diff options
| author | Jan Beulich <JBeulich@suse.com> | 2012-09-18 12:16:14 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-09-19 17:26:08 +0200 |
| commit | e26a44a2d618a491d5c6a2a8aaf66ee03a94739f (patch) | |
| tree | d39e22b9059f6386f9cd2cc088651b1d788ac782 /arch/x86 | |
| parent | 5870661c091e827973674cc3469b50c959008c2b (diff) | |
x86: Use REP BSF unconditionally
Make "REP BSF" unconditional, as per the suggestion of hpa
and Linus, this removes the insane BSF_PREFIX conditional
and simplifies the logic.
Suggested-by: "H. Peter Anvin" <hpa@zytor.com>
Suggested-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jan Beulich <jbeulich@suse.com>
Link: http://lkml.kernel.org/r/5058741E020000780009C014@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86')
| -rw-r--r-- | arch/x86/include/asm/bitops.h | 19 |
1 files changed, 2 insertions, 17 deletions
diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index b2af6645ea7..6dfd0195bb5 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -347,19 +347,6 @@ static int test_bit(int nr, const volatile unsigned long *addr); ? constant_test_bit((nr), (addr)) \ : variable_test_bit((nr), (addr))) -#if (defined(CONFIG_X86_GENERIC) || defined(CONFIG_GENERIC_CPU)) \ - && !defined(CONFIG_CC_OPTIMIZE_FOR_SIZE) -/* - * Since BSF and TZCNT have sufficiently similar semantics for the purposes - * for which we use them here, BMI-capable hardware will decode the prefixed - * variant as 'tzcnt ...' and may execute that faster than 'bsf ...', while - * older hardware will ignore the REP prefix and decode it as 'bsf ...'. - */ -# define BSF_PREFIX "rep;" -#else -# define BSF_PREFIX -#endif - /** * __ffs - find first set bit in word * @word: The word to search @@ -368,7 +355,7 @@ static int test_bit(int nr, const volatile unsigned long *addr); */ static inline unsigned long __ffs(unsigned long word) { - asm(BSF_PREFIX "bsf %1,%0" + asm("rep; bsf %1,%0" : "=r" (word) : "rm" (word)); return word; @@ -382,14 +369,12 @@ static inline unsigned long __ffs(unsigned long word) */ static inline unsigned long ffz(unsigned long word) { - asm(BSF_PREFIX "bsf %1,%0" + asm("rep; bsf %1,%0" : "=r" (word) : "r" (~word)); return word; } -#undef BSF_PREFIX - /* * __fls: find last set bit in word * @word: The word to search |