]>
Commit | Line | Data |
---|---|---|
f8032688 | 1 | /* Calculate (post)dominators in slightly super-linear time. |
d9221e01 | 2 | Copyright (C) 2000, 2003, 2004 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 LB |
18 | along with GCC; see the file COPYING. If not, write to the Free |
19 | Software Foundation, 59 Temple Place - Suite 330, Boston, MA | |
20 | 02111-1307, 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 MM |
32 | each block its immediate dominator. We use tree balancing and path |
33 | compression, so its the O(e*a(e,v)) variant, where a(e,v) is the very | |
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" | |
42 | #include "basic-block.h" | |
8a67e083 | 43 | #include "errors.h" |
355be0dc | 44 | #include "et-forest.h" |
f8032688 | 45 | |
d47cc544 SB |
46 | /* Whether the dominators and the postdominators are available. */ |
47 | enum dom_state dom_computed[2]; | |
f8032688 MM |
48 | |
49 | /* We name our nodes with integers, beginning with 1. Zero is reserved for | |
50 | 'undefined' or 'end of list'. The name of each node is given by the dfs | |
51 | number of the corresponding basic block. Please note, that we include the | |
52 | artificial ENTRY_BLOCK (or EXIT_BLOCK in the post-dom case) in our lists to | |
53 | support multiple entry points. As it has no real basic block index we use | |
d55bc081 | 54 | 'last_basic_block' for that. Its dfs number is of course 1. */ |
f8032688 MM |
55 | |
56 | /* Type of Basic Block aka. TBB */ | |
57 | typedef unsigned int TBB; | |
58 | ||
59 | /* We work in a poor-mans object oriented fashion, and carry an instance of | |
60 | this structure through all our 'methods'. It holds various arrays | |
61 | reflecting the (sub)structure of the flowgraph. Most of them are of type | |
62 | TBB and are also indexed by TBB. */ | |
63 | ||
64 | struct dom_info | |
65 | { | |
66 | /* The parent of a node in the DFS tree. */ | |
67 | TBB *dfs_parent; | |
68 | /* For a node x key[x] is roughly the node nearest to the root from which | |
69 | exists a way to x only over nodes behind x. Such a node is also called | |
70 | semidominator. */ | |
71 | TBB *key; | |
72 | /* The value in path_min[x] is the node y on the path from x to the root of | |
73 | the tree x is in with the smallest key[y]. */ | |
74 | TBB *path_min; | |
75 | /* bucket[x] points to the first node of the set of nodes having x as key. */ | |
76 | TBB *bucket; | |
77 | /* And next_bucket[x] points to the next node. */ | |
78 | TBB *next_bucket; | |
79 | /* After the algorithm is done, dom[x] contains the immediate dominator | |
80 | of x. */ | |
81 | TBB *dom; | |
82 | ||
83 | /* The following few fields implement the structures needed for disjoint | |
84 | sets. */ | |
85 | /* set_chain[x] is the next node on the path from x to the representant | |
86 | of the set containing x. If set_chain[x]==0 then x is a root. */ | |
87 | TBB *set_chain; | |
88 | /* set_size[x] is the number of elements in the set named by x. */ | |
89 | unsigned int *set_size; | |
90 | /* set_child[x] is used for balancing the tree representing a set. It can | |
91 | be understood as the next sibling of x. */ | |
92 | TBB *set_child; | |
93 | ||
94 | /* If b is the number of a basic block (BB->index), dfs_order[b] is the | |
95 | number of that node in DFS order counted from 1. This is an index | |
96 | into most of the other arrays in this structure. */ | |
97 | TBB *dfs_order; | |
09da1532 | 98 | /* If x is the DFS-index of a node which corresponds with a basic block, |
f8032688 MM |
99 | dfs_to_bb[x] is that basic block. Note, that in our structure there are |
100 | more nodes that basic blocks, so only dfs_to_bb[dfs_order[bb->index]]==bb | |
101 | is true for every basic block bb, but not the opposite. */ | |
102 | basic_block *dfs_to_bb; | |
103 | ||
30f7a378 | 104 | /* This is the next free DFS number when creating the DFS tree or forest. */ |
f8032688 MM |
105 | unsigned int dfsnum; |
106 | /* The number of nodes in the DFS tree (==dfsnum-1). */ | |
107 | unsigned int nodes; | |
108 | }; | |
109 | ||
7080f735 AJ |
110 | static void init_dom_info (struct dom_info *); |
111 | static void free_dom_info (struct dom_info *); | |
112 | static void calc_dfs_tree_nonrec (struct dom_info *, basic_block, | |
113 | enum cdi_direction); | |
114 | static void calc_dfs_tree (struct dom_info *, enum cdi_direction); | |
115 | static void compress (struct dom_info *, TBB); | |
116 | static TBB eval (struct dom_info *, TBB); | |
117 | static void link_roots (struct dom_info *, TBB, TBB); | |
118 | static void calc_idoms (struct dom_info *, enum cdi_direction); | |
d47cc544 | 119 | void debug_dominance_info (enum cdi_direction); |
f8032688 MM |
120 | |
121 | /* Helper macro for allocating and initializing an array, | |
122 | for aesthetic reasons. */ | |
123 | #define init_ar(var, type, num, content) \ | |
3a538a66 KH |
124 | do \ |
125 | { \ | |
126 | unsigned int i = 1; /* Catch content == i. */ \ | |
127 | if (! (content)) \ | |
703ad42b | 128 | (var) = xcalloc ((num), sizeof (type)); \ |
3a538a66 KH |
129 | else \ |
130 | { \ | |
703ad42b | 131 | (var) = xmalloc ((num) * sizeof (type)); \ |
3a538a66 KH |
132 | for (i = 0; i < num; i++) \ |
133 | (var)[i] = (content); \ | |
134 | } \ | |
135 | } \ | |
136 | while (0) | |
f8032688 MM |
137 | |
138 | /* Allocate all needed memory in a pessimistic fashion (so we round up). | |
4912a07c | 139 | This initializes the contents of DI, which already must be allocated. */ |
f8032688 MM |
140 | |
141 | static void | |
7080f735 | 142 | init_dom_info (struct dom_info *di) |
f8032688 | 143 | { |
0b17ab2f | 144 | /* We need memory for n_basic_blocks nodes and the ENTRY_BLOCK or |
f8032688 | 145 | EXIT_BLOCK. */ |
0b17ab2f | 146 | unsigned int num = n_basic_blocks + 1 + 1; |
f8032688 MM |
147 | init_ar (di->dfs_parent, TBB, num, 0); |
148 | init_ar (di->path_min, TBB, num, i); | |
149 | init_ar (di->key, TBB, num, i); | |
150 | init_ar (di->dom, TBB, num, 0); | |
151 | ||
152 | init_ar (di->bucket, TBB, num, 0); | |
153 | init_ar (di->next_bucket, TBB, num, 0); | |
154 | ||
155 | init_ar (di->set_chain, TBB, num, 0); | |
156 | init_ar (di->set_size, unsigned int, num, 1); | |
157 | init_ar (di->set_child, TBB, num, 0); | |
158 | ||
d55bc081 | 159 | init_ar (di->dfs_order, TBB, (unsigned int) last_basic_block + 1, 0); |
f8032688 MM |
160 | init_ar (di->dfs_to_bb, basic_block, num, 0); |
161 | ||
162 | di->dfsnum = 1; | |
163 | di->nodes = 0; | |
164 | } | |
165 | ||
166 | #undef init_ar | |
167 | ||
168 | /* Free all allocated memory in DI, but not DI itself. */ | |
169 | ||
170 | static void | |
7080f735 | 171 | free_dom_info (struct dom_info *di) |
f8032688 MM |
172 | { |
173 | free (di->dfs_parent); | |
174 | free (di->path_min); | |
175 | free (di->key); | |
176 | free (di->dom); | |
177 | free (di->bucket); | |
178 | free (di->next_bucket); | |
179 | free (di->set_chain); | |
180 | free (di->set_size); | |
181 | free (di->set_child); | |
182 | free (di->dfs_order); | |
183 | free (di->dfs_to_bb); | |
184 | } | |
185 | ||
186 | /* The nonrecursive variant of creating a DFS tree. DI is our working | |
187 | structure, BB the starting basic block for this tree and REVERSE | |
188 | is true, if predecessors should be visited instead of successors of a | |
189 | node. After this is done all nodes reachable from BB were visited, have | |
190 | assigned their dfs number and are linked together to form a tree. */ | |
191 | ||
192 | static void | |
7080f735 | 193 | calc_dfs_tree_nonrec (struct dom_info *di, basic_block bb, enum cdi_direction reverse) |
f8032688 | 194 | { |
30f7a378 | 195 | /* We never call this with bb==EXIT_BLOCK_PTR (ENTRY_BLOCK_PTR if REVERSE). */ |
f8032688 MM |
196 | /* We call this _only_ if bb is not already visited. */ |
197 | edge e; | |
198 | TBB child_i, my_i = 0; | |
199 | edge *stack; | |
200 | int sp; | |
201 | /* Start block (ENTRY_BLOCK_PTR for forward problem, EXIT_BLOCK for backward | |
202 | problem). */ | |
203 | basic_block en_block; | |
204 | /* Ending block. */ | |
205 | basic_block ex_block; | |
206 | ||
703ad42b | 207 | stack = xmalloc ((n_basic_blocks + 3) * sizeof (edge)); |
f8032688 MM |
208 | sp = 0; |
209 | ||
210 | /* Initialize our border blocks, and the first edge. */ | |
211 | if (reverse) | |
212 | { | |
213 | e = bb->pred; | |
214 | en_block = EXIT_BLOCK_PTR; | |
215 | ex_block = ENTRY_BLOCK_PTR; | |
216 | } | |
217 | else | |
218 | { | |
219 | e = bb->succ; | |
220 | en_block = ENTRY_BLOCK_PTR; | |
221 | ex_block = EXIT_BLOCK_PTR; | |
222 | } | |
223 | ||
224 | /* When the stack is empty we break out of this loop. */ | |
225 | while (1) | |
226 | { | |
227 | basic_block bn; | |
228 | ||
229 | /* This loop traverses edges e in depth first manner, and fills the | |
230 | stack. */ | |
231 | while (e) | |
232 | { | |
233 | edge e_next; | |
234 | ||
235 | /* Deduce from E the current and the next block (BB and BN), and the | |
236 | next edge. */ | |
237 | if (reverse) | |
238 | { | |
239 | bn = e->src; | |
240 | ||
241 | /* If the next node BN is either already visited or a border | |
242 | block the current edge is useless, and simply overwritten | |
243 | with the next edge out of the current node. */ | |
0b17ab2f | 244 | if (bn == ex_block || di->dfs_order[bn->index]) |
f8032688 MM |
245 | { |
246 | e = e->pred_next; | |
247 | continue; | |
248 | } | |
249 | bb = e->dest; | |
250 | e_next = bn->pred; | |
251 | } | |
252 | else | |
253 | { | |
254 | bn = e->dest; | |
0b17ab2f | 255 | if (bn == ex_block || di->dfs_order[bn->index]) |
f8032688 MM |
256 | { |
257 | e = e->succ_next; | |
258 | continue; | |
259 | } | |
260 | bb = e->src; | |
261 | e_next = bn->succ; | |
262 | } | |
263 | ||
264 | if (bn == en_block) | |
265 | abort (); | |
266 | ||
267 | /* Fill the DFS tree info calculatable _before_ recursing. */ | |
268 | if (bb != en_block) | |
0b17ab2f | 269 | my_i = di->dfs_order[bb->index]; |
f8032688 | 270 | else |
d55bc081 | 271 | my_i = di->dfs_order[last_basic_block]; |
0b17ab2f | 272 | child_i = di->dfs_order[bn->index] = di->dfsnum++; |
f8032688 MM |
273 | di->dfs_to_bb[child_i] = bn; |
274 | di->dfs_parent[child_i] = my_i; | |
275 | ||
276 | /* Save the current point in the CFG on the stack, and recurse. */ | |
277 | stack[sp++] = e; | |
278 | e = e_next; | |
279 | } | |
280 | ||
281 | if (!sp) | |
282 | break; | |
283 | e = stack[--sp]; | |
284 | ||
285 | /* OK. The edge-list was exhausted, meaning normally we would | |
286 | end the recursion. After returning from the recursive call, | |
287 | there were (may be) other statements which were run after a | |
288 | child node was completely considered by DFS. Here is the | |
289 | point to do it in the non-recursive variant. | |
290 | E.g. The block just completed is in e->dest for forward DFS, | |
291 | the block not yet completed (the parent of the one above) | |
292 | in e->src. This could be used e.g. for computing the number of | |
293 | descendants or the tree depth. */ | |
294 | if (reverse) | |
295 | e = e->pred_next; | |
296 | else | |
297 | e = e->succ_next; | |
298 | } | |
299 | free (stack); | |
300 | } | |
301 | ||
302 | /* The main entry for calculating the DFS tree or forest. DI is our working | |
303 | structure and REVERSE is true, if we are interested in the reverse flow | |
304 | graph. In that case the result is not necessarily a tree but a forest, | |
305 | because there may be nodes from which the EXIT_BLOCK is unreachable. */ | |
306 | ||
307 | static void | |
7080f735 | 308 | calc_dfs_tree (struct dom_info *di, enum cdi_direction reverse) |
f8032688 MM |
309 | { |
310 | /* The first block is the ENTRY_BLOCK (or EXIT_BLOCK if REVERSE). */ | |
311 | basic_block begin = reverse ? EXIT_BLOCK_PTR : ENTRY_BLOCK_PTR; | |
d55bc081 | 312 | di->dfs_order[last_basic_block] = di->dfsnum; |
f8032688 MM |
313 | di->dfs_to_bb[di->dfsnum] = begin; |
314 | di->dfsnum++; | |
315 | ||
316 | calc_dfs_tree_nonrec (di, begin, reverse); | |
317 | ||
318 | if (reverse) | |
319 | { | |
320 | /* In the post-dom case we may have nodes without a path to EXIT_BLOCK. | |
321 | They are reverse-unreachable. In the dom-case we disallow such | |
322 | nodes, but in post-dom we have to deal with them, so we simply | |
323 | include them in the DFS tree which actually becomes a forest. */ | |
e0082a72 ZD |
324 | basic_block b; |
325 | FOR_EACH_BB_REVERSE (b) | |
f8032688 | 326 | { |
0b17ab2f | 327 | if (di->dfs_order[b->index]) |
f8032688 | 328 | continue; |
0b17ab2f | 329 | di->dfs_order[b->index] = di->dfsnum; |
f8032688 MM |
330 | di->dfs_to_bb[di->dfsnum] = b; |
331 | di->dfsnum++; | |
332 | calc_dfs_tree_nonrec (di, b, reverse); | |
333 | } | |
334 | } | |
335 | ||
336 | di->nodes = di->dfsnum - 1; | |
337 | ||
338 | /* This aborts e.g. when there is _no_ path from ENTRY to EXIT at all. */ | |
0b17ab2f | 339 | if (di->nodes != (unsigned int) n_basic_blocks + 1) |
f8032688 MM |
340 | abort (); |
341 | } | |
342 | ||
343 | /* Compress the path from V to the root of its set and update path_min at the | |
344 | same time. After compress(di, V) set_chain[V] is the root of the set V is | |
345 | in and path_min[V] is the node with the smallest key[] value on the path | |
346 | from V to that root. */ | |
347 | ||
348 | static void | |
7080f735 | 349 | compress (struct dom_info *di, TBB v) |
f8032688 MM |
350 | { |
351 | /* Btw. It's not worth to unrecurse compress() as the depth is usually not | |
352 | greater than 5 even for huge graphs (I've not seen call depth > 4). | |
353 | Also performance wise compress() ranges _far_ behind eval(). */ | |
354 | TBB parent = di->set_chain[v]; | |
355 | if (di->set_chain[parent]) | |
356 | { | |
357 | compress (di, parent); | |
358 | if (di->key[di->path_min[parent]] < di->key[di->path_min[v]]) | |
359 | di->path_min[v] = di->path_min[parent]; | |
360 | di->set_chain[v] = di->set_chain[parent]; | |
361 | } | |
362 | } | |
363 | ||
364 | /* Compress the path from V to the set root of V if needed (when the root has | |
365 | changed since the last call). Returns the node with the smallest key[] | |
366 | value on the path from V to the root. */ | |
367 | ||
368 | static inline TBB | |
7080f735 | 369 | eval (struct dom_info *di, TBB v) |
f8032688 MM |
370 | { |
371 | /* The representant of the set V is in, also called root (as the set | |
372 | representation is a tree). */ | |
373 | TBB rep = di->set_chain[v]; | |
374 | ||
375 | /* V itself is the root. */ | |
376 | if (!rep) | |
377 | return di->path_min[v]; | |
378 | ||
379 | /* Compress only if necessary. */ | |
380 | if (di->set_chain[rep]) | |
381 | { | |
382 | compress (di, v); | |
383 | rep = di->set_chain[v]; | |
384 | } | |
385 | ||
386 | if (di->key[di->path_min[rep]] >= di->key[di->path_min[v]]) | |
387 | return di->path_min[v]; | |
388 | else | |
389 | return di->path_min[rep]; | |
390 | } | |
391 | ||
392 | /* This essentially merges the two sets of V and W, giving a single set with | |
393 | the new root V. The internal representation of these disjoint sets is a | |
394 | balanced tree. Currently link(V,W) is only used with V being the parent | |
395 | of W. */ | |
396 | ||
397 | static void | |
7080f735 | 398 | link_roots (struct dom_info *di, TBB v, TBB w) |
f8032688 MM |
399 | { |
400 | TBB s = w; | |
401 | ||
402 | /* Rebalance the tree. */ | |
403 | while (di->key[di->path_min[w]] < di->key[di->path_min[di->set_child[s]]]) | |
404 | { | |
405 | if (di->set_size[s] + di->set_size[di->set_child[di->set_child[s]]] | |
406 | >= 2 * di->set_size[di->set_child[s]]) | |
407 | { | |
408 | di->set_chain[di->set_child[s]] = s; | |
409 | di->set_child[s] = di->set_child[di->set_child[s]]; | |
410 | } | |
411 | else | |
412 | { | |
413 | di->set_size[di->set_child[s]] = di->set_size[s]; | |
414 | s = di->set_chain[s] = di->set_child[s]; | |
415 | } | |
416 | } | |
417 | ||
418 | di->path_min[s] = di->path_min[w]; | |
419 | di->set_size[v] += di->set_size[w]; | |
420 | if (di->set_size[v] < 2 * di->set_size[w]) | |
421 | { | |
422 | TBB tmp = s; | |
423 | s = di->set_child[v]; | |
424 | di->set_child[v] = tmp; | |
425 | } | |
426 | ||
427 | /* Merge all subtrees. */ | |
428 | while (s) | |
429 | { | |
430 | di->set_chain[s] = v; | |
431 | s = di->set_child[s]; | |
432 | } | |
433 | } | |
434 | ||
435 | /* This calculates the immediate dominators (or post-dominators if REVERSE is | |
436 | true). DI is our working structure and should hold the DFS forest. | |
437 | On return the immediate dominator to node V is in di->dom[V]. */ | |
438 | ||
439 | static void | |
7080f735 | 440 | calc_idoms (struct dom_info *di, enum cdi_direction reverse) |
f8032688 MM |
441 | { |
442 | TBB v, w, k, par; | |
443 | basic_block en_block; | |
444 | if (reverse) | |
445 | en_block = EXIT_BLOCK_PTR; | |
446 | else | |
447 | en_block = ENTRY_BLOCK_PTR; | |
448 | ||
449 | /* Go backwards in DFS order, to first look at the leafs. */ | |
450 | v = di->nodes; | |
451 | while (v > 1) | |
452 | { | |
453 | basic_block bb = di->dfs_to_bb[v]; | |
454 | edge e, e_next; | |
455 | ||
456 | par = di->dfs_parent[v]; | |
457 | k = v; | |
458 | if (reverse) | |
459 | e = bb->succ; | |
460 | else | |
461 | e = bb->pred; | |
462 | ||
463 | /* Search all direct predecessors for the smallest node with a path | |
464 | to them. That way we have the smallest node with also a path to | |
465 | us only over nodes behind us. In effect we search for our | |
466 | semidominator. */ | |
467 | for (; e; e = e_next) | |
468 | { | |
469 | TBB k1; | |
470 | basic_block b; | |
471 | ||
472 | if (reverse) | |
473 | { | |
474 | b = e->dest; | |
475 | e_next = e->succ_next; | |
476 | } | |
477 | else | |
478 | { | |
479 | b = e->src; | |
480 | e_next = e->pred_next; | |
481 | } | |
482 | if (b == en_block) | |
d55bc081 | 483 | k1 = di->dfs_order[last_basic_block]; |
f8032688 | 484 | else |
0b17ab2f | 485 | k1 = di->dfs_order[b->index]; |
f8032688 MM |
486 | |
487 | /* Call eval() only if really needed. If k1 is above V in DFS tree, | |
488 | then we know, that eval(k1) == k1 and key[k1] == k1. */ | |
489 | if (k1 > v) | |
490 | k1 = di->key[eval (di, k1)]; | |
491 | if (k1 < k) | |
492 | k = k1; | |
493 | } | |
494 | ||
495 | di->key[v] = k; | |
496 | link_roots (di, par, v); | |
497 | di->next_bucket[v] = di->bucket[k]; | |
498 | di->bucket[k] = v; | |
499 | ||
500 | /* Transform semidominators into dominators. */ | |
501 | for (w = di->bucket[par]; w; w = di->next_bucket[w]) | |
502 | { | |
503 | k = eval (di, w); | |
504 | if (di->key[k] < di->key[w]) | |
505 | di->dom[w] = k; | |
506 | else | |
507 | di->dom[w] = par; | |
508 | } | |
509 | /* We don't need to cleanup next_bucket[]. */ | |
510 | di->bucket[par] = 0; | |
511 | v--; | |
512 | } | |
513 | ||
a1f300c0 | 514 | /* Explicitly define the dominators. */ |
f8032688 MM |
515 | di->dom[1] = 0; |
516 | for (v = 2; v <= di->nodes; v++) | |
517 | if (di->dom[v] != di->key[v]) | |
518 | di->dom[v] = di->dom[di->dom[v]]; | |
519 | } | |
520 | ||
d47cc544 SB |
521 | /* Assign dfs numbers starting from NUM to NODE and its sons. */ |
522 | ||
523 | static void | |
524 | assign_dfs_numbers (struct et_node *node, int *num) | |
525 | { | |
526 | struct et_node *son; | |
527 | ||
528 | node->dfs_num_in = (*num)++; | |
529 | ||
530 | if (node->son) | |
531 | { | |
532 | assign_dfs_numbers (node->son, num); | |
533 | for (son = node->son->right; son != node->son; son = son->right) | |
534 | assign_dfs_numbers (son, num); | |
535 | } | |
f8032688 | 536 | |
d47cc544 SB |
537 | node->dfs_num_out = (*num)++; |
538 | } | |
f8032688 | 539 | |
5d3cc252 | 540 | /* Compute the data necessary for fast resolving of dominator queries in a |
d47cc544 | 541 | static dominator tree. */ |
f8032688 | 542 | |
d47cc544 SB |
543 | static void |
544 | compute_dom_fast_query (enum cdi_direction dir) | |
545 | { | |
546 | int num = 0; | |
547 | basic_block bb; | |
548 | ||
549 | if (dom_computed[dir] < DOM_NO_FAST_QUERY) | |
550 | abort (); | |
551 | ||
552 | if (dom_computed[dir] == DOM_OK) | |
553 | return; | |
554 | ||
555 | FOR_ALL_BB (bb) | |
556 | { | |
557 | if (!bb->dom[dir]->father) | |
558 | assign_dfs_numbers (bb->dom[dir], &num); | |
559 | } | |
560 | ||
561 | dom_computed[dir] = DOM_OK; | |
562 | } | |
563 | ||
564 | /* The main entry point into this module. DIR is set depending on whether | |
565 | we want to compute dominators or postdominators. */ | |
566 | ||
567 | void | |
568 | calculate_dominance_info (enum cdi_direction dir) | |
f8032688 MM |
569 | { |
570 | struct dom_info di; | |
355be0dc JH |
571 | basic_block b; |
572 | ||
d47cc544 SB |
573 | if (dom_computed[dir] == DOM_OK) |
574 | return; | |
355be0dc | 575 | |
d47cc544 SB |
576 | if (dom_computed[dir] != DOM_NO_FAST_QUERY) |
577 | { | |
578 | if (dom_computed[dir] != DOM_NONE) | |
579 | free_dominance_info (dir); | |
f8032688 | 580 | |
d47cc544 SB |
581 | FOR_ALL_BB (b) |
582 | { | |
583 | b->dom[dir] = et_new_tree (b); | |
584 | } | |
f8032688 | 585 | |
d47cc544 SB |
586 | init_dom_info (&di); |
587 | calc_dfs_tree (&di, dir); | |
588 | calc_idoms (&di, dir); | |
355be0dc | 589 | |
d47cc544 SB |
590 | FOR_EACH_BB (b) |
591 | { | |
592 | TBB d = di.dom[di.dfs_order[b->index]]; | |
593 | ||
594 | if (di.dfs_to_bb[d]) | |
595 | et_set_father (b->dom[dir], di.dfs_to_bb[d]->dom[dir]); | |
596 | } | |
e0082a72 | 597 | |
d47cc544 SB |
598 | free_dom_info (&di); |
599 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
600 | } |
601 | ||
d47cc544 | 602 | compute_dom_fast_query (dir); |
355be0dc JH |
603 | } |
604 | ||
d47cc544 | 605 | /* Free dominance information for direction DIR. */ |
355be0dc | 606 | void |
d47cc544 | 607 | free_dominance_info (enum cdi_direction dir) |
355be0dc JH |
608 | { |
609 | basic_block bb; | |
610 | ||
d47cc544 SB |
611 | if (!dom_computed[dir]) |
612 | return; | |
613 | ||
614 | FOR_ALL_BB (bb) | |
615 | { | |
616 | delete_from_dominance_info (dir, bb); | |
617 | } | |
618 | ||
619 | dom_computed[dir] = DOM_NONE; | |
355be0dc JH |
620 | } |
621 | ||
622 | /* Return the immediate dominator of basic block BB. */ | |
623 | basic_block | |
d47cc544 | 624 | get_immediate_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 625 | { |
d47cc544 SB |
626 | struct et_node *node = bb->dom[dir]; |
627 | ||
628 | if (!dom_computed[dir]) | |
629 | abort (); | |
630 | ||
631 | if (!node->father) | |
632 | return NULL; | |
633 | ||
634 | return node->father->data; | |
355be0dc JH |
635 | } |
636 | ||
637 | /* Set the immediate dominator of the block possibly removing | |
638 | existing edge. NULL can be used to remove any edge. */ | |
639 | inline void | |
d47cc544 SB |
640 | set_immediate_dominator (enum cdi_direction dir, basic_block bb, |
641 | basic_block dominated_by) | |
355be0dc | 642 | { |
d47cc544 SB |
643 | struct et_node *node = bb->dom[dir]; |
644 | ||
645 | if (!dom_computed[dir]) | |
646 | abort (); | |
355be0dc | 647 | |
d47cc544 | 648 | if (node->father) |
355be0dc | 649 | { |
d47cc544 SB |
650 | if (node->father->data == dominated_by) |
651 | return; | |
652 | et_split (node); | |
355be0dc | 653 | } |
d47cc544 SB |
654 | |
655 | if (dominated_by) | |
656 | et_set_father (node, dominated_by->dom[dir]); | |
657 | ||
658 | if (dom_computed[dir] == DOM_OK) | |
659 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
660 | } |
661 | ||
5d3cc252 | 662 | /* Store all basic blocks immediately dominated by BB into BBS and return |
d47cc544 | 663 | their number. */ |
355be0dc | 664 | int |
d47cc544 | 665 | get_dominated_by (enum cdi_direction dir, basic_block bb, basic_block **bbs) |
355be0dc | 666 | { |
d47cc544 SB |
667 | int n; |
668 | struct et_node *node = bb->dom[dir], *son = node->son, *ason; | |
669 | ||
670 | if (!dom_computed[dir]) | |
671 | abort (); | |
672 | ||
673 | if (!son) | |
674 | { | |
675 | *bbs = NULL; | |
676 | return 0; | |
677 | } | |
678 | ||
679 | for (ason = son->right, n = 1; ason != son; ason = ason->right) | |
680 | n++; | |
681 | ||
682 | *bbs = xmalloc (n * sizeof (basic_block)); | |
683 | (*bbs)[0] = son->data; | |
684 | for (ason = son->right, n = 1; ason != son; ason = ason->right) | |
685 | (*bbs)[n++] = ason->data; | |
355be0dc | 686 | |
355be0dc JH |
687 | return n; |
688 | } | |
689 | ||
690 | /* Redirect all edges pointing to BB to TO. */ | |
691 | void | |
d47cc544 SB |
692 | redirect_immediate_dominators (enum cdi_direction dir, basic_block bb, |
693 | basic_block to) | |
355be0dc | 694 | { |
d47cc544 SB |
695 | struct et_node *bb_node = bb->dom[dir], *to_node = to->dom[dir], *son; |
696 | ||
697 | if (!dom_computed[dir]) | |
698 | abort (); | |
355be0dc | 699 | |
d47cc544 SB |
700 | if (!bb_node->son) |
701 | return; | |
702 | ||
703 | while (bb_node->son) | |
355be0dc | 704 | { |
d47cc544 SB |
705 | son = bb_node->son; |
706 | ||
707 | et_split (son); | |
708 | et_set_father (son, to_node); | |
355be0dc | 709 | } |
d47cc544 SB |
710 | |
711 | if (dom_computed[dir] == DOM_OK) | |
712 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
713 | } |
714 | ||
715 | /* Find first basic block in the tree dominating both BB1 and BB2. */ | |
716 | basic_block | |
d47cc544 | 717 | nearest_common_dominator (enum cdi_direction dir, basic_block bb1, basic_block bb2) |
355be0dc | 718 | { |
d47cc544 SB |
719 | if (!dom_computed[dir]) |
720 | abort (); | |
721 | ||
355be0dc JH |
722 | if (!bb1) |
723 | return bb2; | |
724 | if (!bb2) | |
725 | return bb1; | |
d47cc544 SB |
726 | |
727 | return et_nca (bb1->dom[dir], bb2->dom[dir])->data; | |
355be0dc JH |
728 | } |
729 | ||
730 | /* Return TRUE in case BB1 is dominated by BB2. */ | |
731 | bool | |
d47cc544 | 732 | dominated_by_p (enum cdi_direction dir, basic_block bb1, basic_block bb2) |
355be0dc | 733 | { |
d47cc544 SB |
734 | struct et_node *n1 = bb1->dom[dir], *n2 = bb2->dom[dir]; |
735 | ||
736 | if (!dom_computed[dir]) | |
737 | abort (); | |
738 | ||
739 | if (dom_computed[dir] == DOM_OK) | |
740 | return (n1->dfs_num_in >= n2->dfs_num_in | |
741 | && n1->dfs_num_out <= n2->dfs_num_out); | |
742 | ||
743 | return et_below (n1, n2); | |
355be0dc JH |
744 | } |
745 | ||
746 | /* Verify invariants of dominator structure. */ | |
747 | void | |
d47cc544 | 748 | verify_dominators (enum cdi_direction dir) |
355be0dc JH |
749 | { |
750 | int err = 0; | |
751 | basic_block bb; | |
752 | ||
d47cc544 SB |
753 | if (!dom_computed[dir]) |
754 | abort (); | |
755 | ||
355be0dc JH |
756 | FOR_EACH_BB (bb) |
757 | { | |
758 | basic_block dom_bb; | |
759 | ||
d47cc544 SB |
760 | dom_bb = recount_dominator (dir, bb); |
761 | if (dom_bb != get_immediate_dominator (dir, bb)) | |
f8032688 | 762 | { |
355be0dc | 763 | error ("dominator of %d should be %d, not %d", |
d47cc544 | 764 | bb->index, dom_bb->index, get_immediate_dominator(dir, bb)->index); |
355be0dc JH |
765 | err = 1; |
766 | } | |
767 | } | |
768 | if (err) | |
769 | abort (); | |
770 | } | |
771 | ||
738ed977 ZD |
772 | /* Determine immediate dominator (or postdominator, according to DIR) of BB, |
773 | assuming that dominators of other blocks are correct. We also use it to | |
774 | recompute the dominators in a restricted area, by iterating it until it | |
71cc389b | 775 | reaches a fixed point. */ |
738ed977 | 776 | |
355be0dc | 777 | basic_block |
d47cc544 | 778 | recount_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 779 | { |
738ed977 ZD |
780 | basic_block dom_bb = NULL; |
781 | edge e; | |
355be0dc | 782 | |
d47cc544 SB |
783 | if (!dom_computed[dir]) |
784 | abort (); | |
785 | ||
738ed977 ZD |
786 | if (dir == CDI_DOMINATORS) |
787 | { | |
788 | for (e = bb->pred; e; e = e->pred_next) | |
789 | { | |
790 | if (!dominated_by_p (dir, e->src, bb)) | |
791 | dom_bb = nearest_common_dominator (dir, dom_bb, e->src); | |
792 | } | |
793 | } | |
794 | else | |
795 | { | |
796 | for (e = bb->succ; e; e = e->succ_next) | |
797 | { | |
798 | if (!dominated_by_p (dir, e->dest, bb)) | |
799 | dom_bb = nearest_common_dominator (dir, dom_bb, e->dest); | |
800 | } | |
801 | } | |
f8032688 | 802 | |
738ed977 | 803 | return dom_bb; |
355be0dc JH |
804 | } |
805 | ||
806 | /* Iteratively recount dominators of BBS. The change is supposed to be local | |
807 | and not to grow further. */ | |
808 | void | |
d47cc544 | 809 | iterate_fix_dominators (enum cdi_direction dir, basic_block *bbs, int n) |
355be0dc JH |
810 | { |
811 | int i, changed = 1; | |
812 | basic_block old_dom, new_dom; | |
813 | ||
d47cc544 SB |
814 | if (!dom_computed[dir]) |
815 | abort (); | |
816 | ||
355be0dc JH |
817 | while (changed) |
818 | { | |
819 | changed = 0; | |
820 | for (i = 0; i < n; i++) | |
821 | { | |
d47cc544 SB |
822 | old_dom = get_immediate_dominator (dir, bbs[i]); |
823 | new_dom = recount_dominator (dir, bbs[i]); | |
355be0dc JH |
824 | if (old_dom != new_dom) |
825 | { | |
826 | changed = 1; | |
d47cc544 | 827 | set_immediate_dominator (dir, bbs[i], new_dom); |
355be0dc | 828 | } |
f8032688 MM |
829 | } |
830 | } | |
355be0dc | 831 | } |
f8032688 | 832 | |
355be0dc | 833 | void |
d47cc544 | 834 | add_to_dominance_info (enum cdi_direction dir, basic_block bb) |
355be0dc | 835 | { |
d47cc544 | 836 | if (!dom_computed[dir]) |
355be0dc | 837 | abort (); |
d47cc544 SB |
838 | |
839 | if (bb->dom[dir]) | |
840 | abort (); | |
841 | ||
842 | bb->dom[dir] = et_new_tree (bb); | |
843 | ||
844 | if (dom_computed[dir] == DOM_OK) | |
845 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
846 | } |
847 | ||
848 | void | |
d47cc544 SB |
849 | delete_from_dominance_info (enum cdi_direction dir, basic_block bb) |
850 | { | |
851 | if (!dom_computed[dir]) | |
852 | abort (); | |
853 | ||
854 | et_free_tree (bb->dom[dir]); | |
855 | bb->dom[dir] = NULL; | |
856 | ||
857 | if (dom_computed[dir] == DOM_OK) | |
858 | dom_computed[dir] = DOM_NO_FAST_QUERY; | |
859 | } | |
860 | ||
861 | /* Returns the first son of BB in the dominator or postdominator tree | |
862 | as determined by DIR. */ | |
863 | ||
864 | basic_block | |
865 | first_dom_son (enum cdi_direction dir, basic_block bb) | |
355be0dc | 866 | { |
d47cc544 SB |
867 | struct et_node *son = bb->dom[dir]->son; |
868 | ||
869 | return son ? son->data : NULL; | |
870 | } | |
871 | ||
872 | /* Returns the next dominance son after BB in the dominator or postdominator | |
873 | tree as determined by DIR, or NULL if it was the last one. */ | |
874 | ||
875 | basic_block | |
876 | next_dom_son (enum cdi_direction dir, basic_block bb) | |
877 | { | |
878 | struct et_node *next = bb->dom[dir]->right; | |
879 | ||
880 | return next->father->son == next ? NULL : next->data; | |
355be0dc JH |
881 | } |
882 | ||
883 | void | |
d47cc544 | 884 | debug_dominance_info (enum cdi_direction dir) |
355be0dc JH |
885 | { |
886 | basic_block bb, bb2; | |
887 | FOR_EACH_BB (bb) | |
d47cc544 | 888 | if ((bb2 = get_immediate_dominator (dir, bb))) |
355be0dc | 889 | fprintf (stderr, "%i %i\n", bb->index, bb2->index); |
f8032688 | 890 | } |