Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 3130bd507b02a77372bf2365ddf0164e546c6605
https://github.com/WebKit/WebKit/commit/3130bd507b02a77372bf2365ddf0164e546c6605
Author: Sosuke Suzuki <[email protected]>
Date: 2026-07-15 (Wed, 15 Jul 2026)
Changed paths:
A JSTests/microbenchmarks/string-replace-regexp-global-single-match.js
A
JSTests/microbenchmarks/string-replace-regexp-global-thousands-separator.js
M Source/JavaScriptCore/runtime/JSString.h
M Source/JavaScriptCore/runtime/OperationsInlines.h
M Source/JavaScriptCore/runtime/StringPrototype.cpp
M Source/JavaScriptCore/runtime/StringPrototypeInlines.h
Log Message:
-----------
[JSC] Use the generic path in `jsSpliceSubstringsWithSeparator(s)` for short
two-range results
https://bugs.webkit.org/show_bug.cgi?id=319023
Reviewed by Yusuke Suzuki.
For a global RegExp replace with a single match (rangeCount == 2,
separatorCount == 1),
we create two substring StringImpls and concatenate them with jsString(). But
when the
result is short, jsString() flattens it via tryMakeString() anyway, so this
costs three
allocations and a double copy — strictly slower than the generic
single-allocation path
below. This hits the common thousands-separator idiom
`String(n).replace(/\B(?=(\d{3})+(?!\d))/g, ",")` for 4-6 digit numbers.
Take the special case only when jsString() would actually make a rope. The
threshold is
extracted into shouldMakeRope() in JSString.h and shared with the jsString()
overloads.
Baseline
Patched
string-replace-generic 19.7240+-0.6320 ^
14.7327+-0.3753 ^ definitely 1.3388x faster
string-replace-regexp-global-thousands-separator
153.5817+-1.6965 ^
120.7386+-1.0667 ^ definitely 1.2720x faster
string-replace-regexp-global-single-match
152.1385+-0.4575 ^
102.3380+-0.7269 ^ definitely 1.4866x faster
Tests: JSTests/microbenchmarks/string-replace-regexp-global-single-match.js
JSTests/microbenchmarks/string-replace-regexp-global-thousands-separator.js
* JSTests/microbenchmarks/string-replace-regexp-global-single-match.js: Added.
(test):
* JSTests/microbenchmarks/string-replace-regexp-global-thousands-separator.js:
Added.
(test):
* Source/JavaScriptCore/runtime/JSString.h:
(JSC::shouldMakeRope):
* Source/JavaScriptCore/runtime/OperationsInlines.h:
(JSC::jsString):
* Source/JavaScriptCore/runtime/StringPrototypeInlines.h:
(JSC::jsSpliceSubstringsWithSeparators):
(JSC::jsSpliceSubstringsWithSeparator):
Canonical link: https://commits.webkit.org/317282@main
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