I don’t know the stack deep enough and Blender even less, so hopefully Brecht can help you more.
There is no real magic in the drivers, the stack is almost completely open on github and the packages available for download. Only one or two obscure packages are proprietary.
Building the stack was a few years ago a nightmare, now it is almost acceptable - still very rough.
Maybe this can help you, on top of the official drivers:
- this script from an AMD engineer builds almost all the stack with just cmake.
- I adapted his script to build on Debian with vanilla LLVM - AMD have forked LLVM
- I also made a builder for Debian packages here.
From there enabling the tests and tinkering with them is pretty easy.
There are also Gentoo and Arch packages.