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 /* Check loop structure invariants, if internal consistency checks are
 318    enabled.  */
 319
 320 static inline void
 321 checking_verify_loop_structure (void)
 322 {
 323   if (flag_checking)
 324     verify_loop_structure ();
 325 }
 326
 327 /* Loop analysis.  */
 328 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 329 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 330 extern unsigned expected_loop_iterations (const struct loop *);
 331 extern rtx doloop_condition_get (rtx);
 332
 333 void mark_loop_for_removal (loop_p);
 334
 335 /* Induction variable analysis.  */
 336
 337 /* The description of induction variable.  The things are a bit complicated
 338    due to need to handle subregs and extends.  The value of the object described
 339    by it can be obtained as follows (all computations are done in extend_mode):
 340
 341    Value in i-th iteration is
 342      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 343
 344    If first_special is true, the value in the first iteration is
 345      delta + mult * base
 346
 347    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 348      subreg_{mode} (base + i * step)
 349
 350    The get_iv_value function can be used to obtain these expressions.
 351
 352    ??? Add a third mode field that would specify the mode in that inner
 353    computation is done, which would enable it to be different from the
 354    outer one?  */
 355
 356 struct rtx_iv
 357 {
 358   /* Its base and step (mode of base and step is supposed to be extend_mode,
 359      see the description above).  */
 360   rtx base, step;
 361
 362   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 363      or IV_UNKNOWN_EXTEND).  */
 364   enum iv_extend_code extend;
 365
 366   /* Operations applied in the extended mode.  */
 367   rtx delta, mult;
 368
 369   /* The mode it is extended to.  */
 370   machine_mode extend_mode;
 371
 372   /* The mode the variable iterates in.  */
 373   machine_mode mode;
 374
 375   /* Whether the first iteration needs to be handled specially.  */
 376   unsigned first_special : 1;
 377 };
 378
 379 /* The description of an exit from the loop and of the number of iterations
 380    till we take the exit.  */
 381
 382 struct GTY(()) niter_desc
 383 {
 384   /* The edge out of the loop.  */
 385   edge out_edge;
 386
 387   /* The other edge leading from the condition.  */
 388   edge in_edge;
 389
 390   /* True if we are able to say anything about number of iterations of the
 391      loop.  */
 392   bool simple_p;
 393
 394   /* True if the loop iterates the constant number of times.  */
 395   bool const_iter;
 396
 397   /* Number of iterations if constant.  */
 398   uint64_t niter;
 399
 400   /* Assumptions under that the rest of the information is valid.  */
 401   rtx assumptions;
 402
 403   /* Assumptions under that the loop ends before reaching the latch,
 404      even if value of niter_expr says otherwise.  */
 405   rtx noloop_assumptions;
 406
 407   /* Condition under that the loop is infinite.  */
 408   rtx infinite;
 409
 410   /* Whether the comparison is signed.  */
 411   bool signed_p;
 412
 413   /* The mode in that niter_expr should be computed.  */
 414   machine_mode mode;
 415
 416   /* The number of iterations of the loop.  */
 417   rtx niter_expr;
 418 };
 419
 420 extern void iv_analysis_loop_init (struct loop *);
 421 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 422 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 423 extern bool iv_analyze_expr (rtx_insn *, rtx, machine_mode,
 424                              struct rtx_iv *);
 425 extern rtx get_iv_value (struct rtx_iv *, rtx);
 426 extern bool biv_p (rtx_insn *, rtx);
 427 extern void find_simple_exit (struct loop *, struct niter_desc *);
 428 extern void iv_analysis_done (void);
 429
 430 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 431 extern void free_simple_loop_desc (struct loop *loop);
 432
 433 static inline struct niter_desc *
 434 simple_loop_desc (struct loop *loop)
 435 {
 436   return loop->simple_loop_desc;
 437 }
 438
 439 /* Accessors for the loop structures.  */
 440
 441 /* Returns the loop with index NUM from FNs loop tree.  */
 442
 443 static inline struct loop *
 444 get_loop (struct function *fn, unsigned num)
 445 {
 446   return (*loops_for_fn (fn)->larray)[num];
 447 }
 448
 449 /* Returns the number of superloops of LOOP.  */
 450
 451 static inline unsigned
 452 loop_depth (const struct loop *loop)
 453 {
 454   return vec_safe_length (loop->superloops);
 455 }
 456
 457 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 458    loop.  */
 459
 460 static inline struct loop *
 461 loop_outer (const struct loop *loop)
 462 {
 463   unsigned n = vec_safe_length (loop->superloops);
 464
 465   if (n == 0)
 466     return NULL;
 467
 468   return (*loop->superloops)[n - 1];
 469 }
 470
 471 /* Returns true if LOOP has at least one exit edge.  */
 472
 473 static inline bool
 474 loop_has_exit_edges (const struct loop *loop)
 475 {
 476   return loop->exits->next->e != NULL;
 477 }
 478
 479 /* Returns the list of loops in FN.  */
 480
 481 inline vec<loop_p, va_gc> *
 482 get_loops (struct function *fn)
 483 {
 484   struct loops *loops = loops_for_fn (fn);
 485   if (!loops)
 486     return NULL;
 487
 488   return loops->larray;
 489 }
 490
 491 /* Returns the number of loops in FN (including the removed
 492    ones and the fake loop that forms the root of the loop tree).  */
 493
 494 static inline unsigned
 495 number_of_loops (struct function *fn)
 496 {
 497   struct loops *loops = loops_for_fn (fn);
 498   if (!loops)
 499     return 0;
 500
 501   return vec_safe_length (loops->larray);
 502 }
 503
 504 /* Returns true if state of the loops satisfies all properties
 505    described by FLAGS.  */
 506
 507 static inline bool
 508 loops_state_satisfies_p (function *fn, unsigned flags)
 509 {
 510   return (loops_for_fn (fn)->state & flags) == flags;
 511 }
 512
 513 static inline bool
 514 loops_state_satisfies_p (unsigned flags)
 515 {
 516   return loops_state_satisfies_p (cfun, flags);
 517 }
 518
 519 /* Sets FLAGS to the loops state.  */
 520
 521 static inline void
 522 loops_state_set (function *fn, unsigned flags)
 523 {
 524   loops_for_fn (fn)->state |= flags;
 525 }
 526
 527 static inline void
 528 loops_state_set (unsigned flags)
 529 {
 530   loops_state_set (cfun, flags);
 531 }
 532
 533 /* Clears FLAGS from the loops state.  */
 534
 535 static inline void
 536 loops_state_clear (function *fn, unsigned flags)
 537 {
 538   loops_for_fn (fn)->state &= ~flags;
 539 }
 540
 541 static inline void
 542 loops_state_clear (unsigned flags)
 543 {
 544   if (!current_loops)
 545     return;
 546   loops_state_clear (cfun, flags);
 547 }
 548
 549 /* Loop iterators.  */
 550
 551 /* Flags for loop iteration.  */
 552
 553 enum li_flags
 554 {
 555   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 556   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 557                                    starting from innermost ones.  */
 558   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 559 };
 560
 561 /* The iterator for loops.  */
 562
 563 struct loop_iterator
 564 {
 565   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 566   ~loop_iterator ();
 567
 568   inline loop_p next ();
 569
 570   /* The function we are visiting.  */
 571   function *fn;
 572
 573   /* The list of loops to visit.  */
 574   vec<int> to_visit;
 575
 576   /* The index of the actual loop.  */
 577   unsigned idx;
 578 };
 579
 580 inline loop_p
 581 loop_iterator::next ()
 582 {
 583   int anum;
 584
 585   while (this->to_visit.iterate (this->idx, &anum))
 586     {
 587       this->idx++;
 588       loop_p loop = get_loop (fn, anum);
 589       if (loop)
 590         return loop;
 591     }
 592
 593   return NULL;
 594 }
 595
 596 inline
 597 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 598 {
 599   struct loop *aloop;
 600   unsigned i;
 601   int mn;
 602
 603   this->idx = 0;
 604   this->fn = fn;
 605   if (!loops_for_fn (fn))
 606     {
 607       this->to_visit.create (0);
 608       *loop = NULL;
 609       return;
 610     }
 611
 612   this->to_visit.create (number_of_loops (fn));
 613   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 614
 615   if (flags & LI_ONLY_INNERMOST)
 616     {
 617       for (i = 0; vec_safe_iterate (loops_for_fn (fn)->larray, i, &aloop); i++)
 618         if (aloop != NULL
 619             && aloop->inner == NULL
 620             && aloop->num >= mn)
 621           this->to_visit.quick_push (aloop->num);
 622     }
 623   else if (flags & LI_FROM_INNERMOST)
 624     {
 625       /* Push the loops to LI->TO_VISIT in postorder.  */
 626       for (aloop = loops_for_fn (fn)->tree_root;
 627            aloop->inner != NULL;
 628            aloop = aloop->inner)
 629         continue;
 630
 631       while (1)
 632         {
 633           if (aloop->num >= mn)
 634             this->to_visit.quick_push (aloop->num);
 635
 636           if (aloop->next)
 637             {
 638               for (aloop = aloop->next;
 639                    aloop->inner != NULL;
 640                    aloop = aloop->inner)
 641                 continue;
 642             }
 643           else if (!loop_outer (aloop))
 644             break;
 645           else
 646             aloop = loop_outer (aloop);
 647         }
 648     }
 649   else
 650     {
 651       /* Push the loops to LI->TO_VISIT in preorder.  */
 652       aloop = loops_for_fn (fn)->tree_root;
 653       while (1)
 654         {
 655           if (aloop->num >= mn)
 656             this->to_visit.quick_push (aloop->num);
 657
 658           if (aloop->inner != NULL)
 659             aloop = aloop->inner;
 660           else
 661             {
 662               while (aloop != NULL && aloop->next == NULL)
 663                 aloop = loop_outer (aloop);
 664               if (aloop == NULL)
 665                 break;
 666               aloop = aloop->next;
 667             }
 668         }
 669     }
 670
 671   *loop = this->next ();
 672 }
 673
 674 inline
 675 loop_iterator::~loop_iterator ()
 676 {
 677   this->to_visit.release ();
 678 }
 679
 680 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 681   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 682        (LOOP); \
 683        (LOOP) = li.next ())
 684
 685 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 686   for (loop_iterator li(fn, &(LOOP), FLAGS); \
 687        (LOOP); \
 688        (LOOP) = li.next ())
 689
 690 /* The properties of the target.  */
 691 struct target_cfgloop {
 692   /* Number of available registers.  */
 693   unsigned x_target_avail_regs;
 694
 695   /* Number of available registers that are call-clobbered.  */
 696   unsigned x_target_clobbered_regs;
 697
 698   /* Number of registers reserved for temporary expressions.  */
 699   unsigned x_target_res_regs;
 700
 701   /* The cost for register when there still is some reserve, but we are
 702      approaching the number of available registers.  */
 703   unsigned x_target_reg_cost[2];
 704
 705   /* The cost for register when we need to spill.  */
 706   unsigned x_target_spill_cost[2];
 707 };
 708
 709 extern struct target_cfgloop default_target_cfgloop;
 710 #if SWITCHABLE_TARGET
 711 extern struct target_cfgloop *this_target_cfgloop;
 712 #else
 713 #define this_target_cfgloop (&default_target_cfgloop)
 714 #endif
 715
 716 #define target_avail_regs \
 717   (this_target_cfgloop->x_target_avail_regs)
 718 #define target_clobbered_regs \
 719   (this_target_cfgloop->x_target_clobbered_regs)
 720 #define target_res_regs \
 721   (this_target_cfgloop->x_target_res_regs)
 722 #define target_reg_cost \
 723   (this_target_cfgloop->x_target_reg_cost)
 724 #define target_spill_cost \
 725   (this_target_cfgloop->x_target_spill_cost)
 726
 727 /* Register pressure estimation for induction variable optimizations & loop
 728    invariant motion.  */
 729 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 730 extern void init_set_costs (void);
 731
 732 /* Loop optimizer initialization.  */
 733 extern void loop_optimizer_init (unsigned);
 734 extern void loop_optimizer_finalize (function *);
 735 inline void
 736 loop_optimizer_finalize ()
 737 {
 738   loop_optimizer_finalize (cfun);
 739 }
 740
 741 /* Optimization passes.  */
 742 enum
 743 {
 744   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 745   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 746 };
 747
 748 extern void doloop_optimize_loops (void);
 749 extern void move_loop_invariants (void);
 750 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 751
 752 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 753 static inline struct loop *
 754 loop_outermost (struct loop *loop)
 755 {
 756   unsigned n = vec_safe_length (loop->superloops);
 757
 758   if (n <= 1)
 759     return loop;
 760
 761   return (*loop->superloops)[1];
 762 }
 763
 764 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 765 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 766 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 767 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 768 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 769 extern int bb_loop_depth (const_basic_block);
 770
 771 /* Converts VAL to widest_int.  */
 772
 773 static inline widest_int
 774 gcov_type_to_wide_int (gcov_type val)
 775 {
 776   HOST_WIDE_INT a[2];
 777
 778   a[0] = (unsigned HOST_WIDE_INT) val;
 779   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 780      the size of type.  */
 781   val >>= HOST_BITS_PER_WIDE_INT - 1;
 782   val >>= 1;
 783   a[1] = (unsigned HOST_WIDE_INT) val;
 784
 785   return widest_int::from_array (a, 2);
 786 }
 787 #endif /* GCC_CFGLOOP_H */