TRACO: Source-to-Source Parallelizing Compiler

The paper presents a source-to-source compiler, TRACO, for automatic extraction of both coarse- and fine-grained parallelism available in C/C++ loops. Parallelization techniques implemented in TRACO are based on the transitive closure of a relation describing all the dependences in a loop. Coarse- and fine-grained parallelism is represented with synchronization-free slices (space partitions) and a legal loop statement instance schedule (time partitions), respectively. TRACO enables also applying scalar and array variable privatization as well as parallel reduction. On its output, TRACO produces compilable parallel OpenMP C/C++ and/or OpenACC C/C++ code. The effectiveness of TRACO, efficiency of parallel code produced by TRACO, and the time of parallel code production are evaluated by means of the NAS Parallel Benchmark and Polyhedral Benchmark suites. These features of TRACO are compared with closely related compilers such as ICC, Pluto, Par4All, and Cetus. Feature work is outlined

Computing the transitive closure of a union of affine integer tuple relations

International audienceThis paper proposes a method to compute the transitive clo- sure of a union of a±ne relations on integer tuples. Within Presburger arithmetics, complete algorithms to compute the transitive closure exist for convex polyhedra only. In presence of non-convex relations, there ex- ist little but special cases and incomplete heuristics. We introduce a novel su±cient and necessary condition de¯ning a class of relations for which an exact computation is possible. Our method is immediately applica- ble to a wide area of symbolic computation problems. It is illustrated on representative examples and compared with state-of-the-art approaches