(In reply to comment #6)
> Not an LLVM issue, just hung with a downgraded LLVM 3.4.

Note that it's not really supported for the radeonsi driver to run against a
version of LLVM older than the one it was built against. It might be good to
confirm that old Mesa with LLVM 3.4.2 isn't affected by the problem.

> So the problem has to be in mesa. I will now try to find the latest working
> version of mesa. Starting from 10.1.4 for now.

Thanks, but FWIW, the most helpful thing you could do would be to bisect the
problem from upstream Mesa Git.