Comment # 3 on bug 93447 from Ilia Mirkin

(In reply to Grazvydas Ignotas from comment #2)
> I believe this bug can also be triggered by radeonsi though, as it also
> calls radeon_llvm_emit_prepare_cube_coords(). When target ==
> TGSI_TEXTURE_CUBE and opcode == TGSI_OPCODE_TXF, si_shader.c will take and
> use garbage value from that function.

You can't texelFetch() on a samplerCube.