Torch to ONNX conversion: Exporting the operator ::_convolution_mode to ONNX opset version 13 is not supported

Feynman27: <p>I’m trying to convert a (fairly simple) 1D depthwise-separable resnet to ONNX. However, when calling <code>torch.onnx.export</code>, I’m getting an UnsupportedOperatorError:</p>
<pre><code class="lang-auto">torch.onnx.symbolic_registry.UnsupportedOperatorError: Exporting the operator ::_convolution_mode to ONNX opset version 13 is not supported. Please feel free to request support or submit a pull request on PyTorch GitHub.
</code></pre>
<p>I don’t see any obvious operators that shouldn’t be supported. Code to reproduce is provided below:</p>
<pre><code class="lang-python">import torch
import torch.nn as nn

class DepthwiseSeparable1D(nn.Module):
    def __init__(self, in_channels, out_channels, kernel_size, stride, bias=False, padding='valid'):
        super(DepthwiseSeparable1D, self).__init__()
        self.dw = nn.Conv1d(
            in_channels=in_channels,
            out_channels=in_channels,
            groups=in_channels,
            kernel_size=kernel_size,
            bias=bias,
            stride=stride,
            padding=padding
        )
        self.pw = nn.Conv1d(
            in_channels=in_channels,
            out_channels=out_channels,
            kernel_size=1,
            bias=bias,
            padding=padding,
        )

    def forward(self, x):
        x = self.dw(x)
        x = self.pw(x)
        return x

class ResidualBlock1D(nn.Module):
    def __init__(self, sub_blocks, filters, kernel_size, stride=1, padding='valid'):
        super(ResidualBlock1D, self).__init__()
        self.sub_blocks = sub_blocks
        self.padding = padding
        self.conv1a = nn.Conv1d(
            in_channels=225, out_channels=filters,
            kernel_size=1, stride=stride, bias=False
        )
        self.bn1a = nn.BatchNorm1d(filters)
        self.block_conv = nn.Sequential()
        self.bn = nn.Sequential()
        for i in range(self.sub_blocks):
            self.block_conv.append(
                DepthwiseSeparable1D(
                    in_channels=filters,
                    out_channels=filters,
                    kernel_size=kernel_size,
                    stride=stride if i == 0 else 1,
                    padding=padding,
                    bias=False,
                )
            )
            self.bn.append(nn.BatchNorm1d(filters))

    def forward(self, inputs):
        res = self.conv1a(inputs)
        res = self.bn1a(res)

        output = inputs
        for i in range(self.sub_blocks):
            output = self.block_conv[i](output)
            output = self.bn[i](output)
            if i == self.sub_blocks - 1:
                if self.padding == 'valid':
                    res = res[:, :, -output.shape[-1]:]
                output = res + output
            output = nn.ReLU(inplace=True)(output)
        return output


class SeparableResNet1D(nn.Sequential):
    def __init__(
        self,
        blocks,
        sub_blocks,
        filters,
        kernel_size,
        strides,
        last_layer_filters = 1024,
        padding='valid',
    ):
        super(SeparableResNet1D, self).__init__()

        self.padding = padding
        if not strides:
            strides = [1]
        strides += [1 for _ in range(blocks + 1 - len(strides))]

        if isinstance(kernel_size, int):
            kernel_size = [kernel_size for _ in range(blocks + 1)]
        # Depthwise conv
        self.append(
            DepthwiseSeparable1D(
                in_channels=64,
                out_channels=filters,
                bias=False,
                kernel_size=kernel_size[0],
                stride=strides[0],
                padding=self.padding,
            )
        )
        for k in range(blocks):
            self.append(
                ResidualBlock1D(
                    sub_blocks=sub_blocks,
                    filters=filters,
                    kernel_size=kernel_size[k+1],
                    padding=padding,
                    stride=strides[k+1]
                )
            )
        self.append(nn.Conv1d(
            in_channels=filters,
            out_channels=last_layer_filters,
            kernel_size=1,
            bias=False,
            padding='valid'
        ))
        self.append(
            nn.BatchNorm1d(num_features=last_layer_filters)
        )
        self.append(
            nn.ReLU()
        )

class MyModel(nn.Module):
    def __init__(self, encoder, last_layer_filters, num_classes=2):
        super(MyModel, self).__init__()
        self.encoder = encoder
        self.linear_model = nn.Sequential(
            nn.Conv1d(in_channels=last_layer_filters, out_channels=2, kernel_size=1), nn.Softmax(dim=1)
        )

    def forward(self, inputs):
        out = self.linear_model(self.encoder(inputs))
        return out


last_layer_filters = 1024
encoder = SeparableResNet1D(
    blocks=6, sub_blocks=3, filters=225, kernel_size=3, strides=[3], padding='valid',
    last_layer_filters=last_layer_filters
)
model = MyModel(
    encoder, last_layer_filters
)
model.eval()
torch.save(model.state_dict(), "toy_resnet_L.pth")
dummy_input = torch.randn([2, 64, 111])
export_model = MyModel(
    encoder, last_layer_filters
)
export_model.load_state_dict(torch.load("toy_resnet_L.pth"))
export_model.eval()
out = export_model(dummy_input)
torch.onnx.export(
    export_model, dummy_input, "resnet_L.random.onnx",
    verbose=True,
)

</code></pre>

Feynman27: <p>Here’s a minimal code to reproduce the issue:</p>
<pre><code class="lang-python">import torch
import torch.nn as nn

class MyModel(nn.Module):
    def __init__(self, last_layer_filters, num_classes=2):
        super(MyModel, self).__init__()
        self.linear_model = nn.Sequential(
            nn.Conv1d(in_channels=last_layer_filters, out_channels=num_classes, kernel_size=1, padding='valid'),
            nn.Softmax(dim=1)
        )

    def forward(self, inputs):
        out = self.linear_model(inputs)
        return out


last_layer_filters = 1024
model = MyModel(
    last_layer_filters
)
model.eval()
torch.save(model.state_dict(), "toy_model.pth")
dummy_input = torch.randn([1, last_layer_filters, 1])
export_model = MyModel(
    last_layer_filters
)
export_model.load_state_dict(torch.load("toy_model.pth"))
export_model.eval()
out = export_model(dummy_input)
torch.onnx.export(
    export_model, dummy_input, "scratch.onnx",
    verbose=True,
)
</code></pre>

Feynman27: <p>Appears that if I take out the <code>padding</code> arguments everywhere, it works. Why is that?</p>

ptrblck: <p>I guess ONNX doesn’t support this argument (yet). You could check their opset support to see if it’s already implemented in a specific version or planned.</p>