[llvm] [Mem2Reg] Generate non-terminator unreachable for !noundef undef (PR #96639)

[Nikita Popov via llvm-commits]

nikic wrote:

> LGTM. Can we also do this for SROA?

SROA uses mem2reg internally, so this *mostly* also covers SROA as well (apart from one edge case...)

https://github.com/llvm/llvm-project/pull/96639