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

[Ryotaro Kasuga via llvm-commits]

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kasuga-fj wrote:

> If we rely on SCEV behavior, I may be able to simplify my proofs too. Let me check if it is possible.

I'm not sure why you are so obsessed with your proofs. I say they are unnecessary. If you want to save your time, I'd recommend pausing it for now.

> Also I need to look into the compile time issue a little more.

I measured the compile time by enabling loop-interchange. There was almost no difference.

https://llvm-compile-time-tracker.com/compare.php?from=d6d1b81367979a372f8aad26fee7390f786c81da&to=0bdb7035a2d5ba4b754a071a57b4d376619e8e11&stat=instructions:u

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