Here's a screenshot of the bug:
I'm running an AMD R9 290 on Linux Mint 17.1, with kernel 4.0-rc5. I have bisected mesa commits and found commit f9fd0c4a55afd97fd34d0e846000c75f5f6ecac2 (http://cgit.freedesktop.org/mesa/mesa/commit/?id=f9fd0c4a55afd97fd34d0e846000c75f5f6ecac2) to be the culprit. Mesa was compiled with llvm 3.6 from the Ubuntu repositories.
Marek/Tom, any ideas?
Sqrt(x) results are undefined if x < 0, so the only thing we are allowed to do is sqrt(abs(x)). That is how RSQ works.
Can you run the program with the environment variables:
MESA_GLSL=dump PIGLIT_PLATFORM=gbm R600_DEBUG=ps,vs,gs
And post the output.
Can you still reproduce this with current Mesa git?
Anyway, this is a game bug. The game generates NaNs, which produces the artifacts. The game might have been designed for DX9 or GL2 hardware, not GL3.
It shouldn't occur anymore, because NaNs are disabled by radeonsi.
No longer seems to be happening as of 11.0.3 (914966befcd57764941405707d8f57d3e7e7f768)
Thank you to the development team.