117 lines
3.6 KiB
ArmAsm
117 lines
3.6 KiB
ArmAsm
/* Copyright (C) 2000-2022 Free Software Foundation, Inc.
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EV67 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
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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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/* Return the address of the last occurrence of a given character
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within a null-terminated string, or null if it is not found. */
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#include <sysdep.h>
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.arch ev6
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.set noreorder
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.set noat
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ENTRY(strrchr)
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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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jsr 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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and a1, 0xff, t2 # E : 00000000000000ch
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insbl a1, 1, t4 # U : 000000000000ch00
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insbl a1, 2, t5 # U : 0000000000ch0000
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ldq_u t0, 0(a0) # L : load first quadword Latency=3
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mov zero, t6 # E : t6 is last match aligned addr
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or t2, t4, a1 # E : 000000000000chch
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sll t5, 8, t3 # U : 00000000ch000000
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mov zero, t8 # E : t8 is last match byte compare mask
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andnot a0, 7, v0 # E : align source addr
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or t5, t3, t3 # E : 00000000chch0000
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sll a1, 32, t2 # U : 0000chch00000000
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sll a1, 48, t4 # U : chch000000000000
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or t4, a1, a1 # E : chch00000000chch
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or t2, t3, t2 # E : 0000chchchch0000
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or a1, t2, a1 # E : chchchchchchchch
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lda t5, -1 # E : build garbage mask
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cmpbge zero, t0, t1 # E : bits set iff byte == zero
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mskqh t5, a0, t4 # E : Complete garbage mask
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xor t0, a1, t2 # E : make bytes == c zero
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cmpbge zero, t4, t4 # E : bits set iff byte is garbage
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cmpbge zero, t2, t3 # E : bits set iff byte == c
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andnot t1, t4, t1 # E : clear garbage from null test
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andnot t3, t4, t3 # E : clear garbage from char test
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bne t1, $eos # U : did we already hit the terminator?
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/* Character search main loop */
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$loop:
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ldq t0, 8(v0) # L : load next quadword
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cmovne t3, v0, t6 # E : save previous comparisons match
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nop # : Latency=2, extra map slot (keep nop with cmov)
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nop
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cmovne t3, t3, t8 # E : Latency=2, extra map slot
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nop # : keep with cmovne
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addq v0, 8, v0 # E :
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xor t0, a1, t2 # E :
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cmpbge zero, t0, t1 # E : bits set iff byte == zero
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cmpbge zero, t2, t3 # E : bits set iff byte == c
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beq t1, $loop # U : if we havnt seen a null, loop
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nop
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/* Mask out character matches after terminator */
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$eos:
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negq t1, t4 # E : isolate first null byte match
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and t1, t4, t4 # E :
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subq t4, 1, t5 # E : build a mask of the bytes upto...
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or t4, t5, t4 # E : ... and including the null
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and t3, t4, t3 # E : mask out char matches after null
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cmovne t3, t3, t8 # E : save it, if match found Latency=2, extra map slot
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nop # : Keep with cmovne
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nop
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cmovne t3, v0, t6 # E :
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nop # : Keep with cmovne
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/* Locate the address of the last matched character */
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ctlz t8, t2 # U0 : Latency=3 (0x40 for t8=0)
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nop
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cmoveq t8, 0x3f, t2 # E : Compensate for case when no match is seen
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nop # E : hide the cmov latency (2) behind ctlz latency
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lda t5, 0x3f($31) # E :
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subq t5, t2, t5 # E : Normalize leading zero count
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addq t6, t5, v0 # E : and add to quadword address
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ret # L0 : Latency=3
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nop
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nop
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END(strrchr)
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weak_alias (strrchr, rindex)
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libc_hidden_builtin_def (strrchr)
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