Infeasible Code Detection

A piece of code in a computer program is infeasible if it cannot be part of any normallyterminating execution of the program. We develop an algorithm for the automatic detection of all infeasible code in a program. We first translate the task of determining all infeasible code into the problem of finding all statements that can be covered by a feasible path. We prove that in order to identify all coverable statements, it is sufficient to find all coverable statements within a certain minimal subset. For this, our algorithm repeatedly queries an oracle, asking for the infeasibility of specific sets of control-flow paths. We present a sound implementation of the proposed algorithm on top of the Boogie program verifier utilizing a theorem prover to provide the oracle required by the algorithm. We show experimentally a drastic decrease in the number of theorem prover queries compared to existing approaches, resulting in an overall speedup of the entire computation. Cristiano Bertolini is a postdoctoral research fellow of the rCOS group at UNU-IIST. His research interest is in the area of user interface testing, static analysis and modeling languages. [email protected]. Martin Schäf is a postdoctoral research fellow of the rCOS group at UNU-IIST. His research interest is in the area of program verification, static analysis and runtime verification. [email protected]. Pascal Schweitzer is a CS Visiting Fellow at the Research School of Computer Science. The Australian National University. His research interest is in the area of algorithmic graph theory, geometric group theory, and graph isomorphisms. [email protected]. Copyright c © 2011 by UNU-IIST