Commit f02c0088 authored by Carlos Galindo's avatar Carlos Galindo
Browse files

Support for the PPDG (building only)

parent 65be4201

src/main/java/tfm/exec/Config.java

+11 −7
Original line number Diff line number Diff line
@@ -5,20 +5,24 @@ package tfm.exec; 
 * <br/>

 * The <b>Control Flow Graph</b> has different variations, each with its own name or code.

 * <ul>

 *     <li>CFG</li>: the original proposal. It works well with statements, loops and branch instructions.

 *     <li>ACFG</li>: the <it>augmented</it> CFG; adds non-executable edges to represent unconditional

 *     jumps such as {@code break}, {@code return}, {@code switch} and much more.

 *     <li><b>CFG</b>: the original proposal. It works well with statements, loops and branch instructions.</li>

 *     <li><b>ACFG</b>: the <it>augmented</it> CFG; adds non-executable edges to represent unconditional

 *     jumps such as {@code break}, {@code return}, {@code switch} and much more.</li>

 * </ul>

 * The <b>Program Dependence Graph</b> has variations in a similar fashion.

 * <ul>

 *     <li>PDG</li>: based on the CFG, it computes control and data dependence to connect the nodes.

 *     <li>APDG</li>: similar to the PDG, but based on the ACFG. The non-executable edges are ignored

 *     when computing data dependencies.

 *     <li><b>PDG</b>: based on the CFG, it computes control and data dependence to connect the nodes.</li>

 *     <li><b>APDG</b>: similar to the PDG, but based on the ACFG. The non-executable edges are ignored

 *     when computing data dependencies.</li>

 *     <li><b>PPDG</b>: combines the PDG and the APDG; (1) when computing control dependencies it uses the ACFG

 *     to find a node's successors, but the CFG for computing the postdominance, and (2) modifies the traversal

 *     of the graph, disallowing the traversal of edges that reach a pseudo-predicate (those that are the source

 *     of non-executable edges) if the pseudo-predicate is not the slicing criterion.</li>

 * </ul>

 */

public class Config {

    public static final int CFG = 0, ACFG = 1;

    public static final int PDG = 0, APDG = 1;

    public static final int PDG = 0, APDG = 1, PPDG = 2;



    public static int CFG_TYPE = CFG;

    public static int PDG_TYPE = PDG;

src/main/java/tfm/graphs/PDGGraph.java

+0 −7
Original line number Diff line number Diff line
@@ -46,13 +46,6 @@ public class PDGGraph extends Graph { 
        return "Entry";

    }



    public GraphNode<?> addNode(GraphNode<?> node) {

        GraphNode<?> vertex = new GraphNode<>(node);

        super.addVertex(vertex);



        return vertex;

    }



    @Override

    public <ASTNode extends Node> GraphNode<ASTNode> addNode(String instruction, ASTNode node) {

        return addNode(getNextVertexId(), instruction, node);

src/main/java/tfm/visitors/pdg/ControlDependencyBuilder.java

+6 −1
Original line number Diff line number Diff line
@@ -2,11 +2,13 @@ package tfm.visitors.pdg; 


import tfm.arcs.Arc;

import tfm.arcs.data.ArcData;

import tfm.exec.Config;

import tfm.graphs.CFGGraph;

import tfm.graphs.PDGGraph;

import tfm.nodes.GraphNode;



import java.util.*;

import java.util.stream.Collectors;



/**

 * A simple but slow finder of control dependencies.
@@ -65,7 +67,7 @@ public class ControlDependencyBuilder { 
            return;

        GraphNode<?> clone = new GraphNode<>(node.getId(), node.getData(), node.getAstNode());

        nodeMap.put(node, clone);

        pdg.addNode(clone);

        pdg.addVertex(clone);

    }



    public static boolean hasControlDependence(GraphNode<?> a, GraphNode<?> b) {
@@ -92,6 +94,9 @@ public class ControlDependencyBuilder { 
        if (a.equals(b) || visited.contains(a))

            return true;

        List<Arc<ArcData>> outgoing = a.getOutgoingArcs();

        // Limit the traversal if it is a PPDG

        if (Config.PDG_TYPE == Config.PPDG)

            outgoing = outgoing.stream().filter(Arc::isExecutableControlFlowArrow).collect(Collectors.toList());

        // Stop w/ failure if there are no edges to traverse from a

        if (outgoing.size() == 0)

            return false;