DEPARTMENT OF COMPUTER SCIENCE
DOCTORAL DISSERTATION DEFENSE


Candidate: Chung Yung
Advisor: Benjamin Goldberg

Destructive Effect Analysis And Finite Differencing For Strict Functional Languages

10:00 a.m., Friday, August 6, 1999
7th floor conference room, 715 Broadway




Abstract

Destructive update optimization is critical for writing scientific codes in functional languages. Pure functional languages do not allow mutations, destructive updates, or selective updates so that the straightforward implementations of functional languages induces large amounts of copying to preserve program semantics. The unnecessary copying of data can increase both the execution time and the memory requirements of an application. Destructive update optimization makes an essential improvement to the implementation of functional programs with compound data structures, such as arrays, sets, and aggregates. Moreover, for many of the compiler optimization techniques that depend on the side-effects, destructive update analysis provide the input for applying such optimization techniques. Among other compiler optimization techniques, finite differencing captures common yet distinctive program constructions of costly repeated calculations and transforms them into more efficient incremental program constructions.

In this dissertation, we develop a new approach to destructive update analysis, called destructive effect analysis. We present the semantic model and the abstract interpretation of destructive effect analysis. We designed EAS, an experimental applicative language with set expressions. The implementation of the destructive effect analysis is integrated with the optimization phase of our experimental compiler of EAS. We apply finite differencing to optimize pure functional programs, and we show the performance improvement that results from applying the finite differencing optimization together with the destructive update optimization.