[PATCH] D128877: [LoopCacheAnalysis] Fix a type mismatch bug in cost calculation

[Michael Kruse via Phabricator via llvm-commits]

Meinersbur added a comment.

I don't think we can rely on `isKnownNegative`

1. The SCEV might be sometimes negative, sometime positive, depending on some runtime value (e.g. stride is multiplied by a function argument). This is, if `isKnownPositive` and `isKnownNegative` both return false, we'd need to bail out.
2. `isKnownNegative` already assumes that the integer is signed. With that assumption, `sext` would always be correct (which is equivalent to zext for positive integers)


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https://reviews.llvm.org/D128877