X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTransforms%2FScalar%2FPredicateSimplifier.cpp;h=b8ac1828db8c5ebc2a6bf72387195b50b51eca65;hb=ca74940fee04662a61cee290a1b04ef2f2b52c09;hp=aecd6957bd597f00ecd83f55a79a248b9a791187;hpb=6a08f918b649eb6246da5d254dbbc22c1e5816c6;p=oota-llvm.git

diff --git a/lib/Transforms/Scalar/PredicateSimplifier.cpp b/lib/Transforms/Scalar/PredicateSimplifier.cpp
index aecd6957bd5..b8ac1828db8 100644
--- a/lib/Transforms/Scalar/PredicateSimplifier.cpp
+++ b/lib/Transforms/Scalar/PredicateSimplifier.cpp
@@ -2,8 +2,8 @@
 //
 //                     The LLVM Compiler Infrastructure
 //
-// This file was developed by Nick Lewycky and is distributed under the
-// University of Illinois Open Source License. See LICENSE.TXT for details.
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//
 //
@@ -22,16 +22,16 @@
 //
 //===----------------------------------------------------------------------===//
 //
-// This pass focusses on four properties; equals, not equals, less-than
-// and less-than-or-equals-to. The greater-than forms are also held just
-// to allow walking from a lesser node to a greater one. These properties
+// The InequalityGraph focusses on four properties; equals, not equals,
+// less-than and less-than-or-equals-to. The greater-than forms are also held
+// just to allow walking from a lesser node to a greater one. These properties
 // are stored in a lattice; LE can become LT or EQ, NE can become LT or GT.
 //
 // These relationships define a graph between values of the same type. Each
 // Value is stored in a map table that retrieves the associated Node. This
-// is how EQ relationships are stored; the map contains pointers to the
-// same node. The node contains a most canonical Value* form and the list of
-// known relationships.
+// is how EQ relationships are stored; the map contains pointers from equal
+// Value to the same node. The node contains a most canonical Value* form
+// and the list of known relationships with other nodes.
 //
 // If two nodes are known to be inequal, then they will contain pointers to
 // each other with an "NE" relationship. If node getNode(%x) is less than
@@ -52,9 +52,9 @@
 // responsible for analyzing the variable and seeing what new inferences
 // can be made from each property. For example:
 //
-//   %P = setne int* %ptr, null
-//   %a = and bool %P, %Q
-//   br bool %a label %cond_true, label %cond_false
+//   %P = icmp ne i32* %ptr, null
+//   %a = and i1 %P, %Q
+//   br i1 %a label %cond_true, label %cond_false
 //
 // For the true branch, the VRPSolver will start with %a EQ true and look at
 // the definition of %a and find that it can infer that %P and %Q are both
@@ -67,6 +67,17 @@
 // that the dividend is not equal to zero.
 //
 //===----------------------------------------------------------------------===//
+//
+// The ValueRanges class stores the known integer bounds of a Value. When we
+// encounter i8 %a u< %b, the ValueRanges stores that %a = [1, 255] and
+// %b = [0, 254].
+//
+// It never stores an empty range, because that means that the code is
+// unreachable. It never stores a single-element range since that's an equality
+// relationship and better stored in the InequalityGraph, nor an empty range
+// since that is better stored in UnreachableBlocks.
+//
+//===----------------------------------------------------------------------===//
 
 #define DEBUG_TYPE "predsimplify"
 #include "llvm/Transforms/Scalar.h"
@@ -76,27 +87,221 @@
 #include "llvm/Pass.h"
 #include "llvm/ADT/DepthFirstIterator.h"
 #include "llvm/ADT/SetOperations.h"
-#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/Analysis/Dominators.h"
-#include "llvm/Analysis/ET-Forest.h"
+#include "llvm/Assembly/Writer.h"
 #include "llvm/Support/CFG.h"
-#include "llvm/Support/Compiler.h"
+#include "llvm/Support/ConstantRange.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/InstVisitor.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetData.h"
 #include "llvm/Transforms/Utils/Local.h"
 #include <algorithm>
 #include <deque>
-#include <sstream>
+#include <stack>
 using namespace llvm;
 
 STATISTIC(NumVarsReplaced, "Number of argument substitutions");
 STATISTIC(NumInstruction , "Number of instructions removed");
 STATISTIC(NumSimple      , "Number of simple replacements");
 STATISTIC(NumBlocks      , "Number of blocks marked unreachable");
+STATISTIC(NumSnuggle     , "Number of comparisons snuggled");
+
+static const ConstantRange empty(1, false);
 
 namespace {
+  class DomTreeDFS {
+  public:
+    class Node {
+      friend class DomTreeDFS;
+    public:
+      typedef std::vector<Node *>::iterator       iterator;
+      typedef std::vector<Node *>::const_iterator const_iterator;
+
+      unsigned getDFSNumIn()  const { return DFSin;  }
+      unsigned getDFSNumOut() const { return DFSout; }
+
+      BasicBlock *getBlock() const { return BB; }
+
+      iterator begin() { return Children.begin(); }
+      iterator end()   { return Children.end();   }
+
+      const_iterator begin() const { return Children.begin(); }
+      const_iterator end()   const { return Children.end();   }
+
+      bool dominates(const Node *N) const {
+        return DFSin <= N->DFSin && DFSout >= N->DFSout;
+      }
+
+      bool DominatedBy(const Node *N) const {
+        return N->dominates(this);
+      }
+
+      /// Sorts by the number of descendants. With this, you can iterate
+      /// through a sorted list and the first matching entry is the most
+      /// specific match for your basic block. The order provided is stable;
+      /// DomTreeDFS::Nodes with the same number of descendants are sorted by
+      /// DFS in number.
+      bool operator<(const Node &N) const {
+        unsigned   spread =   DFSout -   DFSin;
+        unsigned N_spread = N.DFSout - N.DFSin;
+        if (spread == N_spread) return DFSin < N.DFSin;
+        return spread < N_spread;
+      }
+      bool operator>(const Node &N) const { return N < *this; }
+
+    private:
+      unsigned DFSin, DFSout;
+      BasicBlock *BB;
+
+      std::vector<Node *> Children;
+    };
+
+    // XXX: this may be slow. Instead of using "new" for each node, consider
+    // putting them in a vector to keep them contiguous.
+    explicit DomTreeDFS(DominatorTree *DT) {
+      std::stack<std::pair<Node *, DomTreeNode *> > S;
+
+      Entry = new Node;
+      Entry->BB = DT->getRootNode()->getBlock();
+      S.push(std::make_pair(Entry, DT->getRootNode()));
+
+      NodeMap[Entry->BB] = Entry;
+
+      while (!S.empty()) {
+        std::pair<Node *, DomTreeNode *> &Pair = S.top();
+        Node *N = Pair.first;
+        DomTreeNode *DTNode = Pair.second;
+        S.pop();
+
+        for (DomTreeNode::iterator I = DTNode->begin(), E = DTNode->end();
+             I != E; ++I) {
+          Node *NewNode = new Node;
+          NewNode->BB = (*I)->getBlock();
+          N->Children.push_back(NewNode);
+          S.push(std::make_pair(NewNode, *I));
+
+          NodeMap[NewNode->BB] = NewNode;
+        }
+      }
+
+      renumber();
+
+#ifndef NDEBUG
+      DEBUG(dump());
+#endif
+    }
+
+#ifndef NDEBUG
+    virtual
+#endif
+    ~DomTreeDFS() {
+      std::stack<Node *> S;
+
+      S.push(Entry);
+      while (!S.empty()) {
+        Node *N = S.top(); S.pop();
+
+        for (Node::iterator I = N->begin(), E = N->end(); I != E; ++I)
+          S.push(*I);
+
+        delete N;
+      }
+    }
+
+    /// getRootNode - This returns the entry node for the CFG of the function.
+    Node *getRootNode() const { return Entry; }
+
+    /// getNodeForBlock - return the node for the specified basic block.
+    Node *getNodeForBlock(BasicBlock *BB) const {
+      if (!NodeMap.count(BB)) return 0;
+      return const_cast<DomTreeDFS*>(this)->NodeMap[BB];
+    }
+
+    /// dominates - returns true if the basic block for I1 dominates that of
+    /// the basic block for I2. If the instructions belong to the same basic
+    /// block, the instruction first instruction sequentially in the block is
+    /// considered dominating.
+    bool dominates(Instruction *I1, Instruction *I2) {
+      BasicBlock *BB1 = I1->getParent(),
+                 *BB2 = I2->getParent();
+      if (BB1 == BB2) {
+        if (isa<TerminatorInst>(I1)) return false;
+        if (isa<TerminatorInst>(I2)) return true;
+        if ( isa<PHINode>(I1) && !isa<PHINode>(I2)) return true;
+        if (!isa<PHINode>(I1) &&  isa<PHINode>(I2)) return false;
+
+        for (BasicBlock::const_iterator I = BB2->begin(), E = BB2->end();
+             I != E; ++I) {
+          if (&*I == I1) return true;
+          else if (&*I == I2) return false;
+        }
+        assert(!"Instructions not found in parent BasicBlock?");
+      } else {
+        Node *Node1 = getNodeForBlock(BB1),
+             *Node2 = getNodeForBlock(BB2);
+        return Node1 && Node2 && Node1->dominates(Node2);
+      }
+      return false; // Not reached
+    }
+
+  private:
+    /// renumber - calculates the depth first search numberings and applies
+    /// them onto the nodes.
+    void renumber() {
+      std::stack<std::pair<Node *, Node::iterator> > S;
+      unsigned n = 0;
+
+      Entry->DFSin = ++n;
+      S.push(std::make_pair(Entry, Entry->begin()));
+
+      while (!S.empty()) {
+        std::pair<Node *, Node::iterator> &Pair = S.top();
+        Node *N = Pair.first;
+        Node::iterator &I = Pair.second;
+
+        if (I == N->end()) {
+          N->DFSout = ++n;
+          S.pop();
+        } else {
+          Node *Next = *I++;
+          Next->DFSin = ++n;
+          S.push(std::make_pair(Next, Next->begin()));
+        }
+      }
+    }
+
+#ifndef NDEBUG
+    virtual void dump() const {
+      dump(errs());
+    }
+
+    void dump(raw_ostream &os) const {
+      os << "Predicate simplifier DomTreeDFS: \n";
+      dump(Entry, 0, os);
+      os << "\n\n";
+    }
+
+    void dump(Node *N, int depth, raw_ostream &os) const {
+      ++depth;
+      for (int i = 0; i < depth; ++i) { os << " "; }
+      os << "[" << depth << "] ";
+
+      os << N->getBlock()->getNameStr() << " (" << N->getDFSNumIn()
+         << ", " << N->getDFSNumOut() << ")\n";
+
+      for (Node::iterator I = N->begin(), E = N->end(); I != E; ++I)
+        dump(*I, depth, os);
+    }
+#endif
+
+    Node *Entry;
+    std::map<BasicBlock *, Node *> NodeMap;
+  };
+
   // SLT SGT ULT UGT EQ
   //   0   1   0   1  0 -- GT                  10
   //   0   1   0   1  1 -- GE                  11
@@ -138,22 +343,27 @@ namespace {
     UGE = UGT | EQ_BIT
   };
 
+#ifndef NDEBUG
+  /// validPredicate - determines whether a given value is actually a lattice
+  /// value. Only used in assertions or debugging.
   static bool validPredicate(LatticeVal LV) {
     switch (LV) {
-    case GT: case GE: case LT: case LE: case NE:
-    case SGTULT: case SGT: case SGEULE:
-    case SLTUGT: case SLT: case SLEUGE:
-    case ULT: case UGT:
-    case SLE: case SGE: case ULE: case UGE:
-      return true;
-    default:
-      return false;
+      case GT: case GE: case LT: case LE: case NE:
+      case SGTULT: case SGT: case SGEULE:
+      case SLTUGT: case SLT: case SLEUGE:
+      case ULT: case UGT:
+      case SLE: case SGE: case ULE: case UGE:
+        return true;
+      default:
+        return false;
     }
   }
+#endif
 
   /// reversePredicate - reverse the direction of the inequality
   static LatticeVal reversePredicate(LatticeVal LV) {
     unsigned reverse = LV ^ (SLT_BIT|SGT_BIT|ULT_BIT|UGT_BIT); //preserve EQ_BIT
+
     if ((reverse & (SLT_BIT|SGT_BIT)) == 0)
       reverse |= (SLT_BIT|SGT_BIT);
 
@@ -165,6 +375,215 @@ namespace {
     return Rev;
   }
 
+  /// ValueNumbering stores the scope-specific value numbers for a given Value.
+  class ValueNumbering {
+
+    /// VNPair is a tuple of {Value, index number, DomTreeDFS::Node}. It
+    /// includes the comparison operators necessary to allow you to store it
+    /// in a sorted vector.
+    class VNPair {
+    public:
+      Value *V;
+      unsigned index;
+      DomTreeDFS::Node *Subtree;
+
+      VNPair(Value *V, unsigned index, DomTreeDFS::Node *Subtree)
+        : V(V), index(index), Subtree(Subtree) {}
+
+      bool operator==(const VNPair &RHS) const {
+        return V == RHS.V && Subtree == RHS.Subtree;
+      }
+
+      bool operator<(const VNPair &RHS) const {
+        if (V != RHS.V) return V < RHS.V;
+        return *Subtree < *RHS.Subtree;
+      }
+
+      bool operator<(Value *RHS) const {
+        return V < RHS;
+      }
+
+      bool operator>(Value *RHS) const {
+        return V > RHS;
+      }
+
+      friend bool operator<(Value *RHS, const VNPair &pair) {
+        return pair.operator>(RHS);
+      }
+    };
+
+    typedef std::vector<VNPair> VNMapType;
+    VNMapType VNMap;
+
+    /// The canonical choice for value number at index.
+    std::vector<Value *> Values;
+
+    DomTreeDFS *DTDFS;
+
+  public:
+#ifndef NDEBUG
+    virtual ~ValueNumbering() {}
+    virtual void dump() {
+      print(errs());
+    }
+
+    void print(raw_ostream &os) {
+      for (unsigned i = 1; i <= Values.size(); ++i) {
+        os << i << " = ";
+        WriteAsOperand(os, Values[i-1]);
+        os << " {";
+        for (unsigned j = 0; j < VNMap.size(); ++j) {
+          if (VNMap[j].index == i) {
+            WriteAsOperand(os, VNMap[j].V);
+            os << " (" << VNMap[j].Subtree->getDFSNumIn() << ")  ";
+          }
+        }
+        os << "}\n";
+      }
+    }
+#endif
+
+    /// compare - returns true if V1 is a better canonical value than V2.
+    bool compare(Value *V1, Value *V2) const {
+      if (isa<Constant>(V1))
+        return !isa<Constant>(V2);
+      else if (isa<Constant>(V2))
+        return false;
+      else if (isa<Argument>(V1))
+        return !isa<Argument>(V2);
+      else if (isa<Argument>(V2))
+        return false;
+
+      Instruction *I1 = dyn_cast<Instruction>(V1);
+      Instruction *I2 = dyn_cast<Instruction>(V2);
+
+      if (!I1 || !I2)
+        return V1->getNumUses() < V2->getNumUses();
+
+      return DTDFS->dominates(I1, I2);
+    }
+
+    ValueNumbering(DomTreeDFS *DTDFS) : DTDFS(DTDFS) {}
+
+    /// valueNumber - finds the value number for V under the Subtree. If
+    /// there is no value number, returns zero.
+    unsigned valueNumber(Value *V, DomTreeDFS::Node *Subtree) {
+      if (!(isa<Constant>(V) || isa<Argument>(V) || isa<Instruction>(V)) || 
+          V->getType() == Type::getVoidTy(V->getContext())) return 0;
+
+      VNMapType::iterator E = VNMap.end();
+      VNPair pair(V, 0, Subtree);
+      VNMapType::iterator I = std::lower_bound(VNMap.begin(), E, pair);
+      while (I != E && I->V == V) {
+        if (I->Subtree->dominates(Subtree))
+          return I->index;
+        ++I;
+      }
+      return 0;
+    }
+
+    /// getOrInsertVN - always returns a value number, creating it if necessary.
+    unsigned getOrInsertVN(Value *V, DomTreeDFS::Node *Subtree) {
+      if (unsigned n = valueNumber(V, Subtree))
+        return n;
+      else
+        return newVN(V);
+    }
+
+    /// newVN - creates a new value number. Value V must not already have a
+    /// value number assigned.
+    unsigned newVN(Value *V) {
+      assert((isa<Constant>(V) || isa<Argument>(V) || isa<Instruction>(V)) &&
+             "Bad Value for value numbering.");
+      assert(V->getType() != Type::getVoidTy(V->getContext()) &&
+             "Won't value number a void value");
+
+      Values.push_back(V);
+
+      VNPair pair = VNPair(V, Values.size(), DTDFS->getRootNode());
+      VNMapType::iterator I = std::lower_bound(VNMap.begin(), VNMap.end(), pair);
+      assert((I == VNMap.end() || value(I->index) != V) &&
+             "Attempt to create a duplicate value number.");
+      VNMap.insert(I, pair);
+
+      return Values.size();
+    }
+
+    /// value - returns the Value associated with a value number.
+    Value *value(unsigned index) const {
+      assert(index != 0 && "Zero index is reserved for not found.");
+      assert(index <= Values.size() && "Index out of range.");
+      return Values[index-1];
+    }
+
+    /// canonicalize - return a Value that is equal to V under Subtree.
+    Value *canonicalize(Value *V, DomTreeDFS::Node *Subtree) {
+      if (isa<Constant>(V)) return V;
+
+      if (unsigned n = valueNumber(V, Subtree))
+        return value(n);
+      else
+        return V;
+    }
+
+    /// addEquality - adds that value V belongs to the set of equivalent
+    /// values defined by value number n under Subtree.
+    void addEquality(unsigned n, Value *V, DomTreeDFS::Node *Subtree) {
+      assert(canonicalize(value(n), Subtree) == value(n) &&
+             "Node's 'canonical' choice isn't best within this subtree.");
+
+      // Suppose that we are given "%x -> node #1 (%y)". The problem is that
+      // we may already have "%z -> node #2 (%x)" somewhere above us in the
+      // graph. We need to find those edges and add "%z -> node #1 (%y)"
+      // to keep the lookups canonical.
+
+      std::vector<Value *> ToRepoint(1, V);
+
+      if (unsigned Conflict = valueNumber(V, Subtree)) {
+        for (VNMapType::iterator I = VNMap.begin(), E = VNMap.end();
+             I != E; ++I) {
+          if (I->index == Conflict && I->Subtree->dominates(Subtree))
+            ToRepoint.push_back(I->V);
+        }
+      }
+
+      for (std::vector<Value *>::iterator VI = ToRepoint.begin(),
+           VE = ToRepoint.end(); VI != VE; ++VI) {
+        Value *V = *VI;
+
+        VNPair pair(V, n, Subtree);
+        VNMapType::iterator B = VNMap.begin(), E = VNMap.end();
+        VNMapType::iterator I = std::lower_bound(B, E, pair);
+        if (I != E && I->V == V && I->Subtree == Subtree)
+          I->index = n; // Update best choice
+        else
+          VNMap.insert(I, pair); // New Value
+
+        // XXX: we currently don't have to worry about updating values with
+        // more specific Subtrees, but we will need to for PHI node support.
+
+#ifndef NDEBUG
+        Value *V_n = value(n);
+        if (isa<Constant>(V) && isa<Constant>(V_n)) {
+          assert(V == V_n && "Constant equals different constant?");
+        }
+#endif
+      }
+    }
+
+    /// remove - removes all references to value V.
+    void remove(Value *V) {
+      VNMapType::iterator B = VNMap.begin(), E = VNMap.end();
+      VNPair pair(V, 0, DTDFS->getRootNode());
+      VNMapType::iterator J = std::upper_bound(B, E, pair);
+      VNMapType::iterator I = J;
+
+      while (I != B && (I == E || I->V == V)) --I;
+
+      VNMap.erase(I, J);
+    }
+  };
+
   /// The InequalityGraph stores the relationships between values.
   /// Each Value in the graph is assigned to a Node. Nodes are pointer
   /// comparable for equality. The caller is expected to maintain the logical
@@ -172,68 +591,59 @@ namespace {
   ///
   /// The InequalityGraph class may invalidate Node*s after any mutator call.
   /// @brief The InequalityGraph stores the relationships between values.
-  class VISIBILITY_HIDDEN InequalityGraph {
-    ETNode *TreeRoot;
+  class InequalityGraph {
+    ValueNumbering &VN;
+    DomTreeDFS::Node *TreeRoot;
 
     InequalityGraph();                  // DO NOT IMPLEMENT
     InequalityGraph(InequalityGraph &); // DO NOT IMPLEMENT
   public:
-    explicit InequalityGraph(ETNode *TreeRoot) : TreeRoot(TreeRoot) {}
+    InequalityGraph(ValueNumbering &VN, DomTreeDFS::Node *TreeRoot)
+      : VN(VN), TreeRoot(TreeRoot) {}
 
     class Node;
 
-    /// This is a StrictWeakOrdering predicate that sorts ETNodes by how many
-    /// children they have. With this, you can iterate through a list sorted by
-    /// this operation and the first matching entry is the most specific match
-    /// for your basic block. The order provided is total; ETNodes with the
-    /// same number of children are sorted by pointer address.
-    struct VISIBILITY_HIDDEN OrderByDominance {
-      bool operator()(const ETNode *LHS, const ETNode *RHS) const {
-        unsigned LHS_spread = LHS->getDFSNumOut() - LHS->getDFSNumIn();
-        unsigned RHS_spread = RHS->getDFSNumOut() - RHS->getDFSNumIn();
-        if (LHS_spread != RHS_spread) return LHS_spread < RHS_spread;
-        else return LHS < RHS;
-      }
-    };
-
     /// An Edge is contained inside a Node making one end of the edge implicit
     /// and contains a pointer to the other end. The edge contains a lattice
-    /// value specifying the relationship between the two nodes. Further, there
-    /// is an ETNode specifying which subtree of the dominator the edge applies.
-    class VISIBILITY_HIDDEN Edge {
+    /// value specifying the relationship and an DomTreeDFS::Node specifying
+    /// the root in the dominator tree to which this edge applies.
+    class Edge {
     public:
-      Edge(unsigned T, LatticeVal V, ETNode *ST)
+      Edge(unsigned T, LatticeVal V, DomTreeDFS::Node *ST)
         : To(T), LV(V), Subtree(ST) {}
 
       unsigned To;
       LatticeVal LV;
-      ETNode *Subtree;
+      DomTreeDFS::Node *Subtree;
 
       bool operator<(const Edge &edge) const {
         if (To != edge.To) return To < edge.To;
-        else return OrderByDominance()(Subtree, edge.Subtree);
+        return *Subtree < *edge.Subtree;
       }
+
       bool operator<(unsigned to) const {
         return To < to;
       }
+
+      bool operator>(unsigned to) const {
+        return To > to;
+      }
+
+      friend bool operator<(unsigned to, const Edge &edge) {
+        return edge.operator>(to);
+      }
     };
 
     /// A single node in the InequalityGraph. This stores the canonical Value
     /// for the node, as well as the relationships with the neighbours.
     ///
-    /// Because the lists are intended to be used for traversal, it is invalid
-    /// for the node to list itself in LessEqual or GreaterEqual lists. The
-    /// fact that a node is equal to itself is implied, and may be checked
-    /// with pointer comparison.
     /// @brief A single node in the InequalityGraph.
-    class VISIBILITY_HIDDEN Node {
+    class Node {
       friend class InequalityGraph;
 
       typedef SmallVector<Edge, 4> RelationsType;
       RelationsType Relations;
 
-      Value *Canonical;
-
       // TODO: can this idea improve performance?
       //friend class std::vector<Node>;
       //Node(Node &N) { RelationsType.swap(N.RelationsType); }
@@ -242,39 +652,34 @@ namespace {
       typedef RelationsType::iterator       iterator;
       typedef RelationsType::const_iterator const_iterator;
 
-      Node(Value *V) : Canonical(V) {}
-
-    private:
 #ifndef NDEBUG
-    public:
       virtual ~Node() {}
       virtual void dump() const {
-        dump(*cerr.stream());
+        dump(errs());
       }
     private:
-      void dump(std::ostream &os) const  {
-        os << *getValue() << ":\n";
+      void dump(raw_ostream &os) const {
+        static const std::string names[32] =
+          { "000000", "000001", "000002", "000003", "000004", "000005",
+            "000006", "000007", "000008", "000009", "     >", "    >=",
+            "  s>u<", "s>=u<=", "    s>", "   s>=", "000016", "000017",
+            "  s<u>", "s<=u>=", "     <", "    <=", "    s<", "   s<=",
+            "000024", "000025", "    u>", "   u>=", "    u<", "   u<=",
+            "    !=", "000031" };
         for (Node::const_iterator NI = begin(), NE = end(); NI != NE; ++NI) {
-          static const std::string names[32] =
-            { "000000", "000001", "000002", "000003", "000004", "000005",
-              "000006", "000007", "000008", "000009", "     >", "    >=",
-              "  s>u<", "s>=u<=", "    s>", "   s>=", "000016", "000017",
-              "  s<u>", "s<=u>=", "     <", "    <=", "    s<", "   s<=",
-              "000024", "000025", "    u>", "   u>=", "    u<", "   u<=",
-              "    !=", "000031" };
-          os << "  " << names[NI->LV] << " " << NI->To
-             << " (" << NI->Subtree->getDFSNumIn() << ")\n";
+          os << names[NI->LV] << " " << NI->To
+             << " (" << NI->Subtree->getDFSNumIn() << "), ";
         }
       }
+    public:
 #endif
 
-    public:
       iterator begin()             { return Relations.begin(); }
       iterator end()               { return Relations.end();   }
       const_iterator begin() const { return Relations.begin(); }
       const_iterator end()   const { return Relations.end();   }
 
-      iterator find(unsigned n, ETNode *Subtree) {
+      iterator find(unsigned n, DomTreeDFS::Node *Subtree) {
         iterator E = end();
         for (iterator I = std::lower_bound(begin(), E, n);
              I != E && I->To == n; ++I) {
@@ -284,7 +689,7 @@ namespace {
         return E;
       }
 
-      const_iterator find(unsigned n, ETNode *Subtree) const {
+      const_iterator find(unsigned n, DomTreeDFS::Node *Subtree) const {
         const_iterator E = end();
         for (const_iterator I = std::lower_bound(begin(), E, n);
              I != E && I->To == n; ++I) {
@@ -294,227 +699,65 @@ namespace {
         return E;
       }
 
-      Value *getValue() const
-      {
-        return Canonical;
-      }
-
-      /// Updates the lattice value for a given node. Create a new entry if
-      /// one doesn't exist, otherwise it merges the values. The new lattice
-      /// value must not be inconsistent with any previously existing value.
-      void update(unsigned n, LatticeVal R, ETNode *Subtree) {
+      /// update - updates the lattice value for a given node, creating a new
+      /// entry if one doesn't exist. The new lattice value must not be
+      /// inconsistent with any previously existing value.
+      void update(unsigned n, LatticeVal R, DomTreeDFS::Node *Subtree) {
         assert(validPredicate(R) && "Invalid predicate.");
-        iterator I = find(n, Subtree);
-        if (I == end()) {
-          Edge edge(n, R, Subtree);
-          iterator Insert = std::lower_bound(begin(), end(), edge);
-          Relations.insert(Insert, edge);
-        } else {
-          LatticeVal LV = static_cast<LatticeVal>(I->LV & R);
-          assert(validPredicate(LV) && "Invalid union of lattice values.");
-          if (LV != I->LV) {
-            if (Subtree != I->Subtree) {
-              assert(Subtree->DominatedBy(I->Subtree) &&
-                     "Find returned subtree that doesn't apply.");
-
-              Edge edge(n, R, Subtree);
-              iterator Insert = std::lower_bound(begin(), end(), edge);
-              Relations.insert(Insert, edge); // invalidates I
-              I = find(n, Subtree);
-            }
 
-            // Also, we have to tighten any edge that Subtree dominates.
-            for (iterator B = begin(); I->To == n; --I) {
-              if (I->Subtree->DominatedBy(Subtree)) {
-                LatticeVal LV = static_cast<LatticeVal>(I->LV & R);
-                assert(validPredicate(LV) && "Invalid union of lattice values.");
-                I->LV = LV;
-              }
-              if (I == B) break;
-            }
-          }
-        }
-      }
-    };
+        Edge edge(n, R, Subtree);
+        iterator B = begin(), E = end();
+        iterator I = std::lower_bound(B, E, edge);
 
-  private:
-    struct VISIBILITY_HIDDEN NodeMapEdge {
-      Value *V;
-      unsigned index;
-      ETNode *Subtree;
+        iterator J = I;
+        while (J != E && J->To == n) {
+          if (Subtree->DominatedBy(J->Subtree))
+            break;
+          ++J;
+        }
 
-      NodeMapEdge(Value *V, unsigned index, ETNode *Subtree)
-        : V(V), index(index), Subtree(Subtree) {}
+        if (J != E && J->To == n) {
+          edge.LV = static_cast<LatticeVal>(J->LV & R);
+          assert(validPredicate(edge.LV) && "Invalid union of lattice values.");
 
-      bool operator==(const NodeMapEdge &RHS) const {
-        return V == RHS.V &&
-               Subtree == RHS.Subtree;
-      }
+          if (edge.LV == J->LV)
+            return; // This update adds nothing new.
+        }
 
-      bool operator<(const NodeMapEdge &RHS) const {
-        if (V != RHS.V) return V < RHS.V;
-        return OrderByDominance()(Subtree, RHS.Subtree);
-      }
+        if (I != B) {
+          // We also have to tighten any edge beneath our update.
+          for (iterator K = I - 1; K->To == n; --K) {
+            if (K->Subtree->DominatedBy(Subtree)) {
+              LatticeVal LV = static_cast<LatticeVal>(K->LV & edge.LV);
+              assert(validPredicate(LV) && "Invalid union of lattice values");
+              K->LV = LV;
+            }
+            if (K == B) break;
+          }
+        }
 
-      bool operator<(Value *RHS) const {
-        return V < RHS;
+        // Insert new edge at Subtree if it isn't already there.
+        if (I == E || I->To != n || Subtree != I->Subtree)
+          Relations.insert(I, edge);
       }
     };
 
-    typedef std::vector<NodeMapEdge> NodeMapType;
-    NodeMapType NodeMap;
+  private:
 
     std::vector<Node> Nodes;
 
-    std::vector<std::pair<ConstantInt *, unsigned> > Ints;
-
-    /// This is used to keep the ConstantInts list in unsigned ascending order.
-    /// If the bitwidths don't match, this sorts smaller values ahead.
-    struct SortByZExt {
-      bool operator()(const std::pair<ConstantInt *, unsigned> &LHS,
-                      const std::pair<ConstantInt *, unsigned> &RHS) const {
-        if (LHS.first->getType()->getBitWidth() !=
-            RHS.first->getType()->getBitWidth())
-          return LHS.first->getType()->getBitWidth() <
-                 RHS.first->getType()->getBitWidth();
-        return LHS.first->getZExtValue() < RHS.first->getZExtValue();
-      }
-    };
-
-    /// True when the bitwidth of LHS < bitwidth of RHS.
-    struct FindByIntegerWidth {
-      bool operator()(const std::pair<ConstantInt *, unsigned> &LHS,
-                      const std::pair<ConstantInt *, unsigned> &RHS) const {
-        return LHS.first->getType()->getBitWidth() <
-               RHS.first->getType()->getBitWidth();
-      }
-    };
-
-    void initializeInt(ConstantInt *CI, unsigned index) {
-      std::vector<std::pair<ConstantInt *, unsigned> >::iterator begin, end,
-          last, iULT, iUGT, iSLT, iSGT;
-
-      std::pair<ConstantInt *, unsigned> pair = std::make_pair(CI, index);
-
-      begin = std::lower_bound(Ints.begin(), Ints.end(), pair,
-                               FindByIntegerWidth());
-      end   = std::upper_bound(begin, Ints.end(), pair, FindByIntegerWidth());
-
-      if (begin == end) last = end;
-      else last = end - 1;
-
-      iUGT = std::lower_bound(begin, end, pair, SortByZExt());
-      iULT = (iUGT == begin || begin == end) ? end : iUGT - 1;
-
-      if (iUGT != end && iULT != end &&
-          (iULT->first->getSExtValue() >> 63) ==
-          (iUGT->first->getSExtValue() >> 63)) { // signs match
-        iSGT = iUGT;
-        iSLT = iULT;
-      } else {
-        if (iULT == end || iUGT == end) {
-          if (iULT == end) iSLT = last;  else iSLT = iULT;
-          if (iUGT == end) iSGT = begin; else iSGT = iUGT;
-	} else if (iULT->first->getSExtValue() < 0) {
-          assert(iUGT->first->getSExtValue() >= 0 && "Bad sign comparison.");
-          iSGT = iUGT;
-          iSLT = iULT;
-        } else {
-          assert(iULT->first->getSExtValue() >= 0 &&
-                 iUGT->first->getSExtValue() < 0 && "Bad sign comparison.");
-          iSGT = iULT;
-          iSLT = iUGT;
-	}
-
-        if (iSGT != end &&
-            iSGT->first->getSExtValue() < CI->getSExtValue()) iSGT = end;
-        if (iSLT != end &&
-            iSLT->first->getSExtValue() > CI->getSExtValue()) iSLT = end;
-
-        if (begin != end) {
-          if (begin->first->getSExtValue() < CI->getSExtValue())
-            if (iSLT == end ||
-                begin->first->getSExtValue() > iSLT->first->getSExtValue())
-              iSLT = begin;
-	}
-        if (last != end) {
-          if (last->first->getSExtValue() > CI->getSExtValue())
-            if (iSGT == end ||
-                last->first->getSExtValue() < iSGT->first->getSExtValue())
-              iSGT = last;
-	}
-      }
-
-      if (iULT != end) addInequality(iULT->second, index, TreeRoot, ULT);
-      if (iUGT != end) addInequality(iUGT->second, index, TreeRoot, UGT);
-      if (iSLT != end) addInequality(iSLT->second, index, TreeRoot, SLT);
-      if (iSGT != end) addInequality(iSGT->second, index, TreeRoot, SGT);
-
-      Ints.insert(iUGT, pair);
-    }
-
   public:
-    /// node - returns the node object at a given index retrieved from getNode.
-    /// Index zero is reserved and may not be passed in here. The pointer
-    /// returned is valid until the next call to newNode or getOrInsertNode.
+    /// node - returns the node object at a given value number. The pointer
+    /// returned may be invalidated on the next call to node().
     Node *node(unsigned index) {
-      assert(index != 0 && "Zero index is reserved for not found.");
-      assert(index <= Nodes.size() && "Index out of range.");
+      assert(VN.value(index)); // This triggers the necessary checks.
+      if (Nodes.size() < index) Nodes.resize(index);
       return &Nodes[index-1];
     }
 
-    /// Returns the node currently representing Value V, or zero if no such
-    /// node exists.
-    unsigned getNode(Value *V, ETNode *Subtree) {
-      NodeMapType::iterator E = NodeMap.end();
-      NodeMapEdge Edge(V, 0, Subtree);
-      NodeMapType::iterator I = std::lower_bound(NodeMap.begin(), E, Edge);
-      while (I != E && I->V == V) {
-        if (Subtree->DominatedBy(I->Subtree))
-          return I->index;
-        ++I;
-      }
-      return 0;
-    }
-
-    /// getOrInsertNode - always returns a valid node index, creating a node
-    /// to match the Value if needed.
-    unsigned getOrInsertNode(Value *V, ETNode *Subtree) {
-      if (unsigned n = getNode(V, Subtree))
-        return n;
-      else
-        return newNode(V);
-    }
-
-    /// newNode - creates a new node for a given Value and returns the index.
-    unsigned newNode(Value *V) {
-      Nodes.push_back(Node(V));
-
-      NodeMapEdge MapEntry = NodeMapEdge(V, Nodes.size(), TreeRoot);
-      assert(!std::binary_search(NodeMap.begin(), NodeMap.end(), MapEntry) &&
-             "Attempt to create a duplicate Node.");
-      NodeMap.insert(std::lower_bound(NodeMap.begin(), NodeMap.end(),
-                                      MapEntry), MapEntry);
-
-      if (ConstantInt *CI = dyn_cast<ConstantInt>(V))
-        initializeInt(CI, MapEntry.index);
-
-      return MapEntry.index;
-    }
-
-    /// If the Value is in the graph, return the canonical form. Otherwise,
-    /// return the original Value.
-    Value *canonicalize(Value *V, ETNode *Subtree) {
-      if (isa<Constant>(V)) return V;
-
-      if (unsigned n = getNode(V, Subtree))
-        return node(n)->getValue();
-      else 
-        return V;
-    }
-
     /// isRelatedBy - true iff n1 op n2
-    bool isRelatedBy(unsigned n1, unsigned n2, ETNode *Subtree, LatticeVal LV) {
+    bool isRelatedBy(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree,
+                     LatticeVal LV) {
       if (n1 == n2) return LV & EQ_BIT;
 
       Node *N1 = node(n1);
@@ -527,57 +770,9 @@ namespace {
     // The add* methods assume that your input is logically valid and may 
     // assertion-fail or infinitely loop if you attempt a contradiction.
 
-    void addEquality(unsigned n, Value *V, ETNode *Subtree) {
-      assert(canonicalize(node(n)->getValue(), Subtree) == node(n)->getValue()
-             && "Node's 'canonical' choice isn't best within this subtree.");
-
-      // Suppose that we are given "%x -> node #1 (%y)". The problem is that
-      // we may already have "%z -> node #2 (%x)" somewhere above us in the
-      // graph. We need to find those edges and add "%z -> node #1 (%y)"
-      // to keep the lookups canonical.
-
-      std::vector<Value *> ToRepoint;
-      ToRepoint.push_back(V);
-
-      if (unsigned Conflict = getNode(V, Subtree)) {
-        // XXX: NodeMap.size() exceeds 68,000 entries compiling kimwitu++!
-        for (NodeMapType::iterator I = NodeMap.begin(), E = NodeMap.end();
-             I != E; ++I) {
-          if (I->index == Conflict && Subtree->DominatedBy(I->Subtree))
-            ToRepoint.push_back(I->V);
-        }
-      }
-
-      for (std::vector<Value *>::iterator VI = ToRepoint.begin(),
-           VE = ToRepoint.end(); VI != VE; ++VI) {
-        Value *V = *VI;
-
-        // XXX: review this code. This may be doing too many insertions.
-        NodeMapEdge Edge(V, n, Subtree);
-        NodeMapType::iterator E = NodeMap.end();
-        NodeMapType::iterator I = std::lower_bound(NodeMap.begin(), E, Edge);
-        if (I == E || I->V != V || I->Subtree != Subtree) {
-          // New Value
-          NodeMap.insert(I, Edge);
-        } else if (I != E && I->V == V && I->Subtree == Subtree) {
-          // Update best choice
-          I->index = n;
-        }
-
-#ifndef NDEBUG
-        Node *N = node(n);
-        if (isa<Constant>(V)) {
-          if (isa<Constant>(N->getValue())) {
-            assert(V == N->getValue() && "Constant equals different constant?");
-          }
-        }
-#endif
-      }
-    }
-
     /// addInequality - Sets n1 op n2.
     /// It is also an error to call this on an inequality that is already true.
-    void addInequality(unsigned n1, unsigned n2, ETNode *Subtree,
+    void addInequality(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree,
                        LatticeVal LV1) {
       assert(n1 != n2 && "A node can't be inequal to itself.");
 
@@ -585,22 +780,21 @@ namespace {
         assert(!isRelatedBy(n1, n2, Subtree, reversePredicate(LV1)) &&
                "Contradictory inequality.");
 
-      Node *N1 = node(n1);
-      Node *N2 = node(n2);
-
       // Suppose we're adding %n1 < %n2. Find all the %a < %n1 and
       // add %a < %n2 too. This keeps the graph fully connected.
       if (LV1 != NE) {
-        // Someone with a head for this sort of logic, please review this.
-        // Given that %x SLTUGT %y and %a SLE %x, what is the relationship
-        // between %a and %y? I believe the below code is correct, but I don't
-        // think it's the most efficient solution.
+        // Break up the relationship into signed and unsigned comparison parts.
+        // If the signed parts of %a op1 %n1 match that of %n1 op2 %n2, and
+        // op1 and op2 aren't NE, then add %a op3 %n2. The new relationship
+        // should have the EQ_BIT iff it's set for both op1 and op2.
 
         unsigned LV1_s = LV1 & (SLT_BIT|SGT_BIT);
         unsigned LV1_u = LV1 & (ULT_BIT|UGT_BIT);
-        for (Node::iterator I = N1->begin(), E = N1->end(); I != E; ++I) {
+
+        for (Node::iterator I = node(n1)->begin(), E = node(n1)->end(); I != E; ++I) {
           if (I->LV != NE && I->To != n2) {
-            ETNode *Local_Subtree = NULL;
+
+            DomTreeDFS::Node *Local_Subtree = NULL;
             if (Subtree->DominatedBy(I->Subtree))
               Local_Subtree = Subtree;
             else if (I->Subtree->DominatedBy(Subtree))
@@ -614,7 +808,6 @@ namespace {
 
               if (LV1_s != (SLT_BIT|SGT_BIT) && ILV_s == LV1_s)
                 new_relationship |= ILV_s;
-
               if (LV1_u != (ULT_BIT|UGT_BIT) && ILV_u == LV1_u)
                 new_relationship |= ILV_u;
 
@@ -626,103 +819,457 @@ namespace {
                 if ((LV1 & EQ_BIT) && (ILV & EQ_BIT))
                   new_relationship |= EQ_BIT;
 
-                LatticeVal NewLV = static_cast<LatticeVal>(new_relationship);
+                LatticeVal NewLV = static_cast<LatticeVal>(new_relationship);
+
+                node(I->To)->update(n2, NewLV, Local_Subtree);
+                node(n2)->update(I->To, reversePredicate(NewLV), Local_Subtree);
+              }
+            }
+          }
+        }
+
+        for (Node::iterator I = node(n2)->begin(), E = node(n2)->end(); I != E; ++I) {
+          if (I->LV != NE && I->To != n1) {
+            DomTreeDFS::Node *Local_Subtree = NULL;
+            if (Subtree->DominatedBy(I->Subtree))
+              Local_Subtree = Subtree;
+            else if (I->Subtree->DominatedBy(Subtree))
+              Local_Subtree = I->Subtree;
+
+            if (Local_Subtree) {
+              unsigned new_relationship = 0;
+              unsigned ILV_s = I->LV & (SLT_BIT|SGT_BIT);
+              unsigned ILV_u = I->LV & (ULT_BIT|UGT_BIT);
+
+              if (LV1_s != (SLT_BIT|SGT_BIT) && ILV_s == LV1_s)
+                new_relationship |= ILV_s;
+
+              if (LV1_u != (ULT_BIT|UGT_BIT) && ILV_u == LV1_u)
+                new_relationship |= ILV_u;
+
+              if (new_relationship) {
+                if ((new_relationship & (SLT_BIT|SGT_BIT)) == 0)
+                  new_relationship |= (SLT_BIT|SGT_BIT);
+                if ((new_relationship & (ULT_BIT|UGT_BIT)) == 0)
+                  new_relationship |= (ULT_BIT|UGT_BIT);
+                if ((LV1 & EQ_BIT) && (I->LV & EQ_BIT))
+                  new_relationship |= EQ_BIT;
+
+                LatticeVal NewLV = static_cast<LatticeVal>(new_relationship);
+
+                node(n1)->update(I->To, NewLV, Local_Subtree);
+                node(I->To)->update(n1, reversePredicate(NewLV), Local_Subtree);
+              }
+            }
+          }
+        }
+      }
+
+      node(n1)->update(n2, LV1, Subtree);
+      node(n2)->update(n1, reversePredicate(LV1), Subtree);
+    }
+
+    /// remove - removes a node from the graph by removing all references to
+    /// and from it.
+    void remove(unsigned n) {
+      Node *N = node(n);
+      for (Node::iterator NI = N->begin(), NE = N->end(); NI != NE; ++NI) {
+        Node::iterator Iter = node(NI->To)->find(n, TreeRoot);
+        do {
+          node(NI->To)->Relations.erase(Iter);
+          Iter = node(NI->To)->find(n, TreeRoot);
+        } while (Iter != node(NI->To)->end());
+      }
+      N->Relations.clear();
+    }
+
+#ifndef NDEBUG
+    virtual ~InequalityGraph() {}
+    virtual void dump() {
+      dump(errs());
+    }
+
+    void dump(raw_ostream &os) {
+      for (unsigned i = 1; i <= Nodes.size(); ++i) {
+        os << i << " = {";
+        node(i)->dump(os);
+        os << "}\n";
+      }
+    }
+#endif
+  };
+
+  class VRPSolver;
+
+  /// ValueRanges tracks the known integer ranges and anti-ranges of the nodes
+  /// in the InequalityGraph.
+  class ValueRanges {
+    ValueNumbering &VN;
+    TargetData *TD;
+    LLVMContext *Context;
+
+    class ScopedRange {
+      typedef std::vector<std::pair<DomTreeDFS::Node *, ConstantRange> >
+              RangeListType;
+      RangeListType RangeList;
+
+      static bool swo(const std::pair<DomTreeDFS::Node *, ConstantRange> &LHS,
+                      const std::pair<DomTreeDFS::Node *, ConstantRange> &RHS) {
+        return *LHS.first < *RHS.first;
+      }
+
+    public:
+#ifndef NDEBUG
+      virtual ~ScopedRange() {}
+      virtual void dump() const {
+        dump(errs());
+      }
+
+      void dump(raw_ostream &os) const {
+        os << "{";
+        for (const_iterator I = begin(), E = end(); I != E; ++I) {
+          os << &I->second << " (" << I->first->getDFSNumIn() << "), ";
+        }
+        os << "}";
+      }
+#endif
+
+      typedef RangeListType::iterator       iterator;
+      typedef RangeListType::const_iterator const_iterator;
+
+      iterator begin() { return RangeList.begin(); }
+      iterator end()   { return RangeList.end(); }
+      const_iterator begin() const { return RangeList.begin(); }
+      const_iterator end()   const { return RangeList.end(); }
+
+      iterator find(DomTreeDFS::Node *Subtree) {
+        iterator E = end();
+        iterator I = std::lower_bound(begin(), E,
+                                      std::make_pair(Subtree, empty), swo);
+
+        while (I != E && !I->first->dominates(Subtree)) ++I;
+        return I;
+      }
+
+      const_iterator find(DomTreeDFS::Node *Subtree) const {
+        const_iterator E = end();
+        const_iterator I = std::lower_bound(begin(), E,
+                                            std::make_pair(Subtree, empty), swo);
+
+        while (I != E && !I->first->dominates(Subtree)) ++I;
+        return I;
+      }
+
+      void update(const ConstantRange &CR, DomTreeDFS::Node *Subtree) {
+        assert(!CR.isEmptySet() && "Empty ConstantRange.");
+        assert(!CR.isSingleElement() && "Refusing to store single element.");
+
+        iterator E = end();
+        iterator I =
+            std::lower_bound(begin(), E, std::make_pair(Subtree, empty), swo);
+
+        if (I != end() && I->first == Subtree) {
+          ConstantRange CR2 = I->second.intersectWith(CR);
+          assert(!CR2.isEmptySet() && !CR2.isSingleElement() &&
+                 "Invalid union of ranges.");
+          I->second = CR2;
+        } else
+          RangeList.insert(I, std::make_pair(Subtree, CR));
+      }
+    };
+
+    std::vector<ScopedRange> Ranges;
+
+    void update(unsigned n, const ConstantRange &CR, DomTreeDFS::Node *Subtree){
+      if (CR.isFullSet()) return;
+      if (Ranges.size() < n) Ranges.resize(n);
+      Ranges[n-1].update(CR, Subtree);
+    }
+
+    /// create - Creates a ConstantRange that matches the given LatticeVal
+    /// relation with a given integer.
+    ConstantRange create(LatticeVal LV, const ConstantRange &CR) {
+      assert(!CR.isEmptySet() && "Can't deal with empty set.");
+
+      if (LV == NE)
+        return ConstantRange::makeICmpRegion(ICmpInst::ICMP_NE, CR);
+
+      unsigned LV_s = LV & (SGT_BIT|SLT_BIT);
+      unsigned LV_u = LV & (UGT_BIT|ULT_BIT);
+      bool hasEQ = LV & EQ_BIT;
+
+      ConstantRange Range(CR.getBitWidth());
+
+      if (LV_s == SGT_BIT) {
+        Range = Range.intersectWith(ConstantRange::makeICmpRegion(
+                    hasEQ ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_SGT, CR));
+      } else if (LV_s == SLT_BIT) {
+        Range = Range.intersectWith(ConstantRange::makeICmpRegion(
+                    hasEQ ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_SLT, CR));
+      }
+
+      if (LV_u == UGT_BIT) {
+        Range = Range.intersectWith(ConstantRange::makeICmpRegion(
+                    hasEQ ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_UGT, CR));
+      } else if (LV_u == ULT_BIT) {
+        Range = Range.intersectWith(ConstantRange::makeICmpRegion(
+                    hasEQ ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_ULT, CR));
+      }
+
+      return Range;
+    }
+
+#ifndef NDEBUG
+    bool isCanonical(Value *V, DomTreeDFS::Node *Subtree) {
+      return V == VN.canonicalize(V, Subtree);
+    }
+#endif
+
+  public:
+
+    ValueRanges(ValueNumbering &VN, TargetData *TD, LLVMContext *C) :
+      VN(VN), TD(TD), Context(C) {}
+
+#ifndef NDEBUG
+    virtual ~ValueRanges() {}
+
+    virtual void dump() const {
+      dump(errs());
+    }
+
+    void dump(raw_ostream &os) const {
+      for (unsigned i = 0, e = Ranges.size(); i != e; ++i) {
+        os << (i+1) << " = ";
+        Ranges[i].dump(os);
+        os << "\n";
+      }
+    }
+#endif
+
+    /// range - looks up the ConstantRange associated with a value number.
+    ConstantRange range(unsigned n, DomTreeDFS::Node *Subtree) {
+      assert(VN.value(n)); // performs range checks
+
+      if (n <= Ranges.size()) {
+        ScopedRange::iterator I = Ranges[n-1].find(Subtree);
+        if (I != Ranges[n-1].end()) return I->second;
+      }
+
+      Value *V = VN.value(n);
+      ConstantRange CR = range(V);
+      return CR;
+    }
+
+    /// range - determine a range from a Value without performing any lookups.
+    ConstantRange range(Value *V) const {
+      if (ConstantInt *C = dyn_cast<ConstantInt>(V))
+        return ConstantRange(C->getValue());
+      else if (isa<ConstantPointerNull>(V))
+        return ConstantRange(APInt::getNullValue(typeToWidth(V->getType())));
+      else
+        return ConstantRange(typeToWidth(V->getType()));
+    }
+
+    // typeToWidth - returns the number of bits necessary to store a value of
+    // this type, or zero if unknown.
+    uint32_t typeToWidth(const Type *Ty) const {
+      if (TD)
+        return TD->getTypeSizeInBits(Ty);
+      else
+        return Ty->getPrimitiveSizeInBits();
+    }
+
+    static bool isRelatedBy(const ConstantRange &CR1, const ConstantRange &CR2,
+                            LatticeVal LV) {
+      switch (LV) {
+      default: assert(!"Impossible lattice value!");
+      case NE:
+        return CR1.intersectWith(CR2).isEmptySet();
+      case ULT:
+        return CR1.getUnsignedMax().ult(CR2.getUnsignedMin());
+      case ULE:
+        return CR1.getUnsignedMax().ule(CR2.getUnsignedMin());
+      case UGT:
+        return CR1.getUnsignedMin().ugt(CR2.getUnsignedMax());
+      case UGE:
+        return CR1.getUnsignedMin().uge(CR2.getUnsignedMax());
+      case SLT:
+        return CR1.getSignedMax().slt(CR2.getSignedMin());
+      case SLE:
+        return CR1.getSignedMax().sle(CR2.getSignedMin());
+      case SGT:
+        return CR1.getSignedMin().sgt(CR2.getSignedMax());
+      case SGE:
+        return CR1.getSignedMin().sge(CR2.getSignedMax());
+      case LT:
+        return CR1.getUnsignedMax().ult(CR2.getUnsignedMin()) &&
+               CR1.getSignedMax().slt(CR2.getUnsignedMin());
+      case LE:
+        return CR1.getUnsignedMax().ule(CR2.getUnsignedMin()) &&
+               CR1.getSignedMax().sle(CR2.getUnsignedMin());
+      case GT:
+        return CR1.getUnsignedMin().ugt(CR2.getUnsignedMax()) &&
+               CR1.getSignedMin().sgt(CR2.getSignedMax());
+      case GE:
+        return CR1.getUnsignedMin().uge(CR2.getUnsignedMax()) &&
+               CR1.getSignedMin().sge(CR2.getSignedMax());
+      case SLTUGT:
+        return CR1.getSignedMax().slt(CR2.getSignedMin()) &&
+               CR1.getUnsignedMin().ugt(CR2.getUnsignedMax());
+      case SLEUGE:
+        return CR1.getSignedMax().sle(CR2.getSignedMin()) &&
+               CR1.getUnsignedMin().uge(CR2.getUnsignedMax());
+      case SGTULT:
+        return CR1.getSignedMin().sgt(CR2.getSignedMax()) &&
+               CR1.getUnsignedMax().ult(CR2.getUnsignedMin());
+      case SGEULE:
+        return CR1.getSignedMin().sge(CR2.getSignedMax()) &&
+               CR1.getUnsignedMax().ule(CR2.getUnsignedMin());
+      }
+    }
 
-                node(I->To)->update(n2, NewLV, Local_Subtree);
-                N2->update(I->To, reversePredicate(NewLV), Local_Subtree);
-              }
-            }
-          }
-        }
+    bool isRelatedBy(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree,
+                     LatticeVal LV) {
+      ConstantRange CR1 = range(n1, Subtree);
+      ConstantRange CR2 = range(n2, Subtree);
 
-        for (Node::iterator I = N2->begin(), E = N2->end(); I != E; ++I) {
-          if (I->LV != NE && I->To != n1) {
-            ETNode *Local_Subtree = NULL;
-            if (Subtree->DominatedBy(I->Subtree))
-              Local_Subtree = Subtree;
-            else if (I->Subtree->DominatedBy(Subtree))
-              Local_Subtree = I->Subtree;
+      // True iff all values in CR1 are LV to all values in CR2.
+      return isRelatedBy(CR1, CR2, LV);
+    }
 
-            if (Local_Subtree) {
-              unsigned new_relationship = 0;
-              unsigned ILV_s = I->LV & (SLT_BIT|SGT_BIT);
-              unsigned ILV_u = I->LV & (ULT_BIT|UGT_BIT);
+    void addToWorklist(Value *V, Constant *C, ICmpInst::Predicate Pred,
+                       VRPSolver *VRP);
+    void markBlock(VRPSolver *VRP);
 
-              if (LV1_s != (SLT_BIT|SGT_BIT) && ILV_s == LV1_s)
-                new_relationship |= ILV_s;
+    void mergeInto(Value **I, unsigned n, unsigned New,
+                   DomTreeDFS::Node *Subtree, VRPSolver *VRP) {
+      ConstantRange CR_New = range(New, Subtree);
+      ConstantRange Merged = CR_New;
 
-              if (LV1_u != (ULT_BIT|UGT_BIT) && ILV_u == LV1_u)
-                new_relationship |= ILV_u;
+      for (; n != 0; ++I, --n) {
+        unsigned i = VN.valueNumber(*I, Subtree);
+        ConstantRange CR_Kill = i ? range(i, Subtree) : range(*I);
+        if (CR_Kill.isFullSet()) continue;
+        Merged = Merged.intersectWith(CR_Kill);
+      }
 
-              if (new_relationship) {
-                if ((new_relationship & (SLT_BIT|SGT_BIT)) == 0)
-                  new_relationship |= (SLT_BIT|SGT_BIT);
-                if ((new_relationship & (ULT_BIT|UGT_BIT)) == 0)
-                  new_relationship |= (ULT_BIT|UGT_BIT);
-                if ((LV1 & EQ_BIT) && (I->LV & EQ_BIT))
-                  new_relationship |= EQ_BIT;
+      if (Merged.isFullSet() || Merged == CR_New) return;
 
-                LatticeVal NewLV = static_cast<LatticeVal>(new_relationship);
+      applyRange(New, Merged, Subtree, VRP);
+    }
 
-                N1->update(I->To, NewLV, Local_Subtree);
-                node(I->To)->update(n1, reversePredicate(NewLV), Local_Subtree);
-              }
-            }
-          }
+    void applyRange(unsigned n, const ConstantRange &CR,
+                    DomTreeDFS::Node *Subtree, VRPSolver *VRP) {
+      ConstantRange Merged = CR.intersectWith(range(n, Subtree));
+      if (Merged.isEmptySet()) {
+        markBlock(VRP);
+        return;
+      }
+
+      if (const APInt *I = Merged.getSingleElement()) {
+        Value *V = VN.value(n); // XXX: redesign worklist.
+        const Type *Ty = V->getType();
+        if (Ty->isInteger()) {
+          addToWorklist(V, ConstantInt::get(*Context, *I),
+                        ICmpInst::ICMP_EQ, VRP);
+          return;
+        } else if (const PointerType *PTy = dyn_cast<PointerType>(Ty)) {
+          assert(*I == 0 && "Pointer is null but not zero?");
+          addToWorklist(V, ConstantPointerNull::get(PTy),
+                        ICmpInst::ICMP_EQ, VRP);
+          return;
         }
       }
 
-      N1->update(n2, LV1, Subtree);
-      N2->update(n1, reversePredicate(LV1), Subtree);
+      update(n, Merged, Subtree);
     }
 
-    /// Removes a Value from the graph, but does not delete any nodes. As this
-    /// method does not delete Nodes, V may not be the canonical choice for
-    /// a node with any relationships. It is invalid to call newNode on a Value
-    /// that has been removed.
-    void remove(Value *V) {
-      for (unsigned i = 0; i < NodeMap.size();) {
-        NodeMapType::iterator I = NodeMap.begin()+i;
-        assert((node(I->index)->getValue() != V || node(I->index)->begin() ==
-                node(I->index)->end()) && "Tried to delete in-use node.");
-        if (I->V == V) {
-#ifndef NDEBUG
-          if (node(I->index)->getValue() == V)
-            node(I->index)->Canonical = NULL;
-#endif
-          NodeMap.erase(I);
-        } else ++i;
+    void addNotEquals(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree,
+                      VRPSolver *VRP) {
+      ConstantRange CR1 = range(n1, Subtree);
+      ConstantRange CR2 = range(n2, Subtree);
+
+      uint32_t W = CR1.getBitWidth();
+
+      if (const APInt *I = CR1.getSingleElement()) {
+        if (CR2.isFullSet()) {
+          ConstantRange NewCR2(CR1.getUpper(), CR1.getLower());
+          applyRange(n2, NewCR2, Subtree, VRP);
+        } else if (*I == CR2.getLower()) {
+          APInt NewLower(CR2.getLower() + 1),
+                NewUpper(CR2.getUpper());
+          if (NewLower == NewUpper)
+            NewLower = NewUpper = APInt::getMinValue(W);
+
+          ConstantRange NewCR2(NewLower, NewUpper);
+          applyRange(n2, NewCR2, Subtree, VRP);
+        } else if (*I == CR2.getUpper() - 1) {
+          APInt NewLower(CR2.getLower()),
+                NewUpper(CR2.getUpper() - 1);
+          if (NewLower == NewUpper)
+            NewLower = NewUpper = APInt::getMinValue(W);
+
+          ConstantRange NewCR2(NewLower, NewUpper);
+          applyRange(n2, NewCR2, Subtree, VRP);
+        }
       }
-    }
 
-#ifndef NDEBUG
-    virtual ~InequalityGraph() {}
-    virtual void dump() {
-      dump(*cerr.stream());
+      if (const APInt *I = CR2.getSingleElement()) {
+        if (CR1.isFullSet()) {
+          ConstantRange NewCR1(CR2.getUpper(), CR2.getLower());
+          applyRange(n1, NewCR1, Subtree, VRP);
+        } else if (*I == CR1.getLower()) {
+          APInt NewLower(CR1.getLower() + 1),
+                NewUpper(CR1.getUpper());
+          if (NewLower == NewUpper)
+            NewLower = NewUpper = APInt::getMinValue(W);
+
+          ConstantRange NewCR1(NewLower, NewUpper);
+          applyRange(n1, NewCR1, Subtree, VRP);
+        } else if (*I == CR1.getUpper() - 1) {
+          APInt NewLower(CR1.getLower()),
+                NewUpper(CR1.getUpper() - 1);
+          if (NewLower == NewUpper)
+            NewLower = NewUpper = APInt::getMinValue(W);
+
+          ConstantRange NewCR1(NewLower, NewUpper);
+          applyRange(n1, NewCR1, Subtree, VRP);
+        }
+      }
     }
 
-    void dump(std::ostream &os) {
-    std::set<Node *> VisitedNodes;
-    for (NodeMapType::const_iterator I = NodeMap.begin(), E = NodeMap.end();
-         I != E; ++I) {
-      Node *N = node(I->index);
-      os << *I->V << " == " << I->index
-         << "(" << I->Subtree->getDFSNumIn() << ")\n";
-      if (VisitedNodes.insert(N).second) {
-        os << I->index << ". ";
-        if (!N->getValue()) os << "(deleted node)\n";
-        else N->dump(os);
+    void addInequality(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree,
+                       LatticeVal LV, VRPSolver *VRP) {
+      assert(!isRelatedBy(n1, n2, Subtree, LV) && "Asked to do useless work.");
+
+      if (LV == NE) {
+        addNotEquals(n1, n2, Subtree, VRP);
+        return;
+      }
+
+      ConstantRange CR1 = range(n1, Subtree);
+      ConstantRange CR2 = range(n2, Subtree);
+
+      if (!CR1.isSingleElement()) {
+        ConstantRange NewCR1 = CR1.intersectWith(create(LV, CR2));
+        if (NewCR1 != CR1)
+          applyRange(n1, NewCR1, Subtree, VRP);
+      }
+
+      if (!CR2.isSingleElement()) {
+        ConstantRange NewCR2 = CR2.intersectWith(
+                                       create(reversePredicate(LV), CR1));
+        if (NewCR2 != CR2)
+          applyRange(n2, NewCR2, Subtree, VRP);
       }
     }
-  }
-#endif
   };
 
   /// UnreachableBlocks keeps tracks of blocks that are for one reason or
   /// another discovered to be unreachable. This is used to cull the graph when
   /// analyzing instructions, and to mark blocks with the "unreachable"
   /// terminator instruction after the function has executed.
-  class VISIBILITY_HIDDEN UnreachableBlocks {
+  class UnreachableBlocks {
   private:
     std::vector<BasicBlock *> DeadBlocks;
 
@@ -752,7 +1299,7 @@ namespace {
            E = DeadBlocks.end(); I != E; ++I) {
         BasicBlock *BB = *I;
 
-        DOUT << "unreachable block: " << BB->getName() << "\n";
+        DEBUG(errs() << "unreachable block: " << BB->getName() << "\n");
 
         for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
              SI != SE; ++SI) {
@@ -763,7 +1310,7 @@ namespace {
         TerminatorInst *TI = BB->getTerminator();
         TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
         TI->eraseFromParent();
-        new UnreachableInst(BB);
+        new UnreachableInst(BB->getContext(), BB);
         ++NumBlocks;
         modified = true;
       }
@@ -776,99 +1323,94 @@ namespace {
   /// variables, and forwards changes along to the InequalityGraph. It
   /// also maintains the correct choice for "canonical" in the IG.
   /// @brief VRPSolver calculates inferences from a new relationship.
-  class VISIBILITY_HIDDEN VRPSolver {
+  class VRPSolver {
   private:
+    friend class ValueRanges;
+
     struct Operation {
       Value *LHS, *RHS;
       ICmpInst::Predicate Op;
 
-      BasicBlock *ContextBB;
+      BasicBlock *ContextBB; // XXX use a DomTreeDFS::Node instead
       Instruction *ContextInst;
     };
     std::deque<Operation> WorkList;
 
+    ValueNumbering &VN;
     InequalityGraph &IG;
     UnreachableBlocks &UB;
-    ETForest *Forest;
-    ETNode *Top;
+    ValueRanges &VR;
+    DomTreeDFS *DTDFS;
+    DomTreeDFS::Node *Top;
     BasicBlock *TopBB;
     Instruction *TopInst;
     bool &modified;
+    LLVMContext *Context;
 
     typedef InequalityGraph::Node Node;
 
-    /// IdomI - Determines whether one Instruction dominates another.
-    bool IdomI(Instruction *I1, Instruction *I2) const {
-      BasicBlock *BB1 = I1->getParent(),
-                 *BB2 = I2->getParent();
-      if (BB1 == BB2) {
-        if (isa<TerminatorInst>(I1)) return false;
-        if (isa<TerminatorInst>(I2)) return true;
-        if (isa<PHINode>(I1) && !isa<PHINode>(I2)) return true;
-        if (!isa<PHINode>(I1) && isa<PHINode>(I2)) return false;
-
-        for (BasicBlock::const_iterator I = BB1->begin(), E = BB1->end();
-             I != E; ++I) {
-          if (&*I == I1) return true;
-          if (&*I == I2) return false;
+    // below - true if the Instruction is dominated by the current context
+    // block or instruction
+    bool below(Instruction *I) {
+      BasicBlock *BB = I->getParent();
+      if (TopInst && TopInst->getParent() == BB) {
+        if (isa<TerminatorInst>(TopInst)) return false;
+        if (isa<TerminatorInst>(I)) return true;
+        if ( isa<PHINode>(TopInst) && !isa<PHINode>(I)) return true;
+        if (!isa<PHINode>(TopInst) &&  isa<PHINode>(I)) return false;
+
+        for (BasicBlock::const_iterator Iter = BB->begin(), E = BB->end();
+             Iter != E; ++Iter) {
+          if (&*Iter == TopInst) return true;
+          else if (&*Iter == I) return false;
         }
         assert(!"Instructions not found in parent BasicBlock?");
       } else {
-        return Forest->properlyDominates(BB1, BB2);
+        DomTreeDFS::Node *Node = DTDFS->getNodeForBlock(BB);
+        if (!Node) return false;
+        return Top->dominates(Node);
       }
-      return false;
+      return false; // Not reached
     }
 
-    /// Returns true if V1 is a better canonical value than V2.
-    bool compare(Value *V1, Value *V2) const {
-      if (isa<Constant>(V1))
-        return !isa<Constant>(V2);
-      else if (isa<Constant>(V2))
-        return false;
-      else if (isa<Argument>(V1))
-        return !isa<Argument>(V2);
-      else if (isa<Argument>(V2))
-        return false;
-
-      Instruction *I1 = dyn_cast<Instruction>(V1);
-      Instruction *I2 = dyn_cast<Instruction>(V2);
-
-      if (!I1 || !I2)
-        return V1->getNumUses() < V2->getNumUses();
-
-      return IdomI(I1, I2);
-    }
+    // aboveOrBelow - true if the Instruction either dominates or is dominated
+    // by the current context block or instruction
+    bool aboveOrBelow(Instruction *I) {
+      BasicBlock *BB = I->getParent();
+      DomTreeDFS::Node *Node = DTDFS->getNodeForBlock(BB);
+      if (!Node) return false;
 
-    // below - true if the Instruction is dominated by the current context
-    // block or instruction
-    bool below(Instruction *I) {
-      if (TopInst)
-        return IdomI(TopInst, I);
-      else {
-        ETNode *Node = Forest->getNodeForBlock(I->getParent());
-        return Node->DominatedBy(Top);
-      }
+      return Top == Node || Top->dominates(Node) || Node->dominates(Top);
     }
 
     bool makeEqual(Value *V1, Value *V2) {
-      DOUT << "makeEqual(" << *V1 << ", " << *V2 << ")\n";
+      DEBUG(errs() << "makeEqual(" << *V1 << ", " << *V2 << ")\n");
+      DEBUG(errs() << "context is ");
+      DEBUG(if (TopInst) 
+              errs() << "I: " << *TopInst << "\n";
+            else 
+              errs() << "BB: " << TopBB->getName()
+                     << "(" << Top->getDFSNumIn() << ")\n");
+
+      assert(V1->getType() == V2->getType() &&
+             "Can't make two values with different types equal.");
 
       if (V1 == V2) return true;
 
       if (isa<Constant>(V1) && isa<Constant>(V2))
         return false;
 
-      unsigned n1 = IG.getNode(V1, Top), n2 = IG.getNode(V2, Top);
+      unsigned n1 = VN.valueNumber(V1, Top), n2 = VN.valueNumber(V2, Top);
 
       if (n1 && n2) {
         if (n1 == n2) return true;
         if (IG.isRelatedBy(n1, n2, Top, NE)) return false;
       }
 
-      if (n1) assert(V1 == IG.node(n1)->getValue() && "Value isn't canonical.");
-      if (n2) assert(V2 == IG.node(n2)->getValue() && "Value isn't canonical.");
+      if (n1) assert(V1 == VN.value(n1) && "Value isn't canonical.");
+      if (n2) assert(V2 == VN.value(n2) && "Value isn't canonical.");
 
-      if (compare(V2, V1)) { std::swap(V1, V2); std::swap(n1, n2); }
+      assert(!VN.compare(V2, V1) && "Please order parameters to makeEqual.");
 
       assert(!isa<Constant>(V2) && "Tried to remove a constant.");
 
@@ -881,19 +1423,18 @@ namespace {
         // be EQ and that's invalid. What we're doing is looking for any nodes
         // %z such that %x <= %z and %y >= %z, and vice versa.
 
-        Node *N1 = IG.node(n1);
-        Node *N2 = IG.node(n2);
-        Node::iterator end = N2->end();
+        Node::iterator end = IG.node(n2)->end();
 
         // Find the intersection between N1 and N2 which is dominated by
         // Top. If we find %x where N1 <= %x <= N2 (or >=) then add %x to
         // Remove.
-        for (Node::iterator I = N1->begin(), E = N1->end(); I != E; ++I) {
+        for (Node::iterator I = IG.node(n1)->begin(), E = IG.node(n1)->end();
+             I != E; ++I) {
           if (!(I->LV & EQ_BIT) || !Top->DominatedBy(I->Subtree)) continue;
 
           unsigned ILV_s = I->LV & (SLT_BIT|SGT_BIT);
           unsigned ILV_u = I->LV & (ULT_BIT|UGT_BIT);
-          Node::iterator NI = N2->find(I->To, Top);
+          Node::iterator NI = IG.node(n2)->find(I->To, Top);
           if (NI != end) {
             LatticeVal NILV = reversePredicate(NI->LV);
             unsigned NILV_s = NILV & (SLT_BIT|SGT_BIT);
@@ -912,8 +1453,8 @@ namespace {
         for (SetVector<unsigned>::iterator I = Remove.begin()+1 /* skip n2 */,
              E = Remove.end(); I != E; ++I) {
           unsigned n = *I;
-          Value *V = IG.node(n)->getValue();
-          if (compare(V, V1)) {
+          Value *V = VN.value(n);
+          if (VN.compare(V, V1)) {
             V1 = V;
             n1 = n;
             DontRemove = I;
@@ -927,30 +1468,30 @@ namespace {
       }
 
       // We'd like to allow makeEqual on two values to perform a simple
-      // substitution without every creating nodes in the IG whenever possible.
+      // substitution without creating nodes in the IG whenever possible.
       //
       // The first iteration through this loop operates on V2 before going
       // through the Remove list and operating on those too. If all of the
       // iterations performed simple replacements then we exit early.
-      bool exitEarly = true;
+      bool mergeIGNode = false;
       unsigned i = 0;
       for (Value *R = V2; i == 0 || i < Remove.size(); ++i) {
-        if (i) R = IG.node(Remove[i])->getValue(); // skip n2.
+        if (i) R = VN.value(Remove[i]); // skip n2.
 
         // Try to replace the whole instruction. If we can, we're done.
         Instruction *I2 = dyn_cast<Instruction>(R);
         if (I2 && below(I2)) {
           std::vector<Instruction *> ToNotify;
-          for (Value::use_iterator UI = R->use_begin(), UE = R->use_end();
+          for (Value::use_iterator UI = I2->use_begin(), UE = I2->use_end();
                UI != UE;) {
             Use &TheUse = UI.getUse();
             ++UI;
-            if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser()))
-              ToNotify.push_back(I);
+            Instruction *I = cast<Instruction>(TheUse.getUser());
+            ToNotify.push_back(I);
           }
 
-          DOUT << "Simply removing " << *I2
-               << ", replacing with " << *V1 << "\n";
+          DEBUG(errs() << "Simply removing " << *I2
+                       << ", replacing with " << *V1 << "\n");
           I2->replaceAllUsesWith(V1);
           // leave it dead; it'll get erased later.
           ++NumInstruction;
@@ -981,78 +1522,102 @@ namespace {
 
         // If that killed the instruction, stop here.
         if (I2 && isInstructionTriviallyDead(I2)) {
-          DOUT << "Killed all uses of " << *I2
-               << ", replacing with " << *V1 << "\n";
+          DEBUG(errs() << "Killed all uses of " << *I2
+                       << ", replacing with " << *V1 << "\n");
           continue;
         }
 
         // If we make it to here, then we will need to create a node for N1.
         // Otherwise, we can skip out early!
-        exitEarly = false;
+        mergeIGNode = true;
       }
 
-      if (exitEarly) return true;
+      if (!isa<Constant>(V1)) {
+        if (Remove.empty()) {
+          VR.mergeInto(&V2, 1, VN.getOrInsertVN(V1, Top), Top, this);
+        } else {
+          std::vector<Value*> RemoveVals;
+          RemoveVals.reserve(Remove.size());
+
+          for (SetVector<unsigned>::iterator I = Remove.begin(),
+               E = Remove.end(); I != E; ++I) {
+            Value *V = VN.value(*I);
+            if (!V->use_empty())
+              RemoveVals.push_back(V);
+          }
+          VR.mergeInto(&RemoveVals[0], RemoveVals.size(), 
+                       VN.getOrInsertVN(V1, Top), Top, this);
+        }
+      }
 
-      // Create N1.
-      // XXX: this should call newNode, but instead the node might be created
-      // in isRelatedBy. That's also a fixme.
-      if (!n1) {
-        n1 = IG.getOrInsertNode(V1, Top);
+      if (mergeIGNode) {
+        // Create N1.
+        if (!n1) n1 = VN.getOrInsertVN(V1, Top);
+        IG.node(n1); // Ensure that IG.Nodes won't get resized
 
-        if (isa<ConstantInt>(V1))
-          if (IG.isRelatedBy(n1, n2, Top, NE)) return false;
-      }
+        // Migrate relationships from removed nodes to N1.
+        for (SetVector<unsigned>::iterator I = Remove.begin(), E = Remove.end();
+             I != E; ++I) {
+          unsigned n = *I;
+          for (Node::iterator NI = IG.node(n)->begin(), NE = IG.node(n)->end();
+               NI != NE; ++NI) {
+            if (NI->Subtree->DominatedBy(Top)) {
+              if (NI->To == n1) {
+                assert((NI->LV & EQ_BIT) && "Node inequal to itself.");
+                continue;
+              }
+              if (Remove.count(NI->To))
+                continue;
 
-      // Migrate relationships from removed nodes to N1.
-      Node *N1 = IG.node(n1);
-      for (SetVector<unsigned>::iterator I = Remove.begin(), E = Remove.end();
-           I != E; ++I) {
-        unsigned n = *I;
-        Node *N = IG.node(n);
-        for (Node::iterator NI = N->begin(), NE = N->end(); NI != NE; ++NI) {
-          if (NI->Subtree->DominatedBy(Top)) {
-            if (NI->To == n1) {
-              assert((NI->LV & EQ_BIT) && "Node inequal to itself.");
-              continue;
+              IG.node(NI->To)->update(n1, reversePredicate(NI->LV), Top);
+              IG.node(n1)->update(NI->To, NI->LV, Top);
             }
-            if (Remove.count(NI->To))
-              continue;
-
-            IG.node(NI->To)->update(n1, reversePredicate(NI->LV), Top);
-            N1->update(NI->To, NI->LV, Top);
           }
         }
-      }
 
-      // Point V2 (and all items in Remove) to N1.
-      if (!n2)
-        IG.addEquality(n1, V2, Top);
-      else {
-        for (SetVector<unsigned>::iterator I = Remove.begin(),
-             E = Remove.end(); I != E; ++I) {
-          IG.addEquality(n1, IG.node(*I)->getValue(), Top);
+        // Point V2 (and all items in Remove) to N1.
+        if (!n2)
+          VN.addEquality(n1, V2, Top);
+        else {
+          for (SetVector<unsigned>::iterator I = Remove.begin(),
+               E = Remove.end(); I != E; ++I) {
+            VN.addEquality(n1, VN.value(*I), Top);
+          }
         }
-      }
 
-      // If !Remove.empty() then V2 = Remove[0]->getValue().
-      // Even when Remove is empty, we still want to process V2.
-      i = 0;
-      for (Value *R = V2; i == 0 || i < Remove.size(); ++i) {
-        if (i) R = IG.node(Remove[i])->getValue(); // skip n2.
+        // If !Remove.empty() then V2 = Remove[0]->getValue().
+        // Even when Remove is empty, we still want to process V2.
+        i = 0;
+        for (Value *R = V2; i == 0 || i < Remove.size(); ++i) {
+          if (i) R = VN.value(Remove[i]); // skip n2.
 
-        if (Instruction *I2 = dyn_cast<Instruction>(R)) {
-          if (below(I2) ||
-              Top->DominatedBy(Forest->getNodeForBlock(I2->getParent())))
-          defToOps(I2);
+          if (Instruction *I2 = dyn_cast<Instruction>(R)) {
+            if (aboveOrBelow(I2))
+            defToOps(I2);
+          }
+          for (Value::use_iterator UI = V2->use_begin(), UE = V2->use_end();
+               UI != UE;) {
+            Use &TheUse = UI.getUse();
+            ++UI;
+            if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
+              if (aboveOrBelow(I))
+                opsToDef(I);
+            }
+          }
         }
-        for (Value::use_iterator UI = V2->use_begin(), UE = V2->use_end();
+      }
+
+      // re-opsToDef all dominated users of V1.
+      if (Instruction *I = dyn_cast<Instruction>(V1)) {
+        for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
              UI != UE;) {
           Use &TheUse = UI.getUse();
           ++UI;
-          if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
-            if (below(I) ||
-                Top->DominatedBy(Forest->getNodeForBlock(I->getParent())))
-              opsToDef(I);
+          Value *V = TheUse.getUser();
+          if (!V->use_empty()) {
+            Instruction *Inst = cast<Instruction>(V);
+            if (aboveOrBelow(Inst))
+              opsToDef(Inst);
           }
         }
       }
@@ -1091,61 +1656,88 @@ namespace {
     }
 
   public:
-    VRPSolver(InequalityGraph &IG, UnreachableBlocks &UB, ETForest *Forest,
-              bool &modified, BasicBlock *TopBB)
-      : IG(IG),
+    VRPSolver(ValueNumbering &VN, InequalityGraph &IG, UnreachableBlocks &UB,
+              ValueRanges &VR, DomTreeDFS *DTDFS, bool &modified,
+              BasicBlock *TopBB)
+      : VN(VN),
+        IG(IG),
         UB(UB),
-        Forest(Forest),
-        Top(Forest->getNodeForBlock(TopBB)),
+        VR(VR),
+        DTDFS(DTDFS),
+        Top(DTDFS->getNodeForBlock(TopBB)),
         TopBB(TopBB),
         TopInst(NULL),
-        modified(modified) {}
+        modified(modified),
+        Context(&TopBB->getContext())
+    {
+      assert(Top && "VRPSolver created for unreachable basic block.");
+    }
 
-    VRPSolver(InequalityGraph &IG, UnreachableBlocks &UB, ETForest *Forest,
-              bool &modified, Instruction *TopInst)
-      : IG(IG),
+    VRPSolver(ValueNumbering &VN, InequalityGraph &IG, UnreachableBlocks &UB,
+              ValueRanges &VR, DomTreeDFS *DTDFS, bool &modified,
+              Instruction *TopInst)
+      : VN(VN),
+        IG(IG),
         UB(UB),
-        Forest(Forest),
+        VR(VR),
+        DTDFS(DTDFS),
+        Top(DTDFS->getNodeForBlock(TopInst->getParent())),
+        TopBB(TopInst->getParent()),
         TopInst(TopInst),
-        modified(modified)
+        modified(modified),
+        Context(&TopInst->getContext())
     {
-      TopBB = TopInst->getParent();
-      Top = Forest->getNodeForBlock(TopBB);
+      assert(Top && "VRPSolver created for unreachable basic block.");
+      assert(Top->getBlock() == TopInst->getParent() && "Context mismatch.");
     }
 
     bool isRelatedBy(Value *V1, Value *V2, ICmpInst::Predicate Pred) const {
       if (Constant *C1 = dyn_cast<Constant>(V1))
         if (Constant *C2 = dyn_cast<Constant>(V2))
           return ConstantExpr::getCompare(Pred, C1, C2) ==
-                 ConstantInt::getTrue();
-
-      // XXX: this is lousy. If we're passed a Constant, then we might miss
-      // some relationships if it isn't in the IG because the relationships
-      // added by initializeConstant are missing.
-      if (isa<Constant>(V1)) IG.getOrInsertNode(V1, Top);
-      if (isa<Constant>(V2)) IG.getOrInsertNode(V2, Top);
-
-      if (unsigned n1 = IG.getNode(V1, Top))
-        if (unsigned n2 = IG.getNode(V2, Top)) {
-          if (n1 == n2) return Pred == ICmpInst::ICMP_EQ ||
-                               Pred == ICmpInst::ICMP_ULE ||
-                               Pred == ICmpInst::ICMP_UGE ||
-                               Pred == ICmpInst::ICMP_SLE ||
-                               Pred == ICmpInst::ICMP_SGE;
-          if (Pred == ICmpInst::ICMP_EQ) return false;
-          return IG.isRelatedBy(n1, n2, Top, cmpInstToLattice(Pred));
-        }
+                 ConstantInt::getTrue(*Context);
+
+      unsigned n1 = VN.valueNumber(V1, Top);
+      unsigned n2 = VN.valueNumber(V2, Top);
+
+      if (n1 && n2) {
+        if (n1 == n2) return Pred == ICmpInst::ICMP_EQ ||
+                             Pred == ICmpInst::ICMP_ULE ||
+                             Pred == ICmpInst::ICMP_UGE ||
+                             Pred == ICmpInst::ICMP_SLE ||
+                             Pred == ICmpInst::ICMP_SGE;
+        if (Pred == ICmpInst::ICMP_EQ) return false;
+        if (IG.isRelatedBy(n1, n2, Top, cmpInstToLattice(Pred))) return true;
+        if (VR.isRelatedBy(n1, n2, Top, cmpInstToLattice(Pred))) return true;
+      }
+
+      if ((n1 && !n2 && isa<Constant>(V2)) ||
+          (n2 && !n1 && isa<Constant>(V1))) {
+        ConstantRange CR1 = n1 ? VR.range(n1, Top) : VR.range(V1);
+        ConstantRange CR2 = n2 ? VR.range(n2, Top) : VR.range(V2);
 
+        if (Pred == ICmpInst::ICMP_EQ)
+          return CR1.isSingleElement() &&
+                 CR1.getSingleElement() == CR2.getSingleElement();
+
+        return VR.isRelatedBy(CR1, CR2, cmpInstToLattice(Pred));
+      }
+      if (Pred == ICmpInst::ICMP_EQ) return V1 == V2;
       return false;
     }
 
     /// add - adds a new property to the work queue
     void add(Value *V1, Value *V2, ICmpInst::Predicate Pred,
              Instruction *I = NULL) {
-      DOUT << "adding " << *V1 << " " << Pred << " " << *V2;
-      if (I) DOUT << " context: " << *I;
-      else DOUT << " default context";
-      DOUT << "\n";
+      DEBUG(errs() << "adding " << *V1 << " " << Pred << " " << *V2);
+      if (I)
+        DEBUG(errs() << " context: " << *I);
+      else 
+        DEBUG(errs() << " default context (" << Top->getDFSNumIn() << ")");
+      DEBUG(errs() << "\n");
+
+      assert(V1->getType() == V2->getType() &&
+             "Can't relate two values with different types.");
 
       WorkList.push_back(Operation());
       Operation &O = WorkList.back();
@@ -1157,30 +1749,28 @@ namespace {
     /// new about, find any new relationships between its operands.
     void defToOps(Instruction *I) {
       Instruction *NewContext = below(I) ? I : TopInst;
-      Value *Canonical = IG.canonicalize(I, Top);
+      Value *Canonical = VN.canonicalize(I, Top);
 
       if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
         const Type *Ty = BO->getType();
         assert(!Ty->isFPOrFPVector() && "Float in work queue!");
 
-        Value *Op0 = IG.canonicalize(BO->getOperand(0), Top);
-        Value *Op1 = IG.canonicalize(BO->getOperand(1), Top);
+        Value *Op0 = VN.canonicalize(BO->getOperand(0), Top);
+        Value *Op1 = VN.canonicalize(BO->getOperand(1), Top);
 
-        // TODO: "and bool true, %x" EQ %y then %x EQ %y.
+        // TODO: "and i32 -1, %x" EQ %y then %x EQ %y.
 
         switch (BO->getOpcode()) {
           case Instruction::And: {
-            // "and int %a, %b"  EQ -1   then %a EQ -1   and %b EQ -1
-            // "and bool %a, %b" EQ true then %a EQ true and %b EQ true
-            ConstantInt *CI = ConstantInt::getAllOnesValue(Ty);
+            // "and i32 %a, %b" EQ -1 then %a EQ -1 and %b EQ -1
+            ConstantInt *CI = cast<ConstantInt>(Constant::getAllOnesValue(Ty));
             if (Canonical == CI) {
               add(CI, Op0, ICmpInst::ICMP_EQ, NewContext);
               add(CI, Op1, ICmpInst::ICMP_EQ, NewContext);
             }
           } break;
           case Instruction::Or: {
-            // "or int %a, %b"  EQ 0     then %a EQ 0     and %b EQ 0
-            // "or bool %a, %b" EQ false then %a EQ false and %b EQ false
+            // "or i32 %a, %b" EQ 0 then %a EQ 0 and %b EQ 0
             Constant *Zero = Constant::getNullValue(Ty);
             if (Canonical == Zero) {
               add(Zero, Op0, ICmpInst::ICMP_EQ, NewContext);
@@ -1188,21 +1778,18 @@ namespace {
             }
           } break;
           case Instruction::Xor: {
-            // "xor bool true,  %a" EQ true  then %a EQ false
-            // "xor bool true,  %a" EQ false then %a EQ true
-            // "xor bool false, %a" EQ true  then %a EQ true
-            // "xor bool false, %a" EQ false then %a EQ false
-            // "xor int %c, %a" EQ %c then %a EQ 0
-            // "xor int %c, %a" NE %c then %a NE 0
-            // 1. Repeat all of the above, with order of operands reversed.
+            // "xor i32 %c, %a" EQ %b then %a EQ %c ^ %b
+            // "xor i32 %c, %a" EQ %c then %a EQ 0
+            // "xor i32 %c, %a" NE %c then %a NE 0
+            // Repeat the above, with order of operands reversed.
             Value *LHS = Op0;
             Value *RHS = Op1;
             if (!isa<Constant>(LHS)) std::swap(LHS, RHS);
 
             if (ConstantInt *CI = dyn_cast<ConstantInt>(Canonical)) {
               if (ConstantInt *Arg = dyn_cast<ConstantInt>(LHS)) {
-                add(RHS, ConstantInt::get(CI->getType(), CI->getZExtValue() ^
-                                          Arg->getZExtValue()),
+                add(RHS,
+                  ConstantInt::get(*Context, CI->getValue() ^ Arg->getValue()),
                     ICmpInst::ICMP_EQ, NewContext);
               }
             }
@@ -1219,48 +1806,83 @@ namespace {
             break;
         }
       } else if (ICmpInst *IC = dyn_cast<ICmpInst>(I)) {
-        // "icmp ult int %a, int %y" EQ true then %a u< y
+        // "icmp ult i32 %a, %y" EQ true then %a u< y
         // etc.
 
-        if (Canonical == ConstantInt::getTrue()) {
+        if (Canonical == ConstantInt::getTrue(*Context)) {
           add(IC->getOperand(0), IC->getOperand(1), IC->getPredicate(),
               NewContext);
-        } else if (Canonical == ConstantInt::getFalse()) {
+        } else if (Canonical == ConstantInt::getFalse(*Context)) {
           add(IC->getOperand(0), IC->getOperand(1),
               ICmpInst::getInversePredicate(IC->getPredicate()), NewContext);
         }
       } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
         if (I->getType()->isFPOrFPVector()) return;
 
-        // Given: "%a = select bool %x, int %b, int %c"
+        // Given: "%a = select i1 %x, i32 %b, i32 %c"
         // %a EQ %b and %b NE %c then %x EQ true
         // %a EQ %c and %b NE %c then %x EQ false
 
         Value *True  = SI->getTrueValue();
         Value *False = SI->getFalseValue();
         if (isRelatedBy(True, False, ICmpInst::ICMP_NE)) {
-          if (Canonical == IG.canonicalize(True, Top) ||
+          if (Canonical == VN.canonicalize(True, Top) ||
               isRelatedBy(Canonical, False, ICmpInst::ICMP_NE))
-            add(SI->getCondition(), ConstantInt::getTrue(),
+            add(SI->getCondition(), ConstantInt::getTrue(*Context),
                 ICmpInst::ICMP_EQ, NewContext);
-          else if (Canonical == IG.canonicalize(False, Top) ||
-                   isRelatedBy(I, True, ICmpInst::ICMP_NE))
-            add(SI->getCondition(), ConstantInt::getFalse(),
+          else if (Canonical == VN.canonicalize(False, Top) ||
+                   isRelatedBy(Canonical, True, ICmpInst::ICMP_NE))
+            add(SI->getCondition(), ConstantInt::getFalse(*Context),
                 ICmpInst::ICMP_EQ, NewContext);
         }
+      } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
+        for (GetElementPtrInst::op_iterator OI = GEPI->idx_begin(),
+             OE = GEPI->idx_end(); OI != OE; ++OI) {
+          ConstantInt *Op = dyn_cast<ConstantInt>(VN.canonicalize(*OI, Top));
+          if (!Op || !Op->isZero()) return;
+        }
+        // TODO: The GEPI indices are all zero. Copy from definition to operand,
+        // jumping the type plane as needed.
+        if (isRelatedBy(GEPI, Constant::getNullValue(GEPI->getType()),
+                        ICmpInst::ICMP_NE)) {
+          Value *Ptr = GEPI->getPointerOperand();
+          add(Ptr, Constant::getNullValue(Ptr->getType()), ICmpInst::ICMP_NE,
+              NewContext);
+        }
+      } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
+        const Type *SrcTy = CI->getSrcTy();
+
+        unsigned ci = VN.getOrInsertVN(CI, Top);
+        uint32_t W = VR.typeToWidth(SrcTy);
+        if (!W) return;
+        ConstantRange CR = VR.range(ci, Top);
+
+        if (CR.isFullSet()) return;
+
+        switch (CI->getOpcode()) {
+          default: break;
+          case Instruction::ZExt:
+          case Instruction::SExt:
+            VR.applyRange(VN.getOrInsertVN(CI->getOperand(0), Top),
+                          CR.truncate(W), Top, this);
+            break;
+          case Instruction::BitCast:
+            VR.applyRange(VN.getOrInsertVN(CI->getOperand(0), Top),
+                          CR, Top, this);
+            break;
+        }
       }
-      // TODO: CastInst "%a = cast ... %b" where %a is EQ or NE a constant.
     }
 
     /// opsToDef - A new relationship was discovered involving one of this
     /// instruction's operands. Find any new relationship involving the
-    /// definition.
+    /// definition, or another operand.
     void opsToDef(Instruction *I) {
       Instruction *NewContext = below(I) ? I : TopInst;
 
       if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
-        Value *Op0 = IG.canonicalize(BO->getOperand(0), Top);
-        Value *Op1 = IG.canonicalize(BO->getOperand(1), Top);
+        Value *Op0 = VN.canonicalize(BO->getOperand(0), Top);
+        Value *Op1 = VN.canonicalize(BO->getOperand(1), Top);
 
         if (ConstantInt *CI0 = dyn_cast<ConstantInt>(Op0))
           if (ConstantInt *CI1 = dyn_cast<ConstantInt>(Op1)) {
@@ -1269,160 +1891,311 @@ namespace {
             return;
           }
 
-        // "%y = and bool true, %x" then %x EQ %y.
-        // "%y = or bool false, %x" then %x EQ %y.
-        if (BO->getOpcode() == Instruction::Or) {
-          Constant *Zero = Constant::getNullValue(BO->getType());
-          if (Op0 == Zero) {
-            add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
-            return;
-          } else if (Op1 == Zero) {
-            add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
-            return;
-          }
-        } else if (BO->getOpcode() == Instruction::And) {
-          Constant *AllOnes = ConstantInt::getAllOnesValue(BO->getType());
-          if (Op0 == AllOnes) {
-            add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
-            return;
-          } else if (Op1 == AllOnes) {
-            add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
-            return;
-          }
-        }
+        // "%y = and i1 true, %x" then %x EQ %y
+        // "%y = or i1 false, %x" then %x EQ %y
+        // "%x = add i32 %y, 0" then %x EQ %y
+        // "%x = mul i32 %y, 0" then %x EQ 0
+
+        Instruction::BinaryOps Opcode = BO->getOpcode();
+        const Type *Ty = BO->getType();
+        assert(!Ty->isFPOrFPVector() && "Float in work queue!");
 
-        // "%x = add int %y, %z" and %x EQ %y then %z EQ 0
-        // "%x = mul int %y, %z" and %x EQ %y then %z EQ 1
-        // 1. Repeat all of the above, with order of operands reversed.
-        // "%x = udiv int %y, %z" and %x EQ %y then %z EQ 1
+        Constant *Zero = Constant::getNullValue(Ty);
+        Constant *One = ConstantInt::get(Ty, 1);
+        ConstantInt *AllOnes = cast<ConstantInt>(Constant::getAllOnesValue(Ty));
+
+        switch (Opcode) {
+          default: break;
+          case Instruction::LShr:
+          case Instruction::AShr:
+          case Instruction::Shl:
+            if (Op1 == Zero) {
+              add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            break;
+          case Instruction::Sub:
+            if (Op1 == Zero) {
+              add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            if (ConstantInt *CI0 = dyn_cast<ConstantInt>(Op0)) {
+              unsigned n_ci0 = VN.getOrInsertVN(Op1, Top);
+              ConstantRange CR = VR.range(n_ci0, Top);
+              if (!CR.isFullSet()) {
+                CR.subtract(CI0->getValue());
+                unsigned n_bo = VN.getOrInsertVN(BO, Top);
+                VR.applyRange(n_bo, CR, Top, this);
+                return;
+              }
+            }
+            if (ConstantInt *CI1 = dyn_cast<ConstantInt>(Op1)) {
+              unsigned n_ci1 = VN.getOrInsertVN(Op0, Top);
+              ConstantRange CR = VR.range(n_ci1, Top);
+              if (!CR.isFullSet()) {
+                CR.subtract(CI1->getValue());
+                unsigned n_bo = VN.getOrInsertVN(BO, Top);
+                VR.applyRange(n_bo, CR, Top, this);
+                return;
+              }
+            }
+            break;
+          case Instruction::Or:
+            if (Op0 == AllOnes || Op1 == AllOnes) {
+              add(BO, AllOnes, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            if (Op0 == Zero) {
+              add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            } else if (Op1 == Zero) {
+              add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            break;
+          case Instruction::Add:
+            if (ConstantInt *CI0 = dyn_cast<ConstantInt>(Op0)) {
+              unsigned n_ci0 = VN.getOrInsertVN(Op1, Top);
+              ConstantRange CR = VR.range(n_ci0, Top);
+              if (!CR.isFullSet()) {
+                CR.subtract(-CI0->getValue());
+                unsigned n_bo = VN.getOrInsertVN(BO, Top);
+                VR.applyRange(n_bo, CR, Top, this);
+                return;
+              }
+            }
+            if (ConstantInt *CI1 = dyn_cast<ConstantInt>(Op1)) {
+              unsigned n_ci1 = VN.getOrInsertVN(Op0, Top);
+              ConstantRange CR = VR.range(n_ci1, Top);
+              if (!CR.isFullSet()) {
+                CR.subtract(-CI1->getValue());
+                unsigned n_bo = VN.getOrInsertVN(BO, Top);
+                VR.applyRange(n_bo, CR, Top, this);
+                return;
+              }
+            }
+            // fall-through
+          case Instruction::Xor:
+            if (Op0 == Zero) {
+              add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            } else if (Op1 == Zero) {
+              add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            break;
+          case Instruction::And:
+            if (Op0 == AllOnes) {
+              add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            } else if (Op1 == AllOnes) {
+              add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            if (Op0 == Zero || Op1 == Zero) {
+              add(BO, Zero, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            break;
+          case Instruction::Mul:
+            if (Op0 == Zero || Op1 == Zero) {
+              add(BO, Zero, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            if (Op0 == One) {
+              add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            } else if (Op1 == One) {
+              add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
+              return;
+            }
+            break;
+        }
 
-        Value *Known = Op0, *Unknown = Op1;
-        if (Known != BO) std::swap(Known, Unknown);
-        if (Known == BO) {
-          const Type *Ty = BO->getType();
-          assert(!Ty->isFPOrFPVector() && "Float in work queue!");
+        // "%x = add i32 %y, %z" and %x EQ %y then %z EQ 0
+        // "%x = add i32 %y, %z" and %x EQ %z then %y EQ 0
+        // "%x = shl i32 %y, %z" and %x EQ %y and %y NE 0 then %z EQ 0
+        // "%x = udiv i32 %y, %z" and %x EQ %y and %y NE 0 then %z EQ 1
 
-          switch (BO->getOpcode()) {
+        Value *Known = Op0, *Unknown = Op1,
+              *TheBO = VN.canonicalize(BO, Top);
+        if (Known != TheBO) std::swap(Known, Unknown);
+        if (Known == TheBO) {
+          switch (Opcode) {
             default: break;
+            case Instruction::LShr:
+            case Instruction::AShr:
+            case Instruction::Shl:
+              if (!isRelatedBy(Known, Zero, ICmpInst::ICMP_NE)) break;
+              // otherwise, fall-through.
+            case Instruction::Sub:
+              if (Unknown == Op0) break;
+              // otherwise, fall-through.
             case Instruction::Xor:
-            case Instruction::Or:
             case Instruction::Add:
-            case Instruction::Sub:
-              add(Unknown, Constant::getNullValue(Ty), ICmpInst::ICMP_EQ,
-                  NewContext);
+              add(Unknown, Zero, ICmpInst::ICMP_EQ, NewContext);
               break;
             case Instruction::UDiv:
             case Instruction::SDiv:
-              if (Unknown == Op0) break; // otherwise, fallthrough
-            case Instruction::And:
-            case Instruction::Mul:
-              if (isa<ConstantInt>(Unknown)) {
-                Constant *One = ConstantInt::get(Ty, 1);
+              if (Unknown == Op1) break;
+              if (isRelatedBy(Known, Zero, ICmpInst::ICMP_NE))
                 add(Unknown, One, ICmpInst::ICMP_EQ, NewContext);
-              }
               break;
           }
         }
 
-        // TODO: "%a = add int %b, 1" and %b > %z then %a >= %z.
+        // TODO: "%a = add i32 %b, 1" and %b > %z then %a >= %z.
 
       } else if (ICmpInst *IC = dyn_cast<ICmpInst>(I)) {
-        // "%a = icmp ult %b, %c" and %b u< %c  then %a EQ true
-        // "%a = icmp ult %b, %c" and %b u>= %c then %a EQ false
+        // "%a = icmp ult i32 %b, %c" and %b u<  %c then %a EQ true
+        // "%a = icmp ult i32 %b, %c" and %b u>= %c then %a EQ false
         // etc.
 
-        Value *Op0 = IG.canonicalize(IC->getOperand(0), Top);
-        Value *Op1 = IG.canonicalize(IC->getOperand(1), Top);
+        Value *Op0 = VN.canonicalize(IC->getOperand(0), Top);
+        Value *Op1 = VN.canonicalize(IC->getOperand(1), Top);
 
         ICmpInst::Predicate Pred = IC->getPredicate();
-        if (isRelatedBy(Op0, Op1, Pred)) {
-          add(IC, ConstantInt::getTrue(), ICmpInst::ICMP_EQ, NewContext);
-        } else if (isRelatedBy(Op0, Op1, ICmpInst::getInversePredicate(Pred))) {
-          add(IC, ConstantInt::getFalse(), ICmpInst::ICMP_EQ, NewContext);
-        }
-
-        // TODO: "bool %x s<u> %y" implies %x = true and %y = false.
-
-        // TODO: make the predicate more strict, if possible.
+        if (isRelatedBy(Op0, Op1, Pred))
+          add(IC, ConstantInt::getTrue(*Context), ICmpInst::ICMP_EQ, NewContext);
+        else if (isRelatedBy(Op0, Op1, ICmpInst::getInversePredicate(Pred)))
+          add(IC, ConstantInt::getFalse(*Context),
+              ICmpInst::ICMP_EQ, NewContext);
 
       } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
-        // Given: "%a = select bool %x, int %b, int %c"
+        if (I->getType()->isFPOrFPVector()) return;
+
+        // Given: "%a = select i1 %x, i32 %b, i32 %c"
         // %x EQ true  then %a EQ %b
         // %x EQ false then %a EQ %c
         // %b EQ %c then %a EQ %b
 
-        Value *Canonical = IG.canonicalize(SI->getCondition(), Top);
-        if (Canonical == ConstantInt::getTrue()) {
+        Value *Canonical = VN.canonicalize(SI->getCondition(), Top);
+        if (Canonical == ConstantInt::getTrue(*Context)) {
           add(SI, SI->getTrueValue(), ICmpInst::ICMP_EQ, NewContext);
-        } else if (Canonical == ConstantInt::getFalse()) {
+        } else if (Canonical == ConstantInt::getFalse(*Context)) {
           add(SI, SI->getFalseValue(), ICmpInst::ICMP_EQ, NewContext);
-        } else if (IG.canonicalize(SI->getTrueValue(), Top) ==
-                   IG.canonicalize(SI->getFalseValue(), Top)) {
+        } else if (VN.canonicalize(SI->getTrueValue(), Top) ==
+                   VN.canonicalize(SI->getFalseValue(), Top)) {
           add(SI, SI->getTrueValue(), ICmpInst::ICMP_EQ, NewContext);
         }
       } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
-        if (CI->getDestTy()->isFPOrFPVector()) return;
+        const Type *DestTy = CI->getDestTy();
+        if (DestTy->isFPOrFPVector()) return;
 
-        if (Constant *C = dyn_cast<Constant>(
-                IG.canonicalize(CI->getOperand(0), Top))) {
-          add(CI, ConstantExpr::getCast(CI->getOpcode(), C, CI->getDestTy()),
+        Value *Op = VN.canonicalize(CI->getOperand(0), Top);
+        Instruction::CastOps Opcode = CI->getOpcode();
+
+        if (Constant *C = dyn_cast<Constant>(Op)) {
+          add(CI, ConstantExpr::getCast(Opcode, C, DestTy),
               ICmpInst::ICMP_EQ, NewContext);
         }
 
-        // TODO: "%a = cast ... %b" where %b is NE/LT/GT a constant.
+        uint32_t W = VR.typeToWidth(DestTy);
+        unsigned ci = VN.getOrInsertVN(CI, Top);
+        ConstantRange CR = VR.range(VN.getOrInsertVN(Op, Top), Top);
+
+        if (!CR.isFullSet()) {
+          switch (Opcode) {
+            default: break;
+            case Instruction::ZExt:
+              VR.applyRange(ci, CR.zeroExtend(W), Top, this);
+              break;
+            case Instruction::SExt:
+              VR.applyRange(ci, CR.signExtend(W), Top, this);
+              break;
+            case Instruction::Trunc: {
+              ConstantRange Result = CR.truncate(W);
+              if (!Result.isFullSet())
+                VR.applyRange(ci, Result, Top, this);
+            } break;
+            case Instruction::BitCast:
+              VR.applyRange(ci, CR, Top, this);
+              break;
+            // TODO: other casts?
+          }
+        }
+      } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
+        for (GetElementPtrInst::op_iterator OI = GEPI->idx_begin(),
+             OE = GEPI->idx_end(); OI != OE; ++OI) {
+          ConstantInt *Op = dyn_cast<ConstantInt>(VN.canonicalize(*OI, Top));
+          if (!Op || !Op->isZero()) return;
+        }
+        // TODO: The GEPI indices are all zero. Copy from operand to definition,
+        // jumping the type plane as needed.
+        Value *Ptr = GEPI->getPointerOperand();
+        if (isRelatedBy(Ptr, Constant::getNullValue(Ptr->getType()),
+                        ICmpInst::ICMP_NE)) {
+          add(GEPI, Constant::getNullValue(GEPI->getType()), ICmpInst::ICMP_NE,
+              NewContext);
+        }
       }
     }
 
     /// solve - process the work queue
-    /// Return false if a logical contradiction occurs.
     void solve() {
-      //DOUT << "WorkList entry, size: " << WorkList.size() << "\n";
+      //DEBUG(errs() << "WorkList entry, size: " << WorkList.size() << "\n");
       while (!WorkList.empty()) {
-        //DOUT << "WorkList size: " << WorkList.size() << "\n";
+        //DEBUG(errs() << "WorkList size: " << WorkList.size() << "\n");
 
         Operation &O = WorkList.front();
         TopInst = O.ContextInst;
         TopBB = O.ContextBB;
-        Top = Forest->getNodeForBlock(TopBB);
-
-        O.LHS = IG.canonicalize(O.LHS, Top);
-        O.RHS = IG.canonicalize(O.RHS, Top);
-
-        assert(O.LHS == IG.canonicalize(O.LHS, Top) && "Canonicalize isn't.");
-        assert(O.RHS == IG.canonicalize(O.RHS, Top) && "Canonicalize isn't.");
-
-        DOUT << "solving " << *O.LHS << " " << O.Op << " " << *O.RHS;
-        if (O.ContextInst) DOUT << " context inst: " << *O.ContextInst;
-        else DOUT << " context block: " << O.ContextBB->getName();
-        DOUT << "\n";
+        Top = DTDFS->getNodeForBlock(TopBB); // XXX move this into Context
+
+        O.LHS = VN.canonicalize(O.LHS, Top);
+        O.RHS = VN.canonicalize(O.RHS, Top);
+
+        assert(O.LHS == VN.canonicalize(O.LHS, Top) && "Canonicalize isn't.");
+        assert(O.RHS == VN.canonicalize(O.RHS, Top) && "Canonicalize isn't.");
+
+        DEBUG(errs() << "solving " << *O.LHS << " " << O.Op << " " << *O.RHS;
+              if (O.ContextInst) 
+                errs() << " context inst: " << *O.ContextInst;
+              else
+                errs() << " context block: " << O.ContextBB->getName();
+              errs() << "\n";
+
+              VN.dump();
+              IG.dump();
+              VR.dump(););
+
+        // If they're both Constant, skip it. Check for contradiction and mark
+        // the BB as unreachable if so.
+        if (Constant *CI_L = dyn_cast<Constant>(O.LHS)) {
+          if (Constant *CI_R = dyn_cast<Constant>(O.RHS)) {
+            if (ConstantExpr::getCompare(O.Op, CI_L, CI_R) ==
+                ConstantInt::getFalse(*Context))
+              UB.mark(TopBB);
 
-        DEBUG(IG.dump());
+            WorkList.pop_front();
+            continue;
+          }
+        }
 
-        // TODO: actually check the constants and add to UB.
-        if (isa<Constant>(O.LHS) && isa<Constant>(O.RHS)) {
-          WorkList.pop_front();
-          continue;
+        if (VN.compare(O.LHS, O.RHS)) {
+          std::swap(O.LHS, O.RHS);
+          O.Op = ICmpInst::getSwappedPredicate(O.Op);
         }
 
         if (O.Op == ICmpInst::ICMP_EQ) {
-          if (!makeEqual(O.LHS, O.RHS))
+          if (!makeEqual(O.RHS, O.LHS))
             UB.mark(TopBB);
         } else {
           LatticeVal LV = cmpInstToLattice(O.Op);
 
           if ((LV & EQ_BIT) &&
               isRelatedBy(O.LHS, O.RHS, ICmpInst::getSwappedPredicate(O.Op))) {
-            if (!makeEqual(O.LHS, O.RHS))
+            if (!makeEqual(O.RHS, O.LHS))
               UB.mark(TopBB);
           } else {
             if (isRelatedBy(O.LHS, O.RHS, ICmpInst::getInversePredicate(O.Op))){
-              DOUT << "inequality contradiction!\n";
+              UB.mark(TopBB);
               WorkList.pop_front();
               continue;
             }
 
-            unsigned n1 = IG.getOrInsertNode(O.LHS, Top);
-            unsigned n2 = IG.getOrInsertNode(O.RHS, Top);
+            unsigned n1 = VN.getOrInsertVN(O.LHS, Top);
+            unsigned n2 = VN.getOrInsertVN(O.RHS, Top);
 
             if (n1 == n2) {
               if (O.Op != ICmpInst::ICMP_UGE && O.Op != ICmpInst::ICMP_ULE &&
@@ -1433,16 +2206,19 @@ namespace {
               continue;
             }
 
-            if (IG.isRelatedBy(n1, n2, Top, LV)) {
+            if (VR.isRelatedBy(n1, n2, Top, LV) ||
+                IG.isRelatedBy(n1, n2, Top, LV)) {
               WorkList.pop_front();
               continue;
             }
 
-            IG.addInequality(n1, n2, Top, LV);
+            VR.addInequality(n1, n2, Top, LV, this);
+            if ((!isa<ConstantInt>(O.RHS) && !isa<ConstantInt>(O.LHS)) ||
+                LV == NE)
+              IG.addInequality(n1, n2, Top, LV);
 
             if (Instruction *I1 = dyn_cast<Instruction>(O.LHS)) {
-              if (below(I1) ||
-                  Top->DominatedBy(Forest->getNodeForBlock(I1->getParent())))
+              if (aboveOrBelow(I1))
                 defToOps(I1);
             }
             if (isa<Instruction>(O.LHS) || isa<Argument>(O.LHS)) {
@@ -1450,16 +2226,13 @@ namespace {
                    UE = O.LHS->use_end(); UI != UE;) {
                 Use &TheUse = UI.getUse();
                 ++UI;
-                if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
-                  if (below(I) ||
-                      Top->DominatedBy(Forest->getNodeForBlock(I->getParent())))
-                    opsToDef(I);
-                }
+                Instruction *I = cast<Instruction>(TheUse.getUser());
+                if (aboveOrBelow(I))
+                  opsToDef(I);
               }
             }
             if (Instruction *I2 = dyn_cast<Instruction>(O.RHS)) {
-              if (below(I2) ||
-                  Top->DominatedBy(Forest->getNodeForBlock(I2->getParent())))
+              if (aboveOrBelow(I2))
               defToOps(I2);
             }
             if (isa<Instruction>(O.RHS) || isa<Argument>(O.RHS)) {
@@ -1467,12 +2240,9 @@ namespace {
                    UE = O.RHS->use_end(); UI != UE;) {
                 Use &TheUse = UI.getUse();
                 ++UI;
-                if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
-                  if (below(I) ||
-                      Top->DominatedBy(Forest->getNodeForBlock(I->getParent())))
-
-                    opsToDef(I);
-                }
+                Instruction *I = cast<Instruction>(TheUse.getUser());
+                if (aboveOrBelow(I))
+                  opsToDef(I);
               }
             }
           }
@@ -1482,46 +2252,62 @@ namespace {
     }
   };
 
+  void ValueRanges::addToWorklist(Value *V, Constant *C,
+                                  ICmpInst::Predicate Pred, VRPSolver *VRP) {
+    VRP->add(V, C, Pred, VRP->TopInst);
+  }
+
+  void ValueRanges::markBlock(VRPSolver *VRP) {
+    VRP->UB.mark(VRP->TopBB);
+  }
+
   /// PredicateSimplifier - This class is a simplifier that replaces
   /// one equivalent variable with another. It also tracks what
   /// can't be equal and will solve setcc instructions when possible.
   /// @brief Root of the predicate simplifier optimization.
-  class VISIBILITY_HIDDEN PredicateSimplifier : public FunctionPass {
-    DominatorTree *DT;
-    ETForest *Forest;
+  class PredicateSimplifier : public FunctionPass {
+    DomTreeDFS *DTDFS;
     bool modified;
+    ValueNumbering *VN;
     InequalityGraph *IG;
     UnreachableBlocks UB;
+    ValueRanges *VR;
 
-    std::vector<DominatorTree::Node *> WorkList;
+    std::vector<DomTreeDFS::Node *> WorkList;
 
+    LLVMContext *Context;
   public:
+    static char ID; // Pass identification, replacement for typeid
+    PredicateSimplifier() : FunctionPass(&ID) {}
+
     bool runOnFunction(Function &F);
 
     virtual void getAnalysisUsage(AnalysisUsage &AU) const {
       AU.addRequiredID(BreakCriticalEdgesID);
       AU.addRequired<DominatorTree>();
-      AU.addRequired<ETForest>();
     }
 
   private:
-    /// Forwards - Adds new properties into PropertySet and uses them to
+    /// Forwards - Adds new properties to VRPSolver and uses them to
     /// simplify instructions. Because new properties sometimes apply to
     /// a transition from one BasicBlock to another, this will use the
     /// PredicateSimplifier::proceedToSuccessor(s) interface to enter the
-    /// basic block with the new PropertySet.
+    /// basic block.
     /// @brief Performs abstract execution of the program.
-    class VISIBILITY_HIDDEN Forwards : public InstVisitor<Forwards> {
+    class Forwards : public InstVisitor<Forwards> {
       friend class InstVisitor<Forwards>;
       PredicateSimplifier *PS;
-      DominatorTree::Node *DTNode;
+      DomTreeDFS::Node *DTNode;
 
     public:
+      ValueNumbering &VN;
       InequalityGraph &IG;
       UnreachableBlocks &UB;
+      ValueRanges &VR;
 
-      Forwards(PredicateSimplifier *PS, DominatorTree::Node *DTNode)
-        : PS(PS), DTNode(DTNode), IG(*PS->IG), UB(PS->UB) {}
+      Forwards(PredicateSimplifier *PS, DomTreeDFS::Node *DTNode)
+        : PS(PS), DTNode(DTNode), VN(*PS->VN), IG(*PS->IG), UB(PS->UB),
+          VR(*PS->VR) {}
 
       void visitTerminatorInst(TerminatorInst &TI);
       void visitBranchInst(BranchInst &BI);
@@ -1531,58 +2317,66 @@ namespace {
       void visitLoadInst(LoadInst &LI);
       void visitStoreInst(StoreInst &SI);
 
+      void visitSExtInst(SExtInst &SI);
+      void visitZExtInst(ZExtInst &ZI);
+
       void visitBinaryOperator(BinaryOperator &BO);
+      void visitICmpInst(ICmpInst &IC);
     };
-
+  
     // Used by terminator instructions to proceed from the current basic
     // block to the next. Verifies that "current" dominates "next",
     // then calls visitBasicBlock.
-    void proceedToSuccessors(DominatorTree::Node *Current) {
-      for (DominatorTree::Node::iterator I = Current->begin(),
+    void proceedToSuccessors(DomTreeDFS::Node *Current) {
+      for (DomTreeDFS::Node::iterator I = Current->begin(),
            E = Current->end(); I != E; ++I) {
         WorkList.push_back(*I);
       }
     }
 
-    void proceedToSuccessor(DominatorTree::Node *Next) {
+    void proceedToSuccessor(DomTreeDFS::Node *Next) {
       WorkList.push_back(Next);
     }
 
     // Visits each instruction in the basic block.
-    void visitBasicBlock(DominatorTree::Node *Node) {
+    void visitBasicBlock(DomTreeDFS::Node *Node) {
       BasicBlock *BB = Node->getBlock();
-      ETNode *ET = Forest->getNodeForBlock(BB);
-      DOUT << "Entering Basic Block: " << BB->getName()
-           << " (" << ET->getDFSNumIn() << ")\n";
+      DEBUG(errs() << "Entering Basic Block: " << BB->getName()
+            << " (" << Node->getDFSNumIn() << ")\n");
       for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
-        visitInstruction(I++, Node, ET);
+        visitInstruction(I++, Node);
       }
     }
 
-    // Tries to simplify each Instruction and add new properties to
-    // the PropertySet.
-    void visitInstruction(Instruction *I, DominatorTree::Node *DT, ETNode *ET) {
-      DOUT << "Considering instruction " << *I << "\n";
+    // Tries to simplify each Instruction and add new properties.
+    void visitInstruction(Instruction *I, DomTreeDFS::Node *DT) {
+      DEBUG(errs() << "Considering instruction " << *I << "\n");
+      DEBUG(VN->dump());
       DEBUG(IG->dump());
+      DEBUG(VR->dump());
 
       // Sometimes instructions are killed in earlier analysis.
       if (isInstructionTriviallyDead(I)) {
         ++NumSimple;
         modified = true;
-        IG->remove(I);
+        if (unsigned n = VN->valueNumber(I, DTDFS->getRootNode()))
+          if (VN->value(n) == I) IG->remove(n);
+        VN->remove(I);
         I->eraseFromParent();
         return;
       }
 
 #ifndef NDEBUG
       // Try to replace the whole instruction.
-      Value *V = IG->canonicalize(I, ET);
+      Value *V = VN->canonicalize(I, DT);
       assert(V == I && "Late instruction canonicalization.");
       if (V != I) {
         modified = true;
         ++NumInstruction;
-        DOUT << "Removing " << *I << ", replacing with " << *V << "\n";
-        IG->remove(I);
+        DEBUG(errs() << "Removing " << *I << ", replacing with " << *V << "\n");
+        if (unsigned n = VN->valueNumber(I, DTDFS->getRootNode()))
+          if (VN->value(n) == I) IG->remove(n);
+        VN->remove(I);
         I->replaceAllUsesWith(V);
         I->eraseFromParent();
         return;
@@ -1591,45 +2385,57 @@ namespace {
       // Try to substitute operands.
       for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
         Value *Oper = I->getOperand(i);
-        Value *V = IG->canonicalize(Oper, ET);
+        Value *V = VN->canonicalize(Oper, DT);
         assert(V == Oper && "Late operand canonicalization.");
         if (V != Oper) {
           modified = true;
           ++NumVarsReplaced;
-          DOUT << "Resolving " << *I;
+          DEBUG(errs() << "Resolving " << *I);
           I->setOperand(i, V);
-          DOUT << " into " << *I;
+          DEBUG(errs() << " into " << *I);
         }
       }
 #endif
 
-      DOUT << "push (%" << I->getParent()->getName() << ")\n";
+      std::string name = I->getParent()->getName();
+      DEBUG(errs() << "push (%" << name << ")\n");
       Forwards visit(this, DT);
       visit.visit(*I);
-      DOUT << "pop (%" << I->getParent()->getName() << ")\n";
+      DEBUG(errs() << "pop (%" << name << ")\n");
     }
   };
 
   bool PredicateSimplifier::runOnFunction(Function &F) {
-    DT = &getAnalysis<DominatorTree>();
-    Forest = &getAnalysis<ETForest>();
+    DominatorTree *DT = &getAnalysis<DominatorTree>();
+    DTDFS = new DomTreeDFS(DT);
+    TargetData *TD = getAnalysisIfAvailable<TargetData>();
 
-    Forest->updateDFSNumbers(); // XXX: should only act when numbers are out of date
+    // FIXME: PredicateSimplifier should still be able to do basic
+    // optimizations without TargetData. But for now, just exit if
+    // it's not available.
+    if (!TD) return false;
 
-    DOUT << "Entering Function: " << F.getName() << "\n";
+    Context = &F.getContext();
+
+    DEBUG(errs() << "Entering Function: " << F.getName() << "\n");
 
     modified = false;
-    BasicBlock *RootBlock = &F.getEntryBlock();
-    IG = new InequalityGraph(Forest->getNodeForBlock(RootBlock));
-    WorkList.push_back(DT->getRootNode());
+    DomTreeDFS::Node *Root = DTDFS->getRootNode();
+    VN = new ValueNumbering(DTDFS);
+    IG = new InequalityGraph(*VN, Root);
+    VR = new ValueRanges(*VN, TD, Context);
+    WorkList.push_back(Root);
 
     do {
-      DominatorTree::Node *DTNode = WorkList.back();
+      DomTreeDFS::Node *DTNode = WorkList.back();
       WorkList.pop_back();
       if (!UB.isDead(DTNode->getBlock())) visitBasicBlock(DTNode);
     } while (!WorkList.empty());
 
+    delete DTDFS;
+    delete VR;
     delete IG;
+    delete VN;
 
     modified |= UB.kill();
 
@@ -1655,24 +2461,32 @@ namespace {
       return;
     }
 
-    for (DominatorTree::Node::iterator I = DTNode->begin(), E = DTNode->end();
+    LLVMContext *Context = &BI.getContext();
+
+    for (DomTreeDFS::Node::iterator I = DTNode->begin(), E = DTNode->end();
          I != E; ++I) {
       BasicBlock *Dest = (*I)->getBlock();
-      DOUT << "Branch thinking about %" << Dest->getName()
-           << "(" << PS->Forest->getNodeForBlock(Dest)->getDFSNumIn() << ")\n";
+      DEBUG(errs() << "Branch thinking about %" << Dest->getName()
+            << "(" << PS->DTDFS->getNodeForBlock(Dest)->getDFSNumIn() << ")\n");
 
       if (Dest == TrueDest) {
-        DOUT << "(" << DTNode->getBlock()->getName() << ") true set:\n";
-        VRPSolver VRP(IG, UB, PS->Forest, PS->modified, Dest);
-        VRP.add(ConstantInt::getTrue(), Condition, ICmpInst::ICMP_EQ);
+        DEBUG(errs() << "(" << DTNode->getBlock()->getName() 
+              << ") true set:\n");
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, Dest);
+        VRP.add(ConstantInt::getTrue(*Context), Condition, ICmpInst::ICMP_EQ);
         VRP.solve();
+        DEBUG(VN.dump());
         DEBUG(IG.dump());
+        DEBUG(VR.dump());
       } else if (Dest == FalseDest) {
-        DOUT << "(" << DTNode->getBlock()->getName() << ") false set:\n";
-        VRPSolver VRP(IG, UB, PS->Forest, PS->modified, Dest);
-        VRP.add(ConstantInt::getFalse(), Condition, ICmpInst::ICMP_EQ);
+        DEBUG(errs() << "(" << DTNode->getBlock()->getName() 
+              << ") false set:\n");
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, Dest);
+        VRP.add(ConstantInt::getFalse(*Context), Condition, ICmpInst::ICMP_EQ);
         VRP.solve();
+        DEBUG(VN.dump());
         DEBUG(IG.dump());
+        DEBUG(VR.dump());
       }
 
       PS->proceedToSuccessor(*I);
@@ -1685,13 +2499,13 @@ namespace {
     // Set the EQProperty in each of the cases BBs, and the NEProperties
     // in the default BB.
 
-    for (DominatorTree::Node::iterator I = DTNode->begin(), E = DTNode->end();
+    for (DomTreeDFS::Node::iterator I = DTNode->begin(), E = DTNode->end();
          I != E; ++I) {
       BasicBlock *BB = (*I)->getBlock();
-      DOUT << "Switch thinking about BB %" << BB->getName()
-           << "(" << PS->Forest->getNodeForBlock(BB)->getDFSNumIn() << ")\n";
+      DEBUG(errs() << "Switch thinking about BB %" << BB->getName()
+            << "(" << PS->DTDFS->getNodeForBlock(BB)->getDFSNumIn() << ")\n");
 
-      VRPSolver VRP(IG, UB, PS->Forest, PS->modified, BB);
+      VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, BB);
       if (BB == SI.getDefaultDest()) {
         for (unsigned i = 1, e = SI.getNumCases(); i < e; ++i)
           if (SI.getSuccessor(i) != BB)
@@ -1706,18 +2520,20 @@ namespace {
   }
 
   void PredicateSimplifier::Forwards::visitAllocaInst(AllocaInst &AI) {
-    VRPSolver VRP(IG, UB, PS->Forest, PS->modified, &AI);
-    VRP.add(Constant::getNullValue(AI.getType()), &AI, ICmpInst::ICMP_NE);
+    VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &AI);
+    VRP.add(Constant::getNullValue(AI.getType()),
+            &AI, ICmpInst::ICMP_NE);
     VRP.solve();
   }
 
   void PredicateSimplifier::Forwards::visitLoadInst(LoadInst &LI) {
     Value *Ptr = LI.getPointerOperand();
-    // avoid "load uint* null" -> null NE null.
+    // avoid "load i8* null" -> null NE null.
     if (isa<Constant>(Ptr)) return;
 
-    VRPSolver VRP(IG, UB, PS->Forest, PS->modified, &LI);
-    VRP.add(Constant::getNullValue(Ptr->getType()), Ptr, ICmpInst::ICMP_NE);
+    VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &LI);
+    VRP.add(Constant::getNullValue(Ptr->getType()),
+            Ptr, ICmpInst::ICMP_NE);
     VRP.solve();
   }
 
@@ -1725,8 +2541,31 @@ namespace {
     Value *Ptr = SI.getPointerOperand();
     if (isa<Constant>(Ptr)) return;
 
-    VRPSolver VRP(IG, UB, PS->Forest, PS->modified, &SI);
-    VRP.add(Constant::getNullValue(Ptr->getType()), Ptr, ICmpInst::ICMP_NE);
+    VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &SI);
+    VRP.add(Constant::getNullValue(Ptr->getType()),
+            Ptr, ICmpInst::ICMP_NE);
+    VRP.solve();
+  }
+
+  void PredicateSimplifier::Forwards::visitSExtInst(SExtInst &SI) {
+    VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &SI);
+    LLVMContext &Context = SI.getContext();
+    uint32_t SrcBitWidth = cast<IntegerType>(SI.getSrcTy())->getBitWidth();
+    uint32_t DstBitWidth = cast<IntegerType>(SI.getDestTy())->getBitWidth();
+    APInt Min(APInt::getHighBitsSet(DstBitWidth, DstBitWidth-SrcBitWidth+1));
+    APInt Max(APInt::getLowBitsSet(DstBitWidth, SrcBitWidth-1));
+    VRP.add(ConstantInt::get(Context, Min), &SI, ICmpInst::ICMP_SLE);
+    VRP.add(ConstantInt::get(Context, Max), &SI, ICmpInst::ICMP_SGE);
+    VRP.solve();
+  }
+
+  void PredicateSimplifier::Forwards::visitZExtInst(ZExtInst &ZI) {
+    VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &ZI);
+    LLVMContext &Context = ZI.getContext();
+    uint32_t SrcBitWidth = cast<IntegerType>(ZI.getSrcTy())->getBitWidth();
+    uint32_t DstBitWidth = cast<IntegerType>(ZI.getDestTy())->getBitWidth();
+    APInt Max(APInt::getLowBitsSet(DstBitWidth, SrcBitWidth));
+    VRP.add(ConstantInt::get(Context, Max), &ZI, ICmpInst::ICMP_UGE);
     VRP.solve();
   }
 
@@ -1734,26 +2573,132 @@ namespace {
     Instruction::BinaryOps ops = BO.getOpcode();
 
     switch (ops) {
-    case Instruction::URem:
-    case Instruction::SRem:
-    case Instruction::UDiv:
-    case Instruction::SDiv: {
-      Value *Divisor = BO.getOperand(1);
-      VRPSolver VRP(IG, UB, PS->Forest, PS->modified, &BO);
-      VRP.add(Constant::getNullValue(Divisor->getType()), Divisor,
-              ICmpInst::ICMP_NE);
-      VRP.solve();
-      break;
-    }
-    default:
-      break;
+    default: break;
+      case Instruction::URem:
+      case Instruction::SRem:
+      case Instruction::UDiv:
+      case Instruction::SDiv: {
+        Value *Divisor = BO.getOperand(1);
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO);
+        VRP.add(Constant::getNullValue(Divisor->getType()), 
+                Divisor, ICmpInst::ICMP_NE);
+        VRP.solve();
+        break;
+      }
+    }
+
+    switch (ops) {
+      default: break;
+      case Instruction::Shl: {
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO);
+        VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_UGE);
+        VRP.solve();
+      } break;
+      case Instruction::AShr: {
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO);
+        VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_SLE);
+        VRP.solve();
+      } break;
+      case Instruction::LShr:
+      case Instruction::UDiv: {
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO);
+        VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_ULE);
+        VRP.solve();
+      } break;
+      case Instruction::URem: {
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO);
+        VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_ULE);
+        VRP.solve();
+      } break;
+      case Instruction::And: {
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO);
+        VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_ULE);
+        VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_ULE);
+        VRP.solve();
+      } break;
+      case Instruction::Or: {
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO);
+        VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_UGE);
+        VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_UGE);
+        VRP.solve();
+      } break;
     }
   }
 
-  RegisterPass<PredicateSimplifier> X("predsimplify",
-                                      "Predicate Simplifier");
+  void PredicateSimplifier::Forwards::visitICmpInst(ICmpInst &IC) {
+    // If possible, squeeze the ICmp predicate into something simpler.
+    // Eg., if x = [0, 4) and we're being asked icmp uge %x, 3 then change
+    // the predicate to eq.
+
+    // XXX: once we do full PHI handling, modifying the instruction in the
+    // Forwards visitor will cause missed optimizations.
+
+    ICmpInst::Predicate Pred = IC.getPredicate();
+
+    switch (Pred) {
+      default: break;
+      case ICmpInst::ICMP_ULE: Pred = ICmpInst::ICMP_ULT; break;
+      case ICmpInst::ICMP_UGE: Pred = ICmpInst::ICMP_UGT; break;
+      case ICmpInst::ICMP_SLE: Pred = ICmpInst::ICMP_SLT; break;
+      case ICmpInst::ICMP_SGE: Pred = ICmpInst::ICMP_SGT; break;
+    }
+    if (Pred != IC.getPredicate()) {
+      VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &IC);
+      if (VRP.isRelatedBy(IC.getOperand(1), IC.getOperand(0),
+                          ICmpInst::ICMP_NE)) {
+        ++NumSnuggle;
+        PS->modified = true;
+        IC.setPredicate(Pred);
+      }
+    }
+
+    Pred = IC.getPredicate();
+
+    LLVMContext &Context = IC.getContext();
+
+    if (ConstantInt *Op1 = dyn_cast<ConstantInt>(IC.getOperand(1))) {
+      ConstantInt *NextVal = 0;
+      switch (Pred) {
+        default: break;
+        case ICmpInst::ICMP_SLT:
+        case ICmpInst::ICMP_ULT:
+          if (Op1->getValue() != 0)
+            NextVal = ConstantInt::get(Context, Op1->getValue()-1);
+         break;
+        case ICmpInst::ICMP_SGT:
+        case ICmpInst::ICMP_UGT:
+          if (!Op1->getValue().isAllOnesValue())
+            NextVal = ConstantInt::get(Context, Op1->getValue()+1);
+         break;
+      }
+
+      if (NextVal) {
+        VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &IC);
+        if (VRP.isRelatedBy(IC.getOperand(0), NextVal,
+                            ICmpInst::getInversePredicate(Pred))) {
+          ICmpInst *NewIC = new ICmpInst(&IC, ICmpInst::ICMP_EQ, 
+                                         IC.getOperand(0), NextVal, "");
+          NewIC->takeName(&IC);
+          IC.replaceAllUsesWith(NewIC);
+
+          // XXX: prove this isn't necessary
+          if (unsigned n = VN.valueNumber(&IC, PS->DTDFS->getRootNode()))
+            if (VN.value(n) == &IC) IG.remove(n);
+          VN.remove(&IC);
+
+          IC.eraseFromParent();
+          ++NumSnuggle;
+          PS->modified = true;
+        }
+      }
+    }
+  }
 }
 
+char PredicateSimplifier::ID = 0;
+static RegisterPass<PredicateSimplifier>
+X("predsimplify", "Predicate Simplifier");
+
 FunctionPass *llvm::createPredicateSimplifierPass() {
   return new PredicateSimplifier();
 }