Titan: Enabling large and complex benchmarks in academic CAD

Benchmarks play a key role in FPGA architecture and CAD research, enabling the quantitative comparison of tools and architectures. It is important that these benchmarks reflect modern designs which are large scale systems that make use of heterogeneous resources; however, most current FPGA benchmarks are both small and simple. In this paper we present Titan, a hybrid CAD flow that addresses these issues. The flow uses Altera's Quartus II FPGA CAD software to perform HDL synthesis and a conversion tool to translate the result into the academic BLIF format. Using this flow we created the Titan23 benchmark set, which consists of 23 large (90K-1.8M block) benchmark circuits covering a wide range of application domains. Using the Titan23 benchmarks and a detailed model of Altera's Stratix IV architecture we compared the performance and quality of VPR and Quartus II targeting the same architecture. We found that VPR is at least 2.7× slower, uses 5.1× more memory and 2.6× more wire compared to Quartus II. Finally, we identified that VPR's focus on achieving a dense packing is responsible for a large portion of the wire length gap.