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  * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
   9  */
  10 #include <config.h>
  11 #include <string.h>
  12 #include <mono/metadata/debug-helpers.h>
  13 #include <mono/metadata/mempool.h>
  14 #include <mono/metadata/mempool-internals.h>
  15
  16 #ifndef DISABLE_JIT
  17
  18 #include "mini.h"
  19 #ifdef HAVE_ALLOCA_H
  20 #include <alloca.h>
  21 #endif
  22
  23 #define CREATE_PRUNED_SSA
  24
  25 //#define DEBUG_SSA 1
  26
  27 #define NEW_PHI(cfg,dest,val) do {      \
  28         MONO_INST_NEW ((cfg), (dest), OP_PHI); \
  29         (dest)->inst_c0 = (val);                                                           \
  30         } while (0)
  31
  32 typedef struct {
  33         MonoBasicBlock *bb;
  34         MonoInst *inst;
  35 } MonoVarUsageInfo;
  36
  37 static void
  38 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
  39 {
  40         int i;
  41
  42         for (i = 0; i < bb->out_count; i++) {
  43                 if (bb->out_bb [i] == target) {
  44                         bb->out_bb [i] = bb->out_bb [--bb->out_count];
  45                         break;
  46                 }
  47         }
  48         for (i = 0; i < target->in_count; i++) {
  49                 if (target->in_bb [i] == bb) {
  50                         target->in_bb [i] = target->in_bb [--target->in_count];
  51                         break;
  52
  53                 }
  54         }
  55 }
  56
  57 static void
  58 unlink_unused_bblocks (MonoCompile *cfg)
  59 {
  60         int i, j;
  61         MonoBasicBlock *bb;
  62
  63         g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
  64
  65         if (G_UNLIKELY (cfg->verbose_level > 1))
  66                 printf ("\nUNLINK UNUSED BBLOCKS:\n");
  67
  68         for (bb = cfg->bb_entry; bb && bb->next_bb;) {
  69                 if (!(bb->next_bb->flags & BB_REACHABLE)) {
  70                         bb->next_bb = bb->next_bb->next_bb;
  71                 } else
  72                         bb = bb->next_bb;
  73         }
  74
  75         for (i = 1; i < cfg->num_bblocks; i++) {
  76                 bb = cfg->bblocks [i];
  77
  78                 if (!(bb->flags & BB_REACHABLE)) {
  79                         for (j = 0; j < bb->in_count; j++) {
  80                                 unlink_target (bb->in_bb [j], bb);
  81                         }
  82                         for (j = 0; j < bb->out_count; j++) {
  83                                 unlink_target (bb, bb->out_bb [j]);
  84                         }
  85                         if (G_UNLIKELY (cfg->verbose_level > 1))
  86                                 printf ("\tUnlinked BB%d\n", bb->block_num);
  87                 }
  88
  89         }
  90 }
  91
  92 /**
  93  * remove_bb_from_phis:
  94  *
  95  *   Remove BB from the PHI statements in TARGET.
  96  */
  97 static void
  98 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
  99 {
 100         MonoInst *ins;
 101         int i, j;
 102
 103         for (i = 0; i < target->in_count; i++) {
 104                 if (target->in_bb [i] == bb) {
 105                         break;
 106                 }
 107         }
 108         g_assert (i < target->in_count);
 109
 110         for (ins = target->code; ins; ins = ins->next) {
 111                 if (MONO_IS_PHI (ins)) {
 112                         for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
 113                                 ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
 114                         ins->inst_phi_args [0] --;
 115                 }
 116                 else
 117                         break;
 118         }
 119 }
 120
 121 static inline int
 122 op_phi_to_move (int opcode)
 123 {
 124         switch (opcode) {
 125         case OP_PHI:
 126                 return OP_MOVE;
 127         case OP_FPHI:
 128                 return OP_FMOVE;
 129         case OP_VPHI:
 130                 return OP_VMOVE;
 131         case OP_XPHI:
 132                 return OP_XMOVE;
 133         default:
 134                 g_assert_not_reached ();
 135         }
 136
 137         return -1;
 138 }
 139
 140 static inline void
 141 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
 142 {
 143         MonoMethodVar *info;
 144         MonoVarUsageInfo *ui = (MonoVarUsageInfo *)mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
 145
 146         info = MONO_VARINFO (cfg, var->inst_c0);
 147
 148         ui->bb = bb;
 149         ui->inst = ins;
 150         info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
 151 }
 152
 153 typedef struct {
 154         MonoInst *var;
 155         int idx;
 156 } RenameInfo;
 157
 158 /**
 159  * mono_ssa_rename_vars:
 160  *
 161  *  Implement renaming of SSA variables. Also compute def-use information in parallel.
 162  * @stack_history points to an area of memory which can be used for storing changes
 163  * made to the stack, so they can be reverted later.
 164  */
 165 static void
 166 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)
 167 {
 168         MonoInst *ins, *new_var;
 169         int i, j, idx;
 170         GSList *tmp;
 171         int stack_history_len = 0;
 172
 173         if (cfg->verbose_level >= 4)
 174                 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
 175
 176         /* First pass: Create new vars */
 177         for (ins = bb->code; ins; ins = ins->next) {
 178                 const char *spec = INS_INFO (ins->opcode);
 179                 int num_sregs;
 180                 int sregs [MONO_MAX_SRC_REGS];
 181
 182 #ifdef DEBUG_SSA
 183                 printf ("\tProcessing "); mono_print_ins (ins);
 184 #endif
 185                 if (ins->opcode == OP_NOP)
 186                         continue;
 187
 188                 /* SREGs */
 189                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 190                 for (i = 0; i < num_sregs; ++i) {
 191                         if (spec [MONO_INST_SRC1 + i] != ' ') {
 192                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 193                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 194                                         int idx = var->inst_c0;
 195                                         if (stack [idx]) {
 196                                                 if (var->opcode != OP_ARG)
 197                                                         g_assert (stack [idx]);
 198                                                 sregs [i] = stack [idx]->dreg;
 199                                                 record_use (cfg, stack [idx], bb, ins);
 200                                         }
 201                                         else
 202                                                 record_use (cfg, var, bb, ins);
 203                                 }
 204                                 else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
 205                                         sregs [i] = lvreg_stack [sregs [i]];
 206                         }
 207                 }
 208                 mono_inst_set_src_registers (ins, sregs);
 209
 210                 if (MONO_IS_STORE_MEMBASE (ins)) {
 211                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 212                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 213                                 int idx = var->inst_c0;
 214                                 if (stack [idx]) {
 215                                         if (var->opcode != OP_ARG)
 216                                                 g_assert (stack [idx]);
 217                                         ins->dreg = stack [idx]->dreg;
 218                                         record_use (cfg, stack [idx], bb, ins);
 219                                 }
 220                                 else
 221                                         record_use (cfg, var, bb, ins);
 222                         }
 223                         else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
 224                                 ins->dreg = lvreg_stack [ins->dreg];
 225                 }
 226
 227                 /* DREG */
 228                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 229                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 230                         MonoMethodVar *info;
 231
 232                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 233                                 idx = var->inst_c0;
 234                                 g_assert (idx < max_vars);
 235
 236                                 if (var->opcode == OP_ARG)
 237                                         originals_used [idx] = TRUE;
 238
 239                                 /* FIXME: */
 240                                 g_assert (stack_history_len < stack_history_size);
 241                                 stack_history [stack_history_len].var = stack [idx];
 242                                 stack_history [stack_history_len].idx = idx;
 243                                 stack_history_len ++;
 244
 245                                 if (originals_used [idx]) {
 246                                         new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
 247                                         new_var->flags = var->flags;
 248                                         MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
 249
 250                                         if (cfg->verbose_level >= 4)
 251                                                 printf ("  R%d -> R%d\n", var->dreg, new_var->dreg);
 252
 253                                         stack [idx] = new_var;
 254
 255                                         ins->dreg = new_var->dreg;
 256                                         var = new_var;
 257                                 }
 258                                 else {
 259                                         stack [idx] = var;
 260                                         originals_used [idx] = TRUE;
 261                                 }
 262
 263                                 info = MONO_VARINFO (cfg, var->inst_c0);
 264                                 info->def = ins;
 265                                 info->def_bb = bb;
 266                         }
 267                         else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
 268                                 /* Perform renaming for local vregs */
 269                                 lvreg_stack [ins->dreg] = vreg_is_ref (cfg, ins->dreg) ? mono_alloc_ireg_ref (cfg) : mono_alloc_preg (cfg);
 270                                 ins->dreg = lvreg_stack [ins->dreg];
 271                         }
 272                         else
 273                                 lvreg_defined [ins->dreg] = TRUE;
 274                 }
 275
 276 #ifdef DEBUG_SSA
 277                 printf ("\tAfter processing "); mono_print_ins (ins);
 278 #endif
 279
 280         }
 281
 282         /* Rename PHI arguments in succeeding bblocks */
 283         for (i = 0; i < bb->out_count; i++) {
 284                 MonoBasicBlock *n = bb->out_bb [i];
 285
 286                 for (j = 0; j < n->in_count; j++)
 287                         if (n->in_bb [j] == bb)
 288                                 break;
 289
 290                 for (ins = n->code; ins; ins = ins->next) {
 291                         if (MONO_IS_PHI (ins)) {
 292                                 idx = ins->inst_c0;
 293                                 if (stack [idx])
 294                                         new_var = stack [idx];
 295                                 else
 296                                         new_var = cfg->varinfo [idx];
 297 #ifdef DEBUG_SSA
 298                                 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
 299 #endif
 300                                 ins->inst_phi_args [j + 1] = new_var->dreg;
 301                                 record_use (cfg,  new_var, n, ins);
 302                                 if (G_UNLIKELY (cfg->verbose_level >= 4))
 303                                         printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
 304                         }
 305                         else
 306                                 /* The phi nodes are at the beginning of the bblock */
 307                                 break;
 308                 }
 309         }
 310
 311         if (bb->dominated) {
 312                 for (tmp = bb->dominated; tmp; tmp = tmp->next) {
 313                         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);
 314                 }
 315         }
 316
 317         /* Restore stack */
 318         for (i = stack_history_len - 1; i >= 0; i--) {
 319                 stack [stack_history [i].idx] = stack_history [i].var;
 320         }
 321
 322         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 323 }
 324
 325 void
 326 mono_ssa_compute (MonoCompile *cfg)
 327 {
 328         int i, j, idx, bitsize;
 329         MonoBitSet *set;
 330         MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
 331         MonoInst *ins, **stack;
 332         guint8 *buf, *buf_start;
 333         RenameInfo *stack_history;
 334         int stack_history_size;
 335         gboolean *originals;
 336         guint32 *lvreg_stack;
 337         gboolean *lvreg_defined;
 338
 339         g_assert (!(cfg->comp_done & MONO_COMP_SSA));
 340
 341         g_assert (!cfg->disable_ssa);
 342
 343         if (cfg->verbose_level >= 4)
 344                 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
 345
 346 #ifdef CREATE_PRUNED_SSA
 347         /* we need liveness for pruned SSA */
 348         if (!(cfg->comp_done & MONO_COMP_LIVENESS))
 349                 mono_analyze_liveness (cfg);
 350 #endif
 351
 352         mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
 353
 354         bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
 355         buf = buf_start = (guint8 *)g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
 356
 357         for (i = 0; i < cfg->num_varinfo; ++i) {
 358                 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
 359                 buf += bitsize;
 360                 vinfo [i].idx = i;
 361                 /* implicit reference at start */
 362                 if (cfg->varinfo [i]->opcode == OP_ARG)
 363                         mono_bitset_set_fast (vinfo [i].def_in, 0);
 364         }
 365
 366         for (i = 0; i < cfg->num_bblocks; ++i) {
 367                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 368                         if (ins->opcode == OP_NOP)
 369                                 continue;
 370
 371                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 372                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 373                         }
 374                 }
 375         }
 376
 377         /* insert phi functions */
 378         for (i = 0; i < cfg->num_varinfo; ++i) {
 379                 MonoInst *var = cfg->varinfo [i];
 380
 381 #if SIZEOF_REGISTER == 4
 382                 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
 383                         continue;
 384 #endif
 385                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 386                         continue;
 387
 388                 /* Most variables have only one definition */
 389                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 390                         continue;
 391
 392                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 393
 394                 if (cfg->verbose_level >= 4) {
 395                         if (mono_bitset_count (set) > 0) {
 396                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 397                                 mono_blockset_print (cfg, set, "", -1);
 398                         }
 399                 }
 400
 401                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 402                         MonoBasicBlock *bb = cfg->bblocks [idx];
 403
 404                         /* fixme: create pruned SSA? we would need liveness information for that */
 405
 406                         if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
 407                                 continue;
 408
 409                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 410                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 411                                 continue;
 412                         }
 413
 414                         NEW_PHI (cfg, ins, i);
 415
 416                         switch (var->type) {
 417                         case STACK_I4:
 418                         case STACK_I8:
 419                         case STACK_PTR:
 420                         case STACK_MP:
 421                         case STACK_OBJ:
 422                                 ins->opcode = OP_PHI;
 423                                 break;
 424                         case STACK_R8:
 425                                 ins->opcode = OP_FPHI;
 426                                 break;
 427                         case STACK_VTYPE:
 428                                 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
 429                                 break;
 430                         }
 431
 432                         if (var->inst_vtype->byref)
 433                                 ins->klass = mono_defaults.int_class;
 434                         else
 435                                 ins->klass = var->klass;
 436
 437                         ins->inst_phi_args = (int *)mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 438                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 439
 440                         /* For debugging */
 441                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 442                                 ins->inst_phi_args [j + 1] = -1;
 443
 444                         ins->dreg = cfg->varinfo [i]->dreg;
 445
 446                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 447
 448 #ifdef DEBUG_SSA
 449                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 450 #endif
 451                 }
 452         }
 453
 454         /* free the stuff */
 455         g_free (vinfo);
 456         g_free (buf_start);
 457
 458         /* Renaming phase */
 459
 460         stack = (MonoInst **)alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 461         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 462
 463         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 464         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 465         stack_history_size = 10240;
 466         stack_history = g_new (RenameInfo, stack_history_size);
 467         originals = g_new0 (gboolean, cfg->num_varinfo);
 468         mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 469         g_free (stack_history);
 470         g_free (originals);
 471         g_free (lvreg_stack);
 472         g_free (lvreg_defined);
 473
 474         if (cfg->verbose_level >= 4)
 475                 printf ("\nEND COMPUTE SSA.\n\n");
 476
 477         cfg->comp_done |= MONO_COMP_SSA;
 478 }
 479
 480 void
 481 mono_ssa_remove (MonoCompile *cfg)
 482 {
 483         MonoInst *ins, *var, *move;
 484         int bbindex, i, j, first;
 485
 486         g_assert (cfg->comp_done & MONO_COMP_SSA);
 487
 488         for (i = 0; i < cfg->num_bblocks; ++i) {
 489                 MonoBasicBlock *bb = cfg->bblocks [i];
 490
 491                 if (cfg->verbose_level >= 4)
 492                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 493
 494                 for (ins = bb->code; ins; ins = ins->next) {
 495                         if (MONO_IS_PHI (ins)) {
 496                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 497                                 var = get_vreg_to_inst (cfg, ins->dreg);
 498
 499                                 /* Check for PHI nodes where all the inputs are the same */
 500                                 first = ins->inst_phi_args [1];
 501
 502                                 for (j = 1; j < bb->in_count; ++j)
 503                                         if (first != ins->inst_phi_args [j + 1])
 504                                                 break;
 505
 506                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 507                                         ins->opcode = op_phi_to_move (ins->opcode);
 508                                         if (ins->opcode == OP_VMOVE)
 509                                                 g_assert (ins->klass);
 510                                         ins->sreg1 = first;
 511                                 } else {
 512                                         for (j = 0; j < bb->in_count; j++) {
 513                                                 MonoBasicBlock *pred = bb->in_bb [j];
 514                                                 int sreg = ins->inst_phi_args [j + 1];
 515
 516                                                 if (cfg->verbose_level >= 4)
 517                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 518                                                 if (var->dreg != sreg) {
 519                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 520                                                         if (move->opcode == OP_VMOVE) {
 521                                                                 g_assert (ins->klass);
 522                                                                 move->klass = ins->klass;
 523                                                         }
 524                                                         move->dreg = var->dreg;
 525                                                         move->sreg1 = sreg;
 526                                                         mono_add_ins_to_end (pred, move);
 527                                                 }
 528                                         }
 529
 530                                         NULLIFY_INS (ins);
 531                                 }
 532                         }
 533                 }
 534         }
 535
 536         if (cfg->verbose_level >= 4) {
 537                 for (i = 0; i < cfg->num_bblocks; ++i) {
 538                         MonoBasicBlock *bb = cfg->bblocks [i];
 539
 540                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 541                 }
 542         }
 543
 544         /*
 545          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 546          * the variables if possible. Since the newly introduced SSA variables don't
 547          * have overlapping live ranges (because we don't do agressive optimization), we
 548          * can coalesce them into the original variable.
 549          */
 550
 551         for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
 552                 MonoBasicBlock *bb = cfg->bblocks [bbindex];
 553
 554                 for (ins = bb->code; ins; ins = ins->next) {
 555                         const char *spec = INS_INFO (ins->opcode);
 556                         int num_sregs;
 557                         int sregs [MONO_MAX_SRC_REGS];
 558
 559                         if (ins->opcode == OP_NOP)
 560                                 continue;
 561
 562                         if (spec [MONO_INST_DEST] != ' ') {
 563                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 564
 565                                 if (var) {
 566                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 567
 568                                         /*
 569                                          * The third condition avoids coalescing with variables eliminated
 570                                          * during deadce.
 571                                          */
 572                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 573                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 574                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 575                                         }
 576                                 }
 577                         }
 578
 579                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 580                         for (i = 0; i < num_sregs; ++i) {
 581                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 582
 583                                 if (var) {
 584                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 585
 586                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 587                                                 printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
 588                                                 sregs [i] = cfg->varinfo [vmv->reg]->dreg;
 589                                         }
 590                                 }
 591                         }
 592                         mono_inst_set_src_registers (ins, sregs);
 593                 }
 594         }
 595
 596         for (i = 0; i < cfg->num_varinfo; ++i) {
 597                 MONO_VARINFO (cfg, i)->reg = -1;
 598         }
 599
 600         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 601                 unlink_unused_bblocks (cfg);
 602
 603         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 604
 605         cfg->comp_done &= ~MONO_COMP_SSA;
 606 }
 607
 608 static void
 609 mono_ssa_create_def_use (MonoCompile *cfg)
 610 {
 611         MonoBasicBlock *bb;
 612         MonoInst *ins;
 613         int i;
 614
 615         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 616
 617         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 618                 for (ins = bb->code; ins; ins = ins->next) {
 619                         const char *spec = INS_INFO (ins->opcode);
 620                         MonoMethodVar *info;
 621                         int num_sregs;
 622                         int sregs [MONO_MAX_SRC_REGS];
 623
 624                         if (ins->opcode == OP_NOP)
 625                                 continue;
 626
 627                         /* SREGs */
 628                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 629                         for (i = 0; i < num_sregs; ++i) {
 630                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 631                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 632                                         record_use (cfg, var, bb, ins);
 633                         }
 634
 635                         if (MONO_IS_STORE_MEMBASE (ins)) {
 636                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 637                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 638                                         record_use (cfg, var, bb, ins);
 639                         }
 640
 641                         if (MONO_IS_PHI (ins)) {
 642                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 643                                         g_assert (ins->inst_phi_args [i] != -1);
 644                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 645                                 }
 646                         }
 647
 648                         /* DREG */
 649                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 650                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 651
 652                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 653                                         info = MONO_VARINFO (cfg, var->inst_c0);
 654                                         info->def = ins;
 655                                         info->def_bb = bb;
 656                                 }
 657                         }
 658                 }
 659         }
 660
 661         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 662 }
 663
 664 static void
 665 mono_ssa_copyprop (MonoCompile *cfg)
 666 {
 667         int i, index;
 668         GList *l;
 669
 670         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 671
 672         for (index = 0; index < cfg->num_varinfo; ++index) {
 673                 MonoInst *var = cfg->varinfo [index];
 674                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 675
 676                 if (info->def && (MONO_IS_MOVE (info->def))) {
 677                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 678
 679                         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))) {
 680                                 /* Rewrite all uses of var to be uses of var2 */
 681                                 int dreg = var->dreg;
 682                                 int sreg1 = var2->dreg;
 683
 684                                 l = info->uses;
 685                                 while (l) {
 686                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 687                                         MonoInst *ins = u->inst;
 688                                         GList *next = l->next;
 689                                         int num_sregs;
 690                                         int sregs [MONO_MAX_SRC_REGS];
 691
 692                                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 693                                         for (i = 0; i < num_sregs; ++i) {
 694                                                 if (sregs [i] == dreg)
 695                                                         break;
 696                                         }
 697                                         if (i < num_sregs) {
 698                                                 g_assert (sregs [i] == dreg);
 699                                                 sregs [i] = sreg1;
 700                                                 mono_inst_set_src_registers (ins, sregs);
 701                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 702                                                 ins->dreg = sreg1;
 703                                         } else if (MONO_IS_PHI (ins)) {
 704                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 705                                                         int sreg = ins->inst_phi_args [i];
 706                                                         if (sreg == var->dreg)
 707                                                                 break;
 708                                                 }
 709                                                 g_assert (i > 0);
 710                                                 ins->inst_phi_args [i] = sreg1;
 711                                         }
 712                                         else
 713                                                 g_assert_not_reached ();
 714
 715                                         record_use (cfg, var2, u->bb, ins);
 716
 717                                         l = next;
 718                                 }
 719
 720                                 info->uses = NULL;
 721                         }
 722                 }
 723         }
 724
 725         if (cfg->verbose_level >= 4) {
 726                 MonoBasicBlock *bb;
 727
 728                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 729                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 730         }
 731 }
 732
 733 static int
 734 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 735 {
 736         MonoInst *args [MONO_MAX_SRC_REGS];
 737         int rs [MONO_MAX_SRC_REGS];
 738         MonoInst *c0;
 739         gboolean const_args = TRUE;
 740         const char *spec = INS_INFO (ins->opcode);
 741         int num_sregs, i;
 742         int sregs [MONO_MAX_SRC_REGS];
 743
 744         /* Short-circuit this */
 745         if (ins->opcode == OP_ICONST) {
 746                 *res = ins;
 747                 return 1;
 748         }
 749
 750         if (ins->opcode == OP_NOP)
 751                 return 2;
 752
 753         num_sregs = mono_inst_get_src_registers (ins, sregs);
 754         for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
 755                 args [i] = NULL;
 756         for (i = 0; i < num_sregs; ++i) {
 757                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 758
 759                 rs [i] = 2;
 760                 args [i] = carray [sregs [i]];
 761                 if (args [i])
 762                         rs [i] = 1;
 763                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 764                         rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 765                 if (rs [i] != 1)
 766                         const_args = FALSE;
 767         }
 768
 769         c0 = NULL;
 770
 771         if (num_sregs > 0 && const_args) {
 772                 g_assert (num_sregs <= 2);
 773                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 774                         // Cached value
 775                         *res = carray [ins->dreg];
 776                         return 1;
 777                 }
 778                 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
 779                 if (c0) {
 780                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 781                                 printf ("\t cfold -> ");
 782                                 mono_print_ins (c0);
 783                         }
 784                         *res = c0;
 785                         return 1;
 786                 }
 787                 else
 788                         /* Can't cfold this ins */
 789                         return 2;
 790         }
 791
 792         if (num_sregs == 0)
 793                 return 2;
 794         for (i = 0; i < num_sregs; ++i) {
 795                 if (rs [i] == 2)
 796                         return 2;
 797         }
 798         return 0;
 799 }
 800
 801 static inline void
 802 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 803 {
 804         if (info->cpstate >= state)
 805                 return;
 806
 807         info->cpstate = state;
 808
 809         if (G_UNLIKELY (cfg->verbose_level > 1))
 810                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 811
 812         if (state == 1)
 813                 g_assert (c0);
 814
 815         carray [cfg->varinfo [info->idx]->dreg] = c0;
 816
 817         if (!g_list_find (*cvars, info)) {
 818                 *cvars = g_list_prepend (*cvars, info);
 819         }
 820 }
 821
 822 static inline void
 823 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 824 {
 825         if (G_UNLIKELY (cfg->verbose_level > 1))
 826                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 827
 828     if (!(bb->flags &  BB_REACHABLE)) {
 829             bb->flags |= BB_REACHABLE;
 830                 *bblist = g_list_prepend (*bblist, bb);
 831         }
 832 }
 833
 834 static void
 835 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 836 {
 837         const char *spec = INS_INFO (ins->opcode);
 838
 839         if (ins->opcode == OP_NOP)
 840                 return;
 841
 842         if (cfg->verbose_level > 1)
 843                 mono_print_ins (ins);
 844
 845         /* FIXME: Support longs/floats */
 846         /* FIXME: Work on vregs as well */
 847
 848         if (MONO_IS_PHI (ins)) {
 849                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 850                 MonoInst *c0 = NULL;
 851                 int j;
 852
 853                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 854                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 855                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 856                         MonoInst *src = mv->def;
 857
 858                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 859                                 continue;
 860
 861                         if (!mv->def || !src || mv->cpstate == 2) {
 862                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 863                                 break;
 864                         }
 865
 866                         if (mv->cpstate == 0)
 867                                 continue;
 868
 869                         g_assert (carray [var->dreg]);
 870
 871                         if (!c0)
 872                                 c0 = carray [var->dreg];
 873
 874                         /* FIXME: */
 875                         if (c0->opcode != OP_ICONST) {
 876                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 877                                 break;
 878                         }
 879
 880                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 881                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 882                                 break;
 883                         }
 884                 }
 885
 886                 if (c0 && info->cpstate < 1) {
 887                         change_varstate (cfg, cvars, info, 1, c0, carray);
 888
 889                         g_assert (c0->opcode == OP_ICONST);
 890                 }
 891         }
 892         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 893                 MonoInst *var, *c0;
 894                 int state;
 895
 896                 if (spec [MONO_INST_DEST] !=  ' ')
 897                         var = get_vreg_to_inst (cfg, ins->dreg);
 898                 else
 899                         var = NULL;
 900
 901                 c0 = NULL;
 902                 state = evaluate_ins (cfg, ins, &c0, carray);
 903
 904                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 905                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 906
 907                         if (info->cpstate < 2) {
 908                                 if (state == 1)
 909                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 910                                 else if (state == 2)
 911                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 912                         }
 913                 }
 914                 else if (!var && (ins->dreg != -1)) {
 915                         /*
 916                          * We don't record def-use information for local vregs since it would be
 917                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 918                          * the same bblock, so they will be examined after the definition.
 919                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 920                          */
 921                         if (c0) {
 922                                 carray [ins->dreg] = c0;
 923                         } else {
 924                                 if (carray [ins->dreg]) {
 925                                         /*
 926                                          * The state of the vreg changed from constant to non-constant
 927                                          * -> need to rescan the whole bblock.
 928                                          */
 929                                         carray [ins->dreg] = NULL;
 930                                         /* FIXME: Speed this up */
 931
 932                                         if (!g_list_find (*bblist, bb))
 933                                                 *bblist = g_list_prepend (*bblist, bb);
 934                                 }
 935                         }
 936                 }
 937
 938                 if (MONO_IS_JUMP_TABLE (ins)) {
 939                         int i;
 940                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
 941
 942                         if (!ins->next || ins->next->opcode != OP_PADD) {
 943                                 /* The PADD was optimized away */
 944                                 /* FIXME: handle this as well */
 945                                 for (i = 0; i < table->table_size; i++)
 946                                         if (table->table [i])
 947                                                 add_cprop_bb (cfg, table->table [i], bblist);
 948                                 return;
 949                         }
 950
 951                         g_assert (ins->next->opcode == OP_PADD);
 952                         g_assert (ins->next->sreg1 == ins->dreg);
 953
 954                         if (carray [ins->next->sreg2]) {
 955 #if SIZEOF_REGISTER == 8
 956                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
 957 #else
 958                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
 959 #endif
 960                                 if ((idx < 0) || (idx >= table->table_size))
 961                                         /* Out-of-range, no branch is executed */
 962                                         return;
 963                                 else
 964                                         if (table->table [idx])
 965                                                 add_cprop_bb (cfg, table->table [idx], bblist);
 966                         }
 967                         else {
 968                                 for (i = 0; i < table->table_size; i++)
 969                                         if (table->table [i])
 970                                                 add_cprop_bb (cfg, table->table [i], bblist);
 971                         }
 972                 }
 973
 974                 if (ins->opcode == OP_SWITCH) {
 975                         int i;
 976                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)ins->inst_p0;
 977
 978                         for (i = 0; i < table->table_size; i++)
 979                                 if (table->table [i])
 980                                         add_cprop_bb (cfg, table->table [i], bblist);
 981                 }
 982
 983                 /* Handle COMPARE+BRCOND pairs */
 984                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
 985                         if (c0) {
 986                                 g_assert (c0->opcode == OP_ICONST);
 987
 988                                 if (c0->inst_c0)
 989                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
 990                                 else
 991                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
 992                         }
 993                         else {
 994                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
 995                         }
 996
 997                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
 998                 }
 999         } else if (ins->opcode == OP_BR) {
1000                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1001         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1002                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1003                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1004                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1005                         if (ins->inst_false_bb)
1006                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1007         } else {
1008                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1009                         if (ins->inst_false_bb)
1010                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1011                 }
1012         }
1013 }
1014
1015 /**
1016  * fold_ins:
1017  *
1018  *   Replace INS with its constant value, if it exists
1019  */
1020 static void
1021 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1022 {
1023         const char *spec = INS_INFO (ins->opcode);
1024         int opcode2;
1025         int num_sregs = mono_inst_get_num_src_registers (ins);
1026
1027         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1028                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1029                         /* Perform constant folding */
1030                         /* FIXME: */
1031                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1032                         ins->opcode = OP_ICONST;
1033                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1034                         MONO_INST_NULLIFY_SREGS (ins);
1035                 } else if (num_sregs == 2 && carray [ins->sreg2]) {
1036                         /* Perform op->op_imm conversion */
1037                         opcode2 = mono_op_to_op_imm (ins->opcode);
1038                         if (opcode2 != -1) {
1039                                 ins->opcode = opcode2;
1040                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1041                                 ins->sreg2 = -1;
1042
1043                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1044                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1045                         }
1046                 } else {
1047                         /* FIXME: Handle 3 op insns */
1048                 }
1049
1050                 if (MONO_IS_JUMP_TABLE (ins)) {
1051                         int i;
1052                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1053
1054                         if (!ins->next || ins->next->opcode != OP_PADD) {
1055                                 /* The PADD was optimized away */
1056                                 /* FIXME: handle this as well */
1057                                 return;
1058                         }
1059
1060                         g_assert (ins->next->opcode == OP_PADD);
1061                         g_assert (ins->next->sreg1 == ins->dreg);
1062                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1063
1064                         if (carray [ins->next->sreg2]) {
1065                                 /* Convert to a simple branch */
1066 #if SIZEOF_REGISTER == 8
1067                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1068 #else
1069                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1070 #endif
1071
1072                                 if (!((idx >= 0) && (idx < table->table_size))) {
1073                                         /* Out of range, eliminate the whole switch */
1074                                         for (i = 0; i < table->table_size; ++i) {
1075                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1076                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1077                                         }
1078
1079                                         NULLIFY_INS (ins);
1080                                         NULLIFY_INS (ins->next);
1081                                         NULLIFY_INS (ins->next->next);
1082                                         if (ins->next->next->next)
1083                                                 NULLIFY_INS (ins->next->next->next);
1084
1085                                         return;
1086                                 }
1087
1088                                 if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
1089                                         /* A one-way switch which got optimized away */
1090                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1091                                                 printf ("\tNo cfold on ");
1092                                                 mono_print_ins (ins);
1093                                         }
1094                                         return;
1095                                 }
1096
1097                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1098                                         printf ("\tcfold on ");
1099                                         mono_print_ins (ins);
1100                                 }
1101
1102                                 /* Unlink target bblocks */
1103                                 for (i = 0; i < table->table_size; ++i) {
1104                                         if (table->table [i] != table->table [idx]) {
1105                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1106                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1107                                         }
1108                                 }
1109
1110                                 /* Change the OP_BR_REG to a simple branch */
1111                                 ins->next->next->next->opcode = OP_BR;
1112                                 ins->next->next->next->inst_target_bb = table->table [idx];
1113                                 ins->next->next->next->sreg1 = -1;
1114
1115                                 /* Nullify the other instructions */
1116                                 NULLIFY_INS (ins);
1117                                 NULLIFY_INS (ins->next);
1118                                 NULLIFY_INS (ins->next->next);
1119                         }
1120                 }
1121         }
1122         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1123                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1124                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1125                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1126                         ins->opcode = OP_BR;
1127                         ins->inst_target_bb = ins->inst_true_bb;
1128                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1129                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1130                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1131                         ins->opcode = OP_BR;
1132                         ins->inst_target_bb = ins->inst_false_bb;
1133                 }
1134         }
1135 }
1136
1137 void
1138 mono_ssa_cprop (MonoCompile *cfg)
1139 {
1140         MonoInst **carray;
1141         MonoBasicBlock *bb;
1142         GList *bblock_list, *cvars;
1143         GList *tmp;
1144         int i;
1145         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1146
1147         carray = g_new0 (MonoInst*, cfg->next_vreg);
1148
1149         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1150                 mono_ssa_create_def_use (cfg);
1151
1152         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1153         cfg->bb_entry->flags |= BB_REACHABLE;
1154
1155         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1156
1157         for (i = 0; i < cfg->num_varinfo; i++) {
1158                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1159                 if (!info->def)
1160                         info->cpstate = 2;
1161         }
1162
1163         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1164                 /*
1165                  * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1166                  * that would still allow unreachable try's to be removed.
1167                  */
1168                 if (bb->region)
1169                         add_cprop_bb (cfg, bb, &bblock_list);
1170         }
1171
1172         cvars = NULL;
1173
1174         while (bblock_list) {
1175                 MonoInst *inst;
1176
1177                 bb = (MonoBasicBlock *)bblock_list->data;
1178
1179                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1180
1181                 g_assert (bb->flags &  BB_REACHABLE);
1182
1183                 /*
1184                  * Some bblocks are linked to 2 others even through they fall through to the
1185                  * next bblock.
1186                  */
1187                 if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
1188                         for (i = 0; i < bb->out_count; ++i)
1189                                 add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
1190                 }
1191
1192                 if (cfg->verbose_level > 1)
1193                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1194
1195                 for (inst = bb->code; inst; inst = inst->next) {
1196                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1197                 }
1198
1199                 while (cvars) {
1200                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1201                         cvars = g_list_delete_link (cvars, cvars);
1202
1203                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1204                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1205                                 if (!(ui->bb->flags & BB_REACHABLE))
1206                                         continue;
1207                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1208                         }
1209                 }
1210         }
1211
1212         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1213                 MonoInst *inst;
1214                 for (inst = bb->code; inst; inst = inst->next) {
1215                         fold_ins (cfg, bb, inst, carray);
1216                 }
1217         }
1218
1219         g_free (carray);
1220
1221         cfg->comp_done |= MONO_COMP_REACHABILITY;
1222
1223         /* fixme: we should update usage infos during cprop, instead of computing it again */
1224         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1225         for (i = 0; i < cfg->num_varinfo; i++) {
1226                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1227                 info->def = NULL;
1228                 info->uses = NULL;
1229         }
1230 }
1231
1232 static inline void
1233 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1234 {
1235         GList *tmp;
1236
1237         *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1238
1239         for (tmp = use->uses; tmp; tmp = tmp->next) {
1240                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1241                 if (ui->inst == var->def) {
1242                         /* from the mempool */
1243                         use->uses = g_list_remove_link (use->uses, tmp);
1244                         break;
1245                 }
1246         }
1247 }
1248
1249 void
1250 mono_ssa_deadce (MonoCompile *cfg)
1251 {
1252         int i;
1253         GList *work_list;
1254
1255         g_assert (cfg->comp_done & MONO_COMP_SSA);
1256
1257         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1258
1259         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1260                 mono_ssa_create_def_use (cfg);
1261
1262         mono_ssa_copyprop (cfg);
1263
1264         work_list = NULL;
1265         for (i = 0; i < cfg->num_varinfo; i++) {
1266                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1267                 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1268         }
1269
1270         while (work_list) {
1271                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1272                 work_list = g_list_remove_link (work_list, work_list);
1273
1274                 /*
1275                  * The second part of the condition happens often when PHI nodes have their dreg
1276                  * as one of their arguments due to the fact that we use the original vars.
1277                  */
1278                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1279                         MonoInst *def = info->def;
1280
1281                         /* Eliminating FMOVE could screw up the fp stack */
1282                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1283                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1284                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1285                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1286                                 NULLIFY_INS (def);
1287                                 info->reg = -1;
1288                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1289                                 NULLIFY_INS (def);
1290                                 info->reg = -1;
1291                         } else if (MONO_IS_PHI (def)) {
1292                                 int j;
1293                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1294                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1295                                         add_to_dce_worklist (cfg, info, u, &work_list);
1296                                 }
1297                                 NULLIFY_INS (def);
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 void
1347 mono_ssa_loop_invariant_code_motion (MonoCompile *cfg)
1348 {
1349         MonoBasicBlock *bb, *h, *idom;
1350         MonoInst *ins, *n, *tins;
1351         int i;
1352
1353         g_assert (cfg->comp_done & MONO_COMP_SSA);
1354         if (!(cfg->comp_done & MONO_COMP_LOOPS) || !(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1355                 return;
1356
1357         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1358                 GList *lp = bb->loop_blocks;
1359
1360                 if (!lp)
1361                         continue;
1362                 h = (MonoBasicBlock *)lp->data;
1363                 if (bb != h)
1364                         continue;
1365                 MONO_BB_FOR_EACH_INS_SAFE (bb, n, ins) {
1366                         /*
1367                          * Try to move instructions out of loop headers into the preceeding bblock.
1368                          */
1369                         if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS || ins->opcode == OP_AOTCONST || ins->opcode == OP_GENERIC_CLASS_INIT) {
1370                                 gboolean skip;
1371                                 int sreg;
1372
1373                                 idom = h->idom;
1374                                 /*
1375                                  * h->nesting is needed to work around:
1376                                  * http://llvm.org/bugs/show_bug.cgi?id=17868
1377                                  */
1378                                 if (!(idom && idom->last_ins && idom->last_ins->opcode == OP_BR && idom->last_ins->inst_target_bb == h && h->nesting == 1)) {
1379                                         continue;
1380                                 }
1381
1382                                 /*
1383                                  * Make sure there are no instructions with side effects before ins.
1384                                  */
1385                                 skip = FALSE;
1386                                 MONO_BB_FOR_EACH_INS (bb, tins) {
1387                                         if (tins == ins)
1388                                                 break;
1389                                         if (!MONO_INS_HAS_NO_SIDE_EFFECT (tins)) {
1390                                                 skip = TRUE;
1391                                                 break;
1392                                         }
1393                                 }
1394                                 if (skip) {
1395                                         /*
1396                                           printf ("%s\n", mono_method_full_name (cfg->method, TRUE));
1397                                           mono_print_ins (tins);
1398                                         */
1399                                         continue;
1400                                 }
1401
1402                                 /* Make sure we don't move the instruction before the def of its sreg */
1403                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS)
1404                                         sreg = ins->sreg1;
1405                                 else
1406                                         sreg = -1;
1407                                 if (sreg != -1) {
1408                                         MonoInst *tins, *var;
1409
1410                                         skip = FALSE;
1411                                         for (tins = ins->prev; tins; tins = tins->prev) {
1412                                                 const char *spec = INS_INFO (tins->opcode);
1413
1414                                                 if (tins->opcode == OP_MOVE && tins->dreg == sreg) {
1415                                                         sreg = tins->sreg1;
1416                                                 } if (spec [MONO_INST_DEST] != ' ' && tins->dreg == sreg) {
1417                                                         skip = TRUE;
1418                                                         break;
1419                                                 }
1420                                         }
1421                                         if (skip)
1422                                                 continue;
1423                                         var = get_vreg_to_inst (cfg, sreg);
1424                                         if (var && (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1425                                                 continue;
1426                                         ins->sreg1 = sreg;
1427                                 }
1428
1429                                 if (cfg->verbose_level > 1) {
1430                                         printf ("licm in BB%d on ", bb->block_num);
1431                                         mono_print_ins (ins);
1432                                 }
1433                                 //{ static int count = 0; count ++; printf ("%d\n", count); }
1434                                 MONO_REMOVE_INS (bb, ins);
1435                                 mono_bblock_insert_before_ins (idom, idom->last_ins, ins);
1436                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN)
1437                                         idom->has_array_access = TRUE;
1438                         }
1439                 }
1440         }
1441
1442         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1443         for (i = 0; i < cfg->num_varinfo; i++) {
1444                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1445                 info->def = NULL;
1446                 info->uses = NULL;
1447         }
1448 }
1449
1450 #endif /* DISABLE_JIT */