Rewrite rule inference using equality saturation

Many compilers, synthesizers, and theorem provers rely on rewrite rules to simplify expressions or prove equivalences. Developing can be difficult: may subtly incorrect, profitable are easy miss, rulesets must rechecked extended whenever semantics tweaked. Large also challenging apply: redundant slow down rule-based search frustrate debugging. This paper explores how equality saturation, a promising technique that uses e-graphs apply rules, used infer rules. E-graphs compactly represent the exponentially large sets of enumerated terms potential We show saturation efficiently shrinks both sets, leading faster synthesis smaller, more general rulesets. prototyped these strategies in tool dubbed Ruler. Compared similar built CVC4, Ruler synthesizes 5.8× smaller 25× without compromising proving power. In an end-to-end case study, we Ruler-synthesized which perform as well those crafted by domain experts, addressed longstanding issue popular open source tool.