include/linux/compiler*.h: define asm_volatile_goto
[sfrench/cifs-2.6.git] / include / linux / compiler_attributes.h
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) -- except those that are optional.
8  *
9  * Any other "attributes" (i.e. those that depend on a configuration option,
10  * on a compiler, on an architecture, on plugins, on other attributes...)
11  * should be defined elsewhere (e.g. compiler_types.h or compiler-*.h).
12  *
13  * This file is meant to be sorted (by actual attribute name,
14  * not by #define identifier). Use the __attribute__((__name__)) syntax
15  * (i.e. with underscores) to avoid future collisions with other macros.
16  * If an attribute is optional, state the reason in the comment.
17  */
18
19 /*
20  * To check for optional attributes, we use __has_attribute, which is supported
21  * on gcc >= 5, clang >= 2.9 and icc >= 17. In the meantime, to support
22  * 4.6 <= gcc < 5, we implement __has_attribute by hand.
23  *
24  * sparse does not support __has_attribute (yet) and defines __GNUC_MINOR__
25  * depending on the compiler used to build it; however, these attributes have
26  * no semantic effects for sparse, so it does not matter. Also note that,
27  * in order to avoid sparse's warnings, even the unsupported ones must be
28  * defined to 0.
29  */
30 #ifndef __has_attribute
31 # define __has_attribute(x) __GCC4_has_attribute_##x
32 # define __GCC4_has_attribute___assume_aligned__      (__GNUC_MINOR__ >= 9)
33 # define __GCC4_has_attribute___designated_init__     0
34 # define __GCC4_has_attribute___externally_visible__  1
35 # define __GCC4_has_attribute___noclone__             1
36 # define __GCC4_has_attribute___optimize__            1
37 # define __GCC4_has_attribute___nonstring__           0
38 # define __GCC4_has_attribute___no_sanitize_address__ (__GNUC_MINOR__ >= 8)
39 #endif
40
41 /*
42  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-alias-function-attribute
43  */
44 #define __alias(symbol)                 __attribute__((__alias__(#symbol)))
45
46 /*
47  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-aligned-function-attribute
48  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-aligned-type-attribute
49  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-aligned-variable-attribute
50  */
51 #define __aligned(x)                    __attribute__((__aligned__(x)))
52 #define __aligned_largest               __attribute__((__aligned__))
53
54 /*
55  * Note: users of __always_inline currently do not write "inline" themselves,
56  * which seems to be required by gcc to apply the attribute according
57  * to its docs (and also "warning: always_inline function might not be
58  * inlinable [-Wattributes]" is emitted).
59  *
60  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-always_005finline-function-attribute
61  * clang: mentioned
62  */
63 #define __always_inline                 inline __attribute__((__always_inline__))
64
65 /*
66  * The second argument is optional (default 0), so we use a variadic macro
67  * to make the shorthand.
68  *
69  * Beware: Do not apply this to functions which may return
70  * ERR_PTRs. Also, it is probably unwise to apply it to functions
71  * returning extra information in the low bits (but in that case the
72  * compiler should see some alignment anyway, when the return value is
73  * massaged by 'flags = ptr & 3; ptr &= ~3;').
74  *
75  * Optional: only supported since gcc >= 4.9
76  * Optional: not supported by icc
77  *
78  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-assume_005faligned-function-attribute
79  * clang: https://clang.llvm.org/docs/AttributeReference.html#assume-aligned
80  */
81 #if __has_attribute(__assume_aligned__)
82 # define __assume_aligned(a, ...)       __attribute__((__assume_aligned__(a, ## __VA_ARGS__)))
83 #else
84 # define __assume_aligned(a, ...)
85 #endif
86
87 /*
88  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-cold-function-attribute
89  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-cold-label-attribute
90  */
91 #define __cold                          __attribute__((__cold__))
92
93 /*
94  * Note the long name.
95  *
96  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-const-function-attribute
97  */
98 #define __attribute_const__             __attribute__((__const__))
99
100 /*
101  * Don't. Just don't. See commit 771c035372a0 ("deprecate the '__deprecated'
102  * attribute warnings entirely and for good") for more information.
103  *
104  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-deprecated-function-attribute
105  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-deprecated-type-attribute
106  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-deprecated-variable-attribute
107  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Enumerator-Attributes.html#index-deprecated-enumerator-attribute
108  * clang: https://clang.llvm.org/docs/AttributeReference.html#deprecated
109  */
110 #define __deprecated
111
112 /*
113  * Optional: only supported since gcc >= 5.1
114  * Optional: not supported by clang
115  * Optional: not supported by icc
116  *
117  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-designated_005finit-type-attribute
118  */
119 #if __has_attribute(__designated_init__)
120 # define __designated_init              __attribute__((__designated_init__))
121 #else
122 # define __designated_init
123 #endif
124
125 /*
126  * Optional: not supported by clang
127  *
128  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-externally_005fvisible-function-attribute
129  */
130 #if __has_attribute(__externally_visible__)
131 # define __visible                      __attribute__((__externally_visible__))
132 #else
133 # define __visible
134 #endif
135
136 /*
137  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-format-function-attribute
138  * clang: https://clang.llvm.org/docs/AttributeReference.html#format
139  */
140 #define __printf(a, b)                  __attribute__((__format__(printf, a, b)))
141 #define __scanf(a, b)                   __attribute__((__format__(scanf, a, b)))
142
143 /*
144  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-gnu_005finline-function-attribute
145  * clang: https://clang.llvm.org/docs/AttributeReference.html#gnu-inline
146  */
147 #define __gnu_inline                    __attribute__((__gnu_inline__))
148
149 /*
150  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-malloc-function-attribute
151  */
152 #define __malloc                        __attribute__((__malloc__))
153
154 /*
155  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-mode-type-attribute
156  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-mode-variable-attribute
157  */
158 #define __mode(x)                       __attribute__((__mode__(x)))
159
160 /*
161  * Optional: not supported by clang
162  * Note: icc does not recognize gcc's no-tracer
163  *
164  *  gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noclone-function-attribute
165  *  gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-optimize-function-attribute
166  */
167 #if __has_attribute(__noclone__)
168 # if __has_attribute(__optimize__)
169 #  define __noclone                     __attribute__((__noclone__, __optimize__("no-tracer")))
170 # else
171 #  define __noclone                     __attribute__((__noclone__))
172 # endif
173 #else
174 # define __noclone
175 #endif
176
177 /*
178  * Note the missing underscores.
179  *
180  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noinline-function-attribute
181  * clang: mentioned
182  */
183 #define   noinline                      __attribute__((__noinline__))
184
185 /*
186  * Optional: only supported since gcc >= 8
187  * Optional: not supported by clang
188  * Optional: not supported by icc
189  *
190  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-nonstring-variable-attribute
191  */
192 #if __has_attribute(__nonstring__)
193 # define __nonstring                    __attribute__((__nonstring__))
194 #else
195 # define __nonstring
196 #endif
197
198 /*
199  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-noreturn-function-attribute
200  * clang: https://clang.llvm.org/docs/AttributeReference.html#noreturn
201  * clang: https://clang.llvm.org/docs/AttributeReference.html#id1
202  */
203 #define __noreturn                      __attribute__((__noreturn__))
204
205 /*
206  * Optional: only supported since gcc >= 4.8
207  * Optional: not supported by icc
208  *
209  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-no_005fsanitize_005faddress-function-attribute
210  * clang: https://clang.llvm.org/docs/AttributeReference.html#no-sanitize-address-no-address-safety-analysis
211  */
212 #if __has_attribute(__no_sanitize_address__)
213 # define __no_sanitize_address          __attribute__((__no_sanitize_address__))
214 #else
215 # define __no_sanitize_address
216 #endif
217
218 /*
219  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-packed-type-attribute
220  * clang: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-packed-variable-attribute
221  */
222 #define __packed                        __attribute__((__packed__))
223
224 /*
225  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-pure-function-attribute
226  */
227 #define __pure                          __attribute__((__pure__))
228
229 /*
230  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-section-function-attribute
231  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-section-variable-attribute
232  * clang: https://clang.llvm.org/docs/AttributeReference.html#section-declspec-allocate
233  */
234 #define __section(S)                    __attribute__((__section__(#S)))
235
236 /*
237  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-unused-function-attribute
238  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Type-Attributes.html#index-unused-type-attribute
239  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-unused-variable-attribute
240  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Label-Attributes.html#index-unused-label-attribute
241  * clang: https://clang.llvm.org/docs/AttributeReference.html#maybe-unused-unused
242  */
243 #define __always_unused                 __attribute__((__unused__))
244 #define __maybe_unused                  __attribute__((__unused__))
245
246 /*
247  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-used-function-attribute
248  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-used-variable-attribute
249  */
250 #define __used                          __attribute__((__used__))
251
252 /*
253  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Function-Attributes.html#index-weak-function-attribute
254  *   gcc: https://gcc.gnu.org/onlinedocs/gcc/Common-Variable-Attributes.html#index-weak-variable-attribute
255  */
256 #define __weak                          __attribute__((__weak__))
257
258 #endif /* __LINUX_COMPILER_ATTRIBUTES_H */