A Probabilistic Delta Debugging Approach for Abstract Syntax Trees

Delta debugging provides an efficient and systematic approach to isolate and identify a minimal subsequence that exhibit a specific property. A notable trend in the development of delta debugging is to address data with domain-specific structures, such as programs. However, the efficiency and effectiveness of domain-specific delta debugging algorithms still present challenges. Probabilistic delta debugging (ProbDD) enhances the ddmin algorithm, which forms the foundation of most domain-specific delta debugging approaches, by incorporating a probabilistic model. By replacing the ddmin component with ProbDD, algorithms relying on ddmin can achieve superior performance. Meanwhile, domain-specific delta debugging techniques, such as Perses, have been designed to cater to the abstract syntax tree (AST) and follow predefined sequences of attempts to minimize programs. These techniques benefit from the use of AST-based transformations, enabling them to achieve even smaller results efficiently. However, we observe that ProbDD assumes independence between elements, which may limit their performance in capturing syntactic relationships. Additionally, domain-specific approaches such as Perses rely on a predefined sequence of attempts the removal of the element and fail to utilize the information from existing test results. In this paper, we propose T-PDD, a novel approach that addresses these limitations. T-PDD leverages the AST to construct a probabilistic model, both utilizing historical test results and capturing syntactic relationships to estimate the probabilities of elements being retained in the result. It selects a set of elements that maximizes the gain for the next test based on the model and updates the model using the test results. In our evaluation, we assess our approach on 107 real-world subjects. The results demonstrate an average improvement of 26.95% in processing time and a 3.4x reduction in result size compared to Perses in the best-case scenario.