[llvm] [DA] Add tests for nsw doesn't hold on entier iteration (PR #162281)

[Ehsan Amiri via llvm-commits]

amehsan wrote:

> we can prove that `delta != 0` implies independence for strong SIV no matter what kind of control flow we have

`delta != 0 (mod coefficient)`  This is super-important.

https://github.com/llvm/llvm-project/pull/162281