TAPAS-2020: implementation of the algorithm proposed (3c771a29) · Commits · Program Slicing / SDG

sdg-cli/src/main/java/es/upv/mist/slicing/cli/Slicer.java

+6 −4

Original line number	Diff line number	Diff line
		@@ -11,6 +11,7 @@ import com.github.javaparser.symbolsolver.resolution.typesolvers.JavaParserTypeS
		import com.github.javaparser.symbolsolver.resolution.typesolvers.ReflectionTypeSolver;
		import es.upv.mist.slicing.graphs.augmented.ASDG;
		import es.upv.mist.slicing.graphs.augmented.PSDG;
		import es.upv.mist.slicing.graphs.augmented.TapasSDG;
		import es.upv.mist.slicing.graphs.exceptionsensitive.ESSDG;
		import es.upv.mist.slicing.graphs.sdg.SDG;
		import es.upv.mist.slicing.slicing.FileLineSlicingCriterion;
		@@ -236,6 +237,7 @@ public class Slicer {
		case "ASDG": sdg = new ASDG(); break;
		case "PSDG": sdg = new PSDG(); break;
		case "ESSDG": sdg = new ESSDG(); break;
		case "TSDG": sdg = new TapasSDG(); break;
		default:
		throw new IllegalArgumentException("Unknown type of graph. Available graphs are SDG, ASDG, PSDG, ESSDG");
		}

sdg-core/src/main/java/es/upv/mist/slicing/graphs/augmented/ACFGBuilder.java

+4 −2

Original line number	Diff line number	Diff line
		@@ -69,12 +69,13 @@ public class ACFGBuilder extends CFGBuilder {
		// Link previous statement to the switch's selector
		switchEntriesStack.push(new LinkedList<>());
		breakStack.push(new LinkedList<>());
		GraphNode<?> cond = connectTo(switchStmt, String.format("switch (%s)", switchStmt.getSelector()));
		GraphNode<SwitchStmt> cond = connectTo(switchStmt, String.format("switch (%s)", switchStmt.getSelector()));
		hangingNodes.remove(cond);
		switchStack.push(cond);
		switchStmt.getSelector().accept(this, arg);
		// expr --> each case (fallthrough by default, so case --> case too)
		for (SwitchEntryStmt entry : switchStmt.getEntries()) {
		entry.accept(this, arg); // expr && prev case --> case --> next case
		hangingNodes.add(cond); // expr --> next case
		}
		// The next statement will be linked to:
		// 1. All break statements that broke from the switch (done with break section)
		@@ -84,6 +85,7 @@ public class ACFGBuilder extends CFGBuilder {
		if (ASTUtils.switchHasDefaultCase(switchStmt))
		hangingNodes.remove(cond);
		List<GraphNode<SwitchEntryStmt>> entries = switchEntriesStack.pop();
		switchStack.pop();
		GraphNode<SwitchEntryStmt> def = null;
		for (GraphNode<SwitchEntryStmt> entry : entries) {
		if (entry.getAstNode().getLabel().isEmpty()) {

sdg-core/src/main/java/es/upv/mist/slicing/graphs/augmented/TapasPDG.java

0 → 100644

+70 −0

Original line number	Diff line number	Diff line
		package es.upv.mist.slicing.graphs.augmented;

		import es.upv.mist.slicing.arcs.Arc;
		import es.upv.mist.slicing.arcs.pdg.ControlDependencyArc;
		import es.upv.mist.slicing.nodes.GraphNode;

		import java.util.HashSet;
		import java.util.Set;
		import java.util.stream.Collectors;

		/**
		* An alternative program dependence graph to the {@link PPDG}, which
		* performs the same optimization without altering the slicing algorithm,
		* thus guaranteeing that it's kept ats its original linear time complexity.
		*/
		public class TapasPDG extends APDG {
		public TapasPDG() {
		super();
		}

		public TapasPDG(ACFG acfg) {
		super(acfg);
		}

		@Override
		protected Builder createBuilder() {
		return new Builder();
		}

		public class Builder extends APDG.Builder {
		@Override
		protected void buildControlDependency() {
		super.buildControlDependency();
		algorithm1();
		}

		/** Removes all incoming edges of a pseudo-predicate, when (1) there is a control
		* dependency between itself and another pseudo-predicate, and (2) both jump to
		* the same instruction. */
		protected void algorithm1() {
		Set<ControlDependencyArc> Ac = edgeSet().stream()
		.filter(Arc::isControlDependencyArc)
		.map(ControlDependencyArc.class::cast)
		.collect(Collectors.toSet());
		Set<Arc> arcsToRemove = new HashSet<>();
		for (ControlDependencyArc arc : Ac) {
		GraphNode<?> ns = getEdgeSource(arc);
		GraphNode<?> ne = getEdgeTarget(arc);
		ACFG acfg = (ACFG) cfg;
		if (acfg.isPseudoPredicate(ns) && acfg.isPseudoPredicate(ne) && jumpDest(ns).equals(jumpDest(ne))) {
		edgeSet().stream()
		.filter(Arc::isControlDependencyArc)
		.filter(a -> getEdgeTarget(a).equals(ne))
		.forEach(arcsToRemove::add);
		}
		}
		arcsToRemove.forEach(TapasPDG.this::removeEdge);
		}

		/** Obtain the target of a jump instruction. In the CFG, it should
		* have just one executable outgoing edge. */
		protected GraphNode<?> jumpDest(GraphNode<?> jumpNode) {
		Set<Arc> outgoing = new HashSet<>(cfg.outgoingEdgesOf(jumpNode));
		outgoing.removeIf(Arc::isNonExecutableControlFlowArc);
		if (outgoing.size() != 1)
		throw new IllegalArgumentException("Jump has 0 or multiple executable outgoing edges.");
		return cfg.getEdgeTarget(outgoing.iterator().next());
		}
		}
		}

sdg-core/src/main/java/es/upv/mist/slicing/graphs/augmented/TapasSDG.java

0 → 100644

+19 −0

Original line number	Diff line number	Diff line
		package es.upv.mist.slicing.graphs.augmented;

		import es.upv.mist.slicing.graphs.cfg.CFG;
		import es.upv.mist.slicing.graphs.pdg.PDG;

		public class TapasSDG extends ASDG {
		@Override
		protected Builder createBuilder() {
		return new Builder();
		}

		public class Builder extends ASDG.Builder {
		@Override
		protected PDG createPDG(CFG cfg) {
		assert cfg instanceof ACFG;
		return new TapasPDG((ACFG) cfg);
		}
		}
		}

sdg-core/src/main/java/es/upv/mist/slicing/graphs/cfg/CFGBuilder.java

+11 −5

Original line number	Diff line number	Diff line
		@@ -55,6 +55,8 @@ public class CFGBuilder extends VoidVisitorAdapter<Void> {
		protected final Map<SimpleName, List<GraphNode<ContinueStmt>>> continueMap = new HashMap<>();
		/** Return statements that should be connected to the final node, if it is created at the end of the */
		protected final List<GraphNode<ReturnStmt>> returnList = new LinkedList<>();
		/** Stack of switch statements. */
		protected final Deque<GraphNode<SwitchStmt>> switchStack = new LinkedList<>();
		/** Stack of lists of hanging cases on switch statements */
		protected final Deque<List<GraphNode<SwitchEntryStmt>>> switchEntriesStack = new LinkedList<>();

		@@ -271,8 +273,10 @@ public class CFGBuilder extends VoidVisitorAdapter<Void> {
		@Override
		public void visit(SwitchEntryStmt entryStmt, Void arg) {
		// Case header (prev -> case EXPR)
		GraphNode<SwitchEntryStmt> node = connectTo(entryStmt, entryStmt.getLabel().isPresent() ?
		"case " + entryStmt.getLabel().get() : "default");
		GraphNode<SwitchEntryStmt> node = graph.addVertex(entryStmt.getLabel().isPresent() ?
		"case " + entryStmt.getLabel().get() : "default", entryStmt);
		graph.addControlFlowArc(switchStack.element(), node);
		hangingNodes.add(node);
		switchEntriesStack.peek().add(node);
		// Case body (case EXPR --> body)
		entryStmt.getStatements().accept(this, arg);
		@@ -284,12 +288,13 @@ public class CFGBuilder extends VoidVisitorAdapter<Void> {
		// Link previous statement to the switch's selector
		switchEntriesStack.push(new LinkedList<>());
		breakStack.push(new LinkedList<>());
		GraphNode<?> cond = connectTo(switchStmt, String.format("switch (%s)", switchStmt.getSelector()));
		GraphNode<SwitchStmt> cond = connectTo(switchStmt, String.format("switch (%s)", switchStmt.getSelector()));
		hangingNodes.remove(cond);
		switchStack.push(cond);
		switchStmt.getSelector().accept(this, arg);
		// expr --> each case (fallthrough by default, so case --> case too)
		for (SwitchEntryStmt entry : switchStmt.getEntries()) {
		entry.accept(this, arg); // expr && prev case --> case --> next case
		hangingNodes.add(cond); // expr --> next case
		}
		// The next statement will be linked to:
		// 1. All break statements that broke from the switch (done with break section)
		@@ -298,7 +303,8 @@ public class CFGBuilder extends VoidVisitorAdapter<Void> {
		// If the last case is a default case, remove the selector node from the list of nodes (see 2)
		if (ASTUtils.switchHasDefaultCase(switchStmt))
		hangingNodes.remove(cond);
		List<GraphNode<SwitchEntryStmt>> entries = switchEntriesStack.pop();
		switchEntriesStack.pop();
		switchStack.pop();
		// End block and break section
		hangingNodes.addAll(breakStack.pop());
		}