[llvm] [VPlan] First step towards VPlan cost modeling. (PR #67934)

[Florian Hahn via llvm-commits]

fhahn wrote:

Ping. All pending patches landed now and I just updated this PR to current main, as well as the one with the alternative structure https://github.com/llvm/llvm-project/pull/92555

https://github.com/llvm/llvm-project/pull/67934