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45b1e17e91
DELOUSE was added to asm code to make them compatible with non-LP64 ABIs, but it is an unfortunate name and the code was not compatible with ABIs where pointer and size_t are different. Glibc currently only supports the LP64 ABI so these macros are not really needed or tested, but for now the name is changed to be more meaningful instead of removing them completely. Some DELOUSE macros were dropped: clone, strlen and strnlen used it unnecessarily. The out of tree ILP32 patches are currently not maintained and will likely need a rework to rebase them on top of the time64 changes.
133 lines
3.3 KiB
ArmAsm
133 lines
3.3 KiB
ArmAsm
/* memrchr - find the last occurrence of a byte in a memory block
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Copyright (C) 2015-2020 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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/* Assumptions:
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*
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* ARMv8-a, AArch64, Advanced SIMD.
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* MTE compatible.
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*/
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/* Arguments and results. */
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#define srcin x0
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#define chrin w1
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#define cntin x2
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#define result x0
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#define src x3
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#define cntrem x4
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#define synd x5
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#define shift x6
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#define tmp x7
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#define wtmp w7
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#define end x8
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#define endm1 x9
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#define vrepchr v0
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#define qdata q1
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#define vdata v1
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#define vhas_chr v2
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#define vrepmask v3
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#define vend v4
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#define dend d4
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/*
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Core algorithm:
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For each 16-byte chunk we calculate a 64-bit syndrome value with four bits
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per byte. For even bytes, bits 0-3 are set if the relevant byte matched the
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requested character or the byte is NUL. Bits 4-7 must be zero. Bits 4-7 are
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set likewise for odd bytes so that adjacent bytes can be merged. Since the
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bits in the syndrome reflect the order in which things occur in the original
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string, counting trailing zeros identifies exactly which byte matched. */
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ENTRY (__memrchr)
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PTR_ARG (0)
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SIZE_ARG (2)
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add end, srcin, cntin
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sub endm1, end, 1
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bic src, endm1, 15
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cbz cntin, L(nomatch)
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ld1 {vdata.16b}, [src]
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dup vrepchr.16b, chrin
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mov wtmp, 0xf00f
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dup vrepmask.8h, wtmp
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cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
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neg shift, end, lsl 2
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and vhas_chr.16b, vhas_chr.16b, vrepmask.16b
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addp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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lsl synd, synd, shift
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cbz synd, L(start_loop)
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clz synd, synd
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sub result, endm1, synd, lsr 2
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cmp cntin, synd, lsr 2
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csel result, result, xzr, hi
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ret
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L(start_loop):
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sub tmp, end, src
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subs cntrem, cntin, tmp
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b.ls L(nomatch)
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/* Make sure that it won't overread by a 16-byte chunk */
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add tmp, cntrem, 15
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tbnz tmp, 4, L(loop32_2)
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.p2align 4
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L(loop32):
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ldr qdata, [src, -16]!
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cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
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umaxp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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cbnz synd, L(end)
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L(loop32_2):
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ldr qdata, [src, -16]!
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subs cntrem, cntrem, 32
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cmeq vhas_chr.16b, vdata.16b, vrepchr.16b
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b.ls L(end)
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umaxp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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cbz synd, L(loop32)
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L(end):
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and vhas_chr.16b, vhas_chr.16b, vrepmask.16b
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addp vend.16b, vhas_chr.16b, vhas_chr.16b /* 128->64 */
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fmov synd, dend
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add tmp, src, 15
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#ifdef __AARCH64EB__
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rbit synd, synd
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#endif
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clz synd, synd
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sub tmp, tmp, synd, lsr 2
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cmp tmp, srcin
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csel result, tmp, xzr, hs
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ret
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L(nomatch):
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mov result, 0
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ret
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END (__memrchr)
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weak_alias (__memrchr, memrchr)
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libc_hidden_builtin_def (memrchr)
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