A novel approach for detecting heap-based loop-carried dependences

The problem of data dependences in pointer-based codes is crucial to various compiler optimizations. The approach presented in this paper focus on detecting data dependences induced by heap-directed pointers on loops that access dynamic data structures. Knowledge about the shape of the data structure accessible from a heap-directed pointer provides critical information for disambiguating heap accesses originating from it. Our approach is based on a previously developed shape analysis that maintains topological information of the connections among the different nodes (memory locations) in the data structure. As a novelty, our approach carries out abstract interpretation of the statements being analyzed, annotating memory locations with read/write information. This information will be later used in a very accurate dependence test, which we describe in this paper. We also discuss its application to three different programs: the sparse matrix-vector product, mst from Olden and twolf from the SPEC CPU2000 suite.