Hardware-Based Load Value Trace Filtering for On-the-Fly Debugging

Capturing program and data traces during program execution unobtrusively on-the-fly is crucial in debugging and testing of cyber-physical systems. However, tracing a complete program unobtrusively is often cost-prohibitive, requiring large on-chip trace buffers and wide trace ports. This paper describes a new hardware-based load data value filtering technique called Cache First-access Tracking. Coupled with an effective variable encoding scheme, this technique achieves a significant reduction of load data value traces, from 5.86 to 56.39 times depending on the data cache size, thus enabling cost-effective unobtrusive on-the-fly tracing and debugging.