提交 2676b89e 编写于 作者: C Christophe Leroy 提交者: Michael Ellerman

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 15c2d45d ("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: NChristophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: NMichael Ellerman <mpe@ellerman.id.au>
上级 f36bbf21
......@@ -26,14 +26,14 @@ obj-$(CONFIG_PPC_BOOK3S_64) += copyuser_power7.o copypage_power7.o \
memcpy_power7.o
obj64-y += copypage_64.o copyuser_64.o mem_64.o hweight_64.o \
memcpy_64.o memcmp_64.o pmem.o
memcpy_64.o pmem.o
obj64-$(CONFIG_SMP) += locks.o
obj64-$(CONFIG_ALTIVEC) += vmx-helper.o
obj64-$(CONFIG_KPROBES_SANITY_TEST) += test_emulate_step.o
obj-y += checksum_$(BITS).o checksum_wrappers.o \
string_$(BITS).o
string_$(BITS).o memcmp_$(BITS).o
obj-y += sstep.o ldstfp.o quad.o
obj64-y += quad.o
......
/* 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)
......@@ -54,23 +54,6 @@ _GLOBAL(strncmp)
blr
EXPORT_SYMBOL(strncmp)
#ifdef CONFIG_PPC32
_GLOBAL(memcmp)
PPC_LCMPI 0,r5,0
beq- 2f
mtctr r5
addi r6,r3,-1
addi r4,r4,-1
1: lbzu r3,1(r6)
lbzu r0,1(r4)
subf. r3,r0,r3
bdnzt 2,1b
blr
2: li r3,0
blr
EXPORT_SYMBOL(memcmp)
#endif
_GLOBAL(memchr)
PPC_LCMPI 0,r5,0
beq- 2f
......
Markdown is supported
0% .
You are about to add 0 people to the discussion. Proceed with caution.
先完成此消息的编辑!
想要评论请 注册