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