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>
---
arch/x86/include/asm/bitops.h | 10 ++++------
1 file changed, 4 insertions(+), 6 deletions(-)
--- 3.6-rc5/arch/x86/include/asm/bitops.h
+++ 3.6-rc5-x86_64-bsf-bsr-types/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;
--
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