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, 57 insertions, 15 deletions

diff --git a/src/armnn/SubGraph.hpp b/src/armnn/SubGraph.hpp
index d22377daff..81166f1285 100644
--- a/src/armnn/SubGraph.hpp
+++ b/src/armnn/SubGraph.hpp
@@ -6,6 +6,7 @@
 #pragma once
 
 #include "Layer.hpp"
+#include "Graph.hpp"
 
 #include <vector>
 #include <list>
@@ -22,18 +23,46 @@ namespace armnn
 class SubGraph final
 {
 public:
-    using InputSlots = std::vector<InputSlot *>;
-    using OutputSlots = std::vector<OutputSlot *>;
+    using SubGraphPtr = std::unique_ptr<SubGraph>;
+    using InputSlots = std::vector<InputSlot*>;
+    using OutputSlots = std::vector<OutputSlot*>;
     using Layers = std::list<Layer*>;
+    using Iterator = Layers::iterator;
+    using ConstIterator = Layers::const_iterator;
 
-    SubGraph();
-    SubGraph(InputSlots && inputs,
-             OutputSlots && outputs,
-             Layers && layers);
+    /// Empty subgraphs are not allowed, they must at least have a parent graph.
+    SubGraph() = delete;
 
-    const InputSlots & GetInputSlots() const;
-    const OutputSlots & GetOutputSlots() const;
-    const Layers & GetLayers() const;
+    /// Constructs a sub-graph from the entire given graph.
+    SubGraph(Graph& graph);
+
+    /// Constructs a sub-graph with the given arguments and binds it to the specified parent graph.
+    SubGraph(Graph* parentGraph, InputSlots&& inputs, OutputSlots&& outputs, Layers&& layers);
+
+    /// Constructs a sub-graph with the given arguments and uses the specified sub-graph to get a reference
+    /// to the parent graph.
+    SubGraph(const SubGraph& referenceSubGraph, InputSlots&& inputs, OutputSlots&& outputs, Layers&& layers);
+
+    /// Copy-constructor.
+    SubGraph(const SubGraph& subGraph);
+
+    /// Move-constructor.
+    SubGraph(SubGraph&& subGraph);
+
+    /// Constructs a sub-graph with only the given layer and uses the specified sub-graph to get a reference
+    /// to the parent graph.
+    SubGraph(const SubGraph& referenceSubGraph, IConnectableLayer* layer);
+
+    /// Updates this sub-graph with the contents of the whole given graph.
+    void Update(Graph& graph);
+
+    /// Adds a new layer, of type LayerType, to the graph this sub-graph is a view of.
+    template <typename LayerT, typename... Args>
+    LayerT* AddLayer(Args&&... args) const;
+
+    const InputSlots& GetInputSlots() const;
+    const OutputSlots& GetOutputSlots() const;
+    const Layers& GetLayers() const;
 
     const InputSlot* GetInputSlot(unsigned int index) const;
     InputSlot* GetInputSlot(unsigned int index);
@@ -44,19 +73,32 @@ public:
     unsigned int GetNumInputSlots() const;
     unsigned int GetNumOutputSlots() const;
 
-    Layers::iterator begin();
-    Layers::iterator end();
+    Iterator begin();
+    Iterator end();
 
-    Layers::const_iterator begin() const;
-    Layers::const_iterator end() const;
+    ConstIterator begin() const;
+    ConstIterator end() const;
 
-    Layers::const_iterator cbegin() const;
-    Layers::const_iterator cend() const;
+    ConstIterator cbegin() const;
+    ConstIterator cend() const;
 
 private:
+    void CheckSubGraph();
+
     InputSlots m_InputSlots;
     OutputSlots m_OutputSlots;
     Layers m_Layers;
+
+    /// Pointer to the graph this sub-graph is a view of.
+    Graph* m_ParentGraph;
 };
 
+template <typename LayerT, typename... Args>
+LayerT* SubGraph::AddLayer(Args&&... args) const
+{
+    BOOST_ASSERT(m_ParentGraph);
+
+    return m_ParentGraph->AddLayer<LayerT>(args...);
+}
+
 } // namespace armnn