Hi Joseph, I've just stumbled over this function in gcc/c-family/c-common.c, which might need adjustment for __float128:
/* Return true iff ALIGN is an integral constant that is a fundamental alignment, as defined by [basic.align] in the c++-11 specifications. That is: [A fundamental alignment is represented by an alignment less than or equal to the greatest alignment supported by the implementation in all contexts, which is equal to alignof(max_align_t)]. */ bool cxx_fundamental_alignment_p (unsigned align) { return (align <= MAX (TYPE_ALIGN (long_long_integer_type_node), TYPE_ALIGN (long_double_type_node))); } Which might need adjustment, if you want to change alignof(max_align_t). Bernd.