!356 Bugfix: fix allreduce has duplicate input from one output anchor

From: @hugo1
Reviewed-by: @xchu42,@ji_chen
Signed-off-by: @ji_chen

ge/graph/optimize/mem_rw_conflict_optimize.cc

@@ -607,6 +607,30 @@ Status InsertIdentityAsNeeded(const NodePtr &node) {
   }
   return SUCCESS;
 }
+Status HandleAllreduceDuplicateInput(ComputeGraphPtr &compute_graph) {
+   for (const auto &node : compute_graph->GetDirectNode()) {
+     if (node->GetType() == HCOMALLREDUCE) {
+       std::set<OutDataAnchorPtr> pre_out_anchor_set;
+       for (const auto &in_data_anchor : node->GetAllInDataAnchors()) {
+         auto pre_out_anchor = in_data_anchor->GetPeerOutAnchor();
+         GE_CHECK_NOTNULL(pre_out_anchor);
+         if (pre_out_anchor_set.find(pre_out_anchor) == pre_out_anchor_set.end()) {
+           pre_out_anchor_set.emplace(pre_out_anchor);
+           continue;
+         }
+         // need insert identity
+         auto pre_node = pre_out_anchor->GetOwnerNode();
+         auto identity_node = CreateIdentityAfterSrcNode(*pre_node, pre_out_anchor->GetIdx());
+         GE_CHECK_NOTNULL(identity_node);
+         auto ret = GraphUtils::InsertNodeBetweenDataAnchors(pre_out_anchor, in_data_anchor, identity_node);
+         GE_CHK_STATUS_RET(ret, "Fail to insert identity.");
+         GELOGI("InsertNode %s between %s and %s successfully.", identity_node->GetName().c_str(),
+               pre_node->GetName().c_str(), node->GetName().c_str());
+       }
+     }
+   }
+   return SUCCESS;
+}
 }  // namespace
 
 namespace ge {
@@ -665,13 +689,14 @@ Status GraphOptimize::CheckRWConflict(ComputeGraphPtr &compute_graph, bool &has_
   return SUCCESS;
 }
 Status GraphOptimize::HandleMemoryRWConflict(ComputeGraphPtr &compute_graph) {
+  GE_DUMP(compute_graph, "BeforeHandleMemConflict");
   node_rwtype_map_.clear();
   auto sub_graph_vec = compute_graph->GetAllSubgraphs();
   if (sub_graph_vec.empty()) {
-    GELOGD("No sub graph here. Ignore memory conflict handle.");
-    return SUCCESS;
+    // only root graph, to handle allreduce servral input from one output anchor
+    return HandleAllreduceDuplicateInput(compute_graph);
   }
-  GE_DUMP(compute_graph, "BeforeHandleMemConflict");
+
   // 1.loop all subgraph, mark rw type from inside to outside
   Status ret = MarkRWTypeForAllSubgraph(sub_graph_vec);
   if (ret != SUCCESS) {