DwarfDebug.cpp

    // Skip special LLVM prefix that is used to inform the asm printer to not
    // emit usual symbol prefix before the symbol name. This happens for
    // Objective-C symbol names and symbol whose name is replaced using GCC's
    // __asm__ attribute.
    if (LinkageName[0] == 1)
      LinkageName = &LinkageName[1];
    AddString(GVDie, dwarf::DW_AT_MIPS_linkage_name, dwarf::DW_FORM_string,
              LinkageName);
  }
  AddType(DW_Unit, GVDie, GV.getType());
  if (!GV.isLocalToUnit())
    AddUInt(GVDie, dwarf::DW_AT_external, dwarf::DW_FORM_flag, 1);
  AddSourceLine(GVDie, &GV);

  // Add address.
  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(GV.getGlobal()));
  AddBlock(GVDie, dwarf::DW_AT_location, 0, Block);

  return GVDie;
}

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

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

  return MemberDie;
}

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

  const char * Name = SP.getName();
  AddString(SPDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);

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

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

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

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

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

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

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

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

/// CreateDbgScopeVariable - Create a new scope variable.
///
DIE *DwarfDebug::CreateDbgScopeVariable(DbgVariable *DV, CompileUnit *Unit) {
  // Get the descriptor.
  const DIVariable &VD = DV->getVariable();
  const char *Name = VD.getName();
  if (!Name)
    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);
  AddString(VariableDie, dwarf::DW_AT_name, dwarf::DW_FORM_string, Name);

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

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

  // Add variable address.
  // Variables for abstract instances of inlined functions don't get a
  // location.
  MachineLocation Location;
  Location.set(RI->getFrameRegister(*MF),
               RI->getFrameIndexOffset(*MF, DV->getFrameIndex()));
  
  
  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);

  return VariableDie;
}

/// 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;
}

static DISubprogram getDISubprogram(MDNode *N) {

  DIDescriptor D(N);
  if (D.isNull())
    return DISubprogram();

  if (D.isCompileUnit()) 
    return DISubprogram();

  if (D.isSubprogram())
    return DISubprogram(N);

  if (D.isLexicalBlock())
    return getDISubprogram(DILexicalBlock(N).getContext().getNode());

  llvm_unreachable("Unexpected Descriptor!");
}

DIE *DwarfDebug::UpdateSubprogramScopeDIE(MDNode *SPNode) {

 DIE *SPDie = ModuleCU->getDIE(SPNode);
 assert (SPDie && "Unable to find subprogram DIE!");
 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);

 // If there are global variables at this scope then add their dies.
 for (SmallVector<WeakVH, 4>::iterator SGI = ScopedGVs.begin(), 
        SGE = ScopedGVs.end(); SGI != SGE; ++SGI) {
   MDNode *N = dyn_cast_or_null<MDNode>(*SGI);
   if (!N) continue;
   DIGlobalVariable GV(N);
   if (GV.getContext().getNode() == SPNode) {
     DIE *ScopedGVDie = CreateGlobalVariableDIE(ModuleCU, GV);
     if (ScopedGVDie)
       SPDie->AddChild(ScopedGVDie);
   }
 }
 return SPDie;
}

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;
}

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(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;
}

DIE *DwarfDebug::ConstructVariableDIE(DbgVariable *DV, 
                                      DbgScope *Scope, CompileUnit *Unit) {
  // Get the descriptor.
  const DIVariable &VD = DV->getVariable();
  const char *Name = VD.getName();
  if (!Name)
    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(Unit, VariableDie, GetBlockByrefType(VD.getType(), Name));
    else
      AddType(Unit, VariableDie, VD.getType());
  }

  // Add variable address.
  if (!Scope->isAbstractScope()) {
    MachineLocation Location;
    Location.set(RI->getFrameRegister(*MF),
                 RI->getFrameIndexOffset(*MF, DV->getFrameIndex()));
    
    
    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;

}
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, ModuleCU);
    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);
  }
  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(const char *DirName,
                                         const char *FileName) {
  unsigned DId;
  StringMap<unsigned>::iterator DI = DirectoryIdMap.find(DirName);
  if (DI != DirectoryIdMap.end()) {
    DId = DI->getValue();
  } else {
    DId = DirectoryNames.size() + 1;
    DirectoryIdMap[DirName] = DId;
    DirectoryNames.push_back(DirName);
  }

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

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

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

  return SrcId;
}

void DwarfDebug::ConstructCompileUnit(MDNode *N) {
  DICompileUnit DIUnit(N);
  const char *FN = DIUnit.getFilename();
  const char *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)
    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);

  if (const char *Flags = DIUnit.getFlags())
    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);
}

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(ModuleCU, DI_GV);

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

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

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

void DwarfDebug::ConstructSubprogram(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(ModuleCU, SP);

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

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

  // 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 of the externally visible global variables.
  for (DebugInfoFinder::iterator I = DbgFinder.global_variable_begin(),
         E = DbgFinder.global_variable_end(); I != E; ++I) {
    DIGlobalVariable GV(*I);
    if (GV.getContext().getNode() != GV.getCompileUnit().getNode())
      ScopedGVs.push_back(*I);
    else
      ConstructGlobalVariableDIE(*I);
  }

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

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

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

  // Print out .file directives to specify files for .loc directives. These are
  // printed out early so that they precede any .loc directives.
  if (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);
  }

  // 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.
  SizeAndOffsets();

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

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

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

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

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

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

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

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

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

  // Emit inline info.
  EmitDebugInlineInfo();

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

/// 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 = DbgScopeBeginMap[MI];
  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);

  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;

  // 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;
      DebugLoc DL = MInsn->getDebugLoc();
      if (DL.isUnknown()) continue;
      DebugLocTuple DLT = MF->getDebugLocTuple(DL);
      if (!DLT.Scope) continue;
      // There is no need to create another DIE for compile unit. For all
      // other scopes, create one DbgScope now. This will be translated 
      // into a scope DIE at the end.
      if (DIDescriptor(DLT.Scope).isCompileUnit()) continue;
      createDbgScope(DLT.Scope, DLT.InlinedAtLoc);
    }
  }


  // Build scope hierarchy using 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;
      DebugLoc DL = MInsn->getDebugLoc();
      if (DL.isUnknown())  continue;
      DebugLocTuple DLT = MF->getDebugLocTuple(DL);
      if (!DLT.Scope)  continue;
      // There is no need to create another DIE for compile unit. For all
      // other scopes, create one DbgScope now. This will be translated 
      // into a scope DIE at the end.
      if (DIDescriptor(DLT.Scope).isCompileUnit()) continue;
      DbgScope *Scope = getUpdatedDbgScope(DLT.Scope, MInsn, DLT.InlinedAtLoc);
      Scope->setLastInsn(MInsn);
    }
  }

  // If a scope's last instruction is not set then use its child scope's
  // last instruction as this scope's last instrunction.
  for (ValueMap<MDNode *, DbgScope *>::iterator DI = DbgScopeMap.begin(),
	 DE = DbgScopeMap.end(); DI != DE; ++DI) {
    if (DI->second->isAbstractScope())
      continue;
    assert (DI->second->getFirstInsn() && "Invalid first instruction!");
    DI->second->FixInstructionMarkers();
    assert (DI->second->getLastInsn() && "Invalid last instruction!");
  }

  // Each scope has first instruction and last instruction to mark beginning
  // and end of a scope respectively. Create an inverse map that list scopes
  // starts (and ends) with an instruction. One instruction may start (or end)
  // multiple scopes.
  for (ValueMap<MDNode *, DbgScope *>::iterator DI = DbgScopeMap.begin(),
	 DE = DbgScopeMap.end(); DI != DE; ++DI) {
    DbgScope *S = DI->second;
    if (S->isAbstractScope())
      continue;
    const MachineInstr *MI = S->getFirstInsn();
    assert (MI && "DbgScope does not have first instruction!");

    InsnToDbgScopeMapTy::iterator IDI = DbgScopeBeginMap.find(MI);
    if (IDI != DbgScopeBeginMap.end())
      IDI->second.push_back(S);
    else
      DbgScopeBeginMap[MI].push_back(S);

    MI = S->getLastInsn();
    assert (MI && "DbgScope does not have last instruction!");
    IDI = DbgScopeEndMap.find(MI);
    if (IDI != DbgScopeEndMap.end())
      IDI->second.push_back(S);
    else
      DbgScopeEndMap[MI].push_back(S);
  }

  return !DbgScopeMap.empty();
}

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

  if (!ShouldEmitDwarfDebug()) return;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  if (!ExtractScopeInformation(MF))
    return;
  CollectVariableInfo();

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

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

  // Emit label for the implicitly defined dbg.stoppoint at the start of the
  // function.
  DebugLoc FDL = MF->getDefaultDebugLoc();
  if (!FDL.isUnknown()) {
    DebugLocTuple DLT = MF->getDebugLocTuple(FDL);