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: users of __always_inline currently do not write "inline" themselves, 38 * which seems to be required by gcc to apply the attribute according 39 * to its docs (and also "warning: always_inline function might not be 40 * inlinable [-Wattributes]" is emitted). 41 * 42 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute 43 * clang: mentioned 44 */ 45 #define __always_inline inline __attribute__((__always_inline__)) 46 47 /* 48 * The second argument is optional (default 0), so we use a variadic macro 49 * to make the shorthand. 50 * 51 * Beware: Do not apply this to functions which may return 52 * ERR_PTRs. Also, it is probably unwise to apply it to functions 53 * returning extra information in the low bits (but in that case the 54 * compiler should see some alignment anyway, when the return value is 55 * massaged by 'flags = ptr & 3; ptr &= ~3;'). 56 * 57 * Optional: not supported by icc 58 * 59 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute 60 * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned 61 */ 62 #if __has_attribute(__assume_aligned__) 63 # define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) 64 #else 65 # define __assume_aligned(a, ...) 66 #endif 67 68 /* 69 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute 70 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute 71 */ 72 #define __cold __attribute__((__cold__)) 73 74 /* 75 * Note the long name. 76 * 77 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute 78 */ 79 #define __attribute_const__ __attribute__((__const__)) 80 81 /* 82 * Optional: only supported since gcc >= 9 83 * Optional: not supported by clang 84 * Optional: not supported by icc 85 * 86 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute 87 */ 88 #if __has_attribute(__copy__) 89 # define __copy(symbol) __attribute__((__copy__(symbol))) 90 #else 91 # define __copy(symbol) 92 #endif 93 94 /* 95 * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated' 96 * attribute warnings entirely and for good") for more information. 97 * 98 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute 99 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute 100 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute 101 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute 102 * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated 103 */ 104 #define __deprecated 105 106 /* 107 * Optional: only supported since gcc >= 5.1 108 * Optional: not supported by clang 109 * Optional: not supported by icc 110 * 111 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute 112 */ 113 #if __has_attribute(__designated_init__) 114 # define __designated_init __attribute__((__designated_init__)) 115 #else 116 # define __designated_init 117 #endif 118 119 /* 120 * Optional: only supported since clang >= 14.0 121 * 122 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-error-function-attribute 123 */ 124 #if __has_attribute(__error__) 125 # define __compiletime_error(msg) __attribute__((__error__(msg))) 126 #else 127 # define __compiletime_error(msg) 128 #endif 129 130 /* 131 * Optional: not supported by clang 132 * 133 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute 134 */ 135 #if __has_attribute(__externally_visible__) 136 # define __visible __attribute__((__externally_visible__)) 137 #else 138 # define __visible 139 #endif 140 141 /* 142 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute 143 * clang: https://clang.llvm.org/docs/AttributeReference.html#format 144 */ 145 #define __printf(a, b) __attribute__((__format__(printf, a, b))) 146 #define __scanf(a, b) __attribute__((__format__(scanf, a, b))) 147 148 /* 149 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute 150 * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline 151 */ 152 #define __gnu_inline __attribute__((__gnu_inline__)) 153 154 /* 155 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute 156 */ 157 #define __malloc __attribute__((__malloc__)) 158 159 /* 160 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute 161 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute 162 */ 163 #define __mode(x) __attribute__((__mode__(x))) 164 165 /* 166 * Optional: only supported since gcc >= 7 167 * 168 * gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86 169 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers 170 */ 171 #if __has_attribute(__no_caller_saved_registers__) 172 # define __no_caller_saved_registers __attribute__((__no_caller_saved_registers__)) 173 #else 174 # define __no_caller_saved_registers 175 #endif 176 177 /* 178 * Optional: not supported by clang 179 * 180 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute 181 */ 182 #if __has_attribute(__noclone__) 183 # define __noclone __attribute__((__noclone__)) 184 #else 185 # define __noclone 186 #endif 187 188 /* 189 * Add the pseudo keyword 'fallthrough' so case statement blocks 190 * must end with any of these keywords: 191 * break; 192 * fallthrough; 193 * continue; 194 * goto <label>; 195 * return [expression]; 196 * 197 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes 198 */ 199 #if __has_attribute(__fallthrough__) 200 # define fallthrough __attribute__((__fallthrough__)) 201 #else 202 # define fallthrough do {} while (0) /* fallthrough */ 203 #endif 204 205 /* 206 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#Common-Function-Attributes 207 * clang: https://clang.llvm.org/docs/AttributeReference.html#flatten 208 */ 209 # define __flatten __attribute__((flatten)) 210 211 /* 212 * Note the missing underscores. 213 * 214 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute 215 * clang: mentioned 216 */ 217 #define noinline __attribute__((__noinline__)) 218 219 /* 220 * Optional: only supported since gcc >= 8 221 * Optional: not supported by clang 222 * Optional: not supported by icc 223 * 224 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute 225 */ 226 #if __has_attribute(__nonstring__) 227 # define __nonstring __attribute__((__nonstring__)) 228 #else 229 # define __nonstring 230 #endif 231 232 /* 233 * Optional: only supported since GCC >= 7.1, clang >= 13.0. 234 * 235 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fprofile_005finstrument_005ffunction-function-attribute 236 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-profile-instrument-function 237 */ 238 #if __has_attribute(__no_profile_instrument_function__) 239 # define __no_profile __attribute__((__no_profile_instrument_function__)) 240 #else 241 # define __no_profile 242 #endif 243 244 /* 245 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute 246 * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn 247 * clang: https://clang.llvm.org/docs/AttributeReference.html#id1 248 */ 249 #define __noreturn __attribute__((__noreturn__)) 250 251 /* 252 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute 253 * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute 254 */ 255 #define __packed __attribute__((__packed__)) 256 257 /* 258 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute 259 */ 260 #define __pure __attribute__((__pure__)) 261 262 /* 263 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute 264 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute 265 * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate 266 */ 267 #define __section(section) __attribute__((__section__(section))) 268 269 /* 270 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute 271 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute 272 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute 273 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute 274 * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused 275 */ 276 #define __always_unused __attribute__((__unused__)) 277 #define __maybe_unused __attribute__((__unused__)) 278 279 /* 280 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute 281 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute 282 */ 283 #define __used __attribute__((__used__)) 284 285 /* 286 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warn_005funused_005fresult-function-attribute 287 * clang: https://clang.llvm.org/docs/AttributeReference.html#nodiscard-warn-unused-result 288 */ 289 #define __must_check __attribute__((__warn_unused_result__)) 290 291 /* 292 * Optional: only supported since clang >= 14.0 293 * 294 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-warning-function-attribute 295 */ 296 #if __has_attribute(__warning__) 297 # define __compiletime_warning(msg) __attribute__((__warning__(msg))) 298 #else 299 # define __compiletime_warning(msg) 300 #endif 301 302 /* 303 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute 304 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute 305 */ 306 #define __weak __attribute__((__weak__)) 307 308 #endif /* __LINUX_COMPILER_ATTRIBUTES_H */ 309
