Created attachment 67592 [details]
apitrace

Attached is an apitrace, and screenshots.

Bad behaviour with --enable-r600-llvm-compiler:
OpenGL vendor string: X.Org
OpenGL renderer string: Gallium 0.4 on AMD RV730
OpenGL version string: 3.0 Mesa 9.1-devel (git-fb40f88)
OpenGL shading language version string: 1.30

If you look at the 'bad.png' screenshot you'll see that the 4th column is light
blue. It should be grey.
With R600_LLVM=0 the good behaviour is seen: good.png.

See the apitrace for the full shader, here is the relevant bit:
    else if (gl_FragCoord.x < 640)
        color = vec4(1.0f, 1.0f, 1.0f, 1.0f);//white
    [...]
        vec4 color0, color1, color2, color3;
        if (gl_FragCoord.y < 200) {
            color0 = color1 = color2 = color;//75%
   [...]
        } else if (xmod < 55 || xmod >= 105 ||
                   ymod < 75 || ymod >= 125) {
            // real color
            // TODO: buggy on r600g with LLVM?
            gl_FragColor = (color0 + color1 + color2 + color3) / 4.0f;

P.S.: the shader is not optimal, most of the branches could be moved out of it,
I haven't tried to minimize the testcase though.