soot.jimple.toolkits.thread.synchronization.LockAllocationBodyTransformer Maven / Gradle / Ivy

package soot.jimple.toolkits.thread.synchronization;

/*-
 * #%L
 * Soot - a J*va Optimization Framework
 * %%
 * Copyright (C) 1997 - 2018 Raja Vallée-Rai and others
 * %%
 * 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.Collections;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import soot.Body;
import soot.BodyTransformer;
import soot.EquivalentValue;
import soot.Local;
import soot.Modifier;
import soot.PatchingChain;
import soot.RefType;
import soot.Scene;
import soot.SootClass;
import soot.SootField;
import soot.SootMethod;
import soot.Trap;
import soot.Unit;
import soot.Value;
import soot.VoidType;
import soot.jimple.ArrayRef;
import soot.jimple.FieldRef;
import soot.jimple.InstanceFieldRef;
import soot.jimple.InstanceInvokeExpr;
import soot.jimple.Jimple;
import soot.jimple.JimpleBody;
import soot.jimple.Ref;
import soot.jimple.StaticFieldRef;
import soot.jimple.Stmt;
import soot.jimple.toolkits.infoflow.FakeJimpleLocal;
import soot.toolkits.scalar.FlowSet;
import soot.toolkits.scalar.Pair;
import soot.util.Chain;

public class LockAllocationBodyTransformer extends BodyTransformer {
  private static final Logger logger = LoggerFactory.getLogger(LockAllocationBodyTransformer.class);
  private static final LockAllocationBodyTransformer instance = new LockAllocationBodyTransformer();

  private LockAllocationBodyTransformer() {
  }

  public static LockAllocationBodyTransformer v() {
    return instance;
  }

  private static boolean addedGlobalLockDefs = false;
  private static int throwableNum = 0; // doesn't matter if not reinitialized
  // to 0

  protected void internalTransform(Body b, String phase, Map opts) {
    throw new RuntimeException("Not Supported");
  }

  protected void internalTransform(Body b, FlowSet fs, List groups, boolean[] insertedGlobalLock) {
    //
    JimpleBody j = (JimpleBody) b;
    SootMethod thisMethod = b.getMethod();
    PatchingChain units = b.getUnits();
    Iterator unitIt = units.iterator();
    Unit firstUnit = j.getFirstNonIdentityStmt();
    Unit lastUnit = units.getLast();

    // Objects of synchronization, plus book keeping
    Local[] lockObj = new Local[groups.size()];
    boolean[] addedLocalLockObj = new boolean[groups.size()];
    SootField[] globalLockObj = new SootField[groups.size()];
    for (int i = 1; i < groups.size(); i++) {
      lockObj[i] = Jimple.v().newLocal("lockObj" + i, RefType.v("java.lang.Object"));
      addedLocalLockObj[i] = false;
      globalLockObj[i] = null;
    }

    // Add all global lock objects to the main class if not yet added.
    // Get references to them if they do already exist.
    for (int i = 1; i < groups.size(); i++) {
      CriticalSectionGroup tnGroup = groups.get(i);
      if (!tnGroup.useDynamicLock && !tnGroup.useLocksets) {
        if (!insertedGlobalLock[i]) {
          // Add globalLockObj field if possible...

          // Avoid name collision... if it's already there, then just
          // use it!
          try {
            globalLockObj[i] = Scene.v().getMainClass().getFieldByName("globalLockObj" + i);
            // field already exists
          } catch (RuntimeException re) {
            // field does not yet exist (or, as a pre-existing
            // error, there is more than one field by this name)
            globalLockObj[i] = Scene.v().makeSootField("globalLockObj" + i, RefType.v("java.lang.Object"),
                Modifier.STATIC | Modifier.PUBLIC);
            Scene.v().getMainClass().addField(globalLockObj[i]);
          }

          insertedGlobalLock[i] = true;
        } else {
          globalLockObj[i] = Scene.v().getMainClass().getFieldByName("globalLockObj" + i);
        }
      }
    }

    // If the current method is the clinit method of the main class, for
    // each global lock object,
    // add a local lock object and assign it a new object. Copy the new
    // local lock object into the global lock object for use by other fns.
    if (!addedGlobalLockDefs)// thisMethod.getSubSignature().equals("void
    // ()") &&
    // thisMethod.getDeclaringClass() ==
    // Scene.v().getMainClass())
    {
      // Either get or add the  method to the main class
      SootClass mainClass = Scene.v().getMainClass();
      SootMethod clinitMethod = null;
      JimpleBody clinitBody = null;
      Stmt firstStmt = null;
      boolean addingNewClinit = !mainClass.declaresMethod("void ()");
      if (addingNewClinit) {
        clinitMethod
            = Scene.v().makeSootMethod("", new ArrayList(), VoidType.v(), Modifier.PUBLIC | Modifier.STATIC);
        clinitBody = Jimple.v().newBody(clinitMethod);
        clinitMethod.setActiveBody(clinitBody);
        mainClass.addMethod(clinitMethod);
      } else {
        clinitMethod = mainClass.getMethod("void ()");
        clinitBody = (JimpleBody) clinitMethod.getActiveBody();
        firstStmt = clinitBody.getFirstNonIdentityStmt();
      }
      PatchingChain clinitUnits = clinitBody.getUnits();

      for (int i = 1; i < groups.size(); i++) {
        CriticalSectionGroup tnGroup = groups.get(i);
        // if( useGlobalLock[i - 1] )
        if (!tnGroup.useDynamicLock && !tnGroup.useLocksets) {
          // add local lock obj
          // addedLocalLockObj[i] = true;
          clinitBody.getLocals().add(lockObj[i]); // TODO: add name
          // conflict
          // avoidance code

          // assign new object to lock obj
          Stmt newStmt = Jimple.v().newAssignStmt(lockObj[i], Jimple.v().newNewExpr(RefType.v("java.lang.Object")));
          if (addingNewClinit) {
            clinitUnits.add(newStmt);
          } else {
            clinitUnits.insertBeforeNoRedirect(newStmt, firstStmt);
          }

          // initialize new object
          SootClass objectClass = Scene.v().loadClassAndSupport("java.lang.Object");
          RefType type = RefType.v(objectClass);
          SootMethod initMethod = objectClass.getMethod("void ()");
          Stmt initStmt = Jimple.v()
              .newInvokeStmt(Jimple.v().newSpecialInvokeExpr(lockObj[i], initMethod.makeRef(), Collections.EMPTY_LIST));
          if (addingNewClinit) {
            clinitUnits.add(initStmt);
          } else {
            clinitUnits.insertBeforeNoRedirect(initStmt, firstStmt);
          }

          // copy new object to global static lock object (for use by
          // other fns)
          Stmt assignStmt = Jimple.v().newAssignStmt(Jimple.v().newStaticFieldRef(globalLockObj[i].makeRef()), lockObj[i]);
          if (addingNewClinit) {
            clinitUnits.add(assignStmt);
          } else {
            clinitUnits.insertBeforeNoRedirect(assignStmt, firstStmt);
          }
        }
      }
      if (addingNewClinit) {
        clinitUnits.add(Jimple.v().newReturnVoidStmt());
      }
      addedGlobalLockDefs = true;
    }

    int tempNum = 1;
    // Iterate through all of the transactions in the current method
    Iterator fsIt = fs.iterator();
    Stmt newPrep = null;
    while (fsIt.hasNext()) {
      CriticalSection tn = ((SynchronizedRegionFlowPair) fsIt.next()).tn;
      if (tn.setNumber == -1) {
        continue; // this tn should be deleted... for now just skip it!
      }

      if (tn.wholeMethod) {
        thisMethod.setModifiers(thisMethod.getModifiers() & ~(Modifier.SYNCHRONIZED)); // remove
        // synchronized
        // modifier
        // for
        // this
        // method
      }

      Local clo = null; // depends on type of locking
      SynchronizedRegion csr = null; // current synchronized region
      int lockNum = 0;
      boolean moreLocks = true;
      while (moreLocks) {
        // If this method does not yet have a reference to the lock
        // object
        // needed for this transaction, then create one.
        if (tn.group.useDynamicLock) {
          Value lock = getLockFor((EquivalentValue) tn.lockObject); // adds
          // local
          // vars
          // and
          // global
          // objects
          // if
          // needed
          if (lock instanceof Ref) {
            if (lock instanceof InstanceFieldRef) {
              InstanceFieldRef ifr = (InstanceFieldRef) lock;
              if (ifr.getBase() instanceof FakeJimpleLocal) {
                lock = reconstruct(b, units, ifr, (tn.entermonitor != null ? tn.entermonitor : tn.beginning),
                    (tn.entermonitor != null));
              }
            }
            if (!b.getLocals().contains(lockObj[tn.setNumber])) {
              b.getLocals().add(lockObj[tn.setNumber]);
            }

            newPrep = Jimple.v().newAssignStmt(lockObj[tn.setNumber], lock);
            if (tn.wholeMethod) {
              units.insertBeforeNoRedirect(newPrep, firstUnit);
            } else {
              units.insertBefore(newPrep, tn.entermonitor);
            }
            clo = lockObj[tn.setNumber];
          } else if (lock instanceof Local) {
            clo = (Local) lock;
          } else {
            throw new RuntimeException("Unknown type of lock (" + lock + "): expected Ref or Local");
          }
          csr = tn;
          moreLocks = false;
        } else if (tn.group.useLocksets) {
          Value lock = getLockFor((EquivalentValue) tn.lockset.get(lockNum)); // adds
          // local
          // vars
          // and
          // global
          // objects
          // if
          // needed
          if (lock instanceof FieldRef) {
            if (lock instanceof InstanceFieldRef) {
              InstanceFieldRef ifr = (InstanceFieldRef) lock;
              if (ifr.getBase() instanceof FakeJimpleLocal) {
                lock = reconstruct(b, units, ifr, (tn.entermonitor != null ? tn.entermonitor : tn.beginning),
                    (tn.entermonitor != null));
              }
            }
            // add a local variable for this lock
            Local lockLocal = Jimple.v().newLocal("locksetObj" + tempNum, RefType.v("java.lang.Object"));
            tempNum++;
            b.getLocals().add(lockLocal);

            // make it refer to the right lock object
            newPrep = Jimple.v().newAssignStmt(lockLocal, lock);
            if (tn.entermonitor != null) {
              units.insertBefore(newPrep, tn.entermonitor);
            } else {
              units.insertBeforeNoRedirect(newPrep, tn.beginning);
            }

            // use it as the lock
            clo = lockLocal;
          } else if (lock instanceof Local) {
            clo = (Local) lock;
          } else {
            throw new RuntimeException("Unknown type of lock (" + lock + "): expected FieldRef or Local");
          }

          if (lockNum + 1 >= tn.lockset.size()) {
            moreLocks = false;
          } else {
            moreLocks = true;
          }

          if (lockNum > 0) {
            SynchronizedRegion nsr = new SynchronizedRegion();

            nsr.beginning = csr.beginning;
            for (Pair earlyEnd : csr.earlyEnds) {
              Stmt earlyExitmonitor = (Stmt) earlyEnd.getO2();
              nsr.earlyEnds.add(new Pair(earlyExitmonitor, null)); // 
            }
            nsr.last = csr.last; // last stmt before exception
            // handling
            if (csr.end != null) {
              Stmt endExitmonitor = csr.end.getO2();
              nsr.after = endExitmonitor;
            }

            csr = nsr;
          } else {
            csr = tn;
          }
        } else // global lock
        {
          if (!addedLocalLockObj[tn.setNumber]) {
            b.getLocals().add(lockObj[tn.setNumber]);
          }
          addedLocalLockObj[tn.setNumber] = true;
          newPrep = Jimple.v().newAssignStmt(lockObj[tn.setNumber],
              Jimple.v().newStaticFieldRef(globalLockObj[tn.setNumber].makeRef()));
          if (tn.wholeMethod) {
            units.insertBeforeNoRedirect(newPrep, firstUnit);
          } else {
            units.insertBefore(newPrep, tn.entermonitor);
          }
          clo = lockObj[tn.setNumber];
          csr = tn;
          moreLocks = false;
        }

        // Add synchronization code
        // For transactions from synchronized methods, use
        // synchronizeSingleEntrySingleExitBlock()
        // to add all necessary code (including ugly exception handling)
        // For transactions from synchronized blocks, simply replace the
        // monitorenter/monitorexit statements with new ones
        if (true) {
          // Remove old prep stmt
          if (csr.prepStmt != null) {
            // units.remove(clr.prepStmt); // seems to trigger bugs
            // in code generation?
          }

          // Reuse old entermonitor or insert new one, and insert prep
          Stmt newEntermonitor = Jimple.v().newEnterMonitorStmt(clo);
          if (csr.entermonitor != null) {
            units.insertBefore(newEntermonitor, csr.entermonitor);
            // redirectTraps(b, clr.entermonitor, newEntermonitor);
            // // EXPERIMENTAL
            units.remove(csr.entermonitor);
            csr.entermonitor = newEntermonitor;

            // units.insertBefore(newEntermonitor, newPrep); //
            // already inserted
            // clr.prepStmt = newPrep;
          } else {
            units.insertBeforeNoRedirect(newEntermonitor, csr.beginning);
            csr.entermonitor = newEntermonitor;

            // units.insertBefore(newEntermonitor, newPrep); //
            // already inserted
            // clr.prepStmt = newPrep;
          }

          // For each early end, reuse or insert exitmonitor stmt
          List> newEarlyEnds = new ArrayList>();
          for (Pair end : csr.earlyEnds) {
            Stmt earlyEnd = end.getO1();
            Stmt exitmonitor = end.getO2();

            Stmt newExitmonitor = Jimple.v().newExitMonitorStmt(clo);
            if (exitmonitor != null) {
              if (newPrep != null) {
                Stmt tmp = (Stmt) newPrep.clone();
                units.insertBefore(tmp, exitmonitor); // seems
                // to
                // avoid
                // code
                // generation
                // bugs?
              }
              units.insertBefore(newExitmonitor, exitmonitor);
              // redirectTraps(b, exitmonitor, newExitmonitor); //
              // EXPERIMENTAL
              units.remove(exitmonitor);
              newEarlyEnds.add(new Pair(earlyEnd, newExitmonitor));
            } else {
              if (newPrep != null) {
                Stmt tmp = (Stmt) newPrep.clone();
                units.insertBefore(tmp, earlyEnd);
              }
              units.insertBefore(newExitmonitor, earlyEnd);
              newEarlyEnds.add(new Pair(earlyEnd, newExitmonitor));
            }
          }
          csr.earlyEnds = newEarlyEnds;

          // If fallthrough end, reuse or insert goto and exit
          if (csr.after != null) {
            Stmt newExitmonitor = Jimple.v().newExitMonitorStmt(clo);
            if (csr.end != null) {
              Stmt exitmonitor = csr.end.getO2();

              if (newPrep != null) {
                Stmt tmp = (Stmt) newPrep.clone();
                units.insertBefore(tmp, exitmonitor);
              }
              units.insertBefore(newExitmonitor, exitmonitor);
              // redirectTraps(b, exitmonitor, newExitmonitor); //
              // EXPERIMENTAL
              units.remove(exitmonitor);
              csr.end = new Pair(csr.end.getO1(), newExitmonitor);
            } else {
              if (newPrep != null) {
                Stmt tmp = (Stmt) newPrep.clone();
                units.insertBefore(tmp, csr.after);
              }
              units.insertBefore(newExitmonitor, csr.after); // steal
              // jumps
              // to
              // end,
              // send
              // them
              // to
              // monitorexit
              Stmt newGotoStmt = Jimple.v().newGotoStmt(csr.after);
              units.insertBeforeNoRedirect(newGotoStmt, csr.after);
              csr.end = new Pair(newGotoStmt, newExitmonitor);
              csr.last = newGotoStmt;
            }
          }

          // If exceptional end, reuse it, else insert it and traps
          Stmt newExitmonitor = Jimple.v().newExitMonitorStmt(clo);
          if (csr.exceptionalEnd != null) {
            Stmt exitmonitor = csr.exceptionalEnd.getO2();

            if (newPrep != null) {
              Stmt tmp = (Stmt) newPrep.clone();
              units.insertBefore(tmp, exitmonitor);
            }
            units.insertBefore(newExitmonitor, exitmonitor);

            units.remove(exitmonitor);
            csr.exceptionalEnd = new Pair(csr.exceptionalEnd.getO1(), newExitmonitor);
          } else {
            // insert after the last end
            Stmt lastEnd = null; // last end stmt (not same as last
            // stmt)
            if (csr.end != null) {
              lastEnd = csr.end.getO1();
            } else {
              for (Pair earlyEnd : csr.earlyEnds) {
                Stmt end = (Stmt) earlyEnd.getO1();
                if (lastEnd == null || (units.contains(lastEnd) && units.contains(end) && units.follows(end, lastEnd))) {
                  lastEnd = end;
                }
              }
            }
            if (csr.last == null) {
              csr.last = lastEnd; // last stmt and last end are
            }
            // the same
            if (lastEnd == null) {
              throw new RuntimeException("Lock Region has no ends!  Where should we put the exception handling???");
            }

            // Add throwable
            Local throwableLocal
                = Jimple.v().newLocal("throwableLocal" + (throwableNum++), RefType.v("java.lang.Throwable"));
            b.getLocals().add(throwableLocal);
            // Add stmts
            Stmt newCatch = Jimple.v().newIdentityStmt(throwableLocal, Jimple.v().newCaughtExceptionRef());
            if (csr.last == null) {
              throw new RuntimeException("WHY IS clr.last NULL???");
            }
            if (newCatch == null) {
              throw new RuntimeException("WHY IS newCatch NULL???");
            }
            units.insertAfter(newCatch, csr.last);
            units.insertAfter(newExitmonitor, newCatch);
            Stmt newThrow = Jimple.v().newThrowStmt(throwableLocal);
            units.insertAfter(newThrow, newExitmonitor);
            // Add traps
            SootClass throwableClass = Scene.v().loadClassAndSupport("java.lang.Throwable");
            b.getTraps().addFirst(Jimple.v().newTrap(throwableClass, newExitmonitor, newThrow, newCatch));
            b.getTraps().addFirst(Jimple.v().newTrap(throwableClass, csr.beginning, lastEnd, newCatch));
            csr.exceptionalEnd = new Pair(newThrow, newExitmonitor);
          }
        }
        lockNum++;
      }

      // deal with waits and notifys
      {
        for (Unit uNotify : tn.notifys) {
          Stmt sNotify = (Stmt) uNotify;
          Stmt newNotify = Jimple.v()
              .newInvokeStmt(Jimple.v().newVirtualInvokeExpr(clo,
                  sNotify.getInvokeExpr().getMethodRef().declaringClass().getMethod("void notifyAll()").makeRef(),
                  Collections.EMPTY_LIST));
          if (newPrep != null) {
            Stmt tmp = (Stmt) newPrep.clone();
            units.insertBefore(tmp, sNotify);
            units.insertBefore(newNotify, tmp);
          } else {
            units.insertBefore(newNotify, sNotify);
          }

          redirectTraps(b, sNotify, newNotify);
          units.remove(sNotify);
        }

        // Replace base object of calls to wait with appropriate lockobj
        for (Unit uWait : tn.waits) {
          Stmt sWait = (Stmt) uWait;
          ((InstanceInvokeExpr) sWait.getInvokeExpr()).setBase(clo); // WHAT
          // IF
          // THIS
          // IS
          // THE
          // WRONG
          // LOCK
          // IN
          // A
          // PAIR
          // OF
          // NESTED
          // LOCKS???
          if (newPrep != null) {
            units.insertBefore((Stmt) newPrep.clone(), sWait);
          }
        }
      }
    }
  }

  static int baseLocalNum = 0;

  public InstanceFieldRef reconstruct(Body b, PatchingChain units, InstanceFieldRef lock, Stmt insertBefore,
      boolean redirect) {
    logger.debug("Reconstructing " + lock);

    if (!(lock.getBase() instanceof FakeJimpleLocal)) {
      logger.debug("  base is not a FakeJimpleLocal");
      return lock;
    }
    FakeJimpleLocal fakeBase = (FakeJimpleLocal) lock.getBase();

    if (!(fakeBase.getInfo() instanceof LockableReferenceAnalysis)) {
      throw new RuntimeException("InstanceFieldRef cannot be reconstructed due to missing LocksetAnalysis info: " + lock);
    }
    LockableReferenceAnalysis la = (LockableReferenceAnalysis) fakeBase.getInfo();

    EquivalentValue baseEqVal = la.baseFor(lock);
    if (baseEqVal == null) {
      throw new RuntimeException("InstanceFieldRef cannot be reconstructed due to lost base from Lockset");
    }
    Value base = baseEqVal.getValue();
    Local baseLocal;
    if (base instanceof InstanceFieldRef) {
      Value newBase = reconstruct(b, units, (InstanceFieldRef) base, insertBefore, redirect);
      baseLocal = Jimple.v().newLocal("baseLocal" + (baseLocalNum++), newBase.getType());
      b.getLocals().add(baseLocal);

      // make it equal to the right value
      Stmt baseAssign = Jimple.v().newAssignStmt(baseLocal, newBase);
      if (redirect == true) {
        units.insertBefore(baseAssign, insertBefore);
      } else {
        units.insertBeforeNoRedirect(baseAssign, insertBefore);
      }
    } else if (base instanceof Local) {
      baseLocal = (Local) base;
    } else {
      throw new RuntimeException("InstanceFieldRef cannot be reconstructed because it's base is of an unsupported type"
          + base.getType() + ": " + base);
    }

    InstanceFieldRef newLock = Jimple.v().newInstanceFieldRef(baseLocal, lock.getField().makeRef());
    logger.debug("  as " + newLock);
    return newLock;
  }

  static int lockNumber = 0;
  static Map lockEqValToLock = new HashMap();

  static public Value getLockFor(EquivalentValue lockEqVal) {
    Value lock = lockEqVal.getValue();

    if (lock instanceof InstanceFieldRef) {
      return lock;
    }

    if (lock instanceof ArrayRef) {
      // ref for each value of the index!
      return ((ArrayRef) lock).getBase();
    }

    if (lock instanceof Local) {
      return lock;
    }

    if (lock instanceof StaticFieldRef || lock instanceof NewStaticLock) {
      if (lockEqValToLock.containsKey(lockEqVal)) {
        return lockEqValToLock.get(lockEqVal);
      }

      SootClass lockClass = null;
      if (lock instanceof StaticFieldRef) {
        StaticFieldRef sfrLock = (StaticFieldRef) lock;
        lockClass = sfrLock.getField().getDeclaringClass();
      } else if (lock instanceof NewStaticLock) {
        DeadlockAvoidanceEdge dae = (DeadlockAvoidanceEdge) lock;
        lockClass = dae.getLockClass();
      }
      SootMethod clinitMethod = null;
      JimpleBody clinitBody = null;
      Stmt firstStmt = null;
      boolean addingNewClinit = !lockClass.declaresMethod("void ()");
      if (addingNewClinit) {
        clinitMethod
            = Scene.v().makeSootMethod("", new ArrayList(), VoidType.v(), Modifier.PUBLIC | Modifier.STATIC);
        clinitBody = Jimple.v().newBody(clinitMethod);
        clinitMethod.setActiveBody(clinitBody);
        lockClass.addMethod(clinitMethod);
      } else {
        clinitMethod = lockClass.getMethod("void ()");
        clinitBody = (JimpleBody) clinitMethod.getActiveBody();
        firstStmt = clinitBody.getFirstNonIdentityStmt();
      }
      PatchingChain clinitUnits = clinitBody.getUnits();

      Local lockLocal = Jimple.v().newLocal("objectLockLocal" + lockNumber, RefType.v("java.lang.Object"));
      // lockNumber is increased below
      clinitBody.getLocals().add(lockLocal); // TODO: add name conflict
      // avoidance code

      // assign new object to lock obj
      Stmt newStmt = Jimple.v().newAssignStmt(lockLocal, Jimple.v().newNewExpr(RefType.v("java.lang.Object")));
      if (addingNewClinit) {
        clinitUnits.add(newStmt);
      } else {
        clinitUnits.insertBeforeNoRedirect(newStmt, firstStmt);
      }

      // initialize new object
      SootClass objectClass = Scene.v().loadClassAndSupport("java.lang.Object");
      RefType type = RefType.v(objectClass);
      SootMethod initMethod = objectClass.getMethod("void ()");
      Stmt initStmt = Jimple.v()
          .newInvokeStmt(Jimple.v().newSpecialInvokeExpr(lockLocal, initMethod.makeRef(), Collections.EMPTY_LIST));
      if (addingNewClinit) {
        clinitUnits.add(initStmt);
      } else {
        clinitUnits.insertBeforeNoRedirect(initStmt, firstStmt);
      }

      // copy new object to global static lock object (for use by other
      // fns)
      SootField actualLockObject = Scene.v().makeSootField("objectLockGlobal" + lockNumber, RefType.v("java.lang.Object"),
          Modifier.STATIC | Modifier.PUBLIC);
      lockNumber++;
      lockClass.addField(actualLockObject);

      StaticFieldRef actualLockSfr = Jimple.v().newStaticFieldRef(actualLockObject.makeRef());
      Stmt assignStmt = Jimple.v().newAssignStmt(actualLockSfr, lockLocal);
      if (addingNewClinit) {
        clinitUnits.add(assignStmt);
      } else {
        clinitUnits.insertBeforeNoRedirect(assignStmt, firstStmt);
      }

      if (addingNewClinit) {
        clinitUnits.add(Jimple.v().newReturnVoidStmt());
      }

      lockEqValToLock.put(lockEqVal, actualLockSfr);
      return actualLockSfr;
    }

    throw new RuntimeException("Unknown type of lock (" + lock + "): expected FieldRef, ArrayRef, or Local");
  }

  public void redirectTraps(Body b, Unit oldUnit, Unit newUnit) {
    Chain traps = b.getTraps();
    for (Trap trap : traps) {
      if (trap.getHandlerUnit() == oldUnit) {
        trap.setHandlerUnit(newUnit);
      }
      if (trap.getBeginUnit() == oldUnit) {
        trap.setBeginUnit(newUnit);
      }
      if (trap.getEndUnit() == oldUnit) {
        trap.setEndUnit(newUnit);
      }
    }
  }

}