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

   1 /*
   2  * Copyright (C) 1995-2011 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       Beladys spillalgorithm.
  23  * @author      Daniel Grund, Matthias Braun
  24  * @date        20.09.2005
  25  */
  26 #include "config.h"
  27
  28 #include <stdbool.h>
  29
  30 #include "obst.h"
  31 #include "irgraph.h"
  32 #include "irnode.h"
  33 #include "irmode.h"
  34 #include "irgwalk.h"
  35 #include "irloop.h"
  36 #include "iredges_t.h"
  37 #include "ircons_t.h"
  38 #include "irprintf.h"
  39 #include "irnodeset.h"
  40 #include "irtools.h"
  41 #include "statev_t.h"
  42 #include "util.h"
  43
  44 #include "beutil.h"
  45 #include "bearch.h"
  46 #include "beuses.h"
  47 #include "besched.h"
  48 #include "beirgmod.h"
  49 #include "belive_t.h"
  50 #include "benode.h"
  51 #include "bechordal_t.h"
  52 #include "bespill.h"
  53 #include "beloopana.h"
  54 #include "beirg.h"
  55 #include "bespillutil.h"
  56 #include "bemodule.h"
  57
  58 #define DBG_SPILL     1
  59 #define DBG_WSETS     2
  60 #define DBG_FIX       4
  61 #define DBG_DECIDE    8
  62 #define DBG_START    16
  63 #define DBG_SLOTS    32
  64 #define DBG_TRACE    64
  65 #define DBG_WORKSET 128
  66 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  67
  68 #define TIME_UNDEFINED 6666
  69
  70 /**
  71  * An association between a node and a point in time.
  72  */
  73 typedef struct loc_t {
  74         ir_node          *node;
  75         unsigned          time;     /**< A use time (see beuses.h). */
  76         bool              spilled;  /**< value was already spilled on this path */
  77 } loc_t;
  78
  79 typedef struct workset_t {
  80         unsigned len;     /**< current length */
  81         loc_t    vals[];  /**< array of the values/distances in this working set */
  82 } workset_t;
  83
  84 static struct obstack               obst;
  85 static const arch_register_class_t *cls;
  86 static const be_lv_t               *lv;
  87 static be_loopana_t                *loop_ana;
  88 static unsigned                     n_regs;
  89 static workset_t                   *ws;     /**< the main workset used while
  90                                                      processing a block. */
  91 static be_uses_t                   *uses;   /**< env for the next-use magic */
  92 static ir_node                     *instr;  /**< current instruction */
  93 static spill_env_t                 *senv;   /**< see bespill.h */
  94 static ir_node                    **blocklist;
  95
  96 static int                          move_spills      = true;
  97 static int                          respectloopdepth = true;
  98 static int                          improve_known_preds = true;
  99 /* factor to weight the different costs of reloading/rematerializing a node
 100    (see bespill.h be_get_reload_costs_no_weight) */
 101 static int                          remat_bonus      = 10;
 102
 103 static const lc_opt_table_entry_t options[] = {
 104         LC_OPT_ENT_BOOL   ("movespills", "try to move spills out of loops", &move_spills),
 105         LC_OPT_ENT_BOOL   ("respectloopdepth", "outermost loop cutting", &respectloopdepth),
 106         LC_OPT_ENT_BOOL   ("improveknownpreds", "known preds cutting", &improve_known_preds),
 107         LC_OPT_ENT_INT    ("rematbonus", "give bonus to rematerialisable nodes", &remat_bonus),
 108         LC_OPT_LAST
 109 };
 110
 111 /**
 112  * Alloc a new workset on obstack @p ob with maximum size @p max
 113  */
 114 static workset_t *new_workset(void)
 115 {
 116         return OALLOCFZ(&obst, workset_t, vals, n_regs);
 117 }
 118
 119 /**
 120  * Alloc a new instance on obstack and make it equal to @param workset
 121  */
 122 static workset_t *workset_clone(workset_t *workset)
 123 {
 124         workset_t *res = OALLOCF(&obst, workset_t, vals, n_regs);
 125         memcpy(res, workset, sizeof(*res) + n_regs * sizeof(res->vals[0]));
 126         return res;
 127 }
 128
 129 /**
 130  * Copy workset @param src to @param tgt
 131  */
 132 static void workset_copy(workset_t *dest, const workset_t *src)
 133 {
 134         size_t size = sizeof(*src) + n_regs * sizeof(src->vals[0]);
 135         memcpy(dest, src, size);
 136 }
 137
 138 /**
 139  * Overwrites the current content array of @param ws with the
 140  * @param count locations given at memory @param locs.
 141  * Set the length of @param ws to count.
 142  */
 143 static void workset_bulk_fill(workset_t *workset, int count, const loc_t *locs)
 144 {
 145         workset->len = count;
 146         memcpy(&(workset->vals[0]), locs, count * sizeof(locs[0]));
 147 }
 148
 149 /**
 150  * Inserts the value @p val into the workset, iff it is not
 151  * already contained. The workset must not be full.
 152  */
 153 static void workset_insert(workset_t *workset, ir_node *val, bool spilled)
 154 {
 155         loc_t    *loc;
 156         unsigned  i;
 157         /* check for current regclass */
 158         assert(arch_irn_consider_in_reg_alloc(cls, val));
 159
 160         /* check if val is already contained */
 161         for (i = 0; i < workset->len; ++i) {
 162                 loc = &workset->vals[i];
 163                 if (loc->node == val) {
 164                         if (spilled) {
 165                                 loc->spilled = true;
 166                         }
 167                         return;
 168                 }
 169         }
 170
 171         /* insert val */
 172         assert(workset->len < n_regs && "Workset already full!");
 173         loc           = &workset->vals[workset->len];
 174         loc->node     = val;
 175         loc->spilled  = spilled;
 176         loc->time     = TIME_UNDEFINED;
 177         workset->len++;
 178 }
 179
 180 /**
 181  * Removes all entries from this workset
 182  */
 183 static void workset_clear(workset_t *workset)
 184 {
 185         workset->len = 0;
 186 }
 187
 188 /**
 189  * Removes the value @p val from the workset if present.
 190  */
 191 static void workset_remove(workset_t *workset, ir_node *val)
 192 {
 193         unsigned i;
 194         for (i = 0; i < workset->len; ++i) {
 195                 if (workset->vals[i].node == val) {
 196                         workset->vals[i] = workset->vals[--workset->len];
 197                         return;
 198                 }
 199         }
 200 }
 201
 202 static const loc_t *workset_contains(const workset_t *ws, const ir_node *val)
 203 {
 204         unsigned i;
 205         for (i = 0; i < ws->len; ++i) {
 206                 if (ws->vals[i].node == val)
 207                         return &ws->vals[i];
 208         }
 209
 210         return NULL;
 211 }
 212
 213 static int loc_compare(const void *a, const void *b)
 214 {
 215         const loc_t   *p  = ((const loc_t*) a);
 216         const loc_t   *q  = ((const loc_t*) b);
 217         const unsigned pt = p->time;
 218         const unsigned qt = q->time;
 219
 220         if (pt < qt)
 221                 return -1;
 222         if (pt > qt)
 223                 return 1;
 224
 225         return get_irn_node_nr(p->node) - get_irn_node_nr(q->node);
 226 }
 227
 228 static void workset_sort(workset_t *workset)
 229 {
 230         qsort(workset->vals, workset->len, sizeof(workset->vals[0]), loc_compare);
 231 }
 232
 233 static inline unsigned workset_get_time(const workset_t *workset, unsigned idx)
 234 {
 235         return workset->vals[idx].time;
 236 }
 237
 238 static inline void workset_set_time(workset_t *workset, unsigned idx,
 239                                     unsigned time)
 240 {
 241         workset->vals[idx].time = time;
 242 }
 243
 244 static inline unsigned workset_get_length(const workset_t *workset)
 245 {
 246         return workset->len;
 247 }
 248
 249 static inline void workset_set_length(workset_t *workset, unsigned len)
 250 {
 251         workset->len = len;
 252 }
 253
 254 static inline ir_node *workset_get_val(const workset_t *workset, unsigned idx)
 255 {
 256         return workset->vals[idx].node;
 257 }
 258
 259 /**
 260  * Iterates over all values in the working set.
 261  * @p ws The workset to iterate
 262  * @p v  A variable to put the current value in
 263  * @p i  An integer for internal use
 264  */
 265 #define workset_foreach(ws, v, i) \
 266         for (i=0; v=(i < ws->len) ? ws->vals[i].node : NULL, i < ws->len; ++i)
 267
 268 typedef struct block_info_t {
 269         workset_t *start_workset;
 270         workset_t *end_workset;
 271 } block_info_t;
 272
 273 static block_info_t *new_block_info(void)
 274 {
 275         return OALLOCZ(&obst, block_info_t);
 276 }
 277
 278 static inline block_info_t *get_block_info(const ir_node *block)
 279 {
 280         return (block_info_t*)get_irn_link(block);
 281 }
 282
 283 static inline void set_block_info(ir_node *block, block_info_t *info)
 284 {
 285         set_irn_link(block, info);
 286 }
 287
 288 /**
 289  * @return The distance to the next use or 0 if irn has dont_spill flag set
 290  */
 291 static unsigned get_distance(ir_node *from, const ir_node *def, int skip_from_uses)
 292 {
 293         be_next_use_t use;
 294         unsigned      costs;
 295         unsigned      time;
 296
 297         assert(!arch_irn_is_ignore(def));
 298
 299         use  = be_get_next_use(uses, from, def, skip_from_uses);
 300         time = use.time;
 301         if (USES_IS_INFINITE(time))
 302                 return USES_INFINITY;
 303
 304         /* We have to keep nonspillable nodes in the workingset */
 305         if (arch_get_irn_flags(skip_Proj_const(def)) & arch_irn_flags_dont_spill)
 306                 return 0;
 307
 308         /* give some bonus to rematerialisable nodes */
 309         if (remat_bonus > 0) {
 310                 costs = be_get_reload_costs_no_weight(senv, def, use.before);
 311                 assert(costs * remat_bonus < 1000);
 312                 time  += 1000 - (costs * remat_bonus);
 313         }
 314
 315         return time;
 316 }
 317
 318 /**
 319  * Performs the actions necessary to grant the request that:
 320  * - new_vals can be held in registers
 321  * - as few as possible other values are disposed
 322  * - the worst values get disposed
 323  *
 324  * @p is_usage indicates that the values in new_vals are used (not defined)
 325  * In this case reloads must be performed
 326  */
 327 static void displace(workset_t *new_vals, int is_usage)
 328 {
 329         ir_node **to_insert = ALLOCAN(ir_node*, n_regs);
 330         bool     *spilled   = ALLOCAN(bool,     n_regs);
 331         ir_node  *val;
 332         int       i;
 333         int       len;
 334         int       spills_needed;
 335         int       demand;
 336         unsigned  iter;
 337
 338         /* 1. Identify the number of needed slots and the values to reload */
 339         demand = 0;
 340         workset_foreach(new_vals, val, iter) {
 341                 bool reloaded = false;
 342
 343                 if (! workset_contains(ws, val)) {
 344                         DB((dbg, DBG_DECIDE, "    insert %+F\n", val));
 345                         if (is_usage) {
 346                                 DB((dbg, DBG_SPILL, "Reload %+F before %+F\n", val, instr));
 347                                 be_add_reload(senv, val, instr, cls, 1);
 348                                 reloaded = true;
 349                         }
 350                 } else {
 351                         DB((dbg, DBG_DECIDE, "    %+F already in workset\n", val));
 352                         assert(is_usage);
 353                         /* remove the value from the current workset so it is not accidently
 354                          * spilled */
 355                         workset_remove(ws, val);
 356                 }
 357                 spilled[demand]   = reloaded;
 358                 to_insert[demand] = val;
 359                 ++demand;
 360         }
 361
 362         /* 2. Make room for at least 'demand' slots */
 363         len           = workset_get_length(ws);
 364         spills_needed = len + demand - n_regs;
 365         assert(spills_needed <= len);
 366
 367         /* Only make more free room if we do not have enough */
 368         if (spills_needed > 0) {
 369                 DB((dbg, DBG_DECIDE, "    disposing %d values\n", spills_needed));
 370
 371                 /* calculate current next-use distance for live values */
 372                 for (i = 0; i < len; ++i) {
 373                         ir_node  *val  = workset_get_val(ws, i);
 374                         unsigned  dist = get_distance(instr, val, !is_usage);
 375                         workset_set_time(ws, i, dist);
 376                 }
 377
 378                 /* sort entries by increasing nextuse-distance*/
 379                 workset_sort(ws);
 380
 381                 for (i = len - spills_needed; i < len; ++i) {
 382                         ir_node *val = ws->vals[i].node;
 383
 384                         DB((dbg, DBG_DECIDE, "    disposing node %+F (%u)\n", val,
 385                              workset_get_time(ws, i)));
 386
 387                         if (move_spills) {
 388                                 if (!USES_IS_INFINITE(ws->vals[i].time)
 389                                                 && !ws->vals[i].spilled) {
 390                                         ir_node *after_pos = sched_prev(instr);
 391                                         DB((dbg, DBG_DECIDE, "Spill %+F after node %+F\n", val,
 392                                                 after_pos));
 393                                         be_add_spill(senv, val, after_pos);
 394                                 }
 395                         }
 396                 }
 397
 398                 /* kill the last 'demand' entries in the array */
 399                 workset_set_length(ws, len - spills_needed);
 400         }
 401
 402         /* 3. Insert the new values into the workset */
 403         for (i = 0; i < demand; ++i) {
 404                 ir_node *val = to_insert[i];
 405
 406                 workset_insert(ws, val, spilled[i]);
 407         }
 408 }
 409
 410 enum {
 411         AVAILABLE_EVERYWHERE,
 412         AVAILABLE_NOWHERE,
 413         AVAILABLE_PARTLY,
 414         AVAILABLE_UNKNOWN
 415 };
 416
 417 static unsigned available_in_all_preds(workset_t* const* pred_worksets,
 418                                        size_t n_pred_worksets,
 419                                        const ir_node *value, bool is_local_phi)
 420 {
 421         size_t i;
 422         bool   avail_everywhere = true;
 423         bool   avail_nowhere    = true;
 424
 425         assert(n_pred_worksets > 0);
 426
 427         /* value available in all preds? */
 428         for (i = 0; i < n_pred_worksets; ++i) {
 429                 bool             found     = false;
 430                 const workset_t *p_workset = pred_worksets[i];
 431                 int              p_len     = workset_get_length(p_workset);
 432                 int              p_i;
 433                 const ir_node   *l_value;
 434
 435                 if (is_local_phi) {
 436                         assert(is_Phi(value));
 437                         l_value = get_irn_n(value, i);
 438                 } else {
 439                         l_value = value;
 440                 }
 441
 442                 for (p_i = 0; p_i < p_len; ++p_i) {
 443                         const loc_t *p_l = &p_workset->vals[p_i];
 444                         if (p_l->node != l_value)
 445                                 continue;
 446
 447                         found = true;
 448                         break;
 449                 }
 450
 451                 if (found) {
 452                         avail_nowhere = false;
 453                 } else {
 454                         avail_everywhere = false;
 455                 }
 456         }
 457
 458         if (avail_everywhere) {
 459                 assert(!avail_nowhere);
 460                 return AVAILABLE_EVERYWHERE;
 461         } else if (avail_nowhere) {
 462                 return AVAILABLE_NOWHERE;
 463         } else {
 464                 return AVAILABLE_PARTLY;
 465         }
 466 }
 467
 468 /** Decides whether a specific node should be in the start workset or not
 469  *
 470  * @param env      belady environment
 471  * @param first
 472  * @param node     the node to test
 473  * @param loop     the loop of the node
 474  */
 475 static loc_t to_take_or_not_to_take(ir_node* first, ir_node *node,
 476                                     ir_loop *loop, unsigned available)
 477 {
 478         be_next_use_t next_use;
 479         loc_t         loc;
 480
 481         loc.time    = USES_INFINITY;
 482         loc.node    = node;
 483         loc.spilled = false;
 484
 485         /* We have to keep nonspillable nodes in the workingset */
 486         if (arch_get_irn_flags(skip_Proj_const(node)) & arch_irn_flags_dont_spill) {
 487                 loc.time = 0;
 488                 DB((dbg, DBG_START, "    %+F taken (dontspill node)\n", node, loc.time));
 489                 return loc;
 490         }
 491
 492         next_use = be_get_next_use(uses, first, node, 0);
 493         if (USES_IS_INFINITE(next_use.time)) {
 494                 /* the nodes marked as live in shouldn't be dead, so it must be a phi */
 495                 assert(is_Phi(node));
 496                 loc.time = USES_INFINITY;
 497                 DB((dbg, DBG_START, "    %+F not taken (dead)\n", node));
 498                 return loc;
 499         }
 500
 501         loc.time = next_use.time;
 502
 503         if (improve_known_preds) {
 504                 if (available == AVAILABLE_EVERYWHERE) {
 505                         DB((dbg, DBG_START, "    %+F taken (%u, live in all preds)\n",
 506                             node, loc.time));
 507                         return loc;
 508                 } else if (available == AVAILABLE_NOWHERE) {
 509                         DB((dbg, DBG_START, "    %+F not taken (%u, live in no pred)\n",
 510                             node, loc.time));
 511                         loc.time = USES_INFINITY;
 512                         return loc;
 513                 }
 514         }
 515
 516         if (!respectloopdepth || next_use.outermost_loop >= get_loop_depth(loop)) {
 517                 DB((dbg, DBG_START, "    %+F taken (%u, loop %d)\n", node, loc.time,
 518                     next_use.outermost_loop));
 519         } else {
 520                 loc.time = USES_PENDING;
 521                 DB((dbg, DBG_START, "    %+F delayed (outerdepth %d < loopdepth %d)\n",
 522                     node, next_use.outermost_loop, get_loop_depth(loop)));
 523         }
 524
 525         return loc;
 526 }
 527
 528 /**
 529  * Computes the start-workset for a block with multiple predecessors. We assume
 530  * that at least 1 of the predeccesors is a back-edge which means we're at the
 531  * beginning of a loop. We try to reload as much values as possible now so they
 532  * don't get reloaded inside the loop.
 533  */
 534 static void decide_start_workset(const ir_node *block)
 535 {
 536         ir_loop    *loop = get_irn_loop(block);
 537         ir_node    *first;
 538         loc_t       loc;
 539         loc_t      *starters;
 540         loc_t      *delayed;
 541         unsigned    len;
 542         unsigned    i;
 543         unsigned    ws_count;
 544         int         free_slots, free_pressure_slots;
 545         unsigned    pressure;
 546         int         arity;
 547         workset_t **pred_worksets;
 548         bool        all_preds_known;
 549
 550         /* check predecessors */
 551         arity           = get_irn_arity(block);
 552         pred_worksets   = ALLOCAN(workset_t*, arity);
 553         all_preds_known = true;
 554         for (int in = 0; in < arity; ++in) {
 555                 ir_node      *pred_block = get_Block_cfgpred_block(block, in);
 556                 block_info_t *pred_info  = get_block_info(pred_block);
 557
 558                 if (pred_info == NULL) {
 559                         pred_worksets[in] = NULL;
 560                         all_preds_known   = false;
 561                 } else {
 562                         pred_worksets[in] = pred_info->end_workset;
 563                 }
 564         }
 565
 566         /* Collect all values living at start of block */
 567         starters = NEW_ARR_F(loc_t, 0);
 568         delayed  = NEW_ARR_F(loc_t, 0);
 569
 570         DB((dbg, DBG_START, "Living at start of %+F:\n", block));
 571         first = sched_first(block);
 572
 573         /* check all Phis first */
 574         sched_foreach(block, node) {
 575                 unsigned available;
 576
 577                 if (! is_Phi(node))
 578                         break;
 579                 if (!arch_irn_consider_in_reg_alloc(cls, node))
 580                         continue;
 581
 582                 if (all_preds_known) {
 583                         available = available_in_all_preds(pred_worksets, arity, node, true);
 584                 } else {
 585                         available = AVAILABLE_UNKNOWN;
 586                 }
 587
 588                 loc = to_take_or_not_to_take(first, node, loop, available);
 589
 590                 if (! USES_IS_INFINITE(loc.time)) {
 591                         if (USES_IS_PENDING(loc.time))
 592                                 ARR_APP1(loc_t, delayed, loc);
 593                         else
 594                                 ARR_APP1(loc_t, starters, loc);
 595                 } else {
 596                         be_spill_phi(senv, node);
 597                 }
 598         }
 599
 600         /* check all Live-Ins */
 601         be_lv_foreach_cls(lv, block, be_lv_state_in, cls, node) {
 602                 unsigned available;
 603                 if (all_preds_known) {
 604                         available = available_in_all_preds(pred_worksets, arity, node, false);
 605                 } else {
 606                         available = AVAILABLE_UNKNOWN;
 607                 }
 608
 609                 loc = to_take_or_not_to_take(first, node, loop, available);
 610
 611                 if (! USES_IS_INFINITE(loc.time)) {
 612                         if (USES_IS_PENDING(loc.time))
 613                                 ARR_APP1(loc_t, delayed, loc);
 614                         else
 615                                 ARR_APP1(loc_t, starters, loc);
 616                 }
 617         }
 618
 619         pressure            = be_get_loop_pressure(loop_ana, cls, loop);
 620         assert(ARR_LEN(delayed) <= pressure);
 621         free_slots          = n_regs - ARR_LEN(starters);
 622         free_pressure_slots = n_regs - (pressure - ARR_LEN(delayed));
 623         free_slots          = MIN(free_slots, free_pressure_slots);
 624
 625         /* so far we only put nodes into the starters list that are used inside
 626          * the loop. If register pressure in the loop is low then we can take some
 627          * values and let them live through the loop */
 628         DB((dbg, DBG_START, "Loop pressure %d, taking %d delayed vals\n",
 629             pressure, free_slots));
 630         if (free_slots > 0) {
 631                 size_t i;
 632
 633                 qsort(delayed, ARR_LEN(delayed), sizeof(delayed[0]), loc_compare);
 634
 635                 for (i = 0; i < ARR_LEN(delayed) && free_slots > 0; ++i) {
 636                         int    p, arity;
 637                         loc_t *loc = & delayed[i];
 638
 639                         if (!is_Phi(loc->node)) {
 640                                 /* don't use values which are dead in a known predecessors
 641                                  * to not induce unnecessary reloads */
 642                                 arity = get_irn_arity(block);
 643                                 for (p = 0; p < arity; ++p) {
 644                                         ir_node      *pred_block = get_Block_cfgpred_block(block, p);
 645                                         block_info_t *pred_info  = get_block_info(pred_block);
 646
 647                                         if (pred_info == NULL)
 648                                                 continue;
 649
 650                                         if (!workset_contains(pred_info->end_workset, loc->node)) {
 651                                                 DB((dbg, DBG_START,
 652                                                         "    delayed %+F not live at pred %+F\n", loc->node,
 653                                                         pred_block));
 654                                                 goto skip_delayed;
 655                                         }
 656                                 }
 657                         }
 658
 659                         DB((dbg, DBG_START, "    delayed %+F taken\n", loc->node));
 660                         ARR_APP1(loc_t, starters, *loc);
 661                         loc->node = NULL;
 662                         --free_slots;
 663                 skip_delayed:
 664                         ;
 665                 }
 666         }
 667
 668         /* spill phis (the actual phis not just their values) that are in this block
 669          * but not in the start workset */
 670         len = ARR_LEN(delayed);
 671         for (i = 0; i < len; ++i) {
 672                 ir_node *node = delayed[i].node;
 673                 if (node == NULL || !is_Phi(node) || get_nodes_block(node) != block)
 674                         continue;
 675
 676                 DB((dbg, DBG_START, "    spilling delayed phi %+F\n", node));
 677                 be_spill_phi(senv, node);
 678         }
 679         DEL_ARR_F(delayed);
 680
 681         /* Sort start values by first use */
 682         qsort(starters, ARR_LEN(starters), sizeof(starters[0]), loc_compare);
 683
 684         /* Copy the best ones from starters to start workset */
 685         ws_count = MIN((unsigned) ARR_LEN(starters), n_regs);
 686         workset_clear(ws);
 687         workset_bulk_fill(ws, ws_count, starters);
 688
 689         /* spill phis (the actual phis not just their values) that are in this block
 690          * but not in the start workset */
 691         len = ARR_LEN(starters);
 692         for (i = ws_count; i < len; ++i) {
 693                 ir_node *node = starters[i].node;
 694                 if (! is_Phi(node) || get_nodes_block(node) != block)
 695                         continue;
 696
 697                 DB((dbg, DBG_START, "    spilling phi %+F\n", node));
 698                 be_spill_phi(senv, node);
 699         }
 700
 701         DEL_ARR_F(starters);
 702
 703         /* determine spill status of the values: If there's 1 pred block (which
 704          * is no backedge) where the value is spilled then we must set it to
 705          * spilled here. */
 706         for (i = 0; i < ws_count; ++i) {
 707                 loc_t   *loc     = &ws->vals[i];
 708                 ir_node *value   = loc->node;
 709                 bool     spilled;
 710                 int      n;
 711
 712                 /* phis from this block aren't spilled */
 713                 if (get_nodes_block(value) == block) {
 714                         assert(is_Phi(value));
 715                         loc->spilled = false;
 716                         continue;
 717                 }
 718
 719                 /* determine if value was spilled on any predecessor */
 720                 spilled = false;
 721                 for (n = 0; n < arity; ++n) {
 722                         workset_t *pred_workset = pred_worksets[n];
 723                         int        p_len;
 724                         int        p;
 725
 726                         if (pred_workset == NULL)
 727                                 continue;
 728
 729                         p_len = workset_get_length(pred_workset);
 730                         for (p = 0; p < p_len; ++p) {
 731                                 loc_t *l = &pred_workset->vals[p];
 732
 733                                 if (l->node != value)
 734                                         continue;
 735
 736                                 if (l->spilled) {
 737                                         spilled = true;
 738                                 }
 739                                 break;
 740                         }
 741                 }
 742
 743                 loc->spilled = spilled;
 744         }
 745 }
 746
 747 /**
 748  * For the given block @p block, decide for each values
 749  * whether it is used from a register or is reloaded
 750  * before the use.
 751  */
 752 static void process_block(ir_node *block)
 753 {
 754         workset_t    *new_vals;
 755         unsigned      iter;
 756         block_info_t *block_info;
 757         int           arity;
 758
 759         /* no need to process a block twice */
 760         assert(get_block_info(block) == NULL);
 761
 762         /* construct start workset */
 763         arity = get_Block_n_cfgpreds(block);
 764         if (arity == 0) {
 765                 /* no predecessor -> empty set */
 766                 workset_clear(ws);
 767         } else if (arity == 1) {
 768                 /* one predecessor, copy its end workset */
 769                 ir_node      *pred_block = get_Block_cfgpred_block(block, 0);
 770                 block_info_t *pred_info  = get_block_info(pred_block);
 771
 772                 assert(pred_info != NULL);
 773                 workset_copy(ws, pred_info->end_workset);
 774         } else {
 775                 /* multiple predecessors, do more advanced magic :) */
 776                 decide_start_workset(block);
 777         }
 778
 779         DB((dbg, DBG_DECIDE, "\n"));
 780         DB((dbg, DBG_DECIDE, "Decide for %+F\n", block));
 781
 782         block_info = new_block_info();
 783         set_block_info(block, block_info);
 784
 785         DB((dbg, DBG_WSETS, "Start workset for %+F:\n", block));
 786         {
 787                 ir_node *irn;
 788                 workset_foreach(ws, irn, iter) {
 789                         DB((dbg, DBG_WSETS, "  %+F (%u)\n", irn, workset_get_time(ws, iter)));
 790                 }
 791         }
 792
 793         block_info->start_workset = workset_clone(ws);
 794
 795         /* process the block from start to end */
 796         DB((dbg, DBG_WSETS, "Processing...\n"));
 797         /* TODO: this leaks (into the obstack)... */
 798         new_vals = new_workset();
 799
 800         sched_foreach(block, irn) {
 801                 assert(workset_get_length(ws) <= n_regs);
 802
 803                 /* Phis are no real instr (see insert_starters()) */
 804                 if (is_Phi(irn)) {
 805                         continue;
 806                 }
 807                 DB((dbg, DBG_DECIDE, "  ...%+F\n", irn));
 808
 809                 /* set instruction in the workset */
 810                 instr = irn;
 811
 812                 /* allocate all values _used_ by this instruction */
 813                 workset_clear(new_vals);
 814                 be_foreach_use(irn, cls, in_req_, in, in_req,
 815                         /* (note that "spilled" is irrelevant here) */
 816                         workset_insert(new_vals, in, false);
 817                 );
 818                 displace(new_vals, 1);
 819
 820                 /* allocate all values _defined_ by this instruction */
 821                 workset_clear(new_vals);
 822                 be_foreach_definition(irn, cls, value, req,
 823                         assert(req->width == 1);
 824                         workset_insert(new_vals, value, false);
 825                 );
 826                 displace(new_vals, 0);
 827         }
 828
 829         /* Remember end-workset for this block */
 830         block_info->end_workset = workset_clone(ws);
 831         DB((dbg, DBG_WSETS, "End workset for %+F:\n", block));
 832         {
 833                 ir_node *irn;
 834                 workset_foreach(ws, irn, iter)
 835                         DB((dbg, DBG_WSETS, "  %+F (%u)\n", irn, workset_get_time(ws, iter)));
 836         }
 837 }
 838
 839 /**
 840  * 'decide' is block-local and makes assumptions
 841  * about the set of live-ins. Thus we must adapt the
 842  * live-outs to the live-ins at each block-border.
 843  */
 844 static void fix_block_borders(ir_node *block, void *data)
 845 {
 846         workset_t *start_workset;
 847         int        arity;
 848         int        i;
 849         unsigned   iter;
 850         (void) data;
 851
 852         DB((dbg, DBG_FIX, "\n"));
 853         DB((dbg, DBG_FIX, "Fixing %+F\n", block));
 854
 855         arity = get_irn_arity(block);
 856         /* can happen for endless loops */
 857         if (arity == 0)
 858                 return;
 859
 860         start_workset = get_block_info(block)->start_workset;
 861
 862         /* process all pred blocks */
 863         for (i = 0; i < arity; ++i) {
 864                 ir_node   *pred = get_Block_cfgpred_block(block, i);
 865                 workset_t *pred_end_workset = get_block_info(pred)->end_workset;
 866                 ir_node   *node;
 867
 868                 DB((dbg, DBG_FIX, "  Pred %+F\n", pred));
 869
 870                 /* spill all values not used anymore */
 871                 workset_foreach(pred_end_workset, node, iter) {
 872                         ir_node *n2;
 873                         unsigned iter2;
 874                         bool     found = false;
 875                         workset_foreach(start_workset, n2, iter2) {
 876                                 if (n2 == node) {
 877                                         found = true;
 878                                         break;
 879                                 }
 880                                 /* note that we do not look at phi inputs, becuase the values
 881                                  * will be either live-end and need no spill or
 882                                  * they have other users in which must be somewhere else in the
 883                                  * workset */
 884                         }
 885
 886                         if (found)
 887                                 continue;
 888
 889                         if (move_spills && be_is_live_in(lv, block, node)
 890                                         && !pred_end_workset->vals[iter].spilled) {
 891                                 ir_node *insert_point;
 892                                 if (arity > 1) {
 893                                         insert_point = be_get_end_of_block_insertion_point(pred);
 894                                         insert_point = sched_prev(insert_point);
 895                                 } else {
 896                                         insert_point = block;
 897                                 }
 898                                 DB((dbg, DBG_SPILL, "Spill %+F after %+F\n", node,
 899                                      insert_point));
 900                                 be_add_spill(senv, node, insert_point);
 901                         }
 902                 }
 903
 904                 /* reload missing values in predecessors, add missing spills */
 905                 workset_foreach(start_workset, node, iter) {
 906                         const loc_t *l    = &start_workset->vals[iter];
 907                         const loc_t *pred_loc;
 908
 909                         /* if node is a phi of the current block we reload
 910                          * the corresponding argument, else node itself */
 911                         if (is_Phi(node) && get_nodes_block(node) == block) {
 912                                 node = get_irn_n(node, i);
 913                                 assert(!l->spilled);
 914
 915                                 /* we might have unknowns as argument for the phi */
 916                                 if (!arch_irn_consider_in_reg_alloc(cls, node))
 917                                         continue;
 918                         }
 919
 920                         /* check if node is in a register at end of pred */
 921                         pred_loc = workset_contains(pred_end_workset, node);
 922                         if (pred_loc != NULL) {
 923                                 /* we might have to spill value on this path */
 924                                 if (move_spills && !pred_loc->spilled && l->spilled) {
 925                                         ir_node *insert_point
 926                                                 = be_get_end_of_block_insertion_point(pred);
 927                                         insert_point = sched_prev(insert_point);
 928                                         DB((dbg, DBG_SPILL, "Spill %+F after %+F\n", node,
 929                                             insert_point));
 930                                         be_add_spill(senv, node, insert_point);
 931                                 }
 932                         } else {
 933                                 /* node is not in register at the end of pred -> reload it */
 934                                 DB((dbg, DBG_FIX, "    reload %+F\n", node));
 935                                 DB((dbg, DBG_SPILL, "Reload %+F before %+F,%d\n", node, block, i));
 936                                 be_add_reload_on_edge(senv, node, block, i, cls, 1);
 937                         }
 938                 }
 939         }
 940 }
 941
 942 static void be_spill_belady(ir_graph *irg, const arch_register_class_t *rcls)
 943 {
 944         int i;
 945
 946         be_assure_live_sets(irg);
 947
 948         stat_ev_tim_push();
 949         assure_loopinfo(irg);
 950         stat_ev_tim_pop("belady_time_backedges");
 951
 952         stat_ev_tim_push();
 953         be_clear_links(irg);
 954         stat_ev_tim_pop("belady_time_clear_links");
 955
 956         ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
 957
 958         /* init belady env */
 959         stat_ev_tim_push();
 960         obstack_init(&obst);
 961         cls       = rcls;
 962         lv        = be_get_irg_liveness(irg);
 963         n_regs    = be_get_n_allocatable_regs(irg, cls);
 964         ws        = new_workset();
 965         uses      = be_begin_uses(irg, lv);
 966         loop_ana  = be_new_loop_pressure(irg, cls);
 967         senv      = be_new_spill_env(irg);
 968         blocklist = be_get_cfgpostorder(irg);
 969         stat_ev_tim_pop("belady_time_init");
 970
 971         stat_ev_tim_push();
 972         /* walk blocks in reverse postorder */
 973         for (i = ARR_LEN(blocklist) - 1; i >= 0; --i) {
 974                 process_block(blocklist[i]);
 975         }
 976         DEL_ARR_F(blocklist);
 977         stat_ev_tim_pop("belady_time_belady");
 978
 979         stat_ev_tim_push();
 980         /* belady was block-local, fix the global flow by adding reloads on the
 981          * edges */
 982         irg_block_walk_graph(irg, fix_block_borders, NULL, NULL);
 983         stat_ev_tim_pop("belady_time_fix_borders");
 984
 985         ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
 986
 987         /* Insert spill/reload nodes into the graph and fix usages */
 988         be_insert_spills_reloads(senv);
 989
 990         /* clean up */
 991         be_delete_spill_env(senv);
 992         be_end_uses(uses);
 993         be_free_loop_pressure(loop_ana);
 994         obstack_free(&obst, NULL);
 995 }
 996
 997 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_spillbelady)
 998 void be_init_spillbelady(void)
 999 {
1000         static be_spiller_t belady_spiller = {
1001                 be_spill_belady
1002         };
1003         lc_opt_entry_t *be_grp       = lc_opt_get_grp(firm_opt_get_root(), "be");
1004         lc_opt_entry_t *belady_group = lc_opt_get_grp(be_grp, "belady");
1005         lc_opt_add_table(belady_group, options);
1006
1007         be_register_spiller("belady", &belady_spiller);
1008         FIRM_DBG_REGISTER(dbg, "firm.be.spill.belady");
1009 }