IVGCVSW-3277 Refactor TensorHandle factory API

 * Added backend support for multiple types of TensorHandle factories
 * Refactored the backend API to enable new tensor strategies
 * Added mechanism to determine memory strategies during optimization
 * Perform mem-copy only when Direct access is not found
 * Explicitly deleted the copy-constructor from OutputSlot to prevent
   accidental local copies that would cause the DisconnectAll to be
   called by the destructor

Change-Id: I7e812c8e5e6c1c20db1c5932749ac70fd93db7f8
Signed-off-by: Derek Lamberti <derek.lamberti@arm.com>
Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>

1 files changed, 40 insertions, 5 deletions

diff --git a/src/backends/backendsCommon/IBackendInternal.hpp b/src/backends/backendsCommon/IBackendInternal.hpp
index fe9d620278..a0d6569949 100644
--- a/src/backends/backendsCommon/IBackendInternal.hpp
+++ b/src/backends/backendsCommon/IBackendInternal.hpp
@@ -10,7 +10,11 @@
 
 #include <ISubgraphViewConverter.hpp>
 #include <SubgraphView.hpp>
+#include <optimizations/Optimization.hpp>
 
+#include "IBackendContext.hpp"
+#include "IMemoryManager.hpp"
+#include "ITensorHandleFactory.hpp"
 #include "OptimizationViews.hpp"
 
 #include <vector>
@@ -18,9 +22,7 @@
 namespace armnn
 {
 class IWorkloadFactory;
-class IBackendContext;
 class IMemoryManager;
-class Optimization;
 class ILayerSupport;
 
 class IBackendInternal : public IBackend
@@ -60,7 +62,10 @@ public:
     }
 
     ARMNN_DEPRECATED_MSG("Use \"OptimizationViews OptimizeSubgraphView(const SubgraphView&)\" instead")
-    virtual Optimizations GetOptimizations() const = 0;
+    virtual Optimizations GetOptimizations() const
+    {
+        return Optimizations{};
+    }
 
     ARMNN_DEPRECATED_MSG("Use \"OptimizationViews OptimizeSubgraphView(const SubgraphView&)\" instead")
     virtual SubGraphUniquePtr OptimizeSubGraph(const SubGraph& subGraph, bool& optimizationAttempted) const
@@ -70,12 +75,19 @@ public:
     }
     ARMNN_NO_DEPRECATE_WARN_END
 
-    virtual IMemoryManagerUniquePtr CreateMemoryManager() const = 0;
+
+    virtual IMemoryManagerUniquePtr CreateMemoryManager() const
+    {
+        return IMemoryManagerUniquePtr();
+    };
 
     virtual IWorkloadFactoryPtr CreateWorkloadFactory(
         const IMemoryManagerSharedPtr& memoryManager = nullptr) const = 0;
 
-    virtual IBackendContextPtr CreateBackendContext(const IRuntime::CreationOptions&) const = 0;
+    virtual IBackendContextPtr CreateBackendContext(const IRuntime::CreationOptions&) const
+    {
+        return IBackendContextPtr{};
+    }
 
     virtual ILayerSupportSharedPtr GetLayerSupport() const = 0;
 
@@ -107,6 +119,29 @@ public:
         }
         return result;
     }
+
+    bool SupportsTensorAllocatorAPI() const { return GetHandleFactoryPreferences().empty() == false; }
+
+    ITensorHandleFactory::FactoryId GetBackwardCompatibleFavoriteHandleFactory()
+    {
+        auto favorites = GetHandleFactoryPreferences();
+        if (favorites.empty())
+        {
+            return ITensorHandleFactory::LegacyFactoryId;
+        }
+        return favorites[0];
+    }
+
+    /// (Optional) Returns a vector of supported TensorHandleFactory ids in preference order.
+    virtual std::vector<ITensorHandleFactory::FactoryId> GetHandleFactoryPreferences() const
+    {
+        return std::vector<ITensorHandleFactory::FactoryId>();
+    }
+
+    /// (Optional) Register TensorHandleFactories
+    /// Either this method or CreateMemoryManager() and
+    /// IWorkloadFactory::CreateTensor()/IWorkloadFactory::CreateSubtensor() methods must be implemented.
+    virtual void RegisterTensorHandleFactories(class TensorHandleFactoryRegistry& registry) {}
 };
 
 using IBackendInternalUniquePtr = std::unique_ptr<IBackendInternal>;