C++ DataExtractor::getSLEB128方法代码示例

void FrameEntry::parseInstructions(DataExtractor Data, uint32_t *Offset,
                                   uint32_t EndOffset) {
  while (*Offset < EndOffset) {
    uint8_t Opcode = Data.getU8(Offset);
    // Some instructions have a primary opcode encoded in the top bits.
    uint8_t Primary = Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK;

    if (Primary) {
      // If it's a primary opcode, the first operand is encoded in the bottom
      // bits of the opcode itself.
      uint64_t Op1 = Opcode & DWARF_CFI_PRIMARY_OPERAND_MASK;
      switch (Primary) {
        default: llvm_unreachable("Impossible primary CFI opcode");
        case DW_CFA_advance_loc:
        case DW_CFA_restore:
          addInstruction(Primary, Op1);
          break;
        case DW_CFA_offset:
          addInstruction(Primary, Op1, Data.getULEB128(Offset));
          break;
      }
    } else {
      // Extended opcode - its value is Opcode itself.
      switch (Opcode) {
        default: llvm_unreachable("Invalid extended CFI opcode");
        case DW_CFA_nop:
        case DW_CFA_remember_state:
        case DW_CFA_restore_state:
        case DW_CFA_GNU_window_save:
          // No operands
          addInstruction(Opcode);
          break;
        case DW_CFA_set_loc:
          // Operands: Address
          addInstruction(Opcode, Data.getAddress(Offset));
          break;
        case DW_CFA_advance_loc1:
          // Operands: 1-byte delta
          addInstruction(Opcode, Data.getU8(Offset));
          break;
        case DW_CFA_advance_loc2:
          // Operands: 2-byte delta
          addInstruction(Opcode, Data.getU16(Offset));
          break;
        case DW_CFA_advance_loc4:
          // Operands: 4-byte delta
          addInstruction(Opcode, Data.getU32(Offset));
          break;
        case DW_CFA_restore_extended:
        case DW_CFA_undefined:
        case DW_CFA_same_value:
        case DW_CFA_def_cfa_register:
        case DW_CFA_def_cfa_offset:
          // Operands: ULEB128
          addInstruction(Opcode, Data.getULEB128(Offset));
          break;
        case DW_CFA_def_cfa_offset_sf:
          // Operands: SLEB128
          addInstruction(Opcode, Data.getSLEB128(Offset));
          break;
        case DW_CFA_offset_extended:
        case DW_CFA_register:
        case DW_CFA_def_cfa:
        case DW_CFA_val_offset:
          // Operands: ULEB128, ULEB128
          addInstruction(Opcode, Data.getULEB128(Offset),
                                 Data.getULEB128(Offset));
          break;
        case DW_CFA_offset_extended_sf:
        case DW_CFA_def_cfa_sf:
        case DW_CFA_val_offset_sf:
          // Operands: ULEB128, SLEB128
          addInstruction(Opcode, Data.getULEB128(Offset),
                                 Data.getSLEB128(Offset));
          break;
        case DW_CFA_def_cfa_expression:
        case DW_CFA_expression:
        case DW_CFA_val_expression:
          // TODO: implement this
          report_fatal_error("Values with expressions not implemented yet!");
      }
    }
  }
}

bool DWARFFormValue::extractValue(DataExtractor data, uint32_t *offset_ptr,
                                  const DWARFUnit *cu) {
  bool indirect = false;
  bool is_block = 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 AddrSize =
          (Form == DW_FORM_addr)
              ? cu->getAddressByteSize()
              : getRefAddrSize(cu->getAddressByteSize(), cu->getVersion());
      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr);
      if (AI != cu->getRelocMap()->end()) {
        const std::pair<uint8_t, int64_t> &R = AI->second;
        Value.uval = data.getUnsigned(offset_ptr, AddrSize) + R.second;
      } else
        Value.uval = data.getUnsigned(offset_ptr, AddrSize);
      break;
    }
    case DW_FORM_exprloc:
    case DW_FORM_block:
      Value.uval = data.getULEB128(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_block1:
      Value.uval = data.getU8(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_block2:
      Value.uval = data.getU16(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_block4:
      Value.uval = data.getU32(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_data1:
    case DW_FORM_ref1:
    case DW_FORM_flag:
      Value.uval = data.getU8(offset_ptr);
      break;
    case DW_FORM_data2:
    case DW_FORM_ref2:
      Value.uval = data.getU16(offset_ptr);
      break;
    case DW_FORM_data4:
    case DW_FORM_ref4: {
      RelocAddrMap::const_iterator AI = cu->getRelocMap()->find(*offset_ptr);
      Value.uval = data.getU32(offset_ptr);
      if (AI != cu->getRelocMap()->end())
        Value.uval += AI->second.second;
      break;
    }
    case DW_FORM_data8:
    case DW_FORM_ref8:
      Value.uval = data.getU64(offset_ptr);
      break;
    case DW_FORM_sdata:
      Value.sval = data.getSLEB128(offset_ptr);
      break;
    case DW_FORM_strp: {
      RelocAddrMap::const_iterator AI
        = cu->getRelocMap()->find(*offset_ptr);
      if (AI != cu->getRelocMap()->end()) {
        const std::pair<uint8_t, int64_t> &R = AI->second;
        Value.uval = data.getU32(offset_ptr) + R.second;
      } else
        Value.uval = data.getU32(offset_ptr);
      break;
    }
    case DW_FORM_udata:
    case DW_FORM_ref_udata:
      Value.uval = data.getULEB128(offset_ptr);
      break;
    case DW_FORM_string:
      Value.cstr = data.getCStr(offset_ptr);
      break;
    case DW_FORM_indirect:
      Form = data.getULEB128(offset_ptr);
      indirect = true;
      break;
    case DW_FORM_sec_offset: {
      // FIXME: This is 64-bit for DWARF64.
      RelocAddrMap::const_iterator AI
        = cu->getRelocMap()->find(*offset_ptr);
      if (AI != cu->getRelocMap()->end()) {
        const std::pair<uint8_t, int64_t> &R = AI->second;
        Value.uval = data.getU32(offset_ptr) + R.second;
      } else
        Value.uval = data.getU32(offset_ptr);
      break;
    }
    case DW_FORM_flag_present:
      Value.uval = 1;
      break;
//.........这里部分代码省略.........

void DWARFDebugFrame::parse(DataExtractor Data) {
  uint32_t Offset = 0;
  DenseMap<uint32_t, CIE *> CIEs;

  while (Data.isValidOffset(Offset)) {
    uint32_t StartOffset = Offset;

    bool IsDWARF64 = false;
    uint64_t Length = Data.getU32(&Offset);
    uint64_t Id;

    if (Length == UINT32_MAX) {
      // DWARF-64 is distinguished by the first 32 bits of the initial length
      // field being 0xffffffff. Then, the next 64 bits are the actual entry
      // length.
      IsDWARF64 = true;
      Length = Data.getU64(&Offset);
    }

    // At this point, Offset points to the next field after Length.
    // Length is the structure size excluding itself. Compute an offset one
    // past the end of the structure (needed to know how many instructions to
    // read).
    // TODO: For honest DWARF64 support, DataExtractor will have to treat
    //       offset_ptr as uint64_t*
    uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);

    // The Id field's size depends on the DWARF format
    Id = Data.getUnsigned(&Offset, IsDWARF64 ? 8 : 4);
    bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID);

    if (IsCIE) {
      uint8_t Version = Data.getU8(&Offset);
      const char *Augmentation = Data.getCStr(&Offset);
      uint8_t AddressSize = Version < 4 ? Data.getAddressSize() : Data.getU8(&Offset);
      Data.setAddressSize(AddressSize);
      uint8_t SegmentDescriptorSize = Version < 4 ? 0 : Data.getU8(&Offset);
      uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
      int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
      uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);

      auto Cie = make_unique<CIE>(StartOffset, Length, Version,
                                  StringRef(Augmentation), AddressSize,
                                  SegmentDescriptorSize, CodeAlignmentFactor,
                                  DataAlignmentFactor, ReturnAddressRegister);
      CIEs[StartOffset] = Cie.get();
      Entries.emplace_back(std::move(Cie));
    } else {
      // FDE
      uint64_t CIEPointer = Id;
      uint64_t InitialLocation = Data.getAddress(&Offset);
      uint64_t AddressRange = Data.getAddress(&Offset);

      Entries.emplace_back(new FDE(StartOffset, Length, CIEPointer,
                                   InitialLocation, AddressRange,
                                   CIEs[CIEPointer]));
    }

    Entries.back()->parseInstructions(Data, &Offset, EndStructureOffset);

    if (Offset != EndStructureOffset) {
      std::string Str;
      raw_string_ostream OS(Str);
      OS << format("Parsing entry instructions at %lx failed", StartOffset);
      report_fatal_error(Str);
    }
  }
}

bool DWARFFormValue::skipValue(dwarf::Form Form, DataExtractor DebugInfoData,
                               uint32_t *OffsetPtr,
                               const DWARFFormParams Params) {
  bool Indirect = false;
  do {
    switch (Form) {
    // Blocks of inlined data that have a length field and the data bytes
    // inlined in the .debug_info.
    case DW_FORM_exprloc:
    case DW_FORM_block: {
      uint64_t size = DebugInfoData.getULEB128(OffsetPtr);
      *OffsetPtr += size;
      return true;
    }
    case DW_FORM_block1: {
      uint8_t size = DebugInfoData.getU8(OffsetPtr);
      *OffsetPtr += size;
      return true;
    }
    case DW_FORM_block2: {
      uint16_t size = DebugInfoData.getU16(OffsetPtr);
      *OffsetPtr += size;
      return true;
    }
    case DW_FORM_block4: {
      uint32_t size = DebugInfoData.getU32(OffsetPtr);
      *OffsetPtr += size;
      return true;
    }

    // Inlined NULL terminated C-strings.
    case DW_FORM_string:
      DebugInfoData.getCStr(OffsetPtr);
      return true;

    case DW_FORM_addr:
    case DW_FORM_ref_addr:
    case DW_FORM_flag_present:
    case DW_FORM_data1:
    case DW_FORM_data2:
    case DW_FORM_data4:
    case DW_FORM_data8:
    case DW_FORM_data16:
    case DW_FORM_flag:
    case DW_FORM_ref1:
    case DW_FORM_ref2:
    case DW_FORM_ref4:
    case DW_FORM_ref8:
    case DW_FORM_ref_sig8:
    case DW_FORM_ref_sup4:
    case DW_FORM_ref_sup8:
    case DW_FORM_strx1:
    case DW_FORM_strx2:
    case DW_FORM_strx4:
    case DW_FORM_addrx1:
    case DW_FORM_addrx2:
    case DW_FORM_addrx4:
    case DW_FORM_sec_offset:
    case DW_FORM_strp:
    case DW_FORM_strp_sup:
    case DW_FORM_line_strp:
    case DW_FORM_GNU_ref_alt:
    case DW_FORM_GNU_strp_alt:
      if (Optional<uint8_t> FixedSize =
              DWARFFormValue::getFixedByteSize(Form, Params)) {
        *OffsetPtr += *FixedSize;
        return true;
      }
      return false;

    // signed or unsigned LEB 128 values.
    case DW_FORM_sdata:
      DebugInfoData.getSLEB128(OffsetPtr);
      return true;

    case DW_FORM_udata:
    case DW_FORM_ref_udata:
    case DW_FORM_strx:
    case DW_FORM_addrx:
    case DW_FORM_loclistx:
    case DW_FORM_rnglistx:
    case DW_FORM_GNU_addr_index:
    case DW_FORM_GNU_str_index:
      DebugInfoData.getULEB128(OffsetPtr);
      return true;

    case DW_FORM_indirect:
      Indirect = true;
      Form = static_cast<dwarf::Form>(DebugInfoData.getULEB128(OffsetPtr));
      break;

    default:
      return false;
    }
  } while (Indirect);
  return true;
}

bool
DWARFAbbreviationDeclaration::extract(DataExtractor Data, 
                                      uint32_t* OffsetPtr) {
  clear();
  const uint32_t Offset = *OffsetPtr;
  Code = Data.getULEB128(OffsetPtr);
  if (Code == 0) {
    return false;
  }
  CodeByteSize = *OffsetPtr - Offset;
  Tag = static_cast<llvm::dwarf::Tag>(Data.getULEB128(OffsetPtr));
  if (Tag == DW_TAG_null) {
    clear();
    return false;
  }
  uint8_t ChildrenByte = Data.getU8(OffsetPtr);
  HasChildren = (ChildrenByte == DW_CHILDREN_yes);
  // Assign a value to our optional FixedAttributeSize member variable. If
  // this member variable still has a value after the while loop below, then
  // all attribute data in this abbreviation declaration has a fixed byte size.
  FixedAttributeSize = FixedSizeInfo();

  // Read all of the abbreviation attributes and forms.
  while (true) {
    auto A = static_cast<Attribute>(Data.getULEB128(OffsetPtr));
    auto F = static_cast<Form>(Data.getULEB128(OffsetPtr));
    if (A && F) {
      Optional<int64_t> V;
      bool IsImplicitConst = (F == DW_FORM_implicit_const);
      if (IsImplicitConst) {
        V = Data.getSLEB128(OffsetPtr);
        AttributeSpecs.push_back(AttributeSpec(A, F, V));
        continue;
      }
      // If this abbrevation still has a fixed byte size, then update the
      // FixedAttributeSize as needed.
      switch (F) {
      case DW_FORM_addr:
        if (FixedAttributeSize)
          ++FixedAttributeSize->NumAddrs;
        break;

      case DW_FORM_ref_addr:
        if (FixedAttributeSize)
          ++FixedAttributeSize->NumRefAddrs;
        break;

      case DW_FORM_strp:
      case DW_FORM_GNU_ref_alt:
      case DW_FORM_GNU_strp_alt:
      case DW_FORM_line_strp:
      case DW_FORM_sec_offset:
      case DW_FORM_strp_sup:
        if (FixedAttributeSize)
          ++FixedAttributeSize->NumDwarfOffsets;
        break;

      default:
        // The form has a byte size that doesn't depend on Params.
        // If it's a fixed size, keep track of it.
        if (auto Size =
                DWARFFormValue::getFixedByteSize(F, DWARFFormParams())) {
          V = *Size;
          if (FixedAttributeSize)
            FixedAttributeSize->NumBytes += *V;
          break;
        }
        // Indicate we no longer have a fixed byte size for this
        // abbreviation by clearing the FixedAttributeSize optional value
        // so it doesn't have a value.
        FixedAttributeSize.reset();
        break;
      }
      // Record this attribute and its fixed size if it has one.
      AttributeSpecs.push_back(AttributeSpec(A, F, V));
    } else if (A == 0 && F == 0) {
      // We successfully reached the end of this abbreviation declaration
      // since both attribute and form are zero.
      break;
    } else {
      // Attribute and form pairs must either both be non-zero, in which case
      // they are added to the abbreviation declaration, or both be zero to
      // terminate the abbrevation declaration. In this case only one was
      // zero which is an error.
      clear();
      return false;
    }
  }
  return true;
}

bool
DWARFFormValue::extractValue(DataExtractor data, uint32_t *offset_ptr,
                             const DWARFCompileUnit *cu) {
  bool indirect = false;
  bool is_block = false;
  Value.data = NULL;
  // 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:
      Value.uval = data.getUnsigned(offset_ptr, cu->getAddressByteSize());
      break;
    case DW_FORM_block:
      Value.uval = data.getULEB128(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_block1:
      Value.uval = data.getU8(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_block2:
      Value.uval = data.getU16(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_block4:
      Value.uval = data.getU32(offset_ptr);
      is_block = true;
      break;
    case DW_FORM_data1:
    case DW_FORM_ref1:
    case DW_FORM_flag:
      Value.uval = data.getU8(offset_ptr);
      break;
    case DW_FORM_data2:
    case DW_FORM_ref2:
      Value.uval = data.getU16(offset_ptr);
      break;
    case DW_FORM_data4:
    case DW_FORM_ref4:
      Value.uval = data.getU32(offset_ptr);
      break;
    case DW_FORM_data8:
    case DW_FORM_ref8:
      Value.uval = data.getU64(offset_ptr);
      break;
    case DW_FORM_sdata:
      Value.sval = data.getSLEB128(offset_ptr);
      break;
    case DW_FORM_strp:
      Value.uval = data.getU32(offset_ptr);
      break;
    case DW_FORM_udata:
    case DW_FORM_ref_udata:
      Value.uval = data.getULEB128(offset_ptr);
      break;
    case DW_FORM_string:
      Value.cstr = data.getCStr(offset_ptr);
      // Set the string value to also be the data for inlined cstr form
      // values only so we can tell the differnence between DW_FORM_string
      // and DW_FORM_strp form values
      Value.data = (uint8_t*)Value.cstr;
      break;
    case DW_FORM_indirect:
      Form = data.getULEB128(offset_ptr);
      indirect = true;
      break;
    default:
      return false;
    }
  } while (indirect);

  if (is_block) {
    StringRef str = data.getData().substr(*offset_ptr, Value.uval);
    Value.data = NULL;
    if (!str.empty()) {
      Value.data = reinterpret_cast<const uint8_t *>(str.data());
      *offset_ptr += Value.uval;
    }
  }

  return true;
}

void DWARFDebugFrame::parse(DataExtractor Data) {
  uint32_t Offset = 0;

  while (Data.isValidOffset(Offset)) {
    uint32_t StartOffset = Offset;

    bool IsDWARF64 = false;
    uint64_t Length = Data.getU32(&Offset);
    uint64_t Id;

    if (Length == UINT32_MAX) {
      // DWARF-64 is distinguished by the first 32 bits of the initial length
      // field being 0xffffffff. Then, the next 64 bits are the actual entry
      // length.
      IsDWARF64 = true;
      Length = Data.getU64(&Offset);
    }

    // At this point, Offset points to the next field after Length.
    // Length is the structure size excluding itself. Compute an offset one
    // past the end of the structure (needed to know how many instructions to
    // read).
    // TODO: For honest DWARF64 support, DataExtractor will have to treat
    //       offset_ptr as uint64_t*
    uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);

    // The Id field's size depends on the DWARF format
    Id = Data.getUnsigned(&Offset, IsDWARF64 ? 8 : 4);
    bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) || Id == DW_CIE_ID);

    if (IsCIE) {
      // Note: this is specifically DWARFv3 CIE header structure. It was
      // changed in DWARFv4. We currently don't support reading DWARFv4
      // here because LLVM itself does not emit it (and LLDB doesn't
      // support it either).
      uint8_t Version = Data.getU8(&Offset);
      const char *Augmentation = Data.getCStr(&Offset);
      uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
      int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
      uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);

      Entries.emplace_back(new CIE(StartOffset, Length, Version,
                                   StringRef(Augmentation), CodeAlignmentFactor,
                                   DataAlignmentFactor, ReturnAddressRegister));
    } else {
      // FDE
      uint64_t CIEPointer = Id;
      uint64_t InitialLocation = Data.getAddress(&Offset);
      uint64_t AddressRange = Data.getAddress(&Offset);

      Entries.emplace_back(new FDE(StartOffset, Length, CIEPointer,
                                   InitialLocation, AddressRange));
    }

    Entries.back()->parseInstructions(Data, &Offset, EndStructureOffset);

    if (Offset != EndStructureOffset) {
      string_ostream Str;
      Str << format("Parsing entry instructions at %lx failed", StartOffset);
      report_fatal_error(Str.str());
    }
  }
}

void FrameEntry::parseInstructions(DataExtractor Data, uint32_t *Offset,
                                   uint32_t EndOffset) {
  while (*Offset < EndOffset) {
    uint8_t Opcode = Data.getU8(Offset);
    // Some instructions have a primary opcode encoded in the top bits.
    uint8_t Primary = Opcode & DWARF_CFI_PRIMARY_OPCODE_MASK;

    if (Primary) {
      // If it's a primary opcode, the first operand is encoded in the bottom
      // bits of the opcode itself.
      uint64_t Op1 = Opcode & DWARF_CFI_PRIMARY_OPERAND_MASK;
      switch (Primary) {
        default: llvm_unreachable("Impossible primary CFI opcode");
        case DW_CFA_advance_loc:
        case DW_CFA_restore:
          addInstruction(Primary, Op1);
          break;
        case DW_CFA_offset:
          addInstruction(Primary, Op1, Data.getULEB128(Offset));
          break;
      }
    } else {
      // Extended opcode - its value is Opcode itself.
      switch (Opcode) {
        default: llvm_unreachable("Invalid extended CFI opcode");
        case DW_CFA_nop:
        case DW_CFA_remember_state:
        case DW_CFA_restore_state:
        case DW_CFA_GNU_window_save:
          // No operands
          addInstruction(Opcode);
          break;
        case DW_CFA_set_loc:
          // Operands: Address
          addInstruction(Opcode, Data.getAddress(Offset));
          break;
        case DW_CFA_advance_loc1:
          // Operands: 1-byte delta
          addInstruction(Opcode, Data.getU8(Offset));
          break;
        case DW_CFA_advance_loc2:
          // Operands: 2-byte delta
          addInstruction(Opcode, Data.getU16(Offset));
          break;
        case DW_CFA_advance_loc4:
          // Operands: 4-byte delta
          addInstruction(Opcode, Data.getU32(Offset));
          break;
        case DW_CFA_restore_extended:
        case DW_CFA_undefined:
        case DW_CFA_same_value:
        case DW_CFA_def_cfa_register:
        case DW_CFA_def_cfa_offset:
        case DW_CFA_GNU_args_size:
          // Operands: ULEB128
          addInstruction(Opcode, Data.getULEB128(Offset));
          break;
        case DW_CFA_def_cfa_offset_sf:
          // Operands: SLEB128
          addInstruction(Opcode, Data.getSLEB128(Offset));
          break;
        case DW_CFA_offset_extended:
        case DW_CFA_register:
        case DW_CFA_def_cfa:
        case DW_CFA_val_offset: {
          // Operands: ULEB128, ULEB128
          // Note: We can not embed getULEB128 directly into function
          // argument list. getULEB128 changes Offset and order of evaluation
          // for arguments is unspecified.
          auto op1 = Data.getULEB128(Offset);
          auto op2 = Data.getULEB128(Offset);
          addInstruction(Opcode, op1, op2);
          break;
        }
        case DW_CFA_offset_extended_sf:
        case DW_CFA_def_cfa_sf:
        case DW_CFA_val_offset_sf: {
          // Operands: ULEB128, SLEB128
          // Note: see comment for the previous case
          auto op1 = Data.getULEB128(Offset);
          auto op2 = (uint64_t)Data.getSLEB128(Offset);
          addInstruction(Opcode, op1, op2);
          break;
        }
        case DW_CFA_def_cfa_expression:
          // FIXME: Parse the actual instruction.
          *Offset += Data.getULEB128(Offset);
          break;
        case DW_CFA_expression:
        case DW_CFA_val_expression: {
          // FIXME: Parse the actual instruction.
          Data.getULEB128(Offset);
          *Offset += Data.getULEB128(Offset);
          break;
        }
      }
    }
  }
}

//.........这里部分代码省略.........
          fileEntry.ModTime = debug_line_data.getULEB128(offset_ptr);
          fileEntry.Length = debug_line_data.getULEB128(offset_ptr);
          prologue->FileNames.push_back(fileEntry);
        }
        break;

      default:
        // Length doesn't include the zero opcode byte or the length itself, but
        // it does include the sub_opcode, so we have to adjust for that below
        (*offset_ptr) += arg_size;
        break;
      }
    } else if (opcode < prologue->OpcodeBase) {
      switch (opcode) {
      // Standard Opcodes
      case DW_LNS_copy:
        // Takes no arguments. Append a row to the matrix using the
        // current values of the state-machine registers. Then set
        // the basic_block register to false.
        state.appendRowToMatrix(*offset_ptr);
        break;

      case DW_LNS_advance_pc:
        // Takes a single unsigned LEB128 operand, multiplies it by the
        // min_inst_length field of the prologue, and adds the
        // result to the address register of the state machine.
        state.Address += debug_line_data.getULEB128(offset_ptr) *
                         prologue->MinInstLength;
        break;

      case DW_LNS_advance_line:
        // Takes a single signed LEB128 operand and adds that value to
        // the line register of the state machine.
        state.Line += debug_line_data.getSLEB128(offset_ptr);
        break;

      case DW_LNS_set_file:
        // Takes a single unsigned LEB128 operand and stores it in the file
        // register of the state machine.
        state.File = debug_line_data.getULEB128(offset_ptr);
        break;

      case DW_LNS_set_column:
        // Takes a single unsigned LEB128 operand and stores it in the
        // column register of the state machine.
        state.Column = debug_line_data.getULEB128(offset_ptr);
        break;

      case DW_LNS_negate_stmt:
        // Takes no arguments. Set the is_stmt register of the state
        // machine to the logical negation of its current value.
        state.IsStmt = !state.IsStmt;
        break;

      case DW_LNS_set_basic_block:
        // Takes no arguments. Set the basic_block register of the
        // state machine to true
        state.BasicBlock = true;
        break;

      case DW_LNS_const_add_pc:
        // Takes no arguments. Add to the address register of the state
        // machine the address increment value corresponding to special
        // opcode 255. The motivation for DW_LNS_const_add_pc is this:
        // when the statement program needs to advance the address by a
        // small amount, it can use a single special opcode, which occupies

void DWARFDebugFrame::parse(DataExtractor Data) {
  uint32_t Offset = 0;
  DenseMap<uint32_t, CIE *> CIEs;

  while (Data.isValidOffset(Offset)) {
    uint32_t StartOffset = Offset;

    auto ReportError = [StartOffset](const char *ErrorMsg) {
      std::string Str;
      raw_string_ostream OS(Str);
      OS << format(ErrorMsg, StartOffset);
      OS.flush();
      report_fatal_error(Str);
    };

    bool IsDWARF64 = false;
    uint64_t Length = Data.getU32(&Offset);
    uint64_t Id;

    if (Length == UINT32_MAX) {
      // DWARF-64 is distinguished by the first 32 bits of the initial length
      // field being 0xffffffff. Then, the next 64 bits are the actual entry
      // length.
      IsDWARF64 = true;
      Length = Data.getU64(&Offset);
    }

    // At this point, Offset points to the next field after Length.
    // Length is the structure size excluding itself. Compute an offset one
    // past the end of the structure (needed to know how many instructions to
    // read).
    // TODO: For honest DWARF64 support, DataExtractor will have to treat
    //       offset_ptr as uint64_t*
    uint32_t StartStructureOffset = Offset;
    uint32_t EndStructureOffset = Offset + static_cast<uint32_t>(Length);

    // The Id field's size depends on the DWARF format
    Id = Data.getUnsigned(&Offset, (IsDWARF64 && !IsEH) ? 8 : 4);
    bool IsCIE = ((IsDWARF64 && Id == DW64_CIE_ID) ||
                  Id == DW_CIE_ID ||
                  (IsEH && !Id));

    if (IsCIE) {
      uint8_t Version = Data.getU8(&Offset);
      const char *Augmentation = Data.getCStr(&Offset);
      StringRef AugmentationString(Augmentation ? Augmentation : "");
      uint8_t AddressSize = Version < 4 ? Data.getAddressSize() :
                                          Data.getU8(&Offset);
      Data.setAddressSize(AddressSize);
      uint8_t SegmentDescriptorSize = Version < 4 ? 0 : Data.getU8(&Offset);
      uint64_t CodeAlignmentFactor = Data.getULEB128(&Offset);
      int64_t DataAlignmentFactor = Data.getSLEB128(&Offset);
      uint64_t ReturnAddressRegister = Data.getULEB128(&Offset);

      // Parse the augmentation data for EH CIEs
      StringRef AugmentationData("");
      uint32_t FDEPointerEncoding = DW_EH_PE_omit;
      uint32_t LSDAPointerEncoding = DW_EH_PE_omit;
      if (IsEH) {
        Optional<uint32_t> PersonalityEncoding;
        Optional<uint64_t> Personality;

        Optional<uint64_t> AugmentationLength;
        uint32_t StartAugmentationOffset;
        uint32_t EndAugmentationOffset;

        // Walk the augmentation string to get all the augmentation data.
        for (unsigned i = 0, e = AugmentationString.size(); i != e; ++i) {
          switch (AugmentationString[i]) {
            default:
              ReportError("Unknown augmentation character in entry at %lx");
            case 'L':
              LSDAPointerEncoding = Data.getU8(&Offset);
              break;
            case 'P': {
              if (Personality)
                ReportError("Duplicate personality in entry at %lx");
              PersonalityEncoding = Data.getU8(&Offset);
              Personality = readPointer(Data, Offset, *PersonalityEncoding);
              break;
            }
            case 'R':
              FDEPointerEncoding = Data.getU8(&Offset);
              break;
            case 'z':
              if (i)
                ReportError("'z' must be the first character at %lx");
              // Parse the augmentation length first.  We only parse it if
              // the string contains a 'z'.
              AugmentationLength = Data.getULEB128(&Offset);
              StartAugmentationOffset = Offset;
              EndAugmentationOffset = Offset +
                static_cast<uint32_t>(*AugmentationLength);
          }
        }

        if (AugmentationLength.hasValue()) {
          if (Offset != EndAugmentationOffset)
            ReportError("Parsing augmentation data at %lx failed");

//.........这里部分代码省略.........

//.........这里部分代码省略.........
        break;

      case DW_LNE_set_discriminator:
        State.Row.Discriminator = debug_line_data.getULEB128(offset_ptr);
        break;

      default:
        // Length doesn't include the zero opcode byte or the length itself, but
        // it does include the sub_opcode, so we have to adjust for that below
        (*offset_ptr) += arg_size;
        break;
      }
    } else if (opcode < Prologue.OpcodeBase) {
      switch (opcode) {
      // Standard Opcodes
      case DW_LNS_copy:
        // Takes no arguments. Append a row to the matrix using the
        // current values of the state-machine registers. Then set
        // the basic_block register to false.
        State.appendRowToMatrix(*offset_ptr);
        break;

      case DW_LNS_advance_pc:
        // Takes a single unsigned LEB128 operand, multiplies it by the
        // min_inst_length field of the prologue, and adds the
        // result to the address register of the state machine.
        State.Row.Address +=
            debug_line_data.getULEB128(offset_ptr) * Prologue.MinInstLength;
        break;

      case DW_LNS_advance_line:
        // Takes a single signed LEB128 operand and adds that value to
        // the line register of the state machine.
        State.Row.Line += debug_line_data.getSLEB128(offset_ptr);
        break;

      case DW_LNS_set_file:
        // Takes a single unsigned LEB128 operand and stores it in the file
        // register of the state machine.
        State.Row.File = debug_line_data.getULEB128(offset_ptr);
        break;

      case DW_LNS_set_column:
        // Takes a single unsigned LEB128 operand and stores it in the
        // column register of the state machine.
        State.Row.Column = debug_line_data.getULEB128(offset_ptr);
        break;

      case DW_LNS_negate_stmt:
        // Takes no arguments. Set the is_stmt register of the state
        // machine to the logical negation of its current value.
        State.Row.IsStmt = !State.Row.IsStmt;
        break;

      case DW_LNS_set_basic_block:
        // Takes no arguments. Set the basic_block register of the
        // state machine to true
        State.Row.BasicBlock = true;
        break;

      case DW_LNS_const_add_pc:
        // Takes no arguments. Add to the address register of the state
        // machine the address increment value corresponding to special
        // opcode 255. The motivation for DW_LNS_const_add_pc is this:
        // when the statement program needs to advance the address by a
        // small amount, it can use a single special opcode, which occupies