Add lod in gather/scatter (#24613)

* add lod msg in gather and scatter_op, test=develop

paddle/fluid/operators/gather_op.cc

@@ -43,6 +43,7 @@ class GatherOp : public framework::OperatorWithKernel {
     framework::DDim output_dims(ctx->GetInputDim("X"));
     output_dims[0] = batch_size;
     ctx->SetOutputDim("Out", output_dims);
+    ctx->ShareLoD("X", /*->*/ "Out");
   }
 
  protected:

paddle/fluid/operators/scatter_op.cc

@@ -51,6 +51,7 @@ class ScatterOp : public framework::OperatorWithKernel {
                       platform::errors::InvalidArgument(
                           "Updates and Ids should have same batch-size."));
     ctx->SetOutputDim("Out", ref_dims);
+    ctx->ShareLoD("X", /*->*/ "Out");
   }
 
  protected: