]>
Commit | Line | Data |
---|---|---|
56b043c8 | 1 | /* Thread edges through blocks and update the control flow and SSA graphs. |
d1e082c2 | 2 | Copyright (C) 2004-2013 Free Software Foundation, Inc. |
56b043c8 JL |
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 | |
9dcd6f09 | 8 | the Free Software Foundation; either version 3, or (at your option) |
56b043c8 JL |
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 | |
9dcd6f09 NC |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
56b043c8 JL |
19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
56b043c8 JL |
23 | #include "tree.h" |
24 | #include "flags.h" | |
56b043c8 | 25 | #include "basic-block.h" |
56b043c8 | 26 | #include "function.h" |
442b4905 AM |
27 | #include "gimple.h" |
28 | #include "gimple-ssa.h" | |
29 | #include "tree-phinodes.h" | |
7a300452 | 30 | #include "tree-ssa.h" |
5254eac4 | 31 | #include "tree-ssa-threadupdate.h" |
7ee2468b | 32 | #include "dumpfile.h" |
d38ffc55 | 33 | #include "cfgloop.h" |
0823efed | 34 | #include "hash-table.h" |
01e127b1 | 35 | #include "dbgcnt.h" |
56b043c8 JL |
36 | |
37 | /* Given a block B, update the CFG and SSA graph to reflect redirecting | |
38 | one or more in-edges to B to instead reach the destination of an | |
39 | out-edge from B while preserving any side effects in B. | |
40 | ||
454ff5cb | 41 | i.e., given A->B and B->C, change A->B to be A->C yet still preserve the |
56b043c8 JL |
42 | side effects of executing B. |
43 | ||
44 | 1. Make a copy of B (including its outgoing edges and statements). Call | |
45 | the copy B'. Note B' has no incoming edges or PHIs at this time. | |
46 | ||
47 | 2. Remove the control statement at the end of B' and all outgoing edges | |
48 | except B'->C. | |
49 | ||
50 | 3. Add a new argument to each PHI in C with the same value as the existing | |
51 | argument associated with edge B->C. Associate the new PHI arguments | |
52 | with the edge B'->C. | |
53 | ||
54 | 4. For each PHI in B, find or create a PHI in B' with an identical | |
d4a9b3a3 | 55 | PHI_RESULT. Add an argument to the PHI in B' which has the same |
56b043c8 JL |
56 | value as the PHI in B associated with the edge A->B. Associate |
57 | the new argument in the PHI in B' with the edge A->B. | |
58 | ||
59 | 5. Change the edge A->B to A->B'. | |
60 | ||
61 | 5a. This automatically deletes any PHI arguments associated with the | |
62 | edge A->B in B. | |
63 | ||
64 | 5b. This automatically associates each new argument added in step 4 | |
65 | with the edge A->B'. | |
66 | ||
67 | 6. Repeat for other incoming edges into B. | |
68 | ||
69 | 7. Put the duplicated resources in B and all the B' blocks into SSA form. | |
70 | ||
71 | Note that block duplication can be minimized by first collecting the | |
fa10beec | 72 | set of unique destination blocks that the incoming edges should |
633c9126 JL |
73 | be threaded to. |
74 | ||
aee2d611 | 75 | Block duplication can be further minimized by using B instead of |
633c9126 JL |
76 | creating B' for one destination if all edges into B are going to be |
77 | threaded to a successor of B. We had code to do this at one time, but | |
78 | I'm not convinced it is correct with the changes to avoid mucking up | |
79 | the loop structure (which may cancel threading requests, thus a block | |
80 | which we thought was going to become unreachable may still be reachable). | |
81 | This code was also going to get ugly with the introduction of the ability | |
aee2d611 | 82 | for a single jump thread request to bypass multiple blocks. |
56b043c8 | 83 | |
1983ac12 JL |
84 | We further reduce the number of edges and statements we create by |
85 | not copying all the outgoing edges and the control statement in | |
86 | step #1. We instead create a template block without the outgoing | |
87 | edges and duplicate the template. */ | |
88 | ||
89 | ||
90 | /* Steps #5 and #6 of the above algorithm are best implemented by walking | |
91 | all the incoming edges which thread to the same destination edge at | |
92 | the same time. That avoids lots of table lookups to get information | |
93 | for the destination edge. | |
94 | ||
95 | To realize that implementation we create a list of incoming edges | |
96 | which thread to the same outgoing edge. Thus to implement steps | |
97 | #5 and #6 we traverse our hash table of outgoing edge information. | |
98 | For each entry we walk the list of incoming edges which thread to | |
99 | the current outgoing edge. */ | |
100 | ||
101 | struct el | |
102 | { | |
103 | edge e; | |
104 | struct el *next; | |
105 | }; | |
56b043c8 JL |
106 | |
107 | /* Main data structure recording information regarding B's duplicate | |
108 | blocks. */ | |
109 | ||
1983ac12 JL |
110 | /* We need to efficiently record the unique thread destinations of this |
111 | block and specific information associated with those destinations. We | |
112 | may have many incoming edges threaded to the same outgoing edge. This | |
e7a531ae | 113 | can be naturally implemented with a hash table. */ |
1983ac12 | 114 | |
5deac340 | 115 | struct redirection_data : typed_free_remove<redirection_data> |
56b043c8 JL |
116 | { |
117 | /* A duplicate of B with the trailing control statement removed and which | |
118 | targets a single successor of B. */ | |
119 | basic_block dup_block; | |
120 | ||
1465e5cf JL |
121 | /* The jump threading path. */ |
122 | vec<jump_thread_edge *> *path; | |
1983ac12 | 123 | |
1465e5cf JL |
124 | /* A list of incoming edges which we want to thread to the |
125 | same path. */ | |
1983ac12 | 126 | struct el *incoming_edges; |
5deac340 RG |
127 | |
128 | /* hash_table support. */ | |
5831a5f0 LC |
129 | typedef redirection_data value_type; |
130 | typedef redirection_data compare_type; | |
131 | static inline hashval_t hash (const value_type *); | |
132 | static inline int equal (const value_type *, const compare_type *); | |
56b043c8 JL |
133 | }; |
134 | ||
1465e5cf JL |
135 | /* Simple hashing function. For any given incoming edge E, we're going |
136 | to be most concerned with the final destination of its jump thread | |
137 | path. So hash on the block index of the final edge in the path. */ | |
138 | ||
5deac340 | 139 | inline hashval_t |
5831a5f0 | 140 | redirection_data::hash (const value_type *p) |
5deac340 | 141 | { |
1465e5cf JL |
142 | vec<jump_thread_edge *> *path = p->path; |
143 | return path->last ()->e->dest->index; | |
5deac340 RG |
144 | } |
145 | ||
1465e5cf JL |
146 | /* Given two hash table entries, return true if they have the same |
147 | jump threading path. */ | |
5deac340 | 148 | inline int |
5831a5f0 | 149 | redirection_data::equal (const value_type *p1, const compare_type *p2) |
5deac340 | 150 | { |
1465e5cf JL |
151 | vec<jump_thread_edge *> *path1 = p1->path; |
152 | vec<jump_thread_edge *> *path2 = p2->path; | |
153 | ||
154 | if (path1->length () != path2->length ()) | |
155 | return false; | |
156 | ||
157 | for (unsigned int i = 1; i < path1->length (); i++) | |
158 | { | |
159 | if ((*path1)[i]->type != (*path2)[i]->type | |
160 | || (*path1)[i]->e != (*path2)[i]->e) | |
161 | return false; | |
162 | } | |
163 | ||
164 | return true; | |
5deac340 RG |
165 | } |
166 | ||
1983ac12 | 167 | /* Data structure of information to pass to hash table traversal routines. */ |
0823efed | 168 | struct ssa_local_info_t |
1983ac12 JL |
169 | { |
170 | /* The current block we are working on. */ | |
171 | basic_block bb; | |
172 | ||
173 | /* A template copy of BB with no outgoing edges or control statement that | |
174 | we use for creating copies. */ | |
175 | basic_block template_block; | |
d38ffc55 JL |
176 | |
177 | /* TRUE if we thread one or more jumps, FALSE otherwise. */ | |
178 | bool jumps_threaded; | |
1983ac12 | 179 | }; |
37840132 | 180 | |
8702a557 JL |
181 | /* Passes which use the jump threading code register jump threading |
182 | opportunities as they are discovered. We keep the registered | |
183 | jump threading opportunities in this vector as edge pairs | |
184 | (original_edge, target_edge). */ | |
aee2d611 | 185 | static vec<vec<jump_thread_edge *> *> paths; |
8702a557 | 186 | |
7134c090 JL |
187 | /* When we start updating the CFG for threading, data necessary for jump |
188 | threading is attached to the AUX field for the incoming edge. Use these | |
189 | macros to access the underlying structure attached to the AUX field. */ | |
aee2d611 | 190 | #define THREAD_PATH(E) ((vec<jump_thread_edge *> *)(E)->aux) |
8702a557 | 191 | |
a4233c29 DN |
192 | /* Jump threading statistics. */ |
193 | ||
194 | struct thread_stats_d | |
195 | { | |
196 | unsigned long num_threaded_edges; | |
197 | }; | |
198 | ||
199 | struct thread_stats_d thread_stats; | |
200 | ||
201 | ||
e376fe58 JL |
202 | /* Remove the last statement in block BB if it is a control statement |
203 | Also remove all outgoing edges except the edge which reaches DEST_BB. | |
204 | If DEST_BB is NULL, then remove all outgoing edges. */ | |
56b043c8 JL |
205 | |
206 | static void | |
e376fe58 | 207 | remove_ctrl_stmt_and_useless_edges (basic_block bb, basic_block dest_bb) |
56b043c8 | 208 | { |
726a989a | 209 | gimple_stmt_iterator gsi; |
628f6a4e BE |
210 | edge e; |
211 | edge_iterator ei; | |
56b043c8 | 212 | |
726a989a | 213 | gsi = gsi_last_bb (bb); |
56b043c8 | 214 | |
e376fe58 | 215 | /* If the duplicate ends with a control statement, then remove it. |
56b043c8 | 216 | |
e376fe58 JL |
217 | Note that if we are duplicating the template block rather than the |
218 | original basic block, then the duplicate might not have any real | |
219 | statements in it. */ | |
726a989a RB |
220 | if (!gsi_end_p (gsi) |
221 | && gsi_stmt (gsi) | |
222 | && (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND | |
223 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_GOTO | |
224 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_SWITCH)) | |
225 | gsi_remove (&gsi, true); | |
56b043c8 | 226 | |
628f6a4e | 227 | for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); ) |
56b043c8 | 228 | { |
56b043c8 | 229 | if (e->dest != dest_bb) |
d0d2cc21 | 230 | remove_edge (e); |
628f6a4e BE |
231 | else |
232 | ei_next (&ei); | |
56b043c8 | 233 | } |
56b043c8 JL |
234 | } |
235 | ||
a91926b9 | 236 | /* Create a duplicate of BB. Record the duplicate block in RD. */ |
56b043c8 JL |
237 | |
238 | static void | |
239 | create_block_for_threading (basic_block bb, struct redirection_data *rd) | |
240 | { | |
7134c090 JL |
241 | edge_iterator ei; |
242 | edge e; | |
243 | ||
56b043c8 JL |
244 | /* We can use the generic block duplication code and simply remove |
245 | the stuff we do not need. */ | |
b9a66240 | 246 | rd->dup_block = duplicate_block (bb, NULL, NULL); |
56b043c8 | 247 | |
7134c090 JL |
248 | FOR_EACH_EDGE (e, ei, rd->dup_block->succs) |
249 | e->aux = NULL; | |
250 | ||
15db5571 JH |
251 | /* Zero out the profile, since the block is unreachable for now. */ |
252 | rd->dup_block->frequency = 0; | |
253 | rd->dup_block->count = 0; | |
56b043c8 JL |
254 | } |
255 | ||
0823efed DN |
256 | /* Main data structure to hold information for duplicates of BB. */ |
257 | ||
5deac340 | 258 | static hash_table <redirection_data> redirection_data; |
0823efed | 259 | |
1983ac12 JL |
260 | /* Given an outgoing edge E lookup and return its entry in our hash table. |
261 | ||
262 | If INSERT is true, then we insert the entry into the hash table if | |
263 | it is not already present. INCOMING_EDGE is added to the list of incoming | |
264 | edges associated with E in the hash table. */ | |
265 | ||
266 | static struct redirection_data * | |
361b51c0 | 267 | lookup_redirection_data (edge e, enum insert_option insert) |
1983ac12 | 268 | { |
0823efed | 269 | struct redirection_data **slot; |
1983ac12 | 270 | struct redirection_data *elt; |
aee2d611 | 271 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1983ac12 JL |
272 | |
273 | /* Build a hash table element so we can see if E is already | |
274 | in the table. */ | |
5ed6ace5 | 275 | elt = XNEW (struct redirection_data); |
1465e5cf | 276 | elt->path = path; |
1983ac12 | 277 | elt->dup_block = NULL; |
1983ac12 JL |
278 | elt->incoming_edges = NULL; |
279 | ||
0823efed | 280 | slot = redirection_data.find_slot (elt, insert); |
1983ac12 JL |
281 | |
282 | /* This will only happen if INSERT is false and the entry is not | |
283 | in the hash table. */ | |
284 | if (slot == NULL) | |
285 | { | |
286 | free (elt); | |
287 | return NULL; | |
288 | } | |
289 | ||
290 | /* This will only happen if E was not in the hash table and | |
291 | INSERT is true. */ | |
292 | if (*slot == NULL) | |
293 | { | |
0823efed | 294 | *slot = elt; |
5ed6ace5 | 295 | elt->incoming_edges = XNEW (struct el); |
361b51c0 | 296 | elt->incoming_edges->e = e; |
1983ac12 JL |
297 | elt->incoming_edges->next = NULL; |
298 | return elt; | |
299 | } | |
300 | /* E was in the hash table. */ | |
301 | else | |
302 | { | |
303 | /* Free ELT as we do not need it anymore, we will extract the | |
304 | relevant entry from the hash table itself. */ | |
305 | free (elt); | |
306 | ||
307 | /* Get the entry stored in the hash table. */ | |
0823efed | 308 | elt = *slot; |
1983ac12 JL |
309 | |
310 | /* If insertion was requested, then we need to add INCOMING_EDGE | |
311 | to the list of incoming edges associated with E. */ | |
312 | if (insert) | |
313 | { | |
5ed6ace5 | 314 | struct el *el = XNEW (struct el); |
1983ac12 | 315 | el->next = elt->incoming_edges; |
361b51c0 | 316 | el->e = e; |
1983ac12 JL |
317 | elt->incoming_edges = el; |
318 | } | |
319 | ||
320 | return elt; | |
321 | } | |
322 | } | |
323 | ||
361b51c0 JL |
324 | /* For each PHI in BB, copy the argument associated with SRC_E to TGT_E. */ |
325 | ||
326 | static void | |
327 | copy_phi_args (basic_block bb, edge src_e, edge tgt_e) | |
328 | { | |
329 | gimple_stmt_iterator gsi; | |
330 | int src_indx = src_e->dest_idx; | |
331 | ||
332 | for (gsi = gsi_start_phis (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
333 | { | |
334 | gimple phi = gsi_stmt (gsi); | |
335 | source_location locus = gimple_phi_arg_location (phi, src_indx); | |
9e227d60 | 336 | add_phi_arg (phi, gimple_phi_arg_def (phi, src_indx), tgt_e, locus); |
361b51c0 JL |
337 | } |
338 | } | |
339 | ||
340 | /* We have recently made a copy of ORIG_BB, including its outgoing | |
341 | edges. The copy is NEW_BB. Every PHI node in every direct successor of | |
342 | ORIG_BB has a new argument associated with edge from NEW_BB to the | |
343 | successor. Initialize the PHI argument so that it is equal to the PHI | |
344 | argument associated with the edge from ORIG_BB to the successor. */ | |
345 | ||
346 | static void | |
347 | update_destination_phis (basic_block orig_bb, basic_block new_bb) | |
348 | { | |
349 | edge_iterator ei; | |
350 | edge e; | |
351 | ||
352 | FOR_EACH_EDGE (e, ei, orig_bb->succs) | |
353 | { | |
354 | edge e2 = find_edge (new_bb, e->dest); | |
355 | copy_phi_args (e->dest, e, e2); | |
356 | } | |
357 | } | |
358 | ||
1983ac12 JL |
359 | /* Given a duplicate block and its single destination (both stored |
360 | in RD). Create an edge between the duplicate and its single | |
361 | destination. | |
362 | ||
363 | Add an additional argument to any PHI nodes at the single | |
364 | destination. */ | |
365 | ||
366 | static void | |
520af9ec JL |
367 | create_edge_and_update_destination_phis (struct redirection_data *rd, |
368 | basic_block bb) | |
1983ac12 | 369 | { |
1465e5cf | 370 | edge e = make_edge (bb, rd->path->last ()->e->dest, EDGE_FALLTHRU); |
1983ac12 | 371 | |
aa2645a0 | 372 | rescan_loop_exit (e, true, false); |
d416304e | 373 | e->probability = REG_BR_PROB_BASE; |
520af9ec | 374 | e->count = bb->count; |
7134c090 | 375 | |
aee2d611 JL |
376 | /* We have to copy path -- which means creating a new vector as well |
377 | as all the jump_thread_edge entries. */ | |
1465e5cf | 378 | if (rd->path->last ()->e->aux) |
7134c090 | 379 | { |
1465e5cf | 380 | vec<jump_thread_edge *> *path = THREAD_PATH (rd->path->last ()->e); |
aee2d611 JL |
381 | vec<jump_thread_edge *> *copy = new vec<jump_thread_edge *> (); |
382 | ||
383 | /* Sadly, the elements of the vector are pointers and need to | |
384 | be copied as well. */ | |
385 | for (unsigned int i = 0; i < path->length (); i++) | |
386 | { | |
387 | jump_thread_edge *x | |
388 | = new jump_thread_edge ((*path)[i]->e, (*path)[i]->type); | |
389 | copy->safe_push (x); | |
390 | } | |
391 | e->aux = (void *)copy; | |
7134c090 JL |
392 | } |
393 | else | |
394 | { | |
395 | e->aux = NULL; | |
396 | } | |
d416304e | 397 | |
1983ac12 JL |
398 | /* If there are any PHI nodes at the destination of the outgoing edge |
399 | from the duplicate block, then we will need to add a new argument | |
400 | to them. The argument should have the same value as the argument | |
401 | associated with the outgoing edge stored in RD. */ | |
1465e5cf | 402 | copy_phi_args (e->dest, rd->path->last ()->e, e); |
361b51c0 JL |
403 | } |
404 | ||
405 | /* Wire up the outgoing edges from the duplicate block and | |
406 | update any PHIs as needed. */ | |
0823efed DN |
407 | void |
408 | ssa_fix_duplicate_block_edges (struct redirection_data *rd, | |
409 | ssa_local_info_t *local_info) | |
361b51c0 | 410 | { |
aee2d611 JL |
411 | edge e = rd->incoming_edges->e; |
412 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
413 | ||
361b51c0 JL |
414 | /* If we were threading through an joiner block, then we want |
415 | to keep its control statement and redirect an outgoing edge. | |
416 | Else we want to remove the control statement & edges, then create | |
417 | a new outgoing edge. In both cases we may need to update PHIs. */ | |
aee2d611 | 418 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) |
1983ac12 | 419 | { |
361b51c0 JL |
420 | edge victim; |
421 | edge e2; | |
361b51c0 JL |
422 | |
423 | /* This updates the PHIs at the destination of the duplicate | |
424 | block. */ | |
425 | update_destination_phis (local_info->bb, rd->dup_block); | |
f5045c96 | 426 | |
361b51c0 JL |
427 | /* Find the edge from the duplicate block to the block we're |
428 | threading through. That's the edge we want to redirect. */ | |
aee2d611 JL |
429 | victim = find_edge (rd->dup_block, (*path)[1]->e->dest); |
430 | e2 = redirect_edge_and_branch (victim, path->last ()->e->dest); | |
431 | e2->count = path->last ()->e->count; | |
361b51c0 | 432 | |
ad3577df JL |
433 | /* If we redirected the edge, then we need to copy PHI arguments |
434 | at the target. If the edge already existed (e2 != victim case), | |
435 | then the PHIs in the target already have the correct arguments. */ | |
436 | if (e2 == victim) | |
aee2d611 | 437 | copy_phi_args (e2->dest, path->last ()->e, e2); |
361b51c0 JL |
438 | } |
439 | else | |
440 | { | |
441 | remove_ctrl_stmt_and_useless_edges (rd->dup_block, NULL); | |
442 | create_edge_and_update_destination_phis (rd, rd->dup_block); | |
1983ac12 JL |
443 | } |
444 | } | |
1983ac12 JL |
445 | /* Hash table traversal callback routine to create duplicate blocks. */ |
446 | ||
0823efed DN |
447 | int |
448 | ssa_create_duplicates (struct redirection_data **slot, | |
449 | ssa_local_info_t *local_info) | |
1983ac12 | 450 | { |
0823efed | 451 | struct redirection_data *rd = *slot; |
1983ac12 | 452 | |
1983ac12 JL |
453 | /* Create a template block if we have not done so already. Otherwise |
454 | use the template to create a new block. */ | |
455 | if (local_info->template_block == NULL) | |
456 | { | |
457 | create_block_for_threading (local_info->bb, rd); | |
458 | local_info->template_block = rd->dup_block; | |
459 | ||
460 | /* We do not create any outgoing edges for the template. We will | |
461 | take care of that in a later traversal. That way we do not | |
462 | create edges that are going to just be deleted. */ | |
463 | } | |
464 | else | |
465 | { | |
466 | create_block_for_threading (local_info->template_block, rd); | |
467 | ||
468 | /* Go ahead and wire up outgoing edges and update PHIs for the duplicate | |
361b51c0 | 469 | block. */ |
0823efed | 470 | ssa_fix_duplicate_block_edges (rd, local_info); |
1983ac12 JL |
471 | } |
472 | ||
473 | /* Keep walking the hash table. */ | |
474 | return 1; | |
475 | } | |
476 | ||
477 | /* We did not create any outgoing edges for the template block during | |
478 | block creation. This hash table traversal callback creates the | |
479 | outgoing edge for the template block. */ | |
480 | ||
0823efed DN |
481 | inline int |
482 | ssa_fixup_template_block (struct redirection_data **slot, | |
483 | ssa_local_info_t *local_info) | |
1983ac12 | 484 | { |
0823efed | 485 | struct redirection_data *rd = *slot; |
1983ac12 | 486 | |
361b51c0 JL |
487 | /* If this is the template block halt the traversal after updating |
488 | it appropriately. | |
489 | ||
490 | If we were threading through an joiner block, then we want | |
491 | to keep its control statement and redirect an outgoing edge. | |
492 | Else we want to remove the control statement & edges, then create | |
493 | a new outgoing edge. In both cases we may need to update PHIs. */ | |
1983ac12 JL |
494 | if (rd->dup_block && rd->dup_block == local_info->template_block) |
495 | { | |
0823efed | 496 | ssa_fix_duplicate_block_edges (rd, local_info); |
1983ac12 JL |
497 | return 0; |
498 | } | |
499 | ||
500 | return 1; | |
501 | } | |
502 | ||
503 | /* Hash table traversal callback to redirect each incoming edge | |
504 | associated with this hash table element to its new destination. */ | |
505 | ||
0823efed DN |
506 | int |
507 | ssa_redirect_edges (struct redirection_data **slot, | |
508 | ssa_local_info_t *local_info) | |
1983ac12 | 509 | { |
0823efed | 510 | struct redirection_data *rd = *slot; |
1983ac12 JL |
511 | struct el *next, *el; |
512 | ||
513 | /* Walk over all the incoming edges associated associated with this | |
514 | hash table entry. */ | |
515 | for (el = rd->incoming_edges; el; el = next) | |
516 | { | |
517 | edge e = el->e; | |
aee2d611 | 518 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1983ac12 JL |
519 | |
520 | /* Go ahead and free this element from the list. Doing this now | |
521 | avoids the need for another list walk when we destroy the hash | |
522 | table. */ | |
523 | next = el->next; | |
524 | free (el); | |
525 | ||
a4233c29 DN |
526 | thread_stats.num_threaded_edges++; |
527 | ||
05357ac3 | 528 | if (rd->dup_block) |
1983ac12 JL |
529 | { |
530 | edge e2; | |
531 | ||
532 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
533 | fprintf (dump_file, " Threaded jump %d --> %d to %d\n", | |
534 | e->src->index, e->dest->index, rd->dup_block->index); | |
535 | ||
2b151cb2 | 536 | rd->dup_block->count += e->count; |
0bed228e JH |
537 | |
538 | /* Excessive jump threading may make frequencies large enough so | |
539 | the computation overflows. */ | |
540 | if (rd->dup_block->frequency < BB_FREQ_MAX * 2) | |
541 | rd->dup_block->frequency += EDGE_FREQUENCY (e); | |
05357ac3 TJ |
542 | |
543 | /* In the case of threading through a joiner block, the outgoing | |
544 | edges from the duplicate block were updated when they were | |
545 | redirected during ssa_fix_duplicate_block_edges. */ | |
aee2d611 | 546 | if ((*path)[1]->type != EDGE_COPY_SRC_JOINER_BLOCK) |
05357ac3 TJ |
547 | EDGE_SUCC (rd->dup_block, 0)->count += e->count; |
548 | ||
549 | /* Redirect the incoming edge (possibly to the joiner block) to the | |
550 | appropriate duplicate block. */ | |
1983ac12 | 551 | e2 = redirect_edge_and_branch (e, rd->dup_block); |
b02b9b53 | 552 | gcc_assert (e == e2); |
1983ac12 | 553 | flush_pending_stmts (e2); |
1983ac12 | 554 | } |
7134c090 JL |
555 | |
556 | /* Go ahead and clear E->aux. It's not needed anymore and failure | |
557 | to clear it will cause all kinds of unpleasant problems later. */ | |
aee2d611 JL |
558 | for (unsigned int i = 0; i < path->length (); i++) |
559 | delete (*path)[i]; | |
560 | path->release (); | |
7134c090 JL |
561 | e->aux = NULL; |
562 | ||
1983ac12 | 563 | } |
d38ffc55 JL |
564 | |
565 | /* Indicate that we actually threaded one or more jumps. */ | |
566 | if (rd->incoming_edges) | |
567 | local_info->jumps_threaded = true; | |
568 | ||
1983ac12 JL |
569 | return 1; |
570 | } | |
571 | ||
31a9760a RS |
572 | /* Return true if this block has no executable statements other than |
573 | a simple ctrl flow instruction. When the number of outgoing edges | |
574 | is one, this is equivalent to a "forwarder" block. */ | |
575 | ||
576 | static bool | |
b48d0358 | 577 | redirection_block_p (basic_block bb) |
31a9760a | 578 | { |
726a989a | 579 | gimple_stmt_iterator gsi; |
31a9760a RS |
580 | |
581 | /* Advance to the first executable statement. */ | |
726a989a RB |
582 | gsi = gsi_start_bb (bb); |
583 | while (!gsi_end_p (gsi) | |
584 | && (gimple_code (gsi_stmt (gsi)) == GIMPLE_LABEL | |
b5b8b0ac | 585 | || is_gimple_debug (gsi_stmt (gsi)) |
726a989a RB |
586 | || gimple_nop_p (gsi_stmt (gsi)))) |
587 | gsi_next (&gsi); | |
b8698a0f | 588 | |
31a9760a | 589 | /* Check if this is an empty block. */ |
726a989a | 590 | if (gsi_end_p (gsi)) |
31a9760a RS |
591 | return true; |
592 | ||
593 | /* Test that we've reached the terminating control statement. */ | |
726a989a RB |
594 | return gsi_stmt (gsi) |
595 | && (gimple_code (gsi_stmt (gsi)) == GIMPLE_COND | |
596 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_GOTO | |
597 | || gimple_code (gsi_stmt (gsi)) == GIMPLE_SWITCH); | |
31a9760a RS |
598 | } |
599 | ||
56b043c8 JL |
600 | /* BB is a block which ends with a COND_EXPR or SWITCH_EXPR and when BB |
601 | is reached via one or more specific incoming edges, we know which | |
602 | outgoing edge from BB will be traversed. | |
603 | ||
1983ac12 | 604 | We want to redirect those incoming edges to the target of the |
56b043c8 JL |
605 | appropriate outgoing edge. Doing so avoids a conditional branch |
606 | and may expose new optimization opportunities. Note that we have | |
607 | to update dominator tree and SSA graph after such changes. | |
608 | ||
6cb38cd4 | 609 | The key to keeping the SSA graph update manageable is to duplicate |
2a7e31df | 610 | the side effects occurring in BB so that those side effects still |
56b043c8 JL |
611 | occur on the paths which bypass BB after redirecting edges. |
612 | ||
613 | We accomplish this by creating duplicates of BB and arranging for | |
614 | the duplicates to unconditionally pass control to one specific | |
615 | successor of BB. We then revector the incoming edges into BB to | |
616 | the appropriate duplicate of BB. | |
617 | ||
b02b9b53 ZD |
618 | If NOLOOP_ONLY is true, we only perform the threading as long as it |
619 | does not affect the structure of the loops in a nontrivial way. */ | |
56b043c8 | 620 | |
d38ffc55 | 621 | static bool |
b02b9b53 | 622 | thread_block (basic_block bb, bool noloop_only) |
56b043c8 JL |
623 | { |
624 | /* E is an incoming edge into BB that we may or may not want to | |
625 | redirect to a duplicate of BB. */ | |
b02b9b53 | 626 | edge e, e2; |
628f6a4e | 627 | edge_iterator ei; |
0823efed | 628 | ssa_local_info_t local_info; |
b02b9b53 | 629 | struct loop *loop = bb->loop_father; |
d38ffc55 | 630 | |
1983ac12 | 631 | /* To avoid scanning a linear array for the element we need we instead |
e7a531ae | 632 | use a hash table. For normal code there should be no noticeable |
1983ac12 JL |
633 | difference. However, if we have a block with a large number of |
634 | incoming and outgoing edges such linear searches can get expensive. */ | |
0823efed | 635 | redirection_data.create (EDGE_COUNT (bb->succs)); |
1983ac12 | 636 | |
b02b9b53 ZD |
637 | /* If we thread the latch of the loop to its exit, the loop ceases to |
638 | exist. Make sure we do not restrict ourselves in order to preserve | |
639 | this loop. */ | |
d51157de | 640 | if (loop->header == bb) |
b02b9b53 ZD |
641 | { |
642 | e = loop_latch_edge (loop); | |
aee2d611 | 643 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
7134c090 | 644 | |
aee2d611 | 645 | if (path) |
b02b9b53 | 646 | { |
aee2d611 JL |
647 | for (unsigned int i = 1; i < path->length (); i++) |
648 | { | |
649 | edge e2 = (*path)[i]->e; | |
650 | ||
651 | if (loop_exit_edge_p (loop, e2)) | |
652 | { | |
653 | loop->header = NULL; | |
654 | loop->latch = NULL; | |
655 | loops_state_set (LOOPS_NEED_FIXUP); | |
656 | } | |
657 | } | |
b02b9b53 ZD |
658 | } |
659 | } | |
d38ffc55 | 660 | |
1983ac12 JL |
661 | /* Record each unique threaded destination into a hash table for |
662 | efficient lookups. */ | |
628f6a4e | 663 | FOR_EACH_EDGE (e, ei, bb->preds) |
56b043c8 | 664 | { |
7134c090 JL |
665 | if (e->aux == NULL) |
666 | continue; | |
667 | ||
aee2d611 JL |
668 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
669 | e2 = path->last ()->e; | |
581aedec JL |
670 | if (!e2 || noloop_only) |
671 | { | |
b02b9b53 | 672 | /* If NOLOOP_ONLY is true, we only allow threading through the |
aee2d611 | 673 | header of a loop to exit edges. |
581aedec JL |
674 | |
675 | There are two cases to consider. The first when BB is the | |
676 | loop header. We will attempt to thread this elsewhere, so | |
677 | we can just continue here. */ | |
678 | ||
679 | if (bb == bb->loop_father->header | |
361b51c0 | 680 | && (!loop_exit_edge_p (bb->loop_father, e2) |
aee2d611 | 681 | || (*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK)) |
581aedec JL |
682 | continue; |
683 | ||
684 | ||
685 | /* The second occurs when there was loop header buried in a jump | |
686 | threading path. We do not try and thread this elsewhere, so | |
687 | just cancel the jump threading request by clearing the AUX | |
688 | field now. */ | |
9e1376e9 JL |
689 | if ((bb->loop_father != e2->src->loop_father |
690 | && !loop_exit_edge_p (e2->src->loop_father, e2)) | |
691 | || (e2->src->loop_father != e2->dest->loop_father | |
692 | && !loop_exit_edge_p (e2->src->loop_father, e2))) | |
581aedec JL |
693 | { |
694 | /* Since this case is not handled by our special code | |
695 | to thread through a loop header, we must explicitly | |
696 | cancel the threading request here. */ | |
aee2d611 JL |
697 | for (unsigned int i = 0; i < path->length (); i++) |
698 | delete (*path)[i]; | |
699 | path->release (); | |
581aedec JL |
700 | e->aux = NULL; |
701 | continue; | |
702 | } | |
703 | } | |
1983ac12 | 704 | |
520af9ec JL |
705 | if (e->dest == e2->src) |
706 | update_bb_profile_for_threading (e->dest, EDGE_FREQUENCY (e), | |
aee2d611 | 707 | e->count, (*THREAD_PATH (e))[1]->e); |
b02b9b53 ZD |
708 | |
709 | /* Insert the outgoing edge into the hash table if it is not | |
710 | already in the hash table. */ | |
361b51c0 | 711 | lookup_redirection_data (e, INSERT); |
56b043c8 JL |
712 | } |
713 | ||
66f97d31 ZD |
714 | /* We do not update dominance info. */ |
715 | free_dominance_info (CDI_DOMINATORS); | |
716 | ||
12df9a2f RG |
717 | /* We know we only thread through the loop header to loop exits. |
718 | Let the basic block duplication hook know we are not creating | |
719 | a multiple entry loop. */ | |
720 | if (noloop_only | |
721 | && bb == bb->loop_father->header) | |
722 | set_loop_copy (bb->loop_father, loop_outer (bb->loop_father)); | |
723 | ||
1983ac12 | 724 | /* Now create duplicates of BB. |
e376fe58 JL |
725 | |
726 | Note that for a block with a high outgoing degree we can waste | |
727 | a lot of time and memory creating and destroying useless edges. | |
728 | ||
729 | So we first duplicate BB and remove the control structure at the | |
730 | tail of the duplicate as well as all outgoing edges from the | |
731 | duplicate. We then use that duplicate block as a template for | |
732 | the rest of the duplicates. */ | |
1983ac12 JL |
733 | local_info.template_block = NULL; |
734 | local_info.bb = bb; | |
d38ffc55 | 735 | local_info.jumps_threaded = false; |
0823efed DN |
736 | redirection_data.traverse <ssa_local_info_t *, ssa_create_duplicates> |
737 | (&local_info); | |
e376fe58 | 738 | |
1983ac12 JL |
739 | /* The template does not have an outgoing edge. Create that outgoing |
740 | edge and update PHI nodes as the edge's target as necessary. | |
e376fe58 | 741 | |
1983ac12 JL |
742 | We do this after creating all the duplicates to avoid creating |
743 | unnecessary edges. */ | |
0823efed DN |
744 | redirection_data.traverse <ssa_local_info_t *, ssa_fixup_template_block> |
745 | (&local_info); | |
e376fe58 | 746 | |
1983ac12 JL |
747 | /* The hash table traversals above created the duplicate blocks (and the |
748 | statements within the duplicate blocks). This loop creates PHI nodes for | |
749 | the duplicated blocks and redirects the incoming edges into BB to reach | |
750 | the duplicates of BB. */ | |
0823efed DN |
751 | redirection_data.traverse <ssa_local_info_t *, ssa_redirect_edges> |
752 | (&local_info); | |
56b043c8 | 753 | |
37840132 | 754 | /* Done with this block. Clear REDIRECTION_DATA. */ |
0823efed | 755 | redirection_data.dispose (); |
d38ffc55 | 756 | |
12df9a2f RG |
757 | if (noloop_only |
758 | && bb == bb->loop_father->header) | |
759 | set_loop_copy (bb->loop_father, NULL); | |
760 | ||
d38ffc55 JL |
761 | /* Indicate to our caller whether or not any jumps were threaded. */ |
762 | return local_info.jumps_threaded; | |
56b043c8 JL |
763 | } |
764 | ||
7134c090 JL |
765 | /* Threads edge E through E->dest to the edge THREAD_TARGET (E). Returns the |
766 | copy of E->dest created during threading, or E->dest if it was not necessary | |
b02b9b53 ZD |
767 | to copy it (E is its single predecessor). */ |
768 | ||
769 | static basic_block | |
770 | thread_single_edge (edge e) | |
771 | { | |
772 | basic_block bb = e->dest; | |
b02b9b53 | 773 | struct redirection_data rd; |
aee2d611 JL |
774 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
775 | edge eto = (*path)[1]->e; | |
b02b9b53 | 776 | |
aee2d611 JL |
777 | for (unsigned int i = 0; i < path->length (); i++) |
778 | delete (*path)[i]; | |
779 | delete path; | |
b02b9b53 ZD |
780 | e->aux = NULL; |
781 | ||
782 | thread_stats.num_threaded_edges++; | |
783 | ||
784 | if (single_pred_p (bb)) | |
785 | { | |
786 | /* If BB has just a single predecessor, we should only remove the | |
787 | control statements at its end, and successors except for ETO. */ | |
788 | remove_ctrl_stmt_and_useless_edges (bb, eto->dest); | |
d9eb5318 RG |
789 | |
790 | /* And fixup the flags on the single remaining edge. */ | |
791 | eto->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE | EDGE_ABNORMAL); | |
792 | eto->flags |= EDGE_FALLTHRU; | |
793 | ||
b02b9b53 ZD |
794 | return bb; |
795 | } | |
796 | ||
797 | /* Otherwise, we need to create a copy. */ | |
520af9ec JL |
798 | if (e->dest == eto->src) |
799 | update_bb_profile_for_threading (bb, EDGE_FREQUENCY (e), e->count, eto); | |
b02b9b53 | 800 | |
1465e5cf JL |
801 | vec<jump_thread_edge *> *npath = new vec<jump_thread_edge *> (); |
802 | jump_thread_edge *x = new jump_thread_edge (e, EDGE_START_JUMP_THREAD); | |
803 | npath->safe_push (x); | |
804 | ||
805 | x = new jump_thread_edge (eto, EDGE_COPY_SRC_BLOCK); | |
806 | npath->safe_push (x); | |
807 | rd.path = npath; | |
b02b9b53 ZD |
808 | |
809 | create_block_for_threading (bb, &rd); | |
a91926b9 | 810 | remove_ctrl_stmt_and_useless_edges (rd.dup_block, NULL); |
520af9ec | 811 | create_edge_and_update_destination_phis (&rd, rd.dup_block); |
b02b9b53 ZD |
812 | |
813 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
814 | fprintf (dump_file, " Threaded jump %d --> %d to %d\n", | |
815 | e->src->index, e->dest->index, rd.dup_block->index); | |
816 | ||
817 | rd.dup_block->count = e->count; | |
818 | rd.dup_block->frequency = EDGE_FREQUENCY (e); | |
819 | single_succ_edge (rd.dup_block)->count = e->count; | |
820 | redirect_edge_and_branch (e, rd.dup_block); | |
821 | flush_pending_stmts (e); | |
822 | ||
823 | return rd.dup_block; | |
824 | } | |
825 | ||
826 | /* Callback for dfs_enumerate_from. Returns true if BB is different | |
827 | from STOP and DBDS_CE_STOP. */ | |
828 | ||
829 | static basic_block dbds_ce_stop; | |
830 | static bool | |
ed7a4b4b | 831 | dbds_continue_enumeration_p (const_basic_block bb, const void *stop) |
b02b9b53 | 832 | { |
ed7a4b4b | 833 | return (bb != (const_basic_block) stop |
b02b9b53 ZD |
834 | && bb != dbds_ce_stop); |
835 | } | |
836 | ||
837 | /* Evaluates the dominance relationship of latch of the LOOP and BB, and | |
838 | returns the state. */ | |
839 | ||
840 | enum bb_dom_status | |
841 | { | |
842 | /* BB does not dominate latch of the LOOP. */ | |
843 | DOMST_NONDOMINATING, | |
844 | /* The LOOP is broken (there is no path from the header to its latch. */ | |
845 | DOMST_LOOP_BROKEN, | |
846 | /* BB dominates the latch of the LOOP. */ | |
847 | DOMST_DOMINATING | |
848 | }; | |
849 | ||
850 | static enum bb_dom_status | |
851 | determine_bb_domination_status (struct loop *loop, basic_block bb) | |
852 | { | |
853 | basic_block *bblocks; | |
854 | unsigned nblocks, i; | |
855 | bool bb_reachable = false; | |
856 | edge_iterator ei; | |
857 | edge e; | |
858 | ||
520af9ec JL |
859 | /* This function assumes BB is a successor of LOOP->header. |
860 | If that is not the case return DOMST_NONDOMINATING which | |
861 | is always safe. */ | |
b02b9b53 ZD |
862 | { |
863 | bool ok = false; | |
864 | ||
865 | FOR_EACH_EDGE (e, ei, bb->preds) | |
866 | { | |
867 | if (e->src == loop->header) | |
868 | { | |
869 | ok = true; | |
870 | break; | |
871 | } | |
872 | } | |
873 | ||
520af9ec JL |
874 | if (!ok) |
875 | return DOMST_NONDOMINATING; | |
b02b9b53 | 876 | } |
b02b9b53 ZD |
877 | |
878 | if (bb == loop->latch) | |
879 | return DOMST_DOMINATING; | |
880 | ||
881 | /* Check that BB dominates LOOP->latch, and that it is back-reachable | |
882 | from it. */ | |
883 | ||
884 | bblocks = XCNEWVEC (basic_block, loop->num_nodes); | |
885 | dbds_ce_stop = loop->header; | |
886 | nblocks = dfs_enumerate_from (loop->latch, 1, dbds_continue_enumeration_p, | |
887 | bblocks, loop->num_nodes, bb); | |
888 | for (i = 0; i < nblocks; i++) | |
889 | FOR_EACH_EDGE (e, ei, bblocks[i]->preds) | |
890 | { | |
891 | if (e->src == loop->header) | |
892 | { | |
893 | free (bblocks); | |
894 | return DOMST_NONDOMINATING; | |
895 | } | |
896 | if (e->src == bb) | |
897 | bb_reachable = true; | |
898 | } | |
899 | ||
900 | free (bblocks); | |
901 | return (bb_reachable ? DOMST_DOMINATING : DOMST_LOOP_BROKEN); | |
902 | } | |
903 | ||
18ce8171 RG |
904 | /* Return true if BB is part of the new pre-header that is created |
905 | when threading the latch to DATA. */ | |
906 | ||
907 | static bool | |
908 | def_split_header_continue_p (const_basic_block bb, const void *data) | |
909 | { | |
910 | const_basic_block new_header = (const_basic_block) data; | |
535269f4 JH |
911 | const struct loop *l; |
912 | ||
913 | if (bb == new_header | |
914 | || loop_depth (bb->loop_father) < loop_depth (new_header->loop_father)) | |
915 | return false; | |
916 | for (l = bb->loop_father; l; l = loop_outer (l)) | |
917 | if (l == new_header->loop_father) | |
918 | return true; | |
919 | return false; | |
18ce8171 RG |
920 | } |
921 | ||
b02b9b53 ZD |
922 | /* Thread jumps through the header of LOOP. Returns true if cfg changes. |
923 | If MAY_PEEL_LOOP_HEADERS is false, we avoid threading from entry edges | |
924 | to the inside of the loop. */ | |
925 | ||
926 | static bool | |
927 | thread_through_loop_header (struct loop *loop, bool may_peel_loop_headers) | |
928 | { | |
929 | basic_block header = loop->header; | |
930 | edge e, tgt_edge, latch = loop_latch_edge (loop); | |
931 | edge_iterator ei; | |
932 | basic_block tgt_bb, atgt_bb; | |
933 | enum bb_dom_status domst; | |
934 | ||
935 | /* We have already threaded through headers to exits, so all the threading | |
936 | requests now are to the inside of the loop. We need to avoid creating | |
937 | irreducible regions (i.e., loops with more than one entry block), and | |
938 | also loop with several latch edges, or new subloops of the loop (although | |
939 | there are cases where it might be appropriate, it is difficult to decide, | |
940 | and doing it wrongly may confuse other optimizers). | |
941 | ||
942 | We could handle more general cases here. However, the intention is to | |
943 | preserve some information about the loop, which is impossible if its | |
944 | structure changes significantly, in a way that is not well understood. | |
945 | Thus we only handle few important special cases, in which also updating | |
946 | of the loop-carried information should be feasible: | |
947 | ||
948 | 1) Propagation of latch edge to a block that dominates the latch block | |
949 | of a loop. This aims to handle the following idiom: | |
950 | ||
951 | first = 1; | |
952 | while (1) | |
953 | { | |
954 | if (first) | |
955 | initialize; | |
956 | first = 0; | |
957 | body; | |
958 | } | |
959 | ||
960 | After threading the latch edge, this becomes | |
961 | ||
962 | first = 1; | |
963 | if (first) | |
964 | initialize; | |
965 | while (1) | |
966 | { | |
967 | first = 0; | |
968 | body; | |
969 | } | |
970 | ||
971 | The original header of the loop is moved out of it, and we may thread | |
972 | the remaining edges through it without further constraints. | |
973 | ||
974 | 2) All entry edges are propagated to a single basic block that dominates | |
975 | the latch block of the loop. This aims to handle the following idiom | |
976 | (normally created for "for" loops): | |
977 | ||
978 | i = 0; | |
979 | while (1) | |
980 | { | |
981 | if (i >= 100) | |
982 | break; | |
983 | body; | |
984 | i++; | |
985 | } | |
986 | ||
987 | This becomes | |
988 | ||
989 | i = 0; | |
990 | while (1) | |
991 | { | |
992 | body; | |
993 | i++; | |
994 | if (i >= 100) | |
995 | break; | |
996 | } | |
997 | */ | |
998 | ||
999 | /* Threading through the header won't improve the code if the header has just | |
1000 | one successor. */ | |
1001 | if (single_succ_p (header)) | |
1002 | goto fail; | |
1003 | ||
1004 | if (latch->aux) | |
1005 | { | |
aee2d611 JL |
1006 | vec<jump_thread_edge *> *path = THREAD_PATH (latch); |
1007 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
361b51c0 | 1008 | goto fail; |
aee2d611 | 1009 | tgt_edge = (*path)[1]->e; |
b02b9b53 ZD |
1010 | tgt_bb = tgt_edge->dest; |
1011 | } | |
1012 | else if (!may_peel_loop_headers | |
1013 | && !redirection_block_p (loop->header)) | |
1014 | goto fail; | |
1015 | else | |
1016 | { | |
1017 | tgt_bb = NULL; | |
1018 | tgt_edge = NULL; | |
1019 | FOR_EACH_EDGE (e, ei, header->preds) | |
1020 | { | |
1021 | if (!e->aux) | |
1022 | { | |
1023 | if (e == latch) | |
1024 | continue; | |
1025 | ||
1026 | /* If latch is not threaded, and there is a header | |
1027 | edge that is not threaded, we would create loop | |
1028 | with multiple entries. */ | |
1029 | goto fail; | |
1030 | } | |
1031 | ||
aee2d611 JL |
1032 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1033 | ||
1034 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
361b51c0 | 1035 | goto fail; |
aee2d611 | 1036 | tgt_edge = (*path)[1]->e; |
b02b9b53 ZD |
1037 | atgt_bb = tgt_edge->dest; |
1038 | if (!tgt_bb) | |
1039 | tgt_bb = atgt_bb; | |
1040 | /* Two targets of threading would make us create loop | |
1041 | with multiple entries. */ | |
1042 | else if (tgt_bb != atgt_bb) | |
1043 | goto fail; | |
1044 | } | |
1045 | ||
1046 | if (!tgt_bb) | |
1047 | { | |
1048 | /* There are no threading requests. */ | |
1049 | return false; | |
1050 | } | |
1051 | ||
1052 | /* Redirecting to empty loop latch is useless. */ | |
1053 | if (tgt_bb == loop->latch | |
1054 | && empty_block_p (loop->latch)) | |
1055 | goto fail; | |
1056 | } | |
1057 | ||
1058 | /* The target block must dominate the loop latch, otherwise we would be | |
1059 | creating a subloop. */ | |
1060 | domst = determine_bb_domination_status (loop, tgt_bb); | |
1061 | if (domst == DOMST_NONDOMINATING) | |
1062 | goto fail; | |
1063 | if (domst == DOMST_LOOP_BROKEN) | |
1064 | { | |
1065 | /* If the loop ceased to exist, mark it as such, and thread through its | |
1066 | original header. */ | |
1067 | loop->header = NULL; | |
1068 | loop->latch = NULL; | |
7d776ee2 | 1069 | loops_state_set (LOOPS_NEED_FIXUP); |
b02b9b53 ZD |
1070 | return thread_block (header, false); |
1071 | } | |
1072 | ||
1073 | if (tgt_bb->loop_father->header == tgt_bb) | |
1074 | { | |
1075 | /* If the target of the threading is a header of a subloop, we need | |
1076 | to create a preheader for it, so that the headers of the two loops | |
1077 | do not merge. */ | |
1078 | if (EDGE_COUNT (tgt_bb->preds) > 2) | |
1079 | { | |
1080 | tgt_bb = create_preheader (tgt_bb->loop_father, 0); | |
1081 | gcc_assert (tgt_bb != NULL); | |
1082 | } | |
1083 | else | |
1084 | tgt_bb = split_edge (tgt_edge); | |
1085 | } | |
b8698a0f | 1086 | |
b02b9b53 ZD |
1087 | if (latch->aux) |
1088 | { | |
18ce8171 RG |
1089 | basic_block *bblocks; |
1090 | unsigned nblocks, i; | |
1091 | ||
07b1bf20 RG |
1092 | /* First handle the case latch edge is redirected. We are copying |
1093 | the loop header but not creating a multiple entry loop. Make the | |
1094 | cfg manipulation code aware of that fact. */ | |
1095 | set_loop_copy (loop, loop); | |
b02b9b53 | 1096 | loop->latch = thread_single_edge (latch); |
07b1bf20 | 1097 | set_loop_copy (loop, NULL); |
b02b9b53 ZD |
1098 | gcc_assert (single_succ (loop->latch) == tgt_bb); |
1099 | loop->header = tgt_bb; | |
1100 | ||
18ce8171 RG |
1101 | /* Remove the new pre-header blocks from our loop. */ |
1102 | bblocks = XCNEWVEC (basic_block, loop->num_nodes); | |
1103 | nblocks = dfs_enumerate_from (header, 0, def_split_header_continue_p, | |
1104 | bblocks, loop->num_nodes, tgt_bb); | |
1105 | for (i = 0; i < nblocks; i++) | |
1779dc34 RG |
1106 | if (bblocks[i]->loop_father == loop) |
1107 | { | |
1108 | remove_bb_from_loops (bblocks[i]); | |
1109 | add_bb_to_loop (bblocks[i], loop_outer (loop)); | |
1110 | } | |
18ce8171 RG |
1111 | free (bblocks); |
1112 | ||
a8886f7d RG |
1113 | /* If the new header has multiple latches mark it so. */ |
1114 | FOR_EACH_EDGE (e, ei, loop->header->preds) | |
1115 | if (e->src->loop_father == loop | |
1116 | && e->src != loop->latch) | |
1117 | { | |
1118 | loop->latch = NULL; | |
1119 | loops_state_set (LOOPS_MAY_HAVE_MULTIPLE_LATCHES); | |
1120 | } | |
1121 | ||
18ce8171 RG |
1122 | /* Cancel remaining threading requests that would make the |
1123 | loop a multiple entry loop. */ | |
1124 | FOR_EACH_EDGE (e, ei, header->preds) | |
1125 | { | |
1126 | edge e2; | |
a8886f7d | 1127 | |
18ce8171 RG |
1128 | if (e->aux == NULL) |
1129 | continue; | |
1130 | ||
aee2d611 JL |
1131 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1132 | e2 = path->last ()->e; | |
18ce8171 RG |
1133 | |
1134 | if (e->src->loop_father != e2->dest->loop_father | |
1135 | && e2->dest != loop->header) | |
1136 | { | |
aee2d611 JL |
1137 | for (unsigned int i = 0; i < path->length (); i++) |
1138 | delete (*path)[i]; | |
1139 | path->release (); | |
18ce8171 RG |
1140 | e->aux = NULL; |
1141 | } | |
1142 | } | |
1143 | ||
b02b9b53 ZD |
1144 | /* Thread the remaining edges through the former header. */ |
1145 | thread_block (header, false); | |
1146 | } | |
1147 | else | |
1148 | { | |
1149 | basic_block new_preheader; | |
1150 | ||
1151 | /* Now consider the case entry edges are redirected to the new entry | |
1152 | block. Remember one entry edge, so that we can find the new | |
7134c090 | 1153 | preheader (its destination after threading). */ |
b02b9b53 ZD |
1154 | FOR_EACH_EDGE (e, ei, header->preds) |
1155 | { | |
1156 | if (e->aux) | |
1157 | break; | |
1158 | } | |
1159 | ||
1160 | /* The duplicate of the header is the new preheader of the loop. Ensure | |
1161 | that it is placed correctly in the loop hierarchy. */ | |
561e8a90 | 1162 | set_loop_copy (loop, loop_outer (loop)); |
b02b9b53 ZD |
1163 | |
1164 | thread_block (header, false); | |
561e8a90 | 1165 | set_loop_copy (loop, NULL); |
b02b9b53 ZD |
1166 | new_preheader = e->dest; |
1167 | ||
1168 | /* Create the new latch block. This is always necessary, as the latch | |
1169 | must have only a single successor, but the original header had at | |
1170 | least two successors. */ | |
1171 | loop->latch = NULL; | |
1172 | mfb_kj_edge = single_succ_edge (new_preheader); | |
1173 | loop->header = mfb_kj_edge->dest; | |
1174 | latch = make_forwarder_block (tgt_bb, mfb_keep_just, NULL); | |
1175 | loop->header = latch->dest; | |
1176 | loop->latch = latch->src; | |
1177 | } | |
b8698a0f | 1178 | |
b02b9b53 ZD |
1179 | return true; |
1180 | ||
1181 | fail: | |
1182 | /* We failed to thread anything. Cancel the requests. */ | |
1183 | FOR_EACH_EDGE (e, ei, header->preds) | |
1184 | { | |
aee2d611 JL |
1185 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1186 | ||
1187 | if (path) | |
1188 | { | |
1189 | for (unsigned int i = 0; i < path->length (); i++) | |
1190 | delete (*path)[i]; | |
1191 | path->release (); | |
1192 | e->aux = NULL; | |
1193 | } | |
b02b9b53 ZD |
1194 | } |
1195 | return false; | |
1196 | } | |
1197 | ||
8d34e421 JL |
1198 | /* E1 and E2 are edges into the same basic block. Return TRUE if the |
1199 | PHI arguments associated with those edges are equal or there are no | |
1200 | PHI arguments, otherwise return FALSE. */ | |
1201 | ||
1202 | static bool | |
1203 | phi_args_equal_on_edges (edge e1, edge e2) | |
1204 | { | |
1205 | gimple_stmt_iterator gsi; | |
1206 | int indx1 = e1->dest_idx; | |
1207 | int indx2 = e2->dest_idx; | |
1208 | ||
1209 | for (gsi = gsi_start_phis (e1->dest); !gsi_end_p (gsi); gsi_next (&gsi)) | |
1210 | { | |
1211 | gimple phi = gsi_stmt (gsi); | |
1212 | ||
1213 | if (!operand_equal_p (gimple_phi_arg_def (phi, indx1), | |
1214 | gimple_phi_arg_def (phi, indx2), 0)) | |
1215 | return false; | |
1216 | } | |
1217 | return true; | |
1218 | } | |
1219 | ||
8702a557 | 1220 | /* Walk through the registered jump threads and convert them into a |
c0220ea4 | 1221 | form convenient for this pass. |
8702a557 JL |
1222 | |
1223 | Any block which has incoming edges threaded to outgoing edges | |
1224 | will have its entry in THREADED_BLOCK set. | |
56b043c8 | 1225 | |
8702a557 JL |
1226 | Any threaded edge will have its new outgoing edge stored in the |
1227 | original edge's AUX field. | |
56b043c8 | 1228 | |
8702a557 JL |
1229 | This form avoids the need to walk all the edges in the CFG to |
1230 | discover blocks which need processing and avoids unnecessary | |
1231 | hash table lookups to map from threaded edge to new target. */ | |
56b043c8 | 1232 | |
8702a557 JL |
1233 | static void |
1234 | mark_threaded_blocks (bitmap threaded_blocks) | |
1235 | { | |
1236 | unsigned int i; | |
b02b9b53 ZD |
1237 | bitmap_iterator bi; |
1238 | bitmap tmp = BITMAP_ALLOC (NULL); | |
1239 | basic_block bb; | |
1240 | edge e; | |
1241 | edge_iterator ei; | |
8702a557 | 1242 | |
34554d1a JL |
1243 | /* It is possible to have jump threads in which one is a subpath |
1244 | of the other. ie, (A, B), (B, C), (C, D) where B is a joiner | |
1245 | block and (B, C), (C, D) where no joiner block exists. | |
1246 | ||
1247 | When this occurs ignore the jump thread request with the joiner | |
1248 | block. It's totally subsumed by the simpler jump thread request. | |
1249 | ||
b5c4ff78 | 1250 | This results in less block copying, simpler CFGs. More importantly, |
34554d1a JL |
1251 | when we duplicate the joiner block, B, in this case we will create |
1252 | a new threading opportunity that we wouldn't be able to optimize | |
aee2d611 | 1253 | until the next jump threading iteration. |
34554d1a JL |
1254 | |
1255 | So first convert the jump thread requests which do not require a | |
1256 | joiner block. */ | |
aee2d611 | 1257 | for (i = 0; i < paths.length (); i++) |
8702a557 | 1258 | { |
aee2d611 | 1259 | vec<jump_thread_edge *> *path = paths[i]; |
8702a557 | 1260 | |
aee2d611 | 1261 | if ((*path)[1]->type != EDGE_COPY_SRC_JOINER_BLOCK) |
34554d1a | 1262 | { |
aee2d611 JL |
1263 | edge e = (*path)[0]->e; |
1264 | e->aux = (void *)path; | |
34554d1a JL |
1265 | bitmap_set_bit (tmp, e->dest->index); |
1266 | } | |
b02b9b53 ZD |
1267 | } |
1268 | ||
b5c4ff78 JL |
1269 | /* Now iterate again, converting cases where we want to thread |
1270 | through a joiner block, but only if no other edge on the path | |
1271 | already has a jump thread attached to it. */ | |
aee2d611 | 1272 | for (i = 0; i < paths.length (); i++) |
34554d1a | 1273 | { |
aee2d611 | 1274 | vec<jump_thread_edge *> *path = paths[i]; |
34554d1a | 1275 | |
b5c4ff78 JL |
1276 | |
1277 | if ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
34554d1a | 1278 | { |
b5c4ff78 JL |
1279 | unsigned int j; |
1280 | ||
1281 | for (j = 0; j < path->length (); j++) | |
1282 | if ((*path)[j]->e->aux != NULL) | |
1283 | break; | |
1284 | ||
1285 | /* If we iterated through the entire path without exiting the loop, | |
1286 | then we are good to go, attach the path to the starting edge. */ | |
1287 | if (j == path->length ()) | |
1288 | { | |
1289 | edge e = (*path)[0]->e; | |
1290 | e->aux = path; | |
1291 | bitmap_set_bit (tmp, e->dest->index); | |
1292 | } | |
34554d1a JL |
1293 | } |
1294 | } | |
1295 | ||
8d34e421 JL |
1296 | /* If we have a joiner block (J) which has two successors S1 and S2 and |
1297 | we are threading though S1 and the final destination of the thread | |
1298 | is S2, then we must verify that any PHI nodes in S2 have the same | |
1299 | PHI arguments for the edge J->S2 and J->S1->...->S2. | |
1300 | ||
1301 | We used to detect this prior to registering the jump thread, but | |
1302 | that prohibits propagation of edge equivalences into non-dominated | |
aee2d611 | 1303 | PHI nodes as the equivalency test might occur before propagation. |
8d34e421 JL |
1304 | |
1305 | This works for now, but will need improvement as part of the FSA | |
aee2d611 | 1306 | optimization. |
8d34e421 JL |
1307 | |
1308 | Note since we've moved the thread request data to the edges, | |
1309 | we have to iterate on those rather than the threaded_edges vector. */ | |
1310 | EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
1311 | { | |
1312 | bb = BASIC_BLOCK (i); | |
1313 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1314 | { | |
1315 | if (e->aux) | |
1316 | { | |
aee2d611 JL |
1317 | vec<jump_thread_edge *> *path = THREAD_PATH (e); |
1318 | bool have_joiner = ((*path)[1]->type == EDGE_COPY_SRC_JOINER_BLOCK); | |
8d34e421 JL |
1319 | |
1320 | if (have_joiner) | |
1321 | { | |
1322 | basic_block joiner = e->dest; | |
aee2d611 | 1323 | edge final_edge = path->last ()->e; |
8d34e421 JL |
1324 | basic_block final_dest = final_edge->dest; |
1325 | edge e2 = find_edge (joiner, final_dest); | |
1326 | ||
1327 | if (e2 && !phi_args_equal_on_edges (e2, final_edge)) | |
1328 | { | |
aee2d611 JL |
1329 | for (unsigned int i = 0; i < path->length (); i++) |
1330 | delete (*path)[i]; | |
1331 | path->release (); | |
8d34e421 JL |
1332 | e->aux = NULL; |
1333 | } | |
1334 | } | |
1335 | } | |
1336 | } | |
1337 | } | |
1338 | ||
34554d1a | 1339 | |
b02b9b53 ZD |
1340 | /* If optimizing for size, only thread through block if we don't have |
1341 | to duplicate it or it's an otherwise empty redirection block. */ | |
efd8f750 | 1342 | if (optimize_function_for_size_p (cfun)) |
b02b9b53 ZD |
1343 | { |
1344 | EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
1345 | { | |
1346 | bb = BASIC_BLOCK (i); | |
1347 | if (EDGE_COUNT (bb->preds) > 1 | |
1348 | && !redirection_block_p (bb)) | |
1349 | { | |
1350 | FOR_EACH_EDGE (e, ei, bb->preds) | |
7134c090 | 1351 | { |
aee2d611 JL |
1352 | if (e->aux) |
1353 | { | |
1354 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
1355 | for (unsigned int i = 0; i < path->length (); i++) | |
1356 | delete (*path)[i]; | |
1357 | path->release (); | |
1358 | e->aux = NULL; | |
1359 | } | |
7134c090 | 1360 | } |
b02b9b53 ZD |
1361 | } |
1362 | else | |
1363 | bitmap_set_bit (threaded_blocks, i); | |
1364 | } | |
8702a557 | 1365 | } |
b02b9b53 ZD |
1366 | else |
1367 | bitmap_copy (threaded_blocks, tmp); | |
1368 | ||
ef3cfba2 JL |
1369 | /* Look for jump threading paths which cross multiple loop headers. |
1370 | ||
1371 | The code to thread through loop headers will change the CFG in ways | |
1372 | that break assumptions made by the loop optimization code. | |
1373 | ||
1374 | We don't want to blindly cancel the requests. We can instead do better | |
1375 | by trimming off the end of the jump thread path. */ | |
1376 | EXECUTE_IF_SET_IN_BITMAP (tmp, 0, i, bi) | |
1377 | { | |
1378 | basic_block bb = BASIC_BLOCK (i); | |
1379 | FOR_EACH_EDGE (e, ei, bb->preds) | |
1380 | { | |
1381 | if (e->aux) | |
1382 | { | |
1383 | vec<jump_thread_edge *> *path = THREAD_PATH (e); | |
1384 | ||
1385 | /* Basically we're looking for a situation where we can see | |
1386 | 3 or more loop structures on a jump threading path. */ | |
1387 | ||
1388 | struct loop *first_father = (*path)[0]->e->src->loop_father; | |
1389 | struct loop *second_father = NULL; | |
1390 | for (unsigned int i = 0; i < path->length (); i++) | |
1391 | { | |
1392 | /* See if this is a loop father we have not seen before. */ | |
1393 | if ((*path)[i]->e->dest->loop_father != first_father | |
1394 | && (*path)[i]->e->dest->loop_father != second_father) | |
1395 | { | |
1396 | /* We've already seen two loop fathers, so we | |
1397 | need to trim this jump threading path. */ | |
1398 | if (second_father != NULL) | |
1399 | { | |
1400 | /* Trim from entry I onwards. */ | |
1401 | for (unsigned int j = i; j < path->length (); j++) | |
1402 | delete (*path)[j]; | |
1403 | path->truncate (i); | |
1404 | ||
1405 | /* Now that we've truncated the path, make sure | |
1406 | what's left is still valid. We need at least | |
1407 | two edges on the path and the last edge can not | |
1408 | be a joiner. This should never happen, but let's | |
1409 | be safe. */ | |
1410 | if (path->length () < 2 | |
1411 | || (path->last ()->type | |
1412 | == EDGE_COPY_SRC_JOINER_BLOCK)) | |
1413 | { | |
1414 | for (unsigned int i = 0; i < path->length (); i++) | |
1415 | delete (*path)[i]; | |
1416 | path->release (); | |
1417 | e->aux = NULL; | |
1418 | } | |
1419 | break; | |
1420 | } | |
1421 | else | |
1422 | { | |
1423 | second_father = (*path)[i]->e->dest->loop_father; | |
1424 | } | |
1425 | } | |
1426 | } | |
1427 | } | |
1428 | } | |
1429 | } | |
1430 | ||
c3284718 | 1431 | BITMAP_FREE (tmp); |
8702a557 JL |
1432 | } |
1433 | ||
1434 | ||
1435 | /* Walk through all blocks and thread incoming edges to the appropriate | |
1436 | outgoing edge for each edge pair recorded in THREADED_EDGES. | |
56b043c8 JL |
1437 | |
1438 | It is the caller's responsibility to fix the dominance information | |
1439 | and rewrite duplicated SSA_NAMEs back into SSA form. | |
1440 | ||
b02b9b53 ZD |
1441 | If MAY_PEEL_LOOP_HEADERS is false, we avoid threading edges through |
1442 | loop headers if it does not simplify the loop. | |
1443 | ||
471854f8 | 1444 | Returns true if one or more edges were threaded, false otherwise. */ |
56b043c8 JL |
1445 | |
1446 | bool | |
b02b9b53 | 1447 | thread_through_all_blocks (bool may_peel_loop_headers) |
56b043c8 | 1448 | { |
56b043c8 | 1449 | bool retval = false; |
4aab792d KH |
1450 | unsigned int i; |
1451 | bitmap_iterator bi; | |
8702a557 | 1452 | bitmap threaded_blocks; |
b02b9b53 ZD |
1453 | struct loop *loop; |
1454 | loop_iterator li; | |
8702a557 | 1455 | |
d51157de ZD |
1456 | /* We must know about loops in order to preserve them. */ |
1457 | gcc_assert (current_loops != NULL); | |
1458 | ||
aee2d611 | 1459 | if (!paths.exists ()) |
8702a557 | 1460 | return false; |
56b043c8 | 1461 | |
8702a557 | 1462 | threaded_blocks = BITMAP_ALLOC (NULL); |
a4233c29 | 1463 | memset (&thread_stats, 0, sizeof (thread_stats)); |
d38ffc55 | 1464 | |
8702a557 JL |
1465 | mark_threaded_blocks (threaded_blocks); |
1466 | ||
561e8a90 | 1467 | initialize_original_copy_tables (); |
b02b9b53 ZD |
1468 | |
1469 | /* First perform the threading requests that do not affect | |
1470 | loop structure. */ | |
4aab792d | 1471 | EXECUTE_IF_SET_IN_BITMAP (threaded_blocks, 0, i, bi) |
56b043c8 | 1472 | { |
4aab792d KH |
1473 | basic_block bb = BASIC_BLOCK (i); |
1474 | ||
1475 | if (EDGE_COUNT (bb->preds) > 0) | |
b02b9b53 ZD |
1476 | retval |= thread_block (bb, true); |
1477 | } | |
1478 | ||
1479 | /* Then perform the threading through loop headers. We start with the | |
1480 | innermost loop, so that the changes in cfg we perform won't affect | |
1481 | further threading. */ | |
d51157de | 1482 | FOR_EACH_LOOP (li, loop, LI_FROM_INNERMOST) |
b02b9b53 | 1483 | { |
d51157de ZD |
1484 | if (!loop->header |
1485 | || !bitmap_bit_p (threaded_blocks, loop->header->index)) | |
1486 | continue; | |
b02b9b53 | 1487 | |
d51157de | 1488 | retval |= thread_through_loop_header (loop, may_peel_loop_headers); |
56b043c8 | 1489 | } |
d38ffc55 | 1490 | |
01902653 RG |
1491 | statistics_counter_event (cfun, "Jumps threaded", |
1492 | thread_stats.num_threaded_edges); | |
a4233c29 | 1493 | |
561e8a90 ZD |
1494 | free_original_copy_tables (); |
1495 | ||
8702a557 JL |
1496 | BITMAP_FREE (threaded_blocks); |
1497 | threaded_blocks = NULL; | |
aee2d611 | 1498 | paths.release (); |
b02b9b53 | 1499 | |
592c303d | 1500 | if (retval) |
f87000d0 | 1501 | loops_state_set (LOOPS_NEED_FIXUP); |
592c303d | 1502 | |
56b043c8 JL |
1503 | return retval; |
1504 | } | |
8702a557 | 1505 | |
5254eac4 JL |
1506 | /* Dump a jump threading path, including annotations about each |
1507 | edge in the path. */ | |
1508 | ||
1509 | static void | |
1510 | dump_jump_thread_path (FILE *dump_file, vec<jump_thread_edge *> path) | |
1511 | { | |
1512 | fprintf (dump_file, | |
1513 | " Registering jump thread: (%d, %d) incoming edge; ", | |
1514 | path[0]->e->src->index, path[0]->e->dest->index); | |
1515 | ||
1516 | for (unsigned int i = 1; i < path.length (); i++) | |
1517 | { | |
1518 | /* We can get paths with a NULL edge when the final destination | |
1519 | of a jump thread turns out to be a constant address. We dump | |
1520 | those paths when debugging, so we have to be prepared for that | |
1521 | possibility here. */ | |
1522 | if (path[i]->e == NULL) | |
1523 | continue; | |
1524 | ||
1525 | if (path[i]->type == EDGE_COPY_SRC_JOINER_BLOCK) | |
1526 | fprintf (dump_file, " (%d, %d) joiner; ", | |
1527 | path[i]->e->src->index, path[i]->e->dest->index); | |
1528 | if (path[i]->type == EDGE_COPY_SRC_BLOCK) | |
1529 | fprintf (dump_file, " (%d, %d) normal;", | |
1530 | path[i]->e->src->index, path[i]->e->dest->index); | |
1531 | if (path[i]->type == EDGE_NO_COPY_SRC_BLOCK) | |
1532 | fprintf (dump_file, " (%d, %d) nocopy;", | |
1533 | path[i]->e->src->index, path[i]->e->dest->index); | |
1534 | } | |
1535 | fputc ('\n', dump_file); | |
1536 | } | |
1537 | ||
8702a557 JL |
1538 | /* Register a jump threading opportunity. We queue up all the jump |
1539 | threading opportunities discovered by a pass and update the CFG | |
1540 | and SSA form all at once. | |
1541 | ||
fa10beec | 1542 | E is the edge we can thread, E2 is the new target edge, i.e., we |
8702a557 JL |
1543 | are effectively recording that E->dest can be changed to E2->dest |
1544 | after fixing the SSA graph. */ | |
1545 | ||
1546 | void | |
aee2d611 | 1547 | register_jump_thread (vec<jump_thread_edge *> *path) |
8702a557 | 1548 | { |
01e127b1 JL |
1549 | if (!dbg_cnt (registered_jump_thread)) |
1550 | { | |
1551 | for (unsigned int i = 0; i < path->length (); i++) | |
1552 | delete (*path)[i]; | |
1553 | path->release (); | |
1554 | return; | |
1555 | } | |
1556 | ||
5254eac4 JL |
1557 | /* First make sure there are no NULL outgoing edges on the jump threading |
1558 | path. That can happen for jumping to a constant address. */ | |
aee2d611 JL |
1559 | for (unsigned int i = 0; i < path->length (); i++) |
1560 | if ((*path)[i]->e == NULL) | |
5254eac4 JL |
1561 | { |
1562 | if (dump_file && (dump_flags & TDF_DETAILS)) | |
1563 | { | |
1564 | fprintf (dump_file, | |
1565 | "Found NULL edge in jump threading path. Cancelling jump thread:\n"); | |
aee2d611 | 1566 | dump_jump_thread_path (dump_file, *path); |
5254eac4 | 1567 | } |
aee2d611 JL |
1568 | |
1569 | for (unsigned int i = 0; i < path->length (); i++) | |
1570 | delete (*path)[i]; | |
1571 | path->release (); | |
5254eac4 JL |
1572 | return; |
1573 | } | |
b9ebee5d | 1574 | |
3b18bc42 | 1575 | if (dump_file && (dump_flags & TDF_DETAILS)) |
aee2d611 | 1576 | dump_jump_thread_path (dump_file, *path); |
3b18bc42 | 1577 | |
aee2d611 JL |
1578 | if (!paths.exists ()) |
1579 | paths.create (5); | |
3b18bc42 | 1580 | |
aee2d611 | 1581 | paths.safe_push (path); |
8702a557 | 1582 | } |