Fast Optimal Instruction Scheduling for Single-Issue Processors with Arbitrary Latencies

Instruction scheduling is one of the most important steps for improving the performance of object code produced by a compiler. The local instruction scheduling problem is to nd a minimum length instruction schedule for a basic block subject to precedence, latency, and resource constraints. In this paper we consider local instruction scheduling for single-issue processors with arbitrary latencies. The problem is considered intractable, and heuristic approaches are currently used in production compilers. In contrast, we present a relatively simple approach to instruction scheduling based on constraint programming which is fast and optimal. The proposed approach uses an improved constraint model which allows it to scale up to very large, real problems. We describe powerful redundant constraints that allow a standard constraint solver to solve these scheduling problems in an almost backtrack-free manner. The redundant constraints are lower bounds on selected sub-problems which take advanta...

• Type: Conference
• Year: 2001
• Where: CP
• Authors: Peter van Beek, Kent D. Wilken
• Keywords: Artificial Intelligence, CP 2001, Instruction Scheduling, Local Instruction Scheduling, Scheduling Problems