(In reply to Marek Olšák from comment #3)
> I think you forgot to install drirc from Mesa. What happens if you set this
> env var?

No, I have correct drirc.

> 
> allow_glsl_extension_directive_midshader=true

Setting this env variable doesn't help.

(In reply to Michel Dänzer from comment #1)

> Can you try a newer kernel?

I just tried 3.17.0:

- GPU still hangs if ARB_sample_shading is not disabled.

- It seems lockup detection timeout was increased significantly:

kernel: radeon 0000:01:00.0: ring 0 stalled for more than 91985msec
kernel: radeon 0000:01:00.0: GPU lockup (waiting for 0x000000000000e90a last
fence id 0x000000000000e8fb on ring 0)

- Unrelated to this bug, but.. animation is VERY choppy. I constantly see
several-seconds-long freezes, and sometimes >10 sec long freezes.