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f8032688 | 1 | /* Calculate (post)dominators in slightly super-linear time. |
fa10beec RW |
2 | Copyright (C) 2000, 2003, 2004, 2005, 2006, 2007, 2008 Free |
3 | Software Foundation, Inc. | |
f8032688 | 4 | Contributed by Michael Matz (matz@ifh.de). |
3a538a66 | 5 | |
1322177d | 6 | This file is part of GCC. |
3a538a66 | 7 | |
1322177d LB |
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 | |
9dcd6f09 | 10 | the Free Software Foundation; either version 3, or (at your option) |
f8032688 MM |
11 | any later version. |
12 | ||
1322177d LB |
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. | |
f8032688 MM |
17 | |
18 | You should have received a copy of the GNU General Public License | |
9dcd6f09 NC |
19 | along with GCC; see the file COPYING3. If not see |
20 | <http://www.gnu.org/licenses/>. */ | |
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" |
74c96e0c | 46 | #include "timevar.h" |
66f97d31 ZD |
47 | #include "vecprim.h" |
48 | #include "pointer-set.h" | |
49 | #include "graphds.h" | |
f8032688 | 50 | |
f8032688 MM |
51 | /* We name our nodes with integers, beginning with 1. Zero is reserved for |
52 | 'undefined' or 'end of list'. The name of each node is given by the dfs | |
53 | number of the corresponding basic block. Please note, that we include the | |
54 | artificial ENTRY_BLOCK (or EXIT_BLOCK in the post-dom case) in our lists to | |
24bd1a0b | 55 | support multiple entry points. 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. */ | |
fa10beec | 86 | /* set_chain[x] is the next node on the path from x to the representative |
f8032688 MM |
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 | 116 | static void free_dom_info (struct dom_info *); |
2b28c07a JC |
117 | static void calc_dfs_tree_nonrec (struct dom_info *, basic_block, bool); |
118 | static void calc_dfs_tree (struct dom_info *, bool); | |
7080f735 AJ |
119 | static void compress (struct dom_info *, TBB); |
120 | static TBB eval (struct dom_info *, TBB); | |
121 | static void link_roots (struct dom_info *, TBB, TBB); | |
2b28c07a | 122 | static void calc_idoms (struct dom_info *, bool); |
d47cc544 | 123 | void debug_dominance_info (enum cdi_direction); |
1fc3998d | 124 | void debug_dominance_tree (enum cdi_direction, basic_block); |
f8032688 MM |
125 | |
126 | /* Helper macro for allocating and initializing an array, | |
127 | for aesthetic reasons. */ | |
128 | #define init_ar(var, type, num, content) \ | |
3a538a66 KH |
129 | do \ |
130 | { \ | |
131 | unsigned int i = 1; /* Catch content == i. */ \ | |
132 | if (! (content)) \ | |
5ed6ace5 | 133 | (var) = XCNEWVEC (type, num); \ |
3a538a66 KH |
134 | else \ |
135 | { \ | |
5ed6ace5 | 136 | (var) = XNEWVEC (type, (num)); \ |
3a538a66 KH |
137 | for (i = 0; i < num; i++) \ |
138 | (var)[i] = (content); \ | |
139 | } \ | |
140 | } \ | |
141 | while (0) | |
f8032688 MM |
142 | |
143 | /* Allocate all needed memory in a pessimistic fashion (so we round up). | |
4912a07c | 144 | This initializes the contents of DI, which already must be allocated. */ |
f8032688 MM |
145 | |
146 | static void | |
26e0e410 | 147 | init_dom_info (struct dom_info *di, enum cdi_direction dir) |
f8032688 | 148 | { |
6fb5fa3c | 149 | /* We need memory for n_basic_blocks nodes. */ |
24bd1a0b | 150 | unsigned int num = n_basic_blocks; |
f8032688 MM |
151 | init_ar (di->dfs_parent, TBB, num, 0); |
152 | init_ar (di->path_min, TBB, num, i); | |
153 | init_ar (di->key, TBB, num, i); | |
154 | init_ar (di->dom, TBB, num, 0); | |
155 | ||
156 | init_ar (di->bucket, TBB, num, 0); | |
157 | init_ar (di->next_bucket, TBB, num, 0); | |
158 | ||
159 | init_ar (di->set_chain, TBB, num, 0); | |
160 | init_ar (di->set_size, unsigned int, num, 1); | |
161 | init_ar (di->set_child, TBB, num, 0); | |
162 | ||
d55bc081 | 163 | init_ar (di->dfs_order, TBB, (unsigned int) last_basic_block + 1, 0); |
f8032688 MM |
164 | init_ar (di->dfs_to_bb, basic_block, num, 0); |
165 | ||
166 | di->dfsnum = 1; | |
167 | di->nodes = 0; | |
26e0e410 | 168 | |
2b28c07a JC |
169 | switch (dir) |
170 | { | |
171 | case CDI_DOMINATORS: | |
172 | di->fake_exit_edge = NULL; | |
173 | break; | |
174 | case CDI_POST_DOMINATORS: | |
175 | di->fake_exit_edge = BITMAP_ALLOC (NULL); | |
176 | break; | |
177 | default: | |
178 | gcc_unreachable (); | |
179 | break; | |
180 | } | |
f8032688 MM |
181 | } |
182 | ||
183 | #undef init_ar | |
184 | ||
2b28c07a JC |
185 | /* Map dominance calculation type to array index used for various |
186 | dominance information arrays. This version is simple -- it will need | |
187 | to be modified, obviously, if additional values are added to | |
188 | cdi_direction. */ | |
189 | ||
190 | static unsigned int | |
191 | dom_convert_dir_to_idx (enum cdi_direction dir) | |
192 | { | |
193 | gcc_assert (dir == CDI_DOMINATORS || dir == CDI_POST_DOMINATORS); | |
194 | return dir - 1; | |
195 | } | |
196 | ||
f8032688 MM |
197 | /* Free all allocated memory in DI, but not DI itself. */ |
198 | ||
199 | static void | |
7080f735 | 200 | free_dom_info (struct dom_info *di) |
f8032688 MM |
201 | { |
202 | free (di->dfs_parent); | |
203 | free (di->path_min); | |
204 | free (di->key); | |
205 | free (di->dom); | |
206 | free (di->bucket); | |
207 | free (di->next_bucket); | |
208 | free (di->set_chain); | |
209 | free (di->set_size); | |
210 | free (di->set_child); | |
211 | free (di->dfs_order); | |
212 | free (di->dfs_to_bb); | |
8bdbfff5 | 213 | BITMAP_FREE (di->fake_exit_edge); |
f8032688 MM |
214 | } |
215 | ||
216 | /* The nonrecursive variant of creating a DFS tree. DI is our working | |
217 | structure, BB the starting basic block for this tree and REVERSE | |
218 | is true, if predecessors should be visited instead of successors of a | |
219 | node. After this is done all nodes reachable from BB were visited, have | |
220 | assigned their dfs number and are linked together to form a tree. */ | |
221 | ||
222 | static void | |
2b28c07a | 223 | calc_dfs_tree_nonrec (struct dom_info *di, basic_block bb, bool reverse) |
f8032688 | 224 | { |
f8032688 MM |
225 | /* We call this _only_ if bb is not already visited. */ |
226 | edge e; | |
227 | TBB child_i, my_i = 0; | |
628f6a4e BE |
228 | edge_iterator *stack; |
229 | edge_iterator ei, einext; | |
f8032688 MM |
230 | int sp; |
231 | /* Start block (ENTRY_BLOCK_PTR for forward problem, EXIT_BLOCK for backward | |
232 | problem). */ | |
233 | basic_block en_block; | |
234 | /* Ending block. */ | |
235 | basic_block ex_block; | |
236 | ||
5ed6ace5 | 237 | stack = XNEWVEC (edge_iterator, n_basic_blocks + 1); |
f8032688 MM |
238 | sp = 0; |
239 | ||
240 | /* Initialize our border blocks, and the first edge. */ | |
241 | if (reverse) | |
242 | { | |
628f6a4e | 243 | ei = ei_start (bb->preds); |
f8032688 MM |
244 | en_block = EXIT_BLOCK_PTR; |
245 | ex_block = ENTRY_BLOCK_PTR; | |
246 | } | |
247 | else | |
248 | { | |
628f6a4e | 249 | ei = ei_start (bb->succs); |
f8032688 MM |
250 | en_block = ENTRY_BLOCK_PTR; |
251 | ex_block = EXIT_BLOCK_PTR; | |
252 | } | |
253 | ||
254 | /* When the stack is empty we break out of this loop. */ | |
255 | while (1) | |
256 | { | |
257 | basic_block bn; | |
258 | ||
259 | /* This loop traverses edges e in depth first manner, and fills the | |
260 | stack. */ | |
628f6a4e | 261 | while (!ei_end_p (ei)) |
f8032688 | 262 | { |
628f6a4e | 263 | e = ei_edge (ei); |
f8032688 MM |
264 | |
265 | /* Deduce from E the current and the next block (BB and BN), and the | |
266 | next edge. */ | |
267 | if (reverse) | |
268 | { | |
269 | bn = e->src; | |
270 | ||
271 | /* If the next node BN is either already visited or a border | |
272 | block the current edge is useless, and simply overwritten | |
273 | with the next edge out of the current node. */ | |
0b17ab2f | 274 | if (bn == ex_block || di->dfs_order[bn->index]) |
f8032688 | 275 | { |
628f6a4e | 276 | ei_next (&ei); |
f8032688 MM |
277 | continue; |
278 | } | |
279 | bb = e->dest; | |
628f6a4e | 280 | einext = ei_start (bn->preds); |
f8032688 MM |
281 | } |
282 | else | |
283 | { | |
284 | bn = e->dest; | |
0b17ab2f | 285 | if (bn == ex_block || di->dfs_order[bn->index]) |
f8032688 | 286 | { |
628f6a4e | 287 | ei_next (&ei); |
f8032688 MM |
288 | continue; |
289 | } | |
290 | bb = e->src; | |
628f6a4e | 291 | einext = ei_start (bn->succs); |
f8032688 MM |
292 | } |
293 | ||
ced3f397 | 294 | gcc_assert (bn != en_block); |
f8032688 MM |
295 | |
296 | /* Fill the DFS tree info calculatable _before_ recursing. */ | |
297 | if (bb != en_block) | |
0b17ab2f | 298 | my_i = di->dfs_order[bb->index]; |
f8032688 | 299 | else |
d55bc081 | 300 | my_i = di->dfs_order[last_basic_block]; |
0b17ab2f | 301 | child_i = di->dfs_order[bn->index] = di->dfsnum++; |
f8032688 MM |
302 | di->dfs_to_bb[child_i] = bn; |
303 | di->dfs_parent[child_i] = my_i; | |
304 | ||
305 | /* Save the current point in the CFG on the stack, and recurse. */ | |
628f6a4e BE |
306 | stack[sp++] = ei; |
307 | ei = einext; | |
f8032688 MM |
308 | } |
309 | ||
310 | if (!sp) | |
311 | break; | |
628f6a4e | 312 | ei = stack[--sp]; |
f8032688 MM |
313 | |
314 | /* OK. The edge-list was exhausted, meaning normally we would | |
315 | end the recursion. After returning from the recursive call, | |
316 | there were (may be) other statements which were run after a | |
317 | child node was completely considered by DFS. Here is the | |
318 | point to do it in the non-recursive variant. | |
319 | E.g. The block just completed is in e->dest for forward DFS, | |
320 | the block not yet completed (the parent of the one above) | |
321 | in e->src. This could be used e.g. for computing the number of | |
322 | descendants or the tree depth. */ | |
628f6a4e | 323 | ei_next (&ei); |
f8032688 MM |
324 | } |
325 | free (stack); | |
326 | } | |
327 | ||
328 | /* The main entry for calculating the DFS tree or forest. DI is our working | |
329 | structure and REVERSE is true, if we are interested in the reverse flow | |
330 | graph. In that case the result is not necessarily a tree but a forest, | |
331 | because there may be nodes from which the EXIT_BLOCK is unreachable. */ | |
332 | ||
333 | static void | |
2b28c07a | 334 | calc_dfs_tree (struct dom_info *di, bool reverse) |
f8032688 MM |
335 | { |
336 | /* The first block is the ENTRY_BLOCK (or EXIT_BLOCK if REVERSE). */ | |
337 | basic_block begin = reverse ? EXIT_BLOCK_PTR : ENTRY_BLOCK_PTR; | |
d55bc081 | 338 | di->dfs_order[last_basic_block] = di->dfsnum; |
f8032688 MM |
339 | di->dfs_to_bb[di->dfsnum] = begin; |
340 | di->dfsnum++; | |
341 | ||
342 | calc_dfs_tree_nonrec (di, begin, reverse); | |
343 | ||
344 | if (reverse) | |
345 | { | |
346 | /* In the post-dom case we may have nodes without a path to EXIT_BLOCK. | |
347 | They are reverse-unreachable. In the dom-case we disallow such | |
26e0e410 RH |
348 | nodes, but in post-dom we have to deal with them. |
349 | ||
350 | There are two situations in which this occurs. First, noreturn | |
351 | functions. Second, infinite loops. In the first case we need to | |
352 | pretend that there is an edge to the exit block. In the second | |
353 | case, we wind up with a forest. We need to process all noreturn | |
354 | blocks before we know if we've got any infinite loops. */ | |
355 | ||
e0082a72 | 356 | basic_block b; |
26e0e410 RH |
357 | bool saw_unconnected = false; |
358 | ||
e0082a72 | 359 | FOR_EACH_BB_REVERSE (b) |
f8032688 | 360 | { |
628f6a4e | 361 | if (EDGE_COUNT (b->succs) > 0) |
26e0e410 RH |
362 | { |
363 | if (di->dfs_order[b->index] == 0) | |
364 | saw_unconnected = true; | |
365 | continue; | |
366 | } | |
367 | bitmap_set_bit (di->fake_exit_edge, b->index); | |
0b17ab2f | 368 | di->dfs_order[b->index] = di->dfsnum; |
f8032688 | 369 | di->dfs_to_bb[di->dfsnum] = b; |
26e0e410 | 370 | di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block]; |
f8032688 MM |
371 | di->dfsnum++; |
372 | calc_dfs_tree_nonrec (di, b, reverse); | |
373 | } | |
26e0e410 RH |
374 | |
375 | if (saw_unconnected) | |
376 | { | |
377 | FOR_EACH_BB_REVERSE (b) | |
378 | { | |
379 | if (di->dfs_order[b->index]) | |
380 | continue; | |
381 | bitmap_set_bit (di->fake_exit_edge, b->index); | |
382 | di->dfs_order[b->index] = di->dfsnum; | |
383 | di->dfs_to_bb[di->dfsnum] = b; | |
384 | di->dfs_parent[di->dfsnum] = di->dfs_order[last_basic_block]; | |
385 | di->dfsnum++; | |
386 | calc_dfs_tree_nonrec (di, b, reverse); | |
387 | } | |
388 | } | |
f8032688 MM |
389 | } |
390 | ||
391 | di->nodes = di->dfsnum - 1; | |
392 | ||
24bd1a0b DB |
393 | /* This aborts e.g. when there is _no_ path from ENTRY to EXIT at all. */ |
394 | gcc_assert (di->nodes == (unsigned int) n_basic_blocks - 1); | |
f8032688 MM |
395 | } |
396 | ||
397 | /* Compress the path from V to the root of its set and update path_min at the | |
398 | same time. After compress(di, V) set_chain[V] is the root of the set V is | |
399 | in and path_min[V] is the node with the smallest key[] value on the path | |
400 | from V to that root. */ | |
401 | ||
402 | static void | |
7080f735 | 403 | compress (struct dom_info *di, TBB v) |
f8032688 MM |
404 | { |
405 | /* Btw. It's not worth to unrecurse compress() as the depth is usually not | |
406 | greater than 5 even for huge graphs (I've not seen call depth > 4). | |
407 | Also performance wise compress() ranges _far_ behind eval(). */ | |
408 | TBB parent = di->set_chain[v]; | |
409 | if (di->set_chain[parent]) | |
410 | { | |
411 | compress (di, parent); | |
412 | if (di->key[di->path_min[parent]] < di->key[di->path_min[v]]) | |
413 | di->path_min[v] = di->path_min[parent]; | |
414 | di->set_chain[v] = di->set_chain[parent]; | |
415 | } | |
416 | } | |
417 | ||
418 | /* Compress the path from V to the set root of V if needed (when the root has | |
419 | changed since the last call). Returns the node with the smallest key[] | |
420 | value on the path from V to the root. */ | |
421 | ||
422 | static inline TBB | |
7080f735 | 423 | eval (struct dom_info *di, TBB v) |
f8032688 | 424 | { |
fa10beec | 425 | /* The representative of the set V is in, also called root (as the set |
f8032688 MM |
426 | representation is a tree). */ |
427 | TBB rep = di->set_chain[v]; | |
428 | ||
429 | /* V itself is the root. */ | |
430 | if (!rep) | |
431 | return di->path_min[v]; | |
432 | ||
433 | /* Compress only if necessary. */ | |
434 | if (di->set_chain[rep]) | |
435 | { | |
436 | compress (di, v); | |
437 | rep = di->set_chain[v]; | |
438 | } | |
439 | ||
440 | if (di->key[di->path_min[rep]] >= di->key[di->path_min[v]]) | |
441 | return di->path_min[v]; | |
442 | else | |
443 | return di->path_min[rep]; | |
444 | } | |
445 | ||
446 | /* This essentially merges the two sets of V and W, giving a single set with | |
447 | the new root V. The internal representation of these disjoint sets is a | |
448 | balanced tree. Currently link(V,W) is only used with V being the parent | |
449 | of W. */ | |
450 | ||
451 | static void | |
7080f735 | 452 | link_roots (struct dom_info *di, TBB v, TBB w) |
f8032688 MM |
453 | { |
454 | TBB s = w; | |
455 | ||
456 | /* Rebalance the tree. */ | |
457 | while (di->key[di->path_min[w]] < di->key[di->path_min[di->set_child[s]]]) | |
458 | { | |
459 | if (di->set_size[s] + di->set_size[di->set_child[di->set_child[s]]] | |
460 | >= 2 * di->set_size[di->set_child[s]]) | |
461 | { | |
462 | di->set_chain[di->set_child[s]] = s; | |
463 | di->set_child[s] = di->set_child[di->set_child[s]]; | |
464 | } | |
465 | else | |
466 | { | |
467 | di->set_size[di->set_child[s]] = di->set_size[s]; | |
468 | s = di->set_chain[s] = di->set_child[s]; | |
469 | } | |
470 | } | |
471 | ||
472 | di->path_min[s] = di->path_min[w]; | |
473 | di->set_size[v] += di->set_size[w]; | |
474 | if (di->set_size[v] < 2 * di->set_size[w]) | |
475 | { | |
476 | TBB tmp = s; | |
477 | s = di->set_child[v]; | |
478 | di->set_child[v] = tmp; | |
479 | } | |
480 | ||
481 | /* Merge all subtrees. */ | |
482 | while (s) | |
483 | { | |
484 | di->set_chain[s] = v; | |
485 | s = di->set_child[s]; | |
486 | } | |
487 | } | |
488 | ||
489 | /* This calculates the immediate dominators (or post-dominators if REVERSE is | |
490 | true). DI is our working structure and should hold the DFS forest. | |
491 | On return the immediate dominator to node V is in di->dom[V]. */ | |
492 | ||
493 | static void | |
2b28c07a | 494 | calc_idoms (struct dom_info *di, bool reverse) |
f8032688 MM |
495 | { |
496 | TBB v, w, k, par; | |
497 | basic_block en_block; | |
628f6a4e BE |
498 | edge_iterator ei, einext; |
499 | ||
f8032688 MM |
500 | if (reverse) |
501 | en_block = EXIT_BLOCK_PTR; | |
502 | else | |
503 | en_block = ENTRY_BLOCK_PTR; | |
504 | ||
505 | /* Go backwards in DFS order, to first look at the leafs. */ | |
506 | v = di->nodes; | |
507 | while (v > 1) | |
508 | { | |
509 | basic_block bb = di->dfs_to_bb[v]; | |
628f6a4e | 510 | edge e; |
f8032688 MM |
511 | |
512 | par = di->dfs_parent[v]; | |
513 | k = v; | |
628f6a4e BE |
514 | |
515 | ei = (reverse) ? ei_start (bb->succs) : ei_start (bb->preds); | |
516 | ||
f8032688 | 517 | if (reverse) |
26e0e410 | 518 | { |
26e0e410 RH |
519 | /* If this block has a fake edge to exit, process that first. */ |
520 | if (bitmap_bit_p (di->fake_exit_edge, bb->index)) | |
521 | { | |
628f6a4e BE |
522 | einext = ei; |
523 | einext.index = 0; | |
26e0e410 RH |
524 | goto do_fake_exit_edge; |
525 | } | |
526 | } | |
f8032688 MM |
527 | |
528 | /* Search all direct predecessors for the smallest node with a path | |
529 | to them. That way we have the smallest node with also a path to | |
530 | us only over nodes behind us. In effect we search for our | |
531 | semidominator. */ | |
628f6a4e | 532 | while (!ei_end_p (ei)) |
f8032688 MM |
533 | { |
534 | TBB k1; | |
535 | basic_block b; | |
536 | ||
628f6a4e BE |
537 | e = ei_edge (ei); |
538 | b = (reverse) ? e->dest : e->src; | |
539 | einext = ei; | |
540 | ei_next (&einext); | |
541 | ||
f8032688 | 542 | if (b == en_block) |
26e0e410 RH |
543 | { |
544 | do_fake_exit_edge: | |
545 | k1 = di->dfs_order[last_basic_block]; | |
546 | } | |
f8032688 | 547 | else |
0b17ab2f | 548 | k1 = di->dfs_order[b->index]; |
f8032688 MM |
549 | |
550 | /* Call eval() only if really needed. If k1 is above V in DFS tree, | |
551 | then we know, that eval(k1) == k1 and key[k1] == k1. */ | |
552 | if (k1 > v) | |
553 | k1 = di->key[eval (di, k1)]; | |
554 | if (k1 < k) | |
555 | k = k1; | |
628f6a4e BE |
556 | |
557 | ei = einext; | |
f8032688 MM |
558 | } |
559 | ||
560 | di->key[v] = k; | |
561 | link_roots (di, par, v); | |
562 | di->next_bucket[v] = di->bucket[k]; | |
563 | di->bucket[k] = v; | |
564 | ||
565 | /* Transform semidominators into dominators. */ | |
566 | for (w = di->bucket[par]; w; w = di->next_bucket[w]) | |
567 | { | |
568 | k = eval (di, w); | |
569 | if (di->key[k] < di->key[w]) | |
570 | di->dom[w] = k; | |
571 | else | |
572 | di->dom[w] = par; | |
573 | } | |
574 | /* We don't need to cleanup next_bucket[]. */ | |
575 | di->bucket[par] = 0; | |
576 | v--; | |
577 | } | |
578 | ||
a1f300c0 | 579 | /* Explicitly define the dominators. */ |
f8032688 MM |
580 | di->dom[1] = 0; |
581 | for (v = 2; v <= di->nodes; v++) | |
582 | if (di->dom[v] != di->key[v]) | |
583 | di->dom[v] = di->dom[di->dom[v]]; | |
584 | } | |
585 | ||
d47cc544 SB |
586 | /* Assign dfs numbers starting from NUM to NODE and its sons. */ |
587 | ||
588 | static void | |
589 | assign_dfs_numbers (struct et_node *node, int *num) | |
590 | { | |
591 | struct et_node *son; | |
592 | ||
593 | node->dfs_num_in = (*num)++; | |
594 | ||
595 | if (node->son) | |
596 | { | |
597 | assign_dfs_numbers (node->son, num); | |
598 | for (son = node->son->right; son != node->son; son = son->right) | |
6de9cd9a | 599 | assign_dfs_numbers (son, num); |
d47cc544 | 600 | } |
f8032688 | 601 | |
d47cc544 SB |
602 | node->dfs_num_out = (*num)++; |
603 | } | |
f8032688 | 604 | |
5d3cc252 | 605 | /* Compute the data necessary for fast resolving of dominator queries in a |
d47cc544 | 606 | static dominator tree. */ |
f8032688 | 607 | |
d47cc544 SB |
608 | static void |
609 | compute_dom_fast_query (enum cdi_direction dir) | |
610 | { | |
611 | int num = 0; | |
612 | basic_block bb; | |
2b28c07a | 613 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
d47cc544 | 614 | |
fce22de5 | 615 | gcc_assert (dom_info_available_p (dir)); |
d47cc544 | 616 | |
2b28c07a | 617 | if (dom_computed[dir_index] == DOM_OK) |
d47cc544 SB |
618 | return; |
619 | ||
620 | FOR_ALL_BB (bb) | |
621 | { | |
2b28c07a JC |
622 | if (!bb->dom[dir_index]->father) |
623 | assign_dfs_numbers (bb->dom[dir_index], &num); | |
d47cc544 SB |
624 | } |
625 | ||
2b28c07a | 626 | dom_computed[dir_index] = DOM_OK; |
d47cc544 SB |
627 | } |
628 | ||
629 | /* The main entry point into this module. DIR is set depending on whether | |
630 | we want to compute dominators or postdominators. */ | |
631 | ||
632 | void | |
633 | calculate_dominance_info (enum cdi_direction dir) | |
f8032688 MM |
634 | { |
635 | struct dom_info di; | |
355be0dc | 636 | basic_block b; |
2b28c07a JC |
637 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
638 | bool reverse = (dir == CDI_POST_DOMINATORS) ? true : false; | |
355be0dc | 639 | |
2b28c07a | 640 | if (dom_computed[dir_index] == DOM_OK) |
d47cc544 | 641 | return; |
355be0dc | 642 | |
74c96e0c | 643 | timevar_push (TV_DOMINANCE); |
fce22de5 | 644 | if (!dom_info_available_p (dir)) |
d47cc544 | 645 | { |
2b28c07a | 646 | gcc_assert (!n_bbs_in_dom_tree[dir_index]); |
f8032688 | 647 | |
d47cc544 SB |
648 | FOR_ALL_BB (b) |
649 | { | |
2b28c07a | 650 | b->dom[dir_index] = et_new_tree (b); |
d47cc544 | 651 | } |
2b28c07a | 652 | n_bbs_in_dom_tree[dir_index] = n_basic_blocks; |
f8032688 | 653 | |
26e0e410 | 654 | init_dom_info (&di, dir); |
2b28c07a JC |
655 | calc_dfs_tree (&di, reverse); |
656 | calc_idoms (&di, reverse); | |
355be0dc | 657 | |
d47cc544 SB |
658 | FOR_EACH_BB (b) |
659 | { | |
660 | TBB d = di.dom[di.dfs_order[b->index]]; | |
661 | ||
662 | if (di.dfs_to_bb[d]) | |
2b28c07a | 663 | et_set_father (b->dom[dir_index], di.dfs_to_bb[d]->dom[dir_index]); |
d47cc544 | 664 | } |
e0082a72 | 665 | |
d47cc544 | 666 | free_dom_info (&di); |
2b28c07a | 667 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; |
355be0dc JH |
668 | } |
669 | ||
d47cc544 | 670 | compute_dom_fast_query (dir); |
74c96e0c ZD |
671 | |
672 | timevar_pop (TV_DOMINANCE); | |
355be0dc JH |
673 | } |
674 | ||
d47cc544 | 675 | /* Free dominance information for direction DIR. */ |
355be0dc | 676 | void |
d47cc544 | 677 | free_dominance_info (enum cdi_direction dir) |
355be0dc JH |
678 | { |
679 | basic_block bb; | |
2b28c07a | 680 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
355be0dc | 681 | |
fce22de5 | 682 | if (!dom_info_available_p (dir)) |
d47cc544 SB |
683 | return; |
684 | ||
685 | FOR_ALL_BB (bb) | |
686 | { | |
2b28c07a JC |
687 | et_free_tree_force (bb->dom[dir_index]); |
688 | bb->dom[dir_index] = NULL; | |
d47cc544 | 689 | } |
5a6ccafd | 690 | et_free_pools (); |
d47cc544 | 691 | |
2b28c07a | 692 | n_bbs_in_dom_tree[dir_index] = 0; |
6de9cd9a | 693 | |
2b28c07a | 694 | dom_computed[dir_index] = DOM_NONE; |
355be0dc JH |
695 | } |
696 | ||
697 | /* Return the immediate dominator of basic block BB. */ | |
698 | basic_block | |
d47cc544 | 699 | get_immediate_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 700 | { |
2b28c07a JC |
701 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
702 | struct et_node *node = bb->dom[dir_index]; | |
d47cc544 | 703 | |
2b28c07a | 704 | gcc_assert (dom_computed[dir_index]); |
d47cc544 SB |
705 | |
706 | if (!node->father) | |
707 | return NULL; | |
708 | ||
f883e0a7 | 709 | return (basic_block) node->father->data; |
355be0dc JH |
710 | } |
711 | ||
712 | /* Set the immediate dominator of the block possibly removing | |
713 | existing edge. NULL can be used to remove any edge. */ | |
714 | inline void | |
d47cc544 SB |
715 | set_immediate_dominator (enum cdi_direction dir, basic_block bb, |
716 | basic_block dominated_by) | |
355be0dc | 717 | { |
2b28c07a JC |
718 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
719 | struct et_node *node = bb->dom[dir_index]; | |
b8698a0f | 720 | |
2b28c07a | 721 | gcc_assert (dom_computed[dir_index]); |
355be0dc | 722 | |
d47cc544 | 723 | if (node->father) |
355be0dc | 724 | { |
d47cc544 | 725 | if (node->father->data == dominated_by) |
6de9cd9a | 726 | return; |
d47cc544 | 727 | et_split (node); |
355be0dc | 728 | } |
d47cc544 SB |
729 | |
730 | if (dominated_by) | |
2b28c07a | 731 | et_set_father (node, dominated_by->dom[dir_index]); |
d47cc544 | 732 | |
2b28c07a JC |
733 | if (dom_computed[dir_index] == DOM_OK) |
734 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
735 | } |
736 | ||
66f97d31 ZD |
737 | /* Returns the list of basic blocks immediately dominated by BB, in the |
738 | direction DIR. */ | |
739 | VEC (basic_block, heap) * | |
740 | get_dominated_by (enum cdi_direction dir, basic_block bb) | |
355be0dc | 741 | { |
66f97d31 | 742 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
2b28c07a | 743 | struct et_node *node = bb->dom[dir_index], *son = node->son, *ason; |
66f97d31 ZD |
744 | VEC (basic_block, heap) *bbs = NULL; |
745 | ||
2b28c07a | 746 | gcc_assert (dom_computed[dir_index]); |
d47cc544 SB |
747 | |
748 | if (!son) | |
66f97d31 | 749 | return NULL; |
d47cc544 | 750 | |
f883e0a7 | 751 | VEC_safe_push (basic_block, heap, bbs, (basic_block) son->data); |
2d888286 | 752 | for (ason = son->right; ason != son; ason = ason->right) |
f883e0a7 | 753 | VEC_safe_push (basic_block, heap, bbs, (basic_block) ason->data); |
355be0dc | 754 | |
66f97d31 | 755 | return bbs; |
355be0dc JH |
756 | } |
757 | ||
66f97d31 ZD |
758 | /* Returns the list of basic blocks that are immediately dominated (in |
759 | direction DIR) by some block between N_REGION ones stored in REGION, | |
760 | except for blocks in the REGION itself. */ | |
b8698a0f | 761 | |
66f97d31 | 762 | VEC (basic_block, heap) * |
42759f1e | 763 | get_dominated_by_region (enum cdi_direction dir, basic_block *region, |
66f97d31 | 764 | unsigned n_region) |
42759f1e | 765 | { |
66f97d31 | 766 | unsigned i; |
42759f1e | 767 | basic_block dom; |
66f97d31 | 768 | VEC (basic_block, heap) *doms = NULL; |
42759f1e ZD |
769 | |
770 | for (i = 0; i < n_region; i++) | |
6580ee77 | 771 | region[i]->flags |= BB_DUPLICATED; |
42759f1e ZD |
772 | for (i = 0; i < n_region; i++) |
773 | for (dom = first_dom_son (dir, region[i]); | |
774 | dom; | |
775 | dom = next_dom_son (dir, dom)) | |
6580ee77 | 776 | if (!(dom->flags & BB_DUPLICATED)) |
66f97d31 | 777 | VEC_safe_push (basic_block, heap, doms, dom); |
42759f1e | 778 | for (i = 0; i < n_region; i++) |
6580ee77 | 779 | region[i]->flags &= ~BB_DUPLICATED; |
42759f1e | 780 | |
66f97d31 | 781 | return doms; |
42759f1e ZD |
782 | } |
783 | ||
438c239d RG |
784 | /* Returns the list of basic blocks including BB dominated by BB, in the |
785 | direction DIR. The vector will be sorted in preorder. */ | |
786 | ||
787 | VEC (basic_block, heap) * | |
788 | get_all_dominated_blocks (enum cdi_direction dir, basic_block bb) | |
789 | { | |
790 | VEC(basic_block, heap) *bbs = NULL; | |
791 | unsigned i; | |
792 | ||
793 | i = 0; | |
794 | VEC_safe_push (basic_block, heap, bbs, bb); | |
795 | ||
796 | do | |
797 | { | |
798 | basic_block son; | |
799 | ||
800 | bb = VEC_index (basic_block, bbs, i++); | |
801 | for (son = first_dom_son (dir, bb); | |
802 | son; | |
803 | son = next_dom_son (dir, son)) | |
804 | VEC_safe_push (basic_block, heap, bbs, son); | |
805 | } | |
806 | while (i < VEC_length (basic_block, bbs)); | |
807 | ||
808 | return bbs; | |
809 | } | |
810 | ||
355be0dc JH |
811 | /* Redirect all edges pointing to BB to TO. */ |
812 | void | |
d47cc544 SB |
813 | redirect_immediate_dominators (enum cdi_direction dir, basic_block bb, |
814 | basic_block to) | |
355be0dc | 815 | { |
2b28c07a JC |
816 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
817 | struct et_node *bb_node, *to_node, *son; | |
b8698a0f | 818 | |
2b28c07a JC |
819 | bb_node = bb->dom[dir_index]; |
820 | to_node = to->dom[dir_index]; | |
d47cc544 | 821 | |
2b28c07a | 822 | gcc_assert (dom_computed[dir_index]); |
355be0dc | 823 | |
d47cc544 SB |
824 | if (!bb_node->son) |
825 | return; | |
826 | ||
827 | while (bb_node->son) | |
355be0dc | 828 | { |
d47cc544 SB |
829 | son = bb_node->son; |
830 | ||
831 | et_split (son); | |
832 | et_set_father (son, to_node); | |
355be0dc | 833 | } |
d47cc544 | 834 | |
2b28c07a JC |
835 | if (dom_computed[dir_index] == DOM_OK) |
836 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
837 | } |
838 | ||
839 | /* Find first basic block in the tree dominating both BB1 and BB2. */ | |
840 | basic_block | |
d47cc544 | 841 | nearest_common_dominator (enum cdi_direction dir, basic_block bb1, basic_block bb2) |
355be0dc | 842 | { |
2b28c07a JC |
843 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
844 | ||
845 | gcc_assert (dom_computed[dir_index]); | |
d47cc544 | 846 | |
355be0dc JH |
847 | if (!bb1) |
848 | return bb2; | |
849 | if (!bb2) | |
850 | return bb1; | |
d47cc544 | 851 | |
f883e0a7 | 852 | return (basic_block) et_nca (bb1->dom[dir_index], bb2->dom[dir_index])->data; |
355be0dc JH |
853 | } |
854 | ||
0bca51f0 DN |
855 | |
856 | /* Find the nearest common dominator for the basic blocks in BLOCKS, | |
857 | using dominance direction DIR. */ | |
858 | ||
859 | basic_block | |
860 | nearest_common_dominator_for_set (enum cdi_direction dir, bitmap blocks) | |
861 | { | |
862 | unsigned i, first; | |
863 | bitmap_iterator bi; | |
864 | basic_block dom; | |
b8698a0f | 865 | |
0bca51f0 DN |
866 | first = bitmap_first_set_bit (blocks); |
867 | dom = BASIC_BLOCK (first); | |
868 | EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi) | |
869 | if (dom != BASIC_BLOCK (i)) | |
870 | dom = nearest_common_dominator (dir, dom, BASIC_BLOCK (i)); | |
871 | ||
872 | return dom; | |
873 | } | |
874 | ||
b629276a DB |
875 | /* Given a dominator tree, we can determine whether one thing |
876 | dominates another in constant time by using two DFS numbers: | |
877 | ||
878 | 1. The number for when we visit a node on the way down the tree | |
879 | 2. The number for when we visit a node on the way back up the tree | |
880 | ||
881 | You can view these as bounds for the range of dfs numbers the | |
882 | nodes in the subtree of the dominator tree rooted at that node | |
883 | will contain. | |
b8698a0f | 884 | |
b629276a DB |
885 | The dominator tree is always a simple acyclic tree, so there are |
886 | only three possible relations two nodes in the dominator tree have | |
887 | to each other: | |
b8698a0f | 888 | |
b629276a DB |
889 | 1. Node A is above Node B (and thus, Node A dominates node B) |
890 | ||
891 | A | |
892 | | | |
893 | C | |
894 | / \ | |
895 | B D | |
896 | ||
897 | ||
898 | In the above case, DFS_Number_In of A will be <= DFS_Number_In of | |
899 | B, and DFS_Number_Out of A will be >= DFS_Number_Out of B. This is | |
900 | because we must hit A in the dominator tree *before* B on the walk | |
901 | down, and we will hit A *after* B on the walk back up | |
b8698a0f | 902 | |
d8701f02 | 903 | 2. Node A is below node B (and thus, node B dominates node A) |
b8698a0f L |
904 | |
905 | ||
b629276a DB |
906 | B |
907 | | | |
908 | A | |
909 | / \ | |
910 | C D | |
911 | ||
912 | In the above case, DFS_Number_In of A will be >= DFS_Number_In of | |
913 | B, and DFS_Number_Out of A will be <= DFS_Number_Out of B. | |
b8698a0f | 914 | |
b629276a DB |
915 | This is because we must hit A in the dominator tree *after* B on |
916 | the walk down, and we will hit A *before* B on the walk back up | |
b8698a0f | 917 | |
b629276a DB |
918 | 3. Node A and B are siblings (and thus, neither dominates the other) |
919 | ||
920 | C | |
921 | | | |
922 | D | |
923 | / \ | |
924 | A B | |
925 | ||
926 | In the above case, DFS_Number_In of A will *always* be <= | |
927 | DFS_Number_In of B, and DFS_Number_Out of A will *always* be <= | |
928 | DFS_Number_Out of B. This is because we will always finish the dfs | |
929 | walk of one of the subtrees before the other, and thus, the dfs | |
930 | numbers for one subtree can't intersect with the range of dfs | |
931 | numbers for the other subtree. If you swap A and B's position in | |
932 | the dominator tree, the comparison changes direction, but the point | |
933 | is that both comparisons will always go the same way if there is no | |
934 | dominance relationship. | |
935 | ||
936 | Thus, it is sufficient to write | |
937 | ||
938 | A_Dominates_B (node A, node B) | |
939 | { | |
b8698a0f | 940 | return DFS_Number_In(A) <= DFS_Number_In(B) |
b629276a DB |
941 | && DFS_Number_Out (A) >= DFS_Number_Out(B); |
942 | } | |
943 | ||
944 | A_Dominated_by_B (node A, node B) | |
945 | { | |
946 | return DFS_Number_In(A) >= DFS_Number_In(A) | |
947 | && DFS_Number_Out (A) <= DFS_Number_Out(B); | |
948 | } */ | |
0bca51f0 | 949 | |
355be0dc JH |
950 | /* Return TRUE in case BB1 is dominated by BB2. */ |
951 | bool | |
ed7a4b4b | 952 | dominated_by_p (enum cdi_direction dir, const_basic_block bb1, const_basic_block bb2) |
b8698a0f | 953 | { |
2b28c07a JC |
954 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
955 | struct et_node *n1 = bb1->dom[dir_index], *n2 = bb2->dom[dir_index]; | |
b8698a0f | 956 | |
2b28c07a | 957 | gcc_assert (dom_computed[dir_index]); |
d47cc544 | 958 | |
2b28c07a | 959 | if (dom_computed[dir_index] == DOM_OK) |
d47cc544 | 960 | return (n1->dfs_num_in >= n2->dfs_num_in |
6de9cd9a | 961 | && n1->dfs_num_out <= n2->dfs_num_out); |
d47cc544 SB |
962 | |
963 | return et_below (n1, n2); | |
355be0dc JH |
964 | } |
965 | ||
f074ff6c ZD |
966 | /* Returns the entry dfs number for basic block BB, in the direction DIR. */ |
967 | ||
968 | unsigned | |
969 | bb_dom_dfs_in (enum cdi_direction dir, basic_block bb) | |
970 | { | |
2b28c07a JC |
971 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
972 | struct et_node *n = bb->dom[dir_index]; | |
f074ff6c | 973 | |
2b28c07a | 974 | gcc_assert (dom_computed[dir_index] == DOM_OK); |
f074ff6c ZD |
975 | return n->dfs_num_in; |
976 | } | |
977 | ||
978 | /* Returns the exit dfs number for basic block BB, in the direction DIR. */ | |
979 | ||
980 | unsigned | |
981 | bb_dom_dfs_out (enum cdi_direction dir, basic_block bb) | |
982 | { | |
2b28c07a JC |
983 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
984 | struct et_node *n = bb->dom[dir_index]; | |
f074ff6c | 985 | |
2b28c07a | 986 | gcc_assert (dom_computed[dir_index] == DOM_OK); |
f074ff6c ZD |
987 | return n->dfs_num_out; |
988 | } | |
989 | ||
355be0dc JH |
990 | /* Verify invariants of dominator structure. */ |
991 | void | |
d47cc544 | 992 | verify_dominators (enum cdi_direction dir) |
355be0dc JH |
993 | { |
994 | int err = 0; | |
1fc3998d ZD |
995 | basic_block bb, imm_bb, imm_bb_correct; |
996 | struct dom_info di; | |
997 | bool reverse = (dir == CDI_POST_DOMINATORS) ? true : false; | |
355be0dc | 998 | |
fce22de5 | 999 | gcc_assert (dom_info_available_p (dir)); |
d47cc544 | 1000 | |
1fc3998d ZD |
1001 | init_dom_info (&di, dir); |
1002 | calc_dfs_tree (&di, reverse); | |
1003 | calc_idoms (&di, reverse); | |
1004 | ||
355be0dc JH |
1005 | FOR_EACH_BB (bb) |
1006 | { | |
1fc3998d ZD |
1007 | imm_bb = get_immediate_dominator (dir, bb); |
1008 | if (!imm_bb) | |
f8032688 | 1009 | { |
66f97d31 | 1010 | error ("dominator of %d status unknown", bb->index); |
355be0dc JH |
1011 | err = 1; |
1012 | } | |
66f97d31 | 1013 | |
1fc3998d ZD |
1014 | imm_bb_correct = di.dfs_to_bb[di.dom[di.dfs_order[bb->index]]]; |
1015 | if (imm_bb != imm_bb_correct) | |
e7bd94cc | 1016 | { |
66f97d31 | 1017 | error ("dominator of %d should be %d, not %d", |
1fc3998d | 1018 | bb->index, imm_bb_correct->index, imm_bb->index); |
66f97d31 | 1019 | err = 1; |
e7bd94cc ZD |
1020 | } |
1021 | } | |
1022 | ||
1fc3998d | 1023 | free_dom_info (&di); |
ced3f397 | 1024 | gcc_assert (!err); |
355be0dc JH |
1025 | } |
1026 | ||
738ed977 ZD |
1027 | /* Determine immediate dominator (or postdominator, according to DIR) of BB, |
1028 | assuming that dominators of other blocks are correct. We also use it to | |
1029 | recompute the dominators in a restricted area, by iterating it until it | |
71cc389b | 1030 | reaches a fixed point. */ |
738ed977 | 1031 | |
355be0dc | 1032 | basic_block |
66f97d31 | 1033 | recompute_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 1034 | { |
2b28c07a | 1035 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
738ed977 ZD |
1036 | basic_block dom_bb = NULL; |
1037 | edge e; | |
628f6a4e | 1038 | edge_iterator ei; |
355be0dc | 1039 | |
2b28c07a | 1040 | gcc_assert (dom_computed[dir_index]); |
d47cc544 | 1041 | |
738ed977 ZD |
1042 | if (dir == CDI_DOMINATORS) |
1043 | { | |
628f6a4e | 1044 | FOR_EACH_EDGE (e, ei, bb->preds) |
738ed977 ZD |
1045 | { |
1046 | if (!dominated_by_p (dir, e->src, bb)) | |
1047 | dom_bb = nearest_common_dominator (dir, dom_bb, e->src); | |
1048 | } | |
1049 | } | |
1050 | else | |
1051 | { | |
628f6a4e | 1052 | FOR_EACH_EDGE (e, ei, bb->succs) |
738ed977 ZD |
1053 | { |
1054 | if (!dominated_by_p (dir, e->dest, bb)) | |
1055 | dom_bb = nearest_common_dominator (dir, dom_bb, e->dest); | |
1056 | } | |
1057 | } | |
f8032688 | 1058 | |
738ed977 | 1059 | return dom_bb; |
355be0dc JH |
1060 | } |
1061 | ||
66f97d31 ZD |
1062 | /* Use simple heuristics (see iterate_fix_dominators) to determine dominators |
1063 | of BBS. We assume that all the immediate dominators except for those of the | |
1064 | blocks in BBS are correct. If CONSERVATIVE is true, we also assume that the | |
1065 | currently recorded immediate dominators of blocks in BBS really dominate the | |
1066 | blocks. The basic blocks for that we determine the dominator are removed | |
1067 | from BBS. */ | |
1068 | ||
1069 | static void | |
1070 | prune_bbs_to_update_dominators (VEC (basic_block, heap) *bbs, | |
1071 | bool conservative) | |
1072 | { | |
1073 | unsigned i; | |
1074 | bool single; | |
1075 | basic_block bb, dom = NULL; | |
1076 | edge_iterator ei; | |
1077 | edge e; | |
1078 | ||
1079 | for (i = 0; VEC_iterate (basic_block, bbs, i, bb);) | |
1080 | { | |
1081 | if (bb == ENTRY_BLOCK_PTR) | |
1082 | goto succeed; | |
1083 | ||
1084 | if (single_pred_p (bb)) | |
1085 | { | |
1086 | set_immediate_dominator (CDI_DOMINATORS, bb, single_pred (bb)); | |
1087 | goto succeed; | |
1088 | } | |
1089 | ||
1090 | if (!conservative) | |
1091 | goto fail; | |
1092 | ||
1093 | single = true; | |
1094 | dom = NULL; | |
1095 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1096 | { | |
1097 | if (dominated_by_p (CDI_DOMINATORS, e->src, bb)) | |
1098 | continue; | |
1099 | ||
1100 | if (!dom) | |
1101 | dom = e->src; | |
1102 | else | |
1103 | { | |
1104 | single = false; | |
1105 | dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src); | |
1106 | } | |
1107 | } | |
1108 | ||
1109 | gcc_assert (dom != NULL); | |
1110 | if (single | |
1111 | || find_edge (dom, bb)) | |
1112 | { | |
1113 | set_immediate_dominator (CDI_DOMINATORS, bb, dom); | |
1114 | goto succeed; | |
1115 | } | |
1116 | ||
1117 | fail: | |
1118 | i++; | |
1119 | continue; | |
1120 | ||
1121 | succeed: | |
1122 | VEC_unordered_remove (basic_block, bbs, i); | |
1123 | } | |
1124 | } | |
1125 | ||
1126 | /* Returns root of the dominance tree in the direction DIR that contains | |
1127 | BB. */ | |
1128 | ||
1129 | static basic_block | |
1130 | root_of_dom_tree (enum cdi_direction dir, basic_block bb) | |
1131 | { | |
f883e0a7 | 1132 | return (basic_block) et_root (bb->dom[dom_convert_dir_to_idx (dir)])->data; |
66f97d31 ZD |
1133 | } |
1134 | ||
1135 | /* See the comment in iterate_fix_dominators. Finds the immediate dominators | |
1136 | for the sons of Y, found using the SON and BROTHER arrays representing | |
1137 | the dominance tree of graph G. BBS maps the vertices of G to the basic | |
1138 | blocks. */ | |
1139 | ||
1140 | static void | |
1141 | determine_dominators_for_sons (struct graph *g, VEC (basic_block, heap) *bbs, | |
1142 | int y, int *son, int *brother) | |
1143 | { | |
1144 | bitmap gprime; | |
1145 | int i, a, nc; | |
1146 | VEC (int, heap) **sccs; | |
1147 | basic_block bb, dom, ybb; | |
1148 | unsigned si; | |
1149 | edge e; | |
1150 | edge_iterator ei; | |
1151 | ||
1152 | if (son[y] == -1) | |
1153 | return; | |
1154 | if (y == (int) VEC_length (basic_block, bbs)) | |
1155 | ybb = ENTRY_BLOCK_PTR; | |
1156 | else | |
1157 | ybb = VEC_index (basic_block, bbs, y); | |
1158 | ||
1159 | if (brother[son[y]] == -1) | |
1160 | { | |
1161 | /* Handle the common case Y has just one son specially. */ | |
1162 | bb = VEC_index (basic_block, bbs, son[y]); | |
1163 | set_immediate_dominator (CDI_DOMINATORS, bb, | |
1164 | recompute_dominator (CDI_DOMINATORS, bb)); | |
1165 | identify_vertices (g, y, son[y]); | |
1166 | return; | |
1167 | } | |
1168 | ||
1169 | gprime = BITMAP_ALLOC (NULL); | |
1170 | for (a = son[y]; a != -1; a = brother[a]) | |
1171 | bitmap_set_bit (gprime, a); | |
1172 | ||
1173 | nc = graphds_scc (g, gprime); | |
1174 | BITMAP_FREE (gprime); | |
1175 | ||
1176 | sccs = XCNEWVEC (VEC (int, heap) *, nc); | |
1177 | for (a = son[y]; a != -1; a = brother[a]) | |
1178 | VEC_safe_push (int, heap, sccs[g->vertices[a].component], a); | |
1179 | ||
1180 | for (i = nc - 1; i >= 0; i--) | |
1181 | { | |
1182 | dom = NULL; | |
1183 | for (si = 0; VEC_iterate (int, sccs[i], si, a); si++) | |
1184 | { | |
1185 | bb = VEC_index (basic_block, bbs, a); | |
1186 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1187 | { | |
1188 | if (root_of_dom_tree (CDI_DOMINATORS, e->src) != ybb) | |
1189 | continue; | |
1190 | ||
1191 | dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src); | |
1192 | } | |
1193 | } | |
1194 | ||
1195 | gcc_assert (dom != NULL); | |
1196 | for (si = 0; VEC_iterate (int, sccs[i], si, a); si++) | |
1197 | { | |
1198 | bb = VEC_index (basic_block, bbs, a); | |
1199 | set_immediate_dominator (CDI_DOMINATORS, bb, dom); | |
1200 | } | |
1201 | } | |
1202 | ||
1203 | for (i = 0; i < nc; i++) | |
1204 | VEC_free (int, heap, sccs[i]); | |
1205 | free (sccs); | |
1206 | ||
1207 | for (a = son[y]; a != -1; a = brother[a]) | |
1208 | identify_vertices (g, y, a); | |
1209 | } | |
1210 | ||
1211 | /* Recompute dominance information for basic blocks in the set BBS. The | |
1212 | function assumes that the immediate dominators of all the other blocks | |
1213 | in CFG are correct, and that there are no unreachable blocks. | |
1214 | ||
1215 | If CONSERVATIVE is true, we additionally assume that all the ancestors of | |
1216 | a block of BBS in the current dominance tree dominate it. */ | |
1217 | ||
355be0dc | 1218 | void |
66f97d31 ZD |
1219 | iterate_fix_dominators (enum cdi_direction dir, VEC (basic_block, heap) *bbs, |
1220 | bool conservative) | |
355be0dc | 1221 | { |
66f97d31 ZD |
1222 | unsigned i; |
1223 | basic_block bb, dom; | |
1224 | struct graph *g; | |
1225 | int n, y; | |
1226 | size_t dom_i; | |
1227 | edge e; | |
1228 | edge_iterator ei; | |
1229 | struct pointer_map_t *map; | |
1230 | int *parent, *son, *brother; | |
2b28c07a | 1231 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
355be0dc | 1232 | |
66f97d31 ZD |
1233 | /* We only support updating dominators. There are some problems with |
1234 | updating postdominators (need to add fake edges from infinite loops | |
1235 | and noreturn functions), and since we do not currently use | |
1236 | iterate_fix_dominators for postdominators, any attempt to handle these | |
1237 | problems would be unused, untested, and almost surely buggy. We keep | |
1238 | the DIR argument for consistency with the rest of the dominator analysis | |
1239 | interface. */ | |
1240 | gcc_assert (dir == CDI_DOMINATORS); | |
2b28c07a | 1241 | gcc_assert (dom_computed[dir_index]); |
d47cc544 | 1242 | |
66f97d31 ZD |
1243 | /* The algorithm we use takes inspiration from the following papers, although |
1244 | the details are quite different from any of them: | |
1245 | ||
1246 | [1] G. Ramalingam, T. Reps, An Incremental Algorithm for Maintaining the | |
1247 | Dominator Tree of a Reducible Flowgraph | |
1248 | [2] V. C. Sreedhar, G. R. Gao, Y.-F. Lee: Incremental computation of | |
1249 | dominator trees | |
1250 | [3] K. D. Cooper, T. J. Harvey and K. Kennedy: A Simple, Fast Dominance | |
1251 | Algorithm | |
1252 | ||
1253 | First, we use the following heuristics to decrease the size of the BBS | |
1254 | set: | |
1255 | a) if BB has a single predecessor, then its immediate dominator is this | |
1256 | predecessor | |
1257 | additionally, if CONSERVATIVE is true: | |
1258 | b) if all the predecessors of BB except for one (X) are dominated by BB, | |
1259 | then X is the immediate dominator of BB | |
1260 | c) if the nearest common ancestor of the predecessors of BB is X and | |
1261 | X -> BB is an edge in CFG, then X is the immediate dominator of BB | |
1262 | ||
1263 | Then, we need to establish the dominance relation among the basic blocks | |
1264 | in BBS. We split the dominance tree by removing the immediate dominator | |
0d52bcc1 | 1265 | edges from BBS, creating a forest F. We form a graph G whose vertices |
66f97d31 | 1266 | are BBS and ENTRY and X -> Y is an edge of G if there exists an edge |
0d52bcc1 | 1267 | X' -> Y in CFG such that X' belongs to the tree of the dominance forest |
66f97d31 ZD |
1268 | whose root is X. We then determine dominance tree of G. Note that |
1269 | for X, Y in BBS, X dominates Y in CFG if and only if X dominates Y in G. | |
1270 | In this step, we can use arbitrary algorithm to determine dominators. | |
1271 | We decided to prefer the algorithm [3] to the algorithm of | |
1272 | Lengauer and Tarjan, since the set BBS is usually small (rarely exceeding | |
1273 | 10 during gcc bootstrap), and [3] should perform better in this case. | |
1274 | ||
1275 | Finally, we need to determine the immediate dominators for the basic | |
1276 | blocks of BBS. If the immediate dominator of X in G is Y, then | |
1277 | the immediate dominator of X in CFG belongs to the tree of F rooted in | |
1278 | Y. We process the dominator tree T of G recursively, starting from leaves. | |
1279 | Suppose that X_1, X_2, ..., X_k are the sons of Y in T, and that the | |
1280 | subtrees of the dominance tree of CFG rooted in X_i are already correct. | |
1281 | Let G' be the subgraph of G induced by {X_1, X_2, ..., X_k}. We make | |
1282 | the following observations: | |
1283 | (i) the immediate dominator of all blocks in a strongly connected | |
1284 | component of G' is the same | |
1285 | (ii) if X has no predecessors in G', then the immediate dominator of X | |
1286 | is the nearest common ancestor of the predecessors of X in the | |
1287 | subtree of F rooted in Y | |
1288 | Therefore, it suffices to find the topological ordering of G', and | |
1289 | process the nodes X_i in this order using the rules (i) and (ii). | |
1290 | Then, we contract all the nodes X_i with Y in G, so that the further | |
1291 | steps work correctly. */ | |
1292 | ||
1293 | if (!conservative) | |
1294 | { | |
1295 | /* Split the tree now. If the idoms of blocks in BBS are not | |
1296 | conservatively correct, setting the dominators using the | |
1297 | heuristics in prune_bbs_to_update_dominators could | |
1298 | create cycles in the dominance "tree", and cause ICE. */ | |
1299 | for (i = 0; VEC_iterate (basic_block, bbs, i, bb); i++) | |
1300 | set_immediate_dominator (CDI_DOMINATORS, bb, NULL); | |
1301 | } | |
1302 | ||
1303 | prune_bbs_to_update_dominators (bbs, conservative); | |
1304 | n = VEC_length (basic_block, bbs); | |
1305 | ||
1306 | if (n == 0) | |
1307 | return; | |
e7bd94cc | 1308 | |
66f97d31 | 1309 | if (n == 1) |
355be0dc | 1310 | { |
66f97d31 ZD |
1311 | bb = VEC_index (basic_block, bbs, 0); |
1312 | set_immediate_dominator (CDI_DOMINATORS, bb, | |
1313 | recompute_dominator (CDI_DOMINATORS, bb)); | |
1314 | return; | |
1315 | } | |
1316 | ||
1317 | /* Construct the graph G. */ | |
1318 | map = pointer_map_create (); | |
1319 | for (i = 0; VEC_iterate (basic_block, bbs, i, bb); i++) | |
1320 | { | |
1321 | /* If the dominance tree is conservatively correct, split it now. */ | |
1322 | if (conservative) | |
1323 | set_immediate_dominator (CDI_DOMINATORS, bb, NULL); | |
1324 | *pointer_map_insert (map, bb) = (void *) (size_t) i; | |
1325 | } | |
1326 | *pointer_map_insert (map, ENTRY_BLOCK_PTR) = (void *) (size_t) n; | |
1327 | ||
1328 | g = new_graph (n + 1); | |
1329 | for (y = 0; y < g->n_vertices; y++) | |
1330 | g->vertices[y].data = BITMAP_ALLOC (NULL); | |
1331 | for (i = 0; VEC_iterate (basic_block, bbs, i, bb); i++) | |
1332 | { | |
1333 | FOR_EACH_EDGE (e, ei, bb->preds) | |
355be0dc | 1334 | { |
66f97d31 ZD |
1335 | dom = root_of_dom_tree (CDI_DOMINATORS, e->src); |
1336 | if (dom == bb) | |
1337 | continue; | |
1338 | ||
1339 | dom_i = (size_t) *pointer_map_contains (map, dom); | |
1340 | ||
1341 | /* Do not include parallel edges to G. */ | |
f883e0a7 | 1342 | if (bitmap_bit_p ((bitmap) g->vertices[dom_i].data, i)) |
66f97d31 ZD |
1343 | continue; |
1344 | ||
f883e0a7 | 1345 | bitmap_set_bit ((bitmap) g->vertices[dom_i].data, i); |
66f97d31 | 1346 | add_edge (g, dom_i, i); |
f8032688 MM |
1347 | } |
1348 | } | |
66f97d31 ZD |
1349 | for (y = 0; y < g->n_vertices; y++) |
1350 | BITMAP_FREE (g->vertices[y].data); | |
1351 | pointer_map_destroy (map); | |
1352 | ||
1353 | /* Find the dominator tree of G. */ | |
1354 | son = XNEWVEC (int, n + 1); | |
1355 | brother = XNEWVEC (int, n + 1); | |
1356 | parent = XNEWVEC (int, n + 1); | |
1357 | graphds_domtree (g, n, parent, son, brother); | |
1358 | ||
1359 | /* Finally, traverse the tree and find the immediate dominators. */ | |
1360 | for (y = n; son[y] != -1; y = son[y]) | |
1361 | continue; | |
1362 | while (y != -1) | |
1363 | { | |
1364 | determine_dominators_for_sons (g, bbs, y, son, brother); | |
1365 | ||
1366 | if (brother[y] != -1) | |
1367 | { | |
1368 | y = brother[y]; | |
1369 | while (son[y] != -1) | |
1370 | y = son[y]; | |
1371 | } | |
1372 | else | |
1373 | y = parent[y]; | |
1374 | } | |
1375 | ||
1376 | free (son); | |
1377 | free (brother); | |
1378 | free (parent); | |
e7bd94cc | 1379 | |
66f97d31 | 1380 | free_graph (g); |
355be0dc | 1381 | } |
f8032688 | 1382 | |
355be0dc | 1383 | void |
d47cc544 | 1384 | add_to_dominance_info (enum cdi_direction dir, basic_block bb) |
355be0dc | 1385 | { |
2b28c07a JC |
1386 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1387 | ||
1388 | gcc_assert (dom_computed[dir_index]); | |
1389 | gcc_assert (!bb->dom[dir_index]); | |
d47cc544 | 1390 | |
2b28c07a | 1391 | n_bbs_in_dom_tree[dir_index]++; |
b8698a0f | 1392 | |
2b28c07a | 1393 | bb->dom[dir_index] = et_new_tree (bb); |
d47cc544 | 1394 | |
2b28c07a JC |
1395 | if (dom_computed[dir_index] == DOM_OK) |
1396 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
1397 | } |
1398 | ||
1399 | void | |
d47cc544 SB |
1400 | delete_from_dominance_info (enum cdi_direction dir, basic_block bb) |
1401 | { | |
2b28c07a | 1402 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
d47cc544 | 1403 | |
2b28c07a | 1404 | gcc_assert (dom_computed[dir_index]); |
d47cc544 | 1405 | |
2b28c07a JC |
1406 | et_free_tree (bb->dom[dir_index]); |
1407 | bb->dom[dir_index] = NULL; | |
1408 | n_bbs_in_dom_tree[dir_index]--; | |
1409 | ||
1410 | if (dom_computed[dir_index] == DOM_OK) | |
1411 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
d47cc544 SB |
1412 | } |
1413 | ||
1414 | /* Returns the first son of BB in the dominator or postdominator tree | |
1415 | as determined by DIR. */ | |
1416 | ||
1417 | basic_block | |
1418 | first_dom_son (enum cdi_direction dir, basic_block bb) | |
355be0dc | 1419 | { |
2b28c07a JC |
1420 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1421 | struct et_node *son = bb->dom[dir_index]->son; | |
d47cc544 | 1422 | |
f883e0a7 | 1423 | return (basic_block) (son ? son->data : NULL); |
d47cc544 SB |
1424 | } |
1425 | ||
1426 | /* Returns the next dominance son after BB in the dominator or postdominator | |
1427 | tree as determined by DIR, or NULL if it was the last one. */ | |
1428 | ||
1429 | basic_block | |
1430 | next_dom_son (enum cdi_direction dir, basic_block bb) | |
1431 | { | |
2b28c07a JC |
1432 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1433 | struct et_node *next = bb->dom[dir_index]->right; | |
d47cc544 | 1434 | |
f883e0a7 | 1435 | return (basic_block) (next->father->son == next ? NULL : next->data); |
355be0dc JH |
1436 | } |
1437 | ||
2b28c07a JC |
1438 | /* Return dominance availability for dominance info DIR. */ |
1439 | ||
1440 | enum dom_state | |
1441 | dom_info_state (enum cdi_direction dir) | |
1442 | { | |
1443 | unsigned int dir_index = dom_convert_dir_to_idx (dir); | |
1444 | ||
1445 | return dom_computed[dir_index]; | |
1446 | } | |
1447 | ||
1448 | /* Set the dominance availability for dominance info DIR to NEW_STATE. */ | |
1449 | ||
1450 | void | |
1451 | set_dom_info_availability (enum cdi_direction dir, enum dom_state new_state) | |
1452 | { | |
1453 | unsigned int dir_index = dom_convert_dir_to_idx (dir); | |
1454 | ||
1455 | dom_computed[dir_index] = new_state; | |
1456 | } | |
1457 | ||
fce22de5 ZD |
1458 | /* Returns true if dominance information for direction DIR is available. */ |
1459 | ||
1460 | bool | |
1461 | dom_info_available_p (enum cdi_direction dir) | |
1462 | { | |
2b28c07a JC |
1463 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1464 | ||
1465 | return dom_computed[dir_index] != DOM_NONE; | |
fce22de5 ZD |
1466 | } |
1467 | ||
355be0dc | 1468 | void |
d47cc544 | 1469 | debug_dominance_info (enum cdi_direction dir) |
355be0dc JH |
1470 | { |
1471 | basic_block bb, bb2; | |
1472 | FOR_EACH_BB (bb) | |
d47cc544 | 1473 | if ((bb2 = get_immediate_dominator (dir, bb))) |
355be0dc | 1474 | fprintf (stderr, "%i %i\n", bb->index, bb2->index); |
f8032688 | 1475 | } |
1fc3998d ZD |
1476 | |
1477 | /* Prints to stderr representation of the dominance tree (for direction DIR) | |
cea618ac | 1478 | rooted in ROOT, indented by INDENT tabulators. If INDENT_FIRST is false, |
1fc3998d ZD |
1479 | the first line of the output is not indented. */ |
1480 | ||
1481 | static void | |
1482 | debug_dominance_tree_1 (enum cdi_direction dir, basic_block root, | |
1483 | unsigned indent, bool indent_first) | |
1484 | { | |
1485 | basic_block son; | |
1486 | unsigned i; | |
1487 | bool first = true; | |
1488 | ||
1489 | if (indent_first) | |
1490 | for (i = 0; i < indent; i++) | |
1491 | fprintf (stderr, "\t"); | |
1492 | fprintf (stderr, "%d\t", root->index); | |
1493 | ||
1494 | for (son = first_dom_son (dir, root); | |
1495 | son; | |
1496 | son = next_dom_son (dir, son)) | |
1497 | { | |
1498 | debug_dominance_tree_1 (dir, son, indent + 1, !first); | |
1499 | first = false; | |
1500 | } | |
1501 | ||
1502 | if (first) | |
1503 | fprintf (stderr, "\n"); | |
1504 | } | |
1505 | ||
1506 | /* Prints to stderr representation of the dominance tree (for direction DIR) | |
1507 | rooted in ROOT. */ | |
1508 | ||
1509 | void | |
1510 | debug_dominance_tree (enum cdi_direction dir, basic_block root) | |
1511 | { | |
1512 | debug_dominance_tree_1 (dir, root, 0, false); | |
1513 | } |