[llvm] [VPlan] Record estimated branch probabilities on VPlan0 for cost modeling (PR #216172)

[Florian Hahn via llvm-commits]

fhahn wrote:

> Having to store an estimated field in the execution frequency is a bit strange, it would be good to untangle the block frequencies used for costing and the block frequency used for preserving branch probability metadata. But I don't really have any better ideas.

Yeah, unfortunately I also could not think of a better way to avoid generating `!prof` metadata from estimates.

https://github.com/llvm/llvm-project/pull/216172