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