Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 047e076765717fc250af0d6b5f5abdd63af0a0cd
https://github.com/WebKit/WebKit/commit/047e076765717fc250af0d6b5f5abdd63af0a0cd
Author: Ahmad Saleem <[email protected]>
Date: 2026-10-09 (Fri, 09 Oct 2026)
Changed paths:
A PerformanceTests/CSS/CSSRemoveShorthandProperty.html
M Source/WebCore/css/MutableStyleProperties.cpp
Log Message:
-----------
MutableStyleProperties::removeProperties() allocates a HashSet on every call
https://bugs.webkit.org/show_bug.cgi?id=326907
rdar://189568792
Reviewed by Antti Koivisto.
removeProperties() built a temporary HashSet<CSSPropertyID> from its input
span on every call, only to discard it after a single removeAllMatching()
pass. It is called whenever a shorthand is removed or set via CSSOM, and
repeatedly from editing code (EditingStyle, ReplaceSelectionCommand), often
once per node.
Replace it with a stack-allocated WTF::BitSet<cssPropertyIDEnumValueCount>,
matching CSSProperty::colorProperties / physicalProperties. This avoids the
heap allocation and hashing, and keeps membership checks O(1) even for large
inputs like the `all` shorthand, where a linear std::ranges::contains scan
would be quadratic.
This improves PerformanceTests/CSS/CSSRemoveShorthandProperty.html from
203 to 508 runs/s (~2.5x) on an M3 Max machine.
* PerformanceTests/CSS/CSSRemoveShorthandProperty.html: Added.
* Source/WebCore/css/MutableStyleProperties.cpp:
(WebCore::MutableStyleProperties::removeProperties):
Canonical link: https://commits.webkit.org/323206@main
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