Linux Kernel  3.7.1
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compiler-gcc4.h
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1 #ifndef __LINUX_COMPILER_H
2 #error "Please don't include <linux/compiler-gcc4.h> directly, include <linux/compiler.h> instead."
3 #endif
4 
5 /* GCC 4.1.[01] miscompiles __weak */
6 #ifdef __KERNEL__
7 # if __GNUC_MINOR__ == 1 && __GNUC_PATCHLEVEL__ <= 1
8 # error Your version of gcc miscompiles the __weak directive
9 # endif
10 #endif
11 
12 #define __used __attribute__((__used__))
13 #define __must_check __attribute__((warn_unused_result))
14 #define __compiler_offsetof(a,b) __builtin_offsetof(a,b)
15 
16 #if __GNUC_MINOR__ >= 3
17 /* Mark functions as cold. gcc will assume any path leading to a call
18  to them will be unlikely. This means a lot of manual unlikely()s
19  are unnecessary now for any paths leading to the usual suspects
20  like BUG(), printk(), panic() etc. [but let's keep them for now for
21  older compilers]
22 
23  Early snapshots of gcc 4.3 don't support this and we can't detect this
24  in the preprocessor, but we can live with this because they're unreleased.
25  Maketime probing would be overkill here.
26 
27  gcc also has a __attribute__((__hot__)) to move hot functions into
28  a special section, but I don't see any sense in this right now in
29  the kernel context */
30 #define __cold __attribute__((__cold__))
31 
32 #define __linktime_error(message) __attribute__((__error__(message)))
33 
34 #if __GNUC_MINOR__ >= 5
35 /*
36  * Mark a position in code as unreachable. This can be used to
37  * suppress control flow warnings after asm blocks that transfer
38  * control elsewhere.
39  *
40  * Early snapshots of gcc 4.5 don't support this and we can't detect
41  * this in the preprocessor, but we can live with this because they're
42  * unreleased. Really, we need to have autoconf for the kernel.
43  */
44 #define unreachable() __builtin_unreachable()
45 
46 /* Mark a function definition as prohibited from being cloned. */
47 #define __noclone __attribute__((__noclone__))
48 
49 #endif
50 #endif
51 
52 #if __GNUC_MINOR__ >= 6
53 /*
54  * Tell the optimizer that something else uses this function or variable.
55  */
56 #define __visible __attribute__((externally_visible))
57 #endif
58 
59 #if __GNUC_MINOR__ > 0
60 #define __compiletime_object_size(obj) __builtin_object_size(obj, 0)
61 #endif
62 #if __GNUC_MINOR__ >= 3 && !defined(__CHECKER__)
63 #define __compiletime_warning(message) __attribute__((warning(message)))
64 #define __compiletime_error(message) __attribute__((error(message)))
65 #endif