https://gcc.gnu.org/bugzilla/show_bug.cgi?id=115307
--- Comment #7 from Joseph S. Myers <jsm28 at gcc dot gnu.org> --- Note the difference between __builtin_isinf (C standard semantics, returns unspecified nonzero value for an infinity) and __builtin_isinf_sign (stricter semantics returning 1 for +Inf and -1 for -Inf).
