[llvm] [VPlan] Handle early exit loops with non-dereferenceable loads in latch (PR #172454)

[Luke Lau via llvm-commits]

lukel97 wrote:

Moving to a draft for now, will rework on top of #176143 so it can share the code for splitting the control flow + keeping SSA + handling live outs.

https://github.com/llvm/llvm-project/pull/172454