[discuss] RFC: Support IEEE 754R draft in the x86-64 psABI

Jan Hubicka jh at suse.cz
Sat May 6 00:35:53 CEST 2006


> Hi, HJ.
>  
> > There is an IEEE 754R draft for decimal floating-point 
> > arithmetic. We'd like to extend the x86-64 psABI to support 
> > it. The x86-64 psABI needs to be updated to:
> 
> Extending the x86-64 psABI to support IEEE754r DFP is a welcome improvement to the x86-64 platform.  We will be happy to work with the community to develop and refine the proposal and ultimately secure final approval.

Yep.  Also are there any plans on GCC implementation?

> 
> > 1. Define new types for decimal floating-point.
> 
> OK.  The current types implemented in GCC 4.2, _Decimal{32|64|128}, are perhaps good starting points.  The question remains which types could be optional and which should be mandatory, without violating IEEE754r.

Is there any reason for making any of these types mandatory?

> 
> > 2. Specify how decimal floating-point parameters are passed.
> 
> There already is something in place in the CVS head version of the psABI concerning the DFP types specifying XMM registers to pass or return them, akin to same-sized FP types.

Yes, this should be solved by that already.
I will look into the draft concerning the library function naming
convention.

Honza



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