C++ ObjectImage类代码示例

// compute stub buffer size for the given section
unsigned RuntimeDyldImpl::computeSectionStubBufSize(ObjectImage &Obj,
                                                    const SectionRef &Section) {
  unsigned StubSize = getMaxStubSize();
  if (StubSize == 0) {
    return 0;
  }
  // FIXME: this is an inefficient way to handle this. We should computed the
  // necessary section allocation size in loadObject by walking all the sections
  // once.
  unsigned StubBufSize = 0;
  for (section_iterator SI = Obj.begin_sections(), SE = Obj.end_sections();
       SI != SE; ++SI) {
    section_iterator RelSecI = SI->getRelocatedSection();
    if (!(RelSecI == Section))
      continue;

    for (const RelocationRef &Reloc : SI->relocations()) {
      (void)Reloc;
      StubBufSize += StubSize;
    }
  }

  // Get section data size and alignment
  uint64_t DataSize = Section.getSize();
  uint64_t Alignment64 = Section.getAlignment();

  // Add stubbuf size alignment
  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
  unsigned StubAlignment = getStubAlignment();
  unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
  if (StubAlignment > EndAlignment)
    StubBufSize += StubAlignment - EndAlignment;
  return StubBufSize;
}

void RuntimeDyldMachO::finalizeLoad(ObjectImage &ObjImg,
                                    ObjSectionToIDMap &SectionMap) {
  unsigned EHFrameSID = RTDYLD_INVALID_SECTION_ID;
  unsigned TextSID = RTDYLD_INVALID_SECTION_ID;
  unsigned ExceptTabSID = RTDYLD_INVALID_SECTION_ID;
  ObjSectionToIDMap::iterator i, e;
  for (i = SectionMap.begin(), e = SectionMap.end(); i != e; ++i) {
    const SectionRef &Section = i->first;
    StringRef Name;
    Section.getName(Name);
    if (Name == "__eh_frame")
      EHFrameSID = i->second;
    else if (Name == "__text")
      TextSID = i->second;
    else if (Name == "__gcc_except_tab")
      ExceptTabSID = i->second;
    else if (Name == "__jump_table")
      populateJumpTable(cast<MachOObjectFile>(*ObjImg.getObjectFile()),
                        Section, i->second);
    else if (Name == "__pointers")
      populatePointersSection(cast<MachOObjectFile>(*ObjImg.getObjectFile()),
                              Section, i->second);
  }
  UnregisteredEHFrameSections.push_back(
      EHFrameRelatedSections(EHFrameSID, TextSID, ExceptTabSID));
}

void RuntimeDyldImpl::emitCommonSymbols(ObjectImage &Obj,
                                        const CommonSymbolMap &CommonSymbols,
                                        uint64_t TotalSize,
                                        SymbolTableMap &SymbolTable) {
  // Allocate memory for the section
  unsigned SectionID = Sections.size();
  uint8_t *Addr = MemMgr->allocateDataSection(TotalSize, sizeof(void*),
                                              SectionID);
  if (!Addr)
    report_fatal_error("Unable to allocate memory for common symbols!");
  uint64_t Offset = 0;
  Sections.push_back(SectionEntry(Addr, TotalSize, TotalSize, 0));
  memset(Addr, 0, TotalSize);

  DEBUG(dbgs() << "emitCommonSection SectionID: " << SectionID
               << " new addr: " << format("%p", Addr)
               << " DataSize: " << TotalSize
               << "\n");

  // Assign the address of each symbol
  for (CommonSymbolMap::const_iterator it = CommonSymbols.begin(),
       itEnd = CommonSymbols.end(); it != itEnd; it++) {
    StringRef Name;
    it->first.getName(Name);
    Obj.updateSymbolAddress(it->first, (uint64_t)Addr);
    SymbolTable[Name.data()] = SymbolLoc(SectionID, Offset);
    uint64_t Size = it->second;
    Offset += Size;
    Addr += Size;
  }
}

void MCJIT::generateCodeForModule(Module *M) {
  // Get a thread lock to make sure we aren't trying to load multiple times
  MutexGuard locked(lock);

  // This must be a module which has already been added to this MCJIT instance.
  assert(OwnedModules.ownsModule(M) &&
         "MCJIT::generateCodeForModule: Unknown module.");

  // Re-compilation is not supported
  if (OwnedModules.hasModuleBeenLoaded(M))
    return;

  std::unique_ptr<ObjectBuffer> ObjectToLoad;
  // Try to load the pre-compiled object from cache if possible
  if (ObjCache) {
    std::unique_ptr<MemoryBuffer> PreCompiledObject(ObjCache->getObject(M));
    if (PreCompiledObject.get())
      ObjectToLoad.reset(new ObjectBuffer(PreCompiledObject.release()));
  }

  // If the cache did not contain a suitable object, compile the object
  if (!ObjectToLoad) {
    ObjectToLoad.reset(emitObject(M));
    assert(ObjectToLoad.get() && "Compilation did not produce an object.");
  }

  // Load the object into the dynamic linker.
  // MCJIT now owns the ObjectImage pointer (via its LoadedObjects list).
  ObjectImage *LoadedObject = Dyld.loadObject(ObjectToLoad.release());
  LoadedObjects.push_back(LoadedObject);
  if (!LoadedObject)
    report_fatal_error(Dyld.getErrorString());

  // FIXME: Make this optional, maybe even move it to a JIT event listener
  LoadedObject->registerWithDebugger();

  NotifyObjectEmitted(*LoadedObject);

  OwnedModules.markModuleAsLoaded(M);
}

    virtual void NotifyObjectEmitted(const ObjectImage &obj)
    {
        uint64_t Addr;
        object::SymbolRef::Type SymbolType;

        #ifdef LLVM35
        for (const object::SymbolRef &sym_iter : obj.symbols()) {
            sym_iter.getType(SymbolType);
            if (SymbolType != object::SymbolRef::ST_Function) continue;
            sym_iter.getAddress(Addr);
            ObjectInfo tmp = {obj.getObjectFile(), sym_iter, obj.getData().size()};
            objectmap[Addr] = tmp;
        }
        #else
        error_code itererr; 
        object::symbol_iterator sym_iter = obj.begin_symbols();
        object::symbol_iterator sym_end = obj.end_symbols();
        for (; sym_iter != sym_end; sym_iter.increment(itererr)) {
            sym_iter->getType(SymbolType);
            if (SymbolType != object::SymbolRef::ST_Function) continue;
            sym_iter->getAddress(Addr);

            ObjectInfo tmp = {obj.getObjectFile(), *sym_iter};
            objectmap[Addr] = tmp;
        }
        #endif
    }

void RuntimeDyldMachO::makeValueAddendPCRel(RelocationValueRef &Value,
                                            ObjectImage &ObjImg,
                                            const relocation_iterator &RI,
                                            unsigned OffsetToNextPC) {
  const MachOObjectFile &Obj =
      static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
  MachO::any_relocation_info RelInfo =
      Obj.getRelocation(RI->getRawDataRefImpl());

  bool IsPCRel = Obj.getAnyRelocationPCRel(RelInfo);
  if (IsPCRel) {
    uint64_t RelocAddr = 0;
    RI->getAddress(RelocAddr);
    Value.Addend += RelocAddr + OffsetToNextPC;
  }
}

RelocationValueRef RuntimeDyldMachO::getRelocationValueRef(
    ObjectImage &ObjImg, const relocation_iterator &RI,
    const RelocationEntry &RE, ObjSectionToIDMap &ObjSectionToID,
    const SymbolTableMap &Symbols) {

  const MachOObjectFile &Obj =
      static_cast<const MachOObjectFile &>(*ObjImg.getObjectFile());
  MachO::any_relocation_info RelInfo =
      Obj.getRelocation(RI->getRawDataRefImpl());
  RelocationValueRef Value;

  bool IsExternal = Obj.getPlainRelocationExternal(RelInfo);
  if (IsExternal) {
    symbol_iterator Symbol = RI->getSymbol();
    StringRef TargetName;
    Symbol->getName(TargetName);
    SymbolTableMap::const_iterator SI = Symbols.find(TargetName.data());
    if (SI != Symbols.end()) {
      Value.SectionID = SI->second.first;
      Value.Addend = SI->second.second + RE.Addend;
    } else {
      SI = GlobalSymbolTable.find(TargetName.data());
      if (SI != GlobalSymbolTable.end()) {
        Value.SectionID = SI->second.first;
        Value.Addend = SI->second.second + RE.Addend;
      } else {
        Value.SymbolName = TargetName.data();
        Value.Addend = RE.Addend;
      }
    }
  } else {
    SectionRef Sec = Obj.getRelocationSection(RelInfo);
    bool IsCode = false;
    Sec.isText(IsCode);
    Value.SectionID = findOrEmitSection(ObjImg, Sec, IsCode, ObjSectionToID);
    uint64_t Addr;
    Sec.getAddress(Addr);
    Value.Addend = RE.Addend - Addr;
  }

  return Value;
}

void RuntimeDyldMachO::processRelocationRef(unsigned SectionID,
                                            RelocationRef RelI,
                                            ObjectImage &Obj,
                                            ObjSectionToIDMap &ObjSectionToID,
                                            const SymbolTableMap &Symbols,
                                            StubMap &Stubs) {
  const ObjectFile *OF = Obj.getObjectFile();
  const MachOObjectFile *MachO = static_cast<const MachOObjectFile*>(OF);
  MachO::any_relocation_info RE= MachO->getRelocation(RelI.getRawDataRefImpl());

  uint32_t RelType = MachO->getAnyRelocationType(RE);

  // FIXME: Properly handle scattered relocations.
  //        For now, optimistically skip these: they can often be ignored, as
  //        the static linker will already have applied the relocation, and it
  //        only needs to be reapplied if symbols move relative to one another.
  //        Note: This will fail horribly where the relocations *do* need to be
  //        applied, but that was already the case.
  if (MachO->isRelocationScattered(RE))
    return;

  RelocationValueRef Value;
  SectionEntry &Section = Sections[SectionID];

  bool isExtern = MachO->getPlainRelocationExternal(RE);
  bool IsPCRel = MachO->getAnyRelocationPCRel(RE);
  unsigned Size = MachO->getAnyRelocationLength(RE);
  uint64_t Offset;
  RelI.getOffset(Offset);
  uint8_t *LocalAddress = Section.Address + Offset;
  unsigned NumBytes = 1 << Size;
  uint64_t Addend = 0;
  memcpy(&Addend, LocalAddress, NumBytes);

  if (isExtern) {
    // Obtain the symbol name which is referenced in the relocation
    symbol_iterator Symbol = RelI.getSymbol();
    StringRef TargetName;
    Symbol->getName(TargetName);
    // First search for the symbol in the local symbol table
    SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
    if (lsi != Symbols.end()) {
      Value.SectionID = lsi->second.first;
      Value.Addend = lsi->second.second + Addend;
    } else {
      // Search for the symbol in the global symbol table
      SymbolTableMap::const_iterator gsi = GlobalSymbolTable.find(TargetName.data());
      if (gsi != GlobalSymbolTable.end()) {
        Value.SectionID = gsi->second.first;
        Value.Addend = gsi->second.second + Addend;
      } else {
        Value.SymbolName = TargetName.data();
        Value.Addend = Addend;
      }
    }
  } else {
    SectionRef Sec = MachO->getRelocationSection(RE);
    bool IsCode = false;
    Sec.isText(IsCode);
    Value.SectionID = findOrEmitSection(Obj, Sec, IsCode, ObjSectionToID);
    uint64_t Addr;
    Sec.getAddress(Addr);
    Value.Addend = Addend - Addr;
    if (IsPCRel)
      Value.Addend += Offset + NumBytes;
  }

  if (Arch == Triple::x86_64 && (RelType == MachO::X86_64_RELOC_GOT ||
                                 RelType == MachO::X86_64_RELOC_GOT_LOAD)) {
    assert(IsPCRel);
    assert(Size == 2);
    StubMap::const_iterator i = Stubs.find(Value);
    uint8_t *Addr;
    if (i != Stubs.end()) {
      Addr = Section.Address + i->second;
    } else {
      Stubs[Value] = Section.StubOffset;
      uint8_t *GOTEntry = Section.Address + Section.StubOffset;
      RelocationEntry RE(SectionID, Section.StubOffset,
                         MachO::X86_64_RELOC_UNSIGNED, 0, false, 3);
      if (Value.SymbolName)
        addRelocationForSymbol(RE, Value.SymbolName);
      else
        addRelocationForSection(RE, Value.SectionID);
      Section.StubOffset += 8;
      Addr = GOTEntry;
    }
    resolveRelocation(Section, Offset, (uint64_t)Addr,
                      MachO::X86_64_RELOC_UNSIGNED, Value.Addend, true, 2);
  } else if (Arch == Triple::arm &&
             (RelType & 0xf) == MachO::ARM_RELOC_BR24) {
    // This is an ARM branch relocation, need to use a stub function.

    //  Look up for existing stub.
    StubMap::const_iterator i = Stubs.find(Value);
    if (i != Stubs.end())
      resolveRelocation(Section, Offset,
                        (uint64_t)Section.Address + i->second,
                        RelType, 0, IsPCRel, Size);
    else {
//.........这里部分代码省略.........

void RuntimeDyldMachO::processRelocationRef(const ObjRelocationInfo &Rel,
                                            ObjectImage &Obj,
                                            ObjSectionToIDMap &ObjSectionToID,
                                            const SymbolTableMap &Symbols,
                                            StubMap &Stubs) {

  uint32_t RelType = (uint32_t) (Rel.Type & 0xffffffffL);
  RelocationValueRef Value;
  SectionEntry &Section = Sections[Rel.SectionID];

  bool isExtern = (RelType >> 27) & 1;
  if (isExtern) {
    // Obtain the symbol name which is referenced in the relocation
    StringRef TargetName;
    const SymbolRef &Symbol = Rel.Symbol;
    Symbol.getName(TargetName);
    // First search for the symbol in the local symbol table
    SymbolTableMap::const_iterator lsi = Symbols.find(TargetName.data());
    if (lsi != Symbols.end()) {
      Value.SectionID = lsi->second.first;
      Value.Addend = lsi->second.second;
    } else {
      // Search for the symbol in the global symbol table
      SymbolTableMap::const_iterator gsi = GlobalSymbolTable.find(TargetName.data());
      if (gsi != GlobalSymbolTable.end()) {
        Value.SectionID = gsi->second.first;
        Value.Addend = gsi->second.second;
      } else
        Value.SymbolName = TargetName.data();
    }
  } else {
    error_code err;
    uint8_t sectionIndex = static_cast<uint8_t>(RelType & 0xFF);
    section_iterator si = Obj.begin_sections(),
                     se = Obj.end_sections();
    for (uint8_t i = 1; i < sectionIndex; i++) {
      error_code err;
      si.increment(err);
      if (si == se)
        break;
    }
    assert(si != se && "No section containing relocation!");
    Value.SectionID = findOrEmitSection(Obj, *si, true, ObjSectionToID);
    Value.Addend = 0;
    // FIXME: The size and type of the relocation determines if we can
    // encode an Addend in the target location itself, and if so, how many
    // bytes we should read in order to get it. We don't yet support doing
    // that, and just assuming it's sizeof(intptr_t) is blatantly wrong.
    //Value.Addend = *(const intptr_t *)Target;
    if (Value.Addend) {
      // The MachO addend is an offset from the current section.  We need it
      // to be an offset from the destination section
      Value.Addend += Section.ObjAddress - Sections[Value.SectionID].ObjAddress;
    }
  }

  if (Arch == Triple::arm && (RelType & 0xf) == macho::RIT_ARM_Branch24Bit) {
    // This is an ARM branch relocation, need to use a stub function.

    //  Look up for existing stub.
    StubMap::const_iterator i = Stubs.find(Value);
    if (i != Stubs.end())
      resolveRelocation(Section, Rel.Offset,
                        (uint64_t)Section.Address + i->second,
                        RelType, 0);
    else {
      // Create a new stub function.
      Stubs[Value] = Section.StubOffset;
      uint8_t *StubTargetAddr = createStubFunction(Section.Address +
                                                   Section.StubOffset);
      RelocationEntry RE(Rel.SectionID, StubTargetAddr - Section.Address,
                         macho::RIT_Vanilla, Value.Addend);
      if (Value.SymbolName)
        addRelocationForSymbol(RE, Value.SymbolName);
      else
        addRelocationForSection(RE, Value.SectionID);
      resolveRelocation(Section, Rel.Offset,
                        (uint64_t)Section.Address + Section.StubOffset,
                        RelType, 0);
      Section.StubOffset += getMaxStubSize();
    }
  } else {
    RelocationEntry RE(Rel.SectionID, Rel.Offset, RelType, Value.Addend);
    if (Value.SymbolName)
      addRelocationForSymbol(RE, Value.SymbolName);
    else
      addRelocationForSection(RE, Value.SectionID);
  }
}

    virtual void NotifyObjectEmitted(const ObjectImage &obj)
#endif
    {
        int8_t gc_state = jl_gc_safe_enter();
        uv_rwlock_wrlock(&threadsafe);
        jl_gc_safe_leave(gc_state);
#ifdef LLVM36
        object::section_iterator Section = obj.section_begin();
        object::section_iterator EndSection = obj.section_end();
#else
        object::section_iterator Section = obj.begin_sections();
        object::section_iterator EndSection = obj.end_sections();
#endif

#if defined(_OS_WINDOWS_)
        uint64_t SectionAddrCheck = 0; // assert that all of the Sections are at the same location
        uint8_t *UnwindData = NULL;
#if defined(_CPU_X86_64_)
        uint8_t *catchjmp = NULL;
        for (const object::SymbolRef &sym_iter : obj.symbols()) {
            StringRef sName;
#ifdef LLVM37
            sName = sym_iter.getName().get();
#else
            sym_iter.getName(sName);
#endif
            uint8_t **pAddr = NULL;
            if (sName.equals("__UnwindData")) {
                pAddr = &UnwindData;
            }
            else if (sName.equals("__catchjmp")) {
                pAddr = &catchjmp;
            }
            if (pAddr) {
                uint64_t Addr, SectionAddr;
#if defined(LLVM38)
                Addr = sym_iter.getAddress().get();
                Section = sym_iter.getSection().get();
                assert(Section != EndSection && Section->isText());
                SectionAddr = L.getSectionLoadAddress(*Section);
#elif defined(LLVM37)
                Addr = sym_iter.getAddress().get();
                sym_iter.getSection(Section);
                assert(Section != EndSection && Section->isText());
                Section->getName(sName);
                SectionAddr = L.getSectionLoadAddress(sName);
#elif defined(LLVM36)
                sym_iter.getAddress(Addr);
                sym_iter.getSection(Section);
                assert(Section != EndSection && Section->isText());
                Section->getName(sName);
                SectionAddr = L.getSectionLoadAddress(sName);
#else // LLVM35
                sym_iter.getAddress(Addr);
                sym_iter.getSection(Section);
                assert(Section != EndSection);
                assert(!Section->isText(isText) && isText);
                Section->getAddress(SectionAddr);
#endif
#ifdef LLVM36
                Addr += SectionAddr;
#endif
                *pAddr = (uint8_t*)Addr;
                if (SectionAddrCheck)
                    assert(SectionAddrCheck == SectionAddr);
                else
                    SectionAddrCheck = SectionAddr;
            }
        }
        assert(catchjmp);
        assert(UnwindData);
        assert(SectionAddrCheck);
        catchjmp[0] = 0x48;
        catchjmp[1] = 0xb8; // mov RAX, QWORD PTR [&_seh_exception_handle]
        *(uint64_t*)(&catchjmp[2]) = (uint64_t)&_seh_exception_handler;
        catchjmp[10] = 0xff;
        catchjmp[11] = 0xe0; // jmp RAX
        UnwindData[0] = 0x09; // version info, UNW_FLAG_EHANDLER
        UnwindData[1] = 4;    // size of prolog (bytes)
        UnwindData[2] = 2;    // count of unwind codes (slots)
        UnwindData[3] = 0x05; // frame register (rbp) = rsp
        UnwindData[4] = 4;    // second instruction
        UnwindData[5] = 0x03; // mov RBP, RSP
        UnwindData[6] = 1;    // first instruction
        UnwindData[7] = 0x50; // push RBP
        *(DWORD*)&UnwindData[8] = (DWORD)(catchjmp - (uint8_t*)SectionAddrCheck); // relative location of catchjmp
#endif // defined(_OS_X86_64_)
#endif // defined(_OS_WINDOWS_)

#ifdef LLVM37
        auto symbols = object::computeSymbolSizes(obj);
        for(const auto &sym_size : symbols) {
            const object::SymbolRef &sym_iter = sym_size.first;
            object::SymbolRef::Type SymbolType = sym_iter.getType();
            if (SymbolType != object::SymbolRef::ST_Function) continue;
            uint64_t Size = sym_size.second;
            uint64_t Addr = sym_iter.getAddress().get();
#ifdef LLVM38
            Section = sym_iter.getSection().get();
#else
//.........这里部分代码省略.........

// Compute an upper bound of the memory size that is required to load all
// sections
void RuntimeDyldImpl::computeTotalAllocSize(ObjectImage &Obj,
                                            uint64_t &CodeSize,
                                            uint64_t &DataSizeRO,
                                            uint64_t &DataSizeRW) {
  // Compute the size of all sections required for execution
  std::vector<uint64_t> CodeSectionSizes;
  std::vector<uint64_t> ROSectionSizes;
  std::vector<uint64_t> RWSectionSizes;
  uint64_t MaxAlignment = sizeof(void *);

  // Collect sizes of all sections to be loaded;
  // also determine the max alignment of all sections
  for (section_iterator SI = Obj.begin_sections(), SE = Obj.end_sections();
       SI != SE; ++SI) {
    const SectionRef &Section = *SI;

    bool IsRequired = Section.isRequiredForExecution();

    // Consider only the sections that are required to be loaded for execution
    if (IsRequired) {
      StringRef Name;
      uint64_t DataSize = Section.getSize();
      uint64_t Alignment64 = Section.getAlignment();
      bool IsCode = Section.isText();
      bool IsReadOnly = Section.isReadOnlyData();
      Check(Section.getName(Name));
      unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;

      uint64_t StubBufSize = computeSectionStubBufSize(Obj, Section);
      uint64_t SectionSize = DataSize + StubBufSize;

      // The .eh_frame section (at least on Linux) needs an extra four bytes
      // padded
      // with zeroes added at the end.  For MachO objects, this section has a
      // slightly different name, so this won't have any effect for MachO
      // objects.
      if (Name == ".eh_frame")
        SectionSize += 4;

      if (SectionSize > 0) {
        // save the total size of the section
        if (IsCode) {
          CodeSectionSizes.push_back(SectionSize);
        } else if (IsReadOnly) {
          ROSectionSizes.push_back(SectionSize);
        } else {
          RWSectionSizes.push_back(SectionSize);
        }
        // update the max alignment
        if (Alignment > MaxAlignment) {
          MaxAlignment = Alignment;
        }
      }
    }
  }

  // Compute the size of all common symbols
  uint64_t CommonSize = 0;
  for (symbol_iterator I = Obj.begin_symbols(), E = Obj.end_symbols(); I != E;
       ++I) {
    uint32_t Flags = I->getFlags();
    if (Flags & SymbolRef::SF_Common) {
      // Add the common symbols to a list.  We'll allocate them all below.
      uint64_t Size = 0;
      Check(I->getSize(Size));
      CommonSize += Size;
    }
  }
  if (CommonSize != 0) {
    RWSectionSizes.push_back(CommonSize);
  }

  // Compute the required allocation space for each different type of sections
  // (code, read-only data, read-write data) assuming that all sections are
  // allocated with the max alignment. Note that we cannot compute with the
  // individual alignments of the sections, because then the required size
  // depends on the order, in which the sections are allocated.
  CodeSize = computeAllocationSizeForSections(CodeSectionSizes, MaxAlignment);
  DataSizeRO = computeAllocationSizeForSections(ROSectionSizes, MaxAlignment);
  DataSizeRW = computeAllocationSizeForSections(RWSectionSizes, MaxAlignment);
}

unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
                                      const SectionRef &Section,
                                      bool IsCode) {

  unsigned StubBufSize = 0,
           StubSize = getMaxStubSize();
  error_code err;
  if (StubSize > 0) {
    for (relocation_iterator i = Section.begin_relocations(),
         e = Section.end_relocations(); i != e; i.increment(err), Check(err))
      StubBufSize += StubSize;
  }
  StringRef data;
  uint64_t Alignment64;
  Check(Section.getContents(data));
  Check(Section.getAlignment(Alignment64));

  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
  bool IsRequired;
  bool IsVirtual;
  bool IsZeroInit;
  uint64_t DataSize;
  Check(Section.isRequiredForExecution(IsRequired));
  Check(Section.isVirtual(IsVirtual));
  Check(Section.isZeroInit(IsZeroInit));
  Check(Section.getSize(DataSize));

  unsigned Allocate;
  unsigned SectionID = Sections.size();
  uint8_t *Addr;
  const char *pData = 0;

  // Some sections, such as debug info, don't need to be loaded for execution.
  // Leave those where they are.
  if (IsRequired) {
    Allocate = DataSize + StubBufSize;
    Addr = IsCode
      ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
      : MemMgr->allocateDataSection(Allocate, Alignment, SectionID);
    if (!Addr)
      report_fatal_error("Unable to allocate section memory!");

    // Virtual sections have no data in the object image, so leave pData = 0
    if (!IsVirtual)
      pData = data.data();

    // Zero-initialize or copy the data from the image
    if (IsZeroInit || IsVirtual)
      memset(Addr, 0, DataSize);
    else
      memcpy(Addr, pData, DataSize);

    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " obj addr: " << format("%p", pData)
                 << " new addr: " << format("%p", Addr)
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
    Obj.updateSectionAddress(Section, (uint64_t)Addr);
  }
  else {
    // Even if we didn't load the section, we need to record an entry for it
    // to handle later processing (and by 'handle' I mean don't do anything
    // with these sections).
    Allocate = 0;
    Addr = 0;
    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " obj addr: " << format("%p", data.data())
                 << " new addr: 0"
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
  }

  Sections.push_back(SectionEntry(Addr, Allocate, DataSize,(uintptr_t)pData));
  return SectionID;
}

    virtual void NotifyObjectEmitted(const ObjectImage &obj)
#endif
    {
        uint64_t Addr;
        uint64_t Size;
        object::SymbolRef::Type SymbolType;
#ifdef LLVM36
        object::section_iterator Section = obj.section_begin();
        object::section_iterator EndSection = obj.section_end();
        uint64_t SectionAddr = 0;
        StringRef sName;
#else
        object::section_iterator Section = obj.begin_sections();
        object::section_iterator EndSection = obj.end_sections();
        bool isText;
#ifndef _OS_LINUX_
        StringRef sName;
#endif
#endif

#ifndef LLVM36
        uint64_t SectionAddr = 0;
#endif
        uint64_t SectionSize = 0;
        uint64_t SectionAddrCheck = 0; // assert that all of the Sections are at the same location

#if defined(_OS_WINDOWS_)
#if defined(_CPU_X86_64_)
        uint8_t *UnwindData = NULL;
        uint8_t *catchjmp = NULL;
        for (const object::SymbolRef &sym_iter : obj.symbols()) {
#  ifdef LLVM37
            sName = sym_iter.getName().get();
#  else
            sym_iter.getName(sName);
#  endif
            if (sName.equals("__UnwindData")) {
#  ifdef LLVM37
                Addr = sym_iter.getAddress().get();
#  else
                sym_iter.getAddress(Addr);
#  endif
                sym_iter.getSection(Section);
#  ifdef LLVM36
                assert(Section->isText());
                Section->getName(sName);
                SectionAddr = L.getSectionLoadAddress(sName);
                Addr += SectionAddr;
#  else
                if (Section->isText(isText) || !isText) assert(0 && "!isText");
                Section->getAddress(SectionAddr);
#  endif
                UnwindData = (uint8_t*)Addr;
                if (SectionAddrCheck)
                    assert(SectionAddrCheck == SectionAddr);
                else
                    SectionAddrCheck = SectionAddr;
            }
            if (sName.equals("__catchjmp")) {
#  ifdef LLVM37
                Addr = sym_iter.getAddress().get();
#  else
                sym_iter.getAddress(Addr);
#  endif
                sym_iter.getSection(Section);
#  ifdef LLVM36
                assert(Section->isText());
                Section->getName(sName);
                SectionAddr = L.getSectionLoadAddress(sName);
                Addr += SectionAddr;
#  else
                if (Section->isText(isText) || !isText) assert(0 && "!isText");
                Section->getAddress(SectionAddr);
#  endif
                catchjmp = (uint8_t*)Addr;
                if (SectionAddrCheck)
                    assert(SectionAddrCheck == SectionAddr);
                else
                    SectionAddrCheck = SectionAddr;
            }
        }
        assert(catchjmp);
        assert(UnwindData);
        catchjmp[0] = 0x48;
        catchjmp[1] = 0xb8; // mov RAX, QWORD PTR [&_seh_exception_handle]
        *(uint64_t*)(&catchjmp[2]) = (uint64_t)&_seh_exception_handler;
        catchjmp[10] = 0xff;
        catchjmp[11] = 0xe0; // jmp RAX
        UnwindData[0] = 0x09; // version info, UNW_FLAG_EHANDLER
        UnwindData[1] = 4;    // size of prolog (bytes)
        UnwindData[2] = 2;    // count of unwind codes (slots)
        UnwindData[3] = 0x05; // frame register (rbp) = rsp
        UnwindData[4] = 4;    // second instruction
        UnwindData[5] = 0x03; // mov RBP, RSP
        UnwindData[6] = 1;    // first instruction
        UnwindData[7] = 0x50; // push RBP
        *(DWORD*)&UnwindData[8] = (DWORD)(catchjmp - (uint8_t*)SectionAddr); // relative location of catchjmp
#else // defined(_OS_X86_64_)
        uint8_t *UnwindData = NULL;
#endif // defined(_OS_X86_64_)
//.........这里部分代码省略.........

unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
                                      const SectionRef &Section,
                                      bool IsCode) {

  unsigned StubBufSize = 0,
           StubSize = getMaxStubSize();
  error_code err;
  const ObjectFile *ObjFile = Obj.getObjectFile();
  // FIXME: this is an inefficient way to handle this. We should computed the
  // necessary section allocation size in loadObject by walking all the sections
  // once.
  if (StubSize > 0) {
    for (section_iterator SI = ObjFile->begin_sections(),
           SE = ObjFile->end_sections();
         SI != SE; SI.increment(err), Check(err)) {
      section_iterator RelSecI = SI->getRelocatedSection();
      if (!(RelSecI == Section))
        continue;

      for (relocation_iterator I = SI->begin_relocations(),
             E = SI->end_relocations(); I != E; I.increment(err), Check(err)) {
        StubBufSize += StubSize;
      }
    }
  }

  StringRef data;
  uint64_t Alignment64;
  Check(Section.getContents(data));
  Check(Section.getAlignment(Alignment64));

  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
  bool IsRequired;
  bool IsVirtual;
  bool IsZeroInit;
  bool IsReadOnly;
  uint64_t DataSize;
  StringRef Name;
  Check(Section.isRequiredForExecution(IsRequired));
  Check(Section.isVirtual(IsVirtual));
  Check(Section.isZeroInit(IsZeroInit));
  Check(Section.isReadOnlyData(IsReadOnly));
  Check(Section.getSize(DataSize));
  Check(Section.getName(Name));
  if (StubSize > 0) {
    unsigned StubAlignment = getStubAlignment();
    unsigned EndAlignment = (DataSize | Alignment) & -(DataSize | Alignment);
    if (StubAlignment > EndAlignment)
      StubBufSize += StubAlignment - EndAlignment;
  }

  unsigned Allocate;
  unsigned SectionID = Sections.size();
  uint8_t *Addr;
  const char *pData = 0;

  // Some sections, such as debug info, don't need to be loaded for execution.
  // Leave those where they are.
  if (IsRequired) {
    Allocate = DataSize + StubBufSize;
    Addr = IsCode
      ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID)
      : MemMgr->allocateDataSection(Allocate, Alignment, SectionID, IsReadOnly);
    if (!Addr)
      report_fatal_error("Unable to allocate section memory!");

    // Virtual sections have no data in the object image, so leave pData = 0
    if (!IsVirtual)
      pData = data.data();

    // Zero-initialize or copy the data from the image
    if (IsZeroInit || IsVirtual)
      memset(Addr, 0, DataSize);
    else
      memcpy(Addr, pData, DataSize);

    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " Name: " << Name
                 << " obj addr: " << format("%p", pData)
                 << " new addr: " << format("%p", Addr)
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
    Obj.updateSectionAddress(Section, (uint64_t)Addr);
  }
  else {
    // Even if we didn't load the section, we need to record an entry for it
    // to handle later processing (and by 'handle' I mean don't do anything
    // with these sections).
    Allocate = 0;
    Addr = 0;
    DEBUG(dbgs() << "emitSection SectionID: " << SectionID
                 << " Name: " << Name
                 << " obj addr: " << format("%p", data.data())
                 << " new addr: 0"
                 << " DataSize: " << DataSize
                 << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate
                 << "\n");
//.........这里部分代码省略.........

unsigned RuntimeDyldImpl::emitSection(ObjectImage &Obj,
                                      const SectionRef &Section, bool IsCode) {

  StringRef data;
  uint64_t Alignment64;
  Check(Section.getContents(data));
  Check(Section.getAlignment(Alignment64));

  unsigned Alignment = (unsigned)Alignment64 & 0xffffffffL;
  bool IsRequired;
  bool IsVirtual;
  bool IsZeroInit;
  bool IsReadOnly;
  uint64_t DataSize;
  unsigned PaddingSize = 0;
  unsigned StubBufSize = 0;
  StringRef Name;
  Check(Section.isRequiredForExecution(IsRequired));
  Check(Section.isVirtual(IsVirtual));
  Check(Section.isZeroInit(IsZeroInit));
  Check(Section.isReadOnlyData(IsReadOnly));
  Check(Section.getSize(DataSize));
  Check(Section.getName(Name));

  StubBufSize = computeSectionStubBufSize(Obj, Section);

  // The .eh_frame section (at least on Linux) needs an extra four bytes padded
  // with zeroes added at the end.  For MachO objects, this section has a
  // slightly different name, so this won't have any effect for MachO objects.
  if (Name == ".eh_frame")
    PaddingSize = 4;

  uintptr_t Allocate;
  unsigned SectionID = Sections.size();
  uint8_t *Addr;
  const char *pData = 0;

  // Some sections, such as debug info, don't need to be loaded for execution.
  // Leave those where they are.
  if (IsRequired) {
    Allocate = DataSize + PaddingSize + StubBufSize;
    Addr = IsCode ? MemMgr->allocateCodeSection(Allocate, Alignment, SectionID,
                                                Name)
                  : MemMgr->allocateDataSection(Allocate, Alignment, SectionID,
                                                Name, IsReadOnly);
    if (!Addr)
      report_fatal_error("Unable to allocate section memory!");

    // Virtual sections have no data in the object image, so leave pData = 0
    if (!IsVirtual)
      pData = data.data();

    // Zero-initialize or copy the data from the image
    if (IsZeroInit || IsVirtual)
      memset(Addr, 0, DataSize);
    else
      memcpy(Addr, pData, DataSize);

    // Fill in any extra bytes we allocated for padding
    if (PaddingSize != 0) {
      memset(Addr + DataSize, 0, PaddingSize);
      // Update the DataSize variable so that the stub offset is set correctly.
      DataSize += PaddingSize;
    }

    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
                 << " obj addr: " << format("%p", pData)
                 << " new addr: " << format("%p", Addr)
                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate << "\n");
    Obj.updateSectionAddress(Section, (uint64_t)Addr);
  } else {
    // Even if we didn't load the section, we need to record an entry for it
    // to handle later processing (and by 'handle' I mean don't do anything
    // with these sections).
    Allocate = 0;
    Addr = 0;
    DEBUG(dbgs() << "emitSection SectionID: " << SectionID << " Name: " << Name
                 << " obj addr: " << format("%p", data.data()) << " new addr: 0"
                 << " DataSize: " << DataSize << " StubBufSize: " << StubBufSize
                 << " Allocate: " << Allocate << "\n");
  }

  Sections.push_back(SectionEntry(Name, Addr, DataSize, (uintptr_t)pData));
  return SectionID;
}