Bug 64659 - DFG JIT does not optimize equal-null comparisons and branches
: DFG JIT does not optimize equal-null comparisons and branches
Status: RESOLVED FIXED
: WebKit
JavaScriptCore
: 528+ (Nightly build)
: All All
: P2 Normal
Assigned To:
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Reported: 2011-07-16 16:20 PST by
Modified: 2011-07-18 14:05 PST (History)


Attachments
the patch (10.07 KB, patch)
2011-07-18 10:29 PST, Filip Pizlo
no flags Review Patch | Details | Formatted Diff | Diff


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Description From 2011-07-16 16:20:13 PST
The DFG JIT bytecode parser converts equal-null compare/branch opcodes into a tree of JSConstant(null), an equality comparison, and a branch.  The backend never special-cases the equal-to-null case, and treats it as a normal equality comparison; this means that equal-null always takes slow path.  The DFG JIT backend should have a peephole optimization for this case.
------- Comment #1 From 2011-07-18 10:29:42 PST -------
Created an attachment (id=101170) [details]
the patch
------- Comment #2 From 2011-07-18 14:05:03 PST -------
(From update of attachment 101170 [details])
Clearing flags on attachment: 101170

Committed r91208: <http://trac.webkit.org/changeset/91208>
------- Comment #3 From 2011-07-18 14:05:07 PST -------
All reviewed patches have been landed.  Closing bug.