From 6d2eb3403f5ad4d3c7d489777bada3b71c0f520b Mon Sep 17 00:00:00 2001
From: Jan Eilers <jan.eilers@arm.com>
Date: Fri, 20 Aug 2021 16:42:58 +0100
Subject: IVGCVSW-6294 Detect and remove extraneous fp16 conversion layers

Signed-off-by: Jan Eilers <jan.eilers@arm.com>
Change-Id: I69a6ceda0d3e8d39947df71a2ad0d365ac7767d8
Signed-off-by: Finn Williams <Finn.Williams@arm.com>
---
 src/armnn/Network.cpp | 44 +++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 43 insertions(+), 1 deletion(-)

diff --git a/src/armnn/Network.cpp b/src/armnn/Network.cpp
index 42d7ae33ac..db7b4c9bb3 100644
--- a/src/armnn/Network.cpp
+++ b/src/armnn/Network.cpp
@@ -709,12 +709,54 @@ OptimizationResult AttemptBackendAssignment(BackendSettings& backendSettings,
                 && layer->GetType() != LayerType::ConvertFp32ToFp16
                 && layer->GetType() != LayerType::ConvertFp16ToFp32)
             {
+                auto ConstantLayerFromFp16ToFp32 = [](Layer& layer)
+                {
+                    if (layer.GetType() == LayerType::Constant)
+                    {
+                        ConstantLayer* constantLayer = PolymorphicDowncast<ConstantLayer*>(&layer);
+
+                        auto& info = constantLayer->m_LayerOutput->GetTensorInfo();
+
+                        if (info.GetDataType() == DataType::Float16)
+                        {
+                            std::vector<float> newValues(info.GetNumElements());
+
+                            armnnUtils::FloatingPointConverter::ConvertFloat16To32(
+                                    constantLayer->m_LayerOutput->GetConstTensor<Half>(),
+                                    info.GetNumElements(),
+                                    newValues.data());
+
+                            TensorInfo newInfo(info);
+                            newInfo.SetDataType(DataType::Float32);
+                            ConstTensor newInput(newInfo, newValues);
+                            constantLayer->m_LayerOutput.reset(new ScopedTensorHandle(newInput));
+
+                            layer.GetOutputSlot(0).SetTensorInfo(newInfo);
+                        }
+                    }
+                };
+
+                bool checkType = false;
+
+                for (auto inputSlot : layer->GetInputSlots())
+                {
+                    auto connectedOutputSlot = inputSlot.GetConnectedOutputSlot();
+                    if (connectedOutputSlot->GetOwningLayer().GetType() == LayerType::Constant)
+                    {
+                        if (connectedOutputSlot->GetNumConnections() == 1)
+                        {
+                            checkType = true;
+                            ConstantLayerFromFp16ToFp32(connectedOutputSlot->GetOwningLayer());
+                        }
+                    }
+                }
+
                 // Insert FP16 -> FP32 conversion layer before current layer
                 std::vector<ConvertFp16ToFp32Layer*> convertFp16ToFp32Layers;
                 if (dataTypeIn == DataType::Float16)
                 {
                     convertFp16ToFp32Layers =
-                        InsertConvertFp16ToFp32LayersBefore(graph, *layer);
+                            InsertConvertFp16ToFp32LayersBefore(graph, *layer, checkType);
                 }
 
                 // Insert FP32 -> FP16 conversion layer after current layer
-- 
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