message: [XLA/Docs] Documented a requirement for bounded while loops
diff: @@ -30,3 +30,12 @@ random operations, such as `tf.random.normal`, or `tf.nn.dropout`. XLA will
  behave as if the compilation was seeded with a new unique seed at each run. This
  limitation does not apply to stateless random ops.
  +## TensorFlow while loops need to be bounded (or have backprop disabled)
  +
  +TF while [loops](https://www.tensorflow.org/api_docs/python/tf/while_loop)
  +created using `tf.while_loop` support backpropagation by accumulating all
  +intermediate results in a `TensorArray`.
  +
  +Since XLA only supports bounded `TensorArray`s, all compiled while loops need to
  +either have `maximum_iterations` parameter set to a constant value known at
  +compile time, or backpropagation disabled using `back_prop=False`.
  