gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987, 1997, 1998, 1999, 2000, 2001, 2002, 2003, 2004,
   3    2005, 2006, 2007, 2008, 2009, 2010  Free Software Foundation, Inc.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #ifndef GCC_CFGLOOP_H
  22 #define GCC_CFGLOOP_H
  23
  24 #include "basic-block.h"
  25 /* For rtx_code.  */
  26 #include "rtl.h"
  27 #include "vecprim.h"
  28 #include "double-int.h"
  29
  30 #include "bitmap.h"
  31 #include "sbitmap.h"
  32
  33 /* Structure to hold decision about unrolling/peeling.  */
  34 enum lpt_dec
  35 {
  36   LPT_NONE,
  37   LPT_PEEL_COMPLETELY,
  38   LPT_PEEL_SIMPLE,
  39   LPT_UNROLL_CONSTANT,
  40   LPT_UNROLL_RUNTIME,
  41   LPT_UNROLL_STUPID
  42 };
  43
  44 struct GTY (()) lpt_decision {
  45   enum lpt_dec decision;
  46   unsigned times;
  47 };
  48
  49 /* The structure describing a bound on number of iterations of a loop.  */
  50
  51 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  52   /* The statement STMT is executed at most ...  */
  53   gimple stmt;
  54
  55   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  56      The + 1 is added for the following reasons:
  57
  58      a) 0 would otherwise be unused, while we would need to care more about
  59         overflows (as MAX + 1 is sometimes produced as the estimate on number
  60         of executions of STMT).
  61      b) it is consistent with the result of number_of_iterations_exit.  */
  62   double_int bound;
  63
  64   /* True if the statement will cause the loop to be leaved the (at most)
  65      BOUND + 1-st time it is executed, that is, all the statements after it
  66      are executed at most BOUND times.  */
  67   bool is_exit;
  68
  69   /* The next bound in the list.  */
  70   struct nb_iter_bound *next;
  71 };
  72
  73 /* Description of the loop exit.  */
  74
  75 struct GTY (()) loop_exit {
  76   /* The exit edge.  */
  77   struct edge_def *e;
  78
  79   /* Previous and next exit in the list of the exits of the loop.  */
  80   struct loop_exit *prev;
  81   struct loop_exit *next;
  82
  83   /* Next element in the list of loops from that E exits.  */
  84   struct loop_exit *next_e;
  85 };
  86
  87 typedef struct loop *loop_p;
  88 DEF_VEC_P (loop_p);
  89 DEF_VEC_ALLOC_P (loop_p, heap);
  90 DEF_VEC_ALLOC_P (loop_p, gc);
  91
  92 /* An integer estimation of the number of iterations.  Estimate_state
  93    describes what is the state of the estimation.  */
  94 enum loop_estimation
  95 {
  96   /* Estimate was not computed yet.  */
  97   EST_NOT_COMPUTED,
  98   /* Estimate is ready.  */
  99   EST_AVAILABLE
 100 };
 101
 102 /* Structure to hold information for each natural loop.  */
 103 struct GTY ((chain_next ("%h.next"))) loop {
 104   /* Index into loops array.  */
 105   int num;
 106
 107   /* Number of loop insns.  */
 108   unsigned ninsns;
 109
 110   /* Basic block of loop header.  */
 111   struct basic_block_def *header;
 112
 113   /* Basic block of loop latch.  */
 114   struct basic_block_def *latch;
 115
 116   /* For loop unrolling/peeling decision.  */
 117   struct lpt_decision lpt_decision;
 118
 119   /* Average number of executed insns per iteration.  */
 120   unsigned av_ninsns;
 121
 122   /* Number of blocks contained within the loop.  */
 123   unsigned num_nodes;
 124
 125   /* Superloops of the loop, starting with the outermost loop.  */
 126   VEC (loop_p, gc) *superloops;
 127
 128   /* The first inner (child) loop or NULL if innermost loop.  */
 129   struct loop *inner;
 130
 131   /* Link to the next (sibling) loop.  */
 132   struct loop *next;
 133
 134   /* Auxiliary info specific to a pass.  */
 135   PTR GTY ((skip (""))) aux;
 136
 137   /* The number of times the latch of the loop is executed.  This can be an
 138      INTEGER_CST, or a symbolic expression representing the number of
 139      iterations like "N - 1", or a COND_EXPR containing the runtime
 140      conditions under which the number of iterations is non zero.
 141
 142      Don't access this field directly: number_of_latch_executions
 143      computes and caches the computed information in this field.  */
 144   tree nb_iterations;
 145
 146   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 147      valid if any_upper_bound is true.  */
 148   double_int nb_iterations_upper_bound;
 149
 150   /* An integer giving an estimate on nb_iterations.  Unlike
 151      nb_iterations_upper_bound, there is no guarantee that it is at least
 152      nb_iterations.  */
 153   double_int nb_iterations_estimate;
 154
 155   bool any_upper_bound;
 156   bool any_estimate;
 157
 158   /* True if the loop can be parallel.  */
 159   bool can_be_parallel;
 160
 161   /* An integer estimation of the number of iterations.  Estimate_state
 162      describes what is the state of the estimation.  */
 163   enum loop_estimation estimate_state;
 164
 165   /* Upper bound on number of iterations of a loop.  */
 166   struct nb_iter_bound *bounds;
 167
 168   /* Head of the cyclic list of the exits of the loop.  */
 169   struct loop_exit *exits;
 170 };
 171
 172 /* Flags for state of loop structure.  */
 173 enum
 174 {
 175   LOOPS_HAVE_PREHEADERS = 1,
 176   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 177   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 178   LOOPS_HAVE_RECORDED_EXITS = 8,
 179   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 180   LOOP_CLOSED_SSA = 32,
 181   LOOPS_NEED_FIXUP = 64,
 182   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 183 };
 184
 185 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 186                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 187 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 188
 189 /* Structure to hold CFG information about natural loops within a function.  */
 190 struct GTY (()) loops {
 191   /* State of loops.  */
 192   int state;
 193
 194   /* Array of the loops.  */
 195   VEC (loop_p, gc) *larray;
 196
 197   /* Maps edges to the list of their descriptions as loop exits.  Edges
 198      whose sources or destinations have loop_father == NULL (which may
 199      happen during the cfg manipulations) should not appear in EXITS.  */
 200   htab_t GTY((param_is (struct loop_exit))) exits;
 201
 202   /* Pointer to root of loop hierarchy tree.  */
 203   struct loop *tree_root;
 204 };
 205
 206 /* Loop recognition.  */
 207 extern int flow_loops_find (struct loops *);
 208 extern void disambiguate_loops_with_multiple_latches (void);
 209 extern void flow_loops_free (struct loops *);
 210 extern void flow_loops_dump (FILE *,
 211                              void (*)(const struct loop *, FILE *, int), int);
 212 extern void flow_loop_dump (const struct loop *, FILE *,
 213                             void (*)(const struct loop *, FILE *, int), int);
 214 struct loop *alloc_loop (void);
 215 extern void flow_loop_free (struct loop *);
 216 int flow_loop_nodes_find (basic_block, struct loop *);
 217 void fix_loop_structure (bitmap changed_bbs);
 218 bool mark_irreducible_loops (void);
 219 void release_recorded_exits (void);
 220 void record_loop_exits (void);
 221 void rescan_loop_exit (edge, bool, bool);
 222
 223 /* Loop data structure manipulation/querying.  */
 224 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 225 extern void flow_loop_tree_node_remove (struct loop *);
 226 extern void add_loop (struct loop *, struct loop *);
 227 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 228 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 229 extern struct loop * find_common_loop (struct loop *, struct loop *);
 230 struct loop *superloop_at_depth (struct loop *, unsigned);
 231 struct eni_weights_d;
 232 extern unsigned tree_num_loop_insns (struct loop *, struct eni_weights_d *);
 233 extern int num_loop_insns (const struct loop *);
 234 extern int average_num_loop_insns (const struct loop *);
 235 extern unsigned get_loop_level (const struct loop *);
 236 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 237 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 238 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 239 extern void mark_loop_exit_edges (void);
 240
 241 /* Loops & cfg manipulation.  */
 242 extern basic_block *get_loop_body (const struct loop *);
 243 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 244                                          unsigned);
 245 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 246 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 247 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 248                                int (*) (const void *, const void *));
 249
 250 extern VEC (edge, heap) *get_loop_exit_edges (const struct loop *);
 251 edge single_exit (const struct loop *);
 252 extern unsigned num_loop_branches (const struct loop *);
 253
 254 extern edge loop_preheader_edge (const struct loop *);
 255 extern edge loop_latch_edge (const struct loop *);
 256
 257 extern void add_bb_to_loop (basic_block, struct loop *);
 258 extern void remove_bb_from_loops (basic_block);
 259
 260 extern void cancel_loop_tree (struct loop *);
 261 extern void delete_loop (struct loop *);
 262
 263 enum
 264 {
 265   CP_SIMPLE_PREHEADERS = 1,
 266   CP_FALLTHRU_PREHEADERS = 2
 267 };
 268
 269 basic_block create_preheader (struct loop *, int);
 270 extern void create_preheaders (int);
 271 extern void force_single_succ_latches (void);
 272
 273 extern void verify_loop_structure (void);
 274
 275 /* Loop analysis.  */
 276 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 277 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 278 extern unsigned expected_loop_iterations (const struct loop *);
 279 extern rtx doloop_condition_get (rtx);
 280
 281 void estimate_numbers_of_iterations_loop (struct loop *, bool);
 282 HOST_WIDE_INT estimated_loop_iterations_int (struct loop *, bool);
 283 HOST_WIDE_INT max_stmt_executions_int (struct loop *, bool);
 284 bool estimated_loop_iterations (struct loop *, bool, double_int *);
 285 bool max_stmt_executions (struct loop *, bool, double_int *);
 286
 287 /* Loop manipulation.  */
 288 extern bool can_duplicate_loop_p (const struct loop *loop);
 289
 290 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 291                                            duplicate_loop_to_header_edge.  */
 292 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 293                                            field of newly create BB.  */
 294 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 295                                            a complete peeling.  */
 296
 297 extern edge create_empty_if_region_on_edge (edge, tree);
 298 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 299                                                tree *, tree *, struct loop *);
 300 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 301 extern void duplicate_subloops (struct loop *, struct loop *);
 302 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 303                                            unsigned, sbitmap, edge,
 304                                            VEC (edge, heap) **, int);
 305 extern struct loop *loopify (edge, edge,
 306                              basic_block, edge, edge, bool,
 307                              unsigned, unsigned);
 308 struct loop * loop_version (struct loop *, void *,
 309                             basic_block *, unsigned, unsigned, unsigned, bool);
 310 extern bool remove_path (edge);
 311 void scale_loop_frequencies (struct loop *, int, int);
 312
 313 /* Induction variable analysis.  */
 314
 315 /* The description of induction variable.  The things are a bit complicated
 316    due to need to handle subregs and extends.  The value of the object described
 317    by it can be obtained as follows (all computations are done in extend_mode):
 318
 319    Value in i-th iteration is
 320      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 321
 322    If first_special is true, the value in the first iteration is
 323      delta + mult * base
 324
 325    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 326      subreg_{mode} (base + i * step)
 327
 328    The get_iv_value function can be used to obtain these expressions.
 329
 330    ??? Add a third mode field that would specify the mode in that inner
 331    computation is done, which would enable it to be different from the
 332    outer one?  */
 333
 334 struct rtx_iv
 335 {
 336   /* Its base and step (mode of base and step is supposed to be extend_mode,
 337      see the description above).  */
 338   rtx base, step;
 339
 340   /* The type of extend applied to it (SIGN_EXTEND, ZERO_EXTEND or UNKNOWN).  */
 341   enum rtx_code extend;
 342
 343   /* Operations applied in the extended mode.  */
 344   rtx delta, mult;
 345
 346   /* The mode it is extended to.  */
 347   enum machine_mode extend_mode;
 348
 349   /* The mode the variable iterates in.  */
 350   enum machine_mode mode;
 351
 352   /* Whether the first iteration needs to be handled specially.  */
 353   unsigned first_special : 1;
 354 };
 355
 356 /* The description of an exit from the loop and of the number of iterations
 357    till we take the exit.  */
 358
 359 struct niter_desc
 360 {
 361   /* The edge out of the loop.  */
 362   edge out_edge;
 363
 364   /* The other edge leading from the condition.  */
 365   edge in_edge;
 366
 367   /* True if we are able to say anything about number of iterations of the
 368      loop.  */
 369   bool simple_p;
 370
 371   /* True if the loop iterates the constant number of times.  */
 372   bool const_iter;
 373
 374   /* Number of iterations if constant.  */
 375   unsigned HOST_WIDEST_INT niter;
 376
 377   /* Upper bound on the number of iterations.  */
 378   unsigned HOST_WIDEST_INT niter_max;
 379
 380   /* Assumptions under that the rest of the information is valid.  */
 381   rtx assumptions;
 382
 383   /* Assumptions under that the loop ends before reaching the latch,
 384      even if value of niter_expr says otherwise.  */
 385   rtx noloop_assumptions;
 386
 387   /* Condition under that the loop is infinite.  */
 388   rtx infinite;
 389
 390   /* Whether the comparison is signed.  */
 391   bool signed_p;
 392
 393   /* The mode in that niter_expr should be computed.  */
 394   enum machine_mode mode;
 395
 396   /* The number of iterations of the loop.  */
 397   rtx niter_expr;
 398 };
 399
 400 extern void iv_analysis_loop_init (struct loop *);
 401 extern bool iv_analyze (rtx, rtx, struct rtx_iv *);
 402 extern bool iv_analyze_result (rtx, rtx, struct rtx_iv *);
 403 extern bool iv_analyze_expr (rtx, rtx, enum machine_mode, struct rtx_iv *);
 404 extern rtx get_iv_value (struct rtx_iv *, rtx);
 405 extern bool biv_p (rtx, rtx);
 406 extern void find_simple_exit (struct loop *, struct niter_desc *);
 407 extern void iv_analysis_done (void);
 408
 409 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 410 extern void free_simple_loop_desc (struct loop *loop);
 411
 412 static inline struct niter_desc *
 413 simple_loop_desc (struct loop *loop)
 414 {
 415   return (struct niter_desc *) loop->aux;
 416 }
 417
 418 /* Accessors for the loop structures.  */
 419
 420 /* Returns the loop with index NUM from current_loops.  */
 421
 422 static inline struct loop *
 423 get_loop (unsigned num)
 424 {
 425   return VEC_index (loop_p, current_loops->larray, num);
 426 }
 427
 428 /* Returns the number of superloops of LOOP.  */
 429
 430 static inline unsigned
 431 loop_depth (const struct loop *loop)
 432 {
 433   return VEC_length (loop_p, loop->superloops);
 434 }
 435
 436 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 437    loop.  */
 438
 439 static inline struct loop *
 440 loop_outer (const struct loop *loop)
 441 {
 442   unsigned n = VEC_length (loop_p, loop->superloops);
 443
 444   if (n == 0)
 445     return NULL;
 446
 447   return VEC_index (loop_p, loop->superloops, n - 1);
 448 }
 449
 450 /* Returns true if LOOP has at least one exit edge.  */
 451
 452 static inline bool
 453 loop_has_exit_edges (const struct loop *loop)
 454 {
 455   return loop->exits->next->e != NULL;
 456 }
 457
 458 /* Returns the list of loops in current_loops.  */
 459
 460 static inline VEC (loop_p, gc) *
 461 get_loops (void)
 462 {
 463   if (!current_loops)
 464     return NULL;
 465
 466   return current_loops->larray;
 467 }
 468
 469 /* Returns the number of loops in current_loops (including the removed
 470    ones and the fake loop that forms the root of the loop tree).  */
 471
 472 static inline unsigned
 473 number_of_loops (void)
 474 {
 475   if (!current_loops)
 476     return 0;
 477
 478   return VEC_length (loop_p, current_loops->larray);
 479 }
 480
 481 /* Returns true if state of the loops satisfies all properties
 482    described by FLAGS.  */
 483
 484 static inline bool
 485 loops_state_satisfies_p (unsigned flags)
 486 {
 487   return (current_loops->state & flags) == flags;
 488 }
 489
 490 /* Sets FLAGS to the loops state.  */
 491
 492 static inline void
 493 loops_state_set (unsigned flags)
 494 {
 495   current_loops->state |= flags;
 496 }
 497
 498 /* Clears FLAGS from the loops state.  */
 499
 500 static inline void
 501 loops_state_clear (unsigned flags)
 502 {
 503   if (!current_loops)
 504     return;
 505   current_loops->state &= ~flags;
 506 }
 507
 508 /* Loop iterators.  */
 509
 510 /* Flags for loop iteration.  */
 511
 512 enum li_flags
 513 {
 514   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 515   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 516                                    starting from innermost ones.  */
 517   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 518 };
 519
 520 /* The iterator for loops.  */
 521
 522 typedef struct
 523 {
 524   /* The list of loops to visit.  */
 525   VEC(int,heap) *to_visit;
 526
 527   /* The index of the actual loop.  */
 528   unsigned idx;
 529 } loop_iterator;
 530
 531 static inline void
 532 fel_next (loop_iterator *li, loop_p *loop)
 533 {
 534   int anum;
 535
 536   while (VEC_iterate (int, li->to_visit, li->idx, anum))
 537     {
 538       li->idx++;
 539       *loop = get_loop (anum);
 540       if (*loop)
 541         return;
 542     }
 543
 544   VEC_free (int, heap, li->to_visit);
 545   *loop = NULL;
 546 }
 547
 548 static inline void
 549 fel_init (loop_iterator *li, loop_p *loop, unsigned flags)
 550 {
 551   struct loop *aloop;
 552   unsigned i;
 553   int mn;
 554
 555   li->idx = 0;
 556   if (!current_loops)
 557     {
 558       li->to_visit = NULL;
 559       *loop = NULL;
 560       return;
 561     }
 562
 563   li->to_visit = VEC_alloc (int, heap, number_of_loops ());
 564   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 565
 566   if (flags & LI_ONLY_INNERMOST)
 567     {
 568       for (i = 0; VEC_iterate (loop_p, current_loops->larray, i, aloop); i++)
 569         if (aloop != NULL
 570             && aloop->inner == NULL
 571             && aloop->num >= mn)
 572           VEC_quick_push (int, li->to_visit, aloop->num);
 573     }
 574   else if (flags & LI_FROM_INNERMOST)
 575     {
 576       /* Push the loops to LI->TO_VISIT in postorder.  */
 577       for (aloop = current_loops->tree_root;
 578            aloop->inner != NULL;
 579            aloop = aloop->inner)
 580         continue;
 581
 582       while (1)
 583         {
 584           if (aloop->num >= mn)
 585             VEC_quick_push (int, li->to_visit, aloop->num);
 586
 587           if (aloop->next)
 588             {
 589               for (aloop = aloop->next;
 590                    aloop->inner != NULL;
 591                    aloop = aloop->inner)
 592                 continue;
 593             }
 594           else if (!loop_outer (aloop))
 595             break;
 596           else
 597             aloop = loop_outer (aloop);
 598         }
 599     }
 600   else
 601     {
 602       /* Push the loops to LI->TO_VISIT in preorder.  */
 603       aloop = current_loops->tree_root;
 604       while (1)
 605         {
 606           if (aloop->num >= mn)
 607             VEC_quick_push (int, li->to_visit, aloop->num);
 608
 609           if (aloop->inner != NULL)
 610             aloop = aloop->inner;
 611           else
 612             {
 613               while (aloop != NULL && aloop->next == NULL)
 614                 aloop = loop_outer (aloop);
 615               if (aloop == NULL)
 616                 break;
 617               aloop = aloop->next;
 618             }
 619         }
 620     }
 621
 622   fel_next (li, loop);
 623 }
 624
 625 #define FOR_EACH_LOOP(LI, LOOP, FLAGS) \
 626   for (fel_init (&(LI), &(LOOP), FLAGS); \
 627        (LOOP); \
 628        fel_next (&(LI), &(LOOP)))
 629
 630 #define FOR_EACH_LOOP_BREAK(LI) \
 631   { \
 632     VEC_free (int, heap, (LI)->to_visit); \
 633     break; \
 634   }
 635
 636 /* The properties of the target.  */
 637 struct target_cfgloop {
 638   /* Number of available registers.  */
 639   unsigned x_target_avail_regs;
 640
 641   /* Number of available registers that are call-clobbered.  */
 642   unsigned x_target_clobbered_regs;
 643
 644   /* Number of registers reserved for temporary expressions.  */
 645   unsigned x_target_res_regs;
 646
 647   /* The cost for register when there still is some reserve, but we are
 648      approaching the number of available registers.  */
 649   unsigned x_target_reg_cost[2];
 650
 651   /* The cost for register when we need to spill.  */
 652   unsigned x_target_spill_cost[2];
 653 };
 654
 655 extern struct target_cfgloop default_target_cfgloop;
 656 #if SWITCHABLE_TARGET
 657 extern struct target_cfgloop *this_target_cfgloop;
 658 #else
 659 #define this_target_cfgloop (&default_target_cfgloop)
 660 #endif
 661
 662 #define target_avail_regs \
 663   (this_target_cfgloop->x_target_avail_regs)
 664 #define target_clobbered_regs \
 665   (this_target_cfgloop->x_target_clobbered_regs)
 666 #define target_res_regs \
 667   (this_target_cfgloop->x_target_res_regs)
 668 #define target_reg_cost \
 669   (this_target_cfgloop->x_target_reg_cost)
 670 #define target_spill_cost \
 671   (this_target_cfgloop->x_target_spill_cost)
 672
 673 /* Register pressure estimation for induction variable optimizations & loop
 674    invariant motion.  */
 675 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 676 extern void init_set_costs (void);
 677
 678 /* Loop optimizer initialization.  */
 679 extern void loop_optimizer_init (unsigned);
 680 extern void loop_optimizer_finalize (void);
 681
 682 /* Optimization passes.  */
 683 extern void unswitch_loops (void);
 684
 685 enum
 686 {
 687   UAP_PEEL = 1,         /* Enables loop peeling.  */
 688   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 689   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 690 };
 691
 692 extern void unroll_and_peel_loops (int);
 693 extern void doloop_optimize_loops (void);
 694 extern void move_loop_invariants (void);
 695 extern bool finite_loop_p (struct loop *);
 696
 697 #endif /* GCC_CFGLOOP_H */