gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987-2013 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 "basic-block.h"
  24 #include "double-int.h"
  25
  26 #include "bitmap.h"
  27 #include "sbitmap.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   double_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 };
 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   /* Upper bound on number of iterations of a loop.  */
 171   struct nb_iter_bound *bounds;
 172
 173   /* Head of the cyclic list of the exits of the loop.  */
 174   struct loop_exit *exits;
 175
 176   /* Number of iteration analysis data for RTL.  */
 177   struct niter_desc *simple_loop_desc;
 178 };
 179
 180 /* Flags for state of loop structure.  */
 181 enum
 182 {
 183   LOOPS_HAVE_PREHEADERS = 1,
 184   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 185   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 186   LOOPS_HAVE_RECORDED_EXITS = 8,
 187   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 188   LOOP_CLOSED_SSA = 32,
 189   LOOPS_NEED_FIXUP = 64,
 190   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 191 };
 192
 193 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 194                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 195 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 196
 197 /* Structure to hold CFG information about natural loops within a function.  */
 198 struct GTY (()) loops {
 199   /* State of loops.  */
 200   int state;
 201
 202   /* Array of the loops.  */
 203   vec<loop_p, va_gc> *larray;
 204
 205   /* Maps edges to the list of their descriptions as loop exits.  Edges
 206      whose sources or destinations have loop_father == NULL (which may
 207      happen during the cfg manipulations) should not appear in EXITS.  */
 208   htab_t GTY((param_is (struct loop_exit))) exits;
 209
 210   /* Pointer to root of loop hierarchy tree.  */
 211   struct loop *tree_root;
 212 };
 213
 214 /* Loop recognition.  */
 215 bool bb_loop_header_p (basic_block);
 216 extern struct loops *flow_loops_find (struct loops *);
 217 extern void disambiguate_loops_with_multiple_latches (void);
 218 extern void flow_loops_free (struct loops *);
 219 extern void flow_loops_dump (FILE *,
 220                              void (*)(const struct loop *, FILE *, int), int);
 221 extern void flow_loop_dump (const struct loop *, FILE *,
 222                             void (*)(const struct loop *, FILE *, int), int);
 223 struct loop *alloc_loop (void);
 224 extern void flow_loop_free (struct loop *);
 225 int flow_loop_nodes_find (basic_block, struct loop *);
 226 unsigned fix_loop_structure (bitmap changed_bbs);
 227 bool mark_irreducible_loops (void);
 228 void release_recorded_exits (void);
 229 void record_loop_exits (void);
 230 void rescan_loop_exit (edge, bool, bool);
 231
 232 /* Loop data structure manipulation/querying.  */
 233 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 234 extern void flow_loop_tree_node_remove (struct loop *);
 235 extern void place_new_loop (struct loop *);
 236 extern void add_loop (struct loop *, struct loop *);
 237 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 238 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 239 extern struct loop * find_common_loop (struct loop *, struct loop *);
 240 struct loop *superloop_at_depth (struct loop *, unsigned);
 241 struct eni_weights_d;
 242 extern unsigned tree_num_loop_insns (struct loop *, struct eni_weights_d *);
 243 extern int num_loop_insns (const struct loop *);
 244 extern int average_num_loop_insns (const struct loop *);
 245 extern unsigned get_loop_level (const struct loop *);
 246 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 247 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 248 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 249 extern void mark_loop_exit_edges (void);
 250 extern location_t get_loop_location (struct loop *loop);
 251
 252 /* Loops & cfg manipulation.  */
 253 extern basic_block *get_loop_body (const struct loop *);
 254 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 255                                          unsigned);
 256 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 257 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 258 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 259                                int (*) (const void *, const void *));
 260
 261 extern vec<edge> get_loop_exit_edges (const struct loop *);
 262 extern edge single_exit (const struct loop *);
 263 extern edge single_likely_exit (struct loop *loop);
 264 extern unsigned num_loop_branches (const struct loop *);
 265
 266 extern edge loop_preheader_edge (const struct loop *);
 267 extern edge loop_latch_edge (const struct loop *);
 268
 269 extern void add_bb_to_loop (basic_block, struct loop *);
 270 extern void remove_bb_from_loops (basic_block);
 271
 272 extern void cancel_loop_tree (struct loop *);
 273 extern void delete_loop (struct loop *);
 274
 275 enum
 276 {
 277   CP_SIMPLE_PREHEADERS = 1,
 278   CP_FALLTHRU_PREHEADERS = 2
 279 };
 280
 281 basic_block create_preheader (struct loop *, int);
 282 extern void create_preheaders (int);
 283 extern void force_single_succ_latches (void);
 284
 285 extern void verify_loop_structure (void);
 286
 287 /* Loop analysis.  */
 288 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 289 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 290 extern unsigned expected_loop_iterations (const struct loop *);
 291 extern rtx doloop_condition_get (rtx);
 292
 293 void estimate_numbers_of_iterations_loop (struct loop *);
 294 void record_niter_bound (struct loop *, double_int, bool, bool);
 295 bool estimated_loop_iterations (struct loop *, double_int *);
 296 bool max_loop_iterations (struct loop *, double_int *);
 297 HOST_WIDE_INT estimated_loop_iterations_int (struct loop *);
 298 HOST_WIDE_INT max_loop_iterations_int (struct loop *);
 299 bool max_stmt_executions (struct loop *, double_int *);
 300 bool estimated_stmt_executions (struct loop *, double_int *);
 301 HOST_WIDE_INT max_stmt_executions_int (struct loop *);
 302 HOST_WIDE_INT estimated_stmt_executions_int (struct loop *);
 303
 304 /* Loop manipulation.  */
 305 extern bool can_duplicate_loop_p (const struct loop *loop);
 306
 307 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 308                                            duplicate_loop_to_header_edge.  */
 309 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 310                                            field of newly create BB.  */
 311 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 312                                            a complete peeling.  */
 313
 314 extern edge create_empty_if_region_on_edge (edge, tree);
 315 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 316                                                tree *, tree *, struct loop *);
 317 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 318 extern void copy_loop_info (struct loop *loop, struct loop *target);
 319 extern void duplicate_subloops (struct loop *, struct loop *);
 320 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 321                                            unsigned, sbitmap, edge,
 322                                            vec<edge> *, int);
 323 extern struct loop *loopify (edge, edge,
 324                              basic_block, edge, edge, bool,
 325                              unsigned, unsigned);
 326 struct loop * loop_version (struct loop *, void *,
 327                             basic_block *, unsigned, unsigned, unsigned, bool);
 328 extern bool remove_path (edge);
 329 extern void unloop (struct loop *, bool *, bitmap);
 330 extern void scale_loop_frequencies (struct loop *, int, int);
 331
 332 /* Induction variable analysis.  */
 333
 334 /* The description of induction variable.  The things are a bit complicated
 335    due to need to handle subregs and extends.  The value of the object described
 336    by it can be obtained as follows (all computations are done in extend_mode):
 337
 338    Value in i-th iteration is
 339      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 340
 341    If first_special is true, the value in the first iteration is
 342      delta + mult * base
 343
 344    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 345      subreg_{mode} (base + i * step)
 346
 347    The get_iv_value function can be used to obtain these expressions.
 348
 349    ??? Add a third mode field that would specify the mode in that inner
 350    computation is done, which would enable it to be different from the
 351    outer one?  */
 352
 353 struct rtx_iv
 354 {
 355   /* Its base and step (mode of base and step is supposed to be extend_mode,
 356      see the description above).  */
 357   rtx base, step;
 358
 359   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 360      or IV_UNKNOWN_EXTEND).  */
 361   enum iv_extend_code extend;
 362
 363   /* Operations applied in the extended mode.  */
 364   rtx delta, mult;
 365
 366   /* The mode it is extended to.  */
 367   enum machine_mode extend_mode;
 368
 369   /* The mode the variable iterates in.  */
 370   enum machine_mode mode;
 371
 372   /* Whether the first iteration needs to be handled specially.  */
 373   unsigned first_special : 1;
 374 };
 375
 376 /* The description of an exit from the loop and of the number of iterations
 377    till we take the exit.  */
 378
 379 struct GTY(()) niter_desc
 380 {
 381   /* The edge out of the loop.  */
 382   edge out_edge;
 383
 384   /* The other edge leading from the condition.  */
 385   edge in_edge;
 386
 387   /* True if we are able to say anything about number of iterations of the
 388      loop.  */
 389   bool simple_p;
 390
 391   /* True if the loop iterates the constant number of times.  */
 392   bool const_iter;
 393
 394   /* Number of iterations if constant.  */
 395   unsigned HOST_WIDEST_INT niter;
 396
 397   /* Assumptions under that the rest of the information is valid.  */
 398   rtx assumptions;
 399
 400   /* Assumptions under that the loop ends before reaching the latch,
 401      even if value of niter_expr says otherwise.  */
 402   rtx noloop_assumptions;
 403
 404   /* Condition under that the loop is infinite.  */
 405   rtx infinite;
 406
 407   /* Whether the comparison is signed.  */
 408   bool signed_p;
 409
 410   /* The mode in that niter_expr should be computed.  */
 411   enum machine_mode mode;
 412
 413   /* The number of iterations of the loop.  */
 414   rtx niter_expr;
 415 };
 416
 417 extern void iv_analysis_loop_init (struct loop *);
 418 extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
 419 extern bool iv_analyze_result (rtx, rtx, struct rtx_iv *);
 420 extern bool iv_analyze_expr (rtx, rtx, enum machine_mode, struct rtx_iv *);
 421 extern rtx get_iv_value (struct rtx_iv *, rtx);
 422 extern bool biv_p (rtx, rtx);
 423 extern void find_simple_exit (struct loop *, struct niter_desc *);
 424 extern void iv_analysis_done (void);
 425
 426 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 427 extern void free_simple_loop_desc (struct loop *loop);
 428
 429 static inline struct niter_desc *
 430 simple_loop_desc (struct loop *loop)
 431 {
 432   return loop->simple_loop_desc;
 433 }
 434
 435 /* Accessors for the loop structures.  */
 436
 437 /* Returns the loop with index NUM from current_loops.  */
 438
 439 static inline struct loop *
 440 get_loop (unsigned num)
 441 {
 442   return (*current_loops->larray)[num];
 443 }
 444
 445 /* Returns the number of superloops of LOOP.  */
 446
 447 static inline unsigned
 448 loop_depth (const struct loop *loop)
 449 {
 450   return vec_safe_length (loop->superloops);
 451 }
 452
 453 /* Returns the loop depth of the loop BB belongs to.  */
 454
 455 static inline int
 456 bb_loop_depth (const_basic_block bb)
 457 {
 458   return bb->loop_father ? loop_depth (bb->loop_father) : 0;
 459 }
 460
 461 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 462    loop.  */
 463
 464 static inline struct loop *
 465 loop_outer (const struct loop *loop)
 466 {
 467   unsigned n = vec_safe_length (loop->superloops);
 468
 469   if (n == 0)
 470     return NULL;
 471
 472   return (*loop->superloops)[n - 1];
 473 }
 474
 475 /* Returns true if LOOP has at least one exit edge.  */
 476
 477 static inline bool
 478 loop_has_exit_edges (const struct loop *loop)
 479 {
 480   return loop->exits->next->e != NULL;
 481 }
 482
 483 /* Returns the list of loops in current_loops.  */
 484
 485 static inline vec<loop_p, va_gc> *
 486 get_loops (void)
 487 {
 488   if (!current_loops)
 489     return NULL;
 490
 491   return current_loops->larray;
 492 }
 493
 494 /* Returns the number of loops in current_loops (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 (void)
 499 {
 500   if (!current_loops)
 501     return 0;
 502
 503   return vec_safe_length (current_loops->larray);
 504 }
 505
 506 /* Returns true if state of the loops satisfies all properties
 507    described by FLAGS.  */
 508
 509 static inline bool
 510 loops_state_satisfies_p (unsigned flags)
 511 {
 512   return (current_loops->state & flags) == flags;
 513 }
 514
 515 /* Sets FLAGS to the loops state.  */
 516
 517 static inline void
 518 loops_state_set (unsigned flags)
 519 {
 520   current_loops->state |= flags;
 521 }
 522
 523 /* Clears FLAGS from the loops state.  */
 524
 525 static inline void
 526 loops_state_clear (unsigned flags)
 527 {
 528   if (!current_loops)
 529     return;
 530   current_loops->state &= ~flags;
 531 }
 532
 533 /* Loop iterators.  */
 534
 535 /* Flags for loop iteration.  */
 536
 537 enum li_flags
 538 {
 539   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 540   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 541                                    starting from innermost ones.  */
 542   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 543 };
 544
 545 /* The iterator for loops.  */
 546
 547 typedef struct
 548 {
 549   /* The list of loops to visit.  */
 550   vec<int> to_visit;
 551
 552   /* The index of the actual loop.  */
 553   unsigned idx;
 554 } loop_iterator;
 555
 556 static inline void
 557 fel_next (loop_iterator *li, loop_p *loop)
 558 {
 559   int anum;
 560
 561   while (li->to_visit.iterate (li->idx, &anum))
 562     {
 563       li->idx++;
 564       *loop = get_loop (anum);
 565       if (*loop)
 566         return;
 567     }
 568
 569   li->to_visit.release ();
 570   *loop = NULL;
 571 }
 572
 573 static inline void
 574 fel_init (loop_iterator *li, loop_p *loop, unsigned flags)
 575 {
 576   struct loop *aloop;
 577   unsigned i;
 578   int mn;
 579
 580   li->idx = 0;
 581   if (!current_loops)
 582     {
 583       li->to_visit.create (0);
 584       *loop = NULL;
 585       return;
 586     }
 587
 588   li->to_visit.create (number_of_loops ());
 589   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 590
 591   if (flags & LI_ONLY_INNERMOST)
 592     {
 593       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 594         if (aloop != NULL
 595             && aloop->inner == NULL
 596             && aloop->num >= mn)
 597           li->to_visit.quick_push (aloop->num);
 598     }
 599   else if (flags & LI_FROM_INNERMOST)
 600     {
 601       /* Push the loops to LI->TO_VISIT in postorder.  */
 602       for (aloop = current_loops->tree_root;
 603            aloop->inner != NULL;
 604            aloop = aloop->inner)
 605         continue;
 606
 607       while (1)
 608         {
 609           if (aloop->num >= mn)
 610             li->to_visit.quick_push (aloop->num);
 611
 612           if (aloop->next)
 613             {
 614               for (aloop = aloop->next;
 615                    aloop->inner != NULL;
 616                    aloop = aloop->inner)
 617                 continue;
 618             }
 619           else if (!loop_outer (aloop))
 620             break;
 621           else
 622             aloop = loop_outer (aloop);
 623         }
 624     }
 625   else
 626     {
 627       /* Push the loops to LI->TO_VISIT in preorder.  */
 628       aloop = current_loops->tree_root;
 629       while (1)
 630         {
 631           if (aloop->num >= mn)
 632             li->to_visit.quick_push (aloop->num);
 633
 634           if (aloop->inner != NULL)
 635             aloop = aloop->inner;
 636           else
 637             {
 638               while (aloop != NULL && aloop->next == NULL)
 639                 aloop = loop_outer (aloop);
 640               if (aloop == NULL)
 641                 break;
 642               aloop = aloop->next;
 643             }
 644         }
 645     }
 646
 647   fel_next (li, loop);
 648 }
 649
 650 #define FOR_EACH_LOOP(LI, LOOP, FLAGS) \
 651   for (fel_init (&(LI), &(LOOP), FLAGS); \
 652        (LOOP); \
 653        fel_next (&(LI), &(LOOP)))
 654
 655 #define FOR_EACH_LOOP_BREAK(LI) \
 656   { \
 657     (LI).to_visit.release (); \
 658     break; \
 659   }
 660
 661 /* The properties of the target.  */
 662 struct target_cfgloop {
 663   /* Number of available registers.  */
 664   unsigned x_target_avail_regs;
 665
 666   /* Number of available registers that are call-clobbered.  */
 667   unsigned x_target_clobbered_regs;
 668
 669   /* Number of registers reserved for temporary expressions.  */
 670   unsigned x_target_res_regs;
 671
 672   /* The cost for register when there still is some reserve, but we are
 673      approaching the number of available registers.  */
 674   unsigned x_target_reg_cost[2];
 675
 676   /* The cost for register when we need to spill.  */
 677   unsigned x_target_spill_cost[2];
 678 };
 679
 680 extern struct target_cfgloop default_target_cfgloop;
 681 #if SWITCHABLE_TARGET
 682 extern struct target_cfgloop *this_target_cfgloop;
 683 #else
 684 #define this_target_cfgloop (&default_target_cfgloop)
 685 #endif
 686
 687 #define target_avail_regs \
 688   (this_target_cfgloop->x_target_avail_regs)
 689 #define target_clobbered_regs \
 690   (this_target_cfgloop->x_target_clobbered_regs)
 691 #define target_res_regs \
 692   (this_target_cfgloop->x_target_res_regs)
 693 #define target_reg_cost \
 694   (this_target_cfgloop->x_target_reg_cost)
 695 #define target_spill_cost \
 696   (this_target_cfgloop->x_target_spill_cost)
 697
 698 /* Register pressure estimation for induction variable optimizations & loop
 699    invariant motion.  */
 700 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 701 extern void init_set_costs (void);
 702
 703 /* Loop optimizer initialization.  */
 704 extern void loop_optimizer_init (unsigned);
 705 extern void loop_optimizer_finalize (void);
 706
 707 /* Optimization passes.  */
 708 extern void unswitch_loops (void);
 709
 710 enum
 711 {
 712   UAP_PEEL = 1,         /* Enables loop peeling.  */
 713   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 714   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 715 };
 716
 717 extern void unroll_and_peel_loops (int);
 718 extern void doloop_optimize_loops (void);
 719 extern void move_loop_invariants (void);
 720 extern bool finite_loop_p (struct loop *);
 721 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 722 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 723
 724 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 725 static inline struct loop *
 726 loop_outermost (struct loop *loop)
 727 {
 728   unsigned n = vec_safe_length (loop->superloops);
 729
 730   if (n <= 1)
 731     return loop;
 732
 733   return (*loop->superloops)[1];
 734 }
 735
 736
 737 #endif /* GCC_CFGLOOP_H */