[PATCH] D43876: [LoopUnroll] Peel off iterations if it makes conditions true/false.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


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Comment at: lib/Transforms/Utils/LoopUnrollPeel.cpp:154
+  unsigned DesiredPeelCount = 0;
+  PHINode *IndVar = L->getCanonicalInductionVariable();
+  if (!IndVar)
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Please don't use getCanonicalInductionVariable; indvars doesn't generate canonical induction variables anymore, so this will only handle limited cases.

Can you use SCEV here instead?


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Comment at: lib/Transforms/Utils/LoopUnrollPeel.cpp:177
+      if (Bound <= MaxPeelCount)
+        DesiredPeelCount = std::max(DesiredPeelCount, Bound);
+    }
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This doesn't check for the possibility that the induction variable could wrap... not a correctness problem, of course, but it's not clear the transform is profitable in that case.


https://reviews.llvm.org/D43876