| commit | f03c9202c43e0abb130669852082117ca50aa9b1 | [log] [tgz] |
|---|---|---|
| author | Josh Bleecher Snyder <josharian@gmail.com> | Wed Jan 07 17:44:49 2015 -0800 |
| committer | Josh Bleecher Snyder <josharian@gmail.com> | Fri Jan 09 22:35:25 2015 +0000 |
| tree | bb8f7c8026fbbd79231e5e6ea108d2d1a380cecc | |
| parent | 1d0c7792f172ab0485edf2818398deffe3d452ba [diff] |
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>
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