[llvm] [SelectOpt] Optimise big select groups in the latch of a non-inner loop to branches (PR #119728)

[David Green via llvm-commits]

davemgreen wrote:

This sounds like a bit like tail-duplication if the latch has a select that is profitable to convert. This probably doesn't apply to larger loop latches though, is it possible to represent it in terms of tail duplication and limit it to relatively small latches where the select is dominating?

https://github.com/llvm/llvm-project/pull/119728