xref: /linux/include/linux/compiler.h (revision 023ff3eee6255390384e050d9daab1490c88edf8)
1 #ifndef __LINUX_COMPILER_H
2 #define __LINUX_COMPILER_H
3 
4 #ifndef __ASSEMBLY__
5 
6 #ifdef __CHECKER__
7 # define __user		__attribute__((noderef, address_space(1)))
8 # define __kernel	/* default address space */
9 # define __safe		__attribute__((safe))
10 # define __force	__attribute__((force))
11 # define __nocast	__attribute__((nocast))
12 # define __iomem	__attribute__((noderef, address_space(2)))
13 # define __acquires(x)	__attribute__((context(x,0,1)))
14 # define __releases(x)	__attribute__((context(x,1,0)))
15 # define __acquire(x)	__context__(x,1)
16 # define __release(x)	__context__(x,-1)
17 # define __cond_lock(x,c)	((c) ? ({ __acquire(x); 1; }) : 0)
18 extern void __chk_user_ptr(const void __user *);
19 extern void __chk_io_ptr(const void __iomem *);
20 #else
21 # define __user
22 # define __kernel
23 # define __safe
24 # define __force
25 # define __nocast
26 # define __iomem
27 # define __chk_user_ptr(x) (void)0
28 # define __chk_io_ptr(x) (void)0
29 # define __builtin_warning(x, y...) (1)
30 # define __acquires(x)
31 # define __releases(x)
32 # define __acquire(x) (void)0
33 # define __release(x) (void)0
34 # define __cond_lock(x,c) (c)
35 #endif
36 
37 #ifdef __KERNEL__
38 
39 #if __GNUC__ > 4
40 #error no compiler-gcc.h file for this gcc version
41 #elif __GNUC__ == 4
42 # include <linux/compiler-gcc4.h>
43 #elif __GNUC__ == 3 && __GNUC_MINOR__ >= 2
44 # include <linux/compiler-gcc3.h>
45 #else
46 # error Sorry, your compiler is too old/not recognized.
47 #endif
48 
49 /* Intel compiler defines __GNUC__. So we will overwrite implementations
50  * coming from above header files here
51  */
52 #ifdef __INTEL_COMPILER
53 # include <linux/compiler-intel.h>
54 #endif
55 
56 /*
57  * Generic compiler-dependent macros required for kernel
58  * build go below this comment. Actual compiler/compiler version
59  * specific implementations come from the above header files
60  */
61 
62 #define likely(x)	__builtin_expect(!!(x), 1)
63 #define unlikely(x)	__builtin_expect(!!(x), 0)
64 
65 /* Optimization barrier */
66 #ifndef barrier
67 # define barrier() __memory_barrier()
68 #endif
69 
70 #ifndef RELOC_HIDE
71 # define RELOC_HIDE(ptr, off)					\
72   ({ unsigned long __ptr;					\
73      __ptr = (unsigned long) (ptr);				\
74     (typeof(ptr)) (__ptr + (off)); })
75 #endif
76 
77 #endif /* __KERNEL__ */
78 
79 #endif /* __ASSEMBLY__ */
80 
81 #ifdef __KERNEL__
82 /*
83  * Allow us to mark functions as 'deprecated' and have gcc emit a nice
84  * warning for each use, in hopes of speeding the functions removal.
85  * Usage is:
86  * 		int __deprecated foo(void)
87  */
88 #ifndef __deprecated
89 # define __deprecated		/* unimplemented */
90 #endif
91 
92 #ifdef MODULE
93 #define __deprecated_for_modules __deprecated
94 #else
95 #define __deprecated_for_modules
96 #endif
97 
98 #ifndef __must_check
99 #define __must_check
100 #endif
101 
102 #ifndef CONFIG_ENABLE_MUST_CHECK
103 #undef __must_check
104 #define __must_check
105 #endif
106 
107 /*
108  * Allow us to avoid 'defined but not used' warnings on functions and data,
109  * as well as force them to be emitted to the assembly file.
110  *
111  * As of gcc 3.4, static functions that are not marked with attribute((used))
112  * may be elided from the assembly file.  As of gcc 3.4, static data not so
113  * marked will not be elided, but this may change in a future gcc version.
114  *
115  * NOTE: Because distributions shipped with a backported unit-at-a-time
116  * compiler in gcc 3.3, we must define __used to be __attribute__((used))
117  * for gcc >=3.3 instead of 3.4.
118  *
119  * In prior versions of gcc, such functions and data would be emitted, but
120  * would be warned about except with attribute((unused)).
121  *
122  * Mark functions that are referenced only in inline assembly as __used so
123  * the code is emitted even though it appears to be unreferenced.
124  */
125 #ifndef __attribute_used__
126 # define __attribute_used__	/* deprecated */
127 #endif
128 
129 #ifndef __used
130 # define __used			/* unimplemented */
131 #endif
132 
133 #ifndef __maybe_unused
134 # define __maybe_unused		/* unimplemented */
135 #endif
136 
137 /*
138  * From the GCC manual:
139  *
140  * Many functions have no effects except the return value and their
141  * return value depends only on the parameters and/or global
142  * variables.  Such a function can be subject to common subexpression
143  * elimination and loop optimization just as an arithmetic operator
144  * would be.
145  * [...]
146  */
147 #ifndef __attribute_pure__
148 # define __attribute_pure__	/* unimplemented */
149 #endif
150 
151 #ifndef noinline
152 #define noinline
153 #endif
154 
155 #ifndef __always_inline
156 #define __always_inline inline
157 #endif
158 
159 #endif /* __KERNEL__ */
160 
161 /*
162  * From the GCC manual:
163  *
164  * Many functions do not examine any values except their arguments,
165  * and have no effects except the return value.  Basically this is
166  * just slightly more strict class than the `pure' attribute above,
167  * since function is not allowed to read global memory.
168  *
169  * Note that a function that has pointer arguments and examines the
170  * data pointed to must _not_ be declared `const'.  Likewise, a
171  * function that calls a non-`const' function usually must not be
172  * `const'.  It does not make sense for a `const' function to return
173  * `void'.
174  */
175 #ifndef __attribute_const__
176 # define __attribute_const__	/* unimplemented */
177 #endif
178 
179 #endif /* __LINUX_COMPILER_H */
180