Techreport,
QuickInterp - Improving interpreter performance with superinstructions
(June 2020)
Abstract
The performance of Java Virtual Machine bytecode interpreters can be severely limited by the (1) inability to perform optimizations over multiple instructions, and (2) the excessive level of branching with the interpreter loop as a result of having to do at least one jump per bytecode instruction. With the QuickInterp VM we mitigate these performance limitations within JVM interpreter design by means of superinstructions. Bytecode is, at class load time, preprocessed where sequences of bytecode instructions are replaced by such equivalent superinstructions, requiring no alterations to or compatibility loss with existing bytecode. The interpreter source code is generated automatically based on a profile of the running application.
Our methods show that the superinstruction optimization is still valid in 2020, boasting a 45.6% performance improvement against baseline in a small arithmetic benchmark, and showing a 33.0% improvement against baseline in a larger Spring Boot-based web application benchmark. Our iterative superinstruction set construction algorithm manages to find near-optimal solutions for the NP-hard problem of constructing the superinstruction set. However, we also show how more advanced superinstruction placement algorithms do not offer the same return on investment. Given enough superinstructions, each of the tested substitution algorithms is capable of achieving similar performance improvements.
