Bug 65160 - DFG non-speculative JIT emits inefficient code for arithmetic involving two registers
Summary: DFG non-speculative JIT emits inefficient code for arithmetic involving two r...
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: 2011-07-25 20:06 PDT by Filip Pizlo
Modified: 2011-07-25 22:35 PDT (History)
1 user (show)

See Also:


Attachments
the patch (6.39 KB, patch)
2011-07-25 20:11 PDT, Filip Pizlo
no flags Details | Formatted Diff | Diff

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Description Filip Pizlo 2011-07-25 20:06:36 PDT
The DFG non-speculative JIT emits code for arithmetic that uses C helper functions in case the operands are not integers.  This results in bad performance regressions in case of speculation failure, where the hot code involves arithmetic on doubles.  The DFG non-speculative JIT should inline double arithmetic whenever possible, much like the old JSC JIT did.
Comment 1 Filip Pizlo 2011-07-25 20:11:50 PDT
Created attachment 101964 [details]
the patch

Tests are still running; will change flags to ? when/if they pass.
Comment 2 Filip Pizlo 2011-07-25 20:15:43 PDT
Comment on attachment 101964 [details]
the patch

Tests passed, ready for review.
Comment 3 Gavin Barraclough 2011-07-25 22:25:19 PDT
Comment on attachment 101964 [details]
the patch

View in context: https://bugs.webkit.org/attachment.cgi?id=101964&action=review

> Source/JavaScriptCore/ChangeLog:11
> +        (albeit a small one), and a large speed-up on Kraken.

We should start listing the magnitude of performance progressions in the ChangeLog.
Failure to do so is making Sam sad. ;-)
Comment 4 WebKit Review Bot 2011-07-25 22:35:13 PDT
Comment on attachment 101964 [details]
the patch

Clearing flags on attachment: 101964

Committed r91743: <http://trac.webkit.org/changeset/91743>
Comment 5 WebKit Review Bot 2011-07-25 22:35:17 PDT
All reviewed patches have been landed.  Closing bug.