DwarfDebug.cpp

  }
}

/// isDbgValueInDefinedReg - Return true if debug value, encoded by
/// DBG_VALUE instruction, is in a defined reg.
static bool isDbgValueInDefinedReg(const MachineInstr *MI) {
  assert(MI->isDebugValue() && "Invalid DBG_VALUE machine instruction!");
  return MI->getNumOperands() == 3 &&
         MI->getOperand(0).isReg() && MI->getOperand(0).getReg() &&
         MI->getOperand(1).isImm() && MI->getOperand(1).getImm() == 0;
}

/// getDebugLocEntry - Get .debug_loc entry for the instruction range starting
/// at MI.
static DotDebugLocEntry getDebugLocEntry(AsmPrinter *Asm, 
                                         const MCSymbol *FLabel, 
                                         const MCSymbol *SLabel,
                                         const MachineInstr *MI) {
  const MDNode *Var =  MI->getOperand(MI->getNumOperands() - 1).getMetadata();

  if (MI->getNumOperands() != 3) {
    MachineLocation MLoc = Asm->getDebugValueLocation(MI);
    return DotDebugLocEntry(FLabel, SLabel, MLoc, Var);
  }
  if (MI->getOperand(0).isReg() && MI->getOperand(1).isImm()) {
    MachineLocation MLoc;
    MLoc.set(MI->getOperand(0).getReg(), MI->getOperand(1).getImm());
    return DotDebugLocEntry(FLabel, SLabel, MLoc, Var);
  }
  if (MI->getOperand(0).isImm())
    return DotDebugLocEntry(FLabel, SLabel, MI->getOperand(0).getImm());
  if (MI->getOperand(0).isFPImm())
    return DotDebugLocEntry(FLabel, SLabel, MI->getOperand(0).getFPImm());
  if (MI->getOperand(0).isCImm())
    return DotDebugLocEntry(FLabel, SLabel, MI->getOperand(0).getCImm());

  llvm_unreachable("Unexpected 3 operand DBG_VALUE instruction!");
}

/// collectVariableInfo - Find variables for each lexical scope.
void
DwarfDebug::collectVariableInfo(const MachineFunction *MF,
                                SmallPtrSet<const MDNode *, 16> &Processed) {

  /// collection info from MMI table.
  collectVariableInfoFromMMITable(MF, Processed);

  for (SmallVectorImpl<const MDNode*>::const_iterator
         UVI = UserVariables.begin(), UVE = UserVariables.end(); UVI != UVE;
         ++UVI) {
    const MDNode *Var = *UVI;
    if (Processed.count(Var))
      continue;

    // History contains relevant DBG_VALUE instructions for Var and instructions
    // clobbering it.
    SmallVectorImpl<const MachineInstr*> &History = DbgValues[Var];
    if (History.empty())
      continue;
    const MachineInstr *MInsn = History.front();

    DIVariable DV(Var);
    LexicalScope *Scope = NULL;
    if (DV.getTag() == dwarf::DW_TAG_arg_variable &&
        DISubprogram(DV.getContext()).describes(MF->getFunction()))
      Scope = LScopes.getCurrentFunctionScope();
    else {
      if (DV.getVersion() <= LLVMDebugVersion9)
        Scope = LScopes.findLexicalScope(MInsn->getDebugLoc());
      else {
        if (MDNode *IA = DV.getInlinedAt())
          Scope = LScopes.findInlinedScope(DebugLoc::getFromDILocation(IA));
        else
          Scope = LScopes.findLexicalScope(cast<MDNode>(DV->getOperand(1)));
      }
    }
    // If variable scope is not found then skip this variable.
    if (!Scope)
      continue;

    Processed.insert(DV);
    assert(MInsn->isDebugValue() && "History must begin with debug value");
    DbgVariable *AbsVar = findAbstractVariable(DV, MInsn->getDebugLoc());
    DbgVariable *RegVar = new DbgVariable(DV, AbsVar);
    if (!addCurrentFnArgument(MF, RegVar, Scope))
      addScopeVariable(Scope, RegVar);
    if (AbsVar)
      AbsVar->setMInsn(MInsn);

    // Simplify ranges that are fully coalesced.
    if (History.size() <= 1 || (History.size() == 2 &&
                                MInsn->isIdenticalTo(History.back()))) {
      RegVar->setMInsn(MInsn);
      continue;
    }

    // handle multiple DBG_VALUE instructions describing one variable.
    RegVar->setDotDebugLocOffset(DotDebugLocEntries.size());

    for (SmallVectorImpl<const MachineInstr*>::const_iterator
           HI = History.begin(), HE = History.end(); HI != HE; ++HI) {
      const MachineInstr *Begin = *HI;
      assert(Begin->isDebugValue() && "Invalid History entry");

      // Check if DBG_VALUE is truncating a range.
      if (Begin->getNumOperands() > 1 && Begin->getOperand(0).isReg()
          && !Begin->getOperand(0).getReg())
        continue;

      // Compute the range for a register location.
      const MCSymbol *FLabel = getLabelBeforeInsn(Begin);
      const MCSymbol *SLabel = 0;

      if (HI + 1 == HE)
        // If Begin is the last instruction in History then its value is valid
        // until the end of the function.
        SLabel = FunctionEndSym;
      else {
        const MachineInstr *End = HI[1];
        DEBUG(dbgs() << "DotDebugLoc Pair:\n" 
              << "\t" << *Begin << "\t" << *End << "\n");
        if (End->isDebugValue())
          SLabel = getLabelBeforeInsn(End);
        else {
          // End is a normal instruction clobbering the range.
          SLabel = getLabelAfterInsn(End);
          assert(SLabel && "Forgot label after clobber instruction");
          ++HI;
        }
      }

      // The value is valid until the next DBG_VALUE or clobber.
      DotDebugLocEntries.push_back(getDebugLocEntry(Asm, FLabel, SLabel,
                                                    Begin));
    }
    DotDebugLocEntries.push_back(DotDebugLocEntry());
  }

  // Collect info for variables that were optimized out.
  LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
  DIArray Variables = DISubprogram(FnScope->getScopeNode()).getVariables();
  for (unsigned i = 0, e = Variables.getNumElements(); i != e; ++i) {
    DIVariable DV(Variables.getElement(i));
    if (!DV || !DV.Verify() || !Processed.insert(DV))
      continue;
    if (LexicalScope *Scope = LScopes.findLexicalScope(DV.getContext()))
      addScopeVariable(Scope, new DbgVariable(DV, NULL));
  }
}

/// getLabelBeforeInsn - Return Label preceding the instruction.
const MCSymbol *DwarfDebug::getLabelBeforeInsn(const MachineInstr *MI) {
  MCSymbol *Label = LabelsBeforeInsn.lookup(MI);
  assert(Label && "Didn't insert label before instruction");
  return Label;
}

/// getLabelAfterInsn - Return Label immediately following the instruction.
const MCSymbol *DwarfDebug::getLabelAfterInsn(const MachineInstr *MI) {
  return LabelsAfterInsn.lookup(MI);
}

/// beginInstruction - Process beginning of an instruction.
void DwarfDebug::beginInstruction(const MachineInstr *MI) {
  // Check if source location changes, but ignore DBG_VALUE locations.
  if (!MI->isDebugValue()) {
    DebugLoc DL = MI->getDebugLoc();
    if (DL != PrevInstLoc && (!DL.isUnknown() || UnknownLocations)) {
      unsigned Flags = 0;
      PrevInstLoc = DL;
      if (DL == PrologEndLoc) {
        Flags |= DWARF2_FLAG_PROLOGUE_END;
        PrologEndLoc = DebugLoc();
      }
      if (PrologEndLoc.isUnknown())
        Flags |= DWARF2_FLAG_IS_STMT;

      if (!DL.isUnknown()) {
        const MDNode *Scope = DL.getScope(Asm->MF->getFunction()->getContext());
        recordSourceLine(DL.getLine(), DL.getCol(), Scope, Flags);
      } else
        recordSourceLine(0, 0, 0, 0);
    }
  }

  // Insert labels where requested.
  DenseMap<const MachineInstr*, MCSymbol*>::iterator I =
    LabelsBeforeInsn.find(MI);

  // No label needed.
  if (I == LabelsBeforeInsn.end())
    return;

  // Label already assigned.
  if (I->second)
    return;

  if (!PrevLabel) {
    PrevLabel = MMI->getContext().CreateTempSymbol();
    Asm->OutStreamer.EmitLabel(PrevLabel);
  }
  I->second = PrevLabel;
}

/// endInstruction - Process end of an instruction.
void DwarfDebug::endInstruction(const MachineInstr *MI) {
  // Don't create a new label after DBG_VALUE instructions.
  // They don't generate code.
  if (!MI->isDebugValue())
    PrevLabel = 0;

  DenseMap<const MachineInstr*, MCSymbol*>::iterator I =
    LabelsAfterInsn.find(MI);

  // No label needed.
  if (I == LabelsAfterInsn.end())
    return;

  // Label already assigned.
  if (I->second)
    return;

  // We need a label after this instruction.
  if (!PrevLabel) {
    PrevLabel = MMI->getContext().CreateTempSymbol();
    Asm->OutStreamer.EmitLabel(PrevLabel);
  }
  I->second = PrevLabel;
}

/// identifyScopeMarkers() -
/// Each LexicalScope 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.
void DwarfDebug::identifyScopeMarkers() {
  SmallVector<LexicalScope *, 4> WorkList;
  WorkList.push_back(LScopes.getCurrentFunctionScope());
  while (!WorkList.empty()) {
    LexicalScope *S = WorkList.pop_back_val();

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

    if (S->isAbstractScope())
      continue;

    const SmallVector<InsnRange, 4> &Ranges = S->getRanges();
    if (Ranges.empty())
      continue;
    for (SmallVector<InsnRange, 4>::const_iterator RI = Ranges.begin(),
           RE = Ranges.end(); RI != RE; ++RI) {
      assert(RI->first && "InsnRange does not have first instruction!");
      assert(RI->second && "InsnRange does not have second instruction!");
      requestLabelBeforeInsn(RI->first);
      requestLabelAfterInsn(RI->second);
    }
  }
}

/// getScopeNode - Get MDNode for DebugLoc's scope.
static MDNode *getScopeNode(DebugLoc DL, const LLVMContext &Ctx) {
  if (MDNode *InlinedAt = DL.getInlinedAt(Ctx))
    return getScopeNode(DebugLoc::getFromDILocation(InlinedAt), Ctx);
  return DL.getScope(Ctx);
}

/// getFnDebugLoc - Walk up the scope chain of given debug loc and find
/// line number info for the function.
static DebugLoc getFnDebugLoc(DebugLoc DL, const LLVMContext &Ctx) {
  const MDNode *Scope = getScopeNode(DL, Ctx);
  DISubprogram SP = getDISubprogram(Scope);
  if (SP.Verify()) {
    // Check for number of operands since the compatibility is
    // cheap here.
    if (SP->getNumOperands() > 19)
      return DebugLoc::get(SP.getScopeLineNumber(), 0, SP);
    else
      return DebugLoc::get(SP.getLineNumber(), 0, SP);
  }

  return DebugLoc();
}

/// beginFunction - Gather pre-function debug information.  Assumes being
/// emitted immediately after the function entry point.
void DwarfDebug::beginFunction(const MachineFunction *MF) {
  if (!MMI->hasDebugInfo()) return;
  LScopes.initialize(*MF);
  if (LScopes.empty()) return;
  identifyScopeMarkers();

  FunctionBeginSym = Asm->GetTempSymbol("func_begin",
                                        Asm->getFunctionNumber());
  // Assumes in correct section after the entry point.
  Asm->OutStreamer.EmitLabel(FunctionBeginSym);

  assert(UserVariables.empty() && DbgValues.empty() && "Maps weren't cleaned");

  const TargetRegisterInfo *TRI = Asm->TM.getRegisterInfo();
  /// LiveUserVar - Map physreg numbers to the MDNode they contain.
  std::vector<const MDNode*> LiveUserVar(TRI->getNumRegs());

  for (MachineFunction::const_iterator I = MF->begin(), E = MF->end();
       I != E; ++I) {
    bool AtBlockEntry = true;
    for (MachineBasicBlock::const_iterator II = I->begin(), IE = I->end();
         II != IE; ++II) {
      const MachineInstr *MI = II;

      if (MI->isDebugValue()) {
        assert(MI->getNumOperands() > 1 && "Invalid machine instruction!");

        // Keep track of user variables.
        const MDNode *Var =
          MI->getOperand(MI->getNumOperands() - 1).getMetadata();

        // Variable is in a register, we need to check for clobbers.
        if (isDbgValueInDefinedReg(MI))
          LiveUserVar[MI->getOperand(0).getReg()] = Var;

        // Check the history of this variable.
        SmallVectorImpl<const MachineInstr*> &History = DbgValues[Var];
        if (History.empty()) {
          UserVariables.push_back(Var);
          // The first mention of a function argument gets the FunctionBeginSym
          // label, so arguments are visible when breaking at function entry.
          DIVariable DV(Var);
          if (DV.Verify() && DV.getTag() == dwarf::DW_TAG_arg_variable &&
              DISubprogram(getDISubprogram(DV.getContext()))
                .describes(MF->getFunction()))
            LabelsBeforeInsn[MI] = FunctionBeginSym;
        } else {
          // We have seen this variable before. Try to coalesce DBG_VALUEs.
          const MachineInstr *Prev = History.back();
          if (Prev->isDebugValue()) {
            // Coalesce identical entries at the end of History.
            if (History.size() >= 2 &&
                Prev->isIdenticalTo(History[History.size() - 2])) {
              DEBUG(dbgs() << "Coalescing identical DBG_VALUE entries:\n"
                    << "\t" << *Prev 
                    << "\t" << *History[History.size() - 2] << "\n");
              History.pop_back();
            }

            // Terminate old register assignments that don't reach MI;
            MachineFunction::const_iterator PrevMBB = Prev->getParent();
            if (PrevMBB != I && (!AtBlockEntry || llvm::next(PrevMBB) != I) &&
                isDbgValueInDefinedReg(Prev)) {
              // Previous register assignment needs to terminate at the end of
              // its basic block.
              MachineBasicBlock::const_iterator LastMI =
                PrevMBB->getLastNonDebugInstr();
              if (LastMI == PrevMBB->end()) {
                // Drop DBG_VALUE for empty range.
                DEBUG(dbgs() << "Dropping DBG_VALUE for empty range:\n"
                      << "\t" << *Prev << "\n");
                History.pop_back();
              }
              else {
                // Terminate after LastMI.
                History.push_back(LastMI);
              }
            }
          }
        }
        History.push_back(MI);
      } else {
        // Not a DBG_VALUE instruction.
        if (!MI->isLabel())
          AtBlockEntry = false;

        // First known non-DBG_VALUE and non-frame setup location marks
        // the beginning of the function body.
        if (!MI->getFlag(MachineInstr::FrameSetup) &&
            (PrologEndLoc.isUnknown() && !MI->getDebugLoc().isUnknown()))
          PrologEndLoc = MI->getDebugLoc();

        // Check if the instruction clobbers any registers with debug vars.
        for (MachineInstr::const_mop_iterator MOI = MI->operands_begin(),
               MOE = MI->operands_end(); MOI != MOE; ++MOI) {
          if (!MOI->isReg() || !MOI->isDef() || !MOI->getReg())
            continue;
          for (MCRegAliasIterator AI(MOI->getReg(), TRI, true);
               AI.isValid(); ++AI) {
            unsigned Reg = *AI;
            const MDNode *Var = LiveUserVar[Reg];
            if (!Var)
              continue;
            // Reg is now clobbered.
            LiveUserVar[Reg] = 0;

            // Was MD last defined by a DBG_VALUE referring to Reg?
            DbgValueHistoryMap::iterator HistI = DbgValues.find(Var);
            if (HistI == DbgValues.end())
              continue;
            SmallVectorImpl<const MachineInstr*> &History = HistI->second;
            if (History.empty())
              continue;
            const MachineInstr *Prev = History.back();
            // Sanity-check: Register assignments are terminated at the end of
            // their block.
            if (!Prev->isDebugValue() || Prev->getParent() != MI->getParent())
              continue;
            // Is the variable still in Reg?
            if (!isDbgValueInDefinedReg(Prev) ||
                Prev->getOperand(0).getReg() != Reg)
              continue;
            // Var is clobbered. Make sure the next instruction gets a label.
            History.push_back(MI);
          }
        }
      }
    }
  }

  for (DbgValueHistoryMap::iterator I = DbgValues.begin(), E = DbgValues.end();
       I != E; ++I) {
    SmallVectorImpl<const MachineInstr*> &History = I->second;
    if (History.empty())
      continue;

    // Make sure the final register assignments are terminated.
    const MachineInstr *Prev = History.back();
    if (Prev->isDebugValue() && isDbgValueInDefinedReg(Prev)) {
      const MachineBasicBlock *PrevMBB = Prev->getParent();
      MachineBasicBlock::const_iterator LastMI = 
        PrevMBB->getLastNonDebugInstr();
      if (LastMI == PrevMBB->end())
        // Drop DBG_VALUE for empty range.
        History.pop_back();
      else {
        // Terminate after LastMI.
        History.push_back(LastMI);
      }
    }
    // Request labels for the full history.
    for (unsigned i = 0, e = History.size(); i != e; ++i) {
      const MachineInstr *MI = History[i];
      if (MI->isDebugValue())
        requestLabelBeforeInsn(MI);
      else
        requestLabelAfterInsn(MI);
    }
  }

  PrevInstLoc = DebugLoc();
  PrevLabel = FunctionBeginSym;

  // Record beginning of function.
  if (!PrologEndLoc.isUnknown()) {
    DebugLoc FnStartDL = getFnDebugLoc(PrologEndLoc,
                                       MF->getFunction()->getContext());
    recordSourceLine(FnStartDL.getLine(), FnStartDL.getCol(),
                     FnStartDL.getScope(MF->getFunction()->getContext()),
                     0);
  }
}

void DwarfDebug::addScopeVariable(LexicalScope *LS, DbgVariable *Var) {
//  SmallVector<DbgVariable *, 8> &Vars = ScopeVariables.lookup(LS);
  ScopeVariables[LS].push_back(Var);
//  Vars.push_back(Var);
}

/// endFunction - Gather and emit post-function debug information.
///
void DwarfDebug::endFunction(const MachineFunction *MF) {
  if (!MMI->hasDebugInfo() || LScopes.empty()) return;

  // Define end label for subprogram.
  FunctionEndSym = Asm->GetTempSymbol("func_end",
                                      Asm->getFunctionNumber());
  // Assumes in correct section after the entry point.
  Asm->OutStreamer.EmitLabel(FunctionEndSym);
  
  SmallPtrSet<const MDNode *, 16> ProcessedVars;
  collectVariableInfo(MF, ProcessedVars);
  
  LexicalScope *FnScope = LScopes.getCurrentFunctionScope();
  CompileUnit *TheCU = SPMap.lookup(FnScope->getScopeNode());
  assert(TheCU && "Unable to find compile unit!");

  // Construct abstract scopes.
  ArrayRef<LexicalScope *> AList = LScopes.getAbstractScopesList();
  for (unsigned i = 0, e = AList.size(); i != e; ++i) {
    LexicalScope *AScope = AList[i];
    DISubprogram SP(AScope->getScopeNode());
    if (SP.Verify()) {
      // Collect info for variables that were optimized out.
      DIArray Variables = SP.getVariables();
      for (unsigned i = 0, e = Variables.getNumElements(); i != e; ++i) {
        DIVariable DV(Variables.getElement(i));
        if (!DV || !DV.Verify() || !ProcessedVars.insert(DV))
          continue;
        // Check that DbgVariable for DV wasn't created earlier, when
        // findAbstractVariable() was called for inlined instance of DV.
        LLVMContext &Ctx = DV->getContext();
        DIVariable CleanDV = cleanseInlinedVariable(DV, Ctx);
        if (AbstractVariables.lookup(CleanDV))
          continue;
        if (LexicalScope *Scope = LScopes.findAbstractScope(DV.getContext()))
          addScopeVariable(Scope, new DbgVariable(DV, NULL));
      }
    }
    if (ProcessedSPNodes.count(AScope->getScopeNode()) == 0)
      constructScopeDIE(TheCU, AScope);
  }
  
  DIE *CurFnDIE = constructScopeDIE(TheCU, FnScope);
  
  if (!MF->getTarget().Options.DisableFramePointerElim(*MF))
    TheCU->addFlag(CurFnDIE, dwarf::DW_AT_APPLE_omit_frame_ptr);

  DebugFrames.push_back(FunctionDebugFrameInfo(Asm->getFunctionNumber(),
                                               MMI->getFrameMoves()));

  // Clear debug info
  for (DenseMap<LexicalScope *, SmallVector<DbgVariable *, 8> >::iterator
         I = ScopeVariables.begin(), E = ScopeVariables.end(); I != E; ++I)
    DeleteContainerPointers(I->second);
  ScopeVariables.clear();
  DeleteContainerPointers(CurrentFnArguments);
  UserVariables.clear();
  DbgValues.clear();
  AbstractVariables.clear();
  LabelsBeforeInsn.clear();
  LabelsAfterInsn.clear();
  PrevLabel = NULL;
}

/// recordSourceLine - Register a source line with debug info. Returns the
/// unique label that was emitted and which provides correspondence to
/// the source line list.
void DwarfDebug::recordSourceLine(unsigned Line, unsigned Col, const MDNode *S,
                                  unsigned Flags) {
  StringRef Fn;
  StringRef Dir;
  unsigned Src = 1;
  if (S) {
    DIDescriptor Scope(S);

    if (Scope.isCompileUnit()) {
      DICompileUnit CU(S);
      Fn = CU.getFilename();
      Dir = CU.getDirectory();
    } else if (Scope.isFile()) {
      DIFile F(S);
      Fn = F.getFilename();
      Dir = F.getDirectory();
    } else if (Scope.isSubprogram()) {
      DISubprogram SP(S);
      Fn = SP.getFilename();
      Dir = SP.getDirectory();
    } else if (Scope.isLexicalBlockFile()) {
      DILexicalBlockFile DBF(S);
      Fn = DBF.getFilename();
      Dir = DBF.getDirectory();
    } else if (Scope.isLexicalBlock()) {
      DILexicalBlock DB(S);
      Fn = DB.getFilename();
      Dir = DB.getDirectory();
    } else
      llvm_unreachable("Unexpected scope info");

    Src = GetOrCreateSourceID(Fn, Dir);
  }
  Asm->OutStreamer.EmitDwarfLocDirective(Src, Line, Col, Flags, 0, 0, Fn);
}

//===----------------------------------------------------------------------===//
// 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();

  // 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(Asm, 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() {
  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
         E = CUMap.end(); I != E; ++I) {
    // Compute size of compile unit header.
    unsigned Offset = 
      sizeof(int32_t) + // Length of Compilation Unit Info
      sizeof(int16_t) + // DWARF version number
      sizeof(int32_t) + // Offset Into Abbrev. Section
      sizeof(int8_t);   // Pointer Size (in bytes)
    computeSizeAndOffset(I->second->getCUDie(), Offset, true);
  }
}

/// EmitSectionLabels - Emit initial Dwarf sections with a label at
/// the start of each one.
void DwarfDebug::EmitSectionLabels() {
  const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();

  // Dwarf sections base addresses.
  DwarfInfoSectionSym =
    EmitSectionSym(Asm, TLOF.getDwarfInfoSection(), "section_info");
  DwarfAbbrevSectionSym =
    EmitSectionSym(Asm, TLOF.getDwarfAbbrevSection(), "section_abbrev");
  EmitSectionSym(Asm, TLOF.getDwarfARangesSection());

  if (const MCSection *MacroInfo = TLOF.getDwarfMacroInfoSection())
    EmitSectionSym(Asm, MacroInfo);

  EmitSectionSym(Asm, TLOF.getDwarfLineSection(), "section_line");
  EmitSectionSym(Asm, TLOF.getDwarfLocSection());
  EmitSectionSym(Asm, TLOF.getDwarfPubTypesSection());
  DwarfStrSectionSym =
    EmitSectionSym(Asm, TLOF.getDwarfStrSection(), "section_str");
  DwarfDebugRangeSectionSym = EmitSectionSym(Asm, TLOF.getDwarfRangesSection(),
                                             "debug_range");

  DwarfDebugLocSectionSym = EmitSectionSym(Asm, TLOF.getDwarfLocSection(),
                                           "section_debug_loc");

  TextSectionSym = EmitSectionSym(Asm, TLOF.getTextSection(), "text_begin");
  EmitSectionSym(Asm, TLOF.getDataSection());
}

/// emitDIE - Recursively 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->isVerbose())
    Asm->OutStreamer.AddComment("Abbrev [" + Twine(AbbrevNumber) + "] 0x" +
                                Twine::utohexstr(Die->getOffset()) + ":0x" +
                                Twine::utohexstr(Die->getSize()) + " " +
                                dwarf::TagString(Abbrev->getTag()));
  Asm->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->isVerbose())
      Asm->OutStreamer.AddComment(dwarf::AttributeString(Attr));

    switch (Attr) {
    case dwarf::DW_AT_abstract_origin: {
      DIEEntry *E = cast<DIEEntry>(Values[i]);
      DIE *Origin = E->getEntry();
      unsigned Addr = Origin->getOffset();
      Asm->EmitInt32(Addr);
      break;
    }
    case dwarf::DW_AT_ranges: {
      // DW_AT_range Value encodes offset in debug_range section.
      DIEInteger *V = cast<DIEInteger>(Values[i]);

      if (Asm->MAI->doesDwarfUseRelocationsAcrossSections()) {
        Asm->EmitLabelPlusOffset(DwarfDebugRangeSectionSym,
                                 V->getValue(),
                                 4);
      } else {
        Asm->EmitLabelOffsetDifference(DwarfDebugRangeSectionSym,
                                       V->getValue(),
                                       DwarfDebugRangeSectionSym,
                                       4);
      }
      break;
    }
    case dwarf::DW_AT_location: {
      if (DIELabel *L = dyn_cast<DIELabel>(Values[i])) {
        if (Asm->MAI->doesDwarfUseRelocationsAcrossSections())
          Asm->EmitLabelReference(L->getValue(), 4);
        else
          Asm->EmitLabelDifference(L->getValue(), DwarfDebugLocSectionSym, 4);
      } else {
        Values[i]->EmitValue(Asm, Form);
      }
      break;
    }
    case dwarf::DW_AT_accessibility: {
      if (Asm->isVerbose()) {
        DIEInteger *V = cast<DIEInteger>(Values[i]);
        Asm->OutStreamer.AddComment(dwarf::AccessibilityString(V->getValue()));
      }
      Values[i]->EmitValue(Asm, Form);
      break;
    }
    default:
      // Emit an attribute using the defined form.
      Values[i]->EmitValue(Asm, 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->isVerbose())
      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());
  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
         E = CUMap.end(); I != E; ++I) {
    CompileUnit *TheCU = I->second;
    DIE *Die = TheCU->getCUDie();

    // Emit the compile units header.
    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("info_begin",
                                                  TheCU->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)

    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");
    Asm->EmitSectionOffset(Asm->GetTempSymbol("abbrev_begin"),
                           DwarfAbbrevSectionSym);
    Asm->OutStreamer.AddComment("Address Size (in bytes)");
    Asm->EmitInt8(Asm->getDataLayout().getPointerSize());

    emitDIE(Die);
    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("info_end", TheCU->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(Asm->GetTempSymbol("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.)
      Asm->EmitULEB128(Abbrev->getNumber(), "Abbreviation Code");

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

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

    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("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(Asm->getDataLayout().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(Asm->GetTempSymbol("section_end",SectionEnd),
                                   Asm->getDataLayout().getPointerSize(),
                                   0/*AddrSpace*/);

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

/// emitAccelNames - Emit visible names into a hashed accelerator table
/// section.
void DwarfDebug::emitAccelNames() {
  DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
                                           dwarf::DW_FORM_data4));
  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
         E = CUMap.end(); I != E; ++I) {
    CompileUnit *TheCU = I->second;
    const StringMap<std::vector<DIE*> > &Names = TheCU->getAccelNames();
    for (StringMap<std::vector<DIE*> >::const_iterator
           GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
      const char *Name = GI->getKeyData();
      const std::vector<DIE *> &Entities = GI->second;
      for (std::vector<DIE *>::const_iterator DI = Entities.begin(),
             DE = Entities.end(); DI != DE; ++DI)
        AT.AddName(Name, (*DI));
    }
  }

  AT.FinalizeTable(Asm, "Names");
  Asm->OutStreamer.SwitchSection(
    Asm->getObjFileLowering().getDwarfAccelNamesSection());
  MCSymbol *SectionBegin = Asm->GetTempSymbol("names_begin");
  Asm->OutStreamer.EmitLabel(SectionBegin);

  // Emit the full data.
  AT.Emit(Asm, SectionBegin, this);
}

/// emitAccelObjC - Emit objective C classes and categories into a hashed
/// accelerator table section.
void DwarfDebug::emitAccelObjC() {
  DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
                                           dwarf::DW_FORM_data4));
  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
         E = CUMap.end(); I != E; ++I) {
    CompileUnit *TheCU = I->second;
    const StringMap<std::vector<DIE*> > &Names = TheCU->getAccelObjC();
    for (StringMap<std::vector<DIE*> >::const_iterator
           GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
      const char *Name = GI->getKeyData();
      const std::vector<DIE *> &Entities = GI->second;
      for (std::vector<DIE *>::const_iterator DI = Entities.begin(),
             DE = Entities.end(); DI != DE; ++DI)
        AT.AddName(Name, (*DI));
    }
  }

  AT.FinalizeTable(Asm, "ObjC");
  Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering()
                                 .getDwarfAccelObjCSection());
  MCSymbol *SectionBegin = Asm->GetTempSymbol("objc_begin");
  Asm->OutStreamer.EmitLabel(SectionBegin);

  // Emit the full data.
  AT.Emit(Asm, SectionBegin, this);
}

/// emitAccelNamespace - Emit namespace dies into a hashed accelerator
/// table.
void DwarfDebug::emitAccelNamespaces() {
  DwarfAccelTable AT(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
                                           dwarf::DW_FORM_data4));
  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
         E = CUMap.end(); I != E; ++I) {
    CompileUnit *TheCU = I->second;
    const StringMap<std::vector<DIE*> > &Names = TheCU->getAccelNamespace();
    for (StringMap<std::vector<DIE*> >::const_iterator
           GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
      const char *Name = GI->getKeyData();
      const std::vector<DIE *> &Entities = GI->second;
      for (std::vector<DIE *>::const_iterator DI = Entities.begin(),
             DE = Entities.end(); DI != DE; ++DI)
        AT.AddName(Name, (*DI));
    }
  }

  AT.FinalizeTable(Asm, "namespac");
  Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering()
                                 .getDwarfAccelNamespaceSection());
  MCSymbol *SectionBegin = Asm->GetTempSymbol("namespac_begin");
  Asm->OutStreamer.EmitLabel(SectionBegin);

  // Emit the full data.
  AT.Emit(Asm, SectionBegin, this);
}

/// emitAccelTypes() - Emit type dies into a hashed accelerator table.
void DwarfDebug::emitAccelTypes() {
  std::vector<DwarfAccelTable::Atom> Atoms;
  Atoms.push_back(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeDIEOffset,
                                        dwarf::DW_FORM_data4));
  Atoms.push_back(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeTag,
                                        dwarf::DW_FORM_data2));
  Atoms.push_back(DwarfAccelTable::Atom(DwarfAccelTable::eAtomTypeTypeFlags,
                                        dwarf::DW_FORM_data1));
  DwarfAccelTable AT(Atoms);
  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
         E = CUMap.end(); I != E; ++I) {
    CompileUnit *TheCU = I->second;
    const StringMap<std::vector<std::pair<DIE*, unsigned > > > &Names
      = TheCU->getAccelTypes();
    for (StringMap<std::vector<std::pair<DIE*, unsigned> > >::const_iterator
           GI = Names.begin(), GE = Names.end(); GI != GE; ++GI) {
      const char *Name = GI->getKeyData();
      const std::vector<std::pair<DIE *, unsigned> > &Entities = GI->second;
      for (std::vector<std::pair<DIE *, unsigned> >::const_iterator DI
             = Entities.begin(), DE = Entities.end(); DI !=DE; ++DI)
        AT.AddName(Name, (*DI).first, (*DI).second);
    }
  }

  AT.FinalizeTable(Asm, "types");
  Asm->OutStreamer.SwitchSection(Asm->getObjFileLowering()
                                 .getDwarfAccelTypesSection());
  MCSymbol *SectionBegin = Asm->GetTempSymbol("types_begin");
  Asm->OutStreamer.EmitLabel(SectionBegin);

  // Emit the full data.
  AT.Emit(Asm, SectionBegin, this);
}

void DwarfDebug::emitDebugPubTypes() {
  for (DenseMap<const MDNode *, CompileUnit *>::iterator I = CUMap.begin(),
         E = CUMap.end(); I != E; ++I) {
    CompileUnit *TheCU = I->second;
    // Start the dwarf pubtypes section.
    Asm->OutStreamer.SwitchSection(
      Asm->getObjFileLowering().getDwarfPubTypesSection());
    Asm->OutStreamer.AddComment("Length of Public Types Info");
    Asm->EmitLabelDifference(
      Asm->GetTempSymbol("pubtypes_end", TheCU->getID()),
      Asm->GetTempSymbol("pubtypes_begin", TheCU->getID()), 4);

    Asm->OutStreamer.EmitLabel(Asm->GetTempSymbol("pubtypes_begin",
                                                  TheCU->getID()));

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

    Asm->OutStreamer.AddComment("Offset of Compilation Unit Info");
    Asm->EmitSectionOffset(Asm->GetTempSymbol("info_begin", TheCU->getID()),
                           DwarfInfoSectionSym);

    Asm->OutStreamer.AddComment("Compilation Unit Length");
    Asm->EmitLabelDifference(Asm->GetTempSymbol("info_end", TheCU->getID()),
                             Asm->GetTempSymbol("info_begin", TheCU->getID()),
                             4);

    const StringMap<DIE*> &Globals = TheCU->getGlobalTypes();
    for (StringMap<DIE*>::const_iterator
           GI = Globals.begin(), GE = Globals.end(); GI != GE; ++GI) {