-
-
-/*
- __ _ __ __
- (_ __ o _ | \/ |_
- __)|_| | \_/ | \_/(/_ |_/\__|__
-
- The following stuff implements a facility that automatically patches
- registered ir_node pointers to the new node when a dead node elimination occurs.
-
-
- Warning: This is considered a hack - try hard to avoid this!
-*/
-
-struct _survive_dce_t {
- struct obstack obst;
- pmap *places;
- pmap *new_places;
- hook_entry_t dead_node_elim;
- hook_entry_t dead_node_elim_subst;
-};
-
-typedef struct _survive_dce_list_t {
- struct _survive_dce_list_t *next;
- ir_node **place;
-} survive_dce_list_t;
-
-static void dead_node_hook(void *context, ir_graph *irg, int start)
-{
- survive_dce_t *sd = context;
- (void) irg;
-
- /* Create a new map before the dead node elimination is performed. */
- if (start) {
- sd->new_places = pmap_create_ex(pmap_count(sd->places));
- } else {
- /* Patch back all nodes if dead node elimination is over and something is to be done. */
- pmap_destroy(sd->places);
- sd->places = sd->new_places;
- sd->new_places = NULL;
- }
-}
-
-/**
- * Hook called when dead node elimination replaces old by nw.
- */
-static void dead_node_subst_hook(void *context, ir_graph *irg, ir_node *old, ir_node *nw)
-{
- survive_dce_t *sd = context;
- survive_dce_list_t *list = pmap_get(sd->places, old);
- (void) irg;
-
- /* If the node is to be patched back, write the new address to all registered locations. */
- if (list) {
- survive_dce_list_t *p;
-
- for (p = list; p; p = p->next)
- *(p->place) = nw;
-
- pmap_insert(sd->new_places, nw, list);
- }
-}
-
-/**
- * Make a new Survive DCE environment.
- */
-survive_dce_t *new_survive_dce(void)
-{
- survive_dce_t *res = XMALLOC(survive_dce_t);
- obstack_init(&res->obst);
- res->places = pmap_create();
- res->new_places = NULL;
-
- res->dead_node_elim.hook._hook_dead_node_elim = dead_node_hook;
- res->dead_node_elim.context = res;
- res->dead_node_elim.next = NULL;
-
- res->dead_node_elim_subst.hook._hook_dead_node_elim_subst = dead_node_subst_hook;
- res->dead_node_elim_subst.context = res;
- res->dead_node_elim_subst.next = NULL;
-
- register_hook(hook_dead_node_elim, &res->dead_node_elim);
- register_hook(hook_dead_node_elim_subst, &res->dead_node_elim_subst);
- return res;
-}
-
-/**
- * Free a Survive DCE environment.
- */
-void free_survive_dce(survive_dce_t *sd)
-{
- obstack_free(&sd->obst, NULL);
- pmap_destroy(sd->places);
- unregister_hook(hook_dead_node_elim, &sd->dead_node_elim);
- unregister_hook(hook_dead_node_elim_subst, &sd->dead_node_elim_subst);
- xfree(sd);
-}
-
-/**
- * Register a node pointer to be patched upon DCE.
- * When DCE occurs, the node pointer specified by @p place will be
- * patched to the new address of the node it is pointing to.
- *
- * @param sd The Survive DCE environment.
- * @param place The address of the node pointer.
- */
-void survive_dce_register_irn(survive_dce_t *sd, ir_node **place)
-{
- if (*place != NULL) {
- ir_node *irn = *place;
- survive_dce_list_t *curr = pmap_get(sd->places, irn);
- survive_dce_list_t *nw = OALLOC(&sd->obst, survive_dce_list_t);
-
- nw->next = curr;
- nw->place = place;
-
- pmap_insert(sd->places, irn, nw);
- }
-}