[Feature] Support modulated_deform_conv with cambricon MLU backend (#2411)

* [Feature] Support modulated_deform_conv with cambricon MLU backend

* fix error of torch_mlu

* modify with commit suggestion

* Update modulated_deform_conv.py

* Update mmcv/ops/modulated_deform_conv.py
Co-authored-by: Zaida Zhou <58739961+zhouzaida@users.noreply.github.com>

docs/en/understand_mmcv/ops.md

@@ -32,7 +32,7 @@ We implement common ops used in detection, segmentation, etc.
 | MaskedConv                   |     | √    | √   |     | √   |
 | MergeCells                   |     | √    |     |     |     |
 | MinAreaPolygon               |     | √    |     |     |     |
-| ModulatedDeformConv2d        | √   | √    |     |     | √   |
+| ModulatedDeformConv2d        | √   | √    | √   |     | √   |
 | MultiScaleDeformableAttn     |     | √    | √   |     |     |
 | NMS                          | √   | √    | √   |     | √   |
 | NMSRotated                   | √   | √    |     |     |     |

docs/zh_cn/understand_mmcv/ops.md

@@ -32,7 +32,7 @@ MMCV 提供了检测、分割等任务中常用的算子
 | MaskedConv                   |     | √    | √   |     | √   |
 | MergeCells                   |     | √    |     |     |     |
 | MinAreaPolygon               |     | √    |     |     |     |
-| ModulatedDeformConv2d        | √   | √    |     |     | √   |
+| ModulatedDeformConv2d        | √   | √    | √   |     | √   |
 | MultiScaleDeformableAttn     |     | √    | √   |     |     |
 | NMS                          | √   | √    | √   |     | √   |
 | NMSRotated                   | √   | √    |     |     |     |

mmcv/ops/__init__.py

 # Copyright (c) OpenMMLab. All rights reserved.
+from mmcv.utils import IS_MLU_AVAILABLE
 from .active_rotated_filter import active_rotated_filter
 from .assign_score_withk import assign_score_withk
 from .ball_query import ball_query
@@ -106,3 +107,8 @@ __all__ = [
     'diff_iou_rotated_2d', 'diff_iou_rotated_3d', 'chamfer_distance',
     'PrRoIPool', 'prroi_pool'
 ]
+
+if IS_MLU_AVAILABLE:
+    from .modulated_deform_conv import \
+        ModulatedDeformConv2dPack_MLU  # noqa:F401
+    __all__.append('ModulatedDeformConv2dPack_MLU')

mmcv/ops/modulated_deform_conv.py

@@ -8,7 +8,7 @@ from torch.autograd import Function
 from torch.autograd.function import once_differentiable
 from torch.nn.modules.utils import _pair, _single
 
-from mmcv.utils import deprecated_api_warning
+from mmcv.utils import IS_MLU_AVAILABLE, deprecated_api_warning
 from ..cnn import CONV_LAYERS
 from ..utils import ext_loader, print_log
 
@@ -352,3 +352,88 @@ class ModulatedDeformConv2dPack(ModulatedDeformConv2d):
         super()._load_from_state_dict(state_dict, prefix, local_metadata,
                                       strict, missing_keys, unexpected_keys,
                                       error_msgs)
+
+
+if IS_MLU_AVAILABLE:
+    from torchvision.ops import deform_conv2d as tv_deform_conv2d
+
+    @CONV_LAYERS.register_module('DCNv2', force=True)
+    class ModulatedDeformConv2dPack_MLU(nn.modules.Module):
+        """This class is the DCNv2 implementation of the MLU device. The MLU
+        backend support of the operator has been implemented in torchvision.
+        The mmcv registration mechanism is used for multiplexing here. The
+        torchvision implementation of DCNv2 is called.
+
+        Args:
+            in_channels (int): Same as nn.Conv2d.
+            out_channels (int): Same as nn.Conv2d.
+            kernel_size (int or tuple[int]): Same as nn.Conv2d.
+            stride (int): Same as nn.Conv2d, while tuple is not supported.
+            padding (int): Same as nn.Conv2d, while tuple is not supported.
+            dilation (int): Same as nn.Conv2d, while tuple is not supported.
+            groups (int): Same as nn.Conv2d.
+            bias (bool or str): If specified as `auto`, it will be decided by
+                the norm_cfg. Bias will be set as True if norm_cfg is None,
+                otherwise False.
+        """
+
+        def __init__(self,
+                     in_channels: int,
+                     out_channels: int,
+                     kernel_size: Union[int, Tuple[int]],
+                     stride: int = 1,
+                     padding: int = 0,
+                     dilation: int = 1,
+                     groups: int = 1,
+                     deform_groups: int = 1,
+                     bias: Union[bool, str] = True):
+            super().__init__()
+            self.in_channels = in_channels
+            self.out_channels = out_channels
+            self.kernel_size = _pair(kernel_size)
+            self.stride = _pair(stride)
+            self.padding = _pair(padding)
+            self.dilation = _pair(dilation)
+            self.groups = groups
+            self.deform_groups = deform_groups
+            self.weight = nn.Parameter(
+                torch.Tensor(out_channels, in_channels, *self.kernel_size))
+            if bias:
+                self.bias = nn.Parameter(torch.Tensor(out_channels))
+            else:
+                self.register_parameter('bias', None)
+            self.conv_offset = nn.Conv2d(
+                self.in_channels,
+                self.deform_groups * 3 * self.kernel_size[0] *
+                self.kernel_size[1],
+                kernel_size=self.kernel_size,
+                stride=self.stride,
+                padding=self.padding,
+                bias=True)
+            self.init_weights()
+
+        def init_weights(self):
+            n = self.in_channels
+            for k in self.kernel_size:
+                n *= k
+            stdv = 1. / math.sqrt(n)
+            self.weight.data.uniform_(-stdv, stdv)
+            if self.bias is not None:
+                self.bias.data.zero_()
+            self.conv_offset.weight.data.zero_()
+            self.conv_offset.bias.data.zero_()
+
+        def forward(self, x):
+            out = self.conv_offset(x)
+            o1, o2, mask = torch.chunk(out, 3, dim=1)
+            offset = torch.cat((o1, o2), dim=1)
+            mask = torch.sigmoid(mask)
+            return tv_deform_conv2d(
+                x,
+                offset,
+                self.weight,
+                bias=self.bias,
+                stride=self.stride,
+                padding=self.padding,
+                dilation=self.dilation,
+                mask=mask)

tests/test_ops/test_modulated_deform_conv.py

@@ -5,7 +5,7 @@ import numpy
 import pytest
 import torch
 
-from mmcv.utils import TORCH_VERSION, digit_version
+from mmcv.utils import IS_MLU_AVAILABLE, TORCH_VERSION, digit_version
 
 try:
     # If PyTorch version >= 1.6.0 and fp16 is enabled, torch.cuda.amp.autocast
@@ -42,10 +42,14 @@ class TestMdconv:
     def _test_mdconv(self, dtype=torch.float, device='cuda'):
         if not torch.cuda.is_available() and device == 'cuda':
             pytest.skip('test requires GPU')
+        if device == 'mlu':
+            from mmcv.ops import \
+                ModulatedDeformConv2dPack_MLU as ModulatedDeformConv2dPack
+        else:
             from mmcv.ops import ModulatedDeformConv2dPack
+
         input = torch.tensor(input_t, dtype=dtype, device=device)
         input.requires_grad = True
-
         dcn = ModulatedDeformConv2dPack(
             1,
             1,
@@ -53,10 +57,7 @@ class TestMdconv:
             stride=1,
             padding=1,
             deform_groups=1,
-            bias=False)
-
-        if device == 'cuda':
-            dcn.cuda()
+            bias=False).to(device)
 
         dcn.weight.data.fill_(1.)
         dcn.type(dtype)
@@ -114,9 +115,11 @@ class TestMdconv:
     def test_mdconv(self):
         self._test_mdconv(torch.double, device='cpu')
         self._test_mdconv(torch.float, device='cpu')
-        self._test_mdconv(torch.double)
-        self._test_mdconv(torch.float)
-        self._test_mdconv(torch.half)
+
+        device = 'mlu' if IS_MLU_AVAILABLE else 'cuda'
+        self._test_mdconv(torch.double, device=device)
+        self._test_mdconv(torch.float, device=device)
+        self._test_mdconv(torch.half, device=device)
 
         # test amp when torch version >= '1.6.0', the type of
         # input data for mdconv might be torch.float or torch.half