Efficient instruction scheduling for a pipelined architecture

Phillip B. Gibbons, Steven S. Muchnick

Abstract: As part of an effort to develop an optimizing compiler for a pipelined architecture, a code reorganization algorithm has been developed that significantly reduces the number of runtime pipeline interlocks. In a pass after code generation, the algorithm uses a dag representation to heuristically schedule the instructions in each basic block. Previous algorithms for reducing pipeline interlocks have had worst-case runtimes of at least O (n4). By using a dag representation which prevents scheduling deadlocks and a selection method that requires no lookahead, the resulting algorithm reorganizes instructions almost as effectively in practice, while having an O (n2) worst-case runtime.