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![Christophe Leroy](/assets/img/avatar_default.png)
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 15c2d45d17
("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>
45 lines
625 B
ArmAsm
45 lines
625 B
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* memcmp for PowerPC32
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*
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* Copyright (C) 1996 Paul Mackerras.
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*
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*/
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#include <asm/ppc_asm.h>
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#include <asm/export.h>
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.text
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_GLOBAL(memcmp)
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srawi. r7, r5, 2 /* Divide len by 4 */
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mr r6, r3
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beq- 3f
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mtctr r7
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li r7, 0
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1: lwzx r3, r6, r7
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lwzx r0, r4, r7
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addi r7, r7, 4
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cmplw cr0, r3, r0
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bdnzt eq, 1b
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bne 5f
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3: andi. r3, r5, 3
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beqlr
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cmplwi cr1, r3, 2
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blt- cr1, 4f
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lhzx r3, r6, r7
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lhzx r0, r4, r7
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addi r7, r7, 2
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subf. r3, r0, r3
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beqlr cr1
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bnelr
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4: lbzx r3, r6, r7
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lbzx r0, r4, r7
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subf. r3, r0, r3
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blr
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5: li r3, 1
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bgtlr
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li r3, -1
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blr
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EXPORT_SYMBOL(memcmp)
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