Using the War Thunder game on Slackware, Mesa git custom compiled, LLVM 4.0 and
on a RV710 card (512MB video RAM) always produces visual errors. The errors are
not the same at all runs but vary between these problems, e.g. sky being black,
clouds being any color, water is some color without reflections, trees being
blue.
Plane/ground target models are mostly correct, but sometimes they are also
white.

The errors can be seen right in the hangar, but also when playing the game (in
a mission).

I have set the "Old videocard support" in the graphics options in the game.
This has improved things to the state I describe. The game client shows "ultra
low quality" in the right hand corner. I am using the low-res client (HD
textures not downloaded) and the client often prompts to download hi-res
textures which I decline.

Other than this, the game runs correctly, albeit slow on this GPU (5-15FPS).

In the console where I start the game (updater binary) there is a ton of output
like:
EE r600_shader.c:183 r600_pipe_shader_create - translation from TGSI failed !
EE r600_state_common.c:803 r600_shader_select - Failed to build shader variant
(type=1) -1

The line numbers 183 and 803 are always the same.