[llvm] [VPlan] Add initial CFG simplification, removing BranchOnCond true. (PR #106748)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

This patch now depends on both https://github.com/llvm/llvm-project/pull/110577 and https://github.com/llvm/llvm-project/pull/109975 which helps to simplify the patch as there's no need to manually remove live-outs or manually update phis in the scalar ph which previously have been created during skeleton construction outside VPlan.

It probably only makes sense to review the patch once https://github.com/llvm/llvm-project/pull/110577 and https://github.com/llvm/llvm-project/pull/109975 landed

https://github.com/llvm/llvm-project/pull/106748