[PATCH] D158689: [llvm-profdata] Use llvm::DenseMap in SampleProfileMap

[Wenlei He via Phabricator via llvm-commits]

wenlei added a comment.

> - 0.02% less instructions from the `unordered_map` version.
> - 1.2% less wall clock time from the `unordered_map` version.
>
> We didn't measure the time spent within sample profile loader though, the above numbers are all e2e compilations.

Thanks for the measurement. This result doesn't seem to justify all the trouble to remove reference stability. The benefit of DenseMap could be offset by the cost of rehashing.

> Pick the top 100 slow compilations from a major internal build target.

Among the 100 compilations measured, is there anything that shows a meaningful improvement from DenseMap?


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https://reviews.llvm.org/D158689