Ideal Graph Visualizer throws the following exception error when drawing the control flow of an Ideal graph before the global code motion phase (see the attached screenshot):

java.lang.AssertionError
at org.netbeans.api.visual.graph.GraphScene.addEdge(GraphScene.java:154)
at com.sun.hotspot.igv.controlflow.ControlFlowScene.setGraph(ControlFlowScene.java:113)
at com.sun.hotspot.igv.controlflow.ControlFlowTopComponent$1.run(ControlFlowTopComponent.java:145)
at java.awt.event.InvocationEvent.dispatch(InvocationEvent.java:311)
at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
at java.awt.EventQueue.access$500(EventQueue.java:97)
at java.awt.EventQueue$3.run(EventQueue.java:709)
at java.awt.EventQueue$3.run(EventQueue.java:703)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:74)
at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
at org.netbeans.core.TimableEventQueue.dispatchEvent(TimableEventQueue.java:159)
[catch] at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:205)
at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

STEPS TO REPRODUCE IT:

1. $ cd src/utils/IdealGraphVisualizer
2. $ export JAVA_HOME=... (JDK 8)
3. $ ant build
4. $ sh igv.sh
5. Window -> Control Flow
6. File -> Open -> select foo.xml -> OK
7. In the "Outline" window group, expand "static jint Factorial.fac(jint)" and double-click on "After Parsing"
8. The exception is triggered

The Ideal Graph Visualizer runs on the following specific JDK version:

$JAVA_HOME/bin/java -version
java version "1.8.0_261"
Java(TM) SE Runtime Environment (build 1.8.0_261-b12)
Java HotSpot(TM) 64-Bit Server VM (build 25.261-b12, mixed mode)