ref: decouple apex second attemp part 1/n (#4052)

pytorch_lightning/accelerators/base_accelerator.py

@@ -76,12 +76,10 @@ class Accelerator(object):
 
         # scale loss for 16 bit
         if self.trainer.precision == 16:
-            closure_loss = model_ref.amp_scale_loss(
-                closure_loss,
-                optimizer,
-                opt_idx,
-                amp_backend=self.trainer.amp_backend
-            )
+            if self.trainer.amp_backend == AMPType.NATIVE:
+                closure_loss = self.trainer.scaler.scale(closure_loss)
+            else:
+                closure_loss = amp.scale_loss(closure_loss, optimizer)
 
             # enter amp context
             if self.trainer.amp_backend == AMPType.APEX:

pytorch_lightning/core/hooks.py

@@ -318,14 +318,6 @@ class ModelHooks:
         """
         loss.backward()
 
-    def amp_scale_loss(self, unscaled_loss: Tensor, optimizer: Optimizer, optimizer_idx: int, amp_backend: AMPType):
-        if amp_backend == AMPType.NATIVE:
-            scaled_loss = self.trainer.scaler.scale(unscaled_loss)
-        else:
-            scaled_loss = amp.scale_loss(unscaled_loss, optimizer)
-
-        return scaled_loss
-
 
 class DataHooks:
     def prepare_data(self) -> None: