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