high performance computing on graphics processing units: hgpu.org

High-level synthesis (HLS) has gained considerable traction over the recent years as it allows for faster development and verification of hardware accelerators than traditional RTL design. While HLS allows for most bugs to be caught during software verification, certain non-deterministic or data-dependent bugs still require debugging the actual hardware system during execution. Recent work has focused on techniques to allow designers to perform in-system debug of HLS circuits in the context of the original software code; however, like RTL debug, the user must still determine the root-cause of a bug using small execution traces, with lengthy debug turns. In this work we demonstrate techniques aimed at reducing the time HLS designers spend performing in-system debug. Our approaches consist of performing data dependency analysis in order to guide the user in selecting which variables are observed by the debug instrumentation, as well as an associated debug overlay that allows for rapid reconfiguration of the debug logic, enabling rapid switching of variable observation between debug iterations. In addition, our overlay provides additional debug capability, such as selective function tracing and conditional buffer freeze points. We explore the area overhead of these different overlay features, showing a basic overlay with only a 1.7% increase in area overhead from the baseline debug instrumentation, while a deluxe variant offers 2x-7x improvement in trace buffer memory utilization with conditional buffer freeze support.