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

[Ehsan Amiri via llvm-commits]

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amehsan wrote:

> Created a PR #170684

Thank you for posting your PR. I thought I should create a PR as well instead of an issue. It will take me a few days. The reason is that I have a couple of ideas on how to check signed BTC >= 0 and I'd like to run some experiments see what kind of code exists in real programs. Also I may  need to check somethings in SCEV code. Thanks again.

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