A Stack Hybridization for Meta-hybrid Just-in-time Compilation

Meta-interpreter-based language implementation frameworks, such as RPython and Truffe/Graal, are convenient tool for implementing state-of-the-art virtual machines. Those frameworks are classified into trace-based and method- (or ast-) based strategies. RPython uses a trace-based policy to compile straight execution paths, while Truffe/Graal leverages method invocation to compile entire method bodies. Each approach has its own advantages and disadvantages. The trace-based strategy is good at compiling pro- grams with many branching possibilities and able to reduce the size of compiled code, but it is weak at programs with varying control-flow. The method-based strategy is robust with the latter type of programs but it needs thorough method-inlining management to achieve excellent performance. To take advantage of both strategies, we propose a meta-hybrid compilation technique to integrate trace- and method-based compilations, as well as a proof-of-concept implementation called BacCaml. To achieve this goal, we develop a stack hybridization mechanism which makes it possible to coordinate trace- and method-based meta JIT compilation. In the implementation, we extend RPython’s architecture and introduced a special syntax for realizing this system in a single interpreter definition.