nsz Git - libfirm/blob - ir/be/becopyilp2.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       ILP based copy minimization.
  23  * @author      Daniel Grund
  24  * @date        28.02.2006
  25  *
  26  * ILP formalization using G=(V, E, Q):
  27  *  - 2 class of variables: coloring vars x_ic   and   equal color vars y_ij
  28  *  - Path constraints
  29  *  - Clique-star constraints
  30  *
  31  *
  32  * \min \sum_{ (i,j) \in Q }  w_ij y_ij
  33  *
  34  *     \sum_c x_nc           =  1           n \in N, c \in C
  35  *
  36  *     x_nc                  =  0           n \in N, c \not\in C(n)
  37  *
  38  *     \sum x_nc            <=  1           x_nc \in Clique \in AllCliques,  c \in C
  39  *
  40  *     \sum_{e \in p} y_e   >=  1           p \in P      path constraints
  41  *
  42  *     \sum_{e \in cs} y_e  >= |cs| - 1     cs \in CP    clique-star constraints
  43  *
  44  *     x_nc, y_ij \in N,   w_ij \in R^+
  45  */
  46 #include "config.h"
  47
  48 #include "bitset.h"
  49 #include "raw_bitset.h"
  50 #include "pdeq.h"
  51
  52 #include "util.h"
  53 #include "irgwalk.h"
  54 #include "becopyilp_t.h"
  55 #include "beifg.h"
  56 #include "besched.h"
  57 #include "bemodule.h"
  58
  59 DEBUG_ONLY(static firm_dbg_module_t *dbg;)
  60
  61 typedef struct local_env_t {
  62         int             first_x_var;
  63         int             last_x_var;
  64         const unsigned *allocatable_colors;
  65 } local_env_t;
  66
  67 static unsigned check_alignment_constraints(ir_node *node)
  68 {
  69         const arch_register_req_t *req = arch_get_irn_register_req(node);
  70         // For larger than 1 variables, support only aligned constraints
  71         assert(((!(req->type & arch_register_req_type_aligned)
  72                          && req->width == 1)
  73                         || (req->type & arch_register_req_type_aligned))
  74                    && "Unaligned large (width > 1) variables not supported");
  75         return (req->type & arch_register_req_type_aligned) && req->width > 1;
  76 }
  77
  78 static void make_color_var_name(char *buf, size_t buf_size,
  79                                 const ir_node *node, unsigned color)
  80 {
  81         unsigned node_idx = get_irn_idx(node);
  82         snprintf(buf, buf_size, "x_%u_%u", node_idx, color);
  83 }
  84
  85 static void build_coloring_cstr(ilp_env_t *ienv)
  86 {
  87         local_env_t    *lenv   = (local_env_t*)ienv->env;
  88         be_ifg_t       *ifg    = ienv->co->cenv->ifg;
  89         unsigned        n_regs = arch_register_class_n_regs(ienv->co->cls);
  90         const unsigned *allocatable_colors = lenv->allocatable_colors;
  91         nodes_iter_t    iter;
  92         unsigned       *colors;
  93         ir_node        *irn;
  94         char            buf[32];
  95
  96         rbitset_alloca(colors, n_regs);
  97
  98         be_ifg_foreach_node(ifg, &iter, irn) {
  99                 const arch_register_req_t *req;
 100                 unsigned                   col;
 101                 int                        cst_idx;
 102                 unsigned                   curr_node_color;
 103                 unsigned                   has_alignment_cstr;
 104
 105                 if (sr_is_removed(ienv->sr, irn))
 106                         continue;
 107
 108                 has_alignment_cstr = check_alignment_constraints(irn);
 109
 110                 req = arch_get_irn_register_req(irn);
 111
 112                 /* get assignable colors */
 113                 if (arch_register_req_is(req, limited)) {
 114                         rbitset_copy(colors, req->limited, n_regs);
 115                 } else {
 116                         rbitset_copy(colors, allocatable_colors, n_regs);
 117                 }
 118
 119                 /* add the coloring constraint */
 120                 cst_idx = lpp_add_cst(ienv->lp, NULL, lpp_equal, 1.0);
 121
 122                 curr_node_color = get_irn_col(irn);
 123                 for (col = 0; col < n_regs; ++col) {
 124                         int    var_idx;
 125                         double val;
 126                         if (!rbitset_is_set(colors, col)
 127                                 || (has_alignment_cstr && ((col % req->width) != 0)))
 128                                 continue;
 129
 130                         make_color_var_name(buf, sizeof(buf), irn, col);
 131                         var_idx = lpp_add_var(ienv->lp, buf, lpp_binary, 0.0);
 132                         lpp_set_factor_fast(ienv->lp, cst_idx, var_idx, 1);
 133
 134                         val = (col == curr_node_color) ? 1.0 : 0.0;
 135                         lpp_set_start_value(ienv->lp, var_idx, val);
 136
 137                         lenv->last_x_var = var_idx;
 138                         if (lenv->first_x_var == -1)
 139                                 lenv->first_x_var = var_idx;
 140                 }
 141
 142                 /* add register constraint constraints */
 143                 for (col = 0; col < n_regs; ++col) {
 144                         int cst_idx;
 145                         int var_idx;
 146                         if (rbitset_is_set(colors, col)
 147                                 // for aligned variable, we set the unaligned part to 0
 148                                 && (!has_alignment_cstr || ((col % req->width) == 0)))
 149                                 continue;
 150
 151                         make_color_var_name(buf, sizeof(buf), irn, col);
 152                         cst_idx = lpp_add_cst(ienv->lp, NULL, lpp_equal, 0.0);
 153                         var_idx = lpp_add_var(ienv->lp, buf, lpp_binary, 0.0);
 154                         lpp_set_start_value(ienv->lp, var_idx, 0.0);
 155                         lpp_set_factor_fast(ienv->lp, cst_idx, var_idx, 1);
 156
 157                         lenv->last_x_var = var_idx;
 158                 }
 159         }
 160 }
 161
 162 static void build_interference_cstr(ilp_env_t *ienv)
 163 {
 164         lpp_t          *lpp      = ienv->lp;
 165         local_env_t    *lenv     = (local_env_t*)ienv->env;
 166         be_ifg_t       *ifg      = ienv->co->cenv->ifg;
 167         unsigned        n_colors = arch_register_class_n_regs(ienv->co->cls);
 168         ir_node       **clique   = ALLOCAN(ir_node*, n_colors);
 169         const unsigned *allocatable_colors = lenv->allocatable_colors;
 170         cliques_iter_t iter;
 171         int            size;
 172         unsigned       col;
 173         int            i;
 174
 175         /* for each maximal clique */
 176         be_ifg_foreach_clique(ifg, &iter, clique, &size) {
 177                 unsigned realsize = 0;
 178
 179                 for (i=0; i<size; ++i) {
 180                         if (!sr_is_removed(ienv->sr, clique[i]))
 181                                 ++realsize;
 182                 }
 183
 184                 if (realsize < 2)
 185                         continue;
 186
 187                 /* for all colors */
 188                 for (col=0; col<n_colors; ++col) {
 189                         int cst_idx;
 190                         if (!rbitset_is_set(allocatable_colors, col))
 191                                 continue;
 192
 193                         cst_idx = lpp_add_cst(lpp, NULL, lpp_less_equal, 1.0);
 194
 195                         /* for each member of this clique */
 196                         for (i=0; i<size; ++i) {
 197                                 ir_node *irn = clique[i];
 198                                 char     buf[32];
 199                                 int      var_idx;
 200                                 unsigned aligment_offset = 0;
 201
 202                                 if (sr_is_removed(ienv->sr, irn))
 203                                         continue;
 204
 205                                 // Use the first part of the large registers for all
 206                                 // interference, since it is the only colorable one.
 207                                 if (check_alignment_constraints(irn)) {
 208                                         const arch_register_req_t *req
 209                                                 = arch_get_irn_register_req(irn);
 210                                         aligment_offset = col % req->width;
 211                                 }
 212
 213                                 make_color_var_name(buf, sizeof(buf), irn,
 214                                                                         col - aligment_offset);
 215                                 var_idx = lpp_get_var_idx(lpp, buf);
 216                                 lpp_set_factor_fast(lpp, cst_idx, var_idx, 1);
 217                         }
 218                 }
 219         }
 220 }
 221
 222 static void make_affinity_var_name(char *buf, size_t buf_size,
 223                                    const ir_node *node1, const ir_node *node2)
 224 {
 225         unsigned n1 = get_irn_idx(node1);
 226         unsigned n2 = get_irn_idx(node2);
 227         if (n1 < n2) {
 228                 snprintf(buf, buf_size, "y_%u_%u", n1, n2);
 229         } else {
 230                 snprintf(buf, buf_size, "y_%u_%u", n2, n1);
 231         }
 232 }
 233
 234
 235 /**
 236  * TODO: Remove the dependency of the opt-units data structure
 237  *       by walking over all affinity edges. Graph structure
 238  *       does not provide this walker, yet.
 239  */
 240 static void build_affinity_cstr(ilp_env_t *ienv)
 241 {
 242         unsigned  n_colors = arch_register_class_n_regs(ienv->co->cls);
 243
 244         /* for all optimization units */
 245         list_for_each_entry(unit_t, curr, &ienv->co->units, units) {
 246                 ir_node *root     = curr->nodes[0];
 247                 unsigned root_col = get_irn_col(root);
 248                 int      i;
 249
 250                 for (i = 1; i < curr->node_count; ++i) {
 251                         ir_node *arg     = curr->nodes[i];
 252                         unsigned arg_col = get_irn_col(arg);
 253                         double   val;
 254                         char     buf[32];
 255                         unsigned col;
 256                         int      y_idx;
 257
 258                         /* add a new affinity variable */
 259                         make_affinity_var_name(buf, sizeof(buf), arg, root);
 260                         y_idx = lpp_add_var(ienv->lp, buf, lpp_binary, curr->costs[i]);
 261                         val   = (root_col == arg_col) ? 0.0 : 1.0;
 262                         lpp_set_start_value(ienv->lp, y_idx, val);
 263
 264                         /* add constraints relating the affinity var to the color vars */
 265                         for (col=0; col<n_colors; ++col) {
 266                                 int cst_idx = lpp_add_cst(ienv->lp, NULL, lpp_less_equal, 0.0);
 267                                 int root_idx;
 268                                 int arg_idx;
 269
 270                                 make_color_var_name(buf, sizeof(buf), root, col);
 271                                 root_idx = lpp_get_var_idx(ienv->lp, buf);
 272                                 make_color_var_name(buf, sizeof(buf), arg, col);
 273                                 arg_idx  = lpp_get_var_idx(ienv->lp, buf);
 274
 275                                 lpp_set_factor_fast(ienv->lp, cst_idx, root_idx,  1.0);
 276                                 lpp_set_factor_fast(ienv->lp, cst_idx, arg_idx,  -1.0);
 277                                 lpp_set_factor_fast(ienv->lp, cst_idx, y_idx, -1.0);
 278                         }
 279                 }
 280         }
 281 }
 282
 283 /**
 284  * Helping stuff for build_clique_star_cstr
 285  */
 286 typedef struct edge_t {
 287         ir_node *n1;
 288         ir_node *n2;
 289 } edge_t;
 290
 291 static int compare_edge_t(const void *k1, const void *k2, size_t size)
 292 {
 293         const edge_t *e1 = (const edge_t*)k1;
 294         const edge_t *e2 = (const edge_t*)k2;
 295         (void) size;
 296
 297         return ! (e1->n1 == e2->n1 && e1->n2 == e2->n2);
 298 }
 299
 300 #define HASH_EDGE(e) (hash_irn((e)->n1) ^ hash_irn((e)->n2))
 301
 302 static inline edge_t *add_edge(set *edges, ir_node *n1, ir_node *n2, size_t *counter)
 303 {
 304         edge_t new_edge;
 305
 306         if (PTR_TO_INT(n1) < PTR_TO_INT(n2)) {
 307                 new_edge.n1 = n1;
 308                 new_edge.n2 = n2;
 309         } else {
 310                 new_edge.n1 = n2;
 311                 new_edge.n2 = n1;
 312         }
 313         (*counter)++;
 314         return set_insert(edge_t, edges, &new_edge, sizeof(new_edge), HASH_EDGE(&new_edge));
 315 }
 316
 317 static inline edge_t *find_edge(set *edges, ir_node *n1, ir_node *n2)
 318 {
 319         edge_t new_edge;
 320
 321         if (PTR_TO_INT(n1) < PTR_TO_INT(n2)) {
 322                 new_edge.n1 = n1;
 323                 new_edge.n2 = n2;
 324         } else {
 325                 new_edge.n1 = n2;
 326                 new_edge.n2 = n1;
 327         }
 328         return set_find(edge_t, edges, &new_edge, sizeof(new_edge), HASH_EDGE(&new_edge));
 329 }
 330
 331 static inline void remove_edge(set *edges, ir_node *n1, ir_node *n2, size_t *counter)
 332 {
 333         edge_t new_edge, *e;
 334
 335         if (PTR_TO_INT(n1) < PTR_TO_INT(n2)) {
 336                 new_edge.n1 = n1;
 337                 new_edge.n2 = n2;
 338         } else {
 339                 new_edge.n1 = n2;
 340                 new_edge.n2 = n1;
 341         }
 342         e = set_find(edge_t, edges, &new_edge, sizeof(new_edge), HASH_EDGE(&new_edge));
 343         if (e) {
 344                 e->n1 = NULL;
 345                 e->n2 = NULL;
 346                 (*counter)--;
 347         }
 348 }
 349
 350 #define pset_foreach(pset, irn) foreach_pset((pset), ir_node, (irn))
 351
 352 /**
 353  * Search for an interference clique and an external node
 354  * with affinity edges to all nodes of the clique.
 355  * At most 1 node of the clique can be colored equally with the external node.
 356  */
 357 static void build_clique_star_cstr(ilp_env_t *ienv)
 358 {
 359         /* for each node with affinity edges */
 360         co_gs_foreach_aff_node(ienv->co, aff) {
 361                 struct obstack ob;
 362                 const ir_node *center = aff->irn;
 363                 ir_node **nodes;
 364                 set *edges;
 365                 int i, o, n_nodes;
 366                 size_t n_edges;
 367
 368                 if (arch_irn_is_ignore(aff->irn))
 369                         continue;
 370
 371                 obstack_init(&ob);
 372                 edges = new_set(compare_edge_t, 8);
 373
 374                 /* get all affinity neighbours */
 375                 n_nodes = 0;
 376                 co_gs_foreach_neighb(aff, nbr) {
 377                         if (!arch_irn_is_ignore(nbr->irn)) {
 378                                 obstack_ptr_grow(&ob, nbr->irn);
 379                                 ++n_nodes;
 380                         }
 381                 }
 382                 nodes = (ir_node**)obstack_finish(&ob);
 383
 384                 /* get all interference edges between these */
 385                 n_edges = 0;
 386                 for (i=0; i<n_nodes; ++i) {
 387                         for (o=0; o<i; ++o) {
 388                                 if (be_ifg_connected(ienv->co->cenv->ifg, nodes[i], nodes[o]))
 389                                         add_edge(edges, nodes[i], nodes[o], &n_edges);
 390                         }
 391                 }
 392
 393                 /* cover all these interference edges with maximal cliques */
 394                 while (n_edges) {
 395                         edge_t *e;
 396                         pset   *clique = pset_new_ptr(8);
 397                         bool    growed;
 398
 399                         /* get 2 starting nodes to form a clique */
 400                         for (e = set_first(edge_t, edges); !e->n1; e = set_next(edge_t, edges)) {}
 401
 402                         /* we could be stepped out of the loop before the set iterated to the end */
 403                         set_break(edges);
 404
 405                         pset_insert_ptr(clique, e->n1);
 406                         pset_insert_ptr(clique, e->n2);
 407                         remove_edge(edges, e->n1, e->n2, &n_edges);
 408
 409                         /* while the clique is growing */
 410                         do {
 411                                 growed = false;
 412
 413                                 /* search for a candidate to extend the clique */
 414                                 for (i=0; i<n_nodes; ++i) {
 415                                         ir_node *cand = nodes[i];
 416                                         bool     is_cand;
 417
 418                                         /* if its already in the clique try the next */
 419                                         if (pset_find_ptr(clique, cand))
 420                                                 continue;
 421
 422                                         /* are there all necessary interferences? */
 423                                         is_cand = true;
 424                                         pset_foreach(clique, member) {
 425                                                 if (!find_edge(edges, cand, member)) {
 426                                                         is_cand = false;
 427                                                         pset_break(clique);
 428                                                         break;
 429                                                 }
 430                                         }
 431
 432                                         /* now we know if we have a clique extender */
 433                                         if (is_cand) {
 434                                                 /* first remove all covered edges */
 435                                                 pset_foreach(clique, member)
 436                                                         remove_edge(edges, cand, member, &n_edges);
 437
 438                                                 /* insert into clique */
 439                                                 pset_insert_ptr(clique, cand);
 440                                                 growed = true;
 441                                                 break;
 442                                         }
 443                                 }
 444                         } while (growed);
 445
 446                         /* now the clique is maximal. Finally add the constraint */
 447                         {
 448                                 int  var_idx;
 449                                 int  cst_idx;
 450                                 char buf[32];
 451
 452                                 cst_idx = lpp_add_cst(ienv->lp, NULL, lpp_greater_equal, pset_count(clique)-1);
 453
 454                                 pset_foreach(clique, member) {
 455                                         make_affinity_var_name(buf, sizeof(buf), center, member);
 456                                         var_idx = lpp_get_var_idx(ienv->lp, buf);
 457                                         lpp_set_factor_fast(ienv->lp, cst_idx, var_idx, 1.0);
 458                                 }
 459                         }
 460
 461                         del_pset(clique);
 462                 }
 463
 464                 del_set(edges);
 465                 obstack_free(&ob, NULL);
 466         }
 467 }
 468
 469 static void extend_path(ilp_env_t *ienv, pdeq *path, const ir_node *irn)
 470 {
 471         be_ifg_t *ifg = ienv->co->cenv->ifg;
 472         int i, len;
 473         ir_node **curr_path;
 474         affinity_node_t *aff;
 475
 476         /* do not walk backwards or in circles */
 477         if (pdeq_contains(path, irn))
 478                 return;
 479
 480         if (arch_irn_is_ignore(irn))
 481                 return;
 482
 483         /* insert the new irn */
 484         pdeq_putr(path, irn);
 485
 486         /* check for forbidden interferences */
 487         len       = pdeq_len(path);
 488         curr_path = ALLOCAN(ir_node*, len);
 489         pdeq_copyl(path, (const void **)curr_path);
 490
 491         for (i=1; i<len; ++i) {
 492                 if (be_ifg_connected(ifg, irn, curr_path[i]))
 493                         goto end;
 494         }
 495
 496         /* check for terminating interference */
 497         if (be_ifg_connected(ifg, irn, curr_path[0])) {
 498                 /* One node is not a path. */
 499                 /* And a path of length 2 is covered by a clique star constraint. */
 500                 if (len > 2) {
 501                         /* finally build the constraint */
 502                         int cst_idx = lpp_add_cst(ienv->lp, NULL, lpp_greater_equal, 1.0);
 503                         for (i=1; i<len; ++i) {
 504                                 char buf[32];
 505                                 int  var_idx;
 506
 507                                 make_affinity_var_name(buf, sizeof(buf), curr_path[i-1], curr_path[i]);
 508                                 var_idx = lpp_get_var_idx(ienv->lp, buf);
 509                                 lpp_set_factor_fast(ienv->lp, cst_idx, var_idx, 1.0);
 510                         }
 511                 }
 512
 513                 /* this path cannot be extended anymore */
 514                 goto end;
 515         }
 516
 517         /* recursively extend the path */
 518         aff = get_affinity_info(ienv->co, irn);
 519         co_gs_foreach_neighb(aff, nbr) {
 520                 extend_path(ienv, path, nbr->irn);
 521         }
 522
 523 end:
 524         /* remove the irn */
 525         pdeq_getr(path);
 526 }
 527
 528 /**
 529  * Search a path of affinity edges, whose ends are connected
 530  * by an interference edge and there are no other interference
 531  * edges in between.
 532  * Then at least one of these affinity edges must break.
 533  */
 534 static void build_path_cstr(ilp_env_t *ienv)
 535 {
 536         /* for each node with affinity edges */
 537         co_gs_foreach_aff_node(ienv->co, aff_info) {
 538                 pdeq *path = new_pdeq();
 539
 540                 extend_path(ienv, path, aff_info->irn);
 541
 542                 del_pdeq(path);
 543         }
 544 }
 545
 546 static void ilp2_build(ilp_env_t *ienv)
 547 {
 548         int lower_bound;
 549
 550         ienv->lp = lpp_new(ienv->co->name, lpp_minimize);
 551         build_coloring_cstr(ienv);
 552         build_interference_cstr(ienv);
 553         build_affinity_cstr(ienv);
 554         build_clique_star_cstr(ienv);
 555         build_path_cstr(ienv);
 556
 557         lower_bound = co_get_lower_bound(ienv->co) - co_get_inevit_copy_costs(ienv->co);
 558         lpp_set_bound(ienv->lp, lower_bound);
 559 }
 560
 561 static void ilp2_apply(ilp_env_t *ienv)
 562 {
 563         local_env_t *lenv = (local_env_t*)ienv->env;
 564         ir_graph    *irg  = ienv->co->irg;
 565
 566         /* first check if there was sth. to optimize */
 567         if (lenv->first_x_var >= 0) {
 568                 int              count = lenv->last_x_var - lenv->first_x_var + 1;
 569                 double          *sol   = XMALLOCN(double, count);
 570                 lpp_sol_state_t  state = lpp_get_solution(ienv->lp, sol, lenv->first_x_var, lenv->last_x_var);
 571                 int              i;
 572
 573                 if (state != lpp_optimal) {
 574                         printf("WARNING %s: Solution state is not 'optimal': %d\n",
 575                                ienv->co->name, (int)state);
 576                         if (state < lpp_feasible) {
 577                                 panic("Copy coalescing solution not feasible!");
 578                         }
 579                 }
 580
 581                 for (i=0; i<count; ++i) {
 582                         unsigned nodenr;
 583                         unsigned color;
 584                         char     var_name[32];
 585                         if (sol[i] <= 1-EPSILON)
 586                                 continue;
 587                         /* split variable name into components */
 588                         lpp_get_var_name(ienv->lp, lenv->first_x_var+i, var_name, sizeof(var_name));
 589
 590                         if (sscanf(var_name, "x_%u_%u", &nodenr, &color) == 2) {
 591                                 ir_node *irn = get_idx_irn(irg, nodenr);
 592                                 set_irn_col(ienv->co->cls, irn, color);
 593                         } else {
 594                                 panic("This should be a x-var");
 595                         }
 596                 }
 597
 598                 xfree(sol);
 599         }
 600
 601 #ifdef COPYOPT_STAT
 602         /* TODO adapt to multiple possible ILPs */
 603         copystat_add_ilp_time((int)(1000.0*lpp_get_sol_time(pi->curr_lp)));  //now we have ms
 604         copystat_add_ilp_vars(lpp_get_var_count(pi->curr_lp));
 605         copystat_add_ilp_csts(lpp_get_cst_count(pi->curr_lp));
 606         copystat_add_ilp_iter(lpp_get_iter_cnt(pi->curr_lp));
 607 #endif
 608 }
 609
 610 /**
 611  * Solves the problem using mixed integer programming
 612  * @returns 1 iff solution state was optimal
 613  * Uses the OU and the GRAPH data structure
 614  * Dependency of the OU structure can be removed
 615  */
 616 static int co_solve_ilp2(copy_opt_t *co)
 617 {
 618         unsigned       *allocatable_colors;
 619         unsigned        n_regs = arch_register_class_n_regs(co->cls);
 620         lpp_sol_state_t sol_state;
 621         ilp_env_t      *ienv;
 622         local_env_t     my;
 623
 624         ASSERT_OU_AVAIL(co); //See build_clique_st
 625         ASSERT_GS_AVAIL(co);
 626
 627         my.first_x_var = -1;
 628         my.last_x_var  = -1;
 629         FIRM_DBG_REGISTER(dbg, "firm.be.coilp2");
 630
 631         rbitset_alloca(allocatable_colors, n_regs);
 632         be_set_allocatable_regs(co->irg, co->cls, allocatable_colors);
 633         my.allocatable_colors = allocatable_colors;
 634
 635         ienv = new_ilp_env(co, ilp2_build, ilp2_apply, &my);
 636
 637         sol_state = ilp_go(ienv);
 638
 639         free_ilp_env(ienv);
 640
 641         return sol_state == lpp_optimal;
 642 }
 643
 644 BE_REGISTER_MODULE_CONSTRUCTOR(be_init_copyilp2)
 645 void be_init_copyilp2(void)
 646 {
 647         static co_algo_info copyheur = {
 648                 co_solve_ilp2, 1
 649         };
 650
 651         be_register_copyopt("ilp", &copyheur);
 652 }