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 "function.h"
  28
  29 /* Structure to hold decision about unrolling/peeling.  */
  30 enum lpt_dec
  31 {
  32   LPT_NONE,
  33   LPT_UNROLL_CONSTANT,
  34   LPT_UNROLL_RUNTIME,
  35   LPT_UNROLL_STUPID
  36 };
  37
  38 struct GTY (()) lpt_decision {
  39   enum lpt_dec decision;
  40   unsigned times;
  41 };
  42
  43 /* The type of extend applied to an IV.  */
  44 enum iv_extend_code
  45 {
  46   IV_SIGN_EXTEND,
  47   IV_ZERO_EXTEND,
  48   IV_UNKNOWN_EXTEND
  49 };
  50
  51 /* The structure describing a bound on number of iterations of a loop.  */
  52
  53 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  54   /* The statement STMT is executed at most ...  */
  55   gimple stmt;
  56
  57   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  58      The + 1 is added for the following reasons:
  59
  60      a) 0 would otherwise be unused, while we would need to care more about
  61         overflows (as MAX + 1 is sometimes produced as the estimate on number
  62         of executions of STMT).
  63      b) it is consistent with the result of number_of_iterations_exit.  */
  64   widest_int bound;
  65
  66   /* True if the statement will cause the loop to be leaved the (at most)
  67      BOUND + 1-st time it is executed, that is, all the statements after it
  68      are executed at most BOUND times.  */
  69   bool is_exit;
  70
  71   /* The next bound in the list.  */
  72   struct nb_iter_bound *next;
  73 };
  74
  75 /* Description of the loop exit.  */
  76
  77 struct GTY ((for_user)) loop_exit {
  78   /* The exit edge.  */
  79   edge e;
  80
  81   /* Previous and next exit in the list of the exits of the loop.  */
  82   struct loop_exit *prev;
  83   struct loop_exit *next;
  84
  85   /* Next element in the list of loops from that E exits.  */
  86   struct loop_exit *next_e;
  87 };
  88
  89 struct loop_exit_hasher : ggc_hasher<loop_exit *>
  90 {
  91   typedef edge compare_type;
  92
  93   static hashval_t hash (loop_exit *);
  94   static bool equal (loop_exit *, edge);
  95   static void remove (loop_exit *);
  96 };
  97
  98 typedef struct loop *loop_p;
  99
 100 /* An integer estimation of the number of iterations.  Estimate_state
 101    describes what is the state of the estimation.  */
 102 enum loop_estimation
 103 {
 104   /* Estimate was not computed yet.  */
 105   EST_NOT_COMPUTED,
 106   /* Estimate is ready.  */
 107   EST_AVAILABLE,
 108   EST_LAST
 109 };
 110
 111 /* Structure to hold information for each natural loop.  */
 112 struct GTY ((chain_next ("%h.next"))) loop {
 113   /* Index into loops array.  */
 114   int num;
 115
 116   /* Number of loop insns.  */
 117   unsigned ninsns;
 118
 119   /* Basic block of loop header.  */
 120   basic_block header;
 121
 122   /* Basic block of loop latch.  */
 123   basic_block latch;
 124
 125   /* For loop unrolling/peeling decision.  */
 126   struct lpt_decision lpt_decision;
 127
 128   /* Average number of executed insns per iteration.  */
 129   unsigned av_ninsns;
 130
 131   /* Number of blocks contained within the loop.  */
 132   unsigned num_nodes;
 133
 134   /* Superloops of the loop, starting with the outermost loop.  */
 135   vec<loop_p, va_gc> *superloops;
 136
 137   /* The first inner (child) loop or NULL if innermost loop.  */
 138   struct loop *inner;
 139
 140   /* Link to the next (sibling) loop.  */
 141   struct loop *next;
 142
 143   /* Auxiliary info specific to a pass.  */
 144   PTR GTY ((skip (""))) aux;
 145
 146   /* The number of times the latch of the loop is executed.  This can be an
 147      INTEGER_CST, or a symbolic expression representing the number of
 148      iterations like "N - 1", or a COND_EXPR containing the runtime
 149      conditions under which the number of iterations is non zero.
 150
 151      Don't access this field directly: number_of_latch_executions
 152      computes and caches the computed information in this field.  */
 153   tree nb_iterations;
 154
 155   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 156      valid if any_upper_bound is true.  */
 157   widest_int nb_iterations_upper_bound;
 158
 159   /* An integer giving an estimate on nb_iterations.  Unlike
 160      nb_iterations_upper_bound, there is no guarantee that it is at least
 161      nb_iterations.  */
 162   widest_int nb_iterations_estimate;
 163
 164   bool any_upper_bound;
 165   bool any_estimate;
 166
 167   /* True if the loop can be parallel.  */
 168   bool can_be_parallel;
 169
 170   /* True if -Waggressive-loop-optimizations warned about this loop
 171      already.  */
 172   bool warned_aggressive_loop_optimizations;
 173
 174   /* An integer estimation of the number of iterations.  Estimate_state
 175      describes what is the state of the estimation.  */
 176   enum loop_estimation estimate_state;
 177
 178   /* If > 0, an integer, where the user asserted that for any
 179      I in [ 0, nb_iterations ) and for any J in
 180      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 181      of the loop can be safely evaluated concurrently.  */
 182   int safelen;
 183
 184   /* True if this loop should never be vectorized.  */
 185   bool dont_vectorize;
 186
 187   /* True if we should try harder to vectorize this loop.  */
 188   bool force_vectorize;
 189
 190   /* For SIMD loops, this is a unique identifier of the loop, referenced
 191      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 192      builtins.  */
 193   tree simduid;
 194
 195   /* Upper bound on number of iterations of a loop.  */
 196   struct nb_iter_bound *bounds;
 197
 198   /* Head of the cyclic list of the exits of the loop.  */
 199   struct loop_exit *exits;
 200
 201   /* Number of iteration analysis data for RTL.  */
 202   struct niter_desc *simple_loop_desc;
 203
 204   /* For sanity checking during loop fixup we record here the former
 205      loop header for loops marked for removal.  Note that this prevents
 206      the basic-block from being collected but its index can still be
 207      reused.  */
 208   basic_block former_header;
 209 };
 210
 211 /* Flags for state of loop structure.  */
 212 enum
 213 {
 214   LOOPS_HAVE_PREHEADERS = 1,
 215   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 216   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 217   LOOPS_HAVE_RECORDED_EXITS = 8,
 218   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 219   LOOP_CLOSED_SSA = 32,
 220   LOOPS_NEED_FIXUP = 64,
 221   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 222 };
 223
 224 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 225                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 226 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 227
 228 /* Structure to hold CFG information about natural loops within a function.  */
 229 struct GTY (()) loops {
 230   /* State of loops.  */
 231   int state;
 232
 233   /* Array of the loops.  */
 234   vec<loop_p, va_gc> *larray;
 235
 236   /* Maps edges to the list of their descriptions as loop exits.  Edges
 237      whose sources or destinations have loop_father == NULL (which may
 238      happen during the cfg manipulations) should not appear in EXITS.  */
 239   hash_table<loop_exit_hasher> *GTY(()) exits;
 240
 241   /* Pointer to root of loop hierarchy tree.  */
 242   struct loop *tree_root;
 243 };
 244
 245 /* Loop recognition.  */
 246 bool bb_loop_header_p (basic_block);
 247 void init_loops_structure (struct function *, struct loops *, unsigned);
 248 extern struct loops *flow_loops_find (struct loops *);
 249 extern void disambiguate_loops_with_multiple_latches (void);
 250 extern void flow_loops_free (struct loops *);
 251 extern void flow_loops_dump (FILE *,
 252                              void (*)(const struct loop *, FILE *, int), int);
 253 extern void flow_loop_dump (const struct loop *, FILE *,
 254                             void (*)(const struct loop *, FILE *, int), int);
 255 struct loop *alloc_loop (void);
 256 extern void flow_loop_free (struct loop *);
 257 int flow_loop_nodes_find (basic_block, struct loop *);
 258 unsigned fix_loop_structure (bitmap changed_bbs);
 259 bool mark_irreducible_loops (void);
 260 void release_recorded_exits (void);
 261 void record_loop_exits (void);
 262 void rescan_loop_exit (edge, bool, bool);
 263
 264 /* Loop data structure manipulation/querying.  */
 265 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 266 extern void flow_loop_tree_node_remove (struct loop *);
 267 extern void place_new_loop (struct function *, struct loop *);
 268 extern void add_loop (struct loop *, struct loop *);
 269 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 270 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 271 extern struct loop * find_common_loop (struct loop *, struct loop *);
 272 struct loop *superloop_at_depth (struct loop *, unsigned);
 273 struct eni_weights_d;
 274 extern int num_loop_insns (const struct loop *);
 275 extern int average_num_loop_insns (const struct loop *);
 276 extern unsigned get_loop_level (const struct loop *);
 277 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 278 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 279 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 280 extern void mark_loop_exit_edges (void);
 281 extern location_t get_loop_location (struct loop *loop);
 282
 283 /* Loops & cfg manipulation.  */
 284 extern basic_block *get_loop_body (const struct loop *);
 285 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 286                                          unsigned);
 287 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 288 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 289 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 290                                int (*) (const void *, const void *));
 291
 292 extern vec<edge> get_loop_exit_edges (const struct loop *);
 293 extern edge single_exit (const struct loop *);
 294 extern edge single_likely_exit (struct loop *loop);
 295 extern unsigned num_loop_branches (const struct loop *);
 296
 297 extern edge loop_preheader_edge (const struct loop *);
 298 extern edge loop_latch_edge (const struct loop *);
 299
 300 extern void add_bb_to_loop (basic_block, struct loop *);
 301 extern void remove_bb_from_loops (basic_block);
 302
 303 extern void cancel_loop_tree (struct loop *);
 304 extern void delete_loop (struct loop *);
 305
 306 enum
 307 {
 308   CP_SIMPLE_PREHEADERS = 1,
 309   CP_FALLTHRU_PREHEADERS = 2
 310 };
 311
 312 basic_block create_preheader (struct loop *, int);
 313 extern void create_preheaders (int);
 314 extern void force_single_succ_latches (void);
 315
 316 extern void verify_loop_structure (void);
 317
 318 /* Loop analysis.  */
 319 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 320 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 321 extern unsigned expected_loop_iterations (const struct loop *);
 322 extern rtx doloop_condition_get (rtx);
 323
 324
 325 /* Loop manipulation.  */
 326 extern bool can_duplicate_loop_p (const struct loop *loop);
 327
 328 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 329                                            duplicate_loop_to_header_edge.  */
 330 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 331                                            field of newly create BB.  */
 332 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 333                                            a complete peeling.  */
 334
 335 extern edge create_empty_if_region_on_edge (edge, tree);
 336 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 337                                                tree *, tree *, struct loop *);
 338 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 339 extern void copy_loop_info (struct loop *loop, struct loop *target);
 340 extern void duplicate_subloops (struct loop *, struct loop *);
 341 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 342                                            unsigned, sbitmap, edge,
 343                                            vec<edge> *, int);
 344 extern struct loop *loopify (edge, edge,
 345                              basic_block, edge, edge, bool,
 346                              unsigned, unsigned);
 347 struct loop * loop_version (struct loop *, void *,
 348                             basic_block *, unsigned, unsigned, unsigned, bool);
 349 extern bool remove_path (edge);
 350 extern void unloop (struct loop *, bool *, bitmap);
 351 extern void scale_loop_frequencies (struct loop *, int, int);
 352 void mark_loop_for_removal (loop_p);
 353
 354
 355 /* Induction variable analysis.  */
 356
 357 /* The description of induction variable.  The things are a bit complicated
 358    due to need to handle subregs and extends.  The value of the object described
 359    by it can be obtained as follows (all computations are done in extend_mode):
 360
 361    Value in i-th iteration is
 362      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 363
 364    If first_special is true, the value in the first iteration is
 365      delta + mult * base
 366
 367    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 368      subreg_{mode} (base + i * step)
 369
 370    The get_iv_value function can be used to obtain these expressions.
 371
 372    ??? Add a third mode field that would specify the mode in that inner
 373    computation is done, which would enable it to be different from the
 374    outer one?  */
 375
 376 struct rtx_iv
 377 {
 378   /* Its base and step (mode of base and step is supposed to be extend_mode,
 379      see the description above).  */
 380   rtx base, step;
 381
 382   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 383      or IV_UNKNOWN_EXTEND).  */
 384   enum iv_extend_code extend;
 385
 386   /* Operations applied in the extended mode.  */
 387   rtx delta, mult;
 388
 389   /* The mode it is extended to.  */
 390   enum machine_mode extend_mode;
 391
 392   /* The mode the variable iterates in.  */
 393   enum machine_mode mode;
 394
 395   /* Whether the first iteration needs to be handled specially.  */
 396   unsigned first_special : 1;
 397 };
 398
 399 /* The description of an exit from the loop and of the number of iterations
 400    till we take the exit.  */
 401
 402 struct GTY(()) niter_desc
 403 {
 404   /* The edge out of the loop.  */
 405   edge out_edge;
 406
 407   /* The other edge leading from the condition.  */
 408   edge in_edge;
 409
 410   /* True if we are able to say anything about number of iterations of the
 411      loop.  */
 412   bool simple_p;
 413
 414   /* True if the loop iterates the constant number of times.  */
 415   bool const_iter;
 416
 417   /* Number of iterations if constant.  */
 418   uint64_t niter;
 419
 420   /* Assumptions under that the rest of the information is valid.  */
 421   rtx assumptions;
 422
 423   /* Assumptions under that the loop ends before reaching the latch,
 424      even if value of niter_expr says otherwise.  */
 425   rtx noloop_assumptions;
 426
 427   /* Condition under that the loop is infinite.  */
 428   rtx infinite;
 429
 430   /* Whether the comparison is signed.  */
 431   bool signed_p;
 432
 433   /* The mode in that niter_expr should be computed.  */
 434   enum machine_mode mode;
 435
 436   /* The number of iterations of the loop.  */
 437   rtx niter_expr;
 438 };
 439
 440 extern void iv_analysis_loop_init (struct loop *);
 441 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 442 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 443 extern bool iv_analyze_expr (rtx_insn *, rtx, enum machine_mode,
 444                              struct rtx_iv *);
 445 extern rtx get_iv_value (struct rtx_iv *, rtx);
 446 extern bool biv_p (rtx_insn *, rtx);
 447 extern void find_simple_exit (struct loop *, struct niter_desc *);
 448 extern void iv_analysis_done (void);
 449
 450 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 451 extern void free_simple_loop_desc (struct loop *loop);
 452
 453 static inline struct niter_desc *
 454 simple_loop_desc (struct loop *loop)
 455 {
 456   return loop->simple_loop_desc;
 457 }
 458
 459 /* Accessors for the loop structures.  */
 460
 461 /* Returns the loop with index NUM from FNs loop tree.  */
 462
 463 static inline struct loop *
 464 get_loop (struct function *fn, unsigned num)
 465 {
 466   return (*loops_for_fn (fn)->larray)[num];
 467 }
 468
 469 /* Returns the number of superloops of LOOP.  */
 470
 471 static inline unsigned
 472 loop_depth (const struct loop *loop)
 473 {
 474   return vec_safe_length (loop->superloops);
 475 }
 476
 477 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 478    loop.  */
 479
 480 static inline struct loop *
 481 loop_outer (const struct loop *loop)
 482 {
 483   unsigned n = vec_safe_length (loop->superloops);
 484
 485   if (n == 0)
 486     return NULL;
 487
 488   return (*loop->superloops)[n - 1];
 489 }
 490
 491 /* Returns true if LOOP has at least one exit edge.  */
 492
 493 static inline bool
 494 loop_has_exit_edges (const struct loop *loop)
 495 {
 496   return loop->exits->next->e != NULL;
 497 }
 498
 499 /* Returns the list of loops in FN.  */
 500
 501 inline vec<loop_p, va_gc> *
 502 get_loops (struct function *fn)
 503 {
 504   struct loops *loops = loops_for_fn (fn);
 505   if (!loops)
 506     return NULL;
 507
 508   return loops->larray;
 509 }
 510
 511 /* Returns the number of loops in FN (including the removed
 512    ones and the fake loop that forms the root of the loop tree).  */
 513
 514 static inline unsigned
 515 number_of_loops (struct function *fn)
 516 {
 517   struct loops *loops = loops_for_fn (fn);
 518   if (!loops)
 519     return 0;
 520
 521   return vec_safe_length (loops->larray);
 522 }
 523
 524 /* Returns true if state of the loops satisfies all properties
 525    described by FLAGS.  */
 526
 527 static inline bool
 528 loops_state_satisfies_p (unsigned flags)
 529 {
 530   return (current_loops->state & flags) == flags;
 531 }
 532
 533 /* Sets FLAGS to the loops state.  */
 534
 535 static inline void
 536 loops_state_set (unsigned flags)
 537 {
 538   current_loops->state |= flags;
 539 }
 540
 541 /* Clears FLAGS from the loops state.  */
 542
 543 static inline void
 544 loops_state_clear (unsigned flags)
 545 {
 546   if (!current_loops)
 547     return;
 548   current_loops->state &= ~flags;
 549 }
 550
 551 /* Loop iterators.  */
 552
 553 /* Flags for loop iteration.  */
 554
 555 enum li_flags
 556 {
 557   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 558   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 559                                    starting from innermost ones.  */
 560   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 561 };
 562
 563 /* The iterator for loops.  */
 564
 565 struct loop_iterator
 566 {
 567   loop_iterator (loop_p *loop, unsigned flags);
 568   ~loop_iterator ();
 569
 570   inline loop_p next ();
 571
 572   /* The list of loops to visit.  */
 573   vec<int> to_visit;
 574
 575   /* The index of the actual loop.  */
 576   unsigned idx;
 577 };
 578
 579 inline loop_p
 580 loop_iterator::next ()
 581 {
 582   int anum;
 583
 584   while (this->to_visit.iterate (this->idx, &anum))
 585     {
 586       this->idx++;
 587       loop_p loop = get_loop (cfun, anum);
 588       if (loop)
 589         return loop;
 590     }
 591
 592   return NULL;
 593 }
 594
 595 inline
 596 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 597 {
 598   struct loop *aloop;
 599   unsigned i;
 600   int mn;
 601
 602   this->idx = 0;
 603   if (!current_loops)
 604     {
 605       this->to_visit.create (0);
 606       *loop = NULL;
 607       return;
 608     }
 609
 610   this->to_visit.create (number_of_loops (cfun));
 611   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 612
 613   if (flags & LI_ONLY_INNERMOST)
 614     {
 615       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 616         if (aloop != NULL
 617             && aloop->inner == NULL
 618             && aloop->num >= mn)
 619           this->to_visit.quick_push (aloop->num);
 620     }
 621   else if (flags & LI_FROM_INNERMOST)
 622     {
 623       /* Push the loops to LI->TO_VISIT in postorder.  */
 624       for (aloop = current_loops->tree_root;
 625            aloop->inner != NULL;
 626            aloop = aloop->inner)
 627         continue;
 628
 629       while (1)
 630         {
 631           if (aloop->num >= mn)
 632             this->to_visit.quick_push (aloop->num);
 633
 634           if (aloop->next)
 635             {
 636               for (aloop = aloop->next;
 637                    aloop->inner != NULL;
 638                    aloop = aloop->inner)
 639                 continue;
 640             }
 641           else if (!loop_outer (aloop))
 642             break;
 643           else
 644             aloop = loop_outer (aloop);
 645         }
 646     }
 647   else
 648     {
 649       /* Push the loops to LI->TO_VISIT in preorder.  */
 650       aloop = current_loops->tree_root;
 651       while (1)
 652         {
 653           if (aloop->num >= mn)
 654             this->to_visit.quick_push (aloop->num);
 655
 656           if (aloop->inner != NULL)
 657             aloop = aloop->inner;
 658           else
 659             {
 660               while (aloop != NULL && aloop->next == NULL)
 661                 aloop = loop_outer (aloop);
 662               if (aloop == NULL)
 663                 break;
 664               aloop = aloop->next;
 665             }
 666         }
 667     }
 668
 669   *loop = this->next ();
 670 }
 671
 672 inline
 673 loop_iterator::~loop_iterator ()
 674 {
 675   this->to_visit.release ();
 676 }
 677
 678 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 679   for (loop_iterator li(&(LOOP), FLAGS); \
 680        (LOOP); \
 681        (LOOP) = li.next ())
 682
 683 /* The properties of the target.  */
 684 struct target_cfgloop {
 685   /* Number of available registers.  */
 686   unsigned x_target_avail_regs;
 687
 688   /* Number of available registers that are call-clobbered.  */
 689   unsigned x_target_clobbered_regs;
 690
 691   /* Number of registers reserved for temporary expressions.  */
 692   unsigned x_target_res_regs;
 693
 694   /* The cost for register when there still is some reserve, but we are
 695      approaching the number of available registers.  */
 696   unsigned x_target_reg_cost[2];
 697
 698   /* The cost for register when we need to spill.  */
 699   unsigned x_target_spill_cost[2];
 700 };
 701
 702 extern struct target_cfgloop default_target_cfgloop;
 703 #if SWITCHABLE_TARGET
 704 extern struct target_cfgloop *this_target_cfgloop;
 705 #else
 706 #define this_target_cfgloop (&default_target_cfgloop)
 707 #endif
 708
 709 #define target_avail_regs \
 710   (this_target_cfgloop->x_target_avail_regs)
 711 #define target_clobbered_regs \
 712   (this_target_cfgloop->x_target_clobbered_regs)
 713 #define target_res_regs \
 714   (this_target_cfgloop->x_target_res_regs)
 715 #define target_reg_cost \
 716   (this_target_cfgloop->x_target_reg_cost)
 717 #define target_spill_cost \
 718   (this_target_cfgloop->x_target_spill_cost)
 719
 720 /* Register pressure estimation for induction variable optimizations & loop
 721    invariant motion.  */
 722 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 723 extern void init_set_costs (void);
 724
 725 /* Loop optimizer initialization.  */
 726 extern void loop_optimizer_init (unsigned);
 727 extern void loop_optimizer_finalize (void);
 728
 729 /* Optimization passes.  */
 730 enum
 731 {
 732   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 733   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 734 };
 735
 736 extern void unroll_loops (int);
 737 extern void doloop_optimize_loops (void);
 738 extern void move_loop_invariants (void);
 739 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 740 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 741
 742 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 743 static inline struct loop *
 744 loop_outermost (struct loop *loop)
 745 {
 746   unsigned n = vec_safe_length (loop->superloops);
 747
 748   if (n <= 1)
 749     return loop;
 750
 751   return (*loop->superloops)[1];
 752 }
 753
 754 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 755 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 756 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 757 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 758 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 759 extern int bb_loop_depth (const_basic_block);
 760
 761 /* Converts VAL to widest_int.  */
 762
 763 static inline widest_int
 764 gcov_type_to_wide_int (gcov_type val)
 765 {
 766   HOST_WIDE_INT a[2];
 767
 768   a[0] = (unsigned HOST_WIDE_INT) val;
 769   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 770      the size of type.  */
 771   val >>= HOST_BITS_PER_WIDE_INT - 1;
 772   val >>= 1;
 773   a[1] = (unsigned HOST_WIDE_INT) val;
 774
 775   return widest_int::from_array (a, 2);
 776 }
 777 #endif /* GCC_CFGLOOP_H */