TrueCloudLab/tzhash
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Replace two shifts with a single AND

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We need to isolate HSB in every quad-word, this can be done with a
simple mask.

Signed-off-by: Evgenii Stratonikov <evgeniy@nspcc.ru>
This commit is contained in:
Evgenii Stratonikov 2021-12-29 14:49:20 +03:00 committed by Alex Vanin
parent a7201418ab
commit d4cb61e470
1 changed files with 5 additions and 4 deletions
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9
tz/avx2_amd64.s
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@ -10,8 +10,7 @@
VPALIGNR $8, Y1, Y0, Y2 \
VPSRLQ $63, Y2, Y2 \
VPXOR Y1, Y2, Y2 \
VPSRLQ $63, Y1, Y3 \
VPSLLQ $63, Y3, Y3 \
VPAND Y1, Y14, Y3 \
VPUNPCKHQDQ Y3, Y3, Y3 \
VPXOR Y2, Y3, Y3 \
mask(bit, Y11, Y2) \
@ -28,8 +27,10 @@ TEXT ·mulByteRightx2(SB),NOSPLIT,$0
VMOVDQU (BX), Y8
VPXOR Y13, Y13, Y13 // Y13 = 0x0000...
VPCMPEQB Y12, Y12, Y12 // Y12 = 0xFFFF...
VPSUBW Y12, Y13, Y12 // Y12 = 0x00010001... (packed words of 1)
VPCMPEQB Y14, Y14, Y14 // Y14 = 0xFFFF...
VPSUBQ Y14, Y13, Y10
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.
VPMOVZXBW X10, Y10 // Extend with zeroes to packed words.