8283930: IGV: add toggle button to show/hide empty blocks in CFG view

src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/BlockConnection.java

@@ -100,11 +100,6 @@ public void setControlPoints(List<Point> list) {
         controlPoints = list;
     }
 
-    @Override
-    public boolean isAlwaysVisible() {
-        return true;
-    }
-
     @Override
     public boolean hasSlots() {
         return false;

src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/Connection.java

@@ -41,8 +41,6 @@ public enum ConnectionStyle {
 
     public String getToolTipText();
 
-    public boolean isAlwaysVisible();
-
     public boolean hasSlots();
 
 }

src/utils/IdealGraphVisualizer/Graph/src/main/java/com/sun/hotspot/igv/graph/FigureConnection.java

@@ -148,11 +148,6 @@ public void setControlPoints(List<Point> list) {
         controlPoints = list;
     }
 
-    @Override
-    public boolean isAlwaysVisible() {
-        return false;
-    }
-
     @Override
     public boolean hasSlots() {
         return true;

src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramScene.java

@@ -605,17 +605,22 @@ private void smallUpdate(boolean relayout) {
     }
 
     private boolean isVisible(Connection c) {
-        if (getModel().getShowCFG()) {
-            return c.isAlwaysVisible();
-        }
-        FigureWidget w1 = getWidget(c.getFrom().getVertex());
-        FigureWidget w2 = getWidget(c.getTo().getVertex());
-
-        if (w1.isVisible() && w2.isVisible()) {
-            return true;
+        // Generally, a connection is visible if its source and destination
+        // widgets are visible. An exception is Figure connections in the CFG
+        // view, which are never shown.
+        if (getModel().getShowCFG() && c instanceof FigureConnection) {
+            return false;
+        }
+        Widget w1, w2;
+        if (c instanceof BlockConnection) {
+            w1 = getWidget(((Block)c.getFromCluster()).getInputBlock());
+            w2 = getWidget(((Block)c.getToCluster()).getInputBlock());
+        } else {
+            assert (c instanceof FigureConnection);
+            w1 = getWidget(c.getFrom().getVertex());
+            w2 = getWidget(c.getTo().getVertex());
         }
-
-        return false;
+        return w1.isVisible() && w2.isVisible();
     }
 
     private void relayout(Set<Widget> oldVisibleWidgets) {
@@ -697,10 +702,21 @@ private void doCFGLayout(HashSet<Figure> figures, HashSet<Connection> edges) {
                 }
             }
         }
-        // Add connections for CFG edges.
-        edges.addAll(diagram.getBlockConnections());
+        // Add visible connections for CFG edges.
+        for (BlockConnection c : diagram.getBlockConnections()) {
+            if (isVisible(c)) {
+                edges.add(c);
+            }
+        }
         m.setSubManager(new LinearLayoutManager(figureRank));
-        m.setClusters(new HashSet<>(diagram.getBlocks()));
+        Set<Block> visibleBlocks = new HashSet<Block>();
+        for (Block b : diagram.getBlocks()) {
+            BlockWidget w = getWidget(b.getInputBlock());
+            if (w.isVisible()) {
+                visibleBlocks.add(b);
+            }
+        }
+        m.setClusters(new HashSet<>(visibleBlocks));
         m.doLayout(new LayoutGraph(edges, figures));
     }
 
@@ -795,8 +811,10 @@ private void relayoutWithoutLayout(Set<Widget> oldVisibleWidgets) {
 
         if (getModel().getShowCFG()) {
             for (BlockConnection c : diagram.getBlockConnections()) {
-                SceneAnimator anim = animator;
-                processOutputSlot(lastLineCache, null, Collections.singletonList(c), 0, null, null, offx2, offy2, anim);
+                if (isVisible(c)) {
+                    SceneAnimator anim = animator;
+                    processOutputSlot(lastLineCache, null, Collections.singletonList(c), 0, null, null, offx2, offy2, anim);
+                }
             }
         }
 
@@ -1211,18 +1229,19 @@ private void updateHiddenNodes(Set<Integer> newHiddenNodes, boolean doRelayout)
                     w.setVisible(false);
                 }
             }
-            visibleBlocks.clear();
-            for (InputBlock b : diagram.getGraph().getBlocks()) {
-                if (!b.isArtificial()) {
-                    visibleBlocks.add(b);
-                }
+            if (getModel().getShowEmptyBlocks()) {
+                // Add remaining blocks.
+                visibleBlocks.addAll(diagram.getGraph().getBlocks());
             }
         }
 
         if (getModel().getShowBlocks() || getModel().getShowCFG()) {
             for (InputBlock b : diagram.getGraph().getBlocks()) {
 
-                boolean visibleAfter = visibleBlocks.contains(b);
+                // A block is visible if it is marked as such, except for
+                // artificial or null blocks in the CFG view.
+                boolean visibleAfter = visibleBlocks.contains(b) &&
+                    !(getModel().getShowCFG() && (b.isArtificial() || b.getNodes().isEmpty()));
 
                 BlockWidget w = getWidget(b);
                 if (visibleAfter) {

src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/DiagramViewModel.java

@@ -62,6 +62,7 @@ public class DiagramViewModel extends RangeSliderModel implements ChangedListene
     private boolean showBlocks;
     private boolean showCFG;
     private boolean showNodeHull;
+    private boolean showEmptyBlocks;
     private boolean hideDuplicates;
     private ChangedListener<FilterChain> filterChainChangedListener = new ChangedListener<FilterChain>() {
 
@@ -166,6 +167,15 @@ public void setShowNodeHull(boolean b) {
         viewPropertiesChangedEvent.fire();
     }
 
+    public boolean getShowEmptyBlocks() {
+        return showEmptyBlocks;
+    }
+
+    public void setShowEmptyBlocks(boolean b) {
+        showEmptyBlocks = b;
+        viewPropertiesChangedEvent.fire();
+    }
+
     public boolean getHideDuplicates() {
         return hideDuplicates;
     }
@@ -194,6 +204,7 @@ public DiagramViewModel(Group g, FilterChain filterChain, FilterChain sequenceFi
         this.showBlocks = Settings.get().getInt(Settings.DEFAULT_VIEW, Settings.DEFAULT_VIEW_DEFAULT) == Settings.DefaultView.CLUSTERED_SEA_OF_NODES;
         this.showCFG = Settings.get().getInt(Settings.DEFAULT_VIEW, Settings.DEFAULT_VIEW_DEFAULT) == Settings.DefaultView.CONTROL_FLOW_GRAPH;
         this.showNodeHull = true;
+        this.showEmptyBlocks = true;
         this.group = g;
         filterGraphs();
         assert filterChain != null;

src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/EditorTopComponent.java

@@ -99,6 +99,7 @@ public final class EditorTopComponent extends TopComponent implements PropertyCh
     private OverviewAction overviewAction;
     private HideDuplicatesAction hideDuplicatesAction;
     private PredSuccAction predSuccAction;
+    private ShowEmptyBlocksAction showEmptyBlocksAction;
     private SelectionModeAction selectionModeAction;
     private PanModeAction panModeAction;
     private boolean notFirstTime;
@@ -279,6 +280,13 @@ public void changed(DiagramViewModel source) {
         toolBar.add(button);
         predSuccAction.addPropertyChangeListener(this);
 
+        showEmptyBlocksAction = new ShowEmptyBlocksAction();
+        button = new JToggleButton(showEmptyBlocksAction);
+        button.setSelected(true);
+        button.setEnabled(Settings.get().getInt(Settings.DEFAULT_VIEW, Settings.DEFAULT_VIEW_DEFAULT) == Settings.DefaultView.CONTROL_FLOW_GRAPH);
+        toolBar.add(button);
+        showEmptyBlocksAction.addPropertyChangeListener(this);
+
         hideDuplicatesAction = new HideDuplicatesAction();
         hideDuplicatesButton = new JToggleButton(hideDuplicatesAction);
         hideDuplicatesButton.setSelected(false);
@@ -546,6 +554,9 @@ public void propertyChange(PropertyChangeEvent evt) {
         if (evt.getSource() == this.predSuccAction) {
             boolean b = (Boolean) predSuccAction.getValue(PredSuccAction.STATE);
             this.getModel().setShowNodeHull(b);
+        } else if (evt.getSource() == this.showEmptyBlocksAction) {
+            boolean b = (Boolean) showEmptyBlocksAction.getValue(ShowEmptyBlocksAction.STATE);
+            this.getModel().setShowEmptyBlocks(b);
         } else if (evt.getSource() == this.overviewAction) {
             boolean b = (Boolean) overviewAction.getValue(OverviewAction.STATE);
             if (b) {
@@ -556,12 +567,15 @@ public void propertyChange(PropertyChangeEvent evt) {
         } else if (evt.getSource() == this.seaLayoutAction) {
             boolean b = seaLayoutAction.isSelected();
             this.getModel().setShowSea(b);
+            this.showEmptyBlocksAction.setEnabled(false);
         } else if (evt.getSource() == this.blockLayoutAction) {
             boolean b = blockLayoutAction.isSelected();
             this.getModel().setShowBlocks(b);
+            this.showEmptyBlocksAction.setEnabled(false);
         } else if (evt.getSource() == this.cfgLayoutAction) {
             boolean b = cfgLayoutAction.isSelected();
             this.getModel().setShowCFG(b);
+            this.showEmptyBlocksAction.setEnabled(true);
         } else if (evt.getSource() == this.hideDuplicatesAction) {
             boolean b = (Boolean) hideDuplicatesAction.getValue(HideDuplicatesAction.STATE);
             this.getModel().setHideDuplicates(b);

src/utils/IdealGraphVisualizer/View/src/main/java/com/sun/hotspot/igv/view/actions/ShowEmptyBlocksAction.java

@@ -0,0 +1,53 @@
+/*
+ * Copyright (c) 2022, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+package com.sun.hotspot.igv.view.actions;
+
+import java.awt.event.ActionEvent;
+import javax.swing.AbstractAction;
+import javax.swing.Action;
+import javax.swing.ImageIcon;
+import org.openide.util.ImageUtilities;
+
+public class ShowEmptyBlocksAction extends AbstractAction {
+
+    private boolean state;
+    public static final String STATE = "state";
+
+    public ShowEmptyBlocksAction() {
+        state = true;
+        putValue(AbstractAction.SMALL_ICON, new ImageIcon(ImageUtilities.loadImage(iconResource())));
+        putValue(STATE, true);
+        putValue(Action.SHORT_DESCRIPTION, "Show empty blocks in control-flow graph view");
+    }
+
+    @Override
+    public void actionPerformed(ActionEvent ev) {
+        this.state = !state;
+        this.putValue(STATE, state);
+    }
+
+    protected String iconResource() {
+        return "com/sun/hotspot/igv/view/images/showEmptyBlocks.png";
+    }
+}

src/utils/IdealGraphVisualizer/View/src/main/resources/com/sun/hotspot/igv/view/layer.xml

@@ -17,6 +17,7 @@
             <file name="com-sun-hotspot-igv-view-actions-ZoomOutAction.instance"><attr name="position" intvalue="2001"/></file>
             <file name="com-sun-hotspot-igv-view-actions-OverviewAction.instance"><attr name="position" intvalue="2001"/></file>
             <file name="com-sun-hotspot-igv-view-actions-PredSuccAction.instance"><attr name="position" intvalue="2001"/></file>
+            <file name="com-sun-hotspot-igv-view-actions-ShowEmptyBlocksAction.instance"><attr name="position" intvalue="2001"/></file>
             <file name="com-sun-hotspot-igv-view-actions-EnableSeaLayoutAction.instance"><attr name="position" intvalue="2001"/></file>
             <file name="com-sun-hotspot-igv-view-actions-EnableBlockLayoutAction.instance"><attr name="position" intvalue="2001"/></file>
             <file name="com-sun-hotspot-igv-view-actions-EnableCFGLayoutAction.instance"><attr name="position" intvalue="2001"/></file>