1 | /* Strongly-connected copy propagation pass for the GNU compiler. |
2 | Copyright (C) 2023-2024 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 | |
42 | /* Strongly connected copy propagation pass. |
43 | |
44 | This is a lightweight copy propagation pass that is also able to eliminate |
45 | redundant PHI statements. The pass considers the following types of copy |
46 | statements: |
47 | |
48 | 1 An assignment statement with a single argument. |
49 | |
50 | _3 = _2; |
51 | _4 = 5; |
52 | |
53 | 2 A degenerate PHI statement. A degenerate PHI is a PHI that only refers to |
54 | itself or one other value. |
55 | |
56 | _5 = PHI <_1>; |
57 | _6 = PHI <_6, _6, _1, _1>; |
58 | _7 = PHI <16, _7>; |
59 | |
60 | 3 A set of PHI statements that only refer to each other or to one other |
61 | value. |
62 | |
63 | _8 = PHI <_9, _10>; |
64 | _9 = PHI <_8, _10>; |
65 | _10 = PHI <_8, _9, _1>; |
66 | |
67 | All of these statements produce copies and can be eliminated from the |
68 | program. For a copy statement we identify the value it creates a copy of |
69 | and replace references to the statement with the value -- we propagate the |
70 | copy. |
71 | |
72 | _3 = _2; // Replace all occurences of _3 by _2 |
73 | |
74 | _8 = PHI <_9, _10>; |
75 | _9 = PHI <_8, _10>; |
76 | _10 = PHI <_8, _9, _1>; // Replace all occurences of _8, _9 and _10 by _1 |
77 | |
78 | To find all three types of copy statements we use an algorithm based on |
79 | strongly-connected components (SCCs) in dataflow graph. The algorithm was |
80 | introduced in an article from 2013[1]. We describe the algorithm bellow. |
81 | |
82 | To identify SCCs we implement the Robert Tarjan's SCC algorithm. For the |
83 | SCC computation we wrap potential copy statements in the 'vertex' struct. |
84 | To each of these statements we also assign a vertex number ('vxnum'). Since |
85 | the main algorithm has to be able to compute SCCs of subgraphs of the whole |
86 | dataflow graph we use GIMPLE stmt flags to prevent Tarjan's algorithm from |
87 | leaving the subgraph. |
88 | |
89 | References: |
90 | |
91 | [1] Simple and Efficient Construction of Static Single Assignmemnt Form, |
92 | Braun, Buchwald, Hack, Leissa, Mallon, Zwinkau, 2013, LNCS vol. 7791, |
93 | Section 3.2. */ |
94 | |
95 | /* Bitmap tracking statements which were propagated to be removed at the end of |
96 | the pass. */ |
97 | |
98 | namespace { |
99 | static bitmap dead_stmts; |
100 | |
101 | /* State of vertex during SCC discovery. |
102 | |
103 | unvisited Vertex hasn't yet been popped from worklist. |
104 | vopen DFS has visited vertex for the first time. Vertex has been put |
105 | on Tarjan stack. |
106 | closed DFS has backtracked through vertex. At this point, vertex |
107 | doesn't have any unvisited neighbors. |
108 | in_scc Vertex has been popped from Tarjan stack. */ |
109 | |
110 | enum vstate |
111 | { |
112 | unvisited, |
113 | vopen, |
114 | closed, |
115 | in_scc |
116 | }; |
117 | |
118 | /* Information about a vertex. Used by SCC discovery. */ |
119 | |
120 | struct vertex |
121 | { |
122 | bool active; /* scc_discovery::compute_sccs () only considers a subgraph of |
123 | the whole dataflow graph. It uses this flag so that it knows |
124 | which vertices are part of this subgraph. */ |
125 | vstate state; |
126 | unsigned index; |
127 | unsigned lowlink; |
128 | }; |
129 | |
130 | /* SCC discovery. |
131 | |
132 | Used to find SCCs in a dataflow graph. Implements Tarjan's SCC |
133 | algorithm. */ |
134 | |
135 | class scc_discovery |
136 | { |
137 | public: |
138 | scc_discovery (); |
139 | ~scc_discovery (); |
140 | auto_vec<vec<gimple *>> compute_sccs (vec<gimple *> &stmts); |
141 | |
142 | private: |
143 | vertex* vertices; /* Indexed by SSA_NAME_VERSION. */ |
144 | auto_vec<unsigned> worklist; /* DFS stack. */ |
145 | auto_vec<unsigned> stack; /* Tarjan stack. */ |
146 | |
147 | void visit_neighbor (tree neigh_tree, unsigned parent_vxnum); |
148 | }; |
149 | |
150 | scc_discovery::scc_discovery () |
151 | { |
152 | /* Create vertex struct for each SSA name. */ |
153 | vertices = XNEWVEC (struct vertex, num_ssa_names); |
154 | unsigned i = 0; |
155 | for (i = 0; i < num_ssa_names; i++) |
156 | vertices[i].active = false; |
157 | } |
158 | |
159 | scc_discovery::~scc_discovery () |
160 | { |
161 | XDELETEVEC (vertices); |
162 | } |
163 | |
164 | /* Part of 'scc_discovery::compute_sccs ()'. */ |
165 | |
166 | void |
167 | scc_discovery::visit_neighbor (tree neigh_tree, unsigned parent_version) |
168 | { |
169 | if (TREE_CODE (neigh_tree) != SSA_NAME) |
170 | return; /* Skip any neighbor that isn't an SSA name. */ |
171 | unsigned neigh_version = SSA_NAME_VERSION (neigh_tree); |
172 | |
173 | /* Skip neighbors outside the subgraph that Tarjan currently works |
174 | with. */ |
175 | if (!vertices[neigh_version].active) |
176 | return; |
177 | |
178 | vstate neigh_state = vertices[neigh_version].state; |
179 | vstate parent_state = vertices[parent_version].state; |
180 | if (parent_state == vopen) /* We're currently opening parent. */ |
181 | { |
182 | /* Put unvisited neighbors on worklist. Update lowlink of parent |
183 | vertex according to indices of neighbors present on stack. */ |
184 | switch (neigh_state) |
185 | { |
186 | case unvisited: |
187 | worklist.safe_push (obj: neigh_version); |
188 | break; |
189 | case vopen: |
190 | case closed: |
191 | vertices[parent_version].lowlink |
192 | = std::min (a: vertices[parent_version].lowlink, |
193 | b: vertices[neigh_version].index); |
194 | break; |
195 | case in_scc: |
196 | /* Ignore these edges. */ |
197 | break; |
198 | } |
199 | } |
200 | else if (parent_state == closed) /* We're currently closing parent. */ |
201 | { |
202 | /* Update lowlink of parent vertex according to lowlinks of |
203 | children of parent (in terms of DFS tree). */ |
204 | if (neigh_state == closed) |
205 | { |
206 | vertices[parent_version].lowlink |
207 | = std::min (a: vertices[parent_version].lowlink, |
208 | b: vertices[neigh_version].lowlink); |
209 | } |
210 | } |
211 | } |
212 | |
213 | /* Compute SCCs in dataflow graph on given statements 'stmts'. Ignore |
214 | statements outside 'stmts'. Return the SCCs in a reverse topological |
215 | order. |
216 | |
217 | stmt_may_generate_copy () must be true for all statements from 'stmts'! */ |
218 | |
219 | auto_vec<vec<gimple *>> |
220 | scc_discovery::compute_sccs (vec<gimple *> &stmts) |
221 | { |
222 | auto_vec<vec<gimple *>> sccs; |
223 | |
224 | for (gimple *stmt : stmts) |
225 | { |
226 | unsigned i; |
227 | switch (gimple_code (g: stmt)) |
228 | { |
229 | case GIMPLE_ASSIGN: |
230 | i = SSA_NAME_VERSION (gimple_assign_lhs (stmt)); |
231 | break; |
232 | case GIMPLE_PHI: |
233 | i = SSA_NAME_VERSION (gimple_phi_result (stmt)); |
234 | break; |
235 | default: |
236 | gcc_unreachable (); |
237 | } |
238 | |
239 | vertices[i].index = 0; |
240 | vertices[i].lowlink = 0; |
241 | vertices[i].state = unvisited; |
242 | vertices[i].active = true; /* Mark the subgraph we'll be working on so |
243 | that we don't leave it. */ |
244 | |
245 | worklist.safe_push (obj: i); |
246 | } |
247 | |
248 | /* Worklist loop. */ |
249 | unsigned curr_index = 0; |
250 | while (!worklist.is_empty ()) |
251 | { |
252 | unsigned i = worklist.pop (); |
253 | gimple *stmt = SSA_NAME_DEF_STMT (ssa_name (i)); |
254 | vstate state = vertices[i].state; |
255 | |
256 | if (state == unvisited) |
257 | { |
258 | vertices[i].state = vopen; |
259 | |
260 | /* Assign index to this vertex. */ |
261 | vertices[i].index = curr_index; |
262 | vertices[i].lowlink = curr_index; |
263 | curr_index++; |
264 | |
265 | /* Put vertex on stack and also on worklist to be closed later. */ |
266 | stack.safe_push (obj: i); |
267 | worklist.safe_push (obj: i); |
268 | } |
269 | else if (state == vopen) |
270 | vertices[i].state = closed; |
271 | |
272 | /* Visit neighbors of this vertex. */ |
273 | tree op; |
274 | gphi *phi; |
275 | switch (gimple_code (g: stmt)) |
276 | { |
277 | case GIMPLE_PHI: |
278 | phi = as_a <gphi *> (p: stmt); |
279 | unsigned j; |
280 | for (j = 0; j < gimple_phi_num_args (gs: phi); j++) |
281 | { |
282 | op = gimple_phi_arg_def (gs: phi, index: j); |
283 | visit_neighbor (neigh_tree: op, parent_version: i); |
284 | } |
285 | break; |
286 | case GIMPLE_ASSIGN: |
287 | op = gimple_assign_rhs1 (gs: stmt); |
288 | visit_neighbor (neigh_tree: op, parent_version: i); |
289 | break; |
290 | default: |
291 | gcc_unreachable (); |
292 | } |
293 | |
294 | /* If we've just closed a root vertex of an scc, pop scc from stack. */ |
295 | if (state == vopen && vertices[i].lowlink == vertices[i].index) |
296 | { |
297 | vec<gimple *> scc = vNULL; |
298 | |
299 | unsigned j; |
300 | do |
301 | { |
302 | j = stack.pop (); |
303 | scc.safe_push (SSA_NAME_DEF_STMT (ssa_name (j))); |
304 | vertices[j].state = in_scc; |
305 | } |
306 | while (j != i); |
307 | |
308 | sccs.safe_push (obj: scc); |
309 | } |
310 | } |
311 | |
312 | if (!stack.is_empty ()) |
313 | gcc_unreachable (); |
314 | |
315 | /* Clear 'active' flags. */ |
316 | for (gimple *stmt : stmts) |
317 | { |
318 | unsigned i; |
319 | switch (gimple_code (g: stmt)) |
320 | { |
321 | case GIMPLE_ASSIGN: |
322 | i = SSA_NAME_VERSION (gimple_assign_lhs (stmt)); |
323 | break; |
324 | case GIMPLE_PHI: |
325 | i = SSA_NAME_VERSION (gimple_phi_result (stmt)); |
326 | break; |
327 | default: |
328 | gcc_unreachable (); |
329 | } |
330 | |
331 | vertices[i].active = false; |
332 | } |
333 | |
334 | return sccs; |
335 | } |
336 | |
337 | } // anon namespace |
338 | |
339 | /* Could this statement potentially be a copy statement? |
340 | |
341 | This pass only considers statements for which this function returns 'true'. |
342 | Those are basically PHI functions and assignment statements similar to |
343 | |
344 | _2 = _1; |
345 | or |
346 | _2 = 5; */ |
347 | |
348 | static bool |
349 | stmt_may_generate_copy (gimple *stmt) |
350 | { |
351 | /* A PHI may generate a copy. */ |
352 | if (gimple_code (g: stmt) == GIMPLE_PHI) |
353 | { |
354 | gphi *phi = as_a <gphi *> (p: stmt); |
355 | |
356 | /* No OCCURS_IN_ABNORMAL_PHI SSA names in lhs nor rhs. */ |
357 | if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (phi))) |
358 | return false; |
359 | |
360 | unsigned i; |
361 | for (i = 0; i < gimple_phi_num_args (gs: phi); i++) |
362 | { |
363 | tree op = gimple_phi_arg_def (gs: phi, index: i); |
364 | if (TREE_CODE (op) == SSA_NAME |
365 | && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op)) |
366 | return false; |
367 | } |
368 | |
369 | /* If PHI has more than one unique non-SSA arguments, it won't generate a |
370 | copy. */ |
371 | tree const_op = NULL_TREE; |
372 | for (i = 0; i < gimple_phi_num_args (gs: phi); i++) |
373 | { |
374 | tree op = gimple_phi_arg_def (gs: phi, index: i); |
375 | if (TREE_CODE (op) != SSA_NAME) |
376 | { |
377 | if (const_op && !operand_equal_p (op, const_op)) |
378 | return false; |
379 | const_op = op; |
380 | } |
381 | } |
382 | |
383 | return true; |
384 | } |
385 | |
386 | /* Or a statement of type _2 = _1; OR _2 = 5; may generate a copy. */ |
387 | |
388 | if (!gimple_assign_single_p (gs: stmt)) |
389 | return false; |
390 | |
391 | tree lhs = gimple_assign_lhs (gs: stmt); |
392 | tree rhs = gimple_assign_rhs1 (gs: stmt); |
393 | |
394 | if (TREE_CODE (lhs) != SSA_NAME) |
395 | return false; |
396 | |
397 | /* lhs shouldn't flow through any abnormal edges. */ |
398 | if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs)) |
399 | return false; |
400 | |
401 | if (is_gimple_min_invariant (rhs)) |
402 | return true; /* A statement of type _2 = 5;. */ |
403 | |
404 | if (TREE_CODE (rhs) != SSA_NAME) |
405 | return false; |
406 | |
407 | /* rhs shouldn't flow through any abnormal edges. */ |
408 | if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs)) |
409 | return false; |
410 | |
411 | /* It is possible that lhs has more alignment or value range information. By |
412 | propagating we would lose this information. So in the case that alignment |
413 | or value range information differs, we are conservative and do not |
414 | propagate. |
415 | |
416 | FIXME: Propagate alignment and value range info the same way copy-prop |
417 | does. */ |
418 | if (POINTER_TYPE_P (TREE_TYPE (lhs)) |
419 | && POINTER_TYPE_P (TREE_TYPE (rhs)) |
420 | && SSA_NAME_PTR_INFO (lhs) != SSA_NAME_PTR_INFO (rhs)) |
421 | return false; |
422 | if (!POINTER_TYPE_P (TREE_TYPE (lhs)) |
423 | && !POINTER_TYPE_P (TREE_TYPE (rhs)) |
424 | && SSA_NAME_RANGE_INFO (lhs) != SSA_NAME_RANGE_INFO (rhs)) |
425 | return false; |
426 | |
427 | return true; /* A statement of type _2 = _1;. */ |
428 | } |
429 | |
430 | /* Return all statements in cfun that could generate copies. All statements |
431 | for which stmt_may_generate_copy returns 'true'. */ |
432 | |
433 | static auto_vec<gimple *> |
434 | get_all_stmt_may_generate_copy (void) |
435 | { |
436 | auto_vec<gimple *> result; |
437 | |
438 | basic_block bb; |
439 | FOR_EACH_BB_FN (bb, cfun) |
440 | { |
441 | gimple_stmt_iterator gsi; |
442 | for (gsi = gsi_start_bb (bb); !gsi_end_p (i: gsi); gsi_next (i: &gsi)) |
443 | { |
444 | gimple *s = gsi_stmt (i: gsi); |
445 | if (stmt_may_generate_copy (stmt: s)) |
446 | result.safe_push (obj: s); |
447 | } |
448 | |
449 | gphi_iterator pi; |
450 | for (pi = gsi_start_phis (bb); !gsi_end_p (i: pi); gsi_next (i: &pi)) |
451 | { |
452 | gimple *s = pi.phi (); |
453 | if (stmt_may_generate_copy (stmt: s)) |
454 | result.safe_push (obj: s); |
455 | } |
456 | } |
457 | |
458 | return result; |
459 | } |
460 | |
461 | /* For each statement from given SCC, replace its usages by value |
462 | VAL. */ |
463 | |
464 | static void |
465 | replace_scc_by_value (vec<gimple *> scc, tree val) |
466 | { |
467 | for (gimple *stmt : scc) |
468 | { |
469 | tree name = gimple_get_lhs (stmt); |
470 | replace_uses_by (name, val); |
471 | bitmap_set_bit (dead_stmts, SSA_NAME_VERSION (name)); |
472 | } |
473 | |
474 | if (dump_file) |
475 | fprintf (stream: dump_file, format: "Replacing SCC of size %d\n" , scc.length ()); |
476 | } |
477 | |
478 | /* Part of 'sccopy_propagate ()'. */ |
479 | |
480 | static void |
481 | sccopy_visit_op (tree op, hash_set<tree> &outer_ops, |
482 | hash_set<gimple *> &scc_set, bool &is_inner, |
483 | tree &last_outer_op) |
484 | { |
485 | bool op_in_scc = false; |
486 | |
487 | if (TREE_CODE (op) == SSA_NAME) |
488 | { |
489 | gimple *op_stmt = SSA_NAME_DEF_STMT (op); |
490 | if (scc_set.contains (k: op_stmt)) |
491 | op_in_scc = true; |
492 | } |
493 | |
494 | if (!op_in_scc) |
495 | { |
496 | outer_ops.add (k: op); |
497 | last_outer_op = op; |
498 | is_inner = false; |
499 | } |
500 | } |
501 | |
502 | /* Main function of this pass. Find and propagate all three types of copy |
503 | statements (see pass description above). |
504 | |
505 | This is an implementation of an algorithm from the paper Simple and |
506 | Efficient Construction of Static Single Assignmemnt Form[1]. It is based |
507 | on strongly-connected components (SCCs) in dataflow graph. The original |
508 | algorithm only considers PHI statements. We extend it to also consider |
509 | assignment statements of type _2 = _1;. |
510 | |
511 | The algorithm is based on this definition of a set of redundant PHIs[1]: |
512 | |
513 | A non-empty set P of PHI functions is redundant iff the PHI functions just |
514 | reference each other or one other value |
515 | |
516 | It uses this lemma[1]: |
517 | |
518 | Let P be a redundant set of PHI functions. Then there is a |
519 | strongly-connected component S subset of P that is also redundant. |
520 | |
521 | The algorithm works in this way: |
522 | |
523 | 1 Find SCCs |
524 | 2 For each SCC S in topological order: |
525 | 3 Construct set 'inner' of statements that only have other statements |
526 | from S on their right hand side |
527 | 4 Construct set 'outer' of values that originate outside S and appear on |
528 | right hand side of some statement from S |
529 | 5 If |outer| = 1, outer only contains a value v. Statements in S only |
530 | refer to each other or to v -- they are redundant. Propagate v. |
531 | Else, recurse on statements in inner. |
532 | |
533 | The implementation is non-recursive. |
534 | |
535 | References: |
536 | |
537 | [1] Simple and Efficient Construction of Static Single Assignmemnt Form, |
538 | Braun, Buchwald, Hack, Leissa, Mallon, Zwinkau, 2013, LNCS vol. 7791, |
539 | Section 3.2. */ |
540 | |
541 | static void |
542 | sccopy_propagate () |
543 | { |
544 | auto_vec<gimple *> useful_stmts = get_all_stmt_may_generate_copy (); |
545 | scc_discovery discovery; |
546 | |
547 | auto_vec<vec<gimple *>> worklist = discovery.compute_sccs (stmts&: useful_stmts); |
548 | |
549 | while (!worklist.is_empty ()) |
550 | { |
551 | vec<gimple *> scc = worklist.pop (); |
552 | |
553 | auto_vec<gimple *> inner; |
554 | hash_set<tree> outer_ops; |
555 | tree last_outer_op = NULL_TREE; |
556 | |
557 | /* Prepare hash set of PHIs in scc to query later. */ |
558 | hash_set<gimple *> scc_set; |
559 | for (gimple *stmt : scc) |
560 | scc_set.add (k: stmt); |
561 | |
562 | for (gimple *stmt : scc) |
563 | { |
564 | bool is_inner = true; |
565 | |
566 | gphi *phi; |
567 | tree op; |
568 | |
569 | switch (gimple_code (g: stmt)) |
570 | { |
571 | case GIMPLE_PHI: |
572 | phi = as_a <gphi *> (p: stmt); |
573 | unsigned j; |
574 | for (j = 0; j < gimple_phi_num_args (gs: phi); j++) |
575 | { |
576 | op = gimple_phi_arg_def (gs: phi, index: j); |
577 | sccopy_visit_op (op, outer_ops, scc_set, is_inner, |
578 | last_outer_op); |
579 | } |
580 | break; |
581 | case GIMPLE_ASSIGN: |
582 | op = gimple_assign_rhs1 (gs: stmt); |
583 | sccopy_visit_op (op, outer_ops, scc_set, is_inner, |
584 | last_outer_op); |
585 | break; |
586 | default: |
587 | gcc_unreachable (); |
588 | } |
589 | |
590 | if (is_inner) |
591 | inner.safe_push (obj: stmt); |
592 | } |
593 | |
594 | if (outer_ops.elements () == 1) |
595 | { |
596 | /* The only operand in outer_ops. */ |
597 | tree outer_op = last_outer_op; |
598 | replace_scc_by_value (scc, val: outer_op); |
599 | } |
600 | else if (outer_ops.elements () > 1) |
601 | { |
602 | /* Add inner sccs to worklist. */ |
603 | auto_vec<vec<gimple *>> inner_sccs |
604 | = discovery.compute_sccs (stmts&: inner); |
605 | for (vec<gimple *> inner_scc : inner_sccs) |
606 | worklist.safe_push (obj: inner_scc); |
607 | } |
608 | else |
609 | gcc_unreachable (); |
610 | |
611 | scc.release (); |
612 | } |
613 | } |
614 | |
615 | /* Called when pass execution starts. */ |
616 | |
617 | static void |
618 | init_sccopy (void) |
619 | { |
620 | /* For propagated statements. */ |
621 | dead_stmts = BITMAP_ALLOC (NULL); |
622 | } |
623 | |
624 | /* Called before pass execution ends. */ |
625 | |
626 | static void |
627 | finalize_sccopy (void) |
628 | { |
629 | /* Remove all propagated statements. */ |
630 | simple_dce_from_worklist (dead_stmts); |
631 | BITMAP_FREE (dead_stmts); |
632 | |
633 | /* Propagating a constant may create dead eh edges. */ |
634 | basic_block bb; |
635 | FOR_EACH_BB_FN (bb, cfun) |
636 | gimple_purge_dead_eh_edges (bb); |
637 | } |
638 | |
639 | namespace { |
640 | |
641 | const pass_data pass_data_sccopy = |
642 | { |
643 | .type: GIMPLE_PASS, /* type */ |
644 | .name: "sccopy" , /* name */ |
645 | .optinfo_flags: OPTGROUP_NONE, /* optinfo_flags */ |
646 | .tv_id: TV_NONE, /* tv_id */ |
647 | .properties_required: ( PROP_cfg | PROP_ssa ), /* properties_required */ |
648 | .properties_provided: 0, /* properties_provided */ |
649 | .properties_destroyed: 0, /* properties_destroyed */ |
650 | .todo_flags_start: 0, /* todo_flags_start */ |
651 | TODO_update_ssa | TODO_cleanup_cfg, /* todo_flags_finish */ |
652 | }; |
653 | |
654 | class pass_sccopy : public gimple_opt_pass |
655 | { |
656 | public: |
657 | pass_sccopy (gcc::context *ctxt) |
658 | : gimple_opt_pass (pass_data_sccopy, ctxt) |
659 | {} |
660 | |
661 | /* opt_pass methods: */ |
662 | virtual bool gate (function *) { return true; } |
663 | virtual unsigned int execute (function *); |
664 | opt_pass * clone () final override { return new pass_sccopy (m_ctxt); } |
665 | }; // class pass_sccopy |
666 | |
667 | unsigned |
668 | pass_sccopy::execute (function *) |
669 | { |
670 | init_sccopy (); |
671 | sccopy_propagate (); |
672 | finalize_sccopy (); |
673 | return 0; |
674 | } |
675 | |
676 | } // anon namespace |
677 | |
678 | gimple_opt_pass * |
679 | make_pass_sccopy (gcc::context *ctxt) |
680 | { |
681 | return new pass_sccopy (ctxt); |
682 | } |
683 | |