Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: de9231d86e640102a22bc9a6091eb6dbf94bb4d4
https://github.com/WebKit/WebKit/commit/de9231d86e640102a22bc9a6091eb6dbf94bb4d4
Author: Sosuke Suzuki <[email protected]>
Date: 2026-08-19 (Wed, 19 Aug 2026)
Changed paths:
M Source/JavaScriptCore/runtime/RegExp.cpp
M Source/JavaScriptCore/runtime/RegExp.h
Log Message:
-----------
[JSC] Use `FixedVector` for `RegExp::m_ovector` and
`RareData::m_captureGroupNames`
https://bugs.webkit.org/show_bug.cgi?id=322090
Reviewed by Yusuke Suzuki.
Both vectors are sized once in RegExp::finishCreation and never grow, so
Vector's capacity field is wasted. Worse, Vector::resize honors the default
minCapacity of 16, so every RegExp allocated 64 bytes of ovector storage even
though most patterns need 2-8 ints.
Switching to FixedVector shrinks RegExp from 88 to 80 bytes (96 -> 80 byte GC
cell) and allocates exactly offsetVectorSize ints. Per RegExp this is 160 -> 96
bytes of cell + ovector storage as reported by generateHeapSnapshot(), and
maximum RSS with 200,000 live RegExps drops from 137.5 MB to 115.0 MB.
RareData::m_captureGroupNames gets the same treatment, shrinking RareData from
48 to 32 bytes for patterns with named groups.
estimatedSize now reports the exact ovector allocation via byteSize().
* Source/JavaScriptCore/runtime/RegExp.cpp:
(JSC::RegExp::finishCreation):
(JSC::RegExp::estimatedSize):
* Source/JavaScriptCore/runtime/RegExp.h:
Canonical link: https://commits.webkit.org/319495@main
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