Cross-loop Reuse Analysis and its Application to Cache Optimizations

. In this paper we describe the design of a data-flow framework for detecting cross-loop reuse. Cross-loop reuse takes place when a set of data items or cache lines is accessed in a given loop nest and then accessed again within some subsequent portion of the program, usually another outer loop nest. In contrast to intra-loop reuse, which occurs during the execution of a single loop nest, cross-loop reuse is hard to analyze using traditional dependence-based techniques. The framework we have constructed is based on a combination of array section analysis (to capture array access patterns at a high level) and data-flow analysis (to deal with intra-procedural control flow). The framework is designed to account for cache size when gathering reuse information, and when used in an interprocedural setting, the framework also provides a mechanism for summarizing the effects of procedure calls. Cross-loop reuse information can be used to drive a number of transformations that enhance locality ..