chore: import upstream snapshot with attribution

python/mlc_llm/model/model_utils.py

@@ -0,0 +1,14 @@
+"""Utilities shared across model definitions."""
+
+from tvm import te
+from tvm.relax.frontend.nn import Tensor, op
+
+
+def index_last_token(x: Tensor) -> Tensor:
+    """Select the last token while preserving the historical `index` TE op shape/name."""
+
+    def _index(x: te.Tensor):
+        b, s, d = x.shape
+        return te.compute((b, 1, d), lambda i, _, k: x[i, s - 1, k], name="index")
+
+    return op.tensor_expr_op(_index, name_hint="index", args=[x])