Pushdown Control-Flow Analysis of Higher-Order Programs

Context-free approaches to static analysis gain precision over classical approaches by perfectly matching returns to call sites— a property that eliminates spurious interprocedural paths. Vardoulakis and Shivers’s recent formulation of CFA2 showed that it is possible (if expensive) to apply context-free methods to higherorder languages and gain the same boost in precision achieved over first-order programs. To this young body of work on context-free analysis of higherorder programs, we contribute a pushdown control-flow analysis framework, which we derive as an abstract interpretation of a CESK machine with an unbounded stack. One instantiation of this framework marks the first polyvariant pushdown analysis of higherorder programs; another marks the first polynomial-time analysis. In the end, we arrive at a framework for control-flow analysis that can efficiently compute pushdown generalizations of classical control-flow analyses.