lib/MC/MCDwarf.cpp - fp2-dev/platform/external/llvm - Gitiles

 //===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
 //
 //                     The LLVM Compiler Infrastructure
 //
 // This file is distributed under the University of Illinois Open Source
 // License. See LICENSE.TXT for details.
 //
 //===----------------------------------------------------------------------===//

 #include "llvm/MC/MCAsmInfo.h"
 #include "llvm/MC/MCDwarf.h"
 #include "llvm/MC/MCAssembler.h"
 #include "llvm/MC/MCStreamer.h"
 #include "llvm/MC/MCSymbol.h"
 #include "llvm/MC/MCExpr.h"
 #include "llvm/MC/MCContext.h"
 #include "llvm/MC/MCObjectWriter.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Target/TargetAsmBackend.h"
 #include "llvm/Target/TargetAsmInfo.h"
 using namespace llvm;

 // Given a special op, return the address skip amount (in units of
 // DWARF2_LINE_MIN_INSN_LENGTH.
 #define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)

 // The maximum address skip amount that can be encoded with a special op.
 #define MAX_SPECIAL_ADDR_DELTA		SPECIAL_ADDR(255)

 // First special line opcode - leave room for the standard opcodes.
 // Note: If you want to change this, you'll have to update the
 // "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
 #define DWARF2_LINE_OPCODE_BASE		13

 // Minimum line offset in a special line info. opcode.  This value
 // was chosen to give a reasonable range of values.
 #define DWARF2_LINE_BASE		-5

 // Range of line offsets in a special line info. opcode.
 # define DWARF2_LINE_RANGE		14

 // Define the architecture-dependent minimum instruction length (in bytes).
 // This value should be rather too small than too big.
 # define DWARF2_LINE_MIN_INSN_LENGTH	1

 // Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
 // this routine is a nop and will be optimized away.
 static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta)
 {
   if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
     return AddrDelta;
   if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
     // TODO: report this error, but really only once.
     ;
   }
   return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
 }

 //
 // This is called when an instruction is assembled into the specified section
 // and if there is information from the last .loc directive that has yet to have
 // a line entry made for it is made.
 //
 void MCLineEntry::Make(MCStreamer *MCOS, const MCSection *Section) {
   if (!MCOS->getContext().getDwarfLocSeen())
     return;

   // Create a symbol at in the current section for use in the line entry.
   MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
   // Set the value of the symbol to use for the MCLineEntry.
   MCOS->EmitLabel(LineSym);

   // Get the current .loc info saved in the context.
   const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();

   // Create a (local) line entry with the symbol and the current .loc info.
   MCLineEntry LineEntry(LineSym, DwarfLoc);

   // clear DwarfLocSeen saying the current .loc info is now used.
   MCOS->getContext().ClearDwarfLocSeen();

   // Get the MCLineSection for this section, if one does not exist for this
   // section create it.
   const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
     MCOS->getContext().getMCLineSections();
   MCLineSection *LineSection = MCLineSections.lookup(Section);
   if (!LineSection) {
     // Create a new MCLineSection.  This will be deleted after the dwarf line
     // table is created using it by iterating through the MCLineSections
     // DenseMap.
     LineSection = new MCLineSection;
     // Save a pointer to the new LineSection into the MCLineSections DenseMap.
     MCOS->getContext().addMCLineSection(Section, LineSection);
   }

   // Add the line entry to this section's entries.
   LineSection->addLineEntry(LineEntry);
 }

 //
 // This helper routine returns an expression of End - Start + IntVal .
 //
 static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
                                                   const MCSymbol &Start,
                                                   const MCSymbol &End,
                                                   int IntVal) {
   MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
   const MCExpr *Res =
     MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
   const MCExpr *RHS =
     MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
   const MCExpr *Res1 =
     MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
   const MCExpr *Res2 =
     MCConstantExpr::Create(IntVal, MCOS.getContext());
   const MCExpr *Res3 =
     MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
   return Res3;
 }

 //
 // This emits the Dwarf line table for the specified section from the entries
 // in the LineSection.
 //
 static inline void EmitDwarfLineTable(MCStreamer *MCOS,
                                       const MCSection *Section,
                                       const MCLineSection *LineSection) {
   unsigned FileNum = 1;
   unsigned LastLine = 1;
   unsigned Column = 0;
   unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
   unsigned Isa = 0;
   MCSymbol *LastLabel = NULL;

   // Loop through each MCLineEntry and encode the dwarf line number table.
   for (MCLineSection::const_iterator
          it = LineSection->getMCLineEntries()->begin(),
          ie = LineSection->getMCLineEntries()->end(); it != ie; ++it) {

     if (FileNum != it->getFileNum()) {
       FileNum = it->getFileNum();
       MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
       MCOS->EmitULEB128IntValue(FileNum);
     }
     if (Column != it->getColumn()) {
       Column = it->getColumn();
       MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
       MCOS->EmitULEB128IntValue(Column);
     }
     if (Isa != it->getIsa()) {
       Isa = it->getIsa();
       MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
       MCOS->EmitULEB128IntValue(Isa);
     }
     if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
       Flags = it->getFlags();
       MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
     }
     if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
       MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
     if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
       MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
     if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
       MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);

     int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
     MCSymbol *Label = it->getLabel();

     // At this point we want to emit/create the sequence to encode the delta in
     // line numbers and the increment of the address from the previous Label
     // and the current Label.
     MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label);

     LastLine = it->getLine();
     LastLabel = Label;
   }

   // Emit a DW_LNE_end_sequence for the end of the section.
   // Using the pointer Section create a temporary label at the end of the
   // section and use that and the LastLabel to compute the address delta
   // and use INT64_MAX as the line delta which is the signal that this is
   // actually a DW_LNE_end_sequence.

   // Switch to the section to be able to create a symbol at its end.
   MCOS->SwitchSection(Section);

   MCContext &context = MCOS->getContext();
   // Create a symbol at the end of the section.
   MCSymbol *SectionEnd = context.CreateTempSymbol();
   // Set the value of the symbol, as we are at the end of the section.
   MCOS->EmitLabel(SectionEnd);

   // Switch back the the dwarf line section.
   MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());

   MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd);
 }

 //
 // This emits the Dwarf file and the line tables.
 //
 void MCDwarfFileTable::Emit(MCStreamer *MCOS) {
   MCContext &context = MCOS->getContext();
   // Switch to the section where the table will be emitted into.
   MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());

   // Create a symbol at the beginning of this section.
   MCSymbol *LineStartSym = context.CreateTempSymbol();
   // Set the value of the symbol, as we are at the start of the section.
   MCOS->EmitLabel(LineStartSym);

   // Create a symbol for the end of the section (to be set when we get there).
   MCSymbol *LineEndSym = context.CreateTempSymbol();

   // The first 4 bytes is the total length of the information for this
   // compilation unit (not including these 4 bytes for the length).
   MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *LineEndSym,4),
                      4);

   // Next 2 bytes is the Version, which is Dwarf 2.
   MCOS->EmitIntValue(2, 2);

   // Create a symbol for the end of the prologue (to be set when we get there).
   MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end

   // Length of the prologue, is the next 4 bytes.  Which is the start of the
   // section to the end of the prologue.  Not including the 4 bytes for the
   // total length, the 2 bytes for the version, and these 4 bytes for the
   // length of the prologue.
   MCOS->EmitAbsValue(MakeStartMinusEndExpr(*MCOS, *LineStartSym, *ProEndSym,
                                         (4 + 2 + 4)),
                   4, 0);

   // Parameters of the state machine, are next.
   MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
   MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
   MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
   MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
   MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);

   // Standard opcode lengths
   MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
   MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
   MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
   MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
   MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
   MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
   MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
   MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
   MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
   MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa

   // Put out the directory and file tables.

   // First the directory table.
   const std::vector<StringRef> &MCDwarfDirs =
     context.getMCDwarfDirs();
   for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
     MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
     MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
   }
   MCOS->EmitIntValue(0, 1); // Terminate the directory list

   // Second the file table.
   const std::vector<MCDwarfFile *> &MCDwarfFiles =
     MCOS->getContext().getMCDwarfFiles();
   for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
     MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
     MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
     // the Directory num
     MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex());
     MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
     MCOS->EmitIntValue(0, 1); // filesize (always 0)
   }
   MCOS->EmitIntValue(0, 1); // Terminate the file list

   // This is the end of the prologue, so set the value of the symbol at the
   // end of the prologue (that was used in a previous expression).
   MCOS->EmitLabel(ProEndSym);

   // Put out the line tables.
   const DenseMap<const MCSection *, MCLineSection *> &MCLineSections =
     MCOS->getContext().getMCLineSections();
   const std::vector<const MCSection *> &MCLineSectionOrder =
     MCOS->getContext().getMCLineSectionOrder();
   for (std::vector<const MCSection*>::const_iterator it =
 	MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie;
        ++it) {
     const MCSection *Sec = *it;
     const MCLineSection *Line = MCLineSections.lookup(Sec);
     EmitDwarfLineTable(MCOS, Sec, Line);

     // Now delete the MCLineSections that were created in MCLineEntry::Make()
     // and used to emit the line table.
     delete Line;
   }

   if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines()
       && MCLineSectionOrder.begin() == MCLineSectionOrder.end()) {
     // The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
     // it requires:
     // total_length >= prologue_length + 10
     // We are 4 bytes short, since we have total_length = 51 and
     // prologue_length = 45

     // The regular end_sequence should be sufficient.
     MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
   }

   // This is the end of the section, so set the value of the symbol at the end
   // of this section (that was used in a previous expression).
   MCOS->EmitLabel(LineEndSym);
 }

 /// Utility function to write the encoding to an object writer.
 void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
                             uint64_t AddrDelta) {
   SmallString<256> Tmp;
   raw_svector_ostream OS(Tmp);
   MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
   OW->WriteBytes(OS.str());
 }

 /// Utility function to emit the encoding to a streamer.
 void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
                            uint64_t AddrDelta) {
   SmallString<256> Tmp;
   raw_svector_ostream OS(Tmp);
   MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
   MCOS->EmitBytes(OS.str(), /*AddrSpace=*/0);
 }

 /// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
 void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
                              raw_ostream &OS) {
   uint64_t Temp, Opcode;
   bool NeedCopy = false;

   // Scale the address delta by the minimum instruction length.
   AddrDelta = ScaleAddrDelta(AddrDelta);

   // A LineDelta of INT64_MAX is a signal that this is actually a
   // DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
   // end_sequence to emit the matrix entry.
   if (LineDelta == INT64_MAX) {
     if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
       OS << char(dwarf::DW_LNS_const_add_pc);
     else {
       OS << char(dwarf::DW_LNS_advance_pc);
       SmallString<32> Tmp;
       raw_svector_ostream OSE(Tmp);
       MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
       OS << OSE.str();
     }
     OS << char(dwarf::DW_LNS_extended_op);
     OS << char(1);
     OS << char(dwarf::DW_LNE_end_sequence);
     return;
   }

   // Bias the line delta by the base.
   Temp = LineDelta - DWARF2_LINE_BASE;

   // If the line increment is out of range of a special opcode, we must encode
   // it with DW_LNS_advance_line.
   if (Temp >= DWARF2_LINE_RANGE) {
     OS << char(dwarf::DW_LNS_advance_line);
     SmallString<32> Tmp;
     raw_svector_ostream OSE(Tmp);
     MCObjectWriter::EncodeSLEB128(LineDelta, OSE);
     OS << OSE.str();

     LineDelta = 0;
     Temp = 0 - DWARF2_LINE_BASE;
     NeedCopy = true;
   }

   // Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
   if (LineDelta == 0 && AddrDelta == 0) {
     OS << char(dwarf::DW_LNS_copy);
     return;
   }

   // Bias the opcode by the special opcode base.
   Temp += DWARF2_LINE_OPCODE_BASE;

   // Avoid overflow when addr_delta is large.
   if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
     // Try using a special opcode.
     Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
     if (Opcode <= 255) {
       OS << char(Opcode);
       return;
     }

     // Try using DW_LNS_const_add_pc followed by special op.
     Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
     if (Opcode <= 255) {
       OS << char(dwarf::DW_LNS_const_add_pc);
       OS << char(Opcode);
       return;
     }
   }

   // Otherwise use DW_LNS_advance_pc.
   OS << char(dwarf::DW_LNS_advance_pc);
   SmallString<32> Tmp;
   raw_svector_ostream OSE(Tmp);
   MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
   OS << OSE.str();

   if (NeedCopy)
     OS << char(dwarf::DW_LNS_copy);
   else
     OS << char(Temp);
 }

 void MCDwarfFile::print(raw_ostream &OS) const {
   OS << '"' << getName() << '"';
 }

 void MCDwarfFile::dump() const {
   print(dbgs());
 }

 static int getDataAlignmentFactor(MCStreamer &streamer) {
   MCContext &context = streamer.getContext();
   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
   int size = asmInfo.getPointerSize();
   if (asmInfo.getStackGrowthDirection() == TargetFrameInfo::StackGrowsUp)
     return size;
  else
    return -size;
 }

 /// EmitFrameMoves - Emit frame instructions to describe the layout of the
 /// frame.
 static void EmitFrameMoves(MCStreamer &streamer,
                            const std::vector<MachineMove> &Moves,
                            MCSymbol *BaseLabel, bool isEH) {
   MCContext &context = streamer.getContext();
   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
   int dataAlignmentFactor = getDataAlignmentFactor(streamer);

   for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
     const MachineMove &Move = Moves[i];
     MCSymbol *Label = Move.getLabel();
     // Throw out move if the label is invalid.
     if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.

     const MachineLocation &Dst = Move.getDestination();
     const MachineLocation &Src = Move.getSource();

     // Advance row if new location.
     if (BaseLabel && Label) {
       MCSymbol *ThisSym = Label;
       if (ThisSym != BaseLabel) {
         streamer.EmitIntValue(dwarf::DW_CFA_advance_loc4, 1);
         const MCExpr *Length = MakeStartMinusEndExpr(streamer, *BaseLabel,
                                                      *ThisSym, 4);
         streamer.EmitValue(Length, 4);
         BaseLabel = ThisSym;
       }
     }

     // If advancing cfa.
     if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
       assert(!Src.isReg() && "Machine move not supported yet.");

       if (Src.getReg() == MachineLocation::VirtualFP) {
         streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
       } else {
         streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
         streamer.EmitULEB128IntValue(asmInfo.getDwarfRegNum(Src.getReg(), isEH),
                                      1);
       }

       streamer.EmitULEB128IntValue(-Src.getOffset(), 1);
       continue;
     }

     if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
       assert(Dst.isReg() && "Machine move not supported yet.");
       streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
       streamer.EmitULEB128IntValue(asmInfo.getDwarfRegNum(Dst.getReg(), isEH));
       continue;
     }

     unsigned Reg = asmInfo.getDwarfRegNum(Src.getReg(), isEH);
     int Offset = Dst.getOffset() / dataAlignmentFactor;

     if (Offset < 0) {
       streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
       streamer.EmitULEB128IntValue(Reg);
       streamer.EmitSLEB128IntValue(Offset);
     } else if (Reg < 64) {
       streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
       streamer.EmitULEB128IntValue(Offset, 1);
     } else {
       streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
       streamer.EmitULEB128IntValue(Reg, 1);
       streamer.EmitULEB128IntValue(Offset, 1);
     }
   }
 }

 static const MCSymbol &EmitCIE(MCStreamer &streamer) {
   MCContext &context = streamer.getContext();
   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
   const MCSection &section = *asmInfo.getEHFrameSection();
   streamer.SwitchSection(&section);
   MCSymbol *sectionStart = streamer.getContext().CreateTempSymbol();
   MCSymbol *sectionEnd = streamer.getContext().CreateTempSymbol();

   // Length
   const MCExpr *Length = MakeStartMinusEndExpr(streamer, *sectionStart,
                                                *sectionEnd, 4);
   streamer.EmitLabel(sectionStart);
   streamer.EmitValue(Length, 4);

   // CIE ID
   streamer.EmitIntValue(0, 4);

   // Version
   streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);

   // Augmentation String
   SmallString<8> Augmentation;
   Augmentation += "zR";
   streamer.EmitBytes(Augmentation.str(), 0);
   streamer.EmitIntValue(0, 1);

   // Code Alignment Factor
   streamer.EmitULEB128IntValue(1);

   // Data Alignment Factor
   streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));

   // Return Address Register
   streamer.EmitULEB128IntValue(asmInfo.getDwarfRARegNum(true));

   // Augmentation Data Length (optional)
   MCSymbol *augmentationStart = streamer.getContext().CreateTempSymbol();
   MCSymbol *augmentationEnd = streamer.getContext().CreateTempSymbol();
   const MCExpr *augmentationLength = MakeStartMinusEndExpr(streamer,
                                                            *augmentationStart,
                                                            *augmentationEnd, 0);
   streamer.EmitULEB128Value(augmentationLength);

   // Augmentation Data (optional)
   streamer.EmitLabel(augmentationStart);
   streamer.EmitIntValue(dwarf::DW_EH_PE_pcrel | dwarf::DW_EH_PE_sdata4, 1);
   streamer.EmitLabel(augmentationEnd);

   // Initial Instructions

   const std::vector<MachineMove> Moves = asmInfo.getInitialFrameState();

   EmitFrameMoves(streamer, Moves, NULL, true);

   // Padding
   streamer.EmitValueToAlignment(asmInfo.getPointerSize());

   streamer.EmitLabel(sectionEnd);
   return *sectionStart;
 }

 static MCSymbol *EmitFDE(MCStreamer &streamer,
                          const MCSymbol &cieStart,
                          const MCDwarfFrameInfo &frame) {
   MCSymbol *fdeStart = streamer.getContext().CreateTempSymbol();
   MCSymbol *fdeEnd = streamer.getContext().CreateTempSymbol();

   // Length
   const MCExpr *Length = MakeStartMinusEndExpr(streamer, *fdeStart, *fdeEnd, 0);
   streamer.EmitValue(Length, 4);

   streamer.EmitLabel(fdeStart);
   // CIE Pointer
   const MCExpr *offset = MakeStartMinusEndExpr(streamer, cieStart, *fdeStart,
                                                0);
   streamer.EmitValue(offset, 4);

   // PC Begin
   streamer.EmitPCRelSymbolValue(frame.Begin, 4);

   // PC Range
   const MCExpr *Range = MakeStartMinusEndExpr(streamer, *frame.Begin,
                                               *frame.End, 0);
   streamer.EmitValue(Range, 4);

   // Augmentation Data Length
   streamer.EmitULEB128IntValue(0);

   // Augmentation Data
   // Call Frame Instructions

   // Padding
   streamer.EmitValueToAlignment(4);

   return fdeEnd;
 }

 void MCDwarfFrameEmitter::Emit(MCStreamer &streamer) {
   const MCContext &context = streamer.getContext();
   const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
   const MCSymbol &cieStart = EmitCIE(streamer);
   MCSymbol *fdeEnd = NULL;
   for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
     fdeEnd = EmitFDE(streamer, cieStart, streamer.getFrameInfo(i));
     if (i != n - 1)
       streamer.EmitLabel(fdeEnd);
   }
   streamer.EmitValueToAlignment(asmInfo.getPointerSize());
   if (fdeEnd)
     streamer.EmitLabel(fdeEnd);
 }
	//===- lib/MC/MCDwarf.cpp - MCDwarf implementation ------------------------===//
	//
	// The LLVM Compiler Infrastructure
	//
	// This file is distributed under the University of Illinois Open Source
	// License. See LICENSE.TXT for details.
	//
	//===----------------------------------------------------------------------===//

	#include "llvm/MC/MCAsmInfo.h"
	#include "llvm/MC/MCDwarf.h"
	#include "llvm/MC/MCAssembler.h"
	#include "llvm/MC/MCStreamer.h"
	#include "llvm/MC/MCSymbol.h"
	#include "llvm/MC/MCExpr.h"
	#include "llvm/MC/MCContext.h"
	#include "llvm/MC/MCObjectWriter.h"
	#include "llvm/ADT/SmallString.h"
	#include "llvm/Support/Debug.h"
	#include "llvm/Support/raw_ostream.h"
	#include "llvm/Target/TargetAsmBackend.h"
	#include "llvm/Target/TargetAsmInfo.h"
	using namespace llvm;

	// Given a special op, return the address skip amount (in units of
	// DWARF2_LINE_MIN_INSN_LENGTH.
	#define SPECIAL_ADDR(op) (((op) - DWARF2_LINE_OPCODE_BASE)/DWARF2_LINE_RANGE)

	// The maximum address skip amount that can be encoded with a special op.
	#define MAX_SPECIAL_ADDR_DELTA SPECIAL_ADDR(255)

	// First special line opcode - leave room for the standard opcodes.
	// Note: If you want to change this, you'll have to update the
	// "standard_opcode_lengths" table that is emitted in DwarfFileTable::Emit().
	#define DWARF2_LINE_OPCODE_BASE 13

	// Minimum line offset in a special line info. opcode. This value
	// was chosen to give a reasonable range of values.
	#define DWARF2_LINE_BASE -5

	// Range of line offsets in a special line info. opcode.
	# define DWARF2_LINE_RANGE 14

	// Define the architecture-dependent minimum instruction length (in bytes).
	// This value should be rather too small than too big.
	# define DWARF2_LINE_MIN_INSN_LENGTH 1

	// Note: when DWARF2_LINE_MIN_INSN_LENGTH == 1 which is the current setting,
	// this routine is a nop and will be optimized away.
	static inline uint64_t ScaleAddrDelta(uint64_t AddrDelta)
	{
	if (DWARF2_LINE_MIN_INSN_LENGTH == 1)
	return AddrDelta;
	if (AddrDelta % DWARF2_LINE_MIN_INSN_LENGTH != 0) {
	// TODO: report this error, but really only once.
	;
	}
	return AddrDelta / DWARF2_LINE_MIN_INSN_LENGTH;
	}

	//
	// This is called when an instruction is assembled into the specified section
	// and if there is information from the last .loc directive that has yet to have
	// a line entry made for it is made.
	//
	void MCLineEntry::Make(MCStreamer MCOS, const MCSection Section) {
	if (!MCOS->getContext().getDwarfLocSeen())
	return;

	// Create a symbol at in the current section for use in the line entry.
	MCSymbol *LineSym = MCOS->getContext().CreateTempSymbol();
	// Set the value of the symbol to use for the MCLineEntry.
	MCOS->EmitLabel(LineSym);

	// Get the current .loc info saved in the context.
	const MCDwarfLoc &DwarfLoc = MCOS->getContext().getCurrentDwarfLoc();

	// Create a (local) line entry with the symbol and the current .loc info.
	MCLineEntry LineEntry(LineSym, DwarfLoc);

	// clear DwarfLocSeen saying the current .loc info is now used.
	MCOS->getContext().ClearDwarfLocSeen();

	// Get the MCLineSection for this section, if one does not exist for this
	// section create it.
	const DenseMap<const MCSection , MCLineSection > &MCLineSections =
	MCOS->getContext().getMCLineSections();
	MCLineSection *LineSection = MCLineSections.lookup(Section);
	if (!LineSection) {
	// Create a new MCLineSection. This will be deleted after the dwarf line
	// table is created using it by iterating through the MCLineSections
	// DenseMap.
	LineSection = new MCLineSection;
	// Save a pointer to the new LineSection into the MCLineSections DenseMap.
	MCOS->getContext().addMCLineSection(Section, LineSection);
	}

	// Add the line entry to this section's entries.
	LineSection->addLineEntry(LineEntry);
	}

	//
	// This helper routine returns an expression of End - Start + IntVal .
	//
	static inline const MCExpr *MakeStartMinusEndExpr(const MCStreamer &MCOS,
	const MCSymbol &Start,
	const MCSymbol &End,
	int IntVal) {
	MCSymbolRefExpr::VariantKind Variant = MCSymbolRefExpr::VK_None;
	const MCExpr *Res =
	MCSymbolRefExpr::Create(&End, Variant, MCOS.getContext());
	const MCExpr *RHS =
	MCSymbolRefExpr::Create(&Start, Variant, MCOS.getContext());
	const MCExpr *Res1 =
	MCBinaryExpr::Create(MCBinaryExpr::Sub, Res, RHS, MCOS.getContext());
	const MCExpr *Res2 =
	MCConstantExpr::Create(IntVal, MCOS.getContext());
	const MCExpr *Res3 =
	MCBinaryExpr::Create(MCBinaryExpr::Sub, Res1, Res2, MCOS.getContext());
	return Res3;
	}

	//
	// This emits the Dwarf line table for the specified section from the entries
	// in the LineSection.
	//
	static inline void EmitDwarfLineTable(MCStreamer *MCOS,
	const MCSection *Section,
	const MCLineSection *LineSection) {
	unsigned FileNum = 1;
	unsigned LastLine = 1;
	unsigned Column = 0;
	unsigned Flags = DWARF2_LINE_DEFAULT_IS_STMT ? DWARF2_FLAG_IS_STMT : 0;
	unsigned Isa = 0;
	MCSymbol *LastLabel = NULL;

	// Loop through each MCLineEntry and encode the dwarf line number table.
	for (MCLineSection::const_iterator
	it = LineSection->getMCLineEntries()->begin(),
	ie = LineSection->getMCLineEntries()->end(); it != ie; ++it) {

	if (FileNum != it->getFileNum()) {
	FileNum = it->getFileNum();
	MCOS->EmitIntValue(dwarf::DW_LNS_set_file, 1);
	MCOS->EmitULEB128IntValue(FileNum);
	}
	if (Column != it->getColumn()) {
	Column = it->getColumn();
	MCOS->EmitIntValue(dwarf::DW_LNS_set_column, 1);
	MCOS->EmitULEB128IntValue(Column);
	}
	if (Isa != it->getIsa()) {
	Isa = it->getIsa();
	MCOS->EmitIntValue(dwarf::DW_LNS_set_isa, 1);
	MCOS->EmitULEB128IntValue(Isa);
	}
	if ((it->getFlags() ^ Flags) & DWARF2_FLAG_IS_STMT) {
	Flags = it->getFlags();
	MCOS->EmitIntValue(dwarf::DW_LNS_negate_stmt, 1);
	}
	if (it->getFlags() & DWARF2_FLAG_BASIC_BLOCK)
	MCOS->EmitIntValue(dwarf::DW_LNS_set_basic_block, 1);
	if (it->getFlags() & DWARF2_FLAG_PROLOGUE_END)
	MCOS->EmitIntValue(dwarf::DW_LNS_set_prologue_end, 1);
	if (it->getFlags() & DWARF2_FLAG_EPILOGUE_BEGIN)
	MCOS->EmitIntValue(dwarf::DW_LNS_set_epilogue_begin, 1);

	int64_t LineDelta = static_cast<int64_t>(it->getLine()) - LastLine;
	MCSymbol *Label = it->getLabel();

	// At this point we want to emit/create the sequence to encode the delta in
	// line numbers and the increment of the address from the previous Label
	// and the current Label.
	MCOS->EmitDwarfAdvanceLineAddr(LineDelta, LastLabel, Label);

	LastLine = it->getLine();
	LastLabel = Label;
	}

	// Emit a DW_LNE_end_sequence for the end of the section.
	// Using the pointer Section create a temporary label at the end of the
	// section and use that and the LastLabel to compute the address delta
	// and use INT64_MAX as the line delta which is the signal that this is
	// actually a DW_LNE_end_sequence.

	// Switch to the section to be able to create a symbol at its end.
	MCOS->SwitchSection(Section);

	MCContext &context = MCOS->getContext();
	// Create a symbol at the end of the section.
	MCSymbol *SectionEnd = context.CreateTempSymbol();
	// Set the value of the symbol, as we are at the end of the section.
	MCOS->EmitLabel(SectionEnd);

	// Switch back the the dwarf line section.
	MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());

	MCOS->EmitDwarfAdvanceLineAddr(INT64_MAX, LastLabel, SectionEnd);
	}

	//
	// This emits the Dwarf file and the line tables.
	//
	void MCDwarfFileTable::Emit(MCStreamer *MCOS) {
	MCContext &context = MCOS->getContext();
	// Switch to the section where the table will be emitted into.
	MCOS->SwitchSection(context.getTargetAsmInfo().getDwarfLineSection());

	// Create a symbol at the beginning of this section.
	MCSymbol *LineStartSym = context.CreateTempSymbol();
	// Set the value of the symbol, as we are at the start of the section.
	MCOS->EmitLabel(LineStartSym);

	// Create a symbol for the end of the section (to be set when we get there).
	MCSymbol *LineEndSym = context.CreateTempSymbol();

	// The first 4 bytes is the total length of the information for this
	// compilation unit (not including these 4 bytes for the length).
	MCOS->EmitAbsValue(MakeStartMinusEndExpr(MCOS, LineStartSym, *LineEndSym,4),
	4);

	// Next 2 bytes is the Version, which is Dwarf 2.
	MCOS->EmitIntValue(2, 2);

	// Create a symbol for the end of the prologue (to be set when we get there).
	MCSymbol *ProEndSym = context.CreateTempSymbol(); // Lprologue_end

	// Length of the prologue, is the next 4 bytes. Which is the start of the
	// section to the end of the prologue. Not including the 4 bytes for the
	// total length, the 2 bytes for the version, and these 4 bytes for the
	// length of the prologue.
	MCOS->EmitAbsValue(MakeStartMinusEndExpr(MCOS, LineStartSym, *ProEndSym,
	(4 + 2 + 4)),
	4, 0);

	// Parameters of the state machine, are next.
	MCOS->EmitIntValue(DWARF2_LINE_MIN_INSN_LENGTH, 1);
	MCOS->EmitIntValue(DWARF2_LINE_DEFAULT_IS_STMT, 1);
	MCOS->EmitIntValue(DWARF2_LINE_BASE, 1);
	MCOS->EmitIntValue(DWARF2_LINE_RANGE, 1);
	MCOS->EmitIntValue(DWARF2_LINE_OPCODE_BASE, 1);

	// Standard opcode lengths
	MCOS->EmitIntValue(0, 1); // length of DW_LNS_copy
	MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_pc
	MCOS->EmitIntValue(1, 1); // length of DW_LNS_advance_line
	MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_file
	MCOS->EmitIntValue(1, 1); // length of DW_LNS_set_column
	MCOS->EmitIntValue(0, 1); // length of DW_LNS_negate_stmt
	MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_basic_block
	MCOS->EmitIntValue(0, 1); // length of DW_LNS_const_add_pc
	MCOS->EmitIntValue(1, 1); // length of DW_LNS_fixed_advance_pc
	MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_prologue_end
	MCOS->EmitIntValue(0, 1); // length of DW_LNS_set_epilogue_begin
	MCOS->EmitIntValue(1, 1); // DW_LNS_set_isa

	// Put out the directory and file tables.

	// First the directory table.
	const std::vector<StringRef> &MCDwarfDirs =
	context.getMCDwarfDirs();
	for (unsigned i = 0; i < MCDwarfDirs.size(); i++) {
	MCOS->EmitBytes(MCDwarfDirs[i], 0); // the DirectoryName
	MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
	}
	MCOS->EmitIntValue(0, 1); // Terminate the directory list

	// Second the file table.
	const std::vector<MCDwarfFile *> &MCDwarfFiles =
	MCOS->getContext().getMCDwarfFiles();
	for (unsigned i = 1; i < MCDwarfFiles.size(); i++) {
	MCOS->EmitBytes(MCDwarfFiles[i]->getName(), 0); // FileName
	MCOS->EmitBytes(StringRef("\0", 1), 0); // the null term. of the string
	// the Directory num
	MCOS->EmitULEB128IntValue(MCDwarfFiles[i]->getDirIndex());
	MCOS->EmitIntValue(0, 1); // last modification timestamp (always 0)
	MCOS->EmitIntValue(0, 1); // filesize (always 0)
	}
	MCOS->EmitIntValue(0, 1); // Terminate the file list

	// This is the end of the prologue, so set the value of the symbol at the
	// end of the prologue (that was used in a previous expression).
	MCOS->EmitLabel(ProEndSym);

	// Put out the line tables.
	const DenseMap<const MCSection , MCLineSection > &MCLineSections =
	MCOS->getContext().getMCLineSections();
	const std::vector<const MCSection *> &MCLineSectionOrder =
	MCOS->getContext().getMCLineSectionOrder();
	for (std::vector<const MCSection*>::const_iterator it =
	MCLineSectionOrder.begin(), ie = MCLineSectionOrder.end(); it != ie;
	++it) {
	const MCSection Sec = it;
	const MCLineSection *Line = MCLineSections.lookup(Sec);
	EmitDwarfLineTable(MCOS, Sec, Line);

	// Now delete the MCLineSections that were created in MCLineEntry::Make()
	// and used to emit the line table.
	delete Line;
	}

	if (MCOS->getContext().getAsmInfo().getLinkerRequiresNonEmptyDwarfLines()
	&& MCLineSectionOrder.begin() == MCLineSectionOrder.end()) {
	// The darwin9 linker has a bug (see PR8715). For for 32-bit architectures
	// it requires:
	// total_length >= prologue_length + 10
	// We are 4 bytes short, since we have total_length = 51 and
	// prologue_length = 45

	// The regular end_sequence should be sufficient.
	MCDwarfLineAddr::Emit(MCOS, INT64_MAX, 0);
	}

	// This is the end of the section, so set the value of the symbol at the end
	// of this section (that was used in a previous expression).
	MCOS->EmitLabel(LineEndSym);
	}

	/// Utility function to write the encoding to an object writer.
	void MCDwarfLineAddr::Write(MCObjectWriter *OW, int64_t LineDelta,
	uint64_t AddrDelta) {
	SmallString<256> Tmp;
	raw_svector_ostream OS(Tmp);
	MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
	OW->WriteBytes(OS.str());
	}

	/// Utility function to emit the encoding to a streamer.
	void MCDwarfLineAddr::Emit(MCStreamer *MCOS, int64_t LineDelta,
	uint64_t AddrDelta) {
	SmallString<256> Tmp;
	raw_svector_ostream OS(Tmp);
	MCDwarfLineAddr::Encode(LineDelta, AddrDelta, OS);
	MCOS->EmitBytes(OS.str(), /AddrSpace=/0);
	}

	/// Utility function to encode a Dwarf pair of LineDelta and AddrDeltas.
	void MCDwarfLineAddr::Encode(int64_t LineDelta, uint64_t AddrDelta,
	raw_ostream &OS) {
	uint64_t Temp, Opcode;
	bool NeedCopy = false;

	// Scale the address delta by the minimum instruction length.
	AddrDelta = ScaleAddrDelta(AddrDelta);

	// A LineDelta of INT64_MAX is a signal that this is actually a
	// DW_LNE_end_sequence. We cannot use special opcodes here, since we want the
	// end_sequence to emit the matrix entry.
	if (LineDelta == INT64_MAX) {
	if (AddrDelta == MAX_SPECIAL_ADDR_DELTA)
	OS << char(dwarf::DW_LNS_const_add_pc);
	else {
	OS << char(dwarf::DW_LNS_advance_pc);
	SmallString<32> Tmp;
	raw_svector_ostream OSE(Tmp);
	MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
	OS << OSE.str();
	}
	OS << char(dwarf::DW_LNS_extended_op);
	OS << char(1);
	OS << char(dwarf::DW_LNE_end_sequence);
	return;
	}

	// Bias the line delta by the base.
	Temp = LineDelta - DWARF2_LINE_BASE;

	// If the line increment is out of range of a special opcode, we must encode
	// it with DW_LNS_advance_line.
	if (Temp >= DWARF2_LINE_RANGE) {
	OS << char(dwarf::DW_LNS_advance_line);
	SmallString<32> Tmp;
	raw_svector_ostream OSE(Tmp);
	MCObjectWriter::EncodeSLEB128(LineDelta, OSE);
	OS << OSE.str();

	LineDelta = 0;
	Temp = 0 - DWARF2_LINE_BASE;
	NeedCopy = true;
	}

	// Use DW_LNS_copy instead of a "line +0, addr +0" special opcode.
	if (LineDelta == 0 && AddrDelta == 0) {
	OS << char(dwarf::DW_LNS_copy);
	return;
	}

	// Bias the opcode by the special opcode base.
	Temp += DWARF2_LINE_OPCODE_BASE;

	// Avoid overflow when addr_delta is large.
	if (AddrDelta < 256 + MAX_SPECIAL_ADDR_DELTA) {
	// Try using a special opcode.
	Opcode = Temp + AddrDelta * DWARF2_LINE_RANGE;
	if (Opcode <= 255) {
	OS << char(Opcode);
	return;
	}

	// Try using DW_LNS_const_add_pc followed by special op.
	Opcode = Temp + (AddrDelta - MAX_SPECIAL_ADDR_DELTA) * DWARF2_LINE_RANGE;
	if (Opcode <= 255) {
	OS << char(dwarf::DW_LNS_const_add_pc);
	OS << char(Opcode);
	return;
	}
	}

	// Otherwise use DW_LNS_advance_pc.
	OS << char(dwarf::DW_LNS_advance_pc);
	SmallString<32> Tmp;
	raw_svector_ostream OSE(Tmp);
	MCObjectWriter::EncodeULEB128(AddrDelta, OSE);
	OS << OSE.str();

	if (NeedCopy)
	OS << char(dwarf::DW_LNS_copy);
	else
	OS << char(Temp);
	}

	void MCDwarfFile::print(raw_ostream &OS) const {
	OS << '"' << getName() << '"';
	}

	void MCDwarfFile::dump() const {
	print(dbgs());
	}

	static int getDataAlignmentFactor(MCStreamer &streamer) {
	MCContext &context = streamer.getContext();
	const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
	int size = asmInfo.getPointerSize();
	if (asmInfo.getStackGrowthDirection() == TargetFrameInfo::StackGrowsUp)
	return size;
	else
	return -size;
	}

	/// EmitFrameMoves - Emit frame instructions to describe the layout of the
	/// frame.
	static void EmitFrameMoves(MCStreamer &streamer,
	const std::vector<MachineMove> &Moves,
	MCSymbol *BaseLabel, bool isEH) {
	MCContext &context = streamer.getContext();
	const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
	int dataAlignmentFactor = getDataAlignmentFactor(streamer);

	for (unsigned i = 0, N = Moves.size(); i < N; ++i) {
	const MachineMove &Move = Moves[i];
	MCSymbol *Label = Move.getLabel();
	// Throw out move if the label is invalid.
	if (Label && !Label->isDefined()) continue; // Not emitted, in dead code.

	const MachineLocation &Dst = Move.getDestination();
	const MachineLocation &Src = Move.getSource();

	// Advance row if new location.
	if (BaseLabel && Label) {
	MCSymbol *ThisSym = Label;
	if (ThisSym != BaseLabel) {
	streamer.EmitIntValue(dwarf::DW_CFA_advance_loc4, 1);
	const MCExpr Length = MakeStartMinusEndExpr(streamer, BaseLabel,
	*ThisSym, 4);
	streamer.EmitValue(Length, 4);
	BaseLabel = ThisSym;
	}
	}

	// If advancing cfa.
	if (Dst.isReg() && Dst.getReg() == MachineLocation::VirtualFP) {
	assert(!Src.isReg() && "Machine move not supported yet.");

	if (Src.getReg() == MachineLocation::VirtualFP) {
	streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_offset, 1);
	} else {
	streamer.EmitIntValue(dwarf::DW_CFA_def_cfa, 1);
	streamer.EmitULEB128IntValue(asmInfo.getDwarfRegNum(Src.getReg(), isEH),
	1);
	}

	streamer.EmitULEB128IntValue(-Src.getOffset(), 1);
	continue;
	}

	if (Src.isReg() && Src.getReg() == MachineLocation::VirtualFP) {
	assert(Dst.isReg() && "Machine move not supported yet.");
	streamer.EmitIntValue(dwarf::DW_CFA_def_cfa_register, 1);
	streamer.EmitULEB128IntValue(asmInfo.getDwarfRegNum(Dst.getReg(), isEH));
	continue;
	}

	unsigned Reg = asmInfo.getDwarfRegNum(Src.getReg(), isEH);
	int Offset = Dst.getOffset() / dataAlignmentFactor;

	if (Offset < 0) {
	streamer.EmitIntValue(dwarf::DW_CFA_offset_extended_sf, 1);
	streamer.EmitULEB128IntValue(Reg);
	streamer.EmitSLEB128IntValue(Offset);
	} else if (Reg < 64) {
	streamer.EmitIntValue(dwarf::DW_CFA_offset + Reg, 1);
	streamer.EmitULEB128IntValue(Offset, 1);
	} else {
	streamer.EmitIntValue(dwarf::DW_CFA_offset_extended, 1);
	streamer.EmitULEB128IntValue(Reg, 1);
	streamer.EmitULEB128IntValue(Offset, 1);
	}
	}
	}

	static const MCSymbol &EmitCIE(MCStreamer &streamer) {
	MCContext &context = streamer.getContext();
	const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
	const MCSection &section = *asmInfo.getEHFrameSection();
	streamer.SwitchSection(&section);
	MCSymbol *sectionStart = streamer.getContext().CreateTempSymbol();
	MCSymbol *sectionEnd = streamer.getContext().CreateTempSymbol();

	// Length
	const MCExpr Length = MakeStartMinusEndExpr(streamer, sectionStart,
	*sectionEnd, 4);
	streamer.EmitLabel(sectionStart);
	streamer.EmitValue(Length, 4);

	// CIE ID
	streamer.EmitIntValue(0, 4);

	// Version
	streamer.EmitIntValue(dwarf::DW_CIE_VERSION, 1);

	// Augmentation String
	SmallString<8> Augmentation;
	Augmentation += "zR";
	streamer.EmitBytes(Augmentation.str(), 0);
	streamer.EmitIntValue(0, 1);

	// Code Alignment Factor
	streamer.EmitULEB128IntValue(1);

	// Data Alignment Factor
	streamer.EmitSLEB128IntValue(getDataAlignmentFactor(streamer));

	// Return Address Register
	streamer.EmitULEB128IntValue(asmInfo.getDwarfRARegNum(true));

	// Augmentation Data Length (optional)
	MCSymbol *augmentationStart = streamer.getContext().CreateTempSymbol();
	MCSymbol *augmentationEnd = streamer.getContext().CreateTempSymbol();
	const MCExpr *augmentationLength = MakeStartMinusEndExpr(streamer,
	*augmentationStart,
	*augmentationEnd, 0);
	streamer.EmitULEB128Value(augmentationLength);

	// Augmentation Data (optional)
	streamer.EmitLabel(augmentationStart);
	streamer.EmitIntValue(dwarf::DW_EH_PE_pcrel \| dwarf::DW_EH_PE_sdata4, 1);
	streamer.EmitLabel(augmentationEnd);

	// Initial Instructions

	const std::vector<MachineMove> Moves = asmInfo.getInitialFrameState();

	EmitFrameMoves(streamer, Moves, NULL, true);

	// Padding
	streamer.EmitValueToAlignment(asmInfo.getPointerSize());

	streamer.EmitLabel(sectionEnd);
	return *sectionStart;
	}

	static MCSymbol *EmitFDE(MCStreamer &streamer,
	const MCSymbol &cieStart,
	const MCDwarfFrameInfo &frame) {
	MCSymbol *fdeStart = streamer.getContext().CreateTempSymbol();
	MCSymbol *fdeEnd = streamer.getContext().CreateTempSymbol();

	// Length
	const MCExpr Length = MakeStartMinusEndExpr(streamer, fdeStart, *fdeEnd, 0);
	streamer.EmitValue(Length, 4);

	streamer.EmitLabel(fdeStart);
	// CIE Pointer
	const MCExpr offset = MakeStartMinusEndExpr(streamer, cieStart, fdeStart,
	0);
	streamer.EmitValue(offset, 4);

	// PC Begin
	streamer.EmitPCRelSymbolValue(frame.Begin, 4);

	// PC Range
	const MCExpr Range = MakeStartMinusEndExpr(streamer, frame.Begin,
	*frame.End, 0);
	streamer.EmitValue(Range, 4);

	// Augmentation Data Length
	streamer.EmitULEB128IntValue(0);

	// Augmentation Data
	// Call Frame Instructions

	// Padding
	streamer.EmitValueToAlignment(4);

	return fdeEnd;
	}

	void MCDwarfFrameEmitter::Emit(MCStreamer &streamer) {
	const MCContext &context = streamer.getContext();
	const TargetAsmInfo &asmInfo = context.getTargetAsmInfo();
	const MCSymbol &cieStart = EmitCIE(streamer);
	MCSymbol *fdeEnd = NULL;
	for (unsigned i = 0, n = streamer.getNumFrameInfos(); i < n; ++i) {
	fdeEnd = EmitFDE(streamer, cieStart, streamer.getFrameInfo(i));
	if (i != n - 1)
	streamer.EmitLabel(fdeEnd);
	}
	streamer.EmitValueToAlignment(asmInfo.getPointerSize());
	if (fdeEnd)
	streamer.EmitLabel(fdeEnd);
	}