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1 | .. |
2 | Copyright 1988-2022 Free Software Foundation, Inc. | |
3 | This is part of the GCC manual. | |
4 | For copying conditions, see the copyright.rst file. | |
5 | ||
6 | .. _option-properties: | |
7 | ||
8 | Option properties | |
9 | ***************** | |
10 | ||
11 | The second field of an option record can specify any of the following | |
12 | properties. When an option takes an argument, it is enclosed in parentheses | |
13 | following the option property name. The parser that handles option files | |
14 | is quite simplistic, and will be tricked by any nested parentheses within | |
15 | the argument text itself; in this case, the entire option argument can | |
16 | be wrapped in curly braces within the parentheses to demarcate it, e.g.: | |
17 | ||
18 | .. code-block:: c++ | |
19 | ||
20 | Condition({defined (USE_CYGWIN_LIBSTDCXX_WRAPPERS)}) | |
21 | ||
22 | ``Common`` | |
23 | The option is available for all languages and targets. | |
24 | ||
25 | ``Target`` | |
26 | The option is available for all languages but is target-specific. | |
27 | ||
28 | ``Driver`` | |
29 | The option is handled by the compiler driver using code not shared | |
30 | with the compilers proper (:samp:`cc1` etc.). | |
31 | ||
32 | ``language`` | |
33 | The option is available when compiling for the given language. | |
34 | ||
35 | It is possible to specify several different languages for the same | |
36 | option. Each :samp:`{language}` must have been declared by an earlier | |
37 | ``Language`` record. See :ref:`option-file-format`. | |
38 | ||
39 | ``RejectDriver`` | |
40 | The option is only handled by the compilers proper (:samp:`cc1` etc.) | |
41 | and should not be accepted by the driver. | |
42 | ||
43 | ``RejectNegative`` | |
44 | The option does not have a 'no-' form. All options beginning with | |
45 | 'f', 'W' or 'm' are assumed to have a 'no-' form unless this | |
46 | property is used. | |
47 | ||
48 | :samp:`Negative({othername})` | |
49 | The option will turn off another option :samp:`{othername}`, which is | |
50 | the option name with the leading '-' removed. This chain action will | |
51 | propagate through the ``Negative`` property of the option to be | |
52 | turned off. The driver will prune options, removing those that are | |
53 | turned off by some later option. This pruning is not done for options | |
54 | with ``Joined`` or ``JoinedOrMissing`` properties, unless the | |
55 | options have both the ``RejectNegative`` property and the ``Negative`` | |
56 | property mentions itself. | |
57 | ||
58 | As a consequence, if you have a group of mutually-exclusive | |
59 | options, their ``Negative`` properties should form a circular chain. | |
60 | For example, if options :option:`-a`, :option:`-b` and | |
61 | :option:`-c` are mutually exclusive, their respective ``Negative`` | |
62 | properties should be :samp:`Negative({b})`, :samp:`Negative({c})` | |
63 | and :samp:`Negative({a})`. | |
64 | ||
65 | ``Joined`` ``Separate`` | |
66 | The option takes a mandatory argument. ``Joined`` indicates | |
67 | that the option and argument can be included in the same ``argv`` | |
68 | entry (as with ``-mflush-func=name``, for example). | |
69 | ``Separate`` indicates that the option and argument can be | |
70 | separate ``argv`` entries (as with ``-o``). An option is | |
71 | allowed to have both of these properties. | |
72 | ||
73 | ``JoinedOrMissing`` | |
74 | The option takes an optional argument. If the argument is given, | |
75 | it will be part of the same ``argv`` entry as the option itself. | |
76 | ||
77 | This property cannot be used alongside ``Joined`` or ``Separate``. | |
78 | ||
79 | :samp:`MissingArgError({message})` | |
80 | For an option marked ``Joined`` or ``Separate``, the message | |
81 | :samp:`{message}` will be used as an error message if the mandatory | |
82 | argument is missing; for options without ``MissingArgError``, a | |
83 | generic error message is used. :samp:`{message}` should contain a single | |
84 | :samp:`%qs` format, which will be used to format the name of the option | |
85 | passed. | |
86 | ||
87 | :samp:`Args({n})` | |
88 | For an option marked ``Separate``, indicate that it takes :samp:`{n}` | |
89 | arguments. The default is 1. | |
90 | ||
91 | ``UInteger`` | |
92 | The option's argument is a non-negative integer consisting of either | |
93 | decimal or hexadecimal digits interpreted as ``int``. Hexadecimal | |
94 | integers may optionally start with the ``0x`` or ``0X`` prefix. | |
95 | The option parser validates and converts the argument before passing | |
96 | it to the relevant option handler. ``UInteger`` should also be used | |
97 | with options like ``-falign-loops`` where both ``-falign-loops`` | |
98 | and ``-falign-loops`` = :samp:`{n}` are supported to make sure the saved | |
99 | options are given a full integer. Positive values of the argument in | |
100 | excess of ``INT_MAX`` wrap around zero. | |
101 | ||
102 | ``Host_Wide_Int`` | |
103 | The option's argument is a non-negative integer consisting of either | |
104 | decimal or hexadecimal digits interpreted as the widest integer type | |
105 | on the host. As with an ``UInteger`` argument, hexadecimal integers | |
106 | may optionally start with the ``0x`` or ``0X`` prefix. The option | |
107 | parser validates and converts the argument before passing it to | |
108 | the relevant option handler. ``Host_Wide_Int`` should be used with | |
109 | options that need to accept very large values. Positive values of | |
110 | the argument in excess of ``HOST_WIDE_INT_M1U`` are assigned | |
111 | ``HOST_WIDE_INT_M1U``. | |
112 | ||
113 | :samp:`IntegerRange({n}, {m})` | |
114 | The options's arguments are integers of type ``int``. The option's | |
115 | parser validates that the value of an option integer argument is within | |
116 | the closed range [ :samp:`{n}`, :samp:`{m}` ]. | |
117 | ||
118 | ``ByteSize`` | |
119 | A property applicable only to ``UInteger`` or ``Host_Wide_Int`` | |
120 | arguments. The option's integer argument is interpreted as if in infinite | |
121 | precision using saturation arithmetic in the corresponding type. The argument | |
122 | may be followed by a :samp:`byte-size` suffix designating a multiple of bytes | |
123 | such as ``kB`` and ``KiB`` for kilobyte and kibibyte, respectively, | |
124 | ``MB`` and ``MiB`` for megabyte and mebibyte, ``GB`` and ``GiB`` | |
125 | for gigabyte and gigibyte, and so on. ``ByteSize`` should be used for | |
126 | with options that take a very large argument representing a size in bytes, | |
127 | such as :option:`-Wlarger-than=`. | |
128 | ||
129 | ``ToLower`` | |
130 | The option's argument should be converted to lowercase as part of | |
131 | putting it in canonical form, and before comparing with the strings | |
132 | indicated by any ``Enum`` property. | |
133 | ||
134 | ``NoDriverArg`` | |
135 | For an option marked ``Separate``, the option only takes an | |
136 | argument in the compiler proper, not in the driver. This is for | |
137 | compatibility with existing options that are used both directly and | |
138 | via :option:`-Wp,` ; new options should not have this property. | |
139 | ||
140 | :samp:`Var({var})` | |
141 | The state of this option should be stored in variable :samp:`{var}` | |
142 | (actually a macro for ``global_options.x_var``). | |
143 | The way that the state is stored depends on the type of option: | |
144 | ||
145 | ``WarnRemoved`` | |
146 | The option is removed and every usage of such option will | |
147 | result in a warning. We use it option backward compatibility. | |
148 | ||
149 | :samp:`Var({var}, {set})` | |
150 | The option controls an integer variable :samp:`{var}` and is active when | |
151 | :samp:`{var}` equals :samp:`{set}`. The option parser will set :samp:`{var}` to | |
152 | :samp:`{set}` when the positive form of the option is used and ``!set`` | |
153 | when the 'no-' form is used. | |
154 | ||
155 | :samp:`{var}` is declared in the same way as for the single-argument form | |
156 | described above. | |
157 | ||
158 | * If the option uses the ``Mask`` or ``InverseMask`` properties, | |
159 | :samp:`{var}` is the integer variable that contains the mask. | |
160 | ||
161 | * If the option is a normal on/off switch, :samp:`{var}` is an integer | |
162 | variable that is nonzero when the option is enabled. The options | |
163 | parser will set the variable to 1 when the positive form of the | |
164 | option is used and 0 when the 'no-' form is used. | |
165 | ||
166 | * If the option takes an argument and has the ``UInteger`` property, | |
167 | :samp:`{var}` is an integer variable that stores the value of the argument. | |
168 | ||
169 | * If the option takes an argument and has the ``Enum`` property, | |
170 | :samp:`{var}` is a variable (type given in the ``Type`` property of the | |
171 | :samp:`Enum` record whose ``Name`` property has the same argument as | |
172 | the ``Enum`` property of this option) that stores the value of the | |
173 | argument. | |
174 | ||
175 | * If the option has the ``Defer`` property, :samp:`{var}` is a pointer to | |
176 | a ``VEC(cl_deferred_option,heap)`` that stores the option for later | |
177 | processing. (:samp:`{var}` is declared with type ``void *`` and needs | |
178 | to be cast to ``VEC(cl_deferred_option,heap)`` before use.) | |
179 | ||
180 | * Otherwise, if the option takes an argument, :samp:`{var}` is a pointer to | |
181 | the argument string. The pointer will be null if the argument is optional | |
182 | and wasn't given. | |
183 | ||
184 | The option-processing script will usually zero-initialize :samp:`{var}`. | |
185 | You can modify this behavior using ``Init``. | |
186 | ||
187 | :samp:`Init({value})` | |
188 | The variable specified by the ``Var`` property should be statically | |
189 | initialized to :samp:`{value}`. If more than one option using the same | |
190 | variable specifies ``Init``, all must specify the same initializer. | |
191 | ||
192 | :samp:`Mask({name})` | |
193 | The option is associated with a bit in the ``target_flags`` | |
194 | variable (see :ref:`run-time-target`) and is active when that bit is set. | |
195 | You may also specify ``Var`` to select a variable other than | |
196 | ``target_flags``. | |
197 | ||
198 | The options-processing script will automatically allocate a unique bit | |
199 | for the option. If the option is attached to :samp:`target_flags`, | |
200 | the script will set the macro ``MASK_name`` to the appropriate | |
201 | bitmask. It will also declare a ``TARGET_name`` macro that has | |
202 | the value 1 when the option is active and 0 otherwise. If you use ``Var`` | |
203 | to attach the option to a different variable, the bitmask macro with be | |
204 | called ``OPTION_MASK_name``. | |
205 | ||
206 | :samp:`InverseMask({othername})` :samp:`InverseMask({othername}, {thisname})` | |
207 | The option is the inverse of another option that has the | |
208 | ``Mask(othername)`` property. If :samp:`{thisname}` is given, | |
209 | the options-processing script will declare a ``TARGET_thisname`` | |
210 | macro that is 1 when the option is active and 0 otherwise. | |
211 | ||
212 | :samp:`Enum({name})` | |
213 | The option's argument is a string from the set of strings associated | |
214 | with the corresponding :samp:`Enum` record. The string is checked and | |
215 | converted to the integer specified in the corresponding | |
216 | :samp:`EnumValue` record before being passed to option handlers. | |
217 | ||
218 | ``EnumSet`` | |
219 | Must be used together with the ``Enum(name)`` property. | |
220 | Corresponding :samp:`Enum` record must use ``Set`` properties. | |
221 | The option's argument is either a string from the set like for | |
222 | ``Enum(name)``, but with a slightly different behavior that | |
223 | the whole ``Var`` isn't overwritten, but only the bits in all the | |
224 | enumeration values with the same set bitwise ored together. | |
225 | Or option's argument can be a comma separated list of strings where | |
226 | each string is from a different ``Set(number)``. | |
227 | ||
228 | ``EnumBitSet`` | |
229 | Must be used together with the ``Enum(name)`` property. | |
230 | Similar to :samp:`EnumSet`, but corresponding :samp:`Enum` record must | |
231 | not use ``Set`` properties, each ``EnumValue`` should have | |
232 | ``Value`` that is a power of 2, each value is treated as its own | |
233 | set and its value as the set's mask, so there are no mutually | |
234 | exclusive arguments. | |
235 | ||
236 | ``Defer`` | |
237 | The option should be stored in a vector, specified with ``Var``, | |
238 | for later processing. | |
239 | ||
240 | :samp:`Alias({opt})` :samp:`Alias({opt}, {arg})` :samp:`Alias({opt}, {posarg}, {negarg})` | |
241 | The option is an alias for :option:`-opt` (or the negative form | |
242 | of that option, depending on ``NegativeAlias``). In the first form, | |
243 | any argument passed to the alias is considered to be passed to | |
244 | :option:`-opt`, and :option:`-opt` is considered to be | |
245 | negated if the alias is used in negated form. In the second form, the | |
246 | alias may not be negated or have an argument, and :samp:`{posarg}` is | |
247 | considered to be passed as an argument to :option:`-opt`. In the | |
248 | third form, the alias may not have an argument, if the alias is used | |
249 | in the positive form then :samp:`{posarg}` is considered to be passed to | |
250 | :option:`-opt`, and if the alias is used in the negative form | |
251 | then :samp:`{negarg}` is considered to be passed to :option:`-opt`. | |
252 | ||
253 | Aliases should not specify ``Var`` or ``Mask`` or | |
254 | ``UInteger``. Aliases should normally specify the same languages | |
255 | as the target of the alias; the flags on the target will be used to | |
256 | determine any diagnostic for use of an option for the wrong language, | |
257 | while those on the alias will be used to identify what command-line | |
258 | text is the option and what text is any argument to that option. | |
259 | ||
260 | When an ``Alias`` definition is used for an option, driver specs do | |
261 | not need to handle it and no :samp:`OPT_` enumeration value is defined | |
262 | for it; only the canonical form of the option will be seen in those | |
263 | places. | |
264 | ||
265 | ``NegativeAlias`` | |
266 | For an option marked with ``Alias(opt)``, the option is | |
267 | considered to be an alias for the positive form of :option:`-opt` | |
268 | if negated and for the negative form of :option:`-opt` if not | |
269 | negated. ``NegativeAlias`` may not be used with the forms of | |
270 | ``Alias`` taking more than one argument. | |
271 | ||
272 | ``Ignore`` | |
273 | This option is ignored apart from printing any warning specified using | |
274 | ``Warn``. The option will not be seen by specs and no :samp:`OPT_` | |
275 | enumeration value is defined for it. | |
276 | ||
277 | ``SeparateAlias`` | |
278 | For an option marked with ``Joined``, ``Separate`` and | |
279 | ``Alias``, the option only acts as an alias when passed a separate | |
280 | argument; with a joined argument it acts as a normal option, with an | |
281 | :samp:`OPT_` enumeration value. This is for compatibility with the | |
282 | Java :option:`-d` option and should not be used for new options. | |
283 | ||
284 | :samp:`Warn({message})` | |
285 | If this option is used, output the warning :samp:`{message}`. | |
286 | :samp:`{message}` is a format string, either taking a single operand with | |
287 | a :samp:`%qs` format which is the option name, or not taking any | |
288 | operands, which is passed to the :samp:`warning` function. If an alias | |
289 | is marked ``Warn``, the target of the alias must not also be marked | |
290 | ``Warn``. | |
291 | ||
292 | ``Warning`` | |
293 | This is a warning option and should be shown as such in | |
294 | :option:`--help` output. This flag does not currently affect anything | |
295 | other than :option:`--help`. | |
296 | ||
297 | ``Optimization`` | |
298 | This is an optimization option. It should be shown as such in | |
299 | :option:`--help` output, and any associated variable named using | |
300 | ``Var`` should be saved and restored when the optimization level is | |
301 | changed with ``optimize`` attributes. | |
302 | ||
303 | ``PerFunction`` | |
304 | This is an option that can be overridden on a per-function basis. | |
305 | ``Optimization`` implies ``PerFunction``, but options that do not | |
306 | affect executable code generation may use this flag instead, so that the | |
307 | option is not taken into account in ways that might affect executable | |
308 | code generation. | |
309 | ||
310 | ``Param`` | |
311 | This is an option that is a parameter. | |
312 | ||
313 | ``Undocumented`` | |
314 | The option is deliberately missing documentation and should not | |
315 | be included in the :option:`--help` output. | |
316 | ||
317 | :samp:`Condition({cond})` | |
318 | The option should only be accepted if preprocessor condition | |
319 | :samp:`{cond}` is true. Note that any C declarations associated with the | |
320 | option will be present even if :samp:`{cond}` is false; :samp:`{cond}` simply | |
321 | controls whether the option is accepted and whether it is printed in | |
322 | the :option:`--help` output. | |
323 | ||
324 | ``Save`` | |
325 | Build the ``cl_target_option`` structure to hold a copy of the | |
326 | option, add the functions ``cl_target_option_save`` and | |
327 | ``cl_target_option_restore`` to save and restore the options. | |
328 | ||
329 | ``SetByCombined`` | |
330 | The option may also be set by a combined option such as | |
331 | :option:`-ffast-math`. This causes the ``gcc_options`` struct to | |
332 | have a field ``frontend_set_name``, where ``name`` | |
333 | is the name of the field holding the value of this option (without the | |
334 | leading ``x_``). This gives the front end a way to indicate that | |
335 | the value has been set explicitly and should not be changed by the | |
336 | combined option. For example, some front ends use this to prevent | |
337 | :option:`-ffast-math` and :option:`-fno-fast-math` from changing the | |
338 | value of :option:`-fmath-errno` for languages that do not use | |
339 | ``errno``. | |
340 | ||
341 | :samp:`EnabledBy({opt})` :samp:`EnabledBy({opt} || {opt2})` :samp:`EnabledBy({opt} && {opt2})` | |
342 | If not explicitly set, the option is set to the value of | |
343 | :option:`-opt` ; multiple options can be given, separated by | |
344 | ``||``. The third form using ``&&`` specifies that the option is | |
345 | only set if both :samp:`{opt}` and :samp:`{opt2}` are set. The options :samp:`{opt}` | |
346 | and :samp:`{opt2}` must have the ``Common`` property; otherwise, use | |
347 | ``LangEnabledBy``. | |
348 | ||
349 | :samp:`LangEnabledBy({language}, {opt})` :samp:`LangEnabledBy({language}, {opt}, {posarg}, {negarg})` | |
350 | When compiling for the given language, the option is set to the value | |
351 | of :option:`-opt`, if not explicitly set. :samp:`{opt}` can be also a list | |
352 | of ``||`` separated options. In the second form, if | |
353 | :samp:`{opt}` is used in the positive form then :samp:`{posarg}` is considered | |
354 | to be passed to the option, and if :samp:`{opt}` is used in the negative | |
355 | form then :samp:`{negarg}` is considered to be passed to the option. It | |
356 | is possible to specify several different languages. Each | |
357 | :samp:`{language}` must have been declared by an earlier ``Language`` | |
358 | record. See :ref:`option-file-format`. | |
359 | ||
360 | ``NoDWARFRecord`` | |
361 | The option is omitted from the producer string written by | |
362 | :option:`-grecord-gcc-switches`. | |
363 | ||
364 | ``PchIgnore`` | |
365 | Even if this is a target option, this option will not be recorded / compared | |
366 | to determine if a precompiled header file matches. | |
367 | ||
368 | :samp:`CPP({var})` | |
369 | The state of this option should be kept in sync with the preprocessor | |
370 | option :samp:`{var}`. If this property is set, then properties ``Var`` | |
371 | and ``Init`` must be set as well. | |
372 | ||
373 | :samp:`CppReason({CPP_W_Enum})` | |
374 | This warning option corresponds to ``cpplib.h`` warning reason code | |
375 | :samp:`{CPP_W_Enum}`. This should only be used for warning options of the | |
3ed1b4ce | 376 | C-family front-ends. |