[PATCH] D41298: [Dominators] Remove verifyDomTree add some verifing for Post Dom Trees

[Dave Green via Phabricator via llvm-commits]

dmgreen updated this revision to Diff 131605.
dmgreen retitled this revision from "[PDT] Add verifyDomTree and verifyAnalysis for Post Dom Trees" to "[Dominators] Remove verifyDomTree add some verifing for Post Dom Trees".
dmgreen edited the summary of this revision.
dmgreen added a comment.
Herald added a subscriber: mehdi_amini.

Updates. What do you think?

This exposes a bug in the DominatorTree.InsertReachable2 test that we need to sort. We may need something like this, I'm not 100%:

  diff --git a/include/llvm/Support/GenericDomTreeConstruction.h b/include/llvm/Support/GenericDomTreeConstruction.h
  index 172efb5..53387db 100644
  --- a/include/llvm/Support/GenericDomTreeConstruction.h
  +++ b/include/llvm/Support/GenericDomTreeConstruction.h
  @@ -697,25 +697,22 @@ struct SemiNCAInfo {
           }))
         return;
   
  +
       // Recalculate the set of roots.
  -    DT.Roots = FindRoots(DT, BUI);
  -    for (const NodePtr R : DT.Roots) {
  -      const TreeNodePtr TN = DT.getNode(R);
  -      // A CFG node was selected as a tree root, but the corresponding tree node
  -      // is not connected to the virtual root. This is because the incremental
  +    auto Roots = FindRoots(DT, BUI);
  +    if (DT.Roots.size() != Roots.size() ||
  +        !std::is_permutation(DT.Roots.begin(), DT.Roots.end(),
  +        Roots.begin())) {
  +      // The roots chosen in the CFG have changed. This is because the incremental
         // algorithm does not really know or use the set of roots and can make a
         // different (implicit) decision about which nodes within an infinite loop
         // becomes a root.
  -      if (TN && !DT.isVirtualRoot(TN->getIDom())) {
  -        DEBUG(dbgs() << "Root " << BlockNamePrinter(R)
  -                     << " is not virtual root's child\n"
  -                     << "The entire tree needs to be rebuilt\n");
  -        // It should be possible to rotate the subtree instead of recalculating
  -        // the whole tree, but this situation happens extremely rarely in
  -        // practice.
  -        CalculateFromScratch(DT, BUI);
  -        return;
  -      }
  +      DEBUG(dbgs() << "Roots are different in updated trees\n"
  +                   << "The entire tree needs to be rebuilt\n");
  +      // It may be possible to rotate the subtree instead of recalculating
  +      // the whole tree, but this situation happens extremely rarely in
  +      // practice.
  +      CalculateFromScratch(DT, BUI);
       }
     }
   


https://reviews.llvm.org/D41298

Files:
  include/llvm/Analysis/PostDominators.h
  include/llvm/CodeGen/MachineDominators.h
  include/llvm/IR/Dominators.h
  include/llvm/Support/GenericDomTree.h
  include/llvm/Support/GenericDomTreeConstruction.h
  lib/Analysis/PostDominators.cpp
  lib/CodeGen/MachineDominators.cpp
  lib/IR/Dominators.cpp
  lib/Transforms/Scalar/LoopDistribute.cpp
  lib/Transforms/Scalar/SimpleLoopUnswitch.cpp
  lib/Transforms/Utils/LibCallsShrinkWrap.cpp
  lib/Transforms/Utils/LoopUnroll.cpp
  lib/Transforms/Utils/LoopUnrollPeel.cpp
  lib/Transforms/Vectorize/LoopVectorize.cpp
  unittests/IR/DominatorTreeTest.cpp
  unittests/Transforms/Scalar/LoopPassManagerTest.cpp

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