OPT_PhysicalRegisterSet phys = ir.regpool.getPhysicalRegisterSet();
  void replaceOperandWithSpillLocation(OPT_Instruction s,                                                OPT_RegisterOperand symb) {    // Get the spill location previously assigned to the symbolic    // register.    int location = OPT_RegisterAllocatorState.getSpill(symb.register);    // Create a memory operand M representing the spill location.    OPT_PhysicalRegisterSet phys = ir.regpool.getPhysicalRegisterSet();    OPT_Operand M = null;    int type = OPT_PhysicalRegisterSet.getPhysicalRegisterType(symb.register);    int size = OPT_PhysicalRegisterSet.getSpillSize(type);    M = new OPT_StackLocationOperand(true, -location, (byte)size);    // replace the register operand with the memory operand    s.replaceOperand(symb,M);  }