gcc/cfgloop.h

   1 /* Natural loop functions
   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 #ifndef GCC_CFGLOOP_H
  21 #define GCC_CFGLOOP_H
  22
  23 #include "cfgloopmanip.h"
  24
  25 /* Structure to hold decision about unrolling/peeling.  */
  26 enum lpt_dec
  27 {
  28   LPT_NONE,
  29   LPT_UNROLL_CONSTANT,
  30   LPT_UNROLL_RUNTIME,
  31   LPT_UNROLL_STUPID
  32 };
  33
  34 struct GTY (()) lpt_decision {
  35   enum lpt_dec decision;
  36   unsigned times;
  37 };
  38
  39 /* The type of extend applied to an IV.  */
  40 enum iv_extend_code
  41 {
  42   IV_SIGN_EXTEND,
  43   IV_ZERO_EXTEND,
  44   IV_UNKNOWN_EXTEND
  45 };
  46
  47 /* The structure describing a bound on number of iterations of a loop.  */
  48
  49 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  50   /* The statement STMT is executed at most ...  */
  51   gimple stmt;
  52
  53   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  54      The + 1 is added for the following reasons:
  55
  56      a) 0 would otherwise be unused, while we would need to care more about
  57         overflows (as MAX + 1 is sometimes produced as the estimate on number
  58         of executions of STMT).
  59      b) it is consistent with the result of number_of_iterations_exit.  */
  60   widest_int bound;
  61
  62   /* True if the statement will cause the loop to be leaved the (at most)
  63      BOUND + 1-st time it is executed, that is, all the statements after it
  64      are executed at most BOUND times.  */
  65   bool is_exit;
  66
  67   /* The next bound in the list.  */
  68   struct nb_iter_bound *next;
  69 };
  70
  71 /* Description of the loop exit.  */
  72
  73 struct GTY ((for_user)) loop_exit {
  74   /* The exit edge.  */
  75   edge e;
  76
  77   /* Previous and next exit in the list of the exits of the loop.  */
  78   struct loop_exit *prev;
  79   struct loop_exit *next;
  80
  81   /* Next element in the list of loops from that E exits.  */
  82   struct loop_exit *next_e;
  83 };
  84
  85 struct loop_exit_hasher : ggc_ptr_hash<loop_exit>
  86 {
  87   typedef edge compare_type;
  88
  89   static hashval_t hash (loop_exit *);
  90   static bool equal (loop_exit *, edge);
  91   static void remove (loop_exit *);
  92 };
  93
  94 typedef struct loop *loop_p;
  95
  96 /* An integer estimation of the number of iterations.  Estimate_state
  97    describes what is the state of the estimation.  */
  98 enum loop_estimation
  99 {
 100   /* Estimate was not computed yet.  */
 101   EST_NOT_COMPUTED,
 102   /* Estimate is ready.  */
 103   EST_AVAILABLE,
 104   EST_LAST
 105 };
 106
 107 /* The structure describing non-overflow control induction variable for
 108    loop's exit edge.  */
 109 struct GTY ((chain_next ("%h.next"))) control_iv {
 110   tree base;
 111   tree step;
 112   struct control_iv *next;
 113 };
 114
 115 /* Structure to hold information for each natural loop.  */
 116 struct GTY ((chain_next ("%h.next"))) loop {
 117   /* Index into loops array.  */
 118   int num;
 119
 120   /* Number of loop insns.  */
 121   unsigned ninsns;
 122
 123   /* Basic block of loop header.  */
 124   basic_block header;
 125
 126   /* Basic block of loop latch.  */
 127   basic_block latch;
 128
 129   /* For loop unrolling/peeling decision.  */
 130   struct lpt_decision lpt_decision;
 131
 132   /* Average number of executed insns per iteration.  */
 133   unsigned av_ninsns;
 134
 135   /* Number of blocks contained within the loop.  */
 136   unsigned num_nodes;
 137
 138   /* Superloops of the loop, starting with the outermost loop.  */
 139   vec<loop_p, va_gc> *superloops;
 140
 141   /* The first inner (child) loop or NULL if innermost loop.  */
 142   struct loop *inner;
 143
 144   /* Link to the next (sibling) loop.  */
 145   struct loop *next;
 146
 147   /* Auxiliary info specific to a pass.  */
 148   PTR GTY ((skip (""))) aux;
 149
 150   /* The number of times the latch of the loop is executed.  This can be an
 151      INTEGER_CST, or a symbolic expression representing the number of
 152      iterations like "N - 1", or a COND_EXPR containing the runtime
 153      conditions under which the number of iterations is non zero.
 154
 155      Don't access this field directly: number_of_latch_executions
 156      computes and caches the computed information in this field.  */
 157   tree nb_iterations;
 158
 159   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 160      valid if any_upper_bound is true.  */
 161   widest_int nb_iterations_upper_bound;
 162
 163   /* An integer giving an estimate on nb_iterations.  Unlike
 164      nb_iterations_upper_bound, there is no guarantee that it is at least
 165      nb_iterations.  */
 166   widest_int nb_iterations_estimate;
 167
 168   bool any_upper_bound;
 169   bool any_estimate;
 170
 171   /* True if the loop can be parallel.  */
 172   bool can_be_parallel;
 173
 174   /* True if -Waggressive-loop-optimizations warned about this loop
 175      already.  */
 176   bool warned_aggressive_loop_optimizations;
 177
 178   /* An integer estimation of the number of iterations.  Estimate_state
 179      describes what is the state of the estimation.  */
 180   enum loop_estimation estimate_state;
 181
 182   /* If > 0, an integer, where the user asserted that for any
 183      I in [ 0, nb_iterations ) and for any J in
 184      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 185      of the loop can be safely evaluated concurrently.  */
 186   int safelen;
 187
 188   /* True if this loop should never be vectorized.  */
 189   bool dont_vectorize;
 190
 191   /* True if we should try harder to vectorize this loop.  */
 192   bool force_vectorize;
 193
 194   /* For SIMD loops, this is a unique identifier of the loop, referenced
 195      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 196      builtins.  */
 197   tree simduid;
 198
 199   /* Upper bound on number of iterations of a loop.  */
 200   struct nb_iter_bound *bounds;
 201
 202   /* Non-overflow control ivs of a loop.  */
 203   struct control_iv *control_ivs;
 204
 205   /* Head of the cyclic list of the exits of the loop.  */
 206   struct loop_exit *exits;
 207
 208   /* Number of iteration analysis data for RTL.  */
 209   struct niter_desc *simple_loop_desc;
 210
 211   /* For sanity checking during loop fixup we record here the former
 212      loop header for loops marked for removal.  Note that this prevents
 213      the basic-block from being collected but its index can still be
 214      reused.  */
 215   basic_block former_header;
 216 };
 217
 218 /* Flags for state of loop structure.  */
 219 enum
 220 {
 221   LOOPS_HAVE_PREHEADERS = 1,
 222   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 223   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 224   LOOPS_HAVE_RECORDED_EXITS = 8,
 225   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 226   LOOP_CLOSED_SSA = 32,
 227   LOOPS_NEED_FIXUP = 64,
 228   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 229 };
 230
 231 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 232                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 233 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 234
 235 /* Structure to hold CFG information about natural loops within a function.  */
 236 struct GTY (()) loops {
 237   /* State of loops.  */
 238   int state;
 239
 240   /* Array of the loops.  */
 241   vec<loop_p, va_gc> *larray;
 242
 243   /* Maps edges to the list of their descriptions as loop exits.  Edges
 244      whose sources or destinations have loop_father == NULL (which may
 245      happen during the cfg manipulations) should not appear in EXITS.  */
 246   hash_table<loop_exit_hasher> *GTY(()) exits;
 247
 248   /* Pointer to root of loop hierarchy tree.  */
 249   struct loop *tree_root;
 250 };
 251
 252 /* Loop recognition.  */
 253 bool bb_loop_header_p (basic_block);
 254 void init_loops_structure (struct function *, struct loops *, unsigned);
 255 extern struct loops *flow_loops_find (struct loops *);
 256 extern void disambiguate_loops_with_multiple_latches (void);
 257 extern void flow_loops_free (struct loops *);
 258 extern void flow_loops_dump (FILE *,
 259                              void (*)(const struct loop *, FILE *, int), int);
 260 extern void flow_loop_dump (const struct loop *, FILE *,
 261                             void (*)(const struct loop *, FILE *, int), int);
 262 struct loop *alloc_loop (void);
 263 extern void flow_loop_free (struct loop *);
 264 int flow_loop_nodes_find (basic_block, struct loop *);
 265 unsigned fix_loop_structure (bitmap changed_bbs);
 266 bool mark_irreducible_loops (void);
 267 void release_recorded_exits (void);
 268 void record_loop_exits (void);
 269 void rescan_loop_exit (edge, bool, bool);
 270
 271 /* Loop data structure manipulation/querying.  */
 272 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 273 extern void flow_loop_tree_node_remove (struct loop *);
 274 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 275 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 276 extern struct loop * find_common_loop (struct loop *, struct loop *);
 277 struct loop *superloop_at_depth (struct loop *, unsigned);
 278 struct eni_weights;
 279 extern int num_loop_insns (const struct loop *);
 280 extern int average_num_loop_insns (const struct loop *);
 281 extern unsigned get_loop_level (const struct loop *);
 282 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 283 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 284 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 285 extern void mark_loop_exit_edges (void);
 286 extern location_t get_loop_location (struct loop *loop);
 287
 288 /* Loops & cfg manipulation.  */
 289 extern basic_block *get_loop_body (const struct loop *);
 290 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 291                                          unsigned);
 292 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 293 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 294 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 295                                int (*) (const void *, const void *));
 296
 297 extern vec<edge> get_loop_exit_edges (const struct loop *);
 298 extern edge single_exit (const struct loop *);
 299 extern edge single_likely_exit (struct loop *loop);
 300 extern unsigned num_loop_branches (const struct loop *);
 301
 302 extern edge loop_preheader_edge (const struct loop *);
 303 extern edge loop_latch_edge (const struct loop *);
 304
 305 extern void add_bb_to_loop (basic_block, struct loop *);
 306 extern void remove_bb_from_loops (basic_block);
 307
 308 extern void cancel_loop_tree (struct loop *);
 309 extern void delete_loop (struct loop *);
 310
 311
 312 extern void verify_loop_structure (void);
 313
 314 /* Loop analysis.  */
 315 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 316 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 317 extern unsigned expected_loop_iterations (const struct loop *);
 318 extern rtx doloop_condition_get (rtx);
 319
 320 void mark_loop_for_removal (loop_p);
 321
 322 /* Induction variable analysis.  */
 323
 324 /* The description of induction variable.  The things are a bit complicated
 325    due to need to handle subregs and extends.  The value of the object described
 326    by it can be obtained as follows (all computations are done in extend_mode):
 327
 328    Value in i-th iteration is
 329      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 330
 331    If first_special is true, the value in the first iteration is
 332      delta + mult * base
 333
 334    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 335      subreg_{mode} (base + i * step)
 336
 337    The get_iv_value function can be used to obtain these expressions.
 338
 339    ??? Add a third mode field that would specify the mode in that inner
 340    computation is done, which would enable it to be different from the
 341    outer one?  */
 342
 343 struct rtx_iv
 344 {
 345   /* Its base and step (mode of base and step is supposed to be extend_mode,
 346      see the description above).  */
 347   rtx base, step;
 348
 349   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 350      or IV_UNKNOWN_EXTEND).  */
 351   enum iv_extend_code extend;
 352
 353   /* Operations applied in the extended mode.  */
 354   rtx delta, mult;
 355
 356   /* The mode it is extended to.  */
 357   machine_mode extend_mode;
 358
 359   /* The mode the variable iterates in.  */
 360   machine_mode mode;
 361
 362   /* Whether the first iteration needs to be handled specially.  */
 363   unsigned first_special : 1;
 364 };
 365
 366 /* The description of an exit from the loop and of the number of iterations
 367    till we take the exit.  */
 368
 369 struct GTY(()) niter_desc
 370 {
 371   /* The edge out of the loop.  */
 372   edge out_edge;
 373
 374   /* The other edge leading from the condition.  */
 375   edge in_edge;
 376
 377   /* True if we are able to say anything about number of iterations of the
 378      loop.  */
 379   bool simple_p;
 380
 381   /* True if the loop iterates the constant number of times.  */
 382   bool const_iter;
 383
 384   /* Number of iterations if constant.  */
 385   uint64_t niter;
 386
 387   /* Assumptions under that the rest of the information is valid.  */
 388   rtx assumptions;
 389
 390   /* Assumptions under that the loop ends before reaching the latch,
 391      even if value of niter_expr says otherwise.  */
 392   rtx noloop_assumptions;
 393
 394   /* Condition under that the loop is infinite.  */
 395   rtx infinite;
 396
 397   /* Whether the comparison is signed.  */
 398   bool signed_p;
 399
 400   /* The mode in that niter_expr should be computed.  */
 401   machine_mode mode;
 402
 403   /* The number of iterations of the loop.  */
 404   rtx niter_expr;
 405 };
 406
 407 extern void iv_analysis_loop_init (struct loop *);
 408 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 409 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 410 extern bool iv_analyze_expr (rtx_insn *, rtx, machine_mode,
 411                              struct rtx_iv *);
 412 extern rtx get_iv_value (struct rtx_iv *, rtx);
 413 extern bool biv_p (rtx_insn *, rtx);
 414 extern void find_simple_exit (struct loop *, struct niter_desc *);
 415 extern void iv_analysis_done (void);
 416
 417 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 418 extern void free_simple_loop_desc (struct loop *loop);
 419
 420 static inline struct niter_desc *
 421 simple_loop_desc (struct loop *loop)
 422 {
 423   return loop->simple_loop_desc;
 424 }
 425
 426 /* Accessors for the loop structures.  */
 427
 428 /* Returns the loop with index NUM from FNs loop tree.  */
 429
 430 static inline struct loop *
 431 get_loop (struct function *fn, unsigned num)
 432 {
 433   return (*loops_for_fn (fn)->larray)[num];
 434 }
 435
 436 /* Returns the number of superloops of LOOP.  */
 437
 438 static inline unsigned
 439 loop_depth (const struct loop *loop)
 440 {
 441   return vec_safe_length (loop->superloops);
 442 }
 443
 444 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 445    loop.  */
 446
 447 static inline struct loop *
 448 loop_outer (const struct loop *loop)
 449 {
 450   unsigned n = vec_safe_length (loop->superloops);
 451
 452   if (n == 0)
 453     return NULL;
 454
 455   return (*loop->superloops)[n - 1];
 456 }
 457
 458 /* Returns true if LOOP has at least one exit edge.  */
 459
 460 static inline bool
 461 loop_has_exit_edges (const struct loop *loop)
 462 {
 463   return loop->exits->next->e != NULL;
 464 }
 465
 466 /* Returns the list of loops in FN.  */
 467
 468 inline vec<loop_p, va_gc> *
 469 get_loops (struct function *fn)
 470 {
 471   struct loops *loops = loops_for_fn (fn);
 472   if (!loops)
 473     return NULL;
 474
 475   return loops->larray;
 476 }
 477
 478 /* Returns the number of loops in FN (including the removed
 479    ones and the fake loop that forms the root of the loop tree).  */
 480
 481 static inline unsigned
 482 number_of_loops (struct function *fn)
 483 {
 484   struct loops *loops = loops_for_fn (fn);
 485   if (!loops)
 486     return 0;
 487
 488   return vec_safe_length (loops->larray);
 489 }
 490
 491 /* Returns true if state of the loops satisfies all properties
 492    described by FLAGS.  */
 493
 494 static inline bool
 495 loops_state_satisfies_p (unsigned flags)
 496 {
 497   return (current_loops->state & flags) == flags;
 498 }
 499
 500 /* Sets FLAGS to the loops state.  */
 501
 502 static inline void
 503 loops_state_set (unsigned flags)
 504 {
 505   current_loops->state |= flags;
 506 }
 507
 508 /* Clears FLAGS from the loops state.  */
 509
 510 static inline void
 511 loops_state_clear (unsigned flags)
 512 {
 513   if (!current_loops)
 514     return;
 515   current_loops->state &= ~flags;
 516 }
 517
 518 /* Loop iterators.  */
 519
 520 /* Flags for loop iteration.  */
 521
 522 enum li_flags
 523 {
 524   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 525   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 526                                    starting from innermost ones.  */
 527   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 528 };
 529
 530 /* The iterator for loops.  */
 531
 532 struct loop_iterator
 533 {
 534   loop_iterator (loop_p *loop, unsigned flags);
 535   ~loop_iterator ();
 536
 537   inline loop_p next ();
 538
 539   /* The list of loops to visit.  */
 540   vec<int> to_visit;
 541
 542   /* The index of the actual loop.  */
 543   unsigned idx;
 544 };
 545
 546 inline loop_p
 547 loop_iterator::next ()
 548 {
 549   int anum;
 550
 551   while (this->to_visit.iterate (this->idx, &anum))
 552     {
 553       this->idx++;
 554       loop_p loop = get_loop (cfun, anum);
 555       if (loop)
 556         return loop;
 557     }
 558
 559   return NULL;
 560 }
 561
 562 inline
 563 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 564 {
 565   struct loop *aloop;
 566   unsigned i;
 567   int mn;
 568
 569   this->idx = 0;
 570   if (!current_loops)
 571     {
 572       this->to_visit.create (0);
 573       *loop = NULL;
 574       return;
 575     }
 576
 577   this->to_visit.create (number_of_loops (cfun));
 578   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 579
 580   if (flags & LI_ONLY_INNERMOST)
 581     {
 582       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 583         if (aloop != NULL
 584             && aloop->inner == NULL
 585             && aloop->num >= mn)
 586           this->to_visit.quick_push (aloop->num);
 587     }
 588   else if (flags & LI_FROM_INNERMOST)
 589     {
 590       /* Push the loops to LI->TO_VISIT in postorder.  */
 591       for (aloop = current_loops->tree_root;
 592            aloop->inner != NULL;
 593            aloop = aloop->inner)
 594         continue;
 595
 596       while (1)
 597         {
 598           if (aloop->num >= mn)
 599             this->to_visit.quick_push (aloop->num);
 600
 601           if (aloop->next)
 602             {
 603               for (aloop = aloop->next;
 604                    aloop->inner != NULL;
 605                    aloop = aloop->inner)
 606                 continue;
 607             }
 608           else if (!loop_outer (aloop))
 609             break;
 610           else
 611             aloop = loop_outer (aloop);
 612         }
 613     }
 614   else
 615     {
 616       /* Push the loops to LI->TO_VISIT in preorder.  */
 617       aloop = current_loops->tree_root;
 618       while (1)
 619         {
 620           if (aloop->num >= mn)
 621             this->to_visit.quick_push (aloop->num);
 622
 623           if (aloop->inner != NULL)
 624             aloop = aloop->inner;
 625           else
 626             {
 627               while (aloop != NULL && aloop->next == NULL)
 628                 aloop = loop_outer (aloop);
 629               if (aloop == NULL)
 630                 break;
 631               aloop = aloop->next;
 632             }
 633         }
 634     }
 635
 636   *loop = this->next ();
 637 }
 638
 639 inline
 640 loop_iterator::~loop_iterator ()
 641 {
 642   this->to_visit.release ();
 643 }
 644
 645 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 646   for (loop_iterator li(&(LOOP), FLAGS); \
 647        (LOOP); \
 648        (LOOP) = li.next ())
 649
 650 /* The properties of the target.  */
 651 struct target_cfgloop {
 652   /* Number of available registers.  */
 653   unsigned x_target_avail_regs;
 654
 655   /* Number of available registers that are call-clobbered.  */
 656   unsigned x_target_clobbered_regs;
 657
 658   /* Number of registers reserved for temporary expressions.  */
 659   unsigned x_target_res_regs;
 660
 661   /* The cost for register when there still is some reserve, but we are
 662      approaching the number of available registers.  */
 663   unsigned x_target_reg_cost[2];
 664
 665   /* The cost for register when we need to spill.  */
 666   unsigned x_target_spill_cost[2];
 667 };
 668
 669 extern struct target_cfgloop default_target_cfgloop;
 670 #if SWITCHABLE_TARGET
 671 extern struct target_cfgloop *this_target_cfgloop;
 672 #else
 673 #define this_target_cfgloop (&default_target_cfgloop)
 674 #endif
 675
 676 #define target_avail_regs \
 677   (this_target_cfgloop->x_target_avail_regs)
 678 #define target_clobbered_regs \
 679   (this_target_cfgloop->x_target_clobbered_regs)
 680 #define target_res_regs \
 681   (this_target_cfgloop->x_target_res_regs)
 682 #define target_reg_cost \
 683   (this_target_cfgloop->x_target_reg_cost)
 684 #define target_spill_cost \
 685   (this_target_cfgloop->x_target_spill_cost)
 686
 687 /* Register pressure estimation for induction variable optimizations & loop
 688    invariant motion.  */
 689 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 690 extern void init_set_costs (void);
 691
 692 /* Loop optimizer initialization.  */
 693 extern void loop_optimizer_init (unsigned);
 694 extern void loop_optimizer_finalize (void);
 695
 696 /* Optimization passes.  */
 697 enum
 698 {
 699   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 700   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 701 };
 702
 703 extern void doloop_optimize_loops (void);
 704 extern void move_loop_invariants (void);
 705 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 706
 707 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 708 static inline struct loop *
 709 loop_outermost (struct loop *loop)
 710 {
 711   unsigned n = vec_safe_length (loop->superloops);
 712
 713   if (n <= 1)
 714     return loop;
 715
 716   return (*loop->superloops)[1];
 717 }
 718
 719 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 720 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 721 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 722 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 723 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 724 extern int bb_loop_depth (const_basic_block);
 725
 726 /* Converts VAL to widest_int.  */
 727
 728 static inline widest_int
 729 gcov_type_to_wide_int (gcov_type val)
 730 {
 731   HOST_WIDE_INT a[2];
 732
 733   a[0] = (unsigned HOST_WIDE_INT) val;
 734   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 735      the size of type.  */
 736   val >>= HOST_BITS_PER_WIDE_INT - 1;
 737   val >>= 1;
 738   a[1] = (unsigned HOST_WIDE_INT) val;
 739
 740   return widest_int::from_array (a, 2);
 741 }
 742 #endif /* GCC_CFGLOOP_H */