[llvm] [TableGen] Use guarded assert in constexpr functions (PR #194728)

[Sergei Barannikov via llvm-commits]

s-barannikov wrote:

AFAIK the only purpose of llvm_unreachable after a fully covered switch statement is to make MSVC happy. Other compilers are happy without it (not sure about constexpr functions though).


https://github.com/llvm/llvm-project/pull/194728