This is the Ada front-end (in fact gigi) part.

ada/
	* gcc-interface/gigi.h (set_reverse_storage_order_on_pad_type): Declare
	* gcc-interface/decl.c (gnat_to_gnu_entity) <discrete_type>: Set the
	storage order on the enclosing record for a packed array type.
	<E_Array_Type>: Set the storage order.
	<E_Array_Subtype>: Likewise.
	<E_Record_Type>: Likewise.
	<E_Record_Subtype>: Likewise.
	(gnat_to_gnu_component_type): Set the reverse storage order on a padded
	type built for a non-bit-packed array.
	(gnat_to_gnu_field): Likewise.
	(components_to_record): Deal with TYPE_REVERSE_STORAGE_ORDER.
	* gcc-interface/utils.c (make_packable_type): Likewise.
	(pad_type_hasher::equal): Likewise.
	(gnat_types_compatible_p): Likewise.
	(unchecked_convert): Likewise.
	(set_reverse_storage_order_on_pad_type): New public function.
	* gcc-interface/trans.c (Attribute_to_gnu): Adjust call to
	get_inner_reference.
	* gcc-interface/utils2.c (build_unary_op): Likewise.
	(gnat_build_constructor): Deal with TYPE_REVERSE_STORAGE_ORDER.
	(gnat_rewrite_reference): Propagate the REF_REVERSE_STORAGE_ORDER flag.

 decl.c   |   49 +++++++++++++++++++++++++++++++++---
 gigi.h   |    3 ++
 trans.c  |    4 +--
 utils.c  |   84 +++++++++++++++++++++++++++++++++++++++++++++++++++----------
 utils2.c |   15 +++++++----
 5 files changed, 131 insertions(+), 24 deletions(-)

-- 
Eric Botcazou