1 /* ET-trees data structure implementation. 2 Contributed by Pavel Nejedly 3 Copyright (C) 2002, 2003, 2004, 2005 Free Software Foundation, Inc. 4 5 This file is part of the libiberty library. 6 Libiberty is free software; you can redistribute it and/or 7 modify it under the terms of the GNU Library General Public 8 License as published by the Free Software Foundation; either 9 version 2 of the License, or (at your option) any later version. 10 11 Libiberty is distributed in the hope that it will be useful, 12 but WITHOUT ANY WARRANTY; without even the implied warranty of 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 14 Library General Public License for more details. 15 16 You should have received a copy of the GNU Library General Public 17 License along with libiberty; see the file COPYING.LIB. If 18 not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, 19 Boston, MA 02110-1301, USA. 20 21 The ET-forest structure is described in: 22 D. D. Sleator and R. E. Tarjan. A data structure for dynamic trees. 23 J. G'omput. System Sci., 26(3):362 381, 1983. 24 */ 25 26 #include "config.h" 27 #include "system.h" 28 #include "coretypes.h" 29 #include "tm.h" 30 #include "et-forest.h" 31 #include "alloc-pool.h" 32 33 /* We do not enable this with ENABLE_CHECKING, since it is awfully slow. */ 34 #undef DEBUG_ET 35 36 #ifdef DEBUG_ET 37 #include "basic-block.h" 38 #endif 39 40 /* The occurrence of a node in the et tree. */ 41 struct et_occ 42 { 43 struct et_node *of; /* The node. */ 44 45 struct et_occ *parent; /* Parent in the splay-tree. */ 46 struct et_occ *prev; /* Left son in the splay-tree. */ 47 struct et_occ *next; /* Right son in the splay-tree. */ 48 49 int depth; /* The depth of the node is the sum of depth 50 fields on the path to the root. */ 51 int min; /* The minimum value of the depth in the subtree 52 is obtained by adding sum of depth fields 53 on the path to the root. */ 54 struct et_occ *min_occ; /* The occurrence in the subtree with the minimal 55 depth. */ 56 }; 57 58 static alloc_pool et_nodes; 59 static alloc_pool et_occurrences; 60 61 /* Changes depth of OCC to D. */ 62 63 static inline void 64 set_depth (struct et_occ *occ, int d) 65 { 66 if (!occ) 67 return; 68 69 occ->min += d - occ->depth; 70 occ->depth = d; 71 } 72 73 /* Adds D to the depth of OCC. */ 74 75 static inline void 76 set_depth_add (struct et_occ *occ, int d) 77 { 78 if (!occ) 79 return; 80 81 occ->min += d; 82 occ->depth += d; 83 } 84 85 /* Sets prev field of OCC to P. */ 86 87 static inline void 88 set_prev (struct et_occ *occ, struct et_occ *t) 89 { 90 #ifdef DEBUG_ET 91 gcc_assert (occ != t); 92 #endif 93 94 occ->prev = t; 95 if (t) 96 t->parent = occ; 97 } 98 99 /* Sets next field of OCC to P. */ 100 101 static inline void 102 set_next (struct et_occ *occ, struct et_occ *t) 103 { 104 #ifdef DEBUG_ET 105 gcc_assert (occ != t); 106 #endif 107 108 occ->next = t; 109 if (t) 110 t->parent = occ; 111 } 112 113 /* Recompute minimum for occurrence OCC. */ 114 115 static inline void 116 et_recomp_min (struct et_occ *occ) 117 { 118 struct et_occ *mson = occ->prev; 119 120 if (!mson 121 || (occ->next 122 && mson->min > occ->next->min)) 123 mson = occ->next; 124 125 if (mson && mson->min < 0) 126 { 127 occ->min = mson->min + occ->depth; 128 occ->min_occ = mson->min_occ; 129 } 130 else 131 { 132 occ->min = occ->depth; 133 occ->min_occ = occ; 134 } 135 } 136 137 #ifdef DEBUG_ET 138 /* Checks whether neighborhood of OCC seems sane. */ 139 140 static void 141 et_check_occ_sanity (struct et_occ *occ) 142 { 143 if (!occ) 144 return; 145 146 gcc_assert (occ->parent != occ); 147 gcc_assert (occ->prev != occ); 148 gcc_assert (occ->next != occ); 149 gcc_assert (!occ->next || occ->next != occ->prev); 150 151 if (occ->next) 152 { 153 gcc_assert (occ->next != occ->parent); 154 gcc_assert (occ->next->parent == occ); 155 } 156 157 if (occ->prev) 158 { 159 gcc_assert (occ->prev != occ->parent); 160 gcc_assert (occ->prev->parent == occ); 161 } 162 163 gcc_assert (!occ->parent 164 || occ->parent->prev == occ 165 || occ->parent->next == occ); 166 } 167 168 /* Checks whether tree rooted at OCC is sane. */ 169 170 static void 171 et_check_sanity (struct et_occ *occ) 172 { 173 et_check_occ_sanity (occ); 174 if (occ->prev) 175 et_check_sanity (occ->prev); 176 if (occ->next) 177 et_check_sanity (occ->next); 178 } 179 180 /* Checks whether tree containing OCC is sane. */ 181 182 static void 183 et_check_tree_sanity (struct et_occ *occ) 184 { 185 while (occ->parent) 186 occ = occ->parent; 187 188 et_check_sanity (occ); 189 } 190 191 /* For recording the paths. */ 192 193 /* An ad-hoc constant; if the function has more blocks, this won't work, 194 but since it is used for debugging only, it does not matter. */ 195 #define MAX_NODES 100000 196 197 static int len; 198 static void *datas[MAX_NODES]; 199 static int depths[MAX_NODES]; 200 201 /* Records the path represented by OCC, with depth incremented by DEPTH. */ 202 203 static int 204 record_path_before_1 (struct et_occ *occ, int depth) 205 { 206 int mn, m; 207 208 depth += occ->depth; 209 mn = depth; 210 211 if (occ->prev) 212 { 213 m = record_path_before_1 (occ->prev, depth); 214 if (m < mn) 215 mn = m; 216 } 217 218 fprintf (stderr, "%d (%d); ", ((basic_block) occ->of->data)->index, depth); 219 220 gcc_assert (len < MAX_NODES); 221 222 depths[len] = depth; 223 datas[len] = occ->of; 224 len++; 225 226 if (occ->next) 227 { 228 m = record_path_before_1 (occ->next, depth); 229 if (m < mn) 230 mn = m; 231 } 232 233 gcc_assert (mn == occ->min + depth - occ->depth); 234 235 return mn; 236 } 237 238 /* Records the path represented by a tree containing OCC. */ 239 240 static void 241 record_path_before (struct et_occ *occ) 242 { 243 while (occ->parent) 244 occ = occ->parent; 245 246 len = 0; 247 record_path_before_1 (occ, 0); 248 fprintf (stderr, "\n"); 249 } 250 251 /* Checks whether the path represented by OCC, with depth incremented by DEPTH, 252 was not changed since the last recording. */ 253 254 static int 255 check_path_after_1 (struct et_occ *occ, int depth) 256 { 257 int mn, m; 258 259 depth += occ->depth; 260 mn = depth; 261 262 if (occ->next) 263 { 264 m = check_path_after_1 (occ->next, depth); 265 if (m < mn) 266 mn = m; 267 } 268 269 len--; 270 gcc_assert (depths[len] == depth && datas[len] == occ->of); 271 272 if (occ->prev) 273 { 274 m = check_path_after_1 (occ->prev, depth); 275 if (m < mn) 276 mn = m; 277 } 278 279 gcc_assert (mn == occ->min + depth - occ->depth); 280 281 return mn; 282 } 283 284 /* Checks whether the path represented by a tree containing OCC was 285 not changed since the last recording. */ 286 287 static void 288 check_path_after (struct et_occ *occ) 289 { 290 while (occ->parent) 291 occ = occ->parent; 292 293 check_path_after_1 (occ, 0); 294 gcc_assert (!len); 295 } 296 297 #endif 298 299 /* Splay the occurrence OCC to the root of the tree. */ 300 301 static void 302 et_splay (struct et_occ *occ) 303 { 304 struct et_occ *f, *gf, *ggf; 305 int occ_depth, f_depth, gf_depth; 306 307 #ifdef DEBUG_ET 308 record_path_before (occ); 309 et_check_tree_sanity (occ); 310 #endif 311 312 while (occ->parent) 313 { 314 occ_depth = occ->depth; 315 316 f = occ->parent; 317 f_depth = f->depth; 318 319 gf = f->parent; 320 321 if (!gf) 322 { 323 set_depth_add (occ, f_depth); 324 occ->min_occ = f->min_occ; 325 occ->min = f->min; 326 327 if (f->prev == occ) 328 { 329 /* zig */ 330 set_prev (f, occ->next); 331 set_next (occ, f); 332 set_depth_add (f->prev, occ_depth); 333 } 334 else 335 { 336 /* zag */ 337 set_next (f, occ->prev); 338 set_prev (occ, f); 339 set_depth_add (f->next, occ_depth); 340 } 341 set_depth (f, -occ_depth); 342 occ->parent = NULL; 343 344 et_recomp_min (f); 345 #ifdef DEBUG_ET 346 et_check_tree_sanity (occ); 347 check_path_after (occ); 348 #endif 349 return; 350 } 351 352 gf_depth = gf->depth; 353 354 set_depth_add (occ, f_depth + gf_depth); 355 occ->min_occ = gf->min_occ; 356 occ->min = gf->min; 357 358 ggf = gf->parent; 359 360 if (gf->prev == f) 361 { 362 if (f->prev == occ) 363 { 364 /* zig zig */ 365 set_prev (gf, f->next); 366 set_prev (f, occ->next); 367 set_next (occ, f); 368 set_next (f, gf); 369 370 set_depth (f, -occ_depth); 371 set_depth_add (f->prev, occ_depth); 372 set_depth (gf, -f_depth); 373 set_depth_add (gf->prev, f_depth); 374 } 375 else 376 { 377 /* zag zig */ 378 set_prev (gf, occ->next); 379 set_next (f, occ->prev); 380 set_prev (occ, f); 381 set_next (occ, gf); 382 383 set_depth (f, -occ_depth); 384 set_depth_add (f->next, occ_depth); 385 set_depth (gf, -occ_depth - f_depth); 386 set_depth_add (gf->prev, occ_depth + f_depth); 387 } 388 } 389 else 390 { 391 if (f->prev == occ) 392 { 393 /* zig zag */ 394 set_next (gf, occ->prev); 395 set_prev (f, occ->next); 396 set_prev (occ, gf); 397 set_next (occ, f); 398 399 set_depth (f, -occ_depth); 400 set_depth_add (f->prev, occ_depth); 401 set_depth (gf, -occ_depth - f_depth); 402 set_depth_add (gf->next, occ_depth + f_depth); 403 } 404 else 405 { 406 /* zag zag */ 407 set_next (gf, f->prev); 408 set_next (f, occ->prev); 409 set_prev (occ, f); 410 set_prev (f, gf); 411 412 set_depth (f, -occ_depth); 413 set_depth_add (f->next, occ_depth); 414 set_depth (gf, -f_depth); 415 set_depth_add (gf->next, f_depth); 416 } 417 } 418 419 occ->parent = ggf; 420 if (ggf) 421 { 422 if (ggf->prev == gf) 423 ggf->prev = occ; 424 else 425 ggf->next = occ; 426 } 427 428 et_recomp_min (gf); 429 et_recomp_min (f); 430 #ifdef DEBUG_ET 431 et_check_tree_sanity (occ); 432 #endif 433 } 434 435 #ifdef DEBUG_ET 436 et_check_sanity (occ); 437 check_path_after (occ); 438 #endif 439 } 440 441 /* Create a new et tree occurrence of NODE. */ 442 443 static struct et_occ * 444 et_new_occ (struct et_node *node) 445 { 446 struct et_occ *nw; 447 448 if (!et_occurrences) 449 et_occurrences = create_alloc_pool ("et_occ pool", sizeof (struct et_occ), 300); 450 nw = pool_alloc (et_occurrences); 451 452 nw->of = node; 453 nw->parent = NULL; 454 nw->prev = NULL; 455 nw->next = NULL; 456 457 nw->depth = 0; 458 nw->min_occ = nw; 459 nw->min = 0; 460 461 return nw; 462 } 463 464 /* Create a new et tree containing DATA. */ 465 466 struct et_node * 467 et_new_tree (void *data) 468 { 469 struct et_node *nw; 470 471 if (!et_nodes) 472 et_nodes = create_alloc_pool ("et_node pool", sizeof (struct et_node), 300); 473 nw = pool_alloc (et_nodes); 474 475 nw->data = data; 476 nw->father = NULL; 477 nw->left = NULL; 478 nw->right = NULL; 479 nw->son = NULL; 480 481 nw->rightmost_occ = et_new_occ (nw); 482 nw->parent_occ = NULL; 483 484 return nw; 485 } 486 487 /* Releases et tree T. */ 488 489 void 490 et_free_tree (struct et_node *t) 491 { 492 while (t->son) 493 et_split (t->son); 494 495 if (t->father) 496 et_split (t); 497 498 pool_free (et_occurrences, t->rightmost_occ); 499 pool_free (et_nodes, t); 500 } 501 502 /* Releases et tree T without maintaining other nodes. */ 503 504 void 505 et_free_tree_force (struct et_node *t) 506 { 507 pool_free (et_occurrences, t->rightmost_occ); 508 if (t->parent_occ) 509 pool_free (et_occurrences, t->parent_occ); 510 pool_free (et_nodes, t); 511 } 512 513 /* Release the alloc pools, if they are empty. */ 514 515 void 516 et_free_pools (void) 517 { 518 free_alloc_pool_if_empty (&et_occurrences); 519 free_alloc_pool_if_empty (&et_nodes); 520 } 521 522 /* Sets father of et tree T to FATHER. */ 523 524 void 525 et_set_father (struct et_node *t, struct et_node *father) 526 { 527 struct et_node *left, *right; 528 struct et_occ *rmost, *left_part, *new_f_occ, *p; 529 530 /* Update the path represented in the splay tree. */ 531 new_f_occ = et_new_occ (father); 532 533 rmost = father->rightmost_occ; 534 et_splay (rmost); 535 536 left_part = rmost->prev; 537 538 p = t->rightmost_occ; 539 et_splay (p); 540 541 set_prev (new_f_occ, left_part); 542 set_next (new_f_occ, p); 543 544 p->depth++; 545 p->min++; 546 et_recomp_min (new_f_occ); 547 548 set_prev (rmost, new_f_occ); 549 550 if (new_f_occ->min + rmost->depth < rmost->min) 551 { 552 rmost->min = new_f_occ->min + rmost->depth; 553 rmost->min_occ = new_f_occ->min_occ; 554 } 555 556 t->parent_occ = new_f_occ; 557 558 /* Update the tree. */ 559 t->father = father; 560 right = father->son; 561 if (right) 562 left = right->left; 563 else 564 left = right = t; 565 566 left->right = t; 567 right->left = t; 568 t->left = left; 569 t->right = right; 570 571 father->son = t; 572 573 #ifdef DEBUG_ET 574 et_check_tree_sanity (rmost); 575 record_path_before (rmost); 576 #endif 577 } 578 579 /* Splits the edge from T to its father. */ 580 581 void 582 et_split (struct et_node *t) 583 { 584 struct et_node *father = t->father; 585 struct et_occ *r, *l, *rmost, *p_occ; 586 587 /* Update the path represented by the splay tree. */ 588 rmost = t->rightmost_occ; 589 et_splay (rmost); 590 591 for (r = rmost->next; r->prev; r = r->prev) 592 continue; 593 et_splay (r); 594 595 r->prev->parent = NULL; 596 p_occ = t->parent_occ; 597 et_splay (p_occ); 598 t->parent_occ = NULL; 599 600 l = p_occ->prev; 601 p_occ->next->parent = NULL; 602 603 set_prev (r, l); 604 605 et_recomp_min (r); 606 607 et_splay (rmost); 608 rmost->depth = 0; 609 rmost->min = 0; 610 611 pool_free (et_occurrences, p_occ); 612 613 /* Update the tree. */ 614 if (father->son == t) 615 father->son = t->right; 616 if (father->son == t) 617 father->son = NULL; 618 else 619 { 620 t->left->right = t->right; 621 t->right->left = t->left; 622 } 623 t->left = t->right = NULL; 624 t->father = NULL; 625 626 #ifdef DEBUG_ET 627 et_check_tree_sanity (rmost); 628 record_path_before (rmost); 629 630 et_check_tree_sanity (r); 631 record_path_before (r); 632 #endif 633 } 634 635 /* Finds the nearest common ancestor of the nodes N1 and N2. */ 636 637 struct et_node * 638 et_nca (struct et_node *n1, struct et_node *n2) 639 { 640 struct et_occ *o1 = n1->rightmost_occ, *o2 = n2->rightmost_occ, *om; 641 struct et_occ *l, *r, *ret; 642 int mn; 643 644 if (n1 == n2) 645 return n1; 646 647 et_splay (o1); 648 l = o1->prev; 649 r = o1->next; 650 if (l) 651 l->parent = NULL; 652 if (r) 653 r->parent = NULL; 654 et_splay (o2); 655 656 if (l == o2 || (l && l->parent != NULL)) 657 { 658 ret = o2->next; 659 660 set_prev (o1, o2); 661 if (r) 662 r->parent = o1; 663 } 664 else 665 { 666 ret = o2->prev; 667 668 set_next (o1, o2); 669 if (l) 670 l->parent = o1; 671 } 672 673 if (0 < o2->depth) 674 { 675 om = o1; 676 mn = o1->depth; 677 } 678 else 679 { 680 om = o2; 681 mn = o2->depth + o1->depth; 682 } 683 684 #ifdef DEBUG_ET 685 et_check_tree_sanity (o2); 686 #endif 687 688 if (ret && ret->min + o1->depth + o2->depth < mn) 689 return ret->min_occ->of; 690 else 691 return om->of; 692 } 693 694 /* Checks whether the node UP is an ancestor of the node DOWN. */ 695 696 bool 697 et_below (struct et_node *down, struct et_node *up) 698 { 699 struct et_occ *u = up->rightmost_occ, *d = down->rightmost_occ; 700 struct et_occ *l, *r; 701 702 if (up == down) 703 return true; 704 705 et_splay (u); 706 l = u->prev; 707 r = u->next; 708 709 if (!l) 710 return false; 711 712 l->parent = NULL; 713 714 if (r) 715 r->parent = NULL; 716 717 et_splay (d); 718 719 if (l == d || l->parent != NULL) 720 { 721 if (r) 722 r->parent = u; 723 set_prev (u, d); 724 #ifdef DEBUG_ET 725 et_check_tree_sanity (u); 726 #endif 727 } 728 else 729 { 730 l->parent = u; 731 732 /* In case O1 and O2 are in two different trees, we must just restore the 733 original state. */ 734 if (r && r->parent != NULL) 735 set_next (u, d); 736 else 737 set_next (u, r); 738 739 #ifdef DEBUG_ET 740 et_check_tree_sanity (u); 741 #endif 742 return false; 743 } 744 745 if (0 >= d->depth) 746 return false; 747 748 return !d->next || d->next->min + d->depth >= 0; 749 } 750