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_vectorize;
 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
 197 /* Flags for state of loop structure.  */
 198 enum
 199 {
 200   LOOPS_HAVE_PREHEADERS = 1,
 201   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 202   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 203   LOOPS_HAVE_RECORDED_EXITS = 8,
 204   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 205   LOOP_CLOSED_SSA = 32,
 206   LOOPS_NEED_FIXUP = 64,
 207   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 208 };
 209
 210 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 211                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 212 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 213
 214 /* Structure to hold CFG information about natural loops within a function.  */
 215 struct GTY (()) loops {
 216   /* State of loops.  */
 217   int state;
 218
 219   /* Array of the loops.  */
 220   vec<loop_p, va_gc> *larray;
 221
 222   /* Maps edges to the list of their descriptions as loop exits.  Edges
 223      whose sources or destinations have loop_father == NULL (which may
 224      happen during the cfg manipulations) should not appear in EXITS.  */
 225   htab_t GTY((param_is (struct loop_exit))) exits;
 226
 227   /* Pointer to root of loop hierarchy tree.  */
 228   struct loop *tree_root;
 229 };
 230
 231 /* Loop recognition.  */
 232 bool bb_loop_header_p (basic_block);
 233 void init_loops_structure (struct function *, struct loops *, unsigned);
 234 extern struct loops *flow_loops_find (struct loops *);
 235 extern void disambiguate_loops_with_multiple_latches (void);
 236 extern void flow_loops_free (struct loops *);
 237 extern void flow_loops_dump (FILE *,
 238                              void (*)(const struct loop *, FILE *, int), int);
 239 extern void flow_loop_dump (const struct loop *, FILE *,
 240                             void (*)(const struct loop *, FILE *, int), int);
 241 struct loop *alloc_loop (void);
 242 extern void flow_loop_free (struct loop *);
 243 int flow_loop_nodes_find (basic_block, struct loop *);
 244 unsigned fix_loop_structure (bitmap changed_bbs);
 245 bool mark_irreducible_loops (void);
 246 void release_recorded_exits (void);
 247 void record_loop_exits (void);
 248 void rescan_loop_exit (edge, bool, bool);
 249
 250 /* Loop data structure manipulation/querying.  */
 251 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 252 extern void flow_loop_tree_node_remove (struct loop *);
 253 extern void place_new_loop (struct function *, struct loop *);
 254 extern void add_loop (struct loop *, struct loop *);
 255 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 256 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 257 extern struct loop * find_common_loop (struct loop *, struct loop *);
 258 struct loop *superloop_at_depth (struct loop *, unsigned);
 259 struct eni_weights_d;
 260 extern int num_loop_insns (const struct loop *);
 261 extern int average_num_loop_insns (const struct loop *);
 262 extern unsigned get_loop_level (const struct loop *);
 263 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 264 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 265 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 266 extern void mark_loop_exit_edges (void);
 267 extern location_t get_loop_location (struct loop *loop);
 268
 269 /* Loops & cfg manipulation.  */
 270 extern basic_block *get_loop_body (const struct loop *);
 271 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 272                                          unsigned);
 273 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 274 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 275 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 276                                int (*) (const void *, const void *));
 277
 278 extern vec<edge> get_loop_exit_edges (const struct loop *);
 279 extern edge single_exit (const struct loop *);
 280 extern edge single_likely_exit (struct loop *loop);
 281 extern unsigned num_loop_branches (const struct loop *);
 282
 283 extern edge loop_preheader_edge (const struct loop *);
 284 extern edge loop_latch_edge (const struct loop *);
 285
 286 extern void add_bb_to_loop (basic_block, struct loop *);
 287 extern void remove_bb_from_loops (basic_block);
 288
 289 extern void cancel_loop_tree (struct loop *);
 290 extern void delete_loop (struct loop *);
 291
 292 enum
 293 {
 294   CP_SIMPLE_PREHEADERS = 1,
 295   CP_FALLTHRU_PREHEADERS = 2
 296 };
 297
 298 basic_block create_preheader (struct loop *, int);
 299 extern void create_preheaders (int);
 300 extern void force_single_succ_latches (void);
 301
 302 extern void verify_loop_structure (void);
 303
 304 /* Loop analysis.  */
 305 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 306 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 307 extern unsigned expected_loop_iterations (const struct loop *);
 308 extern rtx doloop_condition_get (rtx);
 309
 310
 311 /* Loop manipulation.  */
 312 extern bool can_duplicate_loop_p (const struct loop *loop);
 313
 314 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 315                                            duplicate_loop_to_header_edge.  */
 316 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 317                                            field of newly create BB.  */
 318 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 319                                            a complete peeling.  */
 320
 321 extern edge create_empty_if_region_on_edge (edge, tree);
 322 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 323                                                tree *, tree *, struct loop *);
 324 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 325 extern void copy_loop_info (struct loop *loop, struct loop *target);
 326 extern void duplicate_subloops (struct loop *, struct loop *);
 327 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 328                                            unsigned, sbitmap, edge,
 329                                            vec<edge> *, int);
 330 extern struct loop *loopify (edge, edge,
 331                              basic_block, edge, edge, bool,
 332                              unsigned, unsigned);
 333 struct loop * loop_version (struct loop *, void *,
 334                             basic_block *, unsigned, unsigned, unsigned, bool);
 335 extern bool remove_path (edge);
 336 extern void unloop (struct loop *, bool *, bitmap);
 337 extern void scale_loop_frequencies (struct loop *, int, int);
 338
 339 /* Induction variable analysis.  */
 340
 341 /* The description of induction variable.  The things are a bit complicated
 342    due to need to handle subregs and extends.  The value of the object described
 343    by it can be obtained as follows (all computations are done in extend_mode):
 344
 345    Value in i-th iteration is
 346      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 347
 348    If first_special is true, the value in the first iteration is
 349      delta + mult * base
 350
 351    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 352      subreg_{mode} (base + i * step)
 353
 354    The get_iv_value function can be used to obtain these expressions.
 355
 356    ??? Add a third mode field that would specify the mode in that inner
 357    computation is done, which would enable it to be different from the
 358    outer one?  */
 359
 360 struct rtx_iv
 361 {
 362   /* Its base and step (mode of base and step is supposed to be extend_mode,
 363      see the description above).  */
 364   rtx base, step;
 365
 366   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 367      or IV_UNKNOWN_EXTEND).  */
 368   enum iv_extend_code extend;
 369
 370   /* Operations applied in the extended mode.  */
 371   rtx delta, mult;
 372
 373   /* The mode it is extended to.  */
 374   enum machine_mode extend_mode;
 375
 376   /* The mode the variable iterates in.  */
 377   enum machine_mode mode;
 378
 379   /* Whether the first iteration needs to be handled specially.  */
 380   unsigned first_special : 1;
 381 };
 382
 383 /* The description of an exit from the loop and of the number of iterations
 384    till we take the exit.  */
 385
 386 struct GTY(()) niter_desc
 387 {
 388   /* The edge out of the loop.  */
 389   edge out_edge;
 390
 391   /* The other edge leading from the condition.  */
 392   edge in_edge;
 393
 394   /* True if we are able to say anything about number of iterations of the
 395      loop.  */
 396   bool simple_p;
 397
 398   /* True if the loop iterates the constant number of times.  */
 399   bool const_iter;
 400
 401   /* Number of iterations if constant.  */
 402   unsigned HOST_WIDEST_INT niter;
 403
 404   /* Assumptions under that the rest of the information is valid.  */
 405   rtx assumptions;
 406
 407   /* Assumptions under that the loop ends before reaching the latch,
 408      even if value of niter_expr says otherwise.  */
 409   rtx noloop_assumptions;
 410
 411   /* Condition under that the loop is infinite.  */
 412   rtx infinite;
 413
 414   /* Whether the comparison is signed.  */
 415   bool signed_p;
 416
 417   /* The mode in that niter_expr should be computed.  */
 418   enum machine_mode mode;
 419
 420   /* The number of iterations of the loop.  */
 421   rtx niter_expr;
 422 };
 423
 424 extern void iv_analysis_loop_init (struct loop *);
 425 extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
 426 extern bool iv_analyze_result (rtx, rtx, struct rtx_iv *);
 427 extern bool iv_analyze_expr (rtx, rtx, enum machine_mode, struct rtx_iv *);
 428 extern rtx get_iv_value (struct rtx_iv *, rtx);
 429 extern bool biv_p (rtx, rtx);
 430 extern void find_simple_exit (struct loop *, struct niter_desc *);
 431 extern void iv_analysis_done (void);
 432
 433 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 434 extern void free_simple_loop_desc (struct loop *loop);
 435
 436 static inline struct niter_desc *
 437 simple_loop_desc (struct loop *loop)
 438 {
 439   return loop->simple_loop_desc;
 440 }
 441
 442 /* Accessors for the loop structures.  */
 443
 444 /* Returns the loop with index NUM from FNs loop tree.  */
 445
 446 static inline struct loop *
 447 get_loop (struct function *fn, unsigned num)
 448 {
 449   return (*loops_for_fn (fn)->larray)[num];
 450 }
 451
 452 /* Returns the number of superloops of LOOP.  */
 453
 454 static inline unsigned
 455 loop_depth (const struct loop *loop)
 456 {
 457   return vec_safe_length (loop->superloops);
 458 }
 459
 460 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 461    loop.  */
 462
 463 static inline struct loop *
 464 loop_outer (const struct loop *loop)
 465 {
 466   unsigned n = vec_safe_length (loop->superloops);
 467
 468   if (n == 0)
 469     return NULL;
 470
 471   return (*loop->superloops)[n - 1];
 472 }
 473
 474 /* Returns true if LOOP has at least one exit edge.  */
 475
 476 static inline bool
 477 loop_has_exit_edges (const struct loop *loop)
 478 {
 479   return loop->exits->next->e != NULL;
 480 }
 481
 482 /* Returns the list of loops in FN.  */
 483
 484 inline vec<loop_p, va_gc> *
 485 get_loops (struct function *fn)
 486 {
 487   struct loops *loops = loops_for_fn (fn);
 488   if (!loops)
 489     return NULL;
 490
 491   return loops->larray;
 492 }
 493
 494 /* Returns the number of loops in FN (including the removed
 495    ones and the fake loop that forms the root of the loop tree).  */
 496
 497 static inline unsigned
 498 number_of_loops (struct function *fn)
 499 {
 500   struct loops *loops = loops_for_fn (fn);
 501   if (!loops)
 502     return 0;
 503
 504   return vec_safe_length (loops->larray);
 505 }
 506
 507 /* Returns true if state of the loops satisfies all properties
 508    described by FLAGS.  */
 509
 510 static inline bool
 511 loops_state_satisfies_p (unsigned flags)
 512 {
 513   return (current_loops->state & flags) == flags;
 514 }
 515
 516 /* Sets FLAGS to the loops state.  */
 517
 518 static inline void
 519 loops_state_set (unsigned flags)
 520 {
 521   current_loops->state |= flags;
 522 }
 523
 524 /* Clears FLAGS from the loops state.  */
 525
 526 static inline void
 527 loops_state_clear (unsigned flags)
 528 {
 529   if (!current_loops)
 530     return;
 531   current_loops->state &= ~flags;
 532 }
 533
 534 /* Loop iterators.  */
 535
 536 /* Flags for loop iteration.  */
 537
 538 enum li_flags
 539 {
 540   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 541   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 542                                    starting from innermost ones.  */
 543   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 544 };
 545
 546 /* The iterator for loops.  */
 547
 548 struct loop_iterator
 549 {
 550   loop_iterator (loop_p *loop, unsigned flags);
 551   ~loop_iterator ();
 552
 553   inline loop_p next ();
 554
 555   /* The list of loops to visit.  */
 556   vec<int> to_visit;
 557
 558   /* The index of the actual loop.  */
 559   unsigned idx;
 560 };
 561
 562 inline loop_p
 563 loop_iterator::next ()
 564 {
 565   int anum;
 566
 567   while (this->to_visit.iterate (this->idx, &anum))
 568     {
 569       this->idx++;
 570       loop_p loop = get_loop (cfun, anum);
 571       if (loop)
 572         return loop;
 573     }
 574
 575   return NULL;
 576 }
 577
 578 inline
 579 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 580 {
 581   struct loop *aloop;
 582   unsigned i;
 583   int mn;
 584
 585   this->idx = 0;
 586   if (!current_loops)
 587     {
 588       this->to_visit.create (0);
 589       *loop = NULL;
 590       return;
 591     }
 592
 593   this->to_visit.create (number_of_loops (cfun));
 594   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 595
 596   if (flags & LI_ONLY_INNERMOST)
 597     {
 598       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 599         if (aloop != NULL
 600             && aloop->inner == NULL
 601             && aloop->num >= mn)
 602           this->to_visit.quick_push (aloop->num);
 603     }
 604   else if (flags & LI_FROM_INNERMOST)
 605     {
 606       /* Push the loops to LI->TO_VISIT in postorder.  */
 607       for (aloop = current_loops->tree_root;
 608            aloop->inner != NULL;
 609            aloop = aloop->inner)
 610         continue;
 611
 612       while (1)
 613         {
 614           if (aloop->num >= mn)
 615             this->to_visit.quick_push (aloop->num);
 616
 617           if (aloop->next)
 618             {
 619               for (aloop = aloop->next;
 620                    aloop->inner != NULL;
 621                    aloop = aloop->inner)
 622                 continue;
 623             }
 624           else if (!loop_outer (aloop))
 625             break;
 626           else
 627             aloop = loop_outer (aloop);
 628         }
 629     }
 630   else
 631     {
 632       /* Push the loops to LI->TO_VISIT in preorder.  */
 633       aloop = current_loops->tree_root;
 634       while (1)
 635         {
 636           if (aloop->num >= mn)
 637             this->to_visit.quick_push (aloop->num);
 638
 639           if (aloop->inner != NULL)
 640             aloop = aloop->inner;
 641           else
 642             {
 643               while (aloop != NULL && aloop->next == NULL)
 644                 aloop = loop_outer (aloop);
 645               if (aloop == NULL)
 646                 break;
 647               aloop = aloop->next;
 648             }
 649         }
 650     }
 651
 652   *loop = this->next ();
 653 }
 654
 655 inline
 656 loop_iterator::~loop_iterator ()
 657 {
 658   this->to_visit.release ();
 659 }
 660
 661 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 662   for (loop_iterator li(&(LOOP), FLAGS); \
 663        (LOOP); \
 664        (LOOP) = li.next ())
 665
 666 /* The properties of the target.  */
 667 struct target_cfgloop {
 668   /* Number of available registers.  */
 669   unsigned x_target_avail_regs;
 670
 671   /* Number of available registers that are call-clobbered.  */
 672   unsigned x_target_clobbered_regs;
 673
 674   /* Number of registers reserved for temporary expressions.  */
 675   unsigned x_target_res_regs;
 676
 677   /* The cost for register when there still is some reserve, but we are
 678      approaching the number of available registers.  */
 679   unsigned x_target_reg_cost[2];
 680
 681   /* The cost for register when we need to spill.  */
 682   unsigned x_target_spill_cost[2];
 683 };
 684
 685 extern struct target_cfgloop default_target_cfgloop;
 686 #if SWITCHABLE_TARGET
 687 extern struct target_cfgloop *this_target_cfgloop;
 688 #else
 689 #define this_target_cfgloop (&default_target_cfgloop)
 690 #endif
 691
 692 #define target_avail_regs \
 693   (this_target_cfgloop->x_target_avail_regs)
 694 #define target_clobbered_regs \
 695   (this_target_cfgloop->x_target_clobbered_regs)
 696 #define target_res_regs \
 697   (this_target_cfgloop->x_target_res_regs)
 698 #define target_reg_cost \
 699   (this_target_cfgloop->x_target_reg_cost)
 700 #define target_spill_cost \
 701   (this_target_cfgloop->x_target_spill_cost)
 702
 703 /* Register pressure estimation for induction variable optimizations & loop
 704    invariant motion.  */
 705 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 706 extern void init_set_costs (void);
 707
 708 /* Loop optimizer initialization.  */
 709 extern void loop_optimizer_init (unsigned);
 710 extern void loop_optimizer_finalize (void);
 711
 712 /* Optimization passes.  */
 713 extern void unswitch_loops (void);
 714
 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 *, double_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, double_int *nit);
 744 extern bool get_max_loop_iterations (struct loop *loop, double_int *nit);
 745 extern int bb_loop_depth (const_basic_block);
 746
 747 /* Converts VAL to double_int.  */
 748
 749 static inline double_int
 750 gcov_type_to_double_int (gcov_type val)
 751 {
 752   double_int ret;
 753
 754   ret.low = (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   ret.high = (unsigned HOST_WIDE_INT) val;
 760
 761   return ret;
 762 }
 763 #endif /* GCC_CFGLOOP_H */