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