X-Git-Url: http://plrg.eecs.uci.edu/git/?a=blobdiff_plain;ds=sidebyside;f=Robust%2Fsrc%2FAnalysis%2FSSJava%2FSSJavaAnalysis.java;h=121e4cb5fb135c56122f1f6dfbf25f0fbf72f017;hb=d396c42d2a86460c7e220d21e5219049c177c5cf;hp=58cb3babf8c0a7cd8a67c581378e67a785c68d21;hpb=e5b2a0989e82014b8cec2ef1d7044457f04fd4df;p=IRC.git

diff --git a/Robust/src/Analysis/SSJava/SSJavaAnalysis.java b/Robust/src/Analysis/SSJava/SSJavaAnalysis.java
index 58cb3bab..121e4cb5 100644
--- a/Robust/src/Analysis/SSJava/SSJavaAnalysis.java
+++ b/Robust/src/Analysis/SSJava/SSJavaAnalysis.java
@@ -1,26 +1,65 @@
 package Analysis.SSJava;
 
+import java.io.BufferedWriter;
+import java.io.FileWriter;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashSet;
 import java.util.Hashtable;
 import java.util.Iterator;
+import java.util.LinkedList;
+import java.util.List;
 import java.util.Set;
 import java.util.StringTokenizer;
 import java.util.Vector;
 
+import Analysis.CallGraph.CallGraph;
+import Analysis.Loops.GlobalFieldType;
+import Analysis.Loops.LoopFinder;
+import Analysis.Loops.LoopOptimize;
+import Analysis.Loops.LoopTerminate;
 import IR.AnnotationDescriptor;
 import IR.ClassDescriptor;
+import IR.Descriptor;
+import IR.FieldDescriptor;
 import IR.MethodDescriptor;
 import IR.State;
+import IR.SymbolTable;
+import IR.TypeUtil;
+import IR.Flat.BuildFlat;
+import IR.Flat.FlatMethod;
+import IR.Flat.FlatNode;
+import Util.Pair;
 
 public class SSJavaAnalysis {
 
+  public static final String SSJAVA = "SSJAVA";
   public static final String LATTICE = "LATTICE";
   public static final String METHODDEFAULT = "METHODDEFAULT";
   public static final String THISLOC = "THISLOC";
   public static final String GLOBALLOC = "GLOBALLOC";
+  public static final String RETURNLOC = "RETURNLOC";
+  public static final String PCLOC = "PCLOC";
   public static final String LOC = "LOC";
-  public static final String DELTA = "delta";
+  public static final String DELTA = "DELTA";
+  public static final String TERMINATE = "TERMINATE";
+  public static final String DELEGATE = "DELEGATE";
+  public static final String DELEGATETHIS = "DELEGATETHIS";
+  public static final String TRUST = "TRUST";
+
+  public static final String TOP = "_top_";
+  public static final String BOTTOM = "_bottom_";
+
   State state;
+  TypeUtil tu;
   FlowDownCheck flowDownChecker;
+  MethodAnnotationCheck methodAnnotationChecker;
+  BuildFlat bf;
+
+  // set containing method requires to be annoated
+  Set<MethodDescriptor> annotationRequireSet;
 
   // class -> field lattice
   Hashtable<ClassDescriptor, SSJavaLattice<String>> cd2lattice;
@@ -31,17 +70,194 @@ public class SSJavaAnalysis {
   // method -> local variable lattice
   Hashtable<MethodDescriptor, MethodLattice<String>> md2lattice;
 
-  public SSJavaAnalysis(State state) {
+  // method set that does not want to have loop termination analysis
+  Hashtable<MethodDescriptor, Integer> skipLoopTerminate;
+
+  // map shared location to its descriptors
+  Hashtable<Location, Set<Descriptor>> mapSharedLocation2DescriptorSet;
+
+  // set containing a class that has at least one annoated method
+  Set<ClassDescriptor> annotationRequireClassSet;
+
+  // the set of method descriptor required to check the linear type property
+  Set<MethodDescriptor> linearTypeCheckMethodSet;
+
+  // the set of method descriptors annotated as "TRUST"
+  Set<MethodDescriptor> trustWorthyMDSet;
+
+  // points to method containing SSJAVA Loop
+  private MethodDescriptor methodContainingSSJavaLoop;
+
+  private FlatNode ssjavaLoopEntrance;
+
+  // keep the field ownership from the linear type checking
+  Hashtable<MethodDescriptor, Set<FieldDescriptor>> mapMethodToOwnedFieldSet;
+
+  Set<FlatNode> sameHeightWriteFlatNodeSet;
+
+  CallGraph callgraph;
+
+  LinearTypeCheck checker;
+
+  // 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;
+
+  private LinkedList<MethodDescriptor> sortedDescriptors;
+
+  public SSJavaAnalysis(State state, TypeUtil tu, BuildFlat bf, CallGraph callgraph) {
     this.state = state;
-    cd2lattice = new Hashtable<ClassDescriptor, SSJavaLattice<String>>();
-    cd2methodDefault = new Hashtable<ClassDescriptor, MethodLattice<String>>();
-    md2lattice = new Hashtable<MethodDescriptor, MethodLattice<String>>();
+    this.tu = tu;
+    this.callgraph = callgraph;
+    this.cd2lattice = new Hashtable<ClassDescriptor, SSJavaLattice<String>>();
+    this.cd2methodDefault = new Hashtable<ClassDescriptor, MethodLattice<String>>();
+    this.md2lattice = new Hashtable<MethodDescriptor, MethodLattice<String>>();
+    this.annotationRequireSet = new HashSet<MethodDescriptor>();
+    this.annotationRequireClassSet = new HashSet<ClassDescriptor>();
+    this.skipLoopTerminate = new Hashtable<MethodDescriptor, Integer>();
+    this.mapSharedLocation2DescriptorSet = new Hashtable<Location, Set<Descriptor>>();
+    this.linearTypeCheckMethodSet = new HashSet<MethodDescriptor>();
+    this.bf = bf;
+    this.trustWorthyMDSet = new HashSet<MethodDescriptor>();
+    this.mapMethodToOwnedFieldSet = new Hashtable<MethodDescriptor, Set<FieldDescriptor>>();
+    this.sameHeightWriteFlatNodeSet = new HashSet<FlatNode>();
+    this.mapDescriptorToSetDependents = new Hashtable<Descriptor, Set<MethodDescriptor>>();
+    this.sortedDescriptors = new LinkedList<MethodDescriptor>();
   }
 
   public void doCheck() {
-    parseLocationAnnotation();
-    doFlowDownCheck();
-    doLoopCheck();
+    doMethodAnnotationCheck();
+    computeLinearTypeCheckMethodSet();
+    doLinearTypeCheck();
+
+    init();
+
+    if (state.SSJAVADEBUG) {
+      debug_printAnnotationRequiredSet();
+    }
+    if (state.SSJAVAINFER) {
+      inference();
+    } else {
+      parseLocationAnnotation();
+      doFlowDownCheck();
+      doDefinitelyWrittenCheck();
+      doLoopCheck();
+    }
+  }
+
+  private void init() {
+    // perform topological sort over the set of methods accessed by the main
+    // event loop
+    Set<MethodDescriptor> methodDescriptorsToAnalyze = new HashSet<MethodDescriptor>();
+    methodDescriptorsToAnalyze.addAll(getAnnotationRequireSet());
+    sortedDescriptors = topologicalSort(methodDescriptorsToAnalyze);
+  }
+
+  public LinkedList<MethodDescriptor> getSortedDescriptors() {
+    return (LinkedList<MethodDescriptor>) sortedDescriptors.clone();
+  }
+
+  private void inference() {
+    LocationInference inferEngine = new LocationInference(this, state);
+    inferEngine.inference();
+  }
+
+  private void doLoopCheck() {
+    GlobalFieldType gft = new GlobalFieldType(callgraph, state, tu.getMain());
+    LoopOptimize lo = new LoopOptimize(gft, tu);
+
+    SymbolTable classtable = state.getClassSymbolTable();
+
+    List<ClassDescriptor> toanalyzeList = new ArrayList<ClassDescriptor>();
+    List<MethodDescriptor> toanalyzeMethodList = new ArrayList<MethodDescriptor>();
+
+    toanalyzeList.addAll(classtable.getValueSet());
+    Collections.sort(toanalyzeList, new Comparator<ClassDescriptor>() {
+      public int compare(ClassDescriptor o1, ClassDescriptor o2) {
+        return o1.getClassName().compareTo(o2.getClassName());
+      }
+    });
+
+    for (int i = 0; i < toanalyzeList.size(); i++) {
+      ClassDescriptor cd = toanalyzeList.get(i);
+
+      SymbolTable methodtable = cd.getMethodTable();
+      toanalyzeMethodList.clear();
+      toanalyzeMethodList.addAll(methodtable.getValueSet());
+      Collections.sort(toanalyzeMethodList, new Comparator<MethodDescriptor>() {
+        public int compare(MethodDescriptor o1, MethodDescriptor o2) {
+          return o1.getSymbol().compareTo(o2.getSymbol());
+        }
+      });
+
+      for (int mdIdx = 0; mdIdx < toanalyzeMethodList.size(); mdIdx++) {
+        MethodDescriptor md = toanalyzeMethodList.get(mdIdx);
+        if (needTobeAnnotated(md)) {
+          lo.analyze(state.getMethodFlat(md));
+          doLoopTerminationCheck(lo, state.getMethodFlat(md));
+        }
+      }
+
+    }
+
+  }
+
+  public void addTrustMethod(MethodDescriptor md) {
+    trustWorthyMDSet.add(md);
+  }
+
+  public boolean isTrustMethod(MethodDescriptor md) {
+    return trustWorthyMDSet.contains(md);
+  }
+
+  private void computeLinearTypeCheckMethodSet() {
+
+    Set<MethodDescriptor> allCalledSet = callgraph.getMethodCalls(tu.getMain());
+    linearTypeCheckMethodSet.addAll(allCalledSet);
+
+    Set<MethodDescriptor> trustedSet = new HashSet<MethodDescriptor>();
+
+    for (Iterator iterator = trustWorthyMDSet.iterator(); iterator.hasNext();) {
+      MethodDescriptor trustMethod = (MethodDescriptor) iterator.next();
+      Set<MethodDescriptor> calledFromTrustMethodSet = callgraph.getMethodCalls(trustMethod);
+      trustedSet.add(trustMethod);
+      trustedSet.addAll(calledFromTrustMethodSet);
+    }
+
+    linearTypeCheckMethodSet.removeAll(trustedSet);
+
+    // if a method is called only by trusted method, no need to check linear
+    // type & flow down rule
+    for (Iterator iterator = trustedSet.iterator(); iterator.hasNext();) {
+      MethodDescriptor md = (MethodDescriptor) iterator.next();
+      Set<MethodDescriptor> callerSet = callgraph.getCallerSet(md);
+      if (!trustedSet.containsAll(callerSet) && !trustWorthyMDSet.contains(md)) {
+        linearTypeCheckMethodSet.add(md);
+      }
+    }
+
+  }
+
+  private void doLinearTypeCheck() {
+    LinearTypeCheck checker = new LinearTypeCheck(this, state);
+    checker.linearTypeCheck();
+  }
+
+  public void debug_printAnnotationRequiredSet() {
+    System.out.println("SSJAVA: SSJava is checking the following methods:");
+    for (Iterator<MethodDescriptor> iterator = annotationRequireSet.iterator(); iterator.hasNext();) {
+      MethodDescriptor md = iterator.next();
+      System.out.println(md);
+    }
+    System.out.println();
+  }
+
+  private void doMethodAnnotationCheck() {
+    methodAnnotationChecker = new MethodAnnotationCheck(this, state, tu);
+    methodAnnotationChecker.methodAnnoatationCheck();
+    methodAnnotationChecker.methodAnnoataionInheritanceCheck();
+    state.setAnnotationRequireSet(annotationRequireSet);
   }
 
   public void doFlowDownCheck() {
@@ -49,8 +265,8 @@ public class SSJavaAnalysis {
     flowDownChecker.flowDownCheck();
   }
 
-  public void doLoopCheck() {
-    DefinitelyWrittenCheck checker = new DefinitelyWrittenCheck(state);
+  public void doDefinitelyWrittenCheck() {
+    DefinitelyWrittenCheck checker = new DefinitelyWrittenCheck(this, state);
     checker.definitelyWrittenCheck();
   }
 
@@ -64,38 +280,107 @@ public class SSJavaAnalysis {
         AnnotationDescriptor an = classAnnotations.elementAt(i);
         String marker = an.getMarker();
         if (marker.equals(LATTICE)) {
-          SSJavaLattice<String> locOrder = new SSJavaLattice<String>("_top_", "_bottom_");
+          SSJavaLattice<String> locOrder =
+              new SSJavaLattice<String>(SSJavaAnalysis.TOP, SSJavaAnalysis.BOTTOM);
           cd2lattice.put(cd, locOrder);
           parseClassLatticeDefinition(cd, an.getValue(), locOrder);
+
+          if (state.SSJAVADEBUG) {
+            // generate lattice dot file
+            writeLatticeDotFile(cd, null, locOrder);
+          }
+
         } else if (marker.equals(METHODDEFAULT)) {
-          MethodLattice<String> locOrder = new MethodLattice<String>("_top_", "_bottom_");
+          MethodLattice<String> locOrder =
+              new MethodLattice<String>(SSJavaAnalysis.TOP, SSJavaAnalysis.BOTTOM);
           cd2methodDefault.put(cd, locOrder);
-          parseMethodLatticeDefinition(cd, an.getValue(), locOrder);
+          parseMethodDefaultLatticeDefinition(cd, an.getValue(), locOrder);
         }
       }
-      if (!cd2lattice.containsKey(cd)) {
-        throw new Error("Class " + cd.getSymbol()
-            + " doesn't have any location hierarchy declaration at " + cd.getSourceFileName());
-      }
 
       for (Iterator method_it = cd.getMethods(); method_it.hasNext();) {
         MethodDescriptor md = (MethodDescriptor) method_it.next();
         // parsing location hierarchy declaration for the method
-        Vector<AnnotationDescriptor> methodAnnotations = cd.getModifier().getAnnotations();
-        for (int i = 0; i < methodAnnotations.size(); i++) {
-          AnnotationDescriptor an = methodAnnotations.elementAt(i);
-          if (an.getMarker().equals(LATTICE)) {
-            MethodLattice<String> locOrder = new MethodLattice<String>("_top_", "_bottom_");
-            cd2lattice.put(cd, locOrder);
-            parseMethodLatticeDefinition(cd, an.getValue(), locOrder);
+
+        if (needTobeAnnotated(md)) {
+          Vector<AnnotationDescriptor> methodAnnotations = md.getModifiers().getAnnotations();
+          if (methodAnnotations != null) {
+            for (int i = 0; i < methodAnnotations.size(); i++) {
+              AnnotationDescriptor an = methodAnnotations.elementAt(i);
+              if (an.getMarker().equals(LATTICE)) {
+                // developer explicitly defines method lattice
+                MethodLattice<String> locOrder =
+                    new MethodLattice<String>(SSJavaAnalysis.TOP, SSJavaAnalysis.BOTTOM);
+                md2lattice.put(md, locOrder);
+                parseMethodDefaultLatticeDefinition(cd, an.getValue(), locOrder);
+              } else if (an.getMarker().equals(TERMINATE)) {
+                // developer explicitly wants to skip loop termination analysis
+                String value = an.getValue();
+                int maxIteration = 0;
+                if (value != null) {
+                  maxIteration = Integer.parseInt(value);
+                }
+                skipLoopTerminate.put(md, new Integer(maxIteration));
+              }
+            }
+          }
+        }
+
+      }
+
+    }
+  }
+
+  public <T> void writeLatticeDotFile(ClassDescriptor cd, MethodDescriptor md,
+      SSJavaLattice<T> locOrder) {
+
+    String fileName = "lattice_";
+    if (md != null) {
+      fileName +=
+          cd.getSymbol().replaceAll("[\\W_]", "") + "_" + md.getSymbol().replaceAll("[\\W_]", "");
+    } else {
+      fileName += cd.getSymbol().replaceAll("[\\W_]", "");
+    }
+
+    Set<Pair<T, T>> pairSet = locOrder.getOrderingPairSet();
+
+    if (pairSet.size() > 0) {
+      try {
+        BufferedWriter bw = new BufferedWriter(new FileWriter(fileName + ".dot"));
+
+        bw.write("digraph " + fileName + " {\n");
+
+        for (Iterator iterator = pairSet.iterator(); iterator.hasNext();) {
+          // pair is in the form of <higher, lower>
+          Pair<T, T> pair = (Pair<T, T>) iterator.next();
+
+          T highLocId = pair.getFirst();
+          String highLocStr, lowLocStr;
+          if (locOrder.isSharedLoc(highLocId)) {
+            highLocStr = "\"" + highLocId + "*\"";
+          } else {
+            highLocStr = highLocId.toString();
           }
+          T lowLocId = pair.getSecond();
+          if (locOrder.isSharedLoc(lowLocId)) {
+            lowLocStr = "\"" + lowLocId + "*\"";
+          } else {
+            lowLocStr = lowLocId.toString();
+          }
+          bw.write(highLocId + " -> " + lowLocId + ";\n");
         }
+        bw.write("}\n");
+        bw.close();
+
+      } catch (IOException e) {
+        e.printStackTrace();
       }
 
     }
+
   }
 
-  private void parseMethodLatticeDefinition(ClassDescriptor cd, String value,
+  private void parseMethodDefaultLatticeDefinition(ClassDescriptor cd, String value,
       MethodLattice<String> locOrder) {
 
     value = value.replaceAll(" ", ""); // remove all blank spaces
@@ -119,9 +404,15 @@ public class SSJavaAnalysis {
       } else if (orderElement.startsWith(GLOBALLOC + "=")) {
         String globalLoc = orderElement.substring(10);
         locOrder.setGlobalLoc(globalLoc);
-      } else if (orderElement.contains("*")) {
+      } else if (orderElement.startsWith(RETURNLOC + "=")) {
+        String returnLoc = orderElement.substring(10);
+        locOrder.setReturnLoc(returnLoc);
+      } else if (orderElement.startsWith(PCLOC + "=")) {
+        String pcLoc = orderElement.substring(6);
+        locOrder.setPCLoc(pcLoc);
+      } else if (orderElement.endsWith("*")) {
         // spin loc definition
-        locOrder.addSpinLoc(orderElement);
+        locOrder.addSharedLoc(orderElement.substring(0, orderElement.length() - 1));
       } else {
         // single element
         locOrder.put(orderElement);
@@ -131,12 +422,12 @@ public class SSJavaAnalysis {
     // sanity checks
     if (locOrder.getThisLoc() != null && !locOrder.containsKey(locOrder.getThisLoc())) {
       throw new Error("Variable 'this' location '" + locOrder.getThisLoc()
-          + "' is not defined in the default local variable lattice at " + cd.getSourceFileName());
+          + "' is not defined in the local variable lattice at " + cd.getSourceFileName());
     }
 
     if (locOrder.getGlobalLoc() != null && !locOrder.containsKey(locOrder.getGlobalLoc())) {
       throw new Error("Variable global location '" + locOrder.getGlobalLoc()
-          + "' is not defined in the default local variable lattice at " + cd.getSourceFileName());
+          + "' is not defined in the local variable lattice at " + cd.getSourceFileName());
     }
   }
 
@@ -161,7 +452,7 @@ public class SSJavaAnalysis {
         }
       } else if (orderElement.contains("*")) {
         // spin loc definition
-        locOrder.addSpinLoc(orderElement);
+        locOrder.addSharedLoc(orderElement.substring(0, orderElement.length() - 1));
       } else {
         // single element
         locOrder.put(orderElement);
@@ -169,7 +460,7 @@ public class SSJavaAnalysis {
     }
 
     // sanity check
-    Set<String> spinLocSet = locOrder.getSpinLocSet();
+    Set<String> spinLocSet = locOrder.getSharedLocSet();
     for (Iterator iterator = spinLocSet.iterator(); iterator.hasNext();) {
       String spinLoc = (String) iterator.next();
       if (!locOrder.containsKey(spinLoc)) {
@@ -195,4 +486,215 @@ public class SSJavaAnalysis {
     return cd2lattice.get(cd);
   }
 
+  public MethodLattice<String> getMethodDefaultLattice(ClassDescriptor cd) {
+    return cd2methodDefault.get(cd);
+  }
+
+  public MethodLattice<String> getMethodLattice(MethodDescriptor md) {
+    if (md2lattice.containsKey(md)) {
+      return md2lattice.get(md);
+    } else {
+
+      if (cd2methodDefault.containsKey(md.getClassDesc())) {
+        return cd2methodDefault.get(md.getClassDesc());
+      } else {
+        throw new Error("Method Lattice of " + md + " is not defined.");
+      }
+
+    }
+  }
+
+  public boolean needToCheckLinearType(MethodDescriptor md) {
+    return linearTypeCheckMethodSet.contains(md);
+  }
+
+  public boolean needTobeAnnotated(MethodDescriptor md) {
+    return annotationRequireSet.contains(md);
+  }
+
+  public boolean needToBeAnnoated(ClassDescriptor cd) {
+    return annotationRequireClassSet.contains(cd);
+  }
+
+  public void addAnnotationRequire(ClassDescriptor cd) {
+    annotationRequireClassSet.add(cd);
+  }
+
+  public void addAnnotationRequire(MethodDescriptor md) {
+
+    ClassDescriptor cd = md.getClassDesc();
+    // if a method requires to be annotated, class containg that method also
+    // requires to be annotated
+    if (!isSSJavaUtil(cd)) {
+      annotationRequireClassSet.add(cd);
+      annotationRequireSet.add(md);
+    }
+  }
+
+  public Set<MethodDescriptor> getAnnotationRequireSet() {
+    return annotationRequireSet;
+  }
+
+  public void doLoopTerminationCheck(LoopOptimize lo, FlatMethod fm) {
+    LoopTerminate lt = new LoopTerminate(this, state);
+    if (needTobeAnnotated(fm.getMethod())) {
+      lt.terminateAnalysis(fm, lo.getLoopInvariant(fm));
+    }
+  }
+
+  public CallGraph getCallGraph() {
+    return callgraph;
+  }
+
+  public SSJavaLattice<String> getLattice(Descriptor d) {
+
+    if (d instanceof MethodDescriptor) {
+      return getMethodLattice((MethodDescriptor) d);
+    } else {
+      return getClassLattice((ClassDescriptor) d);
+    }
+
+  }
+
+  public boolean isSharedLocation(Location loc) {
+    SSJavaLattice<String> lattice = getLattice(loc.getDescriptor());
+    return lattice.getSharedLocSet().contains(loc.getLocIdentifier());
+  }
+
+  public void mapSharedLocation2Descriptor(Location loc, Descriptor d) {
+    Set<Descriptor> set = mapSharedLocation2DescriptorSet.get(loc);
+    if (set == null) {
+      set = new HashSet<Descriptor>();
+      mapSharedLocation2DescriptorSet.put(loc, set);
+    }
+    set.add(d);
+  }
+
+  public BuildFlat getBuildFlat() {
+    return bf;
+  }
+
+  public MethodDescriptor getMethodContainingSSJavaLoop() {
+    return methodContainingSSJavaLoop;
+  }
+
+  public void setMethodContainingSSJavaLoop(MethodDescriptor methodContainingSSJavaLoop) {
+    this.methodContainingSSJavaLoop = methodContainingSSJavaLoop;
+  }
+
+  public boolean isSSJavaUtil(ClassDescriptor cd) {
+    if (cd.getSymbol().equals("SSJAVA")) {
+      return true;
+    }
+    return false;
+  }
+
+  public void setFieldOnwership(MethodDescriptor md, FieldDescriptor field) {
+
+    Set<FieldDescriptor> fieldSet = mapMethodToOwnedFieldSet.get(md);
+    if (fieldSet == null) {
+      fieldSet = new HashSet<FieldDescriptor>();
+      mapMethodToOwnedFieldSet.put(md, fieldSet);
+    }
+    fieldSet.add(field);
+  }
+
+  public boolean isOwnedByMethod(MethodDescriptor md, FieldDescriptor field) {
+    Set<FieldDescriptor> fieldSet = mapMethodToOwnedFieldSet.get(md);
+    if (fieldSet != null) {
+      return fieldSet.contains(field);
+    }
+    return false;
+  }
+
+  public FlatNode getSSJavaLoopEntrance() {
+    return ssjavaLoopEntrance;
+  }
+
+  public void setSSJavaLoopEntrance(FlatNode ssjavaLoopEntrance) {
+    this.ssjavaLoopEntrance = ssjavaLoopEntrance;
+  }
+
+  public void addSameHeightWriteFlatNode(FlatNode fn) {
+    this.sameHeightWriteFlatNodeSet.add(fn);
+  }
+
+  public boolean isSameHeightWrite(FlatNode fn) {
+    return this.sameHeightWriteFlatNodeSet.contains(fn);
+  }
+
+  public 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 itr2 = callgraph.getCalleeSet(md).iterator();
+    while (itr2.hasNext()) {
+      MethodDescriptor dCallee = (MethodDescriptor) itr2.next();
+      addDependent(dCallee, 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);
+  }
+
+  public 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);
+  }
+
+  public Set<MethodDescriptor> getDependents(MethodDescriptor callee) {
+    Set<MethodDescriptor> deps = mapDescriptorToSetDependents.get(callee);
+    if (deps == null) {
+      deps = new HashSet<MethodDescriptor>();
+      mapDescriptorToSetDependents.put(callee, deps);
+    }
+    return deps;
+  }
+
 }