Abstract: A compiler apparatus in a computer converts source program to object program to be executed by the computer. If loop instructions are included in the object program, the resource reference extraction section extracts resources referred by the loop instructions and the resource change extraction section extracts resources changed by the loop instructions. The loop parallel decision section decides possibility of parallel execution for different stages of the loop instructions according to the extraction result.

Abstract: In loop processing by an electronic computer that simultaneously executes a plurality of instructions, a loop optimization system according to this invention comprises loop analyzing means for judging whether or not the process of expanding iterations of instructions in a loop into one iteration is performed based on at least one of the number of operations in each iteration in the loop and the number of memory access instruction; loop expanding means for converting a given number of iterations in an instruction sequence of the loop into an equivalent instruction sequence where those iterations are expanded into one iteration; and loop optimizing means for rearranging instructions in the developed loop so that different repetitious operations may be allocated to separate processing units for simultaneous execution.