Contribution to Better Handling of Irregular Problems in HPF2

In this paper, we present our contribution for handling irregular applications with HPF2 and some experimental results. We propose a programming style of irregular applications close to the regular case, so that both compile-time and run-time techniques can be more easily performed. We use the well-known tree data structure to represent irregular data structures with hierarchical access, such as sparse matrices. This algorith-mic representation avoids the indirections coming from the standard irregular programming style. We use derived data types of Fortran 90 to deene trees and some approved extensions of HPF2 for their mapping. We also propose a run-time support for irregular applications with loop-carried dependencies that cannot be determined at compile-time. Then, we present the TriDenT library, which supports distributed trees and provides run-time optimizations based on the inspector/executor paradigm. Finally, we validate our contribution with experimental results on IBM SP2 for a sparse Cholesky factorization algorithm.