Towards Efficient Compiler Auto-tuning: Leveraging Synergistic Search Spaces

Determining the optimal sequence of compiler optimization passes is challenging due to the extensive and intricate search space. Traditional auto-tuning techniques, such as iterative compilation and machine learning methods, are often limited by high computational costs and difficulties in generalizing to new programs. These approaches can be inefficient and may not fully address the varying optimization needs across different programs. This paper introduces a novel approach that leverages the synergistic relationships between optimization passes to effectively reduce the search space. By focusing on chained synergy pass pairs that jointly optimize a specific target, our method uses K-means clustering to capture common optimization patterns across programs and forms these pairs into coresets. Leveraging a supervised learning model trained on these coresets, we effectively predict the most beneficial coreset for new programs, streamlining the search for optimal sequences. By integrating various search strategies, our method quickly converges to near-optimal solutions. Our approach achieves state-of-the-art performance on ten benchmark datasets, including MiBench, CBench, NPB, and CHStone, demonstrating an average reduction of 7.5% in Intermediate Representation (IR) instruction count compared to Oz. Furthermore, this set of chained synergy pass pairs is also well-suited for iterative search studies by other researchers, as it enables achieving an average codesize reduction of 13.9% compared to Oz with a simple search strategy that takes only about 5 seconds, outperforming existing search-based techniques in the initial pass search space across five datasets.