https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104288
--- Comment #17 from Andrew Pinski <pinskia at gcc dot gnu.org> --- (In reply to Christian Prochaska from comment #16) > (In reply to Andrew Pinski from comment #14) > > > > There was a deferencing of myself before: > > Nova::Utcb &utcb = *(Nova::Utcb *)myself->utcb(); > > I see. The 'Thread::utcb()' function handles the null pointer case > internally with a 'this == 0' check and a local > '-fno-delete-null-pointer-checks' attribute: > > https://github.com/genodelabs/genode/blob/ > a84af9a9606450471b8038a35f9b55057efa0850/repos/base-nova/src/lib/base/stack. > cc#L110 > > So, the elimination of the 'myself' null pointer check is basically a result > of undefined behavior with the 'Thread::utcb()' function? That only handles one side of where it is undefined. Newer GCC uses it as being undefined even on the calling side. So you need to use -fno-delete-null-pointer-checks really on the command line or better yet fixes all of the places which use ->utcb() .
