nsz Git - libfirm/blob - ir/be/benewalloc.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       New approach to allocation and copy coalescing
  23  * @author      Matthias Braun
  24  * @date        14.2.2009
  25  * @version     $Id$
  26  *
  27  * ... WE NEED A NAME FOR THIS ...
  28  *
  29  * Only a proof of concept at this moment...
  30  *
  31  * The idea is to allocate registers in 2 passes:
  32  * 1. A first pass to determine "preferred" registers for live-ranges. This
  33  *    calculates for each register and each live-range a value indicating
  34  *    the usefulness. (You can roughly think of the value as the negative
  35  *    costs needed for copies when the value is in the specific registers...)
  36  *
  37  * 2. Walk blocks and assigns registers in a greedy fashion. Preferring
  38  *    registers with high preferences. When register constraints are not met,
  39  *    add copies and split live-ranges.
  40  *
  41  * TODO:
  42  *  - make use of free registers in the permute_values code
  43  *  - think about a smarter sequence of visiting the blocks. Sorted by
  44  *    execfreq might be good, or looptree from inner to outermost loops going
  45  *    over blocks in a reverse postorder
  46  *  - propagate preferences through Phis
  47  */
  48 #include "config.h"
  49
  50 #include <float.h>
  51 #include <stdbool.h>
  52
  53 #include "error.h"
  54 #include "execfreq.h"
  55 #include "ircons.h"
  56 #include "irdom.h"
  57 #include "iredges_t.h"
  58 #include "irgraph_t.h"
  59 #include "irgwalk.h"
  60 #include "irnode_t.h"
  61 #include "obst.h"
  62 #include "raw_bitset.h"
  63 #include "unionfind.h"
  64
  65 #include "beabi.h"
  66 #include "bechordal_t.h"
  67 #include "be.h"
  68 #include "beirg.h"
  69 #include "belive_t.h"
  70 #include "bemodule.h"
  71 #include "benode_t.h"
  72 #include "bera.h"
  73 #include "besched.h"
  74 #include "bespill.h"
  75 #include "bespillutil.h"
  76 #include "beverify.h"
  77
  78 #include "hungarian.h"
  79
  80 #define USE_FACTOR         1.0f
  81 #define DEF_FACTOR         1.0f
  82 #define NEIGHBOR_FACTOR    0.2f
  83 #define AFF_SHOULD_BE_SAME 0.5f
  84 #define AFF_PHI            1.0f
  85 #define SPLIT_DELTA        1.0f
  86
  87 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  88
  89 static struct obstack               obst;
  90 static be_irg_t                    *birg;
  91 static ir_graph                    *irg;
  92 static const arch_register_class_t *cls;
  93 static const arch_register_req_t   *default_cls_req;
  94 static be_lv_t                     *lv;
  95 static const ir_exec_freq          *execfreqs;
  96 static unsigned                     n_regs;
  97 static unsigned                    *normal_regs;
  98 static int                         *congruence_classes;
  99
 100 /** currently active assignments (while processing a basic block)
 101  * maps registers to values(their current copies) */
 102 static ir_node **assignments;
 103
 104 /**
 105  * allocation information: last_uses, register preferences
 106  * the information is per firm-node.
 107  */
 108 struct allocation_info_t {
 109         unsigned  last_uses;      /**< bitset indicating last uses (input pos) */
 110         ir_node  *current_value;  /**< copy of the value that should be used */
 111         ir_node  *original_value; /**< for copies point to original value */
 112         unsigned char should_be_same[2];
 113         float     prefs[0];       /**< register preferences */
 114 };
 115 typedef struct allocation_info_t allocation_info_t;
 116
 117 /** helper datastructure used when sorting register preferences */
 118 struct reg_pref_t {
 119         unsigned num;
 120         float    pref;
 121 };
 122 typedef struct reg_pref_t reg_pref_t;
 123
 124 /** per basic-block information */
 125 struct block_info_t {
 126         bool     processed;       /**< indicate wether block is processed */
 127         ir_node *assignments[0];  /**< register assignments at end of block */
 128 };
 129 typedef struct block_info_t block_info_t;
 130
 131 /**
 132  * Get the allocation info for a node.
 133  * The info is allocated on the first visit of a node.
 134  */
 135 static allocation_info_t *get_allocation_info(ir_node *node)
 136 {
 137         allocation_info_t *info = get_irn_link(node);
 138         if (info == NULL) {
 139                 info = OALLOCFZ(&obst, allocation_info_t, prefs, n_regs);
 140                 info->current_value  = node;
 141                 info->original_value = node;
 142                 set_irn_link(node, info);
 143         }
 144
 145         return info;
 146 }
 147
 148 /**
 149  * Get allocation information for a basic block
 150  */
 151 static block_info_t *get_block_info(ir_node *block)
 152 {
 153         block_info_t *info = get_irn_link(block);
 154
 155         assert(is_Block(block));
 156         if (info == NULL) {
 157                 info = OALLOCFZ(&obst, block_info_t, assignments, n_regs);
 158                 set_irn_link(block, info);
 159         }
 160
 161         return info;
 162 }
 163
 164 /**
 165  * Get default register requirement for the current register class
 166  */
 167 static const arch_register_req_t *get_default_req_current_cls(void)
 168 {
 169         if (default_cls_req == NULL) {
 170                 struct obstack      *obst = get_irg_obstack(irg);
 171                 arch_register_req_t *req  = OALLOCZ(obst, arch_register_req_t);
 172
 173                 req->type = arch_register_req_type_normal;
 174                 req->cls  = cls;
 175
 176                 default_cls_req = req;
 177         }
 178         return default_cls_req;
 179 }
 180
 181 /**
 182  * Link the allocation info of a node to a copy.
 183  * Afterwards, both nodes uses the same allocation info.
 184  * Copy must not have an allocation info assigned yet.
 185  *
 186  * @param copy   the node that gets the allocation info assigned
 187  * @param value  the original node
 188  */
 189 static void mark_as_copy_of(ir_node *copy, ir_node *value)
 190 {
 191         ir_node           *original;
 192         allocation_info_t *info      = get_allocation_info(value);
 193         allocation_info_t *copy_info = get_allocation_info(copy);
 194
 195         /* find original value */
 196         original = info->original_value;
 197         if (original != value) {
 198                 info = get_allocation_info(original);
 199         }
 200
 201         assert(info->original_value == original);
 202         info->current_value = copy;
 203
 204         /* the copy should not be linked to something else yet */
 205         assert(copy_info->original_value == copy);
 206         copy_info->original_value = original;
 207
 208         /* copy over allocation preferences */
 209         memcpy(copy_info->prefs, info->prefs, n_regs * sizeof(copy_info->prefs[0]));
 210 }
 211
 212 /**
 213  * Calculate the penalties for every register on a node and its live neighbors.
 214  *
 215  * @param live_nodes  the set of live nodes at the current position, may be NULL
 216  * @param penalty     the penalty to subtract from
 217  * @param limited     a raw bitset containing the limited set for the node
 218  * @param node        the node
 219  */
 220 static void give_penalties_for_limits(const ir_nodeset_t *live_nodes,
 221                                       float penalty, const unsigned* limited,
 222                                       ir_node *node)
 223 {
 224         ir_nodeset_iterator_t iter;
 225         unsigned              r;
 226         allocation_info_t     *info = get_allocation_info(node);
 227         ir_node               *neighbor;
 228
 229         /* give penalty for all forbidden regs */
 230         for (r = 0; r < n_regs; ++r) {
 231                 if (rbitset_is_set(limited, r))
 232                         continue;
 233
 234                 info->prefs[r] -= penalty;
 235         }
 236
 237         /* all other live values should get a penalty for allowed regs */
 238         if (live_nodes == NULL)
 239                 return;
 240
 241         /* TODO: reduce penalty if there are multiple allowed registers... */
 242         penalty *= NEIGHBOR_FACTOR;
 243         foreach_ir_nodeset(live_nodes, neighbor, iter) {
 244                 allocation_info_t *neighbor_info;
 245
 246                 /* TODO: if op is used on multiple inputs we might not do a
 247                  * continue here */
 248                 if (neighbor == node)
 249                         continue;
 250
 251                 neighbor_info = get_allocation_info(neighbor);
 252                 for (r = 0; r < n_regs; ++r) {
 253                         if (!rbitset_is_set(limited, r))
 254                                 continue;
 255
 256                         neighbor_info->prefs[r] -= penalty;
 257                 }
 258         }
 259 }
 260
 261 /**
 262  * Calculate the preferences of a definition for the current register class.
 263  * If the definition uses a limited set of registers, reduce the preferences
 264  * for the limited register on the node and its neighbors.
 265  *
 266  * @param live_nodes  the set of live nodes at the current node
 267  * @param weight      the weight
 268  * @param node        the current node
 269  */
 270 static void check_defs(const ir_nodeset_t *live_nodes, float weight,
 271                        ir_node *node)
 272 {
 273         const arch_register_req_t *req;
 274
 275         if (get_irn_mode(node) == mode_T) {
 276                 const ir_edge_t *edge;
 277                 foreach_out_edge(node, edge) {
 278                         ir_node *proj = get_edge_src_irn(edge);
 279                         check_defs(live_nodes, weight, proj);
 280                 }
 281                 return;
 282         }
 283
 284         if (!arch_irn_consider_in_reg_alloc(cls, node))
 285                 return;
 286
 287         req = arch_get_register_req_out(node);
 288         if (req->type & arch_register_req_type_limited) {
 289                 const unsigned *limited = req->limited;
 290                 float           penalty = weight * DEF_FACTOR;
 291                 give_penalties_for_limits(live_nodes, penalty, limited, node);
 292         }
 293
 294         if (req->type & arch_register_req_type_should_be_same) {
 295                 ir_node           *insn  = skip_Proj(node);
 296                 allocation_info_t *info  = get_allocation_info(node);
 297                 int                arity = get_irn_arity(insn);
 298                 int                i;
 299
 300                 float factor = 1.0f / rbitset_popcnt(&req->other_same, arity);
 301                 for (i = 0; i < arity; ++i) {
 302                         ir_node           *op;
 303                         unsigned           r;
 304                         allocation_info_t *op_info;
 305
 306                         if (!rbitset_is_set(&req->other_same, i))
 307                                 continue;
 308
 309                         op = get_irn_n(insn, i);
 310
 311                         /* if we the value at the should_be_same input doesn't die at the
 312                          * node, then it is no use to propagate the constraints (since a
 313                          * copy will emerge anyway) */
 314                         if (ir_nodeset_contains(live_nodes, op))
 315                                 continue;
 316
 317                         op_info = get_allocation_info(op);
 318                         for (r = 0; r < n_regs; ++r) {
 319                                 op_info->prefs[r] += info->prefs[r] * factor;
 320                         }
 321                 }
 322         }
 323 }
 324
 325 /**
 326  * Walker: Runs an a block calculates the preferences for any
 327  * node and every register from the considered register class.
 328  */
 329 static void analyze_block(ir_node *block, void *data)
 330 {
 331         float         weight = get_block_execfreq(execfreqs, block);
 332         ir_nodeset_t  live_nodes;
 333         ir_node      *node;
 334         (void) data;
 335
 336         ir_nodeset_init(&live_nodes);
 337         be_liveness_end_of_block(lv, cls, block, &live_nodes);
 338
 339         sched_foreach_reverse(block, node) {
 340                 allocation_info_t *info;
 341                 int                i;
 342                 int                arity;
 343
 344                 if (is_Phi(node))
 345                         break;
 346
 347                 check_defs(&live_nodes, weight, node);
 348
 349                 /* mark last uses */
 350                 arity = get_irn_arity(node);
 351
 352                 /* the allocation info node currently only uses 1 unsigned value
 353                    to mark last used inputs. So we will fail for a node with more than
 354                    32 inputs. */
 355                 if (arity >= (int) sizeof(unsigned) * 8) {
 356                         panic("Node with more than %d inputs not supported yet",
 357                                         (int) sizeof(unsigned) * 8);
 358                 }
 359
 360                 info = get_allocation_info(node);
 361                 for (i = 0; i < arity; ++i) {
 362                         ir_node *op = get_irn_n(node, i);
 363                         if (!arch_irn_consider_in_reg_alloc(cls, op))
 364                                 continue;
 365
 366                         /* last usage of a value? */
 367                         if (!ir_nodeset_contains(&live_nodes, op)) {
 368                                 rbitset_set(&info->last_uses, i);
 369                         }
 370                 }
 371
 372                 be_liveness_transfer(cls, node, &live_nodes);
 373
 374                 /* update weights based on usage constraints */
 375                 for (i = 0; i < arity; ++i) {
 376                         const arch_register_req_t *req;
 377                         const unsigned            *limited;
 378                         ir_node                   *op = get_irn_n(node, i);
 379
 380                         if (!arch_irn_consider_in_reg_alloc(cls, op))
 381                                 continue;
 382
 383                         req = arch_get_register_req(node, i);
 384                         if (!(req->type & arch_register_req_type_limited))
 385                                 continue;
 386
 387                         limited = req->limited;
 388                         give_penalties_for_limits(&live_nodes, weight * USE_FACTOR, limited,
 389                                                   op);
 390                 }
 391         }
 392
 393         ir_nodeset_destroy(&live_nodes);
 394 }
 395
 396 static void create_congurence_class(ir_node *node, void *data)
 397 {
 398         (void) data;
 399         if (is_Phi(node)) {
 400                 int      i;
 401                 int      arity   = get_irn_arity(node);
 402                 unsigned phi_idx = get_irn_idx(node);
 403                 phi_idx     = uf_find(congruence_classes, phi_idx);
 404                 for (i = 0; i < arity; ++i) {
 405                         ir_node *op     = get_Phi_pred(node, i);
 406                         int      op_idx = get_irn_idx(op);
 407                         op_idx  = uf_find(congruence_classes, op_idx);
 408                         phi_idx = uf_union(congruence_classes, phi_idx, op_idx);
 409                 }
 410                 return;
 411         }
 412         /* should be same constraint? */
 413         if (is_Proj(node)) {
 414                 const arch_register_req_t *req = arch_get_register_req_out(node);
 415                 if (req->type & arch_register_req_type_should_be_same) {
 416                         ir_node *pred  = get_Proj_pred(node);
 417                         int      arity = get_irn_arity(pred);
 418                         int      i;
 419                         unsigned node_idx = get_irn_idx(node);
 420                         node_idx          = uf_find(congruence_classes, node_idx);
 421
 422                         for (i = 0; i < arity; ++i) {
 423                                 ir_node *op;
 424                                 unsigned op_idx;
 425
 426                                 if (!rbitset_is_set(&req->other_same, i))
 427                                         continue;
 428
 429                                 op     = get_irn_n(pred, i);
 430                                 op_idx = get_irn_idx(op);
 431                                 op_idx = uf_find(congruence_classes, op_idx);
 432                                 node_idx = uf_union(congruence_classes, node_idx, op_idx);
 433                         }
 434                 }
 435                 return;
 436         }
 437 }
 438
 439 static void merge_congruence_prefs(ir_node *node, void *data)
 440 {
 441         allocation_info_t *info;
 442         allocation_info_t *head_info;
 443         unsigned node_idx = get_irn_idx(node);
 444         unsigned node_set = uf_find(congruence_classes, node_idx);
 445         unsigned r;
 446
 447         (void) data;
 448
 449         /* head of congruence class or not in any class */
 450         if (node_set == node_idx)
 451                 return;
 452
 453         if (!arch_irn_consider_in_reg_alloc(cls, node))
 454                 return;
 455
 456         head_info = get_allocation_info(get_idx_irn(irg, node_set));
 457         info      = get_allocation_info(node);
 458
 459         for (r = 0; r < n_regs; ++r) {
 460                 head_info->prefs[r] += info->prefs[r];
 461         }
 462 }
 463
 464 static void set_congruence_prefs(ir_node *node, void *data)
 465 {
 466         allocation_info_t *info;
 467         allocation_info_t *head_info;
 468         unsigned node_idx = get_irn_idx(node);
 469         unsigned node_set = uf_find(congruence_classes, node_idx);
 470
 471         (void) data;
 472
 473         /* head of congruence class or not in any class */
 474         if (node_set == node_idx)
 475                 return;
 476
 477         if (!arch_irn_consider_in_reg_alloc(cls, node))
 478                 return;
 479
 480         head_info = get_allocation_info(get_idx_irn(irg, node_set));
 481         info      = get_allocation_info(node);
 482
 483         memcpy(info->prefs, head_info->prefs, n_regs * sizeof(info->prefs[0]));
 484 }
 485
 486 static void combine_congruence_classes(void)
 487 {
 488         size_t n = get_irg_last_idx(irg);
 489         congruence_classes = XMALLOCN(int, n);
 490         uf_init(congruence_classes, n);
 491
 492         /* create congruence classes */
 493         irg_walk_graph(irg, create_congurence_class, NULL, NULL);
 494         /* merge preferences */
 495         irg_walk_graph(irg, merge_congruence_prefs, NULL, NULL);
 496         irg_walk_graph(irg, set_congruence_prefs, NULL, NULL);
 497 }
 498
 499
 500
 501
 502
 503 /**
 504  * Assign register reg to the given node.
 505  *
 506  * @param node  the node
 507  * @param reg   the register
 508  */
 509 static void use_reg(ir_node *node, const arch_register_t *reg)
 510 {
 511         unsigned r = arch_register_get_index(reg);
 512         assignments[r] = node;
 513         arch_set_irn_register(node, reg);
 514 }
 515
 516 static void free_reg_of_value(ir_node *node)
 517 {
 518         const arch_register_t *reg;
 519         unsigned               r;
 520
 521         if (!arch_irn_consider_in_reg_alloc(cls, node))
 522                 return;
 523
 524         reg        = arch_get_irn_register(node);
 525         r          = arch_register_get_index(reg);
 526         /* assignment->value may be NULL if a value is used at 2 inputs
 527            so it gets freed twice. */
 528         assert(assignments[r] == node || assignments[r] == NULL);
 529         assignments[r] = NULL;
 530 }
 531
 532 /**
 533  * Compare two register preferences in decreasing order.
 534  */
 535 static int compare_reg_pref(const void *e1, const void *e2)
 536 {
 537         const reg_pref_t *rp1 = (const reg_pref_t*) e1;
 538         const reg_pref_t *rp2 = (const reg_pref_t*) e2;
 539         if (rp1->pref < rp2->pref)
 540                 return 1;
 541         if (rp1->pref > rp2->pref)
 542                 return -1;
 543         return 0;
 544 }
 545
 546 static void fill_sort_candidates(reg_pref_t *regprefs,
 547                                  const allocation_info_t *info)
 548 {
 549         unsigned r;
 550
 551         for (r = 0; r < n_regs; ++r) {
 552                 float pref = info->prefs[r];
 553                 regprefs[r].num  = r;
 554                 regprefs[r].pref = pref;
 555         }
 556         /* TODO: use a stable sort here to avoid unnecessary register jumping */
 557         qsort(regprefs, n_regs, sizeof(regprefs[0]), compare_reg_pref);
 558 }
 559
 560 static bool try_optimistic_split(ir_node *to_split, ir_node *before,
 561                                  float pref, float pref_delta,
 562                                  unsigned *output_regs)
 563 {
 564         const arch_register_t *reg;
 565         ir_node               *original_insn;
 566         ir_node               *block;
 567         ir_node               *copy;
 568         unsigned               r;
 569         unsigned               i;
 570         allocation_info_t     *info = get_allocation_info(to_split);
 571         reg_pref_t            *prefs;
 572         float                  delta;
 573
 574         (void) pref;
 575
 576         /* stupid hack: don't optimisticallt split don't spill nodes...
 577          * (so we don't split away the values produced because of
 578          *  must_be_different constraints) */
 579         original_insn = skip_Proj(info->original_value);
 580         if (arch_irn_get_flags(original_insn) & arch_irn_flags_dont_spill)
 581                 return false;
 582
 583         /* find the best free position where we could move to */
 584         prefs = ALLOCAN(reg_pref_t, n_regs);
 585         fill_sort_candidates(prefs, info);
 586         for (i = 0; i < n_regs; ++i) {
 587                 r = prefs[i].num;
 588                 if (!rbitset_is_set(normal_regs, r))
 589                         continue;
 590                 if (rbitset_is_set(output_regs, r))
 591                         continue;
 592                 if (assignments[r] == NULL)
 593                         break;
 594         }
 595         if (i >= n_regs) {
 596                 return false;
 597         }
 598         /* TODO: use execfreq somehow... */
 599         delta = pref_delta + prefs[i].pref;
 600         if (delta < SPLIT_DELTA) {
 601                 DB((dbg, LEVEL_3, "Not doing optimistical split, win %f too low\n",
 602                     delta));
 603                 return false;
 604         }
 605
 606         reg   = arch_register_for_index(cls, r);
 607         block = get_nodes_block(before);
 608         copy = be_new_Copy(cls, block, to_split);
 609         mark_as_copy_of(copy, to_split);
 610         free_reg_of_value(to_split);
 611         use_reg(copy, reg);
 612         sched_add_before(before, copy);
 613
 614         DB((dbg, LEVEL_3,
 615             "Optimistic live-range split %+F move %+F -> %s before %+F (win %f)\n",
 616             copy, to_split, reg->name, before, delta));
 617         return true;
 618 }
 619
 620 /**
 621  * Determine and assign a register for node @p node
 622  */
 623 static void assign_reg(const ir_node *block, ir_node *node,
 624                        unsigned *output_regs)
 625 {
 626         const arch_register_t     *reg;
 627         allocation_info_t         *info;
 628         const arch_register_req_t *req;
 629         reg_pref_t                *reg_prefs;
 630         ir_node                   *in_node;
 631         unsigned                   i;
 632         const unsigned            *allowed_regs;
 633         unsigned                   r;
 634
 635         assert(arch_irn_consider_in_reg_alloc(cls, node));
 636
 637         /* preassigned register? */
 638         reg = arch_get_irn_register(node);
 639         if (reg != NULL) {
 640                 DB((dbg, LEVEL_2, "Preassignment %+F -> %s\n", node, reg->name));
 641                 use_reg(node, reg);
 642                 return;
 643         }
 644
 645         /* give should_be_same boni */
 646         info = get_allocation_info(node);
 647         req  = arch_get_register_req_out(node);
 648
 649         in_node = skip_Proj(node);
 650         if (req->type & arch_register_req_type_should_be_same) {
 651                 float weight = get_block_execfreq(execfreqs, block);
 652                 int   arity  = get_irn_arity(in_node);
 653                 int   i;
 654
 655                 assert(arity <= (int) sizeof(req->other_same) * 8);
 656                 for (i = 0; i < arity; ++i) {
 657                         ir_node               *in;
 658                         const arch_register_t *reg;
 659                         unsigned               r;
 660                         if (!rbitset_is_set(&req->other_same, i))
 661                                 continue;
 662
 663                         in  = get_irn_n(in_node, i);
 664                         reg = arch_get_irn_register(in);
 665                         assert(reg != NULL);
 666                         r = arch_register_get_index(reg);
 667
 668                         /* if the value didn't die here then we should not propagate the
 669                          * should_be_same info */
 670                         if (assignments[r] == in)
 671                                 continue;
 672
 673                         info->prefs[r] += weight * AFF_SHOULD_BE_SAME;
 674                 }
 675         }
 676
 677         /* create list of register candidates and sort by their preference */
 678         DB((dbg, LEVEL_2, "Candidates for %+F:", node));
 679         reg_prefs = alloca(n_regs * sizeof(reg_prefs[0]));
 680         fill_sort_candidates(reg_prefs, info);
 681         for (i = 0; i < n_regs; ++i) {
 682                 unsigned num = reg_prefs[i].num;
 683                 const arch_register_t *reg;
 684
 685                 if (!rbitset_is_set(normal_regs, num))
 686                         continue;
 687
 688                 reg = arch_register_for_index(cls, num);
 689                 DB((dbg, LEVEL_2, " %s(%f)", reg->name, reg_prefs[i].pref));
 690         }
 691         DB((dbg, LEVEL_2, "\n"));
 692
 693         allowed_regs = normal_regs;
 694         if (req->type & arch_register_req_type_limited) {
 695                 allowed_regs = req->limited;
 696         }
 697
 698         for (i = 0; i < n_regs; ++i) {
 699                 r = reg_prefs[i].num;
 700                 if (!rbitset_is_set(allowed_regs, r))
 701                         continue;
 702                 if (assignments[r] == NULL)
 703                         break;
 704                 if (!is_Phi(node)) {
 705                         float    pref   = reg_prefs[i].pref;
 706                         float    delta  = i+1 < n_regs ? pref - reg_prefs[i+1].pref : 0;
 707                         ir_node *before = skip_Proj(node);
 708                         bool     res    = try_optimistic_split(assignments[r], before,
 709                                                                pref, delta,
 710                                                                output_regs);
 711                         if (res)
 712                                 break;
 713                 }
 714         }
 715         if (i >= n_regs) {
 716                 panic("No register left for %+F\n", node);
 717         }
 718
 719         reg = arch_register_for_index(cls, r);
 720         DB((dbg, LEVEL_2, "Assign %+F -> %s\n", node, reg->name));
 721         use_reg(node, reg);
 722 }
 723
 724 /**
 725  * Add an permutation in front of a node and change the assignments
 726  * due to this permutation.
 727  *
 728  * To understand this imagine a permutation like this:
 729  *
 730  * 1 -> 2
 731  * 2 -> 3
 732  * 3 -> 1, 5
 733  * 4 -> 6
 734  * 5
 735  * 6
 736  * 7 -> 7
 737  *
 738  * First we count how many destinations a single value has. At the same time
 739  * we can be sure that each destination register has at most 1 source register
 740  * (it can have 0 which means we don't care what value is in it).
 741  * We ignore all fullfilled permuations (like 7->7)
 742  * In a first pass we create as much copy instructions as possible as they
 743  * are generally cheaper than exchanges. We do this by counting into how many
 744  * destinations a register has to be copied (in the example it's 2 for register
 745  * 3, or 1 for the registers 1,2,4 and 7).
 746  * We can then create a copy into every destination register when the usecount
 747  * of that register is 0 (= noone else needs the value in the register).
 748  *
 749  * After this step we should have cycles left. We implement a cyclic permutation
 750  * of n registers with n-1 transpositions.
 751  *
 752  * @param live_nodes   the set of live nodes, updated due to live range split
 753  * @param before       the node before we add the permutation
 754  * @param permutation  the permutation array indices are the destination
 755  *                     registers, the values in the array are the source
 756  *                     registers.
 757  */
 758 static void permute_values(ir_nodeset_t *live_nodes, ir_node *before,
 759                              unsigned *permutation)
 760 {
 761         unsigned  *n_used = ALLOCANZ(unsigned, n_regs);
 762         ir_node   *block;
 763         unsigned   r;
 764
 765         /* determine how often each source register needs to be read */
 766         for (r = 0; r < n_regs; ++r) {
 767                 unsigned  old_reg = permutation[r];
 768                 ir_node  *value;
 769
 770                 value = assignments[old_reg];
 771                 if (value == NULL) {
 772                         /* nothing to do here, reg is not live. Mark it as fixpoint
 773                          * so we ignore it in the next steps */
 774                         permutation[r] = r;
 775                         continue;
 776                 }
 777
 778                 ++n_used[old_reg];
 779         }
 780
 781         block = get_nodes_block(before);
 782
 783         /* step1: create copies where immediately possible */
 784         for (r = 0; r < n_regs; /* empty */) {
 785                 ir_node *copy;
 786                 ir_node *src;
 787                 const arch_register_t *reg;
 788                 unsigned               old_r = permutation[r];
 789
 790                 /* - no need to do anything for fixed points.
 791                    - we can't copy if the value in the dest reg is still needed */
 792                 if (old_r == r || n_used[r] > 0) {
 793                         ++r;
 794                         continue;
 795                 }
 796
 797                 /* create a copy */
 798                 src  = assignments[old_r];
 799                 copy = be_new_Copy(cls, block, src);
 800                 sched_add_before(before, copy);
 801                 reg = arch_register_for_index(cls, r);
 802                 DB((dbg, LEVEL_2, "Copy %+F (from %+F, before %+F) -> %s\n",
 803                     copy, src, before, reg->name));
 804                 mark_as_copy_of(copy, src);
 805                 use_reg(copy, reg);
 806
 807                 if (live_nodes != NULL) {
 808                         ir_nodeset_insert(live_nodes, copy);
 809                 }
 810
 811                 /* old register has 1 user less, permutation is resolved */
 812                 assert(arch_register_get_index(arch_get_irn_register(src)) == old_r);
 813                 permutation[r] = r;
 814
 815                 assert(n_used[old_r] > 0);
 816                 --n_used[old_r];
 817                 if (n_used[old_r] == 0) {
 818                         if (live_nodes != NULL) {
 819                                 ir_nodeset_remove(live_nodes, src);
 820                         }
 821                         free_reg_of_value(src);
 822                 }
 823
 824                 /* advance or jump back (if this copy enabled another copy) */
 825                 if (old_r < r && n_used[old_r] == 0) {
 826                         r = old_r;
 827                 } else {
 828                         ++r;
 829                 }
 830         }
 831
 832         /* at this point we only have "cycles" left which we have to resolve with
 833          * perm instructions
 834          * TODO: if we have free registers left, then we should really use copy
 835          * instructions for any cycle longer than 2 registers...
 836          * (this is probably architecture dependent, there might be archs where
 837          *  copies are preferable even for 2-cycles) */
 838
 839         /* create perms with the rest */
 840         for (r = 0; r < n_regs; /* empty */) {
 841                 const arch_register_t *reg;
 842                 unsigned  old_r = permutation[r];
 843                 unsigned  r2;
 844                 ir_node  *in[2];
 845                 ir_node  *perm;
 846                 ir_node  *proj0;
 847                 ir_node  *proj1;
 848
 849                 if (old_r == r) {
 850                         ++r;
 851                         continue;
 852                 }
 853
 854                 /* we shouldn't have copies from 1 value to multiple destinations left*/
 855                 assert(n_used[old_r] == 1);
 856
 857                 /* exchange old_r and r2; after that old_r is a fixed point */
 858                 r2 = permutation[old_r];
 859
 860                 in[0] = assignments[r2];
 861                 in[1] = assignments[old_r];
 862                 perm = be_new_Perm(cls, block, 2, in);
 863                 sched_add_before(before, perm);
 864                 DB((dbg, LEVEL_2, "Perm %+F (perm %+F,%+F, before %+F)\n",
 865                     perm, in[0], in[1], before));
 866
 867                 proj0 = new_r_Proj(block, perm, get_irn_mode(in[0]), 0);
 868                 mark_as_copy_of(proj0, in[0]);
 869                 reg = arch_register_for_index(cls, old_r);
 870                 use_reg(proj0, reg);
 871
 872                 proj1 = new_r_Proj(block, perm, get_irn_mode(in[1]), 1);
 873                 mark_as_copy_of(proj1, in[1]);
 874                 reg = arch_register_for_index(cls, r2);
 875                 use_reg(proj1, reg);
 876
 877                 /* 1 value is now in the correct register */
 878                 permutation[old_r] = old_r;
 879                 /* the source of r changed to r2 */
 880                 permutation[r] = r2;
 881
 882                 /* if we have reached a fixpoint update data structures */
 883                 if (live_nodes != NULL) {
 884                         ir_nodeset_remove(live_nodes, in[0]);
 885                         ir_nodeset_remove(live_nodes, in[1]);
 886                         ir_nodeset_remove(live_nodes, proj0);
 887                         ir_nodeset_insert(live_nodes, proj1);
 888                 }
 889         }
 890
 891 #ifdef DEBUG_libfirm
 892         /* now we should only have fixpoints left */
 893         for (r = 0; r < n_regs; ++r) {
 894                 assert(permutation[r] == r);
 895         }
 896 #endif
 897 }
 898
 899 /**
 900  * Free regs for values last used.
 901  *
 902  * @param live_nodes   set of live nodes, will be updated
 903  * @param node         the node to consider
 904  */
 905 static void free_last_uses(ir_nodeset_t *live_nodes, ir_node *node)
 906 {
 907         allocation_info_t     *info      = get_allocation_info(node);
 908         const unsigned        *last_uses = &info->last_uses;
 909         int                    arity     = get_irn_arity(node);
 910         int                    i;
 911
 912         for (i = 0; i < arity; ++i) {
 913                 ir_node *op;
 914
 915                 /* check if one operand is the last use */
 916                 if (!rbitset_is_set(last_uses, i))
 917                         continue;
 918
 919                 op = get_irn_n(node, i);
 920                 free_reg_of_value(op);
 921                 ir_nodeset_remove(live_nodes, op);
 922         }
 923 }
 924
 925 /**
 926  * change inputs of a node to the current value (copies/perms)
 927  */
 928 static void rewire_inputs(ir_node *node)
 929 {
 930         int i;
 931         int arity = get_irn_arity(node);
 932
 933         for (i = 0; i < arity; ++i) {
 934                 ir_node           *op = get_irn_n(node, i);
 935                 allocation_info_t *info;
 936
 937                 if (!arch_irn_consider_in_reg_alloc(cls, op))
 938                         continue;
 939
 940                 info = get_allocation_info(op);
 941                 info = get_allocation_info(info->original_value);
 942                 if (info->current_value != op) {
 943                         set_irn_n(node, i, info->current_value);
 944                 }
 945         }
 946 }
 947
 948 /**
 949  * Create a bitset of registers occupied with value living through an
 950  * instruction
 951  */
 952 static void determine_live_through_regs(unsigned *bitset, ir_node *node)
 953 {
 954         const allocation_info_t *info = get_allocation_info(node);
 955         unsigned r;
 956         int i;
 957         int arity;
 958
 959         /* mark all used registers as potentially live-through */
 960         for (r = 0; r < n_regs; ++r) {
 961                 if (assignments[r] == NULL)
 962                         continue;
 963                 if (!rbitset_is_set(normal_regs, r))
 964                         continue;
 965
 966                 rbitset_set(bitset, r);
 967         }
 968
 969         /* remove registers of value dying at the instruction */
 970         arity = get_irn_arity(node);
 971         for (i = 0; i < arity; ++i) {
 972                 ir_node               *op;
 973                 const arch_register_t *reg;
 974
 975                 if (!rbitset_is_set(&info->last_uses, i))
 976                         continue;
 977
 978                 op  = get_irn_n(node, i);
 979                 reg = arch_get_irn_register(op);
 980                 rbitset_clear(bitset, arch_register_get_index(reg));
 981         }
 982 }
 983
 984 /**
 985  * Enforce constraints at a node by live range splits.
 986  *
 987  * @param  live_nodes  the set of live nodes, might be changed
 988  * @param  node        the current node
 989  */
 990 static void enforce_constraints(ir_nodeset_t *live_nodes, ir_node *node,
 991                                 unsigned *output_regs)
 992 {
 993         int arity = get_irn_arity(node);
 994         int i, dummy, res;
 995         hungarian_problem_t *bp;
 996         unsigned l, r;
 997         unsigned *assignment;
 998
 999         /* construct a list of register occupied by live-through values */
1000         unsigned *live_through_regs = NULL;
1001
1002         /* see if any use constraints are not met */
1003         bool good = true;
1004         for (i = 0; i < arity; ++i) {
1005                 ir_node                   *op = get_irn_n(node, i);
1006                 const arch_register_t     *reg;
1007                 const arch_register_req_t *req;
1008                 const unsigned            *limited;
1009                 unsigned                  r;
1010
1011                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1012                         continue;
1013
1014                 /* are there any limitations for the i'th operand? */
1015                 req = arch_get_register_req(node, i);
1016                 if (!(req->type & arch_register_req_type_limited))
1017                         continue;
1018
1019                 limited = req->limited;
1020                 reg     = arch_get_irn_register(op);
1021                 r       = arch_register_get_index(reg);
1022                 if (!rbitset_is_set(limited, r)) {
1023                         /* found an assignment outside the limited set */
1024                         good = false;
1025                         break;
1026                 }
1027         }
1028
1029         /* is any of the live-throughs using a constrained output register? */
1030         if (get_irn_mode(node) == mode_T) {
1031                 const ir_edge_t *edge;
1032
1033                 foreach_out_edge(node, edge) {
1034                         ir_node *proj = get_edge_src_irn(edge);
1035                         const arch_register_req_t *req;
1036
1037                         if (!arch_irn_consider_in_reg_alloc(cls, proj))
1038                                 continue;
1039
1040                         req = arch_get_register_req_out(proj);
1041                         if (!(req->type & arch_register_req_type_limited))
1042                                 continue;
1043
1044                         if (live_through_regs == NULL) {
1045                                 rbitset_alloca(live_through_regs, n_regs);
1046                                 determine_live_through_regs(live_through_regs, node);
1047                         }
1048
1049                         rbitset_or(output_regs, req->limited, n_regs);
1050                         if (rbitsets_have_common(req->limited, live_through_regs, n_regs)) {
1051                                 good = false;
1052                         }
1053                 }
1054         } else {
1055                 if (arch_irn_consider_in_reg_alloc(cls, node)) {
1056                         const arch_register_req_t *req = arch_get_register_req_out(node);
1057                         if (req->type & arch_register_req_type_limited) {
1058                                 rbitset_alloca(live_through_regs, n_regs);
1059                                 determine_live_through_regs(live_through_regs, node);
1060                                 if (rbitsets_have_common(req->limited, live_through_regs, n_regs)) {
1061                                         good = false;
1062                                         rbitset_or(output_regs, req->limited, n_regs);
1063                                 }
1064                         }
1065                 }
1066         }
1067
1068         if (good)
1069                 return;
1070
1071         /* create these arrays if we haven't yet */
1072         if (live_through_regs == NULL) {
1073                 rbitset_alloca(live_through_regs, n_regs);
1074         }
1075
1076         /* at this point we have to construct a bipartite matching problem to see
1077          * which values should go to which registers
1078          * Note: We're building the matrix in "reverse" - source registers are
1079          *       right, destinations left because this will produce the solution
1080          *       in the format required for permute_values.
1081          */
1082         bp = hungarian_new(n_regs, n_regs, HUNGARIAN_MATCH_PERFECT);
1083
1084         /* add all combinations, then remove not allowed ones */
1085         for (l = 0; l < n_regs; ++l) {
1086                 if (!rbitset_is_set(normal_regs, l)) {
1087                         hungarian_add(bp, l, l, 1);
1088                         continue;
1089                 }
1090
1091                 for (r = 0; r < n_regs; ++r) {
1092                         if (!rbitset_is_set(normal_regs, r))
1093                                 continue;
1094                         /* livethrough values may not use constrainted output registers */
1095                         if (rbitset_is_set(live_through_regs, l)
1096                                         && rbitset_is_set(output_regs, r))
1097                                 continue;
1098
1099                         hungarian_add(bp, r, l, l == r ? 9 : 8);
1100                 }
1101         }
1102
1103         for (i = 0; i < arity; ++i) {
1104                 ir_node                   *op = get_irn_n(node, i);
1105                 const arch_register_t     *reg;
1106                 const arch_register_req_t *req;
1107                 const unsigned            *limited;
1108                 unsigned                   current_reg;
1109
1110                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1111                         continue;
1112
1113                 req = arch_get_register_req(node, i);
1114                 if (!(req->type & arch_register_req_type_limited))
1115                         continue;
1116
1117                 limited     = req->limited;
1118                 reg         = arch_get_irn_register(op);
1119                 current_reg = arch_register_get_index(reg);
1120                 for (r = 0; r < n_regs; ++r) {
1121                         if (rbitset_is_set(limited, r))
1122                                 continue;
1123                         hungarian_remv(bp, r, current_reg);
1124                 }
1125         }
1126
1127         //hungarian_print_costmatrix(bp, 1);
1128         hungarian_prepare_cost_matrix(bp, HUNGARIAN_MODE_MAXIMIZE_UTIL);
1129
1130         assignment = ALLOCAN(unsigned, n_regs);
1131         res = hungarian_solve(bp, (int*) assignment, &dummy, 0);
1132         assert(res == 0);
1133
1134 #if 0
1135         fprintf(stderr, "Swap result:");
1136         for (i = 0; i < (int) n_regs; ++i) {
1137                 fprintf(stderr, " %d", assignment[i]);
1138         }
1139         fprintf(stderr, "\n");
1140 #endif
1141
1142         hungarian_free(bp);
1143
1144         permute_values(live_nodes, node, assignment);
1145 }
1146
1147 /** test wether a node @p n is a copy of the value of node @p of */
1148 static bool is_copy_of(ir_node *value, ir_node *test_value)
1149 {
1150         allocation_info_t *test_info;
1151         allocation_info_t *info;
1152
1153         if (value == test_value)
1154                 return true;
1155
1156         info      = get_allocation_info(value);
1157         test_info = get_allocation_info(test_value);
1158         return test_info->original_value == info->original_value;
1159 }
1160
1161 /**
1162  * find a value in the end-assignment of a basic block
1163  * @returns the index into the assignment array if found
1164  *          -1 if not found
1165  */
1166 static int find_value_in_block_info(block_info_t *info, ir_node *value)
1167 {
1168         unsigned   r;
1169         ir_node  **assignments = info->assignments;
1170         for (r = 0; r < n_regs; ++r) {
1171                 ir_node *a_value = assignments[r];
1172
1173                 if (a_value == NULL)
1174                         continue;
1175                 if (is_copy_of(a_value, value))
1176                         return (int) r;
1177         }
1178
1179         return -1;
1180 }
1181
1182 /**
1183  * Create the necessary permutations at the end of a basic block to fullfill
1184  * the register assignment for phi-nodes in the next block
1185  */
1186 static void add_phi_permutations(ir_node *block, int p)
1187 {
1188         unsigned   r;
1189         unsigned  *permutation;
1190         ir_node  **old_assignments;
1191         bool       need_permutation;
1192         ir_node   *node;
1193         ir_node   *pred = get_Block_cfgpred_block(block, p);
1194
1195         block_info_t *pred_info = get_block_info(pred);
1196
1197         /* predecessor not processed yet? nothing to do */
1198         if (!pred_info->processed)
1199                 return;
1200
1201         permutation = ALLOCAN(unsigned, n_regs);
1202         for (r = 0; r < n_regs; ++r) {
1203                 permutation[r] = r;
1204         }
1205
1206         /* check phi nodes */
1207         need_permutation = false;
1208         node = sched_first(block);
1209         for ( ; is_Phi(node); node = sched_next(node)) {
1210                 const arch_register_t *reg;
1211                 int                    regn;
1212                 int                    a;
1213                 ir_node               *op;
1214
1215                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1216                         continue;
1217
1218                 op = get_Phi_pred(node, p);
1219                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1220                         continue;
1221
1222                 a  = find_value_in_block_info(pred_info, op);
1223                 assert(a >= 0);
1224
1225                 reg  = arch_get_irn_register(node);
1226                 regn = arch_register_get_index(reg);
1227                 if (regn != a) {
1228                         permutation[regn] = a;
1229                         need_permutation  = true;
1230                 }
1231         }
1232
1233         if (need_permutation) {
1234                 /* permute values at end of predecessor */
1235                 old_assignments = assignments;
1236                 assignments     = pred_info->assignments;
1237                 permute_values(NULL, be_get_end_of_block_insertion_point(pred),
1238                                                  permutation);
1239                 assignments = old_assignments;
1240         }
1241
1242         /* change phi nodes to use the copied values */
1243         node = sched_first(block);
1244         for ( ; is_Phi(node); node = sched_next(node)) {
1245                 int      a;
1246                 ir_node *op;
1247
1248                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1249                         continue;
1250
1251                 op = get_Phi_pred(node, p);
1252                 /* no need to do anything for Unknown inputs */
1253                 if (!arch_irn_consider_in_reg_alloc(cls, op))
1254                         continue;
1255
1256                 /* we have permuted all values into the correct registers so we can
1257                    simply query which value occupies the phis register in the
1258                    predecessor */
1259                 a  = arch_register_get_index(arch_get_irn_register(node));
1260                 op = pred_info->assignments[a];
1261                 set_Phi_pred(node, p, op);
1262         }
1263 }
1264
1265 /**
1266  * Set preferences for a phis register based on the registers used on the
1267  * phi inputs.
1268  */
1269 static void adapt_phi_prefs(ir_node *phi)
1270 {
1271         int i;
1272         int arity = get_irn_arity(phi);
1273         ir_node           *block = get_nodes_block(phi);
1274         allocation_info_t *info  = get_allocation_info(phi);
1275
1276         for (i = 0; i < arity; ++i) {
1277                 ir_node               *op  = get_irn_n(phi, i);
1278                 const arch_register_t *reg = arch_get_irn_register(op);
1279                 ir_node               *pred_block;
1280                 block_info_t          *pred_block_info;
1281                 float                  weight;
1282                 unsigned               r;
1283
1284                 if (reg == NULL)
1285                         continue;
1286                 /* we only give the bonus if the predecessor already has registers
1287                  * assigned, otherwise we only see a dummy value
1288                  * and any conclusions about its register are useless */
1289                 pred_block = get_Block_cfgpred_block(block, i);
1290                 pred_block_info = get_block_info(pred_block);
1291                 if (!pred_block_info->processed)
1292                         continue;
1293
1294                 /* give bonus for already assigned register */
1295                 weight = get_block_execfreq(execfreqs, pred_block);
1296                 r      = arch_register_get_index(reg);
1297                 info->prefs[r] += weight * AFF_PHI;
1298         }
1299 }
1300
1301 /**
1302  * After a phi has been assigned a register propagate preference inputs
1303  * to the phi inputs.
1304  */
1305 static void propagate_phi_register(ir_node *phi, unsigned r)
1306 {
1307         int                    i;
1308         ir_node               *block = get_nodes_block(phi);
1309         int                    arity = get_irn_arity(phi);
1310
1311         for (i = 0; i < arity; ++i) {
1312                 ir_node           *op         = get_Phi_pred(phi, i);
1313                 allocation_info_t *info       = get_allocation_info(op);
1314                 ir_node           *pred_block = get_Block_cfgpred_block(block, i);
1315                 float              weight
1316                         = get_block_execfreq(execfreqs, pred_block) * AFF_PHI;
1317
1318                 if (info->prefs[r] >= weight)
1319                         continue;
1320
1321                 /* promote the prefered register */
1322                 info->prefs[r] = AFF_PHI * weight;
1323                 if (is_Phi(op))
1324                         propagate_phi_register(op, r);
1325         }
1326 }
1327
1328 /**
1329  * Walker: assign registers to all nodes of a block that
1330  * need registers from the currently considered register class.
1331  */
1332 static void allocate_coalesce_block(ir_node *block, void *data)
1333 {
1334         int                    i;
1335         ir_nodeset_t           live_nodes;
1336         ir_nodeset_iterator_t  iter;
1337         ir_node               *node, *start;
1338         int                    n_preds;
1339         block_info_t          *block_info;
1340         block_info_t         **pred_block_infos;
1341         ir_node              **phi_ins;
1342         unsigned              *output_regs; /**< collects registers which must not
1343                                                                                      be used for optimistic splits */
1344
1345         (void) data;
1346         DB((dbg, LEVEL_2, "* Block %+F\n", block));
1347
1348         /* clear assignments */
1349         block_info  = get_block_info(block);
1350         assignments = block_info->assignments;
1351
1352         ir_nodeset_init(&live_nodes);
1353
1354         /* gather regalloc infos of predecessor blocks */
1355         n_preds             = get_Block_n_cfgpreds(block);
1356         pred_block_infos    = ALLOCAN(block_info_t*, n_preds);
1357         for (i = 0; i < n_preds; ++i) {
1358                 ir_node      *pred      = get_Block_cfgpred_block(block, i);
1359                 block_info_t *pred_info = get_block_info(pred);
1360                 pred_block_infos[i]     = pred_info;
1361         }
1362
1363         phi_ins = ALLOCAN(ir_node*, n_preds);
1364
1365         /* collect live-in nodes and preassigned values */
1366         be_lv_foreach(lv, block, be_lv_state_in, i) {
1367                 const arch_register_t *reg;
1368                 int                    p;
1369                 bool                   need_phi = false;
1370
1371                 node = be_lv_get_irn(lv, block, i);
1372                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1373                         continue;
1374
1375                 /* check all predecessors for this value, if it is not everywhere the
1376                    same or unknown then we have to construct a phi
1377                    (we collect the potential phi inputs here) */
1378                 for (p = 0; p < n_preds; ++p) {
1379                         block_info_t *pred_info = pred_block_infos[p];
1380
1381                         if (!pred_info->processed) {
1382                                 /* use node for now, it will get fixed later */
1383                                 phi_ins[p] = node;
1384                                 need_phi   = true;
1385                         } else {
1386                                 int a = find_value_in_block_info(pred_info, node);
1387
1388                                 /* must live out of predecessor */
1389                                 assert(a >= 0);
1390                                 phi_ins[p] = pred_info->assignments[a];
1391                                 /* different value from last time? then we need a phi */
1392                                 if (p > 0 && phi_ins[p-1] != phi_ins[p]) {
1393                                         need_phi = true;
1394                                 }
1395                         }
1396                 }
1397
1398                 if (need_phi) {
1399                         ir_mode                   *mode = get_irn_mode(node);
1400                         const arch_register_req_t *req  = get_default_req_current_cls();
1401                         ir_node                   *phi;
1402                         int                        i;
1403
1404                         phi = new_r_Phi(block, n_preds, phi_ins, mode);
1405                         be_set_phi_reg_req(phi, req);
1406
1407                         DB((dbg, LEVEL_3, "Create Phi %+F (for %+F) -", phi, node));
1408 #ifdef DEBUG_libfirm
1409                         for (i = 0; i < n_preds; ++i) {
1410                                 DB((dbg, LEVEL_3, " %+F", phi_ins[i]));
1411                         }
1412                         DB((dbg, LEVEL_3, "\n"));
1413 #endif
1414                         mark_as_copy_of(phi, node);
1415                         sched_add_after(block, phi);
1416
1417                         node = phi;
1418                 } else {
1419                         allocation_info_t *info = get_allocation_info(node);
1420                         info->current_value = phi_ins[0];
1421
1422                         /* Grab 1 of the inputs we constructed (might not be the same as
1423                          * "node" as we could see the same copy of the value in all
1424                          * predecessors */
1425                         node = phi_ins[0];
1426                 }
1427
1428                 /* if the node already has a register assigned use it */
1429                 reg = arch_get_irn_register(node);
1430                 if (reg != NULL) {
1431                         /* TODO: consult pred-block infos here. The value could be copied
1432                            away in some/all predecessor blocks. We need to construct
1433                            phi-nodes in this case.
1434                            We even need to construct some Phi_0 like constructs in cases
1435                            where the predecessor allocation is not determined yet. */
1436                         use_reg(node, reg);
1437                 }
1438
1439                 /* remember that this node is live at the beginning of the block */
1440                 ir_nodeset_insert(&live_nodes, node);
1441         }
1442
1443         rbitset_alloca(output_regs, n_regs);
1444
1445         /* handle phis... */
1446         node = sched_first(block);
1447         for ( ; is_Phi(node); node = sched_next(node)) {
1448                 const arch_register_t *reg;
1449
1450                 if (!arch_irn_consider_in_reg_alloc(cls, node))
1451                         continue;
1452
1453                 /* fill in regs already assigned */
1454                 reg = arch_get_irn_register(node);
1455                 if (reg != NULL) {
1456                         use_reg(node, reg);
1457                 } else {
1458                         adapt_phi_prefs(node);
1459                         assign_reg(block, node, output_regs);
1460
1461                         reg = arch_get_irn_register(node);
1462                         propagate_phi_register(node, arch_register_get_index(reg));
1463                 }
1464         }
1465         start = node;
1466
1467         /* assign regs for live-in values */
1468         foreach_ir_nodeset(&live_nodes, node, iter) {
1469                 const arch_register_t *reg = arch_get_irn_register(node);
1470                 if (reg != NULL)
1471                         continue;
1472
1473                 assign_reg(block, node, output_regs);
1474                 /* shouldn't happen if we color in dominance order */
1475                 assert (!is_Phi(node));
1476         }
1477
1478         /* assign instructions in the block */
1479         for (node = start; !sched_is_end(node); node = sched_next(node)) {
1480                 unsigned r;
1481
1482                 rewire_inputs(node);
1483
1484                 /* enforce use constraints */
1485                 rbitset_clear_all(output_regs, n_regs);
1486                 enforce_constraints(&live_nodes, node, output_regs);
1487                 /* we may not use registers occupied here for optimistic splits */
1488                 for (r = 0; r < n_regs; ++r) {
1489                         if (assignments[r] != NULL)
1490                                 rbitset_set(output_regs, r);
1491                 }
1492
1493                 rewire_inputs(node);
1494
1495                 /* free registers of values last used at this instruction */
1496                 free_last_uses(&live_nodes, node);
1497
1498                 /* assign output registers */
1499                 /* TODO: 2 phases: first: pre-assigned ones, 2nd real regs */
1500                 if (get_irn_mode(node) == mode_T) {
1501                         const ir_edge_t *edge;
1502                         foreach_out_edge(node, edge) {
1503                                 ir_node *proj = get_edge_src_irn(edge);
1504                                 if (!arch_irn_consider_in_reg_alloc(cls, proj))
1505                                         continue;
1506                                 assign_reg(block, proj, output_regs);
1507                         }
1508                 } else if (arch_irn_consider_in_reg_alloc(cls, node)) {
1509                         assign_reg(block, node, output_regs);
1510                 }
1511         }
1512
1513         ir_nodeset_destroy(&live_nodes);
1514         assignments = NULL;
1515
1516         block_info->processed = true;
1517
1518         /* permute values at end of predecessor blocks in case of phi-nodes */
1519         if (n_preds > 1) {
1520                 int p;
1521                 for (p = 0; p < n_preds; ++p) {
1522                         add_phi_permutations(block, p);
1523                 }
1524         }
1525
1526         /* if we have exactly 1 successor then we might be able to produce phi
1527            copies now */
1528         if (get_irn_n_edges_kind(block, EDGE_KIND_BLOCK) == 1) {
1529                 const ir_edge_t *edge
1530                         = get_irn_out_edge_first_kind(block, EDGE_KIND_BLOCK);
1531                 ir_node      *succ      = get_edge_src_irn(edge);
1532                 int           p         = get_edge_src_pos(edge);
1533                 block_info_t *succ_info = get_block_info(succ);
1534
1535                 if (succ_info->processed) {
1536                         add_phi_permutations(succ, p);
1537                 }
1538         }
1539 }
1540
1541 /**
1542  * Run the register allocator for the current register class.
1543  */
1544 static void be_straight_alloc_cls(void)
1545 {
1546         lv = be_assure_liveness(birg);
1547         be_liveness_assure_sets(lv);
1548         be_liveness_assure_chk(lv);
1549
1550         ir_reserve_resources(irg, IR_RESOURCE_IRN_LINK);
1551
1552         DB((dbg, LEVEL_2, "=== Allocating registers of %s ===\n", cls->name));
1553
1554         be_clear_links(irg);
1555         irg_block_walk_graph(irg, NULL, analyze_block, NULL);
1556         combine_congruence_classes();
1557         /* we need some dominance pre-order walk to ensure we see all
1558          *  definitions/create copies before we encounter their users */
1559         dom_tree_walk_irg(irg, allocate_coalesce_block, NULL, NULL);
1560
1561         ir_free_resources(irg, IR_RESOURCE_IRN_LINK);
1562 }
1563
1564 static void dump(int mask, ir_graph *irg, const char *suffix,
1565                  void (*dumper)(ir_graph *, const char *))
1566 {
1567         if(birg->main_env->options->dump_flags & mask)
1568                 be_dump(irg, suffix, dumper);
1569 }
1570
1571 /**
1572  * Run the spiller on the current graph.
1573  */
1574 static void spill(void)
1575 {
1576         /* make sure all nodes show their real register pressure */
1577         BE_TIMER_PUSH(t_ra_constr);
1578         be_pre_spill_prepare_constr(birg, cls);
1579         BE_TIMER_POP(t_ra_constr);
1580
1581         dump(DUMP_RA, irg, "-spillprepare", dump_ir_block_graph_sched);
1582
1583         /* spill */
1584         BE_TIMER_PUSH(t_ra_spill);
1585         be_do_spill(birg, cls);
1586         BE_TIMER_POP(t_ra_spill);
1587
1588         BE_TIMER_PUSH(t_ra_spill_apply);
1589         check_for_memory_operands(irg);
1590         BE_TIMER_POP(t_ra_spill_apply);
1591
1592         dump(DUMP_RA, irg, "-spill", dump_ir_block_graph_sched);
1593 }
1594
1595 /**
1596  * The straight register allocator for a whole procedure.
1597  */
1598 static void be_straight_alloc(be_irg_t *new_birg)
1599 {
1600         const arch_env_t *arch_env = new_birg->main_env->arch_env;
1601         int   n_cls                = arch_env_get_n_reg_class(arch_env);
1602         int   c;
1603
1604         obstack_init(&obst);
1605
1606         birg      = new_birg;
1607         irg       = be_get_birg_irg(birg);
1608         execfreqs = birg->exec_freq;
1609
1610         /* TODO: extract some of the stuff from bechordal allocator, like
1611          * statistics, time measurements, etc. and use them here too */
1612
1613         for (c = 0; c < n_cls; ++c) {
1614                 cls             = arch_env_get_reg_class(arch_env, c);
1615                 default_cls_req = NULL;
1616                 if (arch_register_class_flags(cls) & arch_register_class_flag_manual_ra)
1617                         continue;
1618
1619                 stat_ev_ctx_push_str("regcls", cls->name);
1620
1621                 n_regs      = arch_register_class_n_regs(cls);
1622                 normal_regs = rbitset_malloc(n_regs);
1623                 be_abi_set_non_ignore_regs(birg->abi, cls, normal_regs);
1624
1625                 spill();
1626
1627                 /* verify schedule and register pressure */
1628                 BE_TIMER_PUSH(t_verify);
1629                 if (birg->main_env->options->vrfy_option == BE_VRFY_WARN) {
1630                         be_verify_schedule(birg);
1631                         be_verify_register_pressure(birg, cls, irg);
1632                 } else if (birg->main_env->options->vrfy_option == BE_VRFY_ASSERT) {
1633                         assert(be_verify_schedule(birg) && "Schedule verification failed");
1634                         assert(be_verify_register_pressure(birg, cls, irg)
1635                                 && "Register pressure verification failed");
1636                 }
1637                 BE_TIMER_POP(t_verify);
1638
1639                 BE_TIMER_PUSH(t_ra_color);
1640                 be_straight_alloc_cls();
1641                 BE_TIMER_POP(t_ra_color);
1642
1643                 /* we most probably constructed new Phis so liveness info is invalid
1644                  * now */
1645                 /* TODO: test liveness_introduce */
1646                 be_liveness_invalidate(lv);
1647                 free(normal_regs);
1648
1649                 stat_ev_ctx_pop("regcls");
1650         }
1651
1652         BE_TIMER_PUSH(t_ra_spill_apply);
1653         be_abi_fix_stack_nodes(birg->abi);
1654         BE_TIMER_POP(t_ra_spill_apply);
1655
1656         BE_TIMER_PUSH(t_verify);
1657         if (birg->main_env->options->vrfy_option == BE_VRFY_WARN) {
1658                 be_verify_register_allocation(birg);
1659         } else if (birg->main_env->options->vrfy_option == BE_VRFY_ASSERT) {
1660                 assert(be_verify_register_allocation(birg)
1661                                 && "Register allocation invalid");
1662         }
1663         BE_TIMER_POP(t_verify);
1664
1665         obstack_free(&obst, NULL);
1666 }
1667
1668 /**
1669  * Initializes this module.
1670  */
1671 void be_init_straight_alloc(void)
1672 {
1673         static be_ra_t be_ra_straight = {
1674                 be_straight_alloc,
1675         };
1676
1677         FIRM_DBG_REGISTER(dbg, "firm.be.straightalloc");
1678
1679         be_register_allocator("straight", &be_ra_straight);
1680 }
1681
1682 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_straight_alloc);