Add the Clone method in Graph. test=develop

paddle/fluid/framework/ir/graph.cc

@@ -152,6 +152,39 @@ void Graph::ResolveHazard(
   }
 }
 
+std::shared_ptr<Graph> Graph::Clone() {
+  auto cloned_graph = std::make_shared<Graph>(this->program_);
+  cloned_graph->ReleaseNodes();
+  cloned_graph->num_node_created_ = 0;
+  std::unordered_map<ir::Node *, ir::Node *> origin_to_cloned;
+  for (auto *n : this->node_set_) {
+    ir::Node *cloned_node = nullptr;
+    if (n->IsCtrlVar()) {
+      cloned_node = cloned_graph->CreateControlDepVar();
+    } else if (!n->var_desc_ && !n->op_desc_) {  // empty node
+      cloned_node = cloned_graph->CreateEmptyNode(n->Name(), n->NodeType());
+    } else if (n->IsVar()) {
+      cloned_node = cloned_graph->CreateVarNode(n->Var());
+    } else if (n->IsOp()) {
+      cloned_node = cloned_graph->CreateOpNode(n->Op());
+    }
+    if (cloned_node) {
+      origin_to_cloned[n] = cloned_node;
+    } else {
+      PADDLE_THROW("The cloned node's type is not supported!");
+    }
+  }
+  for (auto *n : this->node_set_) {
+    for (auto it = n->inputs.begin(); it != n->inputs.end(); it++) {
+      origin_to_cloned[n]->inputs.push_back(origin_to_cloned[*it]);
+    }
+    for (auto it = n->outputs.begin(); it != n->outputs.end(); it++) {
+      origin_to_cloned[n]->outputs.push_back(origin_to_cloned[*it]);
+    }
+  }
+  return cloned_graph;
+}
+
 bool IsControlDepVar(const ir::Node &var) {
   return var.Name().find(ir::Node::kControlDepVarName) != std::string::npos;
 }

paddle/fluid/framework/ir/graph.h

@@ -213,6 +213,10 @@ class Graph {
   void ResolveHazard(
       const std::map<std::string, std::vector<ir::Node *>> &var_nodes);
 
+  // Create a new and duplicated graph.
+  // WARN: The method only clones the graph structure, not its attributes.
+  std::shared_ptr<Graph> Clone();
+
  private:
   std::map<std::string, std::vector<ir::Node *>> InitFromProgram(
       const ProgramDesc &program);

paddle/fluid/framework/ir/node.h

@@ -14,6 +14,7 @@ limitations under the License. */
 
 #pragma once
 
+#include <memory>
 #include <string>
 #include <typeindex>
 #include <typeinfo>

paddle/fluid/pybind/ir.cc

@@ -18,6 +18,7 @@
 #include <string>
 #include <unordered_map>
 #include <unordered_set>
+#include <utility>
 #include "paddle/fluid/framework/ir/graph.h"
 #include "paddle/fluid/framework/ir/graph_helper.h"
 #include "paddle/fluid/framework/ir/graph_pattern_detector.h"
@@ -54,6 +55,7 @@ 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("clone", &Graph::Clone)
       .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

@@ -60,20 +60,12 @@ 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()
@@ -83,6 +75,14 @@ class TestGraph(unittest.TestCase):
         nodes_num = len(graph.all_nodes())
         graph.safe_remove_nodes(marked_nodes)
         self.assertEqual(len(graph.all_nodes()), nodes_num - len(marked_nodes))
+        backup_graph = graph.clone()
+        self.assertEqual(len(graph.all_nodes()), len(backup_graph.all_nodes()))
+        if not for_ci:
+            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)
 
 
 if __name__ == '__main__':

python/paddle/fluid/framework.py

@@ -2012,7 +2012,7 @@ class IrGraph(object):
         Returns:
             IrGraph: A new and duplicated graph.
         """
-        g = core.Graph(self.graph.origin_program_desc())
+        g = self.graph.clone()
         return IrGraph(g, self._for_test)
 
     def is_test(self):