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LookupFieldOrMethod appears as a hotspot when benchmarking gopls' auto-completion. In particular, instanceLookup.add was allocating in the common case of structs with no embedding. This is easily fixed, by using a small array in front of the map inside of instanceLookup. Do this, and additionally add a microbenchmark. The benchmark improvement is significant: name old time/op new time/op delta LookupFieldOrMethod-12 388µs ± 6% 154µs ± 3% -60.36% (p=0.000 n=10+10) name old alloc/op new alloc/op delta LookupFieldOrMethod-12 152kB ± 0% 2kB ± 0% -98.77% (p=0.000 n=9+10) name old allocs/op new allocs/op delta LookupFieldOrMethod-12 1.41k ± 0% 0.07k ± 0% -95.38% (p=0.000 n=10+10) It should also be noted that instanceLookup is used elsewhere, in particular by validType. In those contexts, the scope is not just the current type but the entire package, and so the newly added buffer is likely to simply cause extra Identical checks. Nevertheless, those checks are cheap, and on balance the improved LookupFieldOrMethod performance leads overall to improved type-checking performance. Standard library benchmark results varied by package, but type checking speed for many packages improved by ~5%, with allocations improved by ~10%. If this weren't the case we could let the caller control the buffer size, but that optimization doesn't seem necessary at this time. For example: Check/http/funcbodies/noinfo-12 71.5ms ± 4% 67.3ms ± 2% -5.90% (p=0.000 n=20+20) Check/http/funcbodies/noinfo-12 244k ± 0% 219k ± 0% -10.36% (p=0.000 n=19+19) Updates golang/go#53992 Change-Id: I10b6deb3819ab562dbbe1913f12b977cf956dd50 Reviewed-on: https://go-review.googlesource.com/c/go/+/423935 Run-TryBot: Robert Findley <rfindley@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Robert Griesemer <gri@google.com> |
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See src/README.vendor for information on loading vendored packages and updating the vendor directory.