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f8032688 | 1 | /* Calculate (post)dominators in slightly super-linear time. |
c8d3e15a | 2 | Copyright (C) 2000, 2003, 2004, 2005 Free Software Foundation, Inc. |
f8032688 | 3 | Contributed by Michael Matz (matz@ifh.de). |
3a538a66 | 4 | |
1322177d | 5 | This file is part of GCC. |
3a538a66 | 6 | |
1322177d LB |
7 | GCC is free software; you can redistribute it and/or modify it |
8 | under the terms of the GNU General Public License as published by | |
f8032688 MM |
9 | the Free Software Foundation; either version 2, or (at your option) |
10 | any later version. | |
11 | ||
1322177d LB |
12 | GCC is distributed in the hope that it will be useful, but WITHOUT |
13 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY | |
14 | or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public | |
15 | License for more details. | |
f8032688 MM |
16 | |
17 | You should have received a copy of the GNU General Public License | |
1322177d | 18 | along with GCC; see the file COPYING. If not, write to the Free |
366ccddb KC |
19 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
20 | 02110-1301, USA. */ | |
f8032688 MM |
21 | |
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. | |
30 | ||
a1f300c0 | 31 | The algorithm computes this dominator tree implicitly by computing for |
f8032688 | 32 | each block its immediate dominator. We use tree balancing and path |
f3b569ca | 33 | compression, so it's the O(e*a(e,v)) variant, where a(e,v) is the very |
f8032688 MM |
34 | slowly growing functional inverse of the Ackerman function. */ |
35 | ||
36 | #include "config.h" | |
37 | #include "system.h" | |
4977bab6 ZW |
38 | #include "coretypes.h" |
39 | #include "tm.h" | |
f8032688 MM |
40 | #include "rtl.h" |
41 | #include "hard-reg-set.h" | |
7932a3db | 42 | #include "obstack.h" |
f8032688 | 43 | #include "basic-block.h" |
4c714dd4 | 44 | #include "toplev.h" |
355be0dc | 45 | #include "et-forest.h" |
f8032688 | 46 | |
d47cc544 SB |
47 | /* Whether the dominators and the postdominators are available. */ |
48 | enum dom_state dom_computed[2]; | |
f8032688 MM |
49 | |
50 | /* We name our nodes with integers, beginning with 1. Zero is reserved for | |
51 | 'undefined' or 'end of list'. The name of each node is given by the dfs | |
52 | number of the corresponding basic block. Please note, that we include the | |
53 | artificial ENTRY_BLOCK (or EXIT_BLOCK in the post-dom case) in our lists to | |
54 | support multiple entry points. As it has no real basic block index we use | |
d55bc081 | 55 | 'last_basic_block' for that. Its dfs number is of course 1. */ |
f8032688 MM |
56 | |
57 | /* Type of Basic Block aka. TBB */ | |
58 | typedef unsigned int TBB; | |
59 | ||
60 | /* We work in a poor-mans object oriented fashion, and carry an instance of | |
61 | this structure through all our 'methods'. It holds various arrays | |
62 | reflecting the (sub)structure of the flowgraph. Most of them are of type | |
63 | TBB and are also indexed by TBB. */ | |
64 | ||
65 | struct dom_info | |
66 | { | |
67 | /* The parent of a node in the DFS tree. */ | |
68 | TBB *dfs_parent; | |
69 | /* For a node x key[x] is roughly the node nearest to the root from which | |
70 | exists a way to x only over nodes behind x. Such a node is also called | |
71 | semidominator. */ | |
72 | TBB *key; | |
73 | /* The value in path_min[x] is the node y on the path from x to the root of | |
74 | the tree x is in with the smallest key[y]. */ | |
75 | TBB *path_min; | |
76 | /* bucket[x] points to the first node of the set of nodes having x as key. */ | |
77 | TBB *bucket; | |
78 | /* And next_bucket[x] points to the next node. */ | |
79 | TBB *next_bucket; | |
80 | /* After the algorithm is done, dom[x] contains the immediate dominator | |
81 | of x. */ | |
82 | TBB *dom; | |
83 | ||
84 | /* The following few fields implement the structures needed for disjoint | |
85 | sets. */ | |
86 | /* set_chain[x] is the next node on the path from x to the representant | |
87 | of the set containing x. If set_chain[x]==0 then x is a root. */ | |
88 | TBB *set_chain; | |
89 | /* set_size[x] is the number of elements in the set named by x. */ | |
90 | unsigned int *set_size; | |
91 | /* set_child[x] is used for balancing the tree representing a set. It can | |
92 | be understood as the next sibling of x. */ | |
93 | TBB *set_child; | |
94 | ||
95 | /* If b is the number of a basic block (BB->index), dfs_order[b] is the | |
96 | number of that node in DFS order counted from 1. This is an index | |
97 | into most of the other arrays in this structure. */ | |
98 | TBB *dfs_order; | |
09da1532 | 99 | /* If x is the DFS-index of a node which corresponds with a basic block, |
f8032688 MM |
100 | dfs_to_bb[x] is that basic block. Note, that in our structure there are |
101 | more nodes that basic blocks, so only dfs_to_bb[dfs_order[bb->index]]==bb | |
102 | is true for every basic block bb, but not the opposite. */ | |
103 | basic_block *dfs_to_bb; | |
104 | ||
26e0e410 | 105 | /* This is the next free DFS number when creating the DFS tree. */ |
f8032688 MM |
106 | unsigned int dfsnum; |
107 | /* The number of nodes in the DFS tree (==dfsnum-1). */ | |
108 | unsigned int nodes; | |
26e0e410 RH |
109 | |
110 | /* Blocks with bits set here have a fake edge to EXIT. These are used | |
111 | to turn a DFS forest into a proper tree. */ | |
112 | bitmap fake_exit_edge; | |
f8032688 MM |
113 | }; |
114 | ||
26e0e410 | 115 | static void init_dom_info (struct dom_info *, enum cdi_direction); |
7080f735 AJ |
116 | static void free_dom_info (struct dom_info *); |
117 | static void calc_dfs_tree_nonrec (struct dom_info *, basic_block, | |
118 | enum cdi_direction); | |
119 | static void calc_dfs_tree (struct dom_info *, enum cdi_direction); | |
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 *, enum cdi_direction); | |
d47cc544 | 124 | void debug_dominance_info (enum cdi_direction); |
f8032688 | 125 | |
6de9cd9a DN |
126 | /* Keeps track of the*/ |
127 | static unsigned n_bbs_in_dom_tree[2]; | |
128 | ||
f8032688 MM |
129 | /* Helper macro for allocating and initializing an array, |
130 | for aesthetic reasons. */ | |
131 | #define init_ar(var, type, num, content) \ | |
3a538a66 KH |
132 | do \ |
133 | { \ | |
134 | unsigned int i = 1; /* Catch content == i. */ \ | |
135 | if (! (content)) \ | |
703ad42b | 136 | (var) = xcalloc ((num), sizeof (type)); \ |
3a538a66 KH |
137 | else \ |
138 | { \ | |
703ad42b | 139 | (var) = xmalloc ((num) * sizeof (type)); \ |
3a538a66 KH |
140 | for (i = 0; i < num; i++) \ |
141 | (var)[i] = (content); \ | |
142 | } \ | |
143 | } \ | |
144 | while (0) | |
f8032688 MM |
145 | |
146 | /* Allocate all needed memory in a pessimistic fashion (so we round up). | |
4912a07c | 147 | This initializes the contents of DI, which already must be allocated. */ |
f8032688 MM |
148 | |
149 | static void | |
26e0e410 | 150 | init_dom_info (struct dom_info *di, enum cdi_direction dir) |
f8032688 | 151 | { |
0b17ab2f | 152 | /* We need memory for n_basic_blocks nodes and the ENTRY_BLOCK or |
f8032688 | 153 | EXIT_BLOCK. */ |
0b17ab2f | 154 | unsigned int num = n_basic_blocks + 1 + 1; |
f8032688 MM |
155 | init_ar (di->dfs_parent, TBB, num, 0); |
156 | init_ar (di->path_min, TBB, num, i); | |
157 | init_ar (di->key, TBB, num, i); | |
158 | init_ar (di->dom, TBB, num, 0); | |
159 | ||
160 | init_ar (di->bucket, TBB, num, 0); | |
161 | init_ar (di->next_bucket, TBB, num, 0); | |
162 | ||
163 | init_ar (di->set_chain, TBB, num, 0); | |
164 | init_ar (di->set_size, unsigned int, num, 1); | |
165 | init_ar (di->set_child, TBB, num, 0); | |
166 | ||
d55bc081 | 167 | init_ar (di->dfs_order, TBB, (unsigned int) last_basic_block + 1, 0); |
f8032688 MM |
168 | init_ar (di->dfs_to_bb, basic_block, num, 0); |
169 | ||
170 | di->dfsnum = 1; | |
171 | di->nodes = 0; | |
26e0e410 | 172 | |
8bdbfff5 | 173 | di->fake_exit_edge = dir ? BITMAP_ALLOC (NULL) : NULL; |
f8032688 MM |
174 | } |
175 | ||
176 | #undef init_ar | |
177 | ||
178 | /* Free all allocated memory in DI, but not DI itself. */ | |
179 | ||
180 | static void | |
7080f735 | 181 | free_dom_info (struct dom_info *di) |
f8032688 MM |
182 | { |
183 | free (di->dfs_parent); | |
184 | free (di->path_min); | |
185 | free (di->key); | |
186 | free (di->dom); | |
187 | free (di->bucket); | |
188 | free (di->next_bucket); | |
189 | free (di->set_chain); | |
190 | free (di->set_size); | |
191 | free (di->set_child); | |
192 | free (di->dfs_order); | |
193 | free (di->dfs_to_bb); | |
8bdbfff5 | 194 | BITMAP_FREE (di->fake_exit_edge); |
f8032688 MM |
195 | } |
196 | ||
197 | /* The nonrecursive variant of creating a DFS tree. DI is our working | |
198 | structure, BB the starting basic block for this tree and REVERSE | |
199 | is true, if predecessors should be visited instead of successors of a | |
200 | node. After this is done all nodes reachable from BB were visited, have | |
201 | assigned their dfs number and are linked together to form a tree. */ | |
202 | ||
203 | static void | |
26e0e410 RH |
204 | calc_dfs_tree_nonrec (struct dom_info *di, basic_block bb, |
205 | enum cdi_direction reverse) | |
f8032688 | 206 | { |
f8032688 MM |
207 | /* We call this _only_ if bb is not already visited. */ |
208 | edge e; | |
209 | TBB child_i, my_i = 0; | |
628f6a4e BE |
210 | edge_iterator *stack; |
211 | edge_iterator ei, einext; | |
f8032688 MM |
212 | int sp; |
213 | /* Start block (ENTRY_BLOCK_PTR for forward problem, EXIT_BLOCK for backward | |
214 | problem). */ | |
215 | basic_block en_block; | |
216 | /* Ending block. */ | |
217 | basic_block ex_block; | |
218 | ||
628f6a4e | 219 | stack = xmalloc ((n_basic_blocks + 3) * sizeof (edge_iterator)); |
f8032688 MM |
220 | sp = 0; |
221 | ||
222 | /* Initialize our border blocks, and the first edge. */ | |
223 | if (reverse) | |
224 | { | |
628f6a4e | 225 | ei = ei_start (bb->preds); |
f8032688 MM |
226 | en_block = EXIT_BLOCK_PTR; |
227 | ex_block = ENTRY_BLOCK_PTR; | |
228 | } | |
229 | else | |
230 | { | |
628f6a4e | 231 | ei = ei_start (bb->succs); |
f8032688 MM |
232 | en_block = ENTRY_BLOCK_PTR; |
233 | ex_block = EXIT_BLOCK_PTR; | |
234 | } | |
235 | ||
236 | /* When the stack is empty we break out of this loop. */ | |
237 | while (1) | |
238 | { | |
239 | basic_block bn; | |
240 | ||
241 | /* This loop traverses edges e in depth first manner, and fills the | |
242 | stack. */ | |
628f6a4e | 243 | while (!ei_end_p (ei)) |
f8032688 | 244 | { |
628f6a4e | 245 | e = ei_edge (ei); |
f8032688 MM |
246 | |
247 | /* Deduce from E the current and the next block (BB and BN), and the | |
248 | next edge. */ | |
249 | if (reverse) | |
250 | { | |
251 | bn = e->src; | |
252 | ||
253 | /* If the next node BN is either already visited or a border | |
254 | block the current edge is useless, and simply overwritten | |
255 | with the next edge out of the current node. */ | |
0b17ab2f | 256 | if (bn == ex_block || di->dfs_order[bn->index]) |
f8032688 | 257 | { |
628f6a4e | 258 | ei_next (&ei); |
f8032688 MM |
259 | continue; |
260 | } | |
261 | bb = e->dest; | |
628f6a4e | 262 | einext = ei_start (bn->preds); |
f8032688 MM |
263 | } |
264 | else | |
265 | { | |
266 | bn = e->dest; | |
0b17ab2f | 267 | if (bn == ex_block || di->dfs_order[bn->index]) |
f8032688 | 268 | { |
628f6a4e | 269 | ei_next (&ei); |
f8032688 MM |
270 | continue; |
271 | } | |
272 | bb = e->src; | |
628f6a4e | 273 | einext = ei_start (bn->succs); |
f8032688 MM |
274 | } |
275 | ||
ced3f397 | 276 | gcc_assert (bn != en_block); |
f8032688 MM |
277 | |
278 | /* Fill the DFS tree info calculatable _before_ recursing. */ | |
279 | if (bb != en_block) | |
0b17ab2f | 280 | my_i = di->dfs_order[bb->index]; |
f8032688 | 281 | else |
d55bc081 | 282 | my_i = di->dfs_order[last_basic_block]; |
0b17ab2f | 283 | child_i = di->dfs_order[bn->index] = di->dfsnum++; |
f8032688 MM |
284 | di->dfs_to_bb[child_i] = bn; |
285 | di->dfs_parent[child_i] = my_i; | |
286 | ||
287 | /* Save the current point in the CFG on the stack, and recurse. */ | |
628f6a4e BE |
288 | stack[sp++] = ei; |
289 | ei = einext; | |
f8032688 MM |
290 | } |
291 | ||
292 | if (!sp) | |
293 | break; | |
628f6a4e | 294 | ei = stack[--sp]; |
f8032688 MM |
295 | |
296 | /* OK. The edge-list was exhausted, meaning normally we would | |
297 | end the recursion. After returning from the recursive call, | |
298 | there were (may be) other statements which were run after a | |
299 | child node was completely considered by DFS. Here is the | |
300 | point to do it in the non-recursive variant. | |
301 | E.g. The block just completed is in e->dest for forward DFS, | |
302 | the block not yet completed (the parent of the one above) | |
303 | in e->src. This could be used e.g. for computing the number of | |
304 | descendants or the tree depth. */ | |
628f6a4e | 305 | ei_next (&ei); |
f8032688 MM |
306 | } |
307 | free (stack); | |
308 | } | |
309 | ||
310 | /* The main entry for calculating the DFS tree or forest. DI is our working | |
311 | structure and REVERSE is true, if we are interested in the reverse flow | |
312 | graph. In that case the result is not necessarily a tree but a forest, | |
313 | because there may be nodes from which the EXIT_BLOCK is unreachable. */ | |
314 | ||
315 | static void | |
7080f735 | 316 | calc_dfs_tree (struct dom_info *di, enum cdi_direction reverse) |
f8032688 MM |
317 | { |
318 | /* The first block is the ENTRY_BLOCK (or EXIT_BLOCK if REVERSE). */ | |
319 | basic_block begin = reverse ? EXIT_BLOCK_PTR : ENTRY_BLOCK_PTR; | |
d55bc081 | 320 | di->dfs_order[last_basic_block] = di->dfsnum; |
f8032688 MM |
321 | di->dfs_to_bb[di->dfsnum] = begin; |
322 | di->dfsnum++; | |
323 | ||
324 | calc_dfs_tree_nonrec (di, begin, reverse); | |
325 | ||
326 | if (reverse) | |
327 | { | |
328 | /* In the post-dom case we may have nodes without a path to EXIT_BLOCK. | |
329 | They are reverse-unreachable. In the dom-case we disallow such | |
26e0e410 RH |
330 | nodes, but in post-dom we have to deal with them. |
331 | ||
332 | There are two situations in which this occurs. First, noreturn | |
333 | functions. Second, infinite loops. In the first case we need to | |
334 | pretend that there is an edge to the exit block. In the second | |
335 | case, we wind up with a forest. We need to process all noreturn | |
336 | blocks before we know if we've got any infinite loops. */ | |
337 | ||
e0082a72 | 338 | basic_block b; |
26e0e410 RH |
339 | bool saw_unconnected = false; |
340 | ||
e0082a72 | 341 | FOR_EACH_BB_REVERSE (b) |
f8032688 | 342 | { |
628f6a4e | 343 | if (EDGE_COUNT (b->succs) > 0) |
26e0e410 RH |
344 | { |
345 | if (di->dfs_order[b->index] == 0) | |
346 | saw_unconnected = true; | |
347 | continue; | |
348 | } | |
349 | bitmap_set_bit (di->fake_exit_edge, b->index); | |
0b17ab2f | 350 | di->dfs_order[b->index] = di->dfsnum; |
f8032688 | 351 | di->dfs_to_bb[di->dfsnum] = b; |
26e0e410 | 352 | di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block]; |
f8032688 MM |
353 | di->dfsnum++; |
354 | calc_dfs_tree_nonrec (di, b, reverse); | |
355 | } | |
26e0e410 RH |
356 | |
357 | if (saw_unconnected) | |
358 | { | |
359 | FOR_EACH_BB_REVERSE (b) | |
360 | { | |
361 | if (di->dfs_order[b->index]) | |
362 | continue; | |
363 | bitmap_set_bit (di->fake_exit_edge, b->index); | |
364 | di->dfs_order[b->index] = di->dfsnum; | |
365 | di->dfs_to_bb[di->dfsnum] = b; | |
366 | di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block]; | |
367 | di->dfsnum++; | |
368 | calc_dfs_tree_nonrec (di, b, reverse); | |
369 | } | |
370 | } | |
f8032688 MM |
371 | } |
372 | ||
373 | di->nodes = di->dfsnum - 1; | |
374 | ||
535a42b1 | 375 | /* Make sure there is a path from ENTRY to EXIT at all. */ |
ced3f397 | 376 | gcc_assert (di->nodes == (unsigned int) n_basic_blocks + 1); |
f8032688 MM |
377 | } |
378 | ||
379 | /* Compress the path from V to the root of its set and update path_min at the | |
380 | same time. After compress(di, V) set_chain[V] is the root of the set V is | |
381 | in and path_min[V] is the node with the smallest key[] value on the path | |
382 | from V to that root. */ | |
383 | ||
384 | static void | |
7080f735 | 385 | compress (struct dom_info *di, TBB v) |
f8032688 MM |
386 | { |
387 | /* Btw. It's not worth to unrecurse compress() as the depth is usually not | |
388 | greater than 5 even for huge graphs (I've not seen call depth > 4). | |
389 | Also performance wise compress() ranges _far_ behind eval(). */ | |
390 | TBB parent = di->set_chain[v]; | |
391 | if (di->set_chain[parent]) | |
392 | { | |
393 | compress (di, parent); | |
394 | if (di->key[di->path_min[parent]] < di->key[di->path_min[v]]) | |
395 | di->path_min[v] = di->path_min[parent]; | |
396 | di->set_chain[v] = di->set_chain[parent]; | |
397 | } | |
398 | } | |
399 | ||
400 | /* Compress the path from V to the set root of V if needed (when the root has | |
401 | changed since the last call). Returns the node with the smallest key[] | |
402 | value on the path from V to the root. */ | |
403 | ||
404 | static inline TBB | |
7080f735 | 405 | eval (struct dom_info *di, TBB v) |
f8032688 MM |
406 | { |
407 | /* The representant of the set V is in, also called root (as the set | |
408 | representation is a tree). */ | |
409 | TBB rep = di->set_chain[v]; | |
410 | ||
411 | /* V itself is the root. */ | |
412 | if (!rep) | |
413 | return di->path_min[v]; | |
414 | ||
415 | /* Compress only if necessary. */ | |
416 | if (di->set_chain[rep]) | |
417 | { | |
418 | compress (di, v); | |
419 | rep = di->set_chain[v]; | |
420 | } | |
421 | ||
422 | if (di->key[di->path_min[rep]] >= di->key[di->path_min[v]]) | |
423 | return di->path_min[v]; | |
424 | else | |
425 | return di->path_min[rep]; | |
426 | } | |
427 | ||
428 | /* This essentially merges the two sets of V and W, giving a single set with | |
429 | the new root V. The internal representation of these disjoint sets is a | |
430 | balanced tree. Currently link(V,W) is only used with V being the parent | |
431 | of W. */ | |
432 | ||
433 | static void | |
7080f735 | 434 | link_roots (struct dom_info *di, TBB v, TBB w) |
f8032688 MM |
435 | { |
436 | TBB s = w; | |
437 | ||
438 | /* Rebalance the tree. */ | |
439 | while (di->key[di->path_min[w]] < di->key[di->path_min[di->set_child[s]]]) | |
440 | { | |
441 | if (di->set_size[s] + di->set_size[di->set_child[di->set_child[s]]] | |
442 | >= 2 * di->set_size[di->set_child[s]]) | |
443 | { | |
444 | di->set_chain[di->set_child[s]] = s; | |
445 | di->set_child[s] = di->set_child[di->set_child[s]]; | |
446 | } | |
447 | else | |
448 | { | |
449 | di->set_size[di->set_child[s]] = di->set_size[s]; | |
450 | s = di->set_chain[s] = di->set_child[s]; | |
451 | } | |
452 | } | |
453 | ||
454 | di->path_min[s] = di->path_min[w]; | |
455 | di->set_size[v] += di->set_size[w]; | |
456 | if (di->set_size[v] < 2 * di->set_size[w]) | |
457 | { | |
458 | TBB tmp = s; | |
459 | s = di->set_child[v]; | |
460 | di->set_child[v] = tmp; | |
461 | } | |
462 | ||
463 | /* Merge all subtrees. */ | |
464 | while (s) | |
465 | { | |
466 | di->set_chain[s] = v; | |
467 | s = di->set_child[s]; | |
468 | } | |
469 | } | |
470 | ||
471 | /* This calculates the immediate dominators (or post-dominators if REVERSE is | |
472 | true). DI is our working structure and should hold the DFS forest. | |
473 | On return the immediate dominator to node V is in di->dom[V]. */ | |
474 | ||
475 | static void | |
7080f735 | 476 | calc_idoms (struct dom_info *di, enum cdi_direction reverse) |
f8032688 MM |
477 | { |
478 | TBB v, w, k, par; | |
479 | basic_block en_block; | |
628f6a4e BE |
480 | edge_iterator ei, einext; |
481 | ||
f8032688 MM |
482 | if (reverse) |
483 | en_block = EXIT_BLOCK_PTR; | |
484 | else | |
485 | en_block = ENTRY_BLOCK_PTR; | |
486 | ||
487 | /* Go backwards in DFS order, to first look at the leafs. */ | |
488 | v = di->nodes; | |
489 | while (v > 1) | |
490 | { | |
491 | basic_block bb = di->dfs_to_bb[v]; | |
628f6a4e | 492 | edge e; |
f8032688 MM |
493 | |
494 | par = di->dfs_parent[v]; | |
495 | k = v; | |
628f6a4e BE |
496 | |
497 | ei = (reverse) ? ei_start (bb->succs) : ei_start (bb->preds); | |
498 | ||
f8032688 | 499 | if (reverse) |
26e0e410 | 500 | { |
26e0e410 RH |
501 | /* If this block has a fake edge to exit, process that first. */ |
502 | if (bitmap_bit_p (di->fake_exit_edge, bb->index)) | |
503 | { | |
628f6a4e BE |
504 | einext = ei; |
505 | einext.index = 0; | |
26e0e410 RH |
506 | goto do_fake_exit_edge; |
507 | } | |
508 | } | |
f8032688 MM |
509 | |
510 | /* Search all direct predecessors for the smallest node with a path | |
511 | to them. That way we have the smallest node with also a path to | |
512 | us only over nodes behind us. In effect we search for our | |
513 | semidominator. */ | |
628f6a4e | 514 | while (!ei_end_p (ei)) |
f8032688 MM |
515 | { |
516 | TBB k1; | |
517 | basic_block b; | |
518 | ||
628f6a4e BE |
519 | e = ei_edge (ei); |
520 | b = (reverse) ? e->dest : e->src; | |
521 | einext = ei; | |
522 | ei_next (&einext); | |
523 | ||
f8032688 | 524 | if (b == en_block) |
26e0e410 RH |
525 | { |
526 | do_fake_exit_edge: | |
527 | k1 = di->dfs_order[last_basic_block]; | |
528 | } | |
f8032688 | 529 | else |
0b17ab2f | 530 | k1 = di->dfs_order[b->index]; |
f8032688 MM |
531 | |
532 | /* Call eval() only if really needed. If k1 is above V in DFS tree, | |
533 | then we know, that eval(k1) == k1 and key[k1] == k1. */ | |
534 | if (k1 > v) | |
535 | k1 = di->key[eval (di, k1)]; | |
536 | if (k1 < k) | |
537 | k = k1; | |
628f6a4e BE |
538 | |
539 | ei = einext; | |
f8032688 MM |
540 | } |
541 | ||
542 | di->key[v] = k; | |
543 | link_roots (di, par, v); | |
544 | di->next_bucket[v] = di->bucket[k]; | |
545 | di->bucket[k] = v; | |
546 | ||
547 | /* Transform semidominators into dominators. */ | |
548 | for (w = di->bucket[par]; w; w = di->next_bucket[w]) | |
549 | { | |
550 | k = eval (di, w); | |
551 | if (di->key[k] < di->key[w]) | |
552 | di->dom[w] = k; | |
553 | else | |
554 | di->dom[w] = par; | |
555 | } | |
556 | /* We don't need to cleanup next_bucket[]. */ | |
557 | di->bucket[par] = 0; | |
558 | v--; | |
559 | } | |
560 | ||
a1f300c0 | 561 | /* Explicitly define the dominators. */ |
f8032688 MM |
562 | di->dom[1] = 0; |
563 | for (v = 2; v <= di->nodes; v++) | |
564 | if (di->dom[v] != di->key[v]) | |
565 | di->dom[v] = di->dom[di->dom[v]]; | |
566 | } | |
567 | ||
d47cc544 SB |
568 | /* Assign dfs numbers starting from NUM to NODE and its sons. */ |
569 | ||
570 | static void | |
571 | assign_dfs_numbers (struct et_node *node, int *num) | |
572 | { | |
573 | struct et_node *son; | |
574 | ||
575 | node->dfs_num_in = (*num)++; | |
576 | ||
577 | if (node->son) | |
578 | { | |
579 | assign_dfs_numbers (node->son, num); | |
580 | for (son = node->son->right; son != node->son; son = son->right) | |
6de9cd9a | 581 | assign_dfs_numbers (son, num); |
d47cc544 | 582 | } |
f8032688 | 583 | |
d47cc544 SB |
584 | node->dfs_num_out = (*num)++; |
585 | } | |
f8032688 | 586 | |
5d3cc252 | 587 | /* Compute the data necessary for fast resolving of dominator queries in a |
d47cc544 | 588 | static dominator tree. */ |
f8032688 | 589 | |
d47cc544 SB |
590 | static void |
591 | compute_dom_fast_query (enum cdi_direction dir) | |
592 | { | |
593 | int num = 0; | |
594 | basic_block bb; | |
595 | ||
fce22de5 | 596 | gcc_assert (dom_info_available_p (dir)); |
d47cc544 SB |
597 | |
598 | if (dom_computed[dir] == DOM_OK) | |
599 | return; | |
600 | ||
601 | FOR_ALL_BB (bb) | |
602 | { | |
603 | if (!bb->dom[dir]->father) | |
6de9cd9a | 604 | assign_dfs_numbers (bb->dom[dir], &num); |
d47cc544 SB |
605 | } |
606 | ||
607 | dom_computed[dir] = DOM_OK; | |
608 | } | |
609 | ||
610 | /* The main entry point into this module. DIR is set depending on whether | |
611 | we want to compute dominators or postdominators. */ | |
612 | ||
613 | void | |
614 | calculate_dominance_info (enum cdi_direction dir) | |
f8032688 MM |
615 | { |
616 | struct dom_info di; | |
355be0dc JH |
617 | basic_block b; |
618 | ||
d47cc544 SB |
619 | if (dom_computed[dir] == DOM_OK) |
620 | return; | |
355be0dc | 621 | |
fce22de5 | 622 | if (!dom_info_available_p (dir)) |
d47cc544 | 623 | { |
ced3f397 | 624 | gcc_assert (!n_bbs_in_dom_tree[dir]); |
f8032688 | 625 | |
d47cc544 SB |
626 | FOR_ALL_BB (b) |
627 | { | |
628 | b->dom[dir] = et_new_tree (b); | |
629 | } | |
6de9cd9a | 630 | n_bbs_in_dom_tree[dir] = n_basic_blocks + 2; |
f8032688 | 631 | |
26e0e410 | 632 | init_dom_info (&di, dir); |
d47cc544 SB |
633 | calc_dfs_tree (&di, dir); |
634 | calc_idoms (&di, dir); | |
355be0dc | 635 | |
d47cc544 SB |
636 | FOR_EACH_BB (b) |
637 | { | |
638 | TBB d = di.dom[di.dfs_order[b->index]]; | |
639 | ||
640 | if (di.dfs_to_bb[d]) | |
641 | et_set_father (b->dom[dir], di.dfs_to_bb[d]->dom[dir]); | |
642 | } | |
e0082a72 | 643 | |
d47cc544 SB |
644 | free_dom_info (&di); |
645 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
646 | } |
647 | ||
d47cc544 | 648 | compute_dom_fast_query (dir); |
355be0dc JH |
649 | } |
650 | ||
d47cc544 | 651 | /* Free dominance information for direction DIR. */ |
355be0dc | 652 | void |
d47cc544 | 653 | free_dominance_info (enum cdi_direction dir) |
355be0dc JH |
654 | { |
655 | basic_block bb; | |
656 | ||
fce22de5 | 657 | if (!dom_info_available_p (dir)) |
d47cc544 SB |
658 | return; |
659 | ||
660 | FOR_ALL_BB (bb) | |
661 | { | |
bef87a34 KH |
662 | et_free_tree_force (bb->dom[dir]); |
663 | bb->dom[dir] = NULL; | |
d47cc544 SB |
664 | } |
665 | ||
bef87a34 | 666 | n_bbs_in_dom_tree[dir] = 0; |
6de9cd9a | 667 | |
d47cc544 | 668 | dom_computed[dir] = DOM_NONE; |
355be0dc JH |
669 | } |
670 | ||
671 | /* Return the immediate dominator of basic block BB. */ | |
672 | basic_block | |
d47cc544 | 673 | get_immediate_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 674 | { |
d47cc544 SB |
675 | struct et_node *node = bb->dom[dir]; |
676 | ||
ced3f397 | 677 | gcc_assert (dom_computed[dir]); |
d47cc544 SB |
678 | |
679 | if (!node->father) | |
680 | return NULL; | |
681 | ||
6de9cd9a | 682 | return node->father->data; |
355be0dc JH |
683 | } |
684 | ||
685 | /* Set the immediate dominator of the block possibly removing | |
686 | existing edge. NULL can be used to remove any edge. */ | |
687 | inline void | |
d47cc544 SB |
688 | set_immediate_dominator (enum cdi_direction dir, basic_block bb, |
689 | basic_block dominated_by) | |
355be0dc | 690 | { |
d47cc544 SB |
691 | struct et_node *node = bb->dom[dir]; |
692 | ||
ced3f397 | 693 | gcc_assert (dom_computed[dir]); |
355be0dc | 694 | |
d47cc544 | 695 | if (node->father) |
355be0dc | 696 | { |
d47cc544 | 697 | if (node->father->data == dominated_by) |
6de9cd9a | 698 | return; |
d47cc544 | 699 | et_split (node); |
355be0dc | 700 | } |
d47cc544 SB |
701 | |
702 | if (dominated_by) | |
703 | et_set_father (node, dominated_by->dom[dir]); | |
704 | ||
705 | if (dom_computed[dir] == DOM_OK) | |
706 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
707 | } |
708 | ||
5d3cc252 | 709 | /* Store all basic blocks immediately dominated by BB into BBS and return |
d47cc544 | 710 | their number. */ |
355be0dc | 711 | int |
d47cc544 | 712 | get_dominated_by (enum cdi_direction dir, basic_block bb, basic_block **bbs) |
355be0dc | 713 | { |
d47cc544 SB |
714 | int n; |
715 | struct et_node *node = bb->dom[dir], *son = node->son, *ason; | |
716 | ||
ced3f397 | 717 | gcc_assert (dom_computed[dir]); |
d47cc544 SB |
718 | |
719 | if (!son) | |
720 | { | |
721 | *bbs = NULL; | |
722 | return 0; | |
723 | } | |
724 | ||
725 | for (ason = son->right, n = 1; ason != son; ason = ason->right) | |
726 | n++; | |
727 | ||
728 | *bbs = xmalloc (n * sizeof (basic_block)); | |
729 | (*bbs)[0] = son->data; | |
730 | for (ason = son->right, n = 1; ason != son; ason = ason->right) | |
731 | (*bbs)[n++] = ason->data; | |
355be0dc | 732 | |
355be0dc JH |
733 | return n; |
734 | } | |
735 | ||
42759f1e ZD |
736 | /* Find all basic blocks that are immediately dominated (in direction DIR) |
737 | by some block between N_REGION ones stored in REGION, except for blocks | |
738 | in the REGION itself. The found blocks are stored to DOMS and their number | |
739 | is returned. */ | |
740 | ||
741 | unsigned | |
742 | get_dominated_by_region (enum cdi_direction dir, basic_block *region, | |
743 | unsigned n_region, basic_block *doms) | |
744 | { | |
745 | unsigned n_doms = 0, i; | |
746 | basic_block dom; | |
747 | ||
748 | for (i = 0; i < n_region; i++) | |
6580ee77 | 749 | region[i]->flags |= BB_DUPLICATED; |
42759f1e ZD |
750 | for (i = 0; i < n_region; i++) |
751 | for (dom = first_dom_son (dir, region[i]); | |
752 | dom; | |
753 | dom = next_dom_son (dir, dom)) | |
6580ee77 | 754 | if (!(dom->flags & BB_DUPLICATED)) |
42759f1e ZD |
755 | doms[n_doms++] = dom; |
756 | for (i = 0; i < n_region; i++) | |
6580ee77 | 757 | region[i]->flags &= ~BB_DUPLICATED; |
42759f1e ZD |
758 | |
759 | return n_doms; | |
760 | } | |
761 | ||
355be0dc JH |
762 | /* Redirect all edges pointing to BB to TO. */ |
763 | void | |
d47cc544 SB |
764 | redirect_immediate_dominators (enum cdi_direction dir, basic_block bb, |
765 | basic_block to) | |
355be0dc | 766 | { |
d47cc544 SB |
767 | struct et_node *bb_node = bb->dom[dir], *to_node = to->dom[dir], *son; |
768 | ||
ced3f397 | 769 | gcc_assert (dom_computed[dir]); |
355be0dc | 770 | |
d47cc544 SB |
771 | if (!bb_node->son) |
772 | return; | |
773 | ||
774 | while (bb_node->son) | |
355be0dc | 775 | { |
d47cc544 SB |
776 | son = bb_node->son; |
777 | ||
778 | et_split (son); | |
779 | et_set_father (son, to_node); | |
355be0dc | 780 | } |
d47cc544 SB |
781 | |
782 | if (dom_computed[dir] == DOM_OK) | |
783 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
784 | } |
785 | ||
786 | /* Find first basic block in the tree dominating both BB1 and BB2. */ | |
787 | basic_block | |
d47cc544 | 788 | nearest_common_dominator (enum cdi_direction dir, basic_block bb1, basic_block bb2) |
355be0dc | 789 | { |
ced3f397 | 790 | gcc_assert (dom_computed[dir]); |
d47cc544 | 791 | |
355be0dc JH |
792 | if (!bb1) |
793 | return bb2; | |
794 | if (!bb2) | |
795 | return bb1; | |
d47cc544 SB |
796 | |
797 | return et_nca (bb1->dom[dir], bb2->dom[dir])->data; | |
355be0dc JH |
798 | } |
799 | ||
0bca51f0 DN |
800 | |
801 | /* Find the nearest common dominator for the basic blocks in BLOCKS, | |
802 | using dominance direction DIR. */ | |
803 | ||
804 | basic_block | |
805 | nearest_common_dominator_for_set (enum cdi_direction dir, bitmap blocks) | |
806 | { | |
807 | unsigned i, first; | |
808 | bitmap_iterator bi; | |
809 | basic_block dom; | |
810 | ||
811 | first = bitmap_first_set_bit (blocks); | |
812 | dom = BASIC_BLOCK (first); | |
813 | EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi) | |
814 | if (dom != BASIC_BLOCK (i)) | |
815 | dom = nearest_common_dominator (dir, dom, BASIC_BLOCK (i)); | |
816 | ||
817 | return dom; | |
818 | } | |
819 | ||
820 | ||
355be0dc JH |
821 | /* Return TRUE in case BB1 is dominated by BB2. */ |
822 | bool | |
d47cc544 | 823 | dominated_by_p (enum cdi_direction dir, basic_block bb1, basic_block bb2) |
6de9cd9a | 824 | { |
d47cc544 SB |
825 | struct et_node *n1 = bb1->dom[dir], *n2 = bb2->dom[dir]; |
826 | ||
ced3f397 | 827 | gcc_assert (dom_computed[dir]); |
d47cc544 SB |
828 | |
829 | if (dom_computed[dir] == DOM_OK) | |
830 | return (n1->dfs_num_in >= n2->dfs_num_in | |
6de9cd9a | 831 | && n1->dfs_num_out <= n2->dfs_num_out); |
d47cc544 SB |
832 | |
833 | return et_below (n1, n2); | |
355be0dc JH |
834 | } |
835 | ||
836 | /* Verify invariants of dominator structure. */ | |
837 | void | |
d47cc544 | 838 | verify_dominators (enum cdi_direction dir) |
355be0dc JH |
839 | { |
840 | int err = 0; | |
841 | basic_block bb; | |
842 | ||
fce22de5 | 843 | gcc_assert (dom_info_available_p (dir)); |
d47cc544 | 844 | |
355be0dc JH |
845 | FOR_EACH_BB (bb) |
846 | { | |
847 | basic_block dom_bb; | |
df485d80 | 848 | basic_block imm_bb; |
355be0dc | 849 | |
d47cc544 | 850 | dom_bb = recount_dominator (dir, bb); |
df485d80 FCE |
851 | imm_bb = get_immediate_dominator (dir, bb); |
852 | if (dom_bb != imm_bb) | |
f8032688 | 853 | { |
df485d80 FCE |
854 | if ((dom_bb == NULL) || (imm_bb == NULL)) |
855 | error ("dominator of %d status unknown", bb->index); | |
08fb229e FCE |
856 | else |
857 | error ("dominator of %d should be %d, not %d", | |
df485d80 | 858 | bb->index, dom_bb->index, imm_bb->index); |
355be0dc JH |
859 | err = 1; |
860 | } | |
861 | } | |
e7bd94cc | 862 | |
fce22de5 | 863 | if (dir == CDI_DOMINATORS) |
e7bd94cc ZD |
864 | { |
865 | FOR_EACH_BB (bb) | |
866 | { | |
867 | if (!dominated_by_p (dir, bb, ENTRY_BLOCK_PTR)) | |
868 | { | |
869 | error ("ENTRY does not dominate bb %d", bb->index); | |
870 | err = 1; | |
871 | } | |
872 | } | |
873 | } | |
874 | ||
ced3f397 | 875 | gcc_assert (!err); |
355be0dc JH |
876 | } |
877 | ||
738ed977 ZD |
878 | /* Determine immediate dominator (or postdominator, according to DIR) of BB, |
879 | assuming that dominators of other blocks are correct. We also use it to | |
880 | recompute the dominators in a restricted area, by iterating it until it | |
71cc389b | 881 | reaches a fixed point. */ |
738ed977 | 882 | |
355be0dc | 883 | basic_block |
d47cc544 | 884 | recount_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 885 | { |
738ed977 ZD |
886 | basic_block dom_bb = NULL; |
887 | edge e; | |
628f6a4e | 888 | edge_iterator ei; |
355be0dc | 889 | |
ced3f397 | 890 | gcc_assert (dom_computed[dir]); |
d47cc544 | 891 | |
738ed977 ZD |
892 | if (dir == CDI_DOMINATORS) |
893 | { | |
628f6a4e | 894 | FOR_EACH_EDGE (e, ei, bb->preds) |
738ed977 | 895 | { |
e7bd94cc ZD |
896 | /* Ignore the predecessors that either are not reachable from |
897 | the entry block, or whose dominator was not determined yet. */ | |
898 | if (!dominated_by_p (dir, e->src, ENTRY_BLOCK_PTR)) | |
899 | continue; | |
900 | ||
738ed977 ZD |
901 | if (!dominated_by_p (dir, e->src, bb)) |
902 | dom_bb = nearest_common_dominator (dir, dom_bb, e->src); | |
903 | } | |
904 | } | |
905 | else | |
906 | { | |
628f6a4e | 907 | FOR_EACH_EDGE (e, ei, bb->succs) |
738ed977 ZD |
908 | { |
909 | if (!dominated_by_p (dir, e->dest, bb)) | |
910 | dom_bb = nearest_common_dominator (dir, dom_bb, e->dest); | |
911 | } | |
912 | } | |
f8032688 | 913 | |
738ed977 | 914 | return dom_bb; |
355be0dc JH |
915 | } |
916 | ||
917 | /* Iteratively recount dominators of BBS. The change is supposed to be local | |
918 | and not to grow further. */ | |
919 | void | |
d47cc544 | 920 | iterate_fix_dominators (enum cdi_direction dir, basic_block *bbs, int n) |
355be0dc JH |
921 | { |
922 | int i, changed = 1; | |
923 | basic_block old_dom, new_dom; | |
924 | ||
ced3f397 | 925 | gcc_assert (dom_computed[dir]); |
d47cc544 | 926 | |
e7bd94cc ZD |
927 | for (i = 0; i < n; i++) |
928 | set_immediate_dominator (dir, bbs[i], NULL); | |
929 | ||
355be0dc JH |
930 | while (changed) |
931 | { | |
932 | changed = 0; | |
933 | for (i = 0; i < n; i++) | |
934 | { | |
d47cc544 SB |
935 | old_dom = get_immediate_dominator (dir, bbs[i]); |
936 | new_dom = recount_dominator (dir, bbs[i]); | |
355be0dc JH |
937 | if (old_dom != new_dom) |
938 | { | |
939 | changed = 1; | |
d47cc544 | 940 | set_immediate_dominator (dir, bbs[i], new_dom); |
355be0dc | 941 | } |
f8032688 MM |
942 | } |
943 | } | |
e7bd94cc ZD |
944 | |
945 | for (i = 0; i < n; i++) | |
ced3f397 | 946 | gcc_assert (get_immediate_dominator (dir, bbs[i])); |
355be0dc | 947 | } |
f8032688 | 948 | |
355be0dc | 949 | void |
d47cc544 | 950 | add_to_dominance_info (enum cdi_direction dir, basic_block bb) |
355be0dc | 951 | { |
ced3f397 NS |
952 | gcc_assert (dom_computed[dir]); |
953 | gcc_assert (!bb->dom[dir]); | |
d47cc544 | 954 | |
6de9cd9a DN |
955 | n_bbs_in_dom_tree[dir]++; |
956 | ||
d47cc544 SB |
957 | bb->dom[dir] = et_new_tree (bb); |
958 | ||
959 | if (dom_computed[dir] == DOM_OK) | |
960 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
961 | } |
962 | ||
963 | void | |
d47cc544 SB |
964 | delete_from_dominance_info (enum cdi_direction dir, basic_block bb) |
965 | { | |
ced3f397 | 966 | gcc_assert (dom_computed[dir]); |
d47cc544 SB |
967 | |
968 | et_free_tree (bb->dom[dir]); | |
969 | bb->dom[dir] = NULL; | |
6de9cd9a | 970 | n_bbs_in_dom_tree[dir]--; |
d47cc544 SB |
971 | |
972 | if (dom_computed[dir] == DOM_OK) | |
973 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
974 | } | |
975 | ||
976 | /* Returns the first son of BB in the dominator or postdominator tree | |
977 | as determined by DIR. */ | |
978 | ||
979 | basic_block | |
980 | first_dom_son (enum cdi_direction dir, basic_block bb) | |
355be0dc | 981 | { |
d47cc544 SB |
982 | struct et_node *son = bb->dom[dir]->son; |
983 | ||
984 | return son ? son->data : NULL; | |
985 | } | |
986 | ||
987 | /* Returns the next dominance son after BB in the dominator or postdominator | |
988 | tree as determined by DIR, or NULL if it was the last one. */ | |
989 | ||
990 | basic_block | |
991 | next_dom_son (enum cdi_direction dir, basic_block bb) | |
992 | { | |
993 | struct et_node *next = bb->dom[dir]->right; | |
994 | ||
995 | return next->father->son == next ? NULL : next->data; | |
355be0dc JH |
996 | } |
997 | ||
fce22de5 ZD |
998 | /* Returns true if dominance information for direction DIR is available. */ |
999 | ||
1000 | bool | |
1001 | dom_info_available_p (enum cdi_direction dir) | |
1002 | { | |
1003 | return dom_computed[dir] != DOM_NONE; | |
1004 | } | |
1005 | ||
355be0dc | 1006 | void |
d47cc544 | 1007 | debug_dominance_info (enum cdi_direction dir) |
355be0dc JH |
1008 | { |
1009 | basic_block bb, bb2; | |
1010 | FOR_EACH_BB (bb) | |
d47cc544 | 1011 | if ((bb2 = get_immediate_dominator (dir, bb))) |
355be0dc | 1012 | fprintf (stderr, "%i %i\n", bb->index, bb2->index); |
f8032688 | 1013 | } |