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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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2676b89eb8
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>
46 lines
625 B
ArmAsm
46 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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