fix error (#3843)

ppdet/modeling/heads/s2anet_head.py

@@ -551,7 +551,6 @@ class S2ANetHead(nn.Layer):
             fam_cls_score1 = fam_cls_score
 
             feat_labels = paddle.to_tensor(feat_labels)
-            if (feat_labels >= 0).astype(paddle.int32).sum() > 0:
             feat_labels_one_hot = paddle.nn.functional.one_hot(
                 feat_labels, self.cls_out_channels + 1)
             feat_labels_one_hot = feat_labels_one_hot[:, 1:]
@@ -575,8 +574,6 @@ class S2ANetHead(nn.Layer):
 
             fam_cls = fam_cls * feat_label_weights
             fam_cls_total = paddle.sum(fam_cls)
-            else:
-                fam_cls_total = paddle.zeros([0], dtype=fam_cls_score1.dtype)
             fam_cls_losses.append(fam_cls_total)
 
             # step3: regression loss
@@ -673,7 +670,6 @@ class S2ANetHead(nn.Layer):
             odm_cls_score1 = odm_cls_score
 
             feat_labels = paddle.to_tensor(feat_labels)
-            if (feat_labels >= 0).astype(paddle.int32).sum() > 0:
             feat_labels_one_hot = paddle.nn.functional.one_hot(
                 feat_labels, self.cls_out_channels + 1)
             feat_labels_one_hot = feat_labels_one_hot[:, 1:]
@@ -696,8 +692,6 @@ class S2ANetHead(nn.Layer):
 
             odm_cls = odm_cls * feat_label_weights
             odm_cls_total = paddle.sum(odm_cls)
-            else:
-                odm_cls_total = paddle.zeros([0], dtype=odm_cls_score1.dtype)
             odm_cls_losses.append(odm_cls_total)
 
             # # step3: regression loss