[Webkit-unassigned] [Bug 116306] MacroAssemblerARM should use xor to swap registers instead of move

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Mon May 27 21:09:13 PDT 2013


https://bugs.webkit.org/show_bug.cgi?id=116306





--- Comment #7 from Filip Pizlo <fpizlo at apple.com>  2013-05-27 21:07:44 PST ---
(In reply to comment #5)
> (In reply to comment #1)
> > Maybe we should consider to make this change on ARMv7 as well.
> 
> I think we should not.
> ARMv7 has register aliasing, making "mov" essentially free in most situation.
> 
> Does the bug exist on ARMv7 though?

Yeah this doesn't feel right for the ARMv7 assembler. There we have scratch registers for doing this. So long as there is a spare register the moves will be faster.

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