gcc/mode-switching.c

   1 /* CPU mode switching
   2    Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2007
   3    Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "rtl.h"
  26 #include "regs.h"
  27 #include "hard-reg-set.h"
  28 #include "flags.h"
  29 #include "real.h"
  30 #include "insn-config.h"
  31 #include "recog.h"
  32 #include "basic-block.h"
  33 #include "output.h"
  34 #include "tm_p.h"
  35 #include "function.h"
  36 #include "tree-pass.h"
  37 #include "timevar.h"
  38 #include "df.h"
  39
  40 /* We want target macros for the mode switching code to be able to refer
  41    to instruction attribute values.  */
  42 #include "insn-attr.h"
  43
  44 #ifdef OPTIMIZE_MODE_SWITCHING
  45
  46 /* The algorithm for setting the modes consists of scanning the insn list
  47    and finding all the insns which require a specific mode.  Each insn gets
  48    a unique struct seginfo element.  These structures are inserted into a list
  49    for each basic block.  For each entity, there is an array of bb_info over
  50    the flow graph basic blocks (local var 'bb_info'), and contains a list
  51    of all insns within that basic block, in the order they are encountered.
  52
  53    For each entity, any basic block WITHOUT any insns requiring a specific
  54    mode are given a single entry, without a mode.  (Each basic block
  55    in the flow graph must have at least one entry in the segment table.)
  56
  57    The LCM algorithm is then run over the flow graph to determine where to
  58    place the sets to the highest-priority value in respect of first the first
  59    insn in any one block.  Any adjustments required to the transparency
  60    vectors are made, then the next iteration starts for the next-lower
  61    priority mode, till for each entity all modes are exhausted.
  62
  63    More details are located in the code for optimize_mode_switching().  */
  64 \f
  65 /* This structure contains the information for each insn which requires
  66    either single or double mode to be set.
  67    MODE is the mode this insn must be executed in.
  68    INSN_PTR is the insn to be executed (may be the note that marks the
  69    beginning of a basic block).
  70    BBNUM is the flow graph basic block this insn occurs in.
  71    NEXT is the next insn in the same basic block.  */
  72 struct seginfo
  73 {
  74   int mode;
  75   rtx insn_ptr;
  76   int bbnum;
  77   struct seginfo *next;
  78   HARD_REG_SET regs_live;
  79 };
  80
  81 struct bb_info
  82 {
  83   struct seginfo *seginfo;
  84   int computing;
  85 };
  86
  87 /* These bitmaps are used for the LCM algorithm.  */
  88
  89 static sbitmap *antic;
  90 static sbitmap *transp;
  91 static sbitmap *comp;
  92
  93 static struct seginfo * new_seginfo (int, rtx, int, HARD_REG_SET);
  94 static void add_seginfo (struct bb_info *, struct seginfo *);
  95 static void reg_dies (rtx, HARD_REG_SET *);
  96 static void reg_becomes_live (rtx, const_rtx, void *);
  97 static void make_preds_opaque (basic_block, int);
  98 \f
  99
 100 /* This function will allocate a new BBINFO structure, initialized
 101    with the MODE, INSN, and basic block BB parameters.  */
 102
 103 static struct seginfo *
 104 new_seginfo (int mode, rtx insn, int bb, HARD_REG_SET regs_live)
 105 {
 106   struct seginfo *ptr;
 107   ptr = XNEW (struct seginfo);
 108   ptr->mode = mode;
 109   ptr->insn_ptr = insn;
 110   ptr->bbnum = bb;
 111   ptr->next = NULL;
 112   COPY_HARD_REG_SET (ptr->regs_live, regs_live);
 113   return ptr;
 114 }
 115
 116 /* Add a seginfo element to the end of a list.
 117    HEAD is a pointer to the list beginning.
 118    INFO is the structure to be linked in.  */
 119
 120 static void
 121 add_seginfo (struct bb_info *head, struct seginfo *info)
 122 {
 123   struct seginfo *ptr;
 124
 125   if (head->seginfo == NULL)
 126     head->seginfo = info;
 127   else
 128     {
 129       ptr = head->seginfo;
 130       while (ptr->next != NULL)
 131         ptr = ptr->next;
 132       ptr->next = info;
 133     }
 134 }
 135
 136 /* Make all predecessors of basic block B opaque, recursively, till we hit
 137    some that are already non-transparent, or an edge where aux is set; that
 138    denotes that a mode set is to be done on that edge.
 139    J is the bit number in the bitmaps that corresponds to the entity that
 140    we are currently handling mode-switching for.  */
 141
 142 static void
 143 make_preds_opaque (basic_block b, int j)
 144 {
 145   edge e;
 146   edge_iterator ei;
 147
 148   FOR_EACH_EDGE (e, ei, b->preds)
 149     {
 150       basic_block pb = e->src;
 151
 152       if (e->aux || ! TEST_BIT (transp[pb->index], j))
 153         continue;
 154
 155       RESET_BIT (transp[pb->index], j);
 156       make_preds_opaque (pb, j);
 157     }
 158 }
 159
 160 /* Record in LIVE that register REG died.  */
 161
 162 static void
 163 reg_dies (rtx reg, HARD_REG_SET *live)
 164 {
 165   int regno;
 166
 167   if (!REG_P (reg))
 168     return;
 169
 170   regno = REGNO (reg);
 171   if (regno < FIRST_PSEUDO_REGISTER)
 172     remove_from_hard_reg_set (live, GET_MODE (reg), regno);
 173 }
 174
 175 /* Record in LIVE that register REG became live.
 176    This is called via note_stores.  */
 177
 178 static void
 179 reg_becomes_live (rtx reg, const_rtx setter ATTRIBUTE_UNUSED, void *live)
 180 {
 181   int regno;
 182
 183   if (GET_CODE (reg) == SUBREG)
 184     reg = SUBREG_REG (reg);
 185
 186   if (!REG_P (reg))
 187     return;
 188
 189   regno = REGNO (reg);
 190   if (regno < FIRST_PSEUDO_REGISTER)
 191     add_to_hard_reg_set ((HARD_REG_SET *) live, GET_MODE (reg), regno);
 192 }
 193
 194 /* Make sure if MODE_ENTRY is defined the MODE_EXIT is defined
 195    and vice versa.  */
 196 #if defined (MODE_ENTRY) != defined (MODE_EXIT)
 197  #error "Both MODE_ENTRY and MODE_EXIT must be defined"
 198 #endif
 199
 200 #if defined (MODE_ENTRY) && defined (MODE_EXIT)
 201 /* Split the fallthrough edge to the exit block, so that we can note
 202    that there NORMAL_MODE is required.  Return the new block if it's
 203    inserted before the exit block.  Otherwise return null.  */
 204
 205 static basic_block
 206 create_pre_exit (int n_entities, int *entity_map, const int *num_modes)
 207 {
 208   edge eg;
 209   edge_iterator ei;
 210   basic_block pre_exit;
 211
 212   /* The only non-call predecessor at this stage is a block with a
 213      fallthrough edge; there can be at most one, but there could be
 214      none at all, e.g. when exit is called.  */
 215   pre_exit = 0;
 216   FOR_EACH_EDGE (eg, ei, EXIT_BLOCK_PTR->preds)
 217     if (eg->flags & EDGE_FALLTHRU)
 218       {
 219         basic_block src_bb = eg->src;
 220         rtx last_insn, ret_reg;
 221
 222         gcc_assert (!pre_exit);
 223         /* If this function returns a value at the end, we have to
 224            insert the final mode switch before the return value copy
 225            to its hard register.  */
 226         if (EDGE_COUNT (EXIT_BLOCK_PTR->preds) == 1
 227             && NONJUMP_INSN_P ((last_insn = BB_END (src_bb)))
 228             && GET_CODE (PATTERN (last_insn)) == USE
 229             && GET_CODE ((ret_reg = XEXP (PATTERN (last_insn), 0))) == REG)
 230           {
 231             int ret_start = REGNO (ret_reg);
 232             int nregs = hard_regno_nregs[ret_start][GET_MODE (ret_reg)];
 233             int ret_end = ret_start + nregs;
 234             int short_block = 0;
 235             int maybe_builtin_apply = 0;
 236             int forced_late_switch = 0;
 237             rtx before_return_copy;
 238
 239             do
 240               {
 241                 rtx return_copy = PREV_INSN (last_insn);
 242                 rtx return_copy_pat, copy_reg;
 243                 int copy_start, copy_num;
 244                 int j;
 245
 246                 if (INSN_P (return_copy))
 247                   {
 248                     /* When using SJLJ exceptions, the call to the
 249                        unregister function is inserted between the
 250                        clobber of the return value and the copy.
 251                        We do not want to split the block before this
 252                        or any other call; if we have not found the
 253                        copy yet, the copy must have been deleted.  */
 254                     if (CALL_P (return_copy))
 255                       {
 256                         short_block = 1;
 257                         break;
 258                       }
 259                     return_copy_pat = PATTERN (return_copy);
 260                     switch (GET_CODE (return_copy_pat))
 261                       {
 262                       case USE:
 263                         /* Skip __builtin_apply pattern.  */
 264                         if (GET_CODE (XEXP (return_copy_pat, 0)) == REG
 265                             && (FUNCTION_VALUE_REGNO_P
 266                                 (REGNO (XEXP (return_copy_pat, 0)))))
 267                           {
 268                             maybe_builtin_apply = 1;
 269                             last_insn = return_copy;
 270                             continue;
 271                           }
 272                         break;
 273
 274                       case ASM_OPERANDS:
 275                         /* Skip barrier insns.  */
 276                         if (!MEM_VOLATILE_P (return_copy_pat))
 277                           break;
 278
 279                         /* Fall through.  */
 280
 281                       case ASM_INPUT:
 282                       case UNSPEC_VOLATILE:
 283                         last_insn = return_copy;
 284                         continue;
 285
 286                       default:
 287                         break;
 288                       }
 289
 290                     /* If the return register is not (in its entirety)
 291                        likely spilled, the return copy might be
 292                        partially or completely optimized away.  */
 293                     return_copy_pat = single_set (return_copy);
 294                     if (!return_copy_pat)
 295                       {
 296                         return_copy_pat = PATTERN (return_copy);
 297                         if (GET_CODE (return_copy_pat) != CLOBBER)
 298                           break;
 299                         else if (!optimize)
 300                           {
 301                             /* This might be (clobber (reg [<result>]))
 302                                when not optimizing.  Then check if
 303                                the previous insn is the clobber for
 304                                the return register.  */
 305                             copy_reg = SET_DEST (return_copy_pat);
 306                             if (GET_CODE (copy_reg) == REG
 307                                 && !HARD_REGISTER_NUM_P (REGNO (copy_reg)))
 308                               {
 309                                 if (INSN_P (PREV_INSN (return_copy)))
 310                                   {
 311                                     return_copy = PREV_INSN (return_copy);
 312                                     return_copy_pat = PATTERN (return_copy);
 313                                     if (GET_CODE (return_copy_pat) != CLOBBER)
 314                                       break;
 315                                   }
 316                               }
 317                           }
 318                       }
 319                     copy_reg = SET_DEST (return_copy_pat);
 320                     if (GET_CODE (copy_reg) == REG)
 321                       copy_start = REGNO (copy_reg);
 322                     else if (GET_CODE (copy_reg) == SUBREG
 323                              && GET_CODE (SUBREG_REG (copy_reg)) == REG)
 324                       copy_start = REGNO (SUBREG_REG (copy_reg));
 325                     else
 326                       break;
 327                     if (copy_start >= FIRST_PSEUDO_REGISTER)
 328                       break;
 329                     copy_num
 330                       = hard_regno_nregs[copy_start][GET_MODE (copy_reg)];
 331
 332                     /* If the return register is not likely spilled, - as is
 333                        the case for floating point on SH4 - then it might
 334                        be set by an arithmetic operation that needs a
 335                        different mode than the exit block.  */
 336                     for (j = n_entities - 1; j >= 0; j--)
 337                       {
 338                         int e = entity_map[j];
 339                         int mode = MODE_NEEDED (e, return_copy);
 340
 341                         if (mode != num_modes[e] && mode != MODE_EXIT (e))
 342                           break;
 343                       }
 344                     if (j >= 0)
 345                       {
 346                         /* For the SH4, floating point loads depend on fpscr,
 347                            thus we might need to put the final mode switch
 348                            after the return value copy.  That is still OK,
 349                            because a floating point return value does not
 350                            conflict with address reloads.  */
 351                         if (copy_start >= ret_start
 352                             && copy_start + copy_num <= ret_end
 353                             && OBJECT_P (SET_SRC (return_copy_pat)))
 354                           forced_late_switch = 1;
 355                         break;
 356                       }
 357
 358                     if (copy_start >= ret_start
 359                         && copy_start + copy_num <= ret_end)
 360                       nregs -= copy_num;
 361                     else if (!maybe_builtin_apply
 362                              || !FUNCTION_VALUE_REGNO_P (copy_start))
 363                       break;
 364                     last_insn = return_copy;
 365                   }
 366                 /* ??? Exception handling can lead to the return value
 367                    copy being already separated from the return value use,
 368                    as in  unwind-dw2.c .
 369                    Similarly, conditionally returning without a value,
 370                    and conditionally using builtin_return can lead to an
 371                    isolated use.  */
 372                 if (return_copy == BB_HEAD (src_bb))
 373                   {
 374                     short_block = 1;
 375                     break;
 376                   }
 377                 last_insn = return_copy;
 378               }
 379             while (nregs);
 380
 381             /* If we didn't see a full return value copy, verify that there
 382                is a plausible reason for this.  If some, but not all of the
 383                return register is likely spilled, we can expect that there
 384                is a copy for the likely spilled part.  */
 385             gcc_assert (!nregs
 386                         || forced_late_switch
 387                         || short_block
 388                         || !(CLASS_LIKELY_SPILLED_P
 389                              (REGNO_REG_CLASS (ret_start)))
 390                         || (nregs
 391                             != hard_regno_nregs[ret_start][GET_MODE (ret_reg)])
 392                         /* For multi-hard-register floating point
 393                            values, sometimes the likely-spilled part
 394                            is ordinarily copied first, then the other
 395                            part is set with an arithmetic operation.
 396                            This doesn't actually cause reload
 397                            failures, so let it pass.  */
 398                         || (GET_MODE_CLASS (GET_MODE (ret_reg)) != MODE_INT
 399                             && nregs != 1));
 400
 401             if (INSN_P (last_insn))
 402               {
 403                 before_return_copy
 404                   = emit_note_before (NOTE_INSN_DELETED, last_insn);
 405                 /* Instructions preceding LAST_INSN in the same block might
 406                    require a different mode than MODE_EXIT, so if we might
 407                    have such instructions, keep them in a separate block
 408                    from pre_exit.  */
 409                 if (last_insn != BB_HEAD (src_bb))
 410                   src_bb = split_block (src_bb,
 411                                         PREV_INSN (before_return_copy))->dest;
 412               }
 413             else
 414               before_return_copy = last_insn;
 415             pre_exit = split_block (src_bb, before_return_copy)->src;
 416           }
 417         else
 418           {
 419             pre_exit = split_edge (eg);
 420           }
 421       }
 422
 423   return pre_exit;
 424 }
 425 #endif
 426
 427 /* Find all insns that need a particular mode setting, and insert the
 428    necessary mode switches.  Return true if we did work.  */
 429
 430 static int
 431 optimize_mode_switching (void)
 432 {
 433   rtx insn;
 434   int e;
 435   basic_block bb;
 436   int need_commit = 0;
 437   sbitmap *kill;
 438   struct edge_list *edge_list;
 439   static const int num_modes[] = NUM_MODES_FOR_MODE_SWITCHING;
 440 #define N_ENTITIES ARRAY_SIZE (num_modes)
 441   int entity_map[N_ENTITIES];
 442   struct bb_info *bb_info[N_ENTITIES];
 443   int i, j;
 444   int n_entities;
 445   int max_num_modes = 0;
 446   bool emited = false;
 447   basic_block post_entry ATTRIBUTE_UNUSED, pre_exit ATTRIBUTE_UNUSED;
 448
 449   for (e = N_ENTITIES - 1, n_entities = 0; e >= 0; e--)
 450     if (OPTIMIZE_MODE_SWITCHING (e))
 451       {
 452         int entry_exit_extra = 0;
 453
 454         /* Create the list of segments within each basic block.
 455            If NORMAL_MODE is defined, allow for two extra
 456            blocks split from the entry and exit block.  */
 457 #if defined (MODE_ENTRY) && defined (MODE_EXIT)
 458         entry_exit_extra = 3;
 459 #endif
 460         bb_info[n_entities]
 461           = XCNEWVEC (struct bb_info, last_basic_block + entry_exit_extra);
 462         entity_map[n_entities++] = e;
 463         if (num_modes[e] > max_num_modes)
 464           max_num_modes = num_modes[e];
 465       }
 466
 467   if (! n_entities)
 468     return 0;
 469
 470 #if defined (MODE_ENTRY) && defined (MODE_EXIT)
 471   /* Split the edge from the entry block, so that we can note that
 472      there NORMAL_MODE is supplied.  */
 473   post_entry = split_edge (single_succ_edge (ENTRY_BLOCK_PTR));
 474   pre_exit = create_pre_exit (n_entities, entity_map, num_modes);
 475 #endif
 476
 477   df_analyze ();
 478
 479   /* Create the bitmap vectors.  */
 480
 481   antic = sbitmap_vector_alloc (last_basic_block, n_entities);
 482   transp = sbitmap_vector_alloc (last_basic_block, n_entities);
 483   comp = sbitmap_vector_alloc (last_basic_block, n_entities);
 484
 485   sbitmap_vector_ones (transp, last_basic_block);
 486
 487   for (j = n_entities - 1; j >= 0; j--)
 488     {
 489       int e = entity_map[j];
 490       int no_mode = num_modes[e];
 491       struct bb_info *info = bb_info[j];
 492
 493       /* Determine what the first use (if any) need for a mode of entity E is.
 494          This will be the mode that is anticipatable for this block.
 495          Also compute the initial transparency settings.  */
 496       FOR_EACH_BB (bb)
 497         {
 498           struct seginfo *ptr;
 499           int last_mode = no_mode;
 500           HARD_REG_SET live_now;
 501
 502           REG_SET_TO_HARD_REG_SET (live_now, df_get_live_in (bb));
 503
 504           /* Pretend the mode is clobbered across abnormal edges.  */
 505           {
 506             edge_iterator ei;
 507             edge e;
 508             FOR_EACH_EDGE (e, ei, bb->preds)
 509               if (e->flags & EDGE_COMPLEX)
 510                 break;
 511             if (e)
 512               {
 513                 ptr = new_seginfo (no_mode, BB_HEAD (bb), bb->index, live_now);
 514                 add_seginfo (info + bb->index, ptr);
 515                 RESET_BIT (transp[bb->index], j);
 516               }
 517           }
 518
 519           for (insn = BB_HEAD (bb);
 520                insn != NULL && insn != NEXT_INSN (BB_END (bb));
 521                insn = NEXT_INSN (insn))
 522             {
 523               if (INSN_P (insn))
 524                 {
 525                   int mode = MODE_NEEDED (e, insn);
 526                   rtx link;
 527
 528                   if (mode != no_mode && mode != last_mode)
 529                     {
 530                       last_mode = mode;
 531                       ptr = new_seginfo (mode, insn, bb->index, live_now);
 532                       add_seginfo (info + bb->index, ptr);
 533                       RESET_BIT (transp[bb->index], j);
 534                     }
 535 #ifdef MODE_AFTER
 536                   last_mode = MODE_AFTER (last_mode, insn);
 537 #endif
 538                   /* Update LIVE_NOW.  */
 539                   for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
 540                     if (REG_NOTE_KIND (link) == REG_DEAD)
 541                       reg_dies (XEXP (link, 0), &live_now);
 542
 543                   note_stores (PATTERN (insn), reg_becomes_live, &live_now);
 544                   for (link = REG_NOTES (insn); link; link = XEXP (link, 1))
 545                     if (REG_NOTE_KIND (link) == REG_UNUSED)
 546                       reg_dies (XEXP (link, 0), &live_now);
 547                 }
 548             }
 549
 550           info[bb->index].computing = last_mode;
 551           /* Check for blocks without ANY mode requirements.  */
 552           if (last_mode == no_mode)
 553             {
 554               ptr = new_seginfo (no_mode, BB_END (bb), bb->index, live_now);
 555               add_seginfo (info + bb->index, ptr);
 556             }
 557         }
 558 #if defined (MODE_ENTRY) && defined (MODE_EXIT)
 559       {
 560         int mode = MODE_ENTRY (e);
 561
 562         if (mode != no_mode)
 563           {
 564             bb = post_entry;
 565
 566             /* By always making this nontransparent, we save
 567                an extra check in make_preds_opaque.  We also
 568                need this to avoid confusing pre_edge_lcm when
 569                antic is cleared but transp and comp are set.  */
 570             RESET_BIT (transp[bb->index], j);
 571
 572             /* Insert a fake computing definition of MODE into entry
 573                blocks which compute no mode. This represents the mode on
 574                entry.  */
 575             info[bb->index].computing = mode;
 576
 577             if (pre_exit)
 578               info[pre_exit->index].seginfo->mode = MODE_EXIT (e);
 579           }
 580       }
 581 #endif /* NORMAL_MODE */
 582     }
 583
 584   kill = sbitmap_vector_alloc (last_basic_block, n_entities);
 585   for (i = 0; i < max_num_modes; i++)
 586     {
 587       int current_mode[N_ENTITIES];
 588       sbitmap *delete;
 589       sbitmap *insert;
 590
 591       /* Set the anticipatable and computing arrays.  */
 592       sbitmap_vector_zero (antic, last_basic_block);
 593       sbitmap_vector_zero (comp, last_basic_block);
 594       for (j = n_entities - 1; j >= 0; j--)
 595         {
 596           int m = current_mode[j] = MODE_PRIORITY_TO_MODE (entity_map[j], i);
 597           struct bb_info *info = bb_info[j];
 598
 599           FOR_EACH_BB (bb)
 600             {
 601               if (info[bb->index].seginfo->mode == m)
 602                 SET_BIT (antic[bb->index], j);
 603
 604               if (info[bb->index].computing == m)
 605                 SET_BIT (comp[bb->index], j);
 606             }
 607         }
 608
 609       /* Calculate the optimal locations for the
 610          placement mode switches to modes with priority I.  */
 611
 612       FOR_EACH_BB (bb)
 613         sbitmap_not (kill[bb->index], transp[bb->index]);
 614       edge_list = pre_edge_lcm (n_entities, transp, comp, antic,
 615                                 kill, &insert, &delete);
 616
 617       for (j = n_entities - 1; j >= 0; j--)
 618         {
 619           /* Insert all mode sets that have been inserted by lcm.  */
 620           int no_mode = num_modes[entity_map[j]];
 621
 622           /* Wherever we have moved a mode setting upwards in the flow graph,
 623              the blocks between the new setting site and the now redundant
 624              computation ceases to be transparent for any lower-priority
 625              mode of the same entity.  First set the aux field of each
 626              insertion site edge non-transparent, then propagate the new
 627              non-transparency from the redundant computation upwards till
 628              we hit an insertion site or an already non-transparent block.  */
 629           for (e = NUM_EDGES (edge_list) - 1; e >= 0; e--)
 630             {
 631               edge eg = INDEX_EDGE (edge_list, e);
 632               int mode;
 633               basic_block src_bb;
 634               HARD_REG_SET live_at_edge;
 635               rtx mode_set;
 636
 637               eg->aux = 0;
 638
 639               if (! TEST_BIT (insert[e], j))
 640                 continue;
 641
 642               eg->aux = (void *)1;
 643
 644               mode = current_mode[j];
 645               src_bb = eg->src;
 646
 647               REG_SET_TO_HARD_REG_SET (live_at_edge, df_get_live_out (src_bb));
 648
 649               start_sequence ();
 650               EMIT_MODE_SET (entity_map[j], mode, live_at_edge);
 651               mode_set = get_insns ();
 652               end_sequence ();
 653
 654               /* Do not bother to insert empty sequence.  */
 655               if (mode_set == NULL_RTX)
 656                 continue;
 657
 658               /* We should not get an abnormal edge here.  */
 659               gcc_assert (! (eg->flags & EDGE_ABNORMAL));
 660
 661               need_commit = 1;
 662               insert_insn_on_edge (mode_set, eg);
 663             }
 664
 665           FOR_EACH_BB_REVERSE (bb)
 666             if (TEST_BIT (delete[bb->index], j))
 667               {
 668                 make_preds_opaque (bb, j);
 669                 /* Cancel the 'deleted' mode set.  */
 670                 bb_info[j][bb->index].seginfo->mode = no_mode;
 671               }
 672         }
 673
 674       sbitmap_vector_free (delete);
 675       sbitmap_vector_free (insert);
 676       clear_aux_for_edges ();
 677       free_edge_list (edge_list);
 678     }
 679
 680   /* Now output the remaining mode sets in all the segments.  */
 681   for (j = n_entities - 1; j >= 0; j--)
 682     {
 683       int no_mode = num_modes[entity_map[j]];
 684
 685       FOR_EACH_BB_REVERSE (bb)
 686         {
 687           struct seginfo *ptr, *next;
 688           for (ptr = bb_info[j][bb->index].seginfo; ptr; ptr = next)
 689             {
 690               next = ptr->next;
 691               if (ptr->mode != no_mode)
 692                 {
 693                   rtx mode_set;
 694
 695                   start_sequence ();
 696                   EMIT_MODE_SET (entity_map[j], ptr->mode, ptr->regs_live);
 697                   mode_set = get_insns ();
 698                   end_sequence ();
 699
 700                   /* Insert MODE_SET only if it is nonempty.  */
 701                   if (mode_set != NULL_RTX)
 702                     {
 703                       emited = true;
 704                       if (NOTE_INSN_BASIC_BLOCK_P (ptr->insn_ptr))
 705                         emit_insn_after (mode_set, ptr->insn_ptr);
 706                       else
 707                         emit_insn_before (mode_set, ptr->insn_ptr);
 708                     }
 709                 }
 710
 711               free (ptr);
 712             }
 713         }
 714
 715       free (bb_info[j]);
 716     }
 717
 718   /* Finished. Free up all the things we've allocated.  */
 719   sbitmap_vector_free (kill);
 720   sbitmap_vector_free (antic);
 721   sbitmap_vector_free (transp);
 722   sbitmap_vector_free (comp);
 723
 724   if (need_commit)
 725     commit_edge_insertions ();
 726
 727 #if defined (MODE_ENTRY) && defined (MODE_EXIT)
 728   cleanup_cfg (CLEANUP_NO_INSN_DEL);
 729 #else
 730   if (!need_commit && !emited)
 731     return 0;
 732 #endif
 733
 734   return 1;
 735 }
 736
 737 #endif /* OPTIMIZE_MODE_SWITCHING */
 738 \f
 739 static bool
 740 gate_mode_switching (void)
 741 {
 742 #ifdef OPTIMIZE_MODE_SWITCHING
 743   return true;
 744 #else
 745   return false;
 746 #endif
 747 }
 748
 749 static unsigned int
 750 rest_of_handle_mode_switching (void)
 751 {
 752 #ifdef OPTIMIZE_MODE_SWITCHING
 753   optimize_mode_switching ();
 754 #endif /* OPTIMIZE_MODE_SWITCHING */
 755   return 0;
 756 }
 757
 758
 759 struct tree_opt_pass pass_mode_switching =
 760 {
 761   "mode-sw",                            /* name */
 762   gate_mode_switching,                  /* gate */
 763   rest_of_handle_mode_switching,        /* execute */
 764   NULL,                                 /* sub */
 765   NULL,                                 /* next */
 766   0,                                    /* static_pass_number */
 767   TV_MODE_SWITCH,                       /* tv_id */
 768   0,                                    /* properties_required */
 769   0,                                    /* properties_provided */
 770   0,                                    /* properties_destroyed */
 771   0,                                    /* todo_flags_start */
 772   TODO_df_finish | TODO_verify_rtl_sharing |
 773   TODO_dump_func,                       /* todo_flags_finish */
 774   0                                     /* letter */
 775 };