https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122483
--- Comment #23 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Flags on what exactly? The TREE_LIST which has the attribute name and value is recreated quite often when merging attributes etc., so putting flags on there isn't stable. Flags could be put on the TREE_VALUE of it (which is a TREE_LIST too), as is done e.g. for C++ annotations already - ATTR_UNIQUE_VALUE_P. But perhaps the aarch64 attributes don't have values or don't have them always? Or it could be put on the TREE_PURPOSE of it (but then it would work only for the scoped attributes, so guess fine for arm::something attributes, but not for something, the latter has TREE_PURPOSE just the IDENTIFIER_NODE and it is a bad idea to put flags on IDENTIFIER_NODE.
