Improving Virtual Prototype Driven Hardware Optimization by Merging Instruction Sequences

Tailoring hardware to an application significantly enhances its performance compared to using a general-purpose processor. While hardware optimization is essential to meet the user requirements for resource-constrained embedded systems, it generally entails considerable costs and a high level of effort. In recent work virtual prototypes have been shown to be an effective analysis tool for guiding this process. In best-case scenarios, it is possible to identify a single recurring instruction sequence that covers approximately 55 % of all executed instructions and is thus suitable for optimization by a Hardware Accelerator (HA). However, challenges arise for applications where each identified sequence only covers a small fraction of the total execution. In order to achieve comparable coverage, several HAs can be designed, but this also multiplies the hardware costs. To address these issues, this work proposes an approach to extend and merge identified sequences allowing the design of a single HA for the merged sequence. Experiments show that this approach significantly increases the coverage achievable with a single HA while the resulting performance loss is negligible compared to building multiple HAs.