[llvm] [GlobalOpt][FMV] Fix static resolution of calls. (PR #160011)

[Alexandros Lamprineas via llvm-commits]

labrinea wrote:

Update: I found another bug in the algorithm and came up with a fix (the candidate index `I` needs to be recalculated for each caller version). The complexity of using `KnownBits` is cubic: O(M x M x N), where M is num of caller versions and N is num of callee versions. We discussed the tradeoff between accuracy and overhead with @momchil-velikov and we think it is probably not worth it. I am inclined to revert the `KnownBits` logic.

https://github.com/llvm/llvm-project/pull/160011