nsz Git - libfirm/blob - ir/be/bespillbelady3.c

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief       MIN-algorithm with some twists (aka belady spiller v3)
  23  * @author      Matthias Braun
  24  * @date        15.01.2008
  25  * @version     $Id$
  26  *
  27  * TODO:
  28  *   - handle phis correctly, decide whether we should spill them ~ok
  29  *   - merge multiple start worksets of blocks ~ok
  30  *   - how to and when to do the tentative phase...
  31  */
  32 #include "config.h"
  33
  34 #include <stdbool.h>
  35
  36 #include "debug.h"
  37 #include "list.h"
  38 #include "pdeq.h"
  39
  40 #include "irnode_t.h"
  41 #include "irprintf.h"
  42 #include "iredges_t.h"
  43 #include "irloop_t.h"
  44 #include "irgwalk.h"
  45 #include "execfreq.h"
  46
  47 #include "bemodule.h"
  48 #include "bespill.h"
  49 #include "beutil.h"
  50 #include "bespilloptions.h"
  51 #include "besched_t.h"
  52 #include "be_t.h"
  53
  54 #ifndef NDEBUG
  55 #define EXPENSIVE_CHECKS
  56 #endif
  57
  58 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  59
  60 typedef struct loop_edge_t loop_edge_t;
  61 struct loop_edge_t {
  62         ir_node     *block;
  63         int          pos;
  64         loop_edge_t *next;
  65 };
  66
  67 typedef struct loop_info_t loop_info_t;
  68 struct loop_info_t {
  69         ir_loop     *loop;
  70         loop_edge_t *entry_edges;
  71         loop_edge_t *exit_edges;
  72         size_t       max_register_pressure;
  73 };
  74
  75 typedef struct worklist_entry_t worklist_entry_t;
  76 struct worklist_entry_t {
  77         struct list_head  head;
  78         ir_node          *value;
  79         ir_node          *reload_point;
  80         ir_loop          *unused_livethrough_loop;
  81 };
  82
  83 #define foreach_worklist(entry, wl) list_for_each_entry(worklist_entry_t, entry, &(wl)->live_values, head)
  84
  85 typedef struct worklist_t worklist_t;
  86 struct worklist_t {
  87         struct list_head  live_values;
  88         size_t            n_live_values;
  89         ir_visited_t      visited;
  90 };
  91
  92 typedef struct block_info_t block_info_t;
  93 struct block_info_t {
  94         worklist_t *start_worklist;
  95         worklist_t *end_worklist;
  96 };
  97
  98 /** The register class we currently run on. */
  99 static const arch_register_class_t *cls;
 100 static struct obstack               obst;
 101 static spill_env_t                 *senv;
 102 static size_t                       n_regs;
 103 static size_t                       max_register_pressure;
 104 static bool                         tentative_mode;
 105 static bool                         should_have_reached_fixpoint;
 106 static bool                         do_push_unused_livethroughs;
 107 /** Execution frequency for the current graph. */
 108 static ir_exec_freq                *exec_freq;
 109 static ir_visited_t                 worklist_visited;
 110
 111 static worklist_t *new_worklist(void)
 112 {
 113         worklist_t *worklist = obstack_alloc(&obst, sizeof(worklist[0]));
 114         memset(worklist, 0, sizeof(worklist[0]));
 115
 116         INIT_LIST_HEAD(&worklist->live_values);
 117         worklist->n_live_values    = 0;
 118
 119         return worklist;
 120 }
 121
 122 static void mark_irn_not_visited(ir_node *node)
 123 {
 124         set_irn_visited(node, get_irg_visited(current_ir_graph) - 1);
 125 }
 126
 127 static bool worklist_contains(const ir_node *node)
 128 {
 129         return irn_visited(node);
 130 }
 131
 132 static block_info_t *get_block_info(ir_node *block)
 133 {
 134         block_info_t *info = get_irn_link(block);
 135         if (info != NULL)
 136                 return info;
 137
 138         info = obstack_alloc(&obst, sizeof(info[0]));
 139         memset(info, 0, sizeof(info[0]));
 140         set_irn_link(block, info);
 141         return info;
 142 }
 143
 144 static void deactivate_worklist(const worklist_t *worklist)
 145 {
 146         worklist_entry_t *entry;
 147
 148         foreach_worklist(entry, worklist) {
 149                 assert(worklist_contains(entry->value));
 150                 mark_irn_not_visited(entry->value);
 151                 set_irn_link(entry->value, NULL);
 152         }
 153 }
 154
 155 static void activate_worklist(const worklist_t *worklist)
 156 {
 157         worklist_entry_t *entry;
 158
 159         foreach_worklist(entry, worklist) {
 160                 assert(!worklist_contains(entry->value));
 161                 mark_irn_visited(entry->value);
 162                 set_irn_link(entry->value, entry);
 163         }
 164 }
 165
 166 /**
 167  * duplicate a worklist and directly activates it
 168  */
 169 static void fill_and_activate_worklist(worklist_t *new_worklist,
 170                 const worklist_t *worklist, ir_node *block, ir_node *succ_block,
 171                 int succ_pos)
 172 {
 173         ir_node          *reload_point  = NULL;
 174         size_t            n_live_values = 0;
 175         worklist_entry_t *entry;
 176
 177         if (succ_block != NULL &&
 178                         (get_Block_n_cfgpreds(succ_block) > 1
 179                          || get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) > 1)) {
 180                 reload_point = be_get_end_of_block_insertion_point(block);
 181         }
 182
 183         foreach_worklist(entry, worklist) {
 184                 ir_node          *value = entry->value;
 185                 worklist_entry_t *new_entry;
 186
 187                 if (new_worklist->n_live_values >= n_regs)
 188                         break;
 189
 190                 if (is_Phi(value) && get_nodes_block(value) == succ_block) {
 191                         value = get_Phi_pred(value, succ_pos);
 192
 193                         /* can happen for unknown phi preds */
 194                         if (!arch_irn_consider_in_reg_alloc(cls, value))
 195                                 continue;
 196                 }
 197
 198                 if (irn_visited_else_mark(value))
 199                         continue;
 200
 201                 new_entry = obstack_alloc(&obst, sizeof(new_entry[0]));
 202                 memset(new_entry, 0, sizeof(new_entry[0]));
 203
 204                 new_entry->value = value;
 205                 if (reload_point != NULL) {
 206                         new_entry->reload_point = reload_point;
 207                 } else {
 208                         new_entry->reload_point = entry->reload_point;
 209                 }
 210
 211                 list_add_tail(&new_entry->head, &new_worklist->live_values);
 212                 ++n_live_values;
 213
 214                 set_irn_link(value, new_entry);
 215                 new_worklist->n_live_values++;
 216         }
 217 }
 218
 219 static worklist_t *duplicate_worklist(const worklist_t *worklist)
 220 {
 221         worklist_t       *new_worklist;
 222         struct list_head *entry;
 223
 224         new_worklist = obstack_alloc(&obst, sizeof(new_worklist[0]));
 225         memset(new_worklist, 0, sizeof(new_worklist[0]));
 226         INIT_LIST_HEAD(&new_worklist->live_values);
 227         new_worklist->n_live_values = worklist->n_live_values;
 228
 229         list_for_each(entry, &worklist->live_values) {
 230                 worklist_entry_t *wl_entry  = list_entry(entry, worklist_entry_t, head);
 231                 worklist_entry_t *new_entry
 232                         = obstack_alloc(&obst, sizeof(new_entry[0]));
 233
 234                 memcpy(new_entry, wl_entry, sizeof(new_entry[0]));
 235                 list_add_tail(&new_entry->head, &new_worklist->live_values);
 236         }
 237
 238         return new_worklist;
 239 }
 240
 241 #ifdef DEBUG_libfirm
 242 static void print_worklist(const worklist_t *worklist, int level)
 243 {
 244         struct list_head *entry;
 245
 246         DB((dbg, level, "%d values: ", worklist->n_live_values));
 247         list_for_each(entry, &worklist->live_values) {
 248                 worklist_entry_t *wl_entry
 249                         = list_entry(entry, worklist_entry_t, head);
 250
 251                 DB((dbg, level, "%+F ", wl_entry->value));
 252         }
 253 }
 254 #endif
 255
 256
 257 /**
 258  * Clear the link fields of a loop and all
 259  * its child loops.
 260  *
 261  * @param loop  the root loop
 262  */
 263 static void clear_loop_info(ir_loop *loop)
 264 {
 265         int n_elements = get_loop_n_elements(loop);
 266         int i;
 267
 268         loop->link = NULL;
 269         for (i = 0; i < n_elements; ++i) {
 270                 loop_element element = get_loop_element(loop, i);
 271                 if (*element.kind != k_ir_loop)
 272                         continue;
 273
 274                 clear_loop_info(element.son);
 275         }
 276 }
 277
 278 static loop_info_t *get_loop_info(ir_loop *loop)
 279 {
 280         loop_info_t *info = loop->link;
 281         if (info != NULL)
 282                 return info;
 283
 284         info = obstack_alloc(&obst, sizeof(info[0]));
 285         memset(info, 0, sizeof(info[0]));
 286         info->loop = loop;
 287         loop->link = info;
 288         return info;
 289 }
 290
 291 /**
 292  * constructs loop in+out edges when called in a block walker
 293  */
 294 static void construct_loop_edges(ir_node *block, void *data)
 295 {
 296         int      n_cfgpreds = get_Block_n_cfgpreds(block);
 297         ir_loop *loop       = get_irn_loop(block);
 298         int      i;
 299
 300         (void) data;
 301
 302         for (i = 0; i < n_cfgpreds; ++i) {
 303                 ir_node     *cfgpred_block = get_Block_cfgpred_block(block, i);
 304                 ir_loop     *cfgpred_loop  = get_irn_loop(cfgpred_block);
 305                 loop_edge_t *edge;
 306                 bool        is_exit_edge;
 307                 ir_loop     *l, *goal;
 308
 309                 if (cfgpred_loop == loop)
 310                         continue;
 311
 312                 /* critical edges are splitted, so we can't jump from 1 loop
 313                  * directly into another without going out of it */
 314                 assert(get_loop_depth(cfgpred_loop) != get_loop_depth(loop));
 315
 316                 /* edge out of loop */
 317                 if (get_loop_depth(cfgpred_loop) > get_loop_depth(loop)) {
 318                         is_exit_edge = true;
 319                         l            = cfgpred_loop;
 320                         goal         = loop;
 321                 } else {
 322                         is_exit_edge = false;
 323                         l            = loop;
 324                         goal         = cfgpred_loop;
 325                 }
 326
 327                 /* this might be a jump out/in multiple loops */
 328                 do {
 329                         loop_info_t *l_info = get_loop_info(l);
 330
 331                         edge = obstack_alloc(&obst, sizeof(edge[0]));
 332                         memset(edge, 0, sizeof(edge[0]));
 333                         edge->block = block;
 334                         edge->pos   = i;
 335
 336                         if (is_exit_edge) {
 337                                 edge->next         = l_info->exit_edges;
 338                                 l_info->exit_edges = edge;
 339                                 assert(get_loop_depth(loop) < get_loop_depth(l));
 340                         } else {
 341                                 edge->next          = l_info->entry_edges;
 342                                 l_info->entry_edges = edge;
 343                                 assert(get_loop_depth(cfgpred_loop) < get_loop_depth(l));
 344                         }
 345                         l = get_loop_outer_loop(l);
 346                 } while (l != goal);
 347         }
 348 }
 349
 350
 351
 352
 353 static void place_reload(worklist_entry_t *entry)
 354 {
 355         if (tentative_mode)
 356                 return;
 357
 358         DB((dbg, LEVEL_1, "reload of %+F before %+F\n", entry->value,
 359                 entry->reload_point));
 360         assert(entry->reload_point != NULL);
 361         be_add_reload(senv, entry->value, entry->reload_point, cls, 1);
 362         entry->reload_point = NULL;
 363 }
 364
 365 /**
 366  * makes sure the worklist contains not more than n_regs - room_needed entries
 367  */
 368 static void make_room(worklist_t *worklist, size_t room_needed)
 369 {
 370         int               i;
 371         int               spills_needed;
 372         struct list_head *entry;
 373
 374         spills_needed = worklist->n_live_values + room_needed - n_regs;
 375         if (spills_needed <= 0)
 376                 return;
 377
 378         entry = worklist->live_values.next;
 379         for(i = spills_needed; i > 0; --i) {
 380                 struct list_head *next = entry->next;
 381                 worklist_entry_t *wl_entry
 382                         = list_entry(entry, worklist_entry_t, head);
 383
 384                 assert(worklist_contains(wl_entry->value));
 385                 mark_irn_not_visited(wl_entry->value);
 386                 place_reload(wl_entry);
 387                 list_del(entry);
 388
 389                 entry = next;
 390         }
 391         worklist->n_live_values -= spills_needed;
 392 }
 393
 394 /**
 395  * a value was used, so bring it to the back of the worklist (which might
 396  * result in a spill of another value).
 397  */
 398 static void val_used(worklist_t *worklist, ir_node *value, ir_node *sched_point)
 399 {
 400         /* already in the worklist? move around, otherwise add at back */
 401         worklist_entry_t *entry = get_irn_link(value);
 402
 403         assert(arch_irn_consider_in_reg_alloc(cls, value));
 404
 405         if (worklist_contains(value)) {
 406                 assert(entry != NULL);
 407
 408                 list_del(&entry->head);
 409         } else {
 410                 if (entry == NULL) {
 411                         entry        = obstack_alloc(&obst, sizeof(entry[0]));
 412                         memset(entry, 0, sizeof(entry[0]));
 413
 414                         entry->value = value;
 415                         set_irn_link(value, entry);
 416                 }
 417
 418                 ++worklist->n_live_values;
 419                 mark_irn_visited(value);
 420         }
 421
 422         entry->reload_point = sched_point;
 423         list_add_tail(&entry->head, &worklist->live_values);
 424 }
 425
 426 static void worklist_remove(worklist_t *worklist, ir_node *value)
 427 {
 428         worklist_entry_t *entry = get_irn_link(value);
 429         assert(entry != NULL);
 430         list_del(&entry->head);
 431         --worklist->n_live_values;
 432
 433         assert(worklist_contains(value));
 434         mark_irn_not_visited(value);
 435 }
 436
 437 static void update_max_pressure(worklist_t *worklist)
 438 {
 439         if (worklist->n_live_values > max_register_pressure)
 440                 max_register_pressure = worklist->n_live_values;
 441 }
 442
 443 static void do_spilling(ir_node *block, worklist_t *worklist)
 444 {
 445         ir_node *node;
 446
 447         assert(worklist != NULL);
 448
 449         sched_foreach_reverse(block, node) {
 450                 int    i, arity;
 451                 size_t n_defs = 0;
 452
 453                 DB((dbg, LEVEL_2, "\t%+F... ", node));
 454                 update_max_pressure(worklist);
 455
 456                 if (is_Phi(node)) {
 457                         ir_node *node2;
 458                         /* TODO: if we have some free registers, then we could decide to
 459                          * not spill some phis (but not for phis where at least 1 input is
 460                          * themselfes) */
 461
 462                         /* we have to spill all phis that are not live */
 463                         sched_foreach_reverse_from(node, node2) {
 464                                 assert(is_Phi(node2));
 465
 466                                 if (worklist_contains(node2))
 467                                         continue;
 468                                 if (!arch_irn_consider_in_reg_alloc(cls, node2))
 469                                         continue;
 470
 471                                 if (!tentative_mode)
 472                                         be_spill_phi(senv, node2);
 473                         }
 474                         DB((dbg, LEVEL_2, "\n"));
 475                         break;
 476                 }
 477
 478                 /* remove values defined by this instruction from the workset. Values
 479                  * defined but not in the workset need free registers */
 480                 if (get_irn_mode(node) == mode_T) {
 481                         const ir_edge_t *edge;
 482
 483                         foreach_out_edge(node, edge) {
 484                                 ir_node *proj = get_edge_src_irn(edge);
 485                                 if (!arch_irn_consider_in_reg_alloc(cls, proj))
 486                                         continue;
 487                                 if (worklist_contains(proj)) {
 488                                         worklist_remove(worklist, proj);
 489                                 } else {
 490                                         ++n_defs;
 491                                 }
 492                         }
 493                 } else if (arch_irn_consider_in_reg_alloc(cls, node)) {
 494                         if (worklist_contains(node)) {
 495                                 worklist_remove(worklist, node);
 496                         } else {
 497                                 n_defs = 1;
 498                         }
 499                 }
 500
 501                 /* make sure we have enough free registers for the spills */
 502                 make_room(worklist, n_defs);
 503
 504                 /* put all values used by the instruction into the workset */
 505                 arity = get_irn_arity(node);
 506                 for(i = 0; i < arity; ++i) {
 507                         ir_node *use = get_irn_n(node, i);
 508
 509                         if (!arch_irn_consider_in_reg_alloc(cls, use))
 510                                 continue;
 511
 512                         val_used(worklist, use, node);
 513                 }
 514
 515                 /* we might have too many values in the worklist now and need to spill
 516                  * some */
 517                 make_room(worklist, 0);
 518
 519 #ifdef DEBUG_libfirm
 520                 print_worklist(worklist, LEVEL_2);
 521                 DB((dbg, LEVEL_2, "\n"));
 522 #endif
 523         }
 524
 525         update_max_pressure(worklist);
 526
 527 #ifdef DEBUG_libfirm
 528         DB((dbg, LEVEL_1, "worklist at begin of %+F:", block));
 529         print_worklist(worklist, LEVEL_1);
 530         DB((dbg, LEVEL_1, "\n"));
 531 #endif
 532 }
 533
 534 static bool worklists_equal(const worklist_t *wl1, const worklist_t *wl2)
 535 {
 536         const struct list_head *i1 = &wl1->live_values;
 537         const struct list_head *i2 = &wl2->live_values;
 538
 539         for ( ; i1 != &wl1->live_values && i2 != &wl2->live_values;
 540                         i1 = i1->next, i2 = i2->next) {
 541                 worklist_entry_t *entry1 = list_entry(i1, worklist_entry_t, head);
 542                 worklist_entry_t *entry2 = list_entry(i2, worklist_entry_t, head);
 543
 544                 if (entry1->value != entry2->value)
 545                         return false;
 546         }
 547         /* both lists at the end */
 548         if (i1 != &wl1->live_values || i2 != &wl2->live_values)
 549                 return false;
 550
 551         return true;
 552 }
 553
 554 static bool fill_start_worklist(worklist_t *new_worklist, ir_node *block)
 555 {
 556         double           best_execfreq   = -1;
 557         worklist_t      *best_worklist   = NULL;
 558         ir_node         *best_succ_block = NULL;
 559         int              best_pos;
 560         const ir_edge_t *edge;
 561
 562         /* construct worklist */
 563         foreach_block_succ(block, edge) {
 564                 ir_node      *succ_block = get_edge_src_irn(edge);
 565                 double       execfreq    = get_block_execfreq(exec_freq, succ_block);
 566                 block_info_t *block_info;
 567                 worklist_t   *succ_worklist;
 568
 569                 if (execfreq < best_execfreq)
 570                         continue;
 571
 572                 block_info    = get_block_info(succ_block);
 573                 succ_worklist = block_info->start_worklist;
 574
 575                 if (succ_worklist == NULL || succ_worklist->visited >= worklist_visited)
 576                         continue;
 577
 578                 best_execfreq   = execfreq;
 579                 best_worklist   = succ_worklist;
 580                 best_succ_block = succ_block;
 581                 best_pos        = get_edge_src_pos(edge);
 582         }
 583
 584         if (best_worklist == NULL)
 585                 return false;
 586         best_worklist->visited = worklist_visited;
 587
 588         fill_and_activate_worklist(new_worklist, best_worklist, block,
 589                         best_succ_block, best_pos);
 590         return true;
 591 }
 592
 593 static worklist_t *construct_start_worklist(ir_node *block)
 594 {
 595         worklist_t *worklist = new_worklist();
 596
 597         ++worklist_visited;
 598
 599         while(fill_start_worklist(worklist, block)) {
 600                 if (worklist->n_live_values >= n_regs)
 601                         break;
 602         }
 603
 604         return worklist;
 605 }
 606
 607 static void process_block(ir_node *block, void *env)
 608 {
 609         block_info_t    *block_info;
 610         worklist_t      *worklist;
 611         int              n_preds;
 612
 613         (void) env;
 614         DB((dbg, LEVEL_1, "Processing %+F\n", block));
 615
 616         worklist   = construct_start_worklist(block);
 617         block_info = get_block_info(block);
 618
 619 #ifdef DEBUG_libfirm
 620         DB((dbg, LEVEL_1, "worklist at end of %+F:", block));
 621         print_worklist(worklist, LEVEL_1);
 622         DB((dbg, LEVEL_1, "\n"));
 623
 624         if (should_have_reached_fixpoint) {
 625                 assert(worklists_equal(block_info->end_worklist, worklist));
 626         }
 627 #endif
 628         block_info->end_worklist = duplicate_worklist(worklist);
 629
 630         do_spilling(block, worklist);
 631         deactivate_worklist(worklist);
 632
 633 #ifdef DEBUG_libfirm
 634         if (should_have_reached_fixpoint) {
 635                 assert(worklists_equal(block_info->start_worklist, worklist));
 636         }
 637 #endif
 638         block_info->start_worklist = worklist;
 639
 640         /* we shouldn't have any live values left at the start block */
 641         n_preds = get_Block_n_cfgpreds(block);
 642         //assert(n_preds != 0 || worklist->n_live_values == 0);
 643 }
 644
 645 typedef union block_or_loop_t block_or_loop_t;
 646 union block_or_loop_t {
 647         ir_node *block;
 648         ir_loop *loop;
 649 };
 650
 651 static block_or_loop_t *loop_blocks;
 652 static ir_loop         *current_loop;
 653
 654 static void find_blocks(ir_node *block);
 655
 656 static void find_in_loop(ir_loop *loop, ir_node *entry)
 657 {
 658         loop_info_t     *loop_info = get_loop_info(loop);
 659         block_or_loop_t block_or_loop;
 660         loop_edge_t     *edge;
 661
 662         /* simply mark 1 block in the loop to indicate that the loop was already
 663          * processed */
 664         ir_node *some_block = loop_info->entry_edges->block;
 665         if (Block_block_visited(some_block))
 666                 return;
 667
 668         block_or_loop.loop = loop;
 669         ARR_APP1(block_or_loop_t, loop_blocks, block_or_loop);
 670
 671 #ifndef NDEBUG
 672         {
 673                 /* we should be 1 of the entry blocks */
 674                 loop_edge_t *edge  = loop_info->entry_edges;
 675                 bool         found = false;
 676                 for ( ; edge != NULL; edge = edge->next) {
 677                         if (edge->block == entry) {
 678                                 found = true;
 679                                 break;
 680                         }
 681                 }
 682                 assert(found);
 683         }
 684 #else
 685         (void) entry;
 686 #endif
 687
 688         /* check all loop successors */
 689         for (edge = loop_info->exit_edges; edge != NULL; edge = edge->next) {
 690                 ir_node *succ      = edge->block;
 691                 ir_loop *succ_loop = get_irn_loop(succ);
 692
 693                 if (succ_loop == current_loop) {
 694                         find_blocks(succ);
 695                 } else {
 696                         assert(get_loop_depth(succ_loop) < get_loop_depth(current_loop));
 697                 }
 698         }
 699 }
 700
 701 static void find_blocks(ir_node *block)
 702 {
 703         const ir_edge_t *edge;
 704         block_or_loop_t block_or_loop;
 705
 706         if (Block_block_visited(block))
 707                 return;
 708
 709         block_or_loop.block = block;
 710
 711         ARR_APP1(block_or_loop_t, loop_blocks, block_or_loop);
 712         mark_Block_block_visited(block);
 713
 714         foreach_block_succ(block, edge) {
 715                 ir_node *succ = get_edge_src_irn(edge);
 716
 717                 /* is it part of the current loop? */
 718                 ir_loop *loop = get_irn_loop(succ);
 719                 if (loop != current_loop) {
 720                         /* a sub-loop? */
 721                         if (get_loop_depth(loop) > get_loop_depth(current_loop)) {
 722                                 find_in_loop(loop, succ);
 723                         } else {
 724                                 /* parent loop: we're not interested in the block */
 725                         }
 726                 } else {
 727                         find_blocks(succ);
 728                 }
 729         }
 730 }
 731
 732 /**
 733  * append an entry to a worklist. WARNING: The entry must not already be in the
 734  * worklist.
 735  */
 736 static void worklist_append(worklist_t *worklist, ir_node *value,
 737                             ir_node *reload_point,
 738                                                         ir_loop *unused_livethrough_loop)
 739 {
 740         worklist_entry_t *entry;
 741
 742 #ifdef EXPENSIVE_CHECKS
 743         foreach_worklist(entry, worklist) {
 744                 assert(entry->value != value);
 745         }
 746 #endif
 747
 748         entry = obstack_alloc(&obst, sizeof(*entry));
 749         memset(entry, 0, sizeof(entry[0]));
 750
 751         entry->value                   = value;
 752         entry->reload_point            = reload_point;
 753         entry->unused_livethrough_loop = unused_livethrough_loop;
 754         list_add_tail(&entry->head, &worklist->live_values);
 755         ++worklist->n_live_values;
 756         assert(worklist->n_live_values <= n_regs);
 757 }
 758
 759 static void push_unused_livethrough(loop_info_t *loop_info, ir_node *value)
 760 {
 761         loop_edge_t *edge;
 762         ++worklist_visited;
 763
 764         /* add the value to all loop exit and entry blocks */
 765         for (edge = loop_info->exit_edges; edge != NULL; edge = edge->next) {
 766                 ir_node            *block
 767                         = get_Block_cfgpred_block(edge->block, edge->pos);
 768                 const block_info_t *info     = get_block_info(block);
 769                 worklist_t         *worklist = info->end_worklist;
 770                 ir_node            *reload_point = NULL;
 771
 772                 if (worklist->visited >= worklist_visited)
 773                         continue;
 774                 worklist->visited = worklist_visited;
 775
 776                 /* TODO: we need a smarter mechanism here, that makes the reloader place
 777                  * reload nodes on all loop exits... */
 778
 779                 worklist_append(worklist, value, reload_point, loop_info->loop);
 780         }
 781         edge = loop_info->entry_edges;
 782         for ( ; edge != NULL; edge = edge->next) {
 783                 ir_node            *entry_block = edge->block;
 784                 const block_info_t *info        = get_block_info(entry_block);
 785                 worklist_t         *worklist    = info->start_worklist;
 786                 ir_node            *pred_block;
 787                 ir_node            *reload_point;
 788
 789                 if (worklist->visited >= worklist_visited)
 790                         continue;
 791                 worklist->visited = worklist_visited;
 792
 793                 pred_block   = get_Block_cfgpred_block(entry_block, edge->pos);
 794                 reload_point = be_get_end_of_block_insertion_point(pred_block);
 795
 796                 worklist_append(worklist, value, reload_point, loop_info->loop);
 797         }
 798
 799         set_irn_link(value, NULL);
 800         ++loop_info->max_register_pressure;
 801 }
 802
 803 static void push_unused_livethroughs(loop_info_t *loop_info)
 804 {
 805         loop_edge_t *edge;
 806
 807         /* we can only push unused livethroughs if register pressure inside the loop
 808          * was low enough */
 809         if (loop_info->max_register_pressure >= n_regs)
 810                 return;
 811
 812         /* find unused livethroughs: register pressure in the loop was low enough
 813          * which means that we had no spills which implies that at every point in
 814          * the loop all*/
 815         for (edge = loop_info->exit_edges; edge != NULL; edge = edge->next) {
 816                 ir_node            *block          = edge->block;
 817                 const block_info_t *info           = get_block_info(block);
 818                 worklist_t         *start_worklist = info->start_worklist;
 819                 ir_node            *exit_block;
 820                 const block_info_t *exit_info;
 821                 worklist_t         *end_worklist;
 822                 struct list_head   *entry;
 823
 824                 if (start_worklist == NULL)
 825                         continue;
 826
 827                 exit_block   = get_Block_cfgpred_block(edge->block, edge->pos);
 828                 exit_info    = get_block_info(exit_block);
 829                 end_worklist = exit_info->end_worklist;
 830
 831                 activate_worklist(end_worklist);
 832                 /* all values contained in the start_worklist, which are not available
 833                  * in the end_worklist, must be unused livethroughs */
 834
 835                 list_for_each(entry, &start_worklist->live_values) {
 836                         worklist_entry_t *wl_entry
 837                                 = list_entry(entry, worklist_entry_t, head);
 838                         ir_node *value = wl_entry->value;
 839
 840                         if (loop_info->max_register_pressure >= n_regs)
 841                                 break;
 842
 843
 844                         if (!worklist_contains(value)) {
 845                                 /* add it to all loop exits */
 846                                 DB((dbg, LEVEL_2, "Found unused livethrough: %+F (regpressure in loop %d)\n", value, loop_info->max_register_pressure));
 847                                 push_unused_livethrough(loop_info, value);
 848                                 /* the value should now be part of end_worklist, so mark it */
 849                                 mark_irn_visited(value);
 850                         }
 851                 }
 852
 853                 deactivate_worklist(end_worklist);
 854         }
 855 }
 856
 857 static void process_block_or_loop(const block_or_loop_t block_or_loop)
 858 {
 859         if (block_or_loop.loop->kind == k_ir_loop) {
 860                 loop_info_t *loop_info = get_loop_info(block_or_loop.loop);
 861
 862                 if (do_push_unused_livethroughs)
 863                         push_unused_livethroughs(loop_info);
 864
 865                 if (loop_info->max_register_pressure > max_register_pressure)
 866                         max_register_pressure = loop_info->max_register_pressure;
 867
 868                 return;
 869         }
 870         process_block(block_or_loop.block, NULL);
 871 }
 872
 873 static void process_loop(ir_loop *loop)
 874 {
 875         int         n_elements = get_loop_n_elements(loop);
 876         int         i, len;
 877         loop_info_t *loop_info;
 878         loop_edge_t *edge;
 879         ir_node     *some_block;
 880
 881         /* first handle all sub-loops */
 882         for (i = 0; i < n_elements; ++i) {
 883                 loop_element element = get_loop_element(loop, i);
 884                 if (*element.kind != k_ir_loop)
 885                         continue;
 886
 887                 process_loop(element.son);
 888         }
 889
 890         /* create a postorder of the blocks */
 891         loop_info = get_loop_info(loop);
 892         edge      = loop_info->entry_edges;
 893         if (edge != NULL) {
 894                 some_block = edge->block;
 895         } else {
 896                 assert(loop == get_irg_loop(current_ir_graph));
 897                 some_block = get_irg_start_block(current_ir_graph);
 898         }
 899
 900         loop_blocks  = NEW_ARR_F(block_or_loop_t, 0);
 901         current_loop = loop;
 902
 903         ir_reserve_resources(current_ir_graph, IR_RESOURCE_BLOCK_VISITED);
 904         inc_irg_block_visited(current_ir_graph);
 905         find_blocks(some_block);
 906         /* for endless loops the end-block might be unreachable */
 907         if (loop == get_irg_loop(current_ir_graph)) {
 908                 find_blocks(get_irg_end_block(current_ir_graph));
 909         }
 910         ir_free_resources(current_ir_graph, IR_RESOURCE_BLOCK_VISITED);
 911
 912         DB((dbg, LEVEL_3, "Block List for loop %p\n", loop));
 913         len = ARR_LEN(loop_blocks);
 914         for (i = 0; i < len; ++i) {
 915                 block_or_loop_t block_or_loop = loop_blocks[i];
 916                 if (block_or_loop.loop->kind == k_ir_loop) {
 917                         DB((dbg, LEVEL_3, " L-%p", block_or_loop.loop));
 918                 } else {
 919                         DB((dbg, LEVEL_3, " B-%+F", block_or_loop.block));
 920                 }
 921         }
 922         DB((dbg, LEVEL_3, "\n"));
 923
 924         max_register_pressure = 0;
 925
 926         /* run1: tentative phase */
 927         tentative_mode = true;
 928         for (i = len-1; i >= 0; --i) {
 929                 process_block_or_loop(loop_blocks[i]);
 930         }
 931
 932         /* run2: tentative phase - should reach fixpoint */
 933         tentative_mode = true;
 934         for (i = len-1; i >= 0; --i) {
 935                 process_block_or_loop(loop_blocks[i]);
 936         }
 937
 938 #ifndef NDEBUG
 939         /* run3: tentative phase - check fixpoint */
 940         tentative_mode               = true;
 941         should_have_reached_fixpoint = true;
 942         for (i = len-1; i >= 0; --i) {
 943                 process_block_or_loop(loop_blocks[i]);
 944         }
 945         should_have_reached_fixpoint = false;
 946 #endif
 947
 948         /* run4: add spills/reloads */
 949         tentative_mode              = false;
 950         do_push_unused_livethroughs = true;
 951         for (i = len-1; i >= 0; --i) {
 952                 process_block_or_loop(loop_blocks[i]);
 953         }
 954         do_push_unused_livethroughs = false;
 955
 956         loop_info->max_register_pressure = max_register_pressure;
 957         DB((dbg, LEVEL_2, "Regpressure in loop %p: %u\n", loop,
 958                                 (unsigned) max_register_pressure));
 959
 960         DEL_ARR_F(loop_blocks);
 961 }
 962
 963 static void fix_block_borders(ir_node *block, void *data)
 964 {
 965         block_info_t *block_info     = get_block_info(block);
 966         worklist_t   *start_worklist = block_info->start_worklist;
 967         int           n_cfgpreds     = get_Block_n_cfgpreds(block);
 968         ir_loop      *loop           = get_irn_loop(block);
 969         int           i;
 970
 971         (void) data;
 972         assert(start_worklist != NULL);
 973
 974         for (i = 0; i < n_cfgpreds; ++i) {
 975                 ir_node      *pred_block      = get_Block_cfgpred_block(block, i);
 976                 block_info_t *pred_block_info = get_block_info(pred_block);
 977                 worklist_t   *end_worklist    = pred_block_info->end_worklist;
 978                 ir_loop      *pred_loop       = get_irn_loop(pred_block);
 979                 bool          is_loop_entry   = false;
 980                 worklist_entry_t *entry;
 981
 982                 assert(end_worklist != NULL);
 983
 984                 if (get_loop_depth(pred_loop) < get_loop_depth(loop)) {
 985                         is_loop_entry = true;
 986                 }
 987
 988                 /* reload missing values */
 989                 activate_worklist(end_worklist);
 990
 991                 foreach_worklist(entry, start_worklist) {
 992                         ir_node *value = entry->value;
 993
 994                         if (!is_loop_entry && entry->unused_livethrough_loop != NULL)
 995                                 continue;
 996
 997                         if (is_Phi(value) && get_nodes_block(value) == block) {
 998                                 value = get_irn_n(value, i);
 999
1000                                 /* we might have unknowns as argument for the phi */
1001                                 if (!arch_irn_consider_in_reg_alloc(cls, value))
1002                                         continue;
1003                         }
1004                         if (worklist_contains(value))
1005                                 continue;
1006                         be_add_reload_on_edge(senv, value, block, i, cls, 1);
1007                 }
1008
1009                 deactivate_worklist(end_worklist);
1010         }
1011 }
1012
1013 /**
1014  * Run the spill algorithm.
1015  *
1016  * @param birg  the graph to run on
1017  * @param ncls  the register class to run on
1018  */
1019 static void be_spill_belady3(be_irg_t *birg, const arch_register_class_t *ncls)
1020 {
1021         ir_graph *irg = be_get_birg_irg(birg);
1022
1023         cls    = ncls;
1024         n_regs = cls->n_regs - be_put_ignore_regs(birg, cls, NULL);
1025
1026         /* shortcut for register classes with ignore regs only */
1027         if (n_regs == 0)
1028                 return;
1029
1030         worklist_visited = 0;
1031         exec_freq        = be_get_birg_exec_freq(birg);
1032
1033         be_clear_links(irg);
1034         ir_reserve_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK
1035                         | IR_RESOURCE_LOOP_LINK);
1036         inc_irg_visited(irg);
1037
1038         obstack_init(&obst);
1039         senv = be_new_spill_env(birg);
1040
1041         assure_cf_loop(irg);
1042         clear_loop_info(get_irg_loop(irg));
1043         irg_block_walk_graph(irg, construct_loop_edges, NULL, NULL);
1044
1045         process_loop(get_irg_loop(irg));
1046
1047         irg_block_walk_graph(irg, fix_block_borders, NULL, NULL);
1048
1049         ir_free_resources(irg, IR_RESOURCE_IRN_VISITED | IR_RESOURCE_IRN_LINK
1050                         | IR_RESOURCE_LOOP_LINK);
1051
1052         be_insert_spills_reloads(senv);
1053
1054         obstack_free(&obst, NULL);
1055
1056         /* clean up */
1057         be_delete_spill_env(senv);
1058 }
1059
1060 void be_init_spillbelady3(void)
1061 {
1062         static be_spiller_t belady3_spiller = {
1063                 be_spill_belady3
1064         };
1065
1066         be_register_spiller("belady3", &belady3_spiller);
1067         FIRM_DBG_REGISTER(dbg, "firm.be.spill.belady3");
1068 }
1069
1070 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_spillbelady3);