Bug 152447 – Snippefy op_negate for the baseline JIT.

• Status: RESOLVED
• Resolution: FIXED
• Component: JavaScriptCore

[Mark Lam]

Patch coming.

[Mark Lam]

Created attachment 267756 [details]
proposed patch.

Benchmarking shows that perf is neutral when the DFG is enabled.  I still need to run perf numbers for when the DFG is disabled.

[Mark Lam]

Created attachment 267757 [details]
x86_64 benchmark result.

[Mark Lam]

Created attachment 267758 [details]
x86 benchmark result.

[Mark Lam]

Created attachment 267769 [details]
x86_64 benchmark result without DFG.

[Mark Lam]

Created attachment 267770 [details]
x86 benchmark result without DFG.

[Mark Lam]

All perf results are neutral.  This patch is ready for a review.

[Benjamin Poulain]

Comment on attachment 267756 [details]
proposed patch.

View in context: https://bugs.webkit.org/attachment.cgi?id=267756&action=review

> Source/JavaScriptCore/jit/JITNegGenerator.cpp:56
> +    m_endJumpList.append(jit.jump());

Why do you have a "m_endJumpList" used by the user of this object?...

> Source/JavaScriptCore/jit/JITNegGenerator.cpp:67
> +#endif

...Instead of linking the jump here after the Double case?

[Mark Lam]

Comment on attachment 267756 [details]
proposed patch.

View in context: https://bugs.webkit.org/attachment.cgi?id=267756&action=review

>> Source/JavaScriptCore/jit/JITNegGenerator.cpp:67
>> +#endif
> 
> ...Instead of linking the jump here after the Double case?

This is to enable an optimization.  If you search in DFGSpeculativeJIT.cpp for "gen.endJumpList().append(m_jit.jump());", you will see cases where the DFG wants to place some slow path code immediately after snippets emit their code.  By having an endJumpList(), we can avoid the cases where the internal of snippets jump to the snippet end, only to jump over some slow path code in the client to the real end point.  The endJumpList allows that the snippet code to jump to the real end point as determined by the client.

[Mark Lam]

Thanks for the review.  Landed in r194363: <http://trac.webkit.org/r194363>.