[PATCH] D116499: [SCEV] Compute exit count from overflow check expressed w/ x.with.overflow intrinsics

[Nikita Popov via Phabricator via llvm-commits]

nikic accepted this revision.
nikic added a comment.
This revision is now accepted and ready to land.

LG with some nits



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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:8101
+    if (EVI->getNumIndices() == 1 && EVI->getIndices()[0] == 1)
+      if (auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand())) {
+        const APInt *C;
----------------
I'd write these three conditions as `match(ExitCond, m_ExtractValue<1>(m_WithOverflowInst(WO))`.


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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:8111
+          if (!ExitIfTrue)
+            Pred = ICmpInst::getInversePredicate(Pred);
+          auto *LHS = getSCEV(WO->getLHS());
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I didn't spot where this case is tested. Can you please add one where the successors are swapped? I see some tests using `xor -1`, but that doesn't appear to be supported by SCEV right now.


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