[NGraph] add increment op to ngraph engine (#16929)

* add increment op to ngraph engine

test=develop

* fix style errors

test=develop

paddle/fluid/operators/ngraph/ops/increment_op.h

+/*Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License. */
+
+#pragma once
+
+#include <memory>
+#include <string>
+#include <unordered_map>
+#include <vector>
+
+#include "ngraph/ngraph.hpp"
+#include "paddle/fluid/operators/ngraph/ops/elementwise_node.h"
+#include "paddle/fluid/platform/ngraph_helper.h"
+
+namespace paddle {
+namespace operators {
+namespace ngraphs {
+
+void BuildIncrementNode(
+    const std::shared_ptr<paddle::framework::OperatorBase>& op,
+    std::shared_ptr<
+        std::unordered_map<std::string, std::shared_ptr<ngraph::Node>>>
+        ngb_node_map) {
+  auto x = paddle::platform::GetInputNode(op, "X", ngb_node_map);
+  auto op_attrs = paddle::framework::AttrReader(op->Attrs());
+  float step = op_attrs.Get<float>("step");
+  auto step_op = std::make_shared<ngraph::op::Constant>(
+      x->get_element_type(), x->get_shape(), std::vector<float>{step});
+  std::shared_ptr<ngraph::Node> out =
+      std::make_shared<ngraph::op::Add>(x, step_op);
+  paddle::platform::SetOutputNode(op, "Out", out, ngb_node_map);
+}
+
+}  // namespace ngraphs
+}  // namespace operators
+}  // namespace paddle
+
+REGISTER_NG_OP(increment, BuildIncrementNode);

python/paddle/fluid/tests/unittests/ngraph/test_increment_ngraph_op.py

+#   Copyright (c) 2019 PaddlePaddle Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from __future__ import print_function
+
+import unittest
+import numpy as np
+from paddle.fluid.tests.unittests.op_test import OpTest
+
+
+class TestNGRAPHIncrementOp(OpTest):
+    def setUp(self):
+        self.op_type = "increment"
+        self.dtype = np.float32
+        self.init_dtype_type()
+        self.inputs = {'X': np.random.random(1).astype(self.dtype)}
+        self.attrs = {'step': 2.0}
+        self.outputs = {
+            'Out': self.inputs['X'] + self.dtype(self.attrs['step'])
+        }
+        self._cpu_only = True
+
+    def init_dtype_type(self):
+        pass
+
+    def test_check_output(self):
+        self.check_output()
+
+    def test_check_grad(self):
+        self.check_grad(['X'], 'Out')
+
+
+if __name__ == "__main__":
+    unittest.main()