IVGCVSW-3269 Add Serialization support for the new Prelu Activation layer

 * Adds serialization/deserialization support
 * Adds related unit test

Signed-off-by: Ellen Norris-Thompson <ellen.norris-thompson@arm.com>
Change-Id: I600322b03e51f443cbcd9262bb27e36e5fd95ae5

7 files changed, 85 insertions, 3 deletions

diff --git a/src/armnnDeserializer/Deserializer.cpp b/src/armnnDeserializer/Deserializer.cpp
index 68f3e8d566..b23ed97b4c 100644
--- a/src/armnnDeserializer/Deserializer.cpp
+++ b/src/armnnDeserializer/Deserializer.cpp
@@ -213,6 +213,7 @@ m_ParserFunctions(Layer_MAX+1, &Deserializer::ParseUnsupportedLayer)
     m_ParserFunctions[Layer_PadLayer]                    = &Deserializer::ParsePad;
     m_ParserFunctions[Layer_PermuteLayer]                = &Deserializer::ParsePermute;
     m_ParserFunctions[Layer_Pooling2dLayer]              = &Deserializer::ParsePooling2d;
+    m_ParserFunctions[Layer_PreluLayer]                  = &Deserializer::ParsePrelu;
     m_ParserFunctions[Layer_QuantizeLayer]               = &Deserializer::ParseQuantize;
     m_ParserFunctions[Layer_ReshapeLayer]                = &Deserializer::ParseReshape;
     m_ParserFunctions[Layer_ResizeBilinearLayer]         = &Deserializer::ParseResizeBilinear;
@@ -292,6 +293,8 @@ Deserializer::LayerBaseRawPtr Deserializer::GetBaseLayer(const GraphPtr& graphPt
             return graphPtr->layers()->Get(layerIndex)->layer_as_PermuteLayer()->base();
         case Layer::Layer_Pooling2dLayer:
             return graphPtr->layers()->Get(layerIndex)->layer_as_Pooling2dLayer()->base();
+        case Layer::Layer_PreluLayer:
+            return graphPtr->layers()->Get(layerIndex)->layer_as_PreluLayer()->base();
         case Layer::Layer_QuantizeLayer:
             return graphPtr->layers()->Get(layerIndex)->layer_as_QuantizeLayer()->base();
         case Layer::Layer_ReshapeLayer:
@@ -2194,4 +2197,24 @@ void Deserializer::ParseSwitch(GraphPtr graph, unsigned int layerIndex)
     RegisterOutputSlots(graph, layerIndex, layer);
 }
 
+void Deserializer::ParsePrelu(GraphPtr graph, unsigned int layerIndex)
+{
+    CHECK_LAYERS(graph, 0, layerIndex);
+    auto inputs = GetInputs(graph, layerIndex);
+    CHECK_LOCATION();
+    CHECK_VALID_SIZE(inputs.size(), 2);
+
+    auto outputs = GetOutputs(graph, layerIndex);
+    CHECK_VALID_SIZE(outputs.size(), 1);
+
+    auto layerName = GetLayerName(graph, layerIndex);
+    IConnectableLayer* layer = m_Network->AddPreluLayer(layerName.c_str());
+
+    armnn::TensorInfo outputTensorInfo = ToTensorInfo(outputs[0]);
+    layer->GetOutputSlot(0).SetTensorInfo(outputTensorInfo);
+
+    RegisterInputSlots(graph, layerIndex, layer);
+    RegisterOutputSlots(graph, layerIndex, layer);
+}
+
 } // namespace armnnDeserializer
diff --git a/src/armnnDeserializer/Deserializer.hpp b/src/armnnDeserializer/Deserializer.hpp
index 20ab8c2bba..bef13b1c08 100644
--- a/src/armnnDeserializer/Deserializer.hpp
+++ b/src/armnnDeserializer/Deserializer.hpp
@@ -103,6 +103,7 @@ private:
     void ParsePad(GraphPtr graph, unsigned int layerIndex);
     void ParsePermute(GraphPtr graph, unsigned int layerIndex);
     void ParsePooling2d(GraphPtr graph, unsigned int layerIndex);
+    void ParsePrelu(GraphPtr graph, unsigned int layerIndex);
     void ParseQuantize(GraphPtr graph, unsigned int layerIndex);
     void ParseReshape(GraphPtr graph, unsigned int layerIndex);
     void ParseResizeBilinear(GraphPtr graph, unsigned int layerIndex);
diff --git a/src/armnnDeserializer/DeserializerSupport.md b/src/armnnDeserializer/DeserializerSupport.md
index 94c26fc808..b64045903a 100644
--- a/src/armnnDeserializer/DeserializerSupport.md
+++ b/src/armnnDeserializer/DeserializerSupport.md
@@ -33,6 +33,7 @@ The Arm NN SDK Deserialize parser currently supports the following layers:
 * Pad
 * Permute
 * Pooling2d
+* Prelu
 * Quantize
 * Reshape
 * ResizeBilinear
diff --git a/src/armnnSerializer/ArmnnSchema.fbs b/src/armnnSerializer/ArmnnSchema.fbs
index 1204ad8f0f..db5672f948 100644
--- a/src/armnnSerializer/ArmnnSchema.fbs
+++ b/src/armnnSerializer/ArmnnSchema.fbs
@@ -122,7 +122,8 @@ enum LayerType : uint {
     Merge = 37,
     Switch = 38,
     Concat = 39,
-    SpaceToDepth = 40
+    SpaceToDepth = 40,
+    Prelu = 41
 }
 
 // Base layer table to be used as part of other layers
@@ -555,6 +556,10 @@ table SwitchLayer {
     base:LayerBase;
 }
 
+table PreluLayer {
+    base:LayerBase;
+}
+
 union Layer {
     ActivationLayer,
     AdditionLayer,
@@ -596,7 +601,8 @@ union Layer {
     MergeLayer,
     SwitchLayer,
     ConcatLayer,
-    SpaceToDepthLayer
+    SpaceToDepthLayer,
+    PreluLayer
 }
 
 table AnyLayer {
diff --git a/src/armnnSerializer/Serializer.cpp b/src/armnnSerializer/Serializer.cpp
index 012ed666f1..81231e4eba 100644
--- a/src/armnnSerializer/Serializer.cpp
+++ b/src/armnnSerializer/Serializer.cpp
@@ -712,7 +712,14 @@ void SerializerVisitor::VisitPooling2dLayer(const armnn::IConnectableLayer* laye
 void SerializerVisitor::VisitPreluLayer(const armnn::IConnectableLayer* layer,
                                         const char* name)
 {
-    throw UnimplementedException("SerializerVisitor::VisitPreluLayer not yet implemented");
+    // Create FlatBuffer BaseLayer
+    auto flatBufferPreluBaseLayer = CreateLayerBase(layer, serializer::LayerType::LayerType_Prelu);
+
+    // Create the FlatBuffer AdditionLayer
+    auto flatBufferPreluLayer = serializer::CreatePreluLayer(m_flatBufferBuilder, flatBufferPreluBaseLayer);
+
+    // Add the AnyLayer to the FlatBufferLayers
+    CreateAnyLayer(flatBufferPreluLayer.o, serializer::Layer::Layer_PreluLayer);
 }
 
 void SerializerVisitor::VisitQuantizeLayer(const armnn::IConnectableLayer *layer, const char *name)
diff --git a/src/armnnSerializer/SerializerSupport.md b/src/armnnSerializer/SerializerSupport.md
index 865cdf0610..e19eb32639 100644
--- a/src/armnnSerializer/SerializerSupport.md
+++ b/src/armnnSerializer/SerializerSupport.md
@@ -33,6 +33,7 @@ The Arm NN SDK Serializer currently supports the following layers:
 * Pad
 * Permute
 * Pooling2d
+* Prelu
 * Quantize
 * Reshape
 * ResizeBilinear
diff --git a/src/armnnSerializer/test/SerializerTests.cpp b/src/armnnSerializer/test/SerializerTests.cpp
index a757e16436..812a4780f4 100644
--- a/src/armnnSerializer/test/SerializerTests.cpp
+++ b/src/armnnSerializer/test/SerializerTests.cpp
@@ -1499,6 +1499,49 @@ BOOST_AUTO_TEST_CASE(SerializeMultiplication)
     deserializedNetwork->Accept(verifier);
 }
 
+BOOST_AUTO_TEST_CASE(SerializePrelu)
+{
+    class PreluLayerVerifier : public LayerVerifierBase
+    {
+    public:
+        PreluLayerVerifier(const std::string& layerName,
+                           const std::vector<armnn::TensorInfo>& inputInfos,
+                           const std::vector<armnn::TensorInfo>& outputInfos)
+            : LayerVerifierBase(layerName, inputInfos, outputInfos) {}
+
+        void VisitPreluLayer(const armnn::IConnectableLayer* layer, const char* name) override
+        {
+            VerifyNameAndConnections(layer, name);
+        }
+    };
+
+    const std::string layerName("prelu");
+
+    armnn::TensorInfo inputTensorInfo ({ 4, 1, 2 }, armnn::DataType::Float32);
+    armnn::TensorInfo alphaTensorInfo ({ 5, 4, 3, 1 }, armnn::DataType::Float32);
+    armnn::TensorInfo outputTensorInfo({ 5, 4, 3, 2 }, armnn::DataType::Float32);
+
+    armnn::INetworkPtr network = armnn::INetwork::Create();
+    armnn::IConnectableLayer* const inputLayer = network->AddInputLayer(0);
+    armnn::IConnectableLayer* const alphaLayer = network->AddInputLayer(1);
+    armnn::IConnectableLayer* const preluLayer = network->AddPreluLayer(layerName.c_str());
+    armnn::IConnectableLayer* const outputLayer = network->AddOutputLayer(0);
+
+    inputLayer->GetOutputSlot(0).Connect(preluLayer->GetInputSlot(0));
+    alphaLayer->GetOutputSlot(0).Connect(preluLayer->GetInputSlot(1));
+    preluLayer->GetOutputSlot(0).Connect(outputLayer->GetInputSlot(0));
+
+    inputLayer->GetOutputSlot(0).SetTensorInfo(inputTensorInfo);
+    alphaLayer->GetOutputSlot(0).SetTensorInfo(alphaTensorInfo);
+    preluLayer->GetOutputSlot(0).SetTensorInfo(outputTensorInfo);
+
+    armnn::INetworkPtr deserializedNetwork = DeserializeNetwork(SerializeNetwork(*network));
+    BOOST_CHECK(deserializedNetwork);
+
+    PreluLayerVerifier verifier(layerName, {inputTensorInfo, alphaTensorInfo}, {outputTensorInfo});
+    deserializedNetwork->Accept(verifier);
+}
+
 BOOST_AUTO_TEST_CASE(SerializeNormalization)
 {
     class NormalizationLayerVerifier : public LayerVerifierBase