Operation Dependency Graph-Based Scheduling for High-Level Synthesis

Scheduling determines the execution order and time of operations in program. The order is related to operation dependencies, including data and resource dependencies. Data dependencies are intrinsic in programs, while resource dependencies are determined by scheduling methods. Existing scheduling methods lack an accurate and complete operation dependency graph (ODG), leading to poor performance. In this paper, we propose an ODG-based scheduling method for HLS with GNN and RL. We adopt GNN to perceive accurate relations between operations. We use the relations to guide an RL agent in building a complete ODG. We perform feedback-guided iterative scheduling with the graph to converge to a high-quality solution. Experiments show that our method reduces 23.8% and 16.4% latency on average, compared with the latest GNN-based and RL-based methods, respectively.