Implementing sequentially consistent programs on processor consistent platforms

This paper investigates the existence of compilers to convert programs that use shared read/write variables, with sequentially consistent memory semantics, to programs that use read/write variables with the semantics of one variant of processor consistency, known as PC-G. We first provide a simple program transformation, and prove that it compiles any 2-process program with only single-writer variables. We show that this transformation is not a general compiler for 3 or more processes; however, it does correctly transform some specific n-process programs. In particular, for the special case of the (expected) wait-free Test&Set algorithm of Tromp and Vitanyi, our transformation extends to any number of processes. Thus, one notable outcome is an implementation of Test&Set on PC-G that uses only reads and writes of shared variables. This is the first expected wait-free implementation of Test&Set on any weak memory model, and illustrates the use of randomization with a weak memory model.