gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   3    2005, 2006, 2007, 2008, 2009, 2010  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 #ifndef GCC_CFGLOOP_H
  22 #define GCC_CFGLOOP_H
  23
  24 #include "basic-block.h"
  25 /* For rtx_code.  */
  26 #include "rtl.h"
  27 #include "vecprim.h"
  28 #include "double-int.h"
  29
  30 #include "bitmap.h"
  31 #include "sbitmap.h"
  32
  33 /* Structure to hold decision about unrolling/peeling.  */
  34 enum lpt_dec
  35 {
  36   LPT_NONE,
  37   LPT_PEEL_COMPLETELY,
  38   LPT_PEEL_SIMPLE,
  39   LPT_UNROLL_CONSTANT,
  40   LPT_UNROLL_RUNTIME,
  41   LPT_UNROLL_STUPID
  42 };
  43
  44 struct GTY (()) lpt_decision {
  45   enum lpt_dec decision;
  46   unsigned times;
  47 };
  48
  49 /* The structure describing a bound on number of iterations of a loop.  */
  50
  51 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  52   /* The statement STMT is executed at most ...  */
  53   gimple stmt;
  54
  55   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  56      The + 1 is added for the following reasons:
  57
  58      a) 0 would otherwise be unused, while we would need to care more about
  59         overflows (as MAX + 1 is sometimes produced as the estimate on number
  60         of executions of STMT).
  61      b) it is consistent with the result of number_of_iterations_exit.  */
  62   double_int bound;
  63
  64   /* True if the statement will cause the loop to be leaved the (at most)
  65      BOUND + 1-st time it is executed, that is, all the statements after it
  66      are executed at most BOUND times.  */
  67   bool is_exit;
  68
  69   /* The next bound in the list.  */
  70   struct nb_iter_bound *next;
  71 };
  72
  73 /* Description of the loop exit.  */
  74
  75 struct GTY (()) loop_exit {
  76   /* The exit edge.  */
  77   struct edge_def *e;
  78
  79   /* Previous and next exit in the list of the exits of the loop.  */
  80   struct loop_exit *prev;
  81   struct loop_exit *next;
  82
  83   /* Next element in the list of loops from that E exits.  */
  84   struct loop_exit *next_e;
  85 };
  86
  87 typedef struct loop *loop_p;
  88 DEF_VEC_P (loop_p);
  89 DEF_VEC_ALLOC_P (loop_p, heap);
  90 DEF_VEC_ALLOC_P (loop_p, gc);
  91
  92 /* An integer estimation of the number of iterations.  Estimate_state
  93    describes what is the state of the estimation.  */
  94 enum loop_estimation
  95 {
  96   /* Estimate was not computed yet.  */
  97   EST_NOT_COMPUTED,
  98   /* Estimate is ready.  */
  99   EST_AVAILABLE
 100 };
 101
 102 /* Structure to hold information for each natural loop.  */
 103 struct GTY ((chain_next ("%h.next"))) loop {
 104   /* Index into loops array.  */
 105   int num;
 106
 107   /* Number of loop insns.  */
 108   unsigned ninsns;
 109
 110   /* Basic block of loop header.  */
 111   struct basic_block_def *header;
 112
 113   /* Basic block of loop latch.  */
 114   struct basic_block_def *latch;
 115
 116   /* For loop unrolling/peeling decision.  */
 117   struct lpt_decision lpt_decision;
 118
 119   /* Average number of executed insns per iteration.  */
 120   unsigned av_ninsns;
 121
 122   /* Number of blocks contained within the loop.  */
 123   unsigned num_nodes;
 124
 125   /* Superloops of the loop, starting with the outermost loop.  */
 126   VEC (loop_p, gc) *superloops;
 127
 128   /* The first inner (child) loop or NULL if innermost loop.  */
 129   struct loop *inner;
 130
 131   /* Link to the next (sibling) loop.  */
 132   struct loop *next;
 133
 134   /* Auxiliary info specific to a pass.  */
 135   PTR GTY ((skip (""))) aux;
 136
 137   /* The number of times the latch of the loop is executed.  This can be an
 138      INTEGER_CST, or a symbolic expression representing the number of
 139      iterations like "N - 1", or a COND_EXPR containing the runtime
 140      conditions under which the number of iterations is non zero.
 141
 142      Don't access this field directly: number_of_latch_executions
 143      computes and caches the computed information in this field.  */
 144   tree nb_iterations;
 145
 146   /* An integer guaranteed to bound the number of iterations of the loop
 147      from above.  */
 148   double_int nb_iterations_upper_bound;
 149
 150   /* An integer giving the expected number of iterations of the loop.  */
 151   double_int nb_iterations_estimate;
 152
 153   bool any_upper_bound;
 154   bool any_estimate;
 155
 156   /* True if the loop can be parallel.  */
 157   bool can_be_parallel;
 158
 159   /* An integer estimation of the number of iterations.  Estimate_state
 160      describes what is the state of the estimation.  */
 161   enum loop_estimation estimate_state;
 162
 163   /* Upper bound on number of iterations of a loop.  */
 164   struct nb_iter_bound *bounds;
 165
 166   /* Head of the cyclic list of the exits of the loop.  */
 167   struct loop_exit *exits;
 168 };
 169
 170 /* Flags for state of loop structure.  */
 171 enum
 172 {
 173   LOOPS_HAVE_PREHEADERS = 1,
 174   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 175   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 176   LOOPS_HAVE_RECORDED_EXITS = 8,
 177   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 178   LOOP_CLOSED_SSA = 32,
 179   LOOPS_NEED_FIXUP = 64,
 180   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 181 };
 182
 183 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 184                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 185 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 186
 187 /* Structure to hold CFG information about natural loops within a function.  */
 188 struct GTY (()) loops {
 189   /* State of loops.  */
 190   int state;
 191
 192   /* Array of the loops.  */
 193   VEC (loop_p, gc) *larray;
 194
 195   /* Maps edges to the list of their descriptions as loop exits.  Edges
 196      whose sources or destinations have loop_father == NULL (which may
 197      happen during the cfg manipulations) should not appear in EXITS.  */
 198   htab_t GTY((param_is (struct loop_exit))) exits;
 199
 200   /* Pointer to root of loop hierarchy tree.  */
 201   struct loop *tree_root;
 202 };
 203
 204 /* Loop recognition.  */
 205 extern int flow_loops_find (struct loops *);
 206 extern void disambiguate_loops_with_multiple_latches (void);
 207 extern void flow_loops_free (struct loops *);
 208 extern void flow_loops_dump (FILE *,
 209                              void (*)(const struct loop *, FILE *, int), int);
 210 extern void flow_loop_dump (const struct loop *, FILE *,
 211                             void (*)(const struct loop *, FILE *, int), int);
 212 struct loop *alloc_loop (void);
 213 extern void flow_loop_free (struct loop *);
 214 int flow_loop_nodes_find (basic_block, struct loop *);
 215 void fix_loop_structure (bitmap changed_bbs);
 216 bool mark_irreducible_loops (void);
 217 void release_recorded_exits (void);
 218 void record_loop_exits (void);
 219 void rescan_loop_exit (edge, bool, bool);
 220
 221 /* Loop data structure manipulation/querying.  */
 222 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 223 extern void flow_loop_tree_node_remove (struct loop *);
 224 extern void add_loop (struct loop *, struct loop *);
 225 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 226 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 227 extern struct loop * find_common_loop (struct loop *, struct loop *);
 228 struct loop *superloop_at_depth (struct loop *, unsigned);
 229 struct eni_weights_d;
 230 extern unsigned tree_num_loop_insns (struct loop *, struct eni_weights_d *);
 231 extern int num_loop_insns (const struct loop *);
 232 extern int average_num_loop_insns (const struct loop *);
 233 extern unsigned get_loop_level (const struct loop *);
 234 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 235 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 236 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 237 extern void mark_loop_exit_edges (void);
 238
 239 /* Loops & cfg manipulation.  */
 240 extern basic_block *get_loop_body (const struct loop *);
 241 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 242                                          unsigned);
 243 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 244 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 245 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 246                                int (*) (const void *, const void *));
 247
 248 extern VEC (edge, heap) *get_loop_exit_edges (const struct loop *);
 249 edge single_exit (const struct loop *);
 250 extern unsigned num_loop_branches (const struct loop *);
 251
 252 extern edge loop_preheader_edge (const struct loop *);
 253 extern edge loop_latch_edge (const struct loop *);
 254
 255 extern void add_bb_to_loop (basic_block, struct loop *);
 256 extern void remove_bb_from_loops (basic_block);
 257
 258 extern void cancel_loop_tree (struct loop *);
 259 extern void delete_loop (struct loop *);
 260
 261 enum
 262 {
 263   CP_SIMPLE_PREHEADERS = 1,
 264   CP_FALLTHRU_PREHEADERS = 2
 265 };
 266
 267 basic_block create_preheader (struct loop *, int);
 268 extern void create_preheaders (int);
 269 extern void force_single_succ_latches (void);
 270
 271 extern void verify_loop_structure (void);
 272
 273 /* Loop analysis.  */
 274 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 275 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 276 extern unsigned expected_loop_iterations (const struct loop *);
 277 extern rtx doloop_condition_get (rtx);
 278
 279 void estimate_numbers_of_iterations_loop (struct loop *, bool);
 280 HOST_WIDE_INT estimated_loop_iterations_int (struct loop *, bool);
 281 bool estimated_loop_iterations (struct loop *, bool, double_int *);
 282
 283 /* Loop manipulation.  */
 284 extern bool can_duplicate_loop_p (const struct loop *loop);
 285
 286 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 287                                            duplicate_loop_to_header_edge.  */
 288 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 289                                            field of newly create BB.  */
 290 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 291                                            a complete peeling.  */
 292
 293 extern edge create_empty_if_region_on_edge (edge, tree);
 294 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 295                                                tree *, tree *, struct loop *);
 296 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 297 extern void duplicate_subloops (struct loop *, struct loop *);
 298 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 299                                            unsigned, sbitmap, edge,
 300                                            VEC (edge, heap) **, int);
 301 extern struct loop *loopify (edge, edge,
 302                              basic_block, edge, edge, bool,
 303                              unsigned, unsigned);
 304 struct loop * loop_version (struct loop *, void *,
 305                             basic_block *, unsigned, unsigned, unsigned, bool);
 306 extern bool remove_path (edge);
 307 void scale_loop_frequencies (struct loop *, int, int);
 308
 309 /* Induction variable analysis.  */
 310
 311 /* The description of induction variable.  The things are a bit complicated
 312    due to need to handle subregs and extends.  The value of the object described
 313    by it can be obtained as follows (all computations are done in extend_mode):
 314
 315    Value in i-th iteration is
 316      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 317
 318    If first_special is true, the value in the first iteration is
 319      delta + mult * base
 320
 321    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 322      subreg_{mode} (base + i * step)
 323
 324    The get_iv_value function can be used to obtain these expressions.
 325
 326    ??? Add a third mode field that would specify the mode in that inner
 327    computation is done, which would enable it to be different from the
 328    outer one?  */
 329
 330 struct rtx_iv
 331 {
 332   /* Its base and step (mode of base and step is supposed to be extend_mode,
 333      see the description above).  */
 334   rtx base, step;
 335
 336   /* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or UNKNOWN).  */
 337   enum rtx_code extend;
 338
 339   /* Operations applied in the extended mode.  */
 340   rtx delta, mult;
 341
 342   /* The mode it is extended to.  */
 343   enum machine_mode extend_mode;
 344
 345   /* The mode the variable iterates in.  */
 346   enum machine_mode mode;
 347
 348   /* Whether the first iteration needs to be handled specially.  */
 349   unsigned first_special : 1;
 350 };
 351
 352 /* The description of an exit from the loop and of the number of iterations
 353    till we take the exit.  */
 354
 355 struct niter_desc
 356 {
 357   /* The edge out of the loop.  */
 358   edge out_edge;
 359
 360   /* The other edge leading from the condition.  */
 361   edge in_edge;
 362
 363   /* True if we are able to say anything about number of iterations of the
 364      loop.  */
 365   bool simple_p;
 366
 367   /* True if the loop iterates the constant number of times.  */
 368   bool const_iter;
 369
 370   /* Number of iterations if constant.  */
 371   unsigned HOST_WIDEST_INT niter;
 372
 373   /* Upper bound on the number of iterations.  */
 374   unsigned HOST_WIDEST_INT niter_max;
 375
 376   /* Assumptions under that the rest of the information is valid.  */
 377   rtx assumptions;
 378
 379   /* Assumptions under that the loop ends before reaching the latch,
 380      even if value of niter_expr says otherwise.  */
 381   rtx noloop_assumptions;
 382
 383   /* Condition under that the loop is infinite.  */
 384   rtx infinite;
 385
 386   /* Whether the comparison is signed.  */
 387   bool signed_p;
 388
 389   /* The mode in that niter_expr should be computed.  */
 390   enum machine_mode mode;
 391
 392   /* The number of iterations of the loop.  */
 393   rtx niter_expr;
 394 };
 395
 396 extern void iv_analysis_loop_init (struct loop *);
 397 extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
 398 extern bool iv_analyze_result (rtx, rtx, struct rtx_iv *);
 399 extern bool iv_analyze_expr (rtx, rtx, enum machine_mode, struct rtx_iv *);
 400 extern rtx get_iv_value (struct rtx_iv *, rtx);
 401 extern bool biv_p (rtx, rtx);
 402 extern void find_simple_exit (struct loop *, struct niter_desc *);
 403 extern void iv_analysis_done (void);
 404
 405 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 406 extern void free_simple_loop_desc (struct loop *loop);
 407
 408 static inline struct niter_desc *
 409 simple_loop_desc (struct loop *loop)
 410 {
 411   return (struct niter_desc *) loop->aux;
 412 }
 413
 414 /* Accessors for the loop structures.  */
 415
 416 /* Returns the loop with index NUM from current_loops.  */
 417
 418 static inline struct loop *
 419 get_loop (unsigned num)
 420 {
 421   return VEC_index (loop_p, current_loops->larray, num);
 422 }
 423
 424 /* Returns the number of superloops of LOOP.  */
 425
 426 static inline unsigned
 427 loop_depth (const struct loop *loop)
 428 {
 429   return VEC_length (loop_p, loop->superloops);
 430 }
 431
 432 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 433    loop.  */
 434
 435 static inline struct loop *
 436 loop_outer (const struct loop *loop)
 437 {
 438   unsigned n = VEC_length (loop_p, loop->superloops);
 439
 440   if (n == 0)
 441     return NULL;
 442
 443   return VEC_index (loop_p, loop->superloops, n - 1);
 444 }
 445
 446 /* Returns true if LOOP has at least one exit edge.  */
 447
 448 static inline bool
 449 loop_has_exit_edges (const struct loop *loop)
 450 {
 451   return loop->exits->next->e != NULL;
 452 }
 453
 454 /* Returns the list of loops in current_loops.  */
 455
 456 static inline VEC (loop_p, gc) *
 457 get_loops (void)
 458 {
 459   if (!current_loops)
 460     return NULL;
 461
 462   return current_loops->larray;
 463 }
 464
 465 /* Returns the number of loops in current_loops (including the removed
 466    ones and the fake loop that forms the root of the loop tree).  */
 467
 468 static inline unsigned
 469 number_of_loops (void)
 470 {
 471   if (!current_loops)
 472     return 0;
 473
 474   return VEC_length (loop_p, current_loops->larray);
 475 }
 476
 477 /* Returns true if state of the loops satisfies all properties
 478    described by FLAGS.  */
 479
 480 static inline bool
 481 loops_state_satisfies_p (unsigned flags)
 482 {
 483   return (current_loops->state & flags) == flags;
 484 }
 485
 486 /* Sets FLAGS to the loops state.  */
 487
 488 static inline void
 489 loops_state_set (unsigned flags)
 490 {
 491   current_loops->state |= flags;
 492 }
 493
 494 /* Clears FLAGS from the loops state.  */
 495
 496 static inline void
 497 loops_state_clear (unsigned flags)
 498 {
 499   if (!current_loops)
 500     return;
 501   current_loops->state &= ~flags;
 502 }
 503
 504 /* Loop iterators.  */
 505
 506 /* Flags for loop iteration.  */
 507
 508 enum li_flags
 509 {
 510   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 511   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 512                                    starting from innermost ones.  */
 513   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 514 };
 515
 516 /* The iterator for loops.  */
 517
 518 typedef struct
 519 {
 520   /* The list of loops to visit.  */
 521   VEC(int,heap) *to_visit;
 522
 523   /* The index of the actual loop.  */
 524   unsigned idx;
 525 } loop_iterator;
 526
 527 static inline void
 528 fel_next (loop_iterator *li, loop_p *loop)
 529 {
 530   int anum;
 531
 532   while (VEC_iterate (int, li->to_visit, li->idx, anum))
 533     {
 534       li->idx++;
 535       *loop = get_loop (anum);
 536       if (*loop)
 537         return;
 538     }
 539
 540   VEC_free (int, heap, li->to_visit);
 541   *loop = NULL;
 542 }
 543
 544 static inline void
 545 fel_init (loop_iterator *li, loop_p *loop, unsigned flags)
 546 {
 547   struct loop *aloop;
 548   unsigned i;
 549   int mn;
 550
 551   li->idx = 0;
 552   if (!current_loops)
 553     {
 554       li->to_visit = NULL;
 555       *loop = NULL;
 556       return;
 557     }
 558
 559   li->to_visit = VEC_alloc (int, heap, number_of_loops ());
 560   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 561
 562   if (flags & LI_ONLY_INNERMOST)
 563     {
 564       for (i = 0; VEC_iterate (loop_p, current_loops->larray, i, aloop); i++)
 565         if (aloop != NULL
 566             && aloop->inner == NULL
 567             && aloop->num >= mn)
 568           VEC_quick_push (int, li->to_visit, aloop->num);
 569     }
 570   else if (flags & LI_FROM_INNERMOST)
 571     {
 572       /* Push the loops to LI->TO_VISIT in postorder.  */
 573       for (aloop = current_loops->tree_root;
 574            aloop->inner != NULL;
 575            aloop = aloop->inner)
 576         continue;
 577
 578       while (1)
 579         {
 580           if (aloop->num >= mn)
 581             VEC_quick_push (int, li->to_visit, aloop->num);
 582
 583           if (aloop->next)
 584             {
 585               for (aloop = aloop->next;
 586                    aloop->inner != NULL;
 587                    aloop = aloop->inner)
 588                 continue;
 589             }
 590           else if (!loop_outer (aloop))
 591             break;
 592           else
 593             aloop = loop_outer (aloop);
 594         }
 595     }
 596   else
 597     {
 598       /* Push the loops to LI->TO_VISIT in preorder.  */
 599       aloop = current_loops->tree_root;
 600       while (1)
 601         {
 602           if (aloop->num >= mn)
 603             VEC_quick_push (int, li->to_visit, aloop->num);
 604
 605           if (aloop->inner != NULL)
 606             aloop = aloop->inner;
 607           else
 608             {
 609               while (aloop != NULL && aloop->next == NULL)
 610                 aloop = loop_outer (aloop);
 611               if (aloop == NULL)
 612                 break;
 613               aloop = aloop->next;
 614             }
 615         }
 616     }
 617
 618   fel_next (li, loop);
 619 }
 620
 621 #define FOR_EACH_LOOP(LI, LOOP, FLAGS) \
 622   for (fel_init (&(LI), &(LOOP), FLAGS); \
 623        (LOOP); \
 624        fel_next (&(LI), &(LOOP)))
 625
 626 #define FOR_EACH_LOOP_BREAK(LI) \
 627   { \
 628     VEC_free (int, heap, (LI)->to_visit); \
 629     break; \
 630   }
 631
 632 /* The properties of the target.  */
 633 struct target_cfgloop {
 634   /* Number of available registers.  */
 635   unsigned x_target_avail_regs;
 636
 637   /* Number of available registers that are call-clobbered.  */
 638   unsigned x_target_clobbered_regs;
 639
 640   /* Number of registers reserved for temporary expressions.  */
 641   unsigned x_target_res_regs;
 642
 643   /* The cost for register when there still is some reserve, but we are
 644      approaching the number of available registers.  */
 645   unsigned x_target_reg_cost[2];
 646
 647   /* The cost for register when we need to spill.  */
 648   unsigned x_target_spill_cost[2];
 649 };
 650
 651 extern struct target_cfgloop default_target_cfgloop;
 652 #if SWITCHABLE_TARGET
 653 extern struct target_cfgloop *this_target_cfgloop;
 654 #else
 655 #define this_target_cfgloop (&default_target_cfgloop)
 656 #endif
 657
 658 #define target_avail_regs \
 659   (this_target_cfgloop->x_target_avail_regs)
 660 #define target_clobbered_regs \
 661   (this_target_cfgloop->x_target_clobbered_regs)
 662 #define target_res_regs \
 663   (this_target_cfgloop->x_target_res_regs)
 664 #define target_reg_cost \
 665   (this_target_cfgloop->x_target_reg_cost)
 666 #define target_spill_cost \
 667   (this_target_cfgloop->x_target_spill_cost)
 668
 669 /* Register pressure estimation for induction variable optimizations & loop
 670    invariant motion.  */
 671 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 672 extern void init_set_costs (void);
 673
 674 /* Loop optimizer initialization.  */
 675 extern void loop_optimizer_init (unsigned);
 676 extern void loop_optimizer_finalize (void);
 677
 678 /* Optimization passes.  */
 679 extern void unswitch_loops (void);
 680
 681 enum
 682 {
 683   UAP_PEEL = 1,         /* Enables loop peeling.  */
 684   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 685   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 686 };
 687
 688 extern void unroll_and_peel_loops (int);
 689 extern void doloop_optimize_loops (void);
 690 extern void move_loop_invariants (void);
 691 extern bool finite_loop_p (struct loop *);
 692
 693 #endif /* GCC_CFGLOOP_H */