mono/mini/ssa2.c

   1 /*
   2  * ssa.c: Static single assign form support for the JIT compiler.
   3  *
   4  * Author:
   5  *    Dietmar Maurer (dietmar@ximian.com)
   6  *
   7  * (C) 2003 Ximian, Inc.
   8  */
   9 #include <string.h>
  10 #include <mono/metadata/debug-helpers.h>
  11
  12 #define NEW_IR
  13 #include "mini.h"
  14
  15 #define USE_ORIGINAL_VARS
  16 #define CREATE_PRUNED_SSA
  17
  18 //#define DEBUG_SSA 1
  19
  20 #define NEW_PHI(cfg,dest,val) do {      \
  21                 (dest) = mono_mempool_alloc0 ((cfg)->mempool, sizeof (MonoInst));       \
  22                 (dest)->opcode = OP_PHI;        \
  23                 (dest)->inst_c0 = (val);        \
  24         (dest)->dreg = (dest)->sreg1 = (dest)->sreg2 = -1; \
  25         } while (0)
  26
  27 #define NEW_ICONST(cfg,dest,val) do {   \
  28                 (dest) = mono_mempool_alloc0 ((cfg)->mempool, sizeof (MonoInst));       \
  29                 (dest)->opcode = OP_ICONST;     \
  30                 (dest)->inst_c0 = (val);        \
  31                 (dest)->type = STACK_I4;        \
  32         (dest)->dreg = (dest)->sreg1 = (dest)->sreg2 = -1; \
  33         } while (0)
  34
  35 typedef struct {
  36         MonoBasicBlock *bb;
  37         MonoInst *inst;
  38 } MonoVarUsageInfo;
  39
  40 static inline GList*
  41 g_list_prepend_mempool (GList* l, MonoMemPool* mp, gpointer datum)
  42 {
  43         GList* n = mono_mempool_alloc (mp, sizeof (GList));
  44         n->next = l;
  45         n->prev = NULL;
  46         n->data = datum;
  47         return n;
  48 }
  49
  50 static void
  51 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
  52 {
  53         int i;
  54
  55         for (i = 0; i < bb->out_count; i++) {
  56                 if (bb->out_bb [i] == target) {
  57                         bb->out_bb [i] = bb->out_bb [--bb->out_count];
  58                         break;
  59                 }
  60         }
  61         for (i = 0; i < target->in_count; i++) {
  62                 if (target->in_bb [i] == bb) {
  63                         target->in_bb [i] = target->in_bb [--target->in_count];
  64                         break;
  65
  66                 }
  67         }
  68 }
  69
  70 static void
  71 unlink_unused_bblocks (MonoCompile *cfg)
  72 {
  73         int i, j;
  74         MonoBasicBlock *bb;
  75
  76         g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
  77
  78         if (G_UNLIKELY (cfg->verbose_level > 1))
  79                 printf ("\nUNLINK UNUSED BBLOCKS:\n");
  80
  81         for (bb = cfg->bb_entry; bb && bb->next_bb;) {
  82                 if (!(bb->next_bb->flags & BB_REACHABLE)) {
  83                         bb->next_bb = bb->next_bb->next_bb;
  84                 } else
  85                         bb = bb->next_bb;
  86         }
  87
  88         for (i = 1; i < cfg->num_bblocks; i++) {
  89                 bb = cfg->bblocks [i];
  90
  91                 if (!(bb->flags & BB_REACHABLE)) {
  92                         for (j = 0; j < bb->in_count; j++) {
  93                                 unlink_target (bb->in_bb [j], bb);
  94                         }
  95                         for (j = 0; j < bb->out_count; j++) {
  96                                 unlink_target (bb, bb->out_bb [j]);
  97                         }
  98                         if (G_UNLIKELY (cfg->verbose_level > 1))
  99                                 printf ("\tUnlinked BB%d\n", bb->block_num);
 100                 }
 101
 102         }
 103 }
 104
 105 /**
 106  * remove_bb_from_phis:
 107  *
 108  *   Remove BB from the PHI statements in TARGET.
 109  */
 110 static void
 111 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
 112 {
 113         MonoInst *ins;
 114         int i, j;
 115
 116         for (i = 0; i < target->in_count; i++) {
 117                 if (target->in_bb [i] == bb) {
 118                         break;
 119                 }
 120         }
 121         g_assert (i < target->in_count);
 122
 123         for (ins = target->code; ins; ins = ins->next) {
 124                 if (MONO_IS_PHI (ins)) {
 125                         for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
 126                                 ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
 127                         ins->inst_phi_args [0] --;
 128                 }
 129                 else
 130                         break;
 131         }
 132 }
 133
 134 static inline int
 135 op_phi_to_move (int opcode)
 136 {
 137         switch (opcode) {
 138         case OP_PHI:
 139                 return OP_MOVE;
 140         case OP_FPHI:
 141                 return OP_FMOVE;
 142         case OP_VPHI:
 143                 return OP_VMOVE;
 144         default:
 145                 g_assert_not_reached ();
 146         }
 147
 148         return -1;
 149 }
 150
 151 static inline void
 152 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
 153 {
 154         MonoMethodVar *info;
 155         MonoVarUsageInfo *ui = mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
 156
 157         info = MONO_VARINFO (cfg, var->inst_c0);
 158
 159         ui->bb = bb;
 160         ui->inst = ins;
 161         info->uses = g_list_prepend_mempool (info->uses, cfg->mempool, ui);
 162 }
 163
 164 typedef struct {
 165         MonoInst *var;
 166         int idx;
 167 } RenameInfo;
 168
 169 /**
 170  * mono_ssa_rename_vars2:
 171  *
 172  *  Implement renaming of SSA variables. Also compute def-use information in parallel.
 173  * @stack_history points to an area of memory which can be used for storing changes
 174  * made to the stack, so they can be reverted later.
 175  */
 176 static void
 177 mono_ssa_rename_vars2 (MonoCompile *cfg, int max_vars, MonoBasicBlock *bb, gboolean *originals_used, MonoInst **stack,  guint32 *lvreg_stack, gboolean *lvreg_defined, RenameInfo *stack_history, int stack_history_size)
 178 {
 179         MonoInst *ins, *new_var;
 180         int i, j, idx;
 181         GSList *tmp;
 182         int stack_history_len = 0;
 183
 184         if (cfg->verbose_level >= 4)
 185                 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
 186
 187         /* First pass: Create new vars */
 188         for (ins = bb->code; ins; ins = ins->next) {
 189                 const char *spec = INS_INFO (ins->opcode);
 190
 191 #ifdef DEBUG_SSA
 192                 printf ("\tProcessing "); mono_print_ins (ins);
 193 #endif
 194                 if (ins->opcode == OP_NOP)
 195                         continue;
 196
 197                 /* SREG1 */
 198                 if (spec [MONO_INST_SRC1] != ' ') {
 199                         MonoInst *var = get_vreg_to_inst (cfg, ins->sreg1);
 200                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 201                                 int idx = var->inst_c0;
 202                                 if (stack [idx]) {
 203                                         if (var->opcode != OP_ARG)
 204                                                 g_assert (stack [idx]);
 205                                         ins->sreg1 = stack [idx]->dreg;
 206                                         record_use (cfg, stack [idx], bb, ins);
 207                                 }
 208                                 else
 209                                         record_use (cfg, var, bb, ins);
 210                         }
 211                         else if (G_UNLIKELY (!var && lvreg_stack [ins->sreg1]))
 212                                 ins->sreg1 = lvreg_stack [ins->sreg1];
 213                 }
 214
 215                 /* SREG2 */
 216                 if (spec [MONO_INST_SRC2] != ' ') {
 217                         MonoInst *var = get_vreg_to_inst (cfg, ins->sreg2);
 218                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 219                                 int idx = var->inst_c0;
 220                                 if (stack [idx]) {
 221                                         if (var->opcode != OP_ARG)
 222                                                 g_assert (stack [idx]);
 223
 224                                         ins->sreg2 = stack [idx]->dreg;
 225                                         record_use (cfg, stack [idx], bb, ins);
 226                                 }
 227                                 else
 228                                         record_use (cfg, var, bb, ins);
 229                         }
 230                         else if (G_UNLIKELY (!var && lvreg_stack [ins->sreg2]))
 231                                 ins->sreg2 = lvreg_stack [ins->sreg2];
 232                 }
 233
 234                 if (MONO_IS_STORE_MEMBASE (ins)) {
 235                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 236                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 237                                 int idx = var->inst_c0;
 238                                 if (stack [idx]) {
 239                                         if (var->opcode != OP_ARG)
 240                                                 g_assert (stack [idx]);
 241                                         ins->dreg = stack [idx]->dreg;
 242                                         record_use (cfg, stack [idx], bb, ins);
 243                                 }
 244                                 else
 245                                         record_use (cfg, var, bb, ins);
 246                         }
 247                         else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
 248                                 ins->dreg = lvreg_stack [ins->dreg];
 249                 }
 250
 251                 /* DREG */
 252                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 253                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 254                         MonoMethodVar *info;
 255
 256                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 257                                 idx = var->inst_c0;
 258                                 g_assert (idx < max_vars);
 259
 260                                 if (var->opcode == OP_ARG)
 261                                         originals_used [idx] = TRUE;
 262
 263                                 /* FIXME: */
 264                                 g_assert (stack_history_len < stack_history_size);
 265                                 stack_history [stack_history_len].var = stack [idx];
 266                                 stack_history [stack_history_len].idx = idx;
 267                                 stack_history_len ++;
 268
 269                                 if (originals_used [idx]) {
 270                                         new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
 271                                         new_var->flags = var->flags;
 272                                         MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
 273
 274                                         if (cfg->verbose_level >= 4)
 275                                                 printf ("  R%d -> R%d\n", var->dreg, new_var->dreg);
 276
 277                                         stack [idx] = new_var;
 278
 279                                         ins->dreg = new_var->dreg;
 280                                         var = new_var;
 281                                 }
 282                                 else {
 283                                         stack [idx] = var;
 284                                         originals_used [idx] = TRUE;
 285                                 }
 286
 287                                 info = MONO_VARINFO (cfg, var->inst_c0);
 288                                 info->def = ins;
 289                                 info->def_bb = bb;
 290                         }
 291                         else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
 292                                 /* Perform renaming for local vregs */
 293                                 lvreg_stack [ins->dreg] = mono_alloc_preg (cfg);
 294                                 ins->dreg = lvreg_stack [ins->dreg];
 295                         }
 296                         else
 297                                 lvreg_defined [ins->dreg] = TRUE;
 298                 }
 299
 300 #ifdef DEBUG_SSA
 301                 printf ("\tAfter processing "); mono_print_ins (ins);
 302 #endif
 303
 304         }
 305
 306         /* Rename PHI arguments in succeeding bblocks */
 307         for (i = 0; i < bb->out_count; i++) {
 308                 MonoBasicBlock *n = bb->out_bb [i];
 309
 310                 for (j = 0; j < n->in_count; j++)
 311                         if (n->in_bb [j] == bb)
 312                                 break;
 313
 314                 for (ins = n->code; ins; ins = ins->next) {
 315                         if (MONO_IS_PHI (ins)) {
 316                                 idx = ins->inst_c0;
 317                                 if (stack [idx])
 318                                         new_var = stack [idx];
 319                                 else
 320                                         new_var = cfg->varinfo [idx];
 321 #ifdef DEBUG_SSA
 322                                 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
 323 #endif
 324                                 ins->inst_phi_args [j + 1] = new_var->dreg;
 325                                 record_use (cfg,  new_var, n, ins);
 326                                 if (G_UNLIKELY (cfg->verbose_level >= 4))
 327                                         printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
 328                         }
 329                         else
 330                                 /* The phi nodes are at the beginning of the bblock */
 331                                 break;
 332                 }
 333         }
 334
 335         if (bb->dominated) {
 336                 for (tmp = bb->dominated; tmp; tmp = tmp->next) {
 337                         mono_ssa_rename_vars2 (cfg, max_vars, (MonoBasicBlock *)tmp->data, originals_used, stack, lvreg_stack, lvreg_defined, stack_history + stack_history_len, stack_history_size - stack_history_len);
 338                 }
 339         }
 340
 341         /* Restore stack */
 342         for (i = stack_history_len - 1; i >= 0; i--) {
 343                 stack [stack_history [i].idx] = stack_history [i].var;
 344         }
 345
 346         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 347 }
 348
 349 void
 350 mono_ssa_compute2 (MonoCompile *cfg)
 351 {
 352         int i, j, idx, bitsize;
 353         MonoBitSet *set;
 354         MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
 355         MonoInst *ins, **stack;
 356         guint8 *buf, *buf_start;
 357         RenameInfo *stack_history;
 358         int stack_history_size;
 359         gboolean *originals;
 360         guint32 *lvreg_stack;
 361         gboolean *lvreg_defined;
 362
 363         g_assert (!(cfg->comp_done & MONO_COMP_SSA));
 364
 365         /* we dont support methods containing exception clauses */
 366         g_assert (mono_method_get_header (cfg->method)->num_clauses == 0);
 367         g_assert (!cfg->disable_ssa);
 368
 369         if (cfg->verbose_level >= 4)
 370                 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
 371
 372 #ifdef CREATE_PRUNED_SSA
 373         /* we need liveness for pruned SSA */
 374         if (!(cfg->comp_done & MONO_COMP_LIVENESS))
 375                 mono_analyze_liveness (cfg);
 376 #endif
 377
 378         mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
 379
 380         bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
 381         buf = buf_start = g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
 382
 383         for (i = 0; i < cfg->num_varinfo; ++i) {
 384                 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
 385                 buf += bitsize;
 386                 vinfo [i].idx = i;
 387                 /* implicit reference at start */
 388                 mono_bitset_set_fast (vinfo [i].def_in, 0);
 389         }
 390
 391         for (i = 0; i < cfg->num_bblocks; ++i) {
 392                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 393                         if (ins->opcode == OP_NOP)
 394                                 continue;
 395
 396                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 397                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 398                         }
 399                 }
 400         }
 401
 402         /* insert phi functions */
 403         for (i = 0; i < cfg->num_varinfo; ++i) {
 404                 MonoInst *var = cfg->varinfo [i];
 405
 406 #if SIZEOF_VOID_P == 4
 407                 if (var->type == STACK_I8)
 408                         continue;
 409 #endif
 410                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 411                         continue;
 412
 413                 /* Most variables have only one definition */
 414                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 415                         continue;
 416
 417                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 418
 419                 if (cfg->verbose_level >= 4) {
 420                         if (mono_bitset_count (set) > 0) {
 421                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 422                                 mono_blockset_print (cfg, set, "", -1);
 423                         }
 424                 }
 425
 426                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 427                         MonoBasicBlock *bb = cfg->bblocks [idx];
 428
 429                         /* fixme: create pruned SSA? we would need liveness information for that */
 430
 431                         if (bb == cfg->bb_exit)
 432                                 continue;
 433
 434                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 435                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 436                                 continue;
 437                         }
 438
 439                         NEW_PHI (cfg, ins, i);
 440
 441                         switch (var->type) {
 442                         case STACK_I4:
 443                         case STACK_I8:
 444                         case STACK_PTR:
 445                         case STACK_MP:
 446                         case STACK_OBJ:
 447                                 ins->opcode = OP_PHI;
 448                                 break;
 449                         case STACK_R8:
 450                                 ins->opcode = OP_FPHI;
 451                                 break;
 452                         case STACK_VTYPE:
 453                                 ins->opcode = OP_VPHI;
 454                                 ins->klass = var->klass;
 455                                 break;
 456                         }
 457
 458                         ins->inst_phi_args =  mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 459                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 460
 461                         /* For debugging */
 462                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 463                                 ins->inst_phi_args [j + 1] = -1;
 464
 465                         ins->dreg = cfg->varinfo [i]->dreg;
 466
 467                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 468
 469 #ifdef DEBUG_SSA
 470                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 471 #endif
 472                 }
 473         }
 474
 475         /* free the stuff */
 476         g_free (vinfo);
 477         g_free (buf_start);
 478
 479         /* Renaming phase */
 480
 481         stack = alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 482         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 483
 484         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 485         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 486         stack_history_size = 10240;
 487         stack_history = g_new (RenameInfo, stack_history_size);
 488         originals = g_new0 (gboolean, cfg->num_varinfo);
 489         mono_ssa_rename_vars2 (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 490         g_free (stack_history);
 491         g_free (originals);
 492
 493         if (cfg->verbose_level >= 4)
 494                 printf ("\nEND COMPUTE SSA.\n\n");
 495
 496         cfg->comp_done |= MONO_COMP_SSA;
 497 }
 498
 499 void
 500 mono_ssa_remove2 (MonoCompile *cfg)
 501 {
 502         MonoInst *ins, *var, *move;
 503         int i, j, first;
 504
 505         g_assert (cfg->comp_done & MONO_COMP_SSA);
 506
 507         for (i = 0; i < cfg->num_bblocks; ++i) {
 508                 MonoBasicBlock *bb = cfg->bblocks [i];
 509
 510                 if (cfg->verbose_level >= 4)
 511                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 512
 513                 for (ins = bb->code; ins; ins = ins->next) {
 514                         if (MONO_IS_PHI (ins)) {
 515                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 516                                 var = get_vreg_to_inst (cfg, ins->dreg);
 517
 518                                 /* Check for PHI nodes where all the inputs are the same */
 519                                 first = ins->inst_phi_args [1];
 520
 521                                 for (j = 1; j < bb->in_count; ++j)
 522                                         if (first != ins->inst_phi_args [j + 1])
 523                                                 break;
 524
 525                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 526                                         ins->opcode = op_phi_to_move (ins->opcode);
 527                                         if (ins->opcode == OP_VMOVE)
 528                                                 g_assert (ins->klass);
 529                                         ins->sreg1 = first;
 530                                 } else {
 531                                         for (j = 0; j < bb->in_count; j++) {
 532                                                 MonoBasicBlock *pred = bb->in_bb [j];
 533                                                 int sreg = ins->inst_phi_args [j + 1];
 534
 535                                                 if (cfg->verbose_level >= 4)
 536                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 537                                                 if (var->dreg != sreg) {
 538                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 539                                                         if (move->opcode == OP_VMOVE) {
 540                                                                 g_assert (ins->klass);
 541                                                                 move->klass = ins->klass;
 542                                                         }
 543                                                         move->dreg = var->dreg;
 544                                                         move->sreg1 = sreg;
 545                                                         mono_add_ins_to_end (pred, move);
 546                                                 }
 547                                         }
 548
 549                                         ins->opcode = OP_NOP;
 550                                         ins->dreg = -1;
 551                                 }
 552                         }
 553                 }
 554         }
 555
 556         if (cfg->verbose_level >= 4) {
 557                 for (i = 0; i < cfg->num_bblocks; ++i) {
 558                         MonoBasicBlock *bb = cfg->bblocks [i];
 559
 560                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 561                 }
 562         }
 563
 564         /*
 565          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 566          * the variables if possible. Since the newly introduced SSA variables don't
 567          * have overlapping live ranges (because we don't do agressive optimization), we
 568          * can coalesce them into the original variable.
 569          */
 570
 571         for (i = 0; i < cfg->num_bblocks; ++i) {
 572                 MonoBasicBlock *bb = cfg->bblocks [i];
 573
 574                 for (ins = bb->code; ins; ins = ins->next) {
 575                         const char *spec = INS_INFO (ins->opcode);
 576
 577                         if (ins->opcode == OP_NOP)
 578                                 continue;
 579
 580                         if (spec [MONO_INST_DEST] != ' ') {
 581                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 582
 583                                 if (var) {
 584                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 585
 586                                         /*
 587                                          * The third condition avoids coalescing with variables eliminated
 588                                          * during deadce.
 589                                          */
 590                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 591                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 592                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 593                                         }
 594                                 }
 595                         }
 596
 597                         if (spec [MONO_INST_SRC1] != ' ') {
 598                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg1);
 599
 600                                 if (var) {
 601                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 602
 603                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 604                                                 printf ("COALESCE: R%d -> R%d\n", ins->sreg1, cfg->varinfo [vmv->reg]->dreg);
 605                                                 ins->sreg1 = cfg->varinfo [vmv->reg]->dreg;
 606                                         }
 607                                 }
 608                         }
 609
 610                         if (spec [MONO_INST_SRC2] != ' ') {
 611                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg2);
 612
 613                                 if (var) {
 614                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 615
 616                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 617                                                 printf ("COALESCE: R%d -> R%d\n", ins->sreg2, cfg->varinfo [vmv->reg]->dreg);
 618                                                 ins->sreg2 = cfg->varinfo [vmv->reg]->dreg;
 619                                         }
 620                                 }
 621                         }
 622
 623                 }
 624         }
 625
 626         for (i = 0; i < cfg->num_varinfo; ++i) {
 627                 MONO_VARINFO (cfg, i)->reg = -1;
 628         }
 629
 630         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 631                 unlink_unused_bblocks (cfg);
 632
 633         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 634
 635         cfg->comp_done &= ~MONO_COMP_SSA;
 636 }
 637
 638 static void
 639 mono_ssa_create_def_use (MonoCompile *cfg)
 640 {
 641         MonoBasicBlock *bb;
 642         MonoInst *ins;
 643         int i;
 644
 645         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 646
 647         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 648                 for (ins = bb->code; ins; ins = ins->next) {
 649                         const char *spec = INS_INFO (ins->opcode);
 650                         MonoMethodVar *info;
 651
 652                         if (ins->opcode == OP_NOP)
 653                                 continue;
 654
 655                         /* SREG1 */
 656                         if (spec [MONO_INST_SRC1] != ' ') {
 657                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg1);
 658                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 659                                         record_use (cfg, var, bb, ins);
 660                         }
 661
 662                         /* SREG2 */
 663                         if (spec [MONO_INST_SRC2] != ' ') {
 664                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg2);
 665                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 666                                         record_use (cfg, var, bb, ins);
 667                         }
 668
 669                         if (MONO_IS_STORE_MEMBASE (ins)) {
 670                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 671                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 672                                         record_use (cfg, var, bb, ins);
 673                         }
 674
 675                         if (MONO_IS_PHI (ins)) {
 676                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 677                                         g_assert (ins->inst_phi_args [i] != -1);
 678                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 679                                 }
 680                         }
 681
 682                         /* DREG */
 683                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 684                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 685
 686                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 687                                         info = MONO_VARINFO (cfg, var->inst_c0);
 688                                         info->def = ins;
 689                                         info->def_bb = bb;
 690                                 }
 691                         }
 692                 }
 693         }
 694
 695         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 696 }
 697
 698 static void
 699 mono_ssa_copyprop (MonoCompile *cfg)
 700 {
 701         int i, index;
 702         GList *l;
 703
 704         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 705
 706         for (index = 0; index < cfg->num_varinfo; ++index) {
 707                 MonoInst *var = cfg->varinfo [index];
 708                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 709
 710                 if (info->def && (MONO_IS_MOVE (info->def))) {
 711                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 712
 713                         if (var2 && !(var2->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)) && MONO_VARINFO (cfg, var2->inst_c0)->def && (!MONO_IS_PHI (MONO_VARINFO (cfg, var2->inst_c0)->def))) {
 714                                 /* Rewrite all uses of var to be uses of var2 */
 715                                 int dreg = var->dreg;
 716                                 int sreg1 = var2->dreg;
 717                                 const char *spec;
 718
 719                                 l = info->uses;
 720                                 while (l) {
 721                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 722                                         MonoInst *ins = u->inst;
 723                                         GList *next = l->next;
 724
 725                                         spec = INS_INFO (ins->opcode);
 726
 727                                         if (spec [MONO_INST_SRC1] != ' ' && ins->sreg1 == dreg) {
 728                                                 ins->sreg1 = sreg1;
 729                                         } else if (spec [MONO_INST_SRC2] != ' ' && ins->sreg2 == dreg) {
 730                                                 ins->sreg2 = sreg1;
 731                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 732                                                 ins->dreg = sreg1;
 733                                         } else if (MONO_IS_PHI (ins)) {
 734                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 735                                                         int sreg = ins->inst_phi_args [i];
 736                                                         if (sreg == var->dreg)
 737                                                                 break;
 738                                                 }
 739                                                 g_assert (i > 0);
 740                                                 ins->inst_phi_args [i] = sreg1;
 741                                         }
 742                                         else
 743                                                 g_assert_not_reached ();
 744
 745                                         record_use (cfg, var2, u->bb, ins);
 746
 747                                         l = next;
 748                                 }
 749
 750                                 info->uses = NULL;
 751                         }
 752                 }
 753         }
 754
 755         if (cfg->verbose_level >= 4) {
 756                 MonoBasicBlock *bb;
 757
 758                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 759                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 760         }
 761 }
 762
 763 static int
 764 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 765 {
 766         MonoInst *arg0, *arg1, *c0;
 767         int r1, r2;
 768         gboolean const_args = FALSE;
 769         const char *spec = INS_INFO (ins->opcode);
 770
 771         /* Short-circuit this */
 772         if (ins->opcode == OP_ICONST) {
 773                 *res = ins;
 774                 return 1;
 775         }
 776
 777         if (ins->opcode == OP_NOP)
 778                 return 2;
 779
 780         arg0 = NULL;
 781         if (spec [MONO_INST_SRC1] != ' ') {
 782                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg1);
 783
 784                 r1 = 2;
 785                 arg0 = carray [ins->sreg1];
 786                 if (arg0)
 787                         r1 = 1;
 788                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 789                         r1 = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 790         } else {
 791                 r1 = 2;
 792         }
 793
 794         arg1 = NULL;
 795         if (spec [MONO_INST_SRC2] != ' ') {
 796                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg2);
 797
 798                 r2 = 2;
 799                 arg1 = carray [ins->sreg2];
 800                 if (arg1)
 801                         r2 = 1;
 802                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 803                         r2 = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 804         }
 805         else {
 806                 r2 = 0;
 807         }
 808
 809         c0 = NULL;
 810         if ((spec [MONO_INST_SRC1] != ' ') && (spec [MONO_INST_SRC2] != ' ')) {
 811                 /* Binop */
 812                 const_args = (r1 == 1) && (r2 == 1);
 813         }
 814         else if (spec [MONO_INST_SRC1] != ' ') {
 815                 /* Unop */
 816                 const_args = (r1 == 1);
 817         }
 818
 819         if (const_args) {
 820                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 821                         // Cached value
 822                         *res = carray [ins->dreg];
 823                         return 1;
 824                 }
 825                 c0 = mono_constant_fold_ins2 (cfg, ins, arg0, arg1, FALSE);
 826                 if (c0) {
 827                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 828                                 printf ("\t cfold -> ");
 829                                 mono_print_ins (c0);
 830                         }
 831                         *res = c0;
 832                         return 1;
 833                 }
 834                 else
 835                         /* Can't cfold this ins */
 836                         return 2;
 837         }
 838
 839         if ((spec [MONO_INST_SRC1] != ' ') && (spec [MONO_INST_SRC2] != ' ')) {
 840                 /* Binop */
 841                 if ((r1 == 2) || (r2 == 2))
 842                         return 2;
 843                 else
 844                         return 0;
 845         }
 846         else if (spec [MONO_INST_SRC1] != ' ') {
 847                 /* Unop */
 848                 if (r1 == 2)
 849                         return 2;
 850                 else
 851                         return 0;
 852         }
 853         else
 854                 return 2;
 855 }
 856
 857 static inline void
 858 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 859 {
 860         if (info->cpstate >= state)
 861                 return;
 862
 863         info->cpstate = state;
 864
 865         if (G_UNLIKELY (cfg->verbose_level > 1))
 866                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 867
 868         if (state == 1)
 869                 g_assert (c0);
 870
 871         carray [cfg->varinfo [info->idx]->dreg] = c0;
 872
 873         if (!g_list_find (*cvars, info)) {
 874                 *cvars = g_list_prepend (*cvars, info);
 875         }
 876 }
 877
 878 static inline void
 879 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 880 {
 881         if (G_UNLIKELY (cfg->verbose_level > 1))
 882                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 883
 884     if (!(bb->flags &  BB_REACHABLE)) {
 885             bb->flags |= BB_REACHABLE;
 886                 *bblist = g_list_prepend (*bblist, bb);
 887         }
 888 }
 889
 890 static void
 891 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 892 {
 893         const char *spec = INS_INFO (ins->opcode);
 894
 895         if (ins->opcode == OP_NOP)
 896                 return;
 897
 898         if (cfg->verbose_level > 1)
 899                 mono_print_ins (ins);
 900
 901         /* FIXME: Support longs/floats */
 902         /* FIXME: Work on vregs as well */
 903
 904         if (MONO_IS_PHI (ins)) {
 905                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 906                 MonoInst *c0 = NULL;
 907                 int j;
 908
 909                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 910                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 911                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 912                         MonoInst *src = mv->def;
 913
 914                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 915                                 continue;
 916
 917                         if (!mv->def || !src || mv->cpstate == 2) {
 918                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 919                                 break;
 920                         }
 921
 922                         if (mv->cpstate == 0)
 923                                 continue;
 924
 925                         g_assert (carray [var->dreg]);
 926
 927                         if (!c0)
 928                                 c0 = carray [var->dreg];
 929
 930                         /* FIXME: */
 931                         if (c0->opcode != OP_ICONST) {
 932                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 933                                 break;
 934                         }
 935
 936                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 937                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 938                                 break;
 939                         }
 940                 }
 941
 942                 if (c0 && info->cpstate < 1) {
 943                         change_varstate (cfg, cvars, info, 1, c0, carray);
 944
 945                         g_assert (c0->opcode == OP_ICONST);
 946                 }
 947         }
 948         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 949                 MonoInst *var, *c0;
 950                 int state;
 951
 952                 if (spec [MONO_INST_DEST] !=  ' ')
 953                         var = get_vreg_to_inst (cfg, ins->dreg);
 954                 else
 955                         var = NULL;
 956
 957                 c0 = NULL;
 958                 state = evaluate_ins (cfg, ins, &c0, carray);
 959
 960                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 961                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 962
 963                         if (info->cpstate < 2) {
 964                                 if (state == 1)
 965                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 966                                 else if (state == 2)
 967                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 968                         }
 969                 }
 970                 else if (!var && (ins->dreg != -1)) {
 971                         /*
 972                          * We don't record def-use information for local vregs since it would be
 973                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 974                          * the same bblock, so they will be examined after the definition.
 975                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 976                          */
 977                         if (c0) {
 978                                 carray [ins->dreg] = c0;
 979                         } else {
 980                                 if (carray [ins->dreg]) {
 981                                         /*
 982                                          * The state of the vreg changed from constant to non-constant
 983                                          * -> need to rescan the whole bblock.
 984                                          */
 985                                         carray [ins->dreg] = NULL;
 986                                         /* FIXME: Speed this up */
 987
 988                                         if (!g_list_find (*bblist, bb))
 989                                                 *bblist = g_list_prepend (*bblist, bb);
 990                                 }
 991                         }
 992                 }
 993
 994                 if (ins->opcode == OP_JUMP_TABLE) {
 995                         int i;
 996                         MonoJumpInfoBBTable *table = ins->inst_p0;
 997
 998                         if (ins->next->opcode != OP_PADD) {
 999                                 /* The PADD was optimized away */
1000                                 /* FIXME: handle this as well */
1001                                 for (i = 0; i < table->table_size; i++)
1002                                         if (table->table [i])
1003                                                 add_cprop_bb (cfg, table->table [i], bblist);
1004                                 return;
1005                         }
1006
1007                         g_assert (ins->next->opcode == OP_PADD);
1008                         g_assert (ins->next->sreg1 == ins->dreg);
1009
1010                         if (carray [ins->next->sreg2]) {
1011 #if SIZEOF_VOID_P == 8
1012                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1013 #else
1014                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1015 #endif
1016                                 if ((idx < 0) || (idx >= table->table_size))
1017                                         /* Out-of-range, no branch is executed */
1018                                         return;
1019                                 else
1020                                         if (table->table [idx])
1021                                                 add_cprop_bb (cfg, table->table [idx], bblist);
1022                         }
1023                         else {
1024                                 for (i = 0; i < table->table_size; i++)
1025                                         if (table->table [i])
1026                                                 add_cprop_bb (cfg, table->table [i], bblist);
1027                         }
1028                 }
1029
1030                 if (ins->opcode == OP_SWITCH) {
1031                         int i;
1032                         MonoJumpInfoBBTable *table = ins->inst_p0;
1033
1034                         for (i = 0; i < table->table_size; i++)
1035                                 if (table->table [i])
1036                                         add_cprop_bb (cfg, table->table [i], bblist);
1037                 }
1038
1039                 /* Handle COMPARE+BRCOND pairs */
1040                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
1041                         if (c0) {
1042                                 g_assert (c0->opcode == OP_ICONST);
1043
1044                                 if (c0->inst_c0)
1045                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
1046                                 else
1047                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
1048                         }
1049                         else {
1050                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1051                         }
1052
1053                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1054                 }
1055         } else if (ins->opcode == OP_BR) {
1056                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1057         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1058                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1059                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1060                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1061                         if (ins->inst_false_bb)
1062                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1063         } else {
1064                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1065                         if (ins->inst_false_bb)
1066                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1067                 }
1068         }
1069 }
1070
1071 /**
1072  * fold_ins:
1073  *
1074  *   Replace INS with its constant value, if it exists
1075  */
1076 static void
1077 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1078 {
1079         const char *spec = INS_INFO (ins->opcode);
1080         int opcode2;
1081
1082         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1083                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1084                         /* Perform constant folding */
1085                         /* FIXME: */
1086                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1087                         ins->opcode = OP_ICONST;
1088                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1089                         ins->sreg1 = ins->sreg2 = -1;
1090                 }
1091                 else if ((spec [MONO_INST_SRC2] != ' ') && carray [ins->sreg2]) {
1092                         /* Perform op->op_imm conversion */
1093                         opcode2 = mono_op_to_op_imm (ins->opcode);
1094                         if (opcode2 != -1) {
1095                                 ins->opcode = opcode2;
1096                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1097                                 ins->sreg2 = -1;
1098
1099                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1100                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1101                         }
1102                 }
1103
1104                 if (ins->opcode == OP_JUMP_TABLE) {
1105                         int i;
1106                         MonoJumpInfoBBTable *table = ins->inst_p0;
1107
1108                         if (ins->next->opcode != OP_PADD) {
1109                                 /* The PADD was optimized away */
1110                                 /* FIXME: handle this as well */
1111                                 return;
1112                         }
1113
1114                         g_assert (ins->next->opcode == OP_PADD);
1115                         g_assert (ins->next->sreg1 == ins->dreg);
1116                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1117
1118                         if (carray [ins->next->sreg2]) {
1119                                 /* Convert to a simple branch */
1120 #if SIZEOF_VOID_P == 8
1121                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1122 #else
1123                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1124 #endif
1125
1126                                 if (!((idx >= 0) && (idx < table->table_size))) {
1127                                         /* Out of range, eliminate the whole switch */
1128                                         for (i = 0; i < table->table_size; ++i) {
1129                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1130                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1131                                         }
1132
1133                                         NULLIFY_INS (ins);
1134                                         NULLIFY_INS (ins->next);
1135                                         NULLIFY_INS (ins->next->next);
1136                                         NULLIFY_INS (ins->next->next->next);
1137
1138                                         return;
1139                                 }
1140
1141                                 if (ins->next->next->next->opcode != OP_BR_REG) {
1142                                         /* A one-way switch which got optimized away */
1143                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1144                                                 printf ("\tNo cfold on ");
1145                                                 mono_print_ins (ins);
1146                                         }
1147                                         return;
1148                                 }
1149
1150                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1151                                         printf ("\tcfold on ");
1152                                         mono_print_ins (ins);
1153                                 }
1154
1155                                 /* Unlink target bblocks */
1156                                 for (i = 0; i < table->table_size; ++i) {
1157                                         if (i != idx) {
1158                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1159                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1160                                         }
1161                                 }
1162
1163                                 /* Change the OP_BR_REG to a simple branch */
1164                                 ins->next->next->next->opcode = OP_BR;
1165                                 ins->next->next->next->inst_target_bb = table->table [idx];
1166                                 ins->next->next->next->sreg1 = -1;
1167
1168                                 /* Nullify the other instructions */
1169                                 NULLIFY_INS (ins);
1170                                 NULLIFY_INS (ins->next);
1171                                 NULLIFY_INS (ins->next->next);
1172                         }
1173                 }
1174         }
1175         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1176                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1177                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1178                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1179                         ins->opcode = OP_BR;
1180                         ins->inst_target_bb = ins->inst_true_bb;
1181                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1182                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1183                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1184                         ins->opcode = OP_BR;
1185                         ins->inst_target_bb = ins->inst_false_bb;
1186                 }
1187         }
1188 }
1189
1190 void
1191 mono_ssa_cprop2 (MonoCompile *cfg)
1192 {
1193         MonoInst **carray;
1194         MonoBasicBlock *bb;
1195         GList *bblock_list, *cvars;
1196         GList *tmp;
1197         int i;
1198         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1199
1200         carray = g_new0 (MonoInst*, cfg->next_vreg);
1201
1202         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1203                 mono_ssa_create_def_use (cfg);
1204
1205         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1206         cfg->bb_entry->flags |= BB_REACHABLE;
1207
1208         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1209
1210         for (i = 0; i < cfg->num_varinfo; i++) {
1211                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1212                 if (!info->def)
1213                         info->cpstate = 2;
1214         }
1215
1216         cvars = NULL;
1217
1218         while (bblock_list) {
1219                 MonoInst *inst;
1220
1221                 bb = (MonoBasicBlock *)bblock_list->data;
1222
1223                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1224
1225                 g_assert (bb->flags &  BB_REACHABLE);
1226
1227                 if (bb->out_count == 1) {
1228                         if (!(bb->out_bb [0]->flags &  BB_REACHABLE)) {
1229                                 bb->out_bb [0]->flags |= BB_REACHABLE;
1230                                 bblock_list = g_list_prepend (bblock_list, bb->out_bb [0]);
1231                         }
1232                 }
1233
1234                 if (cfg->verbose_level > 1)
1235                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1236
1237                 for (inst = bb->code; inst; inst = inst->next) {
1238                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1239                 }
1240
1241                 while (cvars) {
1242                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1243                         cvars = g_list_delete_link (cvars, cvars);
1244
1245                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1246                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1247                                 if (!(ui->bb->flags & BB_REACHABLE))
1248                                         continue;
1249                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1250                         }
1251                 }
1252         }
1253
1254         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1255                 MonoInst *inst;
1256                 for (inst = bb->code; inst; inst = inst->next) {
1257                         fold_ins (cfg, bb, inst, carray);
1258                 }
1259         }
1260
1261         g_free (carray);
1262
1263         cfg->comp_done |= MONO_COMP_REACHABILITY;
1264
1265         /* fixme: we should update usage infos during cprop, instead of computing it again */
1266         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1267         for (i = 0; i < cfg->num_varinfo; i++) {
1268                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1269                 info->def = NULL;
1270                 info->uses = NULL;
1271         }
1272 }
1273
1274 static inline void
1275 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1276 {
1277         GList *tmp;
1278
1279         *wl = g_list_prepend_mempool (*wl, cfg->mempool, use);
1280
1281         for (tmp = use->uses; tmp; tmp = tmp->next) {
1282                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1283                 if (ui->inst == var->def) {
1284                         /* from the mempool */
1285                         use->uses = g_list_remove_link (use->uses, tmp);
1286                         break;
1287                 }
1288         }
1289 }
1290
1291 void
1292 mono_ssa_deadce2 (MonoCompile *cfg)
1293 {
1294         int i;
1295         GList *work_list;
1296
1297         g_assert (cfg->comp_done & MONO_COMP_SSA);
1298
1299         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1300
1301         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1302                 mono_ssa_create_def_use (cfg);
1303
1304         mono_ssa_copyprop (cfg);
1305
1306         work_list = NULL;
1307         for (i = 0; i < cfg->num_varinfo; i++) {
1308                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1309                 work_list = g_list_prepend_mempool (work_list, cfg->mempool, info);
1310         }
1311
1312         while (work_list) {
1313                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1314                 work_list = g_list_remove_link (work_list, work_list);
1315
1316                 /*
1317                  * The second part of the condition happens often when PHI nodes have their dreg
1318                  * as one of their arguments due to the fact that we use the original vars.
1319                  */
1320                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1321                         MonoInst *def = info->def;
1322
1323                         /* Eliminating FMOVE could screw up the fp stack */
1324                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1325                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1326                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1327                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1328                                 def->opcode = OP_NOP;
1329                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1330                                 info->reg = -1;
1331                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || (def->opcode == OP_VZERO)) {
1332                                 def->opcode = OP_NOP;
1333                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1334                                 info->reg = -1;
1335                         } else if (MONO_IS_PHI (def)) {
1336                                 int j;
1337                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1338                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1339                                         add_to_dce_worklist (cfg, info, u, &work_list);
1340                                 }
1341                                 def->opcode = OP_NOP;
1342                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1343                                 info->reg = -1;
1344                         }
1345                         else if (def->opcode == OP_NOP) {
1346                         }
1347                         //else
1348                         //mono_print_ins (def);
1349                 }
1350
1351         }
1352 }
1353
1354 #if 0
1355 void
1356 mono_ssa_strength_reduction (MonoCompile *cfg)
1357 {
1358         MonoBasicBlock *bb;
1359         int i;
1360
1361         g_assert (cfg->comp_done & MONO_COMP_SSA);
1362         g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1363         g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1364
1365         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1366                 GList *lp = bb->loop_blocks;
1367
1368                 if (lp) {
1369                         MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1370
1371                         /* we only consider loops with 2 in bblocks */
1372                         if (!h->in_count == 2)
1373                                 continue;
1374
1375                         for (i = 0; i < cfg->num_varinfo; i++) {
1376                                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1377
1378                                 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1379                                     info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1380                                         MonoInst *v = info->def->inst_i1;
1381
1382
1383                                         printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1384                                 }
1385                         }
1386                 }
1387         }
1388 }
1389 #endif