Decreasing process memory requirements by overlapping program portions

Most compiler optimizations focus on saving time and sometimes occur at the expense of increasing size. Yet processor speeds continue to increase at a faster rate than main memory and disk access times. Processors are now frequently being used in embedded systems that often have strict limitations on the size of programs it can execute. Also, reducing the size of a program may result in improved memory hierarchy performance. This paper describes general techniques for decreasing the memory requirements for a process by automatically overlapping portions of a program. Live range analysis, similar to the analysis used for allocating variables to registers, is used to determine which program portions conflict. Nonconflicting portions are assigned overlapping memory locations. The results show an average decrease of over 10% in process size for a variety of programs with minimal or no dynamic instruction increases