-
-
-#if 0
-/* Dominator Tree */
-
-/* temporary type used while constructing the dominator tree. */
-typedef struct tmp_dom_info tmp_dom_info;
-struct tmp_dom_info {
- ir_node *region;
-
- tmp_dom_info *semi; /* semidominator */
- tmp_dom_info *parent;
- tmp_dom_info *label; /* used for LINK and EVAL */
- tmp_dom_info *ancestor; /* used for LINK and EVAL */
- tmp_dom_info *dom; /* After step 3, if the semidominator
- of w is its immediate dominator, then w->dom is the immediate
- dominator of w. Otherwise w->dom is a vertex v whose number is
- smaller than w and whose immediate dominator is also w's immediate
- dominator. After step 4, w->dom is the immediate dominator of w. */
- tmp_dom_info *bucket; /* set of vertices with same semidominator */
-};
-
-static int
-dom_count_regions (ir_node *n)
-{
- int i, count = 1;
-
- n->visit = ir_visited;
-
- for (i = IR_ARITY (n); i > 0; --i) {
- ir_node *pr = prev_region (n, i);
- if (pr && pr->visit != ir_visited) {
- count += dom_count_regions (pr);
- }
- }
- return count;
-}
-
-struct dt_desc { tmp_dom_info *dt; int used;};
-
-static void
-dom_setup (ir_node *n, tmp_dom_info *parent, struct dt_desc *dt_desc)
-{
- tmp_dom_info *dt = &dt_desc->dt[dt_desc->used];
- int i;
-
- if (n->visit == ir_visited) return;
- n->visit = ir_visited;
-
- assert (IR_CFG_NODE (n));
-
- n->data.r.pre_num = dt_desc->used;
- dt->semi = dt;
- dt->label = dt;
- dt->ancestor = NULL;
- dt->bucket = NULL;
- dt->parent = parent;
- dt->region = n;
- ++(dt_desc->used);
-
- for (i = 0; i < n->data.r.cfg_outs; ++i) {
- dom_setup (n->data.r.cfg_out[i], dt, dt_desc);
- }
-}
-
-static void
-dom_compress (tmp_dom_info *v)
-{
- assert (v->ancestor);
- if (v->ancestor->ancestor) {
- dom_compress (v->ancestor);
- if (v->ancestor->label->semi < v->label->semi) {
- v->label = v->ancestor->label;
- }
- v->ancestor = v->ancestor->ancestor;
- }
-}
-
-/* if V is a root, return v, else return the vertex u, not being the
- root, with minimum u->semi on the path from v to its root. */
-static tmp_dom_info*
-dom_eval (tmp_dom_info *v)
-{
- if (!v->ancestor) return v;
- dom_compress (v);
- return v->label;
-}
-
-/* make V W's ancestor */
-static void
-dom_link (tmp_dom_info *v, tmp_dom_info *w)
-{
- w->ancestor = v;
-}
-
-void
-irg_gen_idom (ir_graph *irg)
-{
- int regions, i;
- tmp_dom_info *dt;
- struct dt_desc dt_desc;
-
- if (!(irg->state & irgs_has_CFG)) irg_gen_out (irg);
-
- ++ir_visited;
- regions = 0;
- /* walk all the artificially kept alive parts of the CFG instead of
- the CFG beginning from the Start just for fun and safety */
- keep_alives_in_arr (irg);
- for (i = ARR_LEN (irg->keep.alive) - 1; i >= 0; --i)
- if ( IR_CFG_NODE (irg->keep.alive[i])
- && irg->keep.alive[i]->visit != ir_visited)
- regions += dom_count_regions (irg->keep.alive[i]);
-
- dt = alloca ((regions+1) * sizeof (tmp_dom_info));
- memset (dt, 0, (regions+1) * sizeof (tmp_dom_info));
-
- /* Step 1 */
- dt_desc.dt = dt;
- dt_desc.used = 1;
- ++ir_visited;
- dom_setup (irg->start, NULL, &dt_desc);
-
- /* This assert will fail, if not all Regions are reachable by
- walking the CFG starting from Start, that is when there is
- [control] dead code, violating the single entry precondition of
- this algorithm. */
- assert (dt_desc.used == regions + 1);
-
- for (i = regions; i > 1; --i) {
- tmp_dom_info *w = &dt[i];
- tmp_dom_info *v;
- int j, r_ins;
-
- /* Step 2 */
- r_ins = IR_ARITY (w->region);
- for (j = 1; j <= r_ins; ++j) {
- ir_node *prev = prev_region (w->region, j);
- tmp_dom_info *u;
-
- if (!prev) continue; /* control-dead */
-
- u = dom_eval (&dt[prev->data.r.pre_num]);
- if (u->semi < w->semi) w->semi = u->semi;
- }
- /* Add w to w->semi's bucket. w is in exactly one bucket, so
- buckets can ben implemented as linked lists. */
- w->bucket = w->semi->bucket;
- w->semi->bucket = w;
-
- dom_link (w->parent, w);
-
- /* Step 3 */
- while ((v = w->parent->bucket)) {
- tmp_dom_info *u;
- /* remove v from w->parent->bucket */
- w->parent->bucket = v->bucket;
- v->bucket = NULL;
-
- u = dom_eval (v);
- v->dom = u->semi < v->semi ? u : w->parent;
- }
- }
- /* Step 4 */
- dt[1].dom = NULL;
- dt[1].region->data.r.idom = NULL;
- dt[1].region->data.r.dom_depth = 1;
- for (i = 2; i <= regions; ++i) {
- tmp_dom_info *w = &dt[i];
-
- if (w->dom != w->semi) w->dom = w->dom->dom;
- w->region->data.r.idom = w->dom->region;
- w->region->data.r.dom_depth = w->dom->region->data.r.dom_depth + 1;
- }
- current_ir_graph = sirg;
-}
-
-#endif