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>
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 @@
* 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 @@
* 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 @@
#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;