add clone function for IrGraph. test=develop

paddle/fluid/framework/ir/graph.cc

@@ -13,6 +13,7 @@ See the License for the specific language governing permissions and
 limitations under the License. */
 
 #include <algorithm>
+#include <unordered_map>
 #include <unordered_set>
 
 #include "paddle/fluid/framework/ir/graph.h"
@@ -29,6 +30,8 @@ Graph::Graph(const ProgramDesc &program) : program_(program) {
   ResolveHazard(var_nodes);
 }
 
+Graph::Graph(const Graph &o) : Graph(o.program_) {}
+
 std::map<std::string, std::vector<ir::Node *>> Graph::InitFromProgram(
     const ProgramDesc &program) {
   VLOG(3) << "block in program:" << program_.Size();

paddle/fluid/framework/ir/graph.h

@@ -17,6 +17,7 @@ limitations under the License. */
 #include <map>
 #include <memory>
 #include <string>
+#include <unordered_set>
 #include <vector>
 
 #include "paddle/fluid/framework/ir/node.h"
@@ -71,6 +72,7 @@ namespace ir {
 class Graph {
  public:
   explicit Graph(const ProgramDesc &program);
+  Graph(const Graph &o);
 
   virtual ~Graph() {
     for (auto &attr : attrs_) {

paddle/fluid/pybind/ir.cc

@@ -54,6 +54,8 @@ void BindGraph(py::module *m) {
       "The graph is a Directed Acyclic Single Static Assignment Graph, see "
       "`paddle::ir::Graph` for details.")
       .def(py::init<const ProgramDesc &>())
+      .def("__init__",
+           [](Graph &self, const Graph &other) { new (&self) Graph(other); })
       .def("has", &Graph::Has)
       .def("get_int", &Graph::Get<int>)
       .def("get_float", &Graph::Get<float>)

python/paddle/fluid/contrib/slim/tests/test_graph.py

@@ -52,7 +52,7 @@ def residual_block(num):
 
 
 class TestGraph(unittest.TestCase):
-    def test_graph_functions(self):
+    def test_graph_functions(self, for_ci=True):
         main = fluid.Program()
         startup = fluid.Program()
         with fluid.program_guard(main, startup):
@@ -60,11 +60,20 @@ class TestGraph(unittest.TestCase):
             opt = fluid.optimizer.Adam(learning_rate=0.001)
             opt.minimize(loss)
         graph = IrGraph(core.Graph(main.desc), for_test=False)
+        backup_graph = graph.clone()
+        self.assertEqual(len(graph.all_nodes()), len(backup_graph.all_nodes()))
+
         marked_nodes = set()
         for op in graph.all_op_nodes():
             if op.name().find('conv2d') > -1:
                 marked_nodes.add(op)
+        if not for_ci:
             graph.draw('.', 'residual', marked_nodes)
+            backup_marked_nodes = set()
+            for op in backup_graph.all_op_nodes():
+                if op.name().find('conv2d') > -1:
+                    backup_marked_nodes.add(op)
+            backup_graph.draw('.', 'backup', backup_marked_nodes)
         self.assertFalse(graph.has_circle())
         self.assertEqual(graph.graph_num(), 1)
         nodes = graph.topology_sort()

python/paddle/fluid/framework.py

@@ -2002,6 +2002,16 @@ class IrGraph(object):
         self.graph = graph
         self._for_test = for_test
 
+    def clone(self):
+        """
+        Create a new and duplicated IrGraph.
+
+        Returns:
+            IrGraph: A new and duplicated graph.
+        """
+        g = core.Graph(self.graph)
+        return IrGraph(g, self._for_test)
+
     def is_test(self):
         """
         If the graph is used for testing, the function returns true. Otherwise, returns false.