Commit-ID: e26a44a2d618a491d5c6a2a8aaf66ee03a94739f Gitweb: http://git.kernel.org/tip/e26a44a2d618a491d5c6a2a8aaf66ee03a94739f Author: Jan Beulich <jbeul...@suse.com> AuthorDate: Tue, 18 Sep 2012 12:16:14 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Wed, 19 Sep 2012 17:26:08 +0200
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" <h...@zytor.com> Suggested-by: Linus Torvalds <torva...@linux-foundation.org> Signed-off-by: Jan Beulich <jbeul...@suse.com> Link: http://lkml.kernel.org/r/5058741e020000780009c...@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- 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 b2af664..6dfd019 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
