gcc-4_9-branch/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 "bitmap.h"
  25 #include "sbitmap.h"
  26 #include "function.h"
  27
  28 /* Structure to hold decision about unrolling/peeling.  */
  29 enum lpt_dec
  30 {
  31   LPT_NONE,
  32   LPT_PEEL_COMPLETELY,
  33   LPT_PEEL_SIMPLE,
  34   LPT_UNROLL_CONSTANT,
  35   LPT_UNROLL_RUNTIME,
  36   LPT_UNROLL_STUPID
  37 };
  38
  39 struct GTY (()) lpt_decision {
  40   enum lpt_dec decision;
  41   unsigned times;
  42 };
  43
  44 /* The type of extend applied to an IV.  */
  45 enum iv_extend_code
  46 {
  47   IV_SIGN_EXTEND,
  48   IV_ZERO_EXTEND,
  49   IV_UNKNOWN_EXTEND
  50 };
  51
  52 /* The structure describing a bound on number of iterations of a loop.  */
  53
  54 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  55   /* The statement STMT is executed at most ...  */
  56   gimple stmt;
  57
  58   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  59      The + 1 is added for the following reasons:
  60
  61      a) 0 would otherwise be unused, while we would need to care more about
  62         overflows (as MAX + 1 is sometimes produced as the estimate on number
  63         of executions of STMT).
  64      b) it is consistent with the result of number_of_iterations_exit.  */
  65   double_int bound;
  66
  67   /* True if the statement will cause the loop to be leaved the (at most)
  68      BOUND + 1-st time it is executed, that is, all the statements after it
  69      are executed at most BOUND times.  */
  70   bool is_exit;
  71
  72   /* The next bound in the list.  */
  73   struct nb_iter_bound *next;
  74 };
  75
  76 /* Description of the loop exit.  */
  77
  78 struct GTY (()) loop_exit {
  79   /* The exit edge.  */
  80   edge e;
  81
  82   /* Previous and next exit in the list of the exits of the loop.  */
  83   struct loop_exit *prev;
  84   struct loop_exit *next;
  85
  86   /* Next element in the list of loops from that E exits.  */
  87   struct loop_exit *next_e;
  88 };
  89
  90 typedef struct loop *loop_p;
  91
  92 /* An integer estimation of the number of iterations.  Estimate_state
  93    describes what is the state of the estimation.  */
  94 enum loop_estimation
  95 {
  96   /* Estimate was not computed yet.  */
  97   EST_NOT_COMPUTED,
  98   /* Estimate is ready.  */
  99   EST_AVAILABLE,
 100   EST_LAST
 101 };
 102
 103 /* Structure to hold information for each natural loop.  */
 104 struct GTY ((chain_next ("%h.next"))) loop {
 105   /* Index into loops array.  */
 106   int num;
 107
 108   /* Number of loop insns.  */
 109   unsigned ninsns;
 110
 111   /* Basic block of loop header.  */
 112   basic_block header;
 113
 114   /* Basic block of loop latch.  */
 115   basic_block latch;
 116
 117   /* For loop unrolling/peeling decision.  */
 118   struct lpt_decision lpt_decision;
 119
 120   /* Average number of executed insns per iteration.  */
 121   unsigned av_ninsns;
 122
 123   /* Number of blocks contained within the loop.  */
 124   unsigned num_nodes;
 125
 126   /* Superloops of the loop, starting with the outermost loop.  */
 127   vec<loop_p, va_gc> *superloops;
 128
 129   /* The first inner (child) loop or NULL if innermost loop.  */
 130   struct loop *inner;
 131
 132   /* Link to the next (sibling) loop.  */
 133   struct loop *next;
 134
 135   /* Auxiliary info specific to a pass.  */
 136   PTR GTY ((skip (""))) aux;
 137
 138   /* The number of times the latch of the loop is executed.  This can be an
 139      INTEGER_CST, or a symbolic expression representing the number of
 140      iterations like "N - 1", or a COND_EXPR containing the runtime
 141      conditions under which the number of iterations is non zero.
 142
 143      Don't access this field directly: number_of_latch_executions
 144      computes and caches the computed information in this field.  */
 145   tree nb_iterations;
 146
 147   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 148      valid if any_upper_bound is true.  */
 149   double_int nb_iterations_upper_bound;
 150
 151   /* An integer giving an estimate on nb_iterations.  Unlike
 152      nb_iterations_upper_bound, there is no guarantee that it is at least
 153      nb_iterations.  */
 154   double_int nb_iterations_estimate;
 155
 156   bool any_upper_bound;
 157   bool any_estimate;
 158
 159   /* True if the loop can be parallel.  */
 160   bool can_be_parallel;
 161
 162   /* True if -Waggressive-loop-optimizations warned about this loop
 163      already.  */
 164   bool warned_aggressive_loop_optimizations;
 165
 166   /* An integer estimation of the number of iterations.  Estimate_state
 167      describes what is the state of the estimation.  */
 168   enum loop_estimation estimate_state;
 169
 170   /* If > 0, an integer, where the user asserted that for any
 171      I in [ 0, nb_iterations ) and for any J in
 172      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 173      of the loop can be safely evaluated concurrently.  */
 174   int safelen;
 175
 176   /* True if we should try harder to vectorize this loop.  */
 177   bool force_vect;
 178
 179   /* True if this loop should never be vectorized.  */
 180   bool dont_vectorize;
 181
 182   /* For SIMD loops, this is a unique identifier of the loop, referenced
 183      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 184      builtins.  */
 185   tree simduid;
 186
 187   /* Upper bound on number of iterations of a loop.  */
 188   struct nb_iter_bound *bounds;
 189
 190   /* Head of the cyclic list of the exits of the loop.  */
 191   struct loop_exit *exits;
 192
 193   /* Number of iteration analysis data for RTL.  */
 194   struct niter_desc *simple_loop_desc;
 195
 196   /* For sanity checking during loop fixup we record here the former
 197      loop header for loops marked for removal.  Note that this prevents
 198      the basic-block from being collected but its index can still be
 199      reused.  */
 200   basic_block former_header;
 201 };
 202
 203 /* Flags for state of loop structure.  */
 204 enum
 205 {
 206   LOOPS_HAVE_PREHEADERS = 1,
 207   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 208   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 209   LOOPS_HAVE_RECORDED_EXITS = 8,
 210   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 211   LOOP_CLOSED_SSA = 32,
 212   LOOPS_NEED_FIXUP = 64,
 213   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 214 };
 215
 216 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 217                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 218 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 219
 220 /* Structure to hold CFG information about natural loops within a function.  */
 221 struct GTY (()) loops {
 222   /* State of loops.  */
 223   int state;
 224
 225   /* Array of the loops.  */
 226   vec<loop_p, va_gc> *larray;
 227
 228   /* Maps edges to the list of their descriptions as loop exits.  Edges
 229      whose sources or destinations have loop_father == NULL (which may
 230      happen during the cfg manipulations) should not appear in EXITS.  */
 231   htab_t GTY((param_is (struct loop_exit))) exits;
 232
 233   /* Pointer to root of loop hierarchy tree.  */
 234   struct loop *tree_root;
 235 };
 236
 237 /* Loop recognition.  */
 238 bool bb_loop_header_p (basic_block);
 239 void init_loops_structure (struct function *, struct loops *, unsigned);
 240 extern struct loops *flow_loops_find (struct loops *);
 241 extern void disambiguate_loops_with_multiple_latches (void);
 242 extern void flow_loops_free (struct loops *);
 243 extern void flow_loops_dump (FILE *,
 244                              void (*)(const struct loop *, FILE *, int), int);
 245 extern void flow_loop_dump (const struct loop *, FILE *,
 246                             void (*)(const struct loop *, FILE *, int), int);
 247 struct loop *alloc_loop (void);
 248 extern void flow_loop_free (struct loop *);
 249 int flow_loop_nodes_find (basic_block, struct loop *);
 250 unsigned fix_loop_structure (bitmap changed_bbs);
 251 bool mark_irreducible_loops (void);
 252 void release_recorded_exits (void);
 253 void record_loop_exits (void);
 254 void rescan_loop_exit (edge, bool, bool);
 255
 256 /* Loop data structure manipulation/querying.  */
 257 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 258 extern void flow_loop_tree_node_remove (struct loop *);
 259 extern void place_new_loop (struct function *, struct loop *);
 260 extern void add_loop (struct loop *, struct loop *);
 261 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 262 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 263 extern struct loop * find_common_loop (struct loop *, struct loop *);
 264 struct loop *superloop_at_depth (struct loop *, unsigned);
 265 struct eni_weights_d;
 266 extern int num_loop_insns (const struct loop *);
 267 extern int average_num_loop_insns (const struct loop *);
 268 extern unsigned get_loop_level (const struct loop *);
 269 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 270 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 271 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 272 extern void mark_loop_exit_edges (void);
 273 extern location_t get_loop_location (struct loop *loop);
 274
 275 /* Loops & cfg manipulation.  */
 276 extern basic_block *get_loop_body (const struct loop *);
 277 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 278                                          unsigned);
 279 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 280 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 281 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 282                                int (*) (const void *, const void *));
 283
 284 extern vec<edge> get_loop_exit_edges (const struct loop *);
 285 extern edge single_exit (const struct loop *);
 286 extern edge single_likely_exit (struct loop *loop);
 287 extern unsigned num_loop_branches (const struct loop *);
 288
 289 extern edge loop_preheader_edge (const struct loop *);
 290 extern edge loop_latch_edge (const struct loop *);
 291
 292 extern void add_bb_to_loop (basic_block, struct loop *);
 293 extern void remove_bb_from_loops (basic_block);
 294
 295 extern void cancel_loop_tree (struct loop *);
 296 extern void delete_loop (struct loop *);
 297
 298 enum
 299 {
 300   CP_SIMPLE_PREHEADERS = 1,
 301   CP_FALLTHRU_PREHEADERS = 2
 302 };
 303
 304 basic_block create_preheader (struct loop *, int);
 305 extern void create_preheaders (int);
 306 extern void force_single_succ_latches (void);
 307
 308 extern void verify_loop_structure (void);
 309
 310 /* Loop analysis.  */
 311 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 312 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 313 extern unsigned expected_loop_iterations (const struct loop *);
 314 extern rtx doloop_condition_get (rtx);
 315
 316
 317 /* Loop manipulation.  */
 318 extern bool can_duplicate_loop_p (const struct loop *loop);
 319
 320 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 321                                            duplicate_loop_to_header_edge.  */
 322 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 323                                            field of newly create BB.  */
 324 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 325                                            a complete peeling.  */
 326
 327 extern edge create_empty_if_region_on_edge (edge, tree);
 328 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 329                                                tree *, tree *, struct loop *);
 330 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 331 extern void copy_loop_info (struct loop *loop, struct loop *target);
 332 extern void duplicate_subloops (struct loop *, struct loop *);
 333 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 334                                            unsigned, sbitmap, edge,
 335                                            vec<edge> *, int);
 336 extern struct loop *loopify (edge, edge,
 337                              basic_block, edge, edge, bool,
 338                              unsigned, unsigned);
 339 struct loop * loop_version (struct loop *, void *,
 340                             basic_block *, unsigned, unsigned, unsigned, bool);
 341 extern bool remove_path (edge);
 342 extern void unloop (struct loop *, bool *, bitmap);
 343 extern void scale_loop_frequencies (struct loop *, int, int);
 344 void mark_loop_for_removal (loop_p);
 345
 346
 347 /* Induction variable analysis.  */
 348
 349 /* The description of induction variable.  The things are a bit complicated
 350    due to need to handle subregs and extends.  The value of the object described
 351    by it can be obtained as follows (all computations are done in extend_mode):
 352
 353    Value in i-th iteration is
 354      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 355
 356    If first_special is true, the value in the first iteration is
 357      delta + mult * base
 358
 359    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 360      subreg_{mode} (base + i * step)
 361
 362    The get_iv_value function can be used to obtain these expressions.
 363
 364    ??? Add a third mode field that would specify the mode in that inner
 365    computation is done, which would enable it to be different from the
 366    outer one?  */
 367
 368 struct rtx_iv
 369 {
 370   /* Its base and step (mode of base and step is supposed to be extend_mode,
 371      see the description above).  */
 372   rtx base, step;
 373
 374   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 375      or IV_UNKNOWN_EXTEND).  */
 376   enum iv_extend_code extend;
 377
 378   /* Operations applied in the extended mode.  */
 379   rtx delta, mult;
 380
 381   /* The mode it is extended to.  */
 382   enum machine_mode extend_mode;
 383
 384   /* The mode the variable iterates in.  */
 385   enum machine_mode mode;
 386
 387   /* Whether the first iteration needs to be handled specially.  */
 388   unsigned first_special : 1;
 389 };
 390
 391 /* The description of an exit from the loop and of the number of iterations
 392    till we take the exit.  */
 393
 394 struct GTY(()) niter_desc
 395 {
 396   /* The edge out of the loop.  */
 397   edge out_edge;
 398
 399   /* The other edge leading from the condition.  */
 400   edge in_edge;
 401
 402   /* True if we are able to say anything about number of iterations of the
 403      loop.  */
 404   bool simple_p;
 405
 406   /* True if the loop iterates the constant number of times.  */
 407   bool const_iter;
 408
 409   /* Number of iterations if constant.  */
 410   unsigned HOST_WIDEST_INT niter;
 411
 412   /* Assumptions under that the rest of the information is valid.  */
 413   rtx assumptions;
 414
 415   /* Assumptions under that the loop ends before reaching the latch,
 416      even if value of niter_expr says otherwise.  */
 417   rtx noloop_assumptions;
 418
 419   /* Condition under that the loop is infinite.  */
 420   rtx infinite;
 421
 422   /* Whether the comparison is signed.  */
 423   bool signed_p;
 424
 425   /* The mode in that niter_expr should be computed.  */
 426   enum machine_mode mode;
 427
 428   /* The number of iterations of the loop.  */
 429   rtx niter_expr;
 430 };
 431
 432 extern void iv_analysis_loop_init (struct loop *);
 433 extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
 434 extern bool iv_analyze_result (rtx, rtx, struct rtx_iv *);
 435 extern bool iv_analyze_expr (rtx, rtx, enum machine_mode, struct rtx_iv *);
 436 extern rtx get_iv_value (struct rtx_iv *, rtx);
 437 extern bool biv_p (rtx, rtx);
 438 extern void find_simple_exit (struct loop *, struct niter_desc *);
 439 extern void iv_analysis_done (void);
 440
 441 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 442 extern void free_simple_loop_desc (struct loop *loop);
 443
 444 static inline struct niter_desc *
 445 simple_loop_desc (struct loop *loop)
 446 {
 447   return loop->simple_loop_desc;
 448 }
 449
 450 /* Accessors for the loop structures.  */
 451
 452 /* Returns the loop with index NUM from FNs loop tree.  */
 453
 454 static inline struct loop *
 455 get_loop (struct function *fn, unsigned num)
 456 {
 457   return (*loops_for_fn (fn)->larray)[num];
 458 }
 459
 460 /* Returns the number of superloops of LOOP.  */
 461
 462 static inline unsigned
 463 loop_depth (const struct loop *loop)
 464 {
 465   return vec_safe_length (loop->superloops);
 466 }
 467
 468 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 469    loop.  */
 470
 471 static inline struct loop *
 472 loop_outer (const struct loop *loop)
 473 {
 474   unsigned n = vec_safe_length (loop->superloops);
 475
 476   if (n == 0)
 477     return NULL;
 478
 479   return (*loop->superloops)[n - 1];
 480 }
 481
 482 /* Returns true if LOOP has at least one exit edge.  */
 483
 484 static inline bool
 485 loop_has_exit_edges (const struct loop *loop)
 486 {
 487   return loop->exits->next->e != NULL;
 488 }
 489
 490 /* Returns the list of loops in FN.  */
 491
 492 inline vec<loop_p, va_gc> *
 493 get_loops (struct function *fn)
 494 {
 495   struct loops *loops = loops_for_fn (fn);
 496   if (!loops)
 497     return NULL;
 498
 499   return loops->larray;
 500 }
 501
 502 /* Returns the number of loops in FN (including the removed
 503    ones and the fake loop that forms the root of the loop tree).  */
 504
 505 static inline unsigned
 506 number_of_loops (struct function *fn)
 507 {
 508   struct loops *loops = loops_for_fn (fn);
 509   if (!loops)
 510     return 0;
 511
 512   return vec_safe_length (loops->larray);
 513 }
 514
 515 /* Returns true if state of the loops satisfies all properties
 516    described by FLAGS.  */
 517
 518 static inline bool
 519 loops_state_satisfies_p (unsigned flags)
 520 {
 521   return (current_loops->state & flags) == flags;
 522 }
 523
 524 /* Sets FLAGS to the loops state.  */
 525
 526 static inline void
 527 loops_state_set (unsigned flags)
 528 {
 529   current_loops->state |= flags;
 530 }
 531
 532 /* Clears FLAGS from the loops state.  */
 533
 534 static inline void
 535 loops_state_clear (unsigned flags)
 536 {
 537   if (!current_loops)
 538     return;
 539   current_loops->state &= ~flags;
 540 }
 541
 542 /* Loop iterators.  */
 543
 544 /* Flags for loop iteration.  */
 545
 546 enum li_flags
 547 {
 548   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 549   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 550                                    starting from innermost ones.  */
 551   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 552 };
 553
 554 /* The iterator for loops.  */
 555
 556 struct loop_iterator
 557 {
 558   loop_iterator (loop_p *loop, unsigned flags);
 559   ~loop_iterator ();
 560
 561   inline loop_p next ();
 562
 563   /* The list of loops to visit.  */
 564   vec<int> to_visit;
 565
 566   /* The index of the actual loop.  */
 567   unsigned idx;
 568 };
 569
 570 inline loop_p
 571 loop_iterator::next ()
 572 {
 573   int anum;
 574
 575   while (this->to_visit.iterate (this->idx, &anum))
 576     {
 577       this->idx++;
 578       loop_p loop = get_loop (cfun, anum);
 579       if (loop)
 580         return loop;
 581     }
 582
 583   return NULL;
 584 }
 585
 586 inline
 587 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 588 {
 589   struct loop *aloop;
 590   unsigned i;
 591   int mn;
 592
 593   this->idx = 0;
 594   if (!current_loops)
 595     {
 596       this->to_visit.create (0);
 597       *loop = NULL;
 598       return;
 599     }
 600
 601   this->to_visit.create (number_of_loops (cfun));
 602   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 603
 604   if (flags & LI_ONLY_INNERMOST)
 605     {
 606       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 607         if (aloop != NULL
 608             && aloop->inner == NULL
 609             && aloop->num >= mn)
 610           this->to_visit.quick_push (aloop->num);
 611     }
 612   else if (flags & LI_FROM_INNERMOST)
 613     {
 614       /* Push the loops to LI->TO_VISIT in postorder.  */
 615       for (aloop = current_loops->tree_root;
 616            aloop->inner != NULL;
 617            aloop = aloop->inner)
 618         continue;
 619
 620       while (1)
 621         {
 622           if (aloop->num >= mn)
 623             this->to_visit.quick_push (aloop->num);
 624
 625           if (aloop->next)
 626             {
 627               for (aloop = aloop->next;
 628                    aloop->inner != NULL;
 629                    aloop = aloop->inner)
 630                 continue;
 631             }
 632           else if (!loop_outer (aloop))
 633             break;
 634           else
 635             aloop = loop_outer (aloop);
 636         }
 637     }
 638   else
 639     {
 640       /* Push the loops to LI->TO_VISIT in preorder.  */
 641       aloop = current_loops->tree_root;
 642       while (1)
 643         {
 644           if (aloop->num >= mn)
 645             this->to_visit.quick_push (aloop->num);
 646
 647           if (aloop->inner != NULL)
 648             aloop = aloop->inner;
 649           else
 650             {
 651               while (aloop != NULL && aloop->next == NULL)
 652                 aloop = loop_outer (aloop);
 653               if (aloop == NULL)
 654                 break;
 655               aloop = aloop->next;
 656             }
 657         }
 658     }
 659
 660   *loop = this->next ();
 661 }
 662
 663 inline
 664 loop_iterator::~loop_iterator ()
 665 {
 666   this->to_visit.release ();
 667 }
 668
 669 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 670   for (loop_iterator li(&(LOOP), FLAGS); \
 671        (LOOP); \
 672        (LOOP) = li.next ())
 673
 674 /* The properties of the target.  */
 675 struct target_cfgloop {
 676   /* Number of available registers.  */
 677   unsigned x_target_avail_regs;
 678
 679   /* Number of available registers that are call-clobbered.  */
 680   unsigned x_target_clobbered_regs;
 681
 682   /* Number of registers reserved for temporary expressions.  */
 683   unsigned x_target_res_regs;
 684
 685   /* The cost for register when there still is some reserve, but we are
 686      approaching the number of available registers.  */
 687   unsigned x_target_reg_cost[2];
 688
 689   /* The cost for register when we need to spill.  */
 690   unsigned x_target_spill_cost[2];
 691 };
 692
 693 extern struct target_cfgloop default_target_cfgloop;
 694 #if SWITCHABLE_TARGET
 695 extern struct target_cfgloop *this_target_cfgloop;
 696 #else
 697 #define this_target_cfgloop (&default_target_cfgloop)
 698 #endif
 699
 700 #define target_avail_regs \
 701   (this_target_cfgloop->x_target_avail_regs)
 702 #define target_clobbered_regs \
 703   (this_target_cfgloop->x_target_clobbered_regs)
 704 #define target_res_regs \
 705   (this_target_cfgloop->x_target_res_regs)
 706 #define target_reg_cost \
 707   (this_target_cfgloop->x_target_reg_cost)
 708 #define target_spill_cost \
 709   (this_target_cfgloop->x_target_spill_cost)
 710
 711 /* Register pressure estimation for induction variable optimizations & loop
 712    invariant motion.  */
 713 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 714 extern void init_set_costs (void);
 715
 716 /* Loop optimizer initialization.  */
 717 extern void loop_optimizer_init (unsigned);
 718 extern void loop_optimizer_finalize (void);
 719
 720 /* Optimization passes.  */
 721 extern void unswitch_loops (void);
 722
 723 enum
 724 {
 725   UAP_PEEL = 1,         /* Enables loop peeling.  */
 726   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 727   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 728 };
 729
 730 extern void unroll_and_peel_loops (int);
 731 extern void doloop_optimize_loops (void);
 732 extern void move_loop_invariants (void);
 733 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 734 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 735
 736 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 737 static inline struct loop *
 738 loop_outermost (struct loop *loop)
 739 {
 740   unsigned n = vec_safe_length (loop->superloops);
 741
 742   if (n <= 1)
 743     return loop;
 744
 745   return (*loop->superloops)[1];
 746 }
 747
 748 extern void record_niter_bound (struct loop *, double_int, bool, bool);
 749 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 750 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 751 extern bool get_estimated_loop_iterations (struct loop *loop, double_int *nit);
 752 extern bool get_max_loop_iterations (struct loop *loop, double_int *nit);
 753 extern int bb_loop_depth (const_basic_block);
 754
 755 /* Converts VAL to double_int.  */
 756
 757 static inline double_int
 758 gcov_type_to_double_int (gcov_type val)
 759 {
 760   double_int ret;
 761
 762   ret.low = (unsigned HOST_WIDE_INT) val;
 763   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 764      the size of type.  */
 765   val >>= HOST_BITS_PER_WIDE_INT - 1;
 766   val >>= 1;
 767   ret.high = (unsigned HOST_WIDE_INT) val;
 768
 769   return ret;
 770 }
 771 #endif /* GCC_CFGLOOP_H */