COMPMID-3083: Add graph support for PRelu

Change-Id: I48492f8c48b818b563bba1e0b48831ac5cdf1420
Signed-off-by: Georgios Pinitas <georgios.pinitas@arm.com>
Reviewed-on: https://review.mlplatform.org/c/ml/ComputeLibrary/+/2685
Comments-Addressed: Arm Jenkins <bsgcomp@arm.com>
Reviewed-by: Michele Di Giorgio <michele.digiorgio@arm.com>
Tested-by: Arm Jenkins <bsgcomp@arm.com>
diff --git a/arm_compute/graph/GraphBuilder.h b/arm_compute/graph/GraphBuilder.h
index 33c222d..23541c4 100644
--- a/arm_compute/graph/GraphBuilder.h
+++ b/arm_compute/graph/GraphBuilder.h
@@ -366,6 +366,16 @@
      * @return Node ID of the created node, EmptyNodeID in case of error
      */
     static NodeID add_pooling_node(Graph &g, NodeParams params, NodeIdxPair input, PoolingLayerInfo pool_info);
+    /** Adds a prelu layer node to the graph
+     *
+     * @param[in] g      Graph to add the node to
+     * @param[in] params Common node parameters
+     * @param[in] input  Input to the PRelu node as a NodeID-Index pair
+     * @param[in] alpha  Alpha input to the PRelu node as a NodeID-Index pair
+     *
+     * @return Node ID of the created node, EmptyNodeID in case of error
+     */
+    static NodeID add_prelu_node(Graph &g, NodeParams params, NodeIdxPair input, NodeIdxPair alpha);
     /** Adds a print layer node to the graph
      *
      * @param[in] g           Graph to add the node to
diff --git a/arm_compute/graph/INodeVisitor.h b/arm_compute/graph/INodeVisitor.h
index 25018d4..deaa8f1 100644
--- a/arm_compute/graph/INodeVisitor.h
+++ b/arm_compute/graph/INodeVisitor.h
@@ -131,6 +131,11 @@
      * @param[in] n Node to visit.
      */
     virtual void visit(PermuteLayerNode &n) = 0;
+    /** Visit PreluLayerNode.
+     *
+     * @param[in] n Node to visit.
+     */
+    virtual void visit(PReluLayerNode &n) = 0;
     /** Visit PoolingLayerNode.
      *
      * @param[in] n Node to visit.
@@ -266,6 +271,10 @@
     {
         default_visit();
     }
+    virtual void visit(PReluLayerNode &) override
+    {
+        default_visit();
+    }
     virtual void visit(PrintLayerNode &) override
     {
         default_visit();
diff --git a/arm_compute/graph/TypePrinter.h b/arm_compute/graph/TypePrinter.h
index 7072b55..d56407b 100644
--- a/arm_compute/graph/TypePrinter.h
+++ b/arm_compute/graph/TypePrinter.h
@@ -128,6 +128,9 @@
         case NodeType::PoolingLayer:
             os << "PoolingLayer";
             break;
+        case NodeType::PReluLayer:
+            os << "PReluLayer";
+            break;
         case NodeType::PrintLayer:
             os << "PrintLayer";
             break;
diff --git a/arm_compute/graph/Types.h b/arm_compute/graph/Types.h
index 6a488d1..7c81641 100644
--- a/arm_compute/graph/Types.h
+++ b/arm_compute/graph/Types.h
@@ -153,6 +153,7 @@
     PadLayer,
     PermuteLayer,
     PoolingLayer,
+    PReluLayer,
     PrintLayer,
     PriorBoxLayer,
     QuantizationLayer,
diff --git a/arm_compute/graph/backends/FunctionHelpers.h b/arm_compute/graph/backends/FunctionHelpers.h
index 65a3e15..9f352ed 100644
--- a/arm_compute/graph/backends/FunctionHelpers.h
+++ b/arm_compute/graph/backends/FunctionHelpers.h
@@ -1149,6 +1149,44 @@
     return std::move(func);
 }
 
+/** Create a backend PRelu layer function
+ *
+ * @tparam PReluFunction Backend PRelu function
+ * @tparam TargetInfo    Target-specific information
+ *
+ * @param[in] node Node to create the backend function for
+ *
+ * @return Backend PRelu layer function
+ */
+template <typename PReluFunction, typename TargetInfo>
+std::unique_ptr<IFunction> create_prelu_layer(PReluLayerNode &node)
+{
+    validate_node<TargetInfo>(node, 2 /* expected inputs */, 1 /* expected outputs */);
+
+    // Extract IO and info
+    typename TargetInfo::TensorType *input  = get_backing_tensor<TargetInfo>(node.input(0));
+    typename TargetInfo::TensorType *alpha  = get_backing_tensor<TargetInfo>(node.input(1));
+    typename TargetInfo::TensorType *output = get_backing_tensor<TargetInfo>(node.output(0));
+    ARM_COMPUTE_ERROR_ON(input == nullptr || alpha == nullptr);
+    ARM_COMPUTE_ERROR_ON(output == nullptr);
+
+    // Create and configure function
+    auto func = support::cpp14::make_unique<PReluFunction>();
+    func->configure(input, alpha, output);
+
+    // Log info
+    ARM_COMPUTE_LOG_GRAPH_INFO("Instantiated "
+                               << node.name()
+                               << " Type: " << node.type()
+                               << " Target: " << TargetInfo::TargetType
+                               << " Data Type: " << input->info()->data_type()
+                               << " Input shape: " << input->info()->tensor_shape()
+                               << " Output shape: " << output->info()->tensor_shape()
+                               << std::endl);
+
+    return std::move(func);
+}
+
 /** Create a backend print layer function
  *
  * @tparam TargetInfo Target-specific information
diff --git a/arm_compute/graph/backends/ValidateHelpers.h b/arm_compute/graph/backends/ValidateHelpers.h
index 66de7ad..673caf9 100644
--- a/arm_compute/graph/backends/ValidateHelpers.h
+++ b/arm_compute/graph/backends/ValidateHelpers.h
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2018-2019 ARM Limited.
+ * Copyright (c) 2018-2020 ARM Limited.
  *
  * SPDX-License-Identifier: MIT
  *
@@ -369,6 +369,30 @@
 
     return PermuteLayer::validate(input, output, perm);
 }
+
+/** Validates a PRelu layer node
+ *
+ * @tparam PReluLayer PRelu layer type
+ *
+ * @param[in] node Node to validate
+ *
+ * @return Status
+ */
+template <typename PReluLayer>
+Status validate_prelu_layer(PReluLayerNode &node)
+{
+    ARM_COMPUTE_LOG_GRAPH_VERBOSE("Validating PRelu node with ID : " << node.id() << " and Name: " << node.name() << std::endl);
+    ARM_COMPUTE_RETURN_ERROR_ON(node.num_inputs() != 2);
+    ARM_COMPUTE_RETURN_ERROR_ON(node.num_outputs() != 1);
+
+    // Extract IO and info
+    arm_compute::ITensorInfo *input  = get_backing_tensor_info(node.input(0));
+    arm_compute::ITensorInfo *alpha  = get_backing_tensor_info(node.input(1));
+    arm_compute::ITensorInfo *output = get_backing_tensor_info(node.output(0));
+
+    return PReluLayer::validate(input, alpha, output);
+}
+
 /** Validates a priorbox layer node
  *
  * @tparam PriorBoxLayer PriorBox layer type
diff --git a/arm_compute/graph/frontend/Layers.h b/arm_compute/graph/frontend/Layers.h
index 2b44d0e..420f715 100644
--- a/arm_compute/graph/frontend/Layers.h
+++ b/arm_compute/graph/frontend/Layers.h
@@ -902,6 +902,34 @@
     PoolingLayerInfo _pool_info;
 };
 
+/** PRelu Layer */
+class PReluLayer final : public ILayer
+{
+public:
+    /** Construct an PRelu operation layer
+     *
+     * @param[in] sub_stream0 First graph sub-stream
+     * @param[in] sub_stream1 First graph sub-stream
+     */
+    PReluLayer(SubStream &&sub_stream0, SubStream &&sub_stream1)
+        : _ss0(std::move(sub_stream0)), _ss1(std::move(sub_stream1))
+    {
+    }
+
+    NodeID create_layer(IStream &s) override
+    {
+        NodeParams  common_params = { name(), s.hints().target_hint };
+        NodeIdxPair input         = { _ss0.tail_node(), 0 };
+        NodeIdxPair alpha         = { _ss1.tail_node(), 0 };
+
+        return GraphBuilder::add_prelu_node(s.graph(), common_params, input, alpha);
+    }
+
+private:
+    SubStream _ss0;
+    SubStream _ss1;
+};
+
 /** Print Layer */
 class PrintLayer final : public ILayer
 {
diff --git a/arm_compute/graph/nodes/Nodes.h b/arm_compute/graph/nodes/Nodes.h
index 37cc9e4..e8852d2 100644
--- a/arm_compute/graph/nodes/Nodes.h
+++ b/arm_compute/graph/nodes/Nodes.h
@@ -47,6 +47,7 @@
 #include "arm_compute/graph/nodes/NormalizationLayerNode.h"
 #include "arm_compute/graph/nodes/NormalizePlanarYUVLayerNode.h"
 #include "arm_compute/graph/nodes/OutputNode.h"
+#include "arm_compute/graph/nodes/PReluLayerNode.h"
 #include "arm_compute/graph/nodes/PadLayerNode.h"
 #include "arm_compute/graph/nodes/PermuteLayerNode.h"
 #include "arm_compute/graph/nodes/PoolingLayerNode.h"
diff --git a/arm_compute/graph/nodes/NodesFwd.h b/arm_compute/graph/nodes/NodesFwd.h
index 0fe86b0..0ccf243 100644
--- a/arm_compute/graph/nodes/NodesFwd.h
+++ b/arm_compute/graph/nodes/NodesFwd.h
@@ -56,6 +56,7 @@
 class PadLayerNode;
 class PermuteLayerNode;
 class PoolingLayerNode;
+class PReluLayerNode;
 class PrintLayerNode;
 class PriorBoxLayerNode;
 class QuantizationLayerNode;
diff --git a/arm_compute/graph/nodes/PReluLayerNode.h b/arm_compute/graph/nodes/PReluLayerNode.h
new file mode 100644
index 0000000..f2055c2
--- /dev/null
+++ b/arm_compute/graph/nodes/PReluLayerNode.h
@@ -0,0 +1,48 @@
+/*
+ * Copyright (c) 2020 ARM Limited.
+ *
+ * SPDX-License-Identifier: MIT
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+#ifndef ARM_COMPUTE_GRAPH_PRELU_LAYER_NODE_H
+#define ARM_COMPUTE_GRAPH_PRELU_LAYER_NODE_H
+
+#include "arm_compute/graph/INode.h"
+
+namespace arm_compute
+{
+namespace graph
+{
+/** PRelu Layer node */
+class PReluLayerNode final : public INode
+{
+public:
+    /** Default Constructor */
+    PReluLayerNode();
+
+    // Inherited overridden methods:
+    NodeType         type() const override;
+    bool             forward_descriptors() override;
+    TensorDescriptor configure_output(size_t idx) const override;
+    void accept(INodeVisitor &v) override;
+};
+} // namespace graph
+} // namespace arm_compute
+#endif /* ARM_COMPUTE_GRAPH_PRELU_LAYER_NODE_H */