Fast object-oriented procedure calls: lessons from the Intel 432

Abstract

As modular programming grows in importance, the efficiency of procedure calls assumes an ever more critical role in system performance. Meanwhile, software designers are becoming more aware of the benefits of object-oriented programming in structuring large software systems. But object-oriented programming requires a good deal of support, which can best be distributed between the compiler and architectural levels. A major part of this support relates to the execution of procedure calls. Must such support exact an unacceptable performance penalty? By considering the case of the Intel 432, a prominent object-oriented architecture, we argue that it need not. The 432 provided all the facilities needed to support object orientation. Though its procedure call was slow, the reasons were only tenuously related to object orientation. Most of the inefficiency could be removed in future designs by the adoption of a few new mechanisms: stack-based allocation of contexts, a memory-clearing coprocessor, and the use of multiple register sets to hold addressing information. These proposals offer the prospect of an object-oriented procedure call that can, on average, be performed nearly as fast as an ordinary unprotected procedure call.