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84b8bf6d5d
BUILD_BUG_* macros have been defined in several headers. It would be nice to collect them in include/linux/bug.h like Linux. This commit is cherry-picking useful macros from include/linux/bug.h of Linux 4.4. I did not import BUILD_BUG_ON_MSG() because it would not work if it is used with include/common.h in U-Boot. I'd like to postpone it until the root cause (the "error()" macro in include/common.h causes the name conflict with "__attribute__((error()))") is fixed. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Tom Rini <trini@konsulko.com>
56 lines
2.2 KiB
C
56 lines
2.2 KiB
C
#ifndef _LINUX_BUG_H
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#define _LINUX_BUG_H
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#include <linux/compiler.h>
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#ifdef __CHECKER__
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#define BUILD_BUG_ON_NOT_POWER_OF_2(n) (0)
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#define BUILD_BUG_ON_ZERO(e) (0)
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#define BUILD_BUG_ON_NULL(e) ((void*)0)
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#define BUILD_BUG_ON_INVALID(e) (0)
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#define BUILD_BUG_ON(condition) (0)
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#define BUILD_BUG() (0)
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#else /* __CHECKER__ */
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/* Force a compilation error if a constant expression is not a power of 2 */
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#define BUILD_BUG_ON_NOT_POWER_OF_2(n) \
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BUILD_BUG_ON((n) == 0 || (((n) & ((n) - 1)) != 0))
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/* Force a compilation error if condition is true, but also produce a
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result (of value 0 and type size_t), so the expression can be used
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e.g. in a structure initializer (or where-ever else comma expressions
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aren't permitted). */
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#define BUILD_BUG_ON_ZERO(e) (sizeof(struct { int:-!!(e); }))
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#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
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/*
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* BUILD_BUG_ON_INVALID() permits the compiler to check the validity of the
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* expression but avoids the generation of any code, even if that expression
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* has side-effects.
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*/
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#define BUILD_BUG_ON_INVALID(e) ((void)(sizeof((__force long)(e))))
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/**
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* BUILD_BUG_ON - break compile if a condition is true.
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* @condition: the condition which the compiler should know is false.
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*
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* If you have some code which relies on certain constants being equal, or
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* some other compile-time-evaluated condition, you should use BUILD_BUG_ON to
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* detect if someone changes it.
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*
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* The implementation uses gcc's reluctance to create a negative array, but gcc
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* (as of 4.4) only emits that error for obvious cases (e.g. not arguments to
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* inline functions). Luckily, in 4.3 they added the "error" function
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* attribute just for this type of case. Thus, we use a negative sized array
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* (should always create an error on gcc versions older than 4.4) and then call
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* an undefined function with the error attribute (should always create an
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* error on gcc 4.3 and later). If for some reason, neither creates a
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* compile-time error, we'll still have a link-time error, which is harder to
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* track down.
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*/
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#define BUILD_BUG_ON(condition) ((void)sizeof(char[1 - 2*!!(condition)]))
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#endif /* __CHECKER__ */
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#endif /* _LINUX_BUG_H */
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