gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987-2014 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  13 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  14 for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #ifndef GCC_CFGLOOP_H
  21 #define GCC_CFGLOOP_H
  22
  23 #include "double-int.h"
  24 #include "wide-int.h"
  25 #include "bitmap.h"
  26 #include "sbitmap.h"
  27 #include "function.h"
  28
  29 /* Structure to hold decision about unrolling/peeling.  */
  30 enum lpt_dec
  31 {
  32   LPT_NONE,
  33   LPT_PEEL_COMPLETELY,
  34   LPT_PEEL_SIMPLE,
  35   LPT_UNROLL_CONSTANT,
  36   LPT_UNROLL_RUNTIME,
  37   LPT_UNROLL_STUPID
  38 };
  39
  40 struct GTY (()) lpt_decision {
  41   enum lpt_dec decision;
  42   unsigned times;
  43 };
  44
  45 /* The type of extend applied to an IV.  */
  46 enum iv_extend_code
  47 {
  48   IV_SIGN_EXTEND,
  49   IV_ZERO_EXTEND,
  50   IV_UNKNOWN_EXTEND
  51 };
  52
  53 /* The structure describing a bound on number of iterations of a loop.  */
  54
  55 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  56   /* The statement STMT is executed at most ...  */
  57   gimple stmt;
  58
  59   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  60      The + 1 is added for the following reasons:
  61
  62      a) 0 would otherwise be unused, while we would need to care more about
  63         overflows (as MAX + 1 is sometimes produced as the estimate on number
  64         of executions of STMT).
  65      b) it is consistent with the result of number_of_iterations_exit.  */
  66   widest_int bound;
  67
  68   /* True if the statement will cause the loop to be leaved the (at most)
  69      BOUND + 1-st time it is executed, that is, all the statements after it
  70      are executed at most BOUND times.  */
  71   bool is_exit;
  72
  73   /* The next bound in the list.  */
  74   struct nb_iter_bound *next;
  75 };
  76
  77 /* Description of the loop exit.  */
  78
  79 struct GTY (()) loop_exit {
  80   /* The exit edge.  */
  81   edge e;
  82
  83   /* Previous and next exit in the list of the exits of the loop.  */
  84   struct loop_exit *prev;
  85   struct loop_exit *next;
  86
  87   /* Next element in the list of loops from that E exits.  */
  88   struct loop_exit *next_e;
  89 };
  90
  91 typedef struct loop *loop_p;
  92
  93 /* An integer estimation of the number of iterations.  Estimate_state
  94    describes what is the state of the estimation.  */
  95 enum loop_estimation
  96 {
  97   /* Estimate was not computed yet.  */
  98   EST_NOT_COMPUTED,
  99   /* Estimate is ready.  */
 100   EST_AVAILABLE,
 101   EST_LAST
 102 };
 103
 104 /* Structure to hold information for each natural loop.  */
 105 struct GTY ((chain_next ("%h.next"))) loop {
 106   /* Index into loops array.  */
 107   int num;
 108
 109   /* Number of loop insns.  */
 110   unsigned ninsns;
 111
 112   /* Basic block of loop header.  */
 113   basic_block header;
 114
 115   /* Basic block of loop latch.  */
 116   basic_block latch;
 117
 118   /* For loop unrolling/peeling decision.  */
 119   struct lpt_decision lpt_decision;
 120
 121   /* Average number of executed insns per iteration.  */
 122   unsigned av_ninsns;
 123
 124   /* Number of blocks contained within the loop.  */
 125   unsigned num_nodes;
 126
 127   /* Superloops of the loop, starting with the outermost loop.  */
 128   vec<loop_p, va_gc> *superloops;
 129
 130   /* The first inner (child) loop or NULL if innermost loop.  */
 131   struct loop *inner;
 132
 133   /* Link to the next (sibling) loop.  */
 134   struct loop *next;
 135
 136   /* Auxiliary info specific to a pass.  */
 137   PTR GTY ((skip (""))) aux;
 138
 139   /* The number of times the latch of the loop is executed.  This can be an
 140      INTEGER_CST, or a symbolic expression representing the number of
 141      iterations like "N - 1", or a COND_EXPR containing the runtime
 142      conditions under which the number of iterations is non zero.
 143
 144      Don't access this field directly: number_of_latch_executions
 145      computes and caches the computed information in this field.  */
 146   tree nb_iterations;
 147
 148   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 149      valid if any_upper_bound is true.  */
 150   widest_int nb_iterations_upper_bound;
 151
 152   /* An integer giving an estimate on nb_iterations.  Unlike
 153      nb_iterations_upper_bound, there is no guarantee that it is at least
 154      nb_iterations.  */
 155   widest_int nb_iterations_estimate;
 156
 157   bool any_upper_bound;
 158   bool any_estimate;
 159
 160   /* True if the loop can be parallel.  */
 161   bool can_be_parallel;
 162
 163   /* True if -Waggressive-loop-optimizations warned about this loop
 164      already.  */
 165   bool warned_aggressive_loop_optimizations;
 166
 167   /* An integer estimation of the number of iterations.  Estimate_state
 168      describes what is the state of the estimation.  */
 169   enum loop_estimation estimate_state;
 170
 171   /* If > 0, an integer, where the user asserted that for any
 172      I in [ 0, nb_iterations ) and for any J in
 173      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 174      of the loop can be safely evaluated concurrently.  */
 175   int safelen;
 176
 177   /* True if this loop should never be vectorized.  */
 178   bool dont_vectorize;
 179
 180   /* True if we should try harder to vectorize this loop.  */
 181   bool force_vectorize;
 182
 183   /* For SIMD loops, this is a unique identifier of the loop, referenced
 184      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 185      builtins.  */
 186   tree simduid;
 187
 188   /* Upper bound on number of iterations of a loop.  */
 189   struct nb_iter_bound *bounds;
 190
 191   /* Head of the cyclic list of the exits of the loop.  */
 192   struct loop_exit *exits;
 193
 194   /* Number of iteration analysis data for RTL.  */
 195   struct niter_desc *simple_loop_desc;
 196
 197   /* For sanity checking during loop fixup we record here the former
 198      loop header for loops marked for removal.  Note that this prevents
 199      the basic-block from being collected but its index can still be
 200      reused.  */
 201   basic_block former_header;
 202 };
 203
 204 /* Flags for state of loop structure.  */
 205 enum
 206 {
 207   LOOPS_HAVE_PREHEADERS = 1,
 208   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 209   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 210   LOOPS_HAVE_RECORDED_EXITS = 8,
 211   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 212   LOOP_CLOSED_SSA = 32,
 213   LOOPS_NEED_FIXUP = 64,
 214   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 215 };
 216
 217 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 218                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 219 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 220
 221 /* Structure to hold CFG information about natural loops within a function.  */
 222 struct GTY (()) loops {
 223   /* State of loops.  */
 224   int state;
 225
 226   /* Array of the loops.  */
 227   vec<loop_p, va_gc> *larray;
 228
 229   /* Maps edges to the list of their descriptions as loop exits.  Edges
 230      whose sources or destinations have loop_father == NULL (which may
 231      happen during the cfg manipulations) should not appear in EXITS.  */
 232   htab_t GTY((param_is (struct loop_exit))) exits;
 233
 234   /* Pointer to root of loop hierarchy tree.  */
 235   struct loop *tree_root;
 236 };
 237
 238 /* Loop recognition.  */
 239 bool bb_loop_header_p (basic_block);
 240 void init_loops_structure (struct function *, struct loops *, unsigned);
 241 extern struct loops *flow_loops_find (struct loops *);
 242 extern void disambiguate_loops_with_multiple_latches (void);
 243 extern void flow_loops_free (struct loops *);
 244 extern void flow_loops_dump (FILE *,
 245                              void (*)(const struct loop *, FILE *, int), int);
 246 extern void flow_loop_dump (const struct loop *, FILE *,
 247                             void (*)(const struct loop *, FILE *, int), int);
 248 struct loop *alloc_loop (void);
 249 extern void flow_loop_free (struct loop *);
 250 int flow_loop_nodes_find (basic_block, struct loop *);
 251 unsigned fix_loop_structure (bitmap changed_bbs);
 252 bool mark_irreducible_loops (void);
 253 void release_recorded_exits (void);
 254 void record_loop_exits (void);
 255 void rescan_loop_exit (edge, bool, bool);
 256
 257 /* Loop data structure manipulation/querying.  */
 258 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 259 extern void flow_loop_tree_node_remove (struct loop *);
 260 extern void place_new_loop (struct function *, struct loop *);
 261 extern void add_loop (struct loop *, struct loop *);
 262 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 263 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 264 extern struct loop * find_common_loop (struct loop *, struct loop *);
 265 struct loop *superloop_at_depth (struct loop *, unsigned);
 266 struct eni_weights_d;
 267 extern int num_loop_insns (const struct loop *);
 268 extern int average_num_loop_insns (const struct loop *);
 269 extern unsigned get_loop_level (const struct loop *);
 270 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 271 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 272 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 273 extern void mark_loop_exit_edges (void);
 274 extern location_t get_loop_location (struct loop *loop);
 275
 276 /* Loops & cfg manipulation.  */
 277 extern basic_block *get_loop_body (const struct loop *);
 278 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 279                                          unsigned);
 280 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 281 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 282 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 283                                int (*) (const void *, const void *));
 284
 285 extern vec<edge> get_loop_exit_edges (const struct loop *);
 286 extern edge single_exit (const struct loop *);
 287 extern edge single_likely_exit (struct loop *loop);
 288 extern unsigned num_loop_branches (const struct loop *);
 289
 290 extern edge loop_preheader_edge (const struct loop *);
 291 extern edge loop_latch_edge (const struct loop *);
 292
 293 extern void add_bb_to_loop (basic_block, struct loop *);
 294 extern void remove_bb_from_loops (basic_block);
 295
 296 extern void cancel_loop_tree (struct loop *);
 297 extern void delete_loop (struct loop *);
 298
 299 enum
 300 {
 301   CP_SIMPLE_PREHEADERS = 1,
 302   CP_FALLTHRU_PREHEADERS = 2
 303 };
 304
 305 basic_block create_preheader (struct loop *, int);
 306 extern void create_preheaders (int);
 307 extern void force_single_succ_latches (void);
 308
 309 extern void verify_loop_structure (void);
 310
 311 /* Loop analysis.  */
 312 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 313 gcov_type expected_loop_iterations_unbounded (const struct loop *);
 314 extern unsigned expected_loop_iterations (const struct loop *);
 315 extern rtx doloop_condition_get (rtx);
 316
 317
 318 /* Loop manipulation.  */
 319 extern bool can_duplicate_loop_p (const struct loop *loop);
 320
 321 #define DLTHE_FLAG_UPDATE_FREQ  1       /* Update frequencies in
 322                                            duplicate_loop_to_header_edge.  */
 323 #define DLTHE_RECORD_COPY_NUMBER 2      /* Record copy number in the aux
 324                                            field of newly create BB.  */
 325 #define DLTHE_FLAG_COMPLETTE_PEEL 4     /* Update frequencies expecting
 326                                            a complete peeling.  */
 327
 328 extern edge create_empty_if_region_on_edge (edge, tree);
 329 extern struct loop *create_empty_loop_on_edge (edge, tree, tree, tree, tree,
 330                                                tree *, tree *, struct loop *);
 331 extern struct loop * duplicate_loop (struct loop *, struct loop *);
 332 extern void copy_loop_info (struct loop *loop, struct loop *target);
 333 extern void duplicate_subloops (struct loop *, struct loop *);
 334 extern bool duplicate_loop_to_header_edge (struct loop *, edge,
 335                                            unsigned, sbitmap, edge,
 336                                            vec<edge> *, int);
 337 extern struct loop *loopify (edge, edge,
 338                              basic_block, edge, edge, bool,
 339                              unsigned, unsigned);
 340 struct loop * loop_version (struct loop *, void *,
 341                             basic_block *, unsigned, unsigned, unsigned, bool);
 342 extern bool remove_path (edge);
 343 extern void unloop (struct loop *, bool *, bitmap);
 344 extern void scale_loop_frequencies (struct loop *, int, int);
 345 void mark_loop_for_removal (loop_p);
 346
 347
 348 /* Induction variable analysis.  */
 349
 350 /* The description of induction variable.  The things are a bit complicated
 351    due to need to handle subregs and extends.  The value of the object described
 352    by it can be obtained as follows (all computations are done in extend_mode):
 353
 354    Value in i-th iteration is
 355      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 356
 357    If first_special is true, the value in the first iteration is
 358      delta + mult * base
 359
 360    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 361      subreg_{mode} (base + i * step)
 362
 363    The get_iv_value function can be used to obtain these expressions.
 364
 365    ??? Add a third mode field that would specify the mode in that inner
 366    computation is done, which would enable it to be different from the
 367    outer one?  */
 368
 369 struct rtx_iv
 370 {
 371   /* Its base and step (mode of base and step is supposed to be extend_mode,
 372      see the description above).  */
 373   rtx base, step;
 374
 375   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 376      or IV_UNKNOWN_EXTEND).  */
 377   enum iv_extend_code extend;
 378
 379   /* Operations applied in the extended mode.  */
 380   rtx delta, mult;
 381
 382   /* The mode it is extended to.  */
 383   enum machine_mode extend_mode;
 384
 385   /* The mode the variable iterates in.  */
 386   enum machine_mode mode;
 387
 388   /* Whether the first iteration needs to be handled specially.  */
 389   unsigned first_special : 1;
 390 };
 391
 392 /* The description of an exit from the loop and of the number of iterations
 393    till we take the exit.  */
 394
 395 struct GTY(()) niter_desc
 396 {
 397   /* The edge out of the loop.  */
 398   edge out_edge;
 399
 400   /* The other edge leading from the condition.  */
 401   edge in_edge;
 402
 403   /* True if we are able to say anything about number of iterations of the
 404      loop.  */
 405   bool simple_p;
 406
 407   /* True if the loop iterates the constant number of times.  */
 408   bool const_iter;
 409
 410   /* Number of iterations if constant.  */
 411   uint64_t niter;
 412
 413   /* Assumptions under that the rest of the information is valid.  */
 414   rtx assumptions;
 415
 416   /* Assumptions under that the loop ends before reaching the latch,
 417      even if value of niter_expr says otherwise.  */
 418   rtx noloop_assumptions;
 419
 420   /* Condition under that the loop is infinite.  */
 421   rtx infinite;
 422
 423   /* Whether the comparison is signed.  */
 424   bool signed_p;
 425
 426   /* The mode in that niter_expr should be computed.  */
 427   enum machine_mode mode;
 428
 429   /* The number of iterations of the loop.  */
 430   rtx niter_expr;
 431 };
 432
 433 extern void iv_analysis_loop_init (struct loop *);
 434 extern bool iv_analyze (rtx_insn *, rtx, struct rtx_iv *);
 435 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 436 extern bool iv_analyze_expr (rtx_insn *, rtx, enum machine_mode,
 437                              struct rtx_iv *);
 438 extern rtx get_iv_value (struct rtx_iv *, rtx);
 439 extern bool biv_p (rtx_insn *, rtx);
 440 extern void find_simple_exit (struct loop *, struct niter_desc *);
 441 extern void iv_analysis_done (void);
 442
 443 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 444 extern void free_simple_loop_desc (struct loop *loop);
 445
 446 static inline struct niter_desc *
 447 simple_loop_desc (struct loop *loop)
 448 {
 449   return loop->simple_loop_desc;
 450 }
 451
 452 /* Accessors for the loop structures.  */
 453
 454 /* Returns the loop with index NUM from FNs loop tree.  */
 455
 456 static inline struct loop *
 457 get_loop (struct function *fn, unsigned num)
 458 {
 459   return (*loops_for_fn (fn)->larray)[num];
 460 }
 461
 462 /* Returns the number of superloops of LOOP.  */
 463
 464 static inline unsigned
 465 loop_depth (const struct loop *loop)
 466 {
 467   return vec_safe_length (loop->superloops);
 468 }
 469
 470 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 471    loop.  */
 472
 473 static inline struct loop *
 474 loop_outer (const struct loop *loop)
 475 {
 476   unsigned n = vec_safe_length (loop->superloops);
 477
 478   if (n == 0)
 479     return NULL;
 480
 481   return (*loop->superloops)[n - 1];
 482 }
 483
 484 /* Returns true if LOOP has at least one exit edge.  */
 485
 486 static inline bool
 487 loop_has_exit_edges (const struct loop *loop)
 488 {
 489   return loop->exits->next->e != NULL;
 490 }
 491
 492 /* Returns the list of loops in FN.  */
 493
 494 inline vec<loop_p, va_gc> *
 495 get_loops (struct function *fn)
 496 {
 497   struct loops *loops = loops_for_fn (fn);
 498   if (!loops)
 499     return NULL;
 500
 501   return loops->larray;
 502 }
 503
 504 /* Returns the number of loops in FN (including the removed
 505    ones and the fake loop that forms the root of the loop tree).  */
 506
 507 static inline unsigned
 508 number_of_loops (struct function *fn)
 509 {
 510   struct loops *loops = loops_for_fn (fn);
 511   if (!loops)
 512     return 0;
 513
 514   return vec_safe_length (loops->larray);
 515 }
 516
 517 /* Returns true if state of the loops satisfies all properties
 518    described by FLAGS.  */
 519
 520 static inline bool
 521 loops_state_satisfies_p (unsigned flags)
 522 {
 523   return (current_loops->state & flags) == flags;
 524 }
 525
 526 /* Sets FLAGS to the loops state.  */
 527
 528 static inline void
 529 loops_state_set (unsigned flags)
 530 {
 531   current_loops->state |= flags;
 532 }
 533
 534 /* Clears FLAGS from the loops state.  */
 535
 536 static inline void
 537 loops_state_clear (unsigned flags)
 538 {
 539   if (!current_loops)
 540     return;
 541   current_loops->state &= ~flags;
 542 }
 543
 544 /* Loop iterators.  */
 545
 546 /* Flags for loop iteration.  */
 547
 548 enum li_flags
 549 {
 550   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 551   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 552                                    starting from innermost ones.  */
 553   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 554 };
 555
 556 /* The iterator for loops.  */
 557
 558 struct loop_iterator
 559 {
 560   loop_iterator (loop_p *loop, unsigned flags);
 561   ~loop_iterator ();
 562
 563   inline loop_p next ();
 564
 565   /* The list of loops to visit.  */
 566   vec<int> to_visit;
 567
 568   /* The index of the actual loop.  */
 569   unsigned idx;
 570 };
 571
 572 inline loop_p
 573 loop_iterator::next ()
 574 {
 575   int anum;
 576
 577   while (this->to_visit.iterate (this->idx, &anum))
 578     {
 579       this->idx++;
 580       loop_p loop = get_loop (cfun, anum);
 581       if (loop)
 582         return loop;
 583     }
 584
 585   return NULL;
 586 }
 587
 588 inline
 589 loop_iterator::loop_iterator (loop_p *loop, unsigned flags)
 590 {
 591   struct loop *aloop;
 592   unsigned i;
 593   int mn;
 594
 595   this->idx = 0;
 596   if (!current_loops)
 597     {
 598       this->to_visit.create (0);
 599       *loop = NULL;
 600       return;
 601     }
 602
 603   this->to_visit.create (number_of_loops (cfun));
 604   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 605
 606   if (flags & LI_ONLY_INNERMOST)
 607     {
 608       for (i = 0; vec_safe_iterate (current_loops->larray, i, &aloop); i++)
 609         if (aloop != NULL
 610             && aloop->inner == NULL
 611             && aloop->num >= mn)
 612           this->to_visit.quick_push (aloop->num);
 613     }
 614   else if (flags & LI_FROM_INNERMOST)
 615     {
 616       /* Push the loops to LI->TO_VISIT in postorder.  */
 617       for (aloop = current_loops->tree_root;
 618            aloop->inner != NULL;
 619            aloop = aloop->inner)
 620         continue;
 621
 622       while (1)
 623         {
 624           if (aloop->num >= mn)
 625             this->to_visit.quick_push (aloop->num);
 626
 627           if (aloop->next)
 628             {
 629               for (aloop = aloop->next;
 630                    aloop->inner != NULL;
 631                    aloop = aloop->inner)
 632                 continue;
 633             }
 634           else if (!loop_outer (aloop))
 635             break;
 636           else
 637             aloop = loop_outer (aloop);
 638         }
 639     }
 640   else
 641     {
 642       /* Push the loops to LI->TO_VISIT in preorder.  */
 643       aloop = current_loops->tree_root;
 644       while (1)
 645         {
 646           if (aloop->num >= mn)
 647             this->to_visit.quick_push (aloop->num);
 648
 649           if (aloop->inner != NULL)
 650             aloop = aloop->inner;
 651           else
 652             {
 653               while (aloop != NULL && aloop->next == NULL)
 654                 aloop = loop_outer (aloop);
 655               if (aloop == NULL)
 656                 break;
 657               aloop = aloop->next;
 658             }
 659         }
 660     }
 661
 662   *loop = this->next ();
 663 }
 664
 665 inline
 666 loop_iterator::~loop_iterator ()
 667 {
 668   this->to_visit.release ();
 669 }
 670
 671 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 672   for (loop_iterator li(&(LOOP), FLAGS); \
 673        (LOOP); \
 674        (LOOP) = li.next ())
 675
 676 /* The properties of the target.  */
 677 struct target_cfgloop {
 678   /* Number of available registers.  */
 679   unsigned x_target_avail_regs;
 680
 681   /* Number of available registers that are call-clobbered.  */
 682   unsigned x_target_clobbered_regs;
 683
 684   /* Number of registers reserved for temporary expressions.  */
 685   unsigned x_target_res_regs;
 686
 687   /* The cost for register when there still is some reserve, but we are
 688      approaching the number of available registers.  */
 689   unsigned x_target_reg_cost[2];
 690
 691   /* The cost for register when we need to spill.  */
 692   unsigned x_target_spill_cost[2];
 693 };
 694
 695 extern struct target_cfgloop default_target_cfgloop;
 696 #if SWITCHABLE_TARGET
 697 extern struct target_cfgloop *this_target_cfgloop;
 698 #else
 699 #define this_target_cfgloop (&default_target_cfgloop)
 700 #endif
 701
 702 #define target_avail_regs \
 703   (this_target_cfgloop->x_target_avail_regs)
 704 #define target_clobbered_regs \
 705   (this_target_cfgloop->x_target_clobbered_regs)
 706 #define target_res_regs \
 707   (this_target_cfgloop->x_target_res_regs)
 708 #define target_reg_cost \
 709   (this_target_cfgloop->x_target_reg_cost)
 710 #define target_spill_cost \
 711   (this_target_cfgloop->x_target_spill_cost)
 712
 713 /* Register pressure estimation for induction variable optimizations & loop
 714    invariant motion.  */
 715 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 716 extern void init_set_costs (void);
 717
 718 /* Loop optimizer initialization.  */
 719 extern void loop_optimizer_init (unsigned);
 720 extern void loop_optimizer_finalize (void);
 721
 722 /* Optimization passes.  */
 723 enum
 724 {
 725   UAP_PEEL = 1,         /* Enables loop peeling.  */
 726   UAP_UNROLL = 2,       /* Enables unrolling of loops if it seems profitable.  */
 727   UAP_UNROLL_ALL = 4    /* Enables unrolling of all loops.  */
 728 };
 729
 730 extern void unroll_and_peel_loops (int);
 731 extern void doloop_optimize_loops (void);
 732 extern void move_loop_invariants (void);
 733 extern void scale_loop_profile (struct loop *loop, int scale, gcov_type iteration_bound);
 734 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 735
 736 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 737 static inline struct loop *
 738 loop_outermost (struct loop *loop)
 739 {
 740   unsigned n = vec_safe_length (loop->superloops);
 741
 742   if (n <= 1)
 743     return loop;
 744
 745   return (*loop->superloops)[1];
 746 }
 747
 748 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 749 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 750 extern HOST_WIDE_INT get_max_loop_iterations_int (struct loop *);
 751 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 752 extern bool get_max_loop_iterations (struct loop *loop, widest_int *nit);
 753 extern int bb_loop_depth (const_basic_block);
 754
 755 /* Converts VAL to widest_int.  */
 756
 757 static inline widest_int
 758 gcov_type_to_wide_int (gcov_type val)
 759 {
 760   HOST_WIDE_INT a[2];
 761
 762   a[0] = (unsigned HOST_WIDE_INT) val;
 763   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 764      the size of type.  */
 765   val >>= HOST_BITS_PER_WIDE_INT - 1;
 766   val >>= 1;
 767   a[1] = (unsigned HOST_WIDE_INT) val;
 768
 769   return widest_int::from_array (a, 2);
 770 }
 771 #endif /* GCC_CFGLOOP_H */