Compositionality Entails Sequentializability

We show that any concurrent program that is amenable to compositional reasoning can be effectively translated to a sequential program. More precisely, we give a reduction from the verification problem for concurrent programs against safety specifications to the verification of sequential programs against safety specifications, where the reduction is parameterized by a set of auxiliary variables A, such that the concurrent program compositionally satisfies its specification using auxiliary variables A iff the sequentialization satisfies its specification. Existing sequentializations for concurrent programs work only for underapproximations like bounded context-switching, while our sequentialization has the salient feature that it can prove concurrent programs entirely correct, as long as it has a compositional proof. The sequentialization allows us to use sequential verification tools (including deductive verification tools and predicate abstraction tools) to analyze and prove concurrent programs correct. We also report on our experience in the deductive verification of concurrent programs by proving their sequential counterparts using the program verifier Boogie.