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# Copyright (c) 2021, NVIDIA CORPORATION. All rights reserved. | |
# | |
# NVIDIA CORPORATION and its licensors retain all intellectual property | |
# and proprietary rights in and to this software, related documentation | |
# and any modifications thereto. Any use, reproduction, disclosure or | |
# distribution of this software and related documentation without an express | |
# license agreement from NVIDIA CORPORATION is strictly prohibited. | |
"""Custom replacement for `torch.nn.functional.conv2d` that supports | |
arbitrarily high order gradients with zero performance penalty.""" | |
import warnings | |
import contextlib | |
import torch | |
# pylint: disable=redefined-builtin | |
# pylint: disable=arguments-differ | |
# pylint: disable=protected-access | |
#---------------------------------------------------------------------------- | |
enabled = False # Enable the custom op by setting this to true. | |
weight_gradients_disabled = False # Forcefully disable computation of gradients with respect to the weights. | |
def no_weight_gradients(): | |
global weight_gradients_disabled | |
old = weight_gradients_disabled | |
weight_gradients_disabled = True | |
yield | |
weight_gradients_disabled = old | |
def conv2d(input, weight, bias=None, stride=1, padding=0, dilation=1, groups=1): | |
if _should_use_custom_op(input): | |
return _conv2d_gradfix(transpose=False, weight_shape=weight.shape, stride=stride, padding=padding, output_padding=0, dilation=dilation, groups=groups).apply(input, weight, bias) | |
return torch.nn.functional.conv2d(input=input, weight=weight, bias=bias, stride=stride, padding=padding, dilation=dilation, groups=groups) | |
def conv_transpose2d(input, weight, bias=None, stride=1, padding=0, output_padding=0, groups=1, dilation=1): | |
if _should_use_custom_op(input): | |
return _conv2d_gradfix(transpose=True, weight_shape=weight.shape, stride=stride, padding=padding, output_padding=output_padding, groups=groups, dilation=dilation).apply(input, weight, bias) | |
return torch.nn.functional.conv_transpose2d(input=input, weight=weight, bias=bias, stride=stride, padding=padding, output_padding=output_padding, groups=groups, dilation=dilation) | |
def _should_use_custom_op(input): | |
assert isinstance(input, torch.Tensor) | |
if (not enabled) or (not torch.backends.cudnn.enabled): | |
return False | |
if input.device.type != 'cuda': | |
return False | |
if any(torch.__version__.startswith(x) for x in ['1.7.', '1.8.', '1.9']): | |
return True | |
return False | |
def _tuple_of_ints(xs, ndim): | |
xs = tuple(xs) if isinstance(xs, (tuple, list)) else (xs,) * ndim | |
assert len(xs) == ndim | |
assert all(isinstance(x, int) for x in xs) | |
return xs | |
_conv2d_gradfix_cache = dict() | |
def _conv2d_gradfix(transpose, weight_shape, stride, padding, output_padding, dilation, groups): | |
# Parse arguments. | |
ndim = 2 | |
weight_shape = tuple(weight_shape) | |
stride = _tuple_of_ints(stride, ndim) | |
padding = _tuple_of_ints(padding, ndim) | |
output_padding = _tuple_of_ints(output_padding, ndim) | |
dilation = _tuple_of_ints(dilation, ndim) | |
# Lookup from cache. | |
key = (transpose, weight_shape, stride, padding, output_padding, dilation, groups) | |
if key in _conv2d_gradfix_cache: | |
return _conv2d_gradfix_cache[key] | |
# Validate arguments. | |
assert groups >= 1 | |
assert len(weight_shape) == ndim + 2 | |
assert all(stride[i] >= 1 for i in range(ndim)) | |
assert all(padding[i] >= 0 for i in range(ndim)) | |
assert all(dilation[i] >= 0 for i in range(ndim)) | |
if not transpose: | |
assert all(output_padding[i] == 0 for i in range(ndim)) | |
else: # transpose | |
assert all(0 <= output_padding[i] < max(stride[i], dilation[i]) for i in range(ndim)) | |
# Helpers. | |
common_kwargs = dict(stride=stride, padding=padding, dilation=dilation, groups=groups) | |
def calc_output_padding(input_shape, output_shape): | |
if transpose: | |
return [0, 0] | |
return [ | |
input_shape[i + 2] | |
- (output_shape[i + 2] - 1) * stride[i] | |
- (1 - 2 * padding[i]) | |
- dilation[i] * (weight_shape[i + 2] - 1) | |
for i in range(ndim) | |
] | |
# Forward & backward. | |
class Conv2d(torch.autograd.Function): | |
def forward(ctx, input, weight, bias): | |
assert weight.shape == weight_shape | |
if not transpose: | |
output = torch.nn.functional.conv2d(input=input, weight=weight, bias=bias, **common_kwargs) | |
else: # transpose | |
output = torch.nn.functional.conv_transpose2d(input=input, weight=weight, bias=bias, output_padding=output_padding, **common_kwargs) | |
ctx.save_for_backward(input, weight) | |
return output | |
def backward(ctx, grad_output): | |
input, weight = ctx.saved_tensors | |
grad_input = None | |
grad_weight = None | |
grad_bias = None | |
if ctx.needs_input_grad[0]: | |
p = calc_output_padding(input_shape=input.shape, output_shape=grad_output.shape) | |
grad_input = _conv2d_gradfix(transpose=(not transpose), weight_shape=weight_shape, output_padding=p, **common_kwargs).apply(grad_output, weight, None) | |
assert grad_input.shape == input.shape | |
if ctx.needs_input_grad[1] and not weight_gradients_disabled: | |
grad_weight = Conv2dGradWeight.apply(grad_output, input) | |
assert grad_weight.shape == weight_shape | |
if ctx.needs_input_grad[2]: | |
grad_bias = grad_output.sum([0, 2, 3]) | |
return grad_input, grad_weight, grad_bias | |
# Gradient with respect to the weights. | |
class Conv2dGradWeight(torch.autograd.Function): | |
def forward(ctx, grad_output, input): | |
op = torch._C._jit_get_operation('aten::cudnn_convolution_backward_weight' if not transpose else 'aten::cudnn_convolution_transpose_backward_weight') | |
flags = [torch.backends.cudnn.benchmark, torch.backends.cudnn.deterministic, torch.backends.cudnn.allow_tf32] | |
grad_weight = op(weight_shape, grad_output, input, padding, stride, dilation, groups, *flags) | |
assert grad_weight.shape == weight_shape | |
ctx.save_for_backward(grad_output, input) | |
return grad_weight | |
def backward(ctx, grad2_grad_weight): | |
grad_output, input = ctx.saved_tensors | |
grad2_grad_output = None | |
grad2_input = None | |
if ctx.needs_input_grad[0]: | |
grad2_grad_output = Conv2d.apply(input, grad2_grad_weight, None) | |
assert grad2_grad_output.shape == grad_output.shape | |
if ctx.needs_input_grad[1]: | |
p = calc_output_padding(input_shape=input.shape, output_shape=grad_output.shape) | |
grad2_input = _conv2d_gradfix(transpose=(not transpose), weight_shape=weight_shape, output_padding=p, **common_kwargs).apply(grad_output, grad2_grad_weight, None) | |
assert grad2_input.shape == input.shape | |
return grad2_grad_output, grad2_input | |
_conv2d_gradfix_cache[key] = Conv2d | |
return Conv2d | |