lib/CodeGen/DwarfWriter.cpp

//===-- llvm/CodeGen/DwarfWriter.cpp - Dwarf Framework ----------*- C++ -*-===//
//
//                     The LLVM Compiler Infrastructure
//
// This file was developed by James M. Laskey and 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 "llvm/CodeGen/DwarfWriter.h"

#include "llvm/ADT/FoldingSet.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/UniqueVector.h"
#include "llvm/Module.h"
#include "llvm/Type.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/CodeGen/MachineDebugInfo.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineLocation.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/DataTypes.h"
#include "llvm/Support/Mangler.h"
#include "llvm/Target/TargetAsmInfo.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetFrameInfo.h"

#include <iostream>
#include <string>

using namespace llvm;
using namespace llvm::dwarf;

static cl::opt<bool>
DwarfVerbose("dwarf-verbose", cl::Hidden,
                              cl::desc("Add comments to Dwarf directives."));

namespace llvm {
  
//===----------------------------------------------------------------------===//

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

//===----------------------------------------------------------------------===//
/// Forward declarations.
///
class DIE;
class DIEValue;

//===----------------------------------------------------------------------===//
/// LEB 128 number encoding.

/// PrintULEB128 - Print a series of hexidecimal values (separated by commas)
/// representing an unsigned leb128 value.
static void PrintULEB128(std::ostream &O, unsigned Value) {
  do {
    unsigned Byte = Value & 0x7f;
    Value >>= 7;
    if (Value) Byte |= 0x80;
    O << "0x" << std::hex << Byte << std::dec;
    if (Value) O << ", ";
  } while (Value);
}

/// SizeULEB128 - Compute the number of bytes required for an unsigned leb128
/// value.
static unsigned SizeULEB128(unsigned Value) {
  unsigned Size = 0;
  do {
    Value >>= 7;
    Size += sizeof(int8_t);
  } while (Value);
  return Size;
}

/// PrintSLEB128 - Print a series of hexidecimal values (separated by commas)
/// representing a signed leb128 value.
static void PrintSLEB128(std::ostream &O, int Value) {
  int Sign = Value >> (8 * sizeof(Value) - 1);
  bool IsMore;
  
  do {
    unsigned Byte = Value & 0x7f;
    Value >>= 7;
    IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
    if (IsMore) Byte |= 0x80;
    O << "0x" << std::hex << Byte << std::dec;
    if (IsMore) O << ", ";
  } while (IsMore);
}

/// SizeSLEB128 - Compute the number of bytes required for a signed leb128
/// value.
static unsigned SizeSLEB128(int Value) {
  unsigned Size = 0;
  int Sign = Value >> (8 * sizeof(Value) - 1);
  bool IsMore;
  
  do {
    unsigned Byte = Value & 0x7f;
    Value >>= 7;
    IsMore = Value != Sign || ((Byte ^ Sign) & 0x40) != 0;
    Size += sizeof(int8_t);
  } while (IsMore);
  return Size;
}

//===----------------------------------------------------------------------===//
/// DWLabel - Labels are used to track locations in the assembler file.
/// Labels appear in the form <prefix>debug_<Tag><Number>, where the tag is a
/// category of label (Ex. location) and number is a value unique in that
/// category.
class DWLabel {
public:
  /// Tag - Label category tag. Should always be a staticly declared C string.
  ///
  const char *Tag;
  
  /// Number - Value to make label unique.
  ///
  unsigned    Number;

  DWLabel(const char *T, unsigned N) : Tag(T), Number(N) {}
  
  void Profile(FoldingSetNodeID &ID) const {
    ID.AddString(std::string(Tag));
    ID.AddInteger(Number);
  }
  
#ifndef NDEBUG
  void print(std::ostream &O) const {
    O << ".debug_" << Tag;
    if (Number) O << Number;
  }
#endif
};

//===----------------------------------------------------------------------===//
/// DIEAbbrevData - Dwarf abbreviation data, describes the one attribute of a
/// Dwarf abbreviation.
class DIEAbbrevData {
private:
  /// Attribute - Dwarf attribute code.
  ///
  unsigned Attribute;
  
  /// Form - Dwarf form code.
  ///              
  unsigned Form;                      
  
public:
  DIEAbbrevData(unsigned A, unsigned F)
  : Attribute(A)
  , Form(F)
  {}
  
  // Accessors.
  unsigned getAttribute() const { return Attribute; }
  unsigned getForm()      const { return Form; }

  /// Profile - Used to gather unique data for the abbreviation folding set.
  ///
  void Profile(FoldingSetNodeID &ID)const  {
    ID.AddInteger(Attribute);
    ID.AddInteger(Form);
  }
};

//===----------------------------------------------------------------------===//
/// DIEAbbrev - Dwarf abbreviation, describes the organization of a debug
/// information object.
class DIEAbbrev : public FoldingSetNode {
private:
  /// Tag - Dwarf tag code.
  ///
  unsigned Tag;
  
  /// Unique number for node.
  ///
  unsigned Number;

  /// ChildrenFlag - Dwarf children flag.
  ///
  unsigned ChildrenFlag;

  /// Data - Raw data bytes for abbreviation.
  ///
  std::vector<DIEAbbrevData> Data;

public:

  DIEAbbrev(unsigned T, unsigned C)
  : Tag(T)
  , ChildrenFlag(C)
  , Data()
  {}
  ~DIEAbbrev() {}
  
  // Accessors.
  unsigned getTag()                           const { return Tag; }
  unsigned getNumber()                        const { return Number; }
  unsigned getChildrenFlag()                  const { return ChildrenFlag; }
  const std::vector<DIEAbbrevData> &getData() const { return Data; }
  void setTag(unsigned T)                           { Tag = T; }
  void setChildrenFlag(unsigned CF)                 { ChildrenFlag = CF; }
  void setNumber(unsigned N)                        { Number = N; }
  
  /// AddAttribute - Adds another set of attribute information to the
  /// abbreviation.
  void AddAttribute(unsigned Attribute, unsigned Form) {
    Data.push_back(DIEAbbrevData(Attribute, Form));
  }
  
  /// AddFirstAttribute - Adds a set of attribute information to the front
  /// of the abbreviation.
  void AddFirstAttribute(unsigned Attribute, unsigned Form) {
    Data.insert(Data.begin(), DIEAbbrevData(Attribute, Form));
  }
  
  /// Profile - Used to gather unique data for the abbreviation folding set.
  ///
  void Profile(FoldingSetNodeID &ID) {
    ID.AddInteger(Tag);
    ID.AddInteger(ChildrenFlag);
    
    // For each attribute description.
    for (unsigned i = 0, N = Data.size(); i < N; ++i)
      Data[i].Profile(ID);
  }
  
  /// Emit - Print the abbreviation using the specified Dwarf writer.
  ///
  void Emit(const Dwarf &DW) const; 
      
#ifndef NDEBUG
  void print(std::ostream &O);
  void dump();
#endif
};

//===----------------------------------------------------------------------===//
/// DIE - A structured debug information entry.  Has an abbreviation which
/// describes it's organization.
class DIE : public FoldingSetNode {
protected:
  /// Abbrev - Buffer for constructing abbreviation.
  ///
  DIEAbbrev Abbrev;
  
  /// Offset - Offset in debug info section.
  ///
  unsigned Offset;
  
  /// Size - Size of instance + children.
  ///
  unsigned Size;
  
  /// Children DIEs.
  ///
  std::vector<DIE *> Children;
  
  /// Attributes values.
  ///
  std::vector<DIEValue *> Values;
  
public:
  DIE(unsigned Tag)
  : Abbrev(Tag, DW_CHILDREN_no)
  , Offset(0)
  , Size(0)
  , Children()
  , Values()
  {}
  virtual ~DIE();
  
  // Accessors.
  DIEAbbrev &getAbbrev()                           { return Abbrev; }
  unsigned   getAbbrevNumber()               const {
    return Abbrev.getNumber();
  }
  unsigned getOffset()                       const { return Offset; }
  unsigned getSize()                         const { return Size; }
  const std::vector<DIE *> &getChildren()    const { return Children; }
  const std::vector<DIEValue *> &getValues() const { return Values; }
  void setTag(unsigned Tag)                  { Abbrev.setTag(Tag); }
  void setOffset(unsigned O)                 { Offset = O; }
  void setSize(unsigned S)                   { Size = S; }
  
  /// AddValue - Add a value and attributes to a DIE.
  ///
  void AddValue(unsigned Attribute, unsigned Form, DIEValue *Value) {
    Abbrev.AddAttribute(Attribute, Form);
    Values.push_back(Value);
  }
  
  /// SiblingOffset - Return the offset of the debug information entry's
  /// sibling.
  unsigned SiblingOffset() const { return Offset + Size; }
  
  /// AddSiblingOffset - Add a sibling offset field to the front of the DIE.
  ///
  void AddSiblingOffset();

  /// AddChild - Add a child to the DIE.
  ///
  void AddChild(DIE *Child) {
    Abbrev.setChildrenFlag(DW_CHILDREN_yes);
    Children.push_back(Child);
  }
  
  /// Detach - Detaches objects connected to it after copying.
  ///
  void Detach() {
    Children.clear();
  }
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  void Profile(FoldingSetNodeID &ID) ;
      
#ifndef NDEBUG
  void print(std::ostream &O, unsigned IncIndent = 0);
  void dump();
#endif
};

//===----------------------------------------------------------------------===//
/// DIEValue - A debug information entry value.
///
class DIEValue : public FoldingSetNode {
public:
  enum {
    isInteger,
    isString,
    isLabel,
    isAsIsLabel,
    isDelta,
    isEntry,
    isBlock
  };
  
  /// Type - Type of data stored in the value.
  ///
  unsigned Type;
  
  DIEValue(unsigned T)
  : Type(T)
  {}
  virtual ~DIEValue() {}
  
  // Accessors
  unsigned getType()  const { return Type; }
  
  // Implement isa/cast/dyncast.
  static bool classof(const DIEValue *) { return true; }
  
  /// EmitValue - Emit value via the Dwarf writer.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const = 0;
  
  /// SizeOf - Return the size of a value in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const = 0;
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID) = 0;
      
#ifndef NDEBUG
  virtual void print(std::ostream &O) = 0;
  void dump();
#endif
};

//===----------------------------------------------------------------------===//
/// DWInteger - An integer value DIE.
/// 
class DIEInteger : public DIEValue {
private:
  uint64_t Integer;
  
public:
  DIEInteger(uint64_t I) : DIEValue(isInteger), Integer(I) {}

  // Implement isa/cast/dyncast.
  static bool classof(const DIEInteger *) { return true; }
  static bool classof(const DIEValue *I)  { return I->Type == isInteger; }
  
  /// BestForm - Choose the best form for integer.
  ///
  static unsigned BestForm(bool IsSigned, uint64_t Integer) {
    if (IsSigned) {
      if ((char)Integer == (signed)Integer)   return DW_FORM_data1;
      if ((short)Integer == (signed)Integer)  return DW_FORM_data2;
      if ((int)Integer == (signed)Integer)    return DW_FORM_data4;
    } else {
      if ((unsigned char)Integer == Integer)  return DW_FORM_data1;
      if ((unsigned short)Integer == Integer) return DW_FORM_data2;
      if ((unsigned int)Integer == Integer)   return DW_FORM_data4;
    }
    return DW_FORM_data8;
  }
    
  /// EmitValue - Emit integer of appropriate size.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of integer value in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const {
    switch (Form) {
    case DW_FORM_flag:  // Fall thru
    case DW_FORM_ref1:  // Fall thru
    case DW_FORM_data1: return sizeof(int8_t);
    case DW_FORM_ref2:  // Fall thru
    case DW_FORM_data2: return sizeof(int16_t);
    case DW_FORM_ref4:  // Fall thru
    case DW_FORM_data4: return sizeof(int32_t);
    case DW_FORM_ref8:  // Fall thru
    case DW_FORM_data8: return sizeof(int64_t);
    case DW_FORM_udata: return SizeULEB128(Integer);
    case DW_FORM_sdata: return SizeSLEB128(Integer);
    default: assert(0 && "DIE Value form not supported yet"); break;
    }
    return 0;
  }
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID) {
    ID.AddInteger(isInteger);
    ID.AddInteger(Integer);
  }
  
#ifndef NDEBUG
  virtual void print(std::ostream &O) {
    O << "Int: " << (int64_t)Integer
      << "  0x" << std::hex << Integer << std::dec;
  }
#endif
};

//===----------------------------------------------------------------------===//
/// DIEString - A string value DIE.
/// 
class DIEString : public DIEValue {
public:
  const std::string String;
  
  DIEString(const std::string &S) : DIEValue(isString), String(S) {}

  // Implement isa/cast/dyncast.
  static bool classof(const DIEString *) { return true; }
  static bool classof(const DIEValue *S) { return S->Type == isString; }
  
  /// EmitValue - Emit string value.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of string value in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const {
    return String.size() + sizeof(char); // sizeof('\0');
  }
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID) {
    ID.AddInteger(isString);
    ID.AddString(String);
  }
  
#ifndef NDEBUG
  virtual void print(std::ostream &O) {
    O << "Str: \"" << String << "\"";
  }
#endif
};

//===----------------------------------------------------------------------===//
/// DIEDwarfLabel - A Dwarf internal label expression DIE.
//
class DIEDwarfLabel : public DIEValue {
public:

  const DWLabel Label;
  
  DIEDwarfLabel(const DWLabel &L) : DIEValue(isLabel), Label(L) {}

  // Implement isa/cast/dyncast.
  static bool classof(const DIEDwarfLabel *)  { return true; }
  static bool classof(const DIEValue *L) { return L->Type == isLabel; }
  
  /// EmitValue - Emit label value.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of label value in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const;
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID) {
    ID.AddInteger(isLabel);
    Label.Profile(ID);
  }
  
#ifndef NDEBUG
  virtual void print(std::ostream &O) {
    O << "Lbl: ";
    Label.print(O);
  }
#endif
};


//===----------------------------------------------------------------------===//
/// DIEObjectLabel - A label to an object in code or data.
//
class DIEObjectLabel : public DIEValue {
public:
  const std::string Label;
  
  DIEObjectLabel(const std::string &L) : DIEValue(isAsIsLabel), Label(L) {}

  // Implement isa/cast/dyncast.
  static bool classof(const DIEObjectLabel *) { return true; }
  static bool classof(const DIEValue *L)    { return L->Type == isAsIsLabel; }
  
  /// EmitValue - Emit label value.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of label value in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const;
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID) {
    ID.AddInteger(isAsIsLabel);
    ID.AddString(Label);
  }

#ifndef NDEBUG
  virtual void print(std::ostream &O) {
    O << "Obj: " << Label;
  }
#endif
};

//===----------------------------------------------------------------------===//
/// DIEDelta - A simple label difference DIE.
/// 
class DIEDelta : public DIEValue {
public:
  const DWLabel LabelHi;
  const DWLabel LabelLo;
  
  DIEDelta(const DWLabel &Hi, const DWLabel &Lo)
  : DIEValue(isDelta), LabelHi(Hi), LabelLo(Lo) {}

  // Implement isa/cast/dyncast.
  static bool classof(const DIEDelta *)  { return true; }
  static bool classof(const DIEValue *D) { return D->Type == isDelta; }
  
  /// EmitValue - Emit delta value.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of delta value in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const;
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID){
    ID.AddInteger(isDelta);
    LabelHi.Profile(ID);
    LabelLo.Profile(ID);
  }

#ifndef NDEBUG
  virtual void print(std::ostream &O) {
    O << "Del: ";
    LabelHi.print(O);
    O << "-";
    LabelLo.print(O);
  }
#endif
};

//===----------------------------------------------------------------------===//
/// DIEntry - A pointer to another debug information entry.  An instance of this
/// class can also be used as a proxy for a debug information entry not yet
/// defined (ie. types.)
class DIEntry : public DIEValue {
public:
  DIE *Entry;
  
  DIEntry(DIE *E) : DIEValue(isEntry), Entry(E) {}
  
  // Implement isa/cast/dyncast.
  static bool classof(const DIEntry *)   { return true; }
  static bool classof(const DIEValue *E) { return E->Type == isEntry; }
  
  /// EmitValue - Emit debug information entry offset.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of debug information entry in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const {
    return sizeof(int32_t);
  }
  
  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID) {
    ID.AddInteger(isEntry);
    
    if (Entry) {
      ID.AddPointer(Entry);
    } else {
      ID.AddPointer(this);
    }
  }
  
#ifndef NDEBUG
  virtual void print(std::ostream &O) {
    O << "Die: 0x" << std::hex << (intptr_t)Entry << std::dec;
  }
#endif
};

//===----------------------------------------------------------------------===//
/// DIEBlock - A block of values.  Primarily used for location expressions.
//
class DIEBlock : public DIEValue, public DIE {
public:
  unsigned Size;                        // Size in bytes excluding size header.
  
  DIEBlock()
  : DIEValue(isBlock)
  , DIE(0)
  , Size(0)
  {}
  ~DIEBlock()  {
  }
  
  // Implement isa/cast/dyncast.
  static bool classof(const DIEBlock *)  { return true; }
  static bool classof(const DIEValue *E) { return E->Type == isBlock; }
  
  /// ComputeSize - calculate the size of the block.
  ///
  unsigned ComputeSize(Dwarf &DW);
  
  /// BestForm - Choose the best form for data.
  ///
  unsigned BestForm() const {
    if ((unsigned char)Size == Size)  return DW_FORM_block1;
    if ((unsigned short)Size == Size) return DW_FORM_block2;
    if ((unsigned int)Size == Size)   return DW_FORM_block4;
    return DW_FORM_block;
  }

  /// EmitValue - Emit block data.
  ///
  virtual void EmitValue(const Dwarf &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of block data in bytes.
  ///
  virtual unsigned SizeOf(const Dwarf &DW, unsigned Form) const;
  

  /// Profile - Used to gather unique data for the value folding set.
  ///
  virtual void Profile(FoldingSetNodeID &ID) {
    ID.AddInteger(isBlock);
    DIE::Profile(ID);
  }
  
#ifndef NDEBUG
  virtual void print(std::ostream &O) {
    O << "Blk: ";
    DIE::print(O, 5);
  }
#endif
};

//===----------------------------------------------------------------------===//
/// CompileUnit - This dwarf writer support class manages information associate
/// with a source file.
class CompileUnit {
private:
  /// Desc - Compile unit debug descriptor.
  ///
  CompileUnitDesc *Desc;
  
  /// ID - File identifier for source.
  ///
  unsigned ID;
  
  /// Die - Compile unit debug information entry.
  ///
  DIE *Die;
  
  /// DescToDieMap - Tracks the mapping of unit level debug informaton
  /// descriptors to debug information entries.
  std::map<DebugInfoDesc *, DIE *> DescToDieMap;

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

  /// Globals - A map of globally visible named entities for this unit.
  ///
  std::map<std::string, DIE *> Globals;

  /// DiesSet - Used to uniquely define dies within the compile unit.
  ///
  FoldingSet<DIE> DiesSet;
  
  /// Dies - List of all dies in the compile unit.
  ///
  std::vector<DIE *> Dies;
  
public:
  CompileUnit(CompileUnitDesc *CUD, unsigned I, DIE *D)
  : Desc(CUD)
  , ID(I)
  , Die(D)
  , DescToDieMap()
  , DescToDIEntryMap()
  , Globals()
  , DiesSet(InitDiesSetSize)
  , Dies()
  {}
  
  ~CompileUnit() {
    delete Die;
    
    for (unsigned i = 0, N = Dies.size(); i < N; ++i)
      delete Dies[i];
  }
  
  // Accessors.
  CompileUnitDesc *getDesc() const { return Desc; }
  unsigned getID()           const { return ID; }
  DIE* getDie()              const { return Die; }
  std::map<std::string, 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 descriptor.
  DIE *&getDieMapSlotFor(DebugInfoDesc *DD) {
    return DescToDieMap[DD];
  }
  
  /// getDIEntrySlotFor - Returns the debug information entry proxy slot for the
  /// specified debug descriptor.
  DIEntry *&getDIEntrySlotFor(DebugInfoDesc *DD) {
    return DescToDIEntryMap[DD];
  }
  
  /// 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;
  }
};

//===----------------------------------------------------------------------===//
/// Dwarf - Emits Dwarf debug and exception handling directives. 
///
class Dwarf {

private:

  //===--------------------------------------------------------------------===//
  // Core attributes used by the Dwarf  writer.
  //
  
  //
  /// O - Stream to .s file.
  ///
  std::ostream &O;

  /// Asm - Target of Dwarf emission.
  ///
  AsmPrinter *Asm;
  
  /// TAI - Target Asm Printer.
  const TargetAsmInfo *TAI;
  
  /// TD - Target data.
  const TargetData *TD;
  
  /// RI - Register Information.
  const MRegisterInfo *RI;
  
  /// M - Current module.
  ///
  Module *M;
  
  /// MF - Current machine function.
  ///
  MachineFunction *MF;
  
  /// DebugInfo - Collected debug information.
  ///
  MachineDebugInfo *DebugInfo;
  
  /// didInitial - Flag to indicate if initial emission has been done.
  ///
  bool didInitial;
  
  /// shouldEmit - Flag to indicate if debug information should be emitted.
  ///
  bool shouldEmit;
  
  /// SubprogramCount - The running count of functions being compiled.
  ///
  unsigned SubprogramCount;
  
  //===--------------------------------------------------------------------===//
  // Attributes used to construct specific Dwarf sections.
  //
  
  /// CompileUnits - All the compile units involved in this build.  The index
  /// of each entry in this vector corresponds to the sources in DebugInfo.
  std::vector<CompileUnit *> CompileUnits;
  
  /// AbbreviationsSet - Used to uniquely define abbreviations.
  ///
  FoldingSet<DIEAbbrev> AbbreviationsSet;

  /// Abbreviations - A list of all the unique abbreviations in use.
  ///
  std::vector<DIEAbbrev *> Abbreviations;
  
  /// ValuesSet - Used to uniquely define values.
  ///
  FoldingSet<DIEValue> ValuesSet;
  
  /// Values - A list of all the unique values in use.
  ///
  std::vector<DIEValue *> Values;
  
  /// StringPool - A UniqueVector of strings used by indirect references.
  ///
  UniqueVector<std::string> StringPool;

  /// UnitMap - Map debug information descriptor to compile unit.
  ///
  std::map<DebugInfoDesc *, CompileUnit *> DescToUnitMap;
  
  /// SectionMap - Provides a unique id per text section.
  ///
  UniqueVector<std::string> SectionMap;
  
  /// SectionSourceLines - Tracks line numbers per text section.
  ///
  std::vector<std::vector<SourceLineInfo> > SectionSourceLines;


public:

  //===--------------------------------------------------------------------===//
  // Emission and print routines
  //

  /// PrintHex - Print a value as a hexidecimal value.
  ///
  void PrintHex(int Value) const { 
    O << "0x" << std::hex << Value << std::dec;
  }

  /// EOL - Print a newline character to asm stream.  If a comment is present
  /// then it will be printed first.  Comments should not contain '\n'.
  void EOL(const std::string &Comment) const {
    if (DwarfVerbose && !Comment.empty()) {
      O << "\t"
        << TAI->getCommentString()
        << " "
        << Comment;
    }
    O << "\n";
  }
  
  /// EmitAlign - Print a align directive.
  ///
  void EmitAlign(unsigned Alignment) const {
    O << TAI->getAlignDirective() << Alignment << "\n";
  }
                                        
  /// EmitULEB128Bytes - Emit an assembler byte data directive to compose an
  /// unsigned leb128 value.
  void EmitULEB128Bytes(unsigned Value) const {
    if (TAI->hasLEB128()) {
      O << "\t.uleb128\t"
        << Value;
    } else {
      O << TAI->getData8bitsDirective();
      PrintULEB128(O, Value);
    }
  }
  
  /// EmitSLEB128Bytes - print an assembler byte data directive to compose a
  /// signed leb128 value.
  void EmitSLEB128Bytes(int Value) const {
    if (TAI->hasLEB128()) {
      O << "\t.sleb128\t"
        << Value;
    } else {
      O << TAI->getData8bitsDirective();
      PrintSLEB128(O, Value);
    }
  }
  
  /// EmitInt8 - Emit a byte directive and value.
  ///
  void EmitInt8(int Value) const {
    O << TAI->getData8bitsDirective();
    PrintHex(Value & 0xFF);
  }

  /// EmitInt16 - Emit a short directive and value.
  ///
  void EmitInt16(int Value) const {
    O << TAI->getData16bitsDirective();
    PrintHex(Value & 0xFFFF);
  }

  /// EmitInt32 - Emit a long directive and value.
  ///
  void EmitInt32(int Value) const {
    O << TAI->getData32bitsDirective();
    PrintHex(Value);
  }

  /// EmitInt64 - Emit a long long directive and value.
  ///
  void EmitInt64(uint64_t Value) const {
    if (TAI->getData64bitsDirective()) {
      O << TAI->getData64bitsDirective();
      PrintHex(Value);
    } else {
      if (TD->isBigEndian()) {
        EmitInt32(unsigned(Value >> 32)); O << "\n";
        EmitInt32(unsigned(Value));
      } else {
        EmitInt32(unsigned(Value)); O << "\n";
        EmitInt32(unsigned(Value >> 32));
      }
    }
  }

  /// EmitString - Emit a string with quotes and a null terminator.
  /// Special characters are emitted properly.
  /// \literal (Eg. '\t') \endliteral
  void EmitString(const std::string &String) const {
    O << TAI->getAsciiDirective()
      << "\"";
    for (unsigned i = 0, N = String.size(); i < N; ++i) {
      unsigned char C = String[i];
      
      if (!isascii(C) || iscntrl(C)) {
        switch(C) {
        case '\b': O << "\\b"; break;
        case '\f': O << "\\f"; break;
        case '\n': O << "\\n"; break;
        case '\r': O << "\\r"; break;
        case '\t': O << "\\t"; break;
        default:
          O << '\\';
          O << char('0' + ((C >> 6) & 7));
          O << char('0' + ((C >> 3) & 7));
          O << char('0' + ((C >> 0) & 7));
          break;
        }
      } else if (C == '\"') {
        O << "\\\"";
      } else if (C == '\'') {
        O << "\\\'";
      } else {
       O << C;
      }
    }
    O << "\\0\"";
  }

  /// PrintLabelName - Print label name in form used by Dwarf writer.
  ///
  void PrintLabelName(DWLabel Label) const {
    PrintLabelName(Label.Tag, Label.Number);
  }
  void PrintLabelName(const char *Tag, unsigned Number) const {
    O << TAI->getPrivateGlobalPrefix()
      << "debug_"
      << Tag;
    if (Number) O << Number;
  }
  
  /// EmitLabel - Emit location label for internal use by Dwarf.
  ///
  void EmitLabel(DWLabel Label) const {
    EmitLabel(Label.Tag, Label.Number);
  }
  void EmitLabel(const char *Tag, unsigned Number) const {
    PrintLabelName(Tag, Number);
    O << ":\n";
  }
  
  /// EmitReference - Emit a reference to a label.
  ///
  void EmitReference(DWLabel Label) const {
    EmitReference(Label.Tag, Label.Number);
  }
  void EmitReference(const char *Tag, unsigned Number) const {
    if (TAI->getAddressSize() == 4)
      O << TAI->getData32bitsDirective();
    else
      O << TAI->getData64bitsDirective();
      
    PrintLabelName(Tag, Number);
  }
  void EmitReference(const std::string &Name) const {
    if (TAI->getAddressSize() == 4)
      O << TAI->getData32bitsDirective();
    else
      O << TAI->getData64bitsDirective();
      
    O << Name;
  }

  /// EmitDifference - Emit the difference between two labels.  Some
  /// assemblers do not behave with absolute expressions with data directives,
  /// so there is an option (needsSet) to use an intermediary set expression.
  void EmitDifference(DWLabel LabelHi, DWLabel LabelLo) const {
    EmitDifference(LabelHi.Tag, LabelHi.Number, LabelLo.Tag, LabelLo.Number);
  }
  void EmitDifference(const char *TagHi, unsigned NumberHi,
                      const char *TagLo, unsigned NumberLo) const {
    if (TAI->needsSet()) {
      static unsigned SetCounter = 0;
      
      O << "\t.set\t";
      PrintLabelName("set", SetCounter);
      O << ",";
      PrintLabelName(TagHi, NumberHi);
      O << "-";
      PrintLabelName(TagLo, NumberLo);
      O << "\n";
      
      if (TAI->getAddressSize() == sizeof(int32_t))
        O << TAI->getData32bitsDirective();
      else
        O << TAI->getData64bitsDirective();
        
      PrintLabelName("set", SetCounter);
      
      ++SetCounter;
    } else {
      if (TAI->getAddressSize() == sizeof(int32_t))
        O << TAI->getData32bitsDirective();
      else
        O << TAI->getData64bitsDirective();
        
      PrintLabelName(TagHi, NumberHi);
      O << "-";
      PrintLabelName(TagLo, NumberLo);
    }
  }
                      
  /// AssignAbbrevNumber - Define a unique number for the abbreviation.
  ///  
  void 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());
    }
  }

  /// NewString - Add a string to the constant pool and returns a label.
  ///
  DWLabel NewString(const std::string &String) {
    unsigned StringID = StringPool.insert(String);
    return DWLabel("string", StringID);
  }
  
  /// NewDIEntry - Creates a new DIEntry to be a proxy for a debug information
  /// entry.
  DIEntry *NewDIEntry(DIE *Entry = NULL) {
    DIEntry *Value;
    
    if (Entry) {
      FoldingSetNodeID ID;
      ID.AddPointer(Entry);
      void *Where;
      Value = static_cast<DIEntry *>(ValuesSet.FindNodeOrInsertPos(ID, Where));
      
      if (Value) return Value;
      
      Value = new DIEntry(Entry);
      ValuesSet.InsertNode(Value, Where);
    } else {
      Value = new DIEntry(Entry);
    }
    
    Values.push_back(Value);
    return Value;
  }
  
  /// SetDIEntry - Set a DIEntry once the debug information entry is defined.
  ///
  void SetDIEntry(DIEntry *Value, DIE *Entry) {
    Value->Entry = 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 AddUInt(DIE *Die, unsigned Attribute, unsigned Form, uint64_t Integer) {
    if (!Form) Form = DIEInteger::BestForm(false, Integer);

    FoldingSetNodeID ID;
    ID.AddInteger(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 AddSInt(DIE *Die, unsigned Attribute, unsigned Form, int64_t Integer) {
    if (!Form) Form = DIEInteger::BestForm(true, Integer);

    FoldingSetNodeID ID;
    ID.AddInteger((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 std::string attribute data and value.
  ///
  void AddString(DIE *Die, unsigned Attribute, unsigned Form,
                 const std::string &String) {
    FoldingSetNodeID ID;
    ID.AddString(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 AddLabel(DIE *Die, unsigned Attribute, unsigned Form,
                     const DWLabel &Label) {
    FoldingSetNodeID ID;
    Label.Profile(ID);
    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 AddObjectLabel(DIE *Die, unsigned Attribute, unsigned Form,
                      const std::string &Label) {
    FoldingSetNodeID ID;
    ID.AddString(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);
  }
      
  /// AddDelta - Add a label delta attribute data and value.
  ///
  void AddDelta(DIE *Die, unsigned Attribute, unsigned Form,
                          const DWLabel &Hi, const DWLabel &Lo) {
    FoldingSetNodeID ID;
    Hi.Profile(ID);
    Lo.Profile(ID);
    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);
  }
      
  /// AddDIEntry - Add a DIE attribute data and value.
  ///
  void AddDIEntry(DIE *Die, unsigned Attribute, unsigned Form, DIE *Entry) {
    Die->AddValue(Attribute, Form, NewDIEntry(Entry));
  }

  /// AddBlock - Add block data.
  ///
  void AddBlock(DIE *Die, unsigned Attribute, unsigned Form, DIEBlock *Block) {
    Block->ComputeSize(*this);
    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 {
      delete Block;
    }
  
    Die->AddValue(Attribute, Block->BestForm(), Value);
  }

private:

  /// AddSourceLine - Add location information to specified debug information
  /// entry.
  void AddSourceLine(DIE *Die, CompileUnitDesc *File, unsigned Line) {
    if (File && Line) {
      CompileUnit *FileUnit = FindCompileUnit(File);
      unsigned FileID = FileUnit->getID();
      AddUInt(Die, DW_AT_decl_file, 0, FileID);
      AddUInt(Die, DW_AT_decl_line, 0, Line);
    }
  }

  /// AddAddress - Add an address attribute to a die based on the location
  /// provided.
  void AddAddress(DIE *Die, unsigned Attribute,
                            const MachineLocation &Location) {
    unsigned Reg = RI->getDwarfRegNum(Location.getRegister());
    DIEBlock *Block = new DIEBlock();
    
    if (Location.isRegister()) {
      if (Reg < 32) {
        AddUInt(Block, 0, DW_FORM_data1, DW_OP_reg0 + Reg);
      } else {
        AddUInt(Block, 0, DW_FORM_data1, DW_OP_regx);
        AddUInt(Block, 0, DW_FORM_udata, Reg);
      }
    } else {
      if (Reg < 32) {
        AddUInt(Block, 0, DW_FORM_data1, DW_OP_breg0 + Reg);
      } else {
        AddUInt(Block, 0, DW_FORM_data1, DW_OP_bregx);
        AddUInt(Block, 0, DW_FORM_udata, Reg);
      }
      AddUInt(Block, 0, DW_FORM_sdata, Location.getOffset());
    }
    
    AddBlock(Die, Attribute, 0, Block);
  }
  
  /// AddBasicType - Add a new basic type attribute to the specified entity.
  ///
  void AddBasicType(DIE *Entity, CompileUnit *Unit,
                    const std::string &Name,
                    unsigned Encoding, unsigned Size) {
    DIE *Die = ConstructBasicType(Unit, Name, Encoding, Size);
    AddDIEntry(Entity, DW_AT_type, DW_FORM_ref4, Die);
  }
  
  /// ConstructBasicType - Construct a new basic type.
  ///
  DIE *ConstructBasicType(CompileUnit *Unit,
                          const std::string &Name,
                          unsigned Encoding, unsigned Size) {
    DIE Buffer(DW_TAG_base_type);
    AddUInt(&Buffer, DW_AT_byte_size, 0, Size);
    AddUInt(&Buffer, DW_AT_encoding, DW_FORM_data1, Encoding);
    if (!Name.empty()) AddString(&Buffer, DW_AT_name, DW_FORM_string, Name);
    return Unit->AddDie(Buffer);
  }
  
  /// AddPointerType - Add a new pointer type attribute to the specified entity.
  ///
  void AddPointerType(DIE *Entity, CompileUnit *Unit, const std::string &Name) {
    DIE *Die = ConstructPointerType(Unit, Name);
    AddDIEntry(Entity, DW_AT_type, DW_FORM_ref4, Die);
  }
  
  /// ConstructPointerType - Construct a new pointer type.
  ///
  DIE *ConstructPointerType(CompileUnit *Unit, const std::string &Name) {
    DIE Buffer(DW_TAG_pointer_type);
    AddUInt(&Buffer, DW_AT_byte_size, 0, TAI->getAddressSize());
    if (!Name.empty()) AddString(&Buffer, DW_AT_name, DW_FORM_string, Name);
    return Unit->AddDie(Buffer);
  }
  
  /// AddType - Add a new type attribute to the specified entity.
  ///
  void AddType(DIE *Entity, TypeDesc *TyDesc, CompileUnit *Unit) {
    if (!TyDesc) {
      AddBasicType(Entity, Unit, "", DW_ATE_signed, 4);
    } else {
      // Check for pre-existence.
      DIEntry *&Slot = Unit->getDIEntrySlotFor(TyDesc);
      
      // If it exists then use the existing value.
      if (Slot) {
        Entity->AddValue(DW_AT_type, DW_FORM_ref4, Slot);
        return;
      }
      
      if (SubprogramDesc *SubprogramTy = dyn_cast<SubprogramDesc>(TyDesc)) {
        // FIXME - Not sure why programs and variables are coming through here.
        // Short cut for handling subprogram types (not really a TyDesc.)
        AddPointerType(Entity, Unit, SubprogramTy->getName());
      } else if (GlobalVariableDesc *GlobalTy =
                                         dyn_cast<GlobalVariableDesc>(TyDesc)) {
        // FIXME - Not sure why programs and variables are coming through here.
        // Short cut for handling global variable types (not really a TyDesc.)
        AddPointerType(Entity, Unit, GlobalTy->getName());
      } else {  
        // Set up proxy.
        Slot = NewDIEntry();
        
        // Construct type.
        DIE Buffer(DW_TAG_base_type);
        ConstructType(Buffer, TyDesc, Unit);
        
        // Add debug information entry to entity and unit.
        DIE *Die = Unit->AddDie(Buffer);
        SetDIEntry(Slot, Die);
        Entity->AddValue(DW_AT_type, DW_FORM_ref4, Slot);
      }
    }
  }
  
  /// ConstructType - Adds all the required attributes to the type.
  ///
  void ConstructType(DIE &Buffer, TypeDesc *TyDesc, CompileUnit *Unit) {
    // Get core information.
    const std::string &Name = TyDesc->getName();
    uint64_t Size = TyDesc->getSize() >> 3;
    
    if (BasicTypeDesc *BasicTy = dyn_cast<BasicTypeDesc>(TyDesc)) {
      // Fundamental types like int, float, bool
      Buffer.setTag(DW_TAG_base_type);
      AddUInt(&Buffer, DW_AT_encoding,  DW_FORM_data1, BasicTy->getEncoding());
    } else if (DerivedTypeDesc *DerivedTy = dyn_cast<DerivedTypeDesc>(TyDesc)) {
      // Pointers, tyepdefs et al. 
      Buffer.setTag(DerivedTy->getTag());
      // Map to main type, void will not have a type.
      if (TypeDesc *FromTy = DerivedTy->getFromType())
        AddType(&Buffer, FromTy, Unit);
    } else if (CompositeTypeDesc *CompTy = dyn_cast<CompositeTypeDesc>(TyDesc)){
      // Fetch tag.
      unsigned Tag = CompTy->getTag();
      
      // Set tag accordingly.
      if (Tag == DW_TAG_vector_type)
        Buffer.setTag(DW_TAG_array_type);
      else 
        Buffer.setTag(Tag);

      std::vector<DebugInfoDesc *> &Elements = CompTy->getElements();
      
      switch (Tag) {
      case DW_TAG_vector_type:
        AddUInt(&Buffer, DW_AT_GNU_vector, DW_FORM_flag, 1);
        // Fall thru
      case DW_TAG_array_type: {
        // Add element type.
        if (TypeDesc *FromTy = CompTy->getFromType())
          AddType(&Buffer, FromTy, Unit);
        
        // Don't emit size attribute.
        Size = 0;
        
        // Construct an anonymous type for index type.
        DIE *IndexTy = ConstructBasicType(Unit, "", DW_ATE_signed, 4);
      
        // Add subranges to array type.
        for(unsigned i = 0, N = Elements.size(); i < N; ++i) {
          SubrangeDesc *SRD = cast<SubrangeDesc>(Elements[i]);
          int64_t Lo = SRD->getLo();
          int64_t Hi = SRD->getHi();
          DIE *Subrange = new DIE(DW_TAG_subrange_type);
          
          // If a range is available.
          if (Lo != Hi) {
            AddDIEntry(Subrange, DW_AT_type, DW_FORM_ref4, IndexTy);
            // Only add low if non-zero.
            if (Lo) AddSInt(Subrange, DW_AT_lower_bound, 0, Lo);
            AddSInt(Subrange, DW_AT_upper_bound, 0, Hi);
          }
          
          Buffer.AddChild(Subrange);
        }
        break;
      }
      case DW_TAG_structure_type:
      case DW_TAG_union_type: {
        // Add elements to structure type.
        for(unsigned i = 0, N = Elements.size(); i < N; ++i) {
          DebugInfoDesc *Element = Elements[i];
          
          if (DerivedTypeDesc *MemberDesc = dyn_cast<DerivedTypeDesc>(Element)){
            // Add field or base class.
            
            unsigned Tag = MemberDesc->getTag();
          
            // Extract the basic information.
            const std::string &Name = MemberDesc->getName();
            uint64_t Size = MemberDesc->getSize();
            uint64_t Align = MemberDesc->getAlign();
            uint64_t Offset = MemberDesc->getOffset();
       
            // Construct member debug information entry.
            DIE *Member = new DIE(Tag);
            
            // Add name if not "".
            if (!Name.empty())
              AddString(Member, DW_AT_name, DW_FORM_string, Name);
            // Add location if available.
            AddSourceLine(Member, MemberDesc->getFile(), MemberDesc->getLine());
            
            // Most of the time the field info is the same as the members.
            uint64_t FieldSize = Size;
            uint64_t FieldAlign = Align;
            uint64_t FieldOffset = Offset;
            
            if (TypeDesc *FromTy = MemberDesc->getFromType()) {
              AddType(Member, FromTy, Unit);
              FieldSize = FromTy->getSize();
              FieldAlign = FromTy->getSize();
            }
            
            // Unless we have a bit field.
            if (Tag == DW_TAG_member && FieldSize != Size) {
              // Construct the alignment mask.
              uint64_t AlignMask = ~(FieldAlign - 1);
              // Determine the high bit + 1 of the declared size.
              uint64_t HiMark = (Offset + FieldSize) & AlignMask;
              // Work backwards to determine the base offset of the field.
              FieldOffset = HiMark - FieldSize;
              // Now normalize offset to the field.
              Offset -= FieldOffset;
              
              // Maybe we need to work from the other end.
              if (TD->isLittleEndian()) Offset = FieldSize - (Offset + Size);
              
              // Add size and offset.
              AddUInt(Member, DW_AT_byte_size, 0, FieldSize >> 3);
              AddUInt(Member, DW_AT_bit_size, 0, Size);
              AddUInt(Member, DW_AT_bit_offset, 0, Offset);
            }
            
            // Add computation for offset.
            DIEBlock *Block = new DIEBlock();
            AddUInt(Block, 0, DW_FORM_data1, DW_OP_plus_uconst);
            AddUInt(Block, 0, DW_FORM_udata, FieldOffset >> 3);
            AddBlock(Member, DW_AT_data_member_location, 0, Block);

            // Add accessibility (public default unless is base class.
            if (MemberDesc->isProtected()) {
              AddUInt(Member, DW_AT_accessibility, 0, DW_ACCESS_protected);
            } else if (MemberDesc->isPrivate()) {
              AddUInt(Member, DW_AT_accessibility, 0, DW_ACCESS_private);
            } else if (Tag == DW_TAG_inheritance) {
              AddUInt(Member, DW_AT_accessibility, 0, DW_ACCESS_public);
            }
            
            Buffer.AddChild(Member);
          } else if (GlobalVariableDesc *StaticDesc =
                                        dyn_cast<GlobalVariableDesc>(Element)) {
            // Add static member.
            
            // Construct member debug information entry.
            DIE *Static = new DIE(DW_TAG_variable);
            
            // Add name and mangled name.
            const std::string &Name = StaticDesc->getDisplayName();
            const std::string &MangledName = StaticDesc->getName();
            AddString(Static, DW_AT_name, DW_FORM_string, Name);
            AddString(Static, DW_AT_MIPS_linkage_name, DW_FORM_string,
                              MangledName);
            
            // Add location.
            AddSourceLine(Static, StaticDesc->getFile(), StaticDesc->getLine());
           
            // Add type.
            if (TypeDesc *StaticTy = StaticDesc->getType())
              AddType(Static, StaticTy, Unit);
            
            // Add flags.
            AddUInt(Static, DW_AT_external, DW_FORM_flag, 1);
            AddUInt(Static, DW_AT_declaration, DW_FORM_flag, 1);
            
            Buffer.AddChild(Static);
          } else if (SubprogramDesc *MethodDesc =
                                            dyn_cast<SubprogramDesc>(Element)) {
            // Add member function.
            
            // Construct member debug information entry.
            DIE *Method = new DIE(DW_TAG_subprogram);
           
            // Add name and mangled name.
            const std::string &Name = MethodDesc->getDisplayName();
            const std::string &MangledName = MethodDesc->getName();
            bool IsCTor = false;
            
            if (Name.empty()) {
              AddString(Method, DW_AT_name, DW_FORM_string, MangledName);            
              IsCTor = TyDesc->getName() == MangledName;
            } else {
              AddString(Method, DW_AT_name, DW_FORM_string, Name);            
              AddString(Method, DW_AT_MIPS_linkage_name, DW_FORM_string,
                                MangledName);
            }
            
            // Add location.
            AddSourceLine(Method, MethodDesc->getFile(), MethodDesc->getLine());
           
            // Add type.
            if (CompositeTypeDesc *MethodTy =
                   dyn_cast_or_null<CompositeTypeDesc>(MethodDesc->getType())) {
              // Get argument information.
              std::vector<DebugInfoDesc *> &Args = MethodTy->getElements();
             
              // If not a ctor.
              if (!IsCTor) {
                // Add return type.
                AddType(Method, dyn_cast<TypeDesc>(Args[0]), Unit);
              }
              
              // Add arguments.
              for(unsigned i = 1, N = Args.size(); i < N; ++i) {
                DIE *Arg = new DIE(DW_TAG_formal_parameter);
                AddType(Arg, cast<TypeDesc>(Args[i]), Unit);
                AddUInt(Arg, DW_AT_artificial, DW_FORM_flag, 1);
                Method->AddChild(Arg);
              }
            }

            // Add flags.
            AddUInt(Method, DW_AT_external, DW_FORM_flag, 1);
            AddUInt(Method, DW_AT_declaration, DW_FORM_flag, 1);
              
            Buffer.AddChild(Method);
          }
        }
        break;
      }
      case DW_TAG_enumeration_type: {
        // Add enumerators to enumeration type.
        for(unsigned i = 0, N = Elements.size(); i < N; ++i) {
          EnumeratorDesc *ED = cast<EnumeratorDesc>(Elements[i]);
          const std::string &Name = ED->getName();
          int64_t Value = ED->getValue();
          DIE *Enumerator = new DIE(DW_TAG_enumerator);
          AddString(Enumerator, DW_AT_name, DW_FORM_string, Name);
          AddSInt(Enumerator, DW_AT_const_value, DW_FORM_sdata, Value);
          Buffer.AddChild(Enumerator);
        }

        break;
      }
      case DW_TAG_subroutine_type: {
        // Add prototype flag.
        AddUInt(&Buffer, DW_AT_prototyped, DW_FORM_flag, 1);
        // Add return type.
        AddType(&Buffer, dyn_cast<TypeDesc>(Elements[0]), Unit);
        
        // Add arguments.
        for(unsigned i = 1, N = Elements.size(); i < N; ++i) {
          DIE *Arg = new DIE(DW_TAG_formal_parameter);
          AddType(Arg, cast<TypeDesc>(Elements[i]), Unit);
          Buffer.AddChild(Arg);
        }
        
        break;
      }
      default: break;
      }
    }
   
    // Add size if non-zero (derived types don't have a size.)
    if (Size) AddUInt(&Buffer, DW_AT_byte_size, 0, Size);
    // Add name if not anonymous or intermediate type.
    if (!Name.empty()) AddString(&Buffer, DW_AT_name, DW_FORM_string, Name);
    // Add source line info if available.
    AddSourceLine(&Buffer, TyDesc->getFile(), TyDesc->getLine());
  }

  /// NewCompileUnit - Create new compile unit and it's debug information entry.
  ///
  CompileUnit *NewCompileUnit(CompileUnitDesc *UnitDesc, unsigned ID) {
    // Construct debug information entry.
    DIE *Die = new DIE(DW_TAG_compile_unit);
    AddDelta(Die, DW_AT_stmt_list, DW_FORM_data4, DWLabel("section_line", 0),
                                                  DWLabel("section_line", 0));
    AddString(Die, DW_AT_producer,  DW_FORM_string, UnitDesc->getProducer());
    AddUInt  (Die, DW_AT_language,  DW_FORM_data1,  UnitDesc->getLanguage());
    AddString(Die, DW_AT_name,      DW_FORM_string, UnitDesc->getFileName());
    AddString(Die, DW_AT_comp_dir,  DW_FORM_string, UnitDesc->getDirectory());
    
    // Construct compile unit.
    CompileUnit *Unit = new CompileUnit(UnitDesc, ID, Die);
    
    // Add Unit to compile unit map.
    DescToUnitMap[UnitDesc] = Unit;
    
    return Unit;
  }

  /// GetBaseCompileUnit - Get the main compile unit.
  ///
  CompileUnit *GetBaseCompileUnit() const {
    CompileUnit *Unit = CompileUnits[0];
    assert(Unit && "Missing compile unit.");
    return Unit;
  }

  /// FindCompileUnit - Get the compile unit for the given descriptor.
  ///
  CompileUnit *FindCompileUnit(CompileUnitDesc *UnitDesc) {
    CompileUnit *Unit = DescToUnitMap[UnitDesc];
    assert(Unit && "Missing compile unit.");
    return Unit;
  }

  /// NewGlobalVariable - Add a new global variable DIE.
  ///
  DIE *NewGlobalVariable(GlobalVariableDesc *GVD) {
    // Get the compile unit context.
    CompileUnitDesc *UnitDesc =
      static_cast<CompileUnitDesc *>(GVD->getContext());
    CompileUnit *Unit = FindCompileUnit(UnitDesc);

    // Check for pre-existence.
    DIE *&Slot = Unit->getDieMapSlotFor(GVD);
    if (Slot) return Slot;
    
    // Get the global variable itself.
    GlobalVariable *GV = GVD->getGlobalVariable();

    const std::string &Name = GVD->hasMangledName() ? GVD->getDisplayName()
                                                    : GVD->getName();
    const std::string &MangledName = GVD->hasMangledName() ? GVD->getName()
                                                           : "";
    // Create the global's variable DIE.
    DIE *VariableDie = new DIE(DW_TAG_variable);
    AddString(VariableDie, DW_AT_name, DW_FORM_string, Name);
    if (!MangledName.empty()) {
      AddString(VariableDie, DW_AT_MIPS_linkage_name, DW_FORM_string,
                             MangledName);
    }
    AddType(VariableDie, GVD->getType(), Unit); 
    AddUInt(VariableDie, DW_AT_external, DW_FORM_flag, 1);
    
    // Add source line info if available.
    AddSourceLine(VariableDie, UnitDesc, GVD->getLine());
    
    // Work up linkage name.
    const std::string LinkageName = Asm->getGlobalLinkName(GV);

    // Add address.
    DIEBlock *Block = new DIEBlock();
    AddUInt(Block, 0, DW_FORM_data1, DW_OP_addr);
    AddObjectLabel(Block, 0, DW_FORM_udata, LinkageName);
    AddBlock(VariableDie, DW_AT_location,  0, Block);
    
    // Add to map.
    Slot = VariableDie;
   
    // Add to context owner.
    Unit->getDie()->AddChild(VariableDie);
    
    // Expose as global.
    // FIXME - need to check external flag.
    Unit->AddGlobal(Name, VariableDie);
    
    return VariableDie;
  }

  /// NewSubprogram - Add a new subprogram DIE.
  ///
  DIE *NewSubprogram(SubprogramDesc *SPD) {
    // Get the compile unit context.
    CompileUnitDesc *UnitDesc =
      static_cast<CompileUnitDesc *>(SPD->getContext());
    CompileUnit *Unit = FindCompileUnit(UnitDesc);

    // Check for pre-existence.
    DIE *&Slot = Unit->getDieMapSlotFor(SPD);
    if (Slot) return Slot;
    
    // Gather the details (simplify add attribute code.)
    const std::string &Name = SPD->hasMangledName() ? SPD->getDisplayName()
                                                    : SPD->getName();
    const std::string &MangledName = SPD->hasMangledName() ? SPD->getName()
                                                           : "";
    unsigned IsExternal = SPD->isStatic() ? 0 : 1;
                                      
    DIE *SubprogramDie = new DIE(DW_TAG_subprogram);
    AddString(SubprogramDie, DW_AT_name, DW_FORM_string, Name);
    if (!MangledName.empty()) {
      AddString(SubprogramDie, DW_AT_MIPS_linkage_name, DW_FORM_string,
                               MangledName);
    }
    if (SPD->getType()) AddType(SubprogramDie, SPD->getType(), Unit);
    AddUInt(SubprogramDie, DW_AT_external, DW_FORM_flag, IsExternal);
    AddUInt(SubprogramDie, DW_AT_prototyped, DW_FORM_flag, 1);
    
    // Add source line info if available.
    AddSourceLine(SubprogramDie, UnitDesc, SPD->getLine());

    // Add to map.
    Slot = SubprogramDie;
   
    // Add to context owner.
    Unit->getDie()->AddChild(SubprogramDie);
    
    // Expose as global.
    Unit->AddGlobal(Name, SubprogramDie);
    
    return SubprogramDie;
  }

  /// NewScopeVariable - Create a new scope variable.
  ///
  DIE *NewScopeVariable(DebugVariable *DV, CompileUnit *Unit) {
    // Get the descriptor.
    VariableDesc *VD = DV->getDesc();

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

    // Define variable debug information entry.
    DIE *VariableDie = new DIE(Tag);
    AddString(VariableDie, DW_AT_name, DW_FORM_string, VD->getName());

    // Add source line info if available.
    AddSourceLine(VariableDie, VD->getFile(), VD->getLine());
    
    // Add variable type.
    AddType(VariableDie, VD->getType(), Unit); 
    
    // Add variable address.
    MachineLocation Location;
    RI->getLocation(*MF, DV->getFrameIndex(), Location);
    AddAddress(VariableDie, DW_AT_location, Location);
    
    return VariableDie;
  }

  /// ConstructScope - Construct the components of a scope.
  ///
  void ConstructScope(DebugScope *ParentScope,
                                   DIE *ParentDie, CompileUnit *Unit) {
    // Add variables to scope.
    std::vector<DebugVariable *> &Variables = ParentScope->getVariables();
    for (unsigned i = 0, N = Variables.size(); i < N; ++i) {
      DIE *VariableDie = NewScopeVariable(Variables[i], Unit);
      if (VariableDie) ParentDie->AddChild(VariableDie);
    }
    
    // Add nested scopes.
    std::vector<DebugScope *> &Scopes = ParentScope->getScopes();
    for (unsigned j = 0, M = Scopes.size(); j < M; ++j) {
      // Define the Scope debug information entry.
      DebugScope *Scope = Scopes[j];
      // FIXME - Ignore inlined functions for the time being.
      if (!Scope->getParent()) continue;
      
      unsigned StartID = DebugInfo->MappedLabel(Scope->getStartLabelID());
      unsigned EndID = DebugInfo->MappedLabel(Scope->getEndLabelID());
      
      // Ignore empty scopes.
      if (StartID == EndID && StartID != 0) continue;
      if (Scope->getScopes().empty() && Scope->getVariables().empty()) continue;
      
      DIE *ScopeDie = new DIE(DW_TAG_lexical_block);
      
      // Add the scope bounds.
      if (StartID) {
        AddLabel(ScopeDie, DW_AT_low_pc, DW_FORM_addr,
                           DWLabel("loc", StartID));
      } else {
        AddLabel(ScopeDie, DW_AT_low_pc, DW_FORM_addr,
                           DWLabel("func_begin", SubprogramCount));
      }
      if (EndID) {
        AddLabel(ScopeDie, DW_AT_high_pc, DW_FORM_addr,
                           DWLabel("loc", EndID));
      } else {
        AddLabel(ScopeDie, DW_AT_high_pc, DW_FORM_addr,
                           DWLabel("func_end", SubprogramCount));
      }
                         
      // Add the scope contents.
      ConstructScope(Scope, ScopeDie, Unit);
      ParentDie->AddChild(ScopeDie);
    }
  }

  /// ConstructRootScope - Construct the scope for the subprogram.
  ///
  void ConstructRootScope(DebugScope *RootScope) {
    // Exit if there is no root scope.
    if (!RootScope) return;
    
    // Get the subprogram debug information entry. 
    SubprogramDesc *SPD = cast<SubprogramDesc>(RootScope->getDesc());
    
    // Get the compile unit context.
    CompileUnitDesc *UnitDesc =
      static_cast<CompileUnitDesc *>(SPD->getContext());
    CompileUnit *Unit = FindCompileUnit(UnitDesc);
    
    // Get the subprogram die.
    DIE *SPDie = Unit->getDieMapSlotFor(SPD);
    assert(SPDie && "Missing subprogram descriptor");
    
    // Add the function bounds.
    AddLabel(SPDie, DW_AT_low_pc, DW_FORM_addr,
                    DWLabel("func_begin", SubprogramCount));
    AddLabel(SPDie, DW_AT_high_pc, DW_FORM_addr,
                    DWLabel("func_end", SubprogramCount));
    MachineLocation Location(RI->getFrameRegister(*MF));
    AddAddress(SPDie, DW_AT_frame_base, Location);
                    
    ConstructScope(RootScope, SPDie, Unit);
  }

  /// EmitInitial - Emit initial Dwarf declarations.  This is necessary for cc
  /// tools to recognize the object file contains Dwarf information.
  void EmitInitial() {
    // Check to see if we already emitted intial headers.
    if (didInitial) return;
    didInitial = true;
    
    // Dwarf sections base addresses.
    if (TAI->getDwarfRequiresFrameSection()) {
      Asm->SwitchToDataSection(TAI->getDwarfFrameSection());
      EmitLabel("section_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);
    Asm->SwitchToDataSection(TAI->getDwarfMacInfoSection());
    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->SwitchToTextSection(TAI->getTextSection());
    EmitLabel("text_begin", 0);
    Asm->SwitchToDataSection(TAI->getDataSection());
    EmitLabel("data_begin", 0);

    // Emit common frame information.
    EmitInitialDebugFrame();
  }

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

    // Emit the code (index) for the abbreviation.
    EmitULEB128Bytes(AbbrevNumber);
    EOL(std::string("Abbrev [" +
        utostr(AbbrevNumber) +
        "] 0x" + utohexstr(Die->getOffset()) +
        ":0x" + utohexstr(Die->getSize()) + " " +
        TagString(Abbrev->getTag())));
    
    const std::vector<DIEValue *> &Values = Die->getValues();
    const std::vector<DIEAbbrevData> &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 DW_AT_sibling: {
        EmitInt32(Die->SiblingOffset());
        break;
      }
      default: {
        // Emit an attribute using the defined form.
        Values[i]->EmitValue(*this, Form);
        break;
      }
      }
      
      EOL(AttributeString(Attr));
    }
    
    // Emit the DIE children if any.
    if (Abbrev->getChildrenFlag() == DW_CHILDREN_yes) {
      const std::vector<DIE *> &Children = Die->getChildren();
      
      for (unsigned j = 0, M = Children.size(); j < M; ++j) {
        EmitDIE(Children[j]);
      }
      
      EmitInt8(0); EOL("End Of Children Mark");
    }
  }

  /// SizeAndOffsetDie - Compute the size and offset of a DIE.
  ///
  unsigned 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 += SizeULEB128(AbbrevNumber);
    
    const std::vector<DIEValue *> &Values = Die->getValues();
    const std::vector<DIEAbbrevData> &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(*this, AbbrevData[i].getForm());
    }
    
    // Size the DIE children if any.
    if (!Children.empty()) {
      assert(Abbrev->getChildrenFlag() == 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 SizeAndOffsets() {
    // Process each compile unit.
    for (unsigned i = 0, N = CompileUnits.size(); i < N; ++i) {
      CompileUnit *Unit = CompileUnits[i];
      if (Unit->hasContent()) {
        // Compute size of compile unit header
        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(Unit->getDie(), Offset, (i + 1) == N);
      }
    }
  }

  /// EmitFrameMoves - Emit frame instructions to describe the layout of the
  /// frame.
  void EmitFrameMoves(const char *BaseLabel, unsigned BaseLabelID,
                                   std::vector<MachineMove *> &Moves) {
    for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
      MachineMove *Move = Moves[i];
      unsigned LabelID = DebugInfo->MappedLabel(Move->getLabelID());
      
      // Throw out move if the label is invalid.
      if (!LabelID) continue;
      
      const MachineLocation &Dst = Move->getDestination();
      const MachineLocation &Src = Move->getSource();
      
      // Advance row if new location.
      if (BaseLabel && LabelID && BaseLabelID != LabelID) {
        EmitInt8(DW_CFA_advance_loc4);
        EOL("DW_CFA_advance_loc4");
        EmitDifference("loc", LabelID, BaseLabel, BaseLabelID);
        EOL("");
        
        BaseLabelID = LabelID;
        BaseLabel = "loc";
      }
      
      int stackGrowth =
          Asm->TM.getFrameInfo()->getStackGrowthDirection() ==
            TargetFrameInfo::StackGrowsUp ?
              TAI->getAddressSize() : -TAI->getAddressSize();

      // If advancing cfa.
      if (Dst.isRegister() && Dst.getRegister() == MachineLocation::VirtualFP) {
        if (!Src.isRegister()) {
          if (Src.getRegister() == MachineLocation::VirtualFP) {
            EmitInt8(DW_CFA_def_cfa_offset);
            EOL("DW_CFA_def_cfa_offset");
          } else {
            EmitInt8(DW_CFA_def_cfa);
            EOL("DW_CFA_def_cfa");
            EmitULEB128Bytes(RI->getDwarfRegNum(Src.getRegister()));
            EOL("Register");
          }
          
          int Offset = Src.getOffset() / stackGrowth;
          
          EmitULEB128Bytes(Offset);
          EOL("Offset");
        } else {
          assert(0 && "Machine move no supported yet.");
        }
      } else {
        unsigned Reg = RI->getDwarfRegNum(Src.getRegister());
        int Offset = Dst.getOffset() / stackGrowth;
        
        if (Offset < 0) {
          EmitInt8(DW_CFA_offset_extended_sf);
          EOL("DW_CFA_offset_extended_sf");
          EmitULEB128Bytes(Reg);
          EOL("Reg");
          EmitSLEB128Bytes(Offset);
          EOL("Offset");
        } else if (Reg < 64) {
          EmitInt8(DW_CFA_offset + Reg);
          EOL("DW_CFA_offset + Reg");
          EmitULEB128Bytes(Offset);
          EOL("Offset");
        } else {
          EmitInt8(DW_CFA_offset_extended);
          EOL("DW_CFA_offset_extended");
          EmitULEB128Bytes(Reg);
          EOL("Reg");
          EmitULEB128Bytes(Offset);
          EOL("Offset");
        }
      }
    }
  }

  /// EmitDebugInfo - Emit the debug info section.
  ///
  void EmitDebugInfo() const {
    // Start debug info section.
    Asm->SwitchToDataSection(TAI->getDwarfInfoSection());
    
    // Process each compile unit.
    for (unsigned i = 0, N = CompileUnits.size(); i < N; ++i) {
      CompileUnit *Unit = CompileUnits[i];
      
      if (Unit->hasContent()) {
        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)
                               
        EmitInt32(ContentSize);  EOL("Length of Compilation Unit Info");
        EmitInt16(DWARF_VERSION); EOL("DWARF version number");
        EmitDifference("abbrev_begin", 0, "section_abbrev", 0);
        EOL("Offset Into Abbrev. Section");
        EmitInt8(TAI->getAddressSize()); EOL("Address Size (in bytes)");
      
        EmitDIE(Die);
        EmitLabel("info_end", Unit->getID());
      }
      
      O << "\n";
    }
  }

  /// EmitAbbreviations - Emit the abbreviation section.
  ///
  void 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.)
        EmitULEB128Bytes(Abbrev->getNumber()); EOL("Abbreviation Code");
        
        // Emit the abbreviations data.
        Abbrev->Emit(*this);
    
        O << "\n";
      }
      
      EmitLabel("abbrev_end", 0);
    
      O << "\n";
    }
  }

  /// EmitDebugLines - Emit source line information.
  ///
  void EmitDebugLines() const {
    // Minimum line delta, thus ranging from -10..(255-10).
    const int MinLineDelta = -(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);
    EOL("Length of Source Line Info");
    EmitLabel("line_begin", 0);
    
    EmitInt16(DWARF_VERSION); EOL("DWARF version number");
    
    EmitDifference("line_prolog_end", 0, "line_prolog_begin", 0);
    EOL("Prolog Length");
    EmitLabel("line_prolog_begin", 0);
    
    EmitInt8(1); EOL("Minimum Instruction Length");

    EmitInt8(1); EOL("Default is_stmt_start flag");

    EmitInt8(MinLineDelta);  EOL("Line Base Value (Special Opcodes)");
    
    EmitInt8(MaxLineDelta); EOL("Line Range Value (Special Opcodes)");

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

    const UniqueVector<std::string> &Directories = DebugInfo->getDirectories();
    const UniqueVector<SourceFileInfo>
      &SourceFiles = DebugInfo->getSourceFiles();

    // Emit directories.
    for (unsigned DirectoryID = 1, NDID = Directories.size();
                  DirectoryID <= NDID; ++DirectoryID) {
      EmitString(Directories[DirectoryID]); EOL("Directory");
    }
    EmitInt8(0); EOL("End of directories");
    
    // Emit files.
    for (unsigned SourceID = 1, NSID = SourceFiles.size();
                 SourceID <= NSID; ++SourceID) {
      const SourceFileInfo &SourceFile = SourceFiles[SourceID];
      EmitString(SourceFile.getName()); EOL("Source");
      EmitULEB128Bytes(SourceFile.getDirectoryID());  EOL("Directory #");
      EmitULEB128Bytes(0);  EOL("Mod date");
      EmitULEB128Bytes(0);  EOL("File size");
    }
    EmitInt8(0); EOL("End of files");
    
    EmitLabel("line_prolog_end", 0);
    
    // A sequence for each text section.
    for (unsigned j = 0, M = SectionSourceLines.size(); j < M; ++j) {
      // Isolate current sections line info.
      const std::vector<SourceLineInfo> &LineInfos = SectionSourceLines[j];
      
      if (DwarfVerbose) {
        O << "\t"
          << TAI->getCommentString() << " "
          << "Section "
          << SectionMap[j + 1].c_str() << "\n";
      }

      // 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 SourceLineInfo &LineInfo = LineInfos[i];
        unsigned LabelID = DebugInfo->MappedLabel(LineInfo.getLabelID());
        if (!LabelID) continue;
        
        if (DwarfVerbose) {
          unsigned SourceID = LineInfo.getSourceID();
          const SourceFileInfo &SourceFile = SourceFiles[SourceID];
          unsigned DirectoryID = SourceFile.getDirectoryID();
          O << "\t"
            << TAI->getCommentString() << " "
            << Directories[DirectoryID]
            << SourceFile.getName() << ":"
            << LineInfo.getLine() << "\n"; 
        }

        // Define the line address.
        EmitInt8(0); EOL("Extended Op");
        EmitInt8(4 + 1); EOL("Op size");
        EmitInt8(DW_LNE_set_address); EOL("DW_LNE_set_address");
        EmitReference("loc",  LabelID); EOL("Location label");
        
        // If change of source, then switch to the new source.
        if (Source != LineInfo.getSourceID()) {
          Source = LineInfo.getSourceID();
          EmitInt8(DW_LNS_set_file); EOL("DW_LNS_set_file");
          EmitULEB128Bytes(Source); 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.
            EmitInt8(Delta - MinLineDelta); EOL("Line Delta");
          } else {
            // ... otherwise use long hand.
            EmitInt8(DW_LNS_advance_line); EOL("DW_LNS_advance_line");
            EmitSLEB128Bytes(Offset); EOL("Line Offset");
            EmitInt8(DW_LNS_copy); EOL("DW_LNS_copy");
          }
        } else {
          // Copy the previous row (different address or source)
          EmitInt8(DW_LNS_copy); EOL("DW_LNS_copy");
        }
      }

      // Define last address of section.
      EmitInt8(0); EOL("Extended Op");
      EmitInt8(4 + 1); EOL("Op size");
      EmitInt8(DW_LNE_set_address); EOL("DW_LNE_set_address");
      EmitReference("section_end", j + 1); EOL("Section end label");

      // Mark end of matrix.
      EmitInt8(0); EOL("DW_LNE_end_sequence");
      EmitULEB128Bytes(1);  O << "\n";
      EmitInt8(1); O << "\n";
    }
    
    EmitLabel("line_end", 0);
    
    O << "\n";
  }
    
  /// EmitInitialDebugFrame - Emit common frame info into a debug frame section.
  ///
  void EmitInitialDebugFrame() {
    if (!TAI->getDwarfRequiresFrameSection())
      return;

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

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

    EmitLabel("frame_common", 0);
    EmitDifference("frame_common_end", 0,
                   "frame_common_begin", 0);
    EOL("Length of Common Information Entry");

    EmitLabel("frame_common_begin", 0);
    EmitInt32(DW_CIE_ID); EOL("CIE Identifier Tag");
    EmitInt8(DW_CIE_VERSION); EOL("CIE Version");
    EmitString("");  EOL("CIE Augmentation");
    EmitULEB128Bytes(1); EOL("CIE Code Alignment Factor");
    EmitSLEB128Bytes(stackGrowth); EOL("CIE Data Alignment Factor");   
    EmitInt8(RI->getDwarfRegNum(RI->getRARegister())); EOL("CIE RA Column");
    
    std::vector<MachineMove *> Moves;
    RI->getInitialFrameState(Moves);
    EmitFrameMoves(NULL, 0, Moves);
    for (unsigned i = 0, N = Moves.size(); i < N; ++i) delete Moves[i];

    EmitAlign(2);
    EmitLabel("frame_common_end", 0);
    
    O << "\n";
  }

  /// EmitFunctionDebugFrame - Emit per function frame info into a debug frame
  /// section.
  void EmitFunctionDebugFrame() {
    if (!TAI->getDwarfRequiresFrameSection())
      return;
       
    // Start the dwarf frame section.
    Asm->SwitchToDataSection(TAI->getDwarfFrameSection());
    
    EmitDifference("frame_end", SubprogramCount,
                   "frame_begin", SubprogramCount);
    EOL("Length of Frame Information Entry");
    
    EmitLabel("frame_begin", SubprogramCount);
    
    EmitDifference("frame_common", 0, "section_frame", 0);
    EOL("FDE CIE offset");

    EmitReference("func_begin", SubprogramCount); EOL("FDE initial location");
    EmitDifference("func_end", SubprogramCount,
                   "func_begin", SubprogramCount);
    EOL("FDE address range");
    
    std::vector<MachineMove *> &Moves = DebugInfo->getFrameMoves();
    
    EmitFrameMoves("func_begin", SubprogramCount, Moves);
    
    EmitAlign(2);
    EmitLabel("frame_end", SubprogramCount);

    O << "\n";
  }

  /// EmitDebugPubNames - Emit visible names into a debug pubnames section.
  ///
  void EmitDebugPubNames() {
    // Start the dwarf pubnames section.
    Asm->SwitchToDataSection(TAI->getDwarfPubNamesSection());
      
    // Process each compile unit.
    for (unsigned i = 0, N = CompileUnits.size(); i < N; ++i) {
      CompileUnit *Unit = CompileUnits[i];
      
      if (Unit->hasContent()) {
        EmitDifference("pubnames_end", Unit->getID(),
                       "pubnames_begin", Unit->getID());
        EOL("Length of Public Names Info");
        
        EmitLabel("pubnames_begin", Unit->getID());
        
        EmitInt16(DWARF_VERSION); EOL("DWARF Version");
        
        EmitDifference("info_begin", Unit->getID(), "section_info", 0);
        EOL("Offset of Compilation Unit Info");

        EmitDifference("info_end", Unit->getID(), "info_begin", Unit->getID());
        EOL("Compilation Unit Length");
        
        std::map<std::string, DIE *> &Globals = Unit->getGlobals();
        
        for (std::map<std::string, DIE *>::iterator GI = Globals.begin(),
                                                    GE = Globals.end();
             GI != GE; ++GI) {
          const std::string &Name = GI->first;
          DIE * Entity = GI->second;
          
          EmitInt32(Entity->getOffset()); EOL("DIE offset");
          EmitString(Name); EOL("External Name");
        }
      
        EmitInt32(0); EOL("End Mark");
        EmitLabel("pubnames_end", Unit->getID());
      
        O << "\n";
      }
    }
  }

  /// EmitDebugStr - Emit visible names into a debug str section.
  ///
  void 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];
        EmitString(String); O << "\n";
      }
    
      O << "\n";
    }
  }

  /// EmitDebugLoc - Emit visible names into a debug loc section.
  ///
  void EmitDebugLoc() {
    // Start the dwarf loc section.
    Asm->SwitchToDataSection(TAI->getDwarfLocSection());
    
    O << "\n";
  }

  /// EmitDebugARanges - Emit visible names into a debug aranges section.
  ///
  void EmitDebugARanges() {
    // Start the dwarf aranges section.
    Asm->SwitchToDataSection(TAI->getDwarfARangesSection());
    
    // FIXME - Mock up
  #if 0
    // Process each compile unit.
    for (unsigned i = 0, N = CompileUnits.size(); i < N; ++i) {
      CompileUnit *Unit = CompileUnits[i];
      
      if (Unit->hasContent()) {
        // Don't include size of length
        EmitInt32(0x1c); EOL("Length of Address Ranges Info");
        
        EmitInt16(DWARF_VERSION); EOL("Dwarf Version");
        
        EmitReference("info_begin", Unit->getID());
        EOL("Offset of Compilation Unit Info");

        EmitInt8(TAI->getAddressSize()); EOL("Size of Address");

        EmitInt8(0); EOL("Size of Segment Descriptor");

        EmitInt16(0);  EOL("Pad (1)");
        EmitInt16(0);  EOL("Pad (2)");

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

        EmitInt32(0); EOL("EOM (1)");
        EmitInt32(0); EOL("EOM (2)");
        
        O << "\n";
      }
    }
  #endif
  }

  /// EmitDebugRanges - Emit visible names into a debug ranges section.
  ///
  void EmitDebugRanges() {
    // Start the dwarf ranges section.
    Asm->SwitchToDataSection(TAI->getDwarfRangesSection());
    
    O << "\n";
  }

  /// EmitDebugMacInfo - Emit visible names into a debug macinfo section.
  ///
  void EmitDebugMacInfo() {
    // Start the dwarf macinfo section.
    Asm->SwitchToDataSection(TAI->getDwarfMacInfoSection());
    
    O << "\n";
  }

  /// ConstructCompileUnitDIEs - Create a compile unit DIE for each source and
  /// header file.
  void ConstructCompileUnitDIEs() {
    const UniqueVector<CompileUnitDesc *> CUW = DebugInfo->getCompileUnits();
    
    for (unsigned i = 1, N = CUW.size(); i <= N; ++i) {
      unsigned ID = DebugInfo->RecordSource(CUW[i]);
      CompileUnit *Unit = NewCompileUnit(CUW[i], ID);
      CompileUnits.push_back(Unit);
    }
  }

  /// ConstructGlobalDIEs - Create DIEs for each of the externally visible
  /// global variables.
  void ConstructGlobalDIEs() {
    std::vector<GlobalVariableDesc *> GlobalVariables =
        DebugInfo->getAnchoredDescriptors<GlobalVariableDesc>(*M);
    
    for (unsigned i = 0, N = GlobalVariables.size(); i < N; ++i) {
      GlobalVariableDesc *GVD = GlobalVariables[i];
      NewGlobalVariable(GVD);
    }
  }

  /// ConstructSubprogramDIEs - Create DIEs for each of the externally visible
  /// subprograms.
  void ConstructSubprogramDIEs() {
    std::vector<SubprogramDesc *> Subprograms =
        DebugInfo->getAnchoredDescriptors<SubprogramDesc>(*M);
    
    for (unsigned i = 0, N = Subprograms.size(); i < N; ++i) {
      SubprogramDesc *SPD = Subprograms[i];
      NewSubprogram(SPD);
    }
  }

  /// ShouldEmitDwarf - Returns true if Dwarf declarations should be made.
  ///
  bool ShouldEmitDwarf() const { return shouldEmit; }

public:
  //===--------------------------------------------------------------------===//
  // Main entry points.
  //
  Dwarf(std::ostream &OS, AsmPrinter *A, const TargetAsmInfo *T)
  : O(OS)
  , Asm(A)
  , TAI(T)
  , TD(Asm->TM.getTargetData())
  , RI(Asm->TM.getRegisterInfo())
  , M(NULL)
  , MF(NULL)
  , DebugInfo(NULL)
  , didInitial(false)
  , shouldEmit(false)
  , SubprogramCount(0)
  , CompileUnits()
  , AbbreviationsSet(InitAbbreviationsSetSize)
  , Abbreviations()
  , ValuesSet(InitValuesSetSize)
  , Values()
  , StringPool()
  , DescToUnitMap()
  , SectionMap()
  , SectionSourceLines()
  {
  }
  virtual ~Dwarf() {
    for (unsigned i = 0, N = CompileUnits.size(); i < N; ++i)
      delete CompileUnits[i];
    for (unsigned j = 0, M = Values.size(); j < M; ++j)
      delete Values[j];
  }

  // Accessors.
  //
  const TargetAsmInfo *getTargetAsmInfo() const { return TAI; }
  
  /// SetDebugInfo - Set DebugInfo when it's known that pass manager has
  /// created it.  Set by the target AsmPrinter.
  void SetDebugInfo(MachineDebugInfo *DI) {
    // Make sure initial declarations are made.
    if (!DebugInfo && DI->hasInfo()) {
      DebugInfo = DI;
      shouldEmit = true;
      
      // Emit initial sections
      EmitInitial();
    
      // Create all the compile unit DIEs.
      ConstructCompileUnitDIEs();
      
      // Create DIEs for each of the externally visible global variables.
      ConstructGlobalDIEs();

      // Create DIEs for each of the externally visible subprograms.
      ConstructSubprogramDIEs();
      
      // Prime section data.
      SectionMap.insert(TAI->getTextSection());
    }
  }

  /// BeginModule - Emit all Dwarf sections that should come prior to the
  /// content.
  void BeginModule(Module *M) {
    this->M = M;
    
    if (!ShouldEmitDwarf()) return;
    EOL("Dwarf Begin Module");
  }

  /// EndModule - Emit all Dwarf sections that should come after the content.
  ///
  void EndModule() {
    if (!ShouldEmitDwarf()) return;
    EOL("Dwarf End Module");
    
    // Standard sections final addresses.
    Asm->SwitchToTextSection(TAI->getTextSection());
    EmitLabel("text_end", 0);
    Asm->SwitchToDataSection(TAI->getDataSection());
    EmitLabel("data_end", 0);
    
    // End text sections.
    for (unsigned i = 1, N = SectionMap.size(); i <= N; ++i) {
      Asm->SwitchToTextSection(SectionMap[i].c_str());
      EmitLabel("section_end", 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();
  }

  /// BeginFunction - Gather pre-function debug information.  Assumes being 
  /// emitted immediately after the function entry point.
  void BeginFunction(MachineFunction *MF) {
    this->MF = MF;
    
    if (!ShouldEmitDwarf()) return;
    EOL("Dwarf Begin Function");

    // Begin accumulating function debug information.
    DebugInfo->BeginFunction(MF);
    
    // Assumes in correct section after the entry point.
    EmitLabel("func_begin", ++SubprogramCount);
  }

  /// EndFunction - Gather and emit post-function debug information.
  ///
  void EndFunction() {
    if (!ShouldEmitDwarf()) return;
    EOL("Dwarf End Function");
    
    // Define end label for subprogram.
    EmitLabel("func_end", SubprogramCount);
      
    // Get function line info.
    const std::vector<SourceLineInfo> &LineInfos = DebugInfo->getSourceLines();

    if (!LineInfos.empty()) {
      // Get section line info.
      unsigned ID = SectionMap.insert(Asm->CurrentSection);
      if (SectionSourceLines.size() < ID) SectionSourceLines.resize(ID);
      std::vector<SourceLineInfo> &SectionLineInfos = SectionSourceLines[ID-1];
      // Append the function info to section info.
      SectionLineInfos.insert(SectionLineInfos.end(),
                              LineInfos.begin(), LineInfos.end());
    }
    
    // Construct scopes for subprogram.
    ConstructRootScope(DebugInfo->getRootScope());
    
    // Emit function frame information.
    EmitFunctionDebugFrame();
    
    // Reset the line numbers for the next function.
    DebugInfo->ClearLineInfo();

    // Clear function debug information.
    DebugInfo->EndFunction();
  }
};

} // End of namespace llvm

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

/// Emit - Print the abbreviation using the specified Dwarf writer.
///
void DIEAbbrev::Emit(const Dwarf &DW) const {
  // Emit its Dwarf tag type.
  DW.EmitULEB128Bytes(Tag);
  DW.EOL(TagString(Tag));
  
  // Emit whether it has children DIEs.
  DW.EmitULEB128Bytes(ChildrenFlag);
  DW.EOL(ChildrenString(ChildrenFlag));
  
  // For each attribute description.
  for (unsigned i = 0, N = Data.size(); i < N; ++i) {
    const DIEAbbrevData &AttrData = Data[i];
    
    // Emit attribute type.
    DW.EmitULEB128Bytes(AttrData.getAttribute());
    DW.EOL(AttributeString(AttrData.getAttribute()));
    
    // Emit form type.
    DW.EmitULEB128Bytes(AttrData.getForm());
    DW.EOL(FormEncodingString(AttrData.getForm()));
  }

  // Mark end of abbreviation.
  DW.EmitULEB128Bytes(0); DW.EOL("EOM(1)");
  DW.EmitULEB128Bytes(0); DW.EOL("EOM(2)");
}

#ifndef NDEBUG
void DIEAbbrev::print(std::ostream &O) {
  O << "Abbreviation @"
    << std::hex << (intptr_t)this << std::dec
    << "  "
    << TagString(Tag)
    << " "
    << ChildrenString(ChildrenFlag)
    << "\n";
  
  for (unsigned i = 0, N = Data.size(); i < N; ++i) {
    O << "  "
      << AttributeString(Data[i].getAttribute())
      << "  "
      << FormEncodingString(Data[i].getForm())
      << "\n";
  }
}
void DIEAbbrev::dump() { print(std::cerr); }
#endif

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

#ifndef NDEBUG
void DIEValue::dump() {
  print(std::cerr);
}
#endif

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

/// EmitValue - Emit integer of appropriate size.
///
void DIEInteger::EmitValue(const Dwarf &DW, unsigned Form) const {
  switch (Form) {
  case DW_FORM_flag:  // Fall thru
  case DW_FORM_ref1:  // Fall thru
  case DW_FORM_data1: DW.EmitInt8(Integer);         break;
  case DW_FORM_ref2:  // Fall thru
  case DW_FORM_data2: DW.EmitInt16(Integer);        break;
  case DW_FORM_ref4:  // Fall thru
  case DW_FORM_data4: DW.EmitInt32(Integer);        break;
  case DW_FORM_ref8:  // Fall thru
  case DW_FORM_data8: DW.EmitInt64(Integer);        break;
  case DW_FORM_udata: DW.EmitULEB128Bytes(Integer); break;
  case DW_FORM_sdata: DW.EmitSLEB128Bytes(Integer); break;
  default: assert(0 && "DIE Value form not supported yet"); break;
  }
}

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

/// EmitValue - Emit string value.
///
void DIEString::EmitValue(const Dwarf &DW, unsigned Form) const {
  DW.EmitString(String);
}

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

/// EmitValue - Emit label value.
///
void DIEDwarfLabel::EmitValue(const Dwarf &DW, unsigned Form) const {
  DW.EmitReference(Label);
}

/// SizeOf - Determine size of label value in bytes.
///
unsigned DIEDwarfLabel::SizeOf(const Dwarf &DW, unsigned Form) const {
  return DW.getTargetAsmInfo()->getAddressSize();
}

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

/// EmitValue - Emit label value.
///
void DIEObjectLabel::EmitValue(const Dwarf &DW, unsigned Form) const {
  DW.EmitReference(Label);
}

/// SizeOf - Determine size of label value in bytes.
///
unsigned DIEObjectLabel::SizeOf(const Dwarf &DW, unsigned Form) const {
  return DW.getTargetAsmInfo()->getAddressSize();
}
    
//===----------------------------------------------------------------------===//

/// EmitValue - Emit delta value.
///
void DIEDelta::EmitValue(const Dwarf &DW, unsigned Form) const {
  DW.EmitDifference(LabelHi, LabelLo);
}

/// SizeOf - Determine size of delta value in bytes.
///
unsigned DIEDelta::SizeOf(const Dwarf &DW, unsigned Form) const {
  return DW.getTargetAsmInfo()->getAddressSize();
}

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

/// EmitValue - Emit debug information entry offset.
///
void DIEntry::EmitValue(const Dwarf &DW, unsigned Form) const {
  DW.EmitInt32(Entry->getOffset());
}
    
//===----------------------------------------------------------------------===//

/// ComputeSize - calculate the size of the block.
///
unsigned DIEBlock::ComputeSize(Dwarf &DW) {
  if (!Size) {
    const std::vector<DIEAbbrevData> &AbbrevData = Abbrev.getData();
    
    for (unsigned i = 0, N = Values.size(); i < N; ++i) {
      Size += Values[i]->SizeOf(DW, AbbrevData[i].getForm());
    }
  }
  return Size;
}

/// EmitValue - Emit block data.
///
void DIEBlock::EmitValue(const Dwarf &DW, unsigned Form) const {
  switch (Form) {
  case DW_FORM_block1: DW.EmitInt8(Size);         break;
  case DW_FORM_block2: DW.EmitInt16(Size);        break;
  case DW_FORM_block4: DW.EmitInt32(Size);        break;
  case DW_FORM_block:  DW.EmitULEB128Bytes(Size); break;
  default: assert(0 && "Improper form for block"); break;
  }
  
  const std::vector<DIEAbbrevData> &AbbrevData = Abbrev.getData();

  for (unsigned i = 0, N = Values.size(); i < N; ++i) {
    DW.EOL("");
    Values[i]->EmitValue(DW, AbbrevData[i].getForm());
  }
}

/// SizeOf - Determine size of block data in bytes.
///
unsigned DIEBlock::SizeOf(const Dwarf &DW, unsigned Form) const {
  switch (Form) {
  case DW_FORM_block1: return Size + sizeof(int8_t);
  case DW_FORM_block2: return Size + sizeof(int16_t);
  case DW_FORM_block4: return Size + sizeof(int32_t);
  case DW_FORM_block: return Size + SizeULEB128(Size);
  default: assert(0 && "Improper form for block"); break;
  }
  return 0;
}

//===----------------------------------------------------------------------===//
/// DIE Implementation

DIE::~DIE() {
  for (unsigned i = 0, N = Children.size(); i < N; ++i)
    delete Children[i];
}
  
/// AddSiblingOffset - Add a sibling offset field to the front of the DIE.
///
void DIE::AddSiblingOffset() {
  DIEInteger *DI = new DIEInteger(0);
  Values.insert(Values.begin(), DI);
  Abbrev.AddFirstAttribute(DW_AT_sibling, DW_FORM_ref4);
}

/// Profile - Used to gather unique data for the value folding set.
///
void DIE::Profile(FoldingSetNodeID &ID) {
  Abbrev.Profile(ID);
  
  for (unsigned i = 0, N = Children.size(); i < N; ++i)
    ID.AddPointer(Children[i]);

  for (unsigned j = 0, M = Values.size(); j < M; ++j)
    ID.AddPointer(Values[j]);
}

#ifndef NDEBUG
void DIE::print(std::ostream &O, unsigned IncIndent) {
  static unsigned IndentCount = 0;
  IndentCount += IncIndent;
  const std::string Indent(IndentCount, ' ');
  bool isBlock = Abbrev.getTag() == 0;
  
  if (!isBlock) {
    O << Indent
      << "Die: "
      << "0x" << std::hex << (intptr_t)this << std::dec
      << ", Offset: " << Offset
      << ", Size: " << Size
      << "\n"; 
    
    O << Indent
      << TagString(Abbrev.getTag())
      << " "
      << ChildrenString(Abbrev.getChildrenFlag());
  } else {
    O << "Size: " << Size;
  }
  O << "\n";

  const std::vector<DIEAbbrevData> &Data = Abbrev.getData();
  
  IndentCount += 2;
  for (unsigned i = 0, N = Data.size(); i < N; ++i) {
    O << Indent;
    if (!isBlock) {
      O << AttributeString(Data[i].getAttribute());
    } else {
      O << "Blk[" << i << "]";
    }
    O <<  "  "
      << FormEncodingString(Data[i].getForm())
      << " ";
    Values[i]->print(O);
    O << "\n";
  }
  IndentCount -= 2;

  for (unsigned j = 0, M = Children.size(); j < M; ++j) {
    Children[j]->print(O, 4);
  }
  
  if (!isBlock) O << "\n";
  IndentCount -= IncIndent;
}

void DIE::dump() {
  print(std::cerr);
}
#endif

//===----------------------------------------------------------------------===//
/// DwarfWriter Implementation
///

DwarfWriter::DwarfWriter(std::ostream &OS, AsmPrinter *A,
                         const TargetAsmInfo *T) {
  DW = new Dwarf(OS, A, T);
}

DwarfWriter::~DwarfWriter() {
  delete DW;
}

/// SetDebugInfo - Set DebugInfo when it's known that pass manager has
/// created it.  Set by the target AsmPrinter.
void DwarfWriter::SetDebugInfo(MachineDebugInfo *DI) {
  DW->SetDebugInfo(DI);
}

/// BeginModule - Emit all Dwarf sections that should come prior to the
/// content.
void DwarfWriter::BeginModule(Module *M) {
  DW->BeginModule(M);
}

/// EndModule - Emit all Dwarf sections that should come after the content.
///
void DwarfWriter::EndModule() {
  DW->EndModule();
}

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

/// EndFunction - Gather and emit post-function debug information.
///
void DwarfWriter::EndFunction() {
  DW->EndFunction();
}