Equality saturation: a new approach to optimization

Optimizations in a traditional compiler are applied sequentially, with each optimization destructively modifying the program to produce a transformed program that is then passed to the next optimization. We present a new approach for structuring the optimization phase of a compiler. In our approach, optimizations take the form of equality analyses that add equality information to a common intermediate representation. The optimizer works by repeatedly applying these analyses to infer equivalences between program fragments, thus saturating the intermediate representation with equalities. Once saturated, the intermediate representation encodes multiple optimized versions of the input program. At this point, a profitability heuristic picks the final optimized program from the various programs represented in the saturated representation. Our proposed way of structuring optimizers has a variety of benefits over previous approaches: our approach obviates the need to worry about optimization ...

• Type: Conference
• Year: 2009
• Where: POPL
• Authors: Ross Tate, Michael Stepp, Zachary Tatlock, Sorin Lerner
• Keywords: Common Intermediate Representation, Intermediate Representation, Keywords Compiler Optimization, POPL 2009, Programming Languages