Bitwidth-aware scheduling and binding in high-level synthesis

Many high-level description languages, such as C/C++ or Java, lack the capability to specify the bitwidth information for variables and operations. Synthesis from these specifications without bitwidth analysis may introduce wasted resources. Furthermore, conventional high-level synthesis techniques usually focus on uniform-width resources, thus they cannot obtain the full resource savings even with bitwidth information. This work develops a bitwidth-aware synthesis flow, including bitwidth analysis, scheduling and binding, and register allocation and binding, to exploit the multi-bitwidth nature of operations and variables for area-efficient designs. We also develop lower bound estimation to evaluate the efficiency of our proposed solutions for register allocation and binding. The flow is implemented in the MCAS synthesis system (Cong et al., 2004). Experimental results show that our proposed bitwidth-aware synthesis flow reduces area by 36% and wire-length by 52% on average compared to the uniform-width MCAS flow, while achieving the same performance.