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f8032688 | 1 | /* Calculate (post)dominators in slightly super-linear time. |
a945c346 | 2 | Copyright (C) 2000-2024 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 | |
9dcd6f09 | 9 | the Free Software Foundation; either version 3, or (at your option) |
f8032688 MM |
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 | |
9dcd6f09 NC |
18 | along with GCC; see the file COPYING3. If not see |
19 | <http://www.gnu.org/licenses/>. */ | |
f8032688 MM |
20 | |
21 | /* This file implements the well known algorithm from Lengauer and Tarjan | |
22 | to compute the dominators in a control flow graph. A basic block D is said | |
23 | to dominate another block X, when all paths from the entry node of the CFG | |
24 | to X go also over D. The dominance relation is a transitive reflexive | |
25 | relation and its minimal transitive reduction is a tree, called the | |
26 | dominator tree. So for each block X besides the entry block exists a | |
27 | block I(X), called the immediate dominator of X, which is the parent of X | |
28 | in the dominator tree. | |
29 | ||
a1f300c0 | 30 | The algorithm computes this dominator tree implicitly by computing for |
f8032688 | 31 | each block its immediate dominator. We use tree balancing and path |
f3b569ca | 32 | compression, so it's the O(e*a(e,v)) variant, where a(e,v) is the very |
f8032688 MM |
33 | slowly growing functional inverse of the Ackerman function. */ |
34 | ||
35 | #include "config.h" | |
36 | #include "system.h" | |
4977bab6 | 37 | #include "coretypes.h" |
c7131fb2 | 38 | #include "backend.h" |
74c96e0c | 39 | #include "timevar.h" |
957060b5 AM |
40 | #include "diagnostic-core.h" |
41 | #include "cfganal.h" | |
42 | #include "et-forest.h" | |
66f97d31 | 43 | #include "graphds.h" |
f8032688 | 44 | |
f8032688 MM |
45 | /* We name our nodes with integers, beginning with 1. Zero is reserved for |
46 | 'undefined' or 'end of list'. The name of each node is given by the dfs | |
47 | number of the corresponding basic block. Please note, that we include the | |
48 | artificial ENTRY_BLOCK (or EXIT_BLOCK in the post-dom case) in our lists to | |
24bd1a0b | 49 | support multiple entry points. Its dfs number is of course 1. */ |
f8032688 MM |
50 | |
51 | /* Type of Basic Block aka. TBB */ | |
52 | typedef unsigned int TBB; | |
53 | ||
2321dd91 | 54 | namespace { |
f8032688 | 55 | |
2321dd91 MM |
56 | /* This class holds various arrays reflecting the (sub)structure of the |
57 | flowgraph. Most of them are of type TBB and are also indexed by TBB. */ | |
58 | ||
59 | class dom_info | |
f8032688 | 60 | { |
2321dd91 MM |
61 | public: |
62 | dom_info (function *, cdi_direction); | |
1d30acf6 | 63 | dom_info (vec <basic_block>, cdi_direction); |
2321dd91 MM |
64 | ~dom_info (); |
65 | void calc_dfs_tree (); | |
66 | void calc_idoms (); | |
67 | ||
68 | inline basic_block get_idom (basic_block); | |
69 | private: | |
70 | void calc_dfs_tree_nonrec (basic_block); | |
71 | void compress (TBB); | |
1d30acf6 | 72 | void dom_init (void); |
2321dd91 MM |
73 | TBB eval (TBB); |
74 | void link_roots (TBB, TBB); | |
75 | ||
f8032688 | 76 | /* The parent of a node in the DFS tree. */ |
2321dd91 MM |
77 | TBB *m_dfs_parent; |
78 | /* For a node x m_key[x] is roughly the node nearest to the root from which | |
f8032688 MM |
79 | exists a way to x only over nodes behind x. Such a node is also called |
80 | semidominator. */ | |
2321dd91 MM |
81 | TBB *m_key; |
82 | /* The value in m_path_min[x] is the node y on the path from x to the root of | |
83 | the tree x is in with the smallest m_key[y]. */ | |
84 | TBB *m_path_min; | |
85 | /* m_bucket[x] points to the first node of the set of nodes having x as | |
86 | key. */ | |
87 | TBB *m_bucket; | |
88 | /* And m_next_bucket[x] points to the next node. */ | |
89 | TBB *m_next_bucket; | |
90 | /* After the algorithm is done, m_dom[x] contains the immediate dominator | |
f8032688 | 91 | of x. */ |
2321dd91 | 92 | TBB *m_dom; |
f8032688 MM |
93 | |
94 | /* The following few fields implement the structures needed for disjoint | |
95 | sets. */ | |
2321dd91 MM |
96 | /* m_set_chain[x] is the next node on the path from x to the representative |
97 | of the set containing x. If m_set_chain[x]==0 then x is a root. */ | |
98 | TBB *m_set_chain; | |
99 | /* m_set_size[x] is the number of elements in the set named by x. */ | |
100 | unsigned int *m_set_size; | |
101 | /* m_set_child[x] is used for balancing the tree representing a set. It can | |
f8032688 | 102 | be understood as the next sibling of x. */ |
2321dd91 | 103 | TBB *m_set_child; |
f8032688 | 104 | |
2321dd91 | 105 | /* If b is the number of a basic block (BB->index), m_dfs_order[b] is the |
f8032688 MM |
106 | number of that node in DFS order counted from 1. This is an index |
107 | into most of the other arrays in this structure. */ | |
2321dd91 MM |
108 | TBB *m_dfs_order; |
109 | /* Points to last element in m_dfs_order array. */ | |
110 | TBB *m_dfs_last; | |
09da1532 | 111 | /* If x is the DFS-index of a node which corresponds with a basic block, |
2321dd91 MM |
112 | m_dfs_to_bb[x] is that basic block. Note, that in our structure there are |
113 | more nodes that basic blocks, so only | |
114 | m_dfs_to_bb[m_dfs_order[bb->index]]==bb is true for every basic block bb, | |
115 | but not the opposite. */ | |
116 | basic_block *m_dfs_to_bb; | |
f8032688 | 117 | |
26e0e410 | 118 | /* This is the next free DFS number when creating the DFS tree. */ |
2321dd91 MM |
119 | unsigned int m_dfsnum; |
120 | /* The number of nodes in the DFS tree (==m_dfsnum-1). */ | |
121 | unsigned int m_nodes; | |
26e0e410 RH |
122 | |
123 | /* Blocks with bits set here have a fake edge to EXIT. These are used | |
124 | to turn a DFS forest into a proper tree. */ | |
2321dd91 MM |
125 | bitmap m_fake_exit_edge; |
126 | ||
127 | /* Number of basic blocks in the function being compiled. */ | |
8e640712 | 128 | unsigned m_n_basic_blocks; |
2321dd91 MM |
129 | |
130 | /* True, if we are computing postdominators (rather than dominators). */ | |
131 | bool m_reverse; | |
132 | ||
133 | /* Start block (the entry block for forward problem, exit block for backward | |
134 | problem). */ | |
135 | basic_block m_start_block; | |
136 | /* Ending block. */ | |
137 | basic_block m_end_block; | |
f8032688 MM |
138 | }; |
139 | ||
2321dd91 | 140 | } // anonymous namespace |
f8032688 | 141 | |
2321dd91 MM |
142 | void debug_dominance_info (cdi_direction); |
143 | void debug_dominance_tree (cdi_direction, basic_block); | |
144 | ||
145 | /* Allocate and zero-initialize NUM elements of type T (T must be a | |
146 | POD-type). Note: after transition to C++11 or later, | |
147 | `x = new_zero_array <T> (num);' can be replaced with | |
148 | `x = new T[num] {};'. */ | |
149 | ||
150 | template<typename T> | |
8e640712 | 151 | inline T *new_zero_array (unsigned num) |
2321dd91 MM |
152 | { |
153 | T *result = new T[num]; | |
154 | memset (result, 0, sizeof (T) * num); | |
155 | return result; | |
156 | } | |
157 | ||
1d30acf6 | 158 | /* Helper function for constructors to initialize a part of class members. */ |
2321dd91 | 159 | |
1d30acf6 YR |
160 | void |
161 | dom_info::dom_init (void) | |
f8032688 | 162 | { |
8e640712 MS |
163 | unsigned num = m_n_basic_blocks; |
164 | ||
2321dd91 MM |
165 | m_dfs_parent = new_zero_array <TBB> (num); |
166 | m_dom = new_zero_array <TBB> (num); | |
167 | ||
168 | m_path_min = new TBB[num]; | |
169 | m_key = new TBB[num]; | |
170 | m_set_size = new unsigned int[num]; | |
8e640712 | 171 | for (unsigned i = 0; i < num; i++) |
2321dd91 MM |
172 | { |
173 | m_path_min[i] = m_key[i] = i; | |
174 | m_set_size[i] = 1; | |
175 | } | |
f8032688 | 176 | |
2321dd91 MM |
177 | m_bucket = new_zero_array <TBB> (num); |
178 | m_next_bucket = new_zero_array <TBB> (num); | |
f8032688 | 179 | |
2321dd91 MM |
180 | m_set_chain = new_zero_array <TBB> (num); |
181 | m_set_child = new_zero_array <TBB> (num); | |
f8032688 | 182 | |
2321dd91 | 183 | m_dfs_to_bb = new_zero_array <basic_block> (num); |
f8032688 | 184 | |
2321dd91 MM |
185 | m_dfsnum = 1; |
186 | m_nodes = 0; | |
1d30acf6 YR |
187 | } |
188 | ||
189 | /* Allocate all needed memory in a pessimistic fashion (so we round up). */ | |
190 | ||
191 | dom_info::dom_info (function *fn, cdi_direction dir) | |
192 | { | |
193 | m_n_basic_blocks = n_basic_blocks_for_fn (fn); | |
194 | ||
195 | dom_init (); | |
196 | ||
197 | unsigned last_bb_index = last_basic_block_for_fn (fn); | |
198 | m_dfs_order = new_zero_array <TBB> (last_bb_index + 1); | |
199 | m_dfs_last = &m_dfs_order[last_bb_index]; | |
26e0e410 | 200 | |
2b28c07a JC |
201 | switch (dir) |
202 | { | |
203 | case CDI_DOMINATORS: | |
2321dd91 MM |
204 | m_reverse = false; |
205 | m_fake_exit_edge = NULL; | |
206 | m_start_block = ENTRY_BLOCK_PTR_FOR_FN (fn); | |
207 | m_end_block = EXIT_BLOCK_PTR_FOR_FN (fn); | |
2b28c07a JC |
208 | break; |
209 | case CDI_POST_DOMINATORS: | |
2321dd91 MM |
210 | m_reverse = true; |
211 | m_fake_exit_edge = BITMAP_ALLOC (NULL); | |
212 | m_start_block = EXIT_BLOCK_PTR_FOR_FN (fn); | |
213 | m_end_block = ENTRY_BLOCK_PTR_FOR_FN (fn); | |
2b28c07a JC |
214 | break; |
215 | default: | |
216 | gcc_unreachable (); | |
2b28c07a | 217 | } |
f8032688 MM |
218 | } |
219 | ||
1d30acf6 YR |
220 | /* Constructor for reducible region REGION. */ |
221 | ||
222 | dom_info::dom_info (vec<basic_block> region, cdi_direction dir) | |
223 | { | |
224 | m_n_basic_blocks = region.length (); | |
8e640712 | 225 | unsigned nm1 = m_n_basic_blocks - 1; |
1d30acf6 YR |
226 | |
227 | dom_init (); | |
228 | ||
229 | /* Determine max basic block index in region. */ | |
230 | int max_index = region[0]->index; | |
8e640712 | 231 | for (unsigned i = 1; i <= nm1; i++) |
1d30acf6 YR |
232 | if (region[i]->index > max_index) |
233 | max_index = region[i]->index; | |
234 | max_index += 1; /* set index on the first bb out of region. */ | |
235 | ||
236 | m_dfs_order = new_zero_array <TBB> (max_index + 1); | |
237 | m_dfs_last = &m_dfs_order[max_index]; | |
238 | ||
239 | m_fake_exit_edge = NULL; /* Assume that region is reducible. */ | |
240 | ||
241 | switch (dir) | |
242 | { | |
243 | case CDI_DOMINATORS: | |
244 | m_reverse = false; | |
245 | m_start_block = region[0]; | |
246 | m_end_block = region[nm1]; | |
247 | break; | |
248 | case CDI_POST_DOMINATORS: | |
249 | m_reverse = true; | |
250 | m_start_block = region[nm1]; | |
251 | m_end_block = region[0]; | |
252 | break; | |
253 | default: | |
254 | gcc_unreachable (); | |
255 | } | |
256 | } | |
257 | ||
2321dd91 MM |
258 | inline basic_block |
259 | dom_info::get_idom (basic_block bb) | |
260 | { | |
261 | TBB d = m_dom[m_dfs_order[bb->index]]; | |
262 | return m_dfs_to_bb[d]; | |
263 | } | |
f8032688 | 264 | |
2b28c07a JC |
265 | /* Map dominance calculation type to array index used for various |
266 | dominance information arrays. This version is simple -- it will need | |
267 | to be modified, obviously, if additional values are added to | |
268 | cdi_direction. */ | |
269 | ||
2321dd91 MM |
270 | static inline unsigned int |
271 | dom_convert_dir_to_idx (cdi_direction dir) | |
2b28c07a | 272 | { |
2ba31c05 | 273 | gcc_checking_assert (dir == CDI_DOMINATORS || dir == CDI_POST_DOMINATORS); |
2b28c07a JC |
274 | return dir - 1; |
275 | } | |
276 | ||
2321dd91 | 277 | /* Free all allocated memory in dom_info. */ |
f8032688 | 278 | |
2321dd91 | 279 | dom_info::~dom_info () |
f8032688 | 280 | { |
2321dd91 MM |
281 | delete[] m_dfs_parent; |
282 | delete[] m_path_min; | |
283 | delete[] m_key; | |
284 | delete[] m_dom; | |
285 | delete[] m_bucket; | |
286 | delete[] m_next_bucket; | |
287 | delete[] m_set_chain; | |
288 | delete[] m_set_size; | |
289 | delete[] m_set_child; | |
290 | delete[] m_dfs_order; | |
291 | delete[] m_dfs_to_bb; | |
292 | BITMAP_FREE (m_fake_exit_edge); | |
f8032688 MM |
293 | } |
294 | ||
2321dd91 MM |
295 | /* The nonrecursive variant of creating a DFS tree. BB is the starting basic |
296 | block for this tree and m_reverse is true, if predecessors should be visited | |
297 | instead of successors of a node. After this is done all nodes reachable | |
298 | from BB were visited, have assigned their dfs number and are linked together | |
299 | to form a tree. */ | |
f8032688 | 300 | |
2321dd91 MM |
301 | void |
302 | dom_info::calc_dfs_tree_nonrec (basic_block bb) | |
f8032688 | 303 | { |
2321dd91 MM |
304 | edge_iterator *stack = new edge_iterator[m_n_basic_blocks + 1]; |
305 | int sp = 0; | |
1d30acf6 YR |
306 | unsigned d_i = dom_convert_dir_to_idx (m_reverse ? CDI_POST_DOMINATORS |
307 | : CDI_DOMINATORS); | |
f8032688 | 308 | |
2321dd91 MM |
309 | /* Initialize the first edge. */ |
310 | edge_iterator ei = m_reverse ? ei_start (bb->preds) | |
311 | : ei_start (bb->succs); | |
f8032688 MM |
312 | |
313 | /* When the stack is empty we break out of this loop. */ | |
314 | while (1) | |
315 | { | |
316 | basic_block bn; | |
2321dd91 | 317 | edge_iterator einext; |
f8032688 MM |
318 | |
319 | /* This loop traverses edges e in depth first manner, and fills the | |
320 | stack. */ | |
628f6a4e | 321 | while (!ei_end_p (ei)) |
f8032688 | 322 | { |
2321dd91 | 323 | edge e = ei_edge (ei); |
f8032688 MM |
324 | |
325 | /* Deduce from E the current and the next block (BB and BN), and the | |
326 | next edge. */ | |
2321dd91 | 327 | if (m_reverse) |
f8032688 MM |
328 | { |
329 | bn = e->src; | |
330 | ||
331 | /* If the next node BN is either already visited or a border | |
1d30acf6 YR |
332 | block or out of region the current edge is useless, and simply |
333 | overwritten with the next edge out of the current node. */ | |
334 | if (bn == m_end_block || bn->dom[d_i] == NULL | |
335 | || m_dfs_order[bn->index]) | |
f8032688 | 336 | { |
628f6a4e | 337 | ei_next (&ei); |
f8032688 MM |
338 | continue; |
339 | } | |
340 | bb = e->dest; | |
628f6a4e | 341 | einext = ei_start (bn->preds); |
f8032688 MM |
342 | } |
343 | else | |
344 | { | |
345 | bn = e->dest; | |
1d30acf6 YR |
346 | if (bn == m_end_block || bn->dom[d_i] == NULL |
347 | || m_dfs_order[bn->index]) | |
f8032688 | 348 | { |
628f6a4e | 349 | ei_next (&ei); |
f8032688 MM |
350 | continue; |
351 | } | |
352 | bb = e->src; | |
628f6a4e | 353 | einext = ei_start (bn->succs); |
f8032688 MM |
354 | } |
355 | ||
2321dd91 | 356 | gcc_assert (bn != m_start_block); |
f8032688 MM |
357 | |
358 | /* Fill the DFS tree info calculatable _before_ recursing. */ | |
2321dd91 MM |
359 | TBB my_i; |
360 | if (bb != m_start_block) | |
361 | my_i = m_dfs_order[bb->index]; | |
f8032688 | 362 | else |
2321dd91 MM |
363 | my_i = *m_dfs_last; |
364 | TBB child_i = m_dfs_order[bn->index] = m_dfsnum++; | |
365 | m_dfs_to_bb[child_i] = bn; | |
366 | m_dfs_parent[child_i] = my_i; | |
f8032688 MM |
367 | |
368 | /* Save the current point in the CFG on the stack, and recurse. */ | |
628f6a4e BE |
369 | stack[sp++] = ei; |
370 | ei = einext; | |
f8032688 MM |
371 | } |
372 | ||
373 | if (!sp) | |
374 | break; | |
628f6a4e | 375 | ei = stack[--sp]; |
f8032688 MM |
376 | |
377 | /* OK. The edge-list was exhausted, meaning normally we would | |
378 | end the recursion. After returning from the recursive call, | |
379 | there were (may be) other statements which were run after a | |
380 | child node was completely considered by DFS. Here is the | |
381 | point to do it in the non-recursive variant. | |
382 | E.g. The block just completed is in e->dest for forward DFS, | |
383 | the block not yet completed (the parent of the one above) | |
384 | in e->src. This could be used e.g. for computing the number of | |
385 | descendants or the tree depth. */ | |
628f6a4e | 386 | ei_next (&ei); |
f8032688 | 387 | } |
2321dd91 | 388 | delete[] stack; |
f8032688 MM |
389 | } |
390 | ||
2321dd91 MM |
391 | /* The main entry for calculating the DFS tree or forest. m_reverse is true, |
392 | if we are interested in the reverse flow graph. In that case the result is | |
393 | not necessarily a tree but a forest, because there may be nodes from which | |
394 | the EXIT_BLOCK is unreachable. */ | |
f8032688 | 395 | |
2321dd91 MM |
396 | void |
397 | dom_info::calc_dfs_tree () | |
f8032688 | 398 | { |
2321dd91 MM |
399 | *m_dfs_last = m_dfsnum; |
400 | m_dfs_to_bb[m_dfsnum] = m_start_block; | |
401 | m_dfsnum++; | |
f8032688 | 402 | |
2321dd91 | 403 | calc_dfs_tree_nonrec (m_start_block); |
f8032688 | 404 | |
1d30acf6 | 405 | if (m_fake_exit_edge) |
f8032688 MM |
406 | { |
407 | /* In the post-dom case we may have nodes without a path to EXIT_BLOCK. | |
408 | They are reverse-unreachable. In the dom-case we disallow such | |
26e0e410 RH |
409 | nodes, but in post-dom we have to deal with them. |
410 | ||
411 | There are two situations in which this occurs. First, noreturn | |
412 | functions. Second, infinite loops. In the first case we need to | |
413 | pretend that there is an edge to the exit block. In the second | |
414 | case, we wind up with a forest. We need to process all noreturn | |
415 | blocks before we know if we've got any infinite loops. */ | |
416 | ||
e0082a72 | 417 | basic_block b; |
26e0e410 RH |
418 | bool saw_unconnected = false; |
419 | ||
2321dd91 | 420 | FOR_BB_BETWEEN (b, m_start_block->prev_bb, m_end_block, prev_bb) |
f8032688 | 421 | { |
628f6a4e | 422 | if (EDGE_COUNT (b->succs) > 0) |
26e0e410 | 423 | { |
2321dd91 | 424 | if (m_dfs_order[b->index] == 0) |
26e0e410 RH |
425 | saw_unconnected = true; |
426 | continue; | |
427 | } | |
2321dd91 MM |
428 | bitmap_set_bit (m_fake_exit_edge, b->index); |
429 | m_dfs_order[b->index] = m_dfsnum; | |
430 | m_dfs_to_bb[m_dfsnum] = b; | |
431 | m_dfs_parent[m_dfsnum] = *m_dfs_last; | |
432 | m_dfsnum++; | |
433 | calc_dfs_tree_nonrec (b); | |
f8032688 | 434 | } |
26e0e410 RH |
435 | |
436 | if (saw_unconnected) | |
437 | { | |
2321dd91 | 438 | FOR_BB_BETWEEN (b, m_start_block->prev_bb, m_end_block, prev_bb) |
26e0e410 | 439 | { |
2321dd91 | 440 | if (m_dfs_order[b->index]) |
26e0e410 | 441 | continue; |
2321dd91 MM |
442 | basic_block b2 = dfs_find_deadend (b); |
443 | gcc_checking_assert (m_dfs_order[b2->index] == 0); | |
444 | bitmap_set_bit (m_fake_exit_edge, b2->index); | |
445 | m_dfs_order[b2->index] = m_dfsnum; | |
446 | m_dfs_to_bb[m_dfsnum] = b2; | |
447 | m_dfs_parent[m_dfsnum] = *m_dfs_last; | |
448 | m_dfsnum++; | |
449 | calc_dfs_tree_nonrec (b2); | |
450 | gcc_checking_assert (m_dfs_order[b->index]); | |
26e0e410 RH |
451 | } |
452 | } | |
f8032688 MM |
453 | } |
454 | ||
2321dd91 | 455 | m_nodes = m_dfsnum - 1; |
f8032688 | 456 | |
24bd1a0b | 457 | /* This aborts e.g. when there is _no_ path from ENTRY to EXIT at all. */ |
2321dd91 | 458 | gcc_assert (m_nodes == (unsigned int) m_n_basic_blocks - 1); |
f8032688 MM |
459 | } |
460 | ||
461 | /* Compress the path from V to the root of its set and update path_min at the | |
462 | same time. After compress(di, V) set_chain[V] is the root of the set V is | |
463 | in and path_min[V] is the node with the smallest key[] value on the path | |
464 | from V to that root. */ | |
465 | ||
2321dd91 MM |
466 | void |
467 | dom_info::compress (TBB v) | |
f8032688 MM |
468 | { |
469 | /* Btw. It's not worth to unrecurse compress() as the depth is usually not | |
470 | greater than 5 even for huge graphs (I've not seen call depth > 4). | |
471 | Also performance wise compress() ranges _far_ behind eval(). */ | |
2321dd91 MM |
472 | TBB parent = m_set_chain[v]; |
473 | if (m_set_chain[parent]) | |
f8032688 | 474 | { |
2321dd91 MM |
475 | compress (parent); |
476 | if (m_key[m_path_min[parent]] < m_key[m_path_min[v]]) | |
477 | m_path_min[v] = m_path_min[parent]; | |
478 | m_set_chain[v] = m_set_chain[parent]; | |
f8032688 MM |
479 | } |
480 | } | |
481 | ||
482 | /* Compress the path from V to the set root of V if needed (when the root has | |
483 | changed since the last call). Returns the node with the smallest key[] | |
484 | value on the path from V to the root. */ | |
485 | ||
2321dd91 MM |
486 | inline TBB |
487 | dom_info::eval (TBB v) | |
f8032688 | 488 | { |
fa10beec | 489 | /* The representative of the set V is in, also called root (as the set |
f8032688 | 490 | representation is a tree). */ |
2321dd91 | 491 | TBB rep = m_set_chain[v]; |
f8032688 MM |
492 | |
493 | /* V itself is the root. */ | |
494 | if (!rep) | |
2321dd91 | 495 | return m_path_min[v]; |
f8032688 MM |
496 | |
497 | /* Compress only if necessary. */ | |
2321dd91 | 498 | if (m_set_chain[rep]) |
f8032688 | 499 | { |
2321dd91 MM |
500 | compress (v); |
501 | rep = m_set_chain[v]; | |
f8032688 MM |
502 | } |
503 | ||
2321dd91 MM |
504 | if (m_key[m_path_min[rep]] >= m_key[m_path_min[v]]) |
505 | return m_path_min[v]; | |
f8032688 | 506 | else |
2321dd91 | 507 | return m_path_min[rep]; |
f8032688 MM |
508 | } |
509 | ||
510 | /* This essentially merges the two sets of V and W, giving a single set with | |
511 | the new root V. The internal representation of these disjoint sets is a | |
512 | balanced tree. Currently link(V,W) is only used with V being the parent | |
513 | of W. */ | |
514 | ||
2321dd91 MM |
515 | void |
516 | dom_info::link_roots (TBB v, TBB w) | |
f8032688 MM |
517 | { |
518 | TBB s = w; | |
519 | ||
520 | /* Rebalance the tree. */ | |
2321dd91 | 521 | while (m_key[m_path_min[w]] < m_key[m_path_min[m_set_child[s]]]) |
f8032688 | 522 | { |
2321dd91 MM |
523 | if (m_set_size[s] + m_set_size[m_set_child[m_set_child[s]]] |
524 | >= 2 * m_set_size[m_set_child[s]]) | |
f8032688 | 525 | { |
2321dd91 MM |
526 | m_set_chain[m_set_child[s]] = s; |
527 | m_set_child[s] = m_set_child[m_set_child[s]]; | |
f8032688 MM |
528 | } |
529 | else | |
530 | { | |
2321dd91 MM |
531 | m_set_size[m_set_child[s]] = m_set_size[s]; |
532 | s = m_set_chain[s] = m_set_child[s]; | |
f8032688 MM |
533 | } |
534 | } | |
535 | ||
2321dd91 MM |
536 | m_path_min[s] = m_path_min[w]; |
537 | m_set_size[v] += m_set_size[w]; | |
538 | if (m_set_size[v] < 2 * m_set_size[w]) | |
539 | std::swap (m_set_child[v], s); | |
f8032688 MM |
540 | |
541 | /* Merge all subtrees. */ | |
542 | while (s) | |
543 | { | |
2321dd91 MM |
544 | m_set_chain[s] = v; |
545 | s = m_set_child[s]; | |
f8032688 MM |
546 | } |
547 | } | |
548 | ||
2321dd91 MM |
549 | /* This calculates the immediate dominators (or post-dominators). THIS is our |
550 | working structure and should hold the DFS forest. | |
551 | On return the immediate dominator to node V is in m_dom[V]. */ | |
f8032688 | 552 | |
2321dd91 MM |
553 | void |
554 | dom_info::calc_idoms () | |
f8032688 | 555 | { |
f8032688 | 556 | /* Go backwards in DFS order, to first look at the leafs. */ |
2321dd91 | 557 | for (TBB v = m_nodes; v > 1; v--) |
f8032688 | 558 | { |
2321dd91 | 559 | basic_block bb = m_dfs_to_bb[v]; |
628f6a4e | 560 | edge e; |
f8032688 | 561 | |
2321dd91 MM |
562 | TBB par = m_dfs_parent[v]; |
563 | TBB k = v; | |
628f6a4e | 564 | |
2321dd91 MM |
565 | edge_iterator ei = m_reverse ? ei_start (bb->succs) |
566 | : ei_start (bb->preds); | |
567 | edge_iterator einext; | |
628f6a4e | 568 | |
1d30acf6 | 569 | if (m_fake_exit_edge) |
26e0e410 | 570 | { |
26e0e410 | 571 | /* If this block has a fake edge to exit, process that first. */ |
2321dd91 | 572 | if (bitmap_bit_p (m_fake_exit_edge, bb->index)) |
26e0e410 | 573 | { |
628f6a4e BE |
574 | einext = ei; |
575 | einext.index = 0; | |
26e0e410 RH |
576 | goto do_fake_exit_edge; |
577 | } | |
578 | } | |
f8032688 MM |
579 | |
580 | /* Search all direct predecessors for the smallest node with a path | |
581 | to them. That way we have the smallest node with also a path to | |
582 | us only over nodes behind us. In effect we search for our | |
583 | semidominator. */ | |
628f6a4e | 584 | while (!ei_end_p (ei)) |
f8032688 | 585 | { |
f8032688 | 586 | basic_block b; |
2321dd91 | 587 | TBB k1; |
f8032688 | 588 | |
628f6a4e | 589 | e = ei_edge (ei); |
2321dd91 | 590 | b = m_reverse ? e->dest : e->src; |
628f6a4e BE |
591 | einext = ei; |
592 | ei_next (&einext); | |
593 | ||
2321dd91 | 594 | if (b == m_start_block) |
26e0e410 RH |
595 | { |
596 | do_fake_exit_edge: | |
2321dd91 | 597 | k1 = *m_dfs_last; |
26e0e410 | 598 | } |
f8032688 | 599 | else |
2321dd91 | 600 | k1 = m_dfs_order[b->index]; |
f8032688 MM |
601 | |
602 | /* Call eval() only if really needed. If k1 is above V in DFS tree, | |
603 | then we know, that eval(k1) == k1 and key[k1] == k1. */ | |
604 | if (k1 > v) | |
2321dd91 | 605 | k1 = m_key[eval (k1)]; |
f8032688 MM |
606 | if (k1 < k) |
607 | k = k1; | |
628f6a4e BE |
608 | |
609 | ei = einext; | |
f8032688 MM |
610 | } |
611 | ||
2321dd91 MM |
612 | m_key[v] = k; |
613 | link_roots (par, v); | |
614 | m_next_bucket[v] = m_bucket[k]; | |
615 | m_bucket[k] = v; | |
f8032688 MM |
616 | |
617 | /* Transform semidominators into dominators. */ | |
2321dd91 | 618 | for (TBB w = m_bucket[par]; w; w = m_next_bucket[w]) |
f8032688 | 619 | { |
2321dd91 MM |
620 | k = eval (w); |
621 | if (m_key[k] < m_key[w]) | |
622 | m_dom[w] = k; | |
f8032688 | 623 | else |
2321dd91 | 624 | m_dom[w] = par; |
f8032688 MM |
625 | } |
626 | /* We don't need to cleanup next_bucket[]. */ | |
2321dd91 | 627 | m_bucket[par] = 0; |
f8032688 MM |
628 | } |
629 | ||
a1f300c0 | 630 | /* Explicitly define the dominators. */ |
2321dd91 MM |
631 | m_dom[1] = 0; |
632 | for (TBB v = 2; v <= m_nodes; v++) | |
633 | if (m_dom[v] != m_key[v]) | |
634 | m_dom[v] = m_dom[m_dom[v]]; | |
f8032688 MM |
635 | } |
636 | ||
d47cc544 SB |
637 | /* Assign dfs numbers starting from NUM to NODE and its sons. */ |
638 | ||
639 | static void | |
640 | assign_dfs_numbers (struct et_node *node, int *num) | |
641 | { | |
97258480 RB |
642 | et_node *n = node; |
643 | while (1) | |
d47cc544 | 644 | { |
97258480 RB |
645 | n->dfs_num_in = (*num)++; |
646 | if (n->son) | |
647 | n = n->son; | |
648 | else | |
649 | { | |
650 | while (!n->right || n->right == n->father->son) | |
651 | { | |
652 | n->dfs_num_out = (*num)++; | |
653 | if (n == node) | |
654 | return; | |
655 | n = n->father; | |
656 | } | |
657 | n->dfs_num_out = (*num)++; | |
658 | n = n->right; | |
659 | } | |
d47cc544 | 660 | } |
d47cc544 | 661 | } |
f8032688 | 662 | |
5d3cc252 | 663 | /* Compute the data necessary for fast resolving of dominator queries in a |
d47cc544 | 664 | static dominator tree. */ |
f8032688 | 665 | |
d47cc544 SB |
666 | static void |
667 | compute_dom_fast_query (enum cdi_direction dir) | |
668 | { | |
669 | int num = 0; | |
670 | basic_block bb; | |
2b28c07a | 671 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
d47cc544 | 672 | |
2ba31c05 | 673 | gcc_checking_assert (dom_info_available_p (dir)); |
d47cc544 | 674 | |
2b28c07a | 675 | if (dom_computed[dir_index] == DOM_OK) |
d47cc544 SB |
676 | return; |
677 | ||
04a90bec | 678 | FOR_ALL_BB_FN (bb, cfun) |
d47cc544 | 679 | { |
2b28c07a JC |
680 | if (!bb->dom[dir_index]->father) |
681 | assign_dfs_numbers (bb->dom[dir_index], &num); | |
d47cc544 SB |
682 | } |
683 | ||
2b28c07a | 684 | dom_computed[dir_index] = DOM_OK; |
d47cc544 SB |
685 | } |
686 | ||
1d30acf6 YR |
687 | /* Analogous to the previous function but compute the data for reducible |
688 | region REGION. */ | |
689 | ||
690 | static void | |
691 | compute_dom_fast_query_in_region (enum cdi_direction dir, | |
692 | vec<basic_block> region) | |
693 | { | |
694 | int num = 0; | |
695 | basic_block bb; | |
696 | unsigned int dir_index = dom_convert_dir_to_idx (dir); | |
697 | ||
698 | gcc_checking_assert (dom_info_available_p (dir)); | |
699 | ||
700 | if (dom_computed[dir_index] == DOM_OK) | |
701 | return; | |
702 | ||
703 | /* Assign dfs numbers for region nodes except for entry and exit nodes. */ | |
704 | for (unsigned int i = 1; i < region.length () - 1; i++) | |
705 | { | |
706 | bb = region[i]; | |
707 | if (!bb->dom[dir_index]->father) | |
708 | assign_dfs_numbers (bb->dom[dir_index], &num); | |
709 | } | |
710 | ||
711 | dom_computed[dir_index] = DOM_OK; | |
712 | } | |
713 | ||
d47cc544 | 714 | /* The main entry point into this module. DIR is set depending on whether |
f31fa9ea RB |
715 | we want to compute dominators or postdominators. If COMPUTE_FAST_QUERY |
716 | is false then the DFS numbers allowing for a O(1) dominance query | |
717 | are not computed. */ | |
d47cc544 SB |
718 | |
719 | void | |
f31fa9ea | 720 | calculate_dominance_info (cdi_direction dir, bool compute_fast_query) |
f8032688 | 721 | { |
2b28c07a | 722 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
355be0dc | 723 | |
2b28c07a | 724 | if (dom_computed[dir_index] == DOM_OK) |
f3c676e1 | 725 | { |
b2b29377 | 726 | checking_verify_dominators (dir); |
f3c676e1 TV |
727 | return; |
728 | } | |
355be0dc | 729 | |
74c96e0c | 730 | timevar_push (TV_DOMINANCE); |
fce22de5 | 731 | if (!dom_info_available_p (dir)) |
d47cc544 | 732 | { |
2b28c07a | 733 | gcc_assert (!n_bbs_in_dom_tree[dir_index]); |
f8032688 | 734 | |
2321dd91 | 735 | basic_block b; |
04a90bec | 736 | FOR_ALL_BB_FN (b, cfun) |
d47cc544 | 737 | { |
2b28c07a | 738 | b->dom[dir_index] = et_new_tree (b); |
d47cc544 | 739 | } |
0cae8d31 | 740 | n_bbs_in_dom_tree[dir_index] = n_basic_blocks_for_fn (cfun); |
f8032688 | 741 | |
2321dd91 MM |
742 | dom_info di (cfun, dir); |
743 | di.calc_dfs_tree (); | |
744 | di.calc_idoms (); | |
355be0dc | 745 | |
11cd3bed | 746 | FOR_EACH_BB_FN (b, cfun) |
d47cc544 | 747 | { |
2321dd91 MM |
748 | if (basic_block d = di.get_idom (b)) |
749 | et_set_father (b->dom[dir_index], d->dom[dir_index]); | |
d47cc544 | 750 | } |
e0082a72 | 751 | |
2b28c07a | 752 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; |
355be0dc | 753 | } |
4081bdd2 | 754 | else |
b2b29377 | 755 | checking_verify_dominators (dir); |
355be0dc | 756 | |
f31fa9ea RB |
757 | if (compute_fast_query) |
758 | compute_dom_fast_query (dir); | |
74c96e0c ZD |
759 | |
760 | timevar_pop (TV_DOMINANCE); | |
355be0dc JH |
761 | } |
762 | ||
1d30acf6 YR |
763 | /* Analogous to the previous function but compute dominance info for regions |
764 | which are single entry, multiple exit regions for CDI_DOMINATORs and | |
765 | multiple entry, single exit regions for CDI_POST_DOMINATORs. */ | |
766 | ||
767 | void | |
768 | calculate_dominance_info_for_region (cdi_direction dir, | |
769 | vec<basic_block> region) | |
770 | { | |
771 | unsigned int dir_index = dom_convert_dir_to_idx (dir); | |
772 | basic_block bb; | |
773 | unsigned int i; | |
774 | ||
775 | if (dom_computed[dir_index] == DOM_OK) | |
776 | return; | |
777 | ||
778 | timevar_push (TV_DOMINANCE); | |
779 | /* Assume that dom info is not partially computed. */ | |
780 | gcc_assert (!dom_info_available_p (dir)); | |
781 | ||
782 | FOR_EACH_VEC_ELT (region, i, bb) | |
783 | { | |
784 | bb->dom[dir_index] = et_new_tree (bb); | |
785 | } | |
786 | dom_info di (region, dir); | |
787 | di.calc_dfs_tree (); | |
788 | di.calc_idoms (); | |
789 | ||
790 | FOR_EACH_VEC_ELT (region, i, bb) | |
791 | if (basic_block d = di.get_idom (bb)) | |
792 | et_set_father (bb->dom[dir_index], d->dom[dir_index]); | |
793 | ||
794 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
795 | compute_dom_fast_query_in_region (dir, region); | |
796 | ||
797 | timevar_pop (TV_DOMINANCE); | |
798 | } | |
799 | ||
d47cc544 | 800 | /* Free dominance information for direction DIR. */ |
355be0dc | 801 | void |
e3f613cb | 802 | free_dominance_info (function *fn, enum cdi_direction dir) |
355be0dc JH |
803 | { |
804 | basic_block bb; | |
2b28c07a | 805 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
355be0dc | 806 | |
e3f613cb | 807 | if (!dom_info_available_p (fn, dir)) |
d47cc544 SB |
808 | return; |
809 | ||
e3f613cb | 810 | FOR_ALL_BB_FN (bb, fn) |
d47cc544 | 811 | { |
2b28c07a JC |
812 | et_free_tree_force (bb->dom[dir_index]); |
813 | bb->dom[dir_index] = NULL; | |
d47cc544 | 814 | } |
5a6ccafd | 815 | et_free_pools (); |
d47cc544 | 816 | |
e3f613cb RB |
817 | fn->cfg->x_n_bbs_in_dom_tree[dir_index] = 0; |
818 | ||
819 | fn->cfg->x_dom_computed[dir_index] = DOM_NONE; | |
820 | } | |
6de9cd9a | 821 | |
e3f613cb RB |
822 | void |
823 | free_dominance_info (enum cdi_direction dir) | |
824 | { | |
825 | free_dominance_info (cfun, dir); | |
355be0dc JH |
826 | } |
827 | ||
1d30acf6 YR |
828 | /* Free dominance information for direction DIR in region REGION. */ |
829 | ||
830 | void | |
831 | free_dominance_info_for_region (function *fn, | |
832 | enum cdi_direction dir, | |
833 | vec<basic_block> region) | |
834 | { | |
835 | basic_block bb; | |
836 | unsigned int i; | |
837 | unsigned int dir_index = dom_convert_dir_to_idx (dir); | |
838 | ||
839 | if (!dom_info_available_p (dir)) | |
840 | return; | |
841 | ||
842 | FOR_EACH_VEC_ELT (region, i, bb) | |
843 | { | |
844 | et_free_tree_force (bb->dom[dir_index]); | |
845 | bb->dom[dir_index] = NULL; | |
846 | } | |
847 | et_free_pools (); | |
848 | ||
849 | fn->cfg->x_dom_computed[dir_index] = DOM_NONE; | |
850 | ||
851 | fn->cfg->x_n_bbs_in_dom_tree[dir_index] = 0; | |
852 | } | |
853 | ||
355be0dc JH |
854 | /* Return the immediate dominator of basic block BB. */ |
855 | basic_block | |
d47cc544 | 856 | get_immediate_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 857 | { |
2b28c07a JC |
858 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
859 | struct et_node *node = bb->dom[dir_index]; | |
d47cc544 | 860 | |
2ba31c05 | 861 | gcc_checking_assert (dom_computed[dir_index]); |
d47cc544 SB |
862 | |
863 | if (!node->father) | |
864 | return NULL; | |
865 | ||
f883e0a7 | 866 | return (basic_block) node->father->data; |
355be0dc JH |
867 | } |
868 | ||
869 | /* Set the immediate dominator of the block possibly removing | |
870 | existing edge. NULL can be used to remove any edge. */ | |
7031a8b9 | 871 | void |
d47cc544 SB |
872 | set_immediate_dominator (enum cdi_direction dir, basic_block bb, |
873 | basic_block dominated_by) | |
355be0dc | 874 | { |
2b28c07a JC |
875 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
876 | struct et_node *node = bb->dom[dir_index]; | |
b8698a0f | 877 | |
2ba31c05 | 878 | gcc_checking_assert (dom_computed[dir_index]); |
355be0dc | 879 | |
d47cc544 | 880 | if (node->father) |
355be0dc | 881 | { |
d47cc544 | 882 | if (node->father->data == dominated_by) |
6de9cd9a | 883 | return; |
d47cc544 | 884 | et_split (node); |
355be0dc | 885 | } |
d47cc544 SB |
886 | |
887 | if (dominated_by) | |
2b28c07a | 888 | et_set_father (node, dominated_by->dom[dir_index]); |
d47cc544 | 889 | |
2b28c07a JC |
890 | if (dom_computed[dir_index] == DOM_OK) |
891 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
892 | } |
893 | ||
66f97d31 ZD |
894 | /* Returns the list of basic blocks immediately dominated by BB, in the |
895 | direction DIR. */ | |
4f899c42 | 896 | auto_vec<basic_block> |
66f97d31 | 897 | get_dominated_by (enum cdi_direction dir, basic_block bb) |
355be0dc | 898 | { |
66f97d31 | 899 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
2b28c07a | 900 | struct et_node *node = bb->dom[dir_index], *son = node->son, *ason; |
4f899c42 | 901 | auto_vec<basic_block> bbs; |
66f97d31 | 902 | |
2ba31c05 | 903 | gcc_checking_assert (dom_computed[dir_index]); |
d47cc544 SB |
904 | |
905 | if (!son) | |
4f899c42 | 906 | return bbs; |
d47cc544 | 907 | |
9771b263 | 908 | bbs.safe_push ((basic_block) son->data); |
2d888286 | 909 | for (ason = son->right; ason != son; ason = ason->right) |
9771b263 | 910 | bbs.safe_push ((basic_block) ason->data); |
355be0dc | 911 | |
66f97d31 | 912 | return bbs; |
355be0dc JH |
913 | } |
914 | ||
66f97d31 ZD |
915 | /* Returns the list of basic blocks that are immediately dominated (in |
916 | direction DIR) by some block between N_REGION ones stored in REGION, | |
917 | except for blocks in the REGION itself. */ | |
b8698a0f | 918 | |
4541b5ec | 919 | auto_vec<basic_block> |
42759f1e | 920 | get_dominated_by_region (enum cdi_direction dir, basic_block *region, |
66f97d31 | 921 | unsigned n_region) |
42759f1e | 922 | { |
66f97d31 | 923 | unsigned i; |
42759f1e | 924 | basic_block dom; |
4541b5ec | 925 | auto_vec<basic_block> doms; |
42759f1e ZD |
926 | |
927 | for (i = 0; i < n_region; i++) | |
6580ee77 | 928 | region[i]->flags |= BB_DUPLICATED; |
42759f1e ZD |
929 | for (i = 0; i < n_region; i++) |
930 | for (dom = first_dom_son (dir, region[i]); | |
931 | dom; | |
932 | dom = next_dom_son (dir, dom)) | |
6580ee77 | 933 | if (!(dom->flags & BB_DUPLICATED)) |
9771b263 | 934 | doms.safe_push (dom); |
42759f1e | 935 | for (i = 0; i < n_region; i++) |
6580ee77 | 936 | region[i]->flags &= ~BB_DUPLICATED; |
42759f1e | 937 | |
66f97d31 | 938 | return doms; |
42759f1e ZD |
939 | } |
940 | ||
438c239d | 941 | /* Returns the list of basic blocks including BB dominated by BB, in the |
cad9aa15 MK |
942 | direction DIR up to DEPTH in the dominator tree. The DEPTH of zero will |
943 | produce a vector containing all dominated blocks. The vector will be sorted | |
944 | in preorder. */ | |
438c239d | 945 | |
53c55d32 | 946 | auto_vec<basic_block> |
cad9aa15 | 947 | get_dominated_to_depth (enum cdi_direction dir, basic_block bb, int depth) |
438c239d | 948 | { |
53c55d32 | 949 | auto_vec<basic_block> bbs; |
438c239d | 950 | unsigned i; |
cad9aa15 | 951 | unsigned next_level_start; |
438c239d RG |
952 | |
953 | i = 0; | |
9771b263 DN |
954 | bbs.safe_push (bb); |
955 | next_level_start = 1; /* = bbs.length (); */ | |
438c239d RG |
956 | |
957 | do | |
958 | { | |
959 | basic_block son; | |
960 | ||
9771b263 | 961 | bb = bbs[i++]; |
438c239d RG |
962 | for (son = first_dom_son (dir, bb); |
963 | son; | |
964 | son = next_dom_son (dir, son)) | |
9771b263 | 965 | bbs.safe_push (son); |
cad9aa15 MK |
966 | |
967 | if (i == next_level_start && --depth) | |
9771b263 | 968 | next_level_start = bbs.length (); |
438c239d | 969 | } |
cad9aa15 | 970 | while (i < next_level_start); |
438c239d RG |
971 | |
972 | return bbs; | |
973 | } | |
974 | ||
cad9aa15 MK |
975 | /* Returns the list of basic blocks including BB dominated by BB, in the |
976 | direction DIR. The vector will be sorted in preorder. */ | |
977 | ||
53c55d32 | 978 | auto_vec<basic_block> |
cad9aa15 MK |
979 | get_all_dominated_blocks (enum cdi_direction dir, basic_block bb) |
980 | { | |
981 | return get_dominated_to_depth (dir, bb, 0); | |
982 | } | |
983 | ||
355be0dc JH |
984 | /* Redirect all edges pointing to BB to TO. */ |
985 | void | |
d47cc544 SB |
986 | redirect_immediate_dominators (enum cdi_direction dir, basic_block bb, |
987 | basic_block to) | |
355be0dc | 988 | { |
2b28c07a JC |
989 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
990 | struct et_node *bb_node, *to_node, *son; | |
b8698a0f | 991 | |
2b28c07a JC |
992 | bb_node = bb->dom[dir_index]; |
993 | to_node = to->dom[dir_index]; | |
d47cc544 | 994 | |
2ba31c05 | 995 | gcc_checking_assert (dom_computed[dir_index]); |
355be0dc | 996 | |
d47cc544 SB |
997 | if (!bb_node->son) |
998 | return; | |
999 | ||
1000 | while (bb_node->son) | |
355be0dc | 1001 | { |
d47cc544 SB |
1002 | son = bb_node->son; |
1003 | ||
1004 | et_split (son); | |
1005 | et_set_father (son, to_node); | |
355be0dc | 1006 | } |
d47cc544 | 1007 | |
2b28c07a JC |
1008 | if (dom_computed[dir_index] == DOM_OK) |
1009 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
1010 | } |
1011 | ||
1012 | /* Find first basic block in the tree dominating both BB1 and BB2. */ | |
1013 | basic_block | |
d47cc544 | 1014 | nearest_common_dominator (enum cdi_direction dir, basic_block bb1, basic_block bb2) |
355be0dc | 1015 | { |
2b28c07a JC |
1016 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1017 | ||
2ba31c05 | 1018 | gcc_checking_assert (dom_computed[dir_index]); |
d47cc544 | 1019 | |
355be0dc JH |
1020 | if (!bb1) |
1021 | return bb2; | |
1022 | if (!bb2) | |
1023 | return bb1; | |
d47cc544 | 1024 | |
f883e0a7 | 1025 | return (basic_block) et_nca (bb1->dom[dir_index], bb2->dom[dir_index])->data; |
355be0dc JH |
1026 | } |
1027 | ||
0bca51f0 DN |
1028 | |
1029 | /* Find the nearest common dominator for the basic blocks in BLOCKS, | |
1030 | using dominance direction DIR. */ | |
1031 | ||
1032 | basic_block | |
1033 | nearest_common_dominator_for_set (enum cdi_direction dir, bitmap blocks) | |
1034 | { | |
1035 | unsigned i, first; | |
1036 | bitmap_iterator bi; | |
1037 | basic_block dom; | |
b8698a0f | 1038 | |
0bca51f0 | 1039 | first = bitmap_first_set_bit (blocks); |
06e28de2 | 1040 | dom = BASIC_BLOCK_FOR_FN (cfun, first); |
0bca51f0 | 1041 | EXECUTE_IF_SET_IN_BITMAP (blocks, 0, i, bi) |
06e28de2 DM |
1042 | if (dom != BASIC_BLOCK_FOR_FN (cfun, i)) |
1043 | dom = nearest_common_dominator (dir, dom, BASIC_BLOCK_FOR_FN (cfun, i)); | |
0bca51f0 DN |
1044 | |
1045 | return dom; | |
1046 | } | |
1047 | ||
b629276a DB |
1048 | /* Given a dominator tree, we can determine whether one thing |
1049 | dominates another in constant time by using two DFS numbers: | |
1050 | ||
1051 | 1. The number for when we visit a node on the way down the tree | |
1052 | 2. The number for when we visit a node on the way back up the tree | |
1053 | ||
1054 | You can view these as bounds for the range of dfs numbers the | |
1055 | nodes in the subtree of the dominator tree rooted at that node | |
1056 | will contain. | |
b8698a0f | 1057 | |
b629276a DB |
1058 | The dominator tree is always a simple acyclic tree, so there are |
1059 | only three possible relations two nodes in the dominator tree have | |
1060 | to each other: | |
b8698a0f | 1061 | |
b629276a DB |
1062 | 1. Node A is above Node B (and thus, Node A dominates node B) |
1063 | ||
1064 | A | |
1065 | | | |
1066 | C | |
1067 | / \ | |
1068 | B D | |
1069 | ||
1070 | ||
1071 | In the above case, DFS_Number_In of A will be <= DFS_Number_In of | |
1072 | B, and DFS_Number_Out of A will be >= DFS_Number_Out of B. This is | |
1073 | because we must hit A in the dominator tree *before* B on the walk | |
1074 | down, and we will hit A *after* B on the walk back up | |
b8698a0f | 1075 | |
d8701f02 | 1076 | 2. Node A is below node B (and thus, node B dominates node A) |
b8698a0f L |
1077 | |
1078 | ||
b629276a DB |
1079 | B |
1080 | | | |
1081 | A | |
1082 | / \ | |
1083 | C D | |
1084 | ||
1085 | In the above case, DFS_Number_In of A will be >= DFS_Number_In of | |
1086 | B, and DFS_Number_Out of A will be <= DFS_Number_Out of B. | |
b8698a0f | 1087 | |
b629276a DB |
1088 | This is because we must hit A in the dominator tree *after* B on |
1089 | the walk down, and we will hit A *before* B on the walk back up | |
b8698a0f | 1090 | |
b629276a DB |
1091 | 3. Node A and B are siblings (and thus, neither dominates the other) |
1092 | ||
1093 | C | |
1094 | | | |
1095 | D | |
1096 | / \ | |
1097 | A B | |
1098 | ||
1099 | In the above case, DFS_Number_In of A will *always* be <= | |
1100 | DFS_Number_In of B, and DFS_Number_Out of A will *always* be <= | |
1101 | DFS_Number_Out of B. This is because we will always finish the dfs | |
1102 | walk of one of the subtrees before the other, and thus, the dfs | |
1103 | numbers for one subtree can't intersect with the range of dfs | |
1104 | numbers for the other subtree. If you swap A and B's position in | |
1105 | the dominator tree, the comparison changes direction, but the point | |
1106 | is that both comparisons will always go the same way if there is no | |
1107 | dominance relationship. | |
1108 | ||
1109 | Thus, it is sufficient to write | |
1110 | ||
1111 | A_Dominates_B (node A, node B) | |
1112 | { | |
b8698a0f | 1113 | return DFS_Number_In(A) <= DFS_Number_In(B) |
b629276a DB |
1114 | && DFS_Number_Out (A) >= DFS_Number_Out(B); |
1115 | } | |
1116 | ||
1117 | A_Dominated_by_B (node A, node B) | |
1118 | { | |
048f1a9c | 1119 | return DFS_Number_In(A) >= DFS_Number_In(B) |
b629276a DB |
1120 | && DFS_Number_Out (A) <= DFS_Number_Out(B); |
1121 | } */ | |
0bca51f0 | 1122 | |
355be0dc JH |
1123 | /* Return TRUE in case BB1 is dominated by BB2. */ |
1124 | bool | |
ed7a4b4b | 1125 | dominated_by_p (enum cdi_direction dir, const_basic_block bb1, const_basic_block bb2) |
b8698a0f | 1126 | { |
2b28c07a JC |
1127 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1128 | struct et_node *n1 = bb1->dom[dir_index], *n2 = bb2->dom[dir_index]; | |
b8698a0f | 1129 | |
2ba31c05 | 1130 | gcc_checking_assert (dom_computed[dir_index]); |
d47cc544 | 1131 | |
2b28c07a | 1132 | if (dom_computed[dir_index] == DOM_OK) |
d47cc544 | 1133 | return (n1->dfs_num_in >= n2->dfs_num_in |
6de9cd9a | 1134 | && n1->dfs_num_out <= n2->dfs_num_out); |
d47cc544 SB |
1135 | |
1136 | return et_below (n1, n2); | |
355be0dc JH |
1137 | } |
1138 | ||
f074ff6c ZD |
1139 | /* Returns the entry dfs number for basic block BB, in the direction DIR. */ |
1140 | ||
1141 | unsigned | |
1142 | bb_dom_dfs_in (enum cdi_direction dir, basic_block bb) | |
1143 | { | |
2b28c07a JC |
1144 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1145 | struct et_node *n = bb->dom[dir_index]; | |
f074ff6c | 1146 | |
2ba31c05 | 1147 | gcc_checking_assert (dom_computed[dir_index] == DOM_OK); |
f074ff6c ZD |
1148 | return n->dfs_num_in; |
1149 | } | |
1150 | ||
1151 | /* Returns the exit dfs number for basic block BB, in the direction DIR. */ | |
1152 | ||
1153 | unsigned | |
1154 | bb_dom_dfs_out (enum cdi_direction dir, basic_block bb) | |
1155 | { | |
2b28c07a JC |
1156 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1157 | struct et_node *n = bb->dom[dir_index]; | |
f074ff6c | 1158 | |
2ba31c05 | 1159 | gcc_checking_assert (dom_computed[dir_index] == DOM_OK); |
f074ff6c ZD |
1160 | return n->dfs_num_out; |
1161 | } | |
1162 | ||
355be0dc | 1163 | /* Verify invariants of dominator structure. */ |
24e47c76 | 1164 | DEBUG_FUNCTION void |
2321dd91 | 1165 | verify_dominators (cdi_direction dir) |
355be0dc | 1166 | { |
fce22de5 | 1167 | gcc_assert (dom_info_available_p (dir)); |
d47cc544 | 1168 | |
2321dd91 MM |
1169 | dom_info di (cfun, dir); |
1170 | di.calc_dfs_tree (); | |
1171 | di.calc_idoms (); | |
1fc3998d | 1172 | |
2321dd91 MM |
1173 | bool err = false; |
1174 | basic_block bb; | |
11cd3bed | 1175 | FOR_EACH_BB_FN (bb, cfun) |
355be0dc | 1176 | { |
2321dd91 | 1177 | basic_block imm_bb = get_immediate_dominator (dir, bb); |
1fc3998d | 1178 | if (!imm_bb) |
f8032688 | 1179 | { |
66f97d31 | 1180 | error ("dominator of %d status unknown", bb->index); |
2321dd91 | 1181 | err = true; |
bcfbf257 | 1182 | continue; |
355be0dc | 1183 | } |
66f97d31 | 1184 | |
2321dd91 | 1185 | basic_block imm_bb_correct = di.get_idom (bb); |
1fc3998d | 1186 | if (imm_bb != imm_bb_correct) |
e7bd94cc | 1187 | { |
66f97d31 | 1188 | error ("dominator of %d should be %d, not %d", |
1fc3998d | 1189 | bb->index, imm_bb_correct->index, imm_bb->index); |
2321dd91 | 1190 | err = true; |
e7bd94cc ZD |
1191 | } |
1192 | } | |
1193 | ||
ced3f397 | 1194 | gcc_assert (!err); |
355be0dc JH |
1195 | } |
1196 | ||
738ed977 ZD |
1197 | /* Determine immediate dominator (or postdominator, according to DIR) of BB, |
1198 | assuming that dominators of other blocks are correct. We also use it to | |
1199 | recompute the dominators in a restricted area, by iterating it until it | |
71cc389b | 1200 | reaches a fixed point. */ |
738ed977 | 1201 | |
355be0dc | 1202 | basic_block |
66f97d31 | 1203 | recompute_dominator (enum cdi_direction dir, basic_block bb) |
355be0dc | 1204 | { |
2b28c07a | 1205 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
738ed977 ZD |
1206 | basic_block dom_bb = NULL; |
1207 | edge e; | |
628f6a4e | 1208 | edge_iterator ei; |
355be0dc | 1209 | |
2ba31c05 | 1210 | gcc_checking_assert (dom_computed[dir_index]); |
d47cc544 | 1211 | |
738ed977 ZD |
1212 | if (dir == CDI_DOMINATORS) |
1213 | { | |
628f6a4e | 1214 | FOR_EACH_EDGE (e, ei, bb->preds) |
738ed977 ZD |
1215 | { |
1216 | if (!dominated_by_p (dir, e->src, bb)) | |
1217 | dom_bb = nearest_common_dominator (dir, dom_bb, e->src); | |
1218 | } | |
1219 | } | |
1220 | else | |
1221 | { | |
628f6a4e | 1222 | FOR_EACH_EDGE (e, ei, bb->succs) |
738ed977 ZD |
1223 | { |
1224 | if (!dominated_by_p (dir, e->dest, bb)) | |
1225 | dom_bb = nearest_common_dominator (dir, dom_bb, e->dest); | |
1226 | } | |
1227 | } | |
f8032688 | 1228 | |
738ed977 | 1229 | return dom_bb; |
355be0dc JH |
1230 | } |
1231 | ||
66f97d31 ZD |
1232 | /* Use simple heuristics (see iterate_fix_dominators) to determine dominators |
1233 | of BBS. We assume that all the immediate dominators except for those of the | |
1234 | blocks in BBS are correct. If CONSERVATIVE is true, we also assume that the | |
1235 | currently recorded immediate dominators of blocks in BBS really dominate the | |
1236 | blocks. The basic blocks for that we determine the dominator are removed | |
1237 | from BBS. */ | |
1238 | ||
1239 | static void | |
a3d3e8c3 | 1240 | prune_bbs_to_update_dominators (vec<basic_block> &bbs, |
66f97d31 ZD |
1241 | bool conservative) |
1242 | { | |
1243 | unsigned i; | |
1244 | bool single; | |
1245 | basic_block bb, dom = NULL; | |
1246 | edge_iterator ei; | |
1247 | edge e; | |
1248 | ||
9771b263 | 1249 | for (i = 0; bbs.iterate (i, &bb);) |
66f97d31 | 1250 | { |
fefa31b5 | 1251 | if (bb == ENTRY_BLOCK_PTR_FOR_FN (cfun)) |
66f97d31 ZD |
1252 | goto succeed; |
1253 | ||
1254 | if (single_pred_p (bb)) | |
1255 | { | |
1256 | set_immediate_dominator (CDI_DOMINATORS, bb, single_pred (bb)); | |
1257 | goto succeed; | |
1258 | } | |
1259 | ||
1260 | if (!conservative) | |
1261 | goto fail; | |
1262 | ||
1263 | single = true; | |
1264 | dom = NULL; | |
1265 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1266 | { | |
1267 | if (dominated_by_p (CDI_DOMINATORS, e->src, bb)) | |
1268 | continue; | |
1269 | ||
1270 | if (!dom) | |
1271 | dom = e->src; | |
1272 | else | |
1273 | { | |
1274 | single = false; | |
1275 | dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src); | |
1276 | } | |
1277 | } | |
1278 | ||
1279 | gcc_assert (dom != NULL); | |
1280 | if (single | |
1281 | || find_edge (dom, bb)) | |
1282 | { | |
1283 | set_immediate_dominator (CDI_DOMINATORS, bb, dom); | |
1284 | goto succeed; | |
1285 | } | |
1286 | ||
1287 | fail: | |
1288 | i++; | |
1289 | continue; | |
1290 | ||
1291 | succeed: | |
9771b263 | 1292 | bbs.unordered_remove (i); |
66f97d31 ZD |
1293 | } |
1294 | } | |
1295 | ||
1296 | /* Returns root of the dominance tree in the direction DIR that contains | |
1297 | BB. */ | |
1298 | ||
1299 | static basic_block | |
1300 | root_of_dom_tree (enum cdi_direction dir, basic_block bb) | |
1301 | { | |
f883e0a7 | 1302 | return (basic_block) et_root (bb->dom[dom_convert_dir_to_idx (dir)])->data; |
66f97d31 ZD |
1303 | } |
1304 | ||
1305 | /* See the comment in iterate_fix_dominators. Finds the immediate dominators | |
1306 | for the sons of Y, found using the SON and BROTHER arrays representing | |
1307 | the dominance tree of graph G. BBS maps the vertices of G to the basic | |
1308 | blocks. */ | |
1309 | ||
1310 | static void | |
9771b263 | 1311 | determine_dominators_for_sons (struct graph *g, vec<basic_block> bbs, |
66f97d31 ZD |
1312 | int y, int *son, int *brother) |
1313 | { | |
1314 | bitmap gprime; | |
1315 | int i, a, nc; | |
9771b263 | 1316 | vec<int> *sccs; |
66f97d31 ZD |
1317 | basic_block bb, dom, ybb; |
1318 | unsigned si; | |
1319 | edge e; | |
1320 | edge_iterator ei; | |
1321 | ||
1322 | if (son[y] == -1) | |
1323 | return; | |
9771b263 | 1324 | if (y == (int) bbs.length ()) |
fefa31b5 | 1325 | ybb = ENTRY_BLOCK_PTR_FOR_FN (cfun); |
66f97d31 | 1326 | else |
9771b263 | 1327 | ybb = bbs[y]; |
66f97d31 ZD |
1328 | |
1329 | if (brother[son[y]] == -1) | |
1330 | { | |
1331 | /* Handle the common case Y has just one son specially. */ | |
9771b263 | 1332 | bb = bbs[son[y]]; |
66f97d31 ZD |
1333 | set_immediate_dominator (CDI_DOMINATORS, bb, |
1334 | recompute_dominator (CDI_DOMINATORS, bb)); | |
1335 | identify_vertices (g, y, son[y]); | |
1336 | return; | |
1337 | } | |
1338 | ||
1339 | gprime = BITMAP_ALLOC (NULL); | |
1340 | for (a = son[y]; a != -1; a = brother[a]) | |
1341 | bitmap_set_bit (gprime, a); | |
1342 | ||
1343 | nc = graphds_scc (g, gprime); | |
1344 | BITMAP_FREE (gprime); | |
1345 | ||
9771b263 DN |
1346 | /* ??? Needed to work around the pre-processor confusion with |
1347 | using a multi-argument template type as macro argument. */ | |
1348 | typedef vec<int> vec_int_heap; | |
1349 | sccs = XCNEWVEC (vec_int_heap, nc); | |
66f97d31 | 1350 | for (a = son[y]; a != -1; a = brother[a]) |
9771b263 | 1351 | sccs[g->vertices[a].component].safe_push (a); |
66f97d31 ZD |
1352 | |
1353 | for (i = nc - 1; i >= 0; i--) | |
1354 | { | |
1355 | dom = NULL; | |
9771b263 | 1356 | FOR_EACH_VEC_ELT (sccs[i], si, a) |
66f97d31 | 1357 | { |
9771b263 | 1358 | bb = bbs[a]; |
66f97d31 ZD |
1359 | FOR_EACH_EDGE (e, ei, bb->preds) |
1360 | { | |
1361 | if (root_of_dom_tree (CDI_DOMINATORS, e->src) != ybb) | |
1362 | continue; | |
1363 | ||
1364 | dom = nearest_common_dominator (CDI_DOMINATORS, dom, e->src); | |
1365 | } | |
1366 | } | |
1367 | ||
1368 | gcc_assert (dom != NULL); | |
9771b263 | 1369 | FOR_EACH_VEC_ELT (sccs[i], si, a) |
66f97d31 | 1370 | { |
9771b263 | 1371 | bb = bbs[a]; |
66f97d31 ZD |
1372 | set_immediate_dominator (CDI_DOMINATORS, bb, dom); |
1373 | } | |
1374 | } | |
1375 | ||
1376 | for (i = 0; i < nc; i++) | |
9771b263 | 1377 | sccs[i].release (); |
66f97d31 ZD |
1378 | free (sccs); |
1379 | ||
1380 | for (a = son[y]; a != -1; a = brother[a]) | |
1381 | identify_vertices (g, y, a); | |
1382 | } | |
1383 | ||
1384 | /* Recompute dominance information for basic blocks in the set BBS. The | |
1385 | function assumes that the immediate dominators of all the other blocks | |
1386 | in CFG are correct, and that there are no unreachable blocks. | |
1387 | ||
1388 | If CONSERVATIVE is true, we additionally assume that all the ancestors of | |
1389 | a block of BBS in the current dominance tree dominate it. */ | |
1390 | ||
355be0dc | 1391 | void |
a3d3e8c3 | 1392 | iterate_fix_dominators (enum cdi_direction dir, vec<basic_block> &bbs, |
66f97d31 | 1393 | bool conservative) |
355be0dc | 1394 | { |
66f97d31 ZD |
1395 | unsigned i; |
1396 | basic_block bb, dom; | |
1397 | struct graph *g; | |
1398 | int n, y; | |
1399 | size_t dom_i; | |
1400 | edge e; | |
1401 | edge_iterator ei; | |
66f97d31 | 1402 | int *parent, *son, *brother; |
2b28c07a | 1403 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
355be0dc | 1404 | |
66f97d31 ZD |
1405 | /* We only support updating dominators. There are some problems with |
1406 | updating postdominators (need to add fake edges from infinite loops | |
1407 | and noreturn functions), and since we do not currently use | |
1408 | iterate_fix_dominators for postdominators, any attempt to handle these | |
1409 | problems would be unused, untested, and almost surely buggy. We keep | |
1410 | the DIR argument for consistency with the rest of the dominator analysis | |
1411 | interface. */ | |
2ba31c05 | 1412 | gcc_checking_assert (dir == CDI_DOMINATORS && dom_computed[dir_index]); |
d47cc544 | 1413 | |
66f97d31 ZD |
1414 | /* The algorithm we use takes inspiration from the following papers, although |
1415 | the details are quite different from any of them: | |
1416 | ||
1417 | [1] G. Ramalingam, T. Reps, An Incremental Algorithm for Maintaining the | |
1418 | Dominator Tree of a Reducible Flowgraph | |
1419 | [2] V. C. Sreedhar, G. R. Gao, Y.-F. Lee: Incremental computation of | |
1420 | dominator trees | |
1421 | [3] K. D. Cooper, T. J. Harvey and K. Kennedy: A Simple, Fast Dominance | |
1422 | Algorithm | |
1423 | ||
1424 | First, we use the following heuristics to decrease the size of the BBS | |
1425 | set: | |
1426 | a) if BB has a single predecessor, then its immediate dominator is this | |
1427 | predecessor | |
1428 | additionally, if CONSERVATIVE is true: | |
1429 | b) if all the predecessors of BB except for one (X) are dominated by BB, | |
1430 | then X is the immediate dominator of BB | |
1431 | c) if the nearest common ancestor of the predecessors of BB is X and | |
1432 | X -> BB is an edge in CFG, then X is the immediate dominator of BB | |
1433 | ||
1434 | Then, we need to establish the dominance relation among the basic blocks | |
1435 | in BBS. We split the dominance tree by removing the immediate dominator | |
0d52bcc1 | 1436 | edges from BBS, creating a forest F. We form a graph G whose vertices |
66f97d31 | 1437 | are BBS and ENTRY and X -> Y is an edge of G if there exists an edge |
0d52bcc1 | 1438 | X' -> Y in CFG such that X' belongs to the tree of the dominance forest |
66f97d31 ZD |
1439 | whose root is X. We then determine dominance tree of G. Note that |
1440 | for X, Y in BBS, X dominates Y in CFG if and only if X dominates Y in G. | |
1441 | In this step, we can use arbitrary algorithm to determine dominators. | |
1442 | We decided to prefer the algorithm [3] to the algorithm of | |
1443 | Lengauer and Tarjan, since the set BBS is usually small (rarely exceeding | |
1444 | 10 during gcc bootstrap), and [3] should perform better in this case. | |
1445 | ||
1446 | Finally, we need to determine the immediate dominators for the basic | |
1447 | blocks of BBS. If the immediate dominator of X in G is Y, then | |
1448 | the immediate dominator of X in CFG belongs to the tree of F rooted in | |
1449 | Y. We process the dominator tree T of G recursively, starting from leaves. | |
1450 | Suppose that X_1, X_2, ..., X_k are the sons of Y in T, and that the | |
1451 | subtrees of the dominance tree of CFG rooted in X_i are already correct. | |
1452 | Let G' be the subgraph of G induced by {X_1, X_2, ..., X_k}. We make | |
1453 | the following observations: | |
1454 | (i) the immediate dominator of all blocks in a strongly connected | |
1455 | component of G' is the same | |
1456 | (ii) if X has no predecessors in G', then the immediate dominator of X | |
1457 | is the nearest common ancestor of the predecessors of X in the | |
1458 | subtree of F rooted in Y | |
1459 | Therefore, it suffices to find the topological ordering of G', and | |
1460 | process the nodes X_i in this order using the rules (i) and (ii). | |
1461 | Then, we contract all the nodes X_i with Y in G, so that the further | |
1462 | steps work correctly. */ | |
1463 | ||
1464 | if (!conservative) | |
1465 | { | |
1466 | /* Split the tree now. If the idoms of blocks in BBS are not | |
1467 | conservatively correct, setting the dominators using the | |
1468 | heuristics in prune_bbs_to_update_dominators could | |
1469 | create cycles in the dominance "tree", and cause ICE. */ | |
9771b263 | 1470 | FOR_EACH_VEC_ELT (bbs, i, bb) |
66f97d31 ZD |
1471 | set_immediate_dominator (CDI_DOMINATORS, bb, NULL); |
1472 | } | |
1473 | ||
1474 | prune_bbs_to_update_dominators (bbs, conservative); | |
9771b263 | 1475 | n = bbs.length (); |
66f97d31 ZD |
1476 | |
1477 | if (n == 0) | |
1478 | return; | |
e7bd94cc | 1479 | |
66f97d31 | 1480 | if (n == 1) |
355be0dc | 1481 | { |
9771b263 | 1482 | bb = bbs[0]; |
66f97d31 ZD |
1483 | set_immediate_dominator (CDI_DOMINATORS, bb, |
1484 | recompute_dominator (CDI_DOMINATORS, bb)); | |
1485 | return; | |
1486 | } | |
1487 | ||
092cb01c RB |
1488 | timevar_push (TV_DOMINANCE); |
1489 | ||
66f97d31 | 1490 | /* Construct the graph G. */ |
1eb68d2d | 1491 | hash_map<basic_block, int> map (251); |
9771b263 | 1492 | FOR_EACH_VEC_ELT (bbs, i, bb) |
66f97d31 ZD |
1493 | { |
1494 | /* If the dominance tree is conservatively correct, split it now. */ | |
1495 | if (conservative) | |
1496 | set_immediate_dominator (CDI_DOMINATORS, bb, NULL); | |
1eb68d2d | 1497 | map.put (bb, i); |
66f97d31 | 1498 | } |
1eb68d2d | 1499 | map.put (ENTRY_BLOCK_PTR_FOR_FN (cfun), n); |
66f97d31 ZD |
1500 | |
1501 | g = new_graph (n + 1); | |
1502 | for (y = 0; y < g->n_vertices; y++) | |
1503 | g->vertices[y].data = BITMAP_ALLOC (NULL); | |
9771b263 | 1504 | FOR_EACH_VEC_ELT (bbs, i, bb) |
66f97d31 ZD |
1505 | { |
1506 | FOR_EACH_EDGE (e, ei, bb->preds) | |
355be0dc | 1507 | { |
66f97d31 ZD |
1508 | dom = root_of_dom_tree (CDI_DOMINATORS, e->src); |
1509 | if (dom == bb) | |
1510 | continue; | |
1511 | ||
1eb68d2d | 1512 | dom_i = *map.get (dom); |
66f97d31 ZD |
1513 | |
1514 | /* Do not include parallel edges to G. */ | |
fcaa4ca4 | 1515 | if (!bitmap_set_bit ((bitmap) g->vertices[dom_i].data, i)) |
66f97d31 ZD |
1516 | continue; |
1517 | ||
66f97d31 | 1518 | add_edge (g, dom_i, i); |
f8032688 MM |
1519 | } |
1520 | } | |
66f97d31 ZD |
1521 | for (y = 0; y < g->n_vertices; y++) |
1522 | BITMAP_FREE (g->vertices[y].data); | |
66f97d31 ZD |
1523 | |
1524 | /* Find the dominator tree of G. */ | |
1525 | son = XNEWVEC (int, n + 1); | |
1526 | brother = XNEWVEC (int, n + 1); | |
1527 | parent = XNEWVEC (int, n + 1); | |
1528 | graphds_domtree (g, n, parent, son, brother); | |
1529 | ||
1530 | /* Finally, traverse the tree and find the immediate dominators. */ | |
1531 | for (y = n; son[y] != -1; y = son[y]) | |
1532 | continue; | |
1533 | while (y != -1) | |
1534 | { | |
1535 | determine_dominators_for_sons (g, bbs, y, son, brother); | |
1536 | ||
1537 | if (brother[y] != -1) | |
1538 | { | |
1539 | y = brother[y]; | |
1540 | while (son[y] != -1) | |
1541 | y = son[y]; | |
1542 | } | |
1543 | else | |
1544 | y = parent[y]; | |
1545 | } | |
1546 | ||
1547 | free (son); | |
1548 | free (brother); | |
1549 | free (parent); | |
e7bd94cc | 1550 | |
66f97d31 | 1551 | free_graph (g); |
092cb01c RB |
1552 | |
1553 | timevar_pop (TV_DOMINANCE); | |
355be0dc | 1554 | } |
f8032688 | 1555 | |
355be0dc | 1556 | void |
d47cc544 | 1557 | add_to_dominance_info (enum cdi_direction dir, basic_block bb) |
355be0dc | 1558 | { |
2b28c07a JC |
1559 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1560 | ||
2ba31c05 | 1561 | gcc_checking_assert (dom_computed[dir_index] && !bb->dom[dir_index]); |
d47cc544 | 1562 | |
2b28c07a | 1563 | n_bbs_in_dom_tree[dir_index]++; |
b8698a0f | 1564 | |
2b28c07a | 1565 | bb->dom[dir_index] = et_new_tree (bb); |
d47cc544 | 1566 | |
2b28c07a JC |
1567 | if (dom_computed[dir_index] == DOM_OK) |
1568 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
355be0dc JH |
1569 | } |
1570 | ||
1571 | void | |
d47cc544 SB |
1572 | delete_from_dominance_info (enum cdi_direction dir, basic_block bb) |
1573 | { | |
2b28c07a | 1574 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
d47cc544 | 1575 | |
2ba31c05 | 1576 | gcc_checking_assert (dom_computed[dir_index]); |
d47cc544 | 1577 | |
2b28c07a JC |
1578 | et_free_tree (bb->dom[dir_index]); |
1579 | bb->dom[dir_index] = NULL; | |
1580 | n_bbs_in_dom_tree[dir_index]--; | |
1581 | ||
1582 | if (dom_computed[dir_index] == DOM_OK) | |
1583 | dom_computed[dir_index] = DOM_NO_FAST_QUERY; | |
d47cc544 SB |
1584 | } |
1585 | ||
1586 | /* Returns the first son of BB in the dominator or postdominator tree | |
1587 | as determined by DIR. */ | |
1588 | ||
1589 | basic_block | |
1590 | first_dom_son (enum cdi_direction dir, basic_block bb) | |
355be0dc | 1591 | { |
2b28c07a JC |
1592 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1593 | struct et_node *son = bb->dom[dir_index]->son; | |
d47cc544 | 1594 | |
f883e0a7 | 1595 | return (basic_block) (son ? son->data : NULL); |
d47cc544 SB |
1596 | } |
1597 | ||
1598 | /* Returns the next dominance son after BB in the dominator or postdominator | |
1599 | tree as determined by DIR, or NULL if it was the last one. */ | |
1600 | ||
1601 | basic_block | |
1602 | next_dom_son (enum cdi_direction dir, basic_block bb) | |
1603 | { | |
2b28c07a JC |
1604 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
1605 | struct et_node *next = bb->dom[dir_index]->right; | |
d47cc544 | 1606 | |
f883e0a7 | 1607 | return (basic_block) (next->father->son == next ? NULL : next->data); |
355be0dc JH |
1608 | } |
1609 | ||
2b28c07a JC |
1610 | /* Return dominance availability for dominance info DIR. */ |
1611 | ||
1612 | enum dom_state | |
e3f613cb | 1613 | dom_info_state (function *fn, enum cdi_direction dir) |
2b28c07a | 1614 | { |
e3f613cb RB |
1615 | if (!fn->cfg) |
1616 | return DOM_NONE; | |
1617 | ||
2b28c07a | 1618 | unsigned int dir_index = dom_convert_dir_to_idx (dir); |
e3f613cb RB |
1619 | return fn->cfg->x_dom_computed[dir_index]; |
1620 | } | |
2b28c07a | 1621 | |
e3f613cb RB |
1622 | enum dom_state |
1623 | dom_info_state (enum cdi_direction dir) | |
1624 | { | |
1625 | return dom_info_state (cfun, dir); | |
2b28c07a JC |
1626 | } |
1627 | ||
1628 | /* Set the dominance availability for dominance info DIR to NEW_STATE. */ | |
1629 | ||
1630 | void | |
1631 | set_dom_info_availability (enum cdi_direction dir, enum dom_state new_state) | |
1632 | { | |
1633 | unsigned int dir_index = dom_convert_dir_to_idx (dir); | |
1634 | ||
1635 | dom_computed[dir_index] = new_state; | |
1636 | } | |
1637 | ||
fce22de5 ZD |
1638 | /* Returns true if dominance information for direction DIR is available. */ |
1639 | ||
1640 | bool | |
e3f613cb | 1641 | dom_info_available_p (function *fn, enum cdi_direction dir) |
fce22de5 | 1642 | { |
e3f613cb RB |
1643 | return dom_info_state (fn, dir) != DOM_NONE; |
1644 | } | |
2b28c07a | 1645 | |
e3f613cb RB |
1646 | bool |
1647 | dom_info_available_p (enum cdi_direction dir) | |
1648 | { | |
1649 | return dom_info_available_p (cfun, dir); | |
fce22de5 ZD |
1650 | } |
1651 | ||
24e47c76 | 1652 | DEBUG_FUNCTION void |
d47cc544 | 1653 | debug_dominance_info (enum cdi_direction dir) |
355be0dc JH |
1654 | { |
1655 | basic_block bb, bb2; | |
11cd3bed | 1656 | FOR_EACH_BB_FN (bb, cfun) |
d47cc544 | 1657 | if ((bb2 = get_immediate_dominator (dir, bb))) |
355be0dc | 1658 | fprintf (stderr, "%i %i\n", bb->index, bb2->index); |
f8032688 | 1659 | } |
1fc3998d ZD |
1660 | |
1661 | /* Prints to stderr representation of the dominance tree (for direction DIR) | |
cea618ac | 1662 | rooted in ROOT, indented by INDENT tabulators. If INDENT_FIRST is false, |
1fc3998d ZD |
1663 | the first line of the output is not indented. */ |
1664 | ||
1665 | static void | |
1666 | debug_dominance_tree_1 (enum cdi_direction dir, basic_block root, | |
1667 | unsigned indent, bool indent_first) | |
1668 | { | |
1669 | basic_block son; | |
1670 | unsigned i; | |
1671 | bool first = true; | |
1672 | ||
1673 | if (indent_first) | |
1674 | for (i = 0; i < indent; i++) | |
1675 | fprintf (stderr, "\t"); | |
1676 | fprintf (stderr, "%d\t", root->index); | |
1677 | ||
1678 | for (son = first_dom_son (dir, root); | |
1679 | son; | |
1680 | son = next_dom_son (dir, son)) | |
1681 | { | |
1682 | debug_dominance_tree_1 (dir, son, indent + 1, !first); | |
1683 | first = false; | |
1684 | } | |
1685 | ||
1686 | if (first) | |
1687 | fprintf (stderr, "\n"); | |
1688 | } | |
1689 | ||
1690 | /* Prints to stderr representation of the dominance tree (for direction DIR) | |
1691 | rooted in ROOT. */ | |
1692 | ||
24e47c76 | 1693 | DEBUG_FUNCTION void |
1fc3998d ZD |
1694 | debug_dominance_tree (enum cdi_direction dir, basic_block root) |
1695 | { | |
1696 | debug_dominance_tree_1 (dir, root, 0, false); | |
1697 | } |