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183 lines
4.3 KiB
ArmAsm
183 lines
4.3 KiB
ArmAsm
/* Optimized strcmp implementation for POWER7/PowerPC64.
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Copyright (C) 2010, 2011 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., 51 Franklin Street, Fifth Floor, Boston MA
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02110-1301 USA. */
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#include <sysdep.h>
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#include <bp-sym.h>
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#include <bp-asm.h>
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/* See strlen.s for comments on how the end-of-string testing works. */
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/* int [r3] strncmp (const char *s1 [r3],
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const char *s2 [r4],
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size_t size [r5]) */
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EALIGN (BP_SYM(strncmp),4,0)
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CALL_MCOUNT 3
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#define rTMP r0
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#define rRTN r3
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#define rSTR1 r3 /* first string arg */
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#define rSTR2 r4 /* second string arg */
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#define rN r5 /* max string length */
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/* Note: The Bounded pointer support in this code is broken. This code
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was inherited from PPC32 and that support was never completed.
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Current PPC gcc does not support -fbounds-check or -fbounded-pointers. */
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#define rWORD1 r6 /* current word in s1 */
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#define rWORD2 r7 /* current word in s2 */
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#define rWORD3 r10
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#define rWORD4 r11
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#define rFEFE r8 /* constant 0xfefefefefefefeff (-0x0101010101010101) */
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#define r7F7F r9 /* constant 0x7f7f7f7f7f7f7f7f */
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#define rNEG r10 /* ~(word in s1 | 0x7f7f7f7f7f7f7f7f) */
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#define rBITDIF r11 /* bits that differ in s1 & s2 words */
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dcbt 0,rSTR1
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or rTMP,rSTR2,rSTR1
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lis r7F7F,0x7f7f
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dcbt 0,rSTR2
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clrldi. rTMP,rTMP,61
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cmpldi cr1,rN,0
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lis rFEFE,-0x101
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bne L(unaligned)
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/* We are doubleword alligned so set up for two loops. first a double word
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loop, then fall into the byte loop if any residual. */
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srdi. rTMP,rN,3
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clrldi rN,rN,61
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addi rFEFE,rFEFE,-0x101
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addi r7F7F,r7F7F,0x7f7f
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cmpldi cr1,rN,0
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beq L(unaligned)
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mtctr rTMP
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ld rWORD1,0(rSTR1)
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ld rWORD2,0(rSTR2)
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sldi rTMP,rFEFE,32
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insrdi r7F7F,r7F7F,32,0
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add rFEFE,rFEFE,rTMP
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b L(g1)
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L(g0):
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ldu rWORD1,8(rSTR1)
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bne cr1,L(different)
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ldu rWORD2,8(rSTR2)
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L(g1): add rTMP,rFEFE,rWORD1
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nor rNEG,r7F7F,rWORD1
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bdz L(tail)
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and. rTMP,rTMP,rNEG
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cmpd cr1,rWORD1,rWORD2
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beq L(g0)
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/* OK. We've hit the end of the string. We need to be careful that
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we don't compare two strings as different because of gunk beyond
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the end of the strings... */
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L(endstring):
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and rTMP,r7F7F,rWORD1
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beq cr1,L(equal)
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add rTMP,rTMP,r7F7F
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xor. rBITDIF,rWORD1,rWORD2
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andc rNEG,rNEG,rTMP
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blt L(highbit)
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cntlzd rBITDIF,rBITDIF
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cntlzd rNEG,rNEG
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addi rNEG,rNEG,7
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cmpd cr1,rNEG,rBITDIF
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sub rRTN,rWORD1,rWORD2
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blt cr1,L(equal)
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sradi rRTN,rRTN,63
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ori rRTN,rRTN,1
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blr
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L(equal):
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li rRTN,0
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blr
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L(different):
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ldu rWORD1,-8(rSTR1)
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xor. rBITDIF,rWORD1,rWORD2
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sub rRTN,rWORD1,rWORD2
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blt L(highbit)
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sradi rRTN,rRTN,63
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ori rRTN,rRTN,1
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blr
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L(highbit):
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srdi rWORD2,rWORD2,56
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srdi rWORD1,rWORD1,56
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sub rRTN,rWORD1,rWORD2
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blr
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/* Oh well. In this case, we just do a byte-by-byte comparison. */
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.align 4
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L(tail):
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and. rTMP,rTMP,rNEG
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cmpd cr1,rWORD1,rWORD2
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bne L(endstring)
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addi rSTR1,rSTR1,8
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bne cr1,L(different)
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addi rSTR2,rSTR2,8
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cmpldi cr1,rN,0
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L(unaligned):
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mtctr rN
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ble cr1,L(ux)
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L(uz):
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lbz rWORD1,0(rSTR1)
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lbz rWORD2,0(rSTR2)
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.align 4
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L(u1):
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cmpdi cr1,rWORD1,0
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bdz L(u4)
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cmpd rWORD1,rWORD2
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beq cr1,L(u4)
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bne L(u4)
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lbzu rWORD3,1(rSTR1)
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lbzu rWORD4,1(rSTR2)
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cmpdi cr1,rWORD3,0
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bdz L(u3)
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cmpd rWORD3,rWORD4
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beq cr1,L(u3)
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bne L(u3)
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lbzu rWORD1,1(rSTR1)
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lbzu rWORD2,1(rSTR2)
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cmpdi cr1,rWORD1,0
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bdz L(u4)
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cmpd rWORD1,rWORD2
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beq cr1,L(u4)
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bne L(u4)
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lbzu rWORD3,1(rSTR1)
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lbzu rWORD4,1(rSTR2)
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cmpdi cr1,rWORD3,0
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bdz L(u3)
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cmpd rWORD3,rWORD4
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beq cr1,L(u3)
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bne L(u3)
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lbzu rWORD1,1(rSTR1)
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lbzu rWORD2,1(rSTR2)
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b L(u1)
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L(u3): sub rRTN,rWORD3,rWORD4
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blr
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L(u4): sub rRTN,rWORD1,rWORD2
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blr
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L(ux):
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li rRTN,0
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blr
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END (BP_SYM (strncmp))
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libc_hidden_builtin_def (strncmp)
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