Add 'StoreRef' smart pointer to allow more fine-grain memory lifetime control of Store objects.

This yields a minor memory reduction (for larger functions) on Sqlite at the cost of slightly
higher memory usage on some functions because of the increased size of GRState (which can be optimized).

I expect the real memory savings from this enhancement will come when we aggressively
canabilize more of the ExplodedGraph.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@126012 91177308-0d34-0410-b5e6-96231b3b80d8

5 files changed, 258 insertions, 228 deletions

diff --git a/lib/StaticAnalyzer/Core/BasicStore.cpp b/lib/StaticAnalyzer/Core/BasicStore.cpp
index 987e790585..98365e7f4e 100644
--- a/lib/StaticAnalyzer/Core/BasicStore.cpp
+++ b/lib/StaticAnalyzer/Core/BasicStore.cpp
@@ -48,24 +48,25 @@ public:
 
   SVal Retrieve(Store store, Loc loc, QualType T = QualType());
 
-  Store invalidateRegion(Store store, const MemRegion *R, const Expr *E,
-                         unsigned Count, InvalidatedSymbols *IS);
+  StoreRef invalidateRegion(Store store, const MemRegion *R, const Expr *E,
+                            unsigned Count, InvalidatedSymbols *IS);
 
-  Store invalidateRegions(Store store, const MemRegion * const *Begin,
-                          const MemRegion * const *End, const Expr *E,
-                          unsigned Count, InvalidatedSymbols *IS,
-                          bool invalidateGlobals, InvalidatedRegions *Regions);
+  StoreRef invalidateRegions(Store store, const MemRegion * const *Begin,
+                             const MemRegion * const *End, const Expr *E,
+                             unsigned Count, InvalidatedSymbols *IS,
+                             bool invalidateGlobals,
+                             InvalidatedRegions *Regions);
 
-  Store scanForIvars(Stmt *B, const Decl* SelfDecl,
-                     const MemRegion *SelfRegion, Store St);
+  StoreRef scanForIvars(Stmt *B, const Decl* SelfDecl,
+                        const MemRegion *SelfRegion, Store St);
 
-  Store Bind(Store St, Loc loc, SVal V);
-  Store Remove(Store St, Loc loc);
-  Store getInitialStore(const LocationContext *InitLoc);
+  StoreRef Bind(Store St, Loc loc, SVal V);
+  StoreRef Remove(Store St, Loc loc);
+  StoreRef getInitialStore(const LocationContext *InitLoc);
 
-  Store BindCompoundLiteral(Store store, const CompoundLiteralExpr*,
+  StoreRef BindCompoundLiteral(Store store, const CompoundLiteralExpr*,
                             const LocationContext*, SVal val) {
-    return store;
+    return StoreRef(store, *this);
   }
 
   /// ArrayToPointer - Used by ExprEngine::VistCast to handle implicit
@@ -74,21 +75,21 @@ public:
 
   /// removeDeadBindings - Scans a BasicStore of 'state' for dead values.
   ///  It updatees the GRState object in place with the values removed.
-  Store removeDeadBindings(Store store, const StackFrameContext *LCtx,
-                           SymbolReaper& SymReaper,
+  StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx,
+                              SymbolReaper& SymReaper,
                           llvm::SmallVectorImpl<const MemRegion*>& RegionRoots);
 
   void iterBindings(Store store, BindingsHandler& f);
 
-  Store BindDecl(Store store, const VarRegion *VR, SVal InitVal) {
+  StoreRef BindDecl(Store store, const VarRegion *VR, SVal InitVal) {
     return BindDeclInternal(store, VR, &InitVal);
   }
 
-  Store BindDeclWithNoInit(Store store, const VarRegion *VR) {
+  StoreRef BindDeclWithNoInit(Store store, const VarRegion *VR) {
     return BindDeclInternal(store, VR, 0);
   }
 
-  Store BindDeclInternal(Store store, const VarRegion *VR, SVal *InitVal);
+  StoreRef BindDeclInternal(Store store, const VarRegion *VR, SVal *InitVal);
 
   static inline BindingsTy GetBindings(Store store) {
     return BindingsTy(static_cast<const BindingsTy::TreeTy*>(store));
@@ -210,9 +211,9 @@ SVal BasicStoreManager::Retrieve(Store store, Loc loc, QualType T) {
   return UnknownVal();
 }
 
-Store BasicStoreManager::Bind(Store store, Loc loc, SVal V) {
+StoreRef BasicStoreManager::Bind(Store store, Loc loc, SVal V) {
   if (isa<loc::ConcreteInt>(loc))
-    return store;
+    return StoreRef(store, *this);
 
   const MemRegion* R = cast<loc::MemRegionVal>(loc).getRegion();
 
@@ -220,7 +221,7 @@ Store BasicStoreManager::Bind(Store store, Loc loc, SVal V) {
   //  that is used to derive other symbols.
   if (isa<NonStaticGlobalSpaceRegion>(R)) {
     BindingsTy B = GetBindings(store);
-    return VBFactory.add(B, R, V).getRoot();
+    return StoreRef(VBFactory.add(B, R, V).getRoot(), *this);
   }
 
   // Special case: handle store of pointer values (Loc) to pointers via
@@ -236,14 +237,14 @@ Store BasicStoreManager::Bind(Store store, Loc loc, SVal V) {
     }
 
   if (!(isa<VarRegion>(R) || isa<ObjCIvarRegion>(R) || isa<CXXThisRegion>(R)))
-    return store;
+    return StoreRef(store, *this);
 
   const TypedRegion *TyR = cast<TypedRegion>(R);
 
   // Do not bind to arrays.  We need to explicitly check for this so that
   // we do not encounter any weirdness of trying to load/store from arrays.
   if (TyR->isBoundable() && TyR->getValueType()->isArrayType())
-    return store;
+    return StoreRef(store, *this);
 
   if (nonloc::LocAsInteger *X = dyn_cast<nonloc::LocAsInteger>(&V)) {
     // Only convert 'V' to a location iff the underlying region type
@@ -257,31 +258,31 @@ Store BasicStoreManager::Bind(Store store, Loc loc, SVal V) {
   }
 
   BindingsTy B = GetBindings(store);
-  return V.isUnknown()
-    ? VBFactory.remove(B, R).getRoot()
-    : VBFactory.add(B, R, V).getRoot();
+  return StoreRef(V.isUnknown()
+                    ? VBFactory.remove(B, R).getRoot()
+                    : VBFactory.add(B, R, V).getRoot(), *this);
 }
 
-Store BasicStoreManager::Remove(Store store, Loc loc) {
+StoreRef BasicStoreManager::Remove(Store store, Loc loc) {
   switch (loc.getSubKind()) {
     case loc::MemRegionKind: {
       const MemRegion* R = cast<loc::MemRegionVal>(loc).getRegion();
 
       if (!(isa<VarRegion>(R) || isa<ObjCIvarRegion>(R) ||
           isa<CXXThisRegion>(R)))
-        return store;
+        return StoreRef(store, *this);
 
-      return VBFactory.remove(GetBindings(store), R).getRoot();
+      return StoreRef(VBFactory.remove(GetBindings(store), R).getRoot(), *this);
     }
     default:
       assert ("Remove for given Loc type not yet implemented.");
-      return store;
+      return StoreRef(store, *this);
   }
 }
 
-Store BasicStoreManager::removeDeadBindings(Store store,
-                                            const StackFrameContext *LCtx,
-                                            SymbolReaper& SymReaper,
+StoreRef BasicStoreManager::removeDeadBindings(Store store,
+                                               const StackFrameContext *LCtx,
+                                               SymbolReaper& SymReaper,
                            llvm::SmallVectorImpl<const MemRegion*>& RegionRoots)
 {
   BindingsTy B = GetBindings(store);
@@ -347,11 +348,12 @@ Store BasicStoreManager::removeDeadBindings(Store store,
   }
 
   // Remove dead variable bindings.
+  StoreRef newStore(store, *this);
   for (BindingsTy::iterator I=B.begin(), E=B.end(); I!=E ; ++I) {
     const MemRegion* R = I.getKey();
 
     if (!Marked.count(R)) {
-      store = Remove(store, svalBuilder.makeLoc(R));
+      newStore = Remove(newStore.getStore(), svalBuilder.makeLoc(R));
       SVal X = I.getData();
 
       for (symbol_iterator SI=X.symbol_begin(), SE=X.symbol_end(); SI!=SE; ++SI)
@@ -359,11 +361,15 @@ Store BasicStoreManager::removeDeadBindings(Store store,
     }
   }
 
-  return store;
+  return newStore;
 }
 
-Store BasicStoreManager::scanForIvars(Stmt *B, const Decl* SelfDecl,
-                                      const MemRegion *SelfRegion, Store St) {
+StoreRef BasicStoreManager::scanForIvars(Stmt *B, const Decl* SelfDecl,
+                                         const MemRegion *SelfRegion,
+                                         Store St) {
+  
+  StoreRef newStore(St, *this);
+
   for (Stmt::child_iterator CI=B->child_begin(), CE=B->child_end();
        CI != CE; ++CI) {
 
@@ -379,24 +385,24 @@ Store BasicStoreManager::scanForIvars(Stmt *B, const Decl* SelfDecl,
           const ObjCIvarRegion *IVR = MRMgr.getObjCIvarRegion(IV->getDecl(),
                                                          SelfRegion);
           SVal X = svalBuilder.getRegionValueSymbolVal(IVR);
-          St = Bind(St, svalBuilder.makeLoc(IVR), X);
+          newStore = Bind(newStore.getStore(), svalBuilder.makeLoc(IVR), X);
         }
       }
     }
     else
-      St = scanForIvars(*CI, SelfDecl, SelfRegion, St);
+      newStore = scanForIvars(*CI, SelfDecl, SelfRegion, newStore.getStore());
   }
 
-  return St;
+  return newStore;
 }
 
-Store BasicStoreManager::getInitialStore(const LocationContext *InitLoc) {
+StoreRef BasicStoreManager::getInitialStore(const LocationContext *InitLoc) {
   // The LiveVariables information already has a compilation of all VarDecls
   // used in the function.  Iterate through this set, and "symbolicate"
   // any VarDecl whose value originally comes from outside the function.
   typedef LiveVariables::AnalysisDataTy LVDataTy;
   LVDataTy& D = InitLoc->getLiveVariables()->getAnalysisData();
-  Store St = VBFactory.getEmptyMap().getRoot();
+  StoreRef St(VBFactory.getEmptyMap().getRoot(), *this);
 
   for (LVDataTy::decl_iterator I=D.begin_decl(), E=D.end_decl(); I != E; ++I) {
     const NamedDecl* ND = I->first;
@@ -412,10 +418,11 @@ Store BasicStoreManager::getInitialStore(const LocationContext *InitLoc) {
           const MemRegion *SelfRegion =
             svalBuilder.getRegionValueSymbolVal(VR).getAsRegion();
           assert(SelfRegion);
-          St = Bind(St, svalBuilder.makeLoc(VR), loc::MemRegionVal(SelfRegion));
+          St = Bind(St.getStore(), svalBuilder.makeLoc(VR),
+                    loc::MemRegionVal(SelfRegion));
           // Scan the method for ivar references.  While this requires an
           // entire AST scan, the cost should not be high in practice.
-          St = scanForIvars(MD->getBody(), PD, SelfRegion, St);
+          St = scanForIvars(MD->getBody(), PD, SelfRegion, St.getStore());
         }
       }
     }
@@ -427,22 +434,23 @@ Store BasicStoreManager::getInitialStore(const LocationContext *InitLoc) {
     MemRegionManager &RegMgr = svalBuilder.getRegionManager();
     const CXXThisRegion *ThisR = RegMgr.getCXXThisRegion(ThisT, InitLoc);
     SVal ThisV = svalBuilder.getRegionValueSymbolVal(ThisR);
-    St = Bind(St, svalBuilder.makeLoc(ThisR), ThisV);
+    St = Bind(St.getStore(), svalBuilder.makeLoc(ThisR), ThisV);
   }
 
   return St;
 }
 
-Store BasicStoreManager::BindDeclInternal(Store store, const VarRegion* VR,
-                                          SVal* InitVal) {
+StoreRef BasicStoreManager::BindDeclInternal(Store store, const VarRegion* VR,
+                                             SVal* InitVal) {
 
   BasicValueFactory& BasicVals = StateMgr.getBasicVals();
   const VarDecl *VD = VR->getDecl();
+  StoreRef newStore(store, *this);
 
   // BasicStore does not model arrays and structs.
   if (VD->getType()->isArrayType() || VD->getType()->isStructureOrClassType())
-    return store;
-
+    return newStore;
+  
   if (VD->hasGlobalStorage()) {
     // Handle variables with global storage: extern, static, PrivateExtern.
 
@@ -465,13 +473,13 @@ Store BasicStoreManager::BindDeclInternal(Store store, const VarRegion* VR,
       if (!InitVal) {
         QualType T = VD->getType();
         if (Loc::isLocType(T))
-          store = Bind(store, loc::MemRegionVal(VR),
-                       loc::ConcreteInt(BasicVals.getValue(0, T)));
+          newStore = Bind(store, loc::MemRegionVal(VR),
+                          loc::ConcreteInt(BasicVals.getValue(0, T)));
         else if (T->isIntegerType() && T->isScalarType())
-          store = Bind(store, loc::MemRegionVal(VR),
-                       nonloc::ConcreteInt(BasicVals.getValue(0, T)));
+          newStore = Bind(store, loc::MemRegionVal(VR),
+                          nonloc::ConcreteInt(BasicVals.getValue(0, T)));
       } else {
-        store = Bind(store, loc::MemRegionVal(VR), *InitVal);
+          newStore = Bind(store, loc::MemRegionVal(VR), *InitVal);
       }
     }
   } else {
@@ -481,11 +489,11 @@ Store BasicStoreManager::BindDeclInternal(Store store, const VarRegion* VR,
     if ((T->isScalarType() || T->isReferenceType()) &&
         svalBuilder.getSymbolManager().canSymbolicate(T)) {
       SVal V = InitVal ? *InitVal : UndefinedVal();
-      store = Bind(store, loc::MemRegionVal(VR), V);
+      newStore = Bind(store, loc::MemRegionVal(VR), V);
     }
   }
 
-  return store;
+  return newStore;
 }
 
 void BasicStoreManager::print(Store store, llvm::raw_ostream& Out,
@@ -523,19 +531,21 @@ StoreManager::BindingsHandler::~BindingsHandler() {}
 //===----------------------------------------------------------------------===//
 
 
-Store BasicStoreManager::invalidateRegions(Store store,
-                                           const MemRegion * const *I,
-                                           const MemRegion * const *End,
-                                           const Expr *E, unsigned Count,
-                                           InvalidatedSymbols *IS,
-                                           bool invalidateGlobals,
-                                           InvalidatedRegions *Regions) {
+StoreRef BasicStoreManager::invalidateRegions(Store store,
+                                              const MemRegion * const *I,
+                                              const MemRegion * const *End,
+                                              const Expr *E, unsigned Count,
+                                              InvalidatedSymbols *IS,
+                                              bool invalidateGlobals,
+                                              InvalidatedRegions *Regions) {
+  StoreRef newStore(store, *this);
+  
   if (invalidateGlobals) {
     BindingsTy B = GetBindings(store);
     for (BindingsTy::iterator I=B.begin(), End=B.end(); I != End; ++I) {
       const MemRegion *R = I.getKey();
       if (isa<NonStaticGlobalSpaceRegion>(R->getMemorySpace()))
-        store = invalidateRegion(store, R, E, Count, IS);
+        newStore = invalidateRegion(newStore.getStore(), R, E, Count, IS);
     }
   }
 
@@ -546,7 +556,7 @@ Store BasicStoreManager::invalidateRegions(Store store,
       if (isa<NonStaticGlobalSpaceRegion>(R->getMemorySpace()))
         continue;
     }
-    store = invalidateRegion(store, *I, E, Count, IS);
+    newStore = invalidateRegion(newStore.getStore(), *I, E, Count, IS);
     if (Regions)
       Regions->push_back(R);
   }
@@ -561,24 +571,24 @@ Store BasicStoreManager::invalidateRegions(Store store,
                                   /* symbol type, doesn't matter */ Ctx.IntTy,
                                   Count);
 
-    store = Bind(store, loc::MemRegionVal(GS), V);
+    newStore = Bind(newStore.getStore(), loc::MemRegionVal(GS), V);
     if (Regions)
       Regions->push_back(GS);
   }
 
-  return store;
+  return newStore;
 }
 
 
-Store BasicStoreManager::invalidateRegion(Store store,
-                                          const MemRegion *R,
-                                          const Expr *E,
-                                          unsigned Count,
-                                          InvalidatedSymbols *IS) {
+StoreRef BasicStoreManager::invalidateRegion(Store store,
+                                             const MemRegion *R,
+                                             const Expr *E,
+                                             unsigned Count,
+                                             InvalidatedSymbols *IS) {
   R = R->StripCasts();
 
   if (!(isa<VarRegion>(R) || isa<ObjCIvarRegion>(R)))
-      return store;
+      return StoreRef(store, *this);
 
   if (IS) {
     BindingsTy B = GetBindings(store);
diff --git a/lib/StaticAnalyzer/Core/FlatStore.cpp b/lib/StaticAnalyzer/Core/FlatStore.cpp
index c3da72af5a..99a5eadaca 100644
--- a/lib/StaticAnalyzer/Core/FlatStore.cpp
+++ b/lib/StaticAnalyzer/Core/FlatStore.cpp
@@ -31,13 +31,13 @@ public:
       BVFactory(mgr.getAllocator()) {}
 
   SVal Retrieve(Store store, Loc L, QualType T);
-  Store Bind(Store store, Loc L, SVal val);
-  Store Remove(Store St, Loc L);
-  Store BindCompoundLiteral(Store store, const CompoundLiteralExpr* cl,
+  StoreRef Bind(Store store, Loc L, SVal val);
+  StoreRef Remove(Store St, Loc L);
+  StoreRef BindCompoundLiteral(Store store, const CompoundLiteralExpr* cl,
                             const LocationContext *LC, SVal v);
 
-  Store getInitialStore(const LocationContext *InitLoc) {
-    return RBFactory.getEmptyMap().getRoot();
+  StoreRef getInitialStore(const LocationContext *InitLoc) {
+    return StoreRef(RBFactory.getEmptyMap().getRoot(), *this);
   }
 
   SubRegionMap *getSubRegionMap(Store store) {
@@ -45,22 +45,23 @@ public:
   }
 
   SVal ArrayToPointer(Loc Array);
-  Store removeDeadBindings(Store store, const StackFrameContext *LCtx,
-                           SymbolReaper& SymReaper,
-                         llvm::SmallVectorImpl<const MemRegion*>& RegionRoots){
-    return store;
+  StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx,
+                              SymbolReaper& SymReaper,
+                          llvm::SmallVectorImpl<const MemRegion*>& RegionRoots){
+    return StoreRef(store, *this);
   }
 
-  Store BindDecl(Store store, const VarRegion *VR, SVal initVal);
+  StoreRef BindDecl(Store store, const VarRegion *VR, SVal initVal);
 
-  Store BindDeclWithNoInit(Store store, const VarRegion *VR);
+  StoreRef BindDeclWithNoInit(Store store, const VarRegion *VR);
 
   typedef llvm::DenseSet<SymbolRef> InvalidatedSymbols;
   
-  Store invalidateRegions(Store store, const MemRegion * const *I,
-                          const MemRegion * const *E, const Expr *Ex,
-                          unsigned Count, InvalidatedSymbols *IS,
-                          bool invalidateGlobals, InvalidatedRegions *Regions);
+  StoreRef invalidateRegions(Store store, const MemRegion * const *I,
+                             const MemRegion * const *E, const Expr *Ex,
+                             unsigned Count, InvalidatedSymbols *IS,
+                             bool invalidateGlobals,
+                             InvalidatedRegions *Regions);
 
   void print(Store store, llvm::raw_ostream& Out, const char* nl, 
              const char *sep);
@@ -115,7 +116,7 @@ SVal FlatStoreManager::RetrieveRegionWithNoBinding(const MemRegion *R,
     return svalBuilder.getRegionValueSymbolVal(cast<TypedRegion>(R));
 }
 
-Store FlatStoreManager::Bind(Store store, Loc L, SVal val) {
+StoreRef FlatStoreManager::Bind(Store store, Loc L, SVal val) {
   const MemRegion *R = cast<loc::MemRegionVal>(L).getRegion();
   RegionBindings B = getRegionBindings(store);
   const BindingVal *V = B.lookup(R);
@@ -127,45 +128,45 @@ Store FlatStoreManager::Bind(Store store, Loc L, SVal val) {
   RegionInterval RI = RegionToInterval(R);
   // FIXME: FlatStore should handle regions with unknown intervals.
   if (!RI.R)
-    return B.getRoot();
+    return StoreRef(B.getRoot(), *this);
   BV = BVFactory.add(BV, RI.I, val);
   B = RBFactory.add(B, RI.R, BV);
-  return B.getRoot();
+  return StoreRef(B.getRoot(), *this);
 }
 
-Store FlatStoreManager::Remove(Store store, Loc L) {
-  return store;
+StoreRef FlatStoreManager::Remove(Store store, Loc L) {
+  return StoreRef(store, *this);
 }
 
-Store FlatStoreManager::BindCompoundLiteral(Store store,
+StoreRef FlatStoreManager::BindCompoundLiteral(Store store,
                                             const CompoundLiteralExpr* cl,
                                             const LocationContext *LC,
                                             SVal v) {
-  return store;
+  return StoreRef(store, *this);
 }
 
 SVal FlatStoreManager::ArrayToPointer(Loc Array) {
   return Array;
 }
 
-Store FlatStoreManager::BindDecl(Store store, const VarRegion *VR, 
-                                 SVal initVal) {
+StoreRef FlatStoreManager::BindDecl(Store store, const VarRegion *VR, 
+                                    SVal initVal) {
   return Bind(store, svalBuilder.makeLoc(VR), initVal);
 }
 
-Store FlatStoreManager::BindDeclWithNoInit(Store store, const VarRegion *VR) {
-  return store;
+StoreRef FlatStoreManager::BindDeclWithNoInit(Store store, const VarRegion *VR){
+  return StoreRef(store, *this);
 }
 
-Store FlatStoreManager::invalidateRegions(Store store,
-                                          const MemRegion * const *I,
-                                          const MemRegion * const *E,
-                                          const Expr *Ex, unsigned Count,
-                                          InvalidatedSymbols *IS,
-                                          bool invalidateGlobals,
-                                          InvalidatedRegions *Regions) {
+StoreRef FlatStoreManager::invalidateRegions(Store store,
+                                             const MemRegion * const *I,
+                                             const MemRegion * const *E,
+                                             const Expr *Ex, unsigned Count,
+                                             InvalidatedSymbols *IS,
+                                             bool invalidateGlobals,
+                                             InvalidatedRegions *Regions) {
   assert(false && "Not implemented");
-  return store;
+  return StoreRef(store, *this);
 }
 
 void FlatStoreManager::print(Store store, llvm::raw_ostream& Out, 
diff --git a/lib/StaticAnalyzer/Core/GRState.cpp b/lib/StaticAnalyzer/Core/GRState.cpp
index 80c8bbf195..7defecb366 100644
--- a/lib/StaticAnalyzer/Core/GRState.cpp
+++ b/lib/StaticAnalyzer/Core/GRState.cpp
@@ -53,7 +53,7 @@ GRStateManager::removeDeadBindings(const GRState* state,
                                            state, RegionRoots);
 
   // Clean up the store.
-  NewState.St = StoreMgr->removeDeadBindings(NewState.St, LCtx, 
+  NewState.St = StoreMgr->removeDeadBindings(NewState.getStore(), LCtx, 
                                              SymReaper, RegionRoots);
   state = getPersistentState(NewState);
   return ConstraintMgr->removeDeadBindings(state, SymReaper);
@@ -73,38 +73,39 @@ const GRState *GRStateManager::MarshalState(const GRState *state,
 const GRState *GRState::bindCompoundLiteral(const CompoundLiteralExpr* CL,
                                             const LocationContext *LC,
                                             SVal V) const {
-  Store new_store = 
-    getStateManager().StoreMgr->BindCompoundLiteral(St, CL, LC, V);
-  return makeWithStore(new_store);
+  const StoreRef &newStore = 
+    getStateManager().StoreMgr->BindCompoundLiteral(getStore(), CL, LC, V);
+  return makeWithStore(newStore);
 }
 
 const GRState *GRState::bindDecl(const VarRegion* VR, SVal IVal) const {
-  Store new_store = getStateManager().StoreMgr->BindDecl(St, VR, IVal);
-  return makeWithStore(new_store);
+  const StoreRef &newStore =
+    getStateManager().StoreMgr->BindDecl(getStore(), VR, IVal);
+  return makeWithStore(newStore);
 }
 
 const GRState *GRState::bindDeclWithNoInit(const VarRegion* VR) const {
-  Store new_store = getStateManager().StoreMgr->BindDeclWithNoInit(St, VR);
-  return makeWithStore(new_store);
+  const StoreRef &newStore =
+    getStateManager().StoreMgr->BindDeclWithNoInit(getStore(), VR);
+  return makeWithStore(newStore);
 }
 
 const GRState *GRState::bindLoc(Loc LV, SVal V) const {
   GRStateManager &Mgr = getStateManager();
-  Store new_store = Mgr.StoreMgr->Bind(St, LV, V);
-  const GRState *new_state = makeWithStore(new_store);
-
+  const GRState *newState = makeWithStore(Mgr.StoreMgr->Bind(getStore(), 
+                                                             LV, V));
   const MemRegion *MR = LV.getAsRegion();
   if (MR && Mgr.getOwningEngine())
-    return Mgr.getOwningEngine()->processRegionChange(new_state, MR);
+    return Mgr.getOwningEngine()->processRegionChange(newState, MR);
 
-  return new_state;
+  return newState;
 }
 
 const GRState *GRState::bindDefault(SVal loc, SVal V) const {
   GRStateManager &Mgr = getStateManager();
   const MemRegion *R = cast<loc::MemRegionVal>(loc).getRegion();
-  Store new_store = Mgr.StoreMgr->BindDefault(St, R, V);
-  const GRState *new_state = makeWithStore(new_store);
+  const StoreRef &newStore = Mgr.StoreMgr->BindDefault(getStore(), R, V);
+  const GRState *new_state = makeWithStore(newStore);
   return Mgr.getOwningEngine() ? 
            Mgr.getOwningEngine()->processRegionChange(new_state, R) : 
            new_state;
@@ -120,39 +121,36 @@ const GRState *GRState::invalidateRegions(const MemRegion * const *Begin,
  
   if (Eng && Eng->wantsRegionChangeUpdate(this)) {
     StoreManager::InvalidatedRegions Regions;
-
-    Store new_store = Mgr.StoreMgr->invalidateRegions(St, Begin, End,
-                                                      E, Count, IS,
-                                                      invalidateGlobals,
-                                                      &Regions);
-    const GRState *new_state = makeWithStore(new_store);
-
-    return Eng->processRegionChanges(new_state,
+    const StoreRef &newStore
+      = Mgr.StoreMgr->invalidateRegions(getStore(), Begin, End, E, Count, IS,
+                                        invalidateGlobals, &Regions);
+    const GRState *newState = makeWithStore(newStore);
+    return Eng->processRegionChanges(newState,
                                      &Regions.front(),
                                      &Regions.back()+1);
   }
 
-  Store new_store = Mgr.StoreMgr->invalidateRegions(St, Begin, End,
-                                                    E, Count, IS,
-                                                    invalidateGlobals,
-                                                    NULL);
-  return makeWithStore(new_store);
+  const StoreRef &newStore =
+    Mgr.StoreMgr->invalidateRegions(getStore(), Begin, End, E, Count, IS,
+                                    invalidateGlobals, NULL);
+  return makeWithStore(newStore);
 }
 
 const GRState *GRState::unbindLoc(Loc LV) const {
   assert(!isa<loc::MemRegionVal>(LV) && "Use invalidateRegion instead.");
 
   Store OldStore = getStore();
-  Store NewStore = getStateManager().StoreMgr->Remove(OldStore, LV);
+  const StoreRef &newStore = getStateManager().StoreMgr->Remove(OldStore, LV);
 
-  if (NewStore == OldStore)
+  if (newStore.getStore() == OldStore)
     return this;
 
-  return makeWithStore(NewStore);
+  return makeWithStore(newStore);
 }
 
 const GRState *GRState::enterStackFrame(const StackFrameContext *frame) const {
-  Store new_store = getStateManager().StoreMgr->enterStackFrame(this, frame);
+  const StoreRef &new_store =
+    getStateManager().StoreMgr->enterStackFrame(this, frame);
   return makeWithStore(new_store);
 }
 
@@ -323,7 +321,7 @@ const GRState* GRStateManager::getPersistentState(GRState& State) {
   return newState;
 }
 
-const GRState* GRState::makeWithStore(Store store) const {
+const GRState* GRState::makeWithStore(const StoreRef &store) const {
   GRState NewSt = *this;
   NewSt.St = store;
   return getStateManager().getPersistentState(NewSt);
diff --git a/lib/StaticAnalyzer/Core/RegionStore.cpp b/lib/StaticAnalyzer/Core/RegionStore.cpp
index dc31715ccb..19e0e12572 100644
--- a/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -215,7 +215,7 @@ public:
   /// setImplicitDefaultValue - Set the default binding for the provided
   ///  MemRegion to the value implicitly defined for compound literals when
   ///  the value is not specified.
-  Store setImplicitDefaultValue(Store store, const MemRegion *R, QualType T);
+  StoreRef setImplicitDefaultValue(Store store, const MemRegion *R, QualType T);
 
   /// ArrayToPointer - Emulates the "decay" of an array to a pointer
   ///  type.  'Array' represents the lvalue of the array being decayed
@@ -228,21 +228,21 @@ public:
   /// For DerivedToBase casts, create a CXXBaseObjectRegion and return it.
   virtual SVal evalDerivedToBase(SVal derived, QualType basePtrType);
 
-  Store getInitialStore(const LocationContext *InitLoc) {
-    return RBFactory.getEmptyMap().getRoot();
+  StoreRef getInitialStore(const LocationContext *InitLoc) {
+    return StoreRef(RBFactory.getEmptyMap().getRootWithoutRetain(), *this);
   }
 
   //===-------------------------------------------------------------------===//
   // Binding values to regions.
   //===-------------------------------------------------------------------===//
 
-  Store invalidateRegions(Store store,
-                          const MemRegion * const *Begin,
-                          const MemRegion * const *End,
-                          const Expr *E, unsigned Count,
-                          InvalidatedSymbols *IS,
-                          bool invalidateGlobals,
-                          InvalidatedRegions *Regions);
+  StoreRef invalidateRegions(Store store,
+                             const MemRegion * const *Begin,
+                             const MemRegion * const *End,
+                             const Expr *E, unsigned Count,
+                             InvalidatedSymbols *IS,
+                             bool invalidateGlobals,
+                             InvalidatedRegions *Regions);
 
 public:   // Made public for helper classes.
 
@@ -268,35 +268,45 @@ public:   // Made public for helper classes.
 
 public: // Part of public interface to class.
 
-  Store Bind(Store store, Loc LV, SVal V);
+  StoreRef Bind(Store store, Loc LV, SVal V);
 
   // BindDefault is only used to initialize a region with a default value.
-  Store BindDefault(Store store, const MemRegion *R, SVal V) {
+  StoreRef BindDefault(Store store, const MemRegion *R, SVal V) {
     RegionBindings B = GetRegionBindings(store);
     assert(!lookup(B, R, BindingKey::Default));
     assert(!lookup(B, R, BindingKey::Direct));
-    return addBinding(B, R, BindingKey::Default, V).getRoot();
+    return StoreRef(addBinding(B, R, BindingKey::Default, V).getRootWithoutRetain(), *this);
   }
 
-  Store BindCompoundLiteral(Store store, const CompoundLiteralExpr* CL,
-                            const LocationContext *LC, SVal V);
+  StoreRef BindCompoundLiteral(Store store, const CompoundLiteralExpr* CL,
+                               const LocationContext *LC, SVal V);
 
-  Store BindDecl(Store store, const VarRegion *VR, SVal InitVal);
+  StoreRef BindDecl(Store store, const VarRegion *VR, SVal InitVal);
 
-  Store BindDeclWithNoInit(Store store, const VarRegion *) {
-    return store;
+  StoreRef BindDeclWithNoInit(Store store, const VarRegion *) {
+    return StoreRef(store, *this);
   }
 
   /// BindStruct - Bind a compound value to a structure.
-  Store BindStruct(Store store, const TypedRegion* R, SVal V);
+  StoreRef BindStruct(Store store, const TypedRegion* R, SVal V);
 
-  Store BindArray(Store store, const TypedRegion* R, SVal V);
+  StoreRef BindArray(Store store, const TypedRegion* R, SVal V);
 
   /// KillStruct - Set the entire struct to unknown.
-  Store KillStruct(Store store, const TypedRegion* R, SVal DefaultVal);
+  StoreRef KillStruct(Store store, const TypedRegion* R, SVal DefaultVal);
 
-  Store Remove(Store store, Loc LV);
+  StoreRef Remove(Store store, Loc LV);
 
+  void incrementReferenceCount(Store store) {
+    GetRegionBindings(store).manualRetain();    
+  }
+  
+  /// If the StoreManager supports it, decrement the reference count of
+  /// the specified Store object.  If the reference count hits 0, the memory
+  /// associated with the object is recycled.
+  void decrementReferenceCount(Store store) {
+    GetRegionBindings(store).manualRelease();
+  }
 
   //===------------------------------------------------------------------===//
   // Loading values from regions.
@@ -347,8 +357,8 @@ public: // Part of public interface to class.
   std::pair<Store, const MemRegion*>
   GetLazyBinding(RegionBindings B, const MemRegion *R);
 
-  Store CopyLazyBindings(nonloc::LazyCompoundVal V, Store store,
-                         const TypedRegion *R);
+  StoreRef CopyLazyBindings(nonloc::LazyCompoundVal V, Store store,
+                            const TypedRegion *R);
 
   //===------------------------------------------------------------------===//
   // State pruning.
@@ -356,11 +366,11 @@ public: // Part of public interface to class.
 
   /// removeDeadBindings - Scans the RegionStore of 'state' for dead values.
   ///  It returns a new Store with these values removed.
-  Store removeDeadBindings(Store store, const StackFrameContext *LCtx,
+  StoreRef removeDeadBindings(Store store, const StackFrameContext *LCtx,
                            SymbolReaper& SymReaper,
                           llvm::SmallVectorImpl<const MemRegion*>& RegionRoots);
 
-  Store enterStackFrame(const GRState *state, const StackFrameContext *frame);
+  StoreRef enterStackFrame(const GRState *state, const StackFrameContext *frame);
 
   //===------------------------------------------------------------------===//
   // Region "extents".
@@ -706,13 +716,13 @@ void invalidateRegionsWorker::VisitBaseRegion(const MemRegion *baseR) {
   B = RM.addBinding(B, baseR, BindingKey::Direct, V);
 }
 
-Store RegionStoreManager::invalidateRegions(Store store,
-                                            const MemRegion * const *I,
-                                            const MemRegion * const *E,
-                                            const Expr *Ex, unsigned Count,
-                                            InvalidatedSymbols *IS,
-                                            bool invalidateGlobals,
-                                            InvalidatedRegions *Regions) {
+StoreRef RegionStoreManager::invalidateRegions(Store store,
+                                               const MemRegion * const *I,
+                                               const MemRegion * const *E,
+                                               const Expr *Ex, unsigned Count,
+                                               InvalidatedSymbols *IS,
+                                               bool invalidateGlobals,
+                                               InvalidatedRegions *Regions) {
   invalidateRegionsWorker W(*this, StateMgr,
                             RegionStoreManager::GetRegionBindings(store),
                             Ex, Count, IS, Regions, invalidateGlobals);
@@ -745,7 +755,7 @@ Store RegionStoreManager::invalidateRegions(Store store,
       Regions->push_back(GS);
   }
 
-  return B.getRoot();
+  return StoreRef(B.getRootWithoutRetain(), *this);
 }
 
 //===----------------------------------------------------------------------===//
@@ -1252,17 +1262,19 @@ SVal RegionStoreManager::RetrieveArray(Store store, const TypedRegion * R) {
 // Binding values to regions.
 //===----------------------------------------------------------------------===//
 
-Store RegionStoreManager::Remove(Store store, Loc L) {
+StoreRef RegionStoreManager::Remove(Store store, Loc L) {
   if (isa<loc::MemRegionVal>(L))
     if (const MemRegion* R = cast<loc::MemRegionVal>(L).getRegion())
-      return removeBinding(GetRegionBindings(store), R).getRoot();
+      return StoreRef(removeBinding(GetRegionBindings(store),
+                                    R).getRootWithoutRetain(),
+                      *this);
 
-  return store;
+  return StoreRef(store, *this);
 }
 
-Store RegionStoreManager::Bind(Store store, Loc L, SVal V) {
+StoreRef RegionStoreManager::Bind(Store store, Loc L, SVal V) {
   if (isa<loc::ConcreteInt>(L))
-    return store;
+    return StoreRef(store, *this);
 
   // If we get here, the location should be a region.
   const MemRegion *R = cast<loc::MemRegionVal>(L).getRegion();
@@ -1301,11 +1313,12 @@ Store RegionStoreManager::Bind(Store store, Loc L, SVal V) {
 
   // Perform the binding.
   RegionBindings B = GetRegionBindings(store);
-  return addBinding(B, R, BindingKey::Direct, V).getRoot();
+  return StoreRef(addBinding(B, R, BindingKey::Direct,
+                             V).getRootWithoutRetain(), *this);
 }
 
-Store RegionStoreManager::BindDecl(Store store, const VarRegion *VR,
-                                   SVal InitVal) {
+StoreRef RegionStoreManager::BindDecl(Store store, const VarRegion *VR,
+                                      SVal InitVal) {
 
   QualType T = VR->getDecl()->getType();
 
@@ -1318,18 +1331,17 @@ Store RegionStoreManager::BindDecl(Store store, const VarRegion *VR,
 }
 
 // FIXME: this method should be merged into Bind().
-Store RegionStoreManager::BindCompoundLiteral(Store store,
-                                              const CompoundLiteralExpr *CL,
-                                              const LocationContext *LC,
-                                              SVal V) {
+StoreRef RegionStoreManager::BindCompoundLiteral(Store store,
+                                                 const CompoundLiteralExpr *CL,
+                                                 const LocationContext *LC,
+                                                 SVal V) {