Commit-ID: 1edfbb4153bd29bcf8d2236676238d5237972be1 Gitweb: http://git.kernel.org/tip/1edfbb4153bd29bcf8d2236676238d5237972be1 Author: Jan Beulich <jbeul...@suse.com> AuthorDate: Mon, 10 Sep 2012 12:04:16 +0100 Committer: Ingo Molnar <mi...@kernel.org> CommitDate: Thu, 13 Sep 2012 17:43:58 +0200
x86/64: Adjust types of temporaries used by ffs()/fls()/fls64() The 64-bit special cases of the former two (the thrird one is 64-bit only anyway) don't need to use "long" temporaries, as the result will always fit in a 32-bit variable, and the functions return plain "int". This avoids a few REX prefixes, i.e. minimally reduces code size. Signed-off-by: Jan Beulich <jbeul...@suse.com> Cc: Linus Torvalds <torva...@linux-foundation.org> Link: http://lkml.kernel.org/r/504de550020000780009a...@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mi...@kernel.org> --- arch/x86/include/asm/bitops.h | 10 ++++------ 1 files changed, 4 insertions(+), 6 deletions(-) diff --git a/arch/x86/include/asm/bitops.h b/arch/x86/include/asm/bitops.h index 72f5009..ebaee69 100644 --- a/arch/x86/include/asm/bitops.h +++ b/arch/x86/include/asm/bitops.h @@ -417,10 +417,9 @@ static inline int ffs(int x) * We cannot do this on 32 bits because at the very least some * 486 CPUs did not behave this way. */ - long tmp = -1; asm("bsfl %1,%0" : "=r" (r) - : "rm" (x), "0" (tmp)); + : "rm" (x), "0" (-1)); #elif defined(CONFIG_X86_CMOV) asm("bsfl %1,%0\n\t" "cmovzl %2,%0" @@ -459,10 +458,9 @@ static inline int fls(int x) * We cannot do this on 32 bits because at the very least some * 486 CPUs did not behave this way. */ - long tmp = -1; asm("bsrl %1,%0" : "=r" (r) - : "rm" (x), "0" (tmp)); + : "rm" (x), "0" (-1)); #elif defined(CONFIG_X86_CMOV) asm("bsrl %1,%0\n\t" "cmovzl %2,%0" @@ -490,13 +488,13 @@ static inline int fls(int x) #ifdef CONFIG_X86_64 static __always_inline int fls64(__u64 x) { - long bitpos = -1; + int bitpos = -1; /* * AMD64 says BSRQ won't clobber the dest reg if x==0; Intel64 says the * dest reg is undefined if x==0, but their CPU architect says its * value is written to set it to the same as before. */ - asm("bsrq %1,%0" + asm("bsrq %1,%q0" : "+r" (bitpos) : "rm" (x)); return bitpos + 1; -- 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/
