Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 7aeed1e3bd69527b49cf85957c5d53d0044fbd7a
https://github.com/WebKit/WebKit/commit/7aeed1e3bd69527b49cf85957c5d53d0044fbd7a
Author: Sosuke Suzuki <[email protected]>
Date: 2026-09-13 (Sun, 13 Sep 2026)
Changed paths:
A JSTests/microbenchmarks/string-replace-regexp-strip-prefix.js
A JSTests/stress/string-replace-regexp-non-global-string-replacement.js
M Source/JavaScriptCore/runtime/StringPrototypeInlines.h
Log Message:
-----------
[JSC] Non-global `RegExp#replace` with an empty string should return a
substring
https://bugs.webkit.org/show_bug.cgi?id=323409
Reviewed by Yusuke Suzuki.
`url.replace(/^https?:\/\//, "")` and similar idioms that strip a prefix or
a suffix copied the rest of the subject into a new StringImpl, so the cost
grew with the length of the string. The string-search version of replace
already returns substring cells for this.
When the replacement is empty and the match touches either end of the
subject, return a substring of the subject. Other cases keep the flat copy,
because a rope of several pieces is slower once it is resolved.
Baseline Patched
string-replace-regexp-trim-end 16.5122+-0.2286 ?
16.5982+-0.2722 ?
string-replace-regexp-trim-start 15.8060+-0.2518
15.5517+-0.1634 might be 1.0163x faster
string-replace-regexp-strip-prefix 56.5716+-0.4533 ^
24.6314+-0.1697 ^ definitely 2.2967x faster
string-replace-empty 6.6183+-0.2257 ^
6.2340+-0.1388 ^ definitely 1.0616x faster
Tests: JSTests/microbenchmarks/string-replace-regexp-strip-prefix.js
JSTests/stress/string-replace-regexp-non-global-string-replacement.js
* JSTests/microbenchmarks/string-replace-regexp-strip-prefix.js: Added.
(test):
* JSTests/stress/string-replace-regexp-non-global-string-replacement.js: Added.
(shouldBe):
(replaceEmpty):
(replaceString):
* Source/JavaScriptCore/runtime/StringPrototypeInlines.h:
(JSC::replaceOneWithStringUsingRegExpSearch):
Canonical link: https://commits.webkit.org/321015@main
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