message: Ensure that the constant has a layout
diff: @@ -312,8 +312,7 @@ CreateSimpleWindowReduction(poplar::Graph &graph,
  }
  // Allocate the output tensor
  - TF_ASSIGN_OR_RETURN(out, AddTensor(graph, std::make_pair(inst,0),
  - output_shape, res));
  + TF_ASSIGN_OR_RETURN(out, AddTensor(graph, std::make_pair(inst,0), output_shape, res));
  poplar::Tensor out_flat = out.flatten();
  auto cs = graph.addComputeSet(inst->name());
  @@ -536,6 +535,7 @@ CreateSimpleSelectAndScatter(poplar::Graph &graph,
  xla::Shape partial_shape(output_shape);
  partial_shape.add_dimensions(overlap_count);
  LayoutUtil::ClearLayout(&partial_shape);
  + partial_shape.mutable_layout()->set_format(DENSE);
  Literal identity_literal = GetIdentityConstantLiteral(scatter_root);
  