Distributed memory architectures have become popular as a viable and cost-effective method of building scalable parallel computers. However, the absence of global address space, and consequently, the need for explicit message passing among processes makes these machines very difficult to program. This has motivated the design of languages like High Performance Fortran [14], which allow the programmer to write sequential or shared-memory parallel programs that are annotated with directives specifying data decomposition. The compilers for these languages are responsible for partitioning the computation, and generating the communication necessary to fetch values of nonlocal data referenced by a processor. A number of such prototype compilers have been developed [3, 6, 19, 23, 29, 30, 33, 34, 43].