Implementation of YOLACT forward_dummy to enable get_flops (#6079)

* update forward_dummy

* improve code

* fix lint

* include forward_dummy in unit test

* remove hardcode

* fix lint

* fix bug

* change simple_test to forward

* update forward_dummy

* fix problems

* add test comment

* fix lint

Author: Collin Zhang

mmdet/models/dense_heads/yolact_head.py

@@ -663,6 +663,10 @@ def _init_layers(self):
             protonets = protonets[:-1]
         return nn.Sequential(*protonets)
 
+    def forward_dummy(self, x):
+        prototypes = self.protonet(x)
+        return prototypes
+
     def forward(self, x, coeff_pred, bboxes, img_meta, sampling_results=None):
         """Forward feature from the upstream network to get prototypes and
         linearly combine the prototypes, using masks coefficients, into

mmdet/models/detectors/yolact.py

@@ -30,7 +30,10 @@ def forward_dummy(self, img):
 
         See `mmdetection/tools/analysis_tools/get_flops.py`
         """
-        raise NotImplementedError
+        feat = self.extract_feat(img)
+        bbox_outs = self.bbox_head(feat)
+        prototypes = self.mask_head.forward_dummy(feat[0])
+        return (bbox_outs, prototypes)
 
     def forward_train(self,
                       img,

tests/test_models/test_forward.py

@@ -541,6 +541,9 @@ def test_yolact_forward():
         return_loss=True)
     assert isinstance(losses, dict)
 
+    # Test forward dummy for get_flops
+    detector.forward_dummy(imgs)
+
     # Test forward test
     detector.eval()
     with torch.no_grad():