Add StopGradient op to ngraph (#1067)

* add StopGradient op

* add StopGradient op src

* remove adjoints and add interpreter

* fix compile issue

* use nop_elimination and add unit-test

* update cmake

* update unit-tests

src/ngraph/CMakeLists.txt

@@ -93,6 +93,7 @@ set (SRC
     op/slice.cpp
     op/softmax.cpp
     op/sqrt.cpp
+    op/stop_gradient.cpp
     op/subtract.cpp
     op/sum.cpp
     op/tan.cpp

src/ngraph/ngraph.hpp

@@ -119,6 +119,7 @@
 #include "ngraph/op/slice.hpp"
 #include "ngraph/op/softmax.hpp"
 #include "ngraph/op/sqrt.hpp"
+#include "ngraph/op/stop_gradient.hpp"
 #include "ngraph/op/subtract.hpp"
 #include "ngraph/op/sum.hpp"
 #include "ngraph/op/tan.hpp"

src/ngraph/op/stop_gradient.cpp

+/*******************************************************************************
+* Copyright 2017-2018 Intel Corporation
+*
+* 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.
+*******************************************************************************/
+
+#include "ngraph/op/stop_gradient.hpp"
+#include "ngraph/op/broadcast.hpp"
+#include "ngraph/op/constant.hpp"
+
+using namespace std;
+using namespace ngraph;
+
+op::StopGradient::StopGradient(const shared_ptr<Node>& arg)
+    : UnaryElementwiseArithmetic("StopGradient", arg)
+{
+}
+
+shared_ptr<Node> op::StopGradient::copy_with_new_args(const NodeVector& new_args) const
+{
+    if (new_args.size() != 1)
+    {
+        throw ngraph_error("Incorrect number of new arguments");
+    }
+    return make_shared<StopGradient>(new_args.at(0));
+}

src/ngraph/op/stop_gradient.hpp

+/*******************************************************************************
+* Copyright 2017-2018 Intel Corporation
+*
+* 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 "ngraph/op/util/unary_elementwise_arithmetic.hpp"
+
+namespace ngraph
+{
+    namespace op
+    {
+        /// \brief create StopGrdient op
+        class StopGradient : public util::UnaryElementwiseArithmetic
+        {
+        public:
+            /// \brief Constructs StopGradient
+            ///
+            /// \param arg Node that produces the input tensor.
+            StopGradient(const std::shared_ptr<Node>& arg);
+
+            virtual std::shared_ptr<Node>
+                copy_with_new_args(const NodeVector& new_args) const override;
+        };
+    }
+}

src/ngraph/pass/nop_elimination.cpp

@@ -24,6 +24,7 @@
 #include "ngraph/op/convert.hpp"
 #include "ngraph/op/pad.hpp"
 #include "ngraph/op/slice.hpp"
+#include "ngraph/op/stop_gradient.hpp"
 #include "ngraph/op/sum.hpp"
 #include "ngraph/util.hpp"
 #include "nop_elimination.hpp"
@@ -87,12 +88,19 @@ HANDLER_DECL(eliminate_broadcast)
     return false;
 }
 
+HANDLER_DECL(eliminate_stop_gradient)
+{
+    ngraph::replace_node(node, node->get_argument(0));
+    return true;
+}
+
 static const std::unordered_map<std::type_index,
                                 std::function<bool(const std::shared_ptr<ngraph::Node>&)>>
     dispatcher{{TI(ngraph::op::Pad), &eliminate_pad},
                {TI(ngraph::op::Sum), &eliminate_sum},
                {TI(ngraph::op::Convert), &eliminate_convert},
                {TI(ngraph::op::Slice), &eliminate_slice},
+               {TI(ngraph::op::StopGradient), &eliminate_stop_gradient},
                {TI(ngraph::op::Broadcast), &eliminate_broadcast}};
 
 bool ngraph::pass::NopElimination::run_on_function(std::shared_ptr<ngraph::Function> function)

test/nop_elimination.cpp

@@ -100,3 +100,16 @@ TEST(nop_elimination, eliminate_broadcast)
 
     ASSERT_EQ(count_ops_of_type<op::Broadcast>(f), 0);
 }
+
+TEST(nop_elimination, eliminate_stop_gradient)
+{
+    Shape shape{};
+    auto A = make_shared<op::Parameter>(element::f32, shape);
+    auto f = make_shared<Function>(make_shared<op::StopGradient>(A), op::ParameterVector{A});
+
+    pass::Manager pass_manager;
+    pass_manager.register_pass<pass::NopElimination>();
+    pass_manager.run_passes(f);
+
+    ASSERT_EQ(count_ops_of_type<op::StopGradient>(f), 0);
+}