diff options
| author | Jan Beulich <JBeulich@suse.com> | 2012-09-10 12:04:16 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2012-09-13 17:43:58 +0200 |
| commit | 1edfbb4153bd29bcf8d2236676238d5237972be1 (patch) | |
| tree | 2c1e7fdf7f0d25adf12e6b334194dcbd2c6e3e56 /arch/x86/include/asm/bitops.h | |
| parent | 6eebdda35e6b18d0dddb2a44e34211bd94f0cad6 (diff) | |
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 <jbeulich@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/504DE550020000780009A258@nat28.tlf.novell.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/include/asm/bitops.h')
| -rw-r--r-- | 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 72f5009deb5a..ebaee695394e 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; |