Mercurial > hg > CbC > CbC_gcc
annotate gcc/tree-ssa-phiopt.c @ 55:77e2b8dfacca gcc-4.4.5
update it from 4.4.3 to 4.5.0
| author | ryoma <e075725@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Fri, 12 Feb 2010 23:39:51 +0900 |
| parents | a06113de4d67 |
| children | b7f97abdc517 |
| rev | line source |
|---|---|
| 0 | 1 /* Optimization of PHI nodes by converting them into straightline code. |
| 2 Copyright (C) 2004, 2005, 2006, 2007, 2008 Free Software Foundation, | |
| 3 Inc. | |
| 4 | |
| 5 This file is part of GCC. | |
| 6 | |
| 7 GCC is free software; you can redistribute it and/or modify it | |
| 8 under the terms of the GNU General Public License as published by the | |
| 9 Free Software Foundation; either version 3, or (at your option) any | |
| 10 later version. | |
| 11 | |
| 12 GCC is distributed in the hope that it will be useful, but WITHOUT | |
| 13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
| 14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
| 15 for more details. | |
| 16 | |
| 17 You should have received a copy of the GNU General Public License | |
| 18 along with GCC; see the file COPYING3. If not see | |
| 19 <http://www.gnu.org/licenses/>. */ | |
| 20 | |
| 21 #include "config.h" | |
| 22 #include "system.h" | |
| 23 #include "coretypes.h" | |
| 24 #include "tm.h" | |
| 25 #include "ggc.h" | |
| 26 #include "tree.h" | |
| 27 #include "rtl.h" | |
| 28 #include "flags.h" | |
| 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 #include "pointer-set.h" | |
| 38 #include "domwalk.h" | |
| 39 | |
| 40 static unsigned int tree_ssa_phiopt (void); | |
| 41 static unsigned int tree_ssa_phiopt_worker (bool); | |
| 42 static bool conditional_replacement (basic_block, basic_block, | |
| 43 edge, edge, gimple, tree, tree); | |
| 44 static bool value_replacement (basic_block, basic_block, | |
| 45 edge, edge, gimple, tree, tree); | |
| 46 static bool minmax_replacement (basic_block, basic_block, | |
| 47 edge, edge, gimple, tree, tree); | |
| 48 static bool abs_replacement (basic_block, basic_block, | |
| 49 edge, edge, gimple, tree, tree); | |
| 50 static bool cond_store_replacement (basic_block, basic_block, edge, edge, | |
| 51 struct pointer_set_t *); | |
| 52 static struct pointer_set_t * get_non_trapping (void); | |
| 53 static void replace_phi_edge_with_variable (basic_block, edge, gimple, tree); | |
| 54 | |
| 55 /* This pass tries to replaces an if-then-else block with an | |
| 56 assignment. We have four kinds of transformations. Some of these | |
| 57 transformations are also performed by the ifcvt RTL optimizer. | |
| 58 | |
| 59 Conditional Replacement | |
| 60 ----------------------- | |
| 61 | |
| 62 This transformation, implemented in conditional_replacement, | |
| 63 replaces | |
| 64 | |
| 65 bb0: | |
| 66 if (cond) goto bb2; else goto bb1; | |
| 67 bb1: | |
| 68 bb2: | |
| 69 x = PHI <0 (bb1), 1 (bb0), ...>; | |
| 70 | |
| 71 with | |
| 72 | |
| 73 bb0: | |
| 74 x' = cond; | |
| 75 goto bb2; | |
| 76 bb2: | |
| 77 x = PHI <x' (bb0), ...>; | |
| 78 | |
| 79 We remove bb1 as it becomes unreachable. This occurs often due to | |
| 80 gimplification of conditionals. | |
| 81 | |
| 82 Value Replacement | |
| 83 ----------------- | |
| 84 | |
| 85 This transformation, implemented in value_replacement, replaces | |
| 86 | |
| 87 bb0: | |
| 88 if (a != b) goto bb2; else goto bb1; | |
| 89 bb1: | |
| 90 bb2: | |
| 91 x = PHI <a (bb1), b (bb0), ...>; | |
| 92 | |
| 93 with | |
| 94 | |
| 95 bb0: | |
| 96 bb2: | |
| 97 x = PHI <b (bb0), ...>; | |
| 98 | |
| 99 This opportunity can sometimes occur as a result of other | |
| 100 optimizations. | |
| 101 | |
| 102 ABS Replacement | |
| 103 --------------- | |
| 104 | |
| 105 This transformation, implemented in abs_replacement, replaces | |
| 106 | |
| 107 bb0: | |
| 108 if (a >= 0) goto bb2; else goto bb1; | |
| 109 bb1: | |
| 110 x = -a; | |
| 111 bb2: | |
| 112 x = PHI <x (bb1), a (bb0), ...>; | |
| 113 | |
| 114 with | |
| 115 | |
| 116 bb0: | |
| 117 x' = ABS_EXPR< a >; | |
| 118 bb2: | |
| 119 x = PHI <x' (bb0), ...>; | |
| 120 | |
| 121 MIN/MAX Replacement | |
| 122 ------------------- | |
| 123 | |
| 124 This transformation, minmax_replacement replaces | |
| 125 | |
| 126 bb0: | |
| 127 if (a <= b) goto bb2; else goto bb1; | |
| 128 bb1: | |
| 129 bb2: | |
| 130 x = PHI <b (bb1), a (bb0), ...>; | |
| 131 | |
| 132 with | |
| 133 | |
| 134 bb0: | |
| 135 x' = MIN_EXPR (a, b) | |
| 136 bb2: | |
| 137 x = PHI <x' (bb0), ...>; | |
| 138 | |
| 139 A similar transformation is done for MAX_EXPR. */ | |
| 140 | |
| 141 static unsigned int | |
| 142 tree_ssa_phiopt (void) | |
| 143 { | |
| 144 return tree_ssa_phiopt_worker (false); | |
| 145 } | |
| 146 | |
| 147 /* This pass tries to transform conditional stores into unconditional | |
| 148 ones, enabling further simplifications with the simpler then and else | |
| 149 blocks. In particular it replaces this: | |
| 150 | |
| 151 bb0: | |
| 152 if (cond) goto bb2; else goto bb1; | |
| 153 bb1: | |
| 154 *p = RHS | |
| 155 bb2: | |
| 156 | |
| 157 with | |
| 158 | |
| 159 bb0: | |
| 160 if (cond) goto bb1; else goto bb2; | |
| 161 bb1: | |
| 162 condtmp' = *p; | |
| 163 bb2: | |
| 164 condtmp = PHI <RHS, condtmp'> | |
| 165 *p = condtmp | |
| 166 | |
| 167 This transformation can only be done under several constraints, | |
| 168 documented below. */ | |
| 169 | |
| 170 static unsigned int | |
| 171 tree_ssa_cs_elim (void) | |
| 172 { | |
| 173 return tree_ssa_phiopt_worker (true); | |
| 174 } | |
| 175 | |
| 176 /* For conditional store replacement we need a temporary to | |
| 177 put the old contents of the memory in. */ | |
| 178 static tree condstoretemp; | |
| 179 | |
| 180 /* The core routine of conditional store replacement and normal | |
| 181 phi optimizations. Both share much of the infrastructure in how | |
| 182 to match applicable basic block patterns. DO_STORE_ELIM is true | |
| 183 when we want to do conditional store replacement, false otherwise. */ | |
| 184 static unsigned int | |
| 185 tree_ssa_phiopt_worker (bool do_store_elim) | |
| 186 { | |
| 187 basic_block bb; | |
| 188 basic_block *bb_order; | |
| 189 unsigned n, i; | |
| 190 bool cfgchanged = false; | |
| 191 struct pointer_set_t *nontrap = 0; | |
| 192 | |
| 193 if (do_store_elim) | |
| 194 { | |
| 195 condstoretemp = NULL_TREE; | |
| 196 /* Calculate the set of non-trapping memory accesses. */ | |
| 197 nontrap = get_non_trapping (); | |
| 198 } | |
| 199 | |
| 200 /* Search every basic block for COND_EXPR we may be able to optimize. | |
| 201 | |
| 202 We walk the blocks in order that guarantees that a block with | |
| 203 a single predecessor is processed before the predecessor. | |
| 204 This ensures that we collapse inner ifs before visiting the | |
| 205 outer ones, and also that we do not try to visit a removed | |
| 206 block. */ | |
| 207 bb_order = blocks_in_phiopt_order (); | |
| 208 n = n_basic_blocks - NUM_FIXED_BLOCKS; | |
| 209 | |
|
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210 for (i = 0; i < n; i++) |
| 0 | 211 { |
| 212 gimple cond_stmt, phi; | |
| 213 basic_block bb1, bb2; | |
| 214 edge e1, e2; | |
| 215 tree arg0, arg1; | |
| 216 | |
| 217 bb = bb_order[i]; | |
| 218 | |
| 219 cond_stmt = last_stmt (bb); | |
| 220 /* Check to see if the last statement is a GIMPLE_COND. */ | |
| 221 if (!cond_stmt | |
| 222 || gimple_code (cond_stmt) != GIMPLE_COND) | |
| 223 continue; | |
| 224 | |
| 225 e1 = EDGE_SUCC (bb, 0); | |
| 226 bb1 = e1->dest; | |
| 227 e2 = EDGE_SUCC (bb, 1); | |
| 228 bb2 = e2->dest; | |
| 229 | |
| 230 /* We cannot do the optimization on abnormal edges. */ | |
| 231 if ((e1->flags & EDGE_ABNORMAL) != 0 | |
| 232 || (e2->flags & EDGE_ABNORMAL) != 0) | |
| 233 continue; | |
| 234 | |
| 235 /* If either bb1's succ or bb2 or bb2's succ is non NULL. */ | |
| 236 if (EDGE_COUNT (bb1->succs) == 0 | |
| 237 || bb2 == NULL | |
| 238 || EDGE_COUNT (bb2->succs) == 0) | |
| 239 continue; | |
| 240 | |
| 241 /* Find the bb which is the fall through to the other. */ | |
| 242 if (EDGE_SUCC (bb1, 0)->dest == bb2) | |
| 243 ; | |
| 244 else if (EDGE_SUCC (bb2, 0)->dest == bb1) | |
| 245 { | |
| 246 basic_block bb_tmp = bb1; | |
| 247 edge e_tmp = e1; | |
| 248 bb1 = bb2; | |
| 249 bb2 = bb_tmp; | |
| 250 e1 = e2; | |
| 251 e2 = e_tmp; | |
| 252 } | |
| 253 else | |
| 254 continue; | |
| 255 | |
| 256 e1 = EDGE_SUCC (bb1, 0); | |
| 257 | |
| 258 /* Make sure that bb1 is just a fall through. */ | |
| 259 if (!single_succ_p (bb1) | |
| 260 || (e1->flags & EDGE_FALLTHRU) == 0) | |
| 261 continue; | |
| 262 | |
| 263 /* Also make sure that bb1 only have one predecessor and that it | |
| 264 is bb. */ | |
| 265 if (!single_pred_p (bb1) | |
| 266 || single_pred (bb1) != bb) | |
| 267 continue; | |
| 268 | |
| 269 if (do_store_elim) | |
| 270 { | |
| 271 /* bb1 is the middle block, bb2 the join block, bb the split block, | |
| 272 e1 the fallthrough edge from bb1 to bb2. We can't do the | |
| 273 optimization if the join block has more than two predecessors. */ | |
| 274 if (EDGE_COUNT (bb2->preds) > 2) | |
| 275 continue; | |
| 276 if (cond_store_replacement (bb1, bb2, e1, e2, nontrap)) | |
| 277 cfgchanged = true; | |
| 278 } | |
| 279 else | |
| 280 { | |
| 281 gimple_seq phis = phi_nodes (bb2); | |
| 282 | |
| 283 /* Check to make sure that there is only one PHI node. | |
| 284 TODO: we could do it with more than one iff the other PHI nodes | |
| 285 have the same elements for these two edges. */ | |
| 286 if (! gimple_seq_singleton_p (phis)) | |
| 287 continue; | |
| 288 | |
| 289 phi = gsi_stmt (gsi_start (phis)); | |
| 290 arg0 = gimple_phi_arg_def (phi, e1->dest_idx); | |
| 291 arg1 = gimple_phi_arg_def (phi, e2->dest_idx); | |
| 292 | |
| 293 /* Something is wrong if we cannot find the arguments in the PHI | |
| 294 node. */ | |
| 295 gcc_assert (arg0 != NULL && arg1 != NULL); | |
| 296 | |
| 297 /* Do the replacement of conditional if it can be done. */ | |
| 298 if (conditional_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
| 299 cfgchanged = true; | |
| 300 else if (value_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
| 301 cfgchanged = true; | |
| 302 else if (abs_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
| 303 cfgchanged = true; | |
| 304 else if (minmax_replacement (bb, bb1, e1, e2, phi, arg0, arg1)) | |
| 305 cfgchanged = true; | |
| 306 } | |
| 307 } | |
| 308 | |
| 309 free (bb_order); | |
|
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310 |
| 0 | 311 if (do_store_elim) |
| 312 pointer_set_destroy (nontrap); | |
| 313 /* If the CFG has changed, we should cleanup the CFG. */ | |
| 314 if (cfgchanged && do_store_elim) | |
| 315 { | |
| 316 /* In cond-store replacement we have added some loads on edges | |
| 317 and new VOPS (as we moved the store, and created a load). */ | |
| 318 gsi_commit_edge_inserts (); | |
| 319 return TODO_cleanup_cfg | TODO_update_ssa_only_virtuals; | |
| 320 } | |
| 321 else if (cfgchanged) | |
| 322 return TODO_cleanup_cfg; | |
| 323 return 0; | |
| 324 } | |
| 325 | |
| 326 /* Returns the list of basic blocks in the function in an order that guarantees | |
| 327 that if a block X has just a single predecessor Y, then Y is after X in the | |
| 328 ordering. */ | |
| 329 | |
| 330 basic_block * | |
| 331 blocks_in_phiopt_order (void) | |
| 332 { | |
| 333 basic_block x, y; | |
| 334 basic_block *order = XNEWVEC (basic_block, n_basic_blocks); | |
|
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335 unsigned n = n_basic_blocks - NUM_FIXED_BLOCKS; |
| 0 | 336 unsigned np, i; |
|
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337 sbitmap visited = sbitmap_alloc (last_basic_block); |
| 0 | 338 |
|
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339 #define MARK_VISITED(BB) (SET_BIT (visited, (BB)->index)) |
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340 #define VISITED_P(BB) (TEST_BIT (visited, (BB)->index)) |
| 0 | 341 |
| 342 sbitmap_zero (visited); | |
| 343 | |
| 344 MARK_VISITED (ENTRY_BLOCK_PTR); | |
| 345 FOR_EACH_BB (x) | |
| 346 { | |
| 347 if (VISITED_P (x)) | |
| 348 continue; | |
| 349 | |
| 350 /* Walk the predecessors of x as long as they have precisely one | |
| 351 predecessor and add them to the list, so that they get stored | |
| 352 after x. */ | |
| 353 for (y = x, np = 1; | |
| 354 single_pred_p (y) && !VISITED_P (single_pred (y)); | |
| 355 y = single_pred (y)) | |
| 356 np++; | |
| 357 for (y = x, i = n - np; | |
| 358 single_pred_p (y) && !VISITED_P (single_pred (y)); | |
| 359 y = single_pred (y), i++) | |
| 360 { | |
| 361 order[i] = y; | |
| 362 MARK_VISITED (y); | |
| 363 } | |
| 364 order[i] = y; | |
| 365 MARK_VISITED (y); | |
| 366 | |
| 367 gcc_assert (i == n - 1); | |
| 368 n -= np; | |
| 369 } | |
| 370 | |
| 371 sbitmap_free (visited); | |
| 372 gcc_assert (n == 0); | |
| 373 return order; | |
| 374 | |
| 375 #undef MARK_VISITED | |
| 376 #undef VISITED_P | |
| 377 } | |
| 378 | |
| 379 | |
| 380 /* Return TRUE if block BB has no executable statements, otherwise return | |
| 381 FALSE. */ | |
| 382 | |
| 383 bool | |
| 384 empty_block_p (basic_block bb) | |
| 385 { | |
| 386 /* BB must have no executable statements. */ | |
|
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387 gimple_stmt_iterator gsi = gsi_after_labels (bb); |
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388 if (gsi_end_p (gsi)) |
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389 return true; |
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390 if (is_gimple_debug (gsi_stmt (gsi))) |
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391 gsi_next_nondebug (&gsi); |
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392 return gsi_end_p (gsi); |
| 0 | 393 } |
| 394 | |
| 395 /* Replace PHI node element whose edge is E in block BB with variable NEW. | |
| 396 Remove the edge from COND_BLOCK which does not lead to BB (COND_BLOCK | |
| 397 is known to have two edges, one of which must reach BB). */ | |
| 398 | |
| 399 static void | |
| 400 replace_phi_edge_with_variable (basic_block cond_block, | |
| 401 edge e, gimple phi, tree new_tree) | |
| 402 { | |
| 403 basic_block bb = gimple_bb (phi); | |
| 404 basic_block block_to_remove; | |
| 405 gimple_stmt_iterator gsi; | |
| 406 | |
| 407 /* Change the PHI argument to new. */ | |
| 408 SET_USE (PHI_ARG_DEF_PTR (phi, e->dest_idx), new_tree); | |
| 409 | |
| 410 /* Remove the empty basic block. */ | |
| 411 if (EDGE_SUCC (cond_block, 0)->dest == bb) | |
| 412 { | |
| 413 EDGE_SUCC (cond_block, 0)->flags |= EDGE_FALLTHRU; | |
| 414 EDGE_SUCC (cond_block, 0)->flags &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); | |
| 415 EDGE_SUCC (cond_block, 0)->probability = REG_BR_PROB_BASE; | |
| 416 EDGE_SUCC (cond_block, 0)->count += EDGE_SUCC (cond_block, 1)->count; | |
| 417 | |
| 418 block_to_remove = EDGE_SUCC (cond_block, 1)->dest; | |
| 419 } | |
| 420 else | |
| 421 { | |
| 422 EDGE_SUCC (cond_block, 1)->flags |= EDGE_FALLTHRU; | |
| 423 EDGE_SUCC (cond_block, 1)->flags | |
| 424 &= ~(EDGE_TRUE_VALUE | EDGE_FALSE_VALUE); | |
| 425 EDGE_SUCC (cond_block, 1)->probability = REG_BR_PROB_BASE; | |
| 426 EDGE_SUCC (cond_block, 1)->count += EDGE_SUCC (cond_block, 0)->count; | |
| 427 | |
| 428 block_to_remove = EDGE_SUCC (cond_block, 0)->dest; | |
| 429 } | |
| 430 delete_basic_block (block_to_remove); | |
| 431 | |
| 432 /* Eliminate the COND_EXPR at the end of COND_BLOCK. */ | |
| 433 gsi = gsi_last_bb (cond_block); | |
| 434 gsi_remove (&gsi, true); | |
| 435 | |
| 436 if (dump_file && (dump_flags & TDF_DETAILS)) | |
| 437 fprintf (dump_file, | |
| 438 "COND_EXPR in block %d and PHI in block %d converted to straightline code.\n", | |
| 439 cond_block->index, | |
| 440 bb->index); | |
| 441 } | |
| 442 | |
| 443 /* The function conditional_replacement does the main work of doing the | |
| 444 conditional replacement. Return true if the replacement is done. | |
| 445 Otherwise return false. | |
| 446 BB is the basic block where the replacement is going to be done on. ARG0 | |
| 447 is argument 0 from PHI. Likewise for ARG1. */ | |
| 448 | |
| 449 static bool | |
| 450 conditional_replacement (basic_block cond_bb, basic_block middle_bb, | |
| 451 edge e0, edge e1, gimple phi, | |
| 452 tree arg0, tree arg1) | |
| 453 { | |
| 454 tree result; | |
| 455 gimple stmt, new_stmt; | |
| 456 tree cond; | |
| 457 gimple_stmt_iterator gsi; | |
| 458 edge true_edge, false_edge; | |
| 459 tree new_var, new_var2; | |
| 460 | |
| 461 /* FIXME: Gimplification of complex type is too hard for now. */ | |
| 462 if (TREE_CODE (TREE_TYPE (arg0)) == COMPLEX_TYPE | |
| 463 || TREE_CODE (TREE_TYPE (arg1)) == COMPLEX_TYPE) | |
| 464 return false; | |
| 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; | |
| 473 | |
| 474 if (!empty_block_p (middle_bb)) | |
| 475 return false; | |
| 476 | |
| 477 /* At this point we know we have a GIMPLE_COND with two successors. | |
| 478 One successor is BB, the other successor is an empty block which | |
| 479 falls through into BB. | |
| 480 | |
| 481 There is a single PHI node at the join point (BB) and its arguments | |
| 482 are constants (0, 1). | |
| 483 | |
| 484 So, given the condition COND, and the two PHI arguments, we can | |
| 485 rewrite this PHI into non-branching code: | |
| 486 | |
| 487 dest = (COND) or dest = COND' | |
| 488 | |
| 489 We use the condition as-is if the argument associated with the | |
| 490 true edge has the value one or the argument associated with the | |
| 491 false edge as the value zero. Note that those conditions are not | |
| 492 the same since only one of the outgoing edges from the GIMPLE_COND | |
| 493 will directly reach BB and thus be associated with an argument. */ | |
| 494 | |
| 495 stmt = last_stmt (cond_bb); | |
| 496 result = PHI_RESULT (phi); | |
| 497 | |
| 498 /* To handle special cases like floating point comparison, it is easier and | |
| 499 less error-prone to build a tree and gimplify it on the fly though it is | |
| 500 less efficient. */ | |
| 501 cond = fold_build2 (gimple_cond_code (stmt), boolean_type_node, | |
| 502 gimple_cond_lhs (stmt), gimple_cond_rhs (stmt)); | |
| 503 | |
| 504 /* We need to know which is the true edge and which is the false | |
| 505 edge so that we know when to invert the condition below. */ | |
| 506 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); | |
| 507 if ((e0 == true_edge && integer_zerop (arg0)) | |
| 508 || (e0 == false_edge && integer_onep (arg0)) | |
| 509 || (e1 == true_edge && integer_zerop (arg1)) | |
| 510 || (e1 == false_edge && integer_onep (arg1))) | |
| 511 cond = fold_build1 (TRUTH_NOT_EXPR, TREE_TYPE (cond), cond); | |
| 512 | |
| 513 /* Insert our new statements at the end of conditional block before the | |
| 514 COND_STMT. */ | |
| 515 gsi = gsi_for_stmt (stmt); | |
| 516 new_var = force_gimple_operand_gsi (&gsi, cond, true, NULL, true, | |
| 517 GSI_SAME_STMT); | |
| 518 | |
| 519 if (!useless_type_conversion_p (TREE_TYPE (result), TREE_TYPE (new_var))) | |
| 520 { | |
|
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521 source_location locus_0, locus_1; |
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522 |
| 0 | 523 new_var2 = create_tmp_var (TREE_TYPE (result), NULL); |
| 524 add_referenced_var (new_var2); | |
| 525 new_stmt = gimple_build_assign_with_ops (CONVERT_EXPR, new_var2, | |
| 526 new_var, NULL); | |
| 527 new_var2 = make_ssa_name (new_var2, new_stmt); | |
| 528 gimple_assign_set_lhs (new_stmt, new_var2); | |
| 529 gsi_insert_before (&gsi, new_stmt, GSI_SAME_STMT); | |
| 530 new_var = new_var2; | |
|
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531 |
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532 /* Set the locus to the first argument, unless is doesn't have one. */ |
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533 locus_0 = gimple_phi_arg_location (phi, 0); |
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534 locus_1 = gimple_phi_arg_location (phi, 1); |
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535 if (locus_0 == UNKNOWN_LOCATION) |
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536 locus_0 = locus_1; |
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537 gimple_set_location (new_stmt, locus_0); |
| 0 | 538 } |
| 539 | |
| 540 replace_phi_edge_with_variable (cond_bb, e1, phi, new_var); | |
| 541 | |
| 542 /* Note that we optimized this PHI. */ | |
| 543 return true; | |
| 544 } | |
| 545 | |
| 546 /* The function value_replacement does the main work of doing the value | |
| 547 replacement. Return true if the replacement is done. Otherwise return | |
| 548 false. | |
| 549 BB is the basic block where the replacement is going to be done on. ARG0 | |
| 550 is argument 0 from the PHI. Likewise for ARG1. */ | |
| 551 | |
| 552 static bool | |
| 553 value_replacement (basic_block cond_bb, basic_block middle_bb, | |
| 554 edge e0, edge e1, gimple phi, | |
| 555 tree arg0, tree arg1) | |
| 556 { | |
| 557 gimple cond; | |
| 558 edge true_edge, false_edge; | |
| 559 enum tree_code code; | |
| 560 | |
| 561 /* If the type says honor signed zeros we cannot do this | |
| 562 optimization. */ | |
| 563 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) | |
| 564 return false; | |
| 565 | |
| 566 if (!empty_block_p (middle_bb)) | |
| 567 return false; | |
| 568 | |
| 569 cond = last_stmt (cond_bb); | |
| 570 code = gimple_cond_code (cond); | |
| 571 | |
| 572 /* This transformation is only valid for equality comparisons. */ | |
| 573 if (code != NE_EXPR && code != EQ_EXPR) | |
| 574 return false; | |
| 575 | |
| 576 /* We need to know which is the true edge and which is the false | |
| 577 edge so that we know if have abs or negative abs. */ | |
| 578 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); | |
| 579 | |
| 580 /* At this point we know we have a COND_EXPR with two successors. | |
| 581 One successor is BB, the other successor is an empty block which | |
| 582 falls through into BB. | |
| 583 | |
| 584 The condition for the COND_EXPR is known to be NE_EXPR or EQ_EXPR. | |
| 585 | |
| 586 There is a single PHI node at the join point (BB) with two arguments. | |
| 587 | |
| 588 We now need to verify that the two arguments in the PHI node match | |
| 589 the two arguments to the equality comparison. */ | |
| 590 | |
| 591 if ((operand_equal_for_phi_arg_p (arg0, gimple_cond_lhs (cond)) | |
| 592 && operand_equal_for_phi_arg_p (arg1, gimple_cond_rhs (cond))) | |
| 593 || (operand_equal_for_phi_arg_p (arg1, gimple_cond_lhs (cond)) | |
| 594 && operand_equal_for_phi_arg_p (arg0, gimple_cond_rhs (cond)))) | |
| 595 { | |
| 596 edge e; | |
| 597 tree arg; | |
| 598 | |
| 599 /* For NE_EXPR, we want to build an assignment result = arg where | |
| 600 arg is the PHI argument associated with the true edge. For | |
| 601 EQ_EXPR we want the PHI argument associated with the false edge. */ | |
| 602 e = (code == NE_EXPR ? true_edge : false_edge); | |
| 603 | |
| 604 /* Unfortunately, E may not reach BB (it may instead have gone to | |
| 605 OTHER_BLOCK). If that is the case, then we want the single outgoing | |
| 606 edge from OTHER_BLOCK which reaches BB and represents the desired | |
| 607 path from COND_BLOCK. */ | |
| 608 if (e->dest == middle_bb) | |
| 609 e = single_succ_edge (e->dest); | |
| 610 | |
| 611 /* Now we know the incoming edge to BB that has the argument for the | |
| 612 RHS of our new assignment statement. */ | |
| 613 if (e0 == e) | |
| 614 arg = arg0; | |
| 615 else | |
| 616 arg = arg1; | |
| 617 | |
| 618 replace_phi_edge_with_variable (cond_bb, e1, phi, arg); | |
| 619 | |
| 620 /* Note that we optimized this PHI. */ | |
| 621 return true; | |
| 622 } | |
| 623 return false; | |
| 624 } | |
| 625 | |
| 626 /* The function minmax_replacement does the main work of doing the minmax | |
| 627 replacement. Return true if the replacement is done. Otherwise return | |
| 628 false. | |
| 629 BB is the basic block where the replacement is going to be done on. ARG0 | |
| 630 is argument 0 from the PHI. Likewise for ARG1. */ | |
| 631 | |
| 632 static bool | |
| 633 minmax_replacement (basic_block cond_bb, basic_block middle_bb, | |
| 634 edge e0, edge e1, gimple phi, | |
| 635 tree arg0, tree arg1) | |
| 636 { | |
| 637 tree result, type; | |
| 638 gimple cond, new_stmt; | |
| 639 edge true_edge, false_edge; | |
| 640 enum tree_code cmp, minmax, ass_code; | |
| 641 tree smaller, larger, arg_true, arg_false; | |
| 642 gimple_stmt_iterator gsi, gsi_from; | |
| 643 | |
| 644 type = TREE_TYPE (PHI_RESULT (phi)); | |
| 645 | |
| 646 /* The optimization may be unsafe due to NaNs. */ | |
| 647 if (HONOR_NANS (TYPE_MODE (type))) | |
| 648 return false; | |
| 649 | |
| 650 cond = last_stmt (cond_bb); | |
| 651 cmp = gimple_cond_code (cond); | |
| 652 result = PHI_RESULT (phi); | |
| 653 | |
| 654 /* This transformation is only valid for order comparisons. Record which | |
| 655 operand is smaller/larger if the result of the comparison is true. */ | |
| 656 if (cmp == LT_EXPR || cmp == LE_EXPR) | |
| 657 { | |
| 658 smaller = gimple_cond_lhs (cond); | |
| 659 larger = gimple_cond_rhs (cond); | |
| 660 } | |
| 661 else if (cmp == GT_EXPR || cmp == GE_EXPR) | |
| 662 { | |
| 663 smaller = gimple_cond_rhs (cond); | |
| 664 larger = gimple_cond_lhs (cond); | |
| 665 } | |
| 666 else | |
| 667 return false; | |
| 668 | |
| 669 /* We need to know which is the true edge and which is the false | |
| 670 edge so that we know if have abs or negative abs. */ | |
| 671 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); | |
| 672 | |
| 673 /* Forward the edges over the middle basic block. */ | |
| 674 if (true_edge->dest == middle_bb) | |
| 675 true_edge = EDGE_SUCC (true_edge->dest, 0); | |
| 676 if (false_edge->dest == middle_bb) | |
| 677 false_edge = EDGE_SUCC (false_edge->dest, 0); | |
| 678 | |
| 679 if (true_edge == e0) | |
| 680 { | |
| 681 gcc_assert (false_edge == e1); | |
| 682 arg_true = arg0; | |
| 683 arg_false = arg1; | |
| 684 } | |
| 685 else | |
| 686 { | |
| 687 gcc_assert (false_edge == e0); | |
| 688 gcc_assert (true_edge == e1); | |
| 689 arg_true = arg1; | |
| 690 arg_false = arg0; | |
| 691 } | |
| 692 | |
| 693 if (empty_block_p (middle_bb)) | |
| 694 { | |
| 695 if (operand_equal_for_phi_arg_p (arg_true, smaller) | |
| 696 && operand_equal_for_phi_arg_p (arg_false, larger)) | |
| 697 { | |
| 698 /* Case | |
|
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699 |
| 0 | 700 if (smaller < larger) |
| 701 rslt = smaller; | |
| 702 else | |
| 703 rslt = larger; */ | |
| 704 minmax = MIN_EXPR; | |
| 705 } | |
| 706 else if (operand_equal_for_phi_arg_p (arg_false, smaller) | |
| 707 && operand_equal_for_phi_arg_p (arg_true, larger)) | |
| 708 minmax = MAX_EXPR; | |
| 709 else | |
| 710 return false; | |
| 711 } | |
| 712 else | |
| 713 { | |
| 714 /* Recognize the following case, assuming d <= u: | |
| 715 | |
| 716 if (a <= u) | |
| 717 b = MAX (a, d); | |
| 718 x = PHI <b, u> | |
| 719 | |
| 720 This is equivalent to | |
| 721 | |
| 722 b = MAX (a, d); | |
| 723 x = MIN (b, u); */ | |
| 724 | |
| 725 gimple assign = last_and_only_stmt (middle_bb); | |
| 726 tree lhs, op0, op1, bound; | |
| 727 | |
| 728 if (!assign | |
| 729 || gimple_code (assign) != GIMPLE_ASSIGN) | |
| 730 return false; | |
| 731 | |
| 732 lhs = gimple_assign_lhs (assign); | |
| 733 ass_code = gimple_assign_rhs_code (assign); | |
| 734 if (ass_code != MAX_EXPR && ass_code != MIN_EXPR) | |
| 735 return false; | |
| 736 op0 = gimple_assign_rhs1 (assign); | |
| 737 op1 = gimple_assign_rhs2 (assign); | |
| 738 | |
| 739 if (true_edge->src == middle_bb) | |
| 740 { | |
| 741 /* We got here if the condition is true, i.e., SMALLER < LARGER. */ | |
| 742 if (!operand_equal_for_phi_arg_p (lhs, arg_true)) | |
| 743 return false; | |
| 744 | |
| 745 if (operand_equal_for_phi_arg_p (arg_false, larger)) | |
| 746 { | |
| 747 /* Case | |
| 748 | |
| 749 if (smaller < larger) | |
| 750 { | |
| 751 r' = MAX_EXPR (smaller, bound) | |
| 752 } | |
| 753 r = PHI <r', larger> --> to be turned to MIN_EXPR. */ | |
| 754 if (ass_code != MAX_EXPR) | |
| 755 return false; | |
| 756 | |
| 757 minmax = MIN_EXPR; | |
| 758 if (operand_equal_for_phi_arg_p (op0, smaller)) | |
| 759 bound = op1; | |
| 760 else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
| 761 bound = op0; | |
| 762 else | |
| 763 return false; | |
| 764 | |
| 765 /* We need BOUND <= LARGER. */ | |
| 766 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, | |
| 767 bound, larger))) | |
| 768 return false; | |
| 769 } | |
| 770 else if (operand_equal_for_phi_arg_p (arg_false, smaller)) | |
| 771 { | |
| 772 /* Case | |
| 773 | |
| 774 if (smaller < larger) | |
| 775 { | |
| 776 r' = MIN_EXPR (larger, bound) | |
| 777 } | |
| 778 r = PHI <r', smaller> --> to be turned to MAX_EXPR. */ | |
| 779 if (ass_code != MIN_EXPR) | |
| 780 return false; | |
| 781 | |
| 782 minmax = MAX_EXPR; | |
| 783 if (operand_equal_for_phi_arg_p (op0, larger)) | |
| 784 bound = op1; | |
| 785 else if (operand_equal_for_phi_arg_p (op1, larger)) | |
| 786 bound = op0; | |
| 787 else | |
| 788 return false; | |
| 789 | |
| 790 /* We need BOUND >= SMALLER. */ | |
| 791 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, | |
| 792 bound, smaller))) | |
| 793 return false; | |
| 794 } | |
| 795 else | |
| 796 return false; | |
| 797 } | |
| 798 else | |
| 799 { | |
| 800 /* We got here if the condition is false, i.e., SMALLER > LARGER. */ | |
| 801 if (!operand_equal_for_phi_arg_p (lhs, arg_false)) | |
| 802 return false; | |
| 803 | |
| 804 if (operand_equal_for_phi_arg_p (arg_true, larger)) | |
| 805 { | |
| 806 /* Case | |
| 807 | |
| 808 if (smaller > larger) | |
| 809 { | |
| 810 r' = MIN_EXPR (smaller, bound) | |
| 811 } | |
| 812 r = PHI <r', larger> --> to be turned to MAX_EXPR. */ | |
| 813 if (ass_code != MIN_EXPR) | |
| 814 return false; | |
| 815 | |
| 816 minmax = MAX_EXPR; | |
| 817 if (operand_equal_for_phi_arg_p (op0, smaller)) | |
| 818 bound = op1; | |
| 819 else if (operand_equal_for_phi_arg_p (op1, smaller)) | |
| 820 bound = op0; | |
| 821 else | |
| 822 return false; | |
| 823 | |
| 824 /* We need BOUND >= LARGER. */ | |
| 825 if (!integer_nonzerop (fold_build2 (GE_EXPR, boolean_type_node, | |
| 826 bound, larger))) | |
| 827 return false; | |
| 828 } | |
| 829 else if (operand_equal_for_phi_arg_p (arg_true, smaller)) | |
| 830 { | |
| 831 /* Case | |
| 832 | |
| 833 if (smaller > larger) | |
| 834 { | |
| 835 r' = MAX_EXPR (larger, bound) | |
| 836 } | |
| 837 r = PHI <r', smaller> --> to be turned to MIN_EXPR. */ | |
| 838 if (ass_code != MAX_EXPR) | |
| 839 return false; | |
| 840 | |
| 841 minmax = MIN_EXPR; | |
| 842 if (operand_equal_for_phi_arg_p (op0, larger)) | |
| 843 bound = op1; | |
| 844 else if (operand_equal_for_phi_arg_p (op1, larger)) | |
| 845 bound = op0; | |
| 846 else | |
| 847 return false; | |
| 848 | |
| 849 /* We need BOUND <= SMALLER. */ | |
| 850 if (!integer_nonzerop (fold_build2 (LE_EXPR, boolean_type_node, | |
| 851 bound, smaller))) | |
| 852 return false; | |
| 853 } | |
| 854 else | |
| 855 return false; | |
| 856 } | |
| 857 | |
| 858 /* Move the statement from the middle block. */ | |
| 859 gsi = gsi_last_bb (cond_bb); | |
|
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860 gsi_from = gsi_last_nondebug_bb (middle_bb); |
| 0 | 861 gsi_move_before (&gsi_from, &gsi); |
| 862 } | |
| 863 | |
| 864 /* Emit the statement to compute min/max. */ | |
| 865 result = duplicate_ssa_name (PHI_RESULT (phi), NULL); | |
| 866 new_stmt = gimple_build_assign_with_ops (minmax, result, arg0, arg1); | |
| 867 gsi = gsi_last_bb (cond_bb); | |
| 868 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); | |
| 869 | |
| 870 replace_phi_edge_with_variable (cond_bb, e1, phi, result); | |
| 871 return true; | |
| 872 } | |
| 873 | |
| 874 /* The function absolute_replacement does the main work of doing the absolute | |
| 875 replacement. Return true if the replacement is done. Otherwise return | |
| 876 false. | |
| 877 bb is the basic block where the replacement is going to be done on. arg0 | |
| 878 is argument 0 from the phi. Likewise for arg1. */ | |
| 879 | |
| 880 static bool | |
| 881 abs_replacement (basic_block cond_bb, basic_block middle_bb, | |
| 882 edge e0 ATTRIBUTE_UNUSED, edge e1, | |
| 883 gimple phi, tree arg0, tree arg1) | |
| 884 { | |
| 885 tree result; | |
| 886 gimple new_stmt, cond; | |
| 887 gimple_stmt_iterator gsi; | |
| 888 edge true_edge, false_edge; | |
| 889 gimple assign; | |
| 890 edge e; | |
| 891 tree rhs, lhs; | |
| 892 bool negate; | |
| 893 enum tree_code cond_code; | |
| 894 | |
| 895 /* If the type says honor signed zeros we cannot do this | |
| 896 optimization. */ | |
| 897 if (HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (arg1)))) | |
| 898 return false; | |
| 899 | |
| 900 /* OTHER_BLOCK must have only one executable statement which must have the | |
| 901 form arg0 = -arg1 or arg1 = -arg0. */ | |
| 902 | |
| 903 assign = last_and_only_stmt (middle_bb); | |
| 904 /* If we did not find the proper negation assignment, then we can not | |
| 905 optimize. */ | |
| 906 if (assign == NULL) | |
| 907 return false; | |
|
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908 |
| 0 | 909 /* If we got here, then we have found the only executable statement |
| 910 in OTHER_BLOCK. If it is anything other than arg = -arg1 or | |
| 911 arg1 = -arg0, then we can not optimize. */ | |
| 912 if (gimple_code (assign) != GIMPLE_ASSIGN) | |
| 913 return false; | |
| 914 | |
| 915 lhs = gimple_assign_lhs (assign); | |
| 916 | |
| 917 if (gimple_assign_rhs_code (assign) != NEGATE_EXPR) | |
| 918 return false; | |
| 919 | |
| 920 rhs = gimple_assign_rhs1 (assign); | |
|
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921 |
| 0 | 922 /* The assignment has to be arg0 = -arg1 or arg1 = -arg0. */ |
| 923 if (!(lhs == arg0 && rhs == arg1) | |
| 924 && !(lhs == arg1 && rhs == arg0)) | |
| 925 return false; | |
| 926 | |
| 927 cond = last_stmt (cond_bb); | |
| 928 result = PHI_RESULT (phi); | |
| 929 | |
| 930 /* Only relationals comparing arg[01] against zero are interesting. */ | |
| 931 cond_code = gimple_cond_code (cond); | |
| 932 if (cond_code != GT_EXPR && cond_code != GE_EXPR | |
| 933 && cond_code != LT_EXPR && cond_code != LE_EXPR) | |
| 934 return false; | |
| 935 | |
| 936 /* Make sure the conditional is arg[01] OP y. */ | |
| 937 if (gimple_cond_lhs (cond) != rhs) | |
| 938 return false; | |
| 939 | |
| 940 if (FLOAT_TYPE_P (TREE_TYPE (gimple_cond_rhs (cond))) | |
| 941 ? real_zerop (gimple_cond_rhs (cond)) | |
| 942 : integer_zerop (gimple_cond_rhs (cond))) | |
| 943 ; | |
| 944 else | |
| 945 return false; | |
| 946 | |
| 947 /* We need to know which is the true edge and which is the false | |
| 948 edge so that we know if have abs or negative abs. */ | |
| 949 extract_true_false_edges_from_block (cond_bb, &true_edge, &false_edge); | |
| 950 | |
| 951 /* For GT_EXPR/GE_EXPR, if the true edge goes to OTHER_BLOCK, then we | |
| 952 will need to negate the result. Similarly for LT_EXPR/LE_EXPR if | |
| 953 the false edge goes to OTHER_BLOCK. */ | |
| 954 if (cond_code == GT_EXPR || cond_code == GE_EXPR) | |
| 955 e = true_edge; | |
| 956 else | |
| 957 e = false_edge; | |
| 958 | |
| 959 if (e->dest == middle_bb) | |
| 960 negate = true; | |
| 961 else | |
| 962 negate = false; | |
| 963 | |
| 964 result = duplicate_ssa_name (result, NULL); | |
| 965 | |
| 966 if (negate) | |
| 967 { | |
| 968 tree tmp = create_tmp_var (TREE_TYPE (result), NULL); | |
| 969 add_referenced_var (tmp); | |
| 970 lhs = make_ssa_name (tmp, NULL); | |
| 971 } | |
| 972 else | |
| 973 lhs = result; | |
| 974 | |
| 975 /* Build the modify expression with abs expression. */ | |
| 976 new_stmt = gimple_build_assign_with_ops (ABS_EXPR, lhs, rhs, NULL); | |
| 977 | |
| 978 gsi = gsi_last_bb (cond_bb); | |
| 979 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); | |
| 980 | |
| 981 if (negate) | |
| 982 { | |
| 983 /* Get the right GSI. We want to insert after the recently | |
| 984 added ABS_EXPR statement (which we know is the first statement | |
| 985 in the block. */ | |
| 986 new_stmt = gimple_build_assign_with_ops (NEGATE_EXPR, result, lhs, NULL); | |
| 987 | |
| 988 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT); | |
| 989 } | |
| 990 | |
| 991 replace_phi_edge_with_variable (cond_bb, e1, phi, result); | |
| 992 | |
| 993 /* Note that we optimized this PHI. */ | |
| 994 return true; | |
| 995 } | |
| 996 | |
| 997 /* Auxiliary functions to determine the set of memory accesses which | |
| 998 can't trap because they are preceded by accesses to the same memory | |
| 999 portion. We do that for INDIRECT_REFs, so we only need to track | |
| 1000 the SSA_NAME of the pointer indirectly referenced. The algorithm | |
| 1001 simply is a walk over all instructions in dominator order. When | |
| 1002 we see an INDIRECT_REF we determine if we've already seen a same | |
| 1003 ref anywhere up to the root of the dominator tree. If we do the | |
| 1004 current access can't trap. If we don't see any dominating access | |
| 1005 the current access might trap, but might also make later accesses | |
| 1006 non-trapping, so we remember it. We need to be careful with loads | |
| 1007 or stores, for instance a load might not trap, while a store would, | |
| 1008 so if we see a dominating read access this doesn't mean that a later | |
| 1009 write access would not trap. Hence we also need to differentiate the | |
| 1010 type of access(es) seen. | |
| 1011 | |
| 1012 ??? We currently are very conservative and assume that a load might | |
| 1013 trap even if a store doesn't (write-only memory). This probably is | |
| 1014 overly conservative. */ | |
| 1015 | |
| 1016 /* A hash-table of SSA_NAMEs, and in which basic block an INDIRECT_REF | |
| 1017 through it was seen, which would constitute a no-trap region for | |
| 1018 same accesses. */ | |
| 1019 struct name_to_bb | |
| 1020 { | |
| 1021 tree ssa_name; | |
| 1022 basic_block bb; | |
| 1023 unsigned store : 1; | |
| 1024 }; | |
| 1025 | |
| 1026 /* The hash table for remembering what we've seen. */ | |
| 1027 static htab_t seen_ssa_names; | |
| 1028 | |
| 1029 /* The set of INDIRECT_REFs which can't trap. */ | |
| 1030 static struct pointer_set_t *nontrap_set; | |
| 1031 | |
| 1032 /* The hash function, based on the pointer to the pointer SSA_NAME. */ | |
| 1033 static hashval_t | |
| 1034 name_to_bb_hash (const void *p) | |
| 1035 { | |
| 1036 const_tree n = ((const struct name_to_bb *)p)->ssa_name; | |
| 1037 return htab_hash_pointer (n) ^ ((const struct name_to_bb *)p)->store; | |
| 1038 } | |
| 1039 | |
| 1040 /* The equality function of *P1 and *P2. SSA_NAMEs are shared, so | |
| 1041 it's enough to simply compare them for equality. */ | |
| 1042 static int | |
| 1043 name_to_bb_eq (const void *p1, const void *p2) | |
| 1044 { | |
| 1045 const struct name_to_bb *n1 = (const struct name_to_bb *)p1; | |
| 1046 const struct name_to_bb *n2 = (const struct name_to_bb *)p2; | |
| 1047 | |
| 1048 return n1->ssa_name == n2->ssa_name && n1->store == n2->store; | |
| 1049 } | |
| 1050 | |
| 1051 /* We see the expression EXP in basic block BB. If it's an interesting | |
| 1052 expression (an INDIRECT_REF through an SSA_NAME) possibly insert the | |
| 1053 expression into the set NONTRAP or the hash table of seen expressions. | |
| 1054 STORE is true if this expression is on the LHS, otherwise it's on | |
| 1055 the RHS. */ | |
| 1056 static void | |
| 1057 add_or_mark_expr (basic_block bb, tree exp, | |
| 1058 struct pointer_set_t *nontrap, bool store) | |
| 1059 { | |
| 1060 if (INDIRECT_REF_P (exp) | |
| 1061 && TREE_CODE (TREE_OPERAND (exp, 0)) == SSA_NAME) | |
| 1062 { | |
| 1063 tree name = TREE_OPERAND (exp, 0); | |
| 1064 struct name_to_bb map; | |
| 1065 void **slot; | |
| 1066 struct name_to_bb *n2bb; | |
| 1067 basic_block found_bb = 0; | |
| 1068 | |
| 1069 /* Try to find the last seen INDIRECT_REF through the same | |
| 1070 SSA_NAME, which can trap. */ | |
| 1071 map.ssa_name = name; | |
| 1072 map.bb = 0; | |
| 1073 map.store = store; | |
| 1074 slot = htab_find_slot (seen_ssa_names, &map, INSERT); | |
| 1075 n2bb = (struct name_to_bb *) *slot; | |
| 1076 if (n2bb) | |
| 1077 found_bb = n2bb->bb; | |
| 1078 | |
| 1079 /* If we've found a trapping INDIRECT_REF, _and_ it dominates EXP | |
| 1080 (it's in a basic block on the path from us to the dominator root) | |
| 1081 then we can't trap. */ | |
| 1082 if (found_bb && found_bb->aux == (void *)1) | |
| 1083 { | |
| 1084 pointer_set_insert (nontrap, exp); | |
| 1085 } | |
| 1086 else | |
| 1087 { | |
| 1088 /* EXP might trap, so insert it into the hash table. */ | |
| 1089 if (n2bb) | |
| 1090 { | |
| 1091 n2bb->bb = bb; | |
| 1092 } | |
| 1093 else | |
| 1094 { | |
| 1095 n2bb = XNEW (struct name_to_bb); | |
| 1096 n2bb->ssa_name = name; | |
| 1097 n2bb->bb = bb; | |
| 1098 n2bb->store = store; | |
| 1099 *slot = n2bb; | |
| 1100 } | |
| 1101 } | |
| 1102 } | |
| 1103 } | |
| 1104 | |
| 1105 /* Called by walk_dominator_tree, when entering the block BB. */ | |
| 1106 static void | |
| 1107 nt_init_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb) | |
| 1108 { | |
| 1109 gimple_stmt_iterator gsi; | |
| 1110 /* Mark this BB as being on the path to dominator root. */ | |
| 1111 bb->aux = (void*)1; | |
| 1112 | |
| 1113 /* And walk the statements in order. */ | |
| 1114 for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi)) | |
| 1115 { | |
| 1116 gimple stmt = gsi_stmt (gsi); | |
| 1117 | |
| 1118 if (is_gimple_assign (stmt)) | |
| 1119 { | |
| 1120 add_or_mark_expr (bb, gimple_assign_lhs (stmt), nontrap_set, true); | |
| 1121 add_or_mark_expr (bb, gimple_assign_rhs1 (stmt), nontrap_set, false); | |
| 1122 if (get_gimple_rhs_num_ops (gimple_assign_rhs_code (stmt)) > 1) | |
| 1123 add_or_mark_expr (bb, gimple_assign_rhs2 (stmt), nontrap_set, | |
| 1124 false); | |
| 1125 } | |
| 1126 } | |
| 1127 } | |
| 1128 | |
| 1129 /* Called by walk_dominator_tree, when basic block BB is exited. */ | |
| 1130 static void | |
| 1131 nt_fini_block (struct dom_walk_data *data ATTRIBUTE_UNUSED, basic_block bb) | |
| 1132 { | |
| 1133 /* This BB isn't on the path to dominator root anymore. */ | |
| 1134 bb->aux = NULL; | |
| 1135 } | |
| 1136 | |
| 1137 /* This is the entry point of gathering non trapping memory accesses. | |
| 1138 It will do a dominator walk over the whole function, and it will | |
| 1139 make use of the bb->aux pointers. It returns a set of trees | |
| 1140 (the INDIRECT_REFs itself) which can't trap. */ | |
| 1141 static struct pointer_set_t * | |
| 1142 get_non_trapping (void) | |
| 1143 { | |
| 1144 struct pointer_set_t *nontrap; | |
| 1145 struct dom_walk_data walk_data; | |
| 1146 | |
| 1147 nontrap = pointer_set_create (); | |
| 1148 seen_ssa_names = htab_create (128, name_to_bb_hash, name_to_bb_eq, | |
| 1149 free); | |
| 1150 /* We're going to do a dominator walk, so ensure that we have | |
| 1151 dominance information. */ | |
| 1152 calculate_dominance_info (CDI_DOMINATORS); | |
| 1153 | |
| 1154 /* Setup callbacks for the generic dominator tree walker. */ | |
| 1155 nontrap_set = nontrap; | |
| 1156 walk_data.dom_direction = CDI_DOMINATORS; | |
| 1157 walk_data.initialize_block_local_data = NULL; | |
|
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1158 walk_data.before_dom_children = nt_init_block; |
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1159 walk_data.after_dom_children = nt_fini_block; |
| 0 | 1160 walk_data.global_data = NULL; |
| 1161 walk_data.block_local_data_size = 0; | |
| 1162 | |
| 1163 init_walk_dominator_tree (&walk_data); | |
| 1164 walk_dominator_tree (&walk_data, ENTRY_BLOCK_PTR); | |
| 1165 fini_walk_dominator_tree (&walk_data); | |
| 1166 htab_delete (seen_ssa_names); | |
| 1167 | |
| 1168 return nontrap; | |
| 1169 } | |
| 1170 | |
| 1171 /* Do the main work of conditional store replacement. We already know | |
| 1172 that the recognized pattern looks like so: | |
| 1173 | |
| 1174 split: | |
| 1175 if (cond) goto MIDDLE_BB; else goto JOIN_BB (edge E1) | |
| 1176 MIDDLE_BB: | |
| 1177 something | |
| 1178 fallthrough (edge E0) | |
| 1179 JOIN_BB: | |
| 1180 some more | |
| 1181 | |
| 1182 We check that MIDDLE_BB contains only one store, that that store | |
| 1183 doesn't trap (not via NOTRAP, but via checking if an access to the same | |
| 1184 memory location dominates us) and that the store has a "simple" RHS. */ | |
| 1185 | |
| 1186 static bool | |
| 1187 cond_store_replacement (basic_block middle_bb, basic_block join_bb, | |
| 1188 edge e0, edge e1, struct pointer_set_t *nontrap) | |
| 1189 { | |
| 1190 gimple assign = last_and_only_stmt (middle_bb); | |
| 1191 tree lhs, rhs, name; | |
| 1192 gimple newphi, new_stmt; | |
| 1193 gimple_stmt_iterator gsi; | |
|
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1194 source_location locus; |
| 0 | 1195 enum tree_code code; |
| 1196 | |
| 1197 /* Check if middle_bb contains of only one store. */ | |
| 1198 if (!assign | |
| 1199 || gimple_code (assign) != GIMPLE_ASSIGN) | |
| 1200 return false; | |
| 1201 | |
|
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1202 locus = gimple_location (assign); |
| 0 | 1203 lhs = gimple_assign_lhs (assign); |
| 1204 rhs = gimple_assign_rhs1 (assign); | |
| 1205 if (!INDIRECT_REF_P (lhs)) | |
| 1206 return false; | |
| 1207 | |
| 1208 /* RHS is either a single SSA_NAME or a constant. */ | |
| 1209 code = gimple_assign_rhs_code (assign); | |
| 1210 if (get_gimple_rhs_class (code) != GIMPLE_SINGLE_RHS | |
| 1211 || (code != SSA_NAME && !is_gimple_min_invariant (rhs))) | |
| 1212 return false; | |
| 1213 /* Prove that we can move the store down. We could also check | |
| 1214 TREE_THIS_NOTRAP here, but in that case we also could move stores, | |
| 1215 whose value is not available readily, which we want to avoid. */ | |
| 1216 if (!pointer_set_contains (nontrap, lhs)) | |
| 1217 return false; | |
| 1218 | |
| 1219 /* Now we've checked the constraints, so do the transformation: | |
| 1220 1) Remove the single store. */ | |
| 1221 mark_symbols_for_renaming (assign); | |
| 1222 gsi = gsi_for_stmt (assign); | |
| 1223 gsi_remove (&gsi, true); | |
| 1224 | |
| 1225 /* 2) Create a temporary where we can store the old content | |
| 1226 of the memory touched by the store, if we need to. */ | |
| 1227 if (!condstoretemp || TREE_TYPE (lhs) != TREE_TYPE (condstoretemp)) | |
| 1228 { | |
| 1229 condstoretemp = create_tmp_var (TREE_TYPE (lhs), "cstore"); | |
| 1230 get_var_ann (condstoretemp); | |
| 1231 if (TREE_CODE (TREE_TYPE (lhs)) == COMPLEX_TYPE | |
| 1232 || TREE_CODE (TREE_TYPE (lhs)) == VECTOR_TYPE) | |
| 1233 DECL_GIMPLE_REG_P (condstoretemp) = 1; | |
| 1234 } | |
| 1235 add_referenced_var (condstoretemp); | |
| 1236 | |
| 1237 /* 3) Insert a load from the memory of the store to the temporary | |
| 1238 on the edge which did not contain the store. */ | |
| 1239 lhs = unshare_expr (lhs); | |
| 1240 new_stmt = gimple_build_assign (condstoretemp, lhs); | |
| 1241 name = make_ssa_name (condstoretemp, new_stmt); | |
| 1242 gimple_assign_set_lhs (new_stmt, name); | |
|
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1243 gimple_set_location (new_stmt, locus); |
| 0 | 1244 mark_symbols_for_renaming (new_stmt); |
| 1245 gsi_insert_on_edge (e1, new_stmt); | |
| 1246 | |
| 1247 /* 4) Create a PHI node at the join block, with one argument | |
| 1248 holding the old RHS, and the other holding the temporary | |
| 1249 where we stored the old memory contents. */ | |
| 1250 newphi = create_phi_node (condstoretemp, join_bb); | |
|
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1251 add_phi_arg (newphi, rhs, e0, locus); |
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1252 add_phi_arg (newphi, name, e1, locus); |
| 0 | 1253 |
| 1254 lhs = unshare_expr (lhs); | |
| 1255 new_stmt = gimple_build_assign (lhs, PHI_RESULT (newphi)); | |
| 1256 mark_symbols_for_renaming (new_stmt); | |
| 1257 | |
| 1258 /* 5) Insert that PHI node. */ | |
| 1259 gsi = gsi_after_labels (join_bb); | |
| 1260 if (gsi_end_p (gsi)) | |
| 1261 { | |
| 1262 gsi = gsi_last_bb (join_bb); | |
| 1263 gsi_insert_after (&gsi, new_stmt, GSI_NEW_STMT); | |
| 1264 } | |
| 1265 else | |
| 1266 gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT); | |
| 1267 | |
| 1268 return true; | |
| 1269 } | |
| 1270 | |
| 1271 /* Always do these optimizations if we have SSA | |
| 1272 trees to work on. */ | |
| 1273 static bool | |
| 1274 gate_phiopt (void) | |
| 1275 { | |
| 1276 return 1; | |
| 1277 } | |
| 1278 | |
| 1279 struct gimple_opt_pass pass_phiopt = | |
| 1280 { | |
| 1281 { | |
| 1282 GIMPLE_PASS, | |
| 1283 "phiopt", /* name */ | |
| 1284 gate_phiopt, /* gate */ | |
| 1285 tree_ssa_phiopt, /* execute */ | |
| 1286 NULL, /* sub */ | |
| 1287 NULL, /* next */ | |
| 1288 0, /* static_pass_number */ | |
| 1289 TV_TREE_PHIOPT, /* tv_id */ | |
|
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1290 PROP_cfg | PROP_ssa, /* properties_required */ |
| 0 | 1291 0, /* properties_provided */ |
| 1292 0, /* properties_destroyed */ | |
| 1293 0, /* todo_flags_start */ | |
| 1294 TODO_dump_func | |
| 1295 | TODO_ggc_collect | |
| 1296 | TODO_verify_ssa | |
| 1297 | TODO_verify_flow | |
| 1298 | TODO_verify_stmts /* todo_flags_finish */ | |
| 1299 } | |
| 1300 }; | |
| 1301 | |
| 1302 static bool | |
| 1303 gate_cselim (void) | |
| 1304 { | |
| 1305 return flag_tree_cselim; | |
| 1306 } | |
| 1307 | |
| 1308 struct gimple_opt_pass pass_cselim = | |
| 1309 { | |
| 1310 { | |
| 1311 GIMPLE_PASS, | |
| 1312 "cselim", /* name */ | |
| 1313 gate_cselim, /* gate */ | |
| 1314 tree_ssa_cs_elim, /* execute */ | |
| 1315 NULL, /* sub */ | |
| 1316 NULL, /* next */ | |
| 1317 0, /* static_pass_number */ | |
| 1318 TV_TREE_PHIOPT, /* tv_id */ | |
|
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1319 PROP_cfg | PROP_ssa, /* properties_required */ |
| 0 | 1320 0, /* properties_provided */ |
| 1321 0, /* properties_destroyed */ | |
| 1322 0, /* todo_flags_start */ | |
| 1323 TODO_dump_func | |
| 1324 | TODO_ggc_collect | |
| 1325 | TODO_verify_ssa | |
| 1326 | TODO_verify_flow | |
| 1327 | TODO_verify_stmts /* todo_flags_finish */ | |
| 1328 } | |
| 1329 }; |