Optimizing DSP scheduling via address assignment with array and loop transformation

Reducing address arithmetic instructions by optimization of address offset assignment greatly improves the performance of DSP applications. However, minimizing address operations alone may not directly reduce code size and schedule length for multiple functional units DSPs. In this paper, we exploit address assignment and scheduling for application with loops on multiple functional unit DSPs. Array transformation is used in our approach to leverage the indirect addressing modes provided by most of the DSP architectures. An algorithm, address instruction reduction loop scheduling (AIRLS), is proposed. The algorithm utilizes the techniques of rotation scheduling, address assignment and array transformation to minimize both address instructions and schedule length. Compared to the list scheduling, AIRLS shows an average reduction of 35.4% in schedule length and an average reduction of 38.3% in address instructions. Compared to the rotation scheduling, AIRLS shows an average reduction of 19.2% in schedule length and 39.5% in the number of address instructions.