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| author | Keith Randall <khr@golang.org> | 2016-03-06 16:58:30 -0800 |
|---|---|---|
| committer | Keith Randall <khr@golang.org> | 2016-03-21 19:10:24 +0000 |
| commit | 6a33f7765f79cf2f00f5ca55832d2cfab8beb289 (patch) | |
| tree | d1cd6a803e32d952e60290c4c863c65bd88db808 /src/runtime/memmove_amd64.s | |
| parent | b07a214d39814545bbcd1d30f1850a95752dac65 (diff) | |
| download | go-6a33f7765f79cf2f00f5ca55832d2cfab8beb289.tar.gz go-6a33f7765f79cf2f00f5ca55832d2cfab8beb289.zip | |
runtime: use MOVSB instead of MOVSQ for unaligned moves
MOVSB is quite a bit faster for unaligned moves.
Possibly we should use MOVSB all of the time, but Intel folks
say it might be a bit faster to use MOVSQ on some processors
(but not any I have access to at the moment).
benchmark old ns/op new ns/op delta
BenchmarkMemmove4096-8 93.9 93.2 -0.75%
BenchmarkMemmoveUnalignedDst4096-8 256 151 -41.02%
BenchmarkMemmoveUnalignedSrc4096-8 175 90.5 -48.29%
Fixes #14630
Change-Id: I568e6d6590eb3615e6a699fb474020596be665ff
Reviewed-on: https://go-review.googlesource.com/20293
Reviewed-by: Ian Lance Taylor <iant@golang.org>
Diffstat (limited to 'src/runtime/memmove_amd64.s')
| -rw-r--r-- | src/runtime/memmove_amd64.s | 13 |
1 files changed, 13 insertions, 0 deletions
diff --git a/src/runtime/memmove_amd64.s b/src/runtime/memmove_amd64.s index ae95b155be..514eb169f1 100644 --- a/src/runtime/memmove_amd64.s +++ b/src/runtime/memmove_amd64.s @@ -77,12 +77,25 @@ forward: CMPQ BX, $2048 JLS move_256through2048 + // Check alignment + MOVQ SI, AX + ORQ DI, AX + TESTL $7, AX + JNE unaligned_fwd + + // Aligned - do 8 bytes at a time MOVQ BX, CX SHRQ $3, CX ANDQ $7, BX REP; MOVSQ JMP tail +unaligned_fwd: + // Unaligned - do 1 byte at a time + MOVQ BX, CX + REP; MOVSB + RET + back: /* * check overlap |