!973 Enhance add_memcpy_async pass

Merge pull request !973 from huanghui/enhance-add-memcpy-async-pass

mindspore/ccsrc/pre_activate/ascend/enhancer/add_memcpy_async.cc

@@ -23,6 +23,12 @@
 namespace mindspore {
 namespace opt {
 namespace {
+bool InputIsParameterOrValueNode(const AnfNodePtr &node) {
+  MS_EXCEPTION_IF_NULL(node);
+  auto kernel_with_index = AnfAlgo::VisitKernel(node, 0);
+  return kernel_with_index.first->isa<Parameter>() || kernel_with_index.first->isa<ValueNode>();
+}
+
 const AnfNodePtr AddMemcpyAsyncIfInputIsUsedByOthers(const FuncGraphPtr &graph, const CNodePtr &node) {
   MS_EXCEPTION_IF_NULL(graph);
   MS_EXCEPTION_IF_NULL(node);
@@ -39,7 +45,8 @@ const AnfNodePtr AddMemcpyAsyncIfInputIsUsedByOthers(const FuncGraphPtr &graph,
     if (manager->node_users().find(input) == manager->node_users().end()) {
       MS_LOG(EXCEPTION) << "node has no output in manager";
     }
-    if (manager->node_users()[input].size() > 1) {
+    // when input is used by others or is a parameter or is a value node, insert a memcpy_async
+    if (manager->node_users()[input].size() > 1 || InputIsParameterOrValueNode(input)) {
       replace = true;
       new_inputs.push_back(CreateMemcpyAsyncOp(graph, input));
     } else {