The following piece of code in trnman.c:

345   trn->min_read_from=  active_list_min.next->trid;
  ...
351   active_list_max.prev= trn->prev->next= trn;
352   trid_min_read_from= active_list_min.next->min_read_from;

on 345 gcc stores active_list_min.next in %ebx
(and trn->min_read_from=[%ebx]->trid)
and on 352 it does trid_min_read_from= [%ebx]->min_read_from;
BUT active_list_min.next was changed on the line 351.
gcc doesn't notice it and continues to use the cached value.