Design of Multilingual Retargetable Compilers: Experience of the XDS Framework Evolution

The XDS framework has been developed since 1993. During this time, it has been serving as a production compiler construction framework as well as a base for research projects. Completely written in Oberon-2, XDS uses a mixed design technique amalgamating modular and object-oriented approaches. It combines advantages of both approaches, at the same time avoiding drawbacks inherent to each of them if used separately. In this paper we set out how the mixed design approach contributes to extensibility of the framework with respect to including support for new input languages and target architectures and implementing new optimizations. In the first part of the paper we give an overview of the XDS framework architecture emphasizing which parts are worth applying the object-oriented design. In the second part, we describe our experience of extending XDS with support for the Java language and implementing interprocedural and object-oriented optimizations.