It seems that the new Crimson driver has introduced an issue with CodeXL (versions 1.8 and 1.9 tested, both on Windows) - when GLSL code contains a call to texture() or similar, several lines of the ISA code are overwritten with V_NOP.
You can test the issue with any short shader that contains a texture() call - the only output will be lots of V_NOP. With longer shaders that have a lot of non-texture commands, only the first chunk of instructions are overwritten.
I noticed in the CodeXL 1.9 changelog that a fix for an issue that sounds exactly like this was made for Ubuntu. I think the same fix is needed on Windows.
I've also noticed that this only happens in fragment shaders - vertex or tessellation shaders with texture fetches do not appear to be affected
If it helps I've observed the behaviour on 2 different machines, one on 8.1 with a 7770 and the other on 10 with an R9 290, both x64
Thanks again. We will do our best to get it fixed for the next version.
We will contact you personally soon to provide a local workaround.