The Ideal Graph Visualizer is a tool developed to help examine the intermediate representation of C2 which is commonly referred to as the "ideal graph". It was developed in collaboration with the University of Linz in Austria and has been included as part of hotspot since that was the primary target of the tool. The tool itself is fairly general with only a few modules that contain C2 specific elements.
Papers describing the tool itself is available at Publications and a rough user guide will be available soon. The source is part of the hotspot repository in the src/share/tools/IdealGraphVisualizer directory.