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30891f35fa
We stopped adding "Contributed by" or similar lines in sources in 2012 in favour of git logs and keeping the Contributors section of the glibc manual up to date. Removing these lines makes the license header a bit more consistent across files and also removes the possibility of error in attribution when license blocks or files are copied across since the contributed-by lines don't actually reflect reality in those cases. Move all "Contributed by" and similar lines (Written by, Test by, etc.) into a new file CONTRIBUTED-BY to retain record of these contributions. These contributors are also mentioned in manual/contrib.texi, so we just maintain this additional record as a courtesy to the earlier developers. The following scripts were used to filter a list of files to edit in place and to clean up the CONTRIBUTED-BY file respectively. These were not added to the glibc sources because they're not expected to be of any use in future given that this is a one time task: https://gist.github.com/siddhesh/b5ecac94eabfd72ed2916d6d8157e7dc https://gist.github.com/siddhesh/15ea1f5e435ace9774f485030695ee02 Reviewed-by: Carlos O'Donell <carlos@redhat.com>
161 lines
4.8 KiB
ArmAsm
161 lines
4.8 KiB
ArmAsm
/* Optimized version of the standard memchr() function.
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This file is part of the GNU C Library.
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Copyright (C) 2000-2021 Free Software Foundation, Inc.
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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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/* Return: the address of the first occurence of chr in str or NULL
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Inputs:
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in0: str
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in1: chr
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in2: byte count
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This implementation assumes little endian mode. For big endian mode,
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the instruction czx1.r should be replaced by czx1.l.
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The algorithm is fairly straightforward: search byte by byte until we
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we get to a word aligned address, then search word by word as much as
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possible; the remaining few bytes are searched one at a time.
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The word by word search is performed by xor-ing the word with a word
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containing chr in every byte. If there is a hit, the result will
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contain a zero byte in the corresponding position. The presence and
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position of that zero byte is detected with a czx instruction.
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All the loops in this function could have had the internal branch removed
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if br.ctop and br.cloop could be predicated :-(. */
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#include <sysdep.h>
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#undef ret
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#define saved_pr r15
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#define saved_lc r16
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#define chr r17
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#define len r18
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#define last r20
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#define val r21
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#define tmp r24
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#define chrx8 r25
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#define loopcnt r30
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#define str in0
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ENTRY(__memchr)
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.prologue
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alloc r2 = ar.pfs, 3, 0, 29, 32
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#include "softpipe.h"
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.rotr value[MEMLAT+1], addr[MEMLAT+3], aux[2], poschr[2]
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.rotp p[MEMLAT+3]
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.save ar.lc, saved_lc
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mov saved_lc = ar.lc // save the loop counter
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.save pr, saved_pr
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mov saved_pr = pr // save the predicates
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.body
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mov ret0 = str
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add last = str, in2 // last byte
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;;
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cmp.ltu p6, p0 = last, str
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;;
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(p6) mov last = -1
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and tmp = 7, str // tmp = str % 8
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cmp.ne p7, p0 = r0, r0 // clear p7
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extr.u chr = in1, 0, 8 // chr = (unsigned char) in1
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mov len = in2
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cmp.gtu p6, p0 = 16, in2 // use a simple loop for short
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(p6) br.cond.spnt .srchfew ;; // searches
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sub loopcnt = 8, tmp // loopcnt = 8 - tmp
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cmp.eq p6, p0 = tmp, r0
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(p6) br.cond.sptk .str_aligned;;
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sub len = len, loopcnt
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adds loopcnt = -1, loopcnt;;
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mov ar.lc = loopcnt
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.l1:
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ld1 val = [ret0], 1
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;;
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cmp.eq p6, p0 = val, chr
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(p6) br.cond.spnt .foundit
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br.cloop.sptk .l1 ;;
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.str_aligned:
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cmp.ne p6, p0 = r0, r0 // clear p6
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shr.u loopcnt = len, 3 // loopcnt = len / 8
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and len = 7, len ;; // remaining len = len & 7
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adds loopcnt = -1, loopcnt
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mov ar.ec = MEMLAT + 3
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mux1 chrx8 = chr, @brcst ;; // get a word full of chr
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mov ar.lc = loopcnt
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mov pr.rot = 1 << 16 ;;
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.l2:
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(p[0]) mov addr[0] = ret0
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(p[0]) ld8.s value[0] = [ret0], 8 // speculative load
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(p[MEMLAT]) chk.s value[MEMLAT], .recovery // check and recovery
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(p[MEMLAT]) xor aux[0] = value[MEMLAT], chrx8
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(p[MEMLAT+1]) czx1.r poschr[0] = aux[1]
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(p[MEMLAT+2]) cmp.ne p7, p0 = 8, poschr[1]
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(p7) br.cond.dpnt .foundit
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br.ctop.dptk .l2
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.srchfew:
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adds loopcnt = -1, len
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cmp.eq p6, p0 = len, r0
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(p6) br.cond.spnt .notfound ;;
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mov ar.lc = loopcnt
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.l3:
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ld1 val = [ret0], 1
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;;
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cmp.eq p6, p0 = val, chr
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(p6) br.cond.dpnt .foundit
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br.cloop.sptk .l3 ;;
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.notfound:
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cmp.ne p6, p0 = r0, r0 // clear p6 (p7 was already 0 when we got here)
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mov ret0 = r0 ;; // return NULL
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.foundit:
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.pred.rel "mutex" p6, p7
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(p6) adds ret0 = -1, ret0 // if we got here from l1 or l3
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(p7) add ret0 = addr[MEMLAT+2], poschr[1] // if we got here from l2
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mov pr = saved_pr, -1
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mov ar.lc = saved_lc
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br.ret.sptk.many b0
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.recovery:
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#if MEMLAT != 6
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# error "MEMLAT must be 6!"
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#endif
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(p[MEMLAT-6]) add ret0 = -8, ret0;;
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(p[MEMLAT-5]) add ret0 = -8, ret0;;
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(p[MEMLAT-4]) add ret0 = -8, ret0;;
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(p[MEMLAT-3]) add ret0 = -8, ret0;;
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(p[MEMLAT-2]) add ret0 = -8, ret0;;
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(p[MEMLAT-1]) add ret0 = -8, ret0;;
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(p[MEMLAT]) add ret0 = -8, ret0;;
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(p[MEMLAT+1]) add ret0 = -8, ret0;;
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(p[MEMLAT+2]) add ret0 = -8, ret0;;
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.l4:
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mov addr[MEMLAT+2] = ret0
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ld8 tmp = [ret0];; // load the first unchecked 8byte
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xor aux[1] = tmp, chrx8;;
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czx1.r poschr[1] = aux[1];;
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cmp.ne p7, p0 = 8, poschr[1];;
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(p7) add ret0 = addr[MEMLAT+2], poschr[1];;
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(p7) cmp.geu p6, p7 = ret0, last // don't go over the last byte
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(p6) br.cond.spnt .notfound;;
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(p7) br.cond.spnt .foundit;;
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adds ret0 = 8, ret0 // load the next unchecked 8byte
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br.sptk .l4;;
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END(__memchr)
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weak_alias (__memchr, memchr)
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libc_hidden_builtin_def (memchr)
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