summaryrefslogtreecommitdiff
path: root/include/linux/compiler_attributes.h
blob: b2a3f4f641a70745d94e6b84acbc2261d8e7a03d (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
/* SPDX-License-Identifier: GPL-2.0 */
#ifndef __LINUX_COMPILER_ATTRIBUTES_H
#define __LINUX_COMPILER_ATTRIBUTES_H

/*
 * The attributes in this file are unconditionally defined and they directly
 * map to compiler attribute(s), unless one of the compilers does not support
 * the attribute. In that case, __has_attribute is used to check for support
 * and the reason is stated in its comment ("Optional: ...").
 *
 * Any other "attributes" (i.e. those that depend on a configuration option,
 * on a compiler, on an architecture, on plugins, on other attributes...)
 * should be defined elsewhere (e.g. compiler_types.h or compiler-*.h).
 * The intention is to keep this file as simple as possible, as well as
 * compiler- and version-agnostic (e.g. avoiding GCC_VERSION checks).
 *
 * This file is meant to be sorted (by actual attribute name,
 * not by #define identifier). Use the __attribute__((__name__)) syntax
 * (i.e. with underscores) to avoid future collisions with other macros.
 * Provide links to the documentation of each supported compiler, if it exists.
 */

/*
 * __has_attribute is supported on gcc >= 5, clang >= 2.9 and icc >= 17.
 * In the meantime, to support gcc < 5, we implement __has_attribute
 * by hand.
 */
#ifndef __has_attribute
# define __has_attribute(x) __GCC4_has_attribute_##x
# define __GCC4_has_attribute___assume_aligned__      (__GNUC_MINOR__ >= 9)
# define __GCC4_has_attribute___copy__                0
# define __GCC4_has_attribute___designated_init__     0
# define __GCC4_has_attribute___externally_visible__  1
# define __GCC4_has_attribute___no_caller_saved_registers__ 0
# define __GCC4_has_attribute___noclone__             1
# define __GCC4_has_attribute___nonstring__           0
# define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
# define __GCC4_has_attribute___no_sanitize_undefined__ (__GNUC_MINOR__ >= 9)
# define __GCC4_has_attribute___fallthrough__         0
#endif

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute
 */
#define __alias(symbol)                 __attribute__((__alias__(#symbol)))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute
 */
#define __aligned(x)                    __attribute__((__aligned__(x)))
#define __aligned_largest               __attribute__((__aligned__))

/*
 * Note: users of __always_inline currently do not write "inline" themselves,
 * which seems to be required by gcc to apply the attribute according
 * to its docs (and also "warning: always_inline function might not be
 * inlinable [-Wattributes]" is emitted).
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute
 * clang: mentioned
 */
#define __always_inline                 inline __attribute__((__always_inline__))

/*
 * The second argument is optional (default 0), so we use a variadic macro
 * to make the shorthand.
 *
 * Beware: Do not apply this to functions which may return
 * ERR_PTRs. Also, it is probably unwise to apply it to functions
 * returning extra information in the low bits (but in that case the
 * compiler should see some alignment anyway, when the return value is
 * massaged by 'flags = ptr & 3; ptr &= ~3;').
 *
 * Optional: only supported since gcc >= 4.9
 * Optional: not supported by icc
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute
 * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned
 */
#if __has_attribute(__assume_aligned__)
# define __assume_aligned(a, ...)       __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
#else
# define __assume_aligned(a, ...)
#endif

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute
 */
#define __cold                          __attribute__((__cold__))

/*
 * Note the long name.
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute
 */
#define __attribute_const__             __attribute__((__const__))

/*
 * Optional: only supported since gcc >= 9
 * Optional: not supported by clang
 * Optional: not supported by icc
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-copy-function-attribute
 */
#if __has_attribute(__copy__)
# define __copy(symbol)                 __attribute__((__copy__(symbol)))
#else
# define __copy(symbol)
#endif

/*
 * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated'
 * attribute warnings entirely and for good") for more information.
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute
 * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated
 */
#define __deprecated

/*
 * Optional: only supported since gcc >= 5.1
 * Optional: not supported by clang
 * Optional: not supported by icc
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute
 */
#if __has_attribute(__designated_init__)
# define __designated_init              __attribute__((__designated_init__))
#else
# define __designated_init
#endif

/*
 * Optional: not supported by clang
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute
 */
#if __has_attribute(__externally_visible__)
# define __visible                      __attribute__((__externally_visible__))
#else
# define __visible
#endif

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute
 * clang: https://clang.llvm.org/docs/AttributeReference.html#format
 */
#define __printf(a, b)                  __attribute__((__format__(printf, a, b)))
#define __scanf(a, b)                   __attribute__((__format__(scanf, a, b)))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute
 * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline
 */
#define __gnu_inline                    __attribute__((__gnu_inline__))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
 */
#define __malloc                        __attribute__((__malloc__))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute
 */
#define __mode(x)                       __attribute__((__mode__(x)))

/*
 * Optional: only supported since gcc >= 7
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/x86-Function-Attributes.html#index-no_005fcaller_005fsaved_005fregisters-function-attribute_002c-x86
 * clang: https://clang.llvm.org/docs/AttributeReference.html#no-caller-saved-registers
 */
#if __has_attribute(__no_caller_saved_registers__)
# define __no_caller_saved_registers	__attribute__((__no_caller_saved_registers__))
#else
# define __no_caller_saved_registers
#endif

/*
 * Optional: not supported by clang
 *
 *  gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute
 */
#if __has_attribute(__noclone__)
# define __noclone                      __attribute__((__noclone__))
#else
# define __noclone
#endif

/*
 * Add the pseudo keyword 'fallthrough' so case statement blocks
 * must end with any of these keywords:
 *   break;
 *   fallthrough;
 *   goto <label>;
 *   return [expression];
 *
 *  gcc: https://gcc.gnu.org/onlinedocs/gcc/Statement-Attributes.html#Statement-Attributes
 */
#if __has_attribute(__fallthrough__)
# define fallthrough                    __attribute__((__fallthrough__))
#else
# define fallthrough                    do {} while (0)  /* fallthrough */
#endif

/*
 * Note the missing underscores.
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute
 * clang: mentioned
 */
#define   noinline                      __attribute__((__noinline__))

/*
 * Optional: only supported since gcc >= 8
 * Optional: not supported by clang
 * Optional: not supported by icc
 *
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute
 */
#if __has_attribute(__nonstring__)
# define __nonstring                    __attribute__((__nonstring__))
#else
# define __nonstring
#endif

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
 * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn
 * clang: https://clang.llvm.org/docs/AttributeReference.html#id1
 */
#define __noreturn                      __attribute__((__noreturn__))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute
 * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute
 */
#define __packed                        __attribute__((__packed__))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute
 */
#define __pure                          __attribute__((__pure__))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute
 * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate
 */
#define __section(section)              __attribute__((__section__(section)))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute
 * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused
 */
#define __always_unused                 __attribute__((__unused__))
#define __maybe_unused                  __attribute__((__unused__))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute
 */
#define __used                          __attribute__((__used__))

/*
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
 *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute
 */
#define __weak                          __attribute__((__weak__))

#endif /* __LINUX_COMPILER_ATTRIBUTES_H */