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2 Commits

Author SHA1 Message Date
Josh Bleecher Snyder
f03c9202c4 cmd/gc: optimize memclr of slices and arrays
Recognize loops of the form

for i := range a {
	a[i] = zero
}

in which the evaluation of a is free from side effects.
Replace these loops with calls to memclr.
This occurs in the stdlib in 18 places.

The motivating example is clearing a byte slice:

benchmark                old ns/op     new ns/op     delta
BenchmarkGoMemclr5       3.31          3.26          -1.51%
BenchmarkGoMemclr16      13.7          3.28          -76.06%
BenchmarkGoMemclr64      50.8          4.14          -91.85%
BenchmarkGoMemclr256     157           6.02          -96.17%

Update #5373.

Change-Id: I99d3e6f5f268e8c6499b7e661df46403e5eb83e4
Reviewed-on: https://go-review.googlesource.com/2520
Reviewed-by: Keith Randall <khr@golang.org>
2015-01-09 22:35:25 +00:00
Russ Cox
c007ce824d build: move package sources from src/pkg to src
Preparation was in CL 134570043.
This CL contains only the effect of 'hg mv src/pkg/* src'.
For more about the move, see golang.org/s/go14nopkg.
2014-09-08 00:08:51 -04:00