https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86285
--- Comment #2 from Peter Bergner <bergner at gcc dot gnu.org> --- When we compile using -mlong-double-64 -mabi=ibmlongdouble, we get what I'd expect: (gdb) ptree type <real_type 0x7ffff58415a8 __ieee128 KF size <integer_cst 0x7ffff5741158 type <integer_type 0x7ffff58400a8 bitsizetype> constant 128> unit-size <integer_cst 0x7ffff5741170 type <integer_type 0x7ffff5840000 sizetype> constant 16> align:128 warn_if_not_align:0 symtab:0 alias-set -1 canonical-type 0x7ffff58415a8 precision:128>