Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: 4b8e37abf2836c3dda3db728c5e2e82de59c7a49
https://github.com/WebKit/WebKit/commit/4b8e37abf2836c3dda3db728c5e2e82de59c7a49
Author: Tetsuharu Ohzeki <[email protected]>
Date: 2026-07-22 (Wed, 22 Jul 2026)
Changed paths:
M Source/JavaScriptCore/runtime/JSArray.cpp
Log Message:
-----------
[JSC] Use pass-by-value for `resultIndex` argument of
`JS::fastFlatIntoBuffer()`
https://bugs.webkit.org/show_bug.cgi?id=319673
Reviewed by Sosuke Suzuki.
This change is related to only the fast path of `Array#flat()`.
`resultIndex` is 8-bytes (`uint64_t`). It's enough small size.
Interestingly, this change has a side-effect which is a micro benchmark
progression on macOS arm64 at least.
TipOfTree Patched
array-prototype-flat-depth-1-string 124.7313+-15.7674 ?
126.7053+-14.0930 ? might be 1.0158x slower
array-prototype-flat-depth-1-double 85.8047+-8.6982 ?
88.9680+-4.1780 ? might be 1.0369x slower
array-prototype-flat-large-nested 45.0930+-2.4765 ^
27.1562+-1.0824 ^ definitely 1.6605x faster
array-prototype-flat-huge-arrays 10.5353+-1.8040
10.0453+-1.7224 might be 1.0488x faster
array-prototype-flat-small-arrays 3.4522+-0.1238
3.3026+-0.0755 might be 1.0453x faster
array-prototype-flat-depth-infinity 117.2919+-1.0095
117.0930+-0.6006
array-prototype-flat-depth-2 94.7117+-1.3260 ?
95.6852+-4.3372 ? might be 1.0103x slower
array-prototype-flat-depth-1-int32 85.2135+-4.3134 ?
88.4635+-2.5566 ? might be 1.0381x slower
array-prototype-flat-depth-3 105.7020+-7.5027
102.3541+-4.5175 might be 1.0327x faster
array-prototype-flat-sparse-array 152.1396+-3.2477 ?
161.3152+-11.0580 ? might be 1.0603x slower
array-prototype-flat-depth-1-mixed 93.9877+-4.2939 ?
94.3616+-4.7335 ?
<geometric> 57.9736+-0.6088 ^
55.5547+-0.9141 ^ definitely 1.0435x faster
No new tests.
It wlll be covered by exist test cases.
Canonical link: https://commits.webkit.org/317700@main
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