how to get memory value read or written in user defined function of a executable without symbol information with Intel Pin?

Question

I want to get memory value records read or written by user defined function of one executable without symbol information with Intel Pin.because there is no symbol information Intel pin can not identify the scope of function(mainly user defined function),so routine level instrument does not work.:),so only instruction level instruction can be chosen, but how to connect each instruction with one function. for example I want get memory read or written by "getSum", can anyone provide any information? thanks.:)

int getSum()
{
   int sum = 0;

   for(int i = 1 ; i <= 10;i++){
       sum += i;
   }
   return sum;
}