1 files changed, 82 insertions, 0 deletions
diff --git a/src/armnn/optimizations/FoldPadIntoConvolution2d.hpp b/src/armnn/optimizations/FoldPadIntoConvolution2d.hpp
new file mode 100644
index 0000000000..f789ffae9a
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+++ b/src/armnn/optimizations/FoldPadIntoConvolution2d.hpp
@@ -0,0 +1,82 @@
+//
+// Copyright © 2017 Arm Ltd. All rights reserved.
+// SPDX-License-Identifier: MIT
+//
+
+#pragma once
+
+#include "Optimization.hpp"
+
+namespace armnn
+{
+namespace optimizations
+{
+
+class FoldPadIntoConvolution2dImpl
+{
+public:
+
+    void Run(Graph& graph, InputSlot& connection) const
+    {
+        Layer& base = connection.GetConnectedOutputSlot()->GetOwningLayer();
+        Layer& child = connection.GetOwningLayer();
+
+        BOOST_ASSERT(base.GetType() == LayerType::Pad);
+        BOOST_ASSERT(child.GetType() == LayerType::Convolution2d);
+
+        PadLayer* padLayer = boost::polymorphic_downcast<PadLayer*>(&base);
+        Convolution2dLayer* convolution2dLayer = boost::polymorphic_downcast<Convolution2dLayer*>(&child);
+
+        OutputSlot* parentOut = base.GetInputSlot(0).GetConnectedOutputSlot();
+        const TensorInfo& outInfo = child.GetOutputHandler().GetTensorInfo();
+
+        const std::string name = std::string("folded-") + base.GetName() + std::string("-into-") + child.GetName();
+        Convolution2dDescriptor descriptor = convolution2dLayer->GetParameters();
+
+        auto padList = padLayer->GetParameters().m_PadList;
+
+        armnn::DataLayout dataLayout = descriptor.m_DataLayout;
+
+        // In Convolution2dDescriptor, padLeft and padRight are defined as paddings on width dimension
+        // whereas padTop and padBottom - paddings on height dimension, so setting these according to data layout
+        if(dataLayout == armnn::DataLayout::NHWC)
+        {
+            descriptor.m_PadLeft = padList[2].first;
+            descriptor.m_PadRight = padList[2].second;
+            descriptor.m_PadTop = padList[1].first;
+            descriptor.m_PadBottom = padList[1].second;
+        }
+        else
+        {
+            descriptor.m_PadLeft = padList[3].first;
+            descriptor.m_PadRight = padList[3].second;
+            descriptor.m_PadTop = padList[2].first;
+            descriptor.m_PadBottom = padList[2].second;
+        }
+
+        auto& newConv2dLayer = *graph.InsertNewLayer<Convolution2dLayer>(base.GetInputSlot(0),
+                                                                         descriptor,
+                                                                         name.c_str());
+        newConv2dLayer.GetOutputHandler().SetTensorInfo(outInfo);
+
+        // Reconnects with original parent.
+        newConv2dLayer.GetOutputSlot().MoveAllConnections(*parentOut);
+        // Parent is now the new convolution2d layer.
+        parentOut = &newConv2dLayer.GetOutputSlot();
+
+        // Moves connections in child output to parent layer.
+        // Child layer will be removed as it's left unconnected.
+        // Base layer will be removed if left unconnected.
+        child.GetOutputSlot().MoveAllConnections(*parentOut);
+    }
+protected:
+    FoldPadIntoConvolution2dImpl() =  default;
+    ~FoldPadIntoConvolution2dImpl() = default;
+};
+
+using FoldPadIntoConvolution2d = OptimizeForConnection<PadLayer, Convolution2dLayer, FoldPadIntoConvolution2dImpl>;
+
+} // namespace optimizations
+} // namespace armnn
+
+