pytorch

975d4284 - [Quant] Add the operator of decomposed fake quant per channel (#121297)

[Quant] Add the operator of decomposed fake quant per channel (#121297) **Summary** Add the operator of `quantized_decomposed.fake_quant_per_channel` and test the forward and backward of this op with comparing to ATen. **Test Plan** ``` python -u -m pytest -s -v test_cpu_repro.py -k test_decomposed_fake_quant_per_channel ``` **Next Step** Optimize the performance: from the generated code of forward and backward graph, the code didn't vectorize. Pull Request resolved: https://github.com/pytorch/pytorch/pull/121297 Approved by: https://github.com/jerryzh168, https://github.com/jgong5