[PATCH] D147117: [SCEV] When computing trip count, only zext if necessary

[Nikita Popov via Phabricator via llvm-commits]

nikic added inline comments.


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Comment at: llvm/lib/Analysis/LoopCacheAnalysis.cpp:337
   if (auto ConstantCost = dyn_cast<SCEVConstant>(RefCost))
-    return ConstantCost->getValue()->getSExtValue();
+    return ConstantCost->getValue()->getZExtValue();
 
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The changes to LoopCacheAnalysis should be split out into a separate patch. I'm also wondering why this changes some but not all of the AnyExtends...


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Comment at: llvm/lib/Analysis/ScalarEvolution.cpp:8047
+  const SCEV *One = getOne(ExitCountType);
+  if (!Extend || willNotOverflow(Instruction::Add, false, ExitCount, One))
+    return getAddExpr(ExitCount, One);
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I'd prefer this to go back to the previous version. willNotOverflow() is very expensive and not needed here.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D147117/new/

https://reviews.llvm.org/D147117