mono/mini/liveness.c

   1 /*
   2  * liveness.c: liveness analysis
   3  *
   4  * Author:
   5  *   Dietmar Maurer (dietmar@ximian.com)
   6  *
   7  * (C) 2002 Ximian, Inc.
   8  */
   9
  10 #include "mini.h"
  11 #include "inssel.h"
  12 #include "aliasing.h"
  13
  14 #define SPILL_COST_INCREMENT (1 << (bb->nesting << 1))
  15
  16 //#define DEBUG_LIVENESS
  17
  18 #if SIZEOF_VOID_P == 8
  19 #define BITS_PER_CHUNK 64
  20 #else
  21 #define BITS_PER_CHUNK 32
  22 #endif
  23
  24 /*
  25  * The liveness2 pass can't handle long vars on 32 bit platforms because the component
  26  * vars have the same 'idx'.
  27  */
  28 #if SIZEOF_VOID_P == 8
  29 //#define ENABLE_LIVENESS2
  30 #endif
  31
  32 #ifdef ENABLE_LIVENESS2
  33 static void mono_analyze_liveness2 (MonoCompile *cfg);
  34 #endif
  35
  36 static void
  37 optimize_initlocals (MonoCompile *cfg);
  38
  39 static void
  40 optimize_initlocals2 (MonoCompile *cfg);
  41
  42 /* mono_bitset_mp_new:
  43  *
  44  * allocates a MonoBitSet inside a memory pool
  45  */
  46 static inline MonoBitSet*
  47 mono_bitset_mp_new (MonoMemPool *mp, guint32 size, guint32 max_size)
  48 {
  49         guint8 *mem = mono_mempool_alloc0 (mp, size);
  50         return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
  51 }
  52
  53 static inline MonoBitSet*
  54 mono_bitset_mp_new_noinit (MonoMemPool *mp, guint32 size, guint32 max_size)
  55 {
  56         guint8 *mem = mono_mempool_alloc (mp, size);
  57         return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
  58 }
  59
  60 G_GNUC_UNUSED static void
  61 mono_bitset_print (MonoBitSet *set)
  62 {
  63         int i;
  64
  65         printf ("{");
  66         for (i = 0; i < mono_bitset_size (set); i++) {
  67
  68                 if (mono_bitset_test (set, i))
  69                         printf ("%d, ", i);
  70
  71         }
  72         printf ("}\n");
  73 }
  74
  75 static inline void
  76 update_live_range (MonoCompile *cfg, int idx, int block_dfn, int tree_pos)
  77 {
  78         MonoLiveRange *range = &MONO_VARINFO (cfg, idx)->range;
  79         guint32 abs_pos = (block_dfn << 16) | tree_pos;
  80
  81         if (range->first_use.abs_pos > abs_pos)
  82                 range->first_use.abs_pos = abs_pos;
  83
  84         if (range->last_use.abs_pos < abs_pos)
  85                 range->last_use.abs_pos = abs_pos;
  86 }
  87
  88 static void
  89 update_gen_kill_set (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst, int inst_num)
  90 {
  91         int arity;
  92         int max_vars = cfg->num_varinfo;
  93
  94         arity = mono_burg_arity [inst->opcode];
  95         if (arity)
  96                 update_gen_kill_set (cfg, bb, inst->inst_i0, inst_num);
  97
  98         if (arity > 1)
  99                 update_gen_kill_set (cfg, bb, inst->inst_i1, inst_num);
 100
 101         if ((inst->ssa_op & MONO_SSA_LOAD_STORE) || (inst->opcode == OP_DUMMY_STORE)) {
 102                 MonoLocalVariableList* affected_variables;
 103                 MonoLocalVariableList local_affected_variable;
 104
 105                 if (cfg->aliasing_info == NULL) {
 106                         if ((inst->ssa_op == MONO_SSA_LOAD) || (inst->ssa_op == MONO_SSA_STORE) || (inst->opcode == OP_DUMMY_STORE)) {
 107                                 local_affected_variable.variable_index = inst->inst_i0->inst_c0;
 108                                 local_affected_variable.next = NULL;
 109                                 affected_variables = &local_affected_variable;
 110                         } else {
 111                                 affected_variables = NULL;
 112                         }
 113                 } else {
 114                         affected_variables = mono_aliasing_get_affected_variables_for_inst_traversing_code (cfg->aliasing_info, inst);
 115                 }
 116
 117                 if (inst->ssa_op & MONO_SSA_LOAD) {
 118                         MonoLocalVariableList* affected_variable = affected_variables;
 119                         while (affected_variable != NULL) {
 120                                 int idx = affected_variable->variable_index;
 121                                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 122                                 g_assert (idx < max_vars);
 123                                 update_live_range (cfg, idx, bb->dfn, inst_num);
 124                                 if (!mono_bitset_test_fast (bb->kill_set, idx))
 125                                         mono_bitset_set_fast (bb->gen_set, idx);
 126                                 if (inst->ssa_op == MONO_SSA_LOAD)
 127                                         vi->spill_costs += SPILL_COST_INCREMENT;
 128
 129                                 affected_variable = affected_variable->next;
 130                         }
 131                 } else if ((inst->ssa_op == MONO_SSA_STORE) || (inst->opcode == OP_DUMMY_STORE)) {
 132                         MonoLocalVariableList* affected_variable = affected_variables;
 133                         while (affected_variable != NULL) {
 134                                 int idx = affected_variable->variable_index;
 135                                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 136                                 g_assert (idx < max_vars);
 137                                 //if (arity > 0)
 138                                         //g_assert (inst->inst_i1->opcode != OP_PHI);
 139                                 update_live_range (cfg, idx, bb->dfn, inst_num);
 140                                 mono_bitset_set_fast (bb->kill_set, idx);
 141                                 if (inst->ssa_op == MONO_SSA_STORE)
 142                                         vi->spill_costs += SPILL_COST_INCREMENT;
 143
 144                                 affected_variable = affected_variable->next;
 145                         }
 146                 }
 147         } else if (inst->opcode == OP_JMP) {
 148                 /* Keep arguments live! */
 149                 int i;
 150                 for (i = 0; i < cfg->num_varinfo; i++) {
 151                         if (cfg->varinfo [i]->opcode == OP_ARG) {
 152                                 if (!mono_bitset_test_fast (bb->kill_set, i))
 153                                         mono_bitset_set_fast (bb->gen_set, i);
 154                         }
 155                 }
 156         }
 157 }
 158
 159 static void
 160 update_volatile (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *inst)
 161 {
 162         int arity = mono_burg_arity [inst->opcode];
 163         int max_vars = cfg->num_varinfo;
 164
 165         if (arity)
 166                 update_volatile (cfg, bb, inst->inst_i0);
 167
 168         if (arity > 1)
 169                 update_volatile (cfg, bb, inst->inst_i1);
 170
 171         if (inst->ssa_op & MONO_SSA_LOAD_STORE) {
 172                 MonoLocalVariableList* affected_variables;
 173                 MonoLocalVariableList local_affected_variable;
 174
 175                 if (cfg->aliasing_info == NULL) {
 176                         if ((inst->ssa_op == MONO_SSA_LOAD) || (inst->ssa_op == MONO_SSA_STORE)) {
 177                                 local_affected_variable.variable_index = inst->inst_i0->inst_c0;
 178                                 local_affected_variable.next = NULL;
 179                                 affected_variables = &local_affected_variable;
 180                         } else {
 181                                 affected_variables = NULL;
 182                         }
 183                 } else {
 184                         affected_variables = mono_aliasing_get_affected_variables_for_inst_traversing_code (cfg->aliasing_info, inst);
 185                 }
 186
 187                 while (affected_variables != NULL) {
 188                         int idx = affected_variables->variable_index;
 189                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 190                         g_assert (idx < max_vars);
 191                         cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
 192
 193                         affected_variables = affected_variables->next;
 194                 }
 195         }
 196 }
 197
 198 static void
 199 visit_bb (MonoCompile *cfg, MonoBasicBlock *bb, GSList **visited)
 200 {
 201         int i;
 202         MonoInst *ins;
 203
 204         if (g_slist_find (*visited, bb))
 205                 return;
 206
 207         if (cfg->new_ir) {
 208                 for (ins = bb->code; ins; ins = ins->next) {
 209                         const char *spec = INS_INFO (ins->opcode);
 210                         int regtype, srcindex, sreg;
 211
 212                         if (ins->opcode == OP_NOP)
 213                                 continue;
 214
 215                         /* DREG */
 216                         regtype = spec [MONO_INST_DEST];
 217                         g_assert (((ins->dreg == -1) && (regtype == ' ')) || ((ins->dreg != -1) && (regtype != ' ')));
 218
 219                         if ((ins->dreg != -1) && get_vreg_to_inst (cfg, ins->dreg)) {
 220                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 221                                 int idx = var->inst_c0;
 222                                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 223
 224                                 cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
 225                         }
 226
 227                         /* SREGS */
 228                         for (srcindex = 0; srcindex < 2; ++srcindex) {
 229                                 regtype = spec [(srcindex == 0) ? MONO_INST_SRC1 : MONO_INST_SRC2];
 230                                 sreg = srcindex == 0 ? ins->sreg1 : ins->sreg2;
 231
 232                                 g_assert (((sreg == -1) && (regtype == ' ')) || ((sreg != -1) && (regtype != ' ')));
 233                                 if ((sreg != -1) && get_vreg_to_inst (cfg, sreg)) {
 234                                         MonoInst *var = get_vreg_to_inst (cfg, sreg);
 235                                         int idx = var->inst_c0;
 236                                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 237
 238                                         cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
 239                                 }
 240                         }
 241                 }
 242         } else {
 243                 if (cfg->aliasing_info != NULL)
 244                         mono_aliasing_initialize_code_traversal (cfg->aliasing_info, bb);
 245
 246                 for (ins = bb->code; ins; ins = ins->next) {
 247                         update_volatile (cfg, bb, ins);
 248                 }
 249         }
 250
 251         *visited = g_slist_append (*visited, bb);
 252
 253         /*
 254          * Need to visit all bblocks reachable from this one since they can be
 255          * reached during exception handling.
 256          */
 257         for (i = 0; i < bb->out_count; ++i) {
 258                 visit_bb (cfg, bb->out_bb [i], visited);
 259         }
 260 }
 261
 262 void
 263 mono_liveness_handle_exception_clauses (MonoCompile *cfg)
 264 {
 265         MonoBasicBlock *bb;
 266         GSList *visited = NULL;
 267
 268         /*
 269          * Variables in exception handler register cannot be allocated to registers
 270          * so make them volatile. See bug #42136. This will not be neccessary when
 271          * the back ends could guarantee that the variables will be in the
 272          * correct registers when a handler is called.
 273          * This includes try blocks too, since a variable in a try block might be
 274          * accessed after an exception handler has been run.
 275          */
 276         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 277
 278                 if (bb->region == -1 || MONO_BBLOCK_IS_IN_REGION (bb, MONO_REGION_TRY))
 279                         continue;
 280
 281                 visit_bb (cfg, bb, &visited);
 282         }
 283         g_slist_free (visited);
 284 }
 285
 286 static inline void
 287 update_live_range2 (MonoMethodVar *var, int abs_pos)
 288 {
 289         if (var->range.first_use.abs_pos > abs_pos)
 290                 var->range.first_use.abs_pos = abs_pos;
 291
 292         if (var->range.last_use.abs_pos < abs_pos)
 293                 var->range.last_use.abs_pos = abs_pos;
 294 }
 295
 296 static void
 297 analyze_liveness_bb (MonoCompile *cfg, MonoBasicBlock *bb)
 298 {
 299         MonoInst *ins;
 300         int sreg, inst_num;
 301         MonoMethodVar *vars = cfg->vars;
 302         guint32 abs_pos = (bb->dfn << 16);
 303
 304         for (inst_num = 0, ins = bb->code; ins; ins = ins->next, inst_num += 2) {
 305                 const char *spec = INS_INFO (ins->opcode);
 306
 307 #ifdef DEBUG_LIVENESS
 308                         printf ("\t"); mono_print_ins (ins);
 309 #endif
 310
 311                 if (ins->opcode == OP_NOP)
 312                         continue;
 313
 314                 if (ins->opcode == OP_LDADDR) {
 315                         MonoInst *var = ins->inst_p0;
 316                         int idx = var->inst_c0;
 317                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 318
 319 #ifdef DEBUG_LIVENESS
 320                         printf ("\tGEN: R%d(%d)\n", var->dreg, idx);
 321 #endif
 322                         update_live_range2 (&vars [idx], abs_pos + inst_num);
 323                         if (!mono_bitset_test_fast (bb->kill_set, idx))
 324                                 mono_bitset_set_fast (bb->gen_set, idx);
 325                         vi->spill_costs += SPILL_COST_INCREMENT;
 326                 }
 327
 328                 /* SREGs must come first, so MOVE r <- r is handled correctly */
 329
 330                 /* SREG1 */
 331                 sreg = ins->sreg1;
 332                 if ((spec [MONO_INST_SRC1] != ' ') && get_vreg_to_inst (cfg, sreg)) {
 333                         MonoInst *var = get_vreg_to_inst (cfg, sreg);
 334                         int idx = var->inst_c0;
 335                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 336
 337 #ifdef DEBUG_LIVENESS
 338                         printf ("\tGEN: R%d(%d)\n", sreg, idx);
 339 #endif
 340                         update_live_range2 (&vars [idx], abs_pos + inst_num);
 341                         if (!mono_bitset_test_fast (bb->kill_set, idx))
 342                                 mono_bitset_set_fast (bb->gen_set, idx);
 343                         vi->spill_costs += SPILL_COST_INCREMENT;
 344                 }
 345
 346                 /* SREG2 */
 347                 sreg = ins->sreg2;
 348                 if ((spec [MONO_INST_SRC2] != ' ') && get_vreg_to_inst (cfg, sreg)) {
 349                         MonoInst *var = get_vreg_to_inst (cfg, sreg);
 350                         int idx = var->inst_c0;
 351                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 352
 353 #ifdef DEBUG_LIVENESS
 354                         printf ("\tGEN: R%d(%d)\n", sreg, idx);
 355 #endif
 356                         update_live_range2 (&vars [idx], abs_pos + inst_num);
 357                         if (!mono_bitset_test_fast (bb->kill_set, idx))
 358                                 mono_bitset_set_fast (bb->gen_set, idx);
 359                         vi->spill_costs += SPILL_COST_INCREMENT;
 360                 }
 361
 362                 /* DREG */
 363                 if ((spec [MONO_INST_DEST] != ' ') && get_vreg_to_inst (cfg, ins->dreg)) {
 364                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 365                         int idx = var->inst_c0;
 366                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 367
 368                         if (MONO_IS_STORE_MEMBASE (ins)) {
 369                                 update_live_range2 (&vars [idx], abs_pos + inst_num);
 370                                 if (!mono_bitset_test_fast (bb->kill_set, idx))
 371                                         mono_bitset_set_fast (bb->gen_set, idx);
 372                                 vi->spill_costs += SPILL_COST_INCREMENT;
 373                         } else {
 374 #ifdef DEBUG_LIVENESS
 375                                 printf ("\tKILL: R%d(%d)\n", ins->dreg, idx);
 376 #endif
 377                                 update_live_range2 (&vars [idx], abs_pos + inst_num + 1);
 378                                 mono_bitset_set_fast (bb->kill_set, idx);
 379                                 vi->spill_costs += SPILL_COST_INCREMENT;
 380                         }
 381                 }
 382         }
 383 }
 384
 385 /* generic liveness analysis code. CFG specific parts are
 386  * in update_gen_kill_set()
 387  */
 388 void
 389 mono_analyze_liveness (MonoCompile *cfg)
 390 {
 391         MonoBitSet *old_live_out_set;
 392         int i, j, max_vars = cfg->num_varinfo;
 393         int out_iter;
 394         gboolean *in_worklist;
 395         MonoBasicBlock **worklist;
 396         guint32 l_end;
 397         int bitsize;
 398
 399 #ifdef DEBUG_LIVENESS
 400         printf ("LIVENESS %s\n", mono_method_full_name (cfg->method, TRUE));
 401 #endif
 402
 403         g_assert (!(cfg->comp_done & MONO_COMP_LIVENESS));
 404
 405         cfg->comp_done |= MONO_COMP_LIVENESS;
 406
 407         if (max_vars == 0)
 408                 return;
 409
 410         bitsize = mono_bitset_alloc_size (max_vars, 0);
 411
 412         for (i = 0; i < max_vars; i ++) {
 413                 MONO_VARINFO (cfg, i)->range.first_use.abs_pos = ~ 0;
 414                 MONO_VARINFO (cfg, i)->range.last_use .abs_pos =   0;
 415                 MONO_VARINFO (cfg, i)->spill_costs = 0;
 416         }
 417
 418         for (i = 0; i < cfg->num_bblocks; ++i) {
 419                 MonoBasicBlock *bb = cfg->bblocks [i];
 420                 MonoInst *inst;
 421                 int tree_num;
 422
 423                 bb->gen_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 424                 bb->kill_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 425
 426                 if (cfg->new_ir) {
 427                         analyze_liveness_bb (cfg, bb);
 428                 } else {
 429                         if (cfg->aliasing_info != NULL)
 430                                 mono_aliasing_initialize_code_traversal (cfg->aliasing_info, bb);
 431
 432                         tree_num = 0;
 433                         MONO_BB_FOR_EACH_INS (bb, inst) {
 434 #ifdef DEBUG_LIVENESS
 435                                 mono_print_tree (inst); printf ("\n");
 436 #endif
 437                                 update_gen_kill_set (cfg, bb, inst, tree_num);
 438                                 tree_num ++;
 439                         }
 440                 }
 441
 442 #ifdef DEBUG_LIVENESS
 443                 printf ("BLOCK BB%d (", bb->block_num);
 444                 for (j = 0; j < bb->out_count; j++)
 445                         printf ("BB%d, ", bb->out_bb [j]->block_num);
 446
 447                 printf (")\n");
 448                 printf ("GEN  BB%d: ", bb->block_num); mono_bitset_print (bb->gen_set);
 449                 printf ("KILL BB%d: ", bb->block_num); mono_bitset_print (bb->kill_set);
 450 #endif
 451         }
 452
 453         old_live_out_set = mono_bitset_new (max_vars, 0);
 454         in_worklist = g_new0 (gboolean, cfg->num_bblocks + 1);
 455
 456         worklist = g_new (MonoBasicBlock *, cfg->num_bblocks + 1);
 457         l_end = 0;
 458
 459         /*
 460          * This is a backward dataflow analysis problem, so we process blocks in
 461          * decreasing dfn order, this speeds up the iteration.
 462          */
 463         for (i = 0; i < cfg->num_bblocks; i ++) {
 464                 MonoBasicBlock *bb = cfg->bblocks [i];
 465
 466                 worklist [l_end ++] = bb;
 467                 in_worklist [bb->dfn] = TRUE;
 468
 469                 /* Initialized later */
 470                 bb->live_in_set = NULL;
 471                 bb->live_out_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 472         }
 473
 474         out_iter = 0;
 475
 476         while (l_end != 0) {
 477                 MonoBasicBlock *bb = worklist [--l_end];
 478                 MonoBasicBlock *out_bb;
 479                 gboolean changed;
 480
 481                 in_worklist [bb->dfn] = FALSE;
 482
 483 #ifdef DEBUG_LIVENESS
 484                 printf ("P: %d(%d): IN: ", bb->block_num, bb->dfn);
 485                 for (j = 0; j < bb->in_count; ++j)
 486                         printf ("BB%d ", bb->in_bb [j]->block_num);
 487                 printf ("OUT:");
 488                 for (j = 0; j < bb->out_count; ++j)
 489                         printf ("BB%d ", bb->out_bb [j]->block_num);
 490                 printf ("\n");
 491 #endif
 492
 493
 494                 if (bb->out_count == 0)
 495                         continue;
 496
 497                 out_iter ++;
 498
 499                 if (!bb->live_in_set) {
 500                         /* First pass over this bblock */
 501                         changed = TRUE;
 502                 }
 503                 else {
 504                         changed = FALSE;
 505                         mono_bitset_copyto_fast (bb->live_out_set, old_live_out_set);
 506                 }
 507
 508                 for (j = 0; j < bb->out_count; j++) {
 509                         out_bb = bb->out_bb [j];
 510
 511                         if (!out_bb->live_in_set) {
 512                                 out_bb->live_in_set = mono_bitset_mp_new_noinit (cfg->mempool, bitsize, max_vars);
 513
 514                                 mono_bitset_copyto_fast (out_bb->live_out_set, out_bb->live_in_set);
 515                                 mono_bitset_sub_fast (out_bb->live_in_set, out_bb->kill_set);
 516                                 mono_bitset_union_fast (out_bb->live_in_set, out_bb->gen_set);
 517                         }
 518
 519                         mono_bitset_union_fast (bb->live_out_set, out_bb->live_in_set);
 520                 }
 521
 522                 if (changed || !mono_bitset_equal (old_live_out_set, bb->live_out_set)) {
 523                         if (!bb->live_in_set)
 524                                 bb->live_in_set = mono_bitset_mp_new_noinit (cfg->mempool, bitsize, max_vars);
 525                         mono_bitset_copyto_fast (bb->live_out_set, bb->live_in_set);
 526                         mono_bitset_sub_fast (bb->live_in_set, bb->kill_set);
 527                         mono_bitset_union_fast (bb->live_in_set, bb->gen_set);
 528
 529                         for (j = 0; j < bb->in_count; j++) {
 530                                 MonoBasicBlock *in_bb = bb->in_bb [j];
 531                                 /*
 532                                  * Some basic blocks do not seem to be in the
 533                                  * cfg->bblocks array...
 534                                  */
 535                                 if (in_bb->gen_set && !in_worklist [in_bb->dfn]) {
 536 #ifdef DEBUG_LIVENESS
 537                                         printf ("\tADD: %d\n", in_bb->block_num);
 538 #endif
 539                                         /*
 540                                          * Put the block at the top of the stack, so it
 541                                          * will be processed right away.
 542                                          */
 543                                         worklist [l_end ++] = in_bb;
 544                                         in_worklist [in_bb->dfn] = TRUE;
 545                                 }
 546                         }
 547                 }
 548         }
 549
 550 #ifdef DEBUG_LIVENESS
 551                 printf ("IT: %d %d.\n", cfg->num_bblocks, out_iter);
 552 #endif
 553
 554         mono_bitset_free (old_live_out_set);
 555
 556         g_free (worklist);
 557         g_free (in_worklist);
 558
 559         /* Compute live_in_set for bblocks skipped earlier */
 560         for (i = 0; i < cfg->num_bblocks; ++i) {
 561                 MonoBasicBlock *bb = cfg->bblocks [i];
 562
 563                 if (!bb->live_in_set) {
 564                         bb->live_in_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 565
 566                         mono_bitset_copyto_fast (bb->live_out_set, bb->live_in_set);
 567                         mono_bitset_sub_fast (bb->live_in_set, bb->kill_set);
 568                         mono_bitset_union_fast (bb->live_in_set, bb->gen_set);
 569                 }
 570         }
 571
 572         for (i = 0; i < cfg->num_bblocks; ++i) {
 573                 MonoBasicBlock *bb = cfg->bblocks [i];
 574                 guint32 rem, max;
 575                 guint32 abs_pos = (bb->dfn << 16);
 576                 MonoMethodVar *vars = cfg->vars;
 577
 578                 if (!bb->live_out_set)
 579                         continue;
 580
 581                 rem = max_vars % BITS_PER_CHUNK;
 582                 max = ((max_vars + (BITS_PER_CHUNK -1)) / BITS_PER_CHUNK);
 583                 for (j = 0; j < max; ++j) {
 584                         gsize bits_in;
 585                         gsize bits_out;
 586                         int k;
 587
 588                         bits_in = mono_bitset_get_fast (bb->live_in_set, j);
 589                         bits_out = mono_bitset_get_fast (bb->live_out_set, j);
 590
 591                         k = (j * BITS_PER_CHUNK);
 592                         while ((bits_in || bits_out)) {
 593                                 if (bits_in & 1)
 594                                         update_live_range2 (&vars [k], abs_pos + 0);
 595                                 if (bits_out & 1)
 596                                         update_live_range2 (&vars [k], abs_pos + 0xffff);
 597                                 bits_in >>= 1;
 598                                 bits_out >>= 1;
 599                                 k ++;
 600                         }
 601                 }
 602         }
 603
 604         /*
 605          * Arguments need to have their live ranges extended to the beginning of
 606          * the method to account for the arg reg/memory -> global register copies
 607          * in the prolog (bug #74992).
 608          */
 609
 610         for (i = 0; i < max_vars; i ++) {
 611                 MonoMethodVar *vi = MONO_VARINFO (cfg, i);
 612                 if (cfg->varinfo [vi->idx]->opcode == OP_ARG) {
 613                         if (vi->range.last_use.abs_pos == 0 && !(cfg->varinfo [vi->idx]->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 614                                 /*
 615                                  * Can't eliminate the this variable in gshared code, since
 616                                  * it is needed during exception handling to identify the
 617                                  * method.
 618                                  * It is better to check for this here instead of marking the variable
 619                                  * VOLATILE, since that would prevent it from being allocated to
 620                                  * registers.
 621                                  */
 622                                  if (!(cfg->generic_sharing_context && mono_method_signature (cfg->method)->hasthis && cfg->varinfo [vi->idx] == cfg->args [0]))
 623                                          cfg->varinfo [vi->idx]->flags |= MONO_INST_IS_DEAD;
 624                         }
 625                         vi->range.first_use.abs_pos = 0;
 626                 }
 627         }
 628
 629 #ifdef DEBUG_LIVENESS
 630         for (i = cfg->num_bblocks - 1; i >= 0; i--) {
 631                 MonoBasicBlock *bb = cfg->bblocks [i];
 632
 633                 printf ("LIVE IN  BB%d: ", bb->block_num);
 634                 mono_bitset_print (bb->live_in_set);
 635                 printf ("LIVE OUT BB%d: ", bb->block_num);
 636                 mono_bitset_print (bb->live_out_set);
 637         }
 638 #endif
 639
 640         if (cfg->new_ir) {
 641                 if (!cfg->disable_initlocals_opt)
 642                         optimize_initlocals2 (cfg);
 643
 644 #ifdef ENABLE_LIVENESS2
 645                 /* This improves code size by about 5% but slows down compilation too much */
 646                 /* FIXME: This crashes when compiling 2.0 mscorlib */
 647                 if (FALSE && cfg->compile_aot)
 648                         mono_analyze_liveness2 (cfg);
 649 #endif
 650         }
 651         else {
 652                 if (!cfg->disable_initlocals_opt)
 653                         optimize_initlocals (cfg);
 654         }
 655 }
 656
 657 /**
 658  * optimize_initlocals:
 659  *
 660  * Try to optimize away some of the redundant initialization code inserted because of
 661  * 'locals init' using the liveness information.
 662  */
 663 static void
 664 optimize_initlocals2 (MonoCompile *cfg)
 665 {
 666         MonoBitSet *used;
 667         MonoInst *ins;
 668         MonoBasicBlock *initlocals_bb;
 669
 670         used = mono_bitset_new (cfg->next_vreg + 1, 0);
 671
 672         mono_bitset_clear_all (used);
 673         initlocals_bb = cfg->bb_entry->next_bb;
 674         for (ins = initlocals_bb->code; ins; ins = ins->next) {
 675                 const char *spec = INS_INFO (ins->opcode);
 676
 677                 if (spec [MONO_INST_SRC1] != ' ')
 678                         mono_bitset_set_fast (used, ins->sreg1);
 679                 if (spec [MONO_INST_SRC2] != ' ')
 680                         mono_bitset_set_fast (used, ins->sreg2);
 681                 if (MONO_IS_STORE_MEMBASE (ins))
 682                         mono_bitset_set_fast (used, ins->dreg);
 683         }
 684
 685         for (ins = initlocals_bb->code; ins; ins = ins->next) {
 686                 const char *spec = INS_INFO (ins->opcode);
 687
 688                 /* Look for statements whose dest is not used in this bblock and not live on exit. */
 689                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 690                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 691
 692                         if (var && !mono_bitset_test_fast (used, ins->dreg) && !mono_bitset_test_fast (initlocals_bb->live_out_set, var->inst_c0) && (var != cfg->ret) && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 693                                 //printf ("DEAD: "); mono_print_ins (ins);
 694                                 if ((ins->opcode == OP_ICONST) || (ins->opcode == OP_I8CONST) || (ins->opcode == OP_R8CONST)) {
 695                                         NULLIFY_INS (ins);
 696                                         MONO_VARINFO (cfg, var->inst_c0)->spill_costs -= 1;
 697                                         /*
 698                                          * We should shorten the liveness interval of these vars as well, but
 699                                          * don't have enough info to do that.
 700                                          */
 701                                 }
 702                         }
 703                 }
 704         }
 705
 706         g_free (used);
 707 }
 708
 709 void
 710 mono_linterval_add_range (MonoCompile *cfg, MonoLiveInterval *interval, int from, int to)
 711 {
 712         MonoLiveRange2 *prev_range, *next_range, *new_range;
 713
 714         g_assert (to >= from);
 715
 716         /* Optimize for extending the first interval backwards */
 717         if (G_LIKELY (interval->range && (interval->range->from > from) && (interval->range->from == to))) {
 718                 interval->range->from = from;
 719                 return;
 720         }
 721
 722         /* Find a place in the list for the new range */
 723         prev_range = NULL;
 724         next_range = interval->range;
 725         while ((next_range != NULL) && (next_range->from <= from)) {
 726                 prev_range = next_range;
 727                 next_range = next_range->next;
 728         }
 729
 730         if (prev_range && prev_range->to == from) {
 731                 /* Merge with previous */
 732                 prev_range->to = to;
 733         } else if (next_range && next_range->from == to) {
 734                 /* Merge with previous */
 735                 next_range->from = from;
 736         } else {
 737                 /* Insert it */
 738                 new_range = mono_mempool_alloc (cfg->mempool, sizeof (MonoLiveRange2));
 739                 new_range->from = from;
 740                 new_range->to = to;
 741                 new_range->next = NULL;
 742
 743                 if (prev_range)
 744                         prev_range->next = new_range;
 745                 else
 746                         interval->range = new_range;
 747                 if (next_range)
 748                         new_range->next = next_range;
 749                 else
 750                         interval->last_range = new_range;
 751         }
 752
 753         /* FIXME: Merge intersecting ranges */
 754 }
 755
 756 void
 757 mono_linterval_print (MonoLiveInterval *interval)
 758 {
 759         MonoLiveRange2 *range;
 760
 761         for (range = interval->range; range != NULL; range = range->next)
 762                 printf ("[%x-%x] ", range->from, range->to);
 763 }
 764
 765 void
 766 mono_linterval_print_nl (MonoLiveInterval *interval)
 767 {
 768         mono_linterval_print (interval);
 769         printf ("\n");
 770 }
 771
 772 /**
 773  * mono_linterval_convers:
 774  *
 775  *   Return whenever INTERVAL covers the position POS.
 776  */
 777 gboolean
 778 mono_linterval_covers (MonoLiveInterval *interval, int pos)
 779 {
 780         MonoLiveRange2 *range;
 781
 782         for (range = interval->range; range != NULL; range = range->next) {
 783                 if (pos >= range->from && pos <= range->to)
 784                         return TRUE;
 785                 if (range->from > pos)
 786                         return FALSE;
 787         }
 788
 789         return FALSE;
 790 }
 791
 792 /**
 793  * mono_linterval_get_intersect_pos:
 794  *
 795  *   Determine whenever I1 and I2 intersect, and if they do, return the first
 796  * point of intersection. Otherwise, return -1.
 797  */
 798 gint32
 799 mono_linterval_get_intersect_pos (MonoLiveInterval *i1, MonoLiveInterval *i2)
 800 {
 801         MonoLiveRange2 *r1, *r2;
 802
 803         /* FIXME: Optimize this */
 804         for (r1 = i1->range; r1 != NULL; r1 = r1->next) {
 805                 for (r2 = i2->range; r2 != NULL; r2 = r2->next) {
 806                         if (r2->to > r1->from && r2->from < r1->to) {
 807                                 if (r2->from <= r1->from)
 808                                         return r1->from;
 809                                 else
 810                                         return r2->from;
 811                         }
 812                 }
 813         }
 814
 815         return -1;
 816 }
 817
 818 /**
 819  * mono_linterval_split
 820  *
 821  *   Split L at POS and store the newly created intervals into L1 and L2. POS becomes
 822  * part of L2.
 823  */
 824 void
 825 mono_linterval_split (MonoCompile *cfg, MonoLiveInterval *interval, MonoLiveInterval **i1, MonoLiveInterval **i2, int pos)
 826 {
 827         MonoLiveRange2 *r;
 828
 829         g_assert (pos > interval->range->from && pos <= interval->last_range->to);
 830
 831         *i1 = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
 832         *i2 = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
 833
 834         for (r = interval->range; r; r = r->next) {
 835                 if (pos > r->to) {
 836                         /* Add it to the first child */
 837                         mono_linterval_add_range (cfg, *i1, r->from, r->to);
 838                 } else if (pos > r->from && pos <= r->to) {
 839                         /* Split at pos */
 840                         mono_linterval_add_range (cfg, *i1, r->from, pos - 1);
 841                         mono_linterval_add_range (cfg, *i2, pos, r->to);
 842                 } else {
 843                         /* Add it to the second child */
 844                         mono_linterval_add_range (cfg, *i2, r->from, r->to);
 845                 }
 846         }
 847 }
 848
 849 #ifdef ENABLE_LIVENESS2
 850
 851 #if 0
 852 #define LIVENESS_DEBUG(a) do { a; } while (0)
 853 #else
 854 #define LIVENESS_DEBUG(a)
 855 #endif
 856
 857 static inline void
 858 update_liveness2 (MonoCompile *cfg, MonoInst *ins, gboolean set_volatile, int inst_num, gint32 *last_use)
 859 {
 860         const char *spec = INS_INFO (ins->opcode);
 861         int sreg;
 862
 863         LIVENESS_DEBUG (printf ("\t%x: ", inst_num); mono_print_ins (ins));
 864
 865         if (ins->opcode == OP_NOP)
 866                 return;
 867
 868         /* DREG */
 869         if ((spec [MONO_INST_DEST] != ' ') && get_vreg_to_inst (cfg, ins->dreg)) {
 870                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 871                 int idx = var->inst_c0;
 872                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 873
 874                 if (MONO_IS_STORE_MEMBASE (ins)) {
 875                         if (last_use [idx] == 0) {
 876                                 LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", ins->dreg, inst_num));
 877                                 last_use [idx] = inst_num;
 878                         }
 879                 } else {
 880                         if (last_use [idx] > 0) {
 881                                 LIVENESS_DEBUG (printf ("\tadd range to R%d: [%x, %x)\n", ins->dreg, inst_num, last_use [idx]));
 882                                 mono_linterval_add_range (cfg, vi->interval, inst_num, last_use [idx]);
 883                                 last_use [idx] = 0;
 884                         }
 885                         else {
 886                                 /* Try dead code elimination */
 887                                 if ((var != cfg->ret) && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)) && ((ins->opcode == OP_ICONST) || (ins->opcode == OP_I8CONST) || (ins->opcode == OP_R8CONST)) && !(var->flags & MONO_INST_VOLATILE)) {
 888                                         LIVENESS_DEBUG (printf ("\tdead def of R%d, eliminated\n", ins->dreg));
 889                                         ins->opcode = OP_NOP;
 890                                         ins->dreg = ins->sreg1 = ins->sreg2 = -1;
 891                                         return;
 892                                 }
 893
 894                                 LIVENESS_DEBUG (printf ("\tdead def of R%d, add range to R%d: [%x, %x]\n", ins->dreg, ins->dreg, inst_num, inst_num + 1));
 895                                 mono_linterval_add_range (cfg, vi->interval, inst_num, inst_num + 1);
 896                         }
 897                 }
 898         }
 899
 900         /* SREG1 */
 901         sreg = ins->sreg1;
 902         if ((spec [MONO_INST_SRC1] != ' ') && get_vreg_to_inst (cfg, sreg)) {
 903                 MonoInst *var = get_vreg_to_inst (cfg, sreg);
 904                 int idx = var->inst_c0;
 905
 906                 if (last_use [idx] == 0) {
 907                         LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", sreg, inst_num));
 908                         last_use [idx] = inst_num;
 909                 }
 910         }
 911
 912         /* SREG2 */
 913         sreg = ins->sreg2;
 914         if ((spec [MONO_INST_SRC2] != ' ') && get_vreg_to_inst (cfg, sreg)) {
 915                 MonoInst *var = get_vreg_to_inst (cfg, sreg);
 916                 int idx = var->inst_c0;
 917
 918                 if (last_use [idx] == 0) {
 919                         LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", sreg, inst_num));
 920                         last_use [idx] = inst_num;
 921                 }
 922         }
 923 }
 924
 925 static void
 926 mono_analyze_liveness2 (MonoCompile *cfg)
 927 {
 928         int bnum, idx, i, j, nins, rem, max, max_vars, block_from, block_to, pos, reverse_len;
 929         gint32 *last_use;
 930         static guint32 disabled = -1;
 931         MonoInst **reverse;
 932
 933         if (disabled == -1)
 934                 disabled = getenv ("DISABLED") != NULL;
 935
 936         if (disabled)
 937                 return;
 938
 939         LIVENESS_DEBUG (printf ("LIVENESS 2 %s\n", mono_method_full_name (cfg->method, TRUE)));
 940
 941         /*
 942         if (strstr (cfg->method->name, "test_") != cfg->method->name)
 943                 return;
 944         */
 945
 946         max_vars = cfg->num_varinfo;
 947         last_use = g_new0 (gint32, max_vars);
 948
 949         reverse_len = 1024;
 950         reverse = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * reverse_len);
 951
 952         for (idx = 0; idx < max_vars; ++idx) {
 953                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 954
 955                 vi->interval = mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
 956         }
 957
 958         /*
 959          * Process bblocks in reverse order, so the addition of new live ranges
 960          * to the intervals is faster.
 961          */
 962         for (bnum = cfg->num_bblocks - 1; bnum >= 0; --bnum) {
 963                 MonoBasicBlock *bb = cfg->bblocks [bnum];
 964                 MonoInst *ins;
 965
 966                 block_from = (bb->dfn << 16) + 1; /* so pos > 0 */
 967                 if (bnum < cfg->num_bblocks - 1)
 968                         /* Beginning of the next bblock */
 969                         block_to = (cfg->bblocks [bnum + 1]->dfn << 16) + 1;
 970                 else
 971                         block_to = (bb->dfn << 16) + 0xffff;
 972
 973                 LIVENESS_DEBUG (printf ("LIVENESS BLOCK BB%d:\n", bb->block_num));
 974
 975                 memset (last_use, 0, max_vars * sizeof (gint32));
 976
 977                 /* For variables in bb->live_out, set last_use to block_to */
 978
 979                 rem = max_vars % BITS_PER_CHUNK;
 980                 max = ((max_vars + (BITS_PER_CHUNK -1)) / BITS_PER_CHUNK);
 981                 for (j = 0; j < max; ++j) {
 982                         gsize bits_out;
 983                         int k;
 984
 985                         bits_out = mono_bitset_get_fast (bb->live_out_set, j);
 986                         k = (j * BITS_PER_CHUNK);
 987                         while (bits_out) {
 988                                 if (bits_out & 1) {
 989                                         LIVENESS_DEBUG (printf ("Var R%d live at exit, set last_use to %x\n", cfg->varinfo [k]->dreg, block_to));
 990                                         last_use [k] = block_to;
 991                                 }
 992                                 bits_out >>= 1;
 993                                 k ++;
 994                         }
 995                 }
 996
 997                 if (cfg->ret)
 998                         last_use [cfg->ret->inst_c0] = block_to;
 999
1000                 for (nins = 0, pos = block_from, ins = bb->code; ins; ins = ins->next, ++nins, ++pos) {
1001                         if (nins >= reverse_len) {
1002                                 int new_reverse_len = reverse_len * 2;
1003                                 MonoInst **new_reverse = mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * new_reverse_len);
1004                                 memcpy (new_reverse, reverse, sizeof (MonoInst*) * reverse_len);
1005                                 reverse = new_reverse;
1006                                 reverse_len = new_reverse_len;
1007                         }
1008
1009                         reverse [nins] = ins;
1010                 }
1011
1012                 /* Process instructions backwards */
1013                 for (i = nins - 1; i >= 0; --i) {
1014                         MonoInst *ins = (MonoInst*)reverse [i];
1015
1016                         update_liveness2 (cfg, ins, FALSE, pos, last_use);
1017
1018                         pos --;
1019                 }
1020
1021                 for (idx = 0; idx < max_vars; ++idx) {
1022                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
1023
1024                         if (last_use [idx] != 0) {
1025                                 /* Live at exit, not written -> live on enter */
1026                                 LIVENESS_DEBUG (printf ("Var R%d live at enter, add range to R%d: [%x, %x)\n", cfg->varinfo [idx]->dreg, cfg->varinfo [idx]->dreg, block_from, last_use [idx]));
1027                                 mono_linterval_add_range (cfg, vi->interval, block_from, last_use [idx]);
1028                         }
1029                 }
1030         }
1031
1032         /*
1033          * Arguments need to have their live ranges extended to the beginning of
1034          * the method to account for the arg reg/memory -> global register copies
1035          * in the prolog (bug #74992).
1036          */
1037         for (i = 0; i < max_vars; i ++) {
1038                 MonoMethodVar *vi = MONO_VARINFO (cfg, i);
1039                 if (cfg->varinfo [vi->idx]->opcode == OP_ARG)
1040                         mono_linterval_add_range (cfg, vi->interval, 0, 1);
1041         }
1042
1043 #if 0
1044         for (idx = 0; idx < max_vars; ++idx) {
1045                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
1046
1047                 LIVENESS_DEBUG (printf ("LIVENESS R%d: ", cfg->varinfo [idx]->dreg));
1048                 LIVENESS_DEBUG (mono_linterval_print (vi->interval));
1049                 LIVENESS_DEBUG (printf ("\n"));
1050         }
1051 #endif
1052
1053         g_free (last_use);
1054 }
1055
1056 #endif
1057
1058 static void
1059 update_used (MonoCompile *cfg, MonoInst *inst, MonoBitSet *used)
1060 {
1061         int arity = mono_burg_arity [inst->opcode];
1062
1063         if (arity)
1064                 update_used (cfg, inst->inst_i0, used);
1065
1066         if (arity > 1)
1067                 update_used (cfg, inst->inst_i1, used);
1068
1069         if (inst->ssa_op & MONO_SSA_LOAD_STORE) {
1070                 if (inst->ssa_op == MONO_SSA_LOAD) {
1071                         int idx = inst->inst_i0->inst_c0;
1072
1073                         mono_bitset_set_fast (used, idx);
1074                 }
1075         }
1076 }
1077
1078 /**
1079  * optimize_initlocals:
1080  *
1081  * Try to optimize away some of the redundant initialization code inserted because of
1082  * 'locals init' using the liveness information.
1083  */
1084 static void
1085 optimize_initlocals (MonoCompile *cfg)
1086 {
1087         MonoBitSet *used;
1088         MonoInst *ins;
1089         MonoBasicBlock *initlocals_bb;
1090
1091         used = mono_bitset_new (cfg->num_varinfo, 0);
1092
1093         mono_bitset_clear_all (used);
1094         initlocals_bb = cfg->bb_entry->next_bb;
1095         MONO_BB_FOR_EACH_INS (initlocals_bb, ins)
1096                 update_used (cfg, ins, used);
1097
1098         MONO_BB_FOR_EACH_INS (initlocals_bb, ins) {
1099                 if (ins->ssa_op == MONO_SSA_STORE) {
1100                         int idx = ins->inst_i0->inst_c0;
1101                         MonoInst *var = cfg->varinfo [idx];
1102
1103                         if (var && !mono_bitset_test_fast (used, idx) && !mono_bitset_test_fast (initlocals_bb->live_out_set, var->inst_c0) && (var != cfg->ret) && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
1104                                 if (ins->inst_i1 && ((ins->inst_i1->opcode == OP_ICONST) || (ins->inst_i1->opcode == OP_I8CONST))) {
1105                                         NULLIFY_INS (ins);
1106                                         ins->ssa_op = MONO_SSA_NOP;
1107                                         MONO_VARINFO (cfg, var->inst_c0)->spill_costs -= 1;
1108                                 }
1109                         }
1110                 }
1111         }
1112
1113         g_free (used);
1114 }
1115