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

   1 /*
   2  * Copyright (C) 1995-2007 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       implementation of the spill/reload placement abstraction layer
  23  * @author      Daniel Grund, Sebastian Hack, Matthias Braun
  24  * @date                29.09.2005
  25  * @version     $Id$
  26  */
  27 #ifdef HAVE_CONFIG_H
  28 #include "config.h"
  29 #endif
  30
  31 #include <stdlib.h>
  32
  33 #include "pset.h"
  34 #include "irnode_t.h"
  35 #include "ircons_t.h"
  36 #include "iredges_t.h"
  37 #include "irbackedge_t.h"
  38 #include "irprintf.h"
  39 #include "ident_t.h"
  40 #include "type_t.h"
  41 #include "entity_t.h"
  42 #include "debug.h"
  43 #include "irgwalk.h"
  44 #include "array.h"
  45 #include "pdeq.h"
  46 #include "execfreq.h"
  47 #include "irnodeset.h"
  48 #include "error.h"
  49
  50 #include "bearch_t.h"
  51 #include "belive_t.h"
  52 #include "besched_t.h"
  53 #include "bespill.h"
  54 #include "belive_t.h"
  55 #include "benode_t.h"
  56 #include "bechordal_t.h"
  57 #include "bejavacoal.h"
  58 #include "benodesets.h"
  59 #include "bespilloptions.h"
  60 #include "bestatevent.h"
  61 #include "bessaconstr.h"
  62 #include "beirg_t.h"
  63 #include "beintlive_t.h"
  64 #include "bemodule.h"
  65
  66 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  67
  68 #define REMAT_COST_INFINITE  1000
  69
  70 typedef struct reloader_t reloader_t;
  71 struct reloader_t {
  72         reloader_t *next;
  73         ir_node    *can_spill_after;
  74         ir_node    *reloader;
  75         ir_node    *rematted_node;
  76         int         remat_cost_delta; /** costs needed for rematerialization,
  77                                            compared to placing a reload */
  78 };
  79
  80 typedef struct spill_t spill_t;
  81 struct spill_t {
  82         spill_t *next;
  83         ir_node *before;   /**< spill has to be placed before this node (or earlier) */
  84         ir_node *spill;
  85 };
  86
  87 typedef struct spill_info_t spill_info_t;
  88 struct spill_info_t {
  89         ir_node    *to_spill;  /**< the value that should get spilled */
  90         reloader_t *reloaders; /**< list of places where the value should get
  91                                     reloaded */
  92         spill_t    *spills;    /**< list of latest places where spill must be
  93                                     placed */
  94         double      spill_costs; /**< costs needed for spilling the value */
  95         const arch_register_class_t *reload_cls; /** the register class in which the
  96                                                      reload should be placed */
  97 };
  98
  99 struct spill_env_t {
 100         const arch_env_t *arch_env;
 101         ir_graph         *irg;
 102         struct obstack    obst;
 103         be_irg_t         *birg;
 104         int               spill_cost;     /**< the cost of a single spill node */
 105         int               reload_cost;    /**< the cost of a reload node */
 106         set              *spills;         /**< all spill_info_t's, which must be
 107                                                placed */
 108         ir_nodeset_t      mem_phis;       /**< set of all spilled phis. */
 109         ir_exec_freq     *exec_freq;
 110
 111 #ifdef FIRM_STATISTICS
 112         unsigned          spill_count;
 113         unsigned          reload_count;
 114         unsigned          remat_count;
 115         unsigned          spilled_phi_count;
 116 #endif
 117 };
 118
 119 /**
 120  * Compare two spill infos.
 121  */
 122 static int cmp_spillinfo(const void *x, const void *y, size_t size)
 123 {
 124         const spill_info_t *xx = x;
 125         const spill_info_t *yy = y;
 126         (void) size;
 127
 128         return xx->to_spill != yy->to_spill;
 129 }
 130
 131 /**
 132  * Returns spill info for a specific value (the value that is to be spilled)
 133  */
 134 static spill_info_t *get_spillinfo(const spill_env_t *env, ir_node *value)
 135 {
 136         spill_info_t info, *res;
 137         int hash = nodeset_hash(value);
 138
 139         info.to_spill = value;
 140         res = set_find(env->spills, &info, sizeof(info), hash);
 141
 142         if (res == NULL) {
 143                 info.reloaders   = NULL;
 144                 info.spills      = NULL;
 145                 info.spill_costs = -1;
 146                 info.reload_cls  = NULL;
 147                 res = set_insert(env->spills, &info, sizeof(info), hash);
 148         }
 149
 150         return res;
 151 }
 152
 153 spill_env_t *be_new_spill_env(be_irg_t *birg)
 154 {
 155         const arch_env_t *arch_env = birg->main_env->arch_env;
 156
 157         spill_env_t *env        = xmalloc(sizeof(env[0]));
 158         env->spills                     = new_set(cmp_spillinfo, 1024);
 159         env->irg            = be_get_birg_irg(birg);
 160         env->birg           = birg;
 161         env->arch_env       = arch_env;
 162         ir_nodeset_init(&env->mem_phis);
 163         env->spill_cost     = arch_env->isa->spill_cost;
 164         env->reload_cost    = arch_env->isa->reload_cost;
 165         env->exec_freq      = be_get_birg_exec_freq(birg);
 166         obstack_init(&env->obst);
 167
 168 #ifdef FIRM_STATISTICS
 169         env->spill_count       = 0;
 170         env->reload_count      = 0;
 171         env->remat_count       = 0;
 172         env->spilled_phi_count = 0;
 173 #endif
 174
 175         return env;
 176 }
 177
 178 void be_delete_spill_env(spill_env_t *env)
 179 {
 180         del_set(env->spills);
 181         ir_nodeset_destroy(&env->mem_phis);
 182         obstack_free(&env->obst, NULL);
 183         free(env);
 184 }
 185
 186 /*
 187  *  ____  _                  ____      _                 _
 188  * |  _ \| | __ _  ___ ___  |  _ \ ___| | ___   __ _  __| |___
 189  * | |_) | |/ _` |/ __/ _ \ | |_) / _ \ |/ _ \ / _` |/ _` / __|
 190  * |  __/| | (_| | (_|  __/ |  _ <  __/ | (_) | (_| | (_| \__ \
 191  * |_|   |_|\__,_|\___\___| |_| \_\___|_|\___/ \__,_|\__,_|___/
 192  *
 193  */
 194
 195 void be_add_spill(spill_env_t *env, ir_node *to_spill, ir_node *before)
 196 {
 197         spill_info_t *spill_info = get_spillinfo(env, to_spill);
 198         spill_t      *spill;
 199         spill_t      *s;
 200         spill_t      *last;
 201
 202         DB((dbg, LEVEL_1, "Add spill of %+F before %+F\n", to_spill, before));
 203
 204         /* spills that are dominated by others are not needed */
 205         last = NULL;
 206         s    = spill_info->spills;
 207         for( ; s != NULL; s = s->next) {
 208                 /* no need to add this spill if it is dominated by another */
 209                 if(value_dominates(s->before, before)) {
 210                         DB((dbg, LEVEL_1, "...dominated by %+F, not added\n", s->before));
 211                         return;
 212                 }
 213                 /* remove spills that we dominate */
 214                 if(value_dominates(before, s->before)) {
 215                         DB((dbg, LEVEL_1, "...remove old spill at %+F\n", s->before));
 216                         if(last != NULL) {
 217                                 last->next         = s->next;
 218                         } else {
 219                                 spill_info->spills = s->next;
 220                         }
 221                 } else {
 222                         last = s;
 223                 }
 224         }
 225
 226         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 227         spill->before = before;
 228         spill->next   = spill_info->spills;
 229         spill->spill  = NULL;
 230
 231         spill_info->spills = spill;
 232 }
 233
 234 void be_add_remat(spill_env_t *env, ir_node *to_spill, ir_node *before,
 235                   ir_node *rematted_node)
 236 {
 237         spill_info_t *spill_info;
 238         reloader_t *reloader;
 239
 240         spill_info = get_spillinfo(env, to_spill);
 241
 242         /* add the remat information */
 243         reloader                   = obstack_alloc(&env->obst, sizeof(reloader[0]));
 244         reloader->next             = spill_info->reloaders;
 245         reloader->reloader         = before;
 246         reloader->rematted_node    = rematted_node;
 247         reloader->remat_cost_delta = 0; /* We will never have a cost win over a
 248                                            reload since we're not even allowed to
 249                                            create a reload */
 250
 251         spill_info->reloaders  = reloader;
 252
 253         DBG((dbg, LEVEL_1, "creating spillinfo for %+F, will be rematerialized before %+F\n",
 254                 to_spill, before));
 255 }
 256
 257 void be_add_reload2(spill_env_t *env, ir_node *to_spill, ir_node *before,
 258                 ir_node *can_spill_after, const arch_register_class_t *reload_cls,
 259                 int allow_remat)
 260 {
 261         spill_info_t *info;
 262         reloader_t *rel;
 263
 264         info = get_spillinfo(env, to_spill);
 265
 266         if (is_Phi(to_spill)) {
 267                 int i, arity;
 268
 269                 /* create spillinfos for the phi arguments */
 270                 for (i = 0, arity = get_irn_arity(to_spill); i < arity; ++i) {
 271                         ir_node *arg = get_irn_n(to_spill, i);
 272                         get_spillinfo(env, arg);
 273                 }
 274         }
 275
 276         assert(!is_Proj(before) && !be_is_Keep(before));
 277
 278         /* put reload into list */
 279         rel                   = obstack_alloc(&env->obst, sizeof(rel[0]));
 280         rel->next             = info->reloaders;
 281         rel->reloader         = before;
 282         rel->rematted_node    = NULL;
 283         rel->can_spill_after  = can_spill_after;
 284         rel->remat_cost_delta = allow_remat ? 0 : REMAT_COST_INFINITE;
 285
 286         info->reloaders  = rel;
 287         assert(info->reload_cls == NULL || info->reload_cls == reload_cls);
 288         info->reload_cls = reload_cls;
 289
 290         DBG((dbg, LEVEL_1, "creating spillinfo for %+F, will be reloaded before %+F, may%s be rematerialized\n",
 291                 to_spill, before, allow_remat ? "" : " not"));
 292 }
 293
 294 void be_add_reload(spill_env_t *senv, ir_node *to_spill, ir_node *before,
 295                    const arch_register_class_t *reload_cls, int allow_remat)
 296 {
 297         be_add_reload2(senv, to_spill, before, to_spill, reload_cls, allow_remat);
 298
 299 }
 300
 301 ir_node *be_get_end_of_block_insertion_point(const ir_node *block)
 302 {
 303         ir_node *last = sched_last(block);
 304
 305         /* we might have keeps behind the jump... */
 306         while(be_is_Keep(last)) {
 307                 last = sched_prev(last);
 308                 assert(!sched_is_end(last));
 309         }
 310
 311         assert(is_cfop(last));
 312
 313         /* add the reload before the (cond-)jump */
 314         return last;
 315 }
 316
 317 /**
 318  * Returns the point at which you can insert a node that should be executed
 319  * before block @p block when coming from pred @p pos.
 320  */
 321 static ir_node *get_block_insertion_point(ir_node *block, int pos)
 322 {
 323         ir_node *predblock;
 324
 325         /* simply add the reload to the beginning of the block if we only have 1
 326          * predecessor. We don't need to check for phis as there can't be any in a
 327          * block with only 1 pred. */
 328         if(get_Block_n_cfgpreds(block) == 1) {
 329                 assert(!is_Phi(sched_first(block)));
 330                 return sched_first(block);
 331         }
 332
 333         /* We have to reload the value in pred-block */
 334         predblock = get_Block_cfgpred_block(block, pos);
 335         return be_get_end_of_block_insertion_point(predblock);
 336 }
 337
 338 void be_add_reload_at_end(spill_env_t *env, ir_node *to_spill,
 339                           const ir_node *block,
 340                           const arch_register_class_t *reload_cls,
 341                           int allow_remat)
 342 {
 343         ir_node *before = be_get_end_of_block_insertion_point(block);
 344         be_add_reload(env, to_spill, before, reload_cls, allow_remat);
 345 }
 346
 347 void be_add_reload_on_edge(spill_env_t *env, ir_node *to_spill, ir_node *block,
 348                            int pos,     const arch_register_class_t *reload_cls,
 349                            int allow_remat)
 350 {
 351         ir_node *before = get_block_insertion_point(block, pos);
 352         be_add_reload(env, to_spill, before, reload_cls, allow_remat);
 353 }
 354
 355 void be_spill_phi(spill_env_t *env, ir_node *node)
 356 {
 357         ir_node *block;
 358         spill_info_t* spill;
 359         int i, arity;
 360
 361         assert(is_Phi(node));
 362
 363         ir_nodeset_insert(&env->mem_phis, node);
 364
 365         /* create spills for the phi arguments */
 366         block = get_nodes_block(node);
 367         spill = get_spillinfo(env, node);
 368         for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
 369                 ir_node *arg        = get_irn_n(node, i);
 370                 ir_node *pred_block = get_Block_cfgpred_block(block, i);
 371                 ir_node *insert     = be_get_end_of_block_insertion_point(pred_block);
 372                 //get_spillinfo(env, arg);
 373                 be_add_spill(env, arg, insert);
 374         }
 375 }
 376
 377 /*
 378  *   ____                _         ____        _ _ _
 379  *  / ___|_ __ ___  __ _| |_ ___  / ___| _ __ (_) | |___
 380  * | |   | '__/ _ \/ _` | __/ _ \ \___ \| '_ \| | | / __|
 381  * | |___| | |  __/ (_| | ||  __/  ___) | |_) | | | \__ \
 382  *  \____|_|  \___|\__,_|\__\___| |____/| .__/|_|_|_|___/
 383  *                                      |_|
 384  */
 385
 386 static ir_node *skip_keeps_phis(ir_node *node)
 387 {
 388         node = sched_next(node);
 389         while(is_Phi(node) || be_is_Keep(node)) {
 390                 node = sched_next(node);
 391         }
 392         return node;
 393 }
 394
 395 static void determine_spill_costs(spill_env_t *env, spill_info_t *spillinfo);
 396
 397 /**
 398  * Creates a spill.
 399  *
 400  * @param senv      the spill environment
 401  * @param irn       the node that should be spilled
 402  * @param ctx_irn   an user of the spilled node
 403  *
 404  * @return a be_Spill node
 405  */
 406 static void spill_irn(spill_env_t *env, spill_info_t *spillinfo)
 407 {
 408         ir_node *to_spill = spillinfo->to_spill;
 409         spill_t *spill;
 410
 411         /* determine_spill_costs must have been run before */
 412         assert(spillinfo->spill_costs >= 0);
 413
 414         /* some backends have virtual noreg/unknown nodes that are not scheduled
 415          * and simply always available. */
 416         if(!sched_is_scheduled(to_spill)) {
 417                 /* override spillinfos or create a new one */
 418                 spillinfo->spills->spill = new_NoMem();
 419                 DB((dbg, LEVEL_1, "don't spill %+F use NoMem\n", to_spill));
 420                 return;
 421         }
 422
 423         DBG((dbg, LEVEL_1, "spilling %+F ... ", to_spill));
 424         spill = spillinfo->spills;
 425         for( ; spill != NULL; spill = spill->next) {
 426                 ir_node *block  = get_block(spill->before);
 427                 ir_node *before = spill->before;
 428
 429                 /* place all spills before the reloads (as we can't guarantee the
 430                  * same order as the be_add_spill and be_add_reload calls */
 431                 while(be_is_Reload(sched_prev(before))) {
 432                         before = sched_prev(before);
 433                 }
 434
 435                 spill->spill    = be_spill(env->arch_env, block, to_spill);
 436                 sched_add_before(before, spill->spill);
 437                 DB((dbg, LEVEL_1, "\t%+F before %+F,", spill->spill, before));
 438 #ifdef FIRM_STATISTICS
 439                 env->spill_count++;
 440 #endif
 441         }
 442         DBG((dbg, LEVEL_1, "\n"));
 443 }
 444
 445 static void spill_node(spill_env_t *env, spill_info_t *spillinfo);
 446
 447 /**
 448  * If the first usage of a Phi result would be out of memory
 449  * there is no sense in allocating a register for it.
 450  * Thus we spill it and all its operands to the same spill slot.
 451  * Therefore the phi/dataB becomes a phi/Memory
 452  *
 453  * @param senv      the spill environment
 454  * @param phi       the Phi node that should be spilled
 455  * @param ctx_irn   an user of the spilled node
 456  */
 457 static void spill_phi(spill_env_t *env, spill_info_t *spillinfo)
 458 {
 459         ir_graph *irg   = env->irg;
 460         ir_node  *phi   = spillinfo->to_spill;
 461         ir_node  *block = get_nodes_block(phi);
 462         ir_node  *unknown;
 463         ir_node **ins;
 464         spill_t  *spill;
 465         int       i;
 466         int       arity;
 467
 468         assert(is_Phi(phi));
 469         assert(!get_opt_cse());
 470         DBG((dbg, LEVEL_1, "spilling Phi %+F:\n", phi));
 471
 472         /* build a new PhiM */
 473         arity   = get_irn_arity(phi);
 474         ins     = alloca(sizeof(ir_node*) * arity);
 475         unknown = new_r_Unknown(irg, mode_M);
 476         for(i = 0; i < arity; ++i) {
 477                 ins[i] = unknown;
 478         }
 479
 480         /* override replace spills... */
 481         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 482         spill->before = skip_keeps_phis(phi);
 483         spill->spill  = new_r_Phi(irg, block, arity, ins, mode_M);
 484         spill->next   = NULL;
 485
 486         spillinfo->spills = spill;
 487 #ifdef FIRM_STATISTICS
 488         env->spilled_phi_count++;
 489 #endif
 490
 491         for(i = 0; i < arity; ++i) {
 492                 ir_node      *arg      = get_irn_n(phi, i);
 493                 spill_info_t *arg_info = get_spillinfo(env, arg);
 494
 495                 determine_spill_costs(env, arg_info);
 496                 spill_node(env, arg_info);
 497
 498                 set_irn_n(spill->spill, i, arg_info->spills->spill);
 499         }
 500         DBG((dbg, LEVEL_1, "... done spilling Phi %+F, created PhiM %+F\n", phi,
 501              spill->spill));
 502 }
 503
 504 /**
 505  * Spill a node.
 506  *
 507  * @param senv      the spill environment
 508  * @param to_spill  the node that should be spilled
 509  */
 510 static void spill_node(spill_env_t *env, spill_info_t *spillinfo)
 511 {
 512         ir_node *to_spill;
 513
 514         /* node is already spilled */
 515         if(spillinfo->spills != NULL && spillinfo->spills->spill != NULL)
 516                 return;
 517
 518         to_spill = spillinfo->to_spill;
 519
 520         if (is_Phi(to_spill) && ir_nodeset_contains(&env->mem_phis, to_spill)) {
 521                 spill_phi(env, spillinfo);
 522         } else {
 523                 spill_irn(env, spillinfo);
 524         }
 525 }
 526
 527 /*
 528  *
 529  *  ____                      _            _       _ _
 530  * |  _ \ ___ _ __ ___   __ _| |_ ___ _ __(_) __ _| (_)_______
 531  * | |_) / _ \ '_ ` _ \ / _` | __/ _ \ '__| |/ _` | | |_  / _ \
 532  * |  _ <  __/ | | | | | (_| | ||  __/ |  | | (_| | | |/ /  __/
 533  * |_| \_\___|_| |_| |_|\__,_|\__\___|_|  |_|\__,_|_|_/___\___|
 534  *
 535  */
 536
 537 /**
 538  * Tests whether value @p arg is available before node @p reloader
 539  * @returns 1 if value is available, 0 otherwise
 540  */
 541 static int is_value_available(spill_env_t *env, const ir_node *arg,
 542                               const ir_node *reloader)
 543 {
 544         if(is_Unknown(arg) || arg == new_NoMem())
 545                 return 1;
 546
 547         if(be_is_Spill(arg))
 548                 return 1;
 549
 550         if(arg == get_irg_frame(env->irg))
 551                 return 1;
 552
 553         /* hack for now (happens when command should be inserted at end of block) */
 554         if(is_Block(reloader)) {
 555                 return 0;
 556         }
 557
 558         /*
 559          * Ignore registers are always available
 560          */
 561         if(arch_irn_is(env->arch_env, arg, ignore)) {
 562                 return 1;
 563         }
 564
 565         /* the following test does not work while spilling,
 566          * because the liveness info is not adapted yet to the effects of the
 567          * additional spills/reloads.
 568          */
 569 #if 0
 570         /* we want to remat before the insn reloader
 571          * thus an arguments is alive if
 572          *   - it interferes with the reloaders result
 573          *   - or it is (last-) used by reloader itself
 574          */
 575         if (values_interfere(env->birg->lv, reloader, arg)) {
 576                 return 1;
 577         }
 578
 579         arity = get_irn_arity(reloader);
 580         for (i = 0; i < arity; ++i) {
 581                 ir_node *rel_arg = get_irn_n(reloader, i);
 582                 if (rel_arg == arg)
 583                         return 1;
 584         }
 585 #endif
 586
 587         return 0;
 588 }
 589
 590 /**
 591  * Checks whether the node can principally be rematerialized
 592  */
 593 static int is_remat_node(spill_env_t *env, const ir_node *node)
 594 {
 595         const arch_env_t *arch_env = env->arch_env;
 596
 597         assert(!be_is_Spill(node));
 598
 599         if(arch_irn_is(arch_env, node, rematerializable))
 600                 return 1;
 601
 602         return 0;
 603 }
 604
 605 /**
 606  * Check if a node is rematerializable. This tests for the following conditions:
 607  *
 608  * - The node itself is rematerializable
 609  * - All arguments of the node are available or also rematerialisable
 610  * - The costs for the rematerialisation operation is less or equal a limit
 611  *
 612  * Returns the costs needed for rematerialisation or something
 613  * >= REMAT_COST_INFINITE if remat is not possible.
 614  */
 615 static int check_remat_conditions_costs(spill_env_t *env,
 616                 const ir_node *spilled, const ir_node *reloader, int parentcosts)
 617 {
 618         int i, arity;
 619         int argremats;
 620         int costs = 0;
 621
 622         if(!is_remat_node(env, spilled))
 623                 return REMAT_COST_INFINITE;
 624
 625         if(be_is_Reload(spilled)) {
 626                 costs += 2;
 627         } else {
 628                 costs += arch_get_op_estimated_cost(env->arch_env, spilled);
 629         }
 630         if(parentcosts + costs >= env->reload_cost + env->spill_cost) {
 631                 return REMAT_COST_INFINITE;
 632         }
 633         if(arch_irn_is(env->arch_env, spilled, modify_flags)) {
 634                 return REMAT_COST_INFINITE;
 635         }
 636
 637         argremats = 0;
 638         for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
 639                 ir_node *arg = get_irn_n(spilled, i);
 640
 641                 if(is_value_available(env, arg, reloader))
 642                         continue;
 643
 644                 /* we have to rematerialize the argument as well */
 645                 if(argremats >= 1) {
 646                         /* we only support rematerializing 1 argument at the moment,
 647                          * so that we don't have to care about register pressure
 648                          */
 649                         return REMAT_COST_INFINITE;
 650                 }
 651                 argremats++;
 652
 653                 costs += check_remat_conditions_costs(env, arg, reloader,
 654                                                       parentcosts + costs);
 655                 if(parentcosts + costs >= env->reload_cost + env->spill_cost)
 656                         return REMAT_COST_INFINITE;
 657         }
 658
 659         return costs;
 660 }
 661
 662 /**
 663  * Re-materialize a node.
 664  *
 665  * @param senv      the spill environment
 666  * @param spilled   the node that was spilled
 667  * @param reloader  a irn that requires a reload
 668  */
 669 static ir_node *do_remat(spill_env_t *env, ir_node *spilled, ir_node *reloader)
 670 {
 671         int i, arity;
 672         ir_node *res;
 673         ir_node *bl;
 674         ir_node **ins;
 675
 676         if(is_Block(reloader)) {
 677                 bl = reloader;
 678         } else {
 679                 bl = get_nodes_block(reloader);
 680         }
 681
 682         ins = alloca(get_irn_arity(spilled) * sizeof(ins[0]));
 683         for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
 684                 ir_node *arg = get_irn_n(spilled, i);
 685
 686                 if(is_value_available(env, arg, reloader)) {
 687                         ins[i] = arg;
 688                 } else {
 689                         ins[i] = do_remat(env, arg, reloader);
 690 #ifdef FIRM_STATISTICS
 691                         /* don't count the recursive call as remat */
 692                         env->remat_count--;
 693 #endif
 694                 }
 695         }
 696
 697         /* create a copy of the node */
 698         res = new_ir_node(get_irn_dbg_info(spilled), env->irg, bl,
 699                           get_irn_op(spilled), get_irn_mode(spilled),
 700                           get_irn_arity(spilled), ins);
 701         copy_node_attr(spilled, res);
 702         new_backedge_info(res);
 703
 704         DBG((dbg, LEVEL_1, "Insert remat %+F of %+F before reloader %+F\n", res, spilled, reloader));
 705
 706         if (! is_Proj(res)) {
 707                 /* insert in schedule */
 708                 sched_reset(res);
 709                 sched_add_before(reloader, res);
 710 #ifdef FIRM_STATISTICS
 711                 env->remat_count++;
 712 #endif
 713         }
 714
 715         return res;
 716 }
 717
 718 double be_get_spill_costs(spill_env_t *env, ir_node *to_spill, ir_node *before)
 719 {
 720         ir_node *block = get_nodes_block(before);
 721         double   freq  = get_block_execfreq(env->exec_freq, block);
 722         (void) to_spill;
 723
 724         return env->spill_cost * freq;
 725 }
 726
 727 double be_get_reload_costs(spill_env_t *env, ir_node *to_spill, ir_node *before)
 728 {
 729         ir_node      *block = get_nodes_block(before);
 730         double        freq  = get_block_execfreq(env->exec_freq, block);
 731
 732         if(be_do_remats) {
 733                 /* is the node rematerializable? */
 734                 int costs = check_remat_conditions_costs(env, to_spill, before, 0);
 735                 if(costs < env->reload_cost)
 736                         return costs * freq;
 737         }
 738
 739         return env->reload_cost * freq;
 740 }
 741
 742 int be_is_rematerializable(spill_env_t *env, const ir_node *to_remat,
 743                            const ir_node *before)
 744 {
 745         return check_remat_conditions_costs(env, to_remat, before, 0) < REMAT_COST_INFINITE;
 746 }
 747
 748 double be_get_reload_costs_on_edge(spill_env_t *env, ir_node *to_spill,
 749                                    ir_node *block, int pos)
 750 {
 751         ir_node *before = get_block_insertion_point(block, pos);
 752         return be_get_reload_costs(env, to_spill, before);
 753 }
 754
 755 /*
 756  *  ___                     _     ____      _                 _
 757  * |_ _|_ __  ___  ___ _ __| |_  |  _ \ ___| | ___   __ _  __| |___
 758  *  | || '_ \/ __|/ _ \ '__| __| | |_) / _ \ |/ _ \ / _` |/ _` / __|
 759  *  | || | | \__ \  __/ |  | |_  |  _ <  __/ | (_) | (_| | (_| \__ \
 760  * |___|_| |_|___/\___|_|   \__| |_| \_\___|_|\___/ \__,_|\__,_|___/
 761  *
 762  */
 763
 764 /**
 765  * analyzes how to best spill a node and determine costs for that
 766  */
 767 static void determine_spill_costs(spill_env_t *env, spill_info_t *spillinfo)
 768 {
 769         ir_node *to_spill = spillinfo->to_spill;
 770         ir_node *spill_block;
 771         spill_t *spill;
 772         double   spill_execfreq;
 773
 774         /* already calculated? */
 775         if(spillinfo->spill_costs >= 0)
 776                 return;
 777
 778         assert(! arch_irn_is(env->arch_env, to_spill, dont_spill));
 779         assert(!be_is_Reload(to_spill));
 780
 781         /* some backends have virtual noreg/unknown nodes that are not scheduled
 782          * and simply always available.
 783          * TODO: this is kinda hairy, the NoMem is correct for an Unknown as Phi
 784          * predecessor (of a PhiM) but this test might match other things too...
 785          */
 786         if(!sched_is_scheduled(to_spill)) {
 787                 /* override spillinfos or create a new one */
 788                 spill_t *spill = obstack_alloc(&env->obst, sizeof(spill[0]));
 789                 spill->before  = NULL;
 790                 spill->next    = NULL;
 791                 spill->spill   = new_NoMem();
 792
 793                 spillinfo->spills      = spill;
 794                 spillinfo->spill_costs = 0;
 795
 796                 DB((dbg, LEVEL_1, "don't spill %+F use NoMem\n", to_spill));
 797                 return;
 798         }
 799
 800         spill_block    = get_nodes_block(to_spill);
 801         spill_execfreq = get_block_execfreq(env->exec_freq, spill_block);
 802
 803         if (is_Phi(to_spill) && ir_nodeset_contains(&env->mem_phis, to_spill)) {
 804                 /* TODO calculate correct costs...
 805                  * (though we can't remat this node anyway so no big problem) */
 806                 spillinfo->spill_costs = env->spill_cost * spill_execfreq;
 807                 return;
 808         }
 809
 810         if(spillinfo->spills != NULL) {
 811                 spill_t *s;
 812                 double   spills_execfreq;
 813
 814                 /* calculate sum of executaion frequencies of individual spills */
 815                 spills_execfreq = 0;
 816                 s               = spillinfo->spills;
 817                 for( ; s != NULL; s = s->next) {
 818                         ir_node *spill_block = s->before;
 819                         double   freq;
 820
 821                         if(!is_Block(spill_block)) {
 822                                 spill_block = get_nodes_block(spill_block);
 823                         }
 824                         freq = get_block_execfreq(env->exec_freq, spill_block);
 825
 826                         spills_execfreq += freq;
 827                 }
 828
 829                 DB((dbg, LEVEL_1, "%+F: latespillcosts %f after def: %f\n", to_spill,
 830                     spills_execfreq * env->spill_cost,
 831                     spill_execfreq * env->spill_cost));
 832
 833                 /* multi-/latespill is advantageous -> return*/
 834                 if(spills_execfreq < spill_execfreq) {
 835                         DB((dbg, LEVEL_1, "use latespills for %+F\n", to_spill));
 836                         spillinfo->spill_costs = spills_execfreq * env->spill_cost;
 837                         return;
 838                 }
 839         }
 840
 841         /* override spillinfos or create a new one */
 842         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 843         spill->before = skip_keeps_phis(to_spill);
 844         spill->next   = NULL;
 845         spill->spill  = NULL;
 846
 847         spillinfo->spills      = spill;
 848         spillinfo->spill_costs = spill_execfreq * env->spill_cost;
 849         DB((dbg, LEVEL_1, "spill %+F after definition\n", to_spill));
 850 }
 851
 852 void be_insert_spills_reloads(spill_env_t *env)
 853 {
 854         const arch_env_t      *arch_env  = env->arch_env;
 855         const ir_exec_freq    *exec_freq = env->exec_freq;
 856         spill_info_t          *si;
 857         ir_nodeset_iterator_t  iter;
 858         ir_node               *node;
 859
 860         /* create all phi-ms first, this is needed so, that phis, hanging on
 861            spilled phis work correctly */
 862         foreach_ir_nodeset(&env->mem_phis, node, iter) {
 863                 spill_info_t *info = get_spillinfo(env, node);
 864                 spill_node(env, info);
 865         }
 866
 867         /* process each spilled node */
 868         for (si = set_first(env->spills); si; si = set_next(env->spills)) {
 869                 reloader_t *rld;
 870                 ir_node  *to_spill        = si->to_spill;
 871                 ir_mode  *mode            = get_irn_mode(to_spill);
 872                 ir_node **copies          = NEW_ARR_F(ir_node*, 0);
 873                 double    all_remat_costs = 0; /** costs when we would remat all nodes */
 874                 int       force_remat     = 0;
 875
 876                 DBG((dbg, LEVEL_1, "\nhandling all reloaders of %+F:\n", to_spill));
 877
 878                 determine_spill_costs(env, si);
 879
 880                 /* determine possibility of rematerialisations */
 881                 if(be_do_remats) {
 882                         /* calculate cost savings for each indivial value when it would
 883                            be rematted instead of reloaded */
 884                         for (rld = si->reloaders; rld != NULL; rld = rld->next) {
 885                                 double   freq;
 886                                 int      remat_cost;
 887                                 int      remat_cost_delta;
 888                                 ir_node *block;
 889                                 ir_node *reloader = rld->reloader;
 890
 891                                 if(rld->rematted_node != NULL) {
 892                                         DBG((dbg, LEVEL_2, "\tforced remat %+F before %+F\n",
 893                                              rld->rematted_node, reloader));
 894                                         continue;
 895                                 }
 896                                 if(rld->remat_cost_delta >= REMAT_COST_INFINITE) {
 897                                         DBG((dbg, LEVEL_2, "\treload before %+F is forbidden\n",
 898                                              reloader));
 899                                         all_remat_costs = REMAT_COST_INFINITE;
 900                                         continue;
 901                                 }
 902
 903                                 remat_cost  = check_remat_conditions_costs(env, to_spill,
 904                                                                            reloader, 0);
 905                                 if(remat_cost >= REMAT_COST_INFINITE) {
 906                                         DBG((dbg, LEVEL_2, "\tremat before %+F not possible\n",
 907                                              reloader));
 908                                         rld->remat_cost_delta = REMAT_COST_INFINITE;
 909                                         all_remat_costs       = REMAT_COST_INFINITE;
 910                                         continue;
 911                                 }
 912
 913                                 remat_cost_delta      = remat_cost - env->reload_cost;
 914                                 rld->remat_cost_delta = remat_cost_delta;
 915                                 block                 = is_Block(reloader) ? reloader : get_nodes_block(reloader);
 916                                 freq                  = get_block_execfreq(exec_freq, block);
 917                                 all_remat_costs      += remat_cost_delta * freq;
 918                                 DBG((dbg, LEVEL_2, "\tremat costs delta before %+F: "
 919                                      "%d (rel %f)\n", reloader, remat_cost_delta,
 920                                      remat_cost_delta * freq));
 921                         }
 922                         if(all_remat_costs < REMAT_COST_INFINITE) {
 923                                 /* we don't need the costs for the spill if we can remat
 924                                    all reloaders */
 925                                 all_remat_costs -= si->spill_costs;
 926
 927                                 DBG((dbg, LEVEL_2, "\tspill costs %d (rel %f)\n",
 928                                      env->spill_cost, si->spill_costs));
 929                         }
 930
 931                         if(all_remat_costs < 0) {
 932                                 DBG((dbg, LEVEL_1, "\nforcing remats of all reloaders (%f)\n",
 933                                      all_remat_costs));
 934                                 force_remat = 1;
 935                         }
 936                 }
 937
 938                 /* go through all reloads for this spill */
 939                 for (rld = si->reloaders; rld != NULL; rld = rld->next) {
 940                         ir_node *copy; /* a reload is a "copy" of the original value */
 941
 942                         if (rld->rematted_node != NULL) {
 943                                 copy = rld->rematted_node;
 944                                 sched_add_before(rld->reloader, copy);
 945                         } else if (be_do_remats &&
 946                                         (force_remat || rld->remat_cost_delta < 0)) {
 947                                 copy = do_remat(env, to_spill, rld->reloader);
 948                         } else {
 949                                 /* make sure we have a spill */
 950                                 spill_node(env, si);
 951
 952                                 /* create a reload, use the first spill for now SSA
 953                                  * reconstruction for memory comes below */
 954                                 assert(si->spills != NULL);
 955                                 copy = be_reload(arch_env, si->reload_cls, rld->reloader, mode,
 956                                                  si->spills->spill);
 957 #ifdef FIRM_STATISTICS
 958                                 env->reload_count++;
 959 #endif
 960                         }
 961
 962                         DBG((dbg, LEVEL_1, " %+F of %+F before %+F\n",
 963                              copy, to_spill, rld->reloader));
 964                         ARR_APP1(ir_node*, copies, copy);
 965                 }
 966
 967                 /* if we had any reloads or remats, then we need to reconstruct the
 968                  * SSA form for the spilled value */
 969                 if (ARR_LEN(copies) > 0) {
 970                         be_ssa_construction_env_t senv;
 971                         /* be_lv_t *lv = be_get_birg_liveness(env->birg); */
 972
 973                         be_ssa_construction_init(&senv, env->birg);
 974                         be_ssa_construction_add_copy(&senv, to_spill);
 975                         be_ssa_construction_add_copies(&senv, copies, ARR_LEN(copies));
 976                         be_ssa_construction_fix_users(&senv, to_spill);
 977
 978 #if 0
 979                         /* no need to enable this as long as we invalidate liveness
 980                            after this function... */
 981                         be_ssa_construction_update_liveness_phis(&senv);
 982                         be_liveness_update(to_spill);
 983                         len = ARR_LEN(copies);
 984                         for(i = 0; i < len; ++i) {
 985                                 be_liveness_update(lv, copies[i]);
 986                         }
 987 #endif
 988                         be_ssa_construction_destroy(&senv);
 989                 }
 990                 /* need to reconstruct SSA form if we had multiple spills */
 991                 if (si->spills != NULL && si->spills->next != NULL) {
 992                         spill_t *spill;
 993                         int      spill_count = 0;
 994
 995                         be_ssa_construction_env_t senv;
 996
 997                         be_ssa_construction_init(&senv, env->birg);
 998                         spill = si->spills;
 999                         for( ; spill != NULL; spill = spill->next) {
1000                                 /* maybe we rematerialized the value and need no spill */
1001                                 if(spill->spill == NULL)
1002                                         continue;
1003                                 be_ssa_construction_add_copy(&senv, spill->spill);
1004                                 spill_count++;
1005                         }
1006                         if(spill_count > 1) {
1007                                 /* all reloads are attached to the first spill, fix them now */
1008                                 be_ssa_construction_fix_users(&senv, si->spills->spill);
1009                         }
1010
1011                         be_ssa_construction_destroy(&senv);
1012                 }
1013
1014                 DEL_ARR_F(copies);
1015                 si->reloaders = NULL;
1016         }
1017
1018         stat_ev_dbl("spill_spills", env->spill_count);
1019         stat_ev_dbl("spill_reloads", env->reload_count);
1020         stat_ev_dbl("spill_remats", env->remat_count);
1021         stat_ev_dbl("spill_spilled_phis", env->spilled_phi_count);
1022
1023         /* Matze: In theory be_ssa_construction should take care of the liveness...
1024          * try to disable this again in the future */
1025         be_liveness_invalidate(env->birg->lv);
1026
1027         be_remove_dead_nodes_from_schedule(env->birg);
1028 }
1029
1030 void be_init_spill(void)
1031 {
1032         FIRM_DBG_REGISTER(dbg, "firm.be.spill");
1033 }
1034
1035 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_spill);