add support for train_mode tune

ge/graph/passes/global_step_insert_pass.cc

@@ -28,6 +28,10 @@
 #include "graph/passes/pass_utils.h"
 #include "graph/ge_context.h"
 
+namespace {
+const char *const kFlagOff = "0";
+}  // namespace
+
 namespace ge {
 NodePtr GlobalStepInsertPass::InsertOp(ComputeGraphPtr &compute_graph,
                                        const string &node_type,
@@ -73,8 +77,9 @@ NodePtr GlobalStepInsertPass::InsertOp(ComputeGraphPtr &compute_graph,
 }
 
 Status GlobalStepInsertPass::Run(ComputeGraphPtr compute_graph) {
+  // run_flag off means offline, no need insert global step node which type is variable
   std::string run_flag;
-  if (ge::GetContext().GetOption(ge::RUN_FLAG, run_flag) == GRAPH_SUCCESS && run_flag == "0") {
+  if (ge::GetContext().GetOption(ge::RUN_FLAG, run_flag) == GRAPH_SUCCESS && run_flag == kFlagOff) {
     GELOGI("compute_graph [%u] [%s] skip insert global step", compute_graph->GetGraphID(),
            compute_graph->GetName().c_str());
     return SUCCESS;