I also still get hangs, but they seem to be less frequent than they used to be.
However, the framerate seems to be a bit lower compared to the last time I
tested - ~70 vs. (iirc) 80+ FPS in the menu - so maybe it's just that. Both the
game and glamor were using the updated Mesa version.

Curiously, the first freeze I got when testing didn't look like a GPU lockup
but rather a (partial) X server lockup: all blocks were at 0% in radeontop and
I was able to switch to a different VT using Ctrl+Alt+F1, and while switching
back to X blocked further VT switches I was able to restart the X server
normally (the log indicated a clean shutdown) and everything including OpenGL
seemed to work fine after that.

The freeze lockup I got was a proper GPU lockup though - Event Engine and
Texture Adresser at 0%, everything else at 100%, unable to switch VTs even with
chvt over ssh.

Kernel: 4.7.0-gentoo
Mesa: git-50b49d2
LLVM: r278309