[llvm] [LoopVectorize] Ensure VPPredInstPHIRecipe only uses InsertElementInst (PR #159543)

[Abhinav Srivastava / August Radjoe via llvm-commits]

AbhinavMir wrote:

@fhahn I absolutely got crushed with some work, haven't been able to focus here. I wasn't able to solve it correctly, as I feel I don't know LLVM well enough yet. I may have to leave this in draft. I am currently going through your other comment. Sorry!

https://github.com/llvm/llvm-project/pull/159543