GPTQ export w/a (huggingface#451)

* Patch the modules in order to export GPTQ models on CPU

* Style

optimum/intel/openvino/modeling_decoder.py

@@ -227,6 +227,34 @@ def _from_transformers(
             if use_cache:
                 task = task + "-with-past"
 
+        # Patch the modules to export of GPTQ models w/o GPU
+        do_gptq_patching = False
+        config_dict = config.to_dict()
+        quantization_config = config_dict.get("quantization_config", None)
+        do_gptq_patching = quantization_config and quantization_config["quant_method"] == "gptq"
+        if do_gptq_patching:
+            torch.set_default_dtype(torch.float32)
+            orig_cuda_check = torch.cuda.is_available
+            torch.cuda.is_available = lambda: True
+
+            from optimum.gptq import GPTQQuantizer
+
+            orig_post_init_model = GPTQQuantizer.post_init_model
+
+            def post_init_model(self, model):
+                from auto_gptq import exllama_set_max_input_length
+
+                class StoreAttr(object):
+                    pass
+
+                model.quantize_config = StoreAttr()
+                model.quantize_config.desc_act = self.desc_act
+                if self.desc_act and not self.disable_exllama and self.max_input_length is not None:
+                    model = exllama_set_max_input_length(model, self.max_input_length)
+                return model
+
+            GPTQQuantizer.post_init_model = post_init_model
+
         main_export(
             model_name_or_path=model_id,
             output=save_dir_path,
@@ -238,10 +266,14 @@ def _from_transformers(
             local_files_only=local_files_only,
             force_download=force_download,
             trust_remote_code=trust_remote_code,
-            model_kwargs=kwargs,
             int8=load_in_8bit,
         )
 
+        # Unpatch modules after GPTQ export
+        if do_gptq_patching:
+            torch.cuda.is_available = orig_cuda_check
+            GPTQQuantizer.post_init_model = orig_post_init_model
+
         config.is_decoder = True
         config.is_encoder_decoder = False
         config.save_pretrained(save_dir_path)