← Monday, October 5, 2026Performance & OSDeep dive

Refinement e-graphs model compiler rewrites that narrow program behavior

philipzucker.com 34 min read Editor score 7/10

The proposal adds a privileged refinement relation alongside equality in e-graphs, for rewrites that make underspecified programs more concrete; a prototype is available. Compiler engineers can use this framing to reason about optimizations when language semantics leave behavior open.

What

Refinement e-graphs add an inequality relation to e-graphs for representing compiler rewrites that narrow program behavior.

How

A refinement rewrite can move from an abstract program to a more determined one; in the don’t-care circuit example, an unspecified result can refine to true or false.

Why it matters

Representing refinement separately from equality lets an optimizer exploit unspecified behavior without equating distinct possible results.

Read on philipzucker.com → Lobsters

Headline, summary, brief and diagram are written by a model from the source's own text; the link, byline and numbers come from the source. Read the original before relying on a claim.