Abstract

The design of consistency models for both hardware and software is a difficult task. For programming languages it is particularly difficult because the target audience for a programming language is much wider than the target audience for a hardware programming language, making usability a more important criteria. Exacerbating this problem is the reality that the programming languages community has little experience designing programming language consistency models, and therefore each new attempt is very much a voyage into uncharted territory. A concrete example of the difficulties of the task is the current Java Memory Model. Although designed to be easy to use by Java programmers, it is poorly understood and at least one common idiom (the "double check idiom") to exploit the model is unsafe. In this paper we describe the design of an optimizing Java compiler that will allow a consistency model for the code to be compiled to be specified as an input. The compiler will use Shasha and Snir's delay set analysis, and our CSSA program representation, to normalize the effects of different consistency models on optimizations and analysis. When completed, the compiler will serve as a testbed to prototype new memory models, and to measure the differences of different memory models on program performance.

Citations