Publication Date

8-2014

Date of Final Oral Examination (Defense)

5-2-2014

Type of Culminating Activity

Thesis

Degree Title

Master of Science in Computer Science

Department

Computer Science

Supervisory Committee Chair

Elena A. Sherman, Ph.D.

Supervisory Committee Member

Tim Anderson, Ph.D.

Supervisory Committee Member

Dianxiang Xu, Ph.D.

Abstract

Symbolic execution is a path sensitive program analysis technique used for error detection and test case generation. Symbolic execution tools rely on constraint solvers to determine the feasibility of program paths and generate concrete inputs for feasible paths. Therefore, the effectiveness of such tools depends on their constraint solvers.

Most modern constraint solvers for primitive data types, such as integers, are both efficient and accurate. However, the research on constraint solvers for complex data types, such as strings, is ongoing and less converged. For example, there are several types of string constraint solvers provided by researchers. However, a potential user of a string constraint solver likely has no comprehensive means to identify which solver would work best for a particular problem.

In order to help the user with selecting a solver, in addition to the commonly used performance criterion, we introduce two criteria: modeling cost and accuracy. Using these selection criteria, we evaluate four string constraint solvers in the context of symbolic execution. Our results show that, depending on the needs of the user, one solver might be more appropriate than another, yet no solver exhibits the best overall results. Hence, we suggest that the preferred approach to solving constraints for complex types is to execute all solvers in parallel and enable communication between solvers.

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