mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-26 15:00:06 +00:00
0aec4c1d18
Vector registers perform better than scalar register pairs for copying data so prefer them instead. This results in a time reduction of over 50% (i.e. 2x speed improvemnet) for some smaller sizes for memcpy-walk. Larger sizes show improvements of around 1% to 2%. memcpy-random shows a very small improvement, in the range of 1-2%. * sysdeps/aarch64/multiarch/memcpy_falkor.S (__memcpy_falkor): Use vector registers.
192 lines
4.5 KiB
ArmAsm
192 lines
4.5 KiB
ArmAsm
/* Optimized memcpy for Qualcomm Falkor processor.
|
|
Copyright (C) 2017-2018 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
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
#include <sysdep.h>
|
|
|
|
/* Assumptions:
|
|
|
|
ARMv8-a, AArch64, falkor, unaligned accesses. */
|
|
|
|
#define dstin x0
|
|
#define src x1
|
|
#define count x2
|
|
#define dst x3
|
|
#define srcend x4
|
|
#define dstend x5
|
|
#define tmp1 x14
|
|
#define A_x x6
|
|
#define B_x x7
|
|
#define A_w w6
|
|
#define B_w w7
|
|
|
|
#define A_q q0
|
|
#define B_q q1
|
|
#define C_q q2
|
|
#define D_q q3
|
|
#define E_q q4
|
|
#define F_q q5
|
|
#define G_q q6
|
|
|
|
/* Copies are split into 3 main cases:
|
|
|
|
1. Small copies of up to 32 bytes
|
|
2. Medium copies of 33..128 bytes which are fully unrolled
|
|
3. Large copies of more than 128 bytes.
|
|
|
|
Large copies align the sourceto a quad word and use an unrolled loop
|
|
processing 64 bytes per iteration.
|
|
|
|
FALKOR-SPECIFIC DESIGN:
|
|
|
|
The smallest copies (32 bytes or less) focus on optimal pipeline usage,
|
|
which is why the redundant copies of 0-3 bytes have been replaced with
|
|
conditionals, since the former would unnecessarily break across multiple
|
|
issue groups. The medium copy group has been enlarged to 128 bytes since
|
|
bumping up the small copies up to 32 bytes allows us to do that without
|
|
cost and also allows us to reduce the size of the prep code before loop64.
|
|
|
|
The copy loop uses only one register q0. This is to ensure that all loads
|
|
hit a single hardware prefetcher which can get correctly trained to prefetch
|
|
a single stream.
|
|
|
|
The non-temporal stores help optimize cache utilization. */
|
|
|
|
#if IS_IN (libc)
|
|
ENTRY_ALIGN (__memcpy_falkor, 6)
|
|
|
|
cmp count, 32
|
|
add srcend, src, count
|
|
add dstend, dstin, count
|
|
b.ls L(copy32)
|
|
ldr A_q, [src]
|
|
cmp count, 128
|
|
str A_q, [dstin]
|
|
b.hi L(copy_long)
|
|
|
|
/* Medium copies: 33..128 bytes. */
|
|
sub tmp1, count, 1
|
|
ldr A_q, [src, 16]
|
|
ldr B_q, [srcend, -32]
|
|
ldr C_q, [srcend, -16]
|
|
tbz tmp1, 6, 1f
|
|
ldr D_q, [src, 32]
|
|
ldr E_q, [src, 48]
|
|
str D_q, [dstin, 32]
|
|
str E_q, [dstin, 48]
|
|
ldr F_q, [srcend, -64]
|
|
ldr G_q, [srcend, -48]
|
|
str F_q, [dstend, -64]
|
|
str G_q, [dstend, -48]
|
|
1:
|
|
str A_q, [dstin, 16]
|
|
str B_q, [dstend, -32]
|
|
str C_q, [dstend, -16]
|
|
ret
|
|
|
|
.p2align 4
|
|
/* Small copies: 0..32 bytes. */
|
|
L(copy32):
|
|
/* 16-32 */
|
|
cmp count, 16
|
|
b.lo 1f
|
|
ldr A_q, [src]
|
|
ldr B_q, [srcend, -16]
|
|
str A_q, [dstin]
|
|
str B_q, [dstend, -16]
|
|
ret
|
|
.p2align 4
|
|
1:
|
|
/* 8-15 */
|
|
tbz count, 3, 1f
|
|
ldr A_x, [src]
|
|
ldr B_x, [srcend, -8]
|
|
str A_x, [dstin]
|
|
str B_x, [dstend, -8]
|
|
ret
|
|
.p2align 4
|
|
1:
|
|
/* 4-7 */
|
|
tbz count, 2, 1f
|
|
ldr A_w, [src]
|
|
ldr B_w, [srcend, -4]
|
|
str A_w, [dstin]
|
|
str B_w, [dstend, -4]
|
|
ret
|
|
.p2align 4
|
|
1:
|
|
/* 2-3 */
|
|
tbz count, 1, 1f
|
|
ldrh A_w, [src]
|
|
ldrh B_w, [srcend, -2]
|
|
strh A_w, [dstin]
|
|
strh B_w, [dstend, -2]
|
|
ret
|
|
.p2align 4
|
|
1:
|
|
/* 0-1 */
|
|
tbz count, 0, 1f
|
|
ldrb A_w, [src]
|
|
strb A_w, [dstin]
|
|
1:
|
|
ret
|
|
|
|
/* Align SRC to 16 bytes and copy; that way at least one of the
|
|
accesses is aligned throughout the copy sequence.
|
|
|
|
The count is off by 0 to 15 bytes, but this is OK because we trim
|
|
off the last 64 bytes to copy off from the end. Due to this the
|
|
loop never runs out of bounds. */
|
|
.p2align 6
|
|
L(copy_long):
|
|
sub count, count, 64 + 16
|
|
and tmp1, src, 15
|
|
bic src, src, 15
|
|
sub dst, dstin, tmp1
|
|
add count, count, tmp1
|
|
|
|
L(loop64):
|
|
ldr A_q, [src, 16]!
|
|
str A_q, [dst, 16]
|
|
ldr A_q, [src, 16]!
|
|
subs count, count, 64
|
|
str A_q, [dst, 32]
|
|
ldr A_q, [src, 16]!
|
|
str A_q, [dst, 48]
|
|
ldr A_q, [src, 16]!
|
|
str A_q, [dst, 64]!
|
|
b.hi L(loop64)
|
|
|
|
/* Write the last full set of 64 bytes. The remainder is at most 64
|
|
bytes, so it is safe to always copy 64 bytes from the end even if
|
|
there is just 1 byte left. */
|
|
L(last64):
|
|
ldr E_q, [srcend, -64]
|
|
str E_q, [dstend, -64]
|
|
ldr D_q, [srcend, -48]
|
|
str D_q, [dstend, -48]
|
|
ldr C_q, [srcend, -32]
|
|
str C_q, [dstend, -32]
|
|
ldr B_q, [srcend, -16]
|
|
str B_q, [dstend, -16]
|
|
ret
|
|
|
|
END (__memcpy_falkor)
|
|
libc_hidden_builtin_def (__memcpy_falkor)
|
|
#endif
|