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https://github.com/eclipse-cdt/cdt
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Bug 327375 control flow graph regression - dead connector nodes
basically for the code like if (a) return 1; else return 2; a++; // this should be a dead code node but we don't check connector node of "if" and don't add it to dead nodes graph resulting it this code not being marked as dead, which can lead to false positives or false negatives for checkers that use that. Same apply for other control statements... Change-Id: Iafb4b48ca960f0ffab2c0265285a31cb08eb0d11
This commit is contained in:
Alena Laskavaia
Gerrit Code Review @ Eclipse.org
parent
3edc86361c
commit
3cf5ec86ee
3 changed files with 135 additions and 35 deletions
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@ -312,16 +312,23 @@ public class ControlFlowGraphBuilder {
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addOutgoing(ifNode, elseNode);
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IBasicBlock els = createSubGraph(elseNode, body.getElseClause());
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addJump(els, mergeNode);
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fixConnector(mergeNode);
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return mergeNode;
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}
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protected void fixConnector(IConnectorNode mergeNode) {
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if (mergeNode.getIncomingSize()==0)
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dead.add(mergeNode); // dead connector node
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}
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private IBasicBlock createSwitch(IBasicBlock prev, IASTSwitchStatement body) {
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DecisionNode node = factory.createDecisionNode(body.getControllerExpression());
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addOutgoing(prev, node);
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IConnectorNode conn = factory.createConnectorNode();
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node.setMergeNode(conn);
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createSwitchBody(node, conn, body.getBody());
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return conn;
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IConnectorNode mergeNode = factory.createConnectorNode();
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node.setMergeNode(mergeNode);
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createSwitchBody(node, mergeNode, body.getBody());
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fixConnector(mergeNode);
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return mergeNode;
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}
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private void createSwitchBody(IDecisionNode switchNode, IConnectorNode mergeNode, IASTStatement body) {
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@ -380,9 +387,13 @@ public class ControlFlowGraphBuilder {
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IConnectorNode savedBreak = outerBreak;
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outerContinue = nContinue;
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outerBreak = nBreak;
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IBasicBlock endBody = createSubGraph(loopStart, forNode.getBody());
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outerContinue = savedContinue;
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outerBreak = savedBreak;
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IBasicBlock endBody = decision;
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try {
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endBody = createSubGraph(loopStart, forNode.getBody());
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} finally {
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outerContinue = savedContinue;
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outerBreak = savedBreak;
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}
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// inc
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IPlainNode inc = factory.createPlainNode(forNode.getIterationExpression());
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addOutgoing(endBody, nContinue);
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@ -393,6 +404,7 @@ public class ControlFlowGraphBuilder {
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IBranchNode loopEnd = factory.createBranchNode(IBranchNode.ELSE);
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addOutgoing(decision, loopEnd);
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addJump(loopEnd, nBreak);
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fixConnector(nBreak);
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return nBreak;
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}
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@ -432,6 +444,7 @@ public class ControlFlowGraphBuilder {
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IBranchNode loopEnd = factory.createBranchNode(IBranchNode.ELSE);
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addOutgoing(decision, loopEnd);
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addJump(loopEnd, nBreak);
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fixConnector(nBreak);
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return nBreak;
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}
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@ -453,16 +466,21 @@ public class ControlFlowGraphBuilder {
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IConnectorNode savedBreak = outerBreak;
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outerContinue = nContinue;
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outerBreak = nBreak;
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IBasicBlock endBody = createSubGraph(loopStart, body.getBody());
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// Restore
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outerContinue = savedContinue;
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outerBreak = savedBreak;
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IBasicBlock endBody = decision;
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try {
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endBody = createSubGraph(loopStart, body.getBody());
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} finally {
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// Restore
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outerContinue = savedContinue;
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outerBreak = savedBreak;
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}
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// Backward jump
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addJump(endBody, nContinue, true);
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// Connect with else branch
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IBranchNode loopEnd = factory.createBranchNode(IBranchNode.ELSE);
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addOutgoing(decision, loopEnd);
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addJump(loopEnd, nBreak);
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fixConnector(nBreak);
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return nBreak;
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}
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@ -500,6 +518,7 @@ public class ControlFlowGraphBuilder {
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// Add break connector
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decision.setMergeNode(nBreak);
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addJump(loopEnd, nBreak);
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fixConnector(nBreak);
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return nBreak;
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}
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@ -10,6 +10,7 @@
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*******************************************************************************/
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package org.eclipse.cdt.codan.core.cfg;
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import java.util.ArrayList;
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import java.util.Collection;
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import java.util.Iterator;
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@ -34,7 +35,7 @@ import org.eclipse.cdt.core.dom.ast.c.CASTVisitor;
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import org.eclipse.cdt.core.parser.ParserLanguage;
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/**
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* TODO: add description
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* Tests for ControlFlowGraph
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*/
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public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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ControlFlowGraph graph;
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@ -111,7 +112,7 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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fail("Block " + node + " inconsitent next/prev " + b);
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}
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if (node instanceof IDecisionNode && decision) {
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assertTrue("decision node outgoing size " + node.getOutgoingSize(), node.getOutgoingSize() > 1);
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assertTrue("decision node outgoing size " + node.getOutgoingSize(), node.getOutgoingSize() >= 1);
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assertNotNull(((IDecisionNode) node).getMergeNode());
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}
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}
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@ -159,10 +160,12 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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parse(code, ParserLanguage.C, true);
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processAst(tu);
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}
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private void buildCfg_CPP(String code) {
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parse(code, ParserLanguage.CPP, true);
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processAst(tu);
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}
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/**
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* @param des
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* @return
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@ -434,17 +437,16 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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IBasicBlock bElse = branchEnd(des, IBranchNode.ELSE);
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IBasicBlock m2 = jumpEnd(branchEnd(des, IBranchNode.THEN));
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IBasicBlock m1 = jumpEnd(bElse);
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assertNull(m2);
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assertNotNull(m1);
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}
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// int test1_f()
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// {
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// while (1)
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// {
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// }
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// }
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// int test1_f()
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// {
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// while (1)
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// {
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// }
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// }
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public void test_infiniloop() {
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buildCfg_C(getAboveComment());
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checkCfg(false);
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@ -456,7 +458,6 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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IBasicBlock bThen = branchEnd(des, IBranchNode.THEN);
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IBasicBlock m2 = jumpEnd(bThen);
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IBasicBlock m1 = jumpEnd(bElse);
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assertNotNull(m2);
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assertNull(m1);
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}
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@ -469,7 +470,6 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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public void test_for() {
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buildCfg_CPP(getAboveComment());
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checkCfg(false);
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IStartNode startNode = graph.getStartNode();
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IPlainNode decl = (IPlainNode) startNode.getOutgoing();
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IConnectorNode conn = (IConnectorNode) decl.getOutgoing();
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@ -478,7 +478,6 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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IPlainNode bThen = (IPlainNode) branchEnd(des, IBranchNode.THEN);
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assertEquals("bar();", data(bThen));
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IBasicBlock bElse = branchEnd(des, IBranchNode.ELSE);
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IBasicBlock m1 = jumpEnd(bElse);
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IBasicBlock m2 = bThen.getOutgoing();
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assertNotNull(m1);
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@ -494,7 +493,6 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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public void test_range_loop() {
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buildCfg_CPP(getAboveComment());
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checkCfg(false);
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IStartNode startNode = graph.getStartNode();
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IPlainNode decl = (IPlainNode) startNode.getOutgoing();
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IConnectorNode conn = (IConnectorNode) decl.getOutgoing();
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@ -511,24 +509,23 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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assertEquals("", data(((IConnectorNode) m2).getOutgoing())); // increment
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}
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// int main() {
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// goto b;
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// a:
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// return 2;
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// b:
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// goto a;
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// }
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// int main() {
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// goto b;
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// a:
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// return 2;
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// b:
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// goto a;
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// }
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public void test_bad_labels() {
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buildAndCheck(getAboveComment());
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assertEquals(0, graph.getUnconnectedNodeSize());
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IStartNode startNode = graph.getStartNode();
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IJumpNode gotoB = (IJumpNode) startNode.getOutgoing();
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IJumpNode gotoB = (IJumpNode) startNode.getOutgoing();
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IConnectorNode bConn = gotoB.getJumpNode();
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IJumpNode gotoA = (IJumpNode) bConn.getOutgoing();
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IJumpNode gotoA = (IJumpNode) bConn.getOutgoing();
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IConnectorNode aConn = gotoA.getJumpNode();
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IExitNode ret = (IExitNode) aConn.getOutgoing();
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IExitNode ret = (IExitNode) aConn.getOutgoing();
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assertEquals("return 2;", data(ret));
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}
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// int main(int a) {
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@ -550,4 +547,74 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase {
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buildAndCheck(getAboveComment());
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assertEquals(0, graph.getUnconnectedNodeSize());
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}
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// int main() {
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// return 1;
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// a:
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// return 2;
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// b:
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// goto a;
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// }
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public void test_dead_labels() {
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buildAndCheck(getAboveComment());
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assertEquals(1, graph.getUnconnectedNodeSize());
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IStartNode startNode = graph.getStartNode();
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IExitNode ret = (IExitNode) startNode.getOutgoing();
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assertEquals("return 1;", data(ret));
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IBranchNode labelB = (IBranchNode) graph.getUnconnectedNodeIterator().next(); // BranchNode: b:
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ArrayList<IBasicBlock> res = new ArrayList<>();
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graph.getNodes(labelB, res);
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assertEquals(6, res.size());
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IJumpNode gotoA = (IJumpNode) ((IConnectorNode) labelB.getOutgoing()).getOutgoing();
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IConnectorNode aConn = gotoA.getJumpNode();
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IExitNode ret2 = (IExitNode) aConn.getOutgoing();
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assertEquals("return 2;", data(ret2));
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assertTrue(res.contains(gotoA));// goto a;
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assertTrue(res.contains(aConn));
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assertTrue(res.contains(ret2)); // return 2;
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assertTrue(res.contains(ret2.getIncoming())); // Branch Node: a:
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}
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// int main(int a) {
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// if (a) {
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// return 1;
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// } else {
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// return 2;
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// }
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// a++;
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// }
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public void test_dead_connector() {
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buildAndCheck(getAboveComment());
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assertEquals(1, graph.getUnconnectedNodeSize());
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IConnectorNode connIf = (IConnectorNode) graph.getUnconnectedNodeIterator().next();
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assertEquals("a++;", data(connIf.getOutgoing()));
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}
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// int main(int a) {
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// for (;1;a++) {
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// return 1;
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// }
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// a--;
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// }
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public void test_dead_connector_for() {
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buildAndCheck(getAboveComment());
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assertEquals(2, graph.getUnconnectedNodeSize());
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IConnectorNode conn = (IConnectorNode) graph.getUnconnectedNodeIterator().next();
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assertEquals("a++", data(conn.getOutgoing()));
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}
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// int main(int a) {
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// while (0) {
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// return 1;
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// }
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//
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// a++;
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// }
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public void test_dead_connector_while() {
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buildAndCheck(getAboveComment());
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assertEquals(1, graph.getUnconnectedNodeSize());
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IBranchNode trueBranch = (IBranchNode) graph.getUnconnectedNodeIterator().next();
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assertEquals("return 1;", data(trueBranch.getOutgoing()));
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}
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}
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@ -223,6 +223,20 @@ public class ReturnCheckerTest extends CheckerTestCase {
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loadCodeAndRunCpp(getAboveComment());
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checkNoErrors();
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}
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//int bar(int foo)
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//{
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// if(foo)
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// return 0;
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// else
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// return 0;
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// foo++;
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//}
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public void testBranchesDeadCode_Bug343767() {
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loadCodeAndRunCpp(getAboveComment());
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checkNoErrors();
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}
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// int f()
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// {
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// switch (g()) {
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