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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); | |
81c5be57 | 334 | EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE; |
335 | EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count; | |
0e1a77e1 | 336 | |
cd665a06 | 337 | block_to_remove = EDGE_SUCC (cond_block, 1)->dest; |
902929aa | 338 | } |
339 | else | |
340 | { | |
cd665a06 | 341 | EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU; |
342 | EDGE_SUCC (cond_block, 1)->flags | |
902929aa | 343 | &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); |
81c5be57 | 344 | EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE; |
345 | EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count; | |
0e1a77e1 | 346 | |
cd665a06 | 347 | block_to_remove = EDGE_SUCC (cond_block, 0)->dest; |
902929aa | 348 | } |
0e1a77e1 | 349 | delete_basic_block (block_to_remove); |
20e5647c | 350 | |
902929aa | 351 | /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ |
352 | bsi = bsi_last (cond_block); | |
353 | bsi_remove (&bsi); | |
20e5647c | 354 | |
902929aa | 355 | if (dump_file && (dump_flags & TDF_DETAILS)) |
356 | fprintf (dump_file, | |
357 | "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n", | |
358 | cond_block->index, | |
359 | bb->index); | |
360 | } | |
361 | ||
362 | /* The function conditional_replacement does the main work of doing the | |
363 | conditional replacement. Return true if the replacement is done. | |
364 | Otherwise return false. | |
365 | BB is the basic block where the replacement is going to be done on. ARG0 | |
dac49aa5 | 366 | is argument 0 from PHI. Likewise for ARG1. */ |
902929aa | 367 | |
368 | static bool | |
33784d89 | 369 | conditional_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 370 | edge e0, edge e1, tree phi, |
33784d89 | 371 | tree arg0, tree arg1) |
902929aa | 372 | { |
373 | tree result; | |
374 | tree old_result = NULL; | |
902929aa | 375 | tree new, cond; |
376 | block_stmt_iterator bsi; | |
377 | edge true_edge, false_edge; | |
378 | tree new_var = NULL; | |
33784d89 | 379 | tree new_var1; |
902929aa | 380 | |
381 | /* The PHI arguments have the constants 0 and 1, then convert | |
382 | it to the conditional. */ | |
383 | if ((integer_zerop (arg0) && integer_onep (arg1)) | |
384 | || (integer_zerop (arg1) && integer_onep (arg0))) | |
385 | ; | |
386 | else | |
387 | return false; | |
20e5647c | 388 | |
33784d89 | 389 | if (!empty_block_p (middle_bb)) |
902929aa | 390 | return false; |
20e5647c | 391 | |
4ee9c684 | 392 | /* If the condition is not a naked SSA_NAME and its type does not |
2ab0a163 | 393 | match the type of the result, then we have to create a new |
394 | variable to optimize this case as it would likely create | |
395 | non-gimple code when the condition was converted to the | |
396 | result's type. */ | |
33784d89 | 397 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
4ee9c684 | 398 | result = PHI_RESULT (phi); |
399 | if (TREE_CODE (cond) != SSA_NAME | |
400 | && !lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result))) | |
ae5a4794 | 401 | { |
b2a02a0e | 402 | tree tmp; |
403 | ||
404 | if (!COMPARISON_CLASS_P (cond)) | |
405 | return false; | |
406 | ||
407 | tmp = create_tmp_var (TREE_TYPE (cond), NULL); | |
408 | add_referenced_tmp_var (tmp); | |
409 | new_var = make_ssa_name (tmp, NULL); | |
ae5a4794 | 410 | old_result = cond; |
411 | cond = new_var; | |
412 | } | |
20e5647c | 413 | |
4ee9c684 | 414 | /* If the condition was a naked SSA_NAME and the type is not the |
2ab0a163 | 415 | same as the type of the result, then convert the type of the |
416 | condition. */ | |
4ee9c684 | 417 | if (!lang_hooks.types_compatible_p (TREE_TYPE (cond), TREE_TYPE (result))) |
418 | cond = fold_convert (TREE_TYPE (result), cond); | |
20e5647c | 419 | |
4ee9c684 | 420 | /* We need to know which is the true edge and which is the false |
2ab0a163 | 421 | edge so that we know when to invert the condition below. */ |
33784d89 | 422 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
20e5647c | 423 | |
1fa68a1f | 424 | /* Insert our new statement at the end of conditional block before the |
33784d89 | 425 | COND_EXPR. */ |
426 | bsi = bsi_last (cond_bb); | |
427 | bsi_insert_before (&bsi, build_empty_stmt (), BSI_NEW_STMT); | |
20e5647c | 428 | |
ae5a4794 | 429 | if (old_result) |
430 | { | |
431 | tree new1; | |
20e5647c | 432 | |
194899bf | 433 | new1 = build2 (TREE_CODE (old_result), TREE_TYPE (old_result), |
434 | TREE_OPERAND (old_result, 0), | |
435 | TREE_OPERAND (old_result, 1)); | |
20e5647c | 436 | |
194899bf | 437 | new1 = build2 (MODIFY_EXPR, TREE_TYPE (old_result), new_var, new1); |
b2a02a0e | 438 | SSA_NAME_DEF_STMT (new_var) = new1; |
439 | ||
ae5a4794 | 440 | bsi_insert_after (&bsi, new1, BSI_NEW_STMT); |
441 | } | |
20e5647c | 442 | |
33784d89 | 443 | new_var1 = duplicate_ssa_name (PHI_RESULT (phi), NULL); |
20e5647c | 444 | |
445 | ||
4ee9c684 | 446 | /* At this point we know we have a COND_EXPR with two successors. |
2ab0a163 | 447 | One successor is BB, the other successor is an empty block which |
448 | falls through into BB. | |
20e5647c | 449 | |
2ab0a163 | 450 | There is a single PHI node at the join point (BB) and its arguments |
451 | are constants (0, 1). | |
20e5647c | 452 | |
2ab0a163 | 453 | So, given the condition COND, and the two PHI arguments, we can |
20e5647c | 454 | rewrite this PHI into non-branching code: |
455 | ||
2ab0a163 | 456 | dest = (COND) or dest = COND' |
20e5647c | 457 | |
2ab0a163 | 458 | We use the condition as-is if the argument associated with the |
459 | true edge has the value one or the argument associated with the | |
460 | false edge as the value zero. Note that those conditions are not | |
461 | the same since only one of the outgoing edges from the COND_EXPR | |
462 | will directly reach BB and thus be associated with an argument. */ | |
33784d89 | 463 | if ((e0 == true_edge && integer_onep (arg0)) |
464 | || (e0 == false_edge && integer_zerop (arg0)) | |
465 | || (e1 == true_edge && integer_onep (arg1)) | |
466 | || (e1 == false_edge && integer_zerop (arg1))) | |
4ee9c684 | 467 | { |
194899bf | 468 | new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond); |
4ee9c684 | 469 | } |
470 | else | |
471 | { | |
ae5a4794 | 472 | tree cond1 = invert_truthvalue (cond); |
20e5647c | 473 | |
ae5a4794 | 474 | cond = cond1; |
b2a02a0e | 475 | |
ae5a4794 | 476 | /* If what we get back is a conditional expression, there is no |
0beac6fc | 477 | way that it can be gimple. */ |
ae5a4794 | 478 | if (TREE_CODE (cond) == COND_EXPR) |
33784d89 | 479 | { |
480 | release_ssa_name (new_var1); | |
20e5647c | 481 | return false; |
33784d89 | 482 | } |
ae5a4794 | 483 | |
b2a02a0e | 484 | /* If COND is not something we can expect to be reducible to a GIMPLE |
485 | condition, return early. */ | |
486 | if (is_gimple_cast (cond)) | |
487 | cond1 = TREE_OPERAND (cond, 0); | |
488 | if (TREE_CODE (cond1) == TRUTH_NOT_EXPR | |
489 | && !is_gimple_val (TREE_OPERAND (cond1, 0))) | |
490 | { | |
491 | release_ssa_name (new_var1); | |
492 | return false; | |
493 | } | |
494 | ||
ae5a4794 | 495 | /* If what we get back is not gimple try to create it as gimple by |
dac49aa5 | 496 | using a temporary variable. */ |
4ee9c684 | 497 | if (is_gimple_cast (cond) |
498 | && !is_gimple_val (TREE_OPERAND (cond, 0))) | |
2ab0a163 | 499 | { |
b2a02a0e | 500 | tree op0, tmp, cond_tmp; |
20e5647c | 501 | |
b2a02a0e | 502 | /* Only "real" casts are OK here, not everything that is |
503 | acceptable to is_gimple_cast. Make sure we don't do | |
504 | anything stupid here. */ | |
505 | gcc_assert (TREE_CODE (cond) == NOP_EXPR | |
506 | || TREE_CODE (cond) == CONVERT_EXPR); | |
507 | ||
508 | op0 = TREE_OPERAND (cond, 0); | |
509 | tmp = create_tmp_var (TREE_TYPE (op0), NULL); | |
510 | add_referenced_tmp_var (tmp); | |
511 | cond_tmp = make_ssa_name (tmp, NULL); | |
512 | new = build2 (MODIFY_EXPR, TREE_TYPE (cond_tmp), cond_tmp, op0); | |
513 | SSA_NAME_DEF_STMT (cond_tmp) = new; | |
514 | ||
515 | bsi_insert_after (&bsi, new, BSI_NEW_STMT); | |
516 | cond = fold_convert (TREE_TYPE (result), cond_tmp); | |
33784d89 | 517 | } |
4ee9c684 | 518 | |
194899bf | 519 | new = build2 (MODIFY_EXPR, TREE_TYPE (new_var1), new_var1, cond); |
4ee9c684 | 520 | } |
20e5647c | 521 | |
33784d89 | 522 | bsi_insert_after (&bsi, new, BSI_NEW_STMT); |
20e5647c | 523 | |
33784d89 | 524 | SSA_NAME_DEF_STMT (new_var1) = new; |
20e5647c | 525 | |
a4844041 | 526 | replace_phi_edge_with_variable (cond_bb, e1, phi, new_var1); |
902929aa | 527 | |
4ee9c684 | 528 | /* Note that we optimized this PHI. */ |
529 | return true; | |
530 | } | |
531 | ||
0beac6fc | 532 | /* The function value_replacement does the main work of doing the value |
533 | replacement. Return true if the replacement is done. Otherwise return | |
534 | false. | |
535 | BB is the basic block where the replacement is going to be done on. ARG0 | |
dac49aa5 | 536 | is argument 0 from the PHI. Likewise for ARG1. */ |
0beac6fc | 537 | |
538 | static bool | |
33784d89 | 539 | value_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 540 | edge e0, edge e1, tree phi, |
33784d89 | 541 | tree arg0, tree arg1) |
0beac6fc | 542 | { |
33784d89 | 543 | tree cond; |
0beac6fc | 544 | edge true_edge, false_edge; |
545 | ||
546 | /* If the type says honor signed zeros we cannot do this | |
dac49aa5 | 547 | optimization. */ |
0beac6fc | 548 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) |
549 | return false; | |
550 | ||
33784d89 | 551 | if (!empty_block_p (middle_bb)) |
0beac6fc | 552 | return false; |
553 | ||
33784d89 | 554 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
0beac6fc | 555 | |
556 | /* This transformation is only valid for equality comparisons. */ | |
557 | if (TREE_CODE (cond) != NE_EXPR && TREE_CODE (cond) != EQ_EXPR) | |
558 | return false; | |
559 | ||
560 | /* We need to know which is the true edge and which is the false | |
561 | edge so that we know if have abs or negative abs. */ | |
33784d89 | 562 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
0beac6fc | 563 | |
564 | /* At this point we know we have a COND_EXPR with two successors. | |
565 | One successor is BB, the other successor is an empty block which | |
566 | falls through into BB. | |
567 | ||
568 | The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR. | |
569 | ||
570 | There is a single PHI node at the join point (BB) with two arguments. | |
571 | ||
572 | We now need to verify that the two arguments in the PHI node match | |
573 | the two arguments to the equality comparison. */ | |
20e5647c | 574 | |
5373158f | 575 | if ((operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 0)) |
576 | && operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 1))) | |
577 | || (operand_equal_for_phi_arg_p (arg1, TREE_OPERAND (cond, 0)) | |
578 | && operand_equal_for_phi_arg_p (arg0, TREE_OPERAND (cond, 1)))) | |
0beac6fc | 579 | { |
580 | edge e; | |
581 | tree arg; | |
582 | ||
50737d20 | 583 | /* For NE_EXPR, we want to build an assignment result = arg where |
584 | arg is the PHI argument associated with the true edge. For | |
585 | EQ_EXPR we want the PHI argument associated with the false edge. */ | |
0beac6fc | 586 | e = (TREE_CODE (cond) == NE_EXPR ? true_edge : false_edge); |
50737d20 | 587 | |
588 | /* Unfortunately, E may not reach BB (it may instead have gone to | |
589 | OTHER_BLOCK). If that is the case, then we want the single outgoing | |
590 | edge from OTHER_BLOCK which reaches BB and represents the desired | |
591 | path from COND_BLOCK. */ | |
33784d89 | 592 | if (e->dest == middle_bb) |
ea091dfd | 593 | e = single_succ_edge (e->dest); |
50737d20 | 594 | |
595 | /* Now we know the incoming edge to BB that has the argument for the | |
596 | RHS of our new assignment statement. */ | |
33784d89 | 597 | if (e0 == e) |
0beac6fc | 598 | arg = arg0; |
599 | else | |
600 | arg = arg1; | |
601 | ||
a4844041 | 602 | replace_phi_edge_with_variable (cond_bb, e1, phi, arg); |
0beac6fc | 603 | |
604 | /* Note that we optimized this PHI. */ | |
605 | return true; | |
606 | } | |
607 | return false; | |
608 | } | |
609 | ||
194899bf | 610 | /* The function minmax_replacement does the main work of doing the minmax |
611 | replacement. Return true if the replacement is done. Otherwise return | |
612 | false. | |
613 | BB is the basic block where the replacement is going to be done on. ARG0 | |
614 | is argument 0 from the PHI. Likewise for ARG1. */ | |
615 | ||
616 | static bool | |
617 | minmax_replacement (basic_block cond_bb, basic_block middle_bb, | |
a4844041 | 618 | edge e0, edge e1, tree phi, |
194899bf | 619 | tree arg0, tree arg1) |
620 | { | |
621 | tree result, type; | |
622 | tree cond, new; | |
623 | edge true_edge, false_edge; | |
624 | enum tree_code cmp, minmax, ass_code; | |
625 | tree smaller, larger, arg_true, arg_false; | |
626 | block_stmt_iterator bsi, bsi_from; | |
627 | ||
628 | type = TREE_TYPE (PHI_RESULT (phi)); | |
629 | ||
630 | /* The optimization may be unsafe due to NaNs. */ | |
631 | if (HONOR_NANS (TYPE_MODE (type))) | |
632 | return false; | |
633 | ||
634 | cond = COND_EXPR_COND (last_stmt (cond_bb)); | |
635 | cmp = TREE_CODE (cond); | |
636 | result = PHI_RESULT (phi); | |
637 | ||
638 | /* This transformation is only valid for order comparisons. Record which | |
639 | operand is smaller/larger if the result of the comparison is true. */ | |
640 | if (cmp == LT_EXPR || cmp == LE_EXPR) | |
641 | { | |
642 | smaller = TREE_OPERAND (cond, 0); | |
643 | larger = TREE_OPERAND (cond, 1); | |
644 | } | |
645 | else if (cmp == GT_EXPR || cmp == GE_EXPR) | |
646 | { | |
647 | smaller = TREE_OPERAND (cond, 1); | |
648 | larger = TREE_OPERAND (cond, 0); | |
649 | } | |
650 | else | |
651 | return false; | |
652 | ||
653 | /* We need to know which is the true edge and which is the false | |
654 | edge so that we know if have abs or negative abs. */ | |
655 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); | |
656 | ||
657 | /* Forward the edges over the middle basic block. */ | |
658 | if (true_edge->dest == middle_bb) | |
659 | true_edge = EDGE_SUCC (true_edge->dest, 0); | |
660 | if (false_edge->dest == middle_bb) | |
661 | false_edge = EDGE_SUCC (false_edge->dest, 0); | |
662 | ||
663 | if (true_edge == e0) | |
664 | { | |
665 | gcc_assert (false_edge == e1); | |
666 | arg_true = arg0; | |
667 | arg_false = arg1; | |
668 | } | |
669 | else | |
670 | { | |
671 | gcc_assert (false_edge == e0); | |
672 | gcc_assert (true_edge == e1); | |
673 | arg_true = arg1; | |
674 | arg_false = arg0; | |
675 | } | |
676 | ||
677 | if (empty_block_p (middle_bb)) | |
678 | { | |
679 | if (operand_equal_for_phi_arg_p (arg_true, smaller) | |
680 | && operand_equal_for_phi_arg_p (arg_false, larger)) | |
681 | { | |
682 | /* Case | |
683 | ||
684 | if (smaller < larger) | |
685 | rslt = smaller; | |
686 | else | |
687 | rslt = larger; */ | |
688 | minmax = MIN_EXPR; | |
689 | } | |
690 | else if (operand_equal_for_phi_arg_p (arg_false, smaller) | |
691 | && operand_equal_for_phi_arg_p (arg_true, larger)) | |
692 | minmax = MAX_EXPR; | |
693 | else | |
694 | return false; | |
695 | } | |
696 | else | |
697 | { | |
698 | /* Recognize the following case, assuming d <= u: | |
699 | ||
700 | if (a <= u) | |
701 | b = MAX (a, d); | |
702 | x = PHI <b, u> | |
703 | ||
704 | This is equivalent to | |
705 | ||
706 | b = MAX (a, d); | |
707 | x = MIN (b, u); */ | |
708 | ||
709 | tree assign = last_and_only_stmt (middle_bb); | |
710 | tree lhs, rhs, op0, op1, bound; | |
711 | ||
712 | if (!assign | |
713 | || TREE_CODE (assign) != MODIFY_EXPR) | |
714 | return false; | |
715 | ||
716 | lhs = TREE_OPERAND (assign, 0); | |
717 | rhs = TREE_OPERAND (assign, 1); | |
718 | ass_code = TREE_CODE (rhs); | |
719 | if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) | |
720 | return false; | |
721 | op0 = TREE_OPERAND (rhs, 0); | |
722 | op1 = TREE_OPERAND (rhs, 1); | |
723 | ||
724 | if (true_edge->src == middle_bb) | |
725 | { | |
726 | /* We got here if the condition is true, i.e., SMALLER < LARGER. */ | |
727 | if (!operand_equal_for_phi_arg_p (lhs, arg_true)) | |
728 | return false; | |
729 | ||
730 | if (operand_equal_for_phi_arg_p (arg_false, larger)) | |
731 | { | |
732 | /* Case | |
733 | ||
734 | if (smaller < larger) | |
735 | { | |
736 | r' = MAX_EXPR (smaller, bound) | |
737 | } | |
738 | r = PHI <r', larger> --> to be turned to MIN_EXPR. */ | |
739 | if (ass_code != MAX_EXPR) | |
740 | return false; | |
741 | ||
742 | minmax = MIN_EXPR; | |
743 | if (operand_equal_for_phi_arg_p (op0, smaller)) | |
744 | bound = op1; | |
745 | else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
746 | bound = op0; | |
747 | else | |
748 | return false; | |
749 | ||
750 | /* We need BOUND <= LARGER. */ | |
49d00087 | 751 | if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, |
752 | bound, larger))) | |
194899bf | 753 | return false; |
754 | } | |
755 | else if (operand_equal_for_phi_arg_p (arg_false, smaller)) | |
756 | { | |
757 | /* Case | |
758 | ||
759 | if (smaller < larger) | |
760 | { | |
761 | r' = MIN_EXPR (larger, bound) | |
762 | } | |
763 | r = PHI <r', smaller> --> to be turned to MAX_EXPR. */ | |
764 | if (ass_code != MIN_EXPR) | |
765 | return false; | |
766 | ||
767 | minmax = MAX_EXPR; | |
768 | if (operand_equal_for_phi_arg_p (op0, larger)) | |
769 | bound = op1; | |
770 | else if (operand_equal_for_phi_arg_p (op1, larger)) | |
771 | bound = op0; | |
772 | else | |
773 | return false; | |
774 | ||
775 | /* We need BOUND >= SMALLER. */ | |
49d00087 | 776 | if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, |
777 | bound, smaller))) | |
194899bf | 778 | return false; |
779 | } | |
780 | else | |
781 | return false; | |
782 | } | |
783 | else | |
784 | { | |
785 | /* We got here if the condition is false, i.e., SMALLER > LARGER. */ | |
786 | if (!operand_equal_for_phi_arg_p (lhs, arg_false)) | |
787 | return false; | |
788 | ||
789 | if (operand_equal_for_phi_arg_p (arg_true, larger)) | |
790 | { | |
791 | /* Case | |
792 | ||
793 | if (smaller > larger) | |
794 | { | |
795 | r' = MIN_EXPR (smaller, bound) | |
796 | } | |
797 | r = PHI <r', larger> --> to be turned to MAX_EXPR. */ | |
798 | if (ass_code != MIN_EXPR) | |
799 | return false; | |
800 | ||
801 | minmax = MAX_EXPR; | |
802 | if (operand_equal_for_phi_arg_p (op0, smaller)) | |
803 | bound = op1; | |
804 | else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
805 | bound = op0; | |
806 | else | |
807 | return false; | |
808 | ||
809 | /* We need BOUND >= LARGER. */ | |
49d00087 | 810 | if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, |
811 | bound, larger))) | |
194899bf | 812 | return false; |
813 | } | |
814 | else if (operand_equal_for_phi_arg_p (arg_true, smaller)) | |
815 | { | |
816 | /* Case | |
817 | ||
818 | if (smaller > larger) | |
819 | { | |
820 | r' = MAX_EXPR (larger, bound) | |
821 | } | |
822 | r = PHI <r', smaller> --> to be turned to MIN_EXPR. */ | |
823 | if (ass_code != MAX_EXPR) | |
824 | return false; | |
825 | ||
826 | minmax = MIN_EXPR; | |
827 | if (operand_equal_for_phi_arg_p (op0, larger)) | |
828 | bound = op1; | |
829 | else if (operand_equal_for_phi_arg_p (op1, larger)) | |
830 | bound = op0; | |
831 | else | |
832 | return false; | |
833 | ||
834 | /* We need BOUND <= SMALLER. */ | |
49d00087 | 835 | if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, |
836 | bound, smaller))) | |
194899bf | 837 | return false; |
838 | } | |
839 | else | |
840 | return false; | |
841 | } | |
842 | ||
843 | /* Move the statement from the middle block. */ | |
844 | bsi = bsi_last (cond_bb); | |
845 | bsi_from = bsi_last (middle_bb); | |
846 | bsi_move_before (&bsi_from, &bsi); | |
847 | } | |
848 | ||
849 | /* Emit the statement to compute min/max. */ | |
850 | result = duplicate_ssa_name (PHI_RESULT (phi), NULL); | |
851 | new = build2 (MODIFY_EXPR, type, result, | |
852 | build2 (minmax, type, arg0, arg1)); | |
853 | SSA_NAME_DEF_STMT (result) = new; | |
854 | bsi = bsi_last (cond_bb); | |
855 | bsi_insert_before (&bsi, new, BSI_NEW_STMT); | |
856 | ||
a4844041 | 857 | replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
194899bf | 858 | return true; |
859 | } | |
860 | ||
70512b93 | 861 | /* The function absolute_replacement does the main work of doing the absolute |
862 | replacement. Return true if the replacement is done. Otherwise return | |
863 | false. | |
864 | bb is the basic block where the replacement is going to be done on. arg0 | |
f7f07c95 | 865 | is argument 0 from the phi. Likewise for arg1. */ |
33784d89 | 866 | |
70512b93 | 867 | static bool |
33784d89 | 868 | abs_replacement (basic_block cond_bb, basic_block middle_bb, |
a4844041 | 869 | edge e0 ATTRIBUTE_UNUSED, edge e1, |
20e5647c | 870 | tree phi, tree arg0, tree arg1) |
70512b93 | 871 | { |
872 | tree result; | |
70512b93 | 873 | tree new, cond; |
874 | block_stmt_iterator bsi; | |
875 | edge true_edge, false_edge; | |
194899bf | 876 | tree assign; |
70512b93 | 877 | edge e; |
194899bf | 878 | tree rhs, lhs; |
70512b93 | 879 | bool negate; |
880 | enum tree_code cond_code; | |
881 | ||
882 | /* If the type says honor signed zeros we cannot do this | |
dac49aa5 | 883 | optimization. */ |
70512b93 | 884 | if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) |
885 | return false; | |
886 | ||
70512b93 | 887 | /* OTHER_BLOCK must have only one executable statement which must have the |
888 | form arg0 = -arg1 or arg1 = -arg0. */ | |
70512b93 | 889 | |
194899bf | 890 | assign = last_and_only_stmt (middle_bb); |
70512b93 | 891 | /* If we did not find the proper negation assignment, then we can not |
892 | optimize. */ | |
893 | if (assign == NULL) | |
894 | return false; | |
194899bf | 895 | |
896 | /* If we got here, then we have found the only executable statement | |
897 | in OTHER_BLOCK. If it is anything other than arg = -arg1 or | |
898 | arg1 = -arg0, then we can not optimize. */ | |
899 | if (TREE_CODE (assign) != MODIFY_EXPR) | |
900 | return false; | |
901 | ||
902 | lhs = TREE_OPERAND (assign, 0); | |
903 | rhs = TREE_OPERAND (assign, 1); | |
904 | ||
905 | if (TREE_CODE (rhs) != NEGATE_EXPR) | |
906 | return false; | |
907 | ||
908 | rhs = TREE_OPERAND (rhs, 0); | |
909 | ||
910 | /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */ | |
911 | if (!(lhs == arg0 && rhs == arg1) | |
912 | && !(lhs == arg1 && rhs == arg0)) | |
913 | return false; | |
70512b93 | 914 | |
33784d89 | 915 | cond = COND_EXPR_COND (last_stmt (cond_bb)); |
70512b93 | 916 | result = PHI_RESULT (phi); |
917 | ||
918 | /* Only relationals comparing arg[01] against zero are interesting. */ | |
919 | cond_code = TREE_CODE (cond); | |
920 | if (cond_code != GT_EXPR && cond_code != GE_EXPR | |
921 | && cond_code != LT_EXPR && cond_code != LE_EXPR) | |
922 | return false; | |
923 | ||
dac49aa5 | 924 | /* Make sure the conditional is arg[01] OP y. */ |
70512b93 | 925 | if (TREE_OPERAND (cond, 0) != rhs) |
926 | return false; | |
927 | ||
928 | if (FLOAT_TYPE_P (TREE_TYPE (TREE_OPERAND (cond, 1))) | |
929 | ? real_zerop (TREE_OPERAND (cond, 1)) | |
930 | : integer_zerop (TREE_OPERAND (cond, 1))) | |
931 | ; | |
932 | else | |
933 | return false; | |
934 | ||
935 | /* We need to know which is the true edge and which is the false | |
936 | edge so that we know if have abs or negative abs. */ | |
33784d89 | 937 | extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); |
70512b93 | 938 | |
939 | /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we | |
940 | will need to negate the result. Similarly for LT_EXPR/LE_EXPR if | |
941 | the false edge goes to OTHER_BLOCK. */ | |
942 | if (cond_code == GT_EXPR || cond_code == GE_EXPR) | |
943 | e = true_edge; | |
944 | else | |
945 | e = false_edge; | |
20e5647c | 946 | |
33784d89 | 947 | if (e->dest == middle_bb) |
70512b93 | 948 | negate = true; |
949 | else | |
950 | negate = false; | |
20e5647c | 951 | |
33784d89 | 952 | result = duplicate_ssa_name (result, NULL); |
20e5647c | 953 | |
70512b93 | 954 | if (negate) |
b2a02a0e | 955 | { |
956 | tree tmp = create_tmp_var (TREE_TYPE (result), NULL); | |
957 | add_referenced_tmp_var (tmp); | |
958 | lhs = make_ssa_name (tmp, NULL); | |
959 | } | |
70512b93 | 960 | else |
961 | lhs = result; | |
962 | ||
dac49aa5 | 963 | /* Build the modify expression with abs expression. */ |
194899bf | 964 | new = build2 (MODIFY_EXPR, TREE_TYPE (lhs), |
965 | lhs, build1 (ABS_EXPR, TREE_TYPE (lhs), rhs)); | |
b2a02a0e | 966 | SSA_NAME_DEF_STMT (lhs) = new; |
70512b93 | 967 | |
33784d89 | 968 | bsi = bsi_last (cond_bb); |
969 | bsi_insert_before (&bsi, new, BSI_NEW_STMT); | |
70512b93 | 970 | |
971 | if (negate) | |
972 | { | |
20e5647c | 973 | /* Get the right BSI. We want to insert after the recently |
70512b93 | 974 | added ABS_EXPR statement (which we know is the first statement |
975 | in the block. */ | |
194899bf | 976 | new = build2 (MODIFY_EXPR, TREE_TYPE (result), |
977 | result, build1 (NEGATE_EXPR, TREE_TYPE (lhs), lhs)); | |
b2a02a0e | 978 | SSA_NAME_DEF_STMT (result) = new; |
70512b93 | 979 | |
980 | bsi_insert_after (&bsi, new, BSI_NEW_STMT); | |
70512b93 | 981 | } |
20e5647c | 982 | |
a4844041 | 983 | replace_phi_edge_with_variable (cond_bb, e1, phi, result); |
70512b93 | 984 | |
985 | /* Note that we optimized this PHI. */ | |
986 | return true; | |
987 | } | |
988 | ||
4ee9c684 | 989 | |
990 | /* Always do these optimizations if we have SSA | |
20e5647c | 991 | trees to work on. */ |
4ee9c684 | 992 | static bool |
993 | gate_phiopt (void) | |
994 | { | |
995 | return 1; | |
996 | } | |
20e5647c | 997 | |
4ee9c684 | 998 | struct tree_opt_pass pass_phiopt = |
999 | { | |
1000 | "phiopt", /* name */ | |
1001 | gate_phiopt, /* gate */ | |
1002 | tree_ssa_phiopt, /* execute */ | |
1003 | NULL, /* sub */ | |
1004 | NULL, /* next */ | |
1005 | 0, /* static_pass_number */ | |
1006 | TV_TREE_PHIOPT, /* tv_id */ | |
f45a1ca1 | 1007 | PROP_cfg | PROP_ssa | PROP_alias, /* properties_required */ |
4ee9c684 | 1008 | 0, /* properties_provided */ |
1009 | 0, /* properties_destroyed */ | |
1010 | 0, /* todo_flags_start */ | |
88dbf20f | 1011 | TODO_cleanup_cfg |
1012 | | TODO_dump_func | |
1013 | | TODO_ggc_collect | |
1014 | | TODO_verify_ssa | |
88dbf20f | 1015 | | TODO_verify_flow |
1016 | | TODO_verify_stmts, /* todo_flags_finish */ | |
0f9005dd | 1017 | 0 /* letter */ |
4ee9c684 | 1018 | }; |