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| author | David Rientjes <rientjes@google.com> | 2007-05-09 13:35:27 +0400 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-09 23:30:56 +0400 |
| commit | 0d7ebbbc6eaa5539f78ab20ed6ff1725a4e332ef (patch) | |
| tree | ddef8183ac6440e96678fd4d1159ee86619e2a97 /include/linux/compiler.h | |
| parent | f7e4217b007d1f73e7e3cf10ba4fea4a608c603f (diff) | |
| download | linux-0d7ebbbc6eaa5539f78ab20ed6ff1725a4e332ef.tar.xz | |
compiler: introduce __used and __maybe_unused
__used is defined to be __attribute__((unused)) for all pre-3.3 gcc
compilers to suppress warnings for unused functions because perhaps they
are referenced only in inline assembly. It is defined to be
__attribute__((used)) for gcc 3.3 and later so that the code is still
emitted for such functions.
__maybe_unused is defined to be __attribute__((unused)) for both function
and variable use if it could possibly be unreferenced due to the evaluation
of preprocessor macros. Function prototypes shall be marked with
__maybe_unused if the actual definition of the function is dependant on
preprocessor macros.
No update to compiler-intel.h is necessary because ICC supports both
__attribute__((used)) and __attribute__((unused)) as specified by the gcc
manual.
__attribute_used__ is deprecated and will be removed once all current
code is converted to using __used.
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include/linux/compiler.h')
| -rw-r--r-- | include/linux/compiler.h | 21 |
1 files changed, 18 insertions, 3 deletions
diff --git a/include/linux/compiler.h b/include/linux/compiler.h index 3b6949b41745..498c35920762 100644 --- a/include/linux/compiler.h +++ b/include/linux/compiler.h @@ -108,15 +108,30 @@ extern void __chk_io_ptr(const void __iomem *); * Allow us to avoid 'defined but not used' warnings on functions and data, * as well as force them to be emitted to the assembly file. * - * As of gcc 3.3, static functions that are not marked with attribute((used)) - * may be elided from the assembly file. As of gcc 3.3, static data not so + * As of gcc 3.4, static functions that are not marked with attribute((used)) + * may be elided from the assembly file. As of gcc 3.4, static data not so * marked will not be elided, but this may change in a future gcc version. * + * NOTE: Because distributions shipped with a backported unit-at-a-time + * compiler in gcc 3.3, we must define __used to be __attribute__((used)) + * for gcc >=3.3 instead of 3.4. + * * In prior versions of gcc, such functions and data would be emitted, but * would be warned about except with attribute((unused)). + * + * Mark functions that are referenced only in inline assembly as __used so + * the code is emitted even though it appears to be unreferenced. */ #ifndef __attribute_used__ -# define __attribute_used__ /* unimplemented */ +# define __attribute_used__ /* deprecated */ +#endif + +#ifndef __used +# define __used /* unimplemented */ +#endif + +#ifndef __maybe_unused +# define __maybe_unused /* unimplemented */ #endif /* |