Bug 252904 - Performance regression on selector match benchmark (add UNLIKELY to help branch prediction)
Summary: Performance regression on selector match benchmark (add UNLIKELY to help bran...
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: WebCore Misc. (show other bugs)
Version: WebKit Nightly Build
Hardware: Unspecified Unspecified
: P2 Normal
Assignee: Nobody
URL:
Keywords: InRadar
Depends on:
Blocks:
 
Reported: 2023-02-24 07:36 PST by Matthieu Dubet
Modified: 2023-03-17 14:59 PDT (History)
1 user (show)

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Description Matthieu Dubet 2023-02-24 07:36:40 PST 
The introduction of css-nesting (original VS resolved selector list) has introduced a small performance regression on selector matching benchmark.

https://perf.webkit.org/v3/#/charts?since=1663309346443&paneList=((22-1649-null-null-(5-2.5-500)))

Adding a UNLIKELY to help the compiler mitigate the performance decrease in the most frequent case (no nesting) could help.
Comment 1 Radar WebKit Bug Importer 2023-02-24 07:37:10 PST 
<rdar://problem/105883716>
Comment 2 Matthieu Dubet 2023-02-24 14:03:16 PST 
Pull request: https://github.com/WebKit/WebKit/pull/10665
Comment 3 Matthieu Dubet 2023-03-17 08:43:07 PDT 
Pull request: https://github.com/WebKit/WebKit/pull/11656
Comment 4 EWS 2023-03-17 14:59:52 PDT 
Committed 261809@main (29a558295527): <https://commits.webkit.org/261809@main>

Reviewed commits have been landed. Closing PR #11656 and removing active labels.