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a3f8a30f MO |
1 | /* SPDX-License-Identifier: GPL-2.0 */ |
2 | #ifndef __LINUX_COMPILER_ATTRIBUTES_H | |
3 | #define __LINUX_COMPILER_ATTRIBUTES_H | |
4 | ||
5 | /* | |
6 | * The attributes in this file are unconditionally defined and they directly | |
24efee41 MO |
7 | * map to compiler attribute(s), unless one of the compilers does not support |
8 | * the attribute. In that case, __has_attribute is used to check for support | |
9 | * and the reason is stated in its comment ("Optional: ..."). | |
a3f8a30f MO |
10 | * |
11 | * Any other "attributes" (i.e. those that depend on a configuration option, | |
12 | * on a compiler, on an architecture, on plugins, on other attributes...) | |
13 | * should be defined elsewhere (e.g. compiler_types.h or compiler-*.h). | |
24efee41 MO |
14 | * The intention is to keep this file as simple as possible, as well as |
15 | * compiler- and version-agnostic (e.g. avoiding GCC_VERSION checks). | |
a3f8a30f MO |
16 | * |
17 | * This file is meant to be sorted (by actual attribute name, | |
18 | * not by #define identifier). Use the __attribute__((__name__)) syntax | |
19 | * (i.e. with underscores) to avoid future collisions with other macros. | |
24efee41 | 20 | * Provide links to the documentation of each supported compiler, if it exists. |
a3f8a30f MO |
21 | */ |
22 | ||
a3f8a30f MO |
23 | /* |
24 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute | |
25 | */ | |
26 | #define __alias(symbol) __attribute__((__alias__(#symbol))) | |
27 | ||
28 | /* | |
29 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute | |
30 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute | |
31 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute | |
32 | */ | |
33 | #define __aligned(x) __attribute__((__aligned__(x))) | |
34 | #define __aligned_largest __attribute__((__aligned__)) | |
35 | ||
86cffecd KC |
36 | /* |
37 | * Note: do not use this directly. Instead, use __alloc_size() since it is conditionally | |
9ed9cac1 KC |
38 | * available and includes other attributes. For GCC < 9.1, __alloc_size__ gets undefined |
39 | * in compiler-gcc.h, due to misbehaviors. | |
86cffecd KC |
40 | * |
41 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alloc_005fsize-function-attribute | |
42 | * clang: https://clang.llvm.org/docs/AttributeReference.html#alloc-size | |
43 | */ | |
44 | #define __alloc_size__(x, ...) __attribute__((__alloc_size__(x, ## __VA_ARGS__))) | |
45 | ||
a3f8a30f MO |
46 | /* |
47 | * Note: users of __always_inline currently do not write "inline" themselves, | |
48 | * which seems to be required by gcc to apply the attribute according | |
49 | * to its docs (and also "warning: always_inline function might not be | |
50 | * inlinable [-Wattributes]" is emitted). | |
51 | * | |
52 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute | |
53 | * clang: mentioned | |
54 | */ | |
55 | #define __always_inline inline __attribute__((__always_inline__)) | |
56 | ||
57 | /* | |
58 | * The second argument is optional (default 0), so we use a variadic macro | |
59 | * to make the shorthand. | |
60 | * | |
61 | * Beware: Do not apply this to functions which may return | |
62 | * ERR_PTRs. Also, it is probably unwise to apply it to functions | |
63 | * returning extra information in the low bits (but in that case the | |
64 | * compiler should see some alignment anyway, when the return value is | |
65 | * massaged by 'flags = ptr & 3; ptr &= ~3;'). | |
66 | * | |
a3f8a30f MO |
67 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute |
68 | * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned | |
69 | */ | |
95207db8 | 70 | #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) |
a3f8a30f | 71 | |
a3f8a30f MO |
72 | /* |
73 | * Note the long name. | |
74 | * | |
75 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute | |
76 | */ | |
77 | #define __attribute_const__ __attribute__((__const__)) | |
78 | ||
c0d9782f MO |
79 | /* |
80 | * Optional: only supported since gcc >= 9 | |
81 | * Optional: not supported by clang | |
c0d9782f MO |
82 | * |
83 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute | |
84 | */ | |
85 | #if __has_attribute(__copy__) | |
86 | # define __copy(symbol) __attribute__((__copy__(symbol))) | |
87 | #else | |
88 | # define __copy(symbol) | |
89 | #endif | |
90 | ||
1c7f4e5c KC |
91 | /* |
92 | * Optional: not supported by gcc | |
93 | * Optional: only supported since clang >= 14.0 | |
1c7f4e5c KC |
94 | * |
95 | * clang: https://clang.llvm.org/docs/AttributeReference.html#diagnose_as_builtin | |
96 | */ | |
97 | #if __has_attribute(__diagnose_as_builtin__) | |
98 | # define __diagnose_as(builtin...) __attribute__((__diagnose_as_builtin__(builtin))) | |
99 | #else | |
100 | # define __diagnose_as(builtin...) | |
101 | #endif | |
102 | ||
a3f8a30f MO |
103 | /* |
104 | * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated' | |
105 | * attribute warnings entirely and for good") for more information. | |
106 | * | |
107 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute | |
108 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute | |
109 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute | |
110 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute | |
111 | * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated | |
112 | */ | |
113 | #define __deprecated | |
114 | ||
115 | /* | |
a3f8a30f | 116 | * Optional: not supported by clang |
a3f8a30f MO |
117 | * |
118 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute | |
119 | */ | |
120 | #if __has_attribute(__designated_init__) | |
121 | # define __designated_init __attribute__((__designated_init__)) | |
122 | #else | |
123 | # define __designated_init | |
124 | #endif | |
125 | ||
b83a9084 ND |
126 | /* |
127 | * Optional: only supported since clang >= 14.0 | |
128 | * | |
129 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute | |
130 | */ | |
131 | #if __has_attribute(__error__) | |
132 | # define __compiletime_error(msg) __attribute__((__error__(msg))) | |
133 | #else | |
134 | # define __compiletime_error(msg) | |
135 | #endif | |
136 | ||
a3f8a30f MO |
137 | /* |
138 | * Optional: not supported by clang | |
139 | * | |
140 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute | |
141 | */ | |
142 | #if __has_attribute(__externally_visible__) | |
143 | # define __visible __attribute__((__externally_visible__)) | |
144 | #else | |
145 | # define __visible | |
146 | #endif | |
147 | ||
148 | /* | |
149 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute | |
150 | * clang: https://clang.llvm.org/docs/AttributeReference.html#format | |
151 | */ | |
152 | #define __printf(a, b) __attribute__((__format__(printf, a, b))) | |
153 | #define __scanf(a, b) __attribute__((__format__(scanf, a, b))) | |
154 | ||
155 | /* | |
156 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute | |
157 | * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline | |
158 | */ | |
159 | #define __gnu_inline __attribute__((__gnu_inline__)) | |
160 | ||
161 | /* | |
162 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute | |
86cffecd | 163 | * clang: https://clang.llvm.org/docs/AttributeReference.html#malloc |
a3f8a30f MO |
164 | */ |
165 | #define __malloc __attribute__((__malloc__)) | |
166 | ||
167 | /* | |
168 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute | |
169 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute | |
170 | */ | |
171 | #define __mode(x) __attribute__((__mode__(x))) | |
172 | ||
feee1b8c AP |
173 | /* |
174 | * Optional: only supported since gcc >= 7 | |
175 | * | |
176 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 | |
177 | * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers | |
178 | */ | |
179 | #if __has_attribute(__no_caller_saved_registers__) | |
180 | # define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__)) | |
181 | #else | |
182 | # define __no_caller_saved_registers | |
183 | #endif | |
184 | ||
a3f8a30f MO |
185 | /* |
186 | * Optional: not supported by clang | |
a3f8a30f MO |
187 | * |
188 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute | |
a3f8a30f MO |
189 | */ |
190 | #if __has_attribute(__noclone__) | |
2bcbd406 | 191 | # define __noclone __attribute__((__noclone__)) |
a3f8a30f MO |
192 | #else |
193 | # define __noclone | |
294f69e6 JP |
194 | #endif |
195 | ||
196 | /* | |
197 | * Add the pseudo keyword 'fallthrough' so case statement blocks | |
198 | * must end with any of these keywords: | |
199 | * break; | |
200 | * fallthrough; | |
ca0760e7 | 201 | * continue; |
294f69e6 JP |
202 | * goto <label>; |
203 | * return [expression]; | |
204 | * | |
205 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes | |
206 | */ | |
207 | #if __has_attribute(__fallthrough__) | |
208 | # define fallthrough __attribute__((__fallthrough__)) | |
209 | #else | |
210 | # define fallthrough do {} while (0) /* fallthrough */ | |
a3f8a30f MO |
211 | #endif |
212 | ||
258e0815 DZ |
213 | /* |
214 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes | |
215 | * clang: https://clang.llvm.org/docs/AttributeReference.html#flatten | |
216 | */ | |
217 | # define __flatten __attribute__((flatten)) | |
218 | ||
a3f8a30f MO |
219 | /* |
220 | * Note the missing underscores. | |
221 | * | |
222 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute | |
223 | * clang: mentioned | |
224 | */ | |
225 | #define noinline __attribute__((__noinline__)) | |
226 | ||
92676236 MO |
227 | /* |
228 | * Optional: only supported since gcc >= 8 | |
229 | * Optional: not supported by clang | |
92676236 MO |
230 | * |
231 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute | |
232 | */ | |
233 | #if __has_attribute(__nonstring__) | |
234 | # define __nonstring __attribute__((__nonstring__)) | |
235 | #else | |
236 | # define __nonstring | |
237 | #endif | |
238 | ||
380d53c4 ND |
239 | /* |
240 | * Optional: only supported since GCC >= 7.1, clang >= 13.0. | |
241 | * | |
242 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute | |
243 | * clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function | |
244 | */ | |
245 | #if __has_attribute(__no_profile_instrument_function__) | |
246 | # define __no_profile __attribute__((__no_profile_instrument_function__)) | |
247 | #else | |
248 | # define __no_profile | |
249 | #endif | |
250 | ||
a3f8a30f MO |
251 | /* |
252 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute | |
253 | * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn | |
254 | * clang: https://clang.llvm.org/docs/AttributeReference.html#id1 | |
255 | */ | |
256 | #define __noreturn __attribute__((__noreturn__)) | |
257 | ||
d694dbae KC |
258 | /* |
259 | * Optional: not supported by gcc. | |
d694dbae KC |
260 | * |
261 | * clang: https://clang.llvm.org/docs/AttributeReference.html#overloadable | |
262 | */ | |
263 | #if __has_attribute(__overloadable__) | |
264 | # define __overloadable __attribute__((__overloadable__)) | |
265 | #else | |
266 | # define __overloadable | |
267 | #endif | |
268 | ||
a3f8a30f MO |
269 | /* |
270 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute | |
271 | * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute | |
272 | */ | |
273 | #define __packed __attribute__((__packed__)) | |
274 | ||
f0202b8c KC |
275 | /* |
276 | * Note: the "type" argument should match any __builtin_object_size(p, type) usage. | |
277 | * | |
278 | * Optional: not supported by gcc. | |
f0202b8c KC |
279 | * |
280 | * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size | |
281 | */ | |
439a1bca KC |
282 | #if __has_attribute(__pass_dynamic_object_size__) |
283 | # define __pass_dynamic_object_size(type) __attribute__((__pass_dynamic_object_size__(type))) | |
284 | #else | |
285 | # define __pass_dynamic_object_size(type) | |
286 | #endif | |
f0202b8c KC |
287 | #if __has_attribute(__pass_object_size__) |
288 | # define __pass_object_size(type) __attribute__((__pass_object_size__(type))) | |
289 | #else | |
290 | # define __pass_object_size(type) | |
291 | #endif | |
292 | ||
a3f8a30f MO |
293 | /* |
294 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute | |
295 | */ | |
296 | #define __pure __attribute__((__pure__)) | |
297 | ||
298 | /* | |
299 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute | |
300 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute | |
301 | * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate | |
302 | */ | |
33def849 | 303 | #define __section(section) __attribute__((__section__(section))) |
a3f8a30f MO |
304 | |
305 | /* | |
306 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute | |
307 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute | |
308 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute | |
309 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute | |
310 | * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused | |
311 | */ | |
312 | #define __always_unused __attribute__((__unused__)) | |
313 | #define __maybe_unused __attribute__((__unused__)) | |
314 | ||
315 | /* | |
316 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute | |
317 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute | |
318 | */ | |
319 | #define __used __attribute__((__used__)) | |
320 | ||
19679394 MY |
321 | /* |
322 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute | |
323 | * clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result | |
324 | */ | |
325 | #define __must_check __attribute__((__warn_unused_result__)) | |
326 | ||
b83a9084 ND |
327 | /* |
328 | * Optional: only supported since clang >= 14.0 | |
329 | * | |
330 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute | |
331 | */ | |
332 | #if __has_attribute(__warning__) | |
333 | # define __compiletime_warning(msg) __attribute__((__warning__(msg))) | |
334 | #else | |
335 | # define __compiletime_warning(msg) | |
336 | #endif | |
337 | ||
a015b708 AP |
338 | /* |
339 | * Optional: only supported since clang >= 14.0 | |
340 | * | |
341 | * clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation | |
342 | * | |
343 | * disable_sanitizer_instrumentation is not always similar to | |
344 | * no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers | |
345 | * insert code into functions to prevent false positives. Unlike that, | |
346 | * disable_sanitizer_instrumentation prevents all kinds of instrumentation to | |
347 | * functions with the attribute. | |
348 | */ | |
349 | #if __has_attribute(disable_sanitizer_instrumentation) | |
350 | # define __disable_sanitizer_instrumentation \ | |
351 | __attribute__((disable_sanitizer_instrumentation)) | |
352 | #else | |
353 | # define __disable_sanitizer_instrumentation | |
354 | #endif | |
355 | ||
a3f8a30f MO |
356 | /* |
357 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute | |
358 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute | |
359 | */ | |
360 | #define __weak __attribute__((__weak__)) | |
361 | ||
c205cc75 MD |
362 | /* |
363 | * Used by functions that use '__builtin_return_address'. These function | |
364 | * don't want to be splited or made inline, which can make | |
365 | * the '__builtin_return_address' get unexpected address. | |
366 | */ | |
367 | #define __fix_address noinline __noclone | |
368 | ||
a3f8a30f | 369 | #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ |