RESOLVED WONTFIX306081
[appearance: base] Move the pseudoElementType and pseudoBits to NonInheritedRareData 
https://bugs.webkit.org/show_bug.cgi?id=306081
Summary [appearance: base] Move the pseudoElementType and pseudoBits to NonInheritedR...
Said Abou-Hallawa
Reported 2026-01-22 17:31:08 PST
Adding a pseudo element requires increasing PublicPseudoIDBits by 1. At some point an extra bit will add 4 bytes to the NonInheritedFlags. And because of the structure alignment, this will increase RenderStyle by 8 bytes. This caused perf regression on SP3 and on MotionMark; see bug 305085. To allow adding more pseudo elements without regressing the benchmarks. the pseudoElementType and pseudoBits can be moved from ComputedStyleBase::NonInheritedFlags to NonInheritedMiscData.
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Radar WebKit Bug Importer
Comment 1 2026-01-22 17:31:18 PST
<rdar://problem/168722225>
Said Abou-Hallawa
Comment 2 2026-01-22 17:40:57 PST
Pull request: https://github.com/WebKit/WebKit/pull/57093
Said Abou-Hallawa
Comment 3 2026-01-27 21:49:20 PST
The approach of this bug is wrong. Moving the pseudo elements bits to the rare data causes more mismatch in the MatchedDeclarationsCache. This should be fixed by bug 306383.
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