CL util to convert models to fp16 before upload (#5953)

examples/seq2seq/convert_model_to_fp16.py

+from typing import Union
+
+import fire
+import torch
+from tqdm import tqdm
+
+
+def convert(src_path: str, map_location: str = "cpu", save_path: Union[str, None] = None) -> None:
+    """Convert a pytorch_model.bin or model.pt file to torch.float16 for faster downloads, less disk space."""
+    state_dict = torch.load(src_path, map_location=map_location)
+    for k, v in tqdm(state_dict.items()):
+        if not isinstance(v, torch.Tensor):
+            raise TypeError("FP16 conversion only works on paths that are saved state dics, like pytorch_model.bin")
+        state_dict[k] = v.half()
+    if save_path is None:  # overwrite src_path
+        save_path = src_path
+    torch.save(state_dict, save_path)
+
+
+if __name__ == "__main__":
+    fire.Fire(convert)