!1226 Add reduce_scatter communication op fusion pass

Merge pull request !1226 from YuJianfeng/reduce_scatter

mindspore/ccsrc/pre_activate/ascend/ascend_backend_optimization.cc

@@ -287,6 +287,7 @@ void AscendBackendOptimization(const std::shared_ptr<session::KernelGraph> &kern
   auto other_pm = std::make_shared<PassManager>("other_pm");
   other_pm->AddPass(std::make_shared<AllReduceFusion>());
   other_pm->AddPass(std::make_shared<AllGatherFusion>());
+  other_pm->AddPass(std::make_shared<ReduceScatterFusion>());
   other_pm->AddPass(std::make_shared<BroadcastFusion>());
   other_pm->AddPass(std::make_shared<ParameterTransOpFusion>());
   other_pm->AddPass(std::make_shared<RefreshParameterFormat>());

mindspore/ccsrc/pre_activate/pass/communication_op_fusion.h

@@ -68,6 +68,13 @@ class BroadcastFusion : public CommunicationOpFusion {
   explicit BroadcastFusion(size_t groups = 1) : CommunicationOpFusion("broadcast_fusion", kBroadcastOpName, groups) {}
   ~BroadcastFusion() override = default;
 };
+
+class ReduceScatterFusion : public CommunicationOpFusion {
+ public:
+  explicit ReduceScatterFusion(size_t groups = 1)
+      : CommunicationOpFusion("reduce_scatter_fusion", kReduceScatterOpName, groups) {}
+  ~ReduceScatterFusion() override = default;
+};
 }  // namespace opt
 }  // namespace mindspore
 #endif  // MINDSPORE_CCSRC_PRE_ACTIVATE_PASS_COMMUNICATION_OP_FUSION_H_