Method of developing formal identities and program bases in an

Abstract

A method operable within an optimizing compiler for generating Basis items and Kill Sets for use during subsequent global common subexpressions elimination and code motion procedures. More particularly, the method comprises assigning a symbolic register to each non-basis element to be computed as follows: creating a tuple (v) for each computation which is to be converted to a machine instruction by the compiler creating a table (optimally, a hash table) having an entry for all the tuples in the program being compiled; for every Basis element in a tuple being entered in the table a symbolic register uniquely assigned to that tuple is added to the Kill Set for that Basis element. For every non-basis element 'n' in the tuple being entered into the table, the uniquely assigned symbolic register for that tuple is added to the Kill Sets for all the Basis elements in whose Kill Sets that non-basis element 'n' appears. The symbolic register assigned to the tuple in the table is chosen to total the result of the computation of the non-basis element; and finally, a second table is constructed so that given a symbolic register, the computation which it represents can be retrieved.