message: Add xla.compile() example
diff: @@ -58,7 +58,7 @@ sess = tf.Session(config=config)
  > compiled for the CPU. JIT compilation for CPU operations must be done via
  > the manual method documented below.
  -#### Manual
  +#### Manual with experimental_jit_scope()
  JIT compilation can also be turned on manually for one or more operators. This
  is done by tagging the operators to compile with the attribute
  @@ -79,6 +79,16 @@ The `_XlaCompile` attribute is currently supported on a best-effort basis. If an
  operator cannot be compiled, TensorFlow will silently fall back to the normal
  implementation.
  +#### Manual with xla.compile()
  +
  +Unlike experimental_jit_scope() which silently falls back to normal Tensorflow
  +on uncompilable operator, xla.compile() returns an explicit error. This is
  +useful if you want more predictable behaviors from XLA compilation.
  +
  +Please see
  +[xla.compile() tutorial Colab](https://colab.sandbox.google.com/github/tensorflow/compiler/xla/g3doc/tutorials/xla_compile.ipynb)
  +for how to use it.
  +
  ### Placing operators on XLA devices
  Another way to run computations via XLA is to place an operator on a specific
  