Reassociation process for code optimization

A procedure for use in an optimizing compiler termed "reassociation" determines the preferred order of combining terms in a sum so as to produce loop invariant subcomputations, or to promote common subexpressions among several essential computations, by applying the associative law of addition. To achieve this, the requisite optimization of an object program or program segment, the discrete steps of Fig. 3 must be performed after the strongly connected regions, USE and DEF chains have all been identified.