message: Use new poplar API with ArrayRefs
diff: @@ -469,7 +469,9 @@ SetInitialTensorValue(poplar::Graph &graph,
  poplar::Tensor &tensor,
  const xla::Literal &literal) {
  const TYPE* data(static_cast<const TYPE*>(literal.untyped_data()));
  - graph.setInitialValue<TYPE>(tensor, data);
  + size_t element_count = literal.element_count();
  + poplar::ArrayRef<TYPE> array(data, element_count);
  + graph.setInitialValue<TYPE>(tensor, array);
  }
  static void
  @@ -477,20 +479,23 @@ SetFp16InitialTensorValue(poplar::Graph &graph,
  poplar::Tensor &tensor,
  const xla::Literal &literal) {
  const uint16_t* data(static_cast<const uint16_t*>(literal.untyped_data()));
  - graph.setInitialValueHalf(tensor, data);
  + size_t element_count = literal.element_count();
  + poplar::ArrayRef<uint16_t> array(data, element_count);
  + graph.setInitialValueHalf(tensor, array);
  }
  static void
  Set64BitInitialTensorValue(poplar::Graph &graph,
  poplar::Tensor &tensor,
  const xla::Literal &literal) {
  - int64 num_elements(ShapeUtil::ElementsIn(literal.shape()));
  + size_t element_count = literal.element_count();
  const void* data(static_cast<const void*>(literal.untyped_data()));
  std::vector<char> converted =
  - ConvInt64ToInt32(data, num_elements * sizeof(int64), 0);
  + ConvInt64ToInt32(data, element_count * sizeof(int64), 0);
  - const int32* data32 = reinterpret_cast<const int32*>(converted.data());
  - graph.setInitialValue<int>(tensor, static_cast<const int*>(data32));
  + int32* data32 = reinterpret_cast<int32*>(converted.data());
  + poplar::ArrayRef<int32> array(data32, element_count);
  + graph.setInitialValue<int>(tensor, array);
  }
  StatusOr<poplar::Tensor>
  