Support GetEvalOder call in MEL.

Source/ComputationNetworkLib/ComputationNetwork.h

@@ -258,13 +258,20 @@ public:
         m_evalOrders[rootNode] = nodes;
     }
 
+    bool EvalOrderExists(const ComputationNodeBasePtr& rootNode) const
+    {
+        return m_evalOrders.find(rootNode) != m_evalOrders.end();
+    }
+
     // get depth-first traversal order
     // TODO: This is currently not immutable because it gets patched w.r.t. recurrent loops. Ideally we don't patch. Need to review and verify that it is sufficient.
     const std::list<ComputationNodeBasePtr>& GetEvalOrder(const ComputationNodeBasePtr& rootNode) const
     {
         auto iter = m_evalOrders.find(rootNode);
         if (iter == m_evalOrders.end())
+        {
             LogicError("GetEvalOrder: Called without prior call to FormEvalOrder() for %ls %ls operation", rootNode->NodeName().c_str(), rootNode->OperationName().c_str());
+        }
         return iter->second;
     }
 

Source/ComputationNetworkLib/ComputationNetworkEditing.cpp

@@ -76,6 +76,9 @@ void ComputationNetwork::CopySubTree(const ComputationNetwork& fromNet,
 
     ComputationNodeBasePtr fromRoot = fromNet.GetNodeFromName(fromName);
 
+    if (!fromNet.EvalOrderExists(fromRoot))
+        const_cast<ComputationNetwork&>(fromNet).FormEvalOrder(fromRoot);
+
     for (const auto& fromNode : fromNet.GetEvalOrder(fromRoot)) // BUGBUG: This probably will fail because the precomputed eval orders are invalid at this point.
     {
         wstring fromNodeName = fromNode->NodeName();
@@ -353,6 +356,9 @@ void ComputationNetwork::SetLearnableNodesBelowLearningRateMultiplier(const floa
     else
     {
         // for calculating a specific node
+        if (!EvalOrderExists(rootNode))
+            const_cast<ComputationNetwork&>(*this).FormEvalOrder(rootNode);
+
         for (const auto& node : GetAllNodesForRoot(rootNode))
         {
             if (node->OperationName() == OperationNameOf(LearnableParameter))