Import LLVM, at r72732.

1 files changed, 1055 insertions, 0 deletions

diff --git a/include/llvm/Analysis/Dominators.h b/include/llvm/Analysis/Dominators.h
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+++ b/include/llvm/Analysis/Dominators.h
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+//===- llvm/Analysis/Dominators.h - Dominator Info Calculation --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines the following classes:
+//  1. DominatorTree: Represent dominators as an explicit tree structure.
+//  2. DominanceFrontier: Calculate and hold the dominance frontier for a
+//     function.
+//
+//  These data structures are listed in increasing order of complexity.  It
+//  takes longer to calculate the dominator frontier, for example, than the
+//  DominatorTree mapping.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ANALYSIS_DOMINATORS_H
+#define LLVM_ANALYSIS_DOMINATORS_H
+
+#include "llvm/Pass.h"
+#include "llvm/BasicBlock.h"
+#include "llvm/Function.h"
+#include "llvm/Instructions.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/Assembly/Writer.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include <algorithm>
+#include <map>
+#include <set>
+
+namespace llvm {
+
+//===----------------------------------------------------------------------===//
+/// DominatorBase - Base class that other, more interesting dominator analyses
+/// inherit from.
+///
+template <class NodeT>
+class DominatorBase {
+protected:
+  std::vector<NodeT*> Roots;
+  const bool IsPostDominators;
+  inline explicit DominatorBase(bool isPostDom) :
+    Roots(), IsPostDominators(isPostDom) {}
+public:
+
+  /// getRoots -  Return the root blocks of the current CFG.  This may include
+  /// multiple blocks if we are computing post dominators.  For forward
+  /// dominators, this will always be a single block (the entry node).
+  ///
+  inline const std::vector<NodeT*> &getRoots() const { return Roots; }
+
+  /// isPostDominator - Returns true if analysis based of postdoms
+  ///
+  bool isPostDominator() const { return IsPostDominators; }
+};
+
+
+//===----------------------------------------------------------------------===//
+// DomTreeNode - Dominator Tree Node
+template<class NodeT> class DominatorTreeBase;
+struct PostDominatorTree;
+class MachineBasicBlock;
+
+template <class NodeT>
+class DomTreeNodeBase {
+  NodeT *TheBB;
+  DomTreeNodeBase<NodeT> *IDom;
+  std::vector<DomTreeNodeBase<NodeT> *> Children;
+  int DFSNumIn, DFSNumOut;
+
+  template<class N> friend class DominatorTreeBase;
+  friend struct PostDominatorTree;
+public:
+  typedef typename std::vector<DomTreeNodeBase<NodeT> *>::iterator iterator;
+  typedef typename std::vector<DomTreeNodeBase<NodeT> *>::const_iterator
+                   const_iterator;
+  
+  iterator begin()             { return Children.begin(); }
+  iterator end()               { return Children.end(); }
+  const_iterator begin() const { return Children.begin(); }
+  const_iterator end()   const { return Children.end(); }
+  
+  NodeT *getBlock() const { return TheBB; }
+  DomTreeNodeBase<NodeT> *getIDom() const { return IDom; }
+  const std::vector<DomTreeNodeBase<NodeT>*> &getChildren() const {
+    return Children;
+  }
+
+  DomTreeNodeBase(NodeT *BB, DomTreeNodeBase<NodeT> *iDom)
+    : TheBB(BB), IDom(iDom), DFSNumIn(-1), DFSNumOut(-1) { }
+  
+  DomTreeNodeBase<NodeT> *addChild(DomTreeNodeBase<NodeT> *C) {
+    Children.push_back(C);
+    return C;
+  }
+
+  size_t getNumChildren() const {
+    return Children.size();
+  }
+
+  void clearAllChildren() {
+    Children.clear();
+  }
+  
+  bool compare(DomTreeNodeBase<NodeT> *Other) {
+    if (getNumChildren() != Other->getNumChildren())
+      return true;
+
+    SmallPtrSet<NodeT *, 4> OtherChildren;
+    for(iterator I = Other->begin(), E = Other->end(); I != E; ++I) {
+      NodeT *Nd = (*I)->getBlock();
+      OtherChildren.insert(Nd);
+    }
+
+    for(iterator I = begin(), E = end(); I != E; ++I) {
+      NodeT *N = (*I)->getBlock();
+      if (OtherChildren.count(N) == 0)
+        return true;
+    }
+    return false;
+  }
+
+  void setIDom(DomTreeNodeBase<NodeT> *NewIDom) {
+    assert(IDom && "No immediate dominator?");
+    if (IDom != NewIDom) {
+      typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
+                  std::find(IDom->Children.begin(), IDom->Children.end(), this);
+      assert(I != IDom->Children.end() &&
+             "Not in immediate dominator children set!");
+      // I am no longer your child...
+      IDom->Children.erase(I);
+
+      // Switch to new dominator
+      IDom = NewIDom;
+      IDom->Children.push_back(this);
+    }
+  }
+  
+  /// getDFSNumIn/getDFSNumOut - These are an internal implementation detail, do
+  /// not call them.
+  unsigned getDFSNumIn() const { return DFSNumIn; }
+  unsigned getDFSNumOut() const { return DFSNumOut; }
+private:
+  // Return true if this node is dominated by other. Use this only if DFS info
+  // is valid.
+  bool DominatedBy(const DomTreeNodeBase<NodeT> *other) const {
+    return this->DFSNumIn >= other->DFSNumIn &&
+      this->DFSNumOut <= other->DFSNumOut;
+  }
+};
+
+EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<BasicBlock>);
+EXTERN_TEMPLATE_INSTANTIATION(class DomTreeNodeBase<MachineBasicBlock>);
+
+template<class NodeT>
+static std::ostream &operator<<(std::ostream &o,
+                                const DomTreeNodeBase<NodeT> *Node) {
+  if (Node->getBlock())
+    WriteAsOperand(o, Node->getBlock(), false);
+  else
+    o << " <<exit node>>";
+  
+  o << " {" << Node->getDFSNumIn() << "," << Node->getDFSNumOut() << "}";
+  
+  return o << "\n";
+}
+
+template<class NodeT>
+static void PrintDomTree(const DomTreeNodeBase<NodeT> *N, std::ostream &o,
+                         unsigned Lev) {
+  o << std::string(2*Lev, ' ') << "[" << Lev << "] " << N;
+  for (typename DomTreeNodeBase<NodeT>::const_iterator I = N->begin(),
+       E = N->end(); I != E; ++I)
+    PrintDomTree<NodeT>(*I, o, Lev+1);
+}
+
+typedef DomTreeNodeBase<BasicBlock> DomTreeNode;
+
+//===----------------------------------------------------------------------===//
+/// DominatorTree - Calculate the immediate dominator tree for a function.
+///
+
+template<class FuncT, class N>
+void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
+               FuncT& F);
+
+template<class NodeT>
+class DominatorTreeBase : public DominatorBase<NodeT> {
+protected:
+  typedef DenseMap<NodeT*, DomTreeNodeBase<NodeT>*> DomTreeNodeMapType;
+  DomTreeNodeMapType DomTreeNodes;
+  DomTreeNodeBase<NodeT> *RootNode;
+
+  bool DFSInfoValid;
+  unsigned int SlowQueries;
+  // Information record used during immediate dominators computation.
+  struct InfoRec {
+    unsigned DFSNum;
+    unsigned Semi;
+    unsigned Size;
+    NodeT *Label, *Child;
+    unsigned Parent, Ancestor;
+
+    std::vector<NodeT*> Bucket;
+
+    InfoRec() : DFSNum(0), Semi(0), Size(0), Label(0), Child(0), Parent(0),
+                Ancestor(0) {}
+  };
+
+  DenseMap<NodeT*, NodeT*> IDoms;
+
+  // Vertex - Map the DFS number to the BasicBlock*
+  std::vector<NodeT*> Vertex;
+
+  // Info - Collection of information used during the computation of idoms.
+  DenseMap<NodeT*, InfoRec> Info;
+
+  void reset() {
+    for (typename DomTreeNodeMapType::iterator I = this->DomTreeNodes.begin(), 
+           E = DomTreeNodes.end(); I != E; ++I)
+      delete I->second;
+    DomTreeNodes.clear();
+    IDoms.clear();
+    this->Roots.clear();
+    Vertex.clear();
+    RootNode = 0;
+  }
+  
+  // NewBB is split and now it has one successor. Update dominator tree to
+  // reflect this change.
+  template<class N, class GraphT>
+  void Split(DominatorTreeBase<typename GraphT::NodeType>& DT,
+             typename GraphT::NodeType* NewBB) {
+    assert(std::distance(GraphT::child_begin(NewBB), GraphT::child_end(NewBB)) == 1
+           && "NewBB should have a single successor!");
+    typename GraphT::NodeType* NewBBSucc = *GraphT::child_begin(NewBB);
+
+    std::vector<typename GraphT::NodeType*> PredBlocks;
+    for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
+         GraphTraits<Inverse<N> >::child_begin(NewBB),
+         PE = GraphTraits<Inverse<N> >::child_end(NewBB); PI != PE; ++PI)
+      PredBlocks.push_back(*PI);  
+
+    assert(!PredBlocks.empty() && "No predblocks??");
+
+    bool NewBBDominatesNewBBSucc = true;
+    for (typename GraphTraits<Inverse<N> >::ChildIteratorType PI =
+         GraphTraits<Inverse<N> >::child_begin(NewBBSucc),
+         E = GraphTraits<Inverse<N> >::child_end(NewBBSucc); PI != E; ++PI)
+      if (*PI != NewBB && !DT.dominates(NewBBSucc, *PI) &&
+          DT.isReachableFromEntry(*PI)) {
+        NewBBDominatesNewBBSucc = false;
+        break;
+      }
+
+    // Find NewBB's immediate dominator and create new dominator tree node for
+    // NewBB.
+    NodeT *NewBBIDom = 0;
+    unsigned i = 0;
+    for (i = 0; i < PredBlocks.size(); ++i)
+      if (DT.isReachableFromEntry(PredBlocks[i])) {
+        NewBBIDom = PredBlocks[i];
+        break;
+      }
+    assert(i != PredBlocks.size() && "No reachable preds?");
+    for (i = i + 1; i < PredBlocks.size(); ++i) {
+      if (DT.isReachableFromEntry(PredBlocks[i]))
+        NewBBIDom = DT.findNearestCommonDominator(NewBBIDom, PredBlocks[i]);
+    }
+    assert(NewBBIDom && "No immediate dominator found??");
+
+    // Create the new dominator tree node... and set the idom of NewBB.
+    DomTreeNodeBase<NodeT> *NewBBNode = DT.addNewBlock(NewBB, NewBBIDom);
+
+    // If NewBB strictly dominates other blocks, then it is now the immediate
+    // dominator of NewBBSucc.  Update the dominator tree as appropriate.
+    if (NewBBDominatesNewBBSucc) {
+      DomTreeNodeBase<NodeT> *NewBBSuccNode = DT.getNode(NewBBSucc);
+      DT.changeImmediateDominator(NewBBSuccNode, NewBBNode);
+    }
+  }
+
+public:
+  explicit DominatorTreeBase(bool isPostDom)
+    : DominatorBase<NodeT>(isPostDom), DFSInfoValid(false), SlowQueries(0) {}
+  virtual ~DominatorTreeBase() { reset(); }
+
+  // FIXME: Should remove this
+  virtual bool runOnFunction(Function &F) { return false; }
+
+  /// compare - Return false if the other dominator tree base matches this
+  /// dominator tree base. Otherwise return true.
+  bool compare(DominatorTreeBase &Other) const {
+
+    const DomTreeNodeMapType &OtherDomTreeNodes = Other.DomTreeNodes;
+    if (DomTreeNodes.size() != OtherDomTreeNodes.size())
+      return true;
+
+    SmallPtrSet<const NodeT *,4> MyBBs;
+    for (typename DomTreeNodeMapType::const_iterator 
+           I = this->DomTreeNodes.begin(),
+           E = this->DomTreeNodes.end(); I != E; ++I) {
+      NodeT *BB = I->first;
+      typename DomTreeNodeMapType::const_iterator OI = OtherDomTreeNodes.find(BB);
+      if (OI == OtherDomTreeNodes.end())
+        return true;
+
+      DomTreeNodeBase<NodeT>* MyNd = I->second;
+      DomTreeNodeBase<NodeT>* OtherNd = OI->second;
+      
+      if (MyNd->compare(OtherNd))
+        return true;
+    }
+
+    return false;
+  }
+
+  virtual void releaseMemory() { reset(); }
+
+  /// getNode - return the (Post)DominatorTree node for the specified basic
+  /// block.  This is the same as using operator[] on this class.
+  ///
+  inline DomTreeNodeBase<NodeT> *getNode(NodeT *BB) const {
+    typename DomTreeNodeMapType::const_iterator I = DomTreeNodes.find(BB);
+    return I != DomTreeNodes.end() ? I->second : 0;
+  }
+
+  /// getRootNode - This returns the entry node for the CFG of the function.  If
+  /// this tree represents the post-dominance relations for a function, however,
+  /// this root may be a node with the block == NULL.  This is the case when
+  /// there are multiple exit nodes from a particular function.  Consumers of
+  /// post-dominance information must be capable of dealing with this
+  /// possibility.
+  ///
+  DomTreeNodeBase<NodeT> *getRootNode() { return RootNode; }
+  const DomTreeNodeBase<NodeT> *getRootNode() const { return RootNode; }
+
+  /// properlyDominates - Returns true iff this dominates N and this != N.
+  /// Note that this is not a constant time operation!
+  ///
+  bool properlyDominates(const DomTreeNodeBase<NodeT> *A,
+                         DomTreeNodeBase<NodeT> *B) const {
+    if (A == 0 || B == 0) return false;
+    return dominatedBySlowTreeWalk(A, B);
+  }
+
+  inline bool properlyDominates(NodeT *A, NodeT *B) {
+    return properlyDominates(getNode(A), getNode(B));
+  }
+
+  bool dominatedBySlowTreeWalk(const DomTreeNodeBase<NodeT> *A, 
+                               const DomTreeNodeBase<NodeT> *B) const {
+    const DomTreeNodeBase<NodeT> *IDom;
+    if (A == 0 || B == 0) return false;
+    while ((IDom = B->getIDom()) != 0 && IDom != A && IDom != B)
+      B = IDom;   // Walk up the tree
+    return IDom != 0;
+  }
+
+
+  /// isReachableFromEntry - Return true if A is dominated by the entry
+  /// block of the function containing it.
+  bool isReachableFromEntry(NodeT* A) {
+    assert (!this->isPostDominator() 
+            && "This is not implemented for post dominators");
+    return dominates(&A->getParent()->front(), A);
+  }
+  
+  /// dominates - Returns true iff A dominates B.  Note that this is not a
+  /// constant time operation!
+  ///
+  inline bool dominates(const DomTreeNodeBase<NodeT> *A,
+                        DomTreeNodeBase<NodeT> *B) {
+    if (B == A) 
+      return true;  // A node trivially dominates itself.
+
+    if (A == 0 || B == 0)
+      return false;
+
+    if (DFSInfoValid)
+      return B->DominatedBy(A);
+
+    // If we end up with too many slow queries, just update the
+    // DFS numbers on the theory that we are going to keep querying.
+    SlowQueries++;
+    if (SlowQueries > 32) {
+      updateDFSNumbers();
+      return B->DominatedBy(A);
+    }
+
+    return dominatedBySlowTreeWalk(A, B);
+  }
+
+  inline bool dominates(NodeT *A, NodeT *B) {
+    if (A == B) 
+      return true;
+    
+    return dominates(getNode(A), getNode(B));
+  }
+  
+  NodeT *getRoot() const {
+    assert(this->Roots.size() == 1 && "Should always have entry node!");
+    return this->Roots[0];
+  }
+
+  /// findNearestCommonDominator - Find nearest common dominator basic block
+  /// for basic block A and B. If there is no such block then return NULL.
+  NodeT *findNearestCommonDominator(NodeT *A, NodeT *B) {
+
+    assert (!this->isPostDominator() 
+            && "This is not implemented for post dominators");
+    assert (A->getParent() == B->getParent() 
+            && "Two blocks are not in same function");
+
+    // If either A or B is a entry block then it is nearest common dominator.
+    NodeT &Entry  = A->getParent()->front();
+    if (A == &Entry || B == &Entry)
+      return &Entry;
+
+    // If B dominates A then B is nearest common dominator.
+    if (dominates(B, A))
+      return B;
+
+    // If A dominates B then A is nearest common dominator.
+    if (dominates(A, B))
+      return A;
+
+    DomTreeNodeBase<NodeT> *NodeA = getNode(A);
+    DomTreeNodeBase<NodeT> *NodeB = getNode(B);
+
+    // Collect NodeA dominators set.
+    SmallPtrSet<DomTreeNodeBase<NodeT>*, 16> NodeADoms;
+    NodeADoms.insert(NodeA);
+    DomTreeNodeBase<NodeT> *IDomA = NodeA->getIDom();
+    while (IDomA) {
+      NodeADoms.insert(IDomA);
+      IDomA = IDomA->getIDom();
+    }
+
+    // Walk NodeB immediate dominators chain and find common dominator node.
+    DomTreeNodeBase<NodeT> *IDomB = NodeB->getIDom();
+    while(IDomB) {
+      if (NodeADoms.count(IDomB) != 0)
+        return IDomB->getBlock();
+
+      IDomB = IDomB->getIDom();
+    }
+
+    return NULL;
+  }
+
+  //===--------------------------------------------------------------------===//
+  // API to update (Post)DominatorTree information based on modifications to
+  // the CFG...
+
+  /// addNewBlock - Add a new node to the dominator tree information.  This
+  /// creates a new node as a child of DomBB dominator node,linking it into 
+  /// the children list of the immediate dominator.
+  DomTreeNodeBase<NodeT> *addNewBlock(NodeT *BB, NodeT *DomBB) {
+    assert(getNode(BB) == 0 && "Block already in dominator tree!");
+    DomTreeNodeBase<NodeT> *IDomNode = getNode(DomBB);
+    assert(IDomNode && "Not immediate dominator specified for block!");
+    DFSInfoValid = false;
+    return DomTreeNodes[BB] = 
+      IDomNode->addChild(new DomTreeNodeBase<NodeT>(BB, IDomNode));
+  }
+
+  /// changeImmediateDominator - This method is used to update the dominator
+  /// tree information when a node's immediate dominator changes.
+  ///
+  void changeImmediateDominator(DomTreeNodeBase<NodeT> *N,
+                                DomTreeNodeBase<NodeT> *NewIDom) {
+    assert(N && NewIDom && "Cannot change null node pointers!");
+    DFSInfoValid = false;
+    N->setIDom(NewIDom);
+  }
+
+  void changeImmediateDominator(NodeT *BB, NodeT *NewBB) {
+    changeImmediateDominator(getNode(BB), getNode(NewBB));
+  }
+
+  /// eraseNode - Removes a node from  the dominator tree. Block must not
+  /// domiante any other blocks. Removes node from its immediate dominator's
+  /// children list. Deletes dominator node associated with basic block BB.
+  void eraseNode(NodeT *BB) {
+    DomTreeNodeBase<NodeT> *Node = getNode(BB);
+    assert (Node && "Removing node that isn't in dominator tree.");
+    assert (Node->getChildren().empty() && "Node is not a leaf node.");
+
+      // Remove node from immediate dominator's children list.
+    DomTreeNodeBase<NodeT> *IDom = Node->getIDom();
+    if (IDom) {
+      typename std::vector<DomTreeNodeBase<NodeT>*>::iterator I =
+        std::find(IDom->Children.begin(), IDom->Children.end(), Node);
+      assert(I != IDom->Children.end() &&
+             "Not in immediate dominator children set!");
+      // I am no longer your child...
+      IDom->Children.erase(I);
+    }
+
+    DomTreeNodes.erase(BB);
+    delete Node;
+  }
+
+  /// removeNode - Removes a node from the dominator tree.  Block must not
+  /// dominate any other blocks.  Invalidates any node pointing to removed
+  /// block.
+  void removeNode(NodeT *BB) {
+    assert(getNode(BB) && "Removing node that isn't in dominator tree.");
+    DomTreeNodes.erase(BB);
+  }
+  
+  /// splitBlock - BB is split and now it has one successor. Update dominator
+  /// tree to reflect this change.
+  void splitBlock(NodeT* NewBB) {
+    if (this->IsPostDominators)
+      this->Split<Inverse<NodeT*>, GraphTraits<Inverse<NodeT*> > >(*this, NewBB);
+    else
+      this->Split<NodeT*, GraphTraits<NodeT*> >(*this, NewBB);
+  }
+
+  /// print - Convert to human readable form
+  ///
+  virtual void print(std::ostream &o, const Module* ) const {
+    o << "=============================--------------------------------\n";
+    if (this->isPostDominator())
+      o << "Inorder PostDominator Tree: ";
+    else
+      o << "Inorder Dominator Tree: ";
+    if (this->DFSInfoValid)
+      o << "DFSNumbers invalid: " << SlowQueries << " slow queries.";
+    o << "\n";
+
+    PrintDomTree<NodeT>(getRootNode(), o, 1);
+  }
+  
+  void print(std::ostream *OS, const Module* M = 0) const {
+    if (OS) print(*OS, M);
+  }
+  
+  virtual void dump() {
+    print(llvm::cerr);
+  }
+  
+protected:
+  template<class GraphT>
+  friend void Compress(DominatorTreeBase<typename GraphT::NodeType>& DT,
+                       typename GraphT::NodeType* VIn);
+
+  template<class GraphT>
+  friend typename GraphT::NodeType* Eval(
+                               DominatorTreeBase<typename GraphT::NodeType>& DT,
+                                         typename GraphT::NodeType* V);
+
+  template<class GraphT>
+  friend void Link(DominatorTreeBase<typename GraphT::NodeType>& DT,
+                   unsigned DFSNumV, typename GraphT::NodeType* W,
+         typename DominatorTreeBase<typename GraphT::NodeType>::InfoRec &WInfo);
+  
+  template<class GraphT>
+  friend unsigned DFSPass(DominatorTreeBase<typename GraphT::NodeType>& DT,
+                          typename GraphT::NodeType* V,
+                          unsigned N);
+  
+  template<class FuncT, class N>
+  friend void Calculate(DominatorTreeBase<typename GraphTraits<N>::NodeType>& DT,
+                        FuncT& F);
+  
+  /// updateDFSNumbers - Assign In and Out numbers to the nodes while walking
+  /// dominator tree in dfs order.
+  void updateDFSNumbers() {
+    unsigned DFSNum = 0;
+
+    SmallVector<std::pair<DomTreeNodeBase<NodeT>*,
+                typename DomTreeNodeBase<NodeT>::iterator>, 32> WorkStack;
+
+    for (unsigned i = 0, e = (unsigned)this->Roots.size(); i != e; ++i) {
+      DomTreeNodeBase<NodeT> *ThisRoot = getNode(this->Roots[i]);
+      WorkStack.push_back(std::make_pair(ThisRoot, ThisRoot->begin()));
+      ThisRoot->DFSNumIn = DFSNum++;
+
+      while (!WorkStack.empty()) {
+        DomTreeNodeBase<NodeT> *Node = WorkStack.back().first;
+        typename DomTreeNodeBase<NodeT>::iterator ChildIt =
+                                                        WorkStack.back().second;
+
+        // If we visited all of the children of this node, "recurse" back up the
+        // stack setting the DFOutNum.
+        if (ChildIt == Node->end()) {
+          Node->DFSNumOut = DFSNum++;
+          WorkStack.pop_back();
+        } else {
+          // Otherwise, recursively visit this child.
+          DomTreeNodeBase<NodeT> *Child = *ChildIt;
+          ++WorkStack.back().second;
+          
+          WorkStack.push_back(std::make_pair(Child, Child->begin()));
+          Child->DFSNumIn = DFSNum++;
+        }
+      }
+    }
+    
+    SlowQueries = 0;
+    DFSInfoValid = true;
+  }
+  
+  DomTreeNodeBase<NodeT> *getNodeForBlock(NodeT *BB) {
+    if (DomTreeNodeBase<NodeT> *BBNode = this->DomTreeNodes[BB])
+      return BBNode;
+
+    // Haven't calculated this node yet?  Get or calculate the node for the
+    // immediate dominator.
+    NodeT *IDom = getIDom(BB);
+
+    assert(IDom || this->DomTreeNodes[NULL]);
+    DomTreeNodeBase<NodeT> *IDomNode = getNodeForBlock(IDom);
+
+    // Add a new tree node for this BasicBlock, and link it as a child of
+    // IDomNode
+    DomTreeNodeBase<NodeT> *C = new DomTreeNodeBase<NodeT>(BB, IDomNode);
+    return this->DomTreeNodes[BB] = IDomNode->addChild(C);
+  }
+  
+  inline NodeT *getIDom(NodeT *BB) const {
+    typename DenseMap<NodeT*, NodeT*>::const_iterator I = IDoms.find(BB);
+    return I != IDoms.end() ? I->second : 0;
+  }
+  
+  inline void addRoot(NodeT* BB) {
+    this->Roots.push_back(BB);
+  }
+  
+public:
+  /// recalculate - compute a dominator tree for the given function
+  template<class FT>
+  void recalculate(FT& F) {
+    if (!this->IsPostDominators) {
+      reset();
+      
+      // Initialize roots
+      this->Roots.push_back(&F.front());
+      this->IDoms[&F.front()] = 0;
+      this->DomTreeNodes[&F.front()] = 0;
+      this->Vertex.push_back(0);
+      
+      Calculate<FT, NodeT*>(*this, F);
+      
+      updateDFSNumbers();
+    } else {
+      reset();     // Reset from the last time we were run...
+
+      // Initialize the roots list
+      for (typename FT::iterator I = F.begin(), E = F.end(); I != E; ++I) {
+        if (std::distance(GraphTraits<FT*>::child_begin(I),
+                          GraphTraits<FT*>::child_end(I)) == 0)
+          addRoot(I);
+
+        // Prepopulate maps so that we don't get iterator invalidation issues later.
+        this->IDoms[I] = 0;
+        this->DomTreeNodes[I] = 0;
+      }
+
+      this->Vertex.push_back(0);
+      
+      Calculate<FT, Inverse<NodeT*> >(*this, F);
+    }
+  }
+};
+
+EXTERN_TEMPLATE_INSTANTIATION(class DominatorTreeBase<BasicBlock>);
+
+//===-------------------------------------
+/// DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to
+/// compute a normal dominator tree.
+///
+class DominatorTree : public FunctionPass {
+public:
+  static char ID; // Pass ID, replacement for typeid
+  DominatorTreeBase<BasicBlock>* DT;
+  
+  DominatorTree() : FunctionPass(&ID) {
+    DT = new DominatorTreeBase<BasicBlock>(false);
+  }
+  
+  ~DominatorTree() {
+    DT->releaseMemory();
+    delete DT;
+  }
+  
+  DominatorTreeBase<BasicBlock>& getBase() { return *DT; }
+  
+  /// getRoots -  Return the root blocks of the current CFG.  This may include
+  /// multiple blocks if we are computing post dominators.  For forward
+  /// dominators, this will always be a single block (the entry node).
+  ///
+  inline const std::vector<BasicBlock*> &getRoots() const {
+    return DT->getRoots();
+  }
+  
+  inline BasicBlock *getRoot() const {
+    return DT->getRoot();
+  }
+  
+  inline DomTreeNode *getRootNode() const {
+    return DT->getRootNode();
+  }
+
+  /// compare - Return false if the other dominator tree matches this
+  /// dominator tree. Otherwise return true.
+  inline bool compare(DominatorTree &Other) const {
+    DomTreeNode *R = getRootNode();
+    DomTreeNode *OtherR = Other.getRootNode();
+    
+    if (!R || !OtherR || R->getBlock() != OtherR->getBlock())
+      return true;
+    
+    if (DT->compare(Other.getBase()))
+      return true;
+
+    return false;
+  }
+
+  virtual bool runOnFunction(Function &F);
+  
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    AU.setPreservesAll();
+  }
+  
+  inline bool dominates(DomTreeNode* A, DomTreeNode* B) const {
+    return DT->dominates(A, B);
+  }
+  
+  inline bool dominates(BasicBlock* A, BasicBlock* B) const {
+    return DT->dominates(A, B);
+  }
+  
+  // dominates - Return true if A dominates B. This performs the
+  // special checks necessary if A and B are in the same basic block.
+  bool dominates(Instruction *A, Instruction *B) const {
+    BasicBlock *BBA = A->getParent(), *BBB = B->getParent();
+    if (BBA != BBB) return DT->dominates(BBA, BBB);
+
+    // It is not possible to determine dominance between two PHI nodes 
+    // based on their ordering.
+    if (isa<PHINode>(A) && isa<PHINode>(B)) 
+      return false;
+
+    // Loop through the basic block until we find A or B.
+    BasicBlock::iterator I = BBA->begin();
+    for (; &*I != A && &*I != B; ++I) /*empty*/;
+
+    //if(!DT.IsPostDominators) {
+      // A dominates B if it is found first in the basic block.
+      return &*I == A;
+    //} else {
+    //  // A post-dominates B if B is found first in the basic block.
+    //  return &*I == B;
+    //}
+  }
+  
+  inline bool properlyDominates(const DomTreeNode* A, DomTreeNode* B) const {
+    return DT->properlyDominates(A, B);
+  }
+  
+  inline bool properlyDominates(BasicBlock* A, BasicBlock* B) const {
+    return DT->properlyDominates(A, B);
+  }
+  
+  /// findNearestCommonDominator - Find nearest common dominator basic block
+  /// for basic block A and B. If there is no such block then return NULL.
+  inline BasicBlock *findNearestCommonDominator(BasicBlock *A, BasicBlock *B) {
+    return DT->findNearestCommonDominator(A, B);
+  }
+  
+  inline DomTreeNode *operator[](BasicBlock *BB) const {
+    return DT->getNode(BB);
+  }
+  
+  /// getNode - return the (Post)DominatorTree node for the specified basic
+  /// block.  This is the same as using operator[] on this class.
+  ///
+  inline DomTreeNode *getNode(BasicBlock *BB) const {
+    return DT->getNode(BB);
+  }
+  
+  /// addNewBlock - Add a new node to the dominator tree information.  This
+  /// creates a new node as a child of DomBB dominator node,linking it into 
+  /// the children list of the immediate dominator.
+  inline DomTreeNode *addNewBlock(BasicBlock *BB, BasicBlock *DomBB) {
+    return DT->addNewBlock(BB, DomBB);
+  }
+  
+  /// changeImmediateDominator - This method is used to update the dominator
+  /// tree information when a node's immediate dominator changes.
+  ///
+  inline void changeImmediateDominator(BasicBlock *N, BasicBlock* NewIDom) {
+    DT->changeImmediateDominator(N, NewIDom);
+  }
+  
+  inline void changeImmediateDominator(DomTreeNode *N, DomTreeNode* NewIDom) {
+    DT->changeImmediateDominator(N, NewIDom);
+  }
+  
+  /// eraseNode - Removes a node from  the dominator tree. Block must not
+  /// domiante any other blocks. Removes node from its immediate dominator's
+  /// children list. Deletes dominator node associated with basic block BB.
+  inline void eraseNode(BasicBlock *BB) {
+    DT->eraseNode(BB);
+  }
+  
+  /// splitBlock - BB is split and now it has one successor. Update dominator
+  /// tree to reflect this change.
+  inline void splitBlock(BasicBlock* NewBB) {
+    DT->splitBlock(NewBB);
+  }
+  
+  bool isReachableFromEntry(BasicBlock* A) {
+    return DT->isReachableFromEntry(A);
+  }
+  
+  
+  virtual void releaseMemory() { 
+    DT->releaseMemory();
+  }
+  
+  virtual void print(std::ostream &OS, const Module* M= 0) const {
+    DT->print(OS, M);
+  }
+};
+
+//===-------------------------------------
+/// DominatorTree GraphTraits specialization so the DominatorTree can be
+/// iterable by generic graph iterators.
+///
+template <> struct GraphTraits<DomTreeNode *> {
+  typedef DomTreeNode NodeType;
+  typedef NodeType::iterator  ChildIteratorType;
+  
+  static NodeType *getEntryNode(NodeType *N) {
+    return N;
+  }
+  static inline ChildIteratorType child_begin(NodeType* N) {
+    return N->begin();
+  }
+  static inline ChildIteratorType child_end(NodeType* N) {
+    return N->end();
+  }
+};
+
+template <> struct GraphTraits<DominatorTree*>
+  : public GraphTraits<DomTreeNode *> {
+  static NodeType *getEntryNode(DominatorTree *DT) {
+    return DT->getRootNode();
+  }
+};
+
+
+//===----------------------------------------------------------------------===//
+/// DominanceFrontierBase - Common base class for computing forward and inverse
+/// dominance frontiers for a function.
+///
+class DominanceFrontierBase : public FunctionPass {
+public:
+  typedef std::set<BasicBlock*>             DomSetType;    // Dom set for a bb
+  typedef std::map<BasicBlock*, DomSetType> DomSetMapType; // Dom set map
+protected:
+  DomSetMapType Frontiers;
+  std::vector<BasicBlock*> Roots;
+  const bool IsPostDominators;
+  
+public:
+  DominanceFrontierBase(void *ID, bool isPostDom) 
+    : FunctionPass(ID), IsPostDominators(isPostDom) {}
+
+  /// getRoots -  Return the root blocks of the current CFG.  This may include
+  /// multiple blocks if we are computing post dominators.  For forward
+  /// dominators, this will always be a single block (the entry node).
+  ///
+  inline const std::vector<BasicBlock*> &getRoots() const { return Roots; }
+  
+  /// isPostDominator - Returns true if analysis based of postdoms
+  ///
+  bool isPostDominator() const { return IsPostDominators; }
+
+  virtual void releaseMemory() { Frontiers.clear(); }
+
+  // Accessor interface:
+  typedef DomSetMapType::iterator iterator;
+  typedef DomSetMapType::const_iterator const_iterator;
+  iterator       begin()       { return Frontiers.begin(); }
+  const_iterator begin() const { return Frontiers.begin(); }
+  iterator       end()         { return Frontiers.end(); }
+  const_iterator end()   const { return Frontiers.end(); }
+  iterator       find(BasicBlock *B)       { return Frontiers.find(B); }
+  const_iterator find(BasicBlock *B) const { return Frontiers.find(B); }
+
+  void addBasicBlock(BasicBlock *BB, const DomSetType &frontier) {
+    assert(find(BB) == end() && "Block already in DominanceFrontier!");
+    Frontiers.insert(std::make_pair(BB, frontier));
+  }
+
+  /// removeBlock - Remove basic block BB's frontier.
+  void removeBlock(BasicBlock *BB) {
+    assert(find(BB) != end() && "Block is not in DominanceFrontier!");
+    for (iterator I = begin(), E = end(); I != E; ++I)
+      I->second.erase(BB);
+    Frontiers.erase(BB);
+  }
+
+  void addToFrontier(iterator I, BasicBlock *Node) {
+    assert(I != end() && "BB is not in DominanceFrontier!");
+    I->second.insert(Node);
+  }
+
+  void removeFromFrontier(iterator I, BasicBlock *Node) {
+    assert(I != end() && "BB is not in DominanceFrontier!");
+    assert(I->second.count(Node) && "Node is not in DominanceFrontier of BB");
+    I->second.erase(Node);
+  }
+
+  /// compareDomSet - Return false if two domsets match. Otherwise
+  /// return true;
+  bool compareDomSet(DomSetType &DS1, const DomSetType &DS2) const {
+    std::set<BasicBlock *> tmpSet;
+    for (DomSetType::const_iterator I = DS2.begin(),
+           E = DS2.end(); I != E; ++I) 
+      tmpSet.insert(*I);
+
+    for (DomSetType::const_iterator I = DS1.begin(),
+           E = DS1.end(); I != E; ) {
+      BasicBlock *Node = *I++;
+
+      if (tmpSet.erase(Node) == 0)
+        // Node is in DS1 but not in DS2.
+        return true;
+    }
+
+    if(!tmpSet.empty())
+      // There are nodes that are in DS2 but not in DS1.
+      return true;
+
+    // DS1 and DS2 matches.
+    return false;
+  }
+
+  /// compare - Return true if the other dominance frontier base matches
+  /// this dominance frontier base. Otherwise return false.
+  bool compare(DominanceFrontierBase &Other) const {
+    DomSetMapType tmpFrontiers;
+    for (DomSetMapType::const_iterator I = Other.begin(),
+           E = Other.end(); I != E; ++I) 
+      tmpFrontiers.insert(std::make_pair(I->first, I->second));
+
+    for (DomSetMapType::iterator I = tmpFrontiers.begin(),
+           E = tmpFrontiers.end(); I != E; ) {
+      BasicBlock *Node = I->first;
+      const_iterator DFI = find(Node);
+      if (DFI == end()) 
+        return true;
+
+      if (compareDomSet(I->second, DFI->second))
+        return true;
+
+      ++I;
+      tmpFrontiers.erase(Node);
+    }
+
+    if (!tmpFrontiers.empty())
+      return true;
+
+    return false;
+  }
+
+  /// print - Convert to human readable form
+  ///
+  virtual void print(std::ostream &OS, const Module* = 0) const;
+  void print(std::ostream *OS, const Module* M = 0) const {
+    if (OS) print(*OS, M);
+  }
+  virtual void dump();
+};
+
+
+//===-------------------------------------
+/// DominanceFrontier Class - Concrete subclass of DominanceFrontierBase that is
+/// used to compute a forward dominator frontiers.
+///
+class DominanceFrontier : public DominanceFrontierBase {
+public:
+  static char ID; // Pass ID, replacement for typeid
+  DominanceFrontier() : 
+    DominanceFrontierBase(&ID, false) {}
+
+  BasicBlock *getRoot() const {
+    assert(Roots.size() == 1 && "Should always have entry node!");
+    return Roots[0];
+  }
+
+  virtual bool runOnFunction(Function &) {
+    Frontiers.clear();
+    DominatorTree &DT = getAnalysis<DominatorTree>();
+    Roots = DT.getRoots();
+    assert(Roots.size() == 1 && "Only one entry block for forward domfronts!");
+    calculate(DT, DT[Roots[0]]);
+    return false;
+  }
+
+  virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+    AU.setPreservesAll();
+    AU.addRequired<DominatorTree>();
+  }
+
+  /// splitBlock - BB is split and now it has one successor. Update dominance
+  /// frontier to reflect this change.
+  void splitBlock(BasicBlock *BB);
+
+  /// BasicBlock BB's new dominator is NewBB. Update BB's dominance frontier
+  /// to reflect this change.
+  void changeImmediateDominator(BasicBlock *BB, BasicBlock *NewBB,
+                                DominatorTree *DT) {
+    // NewBB is now  dominating BB. Which means BB's dominance
+    // frontier is now part of NewBB's dominance frontier. However, BB
+    // itself is not member of NewBB's dominance frontier.
+    DominanceFrontier::iterator NewDFI = find(NewBB);
+    DominanceFrontier::iterator DFI = find(BB);
+    // If BB was an entry block then its frontier is empty.
+    if (DFI == end())
+      return;
+    DominanceFrontier::DomSetType BBSet = DFI->second;
+    for (DominanceFrontier::DomSetType::iterator BBSetI = BBSet.begin(),
+           BBSetE = BBSet.end(); BBSetI != BBSetE; ++BBSetI) {
+      BasicBlock *DFMember = *BBSetI;
+      // Insert only if NewBB dominates DFMember.
+      if (!DT->dominates(NewBB, DFMember))
+        NewDFI->second.insert(DFMember);
+    }
+    NewDFI->second.erase(BB);
+  }
+
+  const DomSetType &calculate(const DominatorTree &DT,
+                              const DomTreeNode *Node);
+};
+
+
+} // End llvm namespace
+
+#endif