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