mono/mini/ssa.c

   1 /*
   2  * ssa.c: Static single assign form support for the JIT compiler.
   3  *
   4  * Author:
   5  *    Dietmar Maurer (dietmar@ximian.com)
   6  *
   7  * (C) 2003 Ximian, Inc.
   8  * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
   9  */
  10 #include <config.h>
  11 #include <string.h>
  12 #include <mono/metadata/debug-helpers.h>
  13 #include <mono/metadata/mempool.h>
  14 #include <mono/metadata/mempool-internals.h>
  15
  16 #ifndef DISABLE_JIT
  17
  18 #include "mini.h"
  19 #ifdef HAVE_ALLOCA_H
  20 #include <alloca.h>
  21 #endif
  22
  23 #define CREATE_PRUNED_SSA
  24
  25 //#define DEBUG_SSA 1
  26
  27 #define NEW_PHI(cfg,dest,val) do {      \
  28         MONO_INST_NEW ((cfg), (dest), OP_PHI); \
  29         (dest)->inst_c0 = (val);                                                           \
  30         } while (0)
  31
  32 typedef struct {
  33         MonoBasicBlock *bb;
  34         MonoInst *inst;
  35 } MonoVarUsageInfo;
  36
  37 static void
  38 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
  39 {
  40         int i;
  41
  42         for (i = 0; i < bb->out_count; i++) {
  43                 if (bb->out_bb [i] == target) {
  44                         bb->out_bb [i] = bb->out_bb [--bb->out_count];
  45                         break;
  46                 }
  47         }
  48         for (i = 0; i < target->in_count; i++) {
  49                 if (target->in_bb [i] == bb) {
  50                         target->in_bb [i] = target->in_bb [--target->in_count];
  51                         break;
  52
  53                 }
  54         }
  55 }
  56
  57 static void
  58 unlink_unused_bblocks (MonoCompile *cfg)
  59 {
  60         int i, j;
  61         MonoBasicBlock *bb;
  62
  63         g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
  64
  65         if (G_UNLIKELY (cfg->verbose_level > 1))
  66                 printf ("\nUNLINK UNUSED BBLOCKS:\n");
  67
  68         for (bb = cfg->bb_entry; bb && bb->next_bb;) {
  69                 if (!(bb->next_bb->flags & BB_REACHABLE)) {
  70                         bb->next_bb = bb->next_bb->next_bb;
  71                 } else
  72                         bb = bb->next_bb;
  73         }
  74
  75         for (i = 1; i < cfg->num_bblocks; i++) {
  76                 bb = cfg->bblocks [i];
  77
  78                 if (!(bb->flags & BB_REACHABLE)) {
  79                         for (j = 0; j < bb->in_count; j++) {
  80                                 unlink_target (bb->in_bb [j], bb);
  81                         }
  82                         for (j = 0; j < bb->out_count; j++) {
  83                                 unlink_target (bb, bb->out_bb [j]);
  84                         }
  85                         if (G_UNLIKELY (cfg->verbose_level > 1))
  86                                 printf ("\tUnlinked BB%d\n", bb->block_num);
  87                 }
  88
  89         }
  90 }
  91
  92 /**
  93  * remove_bb_from_phis:
  94  *
  95  *   Remove BB from the PHI statements in TARGET.
  96  */
  97 static void
  98 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
  99 {
 100         MonoInst *ins;
 101         int i, j;
 102
 103         for (i = 0; i < target->in_count; i++) {
 104                 if (target->in_bb [i] == bb) {
 105                         break;
 106                 }
 107         }
 108         g_assert (i < target->in_count);
 109
 110         for (ins = target->code; ins; ins = ins->next) {
 111                 if (MONO_IS_PHI (ins)) {
 112                         for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
 113                                 ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
 114                         ins->inst_phi_args [0] --;
 115                 }
 116                 else
 117                         break;
 118         }
 119 }
 120
 121 static inline int
 122 op_phi_to_move (int opcode)
 123 {
 124         switch (opcode) {
 125         case OP_PHI:
 126                 return OP_MOVE;
 127         case OP_FPHI:
 128                 return OP_FMOVE;
 129         case OP_VPHI:
 130                 return OP_VMOVE;
 131         case OP_XPHI:
 132                 return OP_XMOVE;
 133         default:
 134                 g_assert_not_reached ();
 135         }
 136
 137         return -1;
 138 }
 139
 140 static inline void
 141 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
 142 {
 143         MonoMethodVar *info;
 144         MonoVarUsageInfo *ui = (MonoVarUsageInfo *)mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
 145
 146         info = MONO_VARINFO (cfg, var->inst_c0);
 147
 148         ui->bb = bb;
 149         ui->inst = ins;
 150         info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
 151 }
 152
 153 typedef struct {
 154         MonoInst *var;
 155         int idx;
 156 } RenameInfo;
 157
 158 /**
 159  * mono_ssa_rename_vars:
 160  *
 161  *  Implement renaming of SSA variables. Also compute def-use information in parallel.
 162  * @stack_history points to an area of memory which can be used for storing changes
 163  * made to the stack, so they can be reverted later.
 164  */
 165 static void
 166 mono_ssa_rename_vars (MonoCompile *cfg, int max_vars, MonoBasicBlock *bb, gboolean *originals_used, MonoInst **stack,   guint32 *lvreg_stack, gboolean *lvreg_defined, RenameInfo *stack_history, int stack_history_size)
 167 {
 168         MonoInst *ins, *new_var;
 169         int i, j, idx;
 170         GSList *tmp;
 171         int stack_history_len = 0;
 172
 173         if (cfg->verbose_level >= 4)
 174                 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
 175
 176         /* First pass: Create new vars */
 177         for (ins = bb->code; ins; ins = ins->next) {
 178                 const char *spec = INS_INFO (ins->opcode);
 179                 int num_sregs;
 180                 int sregs [MONO_MAX_SRC_REGS];
 181
 182 #ifdef DEBUG_SSA
 183                 printf ("\tProcessing "); mono_print_ins (ins);
 184 #endif
 185                 if (ins->opcode == OP_NOP)
 186                         continue;
 187
 188                 /* SREGs */
 189                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 190                 for (i = 0; i < num_sregs; ++i) {
 191                         if (spec [MONO_INST_SRC1 + i] != ' ') {
 192                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 193                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 194                                         int idx = var->inst_c0;
 195                                         if (stack [idx]) {
 196                                                 if (var->opcode != OP_ARG)
 197                                                         g_assert (stack [idx]);
 198                                                 sregs [i] = stack [idx]->dreg;
 199                                                 record_use (cfg, stack [idx], bb, ins);
 200                                         }
 201                                         else
 202                                                 record_use (cfg, var, bb, ins);
 203                                 }
 204                                 else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
 205                                         sregs [i] = lvreg_stack [sregs [i]];
 206                         }
 207                 }
 208                 mono_inst_set_src_registers (ins, sregs);
 209
 210                 if (MONO_IS_STORE_MEMBASE (ins)) {
 211                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 212                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 213                                 int idx = var->inst_c0;
 214                                 if (stack [idx]) {
 215                                         if (var->opcode != OP_ARG)
 216                                                 g_assert (stack [idx]);
 217                                         ins->dreg = stack [idx]->dreg;
 218                                         record_use (cfg, stack [idx], bb, ins);
 219                                 }
 220                                 else
 221                                         record_use (cfg, var, bb, ins);
 222                         }
 223                         else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
 224                                 ins->dreg = lvreg_stack [ins->dreg];
 225                 }
 226
 227                 /* DREG */
 228                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 229                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 230                         MonoMethodVar *info;
 231
 232                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 233                                 idx = var->inst_c0;
 234                                 g_assert (idx < max_vars);
 235
 236                                 if (var->opcode == OP_ARG)
 237                                         originals_used [idx] = TRUE;
 238
 239                                 /* FIXME: */
 240                                 g_assert (stack_history_len < stack_history_size);
 241                                 stack_history [stack_history_len].var = stack [idx];
 242                                 stack_history [stack_history_len].idx = idx;
 243                                 stack_history_len ++;
 244
 245                                 if (originals_used [idx]) {
 246                                         new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
 247                                         new_var->flags = var->flags;
 248                                         MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
 249
 250                                         if (cfg->verbose_level >= 4)
 251                                                 printf ("  R%d -> R%d\n", var->dreg, new_var->dreg);
 252
 253                                         stack [idx] = new_var;
 254
 255                                         ins->dreg = new_var->dreg;
 256                                         var = new_var;
 257                                 }
 258                                 else {
 259                                         stack [idx] = var;
 260                                         originals_used [idx] = TRUE;
 261                                 }
 262
 263                                 info = MONO_VARINFO (cfg, var->inst_c0);
 264                                 info->def = ins;
 265                                 info->def_bb = bb;
 266                         }
 267                         else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
 268                                 /* Perform renaming for local vregs */
 269                                 lvreg_stack [ins->dreg] = vreg_is_ref (cfg, ins->dreg) ? mono_alloc_ireg_ref (cfg) : mono_alloc_preg (cfg);
 270                                 ins->dreg = lvreg_stack [ins->dreg];
 271                         }
 272                         else
 273                                 lvreg_defined [ins->dreg] = TRUE;
 274                 }
 275
 276 #ifdef DEBUG_SSA
 277                 printf ("\tAfter processing "); mono_print_ins (ins);
 278 #endif
 279
 280         }
 281
 282         /* Rename PHI arguments in succeeding bblocks */
 283         for (i = 0; i < bb->out_count; i++) {
 284                 MonoBasicBlock *n = bb->out_bb [i];
 285
 286                 for (j = 0; j < n->in_count; j++)
 287                         if (n->in_bb [j] == bb)
 288                                 break;
 289
 290                 for (ins = n->code; ins; ins = ins->next) {
 291                         if (MONO_IS_PHI (ins)) {
 292                                 idx = ins->inst_c0;
 293                                 if (stack [idx])
 294                                         new_var = stack [idx];
 295                                 else
 296                                         new_var = cfg->varinfo [idx];
 297 #ifdef DEBUG_SSA
 298                                 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
 299 #endif
 300                                 ins->inst_phi_args [j + 1] = new_var->dreg;
 301                                 record_use (cfg,  new_var, n, ins);
 302                                 if (G_UNLIKELY (cfg->verbose_level >= 4))
 303                                         printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
 304                         }
 305                         else
 306                                 /* The phi nodes are at the beginning of the bblock */
 307                                 break;
 308                 }
 309         }
 310
 311         if (bb->dominated) {
 312                 for (tmp = bb->dominated; tmp; tmp = tmp->next) {
 313                         mono_ssa_rename_vars (cfg, max_vars, (MonoBasicBlock *)tmp->data, originals_used, stack, lvreg_stack, lvreg_defined, stack_history + stack_history_len, stack_history_size - stack_history_len);
 314                 }
 315         }
 316
 317         /* Restore stack */
 318         for (i = stack_history_len - 1; i >= 0; i--) {
 319                 stack [stack_history [i].idx] = stack_history [i].var;
 320         }
 321
 322         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 323 }
 324
 325 void
 326 mono_ssa_compute (MonoCompile *cfg)
 327 {
 328         int i, j, idx, bitsize;
 329         MonoBitSet *set;
 330         MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
 331         MonoInst *ins, **stack;
 332         guint8 *buf, *buf_start;
 333         RenameInfo *stack_history;
 334         int stack_history_size;
 335         gboolean *originals;
 336         guint32 *lvreg_stack;
 337         gboolean *lvreg_defined;
 338
 339         g_assert (!(cfg->comp_done & MONO_COMP_SSA));
 340
 341         g_assert (!cfg->disable_ssa);
 342
 343         if (cfg->verbose_level >= 4)
 344                 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
 345
 346 #ifdef CREATE_PRUNED_SSA
 347         /* we need liveness for pruned SSA */
 348         if (!(cfg->comp_done & MONO_COMP_LIVENESS))
 349                 mono_analyze_liveness (cfg);
 350 #endif
 351
 352         mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
 353
 354         bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
 355         buf = buf_start = (guint8 *)g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
 356
 357         for (i = 0; i < cfg->num_varinfo; ++i) {
 358                 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
 359                 buf += bitsize;
 360                 vinfo [i].idx = i;
 361                 /* implicit reference at start */
 362                 if (cfg->varinfo [i]->opcode == OP_ARG)
 363                         mono_bitset_set_fast (vinfo [i].def_in, 0);
 364         }
 365
 366         for (i = 0; i < cfg->num_bblocks; ++i) {
 367                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 368                         if (ins->opcode == OP_NOP)
 369                                 continue;
 370
 371                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 372                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 373                         }
 374                 }
 375         }
 376
 377         /* insert phi functions */
 378         for (i = 0; i < cfg->num_varinfo; ++i) {
 379                 MonoInst *var = cfg->varinfo [i];
 380
 381 #if SIZEOF_REGISTER == 4
 382                 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
 383                         continue;
 384 #endif
 385                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 386                         continue;
 387
 388                 /* Most variables have only one definition */
 389                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 390                         continue;
 391
 392                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 393
 394                 if (cfg->verbose_level >= 4) {
 395                         if (mono_bitset_count (set) > 0) {
 396                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 397                                 mono_blockset_print (cfg, set, "", -1);
 398                         }
 399                 }
 400
 401                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 402                         MonoBasicBlock *bb = cfg->bblocks [idx];
 403
 404                         /* fixme: create pruned SSA? we would need liveness information for that */
 405
 406                         if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
 407                                 continue;
 408
 409                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 410                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 411                                 continue;
 412                         }
 413
 414                         NEW_PHI (cfg, ins, i);
 415
 416                         switch (var->type) {
 417                         case STACK_I4:
 418                         case STACK_I8:
 419                         case STACK_PTR:
 420                         case STACK_MP:
 421                         case STACK_OBJ:
 422                                 ins->opcode = OP_PHI;
 423                                 break;
 424                         case STACK_R8:
 425                                 ins->opcode = OP_FPHI;
 426                                 break;
 427                         case STACK_VTYPE:
 428                                 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
 429                                 break;
 430                         }
 431
 432                         if (var->inst_vtype->byref)
 433                                 ins->klass = mono_defaults.int_class;
 434                         else
 435                                 ins->klass = var->klass;
 436
 437                         ins->inst_phi_args = (int *)mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 438                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 439
 440                         /* For debugging */
 441                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 442                                 ins->inst_phi_args [j + 1] = -1;
 443
 444                         ins->dreg = cfg->varinfo [i]->dreg;
 445
 446                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 447
 448 #ifdef DEBUG_SSA
 449                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 450 #endif
 451                 }
 452         }
 453
 454         /* free the stuff */
 455         g_free (vinfo);
 456         g_free (buf_start);
 457
 458         /* Renaming phase */
 459
 460         stack = (MonoInst **)alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 461         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 462
 463         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 464         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 465         stack_history_size = 10240;
 466         stack_history = g_new (RenameInfo, stack_history_size);
 467         originals = g_new0 (gboolean, cfg->num_varinfo);
 468         mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 469         g_free (stack_history);
 470         g_free (originals);
 471         g_free (lvreg_stack);
 472         g_free (lvreg_defined);
 473
 474         if (cfg->verbose_level >= 4)
 475                 printf ("\nEND COMPUTE SSA.\n\n");
 476
 477         cfg->comp_done |= MONO_COMP_SSA;
 478 }
 479
 480 /*
 481  * mono_ssa_remove_gsharedvt:
 482  *
 483  *   Same as mono_ssa_remove, but only remove phi nodes for gsharedvt variables.
 484  */
 485 void
 486 mono_ssa_remove_gsharedvt (MonoCompile *cfg)
 487 {
 488         MonoInst *ins, *var, *move;
 489         int i, j, first;
 490
 491         /*
 492          * When compiling gsharedvt code, we need to get rid of the VPHI instructions,
 493          * since they cannot be handled later in the llvm backend.
 494          */
 495         g_assert (cfg->comp_done & MONO_COMP_SSA);
 496
 497         for (i = 0; i < cfg->num_bblocks; ++i) {
 498                 MonoBasicBlock *bb = cfg->bblocks [i];
 499
 500                 if (cfg->verbose_level >= 4)
 501                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 502
 503                 for (ins = bb->code; ins; ins = ins->next) {
 504                         if (!(MONO_IS_PHI (ins) && ins->opcode == OP_VPHI && mini_is_gsharedvt_variable_type (&ins->klass->byval_arg)))
 505                                 continue;
 506
 507                         g_assert (ins->inst_phi_args [0] == bb->in_count);
 508                         var = get_vreg_to_inst (cfg, ins->dreg);
 509
 510                         /* Check for PHI nodes where all the inputs are the same */
 511                         first = ins->inst_phi_args [1];
 512
 513                         for (j = 1; j < bb->in_count; ++j)
 514                                 if (first != ins->inst_phi_args [j + 1])
 515                                         break;
 516
 517                         if ((bb->in_count > 1) && (j == bb->in_count)) {
 518                                 ins->opcode = op_phi_to_move (ins->opcode);
 519                                 if (ins->opcode == OP_VMOVE)
 520                                         g_assert (ins->klass);
 521                                 ins->sreg1 = first;
 522                         } else {
 523                                 for (j = 0; j < bb->in_count; j++) {
 524                                         MonoBasicBlock *pred = bb->in_bb [j];
 525                                         int sreg = ins->inst_phi_args [j + 1];
 526
 527                                         if (cfg->verbose_level >= 4)
 528                                                 printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 529                                         if (var->dreg != sreg) {
 530                                                 MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 531                                                 if (move->opcode == OP_VMOVE) {
 532                                                         g_assert (ins->klass);
 533                                                         move->klass = ins->klass;
 534                                                 }
 535                                                 move->dreg = var->dreg;
 536                                                 move->sreg1 = sreg;
 537                                                 mono_add_ins_to_end (pred, move);
 538                                         }
 539                                 }
 540
 541                                 NULLIFY_INS (ins);
 542                         }
 543                 }
 544         }
 545 }
 546
 547 void
 548 mono_ssa_remove (MonoCompile *cfg)
 549 {
 550         MonoInst *ins, *var, *move;
 551         int bbindex, i, j, first;
 552
 553         g_assert (cfg->comp_done & MONO_COMP_SSA);
 554
 555         for (i = 0; i < cfg->num_bblocks; ++i) {
 556                 MonoBasicBlock *bb = cfg->bblocks [i];
 557
 558                 if (cfg->verbose_level >= 4)
 559                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 560
 561                 for (ins = bb->code; ins; ins = ins->next) {
 562                         if (MONO_IS_PHI (ins)) {
 563                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 564                                 var = get_vreg_to_inst (cfg, ins->dreg);
 565
 566                                 /* Check for PHI nodes where all the inputs are the same */
 567                                 first = ins->inst_phi_args [1];
 568
 569                                 for (j = 1; j < bb->in_count; ++j)
 570                                         if (first != ins->inst_phi_args [j + 1])
 571                                                 break;
 572
 573                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 574                                         ins->opcode = op_phi_to_move (ins->opcode);
 575                                         if (ins->opcode == OP_VMOVE)
 576                                                 g_assert (ins->klass);
 577                                         ins->sreg1 = first;
 578                                 } else {
 579                                         for (j = 0; j < bb->in_count; j++) {
 580                                                 MonoBasicBlock *pred = bb->in_bb [j];
 581                                                 int sreg = ins->inst_phi_args [j + 1];
 582
 583                                                 if (cfg->verbose_level >= 4)
 584                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 585                                                 if (var->dreg != sreg) {
 586                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 587                                                         if (move->opcode == OP_VMOVE) {
 588                                                                 g_assert (ins->klass);
 589                                                                 move->klass = ins->klass;
 590                                                         }
 591                                                         move->dreg = var->dreg;
 592                                                         move->sreg1 = sreg;
 593                                                         mono_add_ins_to_end (pred, move);
 594                                                 }
 595                                         }
 596
 597                                         NULLIFY_INS (ins);
 598                                 }
 599                         }
 600                 }
 601         }
 602
 603         if (cfg->verbose_level >= 4) {
 604                 for (i = 0; i < cfg->num_bblocks; ++i) {
 605                         MonoBasicBlock *bb = cfg->bblocks [i];
 606
 607                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 608                 }
 609         }
 610
 611         /*
 612          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 613          * the variables if possible. Since the newly introduced SSA variables don't
 614          * have overlapping live ranges (because we don't do agressive optimization), we
 615          * can coalesce them into the original variable.
 616          */
 617
 618         for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
 619                 MonoBasicBlock *bb = cfg->bblocks [bbindex];
 620
 621                 for (ins = bb->code; ins; ins = ins->next) {
 622                         const char *spec = INS_INFO (ins->opcode);
 623                         int num_sregs;
 624                         int sregs [MONO_MAX_SRC_REGS];
 625
 626                         if (ins->opcode == OP_NOP)
 627                                 continue;
 628
 629                         if (spec [MONO_INST_DEST] != ' ') {
 630                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 631
 632                                 if (var) {
 633                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 634
 635                                         /*
 636                                          * The third condition avoids coalescing with variables eliminated
 637                                          * during deadce.
 638                                          */
 639                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 640                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 641                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 642                                         }
 643                                 }
 644                         }
 645
 646                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 647                         for (i = 0; i < num_sregs; ++i) {
 648                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 649
 650                                 if (var) {
 651                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 652
 653                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 654                                                 printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
 655                                                 sregs [i] = cfg->varinfo [vmv->reg]->dreg;
 656                                         }
 657                                 }
 658                         }
 659                         mono_inst_set_src_registers (ins, sregs);
 660                 }
 661         }
 662
 663         for (i = 0; i < cfg->num_varinfo; ++i) {
 664                 MONO_VARINFO (cfg, i)->reg = -1;
 665         }
 666
 667         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 668                 unlink_unused_bblocks (cfg);
 669
 670         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 671
 672         cfg->comp_done &= ~MONO_COMP_SSA;
 673 }
 674
 675 static void
 676 mono_ssa_create_def_use (MonoCompile *cfg)
 677 {
 678         MonoBasicBlock *bb;
 679         MonoInst *ins;
 680         int i;
 681
 682         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 683
 684         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 685                 for (ins = bb->code; ins; ins = ins->next) {
 686                         const char *spec = INS_INFO (ins->opcode);
 687                         MonoMethodVar *info;
 688                         int num_sregs;
 689                         int sregs [MONO_MAX_SRC_REGS];
 690
 691                         if (ins->opcode == OP_NOP)
 692                                 continue;
 693
 694                         /* SREGs */
 695                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 696                         for (i = 0; i < num_sregs; ++i) {
 697                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 698                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 699                                         record_use (cfg, var, bb, ins);
 700                         }
 701
 702                         if (MONO_IS_STORE_MEMBASE (ins)) {
 703                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 704                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 705                                         record_use (cfg, var, bb, ins);
 706                         }
 707
 708                         if (MONO_IS_PHI (ins)) {
 709                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 710                                         g_assert (ins->inst_phi_args [i] != -1);
 711                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 712                                 }
 713                         }
 714
 715                         /* DREG */
 716                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 717                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 718
 719                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 720                                         info = MONO_VARINFO (cfg, var->inst_c0);
 721                                         info->def = ins;
 722                                         info->def_bb = bb;
 723                                 }
 724                         }
 725                 }
 726         }
 727
 728         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 729 }
 730
 731 static void
 732 mono_ssa_copyprop (MonoCompile *cfg)
 733 {
 734         int i, index;
 735         GList *l;
 736
 737         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 738
 739         for (index = 0; index < cfg->num_varinfo; ++index) {
 740                 MonoInst *var = cfg->varinfo [index];
 741                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 742
 743                 if (info->def && (MONO_IS_MOVE (info->def))) {
 744                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 745
 746                         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))) {
 747                                 /* Rewrite all uses of var to be uses of var2 */
 748                                 int dreg = var->dreg;
 749                                 int sreg1 = var2->dreg;
 750
 751                                 l = info->uses;
 752                                 while (l) {
 753                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 754                                         MonoInst *ins = u->inst;
 755                                         GList *next = l->next;
 756                                         int num_sregs;
 757                                         int sregs [MONO_MAX_SRC_REGS];
 758
 759                                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 760                                         for (i = 0; i < num_sregs; ++i) {
 761                                                 if (sregs [i] == dreg)
 762                                                         break;
 763                                         }
 764                                         if (i < num_sregs) {
 765                                                 g_assert (sregs [i] == dreg);
 766                                                 sregs [i] = sreg1;
 767                                                 mono_inst_set_src_registers (ins, sregs);
 768                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 769                                                 ins->dreg = sreg1;
 770                                         } else if (MONO_IS_PHI (ins)) {
 771                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 772                                                         int sreg = ins->inst_phi_args [i];
 773                                                         if (sreg == var->dreg)
 774                                                                 break;
 775                                                 }
 776                                                 g_assert (i > 0);
 777                                                 ins->inst_phi_args [i] = sreg1;
 778                                         }
 779                                         else
 780                                                 g_assert_not_reached ();
 781
 782                                         record_use (cfg, var2, u->bb, ins);
 783
 784                                         l = next;
 785                                 }
 786
 787                                 info->uses = NULL;
 788                         }
 789                 }
 790         }
 791
 792         if (cfg->verbose_level >= 4) {
 793                 MonoBasicBlock *bb;
 794
 795                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 796                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 797         }
 798 }
 799
 800 static int
 801 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 802 {
 803         MonoInst *args [MONO_MAX_SRC_REGS];
 804         int rs [MONO_MAX_SRC_REGS];
 805         MonoInst *c0;
 806         gboolean const_args = TRUE;
 807         const char *spec = INS_INFO (ins->opcode);
 808         int num_sregs, i;
 809         int sregs [MONO_MAX_SRC_REGS];
 810
 811         /* Short-circuit this */
 812         if (ins->opcode == OP_ICONST) {
 813                 *res = ins;
 814                 return 1;
 815         }
 816
 817         if (ins->opcode == OP_NOP)
 818                 return 2;
 819
 820         num_sregs = mono_inst_get_src_registers (ins, sregs);
 821         for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
 822                 args [i] = NULL;
 823         for (i = 0; i < num_sregs; ++i) {
 824                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 825
 826                 rs [i] = 2;
 827                 args [i] = carray [sregs [i]];
 828                 if (args [i])
 829                         rs [i] = 1;
 830                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 831                         rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 832                 if (rs [i] != 1)
 833                         const_args = FALSE;
 834         }
 835
 836         c0 = NULL;
 837
 838         if (num_sregs > 0 && const_args) {
 839                 g_assert (num_sregs <= 2);
 840                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 841                         // Cached value
 842                         *res = carray [ins->dreg];
 843                         return 1;
 844                 }
 845                 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
 846                 if (c0) {
 847                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 848                                 printf ("\t cfold -> ");
 849                                 mono_print_ins (c0);
 850                         }
 851                         *res = c0;
 852                         return 1;
 853                 }
 854                 else
 855                         /* Can't cfold this ins */
 856                         return 2;
 857         }
 858
 859         if (num_sregs == 0)
 860                 return 2;
 861         for (i = 0; i < num_sregs; ++i) {
 862                 if (rs [i] == 2)
 863                         return 2;
 864         }
 865         return 0;
 866 }
 867
 868 static inline void
 869 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 870 {
 871         if (info->cpstate >= state)
 872                 return;
 873
 874         info->cpstate = state;
 875
 876         if (G_UNLIKELY (cfg->verbose_level > 1))
 877                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 878
 879         if (state == 1)
 880                 g_assert (c0);
 881
 882         carray [cfg->varinfo [info->idx]->dreg] = c0;
 883
 884         if (!g_list_find (*cvars, info)) {
 885                 *cvars = g_list_prepend (*cvars, info);
 886         }
 887 }
 888
 889 static inline void
 890 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 891 {
 892         if (G_UNLIKELY (cfg->verbose_level > 1))
 893                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 894
 895     if (!(bb->flags &  BB_REACHABLE)) {
 896             bb->flags |= BB_REACHABLE;
 897                 *bblist = g_list_prepend (*bblist, bb);
 898         }
 899 }
 900
 901 static void
 902 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 903 {
 904         const char *spec = INS_INFO (ins->opcode);
 905
 906         if (ins->opcode == OP_NOP)
 907                 return;
 908
 909         if (cfg->verbose_level > 1)
 910                 mono_print_ins (ins);
 911
 912         /* FIXME: Support longs/floats */
 913         /* FIXME: Work on vregs as well */
 914
 915         if (MONO_IS_PHI (ins)) {
 916                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 917                 MonoInst *c0 = NULL;
 918                 int j;
 919
 920                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 921                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 922                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 923                         MonoInst *src = mv->def;
 924
 925                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 926                                 continue;
 927
 928                         if (!mv->def || !src || mv->cpstate == 2) {
 929                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 930                                 break;
 931                         }
 932
 933                         if (mv->cpstate == 0)
 934                                 continue;
 935
 936                         g_assert (carray [var->dreg]);
 937
 938                         if (!c0)
 939                                 c0 = carray [var->dreg];
 940
 941                         /* FIXME: */
 942                         if (c0->opcode != OP_ICONST) {
 943                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 944                                 break;
 945                         }
 946
 947                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 948                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 949                                 break;
 950                         }
 951                 }
 952
 953                 if (c0 && info->cpstate < 1) {
 954                         change_varstate (cfg, cvars, info, 1, c0, carray);
 955
 956                         g_assert (c0->opcode == OP_ICONST);
 957                 }
 958         }
 959         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 960                 MonoInst *var, *c0;
 961                 int state;
 962
 963                 if (spec [MONO_INST_DEST] !=  ' ')
 964                         var = get_vreg_to_inst (cfg, ins->dreg);
 965                 else
 966                         var = NULL;
 967
 968                 c0 = NULL;
 969                 state = evaluate_ins (cfg, ins, &c0, carray);
 970
 971                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 972                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 973
 974                         if (info->cpstate < 2) {
 975                                 if (state == 1)
 976                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 977                                 else if (state == 2)
 978                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 979                         }
 980                 }
 981                 else if (!var && (ins->dreg != -1)) {
 982                         /*
 983                          * We don't record def-use information for local vregs since it would be
 984                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 985                          * the same bblock, so they will be examined after the definition.
 986                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 987                          */
 988                         if (c0) {
 989                                 carray [ins->dreg] = c0;
 990                         } else {
 991                                 if (carray [ins->dreg]) {
 992                                         /*
 993                                          * The state of the vreg changed from constant to non-constant
 994                                          * -> need to rescan the whole bblock.
 995                                          */
 996                                         carray [ins->dreg] = NULL;
 997                                         /* FIXME: Speed this up */
 998
 999                                         if (!g_list_find (*bblist, bb))
1000                                                 *bblist = g_list_prepend (*bblist, bb);
1001                                 }
1002                         }
1003                 }
1004
1005                 if (MONO_IS_JUMP_TABLE (ins)) {
1006                         int i;
1007                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1008
1009                         if (!ins->next || ins->next->opcode != OP_PADD) {
1010                                 /* The PADD was optimized away */
1011                                 /* FIXME: handle this as well */
1012                                 for (i = 0; i < table->table_size; i++)
1013                                         if (table->table [i])
1014                                                 add_cprop_bb (cfg, table->table [i], bblist);
1015                                 return;
1016                         }
1017
1018                         g_assert (ins->next->opcode == OP_PADD);
1019                         g_assert (ins->next->sreg1 == ins->dreg);
1020
1021                         if (carray [ins->next->sreg2]) {
1022 #if SIZEOF_REGISTER == 8
1023                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1024 #else
1025                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1026 #endif
1027                                 if ((idx < 0) || (idx >= table->table_size))
1028                                         /* Out-of-range, no branch is executed */
1029                                         return;
1030                                 else
1031                                         if (table->table [idx])
1032                                                 add_cprop_bb (cfg, table->table [idx], bblist);
1033                         }
1034                         else {
1035                                 for (i = 0; i < table->table_size; i++)
1036                                         if (table->table [i])
1037                                                 add_cprop_bb (cfg, table->table [i], bblist);
1038                         }
1039                 }
1040
1041                 if (ins->opcode == OP_SWITCH) {
1042                         int i;
1043                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)ins->inst_p0;
1044
1045                         for (i = 0; i < table->table_size; i++)
1046                                 if (table->table [i])
1047                                         add_cprop_bb (cfg, table->table [i], bblist);
1048                 }
1049
1050                 /* Handle COMPARE+BRCOND pairs */
1051                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
1052                         if (c0) {
1053                                 g_assert (c0->opcode == OP_ICONST);
1054
1055                                 if (c0->inst_c0)
1056                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
1057                                 else
1058                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
1059                         }
1060                         else {
1061                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1062                         }
1063
1064                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1065                 }
1066         } else if (ins->opcode == OP_BR) {
1067                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1068         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1069                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1070                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1071                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1072                         if (ins->inst_false_bb)
1073                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1074         } else {
1075                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1076                         if (ins->inst_false_bb)
1077                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1078                 }
1079         }
1080 }
1081
1082 /**
1083  * fold_ins:
1084  *
1085  *   Replace INS with its constant value, if it exists
1086  */
1087 static void
1088 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1089 {
1090         const char *spec = INS_INFO (ins->opcode);
1091         int opcode2;
1092         int num_sregs = mono_inst_get_num_src_registers (ins);
1093
1094         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1095                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1096                         /* Perform constant folding */
1097                         /* FIXME: */
1098                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1099                         ins->opcode = OP_ICONST;
1100                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1101                         MONO_INST_NULLIFY_SREGS (ins);
1102                 } else if (num_sregs == 2 && carray [ins->sreg2]) {
1103                         /* Perform op->op_imm conversion */
1104                         opcode2 = mono_op_to_op_imm (ins->opcode);
1105                         if (opcode2 != -1) {
1106                                 ins->opcode = opcode2;
1107                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1108                                 ins->sreg2 = -1;
1109
1110                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1111                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1112                         }
1113                 } else {
1114                         /* FIXME: Handle 3 op insns */
1115                 }
1116
1117                 if (MONO_IS_JUMP_TABLE (ins)) {
1118                         int i;
1119                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1120
1121                         if (!ins->next || ins->next->opcode != OP_PADD) {
1122                                 /* The PADD was optimized away */
1123                                 /* FIXME: handle this as well */
1124                                 return;
1125                         }
1126
1127                         g_assert (ins->next->opcode == OP_PADD);
1128                         g_assert (ins->next->sreg1 == ins->dreg);
1129                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1130
1131                         if (carray [ins->next->sreg2]) {
1132                                 /* Convert to a simple branch */
1133 #if SIZEOF_REGISTER == 8
1134                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1135 #else
1136                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1137 #endif
1138
1139                                 if (!((idx >= 0) && (idx < table->table_size))) {
1140                                         /* Out of range, eliminate the whole switch */
1141                                         for (i = 0; i < table->table_size; ++i) {
1142                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1143                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1144                                         }
1145
1146                                         NULLIFY_INS (ins);
1147                                         NULLIFY_INS (ins->next);
1148                                         NULLIFY_INS (ins->next->next);
1149                                         if (ins->next->next->next)
1150                                                 NULLIFY_INS (ins->next->next->next);
1151
1152                                         return;
1153                                 }
1154
1155                                 if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
1156                                         /* A one-way switch which got optimized away */
1157                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1158                                                 printf ("\tNo cfold on ");
1159                                                 mono_print_ins (ins);
1160                                         }
1161                                         return;
1162                                 }
1163
1164                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1165                                         printf ("\tcfold on ");
1166                                         mono_print_ins (ins);
1167                                 }
1168
1169                                 /* Unlink target bblocks */
1170                                 for (i = 0; i < table->table_size; ++i) {
1171                                         if (table->table [i] != table->table [idx]) {
1172                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1173                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1174                                         }
1175                                 }
1176
1177                                 /* Change the OP_BR_REG to a simple branch */
1178                                 ins->next->next->next->opcode = OP_BR;
1179                                 ins->next->next->next->inst_target_bb = table->table [idx];
1180                                 ins->next->next->next->sreg1 = -1;
1181
1182                                 /* Nullify the other instructions */
1183                                 NULLIFY_INS (ins);
1184                                 NULLIFY_INS (ins->next);
1185                                 NULLIFY_INS (ins->next->next);
1186                         }
1187                 }
1188         }
1189         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1190                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1191                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1192                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1193                         ins->opcode = OP_BR;
1194                         ins->inst_target_bb = ins->inst_true_bb;
1195                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1196                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1197                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1198                         ins->opcode = OP_BR;
1199                         ins->inst_target_bb = ins->inst_false_bb;
1200                 }
1201         }
1202 }
1203
1204 void
1205 mono_ssa_cprop (MonoCompile *cfg)
1206 {
1207         MonoInst **carray;
1208         MonoBasicBlock *bb;
1209         GList *bblock_list, *cvars;
1210         GList *tmp;
1211         int i;
1212         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1213
1214         carray = g_new0 (MonoInst*, cfg->next_vreg);
1215
1216         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1217                 mono_ssa_create_def_use (cfg);
1218
1219         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1220         cfg->bb_entry->flags |= BB_REACHABLE;
1221
1222         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1223
1224         for (i = 0; i < cfg->num_varinfo; i++) {
1225                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1226                 if (!info->def)
1227                         info->cpstate = 2;
1228         }
1229
1230         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1231                 /*
1232                  * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1233                  * that would still allow unreachable try's to be removed.
1234                  */
1235                 if (bb->region)
1236                         add_cprop_bb (cfg, bb, &bblock_list);
1237         }
1238
1239         cvars = NULL;
1240
1241         while (bblock_list) {
1242                 MonoInst *inst;
1243
1244                 bb = (MonoBasicBlock *)bblock_list->data;
1245
1246                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1247
1248                 g_assert (bb->flags &  BB_REACHABLE);
1249
1250                 /*
1251                  * Some bblocks are linked to 2 others even through they fall through to the
1252                  * next bblock.
1253                  */
1254                 if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
1255                         for (i = 0; i < bb->out_count; ++i)
1256                                 add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
1257                 }
1258
1259                 if (cfg->verbose_level > 1)
1260                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1261
1262                 for (inst = bb->code; inst; inst = inst->next) {
1263                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1264                 }
1265
1266                 while (cvars) {
1267                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1268                         cvars = g_list_delete_link (cvars, cvars);
1269
1270                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1271                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1272                                 if (!(ui->bb->flags & BB_REACHABLE))
1273                                         continue;
1274                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1275                         }
1276                 }
1277         }
1278
1279         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1280                 MonoInst *inst;
1281                 for (inst = bb->code; inst; inst = inst->next) {
1282                         fold_ins (cfg, bb, inst, carray);
1283                 }
1284         }
1285
1286         g_free (carray);
1287
1288         cfg->comp_done |= MONO_COMP_REACHABILITY;
1289
1290         /* fixme: we should update usage infos during cprop, instead of computing it again */
1291         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1292         for (i = 0; i < cfg->num_varinfo; i++) {
1293                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1294                 info->def = NULL;
1295                 info->uses = NULL;
1296         }
1297 }
1298
1299 static inline void
1300 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1301 {
1302         GList *tmp;
1303
1304         *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1305
1306         for (tmp = use->uses; tmp; tmp = tmp->next) {
1307                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1308                 if (ui->inst == var->def) {
1309                         /* from the mempool */
1310                         use->uses = g_list_remove_link (use->uses, tmp);
1311                         break;
1312                 }
1313         }
1314 }
1315
1316 void
1317 mono_ssa_deadce (MonoCompile *cfg)
1318 {
1319         int i;
1320         GList *work_list;
1321
1322         g_assert (cfg->comp_done & MONO_COMP_SSA);
1323
1324         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1325
1326         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1327                 mono_ssa_create_def_use (cfg);
1328
1329         mono_ssa_copyprop (cfg);
1330
1331         work_list = NULL;
1332         for (i = 0; i < cfg->num_varinfo; i++) {
1333                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1334                 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1335         }
1336
1337         while (work_list) {
1338                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1339                 work_list = g_list_remove_link (work_list, work_list);
1340
1341                 /*
1342                  * The second part of the condition happens often when PHI nodes have their dreg
1343                  * as one of their arguments due to the fact that we use the original vars.
1344                  */
1345                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1346                         MonoInst *def = info->def;
1347
1348                         /* Eliminating FMOVE could screw up the fp stack */
1349                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1350                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1351                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1352                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1353                                 NULLIFY_INS (def);
1354                                 info->reg = -1;
1355                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1356                                 NULLIFY_INS (def);
1357                                 info->reg = -1;
1358                         } else if (MONO_IS_PHI (def)) {
1359                                 int j;
1360                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1361                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1362                                         add_to_dce_worklist (cfg, info, u, &work_list);
1363                                 }
1364                                 NULLIFY_INS (def);
1365                                 info->reg = -1;
1366                         }
1367                         else if (def->opcode == OP_NOP) {
1368                         }
1369                         //else
1370                         //mono_print_ins (def);
1371                 }
1372
1373         }
1374 }
1375
1376 #if 0
1377 void
1378 mono_ssa_strength_reduction (MonoCompile *cfg)
1379 {
1380         MonoBasicBlock *bb;
1381         int i;
1382
1383         g_assert (cfg->comp_done & MONO_COMP_SSA);
1384         g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1385         g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1386
1387         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1388                 GList *lp = bb->loop_blocks;
1389
1390                 if (lp) {
1391                         MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1392
1393                         /* we only consider loops with 2 in bblocks */
1394                         if (!h->in_count == 2)
1395                                 continue;
1396
1397                         for (i = 0; i < cfg->num_varinfo; i++) {
1398                                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1399
1400                                 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1401                                     info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1402                                         MonoInst *v = info->def->inst_i1;
1403
1404
1405                                         printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1406                                 }
1407                         }
1408                 }
1409         }
1410 }
1411 #endif
1412
1413 void
1414 mono_ssa_loop_invariant_code_motion (MonoCompile *cfg)
1415 {
1416         MonoBasicBlock *bb, *h, *idom;
1417         MonoInst *ins, *n, *tins;
1418         int i;
1419
1420         g_assert (cfg->comp_done & MONO_COMP_SSA);
1421         if (!(cfg->comp_done & MONO_COMP_LOOPS) || !(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1422                 return;
1423
1424         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1425                 GList *lp = bb->loop_blocks;
1426
1427                 if (!lp)
1428                         continue;
1429                 h = (MonoBasicBlock *)lp->data;
1430                 if (bb != h)
1431                         continue;
1432                 MONO_BB_FOR_EACH_INS_SAFE (bb, n, ins) {
1433                         /*
1434                          * Try to move instructions out of loop headers into the preceeding bblock.
1435                          */
1436                         if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS || ins->opcode == OP_AOTCONST || ins->opcode == OP_GENERIC_CLASS_INIT) {
1437                                 gboolean skip;
1438                                 int sreg;
1439
1440                                 idom = h->idom;
1441                                 /*
1442                                  * h->nesting is needed to work around:
1443                                  * http://llvm.org/bugs/show_bug.cgi?id=17868
1444                                  */
1445                                 if (!(idom && idom->last_ins && idom->last_ins->opcode == OP_BR && idom->last_ins->inst_target_bb == h && h->nesting == 1)) {
1446                                         continue;
1447                                 }
1448
1449                                 /*
1450                                  * Make sure there are no instructions with side effects before ins.
1451                                  */
1452                                 skip = FALSE;
1453                                 MONO_BB_FOR_EACH_INS (bb, tins) {
1454                                         if (tins == ins)
1455                                                 break;
1456                                         if (!MONO_INS_HAS_NO_SIDE_EFFECT (tins)) {
1457                                                 skip = TRUE;
1458                                                 break;
1459                                         }
1460                                 }
1461                                 if (skip) {
1462                                         /*
1463                                           printf ("%s\n", mono_method_full_name (cfg->method, TRUE));
1464                                           mono_print_ins (tins);
1465                                         */
1466                                         continue;
1467                                 }
1468
1469                                 /* Make sure we don't move the instruction before the def of its sreg */
1470                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS)
1471                                         sreg = ins->sreg1;
1472                                 else
1473                                         sreg = -1;
1474                                 if (sreg != -1) {
1475                                         MonoInst *tins, *var;
1476
1477                                         skip = FALSE;
1478                                         for (tins = ins->prev; tins; tins = tins->prev) {
1479                                                 const char *spec = INS_INFO (tins->opcode);
1480
1481                                                 if (tins->opcode == OP_MOVE && tins->dreg == sreg) {
1482                                                         sreg = tins->sreg1;
1483                                                 } if (spec [MONO_INST_DEST] != ' ' && tins->dreg == sreg) {
1484                                                         skip = TRUE;
1485                                                         break;
1486                                                 }
1487                                         }
1488                                         if (skip)
1489                                                 continue;
1490                                         var = get_vreg_to_inst (cfg, sreg);
1491                                         if (var && (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1492                                                 continue;
1493                                         ins->sreg1 = sreg;
1494                                 }
1495
1496                                 if (cfg->verbose_level > 1) {
1497                                         printf ("licm in BB%d on ", bb->block_num);
1498                                         mono_print_ins (ins);
1499                                 }
1500                                 //{ static int count = 0; count ++; printf ("%d\n", count); }
1501                                 MONO_REMOVE_INS (bb, ins);
1502                                 mono_bblock_insert_before_ins (idom, idom->last_ins, ins);
1503                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN)
1504                                         idom->has_array_access = TRUE;
1505                         }
1506                 }
1507         }
1508
1509         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1510         for (i = 0; i < cfg->num_varinfo; i++) {
1511                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1512                 info->def = NULL;
1513                 info->uses = NULL;
1514         }
1515 }
1516
1517 #endif /* DISABLE_JIT */