avoid upcasting by assigning dtype to noise tensor (#3713)

* avoid upcasting by assigning dtype to noise tensor

* make style

* Update train_unconditional.py

* Update train_unconditional.py

* make style

* add unit test for pickle

* revert change

---------
Co-authored-by: root <root@orttrainingdev8.d32nl1ml4oruzj4qz3bqlggovf.px.internal.cloudapp.net>
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Prathik Rao <prathikrao@microsoft.com@orttrainingdev8.d32nl1ml4oruzj4qz3bqlggovf.px.internal.cloudapp.net>

examples/research_projects/onnxruntime/unconditional_image_generation/train_unconditional.py

@@ -568,7 +568,9 @@ def main(args):
 
             clean_images = batch["input"]
             # Sample noise that we'll add to the images
-            noise = torch.randn(clean_images.shape).to(clean_images.device)
+            noise = torch.randn(
+                clean_images.shape, dtype=(torch.float32 if args.mixed_precision == "no" else torch.float16)
+            ).to(clean_images.device)
             bsz = clean_images.shape[0]
             # Sample a random timestep for each image
             timesteps = torch.randint(

examples/unconditional_image_generation/train_unconditional.py

@@ -557,7 +557,9 @@ def main(args):
 
             clean_images = batch["input"]
             # Sample noise that we'll add to the images
-            noise = torch.randn(clean_images.shape).to(clean_images.device)
+            noise = torch.randn(
+                clean_images.shape, dtype=(torch.float32 if args.mixed_precision == "no" else torch.float16)
+            ).to(clean_images.device)
             bsz = clean_images.shape[0]
             # Sample a random timestep for each image
             timesteps = torch.randint(