508061 - INITELEM behavior differs with -j

Status: RESOLVED WORKSFORME

(Core :: JavaScript Engine, defect)

Description

[Jason Orendorff [:jorendorff]]

function loop() {
    var x;
    for (var i = 0; i < 9; i++)
        x = {1.5: 1};
    return x;
}

loop(); // record
Object.prototype.__defineSetter__('1.5', function () { return 'BAD'; });
var x = loop(); // playback
assertEq(x["1.5"], 1);

//without -j:   test passes.
//with -j:      TypeError: Assertion failed: got (void 0), expected 1

Comment 1

[Jason Orendorff [:jorendorff]]

I found this after reading the following code:

  JS_REQUIRES_STACK JSRecordingStatus
  TraceRecorder::record_JSOP_INITELEM()
  {
      return record_JSOP_SETELEM();
  }

which seemed so implausible that I felt compelled to write a few test cases.
However, none of my tests broke in quite the way I expected, so I really
have no idea what causes this bug!

Comment 2

[Tom S [:evilpie]]

I think that has been fixed.

Comment 3

[Tom S [:evilpie]]

https://hg.mozilla.org/integration/mozilla-inbound/rev/de56ae61946d

Comment 4

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/de56ae61946d