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

[Nikita Popov via llvm-commits]

nikic wrote:

> Why not use `call void @llvm.assume(i1 false)`? If I understand correctly, this should be the more canonical approach?

Store to poison is the canonical form for non-terminator unreachable. In fact, InstCombine will convert assume(false) to it: https://llvm.godbolt.org/z/rsfd7hzja

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