Beyond that though, I imagine part of the motivation is also simplifying the DXIL parser, right? How much does this help there?
I'm also doubting its worth, because if we modify `emit_ftoi()` and `emit_ftou()`, the DXIL parser doesn't need to emit double instruction variants at all.
I imagine we'll also need some changes to the d3d-asm output in order to distinguish between e.g. ADD on VKD3D_DATA_FLOAT sources and ADD on VKD3D_DATA_DOUBLE sources.
I was thinking of doing this where double is used with non-double instructions. If we don't normalise TPF it would only change the disassembly of DXIL shaders.