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 #include <mono/utils/mono-compiler.h>
  17
  18 #ifndef DISABLE_JIT
  19
  20 #include "mini.h"
  21 #ifdef HAVE_ALLOCA_H
  22 #include <alloca.h>
  23 #endif
  24
  25 #define CREATE_PRUNED_SSA
  26
  27 //#define DEBUG_SSA 1
  28
  29 #define NEW_PHI(cfg,dest,val) do {      \
  30         MONO_INST_NEW ((cfg), (dest), OP_PHI); \
  31         (dest)->inst_c0 = (val);                                                           \
  32         } while (0)
  33
  34 typedef struct {
  35         MonoBasicBlock *bb;
  36         MonoInst *inst;
  37 } MonoVarUsageInfo;
  38
  39 static void
  40 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
  41 {
  42         int i;
  43
  44         for (i = 0; i < bb->out_count; i++) {
  45                 if (bb->out_bb [i] == target) {
  46                         bb->out_bb [i] = bb->out_bb [--bb->out_count];
  47                         break;
  48                 }
  49         }
  50         for (i = 0; i < target->in_count; i++) {
  51                 if (target->in_bb [i] == bb) {
  52                         target->in_bb [i] = target->in_bb [--target->in_count];
  53                         break;
  54
  55                 }
  56         }
  57 }
  58
  59 static void
  60 unlink_unused_bblocks (MonoCompile *cfg)
  61 {
  62         int i, j;
  63         MonoBasicBlock *bb;
  64
  65         g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
  66
  67         if (G_UNLIKELY (cfg->verbose_level > 1))
  68                 printf ("\nUNLINK UNUSED BBLOCKS:\n");
  69
  70         for (bb = cfg->bb_entry; bb && bb->next_bb;) {
  71                 if (!(bb->next_bb->flags & BB_REACHABLE)) {
  72                         bb->next_bb = bb->next_bb->next_bb;
  73                 } else
  74                         bb = bb->next_bb;
  75         }
  76
  77         for (i = 1; i < cfg->num_bblocks; i++) {
  78                 bb = cfg->bblocks [i];
  79
  80                 if (!(bb->flags & BB_REACHABLE)) {
  81                         for (j = 0; j < bb->in_count; j++) {
  82                                 unlink_target (bb->in_bb [j], bb);
  83                         }
  84                         for (j = 0; j < bb->out_count; j++) {
  85                                 unlink_target (bb, bb->out_bb [j]);
  86                         }
  87                         if (G_UNLIKELY (cfg->verbose_level > 1))
  88                                 printf ("\tUnlinked BB%d\n", bb->block_num);
  89                 }
  90
  91         }
  92 }
  93
  94 /**
  95  * remove_bb_from_phis:
  96  *
  97  *   Remove BB from the PHI statements in TARGET.
  98  */
  99 static void
 100 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
 101 {
 102         MonoInst *ins;
 103         int i, j;
 104
 105         for (i = 0; i < target->in_count; i++) {
 106                 if (target->in_bb [i] == bb) {
 107                         break;
 108                 }
 109         }
 110         g_assert (i < target->in_count);
 111
 112         for (ins = target->code; ins; ins = ins->next) {
 113                 if (MONO_IS_PHI (ins)) {
 114                         for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
 115                                 ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
 116                         ins->inst_phi_args [0] --;
 117                 }
 118                 else
 119                         break;
 120         }
 121 }
 122
 123 static inline int
 124 op_phi_to_move (int opcode)
 125 {
 126         switch (opcode) {
 127         case OP_PHI:
 128                 return OP_MOVE;
 129         case OP_FPHI:
 130                 return OP_FMOVE;
 131         case OP_VPHI:
 132                 return OP_VMOVE;
 133         case OP_XPHI:
 134                 return OP_XMOVE;
 135         default:
 136                 g_assert_not_reached ();
 137         }
 138
 139         return -1;
 140 }
 141
 142 static inline void
 143 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
 144 {
 145         MonoMethodVar *info;
 146         MonoVarUsageInfo *ui = (MonoVarUsageInfo *)mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
 147
 148         info = MONO_VARINFO (cfg, var->inst_c0);
 149
 150         ui->bb = bb;
 151         ui->inst = ins;
 152         info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
 153 }
 154
 155 typedef struct {
 156         MonoInst *var;
 157         int idx;
 158 } RenameInfo;
 159
 160 /**
 161  * mono_ssa_rename_vars:
 162  *
 163  *  Implement renaming of SSA variables. Also compute def-use information in parallel.
 164  * @stack_history points to an area of memory which can be used for storing changes
 165  * made to the stack, so they can be reverted later.
 166  */
 167 static void
 168 mono_ssa_rename_vars (MonoCompile *cfg, int max_vars, MonoBasicBlock *bb, gboolean *originals_used, MonoInst **stack,   guint32 *lvreg_stack, gboolean *lvreg_defined, RenameInfo *stack_history, int stack_history_size)
 169 {
 170         MonoInst *ins, *new_var;
 171         int i, j, idx;
 172         GSList *tmp;
 173         int stack_history_len = 0;
 174
 175         if (cfg->verbose_level >= 4)
 176                 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
 177
 178         /* First pass: Create new vars */
 179         for (ins = bb->code; ins; ins = ins->next) {
 180                 const char *spec = INS_INFO (ins->opcode);
 181                 int num_sregs;
 182                 int sregs [MONO_MAX_SRC_REGS];
 183
 184 #ifdef DEBUG_SSA
 185                 printf ("\tProcessing "); mono_print_ins (ins);
 186 #endif
 187                 if (ins->opcode == OP_NOP)
 188                         continue;
 189
 190                 /* SREGs */
 191                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 192                 for (i = 0; i < num_sregs; ++i) {
 193                         if (spec [MONO_INST_SRC1 + i] != ' ') {
 194                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 195                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 196                                         int idx = var->inst_c0;
 197                                         if (stack [idx]) {
 198                                                 if (var->opcode != OP_ARG)
 199                                                         g_assert (stack [idx]);
 200                                                 sregs [i] = stack [idx]->dreg;
 201                                                 record_use (cfg, stack [idx], bb, ins);
 202                                         }
 203                                         else
 204                                                 record_use (cfg, var, bb, ins);
 205                                 }
 206                                 else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
 207                                         sregs [i] = lvreg_stack [sregs [i]];
 208                         }
 209                 }
 210                 mono_inst_set_src_registers (ins, sregs);
 211
 212                 if (MONO_IS_STORE_MEMBASE (ins)) {
 213                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 214                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 215                                 int idx = var->inst_c0;
 216                                 if (stack [idx]) {
 217                                         if (var->opcode != OP_ARG)
 218                                                 g_assert (stack [idx]);
 219                                         ins->dreg = stack [idx]->dreg;
 220                                         record_use (cfg, stack [idx], bb, ins);
 221                                 }
 222                                 else
 223                                         record_use (cfg, var, bb, ins);
 224                         }
 225                         else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
 226                                 ins->dreg = lvreg_stack [ins->dreg];
 227                 }
 228
 229                 /* DREG */
 230                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 231                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 232                         MonoMethodVar *info;
 233
 234                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 235                                 idx = var->inst_c0;
 236                                 g_assert (idx < max_vars);
 237
 238                                 if (var->opcode == OP_ARG)
 239                                         originals_used [idx] = TRUE;
 240
 241                                 /* FIXME: */
 242                                 g_assert (stack_history_len < stack_history_size);
 243                                 stack_history [stack_history_len].var = stack [idx];
 244                                 stack_history [stack_history_len].idx = idx;
 245                                 stack_history_len ++;
 246
 247                                 if (originals_used [idx]) {
 248                                         new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
 249                                         new_var->flags = var->flags;
 250                                         MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
 251
 252                                         if (cfg->verbose_level >= 4)
 253                                                 printf ("  R%d -> R%d\n", var->dreg, new_var->dreg);
 254
 255                                         stack [idx] = new_var;
 256
 257                                         ins->dreg = new_var->dreg;
 258                                         var = new_var;
 259                                 }
 260                                 else {
 261                                         stack [idx] = var;
 262                                         originals_used [idx] = TRUE;
 263                                 }
 264
 265                                 info = MONO_VARINFO (cfg, var->inst_c0);
 266                                 info->def = ins;
 267                                 info->def_bb = bb;
 268                         }
 269                         else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
 270                                 /* Perform renaming for local vregs */
 271                                 lvreg_stack [ins->dreg] = vreg_is_ref (cfg, ins->dreg) ? mono_alloc_ireg_ref (cfg) : mono_alloc_preg (cfg);
 272                                 ins->dreg = lvreg_stack [ins->dreg];
 273                         }
 274                         else
 275                                 lvreg_defined [ins->dreg] = TRUE;
 276                 }
 277
 278 #ifdef DEBUG_SSA
 279                 printf ("\tAfter processing "); mono_print_ins (ins);
 280 #endif
 281
 282         }
 283
 284         /* Rename PHI arguments in succeeding bblocks */
 285         for (i = 0; i < bb->out_count; i++) {
 286                 MonoBasicBlock *n = bb->out_bb [i];
 287
 288                 for (j = 0; j < n->in_count; j++)
 289                         if (n->in_bb [j] == bb)
 290                                 break;
 291
 292                 for (ins = n->code; ins; ins = ins->next) {
 293                         if (MONO_IS_PHI (ins)) {
 294                                 idx = ins->inst_c0;
 295                                 if (stack [idx])
 296                                         new_var = stack [idx];
 297                                 else
 298                                         new_var = cfg->varinfo [idx];
 299 #ifdef DEBUG_SSA
 300                                 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
 301 #endif
 302                                 ins->inst_phi_args [j + 1] = new_var->dreg;
 303                                 record_use (cfg,  new_var, n, ins);
 304                                 if (G_UNLIKELY (cfg->verbose_level >= 4))
 305                                         printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
 306                         }
 307                         else
 308                                 /* The phi nodes are at the beginning of the bblock */
 309                                 break;
 310                 }
 311         }
 312
 313         if (bb->dominated) {
 314                 for (tmp = bb->dominated; tmp; tmp = tmp->next) {
 315                         mono_ssa_rename_vars (cfg, max_vars, (MonoBasicBlock *)tmp->data, originals_used, stack, lvreg_stack, lvreg_defined, stack_history + stack_history_len, stack_history_size - stack_history_len);
 316                 }
 317         }
 318
 319         /* Restore stack */
 320         for (i = stack_history_len - 1; i >= 0; i--) {
 321                 stack [stack_history [i].idx] = stack_history [i].var;
 322         }
 323
 324         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 325 }
 326
 327 void
 328 mono_ssa_compute (MonoCompile *cfg)
 329 {
 330         int i, j, idx, bitsize;
 331         MonoBitSet *set;
 332         MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
 333         MonoInst *ins, **stack;
 334         guint8 *buf, *buf_start;
 335         RenameInfo *stack_history;
 336         int stack_history_size;
 337         gboolean *originals;
 338         guint32 *lvreg_stack;
 339         gboolean *lvreg_defined;
 340
 341         g_assert (!(cfg->comp_done & MONO_COMP_SSA));
 342
 343         g_assert (!cfg->disable_ssa);
 344
 345         if (cfg->verbose_level >= 4)
 346                 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
 347
 348 #ifdef CREATE_PRUNED_SSA
 349         /* we need liveness for pruned SSA */
 350         if (!(cfg->comp_done & MONO_COMP_LIVENESS))
 351                 mono_analyze_liveness (cfg);
 352 #endif
 353
 354         mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
 355
 356         bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
 357         buf = buf_start = (guint8 *)g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
 358
 359         for (i = 0; i < cfg->num_varinfo; ++i) {
 360                 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
 361                 buf += bitsize;
 362                 vinfo [i].idx = i;
 363                 /* implicit reference at start */
 364                 if (cfg->varinfo [i]->opcode == OP_ARG)
 365                         mono_bitset_set_fast (vinfo [i].def_in, 0);
 366         }
 367
 368         for (i = 0; i < cfg->num_bblocks; ++i) {
 369                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 370                         if (ins->opcode == OP_NOP)
 371                                 continue;
 372
 373                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 374                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 375                         }
 376                 }
 377         }
 378
 379         /* insert phi functions */
 380         for (i = 0; i < cfg->num_varinfo; ++i) {
 381                 MonoInst *var = cfg->varinfo [i];
 382
 383 #if SIZEOF_REGISTER == 4
 384                 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
 385                         continue;
 386 #endif
 387                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 388                         continue;
 389
 390                 /* Most variables have only one definition */
 391                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 392                         continue;
 393
 394                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 395
 396                 if (cfg->verbose_level >= 4) {
 397                         if (mono_bitset_count (set) > 0) {
 398                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 399                                 mono_blockset_print (cfg, set, "", -1);
 400                         }
 401                 }
 402
 403                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 404                         MonoBasicBlock *bb = cfg->bblocks [idx];
 405
 406                         /* fixme: create pruned SSA? we would need liveness information for that */
 407
 408                         if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
 409                                 continue;
 410
 411                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 412                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 413                                 continue;
 414                         }
 415
 416                         NEW_PHI (cfg, ins, i);
 417
 418                         switch (var->type) {
 419                         case STACK_I4:
 420                         case STACK_I8:
 421                         case STACK_PTR:
 422                         case STACK_MP:
 423                         case STACK_OBJ:
 424                                 ins->opcode = OP_PHI;
 425                                 break;
 426                         case STACK_R8:
 427                                 ins->opcode = OP_FPHI;
 428                                 break;
 429                         case STACK_VTYPE:
 430                                 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
 431                                 break;
 432                         }
 433
 434                         if (var->inst_vtype->byref)
 435                                 ins->klass = mono_defaults.int_class;
 436                         else
 437                                 ins->klass = var->klass;
 438
 439                         ins->inst_phi_args = (int *)mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 440                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 441
 442                         /* For debugging */
 443                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 444                                 ins->inst_phi_args [j + 1] = -1;
 445
 446                         ins->dreg = cfg->varinfo [i]->dreg;
 447
 448                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 449
 450 #ifdef DEBUG_SSA
 451                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 452 #endif
 453                 }
 454         }
 455
 456         /* free the stuff */
 457         g_free (vinfo);
 458         g_free (buf_start);
 459
 460         /* Renaming phase */
 461
 462         stack = (MonoInst **)alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 463         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 464
 465         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 466         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 467         stack_history_size = 10240;
 468         stack_history = g_new (RenameInfo, stack_history_size);
 469         originals = g_new0 (gboolean, cfg->num_varinfo);
 470         mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 471         g_free (stack_history);
 472         g_free (originals);
 473         g_free (lvreg_stack);
 474         g_free (lvreg_defined);
 475
 476         if (cfg->verbose_level >= 4)
 477                 printf ("\nEND COMPUTE SSA.\n\n");
 478
 479         cfg->comp_done |= MONO_COMP_SSA;
 480 }
 481
 482 /*
 483  * mono_ssa_remove_gsharedvt:
 484  *
 485  *   Same as mono_ssa_remove, but only remove phi nodes for gsharedvt variables.
 486  */
 487 void
 488 mono_ssa_remove_gsharedvt (MonoCompile *cfg)
 489 {
 490         MonoInst *ins, *var, *move;
 491         int i, j, first;
 492
 493         /*
 494          * When compiling gsharedvt code, we need to get rid of the VPHI instructions,
 495          * since they cannot be handled later in the llvm backend.
 496          */
 497         g_assert (cfg->comp_done & MONO_COMP_SSA);
 498
 499         for (i = 0; i < cfg->num_bblocks; ++i) {
 500                 MonoBasicBlock *bb = cfg->bblocks [i];
 501
 502                 if (cfg->verbose_level >= 4)
 503                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 504
 505                 for (ins = bb->code; ins; ins = ins->next) {
 506                         if (!(MONO_IS_PHI (ins) && ins->opcode == OP_VPHI && mini_is_gsharedvt_variable_type (&ins->klass->byval_arg)))
 507                                 continue;
 508
 509                         g_assert (ins->inst_phi_args [0] == bb->in_count);
 510                         var = get_vreg_to_inst (cfg, ins->dreg);
 511
 512                         /* Check for PHI nodes where all the inputs are the same */
 513                         first = ins->inst_phi_args [1];
 514
 515                         for (j = 1; j < bb->in_count; ++j)
 516                                 if (first != ins->inst_phi_args [j + 1])
 517                                         break;
 518
 519                         if ((bb->in_count > 1) && (j == bb->in_count)) {
 520                                 ins->opcode = op_phi_to_move (ins->opcode);
 521                                 if (ins->opcode == OP_VMOVE)
 522                                         g_assert (ins->klass);
 523                                 ins->sreg1 = first;
 524                         } else {
 525                                 for (j = 0; j < bb->in_count; j++) {
 526                                         MonoBasicBlock *pred = bb->in_bb [j];
 527                                         int sreg = ins->inst_phi_args [j + 1];
 528
 529                                         if (cfg->verbose_level >= 4)
 530                                                 printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 531                                         if (var->dreg != sreg) {
 532                                                 MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 533                                                 if (move->opcode == OP_VMOVE) {
 534                                                         g_assert (ins->klass);
 535                                                         move->klass = ins->klass;
 536                                                 }
 537                                                 move->dreg = var->dreg;
 538                                                 move->sreg1 = sreg;
 539                                                 mono_add_ins_to_end (pred, move);
 540                                         }
 541                                 }
 542
 543                                 NULLIFY_INS (ins);
 544                         }
 545                 }
 546         }
 547 }
 548
 549 void
 550 mono_ssa_remove (MonoCompile *cfg)
 551 {
 552         MonoInst *ins, *var, *move;
 553         int bbindex, i, j, first;
 554
 555         g_assert (cfg->comp_done & MONO_COMP_SSA);
 556
 557         for (i = 0; i < cfg->num_bblocks; ++i) {
 558                 MonoBasicBlock *bb = cfg->bblocks [i];
 559
 560                 if (cfg->verbose_level >= 4)
 561                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 562
 563                 for (ins = bb->code; ins; ins = ins->next) {
 564                         if (MONO_IS_PHI (ins)) {
 565                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 566                                 var = get_vreg_to_inst (cfg, ins->dreg);
 567
 568                                 /* Check for PHI nodes where all the inputs are the same */
 569                                 first = ins->inst_phi_args [1];
 570
 571                                 for (j = 1; j < bb->in_count; ++j)
 572                                         if (first != ins->inst_phi_args [j + 1])
 573                                                 break;
 574
 575                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 576                                         ins->opcode = op_phi_to_move (ins->opcode);
 577                                         if (ins->opcode == OP_VMOVE)
 578                                                 g_assert (ins->klass);
 579                                         ins->sreg1 = first;
 580                                 } else {
 581                                         for (j = 0; j < bb->in_count; j++) {
 582                                                 MonoBasicBlock *pred = bb->in_bb [j];
 583                                                 int sreg = ins->inst_phi_args [j + 1];
 584
 585                                                 if (cfg->verbose_level >= 4)
 586                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 587                                                 if (var->dreg != sreg) {
 588                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 589                                                         if (move->opcode == OP_VMOVE) {
 590                                                                 g_assert (ins->klass);
 591                                                                 move->klass = ins->klass;
 592                                                         }
 593                                                         move->dreg = var->dreg;
 594                                                         move->sreg1 = sreg;
 595                                                         mono_add_ins_to_end (pred, move);
 596                                                 }
 597                                         }
 598
 599                                         NULLIFY_INS (ins);
 600                                 }
 601                         }
 602                 }
 603         }
 604
 605         if (cfg->verbose_level >= 4) {
 606                 for (i = 0; i < cfg->num_bblocks; ++i) {
 607                         MonoBasicBlock *bb = cfg->bblocks [i];
 608
 609                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 610                 }
 611         }
 612
 613         /*
 614          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 615          * the variables if possible. Since the newly introduced SSA variables don't
 616          * have overlapping live ranges (because we don't do agressive optimization), we
 617          * can coalesce them into the original variable.
 618          */
 619
 620         for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
 621                 MonoBasicBlock *bb = cfg->bblocks [bbindex];
 622
 623                 for (ins = bb->code; ins; ins = ins->next) {
 624                         const char *spec = INS_INFO (ins->opcode);
 625                         int num_sregs;
 626                         int sregs [MONO_MAX_SRC_REGS];
 627
 628                         if (ins->opcode == OP_NOP)
 629                                 continue;
 630
 631                         if (spec [MONO_INST_DEST] != ' ') {
 632                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 633
 634                                 if (var) {
 635                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 636
 637                                         /*
 638                                          * The third condition avoids coalescing with variables eliminated
 639                                          * during deadce.
 640                                          */
 641                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 642                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 643                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 644                                         }
 645                                 }
 646                         }
 647
 648                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 649                         for (i = 0; i < num_sregs; ++i) {
 650                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 651
 652                                 if (var) {
 653                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 654
 655                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 656                                                 printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
 657                                                 sregs [i] = cfg->varinfo [vmv->reg]->dreg;
 658                                         }
 659                                 }
 660                         }
 661                         mono_inst_set_src_registers (ins, sregs);
 662                 }
 663         }
 664
 665         for (i = 0; i < cfg->num_varinfo; ++i) {
 666                 MONO_VARINFO (cfg, i)->reg = -1;
 667         }
 668
 669         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 670                 unlink_unused_bblocks (cfg);
 671
 672         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 673
 674         cfg->comp_done &= ~MONO_COMP_SSA;
 675 }
 676
 677 static void
 678 mono_ssa_create_def_use (MonoCompile *cfg)
 679 {
 680         MonoBasicBlock *bb;
 681         MonoInst *ins;
 682         int i;
 683
 684         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 685
 686         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 687                 for (ins = bb->code; ins; ins = ins->next) {
 688                         const char *spec = INS_INFO (ins->opcode);
 689                         MonoMethodVar *info;
 690                         int num_sregs;
 691                         int sregs [MONO_MAX_SRC_REGS];
 692
 693                         if (ins->opcode == OP_NOP)
 694                                 continue;
 695
 696                         /* SREGs */
 697                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 698                         for (i = 0; i < num_sregs; ++i) {
 699                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 700                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 701                                         record_use (cfg, var, bb, ins);
 702                         }
 703
 704                         if (MONO_IS_STORE_MEMBASE (ins)) {
 705                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 706                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 707                                         record_use (cfg, var, bb, ins);
 708                         }
 709
 710                         if (MONO_IS_PHI (ins)) {
 711                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 712                                         g_assert (ins->inst_phi_args [i] != -1);
 713                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 714                                 }
 715                         }
 716
 717                         /* DREG */
 718                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 719                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 720
 721                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 722                                         info = MONO_VARINFO (cfg, var->inst_c0);
 723                                         info->def = ins;
 724                                         info->def_bb = bb;
 725                                 }
 726                         }
 727                 }
 728         }
 729
 730         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 731 }
 732
 733 static void
 734 mono_ssa_copyprop (MonoCompile *cfg)
 735 {
 736         int i, index;
 737         GList *l;
 738
 739         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 740
 741         for (index = 0; index < cfg->num_varinfo; ++index) {
 742                 MonoInst *var = cfg->varinfo [index];
 743                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 744
 745                 if (info->def && (MONO_IS_MOVE (info->def))) {
 746                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 747
 748                         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))) {
 749                                 /* Rewrite all uses of var to be uses of var2 */
 750                                 int dreg = var->dreg;
 751                                 int sreg1 = var2->dreg;
 752
 753                                 l = info->uses;
 754                                 while (l) {
 755                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 756                                         MonoInst *ins = u->inst;
 757                                         GList *next = l->next;
 758                                         int num_sregs;
 759                                         int sregs [MONO_MAX_SRC_REGS];
 760
 761                                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 762                                         for (i = 0; i < num_sregs; ++i) {
 763                                                 if (sregs [i] == dreg)
 764                                                         break;
 765                                         }
 766                                         if (i < num_sregs) {
 767                                                 g_assert (sregs [i] == dreg);
 768                                                 sregs [i] = sreg1;
 769                                                 mono_inst_set_src_registers (ins, sregs);
 770                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 771                                                 ins->dreg = sreg1;
 772                                         } else if (MONO_IS_PHI (ins)) {
 773                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 774                                                         int sreg = ins->inst_phi_args [i];
 775                                                         if (sreg == var->dreg)
 776                                                                 break;
 777                                                 }
 778                                                 g_assert (i > 0);
 779                                                 ins->inst_phi_args [i] = sreg1;
 780                                         }
 781                                         else
 782                                                 g_assert_not_reached ();
 783
 784                                         record_use (cfg, var2, u->bb, ins);
 785
 786                                         l = next;
 787                                 }
 788
 789                                 info->uses = NULL;
 790                         }
 791                 }
 792         }
 793
 794         if (cfg->verbose_level >= 4) {
 795                 MonoBasicBlock *bb;
 796
 797                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 798                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 799         }
 800 }
 801
 802 static int
 803 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 804 {
 805         MonoInst *args [MONO_MAX_SRC_REGS];
 806         int rs [MONO_MAX_SRC_REGS];
 807         MonoInst *c0;
 808         gboolean const_args = TRUE;
 809         const char *spec = INS_INFO (ins->opcode);
 810         int num_sregs, i;
 811         int sregs [MONO_MAX_SRC_REGS];
 812
 813         /* Short-circuit this */
 814         if (ins->opcode == OP_ICONST) {
 815                 *res = ins;
 816                 return 1;
 817         }
 818
 819         if (ins->opcode == OP_NOP)
 820                 return 2;
 821
 822         num_sregs = mono_inst_get_src_registers (ins, sregs);
 823         for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
 824                 args [i] = NULL;
 825         for (i = 0; i < num_sregs; ++i) {
 826                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 827
 828                 rs [i] = 2;
 829                 args [i] = carray [sregs [i]];
 830                 if (args [i])
 831                         rs [i] = 1;
 832                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 833                         rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 834                 if (rs [i] != 1)
 835                         const_args = FALSE;
 836         }
 837
 838         c0 = NULL;
 839
 840         if (num_sregs > 0 && const_args) {
 841                 g_assert (num_sregs <= 2);
 842                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 843                         // Cached value
 844                         *res = carray [ins->dreg];
 845                         return 1;
 846                 }
 847                 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
 848                 if (c0) {
 849                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 850                                 printf ("\t cfold -> ");
 851                                 mono_print_ins (c0);
 852                         }
 853                         *res = c0;
 854                         return 1;
 855                 }
 856                 else
 857                         /* Can't cfold this ins */
 858                         return 2;
 859         }
 860
 861         if (num_sregs == 0)
 862                 return 2;
 863         for (i = 0; i < num_sregs; ++i) {
 864                 if (rs [i] == 2)
 865                         return 2;
 866         }
 867         return 0;
 868 }
 869
 870 static inline void
 871 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 872 {
 873         if (info->cpstate >= state)
 874                 return;
 875
 876         info->cpstate = state;
 877
 878         if (G_UNLIKELY (cfg->verbose_level > 1))
 879                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 880
 881         if (state == 1)
 882                 g_assert (c0);
 883
 884         carray [cfg->varinfo [info->idx]->dreg] = c0;
 885
 886         if (!g_list_find (*cvars, info)) {
 887                 *cvars = g_list_prepend (*cvars, info);
 888         }
 889 }
 890
 891 static inline void
 892 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 893 {
 894         if (G_UNLIKELY (cfg->verbose_level > 1))
 895                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 896
 897     if (!(bb->flags &  BB_REACHABLE)) {
 898             bb->flags |= BB_REACHABLE;
 899                 *bblist = g_list_prepend (*bblist, bb);
 900         }
 901 }
 902
 903 static void
 904 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 905 {
 906         const char *spec = INS_INFO (ins->opcode);
 907
 908         if (ins->opcode == OP_NOP)
 909                 return;
 910
 911         if (cfg->verbose_level > 1)
 912                 mono_print_ins (ins);
 913
 914         /* FIXME: Support longs/floats */
 915         /* FIXME: Work on vregs as well */
 916
 917         if (MONO_IS_PHI (ins)) {
 918                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 919                 MonoInst *c0 = NULL;
 920                 int j;
 921
 922                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 923                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 924                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 925                         MonoInst *src = mv->def;
 926
 927                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 928                                 continue;
 929
 930                         if (!mv->def || !src || mv->cpstate == 2) {
 931                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 932                                 break;
 933                         }
 934
 935                         if (mv->cpstate == 0)
 936                                 continue;
 937
 938                         g_assert (carray [var->dreg]);
 939
 940                         if (!c0)
 941                                 c0 = carray [var->dreg];
 942
 943                         /* FIXME: */
 944                         if (c0->opcode != OP_ICONST) {
 945                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 946                                 break;
 947                         }
 948
 949                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 950                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 951                                 break;
 952                         }
 953                 }
 954
 955                 if (c0 && info->cpstate < 1) {
 956                         change_varstate (cfg, cvars, info, 1, c0, carray);
 957
 958                         g_assert (c0->opcode == OP_ICONST);
 959                 }
 960         }
 961         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 962                 MonoInst *var, *c0;
 963                 int state;
 964
 965                 if (spec [MONO_INST_DEST] !=  ' ')
 966                         var = get_vreg_to_inst (cfg, ins->dreg);
 967                 else
 968                         var = NULL;
 969
 970                 c0 = NULL;
 971                 state = evaluate_ins (cfg, ins, &c0, carray);
 972
 973                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 974                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 975
 976                         if (info->cpstate < 2) {
 977                                 if (state == 1)
 978                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 979                                 else if (state == 2)
 980                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 981                         }
 982                 }
 983                 else if (!var && (ins->dreg != -1)) {
 984                         /*
 985                          * We don't record def-use information for local vregs since it would be
 986                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 987                          * the same bblock, so they will be examined after the definition.
 988                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 989                          */
 990                         if (c0) {
 991                                 carray [ins->dreg] = c0;
 992                         } else {
 993                                 if (carray [ins->dreg]) {
 994                                         /*
 995                                          * The state of the vreg changed from constant to non-constant
 996                                          * -> need to rescan the whole bblock.
 997                                          */
 998                                         carray [ins->dreg] = NULL;
 999                                         /* FIXME: Speed this up */
1000
1001                                         if (!g_list_find (*bblist, bb))
1002                                                 *bblist = g_list_prepend (*bblist, bb);
1003                                 }
1004                         }
1005                 }
1006
1007                 if (MONO_IS_JUMP_TABLE (ins)) {
1008                         int i;
1009                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1010
1011                         if (!ins->next || ins->next->opcode != OP_PADD) {
1012                                 /* The PADD was optimized away */
1013                                 /* FIXME: handle this as well */
1014                                 for (i = 0; i < table->table_size; i++)
1015                                         if (table->table [i])
1016                                                 add_cprop_bb (cfg, table->table [i], bblist);
1017                                 return;
1018                         }
1019
1020                         g_assert (ins->next->opcode == OP_PADD);
1021                         g_assert (ins->next->sreg1 == ins->dreg);
1022
1023                         if (carray [ins->next->sreg2]) {
1024 #if SIZEOF_REGISTER == 8
1025                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1026 #else
1027                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1028 #endif
1029                                 if ((idx < 0) || (idx >= table->table_size))
1030                                         /* Out-of-range, no branch is executed */
1031                                         return;
1032                                 else
1033                                         if (table->table [idx])
1034                                                 add_cprop_bb (cfg, table->table [idx], bblist);
1035                         }
1036                         else {
1037                                 for (i = 0; i < table->table_size; i++)
1038                                         if (table->table [i])
1039                                                 add_cprop_bb (cfg, table->table [i], bblist);
1040                         }
1041                 }
1042
1043                 if (ins->opcode == OP_SWITCH) {
1044                         int i;
1045                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)ins->inst_p0;
1046
1047                         for (i = 0; i < table->table_size; i++)
1048                                 if (table->table [i])
1049                                         add_cprop_bb (cfg, table->table [i], bblist);
1050                 }
1051
1052                 /* Handle COMPARE+BRCOND pairs */
1053                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
1054                         if (c0) {
1055                                 g_assert (c0->opcode == OP_ICONST);
1056
1057                                 if (c0->inst_c0)
1058                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
1059                                 else
1060                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
1061                         }
1062                         else {
1063                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1064                         }
1065
1066                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1067                 }
1068         } else if (ins->opcode == OP_BR) {
1069                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1070         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1071                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1072                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1073                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1074                         if (ins->inst_false_bb)
1075                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1076         } else {
1077                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1078                         if (ins->inst_false_bb)
1079                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1080                 }
1081         }
1082 }
1083
1084 /**
1085  * fold_ins:
1086  *
1087  *   Replace INS with its constant value, if it exists
1088  */
1089 static void
1090 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1091 {
1092         const char *spec = INS_INFO (ins->opcode);
1093         int opcode2;
1094         int num_sregs = mono_inst_get_num_src_registers (ins);
1095
1096         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1097                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1098                         /* Perform constant folding */
1099                         /* FIXME: */
1100                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1101                         ins->opcode = OP_ICONST;
1102                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1103                         MONO_INST_NULLIFY_SREGS (ins);
1104                 } else if (num_sregs == 2 && carray [ins->sreg2]) {
1105                         /* Perform op->op_imm conversion */
1106                         opcode2 = mono_op_to_op_imm (ins->opcode);
1107                         if (opcode2 != -1) {
1108                                 ins->opcode = opcode2;
1109                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1110                                 ins->sreg2 = -1;
1111
1112                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1113                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1114                         }
1115                 } else {
1116                         /* FIXME: Handle 3 op insns */
1117                 }
1118
1119                 if (MONO_IS_JUMP_TABLE (ins)) {
1120                         int i;
1121                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1122
1123                         if (!ins->next || ins->next->opcode != OP_PADD) {
1124                                 /* The PADD was optimized away */
1125                                 /* FIXME: handle this as well */
1126                                 return;
1127                         }
1128
1129                         g_assert (ins->next->opcode == OP_PADD);
1130                         g_assert (ins->next->sreg1 == ins->dreg);
1131                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1132
1133                         if (carray [ins->next->sreg2]) {
1134                                 /* Convert to a simple branch */
1135 #if SIZEOF_REGISTER == 8
1136                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1137 #else
1138                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1139 #endif
1140
1141                                 if (!((idx >= 0) && (idx < table->table_size))) {
1142                                         /* Out of range, eliminate the whole switch */
1143                                         for (i = 0; i < table->table_size; ++i) {
1144                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1145                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1146                                         }
1147
1148                                         NULLIFY_INS (ins);
1149                                         NULLIFY_INS (ins->next);
1150                                         NULLIFY_INS (ins->next->next);
1151                                         if (ins->next->next->next)
1152                                                 NULLIFY_INS (ins->next->next->next);
1153
1154                                         return;
1155                                 }
1156
1157                                 if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
1158                                         /* A one-way switch which got optimized away */
1159                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1160                                                 printf ("\tNo cfold on ");
1161                                                 mono_print_ins (ins);
1162                                         }
1163                                         return;
1164                                 }
1165
1166                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1167                                         printf ("\tcfold on ");
1168                                         mono_print_ins (ins);
1169                                 }
1170
1171                                 /* Unlink target bblocks */
1172                                 for (i = 0; i < table->table_size; ++i) {
1173                                         if (table->table [i] != table->table [idx]) {
1174                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1175                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1176                                         }
1177                                 }
1178
1179                                 /* Change the OP_BR_REG to a simple branch */
1180                                 ins->next->next->next->opcode = OP_BR;
1181                                 ins->next->next->next->inst_target_bb = table->table [idx];
1182                                 ins->next->next->next->sreg1 = -1;
1183
1184                                 /* Nullify the other instructions */
1185                                 NULLIFY_INS (ins);
1186                                 NULLIFY_INS (ins->next);
1187                                 NULLIFY_INS (ins->next->next);
1188                         }
1189                 }
1190         }
1191         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1192                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1193                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1194                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1195                         ins->opcode = OP_BR;
1196                         ins->inst_target_bb = ins->inst_true_bb;
1197                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1198                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1199                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1200                         ins->opcode = OP_BR;
1201                         ins->inst_target_bb = ins->inst_false_bb;
1202                 }
1203         }
1204 }
1205
1206 void
1207 mono_ssa_cprop (MonoCompile *cfg)
1208 {
1209         MonoInst **carray;
1210         MonoBasicBlock *bb;
1211         GList *bblock_list, *cvars;
1212         GList *tmp;
1213         int i;
1214         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1215
1216         carray = g_new0 (MonoInst*, cfg->next_vreg);
1217
1218         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1219                 mono_ssa_create_def_use (cfg);
1220
1221         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1222         cfg->bb_entry->flags |= BB_REACHABLE;
1223
1224         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1225
1226         for (i = 0; i < cfg->num_varinfo; i++) {
1227                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1228                 if (!info->def)
1229                         info->cpstate = 2;
1230         }
1231
1232         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1233                 /*
1234                  * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1235                  * that would still allow unreachable try's to be removed.
1236                  */
1237                 if (bb->region)
1238                         add_cprop_bb (cfg, bb, &bblock_list);
1239         }
1240
1241         cvars = NULL;
1242
1243         while (bblock_list) {
1244                 MonoInst *inst;
1245
1246                 bb = (MonoBasicBlock *)bblock_list->data;
1247
1248                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1249
1250                 g_assert (bb->flags &  BB_REACHABLE);
1251
1252                 /*
1253                  * Some bblocks are linked to 2 others even through they fall through to the
1254                  * next bblock.
1255                  */
1256                 if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
1257                         for (i = 0; i < bb->out_count; ++i)
1258                                 add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
1259                 }
1260
1261                 if (cfg->verbose_level > 1)
1262                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1263
1264                 for (inst = bb->code; inst; inst = inst->next) {
1265                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1266                 }
1267
1268                 while (cvars) {
1269                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1270                         cvars = g_list_delete_link (cvars, cvars);
1271
1272                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1273                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1274                                 if (!(ui->bb->flags & BB_REACHABLE))
1275                                         continue;
1276                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1277                         }
1278                 }
1279         }
1280
1281         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1282                 MonoInst *inst;
1283                 for (inst = bb->code; inst; inst = inst->next) {
1284                         fold_ins (cfg, bb, inst, carray);
1285                 }
1286         }
1287
1288         g_free (carray);
1289
1290         cfg->comp_done |= MONO_COMP_REACHABILITY;
1291
1292         /* fixme: we should update usage infos during cprop, instead of computing it again */
1293         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1294         for (i = 0; i < cfg->num_varinfo; i++) {
1295                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1296                 info->def = NULL;
1297                 info->uses = NULL;
1298         }
1299 }
1300
1301 static inline void
1302 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1303 {
1304         GList *tmp;
1305
1306         *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1307
1308         for (tmp = use->uses; tmp; tmp = tmp->next) {
1309                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1310                 if (ui->inst == var->def) {
1311                         /* from the mempool */
1312                         use->uses = g_list_remove_link (use->uses, tmp);
1313                         break;
1314                 }
1315         }
1316 }
1317
1318 void
1319 mono_ssa_deadce (MonoCompile *cfg)
1320 {
1321         int i;
1322         GList *work_list;
1323
1324         g_assert (cfg->comp_done & MONO_COMP_SSA);
1325
1326         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1327
1328         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1329                 mono_ssa_create_def_use (cfg);
1330
1331         mono_ssa_copyprop (cfg);
1332
1333         work_list = NULL;
1334         for (i = 0; i < cfg->num_varinfo; i++) {
1335                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1336                 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1337         }
1338
1339         while (work_list) {
1340                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1341                 work_list = g_list_remove_link (work_list, work_list);
1342
1343                 /*
1344                  * The second part of the condition happens often when PHI nodes have their dreg
1345                  * as one of their arguments due to the fact that we use the original vars.
1346                  */
1347                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1348                         MonoInst *def = info->def;
1349
1350                         /* Eliminating FMOVE could screw up the fp stack */
1351                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1352                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1353                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1354                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1355                                 NULLIFY_INS (def);
1356                                 info->reg = -1;
1357                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1358                                 NULLIFY_INS (def);
1359                                 info->reg = -1;
1360                         } else if (MONO_IS_PHI (def)) {
1361                                 int j;
1362                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1363                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1364                                         add_to_dce_worklist (cfg, info, u, &work_list);
1365                                 }
1366                                 NULLIFY_INS (def);
1367                                 info->reg = -1;
1368                         }
1369                         else if (def->opcode == OP_NOP) {
1370                         }
1371                         //else
1372                         //mono_print_ins (def);
1373                 }
1374
1375         }
1376 }
1377
1378 #if 0
1379 void
1380 mono_ssa_strength_reduction (MonoCompile *cfg)
1381 {
1382         MonoBasicBlock *bb;
1383         int i;
1384
1385         g_assert (cfg->comp_done & MONO_COMP_SSA);
1386         g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1387         g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1388
1389         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1390                 GList *lp = bb->loop_blocks;
1391
1392                 if (lp) {
1393                         MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1394
1395                         /* we only consider loops with 2 in bblocks */
1396                         if (!h->in_count == 2)
1397                                 continue;
1398
1399                         for (i = 0; i < cfg->num_varinfo; i++) {
1400                                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1401
1402                                 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1403                                     info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1404                                         MonoInst *v = info->def->inst_i1;
1405
1406
1407                                         printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1408                                 }
1409                         }
1410                 }
1411         }
1412 }
1413 #endif
1414
1415 void
1416 mono_ssa_loop_invariant_code_motion (MonoCompile *cfg)
1417 {
1418         MonoBasicBlock *bb, *h, *idom;
1419         MonoInst *ins, *n, *tins;
1420         int i;
1421
1422         g_assert (cfg->comp_done & MONO_COMP_SSA);
1423         if (!(cfg->comp_done & MONO_COMP_LOOPS) || !(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1424                 return;
1425
1426         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1427                 GList *lp = bb->loop_blocks;
1428
1429                 if (!lp)
1430                         continue;
1431                 h = (MonoBasicBlock *)lp->data;
1432                 if (bb != h)
1433                         continue;
1434                 MONO_BB_FOR_EACH_INS_SAFE (bb, n, ins) {
1435                         /*
1436                          * Try to move instructions out of loop headers into the preceeding bblock.
1437                          */
1438                         if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS || ins->opcode == OP_AOTCONST || ins->opcode == OP_GENERIC_CLASS_INIT) {
1439                                 gboolean skip;
1440                                 int sreg;
1441
1442                                 idom = h->idom;
1443                                 /*
1444                                  * h->nesting is needed to work around:
1445                                  * http://llvm.org/bugs/show_bug.cgi?id=17868
1446                                  */
1447                                 if (!(idom && idom->last_ins && idom->last_ins->opcode == OP_BR && idom->last_ins->inst_target_bb == h && h->nesting == 1)) {
1448                                         continue;
1449                                 }
1450
1451                                 /*
1452                                  * Make sure there are no instructions with side effects before ins.
1453                                  */
1454                                 skip = FALSE;
1455                                 MONO_BB_FOR_EACH_INS (bb, tins) {
1456                                         if (tins == ins)
1457                                                 break;
1458                                         if (!MONO_INS_HAS_NO_SIDE_EFFECT (tins)) {
1459                                                 skip = TRUE;
1460                                                 break;
1461                                         }
1462                                 }
1463                                 if (skip) {
1464                                         /*
1465                                           printf ("%s\n", mono_method_full_name (cfg->method, TRUE));
1466                                           mono_print_ins (tins);
1467                                         */
1468                                         continue;
1469                                 }
1470
1471                                 /* Make sure we don't move the instruction before the def of its sreg */
1472                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS)
1473                                         sreg = ins->sreg1;
1474                                 else
1475                                         sreg = -1;
1476                                 if (sreg != -1) {
1477                                         MonoInst *tins, *var;
1478
1479                                         skip = FALSE;
1480                                         for (tins = ins->prev; tins; tins = tins->prev) {
1481                                                 const char *spec = INS_INFO (tins->opcode);
1482
1483                                                 if (tins->opcode == OP_MOVE && tins->dreg == sreg) {
1484                                                         sreg = tins->sreg1;
1485                                                 } if (spec [MONO_INST_DEST] != ' ' && tins->dreg == sreg) {
1486                                                         skip = TRUE;
1487                                                         break;
1488                                                 }
1489                                         }
1490                                         if (skip)
1491                                                 continue;
1492                                         var = get_vreg_to_inst (cfg, sreg);
1493                                         if (var && (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1494                                                 continue;
1495                                         ins->sreg1 = sreg;
1496                                 }
1497
1498                                 if (cfg->verbose_level > 1) {
1499                                         printf ("licm in BB%d on ", bb->block_num);
1500                                         mono_print_ins (ins);
1501                                 }
1502                                 //{ static int count = 0; count ++; printf ("%d\n", count); }
1503                                 MONO_REMOVE_INS (bb, ins);
1504                                 mono_bblock_insert_before_ins (idom, idom->last_ins, ins);
1505                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN)
1506                                         idom->has_array_access = TRUE;
1507                         }
1508                 }
1509         }
1510
1511         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1512         for (i = 0; i < cfg->num_varinfo; i++) {
1513                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1514                 info->def = NULL;
1515                 info->uses = NULL;
1516         }
1517 }
1518
1519 #else /* !DISABLE_JIT */
1520
1521 MONO_EMPTY_SOURCE_FILE (ssa);
1522
1523 #endif /* !DISABLE_JIT */