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

   1 /**
   2  * Implements a list scheduler for the MRIS algorithm in:
   3  * Govindarajan, Yang, Amaral, Zhang, Gao
   4  * Minimum Register Instruction Sequencing to Reduce Register Spills
   5  * in out-of-order issue superscalar architectures
   6  * @author Sebastian Hack
   7  * @date   04.04.2006
   8  */
   9
  10 #include <limits.h>
  11
  12 #include "misc.h"
  13 #include "obstack.h"
  14 #include "debug.h"
  15
  16 #include "irgraph_t.h"
  17 #include "irnode_t.h"
  18 #include "iredges_t.h"
  19 #include "ircons_t.h"
  20 #include "irgwalk.h"
  21 #include "irtools.h"
  22
  23 #include "benode_t.h"
  24 #include "besched_t.h"
  25 #include "beschedmris.h"
  26
  27 struct _mris_env_t {
  28         firm_dbg_module_t *dbg;
  29         const arch_env_t  *aenv;
  30         ir_graph          *irg;
  31         ir_node           *bl;
  32         nodeset           *inserted;
  33         int               visited;
  34         struct list_head  lineage_head;
  35         struct obstack    obst;
  36 };
  37
  38 typedef struct _mris_irn_t {
  39         int visited;
  40         int height;
  41         ir_node *lineage_start;
  42         ir_node *lineage_next;
  43         ir_node *lineage_end;
  44         struct list_head lineage_list;
  45 } mris_irn_t;
  46
  47 #define to_appear(env, irn) (to_appear_in_schedule(irn) && get_nodes_block(irn) == env->bl)
  48
  49 #define get_irn_height(env, irn) (get_mris_irn(env, irn)->height)
  50 #define foreach_lineage(env, pos, tmp) list_for_each_entry_safe(mris_irn_t, pos, tmp, &(env)->lineage_head, lineage_list)
  51
  52 static mris_irn_t *get_mris_irn(mris_env_t *env, ir_node *irn)
  53 {
  54         mris_irn_t *mi = get_irn_link(irn);
  55
  56         if(!mi) {
  57                 mi = obstack_alloc(&env->obst, sizeof(mi[0]));
  58                 memset(mi, 0, sizeof(mi[0]));
  59                 set_irn_link(irn, mi);
  60                 INIT_LIST_HEAD(&mi->lineage_list);
  61         }
  62
  63         return mi;
  64 }
  65
  66 static int compute_height(mris_env_t *env, ir_node *irn, unsigned long visited)
  67 {
  68         mris_irn_t *mi = get_mris_irn(env, irn);
  69
  70         if(get_irn_visited(irn) >= visited) {
  71                 DBG((env->dbg, LEVEL_3, "\theight of %+F = %d\n", irn, mi->height));
  72                 return mi->height;
  73         }
  74
  75         else {
  76                 const ir_edge_t *edge;
  77
  78                 set_irn_visited(irn, visited);
  79                 mi->height  = 0;
  80
  81                 foreach_out_edge(irn, edge) {
  82                         ir_node *dep = get_edge_src_irn(edge);
  83
  84                         if(!is_Block(dep) && get_nodes_block(dep) == env->bl) {
  85                                 int dep_height = compute_height(env, dep, visited);
  86                                 mi->height     = MAX(mi->height, dep_height);
  87                         }
  88                 }
  89
  90                 mi->height++;
  91                 DBG((env->dbg, LEVEL_3, "\tsetting height of %+F = %d\n", irn, mi->height));
  92         }
  93
  94         return mi->height;
  95 }
  96
  97 static void compute_heights(mris_env_t *env)
  98 {
  99         const ir_edge_t *edge;
 100         unsigned long visited;
 101
 102         visited = get_irg_visited(env->irg) + 1;
 103         set_irg_visited(env->irg, visited);
 104
 105         foreach_out_edge(env->bl, edge) {
 106                 ir_node *dep = get_edge_src_irn(edge);
 107                 if(to_appear(env, dep))
 108                         compute_height(env, dep, visited);
 109         }
 110 }
 111
 112 #define valid_node(env, dep) (to_appear(env, dep) && !nodeset_find(env->inserted, dep) && !be_is_Keep(dep))
 113
 114 static void grow_all_descendands(mris_env_t *env, ir_node *irn, unsigned long visited)
 115 {
 116         const ir_edge_t *edge;
 117
 118         assert(get_irn_mode(irn) != mode_T);
 119
 120         foreach_out_edge(irn, edge) {
 121                 ir_node *desc = get_edge_src_irn(edge);
 122                 if(valid_node(env, desc) && get_irn_visited(desc) < visited) {
 123                         obstack_ptr_grow(&env->obst, desc);
 124                         set_irn_visited(desc, visited);
 125                 }
 126         }
 127 }
 128
 129 static ir_node **all_descendants(mris_env_t *env, ir_node *irn)
 130 {
 131         unsigned long visited;
 132         const ir_edge_t *edge;
 133
 134         visited = get_irg_visited(env->irg) + 1;
 135         set_irg_visited(env->irg, visited);
 136
 137         if(get_irn_mode(irn) == mode_T) {
 138                 foreach_out_edge(irn, edge) {
 139                         ir_node *desc = get_edge_src_irn(edge);
 140                         assert(is_Proj(desc) && get_irn_mode(desc) != mode_T);
 141                         grow_all_descendands(env, desc, visited);
 142                 }
 143         }
 144
 145         else
 146                 grow_all_descendands(env, irn, visited);
 147
 148         obstack_ptr_grow(&env->obst, NULL);
 149         return obstack_finish(&env->obst);
 150 }
 151
 152 static ir_node *put_lowest_in_front(mris_env_t *env, ir_node **in)
 153 {
 154         int lowest_index  = 0;
 155         int lowest_height = INT_MAX;
 156         int i;
 157
 158         for(i = 0; in[i]; ++i) {
 159                 mris_irn_t *mi = get_mris_irn(env, in[i]);
 160                 if(mi->height < lowest_height) {
 161                         lowest_height = mi->height;
 162                         lowest_index  = i;
 163                 }
 164         }
 165
 166         if(i > 0) {
 167                 ir_node *tmp     = in[0];
 168                 in[0]            = in[lowest_index];
 169                 in[lowest_index] = tmp;
 170         }
 171
 172         return in[0];
 173 }
 174
 175 static void reaches_walker(mris_env_t *env, ir_node *irn, ir_node *tgt, int *found, unsigned long visited)
 176 {
 177         if(get_irn_visited(irn) < visited && get_nodes_block(irn) == env->bl) {
 178
 179                 set_irn_visited(irn, visited);
 180
 181                 if(irn == tgt)
 182                         *found = 1;
 183                 else {
 184                         int i, n;
 185
 186                         for(i = 0, n = get_irn_arity(irn); i < n; ++i) {
 187                                 ir_node *op = get_irn_n(irn, i);
 188                                 if(!*found)
 189                                         reaches_walker(env, op, tgt, found, visited);
 190                         }
 191                 }
 192         }
 193 }
 194
 195 static int reaches(mris_env_t *env, ir_node *src, ir_node *tgt)
 196 {
 197         int found = 0;
 198         unsigned long visited = get_irg_visited(env->irg) + 1;
 199
 200         set_irg_visited(env->irg, visited);
 201         reaches_walker(env, src, tgt, &found, visited);
 202         return found;
 203 }
 204
 205 static INLINE ir_node *skip_Projs(ir_node *irn)
 206 {
 207         return is_Proj(irn) ? skip_Projs(get_Proj_pred(irn)) : irn;
 208 }
 209
 210 static void replace_tuple_by_repr_proj(mris_env_t *env, ir_node **in)
 211 {
 212         int i;
 213
 214         for(i = 0; in[i]; ++i) {
 215                 if(get_irn_mode(in[i]) == mode_T) {
 216                         const ir_edge_t *edge;
 217                         ir_node *proj  = NULL;
 218                         ir_node *first = NULL;
 219
 220                         foreach_out_edge(in[i], edge) {
 221                                 ir_node *desc = get_edge_src_irn(edge);
 222
 223                                 first = first ? first : desc;
 224                                 if(get_irn_mode(desc) == mode_M) {
 225                                         proj = desc;
 226                                         break;
 227                                 }
 228                         }
 229
 230                         proj = proj ? proj : first;
 231                         assert(proj);
 232                         in[i] = proj;
 233                 }
 234         }
 235 }
 236
 237 static void lineage_formation(mris_env_t *env)
 238 {
 239         firm_dbg_module_t *dbg = env->dbg;
 240         nodeset *nodes         = new_nodeset(128);
 241
 242         const ir_edge_t *edge;
 243
 244         foreach_out_edge(env->bl, edge) {
 245                 ir_node *irn = get_edge_src_irn(edge);
 246                 if(to_appear(env, irn))
 247                         nodeset_insert(nodes, irn);
 248         }
 249
 250         compute_heights(env);
 251
 252         while(nodeset_count(nodes) > 0) {
 253                 mris_irn_t *mi;
 254                 ir_node *irn;
 255                 ir_node *highest_node = NULL;
 256                 ir_node *lowest_desc  = NULL;
 257
 258                 ir_node **in;
 259                 int recompute_height  = 0;
 260                 int curr_height       = 0;
 261
 262                 /* search the highest node which is not yet in a lineage. */
 263                 for(irn = nodeset_first(nodes); irn; irn = nodeset_next(nodes)) {
 264                         mris_irn_t *inf = get_mris_irn(env, irn);
 265                         if(inf->height > curr_height) {
 266                                 highest_node = irn;
 267                                 curr_height  = inf->height;
 268                         }
 269                 }
 270
 271                 assert(highest_node);
 272                 DBG((dbg, LEVEL_2, "highest node is %+F height %d\n", highest_node, get_irn_height(env, highest_node)));
 273
 274                 /* start a lineage beginning with highest_node. */
 275                 mi = get_mris_irn(env, highest_node);
 276                 mi->lineage_start = highest_node;
 277                 mi->lineage_next  = NULL;
 278                 mi->lineage_end   = NULL;
 279                 list_add(&mi->lineage_list, &env->lineage_head);
 280                 nodeset_remove(nodes, highest_node);
 281
 282                 /*
 283                         put all descendants in an array.
 284                         we also move the lowest descendant in front, so that the other nodes
 285                         are easily accessible as an array, too.
 286                 */
 287                 in          = all_descendants(env, highest_node);
 288                 lowest_desc = put_lowest_in_front(env, in);
 289
 290                 /* as long as the current highest node has still descendants */
 291                 while(lowest_desc) {
 292                         mris_irn_t *lowest_mi  = get_mris_irn(env, lowest_desc);
 293                         mris_irn_t *highest_mi = get_mris_irn(env, highest_node);
 294                         mris_irn_t *start_mi   = get_mris_irn(env, highest_mi->lineage_start);
 295                         int highest_is_tuple   = get_irn_mode(highest_node) == mode_T;
 296
 297                         int n_desc;
 298
 299                         DBG((dbg, LEVEL_2, "\tlowest descendant %+F height %d\n", lowest_desc, mi->height));
 300
 301                         /* count the number of all descendants which are not the lowest descendant */
 302                         for(n_desc = 0; in[n_desc + 1]; ++n_desc);
 303
 304                         /*
 305                         we insert a CopyKeep node to express the artificial dependencies from the lowest
 306                         descendant to all other descendants.
 307                         */
 308                         if(n_desc > 1 && !be_is_Keep(lowest_desc)) {
 309                                 const arch_register_class_t *cls;
 310                                 ir_node *copy_keep, *op;
 311                                 int i, n;
 312
 313                                 for(i = 0, n = get_irn_arity(lowest_desc); i < n; ++i) {
 314                                         ir_node *cmp;
 315
 316                                         op  = get_irn_n(lowest_desc, i);
 317                                         cmp = highest_is_tuple ? skip_Projs(op) : op;
 318
 319                                         if(cmp == highest_node)
 320                                                 break;
 321                                 }
 322
 323                                 assert(i < n && "could not find operand");
 324
 325                                 cls = arch_get_irn_reg_class(env->aenv, op, BE_OUT_POS(0));
 326                                 replace_tuple_by_repr_proj(env, &in[1]);
 327                                 copy_keep = be_new_CopyKeep(cls, env->irg, env->bl, op, n_desc, &in[1], get_irn_mode(op));
 328                                 set_irn_n(lowest_desc, i, copy_keep);
 329                                 nodeset_insert(env->inserted, copy_keep);
 330                         }
 331                         obstack_free(&env->obst, in);
 332
 333                         /* mark the current lowest node as the last one in the lineage. */
 334                         highest_mi->lineage_next = lowest_desc;
 335                         start_mi->lineage_end    = lowest_desc;
 336
 337                         /* if the current lowest node is not yet in a lineage, add it to the current one. */
 338                         if(!lowest_mi->lineage_start) {
 339                                 lowest_mi->lineage_start = highest_mi->lineage_start;
 340                                 nodeset_remove(nodes, lowest_desc);
 341                         }
 342
 343                         /* else we cannot extend this lineage, so break. */
 344                         else
 345                                 break;
 346
 347                         highest_node = lowest_desc;
 348                         highest_mi   = lowest_mi;
 349
 350                         /* recompute the descendants array and the new lowest descendant. */
 351                         in          = all_descendants(env, highest_node);
 352                         lowest_desc = put_lowest_in_front(env, in);
 353                 }
 354
 355                 /* recompute the heights if desired. */
 356                 if(recompute_height)
 357                         compute_heights(env);
 358         }
 359 }
 360
 361 static int fuse_two_lineages(mris_env_t *env, mris_irn_t *u, mris_irn_t *v)
 362 {
 363         mris_irn_t *mi;
 364         mris_irn_t *copy_mi;
 365         ir_node *irn, *last, *copy;
 366         ir_node *u_end   = u->lineage_end;
 367         ir_node *v_start = v->lineage_start;
 368         ir_node *start   = skip_Projs(v_start);
 369
 370         if(be_is_Keep(start))
 371                 return 0;
 372
 373         /* set lineage end of nodes in u to end of v. */
 374         irn = last = u->lineage_start;
 375         mi         = get_mris_irn(env, irn);
 376         while(irn != u_end) {
 377                 mi = get_mris_irn(env, irn);
 378                 mi->lineage_end = v->lineage_end;
 379                 last = irn;
 380                 irn = mi->lineage_next;
 381         }
 382
 383         /* insert a CopyKeep to make lineage v dependent on u. */
 384         {
 385                 const arch_register_class_t *cls;
 386                 ir_node *op    = NULL;
 387                 int i, n;
 388
 389                 if(get_irn_arity(start) == 0)
 390                         return 0;
 391
 392                 op = get_irn_n(start, 0);
 393
 394                 cls  = arch_get_irn_reg_class(env->aenv, op, BE_OUT_POS(0));
 395                 if(get_irn_mode(last) == mode_T) {
 396                         const ir_edge_t *edge;
 397                         foreach_out_edge(last, edge) {
 398                                 last = get_edge_src_irn(edge);
 399                                 break;
 400                         }
 401                 }
 402                 copy = be_new_CopyKeep_single(cls, env->irg, env->bl, op, last, get_irn_mode(op));
 403                 set_irn_n(start, 0, copy);
 404                 copy_mi = get_mris_irn(env, copy);
 405                 nodeset_insert(env->inserted, copy);
 406         }
 407
 408         /* irn now points to the last node in lineage u; mi has the info for the node _before_ the terminator of the lineage. */
 409         mi->lineage_next       = copy;
 410         copy_mi->lineage_start = u->lineage_start;
 411         copy_mi->lineage_end   = v->lineage_end;
 412         copy_mi->lineage_next  = v_start;
 413
 414         /* set lineage start of nodes in v to start of u. */
 415         irn = v->lineage_start;
 416         while(irn != v->lineage_end) {
 417                 mris_irn_t *mi = get_mris_irn(env, irn);
 418                 mi->lineage_start = u->lineage_start;
 419                 irn = mi->lineage_next;
 420         }
 421
 422         mi = get_mris_irn(env, v_start);
 423         list_del(&mi->lineage_list);
 424
 425         return 1;
 426 }
 427
 428 static void fuse_lineages(mris_env_t *env)
 429 {
 430         int fused = 1;
 431         mris_irn_t *u, *v, *tmp1, *tmp2;
 432
 433 again:
 434         foreach_lineage(env, u, tmp1) {
 435                 foreach_lineage(env, v, tmp2) {
 436                         if(u == v)
 437                                 continue;
 438
 439                         if(!reaches(env, u->lineage_start, v->lineage_end) && reaches(env, v->lineage_start, u->lineage_end)) {
 440                                 if(fuse_two_lineages(env, u, v))
 441                                         goto again;
 442                         }
 443                 }
 444         }
 445 }
 446
 447 static void block_walker(ir_node *bl, void *data)
 448 {
 449         mris_env_t *env = data;
 450         env->bl = bl;
 451         lineage_formation(env);
 452         fuse_lineages(env);
 453 }
 454
 455
 456 mris_env_t *be_sched_mris_preprocess(const be_irg_t *birg)
 457 {
 458         mris_env_t *env = xmalloc(sizeof(env[0]));
 459
 460         env->aenv     = birg->main_env->arch_env;
 461         env->irg      = birg->irg;
 462         env->visited  = 0;
 463         env->inserted = new_nodeset(128);
 464         INIT_LIST_HEAD(&env->lineage_head);
 465         FIRM_DBG_REGISTER(env->dbg, "firm.be.sched.mris");
 466         obstack_init(&env->obst);
 467         irg_walk_graph(env->irg, firm_clear_link, NULL, NULL);
 468         irg_block_walk_graph(birg->irg, block_walker, NULL, env);
 469         obstack_free(&env->obst, NULL);
 470         return env;
 471 }
 472
 473 static void cleanup_inserted(mris_env_t *env)
 474 {
 475         ir_node *irn;
 476
 477         for(irn = nodeset_first(env->inserted); irn; irn = nodeset_next(env->inserted)) {
 478                 int i, n;
 479                 ir_node *tgt;
 480
 481                 assert(be_is_CopyKeep(irn));
 482                 tgt = get_irn_n(irn, be_pos_CopyKeep_op);
 483
 484                 /* reroute the edges, remove from schedule and make it invisible. */
 485                 edges_reroute(irn, tgt, env->irg);
 486                 sched_remove(irn);
 487                 for(i = -1, n = get_irn_arity(irn); i < n; ++i)
 488                         set_irn_n(irn, i, new_r_Bad(env->irg));
 489         }
 490 }
 491
 492 void be_sched_mris_free(mris_env_t *env)
 493 {
 494         cleanup_inserted(env);
 495         del_nodeset(env->inserted);
 496         free(env);
 497 }