Re: [Qemu-devel] [PATCH v2 01/20] softfloat: fix floatx80 handling of NaN

[Peter Maydell]

On 20 April 2011 11:11, Aurelien Jarno <address@hidden> wrote:
> @@ -624,10 +630,11 @@ static floatx80 commonNaNToFloatx80( commonNaNT a 
> STATUS_PARAM)
>         return z;
>     }
>
> -    if (a.high)
> -        z.low = a.high;
> -    else
> +    if (a.high >> 1) {
> +        z.low = LIT64( 0x8000000000000000 ) | a.high >> 1;
> +    } else {
>         z.low = floatx80_default_nan_low;
> +    }
>     z.high = ( ( (uint16_t) a.sign )<<15 ) | 0x7FFF;
>     return z;
>  }

This is still retaining the sign bit from the input if it generates
a default NaN because the mantissa would have been zero. This isn't
consistent with the commonNaNToFloat64/32, which just return the
float64/32_default_nan with whatever sign it has.

-- PMM