aarch64,falkor: Use vector registers for memmove

Vector registers perform much better for moves compared to pairs of
registers on falkor, so use them instead.  This results in a time
reduction of up to 50% (i.e. 2x improvement) for a lot of the smaller
sizes, i.e. up to 1K in memmove-walk.  Improvements for larger sizes are
smaller, at about 1%-2%.

	* sysdeps/aarch64/multiarch/memmove_falkor.S
	(__memcpy_falkor): Use vector registers.
This commit is contained in:
Siddhesh Poyarekar 2018-06-29 22:45:07 +05:30
parent 7e8989d03b
commit ce76a5cb8d
2 changed files with 93 additions and 105 deletions

View File

@ -1,3 +1,8 @@
2018-06-29 Siddhesh Poyarekar <siddhesh@sourceware.org>
* sysdeps/aarch64/multiarch/memmove_falkor.S
(__memcpy_falkor): Use vector registers.
2018-06-29 Martin Sebor <msebor@redhat.com>
* manual/stdio.texi (Customizing Printf): Mention interaction

View File

@ -23,44 +23,36 @@
#define dstin x0
#define src x1
#define count x2
#define dstlen x3
#define dst x3
#define srcend x4
#define dstend x5
#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 A_x x6
#define B_x x7
#define A_w w6
#define B_w w7
#define tmp1 x14
/* Alias with A_l and A_h to train the prefetcher. */
#define Q_l x22
#define Q_h x23
#define Q_q q6
#define A_q q22
#define B_q q18
#define C_q q19
#define D_q q20
#define E_q q21
#define F_q q17
#define G_q q23
/* RATIONALE:
The copy has 4 distinct parts:
* Small copies of 16 bytes and under
* Medium sized copies of 17-96 bytes
* Large copies where the source address is higher than the destination
The move has 4 distinct parts:
* Small moves of 16 bytes and under
* Medium sized moves of 17-96 bytes
* Large moves where the source address is higher than the destination
(forward copies)
* Large copies where the destination address is higher than the source
* Large moves where the destination address is higher than the source
(copy backward, or move).
We use only two registerpairs x6,x7 and x22,x23 for the copies and copy 32
bytes at a time to correctly train the hardware prefetcher for better
throughput. */
We use only two registers q6 and q22 for the moves and move 32 bytes at a
time to correctly train the hardware prefetcher for better throughput. */
ENTRY_ALIGN (__memmove_falkor, 6)
sub tmp1, dstin, src
@ -77,17 +69,17 @@ ENTRY_ALIGN (__memmove_falkor, 6)
/* Medium copies: 17..96 bytes. */
sub tmp1, count, 1
ldp A_l, A_h, [src]
ldr A_q, [src]
tbnz tmp1, 6, L(copy96)
ldp D_l, D_h, [srcend, -16]
ldr D_q, [srcend, -16]
tbz tmp1, 5, 1f
ldp B_l, B_h, [src, 16]
ldp C_l, C_h, [srcend, -32]
stp B_l, B_h, [dstin, 16]
stp C_l, C_h, [dstend, -32]
ldr B_q, [src, 16]
ldr C_q, [srcend, -32]
str B_q, [dstin, 16]
str C_q, [dstend, -32]
1:
stp A_l, A_h, [dstin]
stp D_l, D_h, [dstend, -16]
str A_q, [dstin]
str D_q, [dstend, -16]
ret
.p2align 4
@ -95,52 +87,52 @@ ENTRY_ALIGN (__memmove_falkor, 6)
L(copy16):
cmp count, 8
b.lo 1f
ldr A_l, [src]
ldr A_h, [srcend, -8]
str A_l, [dstin]
str A_h, [dstend, -8]
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_lw, [src]
ldr A_hw, [srcend, -4]
str A_lw, [dstin]
str A_hw, [dstend, -4]
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_lw, [src]
ldrh A_hw, [srcend, -2]
strh A_lw, [dstin]
strh A_hw, [dstend, -2]
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_lw, [src]
strb A_lw, [dstin]
ldrb A_w, [src]
strb A_w, [dstin]
1: ret
.p2align 4
/* Copy 64..96 bytes. Copy 64 bytes from the start and
32 bytes from the end. */
L(copy96):
ldp B_l, B_h, [src, 16]
ldp C_l, C_h, [src, 32]
ldp D_l, D_h, [src, 48]
ldp E_l, E_h, [srcend, -32]
ldp F_l, F_h, [srcend, -16]
stp A_l, A_h, [dstin]
stp B_l, B_h, [dstin, 16]
stp C_l, C_h, [dstin, 32]
stp D_l, D_h, [dstin, 48]
stp E_l, E_h, [dstend, -32]
stp F_l, F_h, [dstend, -16]
ldr B_q, [src, 16]
ldr C_q, [src, 32]
ldr D_q, [src, 48]
ldr E_q, [srcend, -32]
ldr F_q, [srcend, -16]
str A_q, [dstin]
str B_q, [dstin, 16]
str C_q, [dstin, 32]
str D_q, [dstin, 48]
str E_q, [dstend, -32]
str F_q, [dstend, -16]
ret
/* Align SRC to 16 byte alignment so that we don't cross cache line
@ -150,92 +142,83 @@ L(copy96):
.p2align 4
L(copy_long):
mov B_l, Q_l
mov B_h, Q_h
ldp A_l, A_h, [src]
ldr A_q, [src]
and tmp1, src, 15
bic src, src, 15
sub dst, dstin, tmp1
add count, count, tmp1 /* Count is now 16 too large. */
ldp Q_l, Q_h, [src, 16]!
stp A_l, A_h, [dstin]
ldp A_l, A_h, [src, 16]!
ldr Q_q, [src, 16]!
str A_q, [dstin]
ldr A_q, [src, 16]!
subs count, count, 32 + 64 + 16 /* Test and readjust count. */
b.ls L(last64)
L(loop64):
subs count, count, 32
stp Q_l, Q_h, [dst, 16]
ldp Q_l, Q_h, [src, 16]!
stp A_l, A_h, [dst, 32]!
ldp A_l, A_h, [src, 16]!
str Q_q, [dst, 16]
ldr Q_q, [src, 16]!
str A_q, [dst, 32]!
ldr A_q, [src, 16]!
b.hi L(loop64)
/* Write the last full set of 64 bytes. The remainder is at most 64
bytes and at least 33 bytes, so it is safe to always copy 64 bytes
from the end. */
L(last64):
ldp C_l, C_h, [srcend, -64]
stp Q_l, Q_h, [dst, 16]
mov Q_l, B_l
mov Q_h, B_h
ldp B_l, B_h, [srcend, -48]
stp A_l, A_h, [dst, 32]
ldp A_l, A_h, [srcend, -32]
ldp D_l, D_h, [srcend, -16]
stp C_l, C_h, [dstend, -64]
stp B_l, B_h, [dstend, -48]
stp A_l, A_h, [dstend, -32]
stp D_l, D_h, [dstend, -16]
ldr C_q, [srcend, -64]
str Q_q, [dst, 16]
ldr B_q, [srcend, -48]
str A_q, [dst, 32]
ldr A_q, [srcend, -32]
ldr D_q, [srcend, -16]
str C_q, [dstend, -64]
str B_q, [dstend, -48]
str A_q, [dstend, -32]
str D_q, [dstend, -16]
ret
.p2align 4
L(move_long):
cbz tmp1, 3f
mov B_l, Q_l
mov B_h, Q_h
/* Align SRCEND to 16 byte alignment so that we don't cross cache line
boundaries on both loads and stores. There are at least 96 bytes
to copy, so copy 16 bytes unaligned and then align. The loop
copies 32 bytes per iteration and prefetches one iteration ahead. */
ldp A_l, A_h, [srcend, -16]
ldr A_q, [srcend, -16]
and tmp1, srcend, 15
sub srcend, srcend, tmp1
ldp Q_l, Q_h, [srcend, -16]!
stp A_l, A_h, [dstend, -16]
ldr Q_q, [srcend, -16]!
str A_q, [dstend, -16]
sub count, count, tmp1
ldp A_l, A_h, [srcend, -16]!
ldr A_q, [srcend, -16]!
sub dstend, dstend, tmp1
subs count, count, 32 + 64
b.ls 2f
1:
subs count, count, 32
stp Q_l, Q_h, [dstend, -16]
ldp Q_l, Q_h, [srcend, -16]!
stp A_l, A_h, [dstend, -32]!
ldp A_l, A_h, [srcend, -16]!
str Q_q, [dstend, -16]
ldr Q_q, [srcend, -16]!
str A_q, [dstend, -32]!
ldr A_q, [srcend, -16]!
b.hi 1b
/* Write the last full set of 64 bytes. The remainder is at most 64
bytes and at least 33 bytes, so it is safe to always copy 64 bytes
from the start. */
2:
ldp C_l, C_h, [src, 48]
stp Q_l, Q_h, [dstend, -16]
mov Q_l, B_l
mov Q_h, B_h
ldp B_l, B_h, [src, 32]
stp A_l, A_h, [dstend, -32]
ldp A_l, A_h, [src, 16]
ldp D_l, D_h, [src]
stp C_l, C_h, [dstin, 48]
stp B_l, B_h, [dstin, 32]
stp A_l, A_h, [dstin, 16]
stp D_l, D_h, [dstin]
ldr C_q, [src, 48]
str Q_q, [dstend, -16]
ldr B_q, [src, 32]
str A_q, [dstend, -32]
ldr A_q, [src, 16]
ldr D_q, [src]
str C_q, [dstin, 48]
str B_q, [dstin, 32]
str A_q, [dstin, 16]
str D_q, [dstin]
3: ret
END (__memmove_falkor)