PROMOTER : A High - Level , Object - ParallelProgramming Language

The superior performance and cost-eeectiveness of scalable, distributed memory parallel computers will only then become generally exploitable if the programming diiculties with such machines are overcome. We see the ultimate solution in high-level programming models and appropriate parallelizing compilers that allow the user to formulate a parallel program in terms of application-speciic concepts, while low-level issues such as optimal data distribution and coordination of the parallel threads are handled by the compiler. High Performance Fortran (HPF) is a major step in that direction; however, HPF still lacks in the generality of computing domains needed to treat other than regular, data-parallel numerical applications. A more exible and more abstract programming language for regular and irregular object-parallel applications is PROMOTER. PROMOTER allows the user to program for an application-oriented abstract machine rather than for particular architecture. The wide semantic gap between the abstract machine and the concrete message-passing architecture is closed by the compiler. Hence, the issues of data distribution, communication, and coordination (thread scheduling) are hidden from the user. The paper presents the underlying concepts of PROMOTER and the corresponding language concepts. The PROMOTER compiler translates the parallel program written in terms of distributed types into parallel threads and maps those optimally onto the nodes of the physical machine. The language constructs and their use, the tasks of the compiler, and the challenges encountered in its implementation are discussed.