!9868 Fix pynative second order grad memory

From: @zjun3021
Reviewed-by: @kisnwang,@chujinjin
Signed-off-by: @chujinjin

mindspore/ccsrc/pipeline/pynative/pynative_execute.cc

@@ -1433,8 +1433,8 @@ std::string PynativeExecutor::GetCellId(const py::object &cell, const py::args &
 }
 
 bool PynativeExecutor::IsNotNestedGrad() const {
-  MS_LOG(DEBUG) << "Grad nested count is " << grad_count_;
-  return grad_count_ <= 1;
+  MS_LOG(DEBUG) << "Grad nested count is " << grad_order_;
+  return grad_order_ <= 1;
 }
 
 bool PynativeExecutor::IsTopGraph(const std::string &cell_id) {
@@ -1446,8 +1446,8 @@ bool PynativeExecutor::IsTopGraph(const std::string &cell_id) {
 }
 
 void PynativeExecutor::SubNestedGradCount() {
-  if (grad_count_ > 0) {
-    --grad_count_;
+  if (grad_order_ > 0) {
+    --grad_order_;
   }
 }
 
@@ -1828,7 +1828,7 @@ void PynativeExecutor::EndGraphByOutId(const py::object &cell, const std::string
 
 void PynativeExecutor::UpdateCellGraph(const std::string &cell_id, bool need_cloned, bool is_grad) {
   FuncGraphPtr tmp = curr_g_;
-  if (need_cloned) {
+  if (need_cloned && !IsNotNestedGrad()) {
     auto cloned_curr_g = BasicClone(curr_g_);
     graph_info_map_[cloned_curr_g] = graph_info_map_.at(curr_g_);
     tmp = cloned_curr_g;
@@ -2365,7 +2365,7 @@ void PynativeExecutor::Clean() {
 void PynativeExecutor::ClearRes() {
   MS_LOG(DEBUG) << "Clear all res";
   Clean();
-  grad_count_ = 0;
+  grad_order_ = 0;
   grad_flag_ = false;
   dynamic_cell_ = false;
   grad_is_running_ = false;

mindspore/ccsrc/pipeline/pynative/pynative_execute.h

@@ -147,7 +147,7 @@ class PynativeExecutor : public std::enable_shared_from_this<PynativeExecutor> {
   void PopGraphStack();
   FuncGraphPtr GetDfbuilder(const std::string &cell_id = "");
   ResourcePtr GetResource(const std::string &cell_id = "");
-  void AddNestedGradCount() { ++grad_count_; }
+  void AddNestedGradCount() { ++grad_order_; }
   void SubNestedGradCount();
   bool IsNotNestedGrad() const;
   bool IsTopGraph(const std::string &cell_id);
@@ -204,7 +204,7 @@ class PynativeExecutor : public std::enable_shared_from_this<PynativeExecutor> {
   static std::shared_ptr<PynativeExecutor> executor_;
   static std::mutex instance_lock_;
   static int64_t graph_id_;
-  int64_t grad_count_{0};
+  int64_t grad_order_{0};
   bool grad_flag_{false};
   bool dynamic_cell_{false};
   bool grad_is_running_{false};