The fact that we can potentially have passes that should be called on both `vkd3d_shader_normalise_sm4()` and `vkd3d_shader_normalise_sm6()`, such as `remove_dcl_temps()` in 3/3 may be an argument against separating the function, but I don't know if we will end up with enough for the repetition to be a problem.
Yeah, I guess it's still a bit early to commit on that decision. Right now both alternatives look essentially equivalent.