It seems that the NVIDIA drivers leaves VBVs bindings untouched
when they are NULL (or the GPU buffer address is NULL), instead of
setting them to a null binding.
Differently from other cases of inconsistent behaviour between AMD
and NVIDIA, here I'm explicitly marking the NVIDIA behaviour as
broken, because the expected behaviour is spelled out explicitly
(at least for the D3D12 specification standards).
The code doesn't make sense in the first place, even if it's
accepted by the compiler, so it makes sense that the behaviour
is undefined. And indeed the behaviour is different on AMD (4 is
returned), NVIDIA (QNaN is returned) and WARP (device is removed).
The stride didn't match the structure size used in the shader.
This didn't seem to be a problem on AMD and WARP, but it was
on NVIDIA on Windows. Specifically, it seems that the buffer
is read using the shader structure size (so most tests pass),
but bounds are checked using the buffer stride, so a test
returned zero simply because an out-of-bounds read was detected.
Unless the D3D11_FEATURE_DATA_D3D11_OPTIONS2.MapOnDefaultTextures
feature is supported, textures with default usage cannot be read by the
CPU; and there isn't a need to either, since we're going through a
staging texture anyway.
This worked on AMD and WARP, but failed on NVIDIA on Windows.
