Measurement of Virtual Function Call Overhead on Modern Processors

In this section we measure the direct cost of virtual function table lookup for a number of realistic C++ programs running on superscalar processors employing co-scheduling and simple indirect branch prediction, and identify the processor characteristics that most affect this cost. In Section 5.2 we saw that, when analyzed in isolation, the cost of dispatch sequences of table-based techniques are similar to virtual function tables. Therefore VTBL serves as a representative technique for table-based dispatch in this quantitative analysis.