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