diff options
| author | David Rientjes <rientjes@google.com> | 2007-05-09 02:35:27 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-09 12:30:56 -0700 |
| commit | 0d7ebbbc6eaa5539f78ab20ed6ff1725a4e332ef (patch) | |
| tree | ddef8183ac6440e96678fd4d1159ee86619e2a97 /include/linux | |
| parent | f7e4217b007d1f73e7e3cf10ba4fea4a608c603f (diff) | |
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')
| -rw-r--r-- | include/linux/compiler-gcc.h | 1 | ||||
| -rw-r--r-- | include/linux/compiler-gcc3.h | 6 | ||||
| -rw-r--r-- | include/linux/compiler-gcc4.h | 3 | ||||
| -rw-r--r-- | include/linux/compiler.h | 21 |
4 files changed, 25 insertions, 6 deletions
diff --git a/include/linux/compiler-gcc.h b/include/linux/compiler-gcc.h index a9f794716a81..03ec2311fb29 100644 --- a/include/linux/compiler-gcc.h +++ b/include/linux/compiler-gcc.h @@ -40,3 +40,4 @@ #define noinline __attribute__((noinline)) #define __attribute_pure__ __attribute__((pure)) #define __attribute_const__ __attribute__((__const__)) +#define __maybe_unused __attribute__((unused)) diff --git a/include/linux/compiler-gcc3.h b/include/linux/compiler-gcc3.h index ecd621fd27d2..a9e2863c2dbf 100644 --- a/include/linux/compiler-gcc3.h +++ b/include/linux/compiler-gcc3.h @@ -4,9 +4,11 @@ #include <linux/compiler-gcc.h> #if __GNUC_MINOR__ >= 3 -# define __attribute_used__ __attribute__((__used__)) +# define __used __attribute__((__used__)) +# define __attribute_used__ __used /* deprecated */ #else -# define __attribute_used__ __attribute__((__unused__)) +# define __used __attribute__((__unused__)) +# define __attribute_used__ __used /* deprecated */ #endif #if __GNUC_MINOR__ >= 4 diff --git a/include/linux/compiler-gcc4.h b/include/linux/compiler-gcc4.h index fd0cc7c4a636..a03e9398a6c2 100644 --- a/include/linux/compiler-gcc4.h +++ b/include/linux/compiler-gcc4.h @@ -12,7 +12,8 @@ # define __inline __inline __attribute__((always_inline)) #endif -#define __attribute_used__ __attribute__((__used__)) +#define __used __attribute__((__used__)) +#define __attribute_used__ __used /* deprecated */ #define __must_check __attribute__((warn_unused_result)) #define __compiler_offsetof(a,b) __builtin_offsetof(a,b) #define __always_inline inline __attribute__((always_inline)) 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 /* |