High-Level Synthesis of Loops Using the Polyhedral Model

High-level synthesis (HLS) of loops allows efficient handling of intensive computations of an application, e.g. in signal processing. Unrolling loops, the classical technique used in most HLS tools, cannot produce regular parallel architectures which are often needed. In this Chapter, we present, through the example of the MMAlpha testbed, basic techniques which are at the heart of loop analysis and parallelization. We present here the point of view of the polyhedral model of loops, where iterative calculations are represented as recurrence equations on integral polyhedra. Illustrated from an example of string alignment, we describe the various transformations allowing HLS and we explain how these transformation can be merged in a synthesis flow