SIGSEGV problems when quantization

Troubleshooting
#1

I encountered a problem when using quantize.py. Here is the code I use:

def quantize(mod, params):
    with relay.quantize.qconfig(calibrate_mode='kl_divergence', weight_scale='max'):
        mod = relay.quantize.quantize(mod, params, dataset=calibrate_dataset())
    return mod

An error occurs at: quantize.py#302~307

optimize = tvm.transform.Sequential(
        [_transform.SimplifyInference(),
         _transform.FoldConstant(),
         _transform.FoldScaleAxis(),
         _transform.CanonicalizeOps(),
         _transform.FoldConstant()])

The message:

Exception ignored in: 'tvm._ffi._cy3.core.tvm_callback'
Traceback (most recent call last):
  File "tvm/_ffi/_cython/./packed_func.pxi", line 218, in tvm._ffi._cy3.core.make_ret
ValueError: Unhandled type code 14
Traceback (most recent call last):

  File "tvm/_ffi/_cython/./packed_func.pxi", line 218, in tvm._ffi._cy3.core.make_ret

ValueError: Unhandled type code 14


Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)

After commenting this line, another error happened at quantize.py#355~356

        with quantize_context():
            mod = quantize_seq(mod)

message:

Process finished with exit code 139 (interrupted by signal 11: SIGSEGV)