Blame sysdeps/x86_64/memchr.S

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/* Copyright (C) 2011-2018 Free Software Foundation, Inc.
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   Contributed by Intel Corporation.
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   This file is part of the GNU C Library.
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   The GNU C Library is free software; you can redistribute it and/or
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   modify it under the terms of the GNU Lesser General Public
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   License as published by the Free Software Foundation; either
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   version 2.1 of the License, or (at your option) any later version.
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   The GNU C Library is distributed in the hope that it will be useful,
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   but WITHOUT ANY WARRANTY; without even the implied warranty of
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   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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   Lesser General Public License for more details.
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   You should have received a copy of the GNU Lesser General Public
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   License along with the GNU C Library; if not, see
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   <http://www.gnu.org/licenses/>.  */
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#include <sysdep.h>
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#ifdef USE_AS_WMEMCHR
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# define MEMCHR		wmemchr
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# define PCMPEQ		pcmpeqd
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#else
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# define MEMCHR		memchr
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# define PCMPEQ		pcmpeqb
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#endif
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/* fast SSE2 version with using pmaxub and 64 byte loop */
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	.text
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ENTRY(MEMCHR)
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	movd	%esi, %xmm1
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	mov	%edi, %ecx
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#ifdef USE_AS_WMEMCHR
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	test	%rdx, %rdx
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	jz	L(return_null)
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	shl	$2, %rdx
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#else
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	punpcklbw %xmm1, %xmm1
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	test	%rdx, %rdx
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	jz	L(return_null)
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	punpcklbw %xmm1, %xmm1
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#endif
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	and	$63, %ecx
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	pshufd	$0, %xmm1, %xmm1
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	cmp	$48, %ecx
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	ja	L(crosscache)
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	movdqu	(%rdi), %xmm0
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	PCMPEQ	%xmm1, %xmm0
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	pmovmskb %xmm0, %eax
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	test	%eax, %eax
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	jnz	L(matches_1)
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	sub	$16, %rdx
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	jbe	L(return_null)
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	add	$16, %rdi
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	and	$15, %ecx
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	and	$-16, %rdi
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	add	%rcx, %rdx
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	sub	$64, %rdx
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	jbe	L(exit_loop)
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	jmp	L(loop_prolog)
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	.p2align 4
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L(crosscache):
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	and	$15, %ecx
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	and	$-16, %rdi
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	movdqa	(%rdi), %xmm0
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	PCMPEQ	%xmm1, %xmm0
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/* Check if there is a match.  */
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	pmovmskb %xmm0, %eax
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/* Remove the leading bytes.  */
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	sar	%cl, %eax
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	test	%eax, %eax
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	je	L(unaligned_no_match)
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/* Check which byte is a match.  */
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	bsf	%eax, %eax
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	sub	%rax, %rdx
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	jbe	L(return_null)
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	add	%rdi, %rax
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	add	%rcx, %rax
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	ret
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	.p2align 4
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L(unaligned_no_match):
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        /* "rcx" is less than 16.  Calculate "rdx + rcx - 16" by using
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	   "rdx - (16 - rcx)" instead of "(rdx + rcx) - 16" to void
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	   possible addition overflow.  */
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	neg	%rcx
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	add	$16, %rcx
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	sub	%rcx, %rdx
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	jbe	L(return_null)
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	add	$16, %rdi
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	sub	$64, %rdx
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	jbe	L(exit_loop)
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	.p2align 4
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L(loop_prolog):
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	movdqa	(%rdi), %xmm0
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	PCMPEQ	%xmm1, %xmm0
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	pmovmskb %xmm0, %eax
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	test	%eax, %eax
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	jnz	L(matches)
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	movdqa	16(%rdi), %xmm2
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	PCMPEQ	%xmm1, %xmm2
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	pmovmskb %xmm2, %eax
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	test	%eax, %eax
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	jnz	L(matches16)
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	movdqa	32(%rdi), %xmm3
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	PCMPEQ	%xmm1, %xmm3
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	pmovmskb %xmm3, %eax
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	test	%eax, %eax
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	jnz	L(matches32)
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	movdqa	48(%rdi), %xmm4
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	PCMPEQ	%xmm1, %xmm4
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	add	$64, %rdi
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	pmovmskb %xmm4, %eax
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	test	%eax, %eax
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	jnz	L(matches0)
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	test	$0x3f, %rdi
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	jz	L(align64_loop)
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	sub	$64, %rdx
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	jbe	L(exit_loop)
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	movdqa	(%rdi), %xmm0
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	PCMPEQ	%xmm1, %xmm0
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	pmovmskb %xmm0, %eax
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	test	%eax, %eax
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	jnz	L(matches)
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	movdqa	16(%rdi), %xmm2
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	PCMPEQ	%xmm1, %xmm2
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	pmovmskb %xmm2, %eax
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	test	%eax, %eax
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	jnz	L(matches16)
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	movdqa	32(%rdi), %xmm3
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	PCMPEQ	%xmm1, %xmm3
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	pmovmskb %xmm3, %eax
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	test	%eax, %eax
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	jnz	L(matches32)
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	movdqa	48(%rdi), %xmm3
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	PCMPEQ	%xmm1, %xmm3
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	pmovmskb %xmm3, %eax
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	add	$64, %rdi
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	test	%eax, %eax
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	jnz	L(matches0)
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	mov	%rdi, %rcx
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	and	$-64, %rdi
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	and	$63, %ecx
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	add	%rcx, %rdx
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	.p2align 4
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L(align64_loop):
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	sub	$64, %rdx
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	jbe	L(exit_loop)
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	movdqa	(%rdi), %xmm0
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	movdqa	16(%rdi), %xmm2
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	movdqa	32(%rdi), %xmm3
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	movdqa	48(%rdi), %xmm4
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	PCMPEQ	%xmm1, %xmm0
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	PCMPEQ	%xmm1, %xmm2
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	PCMPEQ	%xmm1, %xmm3
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	PCMPEQ	%xmm1, %xmm4
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	pmaxub	%xmm0, %xmm3
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	pmaxub	%xmm2, %xmm4
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	pmaxub	%xmm3, %xmm4
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	pmovmskb %xmm4, %eax
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	add	$64, %rdi
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	test	%eax, %eax
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	jz	L(align64_loop)
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	sub	$64, %rdi
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	pmovmskb %xmm0, %eax
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	test	%eax, %eax
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	jnz	L(matches)
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	pmovmskb %xmm2, %eax
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	test	%eax, %eax
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	jnz	L(matches16)
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	movdqa	32(%rdi), %xmm3
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	PCMPEQ	%xmm1, %xmm3
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	PCMPEQ	48(%rdi), %xmm1
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	pmovmskb %xmm3, %eax
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	test	%eax, %eax
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	jnz	L(matches32)
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	pmovmskb %xmm1, %eax
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	bsf	%eax, %eax
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	lea	48(%rdi, %rax), %rax
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	ret
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	.p2align 4
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L(exit_loop):
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	add	$32, %edx
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	jle	L(exit_loop_32)
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	movdqa	(%rdi), %xmm0
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	PCMPEQ	%xmm1, %xmm0
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	pmovmskb %xmm0, %eax
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	test	%eax, %eax
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	jnz	L(matches)
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	movdqa	16(%rdi), %xmm2
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	PCMPEQ	%xmm1, %xmm2
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	pmovmskb %xmm2, %eax
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	test	%eax, %eax
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	jnz	L(matches16)
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	movdqa	32(%rdi), %xmm3
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	PCMPEQ	%xmm1, %xmm3
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	pmovmskb %xmm3, %eax
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	test	%eax, %eax
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	jnz	L(matches32_1)
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	sub	$16, %edx
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	jle	L(return_null)
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	PCMPEQ	48(%rdi), %xmm1
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	pmovmskb %xmm1, %eax
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	test	%eax, %eax
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	jnz	L(matches48_1)
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	xor	%eax, %eax
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	ret
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	.p2align 4
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L(exit_loop_32):
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	add	$32, %edx
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	movdqa	(%rdi), %xmm0
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	PCMPEQ	%xmm1, %xmm0
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	pmovmskb %xmm0, %eax
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	test	%eax, %eax
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	jnz	L(matches_1)
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	sub	$16, %edx
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	jbe	L(return_null)
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	PCMPEQ	16(%rdi), %xmm1
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	pmovmskb %xmm1, %eax
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	test	%eax, %eax
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	jnz	L(matches16_1)
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	xor	%eax, %eax
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	ret
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	.p2align 4
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L(matches0):
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	bsf	%eax, %eax
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	lea	-16(%rax, %rdi), %rax
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	ret
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	.p2align 4
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L(matches):
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	bsf	%eax, %eax
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	add	%rdi, %rax
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	ret
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	.p2align 4
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L(matches16):
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	bsf	%eax, %eax
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	lea	16(%rax, %rdi), %rax
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	ret
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	.p2align 4
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L(matches32):
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	bsf	%eax, %eax
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	lea	32(%rax, %rdi), %rax
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	ret
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	.p2align 4
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L(matches_1):
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	bsf	%eax, %eax
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	sub	%rax, %rdx
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	jbe	L(return_null)
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	add	%rdi, %rax
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	ret
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	.p2align 4
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L(matches16_1):
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	bsf	%eax, %eax
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	sub	%rax, %rdx
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	jbe	L(return_null)
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	lea	16(%rdi, %rax), %rax
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	ret
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	.p2align 4
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L(matches32_1):
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	bsf	%eax, %eax
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	sub	%rax, %rdx
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	jbe	L(return_null)
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	lea	32(%rdi, %rax), %rax
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	ret
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	.p2align 4
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L(matches48_1):
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	bsf	%eax, %eax
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	sub	%rax, %rdx
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	jbe	L(return_null)
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	lea	48(%rdi, %rax), %rax
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	ret
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	.p2align 4
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L(return_null):
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	xor	%eax, %eax
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	ret
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END(MEMCHR)
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#ifndef USE_AS_WMEMCHR
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strong_alias (memchr, __memchr)
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libc_hidden_builtin_def(memchr)
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#endif