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         unsigned          new_nodes_idx;  /**< all old nodes idx is smaller than
 111                                                this */
 112
 113 #ifdef FIRM_STATISTICS
 114         unsigned          spill_count;
 115         unsigned          reload_count;
 116         unsigned          remat_count;
 117         unsigned          spilled_phi_count;
 118 #endif
 119 };
 120
 121 /**
 122  * Compare two spill infos.
 123  */
 124 static int cmp_spillinfo(const void *x, const void *y, size_t size)
 125 {
 126         const spill_info_t *xx = x;
 127         const spill_info_t *yy = y;
 128         (void) size;
 129
 130         return xx->to_spill != yy->to_spill;
 131 }
 132
 133 /**
 134  * Returns spill info for a specific value (the value that is to be spilled)
 135  */
 136 static spill_info_t *get_spillinfo(const spill_env_t *env, ir_node *value)
 137 {
 138         spill_info_t info, *res;
 139         int hash = nodeset_hash(value);
 140
 141         info.to_spill = value;
 142         res = set_find(env->spills, &info, sizeof(info), hash);
 143
 144         if (res == NULL) {
 145                 info.reloaders   = NULL;
 146                 info.spills      = NULL;
 147                 info.spill_costs = -1;
 148                 info.reload_cls  = NULL;
 149                 res = set_insert(env->spills, &info, sizeof(info), hash);
 150         }
 151
 152         return res;
 153 }
 154
 155 spill_env_t *be_new_spill_env(be_irg_t *birg)
 156 {
 157         const arch_env_t *arch_env = birg->main_env->arch_env;
 158
 159         spill_env_t *env        = xmalloc(sizeof(env[0]));
 160         env->spills                     = new_set(cmp_spillinfo, 1024);
 161         env->irg            = be_get_birg_irg(birg);
 162         env->birg           = birg;
 163         env->arch_env       = arch_env;
 164         ir_nodeset_init(&env->mem_phis);
 165         env->spill_cost     = arch_env->isa->spill_cost;
 166         env->reload_cost    = arch_env->isa->reload_cost;
 167         env->exec_freq      = be_get_birg_exec_freq(birg);
 168         obstack_init(&env->obst);
 169
 170 #ifdef FIRM_STATISTICS
 171         env->spill_count       = 0;
 172         env->reload_count      = 0;
 173         env->remat_count       = 0;
 174         env->spilled_phi_count = 0;
 175 #endif
 176
 177         return env;
 178 }
 179
 180 void be_delete_spill_env(spill_env_t *env)
 181 {
 182         del_set(env->spills);
 183         ir_nodeset_destroy(&env->mem_phis);
 184         obstack_free(&env->obst, NULL);
 185         free(env);
 186 }
 187
 188 /*
 189  *  ____  _                  ____      _                 _
 190  * |  _ \| | __ _  ___ ___  |  _ \ ___| | ___   __ _  __| |___
 191  * | |_) | |/ _` |/ __/ _ \ | |_) / _ \ |/ _ \ / _` |/ _` / __|
 192  * |  __/| | (_| | (_|  __/ |  _ <  __/ | (_) | (_| | (_| \__ \
 193  * |_|   |_|\__,_|\___\___| |_| \_\___|_|\___/ \__,_|\__,_|___/
 194  *
 195  */
 196
 197 void be_add_spill(spill_env_t *env, ir_node *to_spill, ir_node *before)
 198 {
 199         spill_info_t *spill_info = get_spillinfo(env, to_spill);
 200         spill_t      *spill;
 201         spill_t      *s;
 202         spill_t      *last;
 203
 204         DB((dbg, LEVEL_1, "Add spill of %+F before %+F\n", to_spill, before));
 205
 206         /* spills that are dominated by others are not needed */
 207         last = NULL;
 208         s    = spill_info->spills;
 209         for( ; s != NULL; s = s->next) {
 210                 /* no need to add this spill if it is dominated by another */
 211                 if(value_dominates(s->before, before)) {
 212                         DB((dbg, LEVEL_1, "...dominated by %+F, not added\n", s->before));
 213                         return;
 214                 }
 215                 /* remove spills that we dominate */
 216                 if(value_dominates(before, s->before)) {
 217                         DB((dbg, LEVEL_1, "...remove old spill at %+F\n", s->before));
 218                         if(last != NULL) {
 219                                 last->next         = s->next;
 220                         } else {
 221                                 spill_info->spills = s->next;
 222                         }
 223                 } else {
 224                         last = s;
 225                 }
 226         }
 227
 228         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 229         spill->before = before;
 230         spill->next   = spill_info->spills;
 231         spill->spill  = NULL;
 232
 233         spill_info->spills = spill;
 234 }
 235
 236 void be_add_remat(spill_env_t *env, ir_node *to_spill, ir_node *before,
 237                   ir_node *rematted_node)
 238 {
 239         spill_info_t *spill_info;
 240         reloader_t *reloader;
 241
 242         spill_info = get_spillinfo(env, to_spill);
 243
 244         /* add the remat information */
 245         reloader                   = obstack_alloc(&env->obst, sizeof(reloader[0]));
 246         reloader->next             = spill_info->reloaders;
 247         reloader->reloader         = before;
 248         reloader->rematted_node    = rematted_node;
 249         reloader->remat_cost_delta = 0; /* We will never have a cost win over a
 250                                            reload since we're not even allowed to
 251                                            create a reload */
 252
 253         spill_info->reloaders  = reloader;
 254
 255         DBG((dbg, LEVEL_1, "creating spillinfo for %+F, will be rematerialized before %+F\n",
 256                 to_spill, before));
 257 }
 258
 259 void be_add_reload2(spill_env_t *env, ir_node *to_spill, ir_node *before,
 260                 ir_node *can_spill_after, const arch_register_class_t *reload_cls,
 261                 int allow_remat)
 262 {
 263         spill_info_t *info;
 264         reloader_t *rel;
 265
 266         info = get_spillinfo(env, to_spill);
 267
 268         if (is_Phi(to_spill)) {
 269                 int i, arity;
 270
 271                 /* create spillinfos for the phi arguments */
 272                 for (i = 0, arity = get_irn_arity(to_spill); i < arity; ++i) {
 273                         ir_node *arg = get_irn_n(to_spill, i);
 274                         get_spillinfo(env, arg);
 275                 }
 276         }
 277
 278         assert(!is_Proj(before) && !be_is_Keep(before));
 279
 280         /* put reload into list */
 281         rel                   = obstack_alloc(&env->obst, sizeof(rel[0]));
 282         rel->next             = info->reloaders;
 283         rel->reloader         = before;
 284         rel->rematted_node    = NULL;
 285         rel->can_spill_after  = can_spill_after;
 286         rel->remat_cost_delta = allow_remat ? 0 : REMAT_COST_INFINITE;
 287
 288         info->reloaders  = rel;
 289         assert(info->reload_cls == NULL || info->reload_cls == reload_cls);
 290         info->reload_cls = reload_cls;
 291
 292         DBG((dbg, LEVEL_1, "creating spillinfo for %+F, will be reloaded before %+F, may%s be rematerialized\n",
 293                 to_spill, before, allow_remat ? "" : " not"));
 294 }
 295
 296 void be_add_reload(spill_env_t *senv, ir_node *to_spill, ir_node *before,
 297                    const arch_register_class_t *reload_cls, int allow_remat)
 298 {
 299         be_add_reload2(senv, to_spill, before, to_spill, reload_cls, allow_remat);
 300
 301 }
 302
 303 ir_node *be_get_end_of_block_insertion_point(const ir_node *block)
 304 {
 305         ir_node *last = sched_last(block);
 306
 307         /* we might have keeps behind the jump... */
 308         while(be_is_Keep(last)) {
 309                 last = sched_prev(last);
 310                 assert(!sched_is_end(last));
 311         }
 312
 313         assert(is_cfop(last));
 314
 315         /* add the reload before the (cond-)jump */
 316         return last;
 317 }
 318
 319 /**
 320  * Returns the point at which you can insert a node that should be executed
 321  * before block @p block when coming from pred @p pos.
 322  */
 323 static ir_node *get_block_insertion_point(ir_node *block, int pos)
 324 {
 325         ir_node *predblock;
 326
 327         /* simply add the reload to the beginning of the block if we only have 1
 328          * predecessor. We don't need to check for phis as there can't be any in a
 329          * block with only 1 pred. */
 330         if(get_Block_n_cfgpreds(block) == 1) {
 331                 assert(!is_Phi(sched_first(block)));
 332                 return sched_first(block);
 333         }
 334
 335         /* We have to reload the value in pred-block */
 336         predblock = get_Block_cfgpred_block(block, pos);
 337         return be_get_end_of_block_insertion_point(predblock);
 338 }
 339
 340 void be_add_reload_at_end(spill_env_t *env, ir_node *to_spill,
 341                           const ir_node *block,
 342                           const arch_register_class_t *reload_cls,
 343                           int allow_remat)
 344 {
 345         ir_node *before = be_get_end_of_block_insertion_point(block);
 346         be_add_reload(env, to_spill, before, reload_cls, allow_remat);
 347 }
 348
 349 void be_add_reload_on_edge(spill_env_t *env, ir_node *to_spill, ir_node *block,
 350                            int pos,     const arch_register_class_t *reload_cls,
 351                            int allow_remat)
 352 {
 353         ir_node *before = get_block_insertion_point(block, pos);
 354         be_add_reload(env, to_spill, before, reload_cls, allow_remat);
 355 }
 356
 357 void be_spill_phi(spill_env_t *env, ir_node *node)
 358 {
 359         ir_node *block;
 360         spill_info_t* spill;
 361         int i, arity;
 362
 363         assert(is_Phi(node));
 364
 365         ir_nodeset_insert(&env->mem_phis, node);
 366
 367         /* create spills for the phi arguments */
 368         block = get_nodes_block(node);
 369         spill = get_spillinfo(env, node);
 370         for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
 371                 ir_node *arg        = get_irn_n(node, i);
 372                 ir_node *pred_block = get_Block_cfgpred_block(block, i);
 373                 ir_node *insert     = be_get_end_of_block_insertion_point(pred_block);
 374                 //get_spillinfo(env, arg);
 375                 be_add_spill(env, arg, insert);
 376         }
 377 }
 378
 379 /*
 380  *   ____                _         ____        _ _ _
 381  *  / ___|_ __ ___  __ _| |_ ___  / ___| _ __ (_) | |___
 382  * | |   | '__/ _ \/ _` | __/ _ \ \___ \| '_ \| | | / __|
 383  * | |___| | |  __/ (_| | ||  __/  ___) | |_) | | | \__ \
 384  *  \____|_|  \___|\__,_|\__\___| |____/| .__/|_|_|_|___/
 385  *                                      |_|
 386  */
 387
 388 static ir_node *skip_keeps_phis(ir_node *node)
 389 {
 390         node = sched_next(node);
 391         while(is_Phi(node) || be_is_Keep(node)) {
 392                 node = sched_next(node);
 393         }
 394         return node;
 395 }
 396
 397 static void determine_spill_costs(spill_env_t *env, spill_info_t *spillinfo);
 398
 399 /**
 400  * Creates a spill.
 401  *
 402  * @param senv      the spill environment
 403  * @param irn       the node that should be spilled
 404  * @param ctx_irn   an user of the spilled node
 405  *
 406  * @return a be_Spill node
 407  */
 408 static void spill_irn(spill_env_t *env, spill_info_t *spillinfo)
 409 {
 410         ir_node *to_spill = spillinfo->to_spill;
 411         spill_t *spill;
 412
 413         /* determine_spill_costs must have been run before */
 414         assert(spillinfo->spill_costs >= 0);
 415
 416         /* some backends have virtual noreg/unknown nodes that are not scheduled
 417          * and simply always available. */
 418         if(!sched_is_scheduled(to_spill)) {
 419                 /* override spillinfos or create a new one */
 420                 spillinfo->spills->spill = new_NoMem();
 421                 DB((dbg, LEVEL_1, "don't spill %+F use NoMem\n", to_spill));
 422                 return;
 423         }
 424
 425         DBG((dbg, LEVEL_1, "spilling %+F ... ", to_spill));
 426         spill = spillinfo->spills;
 427         for( ; spill != NULL; spill = spill->next) {
 428                 ir_node *block  = get_block(spill->before);
 429                 ir_node *before = spill->before;
 430
 431                 /* place all spills before the reloads (as we can't guarantee the
 432                  * same order as the be_add_spill and be_add_reload calls */
 433                 while(get_irn_idx(sched_prev(before)) > env->new_nodes_idx) {
 434                         before = sched_prev(before);
 435                 }
 436
 437                 spill->spill    = be_spill(env->arch_env, block, to_spill);
 438                 sched_add_before(before, spill->spill);
 439                 DB((dbg, LEVEL_1, "\t%+F before %+F,", spill->spill, before));
 440 #ifdef FIRM_STATISTICS
 441                 env->spill_count++;
 442 #endif
 443         }
 444         DBG((dbg, LEVEL_1, "\n"));
 445 }
 446
 447 static void spill_node(spill_env_t *env, spill_info_t *spillinfo);
 448
 449 /**
 450  * If the first usage of a Phi result would be out of memory
 451  * there is no sense in allocating a register for it.
 452  * Thus we spill it and all its operands to the same spill slot.
 453  * Therefore the phi/dataB becomes a phi/Memory
 454  *
 455  * @param senv      the spill environment
 456  * @param phi       the Phi node that should be spilled
 457  * @param ctx_irn   an user of the spilled node
 458  */
 459 static void spill_phi(spill_env_t *env, spill_info_t *spillinfo)
 460 {
 461         ir_graph *irg   = env->irg;
 462         ir_node  *phi   = spillinfo->to_spill;
 463         ir_node  *block = get_nodes_block(phi);
 464         ir_node  *unknown;
 465         ir_node **ins;
 466         spill_t  *spill;
 467         int       i;
 468         int       arity;
 469
 470         assert(is_Phi(phi));
 471         assert(!get_opt_cse());
 472         DBG((dbg, LEVEL_1, "spilling Phi %+F:\n", phi));
 473
 474         /* build a new PhiM */
 475         arity   = get_irn_arity(phi);
 476         ins     = alloca(sizeof(ir_node*) * arity);
 477         unknown = new_r_Unknown(irg, mode_M);
 478         for(i = 0; i < arity; ++i) {
 479                 ins[i] = unknown;
 480         }
 481
 482         /* override or replace spills list... */
 483         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 484         spill->before = skip_keeps_phis(phi);
 485         spill->spill  = new_r_Phi(irg, block, arity, ins, mode_M);
 486         spill->next   = NULL;
 487
 488         spillinfo->spills = spill;
 489 #ifdef FIRM_STATISTICS
 490         env->spilled_phi_count++;
 491 #endif
 492
 493         for(i = 0; i < arity; ++i) {
 494                 ir_node      *arg      = get_irn_n(phi, i);
 495                 spill_info_t *arg_info = get_spillinfo(env, arg);
 496
 497                 determine_spill_costs(env, arg_info);
 498                 spill_node(env, arg_info);
 499
 500                 set_irn_n(spill->spill, i, arg_info->spills->spill);
 501         }
 502         DBG((dbg, LEVEL_1, "... done spilling Phi %+F, created PhiM %+F\n", phi,
 503              spill->spill));
 504 }
 505
 506 /**
 507  * Spill a node.
 508  *
 509  * @param senv      the spill environment
 510  * @param to_spill  the node that should be spilled
 511  */
 512 static void spill_node(spill_env_t *env, spill_info_t *spillinfo)
 513 {
 514         ir_node *to_spill;
 515
 516         /* node is already spilled */
 517         if(spillinfo->spills != NULL && spillinfo->spills->spill != NULL)
 518                 return;
 519
 520         to_spill = spillinfo->to_spill;
 521
 522         if (is_Phi(to_spill) && ir_nodeset_contains(&env->mem_phis, to_spill)) {
 523                 spill_phi(env, spillinfo);
 524         } else {
 525                 spill_irn(env, spillinfo);
 526         }
 527 }
 528
 529 /*
 530  *
 531  *  ____                      _            _       _ _
 532  * |  _ \ ___ _ __ ___   __ _| |_ ___ _ __(_) __ _| (_)_______
 533  * | |_) / _ \ '_ ` _ \ / _` | __/ _ \ '__| |/ _` | | |_  / _ \
 534  * |  _ <  __/ | | | | | (_| | ||  __/ |  | | (_| | | |/ /  __/
 535  * |_| \_\___|_| |_| |_|\__,_|\__\___|_|  |_|\__,_|_|_/___\___|
 536  *
 537  */
 538
 539 /**
 540  * Tests whether value @p arg is available before node @p reloader
 541  * @returns 1 if value is available, 0 otherwise
 542  */
 543 static int is_value_available(spill_env_t *env, const ir_node *arg,
 544                               const ir_node *reloader)
 545 {
 546         if(is_Unknown(arg) || arg == new_NoMem())
 547                 return 1;
 548
 549         if(be_is_Spill(arg))
 550                 return 1;
 551
 552         if(arg == get_irg_frame(env->irg))
 553                 return 1;
 554
 555         /* hack for now (happens when command should be inserted at end of block) */
 556         if(is_Block(reloader)) {
 557                 return 0;
 558         }
 559
 560         /*
 561          * Ignore registers are always available
 562          */
 563         if(arch_irn_is(env->arch_env, arg, ignore)) {
 564                 return 1;
 565         }
 566
 567         /* the following test does not work while spilling,
 568          * because the liveness info is not adapted yet to the effects of the
 569          * additional spills/reloads.
 570          */
 571 #if 0
 572         /* we want to remat before the insn reloader
 573          * thus an arguments is alive if
 574          *   - it interferes with the reloaders result
 575          *   - or it is (last-) used by reloader itself
 576          */
 577         if (values_interfere(env->birg->lv, reloader, arg)) {
 578                 return 1;
 579         }
 580
 581         arity = get_irn_arity(reloader);
 582         for (i = 0; i < arity; ++i) {
 583                 ir_node *rel_arg = get_irn_n(reloader, i);
 584                 if (rel_arg == arg)
 585                         return 1;
 586         }
 587 #endif
 588
 589         return 0;
 590 }
 591
 592 /**
 593  * Checks whether the node can principally be rematerialized
 594  */
 595 static int is_remat_node(spill_env_t *env, const ir_node *node)
 596 {
 597         const arch_env_t *arch_env = env->arch_env;
 598
 599         assert(!be_is_Spill(node));
 600
 601         if(arch_irn_is(arch_env, node, rematerializable))
 602                 return 1;
 603
 604         return 0;
 605 }
 606
 607 /**
 608  * Check if a node is rematerializable. This tests for the following conditions:
 609  *
 610  * - The node itself is rematerializable
 611  * - All arguments of the node are available or also rematerialisable
 612  * - The costs for the rematerialisation operation is less or equal a limit
 613  *
 614  * Returns the costs needed for rematerialisation or something
 615  * >= REMAT_COST_INFINITE if remat is not possible.
 616  */
 617 static int check_remat_conditions_costs(spill_env_t *env,
 618                 const ir_node *spilled, const ir_node *reloader, int parentcosts)
 619 {
 620         int i, arity;
 621         int argremats;
 622         int costs = 0;
 623
 624         if(!is_remat_node(env, spilled))
 625                 return REMAT_COST_INFINITE;
 626
 627         if(be_is_Reload(spilled)) {
 628                 costs += 2;
 629         } else {
 630                 costs += arch_get_op_estimated_cost(env->arch_env, spilled);
 631         }
 632         if(parentcosts + costs >= env->reload_cost + env->spill_cost) {
 633                 return REMAT_COST_INFINITE;
 634         }
 635         if(arch_irn_is(env->arch_env, spilled, modify_flags)) {
 636                 return REMAT_COST_INFINITE;
 637         }
 638
 639         argremats = 0;
 640         for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
 641                 ir_node *arg = get_irn_n(spilled, i);
 642
 643                 if(is_value_available(env, arg, reloader))
 644                         continue;
 645
 646                 /* we have to rematerialize the argument as well */
 647                 if(argremats >= 1) {
 648                         /* we only support rematerializing 1 argument at the moment,
 649                          * so that we don't have to care about register pressure
 650                          */
 651                         return REMAT_COST_INFINITE;
 652                 }
 653                 argremats++;
 654
 655                 costs += check_remat_conditions_costs(env, arg, reloader,
 656                                                       parentcosts + costs);
 657                 if(parentcosts + costs >= env->reload_cost + env->spill_cost)
 658                         return REMAT_COST_INFINITE;
 659         }
 660
 661         return costs;
 662 }
 663
 664 /**
 665  * Re-materialize a node.
 666  *
 667  * @param senv      the spill environment
 668  * @param spilled   the node that was spilled
 669  * @param reloader  a irn that requires a reload
 670  */
 671 static ir_node *do_remat(spill_env_t *env, ir_node *spilled, ir_node *reloader)
 672 {
 673         int i, arity;
 674         ir_node *res;
 675         ir_node *bl;
 676         ir_node **ins;
 677
 678         if(is_Block(reloader)) {
 679                 bl = reloader;
 680         } else {
 681                 bl = get_nodes_block(reloader);
 682         }
 683
 684         ins = alloca(get_irn_arity(spilled) * sizeof(ins[0]));
 685         for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
 686                 ir_node *arg = get_irn_n(spilled, i);
 687
 688                 if(is_value_available(env, arg, reloader)) {
 689                         ins[i] = arg;
 690                 } else {
 691                         ins[i] = do_remat(env, arg, reloader);
 692 #ifdef FIRM_STATISTICS
 693                         /* don't count the recursive call as remat */
 694                         env->remat_count--;
 695 #endif
 696                 }
 697         }
 698
 699         /* create a copy of the node */
 700         res = new_ir_node(get_irn_dbg_info(spilled), env->irg, bl,
 701                           get_irn_op(spilled), get_irn_mode(spilled),
 702                           get_irn_arity(spilled), ins);
 703         copy_node_attr(spilled, res);
 704         new_backedge_info(res);
 705
 706         DBG((dbg, LEVEL_1, "Insert remat %+F of %+F before reloader %+F\n", res, spilled, reloader));
 707
 708         if (! is_Proj(res)) {
 709                 /* insert in schedule */
 710                 sched_reset(res);
 711                 sched_add_before(reloader, res);
 712 #ifdef FIRM_STATISTICS
 713                 env->remat_count++;
 714 #endif
 715         }
 716
 717         return res;
 718 }
 719
 720 double be_get_spill_costs(spill_env_t *env, ir_node *to_spill, ir_node *before)
 721 {
 722         ir_node *block = get_nodes_block(before);
 723         double   freq  = get_block_execfreq(env->exec_freq, block);
 724         (void) to_spill;
 725
 726         return env->spill_cost * freq;
 727 }
 728
 729 double be_get_reload_costs(spill_env_t *env, ir_node *to_spill, ir_node *before)
 730 {
 731         ir_node      *block = get_nodes_block(before);
 732         double        freq  = get_block_execfreq(env->exec_freq, block);
 733
 734         if(be_do_remats) {
 735                 /* is the node rematerializable? */
 736                 int costs = check_remat_conditions_costs(env, to_spill, before, 0);
 737                 if(costs < env->reload_cost)
 738                         return costs * freq;
 739         }
 740
 741         return env->reload_cost * freq;
 742 }
 743
 744 int be_is_rematerializable(spill_env_t *env, const ir_node *to_remat,
 745                            const ir_node *before)
 746 {
 747         return check_remat_conditions_costs(env, to_remat, before, 0) < REMAT_COST_INFINITE;
 748 }
 749
 750 double be_get_reload_costs_on_edge(spill_env_t *env, ir_node *to_spill,
 751                                    ir_node *block, int pos)
 752 {
 753         ir_node *before = get_block_insertion_point(block, pos);
 754         return be_get_reload_costs(env, to_spill, before);
 755 }
 756
 757 /*
 758  *  ___                     _     ____      _                 _
 759  * |_ _|_ __  ___  ___ _ __| |_  |  _ \ ___| | ___   __ _  __| |___
 760  *  | || '_ \/ __|/ _ \ '__| __| | |_) / _ \ |/ _ \ / _` |/ _` / __|
 761  *  | || | | \__ \  __/ |  | |_  |  _ <  __/ | (_) | (_| | (_| \__ \
 762  * |___|_| |_|___/\___|_|   \__| |_| \_\___|_|\___/ \__,_|\__,_|___/
 763  *
 764  */
 765
 766 /**
 767  * analyzes how to best spill a node and determine costs for that
 768  */
 769 static void determine_spill_costs(spill_env_t *env, spill_info_t *spillinfo)
 770 {
 771         ir_node *to_spill = spillinfo->to_spill;
 772         ir_node *spill_block;
 773         spill_t *spill;
 774         double   spill_execfreq;
 775
 776         /* already calculated? */
 777         if(spillinfo->spill_costs >= 0)
 778                 return;
 779
 780         assert(! arch_irn_is(env->arch_env, to_spill, dont_spill));
 781         assert(!be_is_Reload(to_spill));
 782
 783         /* some backends have virtual noreg/unknown nodes that are not scheduled
 784          * and simply always available.
 785          * TODO: this is kinda hairy, the NoMem is correct for an Unknown as Phi
 786          * predecessor (of a PhiM) but this test might match other things too...
 787          */
 788         if(!sched_is_scheduled(to_spill)) {
 789                 /* override spillinfos or create a new one */
 790                 spill_t *spill = obstack_alloc(&env->obst, sizeof(spill[0]));
 791                 spill->before  = NULL;
 792                 spill->next    = NULL;
 793                 spill->spill   = new_NoMem();
 794
 795                 spillinfo->spills      = spill;
 796                 spillinfo->spill_costs = 0;
 797
 798                 DB((dbg, LEVEL_1, "don't spill %+F use NoMem\n", to_spill));
 799                 return;
 800         }
 801
 802         spill_block    = get_nodes_block(to_spill);
 803         spill_execfreq = get_block_execfreq(env->exec_freq, spill_block);
 804
 805         if (is_Phi(to_spill) && ir_nodeset_contains(&env->mem_phis, to_spill)) {
 806                 /* TODO calculate correct costs...
 807                  * (though we can't remat this node anyway so no big problem) */
 808                 spillinfo->spill_costs = env->spill_cost * spill_execfreq;
 809                 return;
 810         }
 811
 812         if(spillinfo->spills != NULL) {
 813                 spill_t *s;
 814                 double   spills_execfreq;
 815
 816                 /* calculate sum of executaion frequencies of individual spills */
 817                 spills_execfreq = 0;
 818                 s               = spillinfo->spills;
 819                 for( ; s != NULL; s = s->next) {
 820                         ir_node *spill_block = s->before;
 821                         double   freq;
 822
 823                         if(!is_Block(spill_block)) {
 824                                 spill_block = get_nodes_block(spill_block);
 825                         }
 826                         freq = get_block_execfreq(env->exec_freq, spill_block);
 827
 828                         spills_execfreq += freq;
 829                 }
 830
 831                 DB((dbg, LEVEL_1, "%+F: latespillcosts %f after def: %f\n", to_spill,
 832                     spills_execfreq * env->spill_cost,
 833                     spill_execfreq * env->spill_cost));
 834
 835                 /* multi-/latespill is advantageous -> return*/
 836                 if(spills_execfreq < spill_execfreq) {
 837                         DB((dbg, LEVEL_1, "use latespills for %+F\n", to_spill));
 838                         spillinfo->spill_costs = spills_execfreq * env->spill_cost;
 839                         return;
 840                 }
 841         }
 842
 843         /* override spillinfos or create a new one */
 844         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 845         spill->before = skip_keeps_phis(to_spill);
 846         spill->next   = NULL;
 847         spill->spill  = NULL;
 848
 849         spillinfo->spills      = spill;
 850         spillinfo->spill_costs = spill_execfreq * env->spill_cost;
 851         DB((dbg, LEVEL_1, "spill %+F after definition\n", to_spill));
 852 }
 853
 854 void be_insert_spills_reloads(spill_env_t *env)
 855 {
 856         ir_graph              *irg       = env->irg;
 857         const arch_env_t      *arch_env  = env->arch_env;
 858         const ir_exec_freq    *exec_freq = env->exec_freq;
 859         spill_info_t          *si;
 860         ir_nodeset_iterator_t  iter;
 861         ir_node               *node;
 862
 863         env->new_nodes_idx = get_irg_last_idx(irg);
 864
 865         /* create all phi-ms first, this is needed so, that phis, hanging on
 866            spilled phis work correctly */
 867         foreach_ir_nodeset(&env->mem_phis, node, iter) {
 868                 spill_info_t *info = get_spillinfo(env, node);
 869                 spill_node(env, info);
 870         }
 871
 872         /* process each spilled node */
 873         for (si = set_first(env->spills); si; si = set_next(env->spills)) {
 874                 reloader_t *rld;
 875                 ir_node  *to_spill        = si->to_spill;
 876                 ir_mode  *mode            = get_irn_mode(to_spill);
 877                 ir_node **copies          = NEW_ARR_F(ir_node*, 0);
 878                 double    all_remat_costs = 0; /** costs when we would remat all nodes */
 879                 int       force_remat     = 0;
 880
 881                 DBG((dbg, LEVEL_1, "\nhandling all reloaders of %+F:\n", to_spill));
 882
 883                 determine_spill_costs(env, si);
 884
 885                 /* determine possibility of rematerialisations */
 886                 if(be_do_remats) {
 887                         /* calculate cost savings for each indivial value when it would
 888                            be rematted instead of reloaded */
 889                         for (rld = si->reloaders; rld != NULL; rld = rld->next) {
 890                                 double   freq;
 891                                 int      remat_cost;
 892                                 int      remat_cost_delta;
 893                                 ir_node *block;
 894                                 ir_node *reloader = rld->reloader;
 895
 896                                 if(rld->rematted_node != NULL) {
 897                                         DBG((dbg, LEVEL_2, "\tforced remat %+F before %+F\n",
 898                                              rld->rematted_node, reloader));
 899                                         continue;
 900                                 }
 901                                 if(rld->remat_cost_delta >= REMAT_COST_INFINITE) {
 902                                         DBG((dbg, LEVEL_2, "\treload before %+F is forbidden\n",
 903                                              reloader));
 904                                         all_remat_costs = REMAT_COST_INFINITE;
 905                                         continue;
 906                                 }
 907
 908                                 remat_cost  = check_remat_conditions_costs(env, to_spill,
 909                                                                            reloader, 0);
 910                                 if(remat_cost >= REMAT_COST_INFINITE) {
 911                                         DBG((dbg, LEVEL_2, "\tremat before %+F not possible\n",
 912                                              reloader));
 913                                         rld->remat_cost_delta = REMAT_COST_INFINITE;
 914                                         all_remat_costs       = REMAT_COST_INFINITE;
 915                                         continue;
 916                                 }
 917
 918                                 remat_cost_delta      = remat_cost - env->reload_cost;
 919                                 rld->remat_cost_delta = remat_cost_delta;
 920                                 block                 = is_Block(reloader) ? reloader : get_nodes_block(reloader);
 921                                 freq                  = get_block_execfreq(exec_freq, block);
 922                                 all_remat_costs      += remat_cost_delta * freq;
 923                                 DBG((dbg, LEVEL_2, "\tremat costs delta before %+F: "
 924                                      "%d (rel %f)\n", reloader, remat_cost_delta,
 925                                      remat_cost_delta * freq));
 926                         }
 927                         if(all_remat_costs < REMAT_COST_INFINITE) {
 928                                 /* we don't need the costs for the spill if we can remat
 929                                    all reloaders */
 930                                 all_remat_costs -= si->spill_costs;
 931
 932                                 DBG((dbg, LEVEL_2, "\tspill costs %d (rel %f)\n",
 933                                      env->spill_cost, si->spill_costs));
 934                         }
 935
 936                         if(all_remat_costs < 0) {
 937                                 DBG((dbg, LEVEL_1, "\nforcing remats of all reloaders (%f)\n",
 938                                      all_remat_costs));
 939                                 force_remat = 1;
 940                         }
 941                 }
 942
 943                 /* go through all reloads for this spill */
 944                 for (rld = si->reloaders; rld != NULL; rld = rld->next) {
 945                         ir_node *copy; /* a reload is a "copy" of the original value */
 946
 947                         if (rld->rematted_node != NULL) {
 948                                 copy = rld->rematted_node;
 949                                 sched_add_before(rld->reloader, copy);
 950                         } else if (be_do_remats &&
 951                                         (force_remat || rld->remat_cost_delta < 0)) {
 952                                 copy = do_remat(env, to_spill, rld->reloader);
 953                         } else {
 954                                 /* make sure we have a spill */
 955                                 spill_node(env, si);
 956
 957                                 /* create a reload, use the first spill for now SSA
 958                                  * reconstruction for memory comes below */
 959                                 assert(si->spills != NULL);
 960                                 copy = be_reload(arch_env, si->reload_cls, rld->reloader, mode,
 961                                                  si->spills->spill);
 962 #ifdef FIRM_STATISTICS
 963                                 env->reload_count++;
 964 #endif
 965                         }
 966
 967                         DBG((dbg, LEVEL_1, " %+F of %+F before %+F\n",
 968                              copy, to_spill, rld->reloader));
 969                         ARR_APP1(ir_node*, copies, copy);
 970                 }
 971
 972                 /* if we had any reloads or remats, then we need to reconstruct the
 973                  * SSA form for the spilled value */
 974                 if (ARR_LEN(copies) > 0) {
 975                         be_ssa_construction_env_t senv;
 976                         /* be_lv_t *lv = be_get_birg_liveness(env->birg); */
 977
 978                         be_ssa_construction_init(&senv, env->birg);
 979                         be_ssa_construction_add_copy(&senv, to_spill);
 980                         be_ssa_construction_add_copies(&senv, copies, ARR_LEN(copies));
 981                         be_ssa_construction_fix_users(&senv, to_spill);
 982
 983 #if 0
 984                         /* no need to enable this as long as we invalidate liveness
 985                            after this function... */
 986                         be_ssa_construction_update_liveness_phis(&senv);
 987                         be_liveness_update(to_spill);
 988                         len = ARR_LEN(copies);
 989                         for(i = 0; i < len; ++i) {
 990                                 be_liveness_update(lv, copies[i]);
 991                         }
 992 #endif
 993                         be_ssa_construction_destroy(&senv);
 994                 }
 995                 /* need to reconstruct SSA form if we had multiple spills */
 996                 if (si->spills != NULL && si->spills->next != NULL) {
 997                         spill_t *spill;
 998                         int      spill_count = 0;
 999
1000                         be_ssa_construction_env_t senv;
1001
1002                         be_ssa_construction_init(&senv, env->birg);
1003                         spill = si->spills;
1004                         for( ; spill != NULL; spill = spill->next) {
1005                                 /* maybe we rematerialized the value and need no spill */
1006                                 if(spill->spill == NULL)
1007                                         continue;
1008                                 be_ssa_construction_add_copy(&senv, spill->spill);
1009                                 spill_count++;
1010                         }
1011                         if(spill_count > 1) {
1012                                 /* all reloads are attached to the first spill, fix them now */
1013                                 be_ssa_construction_fix_users(&senv, si->spills->spill);
1014                         }
1015
1016                         be_ssa_construction_destroy(&senv);
1017                 }
1018
1019                 DEL_ARR_F(copies);
1020                 si->reloaders = NULL;
1021         }
1022
1023         stat_ev_dbl("spill_spills", env->spill_count);
1024         stat_ev_dbl("spill_reloads", env->reload_count);
1025         stat_ev_dbl("spill_remats", env->remat_count);
1026         stat_ev_dbl("spill_spilled_phis", env->spilled_phi_count);
1027
1028         /* Matze: In theory be_ssa_construction should take care of the liveness...
1029          * try to disable this again in the future */
1030         be_liveness_invalidate(env->birg->lv);
1031
1032         be_remove_dead_nodes_from_schedule(env->birg);
1033 }
1034
1035 void be_init_spill(void)
1036 {
1037         FIRM_DBG_REGISTER(dbg, "firm.be.spill");
1038 }
1039
1040 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_spill);