Optimizing Dynamically-Dispatched Calls with Run-Time Type Feedback

Urs Hölzle and David Ungar

Abstract: Object-oriented programs are difficult to optimize because they execute many dynamically-dispatched calls. These calls cannot easily be eliminated because the compiler does not know which callee will be invoked at runtime. We have developed a simple technique that feeds back type information from the runtime system to the compiler. With this type feedback, the compiler can inline any dynamically-dispatched call. Our compiler drastically reduces the call frequency of a suite of large SELF applications (by a factor of 3.6) and improves performance by a factor of 1.7. We believe that type feedback could significantly reduce call frequencies and improve performance for most other object-oriented languages (statically-typed or not) as well as for languages with type-dependent operations such as generic arithmetic.

Proceedings of the ACM SIGPLAN `94 Conference on Programming Language Design and Implementation.

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