GATHERING SYSTEM FOR SUBSCRIPT INFORMATION OF LOOP

摘要

PURPOSE: To obtain the subscript information gathering system which extracts the initial value, end value, and increment of a loop variance and gathers them as the subscript information of the loop by determining the loop variance according to a for statement at the time of optimization. ;CONSTITUTION: A syntax analysis part 3 analyzes the syntax of a source program which has no loop variance in its grammar to generate a syntax tree. A loop structure conversion part 6 converts the loop structure into loop structure which uses the frequency of looping. A subscript information gathering part 7 extracts the initial value, end value, and increment of the loop variable from the for statement in the loop structure respectively and gathers them as the subscript information of the loop. Further, a loop structure conversion part 6 retrieves the extracted variable in the loop to remove defined (altered) variables, and then determines a variable whose initial value, end value, and increment are already determined as a loop variable. Thus, the loop variable is determined at the time of the optimization according to the for statement and the initial value, end value, and increment of the loop variable can be extracted and employed as the subscript information of the loop.;COPYRIGHT: (C)1993,JPO&Japio