Package soot.toolkits.graph

Examples of soot.toolkits.graph.DominatorTree


   */
  @SuppressWarnings("unchecked")
  protected void constructPDG()
  {
    Hashtable<Block, Region> block2region = this.m_regionAnalysis.getBlock2RegionMap();
    DominatorTree pdom = this.m_regionAnalysis.getPostDominatorTree();
    DominatorTree dom = this.m_regionAnalysis.getDominatorTree();
       
    List<Region> regions2process = new LinkedList<Region>();
    Region topLevelRegion = this.m_regionAnalysis.getTopLevelRegion();
    m_strongRegionStartID = m_weakRegions.size();
   
    //This becomes the top-level region (or ENTRY region node)
    PDGNode pdgnode = new PDGNode(topLevelRegion, PDGNode.Type.REGION);
    this.addNode(pdgnode);
    this.m_obj2pdgNode.put(topLevelRegion, pdgnode);
    this.m_startNode = pdgnode;
    topLevelRegion.setParent(null);
   
    regions2process.add(topLevelRegion);
   
    //while there's a (weak) region to process
    while(!regions2process.isEmpty())
    {
      Region r = regions2process.remove(0);
     
      //get the corresponding pdgnode
      pdgnode = this.m_obj2pdgNode.get(r);
     
      /*
       * For all the CFG nodes in the region, create the corresponding PDG node and edges, and
       * process them if they are in the dependence set of other regions, i.e. other regions
       * depend on them.
       */
      List<Block> blocks = r.getBlocks();
      Hashtable<Region, List<Block>> toBeRemoved = new Hashtable<Region, List<Block>>();
      PDGNode prevPDGNodeInRegion = null;
      PDGNode curNodeInRegion = null;
      for(Iterator<Block> itr = blocks.iterator(); itr.hasNext();)
      {
        /*
         * Add the PDG node corresponding to the CFG block node.
         */
        Block a = itr.next();
        PDGNode pdgNodeOfA = null;
        if(!this.m_obj2pdgNode.containsKey(a))
        {
          pdgNodeOfA = new PDGNode(a, PDGNode.Type.CFGNODE);
          this.addNode(pdgNodeOfA);
          this.m_obj2pdgNode.put(a, pdgNodeOfA);
        }
        else
          pdgNodeOfA = this.m_obj2pdgNode.get(a);
               
        this.addEdge(pdgnode, pdgNodeOfA, "dependency");
        pdgnode.addDependent(pdgNodeOfA);
        //
       
        curNodeInRegion = pdgNodeOfA;
       
        /*
         * For each successor B of A, if B does not post-dominate A, add all the
         * nodes on the path from B to the L in the post-dominator tree, where L is the least
         * common ancestor of A and B in the post-dominator tree (L will be either A itself or
         * the parent of A.).
         */
       
        List<Block> bs = this.m_blockCFG.getSuccsOf(a);
        for(Iterator<Block> bItr = bs.iterator(); bItr.hasNext();)
        {
          List<Block> dependents = new ArrayList<Block>();
         
          Block b = bItr.next();
         
          if(b.equals(a))
            throw new RuntimeException("PDG construction: A and B are not supposed to be the same node!");
         
         
          DominatorNode aDode = pdom.getDode(a);
          DominatorNode bDode = pdom.getDode(b);
         
          //If B post-dominates A, go to the next successor.
          if(pdom.isDominatorOf(bDode, aDode))
            continue;
         
          //FIXME: what if the parent is null?!!
          DominatorNode aParentDode = aDode.getParent();
         
          DominatorNode dode = bDode;
          while(dode != aParentDode)
          {
            dependents.add((Block)dode.getGode());
           
            //This occurs if the CFG is multi-tailed and therefore the pdom is a forest.
            if(dode.getParent() == null)
              //throw new RuntimeException("parent dode in pdom is null: dode is " + aDode);
              break;
            dode = dode.getParent();           
          }
         
          /*
           * If node A is in the dependent list of A, then A is the header of a loop.
           * Otherwise, A could still be the header of a loop or just a simple predicate.
           */
         
          //first make A's pdg node be a conditional (predicate) pdgnode, if it's not already.         
          if(pdgNodeOfA.getAttrib() != PDGNode.Attribute.CONDHEADER)
          {
            PDGNode oldA = pdgNodeOfA;
            pdgNodeOfA = new ConditionalPDGNode(pdgNodeOfA);
            this.replaceInGraph(pdgNodeOfA, oldA);
            pdgnode.removeDependent(oldA);
            this.m_obj2pdgNode.put(a, pdgNodeOfA);
            pdgnode.addDependent(pdgNodeOfA);
            pdgNodeOfA.setAttrib(PDGNode.Attribute.CONDHEADER);
           
            curNodeInRegion = pdgNodeOfA;
          }   
         
          List<Block> copyOfDependents = new ArrayList<Block>();
          copyOfDependents.addAll(dependents);
         
          //First, add the dependency for B and its corresponding region.
          Region regionOfB = block2region.get(b);
          PDGNode pdgnodeOfBRegion = null;
          if(!this.m_obj2pdgNode.containsKey(regionOfB))
          {
            pdgnodeOfBRegion = new PDGNode(regionOfB, PDGNode.Type.REGION);
            this.addNode(pdgnodeOfBRegion);
            this.m_obj2pdgNode.put(regionOfB, pdgnodeOfBRegion);
           
          }
          else
            pdgnodeOfBRegion = this.m_obj2pdgNode.get(regionOfB);
         
          //set the region hierarchy
          regionOfB.setParent(r);
          r.addChildRegion(regionOfB);
         
          //add the dependency edges
          this.addEdge(pdgNodeOfA, pdgnodeOfBRegion, "dependency");
          pdgNodeOfA.addDependent(pdgnodeOfBRegion);
          regions2process.add(regionOfB);
          //now remove b and all the nodes in the same weak region from the list of dependents
          copyOfDependents.remove(b);
          copyOfDependents.removeAll(regionOfB.getBlocks());
       
         
          /* What remains here in the dependence set needs to be processed separately. For
           * each node X remained in the dependency set, find the corresponding PDG region node
           * and add a dependency edge from the region of B to the region of X. If X's weak
           * region contains other nodes not in the dependency set of A, create a new region
           * for X and add the proper dependency edges (this actually happens if X is the header
           * of a loop and B is a predicate guarding a break/continue.)
           *
           * Note: it seems the only case that there is a node remained in the dependents is when there
           * is a path from b to the header of a loop.
           */
         
          while(!copyOfDependents.isEmpty())
          {
            Block depB = copyOfDependents.remove(0);
            Region rdepB = block2region.get(depB);
           
            /*
             * Actually, there are cases when depB is not the header of a loop and therefore would not dominate the current node
             * (A) and therefore might not have been created yet. This has happened when an inner loop breaks out of the outer
             * loop but could have other cases too.
             */
            PDGNode depBPDGNode = this.m_obj2pdgNode.get(depB);
            if(depBPDGNode == null)
            {           
              //First, add the dependency for depB and its corresponding region.
             
              PDGNode pdgnodeOfdepBRegion = null;
              if(!this.m_obj2pdgNode.containsKey(rdepB))
              {
                pdgnodeOfdepBRegion = new PDGNode(rdepB, PDGNode.Type.REGION);
                this.addNode(pdgnodeOfdepBRegion);
                this.m_obj2pdgNode.put(rdepB, pdgnodeOfdepBRegion);
               
              }
              else
                pdgnodeOfdepBRegion = this.m_obj2pdgNode.get(rdepB);
             
              //set the region hierarchy
              rdepB.setParent(regionOfB);
              regionOfB.addChildRegion(rdepB);
             
              //add the dependency edges
              this.addEdge(pdgnodeOfBRegion, pdgnodeOfdepBRegion, "dependency");
              pdgnodeOfBRegion.addDependent(pdgnodeOfdepBRegion);
              regions2process.add(rdepB);
             
              //now remove all the nodes in the same weak region from the list of dependents
             
              copyOfDependents.removeAll(rdepB.getBlocks());
             
              continue;

            }
           
            /**
             * If all the nodes in the weak region of depB are dependent on A, then add
             * an edge from the region of B to the region of depB.
             *
             * else, a new region has to be created to contain the dependences of depB, if
             * not already created.
             */
            if(dependents.containsAll(rdepB.getBlocks()))
            {
              /*
               * Just add an edge to the pdg node of the existing depB region.
               *
               */
              //add the dependency edges
              //First, add the dependency for depB and its corresponding region.
             
              PDGNode pdgnodeOfdepBRegion = null;
              if(!this.m_obj2pdgNode.containsKey(rdepB))
              {
                pdgnodeOfdepBRegion = new PDGNode(rdepB, PDGNode.Type.REGION);
                this.addNode(pdgnodeOfdepBRegion);
                this.m_obj2pdgNode.put(rdepB, pdgnodeOfdepBRegion);
               
              }
              else
                pdgnodeOfdepBRegion = this.m_obj2pdgNode.get(rdepB);
             
              //set the region hierarchy
              //Do not set this because the region was created before so must have the
              //proper parent already.
              //rdepB.setParent(regionOfB);
              //regionOfB.addChildRegion(rdepB);
             
              this.addEdge(pdgnodeOfBRegion, pdgnodeOfdepBRegion, "dependency");
              pdgnodeOfBRegion.addDependent(pdgnodeOfdepBRegion);
              regions2process.add(rdepB);
             
              //now remove all the nodes in the same weak region from the list of dependents
             
              copyOfDependents.removeAll(rdepB.getBlocks());
 
              continue;
            }
            else
            {
              PDGNode predPDGofdepB = (PDGNode) this.getPredsOf(depBPDGNode).get(0);
              assert(this.m_obj2pdgNode.containsKey(rdepB));             
              PDGNode pdgnodeOfdepBRegion = this.m_obj2pdgNode.get(rdepB);
              //If the loop header has not been separated from its weak region yet
              if(predPDGofdepB == pdgnodeOfdepBRegion)
              {
                /*
                 * Create a new region to represent the whole loop. In fact, this is a strong
                 * region as opposed to the weak regions that were created in the RegionAnalysis.
                 * This strong region only contains the header of the loop, A, and is dependent
                 * on it. Also, A is dependent on this strong region as well.
                 */
               
                Region newRegion = new Region(this.m_strongRegionStartID++, topLevelRegion.getSootMethod(), topLevelRegion.getSootClass(), this.m_cfg);
                newRegion.add(depB);
               
                this.m_strongRegions.add(newRegion);
                               
                //toBeRemoved.add(depB);
                List<Block> blocks2BRemoved;
                if(toBeRemoved.contains(predPDGofdepB))
                  blocks2BRemoved = toBeRemoved.get(predPDGofdepB);
                else
                {
                  blocks2BRemoved = new ArrayList<Block>();
                  toBeRemoved.put(rdepB, blocks2BRemoved);
                }
                blocks2BRemoved.add(depB);
               
               
               
                PDGNode newpdgnode = new LoopedPDGNode(newRegion, PDGNode.Type.REGION, depBPDGNode);
                this.addNode(newpdgnode);
                this.m_obj2pdgNode.put(newRegion, newpdgnode);
                newpdgnode.setAttrib(PDGNode.Attribute.LOOPHEADER);
                depBPDGNode.setAttrib(PDGNode.Attribute.LOOPHEADER);
               
                this.removeEdge(pdgnodeOfdepBRegion, depBPDGNode, "dependency");
                pdgnodeOfdepBRegion.removeDependent(depBPDGNode);
                this.addEdge(pdgnodeOfdepBRegion, newpdgnode, "dependency");
                this.addEdge(newpdgnode, depBPDGNode, "dependency");
                pdgnodeOfdepBRegion.addDependent(newpdgnode);
                newpdgnode.addDependent(depBPDGNode);
               
               
               
                //If a is dependent on itself (simple loop)
                if(depB == a)
                {
                  PDGNode loopBodyPDGNode = (PDGNode) this.getSuccsOf(depBPDGNode).get(0);
                  this.addEdge(depBPDGNode, newpdgnode, "dependency-back");
                  ((LoopedPDGNode)newpdgnode).setBody(loopBodyPDGNode);
                 
                  depBPDGNode.addBackDependent(newpdgnode);
                 
                  //This is needed to correctly adjust the prev/next pointers for the new loop node. We should not need
                  //to adjust the old loop header node because the prev/next should not have been set previously for it.
                  curNodeInRegion = newpdgnode;
                 
                }
                else
                {
                 
                  //this is a back-dependency
                  pdgnodeOfBRegion.addBackDependent(newpdgnode);
                  this.addEdge(pdgnodeOfBRegion, newpdgnode, "dependency-back");
                 
                  //DEtermine which dependent of the loop header is actually the loop body region
                  PDGNode loopBodyPDGNode = null;
                  List<PDGNode> successors = this.getSuccsOf(depBPDGNode);
                  Iterator<PDGNode> succItr = successors.iterator();
                  while(succItr.hasNext())
                  {
                    PDGNode succRPDGNode = succItr.next();
                   
                    assert(succRPDGNode.getType() == PDGNode.Type.REGION);
                    Region succR = (Region) succRPDGNode.getNode();
                    Block h = succR.getBlocks().get(0);
                   
                    DominatorNode hdode = dom.getDode(h);
                    DominatorNode adode = dom.getDode(a);
                   
                    if(dom.isDominatorOf(hdode, adode))
                    {
                      loopBodyPDGNode = succRPDGNode;
                      break;
                    }
                   
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