remove _shard_tensor() call (#111687)

Co-authored-by: Andrey Talman <atalman@fb.com>

torch/distributed/checkpoint/optimizer.py

@@ -22,6 +22,8 @@
     TensorStorageMetadata,
     ChunkStorageMetadata,
 )
+from torch.distributed.distributed_c10d import _get_default_group
+from torch.distributed.fsdp._shard_utils import _create_chunk_sharded_tensor
 from torch.distributed.checkpoint.planner_helpers import (
     create_read_items_for_chunk_list,
     _create_read_items,
@@ -32,7 +34,7 @@
 from torch.distributed.checkpoint.default_planner import (
     DefaultLoadPlanner,
 )
-from torch.distributed._shard.api import _shard_tensor
+
 from torch.distributed.checkpoint.planner import LoadPlanner
 
 from torch.distributed.checkpoint._nested_dict import unflatten_state_dict
@@ -293,8 +295,12 @@ def load_sharded_optimizer_state_dict(
         if value.size.numel() == 1:
             state_dict[key] = _alloc_tensor(value.properties, value.size, dp_pg_device_type)
         elif dp_pg is None:
-            state_dict[key] = _shard_tensor(
-                _alloc_tensor(value.properties, value.size, dp_pg_device_type), sharding_spec
+            state_dict[key] = _create_chunk_sharded_tensor(
+                _alloc_tensor(value.properties, value.size, dp_pg_device_type),
+                rank=dist.get_rank(),
+                world_size=dist.get_world_size(),
+                num_devices_per_node=device_module.device_count(),
+                pg=_get_default_group(),
             )
         else:
             spec_key = key_path[2]