https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108517
--- Comment #7 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Or perhaps when considering the constprop see that for __first_5(D) being 0B there would be pointer arithmetics on NULL (the __first_5(D) p+ 16) and so would invoke UB or likely invoke UB and so not worth constant propagation.
