Refactor cudnn convolution (#49109)
Summary:
cuDNN v7 API has been deprecated, so we need to migrate to cuDNN v8 API. The v8 API does not exist on cuDNN 7, so there will be a long time both API should exist.
This is step 0 of adding cuDNN v8 API. There is no real code change in this PR. It just copy-pastes existing code. The original `Conv.cpp` is split into `ConvPlaceholders.cpp`, `ConvShared.cpp`, `ConvShared.h`, `Conv_v7.cpp`, `Conv_v8.cpp`. Currently `Conv_v8.cpp` is empty, and will be filled in the future.
The `ConvPlaceholders.cpp` contains placeholder implementation of cudnn convolution when cudnn is not enabled. These operators only raise errors and do no real computation. This file also contains deprecated operators. These operators are implemented using current operators.
The `ConvShared.cpp` and `ConvShared.h` contains code that will be shared by the v7 and v8 API, these include the definition of struct `ConvolutionParams` and `ConvolutionArgs`. As well as ATen exposed API like `cudnn_convolution` and intermediate `cudnn_convolution_forward`. These exposed functions will call raw API like `raw_cudnn_convolution_forward_out` in `Conv_v7.cpp` or `Conv_v8.cpp` for the real implementation.
The `Conv_v7.cpp`, `Conv_v8.cpp` contains the implementation of raw APIs, and are different for v7 and v8.
Pull Request resolved: https://github.com/pytorch/pytorch/pull/49109
Reviewed By: H-Huang
Differential Revision: D25463783
Pulled By: ezyang
fbshipit-source-id: 1c80de8e5d94d97a61e45687f6193e8ff5481e3e
