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PESTT: PESTT EDUCATIONAL SOFTWARE TESTING TOOL
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If CFG stop working #10

Closed fcmartins closed 12 years ago

fcmartins commented 12 years ago

The generation of a simple if CFG is resulting in a null pointer exception.

Example:

public void ifThen () {
    if (x == 0) 
        x = 2;
}

Exception:

ENTRY org.eclipse.ui 4 0 2012-02-26 13:05:33.077 !MESSAGE Unhandled event loop exception !STACK 0 java.lang.NullPointerException at graphvisitors.DepthFirstGraphVisitor.visitGraph(DepthFirstGraphVisitor.java:68) at view.GraphsCreator.createGraphs(GraphsCreator.java:30) at view.ViewGraph.create(ViewGraph.java:25) at handler.RefreshHandler.execute(RefreshHandler.java:60) at handler.DrawGraphHandler.execute(DrawGraphHandler.java:11) at org.eclipse.ui.internal.handlers.HandlerProxy.execute(HandlerProxy.java:293) at org.eclipse.core.commands.Command.executeWithChecks(Command.java:476) at org.eclipse.core.commands.ParameterizedCommand.executeWithChecks(ParameterizedCommand.java:508) at org.eclipse.ui.internal.handlers.HandlerService.executeCommand(HandlerService.java:169) at org.eclipse.ui.internal.handlers.SlaveHandlerService.executeCommand(SlaveHandlerService.java:241) at org.eclipse.ui.menus.CommandContributionItem.handleWidgetSelection(CommandContributionItem.java:829) at org.eclipse.ui.menus.CommandContributionItem.access$19(CommandContributionItem.java:815) at org.eclipse.ui.menus.CommandContributionItem$5.handleEvent(CommandContributionItem.java:805) at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84) at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4128) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1457) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1480) at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1465) at org.eclipse.swt.widgets.Widget.notifyListeners(Widget.java:1270) at org.eclipse.swt.widgets.Display.runDeferredEvents(Display.java:3974) at org.eclipse.swt.widgets.Display.readAndDispatch(Display.java:3613) at org.eclipse.ui.internal.Workbench.runEventLoop(Workbench.java:2696) at org.eclipse.ui.internal.Workbench.runUI(Workbench.java:2660) at org.eclipse.ui.internal.Workbench.access$4(Workbench.java:2494) at org.eclipse.ui.internal.Workbench$7.run(Workbench.java:674) at org.eclipse.core.databinding.observable.Realm.runWithDefault(Realm.java:332) at org.eclipse.ui.internal.Workbench.createAndRunWorkbench(Workbench.java:667) at org.eclipse.ui.PlatformUI.createAndRunWorkbench(PlatformUI.java:149) at org.eclipse.ui.internal.ide.application.IDEApplication.start(IDEApplication.java:123) at org.eclipse.equinox.internal.app.EclipseAppHandle.run(EclipseAppHandle.java:196) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.runApplication(EclipseAppLauncher.java:110) at org.eclipse.core.runtime.internal.adaptor.EclipseAppLauncher.start(EclipseAppLauncher.java:79) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:344) at org.eclipse.core.runtime.adaptor.EclipseStarter.run(EclipseStarter.java:179) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25) at java.lang.reflect.Method.invoke(Method.java:597) at org.eclipse.equinox.launcher.Main.invokeFramework(Main.java:622) at org.eclipse.equinox.launcher.Main.basicRun(Main.java:577) at org.eclipse.equinox.launcher.Main.run(Main.java:1410) at org.eclipse.equinox.launcher.Main.main(Main.java:1386)

fcmartins commented 12 years ago

When simplifying the CFG, sometimes the initial node was removed. The renumbering visitor was not able to visit the graph since the graph had no initial nodes. Asking for node 0 would return in a null reference, which was cause a null reference to be inserted as the initial node, and then... null pointer exception when later visiting the CFG.