mono/mini/local-propagation.c

   1 /*
   2  * local-propagation.c: Local constant, copy and tree propagation.
   3  *
   4  * To make some sense of the tree mover, read mono/docs/tree-mover.txt
   5  *
   6  * Author:
   7  *   Paolo Molaro (lupus@ximian.com)
   8  *   Dietmar Maurer (dietmar@ximian.com)
   9  *   Massimiliano Mantione (massi@ximian.com)
  10  *
  11  * (C) 2006 Novell, Inc.  http://www.novell.com
  12  * Copyright 2011 Xamarin, Inc (http://www.xamarin.com)
  13  */
  14
  15 #include <config.h>
  16 #ifndef DISABLE_JIT
  17
  18 #include <string.h>
  19 #include <stdio.h>
  20 #ifdef HAVE_ALLOCA_H
  21 #include <alloca.h>
  22 #endif
  23
  24 #include <mono/metadata/debug-helpers.h>
  25 #include <mono/metadata/mempool.h>
  26 #include <mono/metadata/opcodes.h>
  27 #include "mini.h"
  28 #include "ir-emit.h"
  29
  30 #ifndef MONO_ARCH_IS_OP_MEMBASE
  31 #define MONO_ARCH_IS_OP_MEMBASE(opcode) FALSE
  32 #endif
  33
  34 static inline MonoBitSet*
  35 mono_bitset_mp_new_noinit (MonoMemPool *mp,  guint32 max_size)
  36 {
  37         int size = mono_bitset_alloc_size (max_size, 0);
  38         gpointer mem;
  39
  40         mem = mono_mempool_alloc (mp, size);
  41         return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
  42 }
  43
  44 /*
  45  * Replaces ins with optimized opcodes.
  46  *
  47  * We can emit to cbb the equivalent instructions which will be used as
  48  * replacement for ins, or simply change the fields of ins. Spec needs to
  49  * be updated if we silently change the opcode of ins.
  50  *
  51  * Returns TRUE if additional vregs were allocated.
  52  */
  53 static gboolean
  54 mono_strength_reduction_ins (MonoCompile *cfg, MonoInst *ins, const char **spec)
  55 {
  56         gboolean allocated_vregs = FALSE;
  57
  58         /* FIXME: Add long/float */
  59         switch (ins->opcode) {
  60         case OP_MOVE:
  61         case OP_XMOVE:
  62                 if (ins->dreg == ins->sreg1) {
  63                         NULLIFY_INS (ins);
  64                 }
  65                 break;
  66         case OP_ADD_IMM:
  67         case OP_IADD_IMM:
  68         case OP_SUB_IMM:
  69         case OP_ISUB_IMM:
  70 #if SIZEOF_REGISTER == 8
  71         case OP_LADD_IMM:
  72         case OP_LSUB_IMM:
  73 #endif
  74                 if (ins->inst_imm == 0) {
  75                         ins->opcode = OP_MOVE;
  76                 }
  77                 break;
  78         case OP_MUL_IMM:
  79         case OP_IMUL_IMM:
  80 #if SIZEOF_REGISTER == 8
  81         case OP_LMUL_IMM:
  82 #endif
  83                 if (ins->inst_imm == 0) {
  84                         ins->opcode = (ins->opcode == OP_LMUL_IMM) ? OP_I8CONST : OP_ICONST;
  85                         ins->inst_c0 = 0;
  86                         ins->sreg1 = -1;
  87                 } else if (ins->inst_imm == 1) {
  88                         ins->opcode = OP_MOVE;
  89                 } else if ((ins->opcode == OP_IMUL_IMM) && (ins->inst_imm == -1)) {
  90                         ins->opcode = OP_INEG;
  91                 } else if ((ins->opcode == OP_LMUL_IMM) && (ins->inst_imm == -1)) {
  92                         ins->opcode = OP_LNEG;
  93                 } else {
  94                         int power2 = mono_is_power_of_two (ins->inst_imm);
  95                         if (power2 >= 0) {
  96                                 ins->opcode = (ins->opcode == OP_MUL_IMM) ? OP_SHL_IMM : ((ins->opcode == OP_LMUL_IMM) ? OP_LSHL_IMM : OP_ISHL_IMM);
  97                                 ins->inst_imm = power2;
  98                         }
  99                 }
 100                 break;
 101         case OP_IREM_UN_IMM:
 102         case OP_IDIV_UN_IMM: {
 103                 int c = ins->inst_imm;
 104                 int power2 = mono_is_power_of_two (c);
 105
 106                 if (power2 >= 0) {
 107                         if (ins->opcode == OP_IREM_UN_IMM) {
 108                                 ins->opcode = OP_IAND_IMM;
 109                                 ins->sreg2 = -1;
 110                                 ins->inst_imm = (1 << power2) - 1;
 111                         } else if (ins->opcode == OP_IDIV_UN_IMM) {
 112                                 ins->opcode = OP_ISHR_UN_IMM;
 113                                 ins->sreg2 = -1;
 114                                 ins->inst_imm = power2;
 115                         }
 116                 }
 117                 break;
 118         }
 119         case OP_IDIV_IMM: {
 120                 int c = ins->inst_imm;
 121                 int power2 = mono_is_power_of_two (c);
 122
 123                 if (power2 == 1) {
 124                         int r1 = mono_alloc_ireg (cfg);
 125
 126                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_UN_IMM, r1, ins->sreg1, 31);
 127                         MONO_EMIT_NEW_BIALU (cfg, OP_IADD, r1, r1, ins->sreg1);
 128                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_IMM, ins->dreg, r1, 1);
 129
 130                         allocated_vregs = TRUE;
 131                 } else if (power2 > 0 && power2 < 31) {
 132                         int r1 = mono_alloc_ireg (cfg);
 133
 134                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_IMM, r1, ins->sreg1, 31);
 135                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_UN_IMM, r1, r1, (32 - power2));
 136                         MONO_EMIT_NEW_BIALU (cfg, OP_IADD, r1, r1, ins->sreg1);
 137                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_IMM, ins->dreg, r1, power2);
 138
 139                         allocated_vregs = TRUE;
 140                 }
 141                 break;
 142         }
 143 #if SIZEOF_REGISTER == 8
 144         case OP_LREM_IMM:
 145 #endif
 146         case OP_IREM_IMM: {
 147                 int power = mono_is_power_of_two (ins->inst_imm);
 148                 if (ins->inst_imm == 1) {
 149                         ins->opcode = OP_ICONST;
 150                         MONO_INST_NULLIFY_SREGS (ins);
 151                         ins->inst_c0 = 0;
 152 #if __s390__
 153                 }
 154 #else
 155                 } else if ((ins->inst_imm > 0) && (ins->inst_imm < (1LL << 32)) && (power != -1)) {
 156                         gboolean is_long = ins->opcode == OP_LREM_IMM;
 157                         int compensator_reg = alloc_ireg (cfg);
 158                         int intermediate_reg;
 159
 160                         /* Based on gcc code */
 161
 162                         /* Add compensation for negative numerators */
 163
 164                         if (power > 1) {
 165                                 intermediate_reg = compensator_reg;
 166                                 MONO_EMIT_NEW_BIALU_IMM (cfg, is_long ? OP_LSHR_IMM : OP_ISHR_IMM, intermediate_reg, ins->sreg1, is_long ? 63 : 31);
 167                         } else {
 168                                 intermediate_reg = ins->sreg1;
 169                         }
 170
 171                         MONO_EMIT_NEW_BIALU_IMM (cfg, is_long ? OP_LSHR_UN_IMM : OP_ISHR_UN_IMM, compensator_reg, intermediate_reg, (is_long ? 64 : 32) - power);
 172                         MONO_EMIT_NEW_BIALU (cfg, is_long ? OP_LADD : OP_IADD, ins->dreg, ins->sreg1, compensator_reg);
 173                         /* Compute remainder */
 174                         MONO_EMIT_NEW_BIALU_IMM (cfg, is_long ? OP_LAND_IMM : OP_AND_IMM, ins->dreg, ins->dreg, (1 << power) - 1);
 175                         /* Remove compensation */
 176                         MONO_EMIT_NEW_BIALU (cfg, is_long ? OP_LSUB : OP_ISUB, ins->dreg, ins->dreg, compensator_reg);
 177
 178                         allocated_vregs = TRUE;
 179                 }
 180 #endif
 181                 break;
 182         }
 183
 184         default:
 185                 break;
 186         }
 187
 188         *spec = INS_INFO (ins->opcode);
 189         return allocated_vregs;
 190 }
 191
 192 /*
 193  * mono_local_cprop:
 194  *
 195  *  A combined local copy and constant propagation pass.
 196  */
 197 void
 198 mono_local_cprop (MonoCompile *cfg)
 199 {
 200         MonoBasicBlock *bb, *bb_opt;
 201         MonoInst **defs;
 202         gint32 *def_index;
 203         int max;
 204         int filter = FILTER_IL_SEQ_POINT;
 205         int initial_max_vregs = cfg->next_vreg;
 206
 207         max = cfg->next_vreg;
 208         defs = (MonoInst **)mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * cfg->next_vreg);
 209         def_index = (gint32 *)mono_mempool_alloc (cfg->mempool, sizeof (guint32) * cfg->next_vreg);
 210         cfg->cbb = bb_opt = mono_mempool_alloc0 ((cfg)->mempool, sizeof (MonoBasicBlock));
 211
 212         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 213                 MonoInst *ins;
 214                 int ins_index;
 215                 int last_call_index;
 216
 217                 /* Manually init the defs entries used by the bblock */
 218                 MONO_BB_FOR_EACH_INS (bb, ins) {
 219                         int sregs [MONO_MAX_SRC_REGS];
 220                         int num_sregs, i;
 221
 222                         if ((ins->dreg != -1) && (ins->dreg < max)) {
 223                                 defs [ins->dreg] = NULL;
 224 #if SIZEOF_REGISTER == 4
 225                                 defs [ins->dreg + 1] = NULL;
 226 #endif
 227                         }
 228
 229                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 230                         for (i = 0; i < num_sregs; ++i) {
 231                                 int sreg = sregs [i];
 232                                 if (sreg < max) {
 233                                         defs [sreg] = NULL;
 234 #if SIZEOF_REGISTER == 4
 235                                         defs [sreg + 1] = NULL;
 236 #endif
 237                                 }
 238                         }
 239                 }
 240
 241                 ins_index = 0;
 242                 last_call_index = -1;
 243                 MONO_BB_FOR_EACH_INS (bb, ins) {
 244                         const char *spec = INS_INFO (ins->opcode);
 245                         int regtype, srcindex, sreg;
 246                         int num_sregs;
 247                         int sregs [MONO_MAX_SRC_REGS];
 248
 249                         if (ins->opcode == OP_NOP) {
 250                                 MONO_DELETE_INS (bb, ins);
 251                                 continue;
 252                         }
 253
 254                         g_assert (ins->opcode > MONO_CEE_LAST);
 255
 256                         /* FIXME: Optimize this */
 257                         if (ins->opcode == OP_LDADDR) {
 258                                 MonoInst *var = (MonoInst *)ins->inst_p0;
 259
 260                                 defs [var->dreg] = NULL;
 261                                 /*
 262                                 if (!MONO_TYPE_ISSTRUCT (var->inst_vtype))
 263                                         break;
 264                                 */
 265                         }
 266
 267                         if (MONO_IS_STORE_MEMBASE (ins)) {
 268                                 sreg = ins->dreg;
 269                                 regtype = 'i';
 270
 271                                 if ((regtype == 'i') && (sreg != -1) && defs [sreg]) {
 272                                         MonoInst *def = defs [sreg];
 273
 274                                         if ((def->opcode == OP_MOVE) && (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) && !vreg_is_volatile (cfg, def->sreg1)) {
 275                                                 int vreg = def->sreg1;
 276                                                 if (cfg->verbose_level > 2) printf ("CCOPY: R%d -> R%d\n", sreg, vreg);
 277                                                 ins->dreg = vreg;
 278                                         }
 279                                 }
 280                         }
 281
 282                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 283                         for (srcindex = 0; srcindex < num_sregs; ++srcindex) {
 284                                 MonoInst *def;
 285
 286                                 mono_inst_get_src_registers (ins, sregs);
 287
 288                                 regtype = spec [MONO_INST_SRC1 + srcindex];
 289                                 sreg = sregs [srcindex];
 290
 291                                 if ((regtype == ' ') || (sreg == -1) || (!defs [sreg]))
 292                                         continue;
 293
 294                                 def = defs [sreg];
 295
 296                                 /* Copy propagation */
 297                                 /*
 298                                  * The first check makes sure the source of the copy did not change since
 299                                  * the copy was made.
 300                                  * The second check avoids volatile variables.
 301                                  * The third check avoids copy propagating local vregs through a call,
 302                                  * since the lvreg will be spilled
 303                                  * The fourth check avoids copy propagating a vreg in cases where
 304                                  * it would be eliminated anyway by reverse copy propagation later,
 305                                  * because propagating it would create another use for it, thus making
 306                                  * it impossible to use reverse copy propagation.
 307                                  */
 308                                 /* Enabling this for floats trips up the fp stack */
 309                                 /*
 310                                  * Enabling this for floats on amd64 seems to cause a failure in
 311                                  * basic-math.cs, most likely because it gets rid of some r8->r4
 312                                  * conversions.
 313                                  */
 314                                 if (MONO_IS_MOVE (def) &&
 315                                         (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) &&
 316                                         !vreg_is_volatile (cfg, def->sreg1) &&
 317                                         /* This avoids propagating local vregs across calls */
 318                                         ((get_vreg_to_inst (cfg, def->sreg1) || !defs [def->sreg1] || (def_index [def->sreg1] >= last_call_index) || (def->opcode == OP_VMOVE))) &&
 319                                         !(defs [def->sreg1] && mono_inst_next (defs [def->sreg1], filter) == def) &&
 320                                         (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE)) &&
 321                                         (def->opcode != OP_FMOVE)) {
 322                                         int vreg = def->sreg1;
 323
 324                                         if (cfg->verbose_level > 2) printf ("CCOPY/2: R%d -> R%d\n", sreg, vreg);
 325                                         sregs [srcindex] = vreg;
 326                                         mono_inst_set_src_registers (ins, sregs);
 327
 328                                         /* Allow further iterations */
 329                                         srcindex = -1;
 330                                         continue;
 331                                 }
 332
 333                                 /* Constant propagation */
 334                                 /* FIXME: Make is_inst_imm a macro */
 335                                 /* FIXME: Make is_inst_imm take an opcode argument */
 336                                 /* is_inst_imm is only needed for binops */
 337                                 if ((((def->opcode == OP_ICONST) || ((sizeof (gpointer) == 8) && (def->opcode == OP_I8CONST))) &&
 338                                          (((srcindex == 0) && (ins->sreg2 == -1)) || mono_arch_is_inst_imm (def->inst_c0))) ||
 339                                         (!MONO_ARCH_USE_FPSTACK && (def->opcode == OP_R8CONST))) {
 340                                         guint32 opcode2;
 341
 342                                         /* srcindex == 1 -> binop, ins->sreg2 == -1 -> unop */
 343                                         if ((srcindex == 1) && (ins->sreg1 != -1) && defs [ins->sreg1] && (defs [ins->sreg1]->opcode == OP_ICONST) && defs [ins->sreg2]) {
 344                                                 /* Both arguments are constants, perform cfold */
 345                                                 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
 346                                         } else if ((srcindex == 0) && (ins->sreg2 != -1) && defs [ins->sreg2]) {
 347                                                 /* Arg 1 is constant, swap arguments if possible */
 348                                                 int opcode = ins->opcode;
 349                                                 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
 350                                                 if (ins->opcode != opcode) {
 351                                                         /* Allow further iterations */
 352                                                         srcindex = -1;
 353                                                         continue;
 354                                                 }
 355                                         } else if ((srcindex == 0) && (ins->sreg2 == -1)) {
 356                                                 /* Constant unop, perform cfold */
 357                                                 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], NULL, TRUE);
 358                                         }
 359
 360                                         opcode2 = mono_op_to_op_imm (ins->opcode);
 361                                         if ((opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0) && ((srcindex == 1) || (ins->sreg2 == -1))) {
 362                                                 ins->opcode = opcode2;
 363                                                 if ((def->opcode == OP_I8CONST) && (sizeof (gpointer) == 4)) {
 364                                                         ins->inst_ls_word = def->inst_ls_word;
 365                                                         ins->inst_ms_word = def->inst_ms_word;
 366                                                 } else {
 367                                                         ins->inst_imm = def->inst_c0;
 368                                                 }
 369                                                 sregs [srcindex] = -1;
 370                                                 mono_inst_set_src_registers (ins, sregs);
 371
 372                                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
 373                                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
 374
 375                                                 /* Allow further iterations */
 376                                                 srcindex = -1;
 377                                                 continue;
 378                                         }
 379                                         else {
 380                                                 /* Special cases */
 381 #if defined(TARGET_X86) || defined(TARGET_AMD64)
 382                                                 if ((ins->opcode == OP_X86_LEA) && (srcindex == 1)) {
 383 #if SIZEOF_REGISTER == 8
 384                                                         /* FIXME: Use OP_PADD_IMM when the new JIT is done */
 385                                                         ins->opcode = OP_LADD_IMM;
 386 #else
 387                                                         ins->opcode = OP_ADD_IMM;
 388 #endif
 389                                                         ins->inst_imm += def->inst_c0 << ins->backend.shift_amount;
 390                                                         ins->sreg2 = -1;
 391                                                 }
 392 #endif
 393                                                 opcode2 = mono_load_membase_to_load_mem (ins->opcode);
 394                                                 if ((srcindex == 0) && (opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0)) {
 395                                                         ins->opcode = opcode2;
 396                                                         ins->inst_imm = def->inst_c0 + ins->inst_offset;
 397                                                         ins->sreg1 = -1;
 398                                                 }
 399                                         }
 400                                 }
 401                                 else if (((def->opcode == OP_ADD_IMM) || (def->opcode == OP_LADD_IMM)) && (MONO_IS_LOAD_MEMBASE (ins) || MONO_ARCH_IS_OP_MEMBASE (ins->opcode))) {
 402                                         /* ADD_IMM is created by spill_global_vars */
 403                                         /*
 404                                          * We have to guarantee that def->sreg1 haven't changed since def->dreg
 405                                          * was defined. cfg->frame_reg is assumed to remain constant.
 406                                          */
 407                                         if ((def->sreg1 == cfg->frame_reg) || ((mono_inst_next (def, filter) == ins) && (def->dreg != def->sreg1))) {
 408                                                 ins->inst_basereg = def->sreg1;
 409                                                 ins->inst_offset += def->inst_imm;
 410                                         }
 411                                 } else if ((ins->opcode == OP_ISUB_IMM) && (def->opcode == OP_IADD_IMM) && (mono_inst_next (def, filter) == ins) && (def->dreg != def->sreg1)) {
 412                                         ins->sreg1 = def->sreg1;
 413                                         ins->inst_imm -= def->inst_imm;
 414                                 } else if ((ins->opcode == OP_IADD_IMM) && (def->opcode == OP_ISUB_IMM) && (mono_inst_next (def, filter) == ins) && (def->dreg != def->sreg1)) {
 415                                         ins->sreg1 = def->sreg1;
 416                                         ins->inst_imm -= def->inst_imm;
 417                                 } else if (ins->opcode == OP_STOREI1_MEMBASE_REG &&
 418                                                    (def->opcode == OP_ICONV_TO_U1 || def->opcode == OP_ICONV_TO_I1 || def->opcode == OP_SEXT_I4 || (SIZEOF_REGISTER == 8 && def->opcode == OP_LCONV_TO_U1)) &&
 419                                                    (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
 420                                         /* Avoid needless sign extension */
 421                                         ins->sreg1 = def->sreg1;
 422                                 } else if (ins->opcode == OP_STOREI2_MEMBASE_REG &&
 423                                                    (def->opcode == OP_ICONV_TO_U2 || def->opcode == OP_ICONV_TO_I2 || def->opcode == OP_SEXT_I4 || (SIZEOF_REGISTER == 8 && def->opcode == OP_LCONV_TO_I2)) &&
 424                                                    (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
 425                                         /* Avoid needless sign extension */
 426                                         ins->sreg1 = def->sreg1;
 427                                 }
 428                         }
 429
 430                         g_assert (cfg->cbb == bb_opt);
 431                         g_assert (!bb_opt->code);
 432                         /* Do strength reduction here */
 433                         if (mono_strength_reduction_ins (cfg, ins, &spec) && max < cfg->next_vreg) {
 434                                 MonoInst **defs_prev = defs;
 435                                 gint32 *def_index_prev = def_index;
 436                                 guint32 prev_max = max;
 437                                 guint32 additional_vregs = cfg->next_vreg - initial_max_vregs;
 438
 439                                 /* We have more vregs so we need to reallocate defs and def_index arrays */
 440                                 max  = initial_max_vregs + additional_vregs * 2;
 441                                 defs = (MonoInst **)mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * max);
 442                                 def_index = (gint32 *)mono_mempool_alloc (cfg->mempool, sizeof (guint32) * max);
 443
 444                                 /* Keep the entries for the previous vregs, zero the rest */
 445                                 memcpy (defs, defs_prev, sizeof (MonoInst*) * prev_max);
 446                                 memset (defs + prev_max, 0, sizeof (MonoInst*) * (max - prev_max));
 447                                 memcpy (def_index, def_index_prev, sizeof (guint32) * prev_max);
 448                                 memset (def_index + prev_max, 0, sizeof (guint32) * (max - prev_max));
 449                         }
 450
 451                         if (cfg->cbb->code || (cfg->cbb != bb_opt)) {
 452                                 MonoInst *saved_prev = ins->prev;
 453
 454                                 /* If we have code in cbb, we need to replace ins with the decomposition */
 455                                 mono_replace_ins (cfg, bb, ins, &ins->prev, bb_opt, cfg->cbb);
 456                                 bb_opt->code = bb_opt->last_ins = NULL;
 457                                 bb_opt->in_count = bb_opt->out_count = 0;
 458                                 cfg->cbb = bb_opt;
 459
 460                                 /* ins is hanging, continue scanning the emitted code */
 461                                 ins = saved_prev;
 462                                 continue;
 463                         }
 464
 465                         if (spec [MONO_INST_DEST] != ' ') {
 466                                 MonoInst *def = defs [ins->dreg];
 467
 468                                 if (def && (def->opcode == OP_ADD_IMM) && (def->sreg1 == cfg->frame_reg) && (MONO_IS_STORE_MEMBASE (ins))) {
 469                                         /* ADD_IMM is created by spill_global_vars */
 470                                         /* cfg->frame_reg is assumed to remain constant */
 471                                         ins->inst_destbasereg = def->sreg1;
 472                                         ins->inst_offset += def->inst_imm;
 473                                 }
 474                         }
 475
 476                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins) && !vreg_is_volatile (cfg, ins->dreg)) {
 477                                 defs [ins->dreg] = ins;
 478                                 def_index [ins->dreg] = ins_index;
 479                         }
 480
 481                         if (MONO_IS_CALL (ins))
 482                                 last_call_index = ins_index;
 483
 484                         ins_index ++;
 485                 }
 486         }
 487 }
 488
 489 static inline gboolean
 490 reg_is_softreg_no_fpstack (int reg, const char spec)
 491 {
 492         return (spec == 'i' && reg >= MONO_MAX_IREGS)
 493                 || ((spec == 'f' && reg >= MONO_MAX_FREGS) && !MONO_ARCH_USE_FPSTACK)
 494 #ifdef MONO_ARCH_SIMD_INTRINSICS
 495                 || (spec == 'x' && reg >= MONO_MAX_XREGS)
 496 #endif
 497                 || (spec == 'v');
 498 }
 499
 500 static inline gboolean
 501 reg_is_softreg (int reg, const char spec)
 502 {
 503         return (spec == 'i' && reg >= MONO_MAX_IREGS)
 504                 || (spec == 'f' && reg >= MONO_MAX_FREGS)
 505 #ifdef MONO_ARCH_SIMD_INTRINSICS
 506                 || (spec == 'x' && reg >= MONO_MAX_XREGS)
 507 #endif
 508                 || (spec == 'v');
 509 }
 510
 511 static inline gboolean
 512 mono_is_simd_accessor (MonoInst *ins)
 513 {
 514         switch (ins->opcode) {
 515 #ifdef MONO_ARCH_SIMD_INTRINSICS
 516         case OP_INSERT_I1:
 517         case OP_INSERT_I2:
 518         case OP_INSERT_I4:
 519         case OP_INSERT_I8:
 520         case OP_INSERT_R4:
 521         case OP_INSERT_R8:
 522
 523         case OP_INSERTX_U1_SLOW:
 524         case OP_INSERTX_I4_SLOW:
 525         case OP_INSERTX_R4_SLOW:
 526         case OP_INSERTX_R8_SLOW:
 527         case OP_INSERTX_I8_SLOW:
 528                 return TRUE;
 529 #endif
 530         default:
 531                 return FALSE;
 532         }
 533 }
 534
 535 /**
 536  * mono_local_deadce:
 537  *
 538  *   Get rid of the dead assignments to local vregs like the ones created by the
 539  * copyprop pass.
 540  */
 541 void
 542 mono_local_deadce (MonoCompile *cfg)
 543 {
 544         MonoBasicBlock *bb;
 545         MonoInst *ins, *prev;
 546         MonoBitSet *used, *defined;
 547
 548         //mono_print_code (cfg, "BEFORE LOCAL-DEADCE");
 549
 550         /*
 551          * Assignments to global vregs can't be eliminated so this pass must come
 552          * after the handle_global_vregs () pass.
 553          */
 554
 555         used = mono_bitset_mp_new_noinit (cfg->mempool, cfg->next_vreg + 1);
 556         defined = mono_bitset_mp_new_noinit (cfg->mempool, cfg->next_vreg + 1);
 557
 558         /* First pass: collect liveness info */
 559         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 560                 /* Manually init the defs entries used by the bblock */
 561                 MONO_BB_FOR_EACH_INS (bb, ins) {
 562                         const char *spec = INS_INFO (ins->opcode);
 563                         int sregs [MONO_MAX_SRC_REGS];
 564                         int num_sregs, i;
 565
 566                         if (spec [MONO_INST_DEST] != ' ') {
 567                                 mono_bitset_clear_fast (used, ins->dreg);
 568                                 mono_bitset_clear_fast (defined, ins->dreg);
 569 #if SIZEOF_REGISTER == 4
 570                                 /* Regpairs */
 571                                 mono_bitset_clear_fast (used, ins->dreg + 1);
 572                                 mono_bitset_clear_fast (defined, ins->dreg + 1);
 573 #endif
 574                         }
 575                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 576                         for (i = 0; i < num_sregs; ++i) {
 577                                 mono_bitset_clear_fast (used, sregs [i]);
 578 #if SIZEOF_REGISTER == 4
 579                                 mono_bitset_clear_fast (used, sregs [i] + 1);
 580 #endif
 581                         }
 582                 }
 583
 584                 /*
 585                  * Make a reverse pass over the instruction list
 586                  */
 587                 MONO_BB_FOR_EACH_INS_REVERSE_SAFE (bb, prev, ins) {
 588                         const char *spec = INS_INFO (ins->opcode);
 589                         int sregs [MONO_MAX_SRC_REGS];
 590                         int num_sregs, i;
 591                         MonoInst *prev_f = mono_inst_prev (ins, FILTER_NOP | FILTER_IL_SEQ_POINT);
 592
 593                         if (ins->opcode == OP_NOP) {
 594                                 MONO_DELETE_INS (bb, ins);
 595                                 continue;
 596                         }
 597
 598                         g_assert (ins->opcode > MONO_CEE_LAST);
 599
 600                         if (MONO_IS_NON_FP_MOVE (ins) && prev_f) {
 601                                 MonoInst *def;
 602                                 const char *spec2;
 603
 604                                 def = prev_f;
 605                                 spec2 = INS_INFO (def->opcode);
 606
 607                                 /*
 608                                  * Perform a limited kind of reverse copy propagation, i.e.
 609                                  * transform B <- FOO; A <- B into A <- FOO
 610                                  * This isn't copyprop, not deadce, but it can only be performed
 611                                  * after handle_global_vregs () has run.
 612                                  */
 613                                 if (!get_vreg_to_inst (cfg, ins->sreg1) && (spec2 [MONO_INST_DEST] != ' ') && (def->dreg == ins->sreg1) && !mono_bitset_test_fast (used, ins->sreg1) && !MONO_IS_STORE_MEMBASE (def) && reg_is_softreg (ins->sreg1, spec [MONO_INST_DEST]) && !mono_is_simd_accessor (def)) {
 614                                         if (cfg->verbose_level > 2) {
 615                                                 printf ("\tReverse copyprop in BB%d on ", bb->block_num);
 616                                                 mono_print_ins (ins);
 617                                         }
 618
 619                                         def->dreg = ins->dreg;
 620                                         MONO_DELETE_INS (bb, ins);
 621                                         spec = INS_INFO (ins->opcode);
 622                                 }
 623                         }
 624
 625                         /* Enabling this on x86 could screw up the fp stack */
 626                         if (reg_is_softreg_no_fpstack (ins->dreg, spec [MONO_INST_DEST])) {
 627                                 /*
 628                                  * Assignments to global vregs can only be eliminated if there is another
 629                                  * assignment to the same vreg later in the same bblock.
 630                                  */
 631                                 if (!mono_bitset_test_fast (used, ins->dreg) &&
 632                                         (!get_vreg_to_inst (cfg, ins->dreg) || (!bb->extended && !vreg_is_volatile (cfg, ins->dreg) && mono_bitset_test_fast (defined, ins->dreg))) &&
 633                                         MONO_INS_HAS_NO_SIDE_EFFECT (ins)) {
 634                                         /* Happens with CMOV instructions */
 635                                         if (prev_f && prev_f->opcode == OP_ICOMPARE_IMM) {
 636                                                 MonoInst *prev = prev_f;
 637                                                 /*
 638                                                  * Can't use DELETE_INS since that would interfere with the
 639                                                  * FOR_EACH_INS loop.
 640                                                  */
 641                                                 NULLIFY_INS (prev);
 642                                         }
 643                                         //printf ("DEADCE: "); mono_print_ins (ins);
 644                                         MONO_DELETE_INS (bb, ins);
 645                                         spec = INS_INFO (ins->opcode);
 646                                 }
 647
 648                                 if (spec [MONO_INST_DEST] != ' ')
 649                                         mono_bitset_clear_fast (used, ins->dreg);
 650                         }
 651
 652                         if (spec [MONO_INST_DEST] != ' ')
 653                                 mono_bitset_set_fast (defined, ins->dreg);
 654                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 655                         for (i = 0; i < num_sregs; ++i)
 656                                 mono_bitset_set_fast (used, sregs [i]);
 657                         if (MONO_IS_STORE_MEMBASE (ins))
 658                                 mono_bitset_set_fast (used, ins->dreg);
 659
 660                         if (MONO_IS_CALL (ins)) {
 661                                 MonoCallInst *call = (MonoCallInst*)ins;
 662                                 GSList *l;
 663
 664                                 if (call->out_ireg_args) {
 665                                         for (l = call->out_ireg_args; l; l = l->next) {
 666                                                 guint32 regpair, reg;
 667
 668                                                 regpair = (guint32)(gssize)(l->data);
 669                                                 reg = regpair & 0xffffff;
 670
 671                                                 mono_bitset_set_fast (used, reg);
 672                                         }
 673                                 }
 674
 675                                 if (call->out_freg_args) {
 676                                         for (l = call->out_freg_args; l; l = l->next) {
 677                                                 guint32 regpair, reg;
 678
 679                                                 regpair = (guint32)(gssize)(l->data);
 680                                                 reg = regpair & 0xffffff;
 681
 682                                                 mono_bitset_set_fast (used, reg);
 683                                         }
 684                                 }
 685                         }
 686                 }
 687         }
 688
 689         //mono_print_code (cfg, "AFTER LOCAL-DEADCE");
 690 }
 691
 692 #endif /* DISABLE_JIT */