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5f718c29 | 1 | /* Routines for discovering and unpropagating edge equivalences. |
d353bf18 | 2 | Copyright (C) 2005-2015 Free Software Foundation, Inc. |
5f718c29 | 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 | |
8c4c00c1 | 8 | the Free Software Foundation; either version 3, or (at your option) |
5f718c29 | 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 | |
8c4c00c1 | 17 | along with GCC; see the file COPYING3. If not see |
18 | <http://www.gnu.org/licenses/>. */ | |
5f718c29 | 19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
b20a8bb4 | 24 | #include "alias.h" |
25 | #include "symtab.h" | |
5f718c29 | 26 | #include "tree.h" |
b20a8bb4 | 27 | #include "fold-const.h" |
9ed99284 | 28 | #include "stor-layout.h" |
5f718c29 | 29 | #include "flags.h" |
5f718c29 | 30 | #include "tm_p.h" |
94ea8568 | 31 | #include "predict.h" |
a3020f2f | 32 | #include "hard-reg-set.h" |
5f718c29 | 33 | #include "function.h" |
94ea8568 | 34 | #include "dominance.h" |
35 | #include "cfg.h" | |
36 | #include "cfganal.h" | |
37 | #include "basic-block.h" | |
bc61cadb | 38 | #include "tree-ssa-alias.h" |
39 | #include "internal-fn.h" | |
40 | #include "gimple-expr.h" | |
073c1fd5 | 41 | #include "gimple.h" |
dcf1a1ec | 42 | #include "gimple-iterator.h" |
073c1fd5 | 43 | #include "gimple-ssa.h" |
44 | #include "tree-cfg.h" | |
45 | #include "tree-phinodes.h" | |
46 | #include "ssa-iterators.h" | |
5f718c29 | 47 | #include "domwalk.h" |
5f718c29 | 48 | #include "tree-pass.h" |
49 | #include "tree-ssa-propagate.h" | |
5f718c29 | 50 | |
51 | /* The basic structure describing an equivalency created by traversing | |
52 | an edge. Traversing the edge effectively means that we can assume | |
53 | that we've seen an assignment LHS = RHS. */ | |
54 | struct edge_equivalency | |
55 | { | |
56 | tree rhs; | |
57 | tree lhs; | |
58 | }; | |
59 | ||
60 | /* This routine finds and records edge equivalences for every edge | |
61 | in the CFG. | |
62 | ||
63 | When complete, each edge that creates an equivalency will have an | |
48e1416a | 64 | EDGE_EQUIVALENCY structure hanging off the edge's AUX field. |
5f718c29 | 65 | The caller is responsible for freeing the AUX fields. */ |
66 | ||
67 | static void | |
68 | associate_equivalences_with_edges (void) | |
69 | { | |
70 | basic_block bb; | |
71 | ||
72 | /* Walk over each block. If the block ends with a control statement, | |
73 | then it might create a useful equivalence. */ | |
fc00614f | 74 | FOR_EACH_BB_FN (bb, cfun) |
5f718c29 | 75 | { |
75a70cf9 | 76 | gimple_stmt_iterator gsi = gsi_last_bb (bb); |
77 | gimple stmt; | |
5f718c29 | 78 | |
79 | /* If the block does not end with a COND_EXPR or SWITCH_EXPR | |
80 | then there is nothing to do. */ | |
75a70cf9 | 81 | if (gsi_end_p (gsi)) |
5f718c29 | 82 | continue; |
83 | ||
75a70cf9 | 84 | stmt = gsi_stmt (gsi); |
5f718c29 | 85 | |
86 | if (!stmt) | |
87 | continue; | |
88 | ||
89 | /* A COND_EXPR may create an equivalency in a variety of different | |
90 | ways. */ | |
75a70cf9 | 91 | if (gimple_code (stmt) == GIMPLE_COND) |
5f718c29 | 92 | { |
5f718c29 | 93 | edge true_edge; |
94 | edge false_edge; | |
95 | struct edge_equivalency *equivalency; | |
75a70cf9 | 96 | enum tree_code code = gimple_cond_code (stmt); |
5f718c29 | 97 | |
98 | extract_true_false_edges_from_block (bb, &true_edge, &false_edge); | |
99 | ||
5f718c29 | 100 | /* Equality tests may create one or two equivalences. */ |
75a70cf9 | 101 | if (code == EQ_EXPR || code == NE_EXPR) |
5f718c29 | 102 | { |
75a70cf9 | 103 | tree op0 = gimple_cond_lhs (stmt); |
104 | tree op1 = gimple_cond_rhs (stmt); | |
5f718c29 | 105 | |
106 | /* Special case comparing booleans against a constant as we | |
107 | know the value of OP0 on both arms of the branch. i.e., we | |
108 | can record an equivalence for OP0 rather than COND. */ | |
109 | if (TREE_CODE (op0) == SSA_NAME | |
932540b6 | 110 | && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0) |
5f718c29 | 111 | && TREE_CODE (TREE_TYPE (op0)) == BOOLEAN_TYPE |
112 | && is_gimple_min_invariant (op1)) | |
113 | { | |
75a70cf9 | 114 | if (code == EQ_EXPR) |
5f718c29 | 115 | { |
945865c5 | 116 | equivalency = XNEW (struct edge_equivalency); |
5f718c29 | 117 | equivalency->lhs = op0; |
118 | equivalency->rhs = (integer_zerop (op1) | |
119 | ? boolean_false_node | |
120 | : boolean_true_node); | |
121 | true_edge->aux = equivalency; | |
122 | ||
945865c5 | 123 | equivalency = XNEW (struct edge_equivalency); |
5f718c29 | 124 | equivalency->lhs = op0; |
125 | equivalency->rhs = (integer_zerop (op1) | |
126 | ? boolean_true_node | |
127 | : boolean_false_node); | |
128 | false_edge->aux = equivalency; | |
129 | } | |
130 | else | |
131 | { | |
945865c5 | 132 | equivalency = XNEW (struct edge_equivalency); |
5f718c29 | 133 | equivalency->lhs = op0; |
134 | equivalency->rhs = (integer_zerop (op1) | |
135 | ? boolean_true_node | |
136 | : boolean_false_node); | |
137 | true_edge->aux = equivalency; | |
138 | ||
945865c5 | 139 | equivalency = XNEW (struct edge_equivalency); |
5f718c29 | 140 | equivalency->lhs = op0; |
141 | equivalency->rhs = (integer_zerop (op1) | |
142 | ? boolean_false_node | |
143 | : boolean_true_node); | |
144 | false_edge->aux = equivalency; | |
145 | } | |
146 | } | |
147 | ||
024e445d | 148 | else if (TREE_CODE (op0) == SSA_NAME |
149 | && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op0) | |
150 | && (is_gimple_min_invariant (op1) | |
151 | || (TREE_CODE (op1) == SSA_NAME | |
152 | && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op1)))) | |
5f718c29 | 153 | { |
154 | /* For IEEE, -0.0 == 0.0, so we don't necessarily know | |
155 | the sign of a variable compared against zero. If | |
156 | we're honoring signed zeros, then we cannot record | |
157 | this value unless we know that the value is nonzero. */ | |
fe994837 | 158 | if (HONOR_SIGNED_ZEROS (op0) |
5f718c29 | 159 | && (TREE_CODE (op1) != REAL_CST |
160 | || REAL_VALUES_EQUAL (dconst0, TREE_REAL_CST (op1)))) | |
161 | continue; | |
162 | ||
945865c5 | 163 | equivalency = XNEW (struct edge_equivalency); |
5f718c29 | 164 | equivalency->lhs = op0; |
165 | equivalency->rhs = op1; | |
75a70cf9 | 166 | if (code == EQ_EXPR) |
5f718c29 | 167 | true_edge->aux = equivalency; |
48e1416a | 168 | else |
5f718c29 | 169 | false_edge->aux = equivalency; |
170 | ||
171 | } | |
172 | } | |
173 | ||
174 | /* ??? TRUTH_NOT_EXPR can create an equivalence too. */ | |
175 | } | |
176 | ||
177 | /* For a SWITCH_EXPR, a case label which represents a single | |
178 | value and which is the only case label which reaches the | |
179 | target block creates an equivalence. */ | |
75a70cf9 | 180 | else if (gimple_code (stmt) == GIMPLE_SWITCH) |
5f718c29 | 181 | { |
1a91d914 | 182 | gswitch *switch_stmt = as_a <gswitch *> (stmt); |
183 | tree cond = gimple_switch_index (switch_stmt); | |
5f718c29 | 184 | |
932540b6 | 185 | if (TREE_CODE (cond) == SSA_NAME |
186 | && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (cond)) | |
5f718c29 | 187 | { |
1a91d914 | 188 | int i, n_labels = gimple_switch_num_labels (switch_stmt); |
fe672ac0 | 189 | tree *info = XCNEWVEC (tree, last_basic_block_for_fn (cfun)); |
5f718c29 | 190 | |
191 | /* Walk over the case label vector. Record blocks | |
192 | which are reached by a single case label which represents | |
193 | a single value. */ | |
194 | for (i = 0; i < n_labels; i++) | |
195 | { | |
1a91d914 | 196 | tree label = gimple_switch_label (switch_stmt, i); |
5f718c29 | 197 | basic_block bb = label_to_block (CASE_LABEL (label)); |
198 | ||
5f718c29 | 199 | if (CASE_HIGH (label) |
200 | || !CASE_LOW (label) | |
201 | || info[bb->index]) | |
202 | info[bb->index] = error_mark_node; | |
203 | else | |
204 | info[bb->index] = label; | |
205 | } | |
206 | ||
207 | /* Now walk over the blocks to determine which ones were | |
208 | marked as being reached by a useful case label. */ | |
a28770e1 | 209 | for (i = 0; i < n_basic_blocks_for_fn (cfun); i++) |
5f718c29 | 210 | { |
211 | tree node = info[i]; | |
212 | ||
213 | if (node != NULL | |
214 | && node != error_mark_node) | |
215 | { | |
216 | tree x = fold_convert (TREE_TYPE (cond), CASE_LOW (node)); | |
217 | struct edge_equivalency *equivalency; | |
218 | ||
219 | /* Record an equivalency on the edge from BB to basic | |
220 | block I. */ | |
945865c5 | 221 | equivalency = XNEW (struct edge_equivalency); |
5f718c29 | 222 | equivalency->rhs = x; |
223 | equivalency->lhs = cond; | |
f5a6b05f | 224 | find_edge (bb, BASIC_BLOCK_FOR_FN (cfun, i))->aux = |
225 | equivalency; | |
5f718c29 | 226 | } |
227 | } | |
228 | free (info); | |
229 | } | |
230 | } | |
231 | ||
232 | } | |
233 | } | |
234 | ||
235 | ||
236 | /* Translating out of SSA sometimes requires inserting copies and | |
237 | constant initializations on edges to eliminate PHI nodes. | |
238 | ||
239 | In some cases those copies and constant initializations are | |
240 | redundant because the target already has the value on the | |
241 | RHS of the assignment. | |
242 | ||
243 | We previously tried to catch these cases after translating | |
244 | out of SSA form. However, that code often missed cases. Worse | |
245 | yet, the cases it missed were also often missed by the RTL | |
246 | optimizers. Thus the resulting code had redundant instructions. | |
247 | ||
248 | This pass attempts to detect these situations before translating | |
249 | out of SSA form. | |
250 | ||
251 | The key concept that this pass is built upon is that these | |
252 | redundant copies and constant initializations often occur | |
253 | due to constant/copy propagating equivalences resulting from | |
254 | COND_EXPRs and SWITCH_EXPRs. | |
255 | ||
256 | We want to do those propagations as they can sometimes allow | |
25f6297d | 257 | the SSA optimizers to do a better job. However, in the cases |
5f718c29 | 258 | where such propagations do not result in further optimization, |
259 | we would like to "undo" the propagation to avoid the redundant | |
260 | copies and constant initializations. | |
261 | ||
262 | This pass works by first associating equivalences with edges in | |
263 | the CFG. For example, the edge leading from a SWITCH_EXPR to | |
264 | its associated CASE_LABEL will have an equivalency between | |
265 | SWITCH_COND and the value in the case label. | |
266 | ||
267 | Once we have found the edge equivalences, we proceed to walk | |
268 | the CFG in dominator order. As we traverse edges we record | |
269 | equivalences associated with those edges we traverse. | |
270 | ||
271 | When we encounter a PHI node, we walk its arguments to see if we | |
272 | have an equivalence for the PHI argument. If so, then we replace | |
273 | the argument. | |
274 | ||
275 | Equivalences are looked up based on their value (think of it as | |
276 | the RHS of an assignment). A value may be an SSA_NAME or an | |
277 | invariant. We may have several SSA_NAMEs with the same value, | |
278 | so with each value we have a list of SSA_NAMEs that have the | |
279 | same value. */ | |
280 | ||
5f718c29 | 281 | |
5f718c29 | 282 | /* Main structure for recording equivalences into our hash table. */ |
283 | struct equiv_hash_elt | |
284 | { | |
285 | /* The value/key of this entry. */ | |
286 | tree value; | |
287 | ||
288 | /* List of SSA_NAMEs which have the same value/key. */ | |
f1f41a6c | 289 | vec<tree> equivalences; |
5f718c29 | 290 | }; |
291 | ||
d9dd21a8 | 292 | /* Value to ssa name equivalence hashtable helpers. */ |
5f718c29 | 293 | |
d62dd039 | 294 | struct val_ssa_equiv_hash_traits : default_hashmap_traits |
d9dd21a8 | 295 | { |
d62dd039 | 296 | static inline hashval_t hash (tree); |
297 | static inline bool equal_keys (tree, tree); | |
298 | template<typename T> static inline void remove (T &); | |
d9dd21a8 | 299 | }; |
5f718c29 | 300 | |
d9dd21a8 | 301 | inline hashval_t |
d62dd039 | 302 | val_ssa_equiv_hash_traits::hash (tree value) |
5f718c29 | 303 | { |
5f718c29 | 304 | return iterative_hash_expr (value, 0); |
305 | } | |
306 | ||
d9dd21a8 | 307 | inline bool |
d62dd039 | 308 | val_ssa_equiv_hash_traits::equal_keys (tree value1, tree value2) |
5f718c29 | 309 | { |
5f718c29 | 310 | return operand_equal_p (value1, value2, 0); |
311 | } | |
312 | ||
96a7ab57 | 313 | /* Free an instance of equiv_hash_elt. */ |
314 | ||
d62dd039 | 315 | template<typename T> |
d9dd21a8 | 316 | inline void |
d62dd039 | 317 | val_ssa_equiv_hash_traits::remove (T &elt) |
96a7ab57 | 318 | { |
d62dd039 | 319 | elt.m_value.release (); |
96a7ab57 | 320 | } |
321 | ||
d9dd21a8 | 322 | /* Global hash table implementing a mapping from invariant values |
323 | to a list of SSA_NAMEs which have the same value. We might be | |
324 | able to reuse tree-vn for this code. */ | |
d62dd039 | 325 | static hash_map<tree, vec<tree>, val_ssa_equiv_hash_traits> *val_ssa_equiv; |
d9dd21a8 | 326 | |
d9dd21a8 | 327 | static void uncprop_into_successor_phis (basic_block); |
328 | ||
5f718c29 | 329 | /* Remove the most recently recorded equivalency for VALUE. */ |
330 | ||
331 | static void | |
332 | remove_equivalence (tree value) | |
333 | { | |
d62dd039 | 334 | val_ssa_equiv->get (value)->pop (); |
5f718c29 | 335 | } |
336 | ||
337 | /* Record EQUIVALENCE = VALUE into our hash table. */ | |
338 | ||
339 | static void | |
340 | record_equiv (tree value, tree equivalence) | |
341 | { | |
d62dd039 | 342 | val_ssa_equiv->get_or_insert (value).safe_push (equivalence); |
5f718c29 | 343 | } |
344 | ||
54c91640 | 345 | class uncprop_dom_walker : public dom_walker |
346 | { | |
347 | public: | |
e85cf4e5 | 348 | uncprop_dom_walker (cdi_direction direction) : dom_walker (direction) {} |
54c91640 | 349 | |
350 | virtual void before_dom_children (basic_block); | |
351 | virtual void after_dom_children (basic_block); | |
352 | ||
353 | private: | |
354 | ||
ae84f584 | 355 | /* As we enter each block we record the value for any edge equivalency |
356 | leading to this block. If no such edge equivalency exists, then we | |
357 | record NULL. These equivalences are live until we leave the dominator | |
358 | subtree rooted at the block where we record the equivalency. */ | |
4997014d | 359 | auto_vec<tree, 2> m_equiv_stack; |
54c91640 | 360 | }; |
361 | ||
5f718c29 | 362 | /* We have finished processing the dominator children of BB, perform |
363 | any finalization actions in preparation for leaving this node in | |
364 | the dominator tree. */ | |
365 | ||
54c91640 | 366 | void |
367 | uncprop_dom_walker::after_dom_children (basic_block bb ATTRIBUTE_UNUSED) | |
5f718c29 | 368 | { |
5f718c29 | 369 | /* Pop the topmost value off the equiv stack. */ |
ae84f584 | 370 | tree value = m_equiv_stack.pop (); |
5f718c29 | 371 | |
372 | /* If that value was non-null, then pop the topmost equivalency off | |
373 | its equivalency stack. */ | |
374 | if (value != NULL) | |
375 | remove_equivalence (value); | |
376 | } | |
377 | ||
378 | /* Unpropagate values from PHI nodes in successor blocks of BB. */ | |
379 | ||
380 | static void | |
6bf320fb | 381 | uncprop_into_successor_phis (basic_block bb) |
5f718c29 | 382 | { |
383 | edge e; | |
384 | edge_iterator ei; | |
385 | ||
386 | /* For each successor edge, first temporarily record any equivalence | |
387 | on that edge. Then unpropagate values in any PHI nodes at the | |
388 | destination of the edge. Then remove the temporary equivalence. */ | |
389 | FOR_EACH_EDGE (e, ei, bb->succs) | |
390 | { | |
75a70cf9 | 391 | gimple_seq phis = phi_nodes (e->dest); |
392 | gimple_stmt_iterator gsi; | |
5f718c29 | 393 | |
394 | /* If there are no PHI nodes in this destination, then there is | |
395 | no sense in recording any equivalences. */ | |
be2517f5 | 396 | if (gimple_seq_empty_p (phis)) |
5f718c29 | 397 | continue; |
398 | ||
399 | /* Record any equivalency associated with E. */ | |
400 | if (e->aux) | |
401 | { | |
945865c5 | 402 | struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux; |
5f718c29 | 403 | record_equiv (equiv->rhs, equiv->lhs); |
404 | } | |
405 | ||
406 | /* Walk over the PHI nodes, unpropagating values. */ | |
75a70cf9 | 407 | for (gsi = gsi_start (phis) ; !gsi_end_p (gsi); gsi_next (&gsi)) |
5f718c29 | 408 | { |
75a70cf9 | 409 | gimple phi = gsi_stmt (gsi); |
5f718c29 | 410 | tree arg = PHI_ARG_DEF (phi, e->dest_idx); |
ec11736b | 411 | tree res = PHI_RESULT (phi); |
5f718c29 | 412 | |
f82f0ea5 | 413 | /* If the argument is not an invariant and can be potentially |
414 | coalesced with the result, then there's no point in | |
415 | un-propagating the argument. */ | |
5f718c29 | 416 | if (!is_gimple_min_invariant (arg) |
f82f0ea5 | 417 | && gimple_can_coalesce_p (arg, res)) |
5f718c29 | 418 | continue; |
419 | ||
420 | /* Lookup this argument's value in the hash table. */ | |
d62dd039 | 421 | vec<tree> *equivalences = val_ssa_equiv->get (arg); |
422 | if (equivalences) | |
5f718c29 | 423 | { |
5f718c29 | 424 | /* Walk every equivalence with the same value. If we find |
f82f0ea5 | 425 | one that can potentially coalesce with the PHI rsult, |
5f718c29 | 426 | then replace the value in the argument with its equivalent |
25f6297d | 427 | SSA_NAME. Use the most recent equivalence as hopefully |
5f718c29 | 428 | that results in shortest lifetimes. */ |
d62dd039 | 429 | for (int j = equivalences->length () - 1; j >= 0; j--) |
5f718c29 | 430 | { |
d62dd039 | 431 | tree equiv = (*equivalences)[j]; |
5f718c29 | 432 | |
f82f0ea5 | 433 | if (gimple_can_coalesce_p (equiv, res)) |
5f718c29 | 434 | { |
435 | SET_PHI_ARG_DEF (phi, e->dest_idx, equiv); | |
436 | break; | |
437 | } | |
438 | } | |
439 | } | |
440 | } | |
441 | ||
442 | /* If we had an equivalence associated with this edge, remove it. */ | |
443 | if (e->aux) | |
444 | { | |
945865c5 | 445 | struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux; |
5f718c29 | 446 | remove_equivalence (equiv->rhs); |
447 | } | |
448 | } | |
449 | } | |
450 | ||
451 | /* Ignoring loop backedges, if BB has precisely one incoming edge then | |
452 | return that edge. Otherwise return NULL. */ | |
453 | static edge | |
454 | single_incoming_edge_ignoring_loop_edges (basic_block bb) | |
455 | { | |
456 | edge retval = NULL; | |
457 | edge e; | |
458 | edge_iterator ei; | |
459 | ||
460 | FOR_EACH_EDGE (e, ei, bb->preds) | |
461 | { | |
462 | /* A loop back edge can be identified by the destination of | |
463 | the edge dominating the source of the edge. */ | |
464 | if (dominated_by_p (CDI_DOMINATORS, e->src, e->dest)) | |
465 | continue; | |
466 | ||
467 | /* If we have already seen a non-loop edge, then we must have | |
468 | multiple incoming non-loop edges and thus we return NULL. */ | |
469 | if (retval) | |
470 | return NULL; | |
471 | ||
472 | /* This is the first non-loop incoming edge we have found. Record | |
473 | it. */ | |
474 | retval = e; | |
475 | } | |
476 | ||
477 | return retval; | |
478 | } | |
479 | ||
54c91640 | 480 | void |
481 | uncprop_dom_walker::before_dom_children (basic_block bb) | |
5f718c29 | 482 | { |
483 | basic_block parent; | |
484 | edge e; | |
485 | bool recorded = false; | |
486 | ||
487 | /* If this block is dominated by a single incoming edge and that edge | |
488 | has an equivalency, then record the equivalency and push the | |
489 | VALUE onto EQUIV_STACK. Else push a NULL entry on EQUIV_STACK. */ | |
490 | parent = get_immediate_dominator (CDI_DOMINATORS, bb); | |
491 | if (parent) | |
492 | { | |
493 | e = single_incoming_edge_ignoring_loop_edges (bb); | |
494 | ||
495 | if (e && e->src == parent && e->aux) | |
496 | { | |
945865c5 | 497 | struct edge_equivalency *equiv = (struct edge_equivalency *) e->aux; |
5f718c29 | 498 | |
499 | record_equiv (equiv->rhs, equiv->lhs); | |
ae84f584 | 500 | m_equiv_stack.safe_push (equiv->rhs); |
5f718c29 | 501 | recorded = true; |
502 | } | |
503 | } | |
504 | ||
505 | if (!recorded) | |
ae84f584 | 506 | m_equiv_stack.safe_push (NULL_TREE); |
6bf320fb | 507 | |
508 | uncprop_into_successor_phis (bb); | |
5f718c29 | 509 | } |
510 | ||
cbe8bda8 | 511 | namespace { |
512 | ||
513 | const pass_data pass_data_uncprop = | |
5f718c29 | 514 | { |
cbe8bda8 | 515 | GIMPLE_PASS, /* type */ |
516 | "uncprop", /* name */ | |
517 | OPTGROUP_NONE, /* optinfo_flags */ | |
cbe8bda8 | 518 | TV_TREE_SSA_UNCPROP, /* tv_id */ |
519 | ( PROP_cfg | PROP_ssa ), /* properties_required */ | |
520 | 0, /* properties_provided */ | |
521 | 0, /* properties_destroyed */ | |
522 | 0, /* todo_flags_start */ | |
8b88439e | 523 | 0, /* todo_flags_finish */ |
5f718c29 | 524 | }; |
cbe8bda8 | 525 | |
526 | class pass_uncprop : public gimple_opt_pass | |
527 | { | |
528 | public: | |
9af5ce0c | 529 | pass_uncprop (gcc::context *ctxt) |
530 | : gimple_opt_pass (pass_data_uncprop, ctxt) | |
cbe8bda8 | 531 | {} |
532 | ||
533 | /* opt_pass methods: */ | |
ae84f584 | 534 | opt_pass * clone () { return new pass_uncprop (m_ctxt); } |
31315c24 | 535 | virtual bool gate (function *) { return flag_tree_dom != 0; } |
65b0537f | 536 | virtual unsigned int execute (function *); |
cbe8bda8 | 537 | |
538 | }; // class pass_uncprop | |
539 | ||
65b0537f | 540 | unsigned int |
541 | pass_uncprop::execute (function *fun) | |
542 | { | |
543 | basic_block bb; | |
544 | ||
545 | associate_equivalences_with_edges (); | |
546 | ||
547 | /* Create our global data structures. */ | |
d62dd039 | 548 | val_ssa_equiv |
549 | = new hash_map<tree, vec<tree>, val_ssa_equiv_hash_traits> (1024); | |
65b0537f | 550 | |
551 | /* We're going to do a dominator walk, so ensure that we have | |
552 | dominance information. */ | |
553 | calculate_dominance_info (CDI_DOMINATORS); | |
554 | ||
555 | /* Recursively walk the dominator tree undoing unprofitable | |
556 | constant/copy propagations. */ | |
557 | uncprop_dom_walker (CDI_DOMINATORS).walk (fun->cfg->x_entry_block_ptr); | |
558 | ||
559 | /* we just need to empty elements out of the hash table, and cleanup the | |
560 | AUX field on the edges. */ | |
c1f445d2 | 561 | delete val_ssa_equiv; |
562 | val_ssa_equiv = NULL; | |
65b0537f | 563 | FOR_EACH_BB_FN (bb, fun) |
564 | { | |
565 | edge e; | |
566 | edge_iterator ei; | |
567 | ||
568 | FOR_EACH_EDGE (e, ei, bb->succs) | |
569 | { | |
570 | if (e->aux) | |
571 | { | |
572 | free (e->aux); | |
573 | e->aux = NULL; | |
574 | } | |
575 | } | |
576 | } | |
577 | return 0; | |
578 | } | |
579 | ||
cbe8bda8 | 580 | } // anon namespace |
581 | ||
582 | gimple_opt_pass * | |
583 | make_pass_uncprop (gcc::context *ctxt) | |
584 | { | |
585 | return new pass_uncprop (ctxt); | |
586 | } |