Move ExplodedNode reclaimation out of ExprEngine and into CoreEngine. Also have it based on adding predecessors/successors, not node allocation. No measurable performance change.

llvm-svn: 150720

clang/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h

@@ -25,6 +25,7 @@
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/FoldingSet.h"
 #include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/DenseSet.h"
 #include "llvm/Support/Allocator.h"
 #include "llvm/ADT/OwningPtr.h"
 #include "llvm/ADT/GraphTraits.h"
@@ -240,6 +241,7 @@ public:
 class ExplodedGraph {
 protected:
   friend class CoreEngine;
+  friend class ExplodedNode;
 
   // Type definitions.
   typedef std::vector<ExplodedNode *> NodeVector;
@@ -265,16 +267,13 @@ protected:
   unsigned NumNodes;
   
   /// A list of recently allocated nodes that can potentially be recycled.
-  NodeVector ChangedNodes;
+  llvm::DenseSet<ExplodedNode*> ChangedNodes;
   
   /// A list of nodes that can be reused.
   NodeVector FreeNodes;
   
   /// A flag that indicates whether nodes should be recycled.
   bool reclaimNodes;
-  
-  /// Counter to determine when to reclaim nodes.
-  unsigned reclaimCounter;
 
 public:
 
@@ -361,12 +360,12 @@ public:
                     llvm::DenseMap<const void*, const void*> *InverseMap) const;
 
   /// Enable tracking of recently allocated nodes for potential reclamation
-  /// when calling reclaimRecentlyAllocatedNodes().
+  /// when calling reclaimChangedNodes().
   void enableNodeReclamation() { reclaimNodes = true; }
 
   /// Reclaim "uninteresting" nodes created since the last time this method
   /// was called.
-  void reclaimRecentlyAllocatedNodes();
+  void reclaimChangedNodes();
 
 private:
   bool shouldCollect(const ExplodedNode *node);

clang/lib/StaticAnalyzer/Core/CoreEngine.cpp

@@ -192,6 +192,7 @@ bool CoreEngine::ExecuteWorkList(const LocationContext *L, unsigned Steps,
       --Steps;
     }
 
+    getGraph().reclaimChangedNodes();
     const WorkListUnit& WU = WList->dequeue();
 
     // Set the current block counter.

clang/lib/StaticAnalyzer/Core/ExplodedGraph.cpp

@@ -45,10 +45,8 @@ void ExplodedNode::SetAuditor(ExplodedNode::Auditor* A) {
 // Cleanup.
 //===----------------------------------------------------------------------===//
 
-static const unsigned CounterTop = 1000;
-
 ExplodedGraph::ExplodedGraph()
-  : NumNodes(0), reclaimNodes(false), reclaimCounter(CounterTop) {}
+  : NumNodes(0), reclaimNodes(false) {}
 
 ExplodedGraph::~ExplodedGraph() {}
 
@@ -127,19 +125,12 @@ void ExplodedGraph::collectNode(ExplodedNode *node) {
   node->~ExplodedNode();  
 }
 
-void ExplodedGraph::reclaimRecentlyAllocatedNodes() {
+void ExplodedGraph::reclaimChangedNodes() {
   if (ChangedNodes.empty())
     return;
 
-  // Only periodically relcaim nodes so that we can build up a set of
-  // nodes that meet the reclamation criteria.  Freshly created nodes
-  // by definition have no successor, and thus cannot be reclaimed (see below).
-  assert(reclaimCounter > 0);
-  if (--reclaimCounter != 0)
-    return;
-  reclaimCounter = CounterTop;
-
-  for (NodeVector::iterator it = ChangedNodes.begin(), et = ChangedNodes.end();
+  for (llvm::DenseSet<ExplodedNode*>::iterator it =
+       ChangedNodes.begin(), et = ChangedNodes.end();
        it != et; ++it) {
     ExplodedNode *node = *it;
     if (shouldCollect(node))
@@ -160,6 +151,12 @@ void ExplodedNode::addPredecessor(ExplodedNode *V, ExplodedGraph &G) {
   assert (!V->isSink());
   Preds.addNode(V, G);
   V->Succs.addNode(this, G);
+  if (G.reclaimNodes) {
+    if (Succs.size() == 1 && Preds.size() == 1)
+      G.ChangedNodes.insert(this);
+    if (V->Succs.size() == 1 && V->Preds.size() == 1)
+      G.ChangedNodes.insert(V);
+  }  
 #ifndef NDEBUG
   if (NodeAuditor) NodeAuditor->AddEdge(V, this);
 #endif
@@ -256,9 +253,6 @@ ExplodedNode *ExplodedGraph::getNode(const ProgramPoint &L,
 
     new (V) NodeTy(L, State, IsSink);
 
-    if (reclaimNodes)
-      ChangedNodes.push_back(V);
-
     // Insert the node into the node set and return it.
     Nodes.InsertNode(V, InsertPos);
     ++NumNodes;

clang/lib/StaticAnalyzer/Core/ExprEngine.cpp

@@ -238,10 +238,7 @@ static bool shouldRemoveDeadBindings(AnalysisManager &AMgr,
 }
 
 void ExprEngine::ProcessStmt(const CFGStmt S,
-                             ExplodedNode *Pred) {
-  // Reclaim any unnecessary nodes in the ExplodedGraph.
-  G.reclaimRecentlyAllocatedNodes();
-  
+                             ExplodedNode *Pred) {  
   currentStmt = S.getStmt();
   PrettyStackTraceLoc CrashInfo(getContext().getSourceManager(),
                                 currentStmt->getLocStart(),