deftypevr |