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math/big: implement addMulVVW on arm64 

The lack of proper addMulVVW implementation for arm64 hurts RSA performance.

This assembly implementation is optimized for arm64 based servers.

name                  old time/op    new time/op     delta
pkg:math/big goos:linux goarch:arm64
AddMulVVW/1             55.2ns ± 0%     11.9ns ± 1%    -78.37%  (p=0.000 n=8+10)
AddMulVVW/2             67.0ns ± 0%     11.2ns ± 0%    -83.28%  (p=0.000 n=7+10)
AddMulVVW/3             93.2ns ± 0%     13.2ns ± 0%    -85.84%  (p=0.000 n=10+10)
AddMulVVW/4              126ns ± 0%       13ns ± 1%    -89.82%  (p=0.000 n=10+10)
AddMulVVW/5              151ns ± 0%       17ns ± 0%    -88.87%  (p=0.000 n=10+9)
AddMulVVW/10             323ns ± 0%       25ns ± 0%    -92.20%  (p=0.000 n=10+10)
AddMulVVW/100           3.28µs ± 0%     0.14µs ± 0%    -95.82%  (p=0.000 n=10+10)
AddMulVVW/1000          31.7µs ± 0%      1.3µs ± 0%    -96.00%  (p=0.000 n=10+8)
AddMulVVW/10000          313µs ± 0%       13µs ± 0%    -95.98%  (p=0.000 n=10+10)
AddMulVVW/100000        3.24ms ± 0%     0.13ms ± 1%    -96.13%  (p=0.000 n=9+9)
pkg:crypto/rsa goos:linux goarch:arm64
RSA2048Decrypt          44.7ms ± 0%      4.0ms ± 6%    -91.08%  (p=0.000 n=8+10)
RSA2048Sign             46.3ms ± 0%      5.0ms ± 0%    -89.29%  (p=0.000 n=9+10)
3PrimeRSA2048Decrypt    22.3ms ± 0%      2.4ms ± 0%    -89.26%  (p=0.000 n=10+10)

Change-Id: I295f0bd5c51a4442d02c44ece1f6026d30dff0bc
Reviewed-on: https://go-review.googlesource.com/76270
Reviewed-by: Vlad Krasnov <vlad@cloudflare.com>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Vlad Krasnov <vlad@cloudflare.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Vlad Krasnov 2017-11-06 13:59:51 -08:00 committed by Cherry Zhang
parent b1335037fa
commit fd3d27938a
1 changed files with 82 additions and 1 deletions
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83
src/math/big/arith_arm64.s
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@ -199,8 +199,89 @@ done:
// func addMulVVW(z, x []Word, y Word) (c Word)
TEXT ·addMulVVW(SB),NOSPLIT,$0
B ·addMulVVW_g(SB)
MOVD z+0(FP), R1
MOVD z_len+8(FP), R0
MOVD x+24(FP), R2
MOVD y+48(FP), R3
MOVD $0, R4
TBZ $0, R0, two
MOVD.P 8(R2), R5
MOVD (R1), R6
MUL R5, R3, R7
UMULH R5, R3, R8
ADDS R7, R6
ADC $0, R8, R4
MOVD.P R6, 8(R1)
SUB $1, R0
two:
TBZ $1, R0, loop
LDP.P 16(R2), (R5, R10)
LDP (R1), (R6, R11)
MUL R10, R3, R13
UMULH R10, R3, R12
MUL R5, R3, R7
UMULH R5, R3, R8
ADDS R4, R6
ADCS R13, R11
ADC $0, R12
ADDS R7, R6
ADCS R8, R11
ADC $0, R12, R4
STP.P (R6, R11), 16(R1)
SUB $2, R0
// The main loop of this code operates on a block of 4 words every iteration
// performing [R4:R12:R11:R10:R9] = R4 + R3 * [R8:R7:R6:R5] + [R12:R11:R10:R9]
// where R4 is carried from the previous iteration, R8:R7:R6:R5 hold the next
// 4 words of x, R3 is y and R12:R11:R10:R9 are part of the result z.
loop:
CBZ R0, done
LDP.P 16(R2), (R5, R6)
LDP.P 16(R2), (R7, R8)
LDP (R1), (R9, R10)
ADDS R4, R9
MUL R6, R3, R14
ADCS R14, R10
MUL R7, R3, R15
LDP 16(R1), (R11, R12)
ADCS R15, R11
MUL R8, R3, R16
ADCS R16, R12
UMULH R8, R3, R20
ADC $0, R20
MUL R5, R3, R13
ADDS R13, R9
UMULH R5, R3, R17
ADCS R17, R10
UMULH R6, R3, R21
STP.P (R9, R10), 16(R1)
ADCS R21, R11
UMULH R7, R3, R19
ADCS R19, R12
STP.P (R11, R12), 16(R1)
ADC $0, R20, R4
SUB $4, R0
B loop
done:
MOVD R4, c+56(FP)
RET
// func divWVW(z []Word, xn Word, x []Word, y Word) (r Word)
TEXT ·divWVW(SB),NOSPLIT,$0