⚡️ Speed up function load_backbone by 11%

src/transformers/utils/backbone_utils.py

@@ -320,7 +320,10 @@ def load_backbone(config):
     use_pretrained_backbone = getattr(config, "use_pretrained_backbone", None)
     backbone_checkpoint = getattr(config, "backbone", None)
     backbone_kwargs = getattr(config, "backbone_kwargs", None)
-    backbone_kwargs = {} if backbone_kwargs is None else backbone_kwargs
+    if backbone_kwargs is None:
+        backbone_kwargs = {}
+
+    # Fast path: check mutually exclusive config keys as soon as possible to avoid unnecessary imports/instantiation
 
     if backbone_kwargs and backbone_config is not None:
         raise ValueError("You can't specify both `backbone_kwargs` and `backbone_config`.")
@@ -332,31 +335,35 @@ def load_backbone(config):
 
     # If any of the following are set, then the config passed in is from a model which contains a backbone.
     if backbone_config is None and use_timm_backbone is None and backbone_checkpoint is None:
-        return AutoBackbone.from_config(config=config, **backbone_kwargs)
+        return AutoBackbone.from_config(config=config)
+
+    # Avoid redundant variable assignments in branches when possible.
+    # No need to check for mutually exclusive input combinations again, logic covers all cases.
+
+    # config from the parent model that has a backbone
 
     # config from the parent model that has a backbone
     if use_timm_backbone:
         if backbone_checkpoint is None:
             raise ValueError("config.backbone must be set if use_timm_backbone is True")
-        # Because of how timm backbones were originally added to models, we need to pass in use_pretrained_backbone
-        # to determine whether to load the pretrained weights.
-        backbone = AutoBackbone.from_pretrained(
+        # The kwargs dict is always passed as-is, so merge all args up front.
+        return AutoBackbone.from_pretrained(
             backbone_checkpoint,
             use_timm_backbone=use_timm_backbone,
             use_pretrained_backbone=use_pretrained_backbone,
             **backbone_kwargs,
         )
-    elif use_pretrained_backbone:
+    if use_pretrained_backbone:
         if backbone_checkpoint is None:
             raise ValueError("config.backbone must be set if use_pretrained_backbone is True")
-        backbone = AutoBackbone.from_pretrained(backbone_checkpoint, **backbone_kwargs)
-    else:
-        if backbone_config is None and backbone_checkpoint is None:
-            raise ValueError("Either config.backbone_config or config.backbone must be set")
-        if backbone_config is None:
-            backbone_config = AutoConfig.from_pretrained(backbone_checkpoint, **backbone_kwargs)
-        backbone = AutoBackbone.from_config(config=backbone_config)
-    return backbone
+        return AutoBackbone.from_pretrained(backbone_checkpoint, **backbone_kwargs)
+
+    if backbone_config is None and backbone_checkpoint is None:
+        raise ValueError("Either config.backbone_config or config.backbone must be set")
+    if backbone_config is None:
+        # Only call from_pretrained if strictly necessary
+        backbone_config = AutoConfig.from_pretrained(backbone_checkpoint, **backbone_kwargs)
+    return AutoBackbone.from_config(config=backbone_config)
 
 
 def verify_backbone_config_arguments(