Bug 335909 - adjusted cfg generation for switch and dead code

codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java

@@ -13,6 +13,7 @@ package org.eclipse.cdt.codan.core.cxx.internal.model.cfg;
 import java.util.ArrayList;
 import java.util.Collection;
 import java.util.HashMap;
+import java.util.Iterator;
 
 import org.eclipse.cdt.codan.core.model.cfg.IBasicBlock;
 import org.eclipse.cdt.codan.core.model.cfg.IBranchNode;
@@ -22,6 +23,7 @@ import org.eclipse.cdt.codan.core.model.cfg.IDecisionNode;
 import org.eclipse.cdt.codan.core.model.cfg.IExitNode;
 import org.eclipse.cdt.codan.core.model.cfg.IJumpNode;
 import org.eclipse.cdt.codan.core.model.cfg.IPlainNode;
+import org.eclipse.cdt.codan.core.model.cfg.ISingleOutgoing;
 import org.eclipse.cdt.codan.core.model.cfg.IStartNode;
 import org.eclipse.cdt.codan.internal.core.cfg.AbstractBasicBlock;
 import org.eclipse.cdt.codan.internal.core.cfg.DecisionNode;
@@ -80,12 +82,35 @@ public class ControlFlowGraphBuilder {
 			returnExit.setStartNode(start);
 			addOutgoing(last, returnExit);
 			exits.add(returnExit);
+			if (dead.size() > 0) {
+				for (Iterator iterator = dead.iterator(); iterator.hasNext();) {
+					IBasicBlock ds = (IBasicBlock) iterator.next();
+					IBasicBlock dl = findLast(ds);
+					if (dl != null && dl.getOutgoingSize() == 0
+							&& dl != returnExit) {
+						((AbstractBasicBlock) dl).addOutgoing(returnExit);
+					}
+				}
+			}
 		}
 		CxxControlFlowGraph graph = new CxxControlFlowGraph(start, exits);
 		graph.setUnconnectedNodes(dead);
 		return graph;
 	}
 
+	public IBasicBlock findLast(IBasicBlock node) {
+		if (node instanceof IJumpNode)
+			return null;
+		if (node.getOutgoingSize() == 0)
+			return node;
+		if (node instanceof ISingleOutgoing) {
+			return findLast(((ISingleOutgoing) node).getOutgoing());
+		} else if (node instanceof IDecisionNode) {
+			return findLast(((IDecisionNode) node).getMergeNode().getOutgoing());
+		}
+		return node;
+	}
+
 	/**
 	 * @param start2
 	 * @param body
@@ -335,6 +360,7 @@ public class ControlFlowGraphBuilder {
 			IBasicBlock last = createSubGraph(prev, elem);
 			prev = last;
 		}
+		addJump(prev, mergeNode);
 	}
 
 	/**

codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java

@@ -61,38 +61,58 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
 		ast.accept(visitor);
 	}
 
+	private void checkCfg() {
+		checkCfg(true);
+	}
+
 	/**
 	 * 
 	 */
-	private void checkCfg() {
+	private void checkCfg(boolean decision) {
 		assertNotNull(graph);
 		assertNotNull(graph.getStartNode());
 		Collection<IBasicBlock> nodes = graph.getNodes();
 		for (Iterator<IBasicBlock> iterator = nodes.iterator(); iterator
 				.hasNext();) {
 			IBasicBlock node = iterator.next();
-			checkNode(node);
+			checkNode(node, decision);
 		}
 	}
 
 	/**
 	 * @param node
 	 */
-	private void checkNode(IBasicBlock node) {
+	private void checkNode(IBasicBlock node, boolean decision) {
 		IBasicBlock[] incomingNodes = node.getIncomingNodes();
-		for (int i = 0; i < incomingNodes.length; i++) {
+		nodes: for (int i = 0; i < incomingNodes.length; i++) {
 			IBasicBlock b = incomingNodes[i];
-			if (!contains(node, b.getOutgoingNodes()))
+			if (b == null) {
+				// check if dead node
+				Iterator<IBasicBlock> iterator = graph
+						.getUnconnectedNodeIterator();
+				boolean dead = false;
+				for (; iterator.hasNext();) {
+					IBasicBlock d = iterator.next();
+					if (node == d) {
+						dead = true;
+						break;
+					}
+				}
+				if (!dead)
+					fail("Block " + node + " prev is null");
+			} else if (!contains(node, b.getOutgoingNodes()))
 				fail("Block " + node + " inconsitent prev/next " + b);
 		}
 		IBasicBlock[] outgoingNodes = node.getOutgoingNodes();
 		for (int i = 0; i < outgoingNodes.length; i++) {
 			IBasicBlock b = outgoingNodes[i];
+			if (b == null)
+				fail("Block " + node + " next is null");
 			if (!contains(node, b.getIncomingNodes()))
 				fail("Block " + node + " inconsitent next/prev " + b);
 		}
-		if (node instanceof IDecisionNode) {
+		if (node instanceof IDecisionNode && decision) {
-			assertTrue("decision node outgping size",
+			assertTrue("decision node outgoing size " + node.getOutgoingSize(),
 					node.getOutgoingSize() > 1);
 			assertNotNull(((IDecisionNode) node).getMergeNode());
 		}
@@ -360,4 +380,36 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
 		IBasicBlock m1 = jumpEnd(bElse);
 		assertSame(m1, m2);
 	}
+
+	//	 foo() {
+	//	   switch (0) {
+	//     case 1: ;
+	//	   }
+	//	 }
+	public void test_switch1() {
+		buildCfg(getAboveComment(), false);
+		checkCfg(false);
+	}
+
+	//	 foo() {
+	//	   switch (0) {
+	//     case 1: break;
+	//	   }
+	//	 }
+	public void test_switchbreak() {
+		buildCfg(getAboveComment(), false);
+		checkCfg(false);
+	}
+
+	//	 foo() {
+	//	   switch (0) {
+	//	         a++;
+	//	   }
+	//	 }
+	public void test_switchdead() {
+		buildCfg(getAboveComment(), false);
+		checkCfg(false);
+		IStartNode startNode = graph.getStartNode();
+		assertEquals(1, graph.getUnconnectedNodeSize());
+	}
 }

codan/org.eclipse.cdt.codan.core/src/org/eclipse/cdt/codan/internal/core/cfg/ControlFlowGraph.java

@@ -135,6 +135,8 @@ public class ControlFlowGraph implements IControlFlowGraph {
 	 * @param result
 	 */
 	private void getNodes(IBasicBlock start, Collection<IBasicBlock> result) {
+		if (start == null)
+			return; // huh
 		if (result.contains(start))
 			return;
 		result.add(start);

codan/org.eclipse.cdt.codan.core/src/org/eclipse/cdt/codan/internal/core/cfg/PlainNode.java

@@ -29,6 +29,8 @@ public class PlainNode extends AbstractSingleIncomingNode implements IPlainNode
 	}
 
 	public int getOutgoingSize() {
+		if (next == null)
+			return 0;
 		return 1;
 	}