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