Automatic Program Repair (APR) techniques have shown the potential of reducing debugging costs while improving software quality by generating patches for fixing bugs automatically. However, they often generate many overfitting patches which pass only a specific test-suite but do not fix the bugs correctly. This paper proposes MIPI, a novel approach to reducing the number of overfitting patches generated in the APR. We leverage recent advances in deep learning to exploit the similarity between the patched method’s name (which often encloses the developer’s intention about the code) and the semantic meaning of the method’s body (which represents the actual implemented behavior) for identifying and removing overfitting patches generated by APR tools. Experiments with a large dataset of patches for QuixBugs and Defects4J programs show the promise of our approach. Specifically, in a total of 1,191 patches generated by 23 existing APR tools, MIPI successfully filters out 254 (32%) of the total 797 overfitting patches with a precision of 90% while preserving 93% of the correct patches. MIPI is more precise and less damaging to the APR than existing heuristic patch assessment techniques, achieving a higher recall than automated testing-based techniques that do not have access to the test oracle. In addition, MIPI is highly complementary to existing automated patch assessment techniques.

Recently, Automatic Program Repair (APR) has shown a high capability of repairing software bugs automatically. In general, most of the APR techniques require test suites to validate automatically generated patches. However, the test suites used for patch validation might contain thousands of test cases. Running these whole test suites to validate every program variant makes the validation process not only time-consuming but also expensive. To mitigate this issue and to enhance the patch validation in APR, we introduce (1) MPTPS (Modification Point-aware Test Prioritization and Sampling), which iteratively records test execution. Based on the failed test information, it performs test prioritization, then sampling to reduce the test execution time by moving forward the test cases that are most likely to fail in the test suite; and (2) a new fitness function that refines the existing one to improve repair efficiency. We implemented our MPPEngine approach in the Astor workspace by extending jGenProg. And the experiments on the Defects4j benchmark against jGenProg show that, on average, jGenProg consumes 79.27 s to validate one program variant, where MPPEngine takes only 33.70 s for results in 57.50% of validation time reduction. Also, MPPEngine outperforms jGenProg by finding patches for six more bugs than jGenProg.

Automatically fixing bugs in software programs can significantly reduce the cost and improve the productivity of the software. Toward this goal, a critical and challenging problem is automatic fix localization, which identifies program locations where a bug fix can be synthesized. In this paper, we present AgxFaults, a technique that automatically identifies minimal subsets of program statements at which a suitable modification can remove the error. AgxFaults works based on dynamically encoding semantic of program parts that are relevant to an observed error into an unsatisfiable logical formula and then manipulating this formula in an increasingly on-demand manner. We perform various experiments on faulty versions of the traffic collision avoidance system (TCAS) program in the Siemens Suite, programs in Bekkouche’s benchmark, and server real bugs in the Defects4J benchmark. The experimental results show that AgxFaults outperforms single-path-formula approaches in terms of effectiveness in finding fix localization and fault localization. AgxFaults is better than program-formula-based approaches in terms of efficiency and scalability, while providing similar effectiveness. Specifically, the solving time of AgxFaults is 28% faster, and the running time is 45% faster, than the program-formula-based approach, while providing similar fault localization results.