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Commit 7bf6057b authored by Christophe Leroy's avatar Christophe Leroy Committed by Michael Ellerman
Browse files

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: default avatarChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
parent c0622167

arch/powerpc/lib/copy_32.S

+14 −7
Original line number Diff line number Diff line
@@ -91,17 +91,17 @@ EXPORT_SYMBOL(memset16) 
 * 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 @@ _GLOBAL(memset_nocache_branch) 
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)



/*