Code-Size Conscious Pipelining of Imperfectly Nested Loops

International audienceThis paper is a step towards enabling multidimensional software pipelining of non-perfectly nested loops on memory-constrained architectures.We propose a method to pipeline multiple inner loops without increasing the size of the loop nest, apart from an outermost prolog and epilog. We focus on the domain of media and signal processing, where short inner loops are common and where embedded constraints drive the selection of code-size conscious algorithms. Our first results indicate that the additional constraints associated with the method do not impede the extraction of significant amounts of instruction-level parallelism. In addition to preserving precious scratch-pad or cache memory, our method also avoids the performance overhead of prologs and epilogs resulting from pipelined inner loops with short trip count