Remove condition from allreduce op class (#561)

* Remove NGRAPH_DISTRIBUTED from allreduce op class
* Add allreduce doc

doc/sphinx/source/ops/allreduce.rst

+.. allreduce.rst:
+
+###
+AllReduce
+###
+
+.. code-block:: cpp
+
+   AllReduce // Collective operation
+
+
+Description
+===========
+
+Combines values from all processes or devices and distributes the result back
+to all processes or devices.
+
+
+Inputs
+------
+
++-----------------+-------------------------+--------------------------------+
+| Name            | Element Type            | Shape                          |
++=================+=========================+================================+
+| ``arg``         | ``element::f32``        | Any                            |
+|                 | ``element::f64``        |                                |
++-----------------+-------------------------+--------------------------------+
+
+
+Outputs
+-------
+
++-----------------+-------------------------+--------------------------------+
+| Name            | Element Type            | Shape                          |
++=================+=========================+================================+
+| ``output``      | ``element::f32``        | Same as ``arg``                |
+|                 | ``element::f64``        |                                |
++-----------------+-------------------------+--------------------------------+
+
+
+C++ Interface
+=============
+
+.. doxygenclass:: ngraph::op::AllReduce
+   :project: ngraph
+   :members:

doc/sphinx/source/ops/index.rst

@@ -52,6 +52,7 @@ Not currently a comprehensive list.
    abs.rst
    acos.rst
    add.rst
+   allreduce.rst
    asin.rst
    atan.rst
    avg_pool.rst

src/ngraph/CMakeLists.txt

@@ -34,6 +34,7 @@ set (SRC
     node.cpp
     ops/abs.cpp
     ops/add.cpp
+    ops/allreduce.cpp
     ops/avg_pool.cpp
     ops/batch_norm.cpp
     ops/broadcast.cpp
@@ -215,11 +216,6 @@ if(NGRAPH_DISTRIBUTED_ENABLE AND MPI_CXX_INCLUDE_PATH)
     include_directories(SYSTEM ${MPI_C_INCLUDE_PATH} ${MPI_CXX_INCLUDE_PATH})
     link_directories(${MPI_C_LIBRARIES} ${MPI_CXX_LIBRARIES})
 
-    # Add sources for distributed ngraph
-    # and all its dependencies
-    set(SRC ${SRC}
-        ops/allreduce.cpp
-    )
     set_property(SOURCE codegen/compiler.cpp APPEND PROPERTY COMPILE_DEFINITIONS
         "MPI_HEADER_PATH=\"${MPI_C_INCLUDE_PATH}\";")
 endif()

src/ngraph/ngraph.hpp

@@ -67,6 +67,7 @@
 #include "ngraph/ops/abs.hpp"
 #include "ngraph/ops/acos.hpp"
 #include "ngraph/ops/add.hpp"
+#include "ngraph/ops/allreduce.hpp"
 #include "ngraph/ops/asin.hpp"
 #include "ngraph/ops/atan.hpp"
 #include "ngraph/ops/avg_pool.hpp"
@@ -130,7 +131,3 @@
 #include "ngraph/shape.hpp"
 #include "ngraph/types/element_type.hpp"
 #include "ngraph/types/type.hpp"
-
-#ifdef NGRAPH_DISTRIBUTED
-#include "ngraph/ops/allreduce.hpp"
-#endif

src/ngraph/ops/allreduce.cpp

@@ -12,8 +12,6 @@
 // See the License for the specific language governing permissions and
 // ----------------------------------------------------------------------------
 
-#ifdef NGRAPH_DISTRIBUTED
-
 #include "ngraph/ops/allreduce.hpp"
 
 using namespace std;
@@ -31,5 +29,3 @@ op::AllReduce::AllReduce(const std::shared_ptr<Node>& arg)
         throw ngraph_error("Unsupported data type for AllReduce");
     }
 }
-
-#endif

src/ngraph/ops/allreduce.hpp

@@ -14,8 +14,6 @@
 
 #pragma once
 
-#ifdef NGRAPH_DISTRIBUTED
-
 #include <memory>
 #include "ngraph/ops/util/requires_tensor_view_args.hpp"
 
@@ -40,5 +38,3 @@ namespace ngraph
         };
     }
 }
-
-#endif

src/ngraph/serializer.cpp

@@ -19,6 +19,7 @@
 #include "ngraph/ops/abs.hpp"
 #include "ngraph/ops/acos.hpp"
 #include "ngraph/ops/add.hpp"
+#include "ngraph/ops/allreduce.hpp"
 #include "ngraph/ops/asin.hpp"
 #include "ngraph/ops/atan.hpp"
 #include "ngraph/ops/avg_pool.hpp"
@@ -77,10 +78,6 @@
 #include "ngraph/util.hpp"
 #include "nlohmann/json.hpp"
 
-#ifdef NGRAPH_DISTRIBUTED
-#include "ngraph/ops/allreduce.hpp"
-#endif
-
 using namespace ngraph;
 using namespace std;
 using json = nlohmann::json;
@@ -279,12 +276,10 @@ static shared_ptr<ngraph::Function>
         {
             node = make_shared<op::Add>(args[0], args[1]);
         }
-#ifdef NGRAPH_DISTRIBUTED
         else if (node_op == "AllReduce")
         {
             node = make_shared<op::AllReduce>(args[0]);
         }
-#endif
         else if (node_op == "Asin")
         {
             node = make_shared<op::Asin>(args[0]);