When compiling, the compiler will detect unused registers and kick them. This is great to be able to check what is actually used by the shader, but unfortunately that also prevents us from having stable shader reflection. If the shader artist connects a variable that is now compiled out, it would break their workflow. And if another variable is now not compiled out they'll have to connect it again. It would be great if O0 or a flag to avoid stripping this is available. Because right now we rely on manually tokenizing and parsing the entire file.