Refactor convolution_backward's CudaDepthwise2d case (#71489)
Summary:
Pull Request resolved: https://github.com/pytorch/pytorch/pull/71489
Deleted unnecessary .contiguous() calls in convolution_backward. The
CudaDepthwise2d case always hits conv_depthwise2d_backward_cuda_out,
which makes the grad_output / self contiguous.
Changed conv_depthwise2d_backward_cuda_out to change `self_` (aka the
image input to convolution) to be contiguous only when we're computing
the grad_weight. This is because when we are computing the grad_input,
we only need the values from the grad_output and the weight.
Test Plan: - pytest test/test_nn.py -v -k "conv"
Reviewed By: jbschlosser
Differential Revision: D33664697
Pulled By: zou3519
fbshipit-source-id: 7a755fa8a076809c5490422d69fdf7ed80c8e29a
(cherry picked from commit 862ae63bab74113b3607b1bbc0a82f27992550fe)
