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| author | attilio <attilio@FreeBSD.org> | 2012-10-09 14:32:30 +0000 |
|---|---|---|
| committer | attilio <attilio@FreeBSD.org> | 2012-10-09 14:32:30 +0000 |
| commit | 6997194551ffae05d71ea650af49c4551d753a1a (patch) | |
| tree | 18e9f31a3018a88b46e78d76a45d0953dea5276b /sys/sys/cdefs.h | |
| parent | 6a02d06d1d81ffda0499310925ef854fd237f382 (diff) | |
| download | FreeBSD-src-6997194551ffae05d71ea650af49c4551d753a1a.zip FreeBSD-src-6997194551ffae05d71ea650af49c4551d753a1a.tar.gz | |
Add an unified macro to deny ability from the compiler to reorder
instruction loads/stores at its will.
The macro __compiler_membar() is currently supported for both gcc and
clang, but kernel compilation will fail otherwise.
Reviewed by: bde, kib
Discussed with: dim, theraven
MFC after: 2 weeks
Diffstat (limited to 'sys/sys/cdefs.h')
| -rw-r--r-- | sys/sys/cdefs.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/sys/sys/cdefs.h b/sys/sys/cdefs.h index d4c78a9..ad6aefc 100644 --- a/sys/sys/cdefs.h +++ b/sys/sys/cdefs.h @@ -82,6 +82,13 @@ # define __GNUC_VA_LIST_COMPATIBILITY 1 #endif +/* + * Compiler memory barriers, specific to gcc and clang. + */ +#if defined(__GNUC__) +#define __compiler_membar() __asm __volatile(" " : : : "memory") +#endif + #ifndef __INTEL_COMPILER # define __GNUCLIKE_BUILTIN_NEXT_ARG 1 # define __GNUCLIKE_MATH_BUILTIN_RELOPS |
