Bug 65954 - DFG JIT heap prediction causes regressions when combined with aggressive integer prediction
Summary: DFG JIT heap prediction causes regressions when combined with aggressive inte...
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: 2011-08-09 19:05 PDT by Filip Pizlo
Modified: 2011-08-10 00:07 PDT (History)
3 users (show)

See Also:


Attachments
the patch (1.36 KB, patch)
2011-08-09 19:09 PDT, Filip Pizlo
no flags Details | Formatted Diff | Diff

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Description Filip Pizlo 2011-08-09 19:05:50 PDT
Both of these patches produced speed-ups by themselves:

https://bugs.webkit.org/show_bug.cgi?id=65883
https://bugs.webkit.org/show_bug.cgi?id=65949

But when combined, they produce slow-downs.  Because the latter one was a bigger speed-up, the former should probably be disabled until the reasons behind the regressions are better understood.
Comment 1 Filip Pizlo 2011-08-09 19:09:09 PDT
Created attachment 103430 [details]
the patch

This improves performance on v8-crypto by 20%, bringing us back to where we were before we regressed.  It does *not* remove the heap load prediction capability; it merely disables it, making it easier to reenable it if we figure out what is going wrong.
Comment 2 Gavin Barraclough 2011-08-09 22:28:43 PDT
Comment on attachment 103430 [details]
the patch

Seems like the smart move.  Should probably revert properly if we don't get these working well together, but this seems a sensible step for now.
Comment 3 Filip Pizlo 2011-08-09 23:09:32 PDT
Comment on attachment 103430 [details]
the patch

Tests pass, ready to land.
Comment 4 WebKit Review Bot 2011-08-10 00:07:12 PDT
Comment on attachment 103430 [details]
the patch

Clearing flags on attachment: 103430

Committed r92750: <http://trac.webkit.org/changeset/92750>
Comment 5 WebKit Review Bot 2011-08-10 00:07:17 PDT
All reviewed patches have been landed.  Closing bug.