Context-Aware Program Simplification to Improve Information Retrieval-Based Bug Localization

Information Retrieval-based Bug localization (IRBL) techniques have become a hot research topic in bug localization due to their few external dependencies and low execution cost. However, existing IRBL techniques have many challenges regarding localization granularity and applicability. First, existing IRBL techniques have not yet achieved statement-level bug localization. Second, almost all studies are limited to Java-based projects, and the effectiveness of these techniques for other widely used programming languages (e.g., Python) is still unknown. The reason for these deficiencies is that existing IRBL techniques mainly employ conventional NLP techniques to analyze the bug reports and have not yet fully exploited the stack trace attached to the bug reports. To improve IRBL techniques in terms of localization granularity and adaptability, we propose a context-aware program simplification technique—COPS—that is able to localize defective statements in suspicious files by analyzing the stack trace in bug reports, which enables statement-level bug localization for Python-based projects. Experiments using 948 bug reports show that our technique can localize the buggy statements with 102.6% higher Top@10, 56.2% higher MAP@10, and 95.6% higher MRR@10 than the baseline. Compared with the state-of-the-art techniques, COPS can improve 19.1% in MAP@10 and achieve 92% buggy statement coverage with a full scope search. Experimental results show that COPS has higher bug localization effectiveness than existing IRBL techniques; and that COPS achieves the same effectiveness with higher execution efficiency than state-of-the-art statement-level defect techniques.