!3739 not eliminate memcpy when nexe node is graph output

Merge pull request !3739 from laiyongqiang/eliminate_memcpy_bug

mindspore/ccsrc/backend/optimizer/ascend/enhancer/getnext_memcpy_elimination.cc

@@ -56,12 +56,19 @@ const AnfNodePtr GetnextMemcpyElimination::Process(const FuncGraphPtr &graph, co
     return nullptr;
   }
 
-  // 3. next_node is not nop node and it has only one input which is memcpy's output
+  // 3. next_node is not nop node, not graph output and it has only one input which is memcpy's output
   for (auto &item : next_nodes) {
     auto next_node = item.first->cast<CNodePtr>();
     if (opt::IsNopNode(next_node)) {
       return nullptr;
     }
+
+    auto graph_outputs = AnfAlgo::GetAllOutput(graph->output(), {prim::kPrimTupleGetItem});
+    auto iter = std::find(graph_outputs.begin(), graph_outputs.end(), next_node);
+    if (iter != graph_outputs.end()) {
+      return nullptr;
+    }
+
     if (next_node->inputs().size() != 2) {
       MS_LOG(DEBUG) << "next node has more than one input";
       return nullptr;

tests/ut/cpp/python_input/gtest_input/pre_activate/getnext_memcpy_elimination_test.py

@@ -44,12 +44,14 @@ def test_getnext_memcpy_elimination(tag):
         res = get_next()
         res = memcpy_async_attr(res)
         res = cast(res)
+        res = add(res)
         return res
 
     @fns
     def after():
         res = get_next()
         res = cast(res)
+        res = add(res)
         return res
 
     return fns[tag]