Two-level Just-in-Time Compilation with One Interpreter and One Engine

Modern, powerful virtual machines such as those running Java or JavaScript support multi-tier JIT compilation and optimization features to achieve their high performance. However, implementing and maintaining several compilers/optimizers that interact with each other requires hard-working VM developers. In this paper, we propose a technique to realize two-level JIT compilation in RPython without implementing several interpreters or compilers from scratch. As a preliminary realization, we created adaptive RPython, which performs both baseline JIT compilation based on threaded code and tracing JIT compilation. We also implemented a small programming language with it. Furthermore, we preliminarily evaluated the performance of that small language, and our baseline JIT compilation ran 1.77x faster than the interpreter-only execution. Furthermore, we observed that when we apply an optimal JIT compilation for different target methods, the performance was mostly the same as the one optimizing JIT compilation strategy, saving about 40 % of the compilation code size.