llvm-project/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.cpp

//===-- llvm/CodeGen/DwarfDebug.cpp - Dwarf Debug Framework ---------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains support for writing dwarf debug info into asm files.
//
//===----------------------------------------------------------------------===//

#include "DwarfDebug.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/MC/MCSection.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include "llvm/Target/TargetRegisterInfo.h"
#include "llvm/Support/Timer.h"
#include "llvm/System/Path.h"
using namespace llvm;

static TimerGroup &getDwarfTimerGroup() {
  static TimerGroup DwarfTimerGroup("Dwarf Debugging");
  return DwarfTimerGroup;
}

//===----------------------------------------------------------------------===//

/// Configuration values for initial hash set sizes (log2).
///
static const unsigned InitDiesSetSize          = 9; // log2(512)
static const unsigned InitAbbreviationsSetSize = 9; // log2(512)
static const unsigned InitValuesSetSize        = 9; // log2(512)

namespace llvm {

//===----------------------------------------------------------------------===//
/// CompileUnit - This dwarf writer support class manages information associate
/// with a source file.
class VISIBILITY_HIDDEN CompileUnit {
  /// ID - File identifier for source.
  ///
  unsigned ID;

  /// Die - Compile unit debug information entry.
  ///
  DIE *Die;

  /// GVToDieMap - Tracks the mapping of unit level debug informaton
  /// variables to debug information entries.
  std::map<GlobalVariable *, DIE *> GVToDieMap;

  /// GVToDIEEntryMap - Tracks the mapping of unit level debug informaton
  /// descriptors to debug information entries using a DIEEntry proxy.
  std::map<GlobalVariable *, DIEEntry *> GVToDIEEntryMap;

  /// Globals - A map of globally visible named entities for this unit.
  ///
  StringMap<DIE*> Globals;

  /// DiesSet - Used to uniquely define dies within the compile unit.
  ///
  FoldingSet<DIE> DiesSet;
public:
  CompileUnit(unsigned I, DIE *D)
    : ID(I), Die(D), DiesSet(InitDiesSetSize) {}
  ~CompileUnit() { delete Die; }

  // Accessors.
  unsigned getID() const { return ID; }
  DIE* getDie() const { return Die; }
  StringMap<DIE*> &getGlobals() { return Globals; }

  /// hasContent - Return true if this compile unit has something to write out.
  ///
  bool hasContent() const { return !Die->getChildren().empty(); }

  /// AddGlobal - Add a new global entity to the compile unit.
  ///
  void AddGlobal(const std::string &Name, DIE *Die) { Globals[Name] = Die; }

  /// getDieMapSlotFor - Returns the debug information entry map slot for the
  /// specified debug variable.
  DIE *&getDieMapSlotFor(GlobalVariable *GV) { return GVToDieMap[GV]; }

  /// getDIEEntrySlotFor - Returns the debug information entry proxy slot for
  /// the specified debug variable.
  DIEEntry *&getDIEEntrySlotFor(GlobalVariable *GV) {
    return GVToDIEEntryMap[GV];
  }

  /// AddDie - Adds or interns the DIE to the compile unit.
  ///
  DIE *AddDie(DIE &Buffer) {
    FoldingSetNodeID ID;
    Buffer.Profile(ID);
    void *Where;
    DIE *Die = DiesSet.FindNodeOrInsertPos(ID, Where);

    if (!Die) {
      Die = new DIE(Buffer);
      DiesSet.InsertNode(Die, Where);
      this->Die->AddChild(Die);
      Buffer.Detach();
    }

    return Die;
  }
};

//===----------------------------------------------------------------------===//
/// DbgVariable - This class is used to track local variable information.
///
class VISIBILITY_HIDDEN DbgVariable {
  DIVariable Var;                    // Variable Descriptor.
  unsigned FrameIndex;               // Variable frame index.
  bool InlinedFnVar;                 // Variable for an inlined function.
public:
  DbgVariable(DIVariable V, unsigned I, bool IFV)
    : Var(V), FrameIndex(I), InlinedFnVar(IFV)  {}

  // Accessors.
  DIVariable getVariable() const { return Var; }
  unsigned getFrameIndex() const { return FrameIndex; }
  bool isInlinedFnVar() const { return InlinedFnVar; }
};

//===----------------------------------------------------------------------===//
/// DbgScope - This class is used to track scope information.
///
class DbgConcreteScope;
class VISIBILITY_HIDDEN DbgScope {
  DbgScope *Parent;                   // Parent to this scope.
  DIDescriptor Desc;                  // Debug info descriptor for scope.
                                      // Either subprogram or block.
  unsigned StartLabelID;              // Label ID of the beginning of scope.
  unsigned EndLabelID;                // Label ID of the end of scope.
  SmallVector<DbgScope *, 4> Scopes;  // Scopes defined in scope.
  SmallVector<DbgVariable *, 8> Variables;// Variables declared in scope.
  SmallVector<DbgConcreteScope *, 8> ConcreteInsts;// Concrete insts of funcs.
  
  // Private state for dump()
  mutable unsigned IndentLevel;
public:
  DbgScope(DbgScope *P, DIDescriptor D)
    : Parent(P), Desc(D), StartLabelID(0), EndLabelID(0), IndentLevel(0) {}
  virtual ~DbgScope();

  // Accessors.
  DbgScope *getParent()          const { return Parent; }
  DIDescriptor getDesc()         const { return Desc; }
  unsigned getStartLabelID()     const { return StartLabelID; }
  unsigned getEndLabelID()       const { return EndLabelID; }
  SmallVector<DbgScope *, 4> &getScopes() { return Scopes; }
  SmallVector<DbgVariable *, 8> &getVariables() { return Variables; }
  SmallVector<DbgConcreteScope*,8> &getConcreteInsts() { return ConcreteInsts; }
  void setStartLabelID(unsigned S) { StartLabelID = S; }
  void setEndLabelID(unsigned E)   { EndLabelID = E; }

  /// AddScope - Add a scope to the scope.
  ///
  void AddScope(DbgScope *S) { Scopes.push_back(S); }

  /// AddVariable - Add a variable to the scope.
  ///
  void AddVariable(DbgVariable *V) { Variables.push_back(V); }

  /// AddConcreteInst - Add a concrete instance to the scope.
  ///
  void AddConcreteInst(DbgConcreteScope *C) { ConcreteInsts.push_back(C); }

#ifndef NDEBUG
  void dump() const;
#endif
};

#ifndef NDEBUG
void DbgScope::dump() const {
  std::string Indent(IndentLevel, ' ');

  cerr << Indent; Desc.dump();
  cerr << " [" << StartLabelID << ", " << EndLabelID << "]\n";

  IndentLevel += 2;

  for (unsigned i = 0, e = Scopes.size(); i != e; ++i)
    if (Scopes[i] != this)
      Scopes[i]->dump();

  IndentLevel -= 2;
}
#endif

//===----------------------------------------------------------------------===//
/// DbgConcreteScope - This class is used to track a scope that holds concrete
/// instance information.
///
class VISIBILITY_HIDDEN DbgConcreteScope : public DbgScope {
  CompileUnit *Unit;
  DIE *Die;                           // Debug info for this concrete scope.
public:
  DbgConcreteScope(DIDescriptor D) : DbgScope(NULL, D) {}

  // Accessors.
  DIE *getDie() const { return Die; }
  void setDie(DIE *D) { Die = D; }
};

DbgScope::~DbgScope() {
  for (unsigned i = 0, N = Scopes.size(); i < N; ++i)
    delete Scopes[i];
  for (unsigned j = 0, M = Variables.size(); j < M; ++j)
    delete Variables[j];
  for (unsigned k = 0, O = ConcreteInsts.size(); k < O; ++k)
    delete ConcreteInsts[k];
}

} // end llvm namespace

DwarfDebug::DwarfDebug(raw_ostream &OS, AsmPrinter *A, const TargetAsmInfo *T)
  : Dwarf(OS, A, T, "dbg"), ModuleCU(0),
    AbbreviationsSet(InitAbbreviationsSetSize), Abbreviations(),
    ValuesSet(InitValuesSetSize), Values(), StringPool(), 
    SectionSourceLines(), didInitial(false), shouldEmit(false),
    FunctionDbgScope(0), DebugTimer(0) {
  if (TimePassesIsEnabled)
    DebugTimer = new Timer("Dwarf Debug Writer",
                           getDwarfTimerGroup());
}
DwarfDebug::~DwarfDebug() {
  for (unsigned j = 0, M = Values.size(); j < M; ++j)
    delete Values[j];

  for (DenseMap<const GlobalVariable *, DbgScope *>::iterator
         I = AbstractInstanceRootMap.begin(),
         E = AbstractInstanceRootMap.end(); I != E;++I)
    delete I->second;

  delete DebugTimer;
}

/// AssignAbbrevNumber - Define a unique number for the abbreviation.
///
void DwarfDebug::AssignAbbrevNumber(DIEAbbrev &Abbrev) {
  // Profile the node so that we can make it unique.
  FoldingSetNodeID ID;
  Abbrev.Profile(ID);

  // Check the set for priors.
  DIEAbbrev *InSet = AbbreviationsSet.GetOrInsertNode(&Abbrev);

  // If it's newly added.
  if (InSet == &Abbrev) {
    // Add to abbreviation list.
    Abbreviations.push_back(&Abbrev);

    // Assign the vector position + 1 as its number.
    Abbrev.setNumber(Abbreviations.size());
  } else {
    // Assign existing abbreviation number.
    Abbrev.setNumber(InSet->getNumber());
  }
}

/// CreateDIEEntry - Creates a new DIEEntry to be a proxy for a debug
/// information entry.
DIEEntry *DwarfDebug::CreateDIEEntry(DIE *Entry) {
  DIEEntry *Value;

  if (Entry) {
    FoldingSetNodeID ID;
    DIEEntry::Profile(ID, Entry);
    void *Where;
    Value = static_cast<DIEEntry *>(ValuesSet.FindNodeOrInsertPos(ID, Where));

    if (Value) return Value;

    Value = new DIEEntry(Entry);
    ValuesSet.InsertNode(Value, Where);
  } else {
    Value = new DIEEntry(Entry);
  }

  Values.push_back(Value);
  return Value;
}

/// SetDIEEntry - Set a DIEEntry once the debug information entry is defined.
///
void DwarfDebug::SetDIEEntry(DIEEntry *Value, DIE *Entry) {
  Value->setEntry(Entry);

  // Add to values set if not already there.  If it is, we merely have a
  // duplicate in the values list (no harm.)
  ValuesSet.GetOrInsertNode(Value);
}

/// AddUInt - Add an unsigned integer attribute data and value.
///
void DwarfDebug::AddUInt(DIE *Die, unsigned Attribute,
                         unsigned Form, uint64_t Integer) {
  if (!Form) Form = DIEInteger::BestForm(false, Integer);

  FoldingSetNodeID ID;
  DIEInteger::Profile(ID, Integer);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = new DIEInteger(Integer);
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  }

  Die->AddValue(Attribute, Form, Value);
}

/// AddSInt - Add an signed integer attribute data and value.
///
void DwarfDebug::AddSInt(DIE *Die, unsigned Attribute,
                         unsigned Form, int64_t Integer) {
  if (!Form) Form = DIEInteger::BestForm(true, Integer);

  FoldingSetNodeID ID;
  DIEInteger::Profile(ID, (uint64_t)Integer);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = new DIEInteger(Integer);
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  }

  Die->AddValue(Attribute, Form, Value);
}

/// AddString - Add a string attribute data and value.
///
void DwarfDebug::AddString(DIE *Die, unsigned Attribute, unsigned Form,
                           const std::string &String) {
  FoldingSetNodeID ID;
  DIEString::Profile(ID, String);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = new DIEString(String);
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  }

  Die->AddValue(Attribute, Form, Value);
}

/// AddLabel - Add a Dwarf label attribute data and value.
///
void DwarfDebug::AddLabel(DIE *Die, unsigned Attribute, unsigned Form,
                          const DWLabel &Label) {
  FoldingSetNodeID ID;
  DIEDwarfLabel::Profile(ID, Label);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = new DIEDwarfLabel(Label);
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  }

  Die->AddValue(Attribute, Form, Value);
}

/// AddObjectLabel - Add an non-Dwarf label attribute data and value.
///
void DwarfDebug::AddObjectLabel(DIE *Die, unsigned Attribute, unsigned Form,
                                const std::string &Label) {
  FoldingSetNodeID ID;
  DIEObjectLabel::Profile(ID, Label);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = new DIEObjectLabel(Label);
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  }

  Die->AddValue(Attribute, Form, Value);
}

/// AddSectionOffset - Add a section offset label attribute data and value.
///
void DwarfDebug::AddSectionOffset(DIE *Die, unsigned Attribute, unsigned Form,
                                  const DWLabel &Label, const DWLabel &Section,
                                  bool isEH, bool useSet) {
  FoldingSetNodeID ID;
  DIESectionOffset::Profile(ID, Label, Section);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = new DIESectionOffset(Label, Section, isEH, useSet);
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  }

  Die->AddValue(Attribute, Form, Value);
}

/// AddDelta - Add a label delta attribute data and value.
///
void DwarfDebug::AddDelta(DIE *Die, unsigned Attribute, unsigned Form,
                          const DWLabel &Hi, const DWLabel &Lo) {
  FoldingSetNodeID ID;
  DIEDelta::Profile(ID, Hi, Lo);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = new DIEDelta(Hi, Lo);
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  }

  Die->AddValue(Attribute, Form, Value);
}

/// AddBlock - Add block data.
///
void DwarfDebug::AddBlock(DIE *Die, unsigned Attribute, unsigned Form,
                          DIEBlock *Block) {
  Block->ComputeSize(TD);
  FoldingSetNodeID ID;
  Block->Profile(ID);
  void *Where;
  DIEValue *Value = ValuesSet.FindNodeOrInsertPos(ID, Where);

  if (!Value) {
    Value = Block;
    ValuesSet.InsertNode(Value, Where);
    Values.push_back(Value);
  } else {
    // Already exists, reuse the previous one.
    delete Block;
    Block = cast<DIEBlock>(Value);
  }

  Die->AddValue(Attribute, Block->BestForm(), Value);
}

/// AddSourceLine - Add location information to specified debug information
/// entry.
void DwarfDebug::AddSourceLine(DIE *Die, const DIVariable *V) {
  // If there is no compile unit specified, don't add a line #.
  if (V->getCompileUnit().isNull())
    return;

  unsigned Line = V->getLineNumber();
  unsigned FileID = FindCompileUnit(V->getCompileUnit()).getID();
  assert(FileID && "Invalid file id");
  AddUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
  AddUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
}

/// AddSourceLine - Add location information to specified debug information
/// entry.
void DwarfDebug::AddSourceLine(DIE *Die, const DIGlobal *G) {
  // If there is no compile unit specified, don't add a line #.
  if (G->getCompileUnit().isNull())
    return;

  unsigned Line = G->getLineNumber();
  unsigned FileID = FindCompileUnit(G->getCompileUnit()).getID();
  assert(FileID && "Invalid file id");
  AddUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
  AddUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
}
void DwarfDebug::AddSourceLine(DIE *Die, const DIType *Ty) {
  // If there is no compile unit specified, don't add a line #.
  DICompileUnit CU = Ty->getCompileUnit();
  if (CU.isNull())
    return;

  unsigned Line = Ty->getLineNumber();
  unsigned FileID = FindCompileUnit(CU).getID();
  assert(FileID && "Invalid file id");
  AddUInt(Die, dwarf::DW_AT_decl_file, 0, FileID);
  AddUInt(Die, dwarf::DW_AT_decl_line, 0, Line);
}

/// AddAddress - Add an address attribute to a die based on the location
/// provided.
void DwarfDebug::AddAddress(DIE *Die, unsigned Attribute,
                            const MachineLocation &Location) {
  unsigned Reg = RI->getDwarfRegNum(Location.getReg(), false);
  DIEBlock *Block = new DIEBlock();

  if (Location.isReg()) {
    if (Reg < 32) {
      AddUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_reg0 + Reg);
    } else {
      AddUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_regx);
      AddUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
    }
  } else {
    if (Reg < 32) {
      AddUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_breg0 + Reg);
    } else {
      AddUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_bregx);
      AddUInt(Block, 0, dwarf::DW_FORM_udata, Reg);
    }

    AddUInt(Block, 0, dwarf::DW_FORM_sdata, Location.getOffset());
  }

  AddBlock(Die, Attribute, 0, Block);
}

/// AddType - Add a new type attribute to the specified entity.
void DwarfDebug::AddType(CompileUnit *DW_Unit, DIE *Entity, DIType Ty) {
  if (Ty.isNull())
    return;

  // Check for pre-existence.
  DIEEntry *&Slot = DW_Unit->getDIEEntrySlotFor(Ty.getGV());

  // If it exists then use the existing value.
  if (Slot) {
    Entity->AddValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, Slot);
    return;
  }

  // Set up proxy.
  Slot = CreateDIEEntry();

  // Construct type.
  DIE Buffer(dwarf::DW_TAG_base_type);
  if (Ty.isBasicType(Ty.getTag()))
    ConstructTypeDIE(DW_Unit, Buffer, DIBasicType(Ty.getGV()));
  else if (Ty.isDerivedType(Ty.getTag()))
    ConstructTypeDIE(DW_Unit, Buffer, DIDerivedType(Ty.getGV()));
  else {
    assert(Ty.isCompositeType(Ty.getTag()) && "Unknown kind of DIType");
    ConstructTypeDIE(DW_Unit, Buffer, DICompositeType(Ty.getGV()));
  }

  // Add debug information entry to entity and appropriate context.
  DIE *Die = NULL;
  DIDescriptor Context = Ty.getContext();
  if (!Context.isNull())
    Die = DW_Unit->getDieMapSlotFor(Context.getGV());

  if (Die) {
    DIE *Child = new DIE(Buffer);
    Die->AddChild(Child);
    Buffer.Detach();
    SetDIEEntry(Slot, Child);
  } else {
    Die = DW_Unit->AddDie(Buffer);
    SetDIEEntry(Slot, Die);
  }

  Entity->AddValue(dwarf::DW_AT_type, dwarf::DW_FORM_ref4, Slot);
}

/// ConstructTypeDIE - Construct basic type die from DIBasicType.
void DwarfDebug::ConstructTypeDIE(CompileUnit *DW_Unit, DIE &Buffer,
                                  DIBasicType BTy) {
  // Get core information.
  std::string Name;
  BTy.getName(Name);
  Buffer.setTag(dwarf::DW_TAG_base_type);
  AddUInt(&Buffer, dwarf::DW_AT_encoding,  dwarf::DW_FORM_data1,
          BTy.getEncoding());

  // Add name if not anonymous or intermediate type.
  if (!Name.empty())
    AddString(&Buffer, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
  uint64_t Size = BTy.getSizeInBits() >> 3;
  AddUInt(&Buffer, dwarf::DW_AT_byte_size, 0, Size);
}

/// ConstructTypeDIE - Construct derived type die from DIDerivedType.
void DwarfDebug::ConstructTypeDIE(CompileUnit *DW_Unit, DIE &Buffer,
                                  DIDerivedType DTy) {
  // Get core information.
  std::string Name;
  DTy.getName(Name);
  uint64_t Size = DTy.getSizeInBits() >> 3;
  unsigned Tag = DTy.getTag();

  // FIXME - Workaround for templates.
  if (Tag == dwarf::DW_TAG_inheritance) Tag = dwarf::DW_TAG_reference_type;

  Buffer.setTag(Tag);

  // Map to main type, void will not have a type.
  DIType FromTy = DTy.getTypeDerivedFrom();
  AddType(DW_Unit, &Buffer, FromTy);

  // Add name if not anonymous or intermediate type.
  if (!Name.empty())
    AddString(&Buffer, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);

  // Add size if non-zero (derived types might be zero-sized.)
  if (Size)
    AddUInt(&Buffer, dwarf::DW_AT_byte_size, 0, Size);

  // Add source line info if available and TyDesc is not a forward declaration.
  if (!DTy.isForwardDecl())
    AddSourceLine(&Buffer, &DTy);
}

/// ConstructTypeDIE - Construct type DIE from DICompositeType.
void DwarfDebug::ConstructTypeDIE(CompileUnit *DW_Unit, DIE &Buffer,
                                  DICompositeType CTy) {
  // Get core information.
  std::string Name;
  CTy.getName(Name);

  uint64_t Size = CTy.getSizeInBits() >> 3;
  unsigned Tag = CTy.getTag();
  Buffer.setTag(Tag);

  switch (Tag) {
  case dwarf::DW_TAG_vector_type:
  case dwarf::DW_TAG_array_type:
    ConstructArrayTypeDIE(DW_Unit, Buffer, &CTy);
    break;
  case dwarf::DW_TAG_enumeration_type: {
    DIArray Elements = CTy.getTypeArray();

    // Add enumerators to enumeration type.
    for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
      DIE *ElemDie = NULL;
      DIEnumerator Enum(Elements.getElement(i).getGV());
      ElemDie = ConstructEnumTypeDIE(DW_Unit, &Enum);
      Buffer.AddChild(ElemDie);
    }
  }
    break;
  case dwarf::DW_TAG_subroutine_type: {
    // Add return type.
    DIArray Elements = CTy.getTypeArray();
    DIDescriptor RTy = Elements.getElement(0);
    AddType(DW_Unit, &Buffer, DIType(RTy.getGV()));

    // Add prototype flag.
    AddUInt(&Buffer, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag, 1);

    // Add arguments.
    for (unsigned i = 1, N = Elements.getNumElements(); i < N; ++i) {
      DIE *Arg = new DIE(dwarf::DW_TAG_formal_parameter);
      DIDescriptor Ty = Elements.getElement(i);
      AddType(DW_Unit, Arg, DIType(Ty.getGV()));
      Buffer.AddChild(Arg);
    }
  }
    break;
  case dwarf::DW_TAG_structure_type:
  case dwarf::DW_TAG_union_type:
  case dwarf::DW_TAG_class_type: {
    // Add elements to structure type.
    DIArray Elements = CTy.getTypeArray();

    // A forward struct declared type may not have elements available.
    if (Elements.isNull())
      break;

    // Add elements to structure type.
    for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
      DIDescriptor Element = Elements.getElement(i);
      DIE *ElemDie = NULL;
      if (Element.getTag() == dwarf::DW_TAG_subprogram)
        ElemDie = CreateSubprogramDIE(DW_Unit,
                                      DISubprogram(Element.getGV()));
      else
        ElemDie = CreateMemberDIE(DW_Unit,
                                  DIDerivedType(Element.getGV()));
      Buffer.AddChild(ElemDie);
    }

    // FIXME: We'd like an API to register additional attributes for the
    // frontend to use while synthesizing, and then we'd use that api in clang
    // instead of this.
    if (Name == "__block_literal_generic")
      AddUInt(&Buffer, dwarf::DW_AT_APPLE_block, dwarf::DW_FORM_flag, 1);

    unsigned RLang = CTy.getRunTimeLang();
    if (RLang)
      AddUInt(&Buffer, dwarf::DW_AT_APPLE_runtime_class,
              dwarf::DW_FORM_data1, RLang);
    break;
  }
  default:
    break;
  }

  // Add name if not anonymous or intermediate type.
  if (!Name.empty())
    AddString(&Buffer, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);

  if (Tag == dwarf::DW_TAG_enumeration_type ||
      Tag == dwarf::DW_TAG_structure_type || Tag == dwarf::DW_TAG_union_type) {
    // Add size if non-zero (derived types might be zero-sized.)
    if (Size)
      AddUInt(&Buffer, dwarf::DW_AT_byte_size, 0, Size);
    else {
      // Add zero size if it is not a forward declaration.
      if (CTy.isForwardDecl())
        AddUInt(&Buffer, dwarf::DW_AT_declaration, dwarf::DW_FORM_flag, 1);
      else
        AddUInt(&Buffer, dwarf::DW_AT_byte_size, 0, 0);
    }

    // Add source line info if available.
    if (!CTy.isForwardDecl())
      AddSourceLine(&Buffer, &CTy);
  }
}

/// ConstructSubrangeDIE - Construct subrange DIE from DISubrange.
void DwarfDebug::ConstructSubrangeDIE(DIE &Buffer, DISubrange SR, DIE *IndexTy){
  int64_t L = SR.getLo();
  int64_t H = SR.getHi();
  DIE *DW_Subrange = new DIE(dwarf::DW_TAG_subrange_type);

  if (L != H) {
    AddDIEEntry(DW_Subrange, dwarf::DW_AT_type, dwarf::DW_FORM_ref4, IndexTy);
    if (L)
      AddSInt(DW_Subrange, dwarf::DW_AT_lower_bound, 0, L);
    AddSInt(DW_Subrange, dwarf::DW_AT_upper_bound, 0, H);
  }

  Buffer.AddChild(DW_Subrange);
}

/// ConstructArrayTypeDIE - Construct array type DIE from DICompositeType.
void DwarfDebug::ConstructArrayTypeDIE(CompileUnit *DW_Unit, DIE &Buffer,
                                       DICompositeType *CTy) {
  Buffer.setTag(dwarf::DW_TAG_array_type);
  if (CTy->getTag() == dwarf::DW_TAG_vector_type)
    AddUInt(&Buffer, dwarf::DW_AT_GNU_vector, dwarf::DW_FORM_flag, 1);

  // Emit derived type.
  AddType(DW_Unit, &Buffer, CTy->getTypeDerivedFrom());
  DIArray Elements = CTy->getTypeArray();

  // Construct an anonymous type for index type.
  DIE IdxBuffer(dwarf::DW_TAG_base_type);
  AddUInt(&IdxBuffer, dwarf::DW_AT_byte_size, 0, sizeof(int32_t));
  AddUInt(&IdxBuffer, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1,
          dwarf::DW_ATE_signed);
  DIE *IndexTy = DW_Unit->AddDie(IdxBuffer);

  // Add subranges to array type.
  for (unsigned i = 0, N = Elements.getNumElements(); i < N; ++i) {
    DIDescriptor Element = Elements.getElement(i);
    if (Element.getTag() == dwarf::DW_TAG_subrange_type)
      ConstructSubrangeDIE(Buffer, DISubrange(Element.getGV()), IndexTy);
  }
}

/// ConstructEnumTypeDIE - Construct enum type DIE from DIEnumerator.
DIE *DwarfDebug::ConstructEnumTypeDIE(CompileUnit *DW_Unit, DIEnumerator *ETy) {
  DIE *Enumerator = new DIE(dwarf::DW_TAG_enumerator);
  std::string Name;
  ETy->getName(Name);
  AddString(Enumerator, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
  int64_t Value = ETy->getEnumValue();
  AddSInt(Enumerator, dwarf::DW_AT_const_value, dwarf::DW_FORM_sdata, Value);
  return Enumerator;
}

/// CreateGlobalVariableDIE - Create new DIE using GV.
DIE *DwarfDebug::CreateGlobalVariableDIE(CompileUnit *DW_Unit,
                                         const DIGlobalVariable &GV) {
  DIE *GVDie = new DIE(dwarf::DW_TAG_variable);
  std::string Name;
  GV.getDisplayName(Name);
  AddString(GVDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
  std::string LinkageName;
  GV.getLinkageName(LinkageName);
  if (!LinkageName.empty()) {
    // Skip special LLVM prefix that is used to inform the asm printer to not emit
    // usual symbol prefix before the symbol name. This happens for Objective-C
    // symbol names and symbol whose name is replaced using GCC's __asm__ attribute.
    if (LinkageName[0] == 1)
      LinkageName = &LinkageName[1];
    AddString(GVDie, dwarf::DW_AT_MIPS_linkage_name, dwarf::DW_FORM_string,
              LinkageName);
  }
    AddType(DW_Unit, GVDie, GV.getType());
  if (!GV.isLocalToUnit())
    AddUInt(GVDie, dwarf::DW_AT_external, dwarf::DW_FORM_flag, 1);
  AddSourceLine(GVDie, &GV);
  return GVDie;
}

/// CreateMemberDIE - Create new member DIE.
DIE *DwarfDebug::CreateMemberDIE(CompileUnit *DW_Unit, const DIDerivedType &DT){
  DIE *MemberDie = new DIE(DT.getTag());
  std::string Name;
  DT.getName(Name);
  if (!Name.empty())
    AddString(MemberDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);

  AddType(DW_Unit, MemberDie, DT.getTypeDerivedFrom());

  AddSourceLine(MemberDie, &DT);

  uint64_t Size = DT.getSizeInBits();
  uint64_t FieldSize = DT.getOriginalTypeSize();

  if (Size != FieldSize) {
    // Handle bitfield.
    AddUInt(MemberDie, dwarf::DW_AT_byte_size, 0, DT.getOriginalTypeSize()>>3);
    AddUInt(MemberDie, dwarf::DW_AT_bit_size, 0, DT.getSizeInBits());

    uint64_t Offset = DT.getOffsetInBits();
    uint64_t FieldOffset = Offset;
    uint64_t AlignMask = ~(DT.getAlignInBits() - 1);
    uint64_t HiMark = (Offset + FieldSize) & AlignMask;
    FieldOffset = (HiMark - FieldSize);
    Offset -= FieldOffset;

    // Maybe we need to work from the other end.
    if (TD->isLittleEndian()) Offset = FieldSize - (Offset + Size);
    AddUInt(MemberDie, dwarf::DW_AT_bit_offset, 0, Offset);
  }

  DIEBlock *Block = new DIEBlock();
  AddUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);
  AddUInt(Block, 0, dwarf::DW_FORM_udata, DT.getOffsetInBits() >> 3);
  AddBlock(MemberDie, dwarf::DW_AT_data_member_location, 0, Block);

  if (DT.isProtected())
    AddUInt(MemberDie, dwarf::DW_AT_accessibility, 0,
            dwarf::DW_ACCESS_protected);
  else if (DT.isPrivate())
    AddUInt(MemberDie, dwarf::DW_AT_accessibility, 0,
            dwarf::DW_ACCESS_private);

  return MemberDie;
}

/// CreateSubprogramDIE - Create new DIE using SP.
DIE *DwarfDebug::CreateSubprogramDIE(CompileUnit *DW_Unit,
                                     const DISubprogram &SP,
                                     bool IsConstructor,
                                     bool IsInlined) {
  DIE *SPDie = new DIE(dwarf::DW_TAG_subprogram);

  std::string Name;
  SP.getName(Name);
  AddString(SPDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);

  std::string LinkageName;
  SP.getLinkageName(LinkageName);
  if (!LinkageName.empty()) {
    // Skip special LLVM prefix that is used to inform the asm printer to not emit
    // usual symbol prefix before the symbol name. This happens for Objective-C
    // symbol names and symbol whose name is replaced using GCC's __asm__ attribute.
    if (LinkageName[0] == 1)
      LinkageName = &LinkageName[1];
    AddString(SPDie, dwarf::DW_AT_MIPS_linkage_name, dwarf::DW_FORM_string,
              LinkageName);
  }
  AddSourceLine(SPDie, &SP);

  DICompositeType SPTy = SP.getType();
  DIArray Args = SPTy.getTypeArray();

  // Add prototyped tag, if C or ObjC.
  unsigned Lang = SP.getCompileUnit().getLanguage();
  if (Lang == dwarf::DW_LANG_C99 || Lang == dwarf::DW_LANG_C89 ||
      Lang == dwarf::DW_LANG_ObjC)
    AddUInt(SPDie, dwarf::DW_AT_prototyped, dwarf::DW_FORM_flag, 1);

  // Add Return Type.
  unsigned SPTag = SPTy.getTag();
  if (!IsConstructor) {
    if (Args.isNull() || SPTag != dwarf::DW_TAG_subroutine_type)
      AddType(DW_Unit, SPDie, SPTy);
    else
      AddType(DW_Unit, SPDie, DIType(Args.getElement(0).getGV()));
  }

  if (!SP.isDefinition()) {
    AddUInt(SPDie, dwarf::DW_AT_declaration, dwarf::DW_FORM_flag, 1);

    // Add arguments. Do not add arguments for subprogram definition. They will
    // be handled through RecordVariable.
    if (SPTag == dwarf::DW_TAG_subroutine_type)
      for (unsigned i = 1, N =  Args.getNumElements(); i < N; ++i) {
        DIE *Arg = new DIE(dwarf::DW_TAG_formal_parameter);
        AddType(DW_Unit, Arg, DIType(Args.getElement(i).getGV()));
        AddUInt(Arg, dwarf::DW_AT_artificial, dwarf::DW_FORM_flag, 1); // ??
        SPDie->AddChild(Arg);
      }
  }

  if (!SP.isLocalToUnit() && !IsInlined)
    AddUInt(SPDie, dwarf::DW_AT_external, dwarf::DW_FORM_flag, 1);

  // DW_TAG_inlined_subroutine may refer to this DIE.
  DIE *&Slot = DW_Unit->getDieMapSlotFor(SP.getGV());
  Slot = SPDie;
  return SPDie;
}

/// FindCompileUnit - Get the compile unit for the given descriptor.
///
CompileUnit &DwarfDebug::FindCompileUnit(DICompileUnit Unit) const {
  DenseMap<Value *, CompileUnit *>::const_iterator I =
    CompileUnitMap.find(Unit.getGV());
  assert(I != CompileUnitMap.end() && "Missing compile unit.");
  return *I->second;
}

/// CreateDbgScopeVariable - Create a new scope variable.
///
DIE *DwarfDebug::CreateDbgScopeVariable(DbgVariable *DV, CompileUnit *Unit) {
  // Get the descriptor.
  const DIVariable &VD = DV->getVariable();

  // Translate tag to proper Dwarf tag.  The result variable is dropped for
  // now.
  unsigned Tag;
  switch (VD.getTag()) {
  case dwarf::DW_TAG_return_variable:
    return NULL;
  case dwarf::DW_TAG_arg_variable:
    Tag = dwarf::DW_TAG_formal_parameter;
    break;
  case dwarf::DW_TAG_auto_variable:    // fall thru
  default:
    Tag = dwarf::DW_TAG_variable;
    break;
  }

  // Define variable debug information entry.
  DIE *VariableDie = new DIE(Tag);
  std::string Name;
  VD.getName(Name);
  AddString(VariableDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);

  // Add source line info if available.
  AddSourceLine(VariableDie, &VD);

  // Add variable type.
  AddType(Unit, VariableDie, VD.getType());

  // Add variable address.
  if (!DV->isInlinedFnVar()) {
    // Variables for abstract instances of inlined functions don't get a
    // location.
    MachineLocation Location;
    Location.set(RI->getFrameRegister(*MF),
                 RI->getFrameIndexOffset(*MF, DV->getFrameIndex()));
    AddAddress(VariableDie, dwarf::DW_AT_location, Location);
  }

  return VariableDie;
}

/// getOrCreateScope - Returns the scope associated with the given descriptor.
///
DbgScope *DwarfDebug::getOrCreateScope(GlobalVariable *V) {
  DbgScope *&Slot = DbgScopeMap[V];
  if (Slot) return Slot;

  DbgScope *Parent = NULL;
  DIBlock Block(V);

  // Don't create a new scope if we already created one for an inlined function.
  DenseMap<const GlobalVariable *, DbgScope *>::iterator
    II = AbstractInstanceRootMap.find(V);
  if (II != AbstractInstanceRootMap.end())
    return LexicalScopeStack.back();

  if (!Block.isNull()) {
    DIDescriptor ParentDesc = Block.getContext();
    Parent =
      ParentDesc.isNull() ?  NULL : getOrCreateScope(ParentDesc.getGV());
  }

  Slot = new DbgScope(Parent, DIDescriptor(V));

  if (Parent)
    Parent->AddScope(Slot);
  else
    // First function is top level function.
    FunctionDbgScope = Slot;

  return Slot;
}

/// ConstructDbgScope - Construct the components of a scope.
///
void DwarfDebug::ConstructDbgScope(DbgScope *ParentScope,
                                   unsigned ParentStartID,
                                   unsigned ParentEndID,
                                   DIE *ParentDie, CompileUnit *Unit) {
  // Add variables to scope.
  SmallVector<DbgVariable *, 8> &Variables = ParentScope->getVariables();
  for (unsigned i = 0, N = Variables.size(); i < N; ++i) {
    DIE *VariableDie = CreateDbgScopeVariable(Variables[i], Unit);
    if (VariableDie) ParentDie->AddChild(VariableDie);
  }

  // Add concrete instances to scope.
  SmallVector<DbgConcreteScope *, 8> &ConcreteInsts =
    ParentScope->getConcreteInsts();
  for (unsigned i = 0, N = ConcreteInsts.size(); i < N; ++i) {
    DbgConcreteScope *ConcreteInst = ConcreteInsts[i];
    DIE *Die = ConcreteInst->getDie();

    unsigned StartID = ConcreteInst->getStartLabelID();
    unsigned EndID = ConcreteInst->getEndLabelID();

    // Add the scope bounds.
    if (StartID)
      AddLabel(Die, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
               DWLabel("label", StartID));
    else
      AddLabel(Die, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
               DWLabel("func_begin", SubprogramCount));

    if (EndID)
      AddLabel(Die, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
               DWLabel("label", EndID));
    else
      AddLabel(Die, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
               DWLabel("func_end", SubprogramCount));

    ParentDie->AddChild(Die);
  }

  // Add nested scopes.
  SmallVector<DbgScope *, 4> &Scopes = ParentScope->getScopes();
  for (unsigned j = 0, M = Scopes.size(); j < M; ++j) {
    // Define the Scope debug information entry.
    DbgScope *Scope = Scopes[j];

    unsigned StartID = MMI->MappedLabel(Scope->getStartLabelID());
    unsigned EndID = MMI->MappedLabel(Scope->getEndLabelID());

    // Ignore empty scopes.
    if (StartID == EndID && StartID != 0) continue;

    // Do not ignore inlined scopes even if they don't have any variables or
    // scopes.
    if (Scope->getScopes().empty() && Scope->getVariables().empty() &&
        Scope->getConcreteInsts().empty())
      continue;

    if (StartID == ParentStartID && EndID == ParentEndID) {
      // Just add stuff to the parent scope.
      ConstructDbgScope(Scope, ParentStartID, ParentEndID, ParentDie, Unit);
    } else {
      DIE *ScopeDie = new DIE(dwarf::DW_TAG_lexical_block);

      // Add the scope bounds.
      if (StartID)
        AddLabel(ScopeDie, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
                 DWLabel("label", StartID));
      else
        AddLabel(ScopeDie, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
                 DWLabel("func_begin", SubprogramCount));

      if (EndID)
        AddLabel(ScopeDie, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
                 DWLabel("label", EndID));
      else
        AddLabel(ScopeDie, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
                 DWLabel("func_end", SubprogramCount));

      // Add the scope's contents.
      ConstructDbgScope(Scope, StartID, EndID, ScopeDie, Unit);
      ParentDie->AddChild(ScopeDie);
    }
  }
}

/// ConstructFunctionDbgScope - Construct the scope for the subprogram.
///
void DwarfDebug::ConstructFunctionDbgScope(DbgScope *RootScope,
                                           bool AbstractScope) {
  // Exit if there is no root scope.
  if (!RootScope) return;
  DIDescriptor Desc = RootScope->getDesc();
  if (Desc.isNull())
    return;

  // Get the subprogram debug information entry.
  DISubprogram SPD(Desc.getGV());

  // Get the subprogram die.
  DIE *SPDie = ModuleCU->getDieMapSlotFor(SPD.getGV());
  assert(SPDie && "Missing subprogram descriptor");

  if (!AbstractScope) {
    // Add the function bounds.
    AddLabel(SPDie, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
             DWLabel("func_begin", SubprogramCount));
    AddLabel(SPDie, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
             DWLabel("func_end", SubprogramCount));
    MachineLocation Location(RI->getFrameRegister(*MF));
    AddAddress(SPDie, dwarf::DW_AT_frame_base, Location);
  }

  ConstructDbgScope(RootScope, 0, 0, SPDie, ModuleCU);
}

/// ConstructDefaultDbgScope - Construct a default scope for the subprogram.
///
void DwarfDebug::ConstructDefaultDbgScope(MachineFunction *MF) {
  StringMap<DIE*> &Globals = ModuleCU->getGlobals();
  StringMap<DIE*>::iterator GI = Globals.find(MF->getFunction()->getName());
  if (GI != Globals.end()) {
    DIE *SPDie = GI->second;
    
    // Add the function bounds.
    AddLabel(SPDie, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
             DWLabel("func_begin", SubprogramCount));
    AddLabel(SPDie, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
             DWLabel("func_end", SubprogramCount));
    
    MachineLocation Location(RI->getFrameRegister(*MF));
    AddAddress(SPDie, dwarf::DW_AT_frame_base, Location);
  }
}

/// GetOrCreateSourceID - Look up the source id with the given directory and
/// source file names. If none currently exists, create a new id and insert it
/// in the SourceIds map. This can update DirectoryNames and SourceFileNames
/// maps as well.
unsigned DwarfDebug::GetOrCreateSourceID(const std::string &DirName,
                                         const std::string &FileName) {
  unsigned DId;
  StringMap<unsigned>::iterator DI = DirectoryIdMap.find(DirName);
  if (DI != DirectoryIdMap.end()) {
    DId = DI->getValue();
  } else {
    DId = DirectoryNames.size() + 1;
    DirectoryIdMap[DirName] = DId;
    DirectoryNames.push_back(DirName);
  }

  unsigned FId;
  StringMap<unsigned>::iterator FI = SourceFileIdMap.find(FileName);
  if (FI != SourceFileIdMap.end()) {
    FId = FI->getValue();
  } else {
    FId = SourceFileNames.size() + 1;
    SourceFileIdMap[FileName] = FId;
    SourceFileNames.push_back(FileName);
  }

  DenseMap<std::pair<unsigned, unsigned>, unsigned>::iterator SI =
    SourceIdMap.find(std::make_pair(DId, FId));
  if (SI != SourceIdMap.end())
    return SI->second;

  unsigned SrcId = SourceIds.size() + 1;  // DW_AT_decl_file cannot be 0.
  SourceIdMap[std::make_pair(DId, FId)] = SrcId;
  SourceIds.push_back(std::make_pair(DId, FId));

  return SrcId;
}

void DwarfDebug::ConstructCompileUnit(GlobalVariable *GV) {
  DICompileUnit DIUnit(GV);
  std::string Dir, FN, Prod;
  unsigned ID = GetOrCreateSourceID(DIUnit.getDirectory(Dir),
                                    DIUnit.getFilename(FN));

  DIE *Die = new DIE(dwarf::DW_TAG_compile_unit);
  AddSectionOffset(Die, dwarf::DW_AT_stmt_list, dwarf::DW_FORM_data4,
                   DWLabel("section_line", 0), DWLabel("section_line", 0),
                   false);
  AddString(Die, dwarf::DW_AT_producer, dwarf::DW_FORM_string,
            DIUnit.getProducer(Prod));
  AddUInt(Die, dwarf::DW_AT_language, dwarf::DW_FORM_data1,
          DIUnit.getLanguage());
  AddString(Die, dwarf::DW_AT_name, dwarf::DW_FORM_string, FN);

  if (!Dir.empty())
    AddString(Die, dwarf::DW_AT_comp_dir, dwarf::DW_FORM_string, Dir);
  if (DIUnit.isOptimized())
    AddUInt(Die, dwarf::DW_AT_APPLE_optimized, dwarf::DW_FORM_flag, 1);

  std::string Flags;
  DIUnit.getFlags(Flags);
  if (!Flags.empty())
    AddString(Die, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string, Flags);

  unsigned RVer = DIUnit.getRunTimeVersion();
  if (RVer)
    AddUInt(Die, dwarf::DW_AT_APPLE_major_runtime_vers,
            dwarf::DW_FORM_data1, RVer);

  CompileUnit *Unit = new CompileUnit(ID, Die);
  if (!ModuleCU && DIUnit.isMain()) {
    // Use first compile unit marked as isMain as the compile unit
    // for this module.
    ModuleCU = Unit;
  }

  CompileUnitMap[DIUnit.getGV()] = Unit;
  CompileUnits.push_back(Unit);
}

void DwarfDebug::ConstructGlobalVariableDIE(GlobalVariable *GV) {
  DIGlobalVariable DI_GV(GV);

  // Check for pre-existence.
  DIE *&Slot = ModuleCU->getDieMapSlotFor(DI_GV.getGV());
  if (Slot)
    return;

  DIE *VariableDie = CreateGlobalVariableDIE(ModuleCU, DI_GV);

  // Add address.
  DIEBlock *Block = new DIEBlock();
  AddUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_addr);
  std::string GLN;
  AddObjectLabel(Block, 0, dwarf::DW_FORM_udata,
                 Asm->getGlobalLinkName(DI_GV.getGlobal(), GLN));
  AddBlock(VariableDie, dwarf::DW_AT_location, 0, Block);

  // Add to map.
  Slot = VariableDie;

  // Add to context owner.
  ModuleCU->getDie()->AddChild(VariableDie);

  // Expose as global. FIXME - need to check external flag.
  std::string Name;
  ModuleCU->AddGlobal(DI_GV.getName(Name), VariableDie);
  return;
}

void DwarfDebug::ConstructSubprogram(GlobalVariable *GV) {
  DISubprogram SP(GV);

  // Check for pre-existence.
  DIE *&Slot = ModuleCU->getDieMapSlotFor(GV);
  if (Slot)
    return;

  if (!SP.isDefinition())
    // This is a method declaration which will be handled while constructing
    // class type.
    return;

  DIE *SubprogramDie = CreateSubprogramDIE(ModuleCU, SP);

  // Add to map.
  Slot = SubprogramDie;

  // Add to context owner.
  ModuleCU->getDie()->AddChild(SubprogramDie);

  // Expose as global.
  std::string Name;
  ModuleCU->AddGlobal(SP.getName(Name), SubprogramDie);
  return;
}

  /// BeginModule - Emit all Dwarf sections that should come prior to the
  /// content. Create global DIEs and emit initial debug info sections.
  /// This is inovked by the target AsmPrinter.
void DwarfDebug::BeginModule(Module *M, MachineModuleInfo *mmi) {
  this->M = M;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  DebugInfoFinder DbgFinder;
  DbgFinder.processModule(*M);

  // Create all the compile unit DIEs.
  for (DebugInfoFinder::iterator I = DbgFinder.compile_unit_begin(),
         E = DbgFinder.compile_unit_end(); I != E; ++I)
    ConstructCompileUnit(*I);

  if (CompileUnits.empty()) {
    if (TimePassesIsEnabled)
      DebugTimer->stopTimer();

    return;
  }

  // If main compile unit for this module is not seen than randomly
  // select first compile unit.
  if (!ModuleCU)
    ModuleCU = CompileUnits[0];

  // If there is not any debug info available for any global variables and any
  // subprograms then there is not any debug info to emit.
  if (DbgFinder.global_variable_count() == 0
      && DbgFinder.subprogram_count() == 0) {
    if (TimePassesIsEnabled)
      DebugTimer->stopTimer();
    return;
  }
  
  // Create DIEs for each of the externally visible global variables.
  for (DebugInfoFinder::iterator I = DbgFinder.global_variable_begin(),
         E = DbgFinder.global_variable_end(); I != E; ++I)
    ConstructGlobalVariableDIE(*I);

  // Create DIEs for each of the externally visible subprograms.
  for (DebugInfoFinder::iterator I = DbgFinder.subprogram_begin(),
         E = DbgFinder.subprogram_end(); I != E; ++I)
    ConstructSubprogram(*I);

  MMI = mmi;
  shouldEmit = true;
  MMI->setDebugInfoAvailability(true);

  // Prime section data.
  SectionMap.insert(Asm->getObjFileLowering().getTextSection());

  // Print out .file directives to specify files for .loc directives. These are
  // printed out early so that they precede any .loc directives.
  if (TAI->hasDotLocAndDotFile()) {
    for (unsigned i = 1, e = getNumSourceIds()+1; i != e; ++i) {
      // Remember source id starts at 1.
      std::pair<unsigned, unsigned> Id = getSourceDirectoryAndFileIds(i);
      sys::Path FullPath(getSourceDirectoryName(Id.first));
      bool AppendOk =
        FullPath.appendComponent(getSourceFileName(Id.second));
      assert(AppendOk && "Could not append filename to directory!");
      AppendOk = false;
      Asm->EmitFile(i, FullPath.toString());
      Asm->EOL();
    }
  }

  // Emit initial sections
  EmitInitial();

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

/// EndModule - Emit all Dwarf sections that should come after the content.
///
void DwarfDebug::EndModule() {
  if (!ShouldEmitDwarfDebug())
    return;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  // Standard sections final addresses.
  Asm->SwitchToSection(Asm->getObjFileLowering().getTextSection());
  EmitLabel("text_end", 0);
  Asm->SwitchToSection(Asm->getObjFileLowering().getDataSection());
  EmitLabel("data_end", 0);

  // End text sections.
  for (unsigned i = 1, N = SectionMap.size(); i <= N; ++i) {
    Asm->SwitchToSection(SectionMap[i]);
    EmitLabel("section_end", i);
  }

  // Emit common frame information.
  EmitCommonDebugFrame();

  // Emit function debug frame information
  for (std::vector<FunctionDebugFrameInfo>::iterator I = DebugFrames.begin(),
         E = DebugFrames.end(); I != E; ++I)
    EmitFunctionDebugFrame(*I);

  // Compute DIE offsets and sizes.
  SizeAndOffsets();

  // Emit all the DIEs into a debug info section
  EmitDebugInfo();

  // Corresponding abbreviations into a abbrev section.
  EmitAbbreviations();

  // Emit source line correspondence into a debug line section.
  EmitDebugLines();

  // Emit info into a debug pubnames section.
  EmitDebugPubNames();

  // Emit info into a debug str section.
  EmitDebugStr();

  // Emit info into a debug loc section.
  EmitDebugLoc();

  // Emit info into a debug aranges section.
  EmitDebugARanges();

  // Emit info into a debug ranges section.
  EmitDebugRanges();

  // Emit info into a debug macinfo section.
  EmitDebugMacInfo();

  // Emit inline info.
  EmitDebugInlineInfo();

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

/// BeginFunction - Gather pre-function debug information.  Assumes being
/// emitted immediately after the function entry point.
void DwarfDebug::BeginFunction(MachineFunction *MF) {
  this->MF = MF;

  if (!ShouldEmitDwarfDebug()) return;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  // Begin accumulating function debug information.
  MMI->BeginFunction(MF);

  // Assumes in correct section after the entry point.
  EmitLabel("func_begin", ++SubprogramCount);

  // Emit label for the implicitly defined dbg.stoppoint at the start of the
  // function.
  DebugLoc FDL = MF->getDefaultDebugLoc();
  if (!FDL.isUnknown()) {
    DebugLocTuple DLT = MF->getDebugLocTuple(FDL);
    unsigned LabelID = RecordSourceLine(DLT.Line, DLT.Col,
                                        DICompileUnit(DLT.CompileUnit));
    Asm->printLabel(LabelID);
  }

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

/// EndFunction - Gather and emit post-function debug information.
///
void DwarfDebug::EndFunction(MachineFunction *MF) {
  if (!ShouldEmitDwarfDebug()) return;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  // Define end label for subprogram.
  EmitLabel("func_end", SubprogramCount);

  // Get function line info.
  if (!Lines.empty()) {
    // Get section line info.
    unsigned ID = SectionMap.insert(Asm->CurrentSection_);
    if (SectionSourceLines.size() < ID) SectionSourceLines.resize(ID);
    std::vector<SrcLineInfo> &SectionLineInfos = SectionSourceLines[ID-1];
    // Append the function info to section info.
    SectionLineInfos.insert(SectionLineInfos.end(),
                            Lines.begin(), Lines.end());
  }

  // Construct the DbgScope for abstract instances.
  for (SmallVector<DbgScope *, 32>::iterator
         I = AbstractInstanceRootList.begin(),
         E = AbstractInstanceRootList.end(); I != E; ++I)
    ConstructFunctionDbgScope(*I);

  // Construct scopes for subprogram.
  if (FunctionDbgScope)
    ConstructFunctionDbgScope(FunctionDbgScope);
  else
    // FIXME: This is wrong. We are essentially getting past a problem with
    // debug information not being able to handle unreachable blocks that have
    // debug information in them. In particular, those unreachable blocks that
    // have "region end" info in them. That situation results in the "root
    // scope" not being created. If that's the case, then emit a "default"
    // scope, i.e., one that encompasses the whole function. This isn't
    // desirable. And a better way of handling this (and all of the debugging
    // information) needs to be explored.
    ConstructDefaultDbgScope(MF);

  DebugFrames.push_back(FunctionDebugFrameInfo(SubprogramCount,
                                               MMI->getFrameMoves()));

  // Clear debug info
  if (FunctionDbgScope) {
    delete FunctionDbgScope;
    DbgScopeMap.clear();
    DbgAbstractScopeMap.clear();
    DbgConcreteScopeMap.clear();
    InlinedVariableScopes.clear();
    FunctionDbgScope = NULL;
    LexicalScopeStack.clear();
    AbstractInstanceRootList.clear();
    AbstractInstanceRootMap.clear();
  }

  Lines.clear();

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

/// RecordSourceLine - Records location information and associates it with a
/// label. Returns a unique label ID used to generate a label and provide
/// correspondence to the source line list.
unsigned DwarfDebug::RecordSourceLine(Value *V, unsigned Line, unsigned Col) {
  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  CompileUnit *Unit = CompileUnitMap[V];
  assert(Unit && "Unable to find CompileUnit");
  unsigned ID = MMI->NextLabelID();
  Lines.push_back(SrcLineInfo(Line, Col, Unit->getID(), ID));

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return ID;
}

/// RecordSourceLine - Records location information and associates it with a
/// label. Returns a unique label ID used to generate a label and provide
/// correspondence to the source line list.
unsigned DwarfDebug::RecordSourceLine(unsigned Line, unsigned Col,
                                      DICompileUnit CU) {
  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  std::string Dir, Fn;
  unsigned Src = GetOrCreateSourceID(CU.getDirectory(Dir),
                                     CU.getFilename(Fn));
  unsigned ID = MMI->NextLabelID();
  Lines.push_back(SrcLineInfo(Line, Col, Src, ID));

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return ID;
}

/// getOrCreateSourceID - Public version of GetOrCreateSourceID. This can be
/// timed. Look up the source id with the given directory and source file
/// names. If none currently exists, create a new id and insert it in the
/// SourceIds map. This can update DirectoryNames and SourceFileNames maps as
/// well.
unsigned DwarfDebug::getOrCreateSourceID(const std::string &DirName,
                                         const std::string &FileName) {
  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  unsigned SrcId = GetOrCreateSourceID(DirName, FileName);

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return SrcId;
}

/// RecordRegionStart - Indicate the start of a region.
unsigned DwarfDebug::RecordRegionStart(GlobalVariable *V) {
  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  DbgScope *Scope = getOrCreateScope(V);
  unsigned ID = MMI->NextLabelID();
  if (!Scope->getStartLabelID()) Scope->setStartLabelID(ID);
  LexicalScopeStack.push_back(Scope);

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return ID;
}

/// RecordRegionEnd - Indicate the end of a region.
unsigned DwarfDebug::RecordRegionEnd(GlobalVariable *V) {
  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  DbgScope *Scope = getOrCreateScope(V);
  unsigned ID = MMI->NextLabelID();
  Scope->setEndLabelID(ID);
  // FIXME : region.end() may not be in the last basic block.
  // For now, do not pop last lexical scope because next basic
  // block may start new inlined function's body.
  unsigned LSSize = LexicalScopeStack.size();
  if (LSSize != 0 && LSSize != 1)
    LexicalScopeStack.pop_back();

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return ID;
}

/// RecordVariable - Indicate the declaration of a local variable.
void DwarfDebug::RecordVariable(GlobalVariable *GV, unsigned FrameIndex,
                                const MachineInstr *MI) {
  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  DIDescriptor Desc(GV);
  DbgScope *Scope = NULL;
  bool InlinedFnVar = false;

  if (Desc.getTag() == dwarf::DW_TAG_variable) {
    // GV is a global variable.
    DIGlobalVariable DG(GV);
    Scope = getOrCreateScope(DG.getContext().getGV());
  } else {
    DenseMap<const MachineInstr *, DbgScope *>::iterator
      SI = InlinedVariableScopes.find(MI);

    if (SI != InlinedVariableScopes.end()) {
      // or GV is an inlined local variable.
      Scope = SI->second;
      InlinedFnVar = true;
    } else {
      DIVariable DV(GV);
      GlobalVariable *V = DV.getContext().getGV();

      // or GV is a local variable.
      Scope = getOrCreateScope(V);
    }
  }

  assert(Scope && "Unable to find the variable's scope");
  DbgVariable *DV = new DbgVariable(DIVariable(GV), FrameIndex, InlinedFnVar);
  Scope->AddVariable(DV);

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

//// RecordInlinedFnStart - Indicate the start of inlined subroutine.
unsigned DwarfDebug::RecordInlinedFnStart(DISubprogram &SP, DICompileUnit CU,
                                          unsigned Line, unsigned Col) {
  unsigned LabelID = MMI->NextLabelID();

  if (!TAI->doesDwarfUsesInlineInfoSection())
    return LabelID;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  GlobalVariable *GV = SP.getGV();
  DenseMap<const GlobalVariable *, DbgScope *>::iterator
    II = AbstractInstanceRootMap.find(GV);

  if (II == AbstractInstanceRootMap.end()) {
    // Create an abstract instance entry for this inlined function if it doesn't
    // already exist.
    DbgScope *Scope = new DbgScope(NULL, DIDescriptor(GV));

    // Get the compile unit context.
    DIE *SPDie = ModuleCU->getDieMapSlotFor(GV);
    if (!SPDie)
      SPDie = CreateSubprogramDIE(ModuleCU, SP, false, true);

    // Mark as being inlined. This makes this subprogram entry an abstract
    // instance root.
    // FIXME: Our debugger doesn't care about the value of DW_AT_inline, only
    // that it's defined. That probably won't change in the future. However,
    // this could be more elegant.
    AddUInt(SPDie, dwarf::DW_AT_inline, 0, dwarf::DW_INL_declared_not_inlined);

    // Keep track of the abstract scope for this function.
    DbgAbstractScopeMap[GV] = Scope;

    AbstractInstanceRootMap[GV] = Scope;
    AbstractInstanceRootList.push_back(Scope);
  }

  // Create a concrete inlined instance for this inlined function.
  DbgConcreteScope *ConcreteScope = new DbgConcreteScope(DIDescriptor(GV));
  DIE *ScopeDie = new DIE(dwarf::DW_TAG_inlined_subroutine);
  ScopeDie->setAbstractCompileUnit(ModuleCU);

  DIE *Origin = ModuleCU->getDieMapSlotFor(GV);
  AddDIEEntry(ScopeDie, dwarf::DW_AT_abstract_origin,
              dwarf::DW_FORM_ref4, Origin);
  AddUInt(ScopeDie, dwarf::DW_AT_call_file, 0, ModuleCU->getID());
  AddUInt(ScopeDie, dwarf::DW_AT_call_line, 0, Line);
  AddUInt(ScopeDie, dwarf::DW_AT_call_column, 0, Col);

  ConcreteScope->setDie(ScopeDie);
  ConcreteScope->setStartLabelID(LabelID);
  MMI->RecordUsedDbgLabel(LabelID);

  LexicalScopeStack.back()->AddConcreteInst(ConcreteScope);

  // Keep track of the concrete scope that's inlined into this function.
  DenseMap<GlobalVariable *, SmallVector<DbgScope *, 8> >::iterator
    SI = DbgConcreteScopeMap.find(GV);

  if (SI == DbgConcreteScopeMap.end())
    DbgConcreteScopeMap[GV].push_back(ConcreteScope);
  else
    SI->second.push_back(ConcreteScope);

  // Track the start label for this inlined function.
  DenseMap<GlobalVariable *, SmallVector<unsigned, 4> >::iterator
    I = InlineInfo.find(GV);

  if (I == InlineInfo.end())
    InlineInfo[GV].push_back(LabelID);
  else
    I->second.push_back(LabelID);

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return LabelID;
}

/// RecordInlinedFnEnd - Indicate the end of inlined subroutine.
unsigned DwarfDebug::RecordInlinedFnEnd(DISubprogram &SP) {
  if (!TAI->doesDwarfUsesInlineInfoSection())
    return 0;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  GlobalVariable *GV = SP.getGV();
  DenseMap<GlobalVariable *, SmallVector<DbgScope *, 8> >::iterator
    I = DbgConcreteScopeMap.find(GV);

  if (I == DbgConcreteScopeMap.end()) {
    // FIXME: Can this situation actually happen? And if so, should it?
    if (TimePassesIsEnabled)
      DebugTimer->stopTimer();

    return 0;
  }

  SmallVector<DbgScope *, 8> &Scopes = I->second;
  if (Scopes.empty()) {
    // Returned ID is 0 if this is unbalanced "end of inlined
    // scope". This could happen if optimizer eats dbg intrinsics
    // or "beginning of inlined scope" is not recoginized due to
    // missing location info. In such cases, ignore this region.end.
    return 0;
  }

  DbgScope *Scope = Scopes.back(); Scopes.pop_back();
  unsigned ID = MMI->NextLabelID();
  MMI->RecordUsedDbgLabel(ID);
  Scope->setEndLabelID(ID);

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return ID;
}

/// RecordVariableScope - Record scope for the variable declared by
/// DeclareMI. DeclareMI must describe TargetInstrInfo::DECLARE. Record scopes
/// for only inlined subroutine variables. Other variables's scopes are
/// determined during RecordVariable().
void DwarfDebug::RecordVariableScope(DIVariable &DV,
                                     const MachineInstr *DeclareMI) {
  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  DISubprogram SP(DV.getContext().getGV());

  if (SP.isNull()) {
    if (TimePassesIsEnabled)
      DebugTimer->stopTimer();

    return;
  }

  DenseMap<GlobalVariable *, DbgScope *>::iterator
    I = DbgAbstractScopeMap.find(SP.getGV());
  if (I != DbgAbstractScopeMap.end())
    InlinedVariableScopes[DeclareMI] = I->second;

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

//===----------------------------------------------------------------------===//
// Emit Methods
//===----------------------------------------------------------------------===//

/// SizeAndOffsetDie - Compute the size and offset of a DIE.
///
unsigned DwarfDebug::SizeAndOffsetDie(DIE *Die, unsigned Offset, bool Last) {
  // Get the children.
  const std::vector<DIE *> &Children = Die->getChildren();

  // If not last sibling and has children then add sibling offset attribute.
  if (!Last && !Children.empty()) Die->AddSiblingOffset();

  // Record the abbreviation.
  AssignAbbrevNumber(Die->getAbbrev());

  // Get the abbreviation for this DIE.
  unsigned AbbrevNumber = Die->getAbbrevNumber();
  const DIEAbbrev *Abbrev = Abbreviations[AbbrevNumber - 1];

  // Set DIE offset
  Die->setOffset(Offset);

  // Start the size with the size of abbreviation code.
  Offset += TargetAsmInfo::getULEB128Size(AbbrevNumber);

  const SmallVector<DIEValue*, 32> &Values = Die->getValues();
  const SmallVector<DIEAbbrevData, 8> &AbbrevData = Abbrev->getData();

  // Size the DIE attribute values.
  for (unsigned i = 0, N = Values.size(); i < N; ++i)
    // Size attribute value.
    Offset += Values[i]->SizeOf(TD, AbbrevData[i].getForm());

  // Size the DIE children if any.
  if (!Children.empty()) {
    assert(Abbrev->getChildrenFlag() == dwarf::DW_CHILDREN_yes &&
           "Children flag not set");

    for (unsigned j = 0, M = Children.size(); j < M; ++j)
      Offset = SizeAndOffsetDie(Children[j], Offset, (j + 1) == M);

    // End of children marker.
    Offset += sizeof(int8_t);
  }

  Die->setSize(Offset - Die->getOffset());
  return Offset;
}

/// SizeAndOffsets - Compute the size and offset of all the DIEs.
///
void DwarfDebug::SizeAndOffsets() {
  // Compute size of compile unit header.
  static unsigned Offset =
    sizeof(int32_t) + // Length of Compilation Unit Info
    sizeof(int16_t) + // DWARF version number
    sizeof(int32_t) + // Offset Into Abbrev. Section
    sizeof(int8_t);   // Pointer Size (in bytes)

  SizeAndOffsetDie(ModuleCU->getDie(), Offset, true);
  CompileUnitOffsets[ModuleCU] = 0;
}

/// EmitInitial - Emit initial Dwarf declarations.  This is necessary for cc
/// tools to recognize the object file contains Dwarf information.
void DwarfDebug::EmitInitial() {
  // Check to see if we already emitted intial headers.
  if (didInitial) return;
  didInitial = true;

  // Dwarf sections base addresses.
  if (TAI->doesDwarfRequireFrameSection()) {
    Asm->SwitchToDataSection(TAI->getDwarfFrameSection());
    EmitLabel("section_debug_frame", 0);
  }

  Asm->SwitchToDataSection(TAI->getDwarfInfoSection());
  EmitLabel("section_info", 0);
  Asm->SwitchToDataSection(TAI->getDwarfAbbrevSection());
  EmitLabel("section_abbrev", 0);
  Asm->SwitchToDataSection(TAI->getDwarfARangesSection());
  EmitLabel("section_aranges", 0);

  if (const char *LineInfoDirective = TAI->getDwarfMacroInfoSection()) {
    Asm->SwitchToDataSection(LineInfoDirective);
    EmitLabel("section_macinfo", 0);
  }

  Asm->SwitchToDataSection(TAI->getDwarfLineSection());
  EmitLabel("section_line", 0);
  Asm->SwitchToDataSection(TAI->getDwarfLocSection());
  EmitLabel("section_loc", 0);
  Asm->SwitchToDataSection(TAI->getDwarfPubNamesSection());
  EmitLabel("section_pubnames", 0);
  Asm->SwitchToDataSection(TAI->getDwarfStrSection());
  EmitLabel("section_str", 0);
  Asm->SwitchToDataSection(TAI->getDwarfRangesSection());
  EmitLabel("section_ranges", 0);

  Asm->SwitchToSection(Asm->getObjFileLowering().getTextSection());
  EmitLabel("text_begin", 0);
  Asm->SwitchToSection(Asm->getObjFileLowering().getDataSection());
  EmitLabel("data_begin", 0);
}

/// EmitDIE - Recusively Emits a debug information entry.
///
void DwarfDebug::EmitDIE(DIE *Die) {
  // Get the abbreviation for this DIE.
  unsigned AbbrevNumber = Die->getAbbrevNumber();
  const DIEAbbrev *Abbrev = Abbreviations[AbbrevNumber - 1];

  Asm->EOL();

  // Emit the code (index) for the abbreviation.
  Asm->EmitULEB128Bytes(AbbrevNumber);

  if (Asm->isVerbose())
    Asm->EOL(std::string("Abbrev [" +
                         utostr(AbbrevNumber) +
                         "] 0x" + utohexstr(Die->getOffset()) +
                         ":0x" + utohexstr(Die->getSize()) + " " +
                         dwarf::TagString(Abbrev->getTag())));
  else
    Asm->EOL();

  SmallVector<DIEValue*, 32> &Values = Die->getValues();
  const SmallVector<DIEAbbrevData, 8> &AbbrevData = Abbrev->getData();

  // Emit the DIE attribute values.
  for (unsigned i = 0, N = Values.size(); i < N; ++i) {
    unsigned Attr = AbbrevData[i].getAttribute();
    unsigned Form = AbbrevData[i].getForm();
    assert(Form && "Too many attributes for DIE (check abbreviation)");

    switch (Attr) {
    case dwarf::DW_AT_sibling:
      Asm->EmitInt32(Die->SiblingOffset());
      break;
    case dwarf::DW_AT_abstract_origin: {
      DIEEntry *E = cast<DIEEntry>(Values[i]);
      DIE *Origin = E->getEntry();
      unsigned Addr =
        CompileUnitOffsets[Die->getAbstractCompileUnit()] +
        Origin->getOffset();

      Asm->EmitInt32(Addr);
      break;
    }
    default:
      // Emit an attribute using the defined form.
      Values[i]->EmitValue(this, Form);
      break;
    }

    Asm->EOL(dwarf::AttributeString(Attr));
  }

  // Emit the DIE children if any.
  if (Abbrev->getChildrenFlag() == dwarf::DW_CHILDREN_yes) {
    const std::vector<DIE *> &Children = Die->getChildren();

    for (unsigned j = 0, M = Children.size(); j < M; ++j)
      EmitDIE(Children[j]);

    Asm->EmitInt8(0); Asm->EOL("End Of Children Mark");
  }
}

/// EmitDebugInfo / EmitDebugInfoPerCU - Emit the debug info section.
///
void DwarfDebug::EmitDebugInfoPerCU(CompileUnit *Unit) {
  DIE *Die = Unit->getDie();

  // Emit the compile units header.
  EmitLabel("info_begin", Unit->getID());

  // Emit size of content not including length itself
  unsigned ContentSize = Die->getSize() +
    sizeof(int16_t) + // DWARF version number
    sizeof(int32_t) + // Offset Into Abbrev. Section
    sizeof(int8_t) +  // Pointer Size (in bytes)
    sizeof(int32_t);  // FIXME - extra pad for gdb bug.

  Asm->EmitInt32(ContentSize);  Asm->EOL("Length of Compilation Unit Info");
  Asm->EmitInt16(dwarf::DWARF_VERSION); Asm->EOL("DWARF version number");
  EmitSectionOffset("abbrev_begin", "section_abbrev", 0, 0, true, false);
  Asm->EOL("Offset Into Abbrev. Section");
  Asm->EmitInt8(TD->getPointerSize()); Asm->EOL("Address Size (in bytes)");

  EmitDIE(Die);
  // FIXME - extra padding for gdb bug.
  Asm->EmitInt8(0); Asm->EOL("Extra Pad For GDB");
  Asm->EmitInt8(0); Asm->EOL("Extra Pad For GDB");
  Asm->EmitInt8(0); Asm->EOL("Extra Pad For GDB");
  Asm->EmitInt8(0); Asm->EOL("Extra Pad For GDB");
  EmitLabel("info_end", Unit->getID());

  Asm->EOL();
}

void DwarfDebug::EmitDebugInfo() {
  // Start debug info section.
  Asm->SwitchToDataSection(TAI->getDwarfInfoSection());

  EmitDebugInfoPerCU(ModuleCU);
}

/// EmitAbbreviations - Emit the abbreviation section.
///
void DwarfDebug::EmitAbbreviations() const {
  // Check to see if it is worth the effort.
  if (!Abbreviations.empty()) {
    // Start the debug abbrev section.
    Asm->SwitchToDataSection(TAI->getDwarfAbbrevSection());

    EmitLabel("abbrev_begin", 0);

    // For each abbrevation.
    for (unsigned i = 0, N = Abbreviations.size(); i < N; ++i) {
      // Get abbreviation data
      const DIEAbbrev *Abbrev = Abbreviations[i];

      // Emit the abbrevations code (base 1 index.)
      Asm->EmitULEB128Bytes(Abbrev->getNumber());
      Asm->EOL("Abbreviation Code");

      // Emit the abbreviations data.
      Abbrev->Emit(Asm);

      Asm->EOL();
    }

    // Mark end of abbreviations.
    Asm->EmitULEB128Bytes(0); Asm->EOL("EOM(3)");

    EmitLabel("abbrev_end", 0);
    Asm->EOL();
  }
}

/// EmitEndOfLineMatrix - Emit the last address of the section and the end of
/// the line matrix.
///
void DwarfDebug::EmitEndOfLineMatrix(unsigned SectionEnd) {
  // Define last address of section.
  Asm->EmitInt8(0); Asm->EOL("Extended Op");
  Asm->EmitInt8(TD->getPointerSize() + 1); Asm->EOL("Op size");
  Asm->EmitInt8(dwarf::DW_LNE_set_address); Asm->EOL("DW_LNE_set_address");
  EmitReference("section_end", SectionEnd); Asm->EOL("Section end label");

  // Mark end of matrix.
  Asm->EmitInt8(0); Asm->EOL("DW_LNE_end_sequence");
  Asm->EmitULEB128Bytes(1); Asm->EOL();
  Asm->EmitInt8(1); Asm->EOL();
}

/// EmitDebugLines - Emit source line information.
///
void DwarfDebug::EmitDebugLines() {
  // If the target is using .loc/.file, the assembler will be emitting the
  // .debug_line table automatically.
  if (TAI->hasDotLocAndDotFile())
    return;

  // Minimum line delta, thus ranging from -10..(255-10).
  const int MinLineDelta = -(dwarf::DW_LNS_fixed_advance_pc + 1);
  // Maximum line delta, thus ranging from -10..(255-10).
  const int MaxLineDelta = 255 + MinLineDelta;

  // Start the dwarf line section.
  Asm->SwitchToDataSection(TAI->getDwarfLineSection());

  // Construct the section header.
  EmitDifference("line_end", 0, "line_begin", 0, true);
  Asm->EOL("Length of Source Line Info");
  EmitLabel("line_begin", 0);

  Asm->EmitInt16(dwarf::DWARF_VERSION); Asm->EOL("DWARF version number");

  EmitDifference("line_prolog_end", 0, "line_prolog_begin", 0, true);
  Asm->EOL("Prolog Length");
  EmitLabel("line_prolog_begin", 0);

  Asm->EmitInt8(1); Asm->EOL("Minimum Instruction Length");

  Asm->EmitInt8(1); Asm->EOL("Default is_stmt_start flag");

  Asm->EmitInt8(MinLineDelta); Asm->EOL("Line Base Value (Special Opcodes)");

  Asm->EmitInt8(MaxLineDelta); Asm->EOL("Line Range Value (Special Opcodes)");

  Asm->EmitInt8(-MinLineDelta); Asm->EOL("Special Opcode Base");

  // Line number standard opcode encodings argument count
  Asm->EmitInt8(0); Asm->EOL("DW_LNS_copy arg count");
  Asm->EmitInt8(1); Asm->EOL("DW_LNS_advance_pc arg count");
  Asm->EmitInt8(1); Asm->EOL("DW_LNS_advance_line arg count");
  Asm->EmitInt8(1); Asm->EOL("DW_LNS_set_file arg count");
  Asm->EmitInt8(1); Asm->EOL("DW_LNS_set_column arg count");
  Asm->EmitInt8(0); Asm->EOL("DW_LNS_negate_stmt arg count");
  Asm->EmitInt8(0); Asm->EOL("DW_LNS_set_basic_block arg count");
  Asm->EmitInt8(0); Asm->EOL("DW_LNS_const_add_pc arg count");
  Asm->EmitInt8(1); Asm->EOL("DW_LNS_fixed_advance_pc arg count");

  // Emit directories.
  for (unsigned DI = 1, DE = getNumSourceDirectories()+1; DI != DE; ++DI) {
    Asm->EmitString(getSourceDirectoryName(DI));
    Asm->EOL("Directory");
  }

  Asm->EmitInt8(0); Asm->EOL("End of directories");

  // Emit files.
  for (unsigned SI = 1, SE = getNumSourceIds()+1; SI != SE; ++SI) {
    // Remember source id starts at 1.
    std::pair<unsigned, unsigned> Id = getSourceDirectoryAndFileIds(SI);
    Asm->EmitString(getSourceFileName(Id.second));
    Asm->EOL("Source");
    Asm->EmitULEB128Bytes(Id.first);
    Asm->EOL("Directory #");
    Asm->EmitULEB128Bytes(0);
    Asm->EOL("Mod date");
    Asm->EmitULEB128Bytes(0);
    Asm->EOL("File size");
  }

  Asm->EmitInt8(0); Asm->EOL("End of files");

  EmitLabel("line_prolog_end", 0);

  // A sequence for each text section.
  unsigned SecSrcLinesSize = SectionSourceLines.size();

  for (unsigned j = 0; j < SecSrcLinesSize; ++j) {
    // Isolate current sections line info.
    const std::vector<SrcLineInfo> &LineInfos = SectionSourceLines[j];

    if (Asm->isVerbose()) {
      const MCSection *S = SectionMap[j + 1];
      O << '\t' << TAI->getCommentString() << " Section"
        << S->getName() << '\n';
    } else {
      Asm->EOL();
    }

    // Dwarf assumes we start with first line of first source file.
    unsigned Source = 1;
    unsigned Line = 1;

    // Construct rows of the address, source, line, column matrix.
    for (unsigned i = 0, N = LineInfos.size(); i < N; ++i) {
      const SrcLineInfo &LineInfo = LineInfos[i];
      unsigned LabelID = MMI->MappedLabel(LineInfo.getLabelID());
      if (!LabelID) continue;

      if (!Asm->isVerbose())
        Asm->EOL();
      else {
        std::pair<unsigned, unsigned> SourceID =
          getSourceDirectoryAndFileIds(LineInfo.getSourceID());
        O << '\t' << TAI->getCommentString() << ' '
          << getSourceDirectoryName(SourceID.first) << ' '
          << getSourceFileName(SourceID.second)
          <<" :" << utostr_32(LineInfo.getLine()) << '\n';
      }

      // Define the line address.
      Asm->EmitInt8(0); Asm->EOL("Extended Op");
      Asm->EmitInt8(TD->getPointerSize() + 1); Asm->EOL("Op size");
      Asm->EmitInt8(dwarf::DW_LNE_set_address); Asm->EOL("DW_LNE_set_address");
      EmitReference("label",  LabelID); Asm->EOL("Location label");

      // If change of source, then switch to the new source.
      if (Source != LineInfo.getSourceID()) {
        Source = LineInfo.getSourceID();
        Asm->EmitInt8(dwarf::DW_LNS_set_file); Asm->EOL("DW_LNS_set_file");
        Asm->EmitULEB128Bytes(Source); Asm->EOL("New Source");
      }

      // If change of line.
      if (Line != LineInfo.getLine()) {
        // Determine offset.
        int Offset = LineInfo.getLine() - Line;
        int Delta = Offset - MinLineDelta;

        // Update line.
        Line = LineInfo.getLine();

        // If delta is small enough and in range...
        if (Delta >= 0 && Delta < (MaxLineDelta - 1)) {
          // ... then use fast opcode.
          Asm->EmitInt8(Delta - MinLineDelta); Asm->EOL("Line Delta");
        } else {
          // ... otherwise use long hand.
          Asm->EmitInt8(dwarf::DW_LNS_advance_line);
          Asm->EOL("DW_LNS_advance_line");
          Asm->EmitSLEB128Bytes(Offset); Asm->EOL("Line Offset");
          Asm->EmitInt8(dwarf::DW_LNS_copy); Asm->EOL("DW_LNS_copy");
        }
      } else {
        // Copy the previous row (different address or source)
        Asm->EmitInt8(dwarf::DW_LNS_copy); Asm->EOL("DW_LNS_copy");
      }
    }

    EmitEndOfLineMatrix(j + 1);
  }

  if (SecSrcLinesSize == 0)
    // Because we're emitting a debug_line section, we still need a line
    // table. The linker and friends expect it to exist. If there's nothing to
    // put into it, emit an empty table.
    EmitEndOfLineMatrix(1);

  EmitLabel("line_end", 0);
  Asm->EOL();
}

/// EmitCommonDebugFrame - Emit common frame info into a debug frame section.
///
void DwarfDebug::EmitCommonDebugFrame() {
  if (!TAI->doesDwarfRequireFrameSection())
    return;

  int stackGrowth =
    Asm->TM.getFrameInfo()->getStackGrowthDirection() ==
      TargetFrameInfo::StackGrowsUp ?
    TD->getPointerSize() : -TD->getPointerSize();

  // Start the dwarf frame section.
  Asm->SwitchToDataSection(TAI->getDwarfFrameSection());

  EmitLabel("debug_frame_common", 0);
  EmitDifference("debug_frame_common_end", 0,
                 "debug_frame_common_begin", 0, true);
  Asm->EOL("Length of Common Information Entry");

  EmitLabel("debug_frame_common_begin", 0);
  Asm->EmitInt32((int)dwarf::DW_CIE_ID);
  Asm->EOL("CIE Identifier Tag");
  Asm->EmitInt8(dwarf::DW_CIE_VERSION);
  Asm->EOL("CIE Version");
  Asm->EmitString("");
  Asm->EOL("CIE Augmentation");
  Asm->EmitULEB128Bytes(1);
  Asm->EOL("CIE Code Alignment Factor");
  Asm->EmitSLEB128Bytes(stackGrowth);
  Asm->EOL("CIE Data Alignment Factor");
  Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), false));
  Asm->EOL("CIE RA Column");

  std::vector<MachineMove> Moves;
  RI->getInitialFrameState(Moves);

  EmitFrameMoves(NULL, 0, Moves, false);

  Asm->EmitAlignment(2, 0, 0, false);
  EmitLabel("debug_frame_common_end", 0);

  Asm->EOL();
}

/// EmitFunctionDebugFrame - Emit per function frame info into a debug frame
/// section.
void
DwarfDebug::EmitFunctionDebugFrame(const FunctionDebugFrameInfo&DebugFrameInfo){
  if (!TAI->doesDwarfRequireFrameSection())
    return;

  // Start the dwarf frame section.
  Asm->SwitchToDataSection(TAI->getDwarfFrameSection());

  EmitDifference("debug_frame_end", DebugFrameInfo.Number,
                 "debug_frame_begin", DebugFrameInfo.Number, true);
  Asm->EOL("Length of Frame Information Entry");

  EmitLabel("debug_frame_begin", DebugFrameInfo.Number);

  EmitSectionOffset("debug_frame_common", "section_debug_frame",
                    0, 0, true, false);
  Asm->EOL("FDE CIE offset");

  EmitReference("func_begin", DebugFrameInfo.Number);
  Asm->EOL("FDE initial location");
  EmitDifference("func_end", DebugFrameInfo.Number,
                 "func_begin", DebugFrameInfo.Number);
  Asm->EOL("FDE address range");

  EmitFrameMoves("func_begin", DebugFrameInfo.Number, DebugFrameInfo.Moves,
                 false);

  Asm->EmitAlignment(2, 0, 0, false);
  EmitLabel("debug_frame_end", DebugFrameInfo.Number);

  Asm->EOL();
}

void DwarfDebug::EmitDebugPubNamesPerCU(CompileUnit *Unit) {
  EmitDifference("pubnames_end", Unit->getID(),
                 "pubnames_begin", Unit->getID(), true);
  Asm->EOL("Length of Public Names Info");

  EmitLabel("pubnames_begin", Unit->getID());

  Asm->EmitInt16(dwarf::DWARF_VERSION); Asm->EOL("DWARF Version");

  EmitSectionOffset("info_begin", "section_info",
                    Unit->getID(), 0, true, false);
  Asm->EOL("Offset of Compilation Unit Info");

  EmitDifference("info_end", Unit->getID(), "info_begin", Unit->getID(),
                 true);
  Asm->EOL("Compilation Unit Length");

  StringMap<DIE*> &Globals = Unit->getGlobals();
  for (StringMap<DIE*>::const_iterator
         GI = Globals.begin(), GE = Globals.end(); GI != GE; ++GI) {
    const char *Name = GI->getKeyData();
    DIE * Entity = GI->second;

    Asm->EmitInt32(Entity->getOffset()); Asm->EOL("DIE offset");
    Asm->EmitString(Name, strlen(Name)); Asm->EOL("External Name");
  }

  Asm->EmitInt32(0); Asm->EOL("End Mark");
  EmitLabel("pubnames_end", Unit->getID());

  Asm->EOL();
}

/// EmitDebugPubNames - Emit visible names into a debug pubnames section.
///
void DwarfDebug::EmitDebugPubNames() {
  // Start the dwarf pubnames section.
  Asm->SwitchToDataSection(TAI->getDwarfPubNamesSection());

  EmitDebugPubNamesPerCU(ModuleCU);
}

/// EmitDebugStr - Emit visible names into a debug str section.
///
void DwarfDebug::EmitDebugStr() {
  // Check to see if it is worth the effort.
  if (!StringPool.empty()) {
    // Start the dwarf str section.
    Asm->SwitchToDataSection(TAI->getDwarfStrSection());

    // For each of strings in the string pool.
    for (unsigned StringID = 1, N = StringPool.size();
         StringID <= N; ++StringID) {
      // Emit a label for reference from debug information entries.
      EmitLabel("string", StringID);

      // Emit the string itself.
      const std::string &String = StringPool[StringID];
      Asm->EmitString(String); Asm->EOL();
    }

    Asm->EOL();
  }
}

/// EmitDebugLoc - Emit visible names into a debug loc section.
///
void DwarfDebug::EmitDebugLoc() {
  // Start the dwarf loc section.
  Asm->SwitchToDataSection(TAI->getDwarfLocSection());
  Asm->EOL();
}

/// EmitDebugARanges - Emit visible names into a debug aranges section.
///
void DwarfDebug::EmitDebugARanges() {
  // Start the dwarf aranges section.
  Asm->SwitchToDataSection(TAI->getDwarfARangesSection());

  // FIXME - Mock up
#if 0
  CompileUnit *Unit = GetBaseCompileUnit();

  // Don't include size of length
  Asm->EmitInt32(0x1c); Asm->EOL("Length of Address Ranges Info");

  Asm->EmitInt16(dwarf::DWARF_VERSION); Asm->EOL("Dwarf Version");

  EmitReference("info_begin", Unit->getID());
  Asm->EOL("Offset of Compilation Unit Info");

  Asm->EmitInt8(TD->getPointerSize()); Asm->EOL("Size of Address");

  Asm->EmitInt8(0); Asm->EOL("Size of Segment Descriptor");

  Asm->EmitInt16(0);  Asm->EOL("Pad (1)");
  Asm->EmitInt16(0);  Asm->EOL("Pad (2)");

  // Range 1
  EmitReference("text_begin", 0); Asm->EOL("Address");
  EmitDifference("text_end", 0, "text_begin", 0, true); Asm->EOL("Length");

  Asm->EmitInt32(0); Asm->EOL("EOM (1)");
  Asm->EmitInt32(0); Asm->EOL("EOM (2)");
#endif

  Asm->EOL();
}

/// EmitDebugRanges - Emit visible names into a debug ranges section.
///
void DwarfDebug::EmitDebugRanges() {
  // Start the dwarf ranges section.
  Asm->SwitchToDataSection(TAI->getDwarfRangesSection());
  Asm->EOL();
}

/// EmitDebugMacInfo - Emit visible names into a debug macinfo section.
///
void DwarfDebug::EmitDebugMacInfo() {
  if (const char *LineInfoDirective = TAI->getDwarfMacroInfoSection()) {
    // Start the dwarf macinfo section.
    Asm->SwitchToDataSection(LineInfoDirective);
    Asm->EOL();
  }
}

/// EmitDebugInlineInfo - Emit inline info using following format.
/// Section Header:
/// 1. length of section
/// 2. Dwarf version number
/// 3. address size.
///
/// Entries (one "entry" for each function that was inlined):
///
/// 1. offset into __debug_str section for MIPS linkage name, if exists;
///   otherwise offset into __debug_str for regular function name.
/// 2. offset into __debug_str section for regular function name.
/// 3. an unsigned LEB128 number indicating the number of distinct inlining
/// instances for the function.
///
/// The rest of the entry consists of a {die_offset, low_pc} pair for each
/// inlined instance; the die_offset points to the inlined_subroutine die in the
/// __debug_info section, and the low_pc is the starting address for the
/// inlining instance.
void DwarfDebug::EmitDebugInlineInfo() {
  if (!TAI->doesDwarfUsesInlineInfoSection())
    return;

  if (!ModuleCU)
    return;

  Asm->SwitchToDataSection(TAI->getDwarfDebugInlineSection());
  Asm->EOL();
  EmitDifference("debug_inlined_end", 1,
                 "debug_inlined_begin", 1, true);
  Asm->EOL("Length of Debug Inlined Information Entry");

  EmitLabel("debug_inlined_begin", 1);

  Asm->EmitInt16(dwarf::DWARF_VERSION); Asm->EOL("Dwarf Version");
  Asm->EmitInt8(TD->getPointerSize()); Asm->EOL("Address Size (in bytes)");

  for (DenseMap<GlobalVariable *, SmallVector<unsigned, 4> >::iterator
         I = InlineInfo.begin(), E = InlineInfo.end(); I != E; ++I) {
    GlobalVariable *GV = I->first;
    SmallVector<unsigned, 4> &Labels = I->second;
    DISubprogram SP(GV);
    std::string Name;
    std::string LName;

    SP.getLinkageName(LName);
    SP.getName(Name);

    if (LName.empty())
      Asm->EmitString(Name);
    else {
      // Skip special LLVM prefix that is used to inform the asm printer to not emit
      // usual symbol prefix before the symbol name. This happens for Objective-C
      // symbol names and symbol whose name is replaced using GCC's __asm__ attribute.
      if (LName[0] == 1)
        LName = &LName[1];
      Asm->EmitString(LName);
    }
    Asm->EOL("MIPS linkage name");

    Asm->EmitString(Name); Asm->EOL("Function name");

    Asm->EmitULEB128Bytes(Labels.size()); Asm->EOL("Inline count");

    for (SmallVector<unsigned, 4>::iterator LI = Labels.begin(),
           LE = Labels.end(); LI != LE; ++LI) {
      DIE *SP = ModuleCU->getDieMapSlotFor(GV);
      Asm->EmitInt32(SP->getOffset()); Asm->EOL("DIE offset");

      if (TD->getPointerSize() == sizeof(int32_t))
        O << TAI->getData32bitsDirective();
      else
        O << TAI->getData64bitsDirective();

      PrintLabelName("label", *LI); Asm->EOL("low_pc");
    }
  }

  EmitLabel("debug_inlined_end", 1);
  Asm->EOL();
}