mono/mini/ssa2.c

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