C++ GlobalVariable::copyAttributesFrom方法代码示例

GlobalVariable* cloneGlobalVariableDecl(Module &Dst, const GlobalVariable &GV,
                                        ValueToValueMapTy *VMap) {
  GlobalVariable *NewGV = new GlobalVariable(
      Dst, GV.getValueType(), GV.isConstant(),
      GV.getLinkage(), nullptr, GV.getName(), nullptr,
      GV.getThreadLocalMode(), GV.getType()->getAddressSpace());
  NewGV->copyAttributesFrom(&GV);
  if (VMap)
    (*VMap)[&GV] = NewGV;
  return NewGV;
}

 virtual Value * materializeValueFor(Value * V) {
     if(Function * fn = dyn_cast<Function>(V)) {
         assert(fn->getParent() == src);
         Function * newfn = dest->getFunction(fn->getName());
         if(!newfn) {
             newfn = Function::Create(fn->getFunctionType(),fn->getLinkage(), fn->getName(),dest);
             newfn->copyAttributesFrom(fn);
         }
         if(!fn->isDeclaration() && newfn->isDeclaration() && copyGlobal(fn,data)) {
             for(Function::arg_iterator II = newfn->arg_begin(), I = fn->arg_begin(), E = fn->arg_end(); I != E; ++I, ++II) {
                 II->setName(I->getName());
                 VMap[I] = II;
             }
             VMap[fn] = newfn;
             SmallVector<ReturnInst*,8> Returns;
             CloneFunctionInto(newfn, fn, VMap, true, Returns, "", NULL, NULL, this);
         }
         return newfn;
     } else if(GlobalVariable * GV = dyn_cast<GlobalVariable>(V)) {
         GlobalVariable * newGV = dest->getGlobalVariable(GV->getName(),true);
         if(!newGV) {
             newGV = new GlobalVariable(*dest,GV->getType()->getElementType(),GV->isConstant(),GV->getLinkage(),NULL,GV->getName(),NULL,GlobalVariable::NotThreadLocal,GV->getType()->getAddressSpace());
             newGV->copyAttributesFrom(GV);
             if(!GV->isDeclaration()) {
                 if(!copyGlobal(GV,data)) {
                     newGV->setExternallyInitialized(true);
                 } else if(GV->hasInitializer()) {
                     Value * C = MapValue(GV->getInitializer(),VMap,RF_None,NULL,this);
                     newGV->setInitializer(cast<Constant>(C));
                 }
             }
         }
         return newGV;
     } else if(MDNode * MD = dyn_cast<MDNode>(V)) {
         DISubprogram SP(MD);
         if(DI != NULL && SP.isSubprogram()) {
             
             if(Function * OF = SP.getFunction()) {
                 Function * F = cast<Function>(MapValue(OF,VMap,RF_None,NULL,this));
                 DISubprogram NSP = DI->createFunction(SP.getContext(), SP.getName(), SP.getLinkageName(),
                                                   DI->createFile(SP.getFilename(),SP.getDirectory()),
                                                   SP.getLineNumber(), SP.getType(),
                                                   SP.isLocalToUnit(), SP.isDefinition(),
                                                   SP.getScopeLineNumber(),SP.getFlags(),SP.isOptimized(),
                                                   F);
                 return NSP;
             }
             /* fallthrough */
         }
         /* fallthrough */
     }
     return NULL;
 }

GlobalVariable* cloneGlobalVariableDecl(Module &Dst, const GlobalVariable &GV,
                                        ValueToValueMapTy *VMap) {
  assert(GV.getParent() != &Dst && "Can't copy decl over existing global var.");
  GlobalVariable *NewGV = new GlobalVariable(
      Dst, GV.getType()->getElementType(), GV.isConstant(),
      GV.getLinkage(), nullptr, GV.getName(), nullptr,
      GV.getThreadLocalMode(), GV.getType()->getAddressSpace());
  NewGV->copyAttributesFrom(&GV);
  if (VMap)
    (*VMap)[&GV] = NewGV;
  return NewGV;
}

// Connect Modules via prototypes, each owned by module `M`
static GlobalVariable *global_proto(GlobalVariable *G, Module *M = NULL)
{
    // Copy the GlobalVariable, but without the initializer, so it becomes a declaration
    GlobalVariable *proto = new GlobalVariable(G->getType()->getElementType(),
            G->isConstant(), GlobalVariable::ExternalLinkage,
            NULL, G->getName(),  G->getThreadLocalMode());
    proto->copyAttributesFrom(G);
#ifdef LLVM35
    // DLLImport only needs to be set for the shadow module
    // it just gets annoying in the JIT
    proto->setDLLStorageClass(GlobalValue::DefaultStorageClass);
#endif
    if (M)
        M->getGlobalList().push_back(proto);
    return proto;
}

std::unique_ptr<Module> llvm::CloneModule(
    const Module *M, ValueToValueMapTy &VMap,
    std::function<bool(const GlobalValue *)> ShouldCloneDefinition) {
  // First off, we need to create the new module.
  std::unique_ptr<Module> New =
      llvm::make_unique<Module>(M->getModuleIdentifier(), M->getContext());
  New->setDataLayout(M->getDataLayout());
  New->setTargetTriple(M->getTargetTriple());
  New->setModuleInlineAsm(M->getModuleInlineAsm());
   
  // Loop over all of the global variables, making corresponding globals in the
  // new module.  Here we add them to the VMap and to the new Module.  We
  // don't worry about attributes or initializers, they will come later.
  //
  for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
       I != E; ++I) {
    GlobalVariable *GV = new GlobalVariable(*New, 
                                            I->getValueType(),
                                            I->isConstant(), I->getLinkage(),
                                            (Constant*) nullptr, I->getName(),
                                            (GlobalVariable*) nullptr,
                                            I->getThreadLocalMode(),
                                            I->getType()->getAddressSpace());
    GV->copyAttributesFrom(&*I);
    VMap[&*I] = GV;
  }

  // Loop over the functions in the module, making external functions as before
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    Function *NF =
        Function::Create(cast<FunctionType>(I->getValueType()),
                         I->getLinkage(), I->getName(), New.get());
    NF->copyAttributesFrom(&*I);
    VMap[&*I] = NF;
  }

  // Loop over the aliases in the module
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I) {
    if (!ShouldCloneDefinition(&*I)) {
      // An alias cannot act as an external reference, so we need to create
      // either a function or a global variable depending on the value type.
      // FIXME: Once pointee types are gone we can probably pick one or the
      // other.
      GlobalValue *GV;
      if (I->getValueType()->isFunctionTy())
        GV = Function::Create(cast<FunctionType>(I->getValueType()),
                              GlobalValue::ExternalLinkage, I->getName(),
                              New.get());
      else
        GV = new GlobalVariable(
            *New, I->getValueType(), false, GlobalValue::ExternalLinkage,
            (Constant *)nullptr, I->getName(), (GlobalVariable *)nullptr,
            I->getThreadLocalMode(), I->getType()->getAddressSpace());
      VMap[&*I] = GV;
      // We do not copy attributes (mainly because copying between different
      // kinds of globals is forbidden), but this is generally not required for
      // correctness.
      continue;
    }
    auto *GA = GlobalAlias::create(I->getValueType(),
                                   I->getType()->getPointerAddressSpace(),
                                   I->getLinkage(), I->getName(), New.get());
    GA->copyAttributesFrom(&*I);
    VMap[&*I] = GA;
  }
  
  // Now that all of the things that global variable initializer can refer to
  // have been created, loop through and copy the global variable referrers
  // over...  We also set the attributes on the global now.
  //
  for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
       I != E; ++I) {
    GlobalVariable *GV = cast<GlobalVariable>(VMap[&*I]);
    if (!ShouldCloneDefinition(&*I)) {
      // Skip after setting the correct linkage for an external reference.
      GV->setLinkage(GlobalValue::ExternalLinkage);
      continue;
    }
    if (I->hasInitializer())
      GV->setInitializer(MapValue(I->getInitializer(), VMap));
  }

  // Similarly, copy over function bodies now...
  //
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    Function *F = cast<Function>(VMap[&*I]);
    if (!ShouldCloneDefinition(&*I)) {
      // Skip after setting the correct linkage for an external reference.
      F->setLinkage(GlobalValue::ExternalLinkage);
      // Personality function is not valid on a declaration.
      F->setPersonalityFn(nullptr);
      continue;
    }
    if (!I->isDeclaration()) {
      Function::arg_iterator DestI = F->arg_begin();
      for (Function::const_arg_iterator J = I->arg_begin(); J != I->arg_end();
           ++J) {
        DestI->setName(J->getName());
        VMap[&*J] = &*DestI++;
//.........这里部分代码省略.........

Module *llvm::CloneModule(const Module *M, ValueToValueMapTy &VMap) {
  // First off, we need to create the new module.
  Module *New = new Module(M->getModuleIdentifier(), M->getContext());
  New->setDataLayout(M->getDataLayout());
  New->setTargetTriple(M->getTargetTriple());
  New->setModuleInlineAsm(M->getModuleInlineAsm());
   
  // Loop over all of the global variables, making corresponding globals in the
  // new module.  Here we add them to the VMap and to the new Module.  We
  // don't worry about attributes or initializers, they will come later.
  //
  for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
       I != E; ++I) {
    GlobalVariable *GV = new GlobalVariable(*New, 
                                            I->getType()->getElementType(),
                                            I->isConstant(), I->getLinkage(),
                                            (Constant*) nullptr, I->getName(),
                                            (GlobalVariable*) nullptr,
                                            I->getThreadLocalMode(),
                                            I->getType()->getAddressSpace());
    GV->copyAttributesFrom(I);
    VMap[I] = GV;
  }

  // Loop over the functions in the module, making external functions as before
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    Function *NF =
      Function::Create(cast<FunctionType>(I->getType()->getElementType()),
                       I->getLinkage(), I->getName(), New);
    NF->copyAttributesFrom(I);
    VMap[I] = NF;
  }

  // Loop over the aliases in the module
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I) {
    auto *PTy = cast<PointerType>(I->getType());
    auto *GA =
        GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
                            I->getLinkage(), I->getName(), New);
    GA->copyAttributesFrom(I);
    VMap[I] = GA;
  }
  
  // Now that all of the things that global variable initializer can refer to
  // have been created, loop through and copy the global variable referrers
  // over...  We also set the attributes on the global now.
  //
  for (Module::const_global_iterator I = M->global_begin(), E = M->global_end();
       I != E; ++I) {
    GlobalVariable *GV = cast<GlobalVariable>(VMap[I]);
    if (I->hasInitializer())
      GV->setInitializer(MapValue(I->getInitializer(), VMap));
  }

  // Similarly, copy over function bodies now...
  //
  for (Module::const_iterator I = M->begin(), E = M->end(); I != E; ++I) {
    Function *F = cast<Function>(VMap[I]);
    if (!I->isDeclaration()) {
      Function::arg_iterator DestI = F->arg_begin();
      for (Function::const_arg_iterator J = I->arg_begin(); J != I->arg_end();
           ++J) {
        DestI->setName(J->getName());
        VMap[J] = DestI++;
      }

      SmallVector<ReturnInst*, 8> Returns;  // Ignore returns cloned.
      CloneFunctionInto(F, I, VMap, /*ModuleLevelChanges=*/true, Returns);
    }
  }

  // And aliases
  for (Module::const_alias_iterator I = M->alias_begin(), E = M->alias_end();
       I != E; ++I) {
    GlobalAlias *GA = cast<GlobalAlias>(VMap[I]);
    if (const Constant *C = I->getAliasee())
      GA->setAliasee(cast<GlobalObject>(MapValue(C, VMap)));
  }

  // And named metadata....
  for (Module::const_named_metadata_iterator I = M->named_metadata_begin(),
         E = M->named_metadata_end(); I != E; ++I) {
    const NamedMDNode &NMD = *I;
    NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName());
    for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i)
      NewNMD->addOperand(MapValue(NMD.getOperand(i), VMap));
  }

  return New;
}

bool GenericToNVVM::runOnModule(Module &M) {
  // Create a clone of each global variable that has the default address space.
  // The clone is created with the global address space  specifier, and the pair
  // of original global variable and its clone is placed in the GVMap for later
  // use.

  for (Module::global_iterator I = M.global_begin(), E = M.global_end();
       I != E;) {
    GlobalVariable *GV = &*I++;
    if (GV->getType()->getAddressSpace() == llvm::ADDRESS_SPACE_GENERIC &&
        !llvm::isTexture(*GV) && !llvm::isSurface(*GV) &&
        !llvm::isSampler(*GV) && !GV->getName().startswith("llvm.")) {
      GlobalVariable *NewGV = new GlobalVariable(
          M, GV->getValueType(), GV->isConstant(),
          GV->getLinkage(),
          GV->hasInitializer() ? GV->getInitializer() : nullptr,
          "", GV, GV->getThreadLocalMode(), llvm::ADDRESS_SPACE_GLOBAL);
      NewGV->copyAttributesFrom(GV);
      GVMap[GV] = NewGV;
    }
  }

  // Return immediately, if every global variable has a specific address space
  // specifier.
  if (GVMap.empty()) {
    return false;
  }

  // Walk through the instructions in function defitinions, and replace any use
  // of original global variables in GVMap with a use of the corresponding
  // copies in GVMap.  If necessary, promote constants to instructions.
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) {
    if (I->isDeclaration()) {
      continue;
    }
    IRBuilder<> Builder(I->getEntryBlock().getFirstNonPHIOrDbg());
    for (Function::iterator BBI = I->begin(), BBE = I->end(); BBI != BBE;
         ++BBI) {
      for (BasicBlock::iterator II = BBI->begin(), IE = BBI->end(); II != IE;
           ++II) {
        for (unsigned i = 0, e = II->getNumOperands(); i < e; ++i) {
          Value *Operand = II->getOperand(i);
          if (isa<Constant>(Operand)) {
            II->setOperand(
                i, remapConstant(&M, &*I, cast<Constant>(Operand), Builder));
          }
        }
      }
    }
    ConstantToValueMap.clear();
  }

  // Copy GVMap over to a standard value map.
  ValueToValueMapTy VM;
  for (auto I = GVMap.begin(), E = GVMap.end(); I != E; ++I)
    VM[I->first] = I->second;

  // Walk through the metadata section and update the debug information
  // associated with the global variables in the default address space.
  for (NamedMDNode &I : M.named_metadata()) {
    remapNamedMDNode(VM, &I);
  }

  // Walk through the global variable  initializers, and replace any use of
  // original global variables in GVMap with a use of the corresponding copies
  // in GVMap.  The copies need to be bitcast to the original global variable
  // types, as we cannot use cvta in global variable initializers.
  for (GVMapTy::iterator I = GVMap.begin(), E = GVMap.end(); I != E;) {
    GlobalVariable *GV = I->first;
    GlobalVariable *NewGV = I->second;

    // Remove GV from the map so that it can be RAUWed.  Note that
    // DenseMap::erase() won't invalidate any iterators but this one.
    auto Next = std::next(I);
    GVMap.erase(I);
    I = Next;

    Constant *BitCastNewGV = ConstantExpr::getPointerCast(NewGV, GV->getType());
    // At this point, the remaining uses of GV should be found only in global
    // variable initializers, as other uses have been already been removed
    // while walking through the instructions in function definitions.
    GV->replaceAllUsesWith(BitCastNewGV);
    std::string Name = GV->getName();
    GV->eraseFromParent();
    NewGV->setName(Name);
  }
  assert(GVMap.empty() && "Expected it to be empty by now");

  return true;
}

// This function replaces all global variables with new variables that have
// trailing redzones. It also creates a function that poisons
// redzones and inserts this function into llvm.global_ctors.
bool AddressSanitizer::insertGlobalRedzones(Module &M) {
  SmallVector<GlobalVariable *, 16> GlobalsToChange;

  for (Module::GlobalListType::iterator G = M.global_begin(),
       E = M.global_end(); G != E; ++G) {
    if (ShouldInstrumentGlobal(G))
      GlobalsToChange.push_back(G);
  }

  size_t n = GlobalsToChange.size();
  if (n == 0) return false;

  // A global is described by a structure
  //   size_t beg;
  //   size_t size;
  //   size_t size_with_redzone;
  //   const char *name;
  //   size_t has_dynamic_init;
  // We initialize an array of such structures and pass it to a run-time call.
  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
                                               IntptrTy, IntptrTy,
                                               IntptrTy, NULL);
  SmallVector<Constant *, 16> Initializers(n), DynamicInit;

  IRBuilder<> IRB(CtorInsertBefore);

  if (ClInitializers)
    FindDynamicInitializers(M);

  // The addresses of the first and last dynamically initialized globals in
  // this TU.  Used in initialization order checking.
  Value *FirstDynamic = 0, *LastDynamic = 0;

  for (size_t i = 0; i < n; i++) {
    GlobalVariable *G = GlobalsToChange[i];
    PointerType *PtrTy = cast<PointerType>(G->getType());
    Type *Ty = PtrTy->getElementType();
    uint64_t SizeInBytes = TD->getTypeAllocSize(Ty);
    uint64_t RightRedzoneSize = RedzoneSize +
        (RedzoneSize - (SizeInBytes % RedzoneSize));
    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
    // Determine whether this global should be poisoned in initialization.
    bool GlobalHasDynamicInitializer = HasDynamicInitializer(G);
    // Don't check initialization order if this global is blacklisted.
    GlobalHasDynamicInitializer &= !BL->isInInit(*G);

    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
    Constant *NewInitializer = ConstantStruct::get(
        NewTy, G->getInitializer(),
        Constant::getNullValue(RightRedZoneTy), NULL);

    SmallString<2048> DescriptionOfGlobal = G->getName();
    DescriptionOfGlobal += " (";
    DescriptionOfGlobal += M.getModuleIdentifier();
    DescriptionOfGlobal += ")";
    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);

    // Create a new global variable with enough space for a redzone.
    GlobalVariable *NewGlobal = new GlobalVariable(
        M, NewTy, G->isConstant(), G->getLinkage(),
        NewInitializer, "", G, G->getThreadLocalMode());
    NewGlobal->copyAttributesFrom(G);
    NewGlobal->setAlignment(RedzoneSize);

    Value *Indices2[2];
    Indices2[0] = IRB.getInt32(0);
    Indices2[1] = IRB.getInt32(0);

    G->replaceAllUsesWith(
        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
    NewGlobal->takeName(G);
    G->eraseFromParent();

    Initializers[i] = ConstantStruct::get(
        GlobalStructTy,
        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
        ConstantInt::get(IntptrTy, SizeInBytes),
        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
        ConstantExpr::getPointerCast(Name, IntptrTy),
        ConstantInt::get(IntptrTy, GlobalHasDynamicInitializer),
        NULL);

    // Populate the first and last globals declared in this TU.
    if (ClInitializers && GlobalHasDynamicInitializer) {
      LastDynamic = ConstantExpr::getPointerCast(NewGlobal, IntptrTy);
      if (FirstDynamic == 0)
        FirstDynamic = LastDynamic;
    }

    DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
  }

  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
  GlobalVariable *AllGlobals = new GlobalVariable(
      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");

//.........这里部分代码省略.........

/// If there were any appending global variables, link them together now.
Expected<Constant *>
IRLinker::linkAppendingVarProto(GlobalVariable *DstGV,
                                const GlobalVariable *SrcGV) {
  Type *EltTy = cast<ArrayType>(TypeMap.get(SrcGV->getValueType()))
                    ->getElementType();

  // FIXME: This upgrade is done during linking to support the C API.  Once the
  // old form is deprecated, we should move this upgrade to
  // llvm::UpgradeGlobalVariable() and simplify the logic here and in
  // Mapper::mapAppendingVariable() in ValueMapper.cpp.
  StringRef Name = SrcGV->getName();
  bool IsNewStructor = false;
  bool IsOldStructor = false;
  if (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") {
    if (cast<StructType>(EltTy)->getNumElements() == 3)
      IsNewStructor = true;
    else
      IsOldStructor = true;
  }

  PointerType *VoidPtrTy = Type::getInt8Ty(SrcGV->getContext())->getPointerTo();
  if (IsOldStructor) {
    auto &ST = *cast<StructType>(EltTy);
    Type *Tys[3] = {ST.getElementType(0), ST.getElementType(1), VoidPtrTy};
    EltTy = StructType::get(SrcGV->getContext(), Tys, false);
  }

  uint64_t DstNumElements = 0;
  if (DstGV) {
    ArrayType *DstTy = cast<ArrayType>(DstGV->getValueType());
    DstNumElements = DstTy->getNumElements();

    if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage())
      return stringErr(
          "Linking globals named '" + SrcGV->getName() +
          "': can only link appending global with another appending "
          "global!");

    // Check to see that they two arrays agree on type.
    if (EltTy != DstTy->getElementType())
      return stringErr("Appending variables with different element types!");
    if (DstGV->isConstant() != SrcGV->isConstant())
      return stringErr("Appending variables linked with different const'ness!");

    if (DstGV->getAlignment() != SrcGV->getAlignment())
      return stringErr(
          "Appending variables with different alignment need to be linked!");

    if (DstGV->getVisibility() != SrcGV->getVisibility())
      return stringErr(
          "Appending variables with different visibility need to be linked!");

    if (DstGV->hasGlobalUnnamedAddr() != SrcGV->hasGlobalUnnamedAddr())
      return stringErr(
          "Appending variables with different unnamed_addr need to be linked!");

    if (DstGV->getSection() != SrcGV->getSection())
      return stringErr(
          "Appending variables with different section name need to be linked!");
  }

  SmallVector<Constant *, 16> SrcElements;
  getArrayElements(SrcGV->getInitializer(), SrcElements);

  if (IsNewStructor) {
    auto It = remove_if(SrcElements, [this](Constant *E) {
      auto *Key =
          dyn_cast<GlobalValue>(E->getAggregateElement(2)->stripPointerCasts());
      if (!Key)
        return false;
      GlobalValue *DGV = getLinkedToGlobal(Key);
      return !shouldLink(DGV, *Key);
    });
    SrcElements.erase(It, SrcElements.end());
  }
  uint64_t NewSize = DstNumElements + SrcElements.size();
  ArrayType *NewType = ArrayType::get(EltTy, NewSize);

  // Create the new global variable.
  GlobalVariable *NG = new GlobalVariable(
      DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
      /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
      SrcGV->getType()->getAddressSpace());

  NG->copyAttributesFrom(SrcGV);
  forceRenaming(NG, SrcGV->getName());

  Constant *Ret = ConstantExpr::getBitCast(NG, TypeMap.get(SrcGV->getType()));

  Mapper.scheduleMapAppendingVariable(*NG,
                                      DstGV ? DstGV->getInitializer() : nullptr,
                                      IsOldStructor, SrcElements);

  // Replace any uses of the two global variables with uses of the new
  // global.
  if (DstGV) {
    DstGV->replaceAllUsesWith(ConstantExpr::getBitCast(NG, DstGV->getType()));
    DstGV->eraseFromParent();
  }
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        continue;
      }
    }

    GlobalsToChange.push_back(G);
  }

  size_t n = GlobalsToChange.size();
  if (n == 0) return false;

  // A global is described by a structure
  //   size_t beg;
  //   size_t size;
  //   size_t size_with_redzone;
  //   const char *name;
  // We initialize an array of such structures and pass it to a run-time call.
  StructType *GlobalStructTy = StructType::get(IntptrTy, IntptrTy,
                                               IntptrTy, IntptrTy, NULL);
  SmallVector<Constant *, 16> Initializers(n);

  IRBuilder<> IRB(CtorInsertBefore);

  for (size_t i = 0; i < n; i++) {
    GlobalVariable *G = GlobalsToChange[i];
    PointerType *PtrTy = cast<PointerType>(G->getType());
    Type *Ty = PtrTy->getElementType();
    uint64_t SizeInBytes = TD->getTypeStoreSizeInBits(Ty) / 8;
    uint64_t RightRedzoneSize = RedzoneSize +
        (RedzoneSize - (SizeInBytes % RedzoneSize));
    Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);

    StructType *NewTy = StructType::get(Ty, RightRedZoneTy, NULL);
    Constant *NewInitializer = ConstantStruct::get(
        NewTy, G->getInitializer(),
        Constant::getNullValue(RightRedZoneTy), NULL);

    SmallString<2048> DescriptionOfGlobal = G->getName();
    DescriptionOfGlobal += " (";
    DescriptionOfGlobal += M.getModuleIdentifier();
    DescriptionOfGlobal += ")";
    GlobalVariable *Name = createPrivateGlobalForString(M, DescriptionOfGlobal);

    // Create a new global variable with enough space for a redzone.
    GlobalVariable *NewGlobal = new GlobalVariable(
        M, NewTy, G->isConstant(), G->getLinkage(),
        NewInitializer, "", G, G->isThreadLocal());
    NewGlobal->copyAttributesFrom(G);
    NewGlobal->setAlignment(RedzoneSize);

    Value *Indices2[2];
    Indices2[0] = IRB.getInt32(0);
    Indices2[1] = IRB.getInt32(0);

    G->replaceAllUsesWith(
        ConstantExpr::getGetElementPtr(NewGlobal, Indices2, true));
    NewGlobal->takeName(G);
    G->eraseFromParent();

    Initializers[i] = ConstantStruct::get(
        GlobalStructTy,
        ConstantExpr::getPointerCast(NewGlobal, IntptrTy),
        ConstantInt::get(IntptrTy, SizeInBytes),
        ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
        ConstantExpr::getPointerCast(Name, IntptrTy),
        NULL);
    DEBUG(dbgs() << "NEW GLOBAL:\n" << *NewGlobal);
  }

  ArrayType *ArrayOfGlobalStructTy = ArrayType::get(GlobalStructTy, n);
  GlobalVariable *AllGlobals = new GlobalVariable(
      M, ArrayOfGlobalStructTy, false, GlobalVariable::PrivateLinkage,
      ConstantArray::get(ArrayOfGlobalStructTy, Initializers), "");

  Function *AsanRegisterGlobals = cast<Function>(M.getOrInsertFunction(
      kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
  AsanRegisterGlobals->setLinkage(Function::ExternalLinkage);

  IRB.CreateCall2(AsanRegisterGlobals,
                  IRB.CreatePointerCast(AllGlobals, IntptrTy),
                  ConstantInt::get(IntptrTy, n));

  // We also need to unregister globals at the end, e.g. when a shared library
  // gets closed.
  Function *AsanDtorFunction = Function::Create(
      FunctionType::get(Type::getVoidTy(*C), false),
      GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
  BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
  IRBuilder<> IRB_Dtor(ReturnInst::Create(*C, AsanDtorBB));
  Function *AsanUnregisterGlobals = cast<Function>(M.getOrInsertFunction(
      kAsanUnregisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy, NULL));
  AsanUnregisterGlobals->setLinkage(Function::ExternalLinkage);

  IRB_Dtor.CreateCall2(AsanUnregisterGlobals,
                       IRB.CreatePointerCast(AllGlobals, IntptrTy),
                       ConstantInt::get(IntptrTy, n));
  appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndCtorPriority);

  DEBUG(dbgs() << M);
  return true;
}

std::unique_ptr<Module>
llvm::CloneSubModule(const Module &M,
                     HandleGlobalVariableFtor HandleGlobalVariable,
                     HandleFunctionFtor HandleFunction, bool KeepInlineAsm) {

  ValueToValueMapTy VMap;

  // First off, we need to create the new module.
  std::unique_ptr<Module> New =
      llvm::make_unique<Module>(M.getModuleIdentifier(), M.getContext());

  New->setDataLayout(M.getDataLayout());
  New->setTargetTriple(M.getTargetTriple());
  if (KeepInlineAsm)
    New->setModuleInlineAsm(M.getModuleInlineAsm());

  // Copy global variables (but not initializers, yet).
  for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I) {
    GlobalVariable *GV = new GlobalVariable(
        *New, I->getType()->getElementType(), I->isConstant(), I->getLinkage(),
        (Constant *)nullptr, I->getName(), (GlobalVariable *)nullptr,
        I->getThreadLocalMode(), I->getType()->getAddressSpace());
    GV->copyAttributesFrom(I);
    VMap[I] = GV;
  }

  // Loop over the functions in the module, making external functions as before
  for (Module::const_iterator I = M.begin(), E = M.end(); I != E; ++I) {
    Function *NF =
        Function::Create(cast<FunctionType>(I->getType()->getElementType()),
                         I->getLinkage(), I->getName(), &*New);
    NF->copyAttributesFrom(I);
    VMap[I] = NF;
  }

  // Loop over the aliases in the module
  for (Module::const_alias_iterator I = M.alias_begin(), E = M.alias_end();
       I != E; ++I) {
    auto *PTy = cast<PointerType>(I->getType());
    auto *GA =
        GlobalAlias::create(PTy->getElementType(), PTy->getAddressSpace(),
                            I->getLinkage(), I->getName(), &*New);
    GA->copyAttributesFrom(I);
    VMap[I] = GA;
  }

  // Now that all of the things that global variable initializer can refer to
  // have been created, loop through and copy the global variable referrers
  // over...  We also set the attributes on the global now.
  for (Module::const_global_iterator I = M.global_begin(), E = M.global_end();
       I != E; ++I) {
    GlobalVariable &GV = *cast<GlobalVariable>(VMap[I]);
    HandleGlobalVariable(GV, *I, VMap);
  }

  // Similarly, copy over function bodies now...
  //
  for (Module::const_iterator I = M.begin(), E = M.end(); I != E; ++I) {
    Function &F = *cast<Function>(VMap[I]);
    HandleFunction(F, *I, VMap);
  }

  // And aliases
  for (Module::const_alias_iterator I = M.alias_begin(), E = M.alias_end();
       I != E; ++I) {
    GlobalAlias *GA = cast<GlobalAlias>(VMap[I]);
    if (const Constant *C = I->getAliasee())
      GA->setAliasee(MapValue(C, VMap));
  }

  // And named metadata....
  for (Module::const_named_metadata_iterator I = M.named_metadata_begin(),
                                             E = M.named_metadata_end();
       I != E; ++I) {
    const NamedMDNode &NMD = *I;
    NamedMDNode *NewNMD = New->getOrInsertNamedMetadata(NMD.getName());
    for (unsigned i = 0, e = NMD.getNumOperands(); i != e; ++i)
      NewNMD->addOperand(MapMetadata(NMD.getOperand(i), VMap));
  }

  return New;
}

/// If there were any appending global variables, link them together now.
/// Return true on error.
Constant *IRLinker::linkAppendingVarProto(GlobalVariable *DstGV,
                                          const GlobalVariable *SrcGV) {
  Type *EltTy = cast<ArrayType>(TypeMap.get(SrcGV->getType()->getElementType()))
                    ->getElementType();

  StringRef Name = SrcGV->getName();
  bool IsNewStructor = false;
  bool IsOldStructor = false;
  if (Name == "llvm.global_ctors" || Name == "llvm.global_dtors") {
    if (cast<StructType>(EltTy)->getNumElements() == 3)
      IsNewStructor = true;
    else
      IsOldStructor = true;
  }

  PointerType *VoidPtrTy = Type::getInt8Ty(SrcGV->getContext())->getPointerTo();
  if (IsOldStructor) {
    auto &ST = *cast<StructType>(EltTy);
    Type *Tys[3] = {ST.getElementType(0), ST.getElementType(1), VoidPtrTy};
    EltTy = StructType::get(SrcGV->getContext(), Tys, false);
  }

  if (DstGV) {
    ArrayType *DstTy = cast<ArrayType>(DstGV->getType()->getElementType());

    if (!SrcGV->hasAppendingLinkage() || !DstGV->hasAppendingLinkage()) {
      emitError(
          "Linking globals named '" + SrcGV->getName() +
          "': can only link appending global with another appending global!");
      return nullptr;
    }

    // Check to see that they two arrays agree on type.
    if (EltTy != DstTy->getElementType()) {
      emitError("Appending variables with different element types!");
      return nullptr;
    }
    if (DstGV->isConstant() != SrcGV->isConstant()) {
      emitError("Appending variables linked with different const'ness!");
      return nullptr;
    }

    if (DstGV->getAlignment() != SrcGV->getAlignment()) {
      emitError(
          "Appending variables with different alignment need to be linked!");
      return nullptr;
    }

    if (DstGV->getVisibility() != SrcGV->getVisibility()) {
      emitError(
          "Appending variables with different visibility need to be linked!");
      return nullptr;
    }

    if (DstGV->hasUnnamedAddr() != SrcGV->hasUnnamedAddr()) {
      emitError(
          "Appending variables with different unnamed_addr need to be linked!");
      return nullptr;
    }

    if (StringRef(DstGV->getSection()) != SrcGV->getSection()) {
      emitError(
          "Appending variables with different section name need to be linked!");
      return nullptr;
    }
  }

  SmallVector<Constant *, 16> DstElements;
  if (DstGV)
    getArrayElements(DstGV->getInitializer(), DstElements);

  SmallVector<Constant *, 16> SrcElements;
  getArrayElements(SrcGV->getInitializer(), SrcElements);

  if (IsNewStructor)
    SrcElements.erase(
        std::remove_if(SrcElements.begin(), SrcElements.end(),
                       [this](Constant *E) {
                         auto *Key = dyn_cast<GlobalValue>(
                             E->getAggregateElement(2)->stripPointerCasts());
                         if (!Key)
                           return false;
                         GlobalValue *DGV = getLinkedToGlobal(Key);
                         return !shouldLink(DGV, *Key);
                       }),
        SrcElements.end());
  uint64_t NewSize = DstElements.size() + SrcElements.size();
  ArrayType *NewType = ArrayType::get(EltTy, NewSize);

  // Create the new global variable.
  GlobalVariable *NG = new GlobalVariable(
      DstM, NewType, SrcGV->isConstant(), SrcGV->getLinkage(),
      /*init*/ nullptr, /*name*/ "", DstGV, SrcGV->getThreadLocalMode(),
      SrcGV->getType()->getAddressSpace());

  NG->copyAttributesFrom(SrcGV);
  forceRenaming(NG, SrcGV->getName());

//.........这里部分代码省略.........