Every time I’ve upgraded from the 78 series of drivers, I see the same GLSL bug, and I have to downgrade.
I’m writing to a varying mat3 in my vertex shader, but the results are not propagating correctly.
If I replace the varying mat3 with writes to
gl_TexCoord[1…3].xyz, the problem disappears.
I never get an error or warning that I’ve run out of varying variables.
An aside: the 84.xx drivers seem to randomly eventually crash at MakeCurrent calls.