Generating Java Compiler Optimizers Using Bidirectional CTL

Abstract

There have been several research works that analyze and optimize programs using temporal logic. However, no evaluation of optimization time or execution time of these implementations has been done for any real programming language. In this paper, we present a system that generates a Java optimizer from specifications in temporal logic. The specification is simpler, and the generated optimizers run more efficiently than previously reported work. We implemented a new model checker for a bidirectional CTL (computational tree logic) called CTLbd, which is equivalent to CTL-FV [Lacey, D., Jones, N.D., Van Wyk, E. and Frederiksen, C.C.: Compiler optimization correctness by temporal logic. Higher-Order and Symbolic Computation, Vol. 17, No. 3, pp. 173–206, 2004] after removing free variables. The model checker can check future and past temporal CTL operators symmetrically without any conversion. We also present a new specification language based on the bidirectional CTL that can express typical optimization rules very naturally. By adding rewriting conditions to allow for temporary variables and considering real-world language features such as exceptions, the system can perform optimization of Java programs. So far, a compiler optimizer using temporal logic was assumed to be impractical, because it consumes too much time. However, with our method, the generated Java compiler optimizer can compile seven of the SPECjvm98 benchmarks with a compile time from 4 seconds to 4 minutes.