STORAGE ASSIGNMENT TO DECREASE CODE SIZE

DSP architectures typically provide indirect addressing modes with aut oincrement and decrement. In addition, indexing mode is generally not available, and there are usually few, if any, general-purpose register s. Hence, it is necessary to use address registers and perform address arithmetic to access automatic variables. Subsuming the address arith metic into autoincrement and decrement modes improves the size of the generated code. In this article we present a formulation of the proble m of optimal storage assignment such that explicit instructions for ad dress arithmetic are minimized. We prove that for the case of a single address register the decision problem is NP-complete, even for a sing le basic block. We then generalize the problem to multiple address reg isters. For both cases heuristic algorithms are given, and experimenta l results are presented.