Constify all references to Stmt* and CFGBlock* in libChecker.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@108811 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Checker/BugReporter.cpp b/lib/Checker/BugReporter.cpp
index 0422d80..90ae459 100644
--- a/lib/Checker/BugReporter.cpp
+++ b/lib/Checker/BugReporter.cpp
@@ -541,9 +541,9 @@
     ProgramPoint P = N->getLocation();
 
     if (const BlockEdge* BE = dyn_cast<BlockEdge>(&P)) {
-      CFGBlock* Src = BE->getSrc();
-      CFGBlock* Dst = BE->getDst();
-      Stmt* T = Src->getTerminator();
+      const CFGBlock* Src = BE->getSrc();
+      const CFGBlock* Dst = BE->getDst();
+      const Stmt* T = Src->getTerminator();
 
       if (!T)
         continue;
@@ -577,7 +577,7 @@
           std::string sbuf;
           llvm::raw_string_ostream os(sbuf);
 
-          if (Stmt* S = Dst->getLabel()) {
+          if (const Stmt* S = Dst->getLabel()) {
             PathDiagnosticLocation End(S, SMgr);
 
             switch (S->getStmtClass()) {
@@ -593,17 +593,17 @@
 
               case Stmt::CaseStmtClass: {
                 os << "Control jumps to 'case ";
-                CaseStmt* Case = cast<CaseStmt>(S);
-                Expr* LHS = Case->getLHS()->IgnoreParenCasts();
+                const CaseStmt* Case = cast<CaseStmt>(S);
+                const Expr* LHS = Case->getLHS()->IgnoreParenCasts();
 
                 // Determine if it is an enum.
                 bool GetRawInt = true;
 
-                if (DeclRefExpr* DR = dyn_cast<DeclRefExpr>(LHS)) {
+                if (const DeclRefExpr* DR = dyn_cast<DeclRefExpr>(LHS)) {
                   // FIXME: Maybe this should be an assertion.  Are there cases
                   // were it is not an EnumConstantDecl?
-                  EnumConstantDecl* D =
-                  dyn_cast<EnumConstantDecl>(DR->getDecl());
+                  const EnumConstantDecl* D =
+                    dyn_cast<EnumConstantDecl>(DR->getDecl());
 
                   if (D) {
                     GetRawInt = false;
@@ -668,7 +668,7 @@
           if (!PDB.supportsLogicalOpControlFlow())
             break;
 
-          BinaryOperator *B = cast<BinaryOperator>(T);
+          const BinaryOperator *B = cast<BinaryOperator>(T);
           std::string sbuf;
           llvm::raw_string_ostream os(sbuf);
           os << "Left side of '";
diff --git a/lib/Checker/BugReporterVisitors.cpp b/lib/Checker/BugReporterVisitors.cpp
index 776e12b..0323fe6 100644
--- a/lib/Checker/BugReporterVisitors.cpp
+++ b/lib/Checker/BugReporterVisitors.cpp
@@ -209,7 +209,7 @@
     ProgramPoint P = N->getLocation();
 
     if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
-      CFGBlock *BSrc = BE->getSrc();
+      const CFGBlock *BSrc = BE->getSrc();
       S = BSrc->getTerminatorCondition();
     }
     else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) {
@@ -282,7 +282,7 @@
       ProgramPoint P = N->getLocation();
 
       if (BlockEdge *BE = dyn_cast<BlockEdge>(&P)) {
-        CFGBlock *BSrc = BE->getSrc();
+        const CFGBlock *BSrc = BE->getSrc();
         S = BSrc->getTerminatorCondition();
       }
       else if (PostStmt *PS = dyn_cast<PostStmt>(&P)) {
diff --git a/lib/Checker/CFRefCount.cpp b/lib/Checker/CFRefCount.cpp
index 4e7787e..0cc8905 100644
--- a/lib/Checker/CFRefCount.cpp
+++ b/lib/Checker/CFRefCount.cpp
@@ -92,11 +92,11 @@
 namespace {
 class GenericNodeBuilder {
   GRStmtNodeBuilder *SNB;
-  Stmt *S;
+  const Stmt *S;
   const void *tag;
   GREndPathNodeBuilder *ENB;
 public:
-  GenericNodeBuilder(GRStmtNodeBuilder &snb, Stmt *s,
+  GenericNodeBuilder(GRStmtNodeBuilder &snb, const Stmt *s,
                      const void *t)
   : SNB(&snb), S(s), tag(t), ENB(0) {}
 
@@ -1769,7 +1769,7 @@
 
   void ProcessNonLeakError(ExplodedNodeSet& Dst,
                            GRStmtNodeBuilder& Builder,
-                           Expr* NodeExpr, SourceRange ErrorRange,
+                           const Expr* NodeExpr, SourceRange ErrorRange,
                            ExplodedNode* Pred,
                            const GRState* St,
                            RefVal::Kind hasErr, SymbolRef Sym);
@@ -1812,31 +1812,31 @@
   void EvalSummary(ExplodedNodeSet& Dst,
                    GRExprEngine& Eng,
                    GRStmtNodeBuilder& Builder,
-                   Expr* Ex,
+                   const Expr* Ex,
                    InstanceReceiver Receiver,
                    const RetainSummary& Summ,
                    const MemRegion *Callee,
-                   ExprIterator arg_beg, ExprIterator arg_end,
+                   ConstExprIterator arg_beg, ConstExprIterator arg_end,
                    ExplodedNode* Pred, const GRState *state);
 
   virtual void EvalCall(ExplodedNodeSet& Dst,
                         GRExprEngine& Eng,
                         GRStmtNodeBuilder& Builder,
-                        CallExpr* CE, SVal L,
+                        const CallExpr* CE, SVal L,
                         ExplodedNode* Pred);
 
 
   virtual void EvalObjCMessageExpr(ExplodedNodeSet& Dst,
                                    GRExprEngine& Engine,
                                    GRStmtNodeBuilder& Builder,
-                                   ObjCMessageExpr* ME,
+                                   const ObjCMessageExpr* ME,
                                    ExplodedNode* Pred,
                                    const GRState *state);
 
   bool EvalObjCMessageExprAux(ExplodedNodeSet& Dst,
                               GRExprEngine& Engine,
                               GRStmtNodeBuilder& Builder,
-                              ObjCMessageExpr* ME,
+                              const ObjCMessageExpr* ME,
                               ExplodedNode* Pred);
 
   // Stores.
@@ -1863,7 +1863,7 @@
   virtual void EvalReturn(ExplodedNodeSet& Dst,
                           GRExprEngine& Engine,
                           GRStmtNodeBuilder& Builder,
-                          ReturnStmt* S,
+                          const ReturnStmt* S,
                           ExplodedNode* Pred);
 
   // Assumptions.
@@ -2607,11 +2607,12 @@
 void CFRefCount::EvalSummary(ExplodedNodeSet& Dst,
                              GRExprEngine& Eng,
                              GRStmtNodeBuilder& Builder,
-                             Expr* Ex,
+                             const Expr* Ex,
                              InstanceReceiver Receiver,
                              const RetainSummary& Summ,
                              const MemRegion *Callee,
-                             ExprIterator arg_beg, ExprIterator arg_end,
+                             ConstExprIterator arg_beg, 
+                             ConstExprIterator arg_end,
                              ExplodedNode* Pred, const GRState *state) {
 
   // Evaluate the effect of the arguments.
@@ -2622,7 +2623,7 @@
 
   llvm::SmallVector<const MemRegion*, 10> RegionsToInvalidate;
 
-  for (ExprIterator I = arg_beg; I != arg_end; ++I, ++idx) {
+  for (ConstExprIterator I = arg_beg; I != arg_end; ++I, ++idx) {
     SVal V = state->getSValAsScalarOrLoc(*I);
     SymbolRef Sym = V.getAsLocSymbol();
 
@@ -2862,7 +2863,7 @@
 void CFRefCount::EvalCall(ExplodedNodeSet& Dst,
                           GRExprEngine& Eng,
                           GRStmtNodeBuilder& Builder,
-                          CallExpr* CE, SVal L,
+                          const CallExpr* CE, SVal L,
                           ExplodedNode* Pred) {
 
   RetainSummary *Summ = 0;
@@ -2887,7 +2888,7 @@
 void CFRefCount::EvalObjCMessageExpr(ExplodedNodeSet& Dst,
                                      GRExprEngine& Eng,
                                      GRStmtNodeBuilder& Builder,
-                                     ObjCMessageExpr* ME,
+                                     const ObjCMessageExpr* ME,
                                      ExplodedNode* Pred,
                                      const GRState *state) {
   RetainSummary *Summ =
@@ -2958,10 +2959,10 @@
 void CFRefCount::EvalReturn(ExplodedNodeSet& Dst,
                             GRExprEngine& Eng,
                             GRStmtNodeBuilder& Builder,
-                            ReturnStmt* S,
+                            const ReturnStmt* S,
                             ExplodedNode* Pred) {
 
-  Expr* RetE = S->getRetValue();
+  const Expr* RetE = S->getRetValue();
   if (!RetE)
     return;
 
@@ -3406,7 +3407,7 @@
                                  ExplodedNode* Pred,
                                  const GRState* state,
                                  SymbolReaper& SymReaper) {
-  Stmt *S = Builder.getStmt();
+  const Stmt *S = Builder.getStmt();
   RefBindings B = state->get<RefBindings>();
 
   // Update counts from autorelease pools
@@ -3456,7 +3457,8 @@
 
 void CFRefCount::ProcessNonLeakError(ExplodedNodeSet& Dst,
                                      GRStmtNodeBuilder& Builder,
-                                     Expr* NodeExpr, SourceRange ErrorRange,
+                                     const Expr* NodeExpr, 
+                                     SourceRange ErrorRange,
                                      ExplodedNode* Pred,
                                      const GRState* St,
                                      RefVal::Kind hasErr, SymbolRef Sym) {
diff --git a/lib/Checker/GRCXXExprEngine.cpp b/lib/Checker/GRCXXExprEngine.cpp
index 5c31331..d9cd3de 100644
--- a/lib/Checker/GRCXXExprEngine.cpp
+++ b/lib/Checker/GRCXXExprEngine.cpp
@@ -17,7 +17,7 @@
 
 using namespace clang;
 
-void GRExprEngine::EvalArguments(ExprIterator AI, ExprIterator AE,
+void GRExprEngine::EvalArguments(ConstExprIterator AI, ConstExprIterator AE,
                                  const FunctionProtoType *FnType, 
                                  ExplodedNode *Pred, ExplodedNodeSet &Dst) {
   llvm::SmallVector<CallExprWLItem, 20> WorkList;
@@ -55,7 +55,7 @@
   return ValMgr.getRegionManager().getCXXThisRegion(PT, SFC);
 }
 
-void GRExprEngine::CreateCXXTemporaryObject(Expr *Ex, ExplodedNode *Pred,
+void GRExprEngine::CreateCXXTemporaryObject(const Expr *Ex, ExplodedNode *Pred,
                                             ExplodedNodeSet &Dst) {
   ExplodedNodeSet Tmp;
   Visit(Ex, Pred, Tmp);
@@ -94,9 +94,7 @@
   // Evaluate other arguments.
   ExplodedNodeSet ArgsEvaluated;
   const FunctionProtoType *FnType = CD->getType()->getAs<FunctionProtoType>();
-  EvalArguments(const_cast<CXXConstructExpr*>(E)->arg_begin(),
-                const_cast<CXXConstructExpr*>(E)->arg_end(),
-                FnType, Pred, ArgsEvaluated);
+  EvalArguments(E->arg_begin(), E->arg_end(), FnType, Pred, ArgsEvaluated);
   // The callee stack frame context used to create the 'this' parameter region.
   const StackFrameContext *SFC = AMgr.getStackFrame(CD, 
                                                     Pred->getLocationContext(),
@@ -126,9 +124,7 @@
 
   // Evaluate explicit arguments with a worklist.
   ExplodedNodeSet ArgsEvaluated;
-  EvalArguments(const_cast<CXXMemberCallExpr*>(MCE)->arg_begin(),
-                const_cast<CXXMemberCallExpr*>(MCE)->arg_end(),
-                FnType, Pred, ArgsEvaluated);
+  EvalArguments(MCE->arg_begin(), MCE->arg_end(), FnType, Pred, ArgsEvaluated);
  
   // Evaluate the implicit object argument.
   ExplodedNodeSet AllArgsEvaluated;
@@ -169,7 +165,7 @@
   }
 }
 
-void GRExprEngine::VisitCXXNewExpr(CXXNewExpr *CNE, ExplodedNode *Pred,
+void GRExprEngine::VisitCXXNewExpr(const CXXNewExpr *CNE, ExplodedNode *Pred,
                                    ExplodedNodeSet &Dst) {
   if (CNE->isArray()) {
     // FIXME: allocating an array has not been handled.
@@ -177,7 +173,7 @@
   }
 
   unsigned Count = Builder->getCurrentBlockCount();
-  DefinedOrUnknownSVal SymVal = getValueManager().getConjuredSymbolVal(NULL,CNE, 
+  DefinedOrUnknownSVal SymVal = getValueManager().getConjuredSymbolVal(NULL,CNE,
                                                          CNE->getType(), Count);
   const MemRegion *NewReg = cast<loc::MemRegionVal>(SymVal).getRegion();
 
@@ -220,8 +216,8 @@
   }
 }
 
-void GRExprEngine::VisitCXXDeleteExpr(CXXDeleteExpr *CDE, ExplodedNode *Pred,
-                                      ExplodedNodeSet &Dst) {
+void GRExprEngine::VisitCXXDeleteExpr(const CXXDeleteExpr *CDE, 
+                                      ExplodedNode *Pred,ExplodedNodeSet &Dst) {
   // Should do more checking.
   ExplodedNodeSet ArgEvaluated;
   Visit(CDE->getArgument(), Pred, ArgEvaluated);
@@ -232,7 +228,7 @@
   }
 }
 
-void GRExprEngine::VisitCXXThisExpr(CXXThisExpr *TE, ExplodedNode *Pred,
+void GRExprEngine::VisitCXXThisExpr(const CXXThisExpr *TE, ExplodedNode *Pred,
                                     ExplodedNodeSet &Dst) {
   // Get the this object region from StoreManager.
   const MemRegion *R =
diff --git a/lib/Checker/GRCoreEngine.cpp b/lib/Checker/GRCoreEngine.cpp
index 87127f0..c8978fb 100644
--- a/lib/Checker/GRCoreEngine.cpp
+++ b/lib/Checker/GRCoreEngine.cpp
@@ -126,13 +126,14 @@
   SubEngine.ProcessStmt(E, Builder);
 }
 
-bool GRCoreEngine::ProcessBlockEntrance(CFGBlock* Blk, const ExplodedNode *Pred,
+bool GRCoreEngine::ProcessBlockEntrance(const CFGBlock* Blk, 
+                                        const ExplodedNode *Pred,
                                         GRBlockCounter BC) {
   return SubEngine.ProcessBlockEntrance(Blk, Pred, BC);
 }
 
-void GRCoreEngine::ProcessBranch(Stmt* Condition, Stmt* Terminator,
-                   GRBranchNodeBuilder& Builder) {
+void GRCoreEngine::ProcessBranch(const Stmt* Condition, const Stmt* Terminator,
+                                 GRBranchNodeBuilder& Builder) {
   SubEngine.ProcessBranch(Condition, Terminator, Builder);
 }
 
@@ -158,7 +159,7 @@
   if (G->num_roots() == 0) { // Initialize the analysis by constructing
     // the root if none exists.
 
-    CFGBlock* Entry = &(L->getCFG()->getEntry());
+    const CFGBlock* Entry = &(L->getCFG()->getEntry());
 
     assert (Entry->empty() &&
             "Entry block must be empty.");
@@ -167,7 +168,7 @@
             "Entry block must have 1 successor.");
 
     // Get the solitary successor.
-    CFGBlock* Succ = *(Entry->succ_begin());
+    const CFGBlock* Succ = *(Entry->succ_begin());
 
     // Construct an edge representing the
     // starting location in the function.
@@ -239,7 +240,7 @@
 
 void GRCoreEngine::HandleBlockEdge(const BlockEdge& L, ExplodedNode* Pred) {
 
-  CFGBlock* Blk = L.getDst();
+  const CFGBlock* Blk = L.getDst();
 
   // Check if we are entering the EXIT block.
   if (Blk == &(L.getLocationContext()->getCFG()->getExit())) {
@@ -284,9 +285,9 @@
     HandleBlockExit(L.getBlock(), Pred);
 }
 
-void GRCoreEngine::HandleBlockExit(CFGBlock * B, ExplodedNode* Pred) {
+void GRCoreEngine::HandleBlockExit(const CFGBlock * B, ExplodedNode* Pred) {
 
-  if (Stmt* Term = B->getTerminator()) {
+  if (const Stmt* Term = B->getTerminator()) {
     switch (Term->getStmtClass()) {
       default:
         assert(false && "Analysis for this terminator not implemented.");
@@ -372,8 +373,8 @@
                Pred->State, Pred);
 }
 
-void GRCoreEngine::HandleBranch(Stmt* Cond, Stmt* Term, CFGBlock * B,
-                                ExplodedNode* Pred) {
+void GRCoreEngine::HandleBranch(const Stmt* Cond, const Stmt* Term, 
+                                const CFGBlock * B, ExplodedNode* Pred) {
   assert (B->succ_size() == 2);
 
   GRBranchNodeBuilder Builder(B, *(B->succ_begin()), *(B->succ_begin()+1),
@@ -382,7 +383,7 @@
   ProcessBranch(Cond, Term, Builder);
 }
 
-void GRCoreEngine::HandlePostStmt(const PostStmt& L, CFGBlock* B,
+void GRCoreEngine::HandlePostStmt(const PostStmt& L, const CFGBlock* B,
                                   unsigned StmtIdx, ExplodedNode* Pred) {
 
   assert (!B->empty());
@@ -415,7 +416,7 @@
   if (IsNew) WList->Enqueue(Node);
 }
 
-GRStmtNodeBuilder::GRStmtNodeBuilder(CFGBlock* b, unsigned idx,
+GRStmtNodeBuilder::GRStmtNodeBuilder(const CFGBlock* b, unsigned idx,
                                      ExplodedNode* N, GRCoreEngine* e,
                                      GRStateManager &mgr)
   : Eng(*e), B(*b), Idx(idx), Pred(N), Mgr(mgr), Auditor(0),
@@ -438,7 +439,7 @@
   if (isa<CallEnter>(N->getLocation())) {
     // Still use the index of the CallExpr. It's needed to create the callee
     // StackFrameContext.
-    Eng.WList->Enqueue(N, B, Idx);
+    Eng.WList->Enqueue(N, &B, Idx);
     return;
   }
 
@@ -447,7 +448,7 @@
   if (Loc == N->getLocation()) {
     // Note: 'N' should be a fresh node because otherwise it shouldn't be
     // a member of Deferred.
-    Eng.WList->Enqueue(N, B, Idx+1);
+    Eng.WList->Enqueue(N, &B, Idx+1);
     return;
   }
 
@@ -456,7 +457,7 @@
   Succ->addPredecessor(N, *Eng.G);
 
   if (IsNew)
-    Eng.WList->Enqueue(Succ, B, Idx+1);
+    Eng.WList->Enqueue(Succ, &B, Idx+1);
 }
 
 ExplodedNode* GRStmtNodeBuilder::MakeNode(ExplodedNodeSet& Dst, const Stmt* S, 
@@ -727,6 +728,6 @@
   ExplodedNode *Node = Eng.G->getNode(Loc, state, &isNew);
   Node->addPredecessor(const_cast<ExplodedNode*>(Pred), *Eng.G);
   if (isNew)
-    Eng.WList->Enqueue(Node, *const_cast<CFGBlock*>(LocCtx->getCallSiteBlock()),
+    Eng.WList->Enqueue(Node, LocCtx->getCallSiteBlock(),
                        LocCtx->getIndex() + 1);
 }
diff --git a/lib/Checker/GRExprEngine.cpp b/lib/Checker/GRExprEngine.cpp
index d44b4fe..364f06d 100644
--- a/lib/Checker/GRExprEngine.cpp
+++ b/lib/Checker/GRExprEngine.cpp
@@ -169,7 +169,7 @@
 // Checker worklist routines.
 //===----------------------------------------------------------------------===//
 
-void GRExprEngine::CheckerVisit(Stmt *S, ExplodedNodeSet &Dst,
+void GRExprEngine::CheckerVisit(const Stmt *S, ExplodedNodeSet &Dst,
                                 ExplodedNodeSet &Src, bool isPrevisit) {
 
   // Determine if we already have a cached 'CheckersOrdered' vector
@@ -522,7 +522,7 @@
   }
 }
 
-void GRExprEngine::ProcessStmt(CFGElement CE, GRStmtNodeBuilder& builder) {
+void GRExprEngine::ProcessStmt(const CFGElement CE,GRStmtNodeBuilder& builder) {
   CurrentStmt = CE.getStmt();
   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
                                 CurrentStmt->getLocStart(),
@@ -626,7 +626,8 @@
   Builder = NULL;
 }
 
-void GRExprEngine::Visit(Stmt* S, ExplodedNode* Pred, ExplodedNodeSet& Dst) {
+void GRExprEngine::Visit(const Stmt* S, ExplodedNode* Pred, 
+                         ExplodedNodeSet& Dst) {
   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
                                 S->getLocStart(),
                                 "Error evaluating statement");
@@ -741,7 +742,7 @@
       break;
 
     case Stmt::BinaryOperatorClass: {
-      BinaryOperator* B = cast<BinaryOperator>(S);
+      const BinaryOperator* B = cast<BinaryOperator>(S);
 
       if (B->isLogicalOp()) {
         VisitLogicalExpr(B, Pred, Dst);
@@ -767,25 +768,25 @@
 
     case Stmt::CallExprClass:
     case Stmt::CXXOperatorCallExprClass: {
-      CallExpr* C = cast<CallExpr>(S);
+      const CallExpr* C = cast<CallExpr>(S);
       VisitCall(C, Pred, C->arg_begin(), C->arg_end(), Dst, false);
       break;
     }
 
     case Stmt::CXXMemberCallExprClass: {
-      CXXMemberCallExpr *MCE = cast<CXXMemberCallExpr>(S);
+      const CXXMemberCallExpr *MCE = cast<CXXMemberCallExpr>(S);
       VisitCXXMemberCallExpr(MCE, Pred, Dst);
       break;
     }
 
     case Stmt::CXXNewExprClass: {
-      CXXNewExpr *NE = cast<CXXNewExpr>(S);
+      const CXXNewExpr *NE = cast<CXXNewExpr>(S);
       VisitCXXNewExpr(NE, Pred, Dst);
       break;
     }
 
     case Stmt::CXXDeleteExprClass: {
-      CXXDeleteExpr *CDE = cast<CXXDeleteExpr>(S);
+      const CXXDeleteExpr *CDE = cast<CXXDeleteExpr>(S);
       VisitCXXDeleteExpr(CDE, Pred, Dst);
       break;
     }
@@ -793,7 +794,7 @@
       //        the CFG do not model them as explicit control-flow.
 
     case Stmt::ChooseExprClass: { // __builtin_choose_expr
-      ChooseExpr* C = cast<ChooseExpr>(S);
+      const ChooseExpr* C = cast<ChooseExpr>(S);
       VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst);
       break;
     }
@@ -807,7 +808,7 @@
       break;
 
     case Stmt::ConditionalOperatorClass: { // '?' operator
-      ConditionalOperator* C = cast<ConditionalOperator>(S);
+      const ConditionalOperator* C = cast<ConditionalOperator>(S);
       VisitGuardedExpr(C, C->getLHS(), C->getRHS(), Pred, Dst);
       break;
     }
@@ -837,7 +838,7 @@
     case Stmt::CXXReinterpretCastExprClass:
     case Stmt::CXXConstCastExprClass:
     case Stmt::CXXFunctionalCastExprClass: {
-      CastExpr* C = cast<CastExpr>(S);
+      const CastExpr* C = cast<CastExpr>(S);
       VisitCast(C, C->getSubExpr(), Pred, Dst, false);
       break;
     }
@@ -894,7 +895,7 @@
       break;
 
     case Stmt::StmtExprClass: {
-      StmtExpr* SE = cast<StmtExpr>(S);
+      const StmtExpr* SE = cast<StmtExpr>(S);
 
       if (SE->getSubStmt()->body_empty()) {
         // Empty statement expression.
@@ -925,7 +926,7 @@
       break;
 
     case Stmt::UnaryOperatorClass: {
-      UnaryOperator *U = cast<UnaryOperator>(S);
+      const UnaryOperator *U = cast<UnaryOperator>(S);
       if (AMgr.shouldEagerlyAssume()&&(U->getOpcode() == UnaryOperator::LNot)) {
         ExplodedNodeSet Tmp;
         VisitUnaryOperator(U, Pred, Tmp, false);
@@ -944,7 +945,7 @@
   }
 }
 
-void GRExprEngine::VisitLValue(Expr* Ex, ExplodedNode* Pred,
+void GRExprEngine::VisitLValue(const Expr* Ex, ExplodedNode* Pred,
                                ExplodedNodeSet& Dst) {
 
   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
@@ -985,7 +986,7 @@
 
     case Stmt::CallExprClass:
     case Stmt::CXXOperatorCallExprClass: {
-      CallExpr *C = cast<CallExpr>(Ex);
+      const CallExpr *C = cast<CallExpr>(Ex);
       assert(CalleeReturnsReferenceOrRecord(C));
       VisitCall(C, Pred, C->arg_begin(), C->arg_end(), Dst, true);
       break;
@@ -1001,7 +1002,7 @@
 
     case Stmt::ImplicitCastExprClass:
     case Stmt::CStyleCastExprClass: {
-      CastExpr *C = cast<CastExpr>(Ex);
+      const CastExpr *C = cast<CastExpr>(Ex);
       QualType T = Ex->getType();
       VisitCast(C, C->getSubExpr(), Pred, Dst, true);
       break;
@@ -1016,7 +1017,7 @@
       return;
 
     case Stmt::ObjCMessageExprClass: {
-      ObjCMessageExpr *ME = cast<ObjCMessageExpr>(Ex);
+      const ObjCMessageExpr *ME = cast<ObjCMessageExpr>(Ex);
       assert(ReceiverReturnsReferenceOrRecord(ME));
       VisitObjCMessageExpr(ME, Pred, Dst, true);
       return;
@@ -1082,7 +1083,8 @@
 // Block entrance.  (Update counters).
 //===----------------------------------------------------------------------===//
 
-bool GRExprEngine::ProcessBlockEntrance(CFGBlock* B, const ExplodedNode *Pred,
+bool GRExprEngine::ProcessBlockEntrance(const CFGBlock* B, 
+                                        const ExplodedNode *Pred,
                                         GRBlockCounter BC) {
   return BC.getNumVisited(Pred->getLocationContext()->getCurrentStackFrame(), 
                           B->getBlockID()) < AMgr.getMaxLoop();
@@ -1106,8 +1108,8 @@
 //===----------------------------------------------------------------------===//
 
 const GRState* GRExprEngine::MarkBranch(const GRState* state,
-                                           Stmt* Terminator,
-                                           bool branchTaken) {
+                                        const Stmt* Terminator,
+                                        bool branchTaken) {
 
   switch (Terminator->getStmtClass()) {
     default:
@@ -1115,7 +1117,7 @@
 
     case Stmt::BinaryOperatorClass: { // '&&' and '||'
 
-      BinaryOperator* B = cast<BinaryOperator>(Terminator);
+      const BinaryOperator* B = cast<BinaryOperator>(Terminator);
       BinaryOperator::Opcode Op = B->getOpcode();
 
       assert (Op == BinaryOperator::LAnd || Op == BinaryOperator::LOr);
@@ -1126,21 +1128,21 @@
       // 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();
+      const 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);
+      const ConditionalOperator* C = cast<ConditionalOperator>(Terminator);
 
       // For ?, if branchTaken == true then the value is either the LHS or
       // the condition itself. (GNU extension).
 
-      Expr* Ex;
+      const Expr* Ex;
 
       if (branchTaken)
         Ex = C->getLHS() ? C->getLHS() : C->getCond();
@@ -1152,9 +1154,9 @@
 
     case Stmt::ChooseExprClass: { // ?:
 
-      ChooseExpr* C = cast<ChooseExpr>(Terminator);
+      const ChooseExpr* C = cast<ChooseExpr>(Terminator);
 
-      Expr* Ex = branchTaken ? C->getLHS() : C->getRHS();
+      const Expr* Ex = branchTaken ? C->getLHS() : C->getRHS();
       return state->BindExpr(C, UndefinedVal(Ex));
     }
   }
@@ -1166,16 +1168,16 @@
 /// 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) {
+                                const Stmt* Condition, ASTContext& Ctx) {
 
-  Expr *Ex = dyn_cast<Expr>(Condition);
+  const Expr *Ex = dyn_cast<Expr>(Condition);
   if (!Ex)
     return UnknownVal();
 
   uint64_t bits = 0;
   bool bitsInit = false;
 
-  while (CastExpr *CE = dyn_cast<CastExpr>(Ex)) {
+  while (const CastExpr *CE = dyn_cast<CastExpr>(Ex)) {
     QualType T = CE->getType();
 
     if (!T->isIntegerType())
@@ -1199,7 +1201,7 @@
   return state->getSVal(Ex);
 }
 
-void GRExprEngine::ProcessBranch(Stmt* Condition, Stmt* Term,
+void GRExprEngine::ProcessBranch(const Stmt* Condition, const Stmt* Term,
                                  GRBranchNodeBuilder& builder) {
 
   // Check for NULL conditions; e.g. "for(;;)"
@@ -1286,7 +1288,7 @@
   typedef GRIndirectGotoNodeBuilder::iterator iterator;
 
   if (isa<loc::GotoLabel>(V)) {
-    LabelStmt* L = cast<loc::GotoLabel>(V).getLabel();
+    const LabelStmt* L = cast<loc::GotoLabel>(V).getLabel();
 
     for (iterator I=builder.begin(), E=builder.end(); I != E; ++I) {
       if (I.getLabel() == L) {
@@ -1315,7 +1317,8 @@
 }
 
 
-void GRExprEngine::VisitGuardedExpr(Expr* Ex, Expr* L, Expr* R,
+void GRExprEngine::VisitGuardedExpr(const Expr* Ex, const Expr* L, 
+                                    const Expr* R,
                                     ExplodedNode* Pred, ExplodedNodeSet& Dst) {
 
   assert(Ex == CurrentStmt &&
@@ -1326,7 +1329,7 @@
 
   assert (X.isUndef());
 
-  Expr *SE = (Expr*) cast<UndefinedVal>(X).getData();
+  const Expr *SE = (Expr*) cast<UndefinedVal>(X).getData();
   assert(SE);
   X = state->getSVal(SE);
 
@@ -1351,7 +1354,7 @@
 void GRExprEngine::ProcessSwitch(GRSwitchNodeBuilder& builder) {
   typedef GRSwitchNodeBuilder::iterator iterator;
   const GRState* state = builder.getState();
-  Expr* CondE = builder.getCondition();
+  const Expr* CondE = builder.getCondition();
   SVal  CondV_untested = state->getSVal(CondE);
 
   if (CondV_untested.isUndef()) {
@@ -1367,7 +1370,7 @@
   bool defaultIsFeasible = false;
 
   for (iterator I = builder.begin(), EI = builder.end(); I != EI; ++I) {
-    CaseStmt* Case = cast<CaseStmt>(I.getCase());
+    const CaseStmt* Case = cast<CaseStmt>(I.getCase());
 
     // Evaluate the LHS of the case value.
     Expr::EvalResult V1;
@@ -1383,7 +1386,7 @@
     // Get the RHS of the case, if it exists.
     Expr::EvalResult V2;
 
-    if (Expr* E = Case->getRHS()) {
+    if (const Expr* E = Case->getRHS()) {
       b = E->Evaluate(V2, getContext());
       assert(b && V2.Val.isInt() && !V2.HasSideEffects
              && "Case condition must evaluate to an integer constant.");
@@ -1491,7 +1494,7 @@
 // Transfer functions: logical operations ('&&', '||').
 //===----------------------------------------------------------------------===//
 
-void GRExprEngine::VisitLogicalExpr(BinaryOperator* B, ExplodedNode* Pred,
+void GRExprEngine::VisitLogicalExpr(const BinaryOperator* B, ExplodedNode* Pred,
                                     ExplodedNodeSet& Dst) {
 
   assert(B->getOpcode() == BinaryOperator::LAnd ||
@@ -1545,7 +1548,7 @@
 // Transfer functions: Loads and stores.
 //===----------------------------------------------------------------------===//
 
-void GRExprEngine::VisitBlockExpr(BlockExpr *BE, ExplodedNode *Pred,
+void GRExprEngine::VisitBlockExpr(const BlockExpr *BE, ExplodedNode *Pred,
                                   ExplodedNodeSet &Dst) {
 
   ExplodedNodeSet Tmp;
@@ -1561,18 +1564,18 @@
   CheckerVisit(BE, Dst, Tmp, false);
 }
 
-void GRExprEngine::VisitDeclRefExpr(DeclRefExpr *Ex, ExplodedNode *Pred,
+void GRExprEngine::VisitDeclRefExpr(const DeclRefExpr *Ex, ExplodedNode *Pred,
                                     ExplodedNodeSet &Dst, bool asLValue) {
   VisitCommonDeclRefExpr(Ex, Ex->getDecl(), Pred, Dst, asLValue);
 }
 
-void GRExprEngine::VisitBlockDeclRefExpr(BlockDeclRefExpr *Ex,
+void GRExprEngine::VisitBlockDeclRefExpr(const BlockDeclRefExpr *Ex,
                                          ExplodedNode *Pred,
                                     ExplodedNodeSet &Dst, bool asLValue) {
   VisitCommonDeclRefExpr(Ex, Ex->getDecl(), Pred, Dst, asLValue);
 }
 
-void GRExprEngine::VisitCommonDeclRefExpr(Expr *Ex, const NamedDecl *D,
+void GRExprEngine::VisitCommonDeclRefExpr(const Expr *Ex, const NamedDecl *D,
                                           ExplodedNode *Pred,
                                           ExplodedNodeSet &Dst, bool asLValue) {
 
@@ -1619,12 +1622,12 @@
 }
 
 /// VisitArraySubscriptExpr - Transfer function for array accesses
-void GRExprEngine::VisitArraySubscriptExpr(ArraySubscriptExpr* A,
+void GRExprEngine::VisitArraySubscriptExpr(const ArraySubscriptExpr* A,
                                            ExplodedNode* Pred,
                                            ExplodedNodeSet& Dst, bool asLValue){
 
-  Expr* Base = A->getBase()->IgnoreParens();
-  Expr* Idx  = A->getIdx()->IgnoreParens();
+  const Expr* Base = A->getBase()->IgnoreParens();
+  const Expr* Idx  = A->getIdx()->IgnoreParens();
   ExplodedNodeSet Tmp;
 
   if (Base->getType()->isVectorType()) {
@@ -1659,7 +1662,7 @@
 }
 
 /// VisitMemberExpr - Transfer function for member expressions.
-void GRExprEngine::VisitMemberExpr(MemberExpr* M, ExplodedNode* Pred,
+void GRExprEngine::VisitMemberExpr(const MemberExpr* M, ExplodedNode* Pred,
                                    ExplodedNodeSet& Dst, bool asLValue) {
 
   Expr* Base = M->getBase()->IgnoreParens();
@@ -1912,9 +1915,9 @@
   return false;
 }
 
-void GRExprEngine::VisitCall(CallExpr* CE, ExplodedNode* Pred,
-                             CallExpr::arg_iterator AI,
-                             CallExpr::arg_iterator AE,
+void GRExprEngine::VisitCall(const CallExpr* CE, ExplodedNode* Pred,
+                             CallExpr::const_arg_iterator AI,
+                             CallExpr::const_arg_iterator AE,
                              ExplodedNodeSet& Dst, bool asLValue) {
 
   // Determine the type of function we're calling (if available).
@@ -1961,7 +1964,7 @@
 
   // Now process the call itself.
   ExplodedNodeSet DstTmp;
-  Expr* Callee = CE->getCallee()->IgnoreParens();
+  const Expr* Callee = CE->getCallee()->IgnoreParens();
 
   for (ExplodedNodeSet::iterator NI=ArgsEvaluated.begin(),
                                  NE=ArgsEvaluated.end(); NI != NE; ++NI) {
@@ -2054,7 +2057,7 @@
   = std::pair<const void*,const void*>(&EagerlyAssumeTag,static_cast<void*>(0));
 
 void GRExprEngine::EvalEagerlyAssume(ExplodedNodeSet &Dst, ExplodedNodeSet &Src,
-                                     Expr *Ex) {
+                                     const Expr *Ex) {
   for (ExplodedNodeSet::iterator I=Src.begin(), E=Src.end(); I!=E; ++I) {
     ExplodedNode *Pred = *I;
 
@@ -2097,10 +2100,11 @@
 // Transfer function: Objective-C ivar references.
 //===----------------------------------------------------------------------===//
 
-void GRExprEngine::VisitObjCIvarRefExpr(ObjCIvarRefExpr* Ex, ExplodedNode* Pred,
+void GRExprEngine::VisitObjCIvarRefExpr(const ObjCIvarRefExpr* Ex, 
+                                        ExplodedNode* Pred,
                                         ExplodedNodeSet& Dst, bool asLValue) {
 
-  Expr* Base = cast<Expr>(Ex->getBase());
+  const Expr* Base = cast<Expr>(Ex->getBase());
   ExplodedNodeSet Tmp;
   Visit(Base, Pred, Tmp);
 
@@ -2120,7 +2124,7 @@
 // Transfer function: Objective-C fast enumeration 'for' statements.
 //===----------------------------------------------------------------------===//
 
-void GRExprEngine::VisitObjCForCollectionStmt(ObjCForCollectionStmt* S,
+void GRExprEngine::VisitObjCForCollectionStmt(const ObjCForCollectionStmt* S,
                                      ExplodedNode* Pred, ExplodedNodeSet& Dst) {
 
   // ObjCForCollectionStmts are processed in two places.  This method
@@ -2148,11 +2152,11 @@
   //    container is empty.  Thus this transfer function will by default
   //    result in state splitting.
 
-  Stmt* elem = S->getElement();
+  const Stmt* elem = S->getElement();
   SVal ElementV;
 
-  if (DeclStmt* DS = dyn_cast<DeclStmt>(elem)) {
-    VarDecl* ElemD = cast<VarDecl>(DS->getSingleDecl());
+  if (const DeclStmt* DS = dyn_cast<DeclStmt>(elem)) {
+    const VarDecl* ElemD = cast<VarDecl>(DS->getSingleDecl());
     assert (ElemD->getInit() == 0);
     ElementV = GetState(Pred)->getLValue(ElemD, Pred->getLocationContext());
     VisitObjCForCollectionStmtAux(S, Pred, Dst, ElementV);
@@ -2168,12 +2172,12 @@
   }
 }
 
-void GRExprEngine::VisitObjCForCollectionStmtAux(ObjCForCollectionStmt* S,
+void GRExprEngine::VisitObjCForCollectionStmtAux(const 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();
+  const Stmt* elem = S->getElement();
   ExplodedNodeSet Tmp;
   EvalLocation(Tmp, elem, Pred, GetState(Pred), ElementV, NULL, false);
 
@@ -2222,23 +2226,24 @@
 namespace {
 class ObjCMsgWLItem {
 public:
-  ObjCMessageExpr::arg_iterator I;
+  ObjCMessageExpr::const_arg_iterator I;
   ExplodedNode *N;
 
-  ObjCMsgWLItem(const ObjCMessageExpr::arg_iterator &i, ExplodedNode *n)
+  ObjCMsgWLItem(const ObjCMessageExpr::const_arg_iterator &i, ExplodedNode *n)
     : I(i), N(n) {}
 };
 } // end anonymous namespace
 
-void GRExprEngine::VisitObjCMessageExpr(ObjCMessageExpr* ME, ExplodedNode* Pred,
+void GRExprEngine::VisitObjCMessageExpr(const ObjCMessageExpr* ME, 
+                                        ExplodedNode* Pred,
                                         ExplodedNodeSet& Dst, bool asLValue){
 
   // Create a worklist to process both the arguments.
   llvm::SmallVector<ObjCMsgWLItem, 20> WL;
 
   // But first evaluate the receiver (if any).
-  ObjCMessageExpr::arg_iterator AI = ME->arg_begin(), AE = ME->arg_end();
-  if (Expr *Receiver = ME->getInstanceReceiver()) {
+  ObjCMessageExpr::const_arg_iterator AI = ME->arg_begin(), AE = ME->arg_end();
+  if (const Expr *Receiver = ME->getInstanceReceiver()) {
     ExplodedNodeSet Tmp;
     Visit(Receiver, Pred, Tmp);
 
@@ -2405,8 +2410,9 @@
 // Transfer functions: Miscellaneous statements.
 //===----------------------------------------------------------------------===//
 
-void GRExprEngine::VisitCast(CastExpr *CastE, Expr *Ex, ExplodedNode *Pred,
-                             ExplodedNodeSet &Dst, bool asLValue) {
+void GRExprEngine::VisitCast(const CastExpr *CastE, const Expr *Ex, 
+                             ExplodedNode *Pred, ExplodedNodeSet &Dst, 
+                             bool asLValue) {
   ExplodedNodeSet S1;
   QualType T = CastE->getType();
   QualType ExTy = Ex->getType();
@@ -2495,11 +2501,12 @@
   }
 }
 
-void GRExprEngine::VisitCompoundLiteralExpr(CompoundLiteralExpr* CL,
+void GRExprEngine::VisitCompoundLiteralExpr(const CompoundLiteralExpr* CL,
                                             ExplodedNode* Pred,
                                             ExplodedNodeSet& Dst,
                                             bool asLValue) {
-  InitListExpr* ILE = cast<InitListExpr>(CL->getInitializer()->IgnoreParens());
+  const InitListExpr* ILE 
+    = cast<InitListExpr>(CL->getInitializer()->IgnoreParens());
   ExplodedNodeSet Tmp;
   Visit(ILE, Pred, Tmp);
 
@@ -2517,17 +2524,17 @@
   }
 }
 
-void GRExprEngine::VisitDeclStmt(DeclStmt *DS, ExplodedNode *Pred,
+void GRExprEngine::VisitDeclStmt(const DeclStmt *DS, ExplodedNode *Pred,
                                  ExplodedNodeSet& Dst) {
 
   // The CFG has one DeclStmt per Decl.
-  Decl* D = *DS->decl_begin();
+  const 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());
+  const 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.
@@ -2580,10 +2587,10 @@
   }
 }
 
-void GRExprEngine::VisitCondInit(VarDecl *VD, Stmt *S,
+void GRExprEngine::VisitCondInit(const VarDecl *VD, const Stmt *S,
                                  ExplodedNode *Pred, ExplodedNodeSet& Dst) {
 
-  Expr* InitEx = VD->getInit();
+  const Expr* InitEx = VD->getInit();
   ExplodedNodeSet Tmp;
   Visit(InitEx, Pred, Tmp);
 
@@ -2614,16 +2621,16 @@
 public:
   llvm::ImmutableList<SVal> Vals;
   ExplodedNode* N;
-  InitListExpr::reverse_iterator Itr;
+  InitListExpr::const_reverse_iterator Itr;
 
   InitListWLItem(ExplodedNode* n, llvm::ImmutableList<SVal> vals,
-                 InitListExpr::reverse_iterator itr)
+                 InitListExpr::const_reverse_iterator itr)
   : Vals(vals), N(n), Itr(itr) {}
 };
 }
 
 
-void GRExprEngine::VisitInitListExpr(InitListExpr* E, ExplodedNode* Pred,
+void GRExprEngine::VisitInitListExpr(const InitListExpr* E, ExplodedNode* Pred,
                                      ExplodedNodeSet& Dst) {
 
   const GRState* state = GetState(Pred);
@@ -2645,7 +2652,7 @@
     llvm::SmallVector<InitListWLItem, 10> WorkList;
     WorkList.reserve(NumInitElements);
     WorkList.push_back(InitListWLItem(Pred, StartVals, E->rbegin()));
-    InitListExpr::reverse_iterator ItrEnd = E->rend();
+    InitListExpr::const_reverse_iterator ItrEnd = E->rend();
     assert(!(E->rbegin() == E->rend()));
 
     // Process the worklist until it is empty.
@@ -2656,7 +2663,7 @@
       ExplodedNodeSet Tmp;
       Visit(*X.Itr, X.N, Tmp);
 
-      InitListExpr::reverse_iterator NewItr = X.Itr + 1;
+      InitListExpr::const_reverse_iterator NewItr = X.Itr + 1;
 
       for (ExplodedNodeSet::iterator NI=Tmp.begin(),NE=Tmp.end();NI!=NE;++NI) {
         // Get the last initializer value.
@@ -2688,7 +2695,7 @@
   if (Loc::IsLocType(T) || T->isIntegerType()) {
     assert (E->getNumInits() == 1);
     ExplodedNodeSet Tmp;
-    Expr* Init = E->getInit(0);
+    const Expr* Init = E->getInit(0);
     Visit(Init, Pred, Tmp);
     for (ExplodedNodeSet::iterator I=Tmp.begin(), EI=Tmp.end(); I != EI; ++I) {
       state = GetState(*I);
@@ -2701,7 +2708,7 @@
 }
 
 /// VisitSizeOfAlignOfExpr - Transfer function for sizeof(type).
-void GRExprEngine::VisitSizeOfAlignOfExpr(SizeOfAlignOfExpr* Ex,
+void GRExprEngine::VisitSizeOfAlignOfExpr(const SizeOfAlignOfExpr* Ex,
                                           ExplodedNode* Pred,
                                           ExplodedNodeSet& Dst) {
   QualType T = Ex->getTypeOfArgument();
@@ -2724,7 +2731,7 @@
 
       // Get the size by getting the extent of the sub-expression.
       // First, visit the sub-expression to find its region.
-      Expr *Arg = Ex->getArgumentExpr();
+      const Expr *Arg = Ex->getArgumentExpr();
       ExplodedNodeSet Tmp;
       VisitLValue(Arg, Pred, Tmp);
 
@@ -2766,8 +2773,8 @@
               ValMgr.makeIntVal(amt.getQuantity(), Ex->getType())));
 }
 
-void GRExprEngine::VisitOffsetOfExpr(OffsetOfExpr* OOE, ExplodedNode* Pred,
-                                     ExplodedNodeSet& Dst) {
+void GRExprEngine::VisitOffsetOfExpr(const OffsetOfExpr* OOE, 
+                                     ExplodedNode* Pred, ExplodedNodeSet& Dst) {
   Expr::EvalResult Res;
   if (OOE->Evaluate(Res, getContext()) && Res.Val.isInt()) {
     const APSInt &IV = Res.Val.getInt();
@@ -2782,7 +2789,8 @@
   Dst.Add(Pred);
 }
 
-void GRExprEngine::VisitUnaryOperator(UnaryOperator* U, ExplodedNode* Pred,
+void GRExprEngine::VisitUnaryOperator(const UnaryOperator* U, 
+                                      ExplodedNode* Pred,
                                       ExplodedNodeSet& Dst, bool asLValue) {
 
   switch (U->getOpcode()) {
@@ -2792,7 +2800,7 @@
 
     case UnaryOperator::Deref: {
 
-      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      const Expr* Ex = U->getSubExpr()->IgnoreParens();
       ExplodedNodeSet Tmp;
       Visit(Ex, Pred, Tmp);
 
@@ -2813,7 +2821,7 @@
 
     case UnaryOperator::Real: {
 
-      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      const Expr* Ex = U->getSubExpr()->IgnoreParens();
       ExplodedNodeSet Tmp;
       Visit(Ex, Pred, Tmp);
 
@@ -2837,7 +2845,7 @@
 
     case UnaryOperator::Imag: {
 
-      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      const Expr* Ex = U->getSubExpr()->IgnoreParens();
       ExplodedNodeSet Tmp;
       Visit(Ex, Pred, Tmp);
 
@@ -2882,7 +2890,7 @@
       // generate an extra node that just propagates the value of the
       // subexpression.
 
-      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      const Expr* Ex = U->getSubExpr()->IgnoreParens();
       ExplodedNodeSet Tmp;
 
       if (asLValue)
@@ -2901,7 +2909,7 @@
     case UnaryOperator::AddrOf: {
 
       assert(!asLValue);
-      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      const Expr* Ex = U->getSubExpr()->IgnoreParens();
       ExplodedNodeSet Tmp;
       VisitLValue(Ex, Pred, Tmp);
 
@@ -2920,7 +2928,7 @@
     case UnaryOperator::Not: {
 
       assert (!asLValue);
-      Expr* Ex = U->getSubExpr()->IgnoreParens();
+      const Expr* Ex = U->getSubExpr()->IgnoreParens();
       ExplodedNodeSet Tmp;
       Visit(Ex, Pred, Tmp);
 
@@ -2996,7 +3004,7 @@
 
   assert (U->isIncrementDecrementOp());
   ExplodedNodeSet Tmp;
-  Expr* Ex = U->getSubExpr()->IgnoreParens();
+  const Expr* Ex = U->getSubExpr()->IgnoreParens();
   VisitLValue(Ex, Pred, Tmp);
 
   for (ExplodedNodeSet::iterator I = Tmp.begin(), E = Tmp.end(); I!=E; ++I) {
@@ -3071,14 +3079,14 @@
   }
 }
 
-void GRExprEngine::VisitAsmStmt(AsmStmt* A, ExplodedNode* Pred,
+void GRExprEngine::VisitAsmStmt(const 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,
+void GRExprEngine::VisitAsmStmtHelperOutputs(const AsmStmt* A,
+                                             AsmStmt::const_outputs_iterator I,
+                                             AsmStmt::const_outputs_iterator E,
                                      ExplodedNode* Pred, ExplodedNodeSet& Dst) {
   if (I == E) {
     VisitAsmStmtHelperInputs(A, A->begin_inputs(), A->end_inputs(), Pred, Dst);
@@ -3094,9 +3102,9 @@
     VisitAsmStmtHelperOutputs(A, I, E, *NI, Dst);
 }
 
-void GRExprEngine::VisitAsmStmtHelperInputs(AsmStmt* A,
-                                            AsmStmt::inputs_iterator I,
-                                            AsmStmt::inputs_iterator E,
+void GRExprEngine::VisitAsmStmtHelperInputs(const AsmStmt* A,
+                                            AsmStmt::const_inputs_iterator I,
+                                            AsmStmt::const_inputs_iterator E,
                                             ExplodedNode* Pred,
                                             ExplodedNodeSet& Dst) {
   if (I == E) {
@@ -3110,7 +3118,7 @@
 
     const GRState* state = GetState(Pred);
 
-    for (AsmStmt::outputs_iterator OI = A->begin_outputs(),
+    for (AsmStmt::const_outputs_iterator OI = A->begin_outputs(),
                                    OE = A->end_outputs(); OI != OE; ++OI) {
 
       SVal X = state->getSVal(*OI);
@@ -3133,10 +3141,10 @@
     VisitAsmStmtHelperInputs(A, I, E, *NI, Dst);
 }
 
-void GRExprEngine::VisitReturnStmt(ReturnStmt *RS, ExplodedNode *Pred,
+void GRExprEngine::VisitReturnStmt(const ReturnStmt *RS, ExplodedNode *Pred,
                                    ExplodedNodeSet &Dst) {
   ExplodedNodeSet Src;
-  if (Expr *RetE = RS->getRetValue()) {
+  if (const Expr *RetE = RS->getRetValue()) {
     // Record the returned expression in the state. It will be used in
     // ProcessCallExit to bind the return value to the call expr.
     {
@@ -3181,7 +3189,7 @@
 // Transfer functions: Binary operators.
 //===----------------------------------------------------------------------===//
 
-void GRExprEngine::VisitBinaryOperator(BinaryOperator* B,
+void GRExprEngine::VisitBinaryOperator(const BinaryOperator* B,
                                        ExplodedNode* Pred,
                                        ExplodedNodeSet& Dst, bool asLValue) {
 
@@ -3471,7 +3479,7 @@
         Out << "Edge: (B" << E.getSrc()->getBlockID() << ", B"
             << E.getDst()->getBlockID()  << ')';
 
-        if (Stmt* T = E.getSrc()->getTerminator()) {
+        if (const Stmt* T = E.getSrc()->getTerminator()) {
 
           SourceLocation SLoc = T->getLocStart();
 
@@ -3487,15 +3495,15 @@
           }
 
           if (isa<SwitchStmt>(T)) {
-            Stmt* Label = E.getDst()->getLabel();
+            const Stmt* Label = E.getDst()->getLabel();
 
             if (Label) {
-              if (CaseStmt* C = dyn_cast<CaseStmt>(Label)) {
+              if (const CaseStmt* C = dyn_cast<CaseStmt>(Label)) {
                 Out << "\\lcase ";
                 LangOptions LO; // FIXME.
                 C->getLHS()->printPretty(Out, 0, PrintingPolicy(LO));
 
-                if (Stmt* RHS = C->getRHS()) {
+                if (const Stmt* RHS = C->getRHS()) {
                   Out << " .. ";
                   RHS->printPretty(Out, 0, PrintingPolicy(LO));
                 }
diff --git a/lib/Checker/UndefBranchChecker.cpp b/lib/Checker/UndefBranchChecker.cpp
index 9088345..1ff0641 100644
--- a/lib/Checker/UndefBranchChecker.cpp
+++ b/lib/Checker/UndefBranchChecker.cpp
@@ -29,27 +29,28 @@
 
     FindUndefExpr(GRStateManager& V, const GRState* S) : VM(V), St(S) {}
 
-    Expr* FindExpr(Expr* Ex) {
+    const Expr* FindExpr(const Expr* Ex) {
       if (!MatchesCriteria(Ex))
         return 0;
 
-      for (Stmt::child_iterator I=Ex->child_begin(), E=Ex->child_end();I!=E;++I)
-        if (Expr* ExI = dyn_cast_or_null<Expr>(*I)) {
-          Expr* E2 = FindExpr(ExI);
+      for (Stmt::const_child_iterator I = Ex->child_begin(), 
+                                      E = Ex->child_end();I!=E;++I)
+        if (const Expr* ExI = dyn_cast_or_null<Expr>(*I)) {
+          const Expr* E2 = FindExpr(ExI);
           if (E2) return E2;
         }
 
       return Ex;
     }
 
-    bool MatchesCriteria(Expr* Ex) { return St->getSVal(Ex).isUndef(); }
+    bool MatchesCriteria(const Expr* Ex) { return St->getSVal(Ex).isUndef(); }
   };
 
 public:
   UndefBranchChecker() : BT(0) {}
   static void *getTag();
   void VisitBranchCondition(GRBranchNodeBuilder &Builder, GRExprEngine &Eng,
-                            Stmt *Condition, void *tag);
+                            const Stmt *Condition, void *tag);
 };
 
 }
@@ -65,7 +66,7 @@
 
 void UndefBranchChecker::VisitBranchCondition(GRBranchNodeBuilder &Builder, 
                                               GRExprEngine &Eng,
-                                              Stmt *Condition, void *tag) {
+                                              const Stmt *Condition, void *tag){
   const GRState *state = Builder.getState();
   SVal X = state->getSVal(Condition);
   if (X.isUndef()) {
@@ -81,7 +82,7 @@
       // subexpressions and roughly look for the most nested subexpression
       // that binds to Undefined.  We then highlight that expression's range.
       BlockEdge B = cast<BlockEdge>(N->getLocation());
-      Expr* Ex = cast<Expr>(B.getSrc()->getTerminatorCondition());
+      const Expr* Ex = cast<Expr>(B.getSrc()->getTerminatorCondition());
       assert (Ex && "Block must have a terminator.");
 
       // Get the predecessor node and check if is a PostStmt with the Stmt