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memcmp optimized for i686.
This commit is contained in:
Ulrich Drepper
parent
c655f8f851
commit
221c6b37b5
392
sysdeps/i386/i686/memcmp.S
Normal file
392
sysdeps/i386/i686/memcmp.S
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@ -0,0 +1,392 @@
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/* Compare two memory blocks for differences in the first COUNT bytes.
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Copyright (C) 2004 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, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA. */
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#include <sysdep.h>
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#include "asm-syntax.h"
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#include "bp-sym.h"
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#include "bp-asm.h"
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#define PARMS LINKAGE+4 /* Preserve EBX. */
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#define BLK1 PARMS
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#define BLK2 BLK1+PTR_SIZE
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#define LEN BLK2+PTR_SIZE
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#define ENTRANCE pushl %ebx; ENTER
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#define RETURN popl %ebx; LEAVE; ret
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/* Load an entry in a jump table into EBX. TABLE is a jump table
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with relative offsets. INDEX is a register contains the index
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into the jump table. */
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#define LOAD_JUMP_TABLE_ENTRY(TABLE, INDEX) \
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/* We first load PC into EBX. */ \
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call __i686.get_pc_thunk.bx; \
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/* Get the address of the jump table. */ \
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addl $(TABLE - .), %ebx; \
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/* Get the entry and convert the relative offset to the \
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absolute address. */ \
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addl (%ebx,INDEX,4), %ebx
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#ifdef HAVE_HIDDEN
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.section .gnu.linkonce.t.__i686.get_pc_thunk.bx,"ax",@progbits
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.globl __i686.get_pc_thunk.bx
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.hidden __i686.get_pc_thunk.bx
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#else
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.text
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#endif
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ALIGN (4)
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.type __i686.get_pc_thunk.bx,@function
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__i686.get_pc_thunk.bx:
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movl (%esp), %ebx
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ret
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.text
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ALIGN (4)
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ENTRY (BP_SYM (memcmp))
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ENTRANCE
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movl BLK1(%esp), %eax
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movl BLK2(%esp), %edx
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movl LEN(%esp), %ecx
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cmpl $1, %ecx
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jne L(not_1)
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movzbl (%eax), %ecx /* LEN == 1 */
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cmpb (%edx), %cl
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jne L(neq)
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L(bye):
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xorl %eax, %eax
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RETURN
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L(neq):
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sbbl %eax, %eax
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sbbl $-1, %eax
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RETURN
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L(not_1):
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jl L(bye) /* LEN == 0 */
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pushl %esi
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movl %eax, %esi
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cmpl $32, %ecx;
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jge L(32bytesormore) /* LEN => 32 */
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LOAD_JUMP_TABLE_ENTRY (L(table_32bytes), %ecx)
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addl %ecx, %edx
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addl %ecx, %esi
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jmp *%ebx
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ALIGN (4)
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L(28bytes):
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movl -28(%esi), %eax
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movl -28(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(24bytes):
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movl -24(%esi), %eax
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movl -24(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(20bytes):
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movl -20(%esi), %eax
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movl -20(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(16bytes):
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movl -16(%esi), %eax
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movl -16(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(12bytes):
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movl -12(%esi), %eax
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movl -12(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(8bytes):
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movl -8(%esi), %eax
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movl -8(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(4bytes):
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movl -4(%esi), %eax
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movl -4(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(0bytes):
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popl %esi
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xorl %eax, %eax
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RETURN
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L(29bytes):
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movl -29(%esi), %eax
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movl -29(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(25bytes):
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movl -25(%esi), %eax
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movl -25(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(21bytes):
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movl -21(%esi), %eax
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movl -21(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(17bytes):
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movl -17(%esi), %eax
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movl -17(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(13bytes):
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movl -13(%esi), %eax
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movl -13(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(9bytes):
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movl -9(%esi), %eax
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movl -9(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(5bytes):
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movl -5(%esi), %eax
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movl -5(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(1bytes):
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movzbl -1(%esi), %eax
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cmpb -1(%edx), %al
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jne L(set)
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popl %esi
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xorl %eax, %eax
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RETURN
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L(30bytes):
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movl -30(%esi), %eax
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movl -30(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(26bytes):
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movl -26(%esi), %eax
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movl -26(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(22bytes):
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movl -22(%esi), %eax
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movl -22(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(18bytes):
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movl -18(%esi), %eax
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movl -18(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(14bytes):
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movl -14(%esi), %eax
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movl -14(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(10bytes):
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movl -10(%esi), %eax
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movl -10(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(6bytes):
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movl -6(%esi), %eax
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movl -6(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(2bytes):
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movzwl -2(%esi), %eax
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movzwl -2(%edx), %ecx
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cmpb %cl, %al
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jne L(set)
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cmpl %ecx, %eax
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jne L(set)
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popl %esi
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xorl %eax, %eax
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RETURN
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L(31bytes):
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movl -31(%esi), %eax
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movl -31(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(27bytes):
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movl -27(%esi), %eax
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movl -27(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(23bytes):
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movl -23(%esi), %eax
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movl -23(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(19bytes):
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movl -19(%esi), %eax
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movl -19(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(15bytes):
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movl -15(%esi), %eax
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movl -15(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(11bytes):
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movl -11(%esi), %eax
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movl -11(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(7bytes):
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movl -7(%esi), %eax
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movl -7(%edx), %ecx
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cmpl %ecx, %eax
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jne L(find_diff)
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L(3bytes):
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movzwl -3(%esi), %eax
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movzwl -3(%edx), %ecx
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cmpb %cl, %al
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jne L(set)
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cmpl %ecx, %eax
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jne L(set)
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movzbl -1(%esi), %eax
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cmpb -1(%edx), %al
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jne L(set)
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popl %esi
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xorl %eax, %eax
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RETURN
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ALIGN (4)
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/* ECX >= 32. */
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L(32bytesormore):
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subl $32, %ecx
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movl (%esi), %eax
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cmpl (%edx), %eax
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jne L(load_ecx)
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movl 4(%esi), %eax
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cmpl 4(%edx), %eax
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jne L(load_ecx_4)
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movl 8(%esi), %eax
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cmpl 8(%edx), %eax
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jne L(load_ecx_8)
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movl 12(%esi), %eax
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cmpl 12(%edx), %eax
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jne L(load_ecx_12)
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movl 16(%esi), %eax
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cmpl 16(%edx), %eax
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jne L(load_ecx_16)
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movl 20(%esi), %eax
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cmpl 20(%edx), %eax
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jne L(load_ecx_20)
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movl 24(%esi), %eax
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cmpl 24(%edx), %eax
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jne L(load_ecx_24)
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movl 28(%esi), %eax
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cmpl 28(%edx), %eax
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jne L(load_ecx_28)
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addl $32, %esi
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addl $32, %edx
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cmpl $32, %ecx
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jge L(32bytesormore)
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LOAD_JUMP_TABLE_ENTRY (L(table_32bytes), %ecx)
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addl %ecx, %edx
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addl %ecx, %esi
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jmp *%ebx
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L(load_ecx_28):
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addl $0x4, %edx
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L(load_ecx_24):
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addl $0x4, %edx
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L(load_ecx_20):
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addl $0x4, %edx
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L(load_ecx_16):
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addl $0x4, %edx
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L(load_ecx_12):
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addl $0x4, %edx
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L(load_ecx_8):
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addl $0x4, %edx
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L(load_ecx_4):
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addl $0x4, %edx
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L(load_ecx):
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movl (%edx), %ecx
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L(find_diff):
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cmpb %cl, %al
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jne L(set)
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cmpb %ch, %ah
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jne L(set)
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shrl $16,%eax
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shrl $16,%ecx
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cmpb %cl, %al
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jne L(set)
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/* We get there only if we already know there is a
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difference. */
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cmpl %ecx, %eax
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L(set):
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sbbl %eax, %eax
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sbbl $-1, %eax
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popl %esi
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RETURN
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ALIGN (2)
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L(table_32bytes) :
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.long L(0bytes) - . + 0x0
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.long L(1bytes) - . + 0x4
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.long L(2bytes) - . + 0x8
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.long L(3bytes) - . + 0xc
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.long L(4bytes) - . + 0x10
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.long L(5bytes) - . + 0x14
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.long L(6bytes) - . + 0x18
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.long L(7bytes) - . + 0x1c
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.long L(8bytes) - . + 0x20
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.long L(9bytes) - . + 0x24
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.long L(10bytes) - . + 0x28
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.long L(11bytes) - . + 0x2c
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.long L(12bytes) - . + 0x30
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.long L(13bytes) - . + 0x34
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.long L(14bytes) - . + 0x38
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.long L(15bytes) - . + 0x3c
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.long L(16bytes) - . + 0x40
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.long L(17bytes) - . + 0x44
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.long L(18bytes) - . + 0x48
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.long L(19bytes) - . + 0x4c
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.long L(20bytes) - . + 0x50
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.long L(21bytes) - . + 0x54
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.long L(22bytes) - . + 0x58
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.long L(23bytes) - . + 0x5c
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.long L(24bytes) - . + 0x60
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.long L(25bytes) - . + 0x64
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.long L(26bytes) - . + 0x68
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.long L(27bytes) - . + 0x6c
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.long L(28bytes) - . + 0x70
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.long L(29bytes) - . + 0x74
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.long L(30bytes) - . + 0x78
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.long L(31bytes) - . + 0x7c
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END (BP_SYM (memcmp))
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#undef bcmp
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weak_alias (BP_SYM (memcmp), BP_SYM (bcmp))
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