Moirae: Generating High-Performance Composite Stencil Programs with Global Optimizations

Stencil computation is one of the most universal computation motifs in scientific applications such as weather prediction. Due to the complexity of scientific simulation, the stencil computation can contain a set of complex stencil operations that form a directed acyclic graph (referred to composite stencil). Unfortunately, most existing stencil optimizations and compilers only focus on intra-stencil operation, and cannot fully explore the performance improvement potential of composite stencils in nowadays applications. To this end, we propose Moirae, a framework that explores a novel optimization space and generates high-performance code for composite stencils. We first propose a lightweight cost model with a fine-grained analysis of memory access behavior to predict the performance. Based on the cost model, we propose an evolutionary search method to find a high-performance optimization, leveraging a search space pruning method with stencil domain knowledge. Experimental results show that Moirae can outperform the state-of-the-art composite stencil compilers.