C++ AttributeList::getRetAttributes方法代码示例

// Clone OldFunc into NewFunc, transforming the old arguments into references to
// VMap values.
//
void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
                             ValueToValueMapTy &VMap,
                             bool ModuleLevelChanges,
                             SmallVectorImpl<ReturnInst*> &Returns,
                             const char *NameSuffix, ClonedCodeInfo *CodeInfo,
                             ValueMapTypeRemapper *TypeMapper,
                             ValueMaterializer *Materializer) {
  assert(NameSuffix && "NameSuffix cannot be null!");

#ifndef NDEBUG
  for (const Argument &I : OldFunc->args())
    assert(VMap.count(&I) && "No mapping from source argument specified!");
#endif

  // Copy all attributes other than those stored in the AttributeList.  We need
  // to remap the parameter indices of the AttributeList.
  AttributeList NewAttrs = NewFunc->getAttributes();
  NewFunc->copyAttributesFrom(OldFunc);
  NewFunc->setAttributes(NewAttrs);

  // Fix up the personality function that got copied over.
  if (OldFunc->hasPersonalityFn())
    NewFunc->setPersonalityFn(
        MapValue(OldFunc->getPersonalityFn(), VMap,
                 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
                 TypeMapper, Materializer));

  SmallVector<AttributeSet, 4> NewArgAttrs(NewFunc->arg_size());
  AttributeList OldAttrs = OldFunc->getAttributes();

  // Clone any argument attributes that are present in the VMap.
  for (const Argument &OldArg : OldFunc->args()) {
    if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
      NewArgAttrs[NewArg->getArgNo()] =
          OldAttrs.getParamAttributes(OldArg.getArgNo());
    }
  }

  NewFunc->setAttributes(
      AttributeList::get(NewFunc->getContext(), OldAttrs.getFnAttributes(),
                         OldAttrs.getRetAttributes(), NewArgAttrs));

  bool MustCloneSP =
      OldFunc->getParent() && OldFunc->getParent() == NewFunc->getParent();
  DISubprogram *SP = OldFunc->getSubprogram();
  if (SP) {
    assert(!MustCloneSP || ModuleLevelChanges);
    // Add mappings for some DebugInfo nodes that we don't want duplicated
    // even if they're distinct.
    auto &MD = VMap.MD();
    MD[SP->getUnit()].reset(SP->getUnit());
    MD[SP->getType()].reset(SP->getType());
    MD[SP->getFile()].reset(SP->getFile());
    // If we're not cloning into the same module, no need to clone the
    // subprogram
    if (!MustCloneSP)
      MD[SP].reset(SP);
  }

  SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
  OldFunc->getAllMetadata(MDs);
  for (auto MD : MDs) {
    NewFunc->addMetadata(
        MD.first,
        *MapMetadata(MD.second, VMap,
                     ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
                     TypeMapper, Materializer));
  }

  // When we remap instructions, we want to avoid duplicating inlined
  // DISubprograms, so record all subprograms we find as we duplicate
  // instructions and then freeze them in the MD map.
  DebugInfoFinder DIFinder;

  // Loop over all of the basic blocks in the function, cloning them as
  // appropriate.  Note that we save BE this way in order to handle cloning of
  // recursive functions into themselves.
  //
  for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
       BI != BE; ++BI) {
    const BasicBlock &BB = *BI;

    // Create a new basic block and copy instructions into it!
    BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo,
                                      SP ? &DIFinder : nullptr);

    // Add basic block mapping.
    VMap[&BB] = CBB;

    // It is only legal to clone a function if a block address within that
    // function is never referenced outside of the function.  Given that, we
    // want to map block addresses from the old function to block addresses in
    // the clone. (This is different from the generic ValueMapper
    // implementation, which generates an invalid blockaddress when
    // cloning a function.)
    if (BB.hasAddressTaken()) {
      Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
//.........这里部分代码省略.........

//.........这里部分代码省略.........
        Params.push_back(GetElementPtrInst::getIndexedType(
            cast<PointerType>(I->getType()->getScalarType())->getElementType(),
            ArgIndex.second));
        ArgAttrVec.push_back(AttributeSet());
        assert(Params.back());
      }

      if (ArgIndices.size() == 1 && ArgIndices.begin()->second.empty())
        ++NumArgumentsPromoted;
      else
        ++NumAggregatesPromoted;
    }
  }

  Type *RetTy = FTy->getReturnType();

  // Construct the new function type using the new arguments.
  FunctionType *NFTy = FunctionType::get(RetTy, Params, FTy->isVarArg());

  // Create the new function body and insert it into the module.
  Function *NF = Function::Create(NFTy, F->getLinkage(), F->getName());
  NF->copyAttributesFrom(F);

  // Patch the pointer to LLVM function in debug info descriptor.
  NF->setSubprogram(F->getSubprogram());
  F->setSubprogram(nullptr);

  DEBUG(dbgs() << "ARG PROMOTION:  Promoting to:" << *NF << "\n"
               << "From: " << *F);

  // Recompute the parameter attributes list based on the new arguments for
  // the function.
  NF->setAttributes(AttributeList::get(F->getContext(), PAL.getFnAttributes(),
                                       PAL.getRetAttributes(), ArgAttrVec));
  ArgAttrVec.clear();

  F->getParent()->getFunctionList().insert(F->getIterator(), NF);
  NF->takeName(F);

  // Loop over all of the callers of the function, transforming the call sites
  // to pass in the loaded pointers.
  //
  SmallVector<Value *, 16> Args;
  while (!F->use_empty()) {
    CallSite CS(F->user_back());
    assert(CS.getCalledFunction() == F);
    Instruction *Call = CS.getInstruction();
    const AttributeList &CallPAL = CS.getAttributes();

    // Loop over the operands, inserting GEP and loads in the caller as
    // appropriate.
    CallSite::arg_iterator AI = CS.arg_begin();
    ArgNo = 0;
    for (Function::arg_iterator I = F->arg_begin(), E = F->arg_end(); I != E;
         ++I, ++AI, ++ArgNo)
      if (!ArgsToPromote.count(&*I) && !ByValArgsToTransform.count(&*I)) {
        Args.push_back(*AI); // Unmodified argument
        ArgAttrVec.push_back(CallPAL.getParamAttributes(ArgNo));
      } else if (ByValArgsToTransform.count(&*I)) {
        // Emit a GEP and load for each element of the struct.
        Type *AgTy = cast<PointerType>(I->getType())->getElementType();
        StructType *STy = cast<StructType>(AgTy);
        Value *Idxs[2] = {
            ConstantInt::get(Type::getInt32Ty(F->getContext()), 0), nullptr};
        for (unsigned i = 0, e = STy->getNumElements(); i != e; ++i) {
          Idxs[1] = ConstantInt::get(Type::getInt32Ty(F->getContext()), i);