[PATCH] D65474: [SCEV] Return zero from computeConstantDifference(X, X)

[Sanjoy Das via Phabricator via llvm-commits]

sanjoy requested changes to this revision.
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> We use computeConstantDifference in some downstream code, and I was surprised to find out that it fails to compute (X - X) difference, unless X is a SCEVAddExpr.

Can you use `getMinusSCEV` instead (which should DTRT)?

This looks like a small change, having many such cases (especially without unit tests) makes it difficult to refactor code confidently.


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  rL LLVM

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https://reviews.llvm.org/D65474