C++ DWARFDataExtractor::getU8方法代码示例

llvm::Error DWARFDebugNames::Header::extract(const DWARFDataExtractor &AS,
                                             uint32_t *Offset) {
  // Check that we can read the fixed-size part.
  if (!AS.isValidOffset(*Offset + sizeof(HeaderPOD) - 1))
    return make_error<StringError>("Section too small: cannot read header.",
                                   inconvertibleErrorCode());

  UnitLength = AS.getU32(Offset);
  Version = AS.getU16(Offset);
  Padding = AS.getU16(Offset);
  CompUnitCount = AS.getU32(Offset);
  LocalTypeUnitCount = AS.getU32(Offset);
  ForeignTypeUnitCount = AS.getU32(Offset);
  BucketCount = AS.getU32(Offset);
  NameCount = AS.getU32(Offset);
  AbbrevTableSize = AS.getU32(Offset);
  AugmentationStringSize = AS.getU32(Offset);

  if (!AS.isValidOffsetForDataOfSize(*Offset, AugmentationStringSize))
    return make_error<StringError>(
        "Section too small: cannot read header augmentation.",
        inconvertibleErrorCode());
  AugmentationString.resize(AugmentationStringSize);
  AS.getU8(Offset, reinterpret_cast<uint8_t *>(AugmentationString.data()),
           AugmentationStringSize);
  *Offset = alignTo(*Offset, 4);
  return Error::success();
}

// Parse v5 directory/file entry content descriptions.
// Returns the descriptors, or an empty vector if we did not find a path or
// ran off the end of the prologue.
static ContentDescriptors
parseV5EntryFormat(const DWARFDataExtractor &DebugLineData, uint32_t *OffsetPtr,
                   uint64_t EndPrologueOffset, bool *HasMD5) {
  ContentDescriptors Descriptors;
  int FormatCount = DebugLineData.getU8(OffsetPtr);
  bool HasPath = false;
  for (int I = 0; I != FormatCount; ++I) {
    if (*OffsetPtr >= EndPrologueOffset)
      return ContentDescriptors();
    ContentDescriptor Descriptor;
    Descriptor.Type =
      dwarf::LineNumberEntryFormat(DebugLineData.getULEB128(OffsetPtr));
    Descriptor.Form = dwarf::Form(DebugLineData.getULEB128(OffsetPtr));
    if (Descriptor.Type == dwarf::DW_LNCT_path)
      HasPath = true;
    else if (Descriptor.Type == dwarf::DW_LNCT_MD5 && HasMD5)
      *HasMD5 = true;
    Descriptors.push_back(Descriptor);
  }
  return HasPath ? Descriptors : ContentDescriptors();
}

bool DWARFVerifier::verifyUnitHeader(const DWARFDataExtractor DebugInfoData,
                                     uint32_t *Offset, unsigned UnitIndex,
                                     uint8_t &UnitType, bool &isUnitDWARF64) {
  uint32_t AbbrOffset, Length;
  uint8_t AddrSize = 0;
  uint16_t Version;
  bool Success = true;

  bool ValidLength = false;
  bool ValidVersion = false;
  bool ValidAddrSize = false;
  bool ValidType = true;
  bool ValidAbbrevOffset = true;

  uint32_t OffsetStart = *Offset;
  Length = DebugInfoData.getU32(Offset);
  if (Length == UINT32_MAX) {
    isUnitDWARF64 = true;
    OS << format(
        "Unit[%d] is in 64-bit DWARF format; cannot verify from this point.\n",
        UnitIndex);
    return false;
  }
  Version = DebugInfoData.getU16(Offset);

  if (Version >= 5) {
    UnitType = DebugInfoData.getU8(Offset);
    AddrSize = DebugInfoData.getU8(Offset);
    AbbrOffset = DebugInfoData.getU32(Offset);
    ValidType = dwarf::isUnitType(UnitType);
  } else {
    UnitType = 0;
    AbbrOffset = DebugInfoData.getU32(Offset);
    AddrSize = DebugInfoData.getU8(Offset);
  }

  if (!DCtx.getDebugAbbrev()->getAbbreviationDeclarationSet(AbbrOffset))
    ValidAbbrevOffset = false;

  ValidLength = DebugInfoData.isValidOffset(OffsetStart + Length + 3);
  ValidVersion = DWARFContext::isSupportedVersion(Version);
  ValidAddrSize = AddrSize == 4 || AddrSize == 8;
  if (!ValidLength || !ValidVersion || !ValidAddrSize || !ValidAbbrevOffset ||
      !ValidType) {
    Success = false;
    error() << format("Units[%d] - start offset: 0x%08x \n", UnitIndex,
                      OffsetStart);
    if (!ValidLength)
      note() << "The length for this unit is too "
            "large for the .debug_info provided.\n";
    if (!ValidVersion)
      note() << "The 16 bit unit header version is not valid.\n";
    if (!ValidType)
      note() << "The unit type encoding is not valid.\n";
    if (!ValidAbbrevOffset)
      note() << "The offset into the .debug_abbrev section is "
            "not valid.\n";
    if (!ValidAddrSize)
      note() << "The address size is unsupported.\n";
  }
  *Offset = OffsetStart + Length + 4;
  return Success;
}

bool DWARFFormValue::extractValue(const DWARFDataExtractor &Data,
                                  uint32_t *OffsetPtr, DWARFFormParams FP,
                                  const DWARFUnit *CU) {
  U = CU;
  bool Indirect = false;
  bool IsBlock = false;
  Value.data = nullptr;
  // Read the value for the form into value and follow and DW_FORM_indirect
  // instances we run into
  do {
    Indirect = false;
    switch (Form) {
    case DW_FORM_addr:
    case DW_FORM_ref_addr: {
      uint16_t Size =
          (Form == DW_FORM_addr) ? FP.AddrSize : FP.getRefAddrByteSize();
      Value.uval = Data.getRelocatedValue(Size, OffsetPtr, &Value.SectionIndex);
      break;
    }
    case DW_FORM_exprloc:
    case DW_FORM_block:
      Value.uval = Data.getULEB128(OffsetPtr);
      IsBlock = true;
      break;
    case DW_FORM_block1:
      Value.uval = Data.getU8(OffsetPtr);
      IsBlock = true;
      break;
    case DW_FORM_block2:
      Value.uval = Data.getU16(OffsetPtr);
      IsBlock = true;
      break;
    case DW_FORM_block4:
      Value.uval = Data.getU32(OffsetPtr);
      IsBlock = true;
      break;
    case DW_FORM_data1:
    case DW_FORM_ref1:
    case DW_FORM_flag:
    case DW_FORM_strx1:
    case DW_FORM_addrx1:
      Value.uval = Data.getU8(OffsetPtr);
      break;
    case DW_FORM_data2:
    case DW_FORM_ref2:
    case DW_FORM_strx2:
    case DW_FORM_addrx2:
      Value.uval = Data.getU16(OffsetPtr);
      break;
    case DW_FORM_strx3:
      Value.uval = Data.getU24(OffsetPtr);
      break;
    case DW_FORM_data4:
    case DW_FORM_ref4:
    case DW_FORM_ref_sup4:
    case DW_FORM_strx4:
    case DW_FORM_addrx4:
      Value.uval = Data.getRelocatedValue(4, OffsetPtr);
      break;
    case DW_FORM_data8:
    case DW_FORM_ref8:
    case DW_FORM_ref_sup8:
      Value.uval = Data.getU64(OffsetPtr);
      break;
    case DW_FORM_data16:
      // Treat this like a 16-byte block.
      Value.uval = 16;
      IsBlock = true;
      break;
    case DW_FORM_sdata:
      Value.sval = Data.getSLEB128(OffsetPtr);
      break;
    case DW_FORM_udata:
    case DW_FORM_ref_udata:
      Value.uval = Data.getULEB128(OffsetPtr);
      break;
    case DW_FORM_string:
      Value.cstr = Data.getCStr(OffsetPtr);
      break;
    case DW_FORM_indirect:
      Form = static_cast<dwarf::Form>(Data.getULEB128(OffsetPtr));
      Indirect = true;
      break;
    case DW_FORM_strp:
    case DW_FORM_sec_offset:
    case DW_FORM_GNU_ref_alt:
    case DW_FORM_GNU_strp_alt:
    case DW_FORM_line_strp:
    case DW_FORM_strp_sup: {
      Value.uval =
          Data.getRelocatedValue(FP.getDwarfOffsetByteSize(), OffsetPtr);
      break;
    }
    case DW_FORM_flag_present:
      Value.uval = 1;
      break;
    case DW_FORM_ref_sig8:
      Value.uval = Data.getU64(OffsetPtr);
      break;
    case DW_FORM_GNU_addr_index:
//.........这里部分代码省略.........

bool DWARFUnitHeader::extract(DWARFContext &Context,
                              const DWARFDataExtractor &debug_info,
                              uint32_t *offset_ptr,
                              DWARFSectionKind SectionKind,
                              const DWARFUnitIndex *Index) {
  Offset = *offset_ptr;
  IndexEntry = Index ? Index->getFromOffset(*offset_ptr) : nullptr;
  Length = debug_info.getU32(offset_ptr);
  // FIXME: Support DWARF64.
  unsigned SizeOfLength = 4;
  FormParams.Format = DWARF32;
  FormParams.Version = debug_info.getU16(offset_ptr);
  if (FormParams.Version >= 5) {
    UnitType = debug_info.getU8(offset_ptr);
    FormParams.AddrSize = debug_info.getU8(offset_ptr);
    AbbrOffset = debug_info.getU32(offset_ptr);
  } else {
    AbbrOffset = debug_info.getRelocatedValue(4, offset_ptr);
    FormParams.AddrSize = debug_info.getU8(offset_ptr);
    // Fake a unit type based on the section type.  This isn't perfect,
    // but distinguishing compile and type units is generally enough.
    if (SectionKind == DW_SECT_TYPES)
      UnitType = DW_UT_type;
    else
      UnitType = DW_UT_compile;
  }
  if (IndexEntry) {
    if (AbbrOffset)
      return false;
    auto *UnitContrib = IndexEntry->getOffset();
    if (!UnitContrib || UnitContrib->Length != (Length + 4))
      return false;
    auto *AbbrEntry = IndexEntry->getOffset(DW_SECT_ABBREV);
    if (!AbbrEntry)
      return false;
    AbbrOffset = AbbrEntry->Offset;
  }
  if (isTypeUnit()) {
    TypeHash = debug_info.getU64(offset_ptr);
    TypeOffset = debug_info.getU32(offset_ptr);
  } else if (UnitType == DW_UT_split_compile || UnitType == DW_UT_skeleton)
    DWOId = debug_info.getU64(offset_ptr);

  // Header fields all parsed, capture the size of this unit header.
  assert(*offset_ptr - Offset <= 255 && "unexpected header size");
  Size = uint8_t(*offset_ptr - Offset);

  // Type offset is unit-relative; should be after the header and before
  // the end of the current unit.
  bool TypeOffsetOK =
      !isTypeUnit()
          ? true
          : TypeOffset >= Size && TypeOffset < getLength() + SizeOfLength;
  bool LengthOK = debug_info.isValidOffset(getNextUnitOffset() - 1);
  bool VersionOK = DWARFContext::isSupportedVersion(getVersion());
  bool AddrSizeOK = getAddressByteSize() == 4 || getAddressByteSize() == 8;

  if (!LengthOK || !VersionOK || !AddrSizeOK || !TypeOffsetOK)
    return false;

  // Keep track of the highest DWARF version we encounter across all units.
  Context.setMaxVersionIfGreater(getVersion());
  return true;
}

bool DWARFDebugLine::LineTable::parse(DWARFDataExtractor &DebugLineData,
                                      uint32_t *OffsetPtr, const DWARFUnit *U,
                                      raw_ostream *OS) {
  const uint32_t DebugLineOffset = *OffsetPtr;

  clear();

  if (!Prologue.parse(DebugLineData, OffsetPtr, U)) {
    // Restore our offset and return false to indicate failure!
    *OffsetPtr = DebugLineOffset;
    return false;
  }

  if (OS)
    Prologue.dump(*OS);

  const uint32_t EndOffset =
      DebugLineOffset + Prologue.TotalLength + Prologue.sizeofTotalLength();

  // See if we should tell the data extractor the address size.
  if (DebugLineData.getAddressSize() == 0)
    DebugLineData.setAddressSize(Prologue.getAddressSize());
  else
    assert(Prologue.getAddressSize() == 0 ||
           Prologue.getAddressSize() == DebugLineData.getAddressSize());

  ParsingState State(this);

  while (*OffsetPtr < EndOffset) {
    if (OS)
      *OS << format("0x%08.08" PRIx32 ": ", *OffsetPtr);

    uint8_t Opcode = DebugLineData.getU8(OffsetPtr);

    if (OS)
      *OS << format("%02.02" PRIx8 " ", Opcode);

    if (Opcode == 0) {
      // Extended Opcodes always start with a zero opcode followed by
      // a uleb128 length so you can skip ones you don't know about
      uint64_t Len = DebugLineData.getULEB128(OffsetPtr);
      uint32_t ExtOffset = *OffsetPtr;

      // Tolerate zero-length; assume length is correct and soldier on.
      if (Len == 0) {
        if (OS)
          *OS << "Badly formed extended line op (length 0)\n";
        continue;
      }

      uint8_t SubOpcode = DebugLineData.getU8(OffsetPtr);
      if (OS)
        *OS << LNExtendedString(SubOpcode);
      switch (SubOpcode) {
      case DW_LNE_end_sequence:
        // Set the end_sequence register of the state machine to true and
        // append a row to the matrix using the current values of the
        // state-machine registers. Then reset the registers to the initial
        // values specified above. Every statement program sequence must end
        // with a DW_LNE_end_sequence instruction which creates a row whose
        // address is that of the byte after the last target machine instruction
        // of the sequence.
        State.Row.EndSequence = true;
        State.appendRowToMatrix(*OffsetPtr);
        if (OS) {
          *OS << "\n";
          OS->indent(12);
          State.Row.dump(*OS);
        }
        State.resetRowAndSequence();
        break;

      case DW_LNE_set_address:
        // Takes a single relocatable address as an operand. The size of the
        // operand is the size appropriate to hold an address on the target
        // machine. Set the address register to the value given by the
        // relocatable address. All of the other statement program opcodes
        // that affect the address register add a delta to it. This instruction
        // stores a relocatable value into it instead.
        //
        // Make sure the extractor knows the address size.  If not, infer it
        // from the size of the operand.
        if (DebugLineData.getAddressSize() == 0)
          DebugLineData.setAddressSize(Len - 1);
        else
          assert(DebugLineData.getAddressSize() == Len - 1);
        State.Row.Address = DebugLineData.getRelocatedAddress(OffsetPtr);
        if (OS)
          *OS << format(" (0x%16.16" PRIx64 ")", State.Row.Address);
        break;

      case DW_LNE_define_file:
        // Takes 4 arguments. The first is a null terminated string containing
        // a source file name. The second is an unsigned LEB128 number
        // representing the directory index of the directory in which the file
        // was found. The third is an unsigned LEB128 number representing the
        // time of last modification of the file. The fourth is an unsigned
        // LEB128 number representing the length in bytes of the file. The time
        // and length fields may contain LEB128(0) if the information is not
        // available.
//.........这里部分代码省略.........

bool DWARFDebugLine::Prologue::parse(const DWARFDataExtractor &DebugLineData,
                                     uint32_t *OffsetPtr, const DWARFUnit *U) {
  const uint64_t PrologueOffset = *OffsetPtr;

  clear();
  TotalLength = DebugLineData.getU32(OffsetPtr);
  if (TotalLength == UINT32_MAX) {
    FormParams.Format = dwarf::DWARF64;
    TotalLength = DebugLineData.getU64(OffsetPtr);
  } else if (TotalLength >= 0xffffff00) {
    return false;
  }
  FormParams.Version = DebugLineData.getU16(OffsetPtr);
  if (getVersion() < 2)
    return false;

  if (getVersion() >= 5) {
    FormParams.AddrSize = DebugLineData.getU8(OffsetPtr);
    assert((DebugLineData.getAddressSize() == 0 ||
            DebugLineData.getAddressSize() == getAddressSize()) &&
           "Line table header and data extractor disagree");
    SegSelectorSize = DebugLineData.getU8(OffsetPtr);
  }

  PrologueLength = DebugLineData.getUnsigned(OffsetPtr, sizeofPrologueLength());
  const uint64_t EndPrologueOffset = PrologueLength + *OffsetPtr;
  MinInstLength = DebugLineData.getU8(OffsetPtr);
  if (getVersion() >= 4)
    MaxOpsPerInst = DebugLineData.getU8(OffsetPtr);
  DefaultIsStmt = DebugLineData.getU8(OffsetPtr);
  LineBase = DebugLineData.getU8(OffsetPtr);
  LineRange = DebugLineData.getU8(OffsetPtr);
  OpcodeBase = DebugLineData.getU8(OffsetPtr);

  StandardOpcodeLengths.reserve(OpcodeBase - 1);
  for (uint32_t I = 1; I < OpcodeBase; ++I) {
    uint8_t OpLen = DebugLineData.getU8(OffsetPtr);
    StandardOpcodeLengths.push_back(OpLen);
  }

  if (getVersion() >= 5) {
    if (!parseV5DirFileTables(DebugLineData, OffsetPtr, EndPrologueOffset,
                              FormParams, U, HasMD5, IncludeDirectories,
                              FileNames)) {
      fprintf(stderr,
              "warning: parsing line table prologue at 0x%8.8" PRIx64
              " found an invalid directory or file table description at"
              " 0x%8.8" PRIx64 "\n", PrologueOffset, (uint64_t)*OffsetPtr);
      return false;
    }
  } else
    parseV2DirFileTables(DebugLineData, OffsetPtr, EndPrologueOffset,
                         IncludeDirectories, FileNames);

  if (*OffsetPtr != EndPrologueOffset) {
    fprintf(stderr,
            "warning: parsing line table prologue at 0x%8.8" PRIx64
            " should have ended at 0x%8.8" PRIx64
            " but it ended at 0x%8.8" PRIx64 "\n",
            PrologueOffset, EndPrologueOffset, (uint64_t)*OffsetPtr);
    return false;
  }
  return true;
}

static bool
parseV5DirFileTables(const DWARFDataExtractor &DebugLineData,
                     uint32_t *OffsetPtr, uint64_t EndPrologueOffset,
                     const DWARFFormParams &FormParams, const DWARFUnit *U,
                     bool &HasMD5, std::vector<StringRef> &IncludeDirectories,
                     std::vector<DWARFDebugLine::FileNameEntry> &FileNames) {
  // Get the directory entry description.
  ContentDescriptors DirDescriptors =
      parseV5EntryFormat(DebugLineData, OffsetPtr, EndPrologueOffset, nullptr);
  if (DirDescriptors.empty())
    return false;

  // Get the directory entries, according to the format described above.
  int DirEntryCount = DebugLineData.getU8(OffsetPtr);
  for (int I = 0; I != DirEntryCount; ++I) {
    if (*OffsetPtr >= EndPrologueOffset)
      return false;
    for (auto Descriptor : DirDescriptors) {
      DWARFFormValue Value(Descriptor.Form);
      switch (Descriptor.Type) {
      case DW_LNCT_path:
        if (!Value.extractValue(DebugLineData, OffsetPtr, FormParams, U))
          return false;
        IncludeDirectories.push_back(Value.getAsCString().getValue());
        break;
      default:
        if (!Value.skipValue(DebugLineData, OffsetPtr, FormParams))
          return false;
      }
    }
  }

  // Get the file entry description.
  ContentDescriptors FileDescriptors =
      parseV5EntryFormat(DebugLineData, OffsetPtr, EndPrologueOffset, &HasMD5);
  if (FileDescriptors.empty())
    return false;

  // Get the file entries, according to the format described above.
  int FileEntryCount = DebugLineData.getU8(OffsetPtr);
  for (int I = 0; I != FileEntryCount; ++I) {
    if (*OffsetPtr >= EndPrologueOffset)
      return false;
    DWARFDebugLine::FileNameEntry FileEntry;
    for (auto Descriptor : FileDescriptors) {
      DWARFFormValue Value(Descriptor.Form);
      if (!Value.extractValue(DebugLineData, OffsetPtr, FormParams, U))
        return false;
      switch (Descriptor.Type) {
      case DW_LNCT_path:
        FileEntry.Name = Value.getAsCString().getValue();
        break;
      case DW_LNCT_directory_index:
        FileEntry.DirIdx = Value.getAsUnsignedConstant().getValue();
        break;
      case DW_LNCT_timestamp:
        FileEntry.ModTime = Value.getAsUnsignedConstant().getValue();
        break;
      case DW_LNCT_size:
        FileEntry.Length = Value.getAsUnsignedConstant().getValue();
        break;
      case DW_LNCT_MD5:
        assert(Value.getAsBlock().getValue().size() == 16);
        std::uninitialized_copy_n(Value.getAsBlock().getValue().begin(), 16,
                                  FileEntry.Checksum.Bytes.begin());
        break;
      default:
        break;
      }
    }
    FileNames.push_back(FileEntry);
  }
  return true;
}

Error DWARFDebugLine::Prologue::parse(const DWARFDataExtractor &DebugLineData,
                                      uint32_t *OffsetPtr,
                                      const DWARFContext &Ctx,
                                      const DWARFUnit *U) {
  const uint64_t PrologueOffset = *OffsetPtr;

  clear();
  TotalLength = DebugLineData.getU32(OffsetPtr);
  if (TotalLength == UINT32_MAX) {
    FormParams.Format = dwarf::DWARF64;
    TotalLength = DebugLineData.getU64(OffsetPtr);
  } else if (TotalLength >= 0xffffff00) {
    return createStringError(errc::invalid_argument,
        "parsing line table prologue at offset 0x%8.8" PRIx64
        " unsupported reserved unit length found of value 0x%8.8" PRIx64,
        PrologueOffset, TotalLength);
  }
  FormParams.Version = DebugLineData.getU16(OffsetPtr);
  if (getVersion() < 2)
    return createStringError(errc::not_supported,
                       "parsing line table prologue at offset 0x%8.8" PRIx64
                       " found unsupported version 0x%2.2" PRIx16,
                       PrologueOffset, getVersion());

  if (getVersion() >= 5) {
    FormParams.AddrSize = DebugLineData.getU8(OffsetPtr);
    assert((DebugLineData.getAddressSize() == 0 ||
            DebugLineData.getAddressSize() == getAddressSize()) &&
           "Line table header and data extractor disagree");
    SegSelectorSize = DebugLineData.getU8(OffsetPtr);
  }

  PrologueLength = DebugLineData.getUnsigned(OffsetPtr, sizeofPrologueLength());
  const uint64_t EndPrologueOffset = PrologueLength + *OffsetPtr;
  MinInstLength = DebugLineData.getU8(OffsetPtr);
  if (getVersion() >= 4)
    MaxOpsPerInst = DebugLineData.getU8(OffsetPtr);
  DefaultIsStmt = DebugLineData.getU8(OffsetPtr);
  LineBase = DebugLineData.getU8(OffsetPtr);
  LineRange = DebugLineData.getU8(OffsetPtr);
  OpcodeBase = DebugLineData.getU8(OffsetPtr);

  StandardOpcodeLengths.reserve(OpcodeBase - 1);
  for (uint32_t I = 1; I < OpcodeBase; ++I) {
    uint8_t OpLen = DebugLineData.getU8(OffsetPtr);
    StandardOpcodeLengths.push_back(OpLen);
  }

  if (getVersion() >= 5) {
    if (!parseV5DirFileTables(DebugLineData, OffsetPtr, EndPrologueOffset,
                              FormParams, Ctx, U, ContentTypes,
                              IncludeDirectories, FileNames)) {
      return createStringError(errc::invalid_argument,
          "parsing line table prologue at 0x%8.8" PRIx64
          " found an invalid directory or file table description at"
          " 0x%8.8" PRIx64,
          PrologueOffset, (uint64_t)*OffsetPtr);
    }
  } else
    parseV2DirFileTables(DebugLineData, OffsetPtr, EndPrologueOffset,
                         ContentTypes, IncludeDirectories, FileNames);

  if (*OffsetPtr != EndPrologueOffset)
    return createStringError(errc::invalid_argument,
                       "parsing line table prologue at 0x%8.8" PRIx64
                       " should have ended at 0x%8.8" PRIx64
                       " but it ended at 0x%8.8" PRIx64,
                       PrologueOffset, EndPrologueOffset, (uint64_t)*OffsetPtr);
  return Error::success();
}

Error RangeListEntry::extract(DWARFDataExtractor Data, uint32_t End,
                              uint32_t *OffsetPtr) {
  Offset = *OffsetPtr;
  SectionIndex = -1ULL;
  // The caller should guarantee that we have at least 1 byte available, so
  // we just assert instead of revalidate.
  assert(*OffsetPtr < End &&
         "not enough space to extract a rangelist encoding");
  uint8_t Encoding = Data.getU8(OffsetPtr);

  switch (Encoding) {
  case dwarf::DW_RLE_end_of_list:
    Value0 = Value1 = 0;
    break;
  // TODO: Support other encodings.
  case dwarf::DW_RLE_base_addressx:
    return createError("unsupported rnglists encoding DW_RLE_base_addressx "
                       "at offset 0x%" PRIx32,
                       *OffsetPtr - 1);
  case dwarf::DW_RLE_startx_endx:
    return createError("unsupported rnglists encoding DW_RLE_startx_endx at "
                       "offset 0x%" PRIx32,
                       *OffsetPtr - 1);
  case dwarf::DW_RLE_startx_length:
    return createError("unsupported rnglists encoding DW_RLE_startx_length "
                       "at offset 0x%" PRIx32,
                       *OffsetPtr - 1);
  case dwarf::DW_RLE_offset_pair: {
    uint32_t PreviousOffset = *OffsetPtr - 1;
    Value0 = Data.getULEB128(OffsetPtr);
    Value1 = Data.getULEB128(OffsetPtr);
    if (End < *OffsetPtr)
      return createError("read past end of table when reading "
                         "DW_RLE_offset_pair encoding at offset 0x%" PRIx32,
                         PreviousOffset);
    break;
  }
  case dwarf::DW_RLE_base_address: {
    if ((End - *OffsetPtr) < Data.getAddressSize())
      return createError("insufficient space remaining in table for "
                         "DW_RLE_base_address encoding at offset 0x%" PRIx32,
                         *OffsetPtr - 1);
    Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
    break;
  }
  case dwarf::DW_RLE_start_end: {
    if ((End - *OffsetPtr) < unsigned(Data.getAddressSize() * 2))
      return createError("insufficient space remaining in table for "
                         "DW_RLE_start_end encoding "
                         "at offset 0x%" PRIx32,
                         *OffsetPtr - 1);
    Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
    Value1 = Data.getRelocatedAddress(OffsetPtr);
    break;
  }
  case dwarf::DW_RLE_start_length: {
    uint32_t PreviousOffset = *OffsetPtr - 1;
    Value0 = Data.getRelocatedAddress(OffsetPtr, &SectionIndex);
    Value1 = Data.getULEB128(OffsetPtr);
    if (End < *OffsetPtr)
      return createError("read past end of table when reading "
                         "DW_RLE_start_length encoding at offset 0x%" PRIx32,
                         PreviousOffset);
    break;
  }
  default:
    return createError("unknown rnglists encoding 0x%" PRIx32
                       " at offset 0x%" PRIx32,
                       uint32_t(Encoding), *OffsetPtr - 1);
  }

  EntryKind = Encoding;
  return Error::success();
}