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/StringExtras.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/Mangler.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetFrameInfo.h"

#include <iostream>

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 {

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

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

public:
  CompileUnit(CompileUnitDesc *CUD, unsigned I, DIE *D)
  : Desc(CUD)
  , ID(I)
  , Die(D)
  , Globals()
  , DescToDieMap()
  {}
  
  ~CompileUnit();
  
  // 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;
  
  /// AddGlobal - Add a new global entity to the compile unit.
  ///
  void AddGlobal(const std::string &Name, DIE *Die);
  
  /// getDieMapSlotFor - Returns the debug information entry map slot for the
  /// specified debug descriptor.
  DIE *&getDieMapSlotFor(DebugInfoDesc *DD) {
    return DescToDieMap[DD];
  }
};

//===----------------------------------------------------------------------===//
// DIEAbbrevData - Dwarf abbreviation data, describes the one attribute of a
// Dwarf abbreviation.
class DIEAbbrevData {
private:
  unsigned Attribute;                 // Dwarf attribute code.
  unsigned Form;                      // Dwarf form code.
  
public:
  DIEAbbrevData(unsigned A, unsigned F)
  : Attribute(A)
  , Form(F)
  {}
  
  // Accessors.
  unsigned getAttribute() const { return Attribute; }
  unsigned getForm()      const { return Form; }
  
  /// operator== - Used by DIEAbbrev to locate entry.
  ///
  bool operator==(const DIEAbbrevData &DAD) const {
    return Attribute == DAD.Attribute && Form == DAD.Form;
  }

  /// operator!= - Used by DIEAbbrev to locate entry.
  ///
  bool operator!=(const DIEAbbrevData &DAD) const {
    return Attribute != DAD.Attribute || Form != DAD.Form;
  }
  
  /// operator< - Used by DIEAbbrev to locate entry.
  ///
  bool operator<(const DIEAbbrevData &DAD) const {
    return Attribute < DAD.Attribute ||
          (Attribute == DAD.Attribute && Form < DAD.Form);
  }
};

//===----------------------------------------------------------------------===//
// DIEAbbrev - Dwarf abbreviation, describes the organization of a debug
// information object.
class DIEAbbrev {
private:
  unsigned Tag;                       // Dwarf tag code.
  unsigned ChildrenFlag;              // Dwarf children flag.
  std::vector<DIEAbbrevData> Data;    // Raw data bytes for abbreviation.

public:

  DIEAbbrev(unsigned T, unsigned C)
  : Tag(T)
  , ChildrenFlag(C)
  , Data()
  {}
  ~DIEAbbrev() {}
  
  // Accessors.
  unsigned getTag()                           const { return Tag; }
  unsigned getChildrenFlag()                  const { return ChildrenFlag; }
  const std::vector<DIEAbbrevData> &getData() const { return Data; }
  void setChildrenFlag(unsigned CF)                 { ChildrenFlag = CF; }

  /// operator== - Used by UniqueVector to locate entry.
  ///
  bool operator==(const DIEAbbrev &DA) const;

  /// operator< - Used by UniqueVector to locate entry.
  ///
  bool operator<(const DIEAbbrev &DA) const;

  /// 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));
  }
  
  /// Emit - Print the abbreviation using the specified Dwarf writer.
  ///
  void Emit(const DwarfWriter &DW) const; 
      
#ifndef NDEBUG
  void print(std::ostream &O);
  void dump();
#endif
};

//===----------------------------------------------------------------------===//
// DIEValue - A debug information entry value.
//
class DIEValue {
public:
  enum {
    isInteger,
    isString,
    isLabel,
    isAsIsLabel,
    isDelta,
    isEntry,
    isBlock
  };
  
  unsigned Type;                      // Type of the value
  
  DIEValue(unsigned T) : Type(T) {}
  virtual ~DIEValue() {}
  
  // Implement isa/cast/dyncast.
  static bool classof(const DIEValue *) { return true; }
  
  /// EmitValue - Emit value via the Dwarf writer.
  ///
  virtual void EmitValue(const DwarfWriter &DW, unsigned Form) const = 0;
  
  /// SizeOf - Return the size of a value in bytes.
  ///
  virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const = 0;
};

//===----------------------------------------------------------------------===//
// 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.
  ///
  unsigned BestForm(bool IsSigned);

  /// EmitValue - Emit integer of appropriate size.
  ///
  virtual void EmitValue(const DwarfWriter &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of integer value in bytes.
  ///
  virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
};

//===----------------------------------------------------------------------===//
// DIEString - A string value DIE.
// 
struct DIEString : public DIEValue {
  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 DwarfWriter &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of string value in bytes.
  ///
  virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
};

//===----------------------------------------------------------------------===//
// DIEDwarfLabel - A Dwarf internal label expression DIE.
//
struct DIEDwarfLabel : public DIEValue {
  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 DwarfWriter &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of label value in bytes.
  ///
  virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
};


//===----------------------------------------------------------------------===//
// DIEObjectLabel - A label to an object in code or data.
//
struct DIEObjectLabel : public DIEValue {
  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 DwarfWriter &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of label value in bytes.
  ///
  virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
};

//===----------------------------------------------------------------------===//
// DIEDelta - A simple label difference DIE.
// 
struct DIEDelta : public DIEValue {
  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 DwarfWriter &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of delta value in bytes.
  ///
  virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
};

//===----------------------------------------------------------------------===//
// DIEntry - A pointer to a debug information entry.
// 
struct DIEntry : public DIEValue {
  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 DwarfWriter &DW, unsigned Form) const;
  
  /// SizeOf - Determine size of debug information entry in bytes.
  ///
  virtual unsigned SizeOf(const DwarfWriter &DW, unsigned Form) const;
};

//===----------------------------------------------------------------------===//
// DIEBlock - A block of values.  Primarily used for location expressions.
//
struct DIEBlock : public DIEValue {
  unsigned Size;                        // Size in bytes excluding size header.
  std::vector<unsigned> Forms;          // Data forms.
  std::vector<DIEValue *> Values;       // Block values.
  
  DIEBlock()
  : DIEValue(isBlock)
  , Size(0)
  , Forms()
  , Values()
  {}
  ~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(DwarfWriter &DW);
  
  /// BestForm - Choose the best form for data.
  ///
  unsigned BestForm();

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

  /// AddUInt - Add an unsigned integer value.
  ///
  void AddUInt(unsigned Form, uint64_t Integer);

  /// AddSInt - Add an signed integer value.
  ///
  void AddSInt(unsigned Form, int64_t Integer);
      
  /// AddString - Add a std::string value.
  ///
  void AddString(unsigned Form, const std::string &String);
      
  /// AddLabel - Add a Dwarf label value.
  ///
  void AddLabel(unsigned Form, const DWLabel &Label);
      
  /// AddObjectLabel - Add a non-Dwarf label value.
  ///
  void AddObjectLabel(unsigned Form, const std::string &Label);
      
  /// AddDelta - Add a label delta value.
  ///
  void AddDelta(unsigned Form, const DWLabel &Hi, const DWLabel &Lo);
      
  /// AddDIEntry - Add a DIE value.
  ///
  void AddDIEntry(unsigned Form, DIE *Entry);

};

//===----------------------------------------------------------------------===//
// DIE - A structured debug information entry.  Has an abbreviation which
// describes it's organization.
class DIE {
private:
  DIEAbbrev *Abbrev;                    // Temporary buffer for abbreviation.
  unsigned AbbrevID;                    // Decribing abbreviation ID.
  unsigned Offset;                      // Offset in debug info section.
  unsigned Size;                        // Size of instance + children.
  std::vector<DIE *> Children;          // Children DIEs.
  std::vector<DIEValue *> Values;       // Attributes values.
  
public:
  DIE(unsigned Tag);
  ~DIE();
  
  // Accessors.
  unsigned   getAbbrevID()                   const { return AbbrevID; }
  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 setOffset(unsigned O)                 { Offset = O; }
  void setSize(unsigned S)                   { Size = S; }
  
  /// 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();

  /// AddUInt - Add an unsigned integer attribute data and value.
  ///
  void AddUInt(unsigned Attribute, unsigned Form, uint64_t Integer);

  /// AddSInt - Add an signed integer attribute data and value.
  ///
  void AddSInt(unsigned Attribute, unsigned Form, int64_t Integer);
      
  /// AddString - Add a std::string attribute data and value.
  ///
  void AddString(unsigned Attribute, unsigned Form,
                 const std::string &String);
      
  /// AddLabel - Add a Dwarf label attribute data and value.
  ///
  void AddLabel(unsigned Attribute, unsigned Form, const DWLabel &Label);
      
  /// AddObjectLabel - Add a non-Dwarf label attribute data and value.
  ///
  void AddObjectLabel(unsigned Attribute, unsigned Form,
                      const std::string &Label);
      
  /// AddDelta - Add a label delta attribute data and value.
  ///
  void AddDelta(unsigned Attribute, unsigned Form,
                const DWLabel &Hi, const DWLabel &Lo);
      
  /// AddDIEntry - Add a DIE attribute data and value.
  ///
  void AddDIEntry(unsigned Attribute, unsigned Form, DIE *Entry);

  /// AddBlock - Add block data.
  ///
  void AddBlock(unsigned Attribute, unsigned Form, DIEBlock *Block);

  /// Complete - Indicate that all attributes have been added and
  /// ready to get an abbreviation ID.
  ///
  void Complete(DwarfWriter &DW);
  
  /// AddChild - Add a child to the DIE.
  void AddChild(DIE *Child);
};

} // End of namespace llvm

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

CompileUnit::~CompileUnit() {
  delete Die;
}

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

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

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

/// operator== - Used by UniqueVector to locate entry.
///
bool DIEAbbrev::operator==(const DIEAbbrev &DA) const {
  if (Tag != DA.Tag) return false;
  if (ChildrenFlag != DA.ChildrenFlag) return false;
  if (Data.size() != DA.Data.size()) return false;
  
  for (unsigned i = 0, N = Data.size(); i < N; ++i) {
    if (Data[i] != DA.Data[i]) return false;
  }
  
  return true;
}

/// operator< - Used by UniqueVector to locate entry.
///
bool DIEAbbrev::operator<(const DIEAbbrev &DA) const {
  if (Tag != DA.Tag) return Tag < DA.Tag;
  if (ChildrenFlag != DA.ChildrenFlag) return ChildrenFlag < DA.ChildrenFlag;
  if (Data.size() != DA.Data.size()) return Data.size() < DA.Data.size();
  
  for (unsigned i = 0, N = Data.size(); i < N; ++i) {
    if (Data[i] != DA.Data[i]) return Data[i] < DA.Data[i];
  }
  
  return false;
}
    
/// Emit - Print the abbreviation using the specified Dwarf writer.
///
void DIEAbbrev::Emit(const DwarfWriter &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

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

/// BestForm - Choose the best form for integer.
///
unsigned DIEInteger::BestForm(bool IsSigned) {
  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.
///
void DIEInteger::EmitValue(const DwarfWriter &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;
  }
}

/// SizeOf - Determine size of integer value in bytes.
///
unsigned DIEInteger::SizeOf(const DwarfWriter &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 DW.SizeULEB128(Integer);
  case DW_FORM_sdata: return DW.SizeSLEB128(Integer);
  default: assert(0 && "DIE Value form not supported yet"); break;
  }
  return 0;
}

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

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

/// SizeOf - Determine size of string value in bytes.
///
unsigned DIEString::SizeOf(const DwarfWriter &DW, unsigned Form) const {
  return String.size() + sizeof(char); // sizeof('\0');
}

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

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

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

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

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

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

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

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

/// SizeOf - Determine size of debug information entry value in bytes.
///
unsigned DIEntry::SizeOf(const DwarfWriter &DW, unsigned Form) const {
  return sizeof(int32_t);
}
    
//===----------------------------------------------------------------------===//

DIEBlock::~DIEBlock() {
  for (unsigned i = 0, N = Values.size(); i < N; ++i) {
    delete Values[i];
  }
}

/// ComputeSize - calculate the size of the block.
///
unsigned DIEBlock::ComputeSize(DwarfWriter &DW) {
  Size = 0;
  for (unsigned i = 0, N = Values.size(); i < N; ++i) {
    Size += Values[i]->SizeOf(DW, Forms[i]);
  }
  return Size;
}

/// BestForm - Choose the best form for data.
///
unsigned DIEBlock::BestForm() {
  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.
///
void DIEBlock::EmitValue(const DwarfWriter &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;
  }
  for (unsigned i = 0, N = Values.size(); i < N; ++i) {
    DW.EOL("");
    Values[i]->EmitValue(DW, Forms[i]);
  }
}

/// SizeOf - Determine size of block data in bytes.
///
unsigned DIEBlock::SizeOf(const DwarfWriter &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 + DW.SizeULEB128(Size);
  default: assert(0 && "Improper form for block"); break;
  }
  return 0;
}

/// AddUInt - Add an unsigned integer value.
///
void DIEBlock::AddUInt(unsigned Form, uint64_t Integer) {
  DIEInteger *DI = new DIEInteger(Integer);
  Values.push_back(DI);
  if (Form == 0) Form = DI->BestForm(false);
  Forms.push_back(Form);
}

/// AddSInt - Add an signed integer value.
///
void DIEBlock::AddSInt(unsigned Form, int64_t Integer) {
  DIEInteger *DI = new DIEInteger(Integer);
  Values.push_back(DI);
  if (Form == 0) Form = DI->BestForm(true);
  Forms.push_back(Form);
}
    
/// AddString - Add a std::string value.
///
void DIEBlock::AddString(unsigned Form, const std::string &String) {
  Values.push_back(new DIEString(String));
  Forms.push_back(Form);
}
    
/// AddLabel - Add a Dwarf label value.
///
void DIEBlock::AddLabel(unsigned Form, const DWLabel &Label) {
  Values.push_back(new DIEDwarfLabel(Label));
  Forms.push_back(Form);
}
    
/// AddObjectLabel - Add a non-Dwarf label value.
///
void DIEBlock::AddObjectLabel(unsigned Form, const std::string &Label) {
  Values.push_back(new DIEObjectLabel(Label));
  Forms.push_back(Form);
}
    
/// AddDelta - Add a label delta value.
///
void DIEBlock::AddDelta(unsigned Form, const DWLabel &Hi, const DWLabel &Lo) {
  Values.push_back(new DIEDelta(Hi, Lo));
  Forms.push_back(Form);
}
    
/// AddDIEntry - Add a DIE value.
///
void DIEBlock::AddDIEntry(unsigned Form, DIE *Entry) {
  Values.push_back(new DIEntry(Entry));
  Forms.push_back(Form);
}

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

DIE::DIE(unsigned Tag)
: Abbrev(new DIEAbbrev(Tag, DW_CHILDREN_no))
, AbbrevID(0)
, Offset(0)
, Size(0)
, Children()
, Values()
{}

DIE::~DIE() {
  if (Abbrev) delete Abbrev;
  
  for (unsigned i = 0, N = Children.size(); i < N; ++i) {
    delete Children[i];
  }

  for (unsigned j = 0, M = Values.size(); j < M; ++j) {
    delete Values[j];
  }
}
    
/// 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);
}

/// AddUInt - Add an unsigned integer attribute data and value.
///
void DIE::AddUInt(unsigned Attribute, unsigned Form, uint64_t Integer) {
  DIEInteger *DI = new DIEInteger(Integer);
  Values.push_back(DI);
  if (!Form) Form = DI->BestForm(false);
  Abbrev->AddAttribute(Attribute, Form);
}
    
/// AddSInt - Add an signed integer attribute data and value.
///
void DIE::AddSInt(unsigned Attribute, unsigned Form, int64_t Integer) {
  DIEInteger *DI = new DIEInteger(Integer);
  Values.push_back(DI);
  if (!Form) Form = DI->BestForm(true);
  Abbrev->AddAttribute(Attribute, Form);
}
    
/// AddString - Add a std::string attribute data and value.
///
void DIE::AddString(unsigned Attribute, unsigned Form,
                    const std::string &String) {
  Values.push_back(new DIEString(String));
  Abbrev->AddAttribute(Attribute, Form);
}
    
/// AddLabel - Add a Dwarf label attribute data and value.
///
void DIE::AddLabel(unsigned Attribute, unsigned Form,
                   const DWLabel &Label) {
  Values.push_back(new DIEDwarfLabel(Label));
  Abbrev->AddAttribute(Attribute, Form);
}
    
/// AddObjectLabel - Add an non-Dwarf label attribute data and value.
///
void DIE::AddObjectLabel(unsigned Attribute, unsigned Form,
                         const std::string &Label) {
  Values.push_back(new DIEObjectLabel(Label));
  Abbrev->AddAttribute(Attribute, Form);
}
    
/// AddDelta - Add a label delta attribute data and value.
///
void DIE::AddDelta(unsigned Attribute, unsigned Form,
                   const DWLabel &Hi, const DWLabel &Lo) {
  Values.push_back(new DIEDelta(Hi, Lo));
  Abbrev->AddAttribute(Attribute, Form);
}
    
/// AddDIEntry - Add a DIE attribute data and value.
///
void DIE::AddDIEntry(unsigned Attribute, unsigned Form, DIE *Entry) {
  Values.push_back(new DIEntry(Entry));
  Abbrev->AddAttribute(Attribute, Form);
}

/// AddBlock - Add block data.
///
void DIE::AddBlock(unsigned Attribute, unsigned Form, DIEBlock *Block) {
  assert(Block->Size && "Block size has not been computed");
  Values.push_back(Block);
  if (!Form) Form = Block->BestForm();
  Abbrev->AddAttribute(Attribute, Form);
}

/// Complete - Indicate that all attributes have been added and ready to get an
/// abbreviation ID.
void DIE::Complete(DwarfWriter &DW) {
  AbbrevID = DW.NewAbbreviation(Abbrev);
  delete Abbrev;
  Abbrev = NULL;
}

/// AddChild - Add a child to the DIE.
///
void DIE::AddChild(DIE *Child) {
  assert(Abbrev && "Adding children without an abbreviation");
  Abbrev->setChildrenFlag(DW_CHILDREN_yes);
  Children.push_back(Child);
}

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

/// DWContext

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

/// PrintHex - Print a value as a hexidecimal value.
///
void DwarfWriter::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 DwarfWriter::EOL(const std::string &Comment) const {
  if (DwarfVerbose && !Comment.empty()) {
    O << "\t"
      << Asm->CommentString
      << " "
      << Comment;
  }
  O << "\n";
}

/// EmitAlign - Print a align directive.
///
void DwarfWriter::EmitAlign(unsigned Alignment) const {
  O << Asm->AlignDirective << Alignment << "\n";
}

/// EmitULEB128Bytes - Emit an assembler byte data directive to compose an
/// unsigned leb128 value.
void DwarfWriter::EmitULEB128Bytes(unsigned Value) const {
  if (hasLEB128) {
    O << "\t.uleb128\t"
      << Value;
  } else {
    O << Asm->Data8bitsDirective;
    PrintULEB128(Value);
  }
}

/// EmitSLEB128Bytes - Emit an assembler byte data directive to compose a
/// signed leb128 value.
void DwarfWriter::EmitSLEB128Bytes(int Value) const {
  if (hasLEB128) {
    O << "\t.sleb128\t"
      << Value;
  } else {
    O << Asm->Data8bitsDirective;
    PrintSLEB128(Value);
  }
}

/// PrintULEB128 - Print a series of hexidecimal values (separated by commas)
/// representing an unsigned leb128 value.
void DwarfWriter::PrintULEB128(unsigned Value) const {
  do {
    unsigned Byte = Value & 0x7f;