gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987-2017 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 "cfgloopmanip.h"
  24
  25 /* Structure to hold decision about unrolling/peeling.  */
  26 enum lpt_dec
  27 {
  28   LPT_NONE,
  29   LPT_UNROLL_CONSTANT,
  30   LPT_UNROLL_RUNTIME,
  31   LPT_UNROLL_STUPID
  32 };
  33
  34 struct GTY (()) lpt_decision {
  35   enum lpt_dec decision;
  36   unsigned times;
  37 };
  38
  39 /* The type of extend applied to an IV.  */
  40 enum iv_extend_code
  41 {
  42   IV_SIGN_EXTEND,
  43   IV_ZERO_EXTEND,
  44   IV_UNKNOWN_EXTEND
  45 };
  46
  47 /* The structure describing a bound on number of iterations of a loop.  */
  48
  49 struct GTY ((chain_next ("%h.next"))) nb_iter_bound {
  50   /* The statement STMT is executed at most ...  */
  51   gimple *stmt;
  52
  53   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  54      The + 1 is added for the following reasons:
  55
  56      a) 0 would otherwise be unused, while we would need to care more about
  57         overflows (as MAX + 1 is sometimes produced as the estimate on number
  58         of executions of STMT).
  59      b) it is consistent with the result of number_of_iterations_exit.  */
  60   widest_int bound;
  61
  62   /* True if the statement will cause the loop to be leaved the (at most)
  63      BOUND + 1-st time it is executed, that is, all the statements after it
  64      are executed at most BOUND times.  */
  65   bool is_exit;
  66
  67   /* The next bound in the list.  */
  68   struct nb_iter_bound *next;
  69 };
  70
  71 /* Description of the loop exit.  */
  72
  73 struct GTY ((for_user)) loop_exit {
  74   /* The exit edge.  */
  75   edge e;
  76
  77   /* Previous and next exit in the list of the exits of the loop.  */
  78   struct loop_exit *prev;
  79   struct loop_exit *next;
  80
  81   /* Next element in the list of loops from that E exits.  */
  82   struct loop_exit *next_e;
  83 };
  84
  85 struct loop_exit_hasher : ggc_ptr_hash<loop_exit>
  86 {
  87   typedef edge compare_type;
  88
  89   static hashval_t hash (loop_exit *);
  90   static bool equal (loop_exit *, edge);
  91   static void remove (loop_exit *);
  92 };
  93
  94 typedef struct loop *loop_p;
  95
  96 /* An integer estimation of the number of iterations.  Estimate_state
  97    describes what is the state of the estimation.  */
  98 enum loop_estimation
  99 {
 100   /* Estimate was not computed yet.  */
 101   EST_NOT_COMPUTED,
 102   /* Estimate is ready.  */
 103   EST_AVAILABLE,
 104   EST_LAST
 105 };
 106
 107 /* The structure describing non-overflow control induction variable for
 108    loop's exit edge.  */
 109 struct GTY ((chain_next ("%h.next"))) control_iv {
 110   tree base;
 111   tree step;
 112   struct control_iv *next;
 113 };
 114
 115 /* Structure to hold information for each natural loop.  */
 116 struct GTY ((chain_next ("%h.next"))) loop {
 117   /* Index into loops array.  Note indices will never be reused after loop
 118      is destroyed.  */
 119   int num;
 120
 121   /* Number of loop insns.  */
 122   unsigned ninsns;
 123
 124   /* Basic block of loop header.  */
 125   basic_block header;
 126
 127   /* Basic block of loop latch.  */
 128   basic_block latch;
 129
 130   /* For loop unrolling/peeling decision.  */
 131   struct lpt_decision lpt_decision;
 132
 133   /* Average number of executed insns per iteration.  */
 134   unsigned av_ninsns;
 135
 136   /* Number of blocks contained within the loop.  */
 137   unsigned num_nodes;
 138
 139   /* Superloops of the loop, starting with the outermost loop.  */
 140   vec<loop_p, va_gc> *superloops;
 141
 142   /* The first inner (child) loop or NULL if innermost loop.  */
 143   struct loop *inner;
 144
 145   /* Link to the next (sibling) loop.  */
 146   struct loop *next;
 147
 148   /* Auxiliary info specific to a pass.  */
 149   PTR GTY ((skip (""))) aux;
 150
 151   /* The number of times the latch of the loop is executed.  This can be an
 152      INTEGER_CST, or a symbolic expression representing the number of
 153      iterations like "N - 1", or a COND_EXPR containing the runtime
 154      conditions under which the number of iterations is non zero.
 155
 156      Don't access this field directly: number_of_latch_executions
 157      computes and caches the computed information in this field.  */
 158   tree nb_iterations;
 159
 160   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 161      valid if any_upper_bound is true.  */
 162   widest_int nb_iterations_upper_bound;
 163
 164   widest_int nb_iterations_likely_upper_bound;
 165
 166   /* An integer giving an estimate on nb_iterations.  Unlike
 167      nb_iterations_upper_bound, there is no guarantee that it is at least
 168      nb_iterations.  */
 169   widest_int nb_iterations_estimate;
 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   /* Constraints are generally set by consumers and affect certain
 178      semantics of niter analyzer APIs.  Currently the APIs affected are
 179      number_of_iterations_exit* functions and their callers.  One typical
 180      use case of constraints is to vectorize possibly infinite loop:
 181
 182        1) Compute niter->assumptions by calling niter analyzer API and
 183           record it as possible condition for loop versioning.
 184        2) Clear buffered result of niter/scev analyzer.
 185        3) Set constraint LOOP_C_FINITE assuming the loop is finite.
 186        4) Analyze data references.  Since data reference analysis depends
 187           on niter/scev analyzer, the point is that niter/scev analysis
 188           is done under circumstance of LOOP_C_FINITE constraint.
 189        5) Version the loop with niter->assumptions computed in step 1).
 190        6) Vectorize the versioned loop in which niter->assumptions is
 191           checked to be true.
 192        7) Update constraints in versioned loops so that niter analyzer
 193           in following passes can use it.
 194
 195      Note consumers are usually the loop optimizers and it is consumers'
 196      responsibility to set/clear constraints correctly.  Failing to do
 197      that might result in hard to track down bugs in niter/scev consumers.  */
 198   unsigned constraints;
 199
 200   /* An integer estimation of the number of iterations.  Estimate_state
 201      describes what is the state of the estimation.  */
 202   ENUM_BITFIELD(loop_estimation) estimate_state : 8;
 203
 204   unsigned any_upper_bound : 1;
 205   unsigned any_estimate : 1;
 206   unsigned any_likely_upper_bound : 1;
 207
 208   /* True if the loop can be parallel.  */
 209   unsigned can_be_parallel : 1;
 210
 211   /* True if -Waggressive-loop-optimizations warned about this loop
 212      already.  */
 213   unsigned warned_aggressive_loop_optimizations : 1;
 214
 215   /* True if this loop should never be vectorized.  */
 216   unsigned dont_vectorize : 1;
 217
 218   /* True if we should try harder to vectorize this loop.  */
 219   unsigned force_vectorize : 1;
 220
 221   /* True if the loop is part of an oacc kernels region.  */
 222   unsigned in_oacc_kernels_region : 1;
 223
 224   /* The number of times to unroll the loop.  0 means no information given,
 225      just do what we always do.  A value of 1 means do not unroll the loop.
 226      A value of USHRT_MAX means unroll with no specific unrolling factor.
 227      Other values means unroll with the given unrolling factor.  */
 228   unsigned short unroll;
 229
 230   /* For SIMD loops, this is a unique identifier of the loop, referenced
 231      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 232      builtins.  */
 233   tree simduid;
 234
 235   /* In loop optimization, it's common to generate loops from the original
 236      loop.  This field records the index of the original loop which can be
 237      used to track the original loop from newly generated loops.  This can
 238      be done by calling function get_loop (cfun, orig_loop_num).  Note the
 239      original loop could be destroyed for various reasons thus no longer
 240      exists, as a result, function call to get_loop returns NULL pointer.
 241      In this case, this field should not be used and needs to be cleared
 242      whenever possible.  */
 243   int orig_loop_num;
 244
 245   /* Upper bound on number of iterations of a loop.  */
 246   struct nb_iter_bound *bounds;
 247
 248   /* Non-overflow control ivs of a loop.  */
 249   struct control_iv *control_ivs;
 250
 251   /* Head of the cyclic list of the exits of the loop.  */
 252   struct loop_exit *exits;
 253
 254   /* Number of iteration analysis data for RTL.  */
 255   struct niter_desc *simple_loop_desc;
 256
 257   /* For sanity checking during loop fixup we record here the former
 258      loop header for loops marked for removal.  Note that this prevents
 259      the basic-block from being collected but its index can still be
 260      reused.  */
 261   basic_block former_header;
 262 };
 263
 264 /* Set if the loop is known to be infinite.  */
 265 #define LOOP_C_INFINITE         (1 << 0)
 266 /* Set if the loop is known to be finite without any assumptions.  */
 267 #define LOOP_C_FINITE           (1 << 1)
 268
 269 /* Set C to the LOOP constraint.  */
 270 static inline void
 271 loop_constraint_set (struct loop *loop, unsigned c)
 272 {
 273   loop->constraints |= c;
 274 }
 275
 276 /* Clear C from the LOOP constraint.  */
 277 static inline void
 278 loop_constraint_clear (struct loop *loop, unsigned c)
 279 {
 280   loop->constraints &= ~c;
 281 }
 282
 283 /* Check if C is set in the LOOP constraint.  */
 284 static inline bool
 285 loop_constraint_set_p (struct loop *loop, unsigned c)
 286 {
 287   return (loop->constraints & c) == c;
 288 }
 289
 290 /* Flags for state of loop structure.  */
 291 enum
 292 {
 293   LOOPS_HAVE_PREHEADERS = 1,
 294   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 295   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 296   LOOPS_HAVE_RECORDED_EXITS = 8,
 297   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 298   LOOP_CLOSED_SSA = 32,
 299   LOOPS_NEED_FIXUP = 64,
 300   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 301 };
 302
 303 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 304                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 305 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 306
 307 /* Structure to hold CFG information about natural loops within a function.  */
 308 struct GTY (()) loops {
 309   /* State of loops.  */
 310   int state;
 311
 312   /* Array of the loops.  */
 313   vec<loop_p, va_gc> *larray;
 314
 315   /* Maps edges to the list of their descriptions as loop exits.  Edges
 316      whose sources or destinations have loop_father == NULL (which may
 317      happen during the cfg manipulations) should not appear in EXITS.  */
 318   hash_table<loop_exit_hasher> *GTY(()) exits;
 319
 320   /* Pointer to root of loop hierarchy tree.  */
 321   struct loop *tree_root;
 322 };
 323
 324 /* Loop recognition.  */
 325 bool bb_loop_header_p (basic_block);
 326 void init_loops_structure (struct function *, struct loops *, unsigned);
 327 extern struct loops *flow_loops_find (struct loops *);
 328 extern void disambiguate_loops_with_multiple_latches (void);
 329 extern void flow_loops_free (struct loops *);
 330 extern void flow_loops_dump (FILE *,
 331                              void (*)(const struct loop *, FILE *, int), int);
 332 extern void flow_loop_dump (const struct loop *, FILE *,
 333                             void (*)(const struct loop *, FILE *, int), int);
 334 struct loop *alloc_loop (void);
 335 extern void flow_loop_free (struct loop *);
 336 int flow_loop_nodes_find (basic_block, struct loop *);
 337 unsigned fix_loop_structure (bitmap changed_bbs);
 338 bool mark_irreducible_loops (void);
 339 void release_recorded_exits (function *);
 340 void record_loop_exits (void);
 341 void rescan_loop_exit (edge, bool, bool);
 342 void sort_sibling_loops (function *);
 343
 344 /* Loop data structure manipulation/querying.  */
 345 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 346 extern void flow_loop_tree_node_remove (struct loop *);
 347 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 348 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 349 extern struct loop * find_common_loop (struct loop *, struct loop *);
 350 struct loop *superloop_at_depth (struct loop *, unsigned);
 351 struct eni_weights;
 352 extern int num_loop_insns (const struct loop *);
 353 extern int average_num_loop_insns (const struct loop *);
 354 extern unsigned get_loop_level (const struct loop *);
 355 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 356 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 357 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 358 extern void mark_loop_exit_edges (void);
 359 extern location_t get_loop_location (struct loop *loop);
 360
 361 /* Loops & cfg manipulation.  */
 362 extern basic_block *get_loop_body (const struct loop *);
 363 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 364                                          unsigned);
 365 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 366 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 367 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 368                                int (*) (const void *, const void *));
 369
 370 extern vec<edge> get_loop_exit_edges (const struct loop *);
 371 extern edge single_exit (const struct loop *);
 372 extern edge single_likely_exit (struct loop *loop);
 373 extern unsigned num_loop_branches (const struct loop *);
 374
 375 extern edge loop_preheader_edge (const struct loop *);
 376 extern edge loop_latch_edge (const struct loop *);
 377
 378 extern void add_bb_to_loop (basic_block, struct loop *);
 379 extern void remove_bb_from_loops (basic_block);
 380
 381 extern void cancel_loop_tree (struct loop *);
 382 extern void delete_loop (struct loop *);
 383
 384
 385 extern void verify_loop_structure (void);
 386
 387 /* Loop analysis.  */
 388 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 389 gcov_type expected_loop_iterations_unbounded (const struct loop *,
 390                                               bool *read_profile_p = NULL);
 391 extern unsigned expected_loop_iterations (struct loop *);
 392 extern rtx doloop_condition_get (rtx_insn *);
 393
 394 void mark_loop_for_removal (loop_p);
 395
 396 /* Induction variable analysis.  */
 397
 398 /* The description of induction variable.  The things are a bit complicated
 399    due to need to handle subregs and extends.  The value of the object described
 400    by it can be obtained as follows (all computations are done in extend_mode):
 401
 402    Value in i-th iteration is
 403      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 404
 405    If first_special is true, the value in the first iteration is
 406      delta + mult * base
 407
 408    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 409      subreg_{mode} (base + i * step)
 410
 411    The get_iv_value function can be used to obtain these expressions.
 412
 413    ??? Add a third mode field that would specify the mode in that inner
 414    computation is done, which would enable it to be different from the
 415    outer one?  */
 416
 417 struct rtx_iv
 418 {
 419   /* Its base and step (mode of base and step is supposed to be extend_mode,
 420      see the description above).  */
 421   rtx base, step;
 422
 423   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 424      or IV_UNKNOWN_EXTEND).  */
 425   enum iv_extend_code extend;
 426
 427   /* Operations applied in the extended mode.  */
 428   rtx delta, mult;
 429
 430   /* The mode it is extended to.  */
 431   scalar_int_mode extend_mode;
 432
 433   /* The mode the variable iterates in.  */
 434   scalar_int_mode mode;
 435
 436   /* Whether the first iteration needs to be handled specially.  */
 437   unsigned first_special : 1;
 438 };
 439
 440 /* The description of an exit from the loop and of the number of iterations
 441    till we take the exit.  */
 442
 443 struct GTY(()) niter_desc
 444 {
 445   /* The edge out of the loop.  */
 446   edge out_edge;
 447
 448   /* The other edge leading from the condition.  */
 449   edge in_edge;
 450
 451   /* True if we are able to say anything about number of iterations of the
 452      loop.  */
 453   bool simple_p;
 454
 455   /* True if the loop iterates the constant number of times.  */
 456   bool const_iter;
 457
 458   /* Number of iterations if constant.  */
 459   uint64_t niter;
 460
 461   /* Assumptions under that the rest of the information is valid.  */
 462   rtx assumptions;
 463
 464   /* Assumptions under that the loop ends before reaching the latch,
 465      even if value of niter_expr says otherwise.  */
 466   rtx noloop_assumptions;
 467
 468   /* Condition under that the loop is infinite.  */
 469   rtx infinite;
 470
 471   /* Whether the comparison is signed.  */
 472   bool signed_p;
 473
 474   /* The mode in that niter_expr should be computed.  */
 475   scalar_int_mode mode;
 476
 477   /* The number of iterations of the loop.  */
 478   rtx niter_expr;
 479 };
 480
 481 extern void iv_analysis_loop_init (struct loop *);
 482 extern bool iv_analyze (rtx_insn *, scalar_int_mode, rtx, struct rtx_iv *);
 483 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 484 extern bool iv_analyze_expr (rtx_insn *, scalar_int_mode, rtx,
 485                              struct rtx_iv *);
 486 extern rtx get_iv_value (struct rtx_iv *, rtx);
 487 extern bool biv_p (rtx_insn *, scalar_int_mode, rtx);
 488 extern void find_simple_exit (struct loop *, struct niter_desc *);
 489 extern void iv_analysis_done (void);
 490
 491 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 492 extern void free_simple_loop_desc (struct loop *loop);
 493
 494 static inline struct niter_desc *
 495 simple_loop_desc (struct loop *loop)
 496 {
 497   return loop->simple_loop_desc;
 498 }
 499
 500 /* Accessors for the loop structures.  */
 501
 502 /* Returns the loop with index NUM from FNs loop tree.  */
 503
 504 static inline struct loop *
 505 get_loop (struct function *fn, unsigned num)
 506 {
 507   return (*loops_for_fn (fn)->larray)[num];
 508 }
 509
 510 /* Returns the number of superloops of LOOP.  */
 511
 512 static inline unsigned
 513 loop_depth (const struct loop *loop)
 514 {
 515   return vec_safe_length (loop->superloops);
 516 }
 517
 518 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 519    loop.  */
 520
 521 static inline struct loop *
 522 loop_outer (const struct loop *loop)
 523 {
 524   unsigned n = vec_safe_length (loop->superloops);
 525
 526   if (n == 0)
 527     return NULL;
 528
 529   return (*loop->superloops)[n - 1];
 530 }
 531
 532 /* Returns true if LOOP has at least one exit edge.  */
 533
 534 static inline bool
 535 loop_has_exit_edges (const struct loop *loop)
 536 {
 537   return loop->exits->next->e != NULL;
 538 }
 539
 540 /* Returns the list of loops in FN.  */
 541
 542 inline vec<loop_p, va_gc> *
 543 get_loops (struct function *fn)
 544 {
 545   struct loops *loops = loops_for_fn (fn);
 546   if (!loops)
 547     return NULL;
 548
 549   return loops->larray;
 550 }
 551
 552 /* Returns the number of loops in FN (including the removed
 553    ones and the fake loop that forms the root of the loop tree).  */
 554
 555 static inline unsigned
 556 number_of_loops (struct function *fn)
 557 {
 558   struct loops *loops = loops_for_fn (fn);
 559   if (!loops)
 560     return 0;
 561
 562   return vec_safe_length (loops->larray);
 563 }
 564
 565 /* Returns true if state of the loops satisfies all properties
 566    described by FLAGS.  */
 567
 568 static inline bool
 569 loops_state_satisfies_p (function *fn, unsigned flags)
 570 {
 571   return (loops_for_fn (fn)->state & flags) == flags;
 572 }
 573
 574 static inline bool
 575 loops_state_satisfies_p (unsigned flags)
 576 {
 577   return loops_state_satisfies_p (cfun, flags);
 578 }
 579
 580 /* Sets FLAGS to the loops state.  */
 581
 582 static inline void
 583 loops_state_set (function *fn, unsigned flags)
 584 {
 585   loops_for_fn (fn)->state |= flags;
 586 }
 587
 588 static inline void
 589 loops_state_set (unsigned flags)
 590 {
 591   loops_state_set (cfun, flags);
 592 }
 593
 594 /* Clears FLAGS from the loops state.  */
 595
 596 static inline void
 597 loops_state_clear (function *fn, unsigned flags)
 598 {
 599   loops_for_fn (fn)->state &= ~flags;
 600 }
 601
 602 static inline void
 603 loops_state_clear (unsigned flags)
 604 {
 605   if (!current_loops)
 606     return;
 607   loops_state_clear (cfun, flags);
 608 }
 609
 610 /* Check loop structure invariants, if internal consistency checks are
 611    enabled.  */
 612
 613 static inline void
 614 checking_verify_loop_structure (void)
 615 {
 616   /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
 617
 618      The loop optimizers should never make changes to the CFG which
 619      require loop fixups.  But the low level CFG manipulation code may
 620      set the flag conservatively.
 621
 622      Go ahead and clear the flag here.  That avoids the assert inside
 623      VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
 624      structures VERIFY_LOOP_STRUCTURE will detect it.
 625
 626      This also avoid the compile time cost of excessive fixups.  */
 627   loops_state_clear (LOOPS_NEED_FIXUP);
 628   if (flag_checking)
 629     verify_loop_structure ();
 630 }
 631
 632 /* Loop iterators.  */
 633
 634 /* Flags for loop iteration.  */
 635
 636 enum li_flags
 637 {
 638   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 639   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 640                                    starting from innermost ones.  */
 641   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 642 };
 643
 644 /* The iterator for loops.  */
 645
 646 struct loop_iterator
 647 {
 648   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 649   ~loop_iterator ();
 650
 651   inline loop_p next ();
 652
 653   /* The function we are visiting.  */
 654   function *fn;
 655
 656   /* The list of loops to visit.  */
 657   vec<int> to_visit;
 658
 659   /* The index of the actual loop.  */
 660   unsigned idx;
 661 };
 662
 663 inline loop_p
 664 loop_iterator::next ()
 665 {
 666   int anum;
 667
 668   while (this->to_visit.iterate (this->idx, &anum))
 669     {
 670       this->idx++;
 671       loop_p loop = get_loop (fn, anum);
 672       if (loop)
 673         return loop;
 674     }
 675
 676   return NULL;
 677 }
 678
 679 inline
 680 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 681 {
 682   struct loop *aloop;
 683   unsigned i;
 684   int mn;
 685
 686   this->idx = 0;
 687   this->fn = fn;
 688   if (!loops_for_fn (fn))
 689     {
 690       this->to_visit.create (0);
 691       *loop = NULL;
 692       return;
 693     }
 694
 695   this->to_visit.create (number_of_loops (fn));
 696   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 697
 698   if (flags & LI_ONLY_INNERMOST)
 699     {
 700       for (i = 0; vec_safe_iterate (loops_for_fn (fn)->larray, i, &aloop); i++)
 701         if (aloop != NULL
 702             && aloop->inner == NULL
 703             && aloop->num >= mn)
 704           this->to_visit.quick_push (aloop->num);
 705     }
 706   else if (flags & LI_FROM_INNERMOST)
 707     {
 708       /* Push the loops to LI->TO_VISIT in postorder.  */
 709       for (aloop = loops_for_fn (fn)->tree_root;
 710            aloop->inner != NULL;
 711            aloop = aloop->inner)
 712         continue;
 713
 714       while (1)
 715         {
 716           if (aloop->num >= mn)
 717             this->to_visit.quick_push (aloop->num);
 718
 719           if (aloop->next)
 720             {
 721               for (aloop = aloop->next;
 722                    aloop->inner != NULL;
 723                    aloop = aloop->inner)
 724                 continue;
 725             }
 726           else if (!loop_outer (aloop))
 727             break;
 728           else
 729             aloop = loop_outer (aloop);
 730         }
 731     }
 732   else
 733     {
 734       /* Push the loops to LI->TO_VISIT in preorder.  */
 735       aloop = loops_for_fn (fn)->tree_root;
 736       while (1)
 737         {
 738           if (aloop->num >= mn)
 739             this->to_visit.quick_push (aloop->num);
 740
 741           if (aloop->inner != NULL)
 742             aloop = aloop->inner;
 743           else
 744             {
 745               while (aloop != NULL && aloop->next == NULL)
 746                 aloop = loop_outer (aloop);
 747               if (aloop == NULL)
 748                 break;
 749               aloop = aloop->next;
 750             }
 751         }
 752     }
 753
 754   *loop = this->next ();
 755 }
 756
 757 inline
 758 loop_iterator::~loop_iterator ()
 759 {
 760   this->to_visit.release ();
 761 }
 762
 763 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 764   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 765        (LOOP); \
 766        (LOOP) = li.next ())
 767
 768 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 769   for (loop_iterator li(FN, &(LOOP), FLAGS); \
 770        (LOOP); \
 771        (LOOP) = li.next ())
 772
 773 /* The properties of the target.  */
 774 struct target_cfgloop {
 775   /* Number of available registers.  */
 776   unsigned x_target_avail_regs;
 777
 778   /* Number of available registers that are call-clobbered.  */
 779   unsigned x_target_clobbered_regs;
 780
 781   /* Number of registers reserved for temporary expressions.  */
 782   unsigned x_target_res_regs;
 783
 784   /* The cost for register when there still is some reserve, but we are
 785      approaching the number of available registers.  */
 786   unsigned x_target_reg_cost[2];
 787
 788   /* The cost for register when we need to spill.  */
 789   unsigned x_target_spill_cost[2];
 790 };
 791
 792 extern struct target_cfgloop default_target_cfgloop;
 793 #if SWITCHABLE_TARGET
 794 extern struct target_cfgloop *this_target_cfgloop;
 795 #else
 796 #define this_target_cfgloop (&default_target_cfgloop)
 797 #endif
 798
 799 #define target_avail_regs \
 800   (this_target_cfgloop->x_target_avail_regs)
 801 #define target_clobbered_regs \
 802   (this_target_cfgloop->x_target_clobbered_regs)
 803 #define target_res_regs \
 804   (this_target_cfgloop->x_target_res_regs)
 805 #define target_reg_cost \
 806   (this_target_cfgloop->x_target_reg_cost)
 807 #define target_spill_cost \
 808   (this_target_cfgloop->x_target_spill_cost)
 809
 810 /* Register pressure estimation for induction variable optimizations & loop
 811    invariant motion.  */
 812 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 813 extern void init_set_costs (void);
 814
 815 /* Loop optimizer initialization.  */
 816 extern void loop_optimizer_init (unsigned);
 817 extern void loop_optimizer_finalize (function *);
 818 inline void
 819 loop_optimizer_finalize ()
 820 {
 821   loop_optimizer_finalize (cfun);
 822 }
 823
 824 /* Optimization passes.  */
 825 enum
 826 {
 827   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 828   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 829 };
 830
 831 extern void doloop_optimize_loops (void);
 832 extern void move_loop_invariants (void);
 833 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 834
 835 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 836 static inline struct loop *
 837 loop_outermost (struct loop *loop)
 838 {
 839   unsigned n = vec_safe_length (loop->superloops);
 840
 841   if (n <= 1)
 842     return loop;
 843
 844   return (*loop->superloops)[1];
 845 }
 846
 847 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 848 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 849 extern HOST_WIDE_INT get_max_loop_iterations_int (const struct loop *);
 850 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (struct loop *);
 851 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 852 extern bool get_max_loop_iterations (const struct loop *loop, widest_int *nit);
 853 extern bool get_likely_max_loop_iterations (struct loop *loop, widest_int *nit);
 854 extern int bb_loop_depth (const_basic_block);
 855
 856 /* Converts VAL to widest_int.  */
 857
 858 static inline widest_int
 859 gcov_type_to_wide_int (gcov_type val)
 860 {
 861   HOST_WIDE_INT a[2];
 862
 863   a[0] = (unsigned HOST_WIDE_INT) val;
 864   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 865      the size of type.  */
 866   val >>= HOST_BITS_PER_WIDE_INT - 1;
 867   val >>= 1;
 868   a[1] = (unsigned HOST_WIDE_INT) val;
 869
 870   return widest_int::from_array (a, 2);
 871 }
 872 #endif /* GCC_CFGLOOP_H */