Safetensors loading in "convert_diffusers_to_original_stable_diffusion" (#2054)

* Safetensors loading in "convert_diffusers_to_original_stable_diffusion"

Adds diffusers format saftetensors loading support

* Fix import sort order: convert_diffusers_to_original_stable_diffusion.py
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

scripts/convert_diffusers_to_original_stable_diffusion.py

@@ -8,7 +8,7 @@ import re
 
 import torch
 
-from safetensors.torch import save_file
+from safetensors.torch import load_file, save_file
 
 
 # =================#
@@ -278,23 +278,38 @@ if __name__ == "__main__":
 
     assert args.checkpoint_path is not None, "Must provide a checkpoint path!"
 
+    # Path for safetensors
+    unet_path = osp.join(args.model_path, "unet", "diffusion_pytorch_model.safetensors")
+    vae_path = osp.join(args.model_path, "vae", "diffusion_pytorch_model.safetensors")
+    text_enc_path = osp.join(args.model_path, "text_encoder", "model.safetensors")
+
+    # Load models from safetensors if it exists, if it doesn't pytorch
+    if osp.exists(unet_path):
+        unet_state_dict = load_file(unet_path, device="cpu")
+    else:
         unet_path = osp.join(args.model_path, "unet", "diffusion_pytorch_model.bin")
+        unet_state_dict = torch.load(unet_path, map_location="cpu")
+
+    if osp.exists(vae_path):
+        vae_state_dict = load_file(vae_path, device="cpu")
+    else:
         vae_path = osp.join(args.model_path, "vae", "diffusion_pytorch_model.bin")
+        vae_state_dict = torch.load(vae_path, map_location="cpu")
+
+    if osp.exists(text_enc_path):
+        text_enc_dict = load_file(text_enc_path, device="cpu")
+    else:
         text_enc_path = osp.join(args.model_path, "text_encoder", "pytorch_model.bin")
+        text_enc_dict = torch.load(text_enc_path, map_location="cpu")
 
     # Convert the UNet model
-    unet_state_dict = torch.load(unet_path, map_location="cpu")
     unet_state_dict = convert_unet_state_dict(unet_state_dict)
     unet_state_dict = {"model.diffusion_model." + k: v for k, v in unet_state_dict.items()}
 
     # Convert the VAE model
-    vae_state_dict = torch.load(vae_path, map_location="cpu")
     vae_state_dict = convert_vae_state_dict(vae_state_dict)
     vae_state_dict = {"first_stage_model." + k: v for k, v in vae_state_dict.items()}
 
-    # Convert the text encoder model
-    text_enc_dict = torch.load(text_enc_path, map_location="cpu")
-
     # Easiest way to identify v2.0 model seems to be that the text encoder (OpenCLIP) is deeper
     is_v20_model = "text_model.encoder.layers.22.layer_norm2.bias" in text_enc_dict