[PATCH v3 2/5] d3dcompiler: Add stub ID3D12ShaderReflection interface.

[Paul Gofman]

On 9/1/20 17:43, Matteo Bruni wrote:
> On Tue, Aug 11, 2020 at 2:31 PM Paul Gofman <pgofman at codeweavers.com> wrote:
>> Signed-off-by: Paul Gofman <pgofman at codeweavers.com>
>> ---
>> v2:
>>      - fix reflection test in d3d10.
>> v3:
>>      - show in test that QueryInterface between ID3D11.../ID3D12ShaderReflection returns the same interface pointer.
> I had also noticed that the d3d11 and d3d12 interfaces coincide. It's
> an implementation detail and it seems very unlikely that any
> application depends on it, thus your implementation is certainly fine
> as far as I'm concerned. I'm curious though how would it look without
> the duplication. GetResourceBindingDesc[ByName]() will need some care,
> but that's the case either way.
> Bottom line, I'd like to see some patches for the alternative version
> and, if it doesn't look too terrible, probably go with that. If you
> already tried and it didn't feel right that's good enough for me.

I did not make such patches, but the idea is very simple. The only 
binary difference between interfaces is in 
d3d11_shader_reflection_GetResourceBindingDesc() method: d3d12 version 
of _SHADER_INPUT_BIND_DESC is longer. We could store the structure size 
in the reflection structure from D3DReflect() based on requested 
interface name. Then, just return existing ID3D11ShaderReflection 
interface for d3d12, and modify 
d3d11_shader_reflection_GetResourceBindingDesc to copy the result to 
output based on the stored length. As far as I interpret the tests, that 
is exactly what the native implementation is doing. I honestly don't see 
anything terrible about casting the interface in this case, given it 
saves so many lines and matches native behaviour.