Handle uninitialized min/max values in histogram observer (#27151)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/27151
We need to be ab le to handle observers with no min/max data correctly as models sometimes have modules that do not get any data.
ghstack-source-id: 91113403
Test Plan:
buck test caffe2/test:quantization -- test_minmax_observer
buck test caffe2/test:quantization -- test_per_channel_minmax_observer
buck test caffe2/test:quantization --test_histogram_observer
Reviewed By: csummersea
Differential Revision: D17690828
fbshipit-source-id: e95709333ea0f66d79ddb8141b7cba5a83347dbd
