Extending List Scheduling to Consider Execution Frequency

Frequency-Based List Scheduling (FBLS) extends standard List Scheduling by considering execution frequencies within a schedule. This is useful for global instruction scheduling methods that schedule groups of basic blocks, called meta-blocks, as though they were a single block. Traditional local schedulers operate on the premise that each instruction is executed the same number of times as every other instruction in the “block”, an unwarrented assumption for meta-blocks. This assumption can lead metablocks schedulers to produce inefficient code. FBLS provides an answer to this problem by considering the differing execution frequencies within meta-blocks when scheduling operations. To evaluate our contention that FBLS is a useful extension to standard list scheduling, we implemented FBLS and compared it to standard list scheduling within the context of dominator-path scheduling [1], a meta-block global scheduling algorithm. Experimental results show overall run-time improvement of 10.9% for livermore loops.