Fixing slice scatter and select scatter decomposition (#3093)

Author: apbose

py/torch_tensorrt/dynamo/lowering/_decompositions.py

@@ -190,6 +190,7 @@ def slice_scatter_decomposition(
     step: Optional[int] = None,
 ) -> torch.Tensor:
     dim_size = input_tensor.shape[dim]
+    device_input_tensor = input_tensor.device
     start = get_positive_dim(start, input_tensor.shape[dim])
     if end is None:
         end = dim_size
@@ -216,7 +217,8 @@ def slice_scatter_decomposition(
             index_tensor_shape.append(src_each_dim)
     for index in range(start, end, step):
         cat_tensors.append(index * torch.ones(index_tensor_shape, dtype=torch.int64))
-    index_tensor = torch.stack(cat_tensors, dim).to(input_tensor.device)
+    index_tensor = torch.stack(cat_tensors, dim)
+    index_tensor = index_tensor.to(device_input_tensor)
     index_tensor_64 = index_tensor.to(torch.int64)
     output_tensor = torch.scatter(input_tensor, dim, index_tensor_64, src_tensor)
     return output_tensor