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