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 ((for_user)) 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 struct loop_exit_hasher : ggc_hasher<loop_exit *>
  92 {
  93   typedef edge compare_type;
  94
  95   static hashval_t hash (loop_exit *);
  96   static bool equal (loop_exit *, edge);
  97   static void remove (loop_exit *);
  98 };
  99
 100 typedef struct loop *loop_p;
 101
 102 /* An integer estimation of the number of iterations.  Estimate_state
 103    describes what is the state of the estimation.  */
 104 enum loop_estimation
 105 {
 106   /* Estimate was not computed yet.  */
 107   EST_NOT_COMPUTED,
 108   /* Estimate is ready.  */
 109   EST_AVAILABLE,
 110   EST_LAST
 111 };
 112
 113 /* Structure to hold information for each natural loop.  */
 114 struct GTY ((chain_next ("%h.next"))) loop {
 115   /* Index into loops array.  */
 116   int num;
 117
 118   /* Number of loop insns.  */
 119   unsigned ninsns;
 120
 121   /* Basic block of loop header.  */
 122   basic_block header;
 123
 124   /* Basic block of loop latch.  */
 125   basic_block latch;
 126
 127   /* For loop unrolling/peeling decision.  */
 128   struct lpt_decision lpt_decision;
 129
 130   /* Average number of executed insns per iteration.  */
 131   unsigned av_ninsns;
 132
 133   /* Number of blocks contained within the loop.  */
 134   unsigned num_nodes;
 135
 136   /* Superloops of the loop, starting with the outermost loop.  */
 137   vec<loop_p, va_gc> *superloops;
 138
 139   /* The first inner (child) loop or NULL if innermost loop.  */
 140   struct loop *inner;
 141
 142   /* Link to the next (sibling) loop.  */
 143   struct loop *next;
 144
 145   /* Auxiliary info specific to a pass.  */
 146   PTR GTY ((skip (""))) aux;
 147
 148   /* The number of times the latch of the loop is executed.  This can be an
 149      INTEGER_CST, or a symbolic expression representing the number of
 150      iterations like "N - 1", or a COND_EXPR containing the runtime
 151      conditions under which the number of iterations is non zero.
 152
 153      Don't access this field directly: number_of_latch_executions
 154      computes and caches the computed information in this field.  */
 155   tree nb_iterations;
 156
 157   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 158      valid if any_upper_bound is true.  */
 159   widest_int nb_iterations_upper_bound;
 160
 161   /* An integer giving an estimate on nb_iterations.  Unlike
 162      nb_iterations_upper_bound, there is no guarantee that it is at least
 163      nb_iterations.  */
 164   widest_int nb_iterations_estimate;
 165
 166   bool any_upper_bound;
 167   bool any_estimate;
 168
 169   /* True if the loop can be parallel.  */
 170   bool can_be_parallel;
 171
 172   /* True if -Waggressive-loop-optimizations warned about this loop
 173      already.  */
 174   bool warned_aggressive_loop_optimizations;
 175
 176   /* An integer estimation of the number of iterations.  Estimate_state
 177      describes what is the state of the estimation.  */
 178   enum loop_estimation estimate_state;
 179
 180   /* If > 0, an integer, where the user asserted that for any
 181      I in [ 0, nb_iterations ) and for any J in
 182      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 183      of the loop can be safely evaluated concurrently.  */
 184   int safelen;
 185
 186   /* True if this loop should never be vectorized.  */
 187   bool dont_vectorize;
 188
 189   /* True if we should try harder to vectorize this loop.  */
 190   bool force_vectorize;
 191
 192   /* For SIMD loops, this is a unique identifier of the loop, referenced
 193      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 194      builtins.  */
 195   tree simduid;
 196
 197   /* Upper bound on number of iterations of a loop.  */
 198   struct nb_iter_bound *bounds;
 199
 200   /* Head of the cyclic list of the exits of the loop.  */
 201   struct loop_exit *exits;
 202
 203   /* Number of iteration analysis data for RTL.  */
 204   struct niter_desc *simple_loop_desc;
 205
 206   /* For sanity checking during loop fixup we record here the former
 207      loop header for loops marked for removal.  Note that this prevents
 208      the basic-block from being collected but its index can still be
 209      reused.  */
 210   basic_block former_header;
 211 };
 212
 213 /* Flags for state of loop structure.  */
 214 enum
 215 {
 216   LOOPS_HAVE_PREHEADERS = 1,
 217   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 218   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 219   LOOPS_HAVE_RECORDED_EXITS = 8,
 220   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 221   LOOP_CLOSED_SSA = 32,
 222   LOOPS_NEED_FIXUP = 64,
 223   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 224 };
 225
 226 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 227                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 228 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 229
 230 /* Structure to hold CFG information about natural loops within a function.  */
 231 struct GTY (()) loops {
 232   /* State of loops.  */
 233   int state;
 234
 235   /* Array of the loops.  */
 236   vec<loop_p, va_gc> *larray;
 237
 238   /* Maps edges to the list of their descriptions as loop exits.  Edges
 239      whose sources or destinations have loop_father == NULL (which may
 240      happen during the cfg manipulations) should not appear in EXITS.  */
 241   hash_table<loop_exit_hasher> *GTY(()) exits;
 242
 243   /* Pointer to root of loop hierarchy tree.  */
 244   struct loop *tree_root;
 245 };
 246
 247 /* Loop recognition.  */
 248 bool bb_loop_header_p (basic_block);
 249 void init_loops_structure (struct function *, struct loops *, unsigned);
 250 extern struct loops *flow_loops_find (struct loops *);
 251 extern void disambiguate_loops_with_multiple_latches (void);
 252 extern void flow_loops_free (struct loops *);
 253 extern void flow_loops_dump (FILE *,
 254                              void (*)(const struct loop *, FILE *, int), int);
 255 extern void flow_loop_dump (const struct loop *, FILE *,
 256                             void (*)(const struct loop *, FILE *, int), int);
 257 struct loop *alloc_loop (void);
 258 extern void flow_loop_free (struct loop *);
 259 int flow_loop_nodes_find (basic_block, struct loop *);
 260 unsigned fix_loop_structure (bitmap changed_bbs);
 261 bool mark_irreducible_loops (void);
 262 void release_recorded_exits (void);
 263 void record_loop_exits (void);
 264 void rescan_loop_exit (edge, bool, bool);
 265
 266 /* Loop data structure manipulation/querying.  */
 267 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 268 extern void flow_loop_tree_node_remove (struct loop *);
 269 extern void place_new_loop (struct function *, struct loop *);
 270 extern void add_loop (struct loop *, struct loop *);
 271 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 272 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 273 extern struct loop * find_common_loop (struct loop *, struct loop *);
 274 struct loop *superloop_at_depth (struct loop *, unsigned);
 275 struct eni_weights_d;
 276 extern int num_loop_insns (const struct loop *);
 277 extern int average_num_loop_insns (const struct loop *);
 278 extern unsigned get_loop_level (const struct loop *);
 279 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 280 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 281 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 282 extern void mark_loop_exit_edges (void);
 283 extern location_t get_loop_location (struct loop *loop);
 284
 285 /* Loops & cfg manipulation.  */
 286 extern basic_block *get_loop_body (const struct loop *);
 287 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 288                                          unsigned);
 289 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 290 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 291 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 292                                int (*) (const void *, const void *));
 293
 294 extern vec<edge> get_loop_exit_edges (const struct loop *);
 295 extern edge single_exit (const struct loop *);
 296 extern edge single_likely_exit (struct loop *loop);
 297 extern unsigned num_loop_branches (const struct loop *);
 298
 299 extern edge loop_preheader_edge (const struct loop *);
 300 extern edge loop_latch_edge (const struct loop *);
 301
 302 extern void add_bb_to_loop (basic_block, struct loop *);
 303 extern void remove_bb_from_loops (basic_block);
 304
 305 extern void cancel_loop_tree (struct loop *);
 306 extern void delete_loop (struct loop *);
 307
 308 enum
 309 {
 310   CP_SIMPLE_PREHEADERS = 1,
 311   CP_FALLTHRU_PREHEADERS = 2
 312 };
 313
 314 basic_block create_preheader (struct loop *, int);
 315 extern void create_preheaders (int);
 316 extern void force_single_succ_latches (void);
 317
 318 extern void verify_loop_structure (void);
 319
 320 /* Loop analysis.  */
 321 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 322 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 323 extern unsigned expected_loop_iterations (const struct loop *);
 324 extern rtx doloop_condition_get (rtx);
 325
 326
 327 /* Loop manipulation.  */
 328 extern bool can_duplicate_loop_p (const struct loop *loop);
 329
 330 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 331                                            duplicate_loop_to_header_edge.  */
 332 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 333                                            field of newly create BB.  */
 334 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 335                                            a complete peeling.  */
 336
 337 extern edge create_empty_if_region_on_edge (edge, tree);
 338 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 339                                                tree *, tree *, struct loop *);
 340 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 341 extern void copy_loop_info (struct loop *loop, struct loop *target);
 342 extern void duplicate_subloops (struct loop *, struct loop *);
 343 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 344                                            unsigned, sbitmap, edge,
 345                                            vec<edge> *, int);
 346 extern struct loop *loopify (edge, edge,
 347                              basic_block, edge, edge, bool,
 348                              unsigned, unsigned);
 349 struct loop * loop_version (struct loop *, void *,
 350                             basic_block *, unsigned, unsigned, unsigned, bool);
 351 extern bool remove_path (edge);
 352 extern void unloop (struct loop *, bool *, bitmap);
 353 extern void scale_loop_frequencies (struct loop *, int, int);
 354 void mark_loop_for_removal (loop_p);
 355
 356
 357 /* Induction variable analysis.  */
 358
 359 /* The description of induction variable.  The things are a bit complicated
 360    due to need to handle subregs and extends.  The value of the object described
 361    by it can be obtained as follows (all computations are done in extend_mode):
 362
 363    Value in i-th iteration is
 364      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 365
 366    If first_special is true, the value in the first iteration is
 367      delta + mult * base
 368
 369    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 370      subreg_{mode} (base + i * step)
 371
 372    The get_iv_value function can be used to obtain these expressions.
 373
 374    ??? Add a third mode field that would specify the mode in that inner
 375    computation is done, which would enable it to be different from the
 376    outer one?  */
 377
 378 struct rtx_iv
 379 {
 380   /* Its base and step (mode of base and step is supposed to be extend_mode,
 381      see the description above).  */
 382   rtx base, step;
 383
 384   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 385      or IV_UNKNOWN_EXTEND).  */
 386   enum iv_extend_code extend;
 387
 388   /* Operations applied in the extended mode.  */
 389   rtx delta, mult;
 390
 391   /* The mode it is extended to.  */
 392   enum machine_mode extend_mode;
 393
 394   /* The mode the variable iterates in.  */
 395   enum machine_mode mode;
 396
 397   /* Whether the first iteration needs to be handled specially.  */
 398   unsigned first_special : 1;
 399 };
 400
 401 /* The description of an exit from the loop and of the number of iterations
 402    till we take the exit.  */
 403
 404 struct GTY(()) niter_desc
 405 {
 406   /* The edge out of the loop.  */
 407   edge out_edge;
 408
 409   /* The other edge leading from the condition.  */
 410   edge in_edge;
 411
 412   /* True if we are able to say anything about number of iterations of the
 413      loop.  */
 414   bool simple_p;
 415
 416   /* True if the loop iterates the constant number of times.  */
 417   bool const_iter;
 418
 419   /* Number of iterations if constant.  */
 420   uint64_t niter;
 421
 422   /* Assumptions under that the rest of the information is valid.  */
 423   rtx assumptions;
 424
 425   /* Assumptions under that the loop ends before reaching the latch,
 426      even if value of niter_expr says otherwise.  */
 427   rtx noloop_assumptions;
 428
 429   /* Condition under that the loop is infinite.  */
 430   rtx infinite;
 431
 432   /* Whether the comparison is signed.  */
 433   bool signed_p;
 434
 435   /* The mode in that niter_expr should be computed.  */
 436   enum machine_mode mode;
 437
 438   /* The number of iterations of the loop.  */
 439   rtx niter_expr;
 440 };
 441
 442 extern void iv_analysis_loop_init (struct loop *);
 443 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 444 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 445 extern bool iv_analyze_expr (rtx_insn *, rtx, enum machine_mode,
 446                              struct rtx_iv *);
 447 extern rtx get_iv_value (struct rtx_iv *, rtx);
 448 extern bool biv_p (rtx_insn *, rtx);
 449 extern void find_simple_exit (struct loop *, struct niter_desc *);
 450 extern void iv_analysis_done (void);
 451
 452 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 453 extern void free_simple_loop_desc (struct loop *loop);
 454
 455 static inline struct niter_desc *
 456 simple_loop_desc (struct loop *loop)
 457 {
 458   return loop->simple_loop_desc;
 459 }
 460
 461 /* Accessors for the loop structures.  */
 462
 463 /* Returns the loop with index NUM from FNs loop tree.  */
 464
 465 static inline struct loop *
 466 get_loop (struct function *fn, unsigned num)
 467 {
 468   return (*loops_for_fn (fn)->larray)[num];
 469 }
 470
 471 /* Returns the number of superloops of LOOP.  */
 472
 473 static inline unsigned
 474 loop_depth (const struct loop *loop)
 475 {
 476   return vec_safe_length (loop->superloops);
 477 }
 478
 479 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 480    loop.  */
 481
 482 static inline struct loop *
 483 loop_outer (const struct loop *loop)
 484 {
 485   unsigned n = vec_safe_length (loop->superloops);
 486
 487   if (n == 0)
 488     return NULL;
 489
 490   return (*loop->superloops)[n - 1];
 491 }
 492
 493 /* Returns true if LOOP has at least one exit edge.  */
 494
 495 static inline bool
 496 loop_has_exit_edges (const struct loop *loop)
 497 {
 498   return loop->exits->next->e != NULL;
 499 }
 500
 501 /* Returns the list of loops in FN.  */
 502
 503 inline vec<loop_p, va_gc> *
 504 get_loops (struct function *fn)
 505 {
 506   struct loops *loops = loops_for_fn (fn);
 507   if (!loops)
 508     return NULL;
 509
 510   return loops->larray;
 511 }
 512
 513 /* Returns the number of loops in FN (including the removed
 514    ones and the fake loop that forms the root of the loop tree).  */
 515
 516 static inline unsigned
 517 number_of_loops (struct function *fn)
 518 {
 519   struct loops *loops = loops_for_fn (fn);
 520   if (!loops)
 521     return 0;
 522
 523   return vec_safe_length (loops->larray);
 524 }
 525
 526 /* Returns true if state of the loops satisfies all properties
 527    described by FLAGS.  */
 528
 529 static inline bool
 530 loops_state_satisfies_p (unsigned flags)
 531 {
 532   return (current_loops->state & flags) == flags;
 533 }
 534
 535 /* Sets FLAGS to the loops state.  */
 536
 537 static inline void
 538 loops_state_set (unsigned flags)
 539 {
 540   current_loops->state |= flags;
 541 }
 542
 543 /* Clears FLAGS from the loops state.  */
 544
 545 static inline void
 546 loops_state_clear (unsigned flags)
 547 {
 548   if (!current_loops)
 549     return;
 550   current_loops->state &= ~flags;
 551 }
 552
 553 /* Loop iterators.  */
 554
 555 /* Flags for loop iteration.  */
 556
 557 enum li_flags
 558 {
 559   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 560   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 561                                    starting from innermost ones.  */
 562   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 563 };
 564
 565 /* The iterator for loops.  */
 566
 567 struct loop_iterator
 568 {
 569   loop_iterator (loop_p *loop, unsigned flags);
 570   ~loop_iterator ();
 571
 572   inline loop_p next ();
 573
 574   /* The list of loops to visit.  */
 575   vec<int> to_visit;
 576
 577   /* The index of the actual loop.  */
 578   unsigned idx;
 579 };
 580
 581 inline loop_p
 582 loop_iterator::next ()
 583 {
 584   int anum;
 585
 586   while (this->to_visit.iterate (this->idx, &anum))
 587     {
 588       this->idx++;
 589       loop_p loop = get_loop (cfun, anum);
 590       if (loop)
 591         return loop;
 592     }
 593
 594   return NULL;
 595 }
 596
 597 inline
 598 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 599 {
 600   struct loop *aloop;
 601   unsigned i;
 602   int mn;
 603
 604   this->idx = 0;
 605   if (!current_loops)
 606     {
 607       this->to_visit.create (0);
 608       *loop = NULL;
 609       return;
 610     }
 611
 612   this->to_visit.create (number_of_loops (cfun));
 613   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 614
 615   if (flags & LI_ONLY_INNERMOST)
 616     {
 617       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 618         if (aloop != NULL
 619             && aloop->inner == NULL
 620             && aloop->num >= mn)
 621           this->to_visit.quick_push (aloop->num);
 622     }
 623   else if (flags & LI_FROM_INNERMOST)
 624     {
 625       /* Push the loops to LI->TO_VISIT in postorder.  */
 626       for (aloop = current_loops->tree_root;
 627            aloop->inner != NULL;
 628            aloop = aloop->inner)
 629         continue;
 630
 631       while (1)
 632         {
 633           if (aloop->num >= mn)
 634             this->to_visit.quick_push (aloop->num);
 635
 636           if (aloop->next)
 637             {
 638               for (aloop = aloop->next;
 639                    aloop->inner != NULL;
 640                    aloop = aloop->inner)
 641                 continue;
 642             }
 643           else if (!loop_outer (aloop))
 644             break;
 645           else
 646             aloop = loop_outer (aloop);
 647         }
 648     }
 649   else
 650     {
 651       /* Push the loops to LI->TO_VISIT in preorder.  */
 652       aloop = current_loops->tree_root;
 653       while (1)
 654         {
 655           if (aloop->num >= mn)
 656             this->to_visit.quick_push (aloop->num);
 657
 658           if (aloop->inner != NULL)
 659             aloop = aloop->inner;
 660           else
 661             {
 662               while (aloop != NULL && aloop->next == NULL)
 663                 aloop = loop_outer (aloop);
 664               if (aloop == NULL)
 665                 break;
 666               aloop = aloop->next;
 667             }
 668         }
 669     }
 670
 671   *loop = this->next ();
 672 }
 673
 674 inline
 675 loop_iterator::~loop_iterator ()
 676 {
 677   this->to_visit.release ();
 678 }
 679
 680 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 681   for (loop_iterator li(&(LOOP), FLAGS); \
 682        (LOOP); \
 683        (LOOP) = li.next ())
 684
 685 /* The properties of the target.  */
 686 struct target_cfgloop {
 687   /* Number of available registers.  */
 688   unsigned x_target_avail_regs;
 689
 690   /* Number of available registers that are call-clobbered.  */
 691   unsigned x_target_clobbered_regs;
 692
 693   /* Number of registers reserved for temporary expressions.  */
 694   unsigned x_target_res_regs;
 695
 696   /* The cost for register when there still is some reserve, but we are
 697      approaching the number of available registers.  */
 698   unsigned x_target_reg_cost[2];
 699
 700   /* The cost for register when we need to spill.  */
 701   unsigned x_target_spill_cost[2];
 702 };
 703
 704 extern struct target_cfgloop default_target_cfgloop;
 705 #if SWITCHABLE_TARGET
 706 extern struct target_cfgloop *this_target_cfgloop;
 707 #else
 708 #define this_target_cfgloop (&default_target_cfgloop)
 709 #endif
 710
 711 #define target_avail_regs \
 712   (this_target_cfgloop->x_target_avail_regs)
 713 #define target_clobbered_regs \
 714   (this_target_cfgloop->x_target_clobbered_regs)
 715 #define target_res_regs \
 716   (this_target_cfgloop->x_target_res_regs)
 717 #define target_reg_cost \
 718   (this_target_cfgloop->x_target_reg_cost)
 719 #define target_spill_cost \
 720   (this_target_cfgloop->x_target_spill_cost)
 721
 722 /* Register pressure estimation for induction variable optimizations & loop
 723    invariant motion.  */
 724 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 725 extern void init_set_costs (void);
 726
 727 /* Loop optimizer initialization.  */
 728 extern void loop_optimizer_init (unsigned);
 729 extern void loop_optimizer_finalize (void);
 730
 731 /* Optimization passes.  */
 732 enum
 733 {
 734   UAP_PEEL = 1,         /* Enables loop peeling.  */
 735   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 736   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 737 };
 738
 739 extern void unroll_and_peel_loops (int);
 740 extern void doloop_optimize_loops (void);
 741 extern void move_loop_invariants (void);
 742 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 743 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 744
 745 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 746 static inline struct loop *
 747 loop_outermost (struct loop *loop)
 748 {
 749   unsigned n = vec_safe_length (loop->superloops);
 750
 751   if (n <= 1)
 752     return loop;
 753
 754   return (*loop->superloops)[1];
 755 }
 756
 757 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 758 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 759 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 760 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 761 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 762 extern int bb_loop_depth (const_basic_block);
 763
 764 /* Converts VAL to widest_int.  */
 765
 766 static inline widest_int
 767 gcov_type_to_wide_int (gcov_type val)
 768 {
 769   HOST_WIDE_INT a[2];
 770
 771   a[0] = (unsigned HOST_WIDE_INT) val;
 772   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 773      the size of type.  */
 774   val >>= HOST_BITS_PER_WIDE_INT - 1;
 775   val >>= 1;
 776   a[1] = (unsigned HOST_WIDE_INT) val;
 777
 778   return widest_int::from_array (a, 2);
 779 }
 780 #endif /* GCC_CFGLOOP_H */