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[PATCH] ppc64: speedup cmpxchg

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cmpxchg has the following code:

__typeof__(*(ptr)) _o_ = (o);
__typeof__(*(ptr)) _n_ = (n);

Unfortunately it makes gcc 4.0 store and load the variables to the stack.
Eg in atomic_dec_and_test we get:

  stw     r10,112(r1)
  stw     r9,116(r1)
  lwz     r9,112(r1)
  lwz     r0,116(r1)

x86 is just casting the values so do that instead. Also change __xchg*
and __cmpxchg* to take unsigned values, removing a few sign extensions.

Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
This commit is contained in:
Anton Blanchard 2005-09-06 13:05:58 +10:00 committed by Paul Mackerras
parent 4721e2214b
commit b2c0ab17ba
1 changed files with 8 additions and 11 deletions
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19
include/asm-ppc64/system.h
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@ -158,7 +158,7 @@ static inline int __is_processor(unsigned long pv)
* is more like most of the other architectures.
*/
static __inline__ unsigned long
__xchg_u32(volatile int *m, unsigned long val)
__xchg_u32(volatile unsigned int *m, unsigned long val)
{
unsigned long dummy;
@ -200,7 +200,7 @@ __xchg_u64(volatile long *m, unsigned long val)
extern void __xchg_called_with_bad_pointer(void);
static __inline__ unsigned long
__xchg(volatile void *ptr, unsigned long x, int size)
__xchg(volatile void *ptr, unsigned long x, unsigned int size)
{
switch (size) {
case 4:
@ -223,7 +223,7 @@ __xchg(volatile void *ptr, unsigned long x, int size)
#define __HAVE_ARCH_CMPXCHG 1
static __inline__ unsigned long
__cmpxchg_u32(volatile int *p, int old, int new)
__cmpxchg_u32(volatile unsigned int *p, unsigned long old, unsigned long new)
{
unsigned int prev;
@ -271,7 +271,8 @@ __cmpxchg_u64(volatile long *p, unsigned long old, unsigned long new)
extern void __cmpxchg_called_with_bad_pointer(void);
static __inline__ unsigned long
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
__cmpxchg(volatile void *ptr, unsigned long old, unsigned long new,
unsigned int size)
{
switch (size) {
case 4:
@ -283,13 +284,9 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, int size)
return old;
}
#define cmpxchg(ptr,o,n) \
({ \
__typeof__(*(ptr)) _o_ = (o); \
__typeof__(*(ptr)) _n_ = (n); \
(__typeof__(*(ptr))) __cmpxchg((ptr), (unsigned long)_o_, \
(unsigned long)_n_, sizeof(*(ptr))); \
})
#define cmpxchg(ptr,o,n)\
((__typeof__(*(ptr)))__cmpxchg((ptr),(unsigned long)(o),\
(unsigned long)(n),sizeof(*(ptr))))
/*
* We handle most unaligned accesses in hardware. On the other hand