(In reply to Samuel Pitoiset from comment #7)
> A temporary workaround is to use R600_DEBUG="nodccfb".

Does the existence of this workaround mean you do not intend to fix the bug? 
Given that there have been 2 17.2 releases (and 17.3 is in rc2) since this was
written, and the bug is still present, I guess so.  Gentoo is making it really
hard to retain my own workaround (don't upgrade to 17.2) due to its dependency
on llvm-4, so I guess I'll just have to live with your workaround.