[webkit-changes] [WebKit/WebKit] 4274ce: [JSC] MakeAtomString might have only one child

[Commit Queue]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 4274ce75b4aa14017a79bf4480b4da00189c63da
      https://github.com/WebKit/WebKit/commit/4274ce75b4aa14017a79bf4480b4da00189c63da
  Author: Yijia Huang <yijia_huang at apple.com>
  Date:   2023-06-12 (Mon, 12 Jun 2023)

  Changed paths:
    A JSTests/stress/make-atom-string-one-child.js
    M Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp

  Log Message:
  -----------
  [JSC] MakeAtomString might have only one child
https://bugs.webkit.org/show_bug.cgi?id=257983
rdar://110637049

Reviewed by Yusuke Suzuki.

DFG constant folding phase can optimize out one child of MakeAtomString node
if it has two children and one of them is an empty string. In this case,
the MakeAtomString node can have only one child after then.

* Source/JavaScriptCore/dfg/DFGStrengthReductionPhase.cpp:
(JSC::DFG::StrengthReductionPhase::handleNode):

Canonical link: https://commits.webkit.org/265101@main