- Implement VTEmitter as llvm-tblgen -gen-vt.
- Create a copy of llvm/Support/MachineValueType.h into unittests/Support. It includes GenVT.inc generated by VTEmitter.
- Implement MVTTest in SupportTests. It checks equivalence between llvm/Support/MachineValueType.h and the generated header.
Depends on D146907
auto is longer than MVT, just declare the type