1 files changed, 1885 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/GVNPRE.cpp b/lib/Transforms/Scalar/GVNPRE.cpp
new file mode 100644
index 0000000..e3b0937
--- /dev/null
+++ b/lib/Transforms/Scalar/GVNPRE.cpp
@@ -0,0 +1,1885 @@
+//===- GVNPRE.cpp - Eliminate redundant values and expressions ------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass performs a hybrid of global value numbering and partial redundancy
+// elimination, known as GVN-PRE.  It performs partial redundancy elimination on
+// values, rather than lexical expressions, allowing a more comprehensive view 
+// the optimization.  It replaces redundant values with uses of earlier 
+// occurences of the same value.  While this is beneficial in that it eliminates
+// unneeded computation, it also increases register pressure by creating large
+// live ranges, and should be used with caution on platforms that are very 
+// sensitive to register pressure.
+//
+// Note that this pass does the value numbering itself, it does not use the
+// ValueNumbering analysis passes.
+//
+//===----------------------------------------------------------------------===//
+
+#define DEBUG_TYPE "gvnpre"
+#include "llvm/Value.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Instructions.h"
+#include "llvm/Function.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Analysis/Dominators.h"
+#include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/DenseMap.h"
+#include "llvm/ADT/DepthFirstIterator.h"
+#include "llvm/ADT/PostOrderIterator.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/Transforms/Utils/UnifyFunctionExitNodes.h"
+#include "llvm/Support/CFG.h"
+#include "llvm/Support/Compiler.h"
+#include "llvm/Support/Debug.h"
+#include <algorithm>
+#include <deque>
+#include <map>
+using namespace llvm;
+
+//===----------------------------------------------------------------------===//
+//                         ValueTable Class
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+/// This class holds the mapping between values and value numbers.  It is used
+/// as an efficient mechanism to determine the expression-wise equivalence of
+/// two values.
+
+struct Expression {
+  enum ExpressionOpcode { ADD, SUB, MUL, UDIV, SDIV, FDIV, UREM, SREM, 
+                          FREM, SHL, LSHR, ASHR, AND, OR, XOR, ICMPEQ, 
+                          ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE, 
+                          ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ, 
+                          FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE, 
+                          FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE, 
+                          FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
+                          SHUFFLE, SELECT, TRUNC, ZEXT, SEXT, FPTOUI,
+                          FPTOSI, UITOFP, SITOFP, FPTRUNC, FPEXT, 
+                          PTRTOINT, INTTOPTR, BITCAST, GEP, EMPTY,
+                          TOMBSTONE };
+
+  ExpressionOpcode opcode;
+  const Type* type;
+  uint32_t firstVN;
+  uint32_t secondVN;
+  uint32_t thirdVN;
+  SmallVector<uint32_t, 4> varargs;
+  
+  Expression() { }
+  explicit Expression(ExpressionOpcode o) : opcode(o) { }
+  
+  bool operator==(const Expression &other) const {
+    if (opcode != other.opcode)
+      return false;
+    else if (opcode == EMPTY || opcode == TOMBSTONE)
+      return true;
+    else if (type != other.type)
+      return false;
+    else if (firstVN != other.firstVN)
+      return false;
+    else if (secondVN != other.secondVN)
+      return false;
+    else if (thirdVN != other.thirdVN)
+      return false;
+    else {
+      if (varargs.size() != other.varargs.size())
+        return false;
+      
+      for (size_t i = 0; i < varargs.size(); ++i)
+        if (varargs[i] != other.varargs[i])
+          return false;
+    
+      return true;
+    }
+  }
+  
+  bool operator!=(const Expression &other) const {
+    if (opcode != other.opcode)
+      return true;
+    else if (opcode == EMPTY || opcode == TOMBSTONE)
+      return false;
+    else if (type != other.type)
+      return true;
+    else if (firstVN != other.firstVN)
+      return true;
+    else if (secondVN != other.secondVN)
+      return true;
+    else if (thirdVN != other.thirdVN)
+      return true;
+    else {
+      if (varargs.size() != other.varargs.size())
+        return true;
+      
+      for (size_t i = 0; i < varargs.size(); ++i)
+        if (varargs[i] != other.varargs[i])
+          return true;
+    
+      return false;
+    }
+  }
+};
+
+}
+
+namespace {
+  class VISIBILITY_HIDDEN ValueTable {
+    private:
+      DenseMap<Value*, uint32_t> valueNumbering;
+      DenseMap<Expression, uint32_t> expressionNumbering;
+  
+      uint32_t nextValueNumber;
+    
+      Expression::ExpressionOpcode getOpcode(BinaryOperator* BO);
+      Expression::ExpressionOpcode getOpcode(CmpInst* C);
+      Expression::ExpressionOpcode getOpcode(CastInst* C);
+      Expression create_expression(BinaryOperator* BO);
+      Expression create_expression(CmpInst* C);
+      Expression create_expression(ShuffleVectorInst* V);
+      Expression create_expression(ExtractElementInst* C);
+      Expression create_expression(InsertElementInst* V);
+      Expression create_expression(SelectInst* V);
+      Expression create_expression(CastInst* C);
+      Expression create_expression(GetElementPtrInst* G);
+    public:
+      ValueTable() { nextValueNumber = 1; }
+      uint32_t lookup_or_add(Value* V);
+      uint32_t lookup(Value* V) const;
+      void add(Value* V, uint32_t num);
+      void clear();
+      void erase(Value* v);
+      unsigned size();
+  };
+}
+
+namespace llvm {
+template <> struct DenseMapInfo<Expression> {
+  static inline Expression getEmptyKey() {
+    return Expression(Expression::EMPTY);
+  }
+  
+  static inline Expression getTombstoneKey() {
+    return Expression(Expression::TOMBSTONE);
+  }
+  
+  static unsigned getHashValue(const Expression e) {
+    unsigned hash = e.opcode;
+    
+    hash = e.firstVN + hash * 37;
+    hash = e.secondVN + hash * 37;
+    hash = e.thirdVN + hash * 37;
+    
+    hash = ((unsigned)((uintptr_t)e.type >> 4) ^
+            (unsigned)((uintptr_t)e.type >> 9)) +
+           hash * 37;
+    
+    for (SmallVector<uint32_t, 4>::const_iterator I = e.varargs.begin(),
+         E = e.varargs.end(); I != E; ++I)
+      hash = *I + hash * 37;
+    
+    return hash;
+  }
+  static bool isEqual(const Expression &LHS, const Expression &RHS) {
+    return LHS == RHS;
+  }
+  static bool isPod() { return true; }
+};
+}
+
+//===----------------------------------------------------------------------===//
+//                     ValueTable Internal Functions
+//===----------------------------------------------------------------------===//
+Expression::ExpressionOpcode 
+                             ValueTable::getOpcode(BinaryOperator* BO) {
+  switch(BO->getOpcode()) {
+    case Instruction::Add:
+      return Expression::ADD;
+    case Instruction::Sub:
+      return Expression::SUB;
+    case Instruction::Mul:
+      return Expression::MUL;
+    case Instruction::UDiv:
+      return Expression::UDIV;
+    case Instruction::SDiv:
+      return Expression::SDIV;
+    case Instruction::FDiv:
+      return Expression::FDIV;
+    case Instruction::URem:
+      return Expression::UREM;
+    case Instruction::SRem:
+      return Expression::SREM;
+    case Instruction::FRem:
+      return Expression::FREM;
+    case Instruction::Shl:
+      return Expression::SHL;
+    case Instruction::LShr:
+      return Expression::LSHR;
+    case Instruction::AShr:
+      return Expression::ASHR;
+    case Instruction::And:
+      return Expression::AND;
+    case Instruction::Or:
+      return Expression::OR;
+    case Instruction::Xor:
+      return Expression::XOR;
+    
+    // THIS SHOULD NEVER HAPPEN
+    default:
+      assert(0 && "Binary operator with unknown opcode?");
+      return Expression::ADD;
+  }
+}
+
+Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
+  if (C->getOpcode() == Instruction::ICmp) {
+    switch (C->getPredicate()) {
+      case ICmpInst::ICMP_EQ:
+        return Expression::ICMPEQ;
+      case ICmpInst::ICMP_NE:
+        return Expression::ICMPNE;
+      case ICmpInst::ICMP_UGT:
+        return Expression::ICMPUGT;
+      case ICmpInst::ICMP_UGE:
+        return Expression::ICMPUGE;
+      case ICmpInst::ICMP_ULT:
+        return Expression::ICMPULT;
+      case ICmpInst::ICMP_ULE:
+        return Expression::ICMPULE;
+      case ICmpInst::ICMP_SGT:
+        return Expression::ICMPSGT;
+      case ICmpInst::ICMP_SGE:
+        return Expression::ICMPSGE;
+      case ICmpInst::ICMP_SLT:
+        return Expression::ICMPSLT;
+      case ICmpInst::ICMP_SLE:
+        return Expression::ICMPSLE;
+      
+      // THIS SHOULD NEVER HAPPEN
+      default:
+        assert(0 && "Comparison with unknown predicate?");
+        return Expression::ICMPEQ;
+    }
+  } else {
+    switch (C->getPredicate()) {
+      case FCmpInst::FCMP_OEQ:
+        return Expression::FCMPOEQ;
+      case FCmpInst::FCMP_OGT:
+        return Expression::FCMPOGT;
+      case FCmpInst::FCMP_OGE:
+        return Expression::FCMPOGE;
+      case FCmpInst::FCMP_OLT:
+        return Expression::FCMPOLT;
+      case FCmpInst::FCMP_OLE:
+        return Expression::FCMPOLE;
+      case FCmpInst::FCMP_ONE:
+        return Expression::FCMPONE;
+      case FCmpInst::FCMP_ORD:
+        return Expression::FCMPORD;
+      case FCmpInst::FCMP_UNO:
+        return Expression::FCMPUNO;
+      case FCmpInst::FCMP_UEQ:
+        return Expression::FCMPUEQ;
+      case FCmpInst::FCMP_UGT:
+        return Expression::FCMPUGT;
+      case FCmpInst::FCMP_UGE:
+        return Expression::FCMPUGE;
+      case FCmpInst::FCMP_ULT:
+        return Expression::FCMPULT;
+      case FCmpInst::FCMP_ULE:
+        return Expression::FCMPULE;
+      case FCmpInst::FCMP_UNE:
+        return Expression::FCMPUNE;
+      
+      // THIS SHOULD NEVER HAPPEN
+      default:
+        assert(0 && "Comparison with unknown predicate?");
+        return Expression::FCMPOEQ;
+    }
+  }
+}
+
+Expression::ExpressionOpcode 
+                             ValueTable::getOpcode(CastInst* C) {
+  switch(C->getOpcode()) {
+    case Instruction::Trunc:
+      return Expression::TRUNC;
+    case Instruction::ZExt:
+      return Expression::ZEXT;
+    case Instruction::SExt:
+      return Expression::SEXT;
+    case Instruction::FPToUI:
+      return Expression::FPTOUI;
+    case Instruction::FPToSI:
+      return Expression::FPTOSI;
+    case Instruction::UIToFP:
+      return Expression::UITOFP;
+    case Instruction::SIToFP:
+      return Expression::SITOFP;
+    case Instruction::FPTrunc:
+      return Expression::FPTRUNC;
+    case Instruction::FPExt:
+      return Expression::FPEXT;
+    case Instruction::PtrToInt:
+      return Expression::PTRTOINT;
+    case Instruction::IntToPtr:
+      return Expression::INTTOPTR;
+    case Instruction::BitCast:
+      return Expression::BITCAST;
+    
+    // THIS SHOULD NEVER HAPPEN
+    default:
+      assert(0 && "Cast operator with unknown opcode?");
+      return Expression::BITCAST;
+  }
+}
+
+Expression ValueTable::create_expression(BinaryOperator* BO) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(BO->getOperand(0));
+  e.secondVN = lookup_or_add(BO->getOperand(1));
+  e.thirdVN = 0;
+  e.type = BO->getType();
+  e.opcode = getOpcode(BO);
+  
+  return e;
+}
+
+Expression ValueTable::create_expression(CmpInst* C) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(C->getOperand(0));
+  e.secondVN = lookup_or_add(C->getOperand(1));
+  e.thirdVN = 0;
+  e.type = C->getType();
+  e.opcode = getOpcode(C);
+  
+  return e;
+}
+
+Expression ValueTable::create_expression(CastInst* C) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(C->getOperand(0));
+  e.secondVN = 0;
+  e.thirdVN = 0;
+  e.type = C->getType();
+  e.opcode = getOpcode(C);
+  
+  return e;
+}
+
+Expression ValueTable::create_expression(ShuffleVectorInst* S) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(S->getOperand(0));
+  e.secondVN = lookup_or_add(S->getOperand(1));
+  e.thirdVN = lookup_or_add(S->getOperand(2));
+  e.type = S->getType();
+  e.opcode = Expression::SHUFFLE;
+  
+  return e;
+}
+
+Expression ValueTable::create_expression(ExtractElementInst* E) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(E->getOperand(0));
+  e.secondVN = lookup_or_add(E->getOperand(1));
+  e.thirdVN = 0;
+  e.type = E->getType();
+  e.opcode = Expression::EXTRACT;
+  
+  return e;
+}
+
+Expression ValueTable::create_expression(InsertElementInst* I) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(I->getOperand(0));
+  e.secondVN = lookup_or_add(I->getOperand(1));
+  e.thirdVN = lookup_or_add(I->getOperand(2));
+  e.type = I->getType();
+  e.opcode = Expression::INSERT;
+  
+  return e;
+}
+
+Expression ValueTable::create_expression(SelectInst* I) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(I->getCondition());
+  e.secondVN = lookup_or_add(I->getTrueValue());
+  e.thirdVN = lookup_or_add(I->getFalseValue());
+  e.type = I->getType();
+  e.opcode = Expression::SELECT;
+  
+  return e;
+}
+
+Expression ValueTable::create_expression(GetElementPtrInst* G) {
+  Expression e;
+    
+  e.firstVN = lookup_or_add(G->getPointerOperand());
+  e.secondVN = 0;
+  e.thirdVN = 0;
+  e.type = G->getType();
+  e.opcode = Expression::GEP;
+  
+  for (GetElementPtrInst::op_iterator I = G->idx_begin(), E = G->idx_end();
+       I != E; ++I)
+    e.varargs.push_back(lookup_or_add(*I));
+  
+  return e;
+}
+
+//===----------------------------------------------------------------------===//
+//                     ValueTable External Functions
+//===----------------------------------------------------------------------===//
+
+/// lookup_or_add - Returns the value number for the specified value, assigning
+/// it a new number if it did not have one before.
+uint32_t ValueTable::lookup_or_add(Value* V) {
+  DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+  if (VI != valueNumbering.end())
+    return VI->second;
+  
+  
+  if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
+    Expression e = create_expression(BO);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else if (CmpInst* C = dyn_cast<CmpInst>(V)) {
+    Expression e = create_expression(C);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else if (ShuffleVectorInst* U = dyn_cast<ShuffleVectorInst>(V)) {
+    Expression e = create_expression(U);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else if (ExtractElementInst* U = dyn_cast<ExtractElementInst>(V)) {
+    Expression e = create_expression(U);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else if (InsertElementInst* U = dyn_cast<InsertElementInst>(V)) {
+    Expression e = create_expression(U);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else if (SelectInst* U = dyn_cast<SelectInst>(V)) {
+    Expression e = create_expression(U);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else if (CastInst* U = dyn_cast<CastInst>(V)) {
+    Expression e = create_expression(U);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else if (GetElementPtrInst* U = dyn_cast<GetElementPtrInst>(V)) {
+    Expression e = create_expression(U);
+    
+    DenseMap<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
+    if (EI != expressionNumbering.end()) {
+      valueNumbering.insert(std::make_pair(V, EI->second));
+      return EI->second;
+    } else {
+      expressionNumbering.insert(std::make_pair(e, nextValueNumber));
+      valueNumbering.insert(std::make_pair(V, nextValueNumber));
+      
+      return nextValueNumber++;
+    }
+  } else {
+    valueNumbering.insert(std::make_pair(V, nextValueNumber));
+    return nextValueNumber++;
+  }
+}
+
+/// lookup - Returns the value number of the specified value. Fails if
+/// the value has not yet been numbered.
+uint32_t ValueTable::lookup(Value* V) const {
+  DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+  if (VI != valueNumbering.end())
+    return VI->second;
+  else
+    assert(0 && "Value not numbered?");
+  
+  return 0;
+}
+
+/// add - Add the specified value with the given value number, removing
+/// its old number, if any
+void ValueTable::add(Value* V, uint32_t num) {
+  DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
+  if (VI != valueNumbering.end())
+    valueNumbering.erase(VI);
+  valueNumbering.insert(std::make_pair(V, num));
+}
+
+/// clear - Remove all entries from the ValueTable
+void ValueTable::clear() {
+  valueNumbering.clear();
+  expressionNumbering.clear();
+  nextValueNumber = 1;
+}
+
+/// erase - Remove a value from the value numbering
+void ValueTable::erase(Value* V) {
+  valueNumbering.erase(V);
+}
+
+/// size - Return the number of assigned value numbers
+unsigned ValueTable::size() {
+  // NOTE: zero is never assigned
+  return nextValueNumber;
+}
+
+namespace {
+
+//===----------------------------------------------------------------------===//
+//                       ValueNumberedSet Class
+//===----------------------------------------------------------------------===//
+
+class ValueNumberedSet {
+  private:
+    SmallPtrSet<Value*, 8> contents;
+    BitVector numbers;
+  public:
+    ValueNumberedSet() { numbers.resize(1); }
+    ValueNumberedSet(const ValueNumberedSet& other) {
+      numbers = other.numbers;
+      contents = other.contents;
+    }
+    
+    typedef SmallPtrSet<Value*, 8>::iterator iterator;
+    
+    iterator begin() { return contents.begin(); }
+    iterator end() { return contents.end(); }
+    
+    bool insert(Value* v) { return contents.insert(v); }
+    void insert(iterator I, iterator E) { contents.insert(I, E); }
+    void erase(Value* v) { contents.erase(v); }
+    unsigned count(Value* v) { return contents.count(v); }
+    size_t size() { return contents.size(); }
+    
+    void set(unsigned i)  {
+      if (i >= numbers.size())
+        numbers.resize(i+1);
+      
+      numbers.set(i);
+    }
+    
+    void operator=(const ValueNumberedSet& other) {
+      contents = other.contents;
+      numbers = other.numbers;
+    }
+    
+    void reset(unsigned i)  {
+      if (i < numbers.size())
+        numbers.reset(i);
+    }
+    
+    bool test(unsigned i)  {
+      if (i >= numbers.size())
+        return false;
+      
+      return numbers.test(i);
+    }
+    
+    void clear() {
+      contents.clear();
+      numbers.clear();
+    }
+};
+
+}
+
+//===----------------------------------------------------------------------===//
+//                         GVNPRE Pass
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+  class VISIBILITY_HIDDEN GVNPRE : public FunctionPass {
+    bool runOnFunction(Function &F);
+  public:
+    static char ID; // Pass identification, replacement for typeid
+    GVNPRE() : FunctionPass(&ID) {}
+
+  private:
+    ValueTable VN;
+    SmallVector<Instruction*, 8> createdExpressions;
+    
+    DenseMap<BasicBlock*, ValueNumberedSet> availableOut;
+    DenseMap<BasicBlock*, ValueNumberedSet> anticipatedIn;
+    DenseMap<BasicBlock*, ValueNumberedSet> generatedPhis;
+    
+    // This transformation requires dominator postdominator info
+    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
+      AU.setPreservesCFG();
+      AU.addRequiredID(BreakCriticalEdgesID);
+      AU.addRequired<UnifyFunctionExitNodes>();
+      AU.addRequired<DominatorTree>();
+    }
+  
+    // Helper fuctions
+    // FIXME: eliminate or document these better
+    void dump(ValueNumberedSet& s) const ;
+    void clean(ValueNumberedSet& set) ;
+    Value* find_leader(ValueNumberedSet& vals, uint32_t v) ;
+    Value* phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ) ;
+    void phi_translate_set(ValueNumberedSet& anticIn, BasicBlock* pred,
+                           BasicBlock* succ, ValueNumberedSet& out) ;
+    
+    void topo_sort(ValueNumberedSet& set,
+                   SmallVector<Value*, 8>& vec) ;
+    
+    void cleanup() ;
+    bool elimination() ;
+    
+    void val_insert(ValueNumberedSet& s, Value* v) ;
+    void val_replace(ValueNumberedSet& s, Value* v) ;
+    bool dependsOnInvoke(Value* V) ;
+    void buildsets_availout(BasicBlock::iterator I,
+                            ValueNumberedSet& currAvail,
+                            ValueNumberedSet& currPhis,
+                            ValueNumberedSet& currExps,
+                            SmallPtrSet<Value*, 16>& currTemps);
+    bool buildsets_anticout(BasicBlock* BB,
+                            ValueNumberedSet& anticOut,
+                            SmallPtrSet<BasicBlock*, 8>& visited);
+    unsigned buildsets_anticin(BasicBlock* BB,
+                           ValueNumberedSet& anticOut,
+                           ValueNumberedSet& currExps,
+                           SmallPtrSet<Value*, 16>& currTemps,
+                           SmallPtrSet<BasicBlock*, 8>& visited);
+    void buildsets(Function& F) ;
+    
+    void insertion_pre(Value* e, BasicBlock* BB,
+                       DenseMap<BasicBlock*, Value*>& avail,
+                       std::map<BasicBlock*,ValueNumberedSet>& new_set);
+    unsigned insertion_mergepoint(SmallVector<Value*, 8>& workList,
+                                  df_iterator<DomTreeNode*>& D,
+                      std::map<BasicBlock*, ValueNumberedSet>& new_set);
+    bool insertion(Function& F) ;
+  
+  };
+  
+  char GVNPRE::ID = 0;
+  
+}
+
+// createGVNPREPass - The public interface to this file...
+FunctionPass *llvm::createGVNPREPass() { return new GVNPRE(); }
+
+static RegisterPass<GVNPRE> X("gvnpre",
+                      "Global Value Numbering/Partial Redundancy Elimination");
+
+
+STATISTIC(NumInsertedVals, "Number of values inserted");
+STATISTIC(NumInsertedPhis, "Number of PHI nodes inserted");
+STATISTIC(NumEliminated, "Number of redundant instructions eliminated");
+
+/// find_leader - Given a set and a value number, return the first
+/// element of the set with that value number, or 0 if no such element
+/// is present
+Value* GVNPRE::find_leader(ValueNumberedSet& vals, uint32_t v) {
+  if (!vals.test(v))
+    return 0;
+  
+  for (ValueNumberedSet::iterator I = vals.begin(), E = vals.end();
+       I != E; ++I)
+    if (v == VN.lookup(*I))
+      return *I;
+  
+  assert(0 && "No leader found, but present bit is set?");
+  return 0;
+}
+
+/// val_insert - Insert a value into a set only if there is not a value
+/// with the same value number already in the set
+void GVNPRE::val_insert(ValueNumberedSet& s, Value* v) {
+  uint32_t num = VN.lookup(v);
+  if (!s.test(num))
+    s.insert(v);
+}
+
+/// val_replace - Insert a value into a set, replacing any values already in
+/// the set that have the same value number
+void GVNPRE::val_replace(ValueNumberedSet& s, Value* v) {
+  if (s.count(v)) return;
+  
+  uint32_t num = VN.lookup(v);
+  Value* leader = find_leader(s, num);
+  if (leader != 0)
+    s.erase(leader);
+  s.insert(v);
+  s.set(num);
+}
+
+/// phi_translate - Given a value, its parent block, and a predecessor of its
+/// parent, translate the value into legal for the predecessor block.  This 
+/// means translating its operands (and recursively, their operands) through
+/// any phi nodes in the parent into values available in the predecessor
+Value* GVNPRE::phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ) {
+  if (V == 0)
+    return 0;
+  
+  // Unary Operations
+  if (CastInst* U = dyn_cast<CastInst>(V)) {
+    Value* newOp1 = 0;
+    if (isa<Instruction>(U->getOperand(0)))
+      newOp1 = phi_translate(U->getOperand(0), pred, succ);
+    else
+      newOp1 = U->getOperand(0);
+    
+    if (newOp1 == 0)
+      return 0;
+    
+    if (newOp1 != U->getOperand(0)) {
+      Instruction* newVal = 0;
+      if (CastInst* C = dyn_cast<CastInst>(U))
+        newVal = CastInst::Create(C->getOpcode(),
+                                  newOp1, C->getType(),
+                                  C->getName()+".expr");
+      
+      uint32_t v = VN.lookup_or_add(newVal);
+      
+      Value* leader = find_leader(availableOut[pred], v);
+      if (leader == 0) {
+        createdExpressions.push_back(newVal);
+        return newVal;
+      } else {
+        VN.erase(newVal);
+        delete newVal;
+        return leader;
+      }
+    }
+  
+  // Binary Operations
+  } if (isa<BinaryOperator>(V) || isa<CmpInst>(V) || 
+      isa<ExtractElementInst>(V)) {
+    User* U = cast<User>(V);
+    
+    Value* newOp1 = 0;
+    if (isa<Instruction>(U->getOperand(0)))
+      newOp1 = phi_translate(U->getOperand(0), pred, succ);
+    else
+      newOp1 = U->getOperand(0);
+    
+    if (newOp1 == 0)
+      return 0;
+    
+    Value* newOp2 = 0;
+    if (isa<Instruction>(U->getOperand(1)))
+      newOp2 = phi_translate(U->getOperand(1), pred, succ);
+    else
+      newOp2 = U->getOperand(1);
+    
+    if (newOp2 == 0)
+      return 0;
+    
+    if (newOp1 != U->getOperand(0) || newOp2 != U->getOperand(1)) {
+      Instruction* newVal = 0;
+      if (BinaryOperator* BO = dyn_cast<BinaryOperator>(U))
+        newVal = BinaryOperator::Create(BO->getOpcode(),
+                                        newOp1, newOp2,
+                                        BO->getName()+".expr");
+      else if (CmpInst* C = dyn_cast<CmpInst>(U))
+        newVal = CmpInst::Create(C->getOpcode(),
+                                 C->getPredicate(),
+                                 newOp1, newOp2,
+                                 C->getName()+".expr");
+      else if (ExtractElementInst* E = dyn_cast<ExtractElementInst>(U))
+        newVal = new ExtractElementInst(newOp1, newOp2, E->getName()+".expr");
+      
+      uint32_t v = VN.lookup_or_add(newVal);
+      
+      Value* leader = find_leader(availableOut[pred], v);
+      if (leader == 0) {
+        createdExpressions.push_back(newVal);
+        return newVal;
+      } else {
+        VN.erase(newVal);
+        delete newVal;
+        return leader;
+      }
+    }
+  
+  // Ternary Operations
+  } else if (isa<ShuffleVectorInst>(V) || isa<InsertElementInst>(V) ||
+             isa<SelectInst>(V)) {
+    User* U = cast<User>(V);
+    
+    Value* newOp1 = 0;
+    if (isa<Instruction>(U->getOperand(0)))
+      newOp1 = phi_translate(U->getOperand(0), pred, succ);
+    else
+      newOp1 = U->getOperand(0);
+    
+    if (newOp1 == 0)
+      return 0;
+    
+    Value* newOp2 = 0;
+    if (isa<Instruction>(U->getOperand(1)))
+      newOp2 = phi_translate(U->getOperand(1), pred, succ);
+    else
+      newOp2 = U->getOperand(1);
+    
+    if (newOp2 == 0)
+      return 0;
+    
+    Value* newOp3 = 0;
+    if (isa<Instruction>(U->getOperand(2)))
+      newOp3 = phi_translate(U->getOperand(2), pred, succ);
+    else
+      newOp3 = U->getOperand(2);
+    
+    if (newOp3 == 0)
+      return 0;
+    
+    if (newOp1 != U->getOperand(0) ||
+        newOp2 != U->getOperand(1) ||
+        newOp3 != U->getOperand(2)) {
+      Instruction* newVal = 0;
+      if (ShuffleVectorInst* S = dyn_cast<ShuffleVectorInst>(U))
+        newVal = new ShuffleVectorInst(newOp1, newOp2, newOp3,
+                                       S->getName() + ".expr");
+      else if (InsertElementInst* I = dyn_cast<InsertElementInst>(U))
+        newVal = InsertElementInst::Create(newOp1, newOp2, newOp3,
+                                           I->getName() + ".expr");
+      else if (SelectInst* I = dyn_cast<SelectInst>(U))
+        newVal = SelectInst::Create(newOp1, newOp2, newOp3,
+                                    I->getName() + ".expr");
+      
+      uint32_t v = VN.lookup_or_add(newVal);
+      
+      Value* leader = find_leader(availableOut[pred], v);
+      if (leader == 0) {
+        createdExpressions.push_back(newVal);
+        return newVal;
+      } else {
+        VN.erase(newVal);
+        delete newVal;
+        return leader;
+      }
+    }
+  
+  // Varargs operators
+  } else if (GetElementPtrInst* U = dyn_cast<GetElementPtrInst>(V)) {
+    Value* newOp1 = 0;
+    if (isa<Instruction>(U->getPointerOperand()))
+      newOp1 = phi_translate(U->getPointerOperand(), pred, succ);
+    else
+      newOp1 = U->getPointerOperand();
+    
+    if (newOp1 == 0)
+      return 0;
+    
+    bool changed_idx = false;
+    SmallVector<Value*, 4> newIdx;
+    for (GetElementPtrInst::op_iterator I = U->idx_begin(), E = U->idx_end();
+         I != E; ++I)
+      if (isa<Instruction>(*I)) {
+        Value* newVal = phi_translate(*I, pred, succ);
+        newIdx.push_back(newVal);
+        if (newVal != *I)
+          changed_idx = true;
+      } else {
+        newIdx.push_back(*I);
+      }
+    
+    if (newOp1 != U->getPointerOperand() || changed_idx) {
+      Instruction* newVal =
+          GetElementPtrInst::Create(newOp1,
+                                    newIdx.begin(), newIdx.end(),
+                                    U->getName()+".expr");
+      
+      uint32_t v = VN.lookup_or_add(newVal);
+      
+      Value* leader = find_leader(availableOut[pred], v);
+      if (leader == 0) {
+        createdExpressions.push_back(newVal);
+        return newVal;
+      } else {
+        VN.erase(newVal);
+        delete newVal;
+        return leader;
+      }
+    }
+  
+  // PHI Nodes
+  } else if (PHINode* P = dyn_cast<PHINode>(V)) {
+    if (P->getParent() == succ)
+      return P->getIncomingValueForBlock(pred);
+  }
+  
+  return V;
+}
+
+/// phi_translate_set - Perform phi translation on every element of a set
+void GVNPRE::phi_translate_set(ValueNumberedSet& anticIn,
+                              BasicBlock* pred, BasicBlock* succ,
+                              ValueNumberedSet& out) {
+  for (ValueNumberedSet::iterator I = anticIn.begin(),
+       E = anticIn.end(); I != E; ++I) {
+    Value* V = phi_translate(*I, pred, succ);
+    if (V != 0 && !out.test(VN.lookup_or_add(V))) {
+      out.insert(V);
+      out.set(VN.lookup(V));
+    }
+  }
+}
+
+/// dependsOnInvoke - Test if a value has an phi node as an operand, any of 
+/// whose inputs is an invoke instruction.  If this is true, we cannot safely
+/// PRE the instruction or anything that depends on it.
+bool GVNPRE::dependsOnInvoke(Value* V) {
+  if (PHINode* p = dyn_cast<PHINode>(V)) {
+    for (PHINode::op_iterator I = p->op_begin(), E = p->op_end(); I != E; ++I)
+      if (isa<InvokeInst>(*I))
+        return true;
+    return false;
+  } else {
+    return false;
+  }
+}
+
+/// clean - Remove all non-opaque values from the set whose operands are not
+/// themselves in the set, as well as all values that depend on invokes (see 
+/// above)
+void GVNPRE::clean(ValueNumberedSet& set) {
+  SmallVector<Value*, 8> worklist;
+  worklist.reserve(set.size());
+  topo_sort(set, worklist);
+  
+  for (unsigned i = 0; i < worklist.size(); ++i) {
+    Value* v = worklist[i];
+    
+    // Handle unary ops
+    if (CastInst* U = dyn_cast<CastInst>(v)) {
+      bool lhsValid = !isa<Instruction>(U->getOperand(0));
+      lhsValid |= set.test(VN.lookup(U->getOperand(0)));
+      if (lhsValid)
+        lhsValid = !dependsOnInvoke(U->getOperand(0));
+      
+      if (!lhsValid) {
+        set.erase(U);
+        set.reset(VN.lookup(U));
+      }
+    
+    // Handle binary ops
+    } else if (isa<BinaryOperator>(v) || isa<CmpInst>(v) ||
+        isa<ExtractElementInst>(v)) {
+      User* U = cast<User>(v);
+      
+      bool lhsValid = !isa<Instruction>(U->getOperand(0));
+      lhsValid |= set.test(VN.lookup(U->getOperand(0)));
+      if (lhsValid)
+        lhsValid = !dependsOnInvoke(U->getOperand(0));
+    
+      bool rhsValid = !isa<Instruction>(U->getOperand(1));
+      rhsValid |= set.test(VN.lookup(U->getOperand(1)));
+      if (rhsValid)
+        rhsValid = !dependsOnInvoke(U->getOperand(1));
+      
+      if (!lhsValid || !rhsValid) {
+        set.erase(U);
+        set.reset(VN.lookup(U));
+      }
+    
+    // Handle ternary ops
+    } else if (isa<ShuffleVectorInst>(v) || isa<InsertElementInst>(v) ||
+               isa<SelectInst>(v)) {
+      User* U = cast<User>(v);
+    
+      bool lhsValid = !isa<Instruction>(U->getOperand(0));
+      lhsValid |= set.test(VN.lookup(U->getOperand(0)));
+      if (lhsValid)
+        lhsValid = !dependsOnInvoke(U->getOperand(0));
+      
+      bool rhsValid = !isa<Instruction>(U->getOperand(1));
+      rhsValid |= set.test(VN.lookup(U->getOperand(1)));
+      if (rhsValid)
+        rhsValid = !dependsOnInvoke(U->getOperand(1));
+      
+      bool thirdValid = !isa<Instruction>(U->getOperand(2));
+      thirdValid |= set.test(VN.lookup(U->getOperand(2)));
+      if (thirdValid)
+        thirdValid = !dependsOnInvoke(U->getOperand(2));
+    
+      if (!lhsValid || !rhsValid || !thirdValid) {
+        set.erase(U);
+        set.reset(VN.lookup(U));
+      }
+    
+    // Handle varargs ops
+    } else if (GetElementPtrInst* U = dyn_cast<GetElementPtrInst>(v)) {
+      bool ptrValid = !isa<Instruction>(U->getPointerOperand());
+      ptrValid |= set.test(VN.lookup(U->getPointerOperand()));
+      if (ptrValid)
+        ptrValid = !dependsOnInvoke(U->getPointerOperand());
+      
+      bool varValid = true;
+      for (GetElementPtrInst::op_iterator I = U->idx_begin(), E = U->idx_end();
+           I != E; ++I)
+        if (varValid) {
+          varValid &= !isa<Instruction>(*I) || set.test(VN.lookup(*I));
+          varValid &= !dependsOnInvoke(*I);
+        }
+    
+      if (!ptrValid || !varValid) {
+        set.erase(U);
+        set.reset(VN.lookup(U));
+      }
+    }
+  }
+}
+
+/// topo_sort - Given a set of values, sort them by topological
+/// order into the provided vector.
+void GVNPRE::topo_sort(ValueNumberedSet& set, SmallVector<Value*, 8>& vec) {
+  SmallPtrSet<Value*, 16> visited;
+  SmallVector<Value*, 8> stack;
+  for (ValueNumberedSet::iterator I = set.begin(), E = set.end();
+       I != E; ++I) {
+    if (visited.count(*I) == 0)
+      stack.push_back(*I);
+    
+    while (!stack.empty()) {
+      Value* e = stack.back();
+      
+      // Handle unary ops
+      if (CastInst* U = dyn_cast<CastInst>(e)) {
+        Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
+    
+        if (l != 0 && isa<Instruction>(l) &&
+            visited.count(l) == 0)
+          stack.push_back(l);
+        else {
+          vec.push_back(e);
+          visited.insert(e);
+          stack.pop_back();
+        }
+      
+      // Handle binary ops
+      } else if (isa<BinaryOperator>(e) || isa<CmpInst>(e) ||
+          isa<ExtractElementInst>(e)) {
+        User* U = cast<User>(e);
+        Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
+        Value* r = find_leader(set, VN.lookup(U->getOperand(1)));
+    
+        if (l != 0 && isa<Instruction>(l) &&
+            visited.count(l) == 0)
+          stack.push_back(l);
+        else if (r != 0 && isa<Instruction>(r) &&
+                 visited.count(r) == 0)
+          stack.push_back(r);
+        else {
+          vec.push_back(e);
+          visited.insert(e);
+          stack.pop_back();
+        }
+      
+      // Handle ternary ops
+      } else if (isa<InsertElementInst>(e) || isa<ShuffleVectorInst>(e) ||
+                 isa<SelectInst>(e)) {
+        User* U = cast<User>(e);
+        Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
+        Value* r = find_leader(set, VN.lookup(U->getOperand(1)));
+        Value* m = find_leader(set, VN.lookup(U->getOperand(2)));
+      
+        if (l != 0 && isa<Instruction>(l) &&
+            visited.count(l) == 0)
+          stack.push_back(l);
+        else if (r != 0 && isa<Instruction>(r) &&
+                 visited.count(r) == 0)
+          stack.push_back(r);
+        else if (m != 0 && isa<Instruction>(m) &&
+                 visited.count(m) == 0)
+          stack.push_back(m);
+        else {
+          vec.push_back(e);
+          visited.insert(e);
+          stack.pop_back();
+        }
+      
+      // Handle vararg ops
+      } else if (GetElementPtrInst* U = dyn_cast<GetElementPtrInst>(e)) {
+        Value* p = find_leader(set, VN.lookup(U->getPointerOperand()));
+        
+        if (p != 0 && isa<Instruction>(p) &&
+            visited.count(p) == 0)
+          stack.push_back(p);
+        else {
+          bool push_va = false;
+          for (GetElementPtrInst::op_iterator I = U->idx_begin(),
+               E = U->idx_end(); I != E; ++I) {
+            Value * v = find_leader(set, VN.lookup(*I));
+            if (v != 0 && isa<Instruction>(v) && visited.count(v) == 0) {
+              stack.push_back(v);
+              push_va = true;
+            }
+          }
+          
+          if (!push_va) {
+            vec.push_back(e);
+            visited.insert(e);
+            stack.pop_back();
+          }
+        }
+      
+      // Handle opaque ops
+      } else {
+        visited.insert(e);
+        vec.push_back(e);
+        stack.pop_back();
+      }
+    }
+    
+    stack.clear();
+  }
+}
+
+/// dump - Dump a set of values to standard error
+void GVNPRE::dump(ValueNumberedSet& s) const {
+  DOUT << "{ ";
+  for (ValueNumberedSet::iterator I = s.begin(), E = s.end();
+       I != E; ++I) {
+    DOUT << "" << VN.lookup(*I) << ": ";
+    DEBUG((*I)->dump());
+  }
+  DOUT << "}\n\n";
+}
+
+/// elimination - Phase 3 of the main algorithm.  Perform full redundancy 
+/// elimination by walking the dominator tree and removing any instruction that 
+/// is dominated by another instruction with the same value number.
+bool GVNPRE::elimination() {
+  bool changed_function = false;
+  
+  SmallVector<std::pair<Instruction*, Value*>, 8> replace;
+  SmallVector<Instruction*, 8> erase;
+  
+  DominatorTree& DT = getAnalysis<DominatorTree>();
+  
+  for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
+         E = df_end(DT.getRootNode()); DI != E; ++DI) {
+    BasicBlock* BB = DI->getBlock();
+    
+    for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+         BI != BE; ++BI) {
+
+      if (isa<BinaryOperator>(BI) || isa<CmpInst>(BI) ||
+          isa<ShuffleVectorInst>(BI) || isa<InsertElementInst>(BI) ||
+          isa<ExtractElementInst>(BI) || isa<SelectInst>(BI) ||
+          isa<CastInst>(BI) || isa<GetElementPtrInst>(BI)) {
+        
+        if (availableOut[BB].test(VN.lookup(BI)) &&
+            !availableOut[BB].count(BI)) {
+          Value *leader = find_leader(availableOut[BB], VN.lookup(BI));
+          if (Instruction* Instr = dyn_cast<Instruction>(leader))
+            if (Instr->getParent() != 0 && Instr != BI) {
+              replace.push_back(std::make_pair(BI, leader));
+              erase.push_back(BI);
+              ++NumEliminated;
+            }
+        }
+      }
+    }
+  }
+  
+  while (!replace.empty()) {
+    std::pair<Instruction*, Value*> rep = replace.back();
+    replace.pop_back();
+    rep.first->replaceAllUsesWith(rep.second);
+    changed_function = true;
+  }
+    
+  for (SmallVector<Instruction*, 8>::iterator I = erase.begin(),
+       E = erase.end(); I != E; ++I)
+     (*I)->eraseFromParent();
+  
+  return changed_function;
+}
+
+/// cleanup - Delete any extraneous values that were created to represent
+/// expressions without leaders.
+void GVNPRE::cleanup() {
+  while (!createdExpressions.empty()) {
+    Instruction* I = createdExpressions.back();
+    createdExpressions.pop_back();
+    
+    delete I;
+  }
+}
+
+/// buildsets_availout - When calculating availability, handle an instruction
+/// by inserting it into the appropriate sets
+void GVNPRE::buildsets_availout(BasicBlock::iterator I,
+                                ValueNumberedSet& currAvail,
+                                ValueNumberedSet& currPhis,
+                                ValueNumberedSet& currExps,
+                                SmallPtrSet<Value*, 16>& currTemps) {
+  // Handle PHI nodes
+  if (PHINode* p = dyn_cast<PHINode>(I)) {
+    unsigned num = VN.lookup_or_add(p);
+    
+    currPhis.insert(p);
+    currPhis.set(num);
+  
+  // Handle unary ops
+  } else if (CastInst* U = dyn_cast<CastInst>(I)) {
+    Value* leftValue = U->getOperand(0);
+    
+    unsigned num = VN.lookup_or_add(U);
+      
+    if (isa<Instruction>(leftValue))
+      if (!currExps.test(VN.lookup(leftValue))) {
+        currExps.insert(leftValue);
+        currExps.set(VN.lookup(leftValue));
+      }
+    
+    if (!currExps.test(num)) {
+      currExps.insert(U);
+      currExps.set(num);
+    }
+  
+  // Handle binary ops
+  } else if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
+             isa<ExtractElementInst>(I)) {
+    User* U = cast<User>(I);
+    Value* leftValue = U->getOperand(0);
+    Value* rightValue = U->getOperand(1);
+    
+    unsigned num = VN.lookup_or_add(U);
+      
+    if (isa<Instruction>(leftValue))
+      if (!currExps.test(VN.lookup(leftValue))) {
+        currExps.insert(leftValue);
+        currExps.set(VN.lookup(leftValue));
+      }
+    
+    if (isa<Instruction>(rightValue))
+      if (!currExps.test(VN.lookup(rightValue))) {
+        currExps.insert(rightValue);
+        currExps.set(VN.lookup(rightValue));
+      }
+    
+    if (!currExps.test(num)) {
+      currExps.insert(U);
+      currExps.set(num);
+    }
+    
+  // Handle ternary ops
+  } else if (isa<InsertElementInst>(I) || isa<ShuffleVectorInst>(I) ||
+             isa<SelectInst>(I)) {
+    User* U = cast<User>(I);
+    Value* leftValue = U->getOperand(0);
+    Value* rightValue = U->getOperand(1);
+    Value* thirdValue = U->getOperand(2);
+      
+    VN.lookup_or_add(U);
+    
+    unsigned num = VN.lookup_or_add(U);
+    
+    if (isa<Instruction>(leftValue))
+      if (!currExps.test(VN.lookup(leftValue))) {
+        currExps.insert(leftValue);
+        currExps.set(VN.lookup(leftValue));
+      }
+    if (isa<Instruction>(rightValue))
+      if (!currExps.test(VN.lookup(rightValue))) {
+        currExps.insert(rightValue);
+        currExps.set(VN.lookup(rightValue));
+      }
+    if (isa<Instruction>(thirdValue))
+      if (!currExps.test(VN.lookup(thirdValue))) {
+        currExps.insert(thirdValue);
+        currExps.set(VN.lookup(thirdValue));
+      }
+    
+    if (!currExps.test(num)) {
+      currExps.insert(U);
+      currExps.set(num);
+    }
+    
+  // Handle vararg ops
+  } else if (GetElementPtrInst* U = dyn_cast<GetElementPtrInst>(I)) {
+    Value* ptrValue = U->getPointerOperand();
+      
+    VN.lookup_or_add(U);
+    
+    unsigned num = VN.lookup_or_add(U);
+    
+    if (isa<Instruction>(ptrValue))
+      if (!currExps.test(VN.lookup(ptrValue))) {
+        currExps.insert(ptrValue);
+        currExps.set(VN.lookup(ptrValue));
+      }
+    
+    for (GetElementPtrInst::op_iterator OI = U->idx_begin(), OE = U->idx_end();
+         OI != OE; ++OI)
+      if (isa<Instruction>(*OI) && !currExps.test(VN.lookup(*OI))) {
+        currExps.insert(*OI);
+        currExps.set(VN.lookup(*OI));
+      }
+    
+    if (!currExps.test(VN.lookup(U))) {
+      currExps.insert(U);
+      currExps.set(num);
+    }
+    
+  // Handle opaque ops
+  } else if (!I->isTerminator()){
+    VN.lookup_or_add(I);
+    
+    currTemps.insert(I);
+  }
+    
+  if (!I->isTerminator())
+    if (!currAvail.test(VN.lookup(I))) {
+      currAvail.insert(I);
+      currAvail.set(VN.lookup(I));
+    }
+}
+
+/// buildsets_anticout - When walking the postdom tree, calculate the ANTIC_OUT
+/// set as a function of the ANTIC_IN set of the block's predecessors
+bool GVNPRE::buildsets_anticout(BasicBlock* BB,
+                                ValueNumberedSet& anticOut,
+                                SmallPtrSet<BasicBlock*, 8>& visited) {
+  if (BB->getTerminator()->getNumSuccessors() == 1) {
+    if (BB->getTerminator()->getSuccessor(0) != BB &&
+        visited.count(BB->getTerminator()->getSuccessor(0)) == 0) {
+      return true;
+    }
+    else {
+      phi_translate_set(anticipatedIn[BB->getTerminator()->getSuccessor(0)],
+                        BB,  BB->getTerminator()->getSuccessor(0), anticOut);
+    }
+  } else if (BB->getTerminator()->getNumSuccessors() > 1) {
+    BasicBlock* first = BB->getTerminator()->getSuccessor(0);
+    for (ValueNumberedSet::iterator I = anticipatedIn[first].begin(),
+         E = anticipatedIn[first].end(); I != E; ++I) {
+      anticOut.insert(*I);
+      anticOut.set(VN.lookup(*I));
+    }
+    
+    for (unsigned i = 1; i < BB->getTerminator()->getNumSuccessors(); ++i) {
+      BasicBlock* currSucc = BB->getTerminator()->getSuccessor(i);
+      ValueNumberedSet& succAnticIn = anticipatedIn[currSucc];
+      
+      SmallVector<Value*, 16> temp;
+      
+      for (ValueNumberedSet::iterator I = anticOut.begin(),
+           E = anticOut.end(); I != E; ++I)
+        if (!succAnticIn.test(VN.lookup(*I)))
+          temp.push_back(*I);
+
+      for (SmallVector<Value*, 16>::iterator I = temp.begin(), E = temp.end();
+           I != E; ++I) {
+        anticOut.erase(*I);
+        anticOut.reset(VN.lookup(*I));
+      }
+    }
+  }
+  
+  return false;
+}
+
+/// buildsets_anticin - Walk the postdom tree, calculating ANTIC_OUT for
+/// each block.  ANTIC_IN is then a function of ANTIC_OUT and the GEN
+/// sets populated in buildsets_availout
+unsigned GVNPRE::buildsets_anticin(BasicBlock* BB,
+                               ValueNumberedSet& anticOut,
+                               ValueNumberedSet& currExps,
+                               SmallPtrSet<Value*, 16>& currTemps,
+                               SmallPtrSet<BasicBlock*, 8>& visited) {
+  ValueNumberedSet& anticIn = anticipatedIn[BB];
+  unsigned old = anticIn.size();
+      
+  bool defer = buildsets_anticout(BB, anticOut, visited);
+  if (defer)
+    return 0;
+  
+  anticIn.clear();
+  
+  for (ValueNumberedSet::iterator I = anticOut.begin(),
+       E = anticOut.end(); I != E; ++I) {
+    anticIn.insert(*I);
+    anticIn.set(VN.lookup(*I));
+  }
+  for (ValueNumberedSet::iterator I = currExps.begin(),
+       E = currExps.end(); I != E; ++I) {
+    if (!anticIn.test(VN.lookup(*I))) {
+      anticIn.insert(*I);
+      anticIn.set(VN.lookup(*I));
+    }
+  } 
+  
+  for (SmallPtrSet<Value*, 16>::iterator I = currTemps.begin(),
+       E = currTemps.end(); I != E; ++I) {
+    anticIn.erase(*I);
+    anticIn.reset(VN.lookup(*I));
+  }
+  
+  clean(anticIn);
+  anticOut.clear();
+  
+  if (old != anticIn.size())
+    return 2;
+  else
+    return 1;
+}
+
+/// buildsets - Phase 1 of the main algorithm.  Construct the AVAIL_OUT
+/// and the ANTIC_IN sets.
+void GVNPRE::buildsets(Function& F) {
+  DenseMap<BasicBlock*, ValueNumberedSet> generatedExpressions;
+  DenseMap<BasicBlock*, SmallPtrSet<Value*, 16> > generatedTemporaries;
+
+  DominatorTree &DT = getAnalysis<DominatorTree>();   
+  
+  // Phase 1, Part 1: calculate AVAIL_OUT
+  
+  // Top-down walk of the dominator tree
+  for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
+         E = df_end(DT.getRootNode()); DI != E; ++DI) {
+    
+    // Get the sets to update for this block
+    ValueNumberedSet& currExps = generatedExpressions[DI->getBlock()];
+    ValueNumberedSet& currPhis = generatedPhis[DI->getBlock()];
+    SmallPtrSet<Value*, 16>& currTemps = generatedTemporaries[DI->getBlock()];
+    ValueNumberedSet& currAvail = availableOut[DI->getBlock()];     
+    
+    BasicBlock* BB = DI->getBlock();
+  
+    // A block inherits AVAIL_OUT from its dominator
+    if (DI->getIDom() != 0)
+      currAvail = availableOut[DI->getIDom()->getBlock()];
+
+    for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
+         BI != BE; ++BI)
+      buildsets_availout(BI, currAvail, currPhis, currExps,
+                         currTemps);
+      
+  }
+
+  // Phase 1, Part 2: calculate ANTIC_IN
+  
+  SmallPtrSet<BasicBlock*, 8> visited;
+  SmallPtrSet<BasicBlock*, 4> block_changed;
+  for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
+    block_changed.insert(FI);
+  
+  bool changed = true;
+  unsigned iterations = 0;
+  
+  while (changed) {
+    changed = false;
+    ValueNumberedSet anticOut;
+    
+    // Postorder walk of the CFG
+    for (po_iterator<BasicBlock*> BBI = po_begin(&F.getEntryBlock()),
+         BBE = po_end(&F.getEntryBlock()); BBI != BBE; ++BBI) {
+      BasicBlock* BB = *BBI;
+      
+      if (block_changed.count(BB) != 0) {
+        unsigned ret = buildsets_anticin(BB, anticOut,generatedExpressions[BB],
+                                         generatedTemporaries[BB], visited);
+      
+        if (ret == 0) {
+          changed = true;
+          continue;
+        } else {
+          visited.insert(BB);
+        
+          if (ret == 2)
+           for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
+                 PI != PE; ++PI) {
+              block_changed.insert(*PI);
+           }
+          else
+            block_changed.erase(BB);
+        
+          changed |= (ret == 2);
+        }
+      }
+    }
+    
+    iterations++;
+  }
+}
+
+/// insertion_pre - When a partial redundancy has been identified, eliminate it
+/// by inserting appropriate values into the predecessors and a phi node in
+/// the main block
+void GVNPRE::insertion_pre(Value* e, BasicBlock* BB,
+                           DenseMap<BasicBlock*, Value*>& avail,
+                    std::map<BasicBlock*, ValueNumberedSet>& new_sets) {
+  for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
+    Value* e2 = avail[*PI];
+    if (!availableOut[*PI].test(VN.lookup(e2))) {
+      User* U = cast<User>(e2);
+      
+      Value* s1 = 0;
+      if (isa<BinaryOperator>(U->getOperand(0)) || 
+          isa<CmpInst>(U->getOperand(0)) ||
+          isa<ShuffleVectorInst>(U->getOperand(0)) ||
+          isa<ExtractElementInst>(U->getOperand(0)) ||
+          isa<InsertElementInst>(U->getOperand(0)) ||
+          isa<SelectInst>(U->getOperand(0)) ||
+          isa<CastInst>(U->getOperand(0)) ||
+          isa<GetElementPtrInst>(U->getOperand(0)))
+        s1 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(0)));
+      else
+        s1 = U->getOperand(0);
+      
+      Value* s2 = 0;
+      
+      if (isa<BinaryOperator>(U) || 
+          isa<CmpInst>(U) ||
+          isa<ShuffleVectorInst>(U) ||
+          isa<ExtractElementInst>(U) ||
+          isa<InsertElementInst>(U) ||
+          isa<SelectInst>(U)) {
+        if (isa<BinaryOperator>(U->getOperand(1)) || 
+            isa<CmpInst>(U->getOperand(1)) ||
+            isa<ShuffleVectorInst>(U->getOperand(1)) ||
+            isa<ExtractElementInst>(U->getOperand(1)) ||
+            isa<InsertElementInst>(U->getOperand(1)) ||
+            isa<SelectInst>(U->getOperand(1)) ||
+            isa<CastInst>(U->getOperand(1)) ||
+            isa<GetElementPtrInst>(U->getOperand(1))) {
+          s2 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(1)));
+        } else {
+          s2 = U->getOperand(1);
+        }
+      }
+      
+      // Ternary Operators
+      Value* s3 = 0;
+      if (isa<ShuffleVectorInst>(U) ||
+          isa<InsertElementInst>(U) ||
+          isa<SelectInst>(U)) {
+        if (isa<BinaryOperator>(U->getOperand(2)) || 
+            isa<CmpInst>(U->getOperand(2)) ||
+            isa<ShuffleVectorInst>(U->getOperand(2)) ||
+            isa<ExtractElementInst>(U->getOperand(2)) ||
+            isa<InsertElementInst>(U->getOperand(2)) ||
+            isa<SelectInst>(U->getOperand(2)) ||
+            isa<CastInst>(U->getOperand(2)) ||
+            isa<GetElementPtrInst>(U->getOperand(2))) {
+          s3 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(2)));
+        } else {
+          s3 = U->getOperand(2);
+        }
+      }
+      
+      // Vararg operators
+      SmallVector<Value*, 4> sVarargs;
+      if (GetElementPtrInst* G = dyn_cast<GetElementPtrInst>(U)) {
+        for (GetElementPtrInst::op_iterator OI = G->idx_begin(),
+             OE = G->idx_end(); OI != OE; ++OI) {
+          if (isa<BinaryOperator>(*OI) || 
+              isa<CmpInst>(*OI) ||
+              isa<ShuffleVectorInst>(*OI) ||
+              isa<ExtractElementInst>(*OI) ||
+              isa<InsertElementInst>(*OI) ||
+              isa<SelectInst>(*OI) ||
+              isa<CastInst>(*OI) ||
+              isa<GetElementPtrInst>(*OI)) {
+            sVarargs.push_back(find_leader(availableOut[*PI], 
+                               VN.lookup(*OI)));
+          } else {
+            sVarargs.push_back(*OI);
+          }
+        }
+      }
+      
+      Value* newVal = 0;
+      if (BinaryOperator* BO = dyn_cast<BinaryOperator>(U))
+        newVal = BinaryOperator::Create(BO->getOpcode(), s1, s2,
+                                        BO->getName()+".gvnpre",
+                                        (*PI)->getTerminator());
+      else if (CmpInst* C = dyn_cast<CmpInst>(U))
+        newVal = CmpInst::Create(C->getOpcode(), C->getPredicate(), s1, s2,
+                                 C->getName()+".gvnpre", 
+                                 (*PI)->getTerminator());
+      else if (ShuffleVectorInst* S = dyn_cast<ShuffleVectorInst>(U))
+        newVal = new ShuffleVectorInst(s1, s2, s3, S->getName()+".gvnpre",
+                                       (*PI)->getTerminator());
+      else if (InsertElementInst* S = dyn_cast<InsertElementInst>(U))
+        newVal = InsertElementInst::Create(s1, s2, s3, S->getName()+".gvnpre",
+                                           (*PI)->getTerminator());
+      else if (ExtractElementInst* S = dyn_cast<ExtractElementInst>(U))
+        newVal = new ExtractElementInst(s1, s2, S->getName()+".gvnpre",
+                                        (*PI)->getTerminator());
+      else if (SelectInst* S = dyn_cast<SelectInst>(U))
+        newVal = SelectInst::Create(s1, s2, s3, S->getName()+".gvnpre",
+                                    (*PI)->getTerminator());
+      else if (CastInst* C = dyn_cast<CastInst>(U))
+        newVal = CastInst::Create(C->getOpcode(), s1, C->getType(),
+                                  C->getName()+".gvnpre", 
+                                  (*PI)->getTerminator());
+      else if (GetElementPtrInst* G = dyn_cast<GetElementPtrInst>(U))
+        newVal = GetElementPtrInst::Create(s1, sVarargs.begin(), sVarargs.end(),
+                                           G->getName()+".gvnpre", 
+                                           (*PI)->getTerminator());
+
+      VN.add(newVal, VN.lookup(U));
+                  
+      ValueNumberedSet& predAvail = availableOut[*PI];
+      val_replace(predAvail, newVal);
+      val_replace(new_sets[*PI], newVal);
+      predAvail.set(VN.lookup(newVal));
+            
+      DenseMap<BasicBlock*, Value*>::iterator av = avail.find(*PI);
+      if (av != avail.end())
+        avail.erase(av);
+      avail.insert(std::make_pair(*PI, newVal));
+                  
+      ++NumInsertedVals;
+    }
+  }
+              
+  PHINode* p = 0;
+              
+  for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
+    if (p == 0)
+      p = PHINode::Create(avail[*PI]->getType(), "gvnpre-join", BB->begin());
+    
+    p->addIncoming(avail[*PI], *PI);
+  }
+
+  VN.add(p, VN.lookup(e));
+  val_replace(availableOut[BB], p);
+  availableOut[BB].set(VN.lookup(e));
+  generatedPhis[BB].insert(p);
+  generatedPhis[BB].set(VN.lookup(e));
+  new_sets[BB].insert(p);
+  new_sets[BB].set(VN.lookup(e));
+              
+  ++NumInsertedPhis;
+}
+
+/// insertion_mergepoint - When walking the dom tree, check at each merge
+/// block for the possibility of a partial redundancy.  If present, eliminate it
+unsigned GVNPRE::insertion_mergepoint(SmallVector<Value*, 8>& workList,
+                                      df_iterator<DomTreeNode*>& D,
+                    std::map<BasicBlock*, ValueNumberedSet >& new_sets) {
+  bool changed_function = false;
+  bool new_stuff = false;
+  
+  BasicBlock* BB = D->getBlock();
+  for (unsigned i = 0; i < workList.size(); ++i) {
+    Value* e = workList[i];
+          
+    if (isa<BinaryOperator>(e) || isa<CmpInst>(e) ||
+        isa<ExtractElementInst>(e) || isa<InsertElementInst>(e) ||
+        isa<ShuffleVectorInst>(e) || isa<SelectInst>(e) || isa<CastInst>(e) ||
+        isa<GetElementPtrInst>(e)) {
+      if (availableOut[D->getIDom()->getBlock()].test(VN.lookup(e)))
+        continue;
+            
+      DenseMap<BasicBlock*, Value*> avail;
+      bool by_some = false;
+      bool all_same = true;
+      Value * first_s = 0;
+            
+      for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;
+           ++PI) {
+        Value *e2 = phi_translate(e, *PI, BB);
+        Value *e3 = find_leader(availableOut[*PI], VN.lookup(e2));
+              
+        if (e3 == 0) {
+          DenseMap<BasicBlock*, Value*>::iterator av = avail.find(*PI);
+          if (av != avail.end())
+            avail.erase(av);
+          avail.insert(std::make_pair(*PI, e2));
+          all_same = false;
+        } else {
+          DenseMap<BasicBlock*, Value*>::iterator av = avail.find(*PI);
+          if (av != avail.end())
+            avail.erase(av);
+          avail.insert(std::make_pair(*PI, e3));
+                
+          by_some = true;
+          if (first_s == 0)
+            first_s = e3;
+          else if (first_s != e3)
+            all_same = false;
+        }
+      }
+            
+      if (by_some && !all_same &&
+          !generatedPhis[BB].test(VN.lookup(e))) {
+        insertion_pre(e, BB, avail, new_sets);
+              
+        changed_function = true;
+        new_stuff = true;
+      }
+    }
+  }
+  
+  unsigned retval = 0;
+  if (changed_function)
+    retval += 1;
+  if (new_stuff)
+    retval += 2;
+  
+  return retval;
+}
+
+/// insert - Phase 2 of the main algorithm.  Walk the dominator tree looking for
+/// merge points.  When one is found, check for a partial redundancy.  If one is
+/// present, eliminate it.  Repeat this walk until no changes are made.
+bool GVNPRE::insertion(Function& F) {
+  bool changed_function = false;
+
+  DominatorTree &DT = getAnalysis<DominatorTree>();  
+  
+  std::map<BasicBlock*, ValueNumberedSet> new_sets;
+  bool new_stuff = true;
+  while (new_stuff) {
+    new_stuff = false;
+    for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
+         E = df_end(DT.getRootNode()); DI != E; ++DI) {
+      BasicBlock* BB = DI->getBlock();
+      
+      if (BB == 0)
+        continue;
+      
+      ValueNumberedSet& availOut = availableOut[BB];
+      ValueNumberedSet& anticIn = anticipatedIn[BB];
+      
+      // Replace leaders with leaders inherited from dominator
+      if (DI->getIDom() != 0) {
+        ValueNumberedSet& dom_set = new_sets[DI->getIDom()->getBlock()];
+        for (ValueNumberedSet::iterator I = dom_set.begin(),
+             E = dom_set.end(); I != E; ++I) {
+          val_replace(new_sets[BB], *I);
+          val_replace(availOut, *I);
+        }
+      }
+      
+      // If there is more than one predecessor...
+      if (pred_begin(BB) != pred_end(BB) && ++pred_begin(BB) != pred_end(BB)) {
+        SmallVector<Value*, 8> workList;
+        workList.reserve(anticIn.size());
+        topo_sort(anticIn, workList);
+        
+        unsigned result = insertion_mergepoint(workList, DI, new_sets);
+        if (result & 1)
+          changed_function = true;
+        if (result & 2)
+          new_stuff = true;
+      }
+    }
+  }
+  
+  return changed_function;
+}
+
+// GVNPRE::runOnFunction - This is the main transformation entry point for a
+// function.
+//
+bool GVNPRE::runOnFunction(Function &F) {
+  // Clean out global sets from any previous functions
+  VN.clear();
+  createdExpressions.clear();
+  availableOut.clear();
+  anticipatedIn.clear();
+  generatedPhis.clear();
+ 
+  bool changed_function = false;
+  
+  // Phase 1: BuildSets
+  // This phase calculates the AVAIL_OUT and ANTIC_IN sets
+  buildsets(F);
+  
+  // Phase 2: Insert
+  // This phase inserts values to make partially redundant values
+  // fully redundant
+  changed_function |= insertion(F);
+  
+  // Phase 3: Eliminate
+  // This phase performs trivial full redundancy elimination
+  changed_function |= elimination();
+  
+  // Phase 4: Cleanup
+  // This phase cleans up values that were created solely
+  // as leaders for expressions
+  cleanup();
+  
+  return changed_function;
+}