gcc/cfgbuild.c

   1 /* Control flow graph building code for GNU compiler.
   2    Copyright (C) 1987-2015 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 \f
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "hash-set.h"
  26 #include "machmode.h"
  27 #include "vec.h"
  28 #include "double-int.h"
  29 #include "input.h"
  30 #include "alias.h"
  31 #include "symtab.h"
  32 #include "wide-int.h"
  33 #include "inchash.h"
  34 #include "tree.h"
  35 #include "rtl.h"
  36 #include "hard-reg-set.h"
  37 #include "predict.h"
  38 #include "hashtab.h"
  39 #include "function.h"
  40 #include "dominance.h"
  41 #include "cfg.h"
  42 #include "cfgrtl.h"
  43 #include "cfganal.h"
  44 #include "cfgbuild.h"
  45 #include "basic-block.h"
  46 #include "regs.h"
  47 #include "flags.h"
  48 #include "except.h"
  49 #include "statistics.h"
  50 #include "real.h"
  51 #include "fixed-value.h"
  52 #include "insn-config.h"
  53 #include "expmed.h"
  54 #include "dojump.h"
  55 #include "explow.h"
  56 #include "calls.h"
  57 #include "emit-rtl.h"
  58 #include "varasm.h"
  59 #include "stmt.h"
  60 #include "expr.h"
  61 #include "diagnostic-core.h"
  62 #include "timevar.h"
  63 #include "sbitmap.h"
  64
  65 static void make_edges (basic_block, basic_block, int);
  66 static void make_label_edge (sbitmap, basic_block, rtx, int);
  67 static void find_bb_boundaries (basic_block);
  68 static void compute_outgoing_frequencies (basic_block);
  69 \f
  70 /* Return true if insn is something that should be contained inside basic
  71    block.  */
  72
  73 bool
  74 inside_basic_block_p (const rtx_insn *insn)
  75 {
  76   switch (GET_CODE (insn))
  77     {
  78     case CODE_LABEL:
  79       /* Avoid creating of basic block for jumptables.  */
  80       return (NEXT_INSN (insn) == 0
  81               || ! JUMP_TABLE_DATA_P (NEXT_INSN (insn)));
  82
  83     case JUMP_INSN:
  84     case CALL_INSN:
  85     case INSN:
  86     case DEBUG_INSN:
  87       return true;
  88
  89     case JUMP_TABLE_DATA:
  90     case BARRIER:
  91     case NOTE:
  92       return false;
  93
  94     default:
  95       gcc_unreachable ();
  96     }
  97 }
  98
  99 /* Return true if INSN may cause control flow transfer, so it should be last in
 100    the basic block.  */
 101
 102 bool
 103 control_flow_insn_p (const rtx_insn *insn)
 104 {
 105   switch (GET_CODE (insn))
 106     {
 107     case NOTE:
 108     case CODE_LABEL:
 109     case DEBUG_INSN:
 110       return false;
 111
 112     case JUMP_INSN:
 113       return true;
 114
 115     case CALL_INSN:
 116       /* Noreturn and sibling call instructions terminate the basic blocks
 117          (but only if they happen unconditionally).  */
 118       if ((SIBLING_CALL_P (insn)
 119            || find_reg_note (insn, REG_NORETURN, 0))
 120           && GET_CODE (PATTERN (insn)) != COND_EXEC)
 121         return true;
 122
 123       /* Call insn may return to the nonlocal goto handler.  */
 124       if (can_nonlocal_goto (insn))
 125         return true;
 126       break;
 127
 128     case INSN:
 129       /* Treat trap instructions like noreturn calls (same provision).  */
 130       if (GET_CODE (PATTERN (insn)) == TRAP_IF
 131           && XEXP (PATTERN (insn), 0) == const1_rtx)
 132         return true;
 133       if (!cfun->can_throw_non_call_exceptions)
 134         return false;
 135       break;
 136
 137     case JUMP_TABLE_DATA:
 138     case BARRIER:
 139       /* It is nonsense to reach this when looking for the
 140          end of basic block, but before dead code is eliminated
 141          this may happen.  */
 142       return false;
 143
 144     default:
 145       gcc_unreachable ();
 146     }
 147
 148   return can_throw_internal (insn);
 149 }
 150
 151 \f
 152 /* Create an edge between two basic blocks.  FLAGS are auxiliary information
 153    about the edge that is accumulated between calls.  */
 154
 155 /* Create an edge from a basic block to a label.  */
 156
 157 static void
 158 make_label_edge (sbitmap edge_cache, basic_block src, rtx label, int flags)
 159 {
 160   gcc_assert (LABEL_P (label));
 161
 162   /* If the label was never emitted, this insn is junk, but avoid a
 163      crash trying to refer to BLOCK_FOR_INSN (label).  This can happen
 164      as a result of a syntax error and a diagnostic has already been
 165      printed.  */
 166
 167   if (INSN_UID (label) == 0)
 168     return;
 169
 170   cached_make_edge (edge_cache, src, BLOCK_FOR_INSN (label), flags);
 171 }
 172
 173 /* Create the edges generated by INSN in REGION.  */
 174
 175 void
 176 rtl_make_eh_edge (sbitmap edge_cache, basic_block src, rtx insn)
 177 {
 178   eh_landing_pad lp = get_eh_landing_pad_from_rtx (insn);
 179
 180   if (lp)
 181     {
 182       rtx label = lp->landing_pad;
 183
 184       /* During initial rtl generation, use the post_landing_pad.  */
 185       if (label == NULL)
 186         {
 187           gcc_assert (lp->post_landing_pad);
 188           label = label_rtx (lp->post_landing_pad);
 189         }
 190
 191       make_label_edge (edge_cache, src, label,
 192                        EDGE_ABNORMAL | EDGE_EH
 193                        | (CALL_P (insn) ? EDGE_ABNORMAL_CALL : 0));
 194     }
 195 }
 196
 197 /* States of basic block as seen by find_many_sub_basic_blocks.  */
 198 enum state {
 199   /* Basic blocks created via split_block belong to this state.
 200      make_edges will examine these basic blocks to see if we need to
 201      create edges going out of them.  */
 202   BLOCK_NEW = 0,
 203
 204   /* Basic blocks that do not need examining belong to this state.
 205      These blocks will be left intact.  In particular, make_edges will
 206      not create edges going out of these basic blocks.  */
 207   BLOCK_ORIGINAL,
 208
 209   /* Basic blocks that may need splitting (due to a label appearing in
 210      the middle, etc) belong to this state.  After splitting them,
 211      make_edges will create edges going out of them as needed.  */
 212   BLOCK_TO_SPLIT
 213 };
 214
 215 #define STATE(BB) (enum state) ((size_t) (BB)->aux)
 216 #define SET_STATE(BB, STATE) ((BB)->aux = (void *) (size_t) (STATE))
 217
 218 /* Used internally by purge_dead_tablejump_edges, ORed into state.  */
 219 #define BLOCK_USED_BY_TABLEJUMP         32
 220 #define FULL_STATE(BB) ((size_t) (BB)->aux)
 221
 222 /* Identify the edges going out of basic blocks between MIN and MAX,
 223    inclusive, that have their states set to BLOCK_NEW or
 224    BLOCK_TO_SPLIT.
 225
 226    UPDATE_P should be nonzero if we are updating CFG and zero if we
 227    are building CFG from scratch.  */
 228
 229 static void
 230 make_edges (basic_block min, basic_block max, int update_p)
 231 {
 232   basic_block bb;
 233   sbitmap edge_cache = NULL;
 234
 235   /* Heavy use of computed goto in machine-generated code can lead to
 236      nearly fully-connected CFGs.  In that case we spend a significant
 237      amount of time searching the edge lists for duplicates.  */
 238   if (forced_labels || cfun->cfg->max_jumptable_ents > 100)
 239     edge_cache = sbitmap_alloc (last_basic_block_for_fn (cfun));
 240
 241   /* By nature of the way these get numbered, ENTRY_BLOCK_PTR->next_bb block
 242      is always the entry.  */
 243   if (min == ENTRY_BLOCK_PTR_FOR_FN (cfun)->next_bb)
 244     make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), min, EDGE_FALLTHRU);
 245
 246   FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
 247     {
 248       rtx_insn *insn;
 249       enum rtx_code code;
 250       edge e;
 251       edge_iterator ei;
 252
 253       if (STATE (bb) == BLOCK_ORIGINAL)
 254         continue;
 255
 256       /* If we have an edge cache, cache edges going out of BB.  */
 257       if (edge_cache)
 258         {
 259           bitmap_clear (edge_cache);
 260           if (update_p)
 261             {
 262               FOR_EACH_EDGE (e, ei, bb->succs)
 263                 if (e->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
 264                   bitmap_set_bit (edge_cache, e->dest->index);
 265             }
 266         }
 267
 268       if (LABEL_P (BB_HEAD (bb))
 269           && LABEL_ALT_ENTRY_P (BB_HEAD (bb)))
 270         cached_make_edge (NULL, ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
 271
 272       /* Examine the last instruction of the block, and discover the
 273          ways we can leave the block.  */
 274
 275       insn = BB_END (bb);
 276       code = GET_CODE (insn);
 277
 278       /* A branch.  */
 279       if (code == JUMP_INSN)
 280         {
 281           rtx tmp;
 282           rtx_jump_table_data *table;
 283
 284           /* Recognize a non-local goto as a branch outside the
 285              current function.  */
 286           if (find_reg_note (insn, REG_NON_LOCAL_GOTO, NULL_RTX))
 287             ;
 288
 289           /* Recognize a tablejump and do the right thing.  */
 290           else if (tablejump_p (insn, NULL, &table))
 291             {
 292               rtvec vec = table->get_labels ();
 293               int j;
 294
 295               for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
 296                 make_label_edge (edge_cache, bb,
 297                                  XEXP (RTVEC_ELT (vec, j), 0), 0);
 298
 299               /* Some targets (eg, ARM) emit a conditional jump that also
 300                  contains the out-of-range target.  Scan for these and
 301                  add an edge if necessary.  */
 302               if ((tmp = single_set (insn)) != NULL
 303                   && SET_DEST (tmp) == pc_rtx
 304                   && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
 305                   && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
 306                 make_label_edge (edge_cache, bb,
 307                                  LABEL_REF_LABEL (XEXP (SET_SRC (tmp), 2)), 0);
 308             }
 309
 310           /* If this is a computed jump, then mark it as reaching
 311              everything on the forced_labels list.  */
 312           else if (computed_jump_p (insn))
 313             {
 314               for (rtx_insn_list *x = forced_labels; x; x = x->next ())
 315                 make_label_edge (edge_cache, bb, x->insn (), EDGE_ABNORMAL);
 316             }
 317
 318           /* Returns create an exit out.  */
 319           else if (returnjump_p (insn))
 320             cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun), 0);
 321
 322           /* Recognize asm goto and do the right thing.  */
 323           else if ((tmp = extract_asm_operands (PATTERN (insn))) != NULL)
 324             {
 325               int i, n = ASM_OPERANDS_LABEL_LENGTH (tmp);
 326               for (i = 0; i < n; ++i)
 327                 make_label_edge (edge_cache, bb,
 328                                  XEXP (ASM_OPERANDS_LABEL (tmp, i), 0), 0);
 329             }
 330
 331           /* Otherwise, we have a plain conditional or unconditional jump.  */
 332           else
 333             {
 334               gcc_assert (JUMP_LABEL (insn));
 335               make_label_edge (edge_cache, bb, JUMP_LABEL (insn), 0);
 336             }
 337         }
 338
 339       /* If this is a sibling call insn, then this is in effect a combined call
 340          and return, and so we need an edge to the exit block.  No need to
 341          worry about EH edges, since we wouldn't have created the sibling call
 342          in the first place.  */
 343       if (code == CALL_INSN && SIBLING_CALL_P (insn))
 344         cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
 345                           EDGE_SIBCALL | EDGE_ABNORMAL);
 346
 347       /* If this is a CALL_INSN, then mark it as reaching the active EH
 348          handler for this CALL_INSN.  If we're handling non-call
 349          exceptions then any insn can reach any of the active handlers.
 350          Also mark the CALL_INSN as reaching any nonlocal goto handler.  */
 351       else if (code == CALL_INSN || cfun->can_throw_non_call_exceptions)
 352         {
 353           /* Add any appropriate EH edges.  */
 354           rtl_make_eh_edge (edge_cache, bb, insn);
 355
 356           if (code == CALL_INSN)
 357             {
 358               if (can_nonlocal_goto (insn))
 359                 {
 360                   /* ??? This could be made smarter: in some cases it's
 361                      possible to tell that certain calls will not do a
 362                      nonlocal goto.  For example, if the nested functions
 363                      that do the nonlocal gotos do not have their addresses
 364                      taken, then only calls to those functions or to other
 365                      nested functions that use them could possibly do
 366                      nonlocal gotos.  */
 367                   for (rtx_insn_list *x = nonlocal_goto_handler_labels;
 368                        x;
 369                        x = x->next ())
 370                     make_label_edge (edge_cache, bb, x->insn (),
 371                                      EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
 372                 }
 373
 374               if (flag_tm)
 375                 {
 376                   rtx note;
 377                   for (note = REG_NOTES (insn); note; note = XEXP (note, 1))
 378                     if (REG_NOTE_KIND (note) == REG_TM)
 379                       make_label_edge (edge_cache, bb, XEXP (note, 0),
 380                                        EDGE_ABNORMAL | EDGE_ABNORMAL_CALL);
 381                 }
 382             }
 383         }
 384
 385       /* Find out if we can drop through to the next block.  */
 386       insn = NEXT_INSN (insn);
 387       e = find_edge (bb, EXIT_BLOCK_PTR_FOR_FN (cfun));
 388       if (e && e->flags & EDGE_FALLTHRU)
 389         insn = NULL;
 390
 391       while (insn
 392              && NOTE_P (insn)
 393              && NOTE_KIND (insn) != NOTE_INSN_BASIC_BLOCK)
 394         insn = NEXT_INSN (insn);
 395
 396       if (!insn)
 397         cached_make_edge (edge_cache, bb, EXIT_BLOCK_PTR_FOR_FN (cfun),
 398                           EDGE_FALLTHRU);
 399       else if (bb->next_bb != EXIT_BLOCK_PTR_FOR_FN (cfun))
 400         {
 401           if (insn == BB_HEAD (bb->next_bb))
 402             cached_make_edge (edge_cache, bb, bb->next_bb, EDGE_FALLTHRU);
 403         }
 404     }
 405
 406   if (edge_cache)
 407     sbitmap_free (edge_cache);
 408 }
 409 \f
 410 static void
 411 mark_tablejump_edge (rtx label)
 412 {
 413   basic_block bb;
 414
 415   gcc_assert (LABEL_P (label));
 416   /* See comment in make_label_edge.  */
 417   if (INSN_UID (label) == 0)
 418     return;
 419   bb = BLOCK_FOR_INSN (label);
 420   SET_STATE (bb, FULL_STATE (bb) | BLOCK_USED_BY_TABLEJUMP);
 421 }
 422
 423 static void
 424 purge_dead_tablejump_edges (basic_block bb, rtx_jump_table_data *table)
 425 {
 426   rtx_insn *insn = BB_END (bb);
 427   rtx tmp;
 428   rtvec vec;
 429   int j;
 430   edge_iterator ei;
 431   edge e;
 432
 433   vec = table->get_labels ();
 434
 435   for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
 436     mark_tablejump_edge (XEXP (RTVEC_ELT (vec, j), 0));
 437
 438   /* Some targets (eg, ARM) emit a conditional jump that also
 439      contains the out-of-range target.  Scan for these and
 440      add an edge if necessary.  */
 441   if ((tmp = single_set (insn)) != NULL
 442        && SET_DEST (tmp) == pc_rtx
 443        && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
 444        && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF)
 445     mark_tablejump_edge (LABEL_REF_LABEL (XEXP (SET_SRC (tmp), 2)));
 446
 447   for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
 448     {
 449       if (FULL_STATE (e->dest) & BLOCK_USED_BY_TABLEJUMP)
 450         SET_STATE (e->dest, FULL_STATE (e->dest)
 451                             & ~(size_t) BLOCK_USED_BY_TABLEJUMP);
 452       else if (!(e->flags & (EDGE_ABNORMAL | EDGE_EH)))
 453         {
 454           remove_edge (e);
 455           continue;
 456         }
 457       ei_next (&ei);
 458     }
 459 }
 460
 461 /* Scan basic block BB for possible BB boundaries inside the block
 462    and create new basic blocks in the progress.  */
 463
 464 static void
 465 find_bb_boundaries (basic_block bb)
 466 {
 467   basic_block orig_bb = bb;
 468   rtx_insn *insn = BB_HEAD (bb);
 469   rtx_insn *end = BB_END (bb), *x;
 470   rtx_jump_table_data *table;
 471   rtx_insn *flow_transfer_insn = NULL;
 472   edge fallthru = NULL;
 473
 474   if (insn == BB_END (bb))
 475     return;
 476
 477   if (LABEL_P (insn))
 478     insn = NEXT_INSN (insn);
 479
 480   /* Scan insn chain and try to find new basic block boundaries.  */
 481   while (1)
 482     {
 483       enum rtx_code code = GET_CODE (insn);
 484
 485       /* In case we've previously seen an insn that effects a control
 486          flow transfer, split the block.  */
 487       if ((flow_transfer_insn || code == CODE_LABEL)
 488           && inside_basic_block_p (insn))
 489         {
 490           fallthru = split_block (bb, PREV_INSN (insn));
 491           if (flow_transfer_insn)
 492             {
 493               BB_END (bb) = flow_transfer_insn;
 494
 495               /* Clean up the bb field for the insns between the blocks.  */
 496               for (x = NEXT_INSN (flow_transfer_insn);
 497                    x != BB_HEAD (fallthru->dest);
 498                    x = NEXT_INSN (x))
 499                 if (!BARRIER_P (x))
 500                   set_block_for_insn (x, NULL);
 501             }
 502
 503           bb = fallthru->dest;
 504           remove_edge (fallthru);
 505           flow_transfer_insn = NULL;
 506           if (code == CODE_LABEL && LABEL_ALT_ENTRY_P (insn))
 507             make_edge (ENTRY_BLOCK_PTR_FOR_FN (cfun), bb, 0);
 508         }
 509       else if (code == BARRIER)
 510         {
 511           /* __builtin_unreachable () may cause a barrier to be emitted in
 512              the middle of a BB.  We need to split it in the same manner as
 513              if the barrier were preceded by a control_flow_insn_p insn.  */
 514           if (!flow_transfer_insn)
 515             flow_transfer_insn = prev_nonnote_insn_bb (insn);
 516         }
 517
 518       if (control_flow_insn_p (insn))
 519         flow_transfer_insn = insn;
 520       if (insn == end)
 521         break;
 522       insn = NEXT_INSN (insn);
 523     }
 524
 525   /* In case expander replaced normal insn by sequence terminating by
 526      return and barrier, or possibly other sequence not behaving like
 527      ordinary jump, we need to take care and move basic block boundary.  */
 528   if (flow_transfer_insn)
 529     {
 530       BB_END (bb) = flow_transfer_insn;
 531
 532       /* Clean up the bb field for the insns that do not belong to BB.  */
 533       x = flow_transfer_insn;
 534       while (x != end)
 535         {
 536           x = NEXT_INSN (x);
 537           if (!BARRIER_P (x))
 538             set_block_for_insn (x, NULL);
 539         }
 540     }
 541
 542   /* We've possibly replaced the conditional jump by conditional jump
 543      followed by cleanup at fallthru edge, so the outgoing edges may
 544      be dead.  */
 545   purge_dead_edges (bb);
 546
 547   /* purge_dead_edges doesn't handle tablejump's, but if we have split the
 548      basic block, we might need to kill some edges.  */
 549   if (bb != orig_bb && tablejump_p (BB_END (bb), NULL, &table))
 550     purge_dead_tablejump_edges (bb, table);
 551 }
 552
 553 /*  Assume that frequency of basic block B is known.  Compute frequencies
 554     and probabilities of outgoing edges.  */
 555
 556 static void
 557 compute_outgoing_frequencies (basic_block b)
 558 {
 559   edge e, f;
 560   edge_iterator ei;
 561
 562   if (EDGE_COUNT (b->succs) == 2)
 563     {
 564       rtx note = find_reg_note (BB_END (b), REG_BR_PROB, NULL);
 565       int probability;
 566
 567       if (note)
 568         {
 569           probability = XINT (note, 0);
 570           e = BRANCH_EDGE (b);
 571           e->probability = probability;
 572           e->count = apply_probability (b->count, probability);
 573           f = FALLTHRU_EDGE (b);
 574           f->probability = REG_BR_PROB_BASE - probability;
 575           f->count = b->count - e->count;
 576           return;
 577         }
 578       else
 579         {
 580           guess_outgoing_edge_probabilities (b);
 581         }
 582     }
 583   else if (single_succ_p (b))
 584     {
 585       e = single_succ_edge (b);
 586       e->probability = REG_BR_PROB_BASE;
 587       e->count = b->count;
 588       return;
 589     }
 590   else
 591     {
 592       /* We rely on BBs with more than two successors to have sane probabilities
 593          and do not guess them here. For BBs terminated by switch statements
 594          expanded to jump-table jump, we have done the right thing during
 595          expansion. For EH edges, we still guess the probabilities here.  */
 596       bool complex_edge = false;
 597       FOR_EACH_EDGE (e, ei, b->succs)
 598         if (e->flags & EDGE_COMPLEX)
 599           {
 600             complex_edge = true;
 601             break;
 602           }
 603       if (complex_edge)
 604         guess_outgoing_edge_probabilities (b);
 605     }
 606
 607   if (b->count)
 608     FOR_EACH_EDGE (e, ei, b->succs)
 609       e->count = apply_probability (b->count, e->probability);
 610 }
 611
 612 /* Assume that some pass has inserted labels or control flow
 613    instructions within a basic block.  Split basic blocks as needed
 614    and create edges.  */
 615
 616 void
 617 find_many_sub_basic_blocks (sbitmap blocks)
 618 {
 619   basic_block bb, min, max;
 620
 621   FOR_EACH_BB_FN (bb, cfun)
 622     SET_STATE (bb,
 623                bitmap_bit_p (blocks, bb->index) ? BLOCK_TO_SPLIT : BLOCK_ORIGINAL);
 624
 625   FOR_EACH_BB_FN (bb, cfun)
 626     if (STATE (bb) == BLOCK_TO_SPLIT)
 627       find_bb_boundaries (bb);
 628
 629   FOR_EACH_BB_FN (bb, cfun)
 630     if (STATE (bb) != BLOCK_ORIGINAL)
 631       break;
 632
 633   min = max = bb;
 634   for (; bb != EXIT_BLOCK_PTR_FOR_FN (cfun); bb = bb->next_bb)
 635     if (STATE (bb) != BLOCK_ORIGINAL)
 636       max = bb;
 637
 638   /* Now re-scan and wire in all edges.  This expect simple (conditional)
 639      jumps at the end of each new basic blocks.  */
 640   make_edges (min, max, 1);
 641
 642   /* Update branch probabilities.  Expect only (un)conditional jumps
 643      to be created with only the forward edges.  */
 644   if (profile_status_for_fn (cfun) != PROFILE_ABSENT)
 645     FOR_BB_BETWEEN (bb, min, max->next_bb, next_bb)
 646       {
 647         edge e;
 648         edge_iterator ei;
 649
 650         if (STATE (bb) == BLOCK_ORIGINAL)
 651           continue;
 652         if (STATE (bb) == BLOCK_NEW)
 653           {
 654             bb->count = 0;
 655             bb->frequency = 0;
 656             FOR_EACH_EDGE (e, ei, bb->preds)
 657               {
 658                 bb->count += e->count;
 659                 bb->frequency += EDGE_FREQUENCY (e);
 660               }
 661           }
 662
 663         compute_outgoing_frequencies (bb);
 664       }
 665
 666   FOR_EACH_BB_FN (bb, cfun)
 667     SET_STATE (bb, 0);
 668 }