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4ee9c684 | 1 | /* Optimization of PHI nodes by converting them into straightline code. |
20e5647c | 2 | Copyright (C) 2004, 2005 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 | |
8 | Free Software Foundation; either version 2, or (at your option) any | |
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 |
17 | along with GCC; see the file COPYING. If not, write to the Free | |
67ce556b | 18 | Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA |
19 | 02110-1301, USA. */ | |
4ee9c684 | 20 | |
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
24 | #include "tm.h" | |
4ee9c684 | 25 | #include "ggc.h" |
26 | #include "tree.h" | |
27 | #include "rtl.h" | |
0beac6fc | 28 | #include "flags.h" |
4ee9c684 | 29 | #include "tm_p.h" |
30 | #include "basic-block.h" | |
31 | #include "timevar.h" | |
32 | #include "diagnostic.h" | |
33 | #include "tree-flow.h" | |
34 | #include "tree-pass.h" | |
35 | #include "tree-dump.h" | |
36 | #include "langhooks.h" | |
37 | ||
38 | static void tree_ssa_phiopt (void); | |
a4844041 | 39 | static bool conditional_replacement (basic_block, basic_block, |
33784d89 | 40 | edge, edge, tree, tree, tree); |
a4844041 | 41 | static bool value_replacement (basic_block, basic_block, |
33784d89 | 42 | edge, edge, tree, tree, tree); |
a4844041 | 43 | static bool minmax_replacement (basic_block, basic_block, |
194899bf | 44 | edge, edge, tree, tree, tree); |
a4844041 | 45 | static bool abs_replacement (basic_block, basic_block, |
33784d89 | 46 | edge, edge, tree, tree, tree); |
a4844041 | 47 | static void replace_phi_edge_with_variable (basic_block, edge, tree, tree); |
194899bf | 48 | static basic_block *blocks_in_phiopt_order (void); |
902929aa | 49 | |
caac37c2 | 50 | /* This pass tries to replaces an if-then-else block with an |
51 | assignment. We have four kinds of transformations. Some of these | |
52 | transformations are also performed by the ifcvt RTL optimizer. | |
53 | ||
54 | Conditional Replacement | |
55 | ----------------------- | |
56 | ||
30c5ffd2 | 57 | This transformation, implemented in conditional_replacement, |
caac37c2 | 58 | replaces |
4ee9c684 | 59 | |
60 | bb0: | |
61 | if (cond) goto bb2; else goto bb1; | |
62 | bb1: | |
63 | bb2: | |
caac37c2 | 64 | x = PHI <0 (bb1), 1 (bb0), ...>; |
4ee9c684 | 65 | |
caac37c2 | 66 | with |
20e5647c | 67 | |
2ab0a163 | 68 | bb0: |
caac37c2 | 69 | x' = cond; |
70 | goto bb2; | |
2ab0a163 | 71 | bb2: |
caac37c2 | 72 | x = PHI <x' (bb0), ...>; |
4ee9c684 | 73 | |
caac37c2 | 74 | We remove bb1 as it becomes unreachable. This occurs often due to |
75 | gimplification of conditionals. | |
20e5647c | 76 | |
caac37c2 | 77 | Value Replacement |
78 | ----------------- | |
79 | ||
80 | This transformation, implemented in value_replacement, replaces | |
0beac6fc | 81 | |
82 | bb0: | |
caac37c2 | 83 | if (a != b) goto bb2; else goto bb1; |
0beac6fc | 84 | bb1: |
85 | bb2: | |
caac37c2 | 86 | x = PHI <a (bb1), b (bb0), ...>; |
0beac6fc | 87 | |
caac37c2 | 88 | with |
0beac6fc | 89 | |
90 | bb0: | |
0beac6fc | 91 | bb2: |
caac37c2 | 92 | x = PHI <b (bb0), ...>; |
93 | ||
94 | This opportunity can sometimes occur as a result of other | |
95 | optimizations. | |
0beac6fc | 96 | |
caac37c2 | 97 | ABS Replacement |
98 | --------------- | |
70512b93 | 99 | |
caac37c2 | 100 | This transformation, implemented in abs_replacement, replaces |
70512b93 | 101 | |
102 | bb0: | |
caac37c2 | 103 | if (a >= 0) goto bb2; else goto bb1; |
70512b93 | 104 | bb1: |
caac37c2 | 105 | x = -a; |
70512b93 | 106 | bb2: |
caac37c2 | 107 | x = PHI <x (bb1), a (bb0), ...>; |
70512b93 | 108 | |
caac37c2 | 109 | with |
70512b93 | 110 | |
111 | bb0: | |
caac37c2 | 112 | x' = ABS_EXPR< a >; |
70512b93 | 113 | bb2: |
caac37c2 | 114 | x = PHI <x' (bb0), ...>; |
115 | ||
116 | MIN/MAX Replacement | |
117 | ------------------- | |
70512b93 | 118 | |
caac37c2 | 119 | This transformation, minmax_replacement replaces |
194899bf | 120 | |
121 | bb0: | |
caac37c2 | 122 | if (a <= b) goto bb2; else goto bb1; |
194899bf | 123 | bb1: |
194899bf | 124 | bb2: |
caac37c2 | 125 | x = PHI <b (bb1), a (bb0), ...>; |
194899bf | 126 | |
caac37c2 | 127 | with |
194899bf | 128 | |
caac37c2 | 129 | bb0: |
130 | x' = MIN_EXPR (a, b) | |
131 | bb2: | |
132 | x = PHI <x' (bb0), ...>; | |
194899bf | 133 | |
30c5ffd2 | 134 | A similar transformation is done for MAX_EXPR. */ |
70512b93 | 135 | |
4ee9c684 | 136 | static void |
137 | tree_ssa_phiopt (void) | |
138 | { | |
139 | basic_block bb; | |
194899bf | 140 | basic_block *bb_order; |
141 | unsigned n, i; | |
142 | ||
143 | /* Search every basic block for COND_EXPR we may be able to optimize. | |
144 | ||
145 | We walk the blocks in order that guarantees that a block with | |
146 | a single predecessor is processed before the predecessor. | |
147 | This ensures that we collapse inner ifs before visiting the | |
148 | outer ones, and also that we do not try to visit a removed | |
149 | block. */ | |
150 | bb_order = blocks_in_phiopt_order (); | |
151 | n = n_basic_blocks; | |
4ee9c684 | 152 | |
194899bf | 153 | for (i = 0; i < n; i++) |
4ee9c684 | 154 | { |
33784d89 | 155 | tree cond_expr; |
156 | tree phi; | |
157 | basic_block bb1, bb2; | |
158 | edge e1, e2; | |
194899bf | 159 | tree arg0, arg1; |
160 | ||
161 | bb = bb_order[i]; | |
20e5647c | 162 | |
33784d89 | 163 | cond_expr = last_stmt (bb); |
20e5647c | 164 | /* Check to see if the last statement is a COND_EXPR. */ |
33784d89 | 165 | if (!cond_expr |
166 | || TREE_CODE (cond_expr) != COND_EXPR) | |
167 | continue; | |
20e5647c | 168 | |
33784d89 | 169 | e1 = EDGE_SUCC (bb, 0); |
170 | bb1 = e1->dest; | |
171 | e2 = EDGE_SUCC (bb, 1); | |
172 | bb2 = e2->dest; | |
20e5647c | 173 | |
33784d89 | 174 | /* We cannot do the optimization on abnormal edges. */ |
175 | if ((e1->flags & EDGE_ABNORMAL) != 0 | |
176 | || (e2->flags & EDGE_ABNORMAL) != 0) | |
177 | continue; | |
20e5647c | 178 | |
33784d89 | 179 | /* If either bb1's succ or bb2 or bb2's succ is non NULL. */ |
ea091dfd | 180 | if (EDGE_COUNT (bb1->succs) == 0 |
33784d89 | 181 | || bb2 == NULL |
ea091dfd | 182 | || EDGE_COUNT (bb2->succs) == 0) |
33784d89 | 183 | continue; |
20e5647c | 184 | |
33784d89 | 185 | /* Find the bb which is the fall through to the other. */ |
186 | if (EDGE_SUCC (bb1, 0)->dest == bb2) | |
187 | ; | |
188 | else if (EDGE_SUCC (bb2, 0)->dest == bb1) | |
189 | { | |
190 | basic_block bb_tmp = bb1; | |
191 | edge e_tmp = e1; | |
192 | bb1 = bb2; | |
193 | bb2 = bb_tmp; | |
194 | e1 = e2; | |
195 | e2 = e_tmp; | |
196 | } | |
197 | else | |
198 | continue; | |
20e5647c | 199 | |
33784d89 | 200 | e1 = EDGE_SUCC (bb1, 0); |
20e5647c | 201 | |
33784d89 | 202 | /* Make sure that bb1 is just a fall through. */ |
db5ba14c | 203 | if (!single_succ_p (bb1) |
33784d89 | 204 | || (e1->flags & EDGE_FALLTHRU) == 0) |
205 | continue; | |
20e5647c | 206 | |
3472707f | 207 | /* Also make sure that bb1 only have one predecessor and that it |
208 | is bb. */ | |
ea091dfd | 209 | if (!single_pred_p (bb1) |
210 | || single_pred (bb1) != bb) | |
33784d89 | 211 | continue; |
20e5647c | 212 | |
33784d89 | 213 | phi = phi_nodes (bb2); |
4ee9c684 | 214 | |
33784d89 | 215 | /* Check to make sure that there is only one PHI node. |
216 | TODO: we could do it with more than one iff the other PHI nodes | |
217 | have the same elements for these two edges. */ | |
194899bf | 218 | if (!phi || PHI_CHAIN (phi) != NULL) |
219 | continue; | |
20e5647c | 220 | |
194899bf | 221 | arg0 = PHI_ARG_DEF_TREE (phi, e1->dest_idx); |
222 | arg1 = PHI_ARG_DEF_TREE (phi, e2->dest_idx); | |
20e5647c | 223 | |
3472707f | 224 | /* Something is wrong if we cannot find the arguments in the PHI |
194899bf | 225 | node. */ |
226 | gcc_assert (arg0 != NULL && arg1 != NULL); | |
20e5647c | 227 | |
194899bf | 228 | /* Do the replacement of conditional if it can be done. */ |
a4844041 | 229 | if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
194899bf | 230 | ; |
a4844041 | 231 | else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
194899bf | 232 | ; |
a4844041 | 233 | else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) |
194899bf | 234 | ; |
235 | else | |
a4844041 | 236 | minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1); |
194899bf | 237 | } |
238 | ||
239 | free (bb_order); | |
240 | } | |
241 | ||
242 | /* Returns the list of basic blocks in the function in an order that guarantees | |
243 | that if a block X has just a single predecessor Y, then Y is after X in the | |
244 | ordering. */ | |
245 | ||
246 | static basic_block * | |
247 | blocks_in_phiopt_order (void) | |
248 | { | |
249 | basic_block x, y; | |
250 | basic_block *order = xmalloc (sizeof (basic_block) * n_basic_blocks); | |
251 | unsigned n = n_basic_blocks, np, i; | |
252 | sbitmap visited = sbitmap_alloc (last_basic_block + 2); | |
253 | ||
254 | #define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index + 2)) | |
255 | #define VISITED_P(BB) (TEST_BIT (visited, (BB)->index + 2)) | |
256 | ||
257 | sbitmap_zero (visited); | |
258 | ||
259 | MARK_VISITED (ENTRY_BLOCK_PTR); | |
260 | FOR_EACH_BB (x) | |
261 | { | |
262 | if (VISITED_P (x)) | |
263 | continue; | |
264 | ||
265 | /* Walk the predecessors of x as long as they have precisely one | |
266 | predecessor and add them to the list, so that they get stored | |
267 | after x. */ | |
268 | for (y = x, np = 1; | |
269 | single_pred_p (y) && !VISITED_P (single_pred (y)); | |
270 | y = single_pred (y)) | |
271 | np++; | |
272 | for (y = x, i = n - np; | |
273 | single_pred_p (y) && !VISITED_P (single_pred (y)); | |
274 | y = single_pred (y), i++) | |
275 | { | |
276 | order[i] = y; | |
277 | MARK_VISITED (y); | |
2ab0a163 | 278 | } |
194899bf | 279 | order[i] = y; |
280 | MARK_VISITED (y); | |
281 | ||
282 | gcc_assert (i == n - 1); | |
283 | n -= np; | |
4ee9c684 | 284 | } |
194899bf | 285 | |
286 | sbitmap_free (visited); | |
287 | gcc_assert (n == 0); | |
288 | return order; | |
289 | ||
290 | #undef MARK_VISITED | |
291 | #undef VISITED_P | |
4ee9c684 | 292 | } |
293 | ||
70512b93 | 294 | /* Return TRUE if block BB has no executable statements, otherwise return |
295 | FALSE. */ | |
c91e8223 | 296 | bool |
70512b93 | 297 | empty_block_p (basic_block bb) |
298 | { | |
299 | block_stmt_iterator bsi; | |
300 | ||
301 | /* BB must have no executable statements. */ | |
302 | bsi = bsi_start (bb); | |
303 | while (!bsi_end_p (bsi) | |
304 | && (TREE_CODE (bsi_stmt (bsi)) == LABEL_EXPR | |
305 | || IS_EMPTY_STMT (bsi_stmt (bsi)))) | |
306 | bsi_next (&bsi); | |
20e5647c | 307 | |
70512b93 | 308 | if (!bsi_end_p (bsi)) |
309 | return false; | |
310 | ||
311 | return true; | |
312 | } | |
313 | ||
fccee353 | 314 | /* Replace PHI node element whose edge is E in block BB with variable NEW. |
33784d89 | 315 | Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK |
902929aa | 316 | is known to have two edges, one of which must reach BB). */ |
317 | ||
318 | static void | |
a4844041 | 319 | replace_phi_edge_with_variable (basic_block cond_block, |
33784d89 | 320 | edge e, tree phi, tree new) |
902929aa | 321 | { |
a4844041 | 322 | basic_block bb = bb_for_stmt (phi); |
0e1a77e1 | 323 | basic_block block_to_remove; |
33784d89 | 324 | block_stmt_iterator bsi; |
325 | ||
20e5647c | 326 | /* Change the PHI argument to new. */ |
22aa74c4 | 327 | SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new); |
0e1a77e1 | 328 | |
0e1a77e1 | 329 | /* Remove the empty basic block. */ |
cd665a06 | 330 | if (EDGE_SUCC (cond_block, 0)->dest == bb) |
902929aa | 331 | { |
cd665a06 | 332 | EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU; |
333 | EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); | |
0e1a77e1 | 334 | |
cd665a06 | 335 | block_to_remove = EDGE_SUCC (cond_block, 1)->dest; |
902929aa | 336 | } |
337 | else | |
338 | { | |
cd665a06 | 339 | EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU; |
340 | EDGE_SUCC (cond_block, 1)->flags | |
902929aa | 341 | &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); |
0e1a77e1 | 342 | |
cd665a06 | 343 | block_to_remove = EDGE_SUCC (cond_block, 0)->dest; |
902929aa | 344 | } |
0e1a77e1 | 345 | delete_basic_block (block_to_remove); |
20e5647c | 346 | |
902929aa | 347 | /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ |
348 | bsi = bsi_last (cond_block); | |
349 | bsi_remove (&bsi); | |
20e5647c | 350 | |
902929aa | 351 | if (dump_file && (dump_flags & TDF_DETAILS)) |
352 | fprintf (dump_file, | |
353 | "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n", | |
354 | cond_block->index, | |
355 | bb->index); | |
356 | } | |
357 | ||
358 | /* The function conditional_replacement does the main work of doing the | |
359 | conditional replacement. Return true if the replacement is done. | |
360 | Otherwise return false. | |
361 | BB is the basic block where the replacement is going to be done on. ARG0 | |
dac49aa5 | 362 | is argument 0 from PHI. Likewise for ARG1. */ |
902929aa | 363 | |
364 | static bool | |
33784d89 | 365 | conditional_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 366 | edge e0, edge e1, tree phi, |
33784d89 | 367 | tree arg0, tree arg1) |
902929aa | 368 | { |
369 | tree result; | |
370 | tree old_result = NULL; | |
902929aa | 371 | tree new, cond; |
372 | block_stmt_iterator bsi; | |
373 | edge true_edge, false_edge; | |
374 | tree new_var = NULL; | |
33784d89 | 375 | tree new_var1; |
902929aa | 376 | |
377 | /* The PHI arguments have the constants 0 and 1, then convert | |
378 | it to the conditional. */ | |
379 | if ((integer_zerop (arg0) && integer_onep (arg1)) | |
380 | || (integer_zerop (arg1) && integer_onep (arg0))) | |
381 | ; | |
382 | else | |
383 | return false; | |
20e5647c | 384 | |
33784d89 | 385 | if (!empty_block_p (middle_bb)) |
902929aa | 386 | return false; |
20e5647c | 387 | |
4ee9c684 | 388 | /* If the condition is not a naked SSA_NAME and its type does not |
2ab0a163 | 389 | match the type of the result, then we have to create a new |
390 | variable to optimize this case as it would likely create | |
391 | non-gimple code when the condition was converted to the | |
392 | result's type. */ | |
33784d89 | 393 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
4ee9c684 | 394 | result = PHI_RESULT (phi); |
395 | if (TREE_CODE (cond) != SSA_NAME | |
396 | && !lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result))) | |
ae5a4794 | 397 | { |
398 | new_var = make_rename_temp (TREE_TYPE (cond), NULL); | |
399 | old_result = cond; | |
400 | cond = new_var; | |
401 | } | |
20e5647c | 402 | |
4ee9c684 | 403 | /* If the condition was a naked SSA_NAME and the type is not the |
2ab0a163 | 404 | same as the type of the result, then convert the type of the |
405 | condition. */ | |
4ee9c684 | 406 | if (!lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result))) |
407 | cond = fold_convert (TREE_TYPE (result), cond); | |
20e5647c | 408 | |
4ee9c684 | 409 | /* We need to know which is the true edge and which is the false |
2ab0a163 | 410 | edge so that we know when to invert the condition below. */ |
33784d89 | 411 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
20e5647c | 412 | |
1fa68a1f | 413 | /* Insert our new statement at the end of conditional block before the |
33784d89 | 414 | COND_EXPR. */ |
415 | bsi = bsi_last (cond_bb); | |
416 | bsi_insert_before (&bsi, build_empty_stmt (), BSI_NEW_STMT); | |
20e5647c | 417 | |
ae5a4794 | 418 | if (old_result) |
419 | { | |
420 | tree new1; | |
ce45a448 | 421 | if (!COMPARISON_CLASS_P (old_result)) |
2ab0a163 | 422 | return false; |
20e5647c | 423 | |
194899bf | 424 | new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result), |
425 | TREE_OPERAND (old_result, 0), | |
426 | TREE_OPERAND (old_result, 1)); | |
20e5647c | 427 | |
194899bf | 428 | new1 = build2 (MODIFY_EXPR, TREE_TYPE (old_result), new_var, new1); |
ae5a4794 | 429 | bsi_insert_after (&bsi, new1, BSI_NEW_STMT); |
430 | } | |
20e5647c | 431 | |
33784d89 | 432 | new_var1 = duplicate_ssa_name (PHI_RESULT (phi), NULL); |
20e5647c | 433 | |
434 | ||
4ee9c684 | 435 | /* At this point we know we have a COND_EXPR with two successors. |
2ab0a163 | 436 | One successor is BB, the other successor is an empty block which |
437 | falls through into BB. | |
20e5647c | 438 | |
2ab0a163 | 439 | There is a single PHI node at the join point (BB) and its arguments |
440 | are constants (0, 1). | |
20e5647c | 441 | |
2ab0a163 | 442 | So, given the condition COND, and the two PHI arguments, we can |
20e5647c | 443 | rewrite this PHI into non-branching code: |
444 | ||
2ab0a163 | 445 | dest = (COND) or dest = COND' |
20e5647c | 446 | |
2ab0a163 | 447 | We use the condition as-is if the argument associated with the |
448 | true edge has the value one or the argument associated with the | |
449 | false edge as the value zero. Note that those conditions are not | |
450 | the same since only one of the outgoing edges from the COND_EXPR | |
451 | will directly reach BB and thus be associated with an argument. */ | |
33784d89 | 452 | if ((e0 == true_edge && integer_onep (arg0)) |
453 | || (e0 == false_edge && integer_zerop (arg0)) | |
454 | || (e1 == true_edge && integer_onep (arg1)) | |
455 | || (e1 == false_edge && integer_zerop (arg1))) | |
4ee9c684 | 456 | { |
194899bf | 457 | new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond); |
4ee9c684 | 458 | } |
459 | else | |
460 | { | |
ae5a4794 | 461 | tree cond1 = invert_truthvalue (cond); |
20e5647c | 462 | |
ae5a4794 | 463 | cond = cond1; |
464 | /* If what we get back is a conditional expression, there is no | |
0beac6fc | 465 | way that it can be gimple. */ |
ae5a4794 | 466 | if (TREE_CODE (cond) == COND_EXPR) |
33784d89 | 467 | { |
468 | release_ssa_name (new_var1); | |
20e5647c | 469 | return false; |
33784d89 | 470 | } |
ae5a4794 | 471 | |
472 | /* If what we get back is not gimple try to create it as gimple by | |
dac49aa5 | 473 | using a temporary variable. */ |
4ee9c684 | 474 | if (is_gimple_cast (cond) |
475 | && !is_gimple_val (TREE_OPERAND (cond, 0))) | |
2ab0a163 | 476 | { |
477 | tree temp = TREE_OPERAND (cond, 0); | |
478 | tree new_var_1 = make_rename_temp (TREE_TYPE (temp), NULL); | |
194899bf | 479 | new = build2 (MODIFY_EXPR, TREE_TYPE (new_var_1), new_var_1, temp); |
2ab0a163 | 480 | bsi_insert_after (&bsi, new, BSI_NEW_STMT); |
481 | cond = fold_convert (TREE_TYPE (result), new_var_1); | |
482 | } | |
20e5647c | 483 | |
4ee9c684 | 484 | if (TREE_CODE (cond) == TRUTH_NOT_EXPR |
2ab0a163 | 485 | && !is_gimple_val (TREE_OPERAND (cond, 0))) |
33784d89 | 486 | { |
487 | release_ssa_name (new_var1); | |
488 | return false; | |
489 | } | |
4ee9c684 | 490 | |
194899bf | 491 | new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond); |
4ee9c684 | 492 | } |
20e5647c | 493 | |
33784d89 | 494 | bsi_insert_after (&bsi, new, BSI_NEW_STMT); |
20e5647c | 495 | |
33784d89 | 496 | SSA_NAME_DEF_STMT (new_var1) = new; |
20e5647c | 497 | |
a4844041 | 498 | replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1); |
902929aa | 499 | |
4ee9c684 | 500 | /* Note that we optimized this PHI. */ |
501 | return true; | |
502 | } | |
503 | ||
0beac6fc | 504 | /* The function value_replacement does the main work of doing the value |
505 | replacement. Return true if the replacement is done. Otherwise return | |
506 | false. | |
507 | BB is the basic block where the replacement is going to be done on. ARG0 | |
dac49aa5 | 508 | is argument 0 from the PHI. Likewise for ARG1. */ |
0beac6fc | 509 | |
510 | static bool | |
33784d89 | 511 | value_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 512 | edge e0, edge e1, tree phi, |
33784d89 | 513 | tree arg0, tree arg1) |
0beac6fc | 514 | { |
33784d89 | 515 | tree cond; |
0beac6fc | 516 | edge true_edge, false_edge; |
517 | ||
518 | /* If the type says honor signed zeros we cannot do this | |
dac49aa5 | 519 | optimization. */ |
0beac6fc | 520 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) |
521 | return false; | |
522 | ||
33784d89 | 523 | if (!empty_block_p (middle_bb)) |
0beac6fc | 524 | return false; |
525 | ||
33784d89 | 526 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
0beac6fc | 527 | |
528 | /* This transformation is only valid for equality comparisons. */ | |
529 | if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR) | |
530 | return false; | |
531 | ||
532 | /* We need to know which is the true edge and which is the false | |
533 | edge so that we know if have abs or negative abs. */ | |
33784d89 | 534 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
0beac6fc | 535 | |
536 | /* At this point we know we have a COND_EXPR with two successors. | |
537 | One successor is BB, the other successor is an empty block which | |
538 | falls through into BB. | |
539 | ||
540 | The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR. | |
541 | ||
542 | There is a single PHI node at the join point (BB) with two arguments. | |
543 | ||
544 | We now need to verify that the two arguments in the PHI node match | |
545 | the two arguments to the equality comparison. */ | |
20e5647c | 546 | |
5373158f | 547 | if ((operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 0)) |
548 | && operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 1))) | |
549 | || (operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 0)) | |
550 | && operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 1)))) | |
0beac6fc | 551 | { |
552 | edge e; | |
553 | tree arg; | |
554 | ||
50737d20 | 555 | /* For NE_EXPR, we want to build an assignment result = arg where |
556 | arg is the PHI argument associated with the true edge. For | |
557 | EQ_EXPR we want the PHI argument associated with the false edge. */ | |
0beac6fc | 558 | e = (TREE_CODE (cond) == NE_EXPR ? true_edge : false_edge); |
50737d20 | 559 | |
560 | /* Unfortunately, E may not reach BB (it may instead have gone to | |
561 | OTHER_BLOCK). If that is the case, then we want the single outgoing | |
562 | edge from OTHER_BLOCK which reaches BB and represents the desired | |
563 | path from COND_BLOCK. */ | |
33784d89 | 564 | if (e->dest == middle_bb) |
ea091dfd | 565 | e = single_succ_edge (e->dest); |
50737d20 | 566 | |
567 | /* Now we know the incoming edge to BB that has the argument for the | |
568 | RHS of our new assignment statement. */ | |
33784d89 | 569 | if (e0 == e) |
0beac6fc | 570 | arg = arg0; |
571 | else | |
572 | arg = arg1; | |
573 | ||
a4844041 | 574 | replace_phi_edge_with_variable (cond_bb, e1, phi, arg); |
0beac6fc | 575 | |
576 | /* Note that we optimized this PHI. */ | |
577 | return true; | |
578 | } | |
579 | return false; | |
580 | } | |
581 | ||
194899bf | 582 | /* The function minmax_replacement does the main work of doing the minmax |
583 | replacement. Return true if the replacement is done. Otherwise return | |
584 | false. | |
585 | BB is the basic block where the replacement is going to be done on. ARG0 | |
586 | is argument 0 from the PHI. Likewise for ARG1. */ | |
587 | ||
588 | static bool | |
589 | minmax_replacement (basic_block cond_bb, basic_block middle_bb, | |
a4844041 | 590 | edge e0, edge e1, tree phi, |
194899bf | 591 | tree arg0, tree arg1) |
592 | { | |
593 | tree result, type; | |
594 | tree cond, new; | |
595 | edge true_edge, false_edge; | |
596 | enum tree_code cmp, minmax, ass_code; | |
597 | tree smaller, larger, arg_true, arg_false; | |
598 | block_stmt_iterator bsi, bsi_from; | |
599 | ||
600 | type = TREE_TYPE (PHI_RESULT (phi)); | |
601 | ||
602 | /* The optimization may be unsafe due to NaNs. */ | |
603 | if (HONOR_NANS (TYPE_MODE (type))) | |
604 | return false; | |
605 | ||
606 | cond = COND_EXPR_COND (last_stmt (cond_bb)); | |
607 | cmp = TREE_CODE (cond); | |
608 | result = PHI_RESULT (phi); | |
609 | ||
610 | /* This transformation is only valid for order comparisons. Record which | |
611 | operand is smaller/larger if the result of the comparison is true. */ | |
612 | if (cmp == LT_EXPR || cmp == LE_EXPR) | |
613 | { | |
614 | smaller = TREE_OPERAND (cond, 0); | |
615 | larger = TREE_OPERAND (cond, 1); | |
616 | } | |
617 | else if (cmp == GT_EXPR || cmp == GE_EXPR) | |
618 | { | |
619 | smaller = TREE_OPERAND (cond, 1); | |
620 | larger = TREE_OPERAND (cond, 0); | |
621 | } | |
622 | else | |
623 | return false; | |
624 | ||
625 | /* We need to know which is the true edge and which is the false | |
626 | edge so that we know if have abs or negative abs. */ | |
627 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); | |
628 | ||
629 | /* Forward the edges over the middle basic block. */ | |
630 | if (true_edge->dest == middle_bb) | |
631 | true_edge = EDGE_SUCC (true_edge->dest, 0); | |
632 | if (false_edge->dest == middle_bb) | |
633 | false_edge = EDGE_SUCC (false_edge->dest, 0); | |
634 | ||
635 | if (true_edge == e0) | |
636 | { | |
637 | gcc_assert (false_edge == e1); | |
638 | arg_true = arg0; | |
639 | arg_false = arg1; | |
640 | } | |
641 | else | |
642 | { | |
643 | gcc_assert (false_edge == e0); | |
644 | gcc_assert (true_edge == e1); | |
645 | arg_true = arg1; | |
646 | arg_false = arg0; | |
647 | } | |
648 | ||
649 | if (empty_block_p (middle_bb)) | |
650 | { | |
651 | if (operand_equal_for_phi_arg_p (arg_true, smaller) | |
652 | && operand_equal_for_phi_arg_p (arg_false, larger)) | |
653 | { | |
654 | /* Case | |
655 | ||
656 | if (smaller < larger) | |
657 | rslt = smaller; | |
658 | else | |
659 | rslt = larger; */ | |
660 | minmax = MIN_EXPR; | |
661 | } | |
662 | else if (operand_equal_for_phi_arg_p (arg_false, smaller) | |
663 | && operand_equal_for_phi_arg_p (arg_true, larger)) | |
664 | minmax = MAX_EXPR; | |
665 | else | |
666 | return false; | |
667 | } | |
668 | else | |
669 | { | |
670 | /* Recognize the following case, assuming d <= u: | |
671 | ||
672 | if (a <= u) | |
673 | b = MAX (a, d); | |
674 | x = PHI <b, u> | |
675 | ||
676 | This is equivalent to | |
677 | ||
678 | b = MAX (a, d); | |
679 | x = MIN (b, u); */ | |
680 | ||
681 | tree assign = last_and_only_stmt (middle_bb); | |
682 | tree lhs, rhs, op0, op1, bound; | |
683 | ||
684 | if (!assign | |
685 | || TREE_CODE (assign) != MODIFY_EXPR) | |
686 | return false; | |
687 | ||
688 | lhs = TREE_OPERAND (assign, 0); | |
689 | rhs = TREE_OPERAND (assign, 1); | |
690 | ass_code = TREE_CODE (rhs); | |
691 | if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) | |
692 | return false; | |
693 | op0 = TREE_OPERAND (rhs, 0); | |
694 | op1 = TREE_OPERAND (rhs, 1); | |
695 | ||
696 | if (true_edge->src == middle_bb) | |
697 | { | |
698 | /* We got here if the condition is true, i.e., SMALLER < LARGER. */ | |
699 | if (!operand_equal_for_phi_arg_p (lhs, arg_true)) | |
700 | return false; | |
701 | ||
702 | if (operand_equal_for_phi_arg_p (arg_false, larger)) | |
703 | { | |
704 | /* Case | |
705 | ||
706 | if (smaller < larger) | |
707 | { | |
708 | r' = MAX_EXPR (smaller, bound) | |
709 | } | |
710 | r = PHI <r', larger> --> to be turned to MIN_EXPR. */ | |
711 | if (ass_code != MAX_EXPR) | |
712 | return false; | |
713 | ||
714 | minmax = MIN_EXPR; | |
715 | if (operand_equal_for_phi_arg_p (op0, smaller)) | |
716 | bound = op1; | |
717 | else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
718 | bound = op0; | |
719 | else | |
720 | return false; | |
721 | ||
722 | /* We need BOUND <= LARGER. */ | |
723 | if (!integer_nonzerop (fold (build2 (LE_EXPR, boolean_type_node, | |
724 | bound, larger)))) | |
725 | return false; | |
726 | } | |
727 | else if (operand_equal_for_phi_arg_p (arg_false, smaller)) | |
728 | { | |
729 | /* Case | |
730 | ||
731 | if (smaller < larger) | |
732 | { | |
733 | r' = MIN_EXPR (larger, bound) | |
734 | } | |
735 | r = PHI <r', smaller> --> to be turned to MAX_EXPR. */ | |
736 | if (ass_code != MIN_EXPR) | |
737 | return false; | |
738 | ||
739 | minmax = MAX_EXPR; | |
740 | if (operand_equal_for_phi_arg_p (op0, larger)) | |
741 | bound = op1; | |
742 | else if (operand_equal_for_phi_arg_p (op1, larger)) | |
743 | bound = op0; | |
744 | else | |
745 | return false; | |
746 | ||
747 | /* We need BOUND >= SMALLER. */ | |
748 | if (!integer_nonzerop (fold (build2 (GE_EXPR, boolean_type_node, | |
749 | bound, smaller)))) | |
750 | return false; | |
751 | } | |
752 | else | |
753 | return false; | |
754 | } | |
755 | else | |
756 | { | |
757 | /* We got here if the condition is false, i.e., SMALLER > LARGER. */ | |
758 | if (!operand_equal_for_phi_arg_p (lhs, arg_false)) | |
759 | return false; | |
760 | ||
761 | if (operand_equal_for_phi_arg_p (arg_true, larger)) | |
762 | { | |
763 | /* Case | |
764 | ||
765 | if (smaller > larger) | |
766 | { | |
767 | r' = MIN_EXPR (smaller, bound) | |
768 | } | |
769 | r = PHI <r', larger> --> to be turned to MAX_EXPR. */ | |
770 | if (ass_code != MIN_EXPR) | |
771 | return false; | |
772 | ||
773 | minmax = MAX_EXPR; | |
774 | if (operand_equal_for_phi_arg_p (op0, smaller)) | |
775 | bound = op1; | |
776 | else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
777 | bound = op0; | |
778 | else | |
779 | return false; | |
780 | ||
781 | /* We need BOUND >= LARGER. */ | |
782 | if (!integer_nonzerop (fold (build2 (GE_EXPR, boolean_type_node, | |
783 | bound, larger)))) | |
784 | return false; | |
785 | } | |
786 | else if (operand_equal_for_phi_arg_p (arg_true, smaller)) | |
787 | { | |
788 | /* Case | |
789 | ||
790 | if (smaller > larger) | |
791 | { | |
792 | r' = MAX_EXPR (larger, bound) | |
793 | } | |
794 | r = PHI <r', smaller> --> to be turned to MIN_EXPR. */ | |
795 | if (ass_code != MAX_EXPR) | |
796 | return false; | |
797 | ||
798 | minmax = MIN_EXPR; | |
799 | if (operand_equal_for_phi_arg_p (op0, larger)) | |
800 | bound = op1; | |
801 | else if (operand_equal_for_phi_arg_p (op1, larger)) | |
802 | bound = op0; | |
803 | else | |
804 | return false; | |
805 | ||
806 | /* We need BOUND <= SMALLER. */ | |
807 | if (!integer_nonzerop (fold (build2 (LE_EXPR, boolean_type_node, | |
808 | bound, smaller)))) | |
809 | return false; | |
810 | } | |
811 | else | |
812 | return false; | |
813 | } | |
814 | ||
815 | /* Move the statement from the middle block. */ | |
816 | bsi = bsi_last (cond_bb); | |
817 | bsi_from = bsi_last (middle_bb); | |
818 | bsi_move_before (&bsi_from, &bsi); | |
819 | } | |
820 | ||
821 | /* Emit the statement to compute min/max. */ | |
822 | result = duplicate_ssa_name (PHI_RESULT (phi), NULL); | |
823 | new = build2 (MODIFY_EXPR, type, result, | |
824 | build2 (minmax, type, arg0, arg1)); | |
825 | SSA_NAME_DEF_STMT (result) = new; | |
826 | bsi = bsi_last (cond_bb); | |
827 | bsi_insert_before (&bsi, new, BSI_NEW_STMT); | |
828 | ||
a4844041 | 829 | replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
194899bf | 830 | return true; |
831 | } | |
832 | ||
70512b93 | 833 | /* The function absolute_replacement does the main work of doing the absolute |
834 | replacement. Return true if the replacement is done. Otherwise return | |
835 | false. | |
836 | bb is the basic block where the replacement is going to be done on. arg0 | |
f7f07c95 | 837 | is argument 0 from the phi. Likewise for arg1. */ |
33784d89 | 838 | |
70512b93 | 839 | static bool |
33784d89 | 840 | abs_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 841 | edge e0 ATTRIBUTE_UNUSED, edge e1, |
20e5647c | 842 | tree phi, tree arg0, tree arg1) |
70512b93 | 843 | { |
844 | tree result; | |
70512b93 | 845 | tree new, cond; |
846 | block_stmt_iterator bsi; | |
847 | edge true_edge, false_edge; | |
194899bf | 848 | tree assign; |
70512b93 | 849 | edge e; |
194899bf | 850 | tree rhs, lhs; |
70512b93 | 851 | bool negate; |
852 | enum tree_code cond_code; | |
853 | ||
854 | /* If the type says honor signed zeros we cannot do this | |
dac49aa5 | 855 | optimization. */ |
70512b93 | 856 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) |
857 | return false; | |
858 | ||
70512b93 | 859 | /* OTHER_BLOCK must have only one executable statement which must have the |
860 | form arg0 = -arg1 or arg1 = -arg0. */ | |
70512b93 | 861 | |
194899bf | 862 | assign = last_and_only_stmt (middle_bb); |
70512b93 | 863 | /* If we did not find the proper negation assignment, then we can not |
864 | optimize. */ | |
865 | if (assign == NULL) | |
866 | return false; | |
194899bf | 867 | |
868 | /* If we got here, then we have found the only executable statement | |
869 | in OTHER_BLOCK. If it is anything other than arg = -arg1 or | |
870 | arg1 = -arg0, then we can not optimize. */ | |
871 | if (TREE_CODE (assign) != MODIFY_EXPR) | |
872 | return false; | |
873 | ||
874 | lhs = TREE_OPERAND (assign, 0); | |
875 | rhs = TREE_OPERAND (assign, 1); | |
876 | ||
877 | if (TREE_CODE (rhs) != NEGATE_EXPR) | |
878 | return false; | |
879 | ||
880 | rhs = TREE_OPERAND (rhs, 0); | |
881 | ||
882 | /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */ | |
883 | if (!(lhs == arg0 && rhs == arg1) | |
884 | && !(lhs == arg1 && rhs == arg0)) | |
885 | return false; | |
70512b93 | 886 | |
33784d89 | 887 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
70512b93 | 888 | result = PHI_RESULT (phi); |
889 | ||
890 | /* Only relationals comparing arg[01] against zero are interesting. */ | |
891 | cond_code = TREE_CODE (cond); | |
892 | if (cond_code != GT_EXPR && cond_code != GE_EXPR | |
893 | && cond_code != LT_EXPR && cond_code != LE_EXPR) | |
894 | return false; | |
895 | ||
dac49aa5 | 896 | /* Make sure the conditional is arg[01] OP y. */ |
70512b93 | 897 | if (TREE_OPERAND (cond, 0) != rhs) |
898 | return false; | |
899 | ||
900 | if (FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1))) | |
901 | ? real_zerop (TREE_OPERAND (cond, 1)) | |
902 | : integer_zerop (TREE_OPERAND (cond, 1))) | |
903 | ; | |
904 | else | |
905 | return false; | |
906 | ||
907 | /* We need to know which is the true edge and which is the false | |
908 | edge so that we know if have abs or negative abs. */ | |
33784d89 | 909 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
70512b93 | 910 | |
911 | /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we | |
912 | will need to negate the result. Similarly for LT_EXPR/LE_EXPR if | |
913 | the false edge goes to OTHER_BLOCK. */ | |
914 | if (cond_code == GT_EXPR || cond_code == GE_EXPR) | |
915 | e = true_edge; | |
916 | else | |
917 | e = false_edge; | |
20e5647c | 918 | |
33784d89 | 919 | if (e->dest == middle_bb) |
70512b93 | 920 | negate = true; |
921 | else | |
922 | negate = false; | |
20e5647c | 923 | |
33784d89 | 924 | result = duplicate_ssa_name (result, NULL); |
20e5647c | 925 | |
70512b93 | 926 | if (negate) |
927 | lhs = make_rename_temp (TREE_TYPE (result), NULL); | |
928 | else | |
929 | lhs = result; | |
930 | ||
dac49aa5 | 931 | /* Build the modify expression with abs expression. */ |
194899bf | 932 | new = build2 (MODIFY_EXPR, TREE_TYPE (lhs), |
933 | lhs, build1 (ABS_EXPR, TREE_TYPE (lhs), rhs)); | |
70512b93 | 934 | |
33784d89 | 935 | bsi = bsi_last (cond_bb); |
936 | bsi_insert_before (&bsi, new, BSI_NEW_STMT); | |
70512b93 | 937 | |
938 | if (negate) | |
939 | { | |
20e5647c | 940 | /* Get the right BSI. We want to insert after the recently |
70512b93 | 941 | added ABS_EXPR statement (which we know is the first statement |
942 | in the block. */ | |
194899bf | 943 | new = build2 (MODIFY_EXPR, TREE_TYPE (result), |
944 | result, build1 (NEGATE_EXPR, TREE_TYPE (lhs), lhs)); | |
70512b93 | 945 | |
946 | bsi_insert_after (&bsi, new, BSI_NEW_STMT); | |
70512b93 | 947 | } |
20e5647c | 948 | |
33784d89 | 949 | SSA_NAME_DEF_STMT (result) = new; |
a4844041 | 950 | replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
70512b93 | 951 | |
952 | /* Note that we optimized this PHI. */ | |
953 | return true; | |
954 | } | |
955 | ||
4ee9c684 | 956 | |
957 | /* Always do these optimizations if we have SSA | |
20e5647c | 958 | trees to work on. */ |
4ee9c684 | 959 | static bool |
960 | gate_phiopt (void) | |
961 | { | |
962 | return 1; | |
963 | } | |
20e5647c | 964 | |
4ee9c684 | 965 | struct tree_opt_pass pass_phiopt = |
966 | { | |
967 | "phiopt", /* name */ | |
968 | gate_phiopt, /* gate */ | |
969 | tree_ssa_phiopt, /* execute */ | |
970 | NULL, /* sub */ | |
971 | NULL, /* next */ | |
972 | 0, /* static_pass_number */ | |
973 | TV_TREE_PHIOPT, /* tv_id */ | |
f45a1ca1 | 974 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
4ee9c684 | 975 | 0, /* properties_provided */ |
976 | 0, /* properties_destroyed */ | |
977 | 0, /* todo_flags_start */ | |
88dbf20f | 978 | TODO_cleanup_cfg |
979 | | TODO_dump_func | |
980 | | TODO_ggc_collect | |
981 | | TODO_verify_ssa | |
982 | | TODO_update_ssa | |
983 | | TODO_verify_flow | |
984 | | TODO_verify_stmts, /* todo_flags_finish */ | |
0f9005dd | 985 | 0 /* letter */ |
4ee9c684 | 986 | }; |