Expressing Irregular Computations in Modern Fortran Dialects

Modern dialects of Fortran enjoy wide use and good support on highperformance computers as performance-oriented programming languages. By providing the ability to express nested data parallelism in Fortran, we enable irregular computations to be incorporated into existing applications with minimal rewriting and without sacrificing performance within the regular portions of the application. Since performance of nested data-parallel computation is unpredictable and often poor using current compilers, we investigate source-to-source transformation techniques that yield Fortran 90 programs with improved performance and performance stability.