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, 49 insertions, 0 deletions

diff --git a/src/backends/backendsCommon/ITensorHandleFactory.hpp b/src/backends/backendsCommon/ITensorHandleFactory.hpp
new file mode 100644
index 0000000000..7685061eb3
--- /dev/null
+++ b/src/backends/backendsCommon/ITensorHandleFactory.hpp
@@ -0,0 +1,49 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#pragma once
+
+#include <armnn/Types.hpp>
+#include <armnn/IRuntime.hpp>
+
+namespace armnn
+{
+
+class ITensorHandleFactory
+{
+public:
+    using FactoryId = std::string;
+    static const FactoryId LegacyFactoryId;   // Use the workload factory to create the tensor handle
+    static const FactoryId DeferredFactoryId; // Some TensorHandleFactory decisions are deferred to run-time
+
+    virtual ~ITensorHandleFactory() {}
+
+
+    virtual std::unique_ptr<ITensorHandle> CreateSubTensorHandle(ITensorHandle& parent,
+                                                                 TensorShape const& subTensorShape,
+                                                                 unsigned int const* subTensorOrigin) const = 0;
+
+    virtual std::unique_ptr<ITensorHandle> CreateTensorHandle(const TensorInfo& tensorInfo) const = 0;
+
+    virtual const FactoryId GetId() const = 0;
+
+    virtual bool SupportsSubTensors() const = 0;
+
+    virtual bool SupportsMapUnmap() const final { return true; }
+
+    virtual bool SupportsExport() const final { return false; }
+
+    virtual bool SupportsImport() const final { return false; }
+};
+
+enum class MemoryStrategy
+{
+    Undefined,
+    DirectCompatibility,    // Only allocate the tensorhandle using the assigned factory
+    CopyToTarget,           // Default + Insert MemCopy node before target
+    ExportToTarget,         // Default + Insert Import node
+};
+
+} //namespace armnn