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Re: -mno-80387 and MMX autovectorisation


On Thu, Jun 08, 2006 at 08:50:13AM -0700, Andrew Pinski wrote:
> 
> On Jun 7, 2006, at 11:13 PM, Uros Bizjak wrote:
> 
> >Hello!
> >
> >Current mainline gcc can efficiently disable x87 instruction when
> >-mno-80387 switch is used. In this case, MMX registers can be used for
> >the autovectorisation even without emms or femms instructions to
> >switch back to x87 mode.
> 
> I don't think so, because another function could use x87 instructions
> even without you knowing it.

But it would not be difficult to check regs_ever_live[] and emit the
(f)emms instruction in the epilogue if an MMX register was ever used.

-- 
Rask Ingemann Lambertsen


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