[llvm] [LAA] Rewrite findForkedPointer, fixing freeze (PR #140298)

[Ramkumar Ramachandra via llvm-commits]

https://github.com/artagnon commented:

Have to think about this a little bit, because I'm not sure what the correct freeze logic should be, and if findForkedSCEVs is setting freeze incorrectly. The previous code's freeze logic seems clearly incorrect though.

https://github.com/llvm/llvm-project/pull/140298