Line data Source code
1 : /* Strongly-connected copy propagation pass for the GNU compiler.
2 : Copyright (C) 2023-2026 Free Software Foundation, Inc.
3 : Contributed by Filip Kastl <fkastl@suse.cz>
4 :
5 : This file is part of GCC.
6 :
7 : GCC is free software; you can redistribute it and/or modify it under
8 : the terms of the GNU General Public License as published by the Free
9 : Software Foundation; either version 3, or (at your option) any later
10 : version.
11 :
12 : GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 : WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 : FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
15 : for more details.
16 :
17 : You should have received a copy of the GNU General Public License
18 : along with GCC; see the file COPYING3. If not see
19 : <http://www.gnu.org/licenses/>. */
20 :
21 : #define INCLUDE_ALGORITHM
22 : #include "config.h"
23 : #include "system.h"
24 : #include "coretypes.h"
25 : #include "backend.h"
26 : #include "tree.h"
27 : #include "gimple.h"
28 : #include "tree-pass.h"
29 : #include "ssa.h"
30 : #include "gimple-iterator.h"
31 : #include "vec.h"
32 : #include "hash-set.h"
33 : #include "ssa-iterators.h"
34 : #include "gimple-fold.h"
35 : #include "gimplify.h"
36 : #include "tree-cfg.h"
37 : #include "tree-eh.h"
38 : #include "builtins.h"
39 : #include "tree-ssa-dce.h"
40 : #include "fold-const.h"
41 : #include "tree-pretty-print.h"
42 :
43 : /* Strongly connected copy propagation pass.
44 :
45 : This is a lightweight copy propagation pass that is also able to eliminate
46 : redundant PHI statements. The pass considers the following types of copy
47 : statements:
48 :
49 : 1 An assignment statement with a single argument.
50 :
51 : _3 = _2;
52 : _4 = 5;
53 :
54 : 2 A degenerate PHI statement. A degenerate PHI is a PHI that only refers to
55 : itself or one other value.
56 :
57 : _5 = PHI <_1>;
58 : _6 = PHI <_6, _6, _1, _1>;
59 : _7 = PHI <16, _7>;
60 :
61 : 3 A set of PHI statements that only refer to each other or to one other
62 : value.
63 :
64 : _8 = PHI <_9, _10>;
65 : _9 = PHI <_8, _10>;
66 : _10 = PHI <_8, _9, _1>;
67 :
68 : All of these statements produce copies and can be eliminated from the
69 : program. For a copy statement we identify the value it creates a copy of
70 : and replace references to the statement with the value -- we propagate the
71 : copy.
72 :
73 : _3 = _2; // Replace all occurences of _3 by _2
74 :
75 : _8 = PHI <_9, _10>;
76 : _9 = PHI <_8, _10>;
77 : _10 = PHI <_8, _9, _1>; // Replace all occurences of _8, _9 and _10 by _1
78 :
79 : To find all three types of copy statements we use an algorithm based on
80 : strongly-connected components (SCCs) in dataflow graph. The algorithm was
81 : introduced in an article from 2013[1]. We describe the algorithm below.
82 :
83 : To identify SCCs we implement the Robert Tarjan's SCC algorithm. For the
84 : SCC computation we wrap potential copy statements in the 'vertex' struct.
85 : To each of these statements we also assign a vertex number ('vxnum'). Since
86 : the main algorithm has to be able to compute SCCs of subgraphs of the whole
87 : dataflow graph we use GIMPLE stmt flags to prevent Tarjan's algorithm from
88 : leaving the subgraph.
89 :
90 : References:
91 :
92 : [1] Simple and Efficient Construction of Static Single Assignmemnt Form,
93 : Braun, Buchwald, Hack, Leissa, Mallon, Zwinkau, 2013, LNCS vol. 7791,
94 : Section 3.2. */
95 :
96 : namespace {
97 :
98 : /* State of vertex during SCC discovery.
99 :
100 : unvisited Vertex hasn't yet been popped from worklist.
101 : vopen DFS has visited vertex for the first time. Vertex has been put
102 : on Tarjan stack.
103 : closed DFS has backtracked through vertex. At this point, vertex
104 : doesn't have any unvisited neighbors.
105 : in_scc Vertex has been popped from Tarjan stack. */
106 :
107 : enum vstate
108 : {
109 : unvisited,
110 : vopen,
111 : closed,
112 : in_scc
113 : };
114 :
115 : /* Information about a vertex. Used by SCC discovery. */
116 :
117 : struct vertex
118 : {
119 : bool active; /* scc_discovery::compute_sccs () only considers a subgraph of
120 : the whole dataflow graph. It uses this flag so that it knows
121 : which vertices are part of this subgraph. */
122 : vstate state;
123 : unsigned index;
124 : unsigned lowlink;
125 : };
126 :
127 : /* SCC discovery.
128 :
129 : Used to find SCCs in a dataflow graph. Implements Tarjan's SCC
130 : algorithm. */
131 :
132 : class scc_discovery
133 : {
134 : public:
135 : scc_discovery ();
136 : ~scc_discovery ();
137 : auto_vec<vec<gimple *>> compute_sccs (vec<gimple *> &stmts);
138 :
139 : private:
140 : vertex* vertices; /* Indexed by SSA_NAME_VERSION. */
141 : auto_vec<unsigned> worklist; /* DFS stack. */
142 : auto_vec<unsigned> stack; /* Tarjan stack. */
143 :
144 : void visit_neighbor (tree neigh_tree, unsigned parent_vxnum);
145 : };
146 :
147 3453819 : scc_discovery::scc_discovery ()
148 : {
149 : /* Create vertex struct for each SSA name. */
150 6907638 : vertices = XNEWVEC (struct vertex, num_ssa_names);
151 3453819 : unsigned i = 0;
152 130153589 : for (i = 0; i < num_ssa_names; i++)
153 126699770 : vertices[i].active = false;
154 3453819 : }
155 :
156 3453819 : scc_discovery::~scc_discovery ()
157 : {
158 3453819 : XDELETEVEC (vertices);
159 3453819 : }
160 :
161 : /* Part of 'scc_discovery::compute_sccs ()'. */
162 :
163 : void
164 45892352 : scc_discovery::visit_neighbor (tree neigh_tree, unsigned parent_version)
165 : {
166 45892352 : if (TREE_CODE (neigh_tree) != SSA_NAME)
167 34547929 : return; /* Skip any neighbor that isn't an SSA name. */
168 41197202 : unsigned neigh_version = SSA_NAME_VERSION (neigh_tree);
169 :
170 : /* Skip neighbors outside the subgraph that Tarjan currently works
171 : with. */
172 41197202 : if (!vertices[neigh_version].active)
173 : return;
174 :
175 11344423 : vstate neigh_state = vertices[neigh_version].state;
176 11344423 : vstate parent_state = vertices[parent_version].state;
177 11344423 : if (parent_state == vopen) /* We're currently opening parent. */
178 : {
179 : /* Put unvisited neighbors on worklist. Update lowlink of parent
180 : vertex according to indices of neighbors present on stack. */
181 3956582 : switch (neigh_state)
182 : {
183 2791088 : case unvisited:
184 2791088 : worklist.safe_push (neigh_version);
185 2791088 : break;
186 561023 : case vopen:
187 561023 : case closed:
188 561023 : vertices[parent_version].lowlink
189 561023 : = std::min (vertices[parent_version].lowlink,
190 : vertices[neigh_version].index);
191 561023 : break;
192 : case in_scc:
193 : /* Ignore these edges. */
194 : break;
195 : }
196 : }
197 7387841 : else if (parent_state == closed) /* We're currently closing parent. */
198 : {
199 : /* Update lowlink of parent vertex according to lowlinks of
200 : children of parent (in terms of DFS tree). */
201 4120388 : if (neigh_state == closed)
202 : {
203 707500 : vertices[parent_version].lowlink
204 707500 : = std::min (vertices[parent_version].lowlink,
205 : vertices[neigh_version].lowlink);
206 : }
207 : }
208 : }
209 :
210 : /* Compute SCCs in dataflow graph on given statements 'stmts'. Ignore
211 : statements outside 'stmts'. Return the SCCs in a reverse topological
212 : order.
213 :
214 : stmt_may_generate_copy () must be true for all statements from 'stmts'! */
215 :
216 : auto_vec<vec<gimple *>>
217 10298880 : scc_discovery::compute_sccs (vec<gimple *> &stmts)
218 : {
219 10298880 : auto_vec<vec<gimple *>> sccs;
220 :
221 20341294 : for (gimple *stmt : stmts)
222 : {
223 7717960 : unsigned i;
224 7717960 : switch (gimple_code (stmt))
225 : {
226 21588 : case GIMPLE_ASSIGN:
227 21588 : i = SSA_NAME_VERSION (gimple_assign_lhs (stmt));
228 21588 : break;
229 7696372 : case GIMPLE_PHI:
230 7696372 : i = SSA_NAME_VERSION (gimple_phi_result (stmt));
231 7696372 : break;
232 0 : default:
233 0 : gcc_unreachable ();
234 : }
235 :
236 7717960 : vertices[i].index = 0;
237 7717960 : vertices[i].lowlink = 0;
238 7717960 : vertices[i].state = unvisited;
239 7717960 : vertices[i].active = true; /* Mark the subgraph we'll be working on so
240 : that we don't leave it. */
241 :
242 7717960 : worklist.safe_push (i);
243 : }
244 :
245 : /* Worklist loop. */
246 : unsigned curr_index = 0;
247 28525888 : while (!worklist.is_empty ())
248 : {
249 18227008 : unsigned i = worklist.pop ();
250 18227008 : gimple *stmt = SSA_NAME_DEF_STMT (ssa_name (i));
251 18227008 : vstate state = vertices[i].state;
252 :
253 18227008 : if (state == unvisited)
254 : {
255 7717960 : vertices[i].state = vopen;
256 :
257 : /* Assign index to this vertex. */
258 7717960 : vertices[i].index = curr_index;
259 7717960 : vertices[i].lowlink = curr_index;
260 7717960 : curr_index++;
261 :
262 : /* Put vertex on stack and also on worklist to be closed later. */
263 7717960 : stack.safe_push (i);
264 7717960 : worklist.safe_push (i);
265 : }
266 10509048 : else if (state == vopen)
267 7717960 : vertices[i].state = closed;
268 :
269 : /* Visit neighbors of this vertex. */
270 18227008 : tree op;
271 18227008 : gphi *phi;
272 18227008 : switch (gimple_code (stmt))
273 : {
274 18182792 : case GIMPLE_PHI:
275 18182792 : phi = as_a <gphi *> (stmt);
276 18182792 : unsigned j;
277 82213720 : for (j = 0; j < gimple_phi_num_args (phi); j++)
278 : {
279 45848136 : op = gimple_phi_arg_def (phi, j);
280 45848136 : visit_neighbor (op, i);
281 : }
282 : break;
283 44216 : case GIMPLE_ASSIGN:
284 44216 : op = gimple_assign_rhs1 (stmt);
285 44216 : visit_neighbor (op, i);
286 44216 : break;
287 0 : default:
288 0 : gcc_unreachable ();
289 : }
290 :
291 : /* If we've just closed a root vertex of an scc, pop scc from stack. */
292 18227008 : if (state == vopen && vertices[i].lowlink == vertices[i].index)
293 : {
294 7252183 : vec<gimple *> scc = vNULL;
295 :
296 7717960 : unsigned j;
297 7717960 : do
298 : {
299 7717960 : j = stack.pop ();
300 7717960 : scc.safe_push (SSA_NAME_DEF_STMT (ssa_name (j)));
301 7717960 : vertices[j].state = in_scc;
302 : }
303 7717960 : while (j != i);
304 :
305 7252183 : sccs.safe_push (scc);
306 : }
307 : }
308 :
309 10298880 : if (!stack.is_empty ())
310 0 : gcc_unreachable ();
311 :
312 : /* Clear 'active' flags. */
313 20341294 : for (gimple *stmt : stmts)
314 : {
315 7717960 : unsigned i;
316 7717960 : switch (gimple_code (stmt))
317 : {
318 21588 : case GIMPLE_ASSIGN:
319 21588 : i = SSA_NAME_VERSION (gimple_assign_lhs (stmt));
320 21588 : break;
321 7696372 : case GIMPLE_PHI:
322 7696372 : i = SSA_NAME_VERSION (gimple_phi_result (stmt));
323 7696372 : break;
324 0 : default:
325 0 : gcc_unreachable ();
326 : }
327 :
328 7717960 : vertices[i].active = false;
329 : }
330 :
331 10298880 : return sccs;
332 : }
333 :
334 : } // anon namespace
335 :
336 : /* Could this statement potentially be a copy statement?
337 :
338 : This pass only considers statements for which this function returns 'true'.
339 : Those are basically PHI functions and assignment statements similar to
340 :
341 : _2 = _1;
342 : or
343 : _2 = 5; */
344 :
345 : static bool
346 157822972 : stmt_may_generate_copy (gimple *stmt)
347 : {
348 : /* A PHI may generate a copy. */
349 157822972 : if (gimple_code (stmt) == GIMPLE_PHI)
350 : {
351 7894182 : gphi *phi = as_a <gphi *> (stmt);
352 :
353 : /* No OCCURS_IN_ABNORMAL_PHI SSA names in lhs nor rhs. */
354 7894182 : if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (phi)))
355 : return false;
356 :
357 : unsigned i;
358 28042343 : for (i = 0; i < gimple_phi_num_args (phi); i++)
359 : {
360 20160528 : tree op = gimple_phi_arg_def (phi, i);
361 20160528 : if (TREE_CODE (op) == SSA_NAME
362 20160528 : && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
363 : return false;
364 : }
365 :
366 : /* If PHI has more than one unique non-SSA arguments, it won't generate a
367 : copy. */
368 : tree const_op = NULL_TREE;
369 27178353 : for (i = 0; i < gimple_phi_num_args (phi); i++)
370 : {
371 19623867 : tree op = gimple_phi_arg_def (phi, i);
372 19623867 : if (TREE_CODE (op) != SSA_NAME)
373 : {
374 2646901 : if (const_op && !operand_equal_p (op, const_op))
375 : return false;
376 : const_op = op;
377 : }
378 : }
379 :
380 : return true;
381 : }
382 :
383 : /* Or a statement of type _2 = _1; OR _2 = 5; may generate a copy. */
384 :
385 149928790 : if (!gimple_assign_single_p (stmt))
386 : return false;
387 :
388 28935434 : tree lhs = gimple_assign_lhs (stmt);
389 28935434 : tree rhs = gimple_assign_rhs1 (stmt);
390 :
391 28935434 : if (TREE_CODE (lhs) != SSA_NAME)
392 : return false;
393 :
394 : /* lhs shouldn't flow through any abnormal edges. */
395 13392925 : if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
396 : return false;
397 :
398 13392265 : if (is_gimple_min_invariant (rhs))
399 : return true; /* A statement of type _2 = 5;. */
400 :
401 13386619 : if (TREE_CODE (rhs) != SSA_NAME)
402 : return false;
403 :
404 : /* rhs shouldn't flow through any abnormal edges. */
405 25404 : if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs))
406 : return false;
407 :
408 : /* It is possible that lhs has more alignment or value range information. By
409 : propagating we would lose this information. So in the case that alignment
410 : or value range information differs, we are conservative and do not
411 : propagate.
412 :
413 : FIXME: Propagate alignment and value range info the same way copy-prop
414 : does. */
415 47210 : if (POINTER_TYPE_P (TREE_TYPE (lhs))
416 1475 : && POINTER_TYPE_P (TREE_TYPE (rhs))
417 25793 : && SSA_NAME_PTR_INFO (lhs) != SSA_NAME_PTR_INFO (rhs))
418 : return false;
419 45874 : if (!POINTER_TYPE_P (TREE_TYPE (lhs))
420 22843 : && !POINTER_TYPE_P (TREE_TYPE (rhs))
421 45874 : && SSA_NAME_RANGE_INFO (lhs) != SSA_NAME_RANGE_INFO (rhs))
422 : return false;
423 :
424 : return true; /* A statement of type _2 = _1;. */
425 : }
426 :
427 : /* Return all statements in cfun that could generate copies. All statements
428 : for which stmt_may_generate_copy returns 'true'. */
429 :
430 : static auto_vec<gimple *>
431 3453819 : get_all_stmt_may_generate_copy (void)
432 : {
433 3453819 : auto_vec<gimple *> result;
434 :
435 3453819 : basic_block bb;
436 24394623 : FOR_EACH_BB_FN (bb, cfun)
437 : {
438 20940804 : gimple_stmt_iterator gsi;
439 191810398 : for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
440 : {
441 149928790 : gimple *s = gsi_stmt (gsi);
442 149928790 : if (stmt_may_generate_copy (s))
443 21588 : result.safe_push (s);
444 : }
445 :
446 20940804 : gphi_iterator pi;
447 28834986 : for (pi = gsi_start_phis (bb); !gsi_end_p (pi); gsi_next (&pi))
448 : {
449 7894182 : gimple *s = pi.phi ();
450 7894182 : if (stmt_may_generate_copy (s))
451 7554486 : result.safe_push (s);
452 : }
453 : }
454 :
455 3453819 : return result;
456 : }
457 :
458 : /* SCC copy propagation
459 :
460 : 'scc_copy_prop::propagate ()' is the main function of this pass. */
461 :
462 : class scc_copy_prop
463 : {
464 : public:
465 : scc_copy_prop ();
466 : ~scc_copy_prop ();
467 : bool propagate ();
468 :
469 : private:
470 : /* Bitmap tracking statements which were propagated so that they can be
471 : removed at the end of the pass. */
472 : bitmap dead_stmts;
473 :
474 : void visit_op (tree op, hash_set<tree> &outer_ops,
475 : hash_set<gimple *> &scc_set, bool &is_inner,
476 : tree &last_outer_op);
477 : bool replace_scc_by_value (vec<gimple *> scc, tree val);
478 : };
479 :
480 : /* For each statement from given SCC, replace its usages by value
481 : VAL. */
482 :
483 : bool
484 407122 : scc_copy_prop::replace_scc_by_value (vec<gimple *> scc, tree val)
485 : {
486 407122 : bool didsomething = false;
487 1633339 : for (gimple *stmt : scc)
488 : {
489 411973 : tree name = gimple_get_lhs (stmt);
490 411973 : if (dump_file && (dump_flags & TDF_DETAILS))
491 : {
492 0 : fprintf (dump_file, "Replacing ");
493 0 : print_generic_expr (dump_file, name);
494 0 : fprintf (dump_file, " with ");
495 0 : print_generic_expr (dump_file, val);
496 0 : fprintf (dump_file, "\n");
497 :
498 : }
499 411973 : replace_uses_by (name, val);
500 411973 : bitmap_set_bit (dead_stmts, SSA_NAME_VERSION (name));
501 411973 : didsomething = true;
502 : }
503 :
504 407122 : if (dump_file)
505 56 : fprintf (dump_file, "Replacing SCC of size %d\n", scc.length ());
506 407122 : return didsomething;
507 : }
508 :
509 : /* Part of 'scc_copy_prop::propagate ()'. */
510 :
511 : void
512 19242025 : scc_copy_prop::visit_op (tree op, hash_set<tree> &outer_ops,
513 : hash_set<gimple *> &scc_set, bool &is_inner,
514 : tree &last_outer_op)
515 : {
516 19242025 : bool op_in_scc = false;
517 :
518 19242025 : if (TREE_CODE (op) == SSA_NAME)
519 : {
520 17261806 : gimple *op_stmt = SSA_NAME_DEF_STMT (op);
521 17261806 : if (scc_set.contains (op_stmt))
522 1133246 : op_in_scc = true;
523 : }
524 :
525 17261806 : if (!op_in_scc)
526 : {
527 18108779 : outer_ops.add (op);
528 18108779 : last_outer_op = op;
529 18108779 : is_inner = false;
530 : }
531 19242025 : }
532 :
533 : /* Main function of this pass. Find and propagate all three types of copy
534 : statements (see pass description above).
535 :
536 : This is an implementation of an algorithm from the paper Simple and
537 : Efficient Construction of Static Single Assignmemnt Form[1]. It is based
538 : on strongly-connected components (SCCs) in dataflow graph. The original
539 : algorithm only considers PHI statements. We extend it to also consider
540 : assignment statements of type _2 = _1;.
541 :
542 : The algorithm is based on this definition of a set of redundant PHIs[1]:
543 :
544 : A non-empty set P of PHI functions is redundant iff the PHI functions just
545 : reference each other or one other value
546 :
547 : It uses this lemma[1]:
548 :
549 : Let P be a redundant set of PHI functions. Then there is a
550 : strongly-connected component S subset of P that is also redundant.
551 :
552 : The algorithm works in this way:
553 :
554 : 1 Find SCCs
555 : 2 For each SCC S in topological order:
556 : 3 Construct set 'inner' of statements that only have other statements
557 : from S on their right hand side
558 : 4 Construct set 'outer' of values that originate outside S and appear on
559 : right hand side of some statement from S
560 : 5 If |outer| = 1, outer only contains a value v. Statements in S only
561 : refer to each other or to v -- they are redundant. Propagate v.
562 : Else, recurse on statements in inner.
563 :
564 : The implementation is non-recursive.
565 :
566 : References:
567 :
568 : [1] Simple and Efficient Construction of Static Single Assignmemnt Form,
569 : Braun, Buchwald, Hack, Leissa, Mallon, Zwinkau, 2013, LNCS vol. 7791,
570 : Section 3.2. */
571 :
572 : bool
573 3453819 : scc_copy_prop::propagate ()
574 : {
575 3453819 : bool didsomething = false;
576 3453819 : auto_vec<gimple *> useful_stmts = get_all_stmt_may_generate_copy ();
577 3453819 : scc_discovery discovery;
578 :
579 3453819 : auto_vec<vec<gimple *>> worklist = discovery.compute_sccs (useful_stmts);
580 :
581 14159821 : while (!worklist.is_empty ())
582 : {
583 7252183 : vec<gimple *> scc = worklist.pop ();
584 :
585 : /* When we do 'replace_scc_by_value' it may happen that some EH edges
586 : get removed. That means parts of CFG get removed. Those may
587 : contain copy statements. For that reason we prune SCCs here. */
588 7252183 : unsigned i;
589 14970143 : for (i = 0; i < scc.length ();)
590 7717960 : if (gimple_bb (scc[i]) == NULL)
591 0 : scc.unordered_remove (i);
592 : else
593 7717960 : i++;
594 7252183 : if (scc.is_empty ())
595 : {
596 0 : scc.release ();
597 0 : continue;
598 : }
599 :
600 7252183 : auto_vec<gimple *> inner;
601 7252183 : hash_set<tree> outer_ops;
602 7252183 : tree last_outer_op = NULL_TREE;
603 :
604 : /* Prepare hash set of PHIs in scc to query later. */
605 7252183 : hash_set<gimple *> scc_set;
606 14970143 : for (gimple *stmt : scc)
607 7717960 : scc_set.add (stmt);
608 :
609 14970143 : for (gimple *stmt : scc)
610 : {
611 7717960 : bool is_inner = true;
612 :
613 7717960 : gphi *phi;
614 7717960 : tree op;
615 :
616 7717960 : switch (gimple_code (stmt))
617 : {
618 7696372 : case GIMPLE_PHI:
619 7696372 : phi = as_a <gphi *> (stmt);
620 7696372 : unsigned j;
621 34613181 : for (j = 0; j < gimple_phi_num_args (phi); j++)
622 : {
623 19220437 : op = gimple_phi_arg_def (phi, j);
624 19220437 : visit_op (op, outer_ops, scc_set, is_inner, last_outer_op);
625 : }
626 : break;
627 21588 : case GIMPLE_ASSIGN:
628 21588 : op = gimple_assign_rhs1 (stmt);
629 21588 : visit_op (op, outer_ops, scc_set, is_inner, last_outer_op);
630 21588 : break;
631 0 : default:
632 0 : gcc_unreachable ();
633 : }
634 :
635 7717960 : if (is_inner)
636 146214 : inner.safe_push (stmt);
637 : }
638 :
639 7252183 : if (outer_ops.elements () == 1)
640 : {
641 : /* The only operand in outer_ops. */
642 407122 : tree outer_op = last_outer_op;
643 407122 : didsomething |= replace_scc_by_value (scc, outer_op);
644 : }
645 6845061 : else if (outer_ops.elements () > 1)
646 : {
647 : /* Add inner sccs to worklist. */
648 6845061 : auto_vec<vec<gimple *>> inner_sccs
649 6845061 : = discovery.compute_sccs (inner);
650 7105400 : for (vec<gimple *> inner_scc : inner_sccs)
651 114627 : worklist.safe_push (inner_scc);
652 6845061 : }
653 : else
654 0 : gcc_unreachable ();
655 :
656 7252183 : scc.release ();
657 7252183 : }
658 3453819 : return didsomething;
659 3453819 : }
660 :
661 3453819 : scc_copy_prop::scc_copy_prop ()
662 : {
663 : /* For propagated statements. */
664 3453819 : dead_stmts = BITMAP_ALLOC (NULL);
665 3453819 : }
666 :
667 3453819 : scc_copy_prop::~scc_copy_prop ()
668 : {
669 : /* Remove all propagated statements. */
670 3453819 : simple_dce_from_worklist (dead_stmts);
671 3453819 : BITMAP_FREE (dead_stmts);
672 :
673 : /* Propagating a constant may create dead eh edges. */
674 3453819 : basic_block bb;
675 24394623 : FOR_EACH_BB_FN (bb, cfun)
676 20940804 : gimple_purge_dead_eh_edges (bb);
677 3453819 : }
678 :
679 : namespace {
680 :
681 : const pass_data pass_data_sccopy =
682 : {
683 : GIMPLE_PASS, /* type */
684 : "sccopy", /* name */
685 : OPTGROUP_NONE, /* optinfo_flags */
686 : TV_NONE, /* tv_id */
687 : ( PROP_cfg | PROP_ssa ), /* properties_required */
688 : 0, /* properties_provided */
689 : 0, /* properties_destroyed */
690 : 0, /* todo_flags_start */
691 : 0, /* todo_flags_finish */
692 : };
693 :
694 : class pass_sccopy : public gimple_opt_pass
695 : {
696 : public:
697 571444 : pass_sccopy (gcc::context *ctxt)
698 1142888 : : gimple_opt_pass (pass_data_sccopy, ctxt)
699 : {}
700 :
701 : /* opt_pass methods: */
702 3453912 : virtual bool gate (function *) final override { return true; }
703 : virtual unsigned int execute (function *) final override;
704 285722 : opt_pass * clone () final override { return new pass_sccopy (m_ctxt); }
705 : }; // class pass_sccopy
706 :
707 : unsigned
708 3453819 : pass_sccopy::execute (function *)
709 : {
710 3453819 : scc_copy_prop sccopy;
711 3453819 : return sccopy.propagate () ? TODO_cleanup_cfg : 0;
712 3453819 : }
713 :
714 : } // anon namespace
715 :
716 : gimple_opt_pass *
717 285722 : make_pass_sccopy (gcc::context *ctxt)
718 : {
719 285722 : return new pass_sccopy (ctxt);
720 : }
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