High-level Synthesis Directives Design Optimization via Large Language Model

Xufeng Yao, Wenqian Zhao, Qi Long Sun, Cheng Zhuo, Bei Yu · ACM Transactions on Design Automation of Electronic Systems · 2025

High-level synthesis is an effective methodology that accelerates early-stage circuit design. The optimization of HLS directives has been a critical yet challenging endeavor, with prevailing research primarily concentrating on custom feature engineering and dedicated model designs. However, these conventional approaches often fall short of fully harnessing the intricate latent information embedded within raw HLS directives, potentially limiting the scope and efficiency of optimization processes. In response to these challenges, this article pioneers the integration of large language model (LLM) into the HLS optimization workflow, leveraging their capabilities as both sophisticated feature extractors and autonomous agents. This application of LLM marks a significant departure from traditional methods, introducing a more nuanced and effective strategy for navigating the complex landscape of HLS directive optimization, enabling a more efficient exploration of the design space and prioritization of search strategies. Specifically, our approach makes a significant improvement to the Pareto frontier in directive design, enabling a more rapid and efficient design space exploration. This demonstrates not only an increase in optimization performance but also a decrease in computational overhead, thereby promising significant time savings in the circuit design process. This work not only enhances the current state of HLS directive optimization but also makes new avenues for the application of language models in the field of EDA. Our work makes the following key achievements: We propose an LLM-based framework for effective HLS directives design space exploration; We utilize the prior knowledge of LLM and fine-tune an LLM for HLS directives optimization; Empirical results demonstrate this LLM-based approach’s effectiveness. Specifically, we obtain 15% improvement on the normalized ADRS metric, demonstrating superior performance with limited sampling steps compared with current leading algorithms.

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