llvm/lib/ObjectYAML/DWARFEmitter.cpp - toolchain/llvm-project - Gitiles

 //===- DWARFEmitter - Convert YAML to DWARF binary data -------------------===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 ///
 /// \file
 /// The DWARF component of yaml2obj. Provided as library code for tests.
 ///
 //===----------------------------------------------------------------------===//

 #include "llvm/ObjectYAML/DWARFEmitter.h"
 #include "DWARFVisitor.h"
 #include "llvm/ADT/StringMap.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/ObjectYAML/DWARFYAML.h"
 #include "llvm/Support/Error.h"
 #include "llvm/Support/Host.h"
 #include "llvm/Support/LEB128.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/SwapByteOrder.h"
 #include "llvm/Support/YAMLTraits.h"
 #include "llvm/Support/raw_ostream.h"
 #include <algorithm>
 #include <cassert>
 #include <cstddef>
 #include <cstdint>
 #include <memory>
 #include <string>
 #include <vector>

 using namespace llvm;

 template <typename T>
 static void writeInteger(T Integer, raw_ostream &OS, bool IsLittleEndian) {
   if (IsLittleEndian != sys::IsLittleEndianHost)
     sys::swapByteOrder(Integer);
   OS.write(reinterpret_cast<char *>(&Integer), sizeof(T));
 }

 static void writeVariableSizedInteger(uint64_t Integer, size_t Size,
                                       raw_ostream &OS, bool IsLittleEndian) {
   if (8 == Size)
     writeInteger((uint64_t)Integer, OS, IsLittleEndian);
   else if (4 == Size)
     writeInteger((uint32_t)Integer, OS, IsLittleEndian);
   else if (2 == Size)
     writeInteger((uint16_t)Integer, OS, IsLittleEndian);
   else if (1 == Size)
     writeInteger((uint8_t)Integer, OS, IsLittleEndian);
   else
     assert(false && "Invalid integer write size.");
 }

 static void ZeroFillBytes(raw_ostream &OS, size_t Size) {
   std::vector<uint8_t> FillData;
   FillData.insert(FillData.begin(), Size, 0);
   OS.write(reinterpret_cast<char *>(FillData.data()), Size);
 }

 static void writeInitialLength(const DWARFYAML::InitialLength &Length,
                                raw_ostream &OS, bool IsLittleEndian) {
   writeInteger((uint32_t)Length.TotalLength, OS, IsLittleEndian);
   if (Length.isDWARF64())
     writeInteger((uint64_t)Length.TotalLength64, OS, IsLittleEndian);
 }

 void DWARFYAML::EmitDebugStr(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (auto Str : DI.DebugStrings) {
     OS.write(Str.data(), Str.size());
     OS.write('\0');
   }
 }

 void DWARFYAML::EmitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (auto AbbrevDecl : DI.AbbrevDecls) {
     encodeULEB128(AbbrevDecl.Code, OS);
     encodeULEB128(AbbrevDecl.Tag, OS);
     OS.write(AbbrevDecl.Children);
     for (auto Attr : AbbrevDecl.Attributes) {
       encodeULEB128(Attr.Attribute, OS);
       encodeULEB128(Attr.Form, OS);
       if (Attr.Form == dwarf::DW_FORM_implicit_const)
         encodeSLEB128(Attr.Value, OS);
     }
     encodeULEB128(0, OS);
     encodeULEB128(0, OS);
   }
 }

 void DWARFYAML::EmitDebugAranges(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (auto Range : DI.ARanges) {
     auto HeaderStart = OS.tell();
     writeInitialLength(Range.Length, OS, DI.IsLittleEndian);
     writeInteger((uint16_t)Range.Version, OS, DI.IsLittleEndian);
     writeInteger((uint32_t)Range.CuOffset, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)Range.AddrSize, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)Range.SegSize, OS, DI.IsLittleEndian);

     auto HeaderSize = OS.tell() - HeaderStart;
     auto FirstDescriptor = alignTo(HeaderSize, Range.AddrSize * 2);
     ZeroFillBytes(OS, FirstDescriptor - HeaderSize);

     for (auto Descriptor : Range.Descriptors) {
       writeVariableSizedInteger(Descriptor.Address, Range.AddrSize, OS,
                                 DI.IsLittleEndian);
       writeVariableSizedInteger(Descriptor.Length, Range.AddrSize, OS,
                                 DI.IsLittleEndian);
     }
     ZeroFillBytes(OS, Range.AddrSize * 2);
   }
 }

 void DWARFYAML::EmitPubSection(raw_ostream &OS,
                                const DWARFYAML::PubSection &Sect,
                                bool IsLittleEndian) {
   writeInitialLength(Sect.Length, OS, IsLittleEndian);
   writeInteger((uint16_t)Sect.Version, OS, IsLittleEndian);
   writeInteger((uint32_t)Sect.UnitOffset, OS, IsLittleEndian);
   writeInteger((uint32_t)Sect.UnitSize, OS, IsLittleEndian);
   for (auto Entry : Sect.Entries) {
     writeInteger((uint32_t)Entry.DieOffset, OS, IsLittleEndian);
     if (Sect.IsGNUStyle)
       writeInteger((uint32_t)Entry.Descriptor, OS, IsLittleEndian);
     OS.write(Entry.Name.data(), Entry.Name.size());
     OS.write('\0');
   }
 }

 namespace {
 /// An extension of the DWARFYAML::ConstVisitor which writes compile
 /// units and DIEs to a stream.
 class DumpVisitor : public DWARFYAML::ConstVisitor {
   raw_ostream &OS;

 protected:
   void onStartCompileUnit(const DWARFYAML::Unit &CU) override {
     writeInitialLength(CU.Length, OS, DebugInfo.IsLittleEndian);
     writeInteger((uint16_t)CU.Version, OS, DebugInfo.IsLittleEndian);
     if(CU.Version >= 5) {
       writeInteger((uint8_t)CU.Type, OS, DebugInfo.IsLittleEndian);
       writeInteger((uint8_t)CU.AddrSize, OS, DebugInfo.IsLittleEndian);
       writeInteger((uint32_t)CU.AbbrOffset, OS, DebugInfo.IsLittleEndian);
     }else {
       writeInteger((uint32_t)CU.AbbrOffset, OS, DebugInfo.IsLittleEndian);
       writeInteger((uint8_t)CU.AddrSize, OS, DebugInfo.IsLittleEndian);
     }
   }

   void onStartDIE(const DWARFYAML::Unit &CU,
                   const DWARFYAML::Entry &DIE) override {
     encodeULEB128(DIE.AbbrCode, OS);
   }

   void onValue(const uint8_t U) override {
     writeInteger(U, OS, DebugInfo.IsLittleEndian);
   }

   void onValue(const uint16_t U) override {
     writeInteger(U, OS, DebugInfo.IsLittleEndian);
   }

   void onValue(const uint32_t U) override {
     writeInteger(U, OS, DebugInfo.IsLittleEndian);
   }

   void onValue(const uint64_t U, const bool LEB = false) override {
     if (LEB)
       encodeULEB128(U, OS);
     else
       writeInteger(U, OS, DebugInfo.IsLittleEndian);
   }

   void onValue(const int64_t S, const bool LEB = false) override {
     if (LEB)
       encodeSLEB128(S, OS);
     else
       writeInteger(S, OS, DebugInfo.IsLittleEndian);
   }

   void onValue(const StringRef String) override {
     OS.write(String.data(), String.size());
     OS.write('\0');
   }

   void onValue(const MemoryBufferRef MBR) override {
     OS.write(MBR.getBufferStart(), MBR.getBufferSize());
   }

 public:
   DumpVisitor(const DWARFYAML::Data &DI, raw_ostream &Out)
       : DWARFYAML::ConstVisitor(DI), OS(Out) {}
 };
 } // namespace

 void DWARFYAML::EmitDebugInfo(raw_ostream &OS, const DWARFYAML::Data &DI) {
   DumpVisitor Visitor(DI, OS);
   Visitor.traverseDebugInfo();
 }

 static void EmitFileEntry(raw_ostream &OS, const DWARFYAML::File &File) {
   OS.write(File.Name.data(), File.Name.size());
   OS.write('\0');
   encodeULEB128(File.DirIdx, OS);
   encodeULEB128(File.ModTime, OS);
   encodeULEB128(File.Length, OS);
 }

 void DWARFYAML::EmitDebugLine(raw_ostream &OS, const DWARFYAML::Data &DI) {
   for (const auto &LineTable : DI.DebugLines) {
     writeInitialLength(LineTable.Length, OS, DI.IsLittleEndian);
     uint64_t SizeOfPrologueLength = LineTable.Length.isDWARF64() ? 8 : 4;
     writeInteger((uint16_t)LineTable.Version, OS, DI.IsLittleEndian);
     writeVariableSizedInteger(LineTable.PrologueLength, SizeOfPrologueLength,
                               OS, DI.IsLittleEndian);
     writeInteger((uint8_t)LineTable.MinInstLength, OS, DI.IsLittleEndian);
     if (LineTable.Version >= 4)
       writeInteger((uint8_t)LineTable.MaxOpsPerInst, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)LineTable.DefaultIsStmt, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)LineTable.LineBase, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)LineTable.LineRange, OS, DI.IsLittleEndian);
     writeInteger((uint8_t)LineTable.OpcodeBase, OS, DI.IsLittleEndian);

     for (auto OpcodeLength : LineTable.StandardOpcodeLengths)
       writeInteger((uint8_t)OpcodeLength, OS, DI.IsLittleEndian);

     for (auto IncludeDir : LineTable.IncludeDirs) {
       OS.write(IncludeDir.data(), IncludeDir.size());
       OS.write('\0');
     }
     OS.write('\0');

     for (auto File : LineTable.Files)
       EmitFileEntry(OS, File);
     OS.write('\0');

     for (auto Op : LineTable.Opcodes) {
       writeInteger((uint8_t)Op.Opcode, OS, DI.IsLittleEndian);
       if (Op.Opcode == 0) {
         encodeULEB128(Op.ExtLen, OS);
         writeInteger((uint8_t)Op.SubOpcode, OS, DI.IsLittleEndian);
         switch (Op.SubOpcode) {
         case dwarf::DW_LNE_set_address:
         case dwarf::DW_LNE_set_discriminator:
           writeVariableSizedInteger(Op.Data, DI.CompileUnits[0].AddrSize, OS,
                                     DI.IsLittleEndian);
           break;
         case dwarf::DW_LNE_define_file:
           EmitFileEntry(OS, Op.FileEntry);
           break;
         case dwarf::DW_LNE_end_sequence:
           break;
         default:
           for (auto OpByte : Op.UnknownOpcodeData)
             writeInteger((uint8_t)OpByte, OS, DI.IsLittleEndian);
         }
       } else if (Op.Opcode < LineTable.OpcodeBase) {
         switch (Op.Opcode) {
         case dwarf::DW_LNS_copy:
         case dwarf::DW_LNS_negate_stmt:
         case dwarf::DW_LNS_set_basic_block:
         case dwarf::DW_LNS_const_add_pc:
         case dwarf::DW_LNS_set_prologue_end:
         case dwarf::DW_LNS_set_epilogue_begin:
           break;

         case dwarf::DW_LNS_advance_pc:
         case dwarf::DW_LNS_set_file:
         case dwarf::DW_LNS_set_column:
         case dwarf::DW_LNS_set_isa:
           encodeULEB128(Op.Data, OS);
           break;

         case dwarf::DW_LNS_advance_line:
           encodeSLEB128(Op.SData, OS);
           break;

         case dwarf::DW_LNS_fixed_advance_pc:
           writeInteger((uint16_t)Op.Data, OS, DI.IsLittleEndian);
           break;

         default:
           for (auto OpData : Op.StandardOpcodeData) {
             encodeULEB128(OpData, OS);
           }
         }
       }
     }
   }
 }

 using EmitFuncType = void (*)(raw_ostream &, const DWARFYAML::Data &);

 static void
 EmitDebugSectionImpl(const DWARFYAML::Data &DI, EmitFuncType EmitFunc,
                      StringRef Sec,
                      StringMap<std::unique_ptr<MemoryBuffer>> &OutputBuffers) {
   std::string Data;
   raw_string_ostream DebugInfoStream(Data);
   EmitFunc(DebugInfoStream, DI);
   DebugInfoStream.flush();
   if (!Data.empty())
     OutputBuffers[Sec] = MemoryBuffer::getMemBufferCopy(Data);
 }

 namespace {
 class DIEFixupVisitor : public DWARFYAML::Visitor {
   uint64_t Length;

 public:
   DIEFixupVisitor(DWARFYAML::Data &DI) : DWARFYAML::Visitor(DI){};

 private:
   virtual void onStartCompileUnit(DWARFYAML::Unit &CU) { Length = 7; }

   virtual void onEndCompileUnit(DWARFYAML::Unit &CU) {
     CU.Length.setLength(Length);
   }

   virtual void onStartDIE(DWARFYAML::Unit &CU, DWARFYAML::Entry &DIE) {
     Length += getULEB128Size(DIE.AbbrCode);
   }

   virtual void onValue(const uint8_t U) { Length += 1; }
   virtual void onValue(const uint16_t U) { Length += 2; }
   virtual void onValue(const uint32_t U) { Length += 4; }
   virtual void onValue(const uint64_t U, const bool LEB = false) {
     if (LEB)
       Length += getULEB128Size(U);
     else
       Length += 8;
   }
   virtual void onValue(const int64_t S, const bool LEB = false) {
     if (LEB)
       Length += getSLEB128Size(S);
     else
       Length += 8;
   }
   virtual void onValue(const StringRef String) { Length += String.size() + 1; }

   virtual void onValue(const MemoryBufferRef MBR) {
     Length += MBR.getBufferSize();
   }
 };
 } // namespace

 Expected<StringMap<std::unique_ptr<MemoryBuffer>>>
 DWARFYAML::EmitDebugSections(StringRef YAMLString, bool ApplyFixups,
                              bool IsLittleEndian) {
   yaml::Input YIn(YAMLString);

   DWARFYAML::Data DI;
   DI.IsLittleEndian = IsLittleEndian;
   YIn >> DI;
   if (YIn.error())
     return errorCodeToError(YIn.error());

   if (ApplyFixups) {
     DIEFixupVisitor DIFixer(DI);
     DIFixer.traverseDebugInfo();
   }

   StringMap<std::unique_ptr<MemoryBuffer>> DebugSections;
   EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugInfo, "debug_info",
                        DebugSections);
   EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugLine, "debug_line",
                        DebugSections);
   EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugStr, "debug_str",
                        DebugSections);
   EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugAbbrev, "debug_abbrev",
                        DebugSections);
   EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugAranges, "debug_aranges",
                        DebugSections);
   return std::move(DebugSections);
 }
	//===- DWARFEmitter - Convert YAML to DWARF binary data -------------------===//
	//
	// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
	// See https://llvm.org/LICENSE.txt for license information.
	// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
	//
	//===----------------------------------------------------------------------===//
	///
	/// \file
	/// The DWARF component of yaml2obj. Provided as library code for tests.
	///
	//===----------------------------------------------------------------------===//

	#include "llvm/ObjectYAML/DWARFEmitter.h"
	#include "DWARFVisitor.h"
	#include "llvm/ADT/StringMap.h"
	#include "llvm/ADT/StringRef.h"
	#include "llvm/ObjectYAML/DWARFYAML.h"
	#include "llvm/Support/Error.h"
	#include "llvm/Support/Host.h"
	#include "llvm/Support/LEB128.h"
	#include "llvm/Support/MathExtras.h"
	#include "llvm/Support/MemoryBuffer.h"
	#include "llvm/Support/SwapByteOrder.h"
	#include "llvm/Support/YAMLTraits.h"
	#include "llvm/Support/raw_ostream.h"
	#include <algorithm>
	#include <cassert>
	#include <cstddef>
	#include <cstdint>
	#include <memory>
	#include <string>
	#include <vector>

	using namespace llvm;

	template <typename T>
	static void writeInteger(T Integer, raw_ostream &OS, bool IsLittleEndian) {
	if (IsLittleEndian != sys::IsLittleEndianHost)
	sys::swapByteOrder(Integer);
	OS.write(reinterpret_cast<char *>(&Integer), sizeof(T));
	}

	static void writeVariableSizedInteger(uint64_t Integer, size_t Size,
	raw_ostream &OS, bool IsLittleEndian) {
	if (8 == Size)
	writeInteger((uint64_t)Integer, OS, IsLittleEndian);
	else if (4 == Size)
	writeInteger((uint32_t)Integer, OS, IsLittleEndian);
	else if (2 == Size)
	writeInteger((uint16_t)Integer, OS, IsLittleEndian);
	else if (1 == Size)
	writeInteger((uint8_t)Integer, OS, IsLittleEndian);
	else
	assert(false && "Invalid integer write size.");
	}

	static void ZeroFillBytes(raw_ostream &OS, size_t Size) {
	std::vector<uint8_t> FillData;
	FillData.insert(FillData.begin(), Size, 0);
	OS.write(reinterpret_cast<char *>(FillData.data()), Size);
	}

	static void writeInitialLength(const DWARFYAML::InitialLength &Length,
	raw_ostream &OS, bool IsLittleEndian) {
	writeInteger((uint32_t)Length.TotalLength, OS, IsLittleEndian);
	if (Length.isDWARF64())
	writeInteger((uint64_t)Length.TotalLength64, OS, IsLittleEndian);
	}

	void DWARFYAML::EmitDebugStr(raw_ostream &OS, const DWARFYAML::Data &DI) {
	for (auto Str : DI.DebugStrings) {
	OS.write(Str.data(), Str.size());
	OS.write('\0');
	}
	}

	void DWARFYAML::EmitDebugAbbrev(raw_ostream &OS, const DWARFYAML::Data &DI) {
	for (auto AbbrevDecl : DI.AbbrevDecls) {
	encodeULEB128(AbbrevDecl.Code, OS);
	encodeULEB128(AbbrevDecl.Tag, OS);
	OS.write(AbbrevDecl.Children);
	for (auto Attr : AbbrevDecl.Attributes) {
	encodeULEB128(Attr.Attribute, OS);
	encodeULEB128(Attr.Form, OS);
	if (Attr.Form == dwarf::DW_FORM_implicit_const)
	encodeSLEB128(Attr.Value, OS);
	}
	encodeULEB128(0, OS);
	encodeULEB128(0, OS);
	}
	}

	void DWARFYAML::EmitDebugAranges(raw_ostream &OS, const DWARFYAML::Data &DI) {
	for (auto Range : DI.ARanges) {
	auto HeaderStart = OS.tell();
	writeInitialLength(Range.Length, OS, DI.IsLittleEndian);
	writeInteger((uint16_t)Range.Version, OS, DI.IsLittleEndian);
	writeInteger((uint32_t)Range.CuOffset, OS, DI.IsLittleEndian);
	writeInteger((uint8_t)Range.AddrSize, OS, DI.IsLittleEndian);
	writeInteger((uint8_t)Range.SegSize, OS, DI.IsLittleEndian);

	auto HeaderSize = OS.tell() - HeaderStart;
	auto FirstDescriptor = alignTo(HeaderSize, Range.AddrSize * 2);
	ZeroFillBytes(OS, FirstDescriptor - HeaderSize);

	for (auto Descriptor : Range.Descriptors) {
	writeVariableSizedInteger(Descriptor.Address, Range.AddrSize, OS,
	DI.IsLittleEndian);
	writeVariableSizedInteger(Descriptor.Length, Range.AddrSize, OS,
	DI.IsLittleEndian);
	}
	ZeroFillBytes(OS, Range.AddrSize * 2);
	}
	}

	void DWARFYAML::EmitPubSection(raw_ostream &OS,
	const DWARFYAML::PubSection &Sect,
	bool IsLittleEndian) {
	writeInitialLength(Sect.Length, OS, IsLittleEndian);
	writeInteger((uint16_t)Sect.Version, OS, IsLittleEndian);
	writeInteger((uint32_t)Sect.UnitOffset, OS, IsLittleEndian);
	writeInteger((uint32_t)Sect.UnitSize, OS, IsLittleEndian);
	for (auto Entry : Sect.Entries) {
	writeInteger((uint32_t)Entry.DieOffset, OS, IsLittleEndian);
	if (Sect.IsGNUStyle)
	writeInteger((uint32_t)Entry.Descriptor, OS, IsLittleEndian);
	OS.write(Entry.Name.data(), Entry.Name.size());
	OS.write('\0');
	}
	}

	namespace {
	/// An extension of the DWARFYAML::ConstVisitor which writes compile
	/// units and DIEs to a stream.
	class DumpVisitor : public DWARFYAML::ConstVisitor {
	raw_ostream &OS;

	protected:
	void onStartCompileUnit(const DWARFYAML::Unit &CU) override {
	writeInitialLength(CU.Length, OS, DebugInfo.IsLittleEndian);
	writeInteger((uint16_t)CU.Version, OS, DebugInfo.IsLittleEndian);
	if(CU.Version >= 5) {
	writeInteger((uint8_t)CU.Type, OS, DebugInfo.IsLittleEndian);
	writeInteger((uint8_t)CU.AddrSize, OS, DebugInfo.IsLittleEndian);
	writeInteger((uint32_t)CU.AbbrOffset, OS, DebugInfo.IsLittleEndian);
	}else {
	writeInteger((uint32_t)CU.AbbrOffset, OS, DebugInfo.IsLittleEndian);
	writeInteger((uint8_t)CU.AddrSize, OS, DebugInfo.IsLittleEndian);
	}
	}

	void onStartDIE(const DWARFYAML::Unit &CU,
	const DWARFYAML::Entry &DIE) override {
	encodeULEB128(DIE.AbbrCode, OS);
	}

	void onValue(const uint8_t U) override {
	writeInteger(U, OS, DebugInfo.IsLittleEndian);
	}

	void onValue(const uint16_t U) override {
	writeInteger(U, OS, DebugInfo.IsLittleEndian);
	}

	void onValue(const uint32_t U) override {
	writeInteger(U, OS, DebugInfo.IsLittleEndian);
	}

	void onValue(const uint64_t U, const bool LEB = false) override {
	if (LEB)
	encodeULEB128(U, OS);
	else
	writeInteger(U, OS, DebugInfo.IsLittleEndian);
	}

	void onValue(const int64_t S, const bool LEB = false) override {
	if (LEB)
	encodeSLEB128(S, OS);
	else
	writeInteger(S, OS, DebugInfo.IsLittleEndian);
	}

	void onValue(const StringRef String) override {
	OS.write(String.data(), String.size());
	OS.write('\0');
	}

	void onValue(const MemoryBufferRef MBR) override {
	OS.write(MBR.getBufferStart(), MBR.getBufferSize());
	}

	public:
	DumpVisitor(const DWARFYAML::Data &DI, raw_ostream &Out)
	: DWARFYAML::ConstVisitor(DI), OS(Out) {}
	};
	} // namespace

	void DWARFYAML::EmitDebugInfo(raw_ostream &OS, const DWARFYAML::Data &DI) {
	DumpVisitor Visitor(DI, OS);
	Visitor.traverseDebugInfo();
	}

	static void EmitFileEntry(raw_ostream &OS, const DWARFYAML::File &File) {
	OS.write(File.Name.data(), File.Name.size());
	OS.write('\0');
	encodeULEB128(File.DirIdx, OS);
	encodeULEB128(File.ModTime, OS);
	encodeULEB128(File.Length, OS);
	}

	void DWARFYAML::EmitDebugLine(raw_ostream &OS, const DWARFYAML::Data &DI) {
	for (const auto &LineTable : DI.DebugLines) {
	writeInitialLength(LineTable.Length, OS, DI.IsLittleEndian);
	uint64_t SizeOfPrologueLength = LineTable.Length.isDWARF64() ? 8 : 4;
	writeInteger((uint16_t)LineTable.Version, OS, DI.IsLittleEndian);
	writeVariableSizedInteger(LineTable.PrologueLength, SizeOfPrologueLength,
	OS, DI.IsLittleEndian);
	writeInteger((uint8_t)LineTable.MinInstLength, OS, DI.IsLittleEndian);
	if (LineTable.Version >= 4)
	writeInteger((uint8_t)LineTable.MaxOpsPerInst, OS, DI.IsLittleEndian);
	writeInteger((uint8_t)LineTable.DefaultIsStmt, OS, DI.IsLittleEndian);
	writeInteger((uint8_t)LineTable.LineBase, OS, DI.IsLittleEndian);
	writeInteger((uint8_t)LineTable.LineRange, OS, DI.IsLittleEndian);
	writeInteger((uint8_t)LineTable.OpcodeBase, OS, DI.IsLittleEndian);

	for (auto OpcodeLength : LineTable.StandardOpcodeLengths)
	writeInteger((uint8_t)OpcodeLength, OS, DI.IsLittleEndian);

	for (auto IncludeDir : LineTable.IncludeDirs) {
	OS.write(IncludeDir.data(), IncludeDir.size());
	OS.write('\0');
	}
	OS.write('\0');

	for (auto File : LineTable.Files)
	EmitFileEntry(OS, File);
	OS.write('\0');

	for (auto Op : LineTable.Opcodes) {
	writeInteger((uint8_t)Op.Opcode, OS, DI.IsLittleEndian);
	if (Op.Opcode == 0) {
	encodeULEB128(Op.ExtLen, OS);
	writeInteger((uint8_t)Op.SubOpcode, OS, DI.IsLittleEndian);
	switch (Op.SubOpcode) {
	case dwarf::DW_LNE_set_address:
	case dwarf::DW_LNE_set_discriminator:
	writeVariableSizedInteger(Op.Data, DI.CompileUnits[0].AddrSize, OS,
	DI.IsLittleEndian);
	break;
	case dwarf::DW_LNE_define_file:
	EmitFileEntry(OS, Op.FileEntry);
	break;
	case dwarf::DW_LNE_end_sequence:
	break;
	default:
	for (auto OpByte : Op.UnknownOpcodeData)
	writeInteger((uint8_t)OpByte, OS, DI.IsLittleEndian);
	}
	} else if (Op.Opcode < LineTable.OpcodeBase) {
	switch (Op.Opcode) {
	case dwarf::DW_LNS_copy:
	case dwarf::DW_LNS_negate_stmt:
	case dwarf::DW_LNS_set_basic_block:
	case dwarf::DW_LNS_const_add_pc:
	case dwarf::DW_LNS_set_prologue_end:
	case dwarf::DW_LNS_set_epilogue_begin:
	break;

	case dwarf::DW_LNS_advance_pc:
	case dwarf::DW_LNS_set_file:
	case dwarf::DW_LNS_set_column:
	case dwarf::DW_LNS_set_isa:
	encodeULEB128(Op.Data, OS);
	break;

	case dwarf::DW_LNS_advance_line:
	encodeSLEB128(Op.SData, OS);
	break;

	case dwarf::DW_LNS_fixed_advance_pc:
	writeInteger((uint16_t)Op.Data, OS, DI.IsLittleEndian);
	break;

	default:
	for (auto OpData : Op.StandardOpcodeData) {
	encodeULEB128(OpData, OS);
	}
	}
	}
	}
	}
	}

	using EmitFuncType = void (*)(raw_ostream &, const DWARFYAML::Data &);

	static void
	EmitDebugSectionImpl(const DWARFYAML::Data &DI, EmitFuncType EmitFunc,
	StringRef Sec,
	StringMap<std::unique_ptr<MemoryBuffer>> &OutputBuffers) {
	std::string Data;
	raw_string_ostream DebugInfoStream(Data);
	EmitFunc(DebugInfoStream, DI);
	DebugInfoStream.flush();
	if (!Data.empty())
	OutputBuffers[Sec] = MemoryBuffer::getMemBufferCopy(Data);
	}

	namespace {
	class DIEFixupVisitor : public DWARFYAML::Visitor {
	uint64_t Length;

	public:
	DIEFixupVisitor(DWARFYAML::Data &DI) : DWARFYAML::Visitor(DI){};

	private:
	virtual void onStartCompileUnit(DWARFYAML::Unit &CU) { Length = 7; }

	virtual void onEndCompileUnit(DWARFYAML::Unit &CU) {
	CU.Length.setLength(Length);
	}

	virtual void onStartDIE(DWARFYAML::Unit &CU, DWARFYAML::Entry &DIE) {
	Length += getULEB128Size(DIE.AbbrCode);
	}

	virtual void onValue(const uint8_t U) { Length += 1; }
	virtual void onValue(const uint16_t U) { Length += 2; }
	virtual void onValue(const uint32_t U) { Length += 4; }
	virtual void onValue(const uint64_t U, const bool LEB = false) {
	if (LEB)
	Length += getULEB128Size(U);
	else
	Length += 8;
	}
	virtual void onValue(const int64_t S, const bool LEB = false) {
	if (LEB)
	Length += getSLEB128Size(S);
	else
	Length += 8;
	}
	virtual void onValue(const StringRef String) { Length += String.size() + 1; }

	virtual void onValue(const MemoryBufferRef MBR) {
	Length += MBR.getBufferSize();
	}
	};
	} // namespace

	Expected<StringMap<std::unique_ptr<MemoryBuffer>>>
	DWARFYAML::EmitDebugSections(StringRef YAMLString, bool ApplyFixups,
	bool IsLittleEndian) {
	yaml::Input YIn(YAMLString);

	DWARFYAML::Data DI;
	DI.IsLittleEndian = IsLittleEndian;
	YIn >> DI;
	if (YIn.error())
	return errorCodeToError(YIn.error());

	if (ApplyFixups) {
	DIEFixupVisitor DIFixer(DI);
	DIFixer.traverseDebugInfo();
	}

	StringMap<std::unique_ptr<MemoryBuffer>> DebugSections;
	EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugInfo, "debug_info",
	DebugSections);
	EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugLine, "debug_line",
	DebugSections);
	EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugStr, "debug_str",
	DebugSections);
	EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugAbbrev, "debug_abbrev",
	DebugSections);
	EmitDebugSectionImpl(DI, &DWARFYAML::EmitDebugAranges, "debug_aranges",
	DebugSections);
	return std::move(DebugSections);
	}