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5f718c29 | 1 | /* Routines for discovering and unpropagating edge equivalences. |
2 | Copyright (C) 2005 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 2, 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 COPYING. If not, write to | |
18 | the Free Software Foundation, 59 Temple Place - Suite 330, | |
19 | Boston, MA 02111-1307, USA. */ | |
20 | ||
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "tm.h" | |
25 | #include "tree.h" | |
26 | #include "flags.h" | |
27 | #include "rtl.h" | |
28 | #include "tm_p.h" | |
29 | #include "ggc.h" | |
30 | #include "basic-block.h" | |
31 | #include "output.h" | |
32 | #include "errors.h" | |
33 | #include "expr.h" | |
34 | #include "function.h" | |
35 | #include "diagnostic.h" | |
36 | #include "timevar.h" | |
37 | #include "tree-dump.h" | |
38 | #include "tree-flow.h" | |
39 | #include "domwalk.h" | |
40 | #include "real.h" | |
41 | #include "tree-pass.h" | |
42 | #include "tree-ssa-propagate.h" | |
43 | #include "langhooks.h" | |
44 | ||
45 | /* The basic structure describing an equivalency created by traversing | |
46 | an edge. Traversing the edge effectively means that we can assume | |
47 | that we've seen an assignment LHS = RHS. */ | |
48 | struct edge_equivalency | |
49 | { | |
50 | tree rhs; | |
51 | tree lhs; | |
52 | }; | |
53 | ||
54 | /* This routine finds and records edge equivalences for every edge | |
55 | in the CFG. | |
56 | ||
57 | When complete, each edge that creates an equivalency will have an | |
58 | EDGE_EQUIVALENCY structure hanging off the edge's AUX field. | |
59 | The caller is responsible for freeing the AUX fields. */ | |
60 | ||
61 | static void | |
62 | associate_equivalences_with_edges (void) | |
63 | { | |
64 | basic_block bb; | |
65 | ||
66 | /* Walk over each block. If the block ends with a control statement, | |
67 | then it might create a useful equivalence. */ | |
68 | FOR_EACH_BB (bb) | |
69 | { | |
70 | block_stmt_iterator bsi = bsi_last (bb); | |
71 | tree stmt; | |
72 | ||
73 | /* If the block does not end with a COND_EXPR or SWITCH_EXPR | |
74 | then there is nothing to do. */ | |
75 | if (bsi_end_p (bsi)) | |
76 | continue; | |
77 | ||
78 | stmt = bsi_stmt (bsi); | |
79 | ||
80 | if (!stmt) | |
81 | continue; | |
82 | ||
83 | /* A COND_EXPR may create an equivalency in a variety of different | |
84 | ways. */ | |
85 | if (TREE_CODE (stmt) == COND_EXPR) | |
86 | { | |
87 | tree cond = COND_EXPR_COND (stmt); | |
88 | edge true_edge; | |
89 | edge false_edge; | |
90 | struct edge_equivalency *equivalency; | |
91 | ||
92 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
93 | ||
94 | /* If the conditional is a single variable 'X', record 'X = 1' | |
95 | for the true edge and 'X = 0' on the false edge. */ | |
96 | if (TREE_CODE (cond) == SSA_NAME) | |
97 | { | |
98 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
99 | equivalency->rhs = constant_boolean_node (1, TREE_TYPE (cond)); | |
100 | equivalency->lhs = cond; | |
101 | true_edge->aux = equivalency; | |
102 | ||
103 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
104 | equivalency->rhs = constant_boolean_node (0, TREE_TYPE (cond)); | |
105 | equivalency->lhs = cond; | |
106 | false_edge->aux = equivalency; | |
107 | } | |
108 | /* Equality tests may create one or two equivalences. */ | |
109 | else if (TREE_CODE (cond) == EQ_EXPR || TREE_CODE (cond) == NE_EXPR) | |
110 | { | |
111 | tree op0 = TREE_OPERAND (cond, 0); | |
112 | tree op1 = TREE_OPERAND (cond, 1); | |
113 | ||
114 | /* Special case comparing booleans against a constant as we | |
115 | know the value of OP0 on both arms of the branch. i.e., we | |
116 | can record an equivalence for OP0 rather than COND. */ | |
117 | if (TREE_CODE (op0) == SSA_NAME | |
118 | && TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE | |
119 | && is_gimple_min_invariant (op1)) | |
120 | { | |
121 | if (TREE_CODE (cond) == EQ_EXPR) | |
122 | { | |
123 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
124 | equivalency->lhs = op0; | |
125 | equivalency->rhs = (integer_zerop (op1) | |
126 | ? boolean_false_node | |
127 | : boolean_true_node); | |
128 | true_edge->aux = equivalency; | |
129 | ||
130 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
131 | equivalency->lhs = op0; | |
132 | equivalency->rhs = (integer_zerop (op1) | |
133 | ? boolean_true_node | |
134 | : boolean_false_node); | |
135 | false_edge->aux = equivalency; | |
136 | } | |
137 | else | |
138 | { | |
139 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
140 | equivalency->lhs = op0; | |
141 | equivalency->rhs = (integer_zerop (op1) | |
142 | ? boolean_true_node | |
143 | : boolean_false_node); | |
144 | true_edge->aux = equivalency; | |
145 | ||
146 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
147 | equivalency->lhs = op0; | |
148 | equivalency->rhs = (integer_zerop (op1) | |
149 | ? boolean_false_node | |
150 | : boolean_true_node); | |
151 | false_edge->aux = equivalency; | |
152 | } | |
153 | } | |
154 | ||
155 | if (TREE_CODE (op0) == SSA_NAME | |
156 | && (is_gimple_min_invariant (op1) | |
157 | || TREE_CODE (op1) == SSA_NAME)) | |
158 | { | |
159 | /* For IEEE, -0.0 == 0.0, so we don't necessarily know | |
160 | the sign of a variable compared against zero. If | |
161 | we're honoring signed zeros, then we cannot record | |
162 | this value unless we know that the value is nonzero. */ | |
163 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (op0))) | |
164 | && (TREE_CODE (op1) != REAL_CST | |
165 | || REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (op1)))) | |
166 | continue; | |
167 | ||
168 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
169 | equivalency->lhs = op0; | |
170 | equivalency->rhs = op1; | |
171 | if (TREE_CODE (cond) == EQ_EXPR) | |
172 | true_edge->aux = equivalency; | |
173 | else | |
174 | false_edge->aux = equivalency; | |
175 | ||
176 | } | |
177 | } | |
178 | ||
179 | /* ??? TRUTH_NOT_EXPR can create an equivalence too. */ | |
180 | } | |
181 | ||
182 | /* For a SWITCH_EXPR, a case label which represents a single | |
183 | value and which is the only case label which reaches the | |
184 | target block creates an equivalence. */ | |
185 | if (TREE_CODE (stmt) == SWITCH_EXPR) | |
186 | { | |
187 | tree cond = SWITCH_COND (stmt); | |
188 | ||
189 | if (TREE_CODE (cond) == SSA_NAME) | |
190 | { | |
191 | tree labels = SWITCH_LABELS (stmt); | |
192 | int i, n_labels = TREE_VEC_LENGTH (labels); | |
193 | tree *info = xcalloc (n_basic_blocks, sizeof (tree)); | |
194 | ||
195 | /* Walk over the case label vector. Record blocks | |
196 | which are reached by a single case label which represents | |
197 | a single value. */ | |
198 | for (i = 0; i < n_labels; i++) | |
199 | { | |
200 | tree label = TREE_VEC_ELT (labels, i); | |
201 | basic_block bb = label_to_block (CASE_LABEL (label)); | |
202 | ||
203 | ||
204 | if (CASE_HIGH (label) | |
205 | || !CASE_LOW (label) | |
206 | || info[bb->index]) | |
207 | info[bb->index] = error_mark_node; | |
208 | else | |
209 | info[bb->index] = label; | |
210 | } | |
211 | ||
212 | /* Now walk over the blocks to determine which ones were | |
213 | marked as being reached by a useful case label. */ | |
214 | for (i = 0; i < n_basic_blocks; i++) | |
215 | { | |
216 | tree node = info[i]; | |
217 | ||
218 | if (node != NULL | |
219 | && node != error_mark_node) | |
220 | { | |
221 | tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node)); | |
222 | struct edge_equivalency *equivalency; | |
223 | ||
224 | /* Record an equivalency on the edge from BB to basic | |
225 | block I. */ | |
226 | equivalency = xmalloc (sizeof (struct edge_equivalency)); | |
227 | equivalency->rhs = x; | |
228 | equivalency->lhs = cond; | |
229 | find_edge (bb, BASIC_BLOCK (i))->aux = equivalency; | |
230 | } | |
231 | } | |
232 | free (info); | |
233 | } | |
234 | } | |
235 | ||
236 | } | |
237 | } | |
238 | ||
239 | ||
240 | /* Translating out of SSA sometimes requires inserting copies and | |
241 | constant initializations on edges to eliminate PHI nodes. | |
242 | ||
243 | In some cases those copies and constant initializations are | |
244 | redundant because the target already has the value on the | |
245 | RHS of the assignment. | |
246 | ||
247 | We previously tried to catch these cases after translating | |
248 | out of SSA form. However, that code often missed cases. Worse | |
249 | yet, the cases it missed were also often missed by the RTL | |
250 | optimizers. Thus the resulting code had redundant instructions. | |
251 | ||
252 | This pass attempts to detect these situations before translating | |
253 | out of SSA form. | |
254 | ||
255 | The key concept that this pass is built upon is that these | |
256 | redundant copies and constant initializations often occur | |
257 | due to constant/copy propagating equivalences resulting from | |
258 | COND_EXPRs and SWITCH_EXPRs. | |
259 | ||
260 | We want to do those propagations as they can sometimes allow | |
25f6297d | 261 | the SSA optimizers to do a better job. However, in the cases |
5f718c29 | 262 | where such propagations do not result in further optimization, |
263 | we would like to "undo" the propagation to avoid the redundant | |
264 | copies and constant initializations. | |
265 | ||
266 | This pass works by first associating equivalences with edges in | |
267 | the CFG. For example, the edge leading from a SWITCH_EXPR to | |
268 | its associated CASE_LABEL will have an equivalency between | |
269 | SWITCH_COND and the value in the case label. | |
270 | ||
271 | Once we have found the edge equivalences, we proceed to walk | |
272 | the CFG in dominator order. As we traverse edges we record | |
273 | equivalences associated with those edges we traverse. | |
274 | ||
275 | When we encounter a PHI node, we walk its arguments to see if we | |
276 | have an equivalence for the PHI argument. If so, then we replace | |
277 | the argument. | |
278 | ||
279 | Equivalences are looked up based on their value (think of it as | |
280 | the RHS of an assignment). A value may be an SSA_NAME or an | |
281 | invariant. We may have several SSA_NAMEs with the same value, | |
282 | so with each value we have a list of SSA_NAMEs that have the | |
283 | same value. */ | |
284 | ||
285 | /* As we enter each block we record the value for any edge equivalency | |
286 | leading to this block. If no such edge equivalency exists, then we | |
287 | record NULL. These equivalences are live until we leave the dominator | |
288 | subtree rooted at the block where we record the equivalency. */ | |
1a5e3743 | 289 | static VEC(tree,heap) *equiv_stack; |
5f718c29 | 290 | |
291 | /* Global hash table implementing a mapping from invariant values | |
292 | to a list of SSA_NAMEs which have the same value. We might be | |
293 | able to reuse tree-vn for this code. */ | |
294 | static htab_t equiv; | |
295 | ||
296 | /* Main structure for recording equivalences into our hash table. */ | |
297 | struct equiv_hash_elt | |
298 | { | |
299 | /* The value/key of this entry. */ | |
300 | tree value; | |
301 | ||
302 | /* List of SSA_NAMEs which have the same value/key. */ | |
303 | varray_type equivalences; | |
304 | }; | |
305 | ||
306 | static void uncprop_initialize_block (struct dom_walk_data *, basic_block); | |
307 | static void uncprop_finalize_block (struct dom_walk_data *, basic_block); | |
308 | static void uncprop_into_successor_phis (struct dom_walk_data *, basic_block); | |
309 | ||
310 | /* Hashing and equality routines for the hash table. */ | |
311 | ||
312 | static hashval_t | |
313 | equiv_hash (const void *p) | |
314 | { | |
315 | tree value = ((struct equiv_hash_elt *)p)->value; | |
316 | return iterative_hash_expr (value, 0); | |
317 | } | |
318 | ||
319 | static int | |
320 | equiv_eq (const void *p1, const void *p2) | |
321 | { | |
322 | tree value1 = ((struct equiv_hash_elt *)p1)->value; | |
323 | tree value2 = ((struct equiv_hash_elt *)p2)->value; | |
324 | ||
325 | return operand_equal_p (value1, value2, 0); | |
326 | } | |
327 | ||
328 | /* Remove the most recently recorded equivalency for VALUE. */ | |
329 | ||
330 | static void | |
331 | remove_equivalence (tree value) | |
332 | { | |
333 | struct equiv_hash_elt equiv_hash_elt, *equiv_hash_elt_p; | |
334 | void **slot; | |
335 | ||
336 | equiv_hash_elt.value = value; | |
337 | equiv_hash_elt.equivalences = NULL; | |
338 | ||
339 | slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT); | |
340 | ||
341 | equiv_hash_elt_p = (struct equiv_hash_elt *) *slot; | |
342 | VARRAY_POP (equiv_hash_elt_p->equivalences); | |
343 | } | |
344 | ||
345 | /* Record EQUIVALENCE = VALUE into our hash table. */ | |
346 | ||
347 | static void | |
348 | record_equiv (tree value, tree equivalence) | |
349 | { | |
350 | struct equiv_hash_elt *equiv_hash_elt; | |
351 | void **slot; | |
352 | ||
353 | equiv_hash_elt = xmalloc (sizeof (struct equiv_hash_elt)); | |
354 | equiv_hash_elt->value = value; | |
355 | equiv_hash_elt->equivalences = NULL; | |
356 | ||
357 | slot = htab_find_slot (equiv, equiv_hash_elt, INSERT); | |
358 | ||
359 | if (*slot == NULL) | |
360 | *slot = (void *) equiv_hash_elt; | |
361 | else | |
362 | free (equiv_hash_elt); | |
363 | ||
364 | equiv_hash_elt = (struct equiv_hash_elt *) *slot; | |
365 | ||
366 | if (!equiv_hash_elt->equivalences) | |
367 | VARRAY_TREE_INIT (equiv_hash_elt->equivalences, 10, "value equivs"); | |
368 | VARRAY_PUSH_TREE (equiv_hash_elt->equivalences, equivalence); | |
369 | } | |
370 | ||
371 | /* Main driver for un-cprop. */ | |
372 | ||
373 | static void | |
374 | tree_ssa_uncprop (void) | |
375 | { | |
376 | struct dom_walk_data walk_data; | |
377 | basic_block bb; | |
378 | ||
379 | associate_equivalences_with_edges (); | |
380 | ||
381 | /* Create our global data structures. */ | |
382 | equiv = htab_create (1024, equiv_hash, equiv_eq, free); | |
1a5e3743 | 383 | equiv_stack = VEC_alloc (tree, heap, 2); |
5f718c29 | 384 | |
385 | /* We're going to do a dominator walk, so ensure that we have | |
386 | dominance information. */ | |
387 | calculate_dominance_info (CDI_DOMINATORS); | |
388 | ||
389 | /* Setup callbacks for the generic dominator tree walker. */ | |
390 | walk_data.walk_stmts_backward = false; | |
391 | walk_data.dom_direction = CDI_DOMINATORS; | |
392 | walk_data.initialize_block_local_data = NULL; | |
393 | walk_data.before_dom_children_before_stmts = uncprop_initialize_block; | |
394 | walk_data.before_dom_children_walk_stmts = NULL; | |
395 | walk_data.before_dom_children_after_stmts = uncprop_into_successor_phis; | |
396 | walk_data.after_dom_children_before_stmts = NULL; | |
397 | walk_data.after_dom_children_walk_stmts = NULL; | |
398 | walk_data.after_dom_children_after_stmts = uncprop_finalize_block; | |
399 | walk_data.global_data = NULL; | |
400 | walk_data.block_local_data_size = 0; | |
401 | walk_data.interesting_blocks = NULL; | |
402 | ||
403 | /* Now initialize the dominator walker. */ | |
404 | init_walk_dominator_tree (&walk_data); | |
405 | ||
406 | /* Recursively walk the dominator tree undoing unprofitable | |
407 | constant/copy propagations. */ | |
408 | walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); | |
409 | ||
410 | /* Finalize and clean up. */ | |
411 | fini_walk_dominator_tree (&walk_data); | |
412 | ||
1a5e3743 | 413 | /* EQUIV_STACK should already be empty at this point, so we just |
414 | need to empty elements out of the hash table, free EQUIV_STACK, | |
415 | and cleanup the AUX field on the edges. */ | |
5f718c29 | 416 | htab_delete (equiv); |
1a5e3743 | 417 | VEC_free (tree, heap, equiv_stack); |
5f718c29 | 418 | FOR_EACH_BB (bb) |
419 | { | |
420 | edge e; | |
421 | edge_iterator ei; | |
422 | ||
423 | FOR_EACH_EDGE (e, ei, bb->succs) | |
424 | { | |
425 | if (e->aux) | |
426 | { | |
427 | free (e->aux); | |
428 | e->aux = NULL; | |
429 | } | |
430 | } | |
431 | } | |
432 | ||
433 | } | |
434 | ||
435 | ||
436 | /* We have finished processing the dominator children of BB, perform | |
437 | any finalization actions in preparation for leaving this node in | |
438 | the dominator tree. */ | |
439 | ||
440 | static void | |
441 | uncprop_finalize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
442 | basic_block bb ATTRIBUTE_UNUSED) | |
443 | { | |
5f718c29 | 444 | /* Pop the topmost value off the equiv stack. */ |
1a5e3743 | 445 | tree value = VEC_pop (tree, equiv_stack); |
5f718c29 | 446 | |
447 | /* If that value was non-null, then pop the topmost equivalency off | |
448 | its equivalency stack. */ | |
449 | if (value != NULL) | |
450 | remove_equivalence (value); | |
451 | } | |
452 | ||
453 | /* Unpropagate values from PHI nodes in successor blocks of BB. */ | |
454 | ||
455 | static void | |
456 | uncprop_into_successor_phis (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
457 | basic_block bb) | |
458 | { | |
459 | edge e; | |
460 | edge_iterator ei; | |
461 | ||
462 | /* For each successor edge, first temporarily record any equivalence | |
463 | on that edge. Then unpropagate values in any PHI nodes at the | |
464 | destination of the edge. Then remove the temporary equivalence. */ | |
465 | FOR_EACH_EDGE (e, ei, bb->succs) | |
466 | { | |
467 | tree phi = phi_nodes (e->dest); | |
468 | ||
469 | /* If there are no PHI nodes in this destination, then there is | |
470 | no sense in recording any equivalences. */ | |
471 | if (!phi) | |
472 | continue; | |
473 | ||
474 | /* Record any equivalency associated with E. */ | |
475 | if (e->aux) | |
476 | { | |
477 | struct edge_equivalency *equiv = e->aux; | |
478 | record_equiv (equiv->rhs, equiv->lhs); | |
479 | } | |
480 | ||
481 | /* Walk over the PHI nodes, unpropagating values. */ | |
482 | for ( ; phi; phi = PHI_CHAIN (phi)) | |
483 | { | |
484 | /* Sigh. We'll have more efficient access to this one day. */ | |
485 | tree arg = PHI_ARG_DEF (phi, e->dest_idx); | |
486 | struct equiv_hash_elt equiv_hash_elt; | |
487 | void **slot; | |
488 | ||
489 | /* If the argument is not an invariant, or refers to the same | |
490 | underlying variable as the PHI result, then there's no | |
491 | point in un-propagating the argument. */ | |
492 | if (!is_gimple_min_invariant (arg) | |
493 | && SSA_NAME_VAR (arg) != SSA_NAME_VAR (PHI_RESULT (phi))) | |
494 | continue; | |
495 | ||
496 | /* Lookup this argument's value in the hash table. */ | |
497 | equiv_hash_elt.value = arg; | |
498 | equiv_hash_elt.equivalences = NULL; | |
499 | slot = htab_find_slot (equiv, &equiv_hash_elt, NO_INSERT); | |
500 | ||
501 | if (slot) | |
502 | { | |
503 | struct equiv_hash_elt *elt = *slot; | |
504 | int j; | |
505 | ||
506 | /* Walk every equivalence with the same value. If we find | |
507 | one with the same underlying variable as the PHI result, | |
508 | then replace the value in the argument with its equivalent | |
25f6297d | 509 | SSA_NAME. Use the most recent equivalence as hopefully |
5f718c29 | 510 | that results in shortest lifetimes. */ |
511 | for (j = VARRAY_ACTIVE_SIZE (elt->equivalences) - 1; j >= 0; j--) | |
512 | { | |
513 | tree equiv = VARRAY_TREE (elt->equivalences, j); | |
514 | ||
515 | if (SSA_NAME_VAR (equiv) == SSA_NAME_VAR (PHI_RESULT (phi))) | |
516 | { | |
517 | SET_PHI_ARG_DEF (phi, e->dest_idx, equiv); | |
518 | break; | |
519 | } | |
520 | } | |
521 | } | |
522 | } | |
523 | ||
524 | /* If we had an equivalence associated with this edge, remove it. */ | |
525 | if (e->aux) | |
526 | { | |
527 | struct edge_equivalency *equiv = e->aux; | |
528 | remove_equivalence (equiv->rhs); | |
529 | } | |
530 | } | |
531 | } | |
532 | ||
533 | /* Ignoring loop backedges, if BB has precisely one incoming edge then | |
534 | return that edge. Otherwise return NULL. */ | |
535 | static edge | |
536 | single_incoming_edge_ignoring_loop_edges (basic_block bb) | |
537 | { | |
538 | edge retval = NULL; | |
539 | edge e; | |
540 | edge_iterator ei; | |
541 | ||
542 | FOR_EACH_EDGE (e, ei, bb->preds) | |
543 | { | |
544 | /* A loop back edge can be identified by the destination of | |
545 | the edge dominating the source of the edge. */ | |
546 | if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) | |
547 | continue; | |
548 | ||
549 | /* If we have already seen a non-loop edge, then we must have | |
550 | multiple incoming non-loop edges and thus we return NULL. */ | |
551 | if (retval) | |
552 | return NULL; | |
553 | ||
554 | /* This is the first non-loop incoming edge we have found. Record | |
555 | it. */ | |
556 | retval = e; | |
557 | } | |
558 | ||
559 | return retval; | |
560 | } | |
561 | ||
562 | static void | |
563 | uncprop_initialize_block (struct dom_walk_data *walk_data ATTRIBUTE_UNUSED, | |
564 | basic_block bb) | |
565 | { | |
566 | basic_block parent; | |
567 | edge e; | |
568 | bool recorded = false; | |
569 | ||
570 | /* If this block is dominated by a single incoming edge and that edge | |
571 | has an equivalency, then record the equivalency and push the | |
572 | VALUE onto EQUIV_STACK. Else push a NULL entry on EQUIV_STACK. */ | |
573 | parent = get_immediate_dominator (CDI_DOMINATORS, bb); | |
574 | if (parent) | |
575 | { | |
576 | e = single_incoming_edge_ignoring_loop_edges (bb); | |
577 | ||
578 | if (e && e->src == parent && e->aux) | |
579 | { | |
580 | struct edge_equivalency *equiv = e->aux; | |
581 | ||
582 | record_equiv (equiv->rhs, equiv->lhs); | |
1a5e3743 | 583 | VEC_safe_push (tree, heap, equiv_stack, equiv->rhs); |
5f718c29 | 584 | recorded = true; |
585 | } | |
586 | } | |
587 | ||
588 | if (!recorded) | |
1a5e3743 | 589 | VEC_safe_push (tree, heap, equiv_stack, NULL_TREE); |
5f718c29 | 590 | } |
591 | ||
592 | static bool | |
593 | gate_uncprop (void) | |
594 | { | |
595 | return flag_tree_dom != 0; | |
596 | } | |
597 | ||
598 | struct tree_opt_pass pass_uncprop = | |
599 | { | |
600 | "uncprop", /* name */ | |
601 | gate_uncprop, /* gate */ | |
602 | tree_ssa_uncprop, /* execute */ | |
603 | NULL, /* sub */ | |
604 | NULL, /* next */ | |
605 | 0, /* static_pass_number */ | |
606 | TV_TREE_SSA_UNCPROP, /* tv_id */ | |
607 | PROP_cfg | PROP_ssa, /* properties_required */ | |
608 | 0, /* properties_provided */ | |
609 | 0, /* properties_destroyed */ | |
610 | 0, /* todo_flags_start */ | |
611 | TODO_dump_func | TODO_verify_ssa, /* todo_flags_finish */ | |
612 | 0 /* letter */ | |
613 | }; |