Measurement and Application of Dynamic Receiver Class Distributions

Dynamic binding slows down object-oriented programs. Dynamic dispatch mechanisms which work well where all receiver classes are equally likely are too pessimistic because at most call sites one receiver class predominates. We apply dynamic profile information to determine the dynamic execution frequency distributions of the classes of receivers at call sites. We show that these distributions are heavily skewed towards the most commonly occurring receiver class across several different languages. Moreover, we show that the distributions are stable across program inputs, from one version of a program to another, and even to some extent across programs that share library code. Finally, we demonstrate that significant run-time performance improvements for object-oriented programs can be gained by exploiting the information contained in dynamic receiver class distributions in a relatively simple optimizing compiler.