bug fix
[IRC.git] / Robust / src / Analysis / SSJava / DefinitelyWrittenCheck.java
index dc2881d5786f1ff722b8c25c6ed99be2d4ea4ade..2536171de0ec1049f11cba86a0988f63991ca57f 100644 (file)
@@ -8,6 +8,7 @@ import java.util.Set;
 import java.util.Stack;
 
 import Analysis.CallGraph.CallGraph;
+import Analysis.Loops.LoopFinder;
 import IR.Descriptor;
 import IR.FieldDescriptor;
 import IR.MethodDescriptor;
@@ -16,821 +17,1607 @@ import IR.State;
 import IR.TypeDescriptor;
 import IR.Flat.FKind;
 import IR.Flat.FlatCall;
+import IR.Flat.FlatElementNode;
 import IR.Flat.FlatFieldNode;
 import IR.Flat.FlatLiteralNode;
 import IR.Flat.FlatMethod;
 import IR.Flat.FlatNode;
 import IR.Flat.FlatOpNode;
+import IR.Flat.FlatSetElementNode;
 import IR.Flat.FlatSetFieldNode;
 import IR.Flat.TempDescriptor;
+import IR.Tree.Modifiers;
+import Util.Pair;
 
 public class DefinitelyWrittenCheck {
 
-       SSJavaAnalysis ssjava;
-       State state;
-       CallGraph callGraph;
+  SSJavaAnalysis ssjava;
+  State state;
+  CallGraph callGraph;
+
+  // maps a descriptor to its known dependents: namely
+  // methods or tasks that call the descriptor's method
+  // AND are part of this analysis (reachable from main)
+  private Hashtable<Descriptor, Set<MethodDescriptor>> mapDescriptorToSetDependents;
+
+  // maps a flat node to its WrittenSet: this keeps all heap path overwritten
+  // previously.
+  private Hashtable<FlatNode, Set<NTuple<Descriptor>>> mapFlatNodeToWrittenSet;
+
+  // maps a temp descriptor to its heap path
+  // each temp descriptor has a unique heap path since we do not allow any
+  // alias.
+  private Hashtable<Descriptor, NTuple<Descriptor>> mapHeapPath;
+
+  // maps a flat method to the READ that is the set of heap path that is
+  // expected to be written before method invocation
+  private Hashtable<FlatMethod, Set<NTuple<Descriptor>>> mapFlatMethodToRead;
+
+  // maps a flat method to the OVERWRITE that is the set of heap path that is
+  // overwritten on every possible path during method invocation
+  private Hashtable<FlatMethod, Set<NTuple<Descriptor>>> mapFlatMethodToOverWrite;
+
+  // points to method containing SSJAVA Loop
+  private MethodDescriptor methodContainingSSJavaLoop;
+
+  // maps a flatnode to definitely written analysis mapping M
+  private Hashtable<FlatNode, Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>>> definitelyWrittenResults;
+
+  // maps a method descriptor to its current summary during the analysis
+  // then analysis reaches fixed-point, this mapping will have the final summary
+  // for each method descriptor
+  private Hashtable<MethodDescriptor, ClearingSummary> mapMethodDescriptorToCompleteClearingSummary;
+
+  // maps a method descriptor to the merged incoming caller's current
+  // overwritten status
+  private Hashtable<MethodDescriptor, ClearingSummary> mapMethodDescriptorToInitialClearingSummary;
+
+  // maps a flat node to current partial results
+  private Hashtable<FlatNode, ClearingSummary> mapFlatNodeToClearingSummary;
+
+  // maps shared location to the set of descriptors which belong to the shared
+  // location
+  private Hashtable<Location, Set<Descriptor>> mapSharedLocation2DescriptorSet;
+
+  // keep current descriptors to visit in fixed-point interprocedural analysis,
+  private Stack<MethodDescriptor> methodDescriptorsToVisitStack;
+
+  // when analyzing flatcall, need to re-schedule set of callee
+  private Set<MethodDescriptor> calleesToEnqueue;
 
-       // maps a descriptor to its known dependents: namely
-       // methods or tasks that call the descriptor's method
-       // AND are part of this analysis (reachable from main)
-       private Hashtable<Descriptor, Set<MethodDescriptor>> mapDescriptorToSetDependents;
-
-       // maps a flat node to its WrittenSet: this keeps all heap path overwritten
-       // previously.
-       private Hashtable<FlatNode, Set<NTuple<Descriptor>>> mapFlatNodeToWrittenSet;
-
-       // maps a temp descriptor to its heap path
-       // each temp descriptor has a unique heap path since we do not allow any
-       // alias.
-       private Hashtable<Descriptor, NTuple<Descriptor>> mapHeapPath;
-
-       // maps a flat method to the READ that is the set of heap path that is
-       // expected to be written before method invocation
-       private Hashtable<FlatMethod, Set<NTuple<Descriptor>>> mapFlatMethodToRead;
-
-       // maps a flat method to the OVERWRITE that is the set of heap path that is
-       // overwritten on every possible path during method invocation
-       private Hashtable<FlatMethod, Set<NTuple<Descriptor>>> mapFlatMethodToOverWrite;
-
-       // points to method containing SSJAVA Loop
-       private MethodDescriptor methodContainingSSJavaLoop;
-
-       // maps a flatnode to definitely written analysis mapping M
-       private Hashtable<FlatNode, Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>>> definitelyWrittenResults;
-
-       private Set<NTuple<Descriptor>> calleeUnionBoundReadSet;
-       private Set<NTuple<Descriptor>> calleeIntersectBoundOverWriteSet;
-
-       public DefinitelyWrittenCheck(SSJavaAnalysis ssjava, State state) {
-               this.state = state;
-               this.ssjava = ssjava;
-               this.callGraph = ssjava.getCallGraph();
-               this.mapFlatNodeToWrittenSet = new Hashtable<FlatNode, Set<NTuple<Descriptor>>>();
-               this.mapDescriptorToSetDependents = new Hashtable<Descriptor, Set<MethodDescriptor>>();
-               this.mapHeapPath = new Hashtable<Descriptor, NTuple<Descriptor>>();
-               this.mapFlatMethodToRead = new Hashtable<FlatMethod, Set<NTuple<Descriptor>>>();
-               this.mapFlatMethodToOverWrite = new Hashtable<FlatMethod, Set<NTuple<Descriptor>>>();
-               this.definitelyWrittenResults = new Hashtable<FlatNode, Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>>>();
-               this.calleeUnionBoundReadSet = new HashSet<NTuple<Descriptor>>();
-               this.calleeIntersectBoundOverWriteSet = new HashSet<NTuple<Descriptor>>();
-       }
-
-       public void definitelyWrittenCheck() {
-               methodReadOverWriteAnalysis();
-               writtenAnalyis();
-       }
-
-       private void writtenAnalyis() {
-               // perform second stage analysis: intraprocedural analysis ensure that
-               // all
-               // variables are definitely written in-between the same read
-
-               // First, identify ssjava loop entrace
-               FlatMethod fm = state.getMethodFlat(methodContainingSSJavaLoop);
-               Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
-               flatNodesToVisit.add(fm);
-
-               FlatNode entrance = null;
-
-               while (!flatNodesToVisit.isEmpty()) {
-                       FlatNode fn = flatNodesToVisit.iterator().next();
-                       flatNodesToVisit.remove(fn);
-
-                       String label = (String) state.fn2labelMap.get(fn);
-                       if (label != null) {
-
-                               if (label.equals(ssjava.SSJAVA)) {
-                                       entrance = fn;
-                                       break;
-                               }
-                       }
-
-                       for (int i = 0; i < fn.numNext(); i++) {
-                               FlatNode nn = fn.getNext(i);
-                               flatNodesToVisit.add(nn);
-                       }
-               }
-
-               assert entrance != null;
-
-               writtenAnalysis_analyzeLoop(entrance);
-
-       }
-
-       private void writtenAnalysis_analyzeLoop(FlatNode entrance) {
-
-               Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
-               flatNodesToVisit.add(entrance);
-
-               while (!flatNodesToVisit.isEmpty()) {
-                       FlatNode fn = (FlatNode) flatNodesToVisit.iterator().next();
-                       flatNodesToVisit.remove(fn);
-
-                       Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> prev = definitelyWrittenResults
-                                       .get(fn);
-
-                       Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr = new Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>>();
-                       for (int i = 0; i < fn.numPrev(); i++) {
-                               FlatNode nn = fn.getPrev(i);
-                               Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> dwIn = definitelyWrittenResults
-                                               .get(nn);
-                               if (dwIn != null) {
-                                       merge(curr, dwIn);
-                               }
-                       }
-
-                       writtenAnalysis_nodeAction(fn, curr, entrance);
-
-                       // if a new result, schedule forward nodes for analysis
-                       if (!curr.equals(prev)) {
-                               definitelyWrittenResults.put(fn, curr);
-
-                               for (int i = 0; i < fn.numNext(); i++) {
-                                       FlatNode nn = fn.getNext(i);
-                                       flatNodesToVisit.add(nn);
-                               }
-                       }
-               }
-       }
-
-       private void writtenAnalysis_nodeAction(FlatNode fn,
-                       Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr,
-                       FlatNode loopEntrance) {
-               if (fn.equals(loopEntrance)) {
-                       // it reaches loop entrance: changes all flag to true
-                       Set<NTuple<Descriptor>> keySet = curr.keySet();
-                       for (Iterator iterator = keySet.iterator(); iterator.hasNext();) {
-                               NTuple<Descriptor> key = (NTuple<Descriptor>) iterator.next();
-                               Hashtable<FlatNode, Boolean> pair = curr.get(key);
-                               if (pair != null) {
-                                       Set<FlatNode> pairKeySet = pair.keySet();
-                                       for (Iterator iterator2 = pairKeySet.iterator(); iterator2
-                                                       .hasNext();) {
-                                               FlatNode pairKey = (FlatNode) iterator2.next();
-                                               pair.put(pairKey, Boolean.TRUE);
-                                       }
-                               }
-                       }
-               } else {
-                       TempDescriptor lhs;
-                       TempDescriptor rhs;
-                       FieldDescriptor fld;
-
-                       switch (fn.kind()) {
-                       case FKind.FlatOpNode: {
-                               FlatOpNode fon = (FlatOpNode) fn;
-                               lhs = fon.getDest();
-                               rhs = fon.getLeft();
-
-                               NTuple<Descriptor> rhsHeapPath = computePath(rhs);
-                               if (!rhs.getType().isImmutable()) {
-                                       mapHeapPath.put(lhs, rhsHeapPath);
-                               }
-
-                               if (fon.getOp().getOp() == Operation.ASSIGN) {
-                                       // read(rhs)
-                                       Hashtable<FlatNode, Boolean> gen = curr.get(rhsHeapPath);
-
-                                       if (gen == null) {
-                                               gen = new Hashtable<FlatNode, Boolean>();
-                                               curr.put(rhsHeapPath, gen);
-                                       }
-                                       Boolean currentStatus = gen.get(fn);
-                                       if (currentStatus == null) {
-                                               gen.put(fn, Boolean.FALSE);
-                                       } else {
-                                               if (!rhs.getType().isClass()) {
-                                                       checkFlag(currentStatus.booleanValue(), fn);
-                                               }
-                                       }
-
-                               }
-                               // write(lhs)
-                               NTuple<Descriptor> lhsHeapPath = computePath(lhs);
-                               removeHeapPath(curr, lhsHeapPath);
-                               // curr.put(lhsHeapPath, new Hashtable<FlatNode, Boolean>());
-                       }
-                               break;
-
-                       case FKind.FlatLiteralNode: {
-                               FlatLiteralNode fln = (FlatLiteralNode) fn;
-                               lhs = fln.getDst();
-
-                               // write(lhs)
-                               NTuple<Descriptor> lhsHeapPath = computePath(lhs);
-                               removeHeapPath(curr, lhsHeapPath);
-
-                       }
-                               break;
-
-                       case FKind.FlatFieldNode:
-                       case FKind.FlatElementNode: {
-
-                               FlatFieldNode ffn = (FlatFieldNode) fn;
-                               lhs = ffn.getSrc();
-                               fld = ffn.getField();
-
-                               // read field
-                               NTuple<Descriptor> srcHeapPath = mapHeapPath.get(lhs);
-                               NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(
-                                               srcHeapPath.getList());
-                               fldHeapPath.add(fld);
-                               Hashtable<FlatNode, Boolean> gen = curr.get(fldHeapPath);
-
-                               if (gen == null) {
-                                       gen = new Hashtable<FlatNode, Boolean>();
-                                       curr.put(fldHeapPath, gen);
-                               }
-
-                               Boolean currentStatus = gen.get(fn);
-                               if (currentStatus == null) {
-                                       gen.put(fn, Boolean.FALSE);
-                               } else {
-                                       checkFlag(currentStatus.booleanValue(), fn);
-                               }
-
-                       }
-                               break;
-
-                       case FKind.FlatSetFieldNode:
-                       case FKind.FlatSetElementNode: {
-
-                               FlatSetFieldNode fsfn = (FlatSetFieldNode) fn;
-                               lhs = fsfn.getDst();
-                               fld = fsfn.getField();
-
-                               // write(field)
-                               NTuple<Descriptor> lhsHeapPath = mapHeapPath.get(lhs);
-                               NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(
-                                               lhsHeapPath.getList());
-                               fldHeapPath.add(fld);
-                               removeHeapPath(curr, fldHeapPath);
-                               // curr.put(fldHeapPath, new Hashtable<FlatNode, Boolean>());
-
-                       }
-                               break;
-
-                       case FKind.FlatCall: {
-
-                               FlatCall fc = (FlatCall) fn;
-
-                               bindHeapPathCallerArgWithCaleeParam(fc);
-
-                               // add <hp,statement,false> in which hp is an element of
-                               // READ_bound set
-                               // of callee: callee has 'read' requirement!
-                               for (Iterator iterator = calleeUnionBoundReadSet.iterator(); iterator
-                                               .hasNext();) {
-                                       NTuple<Descriptor> read = (NTuple<Descriptor>) iterator
-                                                       .next();
-
-                                       Hashtable<FlatNode, Boolean> gen = curr.get(read);
-                                       if (gen == null) {
-                                               gen = new Hashtable<FlatNode, Boolean>();
-                                               curr.put(read, gen);
-                                       }
-                                       Boolean currentStatus = gen.get(fn);
-                                       if (currentStatus == null) {
-                                               gen.put(fn, Boolean.FALSE);
-                                       } else {
-                                               checkFlag(currentStatus.booleanValue(), fn);
-                                       }
-                               }
-
-                               // removes <hp,statement,flag> if hp is an element of
-                               // OVERWRITE_bound
-                               // set of callee. it means that callee will overwrite it
-                               for (Iterator iterator = calleeIntersectBoundOverWriteSet
-                                               .iterator(); iterator.hasNext();) {
-                                       NTuple<Descriptor> write = (NTuple<Descriptor>) iterator
-                                                       .next();
-                                       removeHeapPath(curr, write);
-                                       // curr.put(write, new Hashtable<FlatNode, Boolean>());
-                               }
-                       }
-                               break;
-
-                       }
-
-               }
-
-       }
-
-       private void removeHeapPath(
-                       Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr,
-                       NTuple<Descriptor> hp) {
-
-               // removes all of heap path that starts with prefix 'hp'
-               // since any reference overwrite along heap path gives overwriting side
-               // effects on the value
-
-               Set<NTuple<Descriptor>> keySet = curr.keySet();
-               for (Iterator<NTuple<Descriptor>> iter = keySet.iterator(); iter
-                               .hasNext();) {
-                       NTuple<Descriptor> key = iter.next();
-                       if (key.startsWith(hp)) {
-                               curr.put(key, new Hashtable<FlatNode, Boolean>());
-                       }
-               }
-
-       }
-
-       private void bindHeapPathCallerArgWithCaleeParam(FlatCall fc) {
-               // compute all possible callee set
-               // transform all READ/OVERWRITE set from the any possible
-               // callees to the
-               // caller
-               MethodDescriptor mdCallee = fc.getMethod();
-               FlatMethod fmCallee = state.getMethodFlat(mdCallee);
-               Set<MethodDescriptor> setPossibleCallees = new HashSet<MethodDescriptor>();
-               TypeDescriptor typeDesc = fc.getThis().getType();
-               setPossibleCallees.addAll(callGraph.getMethods(mdCallee, typeDesc));
-
-               // create mapping from arg idx to its heap paths
-               Hashtable<Integer, NTuple<Descriptor>> mapArgIdx2CallerArgHeapPath = new Hashtable<Integer, NTuple<Descriptor>>();
-
-               // arg idx is starting from 'this' arg
-               NTuple<Descriptor> thisHeapPath = new NTuple<Descriptor>();
-               thisHeapPath.add(fc.getThis());
-               mapArgIdx2CallerArgHeapPath.put(Integer.valueOf(0), thisHeapPath);
-
-               for (int i = 0; i < fc.numArgs(); i++) {
-                       TempDescriptor arg = fc.getArg(i);
-                       NTuple<Descriptor> argHeapPath = computePath(arg);
-                       mapArgIdx2CallerArgHeapPath
-                                       .put(Integer.valueOf(i + 1), argHeapPath);
-               }
-
-               for (Iterator iterator = setPossibleCallees.iterator(); iterator
-                               .hasNext();) {
-                       MethodDescriptor callee = (MethodDescriptor) iterator.next();
-                       FlatMethod calleeFlatMethod = state.getMethodFlat(callee);
-
-                       // binding caller's args and callee's params
-                       Set<NTuple<Descriptor>> calleeReadSet = mapFlatMethodToRead
-                                       .get(calleeFlatMethod);
-                       if (calleeReadSet == null) {
-                               calleeReadSet = new HashSet<NTuple<Descriptor>>();
-                               mapFlatMethodToRead.put(calleeFlatMethod, calleeReadSet);
-                       }
-                       Set<NTuple<Descriptor>> calleeOverWriteSet = mapFlatMethodToOverWrite
-                                       .get(calleeFlatMethod);
-                       if (calleeOverWriteSet == null) {
-                               calleeOverWriteSet = new HashSet<NTuple<Descriptor>>();
-                               mapFlatMethodToOverWrite.put(calleeFlatMethod,
-                                               calleeOverWriteSet);
-                       }
-
-                       Hashtable<Integer, TempDescriptor> mapParamIdx2ParamTempDesc = new Hashtable<Integer, TempDescriptor>();
-                       for (int i = 0; i < calleeFlatMethod.numParameters(); i++) {
-                               TempDescriptor param = calleeFlatMethod.getParameter(i);
-                               mapParamIdx2ParamTempDesc.put(Integer.valueOf(i), param);
-                       }
-
-                       Set<NTuple<Descriptor>> calleeBoundReadSet = bindSet(calleeReadSet,
-                                       mapParamIdx2ParamTempDesc, mapArgIdx2CallerArgHeapPath);
-                       // union of the current read set and the current callee's
-                       // read set
-                       calleeUnionBoundReadSet.addAll(calleeBoundReadSet);
-                       Set<NTuple<Descriptor>> calleeBoundWriteSet = bindSet(
-                                       calleeOverWriteSet, mapParamIdx2ParamTempDesc,
-                                       mapArgIdx2CallerArgHeapPath);
-                       // intersection of the current overwrite set and the current
-                       // callee's
-                       // overwrite set
-                       merge(calleeIntersectBoundOverWriteSet, calleeBoundWriteSet);
-               }
-
-       }
-
-       private void checkFlag(boolean booleanValue, FlatNode fn) {
-               if (booleanValue) {
-                       throw new Error(
-                                       "There is a variable who comes back to the same read statement at the out-most iteration at "
-                                                       + methodContainingSSJavaLoop.getClassDesc()
-                                                                       .getSourceFileName()
-                                                       + "::"
-                                                       + fn.getNumLine());
-               }
-       }
-
-       private void merge(
-                       Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr,
-                       Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> in) {
-
-               Set<NTuple<Descriptor>> inKeySet = in.keySet();
-               for (Iterator iterator = inKeySet.iterator(); iterator.hasNext();) {
-                       NTuple<Descriptor> inKey = (NTuple<Descriptor>) iterator.next();
-                       Hashtable<FlatNode, Boolean> inPair = in.get(inKey);
-
-                       Set<FlatNode> pairKeySet = inPair.keySet();
-                       for (Iterator iterator2 = pairKeySet.iterator(); iterator2
-                                       .hasNext();) {
-                               FlatNode pairKey = (FlatNode) iterator2.next();
-                               Boolean inFlag = inPair.get(pairKey);
-
-                               Hashtable<FlatNode, Boolean> currPair = curr.get(inKey);
-                               if (currPair == null) {
-                                       currPair = new Hashtable<FlatNode, Boolean>();
-                                       curr.put(inKey, currPair);
-                               }
-
-                               Boolean currFlag = currPair.get(pairKey);
-                               // by default, flag is set by false
-                               if (currFlag == null) {
-                                       currFlag = Boolean.FALSE;
-                               }
-                               currFlag = Boolean.valueOf(inFlag.booleanValue()
-                                               | currFlag.booleanValue());
-                               currPair.put(pairKey, currFlag);
-                       }
-
-               }
-
-       }
-
-       private void methodReadOverWriteAnalysis() {
-               // perform method READ/OVERWRITE analysis
-               Set<MethodDescriptor> methodDescriptorsToAnalyze = new HashSet<MethodDescriptor>();
-               methodDescriptorsToAnalyze.addAll(ssjava.getAnnotationRequireSet());
-
-               LinkedList<MethodDescriptor> sortedDescriptors = topologicalSort(methodDescriptorsToAnalyze);
-
-               // no need to analyze method having ssjava loop
-               methodContainingSSJavaLoop = sortedDescriptors.removeFirst();
-
-               // current descriptors to visit in fixed-point interprocedural analysis,
-               // prioritized by
-               // dependency in the call graph
-               Stack<MethodDescriptor> methodDescriptorsToVisitStack = new Stack<MethodDescriptor>();
-
-               Set<MethodDescriptor> methodDescriptorToVistSet = new HashSet<MethodDescriptor>();
-               methodDescriptorToVistSet.addAll(sortedDescriptors);
-
-               while (!sortedDescriptors.isEmpty()) {
-                       MethodDescriptor md = sortedDescriptors.removeFirst();
-                       methodDescriptorsToVisitStack.add(md);
-               }
-
-               // analyze scheduled methods until there are no more to visit
-               while (!methodDescriptorsToVisitStack.isEmpty()) {
-                       // start to analyze leaf node
-                       MethodDescriptor md = methodDescriptorsToVisitStack.pop();
-                       FlatMethod fm = state.getMethodFlat(md);
-
-                       Set<NTuple<Descriptor>> readSet = new HashSet<NTuple<Descriptor>>();
-                       Set<NTuple<Descriptor>> overWriteSet = new HashSet<NTuple<Descriptor>>();
-
-                       methodReadOverWrite_analyzeMethod(fm, readSet, overWriteSet);
-
-                       Set<NTuple<Descriptor>> prevRead = mapFlatMethodToRead.get(fm);
-                       Set<NTuple<Descriptor>> prevOverWrite = mapFlatMethodToOverWrite
-                                       .get(fm);
-
-                       if (!(readSet.equals(prevRead) && overWriteSet
-                                       .equals(prevOverWrite))) {
-                               mapFlatMethodToRead.put(fm, readSet);
-                               mapFlatMethodToOverWrite.put(fm, overWriteSet);
-
-                               // results for callee changed, so enqueue dependents caller for
-                               // further
-                               // analysis
-                               Iterator<MethodDescriptor> depsItr = getDependents(md)
-                                               .iterator();
-                               while (depsItr.hasNext()) {
-                                       MethodDescriptor methodNext = depsItr.next();
-                                       if (!methodDescriptorsToVisitStack.contains(methodNext)
-                                                       && methodDescriptorToVistSet.contains(methodNext)) {
-                                               methodDescriptorsToVisitStack.add(methodNext);
-                                       }
-
-                               }
-
-                       }
-
-               }
-
-       }
-
-       private void methodReadOverWrite_analyzeMethod(FlatMethod fm,
-                       Set<NTuple<Descriptor>> readSet,
-                       Set<NTuple<Descriptor>> overWriteSet) {
-               if (state.SSJAVADEBUG) {
-                       System.out.println("Definitely written Analyzing: " + fm);
-               }
-
-               // intraprocedural analysis
-               Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
-               flatNodesToVisit.add(fm);
-
-               while (!flatNodesToVisit.isEmpty()) {
-                       FlatNode fn = flatNodesToVisit.iterator().next();
-                       flatNodesToVisit.remove(fn);
-
-                       Set<NTuple<Descriptor>> curr = new HashSet<NTuple<Descriptor>>();
-
-                       for (int i = 0; i < fn.numPrev(); i++) {
-                               FlatNode prevFn = fn.getPrev(i);
-                               Set<NTuple<Descriptor>> in = mapFlatNodeToWrittenSet
-                                               .get(prevFn);
-                               if (in != null) {
-                                       merge(curr, in);
-                               }
-                       }
-
-                       methodReadOverWrite_nodeActions(fn, curr, readSet, overWriteSet);
-
-                       mapFlatNodeToWrittenSet.put(fn, curr);
-
-                       for (int i = 0; i < fn.numNext(); i++) {
-                               FlatNode nn = fn.getNext(i);
-                               flatNodesToVisit.add(nn);
-                       }
-
-               }
-
-       }
-
-       private void methodReadOverWrite_nodeActions(FlatNode fn,
-                       Set<NTuple<Descriptor>> writtenSet,
-                       Set<NTuple<Descriptor>> readSet,
-                       Set<NTuple<Descriptor>> overWriteSet) {
-               TempDescriptor lhs;
-               TempDescriptor rhs;
-               FieldDescriptor fld;
-
-               switch (fn.kind()) {
-               case FKind.FlatMethod: {
-
-                       // set up initial heap paths for method parameters
-                       FlatMethod fm = (FlatMethod) fn;
-                       for (int i = 0; i < fm.numParameters(); i++) {
-                               TempDescriptor param = fm.getParameter(i);
-                               NTuple<Descriptor> heapPath = new NTuple<Descriptor>();
-                               heapPath.add(param);
-                               mapHeapPath.put(param, heapPath);
-                       }
-               }
-                       break;
-
-               case FKind.FlatOpNode: {
-                       FlatOpNode fon = (FlatOpNode) fn;
-                       // for a normal assign node, need to propagate lhs's heap path to
-                       // rhs
-                       if (fon.getOp().getOp() == Operation.ASSIGN) {
-                               rhs = fon.getLeft();
-                               lhs = fon.getDest();
-
-                               NTuple<Descriptor> rhsHeapPath = mapHeapPath.get(rhs);
-                               if (rhsHeapPath != null) {
-                                       mapHeapPath.put(lhs, mapHeapPath.get(rhs));
-                               }
-
-                       }
-               }
-                       break;
-
-               case FKind.FlatFieldNode:
-               case FKind.FlatElementNode: {
-
-                       // y=x.f;
-
-                       FlatFieldNode ffn = (FlatFieldNode) fn;
-                       lhs = ffn.getDst();
-                       rhs = ffn.getSrc();
-                       fld = ffn.getField();
-
-                       // set up heap path
-                       NTuple<Descriptor> srcHeapPath = mapHeapPath.get(rhs);
-                       NTuple<Descriptor> readingHeapPath = new NTuple<Descriptor>(
-                                       srcHeapPath.getList());
-                       readingHeapPath.add(fld);
-                       mapHeapPath.put(lhs, readingHeapPath);
-
-                       // read (x.f)
-                       // if WT doesnot have hp(x.f), add hp(x.f) to READ
-                       if (!writtenSet.contains(readingHeapPath)) {
-                               readSet.add(readingHeapPath);
-                       }
-
-                       // need to kill hp(x.f) from WT
-                       writtenSet.remove(readingHeapPath);
-
-               }
-                       break;
-
-               case FKind.FlatSetFieldNode:
-               case FKind.FlatSetElementNode: {
-
-                       // x.f=y;
-                       FlatSetFieldNode fsfn = (FlatSetFieldNode) fn;
-                       lhs = fsfn.getDst();
-                       fld = fsfn.getField();
-                       rhs = fsfn.getSrc();
-
-                       // set up heap path
-                       NTuple<Descriptor> lhsHeapPath = mapHeapPath.get(lhs);
-                       NTuple<Descriptor> newHeapPath = new NTuple<Descriptor>(
-                                       lhsHeapPath.getList());
-                       newHeapPath.add(fld);
-                       mapHeapPath.put(fld, newHeapPath);
-
-                       // write(x.f)
-                       // need to add hp(y) to WT
-                       writtenSet.add(newHeapPath);
-
-               }
-                       break;
-
-               case FKind.FlatCall: {
-
-                       FlatCall fc = (FlatCall) fn;
-
-                       bindHeapPathCallerArgWithCaleeParam(fc);
-
-                       // add heap path, which is an element of READ_bound set and is not
-                       // an
-                       // element of WT set, to the caller's READ set
-                       for (Iterator iterator = calleeUnionBoundReadSet.iterator(); iterator
-                                       .hasNext();) {
-                               NTuple<Descriptor> read = (NTuple<Descriptor>) iterator.next();
-                               if (!writtenSet.contains(read)) {
-                                       readSet.add(read);
-                               }
-                       }
-                       writtenSet.removeAll(calleeUnionBoundReadSet);
-
-                       // add heap path, which is an element of OVERWRITE_bound set, to the
-                       // caller's WT set
-                       for (Iterator iterator = calleeIntersectBoundOverWriteSet
-                                       .iterator(); iterator.hasNext();) {
-                               NTuple<Descriptor> write = (NTuple<Descriptor>) iterator.next();
-                               writtenSet.add(write);
-                       }
-
-               }
-                       break;
-
-               case FKind.FlatExit: {
-                       // merge the current written set with OVERWRITE set
-                       merge(overWriteSet, writtenSet);
-               }
-                       break;
-
-               }
-
-       }
-
-       private void merge(Set<NTuple<Descriptor>> curr, Set<NTuple<Descriptor>> in) {
-
-               if (curr.isEmpty()) {
-                       // WrittenSet has a special initial value which covers all possible
-                       // elements
-                       // For the first time of intersection, we can take all previous set
-                       curr.addAll(in);
-               } else {
-                       // otherwise, current set is the intersection of the two sets
-                       curr.retainAll(in);
-               }
-
-       }
-
-       // combine two heap path
-       private NTuple<Descriptor> combine(NTuple<Descriptor> callerIn,
-                       NTuple<Descriptor> calleeIn) {
-               NTuple<Descriptor> combined = new NTuple<Descriptor>();
-
-               for (int i = 0; i < callerIn.size(); i++) {
-                       combined.add(callerIn.get(i));
-               }
-
-               // the first element of callee's heap path represents parameter
-               // so we skip the first one since it is already added from caller's heap
-               // path
-               for (int i = 1; i < calleeIn.size(); i++) {
-                       combined.add(calleeIn.get(i));
-               }
-
-               return combined;
-       }
-
-       private Set<NTuple<Descriptor>> bindSet(Set<NTuple<Descriptor>> calleeSet,
-                       Hashtable<Integer, TempDescriptor> mapParamIdx2ParamTempDesc,
-                       Hashtable<Integer, NTuple<Descriptor>> mapCallerArgIdx2HeapPath) {
-
-               Set<NTuple<Descriptor>> boundedCalleeSet = new HashSet<NTuple<Descriptor>>();
-
-               Set<Integer> keySet = mapCallerArgIdx2HeapPath.keySet();
-               for (Iterator iterator = keySet.iterator(); iterator.hasNext();) {
-                       Integer idx = (Integer) iterator.next();
-
-                       NTuple<Descriptor> callerArgHeapPath = mapCallerArgIdx2HeapPath
-                                       .get(idx);
-                       TempDescriptor calleeParam = mapParamIdx2ParamTempDesc.get(idx);
-
-                       for (Iterator iterator2 = calleeSet.iterator(); iterator2.hasNext();) {
-                               NTuple<Descriptor> element = (NTuple<Descriptor>) iterator2
-                                               .next();
-                               if (element.startsWith(calleeParam)) {
-                                       NTuple<Descriptor> boundElement = combine(
-                                                       callerArgHeapPath, element);
-                                       boundedCalleeSet.add(boundElement);
-                               }
-
-                       }
-
-               }
-               return boundedCalleeSet;
-
-       }
-
-       // Borrowed it from disjoint analysis
-       private LinkedList<MethodDescriptor> topologicalSort(
-                       Set<MethodDescriptor> toSort) {
-
-               Set<MethodDescriptor> discovered = new HashSet<MethodDescriptor>();
-
-               LinkedList<MethodDescriptor> sorted = new LinkedList<MethodDescriptor>();
-
-               Iterator<MethodDescriptor> itr = toSort.iterator();
-               while (itr.hasNext()) {
-                       MethodDescriptor d = itr.next();
-
-                       if (!discovered.contains(d)) {
-                               dfsVisit(d, toSort, sorted, discovered);
-                       }
-               }
-
-               return sorted;
-       }
-
-       // While we're doing DFS on call graph, remember
-       // dependencies for efficient queuing of methods
-       // during interprocedural analysis:
-       //
-       // a dependent of a method decriptor d for this analysis is:
-       // 1) a method or task that invokes d
-       // 2) in the descriptorsToAnalyze set
-       private void dfsVisit(MethodDescriptor md, Set<MethodDescriptor> toSort,
-                       LinkedList<MethodDescriptor> sorted,
-                       Set<MethodDescriptor> discovered) {
-
-               discovered.add(md);
-
-               // otherwise call graph guides DFS
-               Iterator itr = callGraph.getCallerSet(md).iterator();
-               while (itr.hasNext()) {
-                       MethodDescriptor dCaller = (MethodDescriptor) itr.next();
-
-                       // only consider callers in the original set to analyze
-                       if (!toSort.contains(dCaller)) {
-                               continue;
-                       }
-
-                       if (!discovered.contains(dCaller)) {
-                               addDependent(md, // callee
-                                               dCaller // caller
-                               );
-
-                               dfsVisit(dCaller, toSort, sorted, discovered);
-                       }
-               }
-
-               // for leaf-nodes last now!
-               sorted.addLast(md);
-       }
-
-       // a dependent of a method decriptor d for this analysis is:
-       // 1) a method or task that invokes d
-       // 2) in the descriptorsToAnalyze set
-       private void addDependent(MethodDescriptor callee, MethodDescriptor caller) {
-               Set<MethodDescriptor> deps = mapDescriptorToSetDependents.get(callee);
-               if (deps == null) {
-                       deps = new HashSet<MethodDescriptor>();
-               }
-               deps.add(caller);
-               mapDescriptorToSetDependents.put(callee, deps);
-       }
-
-       private Set<MethodDescriptor> getDependents(MethodDescriptor callee) {
-               Set<MethodDescriptor> deps = mapDescriptorToSetDependents.get(callee);
-               if (deps == null) {
-                       deps = new HashSet<MethodDescriptor>();
-                       mapDescriptorToSetDependents.put(callee, deps);
-               }
-               return deps;
-       }
-
-       private NTuple<Descriptor> computePath(TempDescriptor td) {
-               // generate proper path fot input td
-               // if td is local variable, it just generate one element tuple path
-               if (mapHeapPath.containsKey(td)) {
-                       return mapHeapPath.get(td);
-               } else {
-                       NTuple<Descriptor> path = new NTuple<Descriptor>();
-                       path.add(td);
-                       return path;
-               }
-       }
+  public static final String arrayElementFieldName = "___element_";
+  static protected Hashtable<TypeDescriptor, FieldDescriptor> mapTypeToArrayField;
+
+  private Set<ClearingSummary> possibleCalleeCompleteSummarySetToCaller;
+
+  private LinkedList<MethodDescriptor> sortedDescriptors;
+
+  private FlatNode ssjavaLoopEntrance;
+  private LoopFinder ssjavaLoop;
+  private Set<FlatNode> loopIncElements;
+
+  private Set<NTuple<Descriptor>> calleeUnionBoundReadSet;
+  private Set<NTuple<Descriptor>> calleeIntersectBoundOverWriteSet;
+
+  private TempDescriptor LOCAL;
+
+  public DefinitelyWrittenCheck(SSJavaAnalysis ssjava, State state) {
+    this.state = state;
+    this.ssjava = ssjava;
+    this.callGraph = ssjava.getCallGraph();
+    this.mapFlatNodeToWrittenSet = new Hashtable<FlatNode, Set<NTuple<Descriptor>>>();
+    this.mapDescriptorToSetDependents = new Hashtable<Descriptor, Set<MethodDescriptor>>();
+    this.mapHeapPath = new Hashtable<Descriptor, NTuple<Descriptor>>();
+    this.mapFlatMethodToRead = new Hashtable<FlatMethod, Set<NTuple<Descriptor>>>();
+    this.mapFlatMethodToOverWrite = new Hashtable<FlatMethod, Set<NTuple<Descriptor>>>();
+    this.definitelyWrittenResults =
+        new Hashtable<FlatNode, Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>>>();
+    this.calleeUnionBoundReadSet = new HashSet<NTuple<Descriptor>>();
+    this.calleeIntersectBoundOverWriteSet = new HashSet<NTuple<Descriptor>>();
+
+    this.mapMethodDescriptorToCompleteClearingSummary =
+        new Hashtable<MethodDescriptor, ClearingSummary>();
+    this.mapMethodDescriptorToInitialClearingSummary =
+        new Hashtable<MethodDescriptor, ClearingSummary>();
+    this.mapSharedLocation2DescriptorSet = new Hashtable<Location, Set<Descriptor>>();
+    this.methodDescriptorsToVisitStack = new Stack<MethodDescriptor>();
+    this.calleesToEnqueue = new HashSet<MethodDescriptor>();
+    this.possibleCalleeCompleteSummarySetToCaller = new HashSet<ClearingSummary>();
+    this.mapTypeToArrayField = new Hashtable<TypeDescriptor, FieldDescriptor>();
+    this.LOCAL = new TempDescriptor("LOCAL");
+  }
+
+  public void definitelyWrittenCheck() {
+    if (!ssjava.getAnnotationRequireSet().isEmpty()) {
+      methodReadOverWriteAnalysis();
+      writtenAnalyis();
+      sharedLocationAnalysis();
+      checkSharedLocationResult();
+    }
+  }
+
+  private void checkSharedLocationResult() {
+
+    // mapping of method containing ssjava loop has the final result of
+    // shared location analysis
+    ClearingSummary result =
+        mapMethodDescriptorToCompleteClearingSummary.get(sortedDescriptors.peekFirst());
+
+
+    Set<NTuple<Descriptor>> hpKeySet = result.keySet();
+    for (Iterator iterator = hpKeySet.iterator(); iterator.hasNext();) {
+      NTuple<Descriptor> hpKey = (NTuple<Descriptor>) iterator.next();
+      SharedStatus state = result.get(hpKey);
+      Set<Location> locKeySet = state.getLocationSet();
+      for (Iterator iterator2 = locKeySet.iterator(); iterator2.hasNext();) {
+        Location locKey = (Location) iterator2.next();
+        if (!state.getFlag(locKey)) {
+          throw new Error(
+              "Some concrete locations of the shared abstract location are not cleared at the same time.");
+        }
+      }
+    }
+
+  }
+
+  private void sharedLocationAnalysis() {
+    // verify that all concrete locations of shared location are cleared out at
+    // the same time once per the out-most loop
+
+    computeReadSharedDescriptorSet();
+
+    methodDescriptorsToVisitStack.clear();
+
+    methodDescriptorsToVisitStack.add(sortedDescriptors.peekFirst());
+
+    // analyze scheduled methods until there are no more to visit
+    while (!methodDescriptorsToVisitStack.isEmpty()) {
+      MethodDescriptor md = methodDescriptorsToVisitStack.pop();
+
+      ClearingSummary completeSummary =
+          sharedLocation_analyzeMethod(md, (md.equals(methodContainingSSJavaLoop)));
+
+      ClearingSummary prevCompleteSummary = mapMethodDescriptorToCompleteClearingSummary.get(md);
+
+      if (!completeSummary.equals(prevCompleteSummary)) {
+
+        mapMethodDescriptorToCompleteClearingSummary.put(md, completeSummary);
+
+        // results for callee changed, so enqueue dependents caller for
+        // further analysis
+        Iterator<MethodDescriptor> depsItr = getDependents(md).iterator();
+        while (depsItr.hasNext()) {
+          MethodDescriptor methodNext = depsItr.next();
+          if (!methodDescriptorsToVisitStack.contains(methodNext)) {
+            methodDescriptorsToVisitStack.add(methodNext);
+          }
+        }
+
+        // if there is set of callee to be analyzed,
+        // add this set into the top of stack
+        Iterator<MethodDescriptor> calleeIter = calleesToEnqueue.iterator();
+        while (calleeIter.hasNext()) {
+          MethodDescriptor mdNext = calleeIter.next();
+          if (!methodDescriptorsToVisitStack.contains(mdNext)) {
+            methodDescriptorsToVisitStack.add(mdNext);
+          }
+        }
+        calleesToEnqueue.clear();
+
+      }
+
+    }
+
+  }
+
+  private ClearingSummary sharedLocation_analyzeMethod(MethodDescriptor md,
+      boolean onlyVisitSSJavaLoop) {
+
+    if (state.SSJAVADEBUG) {
+      System.out.println("Definitely written for shared locations Analyzing: " + md + " "
+          + onlyVisitSSJavaLoop);
+    }
+
+    FlatMethod fm = state.getMethodFlat(md);
+
+    // intraprocedural analysis
+    Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
+
+    // start a new mapping of partial results for each flat node
+    mapFlatNodeToClearingSummary = new Hashtable<FlatNode, ClearingSummary>();
+
+    if (onlyVisitSSJavaLoop) {
+      flatNodesToVisit.add(ssjavaLoopEntrance);
+    } else {
+      flatNodesToVisit.add(fm);
+    }
+
+    Set<FlatNode> returnNodeSet = new HashSet<FlatNode>();
+
+    while (!flatNodesToVisit.isEmpty()) {
+      FlatNode fn = flatNodesToVisit.iterator().next();
+      flatNodesToVisit.remove(fn);
+
+      ClearingSummary curr = new ClearingSummary();
+
+      Set<ClearingSummary> prevSet = new HashSet<ClearingSummary>();
+      for (int i = 0; i < fn.numPrev(); i++) {
+        FlatNode prevFn = fn.getPrev(i);
+        ClearingSummary in = mapFlatNodeToClearingSummary.get(prevFn);
+        if (in != null) {
+          prevSet.add(in);
+        }
+      }
+      mergeSharedLocationAnaylsis(curr, prevSet);
+
+      sharedLocation_nodeActions(md, fn, curr, returnNodeSet, onlyVisitSSJavaLoop);
+      ClearingSummary clearingPrev = mapFlatNodeToClearingSummary.get(fn);
+
+      if (!curr.equals(clearingPrev)) {
+        mapFlatNodeToClearingSummary.put(fn, curr);
+
+        for (int i = 0; i < fn.numNext(); i++) {
+          FlatNode nn = fn.getNext(i);
+
+          if (!onlyVisitSSJavaLoop || (onlyVisitSSJavaLoop && loopIncElements.contains(nn))) {
+            flatNodesToVisit.add(nn);
+          }
+
+        }
+      }
+
+    }
+
+    ClearingSummary completeSummary = new ClearingSummary();
+    Set<ClearingSummary> summarySet = new HashSet<ClearingSummary>();
+
+    if (onlyVisitSSJavaLoop) {
+      // when analyzing ssjava loop,
+      // complete summary is merging of all previous nodes of ssjava loop
+      // entrance
+      for (int i = 0; i < ssjavaLoopEntrance.numPrev(); i++) {
+        ClearingSummary frnSummary =
+            mapFlatNodeToClearingSummary.get(ssjavaLoopEntrance.getPrev(i));
+        if (frnSummary != null) {
+          summarySet.add(frnSummary);
+        }
+      }
+    } else {
+      // merging all exit node summary into the complete summary
+      if (!returnNodeSet.isEmpty()) {
+        for (Iterator iterator = returnNodeSet.iterator(); iterator.hasNext();) {
+          FlatNode frn = (FlatNode) iterator.next();
+          ClearingSummary frnSummary = mapFlatNodeToClearingSummary.get(frn);
+          summarySet.add(frnSummary);
+        }
+      }
+    }
+    mergeSharedLocationAnaylsis(completeSummary, summarySet);
+    return completeSummary;
+  }
+
+  private void sharedLocation_nodeActions(MethodDescriptor caller, FlatNode fn,
+      ClearingSummary curr, Set<FlatNode> returnNodeSet, boolean isSSJavaLoop) {
+
+    TempDescriptor lhs;
+    TempDescriptor rhs;
+    FieldDescriptor fld;
+    switch (fn.kind()) {
+
+    case FKind.FlatMethod: {
+      FlatMethod fm = (FlatMethod) fn;
+
+      ClearingSummary summaryFromCaller =
+          mapMethodDescriptorToInitialClearingSummary.get(fm.getMethod());
+
+      Set<ClearingSummary> inSet = new HashSet<ClearingSummary>();
+      inSet.add(summaryFromCaller);
+      mergeSharedLocationAnaylsis(curr, inSet);
+
+    }
+      break;
+
+    case FKind.FlatOpNode: {
+      FlatOpNode fon = (FlatOpNode) fn;
+      lhs = fon.getDest();
+      rhs = fon.getLeft();
+
+      if (fon.getOp().getOp() == Operation.ASSIGN) {
+        if (rhs.getType().isImmutable() && isSSJavaLoop) {
+          // in ssjavaloop, we need to take care about reading local variables!
+          NTuple<Descriptor> rhsHeapPath = new NTuple<Descriptor>();
+          NTuple<Descriptor> lhsHeapPath = new NTuple<Descriptor>();
+          rhsHeapPath.add(LOCAL);
+          lhsHeapPath.add(LOCAL);
+          if (!lhs.getSymbol().startsWith("neverused")) {
+            readLocation(curr, rhsHeapPath, rhs);
+            writeLocation(curr, lhsHeapPath, lhs);
+          }
+        }
+      }
+
+    }
+      break;
+
+    case FKind.FlatFieldNode:
+    case FKind.FlatElementNode: {
+
+      FlatFieldNode ffn = (FlatFieldNode) fn;
+      lhs = ffn.getDst();
+      rhs = ffn.getSrc();
+      fld = ffn.getField();
+
+      // read field
+      NTuple<Descriptor> srcHeapPath = mapHeapPath.get(rhs);
+      NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(srcHeapPath.getList());
+
+      if (fld.getType().isImmutable()) {
+        readLocation(curr, fldHeapPath, fld);
+      }
+
+    }
+      break;
+
+    case FKind.FlatSetFieldNode:
+    case FKind.FlatSetElementNode: {
+
+      FlatSetFieldNode fsfn = (FlatSetFieldNode) fn;
+      lhs = fsfn.getDst();
+      fld = fsfn.getField();
+
+      // write(field)
+      NTuple<Descriptor> lhsHeapPath = computePath(lhs);
+      NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(lhsHeapPath.getList());
+      if (fld.getType().isImmutable()) {
+        writeLocation(curr, fldHeapPath, fld);
+      } else {
+        // updates reference field case:
+        // 2. if there exists a tuple t in sharing summary that starts with
+        // hp(x) then, set flag of tuple t to 'true'
+        fldHeapPath.add(fld);
+        Set<NTuple<Descriptor>> hpKeySet = curr.keySet();
+        for (Iterator iterator = hpKeySet.iterator(); iterator.hasNext();) {
+          NTuple<Descriptor> hpKey = (NTuple<Descriptor>) iterator.next();
+          if (hpKey.startsWith(fldHeapPath)) {
+            curr.get(hpKey).updateFlag(true);
+          }
+        }
+      }
+
+    }
+      break;
+
+    case FKind.FlatCall: {
+
+      FlatCall fc = (FlatCall) fn;
+
+      // find out the set of callees
+      MethodDescriptor mdCallee = fc.getMethod();
+      FlatMethod fmCallee = state.getMethodFlat(mdCallee);
+      Set<MethodDescriptor> setPossibleCallees = new HashSet<MethodDescriptor>();
+      TypeDescriptor typeDesc = fc.getThis().getType();
+      setPossibleCallees.addAll(callGraph.getMethods(mdCallee, typeDesc));
+
+      possibleCalleeCompleteSummarySetToCaller.clear();
+
+      for (Iterator iterator = setPossibleCallees.iterator(); iterator.hasNext();) {
+        MethodDescriptor mdPossibleCallee = (MethodDescriptor) iterator.next();
+        FlatMethod calleeFlatMethod = state.getMethodFlat(mdPossibleCallee);
+
+        addDependent(mdPossibleCallee, // callee
+            caller); // caller
+
+        calleesToEnqueue.add(mdPossibleCallee);
+
+        // updates possible callee's initial summary using caller's current
+        // writing status
+        ClearingSummary prevCalleeInitSummary =
+            mapMethodDescriptorToInitialClearingSummary.get(mdPossibleCallee);
+
+        ClearingSummary calleeInitSummary =
+            bindHeapPathOfCalleeCallerEffects(fc, calleeFlatMethod, curr);
+
+        // if changes, update the init summary
+        // and reschedule the callee for analysis
+        if (!calleeInitSummary.equals(prevCalleeInitSummary)) {
+
+          if (!methodDescriptorsToVisitStack.contains(mdPossibleCallee)) {
+            methodDescriptorsToVisitStack.add(mdPossibleCallee);
+          }
+          mapMethodDescriptorToInitialClearingSummary.put(mdPossibleCallee, calleeInitSummary);
+        }
+
+      }
+
+      // contribute callee's writing effects to the caller
+      mergeSharedLocationAnaylsis(curr, possibleCalleeCompleteSummarySetToCaller);
+
+    }
+      break;
+
+    case FKind.FlatReturnNode: {
+      returnNodeSet.add(fn);
+    }
+      break;
+
+    }
+
+  }
+
+  private ClearingSummary bindHeapPathOfCalleeCallerEffects(FlatCall fc,
+      FlatMethod calleeFlatMethod, ClearingSummary curr) {
+
+    ClearingSummary boundSet = new ClearingSummary();
+
+    // create mapping from arg idx to its heap paths
+    Hashtable<Integer, NTuple<Descriptor>> mapArgIdx2CallerArgHeapPath =
+        new Hashtable<Integer, NTuple<Descriptor>>();
+
+    // arg idx is starting from 'this' arg
+    NTuple<Descriptor> thisHeapPath = mapHeapPath.get(fc.getThis());
+    if (thisHeapPath == null) {
+      // method is called without creating new flat node representing 'this'
+      thisHeapPath = new NTuple<Descriptor>();
+      thisHeapPath.add(fc.getThis());
+    }
+
+    mapArgIdx2CallerArgHeapPath.put(Integer.valueOf(0), thisHeapPath);
+
+    for (int i = 0; i < fc.numArgs(); i++) {
+      TempDescriptor arg = fc.getArg(i);
+      NTuple<Descriptor> argHeapPath = computePath(arg);
+      mapArgIdx2CallerArgHeapPath.put(Integer.valueOf(i + 1), argHeapPath);
+    }
+
+    Hashtable<Integer, TempDescriptor> mapParamIdx2ParamTempDesc =
+        new Hashtable<Integer, TempDescriptor>();
+    for (int i = 0; i < calleeFlatMethod.numParameters(); i++) {
+      TempDescriptor param = calleeFlatMethod.getParameter(i);
+      mapParamIdx2ParamTempDesc.put(Integer.valueOf(i), param);
+    }
+
+    // binding caller's writing effects to callee's params
+    for (int i = 0; i < calleeFlatMethod.numParameters(); i++) {
+      NTuple<Descriptor> argHeapPath = mapArgIdx2CallerArgHeapPath.get(Integer.valueOf(i));
+      TempDescriptor calleeParamHeapPath = mapParamIdx2ParamTempDesc.get(Integer.valueOf(i));
+
+      // iterate over caller's writing effect set
+      Set<NTuple<Descriptor>> hpKeySet = curr.keySet();
+      for (Iterator iterator = hpKeySet.iterator(); iterator.hasNext();) {
+        NTuple<Descriptor> hpKey = (NTuple<Descriptor>) iterator.next();
+        // current element is reachable caller's arg
+        // so need to bind it to the caller's side and add it to the callee's
+        // init summary
+        if (hpKey.startsWith(argHeapPath)) {
+          NTuple<Descriptor> boundHeapPath = replace(hpKey, argHeapPath, calleeParamHeapPath);
+          boundSet.put(boundHeapPath, curr.get(hpKey).clone());
+        }
+
+      }
+
+    }
+
+    // contribute callee's complete summary into the caller's current summary
+    ClearingSummary calleeCompleteSummary =
+        mapMethodDescriptorToCompleteClearingSummary.get(calleeFlatMethod.getMethod());
+
+    if (calleeCompleteSummary != null) {
+      ClearingSummary boundCalleeEfffects = new ClearingSummary();
+      for (int i = 0; i < calleeFlatMethod.numParameters(); i++) {
+        NTuple<Descriptor> argHeapPath = mapArgIdx2CallerArgHeapPath.get(Integer.valueOf(i));
+        TempDescriptor calleeParamHeapPath = mapParamIdx2ParamTempDesc.get(Integer.valueOf(i));
+
+        // iterate over callee's writing effect set
+        Set<NTuple<Descriptor>> hpKeySet = calleeCompleteSummary.keySet();
+        for (Iterator iterator = hpKeySet.iterator(); iterator.hasNext();) {
+          NTuple<Descriptor> hpKey = (NTuple<Descriptor>) iterator.next();
+          // current element is reachable caller's arg
+          // so need to bind it to the caller's side and add it to the callee's
+          // init summary
+          if (hpKey.startsWith(calleeParamHeapPath)) {
+
+            NTuple<Descriptor> boundHeapPathForCaller = replace(hpKey, argHeapPath);
+
+            boundCalleeEfffects.put(boundHeapPathForCaller, calleeCompleteSummary.get(hpKey)
+                .clone());
+
+          }
+        }
+      }
+      possibleCalleeCompleteSummarySetToCaller.add(boundCalleeEfffects);
+    }
+
+    return boundSet;
+  }
+
+  private NTuple<Descriptor> replace(NTuple<Descriptor> hpKey, NTuple<Descriptor> argHeapPath) {
+
+    // replace the head of heap path with caller's arg path
+    // for example, heap path 'param.a.b' in callee's side will be replaced with
+    // (corresponding arg heap path).a.b for caller's side
+
+    NTuple<Descriptor> bound = new NTuple<Descriptor>();
+
+    for (int i = 0; i < argHeapPath.size(); i++) {
+      bound.add(argHeapPath.get(i));
+    }
+
+    for (int i = 1; i < hpKey.size(); i++) {
+      bound.add(hpKey.get(i));
+    }
+
+    return bound;
+  }
+
+  private NTuple<Descriptor> replace(NTuple<Descriptor> effectHeapPath,
+      NTuple<Descriptor> argHeapPath, TempDescriptor calleeParamHeapPath) {
+    // replace the head of caller's heap path with callee's param heap path
+
+    NTuple<Descriptor> boundHeapPath = new NTuple<Descriptor>();
+    boundHeapPath.add(calleeParamHeapPath);
+
+    for (int i = argHeapPath.size(); i < effectHeapPath.size(); i++) {
+      boundHeapPath.add(effectHeapPath.get(i));
+    }
+
+    return boundHeapPath;
+  }
+
+  private void computeReadSharedDescriptorSet() {
+    Set<MethodDescriptor> methodDescriptorsToAnalyze = new HashSet<MethodDescriptor>();
+    methodDescriptorsToAnalyze.addAll(ssjava.getAnnotationRequireSet());
+
+    for (Iterator iterator = methodDescriptorsToAnalyze.iterator(); iterator.hasNext();) {
+      MethodDescriptor md = (MethodDescriptor) iterator.next();
+      FlatMethod fm = state.getMethodFlat(md);
+      computeReadSharedDescriptorSet_analyzeMethod(fm, md.equals(methodContainingSSJavaLoop));
+    }
+
+  }
+
+  private void computeReadSharedDescriptorSet_analyzeMethod(FlatMethod fm,
+      boolean onlyVisitSSJavaLoop) {
+
+    Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
+    Set<FlatNode> visited = new HashSet<FlatNode>();
+
+    if (onlyVisitSSJavaLoop) {
+      flatNodesToVisit.add(ssjavaLoopEntrance);
+    } else {
+      flatNodesToVisit.add(fm);
+    }
+
+    while (!flatNodesToVisit.isEmpty()) {
+      FlatNode fn = flatNodesToVisit.iterator().next();
+      flatNodesToVisit.remove(fn);
+      visited.add(fn);
+
+      computeReadSharedDescriptorSet_nodeActions(fn, onlyVisitSSJavaLoop);
+
+      for (int i = 0; i < fn.numNext(); i++) {
+        FlatNode nn = fn.getNext(i);
+        if (!visited.contains(nn)) {
+          if (!onlyVisitSSJavaLoop || (onlyVisitSSJavaLoop && loopIncElements.contains(nn))) {
+            flatNodesToVisit.add(nn);
+          }
+        }
+      }
+
+    }
+
+  }
+
+  private void computeReadSharedDescriptorSet_nodeActions(FlatNode fn, boolean isSSJavaLoop) {
+
+    TempDescriptor lhs;
+    TempDescriptor rhs;
+    FieldDescriptor fld;
+
+    switch (fn.kind()) {
+    case FKind.FlatOpNode: {
+      FlatOpNode fon = (FlatOpNode) fn;
+      lhs = fon.getDest();
+      rhs = fon.getLeft();
+
+      if (fon.getOp().getOp() == Operation.ASSIGN) {
+        if (rhs.getType().isImmutable() && isSSJavaLoop && (!rhs.getSymbol().startsWith("srctmp"))) {
+          // in ssjavaloop, we need to take care about reading local variables!
+          NTuple<Descriptor> rhsHeapPath = new NTuple<Descriptor>();
+          NTuple<Descriptor> lhsHeapPath = new NTuple<Descriptor>();
+          rhsHeapPath.add(LOCAL);
+          addReadDescriptor(rhsHeapPath, rhs);
+        }
+      }
+
+    }
+      break;
+
+    case FKind.FlatFieldNode:
+    case FKind.FlatElementNode: {
+
+      FlatFieldNode ffn = (FlatFieldNode) fn;
+      lhs = ffn.getDst();
+      rhs = ffn.getSrc();
+      fld = ffn.getField();
+
+      // read field
+      NTuple<Descriptor> srcHeapPath = mapHeapPath.get(rhs);
+      NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(srcHeapPath.getList());
+      // fldHeapPath.add(fld);
+
+      if (fld.getType().isImmutable()) {
+        addReadDescriptor(fldHeapPath, fld);
+      }
+
+      // propagate rhs's heap path to the lhs
+      mapHeapPath.put(lhs, fldHeapPath);
+
+    }
+      break;
+
+    case FKind.FlatSetFieldNode:
+    case FKind.FlatSetElementNode: {
+
+      FlatSetFieldNode fsfn = (FlatSetFieldNode) fn;
+      lhs = fsfn.getDst();
+      fld = fsfn.getField();
+
+      // write(field)
+      NTuple<Descriptor> lhsHeapPath = computePath(lhs);
+      NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(lhsHeapPath.getList());
+      // writeLocation(curr, fldHeapPath, fld, getLocation(fld));
+
+    }
+      break;
+
+    }
+  }
+
+  private boolean hasReadingEffectOnSharedLocation(NTuple<Descriptor> hp, Location loc, Descriptor d) {
+    if (!mapSharedLocation2DescriptorSet.containsKey(loc)) {
+      return false;
+    } else {
+      return mapSharedLocation2DescriptorSet.get(loc).contains(d);
+    }
+  }
+
+  private void addReadDescriptor(NTuple<Descriptor> hp, Descriptor d) {
+
+    Location loc = getLocation(d);
+
+    if (loc != null && ssjava.isSharedLocation(loc)) {
+
+      Set<Descriptor> set = mapSharedLocation2DescriptorSet.get(loc);
+      if (set == null) {
+        set = new HashSet<Descriptor>();
+        mapSharedLocation2DescriptorSet.put(loc, set);
+      }
+      set.add(d);
+    }
+
+  }
+
+  private Location getLocation(Descriptor d) {
+
+    if (d instanceof FieldDescriptor) {
+      return (Location) ((FieldDescriptor) d).getType().getExtension();
+    } else {
+      assert d instanceof TempDescriptor;
+      CompositeLocation comp = (CompositeLocation) ((TempDescriptor) d).getType().getExtension();
+      if (comp == null) {
+        return null;
+      } else {
+        return comp.get(comp.getSize() - 1);
+      }
+    }
+
+  }
+
+  private void writeLocation(ClearingSummary curr, NTuple<Descriptor> hp, Descriptor d) {
+    Location loc = getLocation(d);
+    if (loc != null && hasReadingEffectOnSharedLocation(hp, loc, d)) {
+
+      // 1. add field x to the clearing set
+      SharedStatus state = getState(curr, hp);
+      state.addVar(loc, d);
+
+      // 3. if the set v contains all of variables belonging to the shared
+      // location, set flag to true
+      Set<Descriptor> sharedVarSet = mapSharedLocation2DescriptorSet.get(loc);
+      if (state.getVarSet(loc).containsAll(sharedVarSet)) {
+        state.updateFlag(loc, true);
+      }
+    }
+  }
+
+  private void readLocation(ClearingSummary curr, NTuple<Descriptor> hp, Descriptor d) {
+    // remove reading var x from written set
+    Location loc = getLocation(d);
+    if (loc != null && hasReadingEffectOnSharedLocation(hp, loc, d)) {
+      SharedStatus state = getState(curr, hp);
+      state.removeVar(loc, d);
+    }
+  }
+
+  private SharedStatus getState(ClearingSummary curr, NTuple<Descriptor> hp) {
+    SharedStatus state = curr.get(hp);
+    if (state == null) {
+      state = new SharedStatus();
+      curr.put(hp, state);
+    }
+    return state;
+  }
+
+  private void writtenAnalyis() {
+    // perform second stage analysis: intraprocedural analysis ensure that
+    // all
+    // variables are definitely written in-between the same read
+
+    // First, identify ssjava loop entrace
+    FlatMethod fm = state.getMethodFlat(methodContainingSSJavaLoop);
+    Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
+    flatNodesToVisit.add(fm);
+
+    LoopFinder loopFinder = new LoopFinder(fm);
+
+    while (!flatNodesToVisit.isEmpty()) {
+      FlatNode fn = flatNodesToVisit.iterator().next();
+      flatNodesToVisit.remove(fn);
+
+      String label = (String) state.fn2labelMap.get(fn);
+      if (label != null) {
+
+        if (label.equals(ssjava.SSJAVA)) {
+          ssjavaLoopEntrance = fn;
+          break;
+        }
+      }
+
+      for (int i = 0; i < fn.numNext(); i++) {
+        FlatNode nn = fn.getNext(i);
+        flatNodesToVisit.add(nn);
+      }
+    }
+
+    assert ssjavaLoopEntrance != null;
+
+    // assume that ssjava loop is top-level loop in method, not nested loop
+    Set nestedLoop = loopFinder.nestedLoops();
+    for (Iterator loopIter = nestedLoop.iterator(); loopIter.hasNext();) {
+      LoopFinder lf = (LoopFinder) loopIter.next();
+      if (lf.loopEntrances().iterator().next().equals(ssjavaLoopEntrance)) {
+        ssjavaLoop = lf;
+      }
+    }
+
+    assert ssjavaLoop != null;
+
+    writtenAnalysis_analyzeLoop();
+
+  }
+
+  private void writtenAnalysis_analyzeLoop() {
+
+    Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
+    flatNodesToVisit.add(ssjavaLoopEntrance);
+
+    loopIncElements = (Set<FlatNode>) ssjavaLoop.loopIncElements();
+
+    while (!flatNodesToVisit.isEmpty()) {
+      FlatNode fn = (FlatNode) flatNodesToVisit.iterator().next();
+      flatNodesToVisit.remove(fn);
+
+      Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> prev =
+          definitelyWrittenResults.get(fn);
+
+      Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr =
+          new Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>>();
+      for (int i = 0; i < fn.numPrev(); i++) {
+        FlatNode nn = fn.getPrev(i);
+        Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> dwIn =
+            definitelyWrittenResults.get(nn);
+        if (dwIn != null) {
+          merge(curr, dwIn);
+        }
+      }
+
+      writtenAnalysis_nodeAction(fn, curr, ssjavaLoopEntrance);
+
+      // if a new result, schedule forward nodes for analysis
+      if (!curr.equals(prev)) {
+        definitelyWrittenResults.put(fn, curr);
+
+        for (int i = 0; i < fn.numNext(); i++) {
+          FlatNode nn = fn.getNext(i);
+          if (loopIncElements.contains(nn)) {
+            flatNodesToVisit.add(nn);
+          }
+
+        }
+      }
+    }
+  }
+
+  private void writtenAnalysis_nodeAction(FlatNode fn,
+      Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr, FlatNode loopEntrance) {
+
+    if (fn.equals(loopEntrance)) {
+      // it reaches loop entrance: changes all flag to true
+      Set<NTuple<Descriptor>> keySet = curr.keySet();
+      for (Iterator iterator = keySet.iterator(); iterator.hasNext();) {
+        NTuple<Descriptor> key = (NTuple<Descriptor>) iterator.next();
+        Hashtable<FlatNode, Boolean> pair = curr.get(key);
+        if (pair != null) {
+          Set<FlatNode> pairKeySet = pair.keySet();
+          for (Iterator iterator2 = pairKeySet.iterator(); iterator2.hasNext();) {
+            FlatNode pairKey = (FlatNode) iterator2.next();
+            pair.put(pairKey, Boolean.TRUE);
+          }
+        }
+      }
+    } else {
+      TempDescriptor lhs;
+      TempDescriptor rhs;
+      FieldDescriptor fld;
+
+      switch (fn.kind()) {
+      case FKind.FlatOpNode: {
+        FlatOpNode fon = (FlatOpNode) fn;
+        lhs = fon.getDest();
+        rhs = fon.getLeft();
+
+        NTuple<Descriptor> rhsHeapPath = computePath(rhs);
+        if (!rhs.getType().isImmutable()) {
+          mapHeapPath.put(lhs, rhsHeapPath);
+        } else {
+          if (fon.getOp().getOp() == Operation.ASSIGN) {
+            // read(rhs)
+            readValue(fn, rhsHeapPath, curr);
+          }
+          // write(lhs)
+          NTuple<Descriptor> lhsHeapPath = computePath(lhs);
+          removeHeapPath(curr, lhsHeapPath);
+        }
+      }
+        break;
+
+      case FKind.FlatLiteralNode: {
+        FlatLiteralNode fln = (FlatLiteralNode) fn;
+        lhs = fln.getDst();
+
+        // write(lhs)
+        NTuple<Descriptor> lhsHeapPath = computePath(lhs);
+        removeHeapPath(curr, lhsHeapPath);
+
+      }
+        break;
+
+      case FKind.FlatFieldNode:
+      case FKind.FlatElementNode: {
+
+        if (fn.kind() == FKind.FlatFieldNode) {
+          FlatFieldNode ffn = (FlatFieldNode) fn;
+          lhs = ffn.getDst();
+          rhs = ffn.getSrc();
+          fld = ffn.getField();
+        } else {
+          FlatElementNode fen = (FlatElementNode) fn;
+          lhs = fen.getDst();
+          rhs = fen.getSrc();
+          TypeDescriptor td = rhs.getType().dereference();
+          fld = getArrayField(td);
+        }
+
+        if (fld.isFinal() /* && fld.isStatic() */) {
+          // if field is final and static, no need to check
+          break;
+        }
+
+        // read field
+        NTuple<Descriptor> srcHeapPath = mapHeapPath.get(rhs);
+        NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(srcHeapPath.getList());
+        fldHeapPath.add(fld);
+
+        if (fld.getType().isImmutable()) {
+          readValue(fn, fldHeapPath, curr);
+        }
+
+        // propagate rhs's heap path to the lhs
+        mapHeapPath.put(lhs, fldHeapPath);
+
+      }
+        break;
+
+      case FKind.FlatSetFieldNode:
+      case FKind.FlatSetElementNode: {
+
+        if (fn.kind() == FKind.FlatSetFieldNode) {
+          FlatSetFieldNode fsfn = (FlatSetFieldNode) fn;
+          lhs = fsfn.getDst();
+          fld = fsfn.getField();
+        } else {
+          FlatSetElementNode fsen = (FlatSetElementNode) fn;
+          lhs = fsen.getDst();
+          rhs = fsen.getSrc();
+          TypeDescriptor td = lhs.getType().dereference();
+          fld = getArrayField(td);
+        }
+
+        // write(field)
+        NTuple<Descriptor> lhsHeapPath = computePath(lhs);
+        NTuple<Descriptor> fldHeapPath = new NTuple<Descriptor>(lhsHeapPath.getList());
+        fldHeapPath.add(fld);
+        removeHeapPath(curr, fldHeapPath);
+
+      }
+        break;
+
+      case FKind.FlatCall: {
+        FlatCall fc = (FlatCall) fn;
+        bindHeapPathCallerArgWithCaleeParam(fc);
+        // add <hp,statement,false> in which hp is an element of
+        // READ_bound set
+        // of callee: callee has 'read' requirement!
+
+        
+        for (Iterator iterator = calleeUnionBoundReadSet.iterator(); iterator.hasNext();) {
+          NTuple<Descriptor> read = (NTuple<Descriptor>) iterator.next();
+          Hashtable<FlatNode, Boolean> gen = curr.get(read);
+          if (gen == null) {
+            gen = new Hashtable<FlatNode, Boolean>();
+            curr.put(read, gen);
+          }
+          Boolean currentStatus = gen.get(fn);
+          if (currentStatus == null) {
+            gen.put(fn, Boolean.FALSE);
+          } else {
+            checkFlag(currentStatus.booleanValue(), fn, read);
+          }
+        }
+
+        // removes <hp,statement,flag> if hp is an element of
+        // OVERWRITE_bound
+        // set of callee. it means that callee will overwrite it
+        for (Iterator iterator = calleeIntersectBoundOverWriteSet.iterator(); iterator.hasNext();) {
+          NTuple<Descriptor> write = (NTuple<Descriptor>) iterator.next();
+          removeHeapPath(curr, write);
+        }
+      }
+        break;
+
+      }
+    }
+
+  }
+
+  private void readValue(FlatNode fn, NTuple<Descriptor> hp,
+      Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr) {
+    Hashtable<FlatNode, Boolean> gen = curr.get(hp);
+    if (gen == null) {
+      gen = new Hashtable<FlatNode, Boolean>();
+      curr.put(hp, gen);
+    }
+    Boolean currentStatus = gen.get(fn);
+    if (currentStatus == null) {
+      gen.put(fn, Boolean.FALSE);
+    } else {
+      checkFlag(currentStatus.booleanValue(), fn, hp);
+    }
+
+  }
+
+  private void removeHeapPath(Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr,
+      NTuple<Descriptor> hp) {
+
+    // removes all of heap path that starts with prefix 'hp'
+    // since any reference overwrite along heap path gives overwriting side
+    // effects on the value
+
+    Set<NTuple<Descriptor>> keySet = curr.keySet();
+    for (Iterator<NTuple<Descriptor>> iter = keySet.iterator(); iter.hasNext();) {
+      NTuple<Descriptor> key = iter.next();
+      if (key.startsWith(hp)) {
+        curr.put(key, new Hashtable<FlatNode, Boolean>());
+      }
+    }
+
+  }
+
+  private void bindHeapPathCallerArgWithCaleeParam(FlatCall fc) {
+    // compute all possible callee set
+    // transform all READ/OVERWRITE set from the any possible
+    // callees to the
+    // caller
+    calleeUnionBoundReadSet.clear();
+    calleeIntersectBoundOverWriteSet.clear();
+
+    MethodDescriptor mdCallee = fc.getMethod();
+    FlatMethod fmCallee = state.getMethodFlat(mdCallee);
+    Set<MethodDescriptor> setPossibleCallees = new HashSet<MethodDescriptor>();
+    TypeDescriptor typeDesc = fc.getThis().getType();
+    setPossibleCallees.addAll(callGraph.getMethods(mdCallee, typeDesc));
+
+    // create mapping from arg idx to its heap paths
+    Hashtable<Integer, NTuple<Descriptor>> mapArgIdx2CallerArgHeapPath =
+        new Hashtable<Integer, NTuple<Descriptor>>();
+
+    // arg idx is starting from 'this' arg
+    NTuple<Descriptor> thisHeapPath = mapHeapPath.get(fc.getThis());
+    if (thisHeapPath == null) {
+      // method is called without creating new flat node representing 'this'
+      thisHeapPath = new NTuple<Descriptor>();
+      thisHeapPath.add(fc.getThis());
+    }
+
+    mapArgIdx2CallerArgHeapPath.put(Integer.valueOf(0), thisHeapPath);
+
+    for (int i = 0; i < fc.numArgs(); i++) {
+      TempDescriptor arg = fc.getArg(i);
+      NTuple<Descriptor> argHeapPath = computePath(arg);
+      mapArgIdx2CallerArgHeapPath.put(Integer.valueOf(i + 1), argHeapPath);
+    }
+
+    for (Iterator iterator = setPossibleCallees.iterator(); iterator.hasNext();) {
+      MethodDescriptor callee = (MethodDescriptor) iterator.next();
+      FlatMethod calleeFlatMethod = state.getMethodFlat(callee);
+
+      // binding caller's args and callee's params
+
+      Set<NTuple<Descriptor>> calleeReadSet = mapFlatMethodToRead.get(calleeFlatMethod);
+      if (calleeReadSet == null) {
+        calleeReadSet = new HashSet<NTuple<Descriptor>>();
+        mapFlatMethodToRead.put(calleeFlatMethod, calleeReadSet);
+      }
+      Set<NTuple<Descriptor>> calleeOverWriteSet = mapFlatMethodToOverWrite.get(calleeFlatMethod);
+      if (calleeOverWriteSet == null) {
+        calleeOverWriteSet = new HashSet<NTuple<Descriptor>>();
+        mapFlatMethodToOverWrite.put(calleeFlatMethod, calleeOverWriteSet);
+      }
+
+      Hashtable<Integer, TempDescriptor> mapParamIdx2ParamTempDesc =
+          new Hashtable<Integer, TempDescriptor>();
+      for (int i = 0; i < calleeFlatMethod.numParameters(); i++) {
+        TempDescriptor param = calleeFlatMethod.getParameter(i);
+        mapParamIdx2ParamTempDesc.put(Integer.valueOf(i), param);
+      }
+
+      Set<NTuple<Descriptor>> calleeBoundReadSet =
+          bindSet(calleeReadSet, mapParamIdx2ParamTempDesc, mapArgIdx2CallerArgHeapPath);
+      // union of the current read set and the current callee's
+      // read set
+      calleeUnionBoundReadSet.addAll(calleeBoundReadSet);
+      Set<NTuple<Descriptor>> calleeBoundWriteSet =
+          bindSet(calleeOverWriteSet, mapParamIdx2ParamTempDesc, mapArgIdx2CallerArgHeapPath);
+      // intersection of the current overwrite set and the current
+      // callee's
+      // overwrite set
+      merge(calleeIntersectBoundOverWriteSet, calleeBoundWriteSet);
+    }
+
+  }
+
+  private void checkFlag(boolean booleanValue, FlatNode fn, NTuple<Descriptor> hp) {
+    if (booleanValue) {
+      throw new Error(
+          "There is a variable, which is reachable through references "
+              + hp
+              + ", who comes back to the same read statement without being overwritten at the out-most iteration at "
+              + methodContainingSSJavaLoop.getClassDesc().getSourceFileName() + "::"
+              + fn.getNumLine());
+    }
+  }
+
+  private void merge(Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> curr,
+      Hashtable<NTuple<Descriptor>, Hashtable<FlatNode, Boolean>> in) {
+
+    Set<NTuple<Descriptor>> inKeySet = in.keySet();
+    for (Iterator iterator = inKeySet.iterator(); iterator.hasNext();) {
+      NTuple<Descriptor> inKey = (NTuple<Descriptor>) iterator.next();
+      Hashtable<FlatNode, Boolean> inPair = in.get(inKey);
+
+      Set<FlatNode> pairKeySet = inPair.keySet();
+      for (Iterator iterator2 = pairKeySet.iterator(); iterator2.hasNext();) {
+        FlatNode pairKey = (FlatNode) iterator2.next();
+        Boolean inFlag = inPair.get(pairKey);
+
+        Hashtable<FlatNode, Boolean> currPair = curr.get(inKey);
+        if (currPair == null) {
+          currPair = new Hashtable<FlatNode, Boolean>();
+          curr.put(inKey, currPair);
+        }
+
+        Boolean currFlag = currPair.get(pairKey);
+        // by default, flag is set by false
+        if (currFlag == null) {
+          currFlag = Boolean.FALSE;
+        }
+        currFlag = Boolean.valueOf(inFlag.booleanValue() | currFlag.booleanValue());
+        currPair.put(pairKey, currFlag);
+      }
+
+    }
+
+  }
+
+  private void methodReadOverWriteAnalysis() {
+    // perform method READ/OVERWRITE analysis
+    Set<MethodDescriptor> methodDescriptorsToAnalyze = new HashSet<MethodDescriptor>();
+    methodDescriptorsToAnalyze.addAll(ssjava.getAnnotationRequireSet());
+
+    sortedDescriptors = topologicalSort(methodDescriptorsToAnalyze);
+
+    LinkedList<MethodDescriptor> descriptorListToAnalyze =
+        (LinkedList<MethodDescriptor>) sortedDescriptors.clone();
+
+    // no need to analyze method having ssjava loop
+    // methodContainingSSJavaLoop = descriptorListToAnalyze.removeFirst();
+    methodContainingSSJavaLoop = ssjava.getMethodContainingSSJavaLoop();
+
+    // current descriptors to visit in fixed-point interprocedural analysis,
+    // prioritized by
+    // dependency in the call graph
+    methodDescriptorsToVisitStack.clear();
+
+    Set<MethodDescriptor> methodDescriptorToVistSet = new HashSet<MethodDescriptor>();
+    methodDescriptorToVistSet.addAll(descriptorListToAnalyze);
+
+    while (!descriptorListToAnalyze.isEmpty()) {
+      MethodDescriptor md = descriptorListToAnalyze.removeFirst();
+      methodDescriptorsToVisitStack.add(md);
+    }
+
+    // analyze scheduled methods until there are no more to visit
+    while (!methodDescriptorsToVisitStack.isEmpty()) {
+      // start to analyze leaf node
+      MethodDescriptor md = methodDescriptorsToVisitStack.pop();
+      FlatMethod fm = state.getMethodFlat(md);
+
+      Set<NTuple<Descriptor>> readSet = new HashSet<NTuple<Descriptor>>();
+      Set<NTuple<Descriptor>> overWriteSet = new HashSet<NTuple<Descriptor>>();
+
+      methodReadOverWrite_analyzeMethod(fm, readSet, overWriteSet);
+
+      Set<NTuple<Descriptor>> prevRead = mapFlatMethodToRead.get(fm);
+      Set<NTuple<Descriptor>> prevOverWrite = mapFlatMethodToOverWrite.get(fm);
+
+      if (!(readSet.equals(prevRead) && overWriteSet.equals(prevOverWrite))) {
+        mapFlatMethodToRead.put(fm, readSet);
+        mapFlatMethodToOverWrite.put(fm, overWriteSet);
+
+        // results for callee changed, so enqueue dependents caller for
+        // further
+        // analysis
+        Iterator<MethodDescriptor> depsItr = getDependents(md).iterator();
+        while (depsItr.hasNext()) {
+          MethodDescriptor methodNext = depsItr.next();
+          if (!methodDescriptorsToVisitStack.contains(methodNext)
+              && methodDescriptorToVistSet.contains(methodNext)) {
+            methodDescriptorsToVisitStack.add(methodNext);
+          }
+
+        }
+
+      }
+
+    }
+
+  }
+
+  private void methodReadOverWrite_analyzeMethod(FlatMethod fm, Set<NTuple<Descriptor>> readSet,
+      Set<NTuple<Descriptor>> overWriteSet) {
+    if (state.SSJAVADEBUG) {
+      System.out.println("Definitely written Analyzing: " + fm);
+    }
+
+    // intraprocedural analysis
+    Set<FlatNode> flatNodesToVisit = new HashSet<FlatNode>();
+    flatNodesToVisit.add(fm);
+
+    while (!flatNodesToVisit.isEmpty()) {
+      FlatNode fn = flatNodesToVisit.iterator().next();
+      flatNodesToVisit.remove(fn);
+
+      Set<NTuple<Descriptor>> curr = new HashSet<NTuple<Descriptor>>();
+
+      for (int i = 0; i < fn.numPrev(); i++) {
+        FlatNode prevFn = fn.getPrev(i);
+        Set<NTuple<Descriptor>> in = mapFlatNodeToWrittenSet.get(prevFn);
+        if (in != null) {
+          merge(curr, in);
+        }
+      }
+
+      methodReadOverWrite_nodeActions(fn, curr, readSet, overWriteSet);
+
+      Set<NTuple<Descriptor>> writtenSetPrev = mapFlatNodeToWrittenSet.get(fn);
+      if (!curr.equals(writtenSetPrev)) {
+        mapFlatNodeToWrittenSet.put(fn, curr);
+        for (int i = 0; i < fn.numNext(); i++) {
+          FlatNode nn = fn.getNext(i);
+          flatNodesToVisit.add(nn);
+        }
+      }
+
+    }
+
+  }
+
+  private void methodReadOverWrite_nodeActions(FlatNode fn, Set<NTuple<Descriptor>> writtenSet,
+      Set<NTuple<Descriptor>> readSet, Set<NTuple<Descriptor>> overWriteSet) {
+    TempDescriptor lhs;
+    TempDescriptor rhs;
+    FieldDescriptor fld;
+
+    switch (fn.kind()) {
+    case FKind.FlatMethod: {
+
+      // set up initial heap paths for method parameters
+      FlatMethod fm = (FlatMethod) fn;
+      for (int i = 0; i < fm.numParameters(); i++) {
+        TempDescriptor param = fm.getParameter(i);
+        NTuple<Descriptor> heapPath = new NTuple<Descriptor>();
+        heapPath.add(param);
+        mapHeapPath.put(param, heapPath);
+      }
+    }
+      break;
+
+    case FKind.FlatOpNode: {
+      FlatOpNode fon = (FlatOpNode) fn;
+      // for a normal assign node, need to propagate lhs's heap path to
+      // rhs
+      if (fon.getOp().getOp() == Operation.ASSIGN) {
+        rhs = fon.getLeft();
+        lhs = fon.getDest();
+
+        NTuple<Descriptor> rhsHeapPath = mapHeapPath.get(rhs);
+        if (rhsHeapPath != null) {
+          mapHeapPath.put(lhs, mapHeapPath.get(rhs));
+        }
+
+      }
+    }
+      break;
+
+    case FKind.FlatElementNode:
+    case FKind.FlatFieldNode: {
+
+      // y=x.f;
+
+      if (fn.kind() == FKind.FlatFieldNode) {
+        FlatFieldNode ffn = (FlatFieldNode) fn;
+        lhs = ffn.getDst();
+        rhs = ffn.getSrc();
+        fld = ffn.getField();
+      } else {
+        FlatElementNode fen = (FlatElementNode) fn;
+        lhs = fen.getDst();
+        rhs = fen.getSrc();
+        TypeDescriptor td = rhs.getType().dereference();
+        fld = getArrayField(td);
+      }
+
+      if (fld.isFinal() /* && fld.isStatic() */) {
+        // if field is final and static, no need to check
+        break;
+      }
+
+      // set up heap path
+      NTuple<Descriptor> srcHeapPath = mapHeapPath.get(rhs);
+      if (srcHeapPath != null) {
+        // if lhs srcHeapPath is null, it means that it is not reachable from
+        // callee's parameters. so just ignore it
+
+        NTuple<Descriptor> readingHeapPath = new NTuple<Descriptor>(srcHeapPath.getList());
+        readingHeapPath.add(fld);
+        mapHeapPath.put(lhs, readingHeapPath);
+
+        // read (x.f)
+        if (fld.getType().isImmutable()) {
+          // if WT doesnot have hp(x.f), add hp(x.f) to READ
+          if (!writtenSet.contains(readingHeapPath)) {
+            readSet.add(readingHeapPath);
+          }
+        }
+
+        //no need to kill hp(x.f) from WT
+      }
+
+    }
+      break;
+
+    case FKind.FlatSetFieldNode:
+    case FKind.FlatSetElementNode: {
+
+      // x.f=y;
+
+      if (fn.kind() == FKind.FlatSetFieldNode) {
+        FlatSetFieldNode fsfn = (FlatSetFieldNode) fn;
+        lhs = fsfn.getDst();
+        fld = fsfn.getField();
+        rhs = fsfn.getSrc();
+      } else {
+        FlatSetElementNode fsen = (FlatSetElementNode) fn;
+        lhs = fsen.getDst();
+        rhs = fsen.getSrc();
+        TypeDescriptor td = lhs.getType().dereference();
+        fld = getArrayField(td);
+      }
+
+      // set up heap path
+      NTuple<Descriptor> lhsHeapPath = mapHeapPath.get(lhs);
+      if (lhsHeapPath != null) {
+        // if lhs heap path is null, it means that it is not reachable from
+        // callee's parameters. so just ignore it
+        NTuple<Descriptor> newHeapPath = new NTuple<Descriptor>(lhsHeapPath.getList());
+        newHeapPath.add(fld);
+        mapHeapPath.put(fld, newHeapPath);
+
+        // write(x.f)
+        // need to add hp(y) to WT
+        writtenSet.add(newHeapPath);
+      }
+
+    }
+      break;
+
+    case FKind.FlatCall: {
+
+      FlatCall fc = (FlatCall) fn;
+
+      if (fc.getThis() != null) {
+        bindHeapPathCallerArgWithCaleeParam(fc);
+        
+        // add heap path, which is an element of READ_bound set and is not
+        // an
+        // element of WT set, to the caller's READ set
+        for (Iterator iterator = calleeUnionBoundReadSet.iterator(); iterator.hasNext();) {
+          NTuple<Descriptor> read = (NTuple<Descriptor>) iterator.next();
+          if (!writtenSet.contains(read)) {
+            readSet.add(read);
+          }
+        }
+
+        // add heap path, which is an element of OVERWRITE_bound set, to the
+        // caller's WT set
+        for (Iterator iterator = calleeIntersectBoundOverWriteSet.iterator(); iterator.hasNext();) {
+          NTuple<Descriptor> write = (NTuple<Descriptor>) iterator.next();
+          writtenSet.add(write);
+        }
+      } 
+
+    }
+      break;
+
+    case FKind.FlatExit: {
+      // merge the current written set with OVERWRITE set
+      merge(overWriteSet, writtenSet);
+    }
+      break;
+
+    }
+
+  }
+
+  static public FieldDescriptor getArrayField(TypeDescriptor td) {
+    FieldDescriptor fd = mapTypeToArrayField.get(td);
+    if (fd == null) {
+      fd =
+          new FieldDescriptor(new Modifiers(Modifiers.PUBLIC), td, arrayElementFieldName, null,
+              false);
+      mapTypeToArrayField.put(td, fd);
+    }
+    return fd;
+  }
+
+  private void mergeSharedLocationAnaylsis(ClearingSummary curr, Set<ClearingSummary> inSet) {
+
+    if (inSet.size() == 0) {
+      return;
+    }
+
+    Hashtable<Pair<NTuple<Descriptor>, Location>, Boolean> mapHeapPathLoc2Flag =
+        new Hashtable<Pair<NTuple<Descriptor>, Location>, Boolean>();
+
+    for (Iterator inIterator = inSet.iterator(); inIterator.hasNext();) {
+
+      ClearingSummary inTable = (ClearingSummary) inIterator.next();
+
+      Set<NTuple<Descriptor>> keySet = inTable.keySet();
+
+      for (Iterator iterator = keySet.iterator(); iterator.hasNext();) {
+        NTuple<Descriptor> hpKey = (NTuple<Descriptor>) iterator.next();
+        SharedStatus inState = inTable.get(hpKey);
+
+        SharedStatus currState = curr.get(hpKey);
+        if (currState == null) {
+          currState = new SharedStatus();
+          curr.put(hpKey, currState);
+        }
+        currState.merge(inState);
+
+        Set<Location> locSet = inState.getMap().keySet();
+        for (Iterator iterator2 = locSet.iterator(); iterator2.hasNext();) {
+          Location loc = (Location) iterator2.next();
+          Pair<Set<Descriptor>, Boolean> pair = inState.getMap().get(loc);
+          boolean inFlag = pair.getSecond().booleanValue();
+
+          Pair<NTuple<Descriptor>, Location> flagKey =
+              new Pair<NTuple<Descriptor>, Location>(hpKey, loc);
+          Boolean current = mapHeapPathLoc2Flag.get(flagKey);
+          if (current == null) {
+            current = new Boolean(true);
+          }
+          boolean newInFlag = current.booleanValue() & inFlag;
+          mapHeapPathLoc2Flag.put(flagKey, Boolean.valueOf(newInFlag));
+        }
+
+      }
+
+    }
+
+    // merge flag status
+    Set<NTuple<Descriptor>> hpKeySet = curr.keySet();
+    for (Iterator iterator = hpKeySet.iterator(); iterator.hasNext();) {
+      NTuple<Descriptor> hpKey = (NTuple<Descriptor>) iterator.next();
+      SharedStatus currState = curr.get(hpKey);
+      Set<Location> locKeySet = currState.getMap().keySet();
+      for (Iterator iterator2 = locKeySet.iterator(); iterator2.hasNext();) {
+        Location locKey = (Location) iterator2.next();
+        Pair<Set<Descriptor>, Boolean> pair = currState.getMap().get(locKey);
+        boolean currentFlag = pair.getSecond().booleanValue();
+        Boolean inFlag = mapHeapPathLoc2Flag.get(new Pair(hpKey, locKey));
+        if (inFlag != null) {
+          boolean newFlag = currentFlag | inFlag.booleanValue();
+          if (currentFlag != newFlag) {
+            currState.getMap().put(locKey, new Pair(pair.getFirst(), new Boolean(newFlag)));
+          }
+        }
+      }
+    }
+
+  }
+
+  private void merge(Set<NTuple<Descriptor>> curr, Set<NTuple<Descriptor>> in) {
+    if (curr.isEmpty()) {
+      // WrittenSet has a special initial value which covers all possible
+      // elements
+      // For the first time of intersection, we can take all previous set
+      curr.addAll(in);
+    } else {
+      // otherwise, current set is the intersection of the two sets
+      curr.retainAll(in);
+    }
+
+  }
+
+  // combine two heap path
+  private NTuple<Descriptor> combine(NTuple<Descriptor> callerIn, NTuple<Descriptor> calleeIn) {
+    NTuple<Descriptor> combined = new NTuple<Descriptor>();
+
+    for (int i = 0; i < callerIn.size(); i++) {
+      combined.add(callerIn.get(i));
+    }
+
+    // the first element of callee's heap path represents parameter
+    // so we skip the first one since it is already added from caller's heap
+    // path
+    for (int i = 1; i < calleeIn.size(); i++) {
+      combined.add(calleeIn.get(i));
+    }
+
+    return combined;
+  }
+
+  private Set<NTuple<Descriptor>> bindSet(Set<NTuple<Descriptor>> calleeSet,
+      Hashtable<Integer, TempDescriptor> mapParamIdx2ParamTempDesc,
+      Hashtable<Integer, NTuple<Descriptor>> mapCallerArgIdx2HeapPath) {
+
+    Set<NTuple<Descriptor>> boundedCalleeSet = new HashSet<NTuple<Descriptor>>();
+
+    Set<Integer> keySet = mapCallerArgIdx2HeapPath.keySet();
+    for (Iterator iterator = keySet.iterator(); iterator.hasNext();) {
+      Integer idx = (Integer) iterator.next();
+
+      NTuple<Descriptor> callerArgHeapPath = mapCallerArgIdx2HeapPath.get(idx);
+      TempDescriptor calleeParam = mapParamIdx2ParamTempDesc.get(idx);
+
+      for (Iterator iterator2 = calleeSet.iterator(); iterator2.hasNext();) {
+        NTuple<Descriptor> element = (NTuple<Descriptor>) iterator2.next();
+        if (element.startsWith(calleeParam)) {
+          NTuple<Descriptor> boundElement = combine(callerArgHeapPath, element);
+          boundedCalleeSet.add(boundElement);
+        }
+
+      }
+
+    }
+    return boundedCalleeSet;
+
+  }
+
+  // Borrowed it from disjoint analysis
+  private LinkedList<MethodDescriptor> topologicalSort(Set<MethodDescriptor> toSort) {
+
+    Set<MethodDescriptor> discovered = new HashSet<MethodDescriptor>();
+
+    LinkedList<MethodDescriptor> sorted = new LinkedList<MethodDescriptor>();
+
+    Iterator<MethodDescriptor> itr = toSort.iterator();
+    while (itr.hasNext()) {
+      MethodDescriptor d = itr.next();
+
+      if (!discovered.contains(d)) {
+        dfsVisit(d, toSort, sorted, discovered);
+      }
+    }
+
+    return sorted;
+  }
+
+  // While we're doing DFS on call graph, remember
+  // dependencies for efficient queuing of methods
+  // during interprocedural analysis:
+  //
+  // a dependent of a method decriptor d for this analysis is:
+  // 1) a method or task that invokes d
+  // 2) in the descriptorsToAnalyze set
+  private void dfsVisit(MethodDescriptor md, Set<MethodDescriptor> toSort,
+      LinkedList<MethodDescriptor> sorted, Set<MethodDescriptor> discovered) {
+
+    discovered.add(md);
+
+    Iterator itr = callGraph.getCallerSet(md).iterator();
+    while (itr.hasNext()) {
+      MethodDescriptor dCaller = (MethodDescriptor) itr.next();
+      // only consider callers in the original set to analyze
+      if (!toSort.contains(dCaller)) {
+        continue;
+      }
+      if (!discovered.contains(dCaller)) {
+        addDependent(md, // callee
+            dCaller // caller
+        );
+
+        dfsVisit(dCaller, toSort, sorted, discovered);
+      }
+    }
+
+    // for leaf-nodes last now!
+    sorted.addLast(md);
+  }
+
+  // a dependent of a method decriptor d for this analysis is:
+  // 1) a method or task that invokes d
+  // 2) in the descriptorsToAnalyze set
+  private void addDependent(MethodDescriptor callee, MethodDescriptor caller) {
+    Set<MethodDescriptor> deps = mapDescriptorToSetDependents.get(callee);
+    if (deps == null) {
+      deps = new HashSet<MethodDescriptor>();
+    }
+    deps.add(caller);
+    mapDescriptorToSetDependents.put(callee, deps);
+  }
+
+  private Set<MethodDescriptor> getDependents(MethodDescriptor callee) {
+    Set<MethodDescriptor> deps = mapDescriptorToSetDependents.get(callee);
+    if (deps == null) {
+      deps = new HashSet<MethodDescriptor>();
+      mapDescriptorToSetDependents.put(callee, deps);
+    }
+    return deps;
+  }
+
+  private NTuple<Descriptor> computePath(TempDescriptor td) {
+    // generate proper path fot input td
+    // if td is local variable, it just generate one element tuple path
+    if (mapHeapPath.containsKey(td)) {
+      return mapHeapPath.get(td);
+    } else {
+      NTuple<Descriptor> path = new NTuple<Descriptor>();
+      path.add(td);
+      return path;
+    }
+  }
 
 }
\ No newline at end of file