https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104436
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- DECL_BY_REFERENCE on the PARM_DECL tells you that indeed (not on the fndecl).
rguenth at gcc dot gnu.org via Gcc-bugs Tue, 08 Feb 2022 01:10:18 -0800
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104436
--- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- DECL_BY_REFERENCE on the PARM_DECL tells you that indeed (not on the fndecl).