Port PR 4156 and 4184 to master (#4219)

* Added FP32 to FP16 conversion transformation

* Update src/ngraph/pass/convert_fp32_to_fp16.cpp
Co-Authored-By: Robert Kimball <robert.kimball@intel.com>

* Update src/ngraph/pass/convert_fp32_to_fp16.hpp
Co-Authored-By: Robert Kimball <robert.kimball@intel.com>

* Added NGRAPH_API for fp32 to fp16 conversion
Co-authored-by: Scott Cyphers <diyessi@users.noreply.github.com>
Co-authored-by: Robert Kimball <robert.kimball@intel.com>

src/ngraph/CMakeLists.txt

@@ -496,6 +496,8 @@ set (SRC
     pass/constant_folding.cpp
     pass/constant_folding.hpp
     pass/constant_to_broadcast.cpp
+    pass/convert_fp32_to_fp16.hpp
+    pass/convert_fp32_to_fp16.cpp
     pass/core_fusion.cpp
     pass/core_fusion.hpp
     pass/cse.cpp

src/ngraph/pass/convert_fp32_to_fp16.cpp

+//*****************************************************************************
+// Copyright 2017-2020 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/pass/convert_fp32_to_fp16.hpp"
+#include "ngraph/graph_util.hpp"
+#include "ngraph/op/constant.hpp"
+
+using namespace std;
+using namespace ngraph;
+
+void pass::ConvertFP32ToFP16::convert_constants_precision()
+{
+    auto constant =
+        std::make_shared<ngraph::op::Constant>(element::f32, Shape{1}, std::vector<float>{0});
+
+    ngraph::graph_rewrite_callback callback = [](pattern::Matcher& m) {
+        auto constant = std::dynamic_pointer_cast<ngraph::op::Constant>(m.get_match_root());
+        if (!constant)
+        {
+            return false;
+        }
+
+        if (constant->get_element_type() == element::f32)
+        {
+            auto data = constant->get_vector<float>();
+            std::vector<ngraph::float16> new_data(data.size());
+            for (size_t i = 0; i < data.size(); ++i)
+            {
+                new_data[i] = ngraph::float16(data[i]);
+            }
+            auto new_const = std::make_shared<ngraph::op::Constant>(
+                element::f16, constant->get_shape(), new_data);
+            new_const->set_friendly_name(constant->get_friendly_name());
+            ngraph::replace_node(constant, new_const);
+            return true;
+        }
+        return false;
+    };
+
+    auto m = std::make_shared<ngraph::pattern::Matcher>(constant, "ConvertFP32ToFP16");
+    this->add_matcher(m, callback, PassProperty::CHANGE_DYNAMIC_STATE);
+}
+
+void pass::ConvertFP32ToFP16::convert_parameters_precision()
+{
+    auto constant = std::make_shared<ngraph::op::Parameter>(element::f32, Shape{1});
+
+    ngraph::graph_rewrite_callback callback = [](pattern::Matcher& m) {
+        auto parameter = std::dynamic_pointer_cast<ngraph::op::Parameter>(m.get_match_root());
+        if (parameter && parameter->get_element_type() == element::f32)
+        {
+            parameter->set_element_type(element::f16);
+            return true;
+        }
+        return false;
+    };
+
+    auto m = std::make_shared<ngraph::pattern::Matcher>(constant, "ConvertFP32ToFP16");
+    this->add_matcher(m, callback, PassProperty::CHANGE_DYNAMIC_STATE);
+}

src/ngraph/pass/convert_fp32_to_fp16.hpp

+//*****************************************************************************
+// Copyright 2017-2020 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>
+
+namespace ngraph
+{
+    namespace pass
+    {
+        class ConvertFP32ToFP16;
+
+    } // namespace pass
+} // namespace ngraph
+
+class NGRAPH_API ngraph::pass::ConvertFP32ToFP16 : public ngraph::pass::GraphRewrite
+{
+public:
+    ConvertFP32ToFP16()
+        : GraphRewrite()
+    {
+        convert_constants_precision();
+        convert_parameters_precision();
+    }
+
+private:
+    void convert_constants_precision();
+
+    void convert_parameters_precision();
+};