STORAGE ASSIGNMENT TO DECREASE CODE SIZE

DSP architectures typically provide indirect addressing modes with aut o-increment and decrement. In addition, indexing mode is not available , and there are usually few, if any, general-purpose registers. Hence, it is necessary to use address registers and perform address arithmet ic to access automatic variables. Subsuming the address arithmetic int o auto-increment and auto-decrement modes improves the size of the gen erated code. In this paper we present a formulation of the problem of optimal storage assignment such that explicit instructions for address arithmetic are minimized. We prove that for the case of a single addr ess register the decision problem is NP-complete. We then generalize t he problem to multiple address registers. For both cases heuristic alg orithms are given. Our experimental results indicate an improvement of 3.