2019-01-01 00:11:28 +00:00
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/* Copyright (C) 1996-2019 Free Software Foundation, Inc.
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1996-11-06 04:24:11 +00:00
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Contributed by Richard Henderson (rth@tamu.edu)
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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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2001-07-06 04:56:23 +00:00
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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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1996-11-06 04:24:11 +00:00
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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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2001-07-06 04:56:23 +00:00
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Lesser General Public License for more details.
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1996-11-06 04:24:11 +00:00
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2001-07-06 04:56:23 +00:00
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You should have received a copy of the GNU Lesser General Public
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2012-03-09 23:56:38 +00:00
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License along with the GNU C Library. If not, see
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Prefer https to http for gnu.org and fsf.org URLs
Also, change sources.redhat.com to sourceware.org.
This patch was automatically generated by running the following shell
script, which uses GNU sed, and which avoids modifying files imported
from upstream:
sed -ri '
s,(http|ftp)(://(.*\.)?(gnu|fsf|sourceware)\.org($|[^.]|\.[^a-z])),https\2,g
s,(http|ftp)(://(.*\.)?)sources\.redhat\.com($|[^.]|\.[^a-z]),https\2sourceware.org\4,g
' \
$(find $(git ls-files) -prune -type f \
! -name '*.po' \
! -name 'ChangeLog*' \
! -path COPYING ! -path COPYING.LIB \
! -path manual/fdl-1.3.texi ! -path manual/lgpl-2.1.texi \
! -path manual/texinfo.tex ! -path scripts/config.guess \
! -path scripts/config.sub ! -path scripts/install-sh \
! -path scripts/mkinstalldirs ! -path scripts/move-if-change \
! -path INSTALL ! -path locale/programs/charmap-kw.h \
! -path po/libc.pot ! -path sysdeps/gnu/errlist.c \
! '(' -name configure \
-execdir test -f configure.ac -o -f configure.in ';' ')' \
! '(' -name preconfigure \
-execdir test -f preconfigure.ac ';' ')' \
-print)
and then by running 'make dist-prepare' to regenerate files built
from the altered files, and then executing the following to cleanup:
chmod a+x sysdeps/unix/sysv/linux/riscv/configure
# Omit irrelevant whitespace and comment-only changes,
# perhaps from a slightly-different Autoconf version.
git checkout -f \
sysdeps/csky/configure \
sysdeps/hppa/configure \
sysdeps/riscv/configure \
sysdeps/unix/sysv/linux/csky/configure
# Omit changes that caused a pre-commit check to fail like this:
# remote: *** error: sysdeps/powerpc/powerpc64/ppc-mcount.S: trailing lines
git checkout -f \
sysdeps/powerpc/powerpc64/ppc-mcount.S \
sysdeps/unix/sysv/linux/s390/s390-64/syscall.S
# Omit change that caused a pre-commit check to fail like this:
# remote: *** error: sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S: last line does not end in newline
git checkout -f sysdeps/sparc/sparc64/multiarch/memcpy-ultra3.S
2019-09-07 05:40:42 +00:00
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<https://www.gnu.org/licenses/>. */
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1996-11-06 04:24:11 +00:00
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/* Bytewise compare two null-terminated strings. */
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#include <sysdep.h>
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.set noat
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.set noreorder
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.text
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ENTRY(strcmp)
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#ifdef PROF
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ldgp gp, 0(pv)
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lda AT, _mcount
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jmp AT, (AT), _mcount
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.prologue 1
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#else
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.prologue 0
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#endif
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ldq_u t0, 0(a0) # e0 : give cache time to catch up
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xor a0, a1, t2 # .. e1 : are s1 and s2 co-aligned?
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ldq_u t1, 0(a1) # e0 :
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and t2, 7, t2 # .. e1 :
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lda t3, -1 # e0 :
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bne t2, $unaligned # .. e1 :
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/* On entry to this basic block:
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t0 == the first destination word for masking back in
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t1 == the first source word.
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t3 == -1. */
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$aligned:
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mskqh t3, a0, t3 # e0 :
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nop # .. e1 :
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ornot t1, t3, t1 # e0 :
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ornot t0, t3, t0 # .. e1 :
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cmpbge zero, t1, t7 # e0 : bits set iff null found
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bne t7, $eos # e1 (zdb)
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/* Aligned compare main loop.
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On entry to this basic block:
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t0 == an s1 word.
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t1 == an s2 word not containing a null. */
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$a_loop:
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xor t0, t1, t2 # e0 :
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bne t2, $wordcmp # .. e1 (zdb)
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ldq_u t1, 8(a1) # e0 :
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ldq_u t0, 8(a0) # .. e1 :
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addq a1, 8, a1 # e0 :
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addq a0, 8, a0 # .. e1 :
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cmpbge zero, t1, t7 # e0 :
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beq t7, $a_loop # .. e1 (zdb)
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br $eos # e1 :
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/* The two strings are not co-aligned. Align s1 and cope. */
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$unaligned:
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and a0, 7, t4 # e0 : find s1 misalignment
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and a1, 7, t5 # .. e1 : find s2 misalignment
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subq a1, t4, a1 # e0 :
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/* If s2 misalignment is larger than s2 misalignment, we need
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extra startup checks to avoid SEGV. */
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cmplt t4, t5, t8 # .. e1 :
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beq t8, $u_head # e1 :
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mskqh t3, t5, t3 # e0 :
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ornot t1, t3, t3 # e0 :
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cmpbge zero, t3, t7 # e1 : is there a zero?
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beq t7, $u_head # e1 :
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/* We've found a zero in the first partial word of s2. Align
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our current s1 and s2 words and compare what we've got. */
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extql t1, t5, t1 # e0 :
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extql t0, a0, t0 # e0 :
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cmpbge zero, t1, t7 # .. e1 : find that zero again
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br $eos # e1 : and finish up
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.align 3
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$u_head:
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/* We know just enough now to be able to assemble the first
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full word of s2. We can still find a zero at the end of it.
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On entry to this basic block:
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t0 == first word of s1
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t1 == first partial word of s2. */
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ldq_u t2, 8(a1) # e0 : load second partial s2 word
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lda t3, -1 # .. e1 : create leading garbage mask
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extql t1, a1, t1 # e0 : create first s2 word
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mskqh t3, a0, t3 # e0 :
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extqh t2, a1, t4 # e0 :
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ornot t0, t3, t0 # .. e1 : kill s1 garbage
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or t1, t4, t1 # e0 : s2 word now complete
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cmpbge zero, t0, t7 # .. e1 : find zero in first s1 word
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ornot t1, t3, t1 # e0 : kill s2 garbage
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lda t3, -1 # .. e1 :
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mskql t3, a1, t3 # e0 : mask for s2[1] bits we have seen
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bne t7, $eos # .. e1 :
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xor t0, t1, t4 # e0 : compare aligned words
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bne t4, $wordcmp # .. e1 (zdb)
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or t2, t3, t3 # e0 :
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cmpbge zero, t3, t7 # e1 :
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bne t7, $u_final # e1 :
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/* Unaligned copy main loop. In order to avoid reading too much,
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the loop is structured to detect zeros in aligned words from s2.
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This has, unfortunately, effectively pulled half of a loop
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iteration out into the head and half into the tail, but it does
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prevent nastiness from accumulating in the very thing we want
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to run as fast as possible.
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On entry to this basic block:
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t2 == the unshifted low-bits from the next s2 word. */
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.align 3
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$u_loop:
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extql t2, a1, t3 # e0 :
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ldq_u t2, 16(a1) # .. e1 : load next s2 high bits
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ldq_u t0, 8(a0) # e0 : load next s1 word
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addq a1, 8, a1 # .. e1 :
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addq a0, 8, a0 # e0 :
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nop # .. e1 :
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extqh t2, a1, t1 # e0 :
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cmpbge zero, t0, t7 # .. e1 : find zero in current s1 word
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or t1, t3, t1 # e0 :
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bne t7, $eos # .. e1 :
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xor t0, t1, t4 # e0 : compare the words
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bne t4, $wordcmp # .. e1 (zdb)
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cmpbge zero, t2, t4 # e0 : find zero in next low bits
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beq t4, $u_loop # .. e1 (zdb)
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/* We've found a zero in the low bits of the last s2 word. Get
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the next s1 word and align them. */
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$u_final:
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ldq_u t0, 8(a0) # e1 :
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extql t2, a1, t1 # .. e0 :
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cmpbge zero, t1, t7 # e0 :
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/* We've found a zero somewhere in a word we just read.
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On entry to this basic block:
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t0 == s1 word
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t1 == s2 word
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t7 == cmpbge mask containing the zero. */
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.align 3
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$eos:
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negq t7, t6 # e0 : create bytemask of valid data
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and t6, t7, t8 # e1 :
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subq t8, 1, t6 # e0 :
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or t6, t8, t7 # e1 :
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zapnot t0, t7, t0 # e0 : kill the garbage
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zapnot t1, t7, t1 # .. e1 :
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xor t0, t1, v0 # e0 : and compare
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beq v0, $done # .. e1 :
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/* Here we have two differing co-aligned words in t0 & t1.
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1997-06-26 22:16:52 +00:00
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Bytewise compare them and return (t0 > t1 ? 1 : -1). */
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1996-11-06 04:24:11 +00:00
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$wordcmp:
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cmpbge t0, t1, t2 # e0 : comparison yields bit mask of ge
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cmpbge t1, t0, t3 # .. e1 :
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xor t2, t3, t0 # e0 : bits set iff t0/t1 bytes differ
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negq t0, t1 # e1 : clear all but least bit
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and t0, t1, t0 # e0 :
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lda v0, -1 # .. e1 :
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and t0, t2, t1 # e0 : was bit set in t0 > t1?
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cmovne t1, 1, v0 # .. e1 (zdb)
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$done:
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ret # e1 :
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END(strcmp)
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2003-04-29 22:47:20 +00:00
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libc_hidden_builtin_def (strcmp)
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