powerpc64: Rewrite strcmp in asm to take advantage of word size
Summary: Optimize strcmp for powerpc64. Data is loaded by double words and cmpb intruction is used to find '\0'. Some performance gain rates between the current and the optimized solution: String size (bytes) Gain rate <=8 0.59% <=16 1.92% 32 3.02% 64 5.60% 128 10.16% 256 18.05% 512 30.18% 1024 42.82% Submitted by: alexandre.yamashita_eldorado.org.br, leonardo.bianconi_eldorado.org.br Differential Revision: https://reviews.freebsd.org/D15220
This commit is contained in:
Justin Hibbits
parent
1dffcf9f2d
commit
89a0487c97
4
lib/libc/powerpc64/string/Makefile.inc
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4
lib/libc/powerpc64/string/Makefile.inc
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# $FreeBSD$
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MDSRCS+= \
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strcmp.S
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207
lib/libc/powerpc64/string/strcmp.S
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207
lib/libc/powerpc64/string/strcmp.S
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/*-
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* Copyright (c) 2018 Instituto de Pesquisas Eldorado
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <machine/asm.h>
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__FBSDID("$FreeBSD$");
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#if 0
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RCSID("$NetBSD: strcmp.S,v 1.0 2018/05/10 12:33:02 alexandre Exp $")
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#endif
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/* Alignment mask. */
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#define STRCMP_MULTI_ALIGNMENT_BYTES 8
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#define STRCMP_MULTI_ALIGNMENT_MASK (STRCMP_MULTI_ALIGNMENT_BYTES - 1)
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ENTRY(strcmp)
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/* Starting alignment even if aligned, avoiding performance
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* degradation for short strings.
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*/
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lbz %r5,0(%r3) /* Load chars. */
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lbz %r6,0(%r4)
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cmpd %r5,%r6 /* Check if chars are different. */
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bne .Lstrcmp_end
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cmpdi %r5,0 /* Check if char is zero. */
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beq .Lstrcmp_end
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/* Checking if addresses can be aligned, otherwise copy by byte */
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xor %r7,%r3,%r4
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andi. %r7,%r7,STRCMP_MULTI_ALIGNMENT_MASK
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bne .Lstrcmp_compare_by_byte_loop
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.Lstrcmp_param1_align_loop:
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lbzu %r5,1(%r3) /* Load chars. */
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lbzu %r6,1(%r4)
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cmpd %r5,%r6 /* Check if chars are different. */
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bne .Lstrcmp_end
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cmpdi %r5,0 /* Check if char is zero. */
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beq .Lstrcmp_end
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andi. %r7,%r3,STRCMP_MULTI_ALIGNMENT_MASK /* Check alignment. */
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bne .Lstrcmp_param1_align_loop
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.Lstrcmp_param1_aligned:
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/* If parameter 2 is aligned compare by qword/word,
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* else compare by byte. */
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andi. %r7,%r4,STRCMP_MULTI_ALIGNMENT_MASK
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beq .Lstrcmp_compare_by_word
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lbz %r5,0(%r3) /* Load chars. */
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lbz %r6,0(%r4)
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cmpd %r5,%r6 /* Check if chars are different. */
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bne+ .Lstrcmp_end
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cmpdi %r5,0 /* Check if char is zero. */
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beq+ .Lstrcmp_end
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.Lstrcmp_compare_by_byte_loop:
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lbzu %r5,1(%r3)
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lbzu %r6,1(%r4)
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cmpdi %r5,0
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beq .Lstrcmp_end
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cmpd %r5,%r6
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beq .Lstrcmp_compare_by_byte_loop
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.Lstrcmp_end:
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_compare_by_word:
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ld %r5,0(%r3) /* Load double words. */
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ld %r6,0(%r4)
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xor %r8,%r8,%r8 /* %r8 <- Zero. */
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xor %r0,%r5,%r6 /* Check if double words are different. */
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cmpb %r7,%r5,%r8 /* Check if double words contain zero. */
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/*
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* If double words are different or contain zero,
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* find what byte is different or contains zero,
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* else load next double words.
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*/
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or. %r9,%r7,%r0
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bne .Lstrcmp_check_zeros_differences
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.Lstrcmp_compare_by_word_loop:
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ldu %r5,8(%r3) /* Load double words. */
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ldu %r6,8(%r4)
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xor %r0,%r5,%r6 /* Check if double words are different. */
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cmpb %r7,%r5,%r8 /* Check if double words contain zero. */
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/*
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* If double words are different or contain zero,
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* find what byte is different or contains zero,
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* else load next double words.
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*/
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or. %r9,%r7,%r0
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beq .Lstrcmp_compare_by_word_loop
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.Lstrcmp_check_zeros_differences:
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/* Find what byte is different or contains zero. */
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/* Check 1st byte. */
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rldicr. %r0,%r9,0,7
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bne .Lstrcmp_found_zero_difference_in_1
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/* Check 2nd byte. */
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rldicr. %r0,%r9,8,7
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bne .Lstrcmp_found_zero_difference_in_2
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/* Check 3rd byte. */
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rldicr. %r0,%r9,16,7
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bne .Lstrcmp_found_zero_difference_in_3
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/* Check 4th byte. */
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rldicr. %r0,%r9,24,7
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bne .Lstrcmp_found_zero_difference_in_4
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/* Check 5th byte. */
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andis. %r0,%r9,0xff00
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bne .Lstrcmp_found_zero_difference_in_5
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/* Check 6th byte. */
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andis. %r0,%r9,0xff
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bne .Lstrcmp_found_zero_difference_in_6
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/* Check 7th byte. */
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andi. %r0,%r9,0xff00
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bne .Lstrcmp_found_zero_difference_in_7
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.Lstrcmp_found_zero_difference_in_8:
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/* 8th byte is different or contains zero. */
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andi. %r5,%r5,0xff
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andi. %r6,%r6,0xff
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_found_zero_difference_in_1:
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/* 1st byte is different or contains zero. */
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lbz %r5,0(%r3)
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lbz %r6,0(%r4)
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_found_zero_difference_in_2:
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/* 2nd byte is different or contains zero. */
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lbz %r5,1(%r3)
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lbz %r6,1(%r4)
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_found_zero_difference_in_3:
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/* 3rd byte is different or contains zero. */
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lbz %r5,2(%r3)
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lbz %r6,2(%r4)
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_found_zero_difference_in_4:
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/* 4th byte is different or contains zero. */
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lbz %r5,3(%r3)
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lbz %r6,3(%r4)
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_found_zero_difference_in_5:
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/* 5th byte is different or contains zero. */
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lbz %r5,4(%r3)
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lbz %r6,4(%r4)
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_found_zero_difference_in_6:
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/* 6th byte is different or contains zero. */
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lbz %r5,5(%r3)
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lbz %r6,5(%r4)
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sub %r3,%r5,%r6
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blr
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.Lstrcmp_found_zero_difference_in_7:
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/* 7th byte is different or contains zero. */
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lbz %r5,6(%r3)
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lbz %r6,6(%r4)
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sub %r3,%r5,%r6
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blr
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END(strcmp)
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.section .note.GNU-stack,"",%progbits
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