utils/TableGen/DAGISelEmitter.cpp

//===- DAGISelEmitter.cpp - Generate an instruction selector --------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This tablegen backend emits a DAG instruction selector.
//
//===----------------------------------------------------------------------===//

#include "DAGISelEmitter.h"
#include "Record.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Debug.h"
#include <algorithm>
#include <deque>
#include <iostream>
using namespace llvm;

static cl::opt<bool>
GenDebug("gen-debug", cl::desc("Generate debug code"), cl::init(false));

//===----------------------------------------------------------------------===//
// DAGISelEmitter Helper methods
//

/// getNodeName - The top level Select_* functions have an "SDNode* N"
/// argument. When expanding the pattern-matching code, the intermediate
/// variables have type SDValue. This function provides a uniform way to
/// reference the underlying "SDNode *" for both cases.
static std::string getNodeName(const std::string &S) {
  if (S == "N") return S;
  return S + ".getNode()";
}

/// getNodeValue - Similar to getNodeName, except it provides a uniform
/// way to access the SDValue for both cases.
static std::string getValueName(const std::string &S) {
  if (S == "N") return "SDValue(N, 0)";
  return S;
}

/// NodeIsComplexPattern - return true if N is a leaf node and a subclass of
/// ComplexPattern.
static bool NodeIsComplexPattern(TreePatternNode *N) {
  return (N->isLeaf() &&
          dynamic_cast<DefInit*>(N->getLeafValue()) &&
          static_cast<DefInit*>(N->getLeafValue())->getDef()->
          isSubClassOf("ComplexPattern"));
}

/// NodeGetComplexPattern - return the pointer to the ComplexPattern if N
/// is a leaf node and a subclass of ComplexPattern, else it returns NULL.
static const ComplexPattern *NodeGetComplexPattern(TreePatternNode *N,
                                                   CodeGenDAGPatterns &CGP) {
  if (N->isLeaf() &&
      dynamic_cast<DefInit*>(N->getLeafValue()) &&
      static_cast<DefInit*>(N->getLeafValue())->getDef()->
      isSubClassOf("ComplexPattern")) {
    return &CGP.getComplexPattern(static_cast<DefInit*>(N->getLeafValue())
                                       ->getDef());
  }
  return NULL;
}

/// getPatternSize - Return the 'size' of this pattern.  We want to match large
/// patterns before small ones.  This is used to determine the size of a
/// pattern.
static unsigned getPatternSize(TreePatternNode *P, CodeGenDAGPatterns &CGP) {
  assert((EEVT::isExtIntegerInVTs(P->getExtTypes()) ||
          EEVT::isExtFloatingPointInVTs(P->getExtTypes()) ||
          P->getExtTypeNum(0) == MVT::isVoid ||
          P->getExtTypeNum(0) == MVT::Flag ||
          P->getExtTypeNum(0) == MVT::iPTR ||
          P->getExtTypeNum(0) == MVT::iPTRAny) && 
         "Not a valid pattern node to size!");
  unsigned Size = 3;  // The node itself.
  // If the root node is a ConstantSDNode, increases its size.
  // e.g. (set R32:$dst, 0).
  if (P->isLeaf() && dynamic_cast<IntInit*>(P->getLeafValue()))
    Size += 2;

  // FIXME: This is a hack to statically increase the priority of patterns
  // which maps a sub-dag to a complex pattern. e.g. favors LEA over ADD.
  // Later we can allow complexity / cost for each pattern to be (optionally)
  // specified. To get best possible pattern match we'll need to dynamically
  // calculate the complexity of all patterns a dag can potentially map to.
  const ComplexPattern *AM = NodeGetComplexPattern(P, CGP);
  if (AM)
    Size += AM->getNumOperands() * 3;

  // If this node has some predicate function that must match, it adds to the
  // complexity of this node.
  if (!P->getPredicateFns().empty())
    ++Size;
  
  // Count children in the count if they are also nodes.
  for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i) {
    TreePatternNode *Child = P->getChild(i);
    if (!Child->isLeaf() && Child->getExtTypeNum(0) != MVT::Other)
      Size += getPatternSize(Child, CGP);
    else if (Child->isLeaf()) {
      if (dynamic_cast<IntInit*>(Child->getLeafValue())) 
        Size += 5;  // Matches a ConstantSDNode (+3) and a specific value (+2).
      else if (NodeIsComplexPattern(Child))
        Size += getPatternSize(Child, CGP);
      else if (!Child->getPredicateFns().empty())
        ++Size;
    }
  }
  
  return Size;
}

/// getResultPatternCost - Compute the number of instructions for this pattern.
/// This is a temporary hack.  We should really include the instruction
/// latencies in this calculation.
static unsigned getResultPatternCost(TreePatternNode *P,
                                     CodeGenDAGPatterns &CGP) {
  if (P->isLeaf()) return 0;
  
  unsigned Cost = 0;
  Record *Op = P->getOperator();
  if (Op->isSubClassOf("Instruction")) {
    Cost++;
    CodeGenInstruction &II = CGP.getTargetInfo().getInstruction(Op->getName());
    if (II.usesCustomInserter)
      Cost += 10;
  }
  for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
    Cost += getResultPatternCost(P->getChild(i), CGP);
  return Cost;
}

/// getResultPatternCodeSize - Compute the code size of instructions for this
/// pattern.
static unsigned getResultPatternSize(TreePatternNode *P, 
                                     CodeGenDAGPatterns &CGP) {
  if (P->isLeaf()) return 0;

  unsigned Cost = 0;
  Record *Op = P->getOperator();
  if (Op->isSubClassOf("Instruction")) {
    Cost += Op->getValueAsInt("CodeSize");
  }
  for (unsigned i = 0, e = P->getNumChildren(); i != e; ++i)
    Cost += getResultPatternSize(P->getChild(i), CGP);
  return Cost;
}

// PatternSortingPredicate - return true if we prefer to match LHS before RHS.
// In particular, we want to match maximal patterns first and lowest cost within
// a particular complexity first.
struct PatternSortingPredicate {
  PatternSortingPredicate(CodeGenDAGPatterns &cgp) : CGP(cgp) {}
  CodeGenDAGPatterns &CGP;

  typedef std::pair<unsigned, std::string> CodeLine;
  typedef std::vector<CodeLine> CodeList;
  typedef std::vector<std::pair<const PatternToMatch*, CodeList> > PatternList;

  bool operator()(const std::pair<const PatternToMatch*, CodeList> &LHSPair,
                  const std::pair<const PatternToMatch*, CodeList> &RHSPair) {
    const PatternToMatch *LHS = LHSPair.first;
    const PatternToMatch *RHS = RHSPair.first;

    unsigned LHSSize = getPatternSize(LHS->getSrcPattern(), CGP);
    unsigned RHSSize = getPatternSize(RHS->getSrcPattern(), CGP);
    LHSSize += LHS->getAddedComplexity();
    RHSSize += RHS->getAddedComplexity();
    if (LHSSize > RHSSize) return true;   // LHS -> bigger -> less cost
    if (LHSSize < RHSSize) return false;
    
    // If the patterns have equal complexity, compare generated instruction cost
    unsigned LHSCost = getResultPatternCost(LHS->getDstPattern(), CGP);
    unsigned RHSCost = getResultPatternCost(RHS->getDstPattern(), CGP);
    if (LHSCost < RHSCost) return true;
    if (LHSCost > RHSCost) return false;

    return getResultPatternSize(LHS->getDstPattern(), CGP) <
      getResultPatternSize(RHS->getDstPattern(), CGP);
  }
};

/// getRegisterValueType - Look up and return the ValueType of the specified
/// register. If the register is a member of multiple register classes which
/// have different associated types, return MVT::Other.
static MVT::SimpleValueType getRegisterValueType(Record *R, const CodeGenTarget &T) {
  bool FoundRC = false;
  MVT::SimpleValueType VT = MVT::Other;
  const std::vector<CodeGenRegisterClass> &RCs = T.getRegisterClasses();
  std::vector<CodeGenRegisterClass>::const_iterator RC;
  std::vector<Record*>::const_iterator Element;

  for (RC = RCs.begin() ; RC != RCs.end() ; RC++) {
    Element = find((*RC).Elements.begin(), (*RC).Elements.end(), R);
    if (Element != (*RC).Elements.end()) {
      if (!FoundRC) {
        FoundRC = true;
        VT = (*RC).getValueTypeNum(0);
      } else {
        // In multiple RC's
        if (VT != (*RC).getValueTypeNum(0)) {
          // Types of the RC's do not agree. Return MVT::Other. The
          // target is responsible for handling this.
          return MVT::Other;
        }
      }
    }
  }
  return VT;
}


/// RemoveAllTypes - A quick recursive walk over a pattern which removes all
/// type information from it.
static void RemoveAllTypes(TreePatternNode *N) {
  N->removeTypes();
  if (!N->isLeaf())
    for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i)
      RemoveAllTypes(N->getChild(i));
}

/// NodeHasProperty - return true if TreePatternNode has the specified
/// property.
static bool NodeHasProperty(TreePatternNode *N, SDNP Property,
                            CodeGenDAGPatterns &CGP) {
  if (N->isLeaf()) {
    const ComplexPattern *CP = NodeGetComplexPattern(N, CGP);
    if (CP)
      return CP->hasProperty(Property);
    return false;
  }
  Record *Operator = N->getOperator();
  if (!Operator->isSubClassOf("SDNode")) return false;

  return CGP.getSDNodeInfo(Operator).hasProperty(Property);
}

static bool PatternHasProperty(TreePatternNode *N, SDNP Property,
                               CodeGenDAGPatterns &CGP) {
  if (NodeHasProperty(N, Property, CGP))
    return true;

  for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i) {
    TreePatternNode *Child = N->getChild(i);
    if (PatternHasProperty(Child, Property, CGP))
      return true;
  }

  return false;
}

static std::string getOpcodeName(Record *Op, CodeGenDAGPatterns &CGP) {
  return CGP.getSDNodeInfo(Op).getEnumName();
}

//===----------------------------------------------------------------------===//
// Node Transformation emitter implementation.
//
void DAGISelEmitter::EmitNodeTransforms(raw_ostream &OS) {
  // Walk the pattern fragments, adding them to a map, which sorts them by
  // name.
  typedef std::map<std::string, CodeGenDAGPatterns::NodeXForm> NXsByNameTy;
  NXsByNameTy NXsByName;

  for (CodeGenDAGPatterns::nx_iterator I = CGP.nx_begin(), E = CGP.nx_end();
       I != E; ++I)
    NXsByName.insert(std::make_pair(I->first->getName(), I->second));
  
  OS << "\n// Node transformations.\n";
  
  for (NXsByNameTy::iterator I = NXsByName.begin(), E = NXsByName.end();
       I != E; ++I) {
    Record *SDNode = I->second.first;
    std::string Code = I->second.second;
    
    if (Code.empty()) continue;  // Empty code?  Skip it.
    
    std::string ClassName = CGP.getSDNodeInfo(SDNode).getSDClassName();
    const char *C2 = ClassName == "SDNode" ? "N" : "inN";
    
    OS << "inline SDValue Transform_" << I->first << "(SDNode *" << C2
       << ") {\n";
    if (ClassName != "SDNode")
      OS << "  " << ClassName << " *N = cast<" << ClassName << ">(inN);\n";
    OS << Code << "\n}\n";
  }
}

//===----------------------------------------------------------------------===//
// Predicate emitter implementation.
//

void DAGISelEmitter::EmitPredicateFunctions(raw_ostream &OS) {
  OS << "\n// Predicate functions.\n";

  // Walk the pattern fragments, adding them to a map, which sorts them by
  // name.
  typedef std::map<std::string, std::pair<Record*, TreePattern*> > PFsByNameTy;
  PFsByNameTy PFsByName;

  for (CodeGenDAGPatterns::pf_iterator I = CGP.pf_begin(), E = CGP.pf_end();
       I != E; ++I)
    PFsByName.insert(std::make_pair(I->first->getName(), *I));

  
  for (PFsByNameTy::iterator I = PFsByName.begin(), E = PFsByName.end();
       I != E; ++I) {
    Record *PatFragRecord = I->second.first;// Record that derives from PatFrag.
    TreePattern *P = I->second.second;
    
    // If there is a code init for this fragment, emit the predicate code.
    std::string Code = PatFragRecord->getValueAsCode("Predicate");
    if (Code.empty()) continue;
    
    if (P->getOnlyTree()->isLeaf())
      OS << "inline bool Predicate_" << PatFragRecord->getName()
      << "(SDNode *N) {\n";
    else {
      std::string ClassName =
        CGP.getSDNodeInfo(P->getOnlyTree()->getOperator()).getSDClassName();
      const char *C2 = ClassName == "SDNode" ? "N" : "inN";
      
      OS << "inline bool Predicate_" << PatFragRecord->getName()
         << "(SDNode *" << C2 << ") {\n";
      if (ClassName != "SDNode")
        OS << "  " << ClassName << " *N = cast<" << ClassName << ">(inN);\n";
    }
    OS << Code << "\n}\n";
  }
  
  OS << "\n\n";
}


//===----------------------------------------------------------------------===//
// PatternCodeEmitter implementation.
//
class PatternCodeEmitter {
private:
  CodeGenDAGPatterns &CGP;

  // Predicates.
  std::string PredicateCheck;
  // Pattern cost.
  unsigned Cost;
  // Instruction selector pattern.
  TreePatternNode *Pattern;
  // Matched instruction.
  TreePatternNode *Instruction;
  
  // Node to name mapping
  std::map<std::string, std::string> VariableMap;
  // Node to operator mapping
  std::map<std::string, Record*> OperatorMap;
  // Name of the folded node which produces a flag.
  std::pair<std::string, unsigned> FoldedFlag;
  // Names of all the folded nodes which produce chains.
  std::vector<std::pair<std::string, unsigned> > FoldedChains;
  // Original input chain(s).
  std::vector<std::pair<std::string, std::string> > OrigChains;
  std::set<std::string> Duplicates;

  /// LSI - Load/Store information.
  /// Save loads/stores matched by a pattern, and generate a MemOperandSDNode
  /// for each memory access. This facilitates the use of AliasAnalysis in
  /// the backend.
  std::vector<std::string> LSI;

  /// GeneratedCode - This is the buffer that we emit code to.  The first int
  /// indicates whether this is an exit predicate (something that should be
  /// tested, and if true, the match fails) [when 1], or normal code to emit
  /// [when 0], or initialization code to emit [when 2].
  std::vector<std::pair<unsigned, std::string> > &GeneratedCode;
  /// GeneratedDecl - This is the set of all SDValue declarations needed for
  /// the set of patterns for each top-level opcode.
  std::set<std::string> &GeneratedDecl;
  /// TargetOpcodes - The target specific opcodes used by the resulting
  /// instructions.
  std::vector<std::string> &TargetOpcodes;
  std::vector<std::string> &TargetVTs;
  /// OutputIsVariadic - Records whether the instruction output pattern uses
  /// variable_ops.  This requires that the Emit function be passed an
  /// additional argument to indicate where the input varargs operands
  /// begin.
  bool &OutputIsVariadic;
  /// NumInputRootOps - Records the number of operands the root node of the
  /// input pattern has.  This information is used in the generated code to
  /// pass to Emit functions when variable_ops processing is needed.
  unsigned &NumInputRootOps;

  std::string ChainName;
  unsigned TmpNo;
  unsigned OpcNo;
  unsigned VTNo;
  
  void emitCheck(const std::string &S) {
    if (!S.empty())
      GeneratedCode.push_back(std::make_pair(1, S));
  }
  void emitCode(const std::string &S) {
    if (!S.empty())
      GeneratedCode.push_back(std::make_pair(0, S));
  }
  void emitInit(const std::string &S) {
    if (!S.empty())
      GeneratedCode.push_back(std::make_pair(2, S));
  }
  void emitDecl(const std::string &S) {
    assert(!S.empty() && "Invalid declaration");
    GeneratedDecl.insert(S);
  }
  void emitOpcode(const std::string &Opc) {
    TargetOpcodes.push_back(Opc);
    OpcNo++;
  }
  void emitVT(const std::string &VT) {
    TargetVTs.push_back(VT);
    VTNo++;
  }
public:
  PatternCodeEmitter(CodeGenDAGPatterns &cgp, std::string predcheck,
                     TreePatternNode *pattern, TreePatternNode *instr,
                     std::vector<std::pair<unsigned, std::string> > &gc,
                     std::set<std::string> &gd,
                     std::vector<std::string> &to,
                     std::vector<std::string> &tv,
                     bool &oiv,
                     unsigned &niro)
  : CGP(cgp), PredicateCheck(predcheck), Pattern(pattern), Instruction(instr),
    GeneratedCode(gc), GeneratedDecl(gd),
    TargetOpcodes(to), TargetVTs(tv),
    OutputIsVariadic(oiv), NumInputRootOps(niro),
    TmpNo(0), OpcNo(0), VTNo(0) {}

  /// EmitMatchCode - Emit a matcher for N, going to the label for PatternNo
  /// if the match fails. At this point, we already know that the opcode for N
  /// matches, and the SDNode for the result has the RootName specified name.
  void EmitMatchCode(TreePatternNode *N, TreePatternNode *P,
                     const std::string &RootName, const std::string &ChainSuffix,
                     bool &FoundChain);

  void EmitChildMatchCode(TreePatternNode *Child, TreePatternNode *Parent,
                          const std::string &RootName, 
                          const std::string &ChainSuffix, bool &FoundChain);

  /// EmitResultCode - Emit the action for a pattern.  Now that it has matched
  /// we actually have to build a DAG!
  std::vector<std::string>
  EmitResultCode(TreePatternNode *N, std::vector<Record*> DstRegs,
                 bool InFlagDecled, bool ResNodeDecled,
                 bool LikeLeaf = false, bool isRoot = false);

  /// InsertOneTypeCheck - Insert a type-check for an unresolved type in 'Pat'
  /// and add it to the tree. 'Pat' and 'Other' are isomorphic trees except that 
  /// 'Pat' may be missing types.  If we find an unresolved type to add a check
  /// for, this returns true otherwise false if Pat has all types.
  bool InsertOneTypeCheck(TreePatternNode *Pat, TreePatternNode *Other,
                          const std::string &Prefix, bool isRoot = false) {
    // Did we find one?
    if (Pat->getExtTypes() != Other->getExtTypes()) {
      // Move a type over from 'other' to 'pat'.
      Pat->setTypes(Other->getExtTypes());
      // The top level node type is checked outside of the select function.
      if (!isRoot)
        emitCheck(Prefix + ".getValueType() == " +
                  getName(Pat->getTypeNum(0)));
      return true;
    }
  
    unsigned OpNo =
      (unsigned) NodeHasProperty(Pat, SDNPHasChain, CGP);
    for (unsigned i = 0, e = Pat->getNumChildren(); i != e; ++i, ++OpNo)
      if (InsertOneTypeCheck(Pat->getChild(i), Other->getChild(i),
                             Prefix + utostr(OpNo)))
        return true;
    return false;
  }

private:
  /// EmitInFlagSelectCode - Emit the flag operands for the DAG that is
  /// being built.
  void EmitInFlagSelectCode(TreePatternNode *N, const std::string &RootName,
                            bool &ChainEmitted, bool &InFlagDecled,
                            bool &ResNodeDecled, bool isRoot = false) {
    const CodeGenTarget &T = CGP.getTargetInfo();
    unsigned OpNo =
      (unsigned) NodeHasProperty(N, SDNPHasChain, CGP);
    bool HasInFlag = NodeHasProperty(N, SDNPInFlag, CGP);
    for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i, ++OpNo) {
      TreePatternNode *Child = N->getChild(i);
      if (!Child->isLeaf()) {
        EmitInFlagSelectCode(Child, RootName + utostr(OpNo), ChainEmitted,
                             InFlagDecled, ResNodeDecled);
      } else {
        if (DefInit *DI = dynamic_cast<DefInit*>(Child->getLeafValue())) {
          if (!Child->getName().empty()) {
            std::string Name = RootName + utostr(OpNo);
            if (Duplicates.find(Name) != Duplicates.end())
              // A duplicate! Do not emit a copy for this node.
              continue;
          }

          Record *RR = DI->getDef();
          if (RR->isSubClassOf("Register")) {
            MVT::SimpleValueType RVT = getRegisterValueType(RR, T);
            if (RVT == MVT::Flag) {
              if (!InFlagDecled) {
                emitCode("SDValue InFlag = " +
                         getValueName(RootName + utostr(OpNo)) + ";");
                InFlagDecled = true;
              } else
                emitCode("InFlag = " +
                         getValueName(RootName + utostr(OpNo)) + ";");
            } else {
              if (!ChainEmitted) {
                emitCode("SDValue Chain = CurDAG->getEntryNode();");
                ChainName = "Chain";
                ChainEmitted = true;
              }
              if (!InFlagDecled) {
                emitCode("SDValue InFlag(0, 0);");
                InFlagDecled = true;
              }
              std::string Decl = (!ResNodeDecled) ? "SDNode *" : "";
              emitCode(Decl + "ResNode = CurDAG->getCopyToReg(" + ChainName +
                       ", " + getNodeName(RootName) + "->getDebugLoc()" +
                       ", " + getQualifiedName(RR) +
                       ", " +  getValueName(RootName + utostr(OpNo)) +
                       ", InFlag).getNode();");
              ResNodeDecled = true;
              emitCode(ChainName + " = SDValue(ResNode, 0);");
              emitCode("InFlag = SDValue(ResNode, 1);");
            }
          }
        }
      }
    }

    if (HasInFlag) {
      if (!InFlagDecled) {
        emitCode("SDValue InFlag = " + getNodeName(RootName) +
               "->getOperand(" + utostr(OpNo) + ");");
        InFlagDecled = true;
      } else
        emitCode("InFlag = " + getNodeName(RootName) +
               "->getOperand(" + utostr(OpNo) + ");");
    }
  }
};


/// EmitMatchCode - Emit a matcher for N, going to the label for PatternNo
/// if the match fails. At this point, we already know that the opcode for N
/// matches, and the SDNode for the result has the RootName specified name.
void PatternCodeEmitter::EmitMatchCode(TreePatternNode *N, TreePatternNode *P,
                                       const std::string &RootName,
                                       const std::string &ChainSuffix,
                                       bool &FoundChain) {
  
  // Save loads/stores matched by a pattern.
  if (!N->isLeaf() && N->getName().empty()) {
    if (NodeHasProperty(N, SDNPMemOperand, CGP))
      LSI.push_back(getNodeName(RootName));
  }
  
  bool isRoot = (P == NULL);
  // Emit instruction predicates. Each predicate is just a string for now.
  if (isRoot) {
    // Record input varargs info.
    NumInputRootOps = N->getNumChildren();
    emitCheck(PredicateCheck);
  }
  
  if (N->isLeaf()) {
    if (IntInit *II = dynamic_cast<IntInit*>(N->getLeafValue())) {
      emitCheck("cast<ConstantSDNode>(" + getNodeName(RootName) +
                ")->getSExtValue() == INT64_C(" +
                itostr(II->getValue()) + ")");
      return;
    } else if (!NodeIsComplexPattern(N)) {
      assert(0 && "Cannot match this as a leaf value!");
      abort();
    }
  }
  
  // If this node has a name associated with it, capture it in VariableMap. If
  // we already saw this in the pattern, emit code to verify dagness.
  if (!N->getName().empty()) {
    std::string &VarMapEntry = VariableMap[N->getName()];
    if (VarMapEntry.empty()) {
      VarMapEntry = RootName;
    } else {
      // If we get here, this is a second reference to a specific name.  Since
      // we already have checked that the first reference is valid, we don't
      // have to recursively match it, just check that it's the same as the
      // previously named thing.
      emitCheck(VarMapEntry + " == " + RootName);
      return;
    }
    
    if (!N->isLeaf())
      OperatorMap[N->getName()] = N->getOperator();
  }
  
  
  // Emit code to load the child nodes and match their contents recursively.
  unsigned OpNo = 0;
  bool NodeHasChain = NodeHasProperty   (N, SDNPHasChain, CGP);
  bool HasChain     = PatternHasProperty(N, SDNPHasChain, CGP);
  bool EmittedUseCheck = false;
  if (HasChain) {
    if (NodeHasChain)
      OpNo = 1;
    if (!isRoot) {
      // Multiple uses of actual result?
      emitCheck(getValueName(RootName) + ".hasOneUse()");
      EmittedUseCheck = true;
      if (NodeHasChain) {
        // If the immediate use can somehow reach this node through another
        // path, then can't fold it either or it will create a cycle.
        // e.g. In the following diagram, XX can reach ld through YY. If
        // ld is folded into XX, then YY is both a predecessor and a successor
        // of XX.
        //
        //         [ld]
        //         ^  ^
        //         |  |
        //        /   \---
        //      /        [YY]
        //      |         ^
        //     [XX]-------|
        bool NeedCheck = P != Pattern;
        if (!NeedCheck) {
          const SDNodeInfo &PInfo = CGP.getSDNodeInfo(P->getOperator());
          NeedCheck =
          P->getOperator() == CGP.get_intrinsic_void_sdnode() ||
          P->getOperator() == CGP.get_intrinsic_w_chain_sdnode() ||
          P->getOperator() == CGP.get_intrinsic_wo_chain_sdnode() ||
          PInfo.getNumOperands() > 1 ||
          PInfo.hasProperty(SDNPHasChain) ||
          PInfo.hasProperty(SDNPInFlag) ||
          PInfo.hasProperty(SDNPOptInFlag);
        }
        
        if (NeedCheck) {
          std::string ParentName(RootName.begin(), RootName.end()-1);
          emitCheck("IsLegalAndProfitableToFold(" + getNodeName(RootName) +
                    ", " + getNodeName(ParentName) + ", N)");
        }
      }
    }
    
    if (NodeHasChain) {
      if (FoundChain) {
        emitCheck("(" + ChainName + ".getNode() == " +
                  getNodeName(RootName) + " || "
                  "IsChainCompatible(" + ChainName + ".getNode(), " +
                  getNodeName(RootName) + "))");
        OrigChains.push_back(std::make_pair(ChainName,
                                            getValueName(RootName)));
      } else
        FoundChain = true;
      ChainName = "Chain" + ChainSuffix;
      emitInit("SDValue " + ChainName + " = " + getNodeName(RootName) +
               "->getOperand(0);");
    }
  }
  
  // Don't fold any node which reads or writes a flag and has multiple uses.
  // FIXME: We really need to separate the concepts of flag and "glue". Those
  // real flag results, e.g. X86CMP output, can have multiple uses.
  // FIXME: If the optional incoming flag does not exist. Then it is ok to
  // fold it.
  if (!isRoot &&
      (PatternHasProperty(N, SDNPInFlag, CGP) ||
       PatternHasProperty(N, SDNPOptInFlag, CGP) ||
       PatternHasProperty(N, SDNPOutFlag, CGP))) {
        if (!EmittedUseCheck) {
          // Multiple uses of actual result?
          emitCheck(getValueName(RootName) + ".hasOneUse()");
        }
      }
  
  // If there are node predicates for this, emit the calls.
  for (unsigned i = 0, e = N->getPredicateFns().size(); i != e; ++i)
    emitCheck(N->getPredicateFns()[i] + "(" + getNodeName(RootName) + ")");
  
  // If this is an 'and R, 1234' where the operation is AND/OR and the RHS is
  // a constant without a predicate fn that has more that one bit set, handle
  // this as a special case.  This is usually for targets that have special
  // handling of certain large constants (e.g. alpha with it's 8/16/32-bit
  // handling stuff).  Using these instructions is often far more efficient
  // than materializing the constant.  Unfortunately, both the instcombiner
  // and the dag combiner can often infer that bits are dead, and thus drop
  // them from the mask in the dag.  For example, it might turn 'AND X, 255'
  // into 'AND X, 254' if it knows the low bit is set.  Emit code that checks
  // to handle this.
  if (!N->isLeaf() && 
      (N->getOperator()->getName() == "and" || 
       N->getOperator()->getName() == "or") &&
      N->getChild(1)->isLeaf() &&
      N->getChild(1)->getPredicateFns().empty()) {
    if (IntInit *II = dynamic_cast<IntInit*>(N->getChild(1)->getLeafValue())) {
      if (!isPowerOf2_32(II->getValue())) {  // Don't bother with single bits.
        emitInit("SDValue " + RootName + "0" + " = " +
                 getNodeName(RootName) + "->getOperand(" + utostr(0) + ");");
        emitInit("SDValue " + RootName + "1" + " = " +
                 getNodeName(RootName) + "->getOperand(" + utostr(1) + ");");
        
        unsigned NTmp = TmpNo++;
        emitCode("ConstantSDNode *Tmp" + utostr(NTmp) +
                 " = dyn_cast<ConstantSDNode>(" +
                 getNodeName(RootName + "1") + ");");
        emitCheck("Tmp" + utostr(NTmp));
        const char *MaskPredicate = N->getOperator()->getName() == "or"
        ? "CheckOrMask(" : "CheckAndMask(";
        emitCheck(MaskPredicate + getValueName(RootName + "0") +
                  ", Tmp" + utostr(NTmp) +
                  ", INT64_C(" + itostr(II->getValue()) + "))");
        
        EmitChildMatchCode(N->getChild(0), N, RootName + utostr(0),
                           ChainSuffix + utostr(0), FoundChain);
        return;
      }
    }
  }
  
  for (unsigned i = 0, e = N->getNumChildren(); i != e; ++i, ++OpNo) {
    emitInit("SDValue " + getValueName(RootName + utostr(OpNo)) + " = " +
             getNodeName(RootName) + "->getOperand(" + utostr(OpNo) + ");");
    
    EmitChildMatchCode(N->getChild(i), N, RootName + utostr(OpNo),
                       ChainSuffix + utostr(OpNo), FoundChain);
  }
  
  // Handle cases when root is a complex pattern.
  const ComplexPattern *CP;
  if (isRoot && N->isLeaf() && (CP = NodeGetComplexPattern(N, CGP))) {
    std::string Fn = CP->getSelectFunc();
    unsigned NumOps = CP->getNumOperands();
    for (unsigned i = 0; i < NumOps; ++i) {
      emitDecl("CPTmp" + RootName + "_" + utostr(i));
      emitCode("SDValue CPTmp" + RootName + "_" + utostr(i) + ";");
    }
    if (CP->hasProperty(SDNPHasChain)) {
      emitDecl("CPInChain");
      emitDecl("Chain" + ChainSuffix);
      emitCode("SDValue CPInChain;");
      emitCode("SDValue Chain" + ChainSuffix + ";");
    }
    
    std::string Code = Fn + "(" +
    getNodeName(RootName) + ", " +
    getValueName(RootName);
    for (unsigned i = 0; i < NumOps; i++)
      Code += ", CPTmp" + RootName + "_" + utostr(i);
    if (CP->hasProperty(SDNPHasChain)) {
      ChainName = "Chain" + ChainSuffix;
      Code += ", CPInChain, Chain" + ChainSuffix;
    }
    emitCheck(Code + ")");
  }
}

void PatternCodeEmitter::EmitChildMatchCode(TreePatternNode *Child,
                                            TreePatternNode *Parent,
                                            const std::string &RootName, 
                                            const std::string &ChainSuffix,
                                            bool &FoundChain) {
  if (!Child->isLeaf()) {
    // If it's not a leaf, recursively match.
    const SDNodeInfo &CInfo = CGP.getSDNodeInfo(Child->getOperator());
    emitCheck(getNodeName(RootName) + "->getOpcode() == " +
              CInfo.getEnumName());
    EmitMatchCode(Child, Parent, RootName, ChainSuffix, FoundChain);
    bool HasChain = false;
    if (NodeHasProperty(Child, SDNPHasChain, CGP)) {
      HasChain = true;
      FoldedChains.push_back(std::make_pair(getValueName(RootName),
                                            CInfo.getNumResults()));
    }
    if (NodeHasProperty(Child, SDNPOutFlag, CGP)) {
      assert(FoldedFlag.first == "" && FoldedFlag.second == 0 &&
             "Pattern folded multiple nodes which produce flags?");
      FoldedFlag = std::make_pair(getValueName(RootName),
                                  CInfo.getNumResults() + (unsigned)HasChain);
    }
  } else {
    // If this child has a name associated with it, capture it in VarMap. If
    // we already saw this in the pattern, emit code to verify dagness.
    if (!Child->getName().empty()) {
      std::string &VarMapEntry = VariableMap[Child->getName()];
      if (VarMapEntry.empty()) {
        VarMapEntry = getValueName(RootName);
      } else {
        // If we get here, this is a second reference to a specific name.
        // Since we already have checked that the first reference is valid,
        // we don't have to recursively match it, just check that it's the
        // same as the previously named thing.
        emitCheck(VarMapEntry + " == " + getValueName(RootName));
        Duplicates.insert(getValueName(RootName));
        return;
      }
    }
    
    // Handle leaves of various types.
    if (DefInit *DI = dynamic_cast<DefInit*>(Child->getLeafValue())) {
      Record *LeafRec = DI->getDef();
      if (LeafRec->isSubClassOf("RegisterClass") || 
          LeafRec->isSubClassOf("PointerLikeRegClass")) {
        // Handle register references.  Nothing to do here.
      } else if (LeafRec->isSubClassOf("Register")) {
        // Handle register references.
      } else if (LeafRec->isSubClassOf("ComplexPattern")) {
        // Handle complex pattern.
        const ComplexPattern *CP = NodeGetComplexPattern(Child, CGP);
        std::string Fn = CP->getSelectFunc();
        unsigned NumOps = CP->getNumOperands();
        for (unsigned i = 0; i < NumOps; ++i) {
          emitDecl("CPTmp" + RootName + "_" + utostr(i));
          emitCode("SDValue CPTmp" + RootName + "_" + utostr(i) + ";");
        }
        if (CP->hasProperty(SDNPHasChain)) {
          const SDNodeInfo &PInfo = CGP.getSDNodeInfo(Parent->getOperator());
          FoldedChains.push_back(std::make_pair("CPInChain",
                                                PInfo.getNumResults()));
          ChainName = "Chain" + ChainSuffix;
          emitDecl("CPInChain");
          emitDecl(ChainName);
          emitCode("SDValue CPInChain;");
          emitCode("SDValue " + ChainName + ";");
        }
        
        std::string Code = Fn + "(N, ";
        if (CP->hasProperty(SDNPHasChain)) {
          std::string ParentName(RootName.begin(), RootName.end()-1);
          Code += getValueName(ParentName) + ", ";
        }
        Code += getValueName(RootName);
        for (unsigned i = 0; i < NumOps; i++)
          Code += ", CPTmp" + RootName + "_" + utostr(i);
        if (CP->hasProperty(SDNPHasChain))
          Code += ", CPInChain, Chain" + ChainSuffix;
        emitCheck(Code + ")");
      } else if (LeafRec->getName() == "srcvalue") {
        // Place holder for SRCVALUE nodes. Nothing to do here.
      } else if (LeafRec->isSubClassOf("ValueType")) {
        // Make sure this is the specified value type.
        emitCheck("cast<VTSDNode>(" + getNodeName(RootName) +
                  ")->getVT() == MVT::" + LeafRec->getName());
      } else if (LeafRec->isSubClassOf("CondCode")) {
        // Make sure this is the specified cond code.
        emitCheck("cast<CondCodeSDNode>(" + getNodeName(RootName) +
                  ")->get() == ISD::" + LeafRec->getName());
      } else {
#ifndef NDEBUG
        Child->dump();
        errs() << " ";
#endif
        assert(0 && "Unknown leaf type!");
      }
      
      // If there are node predicates for this, emit the calls.
      for (unsigned i = 0, e = Child->getPredicateFns().size(); i != e; ++i)
        emitCheck(Child->getPredicateFns()[i] + "(" + getNodeName(RootName) +
                  ")");
    } else if (IntInit *II =
               dynamic_cast<IntInit*>(Child->getLeafValue())) {
      unsigned NTmp = TmpNo++;
      emitCode("ConstantSDNode *Tmp"+ utostr(NTmp) +
               " = dyn_cast<ConstantSDNode>("+
               getNodeName(RootName) + ");");
      emitCheck("Tmp" + utostr(NTmp));
      unsigned CTmp = TmpNo++;
      emitCode("int64_t CN"+ utostr(CTmp) +
               " = Tmp" + utostr(NTmp) + "->getSExtValue();");
      emitCheck("CN" + utostr(CTmp) + " == "
                "INT64_C(" +itostr(II->getValue()) + ")");
    } else {
#ifndef NDEBUG
      Child->dump();
#endif
      assert(0 && "Unknown leaf type!");
    }
  }
}

/// EmitResultCode - Emit the action for a pattern.  Now that it has matched
/// we actually have to build a DAG!
std::vector<std::string>
PatternCodeEmitter::EmitResultCode(TreePatternNode *N, 
                                   std::vector<Record*> DstRegs,
                                   bool InFlagDecled, bool ResNodeDecled,
                                   bool LikeLeaf, bool isRoot) {
  // List of arguments of getMachineNode() or SelectNodeTo().
  std::vector<std::string> NodeOps;
  // This is something selected from the pattern we matched.
  if (!N->getName().empty()) {
    const std::string &VarName = N->getName();
    std::string Val = VariableMap[VarName];
    bool ModifiedVal = false;
    if (Val.empty()) {
      errs() << "Variable '" << VarName << " referenced but not defined "
      << "and not caught earlier!\n";
      abort();
    }
    if (Val[0] == 'T' && Val[1] == 'm' && Val[2] == 'p') {
      // Already selected this operand, just return the tmpval.
      NodeOps.push_back(getValueName(Val));
      return NodeOps;
    }
    
    const ComplexPattern *CP;
    unsigned ResNo = TmpNo++;
    if (!N->isLeaf() && N->getOperator()->getName() == "imm") {
      assert(N->getExtTypes().size() == 1 && "Multiple types not handled!");
      std::string CastType;
      std::string TmpVar =  "Tmp" + utostr(ResNo);
      switch (N->getTypeNum(0)) {
        default:
          errs() << "Cannot handle " << getEnumName(N->getTypeNum(0))
          << " type as an immediate constant. Aborting\n";
          abort();
        case MVT::i1:  CastType = "bool"; break;
        case MVT::i8:  CastType = "unsigned char"; break;
        case MVT::i16: CastType = "unsigned short"; break;
        case MVT::i32: CastType = "unsigned"; break;
        case MVT::i64: CastType = "uint64_t"; break;
      }
      emitCode("SDValue " + TmpVar + 
               " = CurDAG->getTargetConstant(((" + CastType +
               ") cast<ConstantSDNode>(" + Val + ")->getZExtValue()), " +
               getEnumName(N->getTypeNum(0)) + ");");
      // Add Tmp<ResNo> to VariableMap, so that we don't multiply select this
      // value if used multiple times by this pattern result.
      Val = TmpVar;
      ModifiedVal = true;
      NodeOps.push_back(getValueName(Val));
    } else if (!N->isLeaf() && N->getOperator()->getName() == "fpimm") {
      assert(N->getExtTypes().size() == 1 && "Multiple types not handled!");
      std::string TmpVar =  "Tmp" + utostr(ResNo);
      emitCode("SDValue " + TmpVar + 
               " = CurDAG->getTargetConstantFP(*cast<ConstantFPSDNode>(" + 
               Val + ")->getConstantFPValue(), cast<ConstantFPSDNode>(" +
               Val + ")->getValueType(0));");
      // Add Tmp<ResNo> to VariableMap, so that we don't multiply select this
      // value if used multiple times by this pattern result.
      Val = TmpVar;
      ModifiedVal = true;
      NodeOps.push_back(getValueName(Val));
    } else if (!N->isLeaf() && N->getOperator()->getName() == "texternalsym"){
      Record *Op = OperatorMap[N->getName()];
      // Transform ExternalSymbol to TargetExternalSymbol
      if (Op && Op->getName() == "externalsym") {
        std::string TmpVar = "Tmp"+utostr(ResNo);
        emitCode("SDValue " + TmpVar + " = CurDAG->getTarget"
                 "ExternalSymbol(cast<ExternalSymbolSDNode>(" +
                 Val + ")->getSymbol(), " +
                 getEnumName(N->getTypeNum(0)) + ");");
        // Add Tmp<ResNo> to VariableMap, so that we don't multiply select
        // this value if used multiple times by this pattern result.
        Val = TmpVar;
        ModifiedVal = true;
      }
      NodeOps.push_back(getValueName(Val));
    } else if (!N->isLeaf() && (N->getOperator()->getName() == "tglobaladdr"
                                || N->getOperator()->getName() == "tglobaltlsaddr")) {
      Record *Op = OperatorMap[N->getName()];
      // Transform GlobalAddress to TargetGlobalAddress
      if (Op && (Op->getName() == "globaladdr" ||
                 Op->getName() == "globaltlsaddr")) {
        std::string TmpVar = "Tmp" + utostr(ResNo);
        emitCode("SDValue " + TmpVar + " = CurDAG->getTarget"
                 "GlobalAddress(cast<GlobalAddressSDNode>(" + Val +
                 ")->getGlobal(), " + getEnumName(N->getTypeNum(0)) +
                 ");");
        // Add Tmp<ResNo> to VariableMap, so that we don't multiply select
        // this value if used multiple times by this pattern result.
        Val = TmpVar;
        ModifiedVal = true;
      }
      NodeOps.push_back(getValueName(Val));
    } else if (!N->isLeaf()
               && (N->getOperator()->getName() == "texternalsym"
                   || N->getOperator()->getName() == "tconstpool")) {
                 // Do not rewrite the variable name, since we don't generate a new
                 // temporary.
                 NodeOps.push_back(getValueName(Val));
               } else if (N->isLeaf() && (CP = NodeGetComplexPattern(N, CGP))) {
                 for (unsigned i = 0; i < CP->getNumOperands(); ++i) {
                   NodeOps.push_back(getValueName("CPTmp" + Val + "_" + utostr(i)));
                 }
               } else {
                 // This node, probably wrapped in a SDNodeXForm, behaves like a leaf
                 // node even if it isn't one. Don't select it.
                 if (!LikeLeaf) {
                   if (isRoot && N->isLeaf()) {
                     emitCode("ReplaceUses(SDValue(N, 0), " + Val + ");");
                     emitCode("return NULL;");
                   }
                 }
                 NodeOps.push_back(getValueName(Val));
               }
    
    if (ModifiedVal) {
      VariableMap[VarName] = Val;
    }
    return NodeOps;
  }
  if (N->isLeaf()) {
    // If this is an explicit register reference, handle it.
    if (DefInit *DI = dynamic_cast<DefInit*>(N->getLeafValue())) {
      unsigned ResNo = TmpNo++;
      if (DI->getDef()->isSubClassOf("Register")) {
        emitCode("SDValue Tmp" + utostr(ResNo) + " = CurDAG->getRegister(" +
                 getQualifiedName(DI->getDef()) + ", " +
                 getEnumName(N->getTypeNum(0)) + ");");
        NodeOps.push_back(getValueName("Tmp" + utostr(ResNo)));
        return NodeOps;
      } else if (DI->getDef()->getName() == "zero_reg") {
        emitCode("SDValue Tmp" + utostr(ResNo) +
                 " = CurDAG->getRegister(0, " +
                 getEnumName(N->getTypeNum(0)) + ");");
        NodeOps.push_back(getValueName("Tmp" + utostr(ResNo)));
        return NodeOps;
      } else if (DI->getDef()->isSubClassOf("RegisterClass")) {
        // Handle a reference to a register class. This is used
        // in COPY_TO_SUBREG instructions.
        emitCode("SDValue Tmp" + utostr(ResNo) +
                 " = CurDAG->getTargetConstant(" +
                 getQualifiedName(DI->getDef()) + "RegClassID, " +
                 "MVT::i32);");
        NodeOps.push_back(getValueName("Tmp" + utostr(ResNo)));
        return NodeOps;
      }
    } else if (IntInit *II = dynamic_cast<IntInit*>(N->getLeafValue())) {
      unsigned ResNo = TmpNo++;
      assert(N->getExtTypes().size() == 1 && "Multiple types not handled!");
      emitCode("SDValue Tmp" + utostr(ResNo) + 
               " = CurDAG->getTargetConstant(0x" + 
               utohexstr((uint64_t) II->getValue()) +
               "ULL, " + getEnumName(N->getTypeNum(0)) + ");");
      NodeOps.push_back(getValueName("Tmp" + utostr(ResNo)));
      return NodeOps;
    }
    
#ifndef NDEBUG
    N->dump();
#endif
    assert(0 && "Unknown leaf type!");
    return NodeOps;
  }
  
  Record *Op = N->getOperator();
  if (Op->isSubClassOf("Instruction")) {
    const CodeGenTarget &CGT = CGP.getTargetInfo();
    CodeGenInstruction &II = CGT.getInstruction(Op->getName());
    const DAGInstruction &Inst = CGP.getInstruction(Op);
    const TreePattern *InstPat = Inst.getPattern();
    // FIXME: Assume actual pattern comes before "implicit".
    TreePatternNode *InstPatNode =
    isRoot ? (InstPat ? InstPat->getTree(0) : Pattern)
    : (InstPat ? InstPat->getTree(0) : NULL);
    if (InstPatNode && !InstPatNode->isLeaf() &&
        InstPatNode->getOperator()->getName() == "set") {
      InstPatNode = InstPatNode->getChild(InstPatNode->getNumChildren()-1);
    }
    bool IsVariadic = isRoot && II.isVariadic;
    // FIXME: fix how we deal with physical register operands.
    bool HasImpInputs  = isRoot && Inst.getNumImpOperands() > 0;
    bool HasImpResults = isRoot && DstRegs.size() > 0;
    bool NodeHasOptInFlag = isRoot &&
    PatternHasProperty(Pattern, SDNPOptInFlag, CGP);
    bool NodeHasInFlag  = isRoot &&
    PatternHasProperty(Pattern, SDNPInFlag, CGP);
    bool NodeHasOutFlag = isRoot &&
    PatternHasProperty(Pattern, SDNPOutFlag, CGP);
    bool NodeHasChain = InstPatNode &&
    PatternHasProperty(InstPatNode, SDNPHasChain, CGP);
    bool InputHasChain = isRoot &&
    NodeHasProperty(Pattern, SDNPHasChain, CGP);
    unsigned NumResults = Inst.getNumResults();    
    unsigned NumDstRegs = HasImpResults ? DstRegs.size() : 0;
    
    // Record output varargs info.
    OutputIsVariadic = IsVariadic;
    
    if (NodeHasOptInFlag) {
      emitCode("bool HasInFlag = "
               "(N->getOperand(N->getNumOperands()-1).getValueType() == "
               "MVT::Flag);");
    }
    if (IsVariadic)
      emitCode("SmallVector<SDValue, 8> Ops" + utostr(OpcNo) + ";");
    
    // How many results is this pattern expected to produce?
    unsigned NumPatResults = 0;
    for (unsigned i = 0, e = Pattern->getExtTypes().size(); i != e; i++) {
      MVT::SimpleValueType VT = Pattern->getTypeNum(i);
      if (VT != MVT::isVoid && VT != MVT::Flag)
        NumPatResults++;
    }
    
    if (OrigChains.size() > 0) {
      // The original input chain is being ignored. If it is not just
      // pointing to the op that's being folded, we should create a
      // TokenFactor with it and the chain of the folded op as the new chain.
      // We could potentially be doing multiple levels of folding, in that
      // case, the TokenFactor can have more operands.
      emitCode("SmallVector<SDValue, 8> InChains;");
      for (unsigned i = 0, e = OrigChains.size(); i < e; ++i) {
        emitCode("if (" + OrigChains[i].first + ".getNode() != " +
                 OrigChains[i].second + ".getNode()) {");
        emitCode("  InChains.push_back(" + OrigChains[i].first + ");");
        emitCode("}");
      }
      emitCode("InChains.push_back(" + ChainName + ");");
      emitCode(ChainName + " = CurDAG->getNode(ISD::TokenFactor, "
               "N->getDebugLoc(), MVT::Other, "
               "&InChains[0], InChains.size());");
      if (GenDebug) {
        emitCode("CurDAG->setSubgraphColor(" + ChainName +".getNode(), \"yellow\");");
        emitCode("CurDAG->setSubgraphColor(" + ChainName +".getNode(), \"black\");");
      }
    }
    
    // Loop over all of the operands of the instruction pattern, emitting code
    // to fill them all in.  The node 'N' usually has number children equal to
    // the number of input operands of the instruction.  However, in cases
    // where there are predicate operands for an instruction, we need to fill
    // in the 'execute always' values.  Match up the node operands to the
    // instruction operands to do this.
    std::vector<std::string> AllOps;
    for (unsigned ChildNo = 0, InstOpNo = NumResults;
         InstOpNo != II.OperandList.size(); ++InstOpNo) {
      std::vector<std::string> Ops;
      
      // Determine what to emit for this operand.
      Record *OperandNode = II.OperandList[InstOpNo].Rec;
      if ((OperandNode->isSubClassOf("PredicateOperand") ||
           OperandNode->isSubClassOf("OptionalDefOperand")) &&
          !CGP.getDefaultOperand(OperandNode).DefaultOps.empty()) {
        // This is a predicate or optional def operand; emit the
        // 'default ops' operands.
        const DAGDefaultOperand &DefaultOp =
        CGP.getDefaultOperand(II.OperandList[InstOpNo].Rec);
        for (unsigned i = 0, e = DefaultOp.DefaultOps.size(); i != e; ++i) {
          Ops = EmitResultCode(DefaultOp.DefaultOps[i], DstRegs,
                               InFlagDecled, ResNodeDecled);
          AllOps.insert(AllOps.end(), Ops.begin(), Ops.end());
        }
      } else {
        // Otherwise this is a normal operand or a predicate operand without
        // 'execute always'; emit it.
        Ops = EmitResultCode(N->getChild(ChildNo), DstRegs,
                             InFlagDecled, ResNodeDecled);
        AllOps.insert(AllOps.end(), Ops.begin(), Ops.end());
        ++ChildNo;
      }
    }
    
    // Emit all the chain and CopyToReg stuff.
    bool ChainEmitted = NodeHasChain;
    if (NodeHasInFlag || HasImpInputs)
      EmitInFlagSelectCode(Pattern, "N", ChainEmitted,
                           InFlagDecled, ResNodeDecled, true);
    if (NodeHasOptInFlag || NodeHasInFlag || HasImpInputs) {
      if (!InFlagDecled) {
        emitCode("SDValue InFlag(0, 0);");
        InFlagDecled = true;
      }
      if (NodeHasOptInFlag) {
        emitCode("if (HasInFlag) {");
        emitCode("  InFlag = N->getOperand(N->getNumOperands()-1);");
        emitCode("}");
      }
    }
    
    unsigned ResNo = TmpNo++;
    
    unsigned OpsNo = OpcNo;
    std::string CodePrefix;
    bool ChainAssignmentNeeded = NodeHasChain && !isRoot;
    std::deque<std::string> After;
    std::string NodeName;
    if (!isRoot) {
      NodeName = "Tmp" + utostr(ResNo);
      CodePrefix = "SDValue " + NodeName + "(";
    } else {
      NodeName = "ResNode";
      if (!ResNodeDecled) {
        CodePrefix = "SDNode *" + NodeName + " = ";
        ResNodeDecled = true;
      } else
        CodePrefix = NodeName + " = ";
    }
    
    std::string Code = "Opc" + utostr(OpcNo);
    
    if (!isRoot || (InputHasChain && !NodeHasChain))
      // For call to "getMachineNode()".
      Code += ", N->getDebugLoc()";
    
    emitOpcode(II.Namespace + "::" + II.TheDef->getName());
    
    // Output order: results, chain, flags
    // Result types.
    if (NumResults > 0 && N->getTypeNum(0) != MVT::isVoid) {
      Code += ", VT" + utostr(VTNo);
      emitVT(getEnumName(N->getTypeNum(0)));
    }
    // Add types for implicit results in physical registers, scheduler will
    // care of adding copyfromreg nodes.
    for (unsigned i = 0; i < NumDstRegs; i++) {
      Record *RR = DstRegs[i];
      if (RR->isSubClassOf("Register")) {
        MVT::SimpleValueType RVT = getRegisterValueType(RR, CGT);
        Code += ", " + getEnumName(RVT);
      }
    }
    if (NodeHasChain)
      Code += ", MVT::Other";
    if (NodeHasOutFlag)
      Code += ", MVT::Flag";
    
    // Inputs.
    if (IsVariadic) {
      for (unsigned i = 0, e = AllOps.size(); i != e; ++i)
        emitCode("Ops" + utostr(OpsNo) + ".push_back(" + AllOps[i] + ");");
      AllOps.clear();
      
      // Figure out whether any operands at the end of the op list are not
      // part of the variable section.
      std::string EndAdjust;
      if (NodeHasInFlag || HasImpInputs)
        EndAdjust = "-1";  // Always has one flag.
      else if (NodeHasOptInFlag)
        EndAdjust = "-(HasInFlag?1:0)"; // May have a flag.
      
      emitCode("for (unsigned i = NumInputRootOps + " + utostr(NodeHasChain) +
               ", e = N->getNumOperands()" + EndAdjust + "; i != e; ++i) {");
      
      emitCode("  Ops" + utostr(OpsNo) + ".push_back(N->getOperand(i));");
      emitCode("}");
    }
    
    // Populate MemRefs with entries for each memory accesses covered by 
    // this pattern.
    if (isRoot && !LSI.empty()) {
      std::string MemRefs = "MemRefs" + utostr(OpsNo);
      emitCode("MachineSDNode::mmo_iterator " + MemRefs + " = "
               "MF->allocateMemRefsArray(" + utostr(LSI.size()) + ");");
      for (unsigned i = 0, e = LSI.size(); i != e; ++i)
        emitCode(MemRefs + "[" + utostr(i) + "] = "
                 "cast<MemSDNode>(" + LSI[i] + ")->getMemOperand();");
      After.push_back("cast<MachineSDNode>(ResNode)->setMemRefs(" +
                      MemRefs + ", " + MemRefs + " + " + utostr(LSI.size()) +
                      ");");
    }
    
    if (NodeHasChain) {
      if (IsVariadic)
        emitCode("Ops" + utostr(OpsNo) + ".push_back(" + ChainName + ");");
      else
        AllOps.push_back(ChainName);
    }
    
    if (IsVariadic) {
      if (NodeHasInFlag || HasImpInputs)
        emitCode("Ops" + utostr(OpsNo) + ".push_back(InFlag);");
      else if (NodeHasOptInFlag) {
        emitCode("if (HasInFlag)");
        emitCode("  Ops" + utostr(OpsNo) + ".push_back(InFlag);");
      }
      Code += ", &Ops" + utostr(OpsNo) + "[0], Ops" + utostr(OpsNo) +
      ".size()";
    } else if (NodeHasInFlag || NodeHasOptInFlag || HasImpInputs)
      AllOps.push_back("InFlag");
    
    unsigned NumOps = AllOps.size();
    if (NumOps) {
      if (!NodeHasOptInFlag && NumOps < 4) {
        for (unsigned i = 0; i != NumOps; ++i)
          Code += ", " + AllOps[i];
      } else {
        std::string OpsCode = "SDValue Ops" + utostr(OpsNo) + "[] = { ";
        for (unsigned i = 0; i != NumOps; ++i) {
          OpsCode += AllOps[i];
          if (i != NumOps-1)
            OpsCode += ", ";
        }
        emitCode(OpsCode + " };");
        Code += ", Ops" + utostr(OpsNo) + ", ";
        if (NodeHasOptInFlag) {
          Code += "HasInFlag ? ";
          Code += utostr(NumOps) + " : " + utostr(NumOps-1);
        } else
          Code += utostr(NumOps);
      }
    }
    
    if (!isRoot)
      Code += "), 0";
    
    std::vector<std::string> ReplaceFroms;
    std::vector<std::string> ReplaceTos;
    if (!isRoot) {
      NodeOps.push_back("Tmp" + utostr(ResNo));
    } else {
      
      if (NodeHasOutFlag) {
        if (!InFlagDecled) {
          After.push_back("SDValue InFlag(ResNode, " + 
                          utostr(NumResults+NumDstRegs+(unsigned)NodeHasChain) +
                          ");");
          InFlagDecled = true;
        } else
          After.push_back("InFlag = SDValue(ResNode, " + 
                          utostr(NumResults+NumDstRegs+(unsigned)NodeHasChain) +
                          ");");
      }
      
      for (unsigned j = 0, e = FoldedChains.size(); j < e; j++) {
        ReplaceFroms.push_back("SDValue(" +
                               FoldedChains[j].first + ".getNode(), " +
                               utostr(FoldedChains[j].second) +
                               ")");
        ReplaceTos.push_back("SDValue(ResNode, " +
                             utostr(NumResults+NumDstRegs) + ")");
      }
      
      if (NodeHasOutFlag) {
        if (FoldedFlag.first != "") {
          ReplaceFroms.push_back("SDValue(" + FoldedFlag.first + ".getNode(), " +
                                 utostr(FoldedFlag.second) + ")");
          ReplaceTos.push_back("InFlag");
        } else {
          assert(NodeHasProperty(Pattern, SDNPOutFlag, CGP));
          ReplaceFroms.push_back("SDValue(N, " +
                                 utostr(NumPatResults + (unsigned)InputHasChain)
                                 + ")");
          ReplaceTos.push_back("InFlag");
        }
      }
      
      if (!ReplaceFroms.empty() && InputHasChain) {
        ReplaceFroms.push_back("SDValue(N, " +
                               utostr(NumPatResults) + ")");
        ReplaceTos.push_back("SDValue(" + ChainName + ".getNode(), " +
                             ChainName + ".getResNo()" + ")");
        ChainAssignmentNeeded |= NodeHasChain;
      }
      
      // User does not expect the instruction would produce a chain!
      if ((!InputHasChain && NodeHasChain) && NodeHasOutFlag) {
        ;
      } else if (InputHasChain && !NodeHasChain) {
        // One of the inner node produces a chain.
        assert(!NodeHasOutFlag && "Node has flag but not chain!");
        ReplaceFroms.push_back("SDValue(N, " +
                               utostr(NumPatResults) + ")");
        ReplaceTos.push_back(ChainName);
      }
    }
    
    if (ChainAssignmentNeeded) {
      // Remember which op produces the chain.
      std::string ChainAssign;
      if (!isRoot)
        ChainAssign = ChainName + " = SDValue(" + NodeName +
        ".getNode(), " + utostr(NumResults+NumDstRegs) + ");";
      else
        ChainAssign = ChainName + " = SDValue(" + NodeName +
        ", " + utostr(NumResults+NumDstRegs) + ");";
      
      After.push_front(ChainAssign);
    }
    
    if (ReplaceFroms.size() == 1) {
      After.push_back("ReplaceUses(" + ReplaceFroms[0] + ", " +
                      ReplaceTos[0] + ");");
    } else if (!ReplaceFroms.empty()) {
      After.push_back("const SDValue Froms[] = {");
      for (unsigned i = 0, e = ReplaceFroms.size(); i != e; ++i)
        After.push_back("  " + ReplaceFroms[i] + (i + 1 != e ? "," : ""));
      After.push_back("};");
      After.push_back("const SDValue Tos[] = {");
      for (unsigned i = 0, e = ReplaceFroms.size(); i != e; ++i)
        After.push_back("  " + ReplaceTos[i] + (i + 1 != e ? "," : ""));
      After.push_back("};");
      After.push_back("ReplaceUses(Froms, Tos, " +
                      itostr(ReplaceFroms.size()) + ");");
    }
    
    // We prefer to use SelectNodeTo since it avoids allocation when
    // possible and it avoids CSE map recalculation for the node's
    // users, however it's tricky to use in a non-root context.
    //
    // We also don't use SelectNodeTo if the pattern replacement is being
    // used to jettison a chain result, since morphing the node in place
    // would leave users of the chain dangling.
    //
    if (!isRoot || (InputHasChain && !NodeHasChain)) {
      Code = "CurDAG->getMachineNode(" + Code;
    } else {
      Code = "CurDAG->SelectNodeTo(N, " + Code;
    }
    if (isRoot) {
      if (After.empty())
        CodePrefix = "return ";
      else
        After.push_back("return ResNode;");
    }
    
    emitCode(CodePrefix + Code + ");");
    
    if (GenDebug) {
      if (!isRoot) {
        emitCode("CurDAG->setSubgraphColor(" +
                 NodeName +".getNode(), \"yellow\");");
        emitCode("CurDAG->setSubgraphColor(" +
                 NodeName +".getNode(), \"black\");");
      } else {
        emitCode("CurDAG->setSubgraphColor(" + NodeName +", \"yellow\");");
        emitCode("CurDAG->setSubgraphColor(" + NodeName +", \"black\");");
      }
    }
    
    for (unsigned i = 0, e = After.size(); i != e; ++i)
      emitCode(After[i]);
    
    return NodeOps;
  }
  if (Op->isSubClassOf("SDNodeXForm")) {
    assert(N->getNumChildren() == 1 && "node xform should have one child!");
    // PatLeaf node - the operand may or may not be a leaf node. But it should
    // behave like one.
    std::vector<std::string> Ops =
    EmitResultCode(N->getChild(0), DstRegs, InFlagDecled,
                   ResNodeDecled, true);
    unsigned ResNo = TmpNo++;
    emitCode("SDValue Tmp" + utostr(ResNo) + " = Transform_" + Op->getName()
             + "(" + Ops.back() + ".getNode());");
    NodeOps.push_back("Tmp" + utostr(ResNo));
    if (isRoot)
      emitCode("return Tmp" + utostr(ResNo) + ".getNode();");
    return NodeOps;
  }
  
  N->dump();
  errs() << "\n";
  throw std::string("Unknown node in result pattern!");
}


/// EmitCodeForPattern - Given a pattern to match, emit code to the specified
/// stream to match the pattern, and generate the code for the match if it
/// succeeds.  Returns true if the pattern is not guaranteed to match.
void DAGISelEmitter::GenerateCodeForPattern(const PatternToMatch &Pattern,
                  std::vector<std::pair<unsigned, std::string> > &GeneratedCode,
                                           std::set<std::string> &GeneratedDecl,
                                        std::vector<std::string> &TargetOpcodes,
                                            std::vector<std::string> &TargetVTs,
                                            bool &OutputIsVariadic,
                                            unsigned &NumInputRootOps) {
  OutputIsVariadic = false;
  NumInputRootOps = 0;

  PatternCodeEmitter Emitter(CGP, Pattern.getPredicateCheck(),
                             Pattern.getSrcPattern(), Pattern.getDstPattern(),
                             GeneratedCode, GeneratedDecl,
                             TargetOpcodes, TargetVTs,
                             OutputIsVariadic, NumInputRootOps);

  // Emit the matcher, capturing named arguments in VariableMap.
  bool FoundChain = false;
  Emitter.EmitMatchCode(Pattern.getSrcPattern(), NULL, "N", "", FoundChain);

  // TP - Get *SOME* tree pattern, we don't care which.  It is only used for
  // diagnostics, which we know are impossible at this point.
  TreePattern &TP = *CGP.pf_begin()->second;
  
  // At this point, we know that we structurally match the pattern, but the
  // types of the nodes may not match.  Figure out the fewest number of type 
  // comparisons we need to emit.  For example, if there is only one integer
  // type supported by a target, there should be no type comparisons at all for
  // integer patterns!
  //
  // To figure out the fewest number of type checks needed, clone the pattern,
  // remove the types, then perform type inference on the pattern as a whole.
  // If there are unresolved types, emit an explicit check for those types,
  // apply the type to the tree, then rerun type inference.  Iterate until all
  // types are resolved.
  //
  TreePatternNode *Pat = Pattern.getSrcPattern()->clone();
  RemoveAllTypes(Pat);
  
  do {
    // Resolve/propagate as many types as possible.
    try {
      bool MadeChange = true;
      while (MadeChange)
        MadeChange = Pat->ApplyTypeConstraints(TP,
                                               true/*Ignore reg constraints*/);
    } catch (...) {
      assert(0 && "Error: could not find consistent types for something we"
             " already decided was ok!");
      abort();
    }

    // Insert a check for an unresolved type and add it to the tree.  If we find
    // an unresolved type to add a check for, this returns true and we iterate,
    // otherwise we are done.
  } while (Emitter.InsertOneTypeCheck(Pat, Pattern.getSrcPattern(), "N", true));

  Emitter.EmitResultCode(Pattern.getDstPattern(), Pattern.getDstRegs(),
                         false, false, false, true);
  delete Pat;
}

/// EraseCodeLine - Erase one code line from all of the patterns.  If removing
/// a line causes any of them to be empty, remove them and return true when
/// done.
static bool EraseCodeLine(std::vector<std::pair<const PatternToMatch*, 
                          std::vector<std::pair<unsigned, std::string> > > >
                          &Patterns) {
  bool ErasedPatterns = false;
  for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
    Patterns[i].second.pop_back();
    if (Patterns[i].second.empty()) {
      Patterns.erase(Patterns.begin()+i);
      --i; --e;
      ErasedPatterns = true;
    }
  }
  return ErasedPatterns;
}

/// EmitPatterns - Emit code for at least one pattern, but try to group common
/// code together between the patterns.
void DAGISelEmitter::EmitPatterns(std::vector<std::pair<const PatternToMatch*, 
                              std::vector<std::pair<unsigned, std::string> > > >
                                  &Patterns, unsigned Indent,
                                  raw_ostream &OS) {
  typedef std::pair<unsigned, std::string> CodeLine;
  typedef std::vector<CodeLine> CodeList;
  typedef std::vector<std::pair<const PatternToMatch*, CodeList> > PatternList;
  
  if (Patterns.empty()) return;
  
  // Figure out how many patterns share the next code line.  Explicitly copy
  // FirstCodeLine so that we don't invalidate a reference when changing
  // Patterns.
  const CodeLine FirstCodeLine = Patterns.back().second.back();
  unsigned LastMatch = Patterns.size()-1;
  while (LastMatch != 0 && Patterns[LastMatch-1].second.back() == FirstCodeLine)
    --LastMatch;
  
  // If not all patterns share this line, split the list into two pieces.  The
  // first chunk will use this line, the second chunk won't.
  if (LastMatch != 0) {
    PatternList Shared(Patterns.begin()+LastMatch, Patterns.end());
    PatternList Other(Patterns.begin(), Patterns.begin()+LastMatch);
    
    // FIXME: Emit braces?
    if (Shared.size() == 1) {
      const PatternToMatch &Pattern = *Shared.back().first;
      OS << "\n" << std::string(Indent, ' ') << "// Pattern: ";
      Pattern.getSrcPattern()->print(OS);
      OS << "\n" << std::string(Indent, ' ') << "// Emits: ";
      Pattern.getDstPattern()->print(OS);
      OS << "\n";
      unsigned AddedComplexity = Pattern.getAddedComplexity();
      OS << std::string(Indent, ' ') << "// Pattern complexity = "
         << getPatternSize(Pattern.getSrcPattern(), CGP) + AddedComplexity
         << "  cost = "
         << getResultPatternCost(Pattern.getDstPattern(), CGP)
         << "  size = "
         << getResultPatternSize(Pattern.getDstPattern(), CGP) << "\n";
    }
    if (FirstCodeLine.first != 1) {
      OS << std::string(Indent, ' ') << "{\n";
      Indent += 2;
    }
    EmitPatterns(Shared, Indent, OS);
    if (FirstCodeLine.first != 1) {
      Indent -= 2;
      OS << std::string(Indent, ' ') << "}\n";
    }
    
    if (Other.size() == 1) {
      const PatternToMatch &Pattern = *Other.back().first;
      OS << "\n" << std::string(Indent, ' ') << "// Pattern: ";
      Pattern.getSrcPattern()->print(OS);
      OS << "\n" << std::string(Indent, ' ') << "// Emits: ";
      Pattern.getDstPattern()->print(OS);
      OS << "\n";
      unsigned AddedComplexity = Pattern.getAddedComplexity();
      OS << std::string(Indent, ' ') << "// Pattern complexity = "
         << getPatternSize(Pattern.getSrcPattern(), CGP) + AddedComplexity
         << "  cost = "
         << getResultPatternCost(Pattern.getDstPattern(), CGP)
         << "  size = "
         << getResultPatternSize(Pattern.getDstPattern(), CGP) << "\n";
    }
    EmitPatterns(Other, Indent, OS);
    return;
  }
  
  // Remove this code from all of the patterns that share it.
  bool ErasedPatterns = EraseCodeLine(Patterns);
  
  bool isPredicate = FirstCodeLine.first == 1;
  
  // Otherwise, every pattern in the list has this line.  Emit it.
  if (!isPredicate) {
    // Normal code.
    OS << std::string(Indent, ' ') << FirstCodeLine.second << "\n";
  } else {
    OS << std::string(Indent, ' ') << "if (" << FirstCodeLine.second;
    
    // If the next code line is another predicate, and if all of the pattern
    // in this group share the same next line, emit it inline now.  Do this
    // until we run out of common predicates.
    while (!ErasedPatterns && Patterns.back().second.back().first == 1) {
      // Check that all of the patterns in Patterns end with the same predicate.
      bool AllEndWithSamePredicate = true;
      for (unsigned i = 0, e = Patterns.size(); i != e; ++i)
        if (Patterns[i].second.back() != Patterns.back().second.back()) {
          AllEndWithSamePredicate = false;
          break;
        }
      // If all of the predicates aren't the same, we can't share them.
      if (!AllEndWithSamePredicate) break;
      
      // Otherwise we can.  Emit it shared now.
      OS << " &&\n" << std::string(Indent+4, ' ')
         << Patterns.back().second.back().second;
      ErasedPatterns = EraseCodeLine(Patterns);
    }
    
    OS << ") {\n";
    Indent += 2;
  }
  
  EmitPatterns(Patterns, Indent, OS);
  
  if (isPredicate)
    OS << std::string(Indent-2, ' ') << "}\n";
}

static std::string getLegalCName(std::string OpName) {
  std::string::size_type pos = OpName.find("::");
  if (pos != std::string::npos)
    OpName.replace(pos, 2, "_");
  return OpName;
}

void DAGISelEmitter::EmitInstructionSelector(raw_ostream &OS) {
  const CodeGenTarget &Target = CGP.getTargetInfo();
  
  // Get the namespace to insert instructions into.
  std::string InstNS = Target.getInstNamespace();
  if (!InstNS.empty()) InstNS += "::";
  
  // Group the patterns by their top-level opcodes.
  std::map<std::string, std::vector<const PatternToMatch*> > PatternsByOpcode;
  // All unique target node emission functions.
  std::map<std::string, unsigned> EmitFunctions;
  for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(),
       E = CGP.ptm_end(); I != E; ++I) {
    const PatternToMatch &Pattern = *I;
    
    TreePatternNode *Node = Pattern.getSrcPattern();
    if (!Node->isLeaf()) {
      PatternsByOpcode[getOpcodeName(Node->getOperator(), CGP)].
        push_back(&Pattern);
    } else {
      const ComplexPattern *CP;
      if (dynamic_cast<IntInit*>(Node->getLeafValue())) {
        PatternsByOpcode[getOpcodeName(CGP.getSDNodeNamed("imm"), CGP)].
          push_back(&Pattern);
      } else if ((CP = NodeGetComplexPattern(Node, CGP))) {
        std::vector<Record*> OpNodes = CP->getRootNodes();
        for (unsigned j = 0, e = OpNodes.size(); j != e; j++) {
          PatternsByOpcode[getOpcodeName(OpNodes[j], CGP)]
            .insert(PatternsByOpcode[getOpcodeName(OpNodes[j], CGP)].begin(),
                    &Pattern);
        }
      } else {
        errs() << "Unrecognized opcode '";
        Node->dump();
        errs() << "' on tree pattern '";
        errs() << Pattern.getDstPattern()->getOperator()->getName() << "'!\n";
        exit(1);
      }
    }
  }

  // For each opcode, there might be multiple select functions, one per
  // ValueType of the node (or its first operand if it doesn't produce a
  // non-chain result.
  std::map<std::string, std::vector<std::string> > OpcodeVTMap;

  // Emit one Select_* method for each top-level opcode.  We do this instead of
  // emitting one giant switch statement to support compilers where this will
  // result in the recursive functions taking less stack space.
  for (std::map<std::string, std::vector<const PatternToMatch*> >::iterator
         PBOI = PatternsByOpcode.begin(), E = PatternsByOpcode.end();
       PBOI != E; ++PBOI) {
    const std::string &OpName = PBOI->first;
    std::vector<const PatternToMatch*> &PatternsOfOp = PBOI->second;
    assert(!PatternsOfOp.empty() && "No patterns but map has entry?");

    // Split them into groups by type.
    std::map<MVT::SimpleValueType,
             std::vector<const PatternToMatch*> > PatternsByType;
    for (unsigned i = 0, e = PatternsOfOp.size(); i != e; ++i) {
      const PatternToMatch *Pat = PatternsOfOp[i];
      TreePatternNode *SrcPat = Pat->getSrcPattern();
      PatternsByType[SrcPat->getTypeNum(0)].push_back(Pat);
    }

    for (std::map<MVT::SimpleValueType,
                  std::vector<const PatternToMatch*> >::iterator
           II = PatternsByType.begin(), EE = PatternsByType.end(); II != EE;
         ++II) {
      MVT::SimpleValueType OpVT = II->first;
      std::vector<const PatternToMatch*> &Patterns = II->second;
      typedef std::pair<unsigned, std::string> CodeLine;
      typedef std::vector<CodeLine> CodeList;
      typedef CodeList::iterator CodeListI;
    
      std::vector<std::pair<const PatternToMatch*, CodeList> > CodeForPatterns;
      std::vector<std::vector<std::string> > PatternOpcodes;
      std::vector<std::vector<std::string> > PatternVTs;
      std::vector<std::set<std::string> > PatternDecls;
      std::vector<bool> OutputIsVariadicFlags;
      std::vector<unsigned> NumInputRootOpsCounts;
      for (unsigned i = 0, e = Patterns.size(); i != e; ++i) {
        CodeList GeneratedCode;
        std::set<std::string> GeneratedDecl;
        std::vector<std::string> TargetOpcodes;
        std::vector<std::string> TargetVTs;
        bool OutputIsVariadic;
        unsigned NumInputRootOps;
        GenerateCodeForPattern(*Patterns[i], GeneratedCode, GeneratedDecl,
                               TargetOpcodes, TargetVTs,
                               OutputIsVariadic, NumInputRootOps);
        CodeForPatterns.push_back(std::make_pair(Patterns[i], GeneratedCode));
        PatternDecls.push_back(GeneratedDecl);
        PatternOpcodes.push_back(TargetOpcodes);
        PatternVTs.push_back(TargetVTs);
        OutputIsVariadicFlags.push_back(OutputIsVariadic);
        NumInputRootOpsCounts.push_back(NumInputRootOps);
      }
    
      // Factor target node emission code (emitted by EmitResultCode) into
      // separate functions. Uniquing and share them among all instruction
      // selection routines.
      for (unsigned i = 0, e = CodeForPatterns.size(); i != e; ++i) {
        CodeList &GeneratedCode = CodeForPatterns[i].second;
        std::vector<std::string> &TargetOpcodes = PatternOpcodes[i];
        std::vector<std::string> &TargetVTs = PatternVTs[i];
        std::set<std::string> Decls = PatternDecls[i];
        bool OutputIsVariadic = OutputIsVariadicFlags[i];
        unsigned NumInputRootOps = NumInputRootOpsCounts[i];
        std::vector<std::string> AddedInits;
        int CodeSize = (int)GeneratedCode.size();
        int LastPred = -1;
        for (int j = CodeSize-1; j >= 0; --j) {
          if (LastPred == -1 && GeneratedCode[j].first == 1)
            LastPred = j;
          else if (LastPred != -1 && GeneratedCode[j].first == 2)
            AddedInits.push_back(GeneratedCode[j].second);
        }

        std::string CalleeCode = "(SDNode *N";
        std::string CallerCode = "(N";
        for (unsigned j = 0, e = TargetOpcodes.size(); j != e; ++j) {
          CalleeCode += ", unsigned Opc" + utostr(j);
          CallerCode += ", " + TargetOpcodes[j];
        }
        for (unsigned j = 0, e = TargetVTs.size(); j != e; ++j) {
          CalleeCode += ", MVT::SimpleValueType VT" + utostr(j);
          CallerCode += ", " + TargetVTs[j];
        }
        for (std::set<std::string>::iterator
               I = Decls.begin(), E = Decls.end(); I != E; ++I) {
          std::string Name = *I;
          CalleeCode += ", SDValue &" + Name;
          CallerCode += ", " + Name;
        }

        if (OutputIsVariadic) {
          CalleeCode += ", unsigned NumInputRootOps";
          CallerCode += ", " + utostr(NumInputRootOps);
        }

        CallerCode += ");";
        CalleeCode += ") {\n";

        for (std::vector<std::string>::const_reverse_iterator
               I = AddedInits.rbegin(), E = AddedInits.rend(); I != E; ++I)
          CalleeCode += "  " + *I + "\n";

        for (int j = LastPred+1; j < CodeSize; ++j)
          CalleeCode += "  " + GeneratedCode[j].second + "\n";
        for (int j = LastPred+1; j < CodeSize; ++j)
          GeneratedCode.pop_back();
        CalleeCode += "}\n";

        // Uniquing the emission routines.
        unsigned EmitFuncNum;
        std::map<std::string, unsigned>::iterator EFI =
          EmitFunctions.find(CalleeCode);
        if (EFI != EmitFunctions.end()) {
          EmitFuncNum = EFI->second;
        } else {
          EmitFuncNum = EmitFunctions.size();
          EmitFunctions.insert(std::make_pair(CalleeCode, EmitFuncNum));
          // Prevent emission routines from being inlined to reduce selection
          // routines stack frame sizes.
          OS << "DISABLE_INLINE ";
          OS << "SDNode *Emit_" << utostr(EmitFuncNum) << CalleeCode;
        }

        // Replace the emission code within selection routines with calls to the
        // emission functions.
        if (GenDebug)
          GeneratedCode.push_back(std::make_pair(0, "CurDAG->setSubgraphColor(N, \"red\");"));
        CallerCode = "SDNode *Result = Emit_" + utostr(EmitFuncNum) + CallerCode;
        GeneratedCode.push_back(std::make_pair(3, CallerCode));
        if (GenDebug) {
          GeneratedCode.push_back(std::make_pair(0, "if(Result) {"));
          GeneratedCode.push_back(std::make_pair(0, "  CurDAG->setSubgraphColor(Result, \"yellow\");"));
          GeneratedCode.push_back(std::make_pair(0, "  CurDAG->setSubgraphColor(Result, \"black\");"));
          GeneratedCode.push_back(std::make_pair(0, "}"));
          //GeneratedCode.push_back(std::make_pair(0, "CurDAG->setSubgraphColor(N, \"black\");"));
        }
        GeneratedCode.push_back(std::make_pair(0, "return Result;"));
      }

      // Print function.
      std::string OpVTStr;
      if (OpVT == MVT::iPTR) {
        OpVTStr = "_iPTR";
      } else if (OpVT == MVT::iPTRAny) {
        OpVTStr = "_iPTRAny";
      } else if (OpVT == MVT::isVoid) {
        // Nodes with a void result actually have a first result type of either
        // Other (a chain) or Flag.  Since there is no one-to-one mapping from
        // void to this case, we handle it specially here.
      } else {
        OpVTStr = "_" + getEnumName(OpVT).substr(5);  // Skip 'MVT::'
      }
      std::map<std::string, std::vector<std::string> >::iterator OpVTI =
        OpcodeVTMap.find(OpName);
      if (OpVTI == OpcodeVTMap.end()) {
        std::vector<std::string> VTSet;
        VTSet.push_back(OpVTStr);
        OpcodeVTMap.insert(std::make_pair(OpName, VTSet));
      } else
        OpVTI->second.push_back(OpVTStr);

      // We want to emit all of the matching code now.  However, we want to emit
      // the matches in order of minimal cost.  Sort the patterns so the least
      // cost one is at the start.
      std::stable_sort(CodeForPatterns.begin(), CodeForPatterns.end(),
                       PatternSortingPredicate(CGP));

      // Scan the code to see if all of the patterns are reachable and if it is
      // possible that the last one might not match.
      bool mightNotMatch = true;
      for (unsigned i = 0, e = CodeForPatterns.size(); i != e; ++i) {
        CodeList &GeneratedCode = CodeForPatterns[i].second;
        mightNotMatch = false;

        for (unsigned j = 0, e = GeneratedCode.size(); j != e; ++j) {
          if (GeneratedCode[j].first == 1) { // predicate.
            mightNotMatch = true;
            break;
          }
        }
      
        // If this pattern definitely matches, and if it isn't the last one, the
        // patterns after it CANNOT ever match.  Error out.
        if (mightNotMatch == false && i != CodeForPatterns.size()-1) {
          errs() << "Pattern '";
          CodeForPatterns[i].first->getSrcPattern()->print(errs());
          errs() << "' is impossible to select!\n";
          exit(1);
        }
      }

      // Loop through and reverse all of the CodeList vectors, as we will be
      // accessing them from their logical front, but accessing the end of a
      // vector is more efficient.
      for (unsigned i = 0, e = CodeForPatterns.size(); i != e; ++i) {
        CodeList &GeneratedCode = CodeForPatterns[i].second;
        std::reverse(GeneratedCode.begin(), GeneratedCode.end());
      }
    
      // Next, reverse the list of patterns itself for the same reason.
      std::reverse(CodeForPatterns.begin(), CodeForPatterns.end());
    
      OS << "SDNode *Select_" << getLegalCName(OpName)
         << OpVTStr << "(SDNode *N) {\n";

      // Emit all of the patterns now, grouped together to share code.
      EmitPatterns(CodeForPatterns, 2, OS);
    
      // If the last pattern has predicates (which could fail) emit code to
      // catch the case where nothing handles a pattern.
      if (mightNotMatch) {
        OS << "\n";
        if (OpName != "ISD::INTRINSIC_W_CHAIN" &&
            OpName != "ISD::INTRINSIC_WO_CHAIN" &&
            OpName != "ISD::INTRINSIC_VOID")
          OS << "  CannotYetSelect(N);\n";
        else
          OS << "  CannotYetSelectIntrinsic(N);\n";

        OS << "  return NULL;\n";
      }
      OS << "}\n\n";
    }
  }
  
  OS << "// The main instruction selector code.\n"
     << "SDNode *SelectCode(SDNode *N) {\n"
     << "  MVT::SimpleValueType NVT = N->getValueType(0).getSimpleVT().SimpleTy;\n"
     << "  switch (N->getOpcode()) {\n"
     << "  default:\n"
     << "    assert(!N->isMachineOpcode() && \"Node already selected!\");\n"
     << "    break;\n"
     << "  case ISD::EntryToken:       // These nodes remain the same.\n"
     << "  case ISD::BasicBlock:\n"
     << "  case ISD::Register:\n"
     << "  case ISD::HANDLENODE:\n"
     << "  case ISD::TargetConstant:\n"
     << "  case ISD::TargetConstantFP:\n"
     << "  case ISD::TargetConstantPool:\n"
     << "  case ISD::TargetFrameIndex:\n"
     << "  case ISD::TargetExternalSymbol:\n"
     << "  case ISD::TargetBlockAddress:\n"
     << "  case ISD::TargetJumpTable:\n"
     << "  case ISD::TargetGlobalTLSAddress:\n"
     << "  case ISD::TargetGlobalAddress:\n"
     << "  case ISD::TokenFactor:\n"
     << "  case ISD::CopyFromReg:\n"
     << "  case ISD::CopyToReg: {\n"
     << "    return NULL;\n"
     << "  }\n"
     << "  case ISD::AssertSext:\n"
     << "  case ISD::AssertZext: {\n"
     << "    ReplaceUses(SDValue(N, 0), N->getOperand(0));\n"
     << "    return NULL;\n"
     << "  }\n"
     << "  case ISD::INLINEASM: return Select_INLINEASM(N);\n"
     << "  case ISD::EH_LABEL: return Select_EH_LABEL(N);\n"
     << "  case ISD::UNDEF: return Select_UNDEF(N);\n";

  // Loop over all of the case statements, emiting a call to each method we
  // emitted above.
  for (std::map<std::string, std::vector<const PatternToMatch*> >::iterator
         PBOI = PatternsByOpcode.begin(), E = PatternsByOpcode.end();
       PBOI != E; ++PBOI) {
    const std::string &OpName = PBOI->first;
    // Potentially multiple versions of select for this opcode. One for each
    // ValueType of the node (or its first true operand if it doesn't produce a
    // result.
    std::map<std::string, std::vector<std::string> >::iterator OpVTI =
      OpcodeVTMap.find(OpName);
    std::vector<std::string> &OpVTs = OpVTI->second;
    OS << "  case " << OpName << ": {\n";
    // If we have only one variant and it's the default, elide the
    // switch.  Marginally faster, and makes MSVC happier.
    if (OpVTs.size()==1 && OpVTs[0].empty()) {
      OS << "    return Select_" << getLegalCName(OpName) << "(N);\n";
      OS << "    break;\n";
      OS << "  }\n";
      continue;
    }
    // Keep track of whether we see a pattern that has an iPtr result.
    bool HasPtrPattern = false;
    bool HasDefaultPattern = false;
      
    OS << "    switch (NVT) {\n";
    for (unsigned i = 0, e = OpVTs.size(); i < e; ++i) {
      std::string &VTStr = OpVTs[i];
      if (VTStr.empty()) {
        HasDefaultPattern = true;
        continue;
      }

      // If this is a match on iPTR: don't emit it directly, we need special
      // code.
      if (VTStr == "_iPTR") {
        HasPtrPattern = true;
        continue;
      }
      OS << "    case MVT::" << VTStr.substr(1) << ":\n"
         << "      return Select_" << getLegalCName(OpName)
         << VTStr << "(N);\n";
    }
    OS << "    default:\n";
      
    // If there is an iPTR result version of this pattern, emit it here.
    if (HasPtrPattern) {
      OS << "      if (TLI.getPointerTy() == NVT)\n";
      OS << "        return Select_" << getLegalCName(OpName) <<"_iPTR(N);\n";
    }
    if (HasDefaultPattern) {
      OS << "      return Select_" << getLegalCName(OpName) << "(N);\n";
    }
    OS << "      break;\n";
    OS << "    }\n";
    OS << "    break;\n";
    OS << "  }\n";
  }

  OS << "  } // end of big switch.\n\n"
     << "  if (N->getOpcode() != ISD::INTRINSIC_W_CHAIN &&\n"
     << "      N->getOpcode() != ISD::INTRINSIC_WO_CHAIN &&\n"
     << "      N->getOpcode() != ISD::INTRINSIC_VOID) {\n"
     << "    CannotYetSelect(N);\n"
     << "  } else {\n"
     << "    CannotYetSelectIntrinsic(N);\n"
     << "  }\n"
     << "  return NULL;\n"
     << "}\n\n";
}

void DAGISelEmitter::run(raw_ostream &OS) {
  EmitSourceFileHeader("DAG Instruction Selector for the " +
                       CGP.getTargetInfo().getName() + " target", OS);
  
  OS << "// *** NOTE: This file is #included into the middle of the target\n"
     << "// *** instruction selector class.  These functions are really "
     << "methods.\n\n";

  OS << "// Include standard, target-independent definitions and methods used\n"
     << "// by the instruction selector.\n";
  OS << "#include \"llvm/CodeGen/DAGISelHeader.h\"\n\n";
  
  EmitNodeTransforms(OS);
  EmitPredicateFunctions(OS);
  
  DEBUG(errs() << "\n\nALL PATTERNS TO MATCH:\n\n");
  for (CodeGenDAGPatterns::ptm_iterator I = CGP.ptm_begin(), E = CGP.ptm_end();
       I != E; ++I) {
    DEBUG(errs() << "PATTERN: ";   I->getSrcPattern()->dump());
    DEBUG(errs() << "\nRESULT:  "; I->getDstPattern()->dump());
    DEBUG(errs() << "\n");
  }
  
  // At this point, we have full information about the 'Patterns' we need to
  // parse, both implicitly from instructions as well as from explicit pattern
  // definitions.  Emit the resultant instruction selector.
  EmitInstructionSelector(OS);  
  
}