[llvm] [TableGen] Complete the support for artificial registers (PR #183371)

[Ivan Kosarev via llvm-commits]

kosarev wrote:

> And you configured with `-DLLVM_ENABLE_EXPENSIVE_CHECKS=ON` ?

Yes. I used to catch exactly this kind of problems myself: https://github.com/llvm/llvm-project/issues/68594

https://github.com/llvm/llvm-project/pull/183371