Not add graph copy construction method. test=develop

paddle/fluid/framework/ir/graph.cc

@@ -14,7 +14,6 @@ limitations under the License. */
 
 #include <algorithm>
 #include <unordered_map>
-#include <unordered_set>
 
 #include "paddle/fluid/framework/ir/graph.h"
 #include "paddle/fluid/framework/op_proto_maker.h"
@@ -30,8 +29,6 @@ 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

@@ -72,7 +72,6 @@ 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

@@ -54,14 +54,13 @@ 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>)
       .def("get_double", &Graph::Get<double>)
       .def("get_string", &Graph::Get<std::string>)
-      .def("get_marked_nodes", &Graph::Get<std::unordered_set<const Node *>>)
+      .def("get_marked_nodes", &Graph::Get<std::unordered_set<const Node *>>,
+           return_value_policy::reference)
       .def("set", [](Graph &self, const std::string &attr_name,
                      int attr) { return self.Set(attr_name, new int(attr)); })
       .def("set",
@@ -105,7 +104,8 @@ void BindGraph(py::module *m) {
       .def("retrieve_node", &Graph::RetrieveNode,
            return_value_policy::reference)
       .def("resolve_hazard", &Graph::ResolveHazard)
-      .def("origin_program_desc", &Graph::OriginProgram);
+      .def("origin_program_desc", &Graph::OriginProgram,
+           return_value_policy::reference);
 }
 
 void BindNode(py::module *m) {

python/paddle/fluid/framework.py

@@ -2006,10 +2006,13 @@ class IrGraph(object):
         """
         Create a new and duplicated IrGraph.
 
+        Warns:
+            The method only clones the graph structure, not its attributes.
+
         Returns:
             IrGraph: A new and duplicated graph.
         """
-        g = core.Graph(self.graph)
+        g = core.Graph(self.graph.origin_program_desc())
         return IrGraph(g, self._for_test)
 
     def is_test(self):