reenable r101565, removing a problematic assertion.

CGSCC can delete nodes in regions of the callgraph that
have already been visited.  If new CG nodes are allocated
to the same pointer, we shouldn't abort, just handle it
correctly by assigning a new number.  This should restore
stability by removing invalidated pointers that *will* be
reused from the densemap in the iterator.

llvm-svn: 101628

llvm/include/llvm/ADT/SCCIterator.h

@@ -66,7 +66,7 @@ class scc_iterator
   std::vector<unsigned> MinVisitNumStack;
 
   // A single "visit" within the non-recursive DFS traversal.
-  void DFSVisitOne(NodeType* N) {
+  void DFSVisitOne(NodeType *N) {
     ++visitNum;                         // Global counter for the visit order
     nodeVisitNumbers[N] = visitNum;
     SCCNodeStack.push_back(N);
@@ -83,7 +83,7 @@ class scc_iterator
       // TOS has at least one more child so continue DFS
       NodeType *childN = *VisitStack.back().second++;
       if (!nodeVisitNumbers.count(childN)) {
-        // this node has never been seen
+        // this node has never been seen.
         DFSVisitOne(childN);
         continue;
       }
@@ -187,7 +187,6 @@ public:
   /// ReplaceNode - This informs the scc_iterator that the specified Old node
   /// has been deleted, and New is to be used in its place.
   void ReplaceNode(NodeType *Old, NodeType *New) {
-    assert(!nodeVisitNumbers.count(New) && "New already in scc_iterator?");
     assert(nodeVisitNumbers.count(Old) && "Old not in scc_iterator?");
     nodeVisitNumbers[New] = nodeVisitNumbers[Old];
     nodeVisitNumbers.erase(Old);

llvm/lib/Analysis/IPA/CallGraphSCCPass.cpp

@@ -420,10 +420,8 @@ void CallGraphSCC::ReplaceNode(CallGraphNode *Old, CallGraphNode *New) {
   
   // Update the active scc_iterator so that it doesn't contain dangling
   // pointers to the old CallGraphNode.
-#if 0
   scc_iterator<CallGraph*> *CGI = (scc_iterator<CallGraph*>*)Context;
   CGI->ReplaceNode(Old, New);
-#endif
 }