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
 225      given, just do what we always do.  A value of 1, means don't unroll
 226      the loop.  */
 227   unsigned short unroll;
 228
 229   /* For SIMD loops, this is a unique identifier of the loop, referenced
 230      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 231      builtins.  */
 232   tree simduid;
 233
 234   /* In loop optimization, it's common to generate loops from the original
 235      loop.  This field records the index of the original loop which can be
 236      used to track the original loop from newly generated loops.  This can
 237      be done by calling function get_loop (cfun, orig_loop_num).  Note the
 238      original loop could be destroyed for various reasons thus no longer
 239      exists, as a result, function call to get_loop returns NULL pointer.
 240      In this case, this field should not be used and needs to be cleared
 241      whenever possible.  */
 242   int orig_loop_num;
 243
 244   /* Upper bound on number of iterations of a loop.  */
 245   struct nb_iter_bound *bounds;
 246
 247   /* Non-overflow control ivs of a loop.  */
 248   struct control_iv *control_ivs;
 249
 250   /* Head of the cyclic list of the exits of the loop.  */
 251   struct loop_exit *exits;
 252
 253   /* Number of iteration analysis data for RTL.  */
 254   struct niter_desc *simple_loop_desc;
 255
 256   /* For sanity checking during loop fixup we record here the former
 257      loop header for loops marked for removal.  Note that this prevents
 258      the basic-block from being collected but its index can still be
 259      reused.  */
 260   basic_block former_header;
 261 };
 262
 263 /* Set if the loop is known to be infinite.  */
 264 #define LOOP_C_INFINITE         (1 << 0)
 265 /* Set if the loop is known to be finite without any assumptions.  */
 266 #define LOOP_C_FINITE           (1 << 1)
 267
 268 /* Set C to the LOOP constraint.  */
 269 static inline void
 270 loop_constraint_set (struct loop *loop, unsigned c)
 271 {
 272   loop->constraints |= c;
 273 }
 274
 275 /* Clear C from the LOOP constraint.  */
 276 static inline void
 277 loop_constraint_clear (struct loop *loop, unsigned c)
 278 {
 279   loop->constraints &= ~c;
 280 }
 281
 282 /* Check if C is set in the LOOP constraint.  */
 283 static inline bool
 284 loop_constraint_set_p (struct loop *loop, unsigned c)
 285 {
 286   return (loop->constraints & c) == c;
 287 }
 288
 289 /* Flags for state of loop structure.  */
 290 enum
 291 {
 292   LOOPS_HAVE_PREHEADERS = 1,
 293   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 294   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 295   LOOPS_HAVE_RECORDED_EXITS = 8,
 296   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 297   LOOP_CLOSED_SSA = 32,
 298   LOOPS_NEED_FIXUP = 64,
 299   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 300 };
 301
 302 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 303                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 304 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 305
 306 /* Structure to hold CFG information about natural loops within a function.  */
 307 struct GTY (()) loops {
 308   /* State of loops.  */
 309   int state;
 310
 311   /* Array of the loops.  */
 312   vec<loop_p, va_gc> *larray;
 313
 314   /* Maps edges to the list of their descriptions as loop exits.  Edges
 315      whose sources or destinations have loop_father == NULL (which may
 316      happen during the cfg manipulations) should not appear in EXITS.  */
 317   hash_table<loop_exit_hasher> *GTY(()) exits;
 318
 319   /* Pointer to root of loop hierarchy tree.  */
 320   struct loop *tree_root;
 321 };
 322
 323 /* Loop recognition.  */
 324 bool bb_loop_header_p (basic_block);
 325 void init_loops_structure (struct function *, struct loops *, unsigned);
 326 extern struct loops *flow_loops_find (struct loops *);
 327 extern void disambiguate_loops_with_multiple_latches (void);
 328 extern void flow_loops_free (struct loops *);
 329 extern void flow_loops_dump (FILE *,
 330                              void (*)(const struct loop *, FILE *, int), int);
 331 extern void flow_loop_dump (const struct loop *, FILE *,
 332                             void (*)(const struct loop *, FILE *, int), int);
 333 struct loop *alloc_loop (void);
 334 extern void flow_loop_free (struct loop *);
 335 int flow_loop_nodes_find (basic_block, struct loop *);
 336 unsigned fix_loop_structure (bitmap changed_bbs);
 337 bool mark_irreducible_loops (void);
 338 void release_recorded_exits (function *);
 339 void record_loop_exits (void);
 340 void rescan_loop_exit (edge, bool, bool);
 341 void sort_sibling_loops (function *);
 342
 343 /* Loop data structure manipulation/querying.  */
 344 extern void flow_loop_tree_node_add (struct loop *, struct loop *);
 345 extern void flow_loop_tree_node_remove (struct loop *);
 346 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 347 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 348 extern struct loop * find_common_loop (struct loop *, struct loop *);
 349 struct loop *superloop_at_depth (struct loop *, unsigned);
 350 struct eni_weights;
 351 extern int num_loop_insns (const struct loop *);
 352 extern int average_num_loop_insns (const struct loop *);
 353 extern unsigned get_loop_level (const struct loop *);
 354 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 355 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 356 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 357 extern void mark_loop_exit_edges (void);
 358 extern location_t get_loop_location (struct loop *loop);
 359
 360 /* Loops & cfg manipulation.  */
 361 extern basic_block *get_loop_body (const struct loop *);
 362 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 363                                          unsigned);
 364 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 365 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 366 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 367                                int (*) (const void *, const void *));
 368
 369 extern vec<edge> get_loop_exit_edges (const struct loop *);
 370 extern edge single_exit (const struct loop *);
 371 extern edge single_likely_exit (struct loop *loop);
 372 extern unsigned num_loop_branches (const struct loop *);
 373
 374 extern edge loop_preheader_edge (const struct loop *);
 375 extern edge loop_latch_edge (const struct loop *);
 376
 377 extern void add_bb_to_loop (basic_block, struct loop *);
 378 extern void remove_bb_from_loops (basic_block);
 379
 380 extern void cancel_loop_tree (struct loop *);
 381 extern void delete_loop (struct loop *);
 382
 383
 384 extern void verify_loop_structure (void);
 385
 386 /* Loop analysis.  */
 387 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 388 gcov_type expected_loop_iterations_unbounded (const struct loop *,
 389                                               bool *read_profile_p = NULL);
 390 extern unsigned expected_loop_iterations (struct loop *);
 391 extern rtx doloop_condition_get (rtx_insn *);
 392
 393 void mark_loop_for_removal (loop_p);
 394
 395 /* Induction variable analysis.  */
 396
 397 /* The description of induction variable.  The things are a bit complicated
 398    due to need to handle subregs and extends.  The value of the object described
 399    by it can be obtained as follows (all computations are done in extend_mode):
 400
 401    Value in i-th iteration is
 402      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 403
 404    If first_special is true, the value in the first iteration is
 405      delta + mult * base
 406
 407    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 408      subreg_{mode} (base + i * step)
 409
 410    The get_iv_value function can be used to obtain these expressions.
 411
 412    ??? Add a third mode field that would specify the mode in that inner
 413    computation is done, which would enable it to be different from the
 414    outer one?  */
 415
 416 struct rtx_iv
 417 {
 418   /* Its base and step (mode of base and step is supposed to be extend_mode,
 419      see the description above).  */
 420   rtx base, step;
 421
 422   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 423      or IV_UNKNOWN_EXTEND).  */
 424   enum iv_extend_code extend;
 425
 426   /* Operations applied in the extended mode.  */
 427   rtx delta, mult;
 428
 429   /* The mode it is extended to.  */
 430   scalar_int_mode extend_mode;
 431
 432   /* The mode the variable iterates in.  */
 433   scalar_int_mode mode;
 434
 435   /* Whether the first iteration needs to be handled specially.  */
 436   unsigned first_special : 1;
 437 };
 438
 439 /* The description of an exit from the loop and of the number of iterations
 440    till we take the exit.  */
 441
 442 struct GTY(()) niter_desc
 443 {
 444   /* The edge out of the loop.  */
 445   edge out_edge;
 446
 447   /* The other edge leading from the condition.  */
 448   edge in_edge;
 449
 450   /* True if we are able to say anything about number of iterations of the
 451      loop.  */
 452   bool simple_p;
 453
 454   /* True if the loop iterates the constant number of times.  */
 455   bool const_iter;
 456
 457   /* Number of iterations if constant.  */
 458   uint64_t niter;
 459
 460   /* Assumptions under that the rest of the information is valid.  */
 461   rtx assumptions;
 462
 463   /* Assumptions under that the loop ends before reaching the latch,
 464      even if value of niter_expr says otherwise.  */
 465   rtx noloop_assumptions;
 466
 467   /* Condition under that the loop is infinite.  */
 468   rtx infinite;
 469
 470   /* Whether the comparison is signed.  */
 471   bool signed_p;
 472
 473   /* The mode in that niter_expr should be computed.  */
 474   scalar_int_mode mode;
 475
 476   /* The number of iterations of the loop.  */
 477   rtx niter_expr;
 478 };
 479
 480 extern void iv_analysis_loop_init (struct loop *);
 481 extern bool iv_analyze (rtx_insn *, scalar_int_mode, rtx, struct rtx_iv *);
 482 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 483 extern bool iv_analyze_expr (rtx_insn *, scalar_int_mode, rtx,
 484                              struct rtx_iv *);
 485 extern rtx get_iv_value (struct rtx_iv *, rtx);
 486 extern bool biv_p (rtx_insn *, scalar_int_mode, rtx);
 487 extern void find_simple_exit (struct loop *, struct niter_desc *);
 488 extern void iv_analysis_done (void);
 489
 490 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 491 extern void free_simple_loop_desc (struct loop *loop);
 492
 493 static inline struct niter_desc *
 494 simple_loop_desc (struct loop *loop)
 495 {
 496   return loop->simple_loop_desc;
 497 }
 498
 499 /* Accessors for the loop structures.  */
 500
 501 /* Returns the loop with index NUM from FNs loop tree.  */
 502
 503 static inline struct loop *
 504 get_loop (struct function *fn, unsigned num)
 505 {
 506   return (*loops_for_fn (fn)->larray)[num];
 507 }
 508
 509 /* Returns the number of superloops of LOOP.  */
 510
 511 static inline unsigned
 512 loop_depth (const struct loop *loop)
 513 {
 514   return vec_safe_length (loop->superloops);
 515 }
 516
 517 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 518    loop.  */
 519
 520 static inline struct loop *
 521 loop_outer (const struct loop *loop)
 522 {
 523   unsigned n = vec_safe_length (loop->superloops);
 524
 525   if (n == 0)
 526     return NULL;
 527
 528   return (*loop->superloops)[n - 1];
 529 }
 530
 531 /* Returns true if LOOP has at least one exit edge.  */
 532
 533 static inline bool
 534 loop_has_exit_edges (const struct loop *loop)
 535 {
 536   return loop->exits->next->e != NULL;
 537 }
 538
 539 /* Returns the list of loops in FN.  */
 540
 541 inline vec<loop_p, va_gc> *
 542 get_loops (struct function *fn)
 543 {
 544   struct loops *loops = loops_for_fn (fn);
 545   if (!loops)
 546     return NULL;
 547
 548   return loops->larray;
 549 }
 550
 551 /* Returns the number of loops in FN (including the removed
 552    ones and the fake loop that forms the root of the loop tree).  */
 553
 554 static inline unsigned
 555 number_of_loops (struct function *fn)
 556 {
 557   struct loops *loops = loops_for_fn (fn);
 558   if (!loops)
 559     return 0;
 560
 561   return vec_safe_length (loops->larray);
 562 }
 563
 564 /* Returns true if state of the loops satisfies all properties
 565    described by FLAGS.  */
 566
 567 static inline bool
 568 loops_state_satisfies_p (function *fn, unsigned flags)
 569 {
 570   return (loops_for_fn (fn)->state & flags) == flags;
 571 }
 572
 573 static inline bool
 574 loops_state_satisfies_p (unsigned flags)
 575 {
 576   return loops_state_satisfies_p (cfun, flags);
 577 }
 578
 579 /* Sets FLAGS to the loops state.  */
 580
 581 static inline void
 582 loops_state_set (function *fn, unsigned flags)
 583 {
 584   loops_for_fn (fn)->state |= flags;
 585 }
 586
 587 static inline void
 588 loops_state_set (unsigned flags)
 589 {
 590   loops_state_set (cfun, flags);
 591 }
 592
 593 /* Clears FLAGS from the loops state.  */
 594
 595 static inline void
 596 loops_state_clear (function *fn, unsigned flags)
 597 {
 598   loops_for_fn (fn)->state &= ~flags;
 599 }
 600
 601 static inline void
 602 loops_state_clear (unsigned flags)
 603 {
 604   if (!current_loops)
 605     return;
 606   loops_state_clear (cfun, flags);
 607 }
 608
 609 /* Check loop structure invariants, if internal consistency checks are
 610    enabled.  */
 611
 612 static inline void
 613 checking_verify_loop_structure (void)
 614 {
 615   /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
 616
 617      The loop optimizers should never make changes to the CFG which
 618      require loop fixups.  But the low level CFG manipulation code may
 619      set the flag conservatively.
 620
 621      Go ahead and clear the flag here.  That avoids the assert inside
 622      VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
 623      structures VERIFY_LOOP_STRUCTURE will detect it.
 624
 625      This also avoid the compile time cost of excessive fixups.  */
 626   loops_state_clear (LOOPS_NEED_FIXUP);
 627   if (flag_checking)
 628     verify_loop_structure ();
 629 }
 630
 631 /* Loop iterators.  */
 632
 633 /* Flags for loop iteration.  */
 634
 635 enum li_flags
 636 {
 637   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 638   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 639                                    starting from innermost ones.  */
 640   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 641 };
 642
 643 /* The iterator for loops.  */
 644
 645 struct loop_iterator
 646 {
 647   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 648   ~loop_iterator ();
 649
 650   inline loop_p next ();
 651
 652   /* The function we are visiting.  */
 653   function *fn;
 654
 655   /* The list of loops to visit.  */
 656   vec<int> to_visit;
 657
 658   /* The index of the actual loop.  */
 659   unsigned idx;
 660 };
 661
 662 inline loop_p
 663 loop_iterator::next ()
 664 {
 665   int anum;
 666
 667   while (this->to_visit.iterate (this->idx, &anum))
 668     {
 669       this->idx++;
 670       loop_p loop = get_loop (fn, anum);
 671       if (loop)
 672         return loop;
 673     }
 674
 675   return NULL;
 676 }
 677
 678 inline
 679 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 680 {
 681   struct loop *aloop;
 682   unsigned i;
 683   int mn;
 684
 685   this->idx = 0;
 686   this->fn = fn;
 687   if (!loops_for_fn (fn))
 688     {
 689       this->to_visit.create (0);
 690       *loop = NULL;
 691       return;
 692     }
 693
 694   this->to_visit.create (number_of_loops (fn));
 695   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 696
 697   if (flags & LI_ONLY_INNERMOST)
 698     {
 699       for (i = 0; vec_safe_iterate (loops_for_fn (fn)->larray, i, &aloop); i++)
 700         if (aloop != NULL
 701             && aloop->inner == NULL
 702             && aloop->num >= mn)
 703           this->to_visit.quick_push (aloop->num);
 704     }
 705   else if (flags & LI_FROM_INNERMOST)
 706     {
 707       /* Push the loops to LI->TO_VISIT in postorder.  */
 708       for (aloop = loops_for_fn (fn)->tree_root;
 709            aloop->inner != NULL;
 710            aloop = aloop->inner)
 711         continue;
 712
 713       while (1)
 714         {
 715           if (aloop->num >= mn)
 716             this->to_visit.quick_push (aloop->num);
 717
 718           if (aloop->next)
 719             {
 720               for (aloop = aloop->next;
 721                    aloop->inner != NULL;
 722                    aloop = aloop->inner)
 723                 continue;
 724             }
 725           else if (!loop_outer (aloop))
 726             break;
 727           else
 728             aloop = loop_outer (aloop);
 729         }
 730     }
 731   else
 732     {
 733       /* Push the loops to LI->TO_VISIT in preorder.  */
 734       aloop = loops_for_fn (fn)->tree_root;
 735       while (1)
 736         {
 737           if (aloop->num >= mn)
 738             this->to_visit.quick_push (aloop->num);
 739
 740           if (aloop->inner != NULL)
 741             aloop = aloop->inner;
 742           else
 743             {
 744               while (aloop != NULL && aloop->next == NULL)
 745                 aloop = loop_outer (aloop);
 746               if (aloop == NULL)
 747                 break;
 748               aloop = aloop->next;
 749             }
 750         }
 751     }
 752
 753   *loop = this->next ();
 754 }
 755
 756 inline
 757 loop_iterator::~loop_iterator ()
 758 {
 759   this->to_visit.release ();
 760 }
 761
 762 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 763   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 764        (LOOP); \
 765        (LOOP) = li.next ())
 766
 767 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 768   for (loop_iterator li(fn, &(LOOP), FLAGS); \
 769        (LOOP); \
 770        (LOOP) = li.next ())
 771
 772 /* The properties of the target.  */
 773 struct target_cfgloop {
 774   /* Number of available registers.  */
 775   unsigned x_target_avail_regs;
 776
 777   /* Number of available registers that are call-clobbered.  */
 778   unsigned x_target_clobbered_regs;
 779
 780   /* Number of registers reserved for temporary expressions.  */
 781   unsigned x_target_res_regs;
 782
 783   /* The cost for register when there still is some reserve, but we are
 784      approaching the number of available registers.  */
 785   unsigned x_target_reg_cost[2];
 786
 787   /* The cost for register when we need to spill.  */
 788   unsigned x_target_spill_cost[2];
 789 };
 790
 791 extern struct target_cfgloop default_target_cfgloop;
 792 #if SWITCHABLE_TARGET
 793 extern struct target_cfgloop *this_target_cfgloop;
 794 #else
 795 #define this_target_cfgloop (&default_target_cfgloop)
 796 #endif
 797
 798 #define target_avail_regs \
 799   (this_target_cfgloop->x_target_avail_regs)
 800 #define target_clobbered_regs \
 801   (this_target_cfgloop->x_target_clobbered_regs)
 802 #define target_res_regs \
 803   (this_target_cfgloop->x_target_res_regs)
 804 #define target_reg_cost \
 805   (this_target_cfgloop->x_target_reg_cost)
 806 #define target_spill_cost \
 807   (this_target_cfgloop->x_target_spill_cost)
 808
 809 /* Register pressure estimation for induction variable optimizations & loop
 810    invariant motion.  */
 811 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 812 extern void init_set_costs (void);
 813
 814 /* Loop optimizer initialization.  */
 815 extern void loop_optimizer_init (unsigned);
 816 extern void loop_optimizer_finalize (function *);
 817 inline void
 818 loop_optimizer_finalize ()
 819 {
 820   loop_optimizer_finalize (cfun);
 821 }
 822
 823 /* Optimization passes.  */
 824 enum
 825 {
 826   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 827   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 828 };
 829
 830 extern void doloop_optimize_loops (void);
 831 extern void move_loop_invariants (void);
 832 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 833
 834 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 835 static inline struct loop *
 836 loop_outermost (struct loop *loop)
 837 {
 838   unsigned n = vec_safe_length (loop->superloops);
 839
 840   if (n <= 1)
 841     return loop;
 842
 843   return (*loop->superloops)[1];
 844 }
 845
 846 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 847 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 848 extern HOST_WIDE_INT get_max_loop_iterations_int (const struct loop *);
 849 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (struct loop *);
 850 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 851 extern bool get_max_loop_iterations (const struct loop *loop, widest_int *nit);
 852 extern bool get_likely_max_loop_iterations (struct loop *loop, widest_int *nit);
 853 extern int bb_loop_depth (const_basic_block);
 854
 855 /* Converts VAL to widest_int.  */
 856
 857 static inline widest_int
 858 gcov_type_to_wide_int (gcov_type val)
 859 {
 860   HOST_WIDE_INT a[2];
 861
 862   a[0] = (unsigned HOST_WIDE_INT) val;
 863   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 864      the size of type.  */
 865   val >>= HOST_BITS_PER_WIDE_INT - 1;
 866   val >>= 1;
 867   a[1] = (unsigned HOST_WIDE_INT) val;
 868
 869   return widest_int::from_array (a, 2);
 870 }
 871 #endif /* GCC_CFGLOOP_H */