Code compression by register operand dependency

Abstract

This paper proposes a dictionary-based code compression technique that maps the source register operands to the nearest occurrence of a destination register in the predecessor instructions. The key idea is that most destination registers have a great possibility to be used as source registers in the following instructions. The dependent registers can be removed from the dictionary if this information can be specified otherwise. As a result, the compression ratio benefits from the decreased dictionary size. A set of programs has been compressed using this feature. The compression results show that the average compression ratio is reduced to 38.6% on average for MediaBench benchmarks compiled for MIPS R2000 processor.