This paper sets out to reveal the relationship between code pattern and infeasible paths and gives advices to the selection of infeasible path detection techniques. Lots of program paths are proved to be infeasible, which leads to imprecision and low efficiency of program analysis. Detection of infeasible paths is required in many areas of software engineering including test coverage analysis, test case generation, and security vulnerability analysis. The immediate cause of path infeasibility is the contradiction of path constraints, whose distribution will affect the performance of different program analysis techniques. But there is a lack of research on the distribution of contradict constraints currently. We propose a code pattern based on the empirical study of infeasible paths; the statistical result proves the correlation of the pattern with contradict constraints. We then develop a path feasibility detection method based on backward symbolic execution. Performance of the proposed technique is evaluated from two aspects: the efficiency of detecting infeasibility paths for specific program element and the improvement of applying the technique on code coverage testing.
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