Method for performing common subexpression elimination on a rack-N static single assignment language

摘要

Briefly, in one embodiment, the invention is a method for eliminating common subexpressions in an initial SSA intermediate language representation of at least a portion of a computer program. The method includes (a) inserting a phi-node for an unambiguous definition used in an unambiguous subexpression reaching a join point in the initial intermediate language subsequent to the join point; (b) inserting a phi-node for the unambiguous common subexpression; (c) renaming the unambiguous definition and a subsequent use reached by the definition; and (d) renaming the unambiguous common subexpression.