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crypto/sha1: Optimise FUNC1 with alternate formulation

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According to Wikipedia: http://en.wikipedia.org/wiki/SHA-1
there is an alternate formulation for the FUNC1 transform,
namely

f1 = d xor (b and (c xor d))

instead of

f1 = (b and c) or ((not b) and d)

This reduces the instruction count of FUNC1 from 6 to 4 and
makes about 5% speed improvement on amd64 and suprisingly 17%
on 386.

amd64 Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz:

benchmark              old ns/op    new ns/op    delta
BenchmarkHash8Bytes          506          499   -1.38%
BenchmarkHash1K             3099         2961   -4.45%
BenchmarkHash8K            22292        21243   -4.71%

benchmark               old MB/s     new MB/s  speedup
BenchmarkHash8Bytes        15.80        16.00    1.01x
BenchmarkHash1K           330.40       345.82    1.05x
BenchmarkHash8K           367.48       385.63    1.05x

i386 Intel(R) Core(TM) i7 CPU Q 820 @ 1.73GHz:

benchmark              old ns/op    new ns/op    delta
BenchmarkHash8Bytes          647          615   -4.95%
BenchmarkHash1K             3673         3161  -13.94%
BenchmarkHash8K            26141        22374  -14.41%

benchmark               old MB/s     new MB/s  speedup
BenchmarkHash8Bytes        12.35        13.01    1.05x
BenchmarkHash1K           278.74       323.94    1.16x
BenchmarkHash8K           313.37       366.13    1.17x

The improvements on an Intel(R) Core(TM) i7-4770K CPU @
3.50GHz were almost identical.

R=golang-dev, r, hanwen
CC=golang-dev, rsc
https://golang.org/cl/19910043
This commit is contained in:
Nick Craig-Wood 2013-12-12 11:26:36 -08:00 committed by Rob Pike
parent e5902fc70f
commit 107d18299c
2 changed files with 8 additions and 12 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

10
src/pkg/crypto/sha1/sha1block_386.s
View File

@ -46,12 +46,10 @@
ADDL DI, e
#define FUNC1(a, b, c, d, e) \
MOVL b, SI; \
ANDL c, SI; \
MOVL b, DI; \
NOTL DI; \
ANDL d, DI; \
ORL SI, DI
MOVL d, DI; \
XORL c, DI; \
ANDL b, DI; \
XORL d, DI
#define FUNC2(a, b, c, d, e) \
MOVL b, DI; \

10
src/pkg/crypto/sha1/sha1block_amd64.s
View File

@ -34,12 +34,10 @@
MOVL R10, (((index)&0xf)*4)(SP)
#define FUNC1(a, b, c, d, e) \
MOVL b, R8; \
ANDL c, R8; \
MOVL b, R9; \
NOTL R9; \
ANDL d, R9; \
ORL R8, R9
MOVL d, R9; \
XORL c, R9; \
ANDL b, R9; \
XORL d, R9
#define FUNC2(a, b, c, d, e) \
MOVL b, R9; \