IVGCVSW-2458 Refactor the Optimize function (Network.cpp) so that

subgraphs are optimized by the backends

 * Added a new method OptimizeSubGraph to the backend interface
 * Refactored the Optimize function so that the backend-specific
   optimization is performed by the backend itself (through the new
   OptimizeSubGraph interface method)
 * Added a new ApplyBackendOptimizations function to apply the new
   changes
 * Added some new convenient constructors to the SubGraph class
 * Added AddLayer method and a pointer to the parent graph to the
   SubGraph class
 * Updated the sub-graph unit tests to match the changes
 * Added SelectSubGraphs and ReplaceSubGraphConnections overloads
   that work with sub-graphs
 * Removed unused code and minor refactoring where necessary

Change-Id: I46181794c6a9e3b10558944f804e06a8f693a6d0

1 files changed, 18 insertions, 15 deletions

diff --git a/src/armnn/Graph.hpp b/src/armnn/Graph.hpp
index 8f93f56b4a..8046977411 100644
--- a/src/armnn/Graph.hpp
+++ b/src/armnn/Graph.hpp
@@ -6,7 +6,6 @@
 
 #include "LayersFwd.hpp"
 #include "IGraphObservable.hpp"
-#include "SubGraph.hpp"
 
 #include <armnn/Types.hpp>
 #include <armnn/TensorFwd.hpp>
@@ -25,21 +24,23 @@
 namespace armnn
 {
 
+class SubGraph;
+
 class Graph
 {
 public:
-    template <typename CVLayerT>
-    static CVLayerT* PtrCast(Layer* const layer)
+    template <typename LayerType>
+    static LayerType* PtrCast(Layer* const layer)
     {
-        return boost::polymorphic_downcast<CVLayerT*>(layer);
+        return boost::polymorphic_downcast<LayerType*>(layer);
     }
 
-    using LayersList = std::list<Layer*>;
-    using Iterator = LayersList::const_iterator; // Const so pointers in the list can't be modified externally.
-    using ConstIterator = boost::transform_iterator<decltype(&PtrCast<const Layer>), Iterator>;
+    using LayerList = std::list<Layer*>;
+    using Iterator = LayerList::const_iterator; // Const so pointers in the list can't be modified externally.
     using IteratorDifference = Iterator::difference_type;
 
-    using ConstIteratorInputs = boost::transform_iterator<decltype(&PtrCast<const InputLayer>), Iterator>;
+    using ConstIterator        = boost::transform_iterator<decltype(&PtrCast<const Layer>),       Iterator>;
+    using ConstIteratorInputs  = boost::transform_iterator<decltype(&PtrCast<const InputLayer>),  Iterator>;
     using ConstIteratorOutputs = boost::transform_iterator<decltype(&PtrCast<const OutputLayer>), Iterator>;
 
     /// Wrapper class returned by Graph::GetInputLayers()
@@ -49,13 +50,13 @@ public:
 
         ConstIteratorInputs begin() const
         {
-            return { m_Graph.m_Layers.begin(), &PtrCast<const InputLayer> };
+            return { m_Graph.m_Layers.begin(), &(PtrCast<const InputLayer>) };
         }
 
         ConstIteratorInputs end() const
         {
             return { std::next(m_Graph.m_Layers.begin(), static_cast<IteratorDifference>(m_Graph.GetNumInputs())),
-                     &PtrCast<const InputLayer> };
+                     &(PtrCast<const InputLayer>) };
         }
 
         const Graph& m_Graph;
@@ -69,12 +70,12 @@ public:
         ConstIteratorOutputs begin() const
         {
             return { std::prev(m_Graph.m_Layers.end(), static_cast<IteratorDifference>(m_Graph.GetNumOutputs())),
-                     &PtrCast<const OutputLayer> };
+                     &(PtrCast<const OutputLayer>) };
         }
 
         ConstIteratorOutputs end() const
         {
-            return { m_Graph.m_Layers.end(), &PtrCast<const OutputLayer> };
+            return { m_Graph.m_Layers.end(), &(PtrCast<const OutputLayer>) };
         }
 
         const Graph& m_Graph;
@@ -127,9 +128,9 @@ public:
     Iterator end() { return m_Layers.end(); }
 
     /// Returns const iterator pointing to the beginning of the list. Lowercase for range-based for loops.
-    ConstIterator begin() const { return {m_Layers.begin(), &PtrCast<const Layer>}; }
+    ConstIterator begin() const { return {m_Layers.begin(), &(PtrCast<const Layer>)}; }
     /// Returns const iterator pointing to the end of the list. Lowercase for range-based for loops.
-    ConstIterator end() const { return {m_Layers.end(), &PtrCast<const Layer>}; }
+    ConstIterator end() const { return {m_Layers.end(), &(PtrCast<const Layer>)}; }
 
     /// Returns const iterator pointing to the beginning of the list. Lowercase for range-based for loops.
     ConstIterator cbegin() const { return begin(); }
@@ -161,6 +162,7 @@ public:
     void AddCopyLayers();
 
     void SubstituteSubGraph(std::unique_ptr<SubGraph> subGraph, IConnectableLayer* substituteLayer);
+    void SubstituteSubGraph(std::unique_ptr<SubGraph> subGraph, const SubGraph& substituteSubGraph);
 
     void InferTensorInfos();
 
@@ -214,10 +216,11 @@ private:
     std::unordered_map<const Layer*, Iterator> m_PosInGraphMap;
 
     void ReplaceSubGraphConnections(const SubGraph& subGraph, IConnectableLayer* substituteLayer);
+    void ReplaceSubGraphConnections(const SubGraph& subGraph, const SubGraph& substituteSubGraph);
     void EraseSubGraphLayers(const SubGraph &subGraph);
 
     /// Mutable to allow sorting on const object.
-    mutable LayersList m_Layers;
+    mutable LayerList m_Layers;
     mutable bool m_LayersInOrder;
 
     std::map<const GraphEvent, std::list<IGraphObservable*>> m_Views;