[webkit-changes] [WebKit/WebKit] 9b945b: [JSC] Bracket update expression should resolve pro...

[Ross Kirsling]

  Branch: refs/heads/main
  Home:   https://github.com/WebKit/WebKit
  Commit: 9b945bdd8d46d2755cb115acb4596b3ed14d97eb
      https://github.com/WebKit/WebKit/commit/9b945bdd8d46d2755cb115acb4596b3ed14d97eb
  Author: Ross Kirsling <ross.kirsling at sony.com>
  Date:   2024-02-29 (Thu, 29 Feb 2024)

  Changed paths:
    M JSTests/test262/expectations.yaml
    M Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp

  Log Message:
  -----------
  [JSC] Bracket update expression should resolve property key at most once
https://bugs.webkit.org/show_bug.cgi?id=270150

Reviewed by Justin Michaud.

Currently, in an expression like `obj[prop]++`, we double-evaluate `prop`, as GetByVal and PutByVal
each perform ToPropertyKey separately. To correct this, we need to perform ToPropertyKey in advance,
but only after ensuring that `obj` is object-coercible; if it isn't, we shouldn't perform ToPropertyKey at all.

This extra work can be bypassed for literal numbers and strings;
as a drive-by fix, this patch corrects a case which was intending to perform a similar bypass,
but which mixed up || and &&, thereby ending up with a constant true.

* JSTests/test262/expectations.yaml: Mark 8 test cases as passing.
* Source/JavaScriptCore/bytecompiler/NodesCodegen.cpp:
(JSC::PostfixNode::emitBracket):
(JSC::PrefixNode::emitBracket):
(JSC::ObjectPatternNode::bindValue const):

Canonical link: https://commits.webkit.org/275531@main



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