mirror of
https://sourceware.org/git/glibc.git
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fa7f63d8d6
No bug. This commit does not modify any of the memcmp implementation. It just adds __memcmpeq ifdefs to skip obvious cases where computing the proper 1/-1 required by memcmp is not needed.
413 lines
7.8 KiB
ArmAsm
413 lines
7.8 KiB
ArmAsm
/* memcmp with SSE2
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Copyright (C) 2009-2021 Free Software Foundation, Inc.
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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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<https://www.gnu.org/licenses/>. */
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#include <sysdep.h>
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.text
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ENTRY (memcmp)
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#ifdef __ILP32__
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/* Clear the upper 32 bits. */
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movl %edx, %edx
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#endif
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test %RDX_LP, %RDX_LP
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jz L(finz)
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cmpq $1, %rdx
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jbe L(finr1b)
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subq %rdi, %rsi
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movq %rdx, %r10
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cmpq $32, %r10
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jae L(gt32)
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/* Handle small chunks and last block of less than 32 bytes. */
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L(small):
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testq $1, %r10
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jz L(s2b)
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movzbl (%rdi), %eax
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movzbl (%rdi, %rsi), %edx
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subq $1, %r10
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je L(finz1)
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addq $1, %rdi
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subl %edx, %eax
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jnz L(exit)
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L(s2b):
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testq $2, %r10
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jz L(s4b)
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movzwl (%rdi), %eax
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movzwl (%rdi, %rsi), %edx
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subq $2, %r10
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#ifdef USE_AS_MEMCMPEQ
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je L(finz1)
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#else
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je L(fin2_7)
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#endif
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addq $2, %rdi
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cmpl %edx, %eax
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#ifdef USE_AS_MEMCMPEQ
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jnz L(neq_early)
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#else
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jnz L(fin2_7)
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#endif
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L(s4b):
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testq $4, %r10
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jz L(s8b)
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movl (%rdi), %eax
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movl (%rdi, %rsi), %edx
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subq $4, %r10
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#ifdef USE_AS_MEMCMPEQ
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je L(finz1)
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#else
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je L(fin2_7)
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#endif
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addq $4, %rdi
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cmpl %edx, %eax
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#ifdef USE_AS_MEMCMPEQ
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jnz L(neq_early)
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#else
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jnz L(fin2_7)
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#endif
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L(s8b):
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testq $8, %r10
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jz L(s16b)
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movq (%rdi), %rax
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movq (%rdi, %rsi), %rdx
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subq $8, %r10
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#ifdef USE_AS_MEMCMPEQ
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je L(sub_return8)
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#else
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je L(fin2_7)
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#endif
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addq $8, %rdi
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cmpq %rdx, %rax
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#ifdef USE_AS_MEMCMPEQ
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jnz L(neq_early)
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#else
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jnz L(fin2_7)
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#endif
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L(s16b):
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movdqu (%rdi), %xmm1
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movdqu (%rdi, %rsi), %xmm0
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pcmpeqb %xmm0, %xmm1
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#ifdef USE_AS_MEMCMPEQ
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pmovmskb %xmm1, %eax
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subl $0xffff, %eax
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ret
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#else
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pmovmskb %xmm1, %edx
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xorl %eax, %eax
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subl $0xffff, %edx
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jz L(finz)
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bsfl %edx, %ecx
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leaq (%rdi, %rcx), %rcx
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movzbl (%rcx), %eax
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movzbl (%rsi, %rcx), %edx
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jmp L(finz1)
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#endif
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.p2align 4,, 4
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L(finr1b):
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movzbl (%rdi), %eax
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movzbl (%rsi), %edx
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L(finz1):
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subl %edx, %eax
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L(exit):
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ret
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#ifdef USE_AS_MEMCMPEQ
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.p2align 4,, 4
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L(sub_return8):
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subq %rdx, %rax
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movl %eax, %edx
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shrq $32, %rax
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orl %edx, %eax
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ret
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#else
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.p2align 4,, 4
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L(fin2_7):
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cmpq %rdx, %rax
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jz L(finz)
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movq %rax, %r11
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subq %rdx, %r11
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bsfq %r11, %rcx
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sarq $3, %rcx
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salq $3, %rcx
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sarq %cl, %rax
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movzbl %al, %eax
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sarq %cl, %rdx
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movzbl %dl, %edx
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subl %edx, %eax
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ret
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#endif
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.p2align 4,, 4
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L(finz):
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xorl %eax, %eax
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ret
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#ifdef USE_AS_MEMCMPEQ
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.p2align 4,, 4
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L(neq_early):
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movl $1, %eax
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ret
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#endif
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/* For blocks bigger than 32 bytes
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1. Advance one of the addr pointer to be 16B aligned.
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2. Treat the case of both addr pointers aligned to 16B
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separately to avoid movdqu.
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3. Handle any blocks of greater than 64 consecutive bytes with
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unrolling to reduce branches.
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4. At least one addr pointer is 16B aligned, use memory version
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of pcmbeqb.
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*/
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.p2align 4,, 4
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L(gt32):
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movq %rdx, %r11
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addq %rdi, %r11
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movq %rdi, %r8
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andq $15, %r8
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jz L(16am)
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/* Both pointers may be misaligned. */
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movdqu (%rdi), %xmm1
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movdqu (%rdi, %rsi), %xmm0
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pcmpeqb %xmm0, %xmm1
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pmovmskb %xmm1, %edx
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subl $0xffff, %edx
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jnz L(neq)
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neg %r8
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leaq 16(%rdi, %r8), %rdi
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L(16am):
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/* Handle two 16B aligned pointers separately. */
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testq $15, %rsi
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jz L(ATR)
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testq $16, %rdi
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jz L(A32)
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movdqu (%rdi, %rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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L(A32):
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movq %r11, %r10
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andq $-32, %r10
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cmpq %r10, %rdi
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jae L(mt16)
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/* Pre-unroll to be ready for unrolled 64B loop. */
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testq $32, %rdi
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jz L(A64)
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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L(A64):
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movq %r11, %r10
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andq $-64, %r10
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cmpq %r10, %rdi
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jae L(mt32)
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L(A64main):
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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cmpq %rdi, %r10
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jne L(A64main)
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L(mt32):
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movq %r11, %r10
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andq $-32, %r10
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cmpq %r10, %rdi
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jae L(mt16)
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L(A32main):
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqu (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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cmpq %rdi, %r10
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jne L(A32main)
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L(mt16):
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subq %rdi, %r11
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je L(finz)
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movq %r11, %r10
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jmp L(small)
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.p2align 4,, 4
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L(neq):
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#ifdef USE_AS_MEMCMPEQ
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movl $1, %eax
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ret
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#else
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bsfl %edx, %ecx
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movzbl (%rdi, %rcx), %eax
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addq %rdi, %rsi
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movzbl (%rsi,%rcx), %edx
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jmp L(finz1)
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#endif
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.p2align 4,, 4
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L(ATR):
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movq %r11, %r10
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andq $-32, %r10
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cmpq %r10, %rdi
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jae L(mt16)
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testq $16, %rdi
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jz L(ATR32)
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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cmpq %rdi, %r10
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je L(mt16)
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L(ATR32):
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movq %r11, %r10
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andq $-64, %r10
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testq $32, %rdi
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jz L(ATR64)
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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L(ATR64):
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cmpq %rdi, %r10
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je L(mt32)
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L(ATR64main):
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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cmpq %rdi, %r10
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jne L(ATR64main)
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movq %r11, %r10
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andq $-32, %r10
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cmpq %r10, %rdi
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jae L(mt16)
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L(ATR32res):
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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movdqa (%rdi,%rsi), %xmm0
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pcmpeqb (%rdi), %xmm0
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pmovmskb %xmm0, %edx
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subl $0xffff, %edx
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jnz L(neq)
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addq $16, %rdi
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cmpq %r10, %rdi
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jne L(ATR32res)
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subq %rdi, %r11
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je L(finz)
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movq %r11, %r10
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jmp L(small)
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/* Align to 16byte to improve instruction fetch. */
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.p2align 4,, 4
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END(memcmp)
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#ifdef USE_AS_MEMCMPEQ
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libc_hidden_def (memcmp)
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#else
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# undef bcmp
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weak_alias (memcmp, bcmp)
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libc_hidden_builtin_def (memcmp)
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#endif
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