[Webkit-unassigned] [Bug 64068] DFG JIT unnecessarily boxes and unboxes values during silent spilling

Thu Jul 7 15:45:40 PDT 2011

https://bugs.webkit.org/show_bug.cgi?id=64068

Gavin Barraclough <barraclough at apple.com> changed:

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--- Comment #2 from Gavin Barraclough <barraclough at apple.com>  2011-07-07 15:45:40 PST ---
(From update of attachment 99951)
Hi Filip, I think there may be a subtle bug in this code.  When a register is silently spilled it is only actually written out to memory if it needs to be spilled (hasn't already been).  This means that if you have values in registers XMM0 & XMM1, and XMM0 has already been spilled as a boxed value, then after the silent spill one of the values in memory will be boxed and the other won't.  As such, you need to handle this in the silentFillFPR.  If the register needsSpill() then it is unboxed, if not the value in memory is boxed.  Also, please expand on the ChangeLog entry.

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