[Webkit-unassigned] [Bug 72857] Optimize JITArithmetic32_64.cpp:: op_add & op_sub

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=72857


Filip Pizlo <fpizlo at apple.com> changed:

           What    |Removed                     |Added
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 Attachment #116030|review?, commit-queue?      |review-, commit-queue-
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--- Comment #3 from Filip Pizlo <fpizlo at apple.com>  2011-11-21 11:01:34 PST ---
(From update of attachment 116030)
View in context: https://bugs.webkit.org/attachment.cgi?id=116030&action=review

> Source/JavaScriptCore/jit/JITArithmetic32_64.cpp:632
> -    addSlowCase(branchAdd32(Overflow, regT2, regT0));
> -    emitStoreInt32(dst, regT0, (op1 == dst || op2 == dst));
> +    Jump overflow = branchAdd32(Overflow, regT2, regT0, regT3);
> +    emitStoreInt32(dst, regT3, (op1 == dst || op2 == dst));
> +    end.append(jump());

This change means that overflow is no longer counted by the RareCaseProfile, which will lead to potentially disastrous performance regressions in DFG.

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