Automated program verification made SYMPLAR: symbolic permissions for lightweight automated reasoning

Abstract

Research in automated program verification against specifications written in first-order logic has come a long way. Ever-faster Satisfiability Modulo Theories (SMT) solvers [Barrett et al. 2010] promise to verify program instructions quickly against specifications. Unfortunately, aliasing still prevents automated program verification tools from easily and soundly verifying interesting programs. This paper introduces the use of symbolic permissions as the basis for sound automated program verification. Symbolic permissions provide a simple alias control mechanism with expressiveness similar to the well-known fractional permissions [Boyland 2003]. The paper shows that symbolic permissions can be enforced with a linear refinement typechecking procedure. Once permissions are checked, aliasing can essentially be ignored for the purposes of program verification, which allows taking full advantage of SMT solvers for doing the heavy verification lifting. The paper shows that a verification tool based on symbolic permissions can easily verify a design pattern with inherent aliasing challenges.