| 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 | * 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 | |
| 79 | /* |
| 80 | * Optional: only supported since gcc >= 9 |
| 81 | * Optional: not supported by clang |
| 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 | |
| 91 | /* |
| 92 | * Optional: not supported by gcc |
| 93 | * Optional: only supported since clang >= 14.0 |
| 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 | |
| 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 | /* |
| 116 | * Optional: not supported by clang |
| 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 | |
| 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 | |
| 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 |
| 163 | * clang: https://clang.llvm.org/docs/AttributeReference.html#malloc |
| 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 | |
| 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 | |
| 185 | /* |
| 186 | * Optional: not supported by clang |
| 187 | * |
| 188 | * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute |
| 189 | */ |
| 190 | #if __has_attribute(__noclone__) |
| 191 | # define __noclone __attribute__((__noclone__)) |
| 192 | #else |
| 193 | # define __noclone |
| 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; |
| 201 | * continue; |
| 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 */ |
| 211 | #endif |
| 212 | |
| 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 | |
| 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 | |
| 227 | /* |
| 228 | * Optional: only supported since gcc >= 8 |
| 229 | * Optional: not supported by clang |
| 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 | |
| 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 | |
| 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 | |
| 258 | /* |
| 259 | * Optional: not supported by gcc. |
| 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 | |
| 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 | |
| 275 | /* |
| 276 | * Note: the "type" argument should match any __builtin_object_size(p, type) usage. |
| 277 | * |
| 278 | * Optional: not supported by gcc. |
| 279 | * |
| 280 | * clang: https://clang.llvm.org/docs/AttributeReference.html#pass-object-size-pass-dynamic-object-size |
| 281 | */ |
| 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 |
| 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 | |
| 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 | */ |
| 303 | #define __section(section) __attribute__((__section__(section))) |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 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 | |
| 369 | #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ |