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 * Optional: not supported by icc 68 * 69 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute 70 * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned 71 */ 72 #if __has_attribute(__assume_aligned__) 73 # define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) 74 #else 75 # define __assume_aligned(a, ...) 76 #endif 77 78 /* 79 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute 80 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute 81 */ 82 #define __cold __attribute__((__cold__)) 83 84 /* 85 * Note the long name. 86 * 87 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute 88 */ 89 #define __attribute_const__ __attribute__((__const__)) 90 91 /* 92 * Optional: only supported since gcc >= 9 93 * Optional: not supported by clang 94 * Optional: not supported by icc 95 * 96 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute 97 */ 98 #if __has_attribute(__copy__) 99 # define __copy(symbol) __attribute__((__copy__(symbol))) 100 #else 101 # define __copy(symbol) 102 #endif 103 104 /* 105 * Optional: not supported by gcc 106 * Optional: only supported since clang >= 14.0 107 * Optional: not supported by icc 108 * 109 * clang: https://clang.llvm.org/docs/AttributeReference.html#diagnose_as_builtin 110 */ 111 #if __has_attribute(__diagnose_as_builtin__) 112 # define __diagnose_as(builtin...) __attribute__((__diagnose_as_builtin__(builtin))) 113 #else 114 # define __diagnose_as(builtin...) 115 #endif 116 117 /* 118 * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated' 119 * attribute warnings entirely and for good") for more information. 120 * 121 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute 122 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute 123 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute 124 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute 125 * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated 126 */ 127 #define __deprecated 128 129 /* 130 * Optional: not supported by clang 131 * Optional: not supported by icc 132 * 133 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute 134 */ 135 #if __has_attribute(__designated_init__) 136 # define __designated_init __attribute__((__designated_init__)) 137 #else 138 # define __designated_init 139 #endif 140 141 /* 142 * Optional: only supported since clang >= 14.0 143 * 144 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute 145 */ 146 #if __has_attribute(__error__) 147 # define __compiletime_error(msg) __attribute__((__error__(msg))) 148 #else 149 # define __compiletime_error(msg) 150 #endif 151 152 /* 153 * Optional: not supported by clang 154 * 155 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute 156 */ 157 #if __has_attribute(__externally_visible__) 158 # define __visible __attribute__((__externally_visible__)) 159 #else 160 # define __visible 161 #endif 162 163 /* 164 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute 165 * clang: https://clang.llvm.org/docs/AttributeReference.html#format 166 */ 167 #define __printf(a, b) __attribute__((__format__(printf, a, b))) 168 #define __scanf(a, b) __attribute__((__format__(scanf, a, b))) 169 170 /* 171 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute 172 * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline 173 */ 174 #define __gnu_inline __attribute__((__gnu_inline__)) 175 176 /* 177 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute 178 * clang: https://clang.llvm.org/docs/AttributeReference.html#malloc 179 */ 180 #define __malloc __attribute__((__malloc__)) 181 182 /* 183 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute 184 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute 185 */ 186 #define __mode(x) __attribute__((__mode__(x))) 187 188 /* 189 * Optional: only supported since gcc >= 7 190 * 191 * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 192 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers 193 */ 194 #if __has_attribute(__no_caller_saved_registers__) 195 # define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__)) 196 #else 197 # define __no_caller_saved_registers 198 #endif 199 200 /* 201 * Optional: not supported by clang 202 * 203 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute 204 */ 205 #if __has_attribute(__noclone__) 206 # define __noclone __attribute__((__noclone__)) 207 #else 208 # define __noclone 209 #endif 210 211 /* 212 * Add the pseudo keyword 'fallthrough' so case statement blocks 213 * must end with any of these keywords: 214 * break; 215 * fallthrough; 216 * continue; 217 * goto <label>; 218 * return [expression]; 219 * 220 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes 221 */ 222 #if __has_attribute(__fallthrough__) 223 # define fallthrough __attribute__((__fallthrough__)) 224 #else 225 # define fallthrough do {} while (0) /* fallthrough */ 226 #endif 227 228 /* 229 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes 230 * clang: https://clang.llvm.org/docs/AttributeReference.html#flatten 231 */ 232 # define __flatten __attribute__((flatten)) 233 234 /* 235 * Note the missing underscores. 236 * 237 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute 238 * clang: mentioned 239 */ 240 #define noinline __attribute__((__noinline__)) 241 242 /* 243 * Optional: only supported since gcc >= 8 244 * Optional: not supported by clang 245 * Optional: not supported by icc 246 * 247 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute 248 */ 249 #if __has_attribute(__nonstring__) 250 # define __nonstring __attribute__((__nonstring__)) 251 #else 252 # define __nonstring 253 #endif 254 255 /* 256 * Optional: only supported since GCC >= 7.1, clang >= 13.0. 257 * 258 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute 259 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function 260 */ 261 #if __has_attribute(__no_profile_instrument_function__) 262 # define __no_profile __attribute__((__no_profile_instrument_function__)) 263 #else 264 # define __no_profile 265 #endif 266 267 /* 268 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute 269 * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn 270 * clang: https://clang.llvm.org/docs/AttributeReference.html#id1 271 */ 272 #define __noreturn __attribute__((__noreturn__)) 273 274 /* 275 * Optional: not supported by gcc. 276 * Optional: not supported by icc. 277 * 278 * clang: https://clang.llvm.org/docs/AttributeReference.html#overloadable 279 */ 280 #if __has_attribute(__overloadable__) 281 # define __overloadable __attribute__((__overloadable__)) 282 #else 283 # define __overloadable 284 #endif 285 286 /* 287 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute 288 * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute 289 */ 290 #define __packed __attribute__((__packed__)) 291 292 /* 293 * Note: the "type" argument should match any __builtin_object_size(p, type) usage. 294 * 295 * Optional: not supported by gcc. 296 * Optional: not supported by icc. 297 * 298 * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size 299 */ 300 #if __has_attribute(__pass_object_size__) 301 # define __pass_object_size(type) __attribute__((__pass_object_size__(type))) 302 #else 303 # define __pass_object_size(type) 304 #endif 305 306 /* 307 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute 308 */ 309 #define __pure __attribute__((__pure__)) 310 311 /* 312 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute 313 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute 314 * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate 315 */ 316 #define __section(section) __attribute__((__section__(section))) 317 318 /* 319 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute 320 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute 321 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute 322 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute 323 * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused 324 */ 325 #define __always_unused __attribute__((__unused__)) 326 #define __maybe_unused __attribute__((__unused__)) 327 328 /* 329 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute 330 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute 331 */ 332 #define __used __attribute__((__used__)) 333 334 /* 335 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute 336 * clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result 337 */ 338 #define __must_check __attribute__((__warn_unused_result__)) 339 340 /* 341 * Optional: only supported since clang >= 14.0 342 * 343 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute 344 */ 345 #if __has_attribute(__warning__) 346 # define __compiletime_warning(msg) __attribute__((__warning__(msg))) 347 #else 348 # define __compiletime_warning(msg) 349 #endif 350 351 /* 352 * Optional: only supported since clang >= 14.0 353 * 354 * clang: https://clang.llvm.org/docs/AttributeReference.html#disable-sanitizer-instrumentation 355 * 356 * disable_sanitizer_instrumentation is not always similar to 357 * no_sanitize((<sanitizer-name>)): the latter may still let specific sanitizers 358 * insert code into functions to prevent false positives. Unlike that, 359 * disable_sanitizer_instrumentation prevents all kinds of instrumentation to 360 * functions with the attribute. 361 */ 362 #if __has_attribute(disable_sanitizer_instrumentation) 363 # define __disable_sanitizer_instrumentation \ 364 __attribute__((disable_sanitizer_instrumentation)) 365 #else 366 # define __disable_sanitizer_instrumentation 367 #endif 368 369 /* 370 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute 371 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute 372 */ 373 #define __weak __attribute__((__weak__)) 374 375 /* 376 * Used by functions that use '__builtin_return_address'. These function 377 * don't want to be splited or made inline, which can make 378 * the '__builtin_return_address' get unexpected address. 379 */ 380 #define __fix_address noinline __noclone 381 382 #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ 383