Array index allocation under register constraints in DSP programs

Code optimization for digital signal processors (DSPs) has been identified as an important new topic in system-level design of embedded systems. Both DSP processors and algorithms show special characteristics usually not found in general-purpose computing. Since real-time constraints imposed on DSP algorithms demand for very high quality machine code, high-level language compilers for DSPs should take these characteristics into account. One important characteristic of DSP algorithms is the iterative pattern of references to array elements within loops. DSPs support efficient address computations for such array accesses by means of dedicated address generation units (AGUs). In this paper, we present a heuristic code optimization technique which, given an AGU with a fixed number of address registers, minimizes the number of instructions needed for address computations in loops.