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/* Optimized memmove implementation for POWER10.
Copyright (C) 2021-2024 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <sysdep.h>
/* void* [r3] memmove (void *dest [r3], const void *src [r4], size_t len [r5])
This optimization checks if 'src' and 'dst' overlap. If they do not
or 'src' is ahead of 'dest' then it copies forward.
Otherwise, an optimized backward copy is used. */
#ifndef MEMMOVE
# define MEMMOVE memmove
#endif
.machine power9
ENTRY_TOCLESS (MEMMOVE, 5)
CALL_MCOUNT 3
L(_memmove):
.p2align 5
/* Check if there is overlap, if so it will branch to backward copy. */
subf r9,r4,r3
cmpld cr7,r9,r5
blt cr7,L(memmove_bwd)
/* Fast path for length shorter than 16 bytes. */
sldi r7,r5,56
lxvl 32+v2,r4,r7
stxvl 32+v2,r3,r7
subic. r8,r5,16
blelr
/* For shorter lengths aligning the dest address to 16 bytes either
decreases performance or is irrelevant. I'm making use of this
comparison to skip the alignment in. */
cmpldi cr6,r5,256
bge cr6,L(ge_256)
/* Account for the first 16-byte copy. */
addi r4,r4,16
addi r11,r3,16 /* use r11 to keep dest address on r3. */
subi r5,r5,16
b L(loop_head)
.p2align 5
L(ge_256):
/* Account for the first copy <= 16 bytes. This is necessary for
memmove because at this point the src address can be in front of the
dest address. */
clrldi r9,r5,56
li r8,16
cmpldi r9,16
iselgt r9,r8,r9
add r4,r4,r9
add r11,r3,r9 /* use r11 to keep dest address on r3. */
sub r5,r5,r9
/* Align dest to 16 bytes. */
neg r7,r3
clrldi. r9,r7,60
beq L(loop_head)
.p2align 5
sldi r6,r9,56
lxvl 32+v0,r4,r6
stxvl 32+v0,r11,r6
sub r5,r5,r9
add r4,r4,r9
add r11,r11,r9
L(loop_head):
cmpldi r5,63
ble L(final_64)
srdi. r7,r5,7
beq L(loop_tail)
mtctr r7
/* Main loop that copies 128 bytes each iteration. */
.p2align 5
L(loop):
addi r9,r4,64
addi r10,r11,64
lxv 32+v0,0(r4)
lxv 32+v1,16(r4)
lxv 32+v2,32(r4)
lxv 32+v3,48(r4)
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
stxv 32+v2,32(r11)
stxv 32+v3,48(r11)
addi r4,r4,128
addi r11,r11,128
lxv 32+v4,0(r9)
lxv 32+v5,16(r9)
lxv 32+v6,32(r9)
lxv 32+v7,48(r9)
stxv 32+v4,0(r10)
stxv 32+v5,16(r10)
stxv 32+v6,32(r10)
stxv 32+v7,48(r10)
bdnz L(loop)
clrldi. r5,r5,57
beqlr
/* Copy 64 bytes. */
.p2align 5
L(loop_tail):
cmpldi cr5,r5,63
ble cr5,L(final_64)
lxv 32+v0,0(r4)
lxv 32+v1,16(r4)
lxv 32+v2,32(r4)
lxv 32+v3,48(r4)
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
stxv 32+v2,32(r11)
stxv 32+v3,48(r11)
addi r4,r4,64
addi r11,r11,64
subi r5,r5,64
/* Copies the last 1-63 bytes. */
.p2align 5
L(final_64):
/* r8 holds the number of bytes that will be copied with lxv/stxv. */
clrrdi. r8,r5,4
beq L(tail1)
cmpldi cr5,r5,32
lxv 32+v0,0(r4)
blt cr5,L(tail2)
cmpldi cr6,r5,48
lxv 32+v1,16(r4)
blt cr6,L(tail3)
.p2align 5
lxv 32+v2,32(r4)
stxv 32+v2,32(r11)
L(tail3):
stxv 32+v1,16(r11)
L(tail2):
stxv 32+v0,0(r11)
sub r5,r5,r8
add r4,r4,r8
add r11,r11,r8
.p2align 5
L(tail1):
sldi r6,r5,56
lxvl v4,r4,r6
stxvl v4,r11,r6
blr
/* If dest and src overlap, we should copy backwards. */
L(memmove_bwd):
add r11,r3,r5
add r4,r4,r5
/* Optimization for length smaller than 16 bytes. */
cmpldi cr5,r5,15
ble cr5,L(tail1_bwd)
/* For shorter lengths the alignment either slows down or is irrelevant.
The forward copy uses a already need 256 comparison for that. Here
it's using 128 as it will reduce code and improve readability. */
cmpldi cr7,r5,128
blt cr7,L(bwd_loop_tail)
/* Align dest address to 16 bytes. */
.p2align 5
clrldi. r9,r11,60
beq L(bwd_loop_head)
sub r4,r4,r9
sub r11,r11,r9
lxv 32+v0,0(r4)
sldi r6,r9,56
stxvl 32+v0,r11,r6
sub r5,r5,r9
L(bwd_loop_head):
srdi. r7,r5,7
beq L(bwd_loop_tail)
mtctr r7
/* Main loop that copies 128 bytes every iteration. */
.p2align 5
L(bwd_loop):
addi r9,r4,-64
addi r10,r11,-64
lxv 32+v0,-16(r4)
lxv 32+v1,-32(r4)
lxv 32+v2,-48(r4)
lxv 32+v3,-64(r4)
stxv 32+v0,-16(r11)
stxv 32+v1,-32(r11)
stxv 32+v2,-48(r11)
stxv 32+v3,-64(r11)
addi r4,r4,-128
addi r11,r11,-128
lxv 32+v0,-16(r9)
lxv 32+v1,-32(r9)
lxv 32+v2,-48(r9)
lxv 32+v3,-64(r9)
stxv 32+v0,-16(r10)
stxv 32+v1,-32(r10)
stxv 32+v2,-48(r10)
stxv 32+v3,-64(r10)
bdnz L(bwd_loop)
clrldi. r5,r5,57
beqlr
/* Copy 64 bytes. */
.p2align 5
L(bwd_loop_tail):
cmpldi cr5,r5,63
ble cr5,L(bwd_final_64)
addi r4,r4,-64
addi r11,r11,-64
lxv 32+v0,0(r4)
lxv 32+v1,16(r4)
lxv 32+v2,32(r4)
lxv 32+v3,48(r4)
stxv 32+v0,0(r11)
stxv 32+v1,16(r11)
stxv 32+v2,32(r11)
stxv 32+v3,48(r11)
subi r5,r5,64
/* Copies the last 1-63 bytes. */
.p2align 5
L(bwd_final_64):
/* r8 holds the number of bytes that will be copied with lxv/stxv. */
clrrdi. r8,r5,4
beq L(tail1_bwd)
cmpldi cr5,r5,32
lxv 32+v2,-16(r4)
blt cr5,L(tail2_bwd)
cmpldi cr6,r5,48
lxv 32+v1,-32(r4)
blt cr6,L(tail3_bwd)
.p2align 5
lxv 32+v0,-48(r4)
stxv 32+v0,-48(r11)
L(tail3_bwd):
stxv 32+v1,-32(r11)
L(tail2_bwd):
stxv 32+v2,-16(r11)
sub r4,r4,r5
sub r11,r11,r5
sub r5,r5,r8
sldi r6,r5,56
lxvl v4,r4,r6
stxvl v4,r11,r6
blr
/* Copy last 16 bytes. */
.p2align 5
L(tail1_bwd):
sub r4,r4,r5
sub r11,r11,r5
sldi r6,r5,56
lxvl v4,r4,r6
stxvl v4,r11,r6
blr
END_GEN_TB (MEMMOVE,TB_TOCLESS)
libc_hidden_builtin_def (memmove)
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