[webkit-reviews] review requested: [Bug 80365] PredictNone is incorrectly treated as isDoublePrediction : [Attachment 130269] the patch

[bugzilla-daemon at webkit.org]

Yuqiang Xian <yuqiang.xian at intel.com> has asked  for review:
Bug 80365: PredictNone is incorrectly treated as isDoublePrediction
https://bugs.webkit.org/show_bug.cgi?id=80365

Attachment 130269: the patch
https://bugs.webkit.org/attachment.cgi?id=130269&action=review

------- Additional Comments from Yuqiang Xian <yuqiang.xian at intel.com>
Attention: One performance regression on SunSpider-bitops-nsieve-bits. The root
cause is identified - In ToT, a dead/unused variable was marked as ForcedDouble
simply because it has PredictNone (as we don't propagate the type information
for the dead/unused variables), and is treated as a Double prediction - so OSR
performed successfully (that unused variable actually happened to be an
integer, see line 108 in DFGOSREntry.cpp). But with this bug fix, the OSR is
failed because there's no type prediction for the unused variable. Separated
bug will be filed against this.