[llvm] [VPlan] Add ExtractLane VPInst to extract across multiple parts. (PR #148817)

[David Sherwood via llvm-commits]

https://github.com/david-arm requested changes to this pull request.

Hi @fhahn, sorry to do this but I think the lane calculation when interleaving is broken at the moment.

https://github.com/llvm/llvm-project/pull/148817