[analyzer] Fix PR11282 - an assert in markAsSink

This is another fallout from the refactoring. We were
calling MarkAsSink on a cached out node.
(Fixes radar://10376675)

llvm-svn: 143516

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

@@ -393,7 +393,7 @@ public:
                     const CFGBlock *dstT, const CFGBlock *dstF)
   : NodeBuilder(SrcNode, DstSet, C), DstT(dstT), DstF(dstF),
     InFeasibleTrue(!DstT), InFeasibleFalse(!DstF) {
-    // The Banch node builder does not generate autotransitions.
+    // The branch node builder does not generate autotransitions.
     // If there are no successors it means that both branches are infeasible.
     takeNodes(SrcNode);
   }

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

@@ -389,6 +389,7 @@ public:
 
   void clear() { Impl.clear(); }
   void insert(const ExplodedNodeSet &S) {
+    assert(&S != this);
     if (empty())
       Impl = S.Impl;
     else

clang/lib/StaticAnalyzer/Core/CoreEngine.cpp

@@ -546,14 +546,17 @@ ExplodedNode* NodeBuilder::generateNodeImpl(const ProgramPoint &Loc,
   ExplodedNode *N = C.Eng.G->getNode(Loc, State, &IsNew);
   N->addPredecessor(FromN, *C.Eng.G);
   Frontier.erase(FromN);
+  assert(IsNew || N->isSink() == MarkAsSink);
+
+  if (!IsNew)
+    return 0;
 
   if (MarkAsSink)
     N->markAsSink();
-    
-  if (IsNew && !MarkAsSink)
+  else
     Frontier.Add(N);
 
-  return (IsNew ? N : 0);
+  return N;
 }
 
 StmtNodeBuilder::~StmtNodeBuilder() {

clang/test/Analysis/misc-ps.c

@@ -106,3 +106,17 @@ static int radar10367606(int t) {
   return 0;
 }
 
+/* Caching out on a sink node. */
+extern int fooR10376675();
+extern int* bazR10376675();
+extern int nR10376675;
+void barR10376675(int *x) {
+  int *pm;
+  if (nR10376675 * 2) {
+    int *pk  = bazR10376675();
+    pm = pk; //expected-warning {{never read}}
+  }
+  do {
+    *x = fooR10376675();
+  } while (0);
+}