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

   1 /*
   2  * Author:      Matthias Braun
   3  * Date:                05.05.2006
   4  * Copyright:   (c) Universitaet Karlsruhe
   5  * License:     This file is protected by GPL -  GNU GENERAL PUBLIC LICENSE.
   6  *
   7  */
   8 #ifdef HAVE_CONFIG_H
   9 #include "config.h"
  10 #endif
  11
  12 #include "bespillmorgan.h"
  13
  14 #include "bechordal_t.h"
  15 #include "bespill.h"
  16 #include "belive_t.h"
  17 #include "beabi.h"
  18 #include "irgwalk.h"
  19 #include "besched.h"
  20 #include "beutil.h"
  21 #include "irloop_t.h"
  22 #include "irgraph_t.h"
  23 #include "irprintf.h"
  24 #include "obstack.h"
  25
  26 #include "bespillbelady.h"
  27 #include "beverify.h"
  28 #include "benodesets.h"
  29
  30 #define DBG_LIVE                1
  31 #define DBG_LOOPANA             2
  32 #define DBG_PRESSURE    4
  33 #define DBG_SPILLS      8
  34 DEBUG_ONLY(static firm_dbg_module_t *dbg = NULL;)
  35
  36 typedef struct morgan_env {
  37         const be_chordal_env_t *cenv;
  38         const arch_env_t *arch;
  39         const arch_register_class_t *cls;
  40         ir_graph *irg;
  41         struct obstack obst;
  42         /** maximum safe register pressure */
  43         int registers_available;
  44
  45         spill_env_t *senv;
  46
  47         set *loop_attr_set;
  48         set *block_attr_set;
  49 } morgan_env_t;
  50
  51 typedef struct loop_edge {
  52         ir_node *block;
  53         int pos;
  54 } loop_edge_t;
  55
  56 typedef struct loop_attr {
  57         const ir_loop *loop;
  58         set *out_edges;
  59         set *in_edges;
  60         /** The set of all values that are live in the loop but not used in the loop */
  61         bitset_t *livethrough_unused;
  62 } loop_attr_t;
  63
  64 typedef struct block_attr {
  65         const ir_node *block;
  66         /** set of all values that are live in the block but not used in the block */
  67         bitset_t *livethrough_unused;
  68 } block_attr_t;
  69
  70 //---------------------------------------------------------------------------
  71
  72 static int loop_edge_cmp(const void* p1, const void* p2, size_t s) {
  73         loop_edge_t *e1 = (loop_edge_t*) p1;
  74         loop_edge_t *e2 = (loop_edge_t*) p2;
  75
  76         return e1->block != e2->block || e1->pos != e2->pos;
  77 }
  78
  79 static int loop_attr_cmp(const void *e1, const void *e2, size_t s) {
  80         loop_attr_t *la1 = (loop_attr_t*) e1;
  81         loop_attr_t *la2 = (loop_attr_t*) e2;
  82
  83         return la1->loop != la2->loop;
  84 }
  85
  86 static int block_attr_cmp(const void *e1, const void *e2, size_t s) {
  87         block_attr_t *b1 = (block_attr_t*) e1;
  88         block_attr_t *b2 = (block_attr_t*) e2;
  89
  90         return b1->block != b2->block;
  91 }
  92
  93 static INLINE int loop_attr_hash(const loop_attr_t *a) {
  94 #ifdef DEBUG_libfirm
  95         return a->loop->loop_nr;
  96 #else
  97         return HASH_PTR(a->loop);
  98 #endif
  99 }
 100
 101 static INLINE int block_attr_hash(const block_attr_t *b) {
 102         return nodeset_hash(b->block);
 103 }
 104
 105 static INLINE int loop_edge_hash(const loop_edge_t *e) {
 106         return nodeset_hash(e->block) ^ (e->pos * 31);
 107 }
 108
 109 static INLINE loop_attr_t *get_loop_attr(morgan_env_t *env, const ir_loop *loop) {
 110         loop_attr_t l_attr, *res;
 111         int hash;
 112         l_attr.loop = loop;
 113
 114         hash = loop_attr_hash(&l_attr);
 115         res = set_find(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
 116
 117         // create new loop_attr if none exists yet
 118         if (res == NULL) {
 119                 l_attr.out_edges = new_set(loop_edge_cmp, 1);
 120                 l_attr.in_edges = new_set(loop_edge_cmp, 1);
 121                 l_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
 122                 res = set_insert(env->loop_attr_set, &l_attr, sizeof(l_attr), hash);
 123         }
 124
 125         return res;
 126 }
 127
 128 static INLINE block_attr_t *get_block_attr(morgan_env_t *env, const ir_node *block) {
 129         block_attr_t b_attr, *res;
 130         int hash;
 131         b_attr.block = block;
 132
 133         hash = block_attr_hash(&b_attr);
 134         res = set_find(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
 135
 136         if(res == NULL) {
 137                 b_attr.livethrough_unused = bitset_obstack_alloc(&env->obst, get_irg_last_idx(env->irg));
 138                 res = set_insert(env->block_attr_set, &b_attr, sizeof(b_attr), hash);
 139         }
 140
 141         return res;
 142 }
 143
 144 //---------------------------------------------------------------------------
 145
 146 static INLINE int consider_for_spilling(const arch_env_t *env, const arch_register_class_t *cls, const ir_node *node) {
 147         if(!arch_irn_has_reg_class(env, node, -1, cls))
 148                 return 0;
 149
 150         return !(arch_irn_get_flags(env, node) & (arch_irn_flags_ignore | arch_irn_flags_dont_spill));
 151 }
 152
 153 /**
 154  * Determine edges going out of a loop (= edges that go to a block that is not inside
 155  * the loop or one of its subloops)
 156  */
 157 static INLINE void construct_loop_edges(ir_node* block, void* data) {
 158         morgan_env_t *env = data;
 159         int n_cfgpreds = get_Block_n_cfgpreds(block);
 160         int i;
 161         ir_loop* loop = get_irn_loop(block);
 162         DBG((dbg, DBG_LOOPANA, "Loop for %+F: %d (depth %d)\n", block, loop->loop_nr, loop->depth));
 163
 164         for(i = 0; i < n_cfgpreds; ++i) {
 165                 loop_edge_t edge;
 166                 int hash;
 167                 ir_node* cfgpred = get_Block_cfgpred(block, i);
 168                 ir_node* cfgpred_block = get_nodes_block(cfgpred);
 169                 ir_loop* cfgpred_loop = get_irn_loop(cfgpred_block);
 170
 171                 if(cfgpred_loop == loop)
 172                         continue;
 173
 174                 assert(get_loop_depth(cfgpred_loop) != get_loop_depth(loop));
 175
 176                 edge.block = block;
 177                 edge.pos = i;
 178                 hash = loop_edge_hash(&edge);
 179
 180                 // edge out of a loop?
 181                 if(get_loop_depth(cfgpred_loop) > get_loop_depth(loop)) {
 182                         ir_loop *l;
 183
 184                         DBG((dbg, DBG_LOOPANA, "Loop out edge from %+F (loop %d) to %+F (loop %d)\n", block, get_loop_loop_nr(loop),
 185                              cfgpred_block, get_loop_loop_nr(cfgpred_loop)));
 186
 187                         /* this might be a jump out of multiple loops, so add this to all
 188                      * needed outedge sets */
 189                         l = cfgpred_loop;
 190                         do {
 191                                 loop_attr_t *l_attr = get_loop_attr(env, l);
 192                                 set_insert(l_attr->out_edges, &edge, sizeof(edge), hash);
 193
 194                                 l = get_loop_outer_loop(l);
 195                                 assert(l != NULL);
 196                         } while(l != loop);
 197                 } else {
 198                         ir_loop *l;
 199
 200                         // edge into a loop
 201                         DBG((dbg, DBG_LOOPANA, "Loop in edge from %+F (loop %d) to %+F (loop %d)\n", block, get_loop_loop_nr(loop),
 202                              cfgpred_block, get_loop_loop_nr(cfgpred_loop)));
 203
 204                         l = loop;
 205                         do {
 206                                 loop_attr_t *l_attr = get_loop_attr(env, l);
 207                                 set_insert(l_attr->in_edges, &edge, sizeof(edge), hash);
 208
 209                                 l = get_loop_outer_loop(l);
 210                         } while(l != cfgpred_loop);
 211                 }
 212         }
 213 }
 214
 215 static void free_loop_edges(morgan_env_t *env) {
 216         loop_attr_t *l_attr;
 217
 218         for(l_attr = set_first(env->loop_attr_set); l_attr != NULL; l_attr = set_next(env->loop_attr_set)) {
 219                 del_set(l_attr->out_edges);
 220                 del_set(l_attr->in_edges);
 221         }
 222 }
 223
 224 #if 0
 225 /**
 226  * Debugging help, shows all nodes in a (node-)bitset
 227  */
 228 static void show_nodebitset(ir_graph* irg, const bitset_t* bitset) {
 229         int i;
 230
 231         bitset_foreach(bitset, i) {
 232                 ir_node* node = get_idx_irn(irg, i);
 233                 ir_fprintf(stderr, " %+F", node);
 234         }
 235         fprintf(stderr, "\n");
 236 }
 237 #endif
 238
 239 /**
 240  * Construct the livethrough unused set for a block
 241  */
 242 static bitset_t *construct_block_livethrough_unused(morgan_env_t* env, const ir_node* block) {
 243         block_attr_t *block_attr = get_block_attr(env, block);
 244         ir_node *node;
 245         int i;
 246
 247         DBG((dbg, DBG_LIVE, "Processing block %d\n", get_irn_node_nr(block)));
 248         // copy all live-outs into the livethrough_unused set
 249         be_lv_foreach(env->cenv->lv, block, be_lv_state_in | be_lv_state_out, i) {
 250                 ir_node *irn = be_lv_get_irn(env->cenv->lv, block, i);
 251                 int node_idx;
 252
 253                 if(!consider_for_spilling(env->arch, env->cls, irn))
 254                         continue;
 255
 256                 node_idx = get_irn_idx(irn);
 257                 bitset_set(block_attr->livethrough_unused, node_idx);
 258         }
 259
 260         /*
 261          * All values that are used within the block are not unused (and therefore not
 262          * livethrough_unused)
 263          */
 264         sched_foreach(block, node) {
 265                 int i, arity;
 266
 267                 for(i = 0, arity = get_irn_arity(node); i < arity; ++i) {
 268                         int idx = get_irn_idx(get_irn_n(node, i));
 269                         bitset_clear(block_attr->livethrough_unused, idx);
 270                 }
 271         }
 272
 273         return block_attr->livethrough_unused;
 274 }
 275
 276 /**
 277  * Construct the livethrough unused set for a loop (and all its subloops+blocks)
 278  */
 279 static bitset_t *construct_loop_livethrough_unused(morgan_env_t *env, const ir_loop *loop) {
 280         int i;
 281         loop_attr_t* loop_attr = get_loop_attr(env, loop);
 282
 283         DBG((dbg, DBG_LIVE, "Processing Loop %d\n", loop->loop_nr));
 284         assert(get_loop_n_elements(loop) > 0);
 285         for(i = 0; i < get_loop_n_elements(loop); ++i) {
 286                 loop_element elem = get_loop_element(loop, i);
 287                 switch (*elem.kind) {
 288                 case k_ir_node: {
 289                         bitset_t *livethrough_block_unused;
 290                         assert(is_Block(elem.node));
 291                         livethrough_block_unused = construct_block_livethrough_unused(env, elem.node);
 292                         if(i == 0) {
 293                                 bitset_copy(loop_attr->livethrough_unused, livethrough_block_unused);
 294                         } else {
 295                                 bitset_and(loop_attr->livethrough_unused, livethrough_block_unused);
 296                         }
 297                         break;
 298                 }
 299                 case k_ir_loop: {
 300                         bitset_t *livethrough_son_unused;
 301
 302                         livethrough_son_unused = construct_loop_livethrough_unused(env, elem.son);
 303                         if(i == 0) {
 304                                 bitset_copy(loop_attr->livethrough_unused, livethrough_son_unused);
 305                         } else {
 306                                 bitset_and(loop_attr->livethrough_unused, livethrough_son_unused);
 307                         }
 308                         break;
 309                 }
 310             default:
 311                         assert(0);
 312                         break;
 313                 }
 314     }
 315         DBG((dbg, DBG_LIVE, "Done with loop %d\n", loop->loop_nr));
 316
 317         // remove all unused livethroughs that are remembered for this loop from child loops and blocks
 318         for(i = 0; i < get_loop_n_elements(loop); ++i) {
 319                 const loop_element elem = get_loop_element(loop, i);
 320
 321                 if(*elem.kind == k_ir_loop) {
 322                         loop_attr_t *son_attr = get_loop_attr(env, elem.son);
 323                         bitset_andnot(son_attr->livethrough_unused, loop_attr->livethrough_unused);
 324
 325                         DBG((dbg, DBG_LIVE, "Livethroughs for loop %d:\n", loop->loop_nr));
 326                 } else if(*elem.kind == k_ir_node) {
 327                         block_attr_t *block_attr = get_block_attr(env, elem.node);
 328                         bitset_andnot(block_attr->livethrough_unused, loop_attr->livethrough_unused);
 329
 330                         DBG((dbg, DBG_LIVE, "Livethroughs for block %+F\n", elem.node));
 331                 } else {
 332                         assert(0);
 333                 }
 334         }
 335
 336         return loop_attr->livethrough_unused;
 337 }
 338
 339 /*---------------------------------------------------------------------------*/
 340
 341 static int reduce_register_pressure_in_block(morgan_env_t *env, const ir_node* block, int loop_unused_spills_possible) {
 342         ir_node *node;
 343         int max_pressure;
 344         int loop_unused_spills_needed;
 345         pset *live_nodes = pset_new_ptr_default();
 346
 347         be_liveness_end_of_block(env->cenv->lv, env->arch, env->cls, block, live_nodes);
 348         max_pressure = pset_count(live_nodes);
 349
 350         DBG((dbg, DBG_LIVE, "Reduce pressure to %d In Block %+F:\n", env->registers_available, block));
 351
 352         /**
 353          * Determine register pressure in block
 354          */
 355         sched_foreach_reverse(block, node) {
 356                 int pressure;
 357
 358                 if(is_Phi(node))
 359                         break;
 360
 361                 be_liveness_transfer(env->arch, env->cls, node, live_nodes);
 362                 pressure = pset_count(live_nodes);
 363                 if(pressure > max_pressure)
 364                         max_pressure = pressure;
 365         }
 366         del_pset(live_nodes);
 367
 368         DBG((dbg, DBG_PRESSURE, "\tMax Pressure in %+F: %d\n", block, max_pressure));
 369
 370         loop_unused_spills_needed = max_pressure - env->registers_available;
 371
 372         if(loop_unused_spills_needed < 0) {
 373                 loop_unused_spills_needed = 0;
 374         } else if(loop_unused_spills_needed > loop_unused_spills_possible) {
 375                 loop_unused_spills_needed = loop_unused_spills_possible;
 376         }
 377
 378         DBG((dbg, DBG_PRESSURE, "Unused spills for Block %+F needed: %d\n", block, loop_unused_spills_needed));
 379         return loop_unused_spills_needed;
 380 }
 381
 382 /**
 383  * Reduce register pressure in a loop
 384  *
 385  * @param unused_spills_possible        Number of spills from livethrough_unused variables possible in outer loops
 386  * @return                                                      Number of spills of livethrough_unused variables needed in outer loops
 387  */
 388 static int reduce_register_pressure_in_loop(morgan_env_t *env, const ir_loop *loop, int outer_spills_possible) {
 389         int i;
 390         loop_attr_t* loop_attr = get_loop_attr(env, loop);
 391         int spills_needed = 0;
 392         int spills_possible = outer_spills_possible + bitset_popcnt(loop_attr->livethrough_unused);
 393         int outer_spills_needed;
 394
 395         DBG((dbg, DBG_PRESSURE, "Reducing Pressure in loop %d\n", loop->loop_nr));
 396         for(i = 0; i < get_loop_n_elements(loop); ++i) {
 397                 loop_element elem = get_loop_element(loop, i);
 398                 switch (*elem.kind) {
 399                 case k_ir_node: {
 400                         int needed;
 401                         assert(is_Block(elem.node));
 402                         needed = reduce_register_pressure_in_block(env, elem.node, spills_possible);
 403                         assert(needed >= 0);
 404                         assert(needed <= spills_possible);
 405                         if(needed > spills_needed)
 406                                 spills_needed = needed;
 407                         break;
 408                 }
 409                 case k_ir_loop: {
 410                         int needed = reduce_register_pressure_in_loop(env, elem.son, spills_possible);
 411                         assert(needed >= 0);
 412                         assert(needed <= spills_possible);
 413                         if(needed > spills_needed)
 414                                 spills_needed = needed;
 415                         break;
 416                 }
 417             default:
 418                         assert(0);
 419                         break;
 420                 }
 421     }
 422
 423         /* calculate number of spills needed in outer loop and spill
 424          * unused livethrough nodes around this loop
 425          */
 426         if(spills_needed > outer_spills_possible) {
 427                 int spills_to_place;
 428                 outer_spills_needed = outer_spills_possible;
 429                 spills_needed -= outer_spills_possible;
 430
 431                 spills_to_place = spills_needed;
 432
 433                 DBG((dbg, DBG_SPILLS, "%d values unused in loop %d, spilling %d\n",
 434                  spills_possible - outer_spills_possible, loop->loop_nr, spills_to_place));
 435
 436                 bitset_foreach(loop_attr->livethrough_unused, i) {
 437                         loop_edge_t *edge;
 438                         ir_node *to_spill = get_idx_irn(env->irg, i);
 439
 440                         DBG((dbg, DBG_SPILLS, "Spilling node %+F around loop %d\n", to_spill, loop->loop_nr));
 441
 442                         for(edge = set_first(loop_attr->out_edges); edge != NULL; edge = set_next(loop_attr->out_edges)) {
 443                                 be_add_reload_on_edge(env->senv, to_spill, edge->block, edge->pos);
 444                         }
 445
 446                         spills_to_place--;
 447                         if(spills_to_place <= 0) {
 448                                 break;
 449                         }
 450                 }
 451         } else {
 452                 outer_spills_needed = spills_needed;
 453         }
 454
 455         return outer_spills_needed;
 456 }
 457
 458 void be_spill_morgan(be_chordal_env_t *chordal_env) {
 459         morgan_env_t env;
 460
 461         FIRM_DBG_REGISTER(dbg, "ir.be.spillmorgan");
 462         //firm_dbg_set_mask(dbg, DBG_SPILLS | DBG_LOOPANA);
 463
 464         env.cenv = chordal_env;
 465         env.arch = chordal_env->birg->main_env->arch_env;
 466         env.irg = chordal_env->irg;
 467         env.cls = chordal_env->cls;
 468         env.senv = be_new_spill_env(chordal_env);
 469         DEBUG_ONLY(be_set_spill_env_dbg_module(env.senv, dbg);)
 470
 471         obstack_init(&env.obst);
 472
 473         env.registers_available = env.cls->n_regs - be_put_ignore_regs(chordal_env->birg, env.cls, NULL);
 474
 475         env.loop_attr_set = new_set(loop_attr_cmp, 5);
 476         env.block_attr_set = new_set(block_attr_cmp, 20);
 477
 478         /*-- Part1: Analysis --*/
 479         be_liveness_recompute(chordal_env->lv);
 480
 481         /* construct control flow loop tree */
 482         construct_cf_backedges(chordal_env->irg);
 483
 484         /* construct loop out edges and livethrough_unused sets for loops and blocks */
 485         irg_block_walk_graph(chordal_env->irg, NULL, construct_loop_edges, &env);
 486         construct_loop_livethrough_unused(&env, get_irg_loop(env.irg));
 487
 488         /*-- Part2: Transformation --*/
 489
 490         /* spill unused livethrough values around loops and blocks where
 491          * the pressure is too high
 492          */
 493         reduce_register_pressure_in_loop(&env, get_irg_loop(env.irg), 0);
 494
 495         /* Insert real spill/reload nodes and fix usages */
 496         be_insert_spills_reloads(env.senv);
 497
 498         /* Verify the result */
 499         if (chordal_env->opts->vrfy_option == BE_CH_VRFY_WARN) {
 500                 be_verify_schedule(env.irg);
 501         } else if (chordal_env->opts->vrfy_option == BE_CH_VRFY_ASSERT) {
 502                 assert(be_verify_schedule(env.irg));
 503         }
 504
 505         if (chordal_env->opts->dump_flags & BE_CH_DUMP_SPILL)
 506                 be_dump(env.irg, "-spillmorgan", dump_ir_block_graph_sched);
 507
 508         /* cleanup */
 509         free_loop_edges(&env);
 510         del_set(env.loop_attr_set);
 511         del_set(env.block_attr_set);
 512
 513         /* fix the remaining places with too high register pressure with beladies algorithm */
 514         be_spill_belady_spill_env(chordal_env, env.senv);
 515
 516         be_delete_spill_env(env.senv);
 517         obstack_free(&env.obst, NULL);
 518 }