[quant] Return default qconfig when backend is 'none' (#38407)

supriyar · facebook-github-bot · commit cbff959bd710 · 2020-05-14T09:53:50.000-07:00
Summary: Pull Request resolved: #38407 We can still run some quantized tests even when fbgemm/qnnpack isn't enabled Test Plan: python test/test_quantization.py Imported from OSS Differential Revision: D21554257 fbshipit-source-id: e4fa8f61f6a6717881c00620ed7938c01ffbf958
diff --git a/test/quantization/test_quantize_script.py b/test/quantization/test_quantize_script.py
@@ -1101,12 +1101,7 @@ class TestQuantizeScriptPTSQOps(JitTestCase):
     for individual ops end to end.
     """
     def _test_op_impl(self, module, data, quantized_op):
-        qengine = torch.backends.quantized.engine
-        if qengine == 'none':
-            qconfig = default_qconfig
-        else:
-            qconfig = get_default_qconfig(qengine)
-        qconfig_dict = {'': qconfig}
+        qconfig_dict = {'': get_default_qconfig(torch.backends.quantized.engine)}
         model = torch.jit.script(module).eval()
         model = quantize_script(model, qconfig_dict, _test_only_eval_fn, [data], inplace=False)
         FileCheck().check(quantized_op) \
diff --git a/torch/quantization/qconfig.py b/torch/quantization/qconfig.py
@@ -18,7 +18,7 @@ class QConfig(namedtuple('QConfig', ['activation', 'weight'])):
     Observer classes have usually reasonable default arguments, but they can be overwritten with `with_args`
     method (that behaves like functools.partial):
 
-      my_qconfig = QConfig(activation=MinMaxObserver.with_args(dtype=torch.qint8), 
+      my_qconfig = QConfig(activation=MinMaxObserver.with_args(dtype=torch.qint8),
       weight=default_observer.with_args(dtype=torch.qint8))
     """
     def __new__(cls, activation, weight):
@@ -83,7 +83,7 @@ def get_default_qconfig(backend='fbgemm'):
         qconfig = QConfig(activation=HistogramObserver.with_args(reduce_range=False),
                           weight=default_weight_observer)
     else:
-        raise ValueError("Unknown backend, please specify qconfig manually")
+        qconfig = default_qconfig
     return qconfig
 
 def get_default_qat_qconfig(backend='fbgemm'):
@@ -101,6 +101,5 @@ def get_default_qat_qconfig(backend='fbgemm'):
                                                             reduce_range=False),
                           weight=default_weight_fake_quant)
     else:
-        raise ValueError("Unknown backend, please specify qconfig manually")
-
+        qconfig = default_qat_qconfig
     return qconfig
