/**
   * Traverse the statements in the given body, looking for aggregation possibilities; that is,
   * given a def d and a use u, d has no other uses, u has no other defs, collapse d and u.
   *
   * <p>option: only-stack-locals; if this is true, only aggregate variables starting with $
   */
  protected void internalTransform(Body b, String phaseName, Map<String, String> options) {
    StmtBody body = (StmtBody) b;
    boolean onlyStackVars = PhaseOptions.getBoolean(options, "only-stack-locals");

    int aggregateCount = 1;

    if (Options.v().time()) Timers.v().aggregationTimer.start();
    boolean changed = false;

    Map<ValueBox, Zone> boxToZone =
        new HashMap<ValueBox, Zone>(body.getUnits().size() * 2 + 1, 0.7f);

    // Determine the zone of every box
    {
      Zonation zonation = new Zonation(body);

      for (Unit u : body.getUnits()) {
        Zone zone = zonation.getZoneOf(u);

        for (ValueBox box : u.getUseBoxes()) {
          boxToZone.put(box, zone);
        }

        for (ValueBox box : u.getDefBoxes()) {
          boxToZone.put(box, zone);
        }
      }
    }

    do {
      if (Options.v().verbose())
        G.v()
            .out
            .println(
                "["
                    + body.getMethod().getName()
                    + "] Aggregating iteration "
                    + aggregateCount
                    + "...");

      // body.printTo(new java.io.PrintWriter(G.v().out, true));

      changed = internalAggregate(body, boxToZone, onlyStackVars);

      aggregateCount++;
    } while (changed);

    if (Options.v().time()) Timers.v().aggregationTimer.end();
  }
  public FaintVariableAnalysis(Body body) {

    Chain<Local> locals = body.getLocals();

    allVariables = new CollectionFlowUniverse<Local>(locals);

    universalSet = new ArrayPackedSet(allVariables);

    for (Local l : locals) universalSet.add(l);

    useSetMap = new HashMap<Unit, BoundedFlowSet>();
    defSetMap = new HashMap<Unit, BoundedFlowSet>();

    UnitGraph graph = new BriefUnitGraph(body);
    for (Unit u : graph) {

      BoundedFlowSet defSet = new ArrayPackedSet(allVariables);
      BoundedFlowSet useSet = new ArrayPackedSet(allVariables);

      for (ValueBox v : u.getDefBoxes()) {
        // Only do this for locals. We're not going to even try to handle anything
        // other than locals.
        if (v.getValue() instanceof Local) {
          defSet.add(v.getValue());
        }
      }
      for (ValueBox v : u.getUseBoxes()) {
        // Only do this for locals. We're not going to even try to handle anything
        // other than locals.
        if (v.getValue() instanceof Local) {
          useSet.add(v.getValue());
        }
      }

      defSetMap.put(u, defSet);
      useSetMap.put(u, useSet);
    }
  }