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                                      struct loop * = NULL);
 347 extern void flow_loop_tree_node_remove (struct loop *);
 348 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 349 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 350 extern struct loop * find_common_loop (struct loop *, struct loop *);
 351 struct loop *superloop_at_depth (struct loop *, unsigned);
 352 struct eni_weights;
 353 extern int num_loop_insns (const struct loop *);
 354 extern int average_num_loop_insns (const struct loop *);
 355 extern unsigned get_loop_level (const struct loop *);
 356 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 357 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 358 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 359 extern void mark_loop_exit_edges (void);
 360 extern location_t get_loop_location (struct loop *loop);
 361
 362 /* Loops & cfg manipulation.  */
 363 extern basic_block *get_loop_body (const struct loop *);
 364 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 365                                          unsigned);
 366 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 367 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 368 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 369                                int (*) (const void *, const void *));
 370
 371 extern vec<edge> get_loop_exit_edges (const struct loop *);
 372 extern edge single_exit (const struct loop *);
 373 extern edge single_likely_exit (struct loop *loop);
 374 extern unsigned num_loop_branches (const struct loop *);
 375
 376 extern edge loop_preheader_edge (const struct loop *);
 377 extern edge loop_latch_edge (const struct loop *);
 378
 379 extern void add_bb_to_loop (basic_block, struct loop *);
 380 extern void remove_bb_from_loops (basic_block);
 381
 382 extern void cancel_loop_tree (struct loop *);
 383 extern void delete_loop (struct loop *);
 384
 385
 386 extern void verify_loop_structure (void);
 387
 388 /* Loop analysis.  */
 389 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 390 gcov_type expected_loop_iterations_unbounded (const struct loop *,
 391                                               bool *read_profile_p = NULL);
 392 extern unsigned expected_loop_iterations (struct loop *);
 393 extern rtx doloop_condition_get (rtx_insn *);
 394
 395 void mark_loop_for_removal (loop_p);
 396
 397 /* Induction variable analysis.  */
 398
 399 /* The description of induction variable.  The things are a bit complicated
 400    due to need to handle subregs and extends.  The value of the object described
 401    by it can be obtained as follows (all computations are done in extend_mode):
 402
 403    Value in i-th iteration is
 404      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 405
 406    If first_special is true, the value in the first iteration is
 407      delta + mult * base
 408
 409    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 410      subreg_{mode} (base + i * step)
 411
 412    The get_iv_value function can be used to obtain these expressions.
 413
 414    ??? Add a third mode field that would specify the mode in that inner
 415    computation is done, which would enable it to be different from the
 416    outer one?  */
 417
 418 struct rtx_iv
 419 {
 420   /* Its base and step (mode of base and step is supposed to be extend_mode,
 421      see the description above).  */
 422   rtx base, step;
 423
 424   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 425      or IV_UNKNOWN_EXTEND).  */
 426   enum iv_extend_code extend;
 427
 428   /* Operations applied in the extended mode.  */
 429   rtx delta, mult;
 430
 431   /* The mode it is extended to.  */
 432   scalar_int_mode extend_mode;
 433
 434   /* The mode the variable iterates in.  */
 435   scalar_int_mode mode;
 436
 437   /* Whether the first iteration needs to be handled specially.  */
 438   unsigned first_special : 1;
 439 };
 440
 441 /* The description of an exit from the loop and of the number of iterations
 442    till we take the exit.  */
 443
 444 struct GTY(()) niter_desc
 445 {
 446   /* The edge out of the loop.  */
 447   edge out_edge;
 448
 449   /* The other edge leading from the condition.  */
 450   edge in_edge;
 451
 452   /* True if we are able to say anything about number of iterations of the
 453      loop.  */
 454   bool simple_p;
 455
 456   /* True if the loop iterates the constant number of times.  */
 457   bool const_iter;
 458
 459   /* Number of iterations if constant.  */
 460   uint64_t niter;
 461
 462   /* Assumptions under that the rest of the information is valid.  */
 463   rtx assumptions;
 464
 465   /* Assumptions under that the loop ends before reaching the latch,
 466      even if value of niter_expr says otherwise.  */
 467   rtx noloop_assumptions;
 468
 469   /* Condition under that the loop is infinite.  */
 470   rtx infinite;
 471
 472   /* Whether the comparison is signed.  */
 473   bool signed_p;
 474
 475   /* The mode in that niter_expr should be computed.  */
 476   scalar_int_mode mode;
 477
 478   /* The number of iterations of the loop.  */
 479   rtx niter_expr;
 480 };
 481
 482 extern void iv_analysis_loop_init (struct loop *);
 483 extern bool iv_analyze (rtx_insn *, scalar_int_mode, rtx, struct rtx_iv *);
 484 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 485 extern bool iv_analyze_expr (rtx_insn *, scalar_int_mode, rtx,
 486                              struct rtx_iv *);
 487 extern rtx get_iv_value (struct rtx_iv *, rtx);
 488 extern bool biv_p (rtx_insn *, scalar_int_mode, rtx);
 489 extern void find_simple_exit (struct loop *, struct niter_desc *);
 490 extern void iv_analysis_done (void);
 491
 492 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 493 extern void free_simple_loop_desc (struct loop *loop);
 494
 495 static inline struct niter_desc *
 496 simple_loop_desc (struct loop *loop)
 497 {
 498   return loop->simple_loop_desc;
 499 }
 500
 501 /* Accessors for the loop structures.  */
 502
 503 /* Returns the loop with index NUM from FNs loop tree.  */
 504
 505 static inline struct loop *
 506 get_loop (struct function *fn, unsigned num)
 507 {
 508   return (*loops_for_fn (fn)->larray)[num];
 509 }
 510
 511 /* Returns the number of superloops of LOOP.  */
 512
 513 static inline unsigned
 514 loop_depth (const struct loop *loop)
 515 {
 516   return vec_safe_length (loop->superloops);
 517 }
 518
 519 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 520    loop.  */
 521
 522 static inline struct loop *
 523 loop_outer (const struct loop *loop)
 524 {
 525   unsigned n = vec_safe_length (loop->superloops);
 526
 527   if (n == 0)
 528     return NULL;
 529
 530   return (*loop->superloops)[n - 1];
 531 }
 532
 533 /* Returns true if LOOP has at least one exit edge.  */
 534
 535 static inline bool
 536 loop_has_exit_edges (const struct loop *loop)
 537 {
 538   return loop->exits->next->e != NULL;
 539 }
 540
 541 /* Returns the list of loops in FN.  */
 542
 543 inline vec<loop_p, va_gc> *
 544 get_loops (struct function *fn)
 545 {
 546   struct loops *loops = loops_for_fn (fn);
 547   if (!loops)
 548     return NULL;
 549
 550   return loops->larray;
 551 }
 552
 553 /* Returns the number of loops in FN (including the removed
 554    ones and the fake loop that forms the root of the loop tree).  */
 555
 556 static inline unsigned
 557 number_of_loops (struct function *fn)
 558 {
 559   struct loops *loops = loops_for_fn (fn);
 560   if (!loops)
 561     return 0;
 562
 563   return vec_safe_length (loops->larray);
 564 }
 565
 566 /* Returns true if state of the loops satisfies all properties
 567    described by FLAGS.  */
 568
 569 static inline bool
 570 loops_state_satisfies_p (function *fn, unsigned flags)
 571 {
 572   return (loops_for_fn (fn)->state & flags) == flags;
 573 }
 574
 575 static inline bool
 576 loops_state_satisfies_p (unsigned flags)
 577 {
 578   return loops_state_satisfies_p (cfun, flags);
 579 }
 580
 581 /* Sets FLAGS to the loops state.  */
 582
 583 static inline void
 584 loops_state_set (function *fn, unsigned flags)
 585 {
 586   loops_for_fn (fn)->state |= flags;
 587 }
 588
 589 static inline void
 590 loops_state_set (unsigned flags)
 591 {
 592   loops_state_set (cfun, flags);
 593 }
 594
 595 /* Clears FLAGS from the loops state.  */
 596
 597 static inline void
 598 loops_state_clear (function *fn, unsigned flags)
 599 {
 600   loops_for_fn (fn)->state &= ~flags;
 601 }
 602
 603 static inline void
 604 loops_state_clear (unsigned flags)
 605 {
 606   if (!current_loops)
 607     return;
 608   loops_state_clear (cfun, flags);
 609 }
 610
 611 /* Check loop structure invariants, if internal consistency checks are
 612    enabled.  */
 613
 614 static inline void
 615 checking_verify_loop_structure (void)
 616 {
 617   /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
 618
 619      The loop optimizers should never make changes to the CFG which
 620      require loop fixups.  But the low level CFG manipulation code may
 621      set the flag conservatively.
 622
 623      Go ahead and clear the flag here.  That avoids the assert inside
 624      VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
 625      structures VERIFY_LOOP_STRUCTURE will detect it.
 626
 627      This also avoid the compile time cost of excessive fixups.  */
 628   loops_state_clear (LOOPS_NEED_FIXUP);
 629   if (flag_checking)
 630     verify_loop_structure ();
 631 }
 632
 633 /* Loop iterators.  */
 634
 635 /* Flags for loop iteration.  */
 636
 637 enum li_flags
 638 {
 639   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 640   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 641                                    starting from innermost ones.  */
 642   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 643 };
 644
 645 /* The iterator for loops.  */
 646
 647 struct loop_iterator
 648 {
 649   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 650   ~loop_iterator ();
 651
 652   inline loop_p next ();
 653
 654   /* The function we are visiting.  */
 655   function *fn;
 656
 657   /* The list of loops to visit.  */
 658   vec<int> to_visit;
 659
 660   /* The index of the actual loop.  */
 661   unsigned idx;
 662 };
 663
 664 inline loop_p
 665 loop_iterator::next ()
 666 {
 667   int anum;
 668
 669   while (this->to_visit.iterate (this->idx, &anum))
 670     {
 671       this->idx++;
 672       loop_p loop = get_loop (fn, anum);
 673       if (loop)
 674         return loop;
 675     }
 676
 677   return NULL;
 678 }
 679
 680 inline
 681 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 682 {
 683   struct loop *aloop;
 684   unsigned i;
 685   int mn;
 686
 687   this->idx = 0;
 688   this->fn = fn;
 689   if (!loops_for_fn (fn))
 690     {
 691       this->to_visit.create (0);
 692       *loop = NULL;
 693       return;
 694     }
 695
 696   this->to_visit.create (number_of_loops (fn));
 697   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 698
 699   if (flags & LI_ONLY_INNERMOST)
 700     {
 701       for (i = 0; vec_safe_iterate (loops_for_fn (fn)->larray, i, &aloop); i++)
 702         if (aloop != NULL
 703             && aloop->inner == NULL
 704             && aloop->num >= mn)
 705           this->to_visit.quick_push (aloop->num);
 706     }
 707   else if (flags & LI_FROM_INNERMOST)
 708     {
 709       /* Push the loops to LI->TO_VISIT in postorder.  */
 710       for (aloop = loops_for_fn (fn)->tree_root;
 711            aloop->inner != NULL;
 712            aloop = aloop->inner)
 713         continue;
 714
 715       while (1)
 716         {
 717           if (aloop->num >= mn)
 718             this->to_visit.quick_push (aloop->num);
 719
 720           if (aloop->next)
 721             {
 722               for (aloop = aloop->next;
 723                    aloop->inner != NULL;
 724                    aloop = aloop->inner)
 725                 continue;
 726             }
 727           else if (!loop_outer (aloop))
 728             break;
 729           else
 730             aloop = loop_outer (aloop);
 731         }
 732     }
 733   else
 734     {
 735       /* Push the loops to LI->TO_VISIT in preorder.  */
 736       aloop = loops_for_fn (fn)->tree_root;
 737       while (1)
 738         {
 739           if (aloop->num >= mn)
 740             this->to_visit.quick_push (aloop->num);
 741
 742           if (aloop->inner != NULL)
 743             aloop = aloop->inner;
 744           else
 745             {
 746               while (aloop != NULL && aloop->next == NULL)
 747                 aloop = loop_outer (aloop);
 748               if (aloop == NULL)
 749                 break;
 750               aloop = aloop->next;
 751             }
 752         }
 753     }
 754
 755   *loop = this->next ();
 756 }
 757
 758 inline
 759 loop_iterator::~loop_iterator ()
 760 {
 761   this->to_visit.release ();
 762 }
 763
 764 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 765   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 766        (LOOP); \
 767        (LOOP) = li.next ())
 768
 769 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 770   for (loop_iterator li(FN, &(LOOP), FLAGS); \
 771        (LOOP); \
 772        (LOOP) = li.next ())
 773
 774 /* The properties of the target.  */
 775 struct target_cfgloop {
 776   /* Number of available registers.  */
 777   unsigned x_target_avail_regs;
 778
 779   /* Number of available registers that are call-clobbered.  */
 780   unsigned x_target_clobbered_regs;
 781
 782   /* Number of registers reserved for temporary expressions.  */
 783   unsigned x_target_res_regs;
 784
 785   /* The cost for register when there still is some reserve, but we are
 786      approaching the number of available registers.  */
 787   unsigned x_target_reg_cost[2];
 788
 789   /* The cost for register when we need to spill.  */
 790   unsigned x_target_spill_cost[2];
 791 };
 792
 793 extern struct target_cfgloop default_target_cfgloop;
 794 #if SWITCHABLE_TARGET
 795 extern struct target_cfgloop *this_target_cfgloop;
 796 #else
 797 #define this_target_cfgloop (&default_target_cfgloop)
 798 #endif
 799
 800 #define target_avail_regs \
 801   (this_target_cfgloop->x_target_avail_regs)
 802 #define target_clobbered_regs \
 803   (this_target_cfgloop->x_target_clobbered_regs)
 804 #define target_res_regs \
 805   (this_target_cfgloop->x_target_res_regs)
 806 #define target_reg_cost \
 807   (this_target_cfgloop->x_target_reg_cost)
 808 #define target_spill_cost \
 809   (this_target_cfgloop->x_target_spill_cost)
 810
 811 /* Register pressure estimation for induction variable optimizations & loop
 812    invariant motion.  */
 813 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 814 extern void init_set_costs (void);
 815
 816 /* Loop optimizer initialization.  */
 817 extern void loop_optimizer_init (unsigned);
 818 extern void loop_optimizer_finalize (function *);
 819 inline void
 820 loop_optimizer_finalize ()
 821 {
 822   loop_optimizer_finalize (cfun);
 823 }
 824
 825 /* Optimization passes.  */
 826 enum
 827 {
 828   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 829   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 830 };
 831
 832 extern void doloop_optimize_loops (void);
 833 extern void move_loop_invariants (void);
 834 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 835
 836 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 837 static inline struct loop *
 838 loop_outermost (struct loop *loop)
 839 {
 840   unsigned n = vec_safe_length (loop->superloops);
 841
 842   if (n <= 1)
 843     return loop;
 844
 845   return (*loop->superloops)[1];
 846 }
 847
 848 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 849 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 850 extern HOST_WIDE_INT get_max_loop_iterations_int (const struct loop *);
 851 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (struct loop *);
 852 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 853 extern bool get_max_loop_iterations (const struct loop *loop, widest_int *nit);
 854 extern bool get_likely_max_loop_iterations (struct loop *loop, widest_int *nit);
 855 extern int bb_loop_depth (const_basic_block);
 856
 857 /* Converts VAL to widest_int.  */
 858
 859 static inline widest_int
 860 gcov_type_to_wide_int (gcov_type val)
 861 {
 862   HOST_WIDE_INT a[2];
 863
 864   a[0] = (unsigned HOST_WIDE_INT) val;
 865   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 866      the size of type.  */
 867   val >>= HOST_BITS_PER_WIDE_INT - 1;
 868   val >>= 1;
 869   a[1] = (unsigned HOST_WIDE_INT) val;
 870
 871   return widest_int::from_array (a, 2);
 872 }
 873 #endif /* GCC_CFGLOOP_H */