[Models] Improve iteration over layers (#19497)

Signed-off-by: Lukas Geiger <lukas.geiger94@gmail.com>

vllm/model_executor/models/gpt_bigcode.py

@@ -21,6 +21,7 @@
 # limitations under the License.
 """Inference-only GPTBigCode model compatible with HuggingFace weights."""
 from collections.abc import Iterable
+from itertools import islice
 from typing import Optional, Union
 
 import torch
@@ -246,7 +247,7 @@ class GPTBigCodeModel(nn.Module):
         else:
             hidden_states = intermediate_tensors["hidden_states"]
 
-        for layer in self.h[self.start_layer:self.end_layer]:
+        for layer in islice(self.h, self.start_layer, self.end_layer):
             hidden_states = layer(hidden_states)
 
         if not get_pp_group().is_last_rank: