Re: [RFC PATCH] target/ppc: do not silence snan in xscvspdpn

[Matheus K. Ferst]

On 13/12/2021 12:46, Richard Henderson wrote:
> On 12/13/21 4:13 AM, matheus.ferst@eldorado.org.br wrote:
> > From: Matheus Ferst <matheus.ferst@eldorado.org.br>
> >
> > The non-signalling versions of VSX scalar convert to shorter/longer
> > precision insns doesn't silence SNaNs in the hardware. We are currently
> > honoring this behavior in xscvdpspn, since helper_xscvdpspn handles the
> > conversion with extracts/deposits/etc. OTOH, xscvspdpn uses
> > float32_to_float64 that calls parts_float_to_float, which uses
> > parts_return_nan that finally calls parts_silence_nan if the input is an
> > SNaN.
> >
> > To address this problem, this patch adds a new float_status flag
> > (return_snan) to avoid the call to parts_silence_nan in the
> > float_class_snan case of parts_return_nan.
> >
> > Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
>
> I think you shouldn't be using softfloat at all for this, but use the 
> existing
> helper_todouble function.

Oh, that's better, I'll send a v2.

Thanks,
Matheus K. Ferst
Instituto de Pesquisas ELDORADO <http://www.eldorado.org.br/>
Analista de Software
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