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

   1 /*
   2  * Copyright (C) 1995-2008 University of Karlsruhe.  All right reserved.
   3  *
   4  * This file is part of libFirm.
   5  *
   6  * This file may be distributed and/or modified under the terms of the
   7  * GNU General Public License version 2 as published by the Free Software
   8  * Foundation and appearing in the file LICENSE.GPL included in the
   9  * packaging of this file.
  10  *
  11  * Licensees holding valid libFirm Professional Edition licenses may use
  12  * this file in accordance with the libFirm Commercial License.
  13  * Agreement provided with the Software.
  14  *
  15  * This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
  16  * WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
  17  * PURPOSE.
  18  */
  19
  20 /**
  21  * @file
  22  * @brief       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 "bespilloptions.h"
  59 #include "bestatevent.h"
  60 #include "bessaconstr.h"
  61 #include "beirg_t.h"
  62 #include "beintlive_t.h"
  63 #include "bemodule.h"
  64
  65 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  66
  67 #define REMAT_COST_INFINITE  1000
  68
  69 typedef struct reloader_t reloader_t;
  70 struct reloader_t {
  71         reloader_t *next;
  72         ir_node    *can_spill_after;
  73         ir_node    *reloader;
  74         ir_node    *rematted_node;
  75         int         remat_cost_delta; /** costs needed for rematerialization,
  76                                            compared to placing a reload */
  77 };
  78
  79 typedef struct spill_t spill_t;
  80 struct spill_t {
  81         spill_t *next;
  82         ir_node *before;   /**< spill has to be placed before this node (or earlier) */
  83         ir_node *spill;
  84 };
  85
  86 typedef struct spill_info_t spill_info_t;
  87 struct spill_info_t {
  88         ir_node    *to_spill;  /**< the value that should get spilled */
  89         reloader_t *reloaders; /**< list of places where the value should get
  90                                     reloaded */
  91         spill_t    *spills;    /**< list of latest places where spill must be
  92                                     placed */
  93         double      spill_costs; /**< costs needed for spilling the value */
  94         const arch_register_class_t *reload_cls; /** the register class in which the
  95                                                      reload should be placed */
  96 };
  97
  98 struct spill_env_t {
  99         const arch_env_t *arch_env;
 100         ir_graph         *irg;
 101         struct obstack    obst;
 102         be_irg_t         *birg;
 103         int               spill_cost;     /**< the cost of a single spill node */
 104         int               reload_cost;    /**< the cost of a reload node */
 105         set              *spills;         /**< all spill_info_t's, which must be
 106                                                placed */
 107         ir_nodeset_t      mem_phis;       /**< set of all spilled phis. */
 108         ir_exec_freq     *exec_freq;
 109         unsigned          new_nodes_idx;  /**< all old nodes idx is smaller than
 110                                                this */
 111
 112 #ifdef FIRM_STATISTICS
 113         unsigned          spill_count;
 114         unsigned          reload_count;
 115         unsigned          remat_count;
 116         unsigned          spilled_phi_count;
 117 #endif
 118 };
 119
 120 /**
 121  * Compare two spill infos.
 122  */
 123 static int cmp_spillinfo(const void *x, const void *y, size_t size)
 124 {
 125         const spill_info_t *xx = x;
 126         const spill_info_t *yy = y;
 127         (void) size;
 128
 129         return xx->to_spill != yy->to_spill;
 130 }
 131
 132 /**
 133  * Returns spill info for a specific value (the value that is to be spilled)
 134  */
 135 static spill_info_t *get_spillinfo(const spill_env_t *env, ir_node *value)
 136 {
 137         spill_info_t info, *res;
 138         int hash = hash_irn(value);
 139
 140         info.to_spill = value;
 141         res = set_find(env->spills, &info, sizeof(info), hash);
 142
 143         if (res == NULL) {
 144                 info.reloaders   = NULL;
 145                 info.spills      = NULL;
 146                 info.spill_costs = -1;
 147                 info.reload_cls  = NULL;
 148                 res = set_insert(env->spills, &info, sizeof(info), hash);
 149         }
 150
 151         return res;
 152 }
 153
 154 spill_env_t *be_new_spill_env(be_irg_t *birg)
 155 {
 156         const arch_env_t *arch_env = birg->main_env->arch_env;
 157
 158         spill_env_t *env        = xmalloc(sizeof(env[0]));
 159         env->spills                     = new_set(cmp_spillinfo, 1024);
 160         env->irg            = be_get_birg_irg(birg);
 161         env->birg           = birg;
 162         env->arch_env       = arch_env;
 163         ir_nodeset_init(&env->mem_phis);
 164         env->spill_cost     = arch_env->isa->spill_cost;
 165         env->reload_cost    = arch_env->isa->reload_cost;
 166         env->exec_freq      = be_get_birg_exec_freq(birg);
 167         obstack_init(&env->obst);
 168
 169 #ifdef FIRM_STATISTICS
 170         env->spill_count       = 0;
 171         env->reload_count      = 0;
 172         env->remat_count       = 0;
 173         env->spilled_phi_count = 0;
 174 #endif
 175
 176         return env;
 177 }
 178
 179 void be_delete_spill_env(spill_env_t *env)
 180 {
 181         del_set(env->spills);
 182         ir_nodeset_destroy(&env->mem_phis);
 183         obstack_free(&env->obst, NULL);
 184         free(env);
 185 }
 186
 187 /*
 188  *  ____  _                  ____      _                 _
 189  * |  _ \| | __ _  ___ ___  |  _ \ ___| | ___   __ _  __| |___
 190  * | |_) | |/ _` |/ __/ _ \ | |_) / _ \ |/ _ \ / _` |/ _` / __|
 191  * |  __/| | (_| | (_|  __/ |  _ <  __/ | (_) | (_| | (_| \__ \
 192  * |_|   |_|\__,_|\___\___| |_| \_\___|_|\___/ \__,_|\__,_|___/
 193  *
 194  */
 195
 196 void be_add_spill(spill_env_t *env, ir_node *to_spill, ir_node *before)
 197 {
 198 #if 1
 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         assert(! arch_irn_is(env->arch_env, to_spill, dont_spill));
 205         DB((dbg, LEVEL_1, "Add spill of %+F before %+F\n", to_spill, before));
 206
 207         /* spills that are dominated by others are not needed */
 208         last = NULL;
 209         s    = spill_info->spills;
 210         for( ; s != NULL; s = s->next) {
 211                 /* no need to add this spill if it is dominated by another */
 212                 if(value_dominates(s->before, before)) {
 213                         DB((dbg, LEVEL_1, "...dominated by %+F, not added\n", s->before));
 214                         return;
 215                 }
 216                 /* remove spills that we dominate */
 217                 if(value_dominates(before, s->before)) {
 218                         DB((dbg, LEVEL_1, "...remove old spill at %+F\n", s->before));
 219                         if(last != NULL) {
 220                                 last->next         = s->next;
 221                         } else {
 222                                 spill_info->spills = s->next;
 223                         }
 224                 } else {
 225                         last = s;
 226                 }
 227         }
 228
 229         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 230         spill->before = before;
 231         spill->next   = spill_info->spills;
 232         spill->spill  = NULL;
 233
 234         spill_info->spills = spill;
 235 #endif
 236 }
 237
 238 void be_add_remat(spill_env_t *env, ir_node *to_spill, ir_node *before,
 239                   ir_node *rematted_node)
 240 {
 241         spill_info_t *spill_info;
 242         reloader_t *reloader;
 243
 244         spill_info = get_spillinfo(env, to_spill);
 245
 246         /* add the remat information */
 247         reloader                   = obstack_alloc(&env->obst, sizeof(reloader[0]));
 248         reloader->next             = spill_info->reloaders;
 249         reloader->reloader         = before;
 250         reloader->rematted_node    = rematted_node;
 251         reloader->remat_cost_delta = 0; /* We will never have a cost win over a
 252                                            reload since we're not even allowed to
 253                                            create a reload */
 254
 255         spill_info->reloaders  = reloader;
 256
 257         DBG((dbg, LEVEL_1, "creating spillinfo for %+F, will be rematerialized before %+F\n",
 258                 to_spill, before));
 259 }
 260
 261 void be_add_reload2(spill_env_t *env, ir_node *to_spill, ir_node *before,
 262                 ir_node *can_spill_after, const arch_register_class_t *reload_cls,
 263                 int allow_remat)
 264 {
 265         spill_info_t *info;
 266         reloader_t *rel;
 267
 268         assert(! arch_irn_is(env->arch_env, to_spill, dont_spill));
 269
 270         info = get_spillinfo(env, to_spill);
 271
 272         if (is_Phi(to_spill)) {
 273                 int i, arity;
 274
 275                 /* create spillinfos for the phi arguments */
 276                 for (i = 0, arity = get_irn_arity(to_spill); i < arity; ++i) {
 277                         ir_node *arg = get_irn_n(to_spill, i);
 278                         get_spillinfo(env, arg);
 279                 }
 280         }
 281
 282         assert(!is_Proj(before) && !be_is_Keep(before));
 283
 284         /* put reload into list */
 285         rel                   = obstack_alloc(&env->obst, sizeof(rel[0]));
 286         rel->next             = info->reloaders;
 287         rel->reloader         = before;
 288         rel->rematted_node    = NULL;
 289         rel->can_spill_after  = can_spill_after;
 290         rel->remat_cost_delta = allow_remat ? 0 : REMAT_COST_INFINITE;
 291
 292         info->reloaders  = rel;
 293         assert(info->reload_cls == NULL || info->reload_cls == reload_cls);
 294         info->reload_cls = reload_cls;
 295
 296         DBG((dbg, LEVEL_1, "creating spillinfo for %+F, will be reloaded before %+F, may%s be rematerialized\n",
 297                 to_spill, before, allow_remat ? "" : " not"));
 298 }
 299
 300 void be_add_reload(spill_env_t *senv, ir_node *to_spill, ir_node *before,
 301                    const arch_register_class_t *reload_cls, int allow_remat)
 302 {
 303         be_add_reload2(senv, to_spill, before, to_spill, reload_cls, allow_remat);
 304
 305 }
 306
 307 ir_node *be_get_end_of_block_insertion_point(const ir_node *block)
 308 {
 309         ir_node *last = sched_last(block);
 310
 311         /* we might have keeps behind the jump... */
 312         while(be_is_Keep(last)) {
 313                 last = sched_prev(last);
 314                 assert(!sched_is_end(last));
 315         }
 316
 317         assert(is_cfop(last));
 318
 319         /* add the reload before the (cond-)jump */
 320         return last;
 321 }
 322
 323 static ir_node *skip_keeps_phis(ir_node *node)
 324 {
 325         node = sched_next(node);
 326         while(is_Phi(node) || be_is_Keep(node)) {
 327                 node = sched_next(node);
 328         }
 329         return node;
 330 }
 331
 332 /**
 333  * Returns the point at which you can insert a node that should be executed
 334  * before block @p block when coming from pred @p pos.
 335  */
 336 static ir_node *get_block_insertion_point(ir_node *block, int pos)
 337 {
 338         ir_node *predblock;
 339
 340         /* simply add the reload to the beginning of the block if we only have 1
 341          * predecessor. We don't need to check for phis as there can't be any in a
 342          * block with only 1 pred. */
 343         if(get_Block_n_cfgpreds(block) == 1) {
 344                 assert(!is_Phi(sched_first(block)));
 345                 return sched_first(block);
 346         }
 347
 348         /* We have to reload the value in pred-block */
 349         predblock = get_Block_cfgpred_block(block, pos);
 350         return be_get_end_of_block_insertion_point(predblock);
 351 }
 352
 353 void be_add_reload_at_end(spill_env_t *env, ir_node *to_spill,
 354                           const ir_node *block,
 355                           const arch_register_class_t *reload_cls,
 356                           int allow_remat)
 357 {
 358         ir_node *before = be_get_end_of_block_insertion_point(block);
 359         be_add_reload(env, to_spill, before, reload_cls, allow_remat);
 360 }
 361
 362 void be_add_reload_on_edge(spill_env_t *env, ir_node *to_spill, ir_node *block,
 363                            int pos,     const arch_register_class_t *reload_cls,
 364                            int allow_remat)
 365 {
 366         ir_node *before = get_block_insertion_point(block, pos);
 367         be_add_reload(env, to_spill, before, reload_cls, allow_remat);
 368 }
 369
 370 void be_spill_phi(spill_env_t *env, ir_node *node)
 371 {
 372         ir_node *block;
 373         spill_info_t* spill;
 374         int i, arity;
 375
 376         assert(is_Phi(node));
 377
 378         ir_nodeset_insert(&env->mem_phis, node);
 379
 380         /* create spills for the phi arguments */
 381         block = get_nodes_block(node);
 382         spill = get_spillinfo(env, node);
 383         for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
 384                 ir_node *arg        = get_irn_n(node, i);
 385                 ir_node *insert;
 386                 //get_spillinfo(env, arg);
 387
 388                 /* some backends have virtual noreg/unknown nodes that are not scheduled
 389                  * and simply always available. */
 390                 if(!sched_is_scheduled(arg)) {
 391                         ir_node *pred_block = get_Block_cfgpred_block(block, i);
 392                         insert = be_get_end_of_block_insertion_point(pred_block);
 393                 } else {
 394                         insert = skip_keeps_phis(arg);
 395                 }
 396
 397                 be_add_spill(env, arg, insert);
 398         }
 399 }
 400
 401 /*
 402  *   ____                _         ____        _ _ _
 403  *  / ___|_ __ ___  __ _| |_ ___  / ___| _ __ (_) | |___
 404  * | |   | '__/ _ \/ _` | __/ _ \ \___ \| '_ \| | | / __|
 405  * | |___| | |  __/ (_| | ||  __/  ___) | |_) | | | \__ \
 406  *  \____|_|  \___|\__,_|\__\___| |____/| .__/|_|_|_|___/
 407  *                                      |_|
 408  */
 409
 410 static void determine_spill_costs(spill_env_t *env, spill_info_t *spillinfo);
 411
 412 /**
 413  * Creates a spill.
 414  *
 415  * @param senv      the spill environment
 416  * @param irn       the node that should be spilled
 417  * @param ctx_irn   an user of the spilled node
 418  *
 419  * @return a be_Spill node
 420  */
 421 static void spill_irn(spill_env_t *env, spill_info_t *spillinfo)
 422 {
 423         ir_node *to_spill = spillinfo->to_spill;
 424         spill_t *spill;
 425
 426         /* determine_spill_costs must have been run before */
 427         assert(spillinfo->spill_costs >= 0);
 428
 429         /* some backends have virtual noreg/unknown nodes that are not scheduled
 430          * and simply always available. */
 431         if(!sched_is_scheduled(to_spill)) {
 432                 /* override spillinfos or create a new one */
 433                 spillinfo->spills->spill = new_NoMem();
 434                 DB((dbg, LEVEL_1, "don't spill %+F use NoMem\n", to_spill));
 435                 return;
 436         }
 437
 438         DBG((dbg, LEVEL_1, "spilling %+F ... ", to_spill));
 439         spill = spillinfo->spills;
 440         for( ; spill != NULL; spill = spill->next) {
 441                 ir_node *block  = get_block(spill->before);
 442                 ir_node *before = spill->before;
 443
 444                 /* place all spills before the reloads (as we can't guarantee the
 445                  * same order as the be_add_spill and be_add_reload calls */
 446                 while(get_irn_idx(sched_prev(before)) > env->new_nodes_idx) {
 447                         before = sched_prev(before);
 448                 }
 449
 450                 spill->spill    = be_spill(env->arch_env, block, to_spill);
 451                 sched_add_before(before, spill->spill);
 452                 DB((dbg, LEVEL_1, "\t%+F before %+F\n", spill->spill, before));
 453 #ifdef FIRM_STATISTICS
 454                 env->spill_count++;
 455 #endif
 456         }
 457         DBG((dbg, LEVEL_1, "\n"));
 458 }
 459
 460 static void spill_node(spill_env_t *env, spill_info_t *spillinfo);
 461
 462 /**
 463  * If the first usage of a Phi result would be out of memory
 464  * there is no sense in allocating a register for it.
 465  * Thus we spill it and all its operands to the same spill slot.
 466  * Therefore the phi/dataB becomes a phi/Memory
 467  *
 468  * @param senv      the spill environment
 469  * @param phi       the Phi node that should be spilled
 470  * @param ctx_irn   an user of the spilled node
 471  */
 472 static void spill_phi(spill_env_t *env, spill_info_t *spillinfo)
 473 {
 474         ir_graph *irg   = env->irg;
 475         ir_node  *phi   = spillinfo->to_spill;
 476         ir_node  *block = get_nodes_block(phi);
 477         ir_node  *unknown;
 478         ir_node **ins;
 479         spill_t  *spill;
 480         int       i;
 481         int       arity;
 482
 483         assert(is_Phi(phi));
 484         assert(!get_opt_cse());
 485         DBG((dbg, LEVEL_1, "spilling Phi %+F:\n", phi));
 486
 487         /* build a new PhiM */
 488         arity   = get_irn_arity(phi);
 489         ins     = alloca(sizeof(ir_node*) * arity);
 490         unknown = new_r_Unknown(irg, mode_M);
 491         for(i = 0; i < arity; ++i) {
 492                 ins[i] = unknown;
 493         }
 494
 495         /* override or replace spills list... */
 496         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 497         spill->before = skip_keeps_phis(phi);
 498         spill->spill  = new_r_Phi(irg, block, arity, ins, mode_M);
 499         spill->next   = NULL;
 500
 501         spillinfo->spills = spill;
 502 #ifdef FIRM_STATISTICS
 503         env->spilled_phi_count++;
 504 #endif
 505
 506         for(i = 0; i < arity; ++i) {
 507                 ir_node      *arg      = get_irn_n(phi, i);
 508                 spill_info_t *arg_info = get_spillinfo(env, arg);
 509
 510                 determine_spill_costs(env, arg_info);
 511                 spill_node(env, arg_info);
 512
 513                 set_irn_n(spill->spill, i, arg_info->spills->spill);
 514         }
 515         DBG((dbg, LEVEL_1, "... done spilling Phi %+F, created PhiM %+F\n", phi,
 516              spill->spill));
 517 }
 518
 519 /**
 520  * Spill a node.
 521  *
 522  * @param senv      the spill environment
 523  * @param to_spill  the node that should be spilled
 524  */
 525 static void spill_node(spill_env_t *env, spill_info_t *spillinfo)
 526 {
 527         ir_node *to_spill;
 528
 529         /* node is already spilled */
 530         if(spillinfo->spills != NULL && spillinfo->spills->spill != NULL)
 531                 return;
 532
 533         to_spill = spillinfo->to_spill;
 534
 535         if (is_Phi(to_spill) && ir_nodeset_contains(&env->mem_phis, to_spill)) {
 536                 spill_phi(env, spillinfo);
 537         } else {
 538                 spill_irn(env, spillinfo);
 539         }
 540 }
 541
 542 /*
 543  *
 544  *  ____                      _            _       _ _
 545  * |  _ \ ___ _ __ ___   __ _| |_ ___ _ __(_) __ _| (_)_______
 546  * | |_) / _ \ '_ ` _ \ / _` | __/ _ \ '__| |/ _` | | |_  / _ \
 547  * |  _ <  __/ | | | | | (_| | ||  __/ |  | | (_| | | |/ /  __/
 548  * |_| \_\___|_| |_| |_|\__,_|\__\___|_|  |_|\__,_|_|_/___\___|
 549  *
 550  */
 551
 552 /**
 553  * Tests whether value @p arg is available before node @p reloader
 554  * @returns 1 if value is available, 0 otherwise
 555  */
 556 static int is_value_available(spill_env_t *env, const ir_node *arg,
 557                               const ir_node *reloader)
 558 {
 559         if(is_Unknown(arg) || arg == new_NoMem())
 560                 return 1;
 561
 562         if(be_is_Spill(arg))
 563                 return 1;
 564
 565         if(arg == get_irg_frame(env->irg))
 566                 return 1;
 567
 568         /* hack for now (happens when command should be inserted at end of block) */
 569         if(is_Block(reloader)) {
 570                 return 0;
 571         }
 572
 573         /*
 574          * Ignore registers are always available
 575          */
 576         if(arch_irn_is(env->arch_env, arg, ignore)) {
 577                 return 1;
 578         }
 579
 580         /* the following test does not work while spilling,
 581          * because the liveness info is not adapted yet to the effects of the
 582          * additional spills/reloads.
 583          */
 584 #if 0
 585         /* we want to remat before the insn reloader
 586          * thus an arguments is alive if
 587          *   - it interferes with the reloaders result
 588          *   - or it is (last-) used by reloader itself
 589          */
 590         if (values_interfere(env->birg->lv, reloader, arg)) {
 591                 return 1;
 592         }
 593
 594         arity = get_irn_arity(reloader);
 595         for (i = 0; i < arity; ++i) {
 596                 ir_node *rel_arg = get_irn_n(reloader, i);
 597                 if (rel_arg == arg)
 598                         return 1;
 599         }
 600 #endif
 601
 602         return 0;
 603 }
 604
 605 /**
 606  * Checks whether the node can principally be rematerialized
 607  */
 608 static int is_remat_node(spill_env_t *env, const ir_node *node)
 609 {
 610         const arch_env_t *arch_env = env->arch_env;
 611
 612         assert(!be_is_Spill(node));
 613
 614         if(arch_irn_is(arch_env, node, rematerializable))
 615                 return 1;
 616
 617         return 0;
 618 }
 619
 620 /**
 621  * Check if a node is rematerializable. This tests for the following conditions:
 622  *
 623  * - The node itself is rematerializable
 624  * - All arguments of the node are available or also rematerialisable
 625  * - The costs for the rematerialisation operation is less or equal a limit
 626  *
 627  * Returns the costs needed for rematerialisation or something
 628  * >= REMAT_COST_INFINITE if remat is not possible.
 629  */
 630 static int check_remat_conditions_costs(spill_env_t *env,
 631                 const ir_node *spilled, const ir_node *reloader, int parentcosts)
 632 {
 633         int i, arity;
 634         int argremats;
 635         int costs = 0;
 636
 637         if(!is_remat_node(env, spilled))
 638                 return REMAT_COST_INFINITE;
 639
 640         if(be_is_Reload(spilled)) {
 641                 costs += 2;
 642         } else {
 643                 costs += arch_get_op_estimated_cost(env->arch_env, spilled);
 644         }
 645         if(parentcosts + costs >= env->reload_cost + env->spill_cost) {
 646                 return REMAT_COST_INFINITE;
 647         }
 648         if(arch_irn_is(env->arch_env, spilled, modify_flags)) {
 649                 return REMAT_COST_INFINITE;
 650         }
 651
 652         argremats = 0;
 653         for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
 654                 ir_node *arg = get_irn_n(spilled, i);
 655
 656                 if(is_value_available(env, arg, reloader))
 657                         continue;
 658
 659                 /* we have to rematerialize the argument as well */
 660                 if(argremats >= 1) {
 661                         /* we only support rematerializing 1 argument at the moment,
 662                          * so that we don't have to care about register pressure
 663                          */
 664                         return REMAT_COST_INFINITE;
 665                 }
 666                 argremats++;
 667
 668                 costs += check_remat_conditions_costs(env, arg, reloader,
 669                                                       parentcosts + costs);
 670                 if(parentcosts + costs >= env->reload_cost + env->spill_cost)
 671                         return REMAT_COST_INFINITE;
 672         }
 673
 674         return costs;
 675 }
 676
 677 /**
 678  * Re-materialize a node.
 679  *
 680  * @param senv      the spill environment
 681  * @param spilled   the node that was spilled
 682  * @param reloader  a irn that requires a reload
 683  */
 684 static ir_node *do_remat(spill_env_t *env, ir_node *spilled, ir_node *reloader)
 685 {
 686         int i, arity;
 687         ir_node *res;
 688         ir_node *bl;
 689         ir_node **ins;
 690
 691         if(is_Block(reloader)) {
 692                 bl = reloader;
 693         } else {
 694                 bl = get_nodes_block(reloader);
 695         }
 696
 697         ins = alloca(get_irn_arity(spilled) * sizeof(ins[0]));
 698         for(i = 0, arity = get_irn_arity(spilled); i < arity; ++i) {
 699                 ir_node *arg = get_irn_n(spilled, i);
 700
 701                 if(is_value_available(env, arg, reloader)) {
 702                         ins[i] = arg;
 703                 } else {
 704                         ins[i] = do_remat(env, arg, reloader);
 705 #ifdef FIRM_STATISTICS
 706                         /* don't count the recursive call as remat */
 707                         env->remat_count--;
 708 #endif
 709                 }
 710         }
 711
 712         /* create a copy of the node */
 713         res = new_ir_node(get_irn_dbg_info(spilled), env->irg, bl,
 714                           get_irn_op(spilled), get_irn_mode(spilled),
 715                           get_irn_arity(spilled), ins);
 716         copy_node_attr(spilled, res);
 717         new_backedge_info(res);
 718
 719         DBG((dbg, LEVEL_1, "Insert remat %+F of %+F before reloader %+F\n", res, spilled, reloader));
 720
 721         if (! is_Proj(res)) {
 722                 /* insert in schedule */
 723                 sched_reset(res);
 724                 sched_add_before(reloader, res);
 725 #ifdef FIRM_STATISTICS
 726                 env->remat_count++;
 727 #endif
 728         }
 729
 730         return res;
 731 }
 732
 733 double be_get_spill_costs(spill_env_t *env, ir_node *to_spill, ir_node *before)
 734 {
 735         ir_node *block = get_nodes_block(before);
 736         double   freq  = get_block_execfreq(env->exec_freq, block);
 737         (void) to_spill;
 738
 739         return env->spill_cost * freq;
 740 }
 741
 742 unsigned be_get_reload_costs_no_weight(spill_env_t *env, const ir_node *to_spill,
 743                                        const ir_node *before)
 744 {
 745         if(be_do_remats) {
 746                 /* is the node rematerializable? */
 747                 unsigned costs = check_remat_conditions_costs(env, to_spill, before, 0);
 748                 if(costs < (unsigned) env->reload_cost)
 749                         return costs;
 750         }
 751
 752         return env->reload_cost;
 753 }
 754
 755 double be_get_reload_costs(spill_env_t *env, ir_node *to_spill, ir_node *before)
 756 {
 757         ir_node      *block = get_nodes_block(before);
 758         double        freq  = get_block_execfreq(env->exec_freq, block);
 759
 760         if(be_do_remats) {
 761                 /* is the node rematerializable? */
 762                 int costs = check_remat_conditions_costs(env, to_spill, before, 0);
 763                 if(costs < env->reload_cost)
 764                         return costs * freq;
 765         }
 766
 767         return env->reload_cost * freq;
 768 }
 769
 770 int be_is_rematerializable(spill_env_t *env, const ir_node *to_remat,
 771                            const ir_node *before)
 772 {
 773         return check_remat_conditions_costs(env, to_remat, before, 0) < REMAT_COST_INFINITE;
 774 }
 775
 776 double be_get_reload_costs_on_edge(spill_env_t *env, ir_node *to_spill,
 777                                    ir_node *block, int pos)
 778 {
 779         ir_node *before = get_block_insertion_point(block, pos);
 780         return be_get_reload_costs(env, to_spill, before);
 781 }
 782
 783 /*
 784  *  ___                     _     ____      _                 _
 785  * |_ _|_ __  ___  ___ _ __| |_  |  _ \ ___| | ___   __ _  __| |___
 786  *  | || '_ \/ __|/ _ \ '__| __| | |_) / _ \ |/ _ \ / _` |/ _` / __|
 787  *  | || | | \__ \  __/ |  | |_  |  _ <  __/ | (_) | (_| | (_| \__ \
 788  * |___|_| |_|___/\___|_|   \__| |_| \_\___|_|\___/ \__,_|\__,_|___/
 789  *
 790  */
 791
 792 /**
 793  * analyzes how to best spill a node and determine costs for that
 794  */
 795 static void determine_spill_costs(spill_env_t *env, spill_info_t *spillinfo)
 796 {
 797         ir_node *to_spill = spillinfo->to_spill;
 798         ir_node *spill_block;
 799         spill_t *spill;
 800         double   spill_execfreq;
 801
 802         /* already calculated? */
 803         if(spillinfo->spill_costs >= 0)
 804                 return;
 805
 806         assert(! arch_irn_is(env->arch_env, to_spill, dont_spill));
 807         assert(!be_is_Reload(to_spill));
 808
 809         /* some backends have virtual noreg/unknown nodes that are not scheduled
 810          * and simply always available.
 811          * TODO: this is kinda hairy, the NoMem is correct for an Unknown as Phi
 812          * predecessor (of a PhiM) but this test might match other things too...
 813          */
 814         if(!sched_is_scheduled(to_spill)) {
 815                 /* override spillinfos or create a new one */
 816                 spill_t *spill = obstack_alloc(&env->obst, sizeof(spill[0]));
 817                 spill->before  = NULL;
 818                 spill->next    = NULL;
 819                 spill->spill   = new_NoMem();
 820
 821                 spillinfo->spills      = spill;
 822                 spillinfo->spill_costs = 0;
 823
 824                 DB((dbg, LEVEL_1, "don't spill %+F use NoMem\n", to_spill));
 825                 return;
 826         }
 827
 828         spill_block    = get_nodes_block(to_spill);
 829         spill_execfreq = get_block_execfreq(env->exec_freq, spill_block);
 830
 831         if (is_Phi(to_spill) && ir_nodeset_contains(&env->mem_phis, to_spill)) {
 832                 /* TODO calculate correct costs...
 833                  * (though we can't remat this node anyway so no big problem) */
 834                 spillinfo->spill_costs = env->spill_cost * spill_execfreq;
 835                 return;
 836         }
 837
 838         if(spillinfo->spills != NULL) {
 839                 spill_t *s;
 840                 double   spills_execfreq;
 841
 842                 /* calculate sum of executaion frequencies of individual spills */
 843                 spills_execfreq = 0;
 844                 s               = spillinfo->spills;
 845                 for( ; s != NULL; s = s->next) {
 846                         ir_node *spill_block = s->before;
 847                         double   freq;
 848
 849                         if(!is_Block(spill_block)) {
 850                                 spill_block = get_nodes_block(spill_block);
 851                         }
 852                         freq = get_block_execfreq(env->exec_freq, spill_block);
 853
 854                         spills_execfreq += freq;
 855                 }
 856
 857                 DB((dbg, LEVEL_1, "%+F: latespillcosts %f after def: %f\n", to_spill,
 858                     spills_execfreq * env->spill_cost,
 859                     spill_execfreq * env->spill_cost));
 860
 861                 /* multi-/latespill is advantageous -> return*/
 862                 if(spills_execfreq < spill_execfreq) {
 863                         DB((dbg, LEVEL_1, "use latespills for %+F\n", to_spill));
 864                         spillinfo->spill_costs = spills_execfreq * env->spill_cost;
 865                         return;
 866                 }
 867         }
 868
 869         /* override spillinfos or create a new one */
 870         spill         = obstack_alloc(&env->obst, sizeof(spill[0]));
 871         spill->before = skip_keeps_phis(to_spill);
 872         spill->next   = NULL;
 873         spill->spill  = NULL;
 874
 875         spillinfo->spills      = spill;
 876         spillinfo->spill_costs = spill_execfreq * env->spill_cost;
 877         DB((dbg, LEVEL_1, "spill %+F after definition\n", to_spill));
 878 }
 879
 880 void be_insert_spills_reloads(spill_env_t *env)
 881 {
 882         ir_graph              *irg       = env->irg;
 883         const arch_env_t      *arch_env  = env->arch_env;
 884         const ir_exec_freq    *exec_freq = env->exec_freq;
 885         spill_info_t          *si;
 886         ir_nodeset_iterator_t  iter;
 887         ir_node               *node;
 888
 889         env->new_nodes_idx = get_irg_last_idx(irg);
 890
 891         /* create all phi-ms first, this is needed so, that phis, hanging on
 892            spilled phis work correctly */
 893         foreach_ir_nodeset(&env->mem_phis, node, iter) {
 894                 spill_info_t *info = get_spillinfo(env, node);
 895                 spill_node(env, info);
 896         }
 897
 898         /* process each spilled node */
 899         for (si = set_first(env->spills); si; si = set_next(env->spills)) {
 900                 reloader_t *rld;
 901                 ir_node  *to_spill        = si->to_spill;
 902                 ir_mode  *mode            = get_irn_mode(to_spill);
 903                 ir_node **copies          = NEW_ARR_F(ir_node*, 0);
 904                 double    all_remat_costs = 0; /** costs when we would remat all nodes */
 905                 int       force_remat     = 0;
 906
 907                 DBG((dbg, LEVEL_1, "\nhandling all reloaders of %+F:\n", to_spill));
 908
 909                 determine_spill_costs(env, si);
 910
 911                 /* determine possibility of rematerialisations */
 912                 if(be_do_remats) {
 913                         /* calculate cost savings for each indivial value when it would
 914                            be rematted instead of reloaded */
 915                         for (rld = si->reloaders; rld != NULL; rld = rld->next) {
 916                                 double   freq;
 917                                 int      remat_cost;
 918                                 int      remat_cost_delta;
 919                                 ir_node *block;
 920                                 ir_node *reloader = rld->reloader;
 921
 922                                 if(rld->rematted_node != NULL) {
 923                                         DBG((dbg, LEVEL_2, "\tforced remat %+F before %+F\n",
 924                                              rld->rematted_node, reloader));
 925                                         continue;
 926                                 }
 927                                 if(rld->remat_cost_delta >= REMAT_COST_INFINITE) {
 928                                         DBG((dbg, LEVEL_2, "\treload before %+F is forbidden\n",
 929                                              reloader));
 930                                         all_remat_costs = REMAT_COST_INFINITE;
 931                                         continue;
 932                                 }
 933
 934                                 remat_cost  = check_remat_conditions_costs(env, to_spill,
 935                                                                            reloader, 0);
 936                                 if(remat_cost >= REMAT_COST_INFINITE) {
 937                                         DBG((dbg, LEVEL_2, "\tremat before %+F not possible\n",
 938                                              reloader));
 939                                         rld->remat_cost_delta = REMAT_COST_INFINITE;
 940                                         all_remat_costs       = REMAT_COST_INFINITE;
 941                                         continue;
 942                                 }
 943
 944                                 remat_cost_delta      = remat_cost - env->reload_cost;
 945                                 rld->remat_cost_delta = remat_cost_delta;
 946                                 block                 = is_Block(reloader) ? reloader : get_nodes_block(reloader);
 947                                 freq                  = get_block_execfreq(exec_freq, block);
 948                                 all_remat_costs      += remat_cost_delta * freq;
 949                                 DBG((dbg, LEVEL_2, "\tremat costs delta before %+F: "
 950                                      "%d (rel %f)\n", reloader, remat_cost_delta,
 951                                      remat_cost_delta * freq));
 952                         }
 953                         if(all_remat_costs < REMAT_COST_INFINITE) {
 954                                 /* we don't need the costs for the spill if we can remat
 955                                    all reloaders */
 956                                 all_remat_costs -= si->spill_costs;
 957
 958                                 DBG((dbg, LEVEL_2, "\tspill costs %d (rel %f)\n",
 959                                      env->spill_cost, si->spill_costs));
 960                         }
 961
 962                         if(all_remat_costs < 0) {
 963                                 DBG((dbg, LEVEL_1, "\nforcing remats of all reloaders (%f)\n",
 964                                      all_remat_costs));
 965                                 force_remat = 1;
 966                         }
 967                 }
 968
 969                 /* go through all reloads for this spill */
 970                 for (rld = si->reloaders; rld != NULL; rld = rld->next) {
 971                         ir_node *copy; /* a reload is a "copy" of the original value */
 972
 973                         if (rld->rematted_node != NULL) {
 974                                 copy = rld->rematted_node;
 975                                 sched_add_before(rld->reloader, copy);
 976                         } else if (be_do_remats &&
 977                                         (force_remat || rld->remat_cost_delta < 0)) {
 978                                 copy = do_remat(env, to_spill, rld->reloader);
 979                         } else {
 980                                 /* make sure we have a spill */
 981                                 spill_node(env, si);
 982
 983                                 /* create a reload, use the first spill for now SSA
 984                                  * reconstruction for memory comes below */
 985                                 assert(si->spills != NULL);
 986                                 copy = be_reload(arch_env, si->reload_cls, rld->reloader, mode,
 987                                                  si->spills->spill);
 988 #ifdef FIRM_STATISTICS
 989                                 env->reload_count++;
 990 #endif
 991                         }
 992
 993                         DBG((dbg, LEVEL_1, " %+F of %+F before %+F\n",
 994                              copy, to_spill, rld->reloader));
 995                         ARR_APP1(ir_node*, copies, copy);
 996                 }
 997
 998                 /* if we had any reloads or remats, then we need to reconstruct the
 999                  * SSA form for the spilled value */
1000                 if (ARR_LEN(copies) > 0) {
1001                         be_ssa_construction_env_t senv;
1002                         /* be_lv_t *lv = be_get_birg_liveness(env->birg); */
1003
1004                         be_ssa_construction_init(&senv, env->birg);
1005                         be_ssa_construction_add_copy(&senv, to_spill);
1006                         be_ssa_construction_add_copies(&senv, copies, ARR_LEN(copies));
1007                         be_ssa_construction_fix_users(&senv, to_spill);
1008
1009 #if 0
1010                         /* no need to enable this as long as we invalidate liveness
1011                            after this function... */
1012                         be_ssa_construction_update_liveness_phis(&senv);
1013                         be_liveness_update(to_spill);
1014                         len = ARR_LEN(copies);
1015                         for(i = 0; i < len; ++i) {
1016                                 be_liveness_update(lv, copies[i]);
1017                         }
1018 #endif
1019                         be_ssa_construction_destroy(&senv);
1020                 }
1021                 /* need to reconstruct SSA form if we had multiple spills */
1022                 if (si->spills != NULL && si->spills->next != NULL) {
1023                         spill_t *spill;
1024                         int      spill_count = 0;
1025
1026                         be_ssa_construction_env_t senv;
1027
1028                         be_ssa_construction_init(&senv, env->birg);
1029                         spill = si->spills;
1030                         for( ; spill != NULL; spill = spill->next) {
1031                                 /* maybe we rematerialized the value and need no spill */
1032                                 if(spill->spill == NULL)
1033                                         continue;
1034                                 be_ssa_construction_add_copy(&senv, spill->spill);
1035                                 spill_count++;
1036                         }
1037                         if(spill_count > 1) {
1038                                 /* all reloads are attached to the first spill, fix them now */
1039                                 be_ssa_construction_fix_users(&senv, si->spills->spill);
1040                         }
1041
1042                         be_ssa_construction_destroy(&senv);
1043                 }
1044
1045                 DEL_ARR_F(copies);
1046                 si->reloaders = NULL;
1047         }
1048
1049         stat_ev_dbl("spill_spills", env->spill_count);
1050         stat_ev_dbl("spill_reloads", env->reload_count);
1051         stat_ev_dbl("spill_remats", env->remat_count);
1052         stat_ev_dbl("spill_spilled_phis", env->spilled_phi_count);
1053
1054         /* Matze: In theory be_ssa_construction should take care of the liveness...
1055          * try to disable this again in the future */
1056         be_liveness_invalidate(env->birg->lv);
1057
1058         be_remove_dead_nodes_from_schedule(env->birg);
1059 }
1060
1061 void be_init_spill(void)
1062 {
1063         FIRM_DBG_REGISTER(dbg, "firm.be.spill");
1064 }
1065
1066 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_spill);