Support weight padding on diff weight patch (comfyanonymous#4576)

Author: huchenlei

comfy/lora.py

@@ -16,6 +16,7 @@
     along with this program.  If not, see <https://www.gnu.org/licenses/>.
 """
 
+from __future__ import annotations
 import comfy.utils
 import comfy.model_management
 import comfy.model_base
@@ -347,6 +348,39 @@ def weight_decompose(dora_scale, weight, lora_diff, alpha, strength, intermediat
         weight[:] = weight_calc
     return weight
 
+def pad_tensor_to_shape(tensor: torch.Tensor, new_shape: list[int]) -> torch.Tensor:
+    """
+    Pad a tensor to a new shape with zeros.
+
+    Args:
+        tensor (torch.Tensor): The original tensor to be padded.
+        new_shape (List[int]): The desired shape of the padded tensor.
+
+    Returns:
+        torch.Tensor: A new tensor padded with zeros to the specified shape.
+
+    Note:
+        If the new shape is smaller than the original tensor in any dimension,
+        the original tensor will be truncated in that dimension.
+    """
+    if any([new_shape[i] < tensor.shape[i] for i in range(len(new_shape))]):
+        raise ValueError("The new shape must be larger than the original tensor in all dimensions")
+
+    if len(new_shape) != len(tensor.shape):
+        raise ValueError("The new shape must have the same number of dimensions as the original tensor")
+
+    # Create a new tensor filled with zeros
+    padded_tensor = torch.zeros(new_shape, dtype=tensor.dtype, device=tensor.device)
+
+    # Create slicing tuples for both tensors
+    orig_slices = tuple(slice(0, dim) for dim in tensor.shape)
+    new_slices = tuple(slice(0, dim) for dim in tensor.shape)
+
+    # Copy the original tensor into the new tensor
+    padded_tensor[new_slices] = tensor[orig_slices]
+
+    return padded_tensor
+
 def calculate_weight(patches, weight, key, intermediate_dtype=torch.float32):
     for p in patches:
         strength = p[0]
@@ -375,12 +409,18 @@ def calculate_weight(patches, weight, key, intermediate_dtype=torch.float32):
             v = v[1]
 
         if patch_type == "diff":
-            w1 = v[0]
+            diff: torch.Tensor = v[0]
+            # An extra flag to pad the weight if the diff's shape is larger than the weight
+            do_pad_weight = len(v) > 1 and v[1]['pad_weight']
+            if do_pad_weight and diff.shape != weight.shape:
+                logging.info("Pad weight {} from {} to shape: {}".format(key, weight.shape, diff.shape))
+                weight = pad_tensor_to_shape(weight, diff.shape)
+
             if strength != 0.0:
-                if w1.shape != weight.shape:
-                    logging.warning("WARNING SHAPE MISMATCH {} WEIGHT NOT MERGED {} != {}".format(key, w1.shape, weight.shape))
+                if diff.shape != weight.shape:
+                    logging.warning("WARNING SHAPE MISMATCH {} WEIGHT NOT MERGED {} != {}".format(key, diff.shape, weight.shape))
                 else:
-                    weight += function(strength * comfy.model_management.cast_to_device(w1, weight.device, weight.dtype))
+                    weight += function(strength * comfy.model_management.cast_to_device(diff, weight.device, weight.dtype))
         elif patch_type == "lora": #lora/locon
             mat1 = comfy.model_management.cast_to_device(v[0], weight.device, intermediate_dtype)
             mat2 = comfy.model_management.cast_to_device(v[1], weight.device, intermediate_dtype)