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a8046f60 | 1 | /* Thread edges through blocks and update the control flow and SSA graphs. |
d353bf18 | 2 | Copyright (C) 2004-2015 Free Software Foundation, Inc. |
a8046f60 | 3 | |
4 | This file is part of GCC. | |
5 | ||
6 | GCC is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8c4c00c1 | 8 | the Free Software Foundation; either version 3, or (at your option) |
a8046f60 | 9 | any later version. |
10 | ||
11 | GCC is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
a8046f60 | 19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
b20a8bb4 | 23 | #include "alias.h" |
9ef16211 | 24 | #include "backend.h" |
d040a5b0 | 25 | #include "cfghooks.h" |
a8046f60 | 26 | #include "tree.h" |
9ef16211 | 27 | #include "gimple.h" |
28 | #include "hard-reg-set.h" | |
29 | #include "ssa.h" | |
30 | #include "options.h" | |
b20a8bb4 | 31 | #include "fold-const.h" |
a8046f60 | 32 | #include "flags.h" |
94ea8568 | 33 | #include "cfganal.h" |
bc61cadb | 34 | #include "internal-fn.h" |
dcf1a1ec | 35 | #include "gimple-iterator.h" |
69ee5dbb | 36 | #include "tree-ssa.h" |
0c5b289a | 37 | #include "tree-ssa-threadupdate.h" |
b9ed1410 | 38 | #include "dumpfile.h" |
388d1fc1 | 39 | #include "cfgloop.h" |
a3724f9d | 40 | #include "dbgcnt.h" |
ab596744 | 41 | #include "tree-cfg.h" |
42 | #include "tree-pass.h" | |
a8046f60 | 43 | |
44 | /* Given a block B, update the CFG and SSA graph to reflect redirecting | |
45 | one or more in-edges to B to instead reach the destination of an | |
46 | out-edge from B while preserving any side effects in B. | |
47 | ||
0c6d8c36 | 48 | i.e., given A->B and B->C, change A->B to be A->C yet still preserve the |
a8046f60 | 49 | side effects of executing B. |
50 | ||
51 | 1. Make a copy of B (including its outgoing edges and statements). Call | |
52 | the copy B'. Note B' has no incoming edges or PHIs at this time. | |
53 | ||
54 | 2. Remove the control statement at the end of B' and all outgoing edges | |
55 | except B'->C. | |
56 | ||
57 | 3. Add a new argument to each PHI in C with the same value as the existing | |
58 | argument associated with edge B->C. Associate the new PHI arguments | |
59 | with the edge B'->C. | |
60 | ||
61 | 4. For each PHI in B, find or create a PHI in B' with an identical | |
7a635e9c | 62 | PHI_RESULT. Add an argument to the PHI in B' which has the same |
a8046f60 | 63 | value as the PHI in B associated with the edge A->B. Associate |
64 | the new argument in the PHI in B' with the edge A->B. | |
65 | ||
66 | 5. Change the edge A->B to A->B'. | |
67 | ||
68 | 5a. This automatically deletes any PHI arguments associated with the | |
69 | edge A->B in B. | |
70 | ||
71 | 5b. This automatically associates each new argument added in step 4 | |
72 | with the edge A->B'. | |
73 | ||
74 | 6. Repeat for other incoming edges into B. | |
75 | ||
76 | 7. Put the duplicated resources in B and all the B' blocks into SSA form. | |
77 | ||
78 | Note that block duplication can be minimized by first collecting the | |
f0b5f617 | 79 | set of unique destination blocks that the incoming edges should |
255a8494 | 80 | be threaded to. |
81 | ||
afe75331 | 82 | We reduce the number of edges and statements we create by not copying all |
83 | the outgoing edges and the control statement in step #1. We instead create | |
84 | a template block without the outgoing edges and duplicate the template. | |
a8046f60 | 85 | |
afe75331 | 86 | Another case this code handles is threading through a "joiner" block. In |
87 | this case, we do not know the destination of the joiner block, but one | |
88 | of the outgoing edges from the joiner block leads to a threadable path. This | |
89 | case largely works as outlined above, except the duplicate of the joiner | |
90 | block still contains a full set of outgoing edges and its control statement. | |
91 | We just redirect one of its outgoing edges to our jump threading path. */ | |
778182c1 | 92 | |
93 | ||
94 | /* Steps #5 and #6 of the above algorithm are best implemented by walking | |
95 | all the incoming edges which thread to the same destination edge at | |
96 | the same time. That avoids lots of table lookups to get information | |
97 | for the destination edge. | |
98 | ||
99 | To realize that implementation we create a list of incoming edges | |
100 | which thread to the same outgoing edge. Thus to implement steps | |
101 | #5 and #6 we traverse our hash table of outgoing edge information. | |
102 | For each entry we walk the list of incoming edges which thread to | |
103 | the current outgoing edge. */ | |
104 | ||
105 | struct el | |
106 | { | |
107 | edge e; | |
108 | struct el *next; | |
109 | }; | |
a8046f60 | 110 | |
111 | /* Main data structure recording information regarding B's duplicate | |
112 | blocks. */ | |
113 | ||
778182c1 | 114 | /* We need to efficiently record the unique thread destinations of this |
115 | block and specific information associated with those destinations. We | |
116 | may have many incoming edges threaded to the same outgoing edge. This | |
c5d4a10b | 117 | can be naturally implemented with a hash table. */ |
778182c1 | 118 | |
298e7f9a | 119 | struct redirection_data : free_ptr_hash<redirection_data> |
a8046f60 | 120 | { |
11af02d8 | 121 | /* We support wiring up two block duplicates in a jump threading path. |
122 | ||
123 | One is a normal block copy where we remove the control statement | |
124 | and wire up its single remaining outgoing edge to the thread path. | |
125 | ||
126 | The other is a joiner block where we leave the control statement | |
1b83778e | 127 | in place, but wire one of the outgoing edges to a thread path. |
11af02d8 | 128 | |
129 | In theory we could have multiple block duplicates in a jump | |
130 | threading path, but I haven't tried that. | |
131 | ||
132 | The duplicate blocks appear in this array in the same order in | |
133 | which they appear in the jump thread path. */ | |
134 | basic_block dup_blocks[2]; | |
a8046f60 | 135 | |
5fe6149c | 136 | /* The jump threading path. */ |
137 | vec<jump_thread_edge *> *path; | |
778182c1 | 138 | |
5fe6149c | 139 | /* A list of incoming edges which we want to thread to the |
140 | same path. */ | |
778182c1 | 141 | struct el *incoming_edges; |
494bbaae | 142 | |
143 | /* hash_table support. */ | |
9969c043 | 144 | static inline hashval_t hash (const redirection_data *); |
145 | static inline int equal (const redirection_data *, const redirection_data *); | |
a8046f60 | 146 | }; |
147 | ||
b93ba654 | 148 | /* Dump a jump threading path, including annotations about each |
149 | edge in the path. */ | |
150 | ||
151 | static void | |
152 | dump_jump_thread_path (FILE *dump_file, vec<jump_thread_edge *> path, | |
153 | bool registering) | |
154 | { | |
155 | fprintf (dump_file, | |
ded1c768 | 156 | " %s%s jump thread: (%d, %d) incoming edge; ", |
b93ba654 | 157 | (registering ? "Registering" : "Cancelling"), |
ded1c768 | 158 | (path[0]->type == EDGE_FSM_THREAD ? " FSM": ""), |
b93ba654 | 159 | path[0]->e->src->index, path[0]->e->dest->index); |
160 | ||
161 | for (unsigned int i = 1; i < path.length (); i++) | |
162 | { | |
163 | /* We can get paths with a NULL edge when the final destination | |
164 | of a jump thread turns out to be a constant address. We dump | |
165 | those paths when debugging, so we have to be prepared for that | |
166 | possibility here. */ | |
167 | if (path[i]->e == NULL) | |
168 | continue; | |
169 | ||
170 | if (path[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
171 | fprintf (dump_file, " (%d, %d) joiner; ", | |
172 | path[i]->e->src->index, path[i]->e->dest->index); | |
173 | if (path[i]->type == EDGE_COPY_SRC_BLOCK) | |
174 | fprintf (dump_file, " (%d, %d) normal;", | |
175 | path[i]->e->src->index, path[i]->e->dest->index); | |
176 | if (path[i]->type == EDGE_NO_COPY_SRC_BLOCK) | |
177 | fprintf (dump_file, " (%d, %d) nocopy;", | |
178 | path[i]->e->src->index, path[i]->e->dest->index); | |
c5baf1e1 | 179 | if (path[0]->type == EDGE_FSM_THREAD) |
180 | fprintf (dump_file, " (%d, %d) ", | |
181 | path[i]->e->src->index, path[i]->e->dest->index); | |
b93ba654 | 182 | } |
183 | fputc ('\n', dump_file); | |
184 | } | |
185 | ||
5fe6149c | 186 | /* Simple hashing function. For any given incoming edge E, we're going |
187 | to be most concerned with the final destination of its jump thread | |
188 | path. So hash on the block index of the final edge in the path. */ | |
189 | ||
494bbaae | 190 | inline hashval_t |
9969c043 | 191 | redirection_data::hash (const redirection_data *p) |
494bbaae | 192 | { |
5fe6149c | 193 | vec<jump_thread_edge *> *path = p->path; |
194 | return path->last ()->e->dest->index; | |
494bbaae | 195 | } |
196 | ||
5fe6149c | 197 | /* Given two hash table entries, return true if they have the same |
198 | jump threading path. */ | |
494bbaae | 199 | inline int |
9969c043 | 200 | redirection_data::equal (const redirection_data *p1, const redirection_data *p2) |
494bbaae | 201 | { |
5fe6149c | 202 | vec<jump_thread_edge *> *path1 = p1->path; |
203 | vec<jump_thread_edge *> *path2 = p2->path; | |
204 | ||
205 | if (path1->length () != path2->length ()) | |
206 | return false; | |
207 | ||
208 | for (unsigned int i = 1; i < path1->length (); i++) | |
209 | { | |
210 | if ((*path1)[i]->type != (*path2)[i]->type | |
211 | || (*path1)[i]->e != (*path2)[i]->e) | |
212 | return false; | |
213 | } | |
214 | ||
215 | return true; | |
494bbaae | 216 | } |
217 | ||
778182c1 | 218 | /* Data structure of information to pass to hash table traversal routines. */ |
2b15d2ba | 219 | struct ssa_local_info_t |
778182c1 | 220 | { |
221 | /* The current block we are working on. */ | |
222 | basic_block bb; | |
223 | ||
11af02d8 | 224 | /* We only create a template block for the first duplicated block in a |
225 | jump threading path as we may need many duplicates of that block. | |
226 | ||
227 | The second duplicate block in a path is specific to that path. Creating | |
228 | and sharing a template for that block is considerably more difficult. */ | |
778182c1 | 229 | basic_block template_block; |
388d1fc1 | 230 | |
231 | /* TRUE if we thread one or more jumps, FALSE otherwise. */ | |
232 | bool jumps_threaded; | |
30e432bb | 233 | |
234 | /* Blocks duplicated for the thread. */ | |
235 | bitmap duplicate_blocks; | |
778182c1 | 236 | }; |
a3d0fd80 | 237 | |
3cebc9d2 | 238 | /* Passes which use the jump threading code register jump threading |
239 | opportunities as they are discovered. We keep the registered | |
240 | jump threading opportunities in this vector as edge pairs | |
241 | (original_edge, target_edge). */ | |
f2981b08 | 242 | static vec<vec<jump_thread_edge *> *> paths; |
3cebc9d2 | 243 | |
eb31063a | 244 | /* When we start updating the CFG for threading, data necessary for jump |
245 | threading is attached to the AUX field for the incoming edge. Use these | |
246 | macros to access the underlying structure attached to the AUX field. */ | |
f2981b08 | 247 | #define THREAD_PATH(E) ((vec<jump_thread_edge *> *)(E)->aux) |
3cebc9d2 | 248 | |
5236b8bb | 249 | /* Jump threading statistics. */ |
250 | ||
251 | struct thread_stats_d | |
252 | { | |
253 | unsigned long num_threaded_edges; | |
254 | }; | |
255 | ||
256 | struct thread_stats_d thread_stats; | |
257 | ||
258 | ||
f582bb6c | 259 | /* Remove the last statement in block BB if it is a control statement |
260 | Also remove all outgoing edges except the edge which reaches DEST_BB. | |
261 | If DEST_BB is NULL, then remove all outgoing edges. */ | |
a8046f60 | 262 | |
f1344f45 | 263 | void |
f582bb6c | 264 | remove_ctrl_stmt_and_useless_edges (basic_block bb, basic_block dest_bb) |
a8046f60 | 265 | { |
75a70cf9 | 266 | gimple_stmt_iterator gsi; |
cd665a06 | 267 | edge e; |
268 | edge_iterator ei; | |
a8046f60 | 269 | |
75a70cf9 | 270 | gsi = gsi_last_bb (bb); |
a8046f60 | 271 | |
f582bb6c | 272 | /* If the duplicate ends with a control statement, then remove it. |
a8046f60 | 273 | |
f582bb6c | 274 | Note that if we are duplicating the template block rather than the |
275 | original basic block, then the duplicate might not have any real | |
276 | statements in it. */ | |
75a70cf9 | 277 | if (!gsi_end_p (gsi) |
278 | && gsi_stmt (gsi) | |
279 | && (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND | |
280 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_GOTO | |
281 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_SWITCH)) | |
282 | gsi_remove (&gsi, true); | |
a8046f60 | 283 | |
cd665a06 | 284 | for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) |
a8046f60 | 285 | { |
a8046f60 | 286 | if (e->dest != dest_bb) |
0891994d | 287 | remove_edge (e); |
cd665a06 | 288 | else |
289 | ei_next (&ei); | |
a8046f60 | 290 | } |
a8046f60 | 291 | } |
292 | ||
11af02d8 | 293 | /* Create a duplicate of BB. Record the duplicate block in an array |
a7ee7309 | 294 | indexed by COUNT stored in RD. */ |
a8046f60 | 295 | |
296 | static void | |
11af02d8 | 297 | create_block_for_threading (basic_block bb, |
298 | struct redirection_data *rd, | |
30e432bb | 299 | unsigned int count, |
a7ee7309 | 300 | bitmap *duplicate_blocks) |
a8046f60 | 301 | { |
eb31063a | 302 | edge_iterator ei; |
303 | edge e; | |
304 | ||
a8046f60 | 305 | /* We can use the generic block duplication code and simply remove |
306 | the stuff we do not need. */ | |
11af02d8 | 307 | rd->dup_blocks[count] = duplicate_block (bb, NULL, NULL); |
a8046f60 | 308 | |
11af02d8 | 309 | FOR_EACH_EDGE (e, ei, rd->dup_blocks[count]->succs) |
eb31063a | 310 | e->aux = NULL; |
311 | ||
615dd397 | 312 | /* Zero out the profile, since the block is unreachable for now. */ |
11af02d8 | 313 | rd->dup_blocks[count]->frequency = 0; |
314 | rd->dup_blocks[count]->count = 0; | |
30e432bb | 315 | if (duplicate_blocks) |
316 | bitmap_set_bit (*duplicate_blocks, rd->dup_blocks[count]->index); | |
a8046f60 | 317 | } |
318 | ||
2b15d2ba | 319 | /* Main data structure to hold information for duplicates of BB. */ |
320 | ||
c1f445d2 | 321 | static hash_table<redirection_data> *redirection_data; |
2b15d2ba | 322 | |
778182c1 | 323 | /* Given an outgoing edge E lookup and return its entry in our hash table. |
324 | ||
325 | If INSERT is true, then we insert the entry into the hash table if | |
326 | it is not already present. INCOMING_EDGE is added to the list of incoming | |
327 | edges associated with E in the hash table. */ | |
328 | ||
329 | static struct redirection_data * | |
da81e0c5 | 330 | lookup_redirection_data (edge e, enum insert_option insert) |
778182c1 | 331 | { |
2b15d2ba | 332 | struct redirection_data **slot; |
778182c1 | 333 | struct redirection_data *elt; |
f2981b08 | 334 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
778182c1 | 335 | |
336 | /* Build a hash table element so we can see if E is already | |
337 | in the table. */ | |
4c36ffe6 | 338 | elt = XNEW (struct redirection_data); |
5fe6149c | 339 | elt->path = path; |
11af02d8 | 340 | elt->dup_blocks[0] = NULL; |
341 | elt->dup_blocks[1] = NULL; | |
778182c1 | 342 | elt->incoming_edges = NULL; |
343 | ||
c1f445d2 | 344 | slot = redirection_data->find_slot (elt, insert); |
778182c1 | 345 | |
346 | /* This will only happen if INSERT is false and the entry is not | |
347 | in the hash table. */ | |
348 | if (slot == NULL) | |
349 | { | |
350 | free (elt); | |
351 | return NULL; | |
352 | } | |
353 | ||
354 | /* This will only happen if E was not in the hash table and | |
355 | INSERT is true. */ | |
356 | if (*slot == NULL) | |
357 | { | |
2b15d2ba | 358 | *slot = elt; |
4c36ffe6 | 359 | elt->incoming_edges = XNEW (struct el); |
da81e0c5 | 360 | elt->incoming_edges->e = e; |
778182c1 | 361 | elt->incoming_edges->next = NULL; |
362 | return elt; | |
363 | } | |
364 | /* E was in the hash table. */ | |
365 | else | |
366 | { | |
367 | /* Free ELT as we do not need it anymore, we will extract the | |
368 | relevant entry from the hash table itself. */ | |
369 | free (elt); | |
370 | ||
371 | /* Get the entry stored in the hash table. */ | |
2b15d2ba | 372 | elt = *slot; |
778182c1 | 373 | |
374 | /* If insertion was requested, then we need to add INCOMING_EDGE | |
375 | to the list of incoming edges associated with E. */ | |
376 | if (insert) | |
377 | { | |
559685be | 378 | struct el *el = XNEW (struct el); |
778182c1 | 379 | el->next = elt->incoming_edges; |
da81e0c5 | 380 | el->e = e; |
778182c1 | 381 | elt->incoming_edges = el; |
382 | } | |
383 | ||
384 | return elt; | |
385 | } | |
386 | } | |
387 | ||
fc54aba7 | 388 | /* Similar to copy_phi_args, except that the PHI arg exists, it just |
389 | does not have a value associated with it. */ | |
390 | ||
391 | static void | |
392 | copy_phi_arg_into_existing_phi (edge src_e, edge tgt_e) | |
393 | { | |
394 | int src_idx = src_e->dest_idx; | |
395 | int tgt_idx = tgt_e->dest_idx; | |
396 | ||
397 | /* Iterate over each PHI in e->dest. */ | |
1a91d914 | 398 | for (gphi_iterator gsi = gsi_start_phis (src_e->dest), |
399 | gsi2 = gsi_start_phis (tgt_e->dest); | |
fc54aba7 | 400 | !gsi_end_p (gsi); |
401 | gsi_next (&gsi), gsi_next (&gsi2)) | |
402 | { | |
1a91d914 | 403 | gphi *src_phi = gsi.phi (); |
404 | gphi *dest_phi = gsi2.phi (); | |
fc54aba7 | 405 | tree val = gimple_phi_arg_def (src_phi, src_idx); |
406 | source_location locus = gimple_phi_arg_location (src_phi, src_idx); | |
407 | ||
408 | SET_PHI_ARG_DEF (dest_phi, tgt_idx, val); | |
409 | gimple_phi_arg_set_location (dest_phi, tgt_idx, locus); | |
410 | } | |
411 | } | |
412 | ||
1b83c31b | 413 | /* Given ssa_name DEF, backtrack jump threading PATH from node IDX |
414 | to see if it has constant value in a flow sensitive manner. Set | |
415 | LOCUS to location of the constant phi arg and return the value. | |
416 | Return DEF directly if either PATH or idx is ZERO. */ | |
417 | ||
418 | static tree | |
419 | get_value_locus_in_path (tree def, vec<jump_thread_edge *> *path, | |
420 | basic_block bb, int idx, source_location *locus) | |
421 | { | |
422 | tree arg; | |
1a91d914 | 423 | gphi *def_phi; |
1b83c31b | 424 | basic_block def_bb; |
425 | ||
426 | if (path == NULL || idx == 0) | |
427 | return def; | |
428 | ||
1a91d914 | 429 | def_phi = dyn_cast <gphi *> (SSA_NAME_DEF_STMT (def)); |
430 | if (!def_phi) | |
1b83c31b | 431 | return def; |
432 | ||
433 | def_bb = gimple_bb (def_phi); | |
434 | /* Don't propagate loop invariants into deeper loops. */ | |
435 | if (!def_bb || bb_loop_depth (def_bb) < bb_loop_depth (bb)) | |
436 | return def; | |
437 | ||
438 | /* Backtrack jump threading path from IDX to see if def has constant | |
439 | value. */ | |
440 | for (int j = idx - 1; j >= 0; j--) | |
441 | { | |
442 | edge e = (*path)[j]->e; | |
443 | if (e->dest == def_bb) | |
444 | { | |
445 | arg = gimple_phi_arg_def (def_phi, e->dest_idx); | |
446 | if (is_gimple_min_invariant (arg)) | |
447 | { | |
448 | *locus = gimple_phi_arg_location (def_phi, e->dest_idx); | |
449 | return arg; | |
450 | } | |
451 | break; | |
452 | } | |
453 | } | |
454 | ||
455 | return def; | |
456 | } | |
457 | ||
458 | /* For each PHI in BB, copy the argument associated with SRC_E to TGT_E. | |
459 | Try to backtrack jump threading PATH from node IDX to see if the arg | |
460 | has constant value, copy constant value instead of argument itself | |
461 | if yes. */ | |
da81e0c5 | 462 | |
463 | static void | |
1b83c31b | 464 | copy_phi_args (basic_block bb, edge src_e, edge tgt_e, |
465 | vec<jump_thread_edge *> *path, int idx) | |
da81e0c5 | 466 | { |
1a91d914 | 467 | gphi_iterator gsi; |
da81e0c5 | 468 | int src_indx = src_e->dest_idx; |
469 | ||
470 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
471 | { | |
1a91d914 | 472 | gphi *phi = gsi.phi (); |
1b83c31b | 473 | tree def = gimple_phi_arg_def (phi, src_indx); |
da81e0c5 | 474 | source_location locus = gimple_phi_arg_location (phi, src_indx); |
1b83c31b | 475 | |
476 | if (TREE_CODE (def) == SSA_NAME | |
477 | && !virtual_operand_p (gimple_phi_result (phi))) | |
478 | def = get_value_locus_in_path (def, path, bb, idx, &locus); | |
479 | ||
480 | add_phi_arg (phi, def, tgt_e, locus); | |
da81e0c5 | 481 | } |
482 | } | |
483 | ||
484 | /* We have recently made a copy of ORIG_BB, including its outgoing | |
485 | edges. The copy is NEW_BB. Every PHI node in every direct successor of | |
486 | ORIG_BB has a new argument associated with edge from NEW_BB to the | |
487 | successor. Initialize the PHI argument so that it is equal to the PHI | |
1b83c31b | 488 | argument associated with the edge from ORIG_BB to the successor. |
489 | PATH and IDX are used to check if the new PHI argument has constant | |
490 | value in a flow sensitive manner. */ | |
da81e0c5 | 491 | |
492 | static void | |
1b83c31b | 493 | update_destination_phis (basic_block orig_bb, basic_block new_bb, |
494 | vec<jump_thread_edge *> *path, int idx) | |
da81e0c5 | 495 | { |
496 | edge_iterator ei; | |
497 | edge e; | |
498 | ||
499 | FOR_EACH_EDGE (e, ei, orig_bb->succs) | |
500 | { | |
501 | edge e2 = find_edge (new_bb, e->dest); | |
1b83c31b | 502 | copy_phi_args (e->dest, e, e2, path, idx); |
da81e0c5 | 503 | } |
504 | } | |
505 | ||
778182c1 | 506 | /* Given a duplicate block and its single destination (both stored |
507 | in RD). Create an edge between the duplicate and its single | |
508 | destination. | |
509 | ||
510 | Add an additional argument to any PHI nodes at the single | |
1b83c31b | 511 | destination. IDX is the start node in jump threading path |
512 | we start to check to see if the new PHI argument has constant | |
513 | value along the jump threading path. */ | |
778182c1 | 514 | |
515 | static void | |
42b013bc | 516 | create_edge_and_update_destination_phis (struct redirection_data *rd, |
1b83c31b | 517 | basic_block bb, int idx) |
778182c1 | 518 | { |
5fe6149c | 519 | edge e = make_edge (bb, rd->path->last ()->e->dest, EDGE_FALLTHRU); |
778182c1 | 520 | |
f9614b84 | 521 | rescan_loop_exit (e, true, false); |
421e19dd | 522 | e->probability = REG_BR_PROB_BASE; |
42b013bc | 523 | e->count = bb->count; |
eb31063a | 524 | |
e63988cc | 525 | /* We used to copy the thread path here. That was added in 2007 |
526 | and dutifully updated through the representation changes in 2013. | |
527 | ||
528 | In 2013 we added code to thread from an interior node through | |
529 | the backedge to another interior node. That runs after the code | |
530 | to thread through loop headers from outside the loop. | |
531 | ||
532 | The latter may delete edges in the CFG, including those | |
533 | which appeared in the jump threading path we copied here. Thus | |
534 | we'd end up using a dangling pointer. | |
535 | ||
536 | After reviewing the 2007/2011 code, I can't see how anything | |
537 | depended on copying the AUX field and clearly copying the jump | |
538 | threading path is problematical due to embedded edge pointers. | |
539 | It has been removed. */ | |
540 | e->aux = NULL; | |
421e19dd | 541 | |
778182c1 | 542 | /* If there are any PHI nodes at the destination of the outgoing edge |
543 | from the duplicate block, then we will need to add a new argument | |
544 | to them. The argument should have the same value as the argument | |
545 | associated with the outgoing edge stored in RD. */ | |
1b83c31b | 546 | copy_phi_args (e->dest, rd->path->last ()->e, e, rd->path, idx); |
da81e0c5 | 547 | } |
548 | ||
fc54aba7 | 549 | /* Look through PATH beginning at START and return TRUE if there are |
550 | any additional blocks that need to be duplicated. Otherwise, | |
551 | return FALSE. */ | |
552 | static bool | |
553 | any_remaining_duplicated_blocks (vec<jump_thread_edge *> *path, | |
554 | unsigned int start) | |
555 | { | |
556 | for (unsigned int i = start + 1; i < path->length (); i++) | |
557 | { | |
558 | if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK | |
559 | || (*path)[i]->type == EDGE_COPY_SRC_BLOCK) | |
560 | return true; | |
561 | } | |
562 | return false; | |
563 | } | |
564 | ||
30e432bb | 565 | |
566 | /* Compute the amount of profile count/frequency coming into the jump threading | |
567 | path stored in RD that we are duplicating, returned in PATH_IN_COUNT_PTR and | |
568 | PATH_IN_FREQ_PTR, as well as the amount of counts flowing out of the | |
569 | duplicated path, returned in PATH_OUT_COUNT_PTR. LOCAL_INFO is used to | |
570 | identify blocks duplicated for jump threading, which have duplicated | |
571 | edges that need to be ignored in the analysis. Return true if path contains | |
572 | a joiner, false otherwise. | |
573 | ||
574 | In the non-joiner case, this is straightforward - all the counts/frequency | |
575 | flowing into the jump threading path should flow through the duplicated | |
576 | block and out of the duplicated path. | |
577 | ||
578 | In the joiner case, it is very tricky. Some of the counts flowing into | |
579 | the original path go offpath at the joiner. The problem is that while | |
580 | we know how much total count goes off-path in the original control flow, | |
581 | we don't know how many of the counts corresponding to just the jump | |
582 | threading path go offpath at the joiner. | |
583 | ||
584 | For example, assume we have the following control flow and identified | |
585 | jump threading paths: | |
586 | ||
9943b198 | 587 | A B C |
588 | \ | / | |
589 | Ea \ |Eb / Ec | |
590 | \ | / | |
591 | v v v | |
592 | J <-- Joiner | |
593 | / \ | |
594 | Eoff/ \Eon | |
595 | / \ | |
596 | v v | |
597 | Soff Son <--- Normal | |
598 | /\ | |
599 | Ed/ \ Ee | |
600 | / \ | |
601 | v v | |
602 | D E | |
603 | ||
604 | Jump threading paths: A -> J -> Son -> D (path 1) | |
605 | C -> J -> Son -> E (path 2) | |
30e432bb | 606 | |
607 | Note that the control flow could be more complicated: | |
608 | - Each jump threading path may have more than one incoming edge. I.e. A and | |
609 | Ea could represent multiple incoming blocks/edges that are included in | |
610 | path 1. | |
611 | - There could be EDGE_NO_COPY_SRC_BLOCK edges after the joiner (either | |
612 | before or after the "normal" copy block). These are not duplicated onto | |
613 | the jump threading path, as they are single-successor. | |
614 | - Any of the blocks along the path may have other incoming edges that | |
615 | are not part of any jump threading path, but add profile counts along | |
616 | the path. | |
617 | ||
618 | In the aboe example, after all jump threading is complete, we will | |
619 | end up with the following control flow: | |
620 | ||
9943b198 | 621 | A B C |
622 | | | | | |
623 | Ea| |Eb |Ec | |
624 | | | | | |
625 | v v v | |
626 | Ja J Jc | |
627 | / \ / \Eon' / \ | |
628 | Eona/ \ ---/---\-------- \Eonc | |
629 | / \ / / \ \ | |
630 | v v v v v | |
631 | Sona Soff Son Sonc | |
632 | \ /\ / | |
633 | \___________ / \ _____/ | |
634 | \ / \/ | |
635 | vv v | |
636 | D E | |
30e432bb | 637 | |
638 | The main issue to notice here is that when we are processing path 1 | |
639 | (A->J->Son->D) we need to figure out the outgoing edge weights to | |
640 | the duplicated edges Ja->Sona and Ja->Soff, while ensuring that the | |
641 | sum of the incoming weights to D remain Ed. The problem with simply | |
642 | assuming that Ja (and Jc when processing path 2) has the same outgoing | |
643 | probabilities to its successors as the original block J, is that after | |
644 | all paths are processed and other edges/counts removed (e.g. none | |
645 | of Ec will reach D after processing path 2), we may end up with not | |
646 | enough count flowing along duplicated edge Sona->D. | |
647 | ||
648 | Therefore, in the case of a joiner, we keep track of all counts | |
649 | coming in along the current path, as well as from predecessors not | |
650 | on any jump threading path (Eb in the above example). While we | |
651 | first assume that the duplicated Eona for Ja->Sona has the same | |
652 | probability as the original, we later compensate for other jump | |
653 | threading paths that may eliminate edges. We do that by keep track | |
654 | of all counts coming into the original path that are not in a jump | |
655 | thread (Eb in the above example, but as noted earlier, there could | |
656 | be other predecessors incoming to the path at various points, such | |
657 | as at Son). Call this cumulative non-path count coming into the path | |
658 | before D as Enonpath. We then ensure that the count from Sona->D is as at | |
659 | least as big as (Ed - Enonpath), but no bigger than the minimum | |
660 | weight along the jump threading path. The probabilities of both the | |
661 | original and duplicated joiner block J and Ja will be adjusted | |
662 | accordingly after the updates. */ | |
663 | ||
664 | static bool | |
665 | compute_path_counts (struct redirection_data *rd, | |
9943b198 | 666 | ssa_local_info_t *local_info, |
667 | gcov_type *path_in_count_ptr, | |
668 | gcov_type *path_out_count_ptr, | |
669 | int *path_in_freq_ptr) | |
30e432bb | 670 | { |
671 | edge e = rd->incoming_edges->e; | |
672 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
673 | edge elast = path->last ()->e; | |
674 | gcov_type nonpath_count = 0; | |
675 | bool has_joiner = false; | |
676 | gcov_type path_in_count = 0; | |
677 | int path_in_freq = 0; | |
678 | ||
679 | /* Start by accumulating incoming edge counts to the path's first bb | |
680 | into a couple buckets: | |
9943b198 | 681 | path_in_count: total count of incoming edges that flow into the |
682 | current path. | |
683 | nonpath_count: total count of incoming edges that are not | |
684 | flowing along *any* path. These are the counts | |
685 | that will still flow along the original path after | |
686 | all path duplication is done by potentially multiple | |
687 | calls to this routine. | |
30e432bb | 688 | (any other incoming edge counts are for a different jump threading |
689 | path that will be handled by a later call to this routine.) | |
690 | To make this easier, start by recording all incoming edges that flow into | |
691 | the current path in a bitmap. We could add up the path's incoming edge | |
692 | counts here, but we still need to walk all the first bb's incoming edges | |
693 | below to add up the counts of the other edges not included in this jump | |
694 | threading path. */ | |
695 | struct el *next, *el; | |
696 | bitmap in_edge_srcs = BITMAP_ALLOC (NULL); | |
697 | for (el = rd->incoming_edges; el; el = next) | |
698 | { | |
699 | next = el->next; | |
700 | bitmap_set_bit (in_edge_srcs, el->e->src->index); | |
701 | } | |
702 | edge ein; | |
703 | edge_iterator ei; | |
704 | FOR_EACH_EDGE (ein, ei, e->dest->preds) | |
705 | { | |
706 | vec<jump_thread_edge *> *ein_path = THREAD_PATH (ein); | |
707 | /* Simply check the incoming edge src against the set captured above. */ | |
708 | if (ein_path | |
9943b198 | 709 | && bitmap_bit_p (in_edge_srcs, (*ein_path)[0]->e->src->index)) |
710 | { | |
711 | /* It is necessary but not sufficient that the last path edges | |
712 | are identical. There may be different paths that share the | |
713 | same last path edge in the case where the last edge has a nocopy | |
714 | source block. */ | |
715 | gcc_assert (ein_path->last ()->e == elast); | |
716 | path_in_count += ein->count; | |
717 | path_in_freq += EDGE_FREQUENCY (ein); | |
718 | } | |
30e432bb | 719 | else if (!ein_path) |
9943b198 | 720 | { |
721 | /* Keep track of the incoming edges that are not on any jump-threading | |
722 | path. These counts will still flow out of original path after all | |
723 | jump threading is complete. */ | |
724 | nonpath_count += ein->count; | |
725 | } | |
30e432bb | 726 | } |
664dd751 | 727 | |
728 | /* This is needed due to insane incoming frequencies. */ | |
729 | if (path_in_freq > BB_FREQ_MAX) | |
730 | path_in_freq = BB_FREQ_MAX; | |
731 | ||
30e432bb | 732 | BITMAP_FREE (in_edge_srcs); |
733 | ||
734 | /* Now compute the fraction of the total count coming into the first | |
735 | path bb that is from the current threading path. */ | |
736 | gcov_type total_count = e->dest->count; | |
737 | /* Handle incoming profile insanities. */ | |
738 | if (total_count < path_in_count) | |
739 | path_in_count = total_count; | |
740 | int onpath_scale = GCOV_COMPUTE_SCALE (path_in_count, total_count); | |
741 | ||
742 | /* Walk the entire path to do some more computation in order to estimate | |
743 | how much of the path_in_count will flow out of the duplicated threading | |
744 | path. In the non-joiner case this is straightforward (it should be | |
745 | the same as path_in_count, although we will handle incoming profile | |
746 | insanities by setting it equal to the minimum count along the path). | |
747 | ||
748 | In the joiner case, we need to estimate how much of the path_in_count | |
749 | will stay on the threading path after the joiner's conditional branch. | |
750 | We don't really know for sure how much of the counts | |
751 | associated with this path go to each successor of the joiner, but we'll | |
752 | estimate based on the fraction of the total count coming into the path | |
753 | bb was from the threading paths (computed above in onpath_scale). | |
754 | Afterwards, we will need to do some fixup to account for other threading | |
755 | paths and possible profile insanities. | |
756 | ||
757 | In order to estimate the joiner case's counts we also need to update | |
758 | nonpath_count with any additional counts coming into the path. Other | |
759 | blocks along the path may have additional predecessors from outside | |
760 | the path. */ | |
761 | gcov_type path_out_count = path_in_count; | |
762 | gcov_type min_path_count = path_in_count; | |
763 | for (unsigned int i = 1; i < path->length (); i++) | |
764 | { | |
765 | edge epath = (*path)[i]->e; | |
766 | gcov_type cur_count = epath->count; | |
767 | if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
9943b198 | 768 | { |
769 | has_joiner = true; | |
770 | cur_count = apply_probability (cur_count, onpath_scale); | |
771 | } | |
30e432bb | 772 | /* In the joiner case we need to update nonpath_count for any edges |
9943b198 | 773 | coming into the path that will contribute to the count flowing |
774 | into the path successor. */ | |
30e432bb | 775 | if (has_joiner && epath != elast) |
776 | { | |
9943b198 | 777 | /* Look for other incoming edges after joiner. */ |
778 | FOR_EACH_EDGE (ein, ei, epath->dest->preds) | |
779 | { | |
780 | if (ein != epath | |
781 | /* Ignore in edges from blocks we have duplicated for a | |
782 | threading path, which have duplicated edge counts until | |
783 | they are redirected by an invocation of this routine. */ | |
784 | && !bitmap_bit_p (local_info->duplicate_blocks, | |
785 | ein->src->index)) | |
786 | nonpath_count += ein->count; | |
787 | } | |
30e432bb | 788 | } |
789 | if (cur_count < path_out_count) | |
9943b198 | 790 | path_out_count = cur_count; |
30e432bb | 791 | if (epath->count < min_path_count) |
9943b198 | 792 | min_path_count = epath->count; |
30e432bb | 793 | } |
794 | ||
795 | /* We computed path_out_count above assuming that this path targeted | |
796 | the joiner's on-path successor with the same likelihood as it | |
797 | reached the joiner. However, other thread paths through the joiner | |
798 | may take a different path through the normal copy source block | |
799 | (i.e. they have a different elast), meaning that they do not | |
800 | contribute any counts to this path's elast. As a result, it may | |
801 | turn out that this path must have more count flowing to the on-path | |
802 | successor of the joiner. Essentially, all of this path's elast | |
803 | count must be contributed by this path and any nonpath counts | |
804 | (since any path through the joiner with a different elast will not | |
805 | include a copy of this elast in its duplicated path). | |
806 | So ensure that this path's path_out_count is at least the | |
807 | difference between elast->count and nonpath_count. Otherwise the edge | |
808 | counts after threading will not be sane. */ | |
809 | if (has_joiner && path_out_count < elast->count - nonpath_count) | |
810 | { | |
811 | path_out_count = elast->count - nonpath_count; | |
812 | /* But neither can we go above the minimum count along the path | |
813 | we are duplicating. This can be an issue due to profile | |
814 | insanities coming in to this pass. */ | |
815 | if (path_out_count > min_path_count) | |
816 | path_out_count = min_path_count; | |
817 | } | |
818 | ||
819 | *path_in_count_ptr = path_in_count; | |
820 | *path_out_count_ptr = path_out_count; | |
821 | *path_in_freq_ptr = path_in_freq; | |
822 | return has_joiner; | |
823 | } | |
824 | ||
825 | ||
826 | /* Update the counts and frequencies for both an original path | |
827 | edge EPATH and its duplicate EDUP. The duplicate source block | |
828 | will get a count/frequency of PATH_IN_COUNT and PATH_IN_FREQ, | |
829 | and the duplicate edge EDUP will have a count of PATH_OUT_COUNT. */ | |
830 | static void | |
831 | update_profile (edge epath, edge edup, gcov_type path_in_count, | |
9943b198 | 832 | gcov_type path_out_count, int path_in_freq) |
30e432bb | 833 | { |
834 | ||
835 | /* First update the duplicated block's count / frequency. */ | |
836 | if (edup) | |
837 | { | |
838 | basic_block dup_block = edup->src; | |
839 | gcc_assert (dup_block->count == 0); | |
840 | gcc_assert (dup_block->frequency == 0); | |
841 | dup_block->count = path_in_count; | |
842 | dup_block->frequency = path_in_freq; | |
843 | } | |
844 | ||
845 | /* Now update the original block's count and frequency in the | |
846 | opposite manner - remove the counts/freq that will flow | |
847 | into the duplicated block. Handle underflow due to precision/ | |
848 | rounding issues. */ | |
849 | epath->src->count -= path_in_count; | |
850 | if (epath->src->count < 0) | |
851 | epath->src->count = 0; | |
852 | epath->src->frequency -= path_in_freq; | |
853 | if (epath->src->frequency < 0) | |
854 | epath->src->frequency = 0; | |
855 | ||
856 | /* Next update this path edge's original and duplicated counts. We know | |
857 | that the duplicated path will have path_out_count flowing | |
858 | out of it (in the joiner case this is the count along the duplicated path | |
859 | out of the duplicated joiner). This count can then be removed from the | |
860 | original path edge. */ | |
861 | if (edup) | |
862 | edup->count = path_out_count; | |
863 | epath->count -= path_out_count; | |
864 | gcc_assert (epath->count >= 0); | |
865 | } | |
866 | ||
867 | ||
868 | /* The duplicate and original joiner blocks may end up with different | |
869 | probabilities (different from both the original and from each other). | |
870 | Recompute the probabilities here once we have updated the edge | |
871 | counts and frequencies. */ | |
872 | ||
873 | static void | |
874 | recompute_probabilities (basic_block bb) | |
875 | { | |
876 | edge esucc; | |
877 | edge_iterator ei; | |
878 | FOR_EACH_EDGE (esucc, ei, bb->succs) | |
879 | { | |
bdd367a0 | 880 | if (!bb->count) |
9943b198 | 881 | continue; |
bdd367a0 | 882 | |
883 | /* Prevent overflow computation due to insane profiles. */ | |
884 | if (esucc->count < bb->count) | |
9943b198 | 885 | esucc->probability = GCOV_COMPUTE_SCALE (esucc->count, |
886 | bb->count); | |
bdd367a0 | 887 | else |
9943b198 | 888 | /* Can happen with missing/guessed probabilities, since we |
889 | may determine that more is flowing along duplicated | |
890 | path than joiner succ probabilities allowed. | |
891 | Counts and freqs will be insane after jump threading, | |
892 | at least make sure probability is sane or we will | |
893 | get a flow verification error. | |
894 | Not much we can do to make counts/freqs sane without | |
895 | redoing the profile estimation. */ | |
896 | esucc->probability = REG_BR_PROB_BASE; | |
30e432bb | 897 | } |
898 | } | |
899 | ||
900 | ||
901 | /* Update the counts of the original and duplicated edges from a joiner | |
902 | that go off path, given that we have already determined that the | |
903 | duplicate joiner DUP_BB has incoming count PATH_IN_COUNT and | |
904 | outgoing count along the path PATH_OUT_COUNT. The original (on-)path | |
905 | edge from joiner is EPATH. */ | |
906 | ||
907 | static void | |
908 | update_joiner_offpath_counts (edge epath, basic_block dup_bb, | |
9943b198 | 909 | gcov_type path_in_count, |
910 | gcov_type path_out_count) | |
30e432bb | 911 | { |
912 | /* Compute the count that currently flows off path from the joiner. | |
913 | In other words, the total count of joiner's out edges other than | |
914 | epath. Compute this by walking the successors instead of | |
915 | subtracting epath's count from the joiner bb count, since there | |
916 | are sometimes slight insanities where the total out edge count is | |
917 | larger than the bb count (possibly due to rounding/truncation | |
918 | errors). */ | |
919 | gcov_type total_orig_off_path_count = 0; | |
920 | edge enonpath; | |
921 | edge_iterator ei; | |
922 | FOR_EACH_EDGE (enonpath, ei, epath->src->succs) | |
923 | { | |
924 | if (enonpath == epath) | |
9943b198 | 925 | continue; |
30e432bb | 926 | total_orig_off_path_count += enonpath->count; |
927 | } | |
928 | ||
929 | /* For the path that we are duplicating, the amount that will flow | |
930 | off path from the duplicated joiner is the delta between the | |
931 | path's cumulative in count and the portion of that count we | |
932 | estimated above as flowing from the joiner along the duplicated | |
933 | path. */ | |
934 | gcov_type total_dup_off_path_count = path_in_count - path_out_count; | |
935 | ||
936 | /* Now do the actual updates of the off-path edges. */ | |
937 | FOR_EACH_EDGE (enonpath, ei, epath->src->succs) | |
938 | { | |
939 | /* Look for edges going off of the threading path. */ | |
940 | if (enonpath == epath) | |
9943b198 | 941 | continue; |
30e432bb | 942 | |
943 | /* Find the corresponding edge out of the duplicated joiner. */ | |
944 | edge enonpathdup = find_edge (dup_bb, enonpath->dest); | |
945 | gcc_assert (enonpathdup); | |
946 | ||
947 | /* We can't use the original probability of the joiner's out | |
9943b198 | 948 | edges, since the probabilities of the original branch |
949 | and the duplicated branches may vary after all threading is | |
950 | complete. But apportion the duplicated joiner's off-path | |
951 | total edge count computed earlier (total_dup_off_path_count) | |
952 | among the duplicated off-path edges based on their original | |
953 | ratio to the full off-path count (total_orig_off_path_count). | |
954 | */ | |
30e432bb | 955 | int scale = GCOV_COMPUTE_SCALE (enonpath->count, |
9943b198 | 956 | total_orig_off_path_count); |
30e432bb | 957 | /* Give the duplicated offpath edge a portion of the duplicated |
9943b198 | 958 | total. */ |
30e432bb | 959 | enonpathdup->count = apply_scale (scale, |
9943b198 | 960 | total_dup_off_path_count); |
30e432bb | 961 | /* Now update the original offpath edge count, handling underflow |
9943b198 | 962 | due to rounding errors. */ |
30e432bb | 963 | enonpath->count -= enonpathdup->count; |
964 | if (enonpath->count < 0) | |
9943b198 | 965 | enonpath->count = 0; |
30e432bb | 966 | } |
967 | } | |
968 | ||
969 | ||
f1ce4e72 | 970 | /* Check if the paths through RD all have estimated frequencies but zero |
971 | profile counts. This is more accurate than checking the entry block | |
972 | for a zero profile count, since profile insanities sometimes creep in. */ | |
973 | ||
974 | static bool | |
975 | estimated_freqs_path (struct redirection_data *rd) | |
976 | { | |
977 | edge e = rd->incoming_edges->e; | |
978 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
979 | edge ein; | |
980 | edge_iterator ei; | |
981 | bool non_zero_freq = false; | |
982 | FOR_EACH_EDGE (ein, ei, e->dest->preds) | |
983 | { | |
984 | if (ein->count) | |
9943b198 | 985 | return false; |
f1ce4e72 | 986 | non_zero_freq |= ein->src->frequency != 0; |
987 | } | |
988 | ||
989 | for (unsigned int i = 1; i < path->length (); i++) | |
990 | { | |
991 | edge epath = (*path)[i]->e; | |
992 | if (epath->src->count) | |
9943b198 | 993 | return false; |
f1ce4e72 | 994 | non_zero_freq |= epath->src->frequency != 0; |
995 | edge esucc; | |
996 | FOR_EACH_EDGE (esucc, ei, epath->src->succs) | |
9943b198 | 997 | { |
998 | if (esucc->count) | |
999 | return false; | |
1000 | non_zero_freq |= esucc->src->frequency != 0; | |
1001 | } | |
f1ce4e72 | 1002 | } |
1003 | return non_zero_freq; | |
1004 | } | |
1005 | ||
1006 | ||
30e432bb | 1007 | /* Invoked for routines that have guessed frequencies and no profile |
1008 | counts to record the block and edge frequencies for paths through RD | |
1009 | in the profile count fields of those blocks and edges. This is because | |
1010 | ssa_fix_duplicate_block_edges incrementally updates the block and | |
1011 | edge counts as edges are redirected, and it is difficult to do that | |
1012 | for edge frequencies which are computed on the fly from the source | |
1013 | block frequency and probability. When a block frequency is updated | |
1014 | its outgoing edge frequencies are affected and become difficult to | |
1015 | adjust. */ | |
1016 | ||
1017 | static void | |
1018 | freqs_to_counts_path (struct redirection_data *rd) | |
1019 | { | |
1020 | edge e = rd->incoming_edges->e; | |
1021 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
1022 | edge ein; | |
1023 | edge_iterator ei; | |
1024 | FOR_EACH_EDGE (ein, ei, e->dest->preds) | |
e8038c32 | 1025 | { |
1026 | /* Scale up the frequency by REG_BR_PROB_BASE, to avoid rounding | |
9943b198 | 1027 | errors applying the probability when the frequencies are very |
1028 | small. */ | |
e8038c32 | 1029 | ein->count = apply_probability (ein->src->frequency * REG_BR_PROB_BASE, |
9943b198 | 1030 | ein->probability); |
e8038c32 | 1031 | } |
30e432bb | 1032 | |
1033 | for (unsigned int i = 1; i < path->length (); i++) | |
1034 | { | |
1035 | edge epath = (*path)[i]->e; | |
30e432bb | 1036 | edge esucc; |
e8038c32 | 1037 | /* Scale up the frequency by REG_BR_PROB_BASE, to avoid rounding |
9943b198 | 1038 | errors applying the edge probability when the frequencies are very |
1039 | small. */ | |
e8038c32 | 1040 | epath->src->count = epath->src->frequency * REG_BR_PROB_BASE; |
30e432bb | 1041 | FOR_EACH_EDGE (esucc, ei, epath->src->succs) |
9943b198 | 1042 | esucc->count = apply_probability (esucc->src->count, |
1043 | esucc->probability); | |
30e432bb | 1044 | } |
1045 | } | |
1046 | ||
1047 | ||
1048 | /* For routines that have guessed frequencies and no profile counts, where we | |
1049 | used freqs_to_counts_path to record block and edge frequencies for paths | |
1050 | through RD, we clear the counts after completing all updates for RD. | |
1051 | The updates in ssa_fix_duplicate_block_edges are based off the count fields, | |
1052 | but the block frequencies and edge probabilities were updated as well, | |
1053 | so we can simply clear the count fields. */ | |
1054 | ||
1055 | static void | |
1056 | clear_counts_path (struct redirection_data *rd) | |
1057 | { | |
1058 | edge e = rd->incoming_edges->e; | |
1059 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
1060 | edge ein, esucc; | |
1061 | edge_iterator ei; | |
1062 | FOR_EACH_EDGE (ein, ei, e->dest->preds) | |
1063 | ein->count = 0; | |
1064 | ||
1065 | /* First clear counts along original path. */ | |
1066 | for (unsigned int i = 1; i < path->length (); i++) | |
1067 | { | |
1068 | edge epath = (*path)[i]->e; | |
1069 | FOR_EACH_EDGE (esucc, ei, epath->src->succs) | |
9943b198 | 1070 | esucc->count = 0; |
30e432bb | 1071 | epath->src->count = 0; |
1072 | } | |
1073 | /* Also need to clear the counts along duplicated path. */ | |
1074 | for (unsigned int i = 0; i < 2; i++) | |
1075 | { | |
1076 | basic_block dup = rd->dup_blocks[i]; | |
1077 | if (!dup) | |
9943b198 | 1078 | continue; |
30e432bb | 1079 | FOR_EACH_EDGE (esucc, ei, dup->succs) |
9943b198 | 1080 | esucc->count = 0; |
30e432bb | 1081 | dup->count = 0; |
1082 | } | |
1083 | } | |
1084 | ||
fc54aba7 | 1085 | /* Wire up the outgoing edges from the duplicate blocks and |
30e432bb | 1086 | update any PHIs as needed. Also update the profile counts |
1087 | on the original and duplicate blocks and edges. */ | |
2b15d2ba | 1088 | void |
1089 | ssa_fix_duplicate_block_edges (struct redirection_data *rd, | |
1090 | ssa_local_info_t *local_info) | |
da81e0c5 | 1091 | { |
1b83c31b | 1092 | bool multi_incomings = (rd->incoming_edges->next != NULL); |
f2981b08 | 1093 | edge e = rd->incoming_edges->e; |
1094 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
30e432bb | 1095 | edge elast = path->last ()->e; |
1096 | gcov_type path_in_count = 0; | |
1097 | gcov_type path_out_count = 0; | |
1098 | int path_in_freq = 0; | |
1099 | ||
1100 | /* This routine updates profile counts, frequencies, and probabilities | |
1101 | incrementally. Since it is difficult to do the incremental updates | |
1102 | using frequencies/probabilities alone, for routines without profile | |
1103 | data we first take a snapshot of the existing block and edge frequencies | |
1104 | by copying them into the empty profile count fields. These counts are | |
1105 | then used to do the incremental updates, and cleared at the end of this | |
f1ce4e72 | 1106 | routine. If the function is marked as having a profile, we still check |
1107 | to see if the paths through RD are using estimated frequencies because | |
1108 | the routine had zero profile counts. */ | |
30e432bb | 1109 | bool do_freqs_to_counts = (profile_status_for_fn (cfun) != PROFILE_READ |
9943b198 | 1110 | || estimated_freqs_path (rd)); |
30e432bb | 1111 | if (do_freqs_to_counts) |
1112 | freqs_to_counts_path (rd); | |
1113 | ||
1114 | /* First determine how much profile count to move from original | |
1115 | path to the duplicate path. This is tricky in the presence of | |
1116 | a joiner (see comments for compute_path_counts), where some portion | |
1117 | of the path's counts will flow off-path from the joiner. In the | |
1118 | non-joiner case the path_in_count and path_out_count should be the | |
1119 | same. */ | |
1120 | bool has_joiner = compute_path_counts (rd, local_info, | |
9943b198 | 1121 | &path_in_count, &path_out_count, |
1122 | &path_in_freq); | |
30e432bb | 1123 | |
1124 | int cur_path_freq = path_in_freq; | |
fc54aba7 | 1125 | for (unsigned int count = 0, i = 1; i < path->length (); i++) |
1b83778e | 1126 | { |
30e432bb | 1127 | edge epath = (*path)[i]->e; |
1128 | ||
fc54aba7 | 1129 | /* If we were threading through an joiner block, then we want |
1130 | to keep its control statement and redirect an outgoing edge. | |
1131 | Else we want to remove the control statement & edges, then create | |
1132 | a new outgoing edge. In both cases we may need to update PHIs. */ | |
1133 | if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
1134 | { | |
1135 | edge victim; | |
1136 | edge e2; | |
1137 | ||
9943b198 | 1138 | gcc_assert (has_joiner); |
30e432bb | 1139 | |
fc54aba7 | 1140 | /* This updates the PHIs at the destination of the duplicate |
1b83c31b | 1141 | block. Pass 0 instead of i if we are threading a path which |
1142 | has multiple incoming edges. */ | |
1143 | update_destination_phis (local_info->bb, rd->dup_blocks[count], | |
1144 | path, multi_incomings ? 0 : i); | |
fc54aba7 | 1145 | |
1146 | /* Find the edge from the duplicate block to the block we're | |
1147 | threading through. That's the edge we want to redirect. */ | |
1148 | victim = find_edge (rd->dup_blocks[count], (*path)[i]->e->dest); | |
1149 | ||
1150 | /* If there are no remaining blocks on the path to duplicate, | |
1151 | then redirect VICTIM to the final destination of the jump | |
1152 | threading path. */ | |
1153 | if (!any_remaining_duplicated_blocks (path, i)) | |
1154 | { | |
30e432bb | 1155 | e2 = redirect_edge_and_branch (victim, elast->dest); |
fc54aba7 | 1156 | /* If we redirected the edge, then we need to copy PHI arguments |
559685be | 1157 | at the target. If the edge already existed (e2 != victim |
fc54aba7 | 1158 | case), then the PHIs in the target already have the correct |
1159 | arguments. */ | |
1160 | if (e2 == victim) | |
30e432bb | 1161 | copy_phi_args (e2->dest, elast, e2, |
1b83c31b | 1162 | path, multi_incomings ? 0 : i); |
fc54aba7 | 1163 | } |
1164 | else | |
1165 | { | |
1166 | /* Redirect VICTIM to the next duplicated block in the path. */ | |
1167 | e2 = redirect_edge_and_branch (victim, rd->dup_blocks[count + 1]); | |
1168 | ||
1169 | /* We need to update the PHIs in the next duplicated block. We | |
1170 | want the new PHI args to have the same value as they had | |
1171 | in the source of the next duplicate block. | |
1172 | ||
1173 | Thus, we need to know which edge we traversed into the | |
1174 | source of the duplicate. Furthermore, we may have | |
1175 | traversed many edges to reach the source of the duplicate. | |
1176 | ||
1177 | Walk through the path starting at element I until we | |
1178 | hit an edge marked with EDGE_COPY_SRC_BLOCK. We want | |
1179 | the edge from the prior element. */ | |
1180 | for (unsigned int j = i + 1; j < path->length (); j++) | |
1181 | { | |
1182 | if ((*path)[j]->type == EDGE_COPY_SRC_BLOCK) | |
1183 | { | |
1184 | copy_phi_arg_into_existing_phi ((*path)[j - 1]->e, e2); | |
1185 | break; | |
1186 | } | |
1187 | } | |
1188 | } | |
30e432bb | 1189 | |
1190 | /* Update the counts and frequency of both the original block | |
1191 | and path edge, and the duplicates. The path duplicate's | |
1192 | incoming count and frequency are the totals for all edges | |
1193 | incoming to this jump threading path computed earlier. | |
1194 | And we know that the duplicated path will have path_out_count | |
1195 | flowing out of it (i.e. along the duplicated path out of the | |
1196 | duplicated joiner). */ | |
1197 | update_profile (epath, e2, path_in_count, path_out_count, | |
1198 | path_in_freq); | |
1199 | ||
1200 | /* Next we need to update the counts of the original and duplicated | |
1201 | edges from the joiner that go off path. */ | |
1202 | update_joiner_offpath_counts (epath, e2->src, path_in_count, | |
9943b198 | 1203 | path_out_count); |
30e432bb | 1204 | |
1205 | /* Finally, we need to set the probabilities on the duplicated | |
1206 | edges out of the duplicated joiner (e2->src). The probabilities | |
1207 | along the original path will all be updated below after we finish | |
1208 | processing the whole path. */ | |
1209 | recompute_probabilities (e2->src); | |
1210 | ||
1211 | /* Record the frequency flowing to the downstream duplicated | |
1212 | path blocks. */ | |
1213 | cur_path_freq = EDGE_FREQUENCY (e2); | |
fc54aba7 | 1214 | } |
1215 | else if ((*path)[i]->type == EDGE_COPY_SRC_BLOCK) | |
1216 | { | |
1217 | remove_ctrl_stmt_and_useless_edges (rd->dup_blocks[count], NULL); | |
1b83c31b | 1218 | create_edge_and_update_destination_phis (rd, rd->dup_blocks[count], |
1219 | multi_incomings ? 0 : i); | |
fc54aba7 | 1220 | if (count == 1) |
1221 | single_succ_edge (rd->dup_blocks[1])->aux = NULL; | |
30e432bb | 1222 | |
1223 | /* Update the counts and frequency of both the original block | |
1224 | and path edge, and the duplicates. Since we are now after | |
1225 | any joiner that may have existed on the path, the count | |
1226 | flowing along the duplicated threaded path is path_out_count. | |
1227 | If we didn't have a joiner, then cur_path_freq was the sum | |
1228 | of the total frequencies along all incoming edges to the | |
1229 | thread path (path_in_freq). If we had a joiner, it would have | |
1230 | been updated at the end of that handling to the edge frequency | |
1231 | along the duplicated joiner path edge. */ | |
1232 | update_profile (epath, EDGE_SUCC (rd->dup_blocks[count], 0), | |
1233 | path_out_count, path_out_count, | |
1234 | cur_path_freq); | |
fc54aba7 | 1235 | } |
30e432bb | 1236 | else |
9943b198 | 1237 | { |
30e432bb | 1238 | /* No copy case. In this case we don't have an equivalent block |
1239 | on the duplicated thread path to update, but we do need | |
1240 | to remove the portion of the counts/freqs that were moved | |
1241 | to the duplicated path from the counts/freqs flowing through | |
1242 | this block on the original path. Since all the no-copy edges | |
1243 | are after any joiner, the removed count is the same as | |
1244 | path_out_count. | |
1245 | ||
1246 | If we didn't have a joiner, then cur_path_freq was the sum | |
1247 | of the total frequencies along all incoming edges to the | |
1248 | thread path (path_in_freq). If we had a joiner, it would have | |
1249 | been updated at the end of that handling to the edge frequency | |
1250 | along the duplicated joiner path edge. */ | |
1251 | update_profile (epath, NULL, path_out_count, path_out_count, | |
1252 | cur_path_freq); | |
1253 | } | |
1254 | ||
1255 | /* Increment the index into the duplicated path when we processed | |
9943b198 | 1256 | a duplicated block. */ |
30e432bb | 1257 | if ((*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK |
9943b198 | 1258 | || (*path)[i]->type == EDGE_COPY_SRC_BLOCK) |
30e432bb | 1259 | { |
1260 | count++; | |
1261 | } | |
1262 | } | |
1263 | ||
1264 | /* Now walk orig blocks and update their probabilities, since the | |
1265 | counts and freqs should be updated properly by above loop. */ | |
1266 | for (unsigned int i = 1; i < path->length (); i++) | |
1267 | { | |
1268 | edge epath = (*path)[i]->e; | |
1269 | recompute_probabilities (epath->src); | |
778182c1 | 1270 | } |
30e432bb | 1271 | |
1272 | /* Done with all profile and frequency updates, clear counts if they | |
1273 | were copied. */ | |
1274 | if (do_freqs_to_counts) | |
1275 | clear_counts_path (rd); | |
778182c1 | 1276 | } |
fc54aba7 | 1277 | |
778182c1 | 1278 | /* Hash table traversal callback routine to create duplicate blocks. */ |
1279 | ||
2b15d2ba | 1280 | int |
1281 | ssa_create_duplicates (struct redirection_data **slot, | |
1282 | ssa_local_info_t *local_info) | |
778182c1 | 1283 | { |
2b15d2ba | 1284 | struct redirection_data *rd = *slot; |
778182c1 | 1285 | |
11af02d8 | 1286 | /* The second duplicated block in a jump threading path is specific |
1b83778e | 1287 | to the path. So it gets stored in RD rather than in LOCAL_DATA. |
559685be | 1288 | |
11af02d8 | 1289 | Each time we're called, we have to look through the path and see |
1b83778e | 1290 | if a second block needs to be duplicated. |
11af02d8 | 1291 | |
1292 | Note the search starts with the third edge on the path. The first | |
1293 | edge is the incoming edge, the second edge always has its source | |
1294 | duplicated. Thus we start our search with the third edge. */ | |
a7ee7309 | 1295 | vec<jump_thread_edge *> *path = rd->path; |
11af02d8 | 1296 | for (unsigned int i = 2; i < path->length (); i++) |
1297 | { | |
1298 | if ((*path)[i]->type == EDGE_COPY_SRC_BLOCK | |
1299 | || (*path)[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
1300 | { | |
30e432bb | 1301 | create_block_for_threading ((*path)[i]->e->src, rd, 1, |
a7ee7309 | 1302 | &local_info->duplicate_blocks); |
11af02d8 | 1303 | break; |
1304 | } | |
1305 | } | |
1b83778e | 1306 | |
778182c1 | 1307 | /* Create a template block if we have not done so already. Otherwise |
1308 | use the template to create a new block. */ | |
1309 | if (local_info->template_block == NULL) | |
1310 | { | |
30e432bb | 1311 | create_block_for_threading ((*path)[1]->e->src, rd, 0, |
a7ee7309 | 1312 | &local_info->duplicate_blocks); |
11af02d8 | 1313 | local_info->template_block = rd->dup_blocks[0]; |
778182c1 | 1314 | |
1315 | /* We do not create any outgoing edges for the template. We will | |
1316 | take care of that in a later traversal. That way we do not | |
1317 | create edges that are going to just be deleted. */ | |
1318 | } | |
1319 | else | |
1320 | { | |
30e432bb | 1321 | create_block_for_threading (local_info->template_block, rd, 0, |
a7ee7309 | 1322 | &local_info->duplicate_blocks); |
778182c1 | 1323 | |
1324 | /* Go ahead and wire up outgoing edges and update PHIs for the duplicate | |
da81e0c5 | 1325 | block. */ |
2b15d2ba | 1326 | ssa_fix_duplicate_block_edges (rd, local_info); |
778182c1 | 1327 | } |
1328 | ||
1329 | /* Keep walking the hash table. */ | |
1330 | return 1; | |
1331 | } | |
1332 | ||
1333 | /* We did not create any outgoing edges for the template block during | |
1334 | block creation. This hash table traversal callback creates the | |
1335 | outgoing edge for the template block. */ | |
1336 | ||
2b15d2ba | 1337 | inline int |
1338 | ssa_fixup_template_block (struct redirection_data **slot, | |
1339 | ssa_local_info_t *local_info) | |
778182c1 | 1340 | { |
2b15d2ba | 1341 | struct redirection_data *rd = *slot; |
778182c1 | 1342 | |
da81e0c5 | 1343 | /* If this is the template block halt the traversal after updating |
1344 | it appropriately. | |
1345 | ||
1346 | If we were threading through an joiner block, then we want | |
1347 | to keep its control statement and redirect an outgoing edge. | |
1348 | Else we want to remove the control statement & edges, then create | |
1349 | a new outgoing edge. In both cases we may need to update PHIs. */ | |
11af02d8 | 1350 | if (rd->dup_blocks[0] && rd->dup_blocks[0] == local_info->template_block) |
778182c1 | 1351 | { |
2b15d2ba | 1352 | ssa_fix_duplicate_block_edges (rd, local_info); |
778182c1 | 1353 | return 0; |
1354 | } | |
1355 | ||
1356 | return 1; | |
1357 | } | |
1358 | ||
1359 | /* Hash table traversal callback to redirect each incoming edge | |
1360 | associated with this hash table element to its new destination. */ | |
1361 | ||
2b15d2ba | 1362 | int |
1363 | ssa_redirect_edges (struct redirection_data **slot, | |
1364 | ssa_local_info_t *local_info) | |
778182c1 | 1365 | { |
2b15d2ba | 1366 | struct redirection_data *rd = *slot; |
778182c1 | 1367 | struct el *next, *el; |
1368 | ||
47ae02b7 | 1369 | /* Walk over all the incoming edges associated with this hash table |
1370 | entry. */ | |
778182c1 | 1371 | for (el = rd->incoming_edges; el; el = next) |
1372 | { | |
1373 | edge e = el->e; | |
f2981b08 | 1374 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
778182c1 | 1375 | |
1376 | /* Go ahead and free this element from the list. Doing this now | |
1377 | avoids the need for another list walk when we destroy the hash | |
1378 | table. */ | |
1379 | next = el->next; | |
1380 | free (el); | |
1381 | ||
5236b8bb | 1382 | thread_stats.num_threaded_edges++; |
1383 | ||
11af02d8 | 1384 | if (rd->dup_blocks[0]) |
778182c1 | 1385 | { |
1386 | edge e2; | |
1387 | ||
1388 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1389 | fprintf (dump_file, " Threaded jump %d --> %d to %d\n", | |
11af02d8 | 1390 | e->src->index, e->dest->index, rd->dup_blocks[0]->index); |
778182c1 | 1391 | |
c08f3525 | 1392 | /* If we redirect a loop latch edge cancel its loop. */ |
1393 | if (e->src == e->src->loop_father->latch) | |
d25159cc | 1394 | mark_loop_for_removal (e->src->loop_father); |
c08f3525 | 1395 | |
353f9f16 | 1396 | /* Redirect the incoming edge (possibly to the joiner block) to the |
1397 | appropriate duplicate block. */ | |
11af02d8 | 1398 | e2 = redirect_edge_and_branch (e, rd->dup_blocks[0]); |
7e0311ae | 1399 | gcc_assert (e == e2); |
778182c1 | 1400 | flush_pending_stmts (e2); |
778182c1 | 1401 | } |
eb31063a | 1402 | |
1403 | /* Go ahead and clear E->aux. It's not needed anymore and failure | |
559685be | 1404 | to clear it will cause all kinds of unpleasant problems later. */ |
6d1fdbf9 | 1405 | delete_jump_thread_path (path); |
eb31063a | 1406 | e->aux = NULL; |
1407 | ||
778182c1 | 1408 | } |
388d1fc1 | 1409 | |
1410 | /* Indicate that we actually threaded one or more jumps. */ | |
1411 | if (rd->incoming_edges) | |
1412 | local_info->jumps_threaded = true; | |
1413 | ||
778182c1 | 1414 | return 1; |
1415 | } | |
1416 | ||
aed95130 | 1417 | /* Return true if this block has no executable statements other than |
1418 | a simple ctrl flow instruction. When the number of outgoing edges | |
1419 | is one, this is equivalent to a "forwarder" block. */ | |
1420 | ||
1421 | static bool | |
47aaf6e6 | 1422 | redirection_block_p (basic_block bb) |
aed95130 | 1423 | { |
75a70cf9 | 1424 | gimple_stmt_iterator gsi; |
aed95130 | 1425 | |
1426 | /* Advance to the first executable statement. */ | |
75a70cf9 | 1427 | gsi = gsi_start_bb (bb); |
1428 | while (!gsi_end_p (gsi) | |
559685be | 1429 | && (gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL |
9845d120 | 1430 | || is_gimple_debug (gsi_stmt (gsi)) |
c7566ddf | 1431 | || gimple_nop_p (gsi_stmt (gsi)) |
581c1a3c | 1432 | || gimple_clobber_p (gsi_stmt (gsi)))) |
75a70cf9 | 1433 | gsi_next (&gsi); |
48e1416a | 1434 | |
aed95130 | 1435 | /* Check if this is an empty block. */ |
75a70cf9 | 1436 | if (gsi_end_p (gsi)) |
aed95130 | 1437 | return true; |
1438 | ||
1439 | /* Test that we've reached the terminating control statement. */ | |
75a70cf9 | 1440 | return gsi_stmt (gsi) |
559685be | 1441 | && (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND |
1442 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_GOTO | |
1443 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_SWITCH); | |
aed95130 | 1444 | } |
1445 | ||
a8046f60 | 1446 | /* BB is a block which ends with a COND_EXPR or SWITCH_EXPR and when BB |
1447 | is reached via one or more specific incoming edges, we know which | |
1448 | outgoing edge from BB will be traversed. | |
1449 | ||
778182c1 | 1450 | We want to redirect those incoming edges to the target of the |
a8046f60 | 1451 | appropriate outgoing edge. Doing so avoids a conditional branch |
1452 | and may expose new optimization opportunities. Note that we have | |
1453 | to update dominator tree and SSA graph after such changes. | |
1454 | ||
597ff315 | 1455 | The key to keeping the SSA graph update manageable is to duplicate |
91275768 | 1456 | the side effects occurring in BB so that those side effects still |
a8046f60 | 1457 | occur on the paths which bypass BB after redirecting edges. |
1458 | ||
1459 | We accomplish this by creating duplicates of BB and arranging for | |
1460 | the duplicates to unconditionally pass control to one specific | |
1461 | successor of BB. We then revector the incoming edges into BB to | |
1462 | the appropriate duplicate of BB. | |
1463 | ||
7e0311ae | 1464 | If NOLOOP_ONLY is true, we only perform the threading as long as it |
1b83778e | 1465 | does not affect the structure of the loops in a nontrivial way. |
ed4feca1 | 1466 | |
1467 | If JOINERS is true, then thread through joiner blocks as well. */ | |
a8046f60 | 1468 | |
388d1fc1 | 1469 | static bool |
ed4feca1 | 1470 | thread_block_1 (basic_block bb, bool noloop_only, bool joiners) |
a8046f60 | 1471 | { |
1472 | /* E is an incoming edge into BB that we may or may not want to | |
1473 | redirect to a duplicate of BB. */ | |
7e0311ae | 1474 | edge e, e2; |
cd665a06 | 1475 | edge_iterator ei; |
2b15d2ba | 1476 | ssa_local_info_t local_info; |
388d1fc1 | 1477 | |
30e432bb | 1478 | local_info.duplicate_blocks = BITMAP_ALLOC (NULL); |
1479 | ||
778182c1 | 1480 | /* To avoid scanning a linear array for the element we need we instead |
c5d4a10b | 1481 | use a hash table. For normal code there should be no noticeable |
778182c1 | 1482 | difference. However, if we have a block with a large number of |
1483 | incoming and outgoing edges such linear searches can get expensive. */ | |
c1f445d2 | 1484 | redirection_data |
1485 | = new hash_table<struct redirection_data> (EDGE_COUNT (bb->succs)); | |
778182c1 | 1486 | |
1487 | /* Record each unique threaded destination into a hash table for | |
1488 | efficient lookups. */ | |
cd665a06 | 1489 | FOR_EACH_EDGE (e, ei, bb->preds) |
a8046f60 | 1490 | { |
eb31063a | 1491 | if (e->aux == NULL) |
1492 | continue; | |
1493 | ||
f2981b08 | 1494 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
ed4feca1 | 1495 | |
1496 | if (((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK && !joiners) | |
1497 | || ((*path)[1]->type == EDGE_COPY_SRC_BLOCK && joiners)) | |
1498 | continue; | |
1499 | ||
f2981b08 | 1500 | e2 = path->last ()->e; |
e2b72d6c | 1501 | if (!e2 || noloop_only) |
1502 | { | |
7e0311ae | 1503 | /* If NOLOOP_ONLY is true, we only allow threading through the |
559685be | 1504 | header of a loop to exit edges. */ |
e2b72d6c | 1505 | |
559685be | 1506 | /* One case occurs when there was loop header buried in a jump |
1507 | threading path that crosses loop boundaries. We do not try | |
1508 | and thread this elsewhere, so just cancel the jump threading | |
1509 | request by clearing the AUX field now. */ | |
bb66e2d1 | 1510 | if ((bb->loop_father != e2->src->loop_father |
1511 | && !loop_exit_edge_p (e2->src->loop_father, e2)) | |
1512 | || (e2->src->loop_father != e2->dest->loop_father | |
1513 | && !loop_exit_edge_p (e2->src->loop_father, e2))) | |
e2b72d6c | 1514 | { |
1515 | /* Since this case is not handled by our special code | |
1516 | to thread through a loop header, we must explicitly | |
1517 | cancel the threading request here. */ | |
6d1fdbf9 | 1518 | delete_jump_thread_path (path); |
e2b72d6c | 1519 | e->aux = NULL; |
1520 | continue; | |
1521 | } | |
559685be | 1522 | |
1523 | /* Another case occurs when trying to thread through our | |
ab596744 | 1524 | own loop header, possibly from inside the loop. We will |
1525 | thread these later. */ | |
559685be | 1526 | unsigned int i; |
1527 | for (i = 1; i < path->length (); i++) | |
1528 | { | |
1529 | if ((*path)[i]->e->src == bb->loop_father->header | |
1530 | && (!loop_exit_edge_p (bb->loop_father, e2) | |
1531 | || (*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK)) | |
ab596744 | 1532 | break; |
559685be | 1533 | } |
1534 | ||
1535 | if (i != path->length ()) | |
1536 | continue; | |
e2b72d6c | 1537 | } |
778182c1 | 1538 | |
7e0311ae | 1539 | /* Insert the outgoing edge into the hash table if it is not |
1540 | already in the hash table. */ | |
da81e0c5 | 1541 | lookup_redirection_data (e, INSERT); |
a8046f60 | 1542 | } |
1543 | ||
3f9439d7 | 1544 | /* We do not update dominance info. */ |
1545 | free_dominance_info (CDI_DOMINATORS); | |
1546 | ||
d906930c | 1547 | /* We know we only thread through the loop header to loop exits. |
1548 | Let the basic block duplication hook know we are not creating | |
1549 | a multiple entry loop. */ | |
1550 | if (noloop_only | |
1551 | && bb == bb->loop_father->header) | |
1552 | set_loop_copy (bb->loop_father, loop_outer (bb->loop_father)); | |
1553 | ||
778182c1 | 1554 | /* Now create duplicates of BB. |
f582bb6c | 1555 | |
1556 | Note that for a block with a high outgoing degree we can waste | |
1557 | a lot of time and memory creating and destroying useless edges. | |
1558 | ||
1559 | So we first duplicate BB and remove the control structure at the | |
1560 | tail of the duplicate as well as all outgoing edges from the | |
1561 | duplicate. We then use that duplicate block as a template for | |
1562 | the rest of the duplicates. */ | |
778182c1 | 1563 | local_info.template_block = NULL; |
1564 | local_info.bb = bb; | |
388d1fc1 | 1565 | local_info.jumps_threaded = false; |
c1f445d2 | 1566 | redirection_data->traverse <ssa_local_info_t *, ssa_create_duplicates> |
2b15d2ba | 1567 | (&local_info); |
f582bb6c | 1568 | |
778182c1 | 1569 | /* The template does not have an outgoing edge. Create that outgoing |
1570 | edge and update PHI nodes as the edge's target as necessary. | |
f582bb6c | 1571 | |
778182c1 | 1572 | We do this after creating all the duplicates to avoid creating |
1573 | unnecessary edges. */ | |
c1f445d2 | 1574 | redirection_data->traverse <ssa_local_info_t *, ssa_fixup_template_block> |
2b15d2ba | 1575 | (&local_info); |
f582bb6c | 1576 | |
778182c1 | 1577 | /* The hash table traversals above created the duplicate blocks (and the |
1578 | statements within the duplicate blocks). This loop creates PHI nodes for | |
1579 | the duplicated blocks and redirects the incoming edges into BB to reach | |
1580 | the duplicates of BB. */ | |
c1f445d2 | 1581 | redirection_data->traverse <ssa_local_info_t *, ssa_redirect_edges> |
2b15d2ba | 1582 | (&local_info); |
a8046f60 | 1583 | |
a3d0fd80 | 1584 | /* Done with this block. Clear REDIRECTION_DATA. */ |
c1f445d2 | 1585 | delete redirection_data; |
1586 | redirection_data = NULL; | |
388d1fc1 | 1587 | |
d906930c | 1588 | if (noloop_only |
1589 | && bb == bb->loop_father->header) | |
1590 | set_loop_copy (bb->loop_father, NULL); | |
1591 | ||
30e432bb | 1592 | BITMAP_FREE (local_info.duplicate_blocks); |
1593 | local_info.duplicate_blocks = NULL; | |
1594 | ||
388d1fc1 | 1595 | /* Indicate to our caller whether or not any jumps were threaded. */ |
1596 | return local_info.jumps_threaded; | |
a8046f60 | 1597 | } |
1598 | ||
ed4feca1 | 1599 | /* Wrapper for thread_block_1 so that we can first handle jump |
1600 | thread paths which do not involve copying joiner blocks, then | |
1601 | handle jump thread paths which have joiner blocks. | |
1602 | ||
1603 | By doing things this way we can be as aggressive as possible and | |
1604 | not worry that copying a joiner block will create a jump threading | |
1605 | opportunity. */ | |
1b83778e | 1606 | |
ed4feca1 | 1607 | static bool |
1608 | thread_block (basic_block bb, bool noloop_only) | |
1609 | { | |
1610 | bool retval; | |
1611 | retval = thread_block_1 (bb, noloop_only, false); | |
1612 | retval |= thread_block_1 (bb, noloop_only, true); | |
1613 | return retval; | |
1614 | } | |
1615 | ||
1616 | ||
eb31063a | 1617 | /* Threads edge E through E->dest to the edge THREAD_TARGET (E). Returns the |
1618 | copy of E->dest created during threading, or E->dest if it was not necessary | |
7e0311ae | 1619 | to copy it (E is its single predecessor). */ |
1620 | ||
1621 | static basic_block | |
1622 | thread_single_edge (edge e) | |
1623 | { | |
1624 | basic_block bb = e->dest; | |
7e0311ae | 1625 | struct redirection_data rd; |
f2981b08 | 1626 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1627 | edge eto = (*path)[1]->e; | |
7e0311ae | 1628 | |
32b97880 | 1629 | delete_jump_thread_path (path); |
7e0311ae | 1630 | e->aux = NULL; |
1631 | ||
1632 | thread_stats.num_threaded_edges++; | |
1633 | ||
1634 | if (single_pred_p (bb)) | |
1635 | { | |
1636 | /* If BB has just a single predecessor, we should only remove the | |
1637 | control statements at its end, and successors except for ETO. */ | |
1638 | remove_ctrl_stmt_and_useless_edges (bb, eto->dest); | |
ad330780 | 1639 | |
1640 | /* And fixup the flags on the single remaining edge. */ | |
1641 | eto->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL); | |
1642 | eto->flags |= EDGE_FALLTHRU; | |
1643 | ||
7e0311ae | 1644 | return bb; |
1645 | } | |
1646 | ||
1647 | /* Otherwise, we need to create a copy. */ | |
42b013bc | 1648 | if (e->dest == eto->src) |
1649 | update_bb_profile_for_threading (bb, EDGE_FREQUENCY (e), e->count, eto); | |
7e0311ae | 1650 | |
5fe6149c | 1651 | vec<jump_thread_edge *> *npath = new vec<jump_thread_edge *> (); |
1652 | jump_thread_edge *x = new jump_thread_edge (e, EDGE_START_JUMP_THREAD); | |
1653 | npath->safe_push (x); | |
1654 | ||
1655 | x = new jump_thread_edge (eto, EDGE_COPY_SRC_BLOCK); | |
1656 | npath->safe_push (x); | |
1657 | rd.path = npath; | |
7e0311ae | 1658 | |
a7ee7309 | 1659 | create_block_for_threading (bb, &rd, 0, NULL); |
11af02d8 | 1660 | remove_ctrl_stmt_and_useless_edges (rd.dup_blocks[0], NULL); |
1b83c31b | 1661 | create_edge_and_update_destination_phis (&rd, rd.dup_blocks[0], 0); |
7e0311ae | 1662 | |
1663 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1664 | fprintf (dump_file, " Threaded jump %d --> %d to %d\n", | |
11af02d8 | 1665 | e->src->index, e->dest->index, rd.dup_blocks[0]->index); |
7e0311ae | 1666 | |
11af02d8 | 1667 | rd.dup_blocks[0]->count = e->count; |
1668 | rd.dup_blocks[0]->frequency = EDGE_FREQUENCY (e); | |
1669 | single_succ_edge (rd.dup_blocks[0])->count = e->count; | |
1670 | redirect_edge_and_branch (e, rd.dup_blocks[0]); | |
7e0311ae | 1671 | flush_pending_stmts (e); |
1672 | ||
32b97880 | 1673 | delete_jump_thread_path (npath); |
11af02d8 | 1674 | return rd.dup_blocks[0]; |
7e0311ae | 1675 | } |
1676 | ||
1677 | /* Callback for dfs_enumerate_from. Returns true if BB is different | |
1678 | from STOP and DBDS_CE_STOP. */ | |
1679 | ||
1680 | static basic_block dbds_ce_stop; | |
1681 | static bool | |
7ecb5bb2 | 1682 | dbds_continue_enumeration_p (const_basic_block bb, const void *stop) |
7e0311ae | 1683 | { |
7ecb5bb2 | 1684 | return (bb != (const_basic_block) stop |
7e0311ae | 1685 | && bb != dbds_ce_stop); |
1686 | } | |
1687 | ||
1688 | /* Evaluates the dominance relationship of latch of the LOOP and BB, and | |
1689 | returns the state. */ | |
1690 | ||
1691 | enum bb_dom_status | |
1692 | { | |
1693 | /* BB does not dominate latch of the LOOP. */ | |
1694 | DOMST_NONDOMINATING, | |
1695 | /* The LOOP is broken (there is no path from the header to its latch. */ | |
1696 | DOMST_LOOP_BROKEN, | |
1697 | /* BB dominates the latch of the LOOP. */ | |
1698 | DOMST_DOMINATING | |
1699 | }; | |
1700 | ||
1701 | static enum bb_dom_status | |
1702 | determine_bb_domination_status (struct loop *loop, basic_block bb) | |
1703 | { | |
1704 | basic_block *bblocks; | |
1705 | unsigned nblocks, i; | |
1706 | bool bb_reachable = false; | |
1707 | edge_iterator ei; | |
1708 | edge e; | |
1709 | ||
42b013bc | 1710 | /* This function assumes BB is a successor of LOOP->header. |
1711 | If that is not the case return DOMST_NONDOMINATING which | |
1712 | is always safe. */ | |
7e0311ae | 1713 | { |
1714 | bool ok = false; | |
1715 | ||
1716 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1717 | { | |
1718 | if (e->src == loop->header) | |
1719 | { | |
1720 | ok = true; | |
1721 | break; | |
1722 | } | |
1723 | } | |
1724 | ||
42b013bc | 1725 | if (!ok) |
1726 | return DOMST_NONDOMINATING; | |
7e0311ae | 1727 | } |
7e0311ae | 1728 | |
1729 | if (bb == loop->latch) | |
1730 | return DOMST_DOMINATING; | |
1731 | ||
1732 | /* Check that BB dominates LOOP->latch, and that it is back-reachable | |
1733 | from it. */ | |
1734 | ||
1735 | bblocks = XCNEWVEC (basic_block, loop->num_nodes); | |
1736 | dbds_ce_stop = loop->header; | |
1737 | nblocks = dfs_enumerate_from (loop->latch, 1, dbds_continue_enumeration_p, | |
1738 | bblocks, loop->num_nodes, bb); | |
1739 | for (i = 0; i < nblocks; i++) | |
1740 | FOR_EACH_EDGE (e, ei, bblocks[i]->preds) | |
1741 | { | |
1742 | if (e->src == loop->header) | |
1743 | { | |
1744 | free (bblocks); | |
1745 | return DOMST_NONDOMINATING; | |
1746 | } | |
1747 | if (e->src == bb) | |
1748 | bb_reachable = true; | |
1749 | } | |
1750 | ||
1751 | free (bblocks); | |
1752 | return (bb_reachable ? DOMST_DOMINATING : DOMST_LOOP_BROKEN); | |
1753 | } | |
1754 | ||
6eb99d8a | 1755 | /* Return true if BB is part of the new pre-header that is created |
1756 | when threading the latch to DATA. */ | |
1757 | ||
1758 | static bool | |
1759 | def_split_header_continue_p (const_basic_block bb, const void *data) | |
1760 | { | |
1761 | const_basic_block new_header = (const_basic_block) data; | |
a934d302 | 1762 | const struct loop *l; |
1763 | ||
1764 | if (bb == new_header | |
1765 | || loop_depth (bb->loop_father) < loop_depth (new_header->loop_father)) | |
1766 | return false; | |
1767 | for (l = bb->loop_father; l; l = loop_outer (l)) | |
1768 | if (l == new_header->loop_father) | |
1769 | return true; | |
1770 | return false; | |
6eb99d8a | 1771 | } |
1772 | ||
7e0311ae | 1773 | /* Thread jumps through the header of LOOP. Returns true if cfg changes. |
1774 | If MAY_PEEL_LOOP_HEADERS is false, we avoid threading from entry edges | |
1775 | to the inside of the loop. */ | |
1776 | ||
1777 | static bool | |
1778 | thread_through_loop_header (struct loop *loop, bool may_peel_loop_headers) | |
1779 | { | |
1780 | basic_block header = loop->header; | |
1781 | edge e, tgt_edge, latch = loop_latch_edge (loop); | |
1782 | edge_iterator ei; | |
1783 | basic_block tgt_bb, atgt_bb; | |
1784 | enum bb_dom_status domst; | |
1785 | ||
1786 | /* We have already threaded through headers to exits, so all the threading | |
1787 | requests now are to the inside of the loop. We need to avoid creating | |
1788 | irreducible regions (i.e., loops with more than one entry block), and | |
1789 | also loop with several latch edges, or new subloops of the loop (although | |
1790 | there are cases where it might be appropriate, it is difficult to decide, | |
1791 | and doing it wrongly may confuse other optimizers). | |
1792 | ||
1793 | We could handle more general cases here. However, the intention is to | |
1794 | preserve some information about the loop, which is impossible if its | |
1795 | structure changes significantly, in a way that is not well understood. | |
1796 | Thus we only handle few important special cases, in which also updating | |
1797 | of the loop-carried information should be feasible: | |
1798 | ||
1799 | 1) Propagation of latch edge to a block that dominates the latch block | |
1800 | of a loop. This aims to handle the following idiom: | |
1801 | ||
1802 | first = 1; | |
1803 | while (1) | |
1804 | { | |
1805 | if (first) | |
1806 | initialize; | |
1807 | first = 0; | |
1808 | body; | |
1809 | } | |
1810 | ||
1811 | After threading the latch edge, this becomes | |
1812 | ||
1813 | first = 1; | |
1814 | if (first) | |
1815 | initialize; | |
1816 | while (1) | |
1817 | { | |
1818 | first = 0; | |
1819 | body; | |
1820 | } | |
1821 | ||
1822 | The original header of the loop is moved out of it, and we may thread | |
1823 | the remaining edges through it without further constraints. | |
1824 | ||
1825 | 2) All entry edges are propagated to a single basic block that dominates | |
1826 | the latch block of the loop. This aims to handle the following idiom | |
1827 | (normally created for "for" loops): | |
1828 | ||
1829 | i = 0; | |
1830 | while (1) | |
1831 | { | |
1832 | if (i >= 100) | |
1833 | break; | |
1834 | body; | |
1835 | i++; | |
1836 | } | |
1837 | ||
1838 | This becomes | |
1839 | ||
1840 | i = 0; | |
1841 | while (1) | |
1842 | { | |
1843 | body; | |
1844 | i++; | |
1845 | if (i >= 100) | |
1846 | break; | |
1847 | } | |
1848 | */ | |
1849 | ||
1850 | /* Threading through the header won't improve the code if the header has just | |
1851 | one successor. */ | |
1852 | if (single_succ_p (header)) | |
1853 | goto fail; | |
1854 | ||
98685018 | 1855 | /* If we threaded the latch using a joiner block, we cancel the |
1856 | threading opportunity out of an abundance of caution. However, | |
1857 | still allow threading from outside to inside the loop. */ | |
7e0311ae | 1858 | if (latch->aux) |
1859 | { | |
f2981b08 | 1860 | vec<jump_thread_edge *> *path = THREAD_PATH (latch); |
1861 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
98685018 | 1862 | { |
1863 | delete_jump_thread_path (path); | |
1864 | latch->aux = NULL; | |
1865 | } | |
1866 | } | |
1867 | ||
1868 | if (latch->aux) | |
1869 | { | |
1870 | vec<jump_thread_edge *> *path = THREAD_PATH (latch); | |
f2981b08 | 1871 | tgt_edge = (*path)[1]->e; |
7e0311ae | 1872 | tgt_bb = tgt_edge->dest; |
1873 | } | |
1874 | else if (!may_peel_loop_headers | |
1875 | && !redirection_block_p (loop->header)) | |
1876 | goto fail; | |
1877 | else | |
1878 | { | |
1879 | tgt_bb = NULL; | |
1880 | tgt_edge = NULL; | |
1881 | FOR_EACH_EDGE (e, ei, header->preds) | |
1882 | { | |
1883 | if (!e->aux) | |
1884 | { | |
1885 | if (e == latch) | |
1886 | continue; | |
1887 | ||
1888 | /* If latch is not threaded, and there is a header | |
1889 | edge that is not threaded, we would create loop | |
1890 | with multiple entries. */ | |
1891 | goto fail; | |
1892 | } | |
1893 | ||
f2981b08 | 1894 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1895 | ||
1896 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
da81e0c5 | 1897 | goto fail; |
f2981b08 | 1898 | tgt_edge = (*path)[1]->e; |
7e0311ae | 1899 | atgt_bb = tgt_edge->dest; |
1900 | if (!tgt_bb) | |
1901 | tgt_bb = atgt_bb; | |
1902 | /* Two targets of threading would make us create loop | |
1903 | with multiple entries. */ | |
1904 | else if (tgt_bb != atgt_bb) | |
1905 | goto fail; | |
1906 | } | |
1907 | ||
1908 | if (!tgt_bb) | |
1909 | { | |
1910 | /* There are no threading requests. */ | |
1911 | return false; | |
1912 | } | |
1913 | ||
1914 | /* Redirecting to empty loop latch is useless. */ | |
1915 | if (tgt_bb == loop->latch | |
1916 | && empty_block_p (loop->latch)) | |
1917 | goto fail; | |
1918 | } | |
1919 | ||
1920 | /* The target block must dominate the loop latch, otherwise we would be | |
1921 | creating a subloop. */ | |
1922 | domst = determine_bb_domination_status (loop, tgt_bb); | |
1923 | if (domst == DOMST_NONDOMINATING) | |
1924 | goto fail; | |
1925 | if (domst == DOMST_LOOP_BROKEN) | |
1926 | { | |
1927 | /* If the loop ceased to exist, mark it as such, and thread through its | |
1928 | original header. */ | |
d25159cc | 1929 | mark_loop_for_removal (loop); |
7e0311ae | 1930 | return thread_block (header, false); |
1931 | } | |
1932 | ||
1933 | if (tgt_bb->loop_father->header == tgt_bb) | |
1934 | { | |
1935 | /* If the target of the threading is a header of a subloop, we need | |
1936 | to create a preheader for it, so that the headers of the two loops | |
1937 | do not merge. */ | |
1938 | if (EDGE_COUNT (tgt_bb->preds) > 2) | |
1939 | { | |
1940 | tgt_bb = create_preheader (tgt_bb->loop_father, 0); | |
1941 | gcc_assert (tgt_bb != NULL); | |
1942 | } | |
1943 | else | |
1944 | tgt_bb = split_edge (tgt_edge); | |
1945 | } | |
48e1416a | 1946 | |
7e0311ae | 1947 | if (latch->aux) |
1948 | { | |
6eb99d8a | 1949 | basic_block *bblocks; |
1950 | unsigned nblocks, i; | |
1951 | ||
35c67c83 | 1952 | /* First handle the case latch edge is redirected. We are copying |
559685be | 1953 | the loop header but not creating a multiple entry loop. Make the |
35c67c83 | 1954 | cfg manipulation code aware of that fact. */ |
1955 | set_loop_copy (loop, loop); | |
7e0311ae | 1956 | loop->latch = thread_single_edge (latch); |
35c67c83 | 1957 | set_loop_copy (loop, NULL); |
7e0311ae | 1958 | gcc_assert (single_succ (loop->latch) == tgt_bb); |
1959 | loop->header = tgt_bb; | |
1960 | ||
6eb99d8a | 1961 | /* Remove the new pre-header blocks from our loop. */ |
1962 | bblocks = XCNEWVEC (basic_block, loop->num_nodes); | |
1963 | nblocks = dfs_enumerate_from (header, 0, def_split_header_continue_p, | |
1964 | bblocks, loop->num_nodes, tgt_bb); | |
1965 | for (i = 0; i < nblocks; i++) | |
c99897b6 | 1966 | if (bblocks[i]->loop_father == loop) |
1967 | { | |
1968 | remove_bb_from_loops (bblocks[i]); | |
1969 | add_bb_to_loop (bblocks[i], loop_outer (loop)); | |
1970 | } | |
6eb99d8a | 1971 | free (bblocks); |
1972 | ||
bb722af4 | 1973 | /* If the new header has multiple latches mark it so. */ |
1974 | FOR_EACH_EDGE (e, ei, loop->header->preds) | |
1975 | if (e->src->loop_father == loop | |
1976 | && e->src != loop->latch) | |
1977 | { | |
1978 | loop->latch = NULL; | |
1979 | loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES); | |
1980 | } | |
1981 | ||
6eb99d8a | 1982 | /* Cancel remaining threading requests that would make the |
1983 | loop a multiple entry loop. */ | |
1984 | FOR_EACH_EDGE (e, ei, header->preds) | |
1985 | { | |
1986 | edge e2; | |
bb722af4 | 1987 | |
6eb99d8a | 1988 | if (e->aux == NULL) |
1989 | continue; | |
1990 | ||
f2981b08 | 1991 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1992 | e2 = path->last ()->e; | |
6eb99d8a | 1993 | |
1994 | if (e->src->loop_father != e2->dest->loop_father | |
1995 | && e2->dest != loop->header) | |
1996 | { | |
6d1fdbf9 | 1997 | delete_jump_thread_path (path); |
6eb99d8a | 1998 | e->aux = NULL; |
1999 | } | |
2000 | } | |
2001 | ||
7e0311ae | 2002 | /* Thread the remaining edges through the former header. */ |
2003 | thread_block (header, false); | |
2004 | } | |
2005 | else | |
2006 | { | |
2007 | basic_block new_preheader; | |
2008 | ||
2009 | /* Now consider the case entry edges are redirected to the new entry | |
2010 | block. Remember one entry edge, so that we can find the new | |
eb31063a | 2011 | preheader (its destination after threading). */ |
7e0311ae | 2012 | FOR_EACH_EDGE (e, ei, header->preds) |
2013 | { | |
2014 | if (e->aux) | |
2015 | break; | |
2016 | } | |
2017 | ||
2018 | /* The duplicate of the header is the new preheader of the loop. Ensure | |
2019 | that it is placed correctly in the loop hierarchy. */ | |
96c90e5e | 2020 | set_loop_copy (loop, loop_outer (loop)); |
7e0311ae | 2021 | |
2022 | thread_block (header, false); | |
96c90e5e | 2023 | set_loop_copy (loop, NULL); |
7e0311ae | 2024 | new_preheader = e->dest; |
2025 | ||
2026 | /* Create the new latch block. This is always necessary, as the latch | |
2027 | must have only a single successor, but the original header had at | |
2028 | least two successors. */ | |
2029 | loop->latch = NULL; | |
2030 | mfb_kj_edge = single_succ_edge (new_preheader); | |
2031 | loop->header = mfb_kj_edge->dest; | |
2032 | latch = make_forwarder_block (tgt_bb, mfb_keep_just, NULL); | |
2033 | loop->header = latch->dest; | |
2034 | loop->latch = latch->src; | |
2035 | } | |
48e1416a | 2036 | |
7e0311ae | 2037 | return true; |
2038 | ||
2039 | fail: | |
2040 | /* We failed to thread anything. Cancel the requests. */ | |
2041 | FOR_EACH_EDGE (e, ei, header->preds) | |
2042 | { | |
f2981b08 | 2043 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
2044 | ||
2045 | if (path) | |
2046 | { | |
6d1fdbf9 | 2047 | delete_jump_thread_path (path); |
f2981b08 | 2048 | e->aux = NULL; |
2049 | } | |
7e0311ae | 2050 | } |
2051 | return false; | |
2052 | } | |
2053 | ||
b99a7d6d | 2054 | /* E1 and E2 are edges into the same basic block. Return TRUE if the |
2055 | PHI arguments associated with those edges are equal or there are no | |
2056 | PHI arguments, otherwise return FALSE. */ | |
2057 | ||
2058 | static bool | |
2059 | phi_args_equal_on_edges (edge e1, edge e2) | |
2060 | { | |
1a91d914 | 2061 | gphi_iterator gsi; |
b99a7d6d | 2062 | int indx1 = e1->dest_idx; |
2063 | int indx2 = e2->dest_idx; | |
2064 | ||
2065 | for (gsi = gsi_start_phis (e1->dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
2066 | { | |
1a91d914 | 2067 | gphi *phi = gsi.phi (); |
b99a7d6d | 2068 | |
2069 | if (!operand_equal_p (gimple_phi_arg_def (phi, indx1), | |
2070 | gimple_phi_arg_def (phi, indx2), 0)) | |
2071 | return false; | |
2072 | } | |
2073 | return true; | |
2074 | } | |
2075 | ||
3cebc9d2 | 2076 | /* Walk through the registered jump threads and convert them into a |
334ec2d8 | 2077 | form convenient for this pass. |
3cebc9d2 | 2078 | |
2079 | Any block which has incoming edges threaded to outgoing edges | |
2080 | will have its entry in THREADED_BLOCK set. | |
a8046f60 | 2081 | |
3cebc9d2 | 2082 | Any threaded edge will have its new outgoing edge stored in the |
2083 | original edge's AUX field. | |
a8046f60 | 2084 | |
3cebc9d2 | 2085 | This form avoids the need to walk all the edges in the CFG to |
2086 | discover blocks which need processing and avoids unnecessary | |
2087 | hash table lookups to map from threaded edge to new target. */ | |
a8046f60 | 2088 | |
3cebc9d2 | 2089 | static void |
2090 | mark_threaded_blocks (bitmap threaded_blocks) | |
2091 | { | |
2092 | unsigned int i; | |
7e0311ae | 2093 | bitmap_iterator bi; |
2094 | bitmap tmp = BITMAP_ALLOC (NULL); | |
2095 | basic_block bb; | |
2096 | edge e; | |
2097 | edge_iterator ei; | |
3cebc9d2 | 2098 | |
b93ba654 | 2099 | /* It is possible to have jump threads in which one is a subpath |
2100 | of the other. ie, (A, B), (B, C), (C, D) where B is a joiner | |
2101 | block and (B, C), (C, D) where no joiner block exists. | |
2102 | ||
2103 | When this occurs ignore the jump thread request with the joiner | |
2104 | block. It's totally subsumed by the simpler jump thread request. | |
2105 | ||
2106 | This results in less block copying, simpler CFGs. More importantly, | |
2107 | when we duplicate the joiner block, B, in this case we will create | |
2108 | a new threading opportunity that we wouldn't be able to optimize | |
2109 | until the next jump threading iteration. | |
2110 | ||
2111 | So first convert the jump thread requests which do not require a | |
2112 | joiner block. */ | |
f2981b08 | 2113 | for (i = 0; i < paths.length (); i++) |
3cebc9d2 | 2114 | { |
f2981b08 | 2115 | vec<jump_thread_edge *> *path = paths[i]; |
b93ba654 | 2116 | |
2117 | if ((*path)[1]->type != EDGE_COPY_SRC_JOINER_BLOCK) | |
2118 | { | |
2119 | edge e = (*path)[0]->e; | |
2120 | e->aux = (void *)path; | |
2121 | bitmap_set_bit (tmp, e->dest->index); | |
2122 | } | |
1f3976e7 | 2123 | } |
2124 | ||
b93ba654 | 2125 | /* Now iterate again, converting cases where we want to thread |
2126 | through a joiner block, but only if no other edge on the path | |
f1ce4e72 | 2127 | already has a jump thread attached to it. We do this in two passes, |
2128 | to avoid situations where the order in the paths vec can hide overlapping | |
2129 | threads (the path is recorded on the incoming edge, so we would miss | |
2130 | cases where the second path starts at a downstream edge on the same | |
2131 | path). First record all joiner paths, deleting any in the unexpected | |
2132 | case where there is already a path for that incoming edge. */ | |
51ea8bc6 | 2133 | for (i = 0; i < paths.length ();) |
b93ba654 | 2134 | { |
2135 | vec<jump_thread_edge *> *path = paths[i]; | |
2136 | ||
2137 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
9943b198 | 2138 | { |
f1ce4e72 | 2139 | /* Attach the path to the starting edge if none is yet recorded. */ |
9943b198 | 2140 | if ((*path)[0]->e->aux == NULL) |
5d293e79 | 2141 | { |
9943b198 | 2142 | (*path)[0]->e->aux = path; |
51ea8bc6 | 2143 | i++; |
5d293e79 | 2144 | } |
2145 | else | |
2146 | { | |
2147 | paths.unordered_remove (i); | |
2148 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
9943b198 | 2149 | dump_jump_thread_path (dump_file, *path, false); |
5d293e79 | 2150 | delete_jump_thread_path (path); |
2151 | } | |
9943b198 | 2152 | } |
51ea8bc6 | 2153 | else |
2154 | { | |
2155 | i++; | |
2156 | } | |
f1ce4e72 | 2157 | } |
51ea8bc6 | 2158 | |
f1ce4e72 | 2159 | /* Second, look for paths that have any other jump thread attached to |
2160 | them, and either finish converting them or cancel them. */ | |
51ea8bc6 | 2161 | for (i = 0; i < paths.length ();) |
f1ce4e72 | 2162 | { |
2163 | vec<jump_thread_edge *> *path = paths[i]; | |
2164 | edge e = (*path)[0]->e; | |
2165 | ||
2166 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK && e->aux == path) | |
b93ba654 | 2167 | { |
2168 | unsigned int j; | |
f1ce4e72 | 2169 | for (j = 1; j < path->length (); j++) |
b93ba654 | 2170 | if ((*path)[j]->e->aux != NULL) |
2171 | break; | |
2172 | ||
2173 | /* If we iterated through the entire path without exiting the loop, | |
f1ce4e72 | 2174 | then we are good to go, record it. */ |
b93ba654 | 2175 | if (j == path->length ()) |
51ea8bc6 | 2176 | { |
2177 | bitmap_set_bit (tmp, e->dest->index); | |
2178 | i++; | |
2179 | } | |
f1ce4e72 | 2180 | else |
b93ba654 | 2181 | { |
f1ce4e72 | 2182 | e->aux = NULL; |
5d293e79 | 2183 | paths.unordered_remove (i); |
f1ce4e72 | 2184 | if (dump_file && (dump_flags & TDF_DETAILS)) |
9943b198 | 2185 | dump_jump_thread_path (dump_file, *path, false); |
5d293e79 | 2186 | delete_jump_thread_path (path); |
b93ba654 | 2187 | } |
2188 | } | |
51ea8bc6 | 2189 | else |
2190 | { | |
2191 | i++; | |
2192 | } | |
b93ba654 | 2193 | } |
b99a7d6d | 2194 | |
7e0311ae | 2195 | /* If optimizing for size, only thread through block if we don't have |
2196 | to duplicate it or it's an otherwise empty redirection block. */ | |
0bfd8d5c | 2197 | if (optimize_function_for_size_p (cfun)) |
7e0311ae | 2198 | { |
2199 | EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
2200 | { | |
f5a6b05f | 2201 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
7e0311ae | 2202 | if (EDGE_COUNT (bb->preds) > 1 |
2203 | && !redirection_block_p (bb)) | |
2204 | { | |
2205 | FOR_EACH_EDGE (e, ei, bb->preds) | |
eb31063a | 2206 | { |
f2981b08 | 2207 | if (e->aux) |
2208 | { | |
2209 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
6d1fdbf9 | 2210 | delete_jump_thread_path (path); |
f2981b08 | 2211 | e->aux = NULL; |
2212 | } | |
eb31063a | 2213 | } |
7e0311ae | 2214 | } |
2215 | else | |
2216 | bitmap_set_bit (threaded_blocks, i); | |
2217 | } | |
3cebc9d2 | 2218 | } |
7e0311ae | 2219 | else |
2220 | bitmap_copy (threaded_blocks, tmp); | |
2221 | ||
6328e25d | 2222 | /* Look for jump threading paths which cross multiple loop headers. |
2223 | ||
2224 | The code to thread through loop headers will change the CFG in ways | |
2225 | that break assumptions made by the loop optimization code. | |
2226 | ||
2227 | We don't want to blindly cancel the requests. We can instead do better | |
2228 | by trimming off the end of the jump thread path. */ | |
2229 | EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
2230 | { | |
f5a6b05f | 2231 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); |
6328e25d | 2232 | FOR_EACH_EDGE (e, ei, bb->preds) |
2233 | { | |
2234 | if (e->aux) | |
2235 | { | |
2236 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
2237 | ||
de9b51e4 | 2238 | for (unsigned int i = 0, crossed_headers = 0; |
2239 | i < path->length (); | |
2240 | i++) | |
6328e25d | 2241 | { |
de9b51e4 | 2242 | basic_block dest = (*path)[i]->e->dest; |
2243 | crossed_headers += (dest == dest->loop_father->header); | |
2244 | if (crossed_headers > 1) | |
6328e25d | 2245 | { |
de9b51e4 | 2246 | /* Trim from entry I onwards. */ |
2247 | for (unsigned int j = i; j < path->length (); j++) | |
2248 | delete (*path)[j]; | |
2249 | path->truncate (i); | |
2250 | ||
2251 | /* Now that we've truncated the path, make sure | |
2252 | what's left is still valid. We need at least | |
2253 | two edges on the path and the last edge can not | |
2254 | be a joiner. This should never happen, but let's | |
2255 | be safe. */ | |
2256 | if (path->length () < 2 | |
2257 | || (path->last ()->type | |
2258 | == EDGE_COPY_SRC_JOINER_BLOCK)) | |
6328e25d | 2259 | { |
de9b51e4 | 2260 | delete_jump_thread_path (path); |
2261 | e->aux = NULL; | |
6328e25d | 2262 | } |
de9b51e4 | 2263 | break; |
6328e25d | 2264 | } |
2265 | } | |
2266 | } | |
2267 | } | |
2268 | } | |
2269 | ||
af6b6631 | 2270 | /* If we have a joiner block (J) which has two successors S1 and S2 and |
2271 | we are threading though S1 and the final destination of the thread | |
2272 | is S2, then we must verify that any PHI nodes in S2 have the same | |
2273 | PHI arguments for the edge J->S2 and J->S1->...->S2. | |
2274 | ||
2275 | We used to detect this prior to registering the jump thread, but | |
2276 | that prohibits propagation of edge equivalences into non-dominated | |
2277 | PHI nodes as the equivalency test might occur before propagation. | |
2278 | ||
2279 | This must also occur after we truncate any jump threading paths | |
2280 | as this scenario may only show up after truncation. | |
2281 | ||
2282 | This works for now, but will need improvement as part of the FSA | |
2283 | optimization. | |
2284 | ||
2285 | Note since we've moved the thread request data to the edges, | |
2286 | we have to iterate on those rather than the threaded_edges vector. */ | |
2287 | EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
2288 | { | |
f5a6b05f | 2289 | bb = BASIC_BLOCK_FOR_FN (cfun, i); |
af6b6631 | 2290 | FOR_EACH_EDGE (e, ei, bb->preds) |
2291 | { | |
2292 | if (e->aux) | |
2293 | { | |
2294 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
2295 | bool have_joiner = ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK); | |
2296 | ||
2297 | if (have_joiner) | |
2298 | { | |
2299 | basic_block joiner = e->dest; | |
2300 | edge final_edge = path->last ()->e; | |
2301 | basic_block final_dest = final_edge->dest; | |
2302 | edge e2 = find_edge (joiner, final_dest); | |
2303 | ||
2304 | if (e2 && !phi_args_equal_on_edges (e2, final_edge)) | |
2305 | { | |
2306 | delete_jump_thread_path (path); | |
2307 | e->aux = NULL; | |
2308 | } | |
2309 | } | |
2310 | } | |
2311 | } | |
2312 | } | |
2313 | ||
9af5ce0c | 2314 | BITMAP_FREE (tmp); |
3cebc9d2 | 2315 | } |
2316 | ||
2317 | ||
ab596744 | 2318 | /* Return TRUE if BB ends with a switch statement or a computed goto. |
2319 | Otherwise return false. */ | |
2320 | static bool | |
2321 | bb_ends_with_multiway_branch (basic_block bb ATTRIBUTE_UNUSED) | |
2322 | { | |
42acab1c | 2323 | gimple *stmt = last_stmt (bb); |
ab596744 | 2324 | if (stmt && gimple_code (stmt) == GIMPLE_SWITCH) |
2325 | return true; | |
2326 | if (stmt && gimple_code (stmt) == GIMPLE_GOTO | |
2327 | && TREE_CODE (gimple_goto_dest (stmt)) == SSA_NAME) | |
2328 | return true; | |
2329 | return false; | |
2330 | } | |
2331 | ||
9e0d85a7 | 2332 | /* Verify that the REGION is a valid jump thread. A jump thread is a special |
2333 | case of SEME Single Entry Multiple Exits region in which all nodes in the | |
2334 | REGION have exactly one incoming edge. The only exception is the first block | |
2335 | that may not have been connected to the rest of the cfg yet. */ | |
ded1c768 | 2336 | |
2337 | DEBUG_FUNCTION void | |
9e0d85a7 | 2338 | verify_jump_thread (basic_block *region, unsigned n_region) |
ded1c768 | 2339 | { |
ded1c768 | 2340 | for (unsigned i = 0; i < n_region; i++) |
9e0d85a7 | 2341 | gcc_assert (EDGE_COUNT (region[i]->preds) <= 1); |
2342 | } | |
ded1c768 | 2343 | |
9e0d85a7 | 2344 | /* Return true when BB is one of the first N items in BBS. */ |
ded1c768 | 2345 | |
9e0d85a7 | 2346 | static inline bool |
2347 | bb_in_bbs (basic_block bb, basic_block *bbs, int n) | |
2348 | { | |
2349 | for (int i = 0; i < n; i++) | |
2350 | if (bb == bbs[i]) | |
2351 | return true; | |
ded1c768 | 2352 | |
9e0d85a7 | 2353 | return false; |
ded1c768 | 2354 | } |
2355 | ||
9e0d85a7 | 2356 | /* Duplicates a jump-thread path of N_REGION basic blocks. |
2357 | The ENTRY edge is redirected to the duplicate of the region. | |
ded1c768 | 2358 | |
2359 | Remove the last conditional statement in the last basic block in the REGION, | |
2360 | and create a single fallthru edge pointing to the same destination as the | |
2361 | EXIT edge. | |
2362 | ||
2363 | The new basic blocks are stored to REGION_COPY in the same order as they had | |
2364 | in REGION, provided that REGION_COPY is not NULL. | |
2365 | ||
2366 | Returns false if it is unable to copy the region, true otherwise. */ | |
2367 | ||
2368 | static bool | |
9e0d85a7 | 2369 | duplicate_thread_path (edge entry, edge exit, |
ded1c768 | 2370 | basic_block *region, unsigned n_region, |
2371 | basic_block *region_copy) | |
2372 | { | |
2373 | unsigned i; | |
af5f6a93 | 2374 | bool free_region_copy = false; |
ded1c768 | 2375 | struct loop *loop = entry->dest->loop_father; |
2376 | edge exit_copy; | |
2377 | edge redirected; | |
2378 | int total_freq = 0, entry_freq = 0; | |
2379 | gcov_type total_count = 0, entry_count = 0; | |
2380 | ||
2381 | if (!can_copy_bbs_p (region, n_region)) | |
2382 | return false; | |
2383 | ||
2384 | /* Some sanity checking. Note that we do not check for all possible | |
2385 | missuses of the functions. I.e. if you ask to copy something weird, | |
2386 | it will work, but the state of structures probably will not be | |
2387 | correct. */ | |
2388 | for (i = 0; i < n_region; i++) | |
2389 | { | |
2390 | /* We do not handle subloops, i.e. all the blocks must belong to the | |
2391 | same loop. */ | |
2392 | if (region[i]->loop_father != loop) | |
2393 | return false; | |
2394 | } | |
2395 | ||
2396 | initialize_original_copy_tables (); | |
2397 | ||
af5f6a93 | 2398 | set_loop_copy (loop, loop); |
ded1c768 | 2399 | |
2400 | if (!region_copy) | |
2401 | { | |
2402 | region_copy = XNEWVEC (basic_block, n_region); | |
2403 | free_region_copy = true; | |
2404 | } | |
2405 | ||
2406 | if (entry->dest->count) | |
2407 | { | |
2408 | total_count = entry->dest->count; | |
2409 | entry_count = entry->count; | |
2410 | /* Fix up corner cases, to avoid division by zero or creation of negative | |
2411 | frequencies. */ | |
2412 | if (entry_count > total_count) | |
2413 | entry_count = total_count; | |
2414 | } | |
2415 | else | |
2416 | { | |
2417 | total_freq = entry->dest->frequency; | |
2418 | entry_freq = EDGE_FREQUENCY (entry); | |
2419 | /* Fix up corner cases, to avoid division by zero or creation of negative | |
2420 | frequencies. */ | |
2421 | if (total_freq == 0) | |
2422 | total_freq = 1; | |
2423 | else if (entry_freq > total_freq) | |
2424 | entry_freq = total_freq; | |
2425 | } | |
2426 | ||
2427 | copy_bbs (region, n_region, region_copy, &exit, 1, &exit_copy, loop, | |
9e0d85a7 | 2428 | split_edge_bb_loc (entry), false); |
2429 | ||
2430 | /* Fix up: copy_bbs redirects all edges pointing to copied blocks. The | |
2431 | following code ensures that all the edges exiting the jump-thread path are | |
2432 | redirected back to the original code: these edges are exceptions | |
2433 | invalidating the property that is propagated by executing all the blocks of | |
2434 | the jump-thread path in order. */ | |
2435 | ||
2436 | for (i = 0; i < n_region; i++) | |
2437 | { | |
2438 | edge e; | |
2439 | edge_iterator ei; | |
2440 | basic_block bb = region_copy[i]; | |
2441 | ||
2442 | if (single_succ_p (bb)) | |
2443 | { | |
2444 | /* Make sure the successor is the next node in the path. */ | |
2445 | gcc_assert (i + 1 == n_region | |
2446 | || region_copy[i + 1] == single_succ_edge (bb)->dest); | |
2447 | continue; | |
2448 | } | |
2449 | ||
2450 | /* Special case the last block on the path: make sure that it does not | |
2451 | jump back on the copied path. */ | |
2452 | if (i + 1 == n_region) | |
2453 | { | |
2454 | FOR_EACH_EDGE (e, ei, bb->succs) | |
2455 | if (bb_in_bbs (e->dest, region_copy, n_region - 1)) | |
2456 | { | |
2457 | basic_block orig = get_bb_original (e->dest); | |
2458 | if (orig) | |
2459 | redirect_edge_and_branch_force (e, orig); | |
2460 | } | |
2461 | continue; | |
2462 | } | |
2463 | ||
2464 | /* Redirect all other edges jumping to non-adjacent blocks back to the | |
2465 | original code. */ | |
2466 | FOR_EACH_EDGE (e, ei, bb->succs) | |
2467 | if (region_copy[i + 1] != e->dest) | |
2468 | { | |
2469 | basic_block orig = get_bb_original (e->dest); | |
2470 | if (orig) | |
2471 | redirect_edge_and_branch_force (e, orig); | |
2472 | } | |
2473 | } | |
2474 | ||
ded1c768 | 2475 | if (total_count) |
2476 | { | |
2477 | scale_bbs_frequencies_gcov_type (region, n_region, | |
2478 | total_count - entry_count, | |
2479 | total_count); | |
2480 | scale_bbs_frequencies_gcov_type (region_copy, n_region, entry_count, | |
2481 | total_count); | |
2482 | } | |
2483 | else | |
2484 | { | |
2485 | scale_bbs_frequencies_int (region, n_region, total_freq - entry_freq, | |
2486 | total_freq); | |
2487 | scale_bbs_frequencies_int (region_copy, n_region, entry_freq, total_freq); | |
2488 | } | |
2489 | ||
2490 | #ifdef ENABLE_CHECKING | |
9e0d85a7 | 2491 | verify_jump_thread (region_copy, n_region); |
ded1c768 | 2492 | #endif |
2493 | ||
2494 | /* Remove the last branch in the jump thread path. */ | |
2495 | remove_ctrl_stmt_and_useless_edges (region_copy[n_region - 1], exit->dest); | |
7729459f | 2496 | |
2497 | /* And fixup the flags on the single remaining edge. */ | |
2498 | edge fix_e = find_edge (region_copy[n_region - 1], exit->dest); | |
2499 | fix_e->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL); | |
2500 | fix_e->flags |= EDGE_FALLTHRU; | |
2501 | ||
ded1c768 | 2502 | edge e = make_edge (region_copy[n_region - 1], exit->dest, EDGE_FALLTHRU); |
2503 | ||
2504 | if (e) { | |
2505 | rescan_loop_exit (e, true, false); | |
2506 | e->probability = REG_BR_PROB_BASE; | |
2507 | e->count = region_copy[n_region - 1]->count; | |
2508 | } | |
2509 | ||
2510 | /* Redirect the entry and add the phi node arguments. */ | |
af5f6a93 | 2511 | if (entry->dest == loop->header) |
2512 | mark_loop_for_removal (loop); | |
ded1c768 | 2513 | redirected = redirect_edge_and_branch (entry, get_bb_copy (entry->dest)); |
2514 | gcc_assert (redirected != NULL); | |
2515 | flush_pending_stmts (entry); | |
2516 | ||
2517 | /* Add the other PHI node arguments. */ | |
2518 | add_phi_args_after_copy (region_copy, n_region, NULL); | |
2519 | ||
2520 | if (free_region_copy) | |
2521 | free (region_copy); | |
2522 | ||
2523 | free_original_copy_tables (); | |
2524 | return true; | |
2525 | } | |
2526 | ||
b9903eb3 | 2527 | /* Return true when PATH is a valid jump-thread path. */ |
2528 | ||
2529 | static bool | |
2530 | valid_jump_thread_path (vec<jump_thread_edge *> *path) | |
2531 | { | |
2532 | unsigned len = path->length (); | |
2533 | ||
2534 | /* Check that the path is connected. */ | |
2535 | for (unsigned int j = 0; j < len - 1; j++) | |
2536 | if ((*path)[j]->e->dest != (*path)[j+1]->e->src) | |
2537 | return false; | |
2538 | ||
2539 | return true; | |
2540 | } | |
2541 | ||
f1344f45 | 2542 | /* Remove any queued jump threads that start at BB. */ |
2543 | ||
2544 | void | |
2545 | remove_jump_threads_starting_at (basic_block bb) | |
2546 | { | |
2547 | if (!paths.exists ()) | |
2548 | return; | |
2549 | ||
2550 | for (unsigned i = 0; i < paths.length ();) | |
2551 | { | |
2552 | vec<jump_thread_edge *> *path = paths[i]; | |
2553 | ||
2554 | /* Sadly, FSM jump threads have a slightly different | |
2555 | representation than the rest of the jump threads. */ | |
2556 | if ((*path)[0]->type == EDGE_FSM_THREAD | |
2557 | && (*path)[0]->e->src == bb) | |
2558 | { | |
2559 | delete_jump_thread_path (path); | |
2560 | paths.unordered_remove (i); | |
2561 | } | |
2562 | else if ((*path)[0]->type != EDGE_FSM_THREAD | |
2563 | && (*path)[0]->e->dest == bb) | |
2564 | { | |
2565 | delete_jump_thread_path (path); | |
2566 | paths.unordered_remove (i); | |
2567 | } | |
2568 | else | |
2569 | i++; | |
2570 | } | |
2571 | } | |
2572 | ||
3cebc9d2 | 2573 | /* Walk through all blocks and thread incoming edges to the appropriate |
2574 | outgoing edge for each edge pair recorded in THREADED_EDGES. | |
a8046f60 | 2575 | |
2576 | It is the caller's responsibility to fix the dominance information | |
2577 | and rewrite duplicated SSA_NAMEs back into SSA form. | |
2578 | ||
7e0311ae | 2579 | If MAY_PEEL_LOOP_HEADERS is false, we avoid threading edges through |
2580 | loop headers if it does not simplify the loop. | |
2581 | ||
dac49aa5 | 2582 | Returns true if one or more edges were threaded, false otherwise. */ |
a8046f60 | 2583 | |
2584 | bool | |
7e0311ae | 2585 | thread_through_all_blocks (bool may_peel_loop_headers) |
a8046f60 | 2586 | { |
a8046f60 | 2587 | bool retval = false; |
7ea47fbd | 2588 | unsigned int i; |
2589 | bitmap_iterator bi; | |
3cebc9d2 | 2590 | bitmap threaded_blocks; |
7e0311ae | 2591 | struct loop *loop; |
3cebc9d2 | 2592 | |
f2981b08 | 2593 | if (!paths.exists ()) |
3cebc9d2 | 2594 | return false; |
a8046f60 | 2595 | |
3cebc9d2 | 2596 | threaded_blocks = BITMAP_ALLOC (NULL); |
5236b8bb | 2597 | memset (&thread_stats, 0, sizeof (thread_stats)); |
388d1fc1 | 2598 | |
ded1c768 | 2599 | /* Jump-thread all FSM threads before other jump-threads. */ |
2600 | for (i = 0; i < paths.length ();) | |
2601 | { | |
2602 | vec<jump_thread_edge *> *path = paths[i]; | |
2603 | edge entry = (*path)[0]->e; | |
2604 | ||
b9903eb3 | 2605 | /* Only code-generate FSM jump-threads in this loop. */ |
2606 | if ((*path)[0]->type != EDGE_FSM_THREAD) | |
2607 | { | |
2608 | i++; | |
2609 | continue; | |
2610 | } | |
2611 | ||
2612 | /* Do not jump-thread twice from the same block. */ | |
2613 | if (bitmap_bit_p (threaded_blocks, entry->src->index) | |
2614 | /* Verify that the jump thread path is still valid: a | |
2615 | previous jump-thread may have changed the CFG, and | |
2616 | invalidated the current path. */ | |
2617 | || !valid_jump_thread_path (path)) | |
2618 | { | |
2619 | /* Remove invalid FSM jump-thread paths. */ | |
2620 | delete_jump_thread_path (path); | |
2621 | paths.unordered_remove (i); | |
2622 | continue; | |
2623 | } | |
ded1c768 | 2624 | |
2625 | unsigned len = path->length (); | |
2626 | edge exit = (*path)[len - 1]->e; | |
2627 | basic_block *region = XNEWVEC (basic_block, len - 1); | |
2628 | ||
2629 | for (unsigned int j = 0; j < len - 1; j++) | |
2630 | region[j] = (*path)[j]->e->dest; | |
2631 | ||
9e0d85a7 | 2632 | if (duplicate_thread_path (entry, exit, region, len - 1, NULL)) |
ded1c768 | 2633 | { |
2634 | /* We do not update dominance info. */ | |
2635 | free_dominance_info (CDI_DOMINATORS); | |
2636 | bitmap_set_bit (threaded_blocks, entry->src->index); | |
2637 | retval = true; | |
2638 | } | |
2639 | ||
2640 | delete_jump_thread_path (path); | |
2641 | paths.unordered_remove (i); | |
2642 | } | |
2643 | ||
2644 | /* Remove from PATHS all the jump-threads starting with an edge already | |
2645 | jump-threaded. */ | |
2646 | for (i = 0; i < paths.length ();) | |
2647 | { | |
2648 | vec<jump_thread_edge *> *path = paths[i]; | |
2649 | edge entry = (*path)[0]->e; | |
2650 | ||
2651 | /* Do not jump-thread twice from the same block. */ | |
2652 | if (bitmap_bit_p (threaded_blocks, entry->src->index)) | |
2653 | { | |
2654 | delete_jump_thread_path (path); | |
2655 | paths.unordered_remove (i); | |
2656 | } | |
2657 | else | |
2658 | i++; | |
2659 | } | |
2660 | ||
2661 | bitmap_clear (threaded_blocks); | |
2662 | ||
3cebc9d2 | 2663 | mark_threaded_blocks (threaded_blocks); |
2664 | ||
96c90e5e | 2665 | initialize_original_copy_tables (); |
7e0311ae | 2666 | |
2667 | /* First perform the threading requests that do not affect | |
2668 | loop structure. */ | |
7ea47fbd | 2669 | EXECUTE_IF_SET_IN_BITMAP (threaded_blocks, 0, i, bi) |
a8046f60 | 2670 | { |
f5a6b05f | 2671 | basic_block bb = BASIC_BLOCK_FOR_FN (cfun, i); |
7ea47fbd | 2672 | |
2673 | if (EDGE_COUNT (bb->preds) > 0) | |
7e0311ae | 2674 | retval |= thread_block (bb, true); |
2675 | } | |
2676 | ||
2677 | /* Then perform the threading through loop headers. We start with the | |
2678 | innermost loop, so that the changes in cfg we perform won't affect | |
2679 | further threading. */ | |
f21d4d00 | 2680 | FOR_EACH_LOOP (loop, LI_FROM_INNERMOST) |
7e0311ae | 2681 | { |
7a3bf727 | 2682 | if (!loop->header |
2683 | || !bitmap_bit_p (threaded_blocks, loop->header->index)) | |
2684 | continue; | |
7e0311ae | 2685 | |
7a3bf727 | 2686 | retval |= thread_through_loop_header (loop, may_peel_loop_headers); |
a8046f60 | 2687 | } |
388d1fc1 | 2688 | |
ab596744 | 2689 | /* Any jump threading paths that are still attached to edges at this |
2690 | point must be one of two cases. | |
2691 | ||
2692 | First, we could have a jump threading path which went from outside | |
2693 | a loop to inside a loop that was ignored because a prior jump thread | |
2694 | across a backedge was realized (which indirectly causes the loop | |
2695 | above to ignore the latter thread). We can detect these because the | |
2696 | loop structures will be different and we do not currently try to | |
2697 | optimize this case. | |
2698 | ||
2699 | Second, we could be threading across a backedge to a point within the | |
2700 | same loop. This occurrs for the FSA/FSM optimization and we would | |
2701 | like to optimize it. However, we have to be very careful as this | |
2702 | may completely scramble the loop structures, with the result being | |
2703 | irreducible loops causing us to throw away our loop structure. | |
2704 | ||
2705 | As a compromise for the latter case, if the thread path ends in | |
2706 | a block where the last statement is a multiway branch, then go | |
2707 | ahead and thread it, else ignore it. */ | |
ed4feca1 | 2708 | basic_block bb; |
ed4feca1 | 2709 | edge e; |
fc00614f | 2710 | FOR_EACH_BB_FN (bb, cfun) |
ed4feca1 | 2711 | { |
ab596744 | 2712 | /* If we do end up threading here, we can remove elements from |
2713 | BB->preds. Thus we can not use the FOR_EACH_EDGE iterator. */ | |
2714 | for (edge_iterator ei = ei_start (bb->preds); | |
2715 | (e = ei_safe_edge (ei));) | |
ed4feca1 | 2716 | if (e->aux) |
2717 | { | |
2718 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
2719 | ||
ab596744 | 2720 | /* Case 1, threading from outside to inside the loop |
2721 | after we'd already threaded through the header. */ | |
2722 | if ((*path)[0]->e->dest->loop_father | |
2723 | != path->last ()->e->src->loop_father) | |
2724 | { | |
2725 | delete_jump_thread_path (path); | |
2726 | e->aux = NULL; | |
2727 | ei_next (&ei); | |
2728 | } | |
2729 | else if (bb_ends_with_multiway_branch (path->last ()->e->src)) | |
2730 | { | |
2731 | /* The code to thread through loop headers may have | |
2732 | split a block with jump threads attached to it. | |
2733 | ||
2734 | We can identify this with a disjoint jump threading | |
2735 | path. If found, just remove it. */ | |
2736 | for (unsigned int i = 0; i < path->length () - 1; i++) | |
2737 | if ((*path)[i]->e->dest != (*path)[i + 1]->e->src) | |
2738 | { | |
2739 | delete_jump_thread_path (path); | |
2740 | e->aux = NULL; | |
2741 | ei_next (&ei); | |
2742 | break; | |
2743 | } | |
2744 | ||
2745 | /* Our path is still valid, thread it. */ | |
9943b198 | 2746 | if (e->aux) |
ab596744 | 2747 | { |
d2644aa0 | 2748 | if (thread_block ((*path)[0]->e->dest, false)) |
addf6c7a | 2749 | e->aux = NULL; |
d2644aa0 | 2750 | else |
2751 | { | |
9943b198 | 2752 | delete_jump_thread_path (path); |
d2644aa0 | 2753 | e->aux = NULL; |
2754 | ei_next (&ei); | |
2755 | } | |
ab596744 | 2756 | } |
2757 | } | |
2758 | else | |
2759 | { | |
2760 | delete_jump_thread_path (path); | |
2761 | e->aux = NULL; | |
2762 | ei_next (&ei); | |
2763 | } | |
ed4feca1 | 2764 | } |
ab596744 | 2765 | else |
2766 | ei_next (&ei); | |
ed4feca1 | 2767 | } |
2768 | ||
581f8050 | 2769 | statistics_counter_event (cfun, "Jumps threaded", |
2770 | thread_stats.num_threaded_edges); | |
5236b8bb | 2771 | |
96c90e5e | 2772 | free_original_copy_tables (); |
2773 | ||
3cebc9d2 | 2774 | BITMAP_FREE (threaded_blocks); |
2775 | threaded_blocks = NULL; | |
f2981b08 | 2776 | paths.release (); |
7e0311ae | 2777 | |
396c773e | 2778 | if (retval) |
f24ec26f | 2779 | loops_state_set (LOOPS_NEED_FIXUP); |
eb2a640e | 2780 | |
a8046f60 | 2781 | return retval; |
2782 | } | |
3cebc9d2 | 2783 | |
6d1fdbf9 | 2784 | /* Delete the jump threading path PATH. We have to explcitly delete |
2785 | each entry in the vector, then the container. */ | |
2786 | ||
2787 | void | |
2788 | delete_jump_thread_path (vec<jump_thread_edge *> *path) | |
2789 | { | |
2790 | for (unsigned int i = 0; i < path->length (); i++) | |
2791 | delete (*path)[i]; | |
2792 | path->release(); | |
9b5a88db | 2793 | delete path; |
6d1fdbf9 | 2794 | } |
2795 | ||
3cebc9d2 | 2796 | /* Register a jump threading opportunity. We queue up all the jump |
2797 | threading opportunities discovered by a pass and update the CFG | |
2798 | and SSA form all at once. | |
2799 | ||
f0b5f617 | 2800 | E is the edge we can thread, E2 is the new target edge, i.e., we |
3cebc9d2 | 2801 | are effectively recording that E->dest can be changed to E2->dest |
2802 | after fixing the SSA graph. */ | |
2803 | ||
2804 | void | |
f2981b08 | 2805 | register_jump_thread (vec<jump_thread_edge *> *path) |
3cebc9d2 | 2806 | { |
a3724f9d | 2807 | if (!dbg_cnt (registered_jump_thread)) |
2808 | { | |
6d1fdbf9 | 2809 | delete_jump_thread_path (path); |
a3724f9d | 2810 | return; |
2811 | } | |
2812 | ||
0c5b289a | 2813 | /* First make sure there are no NULL outgoing edges on the jump threading |
2814 | path. That can happen for jumping to a constant address. */ | |
f2981b08 | 2815 | for (unsigned int i = 0; i < path->length (); i++) |
2816 | if ((*path)[i]->e == NULL) | |
0c5b289a | 2817 | { |
2818 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
2819 | { | |
2820 | fprintf (dump_file, | |
2821 | "Found NULL edge in jump threading path. Cancelling jump thread:\n"); | |
b93ba654 | 2822 | dump_jump_thread_path (dump_file, *path, false); |
0c5b289a | 2823 | } |
f2981b08 | 2824 | |
6d1fdbf9 | 2825 | delete_jump_thread_path (path); |
0c5b289a | 2826 | return; |
2827 | } | |
5411af4e | 2828 | |
631d940c | 2829 | if (dump_file && (dump_flags & TDF_DETAILS)) |
b93ba654 | 2830 | dump_jump_thread_path (dump_file, *path, true); |
631d940c | 2831 | |
f2981b08 | 2832 | if (!paths.exists ()) |
2833 | paths.create (5); | |
631d940c | 2834 | |
f2981b08 | 2835 | paths.safe_push (path); |
3cebc9d2 | 2836 | } |