High Performance Fortran: History, Status and Future

High Performance Fortran (HPF) is a data-parallel language that was designed to provide the user with a high-level interface for programming scientific applications, while delegating to the compiler the task of generating an explicitly parallel message-passing program. The main objective of this paper is to study the expressivity of the language and related performance issues. After giving an outline of developments that led to HPF and shortly explaining its major features, we discuss in detail a variety of approaches for solving multiblock problems and applications dealing with unstructured meshes. We argue that the efficient solution of these problems does not only need the full range of the HPF Approved Extensions, but also requires additional features such as the explicit control of communication schedules and support for value-based alignment. The final part of the paper points out some classes of problems that are difficult to deal with efficiently within the HPF paradigm