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/* Optimized strcmp implementation for PowerPC64.
Copyright (C) 1997-2013 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<http://www.gnu.org/licenses/>. */
#include <sysdep.h>
#include <bp-sym.h>
#include <bp-asm.h>
/* See strlen.s for comments on how the end-of-string testing works. */
/* int [r3] strcmp (const char *s1 [r3], const char *s2 [r4]) */
EALIGN (BP_SYM(strcmp), 4, 0)
CALL_MCOUNT 2
#define rTMP r0
#define rRTN r3
#define rSTR1 r3 /* first string arg */
#define rSTR2 r4 /* second string arg */
/* Note: The Bounded pointer support in this code is broken. This code
was inherited from PPC32 and that support was never completed.
Current PPC gcc does not support -fbounds-check or -fbounded-pointers.
These artifacts are left in the code as a reminder in case we need
bounded pointer support in the future. */
#if __BOUNDED_POINTERS__
# define rHIGH1 r11
# define rHIGH2 r12
#endif
#define rWORD1 r5 /* current word in s1 */
#define rWORD2 r6 /* current word in s2 */
#define rFEFE r7 /* constant 0xfefefefefefefeff (-0x0101010101010101) */
#define r7F7F r8 /* constant 0x7f7f7f7f7f7f7f7f */
#define rNEG r9 /* ~(word in s1 | 0x7f7f7f7f7f7f7f7f) */
#define rBITDIF r10 /* bits that differ in s1 & s2 words */
CHECK_BOUNDS_LOW (rSTR1, rTMP, rHIGH1)
CHECK_BOUNDS_LOW (rSTR2, rTMP, rHIGH2)
dcbt 0,rSTR1
or rTMP, rSTR2, rSTR1
dcbt 0,rSTR2
clrldi. rTMP, rTMP, 61
lis rFEFE, -0x101
bne L(unaligned)
ld rWORD1, 0(rSTR1)
ld rWORD2, 0(rSTR2)
lis r7F7F, 0x7f7f
addi rFEFE, rFEFE, -0x101
addi r7F7F, r7F7F, 0x7f7f
sldi rTMP, rFEFE, 32
insrdi r7F7F, r7F7F, 32, 0
add rFEFE, rFEFE, rTMP
b L(g1)
L(g0): ldu rWORD1, 8(rSTR1)
bne cr1, L(different)
ldu rWORD2, 8(rSTR2)
L(g1): add rTMP, rFEFE, rWORD1
nor rNEG, r7F7F, rWORD1
and. rTMP, rTMP, rNEG
cmpd cr1, rWORD1, rWORD2
beq+ L(g0)
L(endstring):
/* OK. We've hit the end of the string. We need to be careful that
we don't compare two strings as different because of gunk beyond
the end of the strings... */
and rTMP, r7F7F, rWORD1
beq cr1, L(equal)
add rTMP, rTMP, r7F7F
xor. rBITDIF, rWORD1, rWORD2
andc rNEG, rNEG, rTMP
blt- L(highbit)
cntlzd rBITDIF, rBITDIF
cntlzd rNEG, rNEG
addi rNEG, rNEG, 7
cmpd cr1, rNEG, rBITDIF
sub rRTN, rWORD1, rWORD2
blt- cr1, L(equal)
sradi rRTN, rRTN, 63
ori rRTN, rRTN, 1
blr
L(equal):
li rRTN, 0
/* GKM FIXME: check high bounds. */
blr
L(different):
ld rWORD1, -8(rSTR1)
xor. rBITDIF, rWORD1, rWORD2
sub rRTN, rWORD1, rWORD2
blt- L(highbit)
sradi rRTN, rRTN, 63
ori rRTN, rRTN, 1
blr
L(highbit):
srdi rWORD2, rWORD2, 56
srdi rWORD1, rWORD1, 56
sub rRTN, rWORD1, rWORD2
/* GKM FIXME: check high bounds. */
blr
/* Oh well. In this case, we just do a byte-by-byte comparison. */
.align 4
L(unaligned):
lbz rWORD1, 0(rSTR1)
lbz rWORD2, 0(rSTR2)
b L(u1)
L(u0): lbzu rWORD1, 1(rSTR1)
bne- L(u4)
lbzu rWORD2, 1(rSTR2)
L(u1): cmpwi cr1, rWORD1, 0
beq- cr1, L(u3)
cmpd rWORD1, rWORD2
bne- L(u3)
lbzu rWORD1, 1(rSTR1)
lbzu rWORD2, 1(rSTR2)
cmpdi cr1, rWORD1, 0
cmpd rWORD1, rWORD2
bne+ cr1, L(u0)
L(u3): sub rRTN, rWORD1, rWORD2
/* GKM FIXME: check high bounds. */
blr
L(u4): lbz rWORD1, -1(rSTR1)
sub rRTN, rWORD1, rWORD2
/* GKM FIXME: check high bounds. */
blr
END (BP_SYM (strcmp))
libc_hidden_builtin_def (strcmp)
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