1. A method of compiling a source program including a loop into an object program enabling iterations of the loop to be executed in parallel by a plurality of parallel processes in a multiprocessor system, the method including steps to be executed by a computer system, the steps including: analyzing the source program and translating the source program into intermediate codes, based upon a result of the analyzing; converting a portion within the intermediate codes corresponding to the loop of the source program into a parallel process portion to be executed by the plurality of parallel processes as respective parts of the iterations to be processed by the loop, wherein a particular variable, if the particular variable exists, which is included in the loop and having a value defined within the loop, is converted at the converting step into a local variable which is valid during the execution of the parallel process portion by one of the plurality of parallel processes and is not shared by the plurality of parallel processes; and generating from the intermediate codes obtained after the converting step, an object program executable by the plurality of parallel processes in the multiprocessor system; when the particular variable exists in the loop, the converting step further including: detecting whether a value of the particular variable is defined at any of the iterations of the loop; and adding final value guaranteeing codes to the parallel process portion as part thereof, if a result of the detecting is affirmative, the adding including: detecting during execution of the parallel process portion by the plurality of parallel processes whether a one process of the plurality of parallel processes executes a last iteration of the loop and adding a first code identifying the one process; and adding a second code representing a final value of the local variable representing the particular variable, obtained by execution of the parallel process portion by the plurality of parallel processes, the second code being set into a value of the particular variable to be used after execution by the plurality of parallel processes, the setting being executed when the one process identified by the first code is detected at execution thereof to be the one process which executes the last iteration in the loop.