T5 test and target device fixes (huggingface#40313)

* Fix cache setup related issues

* Fix target-device-related issues

* Ruff

* Address review comments

Author: ahadnagy

src/transformers/integrations/executorch.py

@@ -820,11 +820,15 @@ def __init__(self, model, max_static_cache_length, batch_size):
         self.lm_head = model.lm_head
         self.config = model.config
 
+        # Detect the device of the exported models by checking a parameter
+        # We'll use the model's device as the target device
+        model_device = next(model.parameters()).device
+
         # Initialize static cache for decoder and DynamicCache for encoder
         self.static_cache = StaticCache(config=self.config, max_cache_len=max_static_cache_length)
         head_dim = getattr(self.config, "head_dim", self.config.hidden_size // self.config.num_attention_heads)
         num_heads = getattr(self.config, "num_key_value_heads", self.config.num_attention_heads)
-        self.static_cache.early_initialization(batch_size, num_heads, head_dim, torch.float32, "cpu")
+        self.static_cache.early_initialization(batch_size, num_heads, head_dim, torch.float32, model_device)
         self.cache = EncoderDecoderCache(self.static_cache, DynamicCache())
 
         register_dynamic_cache_export_support()
@@ -887,16 +891,22 @@ def _export_encoder(self, encoder_input_ids):
         return exported_encoder
 
     def _export_decoder(self, decoder_input_ids, encoder_hidden_states, cache_position):
+        target_device = self.full_model.device
         wrapped_decoder = (
             Seq2SeqLMDecoderExportableModuleWithStaticCache(
                 model=self.full_model,
-                max_static_cache_length=self.generation_config.cache_config.max_cache_len,
-                batch_size=self.generation_config.cache_config.batch_size,
+                max_static_cache_length=self.generation_config.cache_config.get("max_cache_len"),
+                batch_size=self.generation_config.cache_config.get("batch_size"),
             )
-            .to("cpu")
+            .to(target_device)
             .eval()
         )
 
+        # Move input tensors to the same device as the wrapped decoder
+        decoder_input_ids = decoder_input_ids.to(target_device)
+        encoder_hidden_states = encoder_hidden_states.to(target_device)
+        cache_position = cache_position.to(target_device)
+
         # Define dynamic dimension for encoder output sequence length
         encoder_seq_len_dim = torch.export.Dim("encoder_hidden_seq_length", max=self.max_hidden_seq_length)
 
@@ -934,7 +944,7 @@ def export(self, encoder_input_ids=None, decoder_input_ids=None, encoder_hidden_
             encoder_hidden_states
             if encoder_hidden_states is not None
             else torch.zeros(
-                (self.generation_config.cache_config.batch_size, 10, self.config.d_model),
+                (self.generation_config.cache_config.get("batch_size"), 10, self.config.d_model),
                 dtype=torch.float32,
                 device=device,
             )
@@ -949,26 +959,32 @@ def export(self, encoder_input_ids=None, decoder_input_ids=None, encoder_hidden_
 
     def generate(self, prompt_token_ids, max_new_tokens):
         with torch.no_grad():
+            model_device = self.full_model.device
+
+            # Move input to the model's device if it's on a different device
+            if prompt_token_ids.device != model_device:
+                prompt_token_ids = prompt_token_ids.to(model_device)
+
             # Run encoder
             encoder_output = self.exported_encoder.module()(prompt_token_ids)
 
-            # Initialize with start token (0 for T5)
-            decoder_input_ids = torch.tensor([[0]], dtype=torch.long)
+            # Initialize with start token (0 for T5) on the correct device
+            decoder_input_ids = torch.tensor([[0]], dtype=torch.long, device=model_device)
             generated_ids = [0]
 
             # Generate tokens one by one
             for i in range(max_new_tokens - 1):
                 # Run decoder for next token prediction
                 logits = self.exported_decoder.module()(
-                    decoder_input_ids, encoder_output, torch.tensor([i], dtype=torch.long)
+                    decoder_input_ids, encoder_output, torch.tensor([i], dtype=torch.long, device=model_device)
                 )
 
                 # Get next token
                 next_token = torch.argmax(logits[:, -1, :], dim=-1).item()
                 generated_ids.append(next_token)
 
-                # Update input for next iteration
-                decoder_input_ids = torch.tensor([[next_token]], dtype=torch.long)
+                # Update input for next iteration on the correct device
+                decoder_input_ids = torch.tensor([[next_token]], dtype=torch.long, device=model_device)
 
                 # Check if EOS token
                 if next_token == self.config.eos_token_id: