R2M: A RECONFIGURABLE REWRITE MACHINE

Abstract

Term rewriting is a popular computational paradigm for symbolic computations such as formula manipulation, theorem proving and implementations of nonprocedural programming languages. In rewriting, the most demanding operation is repeated simplification of terms by pattern matching them against rewrite rules. We describe a parallel architecture, R2M, for accelerating this operation. R2M can operate either as a stand-alone processor using its own memory or as a backend device attached to a host using the host’s main memory. R2M uses only a fixed number (independent of input size) of processing units and fixed capacity auxiliary memory units, yet it is capable of handling variable-size rewrite rules that change during simplification. This is made possible by a simple and reconfigurable interconnection present in R2M. Finally, R2M uses a hybrid scheme that combines the ease, and efficiency of parallel pattern matching using the tree representation of terms, and the naturalness of their dag representation for replacements.