[llvm] [CVP] Check whether the default case is reachable (PR #79993)

[via llvm-commits]

eaeltsin wrote:

Heads-up - this might be the reason for the significant increase of generated protocol buffers compilation times (~5x).

We are looking for a reproducer, but maybe you have ideas right away?


https://github.com/llvm/llvm-project/pull/79993