What is the "secondary data" passed to D3DCompile2?

Question

With the release of Visual Studio 2012, Microsoft added the D3DCompile2 API, a new version of D3DCompile. The only difference is that D3DCompile2 takes some additional parameters relating to some "secondary data". The nature of this data is not discussed in the documentation, and googling around has turned up nothing about it.

What is this "secondary data" accepted by D3DCompile2, where might it come from and what is it used for?

Answer 1

It exists for a special purpose of getting two different DirectCompute shaders to use exactly the same UAV alignment. It's kinda of a hack, so just ignore it, pass nullptr/0, and move along :)

I have filed a bug to make sure the MSDN doc page is more clear about it...