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

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.........