259 lines
5.2 KiB
ArmAsm
259 lines
5.2 KiB
ArmAsm
/* Compare two strings for differences.
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For SPARC v7.
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Copyright (C) 1996-2022 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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/* Normally, this uses ((xword - 0x01010101) & 0x80808080) test
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to find out if any byte in xword could be zero. This is fast, but
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also gives false alarm for any byte in range 0x81-0xff. It does
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not matter for correctness, as if this test tells us there could
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be some zero byte, we check it byte by byte, but if bytes with
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high bits set are common in the strings, then this will give poor
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performance. You can #define EIGHTBIT_NOT_RARE and the algorithm
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will use one tick slower, but more precise test
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((xword - 0x01010101) & (~xword) & 0x80808080),
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which does not give any false alarms (but if some bits are set,
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one cannot assume from it which bytes are zero and which are not).
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It is yet to be measured, what is the correct default for glibc
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in these days for an average user.
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*/
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.text
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.align 4
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ENTRY(strcmp)
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andcc %o0, 3, %g0
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be 13f
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sethi %hi(0x80808080), %g1
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ldub [%o0], %o4
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add %o0, 1, %o0
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ldub [%o1], %o5
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cmp %o4, 0
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add %o1, 1, %o1
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be 2f
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subcc %o4, %o5, %o4
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bne 2f
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andcc %o0, 3, %g0
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be 4f
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or %g1, %lo(0x80808080), %o3
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ldub [%o0], %o4
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add %o0, 1, %o0
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ldub [%o1], %o5
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cmp %o4, 0
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add %o1, 1, %o1
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be 2f
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subcc %o4, %o5, %o4
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bne 2f
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andcc %o0, 3, %g0
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be 5f
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sethi %hi(0x01010101), %g1
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ldub [%o0], %o4
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add %o0, 1, %o0
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ldub [%o1], %o5
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cmp %o4, 0
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add %o1, 1, %o1
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be 2f
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subcc %o4, %o5, %o4
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bne 2f
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andcc %o1, 3, %g2
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bne 12f
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or %g1, %lo(0x01010101), %o2
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b 1f
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ld [%o0], %o4
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2: retl
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mov %o4, %o0
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13: or %g1, %lo(0x80808080), %o3
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4: sethi %hi(0x01010101), %g1
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5: andcc %o1, 3, %g2
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bne 12f
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or %g1, %lo(0x01010101), %o2
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0: ld [%o0], %o4
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1: ld [%o1], %o5
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sub %o4, %o2, %g1
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add %o0, 4, %o0
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cmp %o4, %o5
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#ifdef EIGHTBIT_NOT_RARE
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andn %g1, %o4, %g1
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#endif
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bne 11f
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andcc %g1, %o3, %g0
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be 0b
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add %o1, 4, %o1
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srl %o4, 24, %g4
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andcc %g4, 0xff, %g0
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be 2f
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srl %o4, 16, %g4
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andcc %g4, 0xff, %g0
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be 2f
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srl %o4, 8, %g4
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andcc %g4, 0xff, %g0
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be 2f
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andcc %o4, 0xff, %g0
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bne,a 1b
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ld [%o0], %o4
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2: retl
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clr %o0
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11: srl %o4, 24, %g4
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srl %o5, 24, %g5
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andcc %g4, 0xff, %g0
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be 3f
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subcc %g4, %g5, %g4
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bne 3f
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srl %o5, 16, %g5
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srl %o4, 16, %g4
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andcc %g4, 0xff, %g0
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be 3f
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subcc %g4, %g5, %g4
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bne 3f
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srl %o5, 8, %g5
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srl %o4, 8, %g4
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andcc %g4, 0xff, %g0
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be 3f
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subcc %g4, %g5, %g4
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bne 3f
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subcc %o4, %o5, %o4
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retl
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mov %o4, %o0
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3: retl
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mov %g4, %o0
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12: save %sp, -64, %sp
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ld [%i0], %i4
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sll %g2, 3, %g3
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andn %i1, 3, %i1
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mov 32, %l1
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ld [%i1], %l2
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mov -1, %g6
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add %i1, 4, %i1
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sub %l1, %g3, %l1
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sll %g6, %g3, %g6
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1: sll %l2, %g3, %g5
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and %i4, %g6, %l3
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sub %i4, %i2, %g1
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#ifdef EIGHTBIT_NOT_RARE
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andn %g1, %i4, %g1
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#endif
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andcc %g1, %i3, %g1
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bne 3f
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cmp %g5, %l3
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bne 2f
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add %i0, 4, %i0
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ld [%i1], %l2
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add %i1, 4, %i1
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srl %l2, %l1, %l4
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or %l4, %g5, %l4
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cmp %l4, %i4
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be,a 1b
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ld [%i0], %i4
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restore %l4, %g0, %o3
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retl
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sub %o4, %o3, %o0
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2: sll %l2, %g3, %i2
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srl %i4, %g3, %i3
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srl %i2, %g3, %i2
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restore
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retl
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sub %o3, %o2, %o0
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3: srl %i4, 24, %g4
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srl %g5, 24, %l6
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andcc %g4, 0xff, %g0
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be 4f
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subcc %g4, %l6, %g4
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bne 4f
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cmp %g2, 3
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be 6f
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srl %i4, 16, %g4
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srl %g5, 16, %l6
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andcc %g4, 0xff, %g0
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be 4f
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subcc %g4, %l6, %g4
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bne 4f
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cmp %g2, 2
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be 5f
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srl %i4, 8, %g4
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srl %g5, 8, %l6
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andcc %g4, 0xff, %g0
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be 4f
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subcc %g4, %l6, %g4
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bne 4f
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add %i0, 4, %i0
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ld [%i1], %l2
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add %i1, 4, %i1
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srl %l2, 24, %g5
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andcc %i4, 0xff, %g4
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be 4f
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subcc %g4, %g5, %g4
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be,a 1b
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ld [%i0], %i4
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4: jmpl %i7 + 8, %g0
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restore %g4, %g0, %o0
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5: ld [%i1], %l2
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add %i1, 4, %i1
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add %i0, 4, %i0
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srl %l2, 24, %l6
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andcc %g4, 0xff, %g4
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be 4b
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subcc %g4, %l6, %g4
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bne 4b
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srl %l2, 16, %l6
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andcc %i4, 0xff, %g4
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and %l6, 0xff, %l6
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be 4b
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subcc %g4, %l6, %g4
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be,a 1b
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ld [%i0], %i4
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jmpl %i7 + 8, %g0
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restore %g4, %g0, %o0
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6: ld [%i1], %l2
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add %i1, 4, %i1
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add %i0, 4, %i0
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srl %l2, 24, %l6
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andcc %g4, 0xff, %g4
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be 4b
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subcc %g4, %l6, %g4
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bne 4b
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srl %l2, 16, %l6
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srl %i4, 8, %g4
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and %l6, 0xff, %l6
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andcc %g4, 0xff, %g4
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be 4b
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subcc %g4, %l6, %g4
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bne 4b
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srl %l2, 8, %l6
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andcc %i4, 0xff, %g4
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and %l6, 0xff, %l6
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be 4b
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subcc %g4, %l6, %g4
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be,a 1b
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ld [%i0], %i4
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jmpl %i7 + 8, %g0
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restore %g4, %g0, %o0
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END(strcmp)
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libc_hidden_builtin_def (strcmp)
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