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

[Ehsan Amiri via llvm-commits]

amehsan wrote:

I  have probably made a mistake in the last three comments. I ignored the key point that the subscript might be nsw/nuw under some condition but not nsw/nuw in the entire space.

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