AttributeError: module 'tvm.relay.op.nn' has no attribute 'div'

when I try to auto-tune the tensorflow inference from pb file, error occured in the stage of net, params = relay.frontend.from_tensorflow(graph_def, layout=layout, shape=shape_dict):
File /home/dolphin/.tvm_test_data/data/elephant-299.jpg exists, skip.
Tensorflow protobuf imported to relay frontend.
Extract tasks…
Traceback (most recent call last):
File “/home/dolphin/tvm/python/tvm/relay/frontend/tensorflow.py”, line 39, in _get_relay_op
op = getattr(_op, op_name)
AttributeError: module ‘tvm.relay.op’ has no attribute ‘div’

Traceback (most recent call last):
File “/home/dolphin/tvm/python/tvm/relay/frontend/tensorflow.py”, line 42, in _get_relay_op
op = getattr(_op.nn, op_name)
AttributeError: module ‘tvm.relay.op.nn’ has no attribute ‘div’

what reason caused this error? and How to locate where this op is in the Graph? Thanks in advance!

after putting the prints in the file of ~/tvm/python/tvm/relay/frontend/tensorflow.py, the result shows there is preprocess module before the input of inference module in the graph: preprocess/truediv_1 which contains div
elif node.op != “Placeholder”:
# Pass the parsed shapes instead
attr["_output_shapes"] = output_shapes = self._output_shapes[node.name]
print(‘show where the error’)
print(node.name)