Automatically Generated Supernodes for AST Interpreters Improve Virtual-Machine Performance

Abstract syntax tree (AST) interpreters allow implementing programming languages in a straight-forward way. However, AST interpreters implemented in object-oriented languages, such as e.g. in Java, often suffer from two serious performance issues. First, these interpreters commonly implement AST nodes by leveraging class inheritance and polymorphism, leading to many polymorphic call sites in the interpreter implementation and hence lowering interpreter performance. Second, widely used implementations of these interpreters throw costly runtime exceptions to model the control flow. Even though Just-in-Time (JIT) compilation mitigates these issues, performance in the first stages of the program execution remains poor.