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  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  10  */
  11 #include <config.h>
  12 #include <string.h>
  13 #include <mono/metadata/debug-helpers.h>
  14 #include <mono/metadata/mempool.h>
  15 #include <mono/metadata/mempool-internals.h>
  16
  17 #ifndef DISABLE_JIT
  18
  19 #include "mini.h"
  20 #ifdef HAVE_ALLOCA_H
  21 #include <alloca.h>
  22 #endif
  23
  24 #define CREATE_PRUNED_SSA
  25
  26 //#define DEBUG_SSA 1
  27
  28 #define NEW_PHI(cfg,dest,val) do {      \
  29         MONO_INST_NEW ((cfg), (dest), OP_PHI); \
  30         (dest)->inst_c0 = (val);                                                           \
  31         } while (0)
  32
  33 typedef struct {
  34         MonoBasicBlock *bb;
  35         MonoInst *inst;
  36 } MonoVarUsageInfo;
  37
  38 static void
  39 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
  40 {
  41         int i;
  42
  43         for (i = 0; i < bb->out_count; i++) {
  44                 if (bb->out_bb [i] == target) {
  45                         bb->out_bb [i] = bb->out_bb [--bb->out_count];
  46                         break;
  47                 }
  48         }
  49         for (i = 0; i < target->in_count; i++) {
  50                 if (target->in_bb [i] == bb) {
  51                         target->in_bb [i] = target->in_bb [--target->in_count];
  52                         break;
  53
  54                 }
  55         }
  56 }
  57
  58 static void
  59 unlink_unused_bblocks (MonoCompile *cfg)
  60 {
  61         int i, j;
  62         MonoBasicBlock *bb;
  63
  64         g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
  65
  66         if (G_UNLIKELY (cfg->verbose_level > 1))
  67                 printf ("\nUNLINK UNUSED BBLOCKS:\n");
  68
  69         for (bb = cfg->bb_entry; bb && bb->next_bb;) {
  70                 if (!(bb->next_bb->flags & BB_REACHABLE)) {
  71                         bb->next_bb = bb->next_bb->next_bb;
  72                 } else
  73                         bb = bb->next_bb;
  74         }
  75
  76         for (i = 1; i < cfg->num_bblocks; i++) {
  77                 bb = cfg->bblocks [i];
  78
  79                 if (!(bb->flags & BB_REACHABLE)) {
  80                         for (j = 0; j < bb->in_count; j++) {
  81                                 unlink_target (bb->in_bb [j], bb);
  82                         }
  83                         for (j = 0; j < bb->out_count; j++) {
  84                                 unlink_target (bb, bb->out_bb [j]);
  85                         }
  86                         if (G_UNLIKELY (cfg->verbose_level > 1))
  87                                 printf ("\tUnlinked BB%d\n", bb->block_num);
  88                 }
  89
  90         }
  91 }
  92
  93 /**
  94  * remove_bb_from_phis:
  95  *
  96  *   Remove BB from the PHI statements in TARGET.
  97  */
  98 static void
  99 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
 100 {
 101         MonoInst *ins;
 102         int i, j;
 103
 104         for (i = 0; i < target->in_count; i++) {
 105                 if (target->in_bb [i] == bb) {
 106                         break;
 107                 }
 108         }
 109         g_assert (i < target->in_count);
 110
 111         for (ins = target->code; ins; ins = ins->next) {
 112                 if (MONO_IS_PHI (ins)) {
 113                         for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
 114                                 ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
 115                         ins->inst_phi_args [0] --;
 116                 }
 117                 else
 118                         break;
 119         }
 120 }
 121
 122 static inline int
 123 op_phi_to_move (int opcode)
 124 {
 125         switch (opcode) {
 126         case OP_PHI:
 127                 return OP_MOVE;
 128         case OP_FPHI:
 129                 return OP_FMOVE;
 130         case OP_VPHI:
 131                 return OP_VMOVE;
 132         case OP_XPHI:
 133                 return OP_XMOVE;
 134         default:
 135                 g_assert_not_reached ();
 136         }
 137
 138         return -1;
 139 }
 140
 141 static inline void
 142 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
 143 {
 144         MonoMethodVar *info;
 145         MonoVarUsageInfo *ui = (MonoVarUsageInfo *)mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
 146
 147         info = MONO_VARINFO (cfg, var->inst_c0);
 148
 149         ui->bb = bb;
 150         ui->inst = ins;
 151         info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
 152 }
 153
 154 typedef struct {
 155         MonoInst *var;
 156         int idx;
 157 } RenameInfo;
 158
 159 /**
 160  * mono_ssa_rename_vars:
 161  *
 162  *  Implement renaming of SSA variables. Also compute def-use information in parallel.
 163  * @stack_history points to an area of memory which can be used for storing changes
 164  * made to the stack, so they can be reverted later.
 165  */
 166 static void
 167 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)
 168 {
 169         MonoInst *ins, *new_var;
 170         int i, j, idx;
 171         GSList *tmp;
 172         int stack_history_len = 0;
 173
 174         if (cfg->verbose_level >= 4)
 175                 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
 176
 177         /* First pass: Create new vars */
 178         for (ins = bb->code; ins; ins = ins->next) {
 179                 const char *spec = INS_INFO (ins->opcode);
 180                 int num_sregs;
 181                 int sregs [MONO_MAX_SRC_REGS];
 182
 183 #ifdef DEBUG_SSA
 184                 printf ("\tProcessing "); mono_print_ins (ins);
 185 #endif
 186                 if (ins->opcode == OP_NOP)
 187                         continue;
 188
 189                 /* SREGs */
 190                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 191                 for (i = 0; i < num_sregs; ++i) {
 192                         if (spec [MONO_INST_SRC1 + i] != ' ') {
 193                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 194                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 195                                         int idx = var->inst_c0;
 196                                         if (stack [idx]) {
 197                                                 if (var->opcode != OP_ARG)
 198                                                         g_assert (stack [idx]);
 199                                                 sregs [i] = stack [idx]->dreg;
 200                                                 record_use (cfg, stack [idx], bb, ins);
 201                                         }
 202                                         else
 203                                                 record_use (cfg, var, bb, ins);
 204                                 }
 205                                 else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
 206                                         sregs [i] = lvreg_stack [sregs [i]];
 207                         }
 208                 }
 209                 mono_inst_set_src_registers (ins, sregs);
 210
 211                 if (MONO_IS_STORE_MEMBASE (ins)) {
 212                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 213                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 214                                 int idx = var->inst_c0;
 215                                 if (stack [idx]) {
 216                                         if (var->opcode != OP_ARG)
 217                                                 g_assert (stack [idx]);
 218                                         ins->dreg = stack [idx]->dreg;
 219                                         record_use (cfg, stack [idx], bb, ins);
 220                                 }
 221                                 else
 222                                         record_use (cfg, var, bb, ins);
 223                         }
 224                         else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
 225                                 ins->dreg = lvreg_stack [ins->dreg];
 226                 }
 227
 228                 /* DREG */
 229                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 230                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 231                         MonoMethodVar *info;
 232
 233                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 234                                 idx = var->inst_c0;
 235                                 g_assert (idx < max_vars);
 236
 237                                 if (var->opcode == OP_ARG)
 238                                         originals_used [idx] = TRUE;
 239
 240                                 /* FIXME: */
 241                                 g_assert (stack_history_len < stack_history_size);
 242                                 stack_history [stack_history_len].var = stack [idx];
 243                                 stack_history [stack_history_len].idx = idx;
 244                                 stack_history_len ++;
 245
 246                                 if (originals_used [idx]) {
 247                                         new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
 248                                         new_var->flags = var->flags;
 249                                         MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
 250
 251                                         if (cfg->verbose_level >= 4)
 252                                                 printf ("  R%d -> R%d\n", var->dreg, new_var->dreg);
 253
 254                                         stack [idx] = new_var;
 255
 256                                         ins->dreg = new_var->dreg;
 257                                         var = new_var;
 258                                 }
 259                                 else {
 260                                         stack [idx] = var;
 261                                         originals_used [idx] = TRUE;
 262                                 }
 263
 264                                 info = MONO_VARINFO (cfg, var->inst_c0);
 265                                 info->def = ins;
 266                                 info->def_bb = bb;
 267                         }
 268                         else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
 269                                 /* Perform renaming for local vregs */
 270                                 lvreg_stack [ins->dreg] = vreg_is_ref (cfg, ins->dreg) ? mono_alloc_ireg_ref (cfg) : mono_alloc_preg (cfg);
 271                                 ins->dreg = lvreg_stack [ins->dreg];
 272                         }
 273                         else
 274                                 lvreg_defined [ins->dreg] = TRUE;
 275                 }
 276
 277 #ifdef DEBUG_SSA
 278                 printf ("\tAfter processing "); mono_print_ins (ins);
 279 #endif
 280
 281         }
 282
 283         /* Rename PHI arguments in succeeding bblocks */
 284         for (i = 0; i < bb->out_count; i++) {
 285                 MonoBasicBlock *n = bb->out_bb [i];
 286
 287                 for (j = 0; j < n->in_count; j++)
 288                         if (n->in_bb [j] == bb)
 289                                 break;
 290
 291                 for (ins = n->code; ins; ins = ins->next) {
 292                         if (MONO_IS_PHI (ins)) {
 293                                 idx = ins->inst_c0;
 294                                 if (stack [idx])
 295                                         new_var = stack [idx];
 296                                 else
 297                                         new_var = cfg->varinfo [idx];
 298 #ifdef DEBUG_SSA
 299                                 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
 300 #endif
 301                                 ins->inst_phi_args [j + 1] = new_var->dreg;
 302                                 record_use (cfg,  new_var, n, ins);
 303                                 if (G_UNLIKELY (cfg->verbose_level >= 4))
 304                                         printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
 305                         }
 306                         else
 307                                 /* The phi nodes are at the beginning of the bblock */
 308                                 break;
 309                 }
 310         }
 311
 312         if (bb->dominated) {
 313                 for (tmp = bb->dominated; tmp; tmp = tmp->next) {
 314                         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);
 315                 }
 316         }
 317
 318         /* Restore stack */
 319         for (i = stack_history_len - 1; i >= 0; i--) {
 320                 stack [stack_history [i].idx] = stack_history [i].var;
 321         }
 322
 323         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 324 }
 325
 326 void
 327 mono_ssa_compute (MonoCompile *cfg)
 328 {
 329         int i, j, idx, bitsize;
 330         MonoBitSet *set;
 331         MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
 332         MonoInst *ins, **stack;
 333         guint8 *buf, *buf_start;
 334         RenameInfo *stack_history;
 335         int stack_history_size;
 336         gboolean *originals;
 337         guint32 *lvreg_stack;
 338         gboolean *lvreg_defined;
 339
 340         g_assert (!(cfg->comp_done & MONO_COMP_SSA));
 341
 342         g_assert (!cfg->disable_ssa);
 343
 344         if (cfg->verbose_level >= 4)
 345                 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
 346
 347 #ifdef CREATE_PRUNED_SSA
 348         /* we need liveness for pruned SSA */
 349         if (!(cfg->comp_done & MONO_COMP_LIVENESS))
 350                 mono_analyze_liveness (cfg);
 351 #endif
 352
 353         mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
 354
 355         bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
 356         buf = buf_start = (guint8 *)g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
 357
 358         for (i = 0; i < cfg->num_varinfo; ++i) {
 359                 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
 360                 buf += bitsize;
 361                 vinfo [i].idx = i;
 362                 /* implicit reference at start */
 363                 if (cfg->varinfo [i]->opcode == OP_ARG)
 364                         mono_bitset_set_fast (vinfo [i].def_in, 0);
 365         }
 366
 367         for (i = 0; i < cfg->num_bblocks; ++i) {
 368                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 369                         if (ins->opcode == OP_NOP)
 370                                 continue;
 371
 372                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 373                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 374                         }
 375                 }
 376         }
 377
 378         /* insert phi functions */
 379         for (i = 0; i < cfg->num_varinfo; ++i) {
 380                 MonoInst *var = cfg->varinfo [i];
 381
 382 #if SIZEOF_REGISTER == 4
 383                 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
 384                         continue;
 385 #endif
 386                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 387                         continue;
 388
 389                 /* Most variables have only one definition */
 390                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 391                         continue;
 392
 393                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 394
 395                 if (cfg->verbose_level >= 4) {
 396                         if (mono_bitset_count (set) > 0) {
 397                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 398                                 mono_blockset_print (cfg, set, "", -1);
 399                         }
 400                 }
 401
 402                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 403                         MonoBasicBlock *bb = cfg->bblocks [idx];
 404
 405                         /* fixme: create pruned SSA? we would need liveness information for that */
 406
 407                         if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
 408                                 continue;
 409
 410                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 411                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 412                                 continue;
 413                         }
 414
 415                         NEW_PHI (cfg, ins, i);
 416
 417                         switch (var->type) {
 418                         case STACK_I4:
 419                         case STACK_I8:
 420                         case STACK_PTR:
 421                         case STACK_MP:
 422                         case STACK_OBJ:
 423                                 ins->opcode = OP_PHI;
 424                                 break;
 425                         case STACK_R8:
 426                                 ins->opcode = OP_FPHI;
 427                                 break;
 428                         case STACK_VTYPE:
 429                                 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
 430                                 break;
 431                         }
 432
 433                         if (var->inst_vtype->byref)
 434                                 ins->klass = mono_defaults.int_class;
 435                         else
 436                                 ins->klass = var->klass;
 437
 438                         ins->inst_phi_args = (int *)mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 439                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 440
 441                         /* For debugging */
 442                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 443                                 ins->inst_phi_args [j + 1] = -1;
 444
 445                         ins->dreg = cfg->varinfo [i]->dreg;
 446
 447                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 448
 449 #ifdef DEBUG_SSA
 450                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 451 #endif
 452                 }
 453         }
 454
 455         /* free the stuff */
 456         g_free (vinfo);
 457         g_free (buf_start);
 458
 459         /* Renaming phase */
 460
 461         stack = (MonoInst **)alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 462         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 463
 464         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 465         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 466         stack_history_size = 10240;
 467         stack_history = g_new (RenameInfo, stack_history_size);
 468         originals = g_new0 (gboolean, cfg->num_varinfo);
 469         mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 470         g_free (stack_history);
 471         g_free (originals);
 472         g_free (lvreg_stack);
 473         g_free (lvreg_defined);
 474
 475         if (cfg->verbose_level >= 4)
 476                 printf ("\nEND COMPUTE SSA.\n\n");
 477
 478         cfg->comp_done |= MONO_COMP_SSA;
 479 }
 480
 481 /*
 482  * mono_ssa_remove_gsharedvt:
 483  *
 484  *   Same as mono_ssa_remove, but only remove phi nodes for gsharedvt variables.
 485  */
 486 void
 487 mono_ssa_remove_gsharedvt (MonoCompile *cfg)
 488 {
 489         MonoInst *ins, *var, *move;
 490         int i, j, first;
 491
 492         /*
 493          * When compiling gsharedvt code, we need to get rid of the VPHI instructions,
 494          * since they cannot be handled later in the llvm backend.
 495          */
 496         g_assert (cfg->comp_done & MONO_COMP_SSA);
 497
 498         for (i = 0; i < cfg->num_bblocks; ++i) {
 499                 MonoBasicBlock *bb = cfg->bblocks [i];
 500
 501                 if (cfg->verbose_level >= 4)
 502                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 503
 504                 for (ins = bb->code; ins; ins = ins->next) {
 505                         if (!(MONO_IS_PHI (ins) && ins->opcode == OP_VPHI && mini_is_gsharedvt_variable_type (&ins->klass->byval_arg)))
 506                                 continue;
 507
 508                         g_assert (ins->inst_phi_args [0] == bb->in_count);
 509                         var = get_vreg_to_inst (cfg, ins->dreg);
 510
 511                         /* Check for PHI nodes where all the inputs are the same */
 512                         first = ins->inst_phi_args [1];
 513
 514                         for (j = 1; j < bb->in_count; ++j)
 515                                 if (first != ins->inst_phi_args [j + 1])
 516                                         break;
 517
 518                         if ((bb->in_count > 1) && (j == bb->in_count)) {
 519                                 ins->opcode = op_phi_to_move (ins->opcode);
 520                                 if (ins->opcode == OP_VMOVE)
 521                                         g_assert (ins->klass);
 522                                 ins->sreg1 = first;
 523                         } else {
 524                                 for (j = 0; j < bb->in_count; j++) {
 525                                         MonoBasicBlock *pred = bb->in_bb [j];
 526                                         int sreg = ins->inst_phi_args [j + 1];
 527
 528                                         if (cfg->verbose_level >= 4)
 529                                                 printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 530                                         if (var->dreg != sreg) {
 531                                                 MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 532                                                 if (move->opcode == OP_VMOVE) {
 533                                                         g_assert (ins->klass);
 534                                                         move->klass = ins->klass;
 535                                                 }
 536                                                 move->dreg = var->dreg;
 537                                                 move->sreg1 = sreg;
 538                                                 mono_add_ins_to_end (pred, move);
 539                                         }
 540                                 }
 541
 542                                 NULLIFY_INS (ins);
 543                         }
 544                 }
 545         }
 546 }
 547
 548 void
 549 mono_ssa_remove (MonoCompile *cfg)
 550 {
 551         MonoInst *ins, *var, *move;
 552         int bbindex, i, j, first;
 553
 554         g_assert (cfg->comp_done & MONO_COMP_SSA);
 555
 556         for (i = 0; i < cfg->num_bblocks; ++i) {
 557                 MonoBasicBlock *bb = cfg->bblocks [i];
 558
 559                 if (cfg->verbose_level >= 4)
 560                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 561
 562                 for (ins = bb->code; ins; ins = ins->next) {
 563                         if (MONO_IS_PHI (ins)) {
 564                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 565                                 var = get_vreg_to_inst (cfg, ins->dreg);
 566
 567                                 /* Check for PHI nodes where all the inputs are the same */
 568                                 first = ins->inst_phi_args [1];
 569
 570                                 for (j = 1; j < bb->in_count; ++j)
 571                                         if (first != ins->inst_phi_args [j + 1])
 572                                                 break;
 573
 574                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 575                                         ins->opcode = op_phi_to_move (ins->opcode);
 576                                         if (ins->opcode == OP_VMOVE)
 577                                                 g_assert (ins->klass);
 578                                         ins->sreg1 = first;
 579                                 } else {
 580                                         for (j = 0; j < bb->in_count; j++) {
 581                                                 MonoBasicBlock *pred = bb->in_bb [j];
 582                                                 int sreg = ins->inst_phi_args [j + 1];
 583
 584                                                 if (cfg->verbose_level >= 4)
 585                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 586                                                 if (var->dreg != sreg) {
 587                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 588                                                         if (move->opcode == OP_VMOVE) {
 589                                                                 g_assert (ins->klass);
 590                                                                 move->klass = ins->klass;
 591                                                         }
 592                                                         move->dreg = var->dreg;
 593                                                         move->sreg1 = sreg;
 594                                                         mono_add_ins_to_end (pred, move);
 595                                                 }
 596                                         }
 597
 598                                         NULLIFY_INS (ins);
 599                                 }
 600                         }
 601                 }
 602         }
 603
 604         if (cfg->verbose_level >= 4) {
 605                 for (i = 0; i < cfg->num_bblocks; ++i) {
 606                         MonoBasicBlock *bb = cfg->bblocks [i];
 607
 608                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 609                 }
 610         }
 611
 612         /*
 613          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 614          * the variables if possible. Since the newly introduced SSA variables don't
 615          * have overlapping live ranges (because we don't do agressive optimization), we
 616          * can coalesce them into the original variable.
 617          */
 618
 619         for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
 620                 MonoBasicBlock *bb = cfg->bblocks [bbindex];
 621
 622                 for (ins = bb->code; ins; ins = ins->next) {
 623                         const char *spec = INS_INFO (ins->opcode);
 624                         int num_sregs;
 625                         int sregs [MONO_MAX_SRC_REGS];
 626
 627                         if (ins->opcode == OP_NOP)
 628                                 continue;
 629
 630                         if (spec [MONO_INST_DEST] != ' ') {
 631                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 632
 633                                 if (var) {
 634                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 635
 636                                         /*
 637                                          * The third condition avoids coalescing with variables eliminated
 638                                          * during deadce.
 639                                          */
 640                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 641                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 642                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 643                                         }
 644                                 }
 645                         }
 646
 647                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 648                         for (i = 0; i < num_sregs; ++i) {
 649                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 650
 651                                 if (var) {
 652                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 653
 654                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 655                                                 printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
 656                                                 sregs [i] = cfg->varinfo [vmv->reg]->dreg;
 657                                         }
 658                                 }
 659                         }
 660                         mono_inst_set_src_registers (ins, sregs);
 661                 }
 662         }
 663
 664         for (i = 0; i < cfg->num_varinfo; ++i) {
 665                 MONO_VARINFO (cfg, i)->reg = -1;
 666         }
 667
 668         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 669                 unlink_unused_bblocks (cfg);
 670
 671         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 672
 673         cfg->comp_done &= ~MONO_COMP_SSA;
 674 }
 675
 676 static void
 677 mono_ssa_create_def_use (MonoCompile *cfg)
 678 {
 679         MonoBasicBlock *bb;
 680         MonoInst *ins;
 681         int i;
 682
 683         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 684
 685         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 686                 for (ins = bb->code; ins; ins = ins->next) {
 687                         const char *spec = INS_INFO (ins->opcode);
 688                         MonoMethodVar *info;
 689                         int num_sregs;
 690                         int sregs [MONO_MAX_SRC_REGS];
 691
 692                         if (ins->opcode == OP_NOP)
 693                                 continue;
 694
 695                         /* SREGs */
 696                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 697                         for (i = 0; i < num_sregs; ++i) {
 698                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 699                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 700                                         record_use (cfg, var, bb, ins);
 701                         }
 702
 703                         if (MONO_IS_STORE_MEMBASE (ins)) {
 704                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 705                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 706                                         record_use (cfg, var, bb, ins);
 707                         }
 708
 709                         if (MONO_IS_PHI (ins)) {
 710                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 711                                         g_assert (ins->inst_phi_args [i] != -1);
 712                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 713                                 }
 714                         }
 715
 716                         /* DREG */
 717                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 718                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 719
 720                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 721                                         info = MONO_VARINFO (cfg, var->inst_c0);
 722                                         info->def = ins;
 723                                         info->def_bb = bb;
 724                                 }
 725                         }
 726                 }
 727         }
 728
 729         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 730 }
 731
 732 static void
 733 mono_ssa_copyprop (MonoCompile *cfg)
 734 {
 735         int i, index;
 736         GList *l;
 737
 738         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 739
 740         for (index = 0; index < cfg->num_varinfo; ++index) {
 741                 MonoInst *var = cfg->varinfo [index];
 742                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 743
 744                 if (info->def && (MONO_IS_MOVE (info->def))) {
 745                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 746
 747                         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))) {
 748                                 /* Rewrite all uses of var to be uses of var2 */
 749                                 int dreg = var->dreg;
 750                                 int sreg1 = var2->dreg;
 751
 752                                 l = info->uses;
 753                                 while (l) {
 754                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 755                                         MonoInst *ins = u->inst;
 756                                         GList *next = l->next;
 757                                         int num_sregs;
 758                                         int sregs [MONO_MAX_SRC_REGS];
 759
 760                                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 761                                         for (i = 0; i < num_sregs; ++i) {
 762                                                 if (sregs [i] == dreg)
 763                                                         break;
 764                                         }
 765                                         if (i < num_sregs) {
 766                                                 g_assert (sregs [i] == dreg);
 767                                                 sregs [i] = sreg1;
 768                                                 mono_inst_set_src_registers (ins, sregs);
 769                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 770                                                 ins->dreg = sreg1;
 771                                         } else if (MONO_IS_PHI (ins)) {
 772                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 773                                                         int sreg = ins->inst_phi_args [i];
 774                                                         if (sreg == var->dreg)
 775                                                                 break;
 776                                                 }
 777                                                 g_assert (i > 0);
 778                                                 ins->inst_phi_args [i] = sreg1;
 779                                         }
 780                                         else
 781                                                 g_assert_not_reached ();
 782
 783                                         record_use (cfg, var2, u->bb, ins);
 784
 785                                         l = next;
 786                                 }
 787
 788                                 info->uses = NULL;
 789                         }
 790                 }
 791         }
 792
 793         if (cfg->verbose_level >= 4) {
 794                 MonoBasicBlock *bb;
 795
 796                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 797                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 798         }
 799 }
 800
 801 static int
 802 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 803 {
 804         MonoInst *args [MONO_MAX_SRC_REGS];
 805         int rs [MONO_MAX_SRC_REGS];
 806         MonoInst *c0;
 807         gboolean const_args = TRUE;
 808         const char *spec = INS_INFO (ins->opcode);
 809         int num_sregs, i;
 810         int sregs [MONO_MAX_SRC_REGS];
 811
 812         /* Short-circuit this */
 813         if (ins->opcode == OP_ICONST) {
 814                 *res = ins;
 815                 return 1;
 816         }
 817
 818         if (ins->opcode == OP_NOP)
 819                 return 2;
 820
 821         num_sregs = mono_inst_get_src_registers (ins, sregs);
 822         for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
 823                 args [i] = NULL;
 824         for (i = 0; i < num_sregs; ++i) {
 825                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 826
 827                 rs [i] = 2;
 828                 args [i] = carray [sregs [i]];
 829                 if (args [i])
 830                         rs [i] = 1;
 831                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 832                         rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 833                 if (rs [i] != 1)
 834                         const_args = FALSE;
 835         }
 836
 837         c0 = NULL;
 838
 839         if (num_sregs > 0 && const_args) {
 840                 g_assert (num_sregs <= 2);
 841                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 842                         // Cached value
 843                         *res = carray [ins->dreg];
 844                         return 1;
 845                 }
 846                 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
 847                 if (c0) {
 848                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 849                                 printf ("\t cfold -> ");
 850                                 mono_print_ins (c0);
 851                         }
 852                         *res = c0;
 853                         return 1;
 854                 }
 855                 else
 856                         /* Can't cfold this ins */
 857                         return 2;
 858         }
 859
 860         if (num_sregs == 0)
 861                 return 2;
 862         for (i = 0; i < num_sregs; ++i) {
 863                 if (rs [i] == 2)
 864                         return 2;
 865         }
 866         return 0;
 867 }
 868
 869 static inline void
 870 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 871 {
 872         if (info->cpstate >= state)
 873                 return;
 874
 875         info->cpstate = state;
 876
 877         if (G_UNLIKELY (cfg->verbose_level > 1))
 878                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 879
 880         if (state == 1)
 881                 g_assert (c0);
 882
 883         carray [cfg->varinfo [info->idx]->dreg] = c0;
 884
 885         if (!g_list_find (*cvars, info)) {
 886                 *cvars = g_list_prepend (*cvars, info);
 887         }
 888 }
 889
 890 static inline void
 891 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 892 {
 893         if (G_UNLIKELY (cfg->verbose_level > 1))
 894                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 895
 896     if (!(bb->flags &  BB_REACHABLE)) {
 897             bb->flags |= BB_REACHABLE;
 898                 *bblist = g_list_prepend (*bblist, bb);
 899         }
 900 }
 901
 902 static void
 903 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 904 {
 905         const char *spec = INS_INFO (ins->opcode);
 906
 907         if (ins->opcode == OP_NOP)
 908                 return;
 909
 910         if (cfg->verbose_level > 1)
 911                 mono_print_ins (ins);
 912
 913         /* FIXME: Support longs/floats */
 914         /* FIXME: Work on vregs as well */
 915
 916         if (MONO_IS_PHI (ins)) {
 917                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 918                 MonoInst *c0 = NULL;
 919                 int j;
 920
 921                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 922                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 923                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 924                         MonoInst *src = mv->def;
 925
 926                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 927                                 continue;
 928
 929                         if (!mv->def || !src || mv->cpstate == 2) {
 930                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 931                                 break;
 932                         }
 933
 934                         if (mv->cpstate == 0)
 935                                 continue;
 936
 937                         g_assert (carray [var->dreg]);
 938
 939                         if (!c0)
 940                                 c0 = carray [var->dreg];
 941
 942                         /* FIXME: */
 943                         if (c0->opcode != OP_ICONST) {
 944                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 945                                 break;
 946                         }
 947
 948                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 949                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 950                                 break;
 951                         }
 952                 }
 953
 954                 if (c0 && info->cpstate < 1) {
 955                         change_varstate (cfg, cvars, info, 1, c0, carray);
 956
 957                         g_assert (c0->opcode == OP_ICONST);
 958                 }
 959         }
 960         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 961                 MonoInst *var, *c0;
 962                 int state;
 963
 964                 if (spec [MONO_INST_DEST] !=  ' ')
 965                         var = get_vreg_to_inst (cfg, ins->dreg);
 966                 else
 967                         var = NULL;
 968
 969                 c0 = NULL;
 970                 state = evaluate_ins (cfg, ins, &c0, carray);
 971
 972                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 973                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 974
 975                         if (info->cpstate < 2) {
 976                                 if (state == 1)
 977                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 978                                 else if (state == 2)
 979                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 980                         }
 981                 }
 982                 else if (!var && (ins->dreg != -1)) {
 983                         /*
 984                          * We don't record def-use information for local vregs since it would be
 985                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 986                          * the same bblock, so they will be examined after the definition.
 987                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 988                          */
 989                         if (c0) {
 990                                 carray [ins->dreg] = c0;
 991                         } else {
 992                                 if (carray [ins->dreg]) {
 993                                         /*
 994                                          * The state of the vreg changed from constant to non-constant
 995                                          * -> need to rescan the whole bblock.
 996                                          */
 997                                         carray [ins->dreg] = NULL;
 998                                         /* FIXME: Speed this up */
 999
1000                                         if (!g_list_find (*bblist, bb))
1001                                                 *bblist = g_list_prepend (*bblist, bb);
1002                                 }
1003                         }
1004                 }
1005
1006                 if (MONO_IS_JUMP_TABLE (ins)) {
1007                         int i;
1008                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1009
1010                         if (!ins->next || ins->next->opcode != OP_PADD) {
1011                                 /* The PADD was optimized away */
1012                                 /* FIXME: handle this as well */
1013                                 for (i = 0; i < table->table_size; i++)
1014                                         if (table->table [i])
1015                                                 add_cprop_bb (cfg, table->table [i], bblist);
1016                                 return;
1017                         }
1018
1019                         g_assert (ins->next->opcode == OP_PADD);
1020                         g_assert (ins->next->sreg1 == ins->dreg);
1021
1022                         if (carray [ins->next->sreg2]) {
1023 #if SIZEOF_REGISTER == 8
1024                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1025 #else
1026                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1027 #endif
1028                                 if ((idx < 0) || (idx >= table->table_size))
1029                                         /* Out-of-range, no branch is executed */
1030                                         return;
1031                                 else
1032                                         if (table->table [idx])
1033                                                 add_cprop_bb (cfg, table->table [idx], bblist);
1034                         }
1035                         else {
1036                                 for (i = 0; i < table->table_size; i++)
1037                                         if (table->table [i])
1038                                                 add_cprop_bb (cfg, table->table [i], bblist);
1039                         }
1040                 }
1041
1042                 if (ins->opcode == OP_SWITCH) {
1043                         int i;
1044                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)ins->inst_p0;
1045
1046                         for (i = 0; i < table->table_size; i++)
1047                                 if (table->table [i])
1048                                         add_cprop_bb (cfg, table->table [i], bblist);
1049                 }
1050
1051                 /* Handle COMPARE+BRCOND pairs */
1052                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
1053                         if (c0) {
1054                                 g_assert (c0->opcode == OP_ICONST);
1055
1056                                 if (c0->inst_c0)
1057                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
1058                                 else
1059                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
1060                         }
1061                         else {
1062                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1063                         }
1064
1065                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1066                 }
1067         } else if (ins->opcode == OP_BR) {
1068                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1069         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1070                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1071                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1072                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1073                         if (ins->inst_false_bb)
1074                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1075         } else {
1076                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1077                         if (ins->inst_false_bb)
1078                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1079                 }
1080         }
1081 }
1082
1083 /**
1084  * fold_ins:
1085  *
1086  *   Replace INS with its constant value, if it exists
1087  */
1088 static void
1089 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1090 {
1091         const char *spec = INS_INFO (ins->opcode);
1092         int opcode2;
1093         int num_sregs = mono_inst_get_num_src_registers (ins);
1094
1095         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1096                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1097                         /* Perform constant folding */
1098                         /* FIXME: */
1099                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1100                         ins->opcode = OP_ICONST;
1101                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1102                         MONO_INST_NULLIFY_SREGS (ins);
1103                 } else if (num_sregs == 2 && carray [ins->sreg2]) {
1104                         /* Perform op->op_imm conversion */
1105                         opcode2 = mono_op_to_op_imm (ins->opcode);
1106                         if (opcode2 != -1) {
1107                                 ins->opcode = opcode2;
1108                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1109                                 ins->sreg2 = -1;
1110
1111                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1112                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1113                         }
1114                 } else {
1115                         /* FIXME: Handle 3 op insns */
1116                 }
1117
1118                 if (MONO_IS_JUMP_TABLE (ins)) {
1119                         int i;
1120                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1121
1122                         if (!ins->next || ins->next->opcode != OP_PADD) {
1123                                 /* The PADD was optimized away */
1124                                 /* FIXME: handle this as well */
1125                                 return;
1126                         }
1127
1128                         g_assert (ins->next->opcode == OP_PADD);
1129                         g_assert (ins->next->sreg1 == ins->dreg);
1130                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1131
1132                         if (carray [ins->next->sreg2]) {
1133                                 /* Convert to a simple branch */
1134 #if SIZEOF_REGISTER == 8
1135                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1136 #else
1137                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1138 #endif
1139
1140                                 if (!((idx >= 0) && (idx < table->table_size))) {
1141                                         /* Out of range, eliminate the whole switch */
1142                                         for (i = 0; i < table->table_size; ++i) {
1143                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1144                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1145                                         }
1146
1147                                         NULLIFY_INS (ins);
1148                                         NULLIFY_INS (ins->next);
1149                                         NULLIFY_INS (ins->next->next);
1150                                         if (ins->next->next->next)
1151                                                 NULLIFY_INS (ins->next->next->next);
1152
1153                                         return;
1154                                 }
1155
1156                                 if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
1157                                         /* A one-way switch which got optimized away */
1158                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1159                                                 printf ("\tNo cfold on ");
1160                                                 mono_print_ins (ins);
1161                                         }
1162                                         return;
1163                                 }
1164
1165                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1166                                         printf ("\tcfold on ");
1167                                         mono_print_ins (ins);
1168                                 }
1169
1170                                 /* Unlink target bblocks */
1171                                 for (i = 0; i < table->table_size; ++i) {
1172                                         if (table->table [i] != table->table [idx]) {
1173                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1174                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1175                                         }
1176                                 }
1177
1178                                 /* Change the OP_BR_REG to a simple branch */
1179                                 ins->next->next->next->opcode = OP_BR;
1180                                 ins->next->next->next->inst_target_bb = table->table [idx];
1181                                 ins->next->next->next->sreg1 = -1;
1182
1183                                 /* Nullify the other instructions */
1184                                 NULLIFY_INS (ins);
1185                                 NULLIFY_INS (ins->next);
1186                                 NULLIFY_INS (ins->next->next);
1187                         }
1188                 }
1189         }
1190         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1191                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1192                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1193                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1194                         ins->opcode = OP_BR;
1195                         ins->inst_target_bb = ins->inst_true_bb;
1196                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1197                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1198                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1199                         ins->opcode = OP_BR;
1200                         ins->inst_target_bb = ins->inst_false_bb;
1201                 }
1202         }
1203 }
1204
1205 void
1206 mono_ssa_cprop (MonoCompile *cfg)
1207 {
1208         MonoInst **carray;
1209         MonoBasicBlock *bb;
1210         GList *bblock_list, *cvars;
1211         GList *tmp;
1212         int i;
1213         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1214
1215         carray = g_new0 (MonoInst*, cfg->next_vreg);
1216
1217         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1218                 mono_ssa_create_def_use (cfg);
1219
1220         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1221         cfg->bb_entry->flags |= BB_REACHABLE;
1222
1223         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1224
1225         for (i = 0; i < cfg->num_varinfo; i++) {
1226                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1227                 if (!info->def)
1228                         info->cpstate = 2;
1229         }
1230
1231         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1232                 /*
1233                  * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1234                  * that would still allow unreachable try's to be removed.
1235                  */
1236                 if (bb->region)
1237                         add_cprop_bb (cfg, bb, &bblock_list);
1238         }
1239
1240         cvars = NULL;
1241
1242         while (bblock_list) {
1243                 MonoInst *inst;
1244
1245                 bb = (MonoBasicBlock *)bblock_list->data;
1246
1247                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1248
1249                 g_assert (bb->flags &  BB_REACHABLE);
1250
1251                 /*
1252                  * Some bblocks are linked to 2 others even through they fall through to the
1253                  * next bblock.
1254                  */
1255                 if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
1256                         for (i = 0; i < bb->out_count; ++i)
1257                                 add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
1258                 }
1259
1260                 if (cfg->verbose_level > 1)
1261                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1262
1263                 for (inst = bb->code; inst; inst = inst->next) {
1264                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1265                 }
1266
1267                 while (cvars) {
1268                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1269                         cvars = g_list_delete_link (cvars, cvars);
1270
1271                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1272                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1273                                 if (!(ui->bb->flags & BB_REACHABLE))
1274                                         continue;
1275                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1276                         }
1277                 }
1278         }
1279
1280         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1281                 MonoInst *inst;
1282                 for (inst = bb->code; inst; inst = inst->next) {
1283                         fold_ins (cfg, bb, inst, carray);
1284                 }
1285         }
1286
1287         g_free (carray);
1288
1289         cfg->comp_done |= MONO_COMP_REACHABILITY;
1290
1291         /* fixme: we should update usage infos during cprop, instead of computing it again */
1292         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1293         for (i = 0; i < cfg->num_varinfo; i++) {
1294                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1295                 info->def = NULL;
1296                 info->uses = NULL;
1297         }
1298 }
1299
1300 static inline void
1301 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1302 {
1303         GList *tmp;
1304
1305         *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1306
1307         for (tmp = use->uses; tmp; tmp = tmp->next) {
1308                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1309                 if (ui->inst == var->def) {
1310                         /* from the mempool */
1311                         use->uses = g_list_remove_link (use->uses, tmp);
1312                         break;
1313                 }
1314         }
1315 }
1316
1317 void
1318 mono_ssa_deadce (MonoCompile *cfg)
1319 {
1320         int i;
1321         GList *work_list;
1322
1323         g_assert (cfg->comp_done & MONO_COMP_SSA);
1324
1325         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1326
1327         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1328                 mono_ssa_create_def_use (cfg);
1329
1330         mono_ssa_copyprop (cfg);
1331
1332         work_list = NULL;
1333         for (i = 0; i < cfg->num_varinfo; i++) {
1334                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1335                 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1336         }
1337
1338         while (work_list) {
1339                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1340                 work_list = g_list_remove_link (work_list, work_list);
1341
1342                 /*
1343                  * The second part of the condition happens often when PHI nodes have their dreg
1344                  * as one of their arguments due to the fact that we use the original vars.
1345                  */
1346                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1347                         MonoInst *def = info->def;
1348
1349                         /* Eliminating FMOVE could screw up the fp stack */
1350                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1351                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1352                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1353                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1354                                 NULLIFY_INS (def);
1355                                 info->reg = -1;
1356                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1357                                 NULLIFY_INS (def);
1358                                 info->reg = -1;
1359                         } else if (MONO_IS_PHI (def)) {
1360                                 int j;
1361                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1362                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1363                                         add_to_dce_worklist (cfg, info, u, &work_list);
1364                                 }
1365                                 NULLIFY_INS (def);
1366                                 info->reg = -1;
1367                         }
1368                         else if (def->opcode == OP_NOP) {
1369                         }
1370                         //else
1371                         //mono_print_ins (def);
1372                 }
1373
1374         }
1375 }
1376
1377 #if 0
1378 void
1379 mono_ssa_strength_reduction (MonoCompile *cfg)
1380 {
1381         MonoBasicBlock *bb;
1382         int i;
1383
1384         g_assert (cfg->comp_done & MONO_COMP_SSA);
1385         g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1386         g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1387
1388         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1389                 GList *lp = bb->loop_blocks;
1390
1391                 if (lp) {
1392                         MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1393
1394                         /* we only consider loops with 2 in bblocks */
1395                         if (!h->in_count == 2)
1396                                 continue;
1397
1398                         for (i = 0; i < cfg->num_varinfo; i++) {
1399                                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1400
1401                                 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1402                                     info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1403                                         MonoInst *v = info->def->inst_i1;
1404
1405
1406                                         printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1407                                 }
1408                         }
1409                 }
1410         }
1411 }
1412 #endif
1413
1414 void
1415 mono_ssa_loop_invariant_code_motion (MonoCompile *cfg)
1416 {
1417         MonoBasicBlock *bb, *h, *idom;
1418         MonoInst *ins, *n, *tins;
1419         int i;
1420
1421         g_assert (cfg->comp_done & MONO_COMP_SSA);
1422         if (!(cfg->comp_done & MONO_COMP_LOOPS) || !(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1423                 return;
1424
1425         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1426                 GList *lp = bb->loop_blocks;
1427
1428                 if (!lp)
1429                         continue;
1430                 h = (MonoBasicBlock *)lp->data;
1431                 if (bb != h)
1432                         continue;
1433                 MONO_BB_FOR_EACH_INS_SAFE (bb, n, ins) {
1434                         /*
1435                          * Try to move instructions out of loop headers into the preceeding bblock.
1436                          */
1437                         if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS || ins->opcode == OP_AOTCONST || ins->opcode == OP_GENERIC_CLASS_INIT) {
1438                                 gboolean skip;
1439                                 int sreg;
1440
1441                                 idom = h->idom;
1442                                 /*
1443                                  * h->nesting is needed to work around:
1444                                  * http://llvm.org/bugs/show_bug.cgi?id=17868
1445                                  */
1446                                 if (!(idom && idom->last_ins && idom->last_ins->opcode == OP_BR && idom->last_ins->inst_target_bb == h && h->nesting == 1)) {
1447                                         continue;
1448                                 }
1449
1450                                 /*
1451                                  * Make sure there are no instructions with side effects before ins.
1452                                  */
1453                                 skip = FALSE;
1454                                 MONO_BB_FOR_EACH_INS (bb, tins) {
1455                                         if (tins == ins)
1456                                                 break;
1457                                         if (!MONO_INS_HAS_NO_SIDE_EFFECT (tins)) {
1458                                                 skip = TRUE;
1459                                                 break;
1460                                         }
1461                                 }
1462                                 if (skip) {
1463                                         /*
1464                                           printf ("%s\n", mono_method_full_name (cfg->method, TRUE));
1465                                           mono_print_ins (tins);
1466                                         */
1467                                         continue;
1468                                 }
1469
1470                                 /* Make sure we don't move the instruction before the def of its sreg */
1471                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS)
1472                                         sreg = ins->sreg1;
1473                                 else
1474                                         sreg = -1;
1475                                 if (sreg != -1) {
1476                                         MonoInst *tins, *var;
1477
1478                                         skip = FALSE;
1479                                         for (tins = ins->prev; tins; tins = tins->prev) {
1480                                                 const char *spec = INS_INFO (tins->opcode);
1481
1482                                                 if (tins->opcode == OP_MOVE && tins->dreg == sreg) {
1483                                                         sreg = tins->sreg1;
1484                                                 } if (spec [MONO_INST_DEST] != ' ' && tins->dreg == sreg) {
1485                                                         skip = TRUE;
1486                                                         break;
1487                                                 }
1488                                         }
1489                                         if (skip)
1490                                                 continue;
1491                                         var = get_vreg_to_inst (cfg, sreg);
1492                                         if (var && (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1493                                                 continue;
1494                                         ins->sreg1 = sreg;
1495                                 }
1496
1497                                 if (cfg->verbose_level > 1) {
1498                                         printf ("licm in BB%d on ", bb->block_num);
1499                                         mono_print_ins (ins);
1500                                 }
1501                                 //{ static int count = 0; count ++; printf ("%d\n", count); }
1502                                 MONO_REMOVE_INS (bb, ins);
1503                                 mono_bblock_insert_before_ins (idom, idom->last_ins, ins);
1504                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN)
1505                                         idom->has_array_access = TRUE;
1506                         }
1507                 }
1508         }
1509
1510         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1511         for (i = 0; i < cfg->num_varinfo; i++) {
1512                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1513                 info->def = NULL;
1514                 info->uses = NULL;
1515         }
1516 }
1517
1518 #endif /* DISABLE_JIT */