3 * File name: ir/ana/irdom.c
4 * Purpose: Construct and access dominator / post dominator tree.
5 * Author: Goetz Lindenmaier
6 * Modified by: Michael Beck, Rubino Geiss
9 * Copyright: (c) 2002-2003 Universitaet Karlsruhe
10 * Licence: This file protected by GPL - GNU GENERAL PUBLIC LICENSE.
26 #include "irgraph_t.h" /* To access state field. */
33 #define get_dom_info(bl) (&(bl)->attr.block.dom)
34 #define get_pdom_info(bl) (&(bl)->attr.block.pdom)
36 /*--------------------------------------------------------------------*/
37 /** Accessing the dominator and post dominator data structures **/
38 /*--------------------------------------------------------------------*/
40 ir_node *get_Block_idom(const ir_node *bl) {
42 if (get_Block_dom_depth(bl) == -1) {
43 /* This block is not reachable from Start */
46 return get_dom_info(bl)->idom;
49 void set_Block_idom(ir_node *bl, ir_node *n) {
50 dom_info *bli = get_dom_info(bl);
52 assert(get_irn_op(bl) == op_Block);
54 /* Set the immediate dominator of bl to n */
58 * If we don't set the root of the dominator tree
59 * Append bl to the dominates queue of n.
62 dom_info *ni = get_dom_info(n);
64 bli->next = ni->first;
69 ir_node *get_Block_ipostdom(const ir_node *bl) {
71 if (get_Block_postdom_depth(bl) == -1) {
72 /* This block is not reachable from Start */
75 return get_pdom_info(bl)->idom;
78 void set_Block_ipostdom(ir_node *bl, ir_node *n) {
79 dom_info *bli = get_pdom_info(bl);
81 assert(get_irn_op(bl) == op_Block);
83 /* Set the immediate post dominator of bl to n */
87 * If we don't set the root of the post dominator tree
88 * Append bl to the post dominates queue of n.
91 dom_info *ni = get_pdom_info(n);
93 bli->next = ni->first;
98 int get_Block_dom_pre_num(const ir_node *bl) {
99 assert(get_irn_op(bl) == op_Block);
100 return get_dom_info(bl)->pre_num;
103 void set_Block_dom_pre_num(ir_node *bl, int num) {
104 assert(get_irn_op(bl) == op_Block);
105 get_dom_info(bl)->pre_num = num;
108 int get_Block_dom_depth(const ir_node *bl) {
109 assert(get_irn_op(bl) == op_Block);
110 return get_dom_info(bl)->dom_depth;
113 void set_Block_dom_depth(ir_node *bl, int depth) {
114 assert(get_irn_op(bl) == op_Block);
115 get_dom_info(bl)->dom_depth = depth;
119 int get_Block_postdom_pre_num(const ir_node *bl) {
120 assert(get_irn_op(bl) == op_Block);
121 return get_pdom_info(bl)->pre_num;
124 void set_Block_postdom_pre_num(ir_node *bl, int num) {
125 assert(get_irn_op(bl) == op_Block);
126 get_pdom_info(bl)->pre_num = num;
129 int get_Block_postdom_depth(const ir_node *bl) {
130 assert(get_irn_op(bl) == op_Block);
131 return get_pdom_info(bl)->dom_depth;
134 void set_Block_postdom_depth(ir_node *bl, int depth) {
135 assert(get_irn_op(bl) == op_Block);
136 get_pdom_info(bl)->dom_depth = depth;
139 unsigned get_Block_dom_tree_pre_num(const ir_node *bl)
141 assert(is_Block(bl));
142 return get_dom_info(bl)->tree_pre_num;
145 unsigned get_Block_dom_max_subtree_pre_num(const ir_node *bl)
147 assert(is_Block(bl));
148 return get_dom_info(bl)->max_subtree_pre_num;
151 unsigned get_Block_pdom_tree_pre_num(const ir_node *bl)
153 assert(is_Block(bl));
154 return get_pdom_info(bl)->tree_pre_num;
157 unsigned get_Block_pdom_max_subtree_pre_num(const ir_node *bl)
159 assert(is_Block(bl));
160 return get_pdom_info(bl)->max_subtree_pre_num;
163 /* Check, if a block dominates another block. */
164 int block_dominates(const ir_node *a, const ir_node *b)
166 const dom_info *ai, *bi;
168 if (is_Block(a) && is_Block(b)) {
169 ai = get_dom_info(a);
170 bi = get_dom_info(b);
171 return bi->tree_pre_num - ai->tree_pre_num
172 <= ai->max_subtree_pre_num - ai->tree_pre_num;
178 /* Returns the smallest common dominator block of two nodes. */
179 ir_node *node_smallest_common_dominator(ir_node *a, ir_node *b)
181 ir_node *bl_a = is_Block(a) ? a : get_nodes_block(a);
182 ir_node *bl_b = is_Block(b) ? b : get_nodes_block(b);
183 ir_node *dom_bl = NULL;
185 /* Check if block of a dominates block of b */
186 if (block_dominates(bl_a, bl_b))
188 /* Check if block of b dominates block of a */
189 else if (block_dominates(bl_b, bl_a))
192 /* walk up dominator tree and search for first block dominating a and b */
194 bl_a = get_Block_idom(bl_a);
196 assert(! is_Bad(bl_a) && "block is dead?");
198 if (block_dominates(bl_a, bl_b))
206 /* Returns the smallest common dominator block of all users of a node. */
207 ir_node *node_users_smallest_common_dominator(ir_node *irn, int handle_phi)
209 int n, j, i = 0, success;
210 ir_node **user_blocks, *dom_bl;
211 const ir_edge_t *edge;
213 assert(! is_Block(irn) && "WRONG USAGE of node_users_smallest_common_dominator");
214 assert(edges_activated(get_irn_irg(irn)) && "need edges activated");
216 n = get_irn_n_edges(irn);
218 /* get array to hold all block of the node users */
219 NEW_ARR_A(ir_node *, user_blocks, n);
220 foreach_out_edge(irn, edge) {
221 ir_node *src = get_edge_src_irn(edge);
223 if (is_Phi(src) && handle_phi) {
224 /* get the corresponding cfg predecessor block if phi handling requested */
225 j = get_edge_src_pos(edge);
226 assert(j >= 0 && "kaputt");
227 user_blocks[i++] = get_Block_cfgpred_block(get_nodes_block(src), j);
230 user_blocks[i++] = is_Block(src) ? src : get_nodes_block(src);
233 assert(i == n && "get_irn_n_edges probably broken");
235 /* in case of only one user: return the block of the user */
237 return user_blocks[0];
240 /* search the smallest block dominating all user blocks */
242 dom_bl = node_smallest_common_dominator(user_blocks[i], user_blocks[i + 1]);
245 /* check if this block dominates all remaining blocks as well */
246 for (j = i + 2; j < n; j++) {
247 if (! block_dominates(dom_bl, user_blocks[j]))
254 /* inherit the dominator block of the first (i + 1) users */
255 user_blocks[++i] = dom_bl;
258 assert(success && "no block found dominating all users");
264 /* Get the first node in the list of nodes dominated by a given block. */
265 ir_node *get_Block_dominated_first(const ir_node *bl)
267 assert(is_Block(bl));
268 return get_dom_info(bl)->first;
271 /* Get the next node in a list of nodes which are dominated by some
273 ir_node *get_Block_dominated_next(const ir_node *bl)
275 assert(is_Block(bl));
276 return get_dom_info(bl)->next;
279 /* Check, if a block post dominates another block. */
280 int block_postdominates(const ir_node *a, const ir_node *b)
282 const dom_info *ai, *bi;
284 if (is_Block(a) && is_Block(b)) {
285 ai = get_pdom_info(a);
286 bi = get_pdom_info(b);
287 return bi->tree_pre_num - ai->tree_pre_num
288 <= ai->max_subtree_pre_num - ai->tree_pre_num;
294 /* Get the first node in the list of nodes post dominated by a given block. */
295 ir_node *get_Block_postdominated_first(const ir_node *bl)
297 assert(is_Block(bl));
298 return get_pdom_info(bl)->first;
301 /* Get the next node in a list of nodes which are post dominated by some
303 ir_node *get_Block_postdominated_next(const ir_node *bl)
305 assert(is_Block(bl));
306 return get_pdom_info(bl)->next;
309 /* Visit all nodes in the dominator subtree of a given node. */
310 void dom_tree_walk(ir_node *bl, irg_walk_func *pre,
311 irg_walk_func *post, void *env)
318 dominates_for_each(bl, p) {
319 dom_tree_walk(p, pre, post, env);
326 /* Visit all nodes in the post dominator subtree of a given node. */
327 void postdom_tree_walk(ir_node *bl, irg_walk_func *pre,
328 irg_walk_func *post, void *env)
335 postdominates_for_each(bl, p) {
336 postdom_tree_walk(p, pre, post, env);
343 /* Walk over the dominator tree of an irg starting at the root. */
344 void dom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
345 irg_walk_func *post, void *env)
347 /* The root of the dominator tree should be the Start block. */
348 ir_node *root = get_irg_start_block(irg);
350 assert(irg->dom_state == dom_consistent
351 && "The dominators of the irg must be consistent");
352 assert(root && "The start block of the graph is NULL?");
353 assert(get_dom_info(root)->idom == NULL
354 && "The start node in the graph must be the root of the dominator tree");
355 dom_tree_walk(root, pre, post, env);
358 /* Walk over the post dominator tree of an irg starting at the root. */
359 void postdom_tree_walk_irg(ir_graph *irg, irg_walk_func *pre,
360 irg_walk_func *post, void *env)
362 /* The root of the dominator tree should be the End block. */
363 ir_node *root = get_irg_end_block(irg);
365 assert(irg->pdom_state == dom_consistent
366 && "The dominators of the irg must be consistent");
367 assert(root && "The end block of the graph is NULL?");
368 assert(get_pdom_info(root)->idom == NULL
369 && "The End block node in the graph must be the root of the post dominator tree");
370 postdom_tree_walk(root, pre, post, env);
374 static void assign_tree_dom_pre_order(ir_node *bl, void *data)
376 unsigned *num = data;
377 dom_info *bi = get_dom_info(bl);
379 bi->tree_pre_num = (*num)++;
382 static void assign_tree_dom_pre_order_max(ir_node *bl, void *data)
384 dom_info *bi = get_dom_info(bl);
387 unsigned children = 0;
389 for(p = bi->first; p; p = get_dom_info(p)->next) {
390 unsigned max_p = get_dom_info(p)->max_subtree_pre_num;
391 max = max > max_p ? max : max_p;
395 bi->max_subtree_pre_num = children > 0 ? max : bi->tree_pre_num;
396 assert(bi->max_subtree_pre_num >= bi->tree_pre_num);
399 static void assign_tree_postdom_pre_order(ir_node *bl, void *data)
401 unsigned *num = data;
402 dom_info *bi = get_pdom_info(bl);
404 bi->tree_pre_num = (*num)++;
407 static void assign_tree_postdom_pre_order_max(ir_node *bl, void *data)
409 dom_info *bi = get_pdom_info(bl);
412 unsigned children = 0;
414 for(p = bi->first; p; p = get_pdom_info(p)->next) {
415 unsigned max_p = get_pdom_info(p)->max_subtree_pre_num;
416 max = max > max_p ? max : max_p;
420 bi->max_subtree_pre_num = children > 0 ? max : bi->tree_pre_num;
421 assert(bi->max_subtree_pre_num >= bi->tree_pre_num);
424 /*--------------------------------------------------------------------*/
425 /* Building and Removing the dominator data structure */
426 /*--------------------------------------------------------------------*/
429 * count the number of blocks and clears the post dominance info
431 static void count_and_init_blocks_pdom(ir_node *bl, void *env) {
432 int *n_blocks = (int *) env;
435 memset(get_pdom_info(bl), 0, sizeof(dom_info));
436 set_Block_ipostdom(bl, NULL);
437 set_Block_postdom_pre_num(bl, -1);
438 set_Block_postdom_depth(bl, -1);
441 /** temporary type used while constructing the dominator / post dominator tree. */
442 typedef struct tmp_dom_info {
443 ir_node *block; /**< backlink */
445 struct tmp_dom_info *semi; /**< semidominator */
446 struct tmp_dom_info *parent;
447 struct tmp_dom_info *label; /**< used for LINK and EVAL */
448 struct tmp_dom_info *ancestor;/**< used for LINK and EVAL */
449 struct tmp_dom_info *dom; /**< After step 3, if the semidominator of w is
450 its immediate dominator, then w->dom is the
451 immediate dominator of w. Otherwise w->dom
452 is a vertex v whose number is smaller than
453 w and whose immediate dominator is also w's
454 immediate dominator. After step 4, w->dom
455 is the immediate dominator of w. */
456 struct tmp_dom_info *bucket; /**< set of vertices with same semidominator */
459 /** Struct to pass info through walker. */
467 * Walks Blocks along the out data structure. If recursion started with
468 * Start block misses control dead blocks.
470 static void init_tmp_dom_info(ir_node *bl, tmp_dom_info *parent,
471 tmp_dom_info *tdi_list, int *used, int n_blocks) {
475 assert(is_Block(bl));
476 if (get_irg_block_visited(current_ir_graph) == get_Block_block_visited(bl))
478 mark_Block_block_visited(bl);
479 set_Block_dom_pre_num(bl, *used);
481 assert(*used < n_blocks);
482 tdi = &tdi_list[*used];
487 tdi->ancestor = NULL;
489 tdi->parent = parent;
493 for (i = get_Block_n_cfg_outs_ka(bl) - 1; i >= 0; --i) {
494 ir_node *pred = get_Block_cfg_out_ka(bl, i);
495 assert(is_Block(pred));
496 init_tmp_dom_info(pred, tdi, tdi_list, used, n_blocks);
501 * Walks Blocks along the control flow. If recursion started with
502 * End block misses blocks in endless loops.
504 static void init_tmp_pdom_info(ir_node *bl, tmp_dom_info *parent,
505 tmp_dom_info *tdi_list, int* used, int n_blocks) {
509 assert(is_Block(bl));
510 if (get_irg_block_visited(current_ir_graph) == get_Block_block_visited(bl))
512 mark_Block_block_visited(bl);
513 set_Block_postdom_pre_num(bl, *used);
515 assert(*used < n_blocks);
516 tdi = &tdi_list[*used];
521 tdi->ancestor = NULL;
523 tdi->parent = parent;
527 for (i = get_Block_n_cfgpreds(bl) - 1; i >= 0; --i) {
528 ir_node *pred = get_Block_cfgpred_block(bl, i);
531 assert(is_Block(pred));
532 init_tmp_pdom_info(pred, tdi, tdi_list, used, n_blocks);
535 /* Handle keep-alives. Note that the preprocessing
536 in init_construction() had already killed all
537 phantom keep-alive edges. All remaining block keep-alives
538 are really edges to endless loops.
540 if (bl == get_irg_end_block(current_ir_graph)) {
541 ir_node *end = get_irg_end(current_ir_graph);
543 for (i = get_irn_arity(end) - 1; i >= 0; --i) {
544 ir_node *pred = get_irn_n(end, i);
547 init_tmp_pdom_info(pred, tdi, tdi_list, used, n_blocks);
552 static void dom_compress(tmp_dom_info *v)
554 assert (v->ancestor);
555 if (v->ancestor->ancestor) {
556 dom_compress (v->ancestor);
557 if (v->ancestor->label->semi < v->label->semi) {
558 v->label = v->ancestor->label;
560 v->ancestor = v->ancestor->ancestor;
565 * if V is a root, return v, else return the vertex u, not being the
566 * root, with minimum u->semi on the path from v to its root.
568 INLINE static tmp_dom_info *dom_eval (tmp_dom_info *v)
570 if (!v->ancestor) return v;
575 /** make V W's ancestor */
576 INLINE static void dom_link(tmp_dom_info *v, tmp_dom_info *w)
582 * Walker: count the number of blocks and clears the dominance info
584 static void count_and_init_blocks_dom(ir_node *bl, void *env) {
585 int *n_blocks = (int *) env;
588 memset(get_dom_info(bl), 0, sizeof(dom_info));
589 set_Block_idom(bl, NULL);
590 set_Block_dom_pre_num(bl, -1);
591 set_Block_dom_depth(bl, -1);
595 * Initialize the dominance/postdominance construction:
597 * - count the number of blocks
598 * - clear the dominance info
599 * - remove Block-keepalives of live blocks to reduce
600 * the number of "phantom" block edges
602 * @param irg the graph
603 * @param pre a walker function that will be called for every block in the graph
605 static int init_construction(ir_graph *irg, irg_walk_func *pre) {
606 ir_graph *rem = current_ir_graph;
611 current_ir_graph = irg;
613 /* this visits only the reachable blocks */
614 irg_block_walk(get_irg_end_block(irg), pre, NULL, &n_blocks);
616 /* now visit the unreachable (from End) Blocks and remove unnecessary keep-alives */
617 end = get_irg_end(irg);
618 arity = get_End_n_keepalives(end);
619 if (arity) { /* we have keep-alives */
623 NEW_ARR_A(ir_node *, in, arity);
624 for (i = j = 0; i < arity; i++) {
625 ir_node *pred = get_End_keepalive(end, i);
627 if (get_irn_op(pred) == op_Block) {
628 if (Block_not_block_visited(pred)) {
629 /* we found a endless loop */
630 dec_irg_block_visited(irg);
631 irg_block_walk(pred, pre, NULL, &n_blocks);
639 /* we kill some Block keep-alives */
640 set_End_keepalives(end, j, in);
641 set_irg_outs_inconsistent(irg);
645 current_ir_graph = rem;
650 /* Computes the dominator trees. Sets a flag in irg to "dom_consistent".
651 If the control flow of the graph is changed this flag must be set to
652 "dom_inconsistent". */
653 void compute_doms(ir_graph *irg) {
654 ir_graph *rem = current_ir_graph;
655 int n_blocks, used, i, j;
656 tmp_dom_info *tdi_list; /* Ein Golf? */
658 current_ir_graph = irg;
660 /* Update graph state */
661 assert(get_irg_phase_state(irg) != phase_building);
662 irg->dom_state = dom_consistent;
664 /* Count the number of blocks in the graph. */
665 n_blocks = init_construction(irg, count_and_init_blocks_dom);
667 /* Memory for temporary information. */
668 tdi_list = xcalloc(n_blocks, sizeof(tdi_list[0]));
670 /* We need the out data structure. */
671 assure_irg_outs(irg);
673 /* this with a standard walker as passing the parent to the sons isn't
676 inc_irg_block_visited(irg);
677 init_tmp_dom_info(get_irg_start_block(irg), NULL, tdi_list, &used, n_blocks);
678 /* If not all blocks are reachable from Start by out edges this assertion
680 assert(used == n_blocks && "Precondition for dom construction violated"); */
681 assert(used <= n_blocks && "Precondition for dom construction violated");
685 for (i = n_blocks-1; i > 0; i--) { /* Don't iterate the root, it's done. */
687 tmp_dom_info *w = &tdi_list[i];
691 irn_arity = get_irn_arity(w->block);
692 for (j = 0; j < irn_arity; j++) {
693 ir_node *pred = get_Block_cfgpred_block(w->block, j);
696 if (is_Bad(pred) || (get_Block_dom_pre_num (pred) == -1))
697 continue; /* control-dead */
699 u = dom_eval (&tdi_list[get_Block_dom_pre_num(pred)]);
700 if (u->semi < w->semi) w->semi = u->semi;
703 /* handle keep-alives if we are at the end block */
704 if (w->block == get_irg_end_block(irg)) {
705 ir_node *end = get_irg_end(irg);
707 irn_arity = get_irn_arity(end);
708 for (j = 0; j < irn_arity; j++) {
709 ir_node *pred = get_irn_n(end, j);
712 if (is_no_Block(pred) || get_Block_dom_pre_num(pred) == -1)
713 continue; /* control-dead */
715 u = dom_eval (&tdi_list[get_Block_dom_pre_num(pred)]);
716 if (u->semi < w->semi) w->semi = u->semi;
720 /* Add w to w->semi's bucket. w is in exactly one bucket, so
721 buckets can been implemented as linked lists. */
722 w->bucket = w->semi->bucket;
725 dom_link (w->parent, w);
728 while (w->parent->bucket) {
730 v = w->parent->bucket;
731 /* remove v from w->parent->bucket */
732 w->parent->bucket = v->bucket;
736 if (u->semi < v->semi)
743 tdi_list[0].dom = NULL;
744 set_Block_idom(tdi_list[0].block, NULL);
745 set_Block_dom_depth(tdi_list[0].block, 1);
746 for (i = 1; i < n_blocks; i++) {
747 tmp_dom_info *w = &tdi_list[i];
751 continue; /* control dead */
753 if (w->dom != w->semi) w->dom = w->dom->dom;
754 set_Block_idom(w->block, w->dom->block);
756 /* blocks dominated by dead one's are still dead */
757 depth = get_Block_dom_depth(w->dom->block);
760 set_Block_dom_depth(w->block, depth);
766 /* Do a walk over the tree and assign the tree pre orders. */
768 unsigned tree_pre_order = 0;
769 dom_tree_walk_irg(irg, assign_tree_dom_pre_order,
770 assign_tree_dom_pre_order_max, &tree_pre_order);
772 current_ir_graph = rem;
775 void assure_doms(ir_graph *irg) {
776 if (get_irg_dom_state(irg) != dom_consistent)
780 void free_dom(ir_graph *irg) {
781 /* Update graph state */
782 assert(get_irg_phase_state(current_ir_graph) != phase_building);
783 current_ir_graph->dom_state = dom_none;
785 /* With the implementation right now there is nothing to free,
786 but better call it anyways... */
789 /* Computes the post dominator trees. Sets a flag in irg to "dom_consistent".
790 If the control flow of the graph is changed this flag must be set to
791 "dom_inconsistent". */
792 void compute_postdoms(ir_graph *irg) {
793 ir_graph *rem = current_ir_graph;
794 int n_blocks, used, i, j;
795 tmp_dom_info *tdi_list;
797 current_ir_graph = irg;
799 /* Update graph state */
800 assert(get_irg_phase_state(irg) != phase_building);
801 irg->pdom_state = dom_consistent;
803 /* Count the number of blocks in the graph. */
804 n_blocks = init_construction(irg, count_and_init_blocks_pdom);
806 /* Memory for temporary information. */
807 tdi_list = xcalloc(n_blocks, sizeof(tdi_list[0]));
809 /* We need the out data structure. */
810 assure_irg_outs(irg);
812 /* this with a standard walker as passing the parent to the sons isn't
815 inc_irg_block_visited(irg);
816 init_tmp_pdom_info(get_irg_end_block(irg), NULL, tdi_list, &used, n_blocks);
817 /* If not all blocks are reachable from End by cfg edges this assertion
819 assert(used == n_blocks && "Precondition for dom construction violated"); */
823 for (i = n_blocks-1; i > 0; i--) { /* Don't iterate the root, it's done. */
825 tmp_dom_info *w = &tdi_list[i];
829 irn_arity = get_Block_n_cfg_outs_ka(w->block);
830 for (j = 0; j < irn_arity; j++) {
831 ir_node *succ = get_Block_cfg_out_ka(w->block, j);
834 if (get_Block_postdom_pre_num (succ) == -1)
835 continue; /* endless-loop */
837 u = dom_eval (&tdi_list[get_Block_postdom_pre_num(succ)]);
838 if (u->semi < w->semi) w->semi = u->semi;
840 /* Add w to w->semi's bucket. w is in exactly one bucket, so
841 buckets can be implemented as linked lists. */
842 w->bucket = w->semi->bucket;
845 dom_link (w->parent, w);
848 while (w->parent->bucket) {
850 v = w->parent->bucket;
851 /* remove v from w->parent->bucket */
852 w->parent->bucket = v->bucket;
856 if (u->semi < v->semi)
863 tdi_list[0].dom = NULL;
864 set_Block_ipostdom(tdi_list[0].block, NULL);
865 set_Block_postdom_depth(tdi_list[0].block, 1);
866 for (i = 1; i < n_blocks; i++) {
867 tmp_dom_info *w = &tdi_list[i];
869 if (w->dom != w->semi) w->dom = w->dom->dom;
870 set_Block_ipostdom(w->block, w->dom->block);
871 set_Block_postdom_depth(w->block, get_Block_postdom_depth(w->dom->block) + 1);
877 /* Do a walk over the tree and assign the tree pre orders. */
879 unsigned tree_pre_order = 0;
880 postdom_tree_walk_irg(irg, assign_tree_postdom_pre_order,
881 assign_tree_postdom_pre_order_max, &tree_pre_order);
883 current_ir_graph = rem;
886 void assure_postdoms(ir_graph *irg) {
887 if (get_irg_postdom_state(irg) != dom_consistent)
888 compute_postdoms(irg);
891 void free_postdom(ir_graph *irg) {
892 /* Update graph state */
893 assert(get_irg_phase_state(current_ir_graph) != phase_building);
894 current_ir_graph->pdom_state = dom_none;
896 /* With the implementation right now there is nothing to free,
897 but better call it anyways... */