The CorrelatedExpressionElimination pass is known to be buggy. Remove it.

This fixes PR1769.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@46408 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 0 insertions, 1486 deletions

diff --git a/lib/Transforms/Scalar/CorrelatedExprs.cpp b/lib/Transforms/Scalar/CorrelatedExprs.cpp
deleted file mode 100644
index 9e1aa71e8b..0000000000
--- a/lib/Transforms/Scalar/CorrelatedExprs.cpp
+++ /dev/null
@@ -1,1486 +0,0 @@
-//===- CorrelatedExprs.cpp - Pass to detect and eliminated c.e.'s ---------===//
-//
-//                     The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// Correlated Expression Elimination propagates information from conditional
-// branches to blocks dominated by destinations of the branch.  It propagates
-// information from the condition check itself into the body of the branch,
-// allowing transformations like these for example:
-//
-//  if (i == 7)
-//    ... 4*i;  // constant propagation
-//
-//  M = i+1; N = j+1;
-//  if (i == j)
-//    X = M-N;  // = M-M == 0;
-//
-// This is called Correlated Expression Elimination because we eliminate or
-// simplify expressions that are correlated with the direction of a branch.  In
-// this way we use static information to give us some information about the
-// dynamic value of a variable.
-//
-//===----------------------------------------------------------------------===//
-
-#define DEBUG_TYPE "cee"
-#include "llvm/Transforms/Scalar.h"
-#include "llvm/Constants.h"
-#include "llvm/Pass.h"
-#include "llvm/Function.h"
-#include "llvm/Instructions.h"
-#include "llvm/Type.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Analysis/ConstantFolding.h"
-#include "llvm/Analysis/Dominators.h"
-#include "llvm/Assembly/Writer.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Support/CFG.h"
-#include "llvm/Support/Compiler.h"
-#include "llvm/Support/ConstantRange.h"
-#include "llvm/Support/Debug.h"
-#include "llvm/ADT/PostOrderIterator.h"
-#include "llvm/ADT/Statistic.h"
-#include <algorithm>
-using namespace llvm;
-
-STATISTIC(NumCmpRemoved, "Number of cmp instruction eliminated");
-STATISTIC(NumOperandsCann, "Number of operands canonicalized");
-STATISTIC(BranchRevectors, "Number of branches revectored");
-
-namespace {
-  class ValueInfo;
-  class VISIBILITY_HIDDEN Relation {
-    Value *Val;          // Relation to what value?
-    unsigned Rel;        // SetCC or ICmp relation, or Add if no information
-  public:
-    explicit Relation(Value *V) : Val(V), Rel(Instruction::Add) {}
-    bool operator<(const Relation &R) const { return Val < R.Val; }
-    Value *getValue() const { return Val; }
-    unsigned getRelation() const { return Rel; }
-
-    // contradicts - Return true if the relationship specified by the operand
-    // contradicts already known information.
-    //
-    bool contradicts(unsigned Rel, const ValueInfo &VI) const;
-
-    // incorporate - Incorporate information in the argument into this relation
-    // entry.  This assumes that the information doesn't contradict itself.  If
-    // any new information is gained, true is returned, otherwise false is
-    // returned to indicate that nothing was updated.
-    //
-    bool incorporate(unsigned Rel, ValueInfo &VI);
-
-    // KnownResult - Whether or not this condition determines the result of a
-    // setcc or icmp in the program.  False & True are intentionally 0 & 1 
-    // so we can convert to bool by casting after checking for unknown.
-    //
-    enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 };
-
-    // getImpliedResult - If this relationship between two values implies that
-    // the specified relationship is true or false, return that.  If we cannot
-    // determine the result required, return Unknown.
-    //
-    KnownResult getImpliedResult(unsigned Rel) const;
-
-    // print - Output this relation to the specified stream
-    void print(std::ostream &OS) const;
-    void dump() const;
-  };
-
-
-  // ValueInfo - One instance of this record exists for every value with
-  // relationships between other values.  It keeps track of all of the
-  // relationships to other values in the program (specified with Relation) that
-  // are known to be valid in a region.
-  //
-  class VISIBILITY_HIDDEN ValueInfo {
-    // RelationShips - this value is know to have the specified relationships to
-    // other values.  There can only be one entry per value, and this list is
-    // kept sorted by the Val field.
-    std::vector<Relation> Relationships;
-
-    // If information about this value is known or propagated from constant
-    // expressions, this range contains the possible values this value may hold.
-    ConstantRange Bounds;
-
-    // If we find that this value is equal to another value that has a lower
-    // rank, this value is used as it's replacement.
-    //
-    Value *Replacement;
-  public:
-    explicit ValueInfo(const Type *Ty)
-      : Bounds(Ty->isInteger() ? cast<IntegerType>(Ty)->getBitWidth()  : 32), 
-               Replacement(0) {}
-
-    // getBounds() - Return the constant bounds of the value...
-    const ConstantRange &getBounds() const { return Bounds; }
-    ConstantRange &getBounds() { return Bounds; }
-
-    const std::vector<Relation> &getRelationships() { return Relationships; }
-
-    // getReplacement - Return the value this value is to be replaced with if it
-    // exists, otherwise return null.
-    //
-    Value *getReplacement() const { return Replacement; }
-
-    // setReplacement - Used by the replacement calculation pass to figure out
-    // what to replace this value with, if anything.
-    //
-    void setReplacement(Value *Repl) { Replacement = Repl; }
-
-    // getRelation - return the relationship entry for the specified value.
-    // This can invalidate references to other Relations, so use it carefully.
-    //
-    Relation &getRelation(Value *V) {
-      // Binary search for V's entry...
-      std::vector<Relation>::iterator I =
-        std::lower_bound(Relationships.begin(), Relationships.end(),
-                         Relation(V));
-
-      // If we found the entry, return it...
-      if (I != Relationships.end() && I->getValue() == V)
-        return *I;
-
-      // Insert and return the new relationship...
-      return *Relationships.insert(I, Relation(V));
-    }
-
-    const Relation *requestRelation(Value *V) const {
-      // Binary search for V's entry...
-      std::vector<Relation>::const_iterator I =
-        std::lower_bound(Relationships.begin(), Relationships.end(),
-                         Relation(V));
-      if (I != Relationships.end() && I->getValue() == V)
-        return &*I;
-      return 0;
-    }
-
-    // print - Output information about this value relation...
-    void print(std::ostream &OS, Value *V) const;
-    void dump() const;
-  };
-
-  // RegionInfo - Keeps track of all of the value relationships for a region.  A
-  // region is the are dominated by a basic block.  RegionInfo's keep track of
-  // the RegionInfo for their dominator, because anything known in a dominator
-  // is known to be true in a dominated block as well.
-  //
-  class VISIBILITY_HIDDEN RegionInfo {
-    BasicBlock *BB;
-
-    // ValueMap - Tracks the ValueInformation known for this region
-    typedef std::map<Value*, ValueInfo> ValueMapTy;
-    ValueMapTy ValueMap;
-  public:
-    explicit RegionInfo(BasicBlock *bb) : BB(bb) {}
-
-    // getEntryBlock - Return the block that dominates all of the members of
-    // this region.
-    BasicBlock *getEntryBlock() const { return BB; }
-
-    // empty - return true if this region has no information known about it.
-    bool empty() const { return ValueMap.empty(); }
-
-    const RegionInfo &operator=(const RegionInfo &RI) {
-      ValueMap = RI.ValueMap;
-      return *this;
-    }
-
-    // print - Output information about this region...
-    void print(std::ostream &OS) const;
-    void dump() const;
-
-    // Allow external access.
-    typedef ValueMapTy::iterator iterator;
-    iterator begin() { return ValueMap.begin(); }
-    iterator end() { return ValueMap.end(); }
-
-    ValueInfo &getValueInfo(Value *V) {
-      ValueMapTy::iterator I = ValueMap.lower_bound(V);
-      if (I != ValueMap.end() && I->first == V) return I->second;
-      return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
-    }
-
-    const ValueInfo *requestValueInfo(Value *V) const {
-      ValueMapTy::const_iterator I = ValueMap.find(V);
-      if (I != ValueMap.end()) return &I->second;
-      return 0;
-    }
-
-    /// removeValueInfo - Remove anything known about V from our records.  This
-    /// works whether or not we know anything about V.
-    ///
-    void removeValueInfo(Value *V) {
-      ValueMap.erase(V);
-    }
-  };
-
-  /// CEE - Correlated Expression Elimination
-  class VISIBILITY_HIDDEN CEE : public FunctionPass {
-    std::map<Value*, unsigned> RankMap;
-    std::map<BasicBlock*, RegionInfo> RegionInfoMap;
-    DominatorTree *DT;
-  public:
-    static char ID; // Pass identification, replacement for typeid
-    CEE() : FunctionPass((intptr_t)&ID) {}
-
-    virtual bool runOnFunction(Function &F);
-
-    // We don't modify the program, so we preserve all analyses
-    virtual void getAnalysisUsage(AnalysisUsage &AU) const {
-      AU.addRequired<DominatorTree>();
-      AU.addRequiredID(BreakCriticalEdgesID);
-    };
-
-    // print - Implement the standard print form to print out analysis
-    // information.
-    virtual void print(std::ostream &O, const Module *M) const;
-
-  private:
-    RegionInfo &getRegionInfo(BasicBlock *BB) {
-      std::map<BasicBlock*, RegionInfo>::iterator I
-        = RegionInfoMap.lower_bound(BB);
-      if (I != RegionInfoMap.end() && I->first == BB) return I->second;
-      return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
-    }
-
-    void BuildRankMap(Function &F);
-    unsigned getRank(Value *V) const {
-      if (isa<Constant>(V)) return 0;
-      std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
-      if (I != RankMap.end()) return I->second;
-      return 0; // Must be some other global thing
-    }
-
-    bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
-
-    bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
-                                          RegionInfo &RI);
-
-    void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
-                            RegionInfo &RI);
-    void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
-                                    BasicBlock *RegionDominator);
-    void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
-                                   std::vector<BasicBlock*> &RegionExitBlocks);
-    void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
-                             const std::vector<BasicBlock*> &RegionExitBlocks);
-
-    void PropagateBranchInfo(BranchInst *BI);
-    void PropagateSwitchInfo(SwitchInst *SI);
-    void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
-    void PropagateRelation(unsigned Opcode, Value *Op0,
-                           Value *Op1, RegionInfo &RI);
-    void UpdateUsersOfValue(Value *V, RegionInfo &RI);
-    void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
-    void ComputeReplacements(RegionInfo &RI);
-
-    // getCmpResult - Given a icmp instruction, determine if the result is
-    // determined by facts we already know about the region under analysis.
-    // Return KnownTrue, KnownFalse, or UnKnown based on what we can determine.
-    Relation::KnownResult getCmpResult(CmpInst *ICI, const RegionInfo &RI);
-
-    bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
-    bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
-  };
-  
-  char CEE::ID = 0;
-  RegisterPass<CEE> X("cee", "Correlated Expression Elimination");
-}
-
-FunctionPass *llvm::createCorrelatedExpressionEliminationPass() {
-  return new CEE();
-}
-
-
-bool CEE::runOnFunction(Function &F) {
-  // Build a rank map for the function...
-  BuildRankMap(F);
-
-  // Traverse the dominator tree, computing information for each node in the
-  // tree.  Note that our traversal will not even touch unreachable basic
-  // blocks.
-  DT = &getAnalysis<DominatorTree>();
-
-  std::set<BasicBlock*> VisitedBlocks;
-  bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
-
-  RegionInfoMap.clear();
-  RankMap.clear();
-  return Changed;
-}
-
-// TransformRegion - Transform the region starting with BB according to the
-// calculated region information for the block.  Transforming the region
-// involves analyzing any information this block provides to successors,
-// propagating the information to successors, and finally transforming
-// successors.
-//
-// This method processes the function in depth first order, which guarantees
-// that we process the immediate dominator of a block before the block itself.
-// Because we are passing information from immediate dominators down to
-// dominatees, we obviously have to process the information source before the
-// information consumer.
-//
-bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
-  // Prevent infinite recursion...
-  if (VisitedBlocks.count(BB)) return false;
-  VisitedBlocks.insert(BB);
-
-  // Get the computed region information for this block...
-  RegionInfo &RI = getRegionInfo(BB);
-
-  // Compute the replacement information for this block...
-  ComputeReplacements(RI);
-
-  // If debugging, print computed region information...
-  DEBUG(RI.print(*cerr.stream()));
-
-  // Simplify the contents of this block...
-  bool Changed = SimplifyBasicBlock(*BB, RI);
-
-  // Get the terminator of this basic block...
-  TerminatorInst *TI = BB->getTerminator();
-
-  // Loop over all of the blocks that this block is the immediate dominator for.
-  // Because all information known in this region is also known in all of the
-  // blocks that are dominated by this one, we can safely propagate the
-  // information down now.
-  //
-  DomTreeNode *BBDom = DT->getNode(BB);
-  if (!RI.empty()) {     // Time opt: only propagate if we can change something
-    for (std::vector<DomTreeNode*>::iterator DI = BBDom->begin(),
-           E = BBDom->end(); DI != E; ++DI) {
-      BasicBlock *ChildBB = (*DI)->getBlock();
-      assert(RegionInfoMap.find(ChildBB) == RegionInfoMap.end() &&
-             "RegionInfo should be calculated in dominanace order!");
-      getRegionInfo(ChildBB) = RI;
-    }
-  }
-
-  // Now that all of our successors have information if they deserve it,
-  // propagate any information our terminator instruction finds to our
-  // successors.
-  if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
-    if (BI->isConditional())
-      PropagateBranchInfo(BI);
-  } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
-    PropagateSwitchInfo(SI);
-  }
-
-  // If this is a branch to a block outside our region that simply performs
-  // another conditional branch, one whose outcome is known inside of this
-  // region, then vector this outgoing edge directly to the known destination.
-  //
-  for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
-    while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
-      ++BranchRevectors;
-      Changed = true;
-    }
-
-  // Now that all of our successors have information, recursively process them.
-  for (std::vector<DomTreeNode*>::iterator DI = BBDom->begin(),
-         E = BBDom->end(); DI != E; ++DI) {
-    BasicBlock *ChildBB = (*DI)->getBlock();
-    Changed |= TransformRegion(ChildBB, VisitedBlocks);
-  }
-
-  return Changed;
-}
-
-// isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
-// revector the conditional branch in the bottom of the block, do so now.
-//
-static bool isBlockSimpleEnough(BasicBlock *BB) {
-  assert(isa<BranchInst>(BB->getTerminator()));
-  BranchInst *BI = cast<BranchInst>(BB->getTerminator());
-  assert(BI->isConditional());
-
-  // Check the common case first: empty block, or block with just a setcc.
-  if (BB->size() == 1 ||
-      (BB->size() == 2 && &BB->front() == BI->getCondition() &&
-       BI->getCondition()->hasOneUse()))
-    return true;
-
-  // Check the more complex case now...
-  BasicBlock::iterator I = BB->begin();
-
-  // FIXME: This should be reenabled once the regression with SIM is fixed!
-#if 0
-  // PHI Nodes are ok, just skip over them...
-  while (isa<PHINode>(*I)) ++I;
-#endif
-
-  // Accept the setcc instruction...
-  if (&*I == BI->getCondition())
-    ++I;
-
-  // Nothing else is acceptable here yet.  We must not revector... unless we are
-  // at the terminator instruction.
-  if (&*I == BI)
-    return true;
-
-  return false;
-}
-
-
-bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
-                                           RegionInfo &RI) {
-  // If this successor is a simple block not in the current region, which
-  // contains only a conditional branch, we decide if the outcome of the branch
-  // can be determined from information inside of the region.  Instead of going
-  // to this block, we can instead go to the destination we know is the right
-  // target.
-  //
-
-  // Check to see if we dominate the block. If so, this block will get the
-  // condition turned to a constant anyway.
-  //
-  //if (EF->dominates(RI.getEntryBlock(), BB))
-  // return 0;
-
-  BasicBlock *BB = TI->getParent();
-
-  // Get the destination block of this edge...
-  BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
-
-  // Make sure that the block ends with a conditional branch and is simple
-  // enough for use to be able to revector over.
-  BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
-  if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
-    return false;
-
-  // We can only forward the branch over the block if the block ends with a
-  // cmp we can determine the outcome for.
-  //
-  // FIXME: we can make this more generic.  Code below already handles more
-  // generic case.
-  if (!isa<CmpInst>(BI->getCondition()))
-    return false;
-
-  // Make a new RegionInfo structure so that we can simulate the effect of the
-  // PHI nodes in the block we are skipping over...
-  //
-  RegionInfo NewRI(RI);
-
-  // Remove value information for all of the values we are simulating... to make
-  // sure we don't have any stale information.
-  for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
-    if (I->getType() != Type::VoidTy)
-      NewRI.removeValueInfo(I);
-
-  // Put the newly discovered information into the RegionInfo...
-  for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
-    if (PHINode *PN = dyn_cast<PHINode>(I)) {
-      int OpNum = PN->getBasicBlockIndex(BB);
-      assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
-      PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
-    } else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
-      Relation::KnownResult Res = getCmpResult(CI, NewRI);
-      if (Res == Relation::Unknown) return false;
-      PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Res), NewRI);
-    } else {
-      assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
-    }
-
-  // Compute the facts implied by what we have discovered...
-  ComputeReplacements(NewRI);
-
-  ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
-  if (PredicateVI.getReplacement() &&
-      isa<Constant>(PredicateVI.getReplacement()) &&
-      !isa<GlobalValue>(PredicateVI.getReplacement())) {
-    ConstantInt *CB = cast<ConstantInt>(PredicateVI.getReplacement());
-
-    // Forward to the successor that corresponds to the branch we will take.
-    ForwardSuccessorTo(TI, SuccNo, 
-                       BI->getSuccessor(!CB->getZExtValue()), NewRI);
-    return true;
-  }
-
-  return false;
-}
-
-static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
-  if (const ValueInfo *VI = RI.requestValueInfo(V))
-    if (Value *Repl = VI->getReplacement())
-      return Repl;
-  return V;
-}
-
-/// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
-/// of Terminator 'TI' to the 'Dest' BasicBlock.  This method performs the
-/// mechanics of updating SSA information and revectoring the branch.
-///
-void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
-                             BasicBlock *Dest, RegionInfo &RI) {
-  // If there are any PHI nodes in the Dest BB, we must duplicate the entry
-  // in the PHI node for the old successor to now include an entry from the
-  // current basic block.
-  //
-  BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
-  BasicBlock *BB = TI->getParent();
-
-  DOUT << "Forwarding branch in basic block %" << BB->getName()
-       << " from block %" << OldSucc->getName() << " to block %"
-       << Dest->getName() << "\n"
-       << "Before forwarding: " << *BB->getParent();
-
-  // Because we know that there cannot be critical edges in the flow graph, and
-  // that OldSucc has multiple outgoing edges, this means that Dest cannot have
-  // multiple incoming edges.
-  //
-#ifndef NDEBUG
-  pred_iterator DPI = pred_begin(Dest); ++DPI;
-  assert(DPI == pred_end(Dest) && "Critical edge found!!");
-#endif
-
-  // Loop over any PHI nodes in the destination, eliminating them, because they
-  // may only have one input.
-  //
-  while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
-    assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
-    // Eliminate the PHI node
-    PN->replaceAllUsesWith(PN->getIncomingValue(0));
-    Dest->getInstList().erase(PN);
-  }
-
-  // If there are values defined in the "OldSucc" basic block, we need to insert
-  // PHI nodes in the regions we are dealing with to emulate them.  This can
-  // insert dead phi nodes, but it is more trouble to see if they are used than
-  // to just blindly insert them.
-  //
-  if (DT->dominates(OldSucc, Dest)) {
-    // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
-    // but have predecessors that are.  Additionally, prune down the set to only
-    // include blocks that are dominated by OldSucc as well.
-    //
-    std::vector<BasicBlock*> RegionExitBlocks;
-    CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
-
-    for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
-         I != E; ++I)
-      if (I->getType() != Type::VoidTy) {
-        // Create and insert the PHI node into the top of Dest.
-        PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
-                                     Dest->begin());
-        // There is definitely an edge from OldSucc... add the edge now
-        NewPN->addIncoming(I, OldSucc);
-
-        // There is also an edge from BB now, add the edge with the calculated
-        // value from the RI.
-        NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
-
-        // Make everything in the Dest region use the new PHI node now...
-        ReplaceUsesOfValueInRegion(I, NewPN, Dest);
-
-        // Make sure that exits out of the region dominated by NewPN get PHI
-        // nodes that merge the values as appropriate.
-        InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
-      }
-  }
-
-  // If there were PHI nodes in OldSucc, we need to remove the entry for this
-  // edge from the PHI node, and we need to replace any references to the PHI
-  // node with a new value.
-  //
-  for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
-    PHINode *PN = cast<PHINode>(I);
-
-    // Get the value flowing across the old edge and remove the PHI node entry
-    // for this edge: we are about to remove the edge!  Don't remove the PHI
-    // node yet though if this is the last edge into it.
-    Value *EdgeValue = PN->removeIncomingValue(BB, false);
-
-    // Make sure that anything that used to use PN now refers to EdgeValue
-    ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
-
-    // If there is only one value left coming into the PHI node, replace the PHI
-    // node itself with the one incoming value left.
-    //
-    if (PN->getNumIncomingValues() == 1) {
-      assert(PN->getNumIncomingValues() == 1);
-      PN->replaceAllUsesWith(PN->getIncomingValue(0));
-      PN->getParent()->getInstList().erase(PN);
-      I = OldSucc->begin();
-    } else if (PN->getNumIncomingValues() == 0) {  // Nuke the PHI
-      // If we removed the last incoming value to this PHI, nuke the PHI node
-      // now.
-      PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
-      PN->getParent()->getInstList().erase(PN);
-      I = OldSucc->begin();
-    } else {
-      ++I;  // Otherwise, move on to the next PHI node
-    }
-  }
-
-  // Actually revector the branch now...
-  TI->setSuccessor(SuccNo, Dest);
-
-  // If we just introduced a critical edge in the flow graph, make sure to break
-  // it right away...
-  SplitCriticalEdge(TI, SuccNo, this);
-
-  // Make sure that we don't introduce critical edges from oldsucc now!
-  for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
-       i != e; ++i)
-    SplitCriticalEdge(OldSucc->getTerminator(), i, this);
-
-  // Since we invalidated the CFG, recalculate the dominator set so that it is
-  // useful for later processing!
-  // FIXME: This is much worse than it really should be!
-  //EF->recalculate();
-
-  DOUT << "After forwarding: " << *BB->getParent();
-}
-
-/// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
-/// of New.  It only affects instructions that are defined in basic blocks that
-/// are dominated by Head.
-///
-void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
-                                     BasicBlock *RegionDominator) {
-  assert(Orig != New && "Cannot replace value with itself");
-  std::vector<Instruction*> InstsToChange;
-  std::vector<PHINode*>     PHIsToChange;
-  InstsToChange.reserve(Orig->getNumUses());
-
-  // Loop over instructions adding them to InstsToChange vector, this allows us
-  // an easy way to avoid invalidating the use_iterator at a bad time.
-  for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
-       I != E; ++I)
-    if (Instruction *User = dyn_cast<Instruction>(*I))
-      if (DT->dominates(RegionDominator, User->getParent()))
-        InstsToChange.push_back(User);
-      else if (PHINode *PN = dyn_cast<PHINode>(User)) {
-        PHIsToChange.push_back(PN);
-      }
-
-  // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
-  // dominated by orig.  If the block the value flows in from is dominated by
-  // RegionDominator, then we rewrite the PHI
-  for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
-    PHINode *PN = PHIsToChange[i];
-    for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
-      if (PN->getIncomingValue(j) == Orig &&
-          DT->dominates(RegionDominator, PN->getIncomingBlock(j)))
-        PN->setIncomingValue(j, New);
-  }
-
-  // Loop over the InstsToChange list, replacing all uses of Orig with uses of
-  // New.  This list contains all of the instructions in our region that use
-  // Orig.
-  for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
-    if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
-      // PHINodes must be handled carefully.  If the PHI node itself is in the
-      // region, we have to make sure to only do the replacement for incoming
-      // values that correspond to basic blocks in the region.
-      for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
-        if (PN->getIncomingValue(j) == Orig &&
-            DT->dominates(RegionDominator, PN->getIncomingBlock(j)))
-          PN->setIncomingValue(j, New);
-
-    } else {
-      InstsToChange[i]->replaceUsesOfWith(Orig, New);
-    }
-}
-
-static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
-                                 std::set<BasicBlock*> &Visited,
-                                 DominatorTree &DT,
-                                 std::vector<BasicBlock*> &RegionExitBlocks) {
-  if (Visited.count(BB)) return;
-  Visited.insert(BB);
-
-  if (DT.dominates(Header, BB)) {  // Block in the region, recursively traverse
-    for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
-      CalcRegionExitBlocks(Header, *I, Visited, DT, RegionExitBlocks);
-  } else {
-    // Header does not dominate this block, but we have a predecessor that does
-    // dominate us.  Add ourself to the list.
-    RegionExitBlocks.push_back(BB);
-  }
-}
-
-/// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
-/// BB, but have predecessors that are.  Additionally, prune down the set to
-/// only include blocks that are dominated by OldSucc as well.
-///
-void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
-                                    std::vector<BasicBlock*> &RegionExitBlocks){
-  std::set<BasicBlock*> Visited;  // Don't infinite loop
-
-  // Recursively calculate blocks we are interested in...
-  CalcRegionExitBlocks(BB, BB, Visited, *DT, RegionExitBlocks);
-
-  // Filter out blocks that are not dominated by OldSucc...
-  for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
-    if (DT->dominates(OldSucc, RegionExitBlocks[i]))
-      ++i;  // Block is ok, keep it.
-    else {
-      // Move to end of list...
-      std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
-      RegionExitBlocks.pop_back();        // Nuke the end
-    }
-  }
-}
-
-void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
-                             const std::vector<BasicBlock*> &RegionExitBlocks) {
-  assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
-  BasicBlock *BB = BBVal->getParent();
-
-  // Loop over all of the blocks we have to place PHIs in, doing it.
-  for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
-    BasicBlock *FBlock = RegionExitBlocks[i];  // Block on the frontier
-
-    // Create the new PHI node
-    PHINode *NewPN = new PHINode(BBVal->getType(),
-                                 OldVal->getName()+".fw_frontier",
-                                 FBlock->begin());
-
-    // Add an incoming value for every predecessor of the block...
-    for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
-         PI != PE; ++PI) {
-      // If the incoming edge is from the region dominated by BB, use BBVal,
-      // otherwise use OldVal.
-      NewPN->addIncoming(DT->dominates(BB, *PI) ? BBVal : OldVal, *PI);
-    }
-
-    // Now make everyone dominated by this block use this new value!
-    ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
-  }
-}
-
-
-
-// BuildRankMap - This method builds the rank map data structure which gives
-// each instruction/value in the function a value based on how early it appears
-// in the function.  We give constants and globals rank 0, arguments are
-// numbered starting at one, and instructions are numbered in reverse post-order
-// from where the arguments leave off.  This gives instructions in loops higher
-// values than instructions not in loops.
-//
-void CEE::BuildRankMap(Function &F) {
-  unsigned Rank = 1;  // Skip rank zero.
-
-  // Number the arguments...
-  for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
-    RankMap[I] = Rank++;
-
-  // Number the instructions in reverse post order...
-  ReversePostOrderTraversal<Function*> RPOT(&F);
-  for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
-         E = RPOT.end(); I != E; ++I)
-    for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
-         BBI != E; ++BBI)
-      if (BBI->getType() != Type::VoidTy)
-        RankMap[BBI] = Rank++;
-}
-
-
-// PropagateBranchInfo - When this method is invoked, we need to propagate
-// information derived from the branch condition into the true and false
-// branches of BI.  Since we know that there aren't any critical edges in the
-// flow graph, this can proceed unconditionally.
-//
-void CEE::PropagateBranchInfo(BranchInst *BI) {
-  assert(BI->isConditional() && "Must be a conditional branch!");
-
-  // Propagate information into the true block...
-  //
-  PropagateEquality(BI->getCondition(), ConstantInt::getTrue(),
-                    getRegionInfo(BI->getSuccessor(0)));
-
-  // Propagate information into the false block...
-  //
-  PropagateEquality(BI->getCondition(), ConstantInt::getFalse(),
-                    getRegionInfo(BI->getSuccessor(1)));
-}
-
-
-// PropagateSwitchInfo - We need to propagate the value tested by the
-// switch statement through each case block.
-//
-void CEE::PropagateSwitchInfo(SwitchInst *SI) {
-  // Propagate information down each of our non-default case labels.  We
-  // don't yet propagate information down the default label, because a
-  // potentially large number of inequality constraints provide less
-  // benefit per unit work than a single equality constraint.
-  //
-  Value *cond = SI->getCondition();
-  for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
-    PropagateEquality(cond, SI->getSuccessorValue(i),
-                      getRegionInfo(SI->getSuccessor(i)));
-}
-
-
-// PropagateEquality - If we discover that two values are equal to each other in
-// a specified region, propagate this knowledge recursively.
-//
-void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
-  if (Op0 == Op1) return;  // Gee whiz. Are these really equal each other?
-
-  if (isa<Constant>(Op0))  // Make sure the constant is always Op1
-    std::swap(Op0, Op1);
-
-  // Make sure we don't already know these are equal, to avoid infinite loops...
-  ValueInfo &VI = RI.getValueInfo(Op0);
-
-  // Get information about the known relationship between Op0 & Op1
-  Relation &KnownRelation = VI.getRelation(Op1);
-
-  // If we already know they're equal, don't reprocess...
-  if (KnownRelation.getRelation() == FCmpInst::FCMP_OEQ ||
-      KnownRelation.getRelation() == ICmpInst::ICMP_EQ)
-    return;
-
-  // If this is boolean, check to see if one of the operands is a constant.  If
-  // it's a constant, then see if the other one is one of a setcc instruction,
-  // an AND, OR, or XOR instruction.
-  //
-  ConstantInt *CB = dyn_cast<ConstantInt>(Op1);
-  if (CB && Op1->getType() == Type::Int1Ty) {
-    if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
-      // If we know that this instruction is an AND instruction, and the 
-      // result is true, this means that both operands to the OR are known 
-      // to be true as well.
-      //
-      if (CB->getZExtValue() && Inst->getOpcode() == Instruction::And) {
-        PropagateEquality(Inst->getOperand(0), CB, RI);
-        PropagateEquality(Inst->getOperand(1), CB, RI);
-      }
-
-      // If we know that this instruction is an OR instruction, and the result
-      // is false, this means that both operands to the OR are know to be 
-      // false as well.
-      //
-      if (!CB->getZExtValue() && Inst->getOpcode() == Instruction::Or) {
-        PropagateEquality(Inst->getOperand(0), CB, RI);
-        PropagateEquality(Inst->getOperand(1), CB, RI);
-      }
-
-      // If we know that this instruction is a NOT instruction, we know that 
-      // the operand is known to be the inverse of whatever the current 
-      // value is.
-      //
-      if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
-        if (BinaryOperator::isNot(BOp))
-          PropagateEquality(BinaryOperator::getNotArgument(BOp),
-                            ConstantInt::get(Type::Int1Ty, 
-                                             !CB->getZExtValue()), RI);
-
-      // If we know the value of a FCmp instruction, propagate the information
-      // about the relation into this region as well.
-      //
-      if (FCmpInst *FCI = dyn_cast<FCmpInst>(Inst)) {
-        if (CB->getZExtValue()) {  // If we know the condition is true...
-          // Propagate info about the LHS to the RHS & RHS to LHS
-          PropagateRelation(FCI->getPredicate(), FCI->getOperand(0),
-                            FCI->getOperand(1), RI);
-          PropagateRelation(FCI->getSwappedPredicate(),
-                            FCI->getOperand(1), FCI->getOperand(0), RI);
-
-        } else {               // If we know the condition is false...
-          // We know the opposite of the condition is true...
-          FCmpInst::Predicate C = FCI->getInversePredicate();
-
-          PropagateRelation(C, FCI->getOperand(0), FCI->getOperand(1), RI);
-          PropagateRelation(FCmpInst::getSwappedPredicate(C),
-                            FCI->getOperand(1), FCI->getOperand(0), RI);
-        }
-      }
-    
-      // If we know the value of a ICmp instruction, propagate the information
-      // about the relation into this region as well.
-      //
-      if (ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
-        if (CB->getZExtValue()) { // If we know the condition is true...
-          // Propagate info about the LHS to the RHS & RHS to LHS
-          PropagateRelation(ICI->getPredicate(), ICI->getOperand(0),
-                            ICI->getOperand(1), RI);
-          PropagateRelation(ICI->getSwappedPredicate(), ICI->getOperand(1),
-                            ICI->getOperand(1), RI);
-
-        } else {               // If we know the condition is false ...
-          // We know the opposite of the condition is true...
-          ICmpInst::Predicate C = ICI->getInversePredicate();
-
-          PropagateRelation(C, ICI->getOperand(0), ICI->getOperand(1), RI);
-          PropagateRelation(ICmpInst::getSwappedPredicate(C),
-                            ICI->getOperand(1), ICI->getOperand(0), RI);
-        }
-      }
-    }
-  }
-
-  // Propagate information about Op0 to Op1 & visa versa
-  PropagateRelation(ICmpInst::ICMP_EQ, Op0, Op1, RI);
-  PropagateRelation(ICmpInst::ICMP_EQ, Op1, Op0, RI);
-  PropagateRelation(FCmpInst::FCMP_OEQ, Op0, Op1, RI);
-  PropagateRelation(FCmpInst::FCMP_OEQ, Op1, Op0, RI);
-}
-
-
-// PropagateRelation - We know that the specified relation is true in all of the
-// blocks in the specified region.  Propagate the information about Op0 and
-// anything derived from it into this region.
-//
-void CEE::PropagateRelation(unsigned Opcode, Value *Op0,
-                            Value *Op1, RegionInfo &RI) {
-  assert(Op0->getType() == Op1->getType() && "Equal types expected!");
-
-  // Constants are already pretty well understood.  We will apply information
-  // about the constant to Op1 in another call to PropagateRelation.
-  //
-  if (isa<Constant>(Op0)) return;
-
-  // Get the region information for this block to update...
-  ValueInfo &VI = RI.getValueInfo(Op0);
-
-  // Get information about the known relationship between Op0 & Op1
-  Relation &Op1R = VI.getRelation(Op1);
-
-  // Quick bailout for common case if we are reprocessing an instruction...
-  if (Op1R.getRelation() == Opcode)
-    return;
-
-  // If we already have information that contradicts the current information we
-  // are propagating, ignore this info.  Something bad must have happened!
-  //
-  if (Op1R.contradicts(Opcode, VI)) {
-    Op1R.contradicts(Opcode, VI);
-    cerr << "Contradiction found for opcode: "
-         << ((isa<ICmpInst>(Op0)||isa<ICmpInst>(Op1)) ? 
-                  Instruction::getOpcodeName(Instruction::ICmp) :
-                  Instruction::getOpcodeName(Opcode))
-         << "\n";
-    Op1R.print(*cerr.stream());
-    return;
-  }
-
-  // If the information propagated is new, then we want process the uses of this
-  // instruction to propagate the information down to them.
-  //
-  if (Op1R.incorporate(Opcode, VI))
-    UpdateUsersOfValue(Op0, RI);
-}
-
-
-// UpdateUsersOfValue - The information about V in this region has been updated.
-// Propagate this to all consumers of the value.
-//
-void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
-  for (Value::use_iterator I = V->use_begin(), E = V->use_end();
-       I != E; ++I)
-    if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
-      // If this is an instruction using a value that we know something about,
-      // try to propagate information to the value produced by the
-      // instruction.  We can only do this if it is an instruction we can
-      // propagate information for (a setcc for example), and we only WANT to
-      // do this if the instruction dominates this region.
-      //
-      // If the instruction doesn't dominate this region, then it cannot be
-      // used in this region and we don't care about it.  If the instruction
-      // is IN this region, then we will simplify the instruction before we
-      // get to uses of it anyway, so there is no reason to bother with it
-      // here.  This check is also effectively checking to make sure that Inst
-      // is in the same function as our region (in case V is a global f.e.).
-      //
-      if (DT->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
-        IncorporateInstruction(Inst, RI);
-    }
-}
-
-// IncorporateInstruction - We just updated the information about one of the
-// operands to the specified instruction.  Update the information about the
-// value produced by this instruction
-//
-void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
-  if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
-    // See if we can figure out a result for this instruction...
-    Relation::KnownResult Result = getCmpResult(CI, RI);
-    if (Result != Relation::Unknown) {
-      PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Result != 0), RI);
-    }
-  }
-}
-
-
-// ComputeReplacements - Some values are known to be equal to other values in a
-// region.  For example if there is a comparison of equality between a variable
-// X and a constant C, we can replace all uses of X with C in the region we are
-// interested in.  We generalize this replacement to replace variables with
-// other variables if they are equal and there is a variable with lower rank
-// than the current one.  This offers a canonicalizing property that exposes
-// more redundancies for later transformations to take advantage of.
-//
-void CEE::ComputeReplacements(RegionInfo &RI) {
-  // Loop over all of the values in the region info map...
-  for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
-    ValueInfo &VI = I->second;
-
-    // If we know that this value is a particular constant, set Replacement to
-    // the constant...
-    Value *Replacement = 0;
-    const APInt * Rplcmnt = VI.getBounds().getSingleElement();
-    if (Rplcmnt)
-      Replacement = ConstantInt::get(*Rplcmnt);
-
-    // If this value is not known to be some constant, figure out the lowest
-    // rank value that it is known to be equal to (if anything).
-    //
-    if (Replacement == 0) {
-      // Find out if there are any equality relationships with values of lower
-      // rank than VI itself...
-      unsigned MinRank = getRank(I->first);
-
-      // Loop over the relationships known about Op0.
-      const std::vector<Relation> &Relationships = VI.getRelationships();
-      for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
-        if (Relationships[i].getRelation() == FCmpInst::FCMP_OEQ) {
-          unsigned R = getRank(Relationships[i].getValue());
-          if (R < MinRank) {
-            MinRank = R;
-            Replacement = Relationships[i].getValue();
-          }
-        }
-        else if (Relationships[i].getRelation() == ICmpInst::ICMP_EQ) {
-          unsigned R = getRank(Relationships[i].getValue());
-          if (R < MinRank) {
-            MinRank = R;
-            Replacement = Relationships[i].getValue();
-          }
-        }
-    }
-
-    // If we found something to replace this value with, keep track of it.
-    if (Replacement)
-      VI.setReplacement(Replacement);
-  }
-}
-
-// SimplifyBasicBlock - Given information about values in region RI, simplify
-// the instructions in the specified basic block.
-//
-bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
-  bool Changed = false;
-  for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
-    Instruction *Inst = I++;
-
-    // Convert instruction arguments to canonical forms...
-    Changed |= SimplifyInstruction(Inst, RI);
-
-    if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
-      // Try to simplify a setcc instruction based on inherited information
-      Relation::KnownResult Result = getCmpResult(CI, RI);
-      if (Result != Relation::Unknown) {
-        DEBUG(cerr << "Replacing icmp with " << Result
-                   << " constant: " << *CI);
-
-        CI->replaceAllUsesWith(ConstantInt::get(Type::Int1Ty, (bool)Result));
-        // The instruction is now dead, remove it from the program.
-        CI->getParent()->getInstList().erase(CI);
-        ++NumCmpRemoved;
-        Changed = true;
-      }
-    }
-  }
-
-  return Changed;
-}
-
-// SimplifyInstruction - Inspect the operands of the instruction, converting
-// them to their canonical form if possible.  This takes care of, for example,
-// replacing a value 'X' with a constant 'C' if the instruction in question is
-// dominated by a true seteq 'X', 'C'.
-//
-bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
-  bool Changed = false;
-
-  for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
-    if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
-      if (Value *Repl = VI->getReplacement()) {
-        // If we know if a replacement with lower rank than Op0, make the
-        // replacement now.
-        DOUT << "In Inst: " << *I << "  Replacing operand #" << i
-             << " with " << *Repl << "\n";
-        I->setOperand(i, Repl);
-        Changed = true;
-        ++NumOperandsCann;
-      }
-
-  return Changed;
-}
-
-// getCmpResult - Try to simplify a cmp instruction based on information
-// inherited from a dominating icmp instruction.  V is one of the operands to
-// the icmp instruction, and VI is the set of information known about it.  We
-// take two cases into consideration here.  If the comparison is against a
-// constant value, we can use the constant range to see if the comparison is
-// possible to succeed.  If it is not a comparison against a constant, we check
-// to see if there is a known relationship between the two values.  If so, we
-// may be able to eliminate the check.
-//
-Relation::KnownResult CEE::getCmpResult(CmpInst *CI,
-                                        const RegionInfo &RI) {
-  Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
-  unsigned short predicate = CI->getPredicate();
-
-  if (isa<Constant>(Op0)) {
-    if (isa<Constant>(Op1)) {
-      if (Constant *Result = ConstantFoldInstruction(CI)) {
-        // Wow, this is easy, directly eliminate the ICmpInst.
-        DEBUG(cerr << "Replacing cmp with constant fold: " << *CI);
-        return cast<ConstantInt>(Result)->getZExtValue()
-          ? Relation::KnownTrue : Relation::KnownFalse;
-      }
-    } else {
-      // We want to swap this instruction so that operand #0 is the constant.
-      std::swap(Op0, Op1);
-      if (isa<ICmpInst>(CI))
-        predicate = cast<ICmpInst>(CI)->getSwappedPredicate();
-      else
-        predicate = cast<FCmpInst>(CI)->getSwappedPredicate();
-    }
-  }
-
-  // Try to figure out what the result of this comparison will be...
-  Relation::KnownResult Result = Relation::Unknown;
-
-  // We have to know something about the relationship to prove anything...
-  if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
-
-    // At this point, we know that if we have a constant argument that it is in
-    // Op1.  Check to see if we know anything about comparing value with a
-    // constant, and if we can use this info to fold the icmp.
-    //
-    if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
-      // Check to see if we already know the result of this comparison...
-      ICmpInst::Predicate ipred = ICmpInst::Predicate(predicate);
-      ConstantRange R = ICmpInst::makeConstantRange(ipred, C->getValue());
-      ConstantRange Int = R.intersectWith(Op0VI->getBounds());
-
-      // If the intersection of the two ranges is empty, then the condition
-      // could never be true!
-      //
-      if (Int.isEmptySet()) {
-        Result = Relation::KnownFalse;
-
-      // Otherwise, if VI.getBounds() (the possible values) is a subset of R
-      // (the allowed values) then we know that the condition must always be
-      // true!
-      //
-      } else if (Int == Op0VI->getBounds()) {
-        Result = Relation::KnownTrue;
-      }
-    } else {
-      // If we are here, we know that the second argument is not a constant
-      // integral.  See if we know anything about Op0 & Op1 that allows us to
-      // fold this anyway.
-      //
-      // Do we have value information about Op0 and a relation to Op1?
-      if (const Relation *Op2R = Op0VI->requestRelation(Op1))
-        Result = Op2R->getImpliedResult(predicate);
-    }
-  }
-  return Result;
-}
-
-//===----------------------------------------------------------------------===//
-//  Relation Implementation
-//===----------------------------------------------------------------------===//
-
-// contradicts - Return true if the relationship specified by the operand
-// contradicts already known information.
-//
-bool Relation::contradicts(unsigned Op,
-                           const ValueInfo &VI) const {
-  assert (Op != Instruction::Add && "Invalid relation argument!");
-
-  // If this is a relationship with a constant, make sure that this relationship
-  // does not contradict properties known about the bounds of the constant.
-  //
-  if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
-    if (Op >= ICmpInst::FIRST_ICMP_PREDICATE && 
-        Op <= ICmpInst::LAST_ICMP_PREDICATE) {
-      ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
-      if (ICmpInst::makeConstantRange(ipred, C->getValue())
-                    .intersectWith(VI.getBounds()).isEmptySet())
-        return true;
-    }
-
-  switch (Rel) {
-  default: assert(0 && "Unknown Relationship code!");
-  case Instruction::Add: return false;  // Nothing known, nothing contradicts
-  case ICmpInst::ICMP_EQ:
-    return Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
-           Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT ||
-           Op == ICmpInst::ICMP_NE;
-  case ICmpInst::ICMP_NE:  return Op == ICmpInst::ICMP_EQ;
-  case ICmpInst::ICMP_ULE:
-  case ICmpInst::ICMP_SLE: return Op == ICmpInst::ICMP_UGT ||
-                                  Op == ICmpInst::ICMP_SGT;
-  case ICmpInst::ICMP_UGE:
-  case ICmpInst::ICMP_SGE: return Op == ICmpInst::ICMP_ULT ||
-                                  Op == ICmpInst::ICMP_SLT;
-  case ICmpInst::ICMP_ULT:
-  case ICmpInst::ICMP_SLT:
-    return Op == ICmpInst::ICMP_EQ  || Op == ICmpInst::ICMP_UGT ||
-           Op == ICmpInst::ICMP_SGT || Op == ICmpInst::ICMP_UGE ||
-           Op == ICmpInst::ICMP_SGE;
-  case ICmpInst::ICMP_UGT:
-  case ICmpInst::ICMP_SGT:
-    return Op == ICmpInst::ICMP_EQ  || Op == ICmpInst::ICMP_ULT ||
-           Op == ICmpInst::ICMP_SLT || Op == ICmpInst::ICMP_ULE ||
-           Op == ICmpInst::ICMP_SLE;
-  case FCmpInst::FCMP_OEQ:
-    return Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT ||
-           Op == FCmpInst::FCMP_ONE;
-  case FCmpInst::FCMP_ONE: return Op == FCmpInst::FCMP_OEQ;
-  case FCmpInst::FCMP_OLE: return Op == FCmpInst::FCMP_OGT;
-  case FCmpInst::FCMP_OGE: return Op == FCmpInst::FCMP_OLT;
-  case FCmpInst::FCMP_OLT:
-    return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT ||
-           Op == FCmpInst::FCMP_OGE;
-  case FCmpInst::FCMP_OGT:
-    return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT ||
-           Op == FCmpInst::FCMP_OLE;
-  }
-}
-
-// incorporate - Incorporate information in the argument into this relation
-// entry.  This assumes that the information doesn't contradict itself.  If any
-// new information is gained, true is returned, otherwise false is returned to
-// indicate that nothing was updated.
-//
-bool Relation::incorporate(unsigned Op, ValueInfo &VI) {
-  assert(!contradicts(Op, VI) &&
-         "Cannot incorporate contradictory information!");
-
-  // If this is a relationship with a constant, make sure that we update the
-  // range that is possible for the value to have...
-  //
-  if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
-    if (Op >= ICmpInst::FIRST_ICMP_PREDICATE && 
-        Op <= ICmpInst::LAST_ICMP_PREDICATE) {
-      ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
-      VI.getBounds() = 
-        ICmpInst::makeConstantRange(ipred, C->getValue())
-                  .intersectWith(VI.getBounds());
-    }
-
-  switch (Rel) {
-  default: assert(0 && "Unknown prior value!");
-  case Instruction::Add:   Rel = Op; return true;
-  case ICmpInst::ICMP_EQ:
-  case ICmpInst::ICMP_NE:
-  case ICmpInst::ICMP_ULT:
-  case ICmpInst::ICMP_SLT:
-  case ICmpInst::ICMP_UGT:
-  case ICmpInst::ICMP_SGT: return false;  // Nothing is more precise
-  case ICmpInst::ICMP_ULE:
-  case ICmpInst::ICMP_SLE:
-    if (Op == ICmpInst::ICMP_EQ  || Op == ICmpInst::ICMP_ULT ||
-        Op == ICmpInst::ICMP_SLT) {
-      Rel = Op;
-      return true;
-    } else if (Op == ICmpInst::ICMP_NE) {
-      Rel = Rel == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_ULT :
-            ICmpInst::ICMP_SLT;
-      return true;
-    }
-    return false;
-  case ICmpInst::ICMP_UGE:
-  case ICmpInst::ICMP_SGE:
-    if (Op == ICmpInst::ICMP_EQ  || ICmpInst::ICMP_UGT ||
-        Op == ICmpInst::ICMP_SGT) {
-      Rel = Op;
-      return true;
-    } else if (Op == ICmpInst::ICMP_NE) {
-      Rel = Rel == ICmpInst::ICMP_UGE ? ICmpInst::ICMP_UGT :
-            ICmpInst::ICMP_SGT;
-      return true;
-    }
-    return false;
-  case FCmpInst::FCMP_OEQ: return false;  // Nothing is more precise
-  case FCmpInst::FCMP_ONE: return false;  // Nothing is more precise
-  case FCmpInst::FCMP_OLT: return false;  // Nothing is more precise
-  case FCmpInst::FCMP_OGT: return false;  // Nothing is more precise
-  case FCmpInst::FCMP_OLE:
-    if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT) {
-      Rel = Op;
-      return true;
-    } else if (Op == FCmpInst::FCMP_ONE) {
-      Rel = FCmpInst::FCMP_OLT;
-      return true;
-    }
-    return false;
-  case FCmpInst::FCMP_OGE: 
-    if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT) {
-      Rel = Op;
-      return true;
-    } else if (Op == FCmpInst::FCMP_ONE) {
-      Rel = FCmpInst::FCMP_OGT;
-      return true;
-    }
-    return false;
-  }
-}
-
-// getImpliedResult - If this relationship between two values implies that
-// the specified relationship is true or false, return that.  If we cannot
-// determine the result required, return Unknown.
-//
-Relation::KnownResult
-Relation::getImpliedResult(unsigned Op) const {
-  if (Rel == Op) return KnownTrue;
-  if (Op >= ICmpInst::FIRST_ICMP_PREDICATE && 
-      Op <= ICmpInst::LAST_ICMP_PREDICATE) {
-    if (Rel == unsigned(ICmpInst::getInversePredicate(ICmpInst::Predicate(Op))))
-      return KnownFalse;
-  } else if (Op <= FCmpInst::LAST_FCMP_PREDICATE) {
-    if (Rel == unsigned(FCmpInst::getInversePredicate(FCmpInst::Predicate(Op))))
-    return KnownFalse;
-  }
-
-  switch (Rel) {
-  default: assert(0 && "Unknown prior value!");
-  case ICmpInst::ICMP_EQ:
-    if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE || 
-        Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE) return KnownTrue;
-    if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT || 
-        Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT) return KnownFalse;
-    break;
-  case ICmpInst::ICMP_ULT:
-  case ICmpInst::ICMP_SLT:
-    if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
-        Op == ICmpInst::ICMP_NE) return KnownTrue;
-    if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
-    break;
-  case ICmpInst::ICMP_UGT:
-  case ICmpInst::ICMP_SGT:
-    if (Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE ||
-        Op == ICmpInst::ICMP_NE) return KnownTrue;
-    if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
-    break;
-  case FCmpInst::FCMP_OEQ:
-    if (Op == FCmpInst::FCMP_OLE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
-    if (Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT) return KnownFalse;
-    break;
-  case FCmpInst::FCMP_OLT:
-    if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OLE) return KnownTrue;
-    if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
-    break;
-  case FCmpInst::FCMP_OGT:
-    if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
-    if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
-    break;
-  case ICmpInst::ICMP_NE:
-  case ICmpInst::ICMP_SLE:
-  case ICmpInst::ICMP_ULE:
-  case ICmpInst::ICMP_UGE:
-  case ICmpInst::ICMP_SGE:
-  case FCmpInst::FCMP_ONE:
-  case FCmpInst::FCMP_OLE:
-  case FCmpInst::FCMP_OGE:
-  case FCmpInst::FCMP_FALSE:
-  case FCmpInst::FCMP_ORD:
-  case FCmpInst::FCMP_UNO:
-  case FCmpInst::FCMP_UEQ:
-  case FCmpInst::FCMP_UGT:
-  case FCmpInst::FCMP_UGE:
-  case FCmpInst::FCMP_ULT:
-  case FCmpInst::FCMP_ULE:
-  case FCmpInst::FCMP_UNE:
-  case FCmpInst::FCMP_TRUE:
-    break;
-  }
-  return Unknown;
-}
-
-
-//===----------------------------------------------------------------------===//
-// Printing Support...
-//===----------------------------------------------------------------------===//
-
-// print - Implement the standard print form to print out analysis information.
-void CEE::print(std::ostream &O, const Module *M) const {
-  O << "\nPrinting Correlated Expression Info:\n";
-  for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
-         RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
-    I->second.print(O);
-}
-
-// print - Output information about this region...
-void RegionInfo::print(std::ostream &OS) const {
-  if (ValueMap.empty()) return;
-
-  OS << " RegionInfo for basic block: " << BB->getName() << "\n";
-  for (std::map<Value*, ValueInfo>::const_iterator
-         I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
-    I->second.print(OS, I->first);
-  OS << "\n";
-}
-
-// print - Output information about this value relation...
-void ValueInfo::print(std::ostream &OS, Value *V) const {
-  if (Relationships.empty()) return;
-
-  if (V) {
-    OS << "  ValueInfo for: ";
-    WriteAsOperand(OS, V);
-  }
-  OS << "\n    Bounds = " << Bounds << "\n";
-  if (Replacement) {
-    OS << "    Replacement = ";
-    WriteAsOperand(OS, Replacement);
-    OS << "\n";
-  }
-  for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
-    Relationships[i].print(OS);
-}
-
-// print - Output this relation to the specified stream
-void Relation::print(std::ostream &OS) const {
-  OS << "    is ";
-  switch (Rel) {
-  default:           OS << "*UNKNOWN*"; break;
-  case ICmpInst::ICMP_EQ:
-  case FCmpInst::FCMP_ORD:
-  case FCmpInst::FCMP_UEQ:
-  case FCmpInst::FCMP_OEQ: OS << "== "; break;
-  case ICmpInst::ICMP_NE:
-  case FCmpInst::FCMP_UNO:
-  case FCmpInst::FCMP_UNE:
-  case FCmpInst::FCMP_ONE: OS << "!= "; break;
-  case ICmpInst::ICMP_ULT:
-  case ICmpInst::ICMP_SLT:
-  case FCmpInst::FCMP_ULT:
-  case FCmpInst::FCMP_OLT: OS << "< "; break;
-  case ICmpInst::ICMP_UGT:
-  case ICmpInst::ICMP_SGT:
-  case FCmpInst::FCMP_UGT:
-  case FCmpInst::FCMP_OGT: OS << "> "; break;
-  case ICmpInst::ICMP_ULE:
-  case ICmpInst::ICMP_SLE:
-  case FCmpInst::FCMP_ULE:
-  case FCmpInst::FCMP_OLE: OS << "<= "; break;
-  case ICmpInst::ICMP_UGE:
-  case ICmpInst::ICMP_SGE:
-  case FCmpInst::FCMP_UGE:
-  case FCmpInst::FCMP_OGE: OS << ">= "; break;
-  }
-
-  WriteAsOperand(OS, Val);
-  OS << "\n";
-}
-
-// Don't inline these methods or else we won't be able to call them from GDB!
-void Relation::dump() const { print(*cerr.stream()); }
-void ValueInfo::dump() const { print(*cerr.stream(), 0); }
-void RegionInfo::dump() const { print(*cerr.stream()); }