powerpc/32: optimise memset()
There is no need to extend the set value to an int when the length
is lower than 4 as in that case we only do byte stores.
We can therefore immediately branch to the part handling it.
By separating it from the normal case, we are able to eliminate
a few actions on the destination pointer.
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
diff --git a/arch/powerpc/lib/copy_32.S b/arch/powerpc/lib/copy_32.S
index a3ffeac..05aaee2 100644
--- a/arch/powerpc/lib/copy_32.S
+++ b/arch/powerpc/lib/copy_32.S
@@ -91,17 +91,17 @@
* replaced by a nop once cache is active. This is done in machine_init()
*/
_GLOBAL(memset)
+ cmplwi 0,r5,4
+ blt 7f
+
rlwimi r4,r4,8,16,23
rlwimi r4,r4,16,0,15
- addi r6,r3,-4
- cmplwi 0,r5,4
- blt 7f
- stwu r4,4(r6)
+ stw r4,0(r3)
beqlr
- andi. r0,r6,3
+ andi. r0,r3,3
add r5,r0,r5
- subf r6,r0,r6
+ subf r6,r0,r3
cmplwi 0,r4,0
bne 2f /* Use normal procedure if r4 is not zero */
_GLOBAL(memset_nocache_branch)
@@ -132,13 +132,20 @@
1: stwu r4,4(r6)
bdnz 1b
6: andi. r5,r5,3
-7: cmpwi 0,r5,0
beqlr
mtctr r5
addi r6,r6,3
8: stbu r4,1(r6)
bdnz 8b
blr
+
+7: cmpwi 0,r5,0
+ beqlr
+ mtctr r5
+ addi r6,r3,-1
+9: stbu r4,1(r6)
+ bdnz 9b
+ blr
EXPORT_SYMBOL(memset)
/*
