[llvm] [polly] [SCEV] Introduce SDiv expressions (PR #216862)

[Antonio Frighetto via llvm-commits]

https://github.com/antoniofrighetto commented:

> Can you suggest a better way?

I think the approach taken here is fine in principle, so long as we are able to demonstrate that the trade-off between the added complexity and the refined precision is worth it.

https://github.com/llvm/llvm-project/pull/216862