Redundant synchronization elimination for DOACROSS loops

Synchronizations are necessary when there are dependences between concurrent processes. However, many synchronizations are redundant because the composite effect of the other synchronizations may have already covered them. In this paper, we investigate the problem of redundant synchronization elimination in DOACROSS loops and present an algorithm that identifies redundant synchronizations in doubly-nested DOACROSS loops with multiple statements. Nonuniformity in redundancy at the boundaries of the loop iteration space, which is caused primarily by the backward dependence directions in some inner loops, is addressed. These results allow a compiler to generate efficient data synchronization instructions for DOACROSS loops