RESOLVED FIXED Bug 68735
DFG implementation of PutScopedVar corrupts register allocation 
https://bugs.webkit.org/show_bug.cgi?id=68735
Summary DFG implementation of PutScopedVar corrupts register allocation
Filip Pizlo
Reported 2011-09-23 14:54:08 PDT
The PutScopedVar case in DFGSpeculativeJIT.cpp does not call noResult(), causing its child (the scope chain) to remain referenced. It then does not get removed from the register bank, and its virtual register does not get cleared. This has two effects: bizarre assertion failures and possibly regressed performance in the absence of assertion failures, due to increased register pressure.
Attachments
the patch (1.27 KB, patch)
2011-09-23 14:55 PDT, Filip Pizlo 		oliver: review+
oliver: commit-queue+
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Filip Pizlo
Comment 1 2011-09-23 14:55:43 PDT
Created attachment 108543 [details] the patch
Oliver Hunt
Comment 2 2011-09-23 14:56:50 PDT
Comment on attachment 108543 [details] the patch oooh, i didn't realise that was necessary/existed -- best to check my other changes for similar screw ups :-(
Filip Pizlo
Comment 3 2011-09-23 14:57:56 PDT
(In reply to comment #2) > (From update of attachment 108543 [details]) > oooh, i didn't realise that was necessary/existed -- best to check my other changes for similar screw ups :-( GetScopeChain and GetScopeVar are right, because they call the relevant xyzResult methods. It's the ones that don't return anything that are annoying.
Oliver Hunt
Comment 4 2011-09-23 15:12:20 PDT
Committed r95868: <http://trac.webkit.org/changeset/95868>
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