Allow zero-element tensors for shared inputs. (#13935)

Summary:
Pull Request resolved: #13935

Adds support for the case where method inputs are zero-element. Similar to #13623, but adds support for shared input instead.

Reviewed By: JacobSzwejbka, DrJessop

Differential Revision: D81653487

Author: hsharma35

runtime/core/exec_aten/util/tensor_util_portable.cpp

@@ -147,6 +147,12 @@ Error share_tensor_data(
       t_dst.nbytes(),
       t_src.nbytes());
 
+  if (t_src.numel() == 0) {
+    // Note that t_dst is assumed to already be resized.
+    // If the t_src is empty, no need to update the data_ptr for t_dst.
+    return Error::Ok;
+  }
+
   ET_CHECK_OR_RETURN_ERROR(
       t_src.mutable_data_ptr() != nullptr,
       InvalidArgument,