Cross-Language Call Graph Construction Supporting Different Host Languages

Abstract

Modern software systems are increasingly multi-lingual, which consist of components developed in different programming languages to reuse existing libraries and com-bine language features. Foreign function interface (FFI) is a mechanism that enables interoperation between a host language and a guest language. CFFI interoperating with external C is part of the language standard for almost all languages. For example, Python/C API is the CFFI between Python and C/C++. Python host with C guest can achieve both productivity and performance, and is widely used by many mainstream software systems in different application domains. The popularity of these software systems makes high demands on program analysis of multilingual codebases. A fundamental challenge is to construct call graphs that capture the connectivity between host and guest languages. In this work, we present a novel approach to call graph construction for calls from different host languages to C/C++ foreign functions. The semantics of the foreign function declaration interfaces are modeled to establish cross-language call relationships, taking into account the semantic abstraction to support different host languages. Graph transformation and function node fusions are defined to build the complete call graphs. We demonstrate experimentally that static call graphs for Python and JavaScript calling C/C++ can be constructed effectively and automatically. The call graph construction can further efficiently work as an IDE language server and integrate with other tools.