[llvm] [VPlan] Expand AddRecs in Plan's entry (PR #209921)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

Could you rebase on top of current `main`? I think we now have a good understanding where VPlan expansion can lead to some small missed CSE opportunities and this should be good to go

https://github.com/llvm/llvm-project/pull/209921