Reapply r149311 which I reverted by mistake.

 Original log:

 Convert ProgramStateRef to a smart pointer for managing the reference counts of ProgramStates.  This leads to a slight memory
 improvement, and a simplification of the logic for managing ProgramState objects.
 # Please enter the commit message for your changes. Lines starting

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@149339 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 24 insertions, 22 deletions

diff --git a/lib/StaticAnalyzer/Core/Checker.cpp b/lib/StaticAnalyzer/Core/Checker.cpp
index f793c7fe29..07e0aac2d4 100644
--- a/lib/StaticAnalyzer/Core/Checker.cpp
+++ b/lib/StaticAnalyzer/Core/Checker.cpp
@@ -11,6 +11,7 @@
 //
 //===----------------------------------------------------------------------===//
 
+#include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
 #include "clang/StaticAnalyzer/Core/Checker.h"
 
 using namespace clang;
diff --git a/lib/StaticAnalyzer/Core/ExprEngine.cpp b/lib/StaticAnalyzer/Core/ExprEngine.cpp
index 2d047d2c46..5087ae1d33 100644
--- a/lib/StaticAnalyzer/Core/ExprEngine.cpp
+++ b/lib/StaticAnalyzer/Core/ExprEngine.cpp
@@ -238,13 +238,8 @@ static bool shouldRemoveDeadBindings(AnalysisManager &AMgr,
 
 void ExprEngine::ProcessStmt(const CFGStmt S,
                              ExplodedNode *Pred) {
-  // TODO: Use RAII to remove the unnecessary, tagged nodes.
-  //RegisterCreatedNodes registerCreatedNodes(getGraph());
-
   // Reclaim any unnecessary nodes in the ExplodedGraph.
   G.reclaimRecentlyAllocatedNodes();
-  // Recycle any unused states in the ProgramStateManager.
-  StateMgr.recycleUnusedStates();
   
   currentStmt = S.getStmt();
   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
@@ -1856,7 +1851,7 @@ struct DOTGraphTraits<ExplodedNode*> :
     }
 
     ProgramStateRef state = N->getState();
-    Out << "\\|StateID: " << (void*) state
+    Out << "\\|StateID: " << (void*) state.getPtr()
         << " NodeID: " << (void*) N << "\\|";
     state->printDOT(Out);
 
diff --git a/lib/StaticAnalyzer/Core/ProgramState.cpp b/lib/StaticAnalyzer/Core/ProgramState.cpp
index b8b9ad94df..459bf83ce5 100644
--- a/lib/StaticAnalyzer/Core/ProgramState.cpp
+++ b/lib/StaticAnalyzer/Core/ProgramState.cpp
@@ -25,6 +25,26 @@ using namespace ento;
 // FIXME: Move this elsewhere.
 ConstraintManager::~ConstraintManager() {}
 
+namespace clang { namespace  ento {
+/// Increments the number of times this state is referenced.
+
+void ProgramStateRetain(const ProgramState *state) {
+  ++const_cast<ProgramState*>(state)->refCount;
+}
+
+/// Decrement the number of times this state is referenced.
+void ProgramStateRelease(const ProgramState *state) {
+  assert(state->refCount > 0);
+  ProgramState *s = const_cast<ProgramState*>(state);
+  if (--s->refCount == 0) {
+    ProgramStateManager &Mgr = s->getStateManager();
+    Mgr.StateSet.RemoveNode(s);
+    s->~ProgramState();    
+    Mgr.freeStates.push_back(s);
+  }
+}
+}}
+
 ProgramState::ProgramState(ProgramStateManager *mgr, const Environment& env,
                  StoreRef st, GenericDataMap gdm)
   : stateMgr(mgr),
@@ -328,23 +348,10 @@ ProgramStateRef ProgramStateManager::getInitialState(const LocationContext *Init
   return getPersistentState(State);
 }
 
-void ProgramStateManager::recycleUnusedStates() {
-  for (std::vector<ProgramState*>::iterator i = recentlyAllocatedStates.begin(),
-       e = recentlyAllocatedStates.end(); i != e; ++i) {
-    ProgramState *state = *i;
-    if (state->referencedByExplodedNode())
-      continue;
-    StateSet.RemoveNode(state);
-    freeStates.push_back(state);
-    state->~ProgramState();
-  }
-  recentlyAllocatedStates.clear();
-}
-
 ProgramStateRef ProgramStateManager::getPersistentStateWithGDM(
                                                      ProgramStateRef FromState,
                                                      ProgramStateRef GDMState) {
-  ProgramState NewState = *FromState;
+  ProgramState NewState(*FromState);
   NewState.GDM = GDMState->GDM;
   return getPersistentState(NewState);
 }
@@ -368,12 +375,11 @@ ProgramStateRef ProgramStateManager::getPersistentState(ProgramState &State) {
   }
   new (newState) ProgramState(State);
   StateSet.InsertNode(newState, InsertPos);
-  recentlyAllocatedStates.push_back(newState);
   return newState;
 }
 
 ProgramStateRef ProgramState::makeWithStore(const StoreRef &store) const {
-  ProgramState NewSt = *this;
+  ProgramState NewSt(*this);
   NewSt.setStore(store);
   return getStateManager().getPersistentState(NewSt);
 }