Array Data Flow Analysis for Load-Store Optimizations in Fine-Grain Architectures

The performence of scientific programs on modern processors can be significantly degraded by memory references that frequently arise due to load and store operations associated with array references. We have developed techniques for optimally allocating registers to array elements whose values are repeatedly referenced over one or more loop iterations. The resulting placement of loads and stores is optimal in that number of loads and stores encoutered along each path through the loop is minimal for the given program branching structure. To place load, store, and register-to-register shift operations without introducing fully/partially redundant and dead memory operations, a detailed value flow analysis of array references is required. We present an analysis framework to efficiently solve various data flow problems required by array load-store optimizations. The framework determines the collective behavior of recurrent references spread over multiple loop iterations. We also demonstrate how our algorithms can be adapted for various fine-grain architectures.