[Feature] Register a new activatation layer SiLU to ACTIVATION_LAYERS (#2256)

mmcv/cnn/bricks/activation.py

@@ -14,6 +14,9 @@ for module in [
 ]:
     ACTIVATION_LAYERS.register_module(module=module)
 
+if digit_version(torch.__version__) >= digit_version('1.7.0'):
+    ACTIVATION_LAYERS.register_module(module=nn.SiLU)
+
 
 @ACTIVATION_LAYERS.register_module(name='Clip')
 @ACTIVATION_LAYERS.register_module()

tests/test_cnn/test_silu.py

@@ -0,0 +1,21 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import pytest
+import torch
+import torch.nn.functional as F
+
+from mmcv.cnn.bricks import build_activation_layer
+from mmcv.utils import digit_version
+
+
+@pytest.mark.skipif(
+    digit_version(torch.__version__) < digit_version('1.7.0'),
+    reason='torch.nn.SiLU is not available before 1.7.0')
+def test_silu():
+    act = build_activation_layer(dict(type='SiLU'))
+    input = torch.randn(1, 3, 64, 64)
+    expected_output = F.silu(input)
+    output = act(input)
+    # test output shape
+    assert output.shape == expected_output.shape
+    # test output value
+    assert torch.equal(output, expected_output)