void sqlite3VdbeSetVarmask(Vdbe *v, int iVar){
  assert( iVar>0 );
  assert( (v->db->flags & SQLITE_EnableQPSG)==0 );
  if( iVar>=32 ){
    v->expmask |= 0x80000000;
  }else{
    v->expmask |= ((u32)1 << (iVar-1));
  }
}