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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>
164 lines
4.9 KiB
ArmAsm
164 lines
4.9 KiB
ArmAsm
/* Optimized version of the standard memcmp() 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 result of the comparison
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Inputs:
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in0: dest (aka s1)
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in1: src (aka s2)
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in2: byte count
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In this form, it assumes little endian mode. For big endian mode,
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the two shifts in .l2 must be inverted:
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shl tmp1[0] = r[1 + MEMLAT], sh1 // tmp1 = w0 << sh1
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shr.u tmp2[0] = r[0 + MEMLAT], sh2 // tmp2 = w1 >> sh2
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and all the mux1 instructions should be replaced by plain mov's. */
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#include <sysdep.h>
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#undef ret
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#define OP_T_THRES 16
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#define OPSIZ 8
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#define MEMLAT 2
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#define start r15
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#define saved_pr r17
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#define saved_lc r18
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#define dest r19
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#define src r20
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#define len r21
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#define asrc r22
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#define tmp r23
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#define value1 r24
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#define value2 r25
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#define sh2 r28
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#define sh1 r29
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#define loopcnt r30
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ENTRY(memcmp)
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.prologue
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alloc r2 = ar.pfs, 3, 37, 0, 40
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.rotr r[MEMLAT + 2], q[MEMLAT + 5], tmp1[4], tmp2[4], val[2]
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.rotp p[MEMLAT + 4 + 1]
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mov ret0 = r0 // by default return value = 0
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.save pr, saved_pr
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mov saved_pr = pr // save the predicate registers
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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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.body
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mov dest = in0 // dest
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mov src = in1 // src
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mov len = in2 // len
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sub tmp = r0, in0 // tmp = -dest
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;;
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and loopcnt = 7, tmp // loopcnt = -dest % 8
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cmp.ge p6, p0 = OP_T_THRES, len // is len <= OP_T_THRES
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(p6) br.cond.spnt .cmpfew // compare byte by byte
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;;
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cmp.eq p6, p0 = loopcnt, r0
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(p6) br.cond.sptk .dest_aligned
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sub len = len, loopcnt // len -= -dest % 8
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adds loopcnt = -1, loopcnt // --loopcnt
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;;
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mov ar.lc = loopcnt
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.l1: // copy -dest % 8 bytes
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ld1 value1 = [src], 1 // value = *src++
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ld1 value2 = [dest], 1
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;;
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cmp.ne p6, p0 = value1, value2
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(p6) br.cond.spnt .done
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br.cloop.dptk .l1
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.dest_aligned:
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and sh1 = 7, src // sh1 = src % 8
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and tmp = -8, len // tmp = len & -OPSIZ
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and asrc = -8, src // asrc = src & -OPSIZ -- align src
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shr.u loopcnt = len, 3 // loopcnt = len / 8
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and len = 7, len ;; // len = len % 8
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shl sh1 = sh1, 3 // sh1 = 8 * (src % 8)
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adds loopcnt = -1, loopcnt // --loopcnt
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mov pr.rot = 1 << 16 ;; // set rotating predicates
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sub sh2 = 64, sh1 // sh2 = 64 - sh1
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mov ar.lc = loopcnt // set LC
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cmp.eq p6, p0 = sh1, r0 // is the src aligned?
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(p6) br.cond.sptk .src_aligned
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add src = src, tmp // src += len & -OPSIZ
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mov ar.ec = MEMLAT + 4 + 1 // four more passes needed
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ld8 r[1] = [asrc], 8 ;; // r[1] = w0
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.align 32
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// We enter this loop with p6 cleared by the above comparison
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.l2:
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(p[0]) ld8 r[0] = [asrc], 8 // r[0] = w1
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(p[0]) ld8 q[0] = [dest], 8
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(p[MEMLAT]) shr.u tmp1[0] = r[1 + MEMLAT], sh1 // tmp1 = w0 >> sh1
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(p[MEMLAT]) shl tmp2[0] = r[0 + MEMLAT], sh2 // tmp2 = w1 << sh2
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(p[MEMLAT+4]) cmp.ne p6, p0 = q[MEMLAT + 4], val[1]
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(p[MEMLAT+3]) or val[0] = tmp1[3], tmp2[3] // val = tmp1 | tmp2
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(p6) br.cond.spnt .l2exit
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br.ctop.sptk .l2
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br.cond.sptk .cmpfew
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.l3exit:
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mux1 value1 = r[MEMLAT], @rev
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mux1 value2 = q[MEMLAT], @rev
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cmp.ne p6, p0 = r0, r0 ;; // clear p6
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.l2exit:
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(p6) mux1 value1 = val[1], @rev
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(p6) mux1 value2 = q[MEMLAT + 4], @rev ;;
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cmp.ltu p6, p7 = value2, value1 ;;
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(p6) mov ret0 = -1
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(p7) mov ret0 = 1
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mov pr = saved_pr, -1 // restore the predicate registers
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mov ar.lc = saved_lc // restore the loop counter
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br.ret.sptk.many b0
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.src_aligned:
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cmp.ne p6, p0 = r0, r0 // clear p6
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mov ar.ec = MEMLAT + 1 ;; // set EC
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.l3:
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(p[0]) ld8 r[0] = [src], 8
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(p[0]) ld8 q[0] = [dest], 8
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(p[MEMLAT]) cmp.ne p6, p0 = r[MEMLAT], q[MEMLAT]
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(p6) br.cond.spnt .l3exit
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br.ctop.dptk .l3 ;;
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.cmpfew:
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cmp.eq p6, p0 = len, r0 // is len == 0 ?
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adds len = -1, len // --len;
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(p6) br.cond.spnt .restore_and_exit ;;
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mov ar.lc = len
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.l4:
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ld1 value1 = [src], 1
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ld1 value2 = [dest], 1
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;;
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cmp.ne p6, p0 = value1, value2
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(p6) br.cond.spnt .done
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br.cloop.dptk .l4 ;;
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.done:
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(p6) sub ret0 = value2, value1 // don't execute it if falling thru
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.restore_and_exit:
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mov pr = saved_pr, -1 // restore the predicate registers
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mov ar.lc = saved_lc // restore the loop counter
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br.ret.sptk.many b0
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END(memcmp)
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weak_alias (memcmp, bcmp)
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libc_hidden_builtin_def (memcmp)
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