gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987-2019 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 class GTY ((chain_next ("%h.next"))) nb_iter_bound {
  50 public:
  51   /* The statement STMT is executed at most ...  */
  52   gimple *stmt;
  53
  54   /* ... BOUND + 1 times (BOUND must be an unsigned constant).
  55      The + 1 is added for the following reasons:
  56
  57      a) 0 would otherwise be unused, while we would need to care more about
  58         overflows (as MAX + 1 is sometimes produced as the estimate on number
  59         of executions of STMT).
  60      b) it is consistent with the result of number_of_iterations_exit.  */
  61   widest_int bound;
  62
  63   /* True if the statement will cause the loop to be leaved the (at most)
  64      BOUND + 1-st time it is executed, that is, all the statements after it
  65      are executed at most BOUND times.  */
  66   bool is_exit;
  67
  68   /* The next bound in the list.  */
  69   class nb_iter_bound *next;
  70 };
  71
  72 /* Description of the loop exit.  */
  73
  74 struct GTY ((for_user)) loop_exit {
  75   /* The exit edge.  */
  76   edge e;
  77
  78   /* Previous and next exit in the list of the exits of the loop.  */
  79   struct loop_exit *prev;
  80   struct loop_exit *next;
  81
  82   /* Next element in the list of loops from that E exits.  */
  83   struct loop_exit *next_e;
  84 };
  85
  86 struct loop_exit_hasher : ggc_ptr_hash<loop_exit>
  87 {
  88   typedef edge compare_type;
  89
  90   static hashval_t hash (loop_exit *);
  91   static bool equal (loop_exit *, edge);
  92   static void remove (loop_exit *);
  93 };
  94
  95 typedef class loop *loop_p;
  96
  97 /* An integer estimation of the number of iterations.  Estimate_state
  98    describes what is the state of the estimation.  */
  99 enum loop_estimation
 100 {
 101   /* Estimate was not computed yet.  */
 102   EST_NOT_COMPUTED,
 103   /* Estimate is ready.  */
 104   EST_AVAILABLE,
 105   EST_LAST
 106 };
 107
 108 /* The structure describing non-overflow control induction variable for
 109    loop's exit edge.  */
 110 struct GTY ((chain_next ("%h.next"))) control_iv {
 111   tree base;
 112   tree step;
 113   struct control_iv *next;
 114 };
 115
 116 /* Structure to hold information for each natural loop.  */
 117 class GTY ((chain_next ("%h.next"))) loop {
 118 public:
 119   /* Index into loops array.  Note indices will never be reused after loop
 120      is destroyed.  */
 121   int num;
 122
 123   /* Number of loop insns.  */
 124   unsigned ninsns;
 125
 126   /* Basic block of loop header.  */
 127   basic_block header;
 128
 129   /* Basic block of loop latch.  */
 130   basic_block latch;
 131
 132   /* For loop unrolling/peeling decision.  */
 133   struct lpt_decision lpt_decision;
 134
 135   /* Average number of executed insns per iteration.  */
 136   unsigned av_ninsns;
 137
 138   /* Number of blocks contained within the loop.  */
 139   unsigned num_nodes;
 140
 141   /* Superloops of the loop, starting with the outermost loop.  */
 142   vec<loop_p, va_gc> *superloops;
 143
 144   /* The first inner (child) loop or NULL if innermost loop.  */
 145   class loop *inner;
 146
 147   /* Link to the next (sibling) loop.  */
 148   class loop *next;
 149
 150   /* Auxiliary info specific to a pass.  */
 151   PTR GTY ((skip (""))) aux;
 152
 153   /* The number of times the latch of the loop is executed.  This can be an
 154      INTEGER_CST, or a symbolic expression representing the number of
 155      iterations like "N - 1", or a COND_EXPR containing the runtime
 156      conditions under which the number of iterations is non zero.
 157
 158      Don't access this field directly: number_of_latch_executions
 159      computes and caches the computed information in this field.  */
 160   tree nb_iterations;
 161
 162   /* An integer guaranteed to be greater or equal to nb_iterations.  Only
 163      valid if any_upper_bound is true.  */
 164   widest_int nb_iterations_upper_bound;
 165
 166   widest_int nb_iterations_likely_upper_bound;
 167
 168   /* An integer giving an estimate on nb_iterations.  Unlike
 169      nb_iterations_upper_bound, there is no guarantee that it is at least
 170      nb_iterations.  */
 171   widest_int nb_iterations_estimate;
 172
 173   /* If > 0, an integer, where the user asserted that for any
 174      I in [ 0, nb_iterations ) and for any J in
 175      [ I, min ( I + safelen, nb_iterations ) ), the Ith and Jth iterations
 176      of the loop can be safely evaluated concurrently.  */
 177   int safelen;
 178
 179   /* Preferred vectorization factor for the loop if non-zero.  */
 180   int simdlen;
 181
 182   /* Constraints are generally set by consumers and affect certain
 183      semantics of niter analyzer APIs.  Currently the APIs affected are
 184      number_of_iterations_exit* functions and their callers.  One typical
 185      use case of constraints is to vectorize possibly infinite loop:
 186
 187        1) Compute niter->assumptions by calling niter analyzer API and
 188           record it as possible condition for loop versioning.
 189        2) Clear buffered result of niter/scev analyzer.
 190        3) Set constraint LOOP_C_FINITE assuming the loop is finite.
 191        4) Analyze data references.  Since data reference analysis depends
 192           on niter/scev analyzer, the point is that niter/scev analysis
 193           is done under circumstance of LOOP_C_FINITE constraint.
 194        5) Version the loop with niter->assumptions computed in step 1).
 195        6) Vectorize the versioned loop in which niter->assumptions is
 196           checked to be true.
 197        7) Update constraints in versioned loops so that niter analyzer
 198           in following passes can use it.
 199
 200      Note consumers are usually the loop optimizers and it is consumers'
 201      responsibility to set/clear constraints correctly.  Failing to do
 202      that might result in hard to track down bugs in niter/scev consumers.  */
 203   unsigned constraints;
 204
 205   /* An integer estimation of the number of iterations.  Estimate_state
 206      describes what is the state of the estimation.  */
 207   ENUM_BITFIELD(loop_estimation) estimate_state : 8;
 208
 209   unsigned any_upper_bound : 1;
 210   unsigned any_estimate : 1;
 211   unsigned any_likely_upper_bound : 1;
 212
 213   /* True if the loop can be parallel.  */
 214   unsigned can_be_parallel : 1;
 215
 216   /* True if -Waggressive-loop-optimizations warned about this loop
 217      already.  */
 218   unsigned warned_aggressive_loop_optimizations : 1;
 219
 220   /* True if this loop should never be vectorized.  */
 221   unsigned dont_vectorize : 1;
 222
 223   /* True if we should try harder to vectorize this loop.  */
 224   unsigned force_vectorize : 1;
 225
 226   /* True if the loop is part of an oacc kernels region.  */
 227   unsigned in_oacc_kernels_region : 1;
 228
 229   /* The number of times to unroll the loop.  0 means no information given,
 230      just do what we always do.  A value of 1 means do not unroll the loop.
 231      A value of USHRT_MAX means unroll with no specific unrolling factor.
 232      Other values means unroll with the given unrolling factor.  */
 233   unsigned short unroll;
 234
 235   /* If this loop was inlined the main clique of the callee which does
 236      not need remapping when copying the loop body.  */
 237   unsigned short owned_clique;
 238
 239   /* For SIMD loops, this is a unique identifier of the loop, referenced
 240      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 241      builtins.  */
 242   tree simduid;
 243
 244   /* In loop optimization, it's common to generate loops from the original
 245      loop.  This field records the index of the original loop which can be
 246      used to track the original loop from newly generated loops.  This can
 247      be done by calling function get_loop (cfun, orig_loop_num).  Note the
 248      original loop could be destroyed for various reasons thus no longer
 249      exists, as a result, function call to get_loop returns NULL pointer.
 250      In this case, this field should not be used and needs to be cleared
 251      whenever possible.  */
 252   int orig_loop_num;
 253
 254   /* Upper bound on number of iterations of a loop.  */
 255   class nb_iter_bound *bounds;
 256
 257   /* Non-overflow control ivs of a loop.  */
 258   struct control_iv *control_ivs;
 259
 260   /* Head of the cyclic list of the exits of the loop.  */
 261   struct loop_exit *exits;
 262
 263   /* Number of iteration analysis data for RTL.  */
 264   class niter_desc *simple_loop_desc;
 265
 266   /* For sanity checking during loop fixup we record here the former
 267      loop header for loops marked for removal.  Note that this prevents
 268      the basic-block from being collected but its index can still be
 269      reused.  */
 270   basic_block former_header;
 271 };
 272
 273 /* Set if the loop is known to be infinite.  */
 274 #define LOOP_C_INFINITE         (1 << 0)
 275 /* Set if the loop is known to be finite without any assumptions.  */
 276 #define LOOP_C_FINITE           (1 << 1)
 277
 278 /* Set C to the LOOP constraint.  */
 279 static inline void
 280 loop_constraint_set (class loop *loop, unsigned c)
 281 {
 282   loop->constraints |= c;
 283 }
 284
 285 /* Clear C from the LOOP constraint.  */
 286 static inline void
 287 loop_constraint_clear (class loop *loop, unsigned c)
 288 {
 289   loop->constraints &= ~c;
 290 }
 291
 292 /* Check if C is set in the LOOP constraint.  */
 293 static inline bool
 294 loop_constraint_set_p (class loop *loop, unsigned c)
 295 {
 296   return (loop->constraints & c) == c;
 297 }
 298
 299 /* Flags for state of loop structure.  */
 300 enum
 301 {
 302   LOOPS_HAVE_PREHEADERS = 1,
 303   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 304   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 305   LOOPS_HAVE_RECORDED_EXITS = 8,
 306   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 307   LOOP_CLOSED_SSA = 32,
 308   LOOPS_NEED_FIXUP = 64,
 309   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 310 };
 311
 312 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 313                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 314 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 315
 316 /* Structure to hold CFG information about natural loops within a function.  */
 317 struct GTY (()) loops {
 318   /* State of loops.  */
 319   int state;
 320
 321   /* Array of the loops.  */
 322   vec<loop_p, va_gc> *larray;
 323
 324   /* Maps edges to the list of their descriptions as loop exits.  Edges
 325      whose sources or destinations have loop_father == NULL (which may
 326      happen during the cfg manipulations) should not appear in EXITS.  */
 327   hash_table<loop_exit_hasher> *GTY(()) exits;
 328
 329   /* Pointer to root of loop hierarchy tree.  */
 330   class loop *tree_root;
 331 };
 332
 333 /* Loop recognition.  */
 334 bool bb_loop_header_p (basic_block);
 335 void init_loops_structure (struct function *, struct loops *, unsigned);
 336 extern struct loops *flow_loops_find (struct loops *);
 337 extern void disambiguate_loops_with_multiple_latches (void);
 338 extern void flow_loops_free (struct loops *);
 339 extern void flow_loops_dump (FILE *,
 340                              void (*)(const class loop *, FILE *, int), int);
 341 extern void flow_loop_dump (const class loop *, FILE *,
 342                             void (*)(const class loop *, FILE *, int), int);
 343 class loop *alloc_loop (void);
 344 extern void flow_loop_free (class loop *);
 345 int flow_loop_nodes_find (basic_block, class loop *);
 346 unsigned fix_loop_structure (bitmap changed_bbs);
 347 bool mark_irreducible_loops (void);
 348 void release_recorded_exits (function *);
 349 void record_loop_exits (void);
 350 void rescan_loop_exit (edge, bool, bool);
 351 void sort_sibling_loops (function *);
 352
 353 /* Loop data structure manipulation/querying.  */
 354 extern void flow_loop_tree_node_add (class loop *, class loop *,
 355                                      class loop * = NULL);
 356 extern void flow_loop_tree_node_remove (class loop *);
 357 extern bool flow_loop_nested_p  (const class loop *, const class loop *);
 358 extern bool flow_bb_inside_loop_p (const class loop *, const_basic_block);
 359 extern class loop * find_common_loop (class loop *, class loop *);
 360 class loop *superloop_at_depth (class loop *, unsigned);
 361 struct eni_weights;
 362 extern int num_loop_insns (const class loop *);
 363 extern int average_num_loop_insns (const class loop *);
 364 extern unsigned get_loop_level (const class loop *);
 365 extern bool loop_exit_edge_p (const class loop *, const_edge);
 366 extern bool loop_exits_to_bb_p (class loop *, basic_block);
 367 extern bool loop_exits_from_bb_p (class loop *, basic_block);
 368 extern void mark_loop_exit_edges (void);
 369 extern dump_user_location_t get_loop_location (class loop *loop);
 370
 371 /* Loops & cfg manipulation.  */
 372 extern basic_block *get_loop_body (const class loop *);
 373 extern unsigned get_loop_body_with_size (const class loop *, basic_block *,
 374                                          unsigned);
 375 extern basic_block *get_loop_body_in_dom_order (const class loop *);
 376 extern basic_block *get_loop_body_in_bfs_order (const class loop *);
 377 extern basic_block *get_loop_body_in_custom_order (const class loop *,
 378                                int (*) (const void *, const void *));
 379
 380 extern vec<edge> get_loop_exit_edges (const class loop *);
 381 extern edge single_exit (const class loop *);
 382 extern edge single_likely_exit (class loop *loop);
 383 extern unsigned num_loop_branches (const class loop *);
 384
 385 extern edge loop_preheader_edge (const class loop *);
 386 extern edge loop_latch_edge (const class loop *);
 387
 388 extern void add_bb_to_loop (basic_block, class loop *);
 389 extern void remove_bb_from_loops (basic_block);
 390
 391 extern void cancel_loop_tree (class loop *);
 392 extern void delete_loop (class loop *);
 393
 394
 395 extern void verify_loop_structure (void);
 396
 397 /* Loop analysis.  */
 398 extern bool just_once_each_iteration_p (const class loop *, const_basic_block);
 399 gcov_type expected_loop_iterations_unbounded (const class loop *,
 400                                               bool *read_profile_p = NULL, bool by_profile_only = false);
 401 extern unsigned expected_loop_iterations (class loop *);
 402 extern rtx doloop_condition_get (rtx_insn *);
 403
 404 void mark_loop_for_removal (loop_p);
 405
 406 /* Induction variable analysis.  */
 407
 408 /* The description of induction variable.  The things are a bit complicated
 409    due to need to handle subregs and extends.  The value of the object described
 410    by it can be obtained as follows (all computations are done in extend_mode):
 411
 412    Value in i-th iteration is
 413      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 414
 415    If first_special is true, the value in the first iteration is
 416      delta + mult * base
 417
 418    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 419      subreg_{mode} (base + i * step)
 420
 421    The get_iv_value function can be used to obtain these expressions.
 422
 423    ??? Add a third mode field that would specify the mode in that inner
 424    computation is done, which would enable it to be different from the
 425    outer one?  */
 426
 427 class rtx_iv
 428 {
 429 public:
 430   /* Its base and step (mode of base and step is supposed to be extend_mode,
 431      see the description above).  */
 432   rtx base, step;
 433
 434   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 435      or IV_UNKNOWN_EXTEND).  */
 436   enum iv_extend_code extend;
 437
 438   /* Operations applied in the extended mode.  */
 439   rtx delta, mult;
 440
 441   /* The mode it is extended to.  */
 442   scalar_int_mode extend_mode;
 443
 444   /* The mode the variable iterates in.  */
 445   scalar_int_mode mode;
 446
 447   /* Whether the first iteration needs to be handled specially.  */
 448   unsigned first_special : 1;
 449 };
 450
 451 /* The description of an exit from the loop and of the number of iterations
 452    till we take the exit.  */
 453
 454 class GTY(()) niter_desc
 455 {
 456 public:
 457   /* The edge out of the loop.  */
 458   edge out_edge;
 459
 460   /* The other edge leading from the condition.  */
 461   edge in_edge;
 462
 463   /* True if we are able to say anything about number of iterations of the
 464      loop.  */
 465   bool simple_p;
 466
 467   /* True if the loop iterates the constant number of times.  */
 468   bool const_iter;
 469
 470   /* Number of iterations if constant.  */
 471   uint64_t niter;
 472
 473   /* Assumptions under that the rest of the information is valid.  */
 474   rtx assumptions;
 475
 476   /* Assumptions under that the loop ends before reaching the latch,
 477      even if value of niter_expr says otherwise.  */
 478   rtx noloop_assumptions;
 479
 480   /* Condition under that the loop is infinite.  */
 481   rtx infinite;
 482
 483   /* Whether the comparison is signed.  */
 484   bool signed_p;
 485
 486   /* The mode in that niter_expr should be computed.  */
 487   scalar_int_mode mode;
 488
 489   /* The number of iterations of the loop.  */
 490   rtx niter_expr;
 491 };
 492
 493 extern void iv_analysis_loop_init (class loop *);
 494 extern bool iv_analyze (rtx_insn *, scalar_int_mode, rtx, class rtx_iv *);
 495 extern bool iv_analyze_result (rtx_insn *, rtx, class rtx_iv *);
 496 extern bool iv_analyze_expr (rtx_insn *, scalar_int_mode, rtx,
 497                              class rtx_iv *);
 498 extern rtx get_iv_value (class rtx_iv *, rtx);
 499 extern bool biv_p (rtx_insn *, scalar_int_mode, rtx);
 500 extern void find_simple_exit (class loop *, class niter_desc *);
 501 extern void iv_analysis_done (void);
 502
 503 extern class niter_desc *get_simple_loop_desc (class loop *loop);
 504 extern void free_simple_loop_desc (class loop *loop);
 505
 506 static inline class niter_desc *
 507 simple_loop_desc (class loop *loop)
 508 {
 509   return loop->simple_loop_desc;
 510 }
 511
 512 /* Accessors for the loop structures.  */
 513
 514 /* Returns the loop with index NUM from FNs loop tree.  */
 515
 516 static inline class loop *
 517 get_loop (struct function *fn, unsigned num)
 518 {
 519   return (*loops_for_fn (fn)->larray)[num];
 520 }
 521
 522 /* Returns the number of superloops of LOOP.  */
 523
 524 static inline unsigned
 525 loop_depth (const class loop *loop)
 526 {
 527   return vec_safe_length (loop->superloops);
 528 }
 529
 530 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 531    loop.  */
 532
 533 static inline class loop *
 534 loop_outer (const class loop *loop)
 535 {
 536   unsigned n = vec_safe_length (loop->superloops);
 537
 538   if (n == 0)
 539     return NULL;
 540
 541   return (*loop->superloops)[n - 1];
 542 }
 543
 544 /* Returns true if LOOP has at least one exit edge.  */
 545
 546 static inline bool
 547 loop_has_exit_edges (const class loop *loop)
 548 {
 549   return loop->exits->next->e != NULL;
 550 }
 551
 552 /* Returns the list of loops in FN.  */
 553
 554 inline vec<loop_p, va_gc> *
 555 get_loops (struct function *fn)
 556 {
 557   struct loops *loops = loops_for_fn (fn);
 558   if (!loops)
 559     return NULL;
 560
 561   return loops->larray;
 562 }
 563
 564 /* Returns the number of loops in FN (including the removed
 565    ones and the fake loop that forms the root of the loop tree).  */
 566
 567 static inline unsigned
 568 number_of_loops (struct function *fn)
 569 {
 570   struct loops *loops = loops_for_fn (fn);
 571   if (!loops)
 572     return 0;
 573
 574   return vec_safe_length (loops->larray);
 575 }
 576
 577 /* Returns true if state of the loops satisfies all properties
 578    described by FLAGS.  */
 579
 580 static inline bool
 581 loops_state_satisfies_p (function *fn, unsigned flags)
 582 {
 583   return (loops_for_fn (fn)->state & flags) == flags;
 584 }
 585
 586 static inline bool
 587 loops_state_satisfies_p (unsigned flags)
 588 {
 589   return loops_state_satisfies_p (cfun, flags);
 590 }
 591
 592 /* Sets FLAGS to the loops state.  */
 593
 594 static inline void
 595 loops_state_set (function *fn, unsigned flags)
 596 {
 597   loops_for_fn (fn)->state |= flags;
 598 }
 599
 600 static inline void
 601 loops_state_set (unsigned flags)
 602 {
 603   loops_state_set (cfun, flags);
 604 }
 605
 606 /* Clears FLAGS from the loops state.  */
 607
 608 static inline void
 609 loops_state_clear (function *fn, unsigned flags)
 610 {
 611   loops_for_fn (fn)->state &= ~flags;
 612 }
 613
 614 static inline void
 615 loops_state_clear (unsigned flags)
 616 {
 617   if (!current_loops)
 618     return;
 619   loops_state_clear (cfun, flags);
 620 }
 621
 622 /* Check loop structure invariants, if internal consistency checks are
 623    enabled.  */
 624
 625 static inline void
 626 checking_verify_loop_structure (void)
 627 {
 628   /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
 629
 630      The loop optimizers should never make changes to the CFG which
 631      require loop fixups.  But the low level CFG manipulation code may
 632      set the flag conservatively.
 633
 634      Go ahead and clear the flag here.  That avoids the assert inside
 635      VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
 636      structures VERIFY_LOOP_STRUCTURE will detect it.
 637
 638      This also avoid the compile time cost of excessive fixups.  */
 639   loops_state_clear (LOOPS_NEED_FIXUP);
 640   if (flag_checking)
 641     verify_loop_structure ();
 642 }
 643
 644 /* Loop iterators.  */
 645
 646 /* Flags for loop iteration.  */
 647
 648 enum li_flags
 649 {
 650   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 651   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 652                                    starting from innermost ones.  */
 653   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 654 };
 655
 656 /* The iterator for loops.  */
 657
 658 class loop_iterator
 659 {
 660 public:
 661   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 662   ~loop_iterator ();
 663
 664   inline loop_p next ();
 665
 666   /* The function we are visiting.  */
 667   function *fn;
 668
 669   /* The list of loops to visit.  */
 670   vec<int> to_visit;
 671
 672   /* The index of the actual loop.  */
 673   unsigned idx;
 674 };
 675
 676 inline loop_p
 677 loop_iterator::next ()
 678 {
 679   int anum;
 680
 681   while (this->to_visit.iterate (this->idx, &anum))
 682     {
 683       this->idx++;
 684       loop_p loop = get_loop (fn, anum);
 685       if (loop)
 686         return loop;
 687     }
 688
 689   return NULL;
 690 }
 691
 692 inline
 693 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 694 {
 695   class loop *aloop;
 696   unsigned i;
 697   int mn;
 698
 699   this->idx = 0;
 700   this->fn = fn;
 701   if (!loops_for_fn (fn))
 702     {
 703       this->to_visit.create (0);
 704       *loop = NULL;
 705       return;
 706     }
 707
 708   this->to_visit.create (number_of_loops (fn));
 709   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 710
 711   if (flags & LI_ONLY_INNERMOST)
 712     {
 713       for (i = 0; vec_safe_iterate (loops_for_fn (fn)->larray, i, &aloop); i++)
 714         if (aloop != NULL
 715             && aloop->inner == NULL
 716             && aloop->num >= mn)
 717           this->to_visit.quick_push (aloop->num);
 718     }
 719   else if (flags & LI_FROM_INNERMOST)
 720     {
 721       /* Push the loops to LI->TO_VISIT in postorder.  */
 722       for (aloop = loops_for_fn (fn)->tree_root;
 723            aloop->inner != NULL;
 724            aloop = aloop->inner)
 725         continue;
 726
 727       while (1)
 728         {
 729           if (aloop->num >= mn)
 730             this->to_visit.quick_push (aloop->num);
 731
 732           if (aloop->next)
 733             {
 734               for (aloop = aloop->next;
 735                    aloop->inner != NULL;
 736                    aloop = aloop->inner)
 737                 continue;
 738             }
 739           else if (!loop_outer (aloop))
 740             break;
 741           else
 742             aloop = loop_outer (aloop);
 743         }
 744     }
 745   else
 746     {
 747       /* Push the loops to LI->TO_VISIT in preorder.  */
 748       aloop = loops_for_fn (fn)->tree_root;
 749       while (1)
 750         {
 751           if (aloop->num >= mn)
 752             this->to_visit.quick_push (aloop->num);
 753
 754           if (aloop->inner != NULL)
 755             aloop = aloop->inner;
 756           else
 757             {
 758               while (aloop != NULL && aloop->next == NULL)
 759                 aloop = loop_outer (aloop);
 760               if (aloop == NULL)
 761                 break;
 762               aloop = aloop->next;
 763             }
 764         }
 765     }
 766
 767   *loop = this->next ();
 768 }
 769
 770 inline
 771 loop_iterator::~loop_iterator ()
 772 {
 773   this->to_visit.release ();
 774 }
 775
 776 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 777   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 778        (LOOP); \
 779        (LOOP) = li.next ())
 780
 781 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 782   for (loop_iterator li(FN, &(LOOP), FLAGS); \
 783        (LOOP); \
 784        (LOOP) = li.next ())
 785
 786 /* The properties of the target.  */
 787 struct target_cfgloop {
 788   /* Number of available registers.  */
 789   unsigned x_target_avail_regs;
 790
 791   /* Number of available registers that are call-clobbered.  */
 792   unsigned x_target_clobbered_regs;
 793
 794   /* Number of registers reserved for temporary expressions.  */
 795   unsigned x_target_res_regs;
 796
 797   /* The cost for register when there still is some reserve, but we are
 798      approaching the number of available registers.  */
 799   unsigned x_target_reg_cost[2];
 800
 801   /* The cost for register when we need to spill.  */
 802   unsigned x_target_spill_cost[2];
 803 };
 804
 805 extern struct target_cfgloop default_target_cfgloop;
 806 #if SWITCHABLE_TARGET
 807 extern struct target_cfgloop *this_target_cfgloop;
 808 #else
 809 #define this_target_cfgloop (&default_target_cfgloop)
 810 #endif
 811
 812 #define target_avail_regs \
 813   (this_target_cfgloop->x_target_avail_regs)
 814 #define target_clobbered_regs \
 815   (this_target_cfgloop->x_target_clobbered_regs)
 816 #define target_res_regs \
 817   (this_target_cfgloop->x_target_res_regs)
 818 #define target_reg_cost \
 819   (this_target_cfgloop->x_target_reg_cost)
 820 #define target_spill_cost \
 821   (this_target_cfgloop->x_target_spill_cost)
 822
 823 /* Register pressure estimation for induction variable optimizations & loop
 824    invariant motion.  */
 825 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 826 extern void init_set_costs (void);
 827
 828 /* Loop optimizer initialization.  */
 829 extern void loop_optimizer_init (unsigned);
 830 extern void loop_optimizer_finalize (function *);
 831 inline void
 832 loop_optimizer_finalize ()
 833 {
 834   loop_optimizer_finalize (cfun);
 835 }
 836
 837 /* Optimization passes.  */
 838 enum
 839 {
 840   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 841   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 842 };
 843
 844 extern void doloop_optimize_loops (void);
 845 extern void move_loop_invariants (void);
 846 extern vec<basic_block> get_loop_hot_path (const class loop *loop);
 847
 848 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 849 static inline class loop *
 850 loop_outermost (class loop *loop)
 851 {
 852   unsigned n = vec_safe_length (loop->superloops);
 853
 854   if (n <= 1)
 855     return loop;
 856
 857   return (*loop->superloops)[1];
 858 }
 859
 860 extern void record_niter_bound (class loop *, const widest_int &, bool, bool);
 861 extern HOST_WIDE_INT get_estimated_loop_iterations_int (class loop *);
 862 extern HOST_WIDE_INT get_max_loop_iterations_int (const class loop *);
 863 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (class loop *);
 864 extern bool get_estimated_loop_iterations (class loop *loop, widest_int *nit);
 865 extern bool get_max_loop_iterations (const class loop *loop, widest_int *nit);
 866 extern bool get_likely_max_loop_iterations (class loop *loop, widest_int *nit);
 867 extern int bb_loop_depth (const_basic_block);
 868
 869 /* Converts VAL to widest_int.  */
 870
 871 static inline widest_int
 872 gcov_type_to_wide_int (gcov_type val)
 873 {
 874   HOST_WIDE_INT a[2];
 875
 876   a[0] = (unsigned HOST_WIDE_INT) val;
 877   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 878      the size of type.  */
 879   val >>= HOST_BITS_PER_WIDE_INT - 1;
 880   val >>= 1;
 881   a[1] = (unsigned HOST_WIDE_INT) val;
 882
 883   return widest_int::from_array (a, 2);
 884 }
 885 #endif /* GCC_CFGLOOP_H */