https://bugs.freedesktop.org/show_bug.cgi?id=88522
--- Comment #6 from almos aaalmosss@gmail.com --- I no longer have the HD6850 card, unfortunately. With my new card (R9 270x) and recent software stack (kernel 4.3.3, mesa 11.1.1, llvm 3.7.1) this demo runs perfectly.