https://gcc.gnu.org/bugzilla/show_bug.cgi?id=99637
Jakub Jelinek <jakub at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |jakub at gcc dot gnu.org --- Comment #1 from Jakub Jelinek <jakub at gcc dot gnu.org> --- The result in your case doesn't have any padding bits, but the source has and some value bits of the result need to be initialized from those padding bits.