Improving Offset Assignment on Embedded Processors Using Transformations

Abstract

Embedded systems consistingof the application programROM, RAM, the embedded processor core and any custom hardware on a single wafer are becoming increasingly common in areas such as signal processing. In this paper, we address new code optimization techniques for embedded fixed point DSP processors which have limited on-chip program ROM and include indirect addressing modes usingpost increment and decrement operations. These addressingmodes allow for efficient sequential access but the addressinginstructions increase code size. Most of the previous approaches to the problem aim to find a placement or layout of variables in the memory so that it is possible to subsume explicit address pointer manipulation instructions into other instructions as a post-increment or post-decrement operation. Our solution is aimed at transformingthe access pattern by usingproperties of operators such as commutativity so that current algorithms for variable placement are more effective.