| commit | 77a2113925b516c0ead2ae258c4d41ac3fdc0836 | [log] [tgz] |
|---|---|---|
| author | Josh Bleecher Snyder <josharian@gmail.com> | Tue Dec 23 18:28:02 2014 -0800 |
| committer | Josh Bleecher Snyder <josharian@gmail.com> | Thu Feb 12 22:23:38 2015 +0000 |
| tree | 9dce58ccff89194921957f0023c9c35a784cea29 | |
| parent | 747c8498339b799eb613db1701a927a3549d389a [diff] |
cmd/gc: evaluate concrete == interface without allocating Consider an interface value i of type I and concrete value c of type C. Prior to this CL, i==c was evaluated as I(c) == i Evaluating I(c) can allocate. This CL changes the evaluation of i==c to x, ok := i.(C); ok && x == c The new generated code is shorter and does not allocate directly. If C is small, as it is in every instance in the stdlib, the new code also uses less stack space and makes one runtime call instead of two. If C is very large, the original implementation is used. The cutoff for "very large" is 1<<16, following the stack vs heap cutoff used elsewhere. This kind of comparison occurs in 38 places in the stdlib, mostly in the net and os packages. benchmark old ns/op new ns/op delta BenchmarkEqEfaceConcrete 29.5 7.92 -73.15% BenchmarkEqIfaceConcrete 32.1 7.90 -75.39% BenchmarkNeEfaceConcrete 29.9 7.90 -73.58% BenchmarkNeIfaceConcrete 35.9 7.90 -77.99% Fixes #9370. Change-Id: I7c4555950bcd6406ee5c613be1f2128da2c9a2b7 Reviewed-on: https://go-review.googlesource.com/2096 Reviewed-by: Russ Cox <rsc@golang.org> Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
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