Branch: refs/heads/main
Home: https://github.com/WebKit/WebKit
Commit: b6a9b84dae1faa215e4deb5a9f5932aee10d12e5
https://github.com/WebKit/WebKit/commit/b6a9b84dae1faa215e4deb5a9f5932aee10d12e5
Author: Sosuke Suzuki <[email protected]>
Date: 2026-06-09 (Tue, 09 Jun 2026)
Changed paths:
A JSTests/microbenchmarks/class-fields-anonymous-arrow-function-fields.js
A JSTests/stress/class-fields-anonymous-function-name-edge-cases.js
A JSTests/stress/class-fields-anonymous-function-name-inference.js
M Source/JavaScriptCore/parser/ASTBuilder.h
M Source/JavaScriptCore/parser/Parser.cpp
Log Message:
-----------
[JSC] Set class field function names at parse time instead of via
`SetFunctionName`
https://bugs.webkit.org/show_bug.cgi?id=316646
Reviewed by Yusuke Suzuki.
Anonymous functions and classes in class field initializers get their names
via op_set_function_name, which eagerly reifies the "name" property on every
closure created each time an instance is constructed (FunctionRareData +
JSString + butterfly per function-valued field). Object literal properties and
assignments already avoid this by inferring the name at parse time, but class
fields miss that inference because their initializers are re-parsed separately
via parseClassFieldInitializerSourceElements.
Apply the same ecmaName inference in ASTBuilder::createDefineField for
non-computed field names, so no op_set_function_name is emitted and "name" is
reified lazily like any named function. Also iterate class element definitions
by reference, since ClassExprNode::setEcmaName captures a pointer to the
identifier. The inferred name now also becomes visible to static member
initializers per spec.
baseline parseronly
class-fields-anonymous-arrow-function-fields
43.1214+-0.3197 ^ 4.6281+-0.1775
^ definitely 9.3172x faster
Tests: JSTests/microbenchmarks/class-fields-anonymous-arrow-function-fields.js
JSTests/stress/class-fields-anonymous-function-name-edge-cases.js
JSTests/stress/class-fields-anonymous-function-name-inference.js
* JSTests/microbenchmarks/class-fields-anonymous-arrow-function-fields.js:
Added.
(bench):
* JSTests/stress/class-fields-anonymous-function-name-edge-cases.js: Added.
(shouldBe):
(shouldBe.O):
(prototype.shouldBe.O.prototype.string_appeared_here):
(prototype.shouldBe.O):
(prototype.shouldBe):
(prototype.shouldBe.O.prototype.p):
(prototype.shouldBe.O.prototype.t.true):
(prototype.shouldBe.O.prototype.a):
(prototype.shouldBe.O.async g):
(prototype.shouldBe.O.ag):
(prototype.shouldBe.O.async af):
(O.inner):
(O):
(prototype.shouldBe.make.D):
(prototype.throw.new.Error.makeClass.return.f):
(prototype.throw.new.Error.makeClass):
(prototype.throw.new.Error):
(prototype.shouldBe.Base):
* JSTests/stress/class-fields-anonymous-function-name-inference.js: Added.
(shouldBe):
(C.g):
(C.n):
(C.prototype.getP):
(prototype.shouldBe):
(prototype.shouldBe.S):
(prototype.shouldBe.make.D):
(prototype.shouldBe.make):
(prototype.shouldBe.E.m):
(prototype.shouldBe.E):
(prototype.shouldBe.F):
* Source/JavaScriptCore/parser/ASTBuilder.h:
(JSC::ASTBuilder::createDefineField):
* Source/JavaScriptCore/parser/Parser.cpp:
(JSC::Parser<LexerType>::parseClassFieldInitializerSourceElements):
Canonical link: https://commits.webkit.org/314873@main
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