[PATCH vkd3d] vkd3d-shader/hlsl: Handle constant value operations on a different file.

[Giovanni Mascellani]

Hi,

Il 19/01/22 13:10, Matteo Bruni ha scritto:
> Another one that potentially needs some care is folding float
> expressions. E.g. even transforming a "(x + a) + b" into "x + (a + b)"
> (with x float, a and b constants) can technically affect the final
> result, depending on the specific values.
> We need to replicate MS's compiler in this regard, or at least support
> compatible behavior as one of the options. I've been looking into this
> a bit and it appears that the native compiler always allows constant
> folding transformations, regardless of the presence of the precise
> keyword or the D3DCOMPILE_IEEE_STRICTNESS flag to D3DCompile(). Other
> transformations / optimizations are affected but I guess we'll think
> about those when we get there.
> 
> So, as far as constant folding is concerned, always optimizing float
> constants should be okay. Or we could have our own compilation flag to
> control that, in case we feel that behavior might be useful to some
> non-Wine user.

I am not completely sure of what you mean here. You say that you fear 
that if we have "(x + y) + z" with x, y and z constants, native compiler 
could transform this to "x + (y + z)" before doing constant folding?

Giovanni.