gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987-2014 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 "double-int.h"
  24 #include "wide-int.h"
  25 #include "bitmap.h"
  26 #include "sbitmap.h"
  27 #include "hashtab.h"
  28 #include "hash-set.h"
  29 #include "vec.h"
  30 #include "machmode.h"
  31 #include "tm.h"
  32 #include "hard-reg-set.h"
  33 #include "input.h"
  34 #include "function.h"
  35 #include "cfgloopmanip.h"
  36
  37 /* Structure to hold decision about unrolling/peeling.  */
  38 enum lpt_dec
  39 {
  40   LPT_NONE,
  41   LPT_UNROLL_CONSTANT,
  42   LPT_UNROLL_RUNTIME,
  43   LPT_UNROLL_STUPID
  44 };
  45
  46 struct GTY (()) lpt_decision {
  47   enum lpt_dec decision;
  48   unsigned times;
  49 };
  50
  51 /* The type of extend applied to an IV.  */
  52 enum iv_extend_code
  53 {
  54   IV_SIGN_EXTEND,
  55   IV_ZERO_EXTEND,
  56   IV_UNKNOWN_EXTEND
  57 };
  58
  59 /* The structure describing a bound on number of iterations of a loop.  */
  60
  61 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  62   /* The statement STMT is executed at most ...  */
  63   gimple stmt;
  64
  65   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  66      The + 1 is added for the following reasons:
  67
  68      a) 0 would otherwise be unused, while we would need to care more about
  69         overflows (as MAX + 1 is sometimes produced as the estimate on number
  70         of executions of STMT).
  71      b) it is consistent with the result of number_of_iterations_exit.  */
  72   widest_int bound;
  73
  74   /* True if the statement will cause the loop to be leaved the (at most)
  75      BOUND + 1-st time it is executed, that is, all the statements after it
  76      are executed at most BOUND times.  */
  77   bool is_exit;
  78
  79   /* The next bound in the list.  */
  80   struct nb_iter_bound *next;
  81 };
  82
  83 /* Description of the loop exit.  */
  84
  85 struct GTY ((for_user)) loop_exit {
  86   /* The exit edge.  */
  87   edge e;
  88
  89   /* Previous and next exit in the list of the exits of the loop.  */
  90   struct loop_exit *prev;
  91   struct loop_exit *next;
  92
  93   /* Next element in the list of loops from that E exits.  */
  94   struct loop_exit *next_e;
  95 };
  96
  97 struct loop_exit_hasher : ggc_hasher<loop_exit *>
  98 {
  99   typedef edge compare_type;
 100
 101   static hashval_t hash (loop_exit *);
 102   static bool equal (loop_exit *, edge);
 103   static void remove (loop_exit *);
 104 };
 105
 106 typedef struct loop *loop_p;
 107
 108 /* An integer estimation of the number of iterations.  Estimate_state
 109    describes what is the state of the estimation.  */
 110 enum loop_estimation
 111 {
 112   /* Estimate was not computed yet.  */
 113   EST_NOT_COMPUTED,
 114   /* Estimate is ready.  */
 115   EST_AVAILABLE,
 116   EST_LAST
 117 };
 118
 119 /* Structure to hold information for each natural loop.  */
 120 struct GTY ((chain_next ("%h.next"))) loop {
 121   /* Index into loops array.  */
 122   int num;
 123
 124   /* Number of loop insns.  */
 125   unsigned ninsns;
 126
 127   /* Basic block of loop header.  */
 128   basic_block header;
 129
 130   /* Basic block of loop latch.  */
 131   basic_block latch;
 132
 133   /* For loop unrolling/peeling decision.  */
 134   struct lpt_decision lpt_decision;
 135
 136   /* Average number of executed insns per iteration.  */
 137   unsigned av_ninsns;
 138
 139   /* Number of blocks contained within the loop.  */
 140   unsigned num_nodes;
 141
 142   /* Superloops of the loop, starting with the outermost loop.  */
 143   vec<loop_p, va_gc> *superloops;
 144
 145   /* The first inner (child) loop or NULL if innermost loop.  */
 146   struct loop *inner;
 147
 148   /* Link to the next (sibling) loop.  */
 149   struct loop *next;
 150
 151   /* Auxiliary info specific to a pass.  */
 152   PTR GTY ((skip (""))) aux;
 153
 154   /* The number of times the latch of the loop is executed.  This can be an
 155      INTEGER_CST, or a symbolic expression representing the number of
 156      iterations like "N - 1", or a COND_EXPR containing the runtime
 157      conditions under which the number of iterations is non zero.
 158
 159      Don't access this field directly: number_of_latch_executions
 160      computes and caches the computed information in this field.  */
 161   tree nb_iterations;
 162
 163   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 164      valid if any_upper_bound is true.  */
 165   widest_int nb_iterations_upper_bound;
 166
 167   /* An integer giving an estimate on nb_iterations.  Unlike
 168      nb_iterations_upper_bound, there is no guarantee that it is at least
 169      nb_iterations.  */
 170   widest_int nb_iterations_estimate;
 171
 172   bool any_upper_bound;
 173   bool any_estimate;
 174
 175   /* True if the loop can be parallel.  */
 176   bool can_be_parallel;
 177
 178   /* True if -Waggressive-loop-optimizations warned about this loop
 179      already.  */
 180   bool warned_aggressive_loop_optimizations;
 181
 182   /* An integer estimation of the number of iterations.  Estimate_state
 183      describes what is the state of the estimation.  */
 184   enum loop_estimation estimate_state;
 185
 186   /* If > 0, an integer, where the user asserted that for any
 187      I in [ 0, nb_iterations ) and for any J in
 188      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 189      of the loop can be safely evaluated concurrently.  */
 190   int safelen;
 191
 192   /* True if this loop should never be vectorized.  */
 193   bool dont_vectorize;
 194
 195   /* True if we should try harder to vectorize this loop.  */
 196   bool force_vectorize;
 197
 198   /* For SIMD loops, this is a unique identifier of the loop, referenced
 199      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 200      builtins.  */
 201   tree simduid;
 202
 203   /* Upper bound on number of iterations of a loop.  */
 204   struct nb_iter_bound *bounds;
 205
 206   /* Head of the cyclic list of the exits of the loop.  */
 207   struct loop_exit *exits;
 208
 209   /* Number of iteration analysis data for RTL.  */
 210   struct niter_desc *simple_loop_desc;
 211
 212   /* For sanity checking during loop fixup we record here the former
 213      loop header for loops marked for removal.  Note that this prevents
 214      the basic-block from being collected but its index can still be
 215      reused.  */
 216   basic_block former_header;
 217 };
 218
 219 /* Flags for state of loop structure.  */
 220 enum
 221 {
 222   LOOPS_HAVE_PREHEADERS = 1,
 223   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 224   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 225   LOOPS_HAVE_RECORDED_EXITS = 8,
 226   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 227   LOOP_CLOSED_SSA = 32,
 228   LOOPS_NEED_FIXUP = 64,
 229   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 230 };
 231
 232 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 233                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 234 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 235
 236 /* Structure to hold CFG information about natural loops within a function.  */
 237 struct GTY (()) loops {
 238   /* State of loops.  */
 239   int state;
 240
 241   /* Array of the loops.  */
 242   vec<loop_p, va_gc> *larray;
 243
 244   /* Maps edges to the list of their descriptions as loop exits.  Edges
 245      whose sources or destinations have loop_father == NULL (which may
 246      happen during the cfg manipulations) should not appear in EXITS.  */
 247   hash_table<loop_exit_hasher> *GTY(()) exits;
 248
 249   /* Pointer to root of loop hierarchy tree.  */
 250   struct loop *tree_root;
 251 };
 252
 253 /* Loop recognition.  */
 254 bool bb_loop_header_p (basic_block);
 255 void init_loops_structure (struct function *, struct loops *, unsigned);
 256 extern struct loops *flow_loops_find (struct loops *);
 257 extern void disambiguate_loops_with_multiple_latches (void);
 258 extern void flow_loops_free (struct loops *);
 259 extern void flow_loops_dump (FILE *,
 260                              void (*)(const struct loop *, FILE *, int), int);
 261 extern void flow_loop_dump (const struct loop *, FILE *,
 262                             void (*)(const struct loop *, FILE *, int), int);
 263 struct loop *alloc_loop (void);
 264 extern void flow_loop_free (struct loop *);
 265 int flow_loop_nodes_find (basic_block, struct loop *);
 266 unsigned fix_loop_structure (bitmap changed_bbs);
 267 bool mark_irreducible_loops (void);
 268 void release_recorded_exits (void);
 269 void record_loop_exits (void);
 270 void rescan_loop_exit (edge, bool, bool);
 271
 272 /* Loop data structure manipulation/querying.  */
 273 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 274 extern void flow_loop_tree_node_remove (struct loop *);
 275 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 276 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 277 extern struct loop * find_common_loop (struct loop *, struct loop *);
 278 struct loop *superloop_at_depth (struct loop *, unsigned);
 279 struct eni_weights_d;
 280 extern int num_loop_insns (const struct loop *);
 281 extern int average_num_loop_insns (const struct loop *);
 282 extern unsigned get_loop_level (const struct loop *);
 283 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 284 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 285 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 286 extern void mark_loop_exit_edges (void);
 287 extern location_t get_loop_location (struct loop *loop);
 288
 289 /* Loops & cfg manipulation.  */
 290 extern basic_block *get_loop_body (const struct loop *);
 291 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 292                                          unsigned);
 293 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 294 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 295 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 296                                int (*) (const void *, const void *));
 297
 298 extern vec<edge> get_loop_exit_edges (const struct loop *);
 299 extern edge single_exit (const struct loop *);
 300 extern edge single_likely_exit (struct loop *loop);
 301 extern unsigned num_loop_branches (const struct loop *);
 302
 303 extern edge loop_preheader_edge (const struct loop *);
 304 extern edge loop_latch_edge (const struct loop *);
 305
 306 extern void add_bb_to_loop (basic_block, struct loop *);
 307 extern void remove_bb_from_loops (basic_block);
 308
 309 extern void cancel_loop_tree (struct loop *);
 310 extern void delete_loop (struct loop *);
 311
 312
 313 extern void verify_loop_structure (void);
 314
 315 /* Loop analysis.  */
 316 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 317 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 318 extern unsigned expected_loop_iterations (const struct loop *);
 319 extern rtx doloop_condition_get (rtx);
 320
 321 void mark_loop_for_removal (loop_p);
 322
 323 /* Induction variable analysis.  */
 324
 325 /* The description of induction variable.  The things are a bit complicated
 326    due to need to handle subregs and extends.  The value of the object described
 327    by it can be obtained as follows (all computations are done in extend_mode):
 328
 329    Value in i-th iteration is
 330      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 331
 332    If first_special is true, the value in the first iteration is
 333      delta + mult * base
 334
 335    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 336      subreg_{mode} (base + i * step)
 337
 338    The get_iv_value function can be used to obtain these expressions.
 339
 340    ??? Add a third mode field that would specify the mode in that inner
 341    computation is done, which would enable it to be different from the
 342    outer one?  */
 343
 344 struct rtx_iv
 345 {
 346   /* Its base and step (mode of base and step is supposed to be extend_mode,
 347      see the description above).  */
 348   rtx base, step;
 349
 350   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 351      or IV_UNKNOWN_EXTEND).  */
 352   enum iv_extend_code extend;
 353
 354   /* Operations applied in the extended mode.  */
 355   rtx delta, mult;
 356
 357   /* The mode it is extended to.  */
 358   enum machine_mode extend_mode;
 359
 360   /* The mode the variable iterates in.  */
 361   enum machine_mode mode;
 362
 363   /* Whether the first iteration needs to be handled specially.  */
 364   unsigned first_special : 1;
 365 };
 366
 367 /* The description of an exit from the loop and of the number of iterations
 368    till we take the exit.  */
 369
 370 struct GTY(()) niter_desc
 371 {
 372   /* The edge out of the loop.  */
 373   edge out_edge;
 374
 375   /* The other edge leading from the condition.  */
 376   edge in_edge;
 377
 378   /* True if we are able to say anything about number of iterations of the
 379      loop.  */
 380   bool simple_p;
 381
 382   /* True if the loop iterates the constant number of times.  */
 383   bool const_iter;
 384
 385   /* Number of iterations if constant.  */
 386   uint64_t niter;
 387
 388   /* Assumptions under that the rest of the information is valid.  */
 389   rtx assumptions;
 390
 391   /* Assumptions under that the loop ends before reaching the latch,
 392      even if value of niter_expr says otherwise.  */
 393   rtx noloop_assumptions;
 394
 395   /* Condition under that the loop is infinite.  */
 396   rtx infinite;
 397
 398   /* Whether the comparison is signed.  */
 399   bool signed_p;
 400
 401   /* The mode in that niter_expr should be computed.  */
 402   enum machine_mode mode;
 403
 404   /* The number of iterations of the loop.  */
 405   rtx niter_expr;
 406 };
 407
 408 extern void iv_analysis_loop_init (struct loop *);
 409 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 410 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 411 extern bool iv_analyze_expr (rtx_insn *, rtx, enum machine_mode,
 412                              struct rtx_iv *);
 413 extern rtx get_iv_value (struct rtx_iv *, rtx);
 414 extern bool biv_p (rtx_insn *, rtx);
 415 extern void find_simple_exit (struct loop *, struct niter_desc *);
 416 extern void iv_analysis_done (void);
 417
 418 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 419 extern void free_simple_loop_desc (struct loop *loop);
 420
 421 static inline struct niter_desc *
 422 simple_loop_desc (struct loop *loop)
 423 {
 424   return loop->simple_loop_desc;
 425 }
 426
 427 /* Accessors for the loop structures.  */
 428
 429 /* Returns the loop with index NUM from FNs loop tree.  */
 430
 431 static inline struct loop *
 432 get_loop (struct function *fn, unsigned num)
 433 {
 434   return (*loops_for_fn (fn)->larray)[num];
 435 }
 436
 437 /* Returns the number of superloops of LOOP.  */
 438
 439 static inline unsigned
 440 loop_depth (const struct loop *loop)
 441 {
 442   return vec_safe_length (loop->superloops);
 443 }
 444
 445 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 446    loop.  */
 447
 448 static inline struct loop *
 449 loop_outer (const struct loop *loop)
 450 {
 451   unsigned n = vec_safe_length (loop->superloops);
 452
 453   if (n == 0)
 454     return NULL;
 455
 456   return (*loop->superloops)[n - 1];
 457 }
 458
 459 /* Returns true if LOOP has at least one exit edge.  */
 460
 461 static inline bool
 462 loop_has_exit_edges (const struct loop *loop)
 463 {
 464   return loop->exits->next->e != NULL;
 465 }
 466
 467 /* Returns the list of loops in FN.  */
 468
 469 inline vec<loop_p, va_gc> *
 470 get_loops (struct function *fn)
 471 {
 472   struct loops *loops = loops_for_fn (fn);
 473   if (!loops)
 474     return NULL;
 475
 476   return loops->larray;
 477 }
 478
 479 /* Returns the number of loops in FN (including the removed
 480    ones and the fake loop that forms the root of the loop tree).  */
 481
 482 static inline unsigned
 483 number_of_loops (struct function *fn)
 484 {
 485   struct loops *loops = loops_for_fn (fn);
 486   if (!loops)
 487     return 0;
 488
 489   return vec_safe_length (loops->larray);
 490 }
 491
 492 /* Returns true if state of the loops satisfies all properties
 493    described by FLAGS.  */
 494
 495 static inline bool
 496 loops_state_satisfies_p (unsigned flags)
 497 {
 498   return (current_loops->state & flags) == flags;
 499 }
 500
 501 /* Sets FLAGS to the loops state.  */
 502
 503 static inline void
 504 loops_state_set (unsigned flags)
 505 {
 506   current_loops->state |= flags;
 507 }
 508
 509 /* Clears FLAGS from the loops state.  */
 510
 511 static inline void
 512 loops_state_clear (unsigned flags)
 513 {
 514   if (!current_loops)
 515     return;
 516   current_loops->state &= ~flags;
 517 }
 518
 519 /* Loop iterators.  */
 520
 521 /* Flags for loop iteration.  */
 522
 523 enum li_flags
 524 {
 525   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 526   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 527                                    starting from innermost ones.  */
 528   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 529 };
 530
 531 /* The iterator for loops.  */
 532
 533 struct loop_iterator
 534 {
 535   loop_iterator (loop_p *loop, unsigned flags);
 536   ~loop_iterator ();
 537
 538   inline loop_p next ();
 539
 540   /* The list of loops to visit.  */
 541   vec<int> to_visit;
 542
 543   /* The index of the actual loop.  */
 544   unsigned idx;
 545 };
 546
 547 inline loop_p
 548 loop_iterator::next ()
 549 {
 550   int anum;
 551
 552   while (this->to_visit.iterate (this->idx, &anum))
 553     {
 554       this->idx++;
 555       loop_p loop = get_loop (cfun, anum);
 556       if (loop)
 557         return loop;
 558     }
 559
 560   return NULL;
 561 }
 562
 563 inline
 564 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 565 {
 566   struct loop *aloop;
 567   unsigned i;
 568   int mn;
 569
 570   this->idx = 0;
 571   if (!current_loops)
 572     {
 573       this->to_visit.create (0);
 574       *loop = NULL;
 575       return;
 576     }
 577
 578   this->to_visit.create (number_of_loops (cfun));
 579   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 580
 581   if (flags & LI_ONLY_INNERMOST)
 582     {
 583       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 584         if (aloop != NULL
 585             && aloop->inner == NULL
 586             && aloop->num >= mn)
 587           this->to_visit.quick_push (aloop->num);
 588     }
 589   else if (flags & LI_FROM_INNERMOST)
 590     {
 591       /* Push the loops to LI->TO_VISIT in postorder.  */
 592       for (aloop = current_loops->tree_root;
 593            aloop->inner != NULL;
 594            aloop = aloop->inner)
 595         continue;
 596
 597       while (1)
 598         {
 599           if (aloop->num >= mn)
 600             this->to_visit.quick_push (aloop->num);
 601
 602           if (aloop->next)
 603             {
 604               for (aloop = aloop->next;
 605                    aloop->inner != NULL;
 606                    aloop = aloop->inner)
 607                 continue;
 608             }
 609           else if (!loop_outer (aloop))
 610             break;
 611           else
 612             aloop = loop_outer (aloop);
 613         }
 614     }
 615   else
 616     {
 617       /* Push the loops to LI->TO_VISIT in preorder.  */
 618       aloop = current_loops->tree_root;
 619       while (1)
 620         {
 621           if (aloop->num >= mn)
 622             this->to_visit.quick_push (aloop->num);
 623
 624           if (aloop->inner != NULL)
 625             aloop = aloop->inner;
 626           else
 627             {
 628               while (aloop != NULL && aloop->next == NULL)
 629                 aloop = loop_outer (aloop);
 630               if (aloop == NULL)
 631                 break;
 632               aloop = aloop->next;
 633             }
 634         }
 635     }
 636
 637   *loop = this->next ();
 638 }
 639
 640 inline
 641 loop_iterator::~loop_iterator ()
 642 {
 643   this->to_visit.release ();
 644 }
 645
 646 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 647   for (loop_iterator li(&(LOOP), FLAGS); \
 648        (LOOP); \
 649        (LOOP) = li.next ())
 650
 651 /* The properties of the target.  */
 652 struct target_cfgloop {
 653   /* Number of available registers.  */
 654   unsigned x_target_avail_regs;
 655
 656   /* Number of available registers that are call-clobbered.  */
 657   unsigned x_target_clobbered_regs;
 658
 659   /* Number of registers reserved for temporary expressions.  */
 660   unsigned x_target_res_regs;
 661
 662   /* The cost for register when there still is some reserve, but we are
 663      approaching the number of available registers.  */
 664   unsigned x_target_reg_cost[2];
 665
 666   /* The cost for register when we need to spill.  */
 667   unsigned x_target_spill_cost[2];
 668 };
 669
 670 extern struct target_cfgloop default_target_cfgloop;
 671 #if SWITCHABLE_TARGET
 672 extern struct target_cfgloop *this_target_cfgloop;
 673 #else
 674 #define this_target_cfgloop (&default_target_cfgloop)
 675 #endif
 676
 677 #define target_avail_regs \
 678   (this_target_cfgloop->x_target_avail_regs)
 679 #define target_clobbered_regs \
 680   (this_target_cfgloop->x_target_clobbered_regs)
 681 #define target_res_regs \
 682   (this_target_cfgloop->x_target_res_regs)
 683 #define target_reg_cost \
 684   (this_target_cfgloop->x_target_reg_cost)
 685 #define target_spill_cost \
 686   (this_target_cfgloop->x_target_spill_cost)
 687
 688 /* Register pressure estimation for induction variable optimizations & loop
 689    invariant motion.  */
 690 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 691 extern void init_set_costs (void);
 692
 693 /* Loop optimizer initialization.  */
 694 extern void loop_optimizer_init (unsigned);
 695 extern void loop_optimizer_finalize (void);
 696
 697 /* Optimization passes.  */
 698 enum
 699 {
 700   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 701   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 702 };
 703
 704 extern void doloop_optimize_loops (void);
 705 extern void move_loop_invariants (void);
 706 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 707
 708 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 709 static inline struct loop *
 710 loop_outermost (struct loop *loop)
 711 {
 712   unsigned n = vec_safe_length (loop->superloops);
 713
 714   if (n <= 1)
 715     return loop;
 716
 717   return (*loop->superloops)[1];
 718 }
 719
 720 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 721 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 722 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 723 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 724 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 725 extern int bb_loop_depth (const_basic_block);
 726
 727 /* Converts VAL to widest_int.  */
 728
 729 static inline widest_int
 730 gcov_type_to_wide_int (gcov_type val)
 731 {
 732   HOST_WIDE_INT a[2];
 733
 734   a[0] = (unsigned HOST_WIDE_INT) val;
 735   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 736      the size of type.  */
 737   val >>= HOST_BITS_PER_WIDE_INT - 1;
 738   val >>= 1;
 739   a[1] = (unsigned HOST_WIDE_INT) val;
 740
 741   return widest_int::from_array (a, 2);
 742 }
 743 #endif /* GCC_CFGLOOP_H */