Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: fe4ff6d9c93646a9bdb7124a939ad0fe26451e98
https://github.com/WebKit/WebKit/commit/fe4ff6d9c93646a9bdb7124a939ad0fe26451e98
Author: Sosuke Suzuki <[email protected]>
Date: 2026-06-22 (Mon, 22 Jun 2026)
Changed paths:
A JSTests/microbenchmarks/string-replace-string-substitution.js
M Source/JavaScriptCore/runtime/IntlObject.cpp
M Source/JavaScriptCore/runtime/IntlPluralRules.cpp
M Source/JavaScriptCore/runtime/StringPrototypeInlines.h
Log Message:
-----------
[JSC] Avoid intermediate `StringImpl` allocation when feeding `StringBuilder`
into `makeString`
https://bugs.webkit.org/show_bug.cgi?id=317556
Reviewed by Yusuke Suzuki.
When a StringBuilder is passed to tryMakeString/makeString via toString(),
toString() shrinks the buffer and reifies a fresh StringImpl, which the
caller immediately copies from and discards. Passing StringView { builder }
lets the caller read directly from the builder's internal buffer.
Apply this in three places:
- tryMakeReplacedString (String.prototype.replace with a string search and
a `$` substitution in the replacement). This matches what the RegExp path
already does in replaceOneWithStringUsingRegExpSearch.
- resolveLocale, when stitching the supported -u- extension back into the
found locale.
- IntlPluralRules::initializePluralRules, where the skeleton builder was
reified only to be viewed as a StringView.
The Intl changes are allocation-only cleanups; ICU formatter construction
dominates those paths and the difference is below microbenchmark noise.
Baseline Fix
string-replace-string-substitution 67.4923+-0.7067 ^ 57.4668+-0.5274 ^
definitely 1.1745x faster
Test: JSTests/microbenchmarks/string-replace-string-substitution.js
* JSTests/microbenchmarks/string-replace-string-substitution.js: Added.
(test):
* Source/JavaScriptCore/runtime/IntlObject.cpp:
(JSC::resolveLocale):
* Source/JavaScriptCore/runtime/IntlPluralRules.cpp:
(JSC::IntlPluralRules::initializePluralRules):
* Source/JavaScriptCore/runtime/StringPrototypeInlines.h:
(JSC::tryMakeReplacedString):
Canonical link: https://commits.webkit.org/315643@main
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