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 (file)
--- 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