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glibc/sysdeps/aarch64/multiarch/memcpy_thunderx2.S

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/* A Thunderx2 Optimized memcpy implementation for AARCH64.
Copyright (C) 2018-2024 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>
/* Assumptions:
*
* ARMv8-a, AArch64, unaligned accesses.
*
*/
#define dstin x0
#define src x1
#define count x2
#define dst x3
#define srcend x4
#define dstend x5
#define tmp2 x6
#define tmp3 x7
#define tmp3w w7
#define A_l x6
#define A_lw w6
#define A_h x7
#define A_hw w7
#define B_l x8
#define B_lw w8
#define B_h x9
#define C_l x10
#define C_h x11
#define D_l x12
#define D_h x13
#define E_l src
#define E_h count
#define F_l srcend
#define F_h dst
#define G_l count
#define G_h dst
#define tmp1 x14
#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
#define H_q q7
#define I_q q16
#define J_q q17
#define A_v v0
#define B_v v1
#define C_v v2
#define D_v v3
#define E_v v4
#define F_v v5
#define G_v v6
#define H_v v7
#define I_v v16
#define J_v v17
/* Overlapping large forward memmoves use a loop that copies backwards.
Otherwise memcpy is used. Small moves branch to memcopy16 directly.
The longer memcpy cases fall through to the memcpy head.
*/
ENTRY (__memmove_thunderx2)
PTR_ARG (0)
PTR_ARG (1)
SIZE_ARG (2)
add srcend, src, count
cmp count, 16
b.ls L(memcopy16)
sub tmp1, dstin, src
cmp count, 96
ccmp tmp1, count, 2, hi
b.lo L(move_long)
END (__memmove_thunderx2)
/* Copies are split into 3 main cases: small copies of up to 16 bytes,
medium copies of 17..96 bytes which are fully unrolled. Large copies
of more than 96 bytes align the destination and use load-and-merge
approach in the case src and dst addresses are unaligned not evenly,
so that, actual loads and stores are always aligned.
Large copies use the loops processing 64 bytes per iteration for
unaligned case and 128 bytes per iteration for aligned ones.
*/
#define MEMCPY_PREFETCH_LDR 640
ENTRY (__memcpy_thunderx2)
PTR_ARG (0)
PTR_ARG (1)
SIZE_ARG (2)
add srcend, src, count
cmp count, 16
b.ls L(memcopy16)
ldr A_q, [src], #16
add dstend, dstin, count
and tmp1, src, 15
cmp count, 96
b.hi L(memcopy_long)
/* Medium copies: 17..96 bytes. */
ldr E_q, [srcend, -16]
cmp count, 64
b.gt L(memcpy_copy96)
cmp count, 48
b.le L(bytes_17_to_48)
/* 49..64 bytes */
ldp B_q, C_q, [src]
str E_q, [dstend, -16]
stp A_q, B_q, [dstin]
str C_q, [dstin, 32]
ret
L(bytes_17_to_48):
/* 17..48 bytes*/
cmp count, 32
b.gt L(bytes_32_to_48)
/* 17..32 bytes*/
str A_q, [dstin]
str E_q, [dstend, -16]
ret
L(bytes_32_to_48):
/* 32..48 */
ldr B_q, [src]
str A_q, [dstin]
str E_q, [dstend, -16]
str B_q, [dstin, 16]
ret
.p2align 4
/* Small copies: 0..16 bytes. */
L(memcopy16):
cmp count, 8
b.lo L(bytes_0_to_8)
ldr A_l, [src]
ldr A_h, [srcend, -8]
add dstend, dstin, count
str A_l, [dstin]
str A_h, [dstend, -8]
ret
.p2align 4
L(bytes_0_to_8):
tbz count, 2, L(bytes_0_to_3)
ldr A_lw, [src]
ldr A_hw, [srcend, -4]
add dstend, dstin, count
str A_lw, [dstin]
str A_hw, [dstend, -4]
ret
/* Copy 0..3 bytes. Use a branchless sequence that copies the same
byte 3 times if count==1, or the 2nd byte twice if count==2. */
L(bytes_0_to_3):
cbz count, 1f
lsr tmp1, count, 1
ldrb A_lw, [src]
ldrb A_hw, [srcend, -1]
add dstend, dstin, count
ldrb B_lw, [src, tmp1]
strb B_lw, [dstin, tmp1]
strb A_hw, [dstend, -1]
strb A_lw, [dstin]
1:
ret
.p2align 4
L(memcpy_copy96):
/* Copying 65..96 bytes. A_q (first 16 bytes) and
E_q(last 16 bytes) are already loaded. The size
is large enough to benefit from aligned loads */
bic src, src, 15
ldp B_q, C_q, [src]
/* Loaded 64 bytes, second 16-bytes chunk can be
overlapping with the first chunk by tmp1 bytes.
Stored 16 bytes. */
sub dst, dstin, tmp1
add count, count, tmp1
/* The range of count being [65..96] becomes [65..111]
after tmp [0..15] gets added to it,
count now is <bytes-left-to-load>+48 */
cmp count, 80
b.gt L(copy96_medium)
ldr D_q, [src, 32]
stp B_q, C_q, [dst, 16]
str D_q, [dst, 48]
str A_q, [dstin]
str E_q, [dstend, -16]
ret
.p2align 4
L(copy96_medium):
ldp D_q, G_q, [src, 32]
cmp count, 96
b.gt L(copy96_large)
stp B_q, C_q, [dst, 16]
stp D_q, G_q, [dst, 48]
str A_q, [dstin]
str E_q, [dstend, -16]
ret
L(copy96_large):
ldr F_q, [src, 64]
str B_q, [dst, 16]
stp C_q, D_q, [dst, 32]
stp G_q, F_q, [dst, 64]
str A_q, [dstin]
str E_q, [dstend, -16]
ret
.p2align 4
L(memcopy_long):
bic src, src, 15
ldp B_q, C_q, [src], #32
sub dst, dstin, tmp1
add count, count, tmp1
add dst, dst, 16
and tmp1, dst, 15
ldp D_q, E_q, [src], #32
str A_q, [dstin]
/* Already loaded 64+16 bytes. Check if at
least 64 more bytes left */
subs count, count, 64+64+16
b.lt L(loop128_exit0)
cmp count, MEMCPY_PREFETCH_LDR + 64 + 32
b.lt L(loop128)
cbnz tmp1, L(dst_unaligned)
sub count, count, MEMCPY_PREFETCH_LDR + 64 + 32
.p2align 4
L(loop128_prefetch):
prfm pldl1strm, [src, MEMCPY_PREFETCH_LDR]
ldp F_q, G_q, [src], #32
stp B_q, C_q, [dst], #32
ldp H_q, I_q, [src], #32
prfm pldl1strm, [src, MEMCPY_PREFETCH_LDR]
ldp B_q, C_q, [src], #32
stp D_q, E_q, [dst], #32
ldp D_q, E_q, [src], #32
stp F_q, G_q, [dst], #32
stp H_q, I_q, [dst], #32
subs count, count, 128
b.ge L(loop128_prefetch)
add count, count, MEMCPY_PREFETCH_LDR + 64 + 32
.p2align 4
L(loop128):
ldp F_q, G_q, [src], #32
ldp H_q, I_q, [src], #32
stp B_q, C_q, [dst], #32
stp D_q, E_q, [dst], #32
subs count, count, 64
b.lt L(loop128_exit1)
ldp B_q, C_q, [src], #32
ldp D_q, E_q, [src], #32
stp F_q, G_q, [dst], #32
stp H_q, I_q, [dst], #32
subs count, count, 64
b.ge L(loop128)
L(loop128_exit0):
ldp F_q, G_q, [srcend, -64]
ldp H_q, I_q, [srcend, -32]
stp B_q, C_q, [dst], #32
stp D_q, E_q, [dst]
stp F_q, G_q, [dstend, -64]
stp H_q, I_q, [dstend, -32]
ret
L(loop128_exit1):
ldp B_q, C_q, [srcend, -64]
ldp D_q, E_q, [srcend, -32]
stp F_q, G_q, [dst], #32
stp H_q, I_q, [dst]
stp B_q, C_q, [dstend, -64]
stp D_q, E_q, [dstend, -32]
ret
L(dst_unaligned_tail):
ldp C_q, D_q, [srcend, -64]
ldp E_q, F_q, [srcend, -32]
stp A_q, B_q, [dst], #32
stp H_q, I_q, [dst], #16
str G_q, [dst, tmp1]
stp C_q, D_q, [dstend, -64]
stp E_q, F_q, [dstend, -32]
ret
L(dst_unaligned):
/* For the unaligned store case the code loads two
aligned chunks and then merges them using ext
instruction. This can be up to 30% faster than
the the simple unaligned store access.
Current state: tmp1 = dst % 16; C_q, D_q, E_q
contains data yet to be stored. src and dst points
to next-to-be-processed data. A_q, B_q contains
data already stored before, count = bytes left to
be load decremented by 64.
The control is passed here if at least 64 bytes left
to be loaded. The code does two aligned loads and then
extracts (16-tmp1) bytes from the first register and
tmp1 bytes from the next register forming the value
for the aligned store.
As ext instruction can only have it's index encoded
as immediate. 15 code chunks process each possible
index value. Computed goto is used to reach the
required code. */
/* Store the 16 bytes to dst and align dst for further
operations, several bytes will be stored at this
address once more */
ldp F_q, G_q, [src], #32
stp B_q, C_q, [dst], #32
bic dst, dst, 15
sub count, count, 32
adrp tmp2, L(ext_table)
add tmp2, tmp2, :lo12:L(ext_table)
add tmp2, tmp2, tmp1, LSL #2
ldr tmp3w, [tmp2]
add tmp2, tmp2, tmp3w, SXTW
br tmp2
.p2align 4
/* to make the loop in each chunk 16-bytes aligned */
nop
#define EXT_CHUNK(shft) \
L(ext_size_ ## shft):;\
ext A_v.16b, C_v.16b, D_v.16b, 16-shft;\
ext B_v.16b, D_v.16b, E_v.16b, 16-shft;\
ext H_v.16b, E_v.16b, F_v.16b, 16-shft;\
1:;\
stp A_q, B_q, [dst], #32;\
prfm pldl1strm, [src, MEMCPY_PREFETCH_LDR];\
ldp C_q, D_q, [src], #32;\
ext I_v.16b, F_v.16b, G_v.16b, 16-shft;\
stp H_q, I_q, [dst], #32;\
ext A_v.16b, G_v.16b, C_v.16b, 16-shft;\
ext B_v.16b, C_v.16b, D_v.16b, 16-shft;\
ldp F_q, G_q, [src], #32;\
ext H_v.16b, D_v.16b, F_v.16b, 16-shft;\
subs count, count, 64;\
b.ge 1b;\
2:;\
ext I_v.16b, F_v.16b, G_v.16b, 16-shft;\
b L(dst_unaligned_tail);
EXT_CHUNK(1)
EXT_CHUNK(2)
EXT_CHUNK(3)
EXT_CHUNK(4)
EXT_CHUNK(5)
EXT_CHUNK(6)
EXT_CHUNK(7)
EXT_CHUNK(8)
EXT_CHUNK(9)
EXT_CHUNK(10)
EXT_CHUNK(11)
EXT_CHUNK(12)
EXT_CHUNK(13)
EXT_CHUNK(14)
EXT_CHUNK(15)
L(move_long):
.p2align 4
1:
cbz tmp1, 3f
add srcend, src, count
add dstend, dstin, count
and tmp1, srcend, 15
ldr D_q, [srcend, -16]
sub srcend, srcend, tmp1
sub count, count, tmp1
ldp A_q, B_q, [srcend, -32]
str D_q, [dstend, -16]
ldp C_q, D_q, [srcend, -64]!
sub dstend, dstend, tmp1
subs count, count, 128
b.ls 2f
.p2align 4
1:
subs count, count, 64
stp A_q, B_q, [dstend, -32]
ldp A_q, B_q, [srcend, -32]
stp C_q, D_q, [dstend, -64]!
ldp C_q, D_q, [srcend, -64]!
b.hi 1b
/* 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 start even if
there is just 1 byte left. */
2:
ldp E_q, F_q, [src, 32]
ldp G_q, H_q, [src]
stp A_q, B_q, [dstend, -32]
stp C_q, D_q, [dstend, -64]
stp E_q, F_q, [dstin, 32]
stp G_q, H_q, [dstin]
3: ret
END (__memcpy_thunderx2)
.section .rodata
.p2align 4
L(ext_table):
/* The first entry is for the alignment of 0 and is never
actually used (could be any value). */
.word 0
.word L(ext_size_1) -.
.word L(ext_size_2) -.
.word L(ext_size_3) -.
.word L(ext_size_4) -.
.word L(ext_size_5) -.
.word L(ext_size_6) -.
.word L(ext_size_7) -.
.word L(ext_size_8) -.
.word L(ext_size_9) -.
.word L(ext_size_10) -.
.word L(ext_size_11) -.
.word L(ext_size_12) -.
.word L(ext_size_13) -.
.word L(ext_size_14) -.
.word L(ext_size_15) -.
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