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Rewrite AVX2 loop in assembly

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Helps to get rid of MOV and generating constants for each iteration.

```
name                     old time/op    new time/op    delta
Sum/AVX2Inline_digest-8    1.57ms ± 2%    1.41ms ± 0%  -10.52%  (p=0.000 n=9+9)

name                     old speed      new speed      delta
Sum/AVX2Inline_digest-8  63.6MB/s ± 1%  71.1MB/s ± 0%  +11.76%  (p=0.000 n=9+9)
```

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
This commit is contained in:
Evgenii Stratonikov 2022-01-10 18:01:15 +03:00 committed by Alex Vanin
parent d7c96f5d2e
commit 73d978c31e
2 changed files with 18 additions and 6 deletions
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18
tz/avx2_amd64.s
View file

@ -18,8 +18,8 @@
VPAND out_1, Y2, Y4 \
VPXOR Y4, in_1, out_2 \
// func mulByteRightx2(c00c10, c01c11 *[4]uint64, b byte)
TEXT ·mulByteRightx2(SB),NOSPLIT,$0
// func mulByteSliceRightx2(c00c10, c01c11 *[4]uint64, n int, data *byte)
TEXT ·mulByteSliceRightx2(SB),NOSPLIT,$0
MOVQ c00c10+0(FP), AX
VMOVDQU (AX), Y0
MOVQ c01c11+8(FP), BX
@ -31,8 +31,17 @@ TEXT ·mulByteRightx2(SB),NOSPLIT,$0
VPSUBW Y14, Y13, Y12 // Y12 = 0x00010001... (packed words of 1)
VPSLLQ $63, Y10, Y14 // Y14 = 0x10000000... (packed quad-words with HSB set)
VPBROADCASTB b+16(FP), X10 // X10 = packed bytes of b.
MOVQ n+16(FP), CX
MOVQ data+24(FP), DX
loop:
CMPQ CX, $0
JEQ finish
SUBQ $1, CX
VPBROADCASTB (DX), X10 // X10 = packed bytes of b.
VPMOVZXBW X10, Y10 // Extend with zeroes to packed words.
ADDQ $1, DX
mulBit($7, Y0, Y8, Y5, Y6)
mulBit($6, Y5, Y6, Y0, Y8)
@ -43,6 +52,9 @@ TEXT ·mulByteRightx2(SB),NOSPLIT,$0
mulBit($1, Y0, Y8, Y5, Y6)
mulBit($0, Y5, Y6, Y0, Y8)
JMP loop
finish:
VMOVDQU Y8, (BX)
VMOVDQU Y0, (AX)

6
tz/avx2_inline.go
View file

@ -25,8 +25,8 @@ func newAVX2Inline() *digest3 {
func (d *digest3) Write(data []byte) (n int, err error) {
n = len(data)
for _, b := range data {
mulByteRightx2(&d.x[0], &d.x[1], b)
if len(data) != 0 {
mulByteSliceRightx2(&d.x[0], &d.x[1], n, &data[0])
}
return
}
@ -56,4 +56,4 @@ func (d *digest3) checkSum() (b [hashSize]byte) {
return
}
func mulByteRightx2(c00c10 *avx2.GF127x2, c01c11 *avx2.GF127x2, b byte)
func mulByteSliceRightx2(c00c10 *avx2.GF127x2, c01c11 *avx2.GF127x2, n int, data *byte)