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 #ifdef ENABLE_CHECKING
 198   /* For sanity checking during loop fixup we record here the former
 199      loop header for loops marked for removal.  Note that this prevents
 200      the basic-block from being collected but its index can still be
 201      reused.  */
 202   basic_block former_header;
 203 #endif
 204 };
 205
 206 /* Flags for state of loop structure.  */
 207 enum
 208 {
 209   LOOPS_HAVE_PREHEADERS = 1,
 210   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 211   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 212   LOOPS_HAVE_RECORDED_EXITS = 8,
 213   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 214   LOOP_CLOSED_SSA = 32,
 215   LOOPS_NEED_FIXUP = 64,
 216   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 217 };
 218
 219 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 220                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 221 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 222
 223 /* Structure to hold CFG information about natural loops within a function.  */
 224 struct GTY (()) loops {
 225   /* State of loops.  */
 226   int state;
 227
 228   /* Array of the loops.  */
 229   vec<loop_p, va_gc> *larray;
 230
 231   /* Maps edges to the list of their descriptions as loop exits.  Edges
 232      whose sources or destinations have loop_father == NULL (which may
 233      happen during the cfg manipulations) should not appear in EXITS.  */
 234   htab_t GTY((param_is (struct loop_exit))) exits;
 235
 236   /* Pointer to root of loop hierarchy tree.  */
 237   struct loop *tree_root;
 238 };
 239
 240 /* Loop recognition.  */
 241 bool bb_loop_header_p (basic_block);
 242 void init_loops_structure (struct function *, struct loops *, unsigned);
 243 extern struct loops *flow_loops_find (struct loops *);
 244 extern void disambiguate_loops_with_multiple_latches (void);
 245 extern void flow_loops_free (struct loops *);
 246 extern void flow_loops_dump (FILE *,
 247                              void (*)(const struct loop *, FILE *, int), int);
 248 extern void flow_loop_dump (const struct loop *, FILE *,
 249                             void (*)(const struct loop *, FILE *, int), int);
 250 struct loop *alloc_loop (void);
 251 extern void flow_loop_free (struct loop *);
 252 int flow_loop_nodes_find (basic_block, struct loop *);
 253 unsigned fix_loop_structure (bitmap changed_bbs);
 254 bool mark_irreducible_loops (void);
 255 void release_recorded_exits (void);
 256 void record_loop_exits (void);
 257 void rescan_loop_exit (edge, bool, bool);
 258
 259 /* Loop data structure manipulation/querying.  */
 260 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 261 extern void flow_loop_tree_node_remove (struct loop *);
 262 extern void place_new_loop (struct function *, struct loop *);
 263 extern void add_loop (struct loop *, struct loop *);
 264 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 265 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 266 extern struct loop * find_common_loop (struct loop *, struct loop *);
 267 struct loop *superloop_at_depth (struct loop *, unsigned);
 268 struct eni_weights_d;
 269 extern int num_loop_insns (const struct loop *);
 270 extern int average_num_loop_insns (const struct loop *);
 271 extern unsigned get_loop_level (const struct loop *);
 272 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 273 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 274 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 275 extern void mark_loop_exit_edges (void);
 276 extern location_t get_loop_location (struct loop *loop);
 277
 278 /* Loops & cfg manipulation.  */
 279 extern basic_block *get_loop_body (const struct loop *);
 280 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 281                                          unsigned);
 282 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 283 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 284 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 285                                int (*) (const void *, const void *));
 286
 287 extern vec<edge> get_loop_exit_edges (const struct loop *);
 288 extern edge single_exit (const struct loop *);
 289 extern edge single_likely_exit (struct loop *loop);
 290 extern unsigned num_loop_branches (const struct loop *);
 291
 292 extern edge loop_preheader_edge (const struct loop *);
 293 extern edge loop_latch_edge (const struct loop *);
 294
 295 extern void add_bb_to_loop (basic_block, struct loop *);
 296 extern void remove_bb_from_loops (basic_block);
 297
 298 extern void cancel_loop_tree (struct loop *);
 299 extern void delete_loop (struct loop *);
 300
 301 enum
 302 {
 303   CP_SIMPLE_PREHEADERS = 1,
 304   CP_FALLTHRU_PREHEADERS = 2
 305 };
 306
 307 basic_block create_preheader (struct loop *, int);
 308 extern void create_preheaders (int);
 309 extern void force_single_succ_latches (void);
 310
 311 extern void verify_loop_structure (void);
 312
 313 /* Loop analysis.  */
 314 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 315 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 316 extern unsigned expected_loop_iterations (const struct loop *);
 317 extern rtx doloop_condition_get (rtx);
 318
 319
 320 /* Loop manipulation.  */
 321 extern bool can_duplicate_loop_p (const struct loop *loop);
 322
 323 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 324                                            duplicate_loop_to_header_edge.  */
 325 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 326                                            field of newly create BB.  */
 327 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 328                                            a complete peeling.  */
 329
 330 extern edge create_empty_if_region_on_edge (edge, tree);
 331 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 332                                                tree *, tree *, struct loop *);
 333 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 334 extern void copy_loop_info (struct loop *loop, struct loop *target);
 335 extern void duplicate_subloops (struct loop *, struct loop *);
 336 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 337                                            unsigned, sbitmap, edge,
 338                                            vec<edge> *, int);
 339 extern struct loop *loopify (edge, edge,
 340                              basic_block, edge, edge, bool,
 341                              unsigned, unsigned);
 342 struct loop * loop_version (struct loop *, void *,
 343                             basic_block *, unsigned, unsigned, unsigned, bool);
 344 extern bool remove_path (edge);
 345 extern void unloop (struct loop *, bool *, bitmap);
 346 extern void scale_loop_frequencies (struct loop *, int, int);
 347 void mark_loop_for_removal (loop_p);
 348
 349
 350 /* Induction variable analysis.  */
 351
 352 /* The description of induction variable.  The things are a bit complicated
 353    due to need to handle subregs and extends.  The value of the object described
 354    by it can be obtained as follows (all computations are done in extend_mode):
 355
 356    Value in i-th iteration is
 357      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 358
 359    If first_special is true, the value in the first iteration is
 360      delta + mult * base
 361
 362    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 363      subreg_{mode} (base + i * step)
 364
 365    The get_iv_value function can be used to obtain these expressions.
 366
 367    ??? Add a third mode field that would specify the mode in that inner
 368    computation is done, which would enable it to be different from the
 369    outer one?  */
 370
 371 struct rtx_iv
 372 {
 373   /* Its base and step (mode of base and step is supposed to be extend_mode,
 374      see the description above).  */
 375   rtx base, step;
 376
 377   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 378      or IV_UNKNOWN_EXTEND).  */
 379   enum iv_extend_code extend;
 380
 381   /* Operations applied in the extended mode.  */
 382   rtx delta, mult;
 383
 384   /* The mode it is extended to.  */
 385   enum machine_mode extend_mode;
 386
 387   /* The mode the variable iterates in.  */
 388   enum machine_mode mode;
 389
 390   /* Whether the first iteration needs to be handled specially.  */
 391   unsigned first_special : 1;
 392 };
 393
 394 /* The description of an exit from the loop and of the number of iterations
 395    till we take the exit.  */
 396
 397 struct GTY(()) niter_desc
 398 {
 399   /* The edge out of the loop.  */
 400   edge out_edge;
 401
 402   /* The other edge leading from the condition.  */
 403   edge in_edge;
 404
 405   /* True if we are able to say anything about number of iterations of the
 406      loop.  */
 407   bool simple_p;
 408
 409   /* True if the loop iterates the constant number of times.  */
 410   bool const_iter;
 411
 412   /* Number of iterations if constant.  */
 413   uint64_t niter;
 414
 415   /* Assumptions under that the rest of the information is valid.  */
 416   rtx assumptions;
 417
 418   /* Assumptions under that the loop ends before reaching the latch,
 419      even if value of niter_expr says otherwise.  */
 420   rtx noloop_assumptions;
 421
 422   /* Condition under that the loop is infinite.  */
 423   rtx infinite;
 424
 425   /* Whether the comparison is signed.  */
 426   bool signed_p;
 427
 428   /* The mode in that niter_expr should be computed.  */
 429   enum machine_mode mode;
 430
 431   /* The number of iterations of the loop.  */
 432   rtx niter_expr;
 433 };
 434
 435 extern void iv_analysis_loop_init (struct loop *);
 436 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 437 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 438 extern bool iv_analyze_expr (rtx_insn *, rtx, enum machine_mode,
 439                              struct rtx_iv *);
 440 extern rtx get_iv_value (struct rtx_iv *, rtx);
 441 extern bool biv_p (rtx_insn *, rtx);
 442 extern void find_simple_exit (struct loop *, struct niter_desc *);
 443 extern void iv_analysis_done (void);
 444
 445 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 446 extern void free_simple_loop_desc (struct loop *loop);
 447
 448 static inline struct niter_desc *
 449 simple_loop_desc (struct loop *loop)
 450 {
 451   return loop->simple_loop_desc;
 452 }
 453
 454 /* Accessors for the loop structures.  */
 455
 456 /* Returns the loop with index NUM from FNs loop tree.  */
 457
 458 static inline struct loop *
 459 get_loop (struct function *fn, unsigned num)
 460 {
 461   return (*loops_for_fn (fn)->larray)[num];
 462 }
 463
 464 /* Returns the number of superloops of LOOP.  */
 465
 466 static inline unsigned
 467 loop_depth (const struct loop *loop)
 468 {
 469   return vec_safe_length (loop->superloops);
 470 }
 471
 472 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 473    loop.  */
 474
 475 static inline struct loop *
 476 loop_outer (const struct loop *loop)
 477 {
 478   unsigned n = vec_safe_length (loop->superloops);
 479
 480   if (n == 0)
 481     return NULL;
 482
 483   return (*loop->superloops)[n - 1];
 484 }
 485
 486 /* Returns true if LOOP has at least one exit edge.  */
 487
 488 static inline bool
 489 loop_has_exit_edges (const struct loop *loop)
 490 {
 491   return loop->exits->next->e != NULL;
 492 }
 493
 494 /* Returns the list of loops in FN.  */
 495
 496 inline vec<loop_p, va_gc> *
 497 get_loops (struct function *fn)
 498 {
 499   struct loops *loops = loops_for_fn (fn);
 500   if (!loops)
 501     return NULL;
 502
 503   return loops->larray;
 504 }
 505
 506 /* Returns the number of loops in FN (including the removed
 507    ones and the fake loop that forms the root of the loop tree).  */
 508
 509 static inline unsigned
 510 number_of_loops (struct function *fn)
 511 {
 512   struct loops *loops = loops_for_fn (fn);
 513   if (!loops)
 514     return 0;
 515
 516   return vec_safe_length (loops->larray);
 517 }
 518
 519 /* Returns true if state of the loops satisfies all properties
 520    described by FLAGS.  */
 521
 522 static inline bool
 523 loops_state_satisfies_p (unsigned flags)
 524 {
 525   return (current_loops->state & flags) == flags;
 526 }
 527
 528 /* Sets FLAGS to the loops state.  */
 529
 530 static inline void
 531 loops_state_set (unsigned flags)
 532 {
 533   current_loops->state |= flags;
 534 }
 535
 536 /* Clears FLAGS from the loops state.  */
 537
 538 static inline void
 539 loops_state_clear (unsigned flags)
 540 {
 541   if (!current_loops)
 542     return;
 543   current_loops->state &= ~flags;
 544 }
 545
 546 /* Loop iterators.  */
 547
 548 /* Flags for loop iteration.  */
 549
 550 enum li_flags
 551 {
 552   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 553   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 554                                    starting from innermost ones.  */
 555   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 556 };
 557
 558 /* The iterator for loops.  */
 559
 560 struct loop_iterator
 561 {
 562   loop_iterator (loop_p *loop, unsigned flags);
 563   ~loop_iterator ();
 564
 565   inline loop_p next ();
 566
 567   /* The list of loops to visit.  */
 568   vec<int> to_visit;
 569
 570   /* The index of the actual loop.  */
 571   unsigned idx;
 572 };
 573
 574 inline loop_p
 575 loop_iterator::next ()
 576 {
 577   int anum;
 578
 579   while (this->to_visit.iterate (this->idx, &anum))
 580     {
 581       this->idx++;
 582       loop_p loop = get_loop (cfun, anum);
 583       if (loop)
 584         return loop;
 585     }
 586
 587   return NULL;
 588 }
 589
 590 inline
 591 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 592 {
 593   struct loop *aloop;
 594   unsigned i;
 595   int mn;
 596
 597   this->idx = 0;
 598   if (!current_loops)
 599     {
 600       this->to_visit.create (0);
 601       *loop = NULL;
 602       return;
 603     }
 604
 605   this->to_visit.create (number_of_loops (cfun));
 606   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 607
 608   if (flags & LI_ONLY_INNERMOST)
 609     {
 610       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 611         if (aloop != NULL
 612             && aloop->inner == NULL
 613             && aloop->num >= mn)
 614           this->to_visit.quick_push (aloop->num);
 615     }
 616   else if (flags & LI_FROM_INNERMOST)
 617     {
 618       /* Push the loops to LI->TO_VISIT in postorder.  */
 619       for (aloop = current_loops->tree_root;
 620            aloop->inner != NULL;
 621            aloop = aloop->inner)
 622         continue;
 623
 624       while (1)
 625         {
 626           if (aloop->num >= mn)
 627             this->to_visit.quick_push (aloop->num);
 628
 629           if (aloop->next)
 630             {
 631               for (aloop = aloop->next;
 632                    aloop->inner != NULL;
 633                    aloop = aloop->inner)
 634                 continue;
 635             }
 636           else if (!loop_outer (aloop))
 637             break;
 638           else
 639             aloop = loop_outer (aloop);
 640         }
 641     }
 642   else
 643     {
 644       /* Push the loops to LI->TO_VISIT in preorder.  */
 645       aloop = current_loops->tree_root;
 646       while (1)
 647         {
 648           if (aloop->num >= mn)
 649             this->to_visit.quick_push (aloop->num);
 650
 651           if (aloop->inner != NULL)
 652             aloop = aloop->inner;
 653           else
 654             {
 655               while (aloop != NULL && aloop->next == NULL)
 656                 aloop = loop_outer (aloop);
 657               if (aloop == NULL)
 658                 break;
 659               aloop = aloop->next;
 660             }
 661         }
 662     }
 663
 664   *loop = this->next ();
 665 }
 666
 667 inline
 668 loop_iterator::~loop_iterator ()
 669 {
 670   this->to_visit.release ();
 671 }
 672
 673 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 674   for (loop_iterator li(&(LOOP), FLAGS); \
 675        (LOOP); \
 676        (LOOP) = li.next ())
 677
 678 /* The properties of the target.  */
 679 struct target_cfgloop {
 680   /* Number of available registers.  */
 681   unsigned x_target_avail_regs;
 682
 683   /* Number of available registers that are call-clobbered.  */
 684   unsigned x_target_clobbered_regs;
 685
 686   /* Number of registers reserved for temporary expressions.  */
 687   unsigned x_target_res_regs;
 688
 689   /* The cost for register when there still is some reserve, but we are
 690      approaching the number of available registers.  */
 691   unsigned x_target_reg_cost[2];
 692
 693   /* The cost for register when we need to spill.  */
 694   unsigned x_target_spill_cost[2];
 695 };
 696
 697 extern struct target_cfgloop default_target_cfgloop;
 698 #if SWITCHABLE_TARGET
 699 extern struct target_cfgloop *this_target_cfgloop;
 700 #else
 701 #define this_target_cfgloop (&default_target_cfgloop)
 702 #endif
 703
 704 #define target_avail_regs \
 705   (this_target_cfgloop->x_target_avail_regs)
 706 #define target_clobbered_regs \
 707   (this_target_cfgloop->x_target_clobbered_regs)
 708 #define target_res_regs \
 709   (this_target_cfgloop->x_target_res_regs)
 710 #define target_reg_cost \
 711   (this_target_cfgloop->x_target_reg_cost)
 712 #define target_spill_cost \
 713   (this_target_cfgloop->x_target_spill_cost)
 714
 715 /* Register pressure estimation for induction variable optimizations & loop
 716    invariant motion.  */
 717 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 718 extern void init_set_costs (void);
 719
 720 /* Loop optimizer initialization.  */
 721 extern void loop_optimizer_init (unsigned);
 722 extern void loop_optimizer_finalize (void);
 723
 724 /* Optimization passes.  */
 725 enum
 726 {
 727   UAP_PEEL = 1,         /* Enables loop peeling.  */
 728   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 729   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 730 };
 731
 732 extern void unroll_and_peel_loops (int);
 733 extern void doloop_optimize_loops (void);
 734 extern void move_loop_invariants (void);
 735 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 736 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 737
 738 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 739 static inline struct loop *
 740 loop_outermost (struct loop *loop)
 741 {
 742   unsigned n = vec_safe_length (loop->superloops);
 743
 744   if (n <= 1)
 745     return loop;
 746
 747   return (*loop->superloops)[1];
 748 }
 749
 750 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 751 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 752 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 753 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 754 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 755 extern int bb_loop_depth (const_basic_block);
 756
 757 /* Converts VAL to widest_int.  */
 758
 759 static inline widest_int
 760 gcov_type_to_wide_int (gcov_type val)
 761 {
 762   HOST_WIDE_INT a[2];
 763
 764   a[0] = (unsigned HOST_WIDE_INT) val;
 765   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 766      the size of type.  */
 767   val >>= HOST_BITS_PER_WIDE_INT - 1;
 768   val >>= 1;
 769   a[1] = (unsigned HOST_WIDE_INT) val;
 770
 771   return widest_int::from_array (a, 2);
 772 }
 773 #endif /* GCC_CFGLOOP_H */