In-Circuit Assertions and Exceptions for Reconfigurable Hardware Design

We present an approach to enable run-time, in-circuit assertions and exceptions in reconfigurable hardware designs. Static, compile-time checking, including formal verification, can catch many errors before a reconfigurable design is implemented. However, many other errors cannot be caught by static approaches, including those due to run-time data. Our approach allows users to add run-time assertions and exceptions to a design, giving multiple ways to handle run-time errors. We also allow imprecise assertions and exceptions, so that the origin of a failed assertion or raised exception is blurred. Users can take advantage of exception imprecision to trade performance for accurate location of errors. Our work includes a high-level approach to adding assertions and exceptions to a design, a concrete implementation for Maxeler streaming designs, and an evaluation. Results show low overhead for supporting assertions and exceptions in hardware design targeting FPGAs. For example, the cost of including assertions lies between 5% in lookup tables and 15% in Block RAMs in addition to the area used by the original design, due to logic used to implement assertion conditions, and buffers used to store assertion results. Furthermore, imprecision gives immediate benefits and up to 48% speedup over precise exceptions.