Bug 144456

Summary:

TypeOfIsUndefined by-type folding should take advantage of the masquerades-as-undefined watchpoint

Product:

WebKit

Reporter:

Filip Pizlo <fpizlo>

Component:

JavaScriptCore

Assignee:

Alexey Shvayka <ashvayka>

Status:

NEW

Severity:

Enhancement

CC:

ashvayka, ews-watchlist, keith_miller, mark.lam, msaboff, saam, tzagallo

Priority:

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+	Details Formatted Diff Diff
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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