Support for reference convert_fx working on gpu
Summary:
This PR enables gpu only quantization, best used with is_reference since
there are not many gpu kernels for ops as of now.
This PR mainly changes how qconfigs and their obs constructors operate once they
on modules qconfig. The function add_module_to_qconfig_obs_ctr takes the obs constructors on the original
qconfig, and configures them so that when invoked, the created obs will
be on whatever device the module occupies. (Once observers are created,
module.to(device) is already setup so that it moves any observers). To do this,
a new method and a few small chanegs were added to the _PartialWrapper class that
our observers already use to create constructors (without changing the
existing functionality). These changes work in
concert with changes to the prepare flow such that when the qconfigs are
propagated to the moduels (in quantize.py and qconfig_utils.py) they are configured using add_module_to_qconfig_obs_ctr.
Ideally this would work on other models but the is_reference support for
a lot of modules isn't there yet, those tests should be added in a
future PR
Test Plan:
python test/test_quantization.py TestQuantizeFxModels.test_static_gpu_convert_basic
python test/test_quantization.py TestQuantizeFxModels.test_switch_device_prepare_convert
python test/test_quantization.py TestQuantizeFxModels.test_prepare_serialize_switch_device_convert
python test/test_quantization.py TestQuantizeFx.test_qconfig_precedence
Reviewed By: vkuzo
Differential Revision: D29684114
fbshipit-source-id: 19fefb8e1998eaf212723e836276ccf39467f2e7
