For example, simplification of arithmetic expressions and propagating constants need to be combined (discovery of constants can allow further simplification, si

For example, simplification of arithmetic expressions and propagating constants need to be combined (discovery of constants can allow further simplification, simplification can reach constant results). With destructive updates you have to decide what variant has the last word (e.g. 2*a or a+a or a<<1), while an equality graph collects progress without heuristic and imprecise choices allowing equality saturation,