Method and apparatus for predicting and scheduling copy instruction for software pipelined loops

Abstract

A method for scheduling instructions for execution on a computer system includes scanning a plurality of loop instructions that are modulo scheduled to identify a first instruction and a second instruction that both utilize a register of the computer system upon execution of the plurality of instructions. The loop has a first initiation interval. The first instruction defines a first value of the register in a first iteration of the loop and the second instruction redefines the value of the register to a second value in a subsequent iteration of the loop prior to a use of the first value in the first iteration of the loop. A copy instruction is inserted in the loop instructions to copy the first value prior to execution of the second instruction. A schedule is determined after the insertion of the one or more copy instructions giving a second initiation interval.