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Optimize equality comparison of two empty string_views #4904

Merged
merged 7 commits into from
Aug 25, 2024
Merged

Optimize equality comparison of two empty string_views #4904

merged 7 commits into from
Aug 25, 2024

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YexuanXiao
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@YexuanXiao YexuanXiao commented Aug 22, 2024 •
edited by CaseyCarter
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Fixes #3310.

@YexuanXiao YexuanXiao requested a review from a team as a code owner August 22, 2024 18:49
@CaseyCarter CaseyCarter added the performance Must go faster label Aug 22, 2024
@StephanTLavavej StephanTLavavej self-assigned this Aug 22, 2024
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CaseyCarter approved these changes Aug 22, 2024
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Some minor nits that I'll apply.

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@CaseyCarter CaseyCarter mentioned this pull request Aug 22, 2024
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@StephanTLavavej StephanTLavavej changed the title Optimize equality comparison of two empty string_views (#3310) Optimize equality comparison of two empty string_views Aug 23, 2024
@StephanTLavavej StephanTLavavej removed their assignment Aug 23, 2024
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Thanks, this is great! 😻 I pushed a commit for trivial naming nitpicks, and verified that there's a significant speedup for empty comparisons (I observed 1.7x, from 37.4 ns down to 22.0 ns).

We merge PRs to our GitHub and MSVC-internal repos simultaneously in a semi-manual process, batched up to save time. Your PR will be part of the next batch. I'll post comments here as I prepare this for merging!

@StephanTLavavej StephanTLavavej self-assigned this Aug 25, 2024
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I'm mirroring this to the MSVC-internal repo - please notify me if any further changes are pushed.

@StephanTLavavej StephanTLavavej merged commit d1f63f3 into microsoft:main Aug 25, 2024
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Thanks for this significant performance improvement - it's a small change but it affects extremely common operations (both string and string_view). Amazing for a first-time contribution! 😻 🚀 🎉

This is expected to ship in VS 2022 17.12 Preview 3.

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@StephanTLavavej StephanTLavavej StephanTLavavej approved these changes

@CaseyCarter CaseyCarter CaseyCarter approved these changes

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Optimize string_view::operator== when comparing 2 empty string_views
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@YexuanXiao @StephanTLavavej @CaseyCarter