Path directed abstraction and refinement in SAT-based design debugging

Abstract

The past decade has seen a disproportionate amount of resources dedicated towards verification as compared to actual design. It is reported that one third of this overhead is due to the resource-intensive task of manual debugging. To relieve this burden, this work introduces the novel concept of path directed debugging within a window-based abstraction/refinement framework. The algorithm divides the error trace into non-overlapping time-windows where each window is analyzed separately. Subsequent windows are replaced with abstracted over-approximations derived from failing paths in the time domain. Using this abstracted model, each solution found is processed through an additional verification step that removes spurious solutions and simultaneously refines the problem. This paper also develops the theory that shows that the proposed approach is complete, a fact that mitigates the incompleteness inherent in past time-window based debugging methods. Experimental results on industrial designs with long error traces show a 55% decrease in peak memory usage resulting in 78% more instances being solved when compared to previous work.