[llvm] [SCEV] Restrict wrap flags when construction same AR for multiple phis. (PR #80430)

[Eli Friedman via llvm-commits]

efriedma-quic wrote:

I'm also skeptical this is right.  nowrap on an AddRec means the value can't wrap by construction, i.e. based on an upper bound on the trip count of the loop.  The only overflow flags that are relevant are flags which allow narrowing that upper bound.

https://github.com/llvm/llvm-project/pull/80430