| commit | ab2f83c387fcc00efbdcc0a5c249af26c84ff425 | [log] [tgz] |
|---|---|---|
| author | Daniel Martí <mvdan@mvdan.cc> | Fri Apr 05 23:06:49 2019 +0200 |
| committer | Daniel Martí <mvdan@mvdan.cc> | Sat Apr 13 13:14:55 2019 +0000 |
| tree | caf7b2db1bac258864516cdb1f32c16be7603a78 | |
| parent | ee64b35531a841ab4dbe41c17390214f9dea654f [diff] |
encoding/json: remove a bounds check in readValue readValue is a hot function, clocking in at ~13% flat CPU use in CodeDecoder. In particular, looping over the bytes is slow. That's partially because the code contains a bounds check at the start of the loop. The source of the problem is that scanp is a signed integer, and comes from a field, so the compiler doesn't know that it's non-negative. Help it with a simple and comparatively cheap hint. While at it, use scanp as the index variable directly, removing the need for a duplicate index variable which is later added back into scanp. name old time/op new time/op delta CodeDecoder-8 11.3ms ± 1% 11.2ms ± 1% -0.98% (p=0.000 n=9+9) name old speed new speed delta CodeDecoder-8 172MB/s ± 1% 174MB/s ± 1% +0.99% (p=0.000 n=9+9) Updates #28923. Change-Id: I138f83babdf316fc97697cc18f595c3403c1ddb7 Reviewed-on: https://go-review.googlesource.com/c/go/+/170939 Run-TryBot: Daniel Martí <mvdan@mvdan.cc> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
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