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b2441318 | 1 | /* SPDX-License-Identifier: GPL-2.0 */ |
bc6245e5 IA |
2 | #ifndef _LINUX_BUILD_BUG_H |
3 | #define _LINUX_BUILD_BUG_H | |
4 | ||
5 | #include <linux/compiler.h> | |
6 | ||
7 | #ifdef __CHECKER__ | |
8 | #define __BUILD_BUG_ON_NOT_POWER_OF_2(n) (0) | |
9 | #define BUILD_BUG_ON_NOT_POWER_OF_2(n) (0) | |
10 | #define BUILD_BUG_ON_ZERO(e) (0) | |
11 | #define BUILD_BUG_ON_NULL(e) ((void *)0) | |
12 | #define BUILD_BUG_ON_INVALID(e) (0) | |
13 | #define BUILD_BUG_ON_MSG(cond, msg) (0) | |
14 | #define BUILD_BUG_ON(condition) (0) | |
15 | #define BUILD_BUG() (0) | |
16 | #else /* __CHECKER__ */ | |
17 | ||
18 | /* Force a compilation error if a constant expression is not a power of 2 */ | |
19 | #define __BUILD_BUG_ON_NOT_POWER_OF_2(n) \ | |
20 | BUILD_BUG_ON(((n) & ((n) - 1)) != 0) | |
21 | #define BUILD_BUG_ON_NOT_POWER_OF_2(n) \ | |
22 | BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0)) | |
23 | ||
24 | /* | |
25 | * Force a compilation error if condition is true, but also produce a | |
26 | * result (of value 0 and type size_t), so the expression can be used | |
27 | * e.g. in a structure initializer (or where-ever else comma expressions | |
28 | * aren't permitted). | |
29 | */ | |
30 | #define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:(-!!(e)); })) | |
31 | #define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:(-!!(e)); })) | |
32 | ||
33 | /* | |
34 | * BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the | |
35 | * expression but avoids the generation of any code, even if that expression | |
36 | * has side-effects. | |
37 | */ | |
38 | #define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e)))) | |
39 | ||
40 | /** | |
41 | * BUILD_BUG_ON_MSG - break compile if a condition is true & emit supplied | |
42 | * error message. | |
43 | * @condition: the condition which the compiler should know is false. | |
44 | * | |
45 | * See BUILD_BUG_ON for description. | |
46 | */ | |
47 | #define BUILD_BUG_ON_MSG(cond, msg) compiletime_assert(!(cond), msg) | |
48 | ||
49 | /** | |
50 | * BUILD_BUG_ON - break compile if a condition is true. | |
51 | * @condition: the condition which the compiler should know is false. | |
52 | * | |
53 | * If you have some code which relies on certain constants being equal, or | |
54 | * some other compile-time-evaluated condition, you should use BUILD_BUG_ON to | |
55 | * detect if someone changes it. | |
56 | * | |
57 | * The implementation uses gcc's reluctance to create a negative array, but gcc | |
58 | * (as of 4.4) only emits that error for obvious cases (e.g. not arguments to | |
59 | * inline functions). Luckily, in 4.3 they added the "error" function | |
60 | * attribute just for this type of case. Thus, we use a negative sized array | |
61 | * (should always create an error on gcc versions older than 4.4) and then call | |
62 | * an undefined function with the error attribute (should always create an | |
63 | * error on gcc 4.3 and later). If for some reason, neither creates a | |
64 | * compile-time error, we'll still have a link-time error, which is harder to | |
65 | * track down. | |
66 | */ | |
67 | #ifndef __OPTIMIZE__ | |
68 | #define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)])) | |
69 | #else | |
70 | #define BUILD_BUG_ON(condition) \ | |
71 | BUILD_BUG_ON_MSG(condition, "BUILD_BUG_ON failed: " #condition) | |
72 | #endif | |
73 | ||
74 | /** | |
75 | * BUILD_BUG - break compile if used. | |
76 | * | |
77 | * If you have some code that you expect the compiler to eliminate at | |
78 | * build time, you should use BUILD_BUG to detect if it is | |
79 | * unexpectedly used. | |
80 | */ | |
81 | #define BUILD_BUG() BUILD_BUG_ON_MSG(1, "BUILD_BUG failed") | |
82 | ||
83 | #endif /* __CHECKER__ */ | |
84 | ||
85 | #endif /* _LINUX_BUILD_BUG_H */ |