Fix regression that caused xrange to be ignored.

PiperOrigin-RevId: 215844450

tensorflow/python/autograph/operators/py_builtins.py

@@ -228,5 +228,6 @@ BUILTIN_FUINCTIONS_MAP = {
     'len': len_,
     'print': print_,
     'range': range_,
+    # TODO(mdan): This might make more sense as tf.data.range.
     'xrange': range_,
 }

tensorflow/python/autograph/pyct/inspect_utils.py

@@ -30,10 +30,14 @@ from tensorflow.python.util import tf_inspect
 
 
 def isbuiltin(f):
+  """Returns True if the argument is a built-in function."""
   # Note these return false for isinstance(f, types.BuiltinFunctionType) so we
   # need to specifically check for them.
   if f in (range, int, float):
     return True
+  if six.PY2:
+    if f in (xrange,):
+      return True
   if isinstance(f, types.BuiltinFunctionType):
     return True
   if tf_inspect.isbuiltin(f):

tensorflow/python/autograph/pyct/static_analysis/live_values.py

@@ -24,6 +24,7 @@ from __future__ import division
 from __future__ import print_function
 
 import gast
+import six
 
 from tensorflow.python.autograph.pyct import anno
 from tensorflow.python.autograph.pyct import transformer
@@ -35,6 +36,9 @@ from tensorflow.python.autograph.pyct.static_analysis.annos import NodeAnno
 # These symbols are legal in Python, but don't appear in the namespace.
 _SPECIAL_SYMBOLS = {'range': range, 'print': print}
 
+if six.PY2:
+  _SPECIAL_SYMBOLS['xrange'] = xrange
+
 
 class LiveValueResolver(transformer.Base):
   """Annotates nodes with live values."""