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 |
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: ..."). |
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). |
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). |
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. |
20 | * Provide links to the documentation of each supported compiler, if it exists. |
21 | */ |
22 | |
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 | |
36 | /* |
37 | * Note: do not use this directly. Instead, use __alloc_size() since it is conditionally |
38 | * available and includes other attributes. For GCC < 9.1, __alloc_size__ gets undefined |
39 | * in compiler-gcc.h, due to misbehaviors. |
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 | |
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 | * |
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 | */ |
70 | #define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) |
71 | |
72 | /* |
73 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-cleanup-variable-attribute |
74 | * clang: https://clang.llvm.org/docs/AttributeReference.html#cleanup |
75 | */ |
76 | #define __cleanup(func) __attribute__((__cleanup__(func))) |
77 | |
78 | /* |
79 | * Note the long name. |
80 | * |
81 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute |
82 | */ |
83 | #define __attribute_const__ __attribute__((__const__)) |
84 | |
85 | /* |
86 | * Optional: only supported since gcc >= 9 |
87 | * Optional: not supported by clang |
88 | * |
89 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute |
90 | */ |
91 | #if __has_attribute(__copy__) |
92 | # define __copy(symbol) __attribute__((__copy__(symbol))) |
93 | #else |
94 | # define __copy(symbol) |
95 | #endif |
96 | |
97 | /* |
98 | * Optional: only supported since gcc >= 14 |
99 | * Optional: only supported since clang >= 18 |
100 | * |
101 | * gcc: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108896 |
102 | * clang: https://reviews.llvm.org/D148381 |
103 | */ |
104 | #if __has_attribute(__counted_by__) |
105 | # define __counted_by(member) __attribute__((__counted_by__(member))) |
106 | #else |
107 | # define __counted_by(member) |
108 | #endif |
109 | |
110 | /* |
111 | * Optional: not supported by gcc |
112 | * Optional: only supported since clang >= 14.0 |
113 | * |
114 | * clang: https://clang.llvm.org/docs/AttributeReference.html#diagnose_as_builtin |
115 | */ |
116 | #if __has_attribute(__diagnose_as_builtin__) |
117 | # define __diagnose_as(builtin...) __attribute__((__diagnose_as_builtin__(builtin))) |
118 | #else |
119 | # define __diagnose_as(builtin...) |
120 | #endif |
121 | |
122 | /* |
123 | * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated' |
124 | * attribute warnings entirely and for good") for more information. |
125 | * |
126 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute |
127 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute |
128 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute |
129 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute |
130 | * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated |
131 | */ |
132 | #define __deprecated |
133 | |
134 | /* |
135 | * Optional: not supported by clang |
136 | * |
137 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute |
138 | */ |
139 | #if __has_attribute(__designated_init__) |
140 | # define __designated_init __attribute__((__designated_init__)) |
141 | #else |
142 | # define __designated_init |
143 | #endif |
144 | |
145 | /* |
146 | * Optional: only supported since clang >= 14.0 |
147 | * |
148 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute |
149 | */ |
150 | #if __has_attribute(__error__) |
151 | # define __compiletime_error(msg) __attribute__((__error__(msg))) |
152 | #else |
153 | # define __compiletime_error(msg) |
154 | #endif |
155 | |
156 | /* |
157 | * Optional: not supported by clang |
158 | * |
159 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute |
160 | */ |
161 | #if __has_attribute(__externally_visible__) |
162 | # define __visible __attribute__((__externally_visible__)) |
163 | #else |
164 | # define __visible |
165 | #endif |
166 | |
167 | /* |
168 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute |
169 | * clang: https://clang.llvm.org/docs/AttributeReference.html#format |
170 | */ |
171 | #define __printf(a, b) __attribute__((__format__(printf, a, b))) |
172 | #define __scanf(a, b) __attribute__((__format__(scanf, a, b))) |
173 | |
174 | /* |
175 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute |
176 | * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline |
177 | */ |
178 | #define __gnu_inline __attribute__((__gnu_inline__)) |
179 | |
180 | /* |
181 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute |
182 | * clang: https://clang.llvm.org/docs/AttributeReference.html#malloc |
183 | */ |
184 | #define __malloc __attribute__((__malloc__)) |
185 | |
186 | /* |
187 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute |
188 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute |
189 | */ |
190 | #define __mode(x) __attribute__((__mode__(x))) |
191 | |
192 | /* |
193 | * Optional: only supported since gcc >= 7 |
194 | * |
195 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 |
196 | * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers |
197 | */ |
198 | #if __has_attribute(__no_caller_saved_registers__) |
199 | # define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__)) |
200 | #else |
201 | # define __no_caller_saved_registers |
202 | #endif |
203 | |
204 | /* |
205 | * Optional: not supported by clang |
206 | * |
207 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute |
208 | */ |
209 | #if __has_attribute(__noclone__) |
210 | # define __noclone __attribute__((__noclone__)) |
211 | #else |
212 | # define __noclone |
213 | #endif |
214 | |
215 | /* |
216 | * Add the pseudo keyword 'fallthrough' so case statement blocks |
217 | * must end with any of these keywords: |
218 | * break; |
219 | * fallthrough; |
220 | * continue; |
221 | * goto <label>; |
222 | * return [expression]; |
223 | * |
224 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes |
225 | */ |
226 | #if __has_attribute(__fallthrough__) |
227 | # define fallthrough __attribute__((__fallthrough__)) |
228 | #else |
229 | # define fallthrough do {} while (0) /* fallthrough */ |
230 | #endif |
231 | |
232 | /* |
233 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes |
234 | * clang: https://clang.llvm.org/docs/AttributeReference.html#flatten |
235 | */ |
236 | # define __flatten __attribute__((flatten)) |
237 | |
238 | /* |
239 | * Note the missing underscores. |
240 | * |
241 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute |
242 | * clang: mentioned |
243 | */ |
244 | #define noinline __attribute__((__noinline__)) |
245 | |
246 | /* |
247 | * Optional: only supported since gcc >= 8 |
248 | * Optional: not supported by clang |
249 | * |
250 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute |
251 | */ |
252 | #if __has_attribute(__nonstring__) |
253 | # define __nonstring __attribute__((__nonstring__)) |
254 | #else |
255 | # define __nonstring |
256 | #endif |
257 | |
258 | /* |
259 | * Optional: only supported since GCC >= 7.1, clang >= 13.0. |
260 | * |
261 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute |
262 | * clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function |
263 | */ |
264 | #if __has_attribute(__no_profile_instrument_function__) |
265 | # define __no_profile __attribute__((__no_profile_instrument_function__)) |
266 | #else |
267 | # define __no_profile |
268 | #endif |
269 | |
270 | /* |
271 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute |
272 | * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn |
273 | * clang: https://clang.llvm.org/docs/AttributeReference.html#id1 |
274 | */ |
275 | #define __noreturn __attribute__((__noreturn__)) |
276 | |
277 | /* |
278 | * Optional: only supported since GCC >= 11.1, clang >= 7.0. |
279 | * |
280 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fstack_005fprotector-function-attribute |
281 | * clang: https://clang.llvm.org/docs/AttributeReference.html#no-stack-protector-safebuffers |
282 | */ |
283 | #if __has_attribute(__no_stack_protector__) |
284 | # define __no_stack_protector __attribute__((__no_stack_protector__)) |
285 | #else |
286 | # define __no_stack_protector |
287 | #endif |
288 | |
289 | /* |
290 | * Optional: not supported by gcc. |
291 | * |
292 | * clang: https://clang.llvm.org/docs/AttributeReference.html#overloadable |
293 | */ |
294 | #if __has_attribute(__overloadable__) |
295 | # define __overloadable __attribute__((__overloadable__)) |
296 | #else |
297 | # define __overloadable |
298 | #endif |
299 | |
300 | /* |
301 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute |
302 | * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute |
303 | */ |
304 | #define __packed __attribute__((__packed__)) |
305 | |
306 | /* |
307 | * Note: the "type" argument should match any __builtin_object_size(p, type) usage. |
308 | * |
309 | * Optional: not supported by gcc. |
310 | * |
311 | * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size |
312 | */ |
313 | #if __has_attribute(__pass_dynamic_object_size__) |
314 | # define __pass_dynamic_object_size(type) __attribute__((__pass_dynamic_object_size__(type))) |
315 | #else |
316 | # define __pass_dynamic_object_size(type) |
317 | #endif |
318 | #if __has_attribute(__pass_object_size__) |
319 | # define __pass_object_size(type) __attribute__((__pass_object_size__(type))) |
320 | #else |
321 | # define __pass_object_size(type) |
322 | #endif |
323 | |
324 | /* |
325 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute |
326 | */ |
327 | #define __pure __attribute__((__pure__)) |
328 | |
329 | /* |
330 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute |
331 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute |
332 | * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate |
333 | */ |
334 | #define __section(section) __attribute__((__section__(section))) |
335 | |
336 | /* |
337 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute |
338 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute |
339 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute |
340 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute |
341 | * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused |
342 | */ |
343 | #define __always_unused __attribute__((__unused__)) |
344 | #define __maybe_unused __attribute__((__unused__)) |
345 | |
346 | /* |
347 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute |
348 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute |
349 | */ |
350 | #define __used __attribute__((__used__)) |
351 | |
352 | /* |
353 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute |
354 | * clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result |
355 | */ |
356 | #define __must_check __attribute__((__warn_unused_result__)) |
357 | |
358 | /* |
359 | * Optional: only supported since clang >= 14.0 |
360 | * |
361 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute |
362 | */ |
363 | #if __has_attribute(__warning__) |
364 | # define __compiletime_warning(msg) __attribute__((__warning__(msg))) |
365 | #else |
366 | # define __compiletime_warning(msg) |
367 | #endif |
368 | |
369 | /* |
370 | * Optional: only supported since clang >= 14.0 |
371 | * |
372 | * clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation |
373 | * |
374 | * disable_sanitizer_instrumentation is not always similar to |
375 | * no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers |
376 | * insert code into functions to prevent false positives. Unlike that, |
377 | * disable_sanitizer_instrumentation prevents all kinds of instrumentation to |
378 | * functions with the attribute. |
379 | */ |
380 | #if __has_attribute(disable_sanitizer_instrumentation) |
381 | # define __disable_sanitizer_instrumentation \ |
382 | __attribute__((disable_sanitizer_instrumentation)) |
383 | #else |
384 | # define __disable_sanitizer_instrumentation |
385 | #endif |
386 | |
387 | /* |
388 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute |
389 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute |
390 | */ |
391 | #define __weak __attribute__((__weak__)) |
392 | |
393 | /* |
394 | * Used by functions that use '__builtin_return_address'. These function |
395 | * don't want to be splited or made inline, which can make |
396 | * the '__builtin_return_address' get unexpected address. |
397 | */ |
398 | #define __fix_address noinline __noclone |
399 | |
400 | #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ |
401 | |