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cbe34bb5 | 1 | @c Copyright (C) 1988-2017 Free Software Foundation, Inc. |
03dda8e3 RK |
2 | @c This is part of the GCC manual. |
3 | @c For copying conditions, see the file gcc.texi. | |
4 | ||
5 | @ifset INTERNALS | |
6 | @node Machine Desc | |
7 | @chapter Machine Descriptions | |
8 | @cindex machine descriptions | |
9 | ||
10 | A machine description has two parts: a file of instruction patterns | |
11 | (@file{.md} file) and a C header file of macro definitions. | |
12 | ||
13 | The @file{.md} file for a target machine contains a pattern for each | |
14 | instruction that the target machine supports (or at least each instruction | |
15 | that is worth telling the compiler about). It may also contain comments. | |
16 | A semicolon causes the rest of the line to be a comment, unless the semicolon | |
17 | is inside a quoted string. | |
18 | ||
19 | See the next chapter for information on the C header file. | |
20 | ||
21 | @menu | |
55e4756f | 22 | * Overview:: How the machine description is used. |
03dda8e3 RK |
23 | * Patterns:: How to write instruction patterns. |
24 | * Example:: An explained example of a @code{define_insn} pattern. | |
25 | * RTL Template:: The RTL template defines what insns match a pattern. | |
26 | * Output Template:: The output template says how to make assembler code | |
6ccde948 | 27 | from such an insn. |
03dda8e3 | 28 | * Output Statement:: For more generality, write C code to output |
6ccde948 | 29 | the assembler code. |
e543e219 | 30 | * Predicates:: Controlling what kinds of operands can be used |
6ccde948 | 31 | for an insn. |
e543e219 | 32 | * Constraints:: Fine-tuning operand selection. |
03dda8e3 RK |
33 | * Standard Names:: Names mark patterns to use for code generation. |
34 | * Pattern Ordering:: When the order of patterns makes a difference. | |
35 | * Dependent Patterns:: Having one pattern may make you need another. | |
36 | * Jump Patterns:: Special considerations for patterns for jump insns. | |
6e4fcc95 | 37 | * Looping Patterns:: How to define patterns for special looping insns. |
03dda8e3 | 38 | * Insn Canonicalizations::Canonicalization of Instructions |
03dda8e3 | 39 | * Expander Definitions::Generating a sequence of several RTL insns |
6ccde948 | 40 | for a standard operation. |
f3a3d0d3 | 41 | * Insn Splitting:: Splitting Instructions into Multiple Instructions. |
6ccde948 | 42 | * Including Patterns:: Including Patterns in Machine Descriptions. |
f3a3d0d3 | 43 | * Peephole Definitions::Defining machine-specific peephole optimizations. |
03dda8e3 | 44 | * Insn Attributes:: Specifying the value of attributes for generated insns. |
3262c1f5 | 45 | * Conditional Execution::Generating @code{define_insn} patterns for |
6ccde948 | 46 | predication. |
477c104e MK |
47 | * Define Subst:: Generating @code{define_insn} and @code{define_expand} |
48 | patterns from other patterns. | |
c25c12b8 R |
49 | * Constant Definitions::Defining symbolic constants that can be used in the |
50 | md file. | |
3abcb3a7 | 51 | * Iterators:: Using iterators to generate patterns from a template. |
03dda8e3 RK |
52 | @end menu |
53 | ||
55e4756f DD |
54 | @node Overview |
55 | @section Overview of How the Machine Description is Used | |
56 | ||
57 | There are three main conversions that happen in the compiler: | |
58 | ||
59 | @enumerate | |
60 | ||
61 | @item | |
62 | The front end reads the source code and builds a parse tree. | |
63 | ||
64 | @item | |
65 | The parse tree is used to generate an RTL insn list based on named | |
66 | instruction patterns. | |
67 | ||
68 | @item | |
69 | The insn list is matched against the RTL templates to produce assembler | |
70 | code. | |
71 | ||
72 | @end enumerate | |
73 | ||
74 | For the generate pass, only the names of the insns matter, from either a | |
75 | named @code{define_insn} or a @code{define_expand}. The compiler will | |
76 | choose the pattern with the right name and apply the operands according | |
77 | to the documentation later in this chapter, without regard for the RTL | |
78 | template or operand constraints. Note that the names the compiler looks | |
d7d9c429 | 79 | for are hard-coded in the compiler---it will ignore unnamed patterns and |
55e4756f DD |
80 | patterns with names it doesn't know about, but if you don't provide a |
81 | named pattern it needs, it will abort. | |
82 | ||
83 | If a @code{define_insn} is used, the template given is inserted into the | |
84 | insn list. If a @code{define_expand} is used, one of three things | |
85 | happens, based on the condition logic. The condition logic may manually | |
86 | create new insns for the insn list, say via @code{emit_insn()}, and | |
aee96fe9 | 87 | invoke @code{DONE}. For certain named patterns, it may invoke @code{FAIL} to tell the |
55e4756f DD |
88 | compiler to use an alternate way of performing that task. If it invokes |
89 | neither @code{DONE} nor @code{FAIL}, the template given in the pattern | |
90 | is inserted, as if the @code{define_expand} were a @code{define_insn}. | |
91 | ||
92 | Once the insn list is generated, various optimization passes convert, | |
93 | replace, and rearrange the insns in the insn list. This is where the | |
94 | @code{define_split} and @code{define_peephole} patterns get used, for | |
95 | example. | |
96 | ||
97 | Finally, the insn list's RTL is matched up with the RTL templates in the | |
98 | @code{define_insn} patterns, and those patterns are used to emit the | |
99 | final assembly code. For this purpose, each named @code{define_insn} | |
100 | acts like it's unnamed, since the names are ignored. | |
101 | ||
03dda8e3 RK |
102 | @node Patterns |
103 | @section Everything about Instruction Patterns | |
104 | @cindex patterns | |
105 | @cindex instruction patterns | |
106 | ||
107 | @findex define_insn | |
2f9d3709 JG |
108 | A @code{define_insn} expression is used to define instruction patterns |
109 | to which insns may be matched. A @code{define_insn} expression contains | |
110 | an incomplete RTL expression, with pieces to be filled in later, operand | |
111 | constraints that restrict how the pieces can be filled in, and an output | |
112 | template or C code to generate the assembler output. | |
03dda8e3 RK |
113 | |
114 | A @code{define_insn} is an RTL expression containing four or five operands: | |
115 | ||
116 | @enumerate | |
117 | @item | |
49e478af | 118 | An optional name. The presence of a name indicates that this instruction |
03dda8e3 RK |
119 | pattern can perform a certain standard job for the RTL-generation |
120 | pass of the compiler. This pass knows certain names and will use | |
121 | the instruction patterns with those names, if the names are defined | |
122 | in the machine description. | |
123 | ||
124 | The absence of a name is indicated by writing an empty string | |
125 | where the name should go. Nameless instruction patterns are never | |
126 | used for generating RTL code, but they may permit several simpler insns | |
127 | to be combined later on. | |
128 | ||
129 | Names that are not thus known and used in RTL-generation have no | |
130 | effect; they are equivalent to no name at all. | |
131 | ||
661cb0b7 RK |
132 | For the purpose of debugging the compiler, you may also specify a |
133 | name beginning with the @samp{*} character. Such a name is used only | |
2f9d3709 JG |
134 | for identifying the instruction in RTL dumps; it is equivalent to having |
135 | a nameless pattern for all other purposes. Names beginning with the | |
136 | @samp{*} character are not required to be unique. | |
661cb0b7 | 137 | |
03dda8e3 | 138 | @item |
2f9d3709 JG |
139 | The @dfn{RTL template}: This is a vector of incomplete RTL expressions |
140 | which describe the semantics of the instruction (@pxref{RTL Template}). | |
141 | It is incomplete because it may contain @code{match_operand}, | |
03dda8e3 RK |
142 | @code{match_operator}, and @code{match_dup} expressions that stand for |
143 | operands of the instruction. | |
144 | ||
2f9d3709 JG |
145 | If the vector has multiple elements, the RTL template is treated as a |
146 | @code{parallel} expression. | |
03dda8e3 RK |
147 | |
148 | @item | |
149 | @cindex pattern conditions | |
150 | @cindex conditions, in patterns | |
2f9d3709 JG |
151 | The condition: This is a string which contains a C expression. When the |
152 | compiler attempts to match RTL against a pattern, the condition is | |
153 | evaluated. If the condition evaluates to @code{true}, the match is | |
154 | permitted. The condition may be an empty string, which is treated | |
155 | as always @code{true}. | |
03dda8e3 RK |
156 | |
157 | @cindex named patterns and conditions | |
2f9d3709 JG |
158 | For a named pattern, the condition may not depend on the data in the |
159 | insn being matched, but only the target-machine-type flags. The compiler | |
160 | needs to test these conditions during initialization in order to learn | |
161 | exactly which named instructions are available in a particular run. | |
03dda8e3 RK |
162 | |
163 | @findex operands | |
164 | For nameless patterns, the condition is applied only when matching an | |
165 | individual insn, and only after the insn has matched the pattern's | |
166 | recognition template. The insn's operands may be found in the vector | |
2f9d3709 JG |
167 | @code{operands}. |
168 | ||
49e478af RS |
169 | An instruction condition cannot become more restrictive as compilation |
170 | progresses. If the condition accepts a particular RTL instruction at | |
171 | one stage of compilation, it must continue to accept that instruction | |
172 | until the final pass. For example, @samp{!reload_completed} and | |
173 | @samp{can_create_pseudo_p ()} are both invalid instruction conditions, | |
174 | because they are true during the earlier RTL passes and false during | |
175 | the later ones. For the same reason, if a condition accepts an | |
176 | instruction before register allocation, it cannot later try to control | |
177 | register allocation by excluding certain register or value combinations. | |
178 | ||
179 | Although a condition cannot become more restrictive as compilation | |
180 | progresses, the condition for a nameless pattern @emph{can} become | |
181 | more permissive. For example, a nameless instruction can require | |
182 | @samp{reload_completed} to be true, in which case it only matches | |
183 | after register allocation. | |
03dda8e3 RK |
184 | |
185 | @item | |
2f9d3709 JG |
186 | The @dfn{output template} or @dfn{output statement}: This is either |
187 | a string, or a fragment of C code which returns a string. | |
03dda8e3 RK |
188 | |
189 | When simple substitution isn't general enough, you can specify a piece | |
190 | of C code to compute the output. @xref{Output Statement}. | |
191 | ||
192 | @item | |
2f9d3709 JG |
193 | The @dfn{insn attributes}: This is an optional vector containing the values of |
194 | attributes for insns matching this pattern (@pxref{Insn Attributes}). | |
03dda8e3 RK |
195 | @end enumerate |
196 | ||
197 | @node Example | |
198 | @section Example of @code{define_insn} | |
199 | @cindex @code{define_insn} example | |
200 | ||
2f9d3709 JG |
201 | Here is an example of an instruction pattern, taken from the machine |
202 | description for the 68000/68020. | |
03dda8e3 | 203 | |
3ab51846 | 204 | @smallexample |
03dda8e3 RK |
205 | (define_insn "tstsi" |
206 | [(set (cc0) | |
207 | (match_operand:SI 0 "general_operand" "rm"))] | |
208 | "" | |
209 | "* | |
f282ffb3 | 210 | @{ |
0f40f9f7 | 211 | if (TARGET_68020 || ! ADDRESS_REG_P (operands[0])) |
03dda8e3 | 212 | return \"tstl %0\"; |
f282ffb3 | 213 | return \"cmpl #0,%0\"; |
0f40f9f7 | 214 | @}") |
3ab51846 | 215 | @end smallexample |
0f40f9f7 ZW |
216 | |
217 | @noindent | |
218 | This can also be written using braced strings: | |
219 | ||
3ab51846 | 220 | @smallexample |
0f40f9f7 ZW |
221 | (define_insn "tstsi" |
222 | [(set (cc0) | |
223 | (match_operand:SI 0 "general_operand" "rm"))] | |
224 | "" | |
f282ffb3 | 225 | @{ |
0f40f9f7 ZW |
226 | if (TARGET_68020 || ! ADDRESS_REG_P (operands[0])) |
227 | return "tstl %0"; | |
f282ffb3 | 228 | return "cmpl #0,%0"; |
0f40f9f7 | 229 | @}) |
3ab51846 | 230 | @end smallexample |
03dda8e3 | 231 | |
2f9d3709 JG |
232 | This describes an instruction which sets the condition codes based on the |
233 | value of a general operand. It has no condition, so any insn with an RTL | |
234 | description of the form shown may be matched to this pattern. The name | |
235 | @samp{tstsi} means ``test a @code{SImode} value'' and tells the RTL | |
236 | generation pass that, when it is necessary to test such a value, an insn | |
237 | to do so can be constructed using this pattern. | |
03dda8e3 RK |
238 | |
239 | The output control string is a piece of C code which chooses which | |
240 | output template to return based on the kind of operand and the specific | |
241 | type of CPU for which code is being generated. | |
242 | ||
243 | @samp{"rm"} is an operand constraint. Its meaning is explained below. | |
244 | ||
245 | @node RTL Template | |
246 | @section RTL Template | |
247 | @cindex RTL insn template | |
248 | @cindex generating insns | |
249 | @cindex insns, generating | |
250 | @cindex recognizing insns | |
251 | @cindex insns, recognizing | |
252 | ||
253 | The RTL template is used to define which insns match the particular pattern | |
254 | and how to find their operands. For named patterns, the RTL template also | |
255 | says how to construct an insn from specified operands. | |
256 | ||
257 | Construction involves substituting specified operands into a copy of the | |
258 | template. Matching involves determining the values that serve as the | |
259 | operands in the insn being matched. Both of these activities are | |
260 | controlled by special expression types that direct matching and | |
261 | substitution of the operands. | |
262 | ||
263 | @table @code | |
264 | @findex match_operand | |
265 | @item (match_operand:@var{m} @var{n} @var{predicate} @var{constraint}) | |
266 | This expression is a placeholder for operand number @var{n} of | |
267 | the insn. When constructing an insn, operand number @var{n} | |
268 | will be substituted at this point. When matching an insn, whatever | |
269 | appears at this position in the insn will be taken as operand | |
270 | number @var{n}; but it must satisfy @var{predicate} or this instruction | |
271 | pattern will not match at all. | |
272 | ||
273 | Operand numbers must be chosen consecutively counting from zero in | |
274 | each instruction pattern. There may be only one @code{match_operand} | |
275 | expression in the pattern for each operand number. Usually operands | |
276 | are numbered in the order of appearance in @code{match_operand} | |
72938a4c MM |
277 | expressions. In the case of a @code{define_expand}, any operand numbers |
278 | used only in @code{match_dup} expressions have higher values than all | |
279 | other operand numbers. | |
03dda8e3 | 280 | |
e543e219 ZW |
281 | @var{predicate} is a string that is the name of a function that |
282 | accepts two arguments, an expression and a machine mode. | |
283 | @xref{Predicates}. During matching, the function will be called with | |
284 | the putative operand as the expression and @var{m} as the mode | |
285 | argument (if @var{m} is not specified, @code{VOIDmode} will be used, | |
286 | which normally causes @var{predicate} to accept any mode). If it | |
287 | returns zero, this instruction pattern fails to match. | |
288 | @var{predicate} may be an empty string; then it means no test is to be | |
289 | done on the operand, so anything which occurs in this position is | |
290 | valid. | |
03dda8e3 RK |
291 | |
292 | Most of the time, @var{predicate} will reject modes other than @var{m}---but | |
293 | not always. For example, the predicate @code{address_operand} uses | |
294 | @var{m} as the mode of memory ref that the address should be valid for. | |
295 | Many predicates accept @code{const_int} nodes even though their mode is | |
296 | @code{VOIDmode}. | |
297 | ||
298 | @var{constraint} controls reloading and the choice of the best register | |
299 | class to use for a value, as explained later (@pxref{Constraints}). | |
e543e219 | 300 | If the constraint would be an empty string, it can be omitted. |
03dda8e3 RK |
301 | |
302 | People are often unclear on the difference between the constraint and the | |
303 | predicate. The predicate helps decide whether a given insn matches the | |
304 | pattern. The constraint plays no role in this decision; instead, it | |
305 | controls various decisions in the case of an insn which does match. | |
306 | ||
03dda8e3 RK |
307 | @findex match_scratch |
308 | @item (match_scratch:@var{m} @var{n} @var{constraint}) | |
309 | This expression is also a placeholder for operand number @var{n} | |
310 | and indicates that operand must be a @code{scratch} or @code{reg} | |
311 | expression. | |
312 | ||
313 | When matching patterns, this is equivalent to | |
314 | ||
315 | @smallexample | |
e80f9fef | 316 | (match_operand:@var{m} @var{n} "scratch_operand" @var{constraint}) |
03dda8e3 RK |
317 | @end smallexample |
318 | ||
319 | but, when generating RTL, it produces a (@code{scratch}:@var{m}) | |
320 | expression. | |
321 | ||
322 | If the last few expressions in a @code{parallel} are @code{clobber} | |
323 | expressions whose operands are either a hard register or | |
324 | @code{match_scratch}, the combiner can add or delete them when | |
325 | necessary. @xref{Side Effects}. | |
326 | ||
327 | @findex match_dup | |
328 | @item (match_dup @var{n}) | |
329 | This expression is also a placeholder for operand number @var{n}. | |
330 | It is used when the operand needs to appear more than once in the | |
331 | insn. | |
332 | ||
333 | In construction, @code{match_dup} acts just like @code{match_operand}: | |
334 | the operand is substituted into the insn being constructed. But in | |
335 | matching, @code{match_dup} behaves differently. It assumes that operand | |
336 | number @var{n} has already been determined by a @code{match_operand} | |
337 | appearing earlier in the recognition template, and it matches only an | |
338 | identical-looking expression. | |
339 | ||
55e4756f DD |
340 | Note that @code{match_dup} should not be used to tell the compiler that |
341 | a particular register is being used for two operands (example: | |
342 | @code{add} that adds one register to another; the second register is | |
343 | both an input operand and the output operand). Use a matching | |
344 | constraint (@pxref{Simple Constraints}) for those. @code{match_dup} is for the cases where one | |
345 | operand is used in two places in the template, such as an instruction | |
346 | that computes both a quotient and a remainder, where the opcode takes | |
347 | two input operands but the RTL template has to refer to each of those | |
348 | twice; once for the quotient pattern and once for the remainder pattern. | |
349 | ||
03dda8e3 RK |
350 | @findex match_operator |
351 | @item (match_operator:@var{m} @var{n} @var{predicate} [@var{operands}@dots{}]) | |
352 | This pattern is a kind of placeholder for a variable RTL expression | |
353 | code. | |
354 | ||
355 | When constructing an insn, it stands for an RTL expression whose | |
356 | expression code is taken from that of operand @var{n}, and whose | |
357 | operands are constructed from the patterns @var{operands}. | |
358 | ||
359 | When matching an expression, it matches an expression if the function | |
360 | @var{predicate} returns nonzero on that expression @emph{and} the | |
361 | patterns @var{operands} match the operands of the expression. | |
362 | ||
363 | Suppose that the function @code{commutative_operator} is defined as | |
364 | follows, to match any expression whose operator is one of the | |
365 | commutative arithmetic operators of RTL and whose mode is @var{mode}: | |
366 | ||
367 | @smallexample | |
368 | int | |
ec8e098d | 369 | commutative_integer_operator (x, mode) |
03dda8e3 | 370 | rtx x; |
ef4bddc2 | 371 | machine_mode mode; |
03dda8e3 RK |
372 | @{ |
373 | enum rtx_code code = GET_CODE (x); | |
374 | if (GET_MODE (x) != mode) | |
375 | return 0; | |
ec8e098d | 376 | return (GET_RTX_CLASS (code) == RTX_COMM_ARITH |
03dda8e3 RK |
377 | || code == EQ || code == NE); |
378 | @} | |
379 | @end smallexample | |
380 | ||
381 | Then the following pattern will match any RTL expression consisting | |
382 | of a commutative operator applied to two general operands: | |
383 | ||
384 | @smallexample | |
385 | (match_operator:SI 3 "commutative_operator" | |
386 | [(match_operand:SI 1 "general_operand" "g") | |
387 | (match_operand:SI 2 "general_operand" "g")]) | |
388 | @end smallexample | |
389 | ||
390 | Here the vector @code{[@var{operands}@dots{}]} contains two patterns | |
391 | because the expressions to be matched all contain two operands. | |
392 | ||
393 | When this pattern does match, the two operands of the commutative | |
394 | operator are recorded as operands 1 and 2 of the insn. (This is done | |
395 | by the two instances of @code{match_operand}.) Operand 3 of the insn | |
396 | will be the entire commutative expression: use @code{GET_CODE | |
397 | (operands[3])} to see which commutative operator was used. | |
398 | ||
399 | The machine mode @var{m} of @code{match_operator} works like that of | |
400 | @code{match_operand}: it is passed as the second argument to the | |
401 | predicate function, and that function is solely responsible for | |
402 | deciding whether the expression to be matched ``has'' that mode. | |
403 | ||
404 | When constructing an insn, argument 3 of the gen-function will specify | |
e979f9e8 | 405 | the operation (i.e.@: the expression code) for the expression to be |
03dda8e3 RK |
406 | made. It should be an RTL expression, whose expression code is copied |
407 | into a new expression whose operands are arguments 1 and 2 of the | |
408 | gen-function. The subexpressions of argument 3 are not used; | |
409 | only its expression code matters. | |
410 | ||
411 | When @code{match_operator} is used in a pattern for matching an insn, | |
412 | it usually best if the operand number of the @code{match_operator} | |
413 | is higher than that of the actual operands of the insn. This improves | |
414 | register allocation because the register allocator often looks at | |
415 | operands 1 and 2 of insns to see if it can do register tying. | |
416 | ||
417 | There is no way to specify constraints in @code{match_operator}. The | |
418 | operand of the insn which corresponds to the @code{match_operator} | |
419 | never has any constraints because it is never reloaded as a whole. | |
420 | However, if parts of its @var{operands} are matched by | |
421 | @code{match_operand} patterns, those parts may have constraints of | |
422 | their own. | |
423 | ||
424 | @findex match_op_dup | |
425 | @item (match_op_dup:@var{m} @var{n}[@var{operands}@dots{}]) | |
426 | Like @code{match_dup}, except that it applies to operators instead of | |
427 | operands. When constructing an insn, operand number @var{n} will be | |
428 | substituted at this point. But in matching, @code{match_op_dup} behaves | |
429 | differently. It assumes that operand number @var{n} has already been | |
430 | determined by a @code{match_operator} appearing earlier in the | |
431 | recognition template, and it matches only an identical-looking | |
432 | expression. | |
433 | ||
434 | @findex match_parallel | |
435 | @item (match_parallel @var{n} @var{predicate} [@var{subpat}@dots{}]) | |
436 | This pattern is a placeholder for an insn that consists of a | |
437 | @code{parallel} expression with a variable number of elements. This | |
438 | expression should only appear at the top level of an insn pattern. | |
439 | ||
440 | When constructing an insn, operand number @var{n} will be substituted at | |
441 | this point. When matching an insn, it matches if the body of the insn | |
442 | is a @code{parallel} expression with at least as many elements as the | |
443 | vector of @var{subpat} expressions in the @code{match_parallel}, if each | |
444 | @var{subpat} matches the corresponding element of the @code{parallel}, | |
445 | @emph{and} the function @var{predicate} returns nonzero on the | |
446 | @code{parallel} that is the body of the insn. It is the responsibility | |
447 | of the predicate to validate elements of the @code{parallel} beyond | |
bd819a4a | 448 | those listed in the @code{match_parallel}. |
03dda8e3 RK |
449 | |
450 | A typical use of @code{match_parallel} is to match load and store | |
451 | multiple expressions, which can contain a variable number of elements | |
452 | in a @code{parallel}. For example, | |
03dda8e3 RK |
453 | |
454 | @smallexample | |
455 | (define_insn "" | |
456 | [(match_parallel 0 "load_multiple_operation" | |
457 | [(set (match_operand:SI 1 "gpc_reg_operand" "=r") | |
458 | (match_operand:SI 2 "memory_operand" "m")) | |
459 | (use (reg:SI 179)) | |
460 | (clobber (reg:SI 179))])] | |
461 | "" | |
462 | "loadm 0,0,%1,%2") | |
463 | @end smallexample | |
464 | ||
465 | This example comes from @file{a29k.md}. The function | |
9c34dbbf | 466 | @code{load_multiple_operation} is defined in @file{a29k.c} and checks |
03dda8e3 RK |
467 | that subsequent elements in the @code{parallel} are the same as the |
468 | @code{set} in the pattern, except that they are referencing subsequent | |
469 | registers and memory locations. | |
470 | ||
471 | An insn that matches this pattern might look like: | |
472 | ||
473 | @smallexample | |
474 | (parallel | |
475 | [(set (reg:SI 20) (mem:SI (reg:SI 100))) | |
476 | (use (reg:SI 179)) | |
477 | (clobber (reg:SI 179)) | |
478 | (set (reg:SI 21) | |
479 | (mem:SI (plus:SI (reg:SI 100) | |
480 | (const_int 4)))) | |
481 | (set (reg:SI 22) | |
482 | (mem:SI (plus:SI (reg:SI 100) | |
483 | (const_int 8))))]) | |
484 | @end smallexample | |
485 | ||
486 | @findex match_par_dup | |
487 | @item (match_par_dup @var{n} [@var{subpat}@dots{}]) | |
488 | Like @code{match_op_dup}, but for @code{match_parallel} instead of | |
489 | @code{match_operator}. | |
490 | ||
03dda8e3 RK |
491 | @end table |
492 | ||
493 | @node Output Template | |
494 | @section Output Templates and Operand Substitution | |
495 | @cindex output templates | |
496 | @cindex operand substitution | |
497 | ||
498 | @cindex @samp{%} in template | |
499 | @cindex percent sign | |
500 | The @dfn{output template} is a string which specifies how to output the | |
501 | assembler code for an instruction pattern. Most of the template is a | |
502 | fixed string which is output literally. The character @samp{%} is used | |
503 | to specify where to substitute an operand; it can also be used to | |
504 | identify places where different variants of the assembler require | |
505 | different syntax. | |
506 | ||
507 | In the simplest case, a @samp{%} followed by a digit @var{n} says to output | |
508 | operand @var{n} at that point in the string. | |
509 | ||
510 | @samp{%} followed by a letter and a digit says to output an operand in an | |
511 | alternate fashion. Four letters have standard, built-in meanings described | |
512 | below. The machine description macro @code{PRINT_OPERAND} can define | |
513 | additional letters with nonstandard meanings. | |
514 | ||
515 | @samp{%c@var{digit}} can be used to substitute an operand that is a | |
516 | constant value without the syntax that normally indicates an immediate | |
517 | operand. | |
518 | ||
519 | @samp{%n@var{digit}} is like @samp{%c@var{digit}} except that the value of | |
520 | the constant is negated before printing. | |
521 | ||
522 | @samp{%a@var{digit}} can be used to substitute an operand as if it were a | |
523 | memory reference, with the actual operand treated as the address. This may | |
524 | be useful when outputting a ``load address'' instruction, because often the | |
525 | assembler syntax for such an instruction requires you to write the operand | |
526 | as if it were a memory reference. | |
527 | ||
528 | @samp{%l@var{digit}} is used to substitute a @code{label_ref} into a jump | |
529 | instruction. | |
530 | ||
531 | @samp{%=} outputs a number which is unique to each instruction in the | |
532 | entire compilation. This is useful for making local labels to be | |
533 | referred to more than once in a single template that generates multiple | |
534 | assembler instructions. | |
535 | ||
536 | @samp{%} followed by a punctuation character specifies a substitution that | |
537 | does not use an operand. Only one case is standard: @samp{%%} outputs a | |
538 | @samp{%} into the assembler code. Other nonstandard cases can be | |
539 | defined in the @code{PRINT_OPERAND} macro. You must also define | |
540 | which punctuation characters are valid with the | |
541 | @code{PRINT_OPERAND_PUNCT_VALID_P} macro. | |
542 | ||
543 | @cindex \ | |
544 | @cindex backslash | |
545 | The template may generate multiple assembler instructions. Write the text | |
546 | for the instructions, with @samp{\;} between them. | |
547 | ||
548 | @cindex matching operands | |
549 | When the RTL contains two operands which are required by constraint to match | |
550 | each other, the output template must refer only to the lower-numbered operand. | |
551 | Matching operands are not always identical, and the rest of the compiler | |
552 | arranges to put the proper RTL expression for printing into the lower-numbered | |
553 | operand. | |
554 | ||
555 | One use of nonstandard letters or punctuation following @samp{%} is to | |
556 | distinguish between different assembler languages for the same machine; for | |
557 | example, Motorola syntax versus MIT syntax for the 68000. Motorola syntax | |
558 | requires periods in most opcode names, while MIT syntax does not. For | |
559 | example, the opcode @samp{movel} in MIT syntax is @samp{move.l} in Motorola | |
560 | syntax. The same file of patterns is used for both kinds of output syntax, | |
561 | but the character sequence @samp{%.} is used in each place where Motorola | |
562 | syntax wants a period. The @code{PRINT_OPERAND} macro for Motorola syntax | |
563 | defines the sequence to output a period; the macro for MIT syntax defines | |
564 | it to do nothing. | |
565 | ||
566 | @cindex @code{#} in template | |
567 | As a special case, a template consisting of the single character @code{#} | |
568 | instructs the compiler to first split the insn, and then output the | |
569 | resulting instructions separately. This helps eliminate redundancy in the | |
570 | output templates. If you have a @code{define_insn} that needs to emit | |
e4ae5e77 | 571 | multiple assembler instructions, and there is a matching @code{define_split} |
03dda8e3 RK |
572 | already defined, then you can simply use @code{#} as the output template |
573 | instead of writing an output template that emits the multiple assembler | |
574 | instructions. | |
575 | ||
49e478af RS |
576 | Note that @code{#} only has an effect while generating assembly code; |
577 | it does not affect whether a split occurs earlier. An associated | |
578 | @code{define_split} must exist and it must be suitable for use after | |
579 | register allocation. | |
580 | ||
03dda8e3 RK |
581 | If the macro @code{ASSEMBLER_DIALECT} is defined, you can use construct |
582 | of the form @samp{@{option0|option1|option2@}} in the templates. These | |
583 | describe multiple variants of assembler language syntax. | |
584 | @xref{Instruction Output}. | |
585 | ||
586 | @node Output Statement | |
587 | @section C Statements for Assembler Output | |
588 | @cindex output statements | |
589 | @cindex C statements for assembler output | |
590 | @cindex generating assembler output | |
591 | ||
592 | Often a single fixed template string cannot produce correct and efficient | |
593 | assembler code for all the cases that are recognized by a single | |
594 | instruction pattern. For example, the opcodes may depend on the kinds of | |
595 | operands; or some unfortunate combinations of operands may require extra | |
596 | machine instructions. | |
597 | ||
598 | If the output control string starts with a @samp{@@}, then it is actually | |
599 | a series of templates, each on a separate line. (Blank lines and | |
600 | leading spaces and tabs are ignored.) The templates correspond to the | |
601 | pattern's constraint alternatives (@pxref{Multi-Alternative}). For example, | |
602 | if a target machine has a two-address add instruction @samp{addr} to add | |
603 | into a register and another @samp{addm} to add a register to memory, you | |
604 | might write this pattern: | |
605 | ||
606 | @smallexample | |
607 | (define_insn "addsi3" | |
608 | [(set (match_operand:SI 0 "general_operand" "=r,m") | |
609 | (plus:SI (match_operand:SI 1 "general_operand" "0,0") | |
610 | (match_operand:SI 2 "general_operand" "g,r")))] | |
611 | "" | |
612 | "@@ | |
613 | addr %2,%0 | |
614 | addm %2,%0") | |
615 | @end smallexample | |
616 | ||
617 | @cindex @code{*} in template | |
618 | @cindex asterisk in template | |
619 | If the output control string starts with a @samp{*}, then it is not an | |
620 | output template but rather a piece of C program that should compute a | |
621 | template. It should execute a @code{return} statement to return the | |
622 | template-string you want. Most such templates use C string literals, which | |
623 | require doublequote characters to delimit them. To include these | |
624 | doublequote characters in the string, prefix each one with @samp{\}. | |
625 | ||
0f40f9f7 ZW |
626 | If the output control string is written as a brace block instead of a |
627 | double-quoted string, it is automatically assumed to be C code. In that | |
628 | case, it is not necessary to put in a leading asterisk, or to escape the | |
629 | doublequotes surrounding C string literals. | |
630 | ||
03dda8e3 RK |
631 | The operands may be found in the array @code{operands}, whose C data type |
632 | is @code{rtx []}. | |
633 | ||
634 | It is very common to select different ways of generating assembler code | |
635 | based on whether an immediate operand is within a certain range. Be | |
636 | careful when doing this, because the result of @code{INTVAL} is an | |
637 | integer on the host machine. If the host machine has more bits in an | |
638 | @code{int} than the target machine has in the mode in which the constant | |
639 | will be used, then some of the bits you get from @code{INTVAL} will be | |
640 | superfluous. For proper results, you must carefully disregard the | |
641 | values of those bits. | |
642 | ||
643 | @findex output_asm_insn | |
644 | It is possible to output an assembler instruction and then go on to output | |
645 | or compute more of them, using the subroutine @code{output_asm_insn}. This | |
646 | receives two arguments: a template-string and a vector of operands. The | |
647 | vector may be @code{operands}, or it may be another array of @code{rtx} | |
648 | that you declare locally and initialize yourself. | |
649 | ||
650 | @findex which_alternative | |
651 | When an insn pattern has multiple alternatives in its constraints, often | |
652 | the appearance of the assembler code is determined mostly by which alternative | |
653 | was matched. When this is so, the C code can test the variable | |
654 | @code{which_alternative}, which is the ordinal number of the alternative | |
655 | that was actually satisfied (0 for the first, 1 for the second alternative, | |
656 | etc.). | |
657 | ||
658 | For example, suppose there are two opcodes for storing zero, @samp{clrreg} | |
659 | for registers and @samp{clrmem} for memory locations. Here is how | |
660 | a pattern could use @code{which_alternative} to choose between them: | |
661 | ||
662 | @smallexample | |
663 | (define_insn "" | |
664 | [(set (match_operand:SI 0 "general_operand" "=r,m") | |
665 | (const_int 0))] | |
666 | "" | |
0f40f9f7 | 667 | @{ |
03dda8e3 | 668 | return (which_alternative == 0 |
0f40f9f7 ZW |
669 | ? "clrreg %0" : "clrmem %0"); |
670 | @}) | |
03dda8e3 RK |
671 | @end smallexample |
672 | ||
673 | The example above, where the assembler code to generate was | |
674 | @emph{solely} determined by the alternative, could also have been specified | |
675 | as follows, having the output control string start with a @samp{@@}: | |
676 | ||
677 | @smallexample | |
678 | @group | |
679 | (define_insn "" | |
680 | [(set (match_operand:SI 0 "general_operand" "=r,m") | |
681 | (const_int 0))] | |
682 | "" | |
683 | "@@ | |
684 | clrreg %0 | |
685 | clrmem %0") | |
686 | @end group | |
687 | @end smallexample | |
e543e219 | 688 | |
94c765ab R |
689 | If you just need a little bit of C code in one (or a few) alternatives, |
690 | you can use @samp{*} inside of a @samp{@@} multi-alternative template: | |
691 | ||
692 | @smallexample | |
693 | @group | |
694 | (define_insn "" | |
695 | [(set (match_operand:SI 0 "general_operand" "=r,<,m") | |
696 | (const_int 0))] | |
697 | "" | |
698 | "@@ | |
699 | clrreg %0 | |
700 | * return stack_mem_p (operands[0]) ? \"push 0\" : \"clrmem %0\"; | |
701 | clrmem %0") | |
702 | @end group | |
703 | @end smallexample | |
704 | ||
e543e219 ZW |
705 | @node Predicates |
706 | @section Predicates | |
707 | @cindex predicates | |
708 | @cindex operand predicates | |
709 | @cindex operator predicates | |
710 | ||
711 | A predicate determines whether a @code{match_operand} or | |
712 | @code{match_operator} expression matches, and therefore whether the | |
713 | surrounding instruction pattern will be used for that combination of | |
714 | operands. GCC has a number of machine-independent predicates, and you | |
715 | can define machine-specific predicates as needed. By convention, | |
716 | predicates used with @code{match_operand} have names that end in | |
717 | @samp{_operand}, and those used with @code{match_operator} have names | |
718 | that end in @samp{_operator}. | |
719 | ||
527a3750 | 720 | All predicates are boolean functions (in the mathematical sense) of |
e543e219 ZW |
721 | two arguments: the RTL expression that is being considered at that |
722 | position in the instruction pattern, and the machine mode that the | |
723 | @code{match_operand} or @code{match_operator} specifies. In this | |
724 | section, the first argument is called @var{op} and the second argument | |
725 | @var{mode}. Predicates can be called from C as ordinary two-argument | |
726 | functions; this can be useful in output templates or other | |
727 | machine-specific code. | |
728 | ||
729 | Operand predicates can allow operands that are not actually acceptable | |
730 | to the hardware, as long as the constraints give reload the ability to | |
731 | fix them up (@pxref{Constraints}). However, GCC will usually generate | |
732 | better code if the predicates specify the requirements of the machine | |
733 | instructions as closely as possible. Reload cannot fix up operands | |
734 | that must be constants (``immediate operands''); you must use a | |
735 | predicate that allows only constants, or else enforce the requirement | |
736 | in the extra condition. | |
737 | ||
738 | @cindex predicates and machine modes | |
739 | @cindex normal predicates | |
740 | @cindex special predicates | |
741 | Most predicates handle their @var{mode} argument in a uniform manner. | |
742 | If @var{mode} is @code{VOIDmode} (unspecified), then @var{op} can have | |
743 | any mode. If @var{mode} is anything else, then @var{op} must have the | |
744 | same mode, unless @var{op} is a @code{CONST_INT} or integer | |
745 | @code{CONST_DOUBLE}. These RTL expressions always have | |
746 | @code{VOIDmode}, so it would be counterproductive to check that their | |
747 | mode matches. Instead, predicates that accept @code{CONST_INT} and/or | |
748 | integer @code{CONST_DOUBLE} check that the value stored in the | |
749 | constant will fit in the requested mode. | |
750 | ||
751 | Predicates with this behavior are called @dfn{normal}. | |
752 | @command{genrecog} can optimize the instruction recognizer based on | |
753 | knowledge of how normal predicates treat modes. It can also diagnose | |
754 | certain kinds of common errors in the use of normal predicates; for | |
755 | instance, it is almost always an error to use a normal predicate | |
756 | without specifying a mode. | |
757 | ||
758 | Predicates that do something different with their @var{mode} argument | |
759 | are called @dfn{special}. The generic predicates | |
760 | @code{address_operand} and @code{pmode_register_operand} are special | |
761 | predicates. @command{genrecog} does not do any optimizations or | |
762 | diagnosis when special predicates are used. | |
763 | ||
764 | @menu | |
765 | * Machine-Independent Predicates:: Predicates available to all back ends. | |
766 | * Defining Predicates:: How to write machine-specific predicate | |
767 | functions. | |
768 | @end menu | |
769 | ||
770 | @node Machine-Independent Predicates | |
771 | @subsection Machine-Independent Predicates | |
772 | @cindex machine-independent predicates | |
773 | @cindex generic predicates | |
774 | ||
775 | These are the generic predicates available to all back ends. They are | |
776 | defined in @file{recog.c}. The first category of predicates allow | |
777 | only constant, or @dfn{immediate}, operands. | |
778 | ||
779 | @defun immediate_operand | |
780 | This predicate allows any sort of constant that fits in @var{mode}. | |
781 | It is an appropriate choice for instructions that take operands that | |
782 | must be constant. | |
783 | @end defun | |
784 | ||
785 | @defun const_int_operand | |
786 | This predicate allows any @code{CONST_INT} expression that fits in | |
787 | @var{mode}. It is an appropriate choice for an immediate operand that | |
788 | does not allow a symbol or label. | |
789 | @end defun | |
790 | ||
791 | @defun const_double_operand | |
792 | This predicate accepts any @code{CONST_DOUBLE} expression that has | |
793 | exactly @var{mode}. If @var{mode} is @code{VOIDmode}, it will also | |
794 | accept @code{CONST_INT}. It is intended for immediate floating point | |
795 | constants. | |
796 | @end defun | |
797 | ||
798 | @noindent | |
799 | The second category of predicates allow only some kind of machine | |
800 | register. | |
801 | ||
802 | @defun register_operand | |
803 | This predicate allows any @code{REG} or @code{SUBREG} expression that | |
804 | is valid for @var{mode}. It is often suitable for arithmetic | |
805 | instruction operands on a RISC machine. | |
806 | @end defun | |
807 | ||
808 | @defun pmode_register_operand | |
809 | This is a slight variant on @code{register_operand} which works around | |
810 | a limitation in the machine-description reader. | |
811 | ||
cd1a8088 | 812 | @smallexample |
e543e219 | 813 | (match_operand @var{n} "pmode_register_operand" @var{constraint}) |
cd1a8088 | 814 | @end smallexample |
e543e219 ZW |
815 | |
816 | @noindent | |
817 | means exactly what | |
818 | ||
cd1a8088 | 819 | @smallexample |
e543e219 | 820 | (match_operand:P @var{n} "register_operand" @var{constraint}) |
cd1a8088 | 821 | @end smallexample |
e543e219 ZW |
822 | |
823 | @noindent | |
824 | would mean, if the machine-description reader accepted @samp{:P} | |
825 | mode suffixes. Unfortunately, it cannot, because @code{Pmode} is an | |
826 | alias for some other mode, and might vary with machine-specific | |
8a36672b | 827 | options. @xref{Misc}. |
e543e219 ZW |
828 | @end defun |
829 | ||
830 | @defun scratch_operand | |
831 | This predicate allows hard registers and @code{SCRATCH} expressions, | |
832 | but not pseudo-registers. It is used internally by @code{match_scratch}; | |
833 | it should not be used directly. | |
834 | @end defun | |
835 | ||
836 | @noindent | |
837 | The third category of predicates allow only some kind of memory reference. | |
838 | ||
839 | @defun memory_operand | |
840 | This predicate allows any valid reference to a quantity of mode | |
841 | @var{mode} in memory, as determined by the weak form of | |
842 | @code{GO_IF_LEGITIMATE_ADDRESS} (@pxref{Addressing Modes}). | |
843 | @end defun | |
844 | ||
845 | @defun address_operand | |
846 | This predicate is a little unusual; it allows any operand that is a | |
847 | valid expression for the @emph{address} of a quantity of mode | |
848 | @var{mode}, again determined by the weak form of | |
849 | @code{GO_IF_LEGITIMATE_ADDRESS}. To first order, if | |
850 | @samp{@w{(mem:@var{mode} (@var{exp}))}} is acceptable to | |
851 | @code{memory_operand}, then @var{exp} is acceptable to | |
852 | @code{address_operand}. Note that @var{exp} does not necessarily have | |
853 | the mode @var{mode}. | |
854 | @end defun | |
855 | ||
856 | @defun indirect_operand | |
857 | This is a stricter form of @code{memory_operand} which allows only | |
858 | memory references with a @code{general_operand} as the address | |
859 | expression. New uses of this predicate are discouraged, because | |
860 | @code{general_operand} is very permissive, so it's hard to tell what | |
861 | an @code{indirect_operand} does or does not allow. If a target has | |
862 | different requirements for memory operands for different instructions, | |
863 | it is better to define target-specific predicates which enforce the | |
864 | hardware's requirements explicitly. | |
865 | @end defun | |
866 | ||
867 | @defun push_operand | |
868 | This predicate allows a memory reference suitable for pushing a value | |
869 | onto the stack. This will be a @code{MEM} which refers to | |
870 | @code{stack_pointer_rtx}, with a side-effect in its address expression | |
871 | (@pxref{Incdec}); which one is determined by the | |
872 | @code{STACK_PUSH_CODE} macro (@pxref{Frame Layout}). | |
873 | @end defun | |
874 | ||
875 | @defun pop_operand | |
876 | This predicate allows a memory reference suitable for popping a value | |
877 | off the stack. Again, this will be a @code{MEM} referring to | |
878 | @code{stack_pointer_rtx}, with a side-effect in its address | |
879 | expression. However, this time @code{STACK_POP_CODE} is expected. | |
880 | @end defun | |
881 | ||
882 | @noindent | |
883 | The fourth category of predicates allow some combination of the above | |
884 | operands. | |
885 | ||
886 | @defun nonmemory_operand | |
887 | This predicate allows any immediate or register operand valid for @var{mode}. | |
888 | @end defun | |
889 | ||
890 | @defun nonimmediate_operand | |
891 | This predicate allows any register or memory operand valid for @var{mode}. | |
892 | @end defun | |
893 | ||
894 | @defun general_operand | |
895 | This predicate allows any immediate, register, or memory operand | |
896 | valid for @var{mode}. | |
897 | @end defun | |
898 | ||
899 | @noindent | |
c6963675 | 900 | Finally, there are two generic operator predicates. |
e543e219 ZW |
901 | |
902 | @defun comparison_operator | |
903 | This predicate matches any expression which performs an arithmetic | |
904 | comparison in @var{mode}; that is, @code{COMPARISON_P} is true for the | |
905 | expression code. | |
906 | @end defun | |
907 | ||
c6963675 PB |
908 | @defun ordered_comparison_operator |
909 | This predicate matches any expression which performs an arithmetic | |
910 | comparison in @var{mode} and whose expression code is valid for integer | |
911 | modes; that is, the expression code will be one of @code{eq}, @code{ne}, | |
912 | @code{lt}, @code{ltu}, @code{le}, @code{leu}, @code{gt}, @code{gtu}, | |
913 | @code{ge}, @code{geu}. | |
914 | @end defun | |
915 | ||
e543e219 ZW |
916 | @node Defining Predicates |
917 | @subsection Defining Machine-Specific Predicates | |
918 | @cindex defining predicates | |
919 | @findex define_predicate | |
920 | @findex define_special_predicate | |
921 | ||
922 | Many machines have requirements for their operands that cannot be | |
923 | expressed precisely using the generic predicates. You can define | |
924 | additional predicates using @code{define_predicate} and | |
925 | @code{define_special_predicate} expressions. These expressions have | |
926 | three operands: | |
927 | ||
928 | @itemize @bullet | |
929 | @item | |
930 | The name of the predicate, as it will be referred to in | |
931 | @code{match_operand} or @code{match_operator} expressions. | |
932 | ||
933 | @item | |
934 | An RTL expression which evaluates to true if the predicate allows the | |
935 | operand @var{op}, false if it does not. This expression can only use | |
936 | the following RTL codes: | |
937 | ||
938 | @table @code | |
939 | @item MATCH_OPERAND | |
940 | When written inside a predicate expression, a @code{MATCH_OPERAND} | |
941 | expression evaluates to true if the predicate it names would allow | |
942 | @var{op}. The operand number and constraint are ignored. Due to | |
943 | limitations in @command{genrecog}, you can only refer to generic | |
944 | predicates and predicates that have already been defined. | |
945 | ||
946 | @item MATCH_CODE | |
6e7a4706 ZW |
947 | This expression evaluates to true if @var{op} or a specified |
948 | subexpression of @var{op} has one of a given list of RTX codes. | |
949 | ||
950 | The first operand of this expression is a string constant containing a | |
951 | comma-separated list of RTX code names (in lower case). These are the | |
952 | codes for which the @code{MATCH_CODE} will be true. | |
953 | ||
954 | The second operand is a string constant which indicates what | |
955 | subexpression of @var{op} to examine. If it is absent or the empty | |
956 | string, @var{op} itself is examined. Otherwise, the string constant | |
957 | must be a sequence of digits and/or lowercase letters. Each character | |
958 | indicates a subexpression to extract from the current expression; for | |
959 | the first character this is @var{op}, for the second and subsequent | |
960 | characters it is the result of the previous character. A digit | |
961 | @var{n} extracts @samp{@w{XEXP (@var{e}, @var{n})}}; a letter @var{l} | |
962 | extracts @samp{@w{XVECEXP (@var{e}, 0, @var{n})}} where @var{n} is the | |
963 | alphabetic ordinal of @var{l} (0 for `a', 1 for 'b', and so on). The | |
964 | @code{MATCH_CODE} then examines the RTX code of the subexpression | |
965 | extracted by the complete string. It is not possible to extract | |
966 | components of an @code{rtvec} that is not at position 0 within its RTX | |
967 | object. | |
e543e219 ZW |
968 | |
969 | @item MATCH_TEST | |
970 | This expression has one operand, a string constant containing a C | |
971 | expression. The predicate's arguments, @var{op} and @var{mode}, are | |
972 | available with those names in the C expression. The @code{MATCH_TEST} | |
973 | evaluates to true if the C expression evaluates to a nonzero value. | |
974 | @code{MATCH_TEST} expressions must not have side effects. | |
975 | ||
976 | @item AND | |
977 | @itemx IOR | |
978 | @itemx NOT | |
979 | @itemx IF_THEN_ELSE | |
980 | The basic @samp{MATCH_} expressions can be combined using these | |
981 | logical operators, which have the semantics of the C operators | |
6e7a4706 ZW |
982 | @samp{&&}, @samp{||}, @samp{!}, and @samp{@w{? :}} respectively. As |
983 | in Common Lisp, you may give an @code{AND} or @code{IOR} expression an | |
984 | arbitrary number of arguments; this has exactly the same effect as | |
985 | writing a chain of two-argument @code{AND} or @code{IOR} expressions. | |
e543e219 ZW |
986 | @end table |
987 | ||
988 | @item | |
f0eb93a8 | 989 | An optional block of C code, which should execute |
e543e219 ZW |
990 | @samp{@w{return true}} if the predicate is found to match and |
991 | @samp{@w{return false}} if it does not. It must not have any side | |
992 | effects. The predicate arguments, @var{op} and @var{mode}, are | |
993 | available with those names. | |
994 | ||
995 | If a code block is present in a predicate definition, then the RTL | |
996 | expression must evaluate to true @emph{and} the code block must | |
997 | execute @samp{@w{return true}} for the predicate to allow the operand. | |
998 | The RTL expression is evaluated first; do not re-check anything in the | |
999 | code block that was checked in the RTL expression. | |
1000 | @end itemize | |
1001 | ||
1002 | The program @command{genrecog} scans @code{define_predicate} and | |
1003 | @code{define_special_predicate} expressions to determine which RTX | |
1004 | codes are possibly allowed. You should always make this explicit in | |
1005 | the RTL predicate expression, using @code{MATCH_OPERAND} and | |
1006 | @code{MATCH_CODE}. | |
1007 | ||
1008 | Here is an example of a simple predicate definition, from the IA64 | |
1009 | machine description: | |
1010 | ||
1011 | @smallexample | |
1012 | @group | |
1013 | ;; @r{True if @var{op} is a @code{SYMBOL_REF} which refers to the sdata section.} | |
1014 | (define_predicate "small_addr_symbolic_operand" | |
1015 | (and (match_code "symbol_ref") | |
1016 | (match_test "SYMBOL_REF_SMALL_ADDR_P (op)"))) | |
1017 | @end group | |
1018 | @end smallexample | |
1019 | ||
1020 | @noindent | |
1021 | And here is another, showing the use of the C block. | |
1022 | ||
1023 | @smallexample | |
1024 | @group | |
1025 | ;; @r{True if @var{op} is a register operand that is (or could be) a GR reg.} | |
1026 | (define_predicate "gr_register_operand" | |
1027 | (match_operand 0 "register_operand") | |
1028 | @{ | |
1029 | unsigned int regno; | |
1030 | if (GET_CODE (op) == SUBREG) | |
1031 | op = SUBREG_REG (op); | |
1032 | ||
1033 | regno = REGNO (op); | |
1034 | return (regno >= FIRST_PSEUDO_REGISTER || GENERAL_REGNO_P (regno)); | |
1035 | @}) | |
1036 | @end group | |
1037 | @end smallexample | |
1038 | ||
1039 | Predicates written with @code{define_predicate} automatically include | |
1040 | a test that @var{mode} is @code{VOIDmode}, or @var{op} has the same | |
1041 | mode as @var{mode}, or @var{op} is a @code{CONST_INT} or | |
1042 | @code{CONST_DOUBLE}. They do @emph{not} check specifically for | |
1043 | integer @code{CONST_DOUBLE}, nor do they test that the value of either | |
1044 | kind of constant fits in the requested mode. This is because | |
1045 | target-specific predicates that take constants usually have to do more | |
1046 | stringent value checks anyway. If you need the exact same treatment | |
1047 | of @code{CONST_INT} or @code{CONST_DOUBLE} that the generic predicates | |
1048 | provide, use a @code{MATCH_OPERAND} subexpression to call | |
1049 | @code{const_int_operand}, @code{const_double_operand}, or | |
1050 | @code{immediate_operand}. | |
1051 | ||
1052 | Predicates written with @code{define_special_predicate} do not get any | |
1053 | automatic mode checks, and are treated as having special mode handling | |
1054 | by @command{genrecog}. | |
1055 | ||
1056 | The program @command{genpreds} is responsible for generating code to | |
1057 | test predicates. It also writes a header file containing function | |
1058 | declarations for all machine-specific predicates. It is not necessary | |
1059 | to declare these predicates in @file{@var{cpu}-protos.h}. | |
03dda8e3 RK |
1060 | @end ifset |
1061 | ||
1062 | @c Most of this node appears by itself (in a different place) even | |
b11cc610 JM |
1063 | @c when the INTERNALS flag is clear. Passages that require the internals |
1064 | @c manual's context are conditionalized to appear only in the internals manual. | |
03dda8e3 RK |
1065 | @ifset INTERNALS |
1066 | @node Constraints | |
1067 | @section Operand Constraints | |
1068 | @cindex operand constraints | |
1069 | @cindex constraints | |
1070 | ||
e543e219 ZW |
1071 | Each @code{match_operand} in an instruction pattern can specify |
1072 | constraints for the operands allowed. The constraints allow you to | |
1073 | fine-tune matching within the set of operands allowed by the | |
1074 | predicate. | |
1075 | ||
03dda8e3 RK |
1076 | @end ifset |
1077 | @ifclear INTERNALS | |
1078 | @node Constraints | |
1079 | @section Constraints for @code{asm} Operands | |
1080 | @cindex operand constraints, @code{asm} | |
1081 | @cindex constraints, @code{asm} | |
1082 | @cindex @code{asm} constraints | |
1083 | ||
1084 | Here are specific details on what constraint letters you can use with | |
1085 | @code{asm} operands. | |
1086 | @end ifclear | |
1087 | Constraints can say whether | |
1088 | an operand may be in a register, and which kinds of register; whether the | |
1089 | operand can be a memory reference, and which kinds of address; whether the | |
1090 | operand may be an immediate constant, and which possible values it may | |
1091 | have. Constraints can also require two operands to match. | |
54f044eb JJ |
1092 | Side-effects aren't allowed in operands of inline @code{asm}, unless |
1093 | @samp{<} or @samp{>} constraints are used, because there is no guarantee | |
1094 | that the side-effects will happen exactly once in an instruction that can update | |
1095 | the addressing register. | |
03dda8e3 RK |
1096 | |
1097 | @ifset INTERNALS | |
1098 | @menu | |
1099 | * Simple Constraints:: Basic use of constraints. | |
1100 | * Multi-Alternative:: When an insn has two alternative constraint-patterns. | |
1101 | * Class Preferences:: Constraints guide which hard register to put things in. | |
1102 | * Modifiers:: More precise control over effects of constraints. | |
1103 | * Machine Constraints:: Existing constraints for some particular machines. | |
9840b2fa | 1104 | * Disable Insn Alternatives:: Disable insn alternatives using attributes. |
f38840db ZW |
1105 | * Define Constraints:: How to define machine-specific constraints. |
1106 | * C Constraint Interface:: How to test constraints from C code. | |
03dda8e3 RK |
1107 | @end menu |
1108 | @end ifset | |
1109 | ||
1110 | @ifclear INTERNALS | |
1111 | @menu | |
1112 | * Simple Constraints:: Basic use of constraints. | |
1113 | * Multi-Alternative:: When an insn has two alternative constraint-patterns. | |
1114 | * Modifiers:: More precise control over effects of constraints. | |
1115 | * Machine Constraints:: Special constraints for some particular machines. | |
1116 | @end menu | |
1117 | @end ifclear | |
1118 | ||
1119 | @node Simple Constraints | |
1120 | @subsection Simple Constraints | |
1121 | @cindex simple constraints | |
1122 | ||
1123 | The simplest kind of constraint is a string full of letters, each of | |
1124 | which describes one kind of operand that is permitted. Here are | |
1125 | the letters that are allowed: | |
1126 | ||
1127 | @table @asis | |
88a56c2e HPN |
1128 | @item whitespace |
1129 | Whitespace characters are ignored and can be inserted at any position | |
1130 | except the first. This enables each alternative for different operands to | |
1131 | be visually aligned in the machine description even if they have different | |
1132 | number of constraints and modifiers. | |
1133 | ||
03dda8e3 RK |
1134 | @cindex @samp{m} in constraint |
1135 | @cindex memory references in constraints | |
1136 | @item @samp{m} | |
1137 | A memory operand is allowed, with any kind of address that the machine | |
1138 | supports in general. | |
a4edaf83 AK |
1139 | Note that the letter used for the general memory constraint can be |
1140 | re-defined by a back end using the @code{TARGET_MEM_CONSTRAINT} macro. | |
03dda8e3 RK |
1141 | |
1142 | @cindex offsettable address | |
1143 | @cindex @samp{o} in constraint | |
1144 | @item @samp{o} | |
1145 | A memory operand is allowed, but only if the address is | |
1146 | @dfn{offsettable}. This means that adding a small integer (actually, | |
1147 | the width in bytes of the operand, as determined by its machine mode) | |
1148 | may be added to the address and the result is also a valid memory | |
1149 | address. | |
1150 | ||
1151 | @cindex autoincrement/decrement addressing | |
1152 | For example, an address which is constant is offsettable; so is an | |
1153 | address that is the sum of a register and a constant (as long as a | |
1154 | slightly larger constant is also within the range of address-offsets | |
1155 | supported by the machine); but an autoincrement or autodecrement | |
1156 | address is not offsettable. More complicated indirect/indexed | |
1157 | addresses may or may not be offsettable depending on the other | |
1158 | addressing modes that the machine supports. | |
1159 | ||
1160 | Note that in an output operand which can be matched by another | |
1161 | operand, the constraint letter @samp{o} is valid only when accompanied | |
1162 | by both @samp{<} (if the target machine has predecrement addressing) | |
1163 | and @samp{>} (if the target machine has preincrement addressing). | |
1164 | ||
1165 | @cindex @samp{V} in constraint | |
1166 | @item @samp{V} | |
1167 | A memory operand that is not offsettable. In other words, anything that | |
1168 | would fit the @samp{m} constraint but not the @samp{o} constraint. | |
1169 | ||
1170 | @cindex @samp{<} in constraint | |
1171 | @item @samp{<} | |
1172 | A memory operand with autodecrement addressing (either predecrement or | |
54f044eb JJ |
1173 | postdecrement) is allowed. In inline @code{asm} this constraint is only |
1174 | allowed if the operand is used exactly once in an instruction that can | |
1175 | handle the side-effects. Not using an operand with @samp{<} in constraint | |
1176 | string in the inline @code{asm} pattern at all or using it in multiple | |
1177 | instructions isn't valid, because the side-effects wouldn't be performed | |
1178 | or would be performed more than once. Furthermore, on some targets | |
1179 | the operand with @samp{<} in constraint string must be accompanied by | |
1180 | special instruction suffixes like @code{%U0} instruction suffix on PowerPC | |
1181 | or @code{%P0} on IA-64. | |
03dda8e3 RK |
1182 | |
1183 | @cindex @samp{>} in constraint | |
1184 | @item @samp{>} | |
1185 | A memory operand with autoincrement addressing (either preincrement or | |
54f044eb JJ |
1186 | postincrement) is allowed. In inline @code{asm} the same restrictions |
1187 | as for @samp{<} apply. | |
03dda8e3 RK |
1188 | |
1189 | @cindex @samp{r} in constraint | |
1190 | @cindex registers in constraints | |
1191 | @item @samp{r} | |
1192 | A register operand is allowed provided that it is in a general | |
1193 | register. | |
1194 | ||
03dda8e3 RK |
1195 | @cindex constants in constraints |
1196 | @cindex @samp{i} in constraint | |
1197 | @item @samp{i} | |
1198 | An immediate integer operand (one with constant value) is allowed. | |
1199 | This includes symbolic constants whose values will be known only at | |
8ac658b6 | 1200 | assembly time or later. |
03dda8e3 RK |
1201 | |
1202 | @cindex @samp{n} in constraint | |
1203 | @item @samp{n} | |
1204 | An immediate integer operand with a known numeric value is allowed. | |
1205 | Many systems cannot support assembly-time constants for operands less | |
1206 | than a word wide. Constraints for these operands should use @samp{n} | |
1207 | rather than @samp{i}. | |
1208 | ||
1209 | @cindex @samp{I} in constraint | |
1210 | @item @samp{I}, @samp{J}, @samp{K}, @dots{} @samp{P} | |
1211 | Other letters in the range @samp{I} through @samp{P} may be defined in | |
1212 | a machine-dependent fashion to permit immediate integer operands with | |
1213 | explicit integer values in specified ranges. For example, on the | |
1214 | 68000, @samp{I} is defined to stand for the range of values 1 to 8. | |
1215 | This is the range permitted as a shift count in the shift | |
1216 | instructions. | |
1217 | ||
1218 | @cindex @samp{E} in constraint | |
1219 | @item @samp{E} | |
1220 | An immediate floating operand (expression code @code{const_double}) is | |
1221 | allowed, but only if the target floating point format is the same as | |
1222 | that of the host machine (on which the compiler is running). | |
1223 | ||
1224 | @cindex @samp{F} in constraint | |
1225 | @item @samp{F} | |
bf7cd754 R |
1226 | An immediate floating operand (expression code @code{const_double} or |
1227 | @code{const_vector}) is allowed. | |
03dda8e3 RK |
1228 | |
1229 | @cindex @samp{G} in constraint | |
1230 | @cindex @samp{H} in constraint | |
1231 | @item @samp{G}, @samp{H} | |
1232 | @samp{G} and @samp{H} may be defined in a machine-dependent fashion to | |
1233 | permit immediate floating operands in particular ranges of values. | |
1234 | ||
1235 | @cindex @samp{s} in constraint | |
1236 | @item @samp{s} | |
1237 | An immediate integer operand whose value is not an explicit integer is | |
1238 | allowed. | |
1239 | ||
1240 | This might appear strange; if an insn allows a constant operand with a | |
1241 | value not known at compile time, it certainly must allow any known | |
1242 | value. So why use @samp{s} instead of @samp{i}? Sometimes it allows | |
1243 | better code to be generated. | |
1244 | ||
1245 | For example, on the 68000 in a fullword instruction it is possible to | |
630d3d5a | 1246 | use an immediate operand; but if the immediate value is between @minus{}128 |
03dda8e3 RK |
1247 | and 127, better code results from loading the value into a register and |
1248 | using the register. This is because the load into the register can be | |
1249 | done with a @samp{moveq} instruction. We arrange for this to happen | |
1250 | by defining the letter @samp{K} to mean ``any integer outside the | |
630d3d5a | 1251 | range @minus{}128 to 127'', and then specifying @samp{Ks} in the operand |
03dda8e3 RK |
1252 | constraints. |
1253 | ||
1254 | @cindex @samp{g} in constraint | |
1255 | @item @samp{g} | |
1256 | Any register, memory or immediate integer operand is allowed, except for | |
1257 | registers that are not general registers. | |
1258 | ||
1259 | @cindex @samp{X} in constraint | |
1260 | @item @samp{X} | |
1261 | @ifset INTERNALS | |
1262 | Any operand whatsoever is allowed, even if it does not satisfy | |
1263 | @code{general_operand}. This is normally used in the constraint of | |
1264 | a @code{match_scratch} when certain alternatives will not actually | |
1265 | require a scratch register. | |
1266 | @end ifset | |
1267 | @ifclear INTERNALS | |
1268 | Any operand whatsoever is allowed. | |
1269 | @end ifclear | |
1270 | ||
1271 | @cindex @samp{0} in constraint | |
1272 | @cindex digits in constraint | |
1273 | @item @samp{0}, @samp{1}, @samp{2}, @dots{} @samp{9} | |
1274 | An operand that matches the specified operand number is allowed. If a | |
1275 | digit is used together with letters within the same alternative, the | |
1276 | digit should come last. | |
1277 | ||
84b72302 | 1278 | This number is allowed to be more than a single digit. If multiple |
c0478a66 | 1279 | digits are encountered consecutively, they are interpreted as a single |
84b72302 RH |
1280 | decimal integer. There is scant chance for ambiguity, since to-date |
1281 | it has never been desirable that @samp{10} be interpreted as matching | |
1282 | either operand 1 @emph{or} operand 0. Should this be desired, one | |
1283 | can use multiple alternatives instead. | |
1284 | ||
03dda8e3 RK |
1285 | @cindex matching constraint |
1286 | @cindex constraint, matching | |
1287 | This is called a @dfn{matching constraint} and what it really means is | |
1288 | that the assembler has only a single operand that fills two roles | |
1289 | @ifset INTERNALS | |
1290 | considered separate in the RTL insn. For example, an add insn has two | |
1291 | input operands and one output operand in the RTL, but on most CISC | |
1292 | @end ifset | |
1293 | @ifclear INTERNALS | |
1294 | which @code{asm} distinguishes. For example, an add instruction uses | |
1295 | two input operands and an output operand, but on most CISC | |
1296 | @end ifclear | |
1297 | machines an add instruction really has only two operands, one of them an | |
1298 | input-output operand: | |
1299 | ||
1300 | @smallexample | |
1301 | addl #35,r12 | |
1302 | @end smallexample | |
1303 | ||
1304 | Matching constraints are used in these circumstances. | |
1305 | More precisely, the two operands that match must include one input-only | |
1306 | operand and one output-only operand. Moreover, the digit must be a | |
1307 | smaller number than the number of the operand that uses it in the | |
1308 | constraint. | |
1309 | ||
1310 | @ifset INTERNALS | |
1311 | For operands to match in a particular case usually means that they | |
1312 | are identical-looking RTL expressions. But in a few special cases | |
1313 | specific kinds of dissimilarity are allowed. For example, @code{*x} | |
1314 | as an input operand will match @code{*x++} as an output operand. | |
1315 | For proper results in such cases, the output template should always | |
1316 | use the output-operand's number when printing the operand. | |
1317 | @end ifset | |
1318 | ||
1319 | @cindex load address instruction | |
1320 | @cindex push address instruction | |
1321 | @cindex address constraints | |
1322 | @cindex @samp{p} in constraint | |
1323 | @item @samp{p} | |
1324 | An operand that is a valid memory address is allowed. This is | |
1325 | for ``load address'' and ``push address'' instructions. | |
1326 | ||
1327 | @findex address_operand | |
1328 | @samp{p} in the constraint must be accompanied by @code{address_operand} | |
1329 | as the predicate in the @code{match_operand}. This predicate interprets | |
1330 | the mode specified in the @code{match_operand} as the mode of the memory | |
1331 | reference for which the address would be valid. | |
1332 | ||
c2cba7a9 | 1333 | @cindex other register constraints |
03dda8e3 | 1334 | @cindex extensible constraints |
630d3d5a | 1335 | @item @var{other-letters} |
c2cba7a9 RH |
1336 | Other letters can be defined in machine-dependent fashion to stand for |
1337 | particular classes of registers or other arbitrary operand types. | |
1338 | @samp{d}, @samp{a} and @samp{f} are defined on the 68000/68020 to stand | |
1339 | for data, address and floating point registers. | |
03dda8e3 RK |
1340 | @end table |
1341 | ||
1342 | @ifset INTERNALS | |
1343 | In order to have valid assembler code, each operand must satisfy | |
1344 | its constraint. But a failure to do so does not prevent the pattern | |
1345 | from applying to an insn. Instead, it directs the compiler to modify | |
1346 | the code so that the constraint will be satisfied. Usually this is | |
1347 | done by copying an operand into a register. | |
1348 | ||
1349 | Contrast, therefore, the two instruction patterns that follow: | |
1350 | ||
1351 | @smallexample | |
1352 | (define_insn "" | |
1353 | [(set (match_operand:SI 0 "general_operand" "=r") | |
1354 | (plus:SI (match_dup 0) | |
1355 | (match_operand:SI 1 "general_operand" "r")))] | |
1356 | "" | |
1357 | "@dots{}") | |
1358 | @end smallexample | |
1359 | ||
1360 | @noindent | |
1361 | which has two operands, one of which must appear in two places, and | |
1362 | ||
1363 | @smallexample | |
1364 | (define_insn "" | |
1365 | [(set (match_operand:SI 0 "general_operand" "=r") | |
1366 | (plus:SI (match_operand:SI 1 "general_operand" "0") | |
1367 | (match_operand:SI 2 "general_operand" "r")))] | |
1368 | "" | |
1369 | "@dots{}") | |
1370 | @end smallexample | |
1371 | ||
1372 | @noindent | |
1373 | which has three operands, two of which are required by a constraint to be | |
1374 | identical. If we are considering an insn of the form | |
1375 | ||
1376 | @smallexample | |
1377 | (insn @var{n} @var{prev} @var{next} | |
1378 | (set (reg:SI 3) | |
1379 | (plus:SI (reg:SI 6) (reg:SI 109))) | |
1380 | @dots{}) | |
1381 | @end smallexample | |
1382 | ||
1383 | @noindent | |
1384 | the first pattern would not apply at all, because this insn does not | |
1385 | contain two identical subexpressions in the right place. The pattern would | |
d78aa55c | 1386 | say, ``That does not look like an add instruction; try other patterns''. |
03dda8e3 | 1387 | The second pattern would say, ``Yes, that's an add instruction, but there |
d78aa55c | 1388 | is something wrong with it''. It would direct the reload pass of the |
03dda8e3 RK |
1389 | compiler to generate additional insns to make the constraint true. The |
1390 | results might look like this: | |
1391 | ||
1392 | @smallexample | |
1393 | (insn @var{n2} @var{prev} @var{n} | |
1394 | (set (reg:SI 3) (reg:SI 6)) | |
1395 | @dots{}) | |
1396 | ||
1397 | (insn @var{n} @var{n2} @var{next} | |
1398 | (set (reg:SI 3) | |
1399 | (plus:SI (reg:SI 3) (reg:SI 109))) | |
1400 | @dots{}) | |
1401 | @end smallexample | |
1402 | ||
1403 | It is up to you to make sure that each operand, in each pattern, has | |
1404 | constraints that can handle any RTL expression that could be present for | |
1405 | that operand. (When multiple alternatives are in use, each pattern must, | |
1406 | for each possible combination of operand expressions, have at least one | |
1407 | alternative which can handle that combination of operands.) The | |
1408 | constraints don't need to @emph{allow} any possible operand---when this is | |
1409 | the case, they do not constrain---but they must at least point the way to | |
1410 | reloading any possible operand so that it will fit. | |
1411 | ||
1412 | @itemize @bullet | |
1413 | @item | |
1414 | If the constraint accepts whatever operands the predicate permits, | |
1415 | there is no problem: reloading is never necessary for this operand. | |
1416 | ||
1417 | For example, an operand whose constraints permit everything except | |
1418 | registers is safe provided its predicate rejects registers. | |
1419 | ||
1420 | An operand whose predicate accepts only constant values is safe | |
1421 | provided its constraints include the letter @samp{i}. If any possible | |
1422 | constant value is accepted, then nothing less than @samp{i} will do; | |
1423 | if the predicate is more selective, then the constraints may also be | |
1424 | more selective. | |
1425 | ||
1426 | @item | |
1427 | Any operand expression can be reloaded by copying it into a register. | |
1428 | So if an operand's constraints allow some kind of register, it is | |
1429 | certain to be safe. It need not permit all classes of registers; the | |
1430 | compiler knows how to copy a register into another register of the | |
1431 | proper class in order to make an instruction valid. | |
1432 | ||
1433 | @cindex nonoffsettable memory reference | |
1434 | @cindex memory reference, nonoffsettable | |
1435 | @item | |
1436 | A nonoffsettable memory reference can be reloaded by copying the | |
1437 | address into a register. So if the constraint uses the letter | |
1438 | @samp{o}, all memory references are taken care of. | |
1439 | ||
1440 | @item | |
1441 | A constant operand can be reloaded by allocating space in memory to | |
1442 | hold it as preinitialized data. Then the memory reference can be used | |
1443 | in place of the constant. So if the constraint uses the letters | |
1444 | @samp{o} or @samp{m}, constant operands are not a problem. | |
1445 | ||
1446 | @item | |
1447 | If the constraint permits a constant and a pseudo register used in an insn | |
1448 | was not allocated to a hard register and is equivalent to a constant, | |
1449 | the register will be replaced with the constant. If the predicate does | |
1450 | not permit a constant and the insn is re-recognized for some reason, the | |
1451 | compiler will crash. Thus the predicate must always recognize any | |
1452 | objects allowed by the constraint. | |
1453 | @end itemize | |
1454 | ||
1455 | If the operand's predicate can recognize registers, but the constraint does | |
1456 | not permit them, it can make the compiler crash. When this operand happens | |
1457 | to be a register, the reload pass will be stymied, because it does not know | |
1458 | how to copy a register temporarily into memory. | |
1459 | ||
1460 | If the predicate accepts a unary operator, the constraint applies to the | |
1461 | operand. For example, the MIPS processor at ISA level 3 supports an | |
1462 | instruction which adds two registers in @code{SImode} to produce a | |
1463 | @code{DImode} result, but only if the registers are correctly sign | |
1464 | extended. This predicate for the input operands accepts a | |
1465 | @code{sign_extend} of an @code{SImode} register. Write the constraint | |
1466 | to indicate the type of register that is required for the operand of the | |
1467 | @code{sign_extend}. | |
1468 | @end ifset | |
1469 | ||
1470 | @node Multi-Alternative | |
1471 | @subsection Multiple Alternative Constraints | |
1472 | @cindex multiple alternative constraints | |
1473 | ||
1474 | Sometimes a single instruction has multiple alternative sets of possible | |
1475 | operands. For example, on the 68000, a logical-or instruction can combine | |
1476 | register or an immediate value into memory, or it can combine any kind of | |
1477 | operand into a register; but it cannot combine one memory location into | |
1478 | another. | |
1479 | ||
1480 | These constraints are represented as multiple alternatives. An alternative | |
1481 | can be described by a series of letters for each operand. The overall | |
1482 | constraint for an operand is made from the letters for this operand | |
1483 | from the first alternative, a comma, the letters for this operand from | |
1484 | the second alternative, a comma, and so on until the last alternative. | |
a6fa947e DW |
1485 | All operands for a single instruction must have the same number of |
1486 | alternatives. | |
03dda8e3 RK |
1487 | @ifset INTERNALS |
1488 | Here is how it is done for fullword logical-or on the 68000: | |
1489 | ||
1490 | @smallexample | |
1491 | (define_insn "iorsi3" | |
1492 | [(set (match_operand:SI 0 "general_operand" "=m,d") | |
1493 | (ior:SI (match_operand:SI 1 "general_operand" "%0,0") | |
1494 | (match_operand:SI 2 "general_operand" "dKs,dmKs")))] | |
1495 | @dots{}) | |
1496 | @end smallexample | |
1497 | ||
1498 | The first alternative has @samp{m} (memory) for operand 0, @samp{0} for | |
1499 | operand 1 (meaning it must match operand 0), and @samp{dKs} for operand | |
1500 | 2. The second alternative has @samp{d} (data register) for operand 0, | |
1501 | @samp{0} for operand 1, and @samp{dmKs} for operand 2. The @samp{=} and | |
1502 | @samp{%} in the constraints apply to all the alternatives; their | |
1503 | meaning is explained in the next section (@pxref{Class Preferences}). | |
03dda8e3 | 1504 | |
03dda8e3 RK |
1505 | If all the operands fit any one alternative, the instruction is valid. |
1506 | Otherwise, for each alternative, the compiler counts how many instructions | |
1507 | must be added to copy the operands so that that alternative applies. | |
1508 | The alternative requiring the least copying is chosen. If two alternatives | |
1509 | need the same amount of copying, the one that comes first is chosen. | |
1510 | These choices can be altered with the @samp{?} and @samp{!} characters: | |
1511 | ||
1512 | @table @code | |
1513 | @cindex @samp{?} in constraint | |
1514 | @cindex question mark | |
1515 | @item ? | |
1516 | Disparage slightly the alternative that the @samp{?} appears in, | |
1517 | as a choice when no alternative applies exactly. The compiler regards | |
1518 | this alternative as one unit more costly for each @samp{?} that appears | |
1519 | in it. | |
1520 | ||
1521 | @cindex @samp{!} in constraint | |
1522 | @cindex exclamation point | |
1523 | @item ! | |
1524 | Disparage severely the alternative that the @samp{!} appears in. | |
1525 | This alternative can still be used if it fits without reloading, | |
1526 | but if reloading is needed, some other alternative will be used. | |
d1457701 VM |
1527 | |
1528 | @cindex @samp{^} in constraint | |
1529 | @cindex caret | |
1530 | @item ^ | |
1531 | This constraint is analogous to @samp{?} but it disparages slightly | |
0ab9eed6 | 1532 | the alternative only if the operand with the @samp{^} needs a reload. |
d1457701 VM |
1533 | |
1534 | @cindex @samp{$} in constraint | |
1535 | @cindex dollar sign | |
1536 | @item $ | |
1537 | This constraint is analogous to @samp{!} but it disparages severely | |
1538 | the alternative only if the operand with the @samp{$} needs a reload. | |
03dda8e3 RK |
1539 | @end table |
1540 | ||
03dda8e3 RK |
1541 | When an insn pattern has multiple alternatives in its constraints, often |
1542 | the appearance of the assembler code is determined mostly by which | |
1543 | alternative was matched. When this is so, the C code for writing the | |
1544 | assembler code can use the variable @code{which_alternative}, which is | |
1545 | the ordinal number of the alternative that was actually satisfied (0 for | |
1546 | the first, 1 for the second alternative, etc.). @xref{Output Statement}. | |
1547 | @end ifset | |
a6fa947e DW |
1548 | @ifclear INTERNALS |
1549 | ||
1550 | So the first alternative for the 68000's logical-or could be written as | |
1551 | @code{"+m" (output) : "ir" (input)}. The second could be @code{"+r" | |
1552 | (output): "irm" (input)}. However, the fact that two memory locations | |
1553 | cannot be used in a single instruction prevents simply using @code{"+rm" | |
1554 | (output) : "irm" (input)}. Using multi-alternatives, this might be | |
1555 | written as @code{"+m,r" (output) : "ir,irm" (input)}. This describes | |
1556 | all the available alternatives to the compiler, allowing it to choose | |
1557 | the most efficient one for the current conditions. | |
1558 | ||
1559 | There is no way within the template to determine which alternative was | |
1560 | chosen. However you may be able to wrap your @code{asm} statements with | |
1561 | builtins such as @code{__builtin_constant_p} to achieve the desired results. | |
1562 | @end ifclear | |
03dda8e3 RK |
1563 | |
1564 | @ifset INTERNALS | |
1565 | @node Class Preferences | |
1566 | @subsection Register Class Preferences | |
1567 | @cindex class preference constraints | |
1568 | @cindex register class preference constraints | |
1569 | ||
1570 | @cindex voting between constraint alternatives | |
1571 | The operand constraints have another function: they enable the compiler | |
1572 | to decide which kind of hardware register a pseudo register is best | |
1573 | allocated to. The compiler examines the constraints that apply to the | |
1574 | insns that use the pseudo register, looking for the machine-dependent | |
1575 | letters such as @samp{d} and @samp{a} that specify classes of registers. | |
1576 | The pseudo register is put in whichever class gets the most ``votes''. | |
1577 | The constraint letters @samp{g} and @samp{r} also vote: they vote in | |
1578 | favor of a general register. The machine description says which registers | |
1579 | are considered general. | |
1580 | ||
1581 | Of course, on some machines all registers are equivalent, and no register | |
1582 | classes are defined. Then none of this complexity is relevant. | |
1583 | @end ifset | |
1584 | ||
1585 | @node Modifiers | |
1586 | @subsection Constraint Modifier Characters | |
1587 | @cindex modifiers in constraints | |
1588 | @cindex constraint modifier characters | |
1589 | ||
1590 | @c prevent bad page break with this line | |
1591 | Here are constraint modifier characters. | |
1592 | ||
1593 | @table @samp | |
1594 | @cindex @samp{=} in constraint | |
1595 | @item = | |
5fd4bc96 JG |
1596 | Means that this operand is written to by this instruction: |
1597 | the previous value is discarded and replaced by new data. | |
03dda8e3 RK |
1598 | |
1599 | @cindex @samp{+} in constraint | |
1600 | @item + | |
1601 | Means that this operand is both read and written by the instruction. | |
1602 | ||
1603 | When the compiler fixes up the operands to satisfy the constraints, | |
5fd4bc96 JG |
1604 | it needs to know which operands are read by the instruction and |
1605 | which are written by it. @samp{=} identifies an operand which is only | |
1606 | written; @samp{+} identifies an operand that is both read and written; all | |
1607 | other operands are assumed to only be read. | |
03dda8e3 | 1608 | |
c5c76735 JL |
1609 | If you specify @samp{=} or @samp{+} in a constraint, you put it in the |
1610 | first character of the constraint string. | |
1611 | ||
03dda8e3 RK |
1612 | @cindex @samp{&} in constraint |
1613 | @cindex earlyclobber operand | |
1614 | @item & | |
1615 | Means (in a particular alternative) that this operand is an | |
5fd4bc96 | 1616 | @dfn{earlyclobber} operand, which is written before the instruction is |
03dda8e3 | 1617 | finished using the input operands. Therefore, this operand may not lie |
5fd4bc96 | 1618 | in a register that is read by the instruction or as part of any memory |
03dda8e3 RK |
1619 | address. |
1620 | ||
1621 | @samp{&} applies only to the alternative in which it is written. In | |
1622 | constraints with multiple alternatives, sometimes one alternative | |
1623 | requires @samp{&} while others do not. See, for example, the | |
1624 | @samp{movdf} insn of the 68000. | |
1625 | ||
5fd4bc96 JG |
1626 | A operand which is read by the instruction can be tied to an earlyclobber |
1627 | operand if its only use as an input occurs before the early result is | |
1628 | written. Adding alternatives of this form often allows GCC to produce | |
1629 | better code when only some of the read operands can be affected by the | |
1630 | earlyclobber. See, for example, the @samp{mulsi3} insn of the ARM@. | |
03dda8e3 | 1631 | |
5fd4bc96 JG |
1632 | Furthermore, if the @dfn{earlyclobber} operand is also a read/write |
1633 | operand, then that operand is written only after it's used. | |
34386e79 | 1634 | |
5fd4bc96 JG |
1635 | @samp{&} does not obviate the need to write @samp{=} or @samp{+}. As |
1636 | @dfn{earlyclobber} operands are always written, a read-only | |
1637 | @dfn{earlyclobber} operand is ill-formed and will be rejected by the | |
1638 | compiler. | |
03dda8e3 RK |
1639 | |
1640 | @cindex @samp{%} in constraint | |
1641 | @item % | |
1642 | Declares the instruction to be commutative for this operand and the | |
1643 | following operand. This means that the compiler may interchange the | |
1644 | two operands if that is the cheapest way to make all operands fit the | |
73f793e3 | 1645 | constraints. @samp{%} applies to all alternatives and must appear as |
5fd4bc96 | 1646 | the first character in the constraint. Only read-only operands can use |
73f793e3 RS |
1647 | @samp{%}. |
1648 | ||
03dda8e3 RK |
1649 | @ifset INTERNALS |
1650 | This is often used in patterns for addition instructions | |
1651 | that really have only two operands: the result must go in one of the | |
1652 | arguments. Here for example, is how the 68000 halfword-add | |
1653 | instruction is defined: | |
1654 | ||
1655 | @smallexample | |
1656 | (define_insn "addhi3" | |
1657 | [(set (match_operand:HI 0 "general_operand" "=m,r") | |
1658 | (plus:HI (match_operand:HI 1 "general_operand" "%0,0") | |
1659 | (match_operand:HI 2 "general_operand" "di,g")))] | |
1660 | @dots{}) | |
1661 | @end smallexample | |
1662 | @end ifset | |
daf2f129 | 1663 | GCC can only handle one commutative pair in an asm; if you use more, |
595163db EB |
1664 | the compiler may fail. Note that you need not use the modifier if |
1665 | the two alternatives are strictly identical; this would only waste | |
4f237f2e DW |
1666 | time in the reload pass. |
1667 | @ifset INTERNALS | |
1668 | The modifier is not operational after | |
be3914df HPN |
1669 | register allocation, so the result of @code{define_peephole2} |
1670 | and @code{define_split}s performed after reload cannot rely on | |
1671 | @samp{%} to make the intended insn match. | |
03dda8e3 RK |
1672 | |
1673 | @cindex @samp{#} in constraint | |
1674 | @item # | |
1675 | Says that all following characters, up to the next comma, are to be | |
1676 | ignored as a constraint. They are significant only for choosing | |
1677 | register preferences. | |
1678 | ||
03dda8e3 RK |
1679 | @cindex @samp{*} in constraint |
1680 | @item * | |
1681 | Says that the following character should be ignored when choosing | |
1682 | register preferences. @samp{*} has no effect on the meaning of the | |
55a2c322 VM |
1683 | constraint as a constraint, and no effect on reloading. For LRA |
1684 | @samp{*} additionally disparages slightly the alternative if the | |
1685 | following character matches the operand. | |
03dda8e3 RK |
1686 | |
1687 | Here is an example: the 68000 has an instruction to sign-extend a | |
1688 | halfword in a data register, and can also sign-extend a value by | |
1689 | copying it into an address register. While either kind of register is | |
1690 | acceptable, the constraints on an address-register destination are | |
1691 | less strict, so it is best if register allocation makes an address | |
1692 | register its goal. Therefore, @samp{*} is used so that the @samp{d} | |
1693 | constraint letter (for data register) is ignored when computing | |
1694 | register preferences. | |
1695 | ||
1696 | @smallexample | |
1697 | (define_insn "extendhisi2" | |
1698 | [(set (match_operand:SI 0 "general_operand" "=*d,a") | |
1699 | (sign_extend:SI | |
1700 | (match_operand:HI 1 "general_operand" "0,g")))] | |
1701 | @dots{}) | |
1702 | @end smallexample | |
1703 | @end ifset | |
1704 | @end table | |
1705 | ||
1706 | @node Machine Constraints | |
1707 | @subsection Constraints for Particular Machines | |
1708 | @cindex machine specific constraints | |
1709 | @cindex constraints, machine specific | |
1710 | ||
1711 | Whenever possible, you should use the general-purpose constraint letters | |
1712 | in @code{asm} arguments, since they will convey meaning more readily to | |
1713 | people reading your code. Failing that, use the constraint letters | |
1714 | that usually have very similar meanings across architectures. The most | |
1715 | commonly used constraints are @samp{m} and @samp{r} (for memory and | |
1716 | general-purpose registers respectively; @pxref{Simple Constraints}), and | |
1717 | @samp{I}, usually the letter indicating the most common | |
1718 | immediate-constant format. | |
1719 | ||
f38840db ZW |
1720 | Each architecture defines additional constraints. These constraints |
1721 | are used by the compiler itself for instruction generation, as well as | |
1722 | for @code{asm} statements; therefore, some of the constraints are not | |
1723 | particularly useful for @code{asm}. Here is a summary of some of the | |
1724 | machine-dependent constraints available on some particular machines; | |
1725 | it includes both constraints that are useful for @code{asm} and | |
1726 | constraints that aren't. The compiler source file mentioned in the | |
1727 | table heading for each architecture is the definitive reference for | |
1728 | the meanings of that architecture's constraints. | |
6ccde948 | 1729 | |
b4fbcb1b | 1730 | @c Please keep this table alphabetized by target! |
03dda8e3 | 1731 | @table @emph |
5c0da018 IB |
1732 | @item AArch64 family---@file{config/aarch64/constraints.md} |
1733 | @table @code | |
1734 | @item k | |
1735 | The stack pointer register (@code{SP}) | |
1736 | ||
1737 | @item w | |
1738 | Floating point or SIMD vector register | |
1739 | ||
1740 | @item I | |
1741 | Integer constant that is valid as an immediate operand in an @code{ADD} | |
1742 | instruction | |
1743 | ||
1744 | @item J | |
1745 | Integer constant that is valid as an immediate operand in a @code{SUB} | |
1746 | instruction (once negated) | |
1747 | ||
1748 | @item K | |
1749 | Integer constant that can be used with a 32-bit logical instruction | |
1750 | ||
1751 | @item L | |
1752 | Integer constant that can be used with a 64-bit logical instruction | |
1753 | ||
1754 | @item M | |
1755 | Integer constant that is valid as an immediate operand in a 32-bit @code{MOV} | |
1756 | pseudo instruction. The @code{MOV} may be assembled to one of several different | |
1757 | machine instructions depending on the value | |
1758 | ||
1759 | @item N | |
1760 | Integer constant that is valid as an immediate operand in a 64-bit @code{MOV} | |
1761 | pseudo instruction | |
1762 | ||
1763 | @item S | |
1764 | An absolute symbolic address or a label reference | |
1765 | ||
1766 | @item Y | |
1767 | Floating point constant zero | |
1768 | ||
1769 | @item Z | |
1770 | Integer constant zero | |
1771 | ||
5c0da018 IB |
1772 | @item Ush |
1773 | The high part (bits 12 and upwards) of the pc-relative address of a symbol | |
1774 | within 4GB of the instruction | |
1775 | ||
1776 | @item Q | |
1777 | A memory address which uses a single base register with no offset | |
1778 | ||
1779 | @item Ump | |
1780 | A memory address suitable for a load/store pair instruction in SI, DI, SF and | |
1781 | DF modes | |
1782 | ||
5c0da018 IB |
1783 | @end table |
1784 | ||
1785 | ||
5d5f6720 JR |
1786 | @item ARC ---@file{config/arc/constraints.md} |
1787 | @table @code | |
1788 | @item q | |
1789 | Registers usable in ARCompact 16-bit instructions: @code{r0}-@code{r3}, | |
1790 | @code{r12}-@code{r15}. This constraint can only match when the @option{-mq} | |
1791 | option is in effect. | |
1792 | ||
1793 | @item e | |
1794 | Registers usable as base-regs of memory addresses in ARCompact 16-bit memory | |
1795 | instructions: @code{r0}-@code{r3}, @code{r12}-@code{r15}, @code{sp}. | |
1796 | This constraint can only match when the @option{-mq} | |
1797 | option is in effect. | |
1798 | @item D | |
1799 | ARC FPX (dpfp) 64-bit registers. @code{D0}, @code{D1}. | |
1800 | ||
1801 | @item I | |
1802 | A signed 12-bit integer constant. | |
1803 | ||
1804 | @item Cal | |
1805 | constant for arithmetic/logical operations. This might be any constant | |
1806 | that can be put into a long immediate by the assmbler or linker without | |
1807 | involving a PIC relocation. | |
1808 | ||
1809 | @item K | |
1810 | A 3-bit unsigned integer constant. | |
1811 | ||
1812 | @item L | |
1813 | A 6-bit unsigned integer constant. | |
1814 | ||
1815 | @item CnL | |
1816 | One's complement of a 6-bit unsigned integer constant. | |
1817 | ||
1818 | @item CmL | |
1819 | Two's complement of a 6-bit unsigned integer constant. | |
1820 | ||
1821 | @item M | |
1822 | A 5-bit unsigned integer constant. | |
1823 | ||
1824 | @item O | |
1825 | A 7-bit unsigned integer constant. | |
1826 | ||
1827 | @item P | |
1828 | A 8-bit unsigned integer constant. | |
1829 | ||
1830 | @item H | |
1831 | Any const_double value. | |
1832 | @end table | |
1833 | ||
dae840fc | 1834 | @item ARM family---@file{config/arm/constraints.md} |
03dda8e3 | 1835 | @table @code |
b24671f7 RR |
1836 | |
1837 | @item h | |
1838 | In Thumb state, the core registers @code{r8}-@code{r15}. | |
1839 | ||
1840 | @item k | |
1841 | The stack pointer register. | |
1842 | ||
1843 | @item l | |
1844 | In Thumb State the core registers @code{r0}-@code{r7}. In ARM state this | |
1845 | is an alias for the @code{r} constraint. | |
1846 | ||
1847 | @item t | |
1848 | VFP floating-point registers @code{s0}-@code{s31}. Used for 32 bit values. | |
1849 | ||
9b66ebb1 | 1850 | @item w |
b24671f7 RR |
1851 | VFP floating-point registers @code{d0}-@code{d31} and the appropriate |
1852 | subset @code{d0}-@code{d15} based on command line options. | |
1853 | Used for 64 bit values only. Not valid for Thumb1. | |
1854 | ||
1855 | @item y | |
1856 | The iWMMX co-processor registers. | |
1857 | ||
1858 | @item z | |
1859 | The iWMMX GR registers. | |
9b66ebb1 | 1860 | |
03dda8e3 | 1861 | @item G |
dae840fc | 1862 | The floating-point constant 0.0 |
03dda8e3 RK |
1863 | |
1864 | @item I | |
1865 | Integer that is valid as an immediate operand in a data processing | |
1866 | instruction. That is, an integer in the range 0 to 255 rotated by a | |
1867 | multiple of 2 | |
1868 | ||
1869 | @item J | |
630d3d5a | 1870 | Integer in the range @minus{}4095 to 4095 |
03dda8e3 RK |
1871 | |
1872 | @item K | |
1873 | Integer that satisfies constraint @samp{I} when inverted (ones complement) | |
1874 | ||
1875 | @item L | |
1876 | Integer that satisfies constraint @samp{I} when negated (twos complement) | |
1877 | ||
1878 | @item M | |
1879 | Integer in the range 0 to 32 | |
1880 | ||
1881 | @item Q | |
1882 | A memory reference where the exact address is in a single register | |
1883 | (`@samp{m}' is preferable for @code{asm} statements) | |
1884 | ||
1885 | @item R | |
1886 | An item in the constant pool | |
1887 | ||
1888 | @item S | |
1889 | A symbol in the text segment of the current file | |
03dda8e3 | 1890 | |
1e1ab407 | 1891 | @item Uv |
9b66ebb1 PB |
1892 | A memory reference suitable for VFP load/store insns (reg+constant offset) |
1893 | ||
fdd695fd PB |
1894 | @item Uy |
1895 | A memory reference suitable for iWMMXt load/store instructions. | |
1896 | ||
1e1ab407 | 1897 | @item Uq |
0bdcd332 | 1898 | A memory reference suitable for the ARMv4 ldrsb instruction. |
db875b15 | 1899 | @end table |
1e1ab407 | 1900 | |
fc262682 | 1901 | @item AVR family---@file{config/avr/constraints.md} |
052a4b28 DC |
1902 | @table @code |
1903 | @item l | |
1904 | Registers from r0 to r15 | |
1905 | ||
1906 | @item a | |
1907 | Registers from r16 to r23 | |
1908 | ||
1909 | @item d | |
1910 | Registers from r16 to r31 | |
1911 | ||
1912 | @item w | |
3a69a7d5 | 1913 | Registers from r24 to r31. These registers can be used in @samp{adiw} command |
052a4b28 DC |
1914 | |
1915 | @item e | |
d7d9c429 | 1916 | Pointer register (r26--r31) |
052a4b28 DC |
1917 | |
1918 | @item b | |
d7d9c429 | 1919 | Base pointer register (r28--r31) |
052a4b28 | 1920 | |
3a69a7d5 MM |
1921 | @item q |
1922 | Stack pointer register (SPH:SPL) | |
1923 | ||
052a4b28 DC |
1924 | @item t |
1925 | Temporary register r0 | |
1926 | ||
1927 | @item x | |
1928 | Register pair X (r27:r26) | |
1929 | ||
1930 | @item y | |
1931 | Register pair Y (r29:r28) | |
1932 | ||
1933 | @item z | |
1934 | Register pair Z (r31:r30) | |
1935 | ||
1936 | @item I | |
630d3d5a | 1937 | Constant greater than @minus{}1, less than 64 |
052a4b28 DC |
1938 | |
1939 | @item J | |
630d3d5a | 1940 | Constant greater than @minus{}64, less than 1 |
052a4b28 DC |
1941 | |
1942 | @item K | |
1943 | Constant integer 2 | |
1944 | ||
1945 | @item L | |
1946 | Constant integer 0 | |
1947 | ||
1948 | @item M | |
1949 | Constant that fits in 8 bits | |
1950 | ||
1951 | @item N | |
630d3d5a | 1952 | Constant integer @minus{}1 |
052a4b28 DC |
1953 | |
1954 | @item O | |
3a69a7d5 | 1955 | Constant integer 8, 16, or 24 |
052a4b28 DC |
1956 | |
1957 | @item P | |
1958 | Constant integer 1 | |
1959 | ||
1960 | @item G | |
1961 | A floating point constant 0.0 | |
0e8eb4d8 | 1962 | |
0e8eb4d8 EW |
1963 | @item Q |
1964 | A memory address based on Y or Z pointer with displacement. | |
052a4b28 | 1965 | @end table |
53054e77 | 1966 | |
b4fbcb1b SL |
1967 | @item Blackfin family---@file{config/bfin/constraints.md} |
1968 | @table @code | |
1969 | @item a | |
1970 | P register | |
1971 | ||
1972 | @item d | |
1973 | D register | |
1974 | ||
1975 | @item z | |
1976 | A call clobbered P register. | |
1977 | ||
1978 | @item q@var{n} | |
1979 | A single register. If @var{n} is in the range 0 to 7, the corresponding D | |
1980 | register. If it is @code{A}, then the register P0. | |
1981 | ||
1982 | @item D | |
1983 | Even-numbered D register | |
1984 | ||
1985 | @item W | |
1986 | Odd-numbered D register | |
1987 | ||
1988 | @item e | |
1989 | Accumulator register. | |
1990 | ||
1991 | @item A | |
1992 | Even-numbered accumulator register. | |
1993 | ||
1994 | @item B | |
1995 | Odd-numbered accumulator register. | |
1996 | ||
1997 | @item b | |
1998 | I register | |
1999 | ||
2000 | @item v | |
2001 | B register | |
2002 | ||
2003 | @item f | |
2004 | M register | |
2005 | ||
2006 | @item c | |
2007 | Registers used for circular buffering, i.e. I, B, or L registers. | |
2008 | ||
2009 | @item C | |
2010 | The CC register. | |
2011 | ||
2012 | @item t | |
2013 | LT0 or LT1. | |
2014 | ||
2015 | @item k | |
2016 | LC0 or LC1. | |
2017 | ||
2018 | @item u | |
2019 | LB0 or LB1. | |
2020 | ||
2021 | @item x | |
2022 | Any D, P, B, M, I or L register. | |
2023 | ||
2024 | @item y | |
2025 | Additional registers typically used only in prologues and epilogues: RETS, | |
2026 | RETN, RETI, RETX, RETE, ASTAT, SEQSTAT and USP. | |
2027 | ||
2028 | @item w | |
2029 | Any register except accumulators or CC. | |
2030 | ||
2031 | @item Ksh | |
2032 | Signed 16 bit integer (in the range @minus{}32768 to 32767) | |
2033 | ||
2034 | @item Kuh | |
2035 | Unsigned 16 bit integer (in the range 0 to 65535) | |
2036 | ||
2037 | @item Ks7 | |
2038 | Signed 7 bit integer (in the range @minus{}64 to 63) | |
2039 | ||
2040 | @item Ku7 | |
2041 | Unsigned 7 bit integer (in the range 0 to 127) | |
2042 | ||
2043 | @item Ku5 | |
2044 | Unsigned 5 bit integer (in the range 0 to 31) | |
2045 | ||
2046 | @item Ks4 | |
2047 | Signed 4 bit integer (in the range @minus{}8 to 7) | |
2048 | ||
2049 | @item Ks3 | |
2050 | Signed 3 bit integer (in the range @minus{}3 to 4) | |
2051 | ||
2052 | @item Ku3 | |
2053 | Unsigned 3 bit integer (in the range 0 to 7) | |
2054 | ||
2055 | @item P@var{n} | |
2056 | Constant @var{n}, where @var{n} is a single-digit constant in the range 0 to 4. | |
2057 | ||
2058 | @item PA | |
2059 | An integer equal to one of the MACFLAG_XXX constants that is suitable for | |
2060 | use with either accumulator. | |
2061 | ||
2062 | @item PB | |
2063 | An integer equal to one of the MACFLAG_XXX constants that is suitable for | |
2064 | use only with accumulator A1. | |
2065 | ||
2066 | @item M1 | |
2067 | Constant 255. | |
2068 | ||
2069 | @item M2 | |
2070 | Constant 65535. | |
2071 | ||
2072 | @item J | |
2073 | An integer constant with exactly a single bit set. | |
2074 | ||
2075 | @item L | |
2076 | An integer constant with all bits set except exactly one. | |
2077 | ||
2078 | @item H | |
2079 | ||
2080 | @item Q | |
2081 | Any SYMBOL_REF. | |
2082 | @end table | |
2083 | ||
2084 | @item CR16 Architecture---@file{config/cr16/cr16.h} | |
2085 | @table @code | |
2086 | ||
2087 | @item b | |
2088 | Registers from r0 to r14 (registers without stack pointer) | |
2089 | ||
2090 | @item t | |
2091 | Register from r0 to r11 (all 16-bit registers) | |
2092 | ||
2093 | @item p | |
2094 | Register from r12 to r15 (all 32-bit registers) | |
2095 | ||
2096 | @item I | |
2097 | Signed constant that fits in 4 bits | |
2098 | ||
2099 | @item J | |
2100 | Signed constant that fits in 5 bits | |
2101 | ||
2102 | @item K | |
2103 | Signed constant that fits in 6 bits | |
2104 | ||
2105 | @item L | |
2106 | Unsigned constant that fits in 4 bits | |
2107 | ||
2108 | @item M | |
2109 | Signed constant that fits in 32 bits | |
2110 | ||
2111 | @item N | |
2112 | Check for 64 bits wide constants for add/sub instructions | |
2113 | ||
2114 | @item G | |
2115 | Floating point constant that is legal for store immediate | |
2116 | @end table | |
2117 | ||
feeeff5c JR |
2118 | @item Epiphany---@file{config/epiphany/constraints.md} |
2119 | @table @code | |
2120 | @item U16 | |
2121 | An unsigned 16-bit constant. | |
2122 | ||
2123 | @item K | |
2124 | An unsigned 5-bit constant. | |
2125 | ||
2126 | @item L | |
2127 | A signed 11-bit constant. | |
2128 | ||
2129 | @item Cm1 | |
2130 | A signed 11-bit constant added to @minus{}1. | |
2131 | Can only match when the @option{-m1reg-@var{reg}} option is active. | |
2132 | ||
2133 | @item Cl1 | |
2134 | Left-shift of @minus{}1, i.e., a bit mask with a block of leading ones, the rest | |
2135 | being a block of trailing zeroes. | |
2136 | Can only match when the @option{-m1reg-@var{reg}} option is active. | |
2137 | ||
2138 | @item Cr1 | |
2139 | Right-shift of @minus{}1, i.e., a bit mask with a trailing block of ones, the | |
2140 | rest being zeroes. Or to put it another way, one less than a power of two. | |
2141 | Can only match when the @option{-m1reg-@var{reg}} option is active. | |
2142 | ||
2143 | @item Cal | |
2144 | Constant for arithmetic/logical operations. | |
2145 | This is like @code{i}, except that for position independent code, | |
2146 | no symbols / expressions needing relocations are allowed. | |
2147 | ||
2148 | @item Csy | |
2149 | Symbolic constant for call/jump instruction. | |
2150 | ||
2151 | @item Rcs | |
2152 | The register class usable in short insns. This is a register class | |
2153 | constraint, and can thus drive register allocation. | |
2154 | This constraint won't match unless @option{-mprefer-short-insn-regs} is | |
2155 | in effect. | |
2156 | ||
2157 | @item Rsc | |
2158 | The the register class of registers that can be used to hold a | |
2159 | sibcall call address. I.e., a caller-saved register. | |
2160 | ||
2161 | @item Rct | |
2162 | Core control register class. | |
2163 | ||
2164 | @item Rgs | |
2165 | The register group usable in short insns. | |
2166 | This constraint does not use a register class, so that it only | |
2167 | passively matches suitable registers, and doesn't drive register allocation. | |
2168 | ||
2169 | @ifset INTERNALS | |
2170 | @item Car | |
2171 | Constant suitable for the addsi3_r pattern. This is a valid offset | |
2172 | For byte, halfword, or word addressing. | |
2173 | @end ifset | |
2174 | ||
2175 | @item Rra | |
2176 | Matches the return address if it can be replaced with the link register. | |
2177 | ||
2178 | @item Rcc | |
2179 | Matches the integer condition code register. | |
2180 | ||
2181 | @item Sra | |
2182 | Matches the return address if it is in a stack slot. | |
2183 | ||
2184 | @item Cfm | |
2185 | Matches control register values to switch fp mode, which are encapsulated in | |
2186 | @code{UNSPEC_FP_MODE}. | |
2187 | @end table | |
2188 | ||
b4fbcb1b | 2189 | @item FRV---@file{config/frv/frv.h} |
b25364a0 | 2190 | @table @code |
b4fbcb1b SL |
2191 | @item a |
2192 | Register in the class @code{ACC_REGS} (@code{acc0} to @code{acc7}). | |
b25364a0 S |
2193 | |
2194 | @item b | |
b4fbcb1b SL |
2195 | Register in the class @code{EVEN_ACC_REGS} (@code{acc0} to @code{acc7}). |
2196 | ||
2197 | @item c | |
2198 | Register in the class @code{CC_REGS} (@code{fcc0} to @code{fcc3} and | |
2199 | @code{icc0} to @code{icc3}). | |
2200 | ||
2201 | @item d | |
2202 | Register in the class @code{GPR_REGS} (@code{gr0} to @code{gr63}). | |
2203 | ||
2204 | @item e | |
2205 | Register in the class @code{EVEN_REGS} (@code{gr0} to @code{gr63}). | |
2206 | Odd registers are excluded not in the class but through the use of a machine | |
2207 | mode larger than 4 bytes. | |
2208 | ||
2209 | @item f | |
2210 | Register in the class @code{FPR_REGS} (@code{fr0} to @code{fr63}). | |
2211 | ||
2212 | @item h | |
2213 | Register in the class @code{FEVEN_REGS} (@code{fr0} to @code{fr63}). | |
2214 | Odd registers are excluded not in the class but through the use of a machine | |
2215 | mode larger than 4 bytes. | |
2216 | ||
2217 | @item l | |
2218 | Register in the class @code{LR_REG} (the @code{lr} register). | |
2219 | ||
2220 | @item q | |
2221 | Register in the class @code{QUAD_REGS} (@code{gr2} to @code{gr63}). | |
2222 | Register numbers not divisible by 4 are excluded not in the class but through | |
2223 | the use of a machine mode larger than 8 bytes. | |
b25364a0 S |
2224 | |
2225 | @item t | |
b4fbcb1b | 2226 | Register in the class @code{ICC_REGS} (@code{icc0} to @code{icc3}). |
b25364a0 | 2227 | |
b4fbcb1b SL |
2228 | @item u |
2229 | Register in the class @code{FCC_REGS} (@code{fcc0} to @code{fcc3}). | |
2230 | ||
2231 | @item v | |
2232 | Register in the class @code{ICR_REGS} (@code{cc4} to @code{cc7}). | |
2233 | ||
2234 | @item w | |
2235 | Register in the class @code{FCR_REGS} (@code{cc0} to @code{cc3}). | |
2236 | ||
2237 | @item x | |
2238 | Register in the class @code{QUAD_FPR_REGS} (@code{fr0} to @code{fr63}). | |
2239 | Register numbers not divisible by 4 are excluded not in the class but through | |
2240 | the use of a machine mode larger than 8 bytes. | |
2241 | ||
2242 | @item z | |
2243 | Register in the class @code{SPR_REGS} (@code{lcr} and @code{lr}). | |
2244 | ||
2245 | @item A | |
2246 | Register in the class @code{QUAD_ACC_REGS} (@code{acc0} to @code{acc7}). | |
2247 | ||
2248 | @item B | |
2249 | Register in the class @code{ACCG_REGS} (@code{accg0} to @code{accg7}). | |
2250 | ||
2251 | @item C | |
2252 | Register in the class @code{CR_REGS} (@code{cc0} to @code{cc7}). | |
2253 | ||
2254 | @item G | |
2255 | Floating point constant zero | |
b25364a0 S |
2256 | |
2257 | @item I | |
b4fbcb1b | 2258 | 6-bit signed integer constant |
b25364a0 S |
2259 | |
2260 | @item J | |
b4fbcb1b | 2261 | 10-bit signed integer constant |
b25364a0 S |
2262 | |
2263 | @item L | |
b4fbcb1b | 2264 | 16-bit signed integer constant |
b25364a0 S |
2265 | |
2266 | @item M | |
b4fbcb1b | 2267 | 16-bit unsigned integer constant |
b25364a0 S |
2268 | |
2269 | @item N | |
b4fbcb1b SL |
2270 | 12-bit signed integer constant that is negative---i.e.@: in the |
2271 | range of @minus{}2048 to @minus{}1 | |
2272 | ||
2273 | @item O | |
2274 | Constant zero | |
2275 | ||
2276 | @item P | |
2277 | 12-bit signed integer constant that is greater than zero---i.e.@: in the | |
2278 | range of 1 to 2047. | |
b25364a0 | 2279 | |
b25364a0 S |
2280 | @end table |
2281 | ||
fef939d6 JB |
2282 | @item FT32---@file{config/ft32/constraints.md} |
2283 | @table @code | |
2284 | @item A | |
2285 | An absolute address | |
2286 | ||
2287 | @item B | |
2288 | An offset address | |
2289 | ||
2290 | @item W | |
2291 | A register indirect memory operand | |
2292 | ||
2293 | @item e | |
2294 | An offset address. | |
2295 | ||
2296 | @item f | |
2297 | An offset address. | |
2298 | ||
2299 | @item O | |
2300 | The constant zero or one | |
2301 | ||
2302 | @item I | |
2303 | A 16-bit signed constant (@minus{}32768 @dots{} 32767) | |
2304 | ||
2305 | @item w | |
2306 | A bitfield mask suitable for bext or bins | |
2307 | ||
2308 | @item x | |
2309 | An inverted bitfield mask suitable for bext or bins | |
2310 | ||
2311 | @item L | |
2312 | A 16-bit unsigned constant, multiple of 4 (0 @dots{} 65532) | |
2313 | ||
2314 | @item S | |
2315 | A 20-bit signed constant (@minus{}524288 @dots{} 524287) | |
2316 | ||
2317 | @item b | |
2318 | A constant for a bitfield width (1 @dots{} 16) | |
2319 | ||
2320 | @item KA | |
2321 | A 10-bit signed constant (@minus{}512 @dots{} 511) | |
2322 | ||
2323 | @end table | |
2324 | ||
8119b4e4 JDA |
2325 | @item Hewlett-Packard PA-RISC---@file{config/pa/pa.h} |
2326 | @table @code | |
2327 | @item a | |
2328 | General register 1 | |
2329 | ||
2330 | @item f | |
2331 | Floating point register | |
2332 | ||
2333 | @item q | |
2334 | Shift amount register | |
2335 | ||
2336 | @item x | |
2337 | Floating point register (deprecated) | |
2338 | ||
2339 | @item y | |
2340 | Upper floating point register (32-bit), floating point register (64-bit) | |
2341 | ||
2342 | @item Z | |
2343 | Any register | |
2344 | ||
2345 | @item I | |
2346 | Signed 11-bit integer constant | |
2347 | ||
2348 | @item J | |
2349 | Signed 14-bit integer constant | |
2350 | ||
2351 | @item K | |
2352 | Integer constant that can be deposited with a @code{zdepi} instruction | |
2353 | ||
2354 | @item L | |
2355 | Signed 5-bit integer constant | |
2356 | ||
2357 | @item M | |
2358 | Integer constant 0 | |
2359 | ||
2360 | @item N | |
2361 | Integer constant that can be loaded with a @code{ldil} instruction | |
2362 | ||
2363 | @item O | |
2364 | Integer constant whose value plus one is a power of 2 | |
2365 | ||
2366 | @item P | |
2367 | Integer constant that can be used for @code{and} operations in @code{depi} | |
2368 | and @code{extru} instructions | |
2369 | ||
2370 | @item S | |
2371 | Integer constant 31 | |
2372 | ||
2373 | @item U | |
2374 | Integer constant 63 | |
2375 | ||
2376 | @item G | |
2377 | Floating-point constant 0.0 | |
2378 | ||
2379 | @item A | |
2380 | A @code{lo_sum} data-linkage-table memory operand | |
2381 | ||
2382 | @item Q | |
2383 | A memory operand that can be used as the destination operand of an | |
2384 | integer store instruction | |
2385 | ||
2386 | @item R | |
2387 | A scaled or unscaled indexed memory operand | |
2388 | ||
2389 | @item T | |
2390 | A memory operand for floating-point loads and stores | |
2391 | ||
2392 | @item W | |
2393 | A register indirect memory operand | |
2394 | @end table | |
2395 | ||
b4fbcb1b | 2396 | @item Intel IA-64---@file{config/ia64/ia64.h} |
03dda8e3 | 2397 | @table @code |
b4fbcb1b SL |
2398 | @item a |
2399 | General register @code{r0} to @code{r3} for @code{addl} instruction | |
03dda8e3 | 2400 | |
b4fbcb1b SL |
2401 | @item b |
2402 | Branch register | |
7a430e3b SC |
2403 | |
2404 | @item c | |
2405 | Predicate register (@samp{c} as in ``conditional'') | |
2406 | ||
b4fbcb1b SL |
2407 | @item d |
2408 | Application register residing in M-unit | |
0d4a78eb | 2409 | |
b4fbcb1b SL |
2410 | @item e |
2411 | Application register residing in I-unit | |
0d4a78eb | 2412 | |
b4fbcb1b SL |
2413 | @item f |
2414 | Floating-point register | |
3efd5670 | 2415 | |
b4fbcb1b SL |
2416 | @item m |
2417 | Memory operand. If used together with @samp{<} or @samp{>}, | |
2418 | the operand can have postincrement and postdecrement which | |
2419 | require printing with @samp{%Pn} on IA-64. | |
3efd5670 | 2420 | |
b4fbcb1b SL |
2421 | @item G |
2422 | Floating-point constant 0.0 or 1.0 | |
0d4a78eb | 2423 | |
b4fbcb1b SL |
2424 | @item I |
2425 | 14-bit signed integer constant | |
0d4a78eb BS |
2426 | |
2427 | @item J | |
b4fbcb1b SL |
2428 | 22-bit signed integer constant |
2429 | ||
2430 | @item K | |
2431 | 8-bit signed integer constant for logical instructions | |
0d4a78eb BS |
2432 | |
2433 | @item L | |
b4fbcb1b | 2434 | 8-bit adjusted signed integer constant for compare pseudo-ops |
0d4a78eb | 2435 | |
b4fbcb1b SL |
2436 | @item M |
2437 | 6-bit unsigned integer constant for shift counts | |
2438 | ||
2439 | @item N | |
2440 | 9-bit signed integer constant for load and store postincrements | |
2441 | ||
2442 | @item O | |
2443 | The constant zero | |
2444 | ||
2445 | @item P | |
2446 | 0 or @minus{}1 for @code{dep} instruction | |
0d4a78eb BS |
2447 | |
2448 | @item Q | |
b4fbcb1b SL |
2449 | Non-volatile memory for floating-point loads and stores |
2450 | ||
2451 | @item R | |
2452 | Integer constant in the range 1 to 4 for @code{shladd} instruction | |
2453 | ||
2454 | @item S | |
2455 | Memory operand except postincrement and postdecrement. This is | |
2456 | now roughly the same as @samp{m} when not used together with @samp{<} | |
2457 | or @samp{>}. | |
0d4a78eb BS |
2458 | @end table |
2459 | ||
74fe790b ZW |
2460 | @item M32C---@file{config/m32c/m32c.c} |
2461 | @table @code | |
38b2d076 DD |
2462 | @item Rsp |
2463 | @itemx Rfb | |
2464 | @itemx Rsb | |
2465 | @samp{$sp}, @samp{$fb}, @samp{$sb}. | |
2466 | ||
2467 | @item Rcr | |
2468 | Any control register, when they're 16 bits wide (nothing if control | |
2469 | registers are 24 bits wide) | |
2470 | ||
2471 | @item Rcl | |
2472 | Any control register, when they're 24 bits wide. | |
2473 | ||
2474 | @item R0w | |
2475 | @itemx R1w | |
2476 | @itemx R2w | |
2477 | @itemx R3w | |
2478 | $r0, $r1, $r2, $r3. | |
2479 | ||
2480 | @item R02 | |
2481 | $r0 or $r2, or $r2r0 for 32 bit values. | |
2482 | ||
2483 | @item R13 | |
2484 | $r1 or $r3, or $r3r1 for 32 bit values. | |
2485 | ||
2486 | @item Rdi | |
2487 | A register that can hold a 64 bit value. | |
2488 | ||
2489 | @item Rhl | |
2490 | $r0 or $r1 (registers with addressable high/low bytes) | |
2491 | ||
2492 | @item R23 | |
2493 | $r2 or $r3 | |
2494 | ||
2495 | @item Raa | |
2496 | Address registers | |
2497 | ||
2498 | @item Raw | |
2499 | Address registers when they're 16 bits wide. | |
2500 | ||
2501 | @item Ral | |
2502 | Address registers when they're 24 bits wide. | |
2503 | ||
2504 | @item Rqi | |
2505 | Registers that can hold QI values. | |
2506 | ||
2507 | @item Rad | |
2508 | Registers that can be used with displacements ($a0, $a1, $sb). | |
2509 | ||
2510 | @item Rsi | |
2511 | Registers that can hold 32 bit values. | |
2512 | ||
2513 | @item Rhi | |
2514 | Registers that can hold 16 bit values. | |
2515 | ||
2516 | @item Rhc | |
2517 | Registers chat can hold 16 bit values, including all control | |
2518 | registers. | |
2519 | ||
2520 | @item Rra | |
2521 | $r0 through R1, plus $a0 and $a1. | |
2522 | ||
2523 | @item Rfl | |
2524 | The flags register. | |
2525 | ||
2526 | @item Rmm | |
2527 | The memory-based pseudo-registers $mem0 through $mem15. | |
2528 | ||
2529 | @item Rpi | |
2530 | Registers that can hold pointers (16 bit registers for r8c, m16c; 24 | |
2531 | bit registers for m32cm, m32c). | |
2532 | ||
2533 | @item Rpa | |
2534 | Matches multiple registers in a PARALLEL to form a larger register. | |
2535 | Used to match function return values. | |
2536 | ||
2537 | @item Is3 | |
8ad1dde7 | 2538 | @minus{}8 @dots{} 7 |
38b2d076 DD |
2539 | |
2540 | @item IS1 | |
8ad1dde7 | 2541 | @minus{}128 @dots{} 127 |
38b2d076 DD |
2542 | |
2543 | @item IS2 | |
8ad1dde7 | 2544 | @minus{}32768 @dots{} 32767 |
38b2d076 DD |
2545 | |
2546 | @item IU2 | |
2547 | 0 @dots{} 65535 | |
2548 | ||
2549 | @item In4 | |
8ad1dde7 | 2550 | @minus{}8 @dots{} @minus{}1 or 1 @dots{} 8 |
38b2d076 DD |
2551 | |
2552 | @item In5 | |
8ad1dde7 | 2553 | @minus{}16 @dots{} @minus{}1 or 1 @dots{} 16 |
38b2d076 | 2554 | |
23fed240 | 2555 | @item In6 |
8ad1dde7 | 2556 | @minus{}32 @dots{} @minus{}1 or 1 @dots{} 32 |
38b2d076 DD |
2557 | |
2558 | @item IM2 | |
8ad1dde7 | 2559 | @minus{}65536 @dots{} @minus{}1 |
38b2d076 DD |
2560 | |
2561 | @item Ilb | |
2562 | An 8 bit value with exactly one bit set. | |
2563 | ||
2564 | @item Ilw | |
2565 | A 16 bit value with exactly one bit set. | |
2566 | ||
2567 | @item Sd | |
2568 | The common src/dest memory addressing modes. | |
2569 | ||
2570 | @item Sa | |
2571 | Memory addressed using $a0 or $a1. | |
2572 | ||
2573 | @item Si | |
2574 | Memory addressed with immediate addresses. | |
2575 | ||
2576 | @item Ss | |
2577 | Memory addressed using the stack pointer ($sp). | |
2578 | ||
2579 | @item Sf | |
2580 | Memory addressed using the frame base register ($fb). | |
2581 | ||
2582 | @item Ss | |
2583 | Memory addressed using the small base register ($sb). | |
2584 | ||
2585 | @item S1 | |
2586 | $r1h | |
e2491744 DD |
2587 | @end table |
2588 | ||
80920132 ME |
2589 | @item MicroBlaze---@file{config/microblaze/constraints.md} |
2590 | @table @code | |
2591 | @item d | |
2592 | A general register (@code{r0} to @code{r31}). | |
2593 | ||
2594 | @item z | |
2595 | A status register (@code{rmsr}, @code{$fcc1} to @code{$fcc7}). | |
e2491744 | 2596 | |
74fe790b | 2597 | @end table |
38b2d076 | 2598 | |
cbbb5b6d | 2599 | @item MIPS---@file{config/mips/constraints.md} |
4226378a PK |
2600 | @table @code |
2601 | @item d | |
0cb14750 MR |
2602 | A general-purpose register. This is equivalent to @code{r} unless |
2603 | generating MIPS16 code, in which case the MIPS16 register set is used. | |
4226378a PK |
2604 | |
2605 | @item f | |
cbbb5b6d | 2606 | A floating-point register (if available). |
4226378a PK |
2607 | |
2608 | @item h | |
21dfc6dc | 2609 | Formerly the @code{hi} register. This constraint is no longer supported. |
4226378a PK |
2610 | |
2611 | @item l | |
21dfc6dc RS |
2612 | The @code{lo} register. Use this register to store values that are |
2613 | no bigger than a word. | |
4226378a PK |
2614 | |
2615 | @item x | |
21dfc6dc RS |
2616 | The concatenated @code{hi} and @code{lo} registers. Use this register |
2617 | to store doubleword values. | |
cbbb5b6d RS |
2618 | |
2619 | @item c | |
2620 | A register suitable for use in an indirect jump. This will always be | |
2621 | @code{$25} for @option{-mabicalls}. | |
4226378a | 2622 | |
2feaae20 RS |
2623 | @item v |
2624 | Register @code{$3}. Do not use this constraint in new code; | |
2625 | it is retained only for compatibility with glibc. | |
2626 | ||
4226378a | 2627 | @item y |
cbbb5b6d | 2628 | Equivalent to @code{r}; retained for backwards compatibility. |
4226378a PK |
2629 | |
2630 | @item z | |
cbbb5b6d | 2631 | A floating-point condition code register. |
4226378a PK |
2632 | |
2633 | @item I | |
cbbb5b6d | 2634 | A signed 16-bit constant (for arithmetic instructions). |
4226378a PK |
2635 | |
2636 | @item J | |
cbbb5b6d | 2637 | Integer zero. |
4226378a PK |
2638 | |
2639 | @item K | |
cbbb5b6d | 2640 | An unsigned 16-bit constant (for logic instructions). |
4226378a PK |
2641 | |
2642 | @item L | |
cbbb5b6d RS |
2643 | A signed 32-bit constant in which the lower 16 bits are zero. |
2644 | Such constants can be loaded using @code{lui}. | |
4226378a PK |
2645 | |
2646 | @item M | |
cbbb5b6d RS |
2647 | A constant that cannot be loaded using @code{lui}, @code{addiu} |
2648 | or @code{ori}. | |
4226378a PK |
2649 | |
2650 | @item N | |
8ad1dde7 | 2651 | A constant in the range @minus{}65535 to @minus{}1 (inclusive). |
4226378a PK |
2652 | |
2653 | @item O | |
cbbb5b6d | 2654 | A signed 15-bit constant. |
4226378a PK |
2655 | |
2656 | @item P | |
cbbb5b6d | 2657 | A constant in the range 1 to 65535 (inclusive). |
4226378a PK |
2658 | |
2659 | @item G | |
cbbb5b6d | 2660 | Floating-point zero. |
4226378a PK |
2661 | |
2662 | @item R | |
cbbb5b6d | 2663 | An address that can be used in a non-macro load or store. |
22c4c869 CM |
2664 | |
2665 | @item ZC | |
047b52f6 MF |
2666 | A memory operand whose address is formed by a base register and offset |
2667 | that is suitable for use in instructions with the same addressing mode | |
2668 | as @code{ll} and @code{sc}. | |
22c4c869 CM |
2669 | |
2670 | @item ZD | |
82f84ecb MF |
2671 | An address suitable for a @code{prefetch} instruction, or for any other |
2672 | instruction with the same addressing mode as @code{prefetch}. | |
4226378a PK |
2673 | @end table |
2674 | ||
c47b0cb4 | 2675 | @item Motorola 680x0---@file{config/m68k/constraints.md} |
03dda8e3 RK |
2676 | @table @code |
2677 | @item a | |
2678 | Address register | |
2679 | ||
2680 | @item d | |
2681 | Data register | |
2682 | ||
2683 | @item f | |
2684 | 68881 floating-point register, if available | |
2685 | ||
03dda8e3 RK |
2686 | @item I |
2687 | Integer in the range 1 to 8 | |
2688 | ||
2689 | @item J | |
1e5f973d | 2690 | 16-bit signed number |
03dda8e3 RK |
2691 | |
2692 | @item K | |
2693 | Signed number whose magnitude is greater than 0x80 | |
2694 | ||
2695 | @item L | |
630d3d5a | 2696 | Integer in the range @minus{}8 to @minus{}1 |
03dda8e3 RK |
2697 | |
2698 | @item M | |
2699 | Signed number whose magnitude is greater than 0x100 | |
2700 | ||
c47b0cb4 MK |
2701 | @item N |
2702 | Range 24 to 31, rotatert:SI 8 to 1 expressed as rotate | |
2703 | ||
2704 | @item O | |
2705 | 16 (for rotate using swap) | |
2706 | ||
2707 | @item P | |
2708 | Range 8 to 15, rotatert:HI 8 to 1 expressed as rotate | |
2709 | ||
2710 | @item R | |
2711 | Numbers that mov3q can handle | |
2712 | ||
03dda8e3 RK |
2713 | @item G |
2714 | Floating point constant that is not a 68881 constant | |
c47b0cb4 MK |
2715 | |
2716 | @item S | |
2717 | Operands that satisfy 'm' when -mpcrel is in effect | |
2718 | ||
2719 | @item T | |
2720 | Operands that satisfy 's' when -mpcrel is not in effect | |
2721 | ||
2722 | @item Q | |
2723 | Address register indirect addressing mode | |
2724 | ||
2725 | @item U | |
2726 | Register offset addressing | |
2727 | ||
2728 | @item W | |
2729 | const_call_operand | |
2730 | ||
2731 | @item Cs | |
2732 | symbol_ref or const | |
2733 | ||
2734 | @item Ci | |
2735 | const_int | |
2736 | ||
2737 | @item C0 | |
2738 | const_int 0 | |
2739 | ||
2740 | @item Cj | |
2741 | Range of signed numbers that don't fit in 16 bits | |
2742 | ||
2743 | @item Cmvq | |
2744 | Integers valid for mvq | |
2745 | ||
2746 | @item Capsw | |
2747 | Integers valid for a moveq followed by a swap | |
2748 | ||
2749 | @item Cmvz | |
2750 | Integers valid for mvz | |
2751 | ||
2752 | @item Cmvs | |
2753 | Integers valid for mvs | |
2754 | ||
2755 | @item Ap | |
2756 | push_operand | |
2757 | ||
2758 | @item Ac | |
2759 | Non-register operands allowed in clr | |
2760 | ||
03dda8e3 RK |
2761 | @end table |
2762 | ||
cceb575c AG |
2763 | @item Moxie---@file{config/moxie/constraints.md} |
2764 | @table @code | |
2765 | @item A | |
2766 | An absolute address | |
2767 | ||
2768 | @item B | |
2769 | An offset address | |
2770 | ||
2771 | @item W | |
2772 | A register indirect memory operand | |
2773 | ||
2774 | @item I | |
2775 | A constant in the range of 0 to 255. | |
2776 | ||
2777 | @item N | |
8ad1dde7 | 2778 | A constant in the range of 0 to @minus{}255. |
cceb575c AG |
2779 | |
2780 | @end table | |
2781 | ||
f6a83b4a DD |
2782 | @item MSP430--@file{config/msp430/constraints.md} |
2783 | @table @code | |
2784 | ||
2785 | @item R12 | |
2786 | Register R12. | |
2787 | ||
2788 | @item R13 | |
2789 | Register R13. | |
2790 | ||
2791 | @item K | |
2792 | Integer constant 1. | |
2793 | ||
2794 | @item L | |
2795 | Integer constant -1^20..1^19. | |
2796 | ||
2797 | @item M | |
2798 | Integer constant 1-4. | |
2799 | ||
2800 | @item Ya | |
2801 | Memory references which do not require an extended MOVX instruction. | |
2802 | ||
2803 | @item Yl | |
2804 | Memory reference, labels only. | |
2805 | ||
2806 | @item Ys | |
2807 | Memory reference, stack only. | |
2808 | ||
2809 | @end table | |
2810 | ||
9304f876 CJW |
2811 | @item NDS32---@file{config/nds32/constraints.md} |
2812 | @table @code | |
2813 | @item w | |
2814 | LOW register class $r0 to $r7 constraint for V3/V3M ISA. | |
2815 | @item l | |
2816 | LOW register class $r0 to $r7. | |
2817 | @item d | |
2818 | MIDDLE register class $r0 to $r11, $r16 to $r19. | |
2819 | @item h | |
2820 | HIGH register class $r12 to $r14, $r20 to $r31. | |
2821 | @item t | |
2822 | Temporary assist register $ta (i.e.@: $r15). | |
2823 | @item k | |
2824 | Stack register $sp. | |
2825 | @item Iu03 | |
2826 | Unsigned immediate 3-bit value. | |
2827 | @item In03 | |
2828 | Negative immediate 3-bit value in the range of @minus{}7--0. | |
2829 | @item Iu04 | |
2830 | Unsigned immediate 4-bit value. | |
2831 | @item Is05 | |
2832 | Signed immediate 5-bit value. | |
2833 | @item Iu05 | |
2834 | Unsigned immediate 5-bit value. | |
2835 | @item In05 | |
2836 | Negative immediate 5-bit value in the range of @minus{}31--0. | |
2837 | @item Ip05 | |
2838 | Unsigned immediate 5-bit value for movpi45 instruction with range 16--47. | |
2839 | @item Iu06 | |
2840 | Unsigned immediate 6-bit value constraint for addri36.sp instruction. | |
2841 | @item Iu08 | |
2842 | Unsigned immediate 8-bit value. | |
2843 | @item Iu09 | |
2844 | Unsigned immediate 9-bit value. | |
2845 | @item Is10 | |
2846 | Signed immediate 10-bit value. | |
2847 | @item Is11 | |
2848 | Signed immediate 11-bit value. | |
2849 | @item Is15 | |
2850 | Signed immediate 15-bit value. | |
2851 | @item Iu15 | |
2852 | Unsigned immediate 15-bit value. | |
2853 | @item Ic15 | |
2854 | A constant which is not in the range of imm15u but ok for bclr instruction. | |
2855 | @item Ie15 | |
2856 | A constant which is not in the range of imm15u but ok for bset instruction. | |
2857 | @item It15 | |
2858 | A constant which is not in the range of imm15u but ok for btgl instruction. | |
2859 | @item Ii15 | |
2860 | A constant whose compliment value is in the range of imm15u | |
2861 | and ok for bitci instruction. | |
2862 | @item Is16 | |
2863 | Signed immediate 16-bit value. | |
2864 | @item Is17 | |
2865 | Signed immediate 17-bit value. | |
2866 | @item Is19 | |
2867 | Signed immediate 19-bit value. | |
2868 | @item Is20 | |
2869 | Signed immediate 20-bit value. | |
2870 | @item Ihig | |
2871 | The immediate value that can be simply set high 20-bit. | |
2872 | @item Izeb | |
2873 | The immediate value 0xff. | |
2874 | @item Izeh | |
2875 | The immediate value 0xffff. | |
2876 | @item Ixls | |
2877 | The immediate value 0x01. | |
2878 | @item Ix11 | |
2879 | The immediate value 0x7ff. | |
2880 | @item Ibms | |
2881 | The immediate value with power of 2. | |
2882 | @item Ifex | |
2883 | The immediate value with power of 2 minus 1. | |
2884 | @item U33 | |
2885 | Memory constraint for 333 format. | |
2886 | @item U45 | |
2887 | Memory constraint for 45 format. | |
2888 | @item U37 | |
2889 | Memory constraint for 37 format. | |
2890 | @end table | |
2891 | ||
e430824f CLT |
2892 | @item Nios II family---@file{config/nios2/constraints.md} |
2893 | @table @code | |
2894 | ||
2895 | @item I | |
2896 | Integer that is valid as an immediate operand in an | |
2897 | instruction taking a signed 16-bit number. Range | |
2898 | @minus{}32768 to 32767. | |
2899 | ||
2900 | @item J | |
2901 | Integer that is valid as an immediate operand in an | |
2902 | instruction taking an unsigned 16-bit number. Range | |
2903 | 0 to 65535. | |
2904 | ||
2905 | @item K | |
2906 | Integer that is valid as an immediate operand in an | |
2907 | instruction taking only the upper 16-bits of a | |
2908 | 32-bit number. Range 32-bit numbers with the lower | |
2909 | 16-bits being 0. | |
2910 | ||
2911 | @item L | |
2912 | Integer that is valid as an immediate operand for a | |
2913 | shift instruction. Range 0 to 31. | |
2914 | ||
2915 | @item M | |
2916 | Integer that is valid as an immediate operand for | |
2917 | only the value 0. Can be used in conjunction with | |
2918 | the format modifier @code{z} to use @code{r0} | |
2919 | instead of @code{0} in the assembly output. | |
2920 | ||
2921 | @item N | |
2922 | Integer that is valid as an immediate operand for | |
2923 | a custom instruction opcode. Range 0 to 255. | |
2924 | ||
3bbbe009 SL |
2925 | @item P |
2926 | An immediate operand for R2 andchi/andci instructions. | |
2927 | ||
e430824f CLT |
2928 | @item S |
2929 | Matches immediates which are addresses in the small | |
2930 | data section and therefore can be added to @code{gp} | |
2931 | as a 16-bit immediate to re-create their 32-bit value. | |
2932 | ||
524d2e49 SL |
2933 | @item U |
2934 | Matches constants suitable as an operand for the rdprs and | |
2935 | cache instructions. | |
2936 | ||
2937 | @item v | |
2938 | A memory operand suitable for Nios II R2 load/store | |
2939 | exclusive instructions. | |
2940 | ||
42e6ab74 SL |
2941 | @item w |
2942 | A memory operand suitable for load/store IO and cache | |
2943 | instructions. | |
2944 | ||
e430824f CLT |
2945 | @ifset INTERNALS |
2946 | @item T | |
2947 | A @code{const} wrapped @code{UNSPEC} expression, | |
2948 | representing a supported PIC or TLS relocation. | |
2949 | @end ifset | |
2950 | ||
2951 | @end table | |
2952 | ||
5e426dd4 PK |
2953 | @item PDP-11---@file{config/pdp11/constraints.md} |
2954 | @table @code | |
2955 | @item a | |
2956 | Floating point registers AC0 through AC3. These can be loaded from/to | |
2957 | memory with a single instruction. | |
2958 | ||
2959 | @item d | |
868e54d1 PK |
2960 | Odd numbered general registers (R1, R3, R5). These are used for |
2961 | 16-bit multiply operations. | |
5e426dd4 PK |
2962 | |
2963 | @item f | |
2964 | Any of the floating point registers (AC0 through AC5). | |
2965 | ||
2966 | @item G | |
2967 | Floating point constant 0. | |
2968 | ||
2969 | @item I | |
2970 | An integer constant that fits in 16 bits. | |
2971 | ||
b4fbcb1b SL |
2972 | @item J |
2973 | An integer constant whose low order 16 bits are zero. | |
2974 | ||
2975 | @item K | |
2976 | An integer constant that does not meet the constraints for codes | |
2977 | @samp{I} or @samp{J}. | |
2978 | ||
2979 | @item L | |
2980 | The integer constant 1. | |
2981 | ||
2982 | @item M | |
2983 | The integer constant @minus{}1. | |
2984 | ||
2985 | @item N | |
2986 | The integer constant 0. | |
2987 | ||
2988 | @item O | |
2989 | Integer constants @minus{}4 through @minus{}1 and 1 through 4; shifts by these | |
2990 | amounts are handled as multiple single-bit shifts rather than a single | |
2991 | variable-length shift. | |
2992 | ||
2993 | @item Q | |
2994 | A memory reference which requires an additional word (address or | |
2995 | offset) after the opcode. | |
2996 | ||
2997 | @item R | |
2998 | A memory reference that is encoded within the opcode. | |
2999 | ||
3000 | @end table | |
3001 | ||
3002 | @item PowerPC and IBM RS6000---@file{config/rs6000/constraints.md} | |
3003 | @table @code | |
3004 | @item b | |
3005 | Address base register | |
3006 | ||
3007 | @item d | |
3008 | Floating point register (containing 64-bit value) | |
3009 | ||
3010 | @item f | |
3011 | Floating point register (containing 32-bit value) | |
3012 | ||
3013 | @item v | |
3014 | Altivec vector register | |
3015 | ||
3016 | @item wa | |
dc703d70 | 3017 | Any VSX register if the @option{-mvsx} option was used or NO_REGS. |
b4fbcb1b | 3018 | |
6a116f14 MM |
3019 | When using any of the register constraints (@code{wa}, @code{wd}, |
3020 | @code{wf}, @code{wg}, @code{wh}, @code{wi}, @code{wj}, @code{wk}, | |
4e8a3a35 MM |
3021 | @code{wl}, @code{wm}, @code{wo}, @code{wp}, @code{wq}, @code{ws}, |
3022 | @code{wt}, @code{wu}, @code{wv}, @code{ww}, or @code{wy}) | |
c477a667 MM |
3023 | that take VSX registers, you must use @code{%x<n>} in the template so |
3024 | that the correct register is used. Otherwise the register number | |
3025 | output in the assembly file will be incorrect if an Altivec register | |
3026 | is an operand of a VSX instruction that expects VSX register | |
3027 | numbering. | |
6a116f14 MM |
3028 | |
3029 | @smallexample | |
dc703d70 SL |
3030 | asm ("xvadddp %x0,%x1,%x2" |
3031 | : "=wa" (v1) | |
3032 | : "wa" (v2), "wa" (v3)); | |
6a116f14 MM |
3033 | @end smallexample |
3034 | ||
dc703d70 | 3035 | @noindent |
6a116f14 MM |
3036 | is correct, but: |
3037 | ||
3038 | @smallexample | |
dc703d70 SL |
3039 | asm ("xvadddp %0,%1,%2" |
3040 | : "=wa" (v1) | |
3041 | : "wa" (v2), "wa" (v3)); | |
6a116f14 MM |
3042 | @end smallexample |
3043 | ||
dc703d70 | 3044 | @noindent |
6a116f14 MM |
3045 | is not correct. |
3046 | ||
dd551aa1 MM |
3047 | If an instruction only takes Altivec registers, you do not want to use |
3048 | @code{%x<n>}. | |
3049 | ||
3050 | @smallexample | |
dc703d70 SL |
3051 | asm ("xsaddqp %0,%1,%2" |
3052 | : "=v" (v1) | |
3053 | : "v" (v2), "v" (v3)); | |
dd551aa1 MM |
3054 | @end smallexample |
3055 | ||
dc703d70 | 3056 | @noindent |
dd551aa1 MM |
3057 | is correct because the @code{xsaddqp} instruction only takes Altivec |
3058 | registers, while: | |
3059 | ||
3060 | @smallexample | |
dc703d70 SL |
3061 | asm ("xsaddqp %x0,%x1,%x2" |
3062 | : "=v" (v1) | |
3063 | : "v" (v2), "v" (v3)); | |
dd551aa1 MM |
3064 | @end smallexample |
3065 | ||
dc703d70 | 3066 | @noindent |
dd551aa1 MM |
3067 | is incorrect. |
3068 | ||
d5906efc | 3069 | @item wb |
1610d410 | 3070 | Altivec register if @option{-mcpu=power9} is used or NO_REGS. |
d5906efc | 3071 | |
b4fbcb1b SL |
3072 | @item wd |
3073 | VSX vector register to hold vector double data or NO_REGS. | |
3074 | ||
dd551aa1 | 3075 | @item we |
1610d410 | 3076 | VSX register if the @option{-mcpu=power9} and @option{-m64} options |
d5906efc | 3077 | were used or NO_REGS. |
dd551aa1 | 3078 | |
b4fbcb1b SL |
3079 | @item wf |
3080 | VSX vector register to hold vector float data or NO_REGS. | |
3081 | ||
3082 | @item wg | |
3083 | If @option{-mmfpgpr} was used, a floating point register or NO_REGS. | |
3084 | ||
3085 | @item wh | |
3086 | Floating point register if direct moves are available, or NO_REGS. | |
3087 | ||
3088 | @item wi | |
3089 | FP or VSX register to hold 64-bit integers for VSX insns or NO_REGS. | |
3090 | ||
3091 | @item wj | |
3092 | FP or VSX register to hold 64-bit integers for direct moves or NO_REGS. | |
3093 | ||
3094 | @item wk | |
3095 | FP or VSX register to hold 64-bit doubles for direct moves or NO_REGS. | |
3096 | ||
3097 | @item wl | |
3098 | Floating point register if the LFIWAX instruction is enabled or NO_REGS. | |
3099 | ||
3100 | @item wm | |
3101 | VSX register if direct move instructions are enabled, or NO_REGS. | |
3102 | ||
3103 | @item wn | |
3104 | No register (NO_REGS). | |
3105 | ||
4e8a3a35 MM |
3106 | @item wo |
3107 | VSX register to use for ISA 3.0 vector instructions, or NO_REGS. | |
3108 | ||
c477a667 MM |
3109 | @item wp |
3110 | VSX register to use for IEEE 128-bit floating point TFmode, or NO_REGS. | |
3111 | ||
3112 | @item wq | |
3113 | VSX register to use for IEEE 128-bit floating point, or NO_REGS. | |
3114 | ||
b4fbcb1b SL |
3115 | @item wr |
3116 | General purpose register if 64-bit instructions are enabled or NO_REGS. | |
3117 | ||
3118 | @item ws | |
3119 | VSX vector register to hold scalar double values or NO_REGS. | |
3120 | ||
3121 | @item wt | |
3122 | VSX vector register to hold 128 bit integer or NO_REGS. | |
3123 | ||
3124 | @item wu | |
3125 | Altivec register to use for float/32-bit int loads/stores or NO_REGS. | |
3126 | ||
3127 | @item wv | |
3128 | Altivec register to use for double loads/stores or NO_REGS. | |
3129 | ||
3130 | @item ww | |
3131 | FP or VSX register to perform float operations under @option{-mvsx} or NO_REGS. | |
3132 | ||
3133 | @item wx | |
3134 | Floating point register if the STFIWX instruction is enabled or NO_REGS. | |
3135 | ||
3136 | @item wy | |
3137 | FP or VSX register to perform ISA 2.07 float ops or NO_REGS. | |
3138 | ||
3139 | @item wz | |
3140 | Floating point register if the LFIWZX instruction is enabled or NO_REGS. | |
3141 | ||
99211352 AS |
3142 | @item wA |
3143 | Address base register if 64-bit instructions are enabled or NO_REGS. | |
3144 | ||
1a3c3ee9 MM |
3145 | @item wB |
3146 | Signed 5-bit constant integer that can be loaded into an altivec register. | |
3147 | ||
b4fbcb1b SL |
3148 | @item wD |
3149 | Int constant that is the element number of the 64-bit scalar in a vector. | |
3150 | ||
50c78b9a MM |
3151 | @item wE |
3152 | Vector constant that can be loaded with the XXSPLTIB instruction. | |
3153 | ||
dd551aa1 MM |
3154 | @item wF |
3155 | Memory operand suitable for power9 fusion load/stores. | |
3156 | ||
3157 | @item wG | |
3158 | Memory operand suitable for TOC fusion memory references. | |
3159 | ||
787c7a65 MM |
3160 | @item wH |
3161 | Altivec register if @option{-mvsx-small-integer}. | |
3162 | ||
3163 | @item wI | |
3164 | Floating point register if @option{-mvsx-small-integer}. | |
3165 | ||
3166 | @item wJ | |
3167 | FP register if @option{-mvsx-small-integer} and @option{-mpower9-vector}. | |
3168 | ||
3169 | @item wK | |
3170 | Altivec register if @option{-mvsx-small-integer} and @option{-mpower9-vector}. | |
3171 | ||
dd551aa1 | 3172 | @item wL |
50c78b9a | 3173 | Int constant that is the element number that the MFVSRLD instruction. |
dd551aa1 MM |
3174 | targets. |
3175 | ||
50c78b9a MM |
3176 | @item wM |
3177 | Match vector constant with all 1's if the XXLORC instruction is available. | |
3178 | ||
3fd2b007 MM |
3179 | @item wO |
3180 | A memory operand suitable for the ISA 3.0 vector d-form instructions. | |
3181 | ||
b4fbcb1b SL |
3182 | @item wQ |
3183 | A memory address that will work with the @code{lq} and @code{stq} | |
3184 | instructions. | |
3185 | ||
50c78b9a MM |
3186 | @item wS |
3187 | Vector constant that can be loaded with XXSPLTIB & sign extension. | |
3188 | ||
b4fbcb1b SL |
3189 | @item h |
3190 | @samp{MQ}, @samp{CTR}, or @samp{LINK} register | |
3191 | ||
b4fbcb1b SL |
3192 | @item c |
3193 | @samp{CTR} register | |
3194 | ||
3195 | @item l | |
3196 | @samp{LINK} register | |
3197 | ||
3198 | @item x | |
3199 | @samp{CR} register (condition register) number 0 | |
3200 | ||
3201 | @item y | |
3202 | @samp{CR} register (condition register) | |
3203 | ||
3204 | @item z | |
3205 | @samp{XER[CA]} carry bit (part of the XER register) | |
3206 | ||
3207 | @item I | |
3208 | Signed 16-bit constant | |
3209 | ||
3210 | @item J | |
3211 | Unsigned 16-bit constant shifted left 16 bits (use @samp{L} instead for | |
3212 | @code{SImode} constants) | |
3213 | ||
3214 | @item K | |
3215 | Unsigned 16-bit constant | |
3216 | ||
3217 | @item L | |
3218 | Signed 16-bit constant shifted left 16 bits | |
3219 | ||
3220 | @item M | |
3221 | Constant larger than 31 | |
3222 | ||
3223 | @item N | |
3224 | Exact power of 2 | |
3225 | ||
3226 | @item O | |
3227 | Zero | |
3228 | ||
3229 | @item P | |
3230 | Constant whose negation is a signed 16-bit constant | |
3231 | ||
3232 | @item G | |
3233 | Floating point constant that can be loaded into a register with one | |
3234 | instruction per word | |
3235 | ||
3236 | @item H | |
3237 | Integer/Floating point constant that can be loaded into a register using | |
3238 | three instructions | |
3239 | ||
3240 | @item m | |
3241 | Memory operand. | |
3242 | Normally, @code{m} does not allow addresses that update the base register. | |
3243 | If @samp{<} or @samp{>} constraint is also used, they are allowed and | |
3244 | therefore on PowerPC targets in that case it is only safe | |
3245 | to use @samp{m<>} in an @code{asm} statement if that @code{asm} statement | |
3246 | accesses the operand exactly once. The @code{asm} statement must also | |
3247 | use @samp{%U@var{<opno>}} as a placeholder for the ``update'' flag in the | |
3248 | corresponding load or store instruction. For example: | |
3249 | ||
3250 | @smallexample | |
3251 | asm ("st%U0 %1,%0" : "=m<>" (mem) : "r" (val)); | |
3252 | @end smallexample | |
3253 | ||
3254 | is correct but: | |
3255 | ||
3256 | @smallexample | |
3257 | asm ("st %1,%0" : "=m<>" (mem) : "r" (val)); | |
3258 | @end smallexample | |
3259 | ||
3260 | is not. | |
3261 | ||
3262 | @item es | |
3263 | A ``stable'' memory operand; that is, one which does not include any | |
3264 | automodification of the base register. This used to be useful when | |
3265 | @samp{m} allowed automodification of the base register, but as those are now only | |
3266 | allowed when @samp{<} or @samp{>} is used, @samp{es} is basically the same | |
3267 | as @samp{m} without @samp{<} and @samp{>}. | |
3268 | ||
3269 | @item Q | |
3270 | Memory operand that is an offset from a register (it is usually better | |
3271 | to use @samp{m} or @samp{es} in @code{asm} statements) | |
3272 | ||
3273 | @item Z | |
3274 | Memory operand that is an indexed or indirect from a register (it is | |
3275 | usually better to use @samp{m} or @samp{es} in @code{asm} statements) | |
3276 | ||
3277 | @item R | |
3278 | AIX TOC entry | |
5e426dd4 | 3279 | |
b4fbcb1b SL |
3280 | @item a |
3281 | Address operand that is an indexed or indirect from a register (@samp{p} is | |
3282 | preferable for @code{asm} statements) | |
5e426dd4 | 3283 | |
b4fbcb1b SL |
3284 | @item U |
3285 | System V Release 4 small data area reference | |
5e426dd4 | 3286 | |
b4fbcb1b SL |
3287 | @item W |
3288 | Vector constant that does not require memory | |
5e426dd4 | 3289 | |
b4fbcb1b SL |
3290 | @item j |
3291 | Vector constant that is all zeros. | |
5e426dd4 PK |
3292 | |
3293 | @end table | |
3294 | ||
85b8555e DD |
3295 | @item RL78---@file{config/rl78/constraints.md} |
3296 | @table @code | |
3297 | ||
3298 | @item Int3 | |
3299 | An integer constant in the range 1 @dots{} 7. | |
3300 | @item Int8 | |
3301 | An integer constant in the range 0 @dots{} 255. | |
3302 | @item J | |
3303 | An integer constant in the range @minus{}255 @dots{} 0 | |
3304 | @item K | |
3305 | The integer constant 1. | |
3306 | @item L | |
3307 | The integer constant -1. | |
3308 | @item M | |
3309 | The integer constant 0. | |
3310 | @item N | |
3311 | The integer constant 2. | |
3312 | @item O | |
3313 | The integer constant -2. | |
3314 | @item P | |
3315 | An integer constant in the range 1 @dots{} 15. | |
3316 | @item Qbi | |
3317 | The built-in compare types--eq, ne, gtu, ltu, geu, and leu. | |
3318 | @item Qsc | |
3319 | The synthetic compare types--gt, lt, ge, and le. | |
3320 | @item Wab | |
3321 | A memory reference with an absolute address. | |
3322 | @item Wbc | |
3323 | A memory reference using @code{BC} as a base register, with an optional offset. | |
3324 | @item Wca | |
3325 | A memory reference using @code{AX}, @code{BC}, @code{DE}, or @code{HL} for the address, for calls. | |
3326 | @item Wcv | |
3327 | A memory reference using any 16-bit register pair for the address, for calls. | |
3328 | @item Wd2 | |
3329 | A memory reference using @code{DE} as a base register, with an optional offset. | |
3330 | @item Wde | |
3331 | A memory reference using @code{DE} as a base register, without any offset. | |
3332 | @item Wfr | |
3333 | Any memory reference to an address in the far address space. | |
3334 | @item Wh1 | |
3335 | A memory reference using @code{HL} as a base register, with an optional one-byte offset. | |
3336 | @item Whb | |
3337 | A memory reference using @code{HL} as a base register, with @code{B} or @code{C} as the index register. | |
3338 | @item Whl | |
3339 | A memory reference using @code{HL} as a base register, without any offset. | |
3340 | @item Ws1 | |
3341 | A memory reference using @code{SP} as a base register, with an optional one-byte offset. | |
3342 | @item Y | |
3343 | Any memory reference to an address in the near address space. | |
3344 | @item A | |
3345 | The @code{AX} register. | |
3346 | @item B | |
3347 | The @code{BC} register. | |
3348 | @item D | |
3349 | The @code{DE} register. | |
3350 | @item R | |
3351 | @code{A} through @code{L} registers. | |
3352 | @item S | |
3353 | The @code{SP} register. | |
3354 | @item T | |
3355 | The @code{HL} register. | |
3356 | @item Z08W | |
3357 | The 16-bit @code{R8} register. | |
3358 | @item Z10W | |
3359 | The 16-bit @code{R10} register. | |
3360 | @item Zint | |
3361 | The registers reserved for interrupts (@code{R24} to @code{R31}). | |
3362 | @item a | |
3363 | The @code{A} register. | |
3364 | @item b | |
3365 | The @code{B} register. | |
3366 | @item c | |
3367 | The @code{C} register. | |
3368 | @item d | |
3369 | The @code{D} register. | |
3370 | @item e | |
3371 | The @code{E} register. | |
3372 | @item h | |
3373 | The @code{H} register. | |
3374 | @item l | |
3375 | The @code{L} register. | |
3376 | @item v | |
3377 | The virtual registers. | |
3378 | @item w | |
3379 | The @code{PSW} register. | |
3380 | @item x | |
3381 | The @code{X} register. | |
3382 | ||
3383 | @end table | |
09cae750 PD |
3384 | |
3385 | @item RISC-V---@file{config/riscv/constraints.md} | |
3386 | @table @code | |
3387 | ||
3388 | @item f | |
3389 | A floating-point register (if availiable). | |
3390 | ||
3391 | @item I | |
3392 | An I-type 12-bit signed immediate. | |
3393 | ||
3394 | @item J | |
3395 | Integer zero. | |
3396 | ||
3397 | @item K | |
3398 | A 5-bit unsigned immediate for CSR access instructions. | |
3399 | ||
3400 | @item A | |
3401 | An address that is held in a general-purpose register. | |
3402 | ||
3403 | @end table | |
85b8555e | 3404 | |
65a324b4 NC |
3405 | @item RX---@file{config/rx/constraints.md} |
3406 | @table @code | |
3407 | @item Q | |
3408 | An address which does not involve register indirect addressing or | |
3409 | pre/post increment/decrement addressing. | |
3410 | ||
3411 | @item Symbol | |
3412 | A symbol reference. | |
3413 | ||
3414 | @item Int08 | |
3415 | A constant in the range @minus{}256 to 255, inclusive. | |
3416 | ||
3417 | @item Sint08 | |
3418 | A constant in the range @minus{}128 to 127, inclusive. | |
3419 | ||
3420 | @item Sint16 | |
3421 | A constant in the range @minus{}32768 to 32767, inclusive. | |
3422 | ||
3423 | @item Sint24 | |
3424 | A constant in the range @minus{}8388608 to 8388607, inclusive. | |
3425 | ||
3426 | @item Uint04 | |
3427 | A constant in the range 0 to 15, inclusive. | |
3428 | ||
3429 | @end table | |
3430 | ||
b4fbcb1b SL |
3431 | @item S/390 and zSeries---@file{config/s390/s390.h} |
3432 | @table @code | |
3433 | @item a | |
3434 | Address register (general purpose register except r0) | |
3435 | ||
3436 | @item c | |
3437 | Condition code register | |
3438 | ||
3439 | @item d | |
3440 | Data register (arbitrary general purpose register) | |
3441 | ||
3442 | @item f | |
3443 | Floating-point register | |
3444 | ||
3445 | @item I | |
3446 | Unsigned 8-bit constant (0--255) | |
3447 | ||
3448 | @item J | |
3449 | Unsigned 12-bit constant (0--4095) | |
3450 | ||
3451 | @item K | |
3452 | Signed 16-bit constant (@minus{}32768--32767) | |
3453 | ||
3454 | @item L | |
3455 | Value appropriate as displacement. | |
3456 | @table @code | |
3457 | @item (0..4095) | |
3458 | for short displacement | |
3459 | @item (@minus{}524288..524287) | |
3460 | for long displacement | |
3461 | @end table | |
3462 | ||
3463 | @item M | |
3464 | Constant integer with a value of 0x7fffffff. | |
3465 | ||
3466 | @item N | |
3467 | Multiple letter constraint followed by 4 parameter letters. | |
3468 | @table @code | |
3469 | @item 0..9: | |
3470 | number of the part counting from most to least significant | |
3471 | @item H,Q: | |
3472 | mode of the part | |
3473 | @item D,S,H: | |
3474 | mode of the containing operand | |
3475 | @item 0,F: | |
3476 | value of the other parts (F---all bits set) | |
3477 | @end table | |
3478 | The constraint matches if the specified part of a constant | |
3479 | has a value different from its other parts. | |
3480 | ||
3481 | @item Q | |
3482 | Memory reference without index register and with short displacement. | |
3483 | ||
3484 | @item R | |
3485 | Memory reference with index register and short displacement. | |
3486 | ||
3487 | @item S | |
3488 | Memory reference without index register but with long displacement. | |
3489 | ||
3490 | @item T | |
3491 | Memory reference with index register and long displacement. | |
3492 | ||
3493 | @item U | |
3494 | Pointer with short displacement. | |
3495 | ||
3496 | @item W | |
3497 | Pointer with long displacement. | |
3498 | ||
3499 | @item Y | |
3500 | Shift count operand. | |
3501 | ||
3502 | @end table | |
3503 | ||
03dda8e3 | 3504 | @need 1000 |
74fe790b | 3505 | @item SPARC---@file{config/sparc/sparc.h} |
03dda8e3 RK |
3506 | @table @code |
3507 | @item f | |
53e5f173 EB |
3508 | Floating-point register on the SPARC-V8 architecture and |
3509 | lower floating-point register on the SPARC-V9 architecture. | |
03dda8e3 RK |
3510 | |
3511 | @item e | |
8a36672b | 3512 | Floating-point register. It is equivalent to @samp{f} on the |
53e5f173 EB |
3513 | SPARC-V8 architecture and contains both lower and upper |
3514 | floating-point registers on the SPARC-V9 architecture. | |
03dda8e3 | 3515 | |
8a69f99f EB |
3516 | @item c |
3517 | Floating-point condition code register. | |
3518 | ||
3519 | @item d | |
8a36672b | 3520 | Lower floating-point register. It is only valid on the SPARC-V9 |
53e5f173 | 3521 | architecture when the Visual Instruction Set is available. |
8a69f99f EB |
3522 | |
3523 | @item b | |
8a36672b | 3524 | Floating-point register. It is only valid on the SPARC-V9 architecture |
53e5f173 | 3525 | when the Visual Instruction Set is available. |
8a69f99f EB |
3526 | |
3527 | @item h | |
3528 | 64-bit global or out register for the SPARC-V8+ architecture. | |
3529 | ||
923f9ded DM |
3530 | @item C |
3531 | The constant all-ones, for floating-point. | |
3532 | ||
8b98b5fd DM |
3533 | @item A |
3534 | Signed 5-bit constant | |
3535 | ||
66e62b49 KH |
3536 | @item D |
3537 | A vector constant | |
3538 | ||
03dda8e3 | 3539 | @item I |
1e5f973d | 3540 | Signed 13-bit constant |
03dda8e3 RK |
3541 | |
3542 | @item J | |
3543 | Zero | |
3544 | ||
3545 | @item K | |
1e5f973d | 3546 | 32-bit constant with the low 12 bits clear (a constant that can be |
03dda8e3 RK |
3547 | loaded with the @code{sethi} instruction) |
3548 | ||
7d6040e8 | 3549 | @item L |
923f9ded DM |
3550 | A constant in the range supported by @code{movcc} instructions (11-bit |
3551 | signed immediate) | |
7d6040e8 AO |
3552 | |
3553 | @item M | |
923f9ded DM |
3554 | A constant in the range supported by @code{movrcc} instructions (10-bit |
3555 | signed immediate) | |
7d6040e8 AO |
3556 | |
3557 | @item N | |
3558 | Same as @samp{K}, except that it verifies that bits that are not in the | |
57694e40 | 3559 | lower 32-bit range are all zero. Must be used instead of @samp{K} for |
7d6040e8 AO |
3560 | modes wider than @code{SImode} |
3561 | ||
ef0139b1 EB |
3562 | @item O |
3563 | The constant 4096 | |
3564 | ||
03dda8e3 RK |
3565 | @item G |
3566 | Floating-point zero | |
3567 | ||
3568 | @item H | |
1e5f973d | 3569 | Signed 13-bit constant, sign-extended to 32 or 64 bits |
03dda8e3 | 3570 | |
923f9ded DM |
3571 | @item P |
3572 | The constant -1 | |
3573 | ||
03dda8e3 | 3574 | @item Q |
62190128 DM |
3575 | Floating-point constant whose integral representation can |
3576 | be moved into an integer register using a single sethi | |
3577 | instruction | |
3578 | ||
3579 | @item R | |
3580 | Floating-point constant whose integral representation can | |
3581 | be moved into an integer register using a single mov | |
3582 | instruction | |
03dda8e3 RK |
3583 | |
3584 | @item S | |
62190128 DM |
3585 | Floating-point constant whose integral representation can |
3586 | be moved into an integer register using a high/lo_sum | |
3587 | instruction sequence | |
03dda8e3 RK |
3588 | |
3589 | @item T | |
3590 | Memory address aligned to an 8-byte boundary | |
3591 | ||
aaa050aa DM |
3592 | @item U |
3593 | Even register | |
3594 | ||
7a31a340 | 3595 | @item W |
c75d6010 JM |
3596 | Memory address for @samp{e} constraint registers |
3597 | ||
923f9ded DM |
3598 | @item w |
3599 | Memory address with only a base register | |
3600 | ||
c75d6010 JM |
3601 | @item Y |
3602 | Vector zero | |
7a31a340 | 3603 | |
6ca30df6 MH |
3604 | @end table |
3605 | ||
85d9c13c TS |
3606 | @item SPU---@file{config/spu/spu.h} |
3607 | @table @code | |
3608 | @item a | |
ff2ce160 | 3609 | An immediate which can be loaded with the il/ila/ilh/ilhu instructions. const_int is treated as a 64 bit value. |
85d9c13c TS |
3610 | |
3611 | @item c | |
ff2ce160 | 3612 | An immediate for and/xor/or instructions. const_int is treated as a 64 bit value. |
85d9c13c TS |
3613 | |
3614 | @item d | |
ff2ce160 | 3615 | An immediate for the @code{iohl} instruction. const_int is treated as a 64 bit value. |
85d9c13c TS |
3616 | |
3617 | @item f | |
ff2ce160 | 3618 | An immediate which can be loaded with @code{fsmbi}. |
85d9c13c TS |
3619 | |
3620 | @item A | |
ff2ce160 | 3621 | An immediate which can be loaded with the il/ila/ilh/ilhu instructions. const_int is treated as a 32 bit value. |
85d9c13c | 3622 | |
b4fbcb1b SL |
3623 | @item B |
3624 | An immediate for most arithmetic instructions. const_int is treated as a 32 bit value. | |
9f339dde | 3625 | |
b4fbcb1b SL |
3626 | @item C |
3627 | An immediate for and/xor/or instructions. const_int is treated as a 32 bit value. | |
9f339dde | 3628 | |
b4fbcb1b SL |
3629 | @item D |
3630 | An immediate for the @code{iohl} instruction. const_int is treated as a 32 bit value. | |
9f339dde GK |
3631 | |
3632 | @item I | |
b4fbcb1b | 3633 | A constant in the range [@minus{}64, 63] for shift/rotate instructions. |
9f339dde GK |
3634 | |
3635 | @item J | |
b4fbcb1b | 3636 | An unsigned 7-bit constant for conversion/nop/channel instructions. |
9f339dde GK |
3637 | |
3638 | @item K | |
b4fbcb1b | 3639 | A signed 10-bit constant for most arithmetic instructions. |
9f339dde GK |
3640 | |
3641 | @item M | |
b4fbcb1b | 3642 | A signed 16 bit immediate for @code{stop}. |
9f339dde GK |
3643 | |
3644 | @item N | |
b4fbcb1b | 3645 | An unsigned 16-bit constant for @code{iohl} and @code{fsmbi}. |
9f339dde GK |
3646 | |
3647 | @item O | |
b4fbcb1b | 3648 | An unsigned 7-bit constant whose 3 least significant bits are 0. |
9f339dde GK |
3649 | |
3650 | @item P | |
b4fbcb1b | 3651 | An unsigned 3-bit constant for 16-byte rotates and shifts |
9f339dde GK |
3652 | |
3653 | @item R | |
b4fbcb1b | 3654 | Call operand, reg, for indirect calls |
9f339dde GK |
3655 | |
3656 | @item S | |
b4fbcb1b | 3657 | Call operand, symbol, for relative calls. |
9f339dde GK |
3658 | |
3659 | @item T | |
b4fbcb1b | 3660 | Call operand, const_int, for absolute calls. |
9f339dde GK |
3661 | |
3662 | @item U | |
b4fbcb1b SL |
3663 | An immediate which can be loaded with the il/ila/ilh/ilhu instructions. const_int is sign extended to 128 bit. |
3664 | ||
3665 | @item W | |
3666 | An immediate for shift and rotate instructions. const_int is treated as a 32 bit value. | |
3667 | ||
3668 | @item Y | |
3669 | An immediate for and/xor/or instructions. const_int is sign extended as a 128 bit. | |
9f339dde | 3670 | |
e2ce66a9 | 3671 | @item Z |
b4fbcb1b | 3672 | An immediate for the @code{iohl} instruction. const_int is sign extended to 128 bit. |
e2ce66a9 | 3673 | |
9f339dde GK |
3674 | @end table |
3675 | ||
bcead286 BS |
3676 | @item TI C6X family---@file{config/c6x/constraints.md} |
3677 | @table @code | |
3678 | @item a | |
3679 | Register file A (A0--A31). | |
3680 | ||
3681 | @item b | |
3682 | Register file B (B0--B31). | |
3683 | ||
3684 | @item A | |
3685 | Predicate registers in register file A (A0--A2 on C64X and | |
3686 | higher, A1 and A2 otherwise). | |
3687 | ||
3688 | @item B | |
3689 | Predicate registers in register file B (B0--B2). | |
3690 | ||
3691 | @item C | |
3692 | A call-used register in register file B (B0--B9, B16--B31). | |
3693 | ||
3694 | @item Da | |
3695 | Register file A, excluding predicate registers (A3--A31, | |
3696 | plus A0 if not C64X or higher). | |
3697 | ||
3698 | @item Db | |
3699 | Register file B, excluding predicate registers (B3--B31). | |
3700 | ||
3701 | @item Iu4 | |
3702 | Integer constant in the range 0 @dots{} 15. | |
3703 | ||
3704 | @item Iu5 | |
3705 | Integer constant in the range 0 @dots{} 31. | |
3706 | ||
3707 | @item In5 | |
3708 | Integer constant in the range @minus{}31 @dots{} 0. | |
3709 | ||
3710 | @item Is5 | |
3711 | Integer constant in the range @minus{}16 @dots{} 15. | |
3712 | ||
3713 | @item I5x | |
3714 | Integer constant that can be the operand of an ADDA or a SUBA insn. | |
3715 | ||
3716 | @item IuB | |
3717 | Integer constant in the range 0 @dots{} 65535. | |
3718 | ||
3719 | @item IsB | |
3720 | Integer constant in the range @minus{}32768 @dots{} 32767. | |
3721 | ||
3722 | @item IsC | |
3723 | Integer constant in the range @math{-2^{20}} @dots{} @math{2^{20} - 1}. | |
3724 | ||
3725 | @item Jc | |
3726 | Integer constant that is a valid mask for the clr instruction. | |
3727 | ||
3728 | @item Js | |
3729 | Integer constant that is a valid mask for the set instruction. | |
3730 | ||
3731 | @item Q | |
3732 | Memory location with A base register. | |
3733 | ||
3734 | @item R | |
3735 | Memory location with B base register. | |
3736 | ||
3737 | @ifset INTERNALS | |
3738 | @item S0 | |
3739 | On C64x+ targets, a GP-relative small data reference. | |
3740 | ||
3741 | @item S1 | |
3742 | Any kind of @code{SYMBOL_REF}, for use in a call address. | |
3743 | ||
3744 | @item Si | |
3745 | Any kind of immediate operand, unless it matches the S0 constraint. | |
3746 | ||
3747 | @item T | |
3748 | Memory location with B base register, but not using a long offset. | |
3749 | ||
3750 | @item W | |
fd250f0d | 3751 | A memory operand with an address that cannot be used in an unaligned access. |
bcead286 BS |
3752 | |
3753 | @end ifset | |
3754 | @item Z | |
3755 | Register B14 (aka DP). | |
3756 | ||
3757 | @end table | |
3758 | ||
dd552284 WL |
3759 | @item TILE-Gx---@file{config/tilegx/constraints.md} |
3760 | @table @code | |
3761 | @item R00 | |
3762 | @itemx R01 | |
3763 | @itemx R02 | |
3764 | @itemx R03 | |
3765 | @itemx R04 | |
3766 | @itemx R05 | |
3767 | @itemx R06 | |
3768 | @itemx R07 | |
3769 | @itemx R08 | |
3770 | @itemx R09 | |
655c5444 | 3771 | @itemx R10 |
dd552284 WL |
3772 | Each of these represents a register constraint for an individual |
3773 | register, from r0 to r10. | |
3774 | ||
3775 | @item I | |
3776 | Signed 8-bit integer constant. | |
3777 | ||
3778 | @item J | |
3779 | Signed 16-bit integer constant. | |
3780 | ||
3781 | @item K | |
3782 | Unsigned 16-bit integer constant. | |
3783 | ||
3784 | @item L | |
3785 | Integer constant that fits in one signed byte when incremented by one | |
3786 | (@minus{}129 @dots{} 126). | |
3787 | ||
3788 | @item m | |
3789 | Memory operand. If used together with @samp{<} or @samp{>}, the | |
3790 | operand can have postincrement which requires printing with @samp{%In} | |
3791 | and @samp{%in} on TILE-Gx. For example: | |
3792 | ||
3793 | @smallexample | |
3794 | asm ("st_add %I0,%1,%i0" : "=m<>" (*mem) : "r" (val)); | |
3795 | @end smallexample | |
3796 | ||
3797 | @item M | |
3798 | A bit mask suitable for the BFINS instruction. | |
3799 | ||
3800 | @item N | |
3801 | Integer constant that is a byte tiled out eight times. | |
3802 | ||
3803 | @item O | |
3804 | The integer zero constant. | |
3805 | ||
3806 | @item P | |
3807 | Integer constant that is a sign-extended byte tiled out as four shorts. | |
3808 | ||
3809 | @item Q | |
3810 | Integer constant that fits in one signed byte when incremented | |
3811 | (@minus{}129 @dots{} 126), but excluding -1. | |
3812 | ||
3813 | @item S | |
3814 | Integer constant that has all 1 bits consecutive and starting at bit 0. | |
3815 | ||
3816 | @item T | |
3817 | A 16-bit fragment of a got, tls, or pc-relative reference. | |
3818 | ||
3819 | @item U | |
3820 | Memory operand except postincrement. This is roughly the same as | |
3821 | @samp{m} when not used together with @samp{<} or @samp{>}. | |
3822 | ||
3823 | @item W | |
3824 | An 8-element vector constant with identical elements. | |
3825 | ||
3826 | @item Y | |
3827 | A 4-element vector constant with identical elements. | |
3828 | ||
3829 | @item Z0 | |
3830 | The integer constant 0xffffffff. | |
3831 | ||
3832 | @item Z1 | |
3833 | The integer constant 0xffffffff00000000. | |
3834 | ||
3835 | @end table | |
3836 | ||
3837 | @item TILEPro---@file{config/tilepro/constraints.md} | |
3838 | @table @code | |
3839 | @item R00 | |
3840 | @itemx R01 | |
3841 | @itemx R02 | |
3842 | @itemx R03 | |
3843 | @itemx R04 | |
3844 | @itemx R05 | |
3845 | @itemx R06 | |
3846 | @itemx R07 | |
3847 | @itemx R08 | |
3848 | @itemx R09 | |
655c5444 | 3849 | @itemx R10 |
dd552284 WL |
3850 | Each of these represents a register constraint for an individual |
3851 | register, from r0 to r10. | |
3852 | ||
3853 | @item I | |
3854 | Signed 8-bit integer constant. | |
3855 | ||
3856 | @item J | |
3857 | Signed 16-bit integer constant. | |
3858 | ||
3859 | @item K | |
3860 | Nonzero integer constant with low 16 bits zero. | |
3861 | ||
3862 | @item L | |
3863 | Integer constant that fits in one signed byte when incremented by one | |
3864 | (@minus{}129 @dots{} 126). | |
3865 | ||
3866 | @item m | |
3867 | Memory operand. If used together with @samp{<} or @samp{>}, the | |
3868 | operand can have postincrement which requires printing with @samp{%In} | |
3869 | and @samp{%in} on TILEPro. For example: | |
3870 | ||
3871 | @smallexample | |
3872 | asm ("swadd %I0,%1,%i0" : "=m<>" (mem) : "r" (val)); | |
3873 | @end smallexample | |
3874 | ||
3875 | @item M | |
3876 | A bit mask suitable for the MM instruction. | |
3877 | ||
3878 | @item N | |
3879 | Integer constant that is a byte tiled out four times. | |
3880 | ||
3881 | @item O | |
3882 | The integer zero constant. | |
3883 | ||
3884 | @item P | |
3885 | Integer constant that is a sign-extended byte tiled out as two shorts. | |
3886 | ||
3887 | @item Q | |
3888 | Integer constant that fits in one signed byte when incremented | |
3889 | (@minus{}129 @dots{} 126), but excluding -1. | |
3890 | ||
3891 | @item T | |
3892 | A symbolic operand, or a 16-bit fragment of a got, tls, or pc-relative | |
3893 | reference. | |
3894 | ||
3895 | @item U | |
3896 | Memory operand except postincrement. This is roughly the same as | |
3897 | @samp{m} when not used together with @samp{<} or @samp{>}. | |
3898 | ||
3899 | @item W | |
3900 | A 4-element vector constant with identical elements. | |
3901 | ||
3902 | @item Y | |
3903 | A 2-element vector constant with identical elements. | |
3904 | ||
3905 | @end table | |
3906 | ||
0969ec7d EB |
3907 | @item Visium---@file{config/visium/constraints.md} |
3908 | @table @code | |
3909 | @item b | |
3910 | EAM register @code{mdb} | |
3911 | ||
3912 | @item c | |
3913 | EAM register @code{mdc} | |
3914 | ||
3915 | @item f | |
3916 | Floating point register | |
3917 | ||
3918 | @ifset INTERNALS | |
3919 | @item k | |
3920 | Register for sibcall optimization | |
3921 | @end ifset | |
3922 | ||
3923 | @item l | |
3924 | General register, but not @code{r29}, @code{r30} and @code{r31} | |
3925 | ||
3926 | @item t | |
3927 | Register @code{r1} | |
3928 | ||
3929 | @item u | |
3930 | Register @code{r2} | |
3931 | ||
3932 | @item v | |
3933 | Register @code{r3} | |
3934 | ||
3935 | @item G | |
3936 | Floating-point constant 0.0 | |
3937 | ||
3938 | @item J | |
3939 | Integer constant in the range 0 .. 65535 (16-bit immediate) | |
3940 | ||
3941 | @item K | |
3942 | Integer constant in the range 1 .. 31 (5-bit immediate) | |
3943 | ||
3944 | @item L | |
3945 | Integer constant in the range @minus{}65535 .. @minus{}1 (16-bit negative immediate) | |
3946 | ||
3947 | @item M | |
3948 | Integer constant @minus{}1 | |
3949 | ||
3950 | @item O | |
3951 | Integer constant 0 | |
3952 | ||
3953 | @item P | |
3954 | Integer constant 32 | |
3955 | @end table | |
3956 | ||
b4fbcb1b SL |
3957 | @item x86 family---@file{config/i386/constraints.md} |
3958 | @table @code | |
3959 | @item R | |
3960 | Legacy register---the eight integer registers available on all | |
3961 | i386 processors (@code{a}, @code{b}, @code{c}, @code{d}, | |
3962 | @code{si}, @code{di}, @code{bp}, @code{sp}). | |
3963 | ||
3964 | @item q | |
3965 | Any register accessible as @code{@var{r}l}. In 32-bit mode, @code{a}, | |
3966 | @code{b}, @code{c}, and @code{d}; in 64-bit mode, any integer register. | |
3967 | ||
3968 | @item Q | |
3969 | Any register accessible as @code{@var{r}h}: @code{a}, @code{b}, | |
3970 | @code{c}, and @code{d}. | |
3971 | ||
3972 | @ifset INTERNALS | |
3973 | @item l | |
3974 | Any register that can be used as the index in a base+index memory | |
3975 | access: that is, any general register except the stack pointer. | |
3976 | @end ifset | |
3977 | ||
3978 | @item a | |
3979 | The @code{a} register. | |
3980 | ||
3981 | @item b | |
3982 | The @code{b} register. | |
3983 | ||
3984 | @item c | |
3985 | The @code{c} register. | |
3986 | ||
3987 | @item d | |
3988 | The @code{d} register. | |
3989 | ||
3990 | @item S | |
3991 | The @code{si} register. | |
3992 | ||
3993 | @item D | |
3994 | The @code{di} register. | |
3995 | ||
3996 | @item A | |
3997 | The @code{a} and @code{d} registers. This class is used for instructions | |
3998 | that return double word results in the @code{ax:dx} register pair. Single | |
3999 | word values will be allocated either in @code{ax} or @code{dx}. | |
4000 | For example on i386 the following implements @code{rdtsc}: | |
4001 | ||
4002 | @smallexample | |
4003 | unsigned long long rdtsc (void) | |
4004 | @{ | |
4005 | unsigned long long tick; | |
4006 | __asm__ __volatile__("rdtsc":"=A"(tick)); | |
4007 | return tick; | |
4008 | @} | |
4009 | @end smallexample | |
4010 | ||
4011 | This is not correct on x86-64 as it would allocate tick in either @code{ax} | |
4012 | or @code{dx}. You have to use the following variant instead: | |
4013 | ||
4014 | @smallexample | |
4015 | unsigned long long rdtsc (void) | |
4016 | @{ | |
4017 | unsigned int tickl, tickh; | |
4018 | __asm__ __volatile__("rdtsc":"=a"(tickl),"=d"(tickh)); | |
4019 | return ((unsigned long long)tickh << 32)|tickl; | |
4020 | @} | |
4021 | @end smallexample | |
4022 | ||
de3fb1a6 SP |
4023 | @item U |
4024 | The call-clobbered integer registers. | |
b4fbcb1b SL |
4025 | |
4026 | @item f | |
4027 | Any 80387 floating-point (stack) register. | |
4028 | ||
4029 | @item t | |
4030 | Top of 80387 floating-point stack (@code{%st(0)}). | |
4031 | ||
4032 | @item u | |
4033 | Second from top of 80387 floating-point stack (@code{%st(1)}). | |
4034 | ||
de3fb1a6 SP |
4035 | @ifset INTERNALS |
4036 | @item Yk | |
4037 | Any mask register that can be used as a predicate, i.e. @code{k1-k7}. | |
4038 | ||
4039 | @item k | |
4040 | Any mask register. | |
4041 | @end ifset | |
4042 | ||
b4fbcb1b SL |
4043 | @item y |
4044 | Any MMX register. | |
4045 | ||
4046 | @item x | |
4047 | Any SSE register. | |
4048 | ||
de3fb1a6 SP |
4049 | @item v |
4050 | Any EVEX encodable SSE register (@code{%xmm0-%xmm31}). | |
4051 | ||
4052 | @ifset INTERNALS | |
4053 | @item w | |
4054 | Any bound register. | |
4055 | @end ifset | |
4056 | ||
b4fbcb1b SL |
4057 | @item Yz |
4058 | First SSE register (@code{%xmm0}). | |
4059 | ||
4060 | @ifset INTERNALS | |
b4fbcb1b SL |
4061 | @item Yi |
4062 | Any SSE register, when SSE2 and inter-unit moves are enabled. | |
4063 | ||
de3fb1a6 SP |
4064 | @item Yj |
4065 | Any SSE register, when SSE2 and inter-unit moves from vector registers are enabled. | |
4066 | ||
b4fbcb1b SL |
4067 | @item Ym |
4068 | Any MMX register, when inter-unit moves are enabled. | |
de3fb1a6 SP |
4069 | |
4070 | @item Yn | |
4071 | Any MMX register, when inter-unit moves from vector registers are enabled. | |
4072 | ||
4073 | @item Yp | |
4074 | Any integer register when @code{TARGET_PARTIAL_REG_STALL} is disabled. | |
4075 | ||
4076 | @item Ya | |
4077 | Any integer register when zero extensions with @code{AND} are disabled. | |
4078 | ||
4079 | @item Yb | |
4080 | Any register that can be used as the GOT base when calling@* | |
4081 | @code{___tls_get_addr}: that is, any general register except @code{a} | |
4082 | and @code{sp} registers, for @option{-fno-plt} if linker supports it. | |
4083 | Otherwise, @code{b} register. | |
4084 | ||
4085 | @item Yf | |
4086 | Any x87 register when 80387 floating-point arithmetic is enabled. | |
4087 | ||
4088 | @item Yr | |
4089 | Lower SSE register when avoiding REX prefix and all SSE registers otherwise. | |
4090 | ||
4091 | @item Yv | |
4092 | For AVX512VL, any EVEX-encodable SSE register (@code{%xmm0-%xmm31}), | |
4093 | otherwise any SSE register. | |
4094 | ||
4095 | @item Yh | |
4096 | Any EVEX-encodable SSE register, that has number factor of four. | |
4097 | ||
4098 | @item Bf | |
4099 | Flags register operand. | |
4100 | ||
4101 | @item Bg | |
4102 | GOT memory operand. | |
4103 | ||
4104 | @item Bm | |
4105 | Vector memory operand. | |
4106 | ||
4107 | @item Bc | |
4108 | Constant memory operand. | |
4109 | ||
4110 | @item Bn | |
4111 | Memory operand without REX prefix. | |
4112 | ||
4113 | @item Bs | |
4114 | Sibcall memory operand. | |
4115 | ||
4116 | @item Bw | |
4117 | Call memory operand. | |
4118 | ||
4119 | @item Bz | |
4120 | Constant call address operand. | |
4121 | ||
4122 | @item BC | |
4123 | SSE constant -1 operand. | |
b4fbcb1b SL |
4124 | @end ifset |
4125 | ||
4126 | @item I | |
4127 | Integer constant in the range 0 @dots{} 31, for 32-bit shifts. | |
4128 | ||
4129 | @item J | |
4130 | Integer constant in the range 0 @dots{} 63, for 64-bit shifts. | |
4131 | ||
4132 | @item K | |
4133 | Signed 8-bit integer constant. | |
4134 | ||
4135 | @item L | |
4136 | @code{0xFF} or @code{0xFFFF}, for andsi as a zero-extending move. | |
4137 | ||
4138 | @item M | |
4139 | 0, 1, 2, or 3 (shifts for the @code{lea} instruction). | |
4140 | ||
4141 | @item N | |
4142 | Unsigned 8-bit integer constant (for @code{in} and @code{out} | |
4143 | instructions). | |
4144 | ||
4145 | @ifset INTERNALS | |
4146 | @item O | |
4147 | Integer constant in the range 0 @dots{} 127, for 128-bit shifts. | |
4148 | @end ifset | |
4149 | ||
4150 | @item G | |
4151 | Standard 80387 floating point constant. | |
4152 | ||
4153 | @item C | |
aec0b19e | 4154 | SSE constant zero operand. |
b4fbcb1b SL |
4155 | |
4156 | @item e | |
4157 | 32-bit signed integer constant, or a symbolic reference known | |
4158 | to fit that range (for immediate operands in sign-extending x86-64 | |
4159 | instructions). | |
4160 | ||
de3fb1a6 SP |
4161 | @item We |
4162 | 32-bit signed integer constant, or a symbolic reference known | |
4163 | to fit that range (for sign-extending conversion operations that | |
4164 | require non-@code{VOIDmode} immediate operands). | |
4165 | ||
4166 | @item Wz | |
4167 | 32-bit unsigned integer constant, or a symbolic reference known | |
4168 | to fit that range (for zero-extending conversion operations that | |
4169 | require non-@code{VOIDmode} immediate operands). | |
4170 | ||
4171 | @item Wd | |
4172 | 128-bit integer constant where both the high and low 64-bit word | |
4173 | satisfy the @code{e} constraint. | |
4174 | ||
b4fbcb1b SL |
4175 | @item Z |
4176 | 32-bit unsigned integer constant, or a symbolic reference known | |
4177 | to fit that range (for immediate operands in zero-extending x86-64 | |
4178 | instructions). | |
4179 | ||
de3fb1a6 SP |
4180 | @item Tv |
4181 | VSIB address operand. | |
4182 | ||
4183 | @item Ts | |
4184 | Address operand without segment register. | |
4185 | ||
4186 | @item Ti | |
4187 | MPX address operand without index. | |
4188 | ||
4189 | @item Tb | |
4190 | MPX address operand without base. | |
4191 | ||
b4fbcb1b SL |
4192 | @end table |
4193 | ||
4194 | @item Xstormy16---@file{config/stormy16/stormy16.h} | |
4195 | @table @code | |
4196 | @item a | |
4197 | Register r0. | |
4198 | ||
4199 | @item b | |
4200 | Register r1. | |
4201 | ||
4202 | @item c | |
4203 | Register r2. | |
4204 | ||
4205 | @item d | |
4206 | Register r8. | |
4207 | ||
4208 | @item e | |
4209 | Registers r0 through r7. | |
4210 | ||
4211 | @item t | |
4212 | Registers r0 and r1. | |
4213 | ||
4214 | @item y | |
4215 | The carry register. | |
4216 | ||
4217 | @item z | |
4218 | Registers r8 and r9. | |
4219 | ||
4220 | @item I | |
4221 | A constant between 0 and 3 inclusive. | |
4222 | ||
4223 | @item J | |
4224 | A constant that has exactly one bit set. | |
4225 | ||
4226 | @item K | |
4227 | A constant that has exactly one bit clear. | |
4228 | ||
4229 | @item L | |
4230 | A constant between 0 and 255 inclusive. | |
4231 | ||
4232 | @item M | |
4233 | A constant between @minus{}255 and 0 inclusive. | |
4234 | ||
4235 | @item N | |
4236 | A constant between @minus{}3 and 0 inclusive. | |
4237 | ||
4238 | @item O | |
4239 | A constant between 1 and 4 inclusive. | |
4240 | ||
4241 | @item P | |
4242 | A constant between @minus{}4 and @minus{}1 inclusive. | |
4243 | ||
4244 | @item Q | |
4245 | A memory reference that is a stack push. | |
4246 | ||
4247 | @item R | |
4248 | A memory reference that is a stack pop. | |
4249 | ||
4250 | @item S | |
4251 | A memory reference that refers to a constant address of known value. | |
4252 | ||
4253 | @item T | |
4254 | The register indicated by Rx (not implemented yet). | |
4255 | ||
4256 | @item U | |
4257 | A constant that is not between 2 and 15 inclusive. | |
4258 | ||
4259 | @item Z | |
4260 | The constant 0. | |
4261 | ||
4262 | @end table | |
4263 | ||
887af464 | 4264 | @item Xtensa---@file{config/xtensa/constraints.md} |
03984308 BW |
4265 | @table @code |
4266 | @item a | |
4267 | General-purpose 32-bit register | |
4268 | ||
4269 | @item b | |
4270 | One-bit boolean register | |
4271 | ||
4272 | @item A | |
4273 | MAC16 40-bit accumulator register | |
4274 | ||
4275 | @item I | |
4276 | Signed 12-bit integer constant, for use in MOVI instructions | |
4277 | ||
4278 | @item J | |
4279 | Signed 8-bit integer constant, for use in ADDI instructions | |
4280 | ||
4281 | @item K | |
4282 | Integer constant valid for BccI instructions | |
4283 | ||
4284 | @item L | |
4285 | Unsigned constant valid for BccUI instructions | |
4286 | ||
4287 | @end table | |
4288 | ||
03dda8e3 RK |
4289 | @end table |
4290 | ||
7ac28727 AK |
4291 | @ifset INTERNALS |
4292 | @node Disable Insn Alternatives | |
4293 | @subsection Disable insn alternatives using the @code{enabled} attribute | |
4294 | @cindex enabled | |
4295 | ||
9840b2fa RS |
4296 | There are three insn attributes that may be used to selectively disable |
4297 | instruction alternatives: | |
7ac28727 | 4298 | |
9840b2fa RS |
4299 | @table @code |
4300 | @item enabled | |
4301 | Says whether an alternative is available on the current subtarget. | |
7ac28727 | 4302 | |
9840b2fa RS |
4303 | @item preferred_for_size |
4304 | Says whether an enabled alternative should be used in code that is | |
4305 | optimized for size. | |
7ac28727 | 4306 | |
9840b2fa RS |
4307 | @item preferred_for_speed |
4308 | Says whether an enabled alternative should be used in code that is | |
4309 | optimized for speed. | |
4310 | @end table | |
4311 | ||
4312 | All these attributes should use @code{(const_int 1)} to allow an alternative | |
4313 | or @code{(const_int 0)} to disallow it. The attributes must be a static | |
4314 | property of the subtarget; they cannot for example depend on the | |
4315 | current operands, on the current optimization level, on the location | |
4316 | of the insn within the body of a loop, on whether register allocation | |
4317 | has finished, or on the current compiler pass. | |
4318 | ||
4319 | The @code{enabled} attribute is a correctness property. It tells GCC to act | |
4320 | as though the disabled alternatives were never defined in the first place. | |
4321 | This is useful when adding new instructions to an existing pattern in | |
4322 | cases where the new instructions are only available for certain cpu | |
4323 | architecture levels (typically mapped to the @code{-march=} command-line | |
4324 | option). | |
4325 | ||
4326 | In contrast, the @code{preferred_for_size} and @code{preferred_for_speed} | |
4327 | attributes are strong optimization hints rather than correctness properties. | |
4328 | @code{preferred_for_size} tells GCC which alternatives to consider when | |
4329 | adding or modifying an instruction that GCC wants to optimize for size. | |
4330 | @code{preferred_for_speed} does the same thing for speed. Note that things | |
4331 | like code motion can lead to cases where code optimized for size uses | |
4332 | alternatives that are not preferred for size, and similarly for speed. | |
4333 | ||
4334 | Although @code{define_insn}s can in principle specify the @code{enabled} | |
4335 | attribute directly, it is often clearer to have subsiduary attributes | |
4336 | for each architectural feature of interest. The @code{define_insn}s | |
4337 | can then use these subsiduary attributes to say which alternatives | |
4338 | require which features. The example below does this for @code{cpu_facility}. | |
7ac28727 AK |
4339 | |
4340 | E.g. the following two patterns could easily be merged using the @code{enabled} | |
4341 | attribute: | |
4342 | ||
4343 | @smallexample | |
4344 | ||
4345 | (define_insn "*movdi_old" | |
4346 | [(set (match_operand:DI 0 "register_operand" "=d") | |
4347 | (match_operand:DI 1 "register_operand" " d"))] | |
4348 | "!TARGET_NEW" | |
4349 | "lgr %0,%1") | |
4350 | ||
4351 | (define_insn "*movdi_new" | |
4352 | [(set (match_operand:DI 0 "register_operand" "=d,f,d") | |
4353 | (match_operand:DI 1 "register_operand" " d,d,f"))] | |
4354 | "TARGET_NEW" | |
4355 | "@@ | |
4356 | lgr %0,%1 | |
4357 | ldgr %0,%1 | |
4358 | lgdr %0,%1") | |
4359 | ||
4360 | @end smallexample | |
4361 | ||
4362 | to: | |
4363 | ||
4364 | @smallexample | |
4365 | ||
4366 | (define_insn "*movdi_combined" | |
4367 | [(set (match_operand:DI 0 "register_operand" "=d,f,d") | |
4368 | (match_operand:DI 1 "register_operand" " d,d,f"))] | |
4369 | "" | |
4370 | "@@ | |
4371 | lgr %0,%1 | |
4372 | ldgr %0,%1 | |
4373 | lgdr %0,%1" | |
4374 | [(set_attr "cpu_facility" "*,new,new")]) | |
4375 | ||
4376 | @end smallexample | |
4377 | ||
4378 | with the @code{enabled} attribute defined like this: | |
4379 | ||
4380 | @smallexample | |
4381 | ||
4382 | (define_attr "cpu_facility" "standard,new" (const_string "standard")) | |
4383 | ||
4384 | (define_attr "enabled" "" | |
4385 | (cond [(eq_attr "cpu_facility" "standard") (const_int 1) | |
4386 | (and (eq_attr "cpu_facility" "new") | |
4387 | (ne (symbol_ref "TARGET_NEW") (const_int 0))) | |
4388 | (const_int 1)] | |
4389 | (const_int 0))) | |
4390 | ||
4391 | @end smallexample | |
4392 | ||
4393 | @end ifset | |
4394 | ||
03dda8e3 | 4395 | @ifset INTERNALS |
f38840db ZW |
4396 | @node Define Constraints |
4397 | @subsection Defining Machine-Specific Constraints | |
4398 | @cindex defining constraints | |
4399 | @cindex constraints, defining | |
4400 | ||
4401 | Machine-specific constraints fall into two categories: register and | |
4402 | non-register constraints. Within the latter category, constraints | |
4403 | which allow subsets of all possible memory or address operands should | |
4404 | be specially marked, to give @code{reload} more information. | |
4405 | ||
4406 | Machine-specific constraints can be given names of arbitrary length, | |
4407 | but they must be entirely composed of letters, digits, underscores | |
4408 | (@samp{_}), and angle brackets (@samp{< >}). Like C identifiers, they | |
ff2ce160 | 4409 | must begin with a letter or underscore. |
f38840db ZW |
4410 | |
4411 | In order to avoid ambiguity in operand constraint strings, no | |
4412 | constraint can have a name that begins with any other constraint's | |
4413 | name. For example, if @code{x} is defined as a constraint name, | |
4414 | @code{xy} may not be, and vice versa. As a consequence of this rule, | |
4415 | no constraint may begin with one of the generic constraint letters: | |
4416 | @samp{E F V X g i m n o p r s}. | |
4417 | ||
4418 | Register constraints correspond directly to register classes. | |
4419 | @xref{Register Classes}. There is thus not much flexibility in their | |
4420 | definitions. | |
4421 | ||
4422 | @deffn {MD Expression} define_register_constraint name regclass docstring | |
4423 | All three arguments are string constants. | |
4424 | @var{name} is the name of the constraint, as it will appear in | |
5be527d0 RG |
4425 | @code{match_operand} expressions. If @var{name} is a multi-letter |
4426 | constraint its length shall be the same for all constraints starting | |
4427 | with the same letter. @var{regclass} can be either the | |
f38840db ZW |
4428 | name of the corresponding register class (@pxref{Register Classes}), |
4429 | or a C expression which evaluates to the appropriate register class. | |
4430 | If it is an expression, it must have no side effects, and it cannot | |
4431 | look at the operand. The usual use of expressions is to map some | |
4432 | register constraints to @code{NO_REGS} when the register class | |
4433 | is not available on a given subarchitecture. | |
4434 | ||
4435 | @var{docstring} is a sentence documenting the meaning of the | |
4436 | constraint. Docstrings are explained further below. | |
4437 | @end deffn | |
4438 | ||
4439 | Non-register constraints are more like predicates: the constraint | |
527a3750 | 4440 | definition gives a boolean expression which indicates whether the |
f38840db ZW |
4441 | constraint matches. |
4442 | ||
4443 | @deffn {MD Expression} define_constraint name docstring exp | |
4444 | The @var{name} and @var{docstring} arguments are the same as for | |
4445 | @code{define_register_constraint}, but note that the docstring comes | |
4446 | immediately after the name for these expressions. @var{exp} is an RTL | |
4447 | expression, obeying the same rules as the RTL expressions in predicate | |
4448 | definitions. @xref{Defining Predicates}, for details. If it | |
4449 | evaluates true, the constraint matches; if it evaluates false, it | |
4450 | doesn't. Constraint expressions should indicate which RTL codes they | |
4451 | might match, just like predicate expressions. | |
4452 | ||
4453 | @code{match_test} C expressions have access to the | |
4454 | following variables: | |
4455 | ||
4456 | @table @var | |
4457 | @item op | |
4458 | The RTL object defining the operand. | |
4459 | @item mode | |
4460 | The machine mode of @var{op}. | |
4461 | @item ival | |
4462 | @samp{INTVAL (@var{op})}, if @var{op} is a @code{const_int}. | |
4463 | @item hval | |
4464 | @samp{CONST_DOUBLE_HIGH (@var{op})}, if @var{op} is an integer | |
4465 | @code{const_double}. | |
4466 | @item lval | |
4467 | @samp{CONST_DOUBLE_LOW (@var{op})}, if @var{op} is an integer | |
4468 | @code{const_double}. | |
4469 | @item rval | |
4470 | @samp{CONST_DOUBLE_REAL_VALUE (@var{op})}, if @var{op} is a floating-point | |
3fa1b0e5 | 4471 | @code{const_double}. |
f38840db ZW |
4472 | @end table |
4473 | ||
4474 | The @var{*val} variables should only be used once another piece of the | |
4475 | expression has verified that @var{op} is the appropriate kind of RTL | |
4476 | object. | |
4477 | @end deffn | |
4478 | ||
4479 | Most non-register constraints should be defined with | |
4480 | @code{define_constraint}. The remaining two definition expressions | |
4481 | are only appropriate for constraints that should be handled specially | |
4482 | by @code{reload} if they fail to match. | |
4483 | ||
4484 | @deffn {MD Expression} define_memory_constraint name docstring exp | |
4485 | Use this expression for constraints that match a subset of all memory | |
4486 | operands: that is, @code{reload} can make them match by converting the | |
4487 | operand to the form @samp{@w{(mem (reg @var{X}))}}, where @var{X} is a | |
4488 | base register (from the register class specified by | |
4489 | @code{BASE_REG_CLASS}, @pxref{Register Classes}). | |
4490 | ||
4491 | For example, on the S/390, some instructions do not accept arbitrary | |
4492 | memory references, but only those that do not make use of an index | |
4493 | register. The constraint letter @samp{Q} is defined to represent a | |
4494 | memory address of this type. If @samp{Q} is defined with | |
4495 | @code{define_memory_constraint}, a @samp{Q} constraint can handle any | |
4496 | memory operand, because @code{reload} knows it can simply copy the | |
4497 | memory address into a base register if required. This is analogous to | |
e4ae5e77 | 4498 | the way an @samp{o} constraint can handle any memory operand. |
f38840db ZW |
4499 | |
4500 | The syntax and semantics are otherwise identical to | |
4501 | @code{define_constraint}. | |
4502 | @end deffn | |
4503 | ||
9eb1ca69 VM |
4504 | @deffn {MD Expression} define_special_memory_constraint name docstring exp |
4505 | Use this expression for constraints that match a subset of all memory | |
4506 | operands: that is, @code{reload} can not make them match by reloading | |
4507 | the address as it is described for @code{define_memory_constraint} or | |
4508 | such address reload is undesirable with the performance point of view. | |
4509 | ||
4510 | For example, @code{define_special_memory_constraint} can be useful if | |
4511 | specifically aligned memory is necessary or desirable for some insn | |
4512 | operand. | |
4513 | ||
4514 | The syntax and semantics are otherwise identical to | |
4515 | @code{define_constraint}. | |
4516 | @end deffn | |
4517 | ||
f38840db ZW |
4518 | @deffn {MD Expression} define_address_constraint name docstring exp |
4519 | Use this expression for constraints that match a subset of all address | |
4520 | operands: that is, @code{reload} can make the constraint match by | |
4521 | converting the operand to the form @samp{@w{(reg @var{X})}}, again | |
4522 | with @var{X} a base register. | |
4523 | ||
4524 | Constraints defined with @code{define_address_constraint} can only be | |
4525 | used with the @code{address_operand} predicate, or machine-specific | |
4526 | predicates that work the same way. They are treated analogously to | |
4527 | the generic @samp{p} constraint. | |
4528 | ||
4529 | The syntax and semantics are otherwise identical to | |
4530 | @code{define_constraint}. | |
4531 | @end deffn | |
4532 | ||
4533 | For historical reasons, names beginning with the letters @samp{G H} | |
4534 | are reserved for constraints that match only @code{const_double}s, and | |
4535 | names beginning with the letters @samp{I J K L M N O P} are reserved | |
4536 | for constraints that match only @code{const_int}s. This may change in | |
4537 | the future. For the time being, constraints with these names must be | |
4538 | written in a stylized form, so that @code{genpreds} can tell you did | |
4539 | it correctly: | |
4540 | ||
4541 | @smallexample | |
4542 | @group | |
4543 | (define_constraint "[@var{GHIJKLMNOP}]@dots{}" | |
4544 | "@var{doc}@dots{}" | |
4545 | (and (match_code "const_int") ; @r{@code{const_double} for G/H} | |
4546 | @var{condition}@dots{})) ; @r{usually a @code{match_test}} | |
4547 | @end group | |
4548 | @end smallexample | |
4549 | @c the semicolons line up in the formatted manual | |
4550 | ||
4551 | It is fine to use names beginning with other letters for constraints | |
4552 | that match @code{const_double}s or @code{const_int}s. | |
4553 | ||
4554 | Each docstring in a constraint definition should be one or more complete | |
4555 | sentences, marked up in Texinfo format. @emph{They are currently unused.} | |
4556 | In the future they will be copied into the GCC manual, in @ref{Machine | |
4557 | Constraints}, replacing the hand-maintained tables currently found in | |
4558 | that section. Also, in the future the compiler may use this to give | |
4559 | more helpful diagnostics when poor choice of @code{asm} constraints | |
4560 | causes a reload failure. | |
4561 | ||
4562 | If you put the pseudo-Texinfo directive @samp{@@internal} at the | |
4563 | beginning of a docstring, then (in the future) it will appear only in | |
4564 | the internals manual's version of the machine-specific constraint tables. | |
4565 | Use this for constraints that should not appear in @code{asm} statements. | |
4566 | ||
4567 | @node C Constraint Interface | |
4568 | @subsection Testing constraints from C | |
4569 | @cindex testing constraints | |
4570 | @cindex constraints, testing | |
4571 | ||
4572 | It is occasionally useful to test a constraint from C code rather than | |
4573 | implicitly via the constraint string in a @code{match_operand}. The | |
4574 | generated file @file{tm_p.h} declares a few interfaces for working | |
8677664e RS |
4575 | with constraints. At present these are defined for all constraints |
4576 | except @code{g} (which is equivalent to @code{general_operand}). | |
f38840db ZW |
4577 | |
4578 | Some valid constraint names are not valid C identifiers, so there is a | |
4579 | mangling scheme for referring to them from C@. Constraint names that | |
4580 | do not contain angle brackets or underscores are left unchanged. | |
4581 | Underscores are doubled, each @samp{<} is replaced with @samp{_l}, and | |
4582 | each @samp{>} with @samp{_g}. Here are some examples: | |
4583 | ||
4584 | @c the @c's prevent double blank lines in the printed manual. | |
4585 | @example | |
4586 | @multitable {Original} {Mangled} | |
cccb0908 | 4587 | @item @strong{Original} @tab @strong{Mangled} @c |
f38840db ZW |
4588 | @item @code{x} @tab @code{x} @c |
4589 | @item @code{P42x} @tab @code{P42x} @c | |
4590 | @item @code{P4_x} @tab @code{P4__x} @c | |
4591 | @item @code{P4>x} @tab @code{P4_gx} @c | |
4592 | @item @code{P4>>} @tab @code{P4_g_g} @c | |
4593 | @item @code{P4_g>} @tab @code{P4__g_g} @c | |
4594 | @end multitable | |
4595 | @end example | |
4596 | ||
4597 | Throughout this section, the variable @var{c} is either a constraint | |
4598 | in the abstract sense, or a constant from @code{enum constraint_num}; | |
4599 | the variable @var{m} is a mangled constraint name (usually as part of | |
4600 | a larger identifier). | |
4601 | ||
4602 | @deftp Enum constraint_num | |
8677664e | 4603 | For each constraint except @code{g}, there is a corresponding |
f38840db ZW |
4604 | enumeration constant: @samp{CONSTRAINT_} plus the mangled name of the |
4605 | constraint. Functions that take an @code{enum constraint_num} as an | |
4606 | argument expect one of these constants. | |
f38840db ZW |
4607 | @end deftp |
4608 | ||
4609 | @deftypefun {inline bool} satisfies_constraint_@var{m} (rtx @var{exp}) | |
8677664e | 4610 | For each non-register constraint @var{m} except @code{g}, there is |
f38840db ZW |
4611 | one of these functions; it returns @code{true} if @var{exp} satisfies the |
4612 | constraint. These functions are only visible if @file{rtl.h} was included | |
4613 | before @file{tm_p.h}. | |
4614 | @end deftypefun | |
4615 | ||
4616 | @deftypefun bool constraint_satisfied_p (rtx @var{exp}, enum constraint_num @var{c}) | |
4617 | Like the @code{satisfies_constraint_@var{m}} functions, but the | |
4618 | constraint to test is given as an argument, @var{c}. If @var{c} | |
4619 | specifies a register constraint, this function will always return | |
4620 | @code{false}. | |
4621 | @end deftypefun | |
4622 | ||
2aeedf58 | 4623 | @deftypefun {enum reg_class} reg_class_for_constraint (enum constraint_num @var{c}) |
f38840db ZW |
4624 | Returns the register class associated with @var{c}. If @var{c} is not |
4625 | a register constraint, or those registers are not available for the | |
4626 | currently selected subtarget, returns @code{NO_REGS}. | |
4627 | @end deftypefun | |
4628 | ||
4629 | Here is an example use of @code{satisfies_constraint_@var{m}}. In | |
4630 | peephole optimizations (@pxref{Peephole Definitions}), operand | |
4631 | constraint strings are ignored, so if there are relevant constraints, | |
4632 | they must be tested in the C condition. In the example, the | |
4633 | optimization is applied if operand 2 does @emph{not} satisfy the | |
4634 | @samp{K} constraint. (This is a simplified version of a peephole | |
4635 | definition from the i386 machine description.) | |
4636 | ||
4637 | @smallexample | |
4638 | (define_peephole2 | |
4639 | [(match_scratch:SI 3 "r") | |
4640 | (set (match_operand:SI 0 "register_operand" "") | |
6ccde948 RW |
4641 | (mult:SI (match_operand:SI 1 "memory_operand" "") |
4642 | (match_operand:SI 2 "immediate_operand" "")))] | |
f38840db ZW |
4643 | |
4644 | "!satisfies_constraint_K (operands[2])" | |
4645 | ||
4646 | [(set (match_dup 3) (match_dup 1)) | |
4647 | (set (match_dup 0) (mult:SI (match_dup 3) (match_dup 2)))] | |
4648 | ||
4649 | "") | |
4650 | @end smallexample | |
4651 | ||
03dda8e3 RK |
4652 | @node Standard Names |
4653 | @section Standard Pattern Names For Generation | |
4654 | @cindex standard pattern names | |
4655 | @cindex pattern names | |
4656 | @cindex names, pattern | |
4657 | ||
4658 | Here is a table of the instruction names that are meaningful in the RTL | |
4659 | generation pass of the compiler. Giving one of these names to an | |
4660 | instruction pattern tells the RTL generation pass that it can use the | |
556e0f21 | 4661 | pattern to accomplish a certain task. |
03dda8e3 RK |
4662 | |
4663 | @table @asis | |
4664 | @cindex @code{mov@var{m}} instruction pattern | |
4665 | @item @samp{mov@var{m}} | |
4bd0bee9 | 4666 | Here @var{m} stands for a two-letter machine mode name, in lowercase. |
03dda8e3 RK |
4667 | This instruction pattern moves data with that machine mode from operand |
4668 | 1 to operand 0. For example, @samp{movsi} moves full-word data. | |
4669 | ||
4670 | If operand 0 is a @code{subreg} with mode @var{m} of a register whose | |
4671 | own mode is wider than @var{m}, the effect of this instruction is | |
4672 | to store the specified value in the part of the register that corresponds | |
8feb4e28 JL |
4673 | to mode @var{m}. Bits outside of @var{m}, but which are within the |
4674 | same target word as the @code{subreg} are undefined. Bits which are | |
4675 | outside the target word are left unchanged. | |
03dda8e3 RK |
4676 | |
4677 | This class of patterns is special in several ways. First of all, each | |
65945ec1 HPN |
4678 | of these names up to and including full word size @emph{must} be defined, |
4679 | because there is no other way to copy a datum from one place to another. | |
4680 | If there are patterns accepting operands in larger modes, | |
4681 | @samp{mov@var{m}} must be defined for integer modes of those sizes. | |
03dda8e3 RK |
4682 | |
4683 | Second, these patterns are not used solely in the RTL generation pass. | |
4684 | Even the reload pass can generate move insns to copy values from stack | |
4685 | slots into temporary registers. When it does so, one of the operands is | |
4686 | a hard register and the other is an operand that can need to be reloaded | |
4687 | into a register. | |
4688 | ||
4689 | @findex force_reg | |
4690 | Therefore, when given such a pair of operands, the pattern must generate | |
4691 | RTL which needs no reloading and needs no temporary registers---no | |
4692 | registers other than the operands. For example, if you support the | |
4693 | pattern with a @code{define_expand}, then in such a case the | |
4694 | @code{define_expand} mustn't call @code{force_reg} or any other such | |
4695 | function which might generate new pseudo registers. | |
4696 | ||
4697 | This requirement exists even for subword modes on a RISC machine where | |
4698 | fetching those modes from memory normally requires several insns and | |
39ed8974 | 4699 | some temporary registers. |
03dda8e3 RK |
4700 | |
4701 | @findex change_address | |
4702 | During reload a memory reference with an invalid address may be passed | |
4703 | as an operand. Such an address will be replaced with a valid address | |
4704 | later in the reload pass. In this case, nothing may be done with the | |
4705 | address except to use it as it stands. If it is copied, it will not be | |
4706 | replaced with a valid address. No attempt should be made to make such | |
4707 | an address into a valid address and no routine (such as | |
4708 | @code{change_address}) that will do so may be called. Note that | |
4709 | @code{general_operand} will fail when applied to such an address. | |
4710 | ||
4711 | @findex reload_in_progress | |
4712 | The global variable @code{reload_in_progress} (which must be explicitly | |
4713 | declared if required) can be used to determine whether such special | |
4714 | handling is required. | |
4715 | ||
4716 | The variety of operands that have reloads depends on the rest of the | |
4717 | machine description, but typically on a RISC machine these can only be | |
4718 | pseudo registers that did not get hard registers, while on other | |
4719 | machines explicit memory references will get optional reloads. | |
4720 | ||
4721 | If a scratch register is required to move an object to or from memory, | |
f1db3576 JL |
4722 | it can be allocated using @code{gen_reg_rtx} prior to life analysis. |
4723 | ||
9c34dbbf | 4724 | If there are cases which need scratch registers during or after reload, |
8a99f6f9 | 4725 | you must provide an appropriate secondary_reload target hook. |
03dda8e3 | 4726 | |
ef4375b2 KZ |
4727 | @findex can_create_pseudo_p |
4728 | The macro @code{can_create_pseudo_p} can be used to determine if it | |
f1db3576 JL |
4729 | is unsafe to create new pseudo registers. If this variable is nonzero, then |
4730 | it is unsafe to call @code{gen_reg_rtx} to allocate a new pseudo. | |
4731 | ||
956d6950 | 4732 | The constraints on a @samp{mov@var{m}} must permit moving any hard |
03dda8e3 | 4733 | register to any other hard register provided that |
f939c3e6 | 4734 | @code{TARGET_HARD_REGNO_MODE_OK} permits mode @var{m} in both registers and |
de8f4b07 AS |
4735 | @code{TARGET_REGISTER_MOVE_COST} applied to their classes returns a value |
4736 | of 2. | |
03dda8e3 | 4737 | |
956d6950 | 4738 | It is obligatory to support floating point @samp{mov@var{m}} |
03dda8e3 RK |
4739 | instructions into and out of any registers that can hold fixed point |
4740 | values, because unions and structures (which have modes @code{SImode} or | |
4741 | @code{DImode}) can be in those registers and they may have floating | |
4742 | point members. | |
4743 | ||
956d6950 | 4744 | There may also be a need to support fixed point @samp{mov@var{m}} |
03dda8e3 RK |
4745 | instructions in and out of floating point registers. Unfortunately, I |
4746 | have forgotten why this was so, and I don't know whether it is still | |
f939c3e6 | 4747 | true. If @code{TARGET_HARD_REGNO_MODE_OK} rejects fixed point values in |
03dda8e3 | 4748 | floating point registers, then the constraints of the fixed point |
956d6950 | 4749 | @samp{mov@var{m}} instructions must be designed to avoid ever trying to |
03dda8e3 RK |
4750 | reload into a floating point register. |
4751 | ||
4752 | @cindex @code{reload_in} instruction pattern | |
4753 | @cindex @code{reload_out} instruction pattern | |
4754 | @item @samp{reload_in@var{m}} | |
4755 | @itemx @samp{reload_out@var{m}} | |
8a99f6f9 R |
4756 | These named patterns have been obsoleted by the target hook |
4757 | @code{secondary_reload}. | |
4758 | ||
03dda8e3 RK |
4759 | Like @samp{mov@var{m}}, but used when a scratch register is required to |
4760 | move between operand 0 and operand 1. Operand 2 describes the scratch | |
4761 | register. See the discussion of the @code{SECONDARY_RELOAD_CLASS} | |
4762 | macro in @pxref{Register Classes}. | |
4763 | ||
d989f648 | 4764 | There are special restrictions on the form of the @code{match_operand}s |
f282ffb3 | 4765 | used in these patterns. First, only the predicate for the reload |
560dbedd RH |
4766 | operand is examined, i.e., @code{reload_in} examines operand 1, but not |
4767 | the predicates for operand 0 or 2. Second, there may be only one | |
d989f648 RH |
4768 | alternative in the constraints. Third, only a single register class |
4769 | letter may be used for the constraint; subsequent constraint letters | |
4770 | are ignored. As a special exception, an empty constraint string | |
4771 | matches the @code{ALL_REGS} register class. This may relieve ports | |
4772 | of the burden of defining an @code{ALL_REGS} constraint letter just | |
4773 | for these patterns. | |
4774 | ||
03dda8e3 RK |
4775 | @cindex @code{movstrict@var{m}} instruction pattern |
4776 | @item @samp{movstrict@var{m}} | |
4777 | Like @samp{mov@var{m}} except that if operand 0 is a @code{subreg} | |
4778 | with mode @var{m} of a register whose natural mode is wider, | |
4779 | the @samp{movstrict@var{m}} instruction is guaranteed not to alter | |
4780 | any of the register except the part which belongs to mode @var{m}. | |
4781 | ||
1e0598e2 RH |
4782 | @cindex @code{movmisalign@var{m}} instruction pattern |
4783 | @item @samp{movmisalign@var{m}} | |
4784 | This variant of a move pattern is designed to load or store a value | |
4785 | from a memory address that is not naturally aligned for its mode. | |
4786 | For a store, the memory will be in operand 0; for a load, the memory | |
4787 | will be in operand 1. The other operand is guaranteed not to be a | |
4788 | memory, so that it's easy to tell whether this is a load or store. | |
4789 | ||
4790 | This pattern is used by the autovectorizer, and when expanding a | |
4791 | @code{MISALIGNED_INDIRECT_REF} expression. | |
4792 | ||
03dda8e3 RK |
4793 | @cindex @code{load_multiple} instruction pattern |
4794 | @item @samp{load_multiple} | |
4795 | Load several consecutive memory locations into consecutive registers. | |
4796 | Operand 0 is the first of the consecutive registers, operand 1 | |
4797 | is the first memory location, and operand 2 is a constant: the | |
4798 | number of consecutive registers. | |
4799 | ||
4800 | Define this only if the target machine really has such an instruction; | |
4801 | do not define this if the most efficient way of loading consecutive | |
4802 | registers from memory is to do them one at a time. | |
4803 | ||
4804 | On some machines, there are restrictions as to which consecutive | |
4805 | registers can be stored into memory, such as particular starting or | |
4806 | ending register numbers or only a range of valid counts. For those | |
4807 | machines, use a @code{define_expand} (@pxref{Expander Definitions}) | |
4808 | and make the pattern fail if the restrictions are not met. | |
4809 | ||
4810 | Write the generated insn as a @code{parallel} with elements being a | |
4811 | @code{set} of one register from the appropriate memory location (you may | |
4812 | also need @code{use} or @code{clobber} elements). Use a | |
4813 | @code{match_parallel} (@pxref{RTL Template}) to recognize the insn. See | |
c9693e96 | 4814 | @file{rs6000.md} for examples of the use of this insn pattern. |
03dda8e3 RK |
4815 | |
4816 | @cindex @samp{store_multiple} instruction pattern | |
4817 | @item @samp{store_multiple} | |
4818 | Similar to @samp{load_multiple}, but store several consecutive registers | |
4819 | into consecutive memory locations. Operand 0 is the first of the | |
4820 | consecutive memory locations, operand 1 is the first register, and | |
4821 | operand 2 is a constant: the number of consecutive registers. | |
4822 | ||
272c6793 RS |
4823 | @cindex @code{vec_load_lanes@var{m}@var{n}} instruction pattern |
4824 | @item @samp{vec_load_lanes@var{m}@var{n}} | |
4825 | Perform an interleaved load of several vectors from memory operand 1 | |
4826 | into register operand 0. Both operands have mode @var{m}. The register | |
4827 | operand is viewed as holding consecutive vectors of mode @var{n}, | |
4828 | while the memory operand is a flat array that contains the same number | |
4829 | of elements. The operation is equivalent to: | |
4830 | ||
4831 | @smallexample | |
4832 | int c = GET_MODE_SIZE (@var{m}) / GET_MODE_SIZE (@var{n}); | |
4833 | for (j = 0; j < GET_MODE_NUNITS (@var{n}); j++) | |
4834 | for (i = 0; i < c; i++) | |
4835 | operand0[i][j] = operand1[j * c + i]; | |
4836 | @end smallexample | |
4837 | ||
4838 | For example, @samp{vec_load_lanestiv4hi} loads 8 16-bit values | |
4839 | from memory into a register of mode @samp{TI}@. The register | |
4840 | contains two consecutive vectors of mode @samp{V4HI}@. | |
4841 | ||
4842 | This pattern can only be used if: | |
4843 | @smallexample | |
4844 | TARGET_ARRAY_MODE_SUPPORTED_P (@var{n}, @var{c}) | |
4845 | @end smallexample | |
4846 | is true. GCC assumes that, if a target supports this kind of | |
4847 | instruction for some mode @var{n}, it also supports unaligned | |
4848 | loads for vectors of mode @var{n}. | |
4849 | ||
a54a5997 RS |
4850 | This pattern is not allowed to @code{FAIL}. |
4851 | ||
272c6793 RS |
4852 | @cindex @code{vec_store_lanes@var{m}@var{n}} instruction pattern |
4853 | @item @samp{vec_store_lanes@var{m}@var{n}} | |
4854 | Equivalent to @samp{vec_load_lanes@var{m}@var{n}}, with the memory | |
4855 | and register operands reversed. That is, the instruction is | |
4856 | equivalent to: | |
4857 | ||
4858 | @smallexample | |
4859 | int c = GET_MODE_SIZE (@var{m}) / GET_MODE_SIZE (@var{n}); | |
4860 | for (j = 0; j < GET_MODE_NUNITS (@var{n}); j++) | |
4861 | for (i = 0; i < c; i++) | |
4862 | operand0[j * c + i] = operand1[i][j]; | |
4863 | @end smallexample | |
4864 | ||
4865 | for a memory operand 0 and register operand 1. | |
4866 | ||
a54a5997 RS |
4867 | This pattern is not allowed to @code{FAIL}. |
4868 | ||
ef1140a9 JH |
4869 | @cindex @code{vec_set@var{m}} instruction pattern |
4870 | @item @samp{vec_set@var{m}} | |
4871 | Set given field in the vector value. Operand 0 is the vector to modify, | |
4872 | operand 1 is new value of field and operand 2 specify the field index. | |
4873 | ||
ff03930a JJ |
4874 | @cindex @code{vec_extract@var{m}@var{n}} instruction pattern |
4875 | @item @samp{vec_extract@var{m}@var{n}} | |
ef1140a9 | 4876 | Extract given field from the vector value. Operand 1 is the vector, operand 2 |
ff03930a JJ |
4877 | specify field index and operand 0 place to store value into. The |
4878 | @var{n} mode is the mode of the field or vector of fields that should be | |
4879 | extracted, should be either element mode of the vector mode @var{m}, or | |
4880 | a vector mode with the same element mode and smaller number of elements. | |
4881 | If @var{n} is a vector mode, the index is counted in units of that mode. | |
4882 | ||
4883 | @cindex @code{vec_init@var{m}@var{n}} instruction pattern | |
4884 | @item @samp{vec_init@var{m}@var{n}} | |
425a2bde | 4885 | Initialize the vector to given values. Operand 0 is the vector to initialize |
ff03930a JJ |
4886 | and operand 1 is parallel containing values for individual fields. The |
4887 | @var{n} mode is the mode of the elements, should be either element mode of | |
4888 | the vector mode @var{m}, or a vector mode with the same element mode and | |
4889 | smaller number of elements. | |
ef1140a9 | 4890 | |
12fb875f IE |
4891 | @cindex @code{vec_cmp@var{m}@var{n}} instruction pattern |
4892 | @item @samp{vec_cmp@var{m}@var{n}} | |
4893 | Output a vector comparison. Operand 0 of mode @var{n} is the destination for | |
4894 | predicate in operand 1 which is a signed vector comparison with operands of | |
4895 | mode @var{m} in operands 2 and 3. Predicate is computed by element-wise | |
4896 | evaluation of the vector comparison with a truth value of all-ones and a false | |
4897 | value of all-zeros. | |
4898 | ||
4899 | @cindex @code{vec_cmpu@var{m}@var{n}} instruction pattern | |
4900 | @item @samp{vec_cmpu@var{m}@var{n}} | |
4901 | Similar to @code{vec_cmp@var{m}@var{n}} but perform unsigned vector comparison. | |
4902 | ||
96592eed JJ |
4903 | @cindex @code{vec_cmpeq@var{m}@var{n}} instruction pattern |
4904 | @item @samp{vec_cmpeq@var{m}@var{n}} | |
4905 | Similar to @code{vec_cmp@var{m}@var{n}} but perform equality or non-equality | |
4906 | vector comparison only. If @code{vec_cmp@var{m}@var{n}} | |
4907 | or @code{vec_cmpu@var{m}@var{n}} instruction pattern is supported, | |
4908 | it will be preferred over @code{vec_cmpeq@var{m}@var{n}}, so there is | |
4909 | no need to define this instruction pattern if the others are supported. | |
4910 | ||
e9e1d143 RG |
4911 | @cindex @code{vcond@var{m}@var{n}} instruction pattern |
4912 | @item @samp{vcond@var{m}@var{n}} | |
4913 | Output a conditional vector move. Operand 0 is the destination to | |
4914 | receive a combination of operand 1 and operand 2, which are of mode @var{m}, | |
12fb875f | 4915 | dependent on the outcome of the predicate in operand 3 which is a signed |
e9e1d143 RG |
4916 | vector comparison with operands of mode @var{n} in operands 4 and 5. The |
4917 | modes @var{m} and @var{n} should have the same size. Operand 0 | |
4918 | will be set to the value @var{op1} & @var{msk} | @var{op2} & ~@var{msk} | |
4919 | where @var{msk} is computed by element-wise evaluation of the vector | |
4920 | comparison with a truth value of all-ones and a false value of all-zeros. | |
4921 | ||
12fb875f IE |
4922 | @cindex @code{vcondu@var{m}@var{n}} instruction pattern |
4923 | @item @samp{vcondu@var{m}@var{n}} | |
4924 | Similar to @code{vcond@var{m}@var{n}} but performs unsigned vector | |
4925 | comparison. | |
4926 | ||
96592eed JJ |
4927 | @cindex @code{vcondeq@var{m}@var{n}} instruction pattern |
4928 | @item @samp{vcondeq@var{m}@var{n}} | |
4929 | Similar to @code{vcond@var{m}@var{n}} but performs equality or | |
4930 | non-equality vector comparison only. If @code{vcond@var{m}@var{n}} | |
4931 | or @code{vcondu@var{m}@var{n}} instruction pattern is supported, | |
4932 | it will be preferred over @code{vcondeq@var{m}@var{n}}, so there is | |
4933 | no need to define this instruction pattern if the others are supported. | |
4934 | ||
12fb875f IE |
4935 | @cindex @code{vcond_mask_@var{m}@var{n}} instruction pattern |
4936 | @item @samp{vcond_mask_@var{m}@var{n}} | |
4937 | Similar to @code{vcond@var{m}@var{n}} but operand 3 holds a pre-computed | |
4938 | result of vector comparison. | |
4939 | ||
4940 | @cindex @code{maskload@var{m}@var{n}} instruction pattern | |
4941 | @item @samp{maskload@var{m}@var{n}} | |
4942 | Perform a masked load of vector from memory operand 1 of mode @var{m} | |
4943 | into register operand 0. Mask is provided in register operand 2 of | |
4944 | mode @var{n}. | |
4945 | ||
a54a5997 RS |
4946 | This pattern is not allowed to @code{FAIL}. |
4947 | ||
12fb875f | 4948 | @cindex @code{maskstore@var{m}@var{n}} instruction pattern |
a54a5997 | 4949 | @item @samp{maskstore@var{m}@var{n}} |
12fb875f IE |
4950 | Perform a masked store of vector from register operand 1 of mode @var{m} |
4951 | into memory operand 0. Mask is provided in register operand 2 of | |
4952 | mode @var{n}. | |
4953 | ||
a54a5997 RS |
4954 | This pattern is not allowed to @code{FAIL}. |
4955 | ||
2205ed25 RH |
4956 | @cindex @code{vec_perm@var{m}} instruction pattern |
4957 | @item @samp{vec_perm@var{m}} | |
4958 | Output a (variable) vector permutation. Operand 0 is the destination | |
4959 | to receive elements from operand 1 and operand 2, which are of mode | |
4960 | @var{m}. Operand 3 is the @dfn{selector}. It is an integral mode | |
4961 | vector of the same width and number of elements as mode @var{m}. | |
4962 | ||
4963 | The input elements are numbered from 0 in operand 1 through | |
4964 | @math{2*@var{N}-1} in operand 2. The elements of the selector must | |
4965 | be computed modulo @math{2*@var{N}}. Note that if | |
4966 | @code{rtx_equal_p(operand1, operand2)}, this can be implemented | |
4967 | with just operand 1 and selector elements modulo @var{N}. | |
4968 | ||
d7943c8b RH |
4969 | In order to make things easy for a number of targets, if there is no |
4970 | @samp{vec_perm} pattern for mode @var{m}, but there is for mode @var{q} | |
4971 | where @var{q} is a vector of @code{QImode} of the same width as @var{m}, | |
4972 | the middle-end will lower the mode @var{m} @code{VEC_PERM_EXPR} to | |
4973 | mode @var{q}. | |
4974 | ||
82675d94 | 4975 | @cindex @code{vec_perm_const@var{m}} instruction pattern |
2205ed25 RH |
4976 | @item @samp{vec_perm_const@var{m}} |
4977 | Like @samp{vec_perm} except that the permutation is a compile-time | |
4978 | constant. That is, operand 3, the @dfn{selector}, is a @code{CONST_VECTOR}. | |
4979 | ||
4980 | Some targets cannot perform a permutation with a variable selector, | |
4981 | but can efficiently perform a constant permutation. Further, the | |
4982 | target hook @code{vec_perm_ok} is queried to determine if the | |
4983 | specific constant permutation is available efficiently; the named | |
4984 | pattern is never expanded without @code{vec_perm_ok} returning true. | |
4985 | ||
4986 | There is no need for a target to supply both @samp{vec_perm@var{m}} | |
4987 | and @samp{vec_perm_const@var{m}} if the former can trivially implement | |
4988 | the operation with, say, the vector constant loaded into a register. | |
4989 | ||
759915ca EC |
4990 | @cindex @code{push@var{m}1} instruction pattern |
4991 | @item @samp{push@var{m}1} | |
299c5111 | 4992 | Output a push instruction. Operand 0 is value to push. Used only when |
38f4324c JH |
4993 | @code{PUSH_ROUNDING} is defined. For historical reason, this pattern may be |
4994 | missing and in such case an @code{mov} expander is used instead, with a | |
6e9aac46 | 4995 | @code{MEM} expression forming the push operation. The @code{mov} expander |
38f4324c JH |
4996 | method is deprecated. |
4997 | ||
03dda8e3 RK |
4998 | @cindex @code{add@var{m}3} instruction pattern |
4999 | @item @samp{add@var{m}3} | |
5000 | Add operand 2 and operand 1, storing the result in operand 0. All operands | |
5001 | must have mode @var{m}. This can be used even on two-address machines, by | |
5002 | means of constraints requiring operands 1 and 0 to be the same location. | |
5003 | ||
0f996086 CF |
5004 | @cindex @code{ssadd@var{m}3} instruction pattern |
5005 | @cindex @code{usadd@var{m}3} instruction pattern | |
03dda8e3 | 5006 | @cindex @code{sub@var{m}3} instruction pattern |
0f996086 CF |
5007 | @cindex @code{sssub@var{m}3} instruction pattern |
5008 | @cindex @code{ussub@var{m}3} instruction pattern | |
03dda8e3 | 5009 | @cindex @code{mul@var{m}3} instruction pattern |
0f996086 CF |
5010 | @cindex @code{ssmul@var{m}3} instruction pattern |
5011 | @cindex @code{usmul@var{m}3} instruction pattern | |
03dda8e3 | 5012 | @cindex @code{div@var{m}3} instruction pattern |
0f996086 | 5013 | @cindex @code{ssdiv@var{m}3} instruction pattern |
03dda8e3 | 5014 | @cindex @code{udiv@var{m}3} instruction pattern |
0f996086 | 5015 | @cindex @code{usdiv@var{m}3} instruction pattern |
03dda8e3 RK |
5016 | @cindex @code{mod@var{m}3} instruction pattern |
5017 | @cindex @code{umod@var{m}3} instruction pattern | |
03dda8e3 RK |
5018 | @cindex @code{umin@var{m}3} instruction pattern |
5019 | @cindex @code{umax@var{m}3} instruction pattern | |
5020 | @cindex @code{and@var{m}3} instruction pattern | |
5021 | @cindex @code{ior@var{m}3} instruction pattern | |
5022 | @cindex @code{xor@var{m}3} instruction pattern | |
0f996086 | 5023 | @item @samp{ssadd@var{m}3}, @samp{usadd@var{m}3} |
f457c50c AS |
5024 | @itemx @samp{sub@var{m}3}, @samp{sssub@var{m}3}, @samp{ussub@var{m}3} |
5025 | @itemx @samp{mul@var{m}3}, @samp{ssmul@var{m}3}, @samp{usmul@var{m}3} | |
0f996086 CF |
5026 | @itemx @samp{div@var{m}3}, @samp{ssdiv@var{m}3} |
5027 | @itemx @samp{udiv@var{m}3}, @samp{usdiv@var{m}3} | |
7ae4d8d4 RH |
5028 | @itemx @samp{mod@var{m}3}, @samp{umod@var{m}3} |
5029 | @itemx @samp{umin@var{m}3}, @samp{umax@var{m}3} | |
03dda8e3 RK |
5030 | @itemx @samp{and@var{m}3}, @samp{ior@var{m}3}, @samp{xor@var{m}3} |
5031 | Similar, for other arithmetic operations. | |
7ae4d8d4 | 5032 | |
481efdd9 EB |
5033 | @cindex @code{addv@var{m}4} instruction pattern |
5034 | @item @samp{addv@var{m}4} | |
5035 | Like @code{add@var{m}3} but takes a @code{code_label} as operand 3 and | |
5036 | emits code to jump to it if signed overflow occurs during the addition. | |
5037 | This pattern is used to implement the built-in functions performing | |
5038 | signed integer addition with overflow checking. | |
5039 | ||
5040 | @cindex @code{subv@var{m}4} instruction pattern | |
5041 | @cindex @code{mulv@var{m}4} instruction pattern | |
5042 | @item @samp{subv@var{m}4}, @samp{mulv@var{m}4} | |
5043 | Similar, for other signed arithmetic operations. | |
5044 | ||
cde9d596 RH |
5045 | @cindex @code{uaddv@var{m}4} instruction pattern |
5046 | @item @samp{uaddv@var{m}4} | |
5047 | Like @code{addv@var{m}4} but for unsigned addition. That is to | |
5048 | say, the operation is the same as signed addition but the jump | |
481efdd9 EB |
5049 | is taken only on unsigned overflow. |
5050 | ||
cde9d596 RH |
5051 | @cindex @code{usubv@var{m}4} instruction pattern |
5052 | @cindex @code{umulv@var{m}4} instruction pattern | |
5053 | @item @samp{usubv@var{m}4}, @samp{umulv@var{m}4} | |
5054 | Similar, for other unsigned arithmetic operations. | |
5055 | ||
481efdd9 EB |
5056 | @cindex @code{addptr@var{m}3} instruction pattern |
5057 | @item @samp{addptr@var{m}3} | |
5058 | Like @code{add@var{m}3} but is guaranteed to only be used for address | |
5059 | calculations. The expanded code is not allowed to clobber the | |
5060 | condition code. It only needs to be defined if @code{add@var{m}3} | |
5061 | sets the condition code. If adds used for address calculations and | |
5062 | normal adds are not compatible it is required to expand a distinct | |
5063 | pattern (e.g. using an unspec). The pattern is used by LRA to emit | |
5064 | address calculations. @code{add@var{m}3} is used if | |
5065 | @code{addptr@var{m}3} is not defined. | |
5066 | ||
1b1562a5 MM |
5067 | @cindex @code{fma@var{m}4} instruction pattern |
5068 | @item @samp{fma@var{m}4} | |
5069 | Multiply operand 2 and operand 1, then add operand 3, storing the | |
d6373302 KZ |
5070 | result in operand 0 without doing an intermediate rounding step. All |
5071 | operands must have mode @var{m}. This pattern is used to implement | |
5072 | the @code{fma}, @code{fmaf}, and @code{fmal} builtin functions from | |
5073 | the ISO C99 standard. | |
1b1562a5 | 5074 | |
16949072 RG |
5075 | @cindex @code{fms@var{m}4} instruction pattern |
5076 | @item @samp{fms@var{m}4} | |
5077 | Like @code{fma@var{m}4}, except operand 3 subtracted from the | |
5078 | product instead of added to the product. This is represented | |
5079 | in the rtl as | |
5080 | ||
5081 | @smallexample | |
5082 | (fma:@var{m} @var{op1} @var{op2} (neg:@var{m} @var{op3})) | |
5083 | @end smallexample | |
5084 | ||
5085 | @cindex @code{fnma@var{m}4} instruction pattern | |
5086 | @item @samp{fnma@var{m}4} | |
5087 | Like @code{fma@var{m}4} except that the intermediate product | |
5088 | is negated before being added to operand 3. This is represented | |
5089 | in the rtl as | |
5090 | ||
5091 | @smallexample | |
5092 | (fma:@var{m} (neg:@var{m} @var{op1}) @var{op2} @var{op3}) | |
5093 | @end smallexample | |
5094 | ||
5095 | @cindex @code{fnms@var{m}4} instruction pattern | |
5096 | @item @samp{fnms@var{m}4} | |
5097 | Like @code{fms@var{m}4} except that the intermediate product | |
5098 | is negated before subtracting operand 3. This is represented | |
5099 | in the rtl as | |
5100 | ||
5101 | @smallexample | |
5102 | (fma:@var{m} (neg:@var{m} @var{op1}) @var{op2} (neg:@var{m} @var{op3})) | |
5103 | @end smallexample | |
5104 | ||
b71b019a JH |
5105 | @cindex @code{min@var{m}3} instruction pattern |
5106 | @cindex @code{max@var{m}3} instruction pattern | |
7ae4d8d4 RH |
5107 | @item @samp{smin@var{m}3}, @samp{smax@var{m}3} |
5108 | Signed minimum and maximum operations. When used with floating point, | |
5109 | if both operands are zeros, or if either operand is @code{NaN}, then | |
5110 | it is unspecified which of the two operands is returned as the result. | |
03dda8e3 | 5111 | |
ccb57bb0 DS |
5112 | @cindex @code{fmin@var{m}3} instruction pattern |
5113 | @cindex @code{fmax@var{m}3} instruction pattern | |
5114 | @item @samp{fmin@var{m}3}, @samp{fmax@var{m}3} | |
5115 | IEEE-conformant minimum and maximum operations. If one operand is a quiet | |
5116 | @code{NaN}, then the other operand is returned. If both operands are quiet | |
5117 | @code{NaN}, then a quiet @code{NaN} is returned. In the case when gcc supports | |
18ea359a | 5118 | signaling @code{NaN} (-fsignaling-nans) an invalid floating point exception is |
ccb57bb0 DS |
5119 | raised and a quiet @code{NaN} is returned. |
5120 | ||
a54a5997 RS |
5121 | All operands have mode @var{m}, which is a scalar or vector |
5122 | floating-point mode. These patterns are not allowed to @code{FAIL}. | |
5123 | ||
d43a252e AL |
5124 | @cindex @code{reduc_smin_scal_@var{m}} instruction pattern |
5125 | @cindex @code{reduc_smax_scal_@var{m}} instruction pattern | |
5126 | @item @samp{reduc_smin_scal_@var{m}}, @samp{reduc_smax_scal_@var{m}} | |
5127 | Find the signed minimum/maximum of the elements of a vector. The vector is | |
5128 | operand 1, and operand 0 is the scalar result, with mode equal to the mode of | |
5129 | the elements of the input vector. | |
5130 | ||
5131 | @cindex @code{reduc_umin_scal_@var{m}} instruction pattern | |
5132 | @cindex @code{reduc_umax_scal_@var{m}} instruction pattern | |
5133 | @item @samp{reduc_umin_scal_@var{m}}, @samp{reduc_umax_scal_@var{m}} | |
5134 | Find the unsigned minimum/maximum of the elements of a vector. The vector is | |
5135 | operand 1, and operand 0 is the scalar result, with mode equal to the mode of | |
5136 | the elements of the input vector. | |
5137 | ||
5138 | @cindex @code{reduc_plus_scal_@var{m}} instruction pattern | |
5139 | @item @samp{reduc_plus_scal_@var{m}} | |
5140 | Compute the sum of the elements of a vector. The vector is operand 1, and | |
5141 | operand 0 is the scalar result, with mode equal to the mode of the elements of | |
5142 | the input vector. | |
61abee65 | 5143 | |
20f06221 DN |
5144 | @cindex @code{sdot_prod@var{m}} instruction pattern |
5145 | @item @samp{sdot_prod@var{m}} | |
5146 | @cindex @code{udot_prod@var{m}} instruction pattern | |
544aee0d | 5147 | @itemx @samp{udot_prod@var{m}} |
ff2ce160 MS |
5148 | Compute the sum of the products of two signed/unsigned elements. |
5149 | Operand 1 and operand 2 are of the same mode. Their product, which is of a | |
5150 | wider mode, is computed and added to operand 3. Operand 3 is of a mode equal or | |
20f06221 | 5151 | wider than the mode of the product. The result is placed in operand 0, which |
ff2ce160 | 5152 | is of the same mode as operand 3. |
20f06221 | 5153 | |
79d652a5 CH |
5154 | @cindex @code{ssad@var{m}} instruction pattern |
5155 | @item @samp{ssad@var{m}} | |
5156 | @cindex @code{usad@var{m}} instruction pattern | |
5157 | @item @samp{usad@var{m}} | |
5158 | Compute the sum of absolute differences of two signed/unsigned elements. | |
5159 | Operand 1 and operand 2 are of the same mode. Their absolute difference, which | |
5160 | is of a wider mode, is computed and added to operand 3. Operand 3 is of a mode | |
5161 | equal or wider than the mode of the absolute difference. The result is placed | |
5162 | in operand 0, which is of the same mode as operand 3. | |
5163 | ||
97532d1a MC |
5164 | @cindex @code{widen_ssum@var{m3}} instruction pattern |
5165 | @item @samp{widen_ssum@var{m3}} | |
5166 | @cindex @code{widen_usum@var{m3}} instruction pattern | |
5167 | @itemx @samp{widen_usum@var{m3}} | |
ff2ce160 | 5168 | Operands 0 and 2 are of the same mode, which is wider than the mode of |
20f06221 DN |
5169 | operand 1. Add operand 1 to operand 2 and place the widened result in |
5170 | operand 0. (This is used express accumulation of elements into an accumulator | |
5171 | of a wider mode.) | |
5172 | ||
61abee65 | 5173 | @cindex @code{vec_shr_@var{m}} instruction pattern |
e29dfbf0 | 5174 | @item @samp{vec_shr_@var{m}} |
729ff76e | 5175 | Whole vector right shift in bits, i.e. towards element 0. |
61abee65 | 5176 | Operand 1 is a vector to be shifted. |
759915ca | 5177 | Operand 2 is an integer shift amount in bits. |
61abee65 DN |
5178 | Operand 0 is where the resulting shifted vector is stored. |
5179 | The output and input vectors should have the same modes. | |
5180 | ||
8115817b UB |
5181 | @cindex @code{vec_pack_trunc_@var{m}} instruction pattern |
5182 | @item @samp{vec_pack_trunc_@var{m}} | |
5183 | Narrow (demote) and merge the elements of two vectors. Operands 1 and 2 | |
5184 | are vectors of the same mode having N integral or floating point elements | |
0ee2ea09 | 5185 | of size S@. Operand 0 is the resulting vector in which 2*N elements of |
8115817b UB |
5186 | size N/2 are concatenated after narrowing them down using truncation. |
5187 | ||
89d67cca DN |
5188 | @cindex @code{vec_pack_ssat_@var{m}} instruction pattern |
5189 | @cindex @code{vec_pack_usat_@var{m}} instruction pattern | |
8115817b UB |
5190 | @item @samp{vec_pack_ssat_@var{m}}, @samp{vec_pack_usat_@var{m}} |
5191 | Narrow (demote) and merge the elements of two vectors. Operands 1 and 2 | |
5192 | are vectors of the same mode having N integral elements of size S. | |
89d67cca | 5193 | Operand 0 is the resulting vector in which the elements of the two input |
8115817b UB |
5194 | vectors are concatenated after narrowing them down using signed/unsigned |
5195 | saturating arithmetic. | |
89d67cca | 5196 | |
d9987fb4 UB |
5197 | @cindex @code{vec_pack_sfix_trunc_@var{m}} instruction pattern |
5198 | @cindex @code{vec_pack_ufix_trunc_@var{m}} instruction pattern | |
5199 | @item @samp{vec_pack_sfix_trunc_@var{m}}, @samp{vec_pack_ufix_trunc_@var{m}} | |
5200 | Narrow, convert to signed/unsigned integral type and merge the elements | |
5201 | of two vectors. Operands 1 and 2 are vectors of the same mode having N | |
0ee2ea09 | 5202 | floating point elements of size S@. Operand 0 is the resulting vector |
d9987fb4 UB |
5203 | in which 2*N elements of size N/2 are concatenated. |
5204 | ||
89d67cca DN |
5205 | @cindex @code{vec_unpacks_hi_@var{m}} instruction pattern |
5206 | @cindex @code{vec_unpacks_lo_@var{m}} instruction pattern | |
8115817b UB |
5207 | @item @samp{vec_unpacks_hi_@var{m}}, @samp{vec_unpacks_lo_@var{m}} |
5208 | Extract and widen (promote) the high/low part of a vector of signed | |
5209 | integral or floating point elements. The input vector (operand 1) has N | |
0ee2ea09 | 5210 | elements of size S@. Widen (promote) the high/low elements of the vector |
8115817b UB |
5211 | using signed or floating point extension and place the resulting N/2 |
5212 | values of size 2*S in the output vector (operand 0). | |
5213 | ||
89d67cca DN |
5214 | @cindex @code{vec_unpacku_hi_@var{m}} instruction pattern |
5215 | @cindex @code{vec_unpacku_lo_@var{m}} instruction pattern | |
8115817b UB |
5216 | @item @samp{vec_unpacku_hi_@var{m}}, @samp{vec_unpacku_lo_@var{m}} |
5217 | Extract and widen (promote) the high/low part of a vector of unsigned | |
5218 | integral elements. The input vector (operand 1) has N elements of size S. | |
5219 | Widen (promote) the high/low elements of the vector using zero extension and | |
5220 | place the resulting N/2 values of size 2*S in the output vector (operand 0). | |
89d67cca | 5221 | |
d9987fb4 UB |
5222 | @cindex @code{vec_unpacks_float_hi_@var{m}} instruction pattern |
5223 | @cindex @code{vec_unpacks_float_lo_@var{m}} instruction pattern | |
5224 | @cindex @code{vec_unpacku_float_hi_@var{m}} instruction pattern | |
5225 | @cindex @code{vec_unpacku_float_lo_@var{m}} instruction pattern | |
5226 | @item @samp{vec_unpacks_float_hi_@var{m}}, @samp{vec_unpacks_float_lo_@var{m}} | |
5227 | @itemx @samp{vec_unpacku_float_hi_@var{m}}, @samp{vec_unpacku_float_lo_@var{m}} | |
5228 | Extract, convert to floating point type and widen the high/low part of a | |
5229 | vector of signed/unsigned integral elements. The input vector (operand 1) | |
0ee2ea09 | 5230 | has N elements of size S@. Convert the high/low elements of the vector using |
d9987fb4 UB |
5231 | floating point conversion and place the resulting N/2 values of size 2*S in |
5232 | the output vector (operand 0). | |
5233 | ||
89d67cca | 5234 | @cindex @code{vec_widen_umult_hi_@var{m}} instruction pattern |
3f30a9a6 | 5235 | @cindex @code{vec_widen_umult_lo_@var{m}} instruction pattern |
89d67cca DN |
5236 | @cindex @code{vec_widen_smult_hi_@var{m}} instruction pattern |
5237 | @cindex @code{vec_widen_smult_lo_@var{m}} instruction pattern | |
3f30a9a6 RH |
5238 | @cindex @code{vec_widen_umult_even_@var{m}} instruction pattern |
5239 | @cindex @code{vec_widen_umult_odd_@var{m}} instruction pattern | |
5240 | @cindex @code{vec_widen_smult_even_@var{m}} instruction pattern | |
5241 | @cindex @code{vec_widen_smult_odd_@var{m}} instruction pattern | |
d9987fb4 UB |
5242 | @item @samp{vec_widen_umult_hi_@var{m}}, @samp{vec_widen_umult_lo_@var{m}} |
5243 | @itemx @samp{vec_widen_smult_hi_@var{m}}, @samp{vec_widen_smult_lo_@var{m}} | |
3f30a9a6 RH |
5244 | @itemx @samp{vec_widen_umult_even_@var{m}}, @samp{vec_widen_umult_odd_@var{m}} |
5245 | @itemx @samp{vec_widen_smult_even_@var{m}}, @samp{vec_widen_smult_odd_@var{m}} | |
8115817b | 5246 | Signed/Unsigned widening multiplication. The two inputs (operands 1 and 2) |
0ee2ea09 | 5247 | are vectors with N signed/unsigned elements of size S@. Multiply the high/low |
3f30a9a6 | 5248 | or even/odd elements of the two vectors, and put the N/2 products of size 2*S |
4a271b7e BM |
5249 | in the output vector (operand 0). A target shouldn't implement even/odd pattern |
5250 | pair if it is less efficient than lo/hi one. | |
89d67cca | 5251 | |
36ba4aae IR |
5252 | @cindex @code{vec_widen_ushiftl_hi_@var{m}} instruction pattern |
5253 | @cindex @code{vec_widen_ushiftl_lo_@var{m}} instruction pattern | |
5254 | @cindex @code{vec_widen_sshiftl_hi_@var{m}} instruction pattern | |
5255 | @cindex @code{vec_widen_sshiftl_lo_@var{m}} instruction pattern | |
5256 | @item @samp{vec_widen_ushiftl_hi_@var{m}}, @samp{vec_widen_ushiftl_lo_@var{m}} | |
5257 | @itemx @samp{vec_widen_sshiftl_hi_@var{m}}, @samp{vec_widen_sshiftl_lo_@var{m}} | |
5258 | Signed/Unsigned widening shift left. The first input (operand 1) is a vector | |
5259 | with N signed/unsigned elements of size S@. Operand 2 is a constant. Shift | |
5260 | the high/low elements of operand 1, and put the N/2 results of size 2*S in the | |
5261 | output vector (operand 0). | |
5262 | ||
03dda8e3 RK |
5263 | @cindex @code{mulhisi3} instruction pattern |
5264 | @item @samp{mulhisi3} | |
5265 | Multiply operands 1 and 2, which have mode @code{HImode}, and store | |
5266 | a @code{SImode} product in operand 0. | |
5267 | ||
5268 | @cindex @code{mulqihi3} instruction pattern | |
5269 | @cindex @code{mulsidi3} instruction pattern | |
5270 | @item @samp{mulqihi3}, @samp{mulsidi3} | |
5271 | Similar widening-multiplication instructions of other widths. | |
5272 | ||
5273 | @cindex @code{umulqihi3} instruction pattern | |
5274 | @cindex @code{umulhisi3} instruction pattern | |
5275 | @cindex @code{umulsidi3} instruction pattern | |
5276 | @item @samp{umulqihi3}, @samp{umulhisi3}, @samp{umulsidi3} | |
5277 | Similar widening-multiplication instructions that do unsigned | |
5278 | multiplication. | |
5279 | ||
8b44057d BS |
5280 | @cindex @code{usmulqihi3} instruction pattern |
5281 | @cindex @code{usmulhisi3} instruction pattern | |
5282 | @cindex @code{usmulsidi3} instruction pattern | |
5283 | @item @samp{usmulqihi3}, @samp{usmulhisi3}, @samp{usmulsidi3} | |
5284 | Similar widening-multiplication instructions that interpret the first | |
5285 | operand as unsigned and the second operand as signed, then do a signed | |
5286 | multiplication. | |
5287 | ||
03dda8e3 | 5288 | @cindex @code{smul@var{m}3_highpart} instruction pattern |
759c58af | 5289 | @item @samp{smul@var{m}3_highpart} |
03dda8e3 RK |
5290 | Perform a signed multiplication of operands 1 and 2, which have mode |
5291 | @var{m}, and store the most significant half of the product in operand 0. | |
5292 | The least significant half of the product is discarded. | |
5293 | ||
5294 | @cindex @code{umul@var{m}3_highpart} instruction pattern | |
5295 | @item @samp{umul@var{m}3_highpart} | |
5296 | Similar, but the multiplication is unsigned. | |
5297 | ||
7f9844ca RS |
5298 | @cindex @code{madd@var{m}@var{n}4} instruction pattern |
5299 | @item @samp{madd@var{m}@var{n}4} | |
5300 | Multiply operands 1 and 2, sign-extend them to mode @var{n}, add | |
5301 | operand 3, and store the result in operand 0. Operands 1 and 2 | |
5302 | have mode @var{m} and operands 0 and 3 have mode @var{n}. | |
0f996086 | 5303 | Both modes must be integer or fixed-point modes and @var{n} must be twice |
7f9844ca RS |
5304 | the size of @var{m}. |
5305 | ||
5306 | In other words, @code{madd@var{m}@var{n}4} is like | |
5307 | @code{mul@var{m}@var{n}3} except that it also adds operand 3. | |
5308 | ||
5309 | These instructions are not allowed to @code{FAIL}. | |
5310 | ||
5311 | @cindex @code{umadd@var{m}@var{n}4} instruction pattern | |
5312 | @item @samp{umadd@var{m}@var{n}4} | |
5313 | Like @code{madd@var{m}@var{n}4}, but zero-extend the multiplication | |
5314 | operands instead of sign-extending them. | |
5315 | ||
0f996086 CF |
5316 | @cindex @code{ssmadd@var{m}@var{n}4} instruction pattern |
5317 | @item @samp{ssmadd@var{m}@var{n}4} | |
5318 | Like @code{madd@var{m}@var{n}4}, but all involved operations must be | |
5319 | signed-saturating. | |
5320 | ||
5321 | @cindex @code{usmadd@var{m}@var{n}4} instruction pattern | |
5322 | @item @samp{usmadd@var{m}@var{n}4} | |
5323 | Like @code{umadd@var{m}@var{n}4}, but all involved operations must be | |
5324 | unsigned-saturating. | |
5325 | ||
14661f36 CF |
5326 | @cindex @code{msub@var{m}@var{n}4} instruction pattern |
5327 | @item @samp{msub@var{m}@var{n}4} | |
5328 | Multiply operands 1 and 2, sign-extend them to mode @var{n}, subtract the | |
5329 | result from operand 3, and store the result in operand 0. Operands 1 and 2 | |
5330 | have mode @var{m} and operands 0 and 3 have mode @var{n}. | |
0f996086 | 5331 | Both modes must be integer or fixed-point modes and @var{n} must be twice |
14661f36 CF |
5332 | the size of @var{m}. |
5333 | ||
5334 | In other words, @code{msub@var{m}@var{n}4} is like | |
5335 | @code{mul@var{m}@var{n}3} except that it also subtracts the result | |
5336 | from operand 3. | |
5337 | ||
5338 | These instructions are not allowed to @code{FAIL}. | |
5339 | ||
5340 | @cindex @code{umsub@var{m}@var{n}4} instruction pattern | |
5341 | @item @samp{umsub@var{m}@var{n}4} | |
5342 | Like @code{msub@var{m}@var{n}4}, but zero-extend the multiplication | |
5343 | operands instead of sign-extending them. | |
5344 | ||
0f996086 CF |
5345 | @cindex @code{ssmsub@var{m}@var{n}4} instruction pattern |
5346 | @item @samp{ssmsub@var{m}@var{n}4} | |
5347 | Like @code{msub@var{m}@var{n}4}, but all involved operations must be | |
5348 | signed-saturating. | |
5349 | ||
5350 | @cindex @code{usmsub@var{m}@var{n}4} instruction pattern | |
5351 | @item @samp{usmsub@var{m}@var{n}4} | |
5352 | Like @code{umsub@var{m}@var{n}4}, but all involved operations must be | |
5353 | unsigned-saturating. | |
5354 | ||
03dda8e3 RK |
5355 | @cindex @code{divmod@var{m}4} instruction pattern |
5356 | @item @samp{divmod@var{m}4} | |
5357 | Signed division that produces both a quotient and a remainder. | |
5358 | Operand 1 is divided by operand 2 to produce a quotient stored | |
5359 | in operand 0 and a remainder stored in operand 3. | |
5360 | ||
5361 | For machines with an instruction that produces both a quotient and a | |
5362 | remainder, provide a pattern for @samp{divmod@var{m}4} but do not | |
5363 | provide patterns for @samp{div@var{m}3} and @samp{mod@var{m}3}. This | |
5364 | allows optimization in the relatively common case when both the quotient | |
5365 | and remainder are computed. | |
5366 | ||
5367 | If an instruction that just produces a quotient or just a remainder | |
5368 | exists and is more efficient than the instruction that produces both, | |
5369 | write the output routine of @samp{divmod@var{m}4} to call | |
5370 | @code{find_reg_note} and look for a @code{REG_UNUSED} note on the | |
5371 | quotient or remainder and generate the appropriate instruction. | |
5372 | ||
5373 | @cindex @code{udivmod@var{m}4} instruction pattern | |
5374 | @item @samp{udivmod@var{m}4} | |
5375 | Similar, but does unsigned division. | |
5376 | ||
273a2526 | 5377 | @anchor{shift patterns} |
03dda8e3 | 5378 | @cindex @code{ashl@var{m}3} instruction pattern |
0f996086 CF |
5379 | @cindex @code{ssashl@var{m}3} instruction pattern |
5380 | @cindex @code{usashl@var{m}3} instruction pattern | |
5381 | @item @samp{ashl@var{m}3}, @samp{ssashl@var{m}3}, @samp{usashl@var{m}3} | |
03dda8e3 RK |
5382 | Arithmetic-shift operand 1 left by a number of bits specified by operand |
5383 | 2, and store the result in operand 0. Here @var{m} is the mode of | |
5384 | operand 0 and operand 1; operand 2's mode is specified by the | |
5385 | instruction pattern, and the compiler will convert the operand to that | |
78250306 JJ |
5386 | mode before generating the instruction. The shift or rotate expander |
5387 | or instruction pattern should explicitly specify the mode of the operand 2, | |
5388 | it should never be @code{VOIDmode}. The meaning of out-of-range shift | |
273a2526 | 5389 | counts can optionally be specified by @code{TARGET_SHIFT_TRUNCATION_MASK}. |
71d46ca5 | 5390 | @xref{TARGET_SHIFT_TRUNCATION_MASK}. Operand 2 is always a scalar type. |
03dda8e3 RK |
5391 | |
5392 | @cindex @code{ashr@var{m}3} instruction pattern | |
5393 | @cindex @code{lshr@var{m}3} instruction pattern | |
5394 | @cindex @code{rotl@var{m}3} instruction pattern | |
5395 | @cindex @code{rotr@var{m}3} instruction pattern | |
5396 | @item @samp{ashr@var{m}3}, @samp{lshr@var{m}3}, @samp{rotl@var{m}3}, @samp{rotr@var{m}3} | |
5397 | Other shift and rotate instructions, analogous to the | |
71d46ca5 MM |
5398 | @code{ashl@var{m}3} instructions. Operand 2 is always a scalar type. |
5399 | ||
5400 | @cindex @code{vashl@var{m}3} instruction pattern | |
5401 | @cindex @code{vashr@var{m}3} instruction pattern | |
5402 | @cindex @code{vlshr@var{m}3} instruction pattern | |
5403 | @cindex @code{vrotl@var{m}3} instruction pattern | |
5404 | @cindex @code{vrotr@var{m}3} instruction pattern | |
5405 | @item @samp{vashl@var{m}3}, @samp{vashr@var{m}3}, @samp{vlshr@var{m}3}, @samp{vrotl@var{m}3}, @samp{vrotr@var{m}3} | |
5406 | Vector shift and rotate instructions that take vectors as operand 2 | |
5407 | instead of a scalar type. | |
03dda8e3 | 5408 | |
ac868f29 EB |
5409 | @cindex @code{bswap@var{m}2} instruction pattern |
5410 | @item @samp{bswap@var{m}2} | |
5411 | Reverse the order of bytes of operand 1 and store the result in operand 0. | |
5412 | ||
03dda8e3 | 5413 | @cindex @code{neg@var{m}2} instruction pattern |
0f996086 CF |
5414 | @cindex @code{ssneg@var{m}2} instruction pattern |
5415 | @cindex @code{usneg@var{m}2} instruction pattern | |
5416 | @item @samp{neg@var{m}2}, @samp{ssneg@var{m}2}, @samp{usneg@var{m}2} | |
03dda8e3 RK |
5417 | Negate operand 1 and store the result in operand 0. |
5418 | ||
481efdd9 EB |
5419 | @cindex @code{negv@var{m}3} instruction pattern |
5420 | @item @samp{negv@var{m}3} | |
5421 | Like @code{neg@var{m}2} but takes a @code{code_label} as operand 2 and | |
5422 | emits code to jump to it if signed overflow occurs during the negation. | |
5423 | ||
03dda8e3 RK |
5424 | @cindex @code{abs@var{m}2} instruction pattern |
5425 | @item @samp{abs@var{m}2} | |
5426 | Store the absolute value of operand 1 into operand 0. | |
5427 | ||
5428 | @cindex @code{sqrt@var{m}2} instruction pattern | |
5429 | @item @samp{sqrt@var{m}2} | |
a54a5997 RS |
5430 | Store the square root of operand 1 into operand 0. Both operands have |
5431 | mode @var{m}, which is a scalar or vector floating-point mode. | |
03dda8e3 | 5432 | |
a54a5997 | 5433 | This pattern is not allowed to @code{FAIL}. |
e7b489c8 | 5434 | |
ee62a5a6 RS |
5435 | @cindex @code{rsqrt@var{m}2} instruction pattern |
5436 | @item @samp{rsqrt@var{m}2} | |
5437 | Store the reciprocal of the square root of operand 1 into operand 0. | |
a54a5997 RS |
5438 | Both operands have mode @var{m}, which is a scalar or vector |
5439 | floating-point mode. | |
5440 | ||
ee62a5a6 RS |
5441 | On most architectures this pattern is only approximate, so either |
5442 | its C condition or the @code{TARGET_OPTAB_SUPPORTED_P} hook should | |
5443 | check for the appropriate math flags. (Using the C condition is | |
5444 | more direct, but using @code{TARGET_OPTAB_SUPPORTED_P} can be useful | |
5445 | if a target-specific built-in also uses the @samp{rsqrt@var{m}2} | |
5446 | pattern.) | |
5447 | ||
5448 | This pattern is not allowed to @code{FAIL}. | |
5449 | ||
17b98269 UB |
5450 | @cindex @code{fmod@var{m}3} instruction pattern |
5451 | @item @samp{fmod@var{m}3} | |
5452 | Store the remainder of dividing operand 1 by operand 2 into | |
a54a5997 RS |
5453 | operand 0, rounded towards zero to an integer. All operands have |
5454 | mode @var{m}, which is a scalar or vector floating-point mode. | |
17b98269 | 5455 | |
a54a5997 | 5456 | This pattern is not allowed to @code{FAIL}. |
17b98269 UB |
5457 | |
5458 | @cindex @code{remainder@var{m}3} instruction pattern | |
5459 | @item @samp{remainder@var{m}3} | |
5460 | Store the remainder of dividing operand 1 by operand 2 into | |
a54a5997 RS |
5461 | operand 0, rounded to the nearest integer. All operands have |
5462 | mode @var{m}, which is a scalar or vector floating-point mode. | |
5463 | ||
5464 | This pattern is not allowed to @code{FAIL}. | |
5465 | ||
5466 | @cindex @code{scalb@var{m}3} instruction pattern | |
5467 | @item @samp{scalb@var{m}3} | |
5468 | Raise @code{FLT_RADIX} to the power of operand 2, multiply it by | |
5469 | operand 1, and store the result in operand 0. All operands have | |
5470 | mode @var{m}, which is a scalar or vector floating-point mode. | |
17b98269 | 5471 | |
a54a5997 RS |
5472 | This pattern is not allowed to @code{FAIL}. |
5473 | ||
5474 | @cindex @code{ldexp@var{m}3} instruction pattern | |
5475 | @item @samp{ldexp@var{m}3} | |
5476 | Raise 2 to the power of operand 2, multiply it by operand 1, and store | |
5477 | the result in operand 0. Operands 0 and 1 have mode @var{m}, which is | |
5478 | a scalar or vector floating-point mode. Operand 2's mode has | |
5479 | the same number of elements as @var{m} and each element is wide | |
5480 | enough to store an @code{int}. The integers are signed. | |
5481 | ||
5482 | This pattern is not allowed to @code{FAIL}. | |
17b98269 | 5483 | |
e7b489c8 RS |
5484 | @cindex @code{cos@var{m}2} instruction pattern |
5485 | @item @samp{cos@var{m}2} | |
a54a5997 RS |
5486 | Store the cosine of operand 1 into operand 0. Both operands have |
5487 | mode @var{m}, which is a scalar or vector floating-point mode. | |
e7b489c8 | 5488 | |
a54a5997 | 5489 | This pattern is not allowed to @code{FAIL}. |
e7b489c8 RS |
5490 | |
5491 | @cindex @code{sin@var{m}2} instruction pattern | |
5492 | @item @samp{sin@var{m}2} | |
a54a5997 RS |
5493 | Store the sine of operand 1 into operand 0. Both operands have |
5494 | mode @var{m}, which is a scalar or vector floating-point mode. | |
e7b489c8 | 5495 | |
a54a5997 | 5496 | This pattern is not allowed to @code{FAIL}. |
e7b489c8 | 5497 | |
6d1f6aff OE |
5498 | @cindex @code{sincos@var{m}3} instruction pattern |
5499 | @item @samp{sincos@var{m}3} | |
6ba9e401 | 5500 | Store the cosine of operand 2 into operand 0 and the sine of |
a54a5997 RS |
5501 | operand 2 into operand 1. All operands have mode @var{m}, |
5502 | which is a scalar or vector floating-point mode. | |
6d1f6aff | 5503 | |
6d1f6aff OE |
5504 | Targets that can calculate the sine and cosine simultaneously can |
5505 | implement this pattern as opposed to implementing individual | |
5506 | @code{sin@var{m}2} and @code{cos@var{m}2} patterns. The @code{sin} | |
5507 | and @code{cos} built-in functions will then be expanded to the | |
5508 | @code{sincos@var{m}3} pattern, with one of the output values | |
5509 | left unused. | |
5510 | ||
a54a5997 RS |
5511 | @cindex @code{tan@var{m}2} instruction pattern |
5512 | @item @samp{tan@var{m}2} | |
5513 | Store the tangent of operand 1 into operand 0. Both operands have | |
5514 | mode @var{m}, which is a scalar or vector floating-point mode. | |
5515 | ||
5516 | This pattern is not allowed to @code{FAIL}. | |
5517 | ||
5518 | @cindex @code{asin@var{m}2} instruction pattern | |
5519 | @item @samp{asin@var{m}2} | |
5520 | Store the arc sine of operand 1 into operand 0. Both operands have | |
5521 | mode @var{m}, which is a scalar or vector floating-point mode. | |
5522 | ||
5523 | This pattern is not allowed to @code{FAIL}. | |
5524 | ||
5525 | @cindex @code{acos@var{m}2} instruction pattern | |
5526 | @item @samp{acos@var{m}2} | |
5527 | Store the arc cosine of operand 1 into operand 0. Both operands have | |
5528 | mode @var{m}, which is a scalar or vector floating-point mode. | |
5529 | ||
5530 | This pattern is not allowed to @code{FAIL}. | |
5531 | ||
5532 | @cindex @code{atan@var{m}2} instruction pattern | |
5533 | @item @samp{atan@var{m}2} | |
5534 | Store the arc tangent of operand 1 into operand 0. Both operands have | |
5535 | mode @var{m}, which is a scalar or vector floating-point mode. | |
5536 | ||
5537 | This pattern is not allowed to @code{FAIL}. | |
5538 | ||
e7b489c8 RS |
5539 | @cindex @code{exp@var{m}2} instruction pattern |
5540 | @item @samp{exp@var{m}2} | |
a54a5997 RS |
5541 | Raise e (the base of natural logarithms) to the power of operand 1 |
5542 | and store the result in operand 0. Both operands have mode @var{m}, | |
5543 | which is a scalar or vector floating-point mode. | |
5544 | ||
5545 | This pattern is not allowed to @code{FAIL}. | |
5546 | ||
5547 | @cindex @code{expm1@var{m}2} instruction pattern | |
5548 | @item @samp{expm1@var{m}2} | |
5549 | Raise e (the base of natural logarithms) to the power of operand 1, | |
5550 | subtract 1, and store the result in operand 0. Both operands have | |
5551 | mode @var{m}, which is a scalar or vector floating-point mode. | |
5552 | ||
5553 | For inputs close to zero, the pattern is expected to be more | |
5554 | accurate than a separate @code{exp@var{m}2} and @code{sub@var{m}3} | |
5555 | would be. | |
5556 | ||
5557 | This pattern is not allowed to @code{FAIL}. | |
5558 | ||
5559 | @cindex @code{exp10@var{m}2} instruction pattern | |
5560 | @item @samp{exp10@var{m}2} | |
5561 | Raise 10 to the power of operand 1 and store the result in operand 0. | |
5562 | Both operands have mode @var{m}, which is a scalar or vector | |
5563 | floating-point mode. | |
5564 | ||
5565 | This pattern is not allowed to @code{FAIL}. | |
5566 | ||
5567 | @cindex @code{exp2@var{m}2} instruction pattern | |
5568 | @item @samp{exp2@var{m}2} | |
5569 | Raise 2 to the power of operand 1 and store the result in operand 0. | |
5570 | Both operands have mode @var{m}, which is a scalar or vector | |
5571 | floating-point mode. | |
e7b489c8 | 5572 | |
a54a5997 | 5573 | This pattern is not allowed to @code{FAIL}. |
e7b489c8 RS |
5574 | |
5575 | @cindex @code{log@var{m}2} instruction pattern | |
5576 | @item @samp{log@var{m}2} | |
a54a5997 RS |
5577 | Store the natural logarithm of operand 1 into operand 0. Both operands |
5578 | have mode @var{m}, which is a scalar or vector floating-point mode. | |
5579 | ||
5580 | This pattern is not allowed to @code{FAIL}. | |
5581 | ||
5582 | @cindex @code{log1p@var{m}2} instruction pattern | |
5583 | @item @samp{log1p@var{m}2} | |
5584 | Add 1 to operand 1, compute the natural logarithm, and store | |
5585 | the result in operand 0. Both operands have mode @var{m}, which is | |
5586 | a scalar or vector floating-point mode. | |
5587 | ||
5588 | For inputs close to zero, the pattern is expected to be more | |
5589 | accurate than a separate @code{add@var{m}3} and @code{log@var{m}2} | |
5590 | would be. | |
5591 | ||
5592 | This pattern is not allowed to @code{FAIL}. | |
5593 | ||
5594 | @cindex @code{log10@var{m}2} instruction pattern | |
5595 | @item @samp{log10@var{m}2} | |
5596 | Store the base-10 logarithm of operand 1 into operand 0. Both operands | |
5597 | have mode @var{m}, which is a scalar or vector floating-point mode. | |
5598 | ||
5599 | This pattern is not allowed to @code{FAIL}. | |
5600 | ||
5601 | @cindex @code{log2@var{m}2} instruction pattern | |
5602 | @item @samp{log2@var{m}2} | |
5603 | Store the base-2 logarithm of operand 1 into operand 0. Both operands | |
5604 | have mode @var{m}, which is a scalar or vector floating-point mode. | |
e7b489c8 | 5605 | |
a54a5997 RS |
5606 | This pattern is not allowed to @code{FAIL}. |
5607 | ||
5608 | @cindex @code{logb@var{m}2} instruction pattern | |
5609 | @item @samp{logb@var{m}2} | |
5610 | Store the base-@code{FLT_RADIX} logarithm of operand 1 into operand 0. | |
5611 | Both operands have mode @var{m}, which is a scalar or vector | |
5612 | floating-point mode. | |
5613 | ||
5614 | This pattern is not allowed to @code{FAIL}. | |
5615 | ||
5616 | @cindex @code{significand@var{m}2} instruction pattern | |
5617 | @item @samp{significand@var{m}2} | |
5618 | Store the significand of floating-point operand 1 in operand 0. | |
5619 | Both operands have mode @var{m}, which is a scalar or vector | |
5620 | floating-point mode. | |
5621 | ||
5622 | This pattern is not allowed to @code{FAIL}. | |
03dda8e3 | 5623 | |
b5e01d4b RS |
5624 | @cindex @code{pow@var{m}3} instruction pattern |
5625 | @item @samp{pow@var{m}3} | |
5626 | Store the value of operand 1 raised to the exponent operand 2 | |
a54a5997 RS |
5627 | into operand 0. All operands have mode @var{m}, which is a scalar |
5628 | or vector floating-point mode. | |
b5e01d4b | 5629 | |
a54a5997 | 5630 | This pattern is not allowed to @code{FAIL}. |
b5e01d4b RS |
5631 | |
5632 | @cindex @code{atan2@var{m}3} instruction pattern | |
5633 | @item @samp{atan2@var{m}3} | |
5634 | Store the arc tangent (inverse tangent) of operand 1 divided by | |
5635 | operand 2 into operand 0, using the signs of both arguments to | |
a54a5997 RS |
5636 | determine the quadrant of the result. All operands have mode |
5637 | @var{m}, which is a scalar or vector floating-point mode. | |
b5e01d4b | 5638 | |
a54a5997 | 5639 | This pattern is not allowed to @code{FAIL}. |
b5e01d4b | 5640 | |
4977bab6 ZW |
5641 | @cindex @code{floor@var{m}2} instruction pattern |
5642 | @item @samp{floor@var{m}2} | |
a54a5997 RS |
5643 | Store the largest integral value not greater than operand 1 in operand 0. |
5644 | Both operands have mode @var{m}, which is a scalar or vector | |
0d2f700f JM |
5645 | floating-point mode. If @option{-ffp-int-builtin-inexact} is in |
5646 | effect, the ``inexact'' exception may be raised for noninteger | |
5647 | operands; otherwise, it may not. | |
4977bab6 | 5648 | |
a54a5997 | 5649 | This pattern is not allowed to @code{FAIL}. |
4977bab6 | 5650 | |
10553f10 UB |
5651 | @cindex @code{btrunc@var{m}2} instruction pattern |
5652 | @item @samp{btrunc@var{m}2} | |
a54a5997 RS |
5653 | Round operand 1 to an integer, towards zero, and store the result in |
5654 | operand 0. Both operands have mode @var{m}, which is a scalar or | |
0d2f700f JM |
5655 | vector floating-point mode. If @option{-ffp-int-builtin-inexact} is |
5656 | in effect, the ``inexact'' exception may be raised for noninteger | |
5657 | operands; otherwise, it may not. | |
4977bab6 | 5658 | |
a54a5997 | 5659 | This pattern is not allowed to @code{FAIL}. |
4977bab6 ZW |
5660 | |
5661 | @cindex @code{round@var{m}2} instruction pattern | |
5662 | @item @samp{round@var{m}2} | |
a54a5997 RS |
5663 | Round operand 1 to the nearest integer, rounding away from zero in the |
5664 | event of a tie, and store the result in operand 0. Both operands have | |
0d2f700f JM |
5665 | mode @var{m}, which is a scalar or vector floating-point mode. If |
5666 | @option{-ffp-int-builtin-inexact} is in effect, the ``inexact'' | |
5667 | exception may be raised for noninteger operands; otherwise, it may | |
5668 | not. | |
4977bab6 | 5669 | |
a54a5997 | 5670 | This pattern is not allowed to @code{FAIL}. |
4977bab6 ZW |
5671 | |
5672 | @cindex @code{ceil@var{m}2} instruction pattern | |
5673 | @item @samp{ceil@var{m}2} | |
a54a5997 RS |
5674 | Store the smallest integral value not less than operand 1 in operand 0. |
5675 | Both operands have mode @var{m}, which is a scalar or vector | |
0d2f700f JM |
5676 | floating-point mode. If @option{-ffp-int-builtin-inexact} is in |
5677 | effect, the ``inexact'' exception may be raised for noninteger | |
5678 | operands; otherwise, it may not. | |
4977bab6 | 5679 | |
a54a5997 | 5680 | This pattern is not allowed to @code{FAIL}. |
4977bab6 ZW |
5681 | |
5682 | @cindex @code{nearbyint@var{m}2} instruction pattern | |
5683 | @item @samp{nearbyint@var{m}2} | |
a54a5997 RS |
5684 | Round operand 1 to an integer, using the current rounding mode, and |
5685 | store the result in operand 0. Do not raise an inexact condition when | |
5686 | the result is different from the argument. Both operands have mode | |
5687 | @var{m}, which is a scalar or vector floating-point mode. | |
4977bab6 | 5688 | |
a54a5997 | 5689 | This pattern is not allowed to @code{FAIL}. |
4977bab6 | 5690 | |
10553f10 UB |
5691 | @cindex @code{rint@var{m}2} instruction pattern |
5692 | @item @samp{rint@var{m}2} | |
a54a5997 RS |
5693 | Round operand 1 to an integer, using the current rounding mode, and |
5694 | store the result in operand 0. Raise an inexact condition when | |
5695 | the result is different from the argument. Both operands have mode | |
5696 | @var{m}, which is a scalar or vector floating-point mode. | |
10553f10 | 5697 | |
a54a5997 | 5698 | This pattern is not allowed to @code{FAIL}. |
10553f10 | 5699 | |
bb7f0423 RG |
5700 | @cindex @code{lrint@var{m}@var{n}2} |
5701 | @item @samp{lrint@var{m}@var{n}2} | |
5702 | Convert operand 1 (valid for floating point mode @var{m}) to fixed | |
5703 | point mode @var{n} as a signed number according to the current | |
5704 | rounding mode and store in operand 0 (which has mode @var{n}). | |
5705 | ||
4d81bf84 | 5706 | @cindex @code{lround@var{m}@var{n}2} |
e0d4c0b3 | 5707 | @item @samp{lround@var{m}@var{n}2} |
4d81bf84 RG |
5708 | Convert operand 1 (valid for floating point mode @var{m}) to fixed |
5709 | point mode @var{n} as a signed number rounding to nearest and away | |
5710 | from zero and store in operand 0 (which has mode @var{n}). | |
5711 | ||
c3a4177f | 5712 | @cindex @code{lfloor@var{m}@var{n}2} |
e0d4c0b3 | 5713 | @item @samp{lfloor@var{m}@var{n}2} |
c3a4177f RG |
5714 | Convert operand 1 (valid for floating point mode @var{m}) to fixed |
5715 | point mode @var{n} as a signed number rounding down and store in | |
5716 | operand 0 (which has mode @var{n}). | |
5717 | ||
5718 | @cindex @code{lceil@var{m}@var{n}2} | |
e0d4c0b3 | 5719 | @item @samp{lceil@var{m}@var{n}2} |
c3a4177f RG |
5720 | Convert operand 1 (valid for floating point mode @var{m}) to fixed |
5721 | point mode @var{n} as a signed number rounding up and store in | |
5722 | operand 0 (which has mode @var{n}). | |
5723 | ||
d35a40fc DE |
5724 | @cindex @code{copysign@var{m}3} instruction pattern |
5725 | @item @samp{copysign@var{m}3} | |
5726 | Store a value with the magnitude of operand 1 and the sign of operand | |
a54a5997 RS |
5727 | 2 into operand 0. All operands have mode @var{m}, which is a scalar or |
5728 | vector floating-point mode. | |
d35a40fc | 5729 | |
a54a5997 | 5730 | This pattern is not allowed to @code{FAIL}. |
d35a40fc | 5731 | |
03dda8e3 RK |
5732 | @cindex @code{ffs@var{m}2} instruction pattern |
5733 | @item @samp{ffs@var{m}2} | |
5734 | Store into operand 0 one plus the index of the least significant 1-bit | |
a54a5997 | 5735 | of operand 1. If operand 1 is zero, store zero. |
03dda8e3 | 5736 | |
a54a5997 RS |
5737 | @var{m} is either a scalar or vector integer mode. When it is a scalar, |
5738 | operand 1 has mode @var{m} but operand 0 can have whatever scalar | |
5739 | integer mode is suitable for the target. The compiler will insert | |
5740 | conversion instructions as necessary (typically to convert the result | |
5741 | to the same width as @code{int}). When @var{m} is a vector, both | |
5742 | operands must have mode @var{m}. | |
5743 | ||
5744 | This pattern is not allowed to @code{FAIL}. | |
03dda8e3 | 5745 | |
e7a45277 KT |
5746 | @cindex @code{clrsb@var{m}2} instruction pattern |
5747 | @item @samp{clrsb@var{m}2} | |
5748 | Count leading redundant sign bits. | |
5749 | Store into operand 0 the number of redundant sign bits in operand 1, starting | |
5750 | at the most significant bit position. | |
5751 | A redundant sign bit is defined as any sign bit after the first. As such, | |
5752 | this count will be one less than the count of leading sign bits. | |
5753 | ||
a54a5997 RS |
5754 | @var{m} is either a scalar or vector integer mode. When it is a scalar, |
5755 | operand 1 has mode @var{m} but operand 0 can have whatever scalar | |
5756 | integer mode is suitable for the target. The compiler will insert | |
5757 | conversion instructions as necessary (typically to convert the result | |
5758 | to the same width as @code{int}). When @var{m} is a vector, both | |
5759 | operands must have mode @var{m}. | |
5760 | ||
5761 | This pattern is not allowed to @code{FAIL}. | |
5762 | ||
2928cd7a RH |
5763 | @cindex @code{clz@var{m}2} instruction pattern |
5764 | @item @samp{clz@var{m}2} | |
e7a45277 KT |
5765 | Store into operand 0 the number of leading 0-bits in operand 1, starting |
5766 | at the most significant bit position. If operand 1 is 0, the | |
2a6627c2 JN |
5767 | @code{CLZ_DEFINED_VALUE_AT_ZERO} (@pxref{Misc}) macro defines if |
5768 | the result is undefined or has a useful value. | |
a54a5997 RS |
5769 | |
5770 | @var{m} is either a scalar or vector integer mode. When it is a scalar, | |
5771 | operand 1 has mode @var{m} but operand 0 can have whatever scalar | |
5772 | integer mode is suitable for the target. The compiler will insert | |
5773 | conversion instructions as necessary (typically to convert the result | |
5774 | to the same width as @code{int}). When @var{m} is a vector, both | |
5775 | operands must have mode @var{m}. | |
5776 | ||
5777 | This pattern is not allowed to @code{FAIL}. | |
2928cd7a RH |
5778 | |
5779 | @cindex @code{ctz@var{m}2} instruction pattern | |
5780 | @item @samp{ctz@var{m}2} | |
e7a45277 KT |
5781 | Store into operand 0 the number of trailing 0-bits in operand 1, starting |
5782 | at the least significant bit position. If operand 1 is 0, the | |
2a6627c2 JN |
5783 | @code{CTZ_DEFINED_VALUE_AT_ZERO} (@pxref{Misc}) macro defines if |
5784 | the result is undefined or has a useful value. | |
a54a5997 RS |
5785 | |
5786 | @var{m} is either a scalar or vector integer mode. When it is a scalar, | |
5787 | operand 1 has mode @var{m} but operand 0 can have whatever scalar | |
5788 | integer mode is suitable for the target. The compiler will insert | |
5789 | conversion instructions as necessary (typically to convert the result | |
5790 | to the same width as @code{int}). When @var{m} is a vector, both | |
5791 | operands must have mode @var{m}. | |
5792 | ||
5793 | This pattern is not allowed to @code{FAIL}. | |
2928cd7a RH |
5794 | |
5795 | @cindex @code{popcount@var{m}2} instruction pattern | |
5796 | @item @samp{popcount@var{m}2} | |
a54a5997 RS |
5797 | Store into operand 0 the number of 1-bits in operand 1. |
5798 | ||
5799 | @var{m} is either a scalar or vector integer mode. When it is a scalar, | |
5800 | operand 1 has mode @var{m} but operand 0 can have whatever scalar | |
5801 | integer mode is suitable for the target. The compiler will insert | |
5802 | conversion instructions as necessary (typically to convert the result | |
5803 | to the same width as @code{int}). When @var{m} is a vector, both | |
5804 | operands must have mode @var{m}. | |
5805 | ||
5806 | This pattern is not allowed to @code{FAIL}. | |
2928cd7a RH |
5807 | |
5808 | @cindex @code{parity@var{m}2} instruction pattern | |
5809 | @item @samp{parity@var{m}2} | |
e7a45277 | 5810 | Store into operand 0 the parity of operand 1, i.e.@: the number of 1-bits |
a54a5997 RS |
5811 | in operand 1 modulo 2. |
5812 | ||
5813 | @var{m} is either a scalar or vector integer mode. When it is a scalar, | |
5814 | operand 1 has mode @var{m} but operand 0 can have whatever scalar | |
5815 | integer mode is suitable for the target. The compiler will insert | |
5816 | conversion instructions as necessary (typically to convert the result | |
5817 | to the same width as @code{int}). When @var{m} is a vector, both | |
5818 | operands must have mode @var{m}. | |
5819 | ||
5820 | This pattern is not allowed to @code{FAIL}. | |
2928cd7a | 5821 | |
03dda8e3 RK |
5822 | @cindex @code{one_cmpl@var{m}2} instruction pattern |
5823 | @item @samp{one_cmpl@var{m}2} | |
5824 | Store the bitwise-complement of operand 1 into operand 0. | |
5825 | ||
70128ad9 AO |
5826 | @cindex @code{movmem@var{m}} instruction pattern |
5827 | @item @samp{movmem@var{m}} | |
beed8fc0 AO |
5828 | Block move instruction. The destination and source blocks of memory |
5829 | are the first two operands, and both are @code{mem:BLK}s with an | |
5830 | address in mode @code{Pmode}. | |
e5e809f4 | 5831 | |
03dda8e3 | 5832 | The number of bytes to move is the third operand, in mode @var{m}. |
5689294c | 5833 | Usually, you specify @code{Pmode} for @var{m}. However, if you can |
e5e809f4 | 5834 | generate better code knowing the range of valid lengths is smaller than |
5689294c L |
5835 | those representable in a full Pmode pointer, you should provide |
5836 | a pattern with a | |
e5e809f4 JL |
5837 | mode corresponding to the range of values you can handle efficiently |
5838 | (e.g., @code{QImode} for values in the range 0--127; note we avoid numbers | |
5689294c | 5839 | that appear negative) and also a pattern with @code{Pmode}. |
03dda8e3 RK |
5840 | |
5841 | The fourth operand is the known shared alignment of the source and | |
5842 | destination, in the form of a @code{const_int} rtx. Thus, if the | |
5843 | compiler knows that both source and destination are word-aligned, | |
5844 | it may provide the value 4 for this operand. | |
5845 | ||
079a182e JH |
5846 | Optional operands 5 and 6 specify expected alignment and size of block |
5847 | respectively. The expected alignment differs from alignment in operand 4 | |
5848 | in a way that the blocks are not required to be aligned according to it in | |
9946ca2d RA |
5849 | all cases. This expected alignment is also in bytes, just like operand 4. |
5850 | Expected size, when unknown, is set to @code{(const_int -1)}. | |
079a182e | 5851 | |
70128ad9 | 5852 | Descriptions of multiple @code{movmem@var{m}} patterns can only be |
4693911f | 5853 | beneficial if the patterns for smaller modes have fewer restrictions |
8c01d9b6 | 5854 | on their first, second and fourth operands. Note that the mode @var{m} |
70128ad9 | 5855 | in @code{movmem@var{m}} does not impose any restriction on the mode of |
8c01d9b6 JL |
5856 | individually moved data units in the block. |
5857 | ||
03dda8e3 RK |
5858 | These patterns need not give special consideration to the possibility |
5859 | that the source and destination strings might overlap. | |
5860 | ||
beed8fc0 AO |
5861 | @cindex @code{movstr} instruction pattern |
5862 | @item @samp{movstr} | |
5863 | String copy instruction, with @code{stpcpy} semantics. Operand 0 is | |
5864 | an output operand in mode @code{Pmode}. The addresses of the | |
5865 | destination and source strings are operands 1 and 2, and both are | |
5866 | @code{mem:BLK}s with addresses in mode @code{Pmode}. The execution of | |
5867 | the expansion of this pattern should store in operand 0 the address in | |
5868 | which the @code{NUL} terminator was stored in the destination string. | |
5869 | ||
3918b108 JH |
5870 | This patern has also several optional operands that are same as in |
5871 | @code{setmem}. | |
5872 | ||
57e84f18 AS |
5873 | @cindex @code{setmem@var{m}} instruction pattern |
5874 | @item @samp{setmem@var{m}} | |
5875 | Block set instruction. The destination string is the first operand, | |
beed8fc0 | 5876 | given as a @code{mem:BLK} whose address is in mode @code{Pmode}. The |
57e84f18 AS |
5877 | number of bytes to set is the second operand, in mode @var{m}. The value to |
5878 | initialize the memory with is the third operand. Targets that only support the | |
5879 | clearing of memory should reject any value that is not the constant 0. See | |
beed8fc0 | 5880 | @samp{movmem@var{m}} for a discussion of the choice of mode. |
03dda8e3 | 5881 | |
57e84f18 | 5882 | The fourth operand is the known alignment of the destination, in the form |
03dda8e3 RK |
5883 | of a @code{const_int} rtx. Thus, if the compiler knows that the |
5884 | destination is word-aligned, it may provide the value 4 for this | |
5885 | operand. | |
5886 | ||
079a182e JH |
5887 | Optional operands 5 and 6 specify expected alignment and size of block |
5888 | respectively. The expected alignment differs from alignment in operand 4 | |
5889 | in a way that the blocks are not required to be aligned according to it in | |
9946ca2d RA |
5890 | all cases. This expected alignment is also in bytes, just like operand 4. |
5891 | Expected size, when unknown, is set to @code{(const_int -1)}. | |
3918b108 JH |
5892 | Operand 7 is the minimal size of the block and operand 8 is the |
5893 | maximal size of the block (NULL if it can not be represented as CONST_INT). | |
82bb7d4e JH |
5894 | Operand 9 is the probable maximal size (i.e. we can not rely on it for correctness, |
5895 | but it can be used for choosing proper code sequence for a given size). | |
079a182e | 5896 | |
57e84f18 | 5897 | The use for multiple @code{setmem@var{m}} is as for @code{movmem@var{m}}. |
8c01d9b6 | 5898 | |
40c1d5f8 AS |
5899 | @cindex @code{cmpstrn@var{m}} instruction pattern |
5900 | @item @samp{cmpstrn@var{m}} | |
358b8f01 | 5901 | String compare instruction, with five operands. Operand 0 is the output; |
03dda8e3 | 5902 | it has mode @var{m}. The remaining four operands are like the operands |
70128ad9 | 5903 | of @samp{movmem@var{m}}. The two memory blocks specified are compared |
5cc2f4f3 KG |
5904 | byte by byte in lexicographic order starting at the beginning of each |
5905 | string. The instruction is not allowed to prefetch more than one byte | |
5906 | at a time since either string may end in the first byte and reading past | |
5907 | that may access an invalid page or segment and cause a fault. The | |
9b0f6f5e NC |
5908 | comparison terminates early if the fetched bytes are different or if |
5909 | they are equal to zero. The effect of the instruction is to store a | |
5910 | value in operand 0 whose sign indicates the result of the comparison. | |
03dda8e3 | 5911 | |
40c1d5f8 AS |
5912 | @cindex @code{cmpstr@var{m}} instruction pattern |
5913 | @item @samp{cmpstr@var{m}} | |
5914 | String compare instruction, without known maximum length. Operand 0 is the | |
5915 | output; it has mode @var{m}. The second and third operand are the blocks of | |
5916 | memory to be compared; both are @code{mem:BLK} with an address in mode | |
5917 | @code{Pmode}. | |
5918 | ||
5919 | The fourth operand is the known shared alignment of the source and | |
5920 | destination, in the form of a @code{const_int} rtx. Thus, if the | |
5921 | compiler knows that both source and destination are word-aligned, | |
5922 | it may provide the value 4 for this operand. | |
5923 | ||
5924 | The two memory blocks specified are compared byte by byte in lexicographic | |
5925 | order starting at the beginning of each string. The instruction is not allowed | |
5926 | to prefetch more than one byte at a time since either string may end in the | |
5927 | first byte and reading past that may access an invalid page or segment and | |
9b0f6f5e NC |
5928 | cause a fault. The comparison will terminate when the fetched bytes |
5929 | are different or if they are equal to zero. The effect of the | |
5930 | instruction is to store a value in operand 0 whose sign indicates the | |
5931 | result of the comparison. | |
40c1d5f8 | 5932 | |
358b8f01 JJ |
5933 | @cindex @code{cmpmem@var{m}} instruction pattern |
5934 | @item @samp{cmpmem@var{m}} | |
5935 | Block compare instruction, with five operands like the operands | |
5936 | of @samp{cmpstr@var{m}}. The two memory blocks specified are compared | |
5937 | byte by byte in lexicographic order starting at the beginning of each | |
5938 | block. Unlike @samp{cmpstr@var{m}} the instruction can prefetch | |
9b0f6f5e NC |
5939 | any bytes in the two memory blocks. Also unlike @samp{cmpstr@var{m}} |
5940 | the comparison will not stop if both bytes are zero. The effect of | |
5941 | the instruction is to store a value in operand 0 whose sign indicates | |
5942 | the result of the comparison. | |
358b8f01 | 5943 | |
03dda8e3 RK |
5944 | @cindex @code{strlen@var{m}} instruction pattern |
5945 | @item @samp{strlen@var{m}} | |
5946 | Compute the length of a string, with three operands. | |
5947 | Operand 0 is the result (of mode @var{m}), operand 1 is | |
5948 | a @code{mem} referring to the first character of the string, | |
5949 | operand 2 is the character to search for (normally zero), | |
5950 | and operand 3 is a constant describing the known alignment | |
5951 | of the beginning of the string. | |
5952 | ||
e0d4c0b3 | 5953 | @cindex @code{float@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
5954 | @item @samp{float@var{m}@var{n}2} |
5955 | Convert signed integer operand 1 (valid for fixed point mode @var{m}) to | |
5956 | floating point mode @var{n} and store in operand 0 (which has mode | |
5957 | @var{n}). | |
5958 | ||
e0d4c0b3 | 5959 | @cindex @code{floatuns@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
5960 | @item @samp{floatuns@var{m}@var{n}2} |
5961 | Convert unsigned integer operand 1 (valid for fixed point mode @var{m}) | |
5962 | to floating point mode @var{n} and store in operand 0 (which has mode | |
5963 | @var{n}). | |
5964 | ||
e0d4c0b3 | 5965 | @cindex @code{fix@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
5966 | @item @samp{fix@var{m}@var{n}2} |
5967 | Convert operand 1 (valid for floating point mode @var{m}) to fixed | |
5968 | point mode @var{n} as a signed number and store in operand 0 (which | |
5969 | has mode @var{n}). This instruction's result is defined only when | |
5970 | the value of operand 1 is an integer. | |
5971 | ||
0e1d7f32 AH |
5972 | If the machine description defines this pattern, it also needs to |
5973 | define the @code{ftrunc} pattern. | |
5974 | ||
e0d4c0b3 | 5975 | @cindex @code{fixuns@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
5976 | @item @samp{fixuns@var{m}@var{n}2} |
5977 | Convert operand 1 (valid for floating point mode @var{m}) to fixed | |
5978 | point mode @var{n} as an unsigned number and store in operand 0 (which | |
5979 | has mode @var{n}). This instruction's result is defined only when the | |
5980 | value of operand 1 is an integer. | |
5981 | ||
5982 | @cindex @code{ftrunc@var{m}2} instruction pattern | |
5983 | @item @samp{ftrunc@var{m}2} | |
5984 | Convert operand 1 (valid for floating point mode @var{m}) to an | |
5985 | integer value, still represented in floating point mode @var{m}, and | |
5986 | store it in operand 0 (valid for floating point mode @var{m}). | |
5987 | ||
e0d4c0b3 | 5988 | @cindex @code{fix_trunc@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
5989 | @item @samp{fix_trunc@var{m}@var{n}2} |
5990 | Like @samp{fix@var{m}@var{n}2} but works for any floating point value | |
5991 | of mode @var{m} by converting the value to an integer. | |
5992 | ||
e0d4c0b3 | 5993 | @cindex @code{fixuns_trunc@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
5994 | @item @samp{fixuns_trunc@var{m}@var{n}2} |
5995 | Like @samp{fixuns@var{m}@var{n}2} but works for any floating point | |
5996 | value of mode @var{m} by converting the value to an integer. | |
5997 | ||
e0d4c0b3 | 5998 | @cindex @code{trunc@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
5999 | @item @samp{trunc@var{m}@var{n}2} |
6000 | Truncate operand 1 (valid for mode @var{m}) to mode @var{n} and | |
6001 | store in operand 0 (which has mode @var{n}). Both modes must be fixed | |
6002 | point or both floating point. | |
6003 | ||
e0d4c0b3 | 6004 | @cindex @code{extend@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
6005 | @item @samp{extend@var{m}@var{n}2} |
6006 | Sign-extend operand 1 (valid for mode @var{m}) to mode @var{n} and | |
6007 | store in operand 0 (which has mode @var{n}). Both modes must be fixed | |
6008 | point or both floating point. | |
6009 | ||
e0d4c0b3 | 6010 | @cindex @code{zero_extend@var{m}@var{n}2} instruction pattern |
03dda8e3 RK |
6011 | @item @samp{zero_extend@var{m}@var{n}2} |
6012 | Zero-extend operand 1 (valid for mode @var{m}) to mode @var{n} and | |
6013 | store in operand 0 (which has mode @var{n}). Both modes must be fixed | |
6014 | point. | |
6015 | ||
e0d4c0b3 | 6016 | @cindex @code{fract@var{m}@var{n}2} instruction pattern |
0f996086 CF |
6017 | @item @samp{fract@var{m}@var{n}2} |
6018 | Convert operand 1 of mode @var{m} to mode @var{n} and store in | |
6019 | operand 0 (which has mode @var{n}). Mode @var{m} and mode @var{n} | |
6020 | could be fixed-point to fixed-point, signed integer to fixed-point, | |
6021 | fixed-point to signed integer, floating-point to fixed-point, | |
6022 | or fixed-point to floating-point. | |
6023 | When overflows or underflows happen, the results are undefined. | |
6024 | ||
e0d4c0b3 | 6025 | @cindex @code{satfract@var{m}@var{n}2} instruction pattern |
0f996086 CF |
6026 | @item @samp{satfract@var{m}@var{n}2} |
6027 | Convert operand 1 of mode @var{m} to mode @var{n} and store in | |
6028 | operand 0 (which has mode @var{n}). Mode @var{m} and mode @var{n} | |
6029 | could be fixed-point to fixed-point, signed integer to fixed-point, | |
6030 | or floating-point to fixed-point. | |
6031 | When overflows or underflows happen, the instruction saturates the | |
6032 | results to the maximum or the minimum. | |
6033 | ||
e0d4c0b3 | 6034 | @cindex @code{fractuns@var{m}@var{n}2} instruction pattern |
0f996086 CF |
6035 | @item @samp{fractuns@var{m}@var{n}2} |
6036 | Convert operand 1 of mode @var{m} to mode @var{n} and store in | |
6037 | operand 0 (which has mode @var{n}). Mode @var{m} and mode @var{n} | |
6038 | could be unsigned integer to fixed-point, or | |
6039 | fixed-point to unsigned integer. | |
6040 | When overflows or underflows happen, the results are undefined. | |
6041 | ||
e0d4c0b3 | 6042 | @cindex @code{satfractuns@var{m}@var{n}2} instruction pattern |
0f996086 CF |
6043 | @item @samp{satfractuns@var{m}@var{n}2} |
6044 | Convert unsigned integer operand 1 of mode @var{m} to fixed-point mode | |
6045 | @var{n} and store in operand 0 (which has mode @var{n}). | |
6046 | When overflows or underflows happen, the instruction saturates the | |
6047 | results to the maximum or the minimum. | |
6048 | ||
d2eeb2d1 RS |
6049 | @cindex @code{extv@var{m}} instruction pattern |
6050 | @item @samp{extv@var{m}} | |
6051 | Extract a bit-field from register operand 1, sign-extend it, and store | |
6052 | it in operand 0. Operand 2 specifies the width of the field in bits | |
6053 | and operand 3 the starting bit, which counts from the most significant | |
6054 | bit if @samp{BITS_BIG_ENDIAN} is true and from the least significant bit | |
6055 | otherwise. | |
6056 | ||
6057 | Operands 0 and 1 both have mode @var{m}. Operands 2 and 3 have a | |
6058 | target-specific mode. | |
6059 | ||
6060 | @cindex @code{extvmisalign@var{m}} instruction pattern | |
6061 | @item @samp{extvmisalign@var{m}} | |
6062 | Extract a bit-field from memory operand 1, sign extend it, and store | |
6063 | it in operand 0. Operand 2 specifies the width in bits and operand 3 | |
6064 | the starting bit. The starting bit is always somewhere in the first byte of | |
6065 | operand 1; it counts from the most significant bit if @samp{BITS_BIG_ENDIAN} | |
6066 | is true and from the least significant bit otherwise. | |
6067 | ||
6068 | Operand 0 has mode @var{m} while operand 1 has @code{BLK} mode. | |
6069 | Operands 2 and 3 have a target-specific mode. | |
6070 | ||
6071 | The instruction must not read beyond the last byte of the bit-field. | |
6072 | ||
6073 | @cindex @code{extzv@var{m}} instruction pattern | |
6074 | @item @samp{extzv@var{m}} | |
6075 | Like @samp{extv@var{m}} except that the bit-field value is zero-extended. | |
6076 | ||
6077 | @cindex @code{extzvmisalign@var{m}} instruction pattern | |
6078 | @item @samp{extzvmisalign@var{m}} | |
6079 | Like @samp{extvmisalign@var{m}} except that the bit-field value is | |
6080 | zero-extended. | |
6081 | ||
6082 | @cindex @code{insv@var{m}} instruction pattern | |
6083 | @item @samp{insv@var{m}} | |
6084 | Insert operand 3 into a bit-field of register operand 0. Operand 1 | |
6085 | specifies the width of the field in bits and operand 2 the starting bit, | |
6086 | which counts from the most significant bit if @samp{BITS_BIG_ENDIAN} | |
6087 | is true and from the least significant bit otherwise. | |
6088 | ||
6089 | Operands 0 and 3 both have mode @var{m}. Operands 1 and 2 have a | |
6090 | target-specific mode. | |
6091 | ||
6092 | @cindex @code{insvmisalign@var{m}} instruction pattern | |
6093 | @item @samp{insvmisalign@var{m}} | |
6094 | Insert operand 3 into a bit-field of memory operand 0. Operand 1 | |
6095 | specifies the width of the field in bits and operand 2 the starting bit. | |
6096 | The starting bit is always somewhere in the first byte of operand 0; | |
6097 | it counts from the most significant bit if @samp{BITS_BIG_ENDIAN} | |
6098 | is true and from the least significant bit otherwise. | |
6099 | ||
6100 | Operand 3 has mode @var{m} while operand 0 has @code{BLK} mode. | |
6101 | Operands 1 and 2 have a target-specific mode. | |
6102 | ||
6103 | The instruction must not read or write beyond the last byte of the bit-field. | |
6104 | ||
03dda8e3 RK |
6105 | @cindex @code{extv} instruction pattern |
6106 | @item @samp{extv} | |
c771326b | 6107 | Extract a bit-field from operand 1 (a register or memory operand), where |
03dda8e3 RK |
6108 | operand 2 specifies the width in bits and operand 3 the starting bit, |
6109 | and store it in operand 0. Operand 0 must have mode @code{word_mode}. | |
6110 | Operand 1 may have mode @code{byte_mode} or @code{word_mode}; often | |
6111 | @code{word_mode} is allowed only for registers. Operands 2 and 3 must | |
6112 | be valid for @code{word_mode}. | |
6113 | ||
6114 | The RTL generation pass generates this instruction only with constants | |
3ab997e8 | 6115 | for operands 2 and 3 and the constant is never zero for operand 2. |
03dda8e3 RK |
6116 | |
6117 | The bit-field value is sign-extended to a full word integer | |
6118 | before it is stored in operand 0. | |
6119 | ||
d2eeb2d1 RS |
6120 | This pattern is deprecated; please use @samp{extv@var{m}} and |
6121 | @code{extvmisalign@var{m}} instead. | |
6122 | ||
03dda8e3 RK |
6123 | @cindex @code{extzv} instruction pattern |
6124 | @item @samp{extzv} | |
6125 | Like @samp{extv} except that the bit-field value is zero-extended. | |
6126 | ||
d2eeb2d1 RS |
6127 | This pattern is deprecated; please use @samp{extzv@var{m}} and |
6128 | @code{extzvmisalign@var{m}} instead. | |
6129 | ||
03dda8e3 RK |
6130 | @cindex @code{insv} instruction pattern |
6131 | @item @samp{insv} | |
c771326b JM |
6132 | Store operand 3 (which must be valid for @code{word_mode}) into a |
6133 | bit-field in operand 0, where operand 1 specifies the width in bits and | |
03dda8e3 RK |
6134 | operand 2 the starting bit. Operand 0 may have mode @code{byte_mode} or |
6135 | @code{word_mode}; often @code{word_mode} is allowed only for registers. | |
6136 | Operands 1 and 2 must be valid for @code{word_mode}. | |
6137 | ||
6138 | The RTL generation pass generates this instruction only with constants | |
3ab997e8 | 6139 | for operands 1 and 2 and the constant is never zero for operand 1. |
03dda8e3 | 6140 | |
d2eeb2d1 RS |
6141 | This pattern is deprecated; please use @samp{insv@var{m}} and |
6142 | @code{insvmisalign@var{m}} instead. | |
6143 | ||
03dda8e3 RK |
6144 | @cindex @code{mov@var{mode}cc} instruction pattern |
6145 | @item @samp{mov@var{mode}cc} | |
6146 | Conditionally move operand 2 or operand 3 into operand 0 according to the | |
6147 | comparison in operand 1. If the comparison is true, operand 2 is moved | |
6148 | into operand 0, otherwise operand 3 is moved. | |
6149 | ||
6150 | The mode of the operands being compared need not be the same as the operands | |
6151 | being moved. Some machines, sparc64 for example, have instructions that | |
6152 | conditionally move an integer value based on the floating point condition | |
6153 | codes and vice versa. | |
6154 | ||
6155 | If the machine does not have conditional move instructions, do not | |
6156 | define these patterns. | |
6157 | ||
068f5dea | 6158 | @cindex @code{add@var{mode}cc} instruction pattern |
4b5cc2b3 | 6159 | @item @samp{add@var{mode}cc} |
068f5dea JH |
6160 | Similar to @samp{mov@var{mode}cc} but for conditional addition. Conditionally |
6161 | move operand 2 or (operands 2 + operand 3) into operand 0 according to the | |
5285c21c | 6162 | comparison in operand 1. If the comparison is false, operand 2 is moved into |
4b5cc2b3 | 6163 | operand 0, otherwise (operand 2 + operand 3) is moved. |
068f5dea | 6164 | |
ce68b5cf KT |
6165 | @cindex @code{neg@var{mode}cc} instruction pattern |
6166 | @item @samp{neg@var{mode}cc} | |
6167 | Similar to @samp{mov@var{mode}cc} but for conditional negation. Conditionally | |
6168 | move the negation of operand 2 or the unchanged operand 3 into operand 0 | |
6169 | according to the comparison in operand 1. If the comparison is true, the negation | |
6170 | of operand 2 is moved into operand 0, otherwise operand 3 is moved. | |
6171 | ||
6172 | @cindex @code{not@var{mode}cc} instruction pattern | |
6173 | @item @samp{not@var{mode}cc} | |
6174 | Similar to @samp{neg@var{mode}cc} but for conditional complement. | |
6175 | Conditionally move the bitwise complement of operand 2 or the unchanged | |
6176 | operand 3 into operand 0 according to the comparison in operand 1. | |
6177 | If the comparison is true, the complement of operand 2 is moved into | |
6178 | operand 0, otherwise operand 3 is moved. | |
6179 | ||
f90b7a5a PB |
6180 | @cindex @code{cstore@var{mode}4} instruction pattern |
6181 | @item @samp{cstore@var{mode}4} | |
6182 | Store zero or nonzero in operand 0 according to whether a comparison | |
6183 | is true. Operand 1 is a comparison operator. Operand 2 and operand 3 | |
6184 | are the first and second operand of the comparison, respectively. | |
6185 | You specify the mode that operand 0 must have when you write the | |
6186 | @code{match_operand} expression. The compiler automatically sees which | |
6187 | mode you have used and supplies an operand of that mode. | |
03dda8e3 RK |
6188 | |
6189 | The value stored for a true condition must have 1 as its low bit, or | |
6190 | else must be negative. Otherwise the instruction is not suitable and | |
6191 | you should omit it from the machine description. You describe to the | |
6192 | compiler exactly which value is stored by defining the macro | |
6193 | @code{STORE_FLAG_VALUE} (@pxref{Misc}). If a description cannot be | |
ac5eda13 PB |
6194 | found that can be used for all the possible comparison operators, you |
6195 | should pick one and use a @code{define_expand} to map all results | |
6196 | onto the one you chose. | |
6197 | ||
6198 | These operations may @code{FAIL}, but should do so only in relatively | |
6199 | uncommon cases; if they would @code{FAIL} for common cases involving | |
6200 | integer comparisons, it is best to restrict the predicates to not | |
6201 | allow these operands. Likewise if a given comparison operator will | |
6202 | always fail, independent of the operands (for floating-point modes, the | |
6203 | @code{ordered_comparison_operator} predicate is often useful in this case). | |
6204 | ||
6205 | If this pattern is omitted, the compiler will generate a conditional | |
6206 | branch---for example, it may copy a constant one to the target and branching | |
6207 | around an assignment of zero to the target---or a libcall. If the predicate | |
6208 | for operand 1 only rejects some operators, it will also try reordering the | |
6209 | operands and/or inverting the result value (e.g.@: by an exclusive OR). | |
6210 | These possibilities could be cheaper or equivalent to the instructions | |
6211 | used for the @samp{cstore@var{mode}4} pattern followed by those required | |
6212 | to convert a positive result from @code{STORE_FLAG_VALUE} to 1; in this | |
6213 | case, you can and should make operand 1's predicate reject some operators | |
6214 | in the @samp{cstore@var{mode}4} pattern, or remove the pattern altogether | |
6215 | from the machine description. | |
03dda8e3 | 6216 | |
66c87bae KH |
6217 | @cindex @code{cbranch@var{mode}4} instruction pattern |
6218 | @item @samp{cbranch@var{mode}4} | |
6219 | Conditional branch instruction combined with a compare instruction. | |
6220 | Operand 0 is a comparison operator. Operand 1 and operand 2 are the | |
6221 | first and second operands of the comparison, respectively. Operand 3 | |
481efdd9 | 6222 | is the @code{code_label} to jump to. |
66c87bae | 6223 | |
d26eedb6 HPN |
6224 | @cindex @code{jump} instruction pattern |
6225 | @item @samp{jump} | |
6226 | A jump inside a function; an unconditional branch. Operand 0 is the | |
481efdd9 EB |
6227 | @code{code_label} to jump to. This pattern name is mandatory on all |
6228 | machines. | |
d26eedb6 | 6229 | |
03dda8e3 RK |
6230 | @cindex @code{call} instruction pattern |
6231 | @item @samp{call} | |
6232 | Subroutine call instruction returning no value. Operand 0 is the | |
6233 | function to call; operand 1 is the number of bytes of arguments pushed | |
f5963e61 JL |
6234 | as a @code{const_int}; operand 2 is the number of registers used as |
6235 | operands. | |
03dda8e3 RK |
6236 | |
6237 | On most machines, operand 2 is not actually stored into the RTL | |
6238 | pattern. It is supplied for the sake of some RISC machines which need | |
6239 | to put this information into the assembler code; they can put it in | |
6240 | the RTL instead of operand 1. | |
6241 | ||
6242 | Operand 0 should be a @code{mem} RTX whose address is the address of the | |
6243 | function. Note, however, that this address can be a @code{symbol_ref} | |
6244 | expression even if it would not be a legitimate memory address on the | |
6245 | target machine. If it is also not a valid argument for a call | |
6246 | instruction, the pattern for this operation should be a | |
6247 | @code{define_expand} (@pxref{Expander Definitions}) that places the | |
6248 | address into a register and uses that register in the call instruction. | |
6249 | ||
6250 | @cindex @code{call_value} instruction pattern | |
6251 | @item @samp{call_value} | |
6252 | Subroutine call instruction returning a value. Operand 0 is the hard | |
6253 | register in which the value is returned. There are three more | |
6254 | operands, the same as the three operands of the @samp{call} | |
6255 | instruction (but with numbers increased by one). | |
6256 | ||
6257 | Subroutines that return @code{BLKmode} objects use the @samp{call} | |
6258 | insn. | |
6259 | ||
6260 | @cindex @code{call_pop} instruction pattern | |
6261 | @cindex @code{call_value_pop} instruction pattern | |
6262 | @item @samp{call_pop}, @samp{call_value_pop} | |
6263 | Similar to @samp{call} and @samp{call_value}, except used if defined and | |
df2a54e9 | 6264 | if @code{RETURN_POPS_ARGS} is nonzero. They should emit a @code{parallel} |
03dda8e3 RK |
6265 | that contains both the function call and a @code{set} to indicate the |
6266 | adjustment made to the frame pointer. | |
6267 | ||
df2a54e9 | 6268 | For machines where @code{RETURN_POPS_ARGS} can be nonzero, the use of these |
03dda8e3 RK |
6269 | patterns increases the number of functions for which the frame pointer |
6270 | can be eliminated, if desired. | |
6271 | ||
6272 | @cindex @code{untyped_call} instruction pattern | |
6273 | @item @samp{untyped_call} | |
6274 | Subroutine call instruction returning a value of any type. Operand 0 is | |
6275 | the function to call; operand 1 is a memory location where the result of | |
6276 | calling the function is to be stored; operand 2 is a @code{parallel} | |
6277 | expression where each element is a @code{set} expression that indicates | |
6278 | the saving of a function return value into the result block. | |
6279 | ||
6280 | This instruction pattern should be defined to support | |
6281 | @code{__builtin_apply} on machines where special instructions are needed | |
6282 | to call a subroutine with arbitrary arguments or to save the value | |
6283 | returned. This instruction pattern is required on machines that have | |
e979f9e8 JM |
6284 | multiple registers that can hold a return value |
6285 | (i.e.@: @code{FUNCTION_VALUE_REGNO_P} is true for more than one register). | |
03dda8e3 RK |
6286 | |
6287 | @cindex @code{return} instruction pattern | |
6288 | @item @samp{return} | |
6289 | Subroutine return instruction. This instruction pattern name should be | |
6290 | defined only if a single instruction can do all the work of returning | |
6291 | from a function. | |
6292 | ||
6293 | Like the @samp{mov@var{m}} patterns, this pattern is also used after the | |
6294 | RTL generation phase. In this case it is to support machines where | |
6295 | multiple instructions are usually needed to return from a function, but | |
6296 | some class of functions only requires one instruction to implement a | |
6297 | return. Normally, the applicable functions are those which do not need | |
6298 | to save any registers or allocate stack space. | |
6299 | ||
26898771 BS |
6300 | It is valid for this pattern to expand to an instruction using |
6301 | @code{simple_return} if no epilogue is required. | |
6302 | ||
6303 | @cindex @code{simple_return} instruction pattern | |
6304 | @item @samp{simple_return} | |
6305 | Subroutine return instruction. This instruction pattern name should be | |
6306 | defined only if a single instruction can do all the work of returning | |
6307 | from a function on a path where no epilogue is required. This pattern | |
6308 | is very similar to the @code{return} instruction pattern, but it is emitted | |
6309 | only by the shrink-wrapping optimization on paths where the function | |
6310 | prologue has not been executed, and a function return should occur without | |
6311 | any of the effects of the epilogue. Additional uses may be introduced on | |
6312 | paths where both the prologue and the epilogue have executed. | |
6313 | ||
03dda8e3 RK |
6314 | @findex reload_completed |
6315 | @findex leaf_function_p | |
6316 | For such machines, the condition specified in this pattern should only | |
df2a54e9 | 6317 | be true when @code{reload_completed} is nonzero and the function's |
03dda8e3 RK |
6318 | epilogue would only be a single instruction. For machines with register |
6319 | windows, the routine @code{leaf_function_p} may be used to determine if | |
6320 | a register window push is required. | |
6321 | ||
6322 | Machines that have conditional return instructions should define patterns | |
6323 | such as | |
6324 | ||
6325 | @smallexample | |
6326 | (define_insn "" | |
6327 | [(set (pc) | |
6328 | (if_then_else (match_operator | |
6329 | 0 "comparison_operator" | |
6330 | [(cc0) (const_int 0)]) | |
6331 | (return) | |
6332 | (pc)))] | |
6333 | "@var{condition}" | |
6334 | "@dots{}") | |
6335 | @end smallexample | |
6336 | ||
6337 | where @var{condition} would normally be the same condition specified on the | |
6338 | named @samp{return} pattern. | |
6339 | ||
6340 | @cindex @code{untyped_return} instruction pattern | |
6341 | @item @samp{untyped_return} | |
6342 | Untyped subroutine return instruction. This instruction pattern should | |
6343 | be defined to support @code{__builtin_return} on machines where special | |
6344 | instructions are needed to return a value of any type. | |
6345 | ||
6346 | Operand 0 is a memory location where the result of calling a function | |
6347 | with @code{__builtin_apply} is stored; operand 1 is a @code{parallel} | |
6348 | expression where each element is a @code{set} expression that indicates | |
6349 | the restoring of a function return value from the result block. | |
6350 | ||
6351 | @cindex @code{nop} instruction pattern | |
6352 | @item @samp{nop} | |
6353 | No-op instruction. This instruction pattern name should always be defined | |
6354 | to output a no-op in assembler code. @code{(const_int 0)} will do as an | |
6355 | RTL pattern. | |
6356 | ||
6357 | @cindex @code{indirect_jump} instruction pattern | |
6358 | @item @samp{indirect_jump} | |
6359 | An instruction to jump to an address which is operand zero. | |
6360 | This pattern name is mandatory on all machines. | |
6361 | ||
6362 | @cindex @code{casesi} instruction pattern | |
6363 | @item @samp{casesi} | |
6364 | Instruction to jump through a dispatch table, including bounds checking. | |
6365 | This instruction takes five operands: | |
6366 | ||
6367 | @enumerate | |
6368 | @item | |
6369 | The index to dispatch on, which has mode @code{SImode}. | |
6370 | ||
6371 | @item | |
6372 | The lower bound for indices in the table, an integer constant. | |
6373 | ||
6374 | @item | |
6375 | The total range of indices in the table---the largest index | |
6376 | minus the smallest one (both inclusive). | |
6377 | ||
6378 | @item | |
6379 | A label that precedes the table itself. | |
6380 | ||
6381 | @item | |
6382 | A label to jump to if the index has a value outside the bounds. | |
03dda8e3 RK |
6383 | @end enumerate |
6384 | ||
e4ae5e77 | 6385 | The table is an @code{addr_vec} or @code{addr_diff_vec} inside of a |
da5c6bde | 6386 | @code{jump_table_data}. The number of elements in the table is one plus the |
03dda8e3 RK |
6387 | difference between the upper bound and the lower bound. |
6388 | ||
6389 | @cindex @code{tablejump} instruction pattern | |
6390 | @item @samp{tablejump} | |
6391 | Instruction to jump to a variable address. This is a low-level | |
6392 | capability which can be used to implement a dispatch table when there | |
6393 | is no @samp{casesi} pattern. | |
6394 | ||
6395 | This pattern requires two operands: the address or offset, and a label | |
6396 | which should immediately precede the jump table. If the macro | |
f1f5f142 JL |
6397 | @code{CASE_VECTOR_PC_RELATIVE} evaluates to a nonzero value then the first |
6398 | operand is an offset which counts from the address of the table; otherwise, | |
6399 | it is an absolute address to jump to. In either case, the first operand has | |
03dda8e3 RK |
6400 | mode @code{Pmode}. |
6401 | ||
6402 | The @samp{tablejump} insn is always the last insn before the jump | |
6403 | table it uses. Its assembler code normally has no need to use the | |
6404 | second operand, but you should incorporate it in the RTL pattern so | |
6405 | that the jump optimizer will not delete the table as unreachable code. | |
6406 | ||
6e4fcc95 MH |
6407 | |
6408 | @cindex @code{decrement_and_branch_until_zero} instruction pattern | |
6409 | @item @samp{decrement_and_branch_until_zero} | |
6410 | Conditional branch instruction that decrements a register and | |
df2a54e9 | 6411 | jumps if the register is nonzero. Operand 0 is the register to |
6e4fcc95 | 6412 | decrement and test; operand 1 is the label to jump to if the |
df2a54e9 | 6413 | register is nonzero. @xref{Looping Patterns}. |
6e4fcc95 MH |
6414 | |
6415 | This optional instruction pattern is only used by the combiner, | |
6416 | typically for loops reversed by the loop optimizer when strength | |
6417 | reduction is enabled. | |
6418 | ||
6419 | @cindex @code{doloop_end} instruction pattern | |
6420 | @item @samp{doloop_end} | |
1d0216c8 RS |
6421 | Conditional branch instruction that decrements a register and |
6422 | jumps if the register is nonzero. Operand 0 is the register to | |
6423 | decrement and test; operand 1 is the label to jump to if the | |
6424 | register is nonzero. | |
5c25e11d | 6425 | @xref{Looping Patterns}. |
6e4fcc95 MH |
6426 | |
6427 | This optional instruction pattern should be defined for machines with | |
6428 | low-overhead looping instructions as the loop optimizer will try to | |
1d0216c8 RS |
6429 | modify suitable loops to utilize it. The target hook |
6430 | @code{TARGET_CAN_USE_DOLOOP_P} controls the conditions under which | |
6431 | low-overhead loops can be used. | |
6e4fcc95 MH |
6432 | |
6433 | @cindex @code{doloop_begin} instruction pattern | |
6434 | @item @samp{doloop_begin} | |
6435 | Companion instruction to @code{doloop_end} required for machines that | |
1d0216c8 RS |
6436 | need to perform some initialization, such as loading a special counter |
6437 | register. Operand 1 is the associated @code{doloop_end} pattern and | |
6438 | operand 0 is the register that it decrements. | |
6e4fcc95 | 6439 | |
1d0216c8 RS |
6440 | If initialization insns do not always need to be emitted, use a |
6441 | @code{define_expand} (@pxref{Expander Definitions}) and make it fail. | |
6e4fcc95 | 6442 | |
03dda8e3 RK |
6443 | @cindex @code{canonicalize_funcptr_for_compare} instruction pattern |
6444 | @item @samp{canonicalize_funcptr_for_compare} | |
6445 | Canonicalize the function pointer in operand 1 and store the result | |
6446 | into operand 0. | |
6447 | ||
6448 | Operand 0 is always a @code{reg} and has mode @code{Pmode}; operand 1 | |
6449 | may be a @code{reg}, @code{mem}, @code{symbol_ref}, @code{const_int}, etc | |
6450 | and also has mode @code{Pmode}. | |
6451 | ||
6452 | Canonicalization of a function pointer usually involves computing | |
6453 | the address of the function which would be called if the function | |
6454 | pointer were used in an indirect call. | |
6455 | ||
6456 | Only define this pattern if function pointers on the target machine | |
6457 | can have different values but still call the same function when | |
6458 | used in an indirect call. | |
6459 | ||
6460 | @cindex @code{save_stack_block} instruction pattern | |
6461 | @cindex @code{save_stack_function} instruction pattern | |
6462 | @cindex @code{save_stack_nonlocal} instruction pattern | |
6463 | @cindex @code{restore_stack_block} instruction pattern | |
6464 | @cindex @code{restore_stack_function} instruction pattern | |
6465 | @cindex @code{restore_stack_nonlocal} instruction pattern | |
6466 | @item @samp{save_stack_block} | |
6467 | @itemx @samp{save_stack_function} | |
6468 | @itemx @samp{save_stack_nonlocal} | |
6469 | @itemx @samp{restore_stack_block} | |
6470 | @itemx @samp{restore_stack_function} | |
6471 | @itemx @samp{restore_stack_nonlocal} | |
6472 | Most machines save and restore the stack pointer by copying it to or | |
6473 | from an object of mode @code{Pmode}. Do not define these patterns on | |
6474 | such machines. | |
6475 | ||
6476 | Some machines require special handling for stack pointer saves and | |
6477 | restores. On those machines, define the patterns corresponding to the | |
6478 | non-standard cases by using a @code{define_expand} (@pxref{Expander | |
6479 | Definitions}) that produces the required insns. The three types of | |
6480 | saves and restores are: | |
6481 | ||
6482 | @enumerate | |
6483 | @item | |
6484 | @samp{save_stack_block} saves the stack pointer at the start of a block | |
6485 | that allocates a variable-sized object, and @samp{restore_stack_block} | |
6486 | restores the stack pointer when the block is exited. | |
6487 | ||
6488 | @item | |
6489 | @samp{save_stack_function} and @samp{restore_stack_function} do a | |
6490 | similar job for the outermost block of a function and are used when the | |
6491 | function allocates variable-sized objects or calls @code{alloca}. Only | |
6492 | the epilogue uses the restored stack pointer, allowing a simpler save or | |
6493 | restore sequence on some machines. | |
6494 | ||
6495 | @item | |
6496 | @samp{save_stack_nonlocal} is used in functions that contain labels | |
6497 | branched to by nested functions. It saves the stack pointer in such a | |
6498 | way that the inner function can use @samp{restore_stack_nonlocal} to | |
6499 | restore the stack pointer. The compiler generates code to restore the | |
6500 | frame and argument pointer registers, but some machines require saving | |
6501 | and restoring additional data such as register window information or | |
6502 | stack backchains. Place insns in these patterns to save and restore any | |
6503 | such required data. | |
6504 | @end enumerate | |
6505 | ||
6506 | When saving the stack pointer, operand 0 is the save area and operand 1 | |
73c8090f DE |
6507 | is the stack pointer. The mode used to allocate the save area defaults |
6508 | to @code{Pmode} but you can override that choice by defining the | |
7e390c9d | 6509 | @code{STACK_SAVEAREA_MODE} macro (@pxref{Storage Layout}). You must |
73c8090f DE |
6510 | specify an integral mode, or @code{VOIDmode} if no save area is needed |
6511 | for a particular type of save (either because no save is needed or | |
6512 | because a machine-specific save area can be used). Operand 0 is the | |
6513 | stack pointer and operand 1 is the save area for restore operations. If | |
6514 | @samp{save_stack_block} is defined, operand 0 must not be | |
6515 | @code{VOIDmode} since these saves can be arbitrarily nested. | |
03dda8e3 RK |
6516 | |
6517 | A save area is a @code{mem} that is at a constant offset from | |
6518 | @code{virtual_stack_vars_rtx} when the stack pointer is saved for use by | |
6519 | nonlocal gotos and a @code{reg} in the other two cases. | |
6520 | ||
6521 | @cindex @code{allocate_stack} instruction pattern | |
6522 | @item @samp{allocate_stack} | |
72938a4c | 6523 | Subtract (or add if @code{STACK_GROWS_DOWNWARD} is undefined) operand 1 from |
03dda8e3 RK |
6524 | the stack pointer to create space for dynamically allocated data. |
6525 | ||
72938a4c MM |
6526 | Store the resultant pointer to this space into operand 0. If you |
6527 | are allocating space from the main stack, do this by emitting a | |
6528 | move insn to copy @code{virtual_stack_dynamic_rtx} to operand 0. | |
6529 | If you are allocating the space elsewhere, generate code to copy the | |
6530 | location of the space to operand 0. In the latter case, you must | |
956d6950 | 6531 | ensure this space gets freed when the corresponding space on the main |
72938a4c MM |
6532 | stack is free. |
6533 | ||
03dda8e3 RK |
6534 | Do not define this pattern if all that must be done is the subtraction. |
6535 | Some machines require other operations such as stack probes or | |
6536 | maintaining the back chain. Define this pattern to emit those | |
6537 | operations in addition to updating the stack pointer. | |
6538 | ||
861bb6c1 JL |
6539 | @cindex @code{check_stack} instruction pattern |
6540 | @item @samp{check_stack} | |
507d0069 EB |
6541 | If stack checking (@pxref{Stack Checking}) cannot be done on your system by |
6542 | probing the stack, define this pattern to perform the needed check and signal | |
6543 | an error if the stack has overflowed. The single operand is the address in | |
6544 | the stack farthest from the current stack pointer that you need to validate. | |
6545 | Normally, on platforms where this pattern is needed, you would obtain the | |
6546 | stack limit from a global or thread-specific variable or register. | |
d809253a | 6547 | |
7b84aac0 EB |
6548 | @cindex @code{probe_stack_address} instruction pattern |
6549 | @item @samp{probe_stack_address} | |
6550 | If stack checking (@pxref{Stack Checking}) can be done on your system by | |
6551 | probing the stack but without the need to actually access it, define this | |
6552 | pattern and signal an error if the stack has overflowed. The single operand | |
6553 | is the memory address in the stack that needs to be probed. | |
6554 | ||
d809253a EB |
6555 | @cindex @code{probe_stack} instruction pattern |
6556 | @item @samp{probe_stack} | |
507d0069 EB |
6557 | If stack checking (@pxref{Stack Checking}) can be done on your system by |
6558 | probing the stack but doing it with a ``store zero'' instruction is not valid | |
6559 | or optimal, define this pattern to do the probing differently and signal an | |
6560 | error if the stack has overflowed. The single operand is the memory reference | |
6561 | in the stack that needs to be probed. | |
861bb6c1 | 6562 | |
03dda8e3 RK |
6563 | @cindex @code{nonlocal_goto} instruction pattern |
6564 | @item @samp{nonlocal_goto} | |
6565 | Emit code to generate a non-local goto, e.g., a jump from one function | |
6566 | to a label in an outer function. This pattern has four arguments, | |
6567 | each representing a value to be used in the jump. The first | |
45bb86fd | 6568 | argument is to be loaded into the frame pointer, the second is |
03dda8e3 RK |
6569 | the address to branch to (code to dispatch to the actual label), |
6570 | the third is the address of a location where the stack is saved, | |
6571 | and the last is the address of the label, to be placed in the | |
6572 | location for the incoming static chain. | |
6573 | ||
f0523f02 | 6574 | On most machines you need not define this pattern, since GCC will |
03dda8e3 RK |
6575 | already generate the correct code, which is to load the frame pointer |
6576 | and static chain, restore the stack (using the | |
6577 | @samp{restore_stack_nonlocal} pattern, if defined), and jump indirectly | |
6578 | to the dispatcher. You need only define this pattern if this code will | |
6579 | not work on your machine. | |
6580 | ||
6581 | @cindex @code{nonlocal_goto_receiver} instruction pattern | |
6582 | @item @samp{nonlocal_goto_receiver} | |
6583 | This pattern, if defined, contains code needed at the target of a | |
161d7b59 | 6584 | nonlocal goto after the code already generated by GCC@. You will not |
03dda8e3 RK |
6585 | normally need to define this pattern. A typical reason why you might |
6586 | need this pattern is if some value, such as a pointer to a global table, | |
c30ddbc9 | 6587 | must be restored when the frame pointer is restored. Note that a nonlocal |
89bcce1b | 6588 | goto only occurs within a unit-of-translation, so a global table pointer |
c30ddbc9 RH |
6589 | that is shared by all functions of a given module need not be restored. |
6590 | There are no arguments. | |
861bb6c1 JL |
6591 | |
6592 | @cindex @code{exception_receiver} instruction pattern | |
6593 | @item @samp{exception_receiver} | |
6594 | This pattern, if defined, contains code needed at the site of an | |
6595 | exception handler that isn't needed at the site of a nonlocal goto. You | |
6596 | will not normally need to define this pattern. A typical reason why you | |
6597 | might need this pattern is if some value, such as a pointer to a global | |
6598 | table, must be restored after control flow is branched to the handler of | |
6599 | an exception. There are no arguments. | |
c85f7c16 | 6600 | |
c30ddbc9 RH |
6601 | @cindex @code{builtin_setjmp_setup} instruction pattern |
6602 | @item @samp{builtin_setjmp_setup} | |
6603 | This pattern, if defined, contains additional code needed to initialize | |
6604 | the @code{jmp_buf}. You will not normally need to define this pattern. | |
6605 | A typical reason why you might need this pattern is if some value, such | |
6606 | as a pointer to a global table, must be restored. Though it is | |
6607 | preferred that the pointer value be recalculated if possible (given the | |
6608 | address of a label for instance). The single argument is a pointer to | |
6609 | the @code{jmp_buf}. Note that the buffer is five words long and that | |
6610 | the first three are normally used by the generic mechanism. | |
6611 | ||
c85f7c16 JL |
6612 | @cindex @code{builtin_setjmp_receiver} instruction pattern |
6613 | @item @samp{builtin_setjmp_receiver} | |
e4ae5e77 | 6614 | This pattern, if defined, contains code needed at the site of a |
c771326b | 6615 | built-in setjmp that isn't needed at the site of a nonlocal goto. You |
c85f7c16 JL |
6616 | will not normally need to define this pattern. A typical reason why you |
6617 | might need this pattern is if some value, such as a pointer to a global | |
c30ddbc9 | 6618 | table, must be restored. It takes one argument, which is the label |
073a8998 | 6619 | to which builtin_longjmp transferred control; this pattern may be emitted |
c30ddbc9 RH |
6620 | at a small offset from that label. |
6621 | ||
6622 | @cindex @code{builtin_longjmp} instruction pattern | |
6623 | @item @samp{builtin_longjmp} | |
6624 | This pattern, if defined, performs the entire action of the longjmp. | |
6625 | You will not normally need to define this pattern unless you also define | |
6626 | @code{builtin_setjmp_setup}. The single argument is a pointer to the | |
6627 | @code{jmp_buf}. | |
f69864aa | 6628 | |
52a11cbf RH |
6629 | @cindex @code{eh_return} instruction pattern |
6630 | @item @samp{eh_return} | |
f69864aa | 6631 | This pattern, if defined, affects the way @code{__builtin_eh_return}, |
52a11cbf RH |
6632 | and thence the call frame exception handling library routines, are |
6633 | built. It is intended to handle non-trivial actions needed along | |
6634 | the abnormal return path. | |
6635 | ||
34dc173c | 6636 | The address of the exception handler to which the function should return |
daf2f129 | 6637 | is passed as operand to this pattern. It will normally need to copied by |
34dc173c UW |
6638 | the pattern to some special register or memory location. |
6639 | If the pattern needs to determine the location of the target call | |
6640 | frame in order to do so, it may use @code{EH_RETURN_STACKADJ_RTX}, | |
6641 | if defined; it will have already been assigned. | |
6642 | ||
6643 | If this pattern is not defined, the default action will be to simply | |
6644 | copy the return address to @code{EH_RETURN_HANDLER_RTX}. Either | |
6645 | that macro or this pattern needs to be defined if call frame exception | |
6646 | handling is to be used. | |
0b433de6 JL |
6647 | |
6648 | @cindex @code{prologue} instruction pattern | |
17b53c33 | 6649 | @anchor{prologue instruction pattern} |
0b433de6 JL |
6650 | @item @samp{prologue} |
6651 | This pattern, if defined, emits RTL for entry to a function. The function | |
b192711e | 6652 | entry is responsible for setting up the stack frame, initializing the frame |
0b433de6 JL |
6653 | pointer register, saving callee saved registers, etc. |
6654 | ||
6655 | Using a prologue pattern is generally preferred over defining | |
17b53c33 | 6656 | @code{TARGET_ASM_FUNCTION_PROLOGUE} to emit assembly code for the prologue. |
0b433de6 JL |
6657 | |
6658 | The @code{prologue} pattern is particularly useful for targets which perform | |
6659 | instruction scheduling. | |
6660 | ||
12c5ffe5 EB |
6661 | @cindex @code{window_save} instruction pattern |
6662 | @anchor{window_save instruction pattern} | |
6663 | @item @samp{window_save} | |
6664 | This pattern, if defined, emits RTL for a register window save. It should | |
6665 | be defined if the target machine has register windows but the window events | |
6666 | are decoupled from calls to subroutines. The canonical example is the SPARC | |
6667 | architecture. | |
6668 | ||
0b433de6 | 6669 | @cindex @code{epilogue} instruction pattern |
17b53c33 | 6670 | @anchor{epilogue instruction pattern} |
0b433de6 | 6671 | @item @samp{epilogue} |
396ad517 | 6672 | This pattern emits RTL for exit from a function. The function |
b192711e | 6673 | exit is responsible for deallocating the stack frame, restoring callee saved |
0b433de6 JL |
6674 | registers and emitting the return instruction. |
6675 | ||
6676 | Using an epilogue pattern is generally preferred over defining | |
17b53c33 | 6677 | @code{TARGET_ASM_FUNCTION_EPILOGUE} to emit assembly code for the epilogue. |
0b433de6 JL |
6678 | |
6679 | The @code{epilogue} pattern is particularly useful for targets which perform | |
6680 | instruction scheduling or which have delay slots for their return instruction. | |
6681 | ||
6682 | @cindex @code{sibcall_epilogue} instruction pattern | |
6683 | @item @samp{sibcall_epilogue} | |
6684 | This pattern, if defined, emits RTL for exit from a function without the final | |
6685 | branch back to the calling function. This pattern will be emitted before any | |
6686 | sibling call (aka tail call) sites. | |
6687 | ||
6688 | The @code{sibcall_epilogue} pattern must not clobber any arguments used for | |
6689 | parameter passing or any stack slots for arguments passed to the current | |
ebb48a4d | 6690 | function. |
a157febd GK |
6691 | |
6692 | @cindex @code{trap} instruction pattern | |
6693 | @item @samp{trap} | |
6694 | This pattern, if defined, signals an error, typically by causing some | |
4b1ea1f3 | 6695 | kind of signal to be raised. |
a157febd | 6696 | |
f90b7a5a PB |
6697 | @cindex @code{ctrap@var{MM}4} instruction pattern |
6698 | @item @samp{ctrap@var{MM}4} | |
a157febd | 6699 | Conditional trap instruction. Operand 0 is a piece of RTL which |
f90b7a5a PB |
6700 | performs a comparison, and operands 1 and 2 are the arms of the |
6701 | comparison. Operand 3 is the trap code, an integer. | |
a157febd | 6702 | |
f90b7a5a | 6703 | A typical @code{ctrap} pattern looks like |
a157febd GK |
6704 | |
6705 | @smallexample | |
f90b7a5a | 6706 | (define_insn "ctrapsi4" |
ebb48a4d | 6707 | [(trap_if (match_operator 0 "trap_operator" |
f90b7a5a | 6708 | [(match_operand 1 "register_operand") |
73b8bfe1 | 6709 | (match_operand 2 "immediate_operand")]) |
f90b7a5a | 6710 | (match_operand 3 "const_int_operand" "i"))] |
a157febd GK |
6711 | "" |
6712 | "@dots{}") | |
6713 | @end smallexample | |
6714 | ||
e83d297b JJ |
6715 | @cindex @code{prefetch} instruction pattern |
6716 | @item @samp{prefetch} | |
e83d297b JJ |
6717 | This pattern, if defined, emits code for a non-faulting data prefetch |
6718 | instruction. Operand 0 is the address of the memory to prefetch. Operand 1 | |
6719 | is a constant 1 if the prefetch is preparing for a write to the memory | |
6720 | address, or a constant 0 otherwise. Operand 2 is the expected degree of | |
6721 | temporal locality of the data and is a value between 0 and 3, inclusive; 0 | |
6722 | means that the data has no temporal locality, so it need not be left in the | |
6723 | cache after the access; 3 means that the data has a high degree of temporal | |
6724 | locality and should be left in all levels of cache possible; 1 and 2 mean, | |
6725 | respectively, a low or moderate degree of temporal locality. | |
6726 | ||
6727 | Targets that do not support write prefetches or locality hints can ignore | |
6728 | the values of operands 1 and 2. | |
6729 | ||
b6bd3371 DE |
6730 | @cindex @code{blockage} instruction pattern |
6731 | @item @samp{blockage} | |
b6bd3371 | 6732 | This pattern defines a pseudo insn that prevents the instruction |
adddc347 HPN |
6733 | scheduler and other passes from moving instructions and using register |
6734 | equivalences across the boundary defined by the blockage insn. | |
6735 | This needs to be an UNSPEC_VOLATILE pattern or a volatile ASM. | |
b6bd3371 | 6736 | |
51ced7e4 UB |
6737 | @cindex @code{memory_blockage} instruction pattern |
6738 | @item @samp{memory_blockage} | |
6739 | This pattern, if defined, represents a compiler memory barrier, and will be | |
6740 | placed at points across which RTL passes may not propagate memory accesses. | |
6741 | This instruction needs to read and write volatile BLKmode memory. It does | |
6742 | not need to generate any machine instruction. If this pattern is not defined, | |
6743 | the compiler falls back to emitting an instruction corresponding | |
6744 | to @code{asm volatile ("" ::: "memory")}. | |
6745 | ||
48ae6c13 RH |
6746 | @cindex @code{memory_barrier} instruction pattern |
6747 | @item @samp{memory_barrier} | |
48ae6c13 RH |
6748 | If the target memory model is not fully synchronous, then this pattern |
6749 | should be defined to an instruction that orders both loads and stores | |
6750 | before the instruction with respect to loads and stores after the instruction. | |
6751 | This pattern has no operands. | |
6752 | ||
6753 | @cindex @code{sync_compare_and_swap@var{mode}} instruction pattern | |
6754 | @item @samp{sync_compare_and_swap@var{mode}} | |
48ae6c13 RH |
6755 | This pattern, if defined, emits code for an atomic compare-and-swap |
6756 | operation. Operand 1 is the memory on which the atomic operation is | |
6757 | performed. Operand 2 is the ``old'' value to be compared against the | |
6758 | current contents of the memory location. Operand 3 is the ``new'' value | |
6759 | to store in the memory if the compare succeeds. Operand 0 is the result | |
915167f5 GK |
6760 | of the operation; it should contain the contents of the memory |
6761 | before the operation. If the compare succeeds, this should obviously be | |
6762 | a copy of operand 2. | |
48ae6c13 RH |
6763 | |
6764 | This pattern must show that both operand 0 and operand 1 are modified. | |
6765 | ||
915167f5 GK |
6766 | This pattern must issue any memory barrier instructions such that all |
6767 | memory operations before the atomic operation occur before the atomic | |
6768 | operation and all memory operations after the atomic operation occur | |
6769 | after the atomic operation. | |
48ae6c13 | 6770 | |
4a77c72b | 6771 | For targets where the success or failure of the compare-and-swap |
f90b7a5a PB |
6772 | operation is available via the status flags, it is possible to |
6773 | avoid a separate compare operation and issue the subsequent | |
6774 | branch or store-flag operation immediately after the compare-and-swap. | |
6775 | To this end, GCC will look for a @code{MODE_CC} set in the | |
6776 | output of @code{sync_compare_and_swap@var{mode}}; if the machine | |
6777 | description includes such a set, the target should also define special | |
6778 | @code{cbranchcc4} and/or @code{cstorecc4} instructions. GCC will then | |
6779 | be able to take the destination of the @code{MODE_CC} set and pass it | |
6780 | to the @code{cbranchcc4} or @code{cstorecc4} pattern as the first | |
6781 | operand of the comparison (the second will be @code{(const_int 0)}). | |
48ae6c13 | 6782 | |
cedb4a1a RH |
6783 | For targets where the operating system may provide support for this |
6784 | operation via library calls, the @code{sync_compare_and_swap_optab} | |
6785 | may be initialized to a function with the same interface as the | |
6786 | @code{__sync_val_compare_and_swap_@var{n}} built-in. If the entire | |
6787 | set of @var{__sync} builtins are supported via library calls, the | |
6788 | target can initialize all of the optabs at once with | |
6789 | @code{init_sync_libfuncs}. | |
6790 | For the purposes of C++11 @code{std::atomic::is_lock_free}, it is | |
6791 | assumed that these library calls do @emph{not} use any kind of | |
6792 | interruptable locking. | |
6793 | ||
48ae6c13 RH |
6794 | @cindex @code{sync_add@var{mode}} instruction pattern |
6795 | @cindex @code{sync_sub@var{mode}} instruction pattern | |
6796 | @cindex @code{sync_ior@var{mode}} instruction pattern | |
6797 | @cindex @code{sync_and@var{mode}} instruction pattern | |
6798 | @cindex @code{sync_xor@var{mode}} instruction pattern | |
6799 | @cindex @code{sync_nand@var{mode}} instruction pattern | |
6800 | @item @samp{sync_add@var{mode}}, @samp{sync_sub@var{mode}} | |
6801 | @itemx @samp{sync_ior@var{mode}}, @samp{sync_and@var{mode}} | |
6802 | @itemx @samp{sync_xor@var{mode}}, @samp{sync_nand@var{mode}} | |
48ae6c13 RH |
6803 | These patterns emit code for an atomic operation on memory. |
6804 | Operand 0 is the memory on which the atomic operation is performed. | |
6805 | Operand 1 is the second operand to the binary operator. | |
6806 | ||
915167f5 GK |
6807 | This pattern must issue any memory barrier instructions such that all |
6808 | memory operations before the atomic operation occur before the atomic | |
6809 | operation and all memory operations after the atomic operation occur | |
6810 | after the atomic operation. | |
48ae6c13 RH |
6811 | |
6812 | If these patterns are not defined, the operation will be constructed | |
6813 | from a compare-and-swap operation, if defined. | |
6814 | ||
6815 | @cindex @code{sync_old_add@var{mode}} instruction pattern | |
6816 | @cindex @code{sync_old_sub@var{mode}} instruction pattern | |
6817 | @cindex @code{sync_old_ior@var{mode}} instruction pattern | |
6818 | @cindex @code{sync_old_and@var{mode}} instruction pattern | |
6819 | @cindex @code{sync_old_xor@var{mode}} instruction pattern | |
6820 | @cindex @code{sync_old_nand@var{mode}} instruction pattern | |
6821 | @item @samp{sync_old_add@var{mode}}, @samp{sync_old_sub@var{mode}} | |
6822 | @itemx @samp{sync_old_ior@var{mode}}, @samp{sync_old_and@var{mode}} | |
6823 | @itemx @samp{sync_old_xor@var{mode}}, @samp{sync_old_nand@var{mode}} | |
c29c1030 | 6824 | These patterns emit code for an atomic operation on memory, |
48ae6c13 RH |
6825 | and return the value that the memory contained before the operation. |
6826 | Operand 0 is the result value, operand 1 is the memory on which the | |
6827 | atomic operation is performed, and operand 2 is the second operand | |
6828 | to the binary operator. | |
6829 | ||
915167f5 GK |
6830 | This pattern must issue any memory barrier instructions such that all |
6831 | memory operations before the atomic operation occur before the atomic | |
6832 | operation and all memory operations after the atomic operation occur | |
6833 | after the atomic operation. | |
48ae6c13 RH |
6834 | |
6835 | If these patterns are not defined, the operation will be constructed | |
6836 | from a compare-and-swap operation, if defined. | |
6837 | ||
6838 | @cindex @code{sync_new_add@var{mode}} instruction pattern | |
6839 | @cindex @code{sync_new_sub@var{mode}} instruction pattern | |
6840 | @cindex @code{sync_new_ior@var{mode}} instruction pattern | |
6841 | @cindex @code{sync_new_and@var{mode}} instruction pattern | |
6842 | @cindex @code{sync_new_xor@var{mode}} instruction pattern | |
6843 | @cindex @code{sync_new_nand@var{mode}} instruction pattern | |
6844 | @item @samp{sync_new_add@var{mode}}, @samp{sync_new_sub@var{mode}} | |
6845 | @itemx @samp{sync_new_ior@var{mode}}, @samp{sync_new_and@var{mode}} | |
6846 | @itemx @samp{sync_new_xor@var{mode}}, @samp{sync_new_nand@var{mode}} | |
48ae6c13 RH |
6847 | These patterns are like their @code{sync_old_@var{op}} counterparts, |
6848 | except that they return the value that exists in the memory location | |
6849 | after the operation, rather than before the operation. | |
6850 | ||
6851 | @cindex @code{sync_lock_test_and_set@var{mode}} instruction pattern | |
6852 | @item @samp{sync_lock_test_and_set@var{mode}} | |
48ae6c13 RH |
6853 | This pattern takes two forms, based on the capabilities of the target. |
6854 | In either case, operand 0 is the result of the operand, operand 1 is | |
6855 | the memory on which the atomic operation is performed, and operand 2 | |
6856 | is the value to set in the lock. | |
6857 | ||
6858 | In the ideal case, this operation is an atomic exchange operation, in | |
6859 | which the previous value in memory operand is copied into the result | |
6860 | operand, and the value operand is stored in the memory operand. | |
6861 | ||
6862 | For less capable targets, any value operand that is not the constant 1 | |
6863 | should be rejected with @code{FAIL}. In this case the target may use | |
6864 | an atomic test-and-set bit operation. The result operand should contain | |
6865 | 1 if the bit was previously set and 0 if the bit was previously clear. | |
6866 | The true contents of the memory operand are implementation defined. | |
6867 | ||
6868 | This pattern must issue any memory barrier instructions such that the | |
915167f5 GK |
6869 | pattern as a whole acts as an acquire barrier, that is all memory |
6870 | operations after the pattern do not occur until the lock is acquired. | |
48ae6c13 RH |
6871 | |
6872 | If this pattern is not defined, the operation will be constructed from | |
6873 | a compare-and-swap operation, if defined. | |
6874 | ||
6875 | @cindex @code{sync_lock_release@var{mode}} instruction pattern | |
6876 | @item @samp{sync_lock_release@var{mode}} | |
48ae6c13 RH |
6877 | This pattern, if defined, releases a lock set by |
6878 | @code{sync_lock_test_and_set@var{mode}}. Operand 0 is the memory | |
8635a919 GK |
6879 | that contains the lock; operand 1 is the value to store in the lock. |
6880 | ||
6881 | If the target doesn't implement full semantics for | |
6882 | @code{sync_lock_test_and_set@var{mode}}, any value operand which is not | |
6883 | the constant 0 should be rejected with @code{FAIL}, and the true contents | |
6884 | of the memory operand are implementation defined. | |
48ae6c13 RH |
6885 | |
6886 | This pattern must issue any memory barrier instructions such that the | |
915167f5 GK |
6887 | pattern as a whole acts as a release barrier, that is the lock is |
6888 | released only after all previous memory operations have completed. | |
48ae6c13 RH |
6889 | |
6890 | If this pattern is not defined, then a @code{memory_barrier} pattern | |
8635a919 | 6891 | will be emitted, followed by a store of the value to the memory operand. |
48ae6c13 | 6892 | |
86951993 AM |
6893 | @cindex @code{atomic_compare_and_swap@var{mode}} instruction pattern |
6894 | @item @samp{atomic_compare_and_swap@var{mode}} | |
6895 | This pattern, if defined, emits code for an atomic compare-and-swap | |
6896 | operation with memory model semantics. Operand 2 is the memory on which | |
6897 | the atomic operation is performed. Operand 0 is an output operand which | |
6898 | is set to true or false based on whether the operation succeeded. Operand | |
6899 | 1 is an output operand which is set to the contents of the memory before | |
6900 | the operation was attempted. Operand 3 is the value that is expected to | |
6901 | be in memory. Operand 4 is the value to put in memory if the expected | |
6902 | value is found there. Operand 5 is set to 1 if this compare and swap is to | |
6903 | be treated as a weak operation. Operand 6 is the memory model to be used | |
6904 | if the operation is a success. Operand 7 is the memory model to be used | |
6905 | if the operation fails. | |
6906 | ||
6907 | If memory referred to in operand 2 contains the value in operand 3, then | |
6908 | operand 4 is stored in memory pointed to by operand 2 and fencing based on | |
6909 | the memory model in operand 6 is issued. | |
6910 | ||
6911 | If memory referred to in operand 2 does not contain the value in operand 3, | |
6912 | then fencing based on the memory model in operand 7 is issued. | |
6913 | ||
6914 | If a target does not support weak compare-and-swap operations, or the port | |
6915 | elects not to implement weak operations, the argument in operand 5 can be | |
6916 | ignored. Note a strong implementation must be provided. | |
6917 | ||
6918 | If this pattern is not provided, the @code{__atomic_compare_exchange} | |
6919 | built-in functions will utilize the legacy @code{sync_compare_and_swap} | |
6920 | pattern with an @code{__ATOMIC_SEQ_CST} memory model. | |
6921 | ||
6922 | @cindex @code{atomic_load@var{mode}} instruction pattern | |
6923 | @item @samp{atomic_load@var{mode}} | |
6924 | This pattern implements an atomic load operation with memory model | |
6925 | semantics. Operand 1 is the memory address being loaded from. Operand 0 | |
6926 | is the result of the load. Operand 2 is the memory model to be used for | |
6927 | the load operation. | |
6928 | ||
6929 | If not present, the @code{__atomic_load} built-in function will either | |
6930 | resort to a normal load with memory barriers, or a compare-and-swap | |
6931 | operation if a normal load would not be atomic. | |
6932 | ||
6933 | @cindex @code{atomic_store@var{mode}} instruction pattern | |
6934 | @item @samp{atomic_store@var{mode}} | |
6935 | This pattern implements an atomic store operation with memory model | |
6936 | semantics. Operand 0 is the memory address being stored to. Operand 1 | |
6937 | is the value to be written. Operand 2 is the memory model to be used for | |
6938 | the operation. | |
6939 | ||
6940 | If not present, the @code{__atomic_store} built-in function will attempt to | |
6941 | perform a normal store and surround it with any required memory fences. If | |
6942 | the store would not be atomic, then an @code{__atomic_exchange} is | |
6943 | attempted with the result being ignored. | |
6944 | ||
6945 | @cindex @code{atomic_exchange@var{mode}} instruction pattern | |
6946 | @item @samp{atomic_exchange@var{mode}} | |
6947 | This pattern implements an atomic exchange operation with memory model | |
6948 | semantics. Operand 1 is the memory location the operation is performed on. | |
6949 | Operand 0 is an output operand which is set to the original value contained | |
6950 | in the memory pointed to by operand 1. Operand 2 is the value to be | |
6951 | stored. Operand 3 is the memory model to be used. | |
6952 | ||
6953 | If this pattern is not present, the built-in function | |
6954 | @code{__atomic_exchange} will attempt to preform the operation with a | |
6955 | compare and swap loop. | |
6956 | ||
6957 | @cindex @code{atomic_add@var{mode}} instruction pattern | |
6958 | @cindex @code{atomic_sub@var{mode}} instruction pattern | |
6959 | @cindex @code{atomic_or@var{mode}} instruction pattern | |
6960 | @cindex @code{atomic_and@var{mode}} instruction pattern | |
6961 | @cindex @code{atomic_xor@var{mode}} instruction pattern | |
6962 | @cindex @code{atomic_nand@var{mode}} instruction pattern | |
6963 | @item @samp{atomic_add@var{mode}}, @samp{atomic_sub@var{mode}} | |
6964 | @itemx @samp{atomic_or@var{mode}}, @samp{atomic_and@var{mode}} | |
6965 | @itemx @samp{atomic_xor@var{mode}}, @samp{atomic_nand@var{mode}} | |
86951993 AM |
6966 | These patterns emit code for an atomic operation on memory with memory |
6967 | model semantics. Operand 0 is the memory on which the atomic operation is | |
6968 | performed. Operand 1 is the second operand to the binary operator. | |
6969 | Operand 2 is the memory model to be used by the operation. | |
6970 | ||
6971 | If these patterns are not defined, attempts will be made to use legacy | |
c29c1030 | 6972 | @code{sync} patterns, or equivalent patterns which return a result. If |
86951993 AM |
6973 | none of these are available a compare-and-swap loop will be used. |
6974 | ||
6975 | @cindex @code{atomic_fetch_add@var{mode}} instruction pattern | |
6976 | @cindex @code{atomic_fetch_sub@var{mode}} instruction pattern | |
6977 | @cindex @code{atomic_fetch_or@var{mode}} instruction pattern | |
6978 | @cindex @code{atomic_fetch_and@var{mode}} instruction pattern | |
6979 | @cindex @code{atomic_fetch_xor@var{mode}} instruction pattern | |
6980 | @cindex @code{atomic_fetch_nand@var{mode}} instruction pattern | |
6981 | @item @samp{atomic_fetch_add@var{mode}}, @samp{atomic_fetch_sub@var{mode}} | |
6982 | @itemx @samp{atomic_fetch_or@var{mode}}, @samp{atomic_fetch_and@var{mode}} | |
6983 | @itemx @samp{atomic_fetch_xor@var{mode}}, @samp{atomic_fetch_nand@var{mode}} | |
86951993 AM |
6984 | These patterns emit code for an atomic operation on memory with memory |
6985 | model semantics, and return the original value. Operand 0 is an output | |
6986 | operand which contains the value of the memory location before the | |
6987 | operation was performed. Operand 1 is the memory on which the atomic | |
6988 | operation is performed. Operand 2 is the second operand to the binary | |
6989 | operator. Operand 3 is the memory model to be used by the operation. | |
6990 | ||
6991 | If these patterns are not defined, attempts will be made to use legacy | |
6992 | @code{sync} patterns. If none of these are available a compare-and-swap | |
6993 | loop will be used. | |
6994 | ||
6995 | @cindex @code{atomic_add_fetch@var{mode}} instruction pattern | |
6996 | @cindex @code{atomic_sub_fetch@var{mode}} instruction pattern | |
6997 | @cindex @code{atomic_or_fetch@var{mode}} instruction pattern | |
6998 | @cindex @code{atomic_and_fetch@var{mode}} instruction pattern | |
6999 | @cindex @code{atomic_xor_fetch@var{mode}} instruction pattern | |
7000 | @cindex @code{atomic_nand_fetch@var{mode}} instruction pattern | |
7001 | @item @samp{atomic_add_fetch@var{mode}}, @samp{atomic_sub_fetch@var{mode}} | |
7002 | @itemx @samp{atomic_or_fetch@var{mode}}, @samp{atomic_and_fetch@var{mode}} | |
7003 | @itemx @samp{atomic_xor_fetch@var{mode}}, @samp{atomic_nand_fetch@var{mode}} | |
86951993 AM |
7004 | These patterns emit code for an atomic operation on memory with memory |
7005 | model semantics and return the result after the operation is performed. | |
7006 | Operand 0 is an output operand which contains the value after the | |
7007 | operation. Operand 1 is the memory on which the atomic operation is | |
7008 | performed. Operand 2 is the second operand to the binary operator. | |
7009 | Operand 3 is the memory model to be used by the operation. | |
7010 | ||
7011 | If these patterns are not defined, attempts will be made to use legacy | |
c29c1030 | 7012 | @code{sync} patterns, or equivalent patterns which return the result before |
86951993 AM |
7013 | the operation followed by the arithmetic operation required to produce the |
7014 | result. If none of these are available a compare-and-swap loop will be | |
7015 | used. | |
7016 | ||
f8a27aa6 RH |
7017 | @cindex @code{atomic_test_and_set} instruction pattern |
7018 | @item @samp{atomic_test_and_set} | |
f8a27aa6 RH |
7019 | This pattern emits code for @code{__builtin_atomic_test_and_set}. |
7020 | Operand 0 is an output operand which is set to true if the previous | |
7021 | previous contents of the byte was "set", and false otherwise. Operand 1 | |
7022 | is the @code{QImode} memory to be modified. Operand 2 is the memory | |
7023 | model to be used. | |
7024 | ||
7025 | The specific value that defines "set" is implementation defined, and | |
7026 | is normally based on what is performed by the native atomic test and set | |
7027 | instruction. | |
7028 | ||
adedd5c1 JJ |
7029 | @cindex @code{atomic_bit_test_and_set@var{mode}} instruction pattern |
7030 | @cindex @code{atomic_bit_test_and_complement@var{mode}} instruction pattern | |
7031 | @cindex @code{atomic_bit_test_and_reset@var{mode}} instruction pattern | |
7032 | @item @samp{atomic_bit_test_and_set@var{mode}} | |
7033 | @itemx @samp{atomic_bit_test_and_complement@var{mode}} | |
7034 | @itemx @samp{atomic_bit_test_and_reset@var{mode}} | |
7035 | These patterns emit code for an atomic bitwise operation on memory with memory | |
7036 | model semantics, and return the original value of the specified bit. | |
7037 | Operand 0 is an output operand which contains the value of the specified bit | |
7038 | from the memory location before the operation was performed. Operand 1 is the | |
7039 | memory on which the atomic operation is performed. Operand 2 is the bit within | |
7040 | the operand, starting with least significant bit. Operand 3 is the memory model | |
7041 | to be used by the operation. Operand 4 is a flag - it is @code{const1_rtx} | |
7042 | if operand 0 should contain the original value of the specified bit in the | |
7043 | least significant bit of the operand, and @code{const0_rtx} if the bit should | |
7044 | be in its original position in the operand. | |
7045 | @code{atomic_bit_test_and_set@var{mode}} atomically sets the specified bit after | |
7046 | remembering its original value, @code{atomic_bit_test_and_complement@var{mode}} | |
7047 | inverts the specified bit and @code{atomic_bit_test_and_reset@var{mode}} clears | |
7048 | the specified bit. | |
7049 | ||
7050 | If these patterns are not defined, attempts will be made to use | |
7051 | @code{atomic_fetch_or@var{mode}}, @code{atomic_fetch_xor@var{mode}} or | |
7052 | @code{atomic_fetch_and@var{mode}} instruction patterns, or their @code{sync} | |
7053 | counterparts. If none of these are available a compare-and-swap | |
7054 | loop will be used. | |
7055 | ||
5e5ccf0d AM |
7056 | @cindex @code{mem_thread_fence} instruction pattern |
7057 | @item @samp{mem_thread_fence} | |
86951993 AM |
7058 | This pattern emits code required to implement a thread fence with |
7059 | memory model semantics. Operand 0 is the memory model to be used. | |
7060 | ||
5e5ccf0d AM |
7061 | For the @code{__ATOMIC_RELAXED} model no instructions need to be issued |
7062 | and this expansion is not invoked. | |
7063 | ||
7064 | The compiler always emits a compiler memory barrier regardless of what | |
7065 | expanding this pattern produced. | |
7066 | ||
7067 | If this pattern is not defined, the compiler falls back to expanding the | |
7068 | @code{memory_barrier} pattern, then to emitting @code{__sync_synchronize} | |
7069 | library call, and finally to just placing a compiler memory barrier. | |
86951993 | 7070 | |
f959607b CLT |
7071 | @cindex @code{get_thread_pointer@var{mode}} instruction pattern |
7072 | @cindex @code{set_thread_pointer@var{mode}} instruction pattern | |
7073 | @item @samp{get_thread_pointer@var{mode}} | |
7074 | @itemx @samp{set_thread_pointer@var{mode}} | |
7075 | These patterns emit code that reads/sets the TLS thread pointer. Currently, | |
7076 | these are only needed if the target needs to support the | |
7077 | @code{__builtin_thread_pointer} and @code{__builtin_set_thread_pointer} | |
7078 | builtins. | |
7079 | ||
7080 | The get/set patterns have a single output/input operand respectively, | |
7081 | with @var{mode} intended to be @code{Pmode}. | |
7082 | ||
7d69de61 RH |
7083 | @cindex @code{stack_protect_set} instruction pattern |
7084 | @item @samp{stack_protect_set} | |
643e867f | 7085 | This pattern, if defined, moves a @code{ptr_mode} value from the memory |
7d69de61 RH |
7086 | in operand 1 to the memory in operand 0 without leaving the value in |
7087 | a register afterward. This is to avoid leaking the value some place | |
759915ca | 7088 | that an attacker might use to rewrite the stack guard slot after |
7d69de61 RH |
7089 | having clobbered it. |
7090 | ||
7091 | If this pattern is not defined, then a plain move pattern is generated. | |
7092 | ||
7093 | @cindex @code{stack_protect_test} instruction pattern | |
7094 | @item @samp{stack_protect_test} | |
643e867f | 7095 | This pattern, if defined, compares a @code{ptr_mode} value from the |
7d69de61 | 7096 | memory in operand 1 with the memory in operand 0 without leaving the |
3aebbe5f | 7097 | value in a register afterward and branches to operand 2 if the values |
e9d3ef3b | 7098 | were equal. |
7d69de61 | 7099 | |
3aebbe5f JJ |
7100 | If this pattern is not defined, then a plain compare pattern and |
7101 | conditional branch pattern is used. | |
7d69de61 | 7102 | |
677feb77 DD |
7103 | @cindex @code{clear_cache} instruction pattern |
7104 | @item @samp{clear_cache} | |
677feb77 DD |
7105 | This pattern, if defined, flushes the instruction cache for a region of |
7106 | memory. The region is bounded to by the Pmode pointers in operand 0 | |
7107 | inclusive and operand 1 exclusive. | |
7108 | ||
7109 | If this pattern is not defined, a call to the library function | |
7110 | @code{__clear_cache} is used. | |
7111 | ||
03dda8e3 RK |
7112 | @end table |
7113 | ||
a5249a21 HPN |
7114 | @end ifset |
7115 | @c Each of the following nodes are wrapped in separate | |
7116 | @c "@ifset INTERNALS" to work around memory limits for the default | |
7117 | @c configuration in older tetex distributions. Known to not work: | |
7118 | @c tetex-1.0.7, known to work: tetex-2.0.2. | |
7119 | @ifset INTERNALS | |
03dda8e3 RK |
7120 | @node Pattern Ordering |
7121 | @section When the Order of Patterns Matters | |
7122 | @cindex Pattern Ordering | |
7123 | @cindex Ordering of Patterns | |
7124 | ||
7125 | Sometimes an insn can match more than one instruction pattern. Then the | |
7126 | pattern that appears first in the machine description is the one used. | |
7127 | Therefore, more specific patterns (patterns that will match fewer things) | |
7128 | and faster instructions (those that will produce better code when they | |
7129 | do match) should usually go first in the description. | |
7130 | ||
7131 | In some cases the effect of ordering the patterns can be used to hide | |
7132 | a pattern when it is not valid. For example, the 68000 has an | |
7133 | instruction for converting a fullword to floating point and another | |
7134 | for converting a byte to floating point. An instruction converting | |
7135 | an integer to floating point could match either one. We put the | |
7136 | pattern to convert the fullword first to make sure that one will | |
7137 | be used rather than the other. (Otherwise a large integer might | |
7138 | be generated as a single-byte immediate quantity, which would not work.) | |
7139 | Instead of using this pattern ordering it would be possible to make the | |
7140 | pattern for convert-a-byte smart enough to deal properly with any | |
7141 | constant value. | |
7142 | ||
a5249a21 HPN |
7143 | @end ifset |
7144 | @ifset INTERNALS | |
03dda8e3 RK |
7145 | @node Dependent Patterns |
7146 | @section Interdependence of Patterns | |
7147 | @cindex Dependent Patterns | |
7148 | @cindex Interdependence of Patterns | |
7149 | ||
03dda8e3 RK |
7150 | In some cases machines support instructions identical except for the |
7151 | machine mode of one or more operands. For example, there may be | |
7152 | ``sign-extend halfword'' and ``sign-extend byte'' instructions whose | |
7153 | patterns are | |
7154 | ||
3ab51846 | 7155 | @smallexample |
03dda8e3 RK |
7156 | (set (match_operand:SI 0 @dots{}) |
7157 | (extend:SI (match_operand:HI 1 @dots{}))) | |
7158 | ||
7159 | (set (match_operand:SI 0 @dots{}) | |
7160 | (extend:SI (match_operand:QI 1 @dots{}))) | |
3ab51846 | 7161 | @end smallexample |
03dda8e3 RK |
7162 | |
7163 | @noindent | |
7164 | Constant integers do not specify a machine mode, so an instruction to | |
7165 | extend a constant value could match either pattern. The pattern it | |
7166 | actually will match is the one that appears first in the file. For correct | |
7167 | results, this must be the one for the widest possible mode (@code{HImode}, | |
7168 | here). If the pattern matches the @code{QImode} instruction, the results | |
7169 | will be incorrect if the constant value does not actually fit that mode. | |
7170 | ||
7171 | Such instructions to extend constants are rarely generated because they are | |
7172 | optimized away, but they do occasionally happen in nonoptimized | |
7173 | compilations. | |
7174 | ||
7175 | If a constraint in a pattern allows a constant, the reload pass may | |
7176 | replace a register with a constant permitted by the constraint in some | |
7177 | cases. Similarly for memory references. Because of this substitution, | |
7178 | you should not provide separate patterns for increment and decrement | |
7179 | instructions. Instead, they should be generated from the same pattern | |
7180 | that supports register-register add insns by examining the operands and | |
7181 | generating the appropriate machine instruction. | |
7182 | ||
a5249a21 HPN |
7183 | @end ifset |
7184 | @ifset INTERNALS | |
03dda8e3 RK |
7185 | @node Jump Patterns |
7186 | @section Defining Jump Instruction Patterns | |
7187 | @cindex jump instruction patterns | |
7188 | @cindex defining jump instruction patterns | |
7189 | ||
f90b7a5a PB |
7190 | GCC does not assume anything about how the machine realizes jumps. |
7191 | The machine description should define a single pattern, usually | |
7192 | a @code{define_expand}, which expands to all the required insns. | |
7193 | ||
7194 | Usually, this would be a comparison insn to set the condition code | |
7195 | and a separate branch insn testing the condition code and branching | |
7196 | or not according to its value. For many machines, however, | |
7197 | separating compares and branches is limiting, which is why the | |
7198 | more flexible approach with one @code{define_expand} is used in GCC. | |
7199 | The machine description becomes clearer for architectures that | |
7200 | have compare-and-branch instructions but no condition code. It also | |
7201 | works better when different sets of comparison operators are supported | |
7202 | by different kinds of conditional branches (e.g. integer vs. floating-point), | |
7203 | or by conditional branches with respect to conditional stores. | |
7204 | ||
7205 | Two separate insns are always used if the machine description represents | |
7206 | a condition code register using the legacy RTL expression @code{(cc0)}, | |
7207 | and on most machines that use a separate condition code register | |
7208 | (@pxref{Condition Code}). For machines that use @code{(cc0)}, in | |
7209 | fact, the set and use of the condition code must be separate and | |
7210 | adjacent@footnote{@code{note} insns can separate them, though.}, thus | |
7211 | allowing flags in @code{cc_status} to be used (@pxref{Condition Code}) and | |
7212 | so that the comparison and branch insns could be located from each other | |
7213 | by using the functions @code{prev_cc0_setter} and @code{next_cc0_user}. | |
7214 | ||
7215 | Even in this case having a single entry point for conditional branches | |
7216 | is advantageous, because it handles equally well the case where a single | |
7217 | comparison instruction records the results of both signed and unsigned | |
7218 | comparison of the given operands (with the branch insns coming in distinct | |
7219 | signed and unsigned flavors) as in the x86 or SPARC, and the case where | |
7220 | there are distinct signed and unsigned compare instructions and only | |
7221 | one set of conditional branch instructions as in the PowerPC. | |
03dda8e3 | 7222 | |
a5249a21 HPN |
7223 | @end ifset |
7224 | @ifset INTERNALS | |
6e4fcc95 MH |
7225 | @node Looping Patterns |
7226 | @section Defining Looping Instruction Patterns | |
7227 | @cindex looping instruction patterns | |
7228 | @cindex defining looping instruction patterns | |
7229 | ||
05713b80 | 7230 | Some machines have special jump instructions that can be utilized to |
6e4fcc95 MH |
7231 | make loops more efficient. A common example is the 68000 @samp{dbra} |
7232 | instruction which performs a decrement of a register and a branch if the | |
7233 | result was greater than zero. Other machines, in particular digital | |
7234 | signal processors (DSPs), have special block repeat instructions to | |
7235 | provide low-overhead loop support. For example, the TI TMS320C3x/C4x | |
7236 | DSPs have a block repeat instruction that loads special registers to | |
7237 | mark the top and end of a loop and to count the number of loop | |
7238 | iterations. This avoids the need for fetching and executing a | |
c771326b | 7239 | @samp{dbra}-like instruction and avoids pipeline stalls associated with |
6e4fcc95 MH |
7240 | the jump. |
7241 | ||
9c34dbbf ZW |
7242 | GCC has three special named patterns to support low overhead looping. |
7243 | They are @samp{decrement_and_branch_until_zero}, @samp{doloop_begin}, | |
7244 | and @samp{doloop_end}. The first pattern, | |
6e4fcc95 MH |
7245 | @samp{decrement_and_branch_until_zero}, is not emitted during RTL |
7246 | generation but may be emitted during the instruction combination phase. | |
7247 | This requires the assistance of the loop optimizer, using information | |
7248 | collected during strength reduction, to reverse a loop to count down to | |
7249 | zero. Some targets also require the loop optimizer to add a | |
7250 | @code{REG_NONNEG} note to indicate that the iteration count is always | |
7251 | positive. This is needed if the target performs a signed loop | |
7252 | termination test. For example, the 68000 uses a pattern similar to the | |
7253 | following for its @code{dbra} instruction: | |
7254 | ||
7255 | @smallexample | |
7256 | @group | |
7257 | (define_insn "decrement_and_branch_until_zero" | |
7258 | [(set (pc) | |
6ccde948 RW |
7259 | (if_then_else |
7260 | (ge (plus:SI (match_operand:SI 0 "general_operand" "+d*am") | |
7261 | (const_int -1)) | |
7262 | (const_int 0)) | |
7263 | (label_ref (match_operand 1 "" "")) | |
7264 | (pc))) | |
6e4fcc95 | 7265 | (set (match_dup 0) |
6ccde948 RW |
7266 | (plus:SI (match_dup 0) |
7267 | (const_int -1)))] | |
6e4fcc95 | 7268 | "find_reg_note (insn, REG_NONNEG, 0)" |
630d3d5a | 7269 | "@dots{}") |
6e4fcc95 MH |
7270 | @end group |
7271 | @end smallexample | |
7272 | ||
7273 | Note that since the insn is both a jump insn and has an output, it must | |
7274 | deal with its own reloads, hence the `m' constraints. Also note that | |
7275 | since this insn is generated by the instruction combination phase | |
7276 | combining two sequential insns together into an implicit parallel insn, | |
7277 | the iteration counter needs to be biased by the same amount as the | |
630d3d5a | 7278 | decrement operation, in this case @minus{}1. Note that the following similar |
6e4fcc95 MH |
7279 | pattern will not be matched by the combiner. |
7280 | ||
7281 | @smallexample | |
7282 | @group | |
7283 | (define_insn "decrement_and_branch_until_zero" | |
7284 | [(set (pc) | |
6ccde948 RW |
7285 | (if_then_else |
7286 | (ge (match_operand:SI 0 "general_operand" "+d*am") | |
7287 | (const_int 1)) | |
7288 | (label_ref (match_operand 1 "" "")) | |
7289 | (pc))) | |
6e4fcc95 | 7290 | (set (match_dup 0) |
6ccde948 RW |
7291 | (plus:SI (match_dup 0) |
7292 | (const_int -1)))] | |
6e4fcc95 | 7293 | "find_reg_note (insn, REG_NONNEG, 0)" |
630d3d5a | 7294 | "@dots{}") |
6e4fcc95 MH |
7295 | @end group |
7296 | @end smallexample | |
7297 | ||
7298 | The other two special looping patterns, @samp{doloop_begin} and | |
c21cd8b1 | 7299 | @samp{doloop_end}, are emitted by the loop optimizer for certain |
6e4fcc95 | 7300 | well-behaved loops with a finite number of loop iterations using |
ebb48a4d | 7301 | information collected during strength reduction. |
6e4fcc95 MH |
7302 | |
7303 | The @samp{doloop_end} pattern describes the actual looping instruction | |
7304 | (or the implicit looping operation) and the @samp{doloop_begin} pattern | |
c21cd8b1 | 7305 | is an optional companion pattern that can be used for initialization |
6e4fcc95 MH |
7306 | needed for some low-overhead looping instructions. |
7307 | ||
7308 | Note that some machines require the actual looping instruction to be | |
7309 | emitted at the top of the loop (e.g., the TMS320C3x/C4x DSPs). Emitting | |
7310 | the true RTL for a looping instruction at the top of the loop can cause | |
7311 | problems with flow analysis. So instead, a dummy @code{doloop} insn is | |
7312 | emitted at the end of the loop. The machine dependent reorg pass checks | |
7313 | for the presence of this @code{doloop} insn and then searches back to | |
7314 | the top of the loop, where it inserts the true looping insn (provided | |
7315 | there are no instructions in the loop which would cause problems). Any | |
7316 | additional labels can be emitted at this point. In addition, if the | |
7317 | desired special iteration counter register was not allocated, this | |
7318 | machine dependent reorg pass could emit a traditional compare and jump | |
7319 | instruction pair. | |
7320 | ||
7321 | The essential difference between the | |
7322 | @samp{decrement_and_branch_until_zero} and the @samp{doloop_end} | |
7323 | patterns is that the loop optimizer allocates an additional pseudo | |
7324 | register for the latter as an iteration counter. This pseudo register | |
7325 | cannot be used within the loop (i.e., general induction variables cannot | |
7326 | be derived from it), however, in many cases the loop induction variable | |
7327 | may become redundant and removed by the flow pass. | |
7328 | ||
7329 | ||
a5249a21 HPN |
7330 | @end ifset |
7331 | @ifset INTERNALS | |
03dda8e3 RK |
7332 | @node Insn Canonicalizations |
7333 | @section Canonicalization of Instructions | |
7334 | @cindex canonicalization of instructions | |
7335 | @cindex insn canonicalization | |
7336 | ||
7337 | There are often cases where multiple RTL expressions could represent an | |
7338 | operation performed by a single machine instruction. This situation is | |
7339 | most commonly encountered with logical, branch, and multiply-accumulate | |
7340 | instructions. In such cases, the compiler attempts to convert these | |
7341 | multiple RTL expressions into a single canonical form to reduce the | |
7342 | number of insn patterns required. | |
7343 | ||
7344 | In addition to algebraic simplifications, following canonicalizations | |
7345 | are performed: | |
7346 | ||
7347 | @itemize @bullet | |
7348 | @item | |
7349 | For commutative and comparison operators, a constant is always made the | |
7350 | second operand. If a machine only supports a constant as the second | |
7351 | operand, only patterns that match a constant in the second operand need | |
7352 | be supplied. | |
7353 | ||
e3d6e740 GK |
7354 | @item |
7355 | For associative operators, a sequence of operators will always chain | |
7356 | to the left; for instance, only the left operand of an integer @code{plus} | |
7357 | can itself be a @code{plus}. @code{and}, @code{ior}, @code{xor}, | |
7358 | @code{plus}, @code{mult}, @code{smin}, @code{smax}, @code{umin}, and | |
7359 | @code{umax} are associative when applied to integers, and sometimes to | |
7360 | floating-point. | |
7361 | ||
7362 | @item | |
03dda8e3 RK |
7363 | @cindex @code{neg}, canonicalization of |
7364 | @cindex @code{not}, canonicalization of | |
7365 | @cindex @code{mult}, canonicalization of | |
7366 | @cindex @code{plus}, canonicalization of | |
7367 | @cindex @code{minus}, canonicalization of | |
7368 | For these operators, if only one operand is a @code{neg}, @code{not}, | |
7369 | @code{mult}, @code{plus}, or @code{minus} expression, it will be the | |
7370 | first operand. | |
7371 | ||
16823694 GK |
7372 | @item |
7373 | In combinations of @code{neg}, @code{mult}, @code{plus}, and | |
7374 | @code{minus}, the @code{neg} operations (if any) will be moved inside | |
daf2f129 | 7375 | the operations as far as possible. For instance, |
16823694 | 7376 | @code{(neg (mult A B))} is canonicalized as @code{(mult (neg A) B)}, but |
9302a061 | 7377 | @code{(plus (mult (neg B) C) A)} is canonicalized as |
16823694 GK |
7378 | @code{(minus A (mult B C))}. |
7379 | ||
03dda8e3 RK |
7380 | @cindex @code{compare}, canonicalization of |
7381 | @item | |
7382 | For the @code{compare} operator, a constant is always the second operand | |
f90b7a5a | 7383 | if the first argument is a condition code register or @code{(cc0)}. |
03dda8e3 | 7384 | |
81ad201a UB |
7385 | @item |
7386 | For instructions that inherently set a condition code register, the | |
7387 | @code{compare} operator is always written as the first RTL expression of | |
7388 | the @code{parallel} instruction pattern. For example, | |
7389 | ||
7390 | @smallexample | |
7391 | (define_insn "" | |
7392 | [(set (reg:CCZ FLAGS_REG) | |
7393 | (compare:CCZ | |
7394 | (plus:SI | |
7395 | (match_operand:SI 1 "register_operand" "%r") | |
7396 | (match_operand:SI 2 "register_operand" "r")) | |
7397 | (const_int 0))) | |
7398 | (set (match_operand:SI 0 "register_operand" "=r") | |
7399 | (plus:SI (match_dup 1) (match_dup 2)))] | |
7400 | "" | |
7401 | "addl %0, %1, %2") | |
7402 | @end smallexample | |
7403 | ||
f90b7a5a | 7404 | @item |
03dda8e3 RK |
7405 | An operand of @code{neg}, @code{not}, @code{mult}, @code{plus}, or |
7406 | @code{minus} is made the first operand under the same conditions as | |
7407 | above. | |
7408 | ||
921c4418 RIL |
7409 | @item |
7410 | @code{(ltu (plus @var{a} @var{b}) @var{b})} is converted to | |
7411 | @code{(ltu (plus @var{a} @var{b}) @var{a})}. Likewise with @code{geu} instead | |
7412 | of @code{ltu}. | |
7413 | ||
03dda8e3 RK |
7414 | @item |
7415 | @code{(minus @var{x} (const_int @var{n}))} is converted to | |
7416 | @code{(plus @var{x} (const_int @var{-n}))}. | |
7417 | ||
7418 | @item | |
7419 | Within address computations (i.e., inside @code{mem}), a left shift is | |
7420 | converted into the appropriate multiplication by a power of two. | |
7421 | ||
7422 | @cindex @code{ior}, canonicalization of | |
7423 | @cindex @code{and}, canonicalization of | |
7424 | @cindex De Morgan's law | |
72938a4c | 7425 | @item |
090359d6 | 7426 | De Morgan's Law is used to move bitwise negation inside a bitwise |
03dda8e3 RK |
7427 | logical-and or logical-or operation. If this results in only one |
7428 | operand being a @code{not} expression, it will be the first one. | |
7429 | ||
7430 | A machine that has an instruction that performs a bitwise logical-and of one | |
7431 | operand with the bitwise negation of the other should specify the pattern | |
7432 | for that instruction as | |
7433 | ||
3ab51846 | 7434 | @smallexample |
03dda8e3 RK |
7435 | (define_insn "" |
7436 | [(set (match_operand:@var{m} 0 @dots{}) | |
7437 | (and:@var{m} (not:@var{m} (match_operand:@var{m} 1 @dots{})) | |
7438 | (match_operand:@var{m} 2 @dots{})))] | |
7439 | "@dots{}" | |
7440 | "@dots{}") | |
3ab51846 | 7441 | @end smallexample |
03dda8e3 RK |
7442 | |
7443 | @noindent | |
7444 | Similarly, a pattern for a ``NAND'' instruction should be written | |
7445 | ||
3ab51846 | 7446 | @smallexample |
03dda8e3 RK |
7447 | (define_insn "" |
7448 | [(set (match_operand:@var{m} 0 @dots{}) | |
7449 | (ior:@var{m} (not:@var{m} (match_operand:@var{m} 1 @dots{})) | |
7450 | (not:@var{m} (match_operand:@var{m} 2 @dots{}))))] | |
7451 | "@dots{}" | |
7452 | "@dots{}") | |
3ab51846 | 7453 | @end smallexample |
03dda8e3 RK |
7454 | |
7455 | In both cases, it is not necessary to include patterns for the many | |
7456 | logically equivalent RTL expressions. | |
7457 | ||
7458 | @cindex @code{xor}, canonicalization of | |
7459 | @item | |
7460 | The only possible RTL expressions involving both bitwise exclusive-or | |
7461 | and bitwise negation are @code{(xor:@var{m} @var{x} @var{y})} | |
bd819a4a | 7462 | and @code{(not:@var{m} (xor:@var{m} @var{x} @var{y}))}. |
03dda8e3 RK |
7463 | |
7464 | @item | |
7465 | The sum of three items, one of which is a constant, will only appear in | |
7466 | the form | |
7467 | ||
3ab51846 | 7468 | @smallexample |
03dda8e3 | 7469 | (plus:@var{m} (plus:@var{m} @var{x} @var{y}) @var{constant}) |
3ab51846 | 7470 | @end smallexample |
03dda8e3 | 7471 | |
03dda8e3 RK |
7472 | @cindex @code{zero_extract}, canonicalization of |
7473 | @cindex @code{sign_extract}, canonicalization of | |
7474 | @item | |
7475 | Equality comparisons of a group of bits (usually a single bit) with zero | |
7476 | will be written using @code{zero_extract} rather than the equivalent | |
7477 | @code{and} or @code{sign_extract} operations. | |
7478 | ||
c536876e AS |
7479 | @cindex @code{mult}, canonicalization of |
7480 | @item | |
7481 | @code{(sign_extend:@var{m1} (mult:@var{m2} (sign_extend:@var{m2} @var{x}) | |
7482 | (sign_extend:@var{m2} @var{y})))} is converted to @code{(mult:@var{m1} | |
7483 | (sign_extend:@var{m1} @var{x}) (sign_extend:@var{m1} @var{y}))}, and likewise | |
7484 | for @code{zero_extend}. | |
7485 | ||
7486 | @item | |
7487 | @code{(sign_extend:@var{m1} (mult:@var{m2} (ashiftrt:@var{m2} | |
7488 | @var{x} @var{s}) (sign_extend:@var{m2} @var{y})))} is converted | |
7489 | to @code{(mult:@var{m1} (sign_extend:@var{m1} (ashiftrt:@var{m2} | |
7490 | @var{x} @var{s})) (sign_extend:@var{m1} @var{y}))}, and likewise for | |
7491 | patterns using @code{zero_extend} and @code{lshiftrt}. If the second | |
7492 | operand of @code{mult} is also a shift, then that is extended also. | |
7493 | This transformation is only applied when it can be proven that the | |
7494 | original operation had sufficient precision to prevent overflow. | |
7495 | ||
03dda8e3 RK |
7496 | @end itemize |
7497 | ||
cd16503a HPN |
7498 | Further canonicalization rules are defined in the function |
7499 | @code{commutative_operand_precedence} in @file{gcc/rtlanal.c}. | |
7500 | ||
a5249a21 HPN |
7501 | @end ifset |
7502 | @ifset INTERNALS | |
03dda8e3 RK |
7503 | @node Expander Definitions |
7504 | @section Defining RTL Sequences for Code Generation | |
7505 | @cindex expander definitions | |
7506 | @cindex code generation RTL sequences | |
7507 | @cindex defining RTL sequences for code generation | |
7508 | ||
7509 | On some target machines, some standard pattern names for RTL generation | |
7510 | cannot be handled with single insn, but a sequence of RTL insns can | |
7511 | represent them. For these target machines, you can write a | |
161d7b59 | 7512 | @code{define_expand} to specify how to generate the sequence of RTL@. |
03dda8e3 RK |
7513 | |
7514 | @findex define_expand | |
7515 | A @code{define_expand} is an RTL expression that looks almost like a | |
7516 | @code{define_insn}; but, unlike the latter, a @code{define_expand} is used | |
7517 | only for RTL generation and it can produce more than one RTL insn. | |
7518 | ||
7519 | A @code{define_expand} RTX has four operands: | |
7520 | ||
7521 | @itemize @bullet | |
7522 | @item | |
7523 | The name. Each @code{define_expand} must have a name, since the only | |
7524 | use for it is to refer to it by name. | |
7525 | ||
03dda8e3 | 7526 | @item |
f3a3d0d3 RH |
7527 | The RTL template. This is a vector of RTL expressions representing |
7528 | a sequence of separate instructions. Unlike @code{define_insn}, there | |
7529 | is no implicit surrounding @code{PARALLEL}. | |
03dda8e3 RK |
7530 | |
7531 | @item | |
7532 | The condition, a string containing a C expression. This expression is | |
7533 | used to express how the availability of this pattern depends on | |
f0523f02 JM |
7534 | subclasses of target machine, selected by command-line options when GCC |
7535 | is run. This is just like the condition of a @code{define_insn} that | |
03dda8e3 RK |
7536 | has a standard name. Therefore, the condition (if present) may not |
7537 | depend on the data in the insn being matched, but only the | |
7538 | target-machine-type flags. The compiler needs to test these conditions | |
7539 | during initialization in order to learn exactly which named instructions | |
7540 | are available in a particular run. | |
7541 | ||
7542 | @item | |
7543 | The preparation statements, a string containing zero or more C | |
7544 | statements which are to be executed before RTL code is generated from | |
7545 | the RTL template. | |
7546 | ||
7547 | Usually these statements prepare temporary registers for use as | |
7548 | internal operands in the RTL template, but they can also generate RTL | |
7549 | insns directly by calling routines such as @code{emit_insn}, etc. | |
7550 | Any such insns precede the ones that come from the RTL template. | |
477c104e MK |
7551 | |
7552 | @item | |
7553 | Optionally, a vector containing the values of attributes. @xref{Insn | |
7554 | Attributes}. | |
03dda8e3 RK |
7555 | @end itemize |
7556 | ||
7557 | Every RTL insn emitted by a @code{define_expand} must match some | |
7558 | @code{define_insn} in the machine description. Otherwise, the compiler | |
7559 | will crash when trying to generate code for the insn or trying to optimize | |
7560 | it. | |
7561 | ||
7562 | The RTL template, in addition to controlling generation of RTL insns, | |
7563 | also describes the operands that need to be specified when this pattern | |
7564 | is used. In particular, it gives a predicate for each operand. | |
7565 | ||
7566 | A true operand, which needs to be specified in order to generate RTL from | |
7567 | the pattern, should be described with a @code{match_operand} in its first | |
7568 | occurrence in the RTL template. This enters information on the operand's | |
f0523f02 | 7569 | predicate into the tables that record such things. GCC uses the |
03dda8e3 RK |
7570 | information to preload the operand into a register if that is required for |
7571 | valid RTL code. If the operand is referred to more than once, subsequent | |
7572 | references should use @code{match_dup}. | |
7573 | ||
7574 | The RTL template may also refer to internal ``operands'' which are | |
7575 | temporary registers or labels used only within the sequence made by the | |
7576 | @code{define_expand}. Internal operands are substituted into the RTL | |
7577 | template with @code{match_dup}, never with @code{match_operand}. The | |
7578 | values of the internal operands are not passed in as arguments by the | |
7579 | compiler when it requests use of this pattern. Instead, they are computed | |
7580 | within the pattern, in the preparation statements. These statements | |
7581 | compute the values and store them into the appropriate elements of | |
7582 | @code{operands} so that @code{match_dup} can find them. | |
7583 | ||
7584 | There are two special macros defined for use in the preparation statements: | |
7585 | @code{DONE} and @code{FAIL}. Use them with a following semicolon, | |
7586 | as a statement. | |
7587 | ||
7588 | @table @code | |
7589 | ||
7590 | @findex DONE | |
7591 | @item DONE | |
7592 | Use the @code{DONE} macro to end RTL generation for the pattern. The | |
7593 | only RTL insns resulting from the pattern on this occasion will be | |
7594 | those already emitted by explicit calls to @code{emit_insn} within the | |
7595 | preparation statements; the RTL template will not be generated. | |
7596 | ||
7597 | @findex FAIL | |
7598 | @item FAIL | |
7599 | Make the pattern fail on this occasion. When a pattern fails, it means | |
7600 | that the pattern was not truly available. The calling routines in the | |
7601 | compiler will try other strategies for code generation using other patterns. | |
7602 | ||
7603 | Failure is currently supported only for binary (addition, multiplication, | |
c771326b | 7604 | shifting, etc.) and bit-field (@code{extv}, @code{extzv}, and @code{insv}) |
03dda8e3 RK |
7605 | operations. |
7606 | @end table | |
7607 | ||
55e4756f DD |
7608 | If the preparation falls through (invokes neither @code{DONE} nor |
7609 | @code{FAIL}), then the @code{define_expand} acts like a | |
7610 | @code{define_insn} in that the RTL template is used to generate the | |
7611 | insn. | |
7612 | ||
7613 | The RTL template is not used for matching, only for generating the | |
7614 | initial insn list. If the preparation statement always invokes | |
7615 | @code{DONE} or @code{FAIL}, the RTL template may be reduced to a simple | |
7616 | list of operands, such as this example: | |
7617 | ||
7618 | @smallexample | |
7619 | @group | |
7620 | (define_expand "addsi3" | |
7621 | [(match_operand:SI 0 "register_operand" "") | |
7622 | (match_operand:SI 1 "register_operand" "") | |
7623 | (match_operand:SI 2 "register_operand" "")] | |
7624 | @end group | |
7625 | @group | |
7626 | "" | |
7627 | " | |
58097133 | 7628 | @{ |
55e4756f DD |
7629 | handle_add (operands[0], operands[1], operands[2]); |
7630 | DONE; | |
58097133 | 7631 | @}") |
55e4756f DD |
7632 | @end group |
7633 | @end smallexample | |
7634 | ||
03dda8e3 RK |
7635 | Here is an example, the definition of left-shift for the SPUR chip: |
7636 | ||
7637 | @smallexample | |
7638 | @group | |
7639 | (define_expand "ashlsi3" | |
7640 | [(set (match_operand:SI 0 "register_operand" "") | |
7641 | (ashift:SI | |
7642 | @end group | |
7643 | @group | |
7644 | (match_operand:SI 1 "register_operand" "") | |
7645 | (match_operand:SI 2 "nonmemory_operand" "")))] | |
7646 | "" | |
7647 | " | |
7648 | @end group | |
7649 | @end smallexample | |
7650 | ||
7651 | @smallexample | |
7652 | @group | |
7653 | @{ | |
7654 | if (GET_CODE (operands[2]) != CONST_INT | |
7655 | || (unsigned) INTVAL (operands[2]) > 3) | |
7656 | FAIL; | |
7657 | @}") | |
7658 | @end group | |
7659 | @end smallexample | |
7660 | ||
7661 | @noindent | |
7662 | This example uses @code{define_expand} so that it can generate an RTL insn | |
7663 | for shifting when the shift-count is in the supported range of 0 to 3 but | |
7664 | fail in other cases where machine insns aren't available. When it fails, | |
7665 | the compiler tries another strategy using different patterns (such as, a | |
7666 | library call). | |
7667 | ||
7668 | If the compiler were able to handle nontrivial condition-strings in | |
7669 | patterns with names, then it would be possible to use a | |
7670 | @code{define_insn} in that case. Here is another case (zero-extension | |
7671 | on the 68000) which makes more use of the power of @code{define_expand}: | |
7672 | ||
7673 | @smallexample | |
7674 | (define_expand "zero_extendhisi2" | |
7675 | [(set (match_operand:SI 0 "general_operand" "") | |
7676 | (const_int 0)) | |
7677 | (set (strict_low_part | |
7678 | (subreg:HI | |
7679 | (match_dup 0) | |
7680 | 0)) | |
7681 | (match_operand:HI 1 "general_operand" ""))] | |
7682 | "" | |
7683 | "operands[1] = make_safe_from (operands[1], operands[0]);") | |
7684 | @end smallexample | |
7685 | ||
7686 | @noindent | |
7687 | @findex make_safe_from | |
7688 | Here two RTL insns are generated, one to clear the entire output operand | |
7689 | and the other to copy the input operand into its low half. This sequence | |
7690 | is incorrect if the input operand refers to [the old value of] the output | |
7691 | operand, so the preparation statement makes sure this isn't so. The | |
7692 | function @code{make_safe_from} copies the @code{operands[1]} into a | |
7693 | temporary register if it refers to @code{operands[0]}. It does this | |
7694 | by emitting another RTL insn. | |
7695 | ||
7696 | Finally, a third example shows the use of an internal operand. | |
7697 | Zero-extension on the SPUR chip is done by @code{and}-ing the result | |
7698 | against a halfword mask. But this mask cannot be represented by a | |
7699 | @code{const_int} because the constant value is too large to be legitimate | |
7700 | on this machine. So it must be copied into a register with | |
7701 | @code{force_reg} and then the register used in the @code{and}. | |
7702 | ||
7703 | @smallexample | |
7704 | (define_expand "zero_extendhisi2" | |
7705 | [(set (match_operand:SI 0 "register_operand" "") | |
7706 | (and:SI (subreg:SI | |
7707 | (match_operand:HI 1 "register_operand" "") | |
7708 | 0) | |
7709 | (match_dup 2)))] | |
7710 | "" | |
7711 | "operands[2] | |
3a598fbe | 7712 | = force_reg (SImode, GEN_INT (65535)); ") |
03dda8e3 RK |
7713 | @end smallexample |
7714 | ||
f4559287 | 7715 | @emph{Note:} If the @code{define_expand} is used to serve a |
c771326b | 7716 | standard binary or unary arithmetic operation or a bit-field operation, |
03dda8e3 RK |
7717 | then the last insn it generates must not be a @code{code_label}, |
7718 | @code{barrier} or @code{note}. It must be an @code{insn}, | |
7719 | @code{jump_insn} or @code{call_insn}. If you don't need a real insn | |
7720 | at the end, emit an insn to copy the result of the operation into | |
7721 | itself. Such an insn will generate no code, but it can avoid problems | |
bd819a4a | 7722 | in the compiler. |
03dda8e3 | 7723 | |
a5249a21 HPN |
7724 | @end ifset |
7725 | @ifset INTERNALS | |
03dda8e3 RK |
7726 | @node Insn Splitting |
7727 | @section Defining How to Split Instructions | |
7728 | @cindex insn splitting | |
7729 | @cindex instruction splitting | |
7730 | @cindex splitting instructions | |
7731 | ||
fae15c93 VM |
7732 | There are two cases where you should specify how to split a pattern |
7733 | into multiple insns. On machines that have instructions requiring | |
7734 | delay slots (@pxref{Delay Slots}) or that have instructions whose | |
7735 | output is not available for multiple cycles (@pxref{Processor pipeline | |
7736 | description}), the compiler phases that optimize these cases need to | |
7737 | be able to move insns into one-instruction delay slots. However, some | |
7738 | insns may generate more than one machine instruction. These insns | |
7739 | cannot be placed into a delay slot. | |
03dda8e3 RK |
7740 | |
7741 | Often you can rewrite the single insn as a list of individual insns, | |
7742 | each corresponding to one machine instruction. The disadvantage of | |
7743 | doing so is that it will cause the compilation to be slower and require | |
7744 | more space. If the resulting insns are too complex, it may also | |
7745 | suppress some optimizations. The compiler splits the insn if there is a | |
7746 | reason to believe that it might improve instruction or delay slot | |
7747 | scheduling. | |
7748 | ||
7749 | The insn combiner phase also splits putative insns. If three insns are | |
7750 | merged into one insn with a complex expression that cannot be matched by | |
7751 | some @code{define_insn} pattern, the combiner phase attempts to split | |
7752 | the complex pattern into two insns that are recognized. Usually it can | |
7753 | break the complex pattern into two patterns by splitting out some | |
7754 | subexpression. However, in some other cases, such as performing an | |
7755 | addition of a large constant in two insns on a RISC machine, the way to | |
7756 | split the addition into two insns is machine-dependent. | |
7757 | ||
f3a3d0d3 | 7758 | @findex define_split |
03dda8e3 RK |
7759 | The @code{define_split} definition tells the compiler how to split a |
7760 | complex insn into several simpler insns. It looks like this: | |
7761 | ||
7762 | @smallexample | |
7763 | (define_split | |
7764 | [@var{insn-pattern}] | |
7765 | "@var{condition}" | |
7766 | [@var{new-insn-pattern-1} | |
7767 | @var{new-insn-pattern-2} | |
7768 | @dots{}] | |
630d3d5a | 7769 | "@var{preparation-statements}") |
03dda8e3 RK |
7770 | @end smallexample |
7771 | ||
7772 | @var{insn-pattern} is a pattern that needs to be split and | |
7773 | @var{condition} is the final condition to be tested, as in a | |
7774 | @code{define_insn}. When an insn matching @var{insn-pattern} and | |
7775 | satisfying @var{condition} is found, it is replaced in the insn list | |
7776 | with the insns given by @var{new-insn-pattern-1}, | |
7777 | @var{new-insn-pattern-2}, etc. | |
7778 | ||
630d3d5a | 7779 | The @var{preparation-statements} are similar to those statements that |
03dda8e3 RK |
7780 | are specified for @code{define_expand} (@pxref{Expander Definitions}) |
7781 | and are executed before the new RTL is generated to prepare for the | |
7782 | generated code or emit some insns whose pattern is not fixed. Unlike | |
7783 | those in @code{define_expand}, however, these statements must not | |
7784 | generate any new pseudo-registers. Once reload has completed, they also | |
7785 | must not allocate any space in the stack frame. | |
7786 | ||
7787 | Patterns are matched against @var{insn-pattern} in two different | |
7788 | circumstances. If an insn needs to be split for delay slot scheduling | |
7789 | or insn scheduling, the insn is already known to be valid, which means | |
7790 | that it must have been matched by some @code{define_insn} and, if | |
df2a54e9 | 7791 | @code{reload_completed} is nonzero, is known to satisfy the constraints |
03dda8e3 RK |
7792 | of that @code{define_insn}. In that case, the new insn patterns must |
7793 | also be insns that are matched by some @code{define_insn} and, if | |
df2a54e9 | 7794 | @code{reload_completed} is nonzero, must also satisfy the constraints |
03dda8e3 RK |
7795 | of those definitions. |
7796 | ||
7797 | As an example of this usage of @code{define_split}, consider the following | |
7798 | example from @file{a29k.md}, which splits a @code{sign_extend} from | |
7799 | @code{HImode} to @code{SImode} into a pair of shift insns: | |
7800 | ||
7801 | @smallexample | |
7802 | (define_split | |
7803 | [(set (match_operand:SI 0 "gen_reg_operand" "") | |
7804 | (sign_extend:SI (match_operand:HI 1 "gen_reg_operand" "")))] | |
7805 | "" | |
7806 | [(set (match_dup 0) | |
7807 | (ashift:SI (match_dup 1) | |
7808 | (const_int 16))) | |
7809 | (set (match_dup 0) | |
7810 | (ashiftrt:SI (match_dup 0) | |
7811 | (const_int 16)))] | |
7812 | " | |
7813 | @{ operands[1] = gen_lowpart (SImode, operands[1]); @}") | |
7814 | @end smallexample | |
7815 | ||
7816 | When the combiner phase tries to split an insn pattern, it is always the | |
7817 | case that the pattern is @emph{not} matched by any @code{define_insn}. | |
7818 | The combiner pass first tries to split a single @code{set} expression | |
7819 | and then the same @code{set} expression inside a @code{parallel}, but | |
7820 | followed by a @code{clobber} of a pseudo-reg to use as a scratch | |
7821 | register. In these cases, the combiner expects exactly two new insn | |
7822 | patterns to be generated. It will verify that these patterns match some | |
7823 | @code{define_insn} definitions, so you need not do this test in the | |
7824 | @code{define_split} (of course, there is no point in writing a | |
7825 | @code{define_split} that will never produce insns that match). | |
7826 | ||
7827 | Here is an example of this use of @code{define_split}, taken from | |
7828 | @file{rs6000.md}: | |
7829 | ||
7830 | @smallexample | |
7831 | (define_split | |
7832 | [(set (match_operand:SI 0 "gen_reg_operand" "") | |
7833 | (plus:SI (match_operand:SI 1 "gen_reg_operand" "") | |
7834 | (match_operand:SI 2 "non_add_cint_operand" "")))] | |
7835 | "" | |
7836 | [(set (match_dup 0) (plus:SI (match_dup 1) (match_dup 3))) | |
7837 | (set (match_dup 0) (plus:SI (match_dup 0) (match_dup 4)))] | |
7838 | " | |
7839 | @{ | |
7840 | int low = INTVAL (operands[2]) & 0xffff; | |
7841 | int high = (unsigned) INTVAL (operands[2]) >> 16; | |
7842 | ||
7843 | if (low & 0x8000) | |
7844 | high++, low |= 0xffff0000; | |
7845 | ||
3a598fbe JL |
7846 | operands[3] = GEN_INT (high << 16); |
7847 | operands[4] = GEN_INT (low); | |
03dda8e3 RK |
7848 | @}") |
7849 | @end smallexample | |
7850 | ||
7851 | Here the predicate @code{non_add_cint_operand} matches any | |
7852 | @code{const_int} that is @emph{not} a valid operand of a single add | |
7853 | insn. The add with the smaller displacement is written so that it | |
7854 | can be substituted into the address of a subsequent operation. | |
7855 | ||
7856 | An example that uses a scratch register, from the same file, generates | |
7857 | an equality comparison of a register and a large constant: | |
7858 | ||
7859 | @smallexample | |
7860 | (define_split | |
7861 | [(set (match_operand:CC 0 "cc_reg_operand" "") | |
7862 | (compare:CC (match_operand:SI 1 "gen_reg_operand" "") | |
7863 | (match_operand:SI 2 "non_short_cint_operand" ""))) | |
7864 | (clobber (match_operand:SI 3 "gen_reg_operand" ""))] | |
7865 | "find_single_use (operands[0], insn, 0) | |
7866 | && (GET_CODE (*find_single_use (operands[0], insn, 0)) == EQ | |
7867 | || GET_CODE (*find_single_use (operands[0], insn, 0)) == NE)" | |
7868 | [(set (match_dup 3) (xor:SI (match_dup 1) (match_dup 4))) | |
7869 | (set (match_dup 0) (compare:CC (match_dup 3) (match_dup 5)))] | |
7870 | " | |
7871 | @{ | |
12bcfaa1 | 7872 | /* @r{Get the constant we are comparing against, C, and see what it |
03dda8e3 | 7873 | looks like sign-extended to 16 bits. Then see what constant |
12bcfaa1 | 7874 | could be XOR'ed with C to get the sign-extended value.} */ |
03dda8e3 RK |
7875 | |
7876 | int c = INTVAL (operands[2]); | |
7877 | int sextc = (c << 16) >> 16; | |
7878 | int xorv = c ^ sextc; | |
7879 | ||
3a598fbe JL |
7880 | operands[4] = GEN_INT (xorv); |
7881 | operands[5] = GEN_INT (sextc); | |
03dda8e3 RK |
7882 | @}") |
7883 | @end smallexample | |
7884 | ||
7885 | To avoid confusion, don't write a single @code{define_split} that | |
7886 | accepts some insns that match some @code{define_insn} as well as some | |
7887 | insns that don't. Instead, write two separate @code{define_split} | |
7888 | definitions, one for the insns that are valid and one for the insns that | |
7889 | are not valid. | |
7890 | ||
6b24c259 JH |
7891 | The splitter is allowed to split jump instructions into sequence of |
7892 | jumps or create new jumps in while splitting non-jump instructions. As | |
7893 | the central flowgraph and branch prediction information needs to be updated, | |
f282ffb3 | 7894 | several restriction apply. |
6b24c259 JH |
7895 | |
7896 | Splitting of jump instruction into sequence that over by another jump | |
c21cd8b1 | 7897 | instruction is always valid, as compiler expect identical behavior of new |
6b24c259 JH |
7898 | jump. When new sequence contains multiple jump instructions or new labels, |
7899 | more assistance is needed. Splitter is required to create only unconditional | |
7900 | jumps, or simple conditional jump instructions. Additionally it must attach a | |
63519d23 | 7901 | @code{REG_BR_PROB} note to each conditional jump. A global variable |
addd6f64 | 7902 | @code{split_branch_probability} holds the probability of the original branch in case |
e4ae5e77 | 7903 | it was a simple conditional jump, @minus{}1 otherwise. To simplify |
addd6f64 | 7904 | recomputing of edge frequencies, the new sequence is required to have only |
6b24c259 JH |
7905 | forward jumps to the newly created labels. |
7906 | ||
fae81b38 | 7907 | @findex define_insn_and_split |
c88c0d42 CP |
7908 | For the common case where the pattern of a define_split exactly matches the |
7909 | pattern of a define_insn, use @code{define_insn_and_split}. It looks like | |
7910 | this: | |
7911 | ||
7912 | @smallexample | |
7913 | (define_insn_and_split | |
7914 | [@var{insn-pattern}] | |
7915 | "@var{condition}" | |
7916 | "@var{output-template}" | |
7917 | "@var{split-condition}" | |
7918 | [@var{new-insn-pattern-1} | |
7919 | @var{new-insn-pattern-2} | |
7920 | @dots{}] | |
630d3d5a | 7921 | "@var{preparation-statements}" |
c88c0d42 CP |
7922 | [@var{insn-attributes}]) |
7923 | ||
7924 | @end smallexample | |
7925 | ||
7926 | @var{insn-pattern}, @var{condition}, @var{output-template}, and | |
7927 | @var{insn-attributes} are used as in @code{define_insn}. The | |
7928 | @var{new-insn-pattern} vector and the @var{preparation-statements} are used as | |
7929 | in a @code{define_split}. The @var{split-condition} is also used as in | |
7930 | @code{define_split}, with the additional behavior that if the condition starts | |
7931 | with @samp{&&}, the condition used for the split will be the constructed as a | |
d7d9c429 | 7932 | logical ``and'' of the split condition with the insn condition. For example, |
c88c0d42 CP |
7933 | from i386.md: |
7934 | ||
7935 | @smallexample | |
7936 | (define_insn_and_split "zero_extendhisi2_and" | |
7937 | [(set (match_operand:SI 0 "register_operand" "=r") | |
7938 | (zero_extend:SI (match_operand:HI 1 "register_operand" "0"))) | |
7939 | (clobber (reg:CC 17))] | |
7940 | "TARGET_ZERO_EXTEND_WITH_AND && !optimize_size" | |
7941 | "#" | |
7942 | "&& reload_completed" | |
f282ffb3 | 7943 | [(parallel [(set (match_dup 0) |
9c34dbbf | 7944 | (and:SI (match_dup 0) (const_int 65535))) |
6ccde948 | 7945 | (clobber (reg:CC 17))])] |
c88c0d42 CP |
7946 | "" |
7947 | [(set_attr "type" "alu1")]) | |
7948 | ||
7949 | @end smallexample | |
7950 | ||
ebb48a4d | 7951 | In this case, the actual split condition will be |
aee96fe9 | 7952 | @samp{TARGET_ZERO_EXTEND_WITH_AND && !optimize_size && reload_completed}. |
c88c0d42 CP |
7953 | |
7954 | The @code{define_insn_and_split} construction provides exactly the same | |
7955 | functionality as two separate @code{define_insn} and @code{define_split} | |
7956 | patterns. It exists for compactness, and as a maintenance tool to prevent | |
7957 | having to ensure the two patterns' templates match. | |
7958 | ||
a5249a21 HPN |
7959 | @end ifset |
7960 | @ifset INTERNALS | |
04d8aa70 AM |
7961 | @node Including Patterns |
7962 | @section Including Patterns in Machine Descriptions. | |
7963 | @cindex insn includes | |
7964 | ||
7965 | @findex include | |
7966 | The @code{include} pattern tells the compiler tools where to | |
7967 | look for patterns that are in files other than in the file | |
8a36672b | 7968 | @file{.md}. This is used only at build time and there is no preprocessing allowed. |
04d8aa70 AM |
7969 | |
7970 | It looks like: | |
7971 | ||
7972 | @smallexample | |
7973 | ||
7974 | (include | |
7975 | @var{pathname}) | |
7976 | @end smallexample | |
7977 | ||
7978 | For example: | |
7979 | ||
7980 | @smallexample | |
7981 | ||
f282ffb3 | 7982 | (include "filestuff") |
04d8aa70 AM |
7983 | |
7984 | @end smallexample | |
7985 | ||
27d30956 | 7986 | Where @var{pathname} is a string that specifies the location of the file, |
8a36672b | 7987 | specifies the include file to be in @file{gcc/config/target/filestuff}. The |
04d8aa70 AM |
7988 | directory @file{gcc/config/target} is regarded as the default directory. |
7989 | ||
7990 | ||
f282ffb3 JM |
7991 | Machine descriptions may be split up into smaller more manageable subsections |
7992 | and placed into subdirectories. | |
04d8aa70 AM |
7993 | |
7994 | By specifying: | |
7995 | ||
7996 | @smallexample | |
7997 | ||
f282ffb3 | 7998 | (include "BOGUS/filestuff") |
04d8aa70 AM |
7999 | |
8000 | @end smallexample | |
8001 | ||
8002 | the include file is specified to be in @file{gcc/config/@var{target}/BOGUS/filestuff}. | |
8003 | ||
8004 | Specifying an absolute path for the include file such as; | |
8005 | @smallexample | |
8006 | ||
f282ffb3 | 8007 | (include "/u2/BOGUS/filestuff") |
04d8aa70 AM |
8008 | |
8009 | @end smallexample | |
f282ffb3 | 8010 | is permitted but is not encouraged. |
04d8aa70 AM |
8011 | |
8012 | @subsection RTL Generation Tool Options for Directory Search | |
8013 | @cindex directory options .md | |
8014 | @cindex options, directory search | |
8015 | @cindex search options | |
8016 | ||
8017 | The @option{-I@var{dir}} option specifies directories to search for machine descriptions. | |
8018 | For example: | |
8019 | ||
8020 | @smallexample | |
8021 | ||
8022 | genrecog -I/p1/abc/proc1 -I/p2/abcd/pro2 target.md | |
8023 | ||
8024 | @end smallexample | |
8025 | ||
8026 | ||
8027 | Add the directory @var{dir} to the head of the list of directories to be | |
8028 | searched for header files. This can be used to override a system machine definition | |
8029 | file, substituting your own version, since these directories are | |
8030 | searched before the default machine description file directories. If you use more than | |
8031 | one @option{-I} option, the directories are scanned in left-to-right | |
8032 | order; the standard default directory come after. | |
8033 | ||
8034 | ||
a5249a21 HPN |
8035 | @end ifset |
8036 | @ifset INTERNALS | |
f3a3d0d3 RH |
8037 | @node Peephole Definitions |
8038 | @section Machine-Specific Peephole Optimizers | |
8039 | @cindex peephole optimizer definitions | |
8040 | @cindex defining peephole optimizers | |
8041 | ||
8042 | In addition to instruction patterns the @file{md} file may contain | |
8043 | definitions of machine-specific peephole optimizations. | |
8044 | ||
8045 | The combiner does not notice certain peephole optimizations when the data | |
8046 | flow in the program does not suggest that it should try them. For example, | |
8047 | sometimes two consecutive insns related in purpose can be combined even | |
8048 | though the second one does not appear to use a register computed in the | |
8049 | first one. A machine-specific peephole optimizer can detect such | |
8050 | opportunities. | |
8051 | ||
8052 | There are two forms of peephole definitions that may be used. The | |
8053 | original @code{define_peephole} is run at assembly output time to | |
8054 | match insns and substitute assembly text. Use of @code{define_peephole} | |
8055 | is deprecated. | |
8056 | ||
8057 | A newer @code{define_peephole2} matches insns and substitutes new | |
8058 | insns. The @code{peephole2} pass is run after register allocation | |
ebb48a4d | 8059 | but before scheduling, which may result in much better code for |
f3a3d0d3 RH |
8060 | targets that do scheduling. |
8061 | ||
8062 | @menu | |
8063 | * define_peephole:: RTL to Text Peephole Optimizers | |
8064 | * define_peephole2:: RTL to RTL Peephole Optimizers | |
8065 | @end menu | |
8066 | ||
a5249a21 HPN |
8067 | @end ifset |
8068 | @ifset INTERNALS | |
f3a3d0d3 RH |
8069 | @node define_peephole |
8070 | @subsection RTL to Text Peephole Optimizers | |
8071 | @findex define_peephole | |
8072 | ||
8073 | @need 1000 | |
8074 | A definition looks like this: | |
8075 | ||
8076 | @smallexample | |
8077 | (define_peephole | |
8078 | [@var{insn-pattern-1} | |
8079 | @var{insn-pattern-2} | |
8080 | @dots{}] | |
8081 | "@var{condition}" | |
8082 | "@var{template}" | |
630d3d5a | 8083 | "@var{optional-insn-attributes}") |
f3a3d0d3 RH |
8084 | @end smallexample |
8085 | ||
8086 | @noindent | |
8087 | The last string operand may be omitted if you are not using any | |
8088 | machine-specific information in this machine description. If present, | |
8089 | it must obey the same rules as in a @code{define_insn}. | |
8090 | ||
8091 | In this skeleton, @var{insn-pattern-1} and so on are patterns to match | |
8092 | consecutive insns. The optimization applies to a sequence of insns when | |
8093 | @var{insn-pattern-1} matches the first one, @var{insn-pattern-2} matches | |
bd819a4a | 8094 | the next, and so on. |
f3a3d0d3 RH |
8095 | |
8096 | Each of the insns matched by a peephole must also match a | |
8097 | @code{define_insn}. Peepholes are checked only at the last stage just | |
8098 | before code generation, and only optionally. Therefore, any insn which | |
8099 | would match a peephole but no @code{define_insn} will cause a crash in code | |
8100 | generation in an unoptimized compilation, or at various optimization | |
8101 | stages. | |
8102 | ||
8103 | The operands of the insns are matched with @code{match_operands}, | |
8104 | @code{match_operator}, and @code{match_dup}, as usual. What is not | |
8105 | usual is that the operand numbers apply to all the insn patterns in the | |
8106 | definition. So, you can check for identical operands in two insns by | |
8107 | using @code{match_operand} in one insn and @code{match_dup} in the | |
8108 | other. | |
8109 | ||
8110 | The operand constraints used in @code{match_operand} patterns do not have | |
8111 | any direct effect on the applicability of the peephole, but they will | |
8112 | be validated afterward, so make sure your constraints are general enough | |
8113 | to apply whenever the peephole matches. If the peephole matches | |
8114 | but the constraints are not satisfied, the compiler will crash. | |
8115 | ||
8116 | It is safe to omit constraints in all the operands of the peephole; or | |
8117 | you can write constraints which serve as a double-check on the criteria | |
8118 | previously tested. | |
8119 | ||
8120 | Once a sequence of insns matches the patterns, the @var{condition} is | |
8121 | checked. This is a C expression which makes the final decision whether to | |
8122 | perform the optimization (we do so if the expression is nonzero). If | |
8123 | @var{condition} is omitted (in other words, the string is empty) then the | |
8124 | optimization is applied to every sequence of insns that matches the | |
8125 | patterns. | |
8126 | ||
8127 | The defined peephole optimizations are applied after register allocation | |
8128 | is complete. Therefore, the peephole definition can check which | |
8129 | operands have ended up in which kinds of registers, just by looking at | |
8130 | the operands. | |
8131 | ||
8132 | @findex prev_active_insn | |
8133 | The way to refer to the operands in @var{condition} is to write | |
8134 | @code{operands[@var{i}]} for operand number @var{i} (as matched by | |
8135 | @code{(match_operand @var{i} @dots{})}). Use the variable @code{insn} | |
8136 | to refer to the last of the insns being matched; use | |
8137 | @code{prev_active_insn} to find the preceding insns. | |
8138 | ||
8139 | @findex dead_or_set_p | |
8140 | When optimizing computations with intermediate results, you can use | |
8141 | @var{condition} to match only when the intermediate results are not used | |
8142 | elsewhere. Use the C expression @code{dead_or_set_p (@var{insn}, | |
8143 | @var{op})}, where @var{insn} is the insn in which you expect the value | |
8144 | to be used for the last time (from the value of @code{insn}, together | |
8145 | with use of @code{prev_nonnote_insn}), and @var{op} is the intermediate | |
bd819a4a | 8146 | value (from @code{operands[@var{i}]}). |
f3a3d0d3 RH |
8147 | |
8148 | Applying the optimization means replacing the sequence of insns with one | |
8149 | new insn. The @var{template} controls ultimate output of assembler code | |
8150 | for this combined insn. It works exactly like the template of a | |
8151 | @code{define_insn}. Operand numbers in this template are the same ones | |
8152 | used in matching the original sequence of insns. | |
8153 | ||
8154 | The result of a defined peephole optimizer does not need to match any of | |
8155 | the insn patterns in the machine description; it does not even have an | |
8156 | opportunity to match them. The peephole optimizer definition itself serves | |
8157 | as the insn pattern to control how the insn is output. | |
8158 | ||
8159 | Defined peephole optimizers are run as assembler code is being output, | |
8160 | so the insns they produce are never combined or rearranged in any way. | |
8161 | ||
8162 | Here is an example, taken from the 68000 machine description: | |
8163 | ||
8164 | @smallexample | |
8165 | (define_peephole | |
8166 | [(set (reg:SI 15) (plus:SI (reg:SI 15) (const_int 4))) | |
8167 | (set (match_operand:DF 0 "register_operand" "=f") | |
8168 | (match_operand:DF 1 "register_operand" "ad"))] | |
8169 | "FP_REG_P (operands[0]) && ! FP_REG_P (operands[1])" | |
f3a3d0d3 RH |
8170 | @{ |
8171 | rtx xoperands[2]; | |
a2a8cc44 | 8172 | xoperands[1] = gen_rtx_REG (SImode, REGNO (operands[1]) + 1); |
f3a3d0d3 | 8173 | #ifdef MOTOROLA |
0f40f9f7 ZW |
8174 | output_asm_insn ("move.l %1,(sp)", xoperands); |
8175 | output_asm_insn ("move.l %1,-(sp)", operands); | |
8176 | return "fmove.d (sp)+,%0"; | |
f3a3d0d3 | 8177 | #else |
0f40f9f7 ZW |
8178 | output_asm_insn ("movel %1,sp@@", xoperands); |
8179 | output_asm_insn ("movel %1,sp@@-", operands); | |
8180 | return "fmoved sp@@+,%0"; | |
f3a3d0d3 | 8181 | #endif |
0f40f9f7 | 8182 | @}) |
f3a3d0d3 RH |
8183 | @end smallexample |
8184 | ||
8185 | @need 1000 | |
8186 | The effect of this optimization is to change | |
8187 | ||
8188 | @smallexample | |
8189 | @group | |
8190 | jbsr _foobar | |
8191 | addql #4,sp | |
8192 | movel d1,sp@@- | |
8193 | movel d0,sp@@- | |
8194 | fmoved sp@@+,fp0 | |
8195 | @end group | |
8196 | @end smallexample | |
8197 | ||
8198 | @noindent | |
8199 | into | |
8200 | ||
8201 | @smallexample | |
8202 | @group | |
8203 | jbsr _foobar | |
8204 | movel d1,sp@@ | |
8205 | movel d0,sp@@- | |
8206 | fmoved sp@@+,fp0 | |
8207 | @end group | |
8208 | @end smallexample | |
8209 | ||
8210 | @ignore | |
8211 | @findex CC_REVERSED | |
8212 | If a peephole matches a sequence including one or more jump insns, you must | |
8213 | take account of the flags such as @code{CC_REVERSED} which specify that the | |
8214 | condition codes are represented in an unusual manner. The compiler | |
8215 | automatically alters any ordinary conditional jumps which occur in such | |
8216 | situations, but the compiler cannot alter jumps which have been replaced by | |
8217 | peephole optimizations. So it is up to you to alter the assembler code | |
8218 | that the peephole produces. Supply C code to write the assembler output, | |
8219 | and in this C code check the condition code status flags and change the | |
8220 | assembler code as appropriate. | |
8221 | @end ignore | |
8222 | ||
8223 | @var{insn-pattern-1} and so on look @emph{almost} like the second | |
8224 | operand of @code{define_insn}. There is one important difference: the | |
8225 | second operand of @code{define_insn} consists of one or more RTX's | |
8226 | enclosed in square brackets. Usually, there is only one: then the same | |
8227 | action can be written as an element of a @code{define_peephole}. But | |
8228 | when there are multiple actions in a @code{define_insn}, they are | |
8229 | implicitly enclosed in a @code{parallel}. Then you must explicitly | |
8230 | write the @code{parallel}, and the square brackets within it, in the | |
8231 | @code{define_peephole}. Thus, if an insn pattern looks like this, | |
8232 | ||
8233 | @smallexample | |
8234 | (define_insn "divmodsi4" | |
8235 | [(set (match_operand:SI 0 "general_operand" "=d") | |
8236 | (div:SI (match_operand:SI 1 "general_operand" "0") | |
8237 | (match_operand:SI 2 "general_operand" "dmsK"))) | |
8238 | (set (match_operand:SI 3 "general_operand" "=d") | |
8239 | (mod:SI (match_dup 1) (match_dup 2)))] | |
8240 | "TARGET_68020" | |
8241 | "divsl%.l %2,%3:%0") | |
8242 | @end smallexample | |
8243 | ||
8244 | @noindent | |
8245 | then the way to mention this insn in a peephole is as follows: | |
8246 | ||
8247 | @smallexample | |
8248 | (define_peephole | |
8249 | [@dots{} | |
8250 | (parallel | |
8251 | [(set (match_operand:SI 0 "general_operand" "=d") | |
8252 | (div:SI (match_operand:SI 1 "general_operand" "0") | |
8253 | (match_operand:SI 2 "general_operand" "dmsK"))) | |
8254 | (set (match_operand:SI 3 "general_operand" "=d") | |
8255 | (mod:SI (match_dup 1) (match_dup 2)))]) | |
8256 | @dots{}] | |
8257 | @dots{}) | |
8258 | @end smallexample | |
8259 | ||
a5249a21 HPN |
8260 | @end ifset |
8261 | @ifset INTERNALS | |
f3a3d0d3 RH |
8262 | @node define_peephole2 |
8263 | @subsection RTL to RTL Peephole Optimizers | |
8264 | @findex define_peephole2 | |
8265 | ||
8266 | The @code{define_peephole2} definition tells the compiler how to | |
ebb48a4d | 8267 | substitute one sequence of instructions for another sequence, |
f3a3d0d3 RH |
8268 | what additional scratch registers may be needed and what their |
8269 | lifetimes must be. | |
8270 | ||
8271 | @smallexample | |
8272 | (define_peephole2 | |
8273 | [@var{insn-pattern-1} | |
8274 | @var{insn-pattern-2} | |
8275 | @dots{}] | |
8276 | "@var{condition}" | |
8277 | [@var{new-insn-pattern-1} | |
8278 | @var{new-insn-pattern-2} | |
8279 | @dots{}] | |
630d3d5a | 8280 | "@var{preparation-statements}") |
f3a3d0d3 RH |
8281 | @end smallexample |
8282 | ||
8283 | The definition is almost identical to @code{define_split} | |
8284 | (@pxref{Insn Splitting}) except that the pattern to match is not a | |
8285 | single instruction, but a sequence of instructions. | |
8286 | ||
8287 | It is possible to request additional scratch registers for use in the | |
8288 | output template. If appropriate registers are not free, the pattern | |
8289 | will simply not match. | |
8290 | ||
8291 | @findex match_scratch | |
8292 | @findex match_dup | |
8293 | Scratch registers are requested with a @code{match_scratch} pattern at | |
8294 | the top level of the input pattern. The allocated register (initially) will | |
8295 | be dead at the point requested within the original sequence. If the scratch | |
8296 | is used at more than a single point, a @code{match_dup} pattern at the | |
8297 | top level of the input pattern marks the last position in the input sequence | |
8298 | at which the register must be available. | |
8299 | ||
8300 | Here is an example from the IA-32 machine description: | |
8301 | ||
8302 | @smallexample | |
8303 | (define_peephole2 | |
8304 | [(match_scratch:SI 2 "r") | |
8305 | (parallel [(set (match_operand:SI 0 "register_operand" "") | |
8306 | (match_operator:SI 3 "arith_or_logical_operator" | |
8307 | [(match_dup 0) | |
8308 | (match_operand:SI 1 "memory_operand" "")])) | |
8309 | (clobber (reg:CC 17))])] | |
8310 | "! optimize_size && ! TARGET_READ_MODIFY" | |
8311 | [(set (match_dup 2) (match_dup 1)) | |
8312 | (parallel [(set (match_dup 0) | |
8313 | (match_op_dup 3 [(match_dup 0) (match_dup 2)])) | |
8314 | (clobber (reg:CC 17))])] | |
8315 | "") | |
8316 | @end smallexample | |
8317 | ||
8318 | @noindent | |
8319 | This pattern tries to split a load from its use in the hopes that we'll be | |
8320 | able to schedule around the memory load latency. It allocates a single | |
8321 | @code{SImode} register of class @code{GENERAL_REGS} (@code{"r"}) that needs | |
8322 | to be live only at the point just before the arithmetic. | |
8323 | ||
b192711e | 8324 | A real example requiring extended scratch lifetimes is harder to come by, |
f3a3d0d3 RH |
8325 | so here's a silly made-up example: |
8326 | ||
8327 | @smallexample | |
8328 | (define_peephole2 | |
8329 | [(match_scratch:SI 4 "r") | |
8330 | (set (match_operand:SI 0 "" "") (match_operand:SI 1 "" "")) | |
8331 | (set (match_operand:SI 2 "" "") (match_dup 1)) | |
8332 | (match_dup 4) | |
8333 | (set (match_operand:SI 3 "" "") (match_dup 1))] | |
630d3d5a | 8334 | "/* @r{determine 1 does not overlap 0 and 2} */" |
f3a3d0d3 RH |
8335 | [(set (match_dup 4) (match_dup 1)) |
8336 | (set (match_dup 0) (match_dup 4)) | |
c8fbf1fa | 8337 | (set (match_dup 2) (match_dup 4)) |
f3a3d0d3 RH |
8338 | (set (match_dup 3) (match_dup 4))] |
8339 | "") | |
8340 | @end smallexample | |
8341 | ||
8342 | @noindent | |
a628d195 RH |
8343 | If we had not added the @code{(match_dup 4)} in the middle of the input |
8344 | sequence, it might have been the case that the register we chose at the | |
8345 | beginning of the sequence is killed by the first or second @code{set}. | |
f3a3d0d3 | 8346 | |
a5249a21 HPN |
8347 | @end ifset |
8348 | @ifset INTERNALS | |
03dda8e3 RK |
8349 | @node Insn Attributes |
8350 | @section Instruction Attributes | |
8351 | @cindex insn attributes | |
8352 | @cindex instruction attributes | |
8353 | ||
8354 | In addition to describing the instruction supported by the target machine, | |
8355 | the @file{md} file also defines a group of @dfn{attributes} and a set of | |
8356 | values for each. Every generated insn is assigned a value for each attribute. | |
8357 | One possible attribute would be the effect that the insn has on the machine's | |
8358 | condition code. This attribute can then be used by @code{NOTICE_UPDATE_CC} | |
8359 | to track the condition codes. | |
8360 | ||
8361 | @menu | |
8362 | * Defining Attributes:: Specifying attributes and their values. | |
8363 | * Expressions:: Valid expressions for attribute values. | |
8364 | * Tagging Insns:: Assigning attribute values to insns. | |
8365 | * Attr Example:: An example of assigning attributes. | |
8366 | * Insn Lengths:: Computing the length of insns. | |
8367 | * Constant Attributes:: Defining attributes that are constant. | |
13b72c22 | 8368 | * Mnemonic Attribute:: Obtain the instruction mnemonic as attribute value. |
03dda8e3 | 8369 | * Delay Slots:: Defining delay slots required for a machine. |
fae15c93 | 8370 | * Processor pipeline description:: Specifying information for insn scheduling. |
03dda8e3 RK |
8371 | @end menu |
8372 | ||
a5249a21 HPN |
8373 | @end ifset |
8374 | @ifset INTERNALS | |
03dda8e3 RK |
8375 | @node Defining Attributes |
8376 | @subsection Defining Attributes and their Values | |
8377 | @cindex defining attributes and their values | |
8378 | @cindex attributes, defining | |
8379 | ||
8380 | @findex define_attr | |
8381 | The @code{define_attr} expression is used to define each attribute required | |
8382 | by the target machine. It looks like: | |
8383 | ||
8384 | @smallexample | |
8385 | (define_attr @var{name} @var{list-of-values} @var{default}) | |
8386 | @end smallexample | |
8387 | ||
13b72c22 AK |
8388 | @var{name} is a string specifying the name of the attribute being |
8389 | defined. Some attributes are used in a special way by the rest of the | |
8390 | compiler. The @code{enabled} attribute can be used to conditionally | |
8391 | enable or disable insn alternatives (@pxref{Disable Insn | |
8392 | Alternatives}). The @code{predicable} attribute, together with a | |
8393 | suitable @code{define_cond_exec} (@pxref{Conditional Execution}), can | |
8394 | be used to automatically generate conditional variants of instruction | |
8395 | patterns. The @code{mnemonic} attribute can be used to check for the | |
8396 | instruction mnemonic (@pxref{Mnemonic Attribute}). The compiler | |
8397 | internally uses the names @code{ce_enabled} and @code{nonce_enabled}, | |
8398 | so they should not be used elsewhere as alternative names. | |
03dda8e3 RK |
8399 | |
8400 | @var{list-of-values} is either a string that specifies a comma-separated | |
8401 | list of values that can be assigned to the attribute, or a null string to | |
8402 | indicate that the attribute takes numeric values. | |
8403 | ||
8404 | @var{default} is an attribute expression that gives the value of this | |
8405 | attribute for insns that match patterns whose definition does not include | |
8406 | an explicit value for this attribute. @xref{Attr Example}, for more | |
8407 | information on the handling of defaults. @xref{Constant Attributes}, | |
8408 | for information on attributes that do not depend on any particular insn. | |
8409 | ||
8410 | @findex insn-attr.h | |
8411 | For each defined attribute, a number of definitions are written to the | |
8412 | @file{insn-attr.h} file. For cases where an explicit set of values is | |
8413 | specified for an attribute, the following are defined: | |
8414 | ||
8415 | @itemize @bullet | |
8416 | @item | |
8417 | A @samp{#define} is written for the symbol @samp{HAVE_ATTR_@var{name}}. | |
8418 | ||
8419 | @item | |
2eac577f | 8420 | An enumerated class is defined for @samp{attr_@var{name}} with |
03dda8e3 | 8421 | elements of the form @samp{@var{upper-name}_@var{upper-value}} where |
4bd0bee9 | 8422 | the attribute name and value are first converted to uppercase. |
03dda8e3 RK |
8423 | |
8424 | @item | |
8425 | A function @samp{get_attr_@var{name}} is defined that is passed an insn and | |
8426 | returns the attribute value for that insn. | |
8427 | @end itemize | |
8428 | ||
8429 | For example, if the following is present in the @file{md} file: | |
8430 | ||
8431 | @smallexample | |
8432 | (define_attr "type" "branch,fp,load,store,arith" @dots{}) | |
8433 | @end smallexample | |
8434 | ||
8435 | @noindent | |
8436 | the following lines will be written to the file @file{insn-attr.h}. | |
8437 | ||
8438 | @smallexample | |
d327457f | 8439 | #define HAVE_ATTR_type 1 |
03dda8e3 RK |
8440 | enum attr_type @{TYPE_BRANCH, TYPE_FP, TYPE_LOAD, |
8441 | TYPE_STORE, TYPE_ARITH@}; | |
8442 | extern enum attr_type get_attr_type (); | |
8443 | @end smallexample | |
8444 | ||
8445 | If the attribute takes numeric values, no @code{enum} type will be | |
8446 | defined and the function to obtain the attribute's value will return | |
8447 | @code{int}. | |
8448 | ||
7ac28727 AK |
8449 | There are attributes which are tied to a specific meaning. These |
8450 | attributes are not free to use for other purposes: | |
8451 | ||
8452 | @table @code | |
8453 | @item length | |
8454 | The @code{length} attribute is used to calculate the length of emitted | |
8455 | code chunks. This is especially important when verifying branch | |
8456 | distances. @xref{Insn Lengths}. | |
8457 | ||
8458 | @item enabled | |
8459 | The @code{enabled} attribute can be defined to prevent certain | |
8460 | alternatives of an insn definition from being used during code | |
8461 | generation. @xref{Disable Insn Alternatives}. | |
13b72c22 AK |
8462 | |
8463 | @item mnemonic | |
8464 | The @code{mnemonic} attribute can be defined to implement instruction | |
8465 | specific checks in e.g. the pipeline description. | |
8466 | @xref{Mnemonic Attribute}. | |
7ac28727 AK |
8467 | @end table |
8468 | ||
d327457f JR |
8469 | For each of these special attributes, the corresponding |
8470 | @samp{HAVE_ATTR_@var{name}} @samp{#define} is also written when the | |
8471 | attribute is not defined; in that case, it is defined as @samp{0}. | |
8472 | ||
8f4fe86c RS |
8473 | @findex define_enum_attr |
8474 | @anchor{define_enum_attr} | |
8475 | Another way of defining an attribute is to use: | |
8476 | ||
8477 | @smallexample | |
8478 | (define_enum_attr "@var{attr}" "@var{enum}" @var{default}) | |
8479 | @end smallexample | |
8480 | ||
8481 | This works in just the same way as @code{define_attr}, except that | |
8482 | the list of values is taken from a separate enumeration called | |
8483 | @var{enum} (@pxref{define_enum}). This form allows you to use | |
8484 | the same list of values for several attributes without having to | |
8485 | repeat the list each time. For example: | |
8486 | ||
8487 | @smallexample | |
8488 | (define_enum "processor" [ | |
8489 | model_a | |
8490 | model_b | |
8491 | @dots{} | |
8492 | ]) | |
8493 | (define_enum_attr "arch" "processor" | |
8494 | (const (symbol_ref "target_arch"))) | |
8495 | (define_enum_attr "tune" "processor" | |
8496 | (const (symbol_ref "target_tune"))) | |
8497 | @end smallexample | |
8498 | ||
8499 | defines the same attributes as: | |
8500 | ||
8501 | @smallexample | |
8502 | (define_attr "arch" "model_a,model_b,@dots{}" | |
8503 | (const (symbol_ref "target_arch"))) | |
8504 | (define_attr "tune" "model_a,model_b,@dots{}" | |
8505 | (const (symbol_ref "target_tune"))) | |
8506 | @end smallexample | |
8507 | ||
8508 | but without duplicating the processor list. The second example defines two | |
8509 | separate C enums (@code{attr_arch} and @code{attr_tune}) whereas the first | |
8510 | defines a single C enum (@code{processor}). | |
a5249a21 HPN |
8511 | @end ifset |
8512 | @ifset INTERNALS | |
03dda8e3 RK |
8513 | @node Expressions |
8514 | @subsection Attribute Expressions | |
8515 | @cindex attribute expressions | |
8516 | ||
8517 | RTL expressions used to define attributes use the codes described above | |
8518 | plus a few specific to attribute definitions, to be discussed below. | |
8519 | Attribute value expressions must have one of the following forms: | |
8520 | ||
8521 | @table @code | |
8522 | @cindex @code{const_int} and attributes | |
8523 | @item (const_int @var{i}) | |
8524 | The integer @var{i} specifies the value of a numeric attribute. @var{i} | |
8525 | must be non-negative. | |
8526 | ||
8527 | The value of a numeric attribute can be specified either with a | |
00bc45c1 RH |
8528 | @code{const_int}, or as an integer represented as a string in |
8529 | @code{const_string}, @code{eq_attr} (see below), @code{attr}, | |
8530 | @code{symbol_ref}, simple arithmetic expressions, and @code{set_attr} | |
8531 | overrides on specific instructions (@pxref{Tagging Insns}). | |
03dda8e3 RK |
8532 | |
8533 | @cindex @code{const_string} and attributes | |
8534 | @item (const_string @var{value}) | |
8535 | The string @var{value} specifies a constant attribute value. | |
8536 | If @var{value} is specified as @samp{"*"}, it means that the default value of | |
8537 | the attribute is to be used for the insn containing this expression. | |
8538 | @samp{"*"} obviously cannot be used in the @var{default} expression | |
bd819a4a | 8539 | of a @code{define_attr}. |
03dda8e3 RK |
8540 | |
8541 | If the attribute whose value is being specified is numeric, @var{value} | |
8542 | must be a string containing a non-negative integer (normally | |
8543 | @code{const_int} would be used in this case). Otherwise, it must | |
8544 | contain one of the valid values for the attribute. | |
8545 | ||
8546 | @cindex @code{if_then_else} and attributes | |
8547 | @item (if_then_else @var{test} @var{true-value} @var{false-value}) | |
8548 | @var{test} specifies an attribute test, whose format is defined below. | |
8549 | The value of this expression is @var{true-value} if @var{test} is true, | |
8550 | otherwise it is @var{false-value}. | |
8551 | ||
8552 | @cindex @code{cond} and attributes | |
8553 | @item (cond [@var{test1} @var{value1} @dots{}] @var{default}) | |
8554 | The first operand of this expression is a vector containing an even | |
8555 | number of expressions and consisting of pairs of @var{test} and @var{value} | |
8556 | expressions. The value of the @code{cond} expression is that of the | |
8557 | @var{value} corresponding to the first true @var{test} expression. If | |
8558 | none of the @var{test} expressions are true, the value of the @code{cond} | |
8559 | expression is that of the @var{default} expression. | |
8560 | @end table | |
8561 | ||
8562 | @var{test} expressions can have one of the following forms: | |
8563 | ||
8564 | @table @code | |
8565 | @cindex @code{const_int} and attribute tests | |
8566 | @item (const_int @var{i}) | |
df2a54e9 | 8567 | This test is true if @var{i} is nonzero and false otherwise. |
03dda8e3 RK |
8568 | |
8569 | @cindex @code{not} and attributes | |
8570 | @cindex @code{ior} and attributes | |
8571 | @cindex @code{and} and attributes | |
8572 | @item (not @var{test}) | |
8573 | @itemx (ior @var{test1} @var{test2}) | |
8574 | @itemx (and @var{test1} @var{test2}) | |
8575 | These tests are true if the indicated logical function is true. | |
8576 | ||
8577 | @cindex @code{match_operand} and attributes | |
8578 | @item (match_operand:@var{m} @var{n} @var{pred} @var{constraints}) | |
8579 | This test is true if operand @var{n} of the insn whose attribute value | |
8580 | is being determined has mode @var{m} (this part of the test is ignored | |
8581 | if @var{m} is @code{VOIDmode}) and the function specified by the string | |
df2a54e9 | 8582 | @var{pred} returns a nonzero value when passed operand @var{n} and mode |
03dda8e3 RK |
8583 | @var{m} (this part of the test is ignored if @var{pred} is the null |
8584 | string). | |
8585 | ||
8586 | The @var{constraints} operand is ignored and should be the null string. | |
8587 | ||
0c0d3957 RS |
8588 | @cindex @code{match_test} and attributes |
8589 | @item (match_test @var{c-expr}) | |
8590 | The test is true if C expression @var{c-expr} is true. In non-constant | |
8591 | attributes, @var{c-expr} has access to the following variables: | |
8592 | ||
8593 | @table @var | |
8594 | @item insn | |
8595 | The rtl instruction under test. | |
8596 | @item which_alternative | |
8597 | The @code{define_insn} alternative that @var{insn} matches. | |
8598 | @xref{Output Statement}. | |
8599 | @item operands | |
8600 | An array of @var{insn}'s rtl operands. | |
8601 | @end table | |
8602 | ||
8603 | @var{c-expr} behaves like the condition in a C @code{if} statement, | |
8604 | so there is no need to explicitly convert the expression into a boolean | |
8605 | 0 or 1 value. For example, the following two tests are equivalent: | |
8606 | ||
8607 | @smallexample | |
8608 | (match_test "x & 2") | |
8609 | (match_test "(x & 2) != 0") | |
8610 | @end smallexample | |
8611 | ||
03dda8e3 RK |
8612 | @cindex @code{le} and attributes |
8613 | @cindex @code{leu} and attributes | |
8614 | @cindex @code{lt} and attributes | |
8615 | @cindex @code{gt} and attributes | |
8616 | @cindex @code{gtu} and attributes | |
8617 | @cindex @code{ge} and attributes | |
8618 | @cindex @code{geu} and attributes | |
8619 | @cindex @code{ne} and attributes | |
8620 | @cindex @code{eq} and attributes | |
8621 | @cindex @code{plus} and attributes | |
8622 | @cindex @code{minus} and attributes | |
8623 | @cindex @code{mult} and attributes | |
8624 | @cindex @code{div} and attributes | |
8625 | @cindex @code{mod} and attributes | |
8626 | @cindex @code{abs} and attributes | |
8627 | @cindex @code{neg} and attributes | |
8628 | @cindex @code{ashift} and attributes | |
8629 | @cindex @code{lshiftrt} and attributes | |
8630 | @cindex @code{ashiftrt} and attributes | |
8631 | @item (le @var{arith1} @var{arith2}) | |
8632 | @itemx (leu @var{arith1} @var{arith2}) | |
8633 | @itemx (lt @var{arith1} @var{arith2}) | |
8634 | @itemx (ltu @var{arith1} @var{arith2}) | |
8635 | @itemx (gt @var{arith1} @var{arith2}) | |
8636 | @itemx (gtu @var{arith1} @var{arith2}) | |
8637 | @itemx (ge @var{arith1} @var{arith2}) | |
8638 | @itemx (geu @var{arith1} @var{arith2}) | |
8639 | @itemx (ne @var{arith1} @var{arith2}) | |
8640 | @itemx (eq @var{arith1} @var{arith2}) | |
8641 | These tests are true if the indicated comparison of the two arithmetic | |
8642 | expressions is true. Arithmetic expressions are formed with | |
8643 | @code{plus}, @code{minus}, @code{mult}, @code{div}, @code{mod}, | |
8644 | @code{abs}, @code{neg}, @code{and}, @code{ior}, @code{xor}, @code{not}, | |
bd819a4a | 8645 | @code{ashift}, @code{lshiftrt}, and @code{ashiftrt} expressions. |
03dda8e3 RK |
8646 | |
8647 | @findex get_attr | |
8648 | @code{const_int} and @code{symbol_ref} are always valid terms (@pxref{Insn | |
8649 | Lengths},for additional forms). @code{symbol_ref} is a string | |
8650 | denoting a C expression that yields an @code{int} when evaluated by the | |
8651 | @samp{get_attr_@dots{}} routine. It should normally be a global | |
bd819a4a | 8652 | variable. |
03dda8e3 RK |
8653 | |
8654 | @findex eq_attr | |
8655 | @item (eq_attr @var{name} @var{value}) | |
8656 | @var{name} is a string specifying the name of an attribute. | |
8657 | ||
8658 | @var{value} is a string that is either a valid value for attribute | |
8659 | @var{name}, a comma-separated list of values, or @samp{!} followed by a | |
8660 | value or list. If @var{value} does not begin with a @samp{!}, this | |
8661 | test is true if the value of the @var{name} attribute of the current | |
8662 | insn is in the list specified by @var{value}. If @var{value} begins | |
8663 | with a @samp{!}, this test is true if the attribute's value is | |
8664 | @emph{not} in the specified list. | |
8665 | ||
8666 | For example, | |
8667 | ||
8668 | @smallexample | |
8669 | (eq_attr "type" "load,store") | |
8670 | @end smallexample | |
8671 | ||
8672 | @noindent | |
8673 | is equivalent to | |
8674 | ||
8675 | @smallexample | |
8676 | (ior (eq_attr "type" "load") (eq_attr "type" "store")) | |
8677 | @end smallexample | |
8678 | ||
8679 | If @var{name} specifies an attribute of @samp{alternative}, it refers to the | |
8680 | value of the compiler variable @code{which_alternative} | |
8681 | (@pxref{Output Statement}) and the values must be small integers. For | |
bd819a4a | 8682 | example, |
03dda8e3 RK |
8683 | |
8684 | @smallexample | |
8685 | (eq_attr "alternative" "2,3") | |
8686 | @end smallexample | |
8687 | ||
8688 | @noindent | |
8689 | is equivalent to | |
8690 | ||
8691 | @smallexample | |
8692 | (ior (eq (symbol_ref "which_alternative") (const_int 2)) | |
8693 | (eq (symbol_ref "which_alternative") (const_int 3))) | |
8694 | @end smallexample | |
8695 | ||
8696 | Note that, for most attributes, an @code{eq_attr} test is simplified in cases | |
8697 | where the value of the attribute being tested is known for all insns matching | |
bd819a4a | 8698 | a particular pattern. This is by far the most common case. |
03dda8e3 RK |
8699 | |
8700 | @findex attr_flag | |
8701 | @item (attr_flag @var{name}) | |
8702 | The value of an @code{attr_flag} expression is true if the flag | |
8703 | specified by @var{name} is true for the @code{insn} currently being | |
8704 | scheduled. | |
8705 | ||
8706 | @var{name} is a string specifying one of a fixed set of flags to test. | |
8707 | Test the flags @code{forward} and @code{backward} to determine the | |
81e7aa8e | 8708 | direction of a conditional branch. |
03dda8e3 RK |
8709 | |
8710 | This example describes a conditional branch delay slot which | |
8711 | can be nullified for forward branches that are taken (annul-true) or | |
8712 | for backward branches which are not taken (annul-false). | |
8713 | ||
8714 | @smallexample | |
8715 | (define_delay (eq_attr "type" "cbranch") | |
8716 | [(eq_attr "in_branch_delay" "true") | |
8717 | (and (eq_attr "in_branch_delay" "true") | |
8718 | (attr_flag "forward")) | |
8719 | (and (eq_attr "in_branch_delay" "true") | |
8720 | (attr_flag "backward"))]) | |
8721 | @end smallexample | |
8722 | ||
8723 | The @code{forward} and @code{backward} flags are false if the current | |
8724 | @code{insn} being scheduled is not a conditional branch. | |
8725 | ||
03dda8e3 RK |
8726 | @code{attr_flag} is only used during delay slot scheduling and has no |
8727 | meaning to other passes of the compiler. | |
00bc45c1 RH |
8728 | |
8729 | @findex attr | |
8730 | @item (attr @var{name}) | |
8731 | The value of another attribute is returned. This is most useful | |
8732 | for numeric attributes, as @code{eq_attr} and @code{attr_flag} | |
8733 | produce more efficient code for non-numeric attributes. | |
03dda8e3 RK |
8734 | @end table |
8735 | ||
a5249a21 HPN |
8736 | @end ifset |
8737 | @ifset INTERNALS | |
03dda8e3 RK |
8738 | @node Tagging Insns |
8739 | @subsection Assigning Attribute Values to Insns | |
8740 | @cindex tagging insns | |
8741 | @cindex assigning attribute values to insns | |
8742 | ||
8743 | The value assigned to an attribute of an insn is primarily determined by | |
8744 | which pattern is matched by that insn (or which @code{define_peephole} | |
8745 | generated it). Every @code{define_insn} and @code{define_peephole} can | |
8746 | have an optional last argument to specify the values of attributes for | |
8747 | matching insns. The value of any attribute not specified in a particular | |
8748 | insn is set to the default value for that attribute, as specified in its | |
8749 | @code{define_attr}. Extensive use of default values for attributes | |
8750 | permits the specification of the values for only one or two attributes | |
8751 | in the definition of most insn patterns, as seen in the example in the | |
bd819a4a | 8752 | next section. |
03dda8e3 RK |
8753 | |
8754 | The optional last argument of @code{define_insn} and | |
8755 | @code{define_peephole} is a vector of expressions, each of which defines | |
8756 | the value for a single attribute. The most general way of assigning an | |
8757 | attribute's value is to use a @code{set} expression whose first operand is an | |
8758 | @code{attr} expression giving the name of the attribute being set. The | |
8759 | second operand of the @code{set} is an attribute expression | |
bd819a4a | 8760 | (@pxref{Expressions}) giving the value of the attribute. |
03dda8e3 RK |
8761 | |
8762 | When the attribute value depends on the @samp{alternative} attribute | |
8763 | (i.e., which is the applicable alternative in the constraint of the | |
8764 | insn), the @code{set_attr_alternative} expression can be used. It | |
8765 | allows the specification of a vector of attribute expressions, one for | |
8766 | each alternative. | |
8767 | ||
8768 | @findex set_attr | |
8769 | When the generality of arbitrary attribute expressions is not required, | |
8770 | the simpler @code{set_attr} expression can be used, which allows | |
8771 | specifying a string giving either a single attribute value or a list | |
8772 | of attribute values, one for each alternative. | |
8773 | ||
8774 | The form of each of the above specifications is shown below. In each case, | |
8775 | @var{name} is a string specifying the attribute to be set. | |
8776 | ||
8777 | @table @code | |
8778 | @item (set_attr @var{name} @var{value-string}) | |
8779 | @var{value-string} is either a string giving the desired attribute value, | |
8780 | or a string containing a comma-separated list giving the values for | |
8781 | succeeding alternatives. The number of elements must match the number | |
8782 | of alternatives in the constraint of the insn pattern. | |
8783 | ||
8784 | Note that it may be useful to specify @samp{*} for some alternative, in | |
8785 | which case the attribute will assume its default value for insns matching | |
8786 | that alternative. | |
8787 | ||
8788 | @findex set_attr_alternative | |
8789 | @item (set_attr_alternative @var{name} [@var{value1} @var{value2} @dots{}]) | |
8790 | Depending on the alternative of the insn, the value will be one of the | |
8791 | specified values. This is a shorthand for using a @code{cond} with | |
8792 | tests on the @samp{alternative} attribute. | |
8793 | ||
8794 | @findex attr | |
8795 | @item (set (attr @var{name}) @var{value}) | |
8796 | The first operand of this @code{set} must be the special RTL expression | |
8797 | @code{attr}, whose sole operand is a string giving the name of the | |
8798 | attribute being set. @var{value} is the value of the attribute. | |
8799 | @end table | |
8800 | ||
8801 | The following shows three different ways of representing the same | |
8802 | attribute value specification: | |
8803 | ||
8804 | @smallexample | |
8805 | (set_attr "type" "load,store,arith") | |
8806 | ||
8807 | (set_attr_alternative "type" | |
8808 | [(const_string "load") (const_string "store") | |
8809 | (const_string "arith")]) | |
8810 | ||
8811 | (set (attr "type") | |
8812 | (cond [(eq_attr "alternative" "1") (const_string "load") | |
8813 | (eq_attr "alternative" "2") (const_string "store")] | |
8814 | (const_string "arith"))) | |
8815 | @end smallexample | |
8816 | ||
8817 | @need 1000 | |
8818 | @findex define_asm_attributes | |
8819 | The @code{define_asm_attributes} expression provides a mechanism to | |
8820 | specify the attributes assigned to insns produced from an @code{asm} | |
8821 | statement. It has the form: | |
8822 | ||
8823 | @smallexample | |
8824 | (define_asm_attributes [@var{attr-sets}]) | |
8825 | @end smallexample | |
8826 | ||
8827 | @noindent | |
8828 | where @var{attr-sets} is specified the same as for both the | |
8829 | @code{define_insn} and the @code{define_peephole} expressions. | |
8830 | ||
8831 | These values will typically be the ``worst case'' attribute values. For | |
8832 | example, they might indicate that the condition code will be clobbered. | |
8833 | ||
8834 | A specification for a @code{length} attribute is handled specially. The | |
8835 | way to compute the length of an @code{asm} insn is to multiply the | |
8836 | length specified in the expression @code{define_asm_attributes} by the | |
8837 | number of machine instructions specified in the @code{asm} statement, | |
8838 | determined by counting the number of semicolons and newlines in the | |
8839 | string. Therefore, the value of the @code{length} attribute specified | |
8840 | in a @code{define_asm_attributes} should be the maximum possible length | |
8841 | of a single machine instruction. | |
8842 | ||
a5249a21 HPN |
8843 | @end ifset |
8844 | @ifset INTERNALS | |
03dda8e3 RK |
8845 | @node Attr Example |
8846 | @subsection Example of Attribute Specifications | |
8847 | @cindex attribute specifications example | |
8848 | @cindex attribute specifications | |
8849 | ||
8850 | The judicious use of defaulting is important in the efficient use of | |
8851 | insn attributes. Typically, insns are divided into @dfn{types} and an | |
8852 | attribute, customarily called @code{type}, is used to represent this | |
8853 | value. This attribute is normally used only to define the default value | |
8854 | for other attributes. An example will clarify this usage. | |
8855 | ||
8856 | Assume we have a RISC machine with a condition code and in which only | |
8857 | full-word operations are performed in registers. Let us assume that we | |
8858 | can divide all insns into loads, stores, (integer) arithmetic | |
8859 | operations, floating point operations, and branches. | |
8860 | ||
8861 | Here we will concern ourselves with determining the effect of an insn on | |
8862 | the condition code and will limit ourselves to the following possible | |
8863 | effects: The condition code can be set unpredictably (clobbered), not | |
8864 | be changed, be set to agree with the results of the operation, or only | |
8865 | changed if the item previously set into the condition code has been | |
8866 | modified. | |
8867 | ||
8868 | Here is part of a sample @file{md} file for such a machine: | |
8869 | ||
8870 | @smallexample | |
8871 | (define_attr "type" "load,store,arith,fp,branch" (const_string "arith")) | |
8872 | ||
8873 | (define_attr "cc" "clobber,unchanged,set,change0" | |
8874 | (cond [(eq_attr "type" "load") | |
8875 | (const_string "change0") | |
8876 | (eq_attr "type" "store,branch") | |
8877 | (const_string "unchanged") | |
8878 | (eq_attr "type" "arith") | |
8879 | (if_then_else (match_operand:SI 0 "" "") | |
8880 | (const_string "set") | |
8881 | (const_string "clobber"))] | |
8882 | (const_string "clobber"))) | |
8883 | ||
8884 | (define_insn "" | |
8885 | [(set (match_operand:SI 0 "general_operand" "=r,r,m") | |
8886 | (match_operand:SI 1 "general_operand" "r,m,r"))] | |
8887 | "" | |
8888 | "@@ | |
8889 | move %0,%1 | |
8890 | load %0,%1 | |
8891 | store %0,%1" | |
8892 | [(set_attr "type" "arith,load,store")]) | |
8893 | @end smallexample | |
8894 | ||
8895 | Note that we assume in the above example that arithmetic operations | |
8896 | performed on quantities smaller than a machine word clobber the condition | |
8897 | code since they will set the condition code to a value corresponding to the | |
8898 | full-word result. | |
8899 | ||
a5249a21 HPN |
8900 | @end ifset |
8901 | @ifset INTERNALS | |
03dda8e3 RK |
8902 | @node Insn Lengths |
8903 | @subsection Computing the Length of an Insn | |
8904 | @cindex insn lengths, computing | |
8905 | @cindex computing the length of an insn | |
8906 | ||
8907 | For many machines, multiple types of branch instructions are provided, each | |
8908 | for different length branch displacements. In most cases, the assembler | |
8909 | will choose the correct instruction to use. However, when the assembler | |
b49900cc | 8910 | cannot do so, GCC can when a special attribute, the @code{length} |
03dda8e3 RK |
8911 | attribute, is defined. This attribute must be defined to have numeric |
8912 | values by specifying a null string in its @code{define_attr}. | |
8913 | ||
b49900cc | 8914 | In the case of the @code{length} attribute, two additional forms of |
03dda8e3 RK |
8915 | arithmetic terms are allowed in test expressions: |
8916 | ||
8917 | @table @code | |
8918 | @cindex @code{match_dup} and attributes | |
8919 | @item (match_dup @var{n}) | |
8920 | This refers to the address of operand @var{n} of the current insn, which | |
8921 | must be a @code{label_ref}. | |
8922 | ||
8923 | @cindex @code{pc} and attributes | |
8924 | @item (pc) | |
0c94b59f EB |
8925 | For non-branch instructions and backward branch instructions, this refers |
8926 | to the address of the current insn. But for forward branch instructions, | |
8927 | this refers to the address of the next insn, because the length of the | |
03dda8e3 RK |
8928 | current insn is to be computed. |
8929 | @end table | |
8930 | ||
8931 | @cindex @code{addr_vec}, length of | |
8932 | @cindex @code{addr_diff_vec}, length of | |
8933 | For normal insns, the length will be determined by value of the | |
b49900cc | 8934 | @code{length} attribute. In the case of @code{addr_vec} and |
03dda8e3 RK |
8935 | @code{addr_diff_vec} insn patterns, the length is computed as |
8936 | the number of vectors multiplied by the size of each vector. | |
8937 | ||
8938 | Lengths are measured in addressable storage units (bytes). | |
8939 | ||
40da08e0 JL |
8940 | Note that it is possible to call functions via the @code{symbol_ref} |
8941 | mechanism to compute the length of an insn. However, if you use this | |
8942 | mechanism you must provide dummy clauses to express the maximum length | |
8943 | without using the function call. You can an example of this in the | |
8944 | @code{pa} machine description for the @code{call_symref} pattern. | |
8945 | ||
03dda8e3 RK |
8946 | The following macros can be used to refine the length computation: |
8947 | ||
8948 | @table @code | |
03dda8e3 RK |
8949 | @findex ADJUST_INSN_LENGTH |
8950 | @item ADJUST_INSN_LENGTH (@var{insn}, @var{length}) | |
8951 | If defined, modifies the length assigned to instruction @var{insn} as a | |
8952 | function of the context in which it is used. @var{length} is an lvalue | |
8953 | that contains the initially computed length of the insn and should be | |
a8aa4e0b | 8954 | updated with the correct length of the insn. |
03dda8e3 RK |
8955 | |
8956 | This macro will normally not be required. A case in which it is | |
161d7b59 | 8957 | required is the ROMP@. On this machine, the size of an @code{addr_vec} |
03dda8e3 RK |
8958 | insn must be increased by two to compensate for the fact that alignment |
8959 | may be required. | |
8960 | @end table | |
8961 | ||
8962 | @findex get_attr_length | |
8963 | The routine that returns @code{get_attr_length} (the value of the | |
8964 | @code{length} attribute) can be used by the output routine to | |
8965 | determine the form of the branch instruction to be written, as the | |
8966 | example below illustrates. | |
8967 | ||
8968 | As an example of the specification of variable-length branches, consider | |
8969 | the IBM 360. If we adopt the convention that a register will be set to | |
8970 | the starting address of a function, we can jump to labels within 4k of | |
8971 | the start using a four-byte instruction. Otherwise, we need a six-byte | |
8972 | sequence to load the address from memory and then branch to it. | |
8973 | ||
8974 | On such a machine, a pattern for a branch instruction might be specified | |
8975 | as follows: | |
8976 | ||
8977 | @smallexample | |
8978 | (define_insn "jump" | |
8979 | [(set (pc) | |
8980 | (label_ref (match_operand 0 "" "")))] | |
8981 | "" | |
03dda8e3 RK |
8982 | @{ |
8983 | return (get_attr_length (insn) == 4 | |
0f40f9f7 ZW |
8984 | ? "b %l0" : "l r15,=a(%l0); br r15"); |
8985 | @} | |
9c34dbbf ZW |
8986 | [(set (attr "length") |
8987 | (if_then_else (lt (match_dup 0) (const_int 4096)) | |
8988 | (const_int 4) | |
8989 | (const_int 6)))]) | |
03dda8e3 RK |
8990 | @end smallexample |
8991 | ||
a5249a21 HPN |
8992 | @end ifset |
8993 | @ifset INTERNALS | |
03dda8e3 RK |
8994 | @node Constant Attributes |
8995 | @subsection Constant Attributes | |
8996 | @cindex constant attributes | |
8997 | ||
8998 | A special form of @code{define_attr}, where the expression for the | |
8999 | default value is a @code{const} expression, indicates an attribute that | |
9000 | is constant for a given run of the compiler. Constant attributes may be | |
9001 | used to specify which variety of processor is used. For example, | |
9002 | ||
9003 | @smallexample | |
9004 | (define_attr "cpu" "m88100,m88110,m88000" | |
9005 | (const | |
9006 | (cond [(symbol_ref "TARGET_88100") (const_string "m88100") | |
9007 | (symbol_ref "TARGET_88110") (const_string "m88110")] | |
9008 | (const_string "m88000")))) | |
9009 | ||
9010 | (define_attr "memory" "fast,slow" | |
9011 | (const | |
9012 | (if_then_else (symbol_ref "TARGET_FAST_MEM") | |
9013 | (const_string "fast") | |
9014 | (const_string "slow")))) | |
9015 | @end smallexample | |
9016 | ||
9017 | The routine generated for constant attributes has no parameters as it | |
9018 | does not depend on any particular insn. RTL expressions used to define | |
9019 | the value of a constant attribute may use the @code{symbol_ref} form, | |
9020 | but may not use either the @code{match_operand} form or @code{eq_attr} | |
9021 | forms involving insn attributes. | |
9022 | ||
13b72c22 AK |
9023 | @end ifset |
9024 | @ifset INTERNALS | |
9025 | @node Mnemonic Attribute | |
9026 | @subsection Mnemonic Attribute | |
9027 | @cindex mnemonic attribute | |
9028 | ||
9029 | The @code{mnemonic} attribute is a string type attribute holding the | |
9030 | instruction mnemonic for an insn alternative. The attribute values | |
9031 | will automatically be generated by the machine description parser if | |
9032 | there is an attribute definition in the md file: | |
9033 | ||
9034 | @smallexample | |
9035 | (define_attr "mnemonic" "unknown" (const_string "unknown")) | |
9036 | @end smallexample | |
9037 | ||
9038 | The default value can be freely chosen as long as it does not collide | |
9039 | with any of the instruction mnemonics. This value will be used | |
9040 | whenever the machine description parser is not able to determine the | |
9041 | mnemonic string. This might be the case for output templates | |
9042 | containing more than a single instruction as in | |
9043 | @code{"mvcle\t%0,%1,0\;jo\t.-4"}. | |
9044 | ||
9045 | The @code{mnemonic} attribute set is not generated automatically if the | |
9046 | instruction string is generated via C code. | |
9047 | ||
9048 | An existing @code{mnemonic} attribute set in an insn definition will not | |
9049 | be overriden by the md file parser. That way it is possible to | |
9050 | manually set the instruction mnemonics for the cases where the md file | |
9051 | parser fails to determine it automatically. | |
9052 | ||
9053 | The @code{mnemonic} attribute is useful for dealing with instruction | |
9054 | specific properties in the pipeline description without defining | |
9055 | additional insn attributes. | |
9056 | ||
9057 | @smallexample | |
9058 | (define_attr "ooo_expanded" "" | |
9059 | (cond [(eq_attr "mnemonic" "dlr,dsgr,d,dsgf,stam,dsgfr,dlgr") | |
9060 | (const_int 1)] | |
9061 | (const_int 0))) | |
9062 | @end smallexample | |
9063 | ||
a5249a21 HPN |
9064 | @end ifset |
9065 | @ifset INTERNALS | |
03dda8e3 RK |
9066 | @node Delay Slots |
9067 | @subsection Delay Slot Scheduling | |
9068 | @cindex delay slots, defining | |
9069 | ||
9070 | The insn attribute mechanism can be used to specify the requirements for | |
9071 | delay slots, if any, on a target machine. An instruction is said to | |
9072 | require a @dfn{delay slot} if some instructions that are physically | |
9073 | after the instruction are executed as if they were located before it. | |
9074 | Classic examples are branch and call instructions, which often execute | |
9075 | the following instruction before the branch or call is performed. | |
9076 | ||
9077 | On some machines, conditional branch instructions can optionally | |
9078 | @dfn{annul} instructions in the delay slot. This means that the | |
9079 | instruction will not be executed for certain branch outcomes. Both | |
9080 | instructions that annul if the branch is true and instructions that | |
9081 | annul if the branch is false are supported. | |
9082 | ||
9083 | Delay slot scheduling differs from instruction scheduling in that | |
9084 | determining whether an instruction needs a delay slot is dependent only | |
9085 | on the type of instruction being generated, not on data flow between the | |
9086 | instructions. See the next section for a discussion of data-dependent | |
9087 | instruction scheduling. | |
9088 | ||
9089 | @findex define_delay | |
9090 | The requirement of an insn needing one or more delay slots is indicated | |
9091 | via the @code{define_delay} expression. It has the following form: | |
9092 | ||
9093 | @smallexample | |
9094 | (define_delay @var{test} | |
9095 | [@var{delay-1} @var{annul-true-1} @var{annul-false-1} | |
9096 | @var{delay-2} @var{annul-true-2} @var{annul-false-2} | |
9097 | @dots{}]) | |
9098 | @end smallexample | |
9099 | ||
9100 | @var{test} is an attribute test that indicates whether this | |
9101 | @code{define_delay} applies to a particular insn. If so, the number of | |
9102 | required delay slots is determined by the length of the vector specified | |
9103 | as the second argument. An insn placed in delay slot @var{n} must | |
9104 | satisfy attribute test @var{delay-n}. @var{annul-true-n} is an | |
9105 | attribute test that specifies which insns may be annulled if the branch | |
9106 | is true. Similarly, @var{annul-false-n} specifies which insns in the | |
9107 | delay slot may be annulled if the branch is false. If annulling is not | |
bd819a4a | 9108 | supported for that delay slot, @code{(nil)} should be coded. |
03dda8e3 RK |
9109 | |
9110 | For example, in the common case where branch and call insns require | |
9111 | a single delay slot, which may contain any insn other than a branch or | |
9112 | call, the following would be placed in the @file{md} file: | |
9113 | ||
9114 | @smallexample | |
9115 | (define_delay (eq_attr "type" "branch,call") | |
9116 | [(eq_attr "type" "!branch,call") (nil) (nil)]) | |
9117 | @end smallexample | |
9118 | ||
9119 | Multiple @code{define_delay} expressions may be specified. In this | |
9120 | case, each such expression specifies different delay slot requirements | |
9121 | and there must be no insn for which tests in two @code{define_delay} | |
9122 | expressions are both true. | |
9123 | ||
9124 | For example, if we have a machine that requires one delay slot for branches | |
9125 | but two for calls, no delay slot can contain a branch or call insn, | |
9126 | and any valid insn in the delay slot for the branch can be annulled if the | |
9127 | branch is true, we might represent this as follows: | |
9128 | ||
9129 | @smallexample | |
9130 | (define_delay (eq_attr "type" "branch") | |
9131 | [(eq_attr "type" "!branch,call") | |
9132 | (eq_attr "type" "!branch,call") | |
9133 | (nil)]) | |
9134 | ||
9135 | (define_delay (eq_attr "type" "call") | |
9136 | [(eq_attr "type" "!branch,call") (nil) (nil) | |
9137 | (eq_attr "type" "!branch,call") (nil) (nil)]) | |
9138 | @end smallexample | |
9139 | @c the above is *still* too long. --mew 4feb93 | |
9140 | ||
a5249a21 HPN |
9141 | @end ifset |
9142 | @ifset INTERNALS | |
fae15c93 VM |
9143 | @node Processor pipeline description |
9144 | @subsection Specifying processor pipeline description | |
9145 | @cindex processor pipeline description | |
9146 | @cindex processor functional units | |
9147 | @cindex instruction latency time | |
9148 | @cindex interlock delays | |
9149 | @cindex data dependence delays | |
9150 | @cindex reservation delays | |
9151 | @cindex pipeline hazard recognizer | |
9152 | @cindex automaton based pipeline description | |
9153 | @cindex regular expressions | |
9154 | @cindex deterministic finite state automaton | |
9155 | @cindex automaton based scheduler | |
9156 | @cindex RISC | |
9157 | @cindex VLIW | |
9158 | ||
ef261fee | 9159 | To achieve better performance, most modern processors |
fae15c93 VM |
9160 | (super-pipelined, superscalar @acronym{RISC}, and @acronym{VLIW} |
9161 | processors) have many @dfn{functional units} on which several | |
9162 | instructions can be executed simultaneously. An instruction starts | |
9163 | execution if its issue conditions are satisfied. If not, the | |
ef261fee | 9164 | instruction is stalled until its conditions are satisfied. Such |
fae15c93 | 9165 | @dfn{interlock (pipeline) delay} causes interruption of the fetching |
431ae0bf | 9166 | of successor instructions (or demands nop instructions, e.g.@: for some |
fae15c93 VM |
9167 | MIPS processors). |
9168 | ||
9169 | There are two major kinds of interlock delays in modern processors. | |
9170 | The first one is a data dependence delay determining @dfn{instruction | |
9171 | latency time}. The instruction execution is not started until all | |
9172 | source data have been evaluated by prior instructions (there are more | |
9173 | complex cases when the instruction execution starts even when the data | |
c0478a66 | 9174 | are not available but will be ready in given time after the |
fae15c93 VM |
9175 | instruction execution start). Taking the data dependence delays into |
9176 | account is simple. The data dependence (true, output, and | |
9177 | anti-dependence) delay between two instructions is given by a | |
9178 | constant. In most cases this approach is adequate. The second kind | |
9179 | of interlock delays is a reservation delay. The reservation delay | |
9180 | means that two instructions under execution will be in need of shared | |
431ae0bf | 9181 | processors resources, i.e.@: buses, internal registers, and/or |
fae15c93 VM |
9182 | functional units, which are reserved for some time. Taking this kind |
9183 | of delay into account is complex especially for modern @acronym{RISC} | |
9184 | processors. | |
9185 | ||
9186 | The task of exploiting more processor parallelism is solved by an | |
ef261fee | 9187 | instruction scheduler. For a better solution to this problem, the |
fae15c93 | 9188 | instruction scheduler has to have an adequate description of the |
fa0aee89 PB |
9189 | processor parallelism (or @dfn{pipeline description}). GCC |
9190 | machine descriptions describe processor parallelism and functional | |
9191 | unit reservations for groups of instructions with the aid of | |
9192 | @dfn{regular expressions}. | |
ef261fee R |
9193 | |
9194 | The GCC instruction scheduler uses a @dfn{pipeline hazard recognizer} to | |
fae15c93 | 9195 | figure out the possibility of the instruction issue by the processor |
ef261fee R |
9196 | on a given simulated processor cycle. The pipeline hazard recognizer is |
9197 | automatically generated from the processor pipeline description. The | |
fa0aee89 PB |
9198 | pipeline hazard recognizer generated from the machine description |
9199 | is based on a deterministic finite state automaton (@acronym{DFA}): | |
9200 | the instruction issue is possible if there is a transition from one | |
9201 | automaton state to another one. This algorithm is very fast, and | |
9202 | furthermore, its speed is not dependent on processor | |
9203 | complexity@footnote{However, the size of the automaton depends on | |
6ccde948 RW |
9204 | processor complexity. To limit this effect, machine descriptions |
9205 | can split orthogonal parts of the machine description among several | |
9206 | automata: but then, since each of these must be stepped independently, | |
9207 | this does cause a small decrease in the algorithm's performance.}. | |
fae15c93 | 9208 | |
fae15c93 | 9209 | @cindex automaton based pipeline description |
fa0aee89 PB |
9210 | The rest of this section describes the directives that constitute |
9211 | an automaton-based processor pipeline description. The order of | |
9212 | these constructions within the machine description file is not | |
9213 | important. | |
fae15c93 VM |
9214 | |
9215 | @findex define_automaton | |
9216 | @cindex pipeline hazard recognizer | |
9217 | The following optional construction describes names of automata | |
9218 | generated and used for the pipeline hazards recognition. Sometimes | |
9219 | the generated finite state automaton used by the pipeline hazard | |
ef261fee | 9220 | recognizer is large. If we use more than one automaton and bind functional |
daf2f129 | 9221 | units to the automata, the total size of the automata is usually |
fae15c93 VM |
9222 | less than the size of the single automaton. If there is no one such |
9223 | construction, only one finite state automaton is generated. | |
9224 | ||
9225 | @smallexample | |
9226 | (define_automaton @var{automata-names}) | |
9227 | @end smallexample | |
9228 | ||
9229 | @var{automata-names} is a string giving names of the automata. The | |
9230 | names are separated by commas. All the automata should have unique names. | |
c62347f0 | 9231 | The automaton name is used in the constructions @code{define_cpu_unit} and |
fae15c93 VM |
9232 | @code{define_query_cpu_unit}. |
9233 | ||
9234 | @findex define_cpu_unit | |
9235 | @cindex processor functional units | |
c62347f0 | 9236 | Each processor functional unit used in the description of instruction |
fae15c93 VM |
9237 | reservations should be described by the following construction. |
9238 | ||
9239 | @smallexample | |
9240 | (define_cpu_unit @var{unit-names} [@var{automaton-name}]) | |
9241 | @end smallexample | |
9242 | ||
9243 | @var{unit-names} is a string giving the names of the functional units | |
9244 | separated by commas. Don't use name @samp{nothing}, it is reserved | |
9245 | for other goals. | |
9246 | ||
ef261fee | 9247 | @var{automaton-name} is a string giving the name of the automaton with |
fae15c93 VM |
9248 | which the unit is bound. The automaton should be described in |
9249 | construction @code{define_automaton}. You should give | |
9250 | @dfn{automaton-name}, if there is a defined automaton. | |
9251 | ||
30028c85 VM |
9252 | The assignment of units to automata are constrained by the uses of the |
9253 | units in insn reservations. The most important constraint is: if a | |
9254 | unit reservation is present on a particular cycle of an alternative | |
9255 | for an insn reservation, then some unit from the same automaton must | |
9256 | be present on the same cycle for the other alternatives of the insn | |
9257 | reservation. The rest of the constraints are mentioned in the | |
9258 | description of the subsequent constructions. | |
9259 | ||
fae15c93 VM |
9260 | @findex define_query_cpu_unit |
9261 | @cindex querying function unit reservations | |
9262 | The following construction describes CPU functional units analogously | |
30028c85 VM |
9263 | to @code{define_cpu_unit}. The reservation of such units can be |
9264 | queried for an automaton state. The instruction scheduler never | |
9265 | queries reservation of functional units for given automaton state. So | |
9266 | as a rule, you don't need this construction. This construction could | |
431ae0bf | 9267 | be used for future code generation goals (e.g.@: to generate |
30028c85 | 9268 | @acronym{VLIW} insn templates). |
fae15c93 VM |
9269 | |
9270 | @smallexample | |
9271 | (define_query_cpu_unit @var{unit-names} [@var{automaton-name}]) | |
9272 | @end smallexample | |
9273 | ||
9274 | @var{unit-names} is a string giving names of the functional units | |
9275 | separated by commas. | |
9276 | ||
ef261fee | 9277 | @var{automaton-name} is a string giving the name of the automaton with |
fae15c93 VM |
9278 | which the unit is bound. |
9279 | ||
9280 | @findex define_insn_reservation | |
9281 | @cindex instruction latency time | |
9282 | @cindex regular expressions | |
9283 | @cindex data bypass | |
ef261fee | 9284 | The following construction is the major one to describe pipeline |
fae15c93 VM |
9285 | characteristics of an instruction. |
9286 | ||
9287 | @smallexample | |
9288 | (define_insn_reservation @var{insn-name} @var{default_latency} | |
9289 | @var{condition} @var{regexp}) | |
9290 | @end smallexample | |
9291 | ||
9292 | @var{default_latency} is a number giving latency time of the | |
9293 | instruction. There is an important difference between the old | |
9294 | description and the automaton based pipeline description. The latency | |
9295 | time is used for all dependencies when we use the old description. In | |
ef261fee R |
9296 | the automaton based pipeline description, the given latency time is only |
9297 | used for true dependencies. The cost of anti-dependencies is always | |
fae15c93 VM |
9298 | zero and the cost of output dependencies is the difference between |
9299 | latency times of the producing and consuming insns (if the difference | |
ef261fee R |
9300 | is negative, the cost is considered to be zero). You can always |
9301 | change the default costs for any description by using the target hook | |
fae15c93 VM |
9302 | @code{TARGET_SCHED_ADJUST_COST} (@pxref{Scheduling}). |
9303 | ||
cc6a602b | 9304 | @var{insn-name} is a string giving the internal name of the insn. The |
fae15c93 VM |
9305 | internal names are used in constructions @code{define_bypass} and in |
9306 | the automaton description file generated for debugging. The internal | |
ef261fee | 9307 | name has nothing in common with the names in @code{define_insn}. It is a |
fae15c93 VM |
9308 | good practice to use insn classes described in the processor manual. |
9309 | ||
9310 | @var{condition} defines what RTL insns are described by this | |
9311 | construction. You should remember that you will be in trouble if | |
9312 | @var{condition} for two or more different | |
9313 | @code{define_insn_reservation} constructions is TRUE for an insn. In | |
9314 | this case what reservation will be used for the insn is not defined. | |
9315 | Such cases are not checked during generation of the pipeline hazards | |
9316 | recognizer because in general recognizing that two conditions may have | |
9317 | the same value is quite difficult (especially if the conditions | |
9318 | contain @code{symbol_ref}). It is also not checked during the | |
9319 | pipeline hazard recognizer work because it would slow down the | |
9320 | recognizer considerably. | |
9321 | ||
ef261fee | 9322 | @var{regexp} is a string describing the reservation of the cpu's functional |
fae15c93 VM |
9323 | units by the instruction. The reservations are described by a regular |
9324 | expression according to the following syntax: | |
9325 | ||
9326 | @smallexample | |
9327 | regexp = regexp "," oneof | |
9328 | | oneof | |
9329 | ||
9330 | oneof = oneof "|" allof | |
9331 | | allof | |
9332 | ||
9333 | allof = allof "+" repeat | |
9334 | | repeat | |
daf2f129 | 9335 | |
fae15c93 VM |
9336 | repeat = element "*" number |
9337 | | element | |
9338 | ||
9339 | element = cpu_function_unit_name | |
9340 | | reservation_name | |
9341 | | result_name | |
9342 | | "nothing" | |
9343 | | "(" regexp ")" | |
9344 | @end smallexample | |
9345 | ||
9346 | @itemize @bullet | |
9347 | @item | |
9348 | @samp{,} is used for describing the start of the next cycle in | |
9349 | the reservation. | |
9350 | ||
9351 | @item | |
9352 | @samp{|} is used for describing a reservation described by the first | |
9353 | regular expression @strong{or} a reservation described by the second | |
9354 | regular expression @strong{or} etc. | |
9355 | ||
9356 | @item | |
9357 | @samp{+} is used for describing a reservation described by the first | |
9358 | regular expression @strong{and} a reservation described by the | |
9359 | second regular expression @strong{and} etc. | |
9360 | ||
9361 | @item | |
9362 | @samp{*} is used for convenience and simply means a sequence in which | |
9363 | the regular expression are repeated @var{number} times with cycle | |
9364 | advancing (see @samp{,}). | |
9365 | ||
9366 | @item | |
9367 | @samp{cpu_function_unit_name} denotes reservation of the named | |
9368 | functional unit. | |
9369 | ||
9370 | @item | |
9371 | @samp{reservation_name} --- see description of construction | |
9372 | @samp{define_reservation}. | |
9373 | ||
9374 | @item | |
9375 | @samp{nothing} denotes no unit reservations. | |
9376 | @end itemize | |
9377 | ||
9378 | @findex define_reservation | |
9379 | Sometimes unit reservations for different insns contain common parts. | |
9380 | In such case, you can simplify the pipeline description by describing | |
9381 | the common part by the following construction | |
9382 | ||
9383 | @smallexample | |
9384 | (define_reservation @var{reservation-name} @var{regexp}) | |
9385 | @end smallexample | |
9386 | ||
9387 | @var{reservation-name} is a string giving name of @var{regexp}. | |
9388 | Functional unit names and reservation names are in the same name | |
9389 | space. So the reservation names should be different from the | |
cc6a602b | 9390 | functional unit names and can not be the reserved name @samp{nothing}. |
fae15c93 VM |
9391 | |
9392 | @findex define_bypass | |
9393 | @cindex instruction latency time | |
9394 | @cindex data bypass | |
9395 | The following construction is used to describe exceptions in the | |
9396 | latency time for given instruction pair. This is so called bypasses. | |
9397 | ||
9398 | @smallexample | |
9399 | (define_bypass @var{number} @var{out_insn_names} @var{in_insn_names} | |
9400 | [@var{guard}]) | |
9401 | @end smallexample | |
9402 | ||
9403 | @var{number} defines when the result generated by the instructions | |
9404 | given in string @var{out_insn_names} will be ready for the | |
f9bf5a8e RS |
9405 | instructions given in string @var{in_insn_names}. Each of these |
9406 | strings is a comma-separated list of filename-style globs and | |
9407 | they refer to the names of @code{define_insn_reservation}s. | |
9408 | For example: | |
9409 | @smallexample | |
9410 | (define_bypass 1 "cpu1_load_*, cpu1_store_*" "cpu1_load_*") | |
9411 | @end smallexample | |
9412 | defines a bypass between instructions that start with | |
9413 | @samp{cpu1_load_} or @samp{cpu1_store_} and those that start with | |
9414 | @samp{cpu1_load_}. | |
fae15c93 | 9415 | |
ef261fee | 9416 | @var{guard} is an optional string giving the name of a C function which |
fae15c93 VM |
9417 | defines an additional guard for the bypass. The function will get the |
9418 | two insns as parameters. If the function returns zero the bypass will | |
9419 | be ignored for this case. The additional guard is necessary to | |
431ae0bf | 9420 | recognize complicated bypasses, e.g.@: when the consumer is only an address |
fae15c93 VM |
9421 | of insn @samp{store} (not a stored value). |
9422 | ||
20a07f44 VM |
9423 | If there are more one bypass with the same output and input insns, the |
9424 | chosen bypass is the first bypass with a guard in description whose | |
9425 | guard function returns nonzero. If there is no such bypass, then | |
9426 | bypass without the guard function is chosen. | |
9427 | ||
fae15c93 VM |
9428 | @findex exclusion_set |
9429 | @findex presence_set | |
30028c85 | 9430 | @findex final_presence_set |
fae15c93 | 9431 | @findex absence_set |
30028c85 | 9432 | @findex final_absence_set |
fae15c93 VM |
9433 | @cindex VLIW |
9434 | @cindex RISC | |
cc6a602b BE |
9435 | The following five constructions are usually used to describe |
9436 | @acronym{VLIW} processors, or more precisely, to describe a placement | |
9437 | of small instructions into @acronym{VLIW} instruction slots. They | |
9438 | can be used for @acronym{RISC} processors, too. | |
fae15c93 VM |
9439 | |
9440 | @smallexample | |
9441 | (exclusion_set @var{unit-names} @var{unit-names}) | |
30028c85 VM |
9442 | (presence_set @var{unit-names} @var{patterns}) |
9443 | (final_presence_set @var{unit-names} @var{patterns}) | |
9444 | (absence_set @var{unit-names} @var{patterns}) | |
9445 | (final_absence_set @var{unit-names} @var{patterns}) | |
fae15c93 VM |
9446 | @end smallexample |
9447 | ||
9448 | @var{unit-names} is a string giving names of functional units | |
9449 | separated by commas. | |
9450 | ||
30028c85 | 9451 | @var{patterns} is a string giving patterns of functional units |
0bdcd332 | 9452 | separated by comma. Currently pattern is one unit or units |
30028c85 VM |
9453 | separated by white-spaces. |
9454 | ||
fae15c93 VM |
9455 | The first construction (@samp{exclusion_set}) means that each |
9456 | functional unit in the first string can not be reserved simultaneously | |
9457 | with a unit whose name is in the second string and vice versa. For | |
9458 | example, the construction is useful for describing processors | |
431ae0bf | 9459 | (e.g.@: some SPARC processors) with a fully pipelined floating point |
fae15c93 VM |
9460 | functional unit which can execute simultaneously only single floating |
9461 | point insns or only double floating point insns. | |
9462 | ||
9463 | The second construction (@samp{presence_set}) means that each | |
9464 | functional unit in the first string can not be reserved unless at | |
30028c85 VM |
9465 | least one of pattern of units whose names are in the second string is |
9466 | reserved. This is an asymmetric relation. For example, it is useful | |
9467 | for description that @acronym{VLIW} @samp{slot1} is reserved after | |
9468 | @samp{slot0} reservation. We could describe it by the following | |
9469 | construction | |
9470 | ||
9471 | @smallexample | |
9472 | (presence_set "slot1" "slot0") | |
9473 | @end smallexample | |
9474 | ||
9475 | Or @samp{slot1} is reserved only after @samp{slot0} and unit @samp{b0} | |
9476 | reservation. In this case we could write | |
9477 | ||
9478 | @smallexample | |
9479 | (presence_set "slot1" "slot0 b0") | |
9480 | @end smallexample | |
9481 | ||
9482 | The third construction (@samp{final_presence_set}) is analogous to | |
9483 | @samp{presence_set}. The difference between them is when checking is | |
9484 | done. When an instruction is issued in given automaton state | |
9485 | reflecting all current and planned unit reservations, the automaton | |
9486 | state is changed. The first state is a source state, the second one | |
9487 | is a result state. Checking for @samp{presence_set} is done on the | |
9488 | source state reservation, checking for @samp{final_presence_set} is | |
9489 | done on the result reservation. This construction is useful to | |
9490 | describe a reservation which is actually two subsequent reservations. | |
9491 | For example, if we use | |
9492 | ||
9493 | @smallexample | |
9494 | (presence_set "slot1" "slot0") | |
9495 | @end smallexample | |
9496 | ||
9497 | the following insn will be never issued (because @samp{slot1} requires | |
9498 | @samp{slot0} which is absent in the source state). | |
9499 | ||
9500 | @smallexample | |
9501 | (define_reservation "insn_and_nop" "slot0 + slot1") | |
9502 | @end smallexample | |
9503 | ||
9504 | but it can be issued if we use analogous @samp{final_presence_set}. | |
9505 | ||
9506 | The forth construction (@samp{absence_set}) means that each functional | |
9507 | unit in the first string can be reserved only if each pattern of units | |
9508 | whose names are in the second string is not reserved. This is an | |
9509 | asymmetric relation (actually @samp{exclusion_set} is analogous to | |
ff2ce160 | 9510 | this one but it is symmetric). For example it might be useful in a |
a71b1c58 NC |
9511 | @acronym{VLIW} description to say that @samp{slot0} cannot be reserved |
9512 | after either @samp{slot1} or @samp{slot2} have been reserved. This | |
9513 | can be described as: | |
30028c85 VM |
9514 | |
9515 | @smallexample | |
a71b1c58 | 9516 | (absence_set "slot0" "slot1, slot2") |
30028c85 VM |
9517 | @end smallexample |
9518 | ||
9519 | Or @samp{slot2} can not be reserved if @samp{slot0} and unit @samp{b0} | |
9520 | are reserved or @samp{slot1} and unit @samp{b1} are reserved. In | |
9521 | this case we could write | |
9522 | ||
9523 | @smallexample | |
9524 | (absence_set "slot2" "slot0 b0, slot1 b1") | |
9525 | @end smallexample | |
fae15c93 | 9526 | |
ef261fee | 9527 | All functional units mentioned in a set should belong to the same |
fae15c93 VM |
9528 | automaton. |
9529 | ||
30028c85 VM |
9530 | The last construction (@samp{final_absence_set}) is analogous to |
9531 | @samp{absence_set} but checking is done on the result (state) | |
9532 | reservation. See comments for @samp{final_presence_set}. | |
9533 | ||
fae15c93 VM |
9534 | @findex automata_option |
9535 | @cindex deterministic finite state automaton | |
9536 | @cindex nondeterministic finite state automaton | |
9537 | @cindex finite state automaton minimization | |
9538 | You can control the generator of the pipeline hazard recognizer with | |
9539 | the following construction. | |
9540 | ||
9541 | @smallexample | |
9542 | (automata_option @var{options}) | |
9543 | @end smallexample | |
9544 | ||
9545 | @var{options} is a string giving options which affect the generated | |
9546 | code. Currently there are the following options: | |
9547 | ||
9548 | @itemize @bullet | |
9549 | @item | |
9550 | @dfn{no-minimization} makes no minimization of the automaton. This is | |
30028c85 VM |
9551 | only worth to do when we are debugging the description and need to |
9552 | look more accurately at reservations of states. | |
fae15c93 VM |
9553 | |
9554 | @item | |
df1133a6 BE |
9555 | @dfn{time} means printing time statistics about the generation of |
9556 | automata. | |
9557 | ||
9558 | @item | |
9559 | @dfn{stats} means printing statistics about the generated automata | |
9560 | such as the number of DFA states, NDFA states and arcs. | |
e3c8eb86 VM |
9561 | |
9562 | @item | |
9563 | @dfn{v} means a generation of the file describing the result automata. | |
9564 | The file has suffix @samp{.dfa} and can be used for the description | |
9565 | verification and debugging. | |
9566 | ||
9567 | @item | |
9568 | @dfn{w} means a generation of warning instead of error for | |
9569 | non-critical errors. | |
fae15c93 | 9570 | |
e12da141 BS |
9571 | @item |
9572 | @dfn{no-comb-vect} prevents the automaton generator from generating | |
9573 | two data structures and comparing them for space efficiency. Using | |
9574 | a comb vector to represent transitions may be better, but it can be | |
9575 | very expensive to construct. This option is useful if the build | |
9576 | process spends an unacceptably long time in genautomata. | |
9577 | ||
fae15c93 VM |
9578 | @item |
9579 | @dfn{ndfa} makes nondeterministic finite state automata. This affects | |
9580 | the treatment of operator @samp{|} in the regular expressions. The | |
9581 | usual treatment of the operator is to try the first alternative and, | |
9582 | if the reservation is not possible, the second alternative. The | |
9583 | nondeterministic treatment means trying all alternatives, some of them | |
96ddf8ef | 9584 | may be rejected by reservations in the subsequent insns. |
dfa849f3 | 9585 | |
1e6a9047 | 9586 | @item |
9c582551 | 9587 | @dfn{collapse-ndfa} modifies the behavior of the generator when |
1e6a9047 BS |
9588 | producing an automaton. An additional state transition to collapse a |
9589 | nondeterministic @acronym{NDFA} state to a deterministic @acronym{DFA} | |
9590 | state is generated. It can be triggered by passing @code{const0_rtx} to | |
9591 | state_transition. In such an automaton, cycle advance transitions are | |
9592 | available only for these collapsed states. This option is useful for | |
9593 | ports that want to use the @code{ndfa} option, but also want to use | |
9594 | @code{define_query_cpu_unit} to assign units to insns issued in a cycle. | |
9595 | ||
dfa849f3 VM |
9596 | @item |
9597 | @dfn{progress} means output of a progress bar showing how many states | |
9598 | were generated so far for automaton being processed. This is useful | |
9599 | during debugging a @acronym{DFA} description. If you see too many | |
9600 | generated states, you could interrupt the generator of the pipeline | |
9601 | hazard recognizer and try to figure out a reason for generation of the | |
9602 | huge automaton. | |
fae15c93 VM |
9603 | @end itemize |
9604 | ||
9605 | As an example, consider a superscalar @acronym{RISC} machine which can | |
9606 | issue three insns (two integer insns and one floating point insn) on | |
9607 | the cycle but can finish only two insns. To describe this, we define | |
9608 | the following functional units. | |
9609 | ||
9610 | @smallexample | |
9611 | (define_cpu_unit "i0_pipeline, i1_pipeline, f_pipeline") | |
ef261fee | 9612 | (define_cpu_unit "port0, port1") |
fae15c93 VM |
9613 | @end smallexample |
9614 | ||
9615 | All simple integer insns can be executed in any integer pipeline and | |
9616 | their result is ready in two cycles. The simple integer insns are | |
9617 | issued into the first pipeline unless it is reserved, otherwise they | |
9618 | are issued into the second pipeline. Integer division and | |
9619 | multiplication insns can be executed only in the second integer | |
9620 | pipeline and their results are ready correspondingly in 8 and 4 | |
431ae0bf | 9621 | cycles. The integer division is not pipelined, i.e.@: the subsequent |
fae15c93 VM |
9622 | integer division insn can not be issued until the current division |
9623 | insn finished. Floating point insns are fully pipelined and their | |
ef261fee R |
9624 | results are ready in 3 cycles. Where the result of a floating point |
9625 | insn is used by an integer insn, an additional delay of one cycle is | |
9626 | incurred. To describe all of this we could specify | |
fae15c93 VM |
9627 | |
9628 | @smallexample | |
9629 | (define_cpu_unit "div") | |
9630 | ||
68e4d4c5 | 9631 | (define_insn_reservation "simple" 2 (eq_attr "type" "int") |
ef261fee | 9632 | "(i0_pipeline | i1_pipeline), (port0 | port1)") |
fae15c93 | 9633 | |
68e4d4c5 | 9634 | (define_insn_reservation "mult" 4 (eq_attr "type" "mult") |
ef261fee | 9635 | "i1_pipeline, nothing*2, (port0 | port1)") |
fae15c93 | 9636 | |
68e4d4c5 | 9637 | (define_insn_reservation "div" 8 (eq_attr "type" "div") |
ef261fee | 9638 | "i1_pipeline, div*7, div + (port0 | port1)") |
fae15c93 | 9639 | |
68e4d4c5 | 9640 | (define_insn_reservation "float" 3 (eq_attr "type" "float") |
ef261fee | 9641 | "f_pipeline, nothing, (port0 | port1)) |
fae15c93 | 9642 | |
ef261fee | 9643 | (define_bypass 4 "float" "simple,mult,div") |
fae15c93 VM |
9644 | @end smallexample |
9645 | ||
9646 | To simplify the description we could describe the following reservation | |
9647 | ||
9648 | @smallexample | |
9649 | (define_reservation "finish" "port0|port1") | |
9650 | @end smallexample | |
9651 | ||
9652 | and use it in all @code{define_insn_reservation} as in the following | |
9653 | construction | |
9654 | ||
9655 | @smallexample | |
68e4d4c5 | 9656 | (define_insn_reservation "simple" 2 (eq_attr "type" "int") |
fae15c93 VM |
9657 | "(i0_pipeline | i1_pipeline), finish") |
9658 | @end smallexample | |
9659 | ||
9660 | ||
a5249a21 HPN |
9661 | @end ifset |
9662 | @ifset INTERNALS | |
3262c1f5 RH |
9663 | @node Conditional Execution |
9664 | @section Conditional Execution | |
9665 | @cindex conditional execution | |
9666 | @cindex predication | |
9667 | ||
9668 | A number of architectures provide for some form of conditional | |
9669 | execution, or predication. The hallmark of this feature is the | |
9670 | ability to nullify most of the instructions in the instruction set. | |
9671 | When the instruction set is large and not entirely symmetric, it | |
9672 | can be quite tedious to describe these forms directly in the | |
9673 | @file{.md} file. An alternative is the @code{define_cond_exec} template. | |
9674 | ||
9675 | @findex define_cond_exec | |
9676 | @smallexample | |
9677 | (define_cond_exec | |
9678 | [@var{predicate-pattern}] | |
9679 | "@var{condition}" | |
aadaf24e KT |
9680 | "@var{output-template}" |
9681 | "@var{optional-insn-attribues}") | |
3262c1f5 RH |
9682 | @end smallexample |
9683 | ||
9684 | @var{predicate-pattern} is the condition that must be true for the | |
9685 | insn to be executed at runtime and should match a relational operator. | |
9686 | One can use @code{match_operator} to match several relational operators | |
9687 | at once. Any @code{match_operand} operands must have no more than one | |
9688 | alternative. | |
9689 | ||
9690 | @var{condition} is a C expression that must be true for the generated | |
9691 | pattern to match. | |
9692 | ||
9693 | @findex current_insn_predicate | |
630d3d5a | 9694 | @var{output-template} is a string similar to the @code{define_insn} |
3262c1f5 RH |
9695 | output template (@pxref{Output Template}), except that the @samp{*} |
9696 | and @samp{@@} special cases do not apply. This is only useful if the | |
9697 | assembly text for the predicate is a simple prefix to the main insn. | |
9698 | In order to handle the general case, there is a global variable | |
9699 | @code{current_insn_predicate} that will contain the entire predicate | |
9700 | if the current insn is predicated, and will otherwise be @code{NULL}. | |
9701 | ||
aadaf24e KT |
9702 | @var{optional-insn-attributes} is an optional vector of attributes that gets |
9703 | appended to the insn attributes of the produced cond_exec rtx. It can | |
9704 | be used to add some distinguishing attribute to cond_exec rtxs produced | |
9705 | that way. An example usage would be to use this attribute in conjunction | |
9706 | with attributes on the main pattern to disable particular alternatives under | |
9707 | certain conditions. | |
9708 | ||
ebb48a4d JM |
9709 | When @code{define_cond_exec} is used, an implicit reference to |
9710 | the @code{predicable} instruction attribute is made. | |
0bddee8e BS |
9711 | @xref{Insn Attributes}. This attribute must be a boolean (i.e.@: have |
9712 | exactly two elements in its @var{list-of-values}), with the possible | |
9713 | values being @code{no} and @code{yes}. The default and all uses in | |
9714 | the insns must be a simple constant, not a complex expressions. It | |
9715 | may, however, depend on the alternative, by using a comma-separated | |
9716 | list of values. If that is the case, the port should also define an | |
9717 | @code{enabled} attribute (@pxref{Disable Insn Alternatives}), which | |
9718 | should also allow only @code{no} and @code{yes} as its values. | |
3262c1f5 | 9719 | |
ebb48a4d | 9720 | For each @code{define_insn} for which the @code{predicable} |
3262c1f5 RH |
9721 | attribute is true, a new @code{define_insn} pattern will be |
9722 | generated that matches a predicated version of the instruction. | |
9723 | For example, | |
9724 | ||
9725 | @smallexample | |
9726 | (define_insn "addsi" | |
9727 | [(set (match_operand:SI 0 "register_operand" "r") | |
9728 | (plus:SI (match_operand:SI 1 "register_operand" "r") | |
9729 | (match_operand:SI 2 "register_operand" "r")))] | |
9730 | "@var{test1}" | |
9731 | "add %2,%1,%0") | |
9732 | ||
9733 | (define_cond_exec | |
9734 | [(ne (match_operand:CC 0 "register_operand" "c") | |
9735 | (const_int 0))] | |
9736 | "@var{test2}" | |
9737 | "(%0)") | |
9738 | @end smallexample | |
9739 | ||
9740 | @noindent | |
9741 | generates a new pattern | |
9742 | ||
9743 | @smallexample | |
9744 | (define_insn "" | |
9745 | [(cond_exec | |
9746 | (ne (match_operand:CC 3 "register_operand" "c") (const_int 0)) | |
9747 | (set (match_operand:SI 0 "register_operand" "r") | |
9748 | (plus:SI (match_operand:SI 1 "register_operand" "r") | |
9749 | (match_operand:SI 2 "register_operand" "r"))))] | |
9750 | "(@var{test2}) && (@var{test1})" | |
9751 | "(%3) add %2,%1,%0") | |
9752 | @end smallexample | |
c25c12b8 | 9753 | |
a5249a21 | 9754 | @end ifset |
477c104e MK |
9755 | @ifset INTERNALS |
9756 | @node Define Subst | |
9757 | @section RTL Templates Transformations | |
9758 | @cindex define_subst | |
9759 | ||
9760 | For some hardware architectures there are common cases when the RTL | |
9761 | templates for the instructions can be derived from the other RTL | |
9762 | templates using simple transformations. E.g., @file{i386.md} contains | |
9763 | an RTL template for the ordinary @code{sub} instruction--- | |
9764 | @code{*subsi_1}, and for the @code{sub} instruction with subsequent | |
9765 | zero-extension---@code{*subsi_1_zext}. Such cases can be easily | |
9766 | implemented by a single meta-template capable of generating a modified | |
9767 | case based on the initial one: | |
9768 | ||
9769 | @findex define_subst | |
9770 | @smallexample | |
9771 | (define_subst "@var{name}" | |
9772 | [@var{input-template}] | |
9773 | "@var{condition}" | |
9774 | [@var{output-template}]) | |
9775 | @end smallexample | |
9776 | @var{input-template} is a pattern describing the source RTL template, | |
9777 | which will be transformed. | |
9778 | ||
9779 | @var{condition} is a C expression that is conjunct with the condition | |
9780 | from the input-template to generate a condition to be used in the | |
9781 | output-template. | |
9782 | ||
9783 | @var{output-template} is a pattern that will be used in the resulting | |
9784 | template. | |
9785 | ||
9786 | @code{define_subst} mechanism is tightly coupled with the notion of the | |
bdb6985c | 9787 | subst attribute (@pxref{Subst Iterators}). The use of |
477c104e MK |
9788 | @code{define_subst} is triggered by a reference to a subst attribute in |
9789 | the transforming RTL template. This reference initiates duplication of | |
9790 | the source RTL template and substitution of the attributes with their | |
9791 | values. The source RTL template is left unchanged, while the copy is | |
9792 | transformed by @code{define_subst}. This transformation can fail in the | |
9793 | case when the source RTL template is not matched against the | |
9794 | input-template of the @code{define_subst}. In such case the copy is | |
9795 | deleted. | |
9796 | ||
9797 | @code{define_subst} can be used only in @code{define_insn} and | |
9798 | @code{define_expand}, it cannot be used in other expressions (e.g. in | |
9799 | @code{define_insn_and_split}). | |
9800 | ||
9801 | @menu | |
9802 | * Define Subst Example:: Example of @code{define_subst} work. | |
9803 | * Define Subst Pattern Matching:: Process of template comparison. | |
9804 | * Define Subst Output Template:: Generation of output template. | |
9805 | @end menu | |
9806 | ||
9807 | @node Define Subst Example | |
9808 | @subsection @code{define_subst} Example | |
9809 | @cindex define_subst | |
9810 | ||
9811 | To illustrate how @code{define_subst} works, let us examine a simple | |
9812 | template transformation. | |
9813 | ||
9814 | Suppose there are two kinds of instructions: one that touches flags and | |
9815 | the other that does not. The instructions of the second type could be | |
9816 | generated with the following @code{define_subst}: | |
9817 | ||
9818 | @smallexample | |
9819 | (define_subst "add_clobber_subst" | |
9820 | [(set (match_operand:SI 0 "" "") | |
9821 | (match_operand:SI 1 "" ""))] | |
9822 | "" | |
9823 | [(set (match_dup 0) | |
9824 | (match_dup 1)) | |
9825 | (clobber (reg:CC FLAGS_REG))] | |
9826 | @end smallexample | |
9827 | ||
9828 | This @code{define_subst} can be applied to any RTL pattern containing | |
9829 | @code{set} of mode SI and generates a copy with clobber when it is | |
9830 | applied. | |
9831 | ||
9832 | Assume there is an RTL template for a @code{max} instruction to be used | |
9833 | in @code{define_subst} mentioned above: | |
9834 | ||
9835 | @smallexample | |
9836 | (define_insn "maxsi" | |
9837 | [(set (match_operand:SI 0 "register_operand" "=r") | |
9838 | (max:SI | |
9839 | (match_operand:SI 1 "register_operand" "r") | |
9840 | (match_operand:SI 2 "register_operand" "r")))] | |
9841 | "" | |
9842 | "max\t@{%2, %1, %0|%0, %1, %2@}" | |
9843 | [@dots{}]) | |
9844 | @end smallexample | |
9845 | ||
9846 | To mark the RTL template for @code{define_subst} application, | |
9847 | subst-attributes are used. They should be declared in advance: | |
9848 | ||
9849 | @smallexample | |
9850 | (define_subst_attr "add_clobber_name" "add_clobber_subst" "_noclobber" "_clobber") | |
9851 | @end smallexample | |
9852 | ||
9853 | Here @samp{add_clobber_name} is the attribute name, | |
9854 | @samp{add_clobber_subst} is the name of the corresponding | |
9855 | @code{define_subst}, the third argument (@samp{_noclobber}) is the | |
9856 | attribute value that would be substituted into the unchanged version of | |
9857 | the source RTL template, and the last argument (@samp{_clobber}) is the | |
9858 | value that would be substituted into the second, transformed, | |
9859 | version of the RTL template. | |
9860 | ||
9861 | Once the subst-attribute has been defined, it should be used in RTL | |
9862 | templates which need to be processed by the @code{define_subst}. So, | |
9863 | the original RTL template should be changed: | |
9864 | ||
9865 | @smallexample | |
9866 | (define_insn "maxsi<add_clobber_name>" | |
9867 | [(set (match_operand:SI 0 "register_operand" "=r") | |
9868 | (max:SI | |
9869 | (match_operand:SI 1 "register_operand" "r") | |
9870 | (match_operand:SI 2 "register_operand" "r")))] | |
9871 | "" | |
9872 | "max\t@{%2, %1, %0|%0, %1, %2@}" | |
9873 | [@dots{}]) | |
9874 | @end smallexample | |
9875 | ||
9876 | The result of the @code{define_subst} usage would look like the following: | |
9877 | ||
9878 | @smallexample | |
9879 | (define_insn "maxsi_noclobber" | |
9880 | [(set (match_operand:SI 0 "register_operand" "=r") | |
9881 | (max:SI | |
9882 | (match_operand:SI 1 "register_operand" "r") | |
9883 | (match_operand:SI 2 "register_operand" "r")))] | |
9884 | "" | |
9885 | "max\t@{%2, %1, %0|%0, %1, %2@}" | |
9886 | [@dots{}]) | |
9887 | (define_insn "maxsi_clobber" | |
9888 | [(set (match_operand:SI 0 "register_operand" "=r") | |
9889 | (max:SI | |
9890 | (match_operand:SI 1 "register_operand" "r") | |
9891 | (match_operand:SI 2 "register_operand" "r"))) | |
9892 | (clobber (reg:CC FLAGS_REG))] | |
9893 | "" | |
9894 | "max\t@{%2, %1, %0|%0, %1, %2@}" | |
9895 | [@dots{}]) | |
9896 | @end smallexample | |
9897 | ||
9898 | @node Define Subst Pattern Matching | |
9899 | @subsection Pattern Matching in @code{define_subst} | |
9900 | @cindex define_subst | |
9901 | ||
9902 | All expressions, allowed in @code{define_insn} or @code{define_expand}, | |
9903 | are allowed in the input-template of @code{define_subst}, except | |
9904 | @code{match_par_dup}, @code{match_scratch}, @code{match_parallel}. The | |
9905 | meanings of expressions in the input-template were changed: | |
9906 | ||
9907 | @code{match_operand} matches any expression (possibly, a subtree in | |
9908 | RTL-template), if modes of the @code{match_operand} and this expression | |
9909 | are the same, or mode of the @code{match_operand} is @code{VOIDmode}, or | |
9910 | this expression is @code{match_dup}, @code{match_op_dup}. If the | |
9911 | expression is @code{match_operand} too, and predicate of | |
9912 | @code{match_operand} from the input pattern is not empty, then the | |
9913 | predicates are compared. That can be used for more accurate filtering | |
9914 | of accepted RTL-templates. | |
9915 | ||
9916 | @code{match_operator} matches common operators (like @code{plus}, | |
9917 | @code{minus}), @code{unspec}, @code{unspec_volatile} operators and | |
9918 | @code{match_operator}s from the original pattern if the modes match and | |
9919 | @code{match_operator} from the input pattern has the same number of | |
9920 | operands as the operator from the original pattern. | |
9921 | ||
9922 | @node Define Subst Output Template | |
9923 | @subsection Generation of output template in @code{define_subst} | |
9924 | @cindex define_subst | |
9925 | ||
9926 | If all necessary checks for @code{define_subst} application pass, a new | |
9927 | RTL-pattern, based on the output-template, is created to replace the old | |
9928 | template. Like in input-patterns, meanings of some RTL expressions are | |
9929 | changed when they are used in output-patterns of a @code{define_subst}. | |
9930 | Thus, @code{match_dup} is used for copying the whole expression from the | |
9931 | original pattern, which matched corresponding @code{match_operand} from | |
9932 | the input pattern. | |
9933 | ||
9934 | @code{match_dup N} is used in the output template to be replaced with | |
9935 | the expression from the original pattern, which matched | |
9936 | @code{match_operand N} from the input pattern. As a consequence, | |
9937 | @code{match_dup} cannot be used to point to @code{match_operand}s from | |
9938 | the output pattern, it should always refer to a @code{match_operand} | |
9939 | from the input pattern. | |
9940 | ||
9941 | In the output template one can refer to the expressions from the | |
9942 | original pattern and create new ones. For instance, some operands could | |
9943 | be added by means of standard @code{match_operand}. | |
9944 | ||
9945 | After replacing @code{match_dup} with some RTL-subtree from the original | |
9946 | pattern, it could happen that several @code{match_operand}s in the | |
9947 | output pattern have the same indexes. It is unknown, how many and what | |
9948 | indexes would be used in the expression which would replace | |
9949 | @code{match_dup}, so such conflicts in indexes are inevitable. To | |
9950 | overcome this issue, @code{match_operands} and @code{match_operators}, | |
9951 | which were introduced into the output pattern, are renumerated when all | |
9952 | @code{match_dup}s are replaced. | |
9953 | ||
9954 | Number of alternatives in @code{match_operand}s introduced into the | |
9955 | output template @code{M} could differ from the number of alternatives in | |
9956 | the original pattern @code{N}, so in the resultant pattern there would | |
9957 | be @code{N*M} alternatives. Thus, constraints from the original pattern | |
9958 | would be duplicated @code{N} times, constraints from the output pattern | |
9959 | would be duplicated @code{M} times, producing all possible combinations. | |
9960 | @end ifset | |
9961 | ||
a5249a21 | 9962 | @ifset INTERNALS |
c25c12b8 R |
9963 | @node Constant Definitions |
9964 | @section Constant Definitions | |
9965 | @cindex constant definitions | |
9966 | @findex define_constants | |
9967 | ||
9968 | Using literal constants inside instruction patterns reduces legibility and | |
9969 | can be a maintenance problem. | |
9970 | ||
9971 | To overcome this problem, you may use the @code{define_constants} | |
9972 | expression. It contains a vector of name-value pairs. From that | |
9973 | point on, wherever any of the names appears in the MD file, it is as | |
9974 | if the corresponding value had been written instead. You may use | |
9975 | @code{define_constants} multiple times; each appearance adds more | |
9976 | constants to the table. It is an error to redefine a constant with | |
9977 | a different value. | |
9978 | ||
9979 | To come back to the a29k load multiple example, instead of | |
9980 | ||
9981 | @smallexample | |
9982 | (define_insn "" | |
9983 | [(match_parallel 0 "load_multiple_operation" | |
9984 | [(set (match_operand:SI 1 "gpc_reg_operand" "=r") | |
9985 | (match_operand:SI 2 "memory_operand" "m")) | |
9986 | (use (reg:SI 179)) | |
9987 | (clobber (reg:SI 179))])] | |
9988 | "" | |
9989 | "loadm 0,0,%1,%2") | |
9990 | @end smallexample | |
9991 | ||
9992 | You could write: | |
9993 | ||
9994 | @smallexample | |
9995 | (define_constants [ | |
9996 | (R_BP 177) | |
9997 | (R_FC 178) | |
9998 | (R_CR 179) | |
9999 | (R_Q 180) | |
10000 | ]) | |
10001 | ||
10002 | (define_insn "" | |
10003 | [(match_parallel 0 "load_multiple_operation" | |
10004 | [(set (match_operand:SI 1 "gpc_reg_operand" "=r") | |
10005 | (match_operand:SI 2 "memory_operand" "m")) | |
10006 | (use (reg:SI R_CR)) | |
10007 | (clobber (reg:SI R_CR))])] | |
10008 | "" | |
10009 | "loadm 0,0,%1,%2") | |
10010 | @end smallexample | |
10011 | ||
10012 | The constants that are defined with a define_constant are also output | |
10013 | in the insn-codes.h header file as #defines. | |
24609606 RS |
10014 | |
10015 | @cindex enumerations | |
10016 | @findex define_c_enum | |
10017 | You can also use the machine description file to define enumerations. | |
10018 | Like the constants defined by @code{define_constant}, these enumerations | |
10019 | are visible to both the machine description file and the main C code. | |
10020 | ||
10021 | The syntax is as follows: | |
10022 | ||
10023 | @smallexample | |
10024 | (define_c_enum "@var{name}" [ | |
10025 | @var{value0} | |
10026 | @var{value1} | |
10027 | @dots{} | |
10028 | @var{valuen} | |
10029 | ]) | |
10030 | @end smallexample | |
10031 | ||
10032 | This definition causes the equivalent of the following C code to appear | |
10033 | in @file{insn-constants.h}: | |
10034 | ||
10035 | @smallexample | |
10036 | enum @var{name} @{ | |
10037 | @var{value0} = 0, | |
10038 | @var{value1} = 1, | |
10039 | @dots{} | |
10040 | @var{valuen} = @var{n} | |
10041 | @}; | |
10042 | #define NUM_@var{cname}_VALUES (@var{n} + 1) | |
10043 | @end smallexample | |
10044 | ||
10045 | where @var{cname} is the capitalized form of @var{name}. | |
10046 | It also makes each @var{valuei} available in the machine description | |
10047 | file, just as if it had been declared with: | |
10048 | ||
10049 | @smallexample | |
10050 | (define_constants [(@var{valuei} @var{i})]) | |
10051 | @end smallexample | |
10052 | ||
10053 | Each @var{valuei} is usually an upper-case identifier and usually | |
10054 | begins with @var{cname}. | |
10055 | ||
10056 | You can split the enumeration definition into as many statements as | |
10057 | you like. The above example is directly equivalent to: | |
10058 | ||
10059 | @smallexample | |
10060 | (define_c_enum "@var{name}" [@var{value0}]) | |
10061 | (define_c_enum "@var{name}" [@var{value1}]) | |
10062 | @dots{} | |
10063 | (define_c_enum "@var{name}" [@var{valuen}]) | |
10064 | @end smallexample | |
10065 | ||
10066 | Splitting the enumeration helps to improve the modularity of each | |
10067 | individual @code{.md} file. For example, if a port defines its | |
10068 | synchronization instructions in a separate @file{sync.md} file, | |
10069 | it is convenient to define all synchronization-specific enumeration | |
10070 | values in @file{sync.md} rather than in the main @file{.md} file. | |
10071 | ||
0fe60a1b RS |
10072 | Some enumeration names have special significance to GCC: |
10073 | ||
10074 | @table @code | |
10075 | @item unspecv | |
10076 | @findex unspec_volatile | |
10077 | If an enumeration called @code{unspecv} is defined, GCC will use it | |
10078 | when printing out @code{unspec_volatile} expressions. For example: | |
10079 | ||
10080 | @smallexample | |
10081 | (define_c_enum "unspecv" [ | |
10082 | UNSPECV_BLOCKAGE | |
10083 | ]) | |
10084 | @end smallexample | |
10085 | ||
10086 | causes GCC to print @samp{(unspec_volatile @dots{} 0)} as: | |
10087 | ||
10088 | @smallexample | |
10089 | (unspec_volatile ... UNSPECV_BLOCKAGE) | |
10090 | @end smallexample | |
10091 | ||
10092 | @item unspec | |
10093 | @findex unspec | |
10094 | If an enumeration called @code{unspec} is defined, GCC will use | |
10095 | it when printing out @code{unspec} expressions. GCC will also use | |
10096 | it when printing out @code{unspec_volatile} expressions unless an | |
10097 | @code{unspecv} enumeration is also defined. You can therefore | |
10098 | decide whether to keep separate enumerations for volatile and | |
10099 | non-volatile expressions or whether to use the same enumeration | |
10100 | for both. | |
10101 | @end table | |
10102 | ||
24609606 | 10103 | @findex define_enum |
8f4fe86c | 10104 | @anchor{define_enum} |
24609606 RS |
10105 | Another way of defining an enumeration is to use @code{define_enum}: |
10106 | ||
10107 | @smallexample | |
10108 | (define_enum "@var{name}" [ | |
10109 | @var{value0} | |
10110 | @var{value1} | |
10111 | @dots{} | |
10112 | @var{valuen} | |
10113 | ]) | |
10114 | @end smallexample | |
10115 | ||
10116 | This directive implies: | |
10117 | ||
10118 | @smallexample | |
10119 | (define_c_enum "@var{name}" [ | |
10120 | @var{cname}_@var{cvalue0} | |
10121 | @var{cname}_@var{cvalue1} | |
10122 | @dots{} | |
10123 | @var{cname}_@var{cvaluen} | |
10124 | ]) | |
10125 | @end smallexample | |
10126 | ||
8f4fe86c | 10127 | @findex define_enum_attr |
24609606 | 10128 | where @var{cvaluei} is the capitalized form of @var{valuei}. |
8f4fe86c RS |
10129 | However, unlike @code{define_c_enum}, the enumerations defined |
10130 | by @code{define_enum} can be used in attribute specifications | |
10131 | (@pxref{define_enum_attr}). | |
b11cc610 | 10132 | @end ifset |
032e8348 | 10133 | @ifset INTERNALS |
3abcb3a7 HPN |
10134 | @node Iterators |
10135 | @section Iterators | |
10136 | @cindex iterators in @file{.md} files | |
032e8348 RS |
10137 | |
10138 | Ports often need to define similar patterns for more than one machine | |
3abcb3a7 | 10139 | mode or for more than one rtx code. GCC provides some simple iterator |
032e8348 RS |
10140 | facilities to make this process easier. |
10141 | ||
10142 | @menu | |
3abcb3a7 HPN |
10143 | * Mode Iterators:: Generating variations of patterns for different modes. |
10144 | * Code Iterators:: Doing the same for codes. | |
57a4717b | 10145 | * Int Iterators:: Doing the same for integers. |
477c104e | 10146 | * Subst Iterators:: Generating variations of patterns for define_subst. |
032e8348 RS |
10147 | @end menu |
10148 | ||
3abcb3a7 HPN |
10149 | @node Mode Iterators |
10150 | @subsection Mode Iterators | |
10151 | @cindex mode iterators in @file{.md} files | |
032e8348 RS |
10152 | |
10153 | Ports often need to define similar patterns for two or more different modes. | |
10154 | For example: | |
10155 | ||
10156 | @itemize @bullet | |
10157 | @item | |
10158 | If a processor has hardware support for both single and double | |
10159 | floating-point arithmetic, the @code{SFmode} patterns tend to be | |
10160 | very similar to the @code{DFmode} ones. | |
10161 | ||
10162 | @item | |
10163 | If a port uses @code{SImode} pointers in one configuration and | |
10164 | @code{DImode} pointers in another, it will usually have very similar | |
10165 | @code{SImode} and @code{DImode} patterns for manipulating pointers. | |
10166 | @end itemize | |
10167 | ||
3abcb3a7 | 10168 | Mode iterators allow several patterns to be instantiated from one |
032e8348 RS |
10169 | @file{.md} file template. They can be used with any type of |
10170 | rtx-based construct, such as a @code{define_insn}, | |
10171 | @code{define_split}, or @code{define_peephole2}. | |
10172 | ||
10173 | @menu | |
3abcb3a7 | 10174 | * Defining Mode Iterators:: Defining a new mode iterator. |
6ccde948 RW |
10175 | * Substitutions:: Combining mode iterators with substitutions |
10176 | * Examples:: Examples | |
032e8348 RS |
10177 | @end menu |
10178 | ||
3abcb3a7 HPN |
10179 | @node Defining Mode Iterators |
10180 | @subsubsection Defining Mode Iterators | |
10181 | @findex define_mode_iterator | |
032e8348 | 10182 | |
3abcb3a7 | 10183 | The syntax for defining a mode iterator is: |
032e8348 RS |
10184 | |
10185 | @smallexample | |
923158be | 10186 | (define_mode_iterator @var{name} [(@var{mode1} "@var{cond1}") @dots{} (@var{moden} "@var{condn}")]) |
032e8348 RS |
10187 | @end smallexample |
10188 | ||
10189 | This allows subsequent @file{.md} file constructs to use the mode suffix | |
10190 | @code{:@var{name}}. Every construct that does so will be expanded | |
10191 | @var{n} times, once with every use of @code{:@var{name}} replaced by | |
10192 | @code{:@var{mode1}}, once with every use replaced by @code{:@var{mode2}}, | |
10193 | and so on. In the expansion for a particular @var{modei}, every | |
10194 | C condition will also require that @var{condi} be true. | |
10195 | ||
10196 | For example: | |
10197 | ||
10198 | @smallexample | |
3abcb3a7 | 10199 | (define_mode_iterator P [(SI "Pmode == SImode") (DI "Pmode == DImode")]) |
032e8348 RS |
10200 | @end smallexample |
10201 | ||
10202 | defines a new mode suffix @code{:P}. Every construct that uses | |
10203 | @code{:P} will be expanded twice, once with every @code{:P} replaced | |
10204 | by @code{:SI} and once with every @code{:P} replaced by @code{:DI}. | |
10205 | The @code{:SI} version will only apply if @code{Pmode == SImode} and | |
10206 | the @code{:DI} version will only apply if @code{Pmode == DImode}. | |
10207 | ||
10208 | As with other @file{.md} conditions, an empty string is treated | |
10209 | as ``always true''. @code{(@var{mode} "")} can also be abbreviated | |
10210 | to @code{@var{mode}}. For example: | |
10211 | ||
10212 | @smallexample | |
3abcb3a7 | 10213 | (define_mode_iterator GPR [SI (DI "TARGET_64BIT")]) |
032e8348 RS |
10214 | @end smallexample |
10215 | ||
10216 | means that the @code{:DI} expansion only applies if @code{TARGET_64BIT} | |
10217 | but that the @code{:SI} expansion has no such constraint. | |
10218 | ||
3abcb3a7 HPN |
10219 | Iterators are applied in the order they are defined. This can be |
10220 | significant if two iterators are used in a construct that requires | |
f30990b2 | 10221 | substitutions. @xref{Substitutions}. |
032e8348 | 10222 | |
f30990b2 | 10223 | @node Substitutions |
3abcb3a7 | 10224 | @subsubsection Substitution in Mode Iterators |
032e8348 RS |
10225 | @findex define_mode_attr |
10226 | ||
3abcb3a7 | 10227 | If an @file{.md} file construct uses mode iterators, each version of the |
f30990b2 ILT |
10228 | construct will often need slightly different strings or modes. For |
10229 | example: | |
032e8348 RS |
10230 | |
10231 | @itemize @bullet | |
10232 | @item | |
10233 | When a @code{define_expand} defines several @code{add@var{m}3} patterns | |
10234 | (@pxref{Standard Names}), each expander will need to use the | |
10235 | appropriate mode name for @var{m}. | |
10236 | ||
10237 | @item | |
10238 | When a @code{define_insn} defines several instruction patterns, | |
10239 | each instruction will often use a different assembler mnemonic. | |
f30990b2 ILT |
10240 | |
10241 | @item | |
10242 | When a @code{define_insn} requires operands with different modes, | |
3abcb3a7 | 10243 | using an iterator for one of the operand modes usually requires a specific |
f30990b2 | 10244 | mode for the other operand(s). |
032e8348 RS |
10245 | @end itemize |
10246 | ||
10247 | GCC supports such variations through a system of ``mode attributes''. | |
10248 | There are two standard attributes: @code{mode}, which is the name of | |
10249 | the mode in lower case, and @code{MODE}, which is the same thing in | |
10250 | upper case. You can define other attributes using: | |
10251 | ||
10252 | @smallexample | |
923158be | 10253 | (define_mode_attr @var{name} [(@var{mode1} "@var{value1}") @dots{} (@var{moden} "@var{valuen}")]) |
032e8348 RS |
10254 | @end smallexample |
10255 | ||
10256 | where @var{name} is the name of the attribute and @var{valuei} | |
10257 | is the value associated with @var{modei}. | |
10258 | ||
3abcb3a7 | 10259 | When GCC replaces some @var{:iterator} with @var{:mode}, it will scan |
f30990b2 | 10260 | each string and mode in the pattern for sequences of the form |
3abcb3a7 | 10261 | @code{<@var{iterator}:@var{attr}>}, where @var{attr} is the name of a |
f30990b2 | 10262 | mode attribute. If the attribute is defined for @var{mode}, the whole |
923158be | 10263 | @code{<@dots{}>} sequence will be replaced by the appropriate attribute |
f30990b2 | 10264 | value. |
032e8348 RS |
10265 | |
10266 | For example, suppose an @file{.md} file has: | |
10267 | ||
10268 | @smallexample | |
3abcb3a7 | 10269 | (define_mode_iterator P [(SI "Pmode == SImode") (DI "Pmode == DImode")]) |
032e8348 RS |
10270 | (define_mode_attr load [(SI "lw") (DI "ld")]) |
10271 | @end smallexample | |
10272 | ||
10273 | If one of the patterns that uses @code{:P} contains the string | |
10274 | @code{"<P:load>\t%0,%1"}, the @code{SI} version of that pattern | |
10275 | will use @code{"lw\t%0,%1"} and the @code{DI} version will use | |
10276 | @code{"ld\t%0,%1"}. | |
10277 | ||
f30990b2 ILT |
10278 | Here is an example of using an attribute for a mode: |
10279 | ||
10280 | @smallexample | |
3abcb3a7 | 10281 | (define_mode_iterator LONG [SI DI]) |
f30990b2 | 10282 | (define_mode_attr SHORT [(SI "HI") (DI "SI")]) |
923158be RW |
10283 | (define_insn @dots{} |
10284 | (sign_extend:LONG (match_operand:<LONG:SHORT> @dots{})) @dots{}) | |
f30990b2 ILT |
10285 | @end smallexample |
10286 | ||
3abcb3a7 HPN |
10287 | The @code{@var{iterator}:} prefix may be omitted, in which case the |
10288 | substitution will be attempted for every iterator expansion. | |
032e8348 RS |
10289 | |
10290 | @node Examples | |
3abcb3a7 | 10291 | @subsubsection Mode Iterator Examples |
032e8348 RS |
10292 | |
10293 | Here is an example from the MIPS port. It defines the following | |
10294 | modes and attributes (among others): | |
10295 | ||
10296 | @smallexample | |
3abcb3a7 | 10297 | (define_mode_iterator GPR [SI (DI "TARGET_64BIT")]) |
032e8348 RS |
10298 | (define_mode_attr d [(SI "") (DI "d")]) |
10299 | @end smallexample | |
10300 | ||
10301 | and uses the following template to define both @code{subsi3} | |
10302 | and @code{subdi3}: | |
10303 | ||
10304 | @smallexample | |
10305 | (define_insn "sub<mode>3" | |
10306 | [(set (match_operand:GPR 0 "register_operand" "=d") | |
10307 | (minus:GPR (match_operand:GPR 1 "register_operand" "d") | |
10308 | (match_operand:GPR 2 "register_operand" "d")))] | |
10309 | "" | |
10310 | "<d>subu\t%0,%1,%2" | |
10311 | [(set_attr "type" "arith") | |
10312 | (set_attr "mode" "<MODE>")]) | |
10313 | @end smallexample | |
10314 | ||
10315 | This is exactly equivalent to: | |
10316 | ||
10317 | @smallexample | |
10318 | (define_insn "subsi3" | |
10319 | [(set (match_operand:SI 0 "register_operand" "=d") | |
10320 | (minus:SI (match_operand:SI 1 "register_operand" "d") | |
10321 | (match_operand:SI 2 "register_operand" "d")))] | |
10322 | "" | |
10323 | "subu\t%0,%1,%2" | |
10324 | [(set_attr "type" "arith") | |
10325 | (set_attr "mode" "SI")]) | |
10326 | ||
10327 | (define_insn "subdi3" | |
10328 | [(set (match_operand:DI 0 "register_operand" "=d") | |
10329 | (minus:DI (match_operand:DI 1 "register_operand" "d") | |
10330 | (match_operand:DI 2 "register_operand" "d")))] | |
10331 | "" | |
10332 | "dsubu\t%0,%1,%2" | |
10333 | [(set_attr "type" "arith") | |
10334 | (set_attr "mode" "DI")]) | |
10335 | @end smallexample | |
10336 | ||
3abcb3a7 HPN |
10337 | @node Code Iterators |
10338 | @subsection Code Iterators | |
10339 | @cindex code iterators in @file{.md} files | |
10340 | @findex define_code_iterator | |
032e8348 RS |
10341 | @findex define_code_attr |
10342 | ||
3abcb3a7 | 10343 | Code iterators operate in a similar way to mode iterators. @xref{Mode Iterators}. |
032e8348 RS |
10344 | |
10345 | The construct: | |
10346 | ||
10347 | @smallexample | |
923158be | 10348 | (define_code_iterator @var{name} [(@var{code1} "@var{cond1}") @dots{} (@var{coden} "@var{condn}")]) |
032e8348 RS |
10349 | @end smallexample |
10350 | ||
10351 | defines a pseudo rtx code @var{name} that can be instantiated as | |
10352 | @var{codei} if condition @var{condi} is true. Each @var{codei} | |
10353 | must have the same rtx format. @xref{RTL Classes}. | |
10354 | ||
3abcb3a7 | 10355 | As with mode iterators, each pattern that uses @var{name} will be |
032e8348 RS |
10356 | expanded @var{n} times, once with all uses of @var{name} replaced by |
10357 | @var{code1}, once with all uses replaced by @var{code2}, and so on. | |
3abcb3a7 | 10358 | @xref{Defining Mode Iterators}. |
032e8348 RS |
10359 | |
10360 | It is possible to define attributes for codes as well as for modes. | |
10361 | There are two standard code attributes: @code{code}, the name of the | |
10362 | code in lower case, and @code{CODE}, the name of the code in upper case. | |
10363 | Other attributes are defined using: | |
10364 | ||
10365 | @smallexample | |
923158be | 10366 | (define_code_attr @var{name} [(@var{code1} "@var{value1}") @dots{} (@var{coden} "@var{valuen}")]) |
032e8348 RS |
10367 | @end smallexample |
10368 | ||
3abcb3a7 | 10369 | Here's an example of code iterators in action, taken from the MIPS port: |
032e8348 RS |
10370 | |
10371 | @smallexample | |
3abcb3a7 HPN |
10372 | (define_code_iterator any_cond [unordered ordered unlt unge uneq ltgt unle ungt |
10373 | eq ne gt ge lt le gtu geu ltu leu]) | |
032e8348 RS |
10374 | |
10375 | (define_expand "b<code>" | |
10376 | [(set (pc) | |
10377 | (if_then_else (any_cond:CC (cc0) | |
10378 | (const_int 0)) | |
10379 | (label_ref (match_operand 0 "")) | |
10380 | (pc)))] | |
10381 | "" | |
10382 | @{ | |
10383 | gen_conditional_branch (operands, <CODE>); | |
10384 | DONE; | |
10385 | @}) | |
10386 | @end smallexample | |
10387 | ||
10388 | This is equivalent to: | |
10389 | ||
10390 | @smallexample | |
10391 | (define_expand "bunordered" | |
10392 | [(set (pc) | |
10393 | (if_then_else (unordered:CC (cc0) | |
10394 | (const_int 0)) | |
10395 | (label_ref (match_operand 0 "")) | |
10396 | (pc)))] | |
10397 | "" | |
10398 | @{ | |
10399 | gen_conditional_branch (operands, UNORDERED); | |
10400 | DONE; | |
10401 | @}) | |
10402 | ||
10403 | (define_expand "bordered" | |
10404 | [(set (pc) | |
10405 | (if_then_else (ordered:CC (cc0) | |
10406 | (const_int 0)) | |
10407 | (label_ref (match_operand 0 "")) | |
10408 | (pc)))] | |
10409 | "" | |
10410 | @{ | |
10411 | gen_conditional_branch (operands, ORDERED); | |
10412 | DONE; | |
10413 | @}) | |
10414 | ||
923158be | 10415 | @dots{} |
032e8348 RS |
10416 | @end smallexample |
10417 | ||
57a4717b TB |
10418 | @node Int Iterators |
10419 | @subsection Int Iterators | |
10420 | @cindex int iterators in @file{.md} files | |
10421 | @findex define_int_iterator | |
10422 | @findex define_int_attr | |
10423 | ||
10424 | Int iterators operate in a similar way to code iterators. @xref{Code Iterators}. | |
10425 | ||
10426 | The construct: | |
10427 | ||
10428 | @smallexample | |
10429 | (define_int_iterator @var{name} [(@var{int1} "@var{cond1}") @dots{} (@var{intn} "@var{condn}")]) | |
10430 | @end smallexample | |
10431 | ||
10432 | defines a pseudo integer constant @var{name} that can be instantiated as | |
10433 | @var{inti} if condition @var{condi} is true. Each @var{int} | |
10434 | must have the same rtx format. @xref{RTL Classes}. Int iterators can appear | |
10435 | in only those rtx fields that have 'i' as the specifier. This means that | |
10436 | each @var{int} has to be a constant defined using define_constant or | |
10437 | define_c_enum. | |
10438 | ||
10439 | As with mode and code iterators, each pattern that uses @var{name} will be | |
10440 | expanded @var{n} times, once with all uses of @var{name} replaced by | |
10441 | @var{int1}, once with all uses replaced by @var{int2}, and so on. | |
10442 | @xref{Defining Mode Iterators}. | |
10443 | ||
10444 | It is possible to define attributes for ints as well as for codes and modes. | |
10445 | Attributes are defined using: | |
10446 | ||
10447 | @smallexample | |
10448 | (define_int_attr @var{name} [(@var{int1} "@var{value1}") @dots{} (@var{intn} "@var{valuen}")]) | |
10449 | @end smallexample | |
10450 | ||
10451 | Here's an example of int iterators in action, taken from the ARM port: | |
10452 | ||
10453 | @smallexample | |
10454 | (define_int_iterator QABSNEG [UNSPEC_VQABS UNSPEC_VQNEG]) | |
10455 | ||
10456 | (define_int_attr absneg [(UNSPEC_VQABS "abs") (UNSPEC_VQNEG "neg")]) | |
10457 | ||
10458 | (define_insn "neon_vq<absneg><mode>" | |
10459 | [(set (match_operand:VDQIW 0 "s_register_operand" "=w") | |
10460 | (unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w") | |
10461 | (match_operand:SI 2 "immediate_operand" "i")] | |
10462 | QABSNEG))] | |
10463 | "TARGET_NEON" | |
10464 | "vq<absneg>.<V_s_elem>\t%<V_reg>0, %<V_reg>1" | |
003bb7f3 | 10465 | [(set_attr "type" "neon_vqneg_vqabs")] |
57a4717b TB |
10466 | ) |
10467 | ||
10468 | @end smallexample | |
10469 | ||
10470 | This is equivalent to: | |
10471 | ||
10472 | @smallexample | |
10473 | (define_insn "neon_vqabs<mode>" | |
10474 | [(set (match_operand:VDQIW 0 "s_register_operand" "=w") | |
10475 | (unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w") | |
10476 | (match_operand:SI 2 "immediate_operand" "i")] | |
10477 | UNSPEC_VQABS))] | |
10478 | "TARGET_NEON" | |
10479 | "vqabs.<V_s_elem>\t%<V_reg>0, %<V_reg>1" | |
003bb7f3 | 10480 | [(set_attr "type" "neon_vqneg_vqabs")] |
57a4717b TB |
10481 | ) |
10482 | ||
10483 | (define_insn "neon_vqneg<mode>" | |
10484 | [(set (match_operand:VDQIW 0 "s_register_operand" "=w") | |
10485 | (unspec:VDQIW [(match_operand:VDQIW 1 "s_register_operand" "w") | |
10486 | (match_operand:SI 2 "immediate_operand" "i")] | |
10487 | UNSPEC_VQNEG))] | |
10488 | "TARGET_NEON" | |
10489 | "vqneg.<V_s_elem>\t%<V_reg>0, %<V_reg>1" | |
003bb7f3 | 10490 | [(set_attr "type" "neon_vqneg_vqabs")] |
57a4717b TB |
10491 | ) |
10492 | ||
10493 | @end smallexample | |
10494 | ||
477c104e MK |
10495 | @node Subst Iterators |
10496 | @subsection Subst Iterators | |
10497 | @cindex subst iterators in @file{.md} files | |
10498 | @findex define_subst | |
10499 | @findex define_subst_attr | |
10500 | ||
10501 | Subst iterators are special type of iterators with the following | |
10502 | restrictions: they could not be declared explicitly, they always have | |
10503 | only two values, and they do not have explicit dedicated name. | |
10504 | Subst-iterators are triggered only when corresponding subst-attribute is | |
10505 | used in RTL-pattern. | |
10506 | ||
10507 | Subst iterators transform templates in the following way: the templates | |
10508 | are duplicated, the subst-attributes in these templates are replaced | |
10509 | with the corresponding values, and a new attribute is implicitly added | |
10510 | to the given @code{define_insn}/@code{define_expand}. The name of the | |
10511 | added attribute matches the name of @code{define_subst}. Such | |
10512 | attributes are declared implicitly, and it is not allowed to have a | |
10513 | @code{define_attr} named as a @code{define_subst}. | |
10514 | ||
10515 | Each subst iterator is linked to a @code{define_subst}. It is declared | |
10516 | implicitly by the first appearance of the corresponding | |
10517 | @code{define_subst_attr}, and it is not allowed to define it explicitly. | |
10518 | ||
10519 | Declarations of subst-attributes have the following syntax: | |
10520 | ||
10521 | @findex define_subst_attr | |
10522 | @smallexample | |
10523 | (define_subst_attr "@var{name}" | |
10524 | "@var{subst-name}" | |
10525 | "@var{no-subst-value}" | |
10526 | "@var{subst-applied-value}") | |
10527 | @end smallexample | |
10528 | ||
10529 | @var{name} is a string with which the given subst-attribute could be | |
10530 | referred to. | |
10531 | ||
10532 | @var{subst-name} shows which @code{define_subst} should be applied to an | |
10533 | RTL-template if the given subst-attribute is present in the | |
10534 | RTL-template. | |
10535 | ||
10536 | @var{no-subst-value} is a value with which subst-attribute would be | |
10537 | replaced in the first copy of the original RTL-template. | |
10538 | ||
10539 | @var{subst-applied-value} is a value with which subst-attribute would be | |
10540 | replaced in the second copy of the original RTL-template. | |
10541 | ||
032e8348 | 10542 | @end ifset |