fix docstring for group barrier; and add todo for group barrier overload

Author: adarshyoga

numba_dpex/experimental/_kernel_dpcpp_spirv_overloads/_group_barrier_overloads.py

@@ -120,6 +120,11 @@ def ol_group_barrier(group, fence_scope=MemoryScope.WORK_GROUP):
         )
 
     mem_scope = _get_memory_scope(fence_scope)
+    # TODO: exec_scope needs to be determined based on
+    # group argument. If group refers to a work_group then,
+    # exec_scope is MemoryScope.WORK_GROUP.
+    # If group is sub_group then, exec_scope needs to be
+    # MemoryScope.SUB_GROUP
     exec_scope = get_scope(MemoryScope.WORK_GROUP.value)
     spirv_memory_semantics_mask = get_memory_semantics_mask(
         MemoryOrder.SEQ_CST.value

numba_dpex/kernel_api/barrier.py

@@ -15,11 +15,7 @@ def group_barrier(group: Group, fence_scope=MemoryScope.WORK_GROUP):
     The function is modeled after the ``sycl::group_barrier`` function. It
     synchronizes work within a group of work items. All the work-items
     of the group must execute the barrier construct before any work-item
-    continues execution beyond the barrier. However, unlike
-    ``sycl::group_barrier`` the numba_dpex function implicitly synchronizes at
-    the level of a work group and does not allow specifying the group as an
-    argument. The :func:`sub_group_barrier` function should be used if
-    synchronization has to be performed only across a sub-group.
+    continues execution beyond the barrier.
 
     The ``group_barrier`` performs mem-fence operations ensuring that memory
     accesses issued before the barrier are not re-ordered with those issued