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  * Licensed under the MIT license. See LICENSE file in the project root for full license information.
  14  */
  15
  16 #include <config.h>
  17 #ifndef DISABLE_JIT
  18
  19 #include <string.h>
  20 #include <stdio.h>
  21 #ifdef HAVE_ALLOCA_H
  22 #include <alloca.h>
  23 #endif
  24
  25 #include <mono/metadata/debug-helpers.h>
  26 #include <mono/metadata/mempool.h>
  27 #include <mono/metadata/opcodes.h>
  28 #include "mini.h"
  29 #include "ir-emit.h"
  30
  31 #ifndef MONO_ARCH_IS_OP_MEMBASE
  32 #define MONO_ARCH_IS_OP_MEMBASE(opcode) FALSE
  33 #endif
  34
  35 static inline MonoBitSet*
  36 mono_bitset_mp_new_noinit (MonoMemPool *mp,  guint32 max_size)
  37 {
  38         int size = mono_bitset_alloc_size (max_size, 0);
  39         gpointer mem;
  40
  41         mem = mono_mempool_alloc (mp, size);
  42         return mono_bitset_mem_new (mem, max_size, MONO_BITSET_DONT_FREE);
  43 }
  44
  45 /*
  46  * Replaces ins with optimized opcodes.
  47  *
  48  * We can emit to cbb the equivalent instructions which will be used as
  49  * replacement for ins, or simply change the fields of ins. Spec needs to
  50  * be updated if we silently change the opcode of ins.
  51  *
  52  * Returns TRUE if additional vregs were allocated.
  53  */
  54 static gboolean
  55 mono_strength_reduction_ins (MonoCompile *cfg, MonoInst *ins, const char **spec)
  56 {
  57         gboolean allocated_vregs = FALSE;
  58
  59         /* FIXME: Add long/float */
  60         switch (ins->opcode) {
  61         case OP_MOVE:
  62         case OP_XMOVE:
  63                 if (ins->dreg == ins->sreg1) {
  64                         NULLIFY_INS (ins);
  65                 }
  66                 break;
  67         case OP_ADD_IMM:
  68         case OP_IADD_IMM:
  69         case OP_SUB_IMM:
  70         case OP_ISUB_IMM:
  71 #if SIZEOF_REGISTER == 8
  72         case OP_LADD_IMM:
  73         case OP_LSUB_IMM:
  74 #endif
  75                 if (ins->inst_imm == 0) {
  76                         ins->opcode = OP_MOVE;
  77                 }
  78                 break;
  79         case OP_MUL_IMM:
  80         case OP_IMUL_IMM:
  81 #if SIZEOF_REGISTER == 8
  82         case OP_LMUL_IMM:
  83 #endif
  84                 if (ins->inst_imm == 0) {
  85                         ins->opcode = (ins->opcode == OP_LMUL_IMM) ? OP_I8CONST : OP_ICONST;
  86                         ins->inst_c0 = 0;
  87                         ins->sreg1 = -1;
  88                 } else if (ins->inst_imm == 1) {
  89                         ins->opcode = OP_MOVE;
  90                 } else if ((ins->opcode == OP_IMUL_IMM) && (ins->inst_imm == -1)) {
  91                         ins->opcode = OP_INEG;
  92                 } else if ((ins->opcode == OP_LMUL_IMM) && (ins->inst_imm == -1)) {
  93                         ins->opcode = OP_LNEG;
  94                 } else {
  95                         int power2 = mono_is_power_of_two (ins->inst_imm);
  96                         if (power2 >= 0) {
  97                                 ins->opcode = (ins->opcode == OP_MUL_IMM) ? OP_SHL_IMM : ((ins->opcode == OP_LMUL_IMM) ? OP_LSHL_IMM : OP_ISHL_IMM);
  98                                 ins->inst_imm = power2;
  99                         }
 100                 }
 101                 break;
 102         case OP_IREM_UN_IMM:
 103         case OP_IDIV_UN_IMM: {
 104                 int c = ins->inst_imm;
 105                 int power2 = mono_is_power_of_two (c);
 106
 107                 if (power2 >= 0) {
 108                         if (ins->opcode == OP_IREM_UN_IMM) {
 109                                 ins->opcode = OP_IAND_IMM;
 110                                 ins->sreg2 = -1;
 111                                 ins->inst_imm = (1 << power2) - 1;
 112                         } else if (ins->opcode == OP_IDIV_UN_IMM) {
 113                                 ins->opcode = OP_ISHR_UN_IMM;
 114                                 ins->sreg2 = -1;
 115                                 ins->inst_imm = power2;
 116                         }
 117                 }
 118                 break;
 119         }
 120         case OP_IDIV_IMM: {
 121                 int c = ins->inst_imm;
 122                 int power2 = mono_is_power_of_two (c);
 123
 124                 if (power2 == 1) {
 125                         int r1 = mono_alloc_ireg (cfg);
 126
 127                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_UN_IMM, r1, ins->sreg1, 31);
 128                         MONO_EMIT_NEW_BIALU (cfg, OP_IADD, r1, r1, ins->sreg1);
 129                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_IMM, ins->dreg, r1, 1);
 130
 131                         allocated_vregs = TRUE;
 132                 } else if (power2 > 0 && power2 < 31) {
 133                         int r1 = mono_alloc_ireg (cfg);
 134
 135                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_IMM, r1, ins->sreg1, 31);
 136                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_UN_IMM, r1, r1, (32 - power2));
 137                         MONO_EMIT_NEW_BIALU (cfg, OP_IADD, r1, r1, ins->sreg1);
 138                         MONO_EMIT_NEW_BIALU_IMM (cfg, OP_ISHR_IMM, ins->dreg, r1, power2);
 139
 140                         allocated_vregs = TRUE;
 141                 }
 142                 break;
 143         }
 144 #if SIZEOF_REGISTER == 8
 145         case OP_LREM_IMM:
 146 #endif
 147         case OP_IREM_IMM: {
 148                 int power = mono_is_power_of_two (ins->inst_imm);
 149                 if (ins->inst_imm == 1) {
 150                         ins->opcode = OP_ICONST;
 151                         MONO_INST_NULLIFY_SREGS (ins);
 152                         ins->inst_c0 = 0;
 153 #if __s390__
 154                 }
 155 #else
 156                 } else if ((ins->inst_imm > 0) && (ins->inst_imm < (1LL << 32)) && (power != -1)) {
 157                         gboolean is_long = ins->opcode == OP_LREM_IMM;
 158                         int compensator_reg = alloc_ireg (cfg);
 159                         int intermediate_reg;
 160
 161                         /* Based on gcc code */
 162
 163                         /* Add compensation for negative numerators */
 164
 165                         if (power > 1) {
 166                                 intermediate_reg = compensator_reg;
 167                                 MONO_EMIT_NEW_BIALU_IMM (cfg, is_long ? OP_LSHR_IMM : OP_ISHR_IMM, intermediate_reg, ins->sreg1, is_long ? 63 : 31);
 168                         } else {
 169                                 intermediate_reg = ins->sreg1;
 170                         }
 171
 172                         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);
 173                         MONO_EMIT_NEW_BIALU (cfg, is_long ? OP_LADD : OP_IADD, ins->dreg, ins->sreg1, compensator_reg);
 174                         /* Compute remainder */
 175                         MONO_EMIT_NEW_BIALU_IMM (cfg, is_long ? OP_LAND_IMM : OP_AND_IMM, ins->dreg, ins->dreg, (1 << power) - 1);
 176                         /* Remove compensation */
 177                         MONO_EMIT_NEW_BIALU (cfg, is_long ? OP_LSUB : OP_ISUB, ins->dreg, ins->dreg, compensator_reg);
 178
 179                         allocated_vregs = TRUE;
 180                 }
 181 #endif
 182                 break;
 183         }
 184
 185         default:
 186                 break;
 187         }
 188
 189         *spec = INS_INFO (ins->opcode);
 190         return allocated_vregs;
 191 }
 192
 193 /*
 194  * mono_local_cprop:
 195  *
 196  *  A combined local copy and constant propagation pass.
 197  */
 198 void
 199 mono_local_cprop (MonoCompile *cfg)
 200 {
 201         MonoBasicBlock *bb, *bb_opt;
 202         MonoInst **defs;
 203         gint32 *def_index;
 204         int max;
 205         int filter = FILTER_IL_SEQ_POINT;
 206         int initial_max_vregs = cfg->next_vreg;
 207
 208         max = cfg->next_vreg;
 209         defs = (MonoInst **)mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * cfg->next_vreg);
 210         def_index = (gint32 *)mono_mempool_alloc (cfg->mempool, sizeof (guint32) * cfg->next_vreg);
 211         cfg->cbb = bb_opt = mono_mempool_alloc0 ((cfg)->mempool, sizeof (MonoBasicBlock));
 212
 213         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 214                 MonoInst *ins;
 215                 int ins_index;
 216                 int last_call_index;
 217
 218                 /* Manually init the defs entries used by the bblock */
 219                 MONO_BB_FOR_EACH_INS (bb, ins) {
 220                         int sregs [MONO_MAX_SRC_REGS];
 221                         int num_sregs, i;
 222
 223                         if (ins->dreg != -1) {
 224 #if SIZEOF_REGISTER == 4
 225                                 const char *spec = INS_INFO (ins->opcode);
 226                                 if (spec [MONO_INST_DEST] == 'l') {
 227                                         defs [ins->dreg + 1] = NULL;
 228                                         defs [ins->dreg + 2] = NULL;
 229                                 }
 230 #endif
 231                                 defs [ins->dreg] = NULL;
 232                         }
 233
 234                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 235                         for (i = 0; i < num_sregs; ++i) {
 236                                 int sreg = sregs [i];
 237 #if SIZEOF_REGISTER == 4
 238                                 const char *spec = INS_INFO (ins->opcode);
 239                                 if (spec [MONO_INST_SRC1 + i] == 'l') {
 240                                         defs [sreg + 1] = NULL;
 241                                         defs [sreg + 2] = NULL;
 242                                 }
 243 #endif
 244                                 defs [sreg] = NULL;
 245                         }
 246                 }
 247
 248                 ins_index = 0;
 249                 last_call_index = -1;
 250                 MONO_BB_FOR_EACH_INS (bb, ins) {
 251                         const char *spec = INS_INFO (ins->opcode);
 252                         int regtype, srcindex, sreg;
 253                         int num_sregs;
 254                         int sregs [MONO_MAX_SRC_REGS];
 255
 256                         if (ins->opcode == OP_NOP) {
 257                                 MONO_DELETE_INS (bb, ins);
 258                                 continue;
 259                         }
 260
 261                         g_assert (ins->opcode > MONO_CEE_LAST);
 262
 263                         /* FIXME: Optimize this */
 264                         if (ins->opcode == OP_LDADDR) {
 265                                 MonoInst *var = (MonoInst *)ins->inst_p0;
 266
 267                                 defs [var->dreg] = NULL;
 268                                 /*
 269                                 if (!MONO_TYPE_ISSTRUCT (var->inst_vtype))
 270                                         break;
 271                                 */
 272                         }
 273
 274                         if (MONO_IS_STORE_MEMBASE (ins)) {
 275                                 sreg = ins->dreg;
 276                                 regtype = 'i';
 277
 278                                 if ((regtype == 'i') && (sreg != -1) && defs [sreg]) {
 279                                         MonoInst *def = defs [sreg];
 280
 281                                         if ((def->opcode == OP_MOVE) && (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) && !vreg_is_volatile (cfg, def->sreg1)) {
 282                                                 int vreg = def->sreg1;
 283                                                 if (cfg->verbose_level > 2) printf ("CCOPY: R%d -> R%d\n", sreg, vreg);
 284                                                 ins->dreg = vreg;
 285                                         }
 286                                 }
 287                         }
 288
 289                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 290                         for (srcindex = 0; srcindex < num_sregs; ++srcindex) {
 291                                 MonoInst *def;
 292
 293                                 mono_inst_get_src_registers (ins, sregs);
 294
 295                                 regtype = spec [MONO_INST_SRC1 + srcindex];
 296                                 sreg = sregs [srcindex];
 297
 298                                 if ((regtype == ' ') || (sreg == -1) || (!defs [sreg]))
 299                                         continue;
 300
 301                                 def = defs [sreg];
 302
 303                                 /* Copy propagation */
 304                                 /*
 305                                  * The first check makes sure the source of the copy did not change since
 306                                  * the copy was made.
 307                                  * The second check avoids volatile variables.
 308                                  * The third check avoids copy propagating local vregs through a call,
 309                                  * since the lvreg will be spilled
 310                                  * The fourth check avoids copy propagating a vreg in cases where
 311                                  * it would be eliminated anyway by reverse copy propagation later,
 312                                  * because propagating it would create another use for it, thus making
 313                                  * it impossible to use reverse copy propagation.
 314                                  */
 315                                 /* Enabling this for floats trips up the fp stack */
 316                                 /*
 317                                  * Enabling this for floats on amd64 seems to cause a failure in
 318                                  * basic-math.cs, most likely because it gets rid of some r8->r4
 319                                  * conversions.
 320                                  */
 321                                 if (MONO_IS_MOVE (def) &&
 322                                         (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg])) &&
 323                                         !vreg_is_volatile (cfg, def->sreg1) &&
 324                                         /* This avoids propagating local vregs across calls */
 325                                         ((get_vreg_to_inst (cfg, def->sreg1) || !defs [def->sreg1] || (def_index [def->sreg1] >= last_call_index) || (def->opcode == OP_VMOVE))) &&
 326                                         !(defs [def->sreg1] && mono_inst_next (defs [def->sreg1], filter) == def) &&
 327                                         (!MONO_ARCH_USE_FPSTACK || (def->opcode != OP_FMOVE)) &&
 328                                         (def->opcode != OP_FMOVE)) {
 329                                         int vreg = def->sreg1;
 330
 331                                         if (cfg->verbose_level > 2) printf ("CCOPY/2: R%d -> R%d\n", sreg, vreg);
 332                                         sregs [srcindex] = vreg;
 333                                         mono_inst_set_src_registers (ins, sregs);
 334
 335                                         /* Allow further iterations */
 336                                         srcindex = -1;
 337                                         continue;
 338                                 }
 339
 340                                 /* Constant propagation */
 341                                 /* FIXME: Make is_inst_imm a macro */
 342                                 /* FIXME: Make is_inst_imm take an opcode argument */
 343                                 /* is_inst_imm is only needed for binops */
 344                                 if ((((def->opcode == OP_ICONST) || ((sizeof (gpointer) == 8) && (def->opcode == OP_I8CONST))) &&
 345                                          (((srcindex == 0) && (ins->sreg2 == -1)) || mono_arch_is_inst_imm (def->inst_c0))) ||
 346                                         (!MONO_ARCH_USE_FPSTACK && (def->opcode == OP_R8CONST))) {
 347                                         guint32 opcode2;
 348
 349                                         /* srcindex == 1 -> binop, ins->sreg2 == -1 -> unop */
 350                                         if ((srcindex == 1) && (ins->sreg1 != -1) && defs [ins->sreg1] && (defs [ins->sreg1]->opcode == OP_ICONST) && defs [ins->sreg2]) {
 351                                                 /* Both arguments are constants, perform cfold */
 352                                                 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
 353                                         } else if ((srcindex == 0) && (ins->sreg2 != -1) && defs [ins->sreg2]) {
 354                                                 /* Arg 1 is constant, swap arguments if possible */
 355                                                 int opcode = ins->opcode;
 356                                                 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], defs [ins->sreg2], TRUE);
 357                                                 if (ins->opcode != opcode) {
 358                                                         /* Allow further iterations */
 359                                                         srcindex = -1;
 360                                                         continue;
 361                                                 }
 362                                         } else if ((srcindex == 0) && (ins->sreg2 == -1)) {
 363                                                 /* Constant unop, perform cfold */
 364                                                 mono_constant_fold_ins (cfg, ins, defs [ins->sreg1], NULL, TRUE);
 365                                         }
 366
 367                                         opcode2 = mono_op_to_op_imm (ins->opcode);
 368                                         if ((opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0) && ((srcindex == 1) || (ins->sreg2 == -1))) {
 369                                                 ins->opcode = opcode2;
 370                                                 if ((def->opcode == OP_I8CONST) && (sizeof (gpointer) == 4)) {
 371                                                         ins->inst_ls_word = def->inst_ls_word;
 372                                                         ins->inst_ms_word = def->inst_ms_word;
 373                                                 } else {
 374                                                         ins->inst_imm = def->inst_c0;
 375                                                 }
 376                                                 sregs [srcindex] = -1;
 377                                                 mono_inst_set_src_registers (ins, sregs);
 378
 379                                                 if ((opcode2 == OP_VOIDCALL) || (opcode2 == OP_CALL) || (opcode2 == OP_LCALL) || (opcode2 == OP_FCALL))
 380                                                         ((MonoCallInst*)ins)->fptr = (gpointer)ins->inst_imm;
 381
 382                                                 /* Allow further iterations */
 383                                                 srcindex = -1;
 384                                                 continue;
 385                                         }
 386                                         else {
 387                                                 /* Special cases */
 388 #if defined(TARGET_X86) || defined(TARGET_AMD64)
 389                                                 if ((ins->opcode == OP_X86_LEA) && (srcindex == 1)) {
 390 #if SIZEOF_REGISTER == 8
 391                                                         /* FIXME: Use OP_PADD_IMM when the new JIT is done */
 392                                                         ins->opcode = OP_LADD_IMM;
 393 #else
 394                                                         ins->opcode = OP_ADD_IMM;
 395 #endif
 396                                                         ins->inst_imm += def->inst_c0 << ins->backend.shift_amount;
 397                                                         ins->sreg2 = -1;
 398                                                 }
 399 #endif
 400                                                 opcode2 = mono_load_membase_to_load_mem (ins->opcode);
 401                                                 if ((srcindex == 0) && (opcode2 != -1) && mono_arch_is_inst_imm (def->inst_c0)) {
 402                                                         ins->opcode = opcode2;
 403                                                         ins->inst_imm = def->inst_c0 + ins->inst_offset;
 404                                                         ins->sreg1 = -1;
 405                                                 }
 406                                         }
 407                                 }
 408                                 else if (((def->opcode == OP_ADD_IMM) || (def->opcode == OP_LADD_IMM)) && (MONO_IS_LOAD_MEMBASE (ins) || MONO_ARCH_IS_OP_MEMBASE (ins->opcode))) {
 409                                         /* ADD_IMM is created by spill_global_vars */
 410                                         /*
 411                                          * We have to guarantee that def->sreg1 haven't changed since def->dreg
 412                                          * was defined. cfg->frame_reg is assumed to remain constant.
 413                                          */
 414                                         if ((def->sreg1 == cfg->frame_reg) || ((mono_inst_next (def, filter) == ins) && (def->dreg != def->sreg1))) {
 415                                                 ins->inst_basereg = def->sreg1;
 416                                                 ins->inst_offset += def->inst_imm;
 417                                         }
 418                                 } else if ((ins->opcode == OP_ISUB_IMM) && (def->opcode == OP_IADD_IMM) && (mono_inst_next (def, filter) == ins) && (def->dreg != def->sreg1)) {
 419                                         ins->sreg1 = def->sreg1;
 420                                         ins->inst_imm -= def->inst_imm;
 421                                 } else if ((ins->opcode == OP_IADD_IMM) && (def->opcode == OP_ISUB_IMM) && (mono_inst_next (def, filter) == ins) && (def->dreg != def->sreg1)) {
 422                                         ins->sreg1 = def->sreg1;
 423                                         ins->inst_imm -= def->inst_imm;
 424                                 } else if (ins->opcode == OP_STOREI1_MEMBASE_REG &&
 425                                                    (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)) &&
 426                                                    (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
 427                                         /* Avoid needless sign extension */
 428                                         ins->sreg1 = def->sreg1;
 429                                 } else if (ins->opcode == OP_STOREI2_MEMBASE_REG &&
 430                                                    (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)) &&
 431                                                    (!defs [def->sreg1] || (def_index [def->sreg1] < def_index [sreg]))) {
 432                                         /* Avoid needless sign extension */
 433                                         ins->sreg1 = def->sreg1;
 434                                 } else if (ins->opcode == OP_COMPARE_IMM && def->opcode == OP_LDADDR && ins->inst_imm == 0) {
 435                                         MonoInst dummy_arg1;
 436
 437                                         memset (&dummy_arg1, 0, sizeof (MonoInst));
 438                                         dummy_arg1.opcode = OP_ICONST;
 439                                         dummy_arg1.inst_c0 = 1;
 440
 441                                         mono_constant_fold_ins (cfg, ins, &dummy_arg1, NULL, TRUE);
 442                                 }
 443                         }
 444
 445                         g_assert (cfg->cbb == bb_opt);
 446                         g_assert (!bb_opt->code);
 447                         /* Do strength reduction here */
 448                         if (mono_strength_reduction_ins (cfg, ins, &spec) && max < cfg->next_vreg) {
 449                                 MonoInst **defs_prev = defs;
 450                                 gint32 *def_index_prev = def_index;
 451                                 guint32 prev_max = max;
 452                                 guint32 additional_vregs = cfg->next_vreg - initial_max_vregs;
 453
 454                                 /* We have more vregs so we need to reallocate defs and def_index arrays */
 455                                 max  = initial_max_vregs + additional_vregs * 2;
 456                                 defs = (MonoInst **)mono_mempool_alloc (cfg->mempool, sizeof (MonoInst*) * max);
 457                                 def_index = (gint32 *)mono_mempool_alloc (cfg->mempool, sizeof (guint32) * max);
 458
 459                                 /* Keep the entries for the previous vregs, zero the rest */
 460                                 memcpy (defs, defs_prev, sizeof (MonoInst*) * prev_max);
 461                                 memset (defs + prev_max, 0, sizeof (MonoInst*) * (max - prev_max));
 462                                 memcpy (def_index, def_index_prev, sizeof (guint32) * prev_max);
 463                                 memset (def_index + prev_max, 0, sizeof (guint32) * (max - prev_max));
 464                         }
 465
 466                         if (cfg->cbb->code || (cfg->cbb != bb_opt)) {
 467                                 MonoInst *saved_prev = ins->prev;
 468
 469                                 /* If we have code in cbb, we need to replace ins with the decomposition */
 470                                 mono_replace_ins (cfg, bb, ins, &ins->prev, bb_opt, cfg->cbb);
 471                                 bb_opt->code = bb_opt->last_ins = NULL;
 472                                 bb_opt->in_count = bb_opt->out_count = 0;
 473                                 cfg->cbb = bb_opt;
 474
 475                                 /* ins is hanging, continue scanning the emitted code */
 476                                 ins = saved_prev;
 477                                 continue;
 478                         }
 479
 480                         if (spec [MONO_INST_DEST] != ' ') {
 481                                 MonoInst *def = defs [ins->dreg];
 482
 483                                 if (def && (def->opcode == OP_ADD_IMM) && (def->sreg1 == cfg->frame_reg) && (MONO_IS_STORE_MEMBASE (ins))) {
 484                                         /* ADD_IMM is created by spill_global_vars */
 485                                         /* cfg->frame_reg is assumed to remain constant */
 486                                         ins->inst_destbasereg = def->sreg1;
 487                                         ins->inst_offset += def->inst_imm;
 488                                 }
 489                         }
 490
 491                         if ((spec [MONO_INST_DEST] != ' ') && !MONO_IS_STORE_MEMBASE (ins) && !vreg_is_volatile (cfg, ins->dreg)) {
 492                                 defs [ins->dreg] = ins;
 493                                 def_index [ins->dreg] = ins_index;
 494                         }
 495
 496                         if (MONO_IS_CALL (ins))
 497                                 last_call_index = ins_index;
 498
 499                         ins_index ++;
 500                 }
 501         }
 502 }
 503
 504 static inline gboolean
 505 reg_is_softreg_no_fpstack (int reg, const char spec)
 506 {
 507         return (spec == 'i' && reg >= MONO_MAX_IREGS)
 508                 || ((spec == 'f' && reg >= MONO_MAX_FREGS) && !MONO_ARCH_USE_FPSTACK)
 509 #ifdef MONO_ARCH_SIMD_INTRINSICS
 510                 || (spec == 'x' && reg >= MONO_MAX_XREGS)
 511 #endif
 512                 || (spec == 'v');
 513 }
 514
 515 static inline gboolean
 516 reg_is_softreg (int reg, const char spec)
 517 {
 518         return (spec == 'i' && reg >= MONO_MAX_IREGS)
 519                 || (spec == 'f' && reg >= MONO_MAX_FREGS)
 520 #ifdef MONO_ARCH_SIMD_INTRINSICS
 521                 || (spec == 'x' && reg >= MONO_MAX_XREGS)
 522 #endif
 523                 || (spec == 'v');
 524 }
 525
 526 static inline gboolean
 527 mono_is_simd_accessor (MonoInst *ins)
 528 {
 529         switch (ins->opcode) {
 530 #ifdef MONO_ARCH_SIMD_INTRINSICS
 531         case OP_INSERT_I1:
 532         case OP_INSERT_I2:
 533         case OP_INSERT_I4:
 534         case OP_INSERT_I8:
 535         case OP_INSERT_R4:
 536         case OP_INSERT_R8:
 537
 538         case OP_INSERTX_U1_SLOW:
 539         case OP_INSERTX_I4_SLOW:
 540         case OP_INSERTX_R4_SLOW:
 541         case OP_INSERTX_R8_SLOW:
 542         case OP_INSERTX_I8_SLOW:
 543                 return TRUE;
 544 #endif
 545         default:
 546                 return FALSE;
 547         }
 548 }
 549
 550 /**
 551  * mono_local_deadce:
 552  *
 553  *   Get rid of the dead assignments to local vregs like the ones created by the
 554  * copyprop pass.
 555  */
 556 void
 557 mono_local_deadce (MonoCompile *cfg)
 558 {
 559         MonoBasicBlock *bb;
 560         MonoInst *ins, *prev;
 561         MonoBitSet *used, *defined;
 562
 563         //mono_print_code (cfg, "BEFORE LOCAL-DEADCE");
 564
 565         /*
 566          * Assignments to global vregs can't be eliminated so this pass must come
 567          * after the handle_global_vregs () pass.
 568          */
 569
 570         used = mono_bitset_mp_new_noinit (cfg->mempool, cfg->next_vreg + 1);
 571         defined = mono_bitset_mp_new_noinit (cfg->mempool, cfg->next_vreg + 1);
 572
 573         /* First pass: collect liveness info */
 574         for (bb = cfg->bb_entry; bb; bb = bb->next_bb) {
 575                 /* Manually init the defs entries used by the bblock */
 576                 MONO_BB_FOR_EACH_INS (bb, ins) {
 577                         const char *spec = INS_INFO (ins->opcode);
 578                         int sregs [MONO_MAX_SRC_REGS];
 579                         int num_sregs, i;
 580
 581                         if (spec [MONO_INST_DEST] != ' ') {
 582                                 mono_bitset_clear_fast (used, ins->dreg);
 583                                 mono_bitset_clear_fast (defined, ins->dreg);
 584 #if SIZEOF_REGISTER == 4
 585                                 /* Regpairs */
 586                                 mono_bitset_clear_fast (used, ins->dreg + 1);
 587                                 mono_bitset_clear_fast (defined, ins->dreg + 1);
 588 #endif
 589                         }
 590                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 591                         for (i = 0; i < num_sregs; ++i) {
 592                                 mono_bitset_clear_fast (used, sregs [i]);
 593 #if SIZEOF_REGISTER == 4
 594                                 mono_bitset_clear_fast (used, sregs [i] + 1);
 595 #endif
 596                         }
 597                 }
 598
 599                 /*
 600                  * Make a reverse pass over the instruction list
 601                  */
 602                 MONO_BB_FOR_EACH_INS_REVERSE_SAFE (bb, prev, ins) {
 603                         const char *spec = INS_INFO (ins->opcode);
 604                         int sregs [MONO_MAX_SRC_REGS];
 605                         int num_sregs, i;
 606                         MonoInst *prev_f = mono_inst_prev (ins, FILTER_NOP | FILTER_IL_SEQ_POINT);
 607
 608                         if (ins->opcode == OP_NOP) {
 609                                 MONO_DELETE_INS (bb, ins);
 610                                 continue;
 611                         }
 612
 613                         g_assert (ins->opcode > MONO_CEE_LAST);
 614
 615                         if (MONO_IS_NON_FP_MOVE (ins) && prev_f) {
 616                                 MonoInst *def;
 617                                 const char *spec2;
 618
 619                                 def = prev_f;
 620                                 spec2 = INS_INFO (def->opcode);
 621
 622                                 /*
 623                                  * Perform a limited kind of reverse copy propagation, i.e.
 624                                  * transform B <- FOO; A <- B into A <- FOO
 625                                  * This isn't copyprop, not deadce, but it can only be performed
 626                                  * after handle_global_vregs () has run.
 627                                  */
 628                                 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)) {
 629                                         if (cfg->verbose_level > 2) {
 630                                                 printf ("\tReverse copyprop in BB%d on ", bb->block_num);
 631                                                 mono_print_ins (ins);
 632                                         }
 633
 634                                         def->dreg = ins->dreg;
 635                                         MONO_DELETE_INS (bb, ins);
 636                                         spec = INS_INFO (ins->opcode);
 637                                 }
 638                         }
 639
 640                         /* Enabling this on x86 could screw up the fp stack */
 641                         if (reg_is_softreg_no_fpstack (ins->dreg, spec [MONO_INST_DEST])) {
 642                                 /*
 643                                  * Assignments to global vregs can only be eliminated if there is another
 644                                  * assignment to the same vreg later in the same bblock.
 645                                  */
 646                                 if (!mono_bitset_test_fast (used, ins->dreg) &&
 647                                         (!get_vreg_to_inst (cfg, ins->dreg) || (!bb->extended && !vreg_is_volatile (cfg, ins->dreg) && mono_bitset_test_fast (defined, ins->dreg))) &&
 648                                         MONO_INS_HAS_NO_SIDE_EFFECT (ins)) {
 649                                         /* Happens with CMOV instructions */
 650                                         if (prev_f && prev_f->opcode == OP_ICOMPARE_IMM) {
 651                                                 MonoInst *prev = prev_f;
 652                                                 /*
 653                                                  * Can't use DELETE_INS since that would interfere with the
 654                                                  * FOR_EACH_INS loop.
 655                                                  */
 656                                                 NULLIFY_INS (prev);
 657                                         }
 658                                         //printf ("DEADCE: "); mono_print_ins (ins);
 659                                         MONO_DELETE_INS (bb, ins);
 660                                         spec = INS_INFO (ins->opcode);
 661                                 }
 662
 663                                 if (spec [MONO_INST_DEST] != ' ')
 664                                         mono_bitset_clear_fast (used, ins->dreg);
 665                         }
 666
 667                         if (spec [MONO_INST_DEST] != ' ')
 668                                 mono_bitset_set_fast (defined, ins->dreg);
 669                         num_sregs = mono_inst_get_src_registers (ins, sregs);
 670                         for (i = 0; i < num_sregs; ++i)
 671                                 mono_bitset_set_fast (used, sregs [i]);
 672                         if (MONO_IS_STORE_MEMBASE (ins))
 673                                 mono_bitset_set_fast (used, ins->dreg);
 674
 675                         if (MONO_IS_CALL (ins)) {
 676                                 MonoCallInst *call = (MonoCallInst*)ins;
 677                                 GSList *l;
 678
 679                                 if (call->out_ireg_args) {
 680                                         for (l = call->out_ireg_args; l; l = l->next) {
 681                                                 guint32 regpair, reg;
 682
 683                                                 regpair = (guint32)(gssize)(l->data);
 684                                                 reg = regpair & 0xffffff;
 685
 686                                                 mono_bitset_set_fast (used, reg);
 687                                         }
 688                                 }
 689
 690                                 if (call->out_freg_args) {
 691                                         for (l = call->out_freg_args; l; l = l->next) {
 692                                                 guint32 regpair, reg;
 693
 694                                                 regpair = (guint32)(gssize)(l->data);
 695                                                 reg = regpair & 0xffffff;
 696
 697                                                 mono_bitset_set_fast (used, reg);
 698                                         }
 699                                 }
 700                         }
 701                 }
 702         }
 703
 704         //mono_print_code (cfg, "AFTER LOCAL-DEADCE");
 705 }
 706
 707 #endif /* DISABLE_JIT */