SynaSpace: Behavior-Driven Configuration Optimization of Test Generators for Logic Synthesis Testing

As FPGA design complexity increases, the correctness and reliability of logic synthesis tools are critical to ensuring correct hardware implementation. These tools translate hardware description languages (e.g., Verilog) into gate-level netlists, where latent faults may introduce functional errors or performance degradation during synthesis. Existing approaches rely on automatically generated Verilog test cases to find these latent faults. However, their effectiveness depends heavily on generator configurations and is typically guided by input diversity, which fails to accurately capture differences in synthesis behavior. Moreover, the high-dimensional configuration space of generator further hinders efficient exploration. To address these challenges, we propose SynaSpace, a behavior-driven configuration optimization framework for fault detection in logic synthesis tools. SynaSpace focuses on synthesis behavior coverage to guide configuration search, by constructing behavioral representations through joint analysis of synthesis logs and gate-level netlists. The framework comprises four components: (1) configuration space modeling for unified parameter representation; (2) Bayesian optimization–based configuration search for efficient exploration; (3) synthesis behavior characterization and coverage evaluation for capturing and quantifying behavioral differences; and (4) fault detection and utility modeling for extracting effective feedback via differential testing and deduplication. These components are integrated into a unified optimization framework to enable efficient configuration exploration and improved testing effectiveness. We evaluate SynaSpace on two established logic synthesis tools (i.e., Vivado and Yosys). SynaSpace identifies 18 faults across four categories, all of which have been confirmed and fixed by vendors and the open-source community.