How many addressing modes are enough?

Abstract

Programs naturally require a variety of memory-addressing modes. It isn't necessary to provide them in hardware, however, if a compiler can synthesize them from a few primitive modes. This not only simplifies the hardware, but also permits the compiler to use its understanding of the program to economize on the modes which it uses. We present some compilation techniques that allow the compiler to deal effectively with a single addressing mode in a target RISC processor. We also give measurements to show the benefits of such techniques, and to support our assertion that a single addressing mode is adequate for a general purpose processor, provided that mode incorporates both a pointer and an offset.