[PATCH] D84399: [SCEVExpander] Avoid re-using existing casts if it means updating users.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


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Comment at: llvm/lib/Transforms/Utils/ScalarEvolutionExpander.cpp:112
+  // If we skipped past MustDominate, use MustDominate as insertion point.
+  if (IP->getParent() == MustDominate->getParent() &&
+      !IP->comesBefore(MustDominate))
----------------
I'm not sure I understand what's happening here. "I" dominates "MustDominate" because the we're inserting an instruction that uses I. And we're assuming MustDominate itself must be a legal insertion point. So the only way we could skip past MustDominate is if IsInsertedInstruction() is true for MustDominate.

Is it actually possible for isInsertedInstruction(MustDominate) to be true? If it is, could we check it directly?


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  https://reviews.llvm.org/D84399/new/

https://reviews.llvm.org/D84399