2012-09-04 Janus Weil <janus@gcc.gnu.org>
[official-gcc.git] / gcc / dominance.c
blob10a58cd8a2a47081b3146c9c61fc35f5b28c355f
1 /* Calculate (post)dominators in slightly super-linear time.
2 Copyright (C) 2000, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010
3 Free Software Foundation, Inc.
4 Contributed by Michael Matz (matz@ifh.de).
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it
9 under the terms of the GNU General Public License as published by
10 the Free Software Foundation; either version 3, or (at your option)
11 any later version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT
14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
16 License for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* This file implements the well known algorithm from Lengauer and Tarjan
23 to compute the dominators in a control flow graph. A basic block D is said
24 to dominate another block X, when all paths from the entry node of the CFG
25 to X go also over D. The dominance relation is a transitive reflexive
26 relation and its minimal transitive reduction is a tree, called the
27 dominator tree. So for each block X besides the entry block exists a
28 block I(X), called the immediate dominator of X, which is the parent of X
29 in the dominator tree.
31 The algorithm computes this dominator tree implicitly by computing for
32 each block its immediate dominator. We use tree balancing and path
33 compression, so it's the O(e*a(e,v)) variant, where a(e,v) is the very
34 slowly growing functional inverse of the Ackerman function. */
36 #include "config.h"
37 #include "system.h"
38 #include "coretypes.h"
39 #include "tm.h"
40 #include "rtl.h"
41 #include "hard-reg-set.h"
42 #include "obstack.h"
43 #include "basic-block.h"
44 #include "diagnostic-core.h"
45 #include "et-forest.h"
46 #include "timevar.h"
47 #include "vecprim.h"
48 #include "pointer-set.h"
49 #include "graphds.h"
50 #include "bitmap.h"
52 /* We name our nodes with integers, beginning with 1. Zero is reserved for
53 'undefined' or 'end of list'. The name of each node is given by the dfs
54 number of the corresponding basic block. Please note, that we include the
55 artificial ENTRY_BLOCK (or EXIT_BLOCK in the post-dom case) in our lists to
56 support multiple entry points. Its dfs number is of course 1. */
58 /* Type of Basic Block aka. TBB */
59 typedef unsigned int TBB;
61 /* We work in a poor-mans object oriented fashion, and carry an instance of
62 this structure through all our 'methods'. It holds various arrays
63 reflecting the (sub)structure of the flowgraph. Most of them are of type
64 TBB and are also indexed by TBB. */
66 struct dom_info
68 /* The parent of a node in the DFS tree. */
69 TBB *dfs_parent;
70 /* For a node x key[x] is roughly the node nearest to the root from which
71 exists a way to x only over nodes behind x. Such a node is also called
72 semidominator. */
73 TBB *key;
74 /* The value in path_min[x] is the node y on the path from x to the root of
75 the tree x is in with the smallest key[y]. */
76 TBB *path_min;
77 /* bucket[x] points to the first node of the set of nodes having x as key. */
78 TBB *bucket;
79 /* And next_bucket[x] points to the next node. */
80 TBB *next_bucket;
81 /* After the algorithm is done, dom[x] contains the immediate dominator
82 of x. */
83 TBB *dom;
85 /* The following few fields implement the structures needed for disjoint
86 sets. */
87 /* set_chain[x] is the next node on the path from x to the representative
88 of the set containing x. If set_chain[x]==0 then x is a root. */
89 TBB *set_chain;
90 /* set_size[x] is the number of elements in the set named by x. */
91 unsigned int *set_size;
92 /* set_child[x] is used for balancing the tree representing a set. It can
93 be understood as the next sibling of x. */
94 TBB *set_child;
96 /* If b is the number of a basic block (BB->index), dfs_order[b] is the
97 number of that node in DFS order counted from 1. This is an index
98 into most of the other arrays in this structure. */
99 TBB *dfs_order;
100 /* If x is the DFS-index of a node which corresponds with a basic block,
101 dfs_to_bb[x] is that basic block. Note, that in our structure there are
102 more nodes that basic blocks, so only dfs_to_bb[dfs_order[bb->index]]==bb
103 is true for every basic block bb, but not the opposite. */
104 basic_block *dfs_to_bb;
106 /* This is the next free DFS number when creating the DFS tree. */
107 unsigned int dfsnum;
108 /* The number of nodes in the DFS tree (==dfsnum-1). */
109 unsigned int nodes;
111 /* Blocks with bits set here have a fake edge to EXIT. These are used
112 to turn a DFS forest into a proper tree. */
113 bitmap fake_exit_edge;
116 static void init_dom_info (struct dom_info *, enum cdi_direction);
117 static void free_dom_info (struct dom_info *);
118 static void calc_dfs_tree_nonrec (struct dom_info *, basic_block, bool);
119 static void calc_dfs_tree (struct dom_info *, bool);
120 static void compress (struct dom_info *, TBB);
121 static TBB eval (struct dom_info *, TBB);
122 static void link_roots (struct dom_info *, TBB, TBB);
123 static void calc_idoms (struct dom_info *, bool);
124 void debug_dominance_info (enum cdi_direction);
125 void debug_dominance_tree (enum cdi_direction, basic_block);
127 /* Helper macro for allocating and initializing an array,
128 for aesthetic reasons. */
129 #define init_ar(var, type, num, content) \
130 do \
132 unsigned int i = 1; /* Catch content == i. */ \
133 if (! (content)) \
134 (var) = XCNEWVEC (type, num); \
135 else \
137 (var) = XNEWVEC (type, (num)); \
138 for (i = 0; i < num; i++) \
139 (var)[i] = (content); \
142 while (0)
144 /* Allocate all needed memory in a pessimistic fashion (so we round up).
145 This initializes the contents of DI, which already must be allocated. */
147 static void
148 init_dom_info (struct dom_info *di, enum cdi_direction dir)
150 /* We need memory for n_basic_blocks nodes. */
151 unsigned int num = n_basic_blocks;
152 init_ar (di->dfs_parent, TBB, num, 0);
153 init_ar (di->path_min, TBB, num, i);
154 init_ar (di->key, TBB, num, i);
155 init_ar (di->dom, TBB, num, 0);
157 init_ar (di->bucket, TBB, num, 0);
158 init_ar (di->next_bucket, TBB, num, 0);
160 init_ar (di->set_chain, TBB, num, 0);
161 init_ar (di->set_size, unsigned int, num, 1);
162 init_ar (di->set_child, TBB, num, 0);
164 init_ar (di->dfs_order, TBB, (unsigned int) last_basic_block + 1, 0);
165 init_ar (di->dfs_to_bb, basic_block, num, 0);
167 di->dfsnum = 1;
168 di->nodes = 0;
170 switch (dir)
172 case CDI_DOMINATORS:
173 di->fake_exit_edge = NULL;
174 break;
175 case CDI_POST_DOMINATORS:
176 di->fake_exit_edge = BITMAP_ALLOC (NULL);
177 break;
178 default:
179 gcc_unreachable ();
180 break;
184 #undef init_ar
186 /* Map dominance calculation type to array index used for various
187 dominance information arrays. This version is simple -- it will need
188 to be modified, obviously, if additional values are added to
189 cdi_direction. */
191 static unsigned int
192 dom_convert_dir_to_idx (enum cdi_direction dir)
194 gcc_checking_assert (dir == CDI_DOMINATORS || dir == CDI_POST_DOMINATORS);
195 return dir - 1;
198 /* Free all allocated memory in DI, but not DI itself. */
200 static void
201 free_dom_info (struct dom_info *di)
203 free (di->dfs_parent);
204 free (di->path_min);
205 free (di->key);
206 free (di->dom);
207 free (di->bucket);
208 free (di->next_bucket);
209 free (di->set_chain);
210 free (di->set_size);
211 free (di->set_child);
212 free (di->dfs_order);
213 free (di->dfs_to_bb);
214 BITMAP_FREE (di->fake_exit_edge);
217 /* The nonrecursive variant of creating a DFS tree. DI is our working
218 structure, BB the starting basic block for this tree and REVERSE
219 is true, if predecessors should be visited instead of successors of a
220 node. After this is done all nodes reachable from BB were visited, have
221 assigned their dfs number and are linked together to form a tree. */
223 static void
224 calc_dfs_tree_nonrec (struct dom_info *di, basic_block bb, bool reverse)
226 /* We call this _only_ if bb is not already visited. */
227 edge e;
228 TBB child_i, my_i = 0;
229 edge_iterator *stack;
230 edge_iterator ei, einext;
231 int sp;
232 /* Start block (ENTRY_BLOCK_PTR for forward problem, EXIT_BLOCK for backward
233 problem). */
234 basic_block en_block;
235 /* Ending block. */
236 basic_block ex_block;
238 stack = XNEWVEC (edge_iterator, n_basic_blocks + 1);
239 sp = 0;
241 /* Initialize our border blocks, and the first edge. */
242 if (reverse)
244 ei = ei_start (bb->preds);
245 en_block = EXIT_BLOCK_PTR;
246 ex_block = ENTRY_BLOCK_PTR;
248 else
250 ei = ei_start (bb->succs);
251 en_block = ENTRY_BLOCK_PTR;
252 ex_block = EXIT_BLOCK_PTR;
255 /* When the stack is empty we break out of this loop. */
256 while (1)
258 basic_block bn;
260 /* This loop traverses edges e in depth first manner, and fills the
261 stack. */
262 while (!ei_end_p (ei))
264 e = ei_edge (ei);
266 /* Deduce from E the current and the next block (BB and BN), and the
267 next edge. */
268 if (reverse)
270 bn = e->src;
272 /* If the next node BN is either already visited or a border
273 block the current edge is useless, and simply overwritten
274 with the next edge out of the current node. */
275 if (bn == ex_block || di->dfs_order[bn->index])
277 ei_next (&ei);
278 continue;
280 bb = e->dest;
281 einext = ei_start (bn->preds);
283 else
285 bn = e->dest;
286 if (bn == ex_block || di->dfs_order[bn->index])
288 ei_next (&ei);
289 continue;
291 bb = e->src;
292 einext = ei_start (bn->succs);
295 gcc_assert (bn != en_block);
297 /* Fill the DFS tree info calculatable _before_ recursing. */
298 if (bb != en_block)
299 my_i = di->dfs_order[bb->index];
300 else
301 my_i = di->dfs_order[last_basic_block];
302 child_i = di->dfs_order[bn->index] = di->dfsnum++;
303 di->dfs_to_bb[child_i] = bn;
304 di->dfs_parent[child_i] = my_i;
306 /* Save the current point in the CFG on the stack, and recurse. */
307 stack[sp++] = ei;
308 ei = einext;
311 if (!sp)
312 break;
313 ei = stack[--sp];
315 /* OK. The edge-list was exhausted, meaning normally we would
316 end the recursion. After returning from the recursive call,
317 there were (may be) other statements which were run after a
318 child node was completely considered by DFS. Here is the
319 point to do it in the non-recursive variant.
320 E.g. The block just completed is in e->dest for forward DFS,
321 the block not yet completed (the parent of the one above)
322 in e->src. This could be used e.g. for computing the number of
323 descendants or the tree depth. */
324 ei_next (&ei);
326 free (stack);
329 /* The main entry for calculating the DFS tree or forest. DI is our working
330 structure and REVERSE is true, if we are interested in the reverse flow
331 graph. In that case the result is not necessarily a tree but a forest,
332 because there may be nodes from which the EXIT_BLOCK is unreachable. */
334 static void
335 calc_dfs_tree (struct dom_info *di, bool reverse)
337 /* The first block is the ENTRY_BLOCK (or EXIT_BLOCK if REVERSE). */
338 basic_block begin = reverse ? EXIT_BLOCK_PTR : ENTRY_BLOCK_PTR;
339 di->dfs_order[last_basic_block] = di->dfsnum;
340 di->dfs_to_bb[di->dfsnum] = begin;
341 di->dfsnum++;
343 calc_dfs_tree_nonrec (di, begin, reverse);
345 if (reverse)
347 /* In the post-dom case we may have nodes without a path to EXIT_BLOCK.
348 They are reverse-unreachable. In the dom-case we disallow such
349 nodes, but in post-dom we have to deal with them.
351 There are two situations in which this occurs. First, noreturn
352 functions. Second, infinite loops. In the first case we need to
353 pretend that there is an edge to the exit block. In the second
354 case, we wind up with a forest. We need to process all noreturn
355 blocks before we know if we've got any infinite loops. */
357 basic_block b;
358 bool saw_unconnected = false;
360 FOR_EACH_BB_REVERSE (b)
362 if (EDGE_COUNT (b->succs) > 0)
364 if (di->dfs_order[b->index] == 0)
365 saw_unconnected = true;
366 continue;
368 bitmap_set_bit (di->fake_exit_edge, b->index);
369 di->dfs_order[b->index] = di->dfsnum;
370 di->dfs_to_bb[di->dfsnum] = b;
371 di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block];
372 di->dfsnum++;
373 calc_dfs_tree_nonrec (di, b, reverse);
376 if (saw_unconnected)
378 FOR_EACH_BB_REVERSE (b)
380 if (di->dfs_order[b->index])
381 continue;
382 bitmap_set_bit (di->fake_exit_edge, b->index);
383 di->dfs_order[b->index] = di->dfsnum;
384 di->dfs_to_bb[di->dfsnum] = b;
385 di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block];
386 di->dfsnum++;
387 calc_dfs_tree_nonrec (di, b, reverse);
392 di->nodes = di->dfsnum - 1;
394 /* This aborts e.g. when there is _no_ path from ENTRY to EXIT at all. */
395 gcc_assert (di->nodes == (unsigned int) n_basic_blocks - 1);
398 /* Compress the path from V to the root of its set and update path_min at the
399 same time. After compress(di, V) set_chain[V] is the root of the set V is
400 in and path_min[V] is the node with the smallest key[] value on the path
401 from V to that root. */
403 static void
404 compress (struct dom_info *di, TBB v)
406 /* Btw. It's not worth to unrecurse compress() as the depth is usually not
407 greater than 5 even for huge graphs (I've not seen call depth > 4).
408 Also performance wise compress() ranges _far_ behind eval(). */
409 TBB parent = di->set_chain[v];
410 if (di->set_chain[parent])
412 compress (di, parent);
413 if (di->key[di->path_min[parent]] < di->key[di->path_min[v]])
414 di->path_min[v] = di->path_min[parent];
415 di->set_chain[v] = di->set_chain[parent];
419 /* Compress the path from V to the set root of V if needed (when the root has
420 changed since the last call). Returns the node with the smallest key[]
421 value on the path from V to the root. */
423 static inline TBB
424 eval (struct dom_info *di, TBB v)
426 /* The representative of the set V is in, also called root (as the set
427 representation is a tree). */
428 TBB rep = di->set_chain[v];
430 /* V itself is the root. */
431 if (!rep)
432 return di->path_min[v];
434 /* Compress only if necessary. */
435 if (di->set_chain[rep])
437 compress (di, v);
438 rep = di->set_chain[v];
441 if (di->key[di->path_min[rep]] >= di->key[di->path_min[v]])
442 return di->path_min[v];
443 else
444 return di->path_min[rep];
447 /* This essentially merges the two sets of V and W, giving a single set with
448 the new root V. The internal representation of these disjoint sets is a
449 balanced tree. Currently link(V,W) is only used with V being the parent
450 of W. */
452 static void
453 link_roots (struct dom_info *di, TBB v, TBB w)
455 TBB s = w;
457 /* Rebalance the tree. */
458 while (di->key[di->path_min[w]] < di->key[di->path_min[di->set_child[s]]])
460 if (di->set_size[s] + di->set_size[di->set_child[di->set_child[s]]]
461 >= 2 * di->set_size[di->set_child[s]])
463 di->set_chain[di->set_child[s]] = s;
464 di->set_child[s] = di->set_child[di->set_child[s]];
466 else
468 di->set_size[di->set_child[s]] = di->set_size[s];
469 s = di->set_chain[s] = di->set_child[s];
473 di->path_min[s] = di->path_min[w];
474 di->set_size[v] += di->set_size[w];
475 if (di->set_size[v] < 2 * di->set_size[w])
477 TBB tmp = s;
478 s = di->set_child[v];
479 di->set_child[v] = tmp;
482 /* Merge all subtrees. */
483 while (s)
485 di->set_chain[s] = v;
486 s = di->set_child[s];
490 /* This calculates the immediate dominators (or post-dominators if REVERSE is
491 true). DI is our working structure and should hold the DFS forest.
492 On return the immediate dominator to node V is in di->dom[V]. */
494 static void
495 calc_idoms (struct dom_info *di, bool reverse)
497 TBB v, w, k, par;
498 basic_block en_block;
499 edge_iterator ei, einext;
501 if (reverse)
502 en_block = EXIT_BLOCK_PTR;
503 else
504 en_block = ENTRY_BLOCK_PTR;
506 /* Go backwards in DFS order, to first look at the leafs. */
507 v = di->nodes;
508 while (v > 1)
510 basic_block bb = di->dfs_to_bb[v];
511 edge e;
513 par = di->dfs_parent[v];
514 k = v;
516 ei = (reverse) ? ei_start (bb->succs) : ei_start (bb->preds);
518 if (reverse)
520 /* If this block has a fake edge to exit, process that first. */
521 if (bitmap_bit_p (di->fake_exit_edge, bb->index))
523 einext = ei;
524 einext.index = 0;
525 goto do_fake_exit_edge;
529 /* Search all direct predecessors for the smallest node with a path
530 to them. That way we have the smallest node with also a path to
531 us only over nodes behind us. In effect we search for our
532 semidominator. */
533 while (!ei_end_p (ei))
535 TBB k1;
536 basic_block b;
538 e = ei_edge (ei);
539 b = (reverse) ? e->dest : e->src;
540 einext = ei;
541 ei_next (&einext);
543 if (b == en_block)
545 do_fake_exit_edge:
546 k1 = di->dfs_order[last_basic_block];
548 else
549 k1 = di->dfs_order[b->index];
551 /* Call eval() only if really needed. If k1 is above V in DFS tree,
552 then we know, that eval(k1) == k1 and key[k1] == k1. */
553 if (k1 > v)
554 k1 = di->key[eval (di, k1)];
555 if (k1 < k)
556 k = k1;
558 ei = einext;
561 di->key[v] = k;
562 link_roots (di, par, v);
563 di->next_bucket[v] = di->bucket[k];
564 di->bucket[k] = v;
566 /* Transform semidominators into dominators. */
567 for (w = di->bucket[par]; w; w = di->next_bucket[w])
569 k = eval (di, w);
570 if (di->key[k] < di->key[w])
571 di->dom[w] = k;
572 else
573 di->dom[w] = par;
575 /* We don't need to cleanup next_bucket[]. */
576 di->bucket[par] = 0;
577 v--;
580 /* Explicitly define the dominators. */
581 di->dom[1] = 0;
582 for (v = 2; v <= di->nodes; v++)
583 if (di->dom[v] != di->key[v])
584 di->dom[v] = di->dom[di->dom[v]];
587 /* Assign dfs numbers starting from NUM to NODE and its sons. */
589 static void
590 assign_dfs_numbers (struct et_node *node, int *num)
592 struct et_node *son;
594 node->dfs_num_in = (*num)++;
596 if (node->son)
598 assign_dfs_numbers (node->son, num);
599 for (son = node->son->right; son != node->son; son = son->right)
600 assign_dfs_numbers (son, num);
603 node->dfs_num_out = (*num)++;
606 /* Compute the data necessary for fast resolving of dominator queries in a
607 static dominator tree. */
609 static void
610 compute_dom_fast_query (enum cdi_direction dir)
612 int num = 0;
613 basic_block bb;
614 unsigned int dir_index = dom_convert_dir_to_idx (dir);
616 gcc_checking_assert (dom_info_available_p (dir));
618 if (dom_computed[dir_index] == DOM_OK)
619 return;
621 FOR_ALL_BB (bb)
623 if (!bb->dom[dir_index]->father)
624 assign_dfs_numbers (bb->dom[dir_index], &num);
627 dom_computed[dir_index] = DOM_OK;
630 /* The main entry point into this module. DIR is set depending on whether
631 we want to compute dominators or postdominators. */
633 void
634 calculate_dominance_info (enum cdi_direction dir)
636 struct dom_info di;
637 basic_block b;
638 unsigned int dir_index = dom_convert_dir_to_idx (dir);
639 bool reverse = (dir == CDI_POST_DOMINATORS) ? true : false;
641 if (dom_computed[dir_index] == DOM_OK)
642 return;
644 timevar_push (TV_DOMINANCE);
645 if (!dom_info_available_p (dir))
647 gcc_assert (!n_bbs_in_dom_tree[dir_index]);
649 FOR_ALL_BB (b)
651 b->dom[dir_index] = et_new_tree (b);
653 n_bbs_in_dom_tree[dir_index] = n_basic_blocks;
655 init_dom_info (&di, dir);
656 calc_dfs_tree (&di, reverse);
657 calc_idoms (&di, reverse);
659 FOR_EACH_BB (b)
661 TBB d = di.dom[di.dfs_order[b->index]];
663 if (di.dfs_to_bb[d])
664 et_set_father (b->dom[dir_index], di.dfs_to_bb[d]->dom[dir_index]);
667 free_dom_info (&di);
668 dom_computed[dir_index] = DOM_NO_FAST_QUERY;
671 compute_dom_fast_query (dir);
673 timevar_pop (TV_DOMINANCE);
676 /* Free dominance information for direction DIR. */
677 void
678 free_dominance_info (enum cdi_direction dir)
680 basic_block bb;
681 unsigned int dir_index = dom_convert_dir_to_idx (dir);
683 if (!dom_info_available_p (dir))
684 return;
686 FOR_ALL_BB (bb)
688 et_free_tree_force (bb->dom[dir_index]);
689 bb->dom[dir_index] = NULL;
691 et_free_pools ();
693 n_bbs_in_dom_tree[dir_index] = 0;
695 dom_computed[dir_index] = DOM_NONE;
698 /* Return the immediate dominator of basic block BB. */
699 basic_block
700 get_immediate_dominator (enum cdi_direction dir, basic_block bb)
702 unsigned int dir_index = dom_convert_dir_to_idx (dir);
703 struct et_node *node = bb->dom[dir_index];
705 gcc_checking_assert (dom_computed[dir_index]);
707 if (!node->father)
708 return NULL;
710 return (basic_block) node->father->data;
713 /* Set the immediate dominator of the block possibly removing
714 existing edge. NULL can be used to remove any edge. */
715 void
716 set_immediate_dominator (enum cdi_direction dir, basic_block bb,
717 basic_block dominated_by)
719 unsigned int dir_index = dom_convert_dir_to_idx (dir);
720 struct et_node *node = bb->dom[dir_index];
722 gcc_checking_assert (dom_computed[dir_index]);
724 if (node->father)
726 if (node->father->data == dominated_by)
727 return;
728 et_split (node);
731 if (dominated_by)
732 et_set_father (node, dominated_by->dom[dir_index]);
734 if (dom_computed[dir_index] == DOM_OK)
735 dom_computed[dir_index] = DOM_NO_FAST_QUERY;
738 /* Returns the list of basic blocks immediately dominated by BB, in the
739 direction DIR. */
740 VEC (basic_block, heap) *
741 get_dominated_by (enum cdi_direction dir, basic_block bb)
743 unsigned int dir_index = dom_convert_dir_to_idx (dir);
744 struct et_node *node = bb->dom[dir_index], *son = node->son, *ason;
745 VEC (basic_block, heap) *bbs = NULL;
747 gcc_checking_assert (dom_computed[dir_index]);
749 if (!son)
750 return NULL;
752 VEC_safe_push (basic_block, heap, bbs, (basic_block) son->data);
753 for (ason = son->right; ason != son; ason = ason->right)
754 VEC_safe_push (basic_block, heap, bbs, (basic_block) ason->data);
756 return bbs;
759 /* Returns the list of basic blocks that are immediately dominated (in
760 direction DIR) by some block between N_REGION ones stored in REGION,
761 except for blocks in the REGION itself. */
763 VEC (basic_block, heap) *
764 get_dominated_by_region (enum cdi_direction dir, basic_block *region,
765 unsigned n_region)
767 unsigned i;
768 basic_block dom;
769 VEC (basic_block, heap) *doms = NULL;
771 for (i = 0; i < n_region; i++)
772 region[i]->flags |= BB_DUPLICATED;
773 for (i = 0; i < n_region; i++)
774 for (dom = first_dom_son (dir, region[i]);
775 dom;
776 dom = next_dom_son (dir, dom))
777 if (!(dom->flags & BB_DUPLICATED))
778 VEC_safe_push (basic_block, heap, doms, dom);
779 for (i = 0; i < n_region; i++)
780 region[i]->flags &= ~BB_DUPLICATED;
782 return doms;
785 /* Returns the list of basic blocks including BB dominated by BB, in the
786 direction DIR up to DEPTH in the dominator tree. The DEPTH of zero will
787 produce a vector containing all dominated blocks. The vector will be sorted
788 in preorder. */
790 VEC (basic_block, heap) *
791 get_dominated_to_depth (enum cdi_direction dir, basic_block bb, int depth)
793 VEC(basic_block, heap) *bbs = NULL;
794 unsigned i;
795 unsigned next_level_start;
797 i = 0;
798 VEC_safe_push (basic_block, heap, bbs, bb);
799 next_level_start = 1; /* = VEC_length (basic_block, bbs); */
803 basic_block son;
805 bb = VEC_index (basic_block, bbs, i++);
806 for (son = first_dom_son (dir, bb);
807 son;
808 son = next_dom_son (dir, son))
809 VEC_safe_push (basic_block, heap, bbs, son);
811 if (i == next_level_start && --depth)
812 next_level_start = VEC_length (basic_block, bbs);
814 while (i < next_level_start);
816 return bbs;
819 /* Returns the list of basic blocks including BB dominated by BB, in the
820 direction DIR. The vector will be sorted in preorder. */
822 VEC (basic_block, heap) *
823 get_all_dominated_blocks (enum cdi_direction dir, basic_block bb)
825 return get_dominated_to_depth (dir, bb, 0);
828 /* Redirect all edges pointing to BB to TO. */
829 void
830 redirect_immediate_dominators (enum cdi_direction dir, basic_block bb,
831 basic_block to)
833 unsigned int dir_index = dom_convert_dir_to_idx (dir);
834 struct et_node *bb_node, *to_node, *son;
836 bb_node = bb->dom[dir_index];
837 to_node = to->dom[dir_index];
839 gcc_checking_assert (dom_computed[dir_index]);
841 if (!bb_node->son)
842 return;
844 while (bb_node->son)
846 son = bb_node->son;
848 et_split (son);
849 et_set_father (son, to_node);
852 if (dom_computed[dir_index] == DOM_OK)
853 dom_computed[dir_index] = DOM_NO_FAST_QUERY;
856 /* Find first basic block in the tree dominating both BB1 and BB2. */
857 basic_block
858 nearest_common_dominator (enum cdi_direction dir, basic_block bb1, basic_block bb2)
860 unsigned int dir_index = dom_convert_dir_to_idx (dir);
862 gcc_checking_assert (dom_computed[dir_index]);
864 if (!bb1)
865 return bb2;
866 if (!bb2)
867 return bb1;
869 return (basic_block) et_nca (bb1->dom[dir_index], bb2->dom[dir_index])->data;
873 /* Find the nearest common dominator for the basic blocks in BLOCKS,
874 using dominance direction DIR. */
876 basic_block
877 nearest_common_dominator_for_set (enum cdi_direction dir, bitmap blocks)
879 unsigned i, first;
880 bitmap_iterator bi;
881 basic_block dom;
883 first = bitmap_first_set_bit (blocks);
884 dom = BASIC_BLOCK (first);
885 EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi)
886 if (dom != BASIC_BLOCK (i))
887 dom = nearest_common_dominator (dir, dom, BASIC_BLOCK (i));
889 return dom;
892 /* Given a dominator tree, we can determine whether one thing
893 dominates another in constant time by using two DFS numbers:
895 1. The number for when we visit a node on the way down the tree
896 2. The number for when we visit a node on the way back up the tree
898 You can view these as bounds for the range of dfs numbers the
899 nodes in the subtree of the dominator tree rooted at that node
900 will contain.
902 The dominator tree is always a simple acyclic tree, so there are
903 only three possible relations two nodes in the dominator tree have
904 to each other:
906 1. Node A is above Node B (and thus, Node A dominates node B)
915 In the above case, DFS_Number_In of A will be <= DFS_Number_In of
916 B, and DFS_Number_Out of A will be >= DFS_Number_Out of B. This is
917 because we must hit A in the dominator tree *before* B on the walk
918 down, and we will hit A *after* B on the walk back up
920 2. Node A is below node B (and thus, node B dominates node A)
929 In the above case, DFS_Number_In of A will be >= DFS_Number_In of
930 B, and DFS_Number_Out of A will be <= DFS_Number_Out of B.
932 This is because we must hit A in the dominator tree *after* B on
933 the walk down, and we will hit A *before* B on the walk back up
935 3. Node A and B are siblings (and thus, neither dominates the other)
943 In the above case, DFS_Number_In of A will *always* be <=
944 DFS_Number_In of B, and DFS_Number_Out of A will *always* be <=
945 DFS_Number_Out of B. This is because we will always finish the dfs
946 walk of one of the subtrees before the other, and thus, the dfs
947 numbers for one subtree can't intersect with the range of dfs
948 numbers for the other subtree. If you swap A and B's position in
949 the dominator tree, the comparison changes direction, but the point
950 is that both comparisons will always go the same way if there is no
951 dominance relationship.
953 Thus, it is sufficient to write
955 A_Dominates_B (node A, node B)
957 return DFS_Number_In(A) <= DFS_Number_In(B)
958 && DFS_Number_Out (A) >= DFS_Number_Out(B);
961 A_Dominated_by_B (node A, node B)
963 return DFS_Number_In(A) >= DFS_Number_In(A)
964 && DFS_Number_Out (A) <= DFS_Number_Out(B);
965 } */
967 /* Return TRUE in case BB1 is dominated by BB2. */
968 bool
969 dominated_by_p (enum cdi_direction dir, const_basic_block bb1, const_basic_block bb2)
971 unsigned int dir_index = dom_convert_dir_to_idx (dir);
972 struct et_node *n1 = bb1->dom[dir_index], *n2 = bb2->dom[dir_index];
974 gcc_checking_assert (dom_computed[dir_index]);
976 if (dom_computed[dir_index] == DOM_OK)
977 return (n1->dfs_num_in >= n2->dfs_num_in
978 && n1->dfs_num_out <= n2->dfs_num_out);
980 return et_below (n1, n2);
983 /* Returns the entry dfs number for basic block BB, in the direction DIR. */
985 unsigned
986 bb_dom_dfs_in (enum cdi_direction dir, basic_block bb)
988 unsigned int dir_index = dom_convert_dir_to_idx (dir);
989 struct et_node *n = bb->dom[dir_index];
991 gcc_checking_assert (dom_computed[dir_index] == DOM_OK);
992 return n->dfs_num_in;
995 /* Returns the exit dfs number for basic block BB, in the direction DIR. */
997 unsigned
998 bb_dom_dfs_out (enum cdi_direction dir, basic_block bb)
1000 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1001 struct et_node *n = bb->dom[dir_index];
1003 gcc_checking_assert (dom_computed[dir_index] == DOM_OK);
1004 return n->dfs_num_out;
1007 /* Verify invariants of dominator structure. */
1008 DEBUG_FUNCTION void
1009 verify_dominators (enum cdi_direction dir)
1011 int err = 0;
1012 basic_block bb, imm_bb, imm_bb_correct;
1013 struct dom_info di;
1014 bool reverse = (dir == CDI_POST_DOMINATORS) ? true : false;
1016 gcc_assert (dom_info_available_p (dir));
1018 init_dom_info (&di, dir);
1019 calc_dfs_tree (&di, reverse);
1020 calc_idoms (&di, reverse);
1022 FOR_EACH_BB (bb)
1024 imm_bb = get_immediate_dominator (dir, bb);
1025 if (!imm_bb)
1027 error ("dominator of %d status unknown", bb->index);
1028 err = 1;
1031 imm_bb_correct = di.dfs_to_bb[di.dom[di.dfs_order[bb->index]]];
1032 if (imm_bb != imm_bb_correct)
1034 error ("dominator of %d should be %d, not %d",
1035 bb->index, imm_bb_correct->index, imm_bb->index);
1036 err = 1;
1040 free_dom_info (&di);
1041 gcc_assert (!err);
1044 /* Determine immediate dominator (or postdominator, according to DIR) of BB,
1045 assuming that dominators of other blocks are correct. We also use it to
1046 recompute the dominators in a restricted area, by iterating it until it
1047 reaches a fixed point. */
1049 basic_block
1050 recompute_dominator (enum cdi_direction dir, basic_block bb)
1052 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1053 basic_block dom_bb = NULL;
1054 edge e;
1055 edge_iterator ei;
1057 gcc_checking_assert (dom_computed[dir_index]);
1059 if (dir == CDI_DOMINATORS)
1061 FOR_EACH_EDGE (e, ei, bb->preds)
1063 if (!dominated_by_p (dir, e->src, bb))
1064 dom_bb = nearest_common_dominator (dir, dom_bb, e->src);
1067 else
1069 FOR_EACH_EDGE (e, ei, bb->succs)
1071 if (!dominated_by_p (dir, e->dest, bb))
1072 dom_bb = nearest_common_dominator (dir, dom_bb, e->dest);
1076 return dom_bb;
1079 /* Use simple heuristics (see iterate_fix_dominators) to determine dominators
1080 of BBS. We assume that all the immediate dominators except for those of the
1081 blocks in BBS are correct. If CONSERVATIVE is true, we also assume that the
1082 currently recorded immediate dominators of blocks in BBS really dominate the
1083 blocks. The basic blocks for that we determine the dominator are removed
1084 from BBS. */
1086 static void
1087 prune_bbs_to_update_dominators (VEC (basic_block, heap) *bbs,
1088 bool conservative)
1090 unsigned i;
1091 bool single;
1092 basic_block bb, dom = NULL;
1093 edge_iterator ei;
1094 edge e;
1096 for (i = 0; VEC_iterate (basic_block, bbs, i, bb);)
1098 if (bb == ENTRY_BLOCK_PTR)
1099 goto succeed;
1101 if (single_pred_p (bb))
1103 set_immediate_dominator (CDI_DOMINATORS, bb, single_pred (bb));
1104 goto succeed;
1107 if (!conservative)
1108 goto fail;
1110 single = true;
1111 dom = NULL;
1112 FOR_EACH_EDGE (e, ei, bb->preds)
1114 if (dominated_by_p (CDI_DOMINATORS, e->src, bb))
1115 continue;
1117 if (!dom)
1118 dom = e->src;
1119 else
1121 single = false;
1122 dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src);
1126 gcc_assert (dom != NULL);
1127 if (single
1128 || find_edge (dom, bb))
1130 set_immediate_dominator (CDI_DOMINATORS, bb, dom);
1131 goto succeed;
1134 fail:
1135 i++;
1136 continue;
1138 succeed:
1139 VEC_unordered_remove (basic_block, bbs, i);
1143 /* Returns root of the dominance tree in the direction DIR that contains
1144 BB. */
1146 static basic_block
1147 root_of_dom_tree (enum cdi_direction dir, basic_block bb)
1149 return (basic_block) et_root (bb->dom[dom_convert_dir_to_idx (dir)])->data;
1152 /* See the comment in iterate_fix_dominators. Finds the immediate dominators
1153 for the sons of Y, found using the SON and BROTHER arrays representing
1154 the dominance tree of graph G. BBS maps the vertices of G to the basic
1155 blocks. */
1157 static void
1158 determine_dominators_for_sons (struct graph *g, VEC (basic_block, heap) *bbs,
1159 int y, int *son, int *brother)
1161 bitmap gprime;
1162 int i, a, nc;
1163 VEC (int, heap) **sccs;
1164 basic_block bb, dom, ybb;
1165 unsigned si;
1166 edge e;
1167 edge_iterator ei;
1169 if (son[y] == -1)
1170 return;
1171 if (y == (int) VEC_length (basic_block, bbs))
1172 ybb = ENTRY_BLOCK_PTR;
1173 else
1174 ybb = VEC_index (basic_block, bbs, y);
1176 if (brother[son[y]] == -1)
1178 /* Handle the common case Y has just one son specially. */
1179 bb = VEC_index (basic_block, bbs, son[y]);
1180 set_immediate_dominator (CDI_DOMINATORS, bb,
1181 recompute_dominator (CDI_DOMINATORS, bb));
1182 identify_vertices (g, y, son[y]);
1183 return;
1186 gprime = BITMAP_ALLOC (NULL);
1187 for (a = son[y]; a != -1; a = brother[a])
1188 bitmap_set_bit (gprime, a);
1190 nc = graphds_scc (g, gprime);
1191 BITMAP_FREE (gprime);
1193 sccs = XCNEWVEC (VEC (int, heap) *, nc);
1194 for (a = son[y]; a != -1; a = brother[a])
1195 VEC_safe_push (int, heap, sccs[g->vertices[a].component], a);
1197 for (i = nc - 1; i >= 0; i--)
1199 dom = NULL;
1200 FOR_EACH_VEC_ELT (int, sccs[i], si, a)
1202 bb = VEC_index (basic_block, bbs, a);
1203 FOR_EACH_EDGE (e, ei, bb->preds)
1205 if (root_of_dom_tree (CDI_DOMINATORS, e->src) != ybb)
1206 continue;
1208 dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src);
1212 gcc_assert (dom != NULL);
1213 FOR_EACH_VEC_ELT (int, sccs[i], si, a)
1215 bb = VEC_index (basic_block, bbs, a);
1216 set_immediate_dominator (CDI_DOMINATORS, bb, dom);
1220 for (i = 0; i < nc; i++)
1221 VEC_free (int, heap, sccs[i]);
1222 free (sccs);
1224 for (a = son[y]; a != -1; a = brother[a])
1225 identify_vertices (g, y, a);
1228 /* Recompute dominance information for basic blocks in the set BBS. The
1229 function assumes that the immediate dominators of all the other blocks
1230 in CFG are correct, and that there are no unreachable blocks.
1232 If CONSERVATIVE is true, we additionally assume that all the ancestors of
1233 a block of BBS in the current dominance tree dominate it. */
1235 void
1236 iterate_fix_dominators (enum cdi_direction dir, VEC (basic_block, heap) *bbs,
1237 bool conservative)
1239 unsigned i;
1240 basic_block bb, dom;
1241 struct graph *g;
1242 int n, y;
1243 size_t dom_i;
1244 edge e;
1245 edge_iterator ei;
1246 struct pointer_map_t *map;
1247 int *parent, *son, *brother;
1248 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1250 /* We only support updating dominators. There are some problems with
1251 updating postdominators (need to add fake edges from infinite loops
1252 and noreturn functions), and since we do not currently use
1253 iterate_fix_dominators for postdominators, any attempt to handle these
1254 problems would be unused, untested, and almost surely buggy. We keep
1255 the DIR argument for consistency with the rest of the dominator analysis
1256 interface. */
1257 gcc_checking_assert (dir == CDI_DOMINATORS && dom_computed[dir_index]);
1259 /* The algorithm we use takes inspiration from the following papers, although
1260 the details are quite different from any of them:
1262 [1] G. Ramalingam, T. Reps, An Incremental Algorithm for Maintaining the
1263 Dominator Tree of a Reducible Flowgraph
1264 [2] V. C. Sreedhar, G. R. Gao, Y.-F. Lee: Incremental computation of
1265 dominator trees
1266 [3] K. D. Cooper, T. J. Harvey and K. Kennedy: A Simple, Fast Dominance
1267 Algorithm
1269 First, we use the following heuristics to decrease the size of the BBS
1270 set:
1271 a) if BB has a single predecessor, then its immediate dominator is this
1272 predecessor
1273 additionally, if CONSERVATIVE is true:
1274 b) if all the predecessors of BB except for one (X) are dominated by BB,
1275 then X is the immediate dominator of BB
1276 c) if the nearest common ancestor of the predecessors of BB is X and
1277 X -> BB is an edge in CFG, then X is the immediate dominator of BB
1279 Then, we need to establish the dominance relation among the basic blocks
1280 in BBS. We split the dominance tree by removing the immediate dominator
1281 edges from BBS, creating a forest F. We form a graph G whose vertices
1282 are BBS and ENTRY and X -> Y is an edge of G if there exists an edge
1283 X' -> Y in CFG such that X' belongs to the tree of the dominance forest
1284 whose root is X. We then determine dominance tree of G. Note that
1285 for X, Y in BBS, X dominates Y in CFG if and only if X dominates Y in G.
1286 In this step, we can use arbitrary algorithm to determine dominators.
1287 We decided to prefer the algorithm [3] to the algorithm of
1288 Lengauer and Tarjan, since the set BBS is usually small (rarely exceeding
1289 10 during gcc bootstrap), and [3] should perform better in this case.
1291 Finally, we need to determine the immediate dominators for the basic
1292 blocks of BBS. If the immediate dominator of X in G is Y, then
1293 the immediate dominator of X in CFG belongs to the tree of F rooted in
1294 Y. We process the dominator tree T of G recursively, starting from leaves.
1295 Suppose that X_1, X_2, ..., X_k are the sons of Y in T, and that the
1296 subtrees of the dominance tree of CFG rooted in X_i are already correct.
1297 Let G' be the subgraph of G induced by {X_1, X_2, ..., X_k}. We make
1298 the following observations:
1299 (i) the immediate dominator of all blocks in a strongly connected
1300 component of G' is the same
1301 (ii) if X has no predecessors in G', then the immediate dominator of X
1302 is the nearest common ancestor of the predecessors of X in the
1303 subtree of F rooted in Y
1304 Therefore, it suffices to find the topological ordering of G', and
1305 process the nodes X_i in this order using the rules (i) and (ii).
1306 Then, we contract all the nodes X_i with Y in G, so that the further
1307 steps work correctly. */
1309 if (!conservative)
1311 /* Split the tree now. If the idoms of blocks in BBS are not
1312 conservatively correct, setting the dominators using the
1313 heuristics in prune_bbs_to_update_dominators could
1314 create cycles in the dominance "tree", and cause ICE. */
1315 FOR_EACH_VEC_ELT (basic_block, bbs, i, bb)
1316 set_immediate_dominator (CDI_DOMINATORS, bb, NULL);
1319 prune_bbs_to_update_dominators (bbs, conservative);
1320 n = VEC_length (basic_block, bbs);
1322 if (n == 0)
1323 return;
1325 if (n == 1)
1327 bb = VEC_index (basic_block, bbs, 0);
1328 set_immediate_dominator (CDI_DOMINATORS, bb,
1329 recompute_dominator (CDI_DOMINATORS, bb));
1330 return;
1333 /* Construct the graph G. */
1334 map = pointer_map_create ();
1335 FOR_EACH_VEC_ELT (basic_block, bbs, i, bb)
1337 /* If the dominance tree is conservatively correct, split it now. */
1338 if (conservative)
1339 set_immediate_dominator (CDI_DOMINATORS, bb, NULL);
1340 *pointer_map_insert (map, bb) = (void *) (size_t) i;
1342 *pointer_map_insert (map, ENTRY_BLOCK_PTR) = (void *) (size_t) n;
1344 g = new_graph (n + 1);
1345 for (y = 0; y < g->n_vertices; y++)
1346 g->vertices[y].data = BITMAP_ALLOC (NULL);
1347 FOR_EACH_VEC_ELT (basic_block, bbs, i, bb)
1349 FOR_EACH_EDGE (e, ei, bb->preds)
1351 dom = root_of_dom_tree (CDI_DOMINATORS, e->src);
1352 if (dom == bb)
1353 continue;
1355 dom_i = (size_t) *pointer_map_contains (map, dom);
1357 /* Do not include parallel edges to G. */
1358 if (!bitmap_set_bit ((bitmap) g->vertices[dom_i].data, i))
1359 continue;
1361 add_edge (g, dom_i, i);
1364 for (y = 0; y < g->n_vertices; y++)
1365 BITMAP_FREE (g->vertices[y].data);
1366 pointer_map_destroy (map);
1368 /* Find the dominator tree of G. */
1369 son = XNEWVEC (int, n + 1);
1370 brother = XNEWVEC (int, n + 1);
1371 parent = XNEWVEC (int, n + 1);
1372 graphds_domtree (g, n, parent, son, brother);
1374 /* Finally, traverse the tree and find the immediate dominators. */
1375 for (y = n; son[y] != -1; y = son[y])
1376 continue;
1377 while (y != -1)
1379 determine_dominators_for_sons (g, bbs, y, son, brother);
1381 if (brother[y] != -1)
1383 y = brother[y];
1384 while (son[y] != -1)
1385 y = son[y];
1387 else
1388 y = parent[y];
1391 free (son);
1392 free (brother);
1393 free (parent);
1395 free_graph (g);
1398 void
1399 add_to_dominance_info (enum cdi_direction dir, basic_block bb)
1401 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1403 gcc_checking_assert (dom_computed[dir_index] && !bb->dom[dir_index]);
1405 n_bbs_in_dom_tree[dir_index]++;
1407 bb->dom[dir_index] = et_new_tree (bb);
1409 if (dom_computed[dir_index] == DOM_OK)
1410 dom_computed[dir_index] = DOM_NO_FAST_QUERY;
1413 void
1414 delete_from_dominance_info (enum cdi_direction dir, basic_block bb)
1416 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1418 gcc_checking_assert (dom_computed[dir_index]);
1420 et_free_tree (bb->dom[dir_index]);
1421 bb->dom[dir_index] = NULL;
1422 n_bbs_in_dom_tree[dir_index]--;
1424 if (dom_computed[dir_index] == DOM_OK)
1425 dom_computed[dir_index] = DOM_NO_FAST_QUERY;
1428 /* Returns the first son of BB in the dominator or postdominator tree
1429 as determined by DIR. */
1431 basic_block
1432 first_dom_son (enum cdi_direction dir, basic_block bb)
1434 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1435 struct et_node *son = bb->dom[dir_index]->son;
1437 return (basic_block) (son ? son->data : NULL);
1440 /* Returns the next dominance son after BB in the dominator or postdominator
1441 tree as determined by DIR, or NULL if it was the last one. */
1443 basic_block
1444 next_dom_son (enum cdi_direction dir, basic_block bb)
1446 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1447 struct et_node *next = bb->dom[dir_index]->right;
1449 return (basic_block) (next->father->son == next ? NULL : next->data);
1452 /* Return dominance availability for dominance info DIR. */
1454 enum dom_state
1455 dom_info_state (enum cdi_direction dir)
1457 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1459 return dom_computed[dir_index];
1462 /* Set the dominance availability for dominance info DIR to NEW_STATE. */
1464 void
1465 set_dom_info_availability (enum cdi_direction dir, enum dom_state new_state)
1467 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1469 dom_computed[dir_index] = new_state;
1472 /* Returns true if dominance information for direction DIR is available. */
1474 bool
1475 dom_info_available_p (enum cdi_direction dir)
1477 unsigned int dir_index = dom_convert_dir_to_idx (dir);
1479 return dom_computed[dir_index] != DOM_NONE;
1482 DEBUG_FUNCTION void
1483 debug_dominance_info (enum cdi_direction dir)
1485 basic_block bb, bb2;
1486 FOR_EACH_BB (bb)
1487 if ((bb2 = get_immediate_dominator (dir, bb)))
1488 fprintf (stderr, "%i %i\n", bb->index, bb2->index);
1491 /* Prints to stderr representation of the dominance tree (for direction DIR)
1492 rooted in ROOT, indented by INDENT tabulators. If INDENT_FIRST is false,
1493 the first line of the output is not indented. */
1495 static void
1496 debug_dominance_tree_1 (enum cdi_direction dir, basic_block root,
1497 unsigned indent, bool indent_first)
1499 basic_block son;
1500 unsigned i;
1501 bool first = true;
1503 if (indent_first)
1504 for (i = 0; i < indent; i++)
1505 fprintf (stderr, "\t");
1506 fprintf (stderr, "%d\t", root->index);
1508 for (son = first_dom_son (dir, root);
1509 son;
1510 son = next_dom_son (dir, son))
1512 debug_dominance_tree_1 (dir, son, indent + 1, !first);
1513 first = false;
1516 if (first)
1517 fprintf (stderr, "\n");
1520 /* Prints to stderr representation of the dominance tree (for direction DIR)
1521 rooted in ROOT. */
1523 DEBUG_FUNCTION void
1524 debug_dominance_tree (enum cdi_direction dir, basic_block root)
1526 debug_dominance_tree_1 (dir, root, 0, false);