[webkit-changes] [WebKit/WebKit] 4cd206: [JSC] Add fast path for `Iterator.prototype.toArray`

[SUZUKI Sosuke]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 4cd20629601f53916b5afc75bf2c3bac83980f66
      https://github.com/WebKit/WebKit/commit/4cd20629601f53916b5afc75bf2c3bac83980f66
  Author: Sosuke Suzuki <aosukeke at gmail.com>
  Date:   2024-09-14 (Sat, 14 Sep 2024)

  Changed paths:
    A JSTests/microbenchmarks/iterator-prototype-toArray-for-array.js
    A JSTests/stress/iterator-prototype-toArray-empty.js
    M Source/JavaScriptCore/runtime/ArrayPrototype.cpp
    M Source/JavaScriptCore/runtime/ArrayPrototypeInlines.h
    M Source/JavaScriptCore/runtime/JSArray.cpp
    M Source/JavaScriptCore/runtime/JSArray.h
    M Source/JavaScriptCore/runtime/JSArrayInlines.h
    M Source/JavaScriptCore/runtime/JSIteratorPrototype.cpp

  Log Message:
  -----------
  [JSC] Add fast path for `Iterator.prototype.toArray`
https://bugs.webkit.org/show_bug.cgi?id=279489

Reviewed by Yusuke Suzuki.

This patch adds a fast path for `Iterator.prototype.toArray.call(Array)`. It uses the same logic as
the already existing fast path for `Array.from(Array)`[1].

With this patch, performance on microbenchmarks improves by approximately 2.3x.

                                              TipOfTree                  Patched

iterator-prototype-toArray-for-array        0.7119+-0.0159     ^      0.3019+-0.0052        ^ definitely 2.3578x faster

Even though this patch shares some code with `Array.from`, there are no performance regressions.

                                TipOfTree                  Patched

array-from-array              0.3007+-0.0145            0.2976+-0.0057          might be 1.0103x faster
array-from-arraylike         29.8513+-0.4606     ^     29.1788+-0.1179        ^ definitely 1.0230x faster

[1]: https://commits.webkit.org/269690@main

* JSTests/microbenchmarks/iterator-prototype-toArray-for-array.js: Added.
* JSTests/stress/iterator-prototype-toArray-empty.js: Added.
(shouldBe):
(throw.new.Error):
(else.shouldBe):
* Source/JavaScriptCore/runtime/ArrayPrototype.cpp:
(JSC::concatAppendOne):
(JSC::JSC_DEFINE_HOST_FUNCTION):
(JSC::moveElements): Deleted.
(JSC::clearElement): Deleted.
(JSC::copyElements): Deleted.
* Source/JavaScriptCore/runtime/ArrayPrototypeInlines.h:
(JSC::getProperty): Deleted.
* Source/JavaScriptCore/runtime/JSArray.cpp:
(JSC::clearElement):
* Source/JavaScriptCore/runtime/JSArray.h:
(JSC::moveArrayElements):
(JSC::clearElement):
(JSC::copyArrayElements):
* Source/JavaScriptCore/runtime/JSArrayInlines.h:
(JSC::getProperty):
* Source/JavaScriptCore/runtime/JSIteratorPrototype.cpp:
(JSC::JSC_DEFINE_HOST_FUNCTION):

Canonical link: https://commits.webkit.org/283672@main



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