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4ee9c684 | 1 | /* Optimization of PHI nodes by converting them into straightline code. |
41076ef6 | 2 | Copyright (C) 2004, 2005, 2006, 2007 Free Software Foundation, Inc. |
4ee9c684 | 3 | |
4 | This file is part of GCC. | |
20e5647c | 5 | |
4ee9c684 | 6 | GCC is free software; you can redistribute it and/or modify it |
7 | under the terms of the GNU General Public License as published by the | |
8c4c00c1 | 8 | Free Software Foundation; either version 3, or (at your option) any |
4ee9c684 | 9 | later version. |
20e5647c | 10 | |
4ee9c684 | 11 | GCC is distributed in the hope that it will be useful, but WITHOUT |
12 | ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
13 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
14 | for more details. | |
20e5647c | 15 | |
4ee9c684 | 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/>. */ | |
4ee9c684 | 19 | |
20 | #include "config.h" | |
21 | #include "system.h" | |
22 | #include "coretypes.h" | |
23 | #include "tm.h" | |
4ee9c684 | 24 | #include "ggc.h" |
25 | #include "tree.h" | |
26 | #include "rtl.h" | |
0beac6fc | 27 | #include "flags.h" |
4ee9c684 | 28 | #include "tm_p.h" |
29 | #include "basic-block.h" | |
30 | #include "timevar.h" | |
31 | #include "diagnostic.h" | |
32 | #include "tree-flow.h" | |
33 | #include "tree-pass.h" | |
34 | #include "tree-dump.h" | |
35 | #include "langhooks.h" | |
e6d0e152 | 36 | #include "pointer-set.h" |
37 | #include "domwalk.h" | |
4ee9c684 | 38 | |
e6d0e152 | 39 | static unsigned int tree_ssa_phiopt_worker (bool); |
a4844041 | 40 | static bool conditional_replacement (basic_block, basic_block, |
33784d89 | 41 | edge, edge, tree, tree, tree); |
a4844041 | 42 | static bool value_replacement (basic_block, basic_block, |
33784d89 | 43 | edge, edge, tree, tree, tree); |
a4844041 | 44 | static bool minmax_replacement (basic_block, basic_block, |
194899bf | 45 | edge, edge, tree, tree, tree); |
a4844041 | 46 | static bool abs_replacement (basic_block, basic_block, |
33784d89 | 47 | edge, edge, tree, tree, tree); |
e6d0e152 | 48 | static bool cond_store_replacement (basic_block, basic_block, edge, edge, |
49 | struct pointer_set_t *); | |
50 | static struct pointer_set_t * get_non_trapping (void); | |
a4844041 | 51 | static void replace_phi_edge_with_variable (basic_block, edge, tree, tree); |
902929aa | 52 | |
caac37c2 | 53 | /* This pass tries to replaces an if-then-else block with an |
54 | assignment. We have four kinds of transformations. Some of these | |
55 | transformations are also performed by the ifcvt RTL optimizer. | |
56 | ||
57 | Conditional Replacement | |
58 | ----------------------- | |
59 | ||
30c5ffd2 | 60 | This transformation, implemented in conditional_replacement, |
caac37c2 | 61 | replaces |
4ee9c684 | 62 | |
63 | bb0: | |
64 | if (cond) goto bb2; else goto bb1; | |
65 | bb1: | |
66 | bb2: | |
caac37c2 | 67 | x = PHI <0 (bb1), 1 (bb0), ...>; |
4ee9c684 | 68 | |
caac37c2 | 69 | with |
20e5647c | 70 | |
2ab0a163 | 71 | bb0: |
caac37c2 | 72 | x' = cond; |
73 | goto bb2; | |
2ab0a163 | 74 | bb2: |
caac37c2 | 75 | x = PHI <x' (bb0), ...>; |
4ee9c684 | 76 | |
caac37c2 | 77 | We remove bb1 as it becomes unreachable. This occurs often due to |
78 | gimplification of conditionals. | |
20e5647c | 79 | |
caac37c2 | 80 | Value Replacement |
81 | ----------------- | |
82 | ||
83 | This transformation, implemented in value_replacement, replaces | |
0beac6fc | 84 | |
85 | bb0: | |
caac37c2 | 86 | if (a != b) goto bb2; else goto bb1; |
0beac6fc | 87 | bb1: |
88 | bb2: | |
caac37c2 | 89 | x = PHI <a (bb1), b (bb0), ...>; |
0beac6fc | 90 | |
caac37c2 | 91 | with |
0beac6fc | 92 | |
93 | bb0: | |
0beac6fc | 94 | bb2: |
caac37c2 | 95 | x = PHI <b (bb0), ...>; |
96 | ||
97 | This opportunity can sometimes occur as a result of other | |
98 | optimizations. | |
0beac6fc | 99 | |
caac37c2 | 100 | ABS Replacement |
101 | --------------- | |
70512b93 | 102 | |
caac37c2 | 103 | This transformation, implemented in abs_replacement, replaces |
70512b93 | 104 | |
105 | bb0: | |
caac37c2 | 106 | if (a >= 0) goto bb2; else goto bb1; |
70512b93 | 107 | bb1: |
caac37c2 | 108 | x = -a; |
70512b93 | 109 | bb2: |
caac37c2 | 110 | x = PHI <x (bb1), a (bb0), ...>; |
70512b93 | 111 | |
caac37c2 | 112 | with |
70512b93 | 113 | |
114 | bb0: | |
caac37c2 | 115 | x' = ABS_EXPR< a >; |
70512b93 | 116 | bb2: |
caac37c2 | 117 | x = PHI <x' (bb0), ...>; |
118 | ||
119 | MIN/MAX Replacement | |
120 | ------------------- | |
70512b93 | 121 | |
caac37c2 | 122 | This transformation, minmax_replacement replaces |
194899bf | 123 | |
124 | bb0: | |
caac37c2 | 125 | if (a <= b) goto bb2; else goto bb1; |
194899bf | 126 | bb1: |
194899bf | 127 | bb2: |
caac37c2 | 128 | x = PHI <b (bb1), a (bb0), ...>; |
194899bf | 129 | |
caac37c2 | 130 | with |
194899bf | 131 | |
caac37c2 | 132 | bb0: |
133 | x' = MIN_EXPR (a, b) | |
134 | bb2: | |
135 | x = PHI <x' (bb0), ...>; | |
194899bf | 136 | |
30c5ffd2 | 137 | A similar transformation is done for MAX_EXPR. */ |
70512b93 | 138 | |
2a1990e9 | 139 | static unsigned int |
4ee9c684 | 140 | tree_ssa_phiopt (void) |
e6d0e152 | 141 | { |
142 | return tree_ssa_phiopt_worker (false); | |
143 | } | |
144 | ||
145 | /* This pass tries to transform conditional stores into unconditional | |
146 | ones, enabling further simplifications with the simpler then and else | |
147 | blocks. In particular it replaces this: | |
148 | ||
149 | bb0: | |
150 | if (cond) goto bb2; else goto bb1; | |
151 | bb1: | |
152 | *p = RHS | |
153 | bb2: | |
154 | ||
155 | with | |
156 | ||
157 | bb0: | |
158 | if (cond) goto bb1; else goto bb2; | |
159 | bb1: | |
160 | condtmp' = *p; | |
161 | bb2: | |
162 | condtmp = PHI <RHS, condtmp'> | |
163 | *p = condtmp | |
164 | ||
165 | This transformation can only be done under several constraints, | |
166 | documented below. */ | |
167 | ||
168 | static unsigned int | |
169 | tree_ssa_cs_elim (void) | |
170 | { | |
171 | return tree_ssa_phiopt_worker (true); | |
172 | } | |
173 | ||
174 | /* For conditional store replacement we need a temporary to | |
175 | put the old contents of the memory in. */ | |
176 | static tree condstoretemp; | |
177 | ||
178 | /* The core routine of conditional store replacement and normal | |
179 | phi optimizations. Both share much of the infrastructure in how | |
180 | to match applicable basic block patterns. DO_STORE_ELIM is true | |
181 | when we want to do conditional store replacement, false otherwise. */ | |
182 | static unsigned int | |
183 | tree_ssa_phiopt_worker (bool do_store_elim) | |
4ee9c684 | 184 | { |
185 | basic_block bb; | |
194899bf | 186 | basic_block *bb_order; |
187 | unsigned n, i; | |
1e4b21e3 | 188 | bool cfgchanged = false; |
e6d0e152 | 189 | struct pointer_set_t *nontrap = 0; |
190 | ||
191 | if (do_store_elim) | |
192 | { | |
193 | condstoretemp = NULL_TREE; | |
194 | /* Calculate the set of non-trapping memory accesses. */ | |
195 | nontrap = get_non_trapping (); | |
196 | } | |
194899bf | 197 | |
198 | /* Search every basic block for COND_EXPR we may be able to optimize. | |
199 | ||
200 | We walk the blocks in order that guarantees that a block with | |
201 | a single predecessor is processed before the predecessor. | |
202 | This ensures that we collapse inner ifs before visiting the | |
203 | outer ones, and also that we do not try to visit a removed | |
204 | block. */ | |
205 | bb_order = blocks_in_phiopt_order (); | |
4d2e5d52 | 206 | n = n_basic_blocks - NUM_FIXED_BLOCKS; |
4ee9c684 | 207 | |
4d2e5d52 | 208 | for (i = 0; i < n; i++) |
4ee9c684 | 209 | { |
33784d89 | 210 | tree cond_expr; |
211 | tree phi; | |
212 | basic_block bb1, bb2; | |
213 | edge e1, e2; | |
194899bf | 214 | tree arg0, arg1; |
215 | ||
216 | bb = bb_order[i]; | |
20e5647c | 217 | |
33784d89 | 218 | cond_expr = last_stmt (bb); |
20e5647c | 219 | /* Check to see if the last statement is a COND_EXPR. */ |
33784d89 | 220 | if (!cond_expr |
221 | || TREE_CODE (cond_expr) != COND_EXPR) | |
222 | continue; | |
20e5647c | 223 | |
33784d89 | 224 | e1 = EDGE_SUCC (bb, 0); |
225 | bb1 = e1->dest; | |
226 | e2 = EDGE_SUCC (bb, 1); | |
227 | bb2 = e2->dest; | |
20e5647c | 228 | |
33784d89 | 229 | /* We cannot do the optimization on abnormal edges. */ |
230 | if ((e1->flags & EDGE_ABNORMAL) != 0 | |
231 | || (e2->flags & EDGE_ABNORMAL) != 0) | |
232 | continue; | |
20e5647c | 233 | |
33784d89 | 234 | /* If either bb1's succ or bb2 or bb2's succ is non NULL. */ |
ea091dfd | 235 | if (EDGE_COUNT (bb1->succs) == 0 |
33784d89 | 236 | || bb2 == NULL |
ea091dfd | 237 | || EDGE_COUNT (bb2->succs) == 0) |
33784d89 | 238 | continue; |
20e5647c | 239 | |
33784d89 | 240 | /* Find the bb which is the fall through to the other. */ |
241 | if (EDGE_SUCC (bb1, 0)->dest == bb2) | |
242 | ; | |
243 | else if (EDGE_SUCC (bb2, 0)->dest == bb1) | |
244 | { | |
245 | basic_block bb_tmp = bb1; | |
246 | edge e_tmp = e1; | |
247 | bb1 = bb2; | |
248 | bb2 = bb_tmp; | |
249 | e1 = e2; | |
250 | e2 = e_tmp; | |
251 | } | |
252 | else | |
253 | continue; | |
20e5647c | 254 | |
33784d89 | 255 | e1 = EDGE_SUCC (bb1, 0); |
20e5647c | 256 | |
33784d89 | 257 | /* Make sure that bb1 is just a fall through. */ |
db5ba14c | 258 | if (!single_succ_p (bb1) |
33784d89 | 259 | || (e1->flags & EDGE_FALLTHRU) == 0) |
260 | continue; | |
20e5647c | 261 | |
3472707f | 262 | /* Also make sure that bb1 only have one predecessor and that it |
263 | is bb. */ | |
ea091dfd | 264 | if (!single_pred_p (bb1) |
265 | || single_pred (bb1) != bb) | |
33784d89 | 266 | continue; |
20e5647c | 267 | |
e6d0e152 | 268 | if (do_store_elim) |
269 | { | |
270 | /* bb1 is the middle block, bb2 the join block, bb the split block, | |
271 | e1 the fallthrough edge from bb1 to bb2. We can't do the | |
272 | optimization if the join block has more than two predecessors. */ | |
273 | if (EDGE_COUNT (bb2->preds) > 2) | |
274 | continue; | |
275 | if (cond_store_replacement (bb1, bb2, e1, e2, nontrap)) | |
276 | cfgchanged = true; | |
277 | } | |
278 | else | |
279 | { | |
280 | phi = phi_nodes (bb2); | |
281 | ||
282 | /* Check to make sure that there is only one PHI node. | |
283 | TODO: we could do it with more than one iff the other PHI nodes | |
284 | have the same elements for these two edges. */ | |
285 | if (!phi || PHI_CHAIN (phi) != NULL) | |
286 | continue; | |
287 | ||
288 | arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx); | |
289 | arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx); | |
290 | ||
291 | /* Something is wrong if we cannot find the arguments in the PHI | |
292 | node. */ | |
293 | gcc_assert (arg0 != NULL && arg1 != NULL); | |
294 | ||
295 | /* Do the replacement of conditional if it can be done. */ | |
296 | if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
297 | cfgchanged = true; | |
298 | else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
299 | cfgchanged = true; | |
300 | else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
301 | cfgchanged = true; | |
302 | else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
303 | cfgchanged = true; | |
304 | } | |
194899bf | 305 | } |
306 | ||
307 | free (bb_order); | |
1e4b21e3 | 308 | |
e6d0e152 | 309 | if (do_store_elim) |
310 | pointer_set_destroy (nontrap); | |
311 | /* If the CFG has changed, we should cleanup the CFG. */ | |
312 | if (cfgchanged && do_store_elim) | |
313 | { | |
314 | /* In cond-store replacement we have added some loads on edges | |
315 | and new VOPS (as we moved the store, and created a load). */ | |
316 | bsi_commit_edge_inserts (); | |
317 | return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals; | |
318 | } | |
319 | else if (cfgchanged) | |
320 | return TODO_cleanup_cfg; | |
321 | return 0; | |
194899bf | 322 | } |
323 | ||
324 | /* Returns the list of basic blocks in the function in an order that guarantees | |
325 | that if a block X has just a single predecessor Y, then Y is after X in the | |
326 | ordering. */ | |
327 | ||
8530c7be | 328 | basic_block * |
194899bf | 329 | blocks_in_phiopt_order (void) |
330 | { | |
331 | basic_block x, y; | |
945865c5 | 332 | basic_block *order = XNEWVEC (basic_block, n_basic_blocks); |
4d2e5d52 | 333 | unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS; |
334 | unsigned np, i; | |
335 | sbitmap visited = sbitmap_alloc (last_basic_block); | |
194899bf | 336 | |
4d2e5d52 | 337 | #define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index)) |
338 | #define VISITED_P(BB) (TEST_BIT (visited, (BB)->index)) | |
194899bf | 339 | |
340 | sbitmap_zero (visited); | |
341 | ||
342 | MARK_VISITED (ENTRY_BLOCK_PTR); | |
343 | FOR_EACH_BB (x) | |
344 | { | |
345 | if (VISITED_P (x)) | |
346 | continue; | |
347 | ||
348 | /* Walk the predecessors of x as long as they have precisely one | |
349 | predecessor and add them to the list, so that they get stored | |
350 | after x. */ | |
351 | for (y = x, np = 1; | |
352 | single_pred_p (y) && !VISITED_P (single_pred (y)); | |
353 | y = single_pred (y)) | |
354 | np++; | |
355 | for (y = x, i = n - np; | |
356 | single_pred_p (y) && !VISITED_P (single_pred (y)); | |
357 | y = single_pred (y), i++) | |
358 | { | |
359 | order[i] = y; | |
360 | MARK_VISITED (y); | |
2ab0a163 | 361 | } |
194899bf | 362 | order[i] = y; |
363 | MARK_VISITED (y); | |
364 | ||
365 | gcc_assert (i == n - 1); | |
366 | n -= np; | |
4ee9c684 | 367 | } |
194899bf | 368 | |
369 | sbitmap_free (visited); | |
370 | gcc_assert (n == 0); | |
371 | return order; | |
372 | ||
373 | #undef MARK_VISITED | |
374 | #undef VISITED_P | |
4ee9c684 | 375 | } |
376 | ||
47aaf6e6 | 377 | |
70512b93 | 378 | /* Return TRUE if block BB has no executable statements, otherwise return |
379 | FALSE. */ | |
47aaf6e6 | 380 | |
c91e8223 | 381 | bool |
47aaf6e6 | 382 | empty_block_p (basic_block bb) |
70512b93 | 383 | { |
47aaf6e6 | 384 | block_stmt_iterator bsi; |
70512b93 | 385 | |
386 | /* BB must have no executable statements. */ | |
47aaf6e6 | 387 | bsi = bsi_start (bb); |
388 | while (!bsi_end_p (bsi) | |
389 | && (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR | |
390 | || IS_EMPTY_STMT (bsi_stmt (bsi)))) | |
391 | bsi_next (&bsi); | |
20e5647c | 392 | |
47aaf6e6 | 393 | if (!bsi_end_p (bsi)) |
70512b93 | 394 | return false; |
395 | ||
396 | return true; | |
397 | } | |
398 | ||
fccee353 | 399 | /* Replace PHI node element whose edge is E in block BB with variable NEW. |
33784d89 | 400 | Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK |
902929aa | 401 | is known to have two edges, one of which must reach BB). */ |
402 | ||
403 | static void | |
a4844041 | 404 | replace_phi_edge_with_variable (basic_block cond_block, |
f0d6e81c | 405 | edge e, tree phi, tree new_tree) |
902929aa | 406 | { |
a4844041 | 407 | basic_block bb = bb_for_stmt (phi); |
0e1a77e1 | 408 | basic_block block_to_remove; |
33784d89 | 409 | block_stmt_iterator bsi; |
410 | ||
20e5647c | 411 | /* Change the PHI argument to new. */ |
f0d6e81c | 412 | SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree); |
0e1a77e1 | 413 | |
0e1a77e1 | 414 | /* Remove the empty basic block. */ |
cd665a06 | 415 | if (EDGE_SUCC (cond_block, 0)->dest == bb) |
902929aa | 416 | { |
cd665a06 | 417 | EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU; |
418 | EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); | |
81c5be57 | 419 | EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE; |
420 | EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count; | |
0e1a77e1 | 421 | |
cd665a06 | 422 | block_to_remove = EDGE_SUCC (cond_block, 1)->dest; |
902929aa | 423 | } |
424 | else | |
425 | { | |
cd665a06 | 426 | EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU; |
427 | EDGE_SUCC (cond_block, 1)->flags | |
902929aa | 428 | &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); |
81c5be57 | 429 | EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE; |
430 | EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count; | |
0e1a77e1 | 431 | |
cd665a06 | 432 | block_to_remove = EDGE_SUCC (cond_block, 0)->dest; |
902929aa | 433 | } |
0e1a77e1 | 434 | delete_basic_block (block_to_remove); |
20e5647c | 435 | |
902929aa | 436 | /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ |
437 | bsi = bsi_last (cond_block); | |
f2428b62 | 438 | bsi_remove (&bsi, true); |
20e5647c | 439 | |
902929aa | 440 | if (dump_file && (dump_flags & TDF_DETAILS)) |
441 | fprintf (dump_file, | |
442 | "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n", | |
443 | cond_block->index, | |
444 | bb->index); | |
445 | } | |
446 | ||
447 | /* The function conditional_replacement does the main work of doing the | |
448 | conditional replacement. Return true if the replacement is done. | |
449 | Otherwise return false. | |
450 | BB is the basic block where the replacement is going to be done on. ARG0 | |
dac49aa5 | 451 | is argument 0 from PHI. Likewise for ARG1. */ |
902929aa | 452 | |
453 | static bool | |
33784d89 | 454 | conditional_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 455 | edge e0, edge e1, tree phi, |
33784d89 | 456 | tree arg0, tree arg1) |
902929aa | 457 | { |
458 | tree result; | |
459 | tree old_result = NULL; | |
f0d6e81c | 460 | tree new_stmt, cond; |
902929aa | 461 | block_stmt_iterator bsi; |
462 | edge true_edge, false_edge; | |
463 | tree new_var = NULL; | |
33784d89 | 464 | tree new_var1; |
902929aa | 465 | |
466 | /* The PHI arguments have the constants 0 and 1, then convert | |
467 | it to the conditional. */ | |
468 | if ((integer_zerop (arg0) && integer_onep (arg1)) | |
469 | || (integer_zerop (arg1) && integer_onep (arg0))) | |
470 | ; | |
471 | else | |
472 | return false; | |
20e5647c | 473 | |
33784d89 | 474 | if (!empty_block_p (middle_bb)) |
902929aa | 475 | return false; |
20e5647c | 476 | |
4ee9c684 | 477 | /* If the condition is not a naked SSA_NAME and its type does not |
2ab0a163 | 478 | match the type of the result, then we have to create a new |
479 | variable to optimize this case as it would likely create | |
480 | non-gimple code when the condition was converted to the | |
481 | result's type. */ | |
33784d89 | 482 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
4ee9c684 | 483 | result = PHI_RESULT (phi); |
484 | if (TREE_CODE (cond) != SSA_NAME | |
c8ca3ee7 | 485 | && !useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (cond))) |
ae5a4794 | 486 | { |
b2a02a0e | 487 | tree tmp; |
488 | ||
489 | if (!COMPARISON_CLASS_P (cond)) | |
490 | return false; | |
491 | ||
492 | tmp = create_tmp_var (TREE_TYPE (cond), NULL); | |
987392e5 | 493 | add_referenced_var (tmp); |
b2a02a0e | 494 | new_var = make_ssa_name (tmp, NULL); |
ae5a4794 | 495 | old_result = cond; |
496 | cond = new_var; | |
497 | } | |
20e5647c | 498 | |
4ee9c684 | 499 | /* If the condition was a naked SSA_NAME and the type is not the |
2ab0a163 | 500 | same as the type of the result, then convert the type of the |
501 | condition. */ | |
c8ca3ee7 | 502 | if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (cond))) |
4ee9c684 | 503 | cond = fold_convert (TREE_TYPE (result), cond); |
20e5647c | 504 | |
4ee9c684 | 505 | /* We need to know which is the true edge and which is the false |
2ab0a163 | 506 | edge so that we know when to invert the condition below. */ |
33784d89 | 507 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
20e5647c | 508 | |
1fa68a1f | 509 | /* Insert our new statement at the end of conditional block before the |
33784d89 | 510 | COND_EXPR. */ |
511 | bsi = bsi_last (cond_bb); | |
512 | bsi_insert_before (&bsi, build_empty_stmt (), BSI_NEW_STMT); | |
20e5647c | 513 | |
ae5a4794 | 514 | if (old_result) |
515 | { | |
516 | tree new1; | |
20e5647c | 517 | |
194899bf | 518 | new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result), |
519 | TREE_OPERAND (old_result, 0), | |
520 | TREE_OPERAND (old_result, 1)); | |
20e5647c | 521 | |
41076ef6 | 522 | new1 = build_gimple_modify_stmt (new_var, new1); |
b2a02a0e | 523 | SSA_NAME_DEF_STMT (new_var) = new1; |
524 | ||
ae5a4794 | 525 | bsi_insert_after (&bsi, new1, BSI_NEW_STMT); |
526 | } | |
20e5647c | 527 | |
33784d89 | 528 | new_var1 = duplicate_ssa_name (PHI_RESULT (phi), NULL); |
20e5647c | 529 | |
530 | ||
4ee9c684 | 531 | /* At this point we know we have a COND_EXPR with two successors. |
2ab0a163 | 532 | One successor is BB, the other successor is an empty block which |
533 | falls through into BB. | |
20e5647c | 534 | |
2ab0a163 | 535 | There is a single PHI node at the join point (BB) and its arguments |
536 | are constants (0, 1). | |
20e5647c | 537 | |
2ab0a163 | 538 | So, given the condition COND, and the two PHI arguments, we can |
20e5647c | 539 | rewrite this PHI into non-branching code: |
540 | ||
2ab0a163 | 541 | dest = (COND) or dest = COND' |
20e5647c | 542 | |
2ab0a163 | 543 | We use the condition as-is if the argument associated with the |
544 | true edge has the value one or the argument associated with the | |
545 | false edge as the value zero. Note that those conditions are not | |
546 | the same since only one of the outgoing edges from the COND_EXPR | |
547 | will directly reach BB and thus be associated with an argument. */ | |
33784d89 | 548 | if ((e0 == true_edge && integer_onep (arg0)) |
549 | || (e0 == false_edge && integer_zerop (arg0)) | |
550 | || (e1 == true_edge && integer_onep (arg1)) | |
551 | || (e1 == false_edge && integer_zerop (arg1))) | |
4ee9c684 | 552 | { |
f0d6e81c | 553 | new_stmt = build_gimple_modify_stmt (new_var1, cond); |
4ee9c684 | 554 | } |
555 | else | |
556 | { | |
ae5a4794 | 557 | tree cond1 = invert_truthvalue (cond); |
20e5647c | 558 | |
ae5a4794 | 559 | cond = cond1; |
b2a02a0e | 560 | |
ae5a4794 | 561 | /* If what we get back is a conditional expression, there is no |
0beac6fc | 562 | way that it can be gimple. */ |
ae5a4794 | 563 | if (TREE_CODE (cond) == COND_EXPR) |
33784d89 | 564 | { |
565 | release_ssa_name (new_var1); | |
20e5647c | 566 | return false; |
33784d89 | 567 | } |
ae5a4794 | 568 | |
b2a02a0e | 569 | /* If COND is not something we can expect to be reducible to a GIMPLE |
570 | condition, return early. */ | |
571 | if (is_gimple_cast (cond)) | |
572 | cond1 = TREE_OPERAND (cond, 0); | |
573 | if (TREE_CODE (cond1) == TRUTH_NOT_EXPR | |
574 | && !is_gimple_val (TREE_OPERAND (cond1, 0))) | |
575 | { | |
576 | release_ssa_name (new_var1); | |
577 | return false; | |
578 | } | |
579 | ||
ae5a4794 | 580 | /* If what we get back is not gimple try to create it as gimple by |
dac49aa5 | 581 | using a temporary variable. */ |
4ee9c684 | 582 | if (is_gimple_cast (cond) |
583 | && !is_gimple_val (TREE_OPERAND (cond, 0))) | |
2ab0a163 | 584 | { |
b2a02a0e | 585 | tree op0, tmp, cond_tmp; |
20e5647c | 586 | |
b2a02a0e | 587 | /* Only "real" casts are OK here, not everything that is |
588 | acceptable to is_gimple_cast. Make sure we don't do | |
589 | anything stupid here. */ | |
590 | gcc_assert (TREE_CODE (cond) == NOP_EXPR | |
591 | || TREE_CODE (cond) == CONVERT_EXPR); | |
592 | ||
593 | op0 = TREE_OPERAND (cond, 0); | |
594 | tmp = create_tmp_var (TREE_TYPE (op0), NULL); | |
987392e5 | 595 | add_referenced_var (tmp); |
b2a02a0e | 596 | cond_tmp = make_ssa_name (tmp, NULL); |
f0d6e81c | 597 | new_stmt = build_gimple_modify_stmt (cond_tmp, op0); |
598 | SSA_NAME_DEF_STMT (cond_tmp) = new_stmt; | |
b2a02a0e | 599 | |
f0d6e81c | 600 | bsi_insert_after (&bsi, new_stmt, BSI_NEW_STMT); |
b2a02a0e | 601 | cond = fold_convert (TREE_TYPE (result), cond_tmp); |
33784d89 | 602 | } |
4ee9c684 | 603 | |
f0d6e81c | 604 | new_stmt = build_gimple_modify_stmt (new_var1, cond); |
4ee9c684 | 605 | } |
20e5647c | 606 | |
f0d6e81c | 607 | bsi_insert_after (&bsi, new_stmt, BSI_NEW_STMT); |
20e5647c | 608 | |
f0d6e81c | 609 | SSA_NAME_DEF_STMT (new_var1) = new_stmt; |
20e5647c | 610 | |
a4844041 | 611 | replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1); |
902929aa | 612 | |
4ee9c684 | 613 | /* Note that we optimized this PHI. */ |
614 | return true; | |
615 | } | |
616 | ||
0beac6fc | 617 | /* The function value_replacement does the main work of doing the value |
618 | replacement. Return true if the replacement is done. Otherwise return | |
619 | false. | |
620 | BB is the basic block where the replacement is going to be done on. ARG0 | |
dac49aa5 | 621 | is argument 0 from the PHI. Likewise for ARG1. */ |
0beac6fc | 622 | |
623 | static bool | |
33784d89 | 624 | value_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 625 | edge e0, edge e1, tree phi, |
33784d89 | 626 | tree arg0, tree arg1) |
0beac6fc | 627 | { |
33784d89 | 628 | tree cond; |
0beac6fc | 629 | edge true_edge, false_edge; |
630 | ||
631 | /* If the type says honor signed zeros we cannot do this | |
dac49aa5 | 632 | optimization. */ |
0beac6fc | 633 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) |
634 | return false; | |
635 | ||
33784d89 | 636 | if (!empty_block_p (middle_bb)) |
0beac6fc | 637 | return false; |
638 | ||
33784d89 | 639 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
0beac6fc | 640 | |
641 | /* This transformation is only valid for equality comparisons. */ | |
642 | if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR) | |
643 | return false; | |
644 | ||
645 | /* We need to know which is the true edge and which is the false | |
646 | edge so that we know if have abs or negative abs. */ | |
33784d89 | 647 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
0beac6fc | 648 | |
649 | /* At this point we know we have a COND_EXPR with two successors. | |
650 | One successor is BB, the other successor is an empty block which | |
651 | falls through into BB. | |
652 | ||
653 | The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR. | |
654 | ||
655 | There is a single PHI node at the join point (BB) with two arguments. | |
656 | ||
657 | We now need to verify that the two arguments in the PHI node match | |
658 | the two arguments to the equality comparison. */ | |
20e5647c | 659 | |
5373158f | 660 | if ((operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 0)) |
661 | && operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 1))) | |
662 | || (operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 0)) | |
663 | && operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 1)))) | |
0beac6fc | 664 | { |
665 | edge e; | |
666 | tree arg; | |
667 | ||
50737d20 | 668 | /* For NE_EXPR, we want to build an assignment result = arg where |
669 | arg is the PHI argument associated with the true edge. For | |
670 | EQ_EXPR we want the PHI argument associated with the false edge. */ | |
0beac6fc | 671 | e = (TREE_CODE (cond) == NE_EXPR ? true_edge : false_edge); |
50737d20 | 672 | |
673 | /* Unfortunately, E may not reach BB (it may instead have gone to | |
674 | OTHER_BLOCK). If that is the case, then we want the single outgoing | |
675 | edge from OTHER_BLOCK which reaches BB and represents the desired | |
676 | path from COND_BLOCK. */ | |
33784d89 | 677 | if (e->dest == middle_bb) |
ea091dfd | 678 | e = single_succ_edge (e->dest); |
50737d20 | 679 | |
680 | /* Now we know the incoming edge to BB that has the argument for the | |
681 | RHS of our new assignment statement. */ | |
33784d89 | 682 | if (e0 == e) |
0beac6fc | 683 | arg = arg0; |
684 | else | |
685 | arg = arg1; | |
686 | ||
a4844041 | 687 | replace_phi_edge_with_variable (cond_bb, e1, phi, arg); |
0beac6fc | 688 | |
689 | /* Note that we optimized this PHI. */ | |
690 | return true; | |
691 | } | |
692 | return false; | |
693 | } | |
694 | ||
194899bf | 695 | /* The function minmax_replacement does the main work of doing the minmax |
696 | replacement. Return true if the replacement is done. Otherwise return | |
697 | false. | |
698 | BB is the basic block where the replacement is going to be done on. ARG0 | |
699 | is argument 0 from the PHI. Likewise for ARG1. */ | |
700 | ||
701 | static bool | |
702 | minmax_replacement (basic_block cond_bb, basic_block middle_bb, | |
a4844041 | 703 | edge e0, edge e1, tree phi, |
194899bf | 704 | tree arg0, tree arg1) |
705 | { | |
706 | tree result, type; | |
f0d6e81c | 707 | tree cond, new_stmt; |
194899bf | 708 | edge true_edge, false_edge; |
709 | enum tree_code cmp, minmax, ass_code; | |
710 | tree smaller, larger, arg_true, arg_false; | |
711 | block_stmt_iterator bsi, bsi_from; | |
712 | ||
713 | type = TREE_TYPE (PHI_RESULT (phi)); | |
714 | ||
715 | /* The optimization may be unsafe due to NaNs. */ | |
716 | if (HONOR_NANS (TYPE_MODE (type))) | |
717 | return false; | |
718 | ||
719 | cond = COND_EXPR_COND (last_stmt (cond_bb)); | |
720 | cmp = TREE_CODE (cond); | |
721 | result = PHI_RESULT (phi); | |
722 | ||
723 | /* This transformation is only valid for order comparisons. Record which | |
724 | operand is smaller/larger if the result of the comparison is true. */ | |
725 | if (cmp == LT_EXPR || cmp == LE_EXPR) | |
726 | { | |
727 | smaller = TREE_OPERAND (cond, 0); | |
728 | larger = TREE_OPERAND (cond, 1); | |
729 | } | |
730 | else if (cmp == GT_EXPR || cmp == GE_EXPR) | |
731 | { | |
732 | smaller = TREE_OPERAND (cond, 1); | |
733 | larger = TREE_OPERAND (cond, 0); | |
734 | } | |
735 | else | |
736 | return false; | |
737 | ||
738 | /* We need to know which is the true edge and which is the false | |
739 | edge so that we know if have abs or negative abs. */ | |
740 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); | |
741 | ||
742 | /* Forward the edges over the middle basic block. */ | |
743 | if (true_edge->dest == middle_bb) | |
744 | true_edge = EDGE_SUCC (true_edge->dest, 0); | |
745 | if (false_edge->dest == middle_bb) | |
746 | false_edge = EDGE_SUCC (false_edge->dest, 0); | |
747 | ||
748 | if (true_edge == e0) | |
749 | { | |
750 | gcc_assert (false_edge == e1); | |
751 | arg_true = arg0; | |
752 | arg_false = arg1; | |
753 | } | |
754 | else | |
755 | { | |
756 | gcc_assert (false_edge == e0); | |
757 | gcc_assert (true_edge == e1); | |
758 | arg_true = arg1; | |
759 | arg_false = arg0; | |
760 | } | |
761 | ||
762 | if (empty_block_p (middle_bb)) | |
763 | { | |
764 | if (operand_equal_for_phi_arg_p (arg_true, smaller) | |
765 | && operand_equal_for_phi_arg_p (arg_false, larger)) | |
766 | { | |
767 | /* Case | |
768 | ||
769 | if (smaller < larger) | |
770 | rslt = smaller; | |
771 | else | |
772 | rslt = larger; */ | |
773 | minmax = MIN_EXPR; | |
774 | } | |
775 | else if (operand_equal_for_phi_arg_p (arg_false, smaller) | |
776 | && operand_equal_for_phi_arg_p (arg_true, larger)) | |
777 | minmax = MAX_EXPR; | |
778 | else | |
779 | return false; | |
780 | } | |
781 | else | |
782 | { | |
783 | /* Recognize the following case, assuming d <= u: | |
784 | ||
785 | if (a <= u) | |
786 | b = MAX (a, d); | |
787 | x = PHI <b, u> | |
788 | ||
789 | This is equivalent to | |
790 | ||
791 | b = MAX (a, d); | |
792 | x = MIN (b, u); */ | |
793 | ||
794 | tree assign = last_and_only_stmt (middle_bb); | |
795 | tree lhs, rhs, op0, op1, bound; | |
796 | ||
797 | if (!assign | |
35cc02b5 | 798 | || TREE_CODE (assign) != GIMPLE_MODIFY_STMT) |
194899bf | 799 | return false; |
800 | ||
35cc02b5 | 801 | lhs = GIMPLE_STMT_OPERAND (assign, 0); |
802 | rhs = GIMPLE_STMT_OPERAND (assign, 1); | |
194899bf | 803 | ass_code = TREE_CODE (rhs); |
804 | if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) | |
805 | return false; | |
806 | op0 = TREE_OPERAND (rhs, 0); | |
807 | op1 = TREE_OPERAND (rhs, 1); | |
808 | ||
809 | if (true_edge->src == middle_bb) | |
810 | { | |
811 | /* We got here if the condition is true, i.e., SMALLER < LARGER. */ | |
812 | if (!operand_equal_for_phi_arg_p (lhs, arg_true)) | |
813 | return false; | |
814 | ||
815 | if (operand_equal_for_phi_arg_p (arg_false, larger)) | |
816 | { | |
817 | /* Case | |
818 | ||
819 | if (smaller < larger) | |
820 | { | |
821 | r' = MAX_EXPR (smaller, bound) | |
822 | } | |
823 | r = PHI <r', larger> --> to be turned to MIN_EXPR. */ | |
824 | if (ass_code != MAX_EXPR) | |
825 | return false; | |
826 | ||
827 | minmax = MIN_EXPR; | |
828 | if (operand_equal_for_phi_arg_p (op0, smaller)) | |
829 | bound = op1; | |
830 | else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
831 | bound = op0; | |
832 | else | |
833 | return false; | |
834 | ||
835 | /* We need BOUND <= LARGER. */ | |
49d00087 | 836 | if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, |
837 | bound, larger))) | |
194899bf | 838 | return false; |
839 | } | |
840 | else if (operand_equal_for_phi_arg_p (arg_false, smaller)) | |
841 | { | |
842 | /* Case | |
843 | ||
844 | if (smaller < larger) | |
845 | { | |
846 | r' = MIN_EXPR (larger, bound) | |
847 | } | |
848 | r = PHI <r', smaller> --> to be turned to MAX_EXPR. */ | |
849 | if (ass_code != MIN_EXPR) | |
850 | return false; | |
851 | ||
852 | minmax = MAX_EXPR; | |
853 | if (operand_equal_for_phi_arg_p (op0, larger)) | |
854 | bound = op1; | |
855 | else if (operand_equal_for_phi_arg_p (op1, larger)) | |
856 | bound = op0; | |
857 | else | |
858 | return false; | |
859 | ||
860 | /* We need BOUND >= SMALLER. */ | |
49d00087 | 861 | if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, |
862 | bound, smaller))) | |
194899bf | 863 | return false; |
864 | } | |
865 | else | |
866 | return false; | |
867 | } | |
868 | else | |
869 | { | |
870 | /* We got here if the condition is false, i.e., SMALLER > LARGER. */ | |
871 | if (!operand_equal_for_phi_arg_p (lhs, arg_false)) | |
872 | return false; | |
873 | ||
874 | if (operand_equal_for_phi_arg_p (arg_true, larger)) | |
875 | { | |
876 | /* Case | |
877 | ||
878 | if (smaller > larger) | |
879 | { | |
880 | r' = MIN_EXPR (smaller, bound) | |
881 | } | |
882 | r = PHI <r', larger> --> to be turned to MAX_EXPR. */ | |
883 | if (ass_code != MIN_EXPR) | |
884 | return false; | |
885 | ||
886 | minmax = MAX_EXPR; | |
887 | if (operand_equal_for_phi_arg_p (op0, smaller)) | |
888 | bound = op1; | |
889 | else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
890 | bound = op0; | |
891 | else | |
892 | return false; | |
893 | ||
894 | /* We need BOUND >= LARGER. */ | |
49d00087 | 895 | if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, |
896 | bound, larger))) | |
194899bf | 897 | return false; |
898 | } | |
899 | else if (operand_equal_for_phi_arg_p (arg_true, smaller)) | |
900 | { | |
901 | /* Case | |
902 | ||
903 | if (smaller > larger) | |
904 | { | |
905 | r' = MAX_EXPR (larger, bound) | |
906 | } | |
907 | r = PHI <r', smaller> --> to be turned to MIN_EXPR. */ | |
908 | if (ass_code != MAX_EXPR) | |
909 | return false; | |
910 | ||
911 | minmax = MIN_EXPR; | |
912 | if (operand_equal_for_phi_arg_p (op0, larger)) | |
913 | bound = op1; | |
914 | else if (operand_equal_for_phi_arg_p (op1, larger)) | |
915 | bound = op0; | |
916 | else | |
917 | return false; | |
918 | ||
919 | /* We need BOUND <= SMALLER. */ | |
49d00087 | 920 | if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, |
921 | bound, smaller))) | |
194899bf | 922 | return false; |
923 | } | |
924 | else | |
925 | return false; | |
926 | } | |
927 | ||
928 | /* Move the statement from the middle block. */ | |
929 | bsi = bsi_last (cond_bb); | |
930 | bsi_from = bsi_last (middle_bb); | |
931 | bsi_move_before (&bsi_from, &bsi); | |
932 | } | |
933 | ||
934 | /* Emit the statement to compute min/max. */ | |
935 | result = duplicate_ssa_name (PHI_RESULT (phi), NULL); | |
f0d6e81c | 936 | new_stmt = build_gimple_modify_stmt (result, build2 (minmax, type, arg0, arg1)); |
937 | SSA_NAME_DEF_STMT (result) = new_stmt; | |
194899bf | 938 | bsi = bsi_last (cond_bb); |
f0d6e81c | 939 | bsi_insert_before (&bsi, new_stmt, BSI_NEW_STMT); |
194899bf | 940 | |
a4844041 | 941 | replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
194899bf | 942 | return true; |
943 | } | |
944 | ||
70512b93 | 945 | /* The function absolute_replacement does the main work of doing the absolute |
946 | replacement. Return true if the replacement is done. Otherwise return | |
947 | false. | |
948 | bb is the basic block where the replacement is going to be done on. arg0 | |
f7f07c95 | 949 | is argument 0 from the phi. Likewise for arg1. */ |
33784d89 | 950 | |
70512b93 | 951 | static bool |
33784d89 | 952 | abs_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 953 | edge e0 ATTRIBUTE_UNUSED, edge e1, |
20e5647c | 954 | tree phi, tree arg0, tree arg1) |
70512b93 | 955 | { |
956 | tree result; | |
f0d6e81c | 957 | tree new_stmt, cond; |
70512b93 | 958 | block_stmt_iterator bsi; |
959 | edge true_edge, false_edge; | |
194899bf | 960 | tree assign; |
70512b93 | 961 | edge e; |
194899bf | 962 | tree rhs, lhs; |
70512b93 | 963 | bool negate; |
964 | enum tree_code cond_code; | |
965 | ||
966 | /* If the type says honor signed zeros we cannot do this | |
dac49aa5 | 967 | optimization. */ |
70512b93 | 968 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) |
969 | return false; | |
970 | ||
70512b93 | 971 | /* OTHER_BLOCK must have only one executable statement which must have the |
972 | form arg0 = -arg1 or arg1 = -arg0. */ | |
70512b93 | 973 | |
194899bf | 974 | assign = last_and_only_stmt (middle_bb); |
70512b93 | 975 | /* If we did not find the proper negation assignment, then we can not |
976 | optimize. */ | |
977 | if (assign == NULL) | |
978 | return false; | |
194899bf | 979 | |
980 | /* If we got here, then we have found the only executable statement | |
981 | in OTHER_BLOCK. If it is anything other than arg = -arg1 or | |
982 | arg1 = -arg0, then we can not optimize. */ | |
35cc02b5 | 983 | if (TREE_CODE (assign) != GIMPLE_MODIFY_STMT) |
194899bf | 984 | return false; |
985 | ||
35cc02b5 | 986 | lhs = GIMPLE_STMT_OPERAND (assign, 0); |
987 | rhs = GIMPLE_STMT_OPERAND (assign, 1); | |
194899bf | 988 | |
989 | if (TREE_CODE (rhs) != NEGATE_EXPR) | |
990 | return false; | |
991 | ||
992 | rhs = TREE_OPERAND (rhs, 0); | |
993 | ||
994 | /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */ | |
995 | if (!(lhs == arg0 && rhs == arg1) | |
996 | && !(lhs == arg1 && rhs == arg0)) | |
997 | return false; | |
70512b93 | 998 | |
33784d89 | 999 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
70512b93 | 1000 | result = PHI_RESULT (phi); |
1001 | ||
1002 | /* Only relationals comparing arg[01] against zero are interesting. */ | |
1003 | cond_code = TREE_CODE (cond); | |
1004 | if (cond_code != GT_EXPR && cond_code != GE_EXPR | |
1005 | && cond_code != LT_EXPR && cond_code != LE_EXPR) | |
1006 | return false; | |
1007 | ||
dac49aa5 | 1008 | /* Make sure the conditional is arg[01] OP y. */ |
70512b93 | 1009 | if (TREE_OPERAND (cond, 0) != rhs) |
1010 | return false; | |
1011 | ||
1012 | if (FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1))) | |
1013 | ? real_zerop (TREE_OPERAND (cond, 1)) | |
1014 | : integer_zerop (TREE_OPERAND (cond, 1))) | |
1015 | ; | |
1016 | else | |
1017 | return false; | |
1018 | ||
1019 | /* We need to know which is the true edge and which is the false | |
1020 | edge so that we know if have abs or negative abs. */ | |
33784d89 | 1021 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
70512b93 | 1022 | |
1023 | /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we | |
1024 | will need to negate the result. Similarly for LT_EXPR/LE_EXPR if | |
1025 | the false edge goes to OTHER_BLOCK. */ | |
1026 | if (cond_code == GT_EXPR || cond_code == GE_EXPR) | |
1027 | e = true_edge; | |
1028 | else | |
1029 | e = false_edge; | |
20e5647c | 1030 | |
33784d89 | 1031 | if (e->dest == middle_bb) |
70512b93 | 1032 | negate = true; |
1033 | else | |
1034 | negate = false; | |
20e5647c | 1035 | |
33784d89 | 1036 | result = duplicate_ssa_name (result, NULL); |
20e5647c | 1037 | |
70512b93 | 1038 | if (negate) |
b2a02a0e | 1039 | { |
1040 | tree tmp = create_tmp_var (TREE_TYPE (result), NULL); | |
987392e5 | 1041 | add_referenced_var (tmp); |
b2a02a0e | 1042 | lhs = make_ssa_name (tmp, NULL); |
1043 | } | |
70512b93 | 1044 | else |
1045 | lhs = result; | |
1046 | ||
dac49aa5 | 1047 | /* Build the modify expression with abs expression. */ |
f0d6e81c | 1048 | new_stmt = build_gimple_modify_stmt (lhs, |
1049 | build1 (ABS_EXPR, TREE_TYPE (lhs), rhs)); | |
1050 | SSA_NAME_DEF_STMT (lhs) = new_stmt; | |
70512b93 | 1051 | |
33784d89 | 1052 | bsi = bsi_last (cond_bb); |
f0d6e81c | 1053 | bsi_insert_before (&bsi, new_stmt, BSI_NEW_STMT); |
70512b93 | 1054 | |
1055 | if (negate) | |
1056 | { | |
20e5647c | 1057 | /* Get the right BSI. We want to insert after the recently |
70512b93 | 1058 | added ABS_EXPR statement (which we know is the first statement |
1059 | in the block. */ | |
f0d6e81c | 1060 | new_stmt = build_gimple_modify_stmt (result, |
1061 | build1 (NEGATE_EXPR, TREE_TYPE (lhs), | |
1062 | lhs)); | |
1063 | SSA_NAME_DEF_STMT (result) = new_stmt; | |
70512b93 | 1064 | |
f0d6e81c | 1065 | bsi_insert_after (&bsi, new_stmt, BSI_NEW_STMT); |
70512b93 | 1066 | } |
20e5647c | 1067 | |
a4844041 | 1068 | replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
70512b93 | 1069 | |
1070 | /* Note that we optimized this PHI. */ | |
1071 | return true; | |
1072 | } | |
1073 | ||
e6d0e152 | 1074 | /* Auxiliary functions to determine the set of memory accesses which |
1075 | can't trap because they are preceded by accesses to the same memory | |
1076 | portion. We do that for INDIRECT_REFs, so we only need to track | |
1077 | the SSA_NAME of the pointer indirectly referenced. The algorithm | |
1078 | simply is a walk over all instructions in dominator order. When | |
1079 | we see an INDIRECT_REF we determine if we've already seen a same | |
1080 | ref anywhere up to the root of the dominator tree. If we do the | |
af4f74fa | 1081 | current access can't trap. If we don't see any dominating access |
e6d0e152 | 1082 | the current access might trap, but might also make later accesses |
af4f74fa | 1083 | non-trapping, so we remember it. We need to be careful with loads |
1084 | or stores, for instance a load might not trap, while a store would, | |
1085 | so if we see a dominating read access this doesn't mean that a later | |
1086 | write access would not trap. Hence we also need to differentiate the | |
1087 | type of access(es) seen. | |
1088 | ||
1089 | ??? We currently are very conservative and assume that a load might | |
1090 | trap even if a store doesn't (write-only memory). This probably is | |
1091 | overly conservative. */ | |
e6d0e152 | 1092 | |
1093 | /* A hash-table of SSA_NAMEs, and in which basic block an INDIRECT_REF | |
1094 | through it was seen, which would constitute a no-trap region for | |
1095 | same accesses. */ | |
1096 | struct name_to_bb | |
1097 | { | |
1098 | tree ssa_name; | |
1099 | basic_block bb; | |
af4f74fa | 1100 | unsigned store : 1; |
e6d0e152 | 1101 | }; |
1102 | ||
1103 | /* The hash table for remembering what we've seen. */ | |
1104 | static htab_t seen_ssa_names; | |
1105 | ||
1106 | /* The set of INDIRECT_REFs which can't trap. */ | |
1107 | static struct pointer_set_t *nontrap_set; | |
1108 | ||
1109 | /* The hash function, based on the pointer to the pointer SSA_NAME. */ | |
1110 | static hashval_t | |
1111 | name_to_bb_hash (const void *p) | |
1112 | { | |
1113 | tree n = ((struct name_to_bb *)p)->ssa_name; | |
af4f74fa | 1114 | return htab_hash_pointer (n) ^ ((struct name_to_bb *)p)->store; |
e6d0e152 | 1115 | } |
1116 | ||
1117 | /* The equality function of *P1 and *P2. SSA_NAMEs are shared, so | |
1118 | it's enough to simply compare them for equality. */ | |
1119 | static int | |
1120 | name_to_bb_eq (const void *p1, const void *p2) | |
1121 | { | |
af4f74fa | 1122 | const struct name_to_bb *n1 = (const struct name_to_bb *)p1; |
1123 | const struct name_to_bb *n2 = (const struct name_to_bb *)p2; | |
e6d0e152 | 1124 | |
af4f74fa | 1125 | return n1->ssa_name == n2->ssa_name && n1->store == n2->store; |
e6d0e152 | 1126 | } |
1127 | ||
1128 | /* We see a the expression EXP in basic block BB. If it's an interesting | |
1129 | expression (an INDIRECT_REF through an SSA_NAME) possibly insert the | |
af4f74fa | 1130 | expression into the set NONTRAP or the hash table of seen expressions. |
1131 | STORE is true if this expression is on the LHS, otherwise it's on | |
1132 | the RHS. */ | |
e6d0e152 | 1133 | static void |
af4f74fa | 1134 | add_or_mark_expr (basic_block bb, tree exp, |
1135 | struct pointer_set_t *nontrap, bool store) | |
e6d0e152 | 1136 | { |
1137 | if (INDIRECT_REF_P (exp) | |
1138 | && TREE_CODE (TREE_OPERAND (exp, 0)) == SSA_NAME) | |
1139 | { | |
1140 | tree name = TREE_OPERAND (exp, 0); | |
1141 | struct name_to_bb map; | |
1142 | void **slot; | |
af4f74fa | 1143 | struct name_to_bb *n2bb; |
e6d0e152 | 1144 | basic_block found_bb = 0; |
1145 | ||
1146 | /* Try to find the last seen INDIRECT_REF through the same | |
1147 | SSA_NAME, which can trap. */ | |
1148 | map.ssa_name = name; | |
1149 | map.bb = 0; | |
af4f74fa | 1150 | map.store = store; |
e6d0e152 | 1151 | slot = htab_find_slot (seen_ssa_names, &map, INSERT); |
af4f74fa | 1152 | n2bb = (struct name_to_bb *) *slot; |
1153 | if (n2bb) | |
1154 | found_bb = n2bb->bb; | |
e6d0e152 | 1155 | |
1156 | /* If we've found a trapping INDIRECT_REF, _and_ it dominates EXP | |
1157 | (it's in a basic block on the path from us to the dominator root) | |
1158 | then we can't trap. */ | |
1159 | if (found_bb && found_bb->aux == (void *)1) | |
1160 | { | |
1161 | pointer_set_insert (nontrap, exp); | |
1162 | } | |
1163 | else | |
1164 | { | |
1165 | /* EXP might trap, so insert it into the hash table. */ | |
af4f74fa | 1166 | if (n2bb) |
e6d0e152 | 1167 | { |
af4f74fa | 1168 | n2bb->bb = bb; |
e6d0e152 | 1169 | } |
1170 | else | |
1171 | { | |
af4f74fa | 1172 | n2bb = XNEW (struct name_to_bb); |
1173 | n2bb->ssa_name = name; | |
1174 | n2bb->bb = bb; | |
1175 | n2bb->store = store; | |
1176 | *slot = n2bb; | |
e6d0e152 | 1177 | } |
1178 | } | |
1179 | } | |
1180 | } | |
1181 | ||
1182 | /* Called by walk_dominator_tree, when entering the block BB. */ | |
1183 | static void | |
1184 | nt_init_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb) | |
1185 | { | |
1186 | block_stmt_iterator bsi; | |
1187 | /* Mark this BB as being on the path to dominator root. */ | |
1188 | bb->aux = (void*)1; | |
1189 | ||
1190 | /* And walk the statements in order. */ | |
1191 | for (bsi = bsi_start (bb); !bsi_end_p (bsi); bsi_next (&bsi)) | |
1192 | { | |
1193 | tree stmt = bsi_stmt (bsi); | |
1194 | ||
1195 | if (TREE_CODE (stmt) == GIMPLE_MODIFY_STMT) | |
1196 | { | |
1197 | tree lhs = GIMPLE_STMT_OPERAND (stmt, 0); | |
1198 | tree rhs = GIMPLE_STMT_OPERAND (stmt, 1); | |
af4f74fa | 1199 | add_or_mark_expr (bb, rhs, nontrap_set, false); |
1200 | add_or_mark_expr (bb, lhs, nontrap_set, true); | |
e6d0e152 | 1201 | } |
1202 | } | |
1203 | } | |
1204 | ||
1205 | /* Called by walk_dominator_tree, when basic block BB is exited. */ | |
1206 | static void | |
1207 | nt_fini_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb) | |
1208 | { | |
1209 | /* This BB isn't on the path to dominator root anymore. */ | |
1210 | bb->aux = NULL; | |
1211 | } | |
1212 | ||
1213 | /* This is the entry point of gathering non trapping memory accesses. | |
1214 | It will do a dominator walk over the whole function, and it will | |
1215 | make use of the bb->aux pointers. It returns a set of trees | |
1216 | (the INDIRECT_REFs itself) which can't trap. */ | |
1217 | static struct pointer_set_t * | |
1218 | get_non_trapping (void) | |
1219 | { | |
1220 | struct pointer_set_t *nontrap; | |
1221 | struct dom_walk_data walk_data; | |
1222 | ||
1223 | nontrap = pointer_set_create (); | |
1224 | seen_ssa_names = htab_create (128, name_to_bb_hash, name_to_bb_eq, | |
1225 | free); | |
1226 | /* We're going to do a dominator walk, so ensure that we have | |
1227 | dominance information. */ | |
1228 | calculate_dominance_info (CDI_DOMINATORS); | |
1229 | ||
1230 | /* Setup callbacks for the generic dominator tree walker. */ | |
1231 | nontrap_set = nontrap; | |
1232 | walk_data.walk_stmts_backward = false; | |
1233 | walk_data.dom_direction = CDI_DOMINATORS; | |
1234 | walk_data.initialize_block_local_data = NULL; | |
1235 | walk_data.before_dom_children_before_stmts = nt_init_block; | |
1236 | walk_data.before_dom_children_walk_stmts = NULL; | |
1237 | walk_data.before_dom_children_after_stmts = NULL; | |
1238 | walk_data.after_dom_children_before_stmts = NULL; | |
1239 | walk_data.after_dom_children_walk_stmts = NULL; | |
1240 | walk_data.after_dom_children_after_stmts = nt_fini_block; | |
1241 | walk_data.global_data = NULL; | |
1242 | walk_data.block_local_data_size = 0; | |
1243 | walk_data.interesting_blocks = NULL; | |
1244 | ||
1245 | init_walk_dominator_tree (&walk_data); | |
1246 | walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); | |
1247 | fini_walk_dominator_tree (&walk_data); | |
1248 | htab_delete (seen_ssa_names); | |
1249 | ||
1250 | return nontrap; | |
1251 | } | |
1252 | ||
1253 | /* Do the main work of conditional store replacement. We already know | |
1254 | that the recognized pattern looks like so: | |
1255 | ||
1256 | split: | |
1257 | if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1) | |
1258 | MIDDLE_BB: | |
1259 | something | |
1260 | fallthrough (edge E0) | |
1261 | JOIN_BB: | |
1262 | some more | |
1263 | ||
1264 | We check that MIDDLE_BB contains only one store, that that store | |
1265 | doesn't trap (not via NOTRAP, but via checking if an access to the same | |
1266 | memory location dominates us) and that the store has a "simple" RHS. */ | |
1267 | ||
1268 | static bool | |
1269 | cond_store_replacement (basic_block middle_bb, basic_block join_bb, | |
1270 | edge e0, edge e1, struct pointer_set_t *nontrap) | |
1271 | { | |
1272 | tree assign = last_and_only_stmt (middle_bb); | |
1273 | tree lhs, rhs, newexpr, name; | |
1274 | tree newphi; | |
1275 | block_stmt_iterator bsi; | |
1276 | ||
1277 | /* Check if middle_bb contains of only one store. */ | |
1278 | if (!assign | |
1279 | || TREE_CODE (assign) != GIMPLE_MODIFY_STMT) | |
1280 | return false; | |
1281 | ||
1282 | lhs = GIMPLE_STMT_OPERAND (assign, 0); | |
1283 | if (!INDIRECT_REF_P (lhs)) | |
1284 | return false; | |
1285 | rhs = GIMPLE_STMT_OPERAND (assign, 1); | |
1286 | if (TREE_CODE (rhs) != SSA_NAME && !is_gimple_min_invariant (rhs)) | |
1287 | return false; | |
1288 | /* Prove that we can move the store down. We could also check | |
1289 | TREE_THIS_NOTRAP here, but in that case we also could move stores, | |
1290 | whose value is not available readily, which we want to avoid. */ | |
1291 | if (!pointer_set_contains (nontrap, lhs)) | |
1292 | return false; | |
1293 | ||
1294 | /* Now we've checked the constraints, so do the transformation: | |
1295 | 1) Remove the single store. */ | |
1296 | mark_symbols_for_renaming (assign); | |
1297 | bsi = bsi_for_stmt (assign); | |
1298 | bsi_remove (&bsi, true); | |
1299 | ||
1300 | /* 2) Create a temporary where we can store the old content | |
1301 | of the memory touched by the store, if we need to. */ | |
1302 | if (!condstoretemp || TREE_TYPE (lhs) != TREE_TYPE (condstoretemp)) | |
1303 | { | |
1304 | condstoretemp = create_tmp_var (TREE_TYPE (lhs), "cstore"); | |
1305 | get_var_ann (condstoretemp); | |
0aa073df | 1306 | if (TREE_CODE (TREE_TYPE (lhs)) == COMPLEX_TYPE |
1307 | || TREE_CODE (TREE_TYPE (lhs)) == VECTOR_TYPE) | |
1308 | DECL_GIMPLE_REG_P (condstoretemp) = 1; | |
e6d0e152 | 1309 | } |
1310 | add_referenced_var (condstoretemp); | |
1311 | ||
1312 | /* 3) Insert a load from the memory of the store to the temporary | |
1313 | on the edge which did not contain the store. */ | |
1314 | lhs = unshare_expr (lhs); | |
1315 | newexpr = build_gimple_modify_stmt (condstoretemp, lhs); | |
1316 | name = make_ssa_name (condstoretemp, newexpr); | |
1317 | GIMPLE_STMT_OPERAND (newexpr, 0) = name; | |
1318 | mark_symbols_for_renaming (newexpr); | |
1319 | bsi_insert_on_edge (e1, newexpr); | |
1320 | ||
1321 | /* 4) Create a PHI node at the join block, with one argument | |
1322 | holding the old RHS, and the other holding the temporary | |
1323 | where we stored the old memory contents. */ | |
1324 | newphi = create_phi_node (condstoretemp, join_bb); | |
1325 | add_phi_arg (newphi, rhs, e0); | |
1326 | add_phi_arg (newphi, name, e1); | |
1327 | ||
1328 | lhs = unshare_expr (lhs); | |
1329 | newexpr = build_gimple_modify_stmt (lhs, PHI_RESULT (newphi)); | |
1330 | mark_symbols_for_renaming (newexpr); | |
1331 | ||
1332 | /* 5) Insert that PHI node. */ | |
1333 | bsi = bsi_start (join_bb); | |
1334 | while (!bsi_end_p (bsi) && TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR) | |
1335 | bsi_next (&bsi); | |
1336 | if (bsi_end_p (bsi)) | |
1337 | { | |
1338 | bsi = bsi_last (join_bb); | |
1339 | bsi_insert_after (&bsi, newexpr, BSI_NEW_STMT); | |
1340 | } | |
1341 | else | |
1342 | bsi_insert_before (&bsi, newexpr, BSI_NEW_STMT); | |
1343 | ||
1344 | return true; | |
1345 | } | |
4ee9c684 | 1346 | |
1347 | /* Always do these optimizations if we have SSA | |
20e5647c | 1348 | trees to work on. */ |
4ee9c684 | 1349 | static bool |
1350 | gate_phiopt (void) | |
1351 | { | |
1352 | return 1; | |
1353 | } | |
20e5647c | 1354 | |
4ee9c684 | 1355 | struct tree_opt_pass pass_phiopt = |
1356 | { | |
1357 | "phiopt", /* name */ | |
1358 | gate_phiopt, /* gate */ | |
1359 | tree_ssa_phiopt, /* execute */ | |
1360 | NULL, /* sub */ | |
1361 | NULL, /* next */ | |
1362 | 0, /* static_pass_number */ | |
1363 | TV_TREE_PHIOPT, /* tv_id */ | |
f45a1ca1 | 1364 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
4ee9c684 | 1365 | 0, /* properties_provided */ |
1366 | 0, /* properties_destroyed */ | |
1367 | 0, /* todo_flags_start */ | |
1e4b21e3 | 1368 | TODO_dump_func |
88dbf20f | 1369 | | TODO_ggc_collect |
1370 | | TODO_verify_ssa | |
88dbf20f | 1371 | | TODO_verify_flow |
1372 | | TODO_verify_stmts, /* todo_flags_finish */ | |
0f9005dd | 1373 | 0 /* letter */ |
4ee9c684 | 1374 | }; |
e6d0e152 | 1375 | |
1376 | static bool | |
1377 | gate_cselim (void) | |
1378 | { | |
1379 | return flag_tree_cselim; | |
1380 | } | |
1381 | ||
1382 | struct tree_opt_pass pass_cselim = | |
1383 | { | |
1384 | "cselim", /* name */ | |
1385 | gate_cselim, /* gate */ | |
1386 | tree_ssa_cs_elim, /* execute */ | |
1387 | NULL, /* sub */ | |
1388 | NULL, /* next */ | |
1389 | 0, /* static_pass_number */ | |
1390 | TV_TREE_PHIOPT, /* tv_id */ | |
1391 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ | |
1392 | 0, /* properties_provided */ | |
1393 | 0, /* properties_destroyed */ | |
1394 | 0, /* todo_flags_start */ | |
1395 | TODO_dump_func | |
1396 | | TODO_ggc_collect | |
1397 | | TODO_verify_ssa | |
1398 | | TODO_verify_flow | |
1399 | | TODO_verify_stmts, /* todo_flags_finish */ | |
1400 | 0 /* letter */ | |
1401 | }; |