Quicksilver: A quasi-static compiler for Java

Abstract

This paper presents the design and implementation of the Quicksilver1 quasi-static compiler for Java. Quasi-static compilation is a new approach that combines the benefits of static and dynamic compilation, while maintaining compliance with the Java standard, including support of its dynamic features. A quasi-static compiler relies on the generation and reuse of persistent code images to reduce the overhead of compilation during program execution, and to provide identical, testable and reliable binaries over different program executions. At runtime, the quasi-static compiler adapts pre-compiled binaries to the current JVM instance, and uses dynamic compilation of the code when necessary to support dynamic Java features. Our system allows interprocedural program optimizations to be performed while maintaining binary compatibility. Experimental data obtained using a preliminary implementation of a quasi-static compiler in the Jalapeno JVM clearly demonstrates the benefits of our approach: we achieve a runtime compilation cost comparable to that of baseline (fast, non-optimizing) compilation, and deliver the runtime program performance of the highest optimization level supported by the Jalapeno optimizing compiler. For the SPECjvm98 benchmark suite, we obtain a factor of 104 to 158 reduction in the runtime compilation overhead relative to the Jalapeño optimizing compiler. Relative to the better of the baseline and the optimizing Jalapeño compilers, the overall performance (taking into account both runtime compilation and execution costs) is increased by 9.2% to 91.4% for the SPECjvm98 benchmarks with size 100, and by 54% to 356% for the (shorter running) SPECjvm98 benchmarks with size 10. © 2000 ACM.