nsz Git - libfirm/blob - ir/be/beprefalloc.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       Preference Guided Register Assignment
  23  * @author      Matthias Braun
  24  * @date        14.2.2009
  25  * @version     $Id$
  26  *
  27  * The idea is to allocate registers in 2 passes:
  28  * 1. A first pass to determine "preferred" registers for live-ranges. This
  29  *    calculates for each register and each live-range a value indicating
  30  *    the usefulness. (You can roughly think of the value as the negative
  31  *    costs needed for copies when the value is in the specific registers...)
  32  *
  33  * 2. Walk blocks and assigns registers in a greedy fashion. Preferring
  34  *    registers with high preferences. When register constraints are not met,
  35  *    add copies and split live-ranges.
  36  *
  37  * TODO:
  38  *  - make use of free registers in the permute_values code
  39  */
  40 #include "config.h"
  41
  42 #include <float.h>
  43 #include <stdbool.h>
  44 #include <math.h>
  45
  46 #include "error.h"
  47 #include "execfreq.h"
  48 #include "ircons.h"
  49 #include "irdom.h"
  50 #include "iredges_t.h"
  51 #include "irgraph_t.h"
  52 #include "irgwalk.h"
  53 #include "irnode_t.h"
  54 #include "irprintf.h"
  55 #include "irdump.h"
  56 #include "obst.h"
  57 #include "raw_bitset.h"
  58 #include "unionfind.h"
  59 #include "pdeq.h"
  60 #include "hungarian.h"
  61
  62 #include "beabi.h"
  63 #include "bechordal_t.h"
  64 #include "be.h"
  65 #include "beirg.h"
  66 #include "belive_t.h"
  67 #include "bemodule.h"
  68 #include "benode.h"
  69 #include "bera.h"
  70 #include "besched.h"
  71 #include "bespill.h"
  72 #include "bespillutil.h"
  73 #include "beverify.h"
  74 #include "beutil.h"
  75
  76 #define USE_FACTOR                     1.0f
  77 #define DEF_FACTOR                     1.0f
  78 #define NEIGHBOR_FACTOR                0.2f
  79 #define AFF_SHOULD_BE_SAME             0.5f
  80 #define AFF_PHI                        1.0f
  81 #define SPLIT_DELTA                    1.0f
  82 #define MAX_OPTIMISTIC_SPLIT_RECURSION 0
  83
  84 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  85
  86 static struct obstack               obst;
  87 static be_irg_t                    *birg;
  88 static ir_graph                    *irg;
  89 static const arch_register_class_t *cls;
  90 static const arch_register_req_t   *default_cls_req;
  91 static be_lv_t                     *lv;
  92 static const ir_exec_freq          *execfreqs;
  93 static unsigned                     n_regs;
  94 static unsigned                    *normal_regs;
  95 static int                         *congruence_classes;
  96 static ir_node                    **block_order;
  97 static int                          n_block_order;
  98 static int                          create_preferences        = true;
  99 static int                          create_congruence_classes = true;
 100 static int                          propagate_phi_registers   = true;
 101
 102 static const lc_opt_table_entry_t options[] = {
 103         LC_OPT_ENT_BOOL("prefs", "use preference based coloring", &create_preferences),
 104         LC_OPT_ENT_BOOL("congruences", "create congruence classes", &create_congruence_classes),
 105         LC_OPT_ENT_BOOL("prop_phi", "propagate phi registers", &propagate_phi_registers),
 106         LC_OPT_LAST
 107 };
 108
 109 /** currently active assignments (while processing a basic block)
 110  * maps registers to values(their current copies) */
 111 static ir_node **assignments;
 112
 113 /**
 114  * allocation information: last_uses, register preferences
 115  * the information is per firm-node.
 116  */
 117 struct allocation_info_t {
 118         unsigned  last_uses;      /**< bitset indicating last uses (input pos) */
 119         ir_node  *current_value;  /**< copy of the value that should be used */
 120         ir_node  *original_value; /**< for copies point to original value */
 121         float     prefs[0];       /**< register preferences */
 122 };
 123 typedef struct allocation_info_t allocation_info_t;
 124
 125 /** helper datastructure used when sorting register preferences */
 126 struct reg_pref_t {
 127         unsigned num;
 128         float    pref;
 129 };
 130 typedef struct reg_pref_t reg_pref_t;
 131
 132 /** per basic-block information */
 133 struct block_info_t {
 134         bool     processed;       /**< indicate whether block is processed */
 135         ir_node *assignments[0];  /**< register assignments at end of block */
 136 };
 137 typedef struct block_info_t block_info_t;
 138
 139 /**
 140  * Get the allocation info for a node.
 141  * The info is allocated on the first visit of a node.
 142  */
 143 static allocation_info_t *get_allocation_info(ir_node *node)
 144 {
 145         allocation_info_t *info = get_irn_link(node);
 146         if (info == NULL) {
 147                 info = OALLOCFZ(&obst, allocation_info_t, prefs, n_regs);
 148                 info->current_value  = node;
 149                 info->original_value = node;
 150                 set_irn_link(node, info);
 151         }
 152
 153         return info;
 154 }
 155
 156 static allocation_info_t *try_get_allocation_info(const ir_node *node)
 157 {
 158         return (allocation_info_t*) get_irn_link(node);
 159 }
 160
 161 /**
 162  * Get allocation information for a basic block
 163  */
 164 static block_info_t *get_block_info(ir_node *block)
 165 {
 166         block_info_t *info = get_irn_link(block);
 167
 168         assert(is_Block(block));
 169         if (info == NULL) {
 170                 info = OALLOCFZ(&obst, block_info_t, assignments, n_regs);
 171                 set_irn_link(block, info);
 172         }
 173
 174         return info;
 175 }
 176
 177 /**
 178  * Get default register requirement for the current register class
 179  */
 180 static const arch_register_req_t *get_default_req_current_cls(void)
 181 {
 182         if (default_cls_req == NULL) {
 183                 struct obstack      *obst = get_irg_obstack(irg);
 184                 arch_register_req_t *req  = OALLOCZ(obst, arch_register_req_t);
 185
 186                 req->type = arch_register_req_type_normal;
 187                 req->cls  = cls;
 188
 189                 default_cls_req = req;
 190         }
 191         return default_cls_req;
 192 }
 193
 194 /**
 195  * Link the allocation info of a node to a copy.
 196  * Afterwards, both nodes uses the same allocation info.
 197  * Copy must not have an allocation info assigned yet.
 198  *
 199  * @param copy   the node that gets the allocation info assigned
 200  * @param value  the original node
 201  */
 202 static void mark_as_copy_of(ir_node *copy, ir_node *value)
 203 {
 204         ir_node           *original;
 205         allocation_info_t *info      = get_allocation_info(value);
 206         allocation_info_t *copy_info = get_allocation_info(copy);
 207
 208         /* find original value */
 209         original = info->original_value;
 210         if (original != value) {
 211                 info = get_allocation_info(original);
 212         }
 213
 214         assert(info->original_value == original);
 215         info->current_value = copy;
 216
 217         /* the copy should not be linked to something else yet */
 218         assert(copy_info->original_value == copy);
 219         copy_info->original_value = original;
 220
 221         /* copy over allocation preferences */
 222         memcpy(copy_info->prefs, info->prefs, n_regs * sizeof(copy_info->prefs[0]));
 223 }
 224
 225 /**
 226  * Calculate the penalties for every register on a node and its live neighbors.
 227  *
 228  * @param live_nodes  the set of live nodes at the current position, may be NULL
 229  * @param penalty     the penalty to subtract from
 230  * @param limited     a raw bitset containing the limited set for the node
 231  * @param node        the node
 232  */
 233 static void give_penalties_for_limits(const ir_nodeset_t *live_nodes,
 234                                       float penalty, const unsigned* limited,
 235                                       ir_node *node)
 236 {
 237         ir_nodeset_iterator_t iter;
 238         unsigned              r;
 239         unsigned              n_allowed;
 240         allocation_info_t     *info = get_allocation_info(node);
 241         ir_node               *neighbor;
 242
 243         /* give penalty for all forbidden regs */
 244         for (r = 0; r < n_regs; ++r) {
 245                 if (rbitset_is_set(limited, r))
 246                         continue;
 247
 248                 info->prefs[r] -= penalty;
 249         }
 250
 251         /* all other live values should get a penalty for allowed regs */
 252         if (live_nodes == NULL)
 253                 return;
 254
 255         penalty   *= NEIGHBOR_FACTOR;
 256         n_allowed  = rbitset_popcount(limited, n_regs);
 257         if (n_allowed > 1) {
 258                 /* only create a very weak penalty if multiple regs are allowed */
 259                 penalty = (penalty * 0.8f) / n_allowed;
 260         }
 261         foreach_ir_nodeset(live_nodes, neighbor, iter) {
 262                 allocation_info_t *neighbor_info;
 263
 264                 /* TODO: if op is used on multiple inputs we might not do a
 265                  * continue here */
 266                 if (neighbor == node)
 267                         continue;
 268
 269                 neighbor_info = get_allocation_info(neighbor);
 270                 for (r = 0; r < n_regs; ++r) {
 271                         if (!rbitset_is_set(limited, r))
 272                                 continue;
 273
 274                         neighbor_info->prefs[r] -= penalty;
 275                 }
 276         }
 277 }
 278
 279 /**
 280  * Calculate the preferences of a definition for the current register class.
 281  * If the definition uses a limited set of registers, reduce the preferences
 282  * for the limited register on the node and its neighbors.
 283  *
 284  * @param live_nodes  the set of live nodes at the current node
 285  * @param weight      the weight
 286  * @param node        the current node
 287  */
 288 static void check_defs(const ir_nodeset_t *live_nodes, float weight,
 289                        ir_node *node)
 290 {
 291         const arch_register_req_t *req;
 292
 293         if (get_irn_mode(node) == mode_T) {
 294                 const ir_edge_t *edge;
 295                 foreach_out_edge(node, edge) {
 296                         ir_node *proj = get_edge_src_irn(edge);
 297                         check_defs(live_nodes, weight, proj);
 298                 }
 299                 return;
 300         }
 301
 302         if (!arch_irn_consider_in_reg_alloc(cls, node))
 303                 return;
 304
 305         req = arch_get_register_req_out(node);
 306         if (req->type & arch_register_req_type_limited) {
 307                 const unsigned *limited = req->limited;
 308                 float           penalty = weight * DEF_FACTOR;
 309                 give_penalties_for_limits(live_nodes, penalty, limited, node);
 310         }
 311
 312         if (req->type & arch_register_req_type_should_be_same) {
 313                 ir_node           *insn  = skip_Proj(node);
 314                 allocation_info_t *info  = get_allocation_info(node);
 315                 int                arity = get_irn_arity(insn);
 316                 int                i;
 317
 318                 float factor = 1.0f / rbitset_popcount(&req->other_same, arity);
 319                 for (i = 0; i < arity; ++i) {
 320                         ir_node           *op;
 321                         unsigned           r;
 322                         allocation_info_t *op_info;
 323
 324                         if (!rbitset_is_set(&req->other_same, i))
 325                                 continue;
 326
 327                         op = get_irn_n(insn, i);
 328
 329                         /* if we the value at the should_be_same input doesn't die at the
 330                          * node, then it is no use to propagate the constraints (since a
 331                          * copy will emerge anyway) */
 332                         if (ir_nodeset_contains(live_nodes, op))
 333                                 continue;
 334
 335                         op_info = get_allocation_info(op);
 336                         for (r = 0; r < n_regs; ++r) {
 337                                 op_info->prefs[r] += info->prefs[r] * factor;
 338                         }
 339                 }
 340         }
 341 }
 342
 343 /**
 344  * Walker: Runs an a block calculates the preferences for any
 345  * node and every register from the considered register class.
 346  */
 347 static void analyze_block(ir_node *block, void *data)
 348 {
 349         float         weight = (float)get_block_execfreq(execfreqs, block);
 350         ir_nodeset_t  live_nodes;
 351         ir_node      *node;
 352         (void) data;
 353
 354         ir_nodeset_init(&live_nodes);
 355         be_liveness_end_of_block(lv, cls, block, &live_nodes);
 356
 357         sched_foreach_reverse(block, node) {
 358                 allocation_info_t *info;
 359                 int                i;
 360                 int                arity;
 361
 362                 if (is_Phi(node))
 363                         break;
 364
 365                 if (create_preferences)
 366                         check_defs(&live_nodes, weight, node);
 367
 368                 /* mark last uses */
 369                 arity = get_irn_arity(node);
 370
 371                 /* the allocation info node currently only uses 1 unsigned value
 372                    to mark last used inputs. So we will fail for a node with more than
 373                    32 inputs. */
 374                 if (arity >= (int) sizeof(unsigned) * 8) {
 375                         panic("Node with more than %d inputs not supported yet",
 376                                         (int) sizeof(unsigned) * 8);
 377                 }
 378
 379                 info = get_allocation_info(node);
 380                 for (i = 0; i < arity; ++i) {
 381                         ir_node *op = get_irn_n(node, i);
 382                         if (!arch_irn_consider_in_reg_alloc(cls, op))
 383                                 continue;
 384
 385                         /* last usage of a value? */
 386                         if (!ir_nodeset_contains(&live_nodes, op)) {
 387                                 rbitset_set(&info->last_uses, i);
 388                         }
 389                 }
 390
 391                 be_liveness_transfer(cls, node, &live_nodes);
 392
 393                 if (create_preferences) {
 394                         /* update weights based on usage constraints */
 395                         for (i = 0; i < arity; ++i) {
 396                                 const arch_register_req_t *req;
 397                                 const unsigned            *limited;
 398                                 ir_node                   *op = get_irn_n(node, i);
 399
 400                                 if (!arch_irn_consider_in_reg_alloc(cls, op))
 401                                         continue;
 402
 403                                 req = arch_get_register_req(node, i);
 404                                 if (!(req->type & arch_register_req_type_limited))
 405                                         continue;
 406
 407                                 limited = req->limited;
 408                                 give_penalties_for_limits(&live_nodes, weight * USE_FACTOR,
 409                                                           limited, op);
 410                         }
 411                 }
 412         }
 413
 414         ir_nodeset_destroy(&live_nodes);
 415 }
 416
 417 static void congruence_def(ir_nodeset_t *live_nodes, ir_node *node)
 418 {
 419         const arch_register_req_t *req;
 420
 421         if (get_irn_mode(node) == mode_T) {
 422                 const ir_edge_t *edge;
 423                 foreach_out_edge(node, edge) {
 424                         ir_node *def = get_edge_src_irn(edge);
 425                         congruence_def(live_nodes, def);
 426                 }
 427                 return;
 428         }
 429
 430         if (!arch_irn_consider_in_reg_alloc(cls, node))
 431                 return;
 432
 433         /* should be same constraint? */
 434         req = arch_get_register_req_out(node);
 435         if (req->type & arch_register_req_type_should_be_same) {
 436                 ir_node *insn  = skip_Proj(node);
 437                 int      arity = get_irn_arity(insn);
 438                 int      i;
 439                 unsigned node_idx = get_irn_idx(node);
 440                 node_idx          = uf_find(congruence_classes, node_idx);
 441
 442                 for (i = 0; i < arity; ++i) {
 443                         ir_node               *live;
 444                         ir_node               *op;
 445                         int                    op_idx;
 446                         ir_nodeset_iterator_t  iter;
 447                         bool                   interferes = false;
 448
 449                         if (!rbitset_is_set(&req->other_same, i))
 450                                 continue;
 451
 452                         op     = get_irn_n(insn, i);
 453                         op_idx = get_irn_idx(op);
 454                         op_idx = uf_find(congruence_classes, op_idx);
 455
 456                         /* do we interfere with the value */
 457                         foreach_ir_nodeset(live_nodes, live, iter) {
 458                                 int lv_idx = get_irn_idx(live);
 459                                 lv_idx     = uf_find(congruence_classes, lv_idx);
 460                                 if (lv_idx == op_idx) {
 461                                         interferes = true;
 462                                         break;
 463                                 }
 464                         }
 465                         /* don't put in same affinity class if we interfere */
 466                         if (interferes)
 467                                 continue;
 468
 469                         node_idx = uf_union(congruence_classes, node_idx, op_idx);
 470                         DB((dbg, LEVEL_3, "Merge %+F and %+F congruence classes\n",
 471                             node, op));
 472                         /* one should_be_same is enough... */
 473                         break;
 474                 }
 475         }
 476 }
 477
 478 static void create_congruence_class(ir_node *block, void *data)
 479 {
 480         ir_nodeset_t  live_nodes;
 481         ir_node      *node;
 482
 483         (void) data;
 484         ir_nodeset_init(&live_nodes);
 485         be_liveness_end_of_block(lv, cls, block, &live_nodes);
 486
 487         /* check should be same constraints */
 488         sched_foreach_reverse(block, node) {
 489                 if (is_Phi(node))
 490                         break;
 491
 492                 congruence_def(&live_nodes, node);
 493                 be_liveness_transfer(cls, node, &live_nodes);
 494         }
 495
 496         /* check phi congruence classes */
 497         sched_foreach_reverse_from(node, node) {
 498                 int i;
 499                 int arity;
 500                 int node_idx;
 501                 assert(is_Phi(node));
 502
 503                 if (!arch_irn_consider_in_reg_alloc(cls, node))
 504                         continue;
 505
 506                 node_idx = get_irn_idx(node);
 507                 node_idx = uf_find(congruence_classes, node_idx);
 508
 509                 arity = get_irn_arity(node);
 510                 for (i = 0; i < arity; ++i) {
 511                         bool                  interferes = false;
 512                         ir_nodeset_iterator_t iter;
 513                         unsigned              r;
 514                         int                   old_node_idx;
 515                         ir_node              *live;
 516                         ir_node              *phi;
 517                         allocation_info_t    *head_info;
 518                         allocation_info_t    *other_info;
 519                         ir_node              *op     = get_Phi_pred(node, i);
 520                         int                   op_idx = get_irn_idx(op);
 521                         op_idx = uf_find(congruence_classes, op_idx);
 522
 523                         /* do we interfere with the value */
 524                         foreach_ir_nodeset(&live_nodes, live, iter) {
 525                                 int lv_idx = get_irn_idx(live);
 526                                 lv_idx     = uf_find(congruence_classes, lv_idx);
 527                                 if (lv_idx == op_idx) {
 528                                         interferes = true;
 529                                         break;
 530                                 }
 531                         }
 532                         /* don't put in same affinity class if we interfere */
 533                         if (interferes)
 534                                 continue;
 535                         /* any other phi has the same input? */
 536                         sched_foreach(block, phi) {
 537                                 ir_node *oop;
 538                                 int      oop_idx;
 539                                 if (!is_Phi(phi))
 540                                         break;
 541                                 if (!arch_irn_consider_in_reg_alloc(cls, phi))
 542                                         continue;
 543                                 oop = get_Phi_pred(phi, i);
 544                                 if (oop == op)
 545                                         continue;
 546                                 oop_idx = get_irn_idx(oop);
 547                                 oop_idx = uf_find(congruence_classes, oop_idx);
 548                                 if (oop_idx == op_idx) {
 549                                         interferes = true;
 550                                         break;
 551                                 }
 552                         }
 553                         if (interferes)
 554                                 continue;
 555
 556                         /* merge the 2 congruence classes and sum up their preferences */
 557                         old_node_idx = node_idx;
 558                         node_idx = uf_union(congruence_classes, node_idx, op_idx);
 559                         DB((dbg, LEVEL_3, "Merge %+F and %+F congruence classes\n",
 560                             node, op));
 561
 562                         old_node_idx = node_idx == old_node_idx ? op_idx : old_node_idx;
 563                         head_info  = get_allocation_info(get_idx_irn(irg, node_idx));
 564                         other_info = get_allocation_info(get_idx_irn(irg, old_node_idx));
 565                         for (r = 0; r < n_regs; ++r) {
 566                                 head_info->prefs[r] += other_info->prefs[r];
 567                         }
 568                 }
 569         }
 570 }
 571
 572 static void set_congruence_prefs(ir_node *node, void *data)
 573 {
 574         allocation_info_t *info;
 575         allocation_info_t *head_info;
 576         unsigned node_idx = get_irn_idx(node);
 577         unsigned node_set = uf_find(congruence_classes, node_idx);
 578
 579         (void) data;
 580
 581         /* head of congruence class or not in any class */
 582         if (node_set == node_idx)
 583                 return;
 584
 585         if (!arch_irn_consider_in_reg_alloc(cls, node))
 586                 return;
 587
 588         head_info = get_allocation_info(get_idx_irn(irg, node_set));
 589         info      = get_allocation_info(node);
 590
 591         memcpy(info->prefs, head_info->prefs, n_regs * sizeof(info->prefs[0]));
 592 }
 593
 594 static void combine_congruence_classes(void)
 595 {
 596         size_t n = get_irg_last_idx(irg);
 597         congruence_classes = XMALLOCN(int, n);
 598         uf_init(congruence_classes, n);
 599
 600         /* create congruence classes */
 601         irg_block_walk_graph(irg, create_congruence_class, NULL, NULL);
 602         /* merge preferences */
 603         irg_walk_graph(irg, set_congruence_prefs, NULL, NULL);
 604         free(congruence_classes);
 605 }
 606
 607
 608
 609
 610
 611 /**
 612  * Assign register reg to the given node.
 613  *
 614  * @param node  the node
 615  * @param reg   the register
 616  */
 617 static void use_reg(ir_node *node, const arch_register_t *reg)
 618 {
 619         unsigned r = arch_register_get_index(reg);
 620         assignments[r] = node;
 621         arch_set_irn_register(node, reg);
 622 }
 623
 624 static void free_reg_of_value(ir_node *node)
 625 {
 626         const arch_register_t *reg;
 627         unsigned               r;
 628
 629         if (!arch_irn_consider_in_reg_alloc(cls, node))
 630                 return;
 631
 632         reg        = arch_get_irn_register(node);
 633         r          = arch_register_get_index(reg);
 634         /* assignment->value may be NULL if a value is used at 2 inputs
 635            so it gets freed twice. */
 636         assert(assignments[r] == node || assignments[r] == NULL);
 637         assignments[r] = NULL;
 638 }
 639
 640 /**
 641  * Compare two register preferences in decreasing order.
 642  */
 643 static int compare_reg_pref(const void *e1, const void *e2)
 644 {
 645         const reg_pref_t *rp1 = (const reg_pref_t*) e1;
 646         const reg_pref_t *rp2 = (const reg_pref_t*) e2;
 647         if (rp1->pref < rp2->pref)
 648                 return 1;
 649         if (rp1->pref > rp2->pref)
 650                 return -1;
 651         return 0;
 652 }
 653
 654 static void fill_sort_candidates(reg_pref_t *regprefs,
 655                                  const allocation_info_t *info)
 656 {
 657         unsigned r;
 658
 659         for (r = 0; r < n_regs; ++r) {
 660                 float pref = info->prefs[r];
 661                 regprefs[r].num  = r;
 662                 regprefs[r].pref = pref;
 663         }
 664         /* TODO: use a stable sort here to avoid unnecessary register jumping */
 665         qsort(regprefs, n_regs, sizeof(regprefs[0]), compare_reg_pref);
 666 }
 667
 668 static bool try_optimistic_split(ir_node *to_split, ir_node *before,
 669                                  float pref, float pref_delta,
 670                                  unsigned *forbidden_regs, int recursion)
 671 {
 672         const arch_register_t *from_reg;
 673         const arch_register_t *reg;
 674         ir_node               *original_insn;
 675         ir_node               *block;
 676         ir_node               *copy;
 677         unsigned               r;
 678         unsigned               from_r;
 679         unsigned               i;
 680         allocation_info_t     *info = get_allocation_info(to_split);
 681         reg_pref_t            *prefs;
 682         float                  delta;
 683         float                  split_threshold;
 684
 685         (void) pref;
 686
 687         /* stupid hack: don't optimisticallt split don't spill nodes...
 688          * (so we don't split away the values produced because of
 689          *  must_be_different constraints) */
 690         original_insn = skip_Proj(info->original_value);
 691         if (arch_irn_get_flags(original_insn) & arch_irn_flags_dont_spill)
 692                 return false;
 693
 694         from_reg        = arch_get_irn_register(to_split);
 695         from_r          = arch_register_get_index(from_reg);
 696         block           = get_nodes_block(before);
 697         split_threshold = (float)get_block_execfreq(execfreqs, block) * SPLIT_DELTA;
 698
 699         if (pref_delta < split_threshold*0.5)
 700                 return false;
 701
 702         /* find the best free position where we could move to */
 703         prefs = ALLOCAN(reg_pref_t, n_regs);
 704         fill_sort_candidates(prefs, info);
 705         for (i = 0; i < n_regs; ++i) {
 706                 float apref;
 707                 float apref_delta;
 708                 bool  res;
 709                 bool  old_source_state;
 710
 711                 /* we need a normal register which is not an output register
 712                    an different from the current register of to_split */
 713                 r = prefs[i].num;
 714                 if (!rbitset_is_set(normal_regs, r))
 715                         continue;
 716                 if (rbitset_is_set(forbidden_regs, r))
 717                         continue;
 718                 if (r == from_r)
 719                         continue;
 720
 721                 /* is the split worth it? */
 722                 delta = pref_delta + prefs[i].pref;
 723                 if (delta < split_threshold) {
 724                         DB((dbg, LEVEL_3, "Not doing optimistical split of %+F (depth %d), win %f too low\n",
 725                                 to_split, recursion, delta));
 726                         return false;
 727                 }
 728
 729                 /* if the register is free then we can do the split */
 730                 if (assignments[r] == NULL)
 731                         break;
 732
 733                 /* otherwise we might try recursively calling optimistic_split */
 734                 if (recursion+1 > MAX_OPTIMISTIC_SPLIT_RECURSION)
 735                         continue;
 736
 737                 apref        = prefs[i].pref;
 738                 apref_delta  = i+1 < n_regs ? apref - prefs[i+1].pref : 0;
 739                 apref_delta += pref_delta - split_threshold;
 740
 741                 /* our source register isn't a useful destination for recursive
 742                    splits */
 743                 old_source_state = rbitset_is_set(forbidden_regs, from_r);
 744                 rbitset_set(forbidden_regs, from_r);
 745                 /* try recursive split */
 746                 res = try_optimistic_split(assignments[r], before, apref,
 747                                            apref_delta, forbidden_regs, recursion+1);
 748                 /* restore our destination */
 749                 if (old_source_state) {
 750                         rbitset_set(forbidden_regs, from_r);
 751                 } else {
 752                         rbitset_clear(forbidden_regs, from_r);
 753                 }
 754
 755                 if (res)
 756                         break;
 757         }
 758         if (i >= n_regs)
 759                 return false;
 760
 761         reg  = arch_register_for_index(cls, r);
 762         copy = be_new_Copy(cls, block, to_split);
 763         mark_as_copy_of(copy, to_split);
 764         /* hacky, but correct here */
 765         if (assignments[arch_register_get_index(from_reg)] == to_split)
 766                 free_reg_of_value(to_split);
 767         use_reg(copy, reg);
 768         sched_add_before(before, copy);
 769
 770         DB((dbg, LEVEL_3,
 771             "Optimistic live-range split %+F move %+F(%s) -> %s before %+F (win %f, depth %d)\n",
 772             copy, to_split, from_reg->name, reg->name, before, delta, recursion));
 773         return true;
 774 }
 775
 776 /**
 777  * Determine and assign a register for node @p node
 778  */
 779 static void assign_reg(const ir_node *block, ir_node *node,
 780                        unsigned *forbidden_regs)
 781 {
 782         const arch_register_t     *reg;
 783         allocation_info_t         *info;
 784         const arch_register_req_t *req;
 785         reg_pref_t                *reg_prefs;
 786         ir_node                   *in_node;
 787         unsigned                   i;
 788         const unsigned            *allowed_regs;
 789         unsigned                   r;
 790
 791         assert(!is_Phi(node));
 792         assert(arch_irn_consider_in_reg_alloc(cls, node));
 793
 794         /* preassigned register? */
 795         reg = arch_get_irn_register(node);
 796         if (reg != NULL) {
 797                 DB((dbg, LEVEL_2, "Preassignment %+F -> %s\n", node, reg->name));
 798                 use_reg(node, reg);
 799                 return;
 800         }
 801
 802         /* give should_be_same boni */
 803         info = get_allocation_info(node);
 804         req  = arch_get_register_req_out(node);
 805
 806         in_node = skip_Proj(node);
 807         if (req->type & arch_register_req_type_should_be_same) {
 808                 float weight = (float)get_block_execfreq(execfreqs, block);
 809                 int   arity  = get_irn_arity(in_node);
 810                 int   i;
 811
 812                 assert(arity <= (int) sizeof(req->other_same) * 8);
 813                 for (i = 0; i < arity; ++i) {
 814                         ir_node               *in;
 815                         const arch_register_t *reg;
 816                         unsigned               r;
 817                         if (!rbitset_is_set(&req->other_same, i))
 818                                 continue;
 819
 820                         in  = get_irn_n(in_node, i);
 821                         reg = arch_get_irn_register(in);
 822                         assert(reg != NULL);
 823                         r = arch_register_get_index(reg);
 824
 825                         /* if the value didn't die here then we should not propagate the
 826                          * should_be_same info */
 827                         if (assignments[r] == in)
 828                                 continue;
 829
 830                         info->prefs[r] += weight * AFF_SHOULD_BE_SAME;
 831                 }
 832         }
 833
 834         /* create list of register candidates and sort by their preference */
 835         DB((dbg, LEVEL_2, "Candidates for %+F:", node));
 836         reg_prefs = alloca(n_regs * sizeof(reg_prefs[0]));
 837         fill_sort_candidates(reg_prefs, info);
 838         for (i = 0; i < n_regs; ++i) {
 839                 unsigned num = reg_prefs[i].num;
 840                 const arch_register_t *reg;
 841
 842                 if (!rbitset_is_set(normal_regs, num))
 843                         continue;
 844
 845                 reg = arch_register_for_index(cls, num);
 846                 DB((dbg, LEVEL_2, " %s(%f)", reg->name, reg_prefs[i].pref));
 847         }
 848         DB((dbg, LEVEL_2, "\n"));
 849
 850         allowed_regs = normal_regs;
 851         if (req->type & arch_register_req_type_limited) {
 852                 allowed_regs = req->limited;
 853         }
 854
 855         for (i = 0; i < n_regs; ++i) {
 856                 float   pref, delta;
 857                 ir_node *before;
 858                 bool    res;
 859
 860                 r = reg_prefs[i].num;
 861                 if (!rbitset_is_set(allowed_regs, r))
 862                         continue;
 863                 if (assignments[r] == NULL)
 864                         break;
 865                 pref   = reg_prefs[i].pref;
 866                 delta  = i+1 < n_regs ? pref - reg_prefs[i+1].pref : 0;
 867                 before = skip_Proj(node);
 868                 res    = try_optimistic_split(assignments[r], before,
 869                                               pref, delta, forbidden_regs, 0);
 870                 if (res)
 871                         break;
 872         }
 873         if (i >= n_regs) {
 874                 panic("No register left for %+F\n", node);
 875         }
 876
 877         reg = arch_register_for_index(cls, r);
 878         DB((dbg, LEVEL_2, "Assign %+F -> %s\n", node, reg->name));
 879         use_reg(node, reg);
 880 }
 881
 882 /**
 883  * Add an permutation in front of a node and change the assignments
 884  * due to this permutation.
 885  *
 886  * To understand this imagine a permutation like this:
 887  *
 888  * 1 -> 2
 889  * 2 -> 3
 890  * 3 -> 1, 5
 891  * 4 -> 6
 892  * 5
 893  * 6
 894  * 7 -> 7
 895  *
 896  * First we count how many destinations a single value has. At the same time
 897  * we can be sure that each destination register has at most 1 source register
 898  * (it can have 0 which means we don't care what value is in it).
 899  * We ignore all fullfilled permuations (like 7->7)
 900  * In a first pass we create as much copy instructions as possible as they
 901  * are generally cheaper than exchanges. We do this by counting into how many
 902  * destinations a register has to be copied (in the example it's 2 for register
 903  * 3, or 1 for the registers 1,2,4 and 7).
 904  * We can then create a copy into every destination register when the usecount
 905  * of that register is 0 (= noone else needs the value in the register).
 906  *
 907  * After this step we should have cycles left. We implement a cyclic permutation
 908  * of n registers with n-1 transpositions.
 909  *
 910  * @param live_nodes   the set of live nodes, updated due to live range split
 911  * @param before       the node before we add the permutation
 912  * @param permutation  the permutation array indices are the destination
 913  *                     registers, the values in the array are the source
 914  *                     registers.
 915  */
 916 static void permute_values(ir_nodeset_t *live_nodes, ir_node *before,
 917                              unsigned *permutation)
 918 {
 919         unsigned  *n_used = ALLOCANZ(unsigned, n_regs);
 920         ir_node   *block;
 921         unsigned   r;
 922
 923         /* determine how often each source register needs to be read */
 924         for (r = 0; r < n_regs; ++r) {
 925                 unsigned  old_reg = permutation[r];
 926                 ir_node  *value;
 927
 928                 value = assignments[old_reg];
 929                 if (value == NULL) {
 930                         /* nothing to do here, reg is not live. Mark it as fixpoint
 931                          * so we ignore it in the next steps */
 932                         permutation[r] = r;
 933                         continue;
 934                 }
 935
 936                 ++n_used[old_reg];
 937         }
 938
 939         block = get_nodes_block(before);
 940
 941         /* step1: create copies where immediately possible */
 942         for (r = 0; r < n_regs; /* empty */) {
 943                 ir_node *copy;
 944                 ir_node *src;
 945                 const arch_register_t *reg;
 946                 unsigned               old_r = permutation[r];
 947
 948                 /* - no need to do anything for fixed points.
 949                    - we can't copy if the value in the dest reg is still needed */
 950                 if (old_r == r || n_used[r] > 0) {
 951                         ++r;
 952                         continue;
 953                 }
 954
 955                 /* create a copy */
 956                 src  = assignments[old_r];
 957                 copy = be_new_Copy(cls, block, src);
 958                 sched_add_before(before, copy);
 959                 reg = arch_register_for_index(cls, r);
 960                 DB((dbg, LEVEL_2, "Copy %+F (from %+F, before %+F) -> %s\n",
 961                     copy, src, before, reg->name));
 962                 mark_as_copy_of(copy, src);
 963                 use_reg(copy, reg);
 964
 965                 if (live_nodes != NULL) {
 966                         ir_nodeset_insert(live_nodes, copy);
 967                 }
 968
 969                 /* old register has 1 user less, permutation is resolved */
 970                 assert(arch_register_get_index(arch_get_irn_register(src)) == old_r);
 971                 permutation[r] = r;
 972
 973                 assert(n_used[old_r] > 0);
 974                 --n_used[old_r];
 975                 if (n_used[old_r] == 0) {
 976                         if (live_nodes != NULL) {
 977                                 ir_nodeset_remove(live_nodes, src);
 978                         }
 979                         free_reg_of_value(src);
 980                 }
 981
 982                 /* advance or jump back (if this copy enabled another copy) */
 983                 if (old_r < r && n_used[old_r] == 0) {
 984                         r = old_r;
 985                 } else {
 986                         ++r;
 987                 }
 988         }
 989
 990         /* at this point we only have "cycles" left which we have to resolve with
 991          * perm instructions
 992          * TODO: if we have free registers left, then we should really use copy
 993          * instructions for any cycle longer than 2 registers...
 994          * (this is probably architecture dependent, there might be archs where
 995          *  copies are preferable even for 2-cycles) */
 996
 997         /* create perms with the rest */
 998         for (r = 0; r < n_regs; /* empty */) {
 999                 const arch_register_t *reg;
1000                 unsigned  old_r = permutation[r];
1001                 unsigned  r2;
1002                 ir_node  *in[2];
1003                 ir_node  *perm;
1004                 ir_node  *proj0;
1005                 ir_node  *proj1;
1006
1007                 if (old_r == r) {
1008                         ++r;
1009                         continue;
1010                 }
1011
1012                 /* we shouldn't have copies from 1 value to multiple destinations left*/
1013                 assert(n_used[old_r] == 1);
1014
1015                 /* exchange old_r and r2; after that old_r is a fixed point */
1016                 r2 = permutation[old_r];
1017
1018                 in[0] = assignments[r2];
1019                 in[1] = assignments[old_r];
1020                 perm = be_new_Perm(cls, block, 2, in);
1021                 sched_add_before(before, perm);
1022                 DB((dbg, LEVEL_2, "Perm %+F (perm %+F,%+F, before %+F)\n",
1023                     perm, in[0], in[1], before));
1024
1025                 proj0 = new_r_Proj(perm, get_irn_mode(in[0]), 0);
1026                 mark_as_copy_of(proj0, in[0]);
1027                 reg = arch_register_for_index(cls, old_r);
1028                 use_reg(proj0, reg);
1029
1030                 proj1 = new_r_Proj(perm, get_irn_mode(in[1]), 1);
1031                 mark_as_copy_of(proj1, in[1]);
1032                 reg = arch_register_for_index(cls, r2);
1033                 use_reg(proj1, reg);
1034
1035                 /* 1 value is now in the correct register */
1036                 permutation[old_r] = old_r;
1037                 /* the source of r changed to r2 */
1038                 permutation[r] = r2;
1039
1040                 /* if we have reached a fixpoint update data structures */
1041                 if (live_nodes != NULL) {
1042                         ir_nodeset_remove(live_nodes, in[0]);
1043                         ir_nodeset_remove(live_nodes, in[1]);
1044                         ir_nodeset_remove(live_nodes, proj0);
1045                         ir_nodeset_insert(live_nodes, proj1);
1046                 }
1047         }
1048
1049 #ifdef DEBUG_libfirm
1050         /* now we should only have fixpoints left */
1051         for (r = 0; r < n_regs; ++r) {
1052                 assert(permutation[r] == r);
1053         }
1054 #endif
1055 }
1056
1057 /**
1058  * Free regs for values last used.
1059  *
1060  * @param live_nodes   set of live nodes, will be updated
1061  * @param node         the node to consider
1062  */
1063 static void free_last_uses(ir_nodeset_t *live_nodes, ir_node *node)
1064 {
1065         allocation_info_t     *info      = get_allocation_info(node);
1066         const unsigned        *last_uses = &info->last_uses;
1067         int                    arity     = get_irn_arity(node);
1068         int                    i;
1069
1070         for (i = 0; i < arity; ++i) {
1071                 ir_node *op;
1072
1073                 /* check if one operand is the last use */
1074                 if (!rbitset_is_set(last_uses, i))
1075                         continue;
1076
1077                 op = get_irn_n(node, i);
1078                 free_reg_of_value(op);
1079                 ir_nodeset_remove(live_nodes, op);
1080         }
1081 }
1082
1083 /**
1084  * change inputs of a node to the current value (copies/perms)
1085  */
1086 static void rewire_inputs(ir_node *node)
1087 {
1088         int i;
1089         int arity = get_irn_arity(node);
1090
1091         for (i = 0; i < arity; ++i) {
1092                 ir_node           *op = get_irn_n(node, i);
1093                 allocation_info_t *info = try_get_allocation_info(op);
1094
1095                 if (info == NULL)
1096                         continue;
1097
1098                 info = get_allocation_info(info->original_value);
1099                 if (info->current_value != op) {
1100                         set_irn_n(node, i, info->current_value);
1101                 }
1102         }
1103 }
1104
1105 /**
1106  * Create a bitset of registers occupied with value living through an
1107  * instruction
1108  */
1109 static void determine_live_through_regs(unsigned *bitset, ir_node *node)
1110 {
1111         const allocation_info_t *info = get_allocation_info(node);
1112         unsigned r;
1113         int i;
1114         int arity;
1115
1116         /* mark all used registers as potentially live-through */
1117         for (r = 0; r < n_regs; ++r) {
1118                 if (assignments[r] == NULL)
1119                         continue;
1120                 if (!rbitset_is_set(normal_regs, r))
1121                         continue;
1122
1123                 rbitset_set(bitset, r);
1124         }
1125
1126         /* remove registers of value dying at the instruction */
1127         arity = get_irn_arity(node);
1128         for (i = 0; i < arity; ++i) {
1129                 ir_node               *op;
1130                 const arch_register_t *reg;
1131
1132                 if (!rbitset_is_set(&info->last_uses, i))
1133                         continue;
1134
1135                 op  = get_irn_n(node, i);
1136                 reg = arch_get_irn_register(op);
1137                 rbitset_clear(bitset, arch_register_get_index(reg));
1138         }
1139 }
1140
1141 /**
1142  * Enforce constraints at a node by live range splits.
1143  *
1144  * @param  live_nodes  the set of live nodes, might be changed
1145  * @param  node        the current node
1146  */
1147 static void enforce_constraints(ir_nodeset_t *live_nodes, ir_node *node,
1148                                 unsigned *forbidden_regs)
1149 {
1150         int arity = get_irn_arity(node);
1151         int i, res;
1152         hungarian_problem_t *bp;
1153         unsigned l, r;
1154         unsigned *assignment;
1155
1156         /* construct a list of register occupied by live-through values */
1157         unsigned *live_through_regs = NULL;
1158
1159         /* see if any use constraints are not met */
1160         bool good = true;
1161         for (i = 0; i < arity; ++i) {
1162                 ir_node                   *op = get_irn_n(node, i);
1163                 const arch_register_t     *reg;
1164                 const arch_register_req_t *req;
1165                 const unsigned            *limited;
1166                 unsigned                  r;
1167
1168                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1169                         continue;
1170
1171                 /* are there any limitations for the i'th operand? */
1172                 req = arch_get_register_req(node, i);
1173                 if (!(req->type & arch_register_req_type_limited))
1174                         continue;
1175
1176                 limited = req->limited;
1177                 reg     = arch_get_irn_register(op);
1178                 r       = arch_register_get_index(reg);
1179                 if (!rbitset_is_set(limited, r)) {
1180                         /* found an assignment outside the limited set */
1181                         good = false;
1182                         break;
1183                 }
1184         }
1185
1186         /* is any of the live-throughs using a constrained output register? */
1187         if (get_irn_mode(node) == mode_T) {
1188                 const ir_edge_t *edge;
1189
1190                 foreach_out_edge(node, edge) {
1191                         ir_node *proj = get_edge_src_irn(edge);
1192                         const arch_register_req_t *req;
1193
1194                         if (!arch_irn_consider_in_reg_alloc(cls, proj))
1195                                 continue;
1196
1197                         req = arch_get_register_req_out(proj);
1198                         if (!(req->type & arch_register_req_type_limited))
1199                                 continue;
1200
1201                         if (live_through_regs == NULL) {
1202                                 rbitset_alloca(live_through_regs, n_regs);
1203                                 determine_live_through_regs(live_through_regs, node);
1204                         }
1205
1206                         rbitset_or(forbidden_regs, req->limited, n_regs);
1207                         if (rbitsets_have_common(req->limited, live_through_regs, n_regs)) {
1208                                 good = false;
1209                         }
1210                 }
1211         } else {
1212                 if (arch_irn_consider_in_reg_alloc(cls, node)) {
1213                         const arch_register_req_t *req = arch_get_register_req_out(node);
1214                         if (req->type & arch_register_req_type_limited) {
1215                                 rbitset_alloca(live_through_regs, n_regs);
1216                                 determine_live_through_regs(live_through_regs, node);
1217                                 if (rbitsets_have_common(req->limited, live_through_regs, n_regs)) {
1218                                         good = false;
1219                                         rbitset_or(forbidden_regs, req->limited, n_regs);
1220                                 }
1221                         }
1222                 }
1223         }
1224
1225         if (good)
1226                 return;
1227
1228         /* create these arrays if we haven't yet */
1229         if (live_through_regs == NULL) {
1230                 rbitset_alloca(live_through_regs, n_regs);
1231         }
1232
1233         /* at this point we have to construct a bipartite matching problem to see
1234          * which values should go to which registers
1235          * Note: We're building the matrix in "reverse" - source registers are
1236          *       right, destinations left because this will produce the solution
1237          *       in the format required for permute_values.
1238          */
1239         bp = hungarian_new(n_regs, n_regs, HUNGARIAN_MATCH_PERFECT);
1240
1241         /* add all combinations, then remove not allowed ones */
1242         for (l = 0; l < n_regs; ++l) {
1243                 if (!rbitset_is_set(normal_regs, l)) {
1244                         hungarian_add(bp, l, l, 1);
1245                         continue;
1246                 }
1247
1248                 for (r = 0; r < n_regs; ++r) {
1249                         if (!rbitset_is_set(normal_regs, r))
1250                                 continue;
1251                         /* livethrough values may not use constrainted output registers */
1252                         if (rbitset_is_set(live_through_regs, l)
1253                                         && rbitset_is_set(forbidden_regs, r))
1254                                 continue;
1255
1256                         hungarian_add(bp, r, l, l == r ? 9 : 8);
1257                 }
1258         }
1259
1260         for (i = 0; i < arity; ++i) {
1261                 ir_node                   *op = get_irn_n(node, i);
1262                 const arch_register_t     *reg;
1263                 const arch_register_req_t *req;
1264                 const unsigned            *limited;
1265                 unsigned                   current_reg;
1266
1267                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1268                         continue;
1269
1270                 req = arch_get_register_req(node, i);
1271                 if (!(req->type & arch_register_req_type_limited))
1272                         continue;
1273
1274                 limited     = req->limited;
1275                 reg         = arch_get_irn_register(op);
1276                 current_reg = arch_register_get_index(reg);
1277                 for (r = 0; r < n_regs; ++r) {
1278                         if (rbitset_is_set(limited, r))
1279                                 continue;
1280                         hungarian_remv(bp, r, current_reg);
1281                 }
1282         }
1283
1284         //hungarian_print_cost_matrix(bp, 1);
1285         hungarian_prepare_cost_matrix(bp, HUNGARIAN_MODE_MAXIMIZE_UTIL);
1286
1287         assignment = ALLOCAN(unsigned, n_regs);
1288         res = hungarian_solve(bp, (int*) assignment, NULL, 0);
1289         assert(res == 0);
1290
1291 #if 0
1292         fprintf(stderr, "Swap result:");
1293         for (i = 0; i < (int) n_regs; ++i) {
1294                 fprintf(stderr, " %d", assignment[i]);
1295         }
1296         fprintf(stderr, "\n");
1297 #endif
1298
1299         hungarian_free(bp);
1300
1301         permute_values(live_nodes, node, assignment);
1302 }
1303
1304 /** test wether a node @p n is a copy of the value of node @p of */
1305 static bool is_copy_of(ir_node *value, ir_node *test_value)
1306 {
1307         allocation_info_t *test_info;
1308         allocation_info_t *info;
1309
1310         if (value == test_value)
1311                 return true;
1312
1313         info      = get_allocation_info(value);
1314         test_info = get_allocation_info(test_value);
1315         return test_info->original_value == info->original_value;
1316 }
1317
1318 /**
1319  * find a value in the end-assignment of a basic block
1320  * @returns the index into the assignment array if found
1321  *          -1 if not found
1322  */
1323 static int find_value_in_block_info(block_info_t *info, ir_node *value)
1324 {
1325         unsigned   r;
1326         ir_node  **assignments = info->assignments;
1327         for (r = 0; r < n_regs; ++r) {
1328                 ir_node *a_value = assignments[r];
1329
1330                 if (a_value == NULL)
1331                         continue;
1332                 if (is_copy_of(a_value, value))
1333                         return (int) r;
1334         }
1335
1336         return -1;
1337 }
1338
1339 /**
1340  * Create the necessary permutations at the end of a basic block to fullfill
1341  * the register assignment for phi-nodes in the next block
1342  */
1343 static void add_phi_permutations(ir_node *block, int p)
1344 {
1345         unsigned   r;
1346         unsigned  *permutation;
1347         ir_node  **old_assignments;
1348         bool       need_permutation;
1349         ir_node   *node;
1350         ir_node   *pred = get_Block_cfgpred_block(block, p);
1351
1352         block_info_t *pred_info = get_block_info(pred);
1353
1354         /* predecessor not processed yet? nothing to do */
1355         if (!pred_info->processed)
1356                 return;
1357
1358         permutation = ALLOCAN(unsigned, n_regs);
1359         for (r = 0; r < n_regs; ++r) {
1360                 permutation[r] = r;
1361         }
1362
1363         /* check phi nodes */
1364         need_permutation = false;
1365         node = sched_first(block);
1366         for ( ; is_Phi(node); node = sched_next(node)) {
1367                 const arch_register_t *reg;
1368                 int                    regn;
1369                 int                    a;
1370                 ir_node               *op;
1371
1372                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1373                         continue;
1374
1375                 op = get_Phi_pred(node, p);
1376                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1377                         continue;
1378
1379                 a = find_value_in_block_info(pred_info, op);
1380                 assert(a >= 0);
1381
1382                 reg  = arch_get_irn_register(node);
1383                 regn = arch_register_get_index(reg);
1384                 if (regn != a) {
1385                         permutation[regn] = a;
1386                         need_permutation  = true;
1387                 }
1388         }
1389
1390         if (need_permutation) {
1391                 /* permute values at end of predecessor */
1392                 old_assignments = assignments;
1393                 assignments     = pred_info->assignments;
1394                 permute_values(NULL, be_get_end_of_block_insertion_point(pred),
1395                                                  permutation);
1396                 assignments = old_assignments;
1397         }
1398
1399         /* change phi nodes to use the copied values */
1400         node = sched_first(block);
1401         for ( ; is_Phi(node); node = sched_next(node)) {
1402                 int      a;
1403                 ir_node *op;
1404
1405                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1406                         continue;
1407
1408                 op = get_Phi_pred(node, p);
1409                 /* no need to do anything for Unknown inputs */
1410                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1411                         continue;
1412
1413                 /* we have permuted all values into the correct registers so we can
1414                    simply query which value occupies the phis register in the
1415                    predecessor */
1416                 a  = arch_register_get_index(arch_get_irn_register(node));
1417                 op = pred_info->assignments[a];
1418                 set_Phi_pred(node, p, op);
1419         }
1420 }
1421
1422 /**
1423  * Set preferences for a phis register based on the registers used on the
1424  * phi inputs.
1425  */
1426 static void adapt_phi_prefs(ir_node *phi)
1427 {
1428         int i;
1429         int arity = get_irn_arity(phi);
1430         ir_node           *block = get_nodes_block(phi);
1431         allocation_info_t *info  = get_allocation_info(phi);
1432
1433         for (i = 0; i < arity; ++i) {
1434                 ir_node               *op  = get_irn_n(phi, i);
1435                 const arch_register_t *reg = arch_get_irn_register(op);
1436                 ir_node               *pred_block;
1437                 block_info_t          *pred_block_info;
1438                 float                  weight;
1439                 unsigned               r;
1440
1441                 if (reg == NULL)
1442                         continue;
1443                 /* we only give the bonus if the predecessor already has registers
1444                  * assigned, otherwise we only see a dummy value
1445                  * and any conclusions about its register are useless */
1446                 pred_block = get_Block_cfgpred_block(block, i);
1447                 pred_block_info = get_block_info(pred_block);
1448                 if (!pred_block_info->processed)
1449                         continue;
1450
1451                 /* give bonus for already assigned register */
1452                 weight = (float)get_block_execfreq(execfreqs, pred_block);
1453                 r      = arch_register_get_index(reg);
1454                 info->prefs[r] += weight * AFF_PHI;
1455         }
1456 }
1457
1458 /**
1459  * After a phi has been assigned a register propagate preference inputs
1460  * to the phi inputs.
1461  */
1462 static void propagate_phi_register(ir_node *phi, unsigned assigned_r)
1463 {
1464         int      i;
1465         ir_node *block = get_nodes_block(phi);
1466         int      arity = get_irn_arity(phi);
1467
1468         for (i = 0; i < arity; ++i) {
1469                 ir_node           *op         = get_Phi_pred(phi, i);
1470                 allocation_info_t *info       = get_allocation_info(op);
1471                 ir_node           *pred_block = get_Block_cfgpred_block(block, i);
1472                 unsigned           r;
1473                 float              weight
1474                         = (float)get_block_execfreq(execfreqs, pred_block) * AFF_PHI;
1475
1476                 if (info->prefs[assigned_r] >= weight)
1477                         continue;
1478
1479                 /* promote the prefered register */
1480                 for (r = 0; r < n_regs; ++r) {
1481                         if (info->prefs[r] > -weight) {
1482                                 info->prefs[r] = -weight;
1483                         }
1484                 }
1485                 info->prefs[assigned_r] = weight;
1486
1487                 if (is_Phi(op))
1488                         propagate_phi_register(op, assigned_r);
1489         }
1490 }
1491
1492 static void assign_phi_registers(ir_node *block)
1493 {
1494         int                  n_phis = 0;
1495         int                  n;
1496         int                  res;
1497         int                 *assignment;
1498         ir_node             *node;
1499         hungarian_problem_t *bp;
1500
1501         /* count phi nodes */
1502         sched_foreach(block, node) {
1503                 if (!is_Phi(node))
1504                         break;
1505                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1506                         continue;
1507                 ++n_phis;
1508         }
1509
1510         if (n_phis == 0)
1511                 return;
1512
1513         /* build a bipartite matching problem for all phi nodes */
1514         bp = hungarian_new(n_phis, n_regs, HUNGARIAN_MATCH_PERFECT);
1515         n  = 0;
1516         sched_foreach(block, node) {
1517                 unsigned r;
1518
1519                 allocation_info_t *info;
1520                 if (!is_Phi(node))
1521                         break;
1522                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1523                         continue;
1524
1525                 /* give boni for predecessor colorings */
1526                 adapt_phi_prefs(node);
1527                 /* add stuff to bipartite problem */
1528                 info = get_allocation_info(node);
1529                 DB((dbg, LEVEL_3, "Prefs for %+F: ", node));
1530                 for (r = 0; r < n_regs; ++r) {
1531                         float costs;
1532
1533                         if (!rbitset_is_set(normal_regs, r))
1534                                 continue;
1535
1536                         costs = info->prefs[r];
1537                         costs = costs < 0 ? -logf(-costs+1) : logf(costs+1);
1538                         costs *= 100;
1539                         costs += 10000;
1540                         hungarian_add(bp, n, r, (int)costs);
1541                         DB((dbg, LEVEL_3, " %s(%f)", arch_register_for_index(cls, r)->name,
1542                                                 info->prefs[r]));
1543                 }
1544                 DB((dbg, LEVEL_3, "\n"));
1545                 ++n;
1546         }
1547
1548         //hungarian_print_cost_matrix(bp, 7);
1549         hungarian_prepare_cost_matrix(bp, HUNGARIAN_MODE_MAXIMIZE_UTIL);
1550
1551         assignment = ALLOCAN(int, n_regs);
1552         res        = hungarian_solve(bp, assignment, NULL, 0);
1553         assert(res == 0);
1554
1555         /* apply results */
1556         n = 0;
1557         sched_foreach(block, node) {
1558                 unsigned               r;
1559                 const arch_register_t *reg;
1560
1561                 if (!is_Phi(node))
1562                         break;
1563                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1564                         continue;
1565
1566                 r   = assignment[n++];
1567                 assert(rbitset_is_set(normal_regs, r));
1568                 reg = arch_register_for_index(cls, r);
1569                 DB((dbg, LEVEL_2, "Assign %+F -> %s\n", node, reg->name));
1570                 use_reg(node, reg);
1571
1572                 /* adapt preferences for phi inputs */
1573                 if (propagate_phi_registers)
1574                         propagate_phi_register(node, r);
1575         }
1576 }
1577
1578 /**
1579  * Walker: assign registers to all nodes of a block that
1580  * need registers from the currently considered register class.
1581  */
1582 static void allocate_coalesce_block(ir_node *block, void *data)
1583 {
1584         int                    i;
1585         ir_nodeset_t           live_nodes;
1586         ir_node               *node;
1587         int                    n_preds;
1588         block_info_t          *block_info;
1589         block_info_t         **pred_block_infos;
1590         ir_node              **phi_ins;
1591         unsigned              *forbidden_regs; /**< collects registers which must
1592                                                 not be used for optimistic splits */
1593
1594         (void) data;
1595         DB((dbg, LEVEL_2, "* Block %+F\n", block));
1596
1597         /* clear assignments */
1598         block_info  = get_block_info(block);
1599         assignments = block_info->assignments;
1600
1601         ir_nodeset_init(&live_nodes);
1602
1603         /* gather regalloc infos of predecessor blocks */
1604         n_preds             = get_Block_n_cfgpreds(block);
1605         pred_block_infos    = ALLOCAN(block_info_t*, n_preds);
1606         for (i = 0; i < n_preds; ++i) {
1607                 ir_node      *pred      = get_Block_cfgpred_block(block, i);
1608                 block_info_t *pred_info = get_block_info(pred);
1609                 pred_block_infos[i]     = pred_info;
1610         }
1611
1612         phi_ins = ALLOCAN(ir_node*, n_preds);
1613
1614         /* collect live-in nodes and preassigned values */
1615         be_lv_foreach(lv, block, be_lv_state_in, i) {
1616                 const arch_register_t *reg;
1617                 int                    p;
1618                 bool                   need_phi = false;
1619
1620                 node = be_lv_get_irn(lv, block, i);
1621                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1622                         continue;
1623
1624                 /* check all predecessors for this value, if it is not everywhere the
1625                    same or unknown then we have to construct a phi
1626                    (we collect the potential phi inputs here) */
1627                 for (p = 0; p < n_preds; ++p) {
1628                         block_info_t *pred_info = pred_block_infos[p];
1629
1630                         if (!pred_info->processed) {
1631                                 /* use node for now, it will get fixed later */
1632                                 phi_ins[p] = node;
1633                                 need_phi   = true;
1634                         } else {
1635                                 int a = find_value_in_block_info(pred_info, node);
1636
1637                                 /* must live out of predecessor */
1638                                 assert(a >= 0);
1639                                 phi_ins[p] = pred_info->assignments[a];
1640                                 /* different value from last time? then we need a phi */
1641                                 if (p > 0 && phi_ins[p-1] != phi_ins[p]) {
1642                                         need_phi = true;
1643                                 }
1644                         }
1645                 }
1646
1647                 if (need_phi) {
1648                         ir_mode                   *mode = get_irn_mode(node);
1649                         const arch_register_req_t *req  = get_default_req_current_cls();
1650                         ir_node                   *phi;
1651
1652                         phi = new_r_Phi(block, n_preds, phi_ins, mode);
1653                         be_set_phi_reg_req(phi, req);
1654
1655                         DB((dbg, LEVEL_3, "Create Phi %+F (for %+F) -", phi, node));
1656 #ifdef DEBUG_libfirm
1657                         {
1658                                 int i;
1659                                 for (i = 0; i < n_preds; ++i) {
1660                                         DB((dbg, LEVEL_3, " %+F", phi_ins[i]));
1661                                 }
1662                                 DB((dbg, LEVEL_3, "\n"));
1663                         }
1664 #endif
1665                         mark_as_copy_of(phi, node);
1666                         sched_add_after(block, phi);
1667
1668                         node = phi;
1669                 } else {
1670                         allocation_info_t *info = get_allocation_info(node);
1671                         info->current_value = phi_ins[0];
1672
1673                         /* Grab 1 of the inputs we constructed (might not be the same as
1674                          * "node" as we could see the same copy of the value in all
1675                          * predecessors */
1676                         node = phi_ins[0];
1677                 }
1678
1679                 /* if the node already has a register assigned use it */
1680                 reg = arch_get_irn_register(node);
1681                 if (reg != NULL) {
1682                         use_reg(node, reg);
1683                 }
1684
1685                 /* remember that this node is live at the beginning of the block */
1686                 ir_nodeset_insert(&live_nodes, node);
1687         }
1688
1689         rbitset_alloca(forbidden_regs, n_regs);
1690
1691         /* handle phis... */
1692         assign_phi_registers(block);
1693
1694         /* all live-ins must have a register */
1695 #ifdef DEBUG_libfirm
1696         {
1697                 ir_nodeset_iterator_t  iter;
1698                 foreach_ir_nodeset(&live_nodes, node, iter) {
1699                         const arch_register_t *reg = arch_get_irn_register(node);
1700                         assert(reg != NULL);
1701                 }
1702         }
1703 #endif
1704
1705         /* assign instructions in the block */
1706         sched_foreach(block, node) {
1707                 int i;
1708                 int arity;
1709
1710                 /* phis are already assigned */
1711                 if (is_Phi(node))
1712                         continue;
1713
1714                 rewire_inputs(node);
1715
1716                 /* enforce use constraints */
1717                 rbitset_clear_all(forbidden_regs, n_regs);
1718                 enforce_constraints(&live_nodes, node, forbidden_regs);
1719
1720                 rewire_inputs(node);
1721
1722                 /* we may not use registers used for inputs for optimistic splits */
1723                 arity = get_irn_arity(node);
1724                 for (i = 0; i < arity; ++i) {
1725                         ir_node *op = get_irn_n(node, i);
1726                         const arch_register_t *reg;
1727                         if (!arch_irn_consider_in_reg_alloc(cls, op))
1728                                 continue;
1729
1730                         reg = arch_get_irn_register(op);
1731                         rbitset_set(forbidden_regs, arch_register_get_index(reg));
1732                 }
1733
1734                 /* free registers of values last used at this instruction */
1735                 free_last_uses(&live_nodes, node);
1736
1737                 /* assign output registers */
1738                 /* TODO: 2 phases: first: pre-assigned ones, 2nd real regs */
1739                 if (get_irn_mode(node) == mode_T) {
1740                         const ir_edge_t *edge;
1741                         foreach_out_edge(node, edge) {
1742                                 ir_node *proj = get_edge_src_irn(edge);
1743                                 if (!arch_irn_consider_in_reg_alloc(cls, proj))
1744                                         continue;
1745                                 assign_reg(block, proj, forbidden_regs);
1746                         }
1747                 } else if (arch_irn_consider_in_reg_alloc(cls, node)) {
1748                         assign_reg(block, node, forbidden_regs);
1749                 }
1750         }
1751
1752         ir_nodeset_destroy(&live_nodes);
1753         assignments = NULL;
1754
1755         block_info->processed = true;
1756
1757         /* permute values at end of predecessor blocks in case of phi-nodes */
1758         if (n_preds > 1) {
1759                 int p;
1760                 for (p = 0; p < n_preds; ++p) {
1761                         add_phi_permutations(block, p);
1762                 }
1763         }
1764
1765         /* if we have exactly 1 successor then we might be able to produce phi
1766            copies now */
1767         if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) == 1) {
1768                 const ir_edge_t *edge
1769                         = get_irn_out_edge_first_kind(block, EDGE_KIND_BLOCK);
1770                 ir_node      *succ      = get_edge_src_irn(edge);
1771                 int           p         = get_edge_src_pos(edge);
1772                 block_info_t *succ_info = get_block_info(succ);
1773
1774                 if (succ_info->processed) {
1775                         add_phi_permutations(succ, p);
1776                 }
1777         }
1778 }
1779
1780 typedef struct block_costs_t block_costs_t;
1781 struct block_costs_t {
1782         float costs;   /**< costs of the block */
1783         int   dfs_num; /**< depth first search number (to detect backedges) */
1784 };
1785
1786 static int cmp_block_costs(const void *d1, const void *d2)
1787 {
1788         const ir_node       * const *block1 = d1;
1789         const ir_node       * const *block2 = d2;
1790         const block_costs_t *info1  = get_irn_link(*block1);
1791         const block_costs_t *info2  = get_irn_link(*block2);
1792         return QSORT_CMP(info2->costs, info1->costs);
1793 }
1794
1795 static void determine_block_order(void)
1796 {
1797         int i;
1798         ir_node **blocklist = be_get_cfgpostorder(irg);
1799         int       n_blocks  = ARR_LEN(blocklist);
1800         int       dfs_num   = 0;
1801         pdeq     *worklist  = new_pdeq();
1802         ir_node **order     = XMALLOCN(ir_node*, n_blocks);
1803         int       order_p   = 0;
1804
1805         /* clear block links... */
1806         for (i = 0; i < n_blocks; ++i) {
1807                 ir_node *block = blocklist[i];
1808                 set_irn_link(block, NULL);
1809         }
1810
1811         /* walk blocks in reverse postorder, the costs for each block are the
1812          * sum of the costs of its predecessors (excluding the costs on backedges
1813          * which we can't determine) */
1814         for (i = n_blocks-1; i >= 0; --i) {
1815                 block_costs_t *cost_info;
1816                 ir_node *block = blocklist[i];
1817
1818                 float execfreq   = (float)get_block_execfreq(execfreqs, block);
1819                 float costs      = execfreq;
1820                 int   n_cfgpreds = get_Block_n_cfgpreds(block);
1821                 int   p;
1822                 for (p = 0; p < n_cfgpreds; ++p) {
1823                         ir_node       *pred_block = get_Block_cfgpred_block(block, p);
1824                         block_costs_t *pred_costs = get_irn_link(pred_block);
1825                         /* we don't have any info for backedges */
1826                         if (pred_costs == NULL)
1827                                 continue;
1828                         costs += pred_costs->costs;
1829                 }
1830
1831                 cost_info          = OALLOCZ(&obst, block_costs_t);
1832                 cost_info->costs   = costs;
1833                 cost_info->dfs_num = dfs_num++;
1834                 set_irn_link(block, cost_info);
1835         }
1836
1837         /* sort array by block costs */
1838         qsort(blocklist, n_blocks, sizeof(blocklist[0]), cmp_block_costs);
1839
1840         ir_reserve_resources(irg, IR_RESOURCE_BLOCK_VISITED);
1841         inc_irg_block_visited(irg);
1842
1843         for (i = 0; i < n_blocks; ++i) {
1844                 ir_node       *block = blocklist[i];
1845                 if (Block_block_visited(block))
1846                         continue;
1847
1848                 /* continually add predecessors with highest costs to worklist
1849                  * (without using backedges) */
1850                 do {
1851                         block_costs_t *info       = get_irn_link(block);
1852                         ir_node       *best_pred  = NULL;
1853                         float          best_costs = -1;
1854                         int            n_cfgpred  = get_Block_n_cfgpreds(block);
1855                         int            i;
1856
1857                         pdeq_putr(worklist, block);
1858                         mark_Block_block_visited(block);
1859                         for (i = 0; i < n_cfgpred; ++i) {
1860                                 ir_node       *pred_block = get_Block_cfgpred_block(block, i);
1861                                 block_costs_t *pred_info  = get_irn_link(pred_block);
1862
1863                                 /* ignore backedges */
1864                                 if (pred_info->dfs_num > info->dfs_num)
1865                                         continue;
1866
1867                                 if (info->costs > best_costs) {
1868                                         best_costs = info->costs;
1869                                         best_pred  = pred_block;
1870                                 }
1871                         }
1872                         block = best_pred;
1873                 } while (block != NULL && !Block_block_visited(block));
1874
1875                 /* now put all nodes in the worklist in our final order */
1876                 while (!pdeq_empty(worklist)) {
1877                         ir_node *pblock = pdeq_getr(worklist);
1878                         assert(order_p < n_blocks);
1879                         order[order_p++] = pblock;
1880                 }
1881         }
1882         assert(order_p == n_blocks);
1883         del_pdeq(worklist);
1884
1885         ir_free_resources(irg, IR_RESOURCE_BLOCK_VISITED);
1886
1887         DEL_ARR_F(blocklist);
1888
1889         obstack_free(&obst, NULL);
1890         obstack_init(&obst);
1891
1892         block_order   = order;
1893         n_block_order = n_blocks;
1894 }
1895
1896 /**
1897  * Run the register allocator for the current register class.
1898  */
1899 static void be_pref_alloc_cls(void)
1900 {
1901         int i;
1902
1903         lv = be_assure_liveness(birg);
1904         be_liveness_assure_sets(lv);
1905
1906         ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
1907
1908         DB((dbg, LEVEL_2, "=== Allocating registers of %s ===\n", cls->name));
1909
1910         be_clear_links(irg);
1911
1912         irg_block_walk_graph(irg, NULL, analyze_block, NULL);
1913         if (create_congruence_classes)
1914                 combine_congruence_classes();
1915
1916         for (i = 0; i < n_block_order; ++i) {
1917                 ir_node *block = block_order[i];
1918                 allocate_coalesce_block(block, NULL);
1919         }
1920
1921         ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
1922 }
1923
1924 static void dump(int mask, ir_graph *irg, const char *suffix)
1925 {
1926         if (birg->main_env->options->dump_flags & mask)
1927                 dump_ir_graph(irg, suffix);
1928 }
1929
1930 /**
1931  * Run the spiller on the current graph.
1932  */
1933 static void spill(void)
1934 {
1935         /* make sure all nodes show their real register pressure */
1936         be_timer_push(T_RA_CONSTR);
1937         be_pre_spill_prepare_constr(birg, cls);
1938         be_timer_pop(T_RA_CONSTR);
1939
1940         dump(DUMP_RA, irg, "-spillprepare");
1941
1942         /* spill */
1943         be_timer_push(T_RA_SPILL);
1944         be_do_spill(birg, cls);
1945         be_timer_pop(T_RA_SPILL);
1946
1947         be_timer_push(T_RA_SPILL_APPLY);
1948         check_for_memory_operands(irg);
1949         be_timer_pop(T_RA_SPILL_APPLY);
1950
1951         dump(DUMP_RA, irg, "-spill");
1952 }
1953
1954 /**
1955  * The pref register allocator for a whole procedure.
1956  */
1957 static void be_pref_alloc(be_irg_t *new_birg)
1958 {
1959         const arch_env_t *arch_env = new_birg->main_env->arch_env;
1960         int   n_cls                = arch_env_get_n_reg_class(arch_env);
1961         int   c;
1962
1963         obstack_init(&obst);
1964
1965         birg      = new_birg;
1966         irg       = be_get_birg_irg(birg);
1967         execfreqs = birg->exec_freq;
1968
1969         /* determine a good coloring order */
1970         determine_block_order();
1971
1972         for (c = 0; c < n_cls; ++c) {
1973                 cls             = arch_env_get_reg_class(arch_env, c);
1974                 default_cls_req = NULL;
1975                 if (arch_register_class_flags(cls) & arch_register_class_flag_manual_ra)
1976                         continue;
1977
1978                 stat_ev_ctx_push_str("regcls", cls->name);
1979
1980                 n_regs      = arch_register_class_n_regs(cls);
1981                 normal_regs = rbitset_malloc(n_regs);
1982                 be_abi_set_non_ignore_regs(birg->abi, cls, normal_regs);
1983
1984                 spill();
1985
1986                 /* verify schedule and register pressure */
1987                 be_timer_push(T_VERIFY);
1988                 if (birg->main_env->options->vrfy_option == BE_VRFY_WARN) {
1989                         be_verify_schedule(birg);
1990                         be_verify_register_pressure(birg, cls, irg);
1991                 } else if (birg->main_env->options->vrfy_option == BE_VRFY_ASSERT) {
1992                         assert(be_verify_schedule(birg) && "Schedule verification failed");
1993                         assert(be_verify_register_pressure(birg, cls, irg)
1994                                 && "Register pressure verification failed");
1995                 }
1996                 be_timer_pop(T_VERIFY);
1997
1998                 be_timer_push(T_RA_COLOR);
1999                 be_pref_alloc_cls();
2000                 be_timer_pop(T_RA_COLOR);
2001
2002                 /* we most probably constructed new Phis so liveness info is invalid
2003                  * now */
2004                 /* TODO: test liveness_introduce */
2005                 be_liveness_invalidate(lv);
2006                 free(normal_regs);
2007
2008                 stat_ev_ctx_pop("regcls");
2009         }
2010
2011         be_timer_push(T_RA_SPILL_APPLY);
2012         be_abi_fix_stack_nodes(birg->abi);
2013         be_timer_pop(T_RA_SPILL_APPLY);
2014
2015         be_timer_push(T_VERIFY);
2016         if (birg->main_env->options->vrfy_option == BE_VRFY_WARN) {
2017                 be_verify_register_allocation(birg);
2018         } else if (birg->main_env->options->vrfy_option == BE_VRFY_ASSERT) {
2019                 assert(be_verify_register_allocation(birg)
2020                                 && "Register allocation invalid");
2021         }
2022         be_timer_pop(T_VERIFY);
2023
2024         obstack_free(&obst, NULL);
2025 }
2026
2027 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_pref_alloc);
2028 void be_init_pref_alloc(void)
2029 {
2030         static be_ra_t be_ra_pref = {
2031                 be_pref_alloc,
2032         };
2033         lc_opt_entry_t *be_grp              = lc_opt_get_grp(firm_opt_get_root(), "be");
2034         lc_opt_entry_t *prefalloc_group = lc_opt_get_grp(be_grp, "prefalloc");
2035         lc_opt_add_table(prefalloc_group, options);
2036
2037         be_register_allocator("pref", &be_ra_pref);
2038         FIRM_DBG_REGISTER(dbg, "firm.be.prefalloc");
2039 }