IVGCVSW-3267 Add Arm NN front end support for the new Prelu Activation layer

 * Added new PreluLayer class
 * Made necessary changes to ILayerSupport, ILayerVisitor, etc.
 * Added unit tests

Change-Id: Ifcfb78e823bb5a245ed1dad15290d2f60115c882
Signed-off-by: Matteo Martincigh <matteo.martincigh@arm.com>

5 files changed, 27 insertions, 0 deletions

diff --git a/include/armnn/ILayerSupport.hpp b/include/armnn/ILayerSupport.hpp
index 4c113d3427..324a9f5a2d 100644
--- a/include/armnn/ILayerSupport.hpp
+++ b/include/armnn/ILayerSupport.hpp
@@ -234,6 +234,11 @@ public:
                                         const PreCompiledDescriptor& descriptor,
                                         Optional<std::string&> reasonIfUnsupported = EmptyOptional()) const = 0;
 
+    virtual bool IsPreluSupported(const TensorInfo& input,
+                                  const TensorInfo& alpha,
+                                  const TensorInfo& output,
+                                  Optional<std::string&> reasonIfUnsupported = EmptyOptional()) const = 0;
+
     virtual bool IsQuantizeSupported(const TensorInfo& input,
                                      const TensorInfo& output,
                                      Optional<std::string&> reasonIfUnsupported = EmptyOptional()) const = 0;
diff --git a/include/armnn/ILayerVisitor.hpp b/include/armnn/ILayerVisitor.hpp
index ab83dbfb05..9519c8b0c1 100644
--- a/include/armnn/ILayerVisitor.hpp
+++ b/include/armnn/ILayerVisitor.hpp
@@ -290,6 +290,12 @@ public:
                                      const Pooling2dDescriptor& pooling2dDescriptor,
                                      const char* name = nullptr) = 0;
 
+    /// Function that a PReLU activation layer should call back to when its Accept(ILayerVisitor&) function is invoked.
+    /// @param layer - pointer to the layer which is calling back to this visit function.
+    /// @param name - Optional name for the layer.
+    virtual void VisitPreluLayer(const IConnectableLayer* layer,
+                                 const char* name = nullptr) = 0;
+
     /// Function a quantize layer should call back to when its Accept(ILayerVisitor&) function is invoked.
     /// @param layer - pointer to the layer which is calling back to this visit function.
     /// @param name - Optional name for the layer.
diff --git a/include/armnn/INetwork.hpp b/include/armnn/INetwork.hpp
index e5ebbc4e44..cacca33caf 100644
--- a/include/armnn/INetwork.hpp
+++ b/include/armnn/INetwork.hpp
@@ -427,6 +427,11 @@ public:
     /// @return - Interface for configuring the layer.
     virtual IConnectableLayer* AddSwitchLayer(const char* name = nullptr) = 0;
 
+    /// Adds a PReLU layer to the network.
+    /// @param name - Optional name for the layer.
+    /// @return - Interface for configuring the layer.
+    virtual IConnectableLayer* AddPreluLayer(const char* name = nullptr) = 0;
+
     virtual void Accept(ILayerVisitor& visitor) const = 0;
 
 protected:
diff --git a/include/armnn/LayerSupport.hpp b/include/armnn/LayerSupport.hpp
index d58aa8731a..673193f330 100644
--- a/include/armnn/LayerSupport.hpp
+++ b/include/armnn/LayerSupport.hpp
@@ -282,6 +282,14 @@ bool IsPreCompiledSupported(const BackendId& backend,
                             size_t reasonIfUnsupportedMaxLength = 1024);
 
 /// Deprecated in favor of IBackend and ILayerSupport interfaces
+bool IsPreluSupported(const BackendId& backend,
+                      const TensorInfo& input,
+                      const TensorInfo& alpha,
+                      const TensorInfo& output,
+                      char* reasonIfUnsupported = nullptr,
+                      size_t reasonIfUnsupportedMaxLength = 1024);
+
+/// Deprecated in favor of IBackend and ILayerSupport interfaces
 bool IsPooling2dSupported(const BackendId& backend,
                           const TensorInfo& input,
                           const TensorInfo& output,
diff --git a/include/armnn/LayerVisitorBase.hpp b/include/armnn/LayerVisitorBase.hpp
index b4a2ac7870..48fc2bbb0b 100644
--- a/include/armnn/LayerVisitorBase.hpp
+++ b/include/armnn/LayerVisitorBase.hpp
@@ -151,6 +151,9 @@ public:
                              const Pooling2dDescriptor&,
                              const char*) override { DefaultPolicy::Apply(__func__); }
 
+    void VisitPreluLayer(const IConnectableLayer*,
+                         const char*) override { DefaultPolicy::Apply(__func__); }
+
     void VisitQuantizeLayer(const IConnectableLayer*,
                             const char*) override { DefaultPolicy::Apply(__func__); }