Ryzen 1600X, 16GiB RAM, AMD RX570, Fedora 26 (clean install)

mesa-dri-drivers-17.1.7-1.fc26

Unigine Superposition Benchmark v1.0 (build 6184) Basic

Superposition and other OpenGL 4 (I guess) applications fail to render
correctly. It seems that only one of the rendering stages is being shown -- it
looks like the specular highlights from a cubemap or similar.

Tacoma (running on Unity) does the same.

Furthermore, there is a large disparity between the reported frame rate (30+)
and the actual frame rate I see (perhaps 1/3 or 1/4 of that).

Both worked perfectly in Fedora 25 (same hardware) with
mesa-dri-drivers-17.0.5-3.fc2.

I'm guessing this is a problem in the radeonsi driver.