linux/arch/powerpc/lib/memcmp_32.S

/* SPDX-License-Identifier: GPL-2.0 */

/*
 * memcmp for PowerPC32
 *
 * Copyright (C) 1996 Paul Mackerras.
 *
 */

#include <asm/ppc_asm.h>
#include <asm/export.h>

	.text

_GLOBAL(memcmp)
	srawi.	r7, r5, 2		/* Divide len by 4 */
	mr	r6, r3
	beq-	3f
	mtctr	r7
	li	r7, 0
1:	lwzx	r3, r6, r7
	lwzx	r0, r4, r7
	addi	r7, r7, 4
	cmplw	cr0, r3, r0
	bdnzt	eq, 1b
	bne	5f
3:	andi.	r3, r5, 3
	beqlr
	cmplwi	cr1, r3, 2
	blt-	cr1, 4f
	lhzx	r3, r6, r7
	lhzx	r0, r4, r7
	addi	r7, r7, 2
	subf.	r3, r0, r3
	beqlr	cr1
	bnelr
4:	lbzx	r3, r6, r7
	lbzx	r0, r4, r7
	subf.	r3, r0, r3
	blr
5:	li	r3, 1
	bgtlr
	li	r3, -1
	blr
EXPORT_SYMBOL(memcmp)
powerpc/lib: optimise PPC32 memcmp At the time being, memcmp() compares two chunks of memory byte per byte. This patch optimises the comparison by comparing word by word. On the same way as commit 15c2d45d17418 ("powerpc: Add 64bit optimised memcmp"), this patch moves memcmp() into a dedicated file named memcmp_32.S A small benchmark performed on an 8xx comparing two chuncks of 512 bytes performed 100000 times gives: Before : 5852274 TB ticks After: 1488638 TB ticks This is almost 4 times faster Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> 2018-05-30 15:06:15 +08:00			`/* SPDX-License-Identifier: GPL-2.0 */`

			`/*`
			`* memcmp for PowerPC32`
			`*`
			`* Copyright (C) 1996 Paul Mackerras.`
			`*`
			`*/`

			`#include <asm/ppc_asm.h>`
			`#include <asm/export.h>`

			`.text`

			`_GLOBAL(memcmp)`
			`srawi. r7, r5, 2 /* Divide len by 4 */`
			`mr r6, r3`
			`beq- 3f`
			`mtctr r7`
			`li r7, 0`
			`1: lwzx r3, r6, r7`
			`lwzx r0, r4, r7`
			`addi r7, r7, 4`
			`cmplw cr0, r3, r0`
			`bdnzt eq, 1b`
			`bne 5f`
			`3: andi. r3, r5, 3`
			`beqlr`
			`cmplwi cr1, r3, 2`
			`blt- cr1, 4f`
			`lhzx r3, r6, r7`
			`lhzx r0, r4, r7`
			`addi r7, r7, 2`
			`subf. r3, r0, r3`
			`beqlr cr1`
			`bnelr`
			`4: lbzx r3, r6, r7`
			`lbzx r0, r4, r7`
			`subf. r3, r0, r3`
			`blr`
			`5: li r3, 1`
			`bgtlr`
			`li r3, -1`
			`blr`
			`EXPORT_SYMBOL(memcmp)`