[LCG] Implement Tarjan's algorithm correctly this time. We have to walk

up the stack finishing the exploration of each entries children before
we're finished in addition to accounting for their low-links. Added
a unittest that really hammers home the need for this with interlocking
cycles that would each appear distinct otherwise and crash or compute
the wrong result. As part of this, nuke a stale fixme and bring the rest
of the implementation still more closely in line with the original
algorithm.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@206966 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 2 insertions, 1 deletions

diff --git a/include/llvm/Analysis/LazyCallGraph.h b/include/llvm/Analysis/LazyCallGraph.h
index cf74101c6e..aefad6f913 100644
--- a/include/llvm/Analysis/LazyCallGraph.h
+++ b/include/llvm/Analysis/LazyCallGraph.h
@@ -381,7 +381,8 @@ private:
   /// \brief Helper to form a new SCC out of the top of a DFSStack-like
   /// structure.
   SCC *formSCCFromDFSStack(
-      SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack);
+      SmallVectorImpl<std::pair<Node *, Node::iterator>> &DFSStack,
+      SmallVectorImpl<std::pair<Node *, Node::iterator>>::iterator SCCBegin);
 
   /// \brief Retrieve the next node in the post-order SCC walk of the call graph.
   SCC *getNextSCCInPostOrder();