METHOD AND APPARATUS FOR EFFICIENT DETERMINATION OF AN RMII VECTOR FOR MODULO SCHEDULED LOOPS IN AN OPTIMIZING COMPILER

Apparatus and methods are disclosed for determining a recurrence minimum iteration interval (rmii) vector for use in modulo scheduling target program instructions during the code optimization pass of an optimizing compiler. Most modem microprocessors have the ability to issue multiple instructions in one clock cycle and/or possess multiple pipelined functional units. They also have the ability to add two values to form the address within memory load and store instructions. For such microprocessors this invention can, where applicable, accelerate the process of modulo-scheduling target program loops. The invention consists of a technique to determine a rmii vector, which is a set of rmii values which correspond to different values of instruction load latency. The disclosed invention makes the determination of the entire vector with only minimal effort over determining a single rmii value.