DwarfDebug.cpp

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

  // Get an anonymous type for index type.
  DIE *IdxTy = ModuleCU->getIndexTyDie();
  if (!IdxTy) {
    // Construct an anonymous type for index type.
    IdxTy = new DIE(dwarf::DW_TAG_base_type);
    addUInt(IdxTy, dwarf::DW_AT_byte_size, 0, sizeof(int32_t));
    addUInt(IdxTy, dwarf::DW_AT_encoding, dwarf::DW_FORM_data1,
            dwarf::DW_ATE_signed);
    ModuleCU->addDie(IdxTy);
    ModuleCU->setIndexTyDie(IdxTy);
  }

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

/// constructEnumTypeDIE - Construct enum type DIE from DIEnumerator.
DIE *DwarfDebug::constructEnumTypeDIE(DIEnumerator *ETy) {
  DIE *Enumerator = new DIE(dwarf::DW_TAG_enumerator);
  StringRef Name = ETy->getName();
  addString(Enumerator, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
  int64_t Value = ETy->getEnumValue();
  addSInt(Enumerator, dwarf::DW_AT_const_value, dwarf::DW_FORM_sdata, Value);
  return Enumerator;
}

/// getRealLinkageName - If special LLVM prefix that is used to inform the asm 
/// printer to not emit usual symbol prefix before the symbol name is used then
/// return linkage name after skipping this special LLVM prefix.
static StringRef getRealLinkageName(StringRef LinkageName) {
  char One = '\1';
  if (LinkageName.startswith(StringRef(&One, 1)))
    return LinkageName.substr(1);
  return LinkageName;
}

/// createGlobalVariableDIE - Create new DIE using GV.
DIE *DwarfDebug::createGlobalVariableDIE(const DIGlobalVariable &GV) {
  // If the global variable was optmized out then no need to create debug info
  // entry.
  if (!GV.getGlobal()) return NULL;
  if (GV.getDisplayName().empty()) return NULL;

  DIE *GVDie = new DIE(dwarf::DW_TAG_variable);
  addString(GVDie, dwarf::DW_AT_name, dwarf::DW_FORM_string,
            GV.getDisplayName());

  StringRef LinkageName = GV.getLinkageName();
  if (!LinkageName.empty())
    addString(GVDie, dwarf::DW_AT_MIPS_linkage_name, dwarf::DW_FORM_string,
              getRealLinkageName(LinkageName));

  addType(GVDie, GV.getType());
  if (!GV.isLocalToUnit())
    addUInt(GVDie, dwarf::DW_AT_external, dwarf::DW_FORM_flag, 1);
  addSourceLine(GVDie, &GV);

  return GVDie;
}

/// createMemberDIE - Create new member DIE.
DIE *DwarfDebug::createMemberDIE(const DIDerivedType &DT) {
  DIE *MemberDie = new DIE(DT.getTag());
  StringRef Name = DT.getName();
  if (!Name.empty())
    addString(MemberDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
  
  addType(MemberDie, DT.getTypeDerivedFrom());

  addSourceLine(MemberDie, &DT);

  DIEBlock *MemLocationDie = new DIEBlock();
  addUInt(MemLocationDie, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_plus_uconst);

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

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

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

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

    // Here WD_AT_data_member_location points to the anonymous
    // field that includes this bit field.
    addUInt(MemLocationDie, 0, dwarf::DW_FORM_udata, FieldOffset >> 3);

  } else
    // This is not a bitfield.
    addUInt(MemLocationDie, 0, dwarf::DW_FORM_udata, DT.getOffsetInBits() >> 3);

  addBlock(MemberDie, dwarf::DW_AT_data_member_location, 0, MemLocationDie);

  if (DT.isProtected())
    addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
            dwarf::DW_ACCESS_protected);
  else if (DT.isPrivate())
    addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
            dwarf::DW_ACCESS_private);
  else if (DT.getTag() == dwarf::DW_TAG_inheritance)
    addUInt(MemberDie, dwarf::DW_AT_accessibility, dwarf::DW_FORM_flag,
            dwarf::DW_ACCESS_public);
  if (DT.isVirtual())
    addUInt(MemberDie, dwarf::DW_AT_virtuality, dwarf::DW_FORM_flag,
            dwarf::DW_VIRTUALITY_virtual);
  return MemberDie;
}

/// createSubprogramDIE - Create new DIE using SP.
DIE *DwarfDebug::createSubprogramDIE(const DISubprogram &SP, bool MakeDecl) {
  DIE *SPDie = ModuleCU->getDIE(SP.getNode());
  if (SPDie)
    return SPDie;

  SPDie = new DIE(dwarf::DW_TAG_subprogram);
  addString(SPDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, SP.getName());

  StringRef LinkageName = SP.getLinkageName();
  if (!LinkageName.empty())
    addString(SPDie, dwarf::DW_AT_MIPS_linkage_name, dwarf::DW_FORM_string,
              getRealLinkageName(LinkageName));

  addSourceLine(SPDie, &SP);

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

  // Add Return Type.
  DICompositeType SPTy = SP.getType();
  DIArray Args = SPTy.getTypeArray();
  unsigned SPTag = SPTy.getTag();

  if (Args.isNull() || SPTag != dwarf::DW_TAG_subroutine_type)
    addType(SPDie, SPTy);
  else
    addType(SPDie, DIType(Args.getElement(0).getNode()));

  unsigned VK = SP.getVirtuality();
  if (VK) {
    addUInt(SPDie, dwarf::DW_AT_virtuality, dwarf::DW_FORM_flag, VK);
    DIEBlock *Block = new DIEBlock();
    addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_constu);
    addUInt(Block, 0, dwarf::DW_FORM_data1, SP.getVirtualIndex());
    addBlock(SPDie, dwarf::DW_AT_vtable_elem_location, 0, Block);
    ContainingTypeMap.insert(std::make_pair(SPDie, WeakVH(SP.getContainingType().getNode())));
  }

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

    // Add arguments. Do not add arguments for subprogram definition. They will
    // be handled while processing variables.
    DICompositeType SPTy = SP.getType();
    DIArray Args = SPTy.getTypeArray();
    unsigned SPTag = SPTy.getTag();

    if (SPTag == dwarf::DW_TAG_subroutine_type)
      for (unsigned i = 1, N =  Args.getNumElements(); i < N; ++i) {
        DIE *Arg = new DIE(dwarf::DW_TAG_formal_parameter);
        addType(Arg, DIType(Args.getElement(i).getNode()));
        addUInt(Arg, dwarf::DW_AT_artificial, dwarf::DW_FORM_flag, 1); // ??
        SPDie->addChild(Arg);
      }
  }

  // DW_TAG_inlined_subroutine may refer to this DIE.
  ModuleCU->insertDIE(SP.getNode(), SPDie);
  return SPDie;
}

/// findCompileUnit - Get the compile unit for the given descriptor.
///
CompileUnit *DwarfDebug::findCompileUnit(DICompileUnit Unit) {
  DenseMap<Value *, CompileUnit *>::const_iterator I =
    CompileUnitMap.find(Unit.getNode());
  if (I == CompileUnitMap.end())
    return constructCompileUnit(Unit.getNode());
  return I->second;
}

/// getUpdatedDbgScope - Find or create DbgScope assicated with the instruction.
/// Initialize scope and update scope hierarchy.
DbgScope *DwarfDebug::getUpdatedDbgScope(MDNode *N, const MachineInstr *MI,
  MDNode *InlinedAt) {
  assert (N && "Invalid Scope encoding!");
  assert (MI && "Missing machine instruction!");
  bool GetConcreteScope = (MI && InlinedAt);

  DbgScope *NScope = NULL;

  if (InlinedAt)
    NScope = DbgScopeMap.lookup(InlinedAt);
  else
    NScope = DbgScopeMap.lookup(N);
  assert (NScope && "Unable to find working scope!");

  if (NScope->getFirstInsn())
    return NScope;

  DbgScope *Parent = NULL;
  if (GetConcreteScope) {
    DILocation IL(InlinedAt);
    Parent = getUpdatedDbgScope(IL.getScope().getNode(), MI,
                         IL.getOrigLocation().getNode());
    assert (Parent && "Unable to find Parent scope!");
    NScope->setParent(Parent);
    Parent->addScope(NScope);
  } else if (DIDescriptor(N).isLexicalBlock()) {
    DILexicalBlock DB(N);
    if (!DB.getContext().isNull()) {
      Parent = getUpdatedDbgScope(DB.getContext().getNode(), MI, InlinedAt);
      NScope->setParent(Parent);
      Parent->addScope(NScope);
    }
  }

  NScope->setFirstInsn(MI);

  if (!Parent && !InlinedAt) {
    StringRef SPName = DISubprogram(N).getLinkageName();
    if (SPName == MF->getFunction()->getName())
      CurrentFnDbgScope = NScope;
  }

  if (GetConcreteScope) {
    ConcreteScopes[InlinedAt] = NScope;
    getOrCreateAbstractScope(N);
  }

  return NScope;
}

DbgScope *DwarfDebug::getOrCreateAbstractScope(MDNode *N) {
  assert (N && "Invalid Scope encoding!");

  DbgScope *AScope = AbstractScopes.lookup(N);
  if (AScope)
    return AScope;

  DbgScope *Parent = NULL;

  DIDescriptor Scope(N);
  if (Scope.isLexicalBlock()) {
    DILexicalBlock DB(N);
    DIDescriptor ParentDesc = DB.getContext();
    if (!ParentDesc.isNull())
      Parent = getOrCreateAbstractScope(ParentDesc.getNode());
  }

  AScope = new DbgScope(Parent, DIDescriptor(N), NULL);

  if (Parent)
    Parent->addScope(AScope);
  AScope->setAbstractScope();
  AbstractScopes[N] = AScope;
  if (DIDescriptor(N).isSubprogram())
    AbstractScopesList.push_back(AScope);
  return AScope;
}

/// updateSubprogramScopeDIE - Find DIE for the given subprogram and
/// attach appropriate DW_AT_low_pc and DW_AT_high_pc attributes.
/// If there are global variables in this scope then create and insert
/// DIEs for these variables.
DIE *DwarfDebug::updateSubprogramScopeDIE(MDNode *SPNode) {

 DIE *SPDie = ModuleCU->getDIE(SPNode);
 assert (SPDie && "Unable to find subprogram DIE!");
 DISubprogram SP(SPNode);
 if (SP.isDefinition() && !SP.getContext().isCompileUnit()) {
   addUInt(SPDie, dwarf::DW_AT_declaration, dwarf::DW_FORM_flag, 1);
  // Add arguments. 
   DICompositeType SPTy = SP.getType();
   DIArray Args = SPTy.getTypeArray();
   unsigned SPTag = SPTy.getTag();
   if (SPTag == dwarf::DW_TAG_subroutine_type)
     for (unsigned i = 1, N =  Args.getNumElements(); i < N; ++i) {
       DIE *Arg = new DIE(dwarf::DW_TAG_formal_parameter);
       addType(Arg, DIType(Args.getElement(i).getNode()));
       addUInt(Arg, dwarf::DW_AT_artificial, dwarf::DW_FORM_flag, 1); // ??
       SPDie->addChild(Arg);
     }
   DIE *SPDeclDie = SPDie;
   SPDie = new DIE(dwarf::DW_TAG_subprogram);
   addDIEEntry(SPDie, dwarf::DW_AT_specification, dwarf::DW_FORM_ref4, 
               SPDeclDie);
   ModuleCU->addDie(SPDie);
 }
   
 addLabel(SPDie, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
          DWLabel("func_begin", SubprogramCount));
 addLabel(SPDie, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
          DWLabel("func_end", SubprogramCount));
 MachineLocation Location(RI->getFrameRegister(*MF));
 addAddress(SPDie, dwarf::DW_AT_frame_base, Location);

 if (!DISubprogram(SPNode).isLocalToUnit())
   addUInt(SPDie, dwarf::DW_AT_external, dwarf::DW_FORM_flag, 1);

 return SPDie;
}

/// constructLexicalScope - Construct new DW_TAG_lexical_block
/// for this scope and attach DW_AT_low_pc/DW_AT_high_pc labels.
DIE *DwarfDebug::constructLexicalScopeDIE(DbgScope *Scope) {
  unsigned StartID = MMI->MappedLabel(Scope->getStartLabelID());
  unsigned EndID = MMI->MappedLabel(Scope->getEndLabelID());

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

  DIE *ScopeDIE = new DIE(dwarf::DW_TAG_lexical_block);
  if (Scope->isAbstractScope())
    return ScopeDIE;

  addLabel(ScopeDIE, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
           StartID ?
             DWLabel("label", StartID)
           : DWLabel("func_begin", SubprogramCount));
  addLabel(ScopeDIE, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
           EndID ?
             DWLabel("label", EndID)
           : DWLabel("func_end", SubprogramCount));



  return ScopeDIE;
}

/// constructInlinedScopeDIE - This scope represents inlined body of
/// a function. Construct DIE to represent this concrete inlined copy
/// of the function.
DIE *DwarfDebug::constructInlinedScopeDIE(DbgScope *Scope) {
  unsigned StartID = MMI->MappedLabel(Scope->getStartLabelID());
  unsigned EndID = MMI->MappedLabel(Scope->getEndLabelID());
  assert (StartID && "Invalid starting label for an inlined scope!");
  assert (EndID && "Invalid end label for an inlined scope!");
  // Ignore empty scopes.
  if (StartID == EndID && StartID != 0)
    return NULL;

  DIScope DS(Scope->getScopeNode());
  if (DS.isNull())
    return NULL;
  DIE *ScopeDIE = new DIE(dwarf::DW_TAG_inlined_subroutine);

  DISubprogram InlinedSP = getDISubprogram(DS.getNode());
  DIE *OriginDIE = ModuleCU->getDIE(InlinedSP.getNode());
  assert (OriginDIE && "Unable to find Origin DIE!");
  addDIEEntry(ScopeDIE, dwarf::DW_AT_abstract_origin,
              dwarf::DW_FORM_ref4, OriginDIE);

  addLabel(ScopeDIE, dwarf::DW_AT_low_pc, dwarf::DW_FORM_addr,
           DWLabel("label", StartID));
  addLabel(ScopeDIE, dwarf::DW_AT_high_pc, dwarf::DW_FORM_addr,
           DWLabel("label", EndID));

  InlinedSubprogramDIEs.insert(OriginDIE);

  // Track the start label for this inlined function.
  ValueMap<MDNode *, SmallVector<InlineInfoLabels, 4> >::iterator
    I = InlineInfo.find(InlinedSP.getNode());

  if (I == InlineInfo.end()) {
    InlineInfo[InlinedSP.getNode()].push_back(std::make_pair(StartID,
                                                             ScopeDIE));
    InlinedSPNodes.push_back(InlinedSP.getNode());
  } else
    I->second.push_back(std::make_pair(StartID, ScopeDIE));

  StringPool.insert(InlinedSP.getName());
  StringPool.insert(getRealLinkageName(InlinedSP.getLinkageName()));

  DILocation DL(Scope->getInlinedAt());
  addUInt(ScopeDIE, dwarf::DW_AT_call_file, 0, ModuleCU->getID());
  addUInt(ScopeDIE, dwarf::DW_AT_call_line, 0, DL.getLineNumber());

  return ScopeDIE;
}


/// constructVariableDIE - Construct a DIE for the given DbgVariable.
DIE *DwarfDebug::constructVariableDIE(DbgVariable *DV, DbgScope *Scope) {
  // Get the descriptor.
  const DIVariable &VD = DV->getVariable();
  StringRef Name = VD.getName();
  if (Name.empty())
    return NULL;

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

  // Define variable debug information entry.
  DIE *VariableDie = new DIE(Tag);


  DIE *AbsDIE = NULL;
  if (DbgVariable *AV = DV->getAbstractVariable())
    AbsDIE = AV->getDIE();

  if (AbsDIE) {
    DIScope DS(Scope->getScopeNode());
    DISubprogram InlinedSP = getDISubprogram(DS.getNode());
    DIE *OriginSPDIE = ModuleCU->getDIE(InlinedSP.getNode());
    (void) OriginSPDIE;
    assert (OriginSPDIE && "Unable to find Origin DIE for the SP!");
    DIE *AbsDIE = DV->getAbstractVariable()->getDIE();
    assert (AbsDIE && "Unable to find Origin DIE for the Variable!");
    addDIEEntry(VariableDie, dwarf::DW_AT_abstract_origin,
                dwarf::DW_FORM_ref4, AbsDIE);
  }
  else {
    addString(VariableDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);
    addSourceLine(VariableDie, &VD);

    // Add variable type.
    // FIXME: isBlockByrefVariable should be reformulated in terms of complex
    // addresses instead.
    if (VD.isBlockByrefVariable())
      addType(VariableDie, getBlockByrefType(VD.getType(), Name));
    else
      addType(VariableDie, VD.getType());
  }

  // Add variable address.
  if (!Scope->isAbstractScope()) {
    MachineLocation Location;
    unsigned FrameReg;
    int Offset = RI->getFrameIndexReference(*MF, DV->getFrameIndex(), FrameReg);
    Location.set(FrameReg, Offset);

    if (VD.hasComplexAddress())
      addComplexAddress(DV, VariableDie, dwarf::DW_AT_location, Location);
    else if (VD.isBlockByrefVariable())
      addBlockByrefAddress(DV, VariableDie, dwarf::DW_AT_location, Location);
    else
      addAddress(VariableDie, dwarf::DW_AT_location, Location);
  }
  DV->setDIE(VariableDie);
  return VariableDie;

}

void DwarfDebug::addPubTypes(DISubprogram SP) {
  DICompositeType SPTy = SP.getType();
  unsigned SPTag = SPTy.getTag();
  if (SPTag != dwarf::DW_TAG_subroutine_type) 
    return;

  DIArray Args = SPTy.getTypeArray();
  if (Args.isNull()) 
    return;

  for (unsigned i = 0, e = Args.getNumElements(); i != e; ++i) {
    DIType ATy(Args.getElement(i).getNode());
    if (ATy.isNull())
      continue;
    DICompositeType CATy = getDICompositeType(ATy);
    if (!CATy.isNull() && !CATy.getName().empty()) {
      if (DIEEntry *Entry = ModuleCU->getDIEEntry(CATy.getNode()))
        ModuleCU->addGlobalType(CATy.getName(), Entry->getEntry());
    }
  }
}

/// constructScopeDIE - Construct a DIE for this scope.
DIE *DwarfDebug::constructScopeDIE(DbgScope *Scope) {
 if (!Scope)
  return NULL;
 DIScope DS(Scope->getScopeNode());
 if (DS.isNull())
   return NULL;

 DIE *ScopeDIE = NULL;
 if (Scope->getInlinedAt())
   ScopeDIE = constructInlinedScopeDIE(Scope);
 else if (DS.isSubprogram()) {
   if (Scope->isAbstractScope())
     ScopeDIE = ModuleCU->getDIE(DS.getNode());
   else
     ScopeDIE = updateSubprogramScopeDIE(DS.getNode());
 }
 else {
   ScopeDIE = constructLexicalScopeDIE(Scope);
   if (!ScopeDIE) return NULL;
 }

  // Add variables to scope.
  SmallVector<DbgVariable *, 8> &Variables = Scope->getVariables();
  for (unsigned i = 0, N = Variables.size(); i < N; ++i) {
    DIE *VariableDIE = constructVariableDIE(Variables[i], Scope);
    if (VariableDIE)
      ScopeDIE->addChild(VariableDIE);
  }

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

  if (DS.isSubprogram()) 
    addPubTypes(DISubprogram(DS.getNode()));
 
 return ScopeDIE;
}

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

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

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

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

  return SrcId;
}

/// getOrCreateNameSpace - Create a DIE for DINameSpace.
DIE *DwarfDebug::getOrCreateNameSpace(DINameSpace NS) {
  DIE *NDie = ModuleCU->getDIE(NS.getNode());
  if (NDie)
    return NDie;
  NDie = new DIE(dwarf::DW_TAG_namespace);
  ModuleCU->insertDIE(NS.getNode(), NDie);
  if (!NS.getName().empty())
    addString(NDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, NS.getName());
  addSourceLine(NDie, &NS);
  addToContextOwner(NDie, NS.getContext());
  return NDie;
}

CompileUnit *DwarfDebug::constructCompileUnit(MDNode *N) {
  DICompileUnit DIUnit(N);
  StringRef FN = DIUnit.getFilename();
  StringRef Dir = DIUnit.getDirectory();
  unsigned ID = GetOrCreateSourceID(Dir, FN);

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

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

  StringRef Flags = DIUnit.getFlags();
  if (!Flags.empty())
    addString(Die, dwarf::DW_AT_APPLE_flags, dwarf::DW_FORM_string, Flags);

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

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

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

void DwarfDebug::constructGlobalVariableDIE(MDNode *N) {
  DIGlobalVariable DI_GV(N);

  // If debug information is malformed then ignore it.
  if (DI_GV.Verify() == false)
    return;

  // Check for pre-existence.
  if (ModuleCU->getDIE(DI_GV.getNode()))
    return;

  DIE *VariableDie = createGlobalVariableDIE(DI_GV);
  if (!VariableDie)
    return;

  // Add to map.
  ModuleCU->insertDIE(N, VariableDie);

  // Add to context owner.
  if (DI_GV.isDefinition() 
      && !DI_GV.getContext().isCompileUnit()) {
    // Create specification DIE.
    DIE *VariableSpecDIE = new DIE(dwarf::DW_TAG_variable);
    addDIEEntry(VariableSpecDIE, dwarf::DW_AT_specification,
                dwarf::DW_FORM_ref4, VariableDie);
    DIEBlock *Block = new DIEBlock();
    addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_addr);
    addObjectLabel(Block, 0, dwarf::DW_FORM_udata,
                   Asm->Mang->getMangledName(DI_GV.getGlobal()));
    addBlock(VariableSpecDIE, dwarf::DW_AT_location, 0, Block);
    ModuleCU->addDie(VariableSpecDIE);
  } else {
    DIEBlock *Block = new DIEBlock();
    addUInt(Block, 0, dwarf::DW_FORM_data1, dwarf::DW_OP_addr);
    addObjectLabel(Block, 0, dwarf::DW_FORM_udata,
                   Asm->Mang->getMangledName(DI_GV.getGlobal()));
    addBlock(VariableDie, dwarf::DW_AT_location, 0, Block);
  }
  addToContextOwner(VariableDie, DI_GV.getContext());
  
  // Expose as global. FIXME - need to check external flag.
  ModuleCU->addGlobal(DI_GV.getName(), VariableDie);

  DIType GTy = DI_GV.getType();
  if (GTy.isCompositeType() && !GTy.getName().empty()) {
    DIEEntry *Entry = ModuleCU->getDIEEntry(GTy.getNode());
    assert (Entry && "Missing global type!");
    ModuleCU->addGlobalType(GTy.getName(), Entry->getEntry());
  }
  return;
}

void DwarfDebug::constructSubprogramDIE(MDNode *N) {
  DISubprogram SP(N);

  // Check for pre-existence.
  if (ModuleCU->getDIE(N))
    return;

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

  DIE *SubprogramDie = createSubprogramDIE(SP);

  // Add to map.
  ModuleCU->insertDIE(N, SubprogramDie);

  // Add to context owner.
  addToContextOwner(SubprogramDie, SP.getContext());

  // Expose as global.
  ModuleCU->addGlobal(SP.getName(), SubprogramDie);

  return;
}

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

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  if (!MAI->doesSupportDebugInformation())
    return;

  DebugInfoFinder DbgFinder;
  DbgFinder.processModule(*M);

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

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

    return;
  }

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

  // Create DIEs for each subprogram.
  for (DebugInfoFinder::iterator I = DbgFinder.subprogram_begin(),
         E = DbgFinder.subprogram_end(); I != E; ++I)
    constructSubprogramDIE(*I);

  // Create DIEs for each global variable.
  for (DebugInfoFinder::iterator I = DbgFinder.global_variable_begin(),
         E = DbgFinder.global_variable_end(); I != E; ++I)
    constructGlobalVariableDIE(*I);

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

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

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

  // Emit initial sections
  emitInitial();

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

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

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  // Attach DW_AT_inline attribute with inlined subprogram DIEs.
  for (SmallPtrSet<DIE *, 4>::iterator AI = InlinedSubprogramDIEs.begin(),
         AE = InlinedSubprogramDIEs.end(); AI != AE; ++AI) {
    DIE *ISP = *AI;
    addUInt(ISP, dwarf::DW_AT_inline, 0, dwarf::DW_INL_inlined);
  }

  // Insert top level DIEs.
  for (SmallVector<DIE *, 4>::iterator TI = TopLevelDIEsVector.begin(),
         TE = TopLevelDIEsVector.end(); TI != TE; ++TI)
    ModuleCU->getCUDie()->addChild(*TI);

  for (DenseMap<DIE *, WeakVH>::iterator CI = ContainingTypeMap.begin(),
         CE = ContainingTypeMap.end(); CI != CE; ++CI) {
    DIE *SPDie = CI->first;
    MDNode *N = dyn_cast_or_null<MDNode>(CI->second);
    if (!N) continue;
    DIE *NDie = ModuleCU->getDIE(N);
    if (!NDie) continue;
    addDIEEntry(SPDie, dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4, NDie);
    addDIEEntry(NDie, dwarf::DW_AT_containing_type, dwarf::DW_FORM_ref4, NDie);
  }

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

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

  // Emit common frame information.
  emitCommonDebugFrame();

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

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

  // 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 pubtypes section.
  emitDebugPubTypes();

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

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

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

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

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

  // Emit inline info.
  emitDebugInlineInfo();

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

/// findAbstractVariable - Find abstract variable, if any, associated with Var.
DbgVariable *DwarfDebug::findAbstractVariable(DIVariable &Var,
                                              unsigned FrameIdx,
                                              DILocation &ScopeLoc) {

  DbgVariable *AbsDbgVariable = AbstractVariables.lookup(Var.getNode());
  if (AbsDbgVariable)
    return AbsDbgVariable;

  DbgScope *Scope = AbstractScopes.lookup(ScopeLoc.getScope().getNode());
  if (!Scope)
    return NULL;

  AbsDbgVariable = new DbgVariable(Var, FrameIdx);
  Scope->addVariable(AbsDbgVariable);
  AbstractVariables[Var.getNode()] = AbsDbgVariable;
  return AbsDbgVariable;
}

/// collectVariableInfo - Populate DbgScope entries with variables' info.
void DwarfDebug::collectVariableInfo() {
  if (!MMI) return;

  MachineModuleInfo::VariableDbgInfoMapTy &VMap = MMI->getVariableDbgInfo();
  for (MachineModuleInfo::VariableDbgInfoMapTy::iterator VI = VMap.begin(),
         VE = VMap.end(); VI != VE; ++VI) {
    MetadataBase *MB = VI->first;
    MDNode *Var = dyn_cast_or_null<MDNode>(MB);
    if (!Var) continue;
    DIVariable DV (Var);
    std::pair< unsigned, MDNode *> VP = VI->second;
    DILocation ScopeLoc(VP.second);

    DbgScope *Scope =
      ConcreteScopes.lookup(ScopeLoc.getOrigLocation().getNode());
    if (!Scope)
      Scope = DbgScopeMap.lookup(ScopeLoc.getScope().getNode());
    // If variable scope is not found then skip this variable.
    if (!Scope)
      continue;

    DbgVariable *RegVar = new DbgVariable(DV, VP.first);
    Scope->addVariable(RegVar);
    if (DbgVariable *AbsDbgVariable = findAbstractVariable(DV, VP.first,
                                                           ScopeLoc))
      RegVar->setAbstractVariable(AbsDbgVariable);
  }
}

/// beginScope - Process beginning of a scope starting at Label.
void DwarfDebug::beginScope(const MachineInstr *MI, unsigned Label) {
  InsnToDbgScopeMapTy::iterator I = DbgScopeBeginMap.find(MI);
  if (I == DbgScopeBeginMap.end())
    return;
  ScopeVector &SD = I->second;
  for (ScopeVector::iterator SDI = SD.begin(), SDE = SD.end();
       SDI != SDE; ++SDI)
    (*SDI)->setStartLabelID(Label);
}

/// endScope - Process end of a scope.
void DwarfDebug::endScope(const MachineInstr *MI) {
  InsnToDbgScopeMapTy::iterator I = DbgScopeEndMap.find(MI);
  if (I == DbgScopeEndMap.end())
    return;

  unsigned Label = MMI->NextLabelID();
  Asm->printLabel(Label);
  O << '\n';

  SmallVector<DbgScope *, 2> &SD = I->second;
  for (SmallVector<DbgScope *, 2>::iterator SDI = SD.begin(), SDE = SD.end();
       SDI != SDE; ++SDI)
    (*SDI)->setEndLabelID(Label);
  return;
}

/// createDbgScope - Create DbgScope for the scope.
void DwarfDebug::createDbgScope(MDNode *Scope, MDNode *InlinedAt) {

  if (!InlinedAt) {
    DbgScope *WScope = DbgScopeMap.lookup(Scope);
    if (WScope)
      return;
    WScope = new DbgScope(NULL, DIDescriptor(Scope), NULL);
    DbgScopeMap.insert(std::make_pair(Scope, WScope));
    if (DIDescriptor(Scope).isLexicalBlock())
      createDbgScope(DILexicalBlock(Scope).getContext().getNode(), NULL);
    return;
  }

  DbgScope *WScope = DbgScopeMap.lookup(InlinedAt);
  if (WScope)
    return;

  WScope = new DbgScope(NULL, DIDescriptor(Scope), InlinedAt);
  DbgScopeMap.insert(std::make_pair(InlinedAt, WScope));
  DILocation DL(InlinedAt);
  createDbgScope(DL.getScope().getNode(), DL.getOrigLocation().getNode());
}

/// extractScopeInformation - Scan machine instructions in this function
/// and collect DbgScopes. Return true, if atleast one scope was found.
bool DwarfDebug::extractScopeInformation(MachineFunction *MF) {
  // If scope information was extracted using .dbg intrinsics then there is not
  // any need to extract these information by scanning each instruction.
  if (!DbgScopeMap.empty())
    return false;

  DenseMap<const MachineInstr *, unsigned> MIIndexMap;
  unsigned MIIndex = 0;
  // Scan each instruction and create scopes. First build working set of scopes.
  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
       I != E; ++I) {
    for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
         II != IE; ++II) {
      const MachineInstr *MInsn = II;
      MIIndexMap[MInsn] = MIIndex++;
      DebugLoc DL = MInsn->getDebugLoc();
      if (DL.isUnknown()) continue;
      DebugLocTuple DLT = MF->getDebugLocTuple(DL);