gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987-2016 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   widest_int nb_iterations_likely_upper_bound;
 164
 165   /* An integer giving an estimate on nb_iterations.  Unlike
 166      nb_iterations_upper_bound, there is no guarantee that it is at least
 167      nb_iterations.  */
 168   widest_int nb_iterations_estimate;
 169
 170   bool any_upper_bound;
 171   bool any_estimate;
 172   bool any_likely_upper_bound;
 173
 174   /* True if the loop can be parallel.  */
 175   bool can_be_parallel;
 176
 177   /* True if -Waggressive-loop-optimizations warned about this loop
 178      already.  */
 179   bool warned_aggressive_loop_optimizations;
 180
 181   /* An integer estimation of the number of iterations.  Estimate_state
 182      describes what is the state of the estimation.  */
 183   enum loop_estimation estimate_state;
 184
 185   /* If > 0, an integer, where the user asserted that for any
 186      I in [ 0, nb_iterations ) and for any J in
 187      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 188      of the loop can be safely evaluated concurrently.  */
 189   int safelen;
 190
 191   /* True if this loop should never be vectorized.  */
 192   bool dont_vectorize;
 193
 194   /* True if we should try harder to vectorize this loop.  */
 195   bool force_vectorize;
 196
 197   /* True if the loop is part of an oacc kernels region.  */
 198   bool in_oacc_kernels_region;
 199
 200   /* For SIMD loops, this is a unique identifier of the loop, referenced
 201      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 202      builtins.  */
 203   tree simduid;
 204
 205   /* Upper bound on number of iterations of a loop.  */
 206   struct nb_iter_bound *bounds;
 207
 208   /* Non-overflow control ivs of a loop.  */
 209   struct control_iv *control_ivs;
 210
 211   /* Head of the cyclic list of the exits of the loop.  */
 212   struct loop_exit *exits;
 213
 214   /* Number of iteration analysis data for RTL.  */
 215   struct niter_desc *simple_loop_desc;
 216
 217   /* For sanity checking during loop fixup we record here the former
 218      loop header for loops marked for removal.  Note that this prevents
 219      the basic-block from being collected but its index can still be
 220      reused.  */
 221   basic_block former_header;
 222 };
 223
 224 /* Flags for state of loop structure.  */
 225 enum
 226 {
 227   LOOPS_HAVE_PREHEADERS = 1,
 228   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 229   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 230   LOOPS_HAVE_RECORDED_EXITS = 8,
 231   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 232   LOOP_CLOSED_SSA = 32,
 233   LOOPS_NEED_FIXUP = 64,
 234   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 235 };
 236
 237 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 238                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 239 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 240
 241 /* Structure to hold CFG information about natural loops within a function.  */
 242 struct GTY (()) loops {
 243   /* State of loops.  */
 244   int state;
 245
 246   /* Array of the loops.  */
 247   vec<loop_p, va_gc> *larray;
 248
 249   /* Maps edges to the list of their descriptions as loop exits.  Edges
 250      whose sources or destinations have loop_father == NULL (which may
 251      happen during the cfg manipulations) should not appear in EXITS.  */
 252   hash_table<loop_exit_hasher> *GTY(()) exits;
 253
 254   /* Pointer to root of loop hierarchy tree.  */
 255   struct loop *tree_root;
 256 };
 257
 258 /* Loop recognition.  */
 259 bool bb_loop_header_p (basic_block);
 260 void init_loops_structure (struct function *, struct loops *, unsigned);
 261 extern struct loops *flow_loops_find (struct loops *);
 262 extern void disambiguate_loops_with_multiple_latches (void);
 263 extern void flow_loops_free (struct loops *);
 264 extern void flow_loops_dump (FILE *,
 265                              void (*)(const struct loop *, FILE *, int), int);
 266 extern void flow_loop_dump (const struct loop *, FILE *,
 267                             void (*)(const struct loop *, FILE *, int), int);
 268 struct loop *alloc_loop (void);
 269 extern void flow_loop_free (struct loop *);
 270 int flow_loop_nodes_find (basic_block, struct loop *);
 271 unsigned fix_loop_structure (bitmap changed_bbs);
 272 bool mark_irreducible_loops (void);
 273 void release_recorded_exits (function *);
 274 void record_loop_exits (void);
 275 void rescan_loop_exit (edge, bool, bool);
 276
 277 /* Loop data structure manipulation/querying.  */
 278 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 279 extern void flow_loop_tree_node_remove (struct loop *);
 280 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 281 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 282 extern struct loop * find_common_loop (struct loop *, struct loop *);
 283 struct loop *superloop_at_depth (struct loop *, unsigned);
 284 struct eni_weights;
 285 extern int num_loop_insns (const struct loop *);
 286 extern int average_num_loop_insns (const struct loop *);
 287 extern unsigned get_loop_level (const struct loop *);
 288 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 289 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 290 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 291 extern void mark_loop_exit_edges (void);
 292 extern location_t get_loop_location (struct loop *loop);
 293
 294 /* Loops & cfg manipulation.  */
 295 extern basic_block *get_loop_body (const struct loop *);
 296 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 297                                          unsigned);
 298 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 299 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 300 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 301                                int (*) (const void *, const void *));
 302
 303 extern vec<edge> get_loop_exit_edges (const struct loop *);
 304 extern edge single_exit (const struct loop *);
 305 extern edge single_likely_exit (struct loop *loop);
 306 extern unsigned num_loop_branches (const struct loop *);
 307
 308 extern edge loop_preheader_edge (const struct loop *);
 309 extern edge loop_latch_edge (const struct loop *);
 310
 311 extern void add_bb_to_loop (basic_block, struct loop *);
 312 extern void remove_bb_from_loops (basic_block);
 313
 314 extern void cancel_loop_tree (struct loop *);
 315 extern void delete_loop (struct loop *);
 316
 317
 318 extern void verify_loop_structure (void);
 319
 320 /* Loop analysis.  */
 321 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 322 gcov_type expected_loop_iterations_unbounded (const struct loop *,
 323                                               bool *read_profile_p = NULL);
 324 extern unsigned expected_loop_iterations (struct loop *);
 325 extern rtx doloop_condition_get (rtx);
 326
 327 void mark_loop_for_removal (loop_p);
 328
 329 /* Induction variable analysis.  */
 330
 331 /* The description of induction variable.  The things are a bit complicated
 332    due to need to handle subregs and extends.  The value of the object described
 333    by it can be obtained as follows (all computations are done in extend_mode):
 334
 335    Value in i-th iteration is
 336      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 337
 338    If first_special is true, the value in the first iteration is
 339      delta + mult * base
 340
 341    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 342      subreg_{mode} (base + i * step)
 343
 344    The get_iv_value function can be used to obtain these expressions.
 345
 346    ??? Add a third mode field that would specify the mode in that inner
 347    computation is done, which would enable it to be different from the
 348    outer one?  */
 349
 350 struct rtx_iv
 351 {
 352   /* Its base and step (mode of base and step is supposed to be extend_mode,
 353      see the description above).  */
 354   rtx base, step;
 355
 356   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 357      or IV_UNKNOWN_EXTEND).  */
 358   enum iv_extend_code extend;
 359
 360   /* Operations applied in the extended mode.  */
 361   rtx delta, mult;
 362
 363   /* The mode it is extended to.  */
 364   machine_mode extend_mode;
 365
 366   /* The mode the variable iterates in.  */
 367   machine_mode mode;
 368
 369   /* Whether the first iteration needs to be handled specially.  */
 370   unsigned first_special : 1;
 371 };
 372
 373 /* The description of an exit from the loop and of the number of iterations
 374    till we take the exit.  */
 375
 376 struct GTY(()) niter_desc
 377 {
 378   /* The edge out of the loop.  */
 379   edge out_edge;
 380
 381   /* The other edge leading from the condition.  */
 382   edge in_edge;
 383
 384   /* True if we are able to say anything about number of iterations of the
 385      loop.  */
 386   bool simple_p;
 387
 388   /* True if the loop iterates the constant number of times.  */
 389   bool const_iter;
 390
 391   /* Number of iterations if constant.  */
 392   uint64_t niter;
 393
 394   /* Assumptions under that the rest of the information is valid.  */
 395   rtx assumptions;
 396
 397   /* Assumptions under that the loop ends before reaching the latch,
 398      even if value of niter_expr says otherwise.  */
 399   rtx noloop_assumptions;
 400
 401   /* Condition under that the loop is infinite.  */
 402   rtx infinite;
 403
 404   /* Whether the comparison is signed.  */
 405   bool signed_p;
 406
 407   /* The mode in that niter_expr should be computed.  */
 408   machine_mode mode;
 409
 410   /* The number of iterations of the loop.  */
 411   rtx niter_expr;
 412 };
 413
 414 extern void iv_analysis_loop_init (struct loop *);
 415 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 416 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 417 extern bool iv_analyze_expr (rtx_insn *, rtx, machine_mode,
 418                              struct rtx_iv *);
 419 extern rtx get_iv_value (struct rtx_iv *, rtx);
 420 extern bool biv_p (rtx_insn *, rtx);
 421 extern void find_simple_exit (struct loop *, struct niter_desc *);
 422 extern void iv_analysis_done (void);
 423
 424 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 425 extern void free_simple_loop_desc (struct loop *loop);
 426
 427 static inline struct niter_desc *
 428 simple_loop_desc (struct loop *loop)
 429 {
 430   return loop->simple_loop_desc;
 431 }
 432
 433 /* Accessors for the loop structures.  */
 434
 435 /* Returns the loop with index NUM from FNs loop tree.  */
 436
 437 static inline struct loop *
 438 get_loop (struct function *fn, unsigned num)
 439 {
 440   return (*loops_for_fn (fn)->larray)[num];
 441 }
 442
 443 /* Returns the number of superloops of LOOP.  */
 444
 445 static inline unsigned
 446 loop_depth (const struct loop *loop)
 447 {
 448   return vec_safe_length (loop->superloops);
 449 }
 450
 451 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 452    loop.  */
 453
 454 static inline struct loop *
 455 loop_outer (const struct loop *loop)
 456 {
 457   unsigned n = vec_safe_length (loop->superloops);
 458
 459   if (n == 0)
 460     return NULL;
 461
 462   return (*loop->superloops)[n - 1];
 463 }
 464
 465 /* Returns true if LOOP has at least one exit edge.  */
 466
 467 static inline bool
 468 loop_has_exit_edges (const struct loop *loop)
 469 {
 470   return loop->exits->next->e != NULL;
 471 }
 472
 473 /* Returns the list of loops in FN.  */
 474
 475 inline vec<loop_p, va_gc> *
 476 get_loops (struct function *fn)
 477 {
 478   struct loops *loops = loops_for_fn (fn);
 479   if (!loops)
 480     return NULL;
 481
 482   return loops->larray;
 483 }
 484
 485 /* Returns the number of loops in FN (including the removed
 486    ones and the fake loop that forms the root of the loop tree).  */
 487
 488 static inline unsigned
 489 number_of_loops (struct function *fn)
 490 {
 491   struct loops *loops = loops_for_fn (fn);
 492   if (!loops)
 493     return 0;
 494
 495   return vec_safe_length (loops->larray);
 496 }
 497
 498 /* Returns true if state of the loops satisfies all properties
 499    described by FLAGS.  */
 500
 501 static inline bool
 502 loops_state_satisfies_p (function *fn, unsigned flags)
 503 {
 504   return (loops_for_fn (fn)->state & flags) == flags;
 505 }
 506
 507 static inline bool
 508 loops_state_satisfies_p (unsigned flags)
 509 {
 510   return loops_state_satisfies_p (cfun, flags);
 511 }
 512
 513 /* Sets FLAGS to the loops state.  */
 514
 515 static inline void
 516 loops_state_set (function *fn, unsigned flags)
 517 {
 518   loops_for_fn (fn)->state |= flags;
 519 }
 520
 521 static inline void
 522 loops_state_set (unsigned flags)
 523 {
 524   loops_state_set (cfun, flags);
 525 }
 526
 527 /* Clears FLAGS from the loops state.  */
 528
 529 static inline void
 530 loops_state_clear (function *fn, unsigned flags)
 531 {
 532   loops_for_fn (fn)->state &= ~flags;
 533 }
 534
 535 static inline void
 536 loops_state_clear (unsigned flags)
 537 {
 538   if (!current_loops)
 539     return;
 540   loops_state_clear (cfun, flags);
 541 }
 542
 543 /* Check loop structure invariants, if internal consistency checks are
 544    enabled.  */
 545
 546 static inline void
 547 checking_verify_loop_structure (void)
 548 {
 549   /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
 550
 551      The loop optimizers should never make changes to the CFG which
 552      require loop fixups.  But the low level CFG manipulation code may
 553      set the flag conservatively.
 554
 555      Go ahead and clear the flag here.  That avoids the assert inside
 556      VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
 557      structures VERIFY_LOOP_STRUCTURE will detect it.
 558
 559      This also avoid the compile time cost of excessive fixups.  */
 560   loops_state_clear (LOOPS_NEED_FIXUP);
 561   if (flag_checking)
 562     verify_loop_structure ();
 563 }
 564
 565 /* Loop iterators.  */
 566
 567 /* Flags for loop iteration.  */
 568
 569 enum li_flags
 570 {
 571   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 572   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 573                                    starting from innermost ones.  */
 574   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 575 };
 576
 577 /* The iterator for loops.  */
 578
 579 struct loop_iterator
 580 {
 581   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 582   ~loop_iterator ();
 583
 584   inline loop_p next ();
 585
 586   /* The function we are visiting.  */
 587   function *fn;
 588
 589   /* The list of loops to visit.  */
 590   vec<int> to_visit;
 591
 592   /* The index of the actual loop.  */
 593   unsigned idx;
 594 };
 595
 596 inline loop_p
 597 loop_iterator::next ()
 598 {
 599   int anum;
 600
 601   while (this->to_visit.iterate (this->idx, &anum))
 602     {
 603       this->idx++;
 604       loop_p loop = get_loop (fn, anum);
 605       if (loop)
 606         return loop;
 607     }
 608
 609   return NULL;
 610 }
 611
 612 inline
 613 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 614 {
 615   struct loop *aloop;
 616   unsigned i;
 617   int mn;
 618
 619   this->idx = 0;
 620   this->fn = fn;
 621   if (!loops_for_fn (fn))
 622     {
 623       this->to_visit.create (0);
 624       *loop = NULL;
 625       return;
 626     }
 627
 628   this->to_visit.create (number_of_loops (fn));
 629   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 630
 631   if (flags & LI_ONLY_INNERMOST)
 632     {
 633       for (i = 0; vec_safe_iterate (loops_for_fn (fn)->larray, i, &aloop); i++)
 634         if (aloop != NULL
 635             && aloop->inner == NULL
 636             && aloop->num >= mn)
 637           this->to_visit.quick_push (aloop->num);
 638     }
 639   else if (flags & LI_FROM_INNERMOST)
 640     {
 641       /* Push the loops to LI->TO_VISIT in postorder.  */
 642       for (aloop = loops_for_fn (fn)->tree_root;
 643            aloop->inner != NULL;
 644            aloop = aloop->inner)
 645         continue;
 646
 647       while (1)
 648         {
 649           if (aloop->num >= mn)
 650             this->to_visit.quick_push (aloop->num);
 651
 652           if (aloop->next)
 653             {
 654               for (aloop = aloop->next;
 655                    aloop->inner != NULL;
 656                    aloop = aloop->inner)
 657                 continue;
 658             }
 659           else if (!loop_outer (aloop))
 660             break;
 661           else
 662             aloop = loop_outer (aloop);
 663         }
 664     }
 665   else
 666     {
 667       /* Push the loops to LI->TO_VISIT in preorder.  */
 668       aloop = loops_for_fn (fn)->tree_root;
 669       while (1)
 670         {
 671           if (aloop->num >= mn)
 672             this->to_visit.quick_push (aloop->num);
 673
 674           if (aloop->inner != NULL)
 675             aloop = aloop->inner;
 676           else
 677             {
 678               while (aloop != NULL && aloop->next == NULL)
 679                 aloop = loop_outer (aloop);
 680               if (aloop == NULL)
 681                 break;
 682               aloop = aloop->next;
 683             }
 684         }
 685     }
 686
 687   *loop = this->next ();
 688 }
 689
 690 inline
 691 loop_iterator::~loop_iterator ()
 692 {
 693   this->to_visit.release ();
 694 }
 695
 696 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 697   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 698        (LOOP); \
 699        (LOOP) = li.next ())
 700
 701 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 702   for (loop_iterator li(fn, &(LOOP), FLAGS); \
 703        (LOOP); \
 704        (LOOP) = li.next ())
 705
 706 /* The properties of the target.  */
 707 struct target_cfgloop {
 708   /* Number of available registers.  */
 709   unsigned x_target_avail_regs;
 710
 711   /* Number of available registers that are call-clobbered.  */
 712   unsigned x_target_clobbered_regs;
 713
 714   /* Number of registers reserved for temporary expressions.  */
 715   unsigned x_target_res_regs;
 716
 717   /* The cost for register when there still is some reserve, but we are
 718      approaching the number of available registers.  */
 719   unsigned x_target_reg_cost[2];
 720
 721   /* The cost for register when we need to spill.  */
 722   unsigned x_target_spill_cost[2];
 723 };
 724
 725 extern struct target_cfgloop default_target_cfgloop;
 726 #if SWITCHABLE_TARGET
 727 extern struct target_cfgloop *this_target_cfgloop;
 728 #else
 729 #define this_target_cfgloop (&default_target_cfgloop)
 730 #endif
 731
 732 #define target_avail_regs \
 733   (this_target_cfgloop->x_target_avail_regs)
 734 #define target_clobbered_regs \
 735   (this_target_cfgloop->x_target_clobbered_regs)
 736 #define target_res_regs \
 737   (this_target_cfgloop->x_target_res_regs)
 738 #define target_reg_cost \
 739   (this_target_cfgloop->x_target_reg_cost)
 740 #define target_spill_cost \
 741   (this_target_cfgloop->x_target_spill_cost)
 742
 743 /* Register pressure estimation for induction variable optimizations & loop
 744    invariant motion.  */
 745 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 746 extern void init_set_costs (void);
 747
 748 /* Loop optimizer initialization.  */
 749 extern void loop_optimizer_init (unsigned);
 750 extern void loop_optimizer_finalize (function *);
 751 inline void
 752 loop_optimizer_finalize ()
 753 {
 754   loop_optimizer_finalize (cfun);
 755 }
 756
 757 /* Optimization passes.  */
 758 enum
 759 {
 760   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 761   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 762 };
 763
 764 extern void doloop_optimize_loops (void);
 765 extern void move_loop_invariants (void);
 766 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 767
 768 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 769 static inline struct loop *
 770 loop_outermost (struct loop *loop)
 771 {
 772   unsigned n = vec_safe_length (loop->superloops);
 773
 774   if (n <= 1)
 775     return loop;
 776
 777   return (*loop->superloops)[1];
 778 }
 779
 780 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 781 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 782 extern HOST_WIDE_INT get_max_loop_iterations_int (const struct loop *);
 783 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (struct loop *);
 784 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 785 extern bool get_max_loop_iterations (const struct loop *loop, widest_int *nit);
 786 extern bool get_likely_max_loop_iterations (struct loop *loop, widest_int *nit);
 787 extern int bb_loop_depth (const_basic_block);
 788
 789 /* Converts VAL to widest_int.  */
 790
 791 static inline widest_int
 792 gcov_type_to_wide_int (gcov_type val)
 793 {
 794   HOST_WIDE_INT a[2];
 795
 796   a[0] = (unsigned HOST_WIDE_INT) val;
 797   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 798      the size of type.  */
 799   val >>= HOST_BITS_PER_WIDE_INT - 1;
 800   val >>= 1;
 801   a[1] = (unsigned HOST_WIDE_INT) val;
 802
 803   return widest_int::from_array (a, 2);
 804 }
 805 #endif /* GCC_CFGLOOP_H */