Bug 65404

Summary: JSC GC zombie support no longer works, and is likely no longer needed
Product: WebKit Reporter: Filip Pizlo <fpizlo>
Component: JavaScriptCoreAssignee: Nobody <webkit-unassigned>
Status: RESOLVED FIXED    
Severity: Normal CC: fpizlo, oliver, webkit.review.bot, zherczeg
Priority: P2    
Version: 528+ (Nightly build)   
Hardware: All   
OS: All   
Attachments:
Description Flags
the patch
darin: review+, webkit-ews: commit-queue-
the patch (fix various platforms) none

Description Filip Pizlo 2011-07-29 18:00:34 PDT 
The JSC GC has support for installing zombie cells in free memory as a way of tracking when a reference in the heap is missed.  But this functionality no longer works, and is not tested during any regressions (either in bots or in command-line tools).  It's not clear that it's needed, since WebCore and JSC appear to track references accurately enough to be correct.  Furthermore, it's not clear that the GC should continue to support a relatively complex piece of untested functionality, which makes implementing new features difficult, and whose existence is predicated upon the GC being broken.  In short, zombie support should be removed unless a good argument can be made for its necessity.
Comment 1 Filip Pizlo 2011-07-29 18:14:11 PDT 
Created attachment 102416 [details]
the patch
Comment 2 Early Warning System Bot 2011-07-29 18:24:16 PDT 
Comment on attachment 102416 [details]
the patch

Attachment 102416 [details] did not pass qt-ews (qt):
Output: http://queues.webkit.org/results/9267624
Comment 3 Gyuyoung Kim 2011-07-29 18:29:11 PDT 
Comment on attachment 102416 [details]
the patch

Attachment 102416 [details] did not pass efl-ews (efl):
Output: http://queues.webkit.org/results/9267623
Comment 4 Filip Pizlo 2011-07-29 18:40:44 PDT 
Created attachment 102419 [details]
the patch (fix various platforms)
Comment 5 WebKit Review Bot 2011-07-29 19:50:00 PDT 
Comment on attachment 102419 [details]
the patch (fix various platforms)

Clearing flags on attachment: 102419

Committed r92046: <http://trac.webkit.org/changeset/92046>
Comment 6 WebKit Review Bot 2011-07-29 19:50:05 PDT 
All reviewed patches have been landed.  Closing bug.
Comment 7 Zoltan Herczeg 2011-07-29 22:25:34 PDT 
Sad thing... was a nice feature.