Re: [RFC PATCH 0/6] softfloat 128-bit integer support

[Richard Henderson]

On 3/28/22 14:14, matheus.ferst@eldorado.org.br wrote:
> From: Matheus Ferst <matheus.ferst@eldorado.org.br>
>
> This RFC is a first attempt at implementing the 128-bit integer
> conversion routines in softfloat, as required by the xscv[su]qqp and
> xscvqp[su]qz instructions of PowerISA v3.1.
>
> Instead of using int128.h, int-to-float routines receive the 128-bit
> numbers through a pair of 64-bit values, and float-to-int conversions
> use a pointer to return the lower half of the result.
>
> We only need the parts128 methods, but since the difference to parts64
> ones seemed minor, I included both in this patch.
>
> RFC:
>   - Should we use struct Int128 instead of 64-bit value pairs?

I think so.  We have it, and it makes the interface more obvious.

>   - I've not tested the float64 methods since the PPC instructions only
>     use the quad-precision routines. Should we keep them in the final
>     version?

Let's not add anything that we don't have a need for.
It may eventually be needed by RISC-V RV128, but we can add it then.


r~