fix swipe eval

fmoe/gates/swipe_gate.py

@@ -26,11 +26,11 @@ class SwipeGate(NaiveGate):
 
     def forward(self, inp):
         score = self.gate(inp)
-        _, orig_idx = torch.topk(score, k=self.top_k, dim=-1)
+        orig_score, orig_idx = torch.topk(score, k=self.top_k, dim=-1)
 
         if not self.training:
-            topk_val = F.softmax(topk_val, dim=-1)
-            return topk_idx, topk_val
+            topk_val = F.softmax(orig_score, dim=-1)
+            return orig_idx, topk_val
 
         capacity = torch.scalar_tensor(inp.shape[0] * self.top_k,
                 dtype=torch.long)