1 files changed, 41 insertions, 33 deletions

diff --git a/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h b/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h
index 1052d9491a96..b112e66d30d3 100644
--- a/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h
+++ b/include/clang/StaticAnalyzer/Core/PathSensitive/ExplodedGraph.h
@@ -60,45 +60,50 @@ class ExplodedNode : public llvm::FoldingSetNode {
   friend class SwitchNodeBuilder;
   friend class EndOfFunctionNodeBuilder;
 
+  /// Efficiently stores a list of ExplodedNodes, or an optional flag.
+  ///
+  /// NodeGroup provides opaque storage for a list of ExplodedNodes, optimizing
+  /// for the case when there is only one node in the group. This is a fairly
+  /// common case in an ExplodedGraph, where most nodes have only one
+  /// predecessor and many have only one successor. It can also be used to
+  /// store a flag rather than a node list, which ExplodedNode uses to mark
+  /// whether a node is a sink. If the flag is set, the group is implicitly
+  /// empty and no nodes may be added.
   class NodeGroup {
-    enum { Size1 = 0x0, SizeOther = 0x1, AuxFlag = 0x2, Mask = 0x3 };
+    // Conceptually a discriminated union. If the low bit is set, the node is
+    // a sink. If the low bit is not set, the pointer refers to the storage
+    // for the nodes in the group.
+    // This is not a PointerIntPair in order to keep the storage type opaque.
     uintptr_t P;
-
-    unsigned getKind() const {
-      return P & 0x1;
-    }
-
-    void *getPtr() const {
-      assert (!getFlag());
-      return reinterpret_cast<void*>(P & ~Mask);
-    }
-
-    ExplodedNode *getNode() const {
-      return reinterpret_cast<ExplodedNode*>(getPtr());
-    }
     
   public:
-    NodeGroup() : P(0) {}
+    NodeGroup(bool Flag = false) : P(Flag) {
+      assert(getFlag() == Flag);
+    }
 
-    ExplodedNode **begin() const;
+    ExplodedNode * const *begin() const;
 
-    ExplodedNode **end() const;
+    ExplodedNode * const *end() const;
 
     unsigned size() const;
 
-    bool empty() const { return (P & ~Mask) == 0; }
+    bool empty() const { return P == 0 || getFlag() != 0; }
 
+    /// Adds a node to the list.
+    ///
+    /// The group must not have been created with its flag set.
     void addNode(ExplodedNode *N, ExplodedGraph &G);
 
+    /// Replaces the single node in this group with a new node.
+    ///
+    /// Note that this should only be used when you know the group was not
+    /// created with its flag set, and that the group is empty or contains
+    /// only a single node.
     void replaceNode(ExplodedNode *node);
 
-    void setFlag() {
-      assert(P == 0);
-      P = AuxFlag;
-    }
-
+    /// Returns whether this group was created with its flag set.
     bool getFlag() const {
-      return P & AuxFlag ? true : false;
+      return (P & 1);
     }
   };
 
@@ -119,9 +124,8 @@ public:
 
   explicit ExplodedNode(const ProgramPoint &loc, ProgramStateRef state,
                         bool IsSink)
-    : Location(loc), State(state) {
-    if (IsSink)
-      Succs.setFlag();
+    : Location(loc), State(state), Succs(IsSink) {
+    assert(isSink() == IsSink);
   }
   
   ~ExplodedNode() {}
@@ -190,9 +194,9 @@ public:
   }
 
   // Iterators over successor and predecessor vertices.
-  typedef ExplodedNode**       succ_iterator;
+  typedef ExplodedNode*       const *       succ_iterator;
   typedef const ExplodedNode* const * const_succ_iterator;
-  typedef ExplodedNode**       pred_iterator;
+  typedef ExplodedNode*       const *       pred_iterator;
   typedef const ExplodedNode* const * const_pred_iterator;
 
   pred_iterator pred_begin() { return Preds.begin(); }
@@ -278,11 +282,13 @@ protected:
   /// A list of nodes that can be reused.
   NodeVector FreeNodes;
   
-  /// A flag that indicates whether nodes should be recycled.
-  bool reclaimNodes;
+  /// Determines how often nodes are reclaimed.
+  ///
+  /// If this is 0, nodes will never be reclaimed.
+  unsigned ReclaimNodeInterval;
   
   /// Counter to determine when to reclaim nodes.
-  unsigned reclaimCounter;
+  unsigned ReclaimCounter;
 
 public:
 
@@ -370,7 +376,9 @@ public:
 
   /// Enable tracking of recently allocated nodes for potential reclamation
   /// when calling reclaimRecentlyAllocatedNodes().
-  void enableNodeReclamation() { reclaimNodes = true; }
+  void enableNodeReclamation(unsigned Interval) {
+    ReclaimCounter = ReclaimNodeInterval = Interval;
+  }
 
   /// Reclaim "uninteresting" nodes created since the last time this method
   /// was called.