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 * __has_attribute is supported on gcc >= 5, clang >= 2.9 and icc >= 17. 25 * In the meantime, to support 4.6 <= gcc < 5, we implement __has_attribute 26 * by hand. 27 * 28 * sparse does not support __has_attribute (yet) and defines __GNUC_MINOR__ 29 * depending on the compiler used to build it; however, these attributes have 30 * no semantic effects for sparse, so it does not matter. Also note that, 31 * in order to avoid sparse's warnings, even the unsupported ones must be 32 * defined to 0. 33 */ 34#ifndef __has_attribute 35# define __has_attribute(x) __GCC4_has_attribute_##x 36# define __GCC4_has_attribute___assume_aligned__ (__GNUC_MINOR__ >= 9) 37# define __GCC4_has_attribute___copy__ 0 38# define __GCC4_has_attribute___designated_init__ 0 39# define __GCC4_has_attribute___externally_visible__ 1 40# define __GCC4_has_attribute___noclone__ 1 41# define __GCC4_has_attribute___nonstring__ 0 42# define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8) 43#endif 44 45/* 46 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute 47 */ 48#define __alias(symbol) __attribute__((__alias__(#symbol))) 49 50/* 51 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute 52 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute 53 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute 54 */ 55#define __aligned(x) __attribute__((__aligned__(x))) 56#define __aligned_largest __attribute__((__aligned__)) 57 58/* 59 * Note: users of __always_inline currently do not write "inline" themselves, 60 * which seems to be required by gcc to apply the attribute according 61 * to its docs (and also "warning: always_inline function might not be 62 * inlinable [-Wattributes]" is emitted). 63 * 64 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute 65 * clang: mentioned 66 */ 67#define __always_inline inline __attribute__((__always_inline__)) 68 69/* 70 * The second argument is optional (default 0), so we use a variadic macro 71 * to make the shorthand. 72 * 73 * Beware: Do not apply this to functions which may return 74 * ERR_PTRs. Also, it is probably unwise to apply it to functions 75 * returning extra information in the low bits (but in that case the 76 * compiler should see some alignment anyway, when the return value is 77 * massaged by 'flags = ptr & 3; ptr &= ~3;'). 78 * 79 * Optional: only supported since gcc >= 4.9 80 * Optional: not supported by icc 81 * 82 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute 83 * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned 84 */ 85#if __has_attribute(__assume_aligned__) 86# define __assume_aligned(a, ...) __attribute__((__assume_aligned__(a, ## __VA_ARGS__))) 87#else 88# define __assume_aligned(a, ...) 89#endif 90 91/* 92 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute 93 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute 94 */ 95#define __cold __attribute__((__cold__)) 96 97/* 98 * Note the long name. 99 * 100 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute 101 */ 102#define __attribute_const__ __attribute__((__const__)) 103 104/* 105 * Optional: only supported since gcc >= 9 106 * Optional: not supported by clang 107 * Optional: not supported by icc 108 * 109 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute 110 */ 111#if __has_attribute(__copy__) 112# define __copy(symbol) __attribute__((__copy__(symbol))) 113#else 114# define __copy(symbol) 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: only supported since gcc >= 5.1 131 * Optional: not supported by clang 132 * Optional: not supported by icc 133 * 134 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute 135 */ 136#if __has_attribute(__designated_init__) 137# define __designated_init __attribute__((__designated_init__)) 138#else 139# define __designated_init 140#endif 141 142/* 143 * Optional: not supported by clang 144 * 145 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute 146 */ 147#if __has_attribute(__externally_visible__) 148# define __visible __attribute__((__externally_visible__)) 149#else 150# define __visible 151#endif 152 153/* 154 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute 155 * clang: https://clang.llvm.org/docs/AttributeReference.html#format 156 */ 157#define __printf(a, b) __attribute__((__format__(printf, a, b))) 158#define __scanf(a, b) __attribute__((__format__(scanf, a, b))) 159 160/* 161 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute 162 * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline 163 */ 164#define __gnu_inline __attribute__((__gnu_inline__)) 165 166/* 167 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute 168 */ 169#define __malloc __attribute__((__malloc__)) 170 171/* 172 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute 173 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute 174 */ 175#define __mode(x) __attribute__((__mode__(x))) 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 * Note the missing underscores. 190 * 191 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute 192 * clang: mentioned 193 */ 194#define noinline __attribute__((__noinline__)) 195 196/* 197 * Optional: only supported since gcc >= 8 198 * Optional: not supported by clang 199 * Optional: not supported by icc 200 * 201 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute 202 */ 203#if __has_attribute(__nonstring__) 204# define __nonstring __attribute__((__nonstring__)) 205#else 206# define __nonstring 207#endif 208 209/* 210 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute 211 * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn 212 * clang: https://clang.llvm.org/docs/AttributeReference.html#id1 213 */ 214#define __noreturn __attribute__((__noreturn__)) 215 216/* 217 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute 218 * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute 219 */ 220#define __packed __attribute__((__packed__)) 221 222/* 223 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute 224 */ 225#define __pure __attribute__((__pure__)) 226 227/* 228 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute 229 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute 230 * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate 231 */ 232#define __section(S) __attribute__((__section__(#S))) 233 234/* 235 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute 236 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute 237 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute 238 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute 239 * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused 240 */ 241#define __always_unused __attribute__((__unused__)) 242#define __maybe_unused __attribute__((__unused__)) 243 244/* 245 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute 246 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute 247 */ 248#define __used __attribute__((__used__)) 249 250/* 251 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute 252 * gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute 253 */ 254#define __weak __attribute__((__weak__)) 255 256#endif /* __LINUX_COMPILER_ATTRIBUTES_H */ 257