Fix qwen2 1.5B NPU load error (#12049)

python/llm/src/ipex_llm/transformers/npu_model.py

@@ -202,9 +202,6 @@ class _BaseAutoModelClass:
     @classmethod
     @patch("transformers.dynamic_module_utils.get_imports", patch_flash_attn_import)
     def load_low_bit(cls, pretrained_model_name_or_path: str, *model_args, **kwargs):
-        if kwargs.pop("torch_dtype", None) not in [None, "auto", torch.float]:
-            warnings.warn("`torch_dtype` will be ignored, `torch.float` will be used")
-
         # ignore following arguments
         ignore_argument(kwargs, "model_hub")
         ignore_argument(kwargs, "lightweight_bmm")
@@ -402,6 +399,10 @@ class _BaseAutoModelClass:
         if dtype_orig is not None:
             torch.set_default_dtype(dtype_orig)
 
+        # set tie_word_embeddings to False to avoid possible lm_head error
+        if hasattr(model.config, "tie_word_embeddings"):
+            model.config.tie_word_embeddings = False
+
         (
             model,
             missing_keys,