static X86MachineFunctionInfo calculateFunctionInfo(const Function *F,
                                                    const TargetData *TD) {
  X86MachineFunctionInfo Info;
  uint64_t Size = 0;

  switch (F->getCallingConv()) {
  case CallingConv::X86_StdCall:
    Info.setDecorationStyle(StdCall);
    break;
  case CallingConv::X86_FastCall:
    Info.setDecorationStyle(FastCall);
    break;
  default:
    return Info;
  }

  unsigned argNum = 1;
  for (Function::const_arg_iterator AI = F->arg_begin(), AE = F->arg_end();
       AI != AE; ++AI, ++argNum) {
    const Type* Ty = AI->getType();

    // 'Dereference' type in case of byval parameter attribute
    if (F->paramHasAttr(argNum, Attribute::ByVal))
      Ty = cast<PointerType>(Ty)->getElementType();

    // Size should be aligned to DWORD boundary
    Size += ((TD->getTypePaddedSize(Ty) + 3)/4)*4;
  }

  // We're not supporting tooooo huge arguments :)
  Info.setBytesToPopOnReturn((unsigned int)Size);
  return Info;
}