C++ iterator::use_empty方法代码示例

bool PartialInliner::runOnModule(Module& M) {
  std::vector<Function*> worklist;
  worklist.reserve(M.size());
  for (Module::iterator FI = M.begin(), FE = M.end(); FI != FE; ++FI)
    if (!FI->use_empty() && !FI->isDeclaration())
      worklist.push_back(&*FI);
    
  bool changed = false;
  while (!worklist.empty()) {
    Function* currFunc = worklist.back();
    worklist.pop_back();
  
    if (currFunc->use_empty()) continue;
    
    bool recursive = false;
    for (Function::use_iterator UI = currFunc->use_begin(),
         UE = currFunc->use_end(); UI != UE; ++UI)
      if (Instruction* I = dyn_cast<Instruction>(*UI))
        if (I->getParent()->getParent() == currFunc) {
          recursive = true;
          break;
        }
    if (recursive) continue;
          
    
    if (Function* newFunc = unswitchFunction(currFunc)) {
      worklist.push_back(newFunc);
      changed = true;
    }
    
  }
  
  return changed;
}

bool StripExternals::runOnModule(Module &M) {
  bool Changed = false;

  for (Module::iterator I = M.begin(); I != M.end(); ) {
    if (I->hasAvailableExternallyLinkage()) {
      assert(!I->isDeclaration()&&"Declarations can't be available_externally");
      Changed = true;
      ++NumFunctions;
      if (I->use_empty()) {
        DEBUG(errs() << "Deleting function: " << *I);
        Module::iterator todelete = I;
        ++I;
        todelete->eraseFromParent();
        continue;
      } else {
        I->deleteBody();
        DEBUG(errs() << "Deleted function body: " << *I);
      }
    }
    ++I;
  }

  for (Module::global_iterator I = M.global_begin();
       I != M.global_end(); ) {
    if (I->hasAvailableExternallyLinkage()) {
      assert(!I->isDeclaration()&&"Declarations can't be available_externally");
      Changed = true;
      ++NumVariables;
      if (I->use_empty()) {
        DEBUG(errs() << "Deleting global: " << *I);
        Module::global_iterator todelete = I;
        ++I;
        todelete->eraseFromParent();
        continue;
      } else {
        I->setInitializer(0);
        I->setLinkage(GlobalValue::ExternalLinkage);
        DEBUG(errs() << "Deleted initializer: " << *I);
      }
    }
    ++I;
  }

  return Changed;
}

void IntrinsicLowering::AddPrototypes(Module &M) {
  LLVMContext &Context = M.getContext();
  for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
    if (I->isDeclaration() && !I->use_empty())
      switch (I->getIntrinsicID()) {
      default: break;
      case Intrinsic::setjmp:
        EnsureFunctionExists(M, "setjmp", I->arg_begin(), I->arg_end(),
                             Type::getInt32Ty(M.getContext()));
        break;
      case Intrinsic::longjmp:
        EnsureFunctionExists(M, "longjmp", I->arg_begin(), I->arg_end(),
                             Type::getVoidTy(M.getContext()));
        break;
      case Intrinsic::siglongjmp:
        EnsureFunctionExists(M, "abort", I->arg_end(), I->arg_end(),
                             Type::getVoidTy(M.getContext()));
        break;
      case Intrinsic::memcpy:
        M.getOrInsertFunction("memcpy",
          Type::getInt8PtrTy(Context),
                              Type::getInt8PtrTy(Context), 
                              Type::getInt8PtrTy(Context), 
                              DL.getIntPtrType(Context), nullptr);
        break;
      case Intrinsic::memmove:
        M.getOrInsertFunction("memmove",
          Type::getInt8PtrTy(Context),
                              Type::getInt8PtrTy(Context), 
                              Type::getInt8PtrTy(Context), 
                              DL.getIntPtrType(Context), nullptr);
        break;
      case Intrinsic::memset:
        M.getOrInsertFunction("memset",
          Type::getInt8PtrTy(Context),
                              Type::getInt8PtrTy(Context), 
                              Type::getInt32Ty(M.getContext()), 
                              DL.getIntPtrType(Context), nullptr);
        break;
      case Intrinsic::sqrt:
        EnsureFPIntrinsicsExist(M, I, "sqrtf", "sqrt", "sqrtl");
        break;
      case Intrinsic::sin:
        EnsureFPIntrinsicsExist(M, I, "sinf", "sin", "sinl");
        break;
      case Intrinsic::cos:
        EnsureFPIntrinsicsExist(M, I, "cosf", "cos", "cosl");
        break;
      case Intrinsic::pow:
        EnsureFPIntrinsicsExist(M, I, "powf", "pow", "powl");
        break;
      case Intrinsic::log:
        EnsureFPIntrinsicsExist(M, I, "logf", "log", "logl");
        break;
      case Intrinsic::log2:
        EnsureFPIntrinsicsExist(M, I, "log2f", "log2", "log2l");
        break;
      case Intrinsic::log10:
        EnsureFPIntrinsicsExist(M, I, "log10f", "log10", "log10l");
        break;
      case Intrinsic::exp:
        EnsureFPIntrinsicsExist(M, I, "expf", "exp", "expl");
        break;
      case Intrinsic::exp2:
        EnsureFPIntrinsicsExist(M, I, "exp2f", "exp2", "exp2l");
        break;
      }
}

/// CleanupAndPrepareModules - Get the specified modules ready for code
/// generator testing.
///
static void CleanupAndPrepareModules(BugDriver &BD, Module *&Test,
                                     Module *Safe) {
  // Clean up the modules, removing extra cruft that we don't need anymore...
  Test = BD.performFinalCleanups(Test);

  // If we are executing the JIT, we have several nasty issues to take care of.
  if (!BD.isExecutingJIT()) return;

  // First, if the main function is in the Safe module, we must add a stub to
  // the Test module to call into it.  Thus, we create a new function `main'
  // which just calls the old one.
  if (Function *oldMain = Safe->getFunction("main"))
    if (!oldMain->isDeclaration()) {
      // Rename it
      oldMain->setName("llvm_bugpoint_old_main");
      // Create a NEW `main' function with same type in the test module.
      Function *newMain = Function::Create(oldMain->getFunctionType(),
                                           GlobalValue::ExternalLinkage,
                                           "main", Test);
      // Create an `oldmain' prototype in the test module, which will
      // corresponds to the real main function in the same module.
      Function *oldMainProto = Function::Create(oldMain->getFunctionType(),
                                                GlobalValue::ExternalLinkage,
                                                oldMain->getName(), Test);
      // Set up and remember the argument list for the main function.
      std::vector<Value*> args;
      for (Function::arg_iterator
             I = newMain->arg_begin(), E = newMain->arg_end(),
             OI = oldMain->arg_begin(); I != E; ++I, ++OI) {
        I->setName(OI->getName());    // Copy argument names from oldMain
        args.push_back(I);
      }

      // Call the old main function and return its result
      BasicBlock *BB = BasicBlock::Create(Safe->getContext(), "entry", newMain);
      CallInst *call = CallInst::Create(oldMainProto, args.begin(), args.end(),
                                        "", BB);

      // If the type of old function wasn't void, return value of call
      ReturnInst::Create(Safe->getContext(), call, BB);
    }

  // The second nasty issue we must deal with in the JIT is that the Safe
  // module cannot directly reference any functions defined in the test
  // module.  Instead, we use a JIT API call to dynamically resolve the
  // symbol.

  // Add the resolver to the Safe module.
  // Prototype: void *getPointerToNamedFunction(const char* Name)
  Constant *resolverFunc =
    Safe->getOrInsertFunction("getPointerToNamedFunction",
                    Type::getInt8PtrTy(Safe->getContext()),
                    Type::getInt8PtrTy(Safe->getContext()),
                       (Type *)0);

  // Use the function we just added to get addresses of functions we need.
  for (Module::iterator F = Safe->begin(), E = Safe->end(); F != E; ++F) {
    if (F->isDeclaration() && !F->use_empty() && &*F != resolverFunc &&
        !F->isIntrinsic() /* ignore intrinsics */) {
      Function *TestFn = Test->getFunction(F->getName());

      // Don't forward functions which are external in the test module too.
      if (TestFn && !TestFn->isDeclaration()) {
        // 1. Add a string constant with its name to the global file
        Constant *InitArray = ConstantArray::get(F->getContext(), F->getName());
        GlobalVariable *funcName =
          new GlobalVariable(*Safe, InitArray->getType(), true /*isConstant*/,
                             GlobalValue::InternalLinkage, InitArray,
                             F->getName() + "_name");

        // 2. Use `GetElementPtr *funcName, 0, 0' to convert the string to an
        // sbyte* so it matches the signature of the resolver function.

        // GetElementPtr *funcName, ulong 0, ulong 0
        std::vector<Constant*> GEPargs(2,
                     Constant::getNullValue(Type::getInt32Ty(F->getContext())));
        Value *GEP =
                ConstantExpr::getGetElementPtr(funcName, &GEPargs[0], 2);
        std::vector<Value*> ResolverArgs;
        ResolverArgs.push_back(GEP);

        // Rewrite uses of F in global initializers, etc. to uses of a wrapper
        // function that dynamically resolves the calls to F via our JIT API
        if (!F->use_empty()) {
          // Create a new global to hold the cached function pointer.
          Constant *NullPtr = ConstantPointerNull::get(F->getType());
          GlobalVariable *Cache =
            new GlobalVariable(*F->getParent(), F->getType(), 
                               false, GlobalValue::InternalLinkage,
                               NullPtr,F->getName()+".fpcache");

          // Construct a new stub function that will re-route calls to F
          const FunctionType *FuncTy = F->getFunctionType();
          Function *FuncWrapper = Function::Create(FuncTy,
                                                   GlobalValue::InternalLinkage,
                                                   F->getName() + "_wrapper",
                                                   F->getParent());
//.........这里部分代码省略.........