232 lines
5.2 KiB
ArmAsm
232 lines
5.2 KiB
ArmAsm
/* Compare two strings for differences.
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For SPARC v9.
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Copyright (C) 2011-2022 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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#include <asm/asi.h>
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#ifndef XCC
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.register %g2, #scratch
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.register %g3, #scratch
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.register %g6, #scratch
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#endif
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#define rSTR1 %o0
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#define rSTR2 %o1
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#define r0101 %o2 /* 0x0101010101010101 */
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#define r8080 %o3 /* 0x8080808080808080 */
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#define rSTRXOR %o4
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#define rWORD1 %o5
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#define rTMP1 %g1
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#define rTMP2 %g2
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#define rWORD2 %g3
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#define rSLL %g4
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#define rSRL %g5
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#define rBARREL %g6
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/* There are two cases, either the two pointers are aligned
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* identically or they are not. If they have the same
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* alignment we can use the normal full speed loop. Otherwise
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* we have to use the barrel-shifter version.
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*/
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.text
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.align 32
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ENTRY(strcmp)
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or rSTR2, rSTR1, rTMP1
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sethi %hi(0x80808080), r8080
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andcc rTMP1, 0x7, %g0
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bne,pn %icc, .Lmaybe_barrel_shift
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or r8080, %lo(0x80808080), r8080
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ldx [rSTR1], rWORD1
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sub rSTR2, rSTR1, rSTR2
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sllx r8080, 32, rTMP1
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ldx [rSTR1 + rSTR2], rWORD2
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or r8080, rTMP1, r8080
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ba,pt %xcc, .Laligned_loop_entry
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srlx r8080, 7, r0101
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.align 32
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.Laligned_loop_entry:
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.Laligned_loop:
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add rSTR1, 8, rSTR1
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sub rWORD1, r0101, rTMP2
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xorcc rWORD1, rWORD2, rSTRXOR
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bne,pn %xcc, .Lcommon_endstring
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andn r8080, rWORD1, rTMP1
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ldxa [rSTR1] ASI_PNF, rWORD1
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andcc rTMP1, rTMP2, %g0
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be,a,pt %xcc, .Laligned_loop
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ldxa [rSTR1 + rSTR2] ASI_PNF, rWORD2
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.Lcommon_equal:
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retl
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mov 0, %o0
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/* All loops terminate here once they find an unequal word.
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* If a zero byte appears in the word before the first unequal
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* byte, we must report zero. Otherwise we report '1' or '-1'
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* depending upon whether the first mis-matching byte is larger
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* in the first string or the second, respectively.
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*
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* First we compute a 64-bit mask value that has "0x01" in
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* each byte where a zero exists in rWORD1. rSTRXOR holds the
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* value (rWORD1 ^ rWORD2). Therefore, if considered as an
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* unsigned quantity, our "0x01" mask value is "greater than"
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* rSTRXOR then a zero terminating byte comes first and
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* therefore we report '0'.
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*
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* The formula for this mask is:
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*
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* mask_tmp1 = ~rWORD1 & 0x8080808080808080;
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* mask_tmp2 = ((rWORD1 & 0x7f7f7f7f7f7f7f7f) +
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* 0x7f7f7f7f7f7f7f7f);
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*
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* mask = ((mask_tmp1 & ~mask_tmp2) >> 7);
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*/
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.Lcommon_endstring:
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andn rWORD1, r8080, rTMP2
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or r8080, 1, %o1
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mov 1, %o0
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sub rTMP2, %o1, rTMP2
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cmp rWORD1, rWORD2
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andn rTMP1, rTMP2, rTMP1
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movleu %xcc, -1, %o0
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srlx rTMP1, 7, rTMP1
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/* In order not to be influenced by bytes after the zero byte, we
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* have to retain only the highest bit in the mask for the comparison
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* with rSTRXOR to work properly.
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*/
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mov 0, rTMP2
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andcc rTMP1, 0x0100, %g0
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movne %xcc, 8, rTMP2
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sllx rTMP1, 63 - 16, %o1
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movrlz %o1, 16, rTMP2
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sllx rTMP1, 63 - 24, %o1
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movrlz %o1, 24, rTMP2
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sllx rTMP1, 63 - 32, %o1
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movrlz %o1, 32, rTMP2
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sllx rTMP1, 63 - 40, %o1
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movrlz %o1, 40, rTMP2
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sllx rTMP1, 63 - 48, %o1
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movrlz %o1, 48, rTMP2
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sllx rTMP1, 63 - 56, %o1
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movrlz %o1, 56, rTMP2
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srlx rTMP1, rTMP2, rTMP1
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sllx rTMP1, rTMP2, rTMP1
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cmp rTMP1, rSTRXOR
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retl
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movgu %xcc, 0, %o0
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.Lmaybe_barrel_shift:
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sub rSTR2, rSTR1, rSTR2
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sllx r8080, 32, rTMP1
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or r8080, rTMP1, r8080
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and rSTR1, 0x7, rTMP2
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srlx r8080, 7, r0101
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andn rSTR1, 0x7, rSTR1
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ldxa [rSTR1] ASI_PNF, rWORD1
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andcc rSTR2, 0x7, rSLL
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sll rTMP2, 3, rSTRXOR
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bne,pn %icc, .Lneed_barrel_shift
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mov -1, rTMP1
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ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
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srlx rTMP1, rSTRXOR, rTMP2
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orn rWORD1, rTMP2, rWORD1
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ba,pt %xcc, .Laligned_loop_entry
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orn rBARREL, rTMP2, rWORD2
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.Lneed_barrel_shift:
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sllx rSLL, 3, rSLL
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andn rSTR2, 0x7, rSTR2
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ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
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mov 64, rTMP2
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sub rTMP2, rSLL, rSRL
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srlx rTMP1, rSTRXOR, rTMP1
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add rSTR2, 8, rSTR2
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orn rWORD1, rTMP1, rWORD1
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sllx rBARREL, rSLL, rWORD2
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ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
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add rSTR1, 8, rSTR1
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sub rWORD1, r0101, rTMP2
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srlx rBARREL, rSRL, rSTRXOR
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or rWORD2, rSTRXOR, rWORD2
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orn rWORD2, rTMP1, rWORD2
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ba,pt %xcc, .Lbarrel_shift_loop_entry
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andn r8080, rWORD1, rTMP1
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.Lbarrel_shift_loop:
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sllx rBARREL, rSLL, rWORD2
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ldxa [rSTR1 + rSTR2] ASI_PNF, rBARREL
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add rSTR1, 8, rSTR1
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sub rWORD1, r0101, rTMP2
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srlx rBARREL, rSRL, rSTRXOR
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andn r8080, rWORD1, rTMP1
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or rWORD2, rSTRXOR, rWORD2
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.Lbarrel_shift_loop_entry:
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xorcc rWORD1, rWORD2, rSTRXOR
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bne,pn %xcc, .Lcommon_endstring
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andcc rTMP1, rTMP2, %g0
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be,a,pt %xcc, .Lbarrel_shift_loop
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ldxa [rSTR1] ASI_PNF, rWORD1
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retl
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mov 0, %o0
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END(strcmp)
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libc_hidden_builtin_def (strcmp)
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