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" <hpa@zytor.com> Suggested-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Jan Beulich <jbeulich@suse.com> Link: http://lkml.kernel.org/r/5058741E020000780009C014@nat28.tlf.novell.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
parent
5870661c09
commit
e26a44a2d6
1 changed files with 2 additions and 17 deletions
|
@ -347,19 +347,6 @@ static int test_bit(int nr, const volatile unsigned long *addr);
|
||||||
? constant_test_bit((nr), (addr)) \
|
? constant_test_bit((nr), (addr)) \
|
||||||
: variable_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
|
* __ffs - find first set bit in word
|
||||||
* @word: The word to search
|
* @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)
|
static inline unsigned long __ffs(unsigned long word)
|
||||||
{
|
{
|
||||||
asm(BSF_PREFIX "bsf %1,%0"
|
asm("rep; bsf %1,%0"
|
||||||
: "=r" (word)
|
: "=r" (word)
|
||||||
: "rm" (word));
|
: "rm" (word));
|
||||||
return word;
|
return word;
|
||||||
|
@ -382,14 +369,12 @@ static inline unsigned long __ffs(unsigned long word)
|
||||||
*/
|
*/
|
||||||
static inline unsigned long ffz(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)
|
||||||
: "r" (~word));
|
: "r" (~word));
|
||||||
return word;
|
return word;
|
||||||
}
|
}
|
||||||
|
|
||||||
#undef BSF_PREFIX
|
|
||||||
|
|
||||||
/*
|
/*
|
||||||
* __fls: find last set bit in word
|
* __fls: find last set bit in word
|
||||||
* @word: The word to search
|
* @word: The word to search
|
||||||
|
|
Loading…
Add table
Reference in a new issue