Accurate program analyses for successful specialization of legacy system software

Choosing the accuracy of program analyses is a crucial issue when designing and developing a partial evaluator capable of treating realistic programs, and in particular legacy software. In this paper, we investigate the degree of accuracy of alias and binding-time analyses that is required to successfully exploit the specialization opportunities present in the Sun commercial implementation of the remote procedure call protocol (RPC). The Sun RPC implementation consists of a stack of small parameterized layers. This structure is representative of a certain programming style in operating system and network development. The analysis features that we have explored have been implemented in Tempo, a partial evaluator for C. After automatic specialization of the RPC using Tempo, we measured speedups up to 1.5 for complete remote procedure calls (including network transport) and up to 3.7 for local buffer encoding alone. This experiment suggests that partial evaluation is reaching a high level of maturity.