PegasusForConditionalGeneration (torch version) (#6340)

Co-authored-by: Jingqing  Zhang <jingqing.zhang15@imperial.ac.uk>

examples/seq2seq/distillation.py

@@ -413,6 +413,18 @@ def get_layers_to_copy(n_to_get, tot):
             12: all_layers,
         }
         return layers_to_copy[n_to_get]
+    elif tot == 16:
+        layers_to_copy = {  # maps  num layers in student -> which teacher layers to copy
+            1: [0],
+            2: [0, 8],
+            3: [0, 8, 15],
+            4: [0, 5, 10, 15],
+            6: [0, 3, 6, 9, 12, 15],
+            8: [0, 2, 4, 6, 8, 10, 12, 15],
+            9: [0, 1, 3, 5, 7, 9, 11, 13, 15],
+            16: all_layers,
+        }
+        return layers_to_copy[n_to_get]
     else:
         return all_layers[:n_to_get]  # TODO: better version on theseus-bart branch