1 | /* Copy propagation and SSA_NAME replacement support routines. |
2 | Copyright (C) 2004-2017 Free Software Foundation, Inc. |
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 |
8 | the Free Software Foundation; either version 3, or (at your option) |
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 |
17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ |
19 | |
20 | #include "config.h" |
21 | #include "system.h" |
22 | #include "coretypes.h" |
23 | #include "backend.h" |
24 | #include "tree.h" |
25 | #include "gimple.h" |
26 | #include "tree-pass.h" |
27 | #include "ssa.h" |
28 | #include "gimple-pretty-print.h" |
29 | #include "fold-const.h" |
30 | #include "gimple-iterator.h" |
31 | #include "tree-cfg.h" |
32 | #include "tree-ssa-propagate.h" |
33 | #include "cfgloop.h" |
34 | #include "tree-scalar-evolution.h" |
35 | #include "tree-ssa-loop-niter.h" |
36 | |
37 | |
38 | /* This file implements the copy propagation pass and provides a |
39 | handful of interfaces for performing const/copy propagation and |
40 | simple expression replacement which keep variable annotations |
41 | up-to-date. |
42 | |
43 | We require that for any copy operation where the RHS and LHS have |
44 | a non-null memory tag the memory tag be the same. It is OK |
45 | for one or both of the memory tags to be NULL. |
46 | |
47 | We also require tracking if a variable is dereferenced in a load or |
48 | store operation. |
49 | |
50 | We enforce these requirements by having all copy propagation and |
51 | replacements of one SSA_NAME with a different SSA_NAME to use the |
52 | APIs defined in this file. */ |
53 | |
54 | /*--------------------------------------------------------------------------- |
55 | Copy propagation |
56 | ---------------------------------------------------------------------------*/ |
57 | /* Lattice for copy-propagation. The lattice is initialized to |
58 | UNDEFINED (value == NULL) for SSA names that can become a copy |
59 | of something or VARYING (value == self) if not (see get_copy_of_val |
60 | and stmt_may_generate_copy). Other values make the name a COPY |
61 | of that value. |
62 | |
63 | When visiting a statement or PHI node the lattice value for an |
64 | SSA name can transition from UNDEFINED to COPY to VARYING. */ |
65 | |
66 | struct prop_value_t { |
67 | /* Copy-of value. */ |
68 | tree value; |
69 | }; |
70 | |
71 | class copy_prop : public ssa_propagation_engine |
72 | { |
73 | public: |
74 | enum ssa_prop_result visit_stmt (gimple *, edge *, tree *) FINAL OVERRIDE; |
75 | enum ssa_prop_result visit_phi (gphi *) FINAL OVERRIDE; |
76 | }; |
77 | |
78 | static prop_value_t *copy_of; |
79 | static unsigned n_copy_of; |
80 | |
81 | |
82 | /* Return true if this statement may generate a useful copy. */ |
83 | |
84 | static bool |
85 | stmt_may_generate_copy (gimple *stmt) |
86 | { |
87 | if (gimple_code (stmt) == GIMPLE_PHI) |
88 | return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt)); |
89 | |
90 | if (gimple_code (stmt) != GIMPLE_ASSIGN) |
91 | return false; |
92 | |
93 | /* If the statement has volatile operands, it won't generate a |
94 | useful copy. */ |
95 | if (gimple_has_volatile_ops (stmt)) |
96 | return false; |
97 | |
98 | /* Statements with loads and/or stores will never generate a useful copy. */ |
99 | if (gimple_vuse (stmt)) |
100 | return false; |
101 | |
102 | /* Otherwise, the only statements that generate useful copies are |
103 | assignments whose RHS is just an SSA name that doesn't flow |
104 | through abnormal edges. */ |
105 | return ((gimple_assign_rhs_code (stmt) == SSA_NAME |
106 | && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt))) |
107 | || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))); |
108 | } |
109 | |
110 | |
111 | /* Return the copy-of value for VAR. */ |
112 | |
113 | static inline prop_value_t * |
114 | get_copy_of_val (tree var) |
115 | { |
116 | prop_value_t *val = ©_of[SSA_NAME_VERSION (var)]; |
117 | |
118 | if (val->value == NULL_TREE |
119 | && !stmt_may_generate_copy (SSA_NAME_DEF_STMT (var))) |
120 | { |
121 | /* If the variable will never generate a useful copy relation, |
122 | make it its own copy. */ |
123 | val->value = var; |
124 | } |
125 | |
126 | return val; |
127 | } |
128 | |
129 | /* Return the variable VAR is a copy of or VAR if VAR isn't the result |
130 | of a copy. */ |
131 | |
132 | static inline tree |
133 | valueize_val (tree var) |
134 | { |
135 | if (TREE_CODE (var) == SSA_NAME) |
136 | { |
137 | tree val = get_copy_of_val (var)->value; |
138 | if (val) |
139 | return val; |
140 | } |
141 | return var; |
142 | } |
143 | |
144 | /* Set VAL to be the copy of VAR. If that changed return true. */ |
145 | |
146 | static inline bool |
147 | set_copy_of_val (tree var, tree val) |
148 | { |
149 | unsigned int ver = SSA_NAME_VERSION (var); |
150 | tree old; |
151 | |
152 | /* Set FIRST to be the first link in COPY_OF[DEST]. If that |
153 | changed, return true. */ |
154 | old = copy_of[ver].value; |
155 | copy_of[ver].value = val; |
156 | |
157 | if (old != val |
158 | || (val && !operand_equal_p (old, val, 0))) |
159 | return true; |
160 | |
161 | return false; |
162 | } |
163 | |
164 | |
165 | /* Dump the copy-of value for variable VAR to FILE. */ |
166 | |
167 | static void |
168 | dump_copy_of (FILE *file, tree var) |
169 | { |
170 | tree val; |
171 | |
172 | print_generic_expr (file, var, dump_flags); |
173 | if (TREE_CODE (var) != SSA_NAME) |
174 | return; |
175 | |
176 | val = copy_of[SSA_NAME_VERSION (var)].value; |
177 | fprintf (file, " copy-of chain: " ); |
178 | print_generic_expr (file, var); |
179 | fprintf (file, " " ); |
180 | if (!val) |
181 | fprintf (file, "[UNDEFINED]" ); |
182 | else if (val == var) |
183 | fprintf (file, "[NOT A COPY]" ); |
184 | else |
185 | { |
186 | fprintf (file, "-> " ); |
187 | print_generic_expr (file, val); |
188 | fprintf (file, " " ); |
189 | fprintf (file, "[COPY]" ); |
190 | } |
191 | } |
192 | |
193 | |
194 | /* Evaluate the RHS of STMT. If it produces a valid copy, set the LHS |
195 | value and store the LHS into *RESULT_P. */ |
196 | |
197 | static enum ssa_prop_result |
198 | copy_prop_visit_assignment (gimple *stmt, tree *result_p) |
199 | { |
200 | tree lhs, rhs; |
201 | |
202 | lhs = gimple_assign_lhs (stmt); |
203 | rhs = valueize_val (gimple_assign_rhs1 (stmt)); |
204 | |
205 | if (TREE_CODE (lhs) == SSA_NAME) |
206 | { |
207 | /* Straight copy between two SSA names. First, make sure that |
208 | we can propagate the RHS into uses of LHS. */ |
209 | if (!may_propagate_copy (lhs, rhs)) |
210 | return SSA_PROP_VARYING; |
211 | |
212 | *result_p = lhs; |
213 | if (set_copy_of_val (*result_p, rhs)) |
214 | return SSA_PROP_INTERESTING; |
215 | else |
216 | return SSA_PROP_NOT_INTERESTING; |
217 | } |
218 | |
219 | return SSA_PROP_VARYING; |
220 | } |
221 | |
222 | |
223 | /* Visit the GIMPLE_COND STMT. Return SSA_PROP_INTERESTING |
224 | if it can determine which edge will be taken. Otherwise, return |
225 | SSA_PROP_VARYING. */ |
226 | |
227 | static enum ssa_prop_result |
228 | copy_prop_visit_cond_stmt (gimple *stmt, edge *taken_edge_p) |
229 | { |
230 | enum ssa_prop_result retval = SSA_PROP_VARYING; |
231 | location_t loc = gimple_location (stmt); |
232 | |
233 | tree op0 = valueize_val (gimple_cond_lhs (stmt)); |
234 | tree op1 = valueize_val (gimple_cond_rhs (stmt)); |
235 | |
236 | /* See if we can determine the predicate's value. */ |
237 | if (dump_file && (dump_flags & TDF_DETAILS)) |
238 | { |
239 | fprintf (dump_file, "Trying to determine truth value of " ); |
240 | fprintf (dump_file, "predicate " ); |
241 | print_gimple_stmt (dump_file, stmt, 0); |
242 | } |
243 | |
244 | /* Fold COND and see whether we get a useful result. */ |
245 | tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt), |
246 | boolean_type_node, op0, op1); |
247 | if (folded_cond) |
248 | { |
249 | basic_block bb = gimple_bb (stmt); |
250 | *taken_edge_p = find_taken_edge (bb, folded_cond); |
251 | if (*taken_edge_p) |
252 | retval = SSA_PROP_INTERESTING; |
253 | } |
254 | |
255 | if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p) |
256 | fprintf (dump_file, "\nConditional will always take edge %d->%d\n" , |
257 | (*taken_edge_p)->src->index, (*taken_edge_p)->dest->index); |
258 | |
259 | return retval; |
260 | } |
261 | |
262 | |
263 | /* Evaluate statement STMT. If the statement produces a new output |
264 | value, return SSA_PROP_INTERESTING and store the SSA_NAME holding |
265 | the new value in *RESULT_P. |
266 | |
267 | If STMT is a conditional branch and we can determine its truth |
268 | value, set *TAKEN_EDGE_P accordingly. |
269 | |
270 | If the new value produced by STMT is varying, return |
271 | SSA_PROP_VARYING. */ |
272 | |
273 | enum ssa_prop_result |
274 | copy_prop::visit_stmt (gimple *stmt, edge *taken_edge_p, tree *result_p) |
275 | { |
276 | enum ssa_prop_result retval; |
277 | |
278 | if (dump_file && (dump_flags & TDF_DETAILS)) |
279 | { |
280 | fprintf (dump_file, "\nVisiting statement:\n" ); |
281 | print_gimple_stmt (dump_file, stmt, 0, dump_flags); |
282 | fprintf (dump_file, "\n" ); |
283 | } |
284 | |
285 | if (gimple_assign_single_p (stmt) |
286 | && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME |
287 | && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME |
288 | || is_gimple_min_invariant (gimple_assign_rhs1 (stmt)))) |
289 | { |
290 | /* If the statement is a copy assignment, evaluate its RHS to |
291 | see if the lattice value of its output has changed. */ |
292 | retval = copy_prop_visit_assignment (stmt, result_p); |
293 | } |
294 | else if (gimple_code (stmt) == GIMPLE_COND) |
295 | { |
296 | /* See if we can determine which edge goes out of a conditional |
297 | jump. */ |
298 | retval = copy_prop_visit_cond_stmt (stmt, taken_edge_p); |
299 | } |
300 | else |
301 | retval = SSA_PROP_VARYING; |
302 | |
303 | if (retval == SSA_PROP_VARYING) |
304 | { |
305 | tree def; |
306 | ssa_op_iter i; |
307 | |
308 | /* Any other kind of statement is not interesting for constant |
309 | propagation and, therefore, not worth simulating. */ |
310 | if (dump_file && (dump_flags & TDF_DETAILS)) |
311 | fprintf (dump_file, "No interesting values produced.\n" ); |
312 | |
313 | /* The assignment is not a copy operation. Don't visit this |
314 | statement again and mark all the definitions in the statement |
315 | to be copies of nothing. */ |
316 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_ALL_DEFS) |
317 | set_copy_of_val (def, def); |
318 | } |
319 | |
320 | return retval; |
321 | } |
322 | |
323 | |
324 | /* Visit PHI node PHI. If all the arguments produce the same value, |
325 | set it to be the value of the LHS of PHI. */ |
326 | |
327 | enum ssa_prop_result |
328 | copy_prop::visit_phi (gphi *phi) |
329 | { |
330 | enum ssa_prop_result retval; |
331 | unsigned i; |
332 | prop_value_t phi_val = { NULL_TREE }; |
333 | |
334 | tree lhs = gimple_phi_result (phi); |
335 | |
336 | if (dump_file && (dump_flags & TDF_DETAILS)) |
337 | { |
338 | fprintf (dump_file, "\nVisiting PHI node: " ); |
339 | print_gimple_stmt (dump_file, phi, 0, dump_flags); |
340 | } |
341 | |
342 | for (i = 0; i < gimple_phi_num_args (phi); i++) |
343 | { |
344 | prop_value_t *arg_val; |
345 | tree arg_value; |
346 | tree arg = gimple_phi_arg_def (phi, i); |
347 | edge e = gimple_phi_arg_edge (phi, i); |
348 | |
349 | /* We don't care about values flowing through non-executable |
350 | edges. */ |
351 | if (!(e->flags & EDGE_EXECUTABLE)) |
352 | continue; |
353 | |
354 | /* Names that flow through abnormal edges cannot be used to |
355 | derive copies. */ |
356 | if (TREE_CODE (arg) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg)) |
357 | { |
358 | phi_val.value = lhs; |
359 | break; |
360 | } |
361 | |
362 | if (dump_file && (dump_flags & TDF_DETAILS)) |
363 | { |
364 | fprintf (dump_file, "\tArgument #%d: " , i); |
365 | dump_copy_of (dump_file, arg); |
366 | fprintf (dump_file, "\n" ); |
367 | } |
368 | |
369 | if (TREE_CODE (arg) == SSA_NAME) |
370 | { |
371 | arg_val = get_copy_of_val (arg); |
372 | |
373 | /* If we didn't visit the definition of arg yet treat it as |
374 | UNDEFINED. This also handles PHI arguments that are the |
375 | same as lhs. We'll come here again. */ |
376 | if (!arg_val->value) |
377 | continue; |
378 | |
379 | arg_value = arg_val->value; |
380 | } |
381 | else |
382 | arg_value = valueize_val (arg); |
383 | |
384 | /* In loop-closed SSA form do not copy-propagate SSA-names across |
385 | loop exit edges. */ |
386 | if (loops_state_satisfies_p (LOOP_CLOSED_SSA) |
387 | && TREE_CODE (arg_value) == SSA_NAME |
388 | && loop_exit_edge_p (e->src->loop_father, e)) |
389 | { |
390 | phi_val.value = lhs; |
391 | break; |
392 | } |
393 | |
394 | /* If the LHS didn't have a value yet, make it a copy of the |
395 | first argument we find. */ |
396 | if (phi_val.value == NULL_TREE) |
397 | { |
398 | phi_val.value = arg_value; |
399 | continue; |
400 | } |
401 | |
402 | /* If PHI_VAL and ARG don't have a common copy-of chain, then |
403 | this PHI node cannot be a copy operation. */ |
404 | if (phi_val.value != arg_value |
405 | && !operand_equal_p (phi_val.value, arg_value, 0)) |
406 | { |
407 | phi_val.value = lhs; |
408 | break; |
409 | } |
410 | } |
411 | |
412 | if (phi_val.value |
413 | && may_propagate_copy (lhs, phi_val.value) |
414 | && set_copy_of_val (lhs, phi_val.value)) |
415 | retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING; |
416 | else |
417 | retval = SSA_PROP_NOT_INTERESTING; |
418 | |
419 | if (dump_file && (dump_flags & TDF_DETAILS)) |
420 | { |
421 | fprintf (dump_file, "PHI node " ); |
422 | dump_copy_of (dump_file, lhs); |
423 | fprintf (dump_file, "\nTelling the propagator to " ); |
424 | if (retval == SSA_PROP_INTERESTING) |
425 | fprintf (dump_file, "add SSA edges out of this PHI and continue." ); |
426 | else if (retval == SSA_PROP_VARYING) |
427 | fprintf (dump_file, "add SSA edges out of this PHI and never visit again." ); |
428 | else |
429 | fprintf (dump_file, "do nothing with SSA edges and keep iterating." ); |
430 | fprintf (dump_file, "\n\n" ); |
431 | } |
432 | |
433 | return retval; |
434 | } |
435 | |
436 | |
437 | /* Initialize structures used for copy propagation. */ |
438 | |
439 | static void |
440 | init_copy_prop (void) |
441 | { |
442 | basic_block bb; |
443 | |
444 | n_copy_of = num_ssa_names; |
445 | copy_of = XCNEWVEC (prop_value_t, n_copy_of); |
446 | |
447 | FOR_EACH_BB_FN (bb, cfun) |
448 | { |
449 | for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si); |
450 | gsi_next (&si)) |
451 | { |
452 | gimple *stmt = gsi_stmt (si); |
453 | ssa_op_iter iter; |
454 | tree def; |
455 | |
456 | /* The only statements that we care about are those that may |
457 | generate useful copies. We also need to mark conditional |
458 | jumps so that their outgoing edges are added to the work |
459 | lists of the propagator. */ |
460 | if (stmt_ends_bb_p (stmt)) |
461 | prop_set_simulate_again (stmt, true); |
462 | else if (stmt_may_generate_copy (stmt)) |
463 | prop_set_simulate_again (stmt, true); |
464 | else |
465 | prop_set_simulate_again (stmt, false); |
466 | |
467 | /* Mark all the outputs of this statement as not being |
468 | the copy of anything. */ |
469 | FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS) |
470 | if (!prop_simulate_again_p (stmt)) |
471 | set_copy_of_val (def, def); |
472 | } |
473 | |
474 | for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si); |
475 | gsi_next (&si)) |
476 | { |
477 | gphi *phi = si.phi (); |
478 | tree def; |
479 | |
480 | def = gimple_phi_result (phi); |
481 | if (virtual_operand_p (def)) |
482 | prop_set_simulate_again (phi, false); |
483 | else |
484 | prop_set_simulate_again (phi, true); |
485 | |
486 | if (!prop_simulate_again_p (phi)) |
487 | set_copy_of_val (def, def); |
488 | } |
489 | } |
490 | } |
491 | |
492 | class copy_folder : public substitute_and_fold_engine |
493 | { |
494 | public: |
495 | tree get_value (tree) FINAL OVERRIDE; |
496 | }; |
497 | |
498 | /* Callback for substitute_and_fold to get at the final copy-of values. */ |
499 | |
500 | tree |
501 | copy_folder::get_value (tree name) |
502 | { |
503 | tree val; |
504 | if (SSA_NAME_VERSION (name) >= n_copy_of) |
505 | return NULL_TREE; |
506 | val = copy_of[SSA_NAME_VERSION (name)].value; |
507 | if (val && val != name) |
508 | return val; |
509 | return NULL_TREE; |
510 | } |
511 | |
512 | /* Deallocate memory used in copy propagation and do final |
513 | substitution. */ |
514 | |
515 | static bool |
516 | fini_copy_prop (void) |
517 | { |
518 | unsigned i; |
519 | tree var; |
520 | |
521 | /* Set the final copy-of value for each variable by traversing the |
522 | copy-of chains. */ |
523 | FOR_EACH_SSA_NAME (i, var, cfun) |
524 | { |
525 | if (!copy_of[i].value |
526 | || copy_of[i].value == var) |
527 | continue; |
528 | |
529 | /* In theory the points-to solution of all members of the |
530 | copy chain is their intersection. For now we do not bother |
531 | to compute this but only make sure we do not lose points-to |
532 | information completely by setting the points-to solution |
533 | of the representative to the first solution we find if |
534 | it doesn't have one already. */ |
535 | if (copy_of[i].value != var |
536 | && TREE_CODE (copy_of[i].value) == SSA_NAME) |
537 | { |
538 | basic_block copy_of_bb |
539 | = gimple_bb (SSA_NAME_DEF_STMT (copy_of[i].value)); |
540 | basic_block var_bb = gimple_bb (SSA_NAME_DEF_STMT (var)); |
541 | if (POINTER_TYPE_P (TREE_TYPE (var)) |
542 | && SSA_NAME_PTR_INFO (var) |
543 | && !SSA_NAME_PTR_INFO (copy_of[i].value)) |
544 | { |
545 | duplicate_ssa_name_ptr_info (copy_of[i].value, |
546 | SSA_NAME_PTR_INFO (var)); |
547 | /* Points-to information is cfg insensitive, |
548 | but alignment info might be cfg sensitive, if it |
549 | e.g. is derived from VRP derived non-zero bits. |
550 | So, do not copy alignment info if the two SSA_NAMEs |
551 | aren't defined in the same basic block. */ |
552 | if (var_bb != copy_of_bb) |
553 | mark_ptr_info_alignment_unknown |
554 | (SSA_NAME_PTR_INFO (copy_of[i].value)); |
555 | } |
556 | else if (!POINTER_TYPE_P (TREE_TYPE (var)) |
557 | && SSA_NAME_RANGE_INFO (var) |
558 | && !SSA_NAME_RANGE_INFO (copy_of[i].value) |
559 | && var_bb == copy_of_bb) |
560 | duplicate_ssa_name_range_info (copy_of[i].value, |
561 | SSA_NAME_RANGE_TYPE (var), |
562 | SSA_NAME_RANGE_INFO (var)); |
563 | } |
564 | } |
565 | |
566 | class copy_folder copy_folder; |
567 | bool changed = copy_folder.substitute_and_fold (); |
568 | if (changed) |
569 | { |
570 | free_numbers_of_iterations_estimates (cfun); |
571 | if (scev_initialized_p ()) |
572 | scev_reset (); |
573 | } |
574 | |
575 | free (copy_of); |
576 | |
577 | return changed; |
578 | } |
579 | |
580 | |
581 | /* Main entry point to the copy propagator. |
582 | |
583 | PHIS_ONLY is true if we should only consider PHI nodes as generating |
584 | copy propagation opportunities. |
585 | |
586 | The algorithm propagates the value COPY-OF using ssa_propagate. For |
587 | every variable X_i, COPY-OF(X_i) indicates which variable is X_i created |
588 | from. The following example shows how the algorithm proceeds at a |
589 | high level: |
590 | |
591 | 1 a_24 = x_1 |
592 | 2 a_2 = PHI <a_24, x_1> |
593 | 3 a_5 = PHI <a_2> |
594 | 4 x_1 = PHI <x_298, a_5, a_2> |
595 | |
596 | The end result should be that a_2, a_5, a_24 and x_1 are a copy of |
597 | x_298. Propagation proceeds as follows. |
598 | |
599 | Visit #1: a_24 is copy-of x_1. Value changed. |
600 | Visit #2: a_2 is copy-of x_1. Value changed. |
601 | Visit #3: a_5 is copy-of x_1. Value changed. |
602 | Visit #4: x_1 is copy-of x_298. Value changed. |
603 | Visit #1: a_24 is copy-of x_298. Value changed. |
604 | Visit #2: a_2 is copy-of x_298. Value changed. |
605 | Visit #3: a_5 is copy-of x_298. Value changed. |
606 | Visit #4: x_1 is copy-of x_298. Stable state reached. |
607 | |
608 | When visiting PHI nodes, we only consider arguments that flow |
609 | through edges marked executable by the propagation engine. So, |
610 | when visiting statement #2 for the first time, we will only look at |
611 | the first argument (a_24) and optimistically assume that its value |
612 | is the copy of a_24 (x_1). */ |
613 | |
614 | static unsigned int |
615 | execute_copy_prop (void) |
616 | { |
617 | init_copy_prop (); |
618 | class copy_prop copy_prop; |
619 | copy_prop.ssa_propagate (); |
620 | if (fini_copy_prop ()) |
621 | return TODO_cleanup_cfg; |
622 | return 0; |
623 | } |
624 | |
625 | namespace { |
626 | |
627 | const pass_data pass_data_copy_prop = |
628 | { |
629 | GIMPLE_PASS, /* type */ |
630 | "copyprop" , /* name */ |
631 | OPTGROUP_NONE, /* optinfo_flags */ |
632 | TV_TREE_COPY_PROP, /* tv_id */ |
633 | ( PROP_ssa | PROP_cfg ), /* properties_required */ |
634 | 0, /* properties_provided */ |
635 | 0, /* properties_destroyed */ |
636 | 0, /* todo_flags_start */ |
637 | 0, /* todo_flags_finish */ |
638 | }; |
639 | |
640 | class pass_copy_prop : public gimple_opt_pass |
641 | { |
642 | public: |
643 | pass_copy_prop (gcc::context *ctxt) |
644 | : gimple_opt_pass (pass_data_copy_prop, ctxt) |
645 | {} |
646 | |
647 | /* opt_pass methods: */ |
648 | opt_pass * clone () { return new pass_copy_prop (m_ctxt); } |
649 | virtual bool gate (function *) { return flag_tree_copy_prop != 0; } |
650 | virtual unsigned int execute (function *) { return execute_copy_prop (); } |
651 | |
652 | }; // class pass_copy_prop |
653 | |
654 | } // anon namespace |
655 | |
656 | gimple_opt_pass * |
657 | make_pass_copy_prop (gcc::context *ctxt) |
658 | { |
659 | return new pass_copy_prop (ctxt); |
660 | } |
661 | |