mono/mini/liveness.c

   1 /**
   2  * \file
   3  * liveness analysis
   4  *
   5  * Author:
   6  *   Dietmar Maurer (dietmar@ximian.com)
   7  *
   8  * (C) 2002 Ximian, Inc.
   9  * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
  10  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  11  */
  12
  13 #include <config.h>
  14 #include <mono/utils/mono-compiler.h>
  15
  16 #ifndef DISABLE_JIT
  17
  18 #include "mini.h"
  19
  20 #define SPILL_COST_INCREMENT (1 << (bb->nesting << 1))
  21
  22 #define DEBUG_LIVENESS
  23
  24 #define BITS_PER_CHUNK MONO_BITSET_BITS_PER_CHUNK
  25
  26 #define BB_ID_SHIFT 18
  27
  28 /*
  29  * The liveness2 pass can't handle long vars on 32 bit platforms because the component
  30  * vars have the same 'idx'.
  31  */
  32 #if SIZEOF_REGISTER == 8
  33 #define ENABLE_LIVENESS2
  34 #endif
  35
  36 #ifdef ENABLE_LIVENESS2
  37 static void mono_analyze_liveness2 (MonoCompile *cfg);
  38 #endif
  39
  40
  41 #define INLINE_SIZE 16
  42
  43 typedef struct {
  44         int capacity;
  45         union {
  46                 gpointer data [INLINE_SIZE];
  47                 GHashTable *hashtable;
  48         };
  49 } MonoPtrSet;
  50
  51 static void
  52 mono_ptrset_init (MonoPtrSet *set)
  53 {
  54         set->capacity = 0;
  55 }
  56
  57 static void
  58 mono_ptrset_destroy (MonoPtrSet *set)
  59 {
  60         if (set->capacity > INLINE_SIZE)
  61                 g_hash_table_destroy (set->hashtable);
  62 }
  63
  64 static void
  65 mono_ptrset_add (MonoPtrSet *set, gpointer val)
  66 {
  67         //switch to hashtable
  68         if (set->capacity == INLINE_SIZE) {
  69                 GHashTable *tmp = g_hash_table_new (NULL, NULL);
  70                 for (int i = 0; i < INLINE_SIZE; ++i)
  71                         g_hash_table_insert (tmp, set->data [i], set->data [i]);
  72                 set->hashtable = tmp;
  73                 ++set->capacity;
  74         }
  75
  76         if (set->capacity > INLINE_SIZE) {
  77                 g_hash_table_insert (set->hashtable, val, val);
  78         } else {
  79                 set->data [set->capacity] = val;
  80                 ++set->capacity;
  81         }
  82 }
  83
  84 static gboolean
  85 mono_ptrset_contains (MonoPtrSet *set, gpointer val)
  86 {
  87         if (set->capacity <= INLINE_SIZE) {
  88                 for (int i = 0; i < set->capacity; ++i) {
  89                         if (set->data [i] == val)
  90                                 return TRUE;
  91                 }
  92                 return FALSE;
  93         }
  94
  95         return g_hash_table_lookup (set->hashtable, val) != NULL;
  96 }
  97
  98
  99 static void
 100 optimize_initlocals (MonoCompile *cfg);
 101
 102 /* mono_bitset_mp_new:
 103  *
 104  * allocates a MonoBitSet inside a memory pool
 105  */
 106 static MonoBitSet*
 107 mono_bitset_mp_new (MonoMemPool *mp, guint32 size, guint32 max_size)
 108 {
 109         guint8 *mem = (guint8 *)mono_mempool_alloc0 (mp, size);
 110         return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
 111 }
 112
 113 static MonoBitSet*
 114 mono_bitset_mp_new_noinit (MonoMemPool *mp, guint32 size, guint32 max_size)
 115 {
 116         guint8 *mem = (guint8 *)mono_mempool_alloc (mp, size);
 117         return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
 118 }
 119
 120 G_GNUC_UNUSED static void
 121 mono_bitset_print (MonoBitSet *set)
 122 {
 123         int i;
 124         gboolean first = TRUE;
 125
 126         printf ("{");
 127         for (i = 0; i < mono_bitset_size (set); i++) {
 128
 129                 if (mono_bitset_test (set, i)) {
 130                         if (!first)
 131                                 printf (", ");
 132                         printf ("%d", i);
 133                         first = FALSE;
 134                 }
 135         }
 136         printf ("}\n");
 137 }
 138
 139 static void
 140 visit_bb (MonoCompile *cfg, MonoBasicBlock *bb, MonoPtrSet *visited)
 141 {
 142         int i;
 143         MonoInst *ins;
 144
 145         if (mono_ptrset_contains (visited, bb))
 146                 return;
 147
 148         for (ins = bb->code; ins; ins = ins->next) {
 149                 const char *spec = INS_INFO (ins->opcode);
 150                 int regtype, srcindex, sreg, num_sregs;
 151                 int sregs [MONO_MAX_SRC_REGS];
 152
 153                 if (ins->opcode == OP_NOP)
 154                         continue;
 155
 156                 /* DREG */
 157                 regtype = spec [MONO_INST_DEST];
 158                 g_assert (((ins->dreg == -1) && (regtype == ' ')) || ((ins->dreg != -1) && (regtype != ' ')));
 159
 160                 if ((ins->dreg != -1) && get_vreg_to_inst (cfg, ins->dreg)) {
 161                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 162                         int idx = var->inst_c0;
 163                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 164
 165                         cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
 166                         if (SIZEOF_REGISTER == 4 && (var->type == STACK_I8 || (var->type == STACK_R8 && COMPILE_SOFT_FLOAT (cfg)))) {
 167                                 /* Make the component vregs volatile as well (#612206) */
 168                                 get_vreg_to_inst (cfg, MONO_LVREG_LS (var->dreg))->flags |= MONO_INST_VOLATILE;
 169                                 get_vreg_to_inst (cfg, MONO_LVREG_MS (var->dreg))->flags |= MONO_INST_VOLATILE;
 170                         }
 171                 }
 172
 173                 /* SREGS */
 174                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 175                 for (srcindex = 0; srcindex < num_sregs; ++srcindex) {
 176                         sreg = sregs [srcindex];
 177
 178                         g_assert (sreg != -1);
 179                         if (get_vreg_to_inst (cfg, sreg)) {
 180                                 MonoInst *var = get_vreg_to_inst (cfg, sreg);
 181                                 int idx = var->inst_c0;
 182                                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 183
 184                                 cfg->varinfo [vi->idx]->flags |= MONO_INST_VOLATILE;
 185                                 if (SIZEOF_REGISTER == 4 && (var->type == STACK_I8 || (var->type == STACK_R8 && COMPILE_SOFT_FLOAT (cfg)))) {
 186                                         /* Make the component vregs volatile as well (#612206) */
 187                                         get_vreg_to_inst (cfg, MONO_LVREG_LS (var->dreg))->flags |= MONO_INST_VOLATILE;
 188                                         get_vreg_to_inst (cfg, MONO_LVREG_MS (var->dreg))->flags |= MONO_INST_VOLATILE;
 189                                 }
 190                         }
 191                 }
 192         }
 193
 194         mono_ptrset_add (visited, bb);
 195
 196         /*
 197          * Need to visit all bblocks reachable from this one since they can be
 198          * reached during exception handling.
 199          */
 200         for (i = 0; i < bb->out_count; ++i) {
 201                 visit_bb (cfg, bb->out_bb [i], visited);
 202         }
 203 }
 204
 205 void
 206 mono_liveness_handle_exception_clauses (MonoCompile *cfg)
 207 {
 208         MonoBasicBlock *bb;
 209         MonoMethodHeader *header = cfg->header;
 210         MonoExceptionClause *clause, *clause2;
 211         int i, j;
 212         gboolean *outer_try;
 213
 214         /*
 215          * Determine which clauses are outer try clauses, i.e. they are not contained in any
 216          * other non-try clause.
 217          */
 218         outer_try = (gboolean *)mono_mempool_alloc0 (cfg->mempool, sizeof (gboolean) * header->num_clauses);
 219         for (i = 0; i < header->num_clauses; ++i)
 220                 outer_try [i] = TRUE;
 221         /* Iterate over the clauses backward, so outer clauses come first */
 222         /* This avoids doing an O(2) search, since we can determine when inner clauses end */
 223         for (i = header->num_clauses - 1; i >= 0; --i) {
 224                 clause = &header->clauses [i];
 225
 226                 if (clause->flags != 0) {
 227                         outer_try [i] = TRUE;
 228                         /* Iterate over inner clauses */
 229                         for (j = i - 1; j >= 0; --j) {
 230                                 clause2 = &header->clauses [j];
 231
 232                                 if (clause2->flags == 0 && MONO_OFFSET_IN_HANDLER (clause, clause2->try_offset)) {
 233                                         outer_try [j] = FALSE;
 234                                         break;
 235                                 }
 236                                 if (clause2->try_offset < clause->try_offset)
 237                                         /* End of inner clauses */
 238                                         break;
 239                         }
 240                 }
 241         }
 242
 243         MonoPtrSet visited;
 244         mono_ptrset_init (&visited);
 245         /*
 246          * Variables in exception handler register cannot be allocated to registers
 247          * so make them volatile. See bug #42136. This will not be neccessary when
 248          * the back ends could guarantee that the variables will be in the
 249          * correct registers when a handler is called.
 250          * This includes try blocks too, since a variable in a try block might be
 251          * accessed after an exception handler has been run.
 252          */
 253         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 254
 255                 if (bb->region == -1)
 256                         continue;
 257
 258                 if (MONO_BBLOCK_IS_IN_REGION (bb, MONO_REGION_TRY) && outer_try [MONO_REGION_CLAUSE_INDEX (bb->region)])
 259                         continue;
 260
 261                 if (cfg->verbose_level > 2)
 262                         printf ("pessimize variables in bb %d.\n", bb->block_num);
 263
 264                 visit_bb (cfg, bb, &visited);
 265         }
 266         mono_ptrset_destroy (&visited);
 267 }
 268
 269 static void
 270 update_live_range (MonoMethodVar *var, int abs_pos)
 271 {
 272         if (var->range.first_use.abs_pos > abs_pos)
 273                 var->range.first_use.abs_pos = abs_pos;
 274
 275         if (var->range.last_use.abs_pos < abs_pos)
 276                 var->range.last_use.abs_pos = abs_pos;
 277 }
 278
 279 static void
 280 analyze_liveness_bb (MonoCompile *cfg, MonoBasicBlock *bb)
 281 {
 282         MonoInst *ins;
 283         int sreg, inst_num;
 284         MonoMethodVar *vars = cfg->vars;
 285         guint32 abs_pos = (bb->dfn << BB_ID_SHIFT);
 286
 287         /* Start inst_num from > 0, so last_use.abs_pos is only 0 for dead variables */
 288         for (inst_num = 2, ins = bb->code; ins; ins = ins->next, inst_num += 2) {
 289                 const char *spec = INS_INFO (ins->opcode);
 290                 int num_sregs, i;
 291                 int sregs [MONO_MAX_SRC_REGS];
 292
 293 #ifdef DEBUG_LIVENESS
 294                 if (cfg->verbose_level > 1) {
 295                         mono_print_ins_index (1, ins);
 296                 }
 297 #endif
 298
 299                 if (ins->opcode == OP_NOP)
 300                         continue;
 301
 302                 if (ins->opcode == OP_LDADDR) {
 303                         MonoInst *var = (MonoInst *)ins->inst_p0;
 304                         int idx = var->inst_c0;
 305                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 306
 307 #ifdef DEBUG_LIVENESS
 308                         if (cfg->verbose_level > 1)
 309                                 printf ("\tGEN: R%d(%d)\n", var->dreg, idx);
 310 #endif
 311                         update_live_range (&vars [idx], abs_pos + inst_num);
 312                         if (!mono_bitset_test_fast (bb->kill_set, idx))
 313                                 mono_bitset_set_fast (bb->gen_set, idx);
 314                         vi->spill_costs += SPILL_COST_INCREMENT;
 315                 }
 316
 317                 /* SREGs must come first, so MOVE r <- r is handled correctly */
 318                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 319                 for (i = 0; i < num_sregs; ++i) {
 320                         sreg = sregs [i];
 321                         if ((spec [MONO_INST_SRC1 + i] != ' ') && get_vreg_to_inst (cfg, sreg)) {
 322                                 MonoInst *var = get_vreg_to_inst (cfg, sreg);
 323                                 int idx = var->inst_c0;
 324                                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 325
 326 #ifdef DEBUG_LIVENESS
 327                                 if (cfg->verbose_level > 1)
 328                                         printf ("\tGEN: R%d(%d)\n", sreg, idx);
 329 #endif
 330                                 update_live_range (&vars [idx], abs_pos + inst_num);
 331                                 if (!mono_bitset_test_fast (bb->kill_set, idx))
 332                                         mono_bitset_set_fast (bb->gen_set, idx);
 333                                 vi->spill_costs += SPILL_COST_INCREMENT;
 334                         }
 335                 }
 336
 337                 /* DREG */
 338                 if ((spec [MONO_INST_DEST] != ' ') && get_vreg_to_inst (cfg, ins->dreg)) {
 339                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 340                         int idx = var->inst_c0;
 341                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 342
 343                         if (MONO_IS_STORE_MEMBASE (ins)) {
 344                                 update_live_range (&vars [idx], abs_pos + inst_num);
 345                                 if (!mono_bitset_test_fast (bb->kill_set, idx))
 346                                         mono_bitset_set_fast (bb->gen_set, idx);
 347                                 vi->spill_costs += SPILL_COST_INCREMENT;
 348                         } else {
 349 #ifdef DEBUG_LIVENESS
 350                                 if (cfg->verbose_level > 1)
 351                                         printf ("\tKILL: R%d(%d)\n", ins->dreg, idx);
 352 #endif
 353                                 update_live_range (&vars [idx], abs_pos + inst_num + 1);
 354                                 mono_bitset_set_fast (bb->kill_set, idx);
 355                                 vi->spill_costs += SPILL_COST_INCREMENT;
 356                         }
 357                 }
 358         }
 359 }
 360
 361 /* generic liveness analysis code. CFG specific parts are
 362  * in update_gen_kill_set()
 363  */
 364 void
 365 mono_analyze_liveness (MonoCompile *cfg)
 366 {
 367         MonoBitSet *old_live_out_set;
 368         int i, j, max_vars = cfg->num_varinfo;
 369         int out_iter;
 370         gboolean *in_worklist;
 371         MonoBasicBlock **worklist;
 372         guint32 l_end;
 373         int bitsize;
 374
 375 #ifdef DEBUG_LIVENESS
 376         if (cfg->verbose_level > 1)
 377                 printf ("\nLIVENESS:\n");
 378 #endif
 379
 380         g_assert (!(cfg->comp_done & MONO_COMP_LIVENESS));
 381
 382         cfg->comp_done |= MONO_COMP_LIVENESS;
 383
 384         if (max_vars == 0)
 385                 return;
 386
 387         bitsize = mono_bitset_alloc_size (max_vars, 0);
 388
 389         for (i = 0; i < max_vars; i ++) {
 390                 MONO_VARINFO (cfg, i)->range.first_use.abs_pos = ~ 0;
 391                 MONO_VARINFO (cfg, i)->range.last_use .abs_pos =   0;
 392                 MONO_VARINFO (cfg, i)->spill_costs = 0;
 393         }
 394
 395         for (i = 0; i < cfg->num_bblocks; ++i) {
 396                 MonoBasicBlock *bb = cfg->bblocks [i];
 397
 398                 bb->gen_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 399                 bb->kill_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 400
 401 #ifdef DEBUG_LIVENESS
 402                 if (cfg->verbose_level > 1) {
 403                         printf ("BLOCK BB%d (", bb->block_num);
 404                         for (j = 0; j < bb->out_count; j++)
 405                                 printf ("BB%d, ", bb->out_bb [j]->block_num);
 406
 407                         printf ("):\n");
 408                 }
 409 #endif
 410
 411                 analyze_liveness_bb (cfg, bb);
 412
 413 #ifdef DEBUG_LIVENESS
 414                 if (cfg->verbose_level > 1) {
 415                         printf ("GEN  BB%d: ", bb->block_num); mono_bitset_print (bb->gen_set);
 416                         printf ("KILL BB%d: ", bb->block_num); mono_bitset_print (bb->kill_set);
 417                 }
 418 #endif
 419         }
 420
 421         old_live_out_set = mono_bitset_new (max_vars, 0);
 422         in_worklist = g_new0 (gboolean, cfg->num_bblocks + 1);
 423
 424         worklist = g_new (MonoBasicBlock *, cfg->num_bblocks + 1);
 425         l_end = 0;
 426
 427         /*
 428          * This is a backward dataflow analysis problem, so we process blocks in
 429          * decreasing dfn order, this speeds up the iteration.
 430          */
 431         for (i = 0; i < cfg->num_bblocks; i ++) {
 432                 MonoBasicBlock *bb = cfg->bblocks [i];
 433
 434                 worklist [l_end ++] = bb;
 435                 in_worklist [bb->dfn] = TRUE;
 436
 437                 /* Initialized later */
 438                 bb->live_in_set = NULL;
 439                 bb->live_out_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 440         }
 441
 442         out_iter = 0;
 443
 444         if (cfg->verbose_level > 1)
 445                 printf ("\nITERATION:\n");
 446
 447         while (l_end != 0) {
 448                 MonoBasicBlock *bb = worklist [--l_end];
 449                 MonoBasicBlock *out_bb;
 450                 gboolean changed;
 451
 452                 in_worklist [bb->dfn] = FALSE;
 453
 454 #ifdef DEBUG_LIVENESS
 455                 if (cfg->verbose_level > 1) {
 456                         printf ("P: BB%d(%d): IN: ", bb->block_num, bb->dfn);
 457                         for (j = 0; j < bb->in_count; ++j)
 458                                 printf ("BB%d ", bb->in_bb [j]->block_num);
 459                         printf ("OUT:");
 460                         for (j = 0; j < bb->out_count; ++j)
 461                                 printf ("BB%d ", bb->out_bb [j]->block_num);
 462                         printf ("\n");
 463                 }
 464 #endif
 465
 466
 467                 if (bb->out_count == 0)
 468                         continue;
 469
 470                 out_iter ++;
 471
 472                 if (!bb->live_in_set) {
 473                         /* First pass over this bblock */
 474                         changed = TRUE;
 475                 }
 476                 else {
 477                         changed = FALSE;
 478                         mono_bitset_copyto_fast (bb->live_out_set, old_live_out_set);
 479                 }
 480
 481                 for (j = 0; j < bb->out_count; j++) {
 482                         out_bb = bb->out_bb [j];
 483
 484                         if (!out_bb->live_in_set) {
 485                                 out_bb->live_in_set = mono_bitset_mp_new_noinit (cfg->mempool, bitsize, max_vars);
 486
 487                                 mono_bitset_copyto_fast (out_bb->live_out_set, out_bb->live_in_set);
 488                                 mono_bitset_sub_fast (out_bb->live_in_set, out_bb->kill_set);
 489                                 mono_bitset_union_fast (out_bb->live_in_set, out_bb->gen_set);
 490                         }
 491
 492                         // FIXME: Do this somewhere else
 493                         if (bb->last_ins && bb->last_ins->opcode == OP_NOT_REACHED) {
 494                         } else {
 495                                 mono_bitset_union_fast (bb->live_out_set, out_bb->live_in_set);
 496                         }
 497                 }
 498
 499                 if (changed || !mono_bitset_equal (old_live_out_set, bb->live_out_set)) {
 500                         if (!bb->live_in_set)
 501                                 bb->live_in_set = mono_bitset_mp_new_noinit (cfg->mempool, bitsize, max_vars);
 502                         mono_bitset_copyto_fast (bb->live_out_set, bb->live_in_set);
 503                         mono_bitset_sub_fast (bb->live_in_set, bb->kill_set);
 504                         mono_bitset_union_fast (bb->live_in_set, bb->gen_set);
 505
 506                         for (j = 0; j < bb->in_count; j++) {
 507                                 MonoBasicBlock *in_bb = bb->in_bb [j];
 508                                 /*
 509                                  * Some basic blocks do not seem to be in the
 510                                  * cfg->bblocks array...
 511                                  */
 512                                 if (in_bb->gen_set && !in_worklist [in_bb->dfn]) {
 513 #ifdef DEBUG_LIVENESS
 514                                         if (cfg->verbose_level > 1)
 515                                                 printf ("\tADD: %d\n", in_bb->block_num);
 516 #endif
 517                                         /*
 518                                          * Put the block at the top of the stack, so it
 519                                          * will be processed right away.
 520                                          */
 521                                         worklist [l_end ++] = in_bb;
 522                                         in_worklist [in_bb->dfn] = TRUE;
 523                                 }
 524                         }
 525                 }
 526
 527                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
 528                         printf ("\tLIVE IN  BB%d: ", bb->block_num);
 529                         mono_bitset_print (bb->live_in_set);
 530                 }
 531         }
 532
 533 #ifdef DEBUG_LIVENESS
 534         if (cfg->verbose_level > 1)
 535                 printf ("IT: %d %d.\n", cfg->num_bblocks, out_iter);
 536 #endif
 537
 538         mono_bitset_free (old_live_out_set);
 539
 540         g_free (worklist);
 541         g_free (in_worklist);
 542
 543         /* Compute live_in_set for bblocks skipped earlier */
 544         for (i = 0; i < cfg->num_bblocks; ++i) {
 545                 MonoBasicBlock *bb = cfg->bblocks [i];
 546
 547                 if (!bb->live_in_set) {
 548                         bb->live_in_set = mono_bitset_mp_new (cfg->mempool, bitsize, max_vars);
 549
 550                         mono_bitset_copyto_fast (bb->live_out_set, bb->live_in_set);
 551                         mono_bitset_sub_fast (bb->live_in_set, bb->kill_set);
 552                         mono_bitset_union_fast (bb->live_in_set, bb->gen_set);
 553                 }
 554         }
 555
 556         for (i = 0; i < cfg->num_bblocks; ++i) {
 557                 MonoBasicBlock *bb = cfg->bblocks [i];
 558                 guint32 max;
 559                 guint32 abs_pos = (bb->dfn << BB_ID_SHIFT);
 560                 MonoMethodVar *vars = cfg->vars;
 561
 562                 if (!bb->live_out_set)
 563                         continue;
 564
 565                 max = ((max_vars + (BITS_PER_CHUNK -1)) / BITS_PER_CHUNK);
 566                 for (j = 0; j < max; ++j) {
 567                         gsize bits_in;
 568                         gsize bits_out;
 569                         int k;
 570
 571                         bits_in = mono_bitset_get_fast (bb->live_in_set, j);
 572                         bits_out = mono_bitset_get_fast (bb->live_out_set, j);
 573
 574                         k = (j * BITS_PER_CHUNK);
 575                         while ((bits_in || bits_out)) {
 576                                 if (bits_in & 1)
 577                                         update_live_range (&vars [k], abs_pos + 0);
 578                                 if (bits_out & 1)
 579                                         update_live_range (&vars [k], abs_pos + ((1 << BB_ID_SHIFT) - 1));
 580                                 bits_in >>= 1;
 581                                 bits_out >>= 1;
 582                                 k ++;
 583                         }
 584                 }
 585         }
 586
 587         /*
 588          * Arguments need to have their live ranges extended to the beginning of
 589          * the method to account for the arg reg/memory -> global register copies
 590          * in the prolog (bug #74992).
 591          */
 592
 593         for (i = 0; i < max_vars; i ++) {
 594                 MonoMethodVar *vi = MONO_VARINFO (cfg, i);
 595                 if (cfg->varinfo [vi->idx]->opcode == OP_ARG) {
 596                         if (vi->range.last_use.abs_pos == 0 && !(cfg->varinfo [vi->idx]->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 597                                 /*
 598                                  * Can't eliminate the this variable in gshared code, since
 599                                  * it is needed during exception handling to identify the
 600                                  * method.
 601                                  * It is better to check for this here instead of marking the variable
 602                                  * VOLATILE, since that would prevent it from being allocated to
 603                                  * registers.
 604                                  */
 605                                  if (!cfg->disable_deadce_vars && !(cfg->gshared && mono_method_signature_internal (cfg->method)->hasthis && cfg->varinfo [vi->idx] == cfg->args [0]))
 606                                          cfg->varinfo [vi->idx]->flags |= MONO_INST_IS_DEAD;
 607                         }
 608                         vi->range.first_use.abs_pos = 0;
 609                 }
 610         }
 611
 612 #ifdef DEBUG_LIVENESS
 613         if (cfg->verbose_level > 1) {
 614                 for (i = cfg->num_bblocks - 1; i >= 0; i--) {
 615                         MonoBasicBlock *bb = cfg->bblocks [i];
 616
 617                         printf ("LIVE IN  BB%d: ", bb->block_num);
 618                         mono_bitset_print (bb->live_in_set);
 619                         printf ("LIVE OUT BB%d: ", bb->block_num);
 620                         mono_bitset_print (bb->live_out_set);
 621                 }
 622
 623                 for (i = 0; i < max_vars; i ++) {
 624                         MonoMethodVar *vi = MONO_VARINFO (cfg, i);
 625
 626                         printf ("V%d: [0x%x - 0x%x]\n", i, vi->range.first_use.abs_pos, vi->range.last_use.abs_pos);
 627                 }
 628         }
 629 #endif
 630
 631         if (!cfg->disable_initlocals_opt)
 632                 optimize_initlocals (cfg);
 633
 634 #ifdef ENABLE_LIVENESS2
 635         /* This improves code size by about 5% but slows down compilation too much */
 636         if (cfg->compile_aot)
 637                 mono_analyze_liveness2 (cfg);
 638 #endif
 639 }
 640
 641 /**
 642  * optimize_initlocals:
 643  *
 644  * Try to optimize away some of the redundant initialization code inserted because of
 645  * 'locals init' using the liveness information.
 646  */
 647 static void
 648 optimize_initlocals (MonoCompile *cfg)
 649 {
 650         MonoBitSet *used;
 651         MonoInst *ins;
 652         MonoBasicBlock *initlocals_bb;
 653
 654         used = mono_bitset_new (cfg->next_vreg + 1, 0);
 655
 656         mono_bitset_clear_all (used);
 657         initlocals_bb = cfg->bb_entry->next_bb;
 658         for (ins = initlocals_bb->code; ins; ins = ins->next) {
 659                 int num_sregs, i;
 660                 int sregs [MONO_MAX_SRC_REGS];
 661
 662                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 663                 for (i = 0; i < num_sregs; ++i)
 664                         mono_bitset_set_fast (used, sregs [i]);
 665
 666                 if (MONO_IS_STORE_MEMBASE (ins))
 667                         mono_bitset_set_fast (used, ins->dreg);
 668         }
 669
 670         for (ins = initlocals_bb->code; ins; ins = ins->next) {
 671                 const char *spec = INS_INFO (ins->opcode);
 672
 673                 /* Look for statements whose dest is not used in this bblock and not live on exit. */
 674                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 675                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 676
 677                         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))) {
 678                                 //printf ("DEAD: "); mono_print_ins (ins);
 679                                 if (cfg->disable_initlocals_opt_refs && var->type == STACK_OBJ)
 680                                         continue;
 681                                 if ((ins->opcode == OP_ICONST) || (ins->opcode == OP_I8CONST) || (ins->opcode == OP_R8CONST) || (ins->opcode == OP_R4CONST)) {
 682                                         NULLIFY_INS (ins);
 683                                         MONO_VARINFO (cfg, var->inst_c0)->spill_costs -= 1;
 684                                         /*
 685                                          * We should shorten the liveness interval of these vars as well, but
 686                                          * don't have enough info to do that.
 687                                          */
 688                                 }
 689                         }
 690                 }
 691         }
 692
 693         g_free (used);
 694 }
 695
 696 void
 697 mono_linterval_add_range (MonoCompile *cfg, MonoLiveInterval *interval, int from, int to)
 698 {
 699         MonoLiveRange2 *prev_range, *next_range, *new_range;
 700
 701         g_assert (to >= from);
 702
 703         /* Optimize for extending the first interval backwards */
 704         if (G_LIKELY (interval->range && (interval->range->from > from) && (interval->range->from == to))) {
 705                 interval->range->from = from;
 706                 return;
 707         }
 708
 709         /* Find a place in the list for the new range */
 710         prev_range = NULL;
 711         next_range = interval->range;
 712         while ((next_range != NULL) && (next_range->from <= from)) {
 713                 prev_range = next_range;
 714                 next_range = next_range->next;
 715         }
 716
 717         if (prev_range && prev_range->to == from) {
 718                 /* Merge with previous */
 719                 prev_range->to = to;
 720         } else if (next_range && next_range->from == to) {
 721                 /* Merge with previous */
 722                 next_range->from = from;
 723         } else {
 724                 /* Insert it */
 725                 new_range = (MonoLiveRange2 *)mono_mempool_alloc (cfg->mempool, sizeof (MonoLiveRange2));
 726                 new_range->from = from;
 727                 new_range->to = to;
 728                 new_range->next = NULL;
 729
 730                 if (prev_range)
 731                         prev_range->next = new_range;
 732                 else
 733                         interval->range = new_range;
 734                 if (next_range)
 735                         new_range->next = next_range;
 736                 else
 737                         interval->last_range = new_range;
 738         }
 739
 740         /* FIXME: Merge intersecting ranges */
 741 }
 742
 743 void
 744 mono_linterval_print (MonoLiveInterval *interval)
 745 {
 746         MonoLiveRange2 *range;
 747
 748         for (range = interval->range; range != NULL; range = range->next)
 749                 printf ("[%x-%x] ", range->from, range->to);
 750 }
 751
 752 void
 753 mono_linterval_print_nl (MonoLiveInterval *interval)
 754 {
 755         mono_linterval_print (interval);
 756         printf ("\n");
 757 }
 758
 759 /**
 760  * mono_linterval_convers:
 761  *
 762  *   Return whenever INTERVAL covers the position POS.
 763  */
 764 gboolean
 765 mono_linterval_covers (MonoLiveInterval *interval, int pos)
 766 {
 767         MonoLiveRange2 *range;
 768
 769         for (range = interval->range; range != NULL; range = range->next) {
 770                 if (pos >= range->from && pos <= range->to)
 771                         return TRUE;
 772                 if (range->from > pos)
 773                         return FALSE;
 774         }
 775
 776         return FALSE;
 777 }
 778
 779 /**
 780  * mono_linterval_get_intersect_pos:
 781  *
 782  *   Determine whenever I1 and I2 intersect, and if they do, return the first
 783  * point of intersection. Otherwise, return -1.
 784  */
 785 gint32
 786 mono_linterval_get_intersect_pos (MonoLiveInterval *i1, MonoLiveInterval *i2)
 787 {
 788         MonoLiveRange2 *r1, *r2;
 789
 790         /* FIXME: Optimize this */
 791         for (r1 = i1->range; r1 != NULL; r1 = r1->next) {
 792                 for (r2 = i2->range; r2 != NULL; r2 = r2->next) {
 793                         if (r2->to > r1->from && r2->from < r1->to) {
 794                                 if (r2->from <= r1->from)
 795                                         return r1->from;
 796                                 else
 797                                         return r2->from;
 798                         }
 799                 }
 800         }
 801
 802         return -1;
 803 }
 804
 805 /**
 806  * mono_linterval_split
 807  *
 808  *   Split L at POS and store the newly created intervals into L1 and L2. POS becomes
 809  * part of L2.
 810  */
 811 void
 812 mono_linterval_split (MonoCompile *cfg, MonoLiveInterval *interval, MonoLiveInterval **i1, MonoLiveInterval **i2, int pos)
 813 {
 814         MonoLiveRange2 *r;
 815
 816         g_assert (pos > interval->range->from && pos <= interval->last_range->to);
 817
 818         *i1 = (MonoLiveInterval *)mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
 819         *i2 = (MonoLiveInterval *)mono_mempool_alloc0 (cfg->mempool, sizeof (MonoLiveInterval));
 820
 821         for (r = interval->range; r; r = r->next) {
 822                 if (pos > r->to) {
 823                         /* Add it to the first child */
 824                         mono_linterval_add_range (cfg, *i1, r->from, r->to);
 825                 } else if (pos > r->from && pos <= r->to) {
 826                         /* Split at pos */
 827                         mono_linterval_add_range (cfg, *i1, r->from, pos - 1);
 828                         mono_linterval_add_range (cfg, *i2, pos, r->to);
 829                 } else {
 830                         /* Add it to the second child */
 831                         mono_linterval_add_range (cfg, *i2, r->from, r->to);
 832                 }
 833         }
 834 }
 835
 836 #if 1
 837 #define LIVENESS_DEBUG(a) do { if (cfg->verbose_level > 1) do { a; } while (0); } while (0)
 838 #define ENABLE_LIVENESS_DEBUG 1
 839 #else
 840 #define LIVENESS_DEBUG(a)
 841 #endif
 842
 843 #ifdef ENABLE_LIVENESS2
 844
 845 static void
 846 update_liveness2 (MonoCompile *cfg, MonoInst *ins, gboolean set_volatile, int inst_num, gint32 *last_use)
 847 {
 848         const char *spec = INS_INFO (ins->opcode);
 849         int sreg;
 850         int num_sregs, i;
 851         int sregs [MONO_MAX_SRC_REGS];
 852
 853         LIVENESS_DEBUG (printf ("\t%x: ", inst_num); mono_print_ins (ins));
 854
 855         if (ins->opcode == OP_NOP || ins->opcode == OP_IL_SEQ_POINT)
 856                 return;
 857
 858         /* DREG */
 859         if ((spec [MONO_INST_DEST] != ' ') && get_vreg_to_inst (cfg, ins->dreg)) {
 860                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 861                 int idx = var->inst_c0;
 862                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 863
 864                 if (MONO_IS_STORE_MEMBASE (ins)) {
 865                         if (last_use [idx] == 0) {
 866                                 LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", ins->dreg, inst_num));
 867                                 last_use [idx] = inst_num;
 868                         }
 869                 } else {
 870                         if (last_use [idx] > 0) {
 871                                 LIVENESS_DEBUG (printf ("\tadd range to R%d: [%x, %x)\n", ins->dreg, inst_num, last_use [idx]));
 872                                 mono_linterval_add_range (cfg, vi->interval, inst_num, last_use [idx]);
 873                                 last_use [idx] = 0;
 874                         }
 875                         else {
 876                                 /* Try dead code elimination */
 877                                 if (!cfg->disable_deadce_vars && (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)) {
 878                                         LIVENESS_DEBUG (printf ("\tdead def of R%d, eliminated\n", ins->dreg));
 879                                         NULLIFY_INS (ins);
 880                                         return;
 881                                 } else {
 882                                         int inst_num_add = 1;
 883                                         MonoInst *next = ins->next;
 884                                         while (next && next->opcode == OP_IL_SEQ_POINT) {
 885                                                 inst_num_add++;
 886                                                 next = next->next;
 887                                         }
 888
 889                                         LIVENESS_DEBUG (printf ("\tdead def of R%d, add range to R%d: [%x, %x]\n", ins->dreg, ins->dreg, inst_num, inst_num + inst_num_add));
 890                                         mono_linterval_add_range (cfg, vi->interval, inst_num, inst_num + inst_num_add);
 891                                 }
 892                         }
 893                 }
 894         }
 895
 896         /* SREGs */
 897         num_sregs = mono_inst_get_src_registers (ins, sregs);
 898         for (i = 0; i < num_sregs; ++i) {
 899                 sreg = sregs [i];
 900                 if ((spec [MONO_INST_SRC1 + i] != ' ') && get_vreg_to_inst (cfg, sreg)) {
 901                         MonoInst *var = get_vreg_to_inst (cfg, sreg);
 902                         int idx = var->inst_c0;
 903
 904                         if (last_use [idx] == 0) {
 905                                 LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", sreg, inst_num));
 906                                 last_use [idx] = inst_num;
 907                         }
 908                 }
 909         }
 910 }
 911
 912 static void
 913 mono_analyze_liveness2 (MonoCompile *cfg)
 914 {
 915         int bnum, idx, i, j, nins, max, max_vars, block_from, block_to, pos;
 916         gint32 *last_use;
 917         static guint32 disabled = -1;
 918
 919         if (disabled == -1)
 920                 disabled = g_hasenv ("DISABLED");
 921
 922         if (disabled)
 923                 return;
 924
 925         if (cfg->num_bblocks >= (1 << (32 - BB_ID_SHIFT - 1)))
 926                 /* Ranges would overflow */
 927                 return;
 928
 929         for (bnum = cfg->num_bblocks - 1; bnum >= 0; --bnum) {
 930                 MonoBasicBlock *bb = cfg->bblocks [bnum];
 931                 MonoInst *ins;
 932
 933                 nins = 0;
 934                 for (nins = 0, ins = bb->code; ins; ins = ins->next, ++nins)
 935                         nins ++;
 936
 937                 if (nins >= ((1 << BB_ID_SHIFT) - 1))
 938                         /* Ranges would overflow */
 939                         return;
 940         }
 941
 942         LIVENESS_DEBUG (printf ("LIVENESS 2 %s\n", mono_method_full_name (cfg->method, TRUE)));
 943
 944         /*
 945         if (strstr (cfg->method->name, "test_") != cfg->method->name)
 946                 return;
 947         */
 948
 949         max_vars = cfg->num_varinfo;
 950         last_use = g_new0 (gint32, max_vars);
 951
 952         for (idx = 0; idx < max_vars; ++idx) {
 953                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
 954
 955                 vi->interval = (MonoLiveInterval *)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 << BB_ID_SHIFT) + 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 << BB_ID_SHIFT) + 1;
 970                 else
 971                         block_to = (bb->dfn << BB_ID_SHIFT) + ((1 << BB_ID_SHIFT) - 1);
 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                 max = ((max_vars + (BITS_PER_CHUNK -1)) / BITS_PER_CHUNK);
 980                 for (j = 0; j < max; ++j) {
 981                         gsize bits_out;
 982                         int k;
 983
 984                         bits_out = mono_bitset_get_fast (bb->live_out_set, j);
 985                         k = (j * BITS_PER_CHUNK);
 986                         while (bits_out) {
 987                                 if (bits_out & 1) {
 988                                         LIVENESS_DEBUG (printf ("Var R%d live at exit, set last_use to %x\n", cfg->varinfo [k]->dreg, block_to));
 989                                         last_use [k] = block_to;
 990                                 }
 991                                 bits_out >>= 1;
 992                                 k ++;
 993                         }
 994                 }
 995
 996                 if (cfg->ret)
 997                         last_use [cfg->ret->inst_c0] = block_to;
 998
 999                 pos = block_from + 1;
1000                 MONO_BB_FOR_EACH_INS (bb, ins) pos++;
1001
1002                 /* Process instructions backwards */
1003                 MONO_BB_FOR_EACH_INS_REVERSE (bb, ins) {
1004                         update_liveness2 (cfg, ins, FALSE, pos, last_use);
1005                         pos--;
1006                 }
1007
1008                 for (idx = 0; idx < max_vars; ++idx) {
1009                         MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
1010
1011                         if (last_use [idx] != 0) {
1012                                 /* Live at exit, not written -> live on enter */
1013                                 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]));
1014                                 mono_linterval_add_range (cfg, vi->interval, block_from, last_use [idx]);
1015                         }
1016                 }
1017         }
1018
1019         /*
1020          * Arguments need to have their live ranges extended to the beginning of
1021          * the method to account for the arg reg/memory -> global register copies
1022          * in the prolog (bug #74992).
1023          */
1024         for (i = 0; i < max_vars; i ++) {
1025                 MonoMethodVar *vi = MONO_VARINFO (cfg, i);
1026                 if (cfg->varinfo [vi->idx]->opcode == OP_ARG)
1027                         mono_linterval_add_range (cfg, vi->interval, 0, 1);
1028         }
1029
1030 #if 0
1031         for (idx = 0; idx < max_vars; ++idx) {
1032                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
1033
1034                 LIVENESS_DEBUG (printf ("LIVENESS R%d: ", cfg->varinfo [idx]->dreg));
1035                 LIVENESS_DEBUG (mono_linterval_print (vi->interval));
1036                 LIVENESS_DEBUG (printf ("\n"));
1037         }
1038 #endif
1039
1040         g_free (last_use);
1041 }
1042
1043 #endif
1044
1045 static void
1046 update_liveness_gc (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, gint32 *last_use, MonoMethodVar **vreg_to_varinfo, GSList **callsites)
1047 {
1048         if (ins->opcode == OP_GC_LIVENESS_DEF || ins->opcode == OP_GC_LIVENESS_USE) {
1049                 int vreg = ins->inst_c1;
1050                 MonoMethodVar *vi = vreg_to_varinfo [vreg];
1051                 int idx = vi->idx;
1052                 int pc_offset = ins->backend.pc_offset;
1053
1054                 LIVENESS_DEBUG (printf ("\t%x: ", pc_offset); mono_print_ins (ins));
1055
1056                 if (ins->opcode == OP_GC_LIVENESS_DEF) {
1057                         if (last_use [idx] > 0) {
1058                                 LIVENESS_DEBUG (printf ("\tadd range to R%d: [%x, %x)\n", vreg, pc_offset, last_use [idx]));
1059                                 last_use [idx] = 0;
1060                         }
1061                 } else {
1062                         if (last_use [idx] == 0) {
1063                                 LIVENESS_DEBUG (printf ("\tlast use of R%d set to %x\n", vreg, pc_offset));
1064                                 last_use [idx] = pc_offset;
1065                         }
1066                 }
1067         } else if (ins->opcode == OP_GC_PARAM_SLOT_LIVENESS_DEF) {
1068                 GCCallSite *last;
1069
1070                 /* Add it to the last callsite */
1071                 g_assert (*callsites);
1072                 last = (GCCallSite *)(*callsites)->data;
1073                 last->param_slots = g_slist_prepend_mempool (cfg->mempool, last->param_slots, ins);
1074         } else if (ins->flags & MONO_INST_GC_CALLSITE) {
1075                 GCCallSite *callsite = (GCCallSite *)mono_mempool_alloc0 (cfg->mempool, sizeof (GCCallSite));
1076                 int i;
1077
1078                 LIVENESS_DEBUG (printf ("\t%x: ", ins->backend.pc_offset); mono_print_ins (ins));
1079                 LIVENESS_DEBUG (printf ("\t\tlive: "));
1080
1081                 callsite->bb = bb;
1082                 callsite->liveness = (guint8 *)mono_mempool_alloc0 (cfg->mempool, ALIGN_TO (cfg->num_varinfo, 8) / 8);
1083                 callsite->pc_offset = ins->backend.pc_offset;
1084                 for (i = 0; i < cfg->num_varinfo; ++i) {
1085                         if (last_use [i] != 0) {
1086                                 LIVENESS_DEBUG (printf ("R%d", MONO_VARINFO (cfg, i)->vreg));
1087                                 callsite->liveness [i / 8] |= (1 << (i % 8));
1088                         }
1089                 }
1090                 LIVENESS_DEBUG (printf ("\n"));
1091                 *callsites = g_slist_prepend_mempool (cfg->mempool, *callsites, callsite);
1092         }
1093 }
1094
1095 static int
1096 get_vreg_from_var (MonoCompile *cfg, MonoInst *var)
1097 {
1098         if (var->opcode == OP_REGVAR)
1099                 /* dreg contains a hreg, but inst_c0 still contains the var index */
1100                 return MONO_VARINFO (cfg, var->inst_c0)->vreg;
1101         else
1102                 /* dreg still contains the vreg */
1103                 return var->dreg;
1104 }
1105
1106 /*
1107  * mono_analyze_liveness_gc:
1108  *
1109  *   Compute liveness bitmaps for each call site.
1110  * This function is a modified version of mono_analyze_liveness2 ().
1111  */
1112 void
1113 mono_analyze_liveness_gc (MonoCompile *cfg)
1114 {
1115         int idx, i, j, nins, max, max_vars, block_from, block_to, pos, reverse_len;
1116         gint32 *last_use;
1117         MonoInst **reverse;
1118         MonoMethodVar **vreg_to_varinfo = NULL;
1119         MonoBasicBlock *bb;
1120         GSList *callsites;
1121
1122         LIVENESS_DEBUG (printf ("\n------------ GC LIVENESS: ----------\n"));
1123
1124         max_vars = cfg->num_varinfo;
1125         last_use = g_new0 (gint32, max_vars);
1126
1127         /*
1128          * var->inst_c0 no longer contains the variable index, so compute a mapping now.
1129          */
1130         vreg_to_varinfo = g_new0 (MonoMethodVar*, cfg->next_vreg);
1131         for (idx = 0; idx < max_vars; ++idx) {
1132                 MonoMethodVar *vi = MONO_VARINFO (cfg, idx);
1133
1134                 vreg_to_varinfo [vi->vreg] = vi;
1135         }
1136
1137         reverse_len = 1024;
1138         reverse = (MonoInst **)mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * reverse_len);
1139
1140         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
1141                 MonoInst *ins;
1142
1143                 block_from = bb->real_native_offset;
1144                 block_to = bb->native_offset + bb->native_length;
1145
1146                 LIVENESS_DEBUG (printf ("GC LIVENESS BB%d:\n", bb->block_num));
1147
1148                 if (!bb->code)
1149                         continue;
1150
1151                 memset (last_use, 0, max_vars * sizeof (gint32));
1152
1153                 /* For variables in bb->live_out, set last_use to block_to */
1154
1155                 max = ((max_vars + (BITS_PER_CHUNK -1)) / BITS_PER_CHUNK);
1156                 for (j = 0; j < max; ++j) {
1157                         gsize bits_out;
1158                         int k;
1159
1160                         if (!bb->live_out_set)
1161                                 /* The variables used in this bblock are volatile anyway */
1162                                 continue;
1163
1164                         bits_out = mono_bitset_get_fast (bb->live_out_set, j);
1165                         k = (j * BITS_PER_CHUNK);
1166                         while (bits_out) {
1167                                 if ((bits_out & 1) && cfg->varinfo [k]->flags & MONO_INST_GC_TRACK) {
1168                                         int vreg = get_vreg_from_var (cfg, cfg->varinfo [k]);
1169                                         LIVENESS_DEBUG (printf ("Var R%d live at exit, last_use set to %x.\n", vreg, block_to));
1170                                         last_use [k] = block_to;
1171                                 }
1172                                 bits_out >>= 1;
1173                                 k ++;
1174                         }
1175                 }
1176
1177                 for (nins = 0, pos = block_from, ins = bb->code; ins; ins = ins->next, ++nins, ++pos) {
1178                         if (nins >= reverse_len) {
1179                                 int new_reverse_len = reverse_len * 2;
1180                                 MonoInst **new_reverse = (MonoInst **)mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * new_reverse_len);
1181                                 memcpy (new_reverse, reverse, sizeof (MonoInst*) * reverse_len);
1182                                 reverse = new_reverse;
1183                                 reverse_len = new_reverse_len;
1184                         }
1185
1186                         reverse [nins] = ins;
1187                 }
1188
1189                 /* Process instructions backwards */
1190                 callsites = NULL;
1191                 for (i = nins - 1; i >= 0; --i) {
1192                         MonoInst *ins = (MonoInst*)reverse [i];
1193
1194                         update_liveness_gc (cfg, bb, ins, last_use, vreg_to_varinfo, &callsites);
1195                 }
1196                 /* The callsites should already be sorted by pc offset because we added them backwards */
1197                 bb->gc_callsites = callsites;
1198         }
1199
1200         g_free (last_use);
1201         g_free (vreg_to_varinfo);
1202 }
1203
1204 #else /* !DISABLE_JIT */
1205
1206 MONO_EMPTY_SOURCE_FILE (liveness);
1207
1208 #endif /* !DISABLE_JIT */