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   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   double_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   double_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   /* Upper bound on number of iterations of a loop.  */
 172   struct nb_iter_bound *bounds;
 173
 174   /* Head of the cyclic list of the exits of the loop.  */
 175   struct loop_exit *exits;
 176
 177   /* Number of iteration analysis data for RTL.  */
 178   struct niter_desc *simple_loop_desc;
 179 };
 180
 181 /* Flags for state of loop structure.  */
 182 enum
 183 {
 184   LOOPS_HAVE_PREHEADERS = 1,
 185   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 186   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 187   LOOPS_HAVE_RECORDED_EXITS = 8,
 188   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 189   LOOP_CLOSED_SSA = 32,
 190   LOOPS_NEED_FIXUP = 64,
 191   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 192 };
 193
 194 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 195                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 196 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 197
 198 /* Structure to hold CFG information about natural loops within a function.  */
 199 struct GTY (()) loops {
 200   /* State of loops.  */
 201   int state;
 202
 203   /* Array of the loops.  */
 204   vec<loop_p, va_gc> *larray;
 205
 206   /* Maps edges to the list of their descriptions as loop exits.  Edges
 207      whose sources or destinations have loop_father == NULL (which may
 208      happen during the cfg manipulations) should not appear in EXITS.  */
 209   htab_t GTY((param_is (struct loop_exit))) exits;
 210
 211   /* Pointer to root of loop hierarchy tree.  */
 212   struct loop *tree_root;
 213 };
 214
 215 /* Loop recognition.  */
 216 bool bb_loop_header_p (basic_block);
 217 void init_loops_structure (struct function *, struct loops *, unsigned);
 218 extern struct loops *flow_loops_find (struct loops *);
 219 extern void disambiguate_loops_with_multiple_latches (void);
 220 extern void flow_loops_free (struct loops *);
 221 extern void flow_loops_dump (FILE *,
 222                              void (*)(const struct loop *, FILE *, int), int);
 223 extern void flow_loop_dump (const struct loop *, FILE *,
 224                             void (*)(const struct loop *, FILE *, int), int);
 225 struct loop *alloc_loop (void);
 226 extern void flow_loop_free (struct loop *);
 227 int flow_loop_nodes_find (basic_block, struct loop *);
 228 unsigned fix_loop_structure (bitmap changed_bbs);
 229 bool mark_irreducible_loops (void);
 230 void release_recorded_exits (void);
 231 void record_loop_exits (void);
 232 void rescan_loop_exit (edge, bool, bool);
 233
 234 /* Loop data structure manipulation/querying.  */
 235 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 236 extern void flow_loop_tree_node_remove (struct loop *);
 237 extern void place_new_loop (struct loop *);
 238 extern void add_loop (struct loop *, struct loop *);
 239 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 240 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 241 extern struct loop * find_common_loop (struct loop *, struct loop *);
 242 struct loop *superloop_at_depth (struct loop *, unsigned);
 243 struct eni_weights_d;
 244 extern unsigned tree_num_loop_insns (struct loop *, struct eni_weights_d *);
 245 extern int num_loop_insns (const struct loop *);
 246 extern int average_num_loop_insns (const struct loop *);
 247 extern unsigned get_loop_level (const struct loop *);
 248 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 249 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 250 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 251 extern void mark_loop_exit_edges (void);
 252 extern location_t get_loop_location (struct loop *loop);
 253
 254 /* Loops & cfg manipulation.  */
 255 extern basic_block *get_loop_body (const struct loop *);
 256 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 257                                          unsigned);
 258 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 259 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 260 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 261                                int (*) (const void *, const void *));
 262
 263 extern vec<edge> get_loop_exit_edges (const struct loop *);
 264 extern edge single_exit (const struct loop *);
 265 extern edge single_likely_exit (struct loop *loop);
 266 extern unsigned num_loop_branches (const struct loop *);
 267
 268 extern edge loop_preheader_edge (const struct loop *);
 269 extern edge loop_latch_edge (const struct loop *);
 270
 271 extern void add_bb_to_loop (basic_block, struct loop *);
 272 extern void remove_bb_from_loops (basic_block);
 273
 274 extern void cancel_loop_tree (struct loop *);
 275 extern void delete_loop (struct loop *);
 276
 277 enum
 278 {
 279   CP_SIMPLE_PREHEADERS = 1,
 280   CP_FALLTHRU_PREHEADERS = 2
 281 };
 282
 283 basic_block create_preheader (struct loop *, int);
 284 extern void create_preheaders (int);
 285 extern void force_single_succ_latches (void);
 286
 287 extern void verify_loop_structure (void);
 288
 289 /* Loop analysis.  */
 290 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 291 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 292 extern unsigned expected_loop_iterations (const struct loop *);
 293 extern rtx doloop_condition_get (rtx);
 294
 295 void estimate_numbers_of_iterations_loop (struct loop *);
 296 void record_niter_bound (struct loop *, double_int, bool, bool);
 297 bool estimated_loop_iterations (struct loop *, double_int *);
 298 bool max_loop_iterations (struct loop *, double_int *);
 299 HOST_WIDE_INT estimated_loop_iterations_int (struct loop *);
 300 HOST_WIDE_INT max_loop_iterations_int (struct loop *);
 301 bool max_stmt_executions (struct loop *, double_int *);
 302 bool estimated_stmt_executions (struct loop *, double_int *);
 303 HOST_WIDE_INT max_stmt_executions_int (struct loop *);
 304 HOST_WIDE_INT estimated_stmt_executions_int (struct loop *);
 305
 306 /* Loop manipulation.  */
 307 extern bool can_duplicate_loop_p (const struct loop *loop);
 308
 309 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 310                                            duplicate_loop_to_header_edge.  */
 311 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 312                                            field of newly create BB.  */
 313 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 314                                            a complete peeling.  */
 315
 316 extern edge create_empty_if_region_on_edge (edge, tree);
 317 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 318                                                tree *, tree *, struct loop *);
 319 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 320 extern void copy_loop_info (struct loop *loop, struct loop *target);
 321 extern void duplicate_subloops (struct loop *, struct loop *);
 322 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 323                                            unsigned, sbitmap, edge,
 324                                            vec<edge> *, int);
 325 extern struct loop *loopify (edge, edge,
 326                              basic_block, edge, edge, bool,
 327                              unsigned, unsigned);
 328 struct loop * loop_version (struct loop *, void *,
 329                             basic_block *, unsigned, unsigned, unsigned, bool);
 330 extern bool remove_path (edge);
 331 extern void unloop (struct loop *, bool *, bitmap);
 332 extern void scale_loop_frequencies (struct loop *, int, int);
 333
 334 /* Induction variable analysis.  */
 335
 336 /* The description of induction variable.  The things are a bit complicated
 337    due to need to handle subregs and extends.  The value of the object described
 338    by it can be obtained as follows (all computations are done in extend_mode):
 339
 340    Value in i-th iteration is
 341      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 342
 343    If first_special is true, the value in the first iteration is
 344      delta + mult * base
 345
 346    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 347      subreg_{mode} (base + i * step)
 348
 349    The get_iv_value function can be used to obtain these expressions.
 350
 351    ??? Add a third mode field that would specify the mode in that inner
 352    computation is done, which would enable it to be different from the
 353    outer one?  */
 354
 355 struct rtx_iv
 356 {
 357   /* Its base and step (mode of base and step is supposed to be extend_mode,
 358      see the description above).  */
 359   rtx base, step;
 360
 361   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 362      or IV_UNKNOWN_EXTEND).  */
 363   enum iv_extend_code extend;
 364
 365   /* Operations applied in the extended mode.  */
 366   rtx delta, mult;
 367
 368   /* The mode it is extended to.  */
 369   enum machine_mode extend_mode;
 370
 371   /* The mode the variable iterates in.  */
 372   enum machine_mode mode;
 373
 374   /* Whether the first iteration needs to be handled specially.  */
 375   unsigned first_special : 1;
 376 };
 377
 378 /* The description of an exit from the loop and of the number of iterations
 379    till we take the exit.  */
 380
 381 struct GTY(()) niter_desc
 382 {
 383   /* The edge out of the loop.  */
 384   edge out_edge;
 385
 386   /* The other edge leading from the condition.  */
 387   edge in_edge;
 388
 389   /* True if we are able to say anything about number of iterations of the
 390      loop.  */
 391   bool simple_p;
 392
 393   /* True if the loop iterates the constant number of times.  */
 394   bool const_iter;
 395
 396   /* Number of iterations if constant.  */
 397   unsigned HOST_WIDEST_INT niter;
 398
 399   /* Assumptions under that the rest of the information is valid.  */
 400   rtx assumptions;
 401
 402   /* Assumptions under that the loop ends before reaching the latch,
 403      even if value of niter_expr says otherwise.  */
 404   rtx noloop_assumptions;
 405
 406   /* Condition under that the loop is infinite.  */
 407   rtx infinite;
 408
 409   /* Whether the comparison is signed.  */
 410   bool signed_p;
 411
 412   /* The mode in that niter_expr should be computed.  */
 413   enum machine_mode mode;
 414
 415   /* The number of iterations of the loop.  */
 416   rtx niter_expr;
 417 };
 418
 419 extern void iv_analysis_loop_init (struct loop *);
 420 extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
 421 extern bool iv_analyze_result (rtx, rtx, struct rtx_iv *);
 422 extern bool iv_analyze_expr (rtx, rtx, enum machine_mode, struct rtx_iv *);
 423 extern rtx get_iv_value (struct rtx_iv *, rtx);
 424 extern bool biv_p (rtx, rtx);
 425 extern void find_simple_exit (struct loop *, struct niter_desc *);
 426 extern void iv_analysis_done (void);
 427
 428 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 429 extern void free_simple_loop_desc (struct loop *loop);
 430
 431 static inline struct niter_desc *
 432 simple_loop_desc (struct loop *loop)
 433 {
 434   return loop->simple_loop_desc;
 435 }
 436
 437 /* Accessors for the loop structures.  */
 438
 439 /* Returns the loop with index NUM from current_loops.  */
 440
 441 static inline struct loop *
 442 get_loop (unsigned num)
 443 {
 444   return (*current_loops->larray)[num];
 445 }
 446
 447 /* Returns the number of superloops of LOOP.  */
 448
 449 static inline unsigned
 450 loop_depth (const struct loop *loop)
 451 {
 452   return vec_safe_length (loop->superloops);
 453 }
 454
 455 /* Returns the loop depth of the loop BB belongs to.  */
 456
 457 static inline int
 458 bb_loop_depth (const_basic_block bb)
 459 {
 460   return bb->loop_father ? loop_depth (bb->loop_father) : 0;
 461 }
 462
 463 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 464    loop.  */
 465
 466 static inline struct loop *
 467 loop_outer (const struct loop *loop)
 468 {
 469   unsigned n = vec_safe_length (loop->superloops);
 470
 471   if (n == 0)
 472     return NULL;
 473
 474   return (*loop->superloops)[n - 1];
 475 }
 476
 477 /* Returns true if LOOP has at least one exit edge.  */
 478
 479 static inline bool
 480 loop_has_exit_edges (const struct loop *loop)
 481 {
 482   return loop->exits->next->e != NULL;
 483 }
 484
 485 /* Returns the list of loops in current_loops.  */
 486
 487 static inline vec<loop_p, va_gc> *
 488 get_loops (void)
 489 {
 490   if (!current_loops)
 491     return NULL;
 492
 493   return current_loops->larray;
 494 }
 495
 496 /* Returns the number of loops in current_loops (including the removed
 497    ones and the fake loop that forms the root of the loop tree).  */
 498
 499 static inline unsigned
 500 number_of_loops (void)
 501 {
 502   if (!current_loops)
 503     return 0;
 504
 505   return vec_safe_length (current_loops->larray);
 506 }
 507
 508 /* Returns true if state of the loops satisfies all properties
 509    described by FLAGS.  */
 510
 511 static inline bool
 512 loops_state_satisfies_p (unsigned flags)
 513 {
 514   return (current_loops->state & flags) == flags;
 515 }
 516
 517 /* Sets FLAGS to the loops state.  */
 518
 519 static inline void
 520 loops_state_set (unsigned flags)
 521 {
 522   current_loops->state |= flags;
 523 }
 524
 525 /* Clears FLAGS from the loops state.  */
 526
 527 static inline void
 528 loops_state_clear (unsigned flags)
 529 {
 530   if (!current_loops)
 531     return;
 532   current_loops->state &= ~flags;
 533 }
 534
 535 /* Loop iterators.  */
 536
 537 /* Flags for loop iteration.  */
 538
 539 enum li_flags
 540 {
 541   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 542   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 543                                    starting from innermost ones.  */
 544   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 545 };
 546
 547 /* The iterator for loops.  */
 548
 549 typedef struct
 550 {
 551   /* The list of loops to visit.  */
 552   vec<int> to_visit;
 553
 554   /* The index of the actual loop.  */
 555   unsigned idx;
 556 } loop_iterator;
 557
 558 static inline void
 559 fel_next (loop_iterator *li, loop_p *loop)
 560 {
 561   int anum;
 562
 563   while (li->to_visit.iterate (li->idx, &anum))
 564     {
 565       li->idx++;
 566       *loop = get_loop (anum);
 567       if (*loop)
 568         return;
 569     }
 570
 571   li->to_visit.release ();
 572   *loop = NULL;
 573 }
 574
 575 static inline void
 576 fel_init (loop_iterator *li, loop_p *loop, unsigned flags)
 577 {
 578   struct loop *aloop;
 579   unsigned i;
 580   int mn;
 581
 582   li->idx = 0;
 583   if (!current_loops)
 584     {
 585       li->to_visit.create (0);
 586       *loop = NULL;
 587       return;
 588     }
 589
 590   li->to_visit.create (number_of_loops ());
 591   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 592
 593   if (flags & LI_ONLY_INNERMOST)
 594     {
 595       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 596         if (aloop != NULL
 597             && aloop->inner == NULL
 598             && aloop->num >= mn)
 599           li->to_visit.quick_push (aloop->num);
 600     }
 601   else if (flags & LI_FROM_INNERMOST)
 602     {
 603       /* Push the loops to LI->TO_VISIT in postorder.  */
 604       for (aloop = current_loops->tree_root;
 605            aloop->inner != NULL;
 606            aloop = aloop->inner)
 607         continue;
 608
 609       while (1)
 610         {
 611           if (aloop->num >= mn)
 612             li->to_visit.quick_push (aloop->num);
 613
 614           if (aloop->next)
 615             {
 616               for (aloop = aloop->next;
 617                    aloop->inner != NULL;
 618                    aloop = aloop->inner)
 619                 continue;
 620             }
 621           else if (!loop_outer (aloop))
 622             break;
 623           else
 624             aloop = loop_outer (aloop);
 625         }
 626     }
 627   else
 628     {
 629       /* Push the loops to LI->TO_VISIT in preorder.  */
 630       aloop = current_loops->tree_root;
 631       while (1)
 632         {
 633           if (aloop->num >= mn)
 634             li->to_visit.quick_push (aloop->num);
 635
 636           if (aloop->inner != NULL)
 637             aloop = aloop->inner;
 638           else
 639             {
 640               while (aloop != NULL && aloop->next == NULL)
 641                 aloop = loop_outer (aloop);
 642               if (aloop == NULL)
 643                 break;
 644               aloop = aloop->next;
 645             }
 646         }
 647     }
 648
 649   fel_next (li, loop);
 650 }
 651
 652 #define FOR_EACH_LOOP(LI, LOOP, FLAGS) \
 653   for (fel_init (&(LI), &(LOOP), FLAGS); \
 654        (LOOP); \
 655        fel_next (&(LI), &(LOOP)))
 656
 657 #define FOR_EACH_LOOP_BREAK(LI) \
 658   { \
 659     (LI).to_visit.release (); \
 660     break; \
 661   }
 662
 663 /* The properties of the target.  */
 664 struct target_cfgloop {
 665   /* Number of available registers.  */
 666   unsigned x_target_avail_regs;
 667
 668   /* Number of available registers that are call-clobbered.  */
 669   unsigned x_target_clobbered_regs;
 670
 671   /* Number of registers reserved for temporary expressions.  */
 672   unsigned x_target_res_regs;
 673
 674   /* The cost for register when there still is some reserve, but we are
 675      approaching the number of available registers.  */
 676   unsigned x_target_reg_cost[2];
 677
 678   /* The cost for register when we need to spill.  */
 679   unsigned x_target_spill_cost[2];
 680 };
 681
 682 extern struct target_cfgloop default_target_cfgloop;
 683 #if SWITCHABLE_TARGET
 684 extern struct target_cfgloop *this_target_cfgloop;
 685 #else
 686 #define this_target_cfgloop (&default_target_cfgloop)
 687 #endif
 688
 689 #define target_avail_regs \
 690   (this_target_cfgloop->x_target_avail_regs)
 691 #define target_clobbered_regs \
 692   (this_target_cfgloop->x_target_clobbered_regs)
 693 #define target_res_regs \
 694   (this_target_cfgloop->x_target_res_regs)
 695 #define target_reg_cost \
 696   (this_target_cfgloop->x_target_reg_cost)
 697 #define target_spill_cost \
 698   (this_target_cfgloop->x_target_spill_cost)
 699
 700 /* Register pressure estimation for induction variable optimizations & loop
 701    invariant motion.  */
 702 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 703 extern void init_set_costs (void);
 704
 705 /* Loop optimizer initialization.  */
 706 extern void loop_optimizer_init (unsigned);
 707 extern void loop_optimizer_finalize (void);
 708
 709 /* Optimization passes.  */
 710 extern void unswitch_loops (void);
 711
 712 enum
 713 {
 714   UAP_PEEL = 1,         /* Enables loop peeling.  */
 715   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 716   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 717 };
 718
 719 extern void unroll_and_peel_loops (int);
 720 extern void doloop_optimize_loops (void);
 721 extern void move_loop_invariants (void);
 722 extern bool finite_loop_p (struct loop *);
 723 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 724 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 725
 726 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 727 static inline struct loop *
 728 loop_outermost (struct loop *loop)
 729 {
 730   unsigned n = vec_safe_length (loop->superloops);
 731
 732   if (n <= 1)
 733     return loop;
 734
 735   return (*loop->superloops)[1];
 736 }
 737
 738
 739 #endif /* GCC_CFGLOOP_H */