Bug 65234 - DFG graph has no notion of double prediction
Summary: DFG graph has no notion of double prediction
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: JavaScriptCore (show other bugs)
Version: 528+ (Nightly build)
Hardware: All All
: P2 Normal
Assignee: Nobody
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2011-07-26 23:24 PDT by Filip Pizlo
Modified: 2011-07-27 20:25 PDT (History)
3 users (show)

See Also:


Attachments
the patch (10.69 KB, patch)
2011-07-26 23:46 PDT, Filip Pizlo
no flags Details | Formatted Diff | Diff

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Description Filip Pizlo 2011-07-26 23:24:34 PDT
The DFG graph has notions of Int32, cell, and array predictions, but no notion of double prediction.  Furthermore, it has no notion of the least-upper-bound of predictions, or of distinguishing between a top prediction (where we know that the node can have every type because we've got confirmed sightings of assignments of all of the different types) and a bottom prediction (we have no information pointing in the direction of any particular type).
Comment 1 Filip Pizlo 2011-07-26 23:46:35 PDT
Created attachment 102097 [details]
the patch

This is performance-neutral, but shows sights of slight speed-ups in Kraken.  It's meant as a stepping stone for other optimizations which would otherwise cause slow-downs due to overzealous int speculation.
Comment 2 WebKit Review Bot 2011-07-27 20:25:32 PDT
Comment on attachment 102097 [details]
the patch

Clearing flags on attachment: 102097

Committed r91894: <http://trac.webkit.org/changeset/91894>
Comment 3 WebKit Review Bot 2011-07-27 20:25:36 PDT
All reviewed patches have been landed.  Closing bug.