Esempio n. 1
0
  /**
   * Look for a path in graph, from def to use. This path has to lie inside an extended basic block
   * (and this property implies uniqueness.). The path returned includes from and to.
   *
   * @param from start point for the path.
   * @param to end point for the path.
   * @return null if there is no such path.
   */
  public List getExtendedBasicBlockPathBetween(Unit from, Unit to) {
    UnitGraph g = this;

    // if this holds, we're doomed to failure!!!
    if (g.getPredsOf(to).size() > 1) return null;

    // pathStack := list of succs lists
    // pathStackIndex := last visited index in pathStack
    LinkedList pathStack = new LinkedList();
    LinkedList pathStackIndex = new LinkedList();

    pathStack.add(from);
    pathStackIndex.add(new Integer(0));

    int psiMax = (g.getSuccsOf((Unit) pathStack.get(0))).size();
    int level = 0;
    while (((Integer) pathStackIndex.get(0)).intValue() != psiMax) {
      int p = ((Integer) (pathStackIndex.get(level))).intValue();

      List succs = g.getSuccsOf((Unit) (pathStack.get(level)));
      if (p >= succs.size()) {
        // no more succs - backtrack to previous level.

        pathStack.remove(level);
        pathStackIndex.remove(level);

        level--;
        int q = ((Integer) pathStackIndex.get(level)).intValue();
        pathStackIndex.set(level, new Integer(q + 1));
        continue;
      }

      Unit betweenUnit = (Unit) (succs.get(p));

      // we win!
      if (betweenUnit == to) {
        pathStack.add(to);
        return pathStack;
      }

      // check preds of betweenUnit to see if we should visit its kids.
      if (g.getPredsOf(betweenUnit).size() > 1) {
        pathStackIndex.set(level, new Integer(p + 1));
        continue;
      }

      // visit kids of betweenUnit.
      level++;
      pathStackIndex.add(new Integer(0));
      pathStack.add(betweenUnit);
    }
    return null;
  }
  public StronglyConnectedComponentsBV(BitVector typeVariableList, TypeResolverBV resolver)
      throws TypeException {
    this.resolver = resolver;
    variables = typeVariableList;

    black = new TreeSet();
    finished = new LinkedList();

    for (BitSetIterator i = variables.iterator(); i.hasNext(); ) {
      TypeVariableBV var = resolver.typeVariableForId(i.next());

      if (!black.contains(var)) {
        black.add(var);
        dfsg_visit(var);
      }
    }

    black = new TreeSet();

    for (Iterator i = finished.iterator(); i.hasNext(); ) {
      TypeVariableBV var = (TypeVariableBV) i.next();

      if (!black.contains(var)) {
        current_tree = new LinkedList();
        forest.add(current_tree);
        black.add(var);
        dfsgt_visit(var);
      }
    }

    for (Iterator i = forest.iterator(); i.hasNext(); ) {
      LinkedList list = (LinkedList) i.next();
      TypeVariableBV previous = null;
      StringBuffer s = null;
      if (DEBUG) {
        s = new StringBuffer("scc:\n");
      }

      for (Iterator j = list.iterator(); j.hasNext(); ) {
        TypeVariableBV current = (TypeVariableBV) j.next();

        if (DEBUG) {
          s.append(" " + current + "\n");
        }

        if (previous == null) {
          previous = current;
        } else {
          try {
            previous = previous.union(current);
          } catch (TypeException e) {
            if (DEBUG) {
              G.v().out.println(s);
            }
            throw e;
          }
        }
      }
    }
  }
  private void dfsgt_visit(TypeVariableBV var) {
    current_tree.add(var);

    BitVector children = var.children();

    for (BitSetIterator i = children.iterator(); i.hasNext(); ) {
      TypeVariableBV child = resolver.typeVariableForId(i.next());

      if (!black.contains(child)) {
        black.add(child);
        dfsgt_visit(child);
      }
    }
  }
  private void dfsg_visit(TypeVariableBV var) {
    BitVector parents = var.parents();

    for (BitSetIterator i = parents.iterator(); i.hasNext(); ) {
      TypeVariableBV parent = resolver.typeVariableForId(i.next());

      if (!black.contains(parent)) {
        black.add(parent);
        dfsg_visit(parent);
      }
    }

    finished.add(0, var);
  }
Esempio n. 5
0
  private static boolean internalAggregate(
      StmtBody body, Map<ValueBox, Zone> boxToZone, boolean onlyStackVars) {
    LocalUses localUses;
    LocalDefs localDefs;
    ExceptionalUnitGraph graph;
    boolean hadAggregation = false;
    Chain<Unit> units = body.getUnits();

    graph = new ExceptionalUnitGraph(body);
    localDefs = new SmartLocalDefs(graph, new SimpleLiveLocals(graph));
    localUses = new SimpleLocalUses(graph, localDefs);

    List<Unit> unitList = new PseudoTopologicalOrderer<Unit>().newList(graph, false);
    for (Unit u : unitList) {
      if (!(u instanceof AssignStmt)) continue;
      AssignStmt s = (AssignStmt) u;

      Value lhs = s.getLeftOp();
      if (!(lhs instanceof Local)) continue;
      Local lhsLocal = (Local) lhs;

      if (onlyStackVars && !lhsLocal.getName().startsWith("$")) continue;

      List<UnitValueBoxPair> lu = localUses.getUsesOf(s);
      if (lu.size() != 1) continue;

      UnitValueBoxPair usepair = lu.get(0);
      Unit use = usepair.unit;
      ValueBox useBox = usepair.valueBox;

      List<Unit> ld = localDefs.getDefsOfAt(lhsLocal, use);
      if (ld.size() != 1) continue;

      // Check to make sure aggregation pair in the same zone
      if (boxToZone.get(s.getRightOpBox()) != boxToZone.get(usepair.valueBox)) {
        continue;
      }

      /* we need to check the path between def and use */
      /* to see if there are any intervening re-defs of RHS */
      /* in fact, we should check that this path is unique. */
      /* if the RHS uses only locals, then we know what
      to do; if RHS has a method invocation f(a, b,
      c) or field access, we must ban field writes, other method
      calls and (as usual) writes to a, b, c. */

      boolean cantAggr = false;
      boolean propagatingInvokeExpr = false;
      boolean propagatingFieldRef = false;
      boolean propagatingArrayRef = false;
      ArrayList<FieldRef> fieldRefList = new ArrayList<FieldRef>();

      LinkedList<Value> localsUsed = new LinkedList<Value>();
      for (ValueBox vb : s.getUseBoxes()) {
        Value v = vb.getValue();
        if (v instanceof Local) localsUsed.add(v);
        else if (v instanceof InvokeExpr) propagatingInvokeExpr = true;
        else if (v instanceof ArrayRef) propagatingArrayRef = true;
        else if (v instanceof FieldRef) {
          propagatingFieldRef = true;
          fieldRefList.add((FieldRef) v);
        }
      }

      // look for a path from s to use in graph.
      // only look in an extended basic block, though.

      List<Unit> path = graph.getExtendedBasicBlockPathBetween(s, use);

      if (path == null) continue;

      Iterator<Unit> pathIt = path.iterator();

      // skip s.
      if (pathIt.hasNext()) pathIt.next();

      while (pathIt.hasNext() && !cantAggr) {
        Stmt between = (Stmt) (pathIt.next());

        if (between != use) {
          // Check for killing definitions

          for (ValueBox vb : between.getDefBoxes()) {
            Value v = vb.getValue();
            if (localsUsed.contains(v)) {
              cantAggr = true;
              break;
            }

            if (propagatingInvokeExpr || propagatingFieldRef || propagatingArrayRef) {
              if (v instanceof FieldRef) {
                if (propagatingInvokeExpr) {
                  cantAggr = true;
                  break;
                } else if (propagatingFieldRef) {
                  // Can't aggregate a field access if passing a definition of a field
                  // with the same name, because they might be aliased
                  for (FieldRef fieldRef : fieldRefList) {
                    if (((FieldRef) v).getField() == fieldRef.getField()) {
                      cantAggr = true;
                      break;
                    }
                  }
                }
              } else if (v instanceof ArrayRef) {
                if (propagatingInvokeExpr) {
                  // Cannot aggregate an invoke expr past an array write
                  cantAggr = true;
                  break;
                } else if (propagatingArrayRef) {
                  // cannot aggregate an array read past a write
                  // this is somewhat conservative
                  // (if types differ they may not be aliased)

                  cantAggr = true;
                  break;
                }
              }
            }
          }

          // Make sure not propagating past a {enter,exit}Monitor
          if (propagatingInvokeExpr && between instanceof MonitorStmt) cantAggr = true;
        }

        // Check for intervening side effects due to method calls
        if (propagatingInvokeExpr || propagatingFieldRef || propagatingArrayRef) {
          for (final ValueBox box : between.getUseBoxes()) {
            if (between == use && box == useBox) {
              // Reached use point, stop looking for
              // side effects
              break;
            }

            Value v = box.getValue();

            if (v instanceof InvokeExpr
                || (propagatingInvokeExpr && (v instanceof FieldRef || v instanceof ArrayRef))) {
              cantAggr = true;
              break;
            }
          }
        }
      }

      // we give up: can't aggregate.
      if (cantAggr) {
        continue;
      }
      /* assuming that the d-u chains are correct, */
      /* we need not check the actual contents of ld */

      Value aggregatee = s.getRightOp();

      if (usepair.valueBox.canContainValue(aggregatee)) {
        boolean wasSimpleCopy = isSimpleCopy(usepair.unit);
        usepair.valueBox.setValue(aggregatee);
        units.remove(s);
        hadAggregation = true;
        // clean up the tags. If s was not a simple copy, the new statement should get
        // the tags of s.
        // OK, this fix was wrong. The condition should not be
        // "If s was not a simple copy", but rather "If usepair.unit
        // was a simple copy". This way, when there's a load of a constant
        // followed by an invoke, the invoke gets the tags.
        if (wasSimpleCopy) {
          // usepair.unit.removeAllTags();
          usepair.unit.addAllTagsOf(s);
        }
      } else {
        /*
        if(Options.v().verbose())
        {
            G.v().out.println("[debug] failed aggregation");
              G.v().out.println("[debug] tried to put "+aggregatee+
                             " into "+usepair.stmt +
                             ": in particular, "+usepair.valueBox);
              G.v().out.println("[debug] aggregatee instanceof Expr: "
                             +(aggregatee instanceof Expr));
        }*/
      }
    }
    return hadAggregation;
  }