Right. I guess the question is what that would look like. One approach would be to output ADD with VKD3D_DATA_DOUBLE as DADD. At that point we could arguably just as well just emit a DADD in the first place from the DXIL parser though. Another approach would be to just include type information in the output for shader model 6+, much like DXIL assembly does. There would be some choices to make there as well; e.g., we could always switch this based on the shader model, but we could also make this a formatting option, which would allow displaying these for e.g. TPF shaders as well.
In the interest of making it easier to use VSIR as an IR, it would certainly be useful to have a way to dump it in a way which doesn't have too much of a TPF-colored lens on it. I.e., some typing information, a more regular printout of indices; I might be wrong, but I guess that current the disassembler only prints instruction/register/index combinations which make sense in D3DBC/TPF, while we probably would like to have more freedom on that at some point.