Automated Activation of Multiple Targets in RTL Models using Concolic Testing
Yangdi Lyu, Alif Ahmed and Prabhat Mishra
University of Florida, Gainesville, Florida, USA
ABSTRACT
Simulation is widely used for validation of Register-Transfer-Level (RTL) models. While simulating with millions of random (or constrained-random) tests can cover majority of the targets (functional scenarios), the number of remaining targets can still be huge (hundreds or thousands) in case of today’s industrial designs. Prior work on directed test generation using concolic testing can cover only one target at a time. A naive extension of prior work to activate the remaining targets would be infeasible due to wasted effort in multiple overlapping searches. In this paper, we propose an automated test generation technique for activating multiple targets in RTL models using concolic testing. This paper makes three important contributions. First, it efficiently prunes the targets that can be covered by the tests generated for activating the other targets. Next, it minimizes the overlapping searches while trying to generate tests for activating multiple targets. Finally, our approach effectively utilizes clustering of related targets as well as common path sharing between the targets in the same cluster to drastically reduce the test generation time. Experimental results demonstrate that our approach significantly outperforms the existing methods in terms of overall coverage (up to 5X, 1.2X on average) as well as test generation time (up to 146X, 80X on average).
