[llvm] [Analysis][NFC] Use block numbers for BranchProbabilityInfo (PR #186658)

[Alexis Engelke via llvm-commits]

aengelke wrote:

> Storing things like this would make it hard to do incremental updates for CFG changes,

I don't quite follow. Incremental updates of the analysis are possible as before, as long as there's no renumbering. The Probs array grows monotonically, but if this becomes a problem, it could be easily compacted. I didn't implement this, because BPI is usually quite short-lived.

https://github.com/llvm/llvm-project/pull/186658