Finding fix locations for cfl-reachability analyses via minimum cuts

Abstract

Static analysis tools are increasingly important for ensuring code quality. Ideally, all warnings from a static analysis would be addressed, but the volume of warnings and false positives usually makes this effort prohibitive. We present techniques for finding fix locations, a small set of program locations where fixes can be applied to address all static analysis warnings. We focus on analyses expressible as context-free-language reachability, where a set of fix locations is naturally expressed as a min-cut of the CFL graph. We show, surprisingly, that computing such a CFL min-cut is NP-hard. We then phrase the problem of finding CFL min-cuts as an optimization problem which allows us to trade-off the size of the cut vs. the preservation of computed information. We then show how to solve the optimization problem via a MaxSAT encoding. Our evaluation shows that we compute fix location sets that are significantly smaller than both the number of warnings and, in the case of a true CFL min-cut, the fix location sets from a normal min-cut.