From db43e03878e285348d08ddab9ae034edf669da70 Mon Sep 17 00:00:00 2001 From: Alena Laskavaia Date: Wed, 18 Jun 2014 22:12:15 -0400 Subject: [PATCH] Bug 394521 Do Constant folding propagation when building CFG When building control flow graph we can consider constants and not add some branches in decisions nodes, that make CFG more accurate and elimate some false positives Change-Id: I19c623e1e6d2dc7416a0e796a98168df7a976111 Signed-off-by: Alena Laskavaia Reviewed-on: https://git.eclipse.org/r/28726 --- .../model/cfg/ControlFlowGraphBuilder.java | 31 +++++++++++-- .../codan/core/cfg/ControlFlowGraphTest.java | 46 ++++++++++++++++++- .../internal/checkers/ReturnCheckerTest.java | 22 +++++++++ 3 files changed, 94 insertions(+), 5 deletions(-) diff --git a/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java b/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java index 69809d2ae60..139b4af08b2 100644 --- a/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java +++ b/codan/org.eclipse.cdt.codan.core.cxx/src/org/eclipse/cdt/codan/core/cxx/internal/model/cfg/ControlFlowGraphBuilder.java @@ -52,8 +52,10 @@ import org.eclipse.cdt.core.dom.ast.IASTStatement; import org.eclipse.cdt.core.dom.ast.IASTSwitchStatement; import org.eclipse.cdt.core.dom.ast.IASTUnaryExpression; import org.eclipse.cdt.core.dom.ast.IASTWhileStatement; +import org.eclipse.cdt.core.dom.ast.IValue; import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTCatchHandler; import org.eclipse.cdt.core.dom.ast.cpp.ICPPASTTryBlockStatement; +import org.eclipse.cdt.internal.core.dom.parser.Value; /** * This class creates C control flow graph @@ -463,14 +465,37 @@ public class ControlFlowGraphBuilder { if (prev instanceof IExitNode || prev == null) { dead.add(node); return; - } else if (prev instanceof ICfgData) { - if (prev instanceof IDecisionNode && !(node instanceof IBranchNode)) { + } + if (prev instanceof IDecisionNode) { + if (node instanceof IBranchNode) { + IDecisionNode decisionNode = (IDecisionNode) prev; + if (isConstant(decisionNode, 1) && ((IBranchNode) node).getLabel().equals(IBranchNode.ELSE)) { + dead.add(node); + return; + } else if (isConstant(decisionNode, 0) && ((IBranchNode) node).getLabel().equals(IBranchNode.THEN)) { + dead.add(node); + return; + } + } else { dead.add(node); return; } - ((AbstractBasicBlock) prev).addOutgoing(node); } + ((AbstractBasicBlock) prev).addOutgoing(node); if (!(node instanceof IStartNode)) ((AbstractBasicBlock) node).addIncoming(prev); } + + private boolean isConstant(IDecisionNode node, long testvalue) { + if (node instanceof ICfgData) { + IASTNode ast = (IASTNode) ((ICfgData) node).getData(); + if (ast instanceof IASTExpression) { + IValue dvalue = Value.create((IASTExpression) ast, 5); + Long numericalValue = dvalue.numericalValue(); + if (numericalValue==null) return false; + return (numericalValue==testvalue); + } + } + return false; + } } diff --git a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java index dd6c6d20592..d483f52b425 100644 --- a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java +++ b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/cfg/ControlFlowGraphTest.java @@ -294,8 +294,8 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase { assertEquals(1, graph.getUnconnectedNodeSize()); } - // foo() { - // int a=10, x=5; + // foo(int x) { + // int a=10; // if (a--) { // if (x<0) // a++; @@ -408,4 +408,46 @@ public class ControlFlowGraphTest extends CodanFastCxxAstTestCase { IStartNode startNode = graph.getStartNode(); assertEquals(1, graph.getUnconnectedNodeSize()); } + + // foo() { + // int a=10,x=5; + // if (x<0) + // a++; + // } + public void test_deadbranch() { + buildCfg(getAboveComment(), false); + checkCfg(false); + IStartNode startNode = graph.getStartNode(); + IPlainNode decl = (IPlainNode) startNode.getOutgoing(); + IDecisionNode des = (IDecisionNode) decl.getOutgoing(); + assertEquals("x<0", data(des)); + IBasicBlock bElse = branchEnd(des, IBranchNode.ELSE); + IBasicBlock m2 = jumpEnd(branchEnd(des, IBranchNode.THEN)); + IBasicBlock m1 = jumpEnd(bElse); + + assertNull(m2); + assertNotNull(m1); + } + +// int test1_f() +// { +// while (1) +// { +// } +// } + public void test_infiniloop() { + buildCfg(getAboveComment(), false); + checkCfg(false); + IStartNode startNode = graph.getStartNode(); + IConnectorNode conn = (IConnectorNode) startNode.getOutgoing(); + IDecisionNode des = (IDecisionNode) conn.getOutgoing(); + assertEquals("1", data(des)); + IBasicBlock bElse = branchEnd(des, IBranchNode.ELSE); + IBasicBlock bThen = branchEnd(des, IBranchNode.THEN); + IBasicBlock m2 = jumpEnd(bThen); + IBasicBlock m1 = jumpEnd(bElse); + + assertNotNull(m2); + assertNull(m1); + } } diff --git a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java index d56ff169f05..e1e1f1775c1 100644 --- a/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java +++ b/codan/org.eclipse.cdt.codan.core.test/src/org/eclipse/cdt/codan/core/internal/checkers/ReturnCheckerTest.java @@ -384,4 +384,26 @@ public class ReturnCheckerTest extends CheckerTestCase { checkNoErrors(); } +// int test1() { +// do { +// return 1; +// } while (0); +// } + public void testNoRetInfinitLoop() throws Exception { + // Bug 394521 + loadCodeAndRunCpp(getAboveComment()); + checkNoErrors(); + } + +// int test1_f() // WARNING HERE: "No return, in function returning non-void" +// { +// while (1) +// { +// } +// } + public void testNoRetInfinitLoop2() throws Exception { + // Bug 394521 + loadCodeAndRunCpp(getAboveComment()); + checkNoErrors(); + } } \ No newline at end of file