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         g_assert (!cfg->disable_ssa);
 344
 345         if (cfg->verbose_level >= 4)
 346                 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
 347
 348 #ifdef CREATE_PRUNED_SSA
 349         /* we need liveness for pruned SSA */
 350         if (!(cfg->comp_done & MONO_COMP_LIVENESS))
 351                 mono_analyze_liveness (cfg);
 352 #endif
 353
 354         mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
 355
 356         bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
 357         buf = buf_start = g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
 358
 359         for (i = 0; i < cfg->num_varinfo; ++i) {
 360                 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
 361                 buf += bitsize;
 362                 vinfo [i].idx = i;
 363                 /* implicit reference at start */
 364                 if (cfg->varinfo [i]->opcode == OP_ARG)
 365                         mono_bitset_set_fast (vinfo [i].def_in, 0);
 366         }
 367
 368         for (i = 0; i < cfg->num_bblocks; ++i) {
 369                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 370                         if (ins->opcode == OP_NOP)
 371                                 continue;
 372
 373                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 374                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 375                         }
 376                 }
 377         }
 378
 379         /* insert phi functions */
 380         for (i = 0; i < cfg->num_varinfo; ++i) {
 381                 MonoInst *var = cfg->varinfo [i];
 382
 383 #if SIZEOF_REGISTER == 4
 384                 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
 385                         continue;
 386 #endif
 387                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 388                         continue;
 389
 390                 /* Most variables have only one definition */
 391                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 392                         continue;
 393
 394                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 395
 396                 if (cfg->verbose_level >= 4) {
 397                         if (mono_bitset_count (set) > 0) {
 398                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 399                                 mono_blockset_print (cfg, set, "", -1);
 400                         }
 401                 }
 402
 403                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 404                         MonoBasicBlock *bb = cfg->bblocks [idx];
 405
 406                         /* fixme: create pruned SSA? we would need liveness information for that */
 407
 408                         if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
 409                                 continue;
 410
 411                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 412                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 413                                 continue;
 414                         }
 415
 416                         NEW_PHI (cfg, ins, i);
 417
 418                         switch (var->type) {
 419                         case STACK_I4:
 420                         case STACK_I8:
 421                         case STACK_PTR:
 422                         case STACK_MP:
 423                         case STACK_OBJ:
 424                                 ins->opcode = OP_PHI;
 425                                 break;
 426                         case STACK_R8:
 427                                 ins->opcode = OP_FPHI;
 428                                 break;
 429                         case STACK_VTYPE:
 430                                 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
 431                                 break;
 432                         }
 433
 434                         if (var->inst_vtype->byref)
 435                                 ins->klass = mono_defaults.int_class;
 436                         else
 437                                 ins->klass = var->klass;
 438
 439                         ins->inst_phi_args =  mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 440                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 441
 442                         /* For debugging */
 443                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 444                                 ins->inst_phi_args [j + 1] = -1;
 445
 446                         ins->dreg = cfg->varinfo [i]->dreg;
 447
 448                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 449
 450 #ifdef DEBUG_SSA
 451                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 452 #endif
 453                 }
 454         }
 455
 456         /* free the stuff */
 457         g_free (vinfo);
 458         g_free (buf_start);
 459
 460         /* Renaming phase */
 461
 462         stack = alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 463         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 464
 465         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 466         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 467         stack_history_size = 10240;
 468         stack_history = g_new (RenameInfo, stack_history_size);
 469         originals = g_new0 (gboolean, cfg->num_varinfo);
 470         mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 471         g_free (stack_history);
 472         g_free (originals);
 473         g_free (lvreg_stack);
 474         g_free (lvreg_defined);
 475
 476         if (cfg->verbose_level >= 4)
 477                 printf ("\nEND COMPUTE SSA.\n\n");
 478
 479         cfg->comp_done |= MONO_COMP_SSA;
 480 }
 481
 482 void
 483 mono_ssa_remove (MonoCompile *cfg)
 484 {
 485         MonoInst *ins, *var, *move;
 486         int bbindex, i, j, first;
 487
 488         g_assert (cfg->comp_done & MONO_COMP_SSA);
 489
 490         for (i = 0; i < cfg->num_bblocks; ++i) {
 491                 MonoBasicBlock *bb = cfg->bblocks [i];
 492
 493                 if (cfg->verbose_level >= 4)
 494                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 495
 496                 for (ins = bb->code; ins; ins = ins->next) {
 497                         if (MONO_IS_PHI (ins)) {
 498                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 499                                 var = get_vreg_to_inst (cfg, ins->dreg);
 500
 501                                 /* Check for PHI nodes where all the inputs are the same */
 502                                 first = ins->inst_phi_args [1];
 503
 504                                 for (j = 1; j < bb->in_count; ++j)
 505                                         if (first != ins->inst_phi_args [j + 1])
 506                                                 break;
 507
 508                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 509                                         ins->opcode = op_phi_to_move (ins->opcode);
 510                                         if (ins->opcode == OP_VMOVE)
 511                                                 g_assert (ins->klass);
 512                                         ins->sreg1 = first;
 513                                 } else {
 514                                         for (j = 0; j < bb->in_count; j++) {
 515                                                 MonoBasicBlock *pred = bb->in_bb [j];
 516                                                 int sreg = ins->inst_phi_args [j + 1];
 517
 518                                                 if (cfg->verbose_level >= 4)
 519                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 520                                                 if (var->dreg != sreg) {
 521                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 522                                                         if (move->opcode == OP_VMOVE) {
 523                                                                 g_assert (ins->klass);
 524                                                                 move->klass = ins->klass;
 525                                                         }
 526                                                         move->dreg = var->dreg;
 527                                                         move->sreg1 = sreg;
 528                                                         mono_add_ins_to_end (pred, move);
 529                                                 }
 530                                         }
 531
 532                                         ins->opcode = OP_NOP;
 533                                         ins->dreg = -1;
 534                                 }
 535                         }
 536                 }
 537         }
 538
 539         if (cfg->verbose_level >= 4) {
 540                 for (i = 0; i < cfg->num_bblocks; ++i) {
 541                         MonoBasicBlock *bb = cfg->bblocks [i];
 542
 543                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 544                 }
 545         }
 546
 547         /*
 548          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 549          * the variables if possible. Since the newly introduced SSA variables don't
 550          * have overlapping live ranges (because we don't do agressive optimization), we
 551          * can coalesce them into the original variable.
 552          */
 553
 554         for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
 555                 MonoBasicBlock *bb = cfg->bblocks [bbindex];
 556
 557                 for (ins = bb->code; ins; ins = ins->next) {
 558                         const char *spec = INS_INFO (ins->opcode);
 559                         int num_sregs;
 560                         int sregs [MONO_MAX_SRC_REGS];
 561
 562                         if (ins->opcode == OP_NOP)
 563                                 continue;
 564
 565                         if (spec [MONO_INST_DEST] != ' ') {
 566                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 567
 568                                 if (var) {
 569                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 570
 571                                         /*
 572                                          * The third condition avoids coalescing with variables eliminated
 573                                          * during deadce.
 574                                          */
 575                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 576                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 577                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 578                                         }
 579                                 }
 580                         }
 581
 582                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 583                         for (i = 0; i < num_sregs; ++i) {
 584                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 585
 586                                 if (var) {
 587                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 588
 589                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 590                                                 printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
 591                                                 sregs [i] = cfg->varinfo [vmv->reg]->dreg;
 592                                         }
 593                                 }
 594                         }
 595                         mono_inst_set_src_registers (ins, sregs);
 596                 }
 597         }
 598
 599         for (i = 0; i < cfg->num_varinfo; ++i) {
 600                 MONO_VARINFO (cfg, i)->reg = -1;
 601         }
 602
 603         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 604                 unlink_unused_bblocks (cfg);
 605
 606         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 607
 608         cfg->comp_done &= ~MONO_COMP_SSA;
 609 }
 610
 611 static void
 612 mono_ssa_create_def_use (MonoCompile *cfg)
 613 {
 614         MonoBasicBlock *bb;
 615         MonoInst *ins;
 616         int i;
 617
 618         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 619
 620         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 621                 for (ins = bb->code; ins; ins = ins->next) {
 622                         const char *spec = INS_INFO (ins->opcode);
 623                         MonoMethodVar *info;
 624                         int num_sregs;
 625                         int sregs [MONO_MAX_SRC_REGS];
 626
 627                         if (ins->opcode == OP_NOP)
 628                                 continue;
 629
 630                         /* SREGs */
 631                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 632                         for (i = 0; i < num_sregs; ++i) {
 633                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 634                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 635                                         record_use (cfg, var, bb, ins);
 636                         }
 637
 638                         if (MONO_IS_STORE_MEMBASE (ins)) {
 639                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 640                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 641                                         record_use (cfg, var, bb, ins);
 642                         }
 643
 644                         if (MONO_IS_PHI (ins)) {
 645                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 646                                         g_assert (ins->inst_phi_args [i] != -1);
 647                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 648                                 }
 649                         }
 650
 651                         /* DREG */
 652                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 653                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 654
 655                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 656                                         info = MONO_VARINFO (cfg, var->inst_c0);
 657                                         info->def = ins;
 658                                         info->def_bb = bb;
 659                                 }
 660                         }
 661                 }
 662         }
 663
 664         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 665 }
 666
 667 static void
 668 mono_ssa_copyprop (MonoCompile *cfg)
 669 {
 670         int i, index;
 671         GList *l;
 672
 673         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 674
 675         for (index = 0; index < cfg->num_varinfo; ++index) {
 676                 MonoInst *var = cfg->varinfo [index];
 677                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 678
 679                 if (info->def && (MONO_IS_MOVE (info->def))) {
 680                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 681
 682                         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))) {
 683                                 /* Rewrite all uses of var to be uses of var2 */
 684                                 int dreg = var->dreg;
 685                                 int sreg1 = var2->dreg;
 686                                 const char *spec;
 687
 688                                 l = info->uses;
 689                                 while (l) {
 690                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 691                                         MonoInst *ins = u->inst;
 692                                         GList *next = l->next;
 693                                         int num_sregs;
 694                                         int sregs [MONO_MAX_SRC_REGS];
 695
 696                                         spec = INS_INFO (ins->opcode);
 697
 698                                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 699                                         for (i = 0; i < num_sregs; ++i) {
 700                                                 if (sregs [i] == dreg)
 701                                                         break;
 702                                         }
 703                                         if (i < num_sregs) {
 704                                                 g_assert (sregs [i] == dreg);
 705                                                 sregs [i] = sreg1;
 706                                                 mono_inst_set_src_registers (ins, sregs);
 707                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 708                                                 ins->dreg = sreg1;
 709                                         } else if (MONO_IS_PHI (ins)) {
 710                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 711                                                         int sreg = ins->inst_phi_args [i];
 712                                                         if (sreg == var->dreg)
 713                                                                 break;
 714                                                 }
 715                                                 g_assert (i > 0);
 716                                                 ins->inst_phi_args [i] = sreg1;
 717                                         }
 718                                         else
 719                                                 g_assert_not_reached ();
 720
 721                                         record_use (cfg, var2, u->bb, ins);
 722
 723                                         l = next;
 724                                 }
 725
 726                                 info->uses = NULL;
 727                         }
 728                 }
 729         }
 730
 731         if (cfg->verbose_level >= 4) {
 732                 MonoBasicBlock *bb;
 733
 734                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 735                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 736         }
 737 }
 738
 739 static int
 740 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 741 {
 742         MonoInst *args [MONO_MAX_SRC_REGS];
 743         int rs [MONO_MAX_SRC_REGS];
 744         MonoInst *c0;
 745         gboolean const_args = TRUE;
 746         const char *spec = INS_INFO (ins->opcode);
 747         int num_sregs, i;
 748         int sregs [MONO_MAX_SRC_REGS];
 749
 750         /* Short-circuit this */
 751         if (ins->opcode == OP_ICONST) {
 752                 *res = ins;
 753                 return 1;
 754         }
 755
 756         if (ins->opcode == OP_NOP)
 757                 return 2;
 758
 759         num_sregs = mono_inst_get_src_registers (ins, sregs);
 760         for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
 761                 args [i] = NULL;
 762         for (i = 0; i < num_sregs; ++i) {
 763                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 764
 765                 rs [i] = 2;
 766                 args [i] = carray [sregs [i]];
 767                 if (args [i])
 768                         rs [i] = 1;
 769                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 770                         rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 771                 if (rs [i] != 1)
 772                         const_args = FALSE;
 773         }
 774
 775         c0 = NULL;
 776
 777         if (num_sregs > 0 && const_args) {
 778                 g_assert (num_sregs <= 2);
 779                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 780                         // Cached value
 781                         *res = carray [ins->dreg];
 782                         return 1;
 783                 }
 784                 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
 785                 if (c0) {
 786                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 787                                 printf ("\t cfold -> ");
 788                                 mono_print_ins (c0);
 789                         }
 790                         *res = c0;
 791                         return 1;
 792                 }
 793                 else
 794                         /* Can't cfold this ins */
 795                         return 2;
 796         }
 797
 798         if (num_sregs == 0)
 799                 return 2;
 800         for (i = 0; i < num_sregs; ++i) {
 801                 if (rs [i] == 2)
 802                         return 2;
 803         }
 804         return 0;
 805 }
 806
 807 static inline void
 808 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 809 {
 810         if (info->cpstate >= state)
 811                 return;
 812
 813         info->cpstate = state;
 814
 815         if (G_UNLIKELY (cfg->verbose_level > 1))
 816                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 817
 818         if (state == 1)
 819                 g_assert (c0);
 820
 821         carray [cfg->varinfo [info->idx]->dreg] = c0;
 822
 823         if (!g_list_find (*cvars, info)) {
 824                 *cvars = g_list_prepend (*cvars, info);
 825         }
 826 }
 827
 828 static inline void
 829 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 830 {
 831         if (G_UNLIKELY (cfg->verbose_level > 1))
 832                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 833
 834     if (!(bb->flags &  BB_REACHABLE)) {
 835             bb->flags |= BB_REACHABLE;
 836                 *bblist = g_list_prepend (*bblist, bb);
 837         }
 838 }
 839
 840 static void
 841 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 842 {
 843         const char *spec = INS_INFO (ins->opcode);
 844
 845         if (ins->opcode == OP_NOP)
 846                 return;
 847
 848         if (cfg->verbose_level > 1)
 849                 mono_print_ins (ins);
 850
 851         /* FIXME: Support longs/floats */
 852         /* FIXME: Work on vregs as well */
 853
 854         if (MONO_IS_PHI (ins)) {
 855                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 856                 MonoInst *c0 = NULL;
 857                 int j;
 858
 859                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 860                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 861                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 862                         MonoInst *src = mv->def;
 863
 864                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 865                                 continue;
 866
 867                         if (!mv->def || !src || mv->cpstate == 2) {
 868                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 869                                 break;
 870                         }
 871
 872                         if (mv->cpstate == 0)
 873                                 continue;
 874
 875                         g_assert (carray [var->dreg]);
 876
 877                         if (!c0)
 878                                 c0 = carray [var->dreg];
 879
 880                         /* FIXME: */
 881                         if (c0->opcode != OP_ICONST) {
 882                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 883                                 break;
 884                         }
 885
 886                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 887                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 888                                 break;
 889                         }
 890                 }
 891
 892                 if (c0 && info->cpstate < 1) {
 893                         change_varstate (cfg, cvars, info, 1, c0, carray);
 894
 895                         g_assert (c0->opcode == OP_ICONST);
 896                 }
 897         }
 898         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 899                 MonoInst *var, *c0;
 900                 int state;
 901
 902                 if (spec [MONO_INST_DEST] !=  ' ')
 903                         var = get_vreg_to_inst (cfg, ins->dreg);
 904                 else
 905                         var = NULL;
 906
 907                 c0 = NULL;
 908                 state = evaluate_ins (cfg, ins, &c0, carray);
 909
 910                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 911                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 912
 913                         if (info->cpstate < 2) {
 914                                 if (state == 1)
 915                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 916                                 else if (state == 2)
 917                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 918                         }
 919                 }
 920                 else if (!var && (ins->dreg != -1)) {
 921                         /*
 922                          * We don't record def-use information for local vregs since it would be
 923                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 924                          * the same bblock, so they will be examined after the definition.
 925                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 926                          */
 927                         if (c0) {
 928                                 carray [ins->dreg] = c0;
 929                         } else {
 930                                 if (carray [ins->dreg]) {
 931                                         /*
 932                                          * The state of the vreg changed from constant to non-constant
 933                                          * -> need to rescan the whole bblock.
 934                                          */
 935                                         carray [ins->dreg] = NULL;
 936                                         /* FIXME: Speed this up */
 937
 938                                         if (!g_list_find (*bblist, bb))
 939                                                 *bblist = g_list_prepend (*bblist, bb);
 940                                 }
 941                         }
 942                 }
 943
 944                 if (MONO_IS_JUMP_TABLE (ins)) {
 945                         int i;
 946                         MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
 947
 948                         if (!ins->next || ins->next->opcode != OP_PADD) {
 949                                 /* The PADD was optimized away */
 950                                 /* FIXME: handle this as well */
 951                                 for (i = 0; i < table->table_size; i++)
 952                                         if (table->table [i])
 953                                                 add_cprop_bb (cfg, table->table [i], bblist);
 954                                 return;
 955                         }
 956
 957                         g_assert (ins->next->opcode == OP_PADD);
 958                         g_assert (ins->next->sreg1 == ins->dreg);
 959
 960                         if (carray [ins->next->sreg2]) {
 961 #if SIZEOF_REGISTER == 8
 962                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
 963 #else
 964                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
 965 #endif
 966                                 if ((idx < 0) || (idx >= table->table_size))
 967                                         /* Out-of-range, no branch is executed */
 968                                         return;
 969                                 else
 970                                         if (table->table [idx])
 971                                                 add_cprop_bb (cfg, table->table [idx], bblist);
 972                         }
 973                         else {
 974                                 for (i = 0; i < table->table_size; i++)
 975                                         if (table->table [i])
 976                                                 add_cprop_bb (cfg, table->table [i], bblist);
 977                         }
 978                 }
 979
 980                 if (ins->opcode == OP_SWITCH) {
 981                         int i;
 982                         MonoJumpInfoBBTable *table = ins->inst_p0;
 983
 984                         for (i = 0; i < table->table_size; i++)
 985                                 if (table->table [i])
 986                                         add_cprop_bb (cfg, table->table [i], bblist);
 987                 }
 988
 989                 /* Handle COMPARE+BRCOND pairs */
 990                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
 991                         if (c0) {
 992                                 g_assert (c0->opcode == OP_ICONST);
 993
 994                                 if (c0->inst_c0)
 995                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
 996                                 else
 997                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
 998                         }
 999                         else {
1000                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1001                         }
1002
1003                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1004                 }
1005         } else if (ins->opcode == OP_BR) {
1006                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1007         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1008                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1009                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1010                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1011                         if (ins->inst_false_bb)
1012                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1013         } else {
1014                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1015                         if (ins->inst_false_bb)
1016                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1017                 }
1018         }
1019 }
1020
1021 /**
1022  * fold_ins:
1023  *
1024  *   Replace INS with its constant value, if it exists
1025  */
1026 static void
1027 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1028 {
1029         const char *spec = INS_INFO (ins->opcode);
1030         int opcode2;
1031         int num_sregs = mono_inst_get_num_src_registers (ins);
1032
1033         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1034                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1035                         /* Perform constant folding */
1036                         /* FIXME: */
1037                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1038                         ins->opcode = OP_ICONST;
1039                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1040                         MONO_INST_NULLIFY_SREGS (ins);
1041                 } else if (num_sregs == 2 && carray [ins->sreg2]) {
1042                         /* Perform op->op_imm conversion */
1043                         opcode2 = mono_op_to_op_imm (ins->opcode);
1044                         if (opcode2 != -1) {
1045                                 ins->opcode = opcode2;
1046                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1047                                 ins->sreg2 = -1;
1048
1049                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1050                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1051                         }
1052                 } else {
1053                         /* FIXME: Handle 3 op insns */
1054                 }
1055
1056                 if (MONO_IS_JUMP_TABLE (ins)) {
1057                         int i;
1058                         MonoJumpInfoBBTable *table = MONO_JUMP_TABLE_FROM_INS (ins);
1059
1060                         if (!ins->next || ins->next->opcode != OP_PADD) {
1061                                 /* The PADD was optimized away */
1062                                 /* FIXME: handle this as well */
1063                                 return;
1064                         }
1065
1066                         g_assert (ins->next->opcode == OP_PADD);
1067                         g_assert (ins->next->sreg1 == ins->dreg);
1068                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1069
1070                         if (carray [ins->next->sreg2]) {
1071                                 /* Convert to a simple branch */
1072 #if SIZEOF_REGISTER == 8
1073                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1074 #else
1075                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1076 #endif
1077
1078                                 if (!((idx >= 0) && (idx < table->table_size))) {
1079                                         /* Out of range, eliminate the whole switch */
1080                                         for (i = 0; i < table->table_size; ++i) {
1081                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1082                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1083                                         }
1084
1085                                         NULLIFY_INS (ins);
1086                                         NULLIFY_INS (ins->next);
1087                                         NULLIFY_INS (ins->next->next);
1088                                         if (ins->next->next->next)
1089                                                 NULLIFY_INS (ins->next->next->next);
1090
1091                                         return;
1092                                 }
1093
1094                                 if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
1095                                         /* A one-way switch which got optimized away */
1096                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1097                                                 printf ("\tNo cfold on ");
1098                                                 mono_print_ins (ins);
1099                                         }
1100                                         return;
1101                                 }
1102
1103                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1104                                         printf ("\tcfold on ");
1105                                         mono_print_ins (ins);
1106                                 }
1107
1108                                 /* Unlink target bblocks */
1109                                 for (i = 0; i < table->table_size; ++i) {
1110                                         if (i != idx) {
1111                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1112                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1113                                         }
1114                                 }
1115
1116                                 /* Change the OP_BR_REG to a simple branch */
1117                                 ins->next->next->next->opcode = OP_BR;
1118                                 ins->next->next->next->inst_target_bb = table->table [idx];
1119                                 ins->next->next->next->sreg1 = -1;
1120
1121                                 /* Nullify the other instructions */
1122                                 NULLIFY_INS (ins);
1123                                 NULLIFY_INS (ins->next);
1124                                 NULLIFY_INS (ins->next->next);
1125                         }
1126                 }
1127         }
1128         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1129                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1130                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1131                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1132                         ins->opcode = OP_BR;
1133                         ins->inst_target_bb = ins->inst_true_bb;
1134                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1135                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1136                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1137                         ins->opcode = OP_BR;
1138                         ins->inst_target_bb = ins->inst_false_bb;
1139                 }
1140         }
1141 }
1142
1143 void
1144 mono_ssa_cprop (MonoCompile *cfg)
1145 {
1146         MonoInst **carray;
1147         MonoBasicBlock *bb;
1148         GList *bblock_list, *cvars;
1149         GList *tmp;
1150         int i;
1151         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1152
1153         carray = g_new0 (MonoInst*, cfg->next_vreg);
1154
1155         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1156                 mono_ssa_create_def_use (cfg);
1157
1158         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1159         cfg->bb_entry->flags |= BB_REACHABLE;
1160
1161         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1162
1163         for (i = 0; i < cfg->num_varinfo; i++) {
1164                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1165                 if (!info->def)
1166                         info->cpstate = 2;
1167         }
1168
1169         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1170                 /*
1171                  * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1172                  * that would still allow unreachable try's to be removed.
1173                  */
1174                 if (bb->region)
1175                         add_cprop_bb (cfg, bb, &bblock_list);
1176         }
1177
1178         cvars = NULL;
1179
1180         while (bblock_list) {
1181                 MonoInst *inst;
1182
1183                 bb = (MonoBasicBlock *)bblock_list->data;
1184
1185                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1186
1187                 g_assert (bb->flags &  BB_REACHABLE);
1188
1189                 /*
1190                  * Some bblocks are linked to 2 others even through they fall through to the
1191                  * next bblock.
1192                  */
1193                 if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
1194                         for (i = 0; i < bb->out_count; ++i)
1195                                 add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
1196                 }
1197
1198                 if (cfg->verbose_level > 1)
1199                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1200
1201                 for (inst = bb->code; inst; inst = inst->next) {
1202                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1203                 }
1204
1205                 while (cvars) {
1206                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1207                         cvars = g_list_delete_link (cvars, cvars);
1208
1209                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1210                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1211                                 if (!(ui->bb->flags & BB_REACHABLE))
1212                                         continue;
1213                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1214                         }
1215                 }
1216         }
1217
1218         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1219                 MonoInst *inst;
1220                 for (inst = bb->code; inst; inst = inst->next) {
1221                         fold_ins (cfg, bb, inst, carray);
1222                 }
1223         }
1224
1225         g_free (carray);
1226
1227         cfg->comp_done |= MONO_COMP_REACHABILITY;
1228
1229         /* fixme: we should update usage infos during cprop, instead of computing it again */
1230         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1231         for (i = 0; i < cfg->num_varinfo; i++) {
1232                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1233                 info->def = NULL;
1234                 info->uses = NULL;
1235         }
1236 }
1237
1238 static inline void
1239 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1240 {
1241         GList *tmp;
1242
1243         *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1244
1245         for (tmp = use->uses; tmp; tmp = tmp->next) {
1246                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1247                 if (ui->inst == var->def) {
1248                         /* from the mempool */
1249                         use->uses = g_list_remove_link (use->uses, tmp);
1250                         break;
1251                 }
1252         }
1253 }
1254
1255 void
1256 mono_ssa_deadce (MonoCompile *cfg)
1257 {
1258         int i;
1259         GList *work_list;
1260
1261         g_assert (cfg->comp_done & MONO_COMP_SSA);
1262
1263         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1264
1265         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1266                 mono_ssa_create_def_use (cfg);
1267
1268         mono_ssa_copyprop (cfg);
1269
1270         work_list = NULL;
1271         for (i = 0; i < cfg->num_varinfo; i++) {
1272                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1273                 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1274         }
1275
1276         while (work_list) {
1277                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1278                 work_list = g_list_remove_link (work_list, work_list);
1279
1280                 /*
1281                  * The second part of the condition happens often when PHI nodes have their dreg
1282                  * as one of their arguments due to the fact that we use the original vars.
1283                  */
1284                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1285                         MonoInst *def = info->def;
1286
1287                         /* Eliminating FMOVE could screw up the fp stack */
1288                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1289                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1290                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1291                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1292                                 def->opcode = OP_NOP;
1293                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1294                                 info->reg = -1;
1295                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1296                                 def->opcode = OP_NOP;
1297                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1298                                 info->reg = -1;
1299                         } else if (MONO_IS_PHI (def)) {
1300                                 int j;
1301                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1302                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1303                                         add_to_dce_worklist (cfg, info, u, &work_list);
1304                                 }
1305                                 def->opcode = OP_NOP;
1306                                 def->dreg = def->sreg1 = def->sreg2 = -1;
1307                                 info->reg = -1;
1308                         }
1309                         else if (def->opcode == OP_NOP) {
1310                         }
1311                         //else
1312                         //mono_print_ins (def);
1313                 }
1314
1315         }
1316 }
1317
1318 #if 0
1319 void
1320 mono_ssa_strength_reduction (MonoCompile *cfg)
1321 {
1322         MonoBasicBlock *bb;
1323         int i;
1324
1325         g_assert (cfg->comp_done & MONO_COMP_SSA);
1326         g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1327         g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1328
1329         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1330                 GList *lp = bb->loop_blocks;
1331
1332                 if (lp) {
1333                         MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1334
1335                         /* we only consider loops with 2 in bblocks */
1336                         if (!h->in_count == 2)
1337                                 continue;
1338
1339                         for (i = 0; i < cfg->num_varinfo; i++) {
1340                                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1341
1342                                 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1343                                     info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1344                                         MonoInst *v = info->def->inst_i1;
1345
1346
1347                                         printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1348                                 }
1349                         }
1350                 }
1351         }
1352 }
1353 #endif
1354
1355 #endif /* DISABLE_JIT */