sparc64: simple microoptimizations for atomic functions
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>
diff --git a/arch/sparc/lib/atomic_64.S b/arch/sparc/lib/atomic_64.S
index 0268210..703c9c3 100644
--- a/arch/sparc/lib/atomic_64.S
+++ b/arch/sparc/lib/atomic_64.S
@@ -52,10 +52,9 @@
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 @@
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 @@
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 @@
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