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