Re: [PATCH 0/1] MR368: vkd3d-shader: Add constant folding for 'rsq'.

[Giovanni Mascellani (＠giomasce)]

Giovanni Mascellani (@giomasce) commented about libs/vkd3d-shader/hlsl_constant_ops.c:
> -
>                            "Floating point division by zero.");
> -
>            }
> -
>            dst->u[k].f = 1.0f / sqrtf(src->value.u[k].f);
> -
>            if (ctx->profile->major_version < 4 && !isfinite(dst->u[k].f))
> -
>            {
> -
>                hlsl_error(ctx, loc, VKD3D_SHADER_ERROR_HLSL_NON_FINITE_RESULT,
> -
>                        "Infinities and NaNs are not allowed by the shader model.");
> -
>            }
> -
>            break;
> -
> -
>        case HLSL_TYPE_DOUBLE:
> -
>            if (src->value.u[k].d < 0.0)
> -
>            {
> -
>                hlsl_warning(ctx, loc, VKD3D_SHADER_WARNING_HLSL_IMAGINARY_NUMERIC_RESULT,
> -
>                        "Imaginary square root result.");
> -
>            }

Why there is no warning for zero in this case? BTW, did you manage to actually have native execute `rsqrt()` on a `double`? If I try something trivial as
```hlsl
float4 main(uint4 x : COLOR) : sv_target
{
    double y = 0.0;
    return rsqrt(y);
}
```
the warnings seem to imply that `y` is casted to `float` before being given to `rsqrt()`.