mono/mini/ssa.c

   1 /**
   2  * \file
   3  * Static single assign form support for the JIT compiler.
   4  *
   5  * Author:
   6  *    Dietmar Maurer (dietmar@ximian.com)
   7  *
   8  * (C) 2003 Ximian, Inc.
   9  * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
  10  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  11  */
  12 #include <config.h>
  13 #include <string.h>
  14 #include <mono/metadata/debug-helpers.h>
  15 #include <mono/metadata/mempool.h>
  16 #include <mono/metadata/mempool-internals.h>
  17 #include <mono/utils/mono-compiler.h>
  18
  19 #ifndef DISABLE_JIT
  20
  21 #include "mini.h"
  22 #ifdef HAVE_ALLOCA_H
  23 #include <alloca.h>
  24 #endif
  25
  26 #define CREATE_PRUNED_SSA
  27
  28 //#define DEBUG_SSA 1
  29
  30 #define NEW_PHI(cfg,dest,val) do {      \
  31         MONO_INST_NEW ((cfg), (dest), OP_PHI); \
  32         (dest)->inst_c0 = (val);                                                           \
  33         } while (0)
  34
  35 typedef struct {
  36         MonoBasicBlock *bb;
  37         MonoInst *inst;
  38 } MonoVarUsageInfo;
  39
  40 static void
  41 unlink_target (MonoBasicBlock *bb, MonoBasicBlock *target)
  42 {
  43         int i;
  44
  45         for (i = 0; i < bb->out_count; i++) {
  46                 if (bb->out_bb [i] == target) {
  47                         bb->out_bb [i] = bb->out_bb [--bb->out_count];
  48                         break;
  49                 }
  50         }
  51         for (i = 0; i < target->in_count; i++) {
  52                 if (target->in_bb [i] == bb) {
  53                         target->in_bb [i] = target->in_bb [--target->in_count];
  54                         break;
  55
  56                 }
  57         }
  58 }
  59
  60 static void
  61 unlink_unused_bblocks (MonoCompile *cfg)
  62 {
  63         int i, j;
  64         MonoBasicBlock *bb;
  65
  66         g_assert (cfg->comp_done & MONO_COMP_REACHABILITY);
  67
  68         if (G_UNLIKELY (cfg->verbose_level > 1))
  69                 printf ("\nUNLINK UNUSED BBLOCKS:\n");
  70
  71         for (bb = cfg->bb_entry; bb && bb->next_bb;) {
  72                 if (!(bb->next_bb->flags & BB_REACHABLE)) {
  73                         bb->next_bb = bb->next_bb->next_bb;
  74                 } else
  75                         bb = bb->next_bb;
  76         }
  77
  78         for (i = 1; i < cfg->num_bblocks; i++) {
  79                 bb = cfg->bblocks [i];
  80
  81                 if (!(bb->flags & BB_REACHABLE)) {
  82                         for (j = 0; j < bb->in_count; j++) {
  83                                 unlink_target (bb->in_bb [j], bb);
  84                         }
  85                         for (j = 0; j < bb->out_count; j++) {
  86                                 unlink_target (bb, bb->out_bb [j]);
  87                         }
  88                         if (G_UNLIKELY (cfg->verbose_level > 1))
  89                                 printf ("\tUnlinked BB%d\n", bb->block_num);
  90                 }
  91
  92         }
  93 }
  94
  95 /**
  96  * remove_bb_from_phis:
  97  *
  98  *   Remove BB from the PHI statements in TARGET.
  99  */
 100 static void
 101 remove_bb_from_phis (MonoCompile *cfg, MonoBasicBlock *bb, MonoBasicBlock *target)
 102 {
 103         MonoInst *ins;
 104         int i, j;
 105
 106         for (i = 0; i < target->in_count; i++) {
 107                 if (target->in_bb [i] == bb) {
 108                         break;
 109                 }
 110         }
 111         g_assert (i < target->in_count);
 112
 113         for (ins = target->code; ins; ins = ins->next) {
 114                 if (MONO_IS_PHI (ins)) {
 115                         for (j = i; j < ins->inst_phi_args [0] - 1; ++j)
 116                                 ins->inst_phi_args [j + 1] = ins->inst_phi_args [j + 2];
 117                         ins->inst_phi_args [0] --;
 118                 }
 119                 else
 120                         break;
 121         }
 122 }
 123
 124 static inline int
 125 op_phi_to_move (int opcode)
 126 {
 127         switch (opcode) {
 128         case OP_PHI:
 129                 return OP_MOVE;
 130         case OP_FPHI:
 131                 return OP_FMOVE;
 132         case OP_VPHI:
 133                 return OP_VMOVE;
 134         case OP_XPHI:
 135                 return OP_XMOVE;
 136         default:
 137                 g_assert_not_reached ();
 138         }
 139
 140         return -1;
 141 }
 142
 143 static inline void
 144 record_use (MonoCompile *cfg, MonoInst *var, MonoBasicBlock *bb, MonoInst *ins)
 145 {
 146         MonoMethodVar *info;
 147         MonoVarUsageInfo *ui = (MonoVarUsageInfo *)mono_mempool_alloc (cfg->mempool, sizeof (MonoVarUsageInfo));
 148
 149         info = MONO_VARINFO (cfg, var->inst_c0);
 150
 151         ui->bb = bb;
 152         ui->inst = ins;
 153         info->uses = g_list_prepend_mempool (cfg->mempool, info->uses, ui);
 154 }
 155
 156 typedef struct {
 157         MonoInst *var;
 158         int idx;
 159 } RenameInfo;
 160
 161 /**
 162  * mono_ssa_rename_vars:
 163  *
 164  *  Implement renaming of SSA variables. Also compute def-use information in parallel.
 165  * @stack_history points to an area of memory which can be used for storing changes
 166  * made to the stack, so they can be reverted later.
 167  */
 168 static void
 169 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)
 170 {
 171         MonoInst *ins, *new_var;
 172         int i, j, idx;
 173         GSList *tmp;
 174         int stack_history_len = 0;
 175
 176         if (cfg->verbose_level >= 4)
 177                 printf ("\nRENAME VARS BLOCK %d:\n", bb->block_num);
 178
 179         /* First pass: Create new vars */
 180         for (ins = bb->code; ins; ins = ins->next) {
 181                 const char *spec = INS_INFO (ins->opcode);
 182                 int num_sregs;
 183                 int sregs [MONO_MAX_SRC_REGS];
 184
 185 #ifdef DEBUG_SSA
 186                 printf ("\tProcessing "); mono_print_ins (ins);
 187 #endif
 188                 if (ins->opcode == OP_NOP)
 189                         continue;
 190
 191                 /* SREGs */
 192                 num_sregs = mono_inst_get_src_registers (ins, sregs);
 193                 for (i = 0; i < num_sregs; ++i) {
 194                         if (spec [MONO_INST_SRC1 + i] != ' ') {
 195                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 196                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 197                                         int idx = var->inst_c0;
 198                                         if (stack [idx]) {
 199                                                 if (var->opcode != OP_ARG)
 200                                                         g_assert (stack [idx]);
 201                                                 sregs [i] = stack [idx]->dreg;
 202                                                 record_use (cfg, stack [idx], bb, ins);
 203                                         }
 204                                         else
 205                                                 record_use (cfg, var, bb, ins);
 206                                 }
 207                                 else if (G_UNLIKELY (!var && lvreg_stack [sregs [i]]))
 208                                         sregs [i] = lvreg_stack [sregs [i]];
 209                         }
 210                 }
 211                 mono_inst_set_src_registers (ins, sregs);
 212
 213                 if (MONO_IS_STORE_MEMBASE (ins)) {
 214                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 215                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 216                                 int idx = var->inst_c0;
 217                                 if (stack [idx]) {
 218                                         if (var->opcode != OP_ARG)
 219                                                 g_assert (stack [idx]);
 220                                         ins->dreg = stack [idx]->dreg;
 221                                         record_use (cfg, stack [idx], bb, ins);
 222                                 }
 223                                 else
 224                                         record_use (cfg, var, bb, ins);
 225                         }
 226                         else if (G_UNLIKELY (!var && lvreg_stack [ins->dreg]))
 227                                 ins->dreg = lvreg_stack [ins->dreg];
 228                 }
 229
 230                 /* DREG */
 231                 if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 232                         MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 233                         MonoMethodVar *info;
 234
 235                         if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 236                                 idx = var->inst_c0;
 237                                 g_assert (idx < max_vars);
 238
 239                                 if (var->opcode == OP_ARG)
 240                                         originals_used [idx] = TRUE;
 241
 242                                 if (stack_history_len + 128 > stack_history_size) {
 243                                         stack_history_size += 1024;
 244                                         RenameInfo *new_history = mono_mempool_alloc (cfg->mempool, sizeof (RenameInfo) * stack_history_size);
 245                                         memcpy (new_history, stack_history, stack_history_len * sizeof (RenameInfo));
 246                                         stack_history = new_history;
 247                                 }
 248
 249                                 stack_history [stack_history_len].var = stack [idx];
 250                                 stack_history [stack_history_len].idx = idx;
 251                                 stack_history_len ++;
 252
 253                                 if (originals_used [idx]) {
 254                                         new_var = mono_compile_create_var (cfg, var->inst_vtype, OP_LOCAL);
 255                                         new_var->flags = var->flags;
 256                                         MONO_VARINFO (cfg, new_var->inst_c0)->reg = idx;
 257
 258                                         if (cfg->verbose_level >= 4)
 259                                                 printf ("  R%d -> R%d\n", var->dreg, new_var->dreg);
 260
 261                                         stack [idx] = new_var;
 262
 263                                         ins->dreg = new_var->dreg;
 264                                         var = new_var;
 265                                 }
 266                                 else {
 267                                         stack [idx] = var;
 268                                         originals_used [idx] = TRUE;
 269                                 }
 270
 271                                 info = MONO_VARINFO (cfg, var->inst_c0);
 272                                 info->def = ins;
 273                                 info->def_bb = bb;
 274                         }
 275                         else if (G_UNLIKELY (!var && lvreg_defined [ins->dreg] && (ins->dreg >= MONO_MAX_IREGS))) {
 276                                 /* Perform renaming for local vregs */
 277                                 lvreg_stack [ins->dreg] = vreg_is_ref (cfg, ins->dreg) ? mono_alloc_ireg_ref (cfg) : mono_alloc_preg (cfg);
 278                                 ins->dreg = lvreg_stack [ins->dreg];
 279                         }
 280                         else
 281                                 lvreg_defined [ins->dreg] = TRUE;
 282                 }
 283
 284 #ifdef DEBUG_SSA
 285                 printf ("\tAfter processing "); mono_print_ins (ins);
 286 #endif
 287
 288         }
 289
 290         /* Rename PHI arguments in succeeding bblocks */
 291         for (i = 0; i < bb->out_count; i++) {
 292                 MonoBasicBlock *n = bb->out_bb [i];
 293
 294                 for (j = 0; j < n->in_count; j++)
 295                         if (n->in_bb [j] == bb)
 296                                 break;
 297
 298                 for (ins = n->code; ins; ins = ins->next) {
 299                         if (MONO_IS_PHI (ins)) {
 300                                 idx = ins->inst_c0;
 301                                 if (stack [idx])
 302                                         new_var = stack [idx];
 303                                 else
 304                                         new_var = cfg->varinfo [idx];
 305 #ifdef DEBUG_SSA
 306                                 printf ("FOUND PHI %d (%d, %d)\n", idx, j, new_var->inst_c0);
 307 #endif
 308                                 ins->inst_phi_args [j + 1] = new_var->dreg;
 309                                 record_use (cfg,  new_var, n, ins);
 310                                 if (G_UNLIKELY (cfg->verbose_level >= 4))
 311                                         printf ("\tAdd PHI R%d <- R%d to BB%d\n", ins->dreg, new_var->dreg, n->block_num);
 312                         }
 313                         else
 314                                 /* The phi nodes are at the beginning of the bblock */
 315                                 break;
 316                 }
 317         }
 318
 319         if (bb->dominated) {
 320                 for (tmp = bb->dominated; tmp; tmp = tmp->next) {
 321                         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);
 322                 }
 323         }
 324
 325         /* Restore stack */
 326         for (i = stack_history_len - 1; i >= 0; i--) {
 327                 stack [stack_history [i].idx] = stack_history [i].var;
 328         }
 329
 330         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 331 }
 332
 333 void
 334 mono_ssa_compute (MonoCompile *cfg)
 335 {
 336         int i, j, idx, bitsize;
 337         MonoBitSet *set;
 338         MonoMethodVar *vinfo = g_new0 (MonoMethodVar, cfg->num_varinfo);
 339         MonoInst *ins, **stack;
 340         guint8 *buf, *buf_start;
 341         RenameInfo *stack_history;
 342         int stack_history_size;
 343         gboolean *originals;
 344         guint32 *lvreg_stack;
 345         gboolean *lvreg_defined;
 346
 347         g_assert (!(cfg->comp_done & MONO_COMP_SSA));
 348
 349         g_assert (!cfg->disable_ssa);
 350
 351         if (cfg->verbose_level >= 4)
 352                 printf ("\nCOMPUTE SSA %d (R%d-)\n\n", cfg->num_varinfo, cfg->next_vreg);
 353
 354 #ifdef CREATE_PRUNED_SSA
 355         /* we need liveness for pruned SSA */
 356         if (!(cfg->comp_done & MONO_COMP_LIVENESS))
 357                 mono_analyze_liveness (cfg);
 358 #endif
 359
 360         mono_compile_dominator_info (cfg, MONO_COMP_DOM | MONO_COMP_IDOM | MONO_COMP_DFRONTIER);
 361
 362         bitsize = mono_bitset_alloc_size (cfg->num_bblocks, 0);
 363         buf = buf_start = (guint8 *)g_malloc0 (mono_bitset_alloc_size (cfg->num_bblocks, 0) * cfg->num_varinfo);
 364
 365         for (i = 0; i < cfg->num_varinfo; ++i) {
 366                 vinfo [i].def_in = mono_bitset_mem_new (buf, cfg->num_bblocks, 0);
 367                 buf += bitsize;
 368                 vinfo [i].idx = i;
 369                 /* implicit reference at start */
 370                 if (cfg->varinfo [i]->opcode == OP_ARG)
 371                         mono_bitset_set_fast (vinfo [i].def_in, 0);
 372         }
 373
 374         for (i = 0; i < cfg->num_bblocks; ++i) {
 375                 MONO_BB_FOR_EACH_INS (cfg->bblocks [i], ins) {
 376                         if (ins->opcode == OP_NOP)
 377                                 continue;
 378
 379                         if (!MONO_IS_STORE_MEMBASE (ins) && get_vreg_to_inst (cfg, ins->dreg)) {
 380                                 mono_bitset_set_fast (vinfo [get_vreg_to_inst (cfg, ins->dreg)->inst_c0].def_in, i);
 381                         }
 382                 }
 383         }
 384
 385         /* insert phi functions */
 386         for (i = 0; i < cfg->num_varinfo; ++i) {
 387                 MonoInst *var = cfg->varinfo [i];
 388
 389 #if SIZEOF_REGISTER == 4
 390                 if (var->type == STACK_I8 && !COMPILE_LLVM (cfg))
 391                         continue;
 392 #endif
 393                 if (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))
 394                         continue;
 395
 396                 /* Most variables have only one definition */
 397                 if (mono_bitset_count (vinfo [i].def_in) <= 1)
 398                         continue;
 399
 400                 set = mono_compile_iterated_dfrontier (cfg, vinfo [i].def_in);
 401
 402                 if (cfg->verbose_level >= 4) {
 403                         if (mono_bitset_count (set) > 0) {
 404                                 printf ("\tR%d needs PHI functions in ", var->dreg);
 405                                 mono_blockset_print (cfg, set, "", -1);
 406                         }
 407                 }
 408
 409                 mono_bitset_foreach_bit (set, idx, cfg->num_bblocks) {
 410                         MonoBasicBlock *bb = cfg->bblocks [idx];
 411
 412                         /* fixme: create pruned SSA? we would need liveness information for that */
 413
 414                         if (bb == cfg->bb_exit && !COMPILE_LLVM (cfg))
 415                                 continue;
 416
 417                         if ((cfg->comp_done & MONO_COMP_LIVENESS) && !mono_bitset_test_fast (bb->live_in_set, i)) {
 418                                 //printf ("%d is not live in BB%d %s\n", i, bb->block_num, mono_method_full_name (cfg->method, TRUE));
 419                                 continue;
 420                         }
 421
 422                         NEW_PHI (cfg, ins, i);
 423
 424                         switch (var->type) {
 425                         case STACK_I4:
 426                         case STACK_I8:
 427                         case STACK_PTR:
 428                         case STACK_MP:
 429                         case STACK_OBJ:
 430                                 ins->opcode = OP_PHI;
 431                                 break;
 432                         case STACK_R8:
 433                                 ins->opcode = OP_FPHI;
 434                                 break;
 435                         case STACK_VTYPE:
 436                                 ins->opcode = MONO_CLASS_IS_SIMD (cfg, var->klass) ? OP_XPHI : OP_VPHI;
 437                                 break;
 438                         }
 439
 440                         if (var->inst_vtype->byref)
 441                                 ins->klass = mono_defaults.int_class;
 442                         else
 443                                 ins->klass = var->klass;
 444
 445                         ins->inst_phi_args = (int *)mono_mempool_alloc0 (cfg->mempool, sizeof (int) * (cfg->bblocks [idx]->in_count + 1));
 446                         ins->inst_phi_args [0] = cfg->bblocks [idx]->in_count;
 447
 448                         /* For debugging */
 449                         for (j = 0; j < cfg->bblocks [idx]->in_count; ++j)
 450                                 ins->inst_phi_args [j + 1] = -1;
 451
 452                         ins->dreg = cfg->varinfo [i]->dreg;
 453
 454                         mono_bblock_insert_before_ins (bb, bb->code, ins);
 455
 456 #ifdef DEBUG_SSA
 457                         printf ("ADD PHI BB%d %s\n", cfg->bblocks [idx]->block_num, mono_method_full_name (cfg->method, TRUE));
 458 #endif
 459                 }
 460         }
 461
 462         /* free the stuff */
 463         g_free (vinfo);
 464         g_free (buf_start);
 465
 466         /* Renaming phase */
 467
 468         stack = (MonoInst **)alloca (sizeof (MonoInst *) * cfg->num_varinfo);
 469         memset (stack, 0, sizeof (MonoInst *) * cfg->num_varinfo);
 470
 471         lvreg_stack = g_new0 (guint32, cfg->next_vreg);
 472         lvreg_defined = g_new0 (gboolean, cfg->next_vreg);
 473         stack_history_size = 10240;
 474         stack_history = g_new (RenameInfo, stack_history_size);
 475         originals = g_new0 (gboolean, cfg->num_varinfo);
 476         mono_ssa_rename_vars (cfg, cfg->num_varinfo, cfg->bb_entry, originals, stack, lvreg_stack, lvreg_defined, stack_history, stack_history_size);
 477         g_free (stack_history);
 478         g_free (originals);
 479         g_free (lvreg_stack);
 480         g_free (lvreg_defined);
 481
 482         if (cfg->verbose_level >= 4)
 483                 printf ("\nEND COMPUTE SSA.\n\n");
 484
 485         cfg->comp_done |= MONO_COMP_SSA;
 486 }
 487
 488 /*
 489  * mono_ssa_remove_gsharedvt:
 490  *
 491  *   Same as mono_ssa_remove, but only remove phi nodes for gsharedvt variables.
 492  */
 493 void
 494 mono_ssa_remove_gsharedvt (MonoCompile *cfg)
 495 {
 496         MonoInst *ins, *var, *move;
 497         int i, j, first;
 498
 499         /*
 500          * When compiling gsharedvt code, we need to get rid of the VPHI instructions,
 501          * since they cannot be handled later in the llvm backend.
 502          */
 503         g_assert (cfg->comp_done & MONO_COMP_SSA);
 504
 505         for (i = 0; i < cfg->num_bblocks; ++i) {
 506                 MonoBasicBlock *bb = cfg->bblocks [i];
 507
 508                 if (cfg->verbose_level >= 4)
 509                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 510
 511                 for (ins = bb->code; ins; ins = ins->next) {
 512                         if (!(MONO_IS_PHI (ins) && ins->opcode == OP_VPHI && mini_is_gsharedvt_variable_type (&ins->klass->byval_arg)))
 513                                 continue;
 514
 515                         g_assert (ins->inst_phi_args [0] == bb->in_count);
 516                         var = get_vreg_to_inst (cfg, ins->dreg);
 517
 518                         /* Check for PHI nodes where all the inputs are the same */
 519                         first = ins->inst_phi_args [1];
 520
 521                         for (j = 1; j < bb->in_count; ++j)
 522                                 if (first != ins->inst_phi_args [j + 1])
 523                                         break;
 524
 525                         if ((bb->in_count > 1) && (j == bb->in_count)) {
 526                                 ins->opcode = op_phi_to_move (ins->opcode);
 527                                 if (ins->opcode == OP_VMOVE)
 528                                         g_assert (ins->klass);
 529                                 ins->sreg1 = first;
 530                         } else {
 531                                 for (j = 0; j < bb->in_count; j++) {
 532                                         MonoBasicBlock *pred = bb->in_bb [j];
 533                                         int sreg = ins->inst_phi_args [j + 1];
 534
 535                                         if (cfg->verbose_level >= 4)
 536                                                 printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 537                                         if (var->dreg != sreg) {
 538                                                 MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 539                                                 if (move->opcode == OP_VMOVE) {
 540                                                         g_assert (ins->klass);
 541                                                         move->klass = ins->klass;
 542                                                 }
 543                                                 move->dreg = var->dreg;
 544                                                 move->sreg1 = sreg;
 545                                                 mono_add_ins_to_end (pred, move);
 546                                         }
 547                                 }
 548
 549                                 NULLIFY_INS (ins);
 550                         }
 551                 }
 552         }
 553 }
 554
 555 void
 556 mono_ssa_remove (MonoCompile *cfg)
 557 {
 558         MonoInst *ins, *var, *move;
 559         int bbindex, i, j, first;
 560
 561         g_assert (cfg->comp_done & MONO_COMP_SSA);
 562
 563         for (i = 0; i < cfg->num_bblocks; ++i) {
 564                 MonoBasicBlock *bb = cfg->bblocks [i];
 565
 566                 if (cfg->verbose_level >= 4)
 567                         printf ("\nREMOVE SSA %d:\n", bb->block_num);
 568
 569                 for (ins = bb->code; ins; ins = ins->next) {
 570                         if (MONO_IS_PHI (ins)) {
 571                                 g_assert (ins->inst_phi_args [0] == bb->in_count);
 572                                 var = get_vreg_to_inst (cfg, ins->dreg);
 573
 574                                 /* Check for PHI nodes where all the inputs are the same */
 575                                 first = ins->inst_phi_args [1];
 576
 577                                 for (j = 1; j < bb->in_count; ++j)
 578                                         if (first != ins->inst_phi_args [j + 1])
 579                                                 break;
 580
 581                                 if ((bb->in_count > 1) && (j == bb->in_count)) {
 582                                         ins->opcode = op_phi_to_move (ins->opcode);
 583                                         if (ins->opcode == OP_VMOVE)
 584                                                 g_assert (ins->klass);
 585                                         ins->sreg1 = first;
 586                                 } else {
 587                                         for (j = 0; j < bb->in_count; j++) {
 588                                                 MonoBasicBlock *pred = bb->in_bb [j];
 589                                                 int sreg = ins->inst_phi_args [j + 1];
 590
 591                                                 if (cfg->verbose_level >= 4)
 592                                                         printf ("\tADD R%d <- R%d in BB%d\n", var->dreg, sreg, pred->block_num);
 593                                                 if (var->dreg != sreg) {
 594                                                         MONO_INST_NEW (cfg, move, op_phi_to_move (ins->opcode));
 595                                                         if (move->opcode == OP_VMOVE) {
 596                                                                 g_assert (ins->klass);
 597                                                                 move->klass = ins->klass;
 598                                                         }
 599                                                         move->dreg = var->dreg;
 600                                                         move->sreg1 = sreg;
 601                                                         mono_add_ins_to_end (pred, move);
 602                                                 }
 603                                         }
 604
 605                                         NULLIFY_INS (ins);
 606                                 }
 607                         }
 608                 }
 609         }
 610
 611         if (cfg->verbose_level >= 4) {
 612                 for (i = 0; i < cfg->num_bblocks; ++i) {
 613                         MonoBasicBlock *bb = cfg->bblocks [i];
 614
 615                         mono_print_bb (bb, "AFTER REMOVE SSA:");
 616                 }
 617         }
 618
 619         /*
 620          * Removal of SSA form introduces many copies. To avoid this, we tyry to coalesce
 621          * the variables if possible. Since the newly introduced SSA variables don't
 622          * have overlapping live ranges (because we don't do agressive optimization), we
 623          * can coalesce them into the original variable.
 624          */
 625
 626         for (bbindex = 0; bbindex < cfg->num_bblocks; ++bbindex) {
 627                 MonoBasicBlock *bb = cfg->bblocks [bbindex];
 628
 629                 for (ins = bb->code; ins; ins = ins->next) {
 630                         const char *spec = INS_INFO (ins->opcode);
 631                         int num_sregs;
 632                         int sregs [MONO_MAX_SRC_REGS];
 633
 634                         if (ins->opcode == OP_NOP)
 635                                 continue;
 636
 637                         if (spec [MONO_INST_DEST] != ' ') {
 638                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 639
 640                                 if (var) {
 641                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 642
 643                                         /*
 644                                          * The third condition avoids coalescing with variables eliminated
 645                                          * during deadce.
 646                                          */
 647                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 648                                                 printf ("COALESCE: R%d -> R%d\n", ins->dreg, cfg->varinfo [vmv->reg]->dreg);
 649                                                 ins->dreg = cfg->varinfo [vmv->reg]->dreg;
 650                                         }
 651                                 }
 652                         }
 653
 654                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 655                         for (i = 0; i < num_sregs; ++i) {
 656                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 657
 658                                 if (var) {
 659                                         MonoMethodVar *vmv = MONO_VARINFO (cfg, var->inst_c0);
 660
 661                                         if ((vmv->reg != -1) && (vmv->idx != vmv->reg) && (MONO_VARINFO (cfg, vmv->reg)->reg != -1)) {
 662                                                 printf ("COALESCE: R%d -> R%d\n", sregs [i], cfg->varinfo [vmv->reg]->dreg);
 663                                                 sregs [i] = cfg->varinfo [vmv->reg]->dreg;
 664                                         }
 665                                 }
 666                         }
 667                         mono_inst_set_src_registers (ins, sregs);
 668                 }
 669         }
 670
 671         for (i = 0; i < cfg->num_varinfo; ++i) {
 672                 MONO_VARINFO (cfg, i)->reg = -1;
 673         }
 674
 675         if (cfg->comp_done & MONO_COMP_REACHABILITY)
 676                 unlink_unused_bblocks (cfg);
 677
 678         cfg->comp_done &= ~MONO_COMP_LIVENESS;
 679
 680         cfg->comp_done &= ~MONO_COMP_SSA;
 681 }
 682
 683 static void
 684 mono_ssa_create_def_use (MonoCompile *cfg)
 685 {
 686         MonoBasicBlock *bb;
 687         MonoInst *ins;
 688         int i;
 689
 690         g_assert (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 691
 692         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 693                 for (ins = bb->code; ins; ins = ins->next) {
 694                         const char *spec = INS_INFO (ins->opcode);
 695                         MonoMethodVar *info;
 696                         int num_sregs;
 697                         int sregs [MONO_MAX_SRC_REGS];
 698
 699                         if (ins->opcode == OP_NOP)
 700                                 continue;
 701
 702                         /* SREGs */
 703                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 704                         for (i = 0; i < num_sregs; ++i) {
 705                                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 706                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 707                                         record_use (cfg, var, bb, ins);
 708                         }
 709
 710                         if (MONO_IS_STORE_MEMBASE (ins)) {
 711                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 712                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 713                                         record_use (cfg, var, bb, ins);
 714                         }
 715
 716                         if (MONO_IS_PHI (ins)) {
 717                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 718                                         g_assert (ins->inst_phi_args [i] != -1);
 719                                         record_use (cfg,  get_vreg_to_inst (cfg, ins->inst_phi_args [i]), bb, ins);
 720                                 }
 721                         }
 722
 723                         /* DREG */
 724                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins)) {
 725                                 MonoInst *var = get_vreg_to_inst (cfg, ins->dreg);
 726
 727                                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 728                                         info = MONO_VARINFO (cfg, var->inst_c0);
 729                                         info->def = ins;
 730                                         info->def_bb = bb;
 731                                 }
 732                         }
 733                 }
 734         }
 735
 736         cfg->comp_done |= MONO_COMP_SSA_DEF_USE;
 737 }
 738
 739 static void
 740 mono_ssa_copyprop (MonoCompile *cfg)
 741 {
 742         int i, index;
 743         GList *l;
 744
 745         g_assert ((cfg->comp_done & MONO_COMP_SSA_DEF_USE));
 746
 747         for (index = 0; index < cfg->num_varinfo; ++index) {
 748                 MonoInst *var = cfg->varinfo [index];
 749                 MonoMethodVar *info = MONO_VARINFO (cfg, index);
 750
 751                 if (info->def && (MONO_IS_MOVE (info->def))) {
 752                         MonoInst *var2 = get_vreg_to_inst (cfg, info->def->sreg1);
 753
 754                         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))) {
 755                                 /* Rewrite all uses of var to be uses of var2 */
 756                                 int dreg = var->dreg;
 757                                 int sreg1 = var2->dreg;
 758
 759                                 l = info->uses;
 760                                 while (l) {
 761                                         MonoVarUsageInfo *u = (MonoVarUsageInfo*)l->data;
 762                                         MonoInst *ins = u->inst;
 763                                         GList *next = l->next;
 764                                         int num_sregs;
 765                                         int sregs [MONO_MAX_SRC_REGS];
 766
 767                                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 768                                         for (i = 0; i < num_sregs; ++i) {
 769                                                 if (sregs [i] == dreg)
 770                                                         break;
 771                                         }
 772                                         if (i < num_sregs) {
 773                                                 g_assert (sregs [i] == dreg);
 774                                                 sregs [i] = sreg1;
 775                                                 mono_inst_set_src_registers (ins, sregs);
 776                                         } else if (MONO_IS_STORE_MEMBASE (ins) && ins->dreg == dreg) {
 777                                                 ins->dreg = sreg1;
 778                                         } else if (MONO_IS_PHI (ins)) {
 779                                                 for (i = ins->inst_phi_args [0]; i > 0; i--) {
 780                                                         int sreg = ins->inst_phi_args [i];
 781                                                         if (sreg == var->dreg)
 782                                                                 break;
 783                                                 }
 784                                                 g_assert (i > 0);
 785                                                 ins->inst_phi_args [i] = sreg1;
 786                                         }
 787                                         else
 788                                                 g_assert_not_reached ();
 789
 790                                         record_use (cfg, var2, u->bb, ins);
 791
 792                                         l = next;
 793                                 }
 794
 795                                 info->uses = NULL;
 796                         }
 797                 }
 798         }
 799
 800         if (cfg->verbose_level >= 4) {
 801                 MonoBasicBlock *bb;
 802
 803                 for (bb = cfg->bb_entry; bb; bb = bb->next_bb)
 804                         mono_print_bb (bb, "AFTER SSA COPYPROP");
 805         }
 806 }
 807
 808 static int
 809 evaluate_ins (MonoCompile *cfg, MonoInst *ins, MonoInst **res, MonoInst **carray)
 810 {
 811         MonoInst *args [MONO_MAX_SRC_REGS];
 812         int rs [MONO_MAX_SRC_REGS];
 813         MonoInst *c0;
 814         gboolean const_args = TRUE;
 815         const char *spec = INS_INFO (ins->opcode);
 816         int num_sregs, i;
 817         int sregs [MONO_MAX_SRC_REGS];
 818
 819         /* Short-circuit this */
 820         if (ins->opcode == OP_ICONST) {
 821                 *res = ins;
 822                 return 1;
 823         }
 824
 825         if (ins->opcode == OP_NOP)
 826                 return 2;
 827
 828         num_sregs = mono_inst_get_src_registers (ins, sregs);
 829         for (i = 0; i < MONO_MAX_SRC_REGS; ++i)
 830                 args [i] = NULL;
 831         for (i = 0; i < num_sregs; ++i) {
 832                 MonoInst *var = get_vreg_to_inst (cfg, sregs [i]);
 833
 834                 rs [i] = 2;
 835                 args [i] = carray [sregs [i]];
 836                 if (args [i])
 837                         rs [i] = 1;
 838                 else if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
 839                         rs [i] = MONO_VARINFO (cfg, var->inst_c0)->cpstate;
 840                 if (rs [i] != 1)
 841                         const_args = FALSE;
 842         }
 843
 844         c0 = NULL;
 845
 846         if (num_sregs > 0 && const_args) {
 847                 g_assert (num_sregs <= 2);
 848                 if ((spec [MONO_INST_DEST] != ' ') && carray [ins->dreg]) {
 849                         // Cached value
 850                         *res = carray [ins->dreg];
 851                         return 1;
 852                 }
 853                 c0 = mono_constant_fold_ins (cfg, ins, args [0], args [1], FALSE);
 854                 if (c0) {
 855                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
 856                                 printf ("\t cfold -> ");
 857                                 mono_print_ins (c0);
 858                         }
 859                         *res = c0;
 860                         return 1;
 861                 }
 862                 else
 863                         /* Can't cfold this ins */
 864                         return 2;
 865         }
 866
 867         if (num_sregs == 0)
 868                 return 2;
 869         for (i = 0; i < num_sregs; ++i) {
 870                 if (rs [i] == 2)
 871                         return 2;
 872         }
 873         return 0;
 874 }
 875
 876 static inline void
 877 change_varstate (MonoCompile *cfg, GList **cvars, MonoMethodVar *info, int state, MonoInst *c0, MonoInst **carray)
 878 {
 879         if (info->cpstate >= state)
 880                 return;
 881
 882         info->cpstate = state;
 883
 884         if (G_UNLIKELY (cfg->verbose_level > 1))
 885                 printf ("\tState of R%d set to %d\n", cfg->varinfo [info->idx]->dreg, info->cpstate);
 886
 887         if (state == 1)
 888                 g_assert (c0);
 889
 890         carray [cfg->varinfo [info->idx]->dreg] = c0;
 891
 892         if (!g_list_find (*cvars, info)) {
 893                 *cvars = g_list_prepend (*cvars, info);
 894         }
 895 }
 896
 897 static inline void
 898 add_cprop_bb (MonoCompile *cfg, MonoBasicBlock *bb, GList **bblist)
 899 {
 900         if (G_UNLIKELY (cfg->verbose_level > 1))
 901                 printf ("\tAdd BB%d to worklist\n", bb->block_num);
 902
 903     if (!(bb->flags &  BB_REACHABLE)) {
 904             bb->flags |= BB_REACHABLE;
 905                 *bblist = g_list_prepend (*bblist, bb);
 906         }
 907 }
 908
 909 static void
 910 visit_inst (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, GList **cvars, GList **bblist, MonoInst **carray)
 911 {
 912         const char *spec = INS_INFO (ins->opcode);
 913
 914         if (ins->opcode == OP_NOP)
 915                 return;
 916
 917         if (cfg->verbose_level > 1)
 918                 mono_print_ins (ins);
 919
 920         /* FIXME: Support longs/floats */
 921         /* FIXME: Work on vregs as well */
 922
 923         if (MONO_IS_PHI (ins)) {
 924                 MonoMethodVar *info = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, ins->dreg)->inst_c0);
 925                 MonoInst *c0 = NULL;
 926                 int j;
 927
 928                 for (j = 1; j <= ins->inst_phi_args [0]; j++) {
 929                         MonoInst *var = get_vreg_to_inst (cfg, ins->inst_phi_args [j]);
 930                         MonoMethodVar *mv = MONO_VARINFO (cfg, var->inst_c0);
 931                         MonoInst *src = mv->def;
 932
 933                         if (mv->def_bb && !(mv->def_bb->flags & BB_REACHABLE))
 934                                 continue;
 935
 936                         if (!mv->def || !src || mv->cpstate == 2) {
 937                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 938                                 break;
 939                         }
 940
 941                         if (mv->cpstate == 0)
 942                                 continue;
 943
 944                         g_assert (carray [var->dreg]);
 945
 946                         if (!c0)
 947                                 c0 = carray [var->dreg];
 948
 949                         /* FIXME: */
 950                         if (c0->opcode != OP_ICONST) {
 951                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 952                                 break;
 953                         }
 954
 955                         if (carray [var->dreg]->inst_c0 != c0->inst_c0) {
 956                                 change_varstate (cfg, cvars, info, 2, NULL, carray);
 957                                 break;
 958                         }
 959                 }
 960
 961                 if (c0 && info->cpstate < 1) {
 962                         change_varstate (cfg, cvars, info, 1, c0, carray);
 963
 964                         g_assert (c0->opcode == OP_ICONST);
 965                 }
 966         }
 967         else if (!MONO_IS_STORE_MEMBASE (ins) && ((spec [MONO_INST_SRC1] != ' ') || (spec [MONO_INST_SRC2] != ' ') || (spec [MONO_INST_DEST] != ' '))) {
 968                 MonoInst *var, *c0;
 969                 int state;
 970
 971                 if (spec [MONO_INST_DEST] !=  ' ')
 972                         var = get_vreg_to_inst (cfg, ins->dreg);
 973                 else
 974                         var = NULL;
 975
 976                 c0 = NULL;
 977                 state = evaluate_ins (cfg, ins, &c0, carray);
 978
 979                 if (var && !(var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT))) {
 980                         MonoMethodVar *info = MONO_VARINFO (cfg, var->inst_c0);
 981
 982                         if (info->cpstate < 2) {
 983                                 if (state == 1)
 984                                         change_varstate (cfg, cvars, info, 1, c0, carray);
 985                                 else if (state == 2)
 986                                         change_varstate (cfg, cvars, info, 2, NULL, carray);
 987                         }
 988                 }
 989                 else if (!var && (ins->dreg != -1)) {
 990                         /*
 991                          * We don't record def-use information for local vregs since it would be
 992                          * expensive. Instead, we depend on the fact that all uses of the vreg are in
 993                          * the same bblock, so they will be examined after the definition.
 994                          * FIXME: This isn't true if the ins is visited through an SSA edge.
 995                          */
 996                         if (c0) {
 997                                 carray [ins->dreg] = c0;
 998                         } else {
 999                                 if (carray [ins->dreg]) {
1000                                         /*
1001                                          * The state of the vreg changed from constant to non-constant
1002                                          * -> need to rescan the whole bblock.
1003                                          */
1004                                         carray [ins->dreg] = NULL;
1005                                         /* FIXME: Speed this up */
1006
1007                                         if (!g_list_find (*bblist, bb))
1008                                                 *bblist = g_list_prepend (*bblist, bb);
1009                                 }
1010                         }
1011                 }
1012
1013                 if (MONO_IS_JUMP_TABLE (ins)) {
1014                         int i;
1015                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1016
1017                         if (!ins->next || ins->next->opcode != OP_PADD) {
1018                                 /* The PADD was optimized away */
1019                                 /* FIXME: handle this as well */
1020                                 for (i = 0; i < table->table_size; i++)
1021                                         if (table->table [i])
1022                                                 add_cprop_bb (cfg, table->table [i], bblist);
1023                                 return;
1024                         }
1025
1026                         g_assert (ins->next->opcode == OP_PADD);
1027                         g_assert (ins->next->sreg1 == ins->dreg);
1028
1029                         if (carray [ins->next->sreg2]) {
1030 #if SIZEOF_REGISTER == 8
1031                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1032 #else
1033                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1034 #endif
1035                                 if ((idx < 0) || (idx >= table->table_size))
1036                                         /* Out-of-range, no branch is executed */
1037                                         return;
1038                                 else
1039                                         if (table->table [idx])
1040                                                 add_cprop_bb (cfg, table->table [idx], bblist);
1041                         }
1042                         else {
1043                                 for (i = 0; i < table->table_size; i++)
1044                                         if (table->table [i])
1045                                                 add_cprop_bb (cfg, table->table [i], bblist);
1046                         }
1047                 }
1048
1049                 if (ins->opcode == OP_SWITCH) {
1050                         int i;
1051                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)ins->inst_p0;
1052
1053                         for (i = 0; i < table->table_size; i++)
1054                                 if (table->table [i])
1055                                         add_cprop_bb (cfg, table->table [i], bblist);
1056                 }
1057
1058                 /* Handle COMPARE+BRCOND pairs */
1059                 if (ins->next && MONO_IS_COND_BRANCH_OP (ins->next)) {
1060                         if (c0) {
1061                                 g_assert (c0->opcode == OP_ICONST);
1062
1063                                 if (c0->inst_c0)
1064                                         ins->next->flags |= MONO_INST_CFOLD_TAKEN;
1065                                 else
1066                                         ins->next->flags |= MONO_INST_CFOLD_NOT_TAKEN;
1067                         }
1068                         else {
1069                                 ins->next->flags &= ~(MONO_INST_CFOLD_TAKEN | MONO_INST_CFOLD_NOT_TAKEN);
1070                         }
1071
1072                         visit_inst (cfg, bb, ins->next, cvars, bblist, carray);
1073                 }
1074         } else if (ins->opcode == OP_BR) {
1075                 add_cprop_bb (cfg, ins->inst_target_bb, bblist);
1076         } else if (MONO_IS_COND_BRANCH_OP (ins)) {
1077                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1078                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1079                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1080                         if (ins->inst_false_bb)
1081                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1082         } else {
1083                         add_cprop_bb (cfg, ins->inst_true_bb, bblist);
1084                         if (ins->inst_false_bb)
1085                                 add_cprop_bb (cfg, ins->inst_false_bb, bblist);
1086                 }
1087         }
1088 }
1089
1090 /**
1091  * fold_ins:
1092  *
1093  *   Replace INS with its constant value, if it exists
1094  */
1095 static void
1096 fold_ins (MonoCompile *cfg, MonoBasicBlock *bb, MonoInst *ins, MonoInst **carray)
1097 {
1098         const char *spec = INS_INFO (ins->opcode);
1099         int opcode2;
1100         int num_sregs = mono_inst_get_num_src_registers (ins);
1101
1102         if ((ins->opcode != OP_NOP) && (ins->dreg != -1) && !MONO_IS_STORE_MEMBASE (ins)) {
1103                 if (carray [ins->dreg] && (spec [MONO_INST_DEST] == 'i') && (ins->dreg >= MONO_MAX_IREGS)) {
1104                         /* Perform constant folding */
1105                         /* FIXME: */
1106                         g_assert (carray [ins->dreg]->opcode == OP_ICONST);
1107                         ins->opcode = OP_ICONST;
1108                         ins->inst_c0 = carray [ins->dreg]->inst_c0;
1109                         MONO_INST_NULLIFY_SREGS (ins);
1110                 } else if (num_sregs == 2 && carray [ins->sreg2]) {
1111                         /* Perform op->op_imm conversion */
1112                         opcode2 = mono_op_to_op_imm (ins->opcode);
1113                         if (opcode2 != -1) {
1114                                 ins->opcode = opcode2;
1115                                 ins->inst_imm = carray [ins->sreg2]->inst_c0;
1116                                 ins->sreg2 = -1;
1117
1118                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
1119                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
1120                         }
1121                 } else {
1122                         /* FIXME: Handle 3 op insns */
1123                 }
1124
1125                 if (MONO_IS_JUMP_TABLE (ins)) {
1126                         int i;
1127                         MonoJumpInfoBBTable *table = (MonoJumpInfoBBTable *)MONO_JUMP_TABLE_FROM_INS (ins);
1128
1129                         if (!ins->next || ins->next->opcode != OP_PADD) {
1130                                 /* The PADD was optimized away */
1131                                 /* FIXME: handle this as well */
1132                                 return;
1133                         }
1134
1135                         g_assert (ins->next->opcode == OP_PADD);
1136                         g_assert (ins->next->sreg1 == ins->dreg);
1137                         g_assert (ins->next->next->opcode == OP_LOAD_MEMBASE);
1138
1139                         if (carray [ins->next->sreg2]) {
1140                                 /* Convert to a simple branch */
1141 #if SIZEOF_REGISTER == 8
1142                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 3;
1143 #else
1144                                 int idx = carray [ins->next->sreg2]->inst_c0 >> 2;
1145 #endif
1146
1147                                 if (!((idx >= 0) && (idx < table->table_size))) {
1148                                         /* Out of range, eliminate the whole switch */
1149                                         for (i = 0; i < table->table_size; ++i) {
1150                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1151                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1152                                         }
1153
1154                                         NULLIFY_INS (ins);
1155                                         NULLIFY_INS (ins->next);
1156                                         NULLIFY_INS (ins->next->next);
1157                                         if (ins->next->next->next)
1158                                                 NULLIFY_INS (ins->next->next->next);
1159
1160                                         return;
1161                                 }
1162
1163                                 if (!ins->next->next->next || ins->next->next->next->opcode != OP_BR_REG) {
1164                                         /* A one-way switch which got optimized away */
1165                                         if (G_UNLIKELY (cfg->verbose_level > 1)) {
1166                                                 printf ("\tNo cfold on ");
1167                                                 mono_print_ins (ins);
1168                                         }
1169                                         return;
1170                                 }
1171
1172                                 if (G_UNLIKELY (cfg->verbose_level > 1)) {
1173                                         printf ("\tcfold on ");
1174                                         mono_print_ins (ins);
1175                                 }
1176
1177                                 /* Unlink target bblocks */
1178                                 for (i = 0; i < table->table_size; ++i) {
1179                                         if (table->table [i] != table->table [idx]) {
1180                                                 remove_bb_from_phis (cfg, bb, table->table [i]);
1181                                                 mono_unlink_bblock (cfg, bb, table->table [i]);
1182                                         }
1183                                 }
1184
1185                                 /* Change the OP_BR_REG to a simple branch */
1186                                 ins->next->next->next->opcode = OP_BR;
1187                                 ins->next->next->next->inst_target_bb = table->table [idx];
1188                                 ins->next->next->next->sreg1 = -1;
1189
1190                                 /* Nullify the other instructions */
1191                                 NULLIFY_INS (ins);
1192                                 NULLIFY_INS (ins->next);
1193                                 NULLIFY_INS (ins->next->next);
1194                         }
1195                 }
1196         }
1197         else if (MONO_IS_COND_BRANCH_OP (ins)) {
1198                 if (ins->flags & MONO_INST_CFOLD_TAKEN) {
1199                         remove_bb_from_phis (cfg, bb, ins->inst_false_bb);
1200                         mono_unlink_bblock (cfg, bb, ins->inst_false_bb);
1201                         ins->opcode = OP_BR;
1202                         ins->inst_target_bb = ins->inst_true_bb;
1203                 } else if (ins->flags & MONO_INST_CFOLD_NOT_TAKEN) {
1204                         remove_bb_from_phis (cfg, bb, ins->inst_true_bb);
1205                         mono_unlink_bblock (cfg, bb, ins->inst_true_bb);
1206                         ins->opcode = OP_BR;
1207                         ins->inst_target_bb = ins->inst_false_bb;
1208                 }
1209         }
1210 }
1211
1212 void
1213 mono_ssa_cprop (MonoCompile *cfg)
1214 {
1215         MonoInst **carray;
1216         MonoBasicBlock *bb;
1217         GList *bblock_list, *cvars;
1218         GList *tmp;
1219         int i;
1220         //printf ("SIMPLE OPTS BB%d %s\n", bb->block_num, mono_method_full_name (cfg->method, TRUE));
1221
1222         carray = g_new0 (MonoInst*, cfg->next_vreg);
1223
1224         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1225                 mono_ssa_create_def_use (cfg);
1226
1227         bblock_list = g_list_prepend (NULL, cfg->bb_entry);
1228         cfg->bb_entry->flags |= BB_REACHABLE;
1229
1230         memset (carray, 0, sizeof (MonoInst *) * cfg->num_varinfo);
1231
1232         for (i = 0; i < cfg->num_varinfo; i++) {
1233                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1234                 if (!info->def)
1235                         info->cpstate = 2;
1236         }
1237
1238         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1239                 /*
1240                  * FIXME: This should be bb->flags & BB_FLAG_EXCEPTION_HANDLER, but
1241                  * that would still allow unreachable try's to be removed.
1242                  */
1243                 if (bb->region)
1244                         add_cprop_bb (cfg, bb, &bblock_list);
1245         }
1246
1247         cvars = NULL;
1248
1249         while (bblock_list) {
1250                 MonoInst *inst;
1251
1252                 bb = (MonoBasicBlock *)bblock_list->data;
1253
1254                 bblock_list = g_list_delete_link (bblock_list, bblock_list);
1255
1256                 g_assert (bb->flags &  BB_REACHABLE);
1257
1258                 /*
1259                  * Some bblocks are linked to 2 others even through they fall through to the
1260                  * next bblock.
1261                  */
1262                 if (!(bb->last_ins && MONO_IS_BRANCH_OP (bb->last_ins))) {
1263                         for (i = 0; i < bb->out_count; ++i)
1264                                 add_cprop_bb (cfg, bb->out_bb [i], &bblock_list);
1265                 }
1266
1267                 if (cfg->verbose_level > 1)
1268                         printf ("\nSSA CONSPROP BB%d:\n", bb->block_num);
1269
1270                 for (inst = bb->code; inst; inst = inst->next) {
1271                         visit_inst (cfg, bb, inst, &cvars, &bblock_list, carray);
1272                 }
1273
1274                 while (cvars) {
1275                         MonoMethodVar *info = (MonoMethodVar *)cvars->data;
1276                         cvars = g_list_delete_link (cvars, cvars);
1277
1278                         for (tmp = info->uses; tmp; tmp = tmp->next) {
1279                                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1280                                 if (!(ui->bb->flags & BB_REACHABLE))
1281                                         continue;
1282                                 visit_inst (cfg, ui->bb, ui->inst, &cvars, &bblock_list, carray);
1283                         }
1284                 }
1285         }
1286
1287         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1288                 MonoInst *inst;
1289                 for (inst = bb->code; inst; inst = inst->next) {
1290                         fold_ins (cfg, bb, inst, carray);
1291                 }
1292         }
1293
1294         g_free (carray);
1295
1296         cfg->comp_done |= MONO_COMP_REACHABILITY;
1297
1298         /* fixme: we should update usage infos during cprop, instead of computing it again */
1299         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1300         for (i = 0; i < cfg->num_varinfo; i++) {
1301                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1302                 info->def = NULL;
1303                 info->uses = NULL;
1304         }
1305 }
1306
1307 static inline void
1308 add_to_dce_worklist (MonoCompile *cfg, MonoMethodVar *var, MonoMethodVar *use, GList **wl)
1309 {
1310         GList *tmp;
1311
1312         *wl = g_list_prepend_mempool (cfg->mempool, *wl, use);
1313
1314         for (tmp = use->uses; tmp; tmp = tmp->next) {
1315                 MonoVarUsageInfo *ui = (MonoVarUsageInfo *)tmp->data;
1316                 if (ui->inst == var->def) {
1317                         /* from the mempool */
1318                         use->uses = g_list_remove_link (use->uses, tmp);
1319                         break;
1320                 }
1321         }
1322 }
1323
1324 void
1325 mono_ssa_deadce (MonoCompile *cfg)
1326 {
1327         int i;
1328         GList *work_list;
1329
1330         g_assert (cfg->comp_done & MONO_COMP_SSA);
1331
1332         //printf ("DEADCE %s\n", mono_method_full_name (cfg->method, TRUE));
1333
1334         if (!(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1335                 mono_ssa_create_def_use (cfg);
1336
1337         mono_ssa_copyprop (cfg);
1338
1339         work_list = NULL;
1340         for (i = 0; i < cfg->num_varinfo; i++) {
1341                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1342                 work_list = g_list_prepend_mempool (cfg->mempool, work_list, info);
1343         }
1344
1345         while (work_list) {
1346                 MonoMethodVar *info = (MonoMethodVar *)work_list->data;
1347                 work_list = g_list_remove_link (work_list, work_list);
1348
1349                 /*
1350                  * The second part of the condition happens often when PHI nodes have their dreg
1351                  * as one of their arguments due to the fact that we use the original vars.
1352                  */
1353                 if (info->def && (!info->uses || ((info->uses->next == NULL) && (((MonoVarUsageInfo*)info->uses->data)->inst == info->def)))) {
1354                         MonoInst *def = info->def;
1355
1356                         /* Eliminating FMOVE could screw up the fp stack */
1357                         if (MONO_IS_MOVE (def) && (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE))) {
1358                                 MonoInst *src_var = get_vreg_to_inst (cfg, def->sreg1);
1359                                 if (src_var && !(src_var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1360                                         add_to_dce_worklist (cfg, info, MONO_VARINFO (cfg, src_var->inst_c0), &work_list);
1361                                 NULLIFY_INS (def);
1362                                 info->reg = -1;
1363                         } else if ((def->opcode == OP_ICONST) || (def->opcode == OP_I8CONST) || MONO_IS_ZERO (def)) {
1364                                 NULLIFY_INS (def);
1365                                 info->reg = -1;
1366                         } else if (MONO_IS_PHI (def)) {
1367                                 int j;
1368                                 for (j = def->inst_phi_args [0]; j > 0; j--) {
1369                                         MonoMethodVar *u = MONO_VARINFO (cfg, get_vreg_to_inst (cfg, def->inst_phi_args [j])->inst_c0);
1370                                         add_to_dce_worklist (cfg, info, u, &work_list);
1371                                 }
1372                                 NULLIFY_INS (def);
1373                                 info->reg = -1;
1374                         }
1375                         else if (def->opcode == OP_NOP) {
1376                         }
1377                         //else
1378                         //mono_print_ins (def);
1379                 }
1380
1381         }
1382 }
1383
1384 #if 0
1385 void
1386 mono_ssa_strength_reduction (MonoCompile *cfg)
1387 {
1388         MonoBasicBlock *bb;
1389         int i;
1390
1391         g_assert (cfg->comp_done & MONO_COMP_SSA);
1392         g_assert (cfg->comp_done & MONO_COMP_LOOPS);
1393         g_assert (cfg->comp_done & MONO_COMP_SSA_DEF_USE);
1394
1395         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1396                 GList *lp = bb->loop_blocks;
1397
1398                 if (lp) {
1399                         MonoBasicBlock *h = (MonoBasicBlock *)lp->data;
1400
1401                         /* we only consider loops with 2 in bblocks */
1402                         if (!h->in_count == 2)
1403                                 continue;
1404
1405                         for (i = 0; i < cfg->num_varinfo; i++) {
1406                                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1407
1408                                 if (info->def && info->def->ssa_op == MONO_SSA_STORE &&
1409                                     info->def->inst_i0->opcode == OP_LOCAL && g_list_find (lp, info->def_bb)) {
1410                                         MonoInst *v = info->def->inst_i1;
1411
1412
1413                                         printf ("FOUND %d in %s\n", info->idx, mono_method_full_name (cfg->method, TRUE));
1414                                 }
1415                         }
1416                 }
1417         }
1418 }
1419 #endif
1420
1421 void
1422 mono_ssa_loop_invariant_code_motion (MonoCompile *cfg)
1423 {
1424         MonoBasicBlock *bb, *h, *idom;
1425         MonoInst *ins, *n, *tins;
1426         int i;
1427
1428         g_assert (cfg->comp_done & MONO_COMP_SSA);
1429         if (!(cfg->comp_done & MONO_COMP_LOOPS) || !(cfg->comp_done & MONO_COMP_SSA_DEF_USE))
1430                 return;
1431
1432         for (bb = cfg->bb_entry->next_bb; bb; bb = bb->next_bb) {
1433                 GList *lp = bb->loop_blocks;
1434
1435                 if (!lp)
1436                         continue;
1437                 h = (MonoBasicBlock *)lp->data;
1438                 if (bb != h)
1439                         continue;
1440                 MONO_BB_FOR_EACH_INS_SAFE (bb, n, ins) {
1441                         /*
1442                          * Try to move instructions out of loop headers into the preceeding bblock.
1443                          */
1444                         if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS || ins->opcode == OP_AOTCONST || ins->opcode == OP_GENERIC_CLASS_INIT) {
1445                                 gboolean skip;
1446                                 int sreg;
1447
1448                                 idom = h->idom;
1449                                 /*
1450                                  * h->nesting is needed to work around:
1451                                  * http://llvm.org/bugs/show_bug.cgi?id=17868
1452                                  */
1453                                 if (!(idom && idom->last_ins && idom->last_ins->opcode == OP_BR && idom->last_ins->inst_target_bb == h && h->nesting == 1)) {
1454                                         continue;
1455                                 }
1456
1457                                 /*
1458                                  * Make sure there are no instructions with side effects before ins.
1459                                  */
1460                                 skip = FALSE;
1461                                 MONO_BB_FOR_EACH_INS (bb, tins) {
1462                                         if (tins == ins)
1463                                                 break;
1464                                         if (!MONO_INS_HAS_NO_SIDE_EFFECT (tins)) {
1465                                                 skip = TRUE;
1466                                                 break;
1467                                         }
1468                                 }
1469                                 if (skip) {
1470                                         /*
1471                                           printf ("%s\n", mono_method_full_name (cfg->method, TRUE));
1472                                           mono_print_ins (tins);
1473                                         */
1474                                         continue;
1475                                 }
1476
1477                                 /* Make sure we don't move the instruction before the def of its sreg */
1478                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN || ins->opcode == OP_CHECK_THIS)
1479                                         sreg = ins->sreg1;
1480                                 else
1481                                         sreg = -1;
1482                                 if (sreg != -1) {
1483                                         MonoInst *tins, *var;
1484
1485                                         skip = FALSE;
1486                                         for (tins = ins->prev; tins; tins = tins->prev) {
1487                                                 const char *spec = INS_INFO (tins->opcode);
1488
1489                                                 if (tins->opcode == OP_MOVE && tins->dreg == sreg) {
1490                                                         sreg = tins->sreg1;
1491                                                 } if (spec [MONO_INST_DEST] != ' ' && tins->dreg == sreg) {
1492                                                         skip = TRUE;
1493                                                         break;
1494                                                 }
1495                                         }
1496                                         if (skip)
1497                                                 continue;
1498                                         var = get_vreg_to_inst (cfg, sreg);
1499                                         if (var && (var->flags & (MONO_INST_VOLATILE|MONO_INST_INDIRECT)))
1500                                                 continue;
1501                                         ins->sreg1 = sreg;
1502                                 }
1503
1504                                 if (cfg->verbose_level > 1) {
1505                                         printf ("licm in BB%d on ", bb->block_num);
1506                                         mono_print_ins (ins);
1507                                 }
1508                                 //{ static int count = 0; count ++; printf ("%d\n", count); }
1509                                 MONO_REMOVE_INS (bb, ins);
1510                                 mono_bblock_insert_before_ins (idom, idom->last_ins, ins);
1511                                 if (ins->opcode == OP_LDLEN || ins->opcode == OP_STRLEN)
1512                                         idom->has_array_access = TRUE;
1513                         }
1514                 }
1515         }
1516
1517         cfg->comp_done &=  ~MONO_COMP_SSA_DEF_USE;
1518         for (i = 0; i < cfg->num_varinfo; i++) {
1519                 MonoMethodVar *info = MONO_VARINFO (cfg, i);
1520                 info->def = NULL;
1521                 info->uses = NULL;
1522         }
1523 }
1524
1525 #else /* !DISABLE_JIT */
1526
1527 MONO_EMPTY_SOURCE_FILE (ssa);
1528
1529 #endif /* !DISABLE_JIT */