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

[Richard Henderson]

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.


r~