diff --git a/lib/Checker/GRExprEngine.cpp b/lib/Checker/GRExprEngine.cpp
new file mode 100644
index 0000000..978be8d
--- /dev/null
+++ b/lib/Checker/GRExprEngine.cpp
@@ -0,0 +1,3325 @@
+//=-- GRExprEngine.cpp - Path-Sensitive Expression-Level Dataflow ---*- C++ -*-=
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+//  This file defines a meta-engine for path-sensitive dataflow analysis that
+//  is built on GREngine, but provides the boilerplate to execute transfer
+//  functions and build the ExplodedGraph at the expression level.
+//
+//===----------------------------------------------------------------------===//
+#include "GRExprEngineInternalChecks.h"
+#include "clang/Checker/PathSensitive/GRExprEngine.h"
+#include "clang/Checker/PathSensitive/GRExprEngineBuilders.h"
+#include "clang/Checker/PathSensitive/Checker.h"
+#include "clang/AST/CharUnits.h"
+#include "clang/AST/ParentMap.h"
+#include "clang/AST/StmtObjC.h"
+#include "clang/Basic/Builtins.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/SourceManager.h"
+#include "clang/Basic/PrettyStackTrace.h"
+#include "llvm/Support/raw_ostream.h"
+#include "llvm/ADT/ImmutableList.h"
+#include "llvm/ADT/StringSwitch.h"
+
+#ifndef NDEBUG
+#include "llvm/Support/GraphWriter.h"
+#endif
+
+using namespace clang;
+using llvm::dyn_cast;
+using llvm::dyn_cast_or_null;
+using llvm::cast;
+using llvm::APSInt;
+
+//===----------------------------------------------------------------------===//
+// Utility functions.
+//===----------------------------------------------------------------------===//
+
+static inline Selector GetNullarySelector(const char* name, ASTContext& Ctx) {
+  IdentifierInfo* II = &Ctx.Idents.get(name);
+  return Ctx.Selectors.getSelector(0, &II);
+}
+
+
+static QualType GetCalleeReturnType(const CallExpr *CE) { 
+  const Expr *Callee = CE->getCallee();
+  QualType T = Callee->getType();
+  if (const PointerType *PT = T->getAs<PointerType>()) {
+    const FunctionType *FT = PT->getPointeeType()->getAs<FunctionType>();
+    T = FT->getResultType();
+  }
+  else {
+    const BlockPointerType *BT = T->getAs<BlockPointerType>();
+    T = BT->getPointeeType()->getAs<FunctionType>()->getResultType();
+  }
+  return T;
+}
+
+static bool CalleeReturnsReference(const CallExpr *CE) { 
+  return (bool) GetCalleeReturnType(CE)->getAs<ReferenceType>();
+}
+
+static bool ReceiverReturnsReference(const ObjCMessageExpr *ME) {
+  const ObjCMethodDecl *MD = ME->getMethodDecl();
+  if (!MD)
+    return false;
+  return MD->getResultType()->getAs<ReferenceType>();
+}
+
+#ifndef NDEBUG
+static bool ReceiverReturnsReferenceOrRecord(const ObjCMessageExpr *ME) {
+  const ObjCMethodDecl *MD = ME->getMethodDecl();
+  if (!MD)
+    return false;
+  QualType T = MD->getResultType();
+  return T->getAs<RecordType>() || T->getAs<ReferenceType>();
+}
+
+static bool CalleeReturnsReferenceOrRecord(const CallExpr *CE) {
+  QualType T = GetCalleeReturnType(CE);
+  return T->getAs<ReferenceType>() || T->getAs<RecordType>();
+}
+#endif
+
+//===----------------------------------------------------------------------===//
+// Batch auditor.  DEPRECATED.
+//===----------------------------------------------------------------------===//
+
+namespace {
+
+class MappedBatchAuditor : public GRSimpleAPICheck {
+  typedef llvm::ImmutableList<GRSimpleAPICheck*> Checks;
+  typedef llvm::DenseMap<void*,Checks> MapTy;
+
+  MapTy M;
+  Checks::Factory F;
+  Checks AllStmts;
+
+public:
+  MappedBatchAuditor(llvm::BumpPtrAllocator& Alloc) :
+    F(Alloc), AllStmts(F.GetEmptyList()) {}
+
+  virtual ~MappedBatchAuditor() {
+    llvm::DenseSet<GRSimpleAPICheck*> AlreadyVisited;
+
+    for (MapTy::iterator MI = M.begin(), ME = M.end(); MI != ME; ++MI)
+      for (Checks::iterator I=MI->second.begin(), E=MI->second.end(); I!=E;++I){
+
+        GRSimpleAPICheck* check = *I;
+
+        if (AlreadyVisited.count(check))
+          continue;
+
+        AlreadyVisited.insert(check);
+        delete check;
+      }
+  }
+
+  void AddCheck(GRSimpleAPICheck *A, Stmt::StmtClass C) {
+    assert (A && "Check cannot be null.");
+    void* key = reinterpret_cast<void*>((uintptr_t) C);
+    MapTy::iterator I = M.find(key);
+    M[key] = F.Concat(A, I == M.end() ? F.GetEmptyList() : I->second);
+  }
+
+  void AddCheck(GRSimpleAPICheck *A) {
+    assert (A && "Check cannot be null.");
+    AllStmts = F.Concat(A, AllStmts);
+  }
+
+  virtual bool Audit(ExplodedNode* N, GRStateManager& VMgr) {
+    // First handle the auditors that accept all statements.
+    bool isSink = false;
+    for (Checks::iterator I = AllStmts.begin(), E = AllStmts.end(); I!=E; ++I)
+      isSink |= (*I)->Audit(N, VMgr);
+
+    // Next handle the auditors that accept only specific statements.
+    const Stmt* S = cast<PostStmt>(N->getLocation()).getStmt();
+    void* key = reinterpret_cast<void*>((uintptr_t) S->getStmtClass());
+    MapTy::iterator MI = M.find(key);
+    if (MI != M.end()) {
+      for (Checks::iterator I=MI->second.begin(), E=MI->second.end(); I!=E; ++I)
+        isSink |= (*I)->Audit(N, VMgr);
+    }
+
+    return isSink;
+  }
+};
+
+} // end anonymous namespace
+
+//===----------------------------------------------------------------------===//
+// Checker worklist routines.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::CheckerVisit(Stmt *S, ExplodedNodeSet &Dst,
+                                ExplodedNodeSet &Src, bool isPrevisit) {
+
+  if (Checkers.empty()) {
+    Dst.insert(Src);
+    return;
+  }
+
+  ExplodedNodeSet Tmp;
+  ExplodedNodeSet *PrevSet = &Src;
+
+  for (CheckersOrdered::iterator I=Checkers.begin(),E=Checkers.end(); I!=E;++I){
+    ExplodedNodeSet *CurrSet = 0;
+    if (I+1 == E)
+      CurrSet = &Dst;
+    else {
+      CurrSet = (PrevSet == &Tmp) ? &Src : &Tmp;
+      CurrSet->clear();
+    }    
+    void *tag = I->first;
+    Checker *checker = I->second;
+    
+    for (ExplodedNodeSet::iterator NI = PrevSet->begin(), NE = PrevSet->end();
+         NI != NE; ++NI)
+      checker->GR_Visit(*CurrSet, *Builder, *this, S, *NI, tag, isPrevisit);
+    PrevSet = CurrSet;
+  }
+
+  // Don't autotransition.  The CheckerContext objects should do this
+  // automatically.
+}
+
+void GRExprEngine::CheckerEvalNilReceiver(const ObjCMessageExpr *ME, 
+                                          ExplodedNodeSet &Dst,
+                                          const GRState *state,
+                                          ExplodedNode *Pred) {
+  bool Evaluated = false;
+  ExplodedNodeSet DstTmp;
+
+  for (CheckersOrdered::iterator I=Checkers.begin(),E=Checkers.end();I!=E;++I) {
+    void *tag = I->first;
+    Checker *checker = I->second;
+
+    if (checker->GR_EvalNilReceiver(DstTmp, *Builder, *this, ME, Pred, state,
+                                    tag)) {
+      Evaluated = true;
+      break;
+    } else
+      // The checker didn't evaluate the expr. Restore the Dst.
+      DstTmp.clear();
+  }
+
+  if (Evaluated)
+    Dst.insert(DstTmp);
+  else
+    Dst.insert(Pred);
+}
+
+// CheckerEvalCall returns true if one of the checkers processed the node.
+// This may return void when all call evaluation logic goes to some checker
+// in the future.
+bool GRExprEngine::CheckerEvalCall(const CallExpr *CE, 
+                                   ExplodedNodeSet &Dst, 
+                                   ExplodedNode *Pred) {
+  bool Evaluated = false;
+  ExplodedNodeSet DstTmp;
+
+  for (CheckersOrdered::iterator I=Checkers.begin(),E=Checkers.end();I!=E;++I) {
+    void *tag = I->first;
+    Checker *checker = I->second;
+
+    if (checker->GR_EvalCallExpr(DstTmp, *Builder, *this, CE, Pred, tag)) {
+      Evaluated = true;
+      break;
+    } else
+      // The checker didn't evaluate the expr. Restore the DstTmp set.
+      DstTmp.clear();
+  }
+
+  if (Evaluated)
+    Dst.insert(DstTmp);
+  else
+    Dst.insert(Pred);
+
+  return Evaluated;
+}
+
+// FIXME: This is largely copy-paste from CheckerVisit().  Need to 
+// unify.
+void GRExprEngine::CheckerVisitBind(const Stmt *AssignE, const Stmt *StoreE,
+                                    ExplodedNodeSet &Dst,
+                                    ExplodedNodeSet &Src,
+                                    SVal location, SVal val, bool isPrevisit) {
+  
+  if (Checkers.empty()) {
+    Dst.insert(Src);
+    return;
+  }
+  
+  ExplodedNodeSet Tmp;
+  ExplodedNodeSet *PrevSet = &Src;
+  
+  for (CheckersOrdered::iterator I=Checkers.begin(),E=Checkers.end(); I!=E; ++I)
+  {
+    ExplodedNodeSet *CurrSet = 0;
+    if (I+1 == E)
+      CurrSet = &Dst;
+    else {
+      CurrSet = (PrevSet == &Tmp) ? &Src : &Tmp;
+      CurrSet->clear();
+    }
+
+    void *tag = I->first;
+    Checker *checker = I->second;
+    
+    for (ExplodedNodeSet::iterator NI = PrevSet->begin(), NE = PrevSet->end();
+         NI != NE; ++NI)
+      checker->GR_VisitBind(*CurrSet, *Builder, *this, AssignE, StoreE,
+                            *NI, tag, location, val, isPrevisit);
+    
+    // Update which NodeSet is the current one.
+    PrevSet = CurrSet;
+  }
+  
+  // Don't autotransition.  The CheckerContext objects should do this
+  // automatically.
+}
+//===----------------------------------------------------------------------===//
+// Engine construction and deletion.
+//===----------------------------------------------------------------------===//
+
+static void RegisterInternalChecks(GRExprEngine &Eng) {
+  // Register internal "built-in" BugTypes with the BugReporter. These BugTypes
+  // are different than what probably many checks will do since they don't
+  // create BugReports on-the-fly but instead wait until GRExprEngine finishes
+  // analyzing a function.  Generation of BugReport objects is done via a call
+  // to 'FlushReports' from BugReporter.
+  // The following checks do not need to have their associated BugTypes
+  // explicitly registered with the BugReporter.  If they issue any BugReports,
+  // their associated BugType will get registered with the BugReporter
+  // automatically.  Note that the check itself is owned by the GRExprEngine
+  // object.  
+  RegisterAdjustedReturnValueChecker(Eng);
+  RegisterAttrNonNullChecker(Eng);
+  RegisterCallAndMessageChecker(Eng);
+  RegisterDereferenceChecker(Eng);
+  RegisterVLASizeChecker(Eng);
+  RegisterDivZeroChecker(Eng);
+  RegisterReturnStackAddressChecker(Eng);
+  RegisterReturnUndefChecker(Eng);
+  RegisterUndefinedArraySubscriptChecker(Eng);
+  RegisterUndefinedAssignmentChecker(Eng);
+  RegisterUndefBranchChecker(Eng);
+  RegisterUndefResultChecker(Eng);
+
+  // This is not a checker yet.
+  RegisterNoReturnFunctionChecker(Eng);
+  RegisterBuiltinFunctionChecker(Eng);
+  RegisterOSAtomicChecker(Eng);
+}
+
+GRExprEngine::GRExprEngine(AnalysisManager &mgr, GRTransferFuncs *tf)
+  : AMgr(mgr),
+    CoreEngine(mgr.getASTContext(), *this),
+    G(CoreEngine.getGraph()),
+    Builder(NULL),
+    StateMgr(G.getContext(), mgr.getStoreManagerCreator(),
+             mgr.getConstraintManagerCreator(), G.getAllocator(),
+             *this),
+    SymMgr(StateMgr.getSymbolManager()),
+    ValMgr(StateMgr.getValueManager()),
+    SVator(ValMgr.getSValuator()),
+    CurrentStmt(NULL),
+    NSExceptionII(NULL), NSExceptionInstanceRaiseSelectors(NULL),
+    RaiseSel(GetNullarySelector("raise", G.getContext())),
+    BR(mgr, *this), TF(tf) {
+  // Register internal checks.
+  RegisterInternalChecks(*this);
+  
+  // FIXME: Eventually remove the TF object entirely.
+  TF->RegisterChecks(*this);
+  TF->RegisterPrinters(getStateManager().Printers);
+}
+
+GRExprEngine::~GRExprEngine() {
+  BR.FlushReports();
+  delete [] NSExceptionInstanceRaiseSelectors;
+  for (CheckersOrdered::iterator I=Checkers.begin(), E=Checkers.end(); I!=E;++I)
+    delete I->second;
+}
+
+//===----------------------------------------------------------------------===//
+// Utility methods.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::AddCheck(GRSimpleAPICheck* A, Stmt::StmtClass C) {
+  if (!BatchAuditor)
+    BatchAuditor.reset(new MappedBatchAuditor(getGraph().getAllocator()));
+
+  ((MappedBatchAuditor*) BatchAuditor.get())->AddCheck(A, C);
+}
+
+void GRExprEngine::AddCheck(GRSimpleAPICheck *A) {
+  if (!BatchAuditor)
+    BatchAuditor.reset(new MappedBatchAuditor(getGraph().getAllocator()));
+
+  ((MappedBatchAuditor*) BatchAuditor.get())->AddCheck(A);
+}
+
+const GRState* GRExprEngine::getInitialState(const LocationContext *InitLoc) {
+  const GRState *state = StateMgr.getInitialState(InitLoc);
+
+  // Preconditions.
+
+  // FIXME: It would be nice if we had a more general mechanism to add
+  // such preconditions.  Some day.
+  do {
+    const Decl *D = InitLoc->getDecl();  
+    if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
+      // Precondition: the first argument of 'main' is an integer guaranteed
+      //  to be > 0.
+      const IdentifierInfo *II = FD->getIdentifier();
+      if (!II || !(II->getName() == "main" && FD->getNumParams() > 0))
+        break;
+
+      const ParmVarDecl *PD = FD->getParamDecl(0);
+      QualType T = PD->getType();
+      if (!T->isIntegerType())
+        break;
+    
+      const MemRegion *R = state->getRegion(PD, InitLoc);
+      if (!R)
+        break;
+    
+      SVal V = state->getSVal(loc::MemRegionVal(R));
+      SVal Constraint_untested = EvalBinOp(state, BinaryOperator::GT, V,
+                                           ValMgr.makeZeroVal(T),
+                                           getContext().IntTy);
+
+      DefinedOrUnknownSVal *Constraint =
+        dyn_cast<DefinedOrUnknownSVal>(&Constraint_untested);
+      
+      if (!Constraint)
+        break;
+      
+      if (const GRState *newState = state->Assume(*Constraint, true))
+        state = newState;
+      
+      break;
+    }
+
+    if (const ObjCMethodDecl *MD = dyn_cast<ObjCMethodDecl>(D)) {    
+      // Precondition: 'self' is always non-null upon entry to an Objective-C
+      // method.
+      const ImplicitParamDecl *SelfD = MD->getSelfDecl();
+      const MemRegion *R = state->getRegion(SelfD, InitLoc);
+      SVal V = state->getSVal(loc::MemRegionVal(R));
+    
+      if (const Loc *LV = dyn_cast<Loc>(&V)) {
+        // Assume that the pointer value in 'self' is non-null.
+        state = state->Assume(*LV, true);
+        assert(state && "'self' cannot be null");
+      }
+    }
+  } while (0);
+  
+  return state;
+}
+
+//===----------------------------------------------------------------------===//
+// Top-level transfer function logic (Dispatcher).
+//===----------------------------------------------------------------------===//
+
+/// EvalAssume - Called by ConstraintManager. Used to call checker-specific
+///  logic for handling assumptions on symbolic values.
+const GRState *GRExprEngine::ProcessAssume(const GRState *state, SVal cond,
+                                           bool assumption) {  
+  for (CheckersOrdered::iterator I = Checkers.begin(), E = Checkers.end();
+        I != E; ++I) {
+
+    if (!state)
+      return NULL;  
+    
+    state = I->second->EvalAssume(state, cond, assumption);
+  }
+  
+  if (!state)
+    return NULL;
+  
+  return TF->EvalAssume(state, cond, assumption);
+}
+
+void GRExprEngine::ProcessStmt(CFGElement CE, GRStmtNodeBuilder& builder) {
+  CurrentStmt = CE.getStmt();
+  PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
+                                CurrentStmt->getLocStart(),
+                                "Error evaluating statement");
+
+  Builder = &builder;
+  EntryNode = builder.getLastNode();
+
+  // Set up our simple checks.
+  if (BatchAuditor)
+    Builder->setAuditor(BatchAuditor.get());
+
+  // Create the cleaned state.
+  const ExplodedNode *BasePred = Builder->getBasePredecessor();
+  SymbolReaper SymReaper(BasePred->getLiveVariables(), SymMgr,
+                        BasePred->getLocationContext()->getCurrentStackFrame());
+  CleanedState = AMgr.shouldPurgeDead()
+    ? StateMgr.RemoveDeadBindings(EntryNode->getState(), CurrentStmt, SymReaper)
+    : EntryNode->getState();
+
+  // Process any special transfer function for dead symbols.
+  ExplodedNodeSet Tmp;
+
+  if (!SymReaper.hasDeadSymbols())
+    Tmp.Add(EntryNode);
+  else {
+    SaveAndRestore<bool> OldSink(Builder->BuildSinks);
+    SaveOr OldHasGen(Builder->HasGeneratedNode);
+
+    SaveAndRestore<bool> OldPurgeDeadSymbols(Builder->PurgingDeadSymbols);
+    Builder->PurgingDeadSymbols = true;
+
+    // FIXME: This should soon be removed.
+    ExplodedNodeSet Tmp2;
+    getTF().EvalDeadSymbols(Tmp2, *this, *Builder, EntryNode, CurrentStmt,
+                            CleanedState, SymReaper);
+
+    if (Checkers.empty())
+      Tmp.insert(Tmp2);
+    else {
+      ExplodedNodeSet Tmp3;
+      ExplodedNodeSet *SrcSet = &Tmp2;
+      for (CheckersOrdered::iterator I = Checkers.begin(), E = Checkers.end();
+           I != E; ++I) {
+        ExplodedNodeSet *DstSet = 0;
+        if (I+1 == E)
+          DstSet = &Tmp;
+        else {
+          DstSet = (SrcSet == &Tmp2) ? &Tmp3 : &Tmp2;
+          DstSet->clear();
+        }
+
+        void *tag = I->first;
+        Checker *checker = I->second;
+        for (ExplodedNodeSet::iterator NI = SrcSet->begin(), NE = SrcSet->end();
+             NI != NE; ++NI)
+          checker->GR_EvalDeadSymbols(*DstSet, *Builder, *this, CurrentStmt,
+                                      *NI, SymReaper, tag);
+        SrcSet = DstSet;
+      }
+    }
+
+    if (!Builder->BuildSinks && !Builder->HasGeneratedNode)
+      Tmp.Add(EntryNode);
+  }
+
+  bool HasAutoGenerated = false;
+
+  for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+
+    ExplodedNodeSet Dst;
+
+    // Set the cleaned state.
+    Builder->SetCleanedState(*I == EntryNode ? CleanedState : GetState(*I));
+
+    // Visit the statement.
+    if (CE.asLValue())
+      VisitLValue(cast<Expr>(CurrentStmt), *I, Dst);
+    else
+      Visit(CurrentStmt, *I, Dst);
+
+    // Do we need to auto-generate a node?  We only need to do this to generate
+    // a node with a "cleaned" state; GRCoreEngine will actually handle
+    // auto-transitions for other cases.
+    if (Dst.size() == 1 && *Dst.begin() == EntryNode
+        && !Builder->HasGeneratedNode && !HasAutoGenerated) {
+      HasAutoGenerated = true;
+      builder.generateNode(CurrentStmt, GetState(EntryNode), *I);
+    }
+  }
+
+  // NULL out these variables to cleanup.
+  CleanedState = NULL;
+  EntryNode = NULL;
+
+  CurrentStmt = 0;
+
+  Builder = NULL;
+}
+
+void GRExprEngine::Visit(Stmt* S, ExplodedNode* Pred, ExplodedNodeSet& Dst) {
+  PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
+                                S->getLocStart(),
+                                "Error evaluating statement");
+
+  // FIXME: add metadata to the CFG so that we can disable
+  //  this check when we KNOW that there is no block-level subexpression.
+  //  The motivation is that this check requires a hashtable lookup.
+
+  if (S != CurrentStmt && Pred->getLocationContext()->getCFG()->isBlkExpr(S)) {
+    Dst.Add(Pred);
+    return;
+  }
+
+  switch (S->getStmtClass()) {
+    // C++ stuff we don't support yet.
+    case Stmt::CXXMemberCallExprClass:
+    case Stmt::CXXNamedCastExprClass:
+    case Stmt::CXXStaticCastExprClass:
+    case Stmt::CXXDynamicCastExprClass:
+    case Stmt::CXXReinterpretCastExprClass:
+    case Stmt::CXXConstCastExprClass:
+    case Stmt::CXXFunctionalCastExprClass:
+    case Stmt::CXXTypeidExprClass:
+    case Stmt::CXXBoolLiteralExprClass:
+    case Stmt::CXXNullPtrLiteralExprClass:
+    case Stmt::CXXThrowExprClass:
+    case Stmt::CXXDefaultArgExprClass:
+    case Stmt::CXXZeroInitValueExprClass:
+    case Stmt::CXXNewExprClass:
+    case Stmt::CXXDeleteExprClass:
+    case Stmt::CXXPseudoDestructorExprClass:
+    case Stmt::UnresolvedLookupExprClass:
+    case Stmt::UnaryTypeTraitExprClass:
+    case Stmt::DependentScopeDeclRefExprClass:
+    case Stmt::CXXConstructExprClass:
+    case Stmt::CXXBindTemporaryExprClass:
+    case Stmt::CXXExprWithTemporariesClass:
+    case Stmt::CXXTemporaryObjectExprClass:
+    case Stmt::CXXUnresolvedConstructExprClass:
+    case Stmt::CXXDependentScopeMemberExprClass:
+    case Stmt::UnresolvedMemberExprClass:
+    case Stmt::CXXCatchStmtClass:
+    case Stmt::CXXTryStmtClass: {
+      SaveAndRestore<bool> OldSink(Builder->BuildSinks);
+      Builder->BuildSinks = true;
+      MakeNode(Dst, S, Pred, GetState(Pred));
+      break;
+    }
+
+    default:
+      // Cases we intentionally have "default" handle:
+      //   AddrLabelExpr, IntegerLiteral, CharacterLiteral
+
+      Dst.Add(Pred); // No-op. Simply propagate the current state unchanged.
+      break;
+
+    case Stmt::ArraySubscriptExprClass:
+      VisitArraySubscriptExpr(cast<ArraySubscriptExpr>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::AsmStmtClass:
+      VisitAsmStmt(cast<AsmStmt>(S), Pred, Dst);
+      break;
+      
+    case Stmt::BlockDeclRefExprClass:
+      VisitBlockDeclRefExpr(cast<BlockDeclRefExpr>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::BlockExprClass:
+      VisitBlockExpr(cast<BlockExpr>(S), Pred, Dst);
+      break;
+
+    case Stmt::BinaryOperatorClass: {
+      BinaryOperator* B = cast<BinaryOperator>(S);
+
+      if (B->isLogicalOp()) {
+        VisitLogicalExpr(B, Pred, Dst);
+        break;
+      }
+      else if (B->getOpcode() == BinaryOperator::Comma) {
+        const GRState* state = GetState(Pred);
+        MakeNode(Dst, B, Pred, state->BindExpr(B, state->getSVal(B->getRHS())));
+        break;
+      }
+
+      if (AMgr.shouldEagerlyAssume() && 
+          (B->isRelationalOp() || B->isEqualityOp())) {
+        ExplodedNodeSet Tmp;
+        VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Tmp, false);
+        EvalEagerlyAssume(Dst, Tmp, cast<Expr>(S));
+      }
+      else
+        VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst, false);
+
+      break;
+    }
+
+    case Stmt::CallExprClass:
+    case Stmt::CXXOperatorCallExprClass: {
+      CallExpr* C = cast<CallExpr>(S);
+      VisitCall(C, Pred, C->arg_begin(), C->arg_end(), Dst, false);
+      break;
+    }
+
+      // FIXME: ChooseExpr is really a constant.  We need to fix
+      //        the CFG do not model them as explicit control-flow.
+
+    case Stmt::ChooseExprClass: { // __builtin_choose_expr
+      ChooseExpr* C = cast<ChooseExpr>(S);
+      VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst);
+      break;
+    }
+
+    case Stmt::CompoundAssignOperatorClass:
+      VisitBinaryOperator(cast<BinaryOperator>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::CompoundLiteralExprClass:
+      VisitCompoundLiteralExpr(cast<CompoundLiteralExpr>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::ConditionalOperatorClass: { // '?' operator
+      ConditionalOperator* C = cast<ConditionalOperator>(S);
+      VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst);
+      break;
+    }
+
+    case Stmt::CXXThisExprClass:
+      VisitCXXThisExpr(cast<CXXThisExpr>(S), Pred, Dst);
+      break;
+
+    case Stmt::DeclRefExprClass:
+      VisitDeclRefExpr(cast<DeclRefExpr>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::DeclStmtClass:
+      VisitDeclStmt(cast<DeclStmt>(S), Pred, Dst);
+      break;
+
+    case Stmt::ForStmtClass:
+      // This case isn't for branch processing, but for handling the
+      // initialization of a condition variable.
+      VisitCondInit(cast<ForStmt>(S)->getConditionVariable(), S, Pred, Dst);
+      break;      
+
+    case Stmt::ImplicitCastExprClass:
+    case Stmt::CStyleCastExprClass: {
+      CastExpr* C = cast<CastExpr>(S);
+      VisitCast(C, C->getSubExpr(), Pred, Dst, false);
+      break;
+    }
+      
+    case Stmt::IfStmtClass:
+      // This case isn't for branch processing, but for handling the
+      // initialization of a condition variable.
+      VisitCondInit(cast<IfStmt>(S)->getConditionVariable(), S, Pred, Dst);
+      break;
+
+    case Stmt::InitListExprClass:
+      VisitInitListExpr(cast<InitListExpr>(S), Pred, Dst);
+      break;
+
+    case Stmt::MemberExprClass:
+      VisitMemberExpr(cast<MemberExpr>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::ObjCIvarRefExprClass:
+      VisitObjCIvarRefExpr(cast<ObjCIvarRefExpr>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::ObjCForCollectionStmtClass:
+      VisitObjCForCollectionStmt(cast<ObjCForCollectionStmt>(S), Pred, Dst);
+      break;
+
+    case Stmt::ObjCMessageExprClass:
+      VisitObjCMessageExpr(cast<ObjCMessageExpr>(S), Pred, Dst, false);
+      break;
+
+    case Stmt::ObjCAtThrowStmtClass: {
+      // FIXME: This is not complete.  We basically treat @throw as
+      // an abort.
+      SaveAndRestore<bool> OldSink(Builder->BuildSinks);
+      Builder->BuildSinks = true;
+      MakeNode(Dst, S, Pred, GetState(Pred));
+      break;
+    }
+
+    case Stmt::ParenExprClass:
+      Visit(cast<ParenExpr>(S)->getSubExpr()->IgnoreParens(), Pred, Dst);
+      break;
+
+    case Stmt::ReturnStmtClass:
+      VisitReturnStmt(cast<ReturnStmt>(S), Pred, Dst);
+      break;
+
+    case Stmt::SizeOfAlignOfExprClass:
+      VisitSizeOfAlignOfExpr(cast<SizeOfAlignOfExpr>(S), Pred, Dst);
+      break;
+
+    case Stmt::StmtExprClass: {
+      StmtExpr* SE = cast<StmtExpr>(S);
+
+      if (SE->getSubStmt()->body_empty()) {
+        // Empty statement expression.
+        assert(SE->getType() == getContext().VoidTy
+               && "Empty statement expression must have void type.");
+        Dst.Add(Pred);
+        break;
+      }
+
+      if (Expr* LastExpr = dyn_cast<Expr>(*SE->getSubStmt()->body_rbegin())) {
+        const GRState* state = GetState(Pred);
+        MakeNode(Dst, SE, Pred, state->BindExpr(SE, state->getSVal(LastExpr)));
+      }
+      else
+        Dst.Add(Pred);
+
+      break;
+    }
+
+    case Stmt::StringLiteralClass:
+      VisitLValue(cast<StringLiteral>(S), Pred, Dst);
+      break;
+      
+    case Stmt::SwitchStmtClass:
+      // This case isn't for branch processing, but for handling the
+      // initialization of a condition variable.
+      VisitCondInit(cast<SwitchStmt>(S)->getConditionVariable(), S, Pred, Dst);
+      break;
+
+    case Stmt::UnaryOperatorClass: {
+      UnaryOperator *U = cast<UnaryOperator>(S);
+      if (AMgr.shouldEagerlyAssume()&&(U->getOpcode() == UnaryOperator::LNot)) {
+        ExplodedNodeSet Tmp;
+        VisitUnaryOperator(U, Pred, Tmp, false);
+        EvalEagerlyAssume(Dst, Tmp, U);
+      }
+      else
+        VisitUnaryOperator(U, Pred, Dst, false);
+      break;
+    }
+      
+    case Stmt::WhileStmtClass:
+      // This case isn't for branch processing, but for handling the
+      // initialization of a condition variable.
+      VisitCondInit(cast<WhileStmt>(S)->getConditionVariable(), S, Pred, Dst);
+      break;      
+  }
+}
+
+void GRExprEngine::VisitLValue(Expr* Ex, ExplodedNode* Pred,
+                               ExplodedNodeSet& Dst) {
+  
+  PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
+                                Ex->getLocStart(),
+                                "Error evaluating statement");
+
+
+  Ex = Ex->IgnoreParens();
+
+  if (Ex != CurrentStmt && Pred->getLocationContext()->getCFG()->isBlkExpr(Ex)){
+    Dst.Add(Pred);
+    return;
+  }
+
+  switch (Ex->getStmtClass()) {
+    // C++ stuff we don't support yet.
+    case Stmt::CXXExprWithTemporariesClass:
+    case Stmt::CXXMemberCallExprClass:
+    case Stmt::CXXZeroInitValueExprClass: {
+      SaveAndRestore<bool> OldSink(Builder->BuildSinks);
+      Builder->BuildSinks = true;
+      MakeNode(Dst, Ex, Pred, GetState(Pred));
+      break;
+    }
+
+    case Stmt::ArraySubscriptExprClass:
+      VisitArraySubscriptExpr(cast<ArraySubscriptExpr>(Ex), Pred, Dst, true);
+      return;
+
+    case Stmt::BinaryOperatorClass:
+    case Stmt::CompoundAssignOperatorClass:
+      VisitBinaryOperator(cast<BinaryOperator>(Ex), Pred, Dst, true);
+      return;
+      
+    case Stmt::BlockDeclRefExprClass:
+      VisitBlockDeclRefExpr(cast<BlockDeclRefExpr>(Ex), Pred, Dst, true);
+      return;
+      
+    case Stmt::CallExprClass:
+    case Stmt::CXXOperatorCallExprClass: {
+      CallExpr *C = cast<CallExpr>(Ex);
+      assert(CalleeReturnsReferenceOrRecord(C));
+      VisitCall(C, Pred, C->arg_begin(), C->arg_end(), Dst, true);      
+      break;
+    }
+      
+    case Stmt::CompoundLiteralExprClass:
+      VisitCompoundLiteralExpr(cast<CompoundLiteralExpr>(Ex), Pred, Dst, true);
+      return;      
+
+    case Stmt::DeclRefExprClass:
+      VisitDeclRefExpr(cast<DeclRefExpr>(Ex), Pred, Dst, true);
+      return;
+      
+    case Stmt::ImplicitCastExprClass:
+    case Stmt::CStyleCastExprClass: {
+      CastExpr *C = cast<CastExpr>(Ex);
+      QualType T = Ex->getType();
+      VisitCast(C, C->getSubExpr(), Pred, Dst, true);
+      break;
+    }
+      
+    case Stmt::MemberExprClass:
+      VisitMemberExpr(cast<MemberExpr>(Ex), Pred, Dst, true);
+      return;
+
+    case Stmt::ObjCIvarRefExprClass:
+      VisitObjCIvarRefExpr(cast<ObjCIvarRefExpr>(Ex), Pred, Dst, true);
+      return;
+      
+    case Stmt::ObjCMessageExprClass: {
+      ObjCMessageExpr *ME = cast<ObjCMessageExpr>(Ex);
+      assert(ReceiverReturnsReferenceOrRecord(ME));
+      VisitObjCMessageExpr(ME, Pred, Dst, true); 
+      return;
+    }
+
+    case Stmt::ObjCPropertyRefExprClass:
+    case Stmt::ObjCImplicitSetterGetterRefExprClass:
+      // FIXME: Property assignments are lvalues, but not really "locations".
+      //  e.g.:  self.x = something;
+      //  Here the "self.x" really can translate to a method call (setter) when
+      //  the assignment is made.  Moreover, the entire assignment expression
+      //  evaluate to whatever "something" is, not calling the "getter" for
+      //  the property (which would make sense since it can have side effects).
+      //  We'll probably treat this as a location, but not one that we can
+      //  take the address of.  Perhaps we need a new SVal class for cases
+      //  like thsis?
+      //  Note that we have a similar problem for bitfields, since they don't
+      //  have "locations" in the sense that we can take their address.
+      Dst.Add(Pred);
+      return;
+
+    case Stmt::StringLiteralClass: {
+      const GRState* state = GetState(Pred);
+      SVal V = state->getLValue(cast<StringLiteral>(Ex));
+      MakeNode(Dst, Ex, Pred, state->BindExpr(Ex, V));
+      return;
+    }
+
+    case Stmt::UnaryOperatorClass:
+      VisitUnaryOperator(cast<UnaryOperator>(Ex), Pred, Dst, true);
+      return;
+
+    // In C++, binding an rvalue to a reference requires to create an object.
+    case Stmt::IntegerLiteralClass:
+      CreateCXXTemporaryObject(Ex, Pred, Dst);
+      return;
+      
+    default:
+      // Arbitrary subexpressions can return aggregate temporaries that
+      // can be used in a lvalue context.  We need to enhance our support
+      // of such temporaries in both the environment and the store, so right
+      // now we just do a regular visit.
+      assert ((Ex->getType()->isAggregateType()) &&
+              "Other kinds of expressions with non-aggregate/union types do"
+              " not have lvalues.");
+
+      Visit(Ex, Pred, Dst);
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Block entrance.  (Update counters).
+//===----------------------------------------------------------------------===//
+
+bool GRExprEngine::ProcessBlockEntrance(CFGBlock* B, const GRState*,
+                                        GRBlockCounter BC) {
+
+  return BC.getNumVisited(B->getBlockID()) < 3;
+}
+
+//===----------------------------------------------------------------------===//
+// Generic node creation.
+//===----------------------------------------------------------------------===//
+
+ExplodedNode* GRExprEngine::MakeNode(ExplodedNodeSet& Dst, Stmt* S,
+                                     ExplodedNode* Pred, const GRState* St,
+                                     ProgramPoint::Kind K, const void *tag) {
+  assert (Builder && "GRStmtNodeBuilder not present.");
+  SaveAndRestore<const void*> OldTag(Builder->Tag);
+  Builder->Tag = tag;
+  return Builder->MakeNode(Dst, S, Pred, St, K);
+}
+
+//===----------------------------------------------------------------------===//
+// Branch processing.
+//===----------------------------------------------------------------------===//
+
+const GRState* GRExprEngine::MarkBranch(const GRState* state,
+                                           Stmt* Terminator,
+                                           bool branchTaken) {
+
+  switch (Terminator->getStmtClass()) {
+    default:
+      return state;
+
+    case Stmt::BinaryOperatorClass: { // '&&' and '||'
+
+      BinaryOperator* B = cast<BinaryOperator>(Terminator);
+      BinaryOperator::Opcode Op = B->getOpcode();
+
+      assert (Op == BinaryOperator::LAnd || Op == BinaryOperator::LOr);
+
+      // For &&, if we take the true branch, then the value of the whole
+      // expression is that of the RHS expression.
+      //
+      // For ||, if we take the false branch, then the value of the whole
+      // expression is that of the RHS expression.
+
+      Expr* Ex = (Op == BinaryOperator::LAnd && branchTaken) ||
+                 (Op == BinaryOperator::LOr && !branchTaken)
+               ? B->getRHS() : B->getLHS();
+
+      return state->BindExpr(B, UndefinedVal(Ex));
+    }
+
+    case Stmt::ConditionalOperatorClass: { // ?:
+
+      ConditionalOperator* C = cast<ConditionalOperator>(Terminator);
+
+      // For ?, if branchTaken == true then the value is either the LHS or
+      // the condition itself. (GNU extension).
+
+      Expr* Ex;
+
+      if (branchTaken)
+        Ex = C->getLHS() ? C->getLHS() : C->getCond();
+      else
+        Ex = C->getRHS();
+
+      return state->BindExpr(C, UndefinedVal(Ex));
+    }
+
+    case Stmt::ChooseExprClass: { // ?:
+
+      ChooseExpr* C = cast<ChooseExpr>(Terminator);
+
+      Expr* Ex = branchTaken ? C->getLHS() : C->getRHS();
+      return state->BindExpr(C, UndefinedVal(Ex));
+    }
+  }
+}
+
+/// RecoverCastedSymbol - A helper function for ProcessBranch that is used
+/// to try to recover some path-sensitivity for casts of symbolic
+/// integers that promote their values (which are currently not tracked well).
+/// This function returns the SVal bound to Condition->IgnoreCasts if all the
+//  cast(s) did was sign-extend the original value.
+static SVal RecoverCastedSymbol(GRStateManager& StateMgr, const GRState* state,
+                                Stmt* Condition, ASTContext& Ctx) {
+
+  Expr *Ex = dyn_cast<Expr>(Condition);
+  if (!Ex)
+    return UnknownVal();
+
+  uint64_t bits = 0;
+  bool bitsInit = false;
+
+  while (CastExpr *CE = dyn_cast<CastExpr>(Ex)) {
+    QualType T = CE->getType();
+
+    if (!T->isIntegerType())
+      return UnknownVal();
+
+    uint64_t newBits = Ctx.getTypeSize(T);
+    if (!bitsInit || newBits < bits) {
+      bitsInit = true;
+      bits = newBits;
+    }
+
+    Ex = CE->getSubExpr();
+  }
+
+  // We reached a non-cast.  Is it a symbolic value?
+  QualType T = Ex->getType();
+
+  if (!bitsInit || !T->isIntegerType() || Ctx.getTypeSize(T) > bits)
+    return UnknownVal();
+
+  return state->getSVal(Ex);
+}
+
+void GRExprEngine::ProcessBranch(Stmt* Condition, Stmt* Term,
+                                 GRBranchNodeBuilder& builder) {
+
+  // Check for NULL conditions; e.g. "for(;;)"
+  if (!Condition) {
+    builder.markInfeasible(false);
+    return;
+  }
+
+  PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
+                                Condition->getLocStart(),
+                                "Error evaluating branch");
+
+  for (CheckersOrdered::iterator I=Checkers.begin(),E=Checkers.end();I!=E;++I) {
+    void *tag = I->first;
+    Checker *checker = I->second;
+    checker->VisitBranchCondition(builder, *this, Condition, tag);
+  }
+
+  // If the branch condition is undefined, return;
+  if (!builder.isFeasible(true) && !builder.isFeasible(false))
+    return;
+
+  const GRState* PrevState = builder.getState();
+  SVal X = PrevState->getSVal(Condition);
+
+  if (X.isUnknown()) {
+    // Give it a chance to recover from unknown.
+    if (const Expr *Ex = dyn_cast<Expr>(Condition)) {
+      if (Ex->getType()->isIntegerType()) {
+        // Try to recover some path-sensitivity.  Right now casts of symbolic
+        // integers that promote their values are currently not tracked well.
+        // If 'Condition' is such an expression, try and recover the
+        // underlying value and use that instead.
+        SVal recovered = RecoverCastedSymbol(getStateManager(),
+                                             builder.getState(), Condition,
+                                             getContext());
+        
+        if (!recovered.isUnknown()) {
+          X = recovered;
+        }
+      }
+    }
+    // If the condition is still unknown, give up.
+    if (X.isUnknown()) {
+      builder.generateNode(MarkBranch(PrevState, Term, true), true);
+      builder.generateNode(MarkBranch(PrevState, Term, false), false);
+      return;
+    }
+  }
+
+  DefinedSVal V = cast<DefinedSVal>(X);
+
+  // Process the true branch.
+  if (builder.isFeasible(true)) {
+    if (const GRState *state = PrevState->Assume(V, true))
+      builder.generateNode(MarkBranch(state, Term, true), true);
+    else
+      builder.markInfeasible(true);
+  }
+
+  // Process the false branch.
+  if (builder.isFeasible(false)) {
+    if (const GRState *state = PrevState->Assume(V, false))
+      builder.generateNode(MarkBranch(state, Term, false), false);
+    else
+      builder.markInfeasible(false);
+  }
+}
+
+/// ProcessIndirectGoto - Called by GRCoreEngine.  Used to generate successor
+///  nodes by processing the 'effects' of a computed goto jump.
+void GRExprEngine::ProcessIndirectGoto(GRIndirectGotoNodeBuilder& builder) {
+
+  const GRState *state = builder.getState();
+  SVal V = state->getSVal(builder.getTarget());
+
+  // Three possibilities:
+  //
+  //   (1) We know the computed label.
+  //   (2) The label is NULL (or some other constant), or Undefined.
+  //   (3) We have no clue about the label.  Dispatch to all targets.
+  //
+
+  typedef GRIndirectGotoNodeBuilder::iterator iterator;
+
+  if (isa<loc::GotoLabel>(V)) {
+    LabelStmt* L = cast<loc::GotoLabel>(V).getLabel();
+
+    for (iterator I=builder.begin(), E=builder.end(); I != E; ++I) {
+      if (I.getLabel() == L) {
+        builder.generateNode(I, state);
+        return;
+      }
+    }
+
+    assert (false && "No block with label.");
+    return;
+  }
+
+  if (isa<loc::ConcreteInt>(V) || isa<UndefinedVal>(V)) {
+    // Dispatch to the first target and mark it as a sink.
+    //ExplodedNode* N = builder.generateNode(builder.begin(), state, true);
+    // FIXME: add checker visit.
+    //    UndefBranches.insert(N);
+    return;
+  }
+
+  // This is really a catch-all.  We don't support symbolics yet.
+  // FIXME: Implement dispatch for symbolic pointers.
+
+  for (iterator I=builder.begin(), E=builder.end(); I != E; ++I)
+    builder.generateNode(I, state);
+}
+
+
+void GRExprEngine::VisitGuardedExpr(Expr* Ex, Expr* L, Expr* R,
+                                    ExplodedNode* Pred, ExplodedNodeSet& Dst) {
+
+  assert(Ex == CurrentStmt && 
+         Pred->getLocationContext()->getCFG()->isBlkExpr(Ex));
+
+  const GRState* state = GetState(Pred);
+  SVal X = state->getSVal(Ex);
+
+  assert (X.isUndef());
+
+  Expr *SE = (Expr*) cast<UndefinedVal>(X).getData();
+  assert(SE);
+  X = state->getSVal(SE);
+
+  // Make sure that we invalidate the previous binding.
+  MakeNode(Dst, Ex, Pred, state->BindExpr(Ex, X, true));
+}
+
+/// ProcessEndPath - Called by GRCoreEngine.  Used to generate end-of-path
+///  nodes when the control reaches the end of a function.
+void GRExprEngine::ProcessEndPath(GREndPathNodeBuilder& builder) {
+  getTF().EvalEndPath(*this, builder);
+  StateMgr.EndPath(builder.getState());
+  for (CheckersOrdered::iterator I=Checkers.begin(),E=Checkers.end(); I!=E;++I){
+    void *tag = I->first;
+    Checker *checker = I->second;
+    checker->EvalEndPath(builder, tag, *this);
+  }
+}
+
+/// ProcessSwitch - Called by GRCoreEngine.  Used to generate successor
+///  nodes by processing the 'effects' of a switch statement.
+void GRExprEngine::ProcessSwitch(GRSwitchNodeBuilder& builder) {
+  typedef GRSwitchNodeBuilder::iterator iterator;
+  const GRState* state = builder.getState();
+  Expr* CondE = builder.getCondition();
+  SVal  CondV_untested = state->getSVal(CondE);
+
+  if (CondV_untested.isUndef()) {
+    //ExplodedNode* N = builder.generateDefaultCaseNode(state, true);
+    // FIXME: add checker 
+    //UndefBranches.insert(N);
+
+    return;
+  }
+  DefinedOrUnknownSVal CondV = cast<DefinedOrUnknownSVal>(CondV_untested);
+
+  const GRState *DefaultSt = state;
+  bool defaultIsFeasible = false;
+
+  for (iterator I = builder.begin(), EI = builder.end(); I != EI; ++I) {
+    CaseStmt* Case = cast<CaseStmt>(I.getCase());
+
+    // Evaluate the LHS of the case value.
+    Expr::EvalResult V1;
+    bool b = Case->getLHS()->Evaluate(V1, getContext());
+
+    // Sanity checks.  These go away in Release builds.
+    assert(b && V1.Val.isInt() && !V1.HasSideEffects
+             && "Case condition must evaluate to an integer constant.");
+    b = b; // silence unused variable warning
+    assert(V1.Val.getInt().getBitWidth() ==
+           getContext().getTypeSize(CondE->getType()));
+
+    // Get the RHS of the case, if it exists.
+    Expr::EvalResult V2;
+
+    if (Expr* E = Case->getRHS()) {
+      b = E->Evaluate(V2, getContext());
+      assert(b && V2.Val.isInt() && !V2.HasSideEffects
+             && "Case condition must evaluate to an integer constant.");
+      b = b; // silence unused variable warning
+    }
+    else
+      V2 = V1;
+
+    // FIXME: Eventually we should replace the logic below with a range
+    //  comparison, rather than concretize the values within the range.
+    //  This should be easy once we have "ranges" for NonLVals.
+
+    do {
+      nonloc::ConcreteInt CaseVal(getBasicVals().getValue(V1.Val.getInt()));
+      DefinedOrUnknownSVal Res = SVator.EvalEQ(DefaultSt ? DefaultSt : state,
+                                               CondV, CaseVal);
+            
+      // Now "assume" that the case matches.
+      if (const GRState* stateNew = state->Assume(Res, true)) {
+        builder.generateCaseStmtNode(I, stateNew);
+
+        // If CondV evaluates to a constant, then we know that this
+        // is the *only* case that we can take, so stop evaluating the
+        // others.
+        if (isa<nonloc::ConcreteInt>(CondV))
+          return;
+      }
+
+      // Now "assume" that the case doesn't match.  Add this state
+      // to the default state (if it is feasible).
+      if (DefaultSt) {
+        if (const GRState *stateNew = DefaultSt->Assume(Res, false)) {
+          defaultIsFeasible = true;
+          DefaultSt = stateNew;
+        }
+        else {
+          defaultIsFeasible = false;
+          DefaultSt = NULL;
+        }
+      }
+        
+      // Concretize the next value in the range.
+      if (V1.Val.getInt() == V2.Val.getInt())
+        break;
+
+      ++V1.Val.getInt();
+      assert (V1.Val.getInt() <= V2.Val.getInt());
+
+    } while (true);
+  }
+
+  // If we reach here, than we know that the default branch is
+  // possible.
+  if (defaultIsFeasible) builder.generateDefaultCaseNode(DefaultSt);
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer functions: logical operations ('&&', '||').
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::VisitLogicalExpr(BinaryOperator* B, ExplodedNode* Pred,
+                                    ExplodedNodeSet& Dst) {
+
+  assert(B->getOpcode() == BinaryOperator::LAnd ||
+         B->getOpcode() == BinaryOperator::LOr);
+
+  assert(B==CurrentStmt && Pred->getLocationContext()->getCFG()->isBlkExpr(B));
+
+  const GRState* state = GetState(Pred);
+  SVal X = state->getSVal(B);
+  assert(X.isUndef());
+
+  const Expr *Ex = (const Expr*) cast<UndefinedVal>(X).getData();
+  assert(Ex);
+
+  if (Ex == B->getRHS()) {
+    X = state->getSVal(Ex);
+
+    // Handle undefined values.
+    if (X.isUndef()) {
+      MakeNode(Dst, B, Pred, state->BindExpr(B, X));
+      return;
+    }
+    
+    DefinedOrUnknownSVal XD = cast<DefinedOrUnknownSVal>(X);
+
+    // We took the RHS.  Because the value of the '&&' or '||' expression must
+    // evaluate to 0 or 1, we must assume the value of the RHS evaluates to 0
+    // or 1.  Alternatively, we could take a lazy approach, and calculate this
+    // value later when necessary.  We don't have the machinery in place for
+    // this right now, and since most logical expressions are used for branches,
+    // the payoff is not likely to be large.  Instead, we do eager evaluation.
+    if (const GRState *newState = state->Assume(XD, true))
+      MakeNode(Dst, B, Pred,
+               newState->BindExpr(B, ValMgr.makeIntVal(1U, B->getType())));
+
+    if (const GRState *newState = state->Assume(XD, false))
+      MakeNode(Dst, B, Pred,
+               newState->BindExpr(B, ValMgr.makeIntVal(0U, B->getType())));
+  }
+  else {
+    // We took the LHS expression.  Depending on whether we are '&&' or
+    // '||' we know what the value of the expression is via properties of
+    // the short-circuiting.
+    X = ValMgr.makeIntVal(B->getOpcode() == BinaryOperator::LAnd ? 0U : 1U,
+                          B->getType());
+    MakeNode(Dst, B, Pred, state->BindExpr(B, X));
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer functions: Loads and stores.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::VisitBlockExpr(BlockExpr *BE, ExplodedNode *Pred,
+                                  ExplodedNodeSet &Dst) {
+  
+  ExplodedNodeSet Tmp;
+  
+  CanQualType T = getContext().getCanonicalType(BE->getType());
+  SVal V = ValMgr.getBlockPointer(BE->getBlockDecl(), T,
+                                  Pred->getLocationContext());
+
+  MakeNode(Tmp, BE, Pred, GetState(Pred)->BindExpr(BE, V),
+           ProgramPoint::PostLValueKind);
+ 
+  // Post-visit the BlockExpr.
+  CheckerVisit(BE, Dst, Tmp, false);
+}
+
+void GRExprEngine::VisitDeclRefExpr(DeclRefExpr *Ex, ExplodedNode *Pred,
+                                    ExplodedNodeSet &Dst, bool asLValue) {
+  VisitCommonDeclRefExpr(Ex, Ex->getDecl(), Pred, Dst, asLValue);
+}
+
+void GRExprEngine::VisitBlockDeclRefExpr(BlockDeclRefExpr *Ex,
+                                         ExplodedNode *Pred,
+                                    ExplodedNodeSet &Dst, bool asLValue) {
+  VisitCommonDeclRefExpr(Ex, Ex->getDecl(), Pred, Dst, asLValue);
+}
+
+void GRExprEngine::VisitCommonDeclRefExpr(Expr *Ex, const NamedDecl *D,
+                                          ExplodedNode *Pred,
+                                          ExplodedNodeSet &Dst, bool asLValue) {
+
+  const GRState *state = GetState(Pred);
+
+  if (const VarDecl* VD = dyn_cast<VarDecl>(D)) {
+
+    SVal V = state->getLValue(VD, Pred->getLocationContext());
+
+    if (asLValue) {
+      // For references, the 'lvalue' is the pointer address stored in the
+      // reference region.
+      if (VD->getType()->isReferenceType()) {
+        if (const MemRegion *R = V.getAsRegion())
+          V = state->getSVal(R);
+        else
+          V = UnknownVal();
+      }
+      
+      MakeNode(Dst, Ex, Pred, state->BindExpr(Ex, V),
+               ProgramPoint::PostLValueKind);
+    }
+    else
+      EvalLoad(Dst, Ex, Pred, state, V);
+
+    return;
+  } else if (const EnumConstantDecl* ED = dyn_cast<EnumConstantDecl>(D)) {
+    assert(!asLValue && "EnumConstantDecl does not have lvalue.");
+
+    SVal V = ValMgr.makeIntVal(ED->getInitVal());
+    MakeNode(Dst, Ex, Pred, state->BindExpr(Ex, V));
+    return;
+
+  } else if (const FunctionDecl* FD = dyn_cast<FunctionDecl>(D)) {
+    // This code is valid regardless of the value of 'isLValue'.
+    SVal V = ValMgr.getFunctionPointer(FD);
+    MakeNode(Dst, Ex, Pred, state->BindExpr(Ex, V),
+             ProgramPoint::PostLValueKind);
+    return;
+  }
+
+  assert (false &&
+          "ValueDecl support for this ValueDecl not implemented.");
+}
+
+/// VisitArraySubscriptExpr - Transfer function for array accesses
+void GRExprEngine::VisitArraySubscriptExpr(ArraySubscriptExpr* A,
+                                           ExplodedNode* Pred,
+                                           ExplodedNodeSet& Dst, bool asLValue){
+
+  Expr* Base = A->getBase()->IgnoreParens();
+  Expr* Idx  = A->getIdx()->IgnoreParens();
+  ExplodedNodeSet Tmp;
+
+  if (Base->getType()->isVectorType()) {
+    // For vector types get its lvalue.
+    // FIXME: This may not be correct.  Is the rvalue of a vector its location?
+    //  In fact, I think this is just a hack.  We need to get the right
+    // semantics.
+    VisitLValue(Base, Pred, Tmp);
+  }
+  else
+    Visit(Base, Pred, Tmp);   // Get Base's rvalue, which should be an LocVal.
+
+  for (ExplodedNodeSet::iterator I1=Tmp.begin(), E1=Tmp.end(); I1!=E1; ++I1) {
+    ExplodedNodeSet Tmp2;
+    Visit(Idx, *I1, Tmp2);     // Evaluate the index.
+
+    ExplodedNodeSet Tmp3;
+    CheckerVisit(A, Tmp3, Tmp2, true);
+
+    for (ExplodedNodeSet::iterator I2=Tmp3.begin(),E2=Tmp3.end();I2!=E2; ++I2) {
+      const GRState* state = GetState(*I2);
+      SVal V = state->getLValue(A->getType(), state->getSVal(Idx),
+                                state->getSVal(Base));
+
+      if (asLValue)
+        MakeNode(Dst, A, *I2, state->BindExpr(A, V),
+                 ProgramPoint::PostLValueKind);
+      else
+        EvalLoad(Dst, A, *I2, state, V);
+    }
+  }
+}
+
+/// VisitMemberExpr - Transfer function for member expressions.
+void GRExprEngine::VisitMemberExpr(MemberExpr* M, ExplodedNode* Pred,
+                                   ExplodedNodeSet& Dst, bool asLValue) {
+
+  Expr* Base = M->getBase()->IgnoreParens();
+  ExplodedNodeSet Tmp;
+
+  if (M->isArrow())
+    Visit(Base, Pred, Tmp);        // p->f = ...  or   ... = p->f
+  else
+    VisitLValue(Base, Pred, Tmp);  // x.f = ...   or   ... = x.f
+
+  FieldDecl *Field = dyn_cast<FieldDecl>(M->getMemberDecl());
+  if (!Field) // FIXME: skipping member expressions for non-fields
+    return;
+
+  for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; ++I) {
+    const GRState* state = GetState(*I);
+    // FIXME: Should we insert some assumption logic in here to determine
+    // if "Base" is a valid piece of memory?  Before we put this assumption
+    // later when using FieldOffset lvals (which we no longer have).
+    SVal L = state->getLValue(Field, state->getSVal(Base));
+
+    if (asLValue)
+      MakeNode(Dst, M, *I, state->BindExpr(M, L), ProgramPoint::PostLValueKind);
+    else
+      EvalLoad(Dst, M, *I, state, L);
+  }
+}
+
+/// EvalBind - Handle the semantics of binding a value to a specific location.
+///  This method is used by EvalStore and (soon) VisitDeclStmt, and others.
+void GRExprEngine::EvalBind(ExplodedNodeSet& Dst, Stmt *AssignE,
+                            Stmt* StoreE, ExplodedNode* Pred,
+                            const GRState* state, SVal location, SVal Val,
+                            bool atDeclInit) {
+  
+  
+  // Do a previsit of the bind.
+  ExplodedNodeSet CheckedSet, Src;
+  Src.Add(Pred);
+  CheckerVisitBind(AssignE, StoreE, CheckedSet, Src, location, Val, true);
+  
+  for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
+       I!=E; ++I) {
+    
+    if (Pred != *I)
+      state = GetState(*I);
+    
+    const GRState* newState = 0;
+
+    if (atDeclInit) {
+      const VarRegion *VR =
+        cast<VarRegion>(cast<loc::MemRegionVal>(location).getRegion());
+
+      newState = state->bindDecl(VR, Val);
+    }
+    else {
+      if (location.isUnknown()) {
+        // We know that the new state will be the same as the old state since
+        // the location of the binding is "unknown".  Consequently, there
+        // is no reason to just create a new node.
+        newState = state;
+      }
+      else {
+        // We are binding to a value other than 'unknown'.  Perform the binding
+        // using the StoreManager.
+        newState = state->bindLoc(cast<Loc>(location), Val);
+      }
+    }
+
+    // The next thing to do is check if the GRTransferFuncs object wants to
+    // update the state based on the new binding.  If the GRTransferFunc object
+    // doesn't do anything, just auto-propagate the current state.
+    GRStmtNodeBuilderRef BuilderRef(Dst, *Builder, *this, *I, newState, StoreE,
+                                    newState != state);
+
+    getTF().EvalBind(BuilderRef, location, Val);
+  }
+}
+
+/// EvalStore - Handle the semantics of a store via an assignment.
+///  @param Dst The node set to store generated state nodes
+///  @param Ex The expression representing the location of the store
+///  @param state The current simulation state
+///  @param location The location to store the value
+///  @param Val The value to be stored
+void GRExprEngine::EvalStore(ExplodedNodeSet& Dst, Expr *AssignE,
+                             Expr* StoreE,
+                             ExplodedNode* Pred,
+                             const GRState* state, SVal location, SVal Val,
+                             const void *tag) {
+
+  assert(Builder && "GRStmtNodeBuilder must be defined.");
+
+  // Evaluate the location (checks for bad dereferences).
+  ExplodedNodeSet Tmp;
+  EvalLocation(Tmp, StoreE, Pred, state, location, tag, false);
+
+  if (Tmp.empty())
+    return;
+
+  assert(!location.isUndef());
+
+  SaveAndRestore<ProgramPoint::Kind> OldSPointKind(Builder->PointKind,
+                                                   ProgramPoint::PostStoreKind);
+  SaveAndRestore<const void*> OldTag(Builder->Tag, tag);
+  
+  // Proceed with the store.
+  for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI)
+    EvalBind(Dst, AssignE, StoreE, *NI, GetState(*NI), location, Val);
+}
+
+void GRExprEngine::EvalLoad(ExplodedNodeSet& Dst, Expr *Ex, ExplodedNode* Pred,
+                            const GRState* state, SVal location,
+                            const void *tag, QualType LoadTy) {
+
+  // Are we loading from a region?  This actually results in two loads; one
+  // to fetch the address of the referenced value and one to fetch the
+  // referenced value.
+  if (const TypedRegion *TR = 
+        dyn_cast_or_null<TypedRegion>(location.getAsRegion())) {
+    
+    QualType ValTy = TR->getValueType(getContext());
+    if (const ReferenceType *RT = ValTy->getAs<ReferenceType>()) {
+      static int loadReferenceTag = 0;    
+      ExplodedNodeSet Tmp;
+      EvalLoadCommon(Tmp, Ex, Pred, state, location, &loadReferenceTag,
+                     getContext().getPointerType(RT->getPointeeType()));
+
+      // Perform the load from the referenced value.
+      for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end() ; I!=E; ++I) {
+        state = GetState(*I);
+        location = state->getSVal(Ex);
+        EvalLoadCommon(Dst, Ex, *I, state, location, tag, LoadTy);
+      }    
+      return;
+    }
+  }
+  
+  EvalLoadCommon(Dst, Ex, Pred, state, location, tag, LoadTy);
+}
+
+void GRExprEngine::EvalLoadCommon(ExplodedNodeSet& Dst, Expr *Ex,
+                                  ExplodedNode* Pred,
+                                  const GRState* state, SVal location,
+                                  const void *tag, QualType LoadTy) {
+  
+  // Evaluate the location (checks for bad dereferences).
+  ExplodedNodeSet Tmp;
+  EvalLocation(Tmp, Ex, Pred, state, location, tag, true);
+
+  if (Tmp.empty())
+    return;
+  
+  assert(!location.isUndef());
+  
+  SaveAndRestore<ProgramPoint::Kind> OldSPointKind(Builder->PointKind);
+  SaveAndRestore<const void*> OldTag(Builder->Tag);
+
+  // Proceed with the load.
+  for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI) {
+    state = GetState(*NI);
+    if (location.isUnknown()) {
+      // This is important.  We must nuke the old binding.
+      MakeNode(Dst, Ex, *NI, state->BindExpr(Ex, UnknownVal()),
+               ProgramPoint::PostLoadKind, tag);
+    }
+    else {
+      SVal V = state->getSVal(cast<Loc>(location), LoadTy.isNull() ? 
+                                                     Ex->getType() : LoadTy);
+      MakeNode(Dst, Ex, *NI, state->BindExpr(Ex, V), ProgramPoint::PostLoadKind,
+               tag);
+    }
+  }
+}
+
+void GRExprEngine::EvalLocation(ExplodedNodeSet &Dst, Stmt *S,
+                                ExplodedNode* Pred,
+                                const GRState* state, SVal location,
+                                const void *tag, bool isLoad) {
+  // Early checks for performance reason.
+  if (location.isUnknown() || Checkers.empty()) {
+    Dst.Add(Pred);
+    return;
+  }
+  
+  ExplodedNodeSet Src, Tmp;
+  Src.Add(Pred);
+  ExplodedNodeSet *PrevSet = &Src;
+  
+  for (CheckersOrdered::iterator I=Checkers.begin(),E=Checkers.end(); I!=E; ++I)
+  {
+    ExplodedNodeSet *CurrSet = 0;
+    if (I+1 == E)
+      CurrSet = &Dst;
+    else {
+      CurrSet = (PrevSet == &Tmp) ? &Src : &Tmp;
+      CurrSet->clear();
+    }
+    
+    void *tag = I->first;
+    Checker *checker = I->second;
+    
+    for (ExplodedNodeSet::iterator NI = PrevSet->begin(), NE = PrevSet->end();
+         NI != NE; ++NI) {
+      // Use the 'state' argument only when the predecessor node is the
+      // same as Pred.  This allows us to catch updates to the state.
+      checker->GR_VisitLocation(*CurrSet, *Builder, *this, S, *NI,
+                                *NI == Pred ? state : GetState(*NI),
+                                location, tag, isLoad);
+    }
+    
+    // Update which NodeSet is the current one.
+    PrevSet = CurrSet;
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function: Function calls.
+//===----------------------------------------------------------------------===//
+
+namespace {
+class CallExprWLItem {
+public:
+  CallExpr::arg_iterator I;
+  ExplodedNode *N;
+
+  CallExprWLItem(const CallExpr::arg_iterator &i, ExplodedNode *n)
+    : I(i), N(n) {}
+};  
+} // end anonymous namespace
+
+void GRExprEngine::VisitCall(CallExpr* CE, ExplodedNode* Pred,
+                             CallExpr::arg_iterator AI,
+                             CallExpr::arg_iterator AE,
+                             ExplodedNodeSet& Dst, bool asLValue) {
+
+  // Determine the type of function we're calling (if available).
+  const FunctionProtoType *Proto = NULL;
+  QualType FnType = CE->getCallee()->IgnoreParens()->getType();
+  if (const PointerType *FnTypePtr = FnType->getAs<PointerType>())
+    Proto = FnTypePtr->getPointeeType()->getAs<FunctionProtoType>();
+
+  // Create a worklist to process the arguments.
+  llvm::SmallVector<CallExprWLItem, 20> WorkList;
+  WorkList.reserve(AE - AI);
+  WorkList.push_back(CallExprWLItem(AI, Pred));
+  
+  ExplodedNodeSet ArgsEvaluated;
+
+  while (!WorkList.empty()) {
+    CallExprWLItem Item = WorkList.back();
+    WorkList.pop_back();
+    
+    if (Item.I == AE) {
+      ArgsEvaluated.insert(Item.N);
+      continue;
+    }
+    
+    // Evaluate the argument.
+    ExplodedNodeSet Tmp;
+    const unsigned ParamIdx = Item.I - AI;
+    
+    bool VisitAsLvalue = false;
+    if (Proto && ParamIdx < Proto->getNumArgs())
+      VisitAsLvalue = Proto->getArgType(ParamIdx)->isReferenceType();
+    
+    if (VisitAsLvalue)
+      VisitLValue(*Item.I, Item.N, Tmp);
+    else
+      Visit(*Item.I, Item.N, Tmp);
+   
+    // Enqueue evaluating the next argument on the worklist.
+    ++(Item.I);
+
+    for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI)
+      WorkList.push_back(CallExprWLItem(Item.I, *NI));
+  }
+
+  // Now process the call itself.
+  ExplodedNodeSet DstTmp;
+  Expr* Callee = CE->getCallee()->IgnoreParens();
+  
+  for (ExplodedNodeSet::iterator NI=ArgsEvaluated.begin(),
+                                 NE=ArgsEvaluated.end(); NI != NE; ++NI) {
+    // Evaluate the callee.
+    ExplodedNodeSet DstTmp2;
+    Visit(Callee, *NI, DstTmp2);    
+    // Perform the previsit of the CallExpr, storing the results in DstTmp.
+    CheckerVisit(CE, DstTmp, DstTmp2, true);
+  }
+  
+  // Finally, evaluate the function call.  We try each of the checkers
+  // to see if the can evaluate the function call.
+  ExplodedNodeSet DstTmp3;
+
+  
+  for (ExplodedNodeSet::iterator DI = DstTmp.begin(), DE = DstTmp.end();
+       DI != DE; ++DI) {
+    
+    const GRState* state = GetState(*DI);
+    SVal L = state->getSVal(Callee);
+    
+    // FIXME: Add support for symbolic function calls (calls involving
+    //  function pointer values that are symbolic).
+    SaveAndRestore<bool> OldSink(Builder->BuildSinks);
+    ExplodedNodeSet DstChecker;
+    
+    // If the callee is processed by a checker, skip the rest logic.
+    if (CheckerEvalCall(CE, DstChecker, *DI))
+      DstTmp3.insert(DstChecker);
+    else {
+      for (ExplodedNodeSet::iterator DI_Checker = DstChecker.begin(),
+           DE_Checker = DstChecker.end();
+           DI_Checker != DE_Checker; ++DI_Checker) {
+        
+        // Dispatch to the plug-in transfer function.
+        unsigned OldSize = DstTmp3.size();
+        SaveOr OldHasGen(Builder->HasGeneratedNode);
+        Pred = *DI_Checker;
+        
+        // Dispatch to transfer function logic to handle the call itself.
+        // FIXME: Allow us to chain together transfer functions.
+        assert(Builder && "GRStmtNodeBuilder must be defined.");        
+        getTF().EvalCall(DstTmp3, *this, *Builder, CE, L, Pred);
+        
+        // Handle the case where no nodes where generated.  Auto-generate that
+        // contains the updated state if we aren't generating sinks.
+        if (!Builder->BuildSinks && DstTmp3.size() == OldSize &&
+            !Builder->HasGeneratedNode)
+          MakeNode(DstTmp3, CE, Pred, state);
+      }
+    }
+  }
+  
+  // Finally, perform the post-condition check of the CallExpr and store
+  // the created nodes in 'Dst'.
+  
+  if (!(!asLValue && CalleeReturnsReference(CE))) {
+    CheckerVisit(CE, Dst, DstTmp3, false);
+    return;
+  }
+  
+  // Handle the case where the called function returns a reference but
+  // we expect an rvalue.  For such cases, convert the reference to
+  // an rvalue.  
+  // FIXME: This conversion doesn't actually happen unless the result
+  //  of CallExpr is consumed by another expression.
+  ExplodedNodeSet DstTmp4;
+  CheckerVisit(CE, DstTmp4, DstTmp3, false);
+  QualType LoadTy = CE->getType();
+  
+  static int *ConvertToRvalueTag = 0;
+  for (ExplodedNodeSet::iterator NI = DstTmp4.begin(), NE = DstTmp4.end();
+       NI!=NE; ++NI) {
+    const GRState *state = GetState(*NI);
+    EvalLoad(Dst, CE, *NI, state, state->getSVal(CE),
+             &ConvertToRvalueTag, LoadTy);
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function: Objective-C ivar references.
+//===----------------------------------------------------------------------===//
+
+static std::pair<const void*,const void*> EagerlyAssumeTag
+  = std::pair<const void*,const void*>(&EagerlyAssumeTag,0);
+
+void GRExprEngine::EvalEagerlyAssume(ExplodedNodeSet &Dst, ExplodedNodeSet &Src,
+                                     Expr *Ex) {
+  for (ExplodedNodeSet::iterator I=Src.begin(), E=Src.end(); I!=E; ++I) {
+    ExplodedNode *Pred = *I;
+
+    // Test if the previous node was as the same expression.  This can happen
+    // when the expression fails to evaluate to anything meaningful and
+    // (as an optimization) we don't generate a node.
+    ProgramPoint P = Pred->getLocation();
+    if (!isa<PostStmt>(P) || cast<PostStmt>(P).getStmt() != Ex) {
+      Dst.Add(Pred);
+      continue;
+    }
+
+    const GRState* state = Pred->getState();
+    SVal V = state->getSVal(Ex);
+    if (nonloc::SymExprVal *SEV = dyn_cast<nonloc::SymExprVal>(&V)) {
+      // First assume that the condition is true.
+      if (const GRState *stateTrue = state->Assume(*SEV, true)) {
+        stateTrue = stateTrue->BindExpr(Ex,
+                                        ValMgr.makeIntVal(1U, Ex->getType()));
+        Dst.Add(Builder->generateNode(PostStmtCustom(Ex,
+                                &EagerlyAssumeTag, Pred->getLocationContext()),
+                                      stateTrue, Pred));
+      }
+
+      // Next, assume that the condition is false.
+      if (const GRState *stateFalse = state->Assume(*SEV, false)) {
+        stateFalse = stateFalse->BindExpr(Ex,
+                                          ValMgr.makeIntVal(0U, Ex->getType()));
+        Dst.Add(Builder->generateNode(PostStmtCustom(Ex, &EagerlyAssumeTag,
+                                                   Pred->getLocationContext()),
+                                      stateFalse, Pred));
+      }
+    }
+    else
+      Dst.Add(Pred);
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function: Objective-C ivar references.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::VisitObjCIvarRefExpr(ObjCIvarRefExpr* Ex, ExplodedNode* Pred,
+                                        ExplodedNodeSet& Dst, bool asLValue) {
+
+  Expr* Base = cast<Expr>(Ex->getBase());
+  ExplodedNodeSet Tmp;
+  Visit(Base, Pred, Tmp);
+
+  for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+    const GRState* state = GetState(*I);
+    SVal BaseVal = state->getSVal(Base);
+    SVal location = state->getLValue(Ex->getDecl(), BaseVal);
+
+    if (asLValue)
+      MakeNode(Dst, Ex, *I, state->BindExpr(Ex, location));
+    else
+      EvalLoad(Dst, Ex, *I, state, location);
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function: Objective-C fast enumeration 'for' statements.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S,
+                                     ExplodedNode* Pred, ExplodedNodeSet& Dst) {
+
+  // ObjCForCollectionStmts are processed in two places.  This method
+  // handles the case where an ObjCForCollectionStmt* occurs as one of the
+  // statements within a basic block.  This transfer function does two things:
+  //
+  //  (1) binds the next container value to 'element'.  This creates a new
+  //      node in the ExplodedGraph.
+  //
+  //  (2) binds the value 0/1 to the ObjCForCollectionStmt* itself, indicating
+  //      whether or not the container has any more elements.  This value
+  //      will be tested in ProcessBranch.  We need to explicitly bind
+  //      this value because a container can contain nil elements.
+  //
+  // FIXME: Eventually this logic should actually do dispatches to
+  //   'countByEnumeratingWithState:objects:count:' (NSFastEnumeration).
+  //   This will require simulating a temporary NSFastEnumerationState, either
+  //   through an SVal or through the use of MemRegions.  This value can
+  //   be affixed to the ObjCForCollectionStmt* instead of 0/1; when the loop
+  //   terminates we reclaim the temporary (it goes out of scope) and we
+  //   we can test if the SVal is 0 or if the MemRegion is null (depending
+  //   on what approach we take).
+  //
+  //  For now: simulate (1) by assigning either a symbol or nil if the
+  //    container is empty.  Thus this transfer function will by default
+  //    result in state splitting.
+
+  Stmt* elem = S->getElement();
+  SVal ElementV;
+
+  if (DeclStmt* DS = dyn_cast<DeclStmt>(elem)) {
+    VarDecl* ElemD = cast<VarDecl>(DS->getSingleDecl());
+    assert (ElemD->getInit() == 0);
+    ElementV = GetState(Pred)->getLValue(ElemD, Pred->getLocationContext());
+    VisitObjCForCollectionStmtAux(S, Pred, Dst, ElementV);
+    return;
+  }
+
+  ExplodedNodeSet Tmp;
+  VisitLValue(cast<Expr>(elem), Pred, Tmp);
+
+  for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I!=E; ++I) {
+    const GRState* state = GetState(*I);
+    VisitObjCForCollectionStmtAux(S, *I, Dst, state->getSVal(elem));
+  }
+}
+
+void GRExprEngine::VisitObjCForCollectionStmtAux(ObjCForCollectionStmt* S,
+                                       ExplodedNode* Pred, ExplodedNodeSet& Dst,
+                                                 SVal ElementV) {
+
+  // Check if the location we are writing back to is a null pointer.
+  Stmt* elem = S->getElement();
+  ExplodedNodeSet Tmp;
+  EvalLocation(Tmp, elem, Pred, GetState(Pred), ElementV, NULL, false);
+  
+  if (Tmp.empty())
+    return;
+  
+  for (ExplodedNodeSet::iterator NI=Tmp.begin(), NE=Tmp.end(); NI!=NE; ++NI) {
+    Pred = *NI;
+    const GRState *state = GetState(Pred);
+
+    // Handle the case where the container still has elements.
+    SVal TrueV = ValMgr.makeTruthVal(1);
+    const GRState *hasElems = state->BindExpr(S, TrueV);
+
+    // Handle the case where the container has no elements.
+    SVal FalseV = ValMgr.makeTruthVal(0);
+    const GRState *noElems = state->BindExpr(S, FalseV);
+
+    if (loc::MemRegionVal* MV = dyn_cast<loc::MemRegionVal>(&ElementV))
+      if (const TypedRegion* R = dyn_cast<TypedRegion>(MV->getRegion())) {
+        // FIXME: The proper thing to do is to really iterate over the
+        //  container.  We will do this with dispatch logic to the store.
+        //  For now, just 'conjure' up a symbolic value.
+        QualType T = R->getValueType(getContext());
+        assert(Loc::IsLocType(T));
+        unsigned Count = Builder->getCurrentBlockCount();
+        SymbolRef Sym = SymMgr.getConjuredSymbol(elem, T, Count);
+        SVal V = ValMgr.makeLoc(Sym);
+        hasElems = hasElems->bindLoc(ElementV, V);
+
+        // Bind the location to 'nil' on the false branch.
+        SVal nilV = ValMgr.makeIntVal(0, T);
+        noElems = noElems->bindLoc(ElementV, nilV);
+      }
+
+    // Create the new nodes.
+    MakeNode(Dst, S, Pred, hasElems);
+    MakeNode(Dst, S, Pred, noElems);
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer function: Objective-C message expressions.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::VisitObjCMessageExpr(ObjCMessageExpr* ME, ExplodedNode* Pred,
+                                        ExplodedNodeSet& Dst, bool asLValue){
+
+  VisitObjCMessageExprArgHelper(ME, ME->arg_begin(), ME->arg_end(),
+                                Pred, Dst, asLValue);
+}
+
+void GRExprEngine::VisitObjCMessageExprArgHelper(ObjCMessageExpr* ME,
+                                               ObjCMessageExpr::arg_iterator AI,
+                                               ObjCMessageExpr::arg_iterator AE,
+                                                 ExplodedNode* Pred,
+                                                 ExplodedNodeSet& Dst,
+                                                 bool asLValue) {
+  if (AI == AE) {
+
+    // Process the receiver.
+
+    if (Expr* Receiver = ME->getReceiver()) {
+      ExplodedNodeSet Tmp;
+      Visit(Receiver, Pred, Tmp);
+
+      for (ExplodedNodeSet::iterator NI = Tmp.begin(), NE = Tmp.end(); NI != NE;
+           ++NI)
+        VisitObjCMessageExprDispatchHelper(ME, *NI, Dst, asLValue);
+
+      return;
+    }
+
+    VisitObjCMessageExprDispatchHelper(ME, Pred, Dst, asLValue);
+    return;
+  }
+
+  ExplodedNodeSet Tmp;
+  Visit(*AI, Pred, Tmp);
+
+  ++AI;
+
+  for (ExplodedNodeSet::iterator NI = Tmp.begin(), NE = Tmp.end();NI != NE;++NI)
+    VisitObjCMessageExprArgHelper(ME, AI, AE, *NI, Dst, asLValue);
+}
+
+void GRExprEngine::VisitObjCMessageExprDispatchHelper(ObjCMessageExpr* ME,
+                                                      ExplodedNode* Pred,
+                                                      ExplodedNodeSet& Dst,
+                                                      bool asLValue) {
+
+  // Handle previsits checks.
+  ExplodedNodeSet Src, DstTmp;
+  Src.Add(Pred);
+  
+  CheckerVisit(ME, DstTmp, Src, true);
+  
+  ExplodedNodeSet PostVisitSrc;
+
+  for (ExplodedNodeSet::iterator DI = DstTmp.begin(), DE = DstTmp.end();
+       DI!=DE; ++DI) {    
+
+    Pred = *DI;
+    bool RaisesException = false;
+    
+    unsigned OldSize = PostVisitSrc.size();
+    SaveAndRestore<bool> OldSink(Builder->BuildSinks);
+    SaveOr OldHasGen(Builder->HasGeneratedNode);  
+
+    if (const Expr *Receiver = ME->getReceiver()) {
+      const GRState *state = Pred->getState();
+
+      // Bifurcate the state into nil and non-nil ones.
+      DefinedOrUnknownSVal receiverVal = 
+        cast<DefinedOrUnknownSVal>(state->getSVal(Receiver));
+
+      const GRState *notNilState, *nilState;
+      llvm::tie(notNilState, nilState) = state->Assume(receiverVal);
+
+      // There are three cases: can be nil or non-nil, must be nil, must be 
+      // non-nil. We handle must be nil, and merge the rest two into non-nil.
+      if (nilState && !notNilState) {
+        CheckerEvalNilReceiver(ME, PostVisitSrc, nilState, Pred);
+        continue;
+      }
+
+      assert(notNilState);
+
+      // Check if the "raise" message was sent.
+      if (ME->getSelector() == RaiseSel)
+        RaisesException = true;
+
+      // Check if we raise an exception.  For now treat these as sinks.
+      // Eventually we will want to handle exceptions properly.
+      if (RaisesException)
+        Builder->BuildSinks = true;
+
+      // Dispatch to plug-in transfer function.
+      EvalObjCMessageExpr(PostVisitSrc, ME, Pred, notNilState);
+    }
+    else {
+      IdentifierInfo* ClsName = ME->getClassName();
+      Selector S = ME->getSelector();
+
+      // Check for special instance methods.
+      if (!NSExceptionII) {
+        ASTContext& Ctx = getContext();
+        NSExceptionII = &Ctx.Idents.get("NSException");
+      }
+
+      if (ClsName == NSExceptionII) {
+        enum { NUM_RAISE_SELECTORS = 2 };
+
+        // Lazily create a cache of the selectors.
+        if (!NSExceptionInstanceRaiseSelectors) {
+          ASTContext& Ctx = getContext();
+          NSExceptionInstanceRaiseSelectors = new Selector[NUM_RAISE_SELECTORS];
+          llvm::SmallVector<IdentifierInfo*, NUM_RAISE_SELECTORS> II;
+          unsigned idx = 0;
+
+          // raise:format:
+          II.push_back(&Ctx.Idents.get("raise"));
+          II.push_back(&Ctx.Idents.get("format"));
+          NSExceptionInstanceRaiseSelectors[idx++] =
+            Ctx.Selectors.getSelector(II.size(), &II[0]);
+
+          // raise:format::arguments:
+          II.push_back(&Ctx.Idents.get("arguments"));
+          NSExceptionInstanceRaiseSelectors[idx++] =
+            Ctx.Selectors.getSelector(II.size(), &II[0]);
+        }
+
+        for (unsigned i = 0; i < NUM_RAISE_SELECTORS; ++i)
+          if (S == NSExceptionInstanceRaiseSelectors[i]) {
+            RaisesException = true;
+            break;
+          }
+      }
+
+      // Check if we raise an exception.  For now treat these as sinks.
+      // Eventually we will want to handle exceptions properly.
+      if (RaisesException)
+        Builder->BuildSinks = true;
+
+      // Dispatch to plug-in transfer function.
+      EvalObjCMessageExpr(PostVisitSrc, ME, Pred, Builder->GetState(Pred));
+    }
+    
+    // Handle the case where no nodes where generated.  Auto-generate that
+    // contains the updated state if we aren't generating sinks.
+    if (!Builder->BuildSinks && PostVisitSrc.size() == OldSize &&
+        !Builder->HasGeneratedNode)
+      MakeNode(PostVisitSrc, ME, Pred, GetState(Pred));
+  }
+
+  // Finally, perform the post-condition check of the ObjCMessageExpr and store
+  // the created nodes in 'Dst'.
+  if (!(!asLValue && ReceiverReturnsReference(ME))) {
+    CheckerVisit(ME, Dst, PostVisitSrc, false);
+    return;
+  }
+  
+  // Handle the case where the message expression returns a reference but
+  // we expect an rvalue.  For such cases, convert the reference to
+  // an rvalue.  
+  // FIXME: This conversion doesn't actually happen unless the result
+  //  of ObjCMessageExpr is consumed by another expression.
+  ExplodedNodeSet DstRValueConvert;
+  CheckerVisit(ME, DstRValueConvert, PostVisitSrc, false);
+  QualType LoadTy = ME->getType();
+  
+  static int *ConvertToRvalueTag = 0;
+  for (ExplodedNodeSet::iterator NI = DstRValueConvert.begin(),
+       NE = DstRValueConvert.end();
+       NI!=NE; ++NI) {
+    const GRState *state = GetState(*NI);
+    EvalLoad(Dst, ME, *NI, state, state->getSVal(ME),
+             &ConvertToRvalueTag, LoadTy);
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer functions: Miscellaneous statements.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::VisitCast(CastExpr *CastE, Expr *Ex, ExplodedNode *Pred, 
+                             ExplodedNodeSet &Dst, bool asLValue) {
+  ExplodedNodeSet S1;
+  QualType T = CastE->getType();
+  QualType ExTy = Ex->getType();
+
+  if (const ExplicitCastExpr *ExCast=dyn_cast_or_null<ExplicitCastExpr>(CastE))
+    T = ExCast->getTypeAsWritten();
+
+  if (ExTy->isArrayType() || ExTy->isFunctionType() || T->isReferenceType() ||
+      asLValue)
+    VisitLValue(Ex, Pred, S1);
+  else
+    Visit(Ex, Pred, S1);
+
+  ExplodedNodeSet S2;
+  CheckerVisit(CastE, S2, S1, true);
+
+  // If we are evaluating the cast in an lvalue context, we implicitly want
+  // the cast to evaluate to a location.
+  if (asLValue) {
+    ASTContext &Ctx = getContext();
+    T = Ctx.getPointerType(Ctx.getCanonicalType(T));
+    ExTy = Ctx.getPointerType(Ctx.getCanonicalType(ExTy));
+  }
+
+  switch (CastE->getCastKind()) {
+  case CastExpr::CK_ToVoid:
+    assert(!asLValue);
+    for (ExplodedNodeSet::iterator I = S2.begin(), E = S2.end(); I != E; ++I)
+      Dst.Add(*I);
+    return;
+
+  case CastExpr::CK_NoOp:
+  case CastExpr::CK_FunctionToPointerDecay:
+    for (ExplodedNodeSet::iterator I = S2.begin(), E = S2.end(); I != E; ++I) {
+      // Copy the SVal of Ex to CastE.
+      ExplodedNode *N = *I;
+      const GRState *state = GetState(N);
+      SVal V = state->getSVal(Ex);
+      state = state->BindExpr(CastE, V);
+      MakeNode(Dst, CastE, N, state);
+    }
+    return;
+
+  case CastExpr::CK_Unknown:
+  case CastExpr::CK_ArrayToPointerDecay:
+  case CastExpr::CK_BitCast:
+  case CastExpr::CK_IntegralCast:
+  case CastExpr::CK_IntegralToPointer:
+  case CastExpr::CK_PointerToIntegral:
+  case CastExpr::CK_IntegralToFloating:
+  case CastExpr::CK_FloatingToIntegral:
+  case CastExpr::CK_FloatingCast:
+  case CastExpr::CK_AnyPointerToObjCPointerCast:
+  case CastExpr::CK_AnyPointerToBlockPointerCast:
+  case CastExpr::CK_DerivedToBase:
+    // Delegate to SValuator to process.
+    for (ExplodedNodeSet::iterator I = S2.begin(), E = S2.end(); I != E; ++I) {
+      ExplodedNode* N = *I;
+      const GRState* state = GetState(N);
+      SVal V = state->getSVal(Ex);
+      V = SVator.EvalCast(V, T, ExTy);
+      state = state->BindExpr(CastE, V);
+      MakeNode(Dst, CastE, N, state);
+    }
+    return;
+
+  default:
+    llvm::errs() << "Cast kind " << CastE->getCastKind() << " not handled.\n";
+    assert(0);
+  }
+}
+
+void GRExprEngine::VisitCompoundLiteralExpr(CompoundLiteralExpr* CL,
+                                            ExplodedNode* Pred,
+                                            ExplodedNodeSet& Dst,
+                                            bool asLValue) {
+  InitListExpr* ILE = cast<InitListExpr>(CL->getInitializer()->IgnoreParens());
+  ExplodedNodeSet Tmp;
+  Visit(ILE, Pred, Tmp);
+
+  for (ExplodedNodeSet::iterator I = Tmp.begin(), EI = Tmp.end(); I!=EI; ++I) {
+    const GRState* state = GetState(*I);
+    SVal ILV = state->getSVal(ILE);
+    const LocationContext *LC = (*I)->getLocationContext();
+    state = state->bindCompoundLiteral(CL, LC, ILV);
+
+    if (asLValue) {
+      MakeNode(Dst, CL, *I, state->BindExpr(CL, state->getLValue(CL, LC)));
+    }
+    else
+      MakeNode(Dst, CL, *I, state->BindExpr(CL, ILV));
+  }
+}
+
+void GRExprEngine::VisitDeclStmt(DeclStmt *DS, ExplodedNode *Pred,
+                                 ExplodedNodeSet& Dst) {
+
+  // The CFG has one DeclStmt per Decl.
+  Decl* D = *DS->decl_begin();
+
+  if (!D || !isa<VarDecl>(D))
+    return;
+
+  const VarDecl* VD = dyn_cast<VarDecl>(D);
+  Expr* InitEx = const_cast<Expr*>(VD->getInit());
+
+  // FIXME: static variables may have an initializer, but the second
+  //  time a function is called those values may not be current.
+  ExplodedNodeSet Tmp;
+
+  if (InitEx) {
+    if (VD->getType()->isReferenceType())
+      VisitLValue(InitEx, Pred, Tmp);
+    else
+      Visit(InitEx, Pred, Tmp);
+  }
+  else
+    Tmp.Add(Pred);
+
+  ExplodedNodeSet Tmp2;
+  CheckerVisit(DS, Tmp2, Tmp, true);
+  
+  for (ExplodedNodeSet::iterator I=Tmp2.begin(), E=Tmp2.end(); I!=E; ++I) {
+    ExplodedNode *N = *I;
+    const GRState *state = GetState(N);
+
+    // Decls without InitExpr are not initialized explicitly.
+    const LocationContext *LC = N->getLocationContext();
+
+    if (InitEx) {
+      SVal InitVal = state->getSVal(InitEx);
+
+      // Recover some path-sensitivity if a scalar value evaluated to
+      // UnknownVal.
+      if (InitVal.isUnknown() ||
+          !getConstraintManager().canReasonAbout(InitVal)) {
+        InitVal = ValMgr.getConjuredSymbolVal(NULL, InitEx, 
+                                               Builder->getCurrentBlockCount());
+      }
+      
+      EvalBind(Dst, DS, DS, *I, state,
+               loc::MemRegionVal(state->getRegion(VD, LC)), InitVal, true);   
+    }
+    else {
+      state = state->bindDeclWithNoInit(state->getRegion(VD, LC));
+      MakeNode(Dst, DS, *I, state);
+    }
+  }
+}
+
+void GRExprEngine::VisitCondInit(VarDecl *VD, Stmt *S,
+                                 ExplodedNode *Pred, ExplodedNodeSet& Dst) {
+  
+  Expr* InitEx = VD->getInit();  
+  ExplodedNodeSet Tmp;
+  Visit(InitEx, Pred, Tmp);
+
+  for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+    ExplodedNode *N = *I;
+    const GRState *state = GetState(N);
+    
+    const LocationContext *LC = N->getLocationContext();
+    SVal InitVal = state->getSVal(InitEx);
+      
+    // Recover some path-sensitivity if a scalar value evaluated to
+    // UnknownVal.
+    if (InitVal.isUnknown() ||
+        !getConstraintManager().canReasonAbout(InitVal)) {
+      InitVal = ValMgr.getConjuredSymbolVal(NULL, InitEx, 
+                                            Builder->getCurrentBlockCount());
+    }
+      
+    EvalBind(Dst, S, S, N, state,
+             loc::MemRegionVal(state->getRegion(VD, LC)), InitVal, true);
+  }
+}
+
+namespace {
+  // This class is used by VisitInitListExpr as an item in a worklist
+  // for processing the values contained in an InitListExpr.
+class InitListWLItem {
+public:
+  llvm::ImmutableList<SVal> Vals;
+  ExplodedNode* N;
+  InitListExpr::reverse_iterator Itr;
+
+  InitListWLItem(ExplodedNode* n, llvm::ImmutableList<SVal> vals,
+                 InitListExpr::reverse_iterator itr)
+  : Vals(vals), N(n), Itr(itr) {}
+};
+}
+
+
+void GRExprEngine::VisitInitListExpr(InitListExpr* E, ExplodedNode* Pred,
+                                     ExplodedNodeSet& Dst) {
+
+  const GRState* state = GetState(Pred);
+  QualType T = getContext().getCanonicalType(E->getType());
+  unsigned NumInitElements = E->getNumInits();
+
+  if (T->isArrayType() || T->isStructureType() ||
+      T->isUnionType() || T->isVectorType()) {
+
+    llvm::ImmutableList<SVal> StartVals = getBasicVals().getEmptySValList();
+
+    // Handle base case where the initializer has no elements.
+    // e.g: static int* myArray[] = {};
+    if (NumInitElements == 0) {
+      SVal V = ValMgr.makeCompoundVal(T, StartVals);
+      MakeNode(Dst, E, Pred, state->BindExpr(E, V));
+      return;
+    }
+
+    // Create a worklist to process the initializers.
+    llvm::SmallVector<InitListWLItem, 10> WorkList;
+    WorkList.reserve(NumInitElements);
+    WorkList.push_back(InitListWLItem(Pred, StartVals, E->rbegin()));
+    InitListExpr::reverse_iterator ItrEnd = E->rend();
+    assert(!(E->rbegin() == E->rend()));
+
+    // Process the worklist until it is empty.
+    while (!WorkList.empty()) {
+      InitListWLItem X = WorkList.back();
+      WorkList.pop_back();
+
+      ExplodedNodeSet Tmp;
+      Visit(*X.Itr, X.N, Tmp);
+
+      InitListExpr::reverse_iterator NewItr = X.Itr + 1;
+
+      for (ExplodedNodeSet::iterator NI=Tmp.begin(),NE=Tmp.end();NI!=NE;++NI) {
+        // Get the last initializer value.
+        state = GetState(*NI);
+        SVal InitV = state->getSVal(cast<Expr>(*X.Itr));
+
+        // Construct the new list of values by prepending the new value to
+        // the already constructed list.
+        llvm::ImmutableList<SVal> NewVals =
+          getBasicVals().consVals(InitV, X.Vals);
+
+        if (NewItr == ItrEnd) {
+          // Now we have a list holding all init values. Make CompoundValData.
+          SVal V = ValMgr.makeCompoundVal(T, NewVals);
+
+          // Make final state and node.
+          MakeNode(Dst, E, *NI, state->BindExpr(E, V));
+        }
+        else {
+          // Still some initializer values to go.  Push them onto the worklist.
+          WorkList.push_back(InitListWLItem(*NI, NewVals, NewItr));
+        }
+      }
+    }
+
+    return;
+  }
+
+  if (Loc::IsLocType(T) || T->isIntegerType()) {
+    assert (E->getNumInits() == 1);
+    ExplodedNodeSet Tmp;
+    Expr* Init = E->getInit(0);
+    Visit(Init, Pred, Tmp);
+    for (ExplodedNodeSet::iterator I=Tmp.begin(), EI=Tmp.end(); I != EI; ++I) {
+      state = GetState(*I);
+      MakeNode(Dst, E, *I, state->BindExpr(E, state->getSVal(Init)));
+    }
+    return;
+  }
+
+  assert(0 && "unprocessed InitListExpr type");
+}
+
+/// VisitSizeOfAlignOfExpr - Transfer function for sizeof(type).
+void GRExprEngine::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr* Ex,
+                                          ExplodedNode* Pred,
+                                          ExplodedNodeSet& Dst) {
+  QualType T = Ex->getTypeOfArgument();
+  CharUnits amt;
+
+  if (Ex->isSizeOf()) {
+    if (T == getContext().VoidTy) {
+      // sizeof(void) == 1 byte.
+      amt = CharUnits::One();
+    }
+    else if (!T.getTypePtr()->isConstantSizeType()) {
+      // FIXME: Add support for VLAs.
+      Dst.Add(Pred);
+      return;
+    }
+    else if (T->isObjCInterfaceType()) {
+      // Some code tries to take the sizeof an ObjCInterfaceType, relying that
+      // the compiler has laid out its representation.  Just report Unknown
+      // for these.
+      Dst.Add(Pred);
+      return;
+    }
+    else {
+      // All other cases.
+      amt = getContext().getTypeSizeInChars(T);
+    }
+  }
+  else  // Get alignment of the type.
+    amt = getContext().getTypeAlignInChars(T);
+
+  MakeNode(Dst, Ex, Pred,
+           GetState(Pred)->BindExpr(Ex, 
+              ValMgr.makeIntVal(amt.getQuantity(), Ex->getType())));
+}
+
+
+void GRExprEngine::VisitUnaryOperator(UnaryOperator* U, ExplodedNode* Pred,
+                                      ExplodedNodeSet& Dst, bool asLValue) {
+
+  switch (U->getOpcode()) {
+
+    default:
+      break;
+
+    case UnaryOperator::Deref: {
+
+      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      ExplodedNodeSet Tmp;
+      Visit(Ex, Pred, Tmp);
+
+      for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+
+        const GRState* state = GetState(*I);
+        SVal location = state->getSVal(Ex);
+
+        if (asLValue)
+          MakeNode(Dst, U, *I, state->BindExpr(U, location),
+                   ProgramPoint::PostLValueKind);
+        else
+          EvalLoad(Dst, U, *I, state, location);
+      }
+
+      return;
+    }
+
+    case UnaryOperator::Real: {
+
+      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      ExplodedNodeSet Tmp;
+      Visit(Ex, Pred, Tmp);
+
+      for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+
+        // FIXME: We don't have complex SValues yet.
+        if (Ex->getType()->isAnyComplexType()) {
+          // Just report "Unknown."
+          Dst.Add(*I);
+          continue;
+        }
+
+        // For all other types, UnaryOperator::Real is an identity operation.
+        assert (U->getType() == Ex->getType());
+        const GRState* state = GetState(*I);
+        MakeNode(Dst, U, *I, state->BindExpr(U, state->getSVal(Ex)));
+      }
+
+      return;
+    }
+
+    case UnaryOperator::Imag: {
+
+      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      ExplodedNodeSet Tmp;
+      Visit(Ex, Pred, Tmp);
+
+      for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+        // FIXME: We don't have complex SValues yet.
+        if (Ex->getType()->isAnyComplexType()) {
+          // Just report "Unknown."
+          Dst.Add(*I);
+          continue;
+        }
+
+        // For all other types, UnaryOperator::Float returns 0.
+        assert (Ex->getType()->isIntegerType());
+        const GRState* state = GetState(*I);
+        SVal X = ValMgr.makeZeroVal(Ex->getType());
+        MakeNode(Dst, U, *I, state->BindExpr(U, X));
+      }
+
+      return;
+    }
+
+    case UnaryOperator::OffsetOf: {
+      Expr::EvalResult Res;
+      if (U->Evaluate(Res, getContext()) && Res.Val.isInt()) {
+        const APSInt &IV = Res.Val.getInt();
+        assert(IV.getBitWidth() == getContext().getTypeSize(U->getType()));
+        assert(U->getType()->isIntegerType());
+        assert(IV.isSigned() == U->getType()->isSignedIntegerType());
+        SVal X = ValMgr.makeIntVal(IV);      
+        MakeNode(Dst, U, Pred, GetState(Pred)->BindExpr(U, X));
+        return;
+      }
+      // FIXME: Handle the case where __builtin_offsetof is not a constant.
+      Dst.Add(Pred);
+      return;
+    }
+
+    case UnaryOperator::Plus: assert (!asLValue);  // FALL-THROUGH.
+    case UnaryOperator::Extension: {
+
+      // Unary "+" is a no-op, similar to a parentheses.  We still have places
+      // where it may be a block-level expression, so we need to
+      // generate an extra node that just propagates the value of the
+      // subexpression.
+
+      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      ExplodedNodeSet Tmp;
+      Visit(Ex, Pred, Tmp);
+
+      for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+        const GRState* state = GetState(*I);
+        MakeNode(Dst, U, *I, state->BindExpr(U, state->getSVal(Ex)));
+      }
+
+      return;
+    }
+
+    case UnaryOperator::AddrOf: {
+
+      assert(!asLValue);
+      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      ExplodedNodeSet Tmp;
+      VisitLValue(Ex, Pred, Tmp);
+
+      for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+        const GRState* state = GetState(*I);
+        SVal V = state->getSVal(Ex);
+        state = state->BindExpr(U, V);
+        MakeNode(Dst, U, *I, state);
+      }
+
+      return;
+    }
+
+    case UnaryOperator::LNot:
+    case UnaryOperator::Minus:
+    case UnaryOperator::Not: {
+
+      assert (!asLValue);
+      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      ExplodedNodeSet Tmp;
+      Visit(Ex, Pred, Tmp);
+
+      for (ExplodedNodeSet::iterator I=Tmp.begin(), E=Tmp.end(); I!=E; ++I) {
+        const GRState* state = GetState(*I);
+
+        // Get the value of the subexpression.
+        SVal V = state->getSVal(Ex);
+
+        if (V.isUnknownOrUndef()) {
+          MakeNode(Dst, U, *I, state->BindExpr(U, V));
+          continue;
+        }
+
+//        QualType DstT = getContext().getCanonicalType(U->getType());
+//        QualType SrcT = getContext().getCanonicalType(Ex->getType());
+//
+//        if (DstT != SrcT) // Perform promotions.
+//          V = EvalCast(V, DstT);
+//
+//        if (V.isUnknownOrUndef()) {
+//          MakeNode(Dst, U, *I, BindExpr(St, U, V));
+//          continue;
+//        }
+
+        switch (U->getOpcode()) {
+          default:
+            assert(false && "Invalid Opcode.");
+            break;
+
+          case UnaryOperator::Not:
+            // FIXME: Do we need to handle promotions?
+            state = state->BindExpr(U, EvalComplement(cast<NonLoc>(V)));
+            break;
+
+          case UnaryOperator::Minus:
+            // FIXME: Do we need to handle promotions?
+            state = state->BindExpr(U, EvalMinus(cast<NonLoc>(V)));
+            break;
+
+          case UnaryOperator::LNot:
+
+            // C99 6.5.3.3: "The expression !E is equivalent to (0==E)."
+            //
+            //  Note: technically we do "E == 0", but this is the same in the
+            //    transfer functions as "0 == E".
+            SVal Result;
+
+            if (isa<Loc>(V)) {
+              Loc X = ValMgr.makeNull();
+              Result = EvalBinOp(state, BinaryOperator::EQ, cast<Loc>(V), X,
+                                 U->getType());
+            }
+            else {
+              nonloc::ConcreteInt X(getBasicVals().getValue(0, Ex->getType()));
+              Result = EvalBinOp(state, BinaryOperator::EQ, cast<NonLoc>(V), X,
+                                 U->getType());
+            }
+
+            state = state->BindExpr(U, Result);
+
+            break;
+        }
+
+        MakeNode(Dst, U, *I, state);
+      }
+
+      return;
+    }
+  }
+
+  // Handle ++ and -- (both pre- and post-increment).
+
+  assert (U->isIncrementDecrementOp());
+  ExplodedNodeSet Tmp;
+  Expr* Ex = U->getSubExpr()->IgnoreParens();
+  VisitLValue(Ex, Pred, Tmp);
+
+  for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I!=E; ++I) {
+
+    const GRState* state = GetState(*I);
+    SVal V1 = state->getSVal(Ex);
+
+    // Perform a load.
+    ExplodedNodeSet Tmp2;
+    EvalLoad(Tmp2, Ex, *I, state, V1);
+
+    for (ExplodedNodeSet::iterator I2=Tmp2.begin(), E2=Tmp2.end();I2!=E2;++I2) {
+
+      state = GetState(*I2);
+      SVal V2_untested = state->getSVal(Ex);
+
+      // Propagate unknown and undefined values.
+      if (V2_untested.isUnknownOrUndef()) {
+        MakeNode(Dst, U, *I2, state->BindExpr(U, V2_untested));
+        continue;
+      }      
+      DefinedSVal V2 = cast<DefinedSVal>(V2_untested);
+
+      // Handle all other values.
+      BinaryOperator::Opcode Op = U->isIncrementOp() ? BinaryOperator::Add
+                                                     : BinaryOperator::Sub;
+
+      // If the UnaryOperator has non-location type, use its type to create the
+      // constant value. If the UnaryOperator has location type, create the
+      // constant with int type and pointer width.
+      SVal RHS;
+
+      if (U->getType()->isAnyPointerType())
+        RHS = ValMgr.makeIntValWithPtrWidth(1, false);
+      else
+        RHS = ValMgr.makeIntVal(1, U->getType());
+
+      SVal Result = EvalBinOp(state, Op, V2, RHS, U->getType());
+
+      // Conjure a new symbol if necessary to recover precision.
+      if (Result.isUnknown() || !getConstraintManager().canReasonAbout(Result)){
+        DefinedOrUnknownSVal SymVal =
+          ValMgr.getConjuredSymbolVal(NULL, Ex,
+                                      Builder->getCurrentBlockCount());
+        Result = SymVal;
+
+        // If the value is a location, ++/-- should always preserve
+        // non-nullness.  Check if the original value was non-null, and if so
+        // propagate that constraint.
+        if (Loc::IsLocType(U->getType())) {
+          DefinedOrUnknownSVal Constraint =
+            SVator.EvalEQ(state, V2, ValMgr.makeZeroVal(U->getType()));
+
+          if (!state->Assume(Constraint, true)) {
+            // It isn't feasible for the original value to be null.
+            // Propagate this constraint.
+            Constraint = SVator.EvalEQ(state, SymVal,
+                                       ValMgr.makeZeroVal(U->getType()));
+
+
+            state = state->Assume(Constraint, false);
+            assert(state);
+          }
+        }
+      }
+
+      state = state->BindExpr(U, U->isPostfix() ? V2 : Result);
+
+      // Perform the store.
+      EvalStore(Dst, NULL, U, *I2, state, V1, Result);
+    }
+  }
+}
+
+
+void GRExprEngine::VisitCXXThisExpr(CXXThisExpr *TE, ExplodedNode *Pred, 
+                                    ExplodedNodeSet & Dst) {
+  // Get the this object region from StoreManager.
+  const MemRegion *R =
+    ValMgr.getRegionManager().getCXXThisRegion(TE->getType(),
+                                               Pred->getLocationContext());
+  
+  const GRState *state = GetState(Pred);
+  SVal V = state->getSVal(loc::MemRegionVal(R));
+  MakeNode(Dst, TE, Pred, state->BindExpr(TE, V));
+}
+
+void GRExprEngine::VisitAsmStmt(AsmStmt* A, ExplodedNode* Pred, 
+                                ExplodedNodeSet& Dst) {
+  VisitAsmStmtHelperOutputs(A, A->begin_outputs(), A->end_outputs(), Pred, Dst);
+}
+
+void GRExprEngine::VisitAsmStmtHelperOutputs(AsmStmt* A,
+                                             AsmStmt::outputs_iterator I,
+                                             AsmStmt::outputs_iterator E,
+                                     ExplodedNode* Pred, ExplodedNodeSet& Dst) {
+  if (I == E) {
+    VisitAsmStmtHelperInputs(A, A->begin_inputs(), A->end_inputs(), Pred, Dst);
+    return;
+  }
+
+  ExplodedNodeSet Tmp;
+  VisitLValue(*I, Pred, Tmp);
+
+  ++I;
+
+  for (ExplodedNodeSet::iterator NI = Tmp.begin(), NE = Tmp.end();NI != NE;++NI)
+    VisitAsmStmtHelperOutputs(A, I, E, *NI, Dst);
+}
+
+void GRExprEngine::VisitAsmStmtHelperInputs(AsmStmt* A,
+                                            AsmStmt::inputs_iterator I,
+                                            AsmStmt::inputs_iterator E,
+                                            ExplodedNode* Pred, 
+                                            ExplodedNodeSet& Dst) {
+  if (I == E) {
+
+    // We have processed both the inputs and the outputs.  All of the outputs
+    // should evaluate to Locs.  Nuke all of their values.
+
+    // FIXME: Some day in the future it would be nice to allow a "plug-in"
+    // which interprets the inline asm and stores proper results in the
+    // outputs.
+
+    const GRState* state = GetState(Pred);
+
+    for (AsmStmt::outputs_iterator OI = A->begin_outputs(),
+                                   OE = A->end_outputs(); OI != OE; ++OI) {
+
+      SVal X = state->getSVal(*OI);
+      assert (!isa<NonLoc>(X));  // Should be an Lval, or unknown, undef.
+
+      if (isa<Loc>(X))
+        state = state->bindLoc(cast<Loc>(X), UnknownVal());
+    }
+
+    MakeNode(Dst, A, Pred, state);
+    return;
+  }
+
+  ExplodedNodeSet Tmp;
+  Visit(*I, Pred, Tmp);
+
+  ++I;
+
+  for (ExplodedNodeSet::iterator NI = Tmp.begin(), NE = Tmp.end(); NI!=NE; ++NI)
+    VisitAsmStmtHelperInputs(A, I, E, *NI, Dst);
+}
+
+void GRExprEngine::VisitReturnStmt(ReturnStmt *RS, ExplodedNode *Pred,
+                                   ExplodedNodeSet &Dst) {
+  
+  ExplodedNodeSet Src;
+  if (Expr *RetE = RS->getRetValue()) {
+    Visit(RetE, Pred, Src);
+  }
+  else {
+    Src.Add(Pred);
+  }
+  
+  ExplodedNodeSet CheckedSet;
+  CheckerVisit(RS, CheckedSet, Src, true);
+  
+  for (ExplodedNodeSet::iterator I = CheckedSet.begin(), E = CheckedSet.end();
+       I != E; ++I) {
+
+    assert(Builder && "GRStmtNodeBuilder must be defined.");
+    
+    Pred = *I;
+    unsigned size = Dst.size();
+    
+    SaveAndRestore<bool> OldSink(Builder->BuildSinks);
+    SaveOr OldHasGen(Builder->HasGeneratedNode);
+    
+    getTF().EvalReturn(Dst, *this, *Builder, RS, Pred);
+    
+    // Handle the case where no nodes where generated.    
+    if (!Builder->BuildSinks && Dst.size() == size && 
+        !Builder->HasGeneratedNode)
+      MakeNode(Dst, RS, Pred, GetState(Pred));
+  }
+}
+
+//===----------------------------------------------------------------------===//
+// Transfer functions: Binary operators.
+//===----------------------------------------------------------------------===//
+
+void GRExprEngine::VisitBinaryOperator(BinaryOperator* B,
+                                       ExplodedNode* Pred,
+                                       ExplodedNodeSet& Dst, bool asLValue) {
+
+  ExplodedNodeSet Tmp1;
+  Expr* LHS = B->getLHS()->IgnoreParens();
+  Expr* RHS = B->getRHS()->IgnoreParens();
+
+  // FIXME: Add proper support for ObjCImplicitSetterGetterRefExpr.
+  if (isa<ObjCImplicitSetterGetterRefExpr>(LHS)) {
+    Visit(RHS, Pred, Dst);
+    return;
+  }
+
+  if (B->isAssignmentOp())
+    VisitLValue(LHS, Pred, Tmp1);
+  else
+    Visit(LHS, Pred, Tmp1);
+
+  ExplodedNodeSet Tmp3;
+
+  for (ExplodedNodeSet::iterator I1=Tmp1.begin(), E1=Tmp1.end(); I1!=E1; ++I1) {
+    SVal LeftV = (*I1)->getState()->getSVal(LHS);
+    ExplodedNodeSet Tmp2;
+    Visit(RHS, *I1, Tmp2);
+
+    ExplodedNodeSet CheckedSet;
+    CheckerVisit(B, CheckedSet, Tmp2, true);
+
+    // With both the LHS and RHS evaluated, process the operation itself.
+
+    for (ExplodedNodeSet::iterator I2=CheckedSet.begin(), E2=CheckedSet.end();
+         I2 != E2; ++I2) {
+
+      const GRState *state = GetState(*I2);
+      const GRState *OldSt = state;
+      SVal RightV = state->getSVal(RHS);
+
+      BinaryOperator::Opcode Op = B->getOpcode();
+
+      if (Op == BinaryOperator::Assign) {
+        // EXPERIMENTAL: "Conjured" symbols.
+        // FIXME: Handle structs.
+        QualType T = RHS->getType();
+        
+        if ((RightV.isUnknown()||!getConstraintManager().canReasonAbout(RightV))
+            && (Loc::IsLocType(T) || (T->isScalarType()&&T->isIntegerType()))) {
+          unsigned Count = Builder->getCurrentBlockCount();
+          RightV = ValMgr.getConjuredSymbolVal(NULL, B->getRHS(), Count);
+        }
+
+        SVal ExprVal = asLValue ? LeftV : RightV;
+
+        // Simulate the effects of a "store":  bind the value of the RHS
+        // to the L-Value represented by the LHS.
+        EvalStore(Tmp3, B, LHS, *I2, state->BindExpr(B, ExprVal), LeftV,RightV);
+        continue;
+      }
+      
+      if (!B->isAssignmentOp()) {
+        // Process non-assignments except commas or short-circuited
+        // logical expressions (LAnd and LOr).
+        SVal Result = EvalBinOp(state, Op, LeftV, RightV, B->getType());
+        
+        if (Result.isUnknown()) {
+          if (OldSt != state) {
+            // Generate a new node if we have already created a new state.
+            MakeNode(Tmp3, B, *I2, state);
+          }
+          else
+            Tmp3.Add(*I2);
+          
+          continue;
+        }
+        
+        state = state->BindExpr(B, Result);
+        
+        MakeNode(Tmp3, B, *I2, state);
+        continue;
+      }
+
+      assert (B->isCompoundAssignmentOp());
+
+      switch (Op) {
+        default:
+          assert(0 && "Invalid opcode for compound assignment.");
+        case BinaryOperator::MulAssign: Op = BinaryOperator::Mul; break;
+        case BinaryOperator::DivAssign: Op = BinaryOperator::Div; break;
+        case BinaryOperator::RemAssign: Op = BinaryOperator::Rem; break;
+        case BinaryOperator::AddAssign: Op = BinaryOperator::Add; break;
+        case BinaryOperator::SubAssign: Op = BinaryOperator::Sub; break;
+        case BinaryOperator::ShlAssign: Op = BinaryOperator::Shl; break;
+        case BinaryOperator::ShrAssign: Op = BinaryOperator::Shr; break;
+        case BinaryOperator::AndAssign: Op = BinaryOperator::And; break;
+        case BinaryOperator::XorAssign: Op = BinaryOperator::Xor; break;
+        case BinaryOperator::OrAssign:  Op = BinaryOperator::Or;  break;
+      }
+
+      // Perform a load (the LHS).  This performs the checks for
+      // null dereferences, and so on.
+      ExplodedNodeSet Tmp4;
+      SVal location = state->getSVal(LHS);
+      EvalLoad(Tmp4, LHS, *I2, state, location);
+
+      for (ExplodedNodeSet::iterator I4=Tmp4.begin(), E4=Tmp4.end(); I4!=E4;
+           ++I4) {
+        state = GetState(*I4);
+        SVal V = state->getSVal(LHS);
+
+        // Get the computation type.
+        QualType CTy =
+          cast<CompoundAssignOperator>(B)->getComputationResultType();
+        CTy = getContext().getCanonicalType(CTy);
+
+        QualType CLHSTy =
+          cast<CompoundAssignOperator>(B)->getComputationLHSType();
+        CLHSTy = getContext().getCanonicalType(CLHSTy);
+
+        QualType LTy = getContext().getCanonicalType(LHS->getType());
+        QualType RTy = getContext().getCanonicalType(RHS->getType());
+
+        // Promote LHS.
+        V = SVator.EvalCast(V, CLHSTy, LTy);
+
+        // Compute the result of the operation.
+        SVal Result = SVator.EvalCast(EvalBinOp(state, Op, V, RightV, CTy),
+                                      B->getType(), CTy);
+
+        // EXPERIMENTAL: "Conjured" symbols.
+        // FIXME: Handle structs.
+
+        SVal LHSVal;
+
+        if ((Result.isUnknown() ||
+             !getConstraintManager().canReasonAbout(Result))
+            && (Loc::IsLocType(CTy)
+                || (CTy->isScalarType() && CTy->isIntegerType()))) {
+
+          unsigned Count = Builder->getCurrentBlockCount();
+
+          // The symbolic value is actually for the type of the left-hand side
+          // expression, not the computation type, as this is the value the
+          // LValue on the LHS will bind to.
+          LHSVal = ValMgr.getConjuredSymbolVal(NULL, B->getRHS(), LTy, Count);
+
+          // However, we need to convert the symbol to the computation type.
+          Result = SVator.EvalCast(LHSVal, CTy, LTy);
+        }
+        else {
+          // The left-hand side may bind to a different value then the
+          // computation type.
+          LHSVal = SVator.EvalCast(Result, LTy, CTy);
+        }
+
+        EvalStore(Tmp3, B, LHS, *I4, state->BindExpr(B, Result),
+                  location, LHSVal);
+      }
+    }
+  }
+
+  CheckerVisit(B, Dst, Tmp3, false);
+}
+
+void GRExprEngine::CreateCXXTemporaryObject(Expr *Ex, ExplodedNode *Pred, 
+                                            ExplodedNodeSet &Dst) {
+  ExplodedNodeSet Tmp;
+  Visit(Ex, Pred, Tmp);
+  for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I != E; ++I) {
+    const GRState *state = GetState(*I);
+    
+    // Bind the temporary object to the value of the expression. Then bind
+    // the expression to the location of the object.
+    SVal V = state->getSVal(Ex);
+
+    const MemRegion *R = 
+      ValMgr.getRegionManager().getCXXObjectRegion(Ex,
+                                                   Pred->getLocationContext());
+
+    state = state->bindLoc(loc::MemRegionVal(R), V);
+    MakeNode(Dst, Ex, Pred, state->BindExpr(Ex, loc::MemRegionVal(R)));
+  }  
+}
+
+//===----------------------------------------------------------------------===//
+// Checker registration/lookup.
+//===----------------------------------------------------------------------===//
+
+Checker *GRExprEngine::lookupChecker(void *tag) const {
+  CheckerMap::const_iterator I = CheckerM.find(tag);
+  return (I == CheckerM.end()) ? NULL : Checkers[I->second].second;
+}
+
+//===----------------------------------------------------------------------===//
+// Visualization.
+//===----------------------------------------------------------------------===//
+
+#ifndef NDEBUG
+static GRExprEngine* GraphPrintCheckerState;
+static SourceManager* GraphPrintSourceManager;
+
+namespace llvm {
+template<>
+struct DOTGraphTraits<ExplodedNode*> :
+  public DefaultDOTGraphTraits {
+
+  DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
+
+  // FIXME: Since we do not cache error nodes in GRExprEngine now, this does not
+  // work.
+  static std::string getNodeAttributes(const ExplodedNode* N, void*) {
+
+#if 0
+      // FIXME: Replace with a general scheme to tell if the node is
+      // an error node.
+    if (GraphPrintCheckerState->isImplicitNullDeref(N) ||
+        GraphPrintCheckerState->isExplicitNullDeref(N) ||
+        GraphPrintCheckerState->isUndefDeref(N) ||
+        GraphPrintCheckerState->isUndefStore(N) ||
+        GraphPrintCheckerState->isUndefControlFlow(N) ||
+        GraphPrintCheckerState->isUndefResult(N) ||
+        GraphPrintCheckerState->isBadCall(N) ||
+        GraphPrintCheckerState->isUndefArg(N))
+      return "color=\"red\",style=\"filled\"";
+
+    if (GraphPrintCheckerState->isNoReturnCall(N))
+      return "color=\"blue\",style=\"filled\"";
+#endif
+    return "";
+  }
+
+  static std::string getNodeLabel(const ExplodedNode* N, void*){
+
+    std::string sbuf;
+    llvm::raw_string_ostream Out(sbuf);
+
+    // Program Location.
+    ProgramPoint Loc = N->getLocation();
+
+    switch (Loc.getKind()) {
+      case ProgramPoint::BlockEntranceKind:
+        Out << "Block Entrance: B"
+            << cast<BlockEntrance>(Loc).getBlock()->getBlockID();
+        break;
+
+      case ProgramPoint::BlockExitKind:
+        assert (false);
+        break;
+
+      default: {
+        if (StmtPoint *L = dyn_cast<StmtPoint>(&Loc)) {
+          const Stmt* S = L->getStmt();
+          SourceLocation SLoc = S->getLocStart();
+
+          Out << S->getStmtClassName() << ' ' << (void*) S << ' ';
+          LangOptions LO; // FIXME.
+          S->printPretty(Out, 0, PrintingPolicy(LO));
+
+          if (SLoc.isFileID()) {
+            Out << "\\lline="
+              << GraphPrintSourceManager->getInstantiationLineNumber(SLoc)
+              << " col="
+              << GraphPrintSourceManager->getInstantiationColumnNumber(SLoc)
+              << "\\l";
+          }
+
+          if (isa<PreStmt>(Loc))
+            Out << "\\lPreStmt\\l;";
+          else if (isa<PostLoad>(Loc))
+            Out << "\\lPostLoad\\l;";
+          else if (isa<PostStore>(Loc))
+            Out << "\\lPostStore\\l";
+          else if (isa<PostLValue>(Loc))
+            Out << "\\lPostLValue\\l";
+
+#if 0
+            // FIXME: Replace with a general scheme to determine
+            // the name of the check.
+          if (GraphPrintCheckerState->isImplicitNullDeref(N))
+            Out << "\\|Implicit-Null Dereference.\\l";
+          else if (GraphPrintCheckerState->isExplicitNullDeref(N))
+            Out << "\\|Explicit-Null Dereference.\\l";
+          else if (GraphPrintCheckerState->isUndefDeref(N))
+            Out << "\\|Dereference of undefialied value.\\l";
+          else if (GraphPrintCheckerState->isUndefStore(N))
+            Out << "\\|Store to Undefined Loc.";
+          else if (GraphPrintCheckerState->isUndefResult(N))
+            Out << "\\|Result of operation is undefined.";
+          else if (GraphPrintCheckerState->isNoReturnCall(N))
+            Out << "\\|Call to function marked \"noreturn\".";
+          else if (GraphPrintCheckerState->isBadCall(N))
+            Out << "\\|Call to NULL/Undefined.";
+          else if (GraphPrintCheckerState->isUndefArg(N))
+            Out << "\\|Argument in call is undefined";
+#endif
+
+          break;
+        }
+
+        const BlockEdge& E = cast<BlockEdge>(Loc);
+        Out << "Edge: (B" << E.getSrc()->getBlockID() << ", B"
+            << E.getDst()->getBlockID()  << ')';
+
+        if (Stmt* T = E.getSrc()->getTerminator()) {
+
+          SourceLocation SLoc = T->getLocStart();
+
+          Out << "\\|Terminator: ";
+          LangOptions LO; // FIXME.
+          E.getSrc()->printTerminator(Out, LO);
+
+          if (SLoc.isFileID()) {
+            Out << "\\lline="
+              << GraphPrintSourceManager->getInstantiationLineNumber(SLoc)
+              << " col="
+              << GraphPrintSourceManager->getInstantiationColumnNumber(SLoc);
+          }
+
+          if (isa<SwitchStmt>(T)) {
+            Stmt* Label = E.getDst()->getLabel();
+
+            if (Label) {
+              if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) {
+                Out << "\\lcase ";
+                LangOptions LO; // FIXME.
+                C->getLHS()->printPretty(Out, 0, PrintingPolicy(LO));
+
+                if (Stmt* RHS = C->getRHS()) {
+                  Out << " .. ";
+                  RHS->printPretty(Out, 0, PrintingPolicy(LO));
+                }
+
+                Out << ":";
+              }
+              else {
+                assert (isa<DefaultStmt>(Label));
+                Out << "\\ldefault:";
+              }
+            }
+            else
+              Out << "\\l(implicit) default:";
+          }
+          else if (isa<IndirectGotoStmt>(T)) {
+            // FIXME
+          }
+          else {
+            Out << "\\lCondition: ";
+            if (*E.getSrc()->succ_begin() == E.getDst())
+              Out << "true";
+            else
+              Out << "false";
+          }
+
+          Out << "\\l";
+        }
+
+#if 0
+          // FIXME: Replace with a general scheme to determine
+          // the name of the check.
+        if (GraphPrintCheckerState->isUndefControlFlow(N)) {
+          Out << "\\|Control-flow based on\\lUndefined value.\\l";
+        }
+#endif
+      }
+    }
+
+    Out << "\\|StateID: " << (void*) N->getState() << "\\|";
+
+    const GRState *state = N->getState();
+    state->printDOT(Out);
+
+    Out << "\\l";
+    return Out.str();
+  }
+};
+} // end llvm namespace
+#endif
+
+#ifndef NDEBUG
+template <typename ITERATOR>
+ExplodedNode* GetGraphNode(ITERATOR I) { return *I; }
+
+template <> ExplodedNode*
+GetGraphNode<llvm::DenseMap<ExplodedNode*, Expr*>::iterator>
+  (llvm::DenseMap<ExplodedNode*, Expr*>::iterator I) {
+  return I->first;
+}
+#endif
+
+void GRExprEngine::ViewGraph(bool trim) {
+#ifndef NDEBUG
+  if (trim) {
+    std::vector<ExplodedNode*> Src;
+
+    // Flush any outstanding reports to make sure we cover all the nodes.
+    // This does not cause them to get displayed.
+    for (BugReporter::iterator I=BR.begin(), E=BR.end(); I!=E; ++I)
+      const_cast<BugType*>(*I)->FlushReports(BR);
+
+    // Iterate through the reports and get their nodes.
+    for (BugReporter::iterator I=BR.begin(), E=BR.end(); I!=E; ++I) {
+      for (BugType::const_iterator I2=(*I)->begin(), E2=(*I)->end();
+           I2!=E2; ++I2) {
+        const BugReportEquivClass& EQ = *I2;
+        const BugReport &R = **EQ.begin();
+        ExplodedNode *N = const_cast<ExplodedNode*>(R.getEndNode());
+        if (N) Src.push_back(N);
+      }
+    }
+
+    ViewGraph(&Src[0], &Src[0]+Src.size());
+  }
+  else {
+    GraphPrintCheckerState = this;
+    GraphPrintSourceManager = &getContext().getSourceManager();
+
+    llvm::ViewGraph(*G.roots_begin(), "GRExprEngine");
+
+    GraphPrintCheckerState = NULL;
+    GraphPrintSourceManager = NULL;
+  }
+#endif
+}
+
+void GRExprEngine::ViewGraph(ExplodedNode** Beg, ExplodedNode** End) {
+#ifndef NDEBUG
+  GraphPrintCheckerState = this;
+  GraphPrintSourceManager = &getContext().getSourceManager();
+
+  std::auto_ptr<ExplodedGraph> TrimmedG(G.Trim(Beg, End).first);
+
+  if (!TrimmedG.get())
+    llvm::errs() << "warning: Trimmed ExplodedGraph is empty.\n";
+  else
+    llvm::ViewGraph(*TrimmedG->roots_begin(), "TrimmedGRExprEngine");
+
+  GraphPrintCheckerState = NULL;
+  GraphPrintSourceManager = NULL;
+#endif
+}