Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 96ca975b2a61a52093cccecd9249e2b410085eea
https://github.com/WebKit/WebKit/commit/96ca975b2a61a52093cccecd9249e2b410085eea
Author: Sosuke Suzuki <[email protected]>
Date: 2026-08-22 (Sat, 22 Aug 2026)
Changed paths:
A JSTests/microbenchmarks/object-assign-clone-multiple-sources.js
A JSTests/stress/object-assign-clone-multiple-sources.js
M Source/JavaScriptCore/runtime/ObjectConstructor.cpp
Log Message:
-----------
[JSC] Use `objectCloneFast` for the first source in `Object.assign`'s
batching path
https://bugs.webkit.org/show_bug.cgi?id=322161
Reviewed by Yusuke Suzuki.
Object.assign({}, state, patch) with 2 or 3 sources goes through the batching
path in
objectConstructorAssign, which enumerates every source and replays the first
source's
shape one property at a time via putOwnDataPropertyBatching. objectCloneFast is
only
reachable from objectAssignFast, which is used for a single source or 5+
arguments.
Try objectCloneFast for the first source at the start of the batching path and
start
the per-source loop from the second source when it succeeds. The batching path's
existing preconditions already satisfy what objectCloneFast requires.
Baseline Patched
object-assign-clone-multiple-sources 0.9998+-0.0420 ^
0.7104+-0.0486 ^ definitely 1.4073x faster
object-assign-multiple-sources 9.5170+-0.2249 ^
6.2294+-0.2320 ^ definitely 1.5278x faster
Tests: JSTests/microbenchmarks/object-assign-clone-multiple-sources.js
JSTests/stress/object-assign-clone-multiple-sources.js
* JSTests/microbenchmarks/object-assign-clone-multiple-sources.js: Added.
* JSTests/stress/object-assign-clone-multiple-sources.js: Added.
(shouldBe):
(shouldBeArray):
(makeState):
* Source/JavaScriptCore/runtime/ObjectConstructor.cpp:
(JSC::JSC_DEFINE_HOST_FUNCTION):
Canonical link: https://commits.webkit.org/319645@main
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