message: Rebalance slice during layout transformation
  Summary:
  Expand deducted slice input tensor and rotate clones' mappings.
  Fix T62661.
  Reviewers: #tensorflow, #framework_ip_review_-_any_oss_or_third-party_code_use_has_been_approved, samuelh, babakk, georgep
  Maniphest Tasks: T62661
diff: @@ -425,10 +425,18 @@ DriverTensor CreateTensorFromSlice(
  // Make a clone of the slice.
  output_slices[0] = TensorCloneAndRebalanceAliasing(
  graph, resources, adjusted_slice, {debug_name_and_id});
  + auto mapping = graph.getTileMapping(output_slices[0]);
  + auto width = MappingHelper::GetMappingWidth(mapping);
  + VLOG(2) << "Slice mapping size " << width << " replicated "
  + << number_of_clones << " times.";
  // The remaining slices will just clone the layout of the first slice.
  for (int64_t i = 1; i != number_of_clones; ++i) {
  output_slices[i] = graph.clone(output_slices[0], {debug_name_and_id});
  + auto mapping = graph.getTileMapping(output_slices[i]);
  + MappingHelper::RotateMapping(graph, mapping, width * i);
  + graph.getPoplarGraph().setTileMapping(output_slices[i].getPoplarTensor(),
  + mapping);
  }
  // Concatentate all the slices into a single tensor.
  