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
  36 /* Structure to hold decision about unrolling/peeling.  */
  37 enum lpt_dec
  38 {
  39   LPT_NONE,
  40   LPT_UNROLL_CONSTANT,
  41   LPT_UNROLL_RUNTIME,
  42   LPT_UNROLL_STUPID
  43 };
  44
  45 struct GTY (()) lpt_decision {
  46   enum lpt_dec decision;
  47   unsigned times;
  48 };
  49
  50 /* The type of extend applied to an IV.  */
  51 enum iv_extend_code
  52 {
  53   IV_SIGN_EXTEND,
  54   IV_ZERO_EXTEND,
  55   IV_UNKNOWN_EXTEND
  56 };
  57
  58 /* The structure describing a bound on number of iterations of a loop.  */
  59
  60 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  61   /* The statement STMT is executed at most ...  */
  62   gimple stmt;
  63
  64   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  65      The + 1 is added for the following reasons:
  66
  67      a) 0 would otherwise be unused, while we would need to care more about
  68         overflows (as MAX + 1 is sometimes produced as the estimate on number
  69         of executions of STMT).
  70      b) it is consistent with the result of number_of_iterations_exit.  */
  71   widest_int bound;
  72
  73   /* True if the statement will cause the loop to be leaved the (at most)
  74      BOUND + 1-st time it is executed, that is, all the statements after it
  75      are executed at most BOUND times.  */
  76   bool is_exit;
  77
  78   /* The next bound in the list.  */
  79   struct nb_iter_bound *next;
  80 };
  81
  82 /* Description of the loop exit.  */
  83
  84 struct GTY ((for_user)) loop_exit {
  85   /* The exit edge.  */
  86   edge e;
  87
  88   /* Previous and next exit in the list of the exits of the loop.  */
  89   struct loop_exit *prev;
  90   struct loop_exit *next;
  91
  92   /* Next element in the list of loops from that E exits.  */
  93   struct loop_exit *next_e;
  94 };
  95
  96 struct loop_exit_hasher : ggc_hasher<loop_exit *>
  97 {
  98   typedef edge compare_type;
  99
 100   static hashval_t hash (loop_exit *);
 101   static bool equal (loop_exit *, edge);
 102   static void remove (loop_exit *);
 103 };
 104
 105 typedef struct loop *loop_p;
 106
 107 /* An integer estimation of the number of iterations.  Estimate_state
 108    describes what is the state of the estimation.  */
 109 enum loop_estimation
 110 {
 111   /* Estimate was not computed yet.  */
 112   EST_NOT_COMPUTED,
 113   /* Estimate is ready.  */
 114   EST_AVAILABLE,
 115   EST_LAST
 116 };
 117
 118 /* Structure to hold information for each natural loop.  */
 119 struct GTY ((chain_next ("%h.next"))) loop {
 120   /* Index into loops array.  */
 121   int num;
 122
 123   /* Number of loop insns.  */
 124   unsigned ninsns;
 125
 126   /* Basic block of loop header.  */
 127   basic_block header;
 128
 129   /* Basic block of loop latch.  */
 130   basic_block latch;
 131
 132   /* For loop unrolling/peeling decision.  */
 133   struct lpt_decision lpt_decision;
 134
 135   /* Average number of executed insns per iteration.  */
 136   unsigned av_ninsns;
 137
 138   /* Number of blocks contained within the loop.  */
 139   unsigned num_nodes;
 140
 141   /* Superloops of the loop, starting with the outermost loop.  */
 142   vec<loop_p, va_gc> *superloops;
 143
 144   /* The first inner (child) loop or NULL if innermost loop.  */
 145   struct loop *inner;
 146
 147   /* Link to the next (sibling) loop.  */
 148   struct loop *next;
 149
 150   /* Auxiliary info specific to a pass.  */
 151   PTR GTY ((skip (""))) aux;
 152
 153   /* The number of times the latch of the loop is executed.  This can be an
 154      INTEGER_CST, or a symbolic expression representing the number of
 155      iterations like "N - 1", or a COND_EXPR containing the runtime
 156      conditions under which the number of iterations is non zero.
 157
 158      Don't access this field directly: number_of_latch_executions
 159      computes and caches the computed information in this field.  */
 160   tree nb_iterations;
 161
 162   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 163      valid if any_upper_bound is true.  */
 164   widest_int nb_iterations_upper_bound;
 165
 166   /* An integer giving an estimate on nb_iterations.  Unlike
 167      nb_iterations_upper_bound, there is no guarantee that it is at least
 168      nb_iterations.  */
 169   widest_int nb_iterations_estimate;
 170
 171   bool any_upper_bound;
 172   bool any_estimate;
 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   /* 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   /* Head of the cyclic list of the exits of the loop.  */
 206   struct loop_exit *exits;
 207
 208   /* Number of iteration analysis data for RTL.  */
 209   struct niter_desc *simple_loop_desc;
 210
 211   /* For sanity checking during loop fixup we record here the former
 212      loop header for loops marked for removal.  Note that this prevents
 213      the basic-block from being collected but its index can still be
 214      reused.  */
 215   basic_block former_header;
 216 };
 217
 218 /* Flags for state of loop structure.  */
 219 enum
 220 {
 221   LOOPS_HAVE_PREHEADERS = 1,
 222   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 223   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 224   LOOPS_HAVE_RECORDED_EXITS = 8,
 225   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 226   LOOP_CLOSED_SSA = 32,
 227   LOOPS_NEED_FIXUP = 64,
 228   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 229 };
 230
 231 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 232                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 233 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 234
 235 /* Structure to hold CFG information about natural loops within a function.  */
 236 struct GTY (()) loops {
 237   /* State of loops.  */
 238   int state;
 239
 240   /* Array of the loops.  */
 241   vec<loop_p, va_gc> *larray;
 242
 243   /* Maps edges to the list of their descriptions as loop exits.  Edges
 244      whose sources or destinations have loop_father == NULL (which may
 245      happen during the cfg manipulations) should not appear in EXITS.  */
 246   hash_table<loop_exit_hasher> *GTY(()) exits;
 247
 248   /* Pointer to root of loop hierarchy tree.  */
 249   struct loop *tree_root;
 250 };
 251
 252 /* Loop recognition.  */
 253 bool bb_loop_header_p (basic_block);
 254 void init_loops_structure (struct function *, struct loops *, unsigned);
 255 extern struct loops *flow_loops_find (struct loops *);
 256 extern void disambiguate_loops_with_multiple_latches (void);
 257 extern void flow_loops_free (struct loops *);
 258 extern void flow_loops_dump (FILE *,
 259                              void (*)(const struct loop *, FILE *, int), int);
 260 extern void flow_loop_dump (const struct loop *, FILE *,
 261                             void (*)(const struct loop *, FILE *, int), int);
 262 struct loop *alloc_loop (void);
 263 extern void flow_loop_free (struct loop *);
 264 int flow_loop_nodes_find (basic_block, struct loop *);
 265 unsigned fix_loop_structure (bitmap changed_bbs);
 266 bool mark_irreducible_loops (void);
 267 void release_recorded_exits (void);
 268 void record_loop_exits (void);
 269 void rescan_loop_exit (edge, bool, bool);
 270
 271 /* Loop data structure manipulation/querying.  */
 272 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 273 extern void flow_loop_tree_node_remove (struct loop *);
 274 extern void place_new_loop (struct function *, struct loop *);
 275 extern void add_loop (struct loop *, struct loop *);
 276 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 277 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 278 extern struct loop * find_common_loop (struct loop *, struct loop *);
 279 struct loop *superloop_at_depth (struct loop *, unsigned);
 280 struct eni_weights_d;
 281 extern int num_loop_insns (const struct loop *);
 282 extern int average_num_loop_insns (const struct loop *);
 283 extern unsigned get_loop_level (const struct loop *);
 284 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 285 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 286 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 287 extern void mark_loop_exit_edges (void);
 288 extern location_t get_loop_location (struct loop *loop);
 289
 290 /* Loops & cfg manipulation.  */
 291 extern basic_block *get_loop_body (const struct loop *);
 292 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 293                                          unsigned);
 294 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 295 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 296 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 297                                int (*) (const void *, const void *));
 298
 299 extern vec<edge> get_loop_exit_edges (const struct loop *);
 300 extern edge single_exit (const struct loop *);
 301 extern edge single_likely_exit (struct loop *loop);
 302 extern unsigned num_loop_branches (const struct loop *);
 303
 304 extern edge loop_preheader_edge (const struct loop *);
 305 extern edge loop_latch_edge (const struct loop *);
 306
 307 extern void add_bb_to_loop (basic_block, struct loop *);
 308 extern void remove_bb_from_loops (basic_block);
 309
 310 extern void cancel_loop_tree (struct loop *);
 311 extern void delete_loop (struct loop *);
 312
 313 enum
 314 {
 315   CP_SIMPLE_PREHEADERS = 1,
 316   CP_FALLTHRU_PREHEADERS = 2
 317 };
 318
 319 basic_block create_preheader (struct loop *, int);
 320 extern void create_preheaders (int);
 321 extern void force_single_succ_latches (void);
 322
 323 extern void verify_loop_structure (void);
 324
 325 /* Loop analysis.  */
 326 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 327 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 328 extern unsigned expected_loop_iterations (const struct loop *);
 329 extern rtx doloop_condition_get (rtx);
 330
 331
 332 /* Loop manipulation.  */
 333 extern bool can_duplicate_loop_p (const struct loop *loop);
 334
 335 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 336                                            duplicate_loop_to_header_edge.  */
 337 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 338                                            field of newly create BB.  */
 339 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 340                                            a complete peeling.  */
 341
 342 extern edge create_empty_if_region_on_edge (edge, tree);
 343 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 344                                                tree *, tree *, struct loop *);
 345 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 346 extern void copy_loop_info (struct loop *loop, struct loop *target);
 347 extern void duplicate_subloops (struct loop *, struct loop *);
 348 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 349                                            unsigned, sbitmap, edge,
 350                                            vec<edge> *, int);
 351 extern struct loop *loopify (edge, edge,
 352                              basic_block, edge, edge, bool,
 353                              unsigned, unsigned);
 354 struct loop * loop_version (struct loop *, void *,
 355                             basic_block *, unsigned, unsigned, unsigned, bool);
 356 extern bool remove_path (edge);
 357 extern void unloop (struct loop *, bool *, bitmap);
 358 extern void scale_loop_frequencies (struct loop *, int, int);
 359 void mark_loop_for_removal (loop_p);
 360
 361
 362 /* Induction variable analysis.  */
 363
 364 /* The description of induction variable.  The things are a bit complicated
 365    due to need to handle subregs and extends.  The value of the object described
 366    by it can be obtained as follows (all computations are done in extend_mode):
 367
 368    Value in i-th iteration is
 369      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 370
 371    If first_special is true, the value in the first iteration is
 372      delta + mult * base
 373
 374    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 375      subreg_{mode} (base + i * step)
 376
 377    The get_iv_value function can be used to obtain these expressions.
 378
 379    ??? Add a third mode field that would specify the mode in that inner
 380    computation is done, which would enable it to be different from the
 381    outer one?  */
 382
 383 struct rtx_iv
 384 {
 385   /* Its base and step (mode of base and step is supposed to be extend_mode,
 386      see the description above).  */
 387   rtx base, step;
 388
 389   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 390      or IV_UNKNOWN_EXTEND).  */
 391   enum iv_extend_code extend;
 392
 393   /* Operations applied in the extended mode.  */
 394   rtx delta, mult;
 395
 396   /* The mode it is extended to.  */
 397   enum machine_mode extend_mode;
 398
 399   /* The mode the variable iterates in.  */
 400   enum machine_mode mode;
 401
 402   /* Whether the first iteration needs to be handled specially.  */
 403   unsigned first_special : 1;
 404 };
 405
 406 /* The description of an exit from the loop and of the number of iterations
 407    till we take the exit.  */
 408
 409 struct GTY(()) niter_desc
 410 {
 411   /* The edge out of the loop.  */
 412   edge out_edge;
 413
 414   /* The other edge leading from the condition.  */
 415   edge in_edge;
 416
 417   /* True if we are able to say anything about number of iterations of the
 418      loop.  */
 419   bool simple_p;
 420
 421   /* True if the loop iterates the constant number of times.  */
 422   bool const_iter;
 423
 424   /* Number of iterations if constant.  */
 425   uint64_t niter;
 426
 427   /* Assumptions under that the rest of the information is valid.  */
 428   rtx assumptions;
 429
 430   /* Assumptions under that the loop ends before reaching the latch,
 431      even if value of niter_expr says otherwise.  */
 432   rtx noloop_assumptions;
 433
 434   /* Condition under that the loop is infinite.  */
 435   rtx infinite;
 436
 437   /* Whether the comparison is signed.  */
 438   bool signed_p;
 439
 440   /* The mode in that niter_expr should be computed.  */
 441   enum machine_mode mode;
 442
 443   /* The number of iterations of the loop.  */
 444   rtx niter_expr;
 445 };
 446
 447 extern void iv_analysis_loop_init (struct loop *);
 448 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 449 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 450 extern bool iv_analyze_expr (rtx_insn *, rtx, enum machine_mode,
 451                              struct rtx_iv *);
 452 extern rtx get_iv_value (struct rtx_iv *, rtx);
 453 extern bool biv_p (rtx_insn *, rtx);
 454 extern void find_simple_exit (struct loop *, struct niter_desc *);
 455 extern void iv_analysis_done (void);
 456
 457 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 458 extern void free_simple_loop_desc (struct loop *loop);
 459
 460 static inline struct niter_desc *
 461 simple_loop_desc (struct loop *loop)
 462 {
 463   return loop->simple_loop_desc;
 464 }
 465
 466 /* Accessors for the loop structures.  */
 467
 468 /* Returns the loop with index NUM from FNs loop tree.  */
 469
 470 static inline struct loop *
 471 get_loop (struct function *fn, unsigned num)
 472 {
 473   return (*loops_for_fn (fn)->larray)[num];
 474 }
 475
 476 /* Returns the number of superloops of LOOP.  */
 477
 478 static inline unsigned
 479 loop_depth (const struct loop *loop)
 480 {
 481   return vec_safe_length (loop->superloops);
 482 }
 483
 484 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 485    loop.  */
 486
 487 static inline struct loop *
 488 loop_outer (const struct loop *loop)
 489 {
 490   unsigned n = vec_safe_length (loop->superloops);
 491
 492   if (n == 0)
 493     return NULL;
 494
 495   return (*loop->superloops)[n - 1];
 496 }
 497
 498 /* Returns true if LOOP has at least one exit edge.  */
 499
 500 static inline bool
 501 loop_has_exit_edges (const struct loop *loop)
 502 {
 503   return loop->exits->next->e != NULL;
 504 }
 505
 506 /* Returns the list of loops in FN.  */
 507
 508 inline vec<loop_p, va_gc> *
 509 get_loops (struct function *fn)
 510 {
 511   struct loops *loops = loops_for_fn (fn);
 512   if (!loops)
 513     return NULL;
 514
 515   return loops->larray;
 516 }
 517
 518 /* Returns the number of loops in FN (including the removed
 519    ones and the fake loop that forms the root of the loop tree).  */
 520
 521 static inline unsigned
 522 number_of_loops (struct function *fn)
 523 {
 524   struct loops *loops = loops_for_fn (fn);
 525   if (!loops)
 526     return 0;
 527
 528   return vec_safe_length (loops->larray);
 529 }
 530
 531 /* Returns true if state of the loops satisfies all properties
 532    described by FLAGS.  */
 533
 534 static inline bool
 535 loops_state_satisfies_p (unsigned flags)
 536 {
 537   return (current_loops->state & flags) == flags;
 538 }
 539
 540 /* Sets FLAGS to the loops state.  */
 541
 542 static inline void
 543 loops_state_set (unsigned flags)
 544 {
 545   current_loops->state |= flags;
 546 }
 547
 548 /* Clears FLAGS from the loops state.  */
 549
 550 static inline void
 551 loops_state_clear (unsigned flags)
 552 {
 553   if (!current_loops)
 554     return;
 555   current_loops->state &= ~flags;
 556 }
 557
 558 /* Loop iterators.  */
 559
 560 /* Flags for loop iteration.  */
 561
 562 enum li_flags
 563 {
 564   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 565   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 566                                    starting from innermost ones.  */
 567   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 568 };
 569
 570 /* The iterator for loops.  */
 571
 572 struct loop_iterator
 573 {
 574   loop_iterator (loop_p *loop, unsigned flags);
 575   ~loop_iterator ();
 576
 577   inline loop_p next ();
 578
 579   /* The list of loops to visit.  */
 580   vec<int> to_visit;
 581
 582   /* The index of the actual loop.  */
 583   unsigned idx;
 584 };
 585
 586 inline loop_p
 587 loop_iterator::next ()
 588 {
 589   int anum;
 590
 591   while (this->to_visit.iterate (this->idx, &anum))
 592     {
 593       this->idx++;
 594       loop_p loop = get_loop (cfun, anum);
 595       if (loop)
 596         return loop;
 597     }
 598
 599   return NULL;
 600 }
 601
 602 inline
 603 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 604 {
 605   struct loop *aloop;
 606   unsigned i;
 607   int mn;
 608
 609   this->idx = 0;
 610   if (!current_loops)
 611     {
 612       this->to_visit.create (0);
 613       *loop = NULL;
 614       return;
 615     }
 616
 617   this->to_visit.create (number_of_loops (cfun));
 618   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 619
 620   if (flags & LI_ONLY_INNERMOST)
 621     {
 622       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 623         if (aloop != NULL
 624             && aloop->inner == NULL
 625             && aloop->num >= mn)
 626           this->to_visit.quick_push (aloop->num);
 627     }
 628   else if (flags & LI_FROM_INNERMOST)
 629     {
 630       /* Push the loops to LI->TO_VISIT in postorder.  */
 631       for (aloop = current_loops->tree_root;
 632            aloop->inner != NULL;
 633            aloop = aloop->inner)
 634         continue;
 635
 636       while (1)
 637         {
 638           if (aloop->num >= mn)
 639             this->to_visit.quick_push (aloop->num);
 640
 641           if (aloop->next)
 642             {
 643               for (aloop = aloop->next;
 644                    aloop->inner != NULL;
 645                    aloop = aloop->inner)
 646                 continue;
 647             }
 648           else if (!loop_outer (aloop))
 649             break;
 650           else
 651             aloop = loop_outer (aloop);
 652         }
 653     }
 654   else
 655     {
 656       /* Push the loops to LI->TO_VISIT in preorder.  */
 657       aloop = current_loops->tree_root;
 658       while (1)
 659         {
 660           if (aloop->num >= mn)
 661             this->to_visit.quick_push (aloop->num);
 662
 663           if (aloop->inner != NULL)
 664             aloop = aloop->inner;
 665           else
 666             {
 667               while (aloop != NULL && aloop->next == NULL)
 668                 aloop = loop_outer (aloop);
 669               if (aloop == NULL)
 670                 break;
 671               aloop = aloop->next;
 672             }
 673         }
 674     }
 675
 676   *loop = this->next ();
 677 }
 678
 679 inline
 680 loop_iterator::~loop_iterator ()
 681 {
 682   this->to_visit.release ();
 683 }
 684
 685 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 686   for (loop_iterator li(&(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 (void);
 735
 736 /* Optimization passes.  */
 737 enum
 738 {
 739   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 740   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 741 };
 742
 743 extern void doloop_optimize_loops (void);
 744 extern void move_loop_invariants (void);
 745 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 746 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 747
 748 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 749 static inline struct loop *
 750 loop_outermost (struct loop *loop)
 751 {
 752   unsigned n = vec_safe_length (loop->superloops);
 753
 754   if (n <= 1)
 755     return loop;
 756
 757   return (*loop->superloops)[1];
 758 }
 759
 760 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 761 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 762 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 763 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 764 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 765 extern int bb_loop_depth (const_basic_block);
 766
 767 /* Converts VAL to widest_int.  */
 768
 769 static inline widest_int
 770 gcov_type_to_wide_int (gcov_type val)
 771 {
 772   HOST_WIDE_INT a[2];
 773
 774   a[0] = (unsigned HOST_WIDE_INT) val;
 775   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 776      the size of type.  */
 777   val >>= HOST_BITS_PER_WIDE_INT - 1;
 778   val >>= 1;
 779   a[1] = (unsigned HOST_WIDE_INT) val;
 780
 781   return widest_int::from_array (a, 2);
 782 }
 783 #endif /* GCC_CFGLOOP_H */