nsz Git - libfirm/blob - ir/common/survive_dce.c

   1
   2 #include "pmap.h"
   3
   4 #include "irnode_t.h"
   5 #include "irhooks.h"
   6 #include "irgwalk.h"
   7
   8 #include "survive_dce.h"
   9
  10 struct _survive_dce_t {
  11         pmap *places;
  12         pmap *new_places;
  13         hook_entry_t dead_node_elim;
  14         hook_entry_t dead_node_elim_subst;
  15 };
  16
  17 static void dead_node_hook(void *context, ir_graph *irg, int start)
  18 {
  19         survive_dce_t *sd = context;
  20
  21         /* Create a new map before the dead node elimination is performed. */
  22         if(start) {
  23                 sd->new_places = pmap_create_ex(pmap_count(sd->places));
  24         }
  25
  26         /* Patch back all nodes if dead node elimination is over and something is to be done. */
  27         else {
  28                 pmap_destroy(sd->places);
  29                 sd->places     = sd->new_places;
  30                 sd->new_places = NULL;
  31         }
  32 }
  33
  34 static void dead_node_subst_hook(void *context, ir_graph *irg, ir_node *old, ir_node *nw)
  35 {
  36         survive_dce_t *sd = context;
  37         ir_node **place    = (ir_node **) pmap_get(sd->places, old);
  38
  39         /* If the node is to be patched back, do it. */
  40         if(place) {
  41                 *place = nw;
  42                 pmap_insert(sd->new_places, nw, (void *) place);
  43         }
  44 }
  45
  46 survive_dce_t *new_survive_dce(void)
  47 {
  48         survive_dce_t *res = xmalloc(sizeof(res[0]));
  49         res->places     = pmap_create();
  50         res->new_places = NULL;
  51
  52         res->dead_node_elim.hook._hook_dead_node_elim = dead_node_hook;
  53         res->dead_node_elim.context                   = res;
  54         res->dead_node_elim.next                      = NULL;
  55
  56         res->dead_node_elim_subst.hook._hook_dead_node_elim_subst = dead_node_subst_hook;
  57         res->dead_node_elim_subst.context = res;
  58         res->dead_node_elim_subst.next    = NULL;
  59
  60         register_hook(hook_dead_node_elim, &res->dead_node_elim);
  61         register_hook(hook_dead_node_elim_subst, &res->dead_node_elim_subst);
  62         return res;
  63 }
  64
  65 void free_survive_dce(survive_dce_t *sd)
  66 {
  67         pmap_destroy(sd->places);
  68         unregister_hook(hook_dead_node_elim, &sd->dead_node_elim);
  69         unregister_hook(hook_dead_node_elim_subst, &sd->dead_node_elim_subst);
  70         free(sd);
  71 }
  72
  73 void survive_dce_register_irn(survive_dce_t *sd, ir_node **place)
  74 {
  75         pmap_insert(sd->places, *place, (void *) place);
  76 }