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A Java Optimization Framework
There is a newer version: 4.1.0
package soot.jimple.toolkits.scalar;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 2000 Patrick Lam
 * %%
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation, either version 2.1 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Lesser Public License for more details.
 * 
 * You should have received a copy of the GNU General Lesser Public
 * License along with this program.  If not, see
 * .
 * #L%
 */

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import soot.Body;
import soot.EquivalentValue;
import soot.Unit;
import soot.Value;
import soot.jimple.AssignStmt;
import soot.jimple.Stmt;
import soot.toolkits.graph.ExceptionalUnitGraph;
import soot.toolkits.scalar.FlowSet;
import soot.toolkits.scalar.UnitValueBoxPair;
import soot.util.Chain;
import soot.util.HashChain;

/**
 * Provides an user-interface for the AvailableExpressionsAnalysis class. Returns, for each statement, the list of
 * expressions available before and after it.
 */
public class SlowAvailableExpressions implements AvailableExpressions {
  Map> unitToPairsAfter;
  Map> unitToPairsBefore;

  Map> unitToEquivsAfter;
  Map> unitToEquivsBefore;

  /** Wrapper for SlowAvailableExpressionsAnalysis. */
  public SlowAvailableExpressions(Body b) {
    SlowAvailableExpressionsAnalysis analysis = new SlowAvailableExpressionsAnalysis(new ExceptionalUnitGraph(b));

    // Build unitToExprs map
    {
      unitToPairsAfter = new HashMap>(b.getUnits().size() * 2 + 1, 0.7f);
      unitToPairsBefore = new HashMap>(b.getUnits().size() * 2 + 1, 0.7f);
      unitToEquivsAfter = new HashMap>(b.getUnits().size() * 2 + 1, 0.7f);
      unitToEquivsBefore = new HashMap>(b.getUnits().size() * 2 + 1, 0.7f);

      for (Unit s : b.getUnits()) {
        FlowSet set = analysis.getFlowBefore(s);

        List pairsBefore = new ArrayList();
        List pairsAfter = new ArrayList();

        Chain equivsBefore = new HashChain();
        Chain equivsAfter = new HashChain();

        for (Value v : set) {
          Stmt containingStmt = analysis.rhsToContainingStmt.get(v);
          UnitValueBoxPair p = new UnitValueBoxPair(containingStmt, ((AssignStmt) containingStmt).getRightOpBox());
          EquivalentValue ev = new EquivalentValue(v);
          pairsBefore.add(p);
          if (!equivsBefore.contains(ev)) {
            equivsBefore.add(ev);
          }
        }

        unitToPairsBefore.put(s, pairsBefore);
        unitToEquivsBefore.put(s, equivsBefore);

        for (Value v : analysis.getFlowAfter(s)) {
          Stmt containingStmt = analysis.rhsToContainingStmt.get(v);
          UnitValueBoxPair p = new UnitValueBoxPair(containingStmt, ((AssignStmt) containingStmt).getRightOpBox());
          EquivalentValue ev = new EquivalentValue(v);
          pairsAfter.add(p);
          if (!equivsAfter.contains(ev)) {
            equivsAfter.add(ev);
          }
        }

        unitToPairsAfter.put(s, pairsAfter);
        unitToEquivsAfter.put(s, equivsAfter);
      }
    }
  }

  /** Returns a List containing the UnitValueBox pairs corresponding to expressions available before u. */
  public List getAvailablePairsBefore(Unit u) {
    return unitToPairsBefore.get(u);
  }

  /** Returns a List containing the UnitValueBox pairs corresponding to expressions available after u. */
  public List getAvailablePairsAfter(Unit u) {
    return unitToPairsAfter.get(u);
  }

  /** Returns a Chain containing the EquivalentValue objects corresponding to expressions available before u. */
  public Chain getAvailableEquivsBefore(Unit u) {
    return unitToEquivsBefore.get(u);
  }

  /** Returns a Chain containing the EquivalentValue objects corresponding to expressions available after u. */
  public Chain getAvailableEquivsAfter(Unit u) {
    return unitToEquivsAfter.get(u);
  }
}