https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65369
--- Comment #21 from Jakub Jelinek <jakub at gcc dot gnu.org> --- Looking at https://git.lysator.liu.se/nettle/nettle/blob/master/md4.c I see there: bit_count = (ctx->count << 9) | (ctx->index << 3); data[MD4_DATA_LENGTH-2] = bit_count; data[MD4_DATA_LENGTH-1] = bit_count >> 32; and thus it initializes everything.