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sparc64: simple microoptimizations for atomic functions

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Simple microoptimizations for sparc64 atomic functions:
Save one instruction by using a delay slot.
Use %g1 instead of %g7, because %g1 is written earlier.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Mikulas Patocka 2010-08-18 08:03:37 +00:00 committed by David S. Miller
parent 9b3bb86aca
commit 6ec274750c
1 changed files with 8 additions and 12 deletions
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20
arch/sparc/lib/atomic_64.S
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@ -52,10 +52,9 @@ atomic_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
add %g7, %o0, %g7
sra %g7, 0, %o0
add %g1, %o0, %g1
retl
nop
sra %g1, 0, %o0
2: BACKOFF_SPIN(%o2, %o3, 1b)
.size atomic_add_ret, .-atomic_add_ret
@ -68,10 +67,9 @@ atomic_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
cas [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %icc, 2f
sub %g7, %o0, %g7
sra %g7, 0, %o0
sub %g1, %o0, %g1
retl
nop
sra %g1, 0, %o0
2: BACKOFF_SPIN(%o2, %o3, 1b)
.size atomic_sub_ret, .-atomic_sub_ret
@ -114,10 +112,9 @@ atomic64_add_ret: /* %o0 = increment, %o1 = atomic_ptr */
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
add %g7, %o0, %g7
mov %g7, %o0
retl
nop
retl
add %g1, %o0, %o0
2: BACKOFF_SPIN(%o2, %o3, 1b)
.size atomic64_add_ret, .-atomic64_add_ret
@ -130,9 +127,8 @@ atomic64_sub_ret: /* %o0 = decrement, %o1 = atomic_ptr */
casx [%o1], %g1, %g7
cmp %g1, %g7
bne,pn %xcc, 2f
sub %g7, %o0, %g7
mov %g7, %o0
retl
nop
retl
sub %g1, %o0, %o0
2: BACKOFF_SPIN(%o2, %o3, 1b)
.size atomic64_sub_ret, .-atomic64_sub_ret