COMPILATION TECHNIQUE FOR SOFTWARE PIPELINING OF LOOPS WITH CONDITIONAL JUMPS.

Abstract

The author describes a compilation algorithm for efficient software pipelining of general inner loops, where the number of iterations and the time taken by each iteration may be unpredictable, due to aribtrary IF-THEN-ELSE statements and conditional exit statements within the loop. As the target machine, the author assumes a wide-instruction-word architecture that allows multiway branching in the form of IF-THEN-ELSE trees, and that allows conditional register transfers depending on how the microinstruction branches. The compilation algorithm, called the pipeline scheduling technique, produces a software-pipelined version of a given inner loop, which allows a new iteration of the loop to begin on every cycle, whenever dependences and resources permit. The correctness and termination properties of the algorithm are studied.