Concat Elimination and Self Concat Fusion pass (#2634)

* [WIP] First commit

* Remove some commented code

* Further changes

* Further changes

* Add method to remove patterns with just one concat

* Add tests

* Add more tests

* Fix fan out case

* refactor code

* refactor code

* Added NGRAPH_DEBUG statements

* Use INTERPRETER as backend instead of CPU...travis build failure

* clang

* minor edit

* add more checks in the tests

* Incorporate Bob's comment

* Removed some NGRAPH_DEBUG statements and incorporated Pruthvi's comment

* Incorporate Xiaoyu's comments

* some refactoring

src/ngraph/CMakeLists.txt

@@ -320,6 +320,8 @@ set (SRC
     pass/zero_dim_tensor_elimination.cpp
     pass/zero_dim_tensor_elimination.hpp
     pass/zero_dim_tensor_elimination.hpp
+    pass/concat_fusion.hpp
+    pass/concat_fusion.cpp
     pattern/matcher.cpp
     pattern/matcher.hpp
     pattern/op/any.hpp

src/ngraph/pass/concat_fusion.hpp

+//*****************************************************************************
+// Copyright 2017-2019 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/pass/graph_rewrite.hpp"
+#include "ngraph/pass/pass.hpp"
+#include "ngraph/pattern/matcher.hpp"
+#include "ngraph/pattern/op/label.hpp"
+
+namespace ngraph
+{
+    namespace pass
+    {
+        class ConcatElimination;
+        class SelfConcatFusion;
+    }
+}
+
+class ngraph::pass::ConcatElimination : public ngraph::pass::GraphRewrite
+{
+public:
+    ConcatElimination()
+        : GraphRewrite()
+    {
+        construct_concat_elimination();
+    }
+
+private:
+    void construct_concat_elimination();
+};
+
+class ngraph::pass::SelfConcatFusion : public ngraph::pass::FunctionPass
+{
+public:
+    virtual bool run_on_function(std::shared_ptr<ngraph::Function> function) override;
+
+private:
+    void update_concat_pattern_vectors(const std::shared_ptr<Node>&);
+    void remove_single_concat_op_pattern();
+    void construct_concat_patterns(const std::shared_ptr<pattern::Matcher>&,
+                                   const std::shared_ptr<pattern::op::Label>&,
+                                   const std::shared_ptr<Node>&);
+    bool replace_patterns(const NodeVector&);
+    std::vector<NodeVector> m_concat_pattern_vectors;
+};

test/CMakeLists.txt

@@ -33,6 +33,7 @@ set(SRC
     build_graph.cpp
     builder_autobroadcast.cpp
     constant_folding.cpp
+    concat_fusion.cpp
     control_dependencies.cpp
     coordinate.cpp
     copy.cpp