Publications

In recent years, compositional symbolic execution (CSE) tools have been growing in prominence and are becoming more and more applicable to real-world codebases. Still to this day, however, debugging the output of these tools remains difficult, even for specialist users. To address this, we introduce a debugging interface for symbolic execution tools, integrated with Visual Studio Code and the Gillian multi-language CSE platform, with strong focus on visualisation, interactivity, and intuitive representation of symbolic execution trees. We take care in making this interface tool-agnostic, easing its transfer to other symbolic analysis tools in future. We empirically evaluate our work with a user study, the results of which show the debugger's usefulness in helping early researchers understand the principles of CSE and verify fundamental data structure algorithms in Gillian.

Software debugging for concrete execution enjoys a mature suite of tools, but debugging symbolic execution is still in its infancy. It carries unique challenges, as a single state can lead to multiple branches representing different sets of conditions, and symbolic states must be 'matched' against logical conditions. Some of today's otherwise mature symbolic-execution tools still rely on plain-text log files for debugging, which provide no good overview of the execution process and can quickly become overwhelming. We introduce a debugger for Gillian's verification mode—complete with a custom interface—and ponder the potential for this interface and the protocol behind it to be used outside of Gillian.