The NetlistViewer tool is useful for debugging your netlist when simulation results are complex or conflicting with design constraints.
In most cases, this occurs when the output of a flip-flop is being fed back into the input without a reset, preset, or clear input. NetlistViewer can help you verify that such a flip-flop configuration exists in the design.
To locate and view the flip-flops:
Click NetlistViewer in the Design Flow window.
Zoom to locate the flip-flops.