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                 if (cfg->varinfo [i]->opcode == OP_ARG)
 374                         mono_bitset_set_fast (vinfo [i].def_in, 0);
 375         }
 376
 377         for (i = 0; i < cfg->num_bblocks; ++i) {
 378                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 379                         if (ins->opcode == OP_NOP)
 380                                 continue;
 381
 382                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 383                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 384                         }
 385                 }
 386         }
 387
 388         /* insert phi functions */
 389         for (i = 0; i < cfg->num_varinfo; ++i) {
 390                 MonoInst *var = cfg->varinfo [i];
 391
 392 #if SIZEOF_VOID_P == 4
 393                 if (var->type == STACK_I8)
 394                         continue;
 395 #endif
 396                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 397                         continue;
 398
 399                 /* Most variables have only one definition */
 400                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 401                         continue;
 402
 403                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 404
 405                 if (cfg->verbose_level >= 4) {
 406                         if (mono_bitset_count (set) > 0) {
 407                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 408                                 mono_blockset_print (cfg, set, "", -1);
 409                         }
 410                 }
 411
 412                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 413                         MonoBasicBlock *bb = cfg->bblocks [idx];
 414
 415                         /* fixme: create pruned SSA? we would need liveness information for that */
 416
 417                         if (bb == cfg->bb_exit)
 418                                 continue;
 419
 420                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 421                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 422                                 continue;
 423                         }
 424
 425                         NEW_PHI (cfg, ins, i);
 426
 427                         switch (var->type) {
 428                         case STACK_I4:
 429                         case STACK_I8:
 430                         case STACK_PTR:
 431                         case STACK_MP:
 432                         case STACK_OBJ:
 433                                 ins->opcode = OP_PHI;
 434                                 break;
 435                         case STACK_R8:
 436                                 ins->opcode = OP_FPHI;
 437                                 break;
 438                         case STACK_VTYPE:
 439                                 ins->opcode = OP_VPHI;
 440                                 ins->klass = var->klass;
 441                                 break;
 442                         }
 443
 444                         ins->inst_phi_args =  mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 445                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 446
 447                         /* For debugging */
 448                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 449                                 ins->inst_phi_args [j + 1] = -1;
 450
 451                         ins->dreg = cfg->varinfo [i]->dreg;
 452
 453                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 454
 455 #ifdef DEBUG_SSA
 456                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 457 #endif
 458                 }
 459         }
 460
 461         /* free the stuff */
 462         g_free (vinfo);
 463         g_free (buf_start);
 464
 465         /* Renaming phase */
 466
 467         stack = alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 468         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 469
 470         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 471         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 472         stack_history_size = 10240;
 473         stack_history = g_new (RenameInfo, stack_history_size);
 474         originals = g_new0 (gboolean, cfg->num_varinfo);
 475         mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 476         g_free (stack_history);
 477         g_free (originals);
 478
 479         if (cfg->verbose_level >= 4)
 480                 printf ("\nEND COMPUTE SSA.\n\n");
 481
 482         cfg->comp_done |= MONO_COMP_SSA;
 483 }
 484
 485 void
 486 mono_ssa_remove (MonoCompile *cfg)
 487 {
 488         MonoInst *ins, *var, *move;
 489         int i, j, first;
 490
 491         g_assert (cfg->comp_done & MONO_COMP_SSA);
 492
 493         for (i = 0; i < cfg->num_bblocks; ++i) {
 494                 MonoBasicBlock *bb = cfg->bblocks [i];
 495
 496                 if (cfg->verbose_level >= 4)
 497                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 498
 499                 for (ins = bb->code; ins; ins = ins->next) {
 500                         if (MONO_IS_PHI (ins)) {
 501                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 502                                 var = get_vreg_to_inst (cfg, ins->dreg);
 503
 504                                 /* Check for PHI nodes where all the inputs are the same */
 505                                 first = ins->inst_phi_args [1];
 506
 507                                 for (j = 1; j < bb->in_count; ++j)
 508                                         if (first != ins->inst_phi_args [j + 1])
 509                                                 break;
 510
 511                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 512                                         ins->opcode = op_phi_to_move (ins->opcode);
 513                                         if (ins->opcode == OP_VMOVE)
 514                                                 g_assert (ins->klass);
 515                                         ins->sreg1 = first;
 516                                 } else {
 517                                         for (j = 0; j < bb->in_count; j++) {
 518                                                 MonoBasicBlock *pred = bb->in_bb [j];
 519                                                 int sreg = ins->inst_phi_args [j + 1];
 520
 521                                                 if (cfg->verbose_level >= 4)
 522                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 523                                                 if (var->dreg != sreg) {
 524                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 525                                                         if (move->opcode == OP_VMOVE) {
 526                                                                 g_assert (ins->klass);
 527                                                                 move->klass = ins->klass;
 528                                                         }
 529                                                         move->dreg = var->dreg;
 530                                                         move->sreg1 = sreg;
 531                                                         mono_add_ins_to_end (pred, move);
 532                                                 }
 533                                         }
 534
 535                                         ins->opcode = OP_NOP;
 536                                         ins->dreg = -1;
 537                                 }
 538                         }
 539                 }
 540         }
 541
 542         if (cfg->verbose_level >= 4) {
 543                 for (i = 0; i < cfg->num_bblocks; ++i) {
 544                         MonoBasicBlock *bb = cfg->bblocks [i];
 545
 546                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 547                 }
 548         }
 549
 550         /*
 551          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 552          * the variables if possible. Since the newly introduced SSA variables don't
 553          * have overlapping live ranges (because we don't do agressive optimization), we
 554          * can coalesce them into the original variable.
 555          */
 556
 557         for (i = 0; i < cfg->num_bblocks; ++i) {
 558                 MonoBasicBlock *bb = cfg->bblocks [i];
 559
 560                 for (ins = bb->code; ins; ins = ins->next) {
 561                         const char *spec = INS_INFO (ins->opcode);
 562
 563                         if (ins->opcode == OP_NOP)
 564                                 continue;
 565
 566                         if (spec [MONO_INST_DEST] != ' ') {
 567                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 568
 569                                 if (var) {
 570                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 571
 572                                         /*
 573                                          * The third condition avoids coalescing with variables eliminated
 574                                          * during deadce.
 575                                          */
 576                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 577                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 578                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 579                                         }
 580                                 }
 581                         }
 582
 583                         if (spec [MONO_INST_SRC1] != ' ') {
 584                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg1);
 585
 586                                 if (var) {
 587                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 588
 589                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 590                                                 printf ("COALESCE: R%d -> R%d\n", ins->sreg1, cfg->varinfo [vmv->reg]->dreg);
 591                                                 ins->sreg1 = cfg->varinfo [vmv->reg]->dreg;
 592                                         }
 593                                 }
 594                         }
 595
 596                         if (spec [MONO_INST_SRC2] != ' ') {
 597                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg2);
 598
 599                                 if (var) {
 600                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 601
 602                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 603                                                 printf ("COALESCE: R%d -> R%d\n", ins->sreg2, cfg->varinfo [vmv->reg]->dreg);
 604                                                 ins->sreg2 = cfg->varinfo [vmv->reg]->dreg;
 605                                         }
 606                                 }
 607                         }
 608
 609                 }
 610         }
 611
 612         for (i = 0; i < cfg->num_varinfo; ++i) {
 613                 MONO_VARINFO (cfg, i)->reg = -1;
 614         }
 615
 616         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 617                 unlink_unused_bblocks (cfg);
 618
 619         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 620
 621         cfg->comp_done &= ~MONO_COMP_SSA;
 622 }
 623
 624 static void
 625 mono_ssa_create_def_use (MonoCompile *cfg)
 626 {
 627         MonoBasicBlock *bb;
 628         MonoInst *ins;
 629         int i;
 630
 631         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 632
 633         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 634                 for (ins = bb->code; ins; ins = ins->next) {
 635                         const char *spec = INS_INFO (ins->opcode);
 636                         MonoMethodVar *info;
 637
 638                         if (ins->opcode == OP_NOP)
 639                                 continue;
 640
 641                         /* SREG1 */
 642                         if (spec [MONO_INST_SRC1] != ' ') {
 643                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg1);
 644                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 645                                         record_use (cfg, var, bb, ins);
 646                         }
 647
 648                         /* SREG2 */
 649                         if (spec [MONO_INST_SRC2] != ' ') {
 650                                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg2);
 651                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 652                                         record_use (cfg, var, bb, ins);
 653                         }
 654
 655                         if (MONO_IS_STORE_MEMBASE (ins)) {
 656                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 657                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 658                                         record_use (cfg, var, bb, ins);
 659                         }
 660
 661                         if (MONO_IS_PHI (ins)) {
 662                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 663                                         g_assert (ins->inst_phi_args [i] != -1);
 664                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 665                                 }
 666                         }
 667
 668                         /* DREG */
 669                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 670                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 671
 672                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 673                                         info = MONO_VARINFO (cfg, var->inst_c0);
 674                                         info->def = ins;
 675                                         info->def_bb = bb;
 676                                 }
 677                         }
 678                 }
 679         }
 680
 681         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 682 }
 683
 684 static void
 685 mono_ssa_copyprop (MonoCompile *cfg)
 686 {
 687         int i, index;
 688         GList *l;
 689
 690         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 691
 692         for (index = 0; index < cfg->num_varinfo; ++index) {
 693                 MonoInst *var = cfg->varinfo [index];
 694                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 695
 696                 if (info->def && (MONO_IS_MOVE (info->def))) {
 697                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 698
 699                         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))) {
 700                                 /* Rewrite all uses of var to be uses of var2 */
 701                                 int dreg = var->dreg;
 702                                 int sreg1 = var2->dreg;
 703                                 const char *spec;
 704
 705                                 l = info->uses;
 706                                 while (l) {
 707                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 708                                         MonoInst *ins = u->inst;
 709                                         GList *next = l->next;
 710
 711                                         spec = INS_INFO (ins->opcode);
 712
 713                                         if (spec [MONO_INST_SRC1] != ' ' && ins->sreg1 == dreg) {
 714                                                 ins->sreg1 = sreg1;
 715                                         } else if (spec [MONO_INST_SRC2] != ' ' && ins->sreg2 == dreg) {
 716                                                 ins->sreg2 = sreg1;
 717                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 718                                                 ins->dreg = sreg1;
 719                                         } else if (MONO_IS_PHI (ins)) {
 720                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 721                                                         int sreg = ins->inst_phi_args [i];
 722                                                         if (sreg == var->dreg)
 723                                                                 break;
 724                                                 }
 725                                                 g_assert (i > 0);
 726                                                 ins->inst_phi_args [i] = sreg1;
 727                                         }
 728                                         else
 729                                                 g_assert_not_reached ();
 730
 731                                         record_use (cfg, var2, u->bb, ins);
 732
 733                                         l = next;
 734                                 }
 735
 736                                 info->uses = NULL;
 737                         }
 738                 }
 739         }
 740
 741         if (cfg->verbose_level >= 4) {
 742                 MonoBasicBlock *bb;
 743
 744                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 745                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 746         }
 747 }
 748
 749 static int
 750 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 751 {
 752         MonoInst *arg0, *arg1, *c0;
 753         int r1, r2;
 754         gboolean const_args = FALSE;
 755         const char *spec = INS_INFO (ins->opcode);
 756
 757         /* Short-circuit this */
 758         if (ins->opcode == OP_ICONST) {
 759                 *res = ins;
 760                 return 1;
 761         }
 762
 763         if (ins->opcode == OP_NOP)
 764                 return 2;
 765
 766         arg0 = NULL;
 767         if (spec [MONO_INST_SRC1] != ' ') {
 768                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg1);
 769
 770                 r1 = 2;
 771                 arg0 = carray [ins->sreg1];
 772                 if (arg0)
 773                         r1 = 1;
 774                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 775                         r1 = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 776         } else {
 777                 r1 = 2;
 778         }
 779
 780         arg1 = NULL;
 781         if (spec [MONO_INST_SRC2] != ' ') {
 782                 MonoInst *var = get_vreg_to_inst (cfg, ins->sreg2);
 783
 784                 r2 = 2;
 785                 arg1 = carray [ins->sreg2];
 786                 if (arg1)
 787                         r2 = 1;
 788                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 789                         r2 = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 790         }
 791         else {
 792                 r2 = 0;
 793         }
 794
 795         c0 = NULL;
 796         if ((spec [MONO_INST_SRC1] != ' ') && (spec [MONO_INST_SRC2] != ' ')) {
 797                 /* Binop */
 798                 const_args = (r1 == 1) && (r2 == 1);
 799         }
 800         else if (spec [MONO_INST_SRC1] != ' ') {
 801                 /* Unop */
 802                 const_args = (r1 == 1);
 803         }
 804
 805         if (const_args) {
 806                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 807                         // Cached value
 808                         *res = carray [ins->dreg];
 809                         return 1;
 810                 }
 811                 c0 = mono_constant_fold_ins (cfg, ins, arg0, arg1, FALSE);
 812                 if (c0) {
 813                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 814                                 printf ("\t cfold -> ");
 815                                 mono_print_ins (c0);
 816                         }
 817                         *res = c0;
 818                         return 1;
 819                 }
 820                 else
 821                         /* Can't cfold this ins */
 822                         return 2;
 823         }
 824
 825         if ((spec [MONO_INST_SRC1] != ' ') && (spec [MONO_INST_SRC2] != ' ')) {
 826                 /* Binop */
 827                 if ((r1 == 2) || (r2 == 2))
 828                         return 2;
 829                 else
 830                         return 0;
 831         }
 832         else if (spec [MONO_INST_SRC1] != ' ') {
 833                 /* Unop */
 834                 if (r1 == 2)
 835                         return 2;
 836                 else
 837                         return 0;
 838         }
 839         else
 840                 return 2;
 841 }
 842
 843 static inline void
 844 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 845 {
 846         if (info->cpstate >= state)
 847                 return;
 848
 849         info->cpstate = state;
 850
 851         if (G_UNLIKELY (cfg->verbose_level > 1))
 852                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 853
 854         if (state == 1)
 855                 g_assert (c0);
 856
 857         carray [cfg->varinfo [info->idx]->dreg] = c0;
 858
 859         if (!g_list_find (*cvars, info)) {
 860                 *cvars = g_list_prepend (*cvars, info);
 861         }
 862 }
 863
 864 static inline void
 865 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 866 {
 867         if (G_UNLIKELY (cfg->verbose_level > 1))
 868                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 869
 870     if (!(bb->flags &  BB_REACHABLE)) {
 871             bb->flags |= BB_REACHABLE;
 872                 *bblist = g_list_prepend (*bblist, bb);
 873         }
 874 }
 875
 876 static void
 877 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 878 {
 879         const char *spec = INS_INFO (ins->opcode);
 880
 881         if (ins->opcode == OP_NOP)
 882                 return;
 883
 884         if (cfg->verbose_level > 1)
 885                 mono_print_ins (ins);
 886
 887         /* FIXME: Support longs/floats */
 888         /* FIXME: Work on vregs as well */
 889
 890         if (MONO_IS_PHI (ins)) {
 891                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 892                 MonoInst *c0 = NULL;
 893                 int j;
 894
 895                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 896                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 897                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 898                         MonoInst *src = mv->def;
 899
 900                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 901                                 continue;
 902
 903                         if (!mv->def || !src || mv->cpstate == 2) {
 904                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 905                                 break;
 906                         }
 907
 908                         if (mv->cpstate == 0)
 909                                 continue;
 910
 911                         g_assert (carray [var->dreg]);
 912
 913                         if (!c0)
 914                                 c0 = carray [var->dreg];
 915
 916                         /* FIXME: */
 917                         if (c0->opcode != OP_ICONST) {
 918                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 919                                 break;
 920                         }
 921
 922                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 923                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 924                                 break;
 925                         }
 926                 }
 927
 928                 if (c0 && info->cpstate < 1) {
 929                         change_varstate (cfg, cvars, info, 1, c0, carray);
 930
 931                         g_assert (c0->opcode == OP_ICONST);
 932                 }
 933         }
 934         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 935                 MonoInst *var, *c0;
 936                 int state;
 937
 938                 if (spec [MONO_INST_DEST] !=  ' ')
 939                         var = get_vreg_to_inst (cfg, ins->dreg);
 940                 else
 941                         var = NULL;
 942
 943                 c0 = NULL;
 944                 state = evaluate_ins (cfg, ins, &c0, carray);
 945
 946                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 947                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 948
 949                         if (info->cpstate < 2) {
 950                                 if (state == 1)
 951                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 952                                 else if (state == 2)
 953                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 954                         }
 955                 }
 956                 else if (!var && (ins->dreg != -1)) {
 957                         /*
 958                          * We don't record def-use information for local vregs since it would be
 959                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 960                          * the same bblock, so they will be examined after the definition.
 961                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 962                          */
 963                         if (c0) {
 964                                 carray [ins->dreg] = c0;
 965                         } else {
 966                                 if (carray [ins->dreg]) {
 967                                         /*
 968                                          * The state of the vreg changed from constant to non-constant
 969                                          * -> need to rescan the whole bblock.
 970                                          */
 971                                         carray [ins->dreg] = NULL;
 972                                         /* FIXME: Speed this up */
 973
 974                                         if (!g_list_find (*bblist, bb))
 975                                                 *bblist = g_list_prepend (*bblist, bb);
 976                                 }
 977                         }
 978                 }
 979
 980                 if (ins->opcode == OP_JUMP_TABLE) {
 981                         int i;
 982                         MonoJumpInfoBBTable *table = ins->inst_p0;
 983
 984                         if (ins->next->opcode != OP_PADD) {
 985                                 /* The PADD was optimized away */
 986                                 /* FIXME: handle this as well */
 987                                 for (i = 0; i < table->table_size; i++)
 988                                         if (table->table [i])
 989                                                 add_cprop_bb (cfg, table->table [i], bblist);
 990                                 return;
 991                         }
 992
 993                         g_assert (ins->next->opcode == OP_PADD);
 994                         g_assert (ins->next->sreg1 == ins->dreg);
 995
 996                         if (carray [ins->next->sreg2]) {
 997 #if SIZEOF_VOID_P == 8
 998                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
 999 #else
1000                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1001 #endif
1002                                 if ((idx < 0) || (idx >= table->table_size))
1003                                         /* Out-of-range, no branch is executed */
1004                                         return;
1005                                 else
1006                                         if (table->table [idx])
1007                                                 add_cprop_bb (cfg, table->table [idx], bblist);
1008                         }
1009                         else {
1010                                 for (i = 0; i < table->table_size; i++)
1011                                         if (table->table [i])
1012                                                 add_cprop_bb (cfg, table->table [i], bblist);
1013                         }
1014                 }
1015
1016                 if (ins->opcode == OP_SWITCH) {
1017                         int i;
1018                         MonoJumpInfoBBTable *table = ins->inst_p0;
1019
1020                         for (i = 0; i < table->table_size; i++)
1021                                 if (table->table [i])
1022                                         add_cprop_bb (cfg, table->table [i], bblist);
1023                 }
1024
1025                 /* Handle COMPARE+BRCOND pairs */
1026                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
1027                         if (c0) {
1028                                 g_assert (c0->opcode == OP_ICONST);
1029
1030                                 if (c0->inst_c0)
1031                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
1032                                 else
1033                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
1034                         }
1035                         else {
1036                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1037                         }
1038
1039                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1040                 }
1041         } else if (ins->opcode == OP_BR) {
1042                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1043         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1044                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1045                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1046                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1047                         if (ins->inst_false_bb)
1048                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1049         } else {
1050                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1051                         if (ins->inst_false_bb)
1052                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1053                 }
1054         }
1055 }
1056
1057 /**
1058  * fold_ins:
1059  *
1060  *   Replace INS with its constant value, if it exists
1061  */
1062 static void
1063 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1064 {
1065         const char *spec = INS_INFO (ins->opcode);
1066         int opcode2;
1067
1068         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1069                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1070                         /* Perform constant folding */
1071                         /* FIXME: */
1072                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1073                         ins->opcode = OP_ICONST;
1074                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1075                         ins->sreg1 = ins->sreg2 = -1;
1076                 }
1077                 else if ((spec [MONO_INST_SRC2] != ' ') && carray [ins->sreg2]) {
1078                         /* Perform op->op_imm conversion */
1079                         opcode2 = mono_op_to_op_imm (ins->opcode);
1080                         if (opcode2 != -1) {
1081                                 ins->opcode = opcode2;
1082                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1083                                 ins->sreg2 = -1;
1084
1085                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1086                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1087                         }
1088                 }
1089
1090                 if (ins->opcode == OP_JUMP_TABLE) {
1091                         int i;
1092                         MonoJumpInfoBBTable *table = ins->inst_p0;
1093
1094                         if (ins->next->opcode != OP_PADD) {
1095                                 /* The PADD was optimized away */
1096                                 /* FIXME: handle this as well */
1097                                 return;
1098                         }
1099
1100                         g_assert (ins->next->opcode == OP_PADD);
1101                         g_assert (ins->next->sreg1 == ins->dreg);
1102                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1103
1104                         if (carray [ins->next->sreg2]) {
1105                                 /* Convert to a simple branch */
1106 #if SIZEOF_VOID_P == 8
1107                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1108 #else
1109                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1110 #endif
1111
1112                                 if (!((idx >= 0) && (idx < table->table_size))) {
1113                                         /* Out of range, eliminate the whole switch */
1114                                         for (i = 0; i < table->table_size; ++i) {
1115                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1116                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1117                                         }
1118
1119                                         NULLIFY_INS (ins);
1120                                         NULLIFY_INS (ins->next);
1121                                         NULLIFY_INS (ins->next->next);
1122                                         NULLIFY_INS (ins->next->next->next);
1123
1124                                         return;
1125                                 }
1126
1127                                 if (ins->next->next->next->opcode != OP_BR_REG) {
1128                                         /* A one-way switch which got optimized away */
1129                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1130                                                 printf ("\tNo cfold on ");
1131                                                 mono_print_ins (ins);
1132                                         }
1133                                         return;
1134                                 }
1135
1136                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1137                                         printf ("\tcfold on ");
1138                                         mono_print_ins (ins);
1139                                 }
1140
1141                                 /* Unlink target bblocks */
1142                                 for (i = 0; i < table->table_size; ++i) {
1143                                         if (i != idx) {
1144                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1145                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1146                                         }
1147                                 }
1148
1149                                 /* Change the OP_BR_REG to a simple branch */
1150                                 ins->next->next->next->opcode = OP_BR;
1151                                 ins->next->next->next->inst_target_bb = table->table [idx];
1152                                 ins->next->next->next->sreg1 = -1;
1153
1154                                 /* Nullify the other instructions */
1155                                 NULLIFY_INS (ins);
1156                                 NULLIFY_INS (ins->next);
1157                                 NULLIFY_INS (ins->next->next);
1158                         }
1159                 }
1160         }
1161         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1162                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1163                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1164                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1165                         ins->opcode = OP_BR;
1166                         ins->inst_target_bb = ins->inst_true_bb;
1167                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1168                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1169                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1170                         ins->opcode = OP_BR;
1171                         ins->inst_target_bb = ins->inst_false_bb;
1172                 }
1173         }
1174 }
1175
1176 void
1177 mono_ssa_cprop (MonoCompile *cfg)
1178 {
1179         MonoInst **carray;
1180         MonoBasicBlock *bb;
1181         GList *bblock_list, *cvars;
1182         GList *tmp;
1183         int i;
1184         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1185
1186         carray = g_new0 (MonoInst*, cfg->next_vreg);
1187
1188         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1189                 mono_ssa_create_def_use (cfg);
1190
1191         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1192         cfg->bb_entry->flags |= BB_REACHABLE;
1193
1194         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1195
1196         for (i = 0; i < cfg->num_varinfo; i++) {
1197                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1198                 if (!info->def)
1199                         info->cpstate = 2;
1200         }
1201
1202         cvars = NULL;
1203
1204         while (bblock_list) {
1205                 MonoInst *inst;
1206
1207                 bb = (MonoBasicBlock *)bblock_list->data;
1208
1209                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1210
1211                 g_assert (bb->flags &  BB_REACHABLE);
1212
1213                 if (bb->out_count == 1) {
1214                         if (!(bb->out_bb [0]->flags &  BB_REACHABLE)) {
1215                                 bb->out_bb [0]->flags |= BB_REACHABLE;
1216                                 bblock_list = g_list_prepend (bblock_list, bb->out_bb [0]);
1217                         }
1218                 }
1219
1220                 if (cfg->verbose_level > 1)
1221                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1222
1223                 for (inst = bb->code; inst; inst = inst->next) {
1224                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1225                 }
1226
1227                 while (cvars) {
1228                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1229                         cvars = g_list_delete_link (cvars, cvars);
1230
1231                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1232                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1233                                 if (!(ui->bb->flags & BB_REACHABLE))
1234                                         continue;
1235                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1236                         }
1237                 }
1238         }
1239
1240         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1241                 MonoInst *inst;
1242                 for (inst = bb->code; inst; inst = inst->next) {
1243                         fold_ins (cfg, bb, inst, carray);
1244                 }
1245         }
1246
1247         g_free (carray);
1248
1249         cfg->comp_done |= MONO_COMP_REACHABILITY;
1250
1251         /* fixme: we should update usage infos during cprop, instead of computing it again */
1252         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1253         for (i = 0; i < cfg->num_varinfo; i++) {
1254                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1255                 info->def = NULL;
1256                 info->uses = NULL;
1257         }
1258 }
1259
1260 static inline void
1261 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1262 {
1263         GList *tmp;
1264
1265         *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1266
1267         for (tmp = use->uses; tmp; tmp = tmp->next) {
1268                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1269                 if (ui->inst == var->def) {
1270                         /* from the mempool */
1271                         use->uses = g_list_remove_link (use->uses, tmp);
1272                         break;
1273                 }
1274         }
1275 }
1276
1277 void
1278 mono_ssa_deadce (MonoCompile *cfg)
1279 {
1280         int i;
1281         GList *work_list;
1282
1283         g_assert (cfg->comp_done & MONO_COMP_SSA);
1284
1285         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1286
1287         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1288                 mono_ssa_create_def_use (cfg);
1289
1290         mono_ssa_copyprop (cfg);
1291
1292         work_list = NULL;
1293         for (i = 0; i < cfg->num_varinfo; i++) {
1294                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1295                 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1296         }
1297
1298         while (work_list) {
1299                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1300                 work_list = g_list_remove_link (work_list, work_list);
1301
1302                 /*
1303                  * The second part of the condition happens often when PHI nodes have their dreg
1304                  * as one of their arguments due to the fact that we use the original vars.
1305                  */
1306                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1307                         MonoInst *def = info->def;
1308
1309                         /* Eliminating FMOVE could screw up the fp stack */
1310                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1311                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1312                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1313                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1314                                 def->opcode = OP_NOP;
1315                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1316                                 info->reg = -1;
1317                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1318                                 def->opcode = OP_NOP;
1319                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1320                                 info->reg = -1;
1321                         } else if (MONO_IS_PHI (def)) {
1322                                 int j;
1323                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1324                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1325                                         add_to_dce_worklist (cfg, info, u, &work_list);
1326                                 }
1327                                 def->opcode = OP_NOP;
1328                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1329                                 info->reg = -1;
1330                         }
1331                         else if (def->opcode == OP_NOP) {
1332                         }
1333                         //else
1334                         //mono_print_ins (def);
1335                 }
1336
1337         }
1338 }
1339
1340 #if 0
1341 void
1342 mono_ssa_strength_reduction (MonoCompile *cfg)
1343 {
1344         MonoBasicBlock *bb;
1345         int i;
1346
1347         g_assert (cfg->comp_done & MONO_COMP_SSA);
1348         g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1349         g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1350
1351         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1352                 GList *lp = bb->loop_blocks;
1353
1354                 if (lp) {
1355                         MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1356
1357                         /* we only consider loops with 2 in bblocks */
1358                         if (!h->in_count == 2)
1359                                 continue;
1360
1361                         for (i = 0; i < cfg->num_varinfo; i++) {
1362                                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1363
1364                                 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1365                                     info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1366                                         MonoInst *v = info->def->inst_i1;
1367
1368
1369                                         printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1370                                 }
1371                         }
1372                 }
1373         }
1374 }
1375 #endif
1376
1377 #endif /* DISABLE_JIT */