DwarfDebug.cpp

  // Collect variable information from DBG_VALUE machine instructions;
  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;
      if (MInsn->getOpcode() != TargetOpcode::DBG_VALUE)
        continue;
      // FIXME : Lift this restriction.
      if (MInsn->getNumOperands() != 3)
        continue;
      DIVariable DV((MDNode*)(MInsn->getOperand(MInsn->getNumOperands() - 1).getMetadata()));
      if (DV.getTag() == dwarf::DW_TAG_arg_variable)  {
        // FIXME Handle inlined subroutine arguments.
        DbgVariable *ArgVar = new DbgVariable(DV, MInsn, NULL);
        CurrentFnDbgScope->addVariable(ArgVar);
        continue;
      }

      DebugLoc DL = MInsn->getDebugLoc();
      if (DL.isUnknown()) continue;
      DILocation ScopeLoc = MF->getDILocation(DL);
      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 *AbsDbgVariable = findAbstractVariable(DV, MInsn,
                                                         ScopeLoc);
      DbgVariable *RegVar = new DbgVariable(DV, MInsn, AbsDbgVariable);
      Scope->addVariable(RegVar);
    }
  }
}

/// beginScope - Process beginning of a scope starting at Label.
void DwarfDebug::beginScope(const MachineInstr *MI, MCSymbol *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)->setStartLabel(Label);
}

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

  MCSymbol *Label = MMI->getContext().CreateTempSymbol();
  Asm->OutStreamer.EmitLabel(Label);

  SmallVector<DbgScope*, 2> &SD = I->second;
  for (SmallVector<DbgScope *, 2>::iterator SDI = SD.begin(), SDE = SD.end();
       SDI != SDE; ++SDI)
    (*SDI)->setEndLabel(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() {
  // 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;
      // FIXME : Remove DBG_VALUE check.
      if (MInsn->getOpcode() == TargetOpcode::DBG_VALUE) continue;
      MIIndexMap[MInsn] = MIIndex++;
      DebugLoc DL = MInsn->getDebugLoc();
      if (DL.isUnknown()) continue;
      DILocation DLT = MF->getDILocation(DL);
      DIScope DLTScope = DLT.getScope();
      // 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 (DLTScope.isCompileUnit()) continue;
      createDbgScope(DLTScope.getNode(), DLT.getOrigLocation().getNode());
    }
  }


  // 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;
      // FIXME : Remove DBG_VALUE check.
      if (MInsn->getOpcode() == TargetOpcode::DBG_VALUE) continue;
      DebugLoc DL = MInsn->getDebugLoc();
      if (DL.isUnknown())  continue;
      DILocation DLT = MF->getDILocation(DL);
      DIScope DLTScope = DLT.getScope();
      // 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 (DLTScope.isCompileUnit()) continue;
      DbgScope *Scope = getUpdatedDbgScope(DLTScope.getNode(), MInsn, 
                                           DLT.getOrigLocation().getNode());
      Scope->setLastInsn(MInsn);
    }
  }

  if (!CurrentFnDbgScope)
    return false;

  CurrentFnDbgScope->fixInstructionMarkers(MIIndexMap);

  // 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. Ignore scopes that are not reachable.
  SmallVector<DbgScope *, 4> WorkList;
  WorkList.push_back(CurrentFnDbgScope);
  while (!WorkList.empty()) {
    DbgScope *S = WorkList.back(); WorkList.pop_back();

    const SmallVector<DbgScope *, 4> &Children = S->getScopes();
    if (!Children.empty()) 
      for (SmallVector<DbgScope *, 4>::const_iterator SI = Children.begin(),
             SE = Children.end(); SI != SE; ++SI)
        WorkList.push_back(*SI);

    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(const MachineFunction *MF) {
  this->MF = MF;

  if (!ShouldEmitDwarfDebug()) return;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  if (!extractScopeInformation())
    return;

  collectVariableInfo();

  // Assumes in correct section after the entry point.
  Asm->OutStreamer.EmitLabel(getDWLabel("func_begin", ++SubprogramCount));

  // Emit label for the implicitly defined dbg.stoppoint at the start of the
  // function.
  DebugLoc FDL = MF->getDefaultDebugLoc();
  if (!FDL.isUnknown()) {
    DILocation DLT = MF->getDILocation(FDL);
    DISubprogram SP = getDISubprogram(DLT.getScope().getNode());
    unsigned Line, Col;
    if (SP.Verify()) {
      Line = SP.getLineNumber();
      Col = 0;
    } else {
      Line = DLT.getLineNumber();
      Col = DLT.getColumnNumber();
    }
    
    recordSourceLine(Line, Col, DLT.getScope().getNode());
  }
  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

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

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  if (DbgScopeMap.empty())
    return;

  if (CurrentFnDbgScope) {
    // Define end label for subprogram.
    Asm->OutStreamer.EmitLabel(getDWLabel("func_end", SubprogramCount));
    
    // Get function line info.
    if (!Lines.empty()) {
      // Get section line info.
      unsigned ID = SectionMap.insert(Asm->getCurrentSection());
      if (SectionSourceLines.size() < ID) SectionSourceLines.resize(ID);
      std::vector<SrcLineInfo> &SectionLineInfos = SectionSourceLines[ID-1];
      // Append the function info to section info.
      SectionLineInfos.insert(SectionLineInfos.end(),
                              Lines.begin(), Lines.end());
    }
    
    // Construct abstract scopes.
    for (SmallVector<DbgScope *, 4>::iterator AI = AbstractScopesList.begin(),
           AE = AbstractScopesList.end(); AI != AE; ++AI)
      constructScopeDIE(*AI);
    
    constructScopeDIE(CurrentFnDbgScope);
    
    DebugFrames.push_back(FunctionDebugFrameInfo(SubprogramCount,
                                                 MMI->getFrameMoves()));
  }

  // Clear debug info
  CurrentFnDbgScope = NULL;
  DeleteContainerSeconds(DbgScopeMap);
  DbgScopeBeginMap.clear();
  DbgScopeEndMap.clear();
  ConcreteScopes.clear();
  DeleteContainerSeconds(AbstractScopes);
  AbstractScopesList.clear();
  AbstractVariables.clear();
  Lines.clear();
  
  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();
}

/// recordSourceLine - Register a source line with debug info. Returns the
/// unique label that was emitted and which provides correspondence to
/// the source line list.
MCSymbol *DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, MDNode *S) {
  if (!MMI)
    return 0;

  if (TimePassesIsEnabled)
    DebugTimer->startTimer();

  StringRef Dir;
  StringRef Fn;

  DIDescriptor Scope(S);
  if (Scope.isCompileUnit()) {
    DICompileUnit CU(S);
    Dir = CU.getDirectory();
    Fn = CU.getFilename();
  } else if (Scope.isSubprogram()) {
    DISubprogram SP(S);
    Dir = SP.getDirectory();
    Fn = SP.getFilename();
  } else if (Scope.isLexicalBlock()) {
    DILexicalBlock DB(S);
    Dir = DB.getDirectory();
    Fn = DB.getFilename();
  } else
    assert(0 && "Unexpected scope info");

  unsigned Src = GetOrCreateSourceID(Dir, Fn);
  MCSymbol *Label = MMI->getContext().CreateTempSymbol();
  Lines.push_back(SrcLineInfo(Line, Col, Src, Label));

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  Asm->OutStreamer.EmitLabel(Label);
  return Label;
}

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

  unsigned SrcId = GetOrCreateSourceID(DirName.c_str(), FileName.c_str());

  if (TimePassesIsEnabled)
    DebugTimer->stopTimer();

  return SrcId;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  computeSizeAndOffset(ModuleCU->getCUDie(), Offset, true);
  CompileUnitOffsets[ModuleCU] = 0;
}

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

  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();

  // Dwarf sections base addresses.
  if (MAI->doesDwarfRequireFrameSection()) {
    Asm->OutStreamer.SwitchSection(TLOF.getDwarfFrameSection());
    Asm->OutStreamer.EmitLabel(getTempLabel("section_debug_frame"));
  }

  Asm->OutStreamer.SwitchSection(TLOF.getDwarfInfoSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_info"));
  Asm->OutStreamer.SwitchSection(TLOF.getDwarfAbbrevSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_abbrev"));
  Asm->OutStreamer.SwitchSection(TLOF.getDwarfARangesSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_aranges"));

  if (const MCSection *LineInfoDirective = TLOF.getDwarfMacroInfoSection()) {
    Asm->OutStreamer.SwitchSection(LineInfoDirective);
    Asm->OutStreamer.EmitLabel(getTempLabel("section_macinfo"));
  }

  Asm->OutStreamer.SwitchSection(TLOF.getDwarfLineSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_line"));
  Asm->OutStreamer.SwitchSection(TLOF.getDwarfLocSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_loc"));
  Asm->OutStreamer.SwitchSection(TLOF.getDwarfPubNamesSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_pubnames"));
  Asm->OutStreamer.SwitchSection(TLOF.getDwarfPubTypesSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_pubtypes"));
  Asm->OutStreamer.SwitchSection(TLOF.getDwarfStrSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_str"));
  Asm->OutStreamer.SwitchSection(TLOF.getDwarfRangesSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("section_ranges"));

  Asm->OutStreamer.SwitchSection(TLOF.getTextSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("text_begin"));
  Asm->OutStreamer.SwitchSection(TLOF.getDataSection());
  Asm->OutStreamer.EmitLabel(getTempLabel("data_begin"));
}

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

  // Emit the code (index) for the abbreviation.
  if (Asm->VerboseAsm)
    Asm->OutStreamer.AddComment("Abbrev [" + Twine(AbbrevNumber) + "] 0x" +
                                Twine::utohexstr(Die->getOffset()) + ":0x" +
                                Twine::utohexstr(Die->getSize()) + " " +
                                dwarf::TagString(Abbrev->getTag()));
  EmitULEB128(AbbrevNumber);

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

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

    if (Asm->VerboseAsm)
      Asm->OutStreamer.AddComment(dwarf::AttributeString(Attr));
    
    switch (Attr) {
    case dwarf::DW_AT_sibling:
      Asm->EmitInt32(Die->getSiblingOffset());
      break;
    case dwarf::DW_AT_abstract_origin: {
      DIEEntry *E = cast<DIEEntry>(Values[i]);
      DIE *Origin = E->getEntry();
      unsigned Addr = Origin->getOffset();
      Asm->EmitInt32(Addr);
      break;
    }
    default:
      // Emit an attribute using the defined form.
      Values[i]->EmitValue(this, Form);
      break;
    }
  }

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

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

    if (Asm->VerboseAsm)
      Asm->OutStreamer.AddComment("End Of Children Mark");
    Asm->EmitInt8(0);
  }
}

/// emitDebugInfo - Emit the debug info section.
///
void DwarfDebug::emitDebugInfo() {
  // Start debug info section.
  Asm->OutStreamer.SwitchSection(
                            Asm->getObjFileLowering().getDwarfInfoSection());
  DIE *Die = ModuleCU->getCUDie();

  // Emit the compile units header.
  Asm->OutStreamer.EmitLabel(getDWLabel("info_begin", ModuleCU->getID()));

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

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

  emitDIE(Die);
  // FIXME - extra padding for gdb bug.
  Asm->OutStreamer.AddComment("4 extra padding bytes for GDB");
  Asm->EmitInt8(0);
  Asm->EmitInt8(0);
  Asm->EmitInt8(0);
  Asm->EmitInt8(0);
  Asm->OutStreamer.EmitLabel(getDWLabel("info_end", ModuleCU->getID()));
}

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

    Asm->OutStreamer.EmitLabel(getTempLabel("abbrev_begin"));

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

      // Emit the abbrevations code (base 1 index.)
      EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");

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

    // Mark end of abbreviations.
    EmitULEB128(0, "EOM(3)");

    Asm->OutStreamer.EmitLabel(getTempLabel("abbrev_end"));
  }
}

/// emitEndOfLineMatrix - Emit the last address of the section and the end of
/// the line matrix.
///
void DwarfDebug::emitEndOfLineMatrix(unsigned SectionEnd) {
  // Define last address of section.
  Asm->OutStreamer.AddComment("Extended Op");
  Asm->EmitInt8(0);
  
  Asm->OutStreamer.AddComment("Op size");
  Asm->EmitInt8(TD->getPointerSize() + 1);
  Asm->OutStreamer.AddComment("DW_LNE_set_address");
  Asm->EmitInt8(dwarf::DW_LNE_set_address);

  Asm->OutStreamer.AddComment("Section end label");

  Asm->OutStreamer.EmitSymbolValue(getDWLabel("section_end", SectionEnd),
                                   TD->getPointerSize(), 0/*AddrSpace*/);

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

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

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

  // Start the dwarf line section.
  Asm->OutStreamer.SwitchSection(
                            Asm->getObjFileLowering().getDwarfLineSection());

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

  Asm->OutStreamer.AddComment("DWARF version number");
  Asm->EmitInt16(dwarf::DWARF_VERSION); 

  Asm->OutStreamer.AddComment("Prolog Length");
  EmitDifference(getTempLabel("line_prolog_end"),
                 getTempLabel("line_prolog_begin"), true);
  Asm->OutStreamer.EmitLabel(getTempLabel("line_prolog_begin"));

  Asm->OutStreamer.AddComment("Minimum Instruction Length");
  Asm->EmitInt8(1);
  Asm->OutStreamer.AddComment("Default is_stmt_start flag");
  Asm->EmitInt8(1);
  Asm->OutStreamer.AddComment("Line Base Value (Special Opcodes)");
  Asm->EmitInt8(MinLineDelta);
  Asm->OutStreamer.AddComment("Line Range Value (Special Opcodes)");
  Asm->EmitInt8(MaxLineDelta);
  Asm->OutStreamer.AddComment("Special Opcode Base");
  Asm->EmitInt8(-MinLineDelta);

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

  // Emit directories.
  for (unsigned DI = 1, DE = getNumSourceDirectories()+1; DI != DE; ++DI) {
    const std::string &Dir = getSourceDirectoryName(DI);
    if (Asm->VerboseAsm) Asm->OutStreamer.AddComment("Directory");
    Asm->OutStreamer.EmitBytes(StringRef(Dir.c_str(), Dir.size()+1), 0);
  }

  Asm->OutStreamer.AddComment("End of directories");
  Asm->EmitInt8(0);

  // Emit files.
  for (unsigned SI = 1, SE = getNumSourceIds()+1; SI != SE; ++SI) {
    // Remember source id starts at 1.
    std::pair<unsigned, unsigned> Id = getSourceDirectoryAndFileIds(SI);
    const std::string &FN = getSourceFileName(Id.second);
    if (Asm->VerboseAsm) Asm->OutStreamer.AddComment("Source");
    Asm->OutStreamer.EmitBytes(StringRef(FN.c_str(), FN.size()+1), 0);
    
    EmitULEB128(Id.first, "Directory #");
    EmitULEB128(0, "Mod date");
    EmitULEB128(0, "File size");
  }

  Asm->OutStreamer.AddComment("End of files");
  Asm->EmitInt8(0);

  Asm->OutStreamer.EmitLabel(getTempLabel("line_prolog_end"));

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

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

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

    // Construct rows of the address, source, line, column matrix.
    for (unsigned i = 0, N = LineInfos.size(); i < N; ++i) {
      const SrcLineInfo &LineInfo = LineInfos[i];
      MCSymbol *Label = LineInfo.getLabel();
      if (!Label->isDefined()) continue; // Not emitted, in dead code.

      if (LineInfo.getLine() == 0) continue;

      if (Asm->isVerbose()) {
        std::pair<unsigned, unsigned> SrcID =
          getSourceDirectoryAndFileIds(LineInfo.getSourceID());
        Asm->OutStreamer.AddComment(Twine(getSourceDirectoryName(SrcID.first)) +
                                    "/" +
                                    Twine(getSourceFileName(SrcID.second)) +
                                    ":" + Twine(LineInfo.getLine()));
      }

      // Define the line address.
      Asm->OutStreamer.AddComment("Extended Op");
      Asm->EmitInt8(0);
      Asm->OutStreamer.AddComment("Op size");
      Asm->EmitInt8(TD->getPointerSize() + 1);

      Asm->OutStreamer.AddComment("DW_LNE_set_address");
      Asm->EmitInt8(dwarf::DW_LNE_set_address); 

      Asm->OutStreamer.AddComment("Location label");
      Asm->OutStreamer.EmitSymbolValue(Label, TD->getPointerSize(),
                                       0/*AddrSpace*/);
      
      // If change of source, then switch to the new source.
      if (Source != LineInfo.getSourceID()) {
        Source = LineInfo.getSourceID();
        Asm->OutStreamer.AddComment("DW_LNS_set_file");
        Asm->EmitInt8(dwarf::DW_LNS_set_file); 
        EmitULEB128(Source, "New Source");
      }

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

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

        // If delta is small enough and in range...
        if (Delta >= 0 && Delta < (MaxLineDelta - 1)) {
          // ... then use fast opcode.
          Asm->OutStreamer.AddComment("Line Delta");
          Asm->EmitInt8(Delta - MinLineDelta);
        } else {
          // ... otherwise use long hand.
          Asm->OutStreamer.AddComment("DW_LNS_advance_line");
          Asm->EmitInt8(dwarf::DW_LNS_advance_line);
          EmitSLEB128(Offset, "Line Offset");
          Asm->OutStreamer.AddComment("DW_LNS_copy");
          Asm->EmitInt8(dwarf::DW_LNS_copy);
        }
      } else {
        // Copy the previous row (different address or source)
        Asm->OutStreamer.AddComment("DW_LNS_copy");
        Asm->EmitInt8(dwarf::DW_LNS_copy);
      }
    }

    emitEndOfLineMatrix(j + 1);
  }

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

  Asm->OutStreamer.EmitLabel(getTempLabel("line_end"));
}

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

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

  // Start the dwarf frame section.
  Asm->OutStreamer.SwitchSection(
                              Asm->getObjFileLowering().getDwarfFrameSection());

  Asm->OutStreamer.EmitLabel(getTempLabel("debug_frame_common"));
  Asm->OutStreamer.AddComment("Length of Common Information Entry");
  EmitDifference(getTempLabel("debug_frame_common_end"),
                 getTempLabel("debug_frame_common_begin"), true);

  Asm->OutStreamer.EmitLabel(getTempLabel("debug_frame_common_begin"));
  Asm->OutStreamer.AddComment("CIE Identifier Tag");
  Asm->EmitInt32((int)dwarf::DW_CIE_ID);
  Asm->OutStreamer.AddComment("CIE Version");
  Asm->EmitInt8(dwarf::DW_CIE_VERSION);
  Asm->OutStreamer.AddComment("CIE Augmentation");
  Asm->OutStreamer.EmitIntValue(0, 1, /*addrspace*/0); // nul terminator.
  EmitULEB128(1, "CIE Code Alignment Factor");
  EmitSLEB128(stackGrowth, "CIE Data Alignment Factor");
  Asm->OutStreamer.AddComment("CIE RA Column");
  Asm->EmitInt8(RI->getDwarfRegNum(RI->getRARegister(), false));

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

  EmitFrameMoves(0, Moves, false);

  Asm->EmitAlignment(2, 0, 0, false);
  Asm->OutStreamer.EmitLabel(getTempLabel("debug_frame_common_end"));
}

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

  // Start the dwarf frame section.
  Asm->OutStreamer.SwitchSection(
                              Asm->getObjFileLowering().getDwarfFrameSection());

  Asm->OutStreamer.AddComment("Length of Frame Information Entry");
  MCSymbol *DebugFrameBegin =
    getDWLabel("debug_frame_begin", DebugFrameInfo.Number);
  MCSymbol *DebugFrameEnd =
    getDWLabel("debug_frame_end", DebugFrameInfo.Number);
  EmitDifference(DebugFrameEnd, DebugFrameBegin, true);

  Asm->OutStreamer.EmitLabel(DebugFrameBegin);

  Asm->OutStreamer.AddComment("FDE CIE offset");
  EmitSectionOffset(getTempLabel("debug_frame_common"), 
                    getTempLabel("section_debug_frame"), true);

  Asm->OutStreamer.AddComment("FDE initial location");
  MCSymbol *FuncBeginSym = getDWLabel("func_begin", DebugFrameInfo.Number);
  Asm->OutStreamer.EmitSymbolValue(FuncBeginSym,
                                   TD->getPointerSize(), 0/*AddrSpace*/);
  
  
  Asm->OutStreamer.AddComment("FDE address range");
  EmitDifference(getDWLabel("func_end", DebugFrameInfo.Number), FuncBeginSym);

  EmitFrameMoves(FuncBeginSym, DebugFrameInfo.Moves, false);

  Asm->EmitAlignment(2, 0, 0, false);
  Asm->OutStreamer.EmitLabel(DebugFrameEnd);
}

/// emitDebugPubNames - Emit visible names into a debug pubnames section.
///
void DwarfDebug::emitDebugPubNames() {
  // Start the dwarf pubnames section.
  Asm->OutStreamer.SwitchSection(
                          Asm->getObjFileLowering().getDwarfPubNamesSection());

  Asm->OutStreamer.AddComment("Length of Public Names Info");
  EmitDifference(getDWLabel("pubnames_end", ModuleCU->getID()),
                 getDWLabel("pubnames_begin", ModuleCU->getID()), true);

  Asm->OutStreamer.EmitLabel(getDWLabel("pubnames_begin", ModuleCU->getID()));

  Asm->OutStreamer.AddComment("DWARF Version");
  Asm->EmitInt16(dwarf::DWARF_VERSION); 

  Asm->OutStreamer.AddComment("Offset of Compilation Unit Info");
  EmitSectionOffset(getDWLabel("info_begin", ModuleCU->getID()), 
                    getTempLabel("section_info"), true);

  Asm->OutStreamer.AddComment("Compilation Unit Length");
  EmitDifference(getDWLabel("info_end", ModuleCU->getID()),
                 getDWLabel("info_begin", ModuleCU->getID()),
                 true);

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

    Asm->OutStreamer.AddComment("DIE offset");
    Asm->EmitInt32(Entity->getOffset());
    
    if (Asm->VerboseAsm)
      Asm->OutStreamer.AddComment("External Name");
    Asm->OutStreamer.EmitBytes(StringRef(Name, strlen(Name)+1), 0);
  }

  Asm->OutStreamer.AddComment("End Mark");
  Asm->EmitInt32(0);
  Asm->OutStreamer.EmitLabel(getDWLabel("pubnames_end", ModuleCU->getID()));
}

void DwarfDebug::emitDebugPubTypes() {
  // Start the dwarf pubnames section.
  Asm->OutStreamer.SwitchSection(
                          Asm->getObjFileLowering().getDwarfPubTypesSection());
  Asm->OutStreamer.AddComment("Length of Public Types Info");
  EmitDifference(getDWLabel("pubtypes_end", ModuleCU->getID()),
                 getDWLabel("pubtypes_begin", ModuleCU->getID()), true);

  Asm->OutStreamer.EmitLabel(getDWLabel("pubtypes_begin", ModuleCU->getID()));

  if (Asm->VerboseAsm) Asm->OutStreamer.AddComment("DWARF Version");
  Asm->EmitInt16(dwarf::DWARF_VERSION);

  Asm->OutStreamer.AddComment("Offset of Compilation ModuleCU Info");
  EmitSectionOffset(getDWLabel("info_begin", ModuleCU->getID()),
                    getTempLabel("section_info"), true);

  Asm->OutStreamer.AddComment("Compilation ModuleCU Length");
  EmitDifference(getDWLabel("info_end", ModuleCU->getID()),
                 getDWLabel("info_begin", ModuleCU->getID()),
                 true);

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

    if (Asm->VerboseAsm) Asm->OutStreamer.AddComment("DIE offset");
    Asm->EmitInt32(Entity->getOffset());
    
    if (Asm->VerboseAsm) Asm->OutStreamer.AddComment("External Name");
    Asm->OutStreamer.EmitBytes(StringRef(Name, GI->getKeyLength()+1), 0);
  }

  Asm->OutStreamer.AddComment("End Mark");
  Asm->EmitInt32(0); 
  Asm->OutStreamer.EmitLabel(getDWLabel("pubtypes_end", ModuleCU->getID()));
}

/// emitDebugStr - Emit visible names into a debug str section.
///
void DwarfDebug::emitDebugStr() {
  // Check to see if it is worth the effort.
  if (StringPool.empty()) return;
  
  // Start the dwarf str section.
  Asm->OutStreamer.SwitchSection(
                                Asm->getObjFileLowering().getDwarfStrSection());

  // Get all of the string pool entries and put them in an array by their ID so
  // we can sort them.
  SmallVector<std::pair<unsigned, 
      StringMapEntry<std::pair<MCSymbol*, unsigned> >*>, 64> Entries;
  
  for (StringMap<std::pair<MCSymbol*, unsigned> >::iterator
       I = StringPool.begin(), E = StringPool.end(); I != E; ++I)
    Entries.push_back(std::make_pair(I->second.second, &*I));
  
  array_pod_sort(Entries.begin(), Entries.end());
  
  for (unsigned i = 0, e = Entries.size(); i != e; ++i) {
    // Emit a label for reference from debug information entries.
    Asm->OutStreamer.EmitLabel(Entries[i].second->getValue().first);
    
    // Emit the string itself.
    Asm->OutStreamer.EmitBytes(Entries[i].second->getKey(), 0/*addrspace*/);
  }
}

/// emitDebugLoc - Emit visible names into a debug loc section.
///
void DwarfDebug::emitDebugLoc() {
  // Start the dwarf loc section.
  Asm->OutStreamer.SwitchSection(
                              Asm->getObjFileLowering().getDwarfLocSection());
}

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

/// emitDebugRanges - Emit visible names into a debug ranges section.
///
void DwarfDebug::emitDebugRanges() {
  // Start the dwarf ranges section.
  Asm->OutStreamer.SwitchSection(
                            Asm->getObjFileLowering().getDwarfRangesSection());
}

/// emitDebugMacInfo - Emit visible names into a debug macinfo section.
///
void DwarfDebug::emitDebugMacInfo() {
  if (const MCSection *LineInfo =
      Asm->getObjFileLowering().getDwarfMacroInfoSection()) {