Bug 144456

Summary: TypeOfIsUndefined by-type folding should take advantage of the masquerades-as-undefined watchpoint
Product: WebKit Reporter: Filip Pizlo <fpizlo>
Component: JavaScriptCoreAssignee: Alexey Shvayka <ashvayka>
Status: NEW    
Severity: Enhancement CC: ashvayka, ews-watchlist, keith_miller, mark.lam, msaboff, saam, tzagallo
Priority: P2    
Version: WebKit Nightly Build   
Hardware: All   
OS: All   
Bug Depends on: 144409    
Bug Blocks:    
Attachments:
Description Flags
Patch fpizlo: review+

Filip Pizlo
Reported 2015-04-30 10:31:02 PDT
This would allow us to fold more things.
Attachments
Patch (5.23 KB, patch)
2021-08-04 14:52 PDT, Alexey Shvayka 		fpizlo: review+
DetailsFormatted DiffDiff
View All Add attachment proposed patch, testcase, etc.
Alexey Shvayka
Comment 1 2021-08-04 14:52:44 PDT
Created attachment 434939 [details] Patch
Alexey Shvayka
Comment 2 2021-08-04 14:53:30 PDT
(In reply to Alexey Shvayka from comment #1) > Created attachment 434939 [details] > Patch r280626 patch is-undefined-fold-tricky-spec-object-other 30.6171+-0.7028 ^ 21.8494+-0.6913 ^ definitely 1.4013x faster
Filip Pizlo
Comment 3 2021-08-04 15:10:39 PDT
Comment on attachment 434939 [details] Patch View in context: https://bugs.webkit.org/attachment.cgi?id=434939&action=review > Source/JavaScriptCore/ChangeLog:12 > + TypeOfIsObject / TypeOfIsFunction by-type folding can't be improved in the same way: > + even if SpecObjectOther is a proven non-masquerader, we don't know if it's callable. Can you replace the FIXME's with comments to this effect? This is an easy detail to forget. I would say something like - we could use the masquerade watchpoint to prove it's not undefined, but we don't have a trick for callability.
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