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Re: [RFC PATCH, x86_64] Use -mno-sse[,2] to fall back to x87 FP argument passing convention


> Hello Michael!
> 
> >> In current state of x86_64 affairs, user can select -mfpmath=387 to
> >> instruct the compiler to use x87 FP instructions.
> >
> >FWIW, I think -mfpmath=387 should actually give an error with -m64.  I
> >want all traces of x87 to die a silent death.  For x86 that's impossible,
> >we should not do anything to make it impossible for x86-64.
> 
> XFmode arguments use x87 registers on x86-64. It looks that x87 will
> be with us for a long time...

Ineed :(
However I would still preffer -mno-sse to not silently change ABI and
instead give user nice friendly error message.  We may introduce some
kind of attribute, just like we have regparm to enforce x87 passing
convention but I don't see much real use for it...

Honza
> 
> Uros.


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