Bug 87682 - DFG should not generate code for code that the CFA proves to be unreachable
Summary: DFG should not generate code for code that the CFA proves to be unreachable
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: 2012-05-28 16:56 PDT by Filip Pizlo
Modified: 2012-05-28 19:43 PDT (History)
0 users

See Also:


Attachments
the patch (4.39 KB, patch)
2012-05-28 17:01 PDT, Filip Pizlo
no flags Details | Formatted Diff | Diff
the patch (6.92 KB, patch)
2012-05-28 19:09 PDT, Filip Pizlo
sam: review+
Details | Formatted Diff | Diff

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Description Filip Pizlo 2012-05-28 16:56:38 PDT
When the CFA proves code to be unreachable, we are stuck in a bit of a conundrum.  The code must still be known to other parts of the compiler because of OSR exit liveness issues, so it cannot be simply jettisoned.  But we shouldn't be spending time generating that code, and we shouldn't be allowing OSR entry into that code.
Comment 1 Filip Pizlo 2012-05-28 17:01:02 PDT
Created attachment 144410 [details]
the patch
Comment 2 Filip Pizlo 2012-05-28 19:09:56 PDT
Created attachment 144425 [details]
the patch

Cleaned up constant folding a bit more.
Comment 3 Filip Pizlo 2012-05-28 19:43:56 PDT
Landed in http://trac.webkit.org/changeset/118715