fix RemoveIntermediateOut in fuse_elewise_add_act_pass while converting graph to program (#44593)

* fix RemoveNode in fuse_elewise_add_act_pass

* fix

* change pointer to share_ptr

* fix

* fix

* fix format

* fix

* fix graph_safe_remove_nodes

paddle/fluid/framework/ir/fuse_elewise_add_act_pass.cc

@@ -297,7 +297,18 @@ void FuseElewiseAddActPass::RemoveIntermediateOut(Graph *graph) const {
       }
     }
   }
-  GraphSafeRemoveNodes(graph, need_removed_nodes);
+  details::RemovedVars *saved_removed_nodes = new details::RemovedVars;
+  GraphSafeRemoveNodes(graph, need_removed_nodes, saved_removed_nodes);
+  if (!saved_removed_nodes->empty()) {
+    // TODO(pangyoki): If kRemovedVars exists, merge saved_removed_nodes into
+    // RemovedVars.
+    PADDLE_ENFORCE_EQ(graph->Has(details::kRemovedVars),
+                      false,
+                      platform::errors::PreconditionNotMet(
+                          "Removed nodes are only saved for "
+                          "fuse_elewise_add_act_pass in temporary."));
+    graph->Set(details::kRemovedVars, saved_removed_nodes);
+  }
 }
 
 void FuseElewiseAddActPass::ReLinkNodes(Graph *graph,

paddle/fluid/framework/ir/graph.h

@@ -45,6 +45,8 @@ namespace details {
 // This attr is not recommended, because the graph should not dependence
 // the program once it is built.
 constexpr char kStaleProgramOpDescs[] = "stale_program_op_descs";
+constexpr char kRemovedVars[] = "removed_vars";
+typedef std::unordered_set<std::shared_ptr<ir::Node>> RemovedVars;
 }  //  namespace details
 
 namespace ir {

paddle/fluid/framework/ir/graph_helper.cc

@@ -549,6 +549,18 @@ static void GetGraphOpDesc(const std::vector<Node *> &nodes,
   }
 }
 
+template <class T = Node *>
+static void GetGraphVarDesc(const Graph &graph,
+                            const std::unordered_set<T> &nodes,
+                            std::vector<proto::VarDesc> *vars) {
+  for (T node : nodes) {
+    if (node->IsVar() && node->Var() &&
+        node->GetVarNodeBlockId() == graph.GetBlockId()) {
+      vars->emplace_back(*node->Var()->Proto());
+    }
+  }
+}
+
 static void GraphToBlock(const Graph &graph,
                          proto::BlockDesc *block,
                          const SortKind *sort_kind) {
@@ -562,11 +574,11 @@ static void GraphToBlock(const Graph &graph,
   }
 
   std::vector<proto::VarDesc> vars_in_graph;
-  for (Node *node : graph.Nodes()) {
-    if (node->IsVar() && node->Var() &&
-        node->GetVarNodeBlockId() == graph.GetBlockId()) {
-      vars_in_graph.emplace_back(*node->Var()->Proto());
-    }
+  GetGraphVarDesc<Node *>(graph, graph.Nodes(), &vars_in_graph);
+  if (graph.Has(details::kRemovedVars)) {
+    auto &removed_vars = graph.Get<details::RemovedVars>(details::kRemovedVars);
+    GetGraphVarDesc<std::shared_ptr<ir::Node>>(
+        graph, removed_vars, &vars_in_graph);
   }
 
   // add vars_in_graph to blcok

paddle/fluid/framework/ir/graph_pattern_detector.cc

@@ -771,11 +771,19 @@ bool IsNthOutput(Node *var, Node *op, const std::string &argument, size_t nth) {
   return var->Name() == op->Op()->Output(argument)[nth];
 }
 
-void GraphSafeRemoveNodes(Graph *graph,
-                          const std::unordered_set<const Node *> &nodes) {
+void GraphSafeRemoveNodes(
+    Graph *graph,
+    const std::unordered_set<const Node *> &nodes,
+    std::unordered_set<std::shared_ptr<Node>> *saved_nodes) {
   for (auto *node : nodes) {
+    if (saved_nodes != nullptr) {
+      // prevent unique_ptr node from being released
+      saved_nodes->insert(
+          std::move(graph->RemoveNode(const_cast<Node *>(node))));
+    } else {
       graph->RemoveNode(const_cast<Node *>(node));
     }
+  }
 
   for (auto *node : graph->Nodes()) {
     for (auto it = node->inputs.begin(); it != node->inputs.end();) {

paddle/fluid/framework/ir/graph_pattern_detector.h

@@ -392,8 +392,10 @@ bool HasOutput(Node* op, const std::string& argument);
 bool IsNthOutput(Node* var, Node* op, const std::string& argument, size_t nth);
 
 // Graph safely remove some nodes, will automatically clean up the edges.
-void GraphSafeRemoveNodes(Graph* graph,
-                          const std::unordered_set<const Node*>& nodes);
+void GraphSafeRemoveNodes(
+    Graph* graph,
+    const std::unordered_set<const Node*>& nodes,
+    std::unordered_set<std::shared_ptr<Node>>* saved_nodes = nullptr);
 
 // Some pre-defined patterns those can be reused in multiple passes.
 // The related Fluid Layer or Op should be one pattern here for better re-usage

paddle/fluid/pybind/ir.cc

@@ -50,7 +50,10 @@ using pybind11::return_value_policy;
 namespace paddle {
 namespace pybind {
 void BindGraph(py::module *m) {
-  m->def("graph_safe_remove_nodes", GraphSafeRemoveNodes);
+  m->def("graph_safe_remove_nodes",
+         [](Graph *graph, const std::unordered_set<const Node *> &nodes) {
+           return GraphSafeRemoveNodes(graph, nodes);
+         });
   m->def("has_circle", HasCircle);
   m->def("graph_num", GraphNum);
   m->def(