Equality saturation (EqSat) is an expression rewriting technique based on efficiently representing equivalent expressions. In recent years, it has successfully been applied in many different domains. Applying EqSat on MLIR code, however, requires additional effort for converting rewrite patterns and IR to formats that are understood by external tools. We present Tamagoyaki, an MLIR (and xDSL) framework to represent equivalences directly in your IR. Building on pdl, we apply rewrite patterns on this representation. By encoding equivalences explicitly in IR, we open the door to including more complex compiler passes in EqSat. As a case study, we replicate the core procedure of Herbie, a floating point accuracy optimizer, directly in MLIR. Additionally we show how Tamagoyaki can easily be applied to other MLIR projects such as CIRCT.

Speakers: Sasha Lopoukhine (University of Cambridge), Jules Merckx (Ghent University), Sam Coward (University College London), Jianyi Cheng (University of Edinburgh), Bjorn De Sutter (Ghent University), Tobias Grosser (University of Cambridge)