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>

1 files changed, 8 insertions, 12 deletions

diff --git a/arch/sparc/lib/atomic_64.S b/arch/sparc/lib/atomic_64.S
index 0268210ca168..703c9c3935b7 100644
--- a/arch/sparc/lib/atomic_64.S
+++ b/arch/sparc/lib/atomic_64.S
@@ -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