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 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   /* If this loop was inlined the main clique of the callee which does
 231      not need remapping when copying the loop body.  */
 232   unsigned short owned_clique;
 233
 234   /* For SIMD loops, this is a unique identifier of the loop, referenced
 235      by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
 236      builtins.  */
 237   tree simduid;
 238
 239   /* In loop optimization, it's common to generate loops from the original
 240      loop.  This field records the index of the original loop which can be
 241      used to track the original loop from newly generated loops.  This can
 242      be done by calling function get_loop (cfun, orig_loop_num).  Note the
 243      original loop could be destroyed for various reasons thus no longer
 244      exists, as a result, function call to get_loop returns NULL pointer.
 245      In this case, this field should not be used and needs to be cleared
 246      whenever possible.  */
 247   int orig_loop_num;
 248
 249   /* Upper bound on number of iterations of a loop.  */
 250   struct nb_iter_bound *bounds;
 251
 252   /* Non-overflow control ivs of a loop.  */
 253   struct control_iv *control_ivs;
 254
 255   /* Head of the cyclic list of the exits of the loop.  */
 256   struct loop_exit *exits;
 257
 258   /* Number of iteration analysis data for RTL.  */
 259   struct niter_desc *simple_loop_desc;
 260
 261   /* For sanity checking during loop fixup we record here the former
 262      loop header for loops marked for removal.  Note that this prevents
 263      the basic-block from being collected but its index can still be
 264      reused.  */
 265   basic_block former_header;
 266 };
 267
 268 /* Set if the loop is known to be infinite.  */
 269 #define LOOP_C_INFINITE         (1 << 0)
 270 /* Set if the loop is known to be finite without any assumptions.  */
 271 #define LOOP_C_FINITE           (1 << 1)
 272
 273 /* Set C to the LOOP constraint.  */
 274 static inline void
 275 loop_constraint_set (struct loop *loop, unsigned c)
 276 {
 277   loop->constraints |= c;
 278 }
 279
 280 /* Clear C from the LOOP constraint.  */
 281 static inline void
 282 loop_constraint_clear (struct loop *loop, unsigned c)
 283 {
 284   loop->constraints &= ~c;
 285 }
 286
 287 /* Check if C is set in the LOOP constraint.  */
 288 static inline bool
 289 loop_constraint_set_p (struct loop *loop, unsigned c)
 290 {
 291   return (loop->constraints & c) == c;
 292 }
 293
 294 /* Flags for state of loop structure.  */
 295 enum
 296 {
 297   LOOPS_HAVE_PREHEADERS = 1,
 298   LOOPS_HAVE_SIMPLE_LATCHES = 2,
 299   LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
 300   LOOPS_HAVE_RECORDED_EXITS = 8,
 301   LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
 302   LOOP_CLOSED_SSA = 32,
 303   LOOPS_NEED_FIXUP = 64,
 304   LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
 305 };
 306
 307 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
 308                       | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
 309 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
 310
 311 /* Structure to hold CFG information about natural loops within a function.  */
 312 struct GTY (()) loops {
 313   /* State of loops.  */
 314   int state;
 315
 316   /* Array of the loops.  */
 317   vec<loop_p, va_gc> *larray;
 318
 319   /* Maps edges to the list of their descriptions as loop exits.  Edges
 320      whose sources or destinations have loop_father == NULL (which may
 321      happen during the cfg manipulations) should not appear in EXITS.  */
 322   hash_table<loop_exit_hasher> *GTY(()) exits;
 323
 324   /* Pointer to root of loop hierarchy tree.  */
 325   struct loop *tree_root;
 326 };
 327
 328 /* Loop recognition.  */
 329 bool bb_loop_header_p (basic_block);
 330 void init_loops_structure (struct function *, struct loops *, unsigned);
 331 extern struct loops *flow_loops_find (struct loops *);
 332 extern void disambiguate_loops_with_multiple_latches (void);
 333 extern void flow_loops_free (struct loops *);
 334 extern void flow_loops_dump (FILE *,
 335                              void (*)(const struct loop *, FILE *, int), int);
 336 extern void flow_loop_dump (const struct loop *, FILE *,
 337                             void (*)(const struct loop *, FILE *, int), int);
 338 struct loop *alloc_loop (void);
 339 extern void flow_loop_free (struct loop *);
 340 int flow_loop_nodes_find (basic_block, struct loop *);
 341 unsigned fix_loop_structure (bitmap changed_bbs);
 342 bool mark_irreducible_loops (void);
 343 void release_recorded_exits (function *);
 344 void record_loop_exits (void);
 345 void rescan_loop_exit (edge, bool, bool);
 346 void sort_sibling_loops (function *);
 347
 348 /* Loop data structure manipulation/querying.  */
 349 extern void flow_loop_tree_node_add (struct loop *, struct loop *,
 350                                      struct loop * = NULL);
 351 extern void flow_loop_tree_node_remove (struct loop *);
 352 extern bool flow_loop_nested_p  (const struct loop *, const struct loop *);
 353 extern bool flow_bb_inside_loop_p (const struct loop *, const_basic_block);
 354 extern struct loop * find_common_loop (struct loop *, struct loop *);
 355 struct loop *superloop_at_depth (struct loop *, unsigned);
 356 struct eni_weights;
 357 extern int num_loop_insns (const struct loop *);
 358 extern int average_num_loop_insns (const struct loop *);
 359 extern unsigned get_loop_level (const struct loop *);
 360 extern bool loop_exit_edge_p (const struct loop *, const_edge);
 361 extern bool loop_exits_to_bb_p (struct loop *, basic_block);
 362 extern bool loop_exits_from_bb_p (struct loop *, basic_block);
 363 extern void mark_loop_exit_edges (void);
 364 extern dump_user_location_t get_loop_location (struct loop *loop);
 365
 366 /* Loops & cfg manipulation.  */
 367 extern basic_block *get_loop_body (const struct loop *);
 368 extern unsigned get_loop_body_with_size (const struct loop *, basic_block *,
 369                                          unsigned);
 370 extern basic_block *get_loop_body_in_dom_order (const struct loop *);
 371 extern basic_block *get_loop_body_in_bfs_order (const struct loop *);
 372 extern basic_block *get_loop_body_in_custom_order (const struct loop *,
 373                                int (*) (const void *, const void *));
 374
 375 extern vec<edge> get_loop_exit_edges (const struct loop *);
 376 extern edge single_exit (const struct loop *);
 377 extern edge single_likely_exit (struct loop *loop);
 378 extern unsigned num_loop_branches (const struct loop *);
 379
 380 extern edge loop_preheader_edge (const struct loop *);
 381 extern edge loop_latch_edge (const struct loop *);
 382
 383 extern void add_bb_to_loop (basic_block, struct loop *);
 384 extern void remove_bb_from_loops (basic_block);
 385
 386 extern void cancel_loop_tree (struct loop *);
 387 extern void delete_loop (struct loop *);
 388
 389
 390 extern void verify_loop_structure (void);
 391
 392 /* Loop analysis.  */
 393 extern bool just_once_each_iteration_p (const struct loop *, const_basic_block);
 394 gcov_type expected_loop_iterations_unbounded (const struct loop *,
 395                                               bool *read_profile_p = NULL, bool by_profile_only = false);
 396 extern unsigned expected_loop_iterations (struct loop *);
 397 extern rtx doloop_condition_get (rtx_insn *);
 398
 399 void mark_loop_for_removal (loop_p);
 400
 401 /* Induction variable analysis.  */
 402
 403 /* The description of induction variable.  The things are a bit complicated
 404    due to need to handle subregs and extends.  The value of the object described
 405    by it can be obtained as follows (all computations are done in extend_mode):
 406
 407    Value in i-th iteration is
 408      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 409
 410    If first_special is true, the value in the first iteration is
 411      delta + mult * base
 412
 413    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 414      subreg_{mode} (base + i * step)
 415
 416    The get_iv_value function can be used to obtain these expressions.
 417
 418    ??? Add a third mode field that would specify the mode in that inner
 419    computation is done, which would enable it to be different from the
 420    outer one?  */
 421
 422 struct rtx_iv
 423 {
 424   /* Its base and step (mode of base and step is supposed to be extend_mode,
 425      see the description above).  */
 426   rtx base, step;
 427
 428   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 429      or IV_UNKNOWN_EXTEND).  */
 430   enum iv_extend_code extend;
 431
 432   /* Operations applied in the extended mode.  */
 433   rtx delta, mult;
 434
 435   /* The mode it is extended to.  */
 436   scalar_int_mode extend_mode;
 437
 438   /* The mode the variable iterates in.  */
 439   scalar_int_mode mode;
 440
 441   /* Whether the first iteration needs to be handled specially.  */
 442   unsigned first_special : 1;
 443 };
 444
 445 /* The description of an exit from the loop and of the number of iterations
 446    till we take the exit.  */
 447
 448 struct GTY(()) niter_desc
 449 {
 450   /* The edge out of the loop.  */
 451   edge out_edge;
 452
 453   /* The other edge leading from the condition.  */
 454   edge in_edge;
 455
 456   /* True if we are able to say anything about number of iterations of the
 457      loop.  */
 458   bool simple_p;
 459
 460   /* True if the loop iterates the constant number of times.  */
 461   bool const_iter;
 462
 463   /* Number of iterations if constant.  */
 464   uint64_t niter;
 465
 466   /* Assumptions under that the rest of the information is valid.  */
 467   rtx assumptions;
 468
 469   /* Assumptions under that the loop ends before reaching the latch,
 470      even if value of niter_expr says otherwise.  */
 471   rtx noloop_assumptions;
 472
 473   /* Condition under that the loop is infinite.  */
 474   rtx infinite;
 475
 476   /* Whether the comparison is signed.  */
 477   bool signed_p;
 478
 479   /* The mode in that niter_expr should be computed.  */
 480   scalar_int_mode mode;
 481
 482   /* The number of iterations of the loop.  */
 483   rtx niter_expr;
 484 };
 485
 486 extern void iv_analysis_loop_init (struct loop *);
 487 extern bool iv_analyze (rtx_insn *, scalar_int_mode, rtx, struct rtx_iv *);
 488 extern bool iv_analyze_result (rtx_insn *, rtx, struct rtx_iv *);
 489 extern bool iv_analyze_expr (rtx_insn *, scalar_int_mode, rtx,
 490                              struct rtx_iv *);
 491 extern rtx get_iv_value (struct rtx_iv *, rtx);
 492 extern bool biv_p (rtx_insn *, scalar_int_mode, rtx);
 493 extern void find_simple_exit (struct loop *, struct niter_desc *);
 494 extern void iv_analysis_done (void);
 495
 496 extern struct niter_desc *get_simple_loop_desc (struct loop *loop);
 497 extern void free_simple_loop_desc (struct loop *loop);
 498
 499 static inline struct niter_desc *
 500 simple_loop_desc (struct loop *loop)
 501 {
 502   return loop->simple_loop_desc;
 503 }
 504
 505 /* Accessors for the loop structures.  */
 506
 507 /* Returns the loop with index NUM from FNs loop tree.  */
 508
 509 static inline struct loop *
 510 get_loop (struct function *fn, unsigned num)
 511 {
 512   return (*loops_for_fn (fn)->larray)[num];
 513 }
 514
 515 /* Returns the number of superloops of LOOP.  */
 516
 517 static inline unsigned
 518 loop_depth (const struct loop *loop)
 519 {
 520   return vec_safe_length (loop->superloops);
 521 }
 522
 523 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 524    loop.  */
 525
 526 static inline struct loop *
 527 loop_outer (const struct loop *loop)
 528 {
 529   unsigned n = vec_safe_length (loop->superloops);
 530
 531   if (n == 0)
 532     return NULL;
 533
 534   return (*loop->superloops)[n - 1];
 535 }
 536
 537 /* Returns true if LOOP has at least one exit edge.  */
 538
 539 static inline bool
 540 loop_has_exit_edges (const struct loop *loop)
 541 {
 542   return loop->exits->next->e != NULL;
 543 }
 544
 545 /* Returns the list of loops in FN.  */
 546
 547 inline vec<loop_p, va_gc> *
 548 get_loops (struct function *fn)
 549 {
 550   struct loops *loops = loops_for_fn (fn);
 551   if (!loops)
 552     return NULL;
 553
 554   return loops->larray;
 555 }
 556
 557 /* Returns the number of loops in FN (including the removed
 558    ones and the fake loop that forms the root of the loop tree).  */
 559
 560 static inline unsigned
 561 number_of_loops (struct function *fn)
 562 {
 563   struct loops *loops = loops_for_fn (fn);
 564   if (!loops)
 565     return 0;
 566
 567   return vec_safe_length (loops->larray);
 568 }
 569
 570 /* Returns true if state of the loops satisfies all properties
 571    described by FLAGS.  */
 572
 573 static inline bool
 574 loops_state_satisfies_p (function *fn, unsigned flags)
 575 {
 576   return (loops_for_fn (fn)->state & flags) == flags;
 577 }
 578
 579 static inline bool
 580 loops_state_satisfies_p (unsigned flags)
 581 {
 582   return loops_state_satisfies_p (cfun, flags);
 583 }
 584
 585 /* Sets FLAGS to the loops state.  */
 586
 587 static inline void
 588 loops_state_set (function *fn, unsigned flags)
 589 {
 590   loops_for_fn (fn)->state |= flags;
 591 }
 592
 593 static inline void
 594 loops_state_set (unsigned flags)
 595 {
 596   loops_state_set (cfun, flags);
 597 }
 598
 599 /* Clears FLAGS from the loops state.  */
 600
 601 static inline void
 602 loops_state_clear (function *fn, unsigned flags)
 603 {
 604   loops_for_fn (fn)->state &= ~flags;
 605 }
 606
 607 static inline void
 608 loops_state_clear (unsigned flags)
 609 {
 610   if (!current_loops)
 611     return;
 612   loops_state_clear (cfun, flags);
 613 }
 614
 615 /* Check loop structure invariants, if internal consistency checks are
 616    enabled.  */
 617
 618 static inline void
 619 checking_verify_loop_structure (void)
 620 {
 621   /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
 622
 623      The loop optimizers should never make changes to the CFG which
 624      require loop fixups.  But the low level CFG manipulation code may
 625      set the flag conservatively.
 626
 627      Go ahead and clear the flag here.  That avoids the assert inside
 628      VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
 629      structures VERIFY_LOOP_STRUCTURE will detect it.
 630
 631      This also avoid the compile time cost of excessive fixups.  */
 632   loops_state_clear (LOOPS_NEED_FIXUP);
 633   if (flag_checking)
 634     verify_loop_structure ();
 635 }
 636
 637 /* Loop iterators.  */
 638
 639 /* Flags for loop iteration.  */
 640
 641 enum li_flags
 642 {
 643   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 644   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 645                                    starting from innermost ones.  */
 646   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 647 };
 648
 649 /* The iterator for loops.  */
 650
 651 struct loop_iterator
 652 {
 653   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 654   ~loop_iterator ();
 655
 656   inline loop_p next ();
 657
 658   /* The function we are visiting.  */
 659   function *fn;
 660
 661   /* The list of loops to visit.  */
 662   vec<int> to_visit;
 663
 664   /* The index of the actual loop.  */
 665   unsigned idx;
 666 };
 667
 668 inline loop_p
 669 loop_iterator::next ()
 670 {
 671   int anum;
 672
 673   while (this->to_visit.iterate (this->idx, &anum))
 674     {
 675       this->idx++;
 676       loop_p loop = get_loop (fn, anum);
 677       if (loop)
 678         return loop;
 679     }
 680
 681   return NULL;
 682 }
 683
 684 inline
 685 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 686 {
 687   struct loop *aloop;
 688   unsigned i;
 689   int mn;
 690
 691   this->idx = 0;
 692   this->fn = fn;
 693   if (!loops_for_fn (fn))
 694     {
 695       this->to_visit.create (0);
 696       *loop = NULL;
 697       return;
 698     }
 699
 700   this->to_visit.create (number_of_loops (fn));
 701   mn = (flags & LI_INCLUDE_ROOT) ? 0 : 1;
 702
 703   if (flags & LI_ONLY_INNERMOST)
 704     {
 705       for (i = 0; vec_safe_iterate (loops_for_fn (fn)->larray, i, &aloop); i++)
 706         if (aloop != NULL
 707             && aloop->inner == NULL
 708             && aloop->num >= mn)
 709           this->to_visit.quick_push (aloop->num);
 710     }
 711   else if (flags & LI_FROM_INNERMOST)
 712     {
 713       /* Push the loops to LI->TO_VISIT in postorder.  */
 714       for (aloop = loops_for_fn (fn)->tree_root;
 715            aloop->inner != NULL;
 716            aloop = aloop->inner)
 717         continue;
 718
 719       while (1)
 720         {
 721           if (aloop->num >= mn)
 722             this->to_visit.quick_push (aloop->num);
 723
 724           if (aloop->next)
 725             {
 726               for (aloop = aloop->next;
 727                    aloop->inner != NULL;
 728                    aloop = aloop->inner)
 729                 continue;
 730             }
 731           else if (!loop_outer (aloop))
 732             break;
 733           else
 734             aloop = loop_outer (aloop);
 735         }
 736     }
 737   else
 738     {
 739       /* Push the loops to LI->TO_VISIT in preorder.  */
 740       aloop = loops_for_fn (fn)->tree_root;
 741       while (1)
 742         {
 743           if (aloop->num >= mn)
 744             this->to_visit.quick_push (aloop->num);
 745
 746           if (aloop->inner != NULL)
 747             aloop = aloop->inner;
 748           else
 749             {
 750               while (aloop != NULL && aloop->next == NULL)
 751                 aloop = loop_outer (aloop);
 752               if (aloop == NULL)
 753                 break;
 754               aloop = aloop->next;
 755             }
 756         }
 757     }
 758
 759   *loop = this->next ();
 760 }
 761
 762 inline
 763 loop_iterator::~loop_iterator ()
 764 {
 765   this->to_visit.release ();
 766 }
 767
 768 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 769   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 770        (LOOP); \
 771        (LOOP) = li.next ())
 772
 773 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 774   for (loop_iterator li(FN, &(LOOP), FLAGS); \
 775        (LOOP); \
 776        (LOOP) = li.next ())
 777
 778 /* The properties of the target.  */
 779 struct target_cfgloop {
 780   /* Number of available registers.  */
 781   unsigned x_target_avail_regs;
 782
 783   /* Number of available registers that are call-clobbered.  */
 784   unsigned x_target_clobbered_regs;
 785
 786   /* Number of registers reserved for temporary expressions.  */
 787   unsigned x_target_res_regs;
 788
 789   /* The cost for register when there still is some reserve, but we are
 790      approaching the number of available registers.  */
 791   unsigned x_target_reg_cost[2];
 792
 793   /* The cost for register when we need to spill.  */
 794   unsigned x_target_spill_cost[2];
 795 };
 796
 797 extern struct target_cfgloop default_target_cfgloop;
 798 #if SWITCHABLE_TARGET
 799 extern struct target_cfgloop *this_target_cfgloop;
 800 #else
 801 #define this_target_cfgloop (&default_target_cfgloop)
 802 #endif
 803
 804 #define target_avail_regs \
 805   (this_target_cfgloop->x_target_avail_regs)
 806 #define target_clobbered_regs \
 807   (this_target_cfgloop->x_target_clobbered_regs)
 808 #define target_res_regs \
 809   (this_target_cfgloop->x_target_res_regs)
 810 #define target_reg_cost \
 811   (this_target_cfgloop->x_target_reg_cost)
 812 #define target_spill_cost \
 813   (this_target_cfgloop->x_target_spill_cost)
 814
 815 /* Register pressure estimation for induction variable optimizations & loop
 816    invariant motion.  */
 817 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 818 extern void init_set_costs (void);
 819
 820 /* Loop optimizer initialization.  */
 821 extern void loop_optimizer_init (unsigned);
 822 extern void loop_optimizer_finalize (function *);
 823 inline void
 824 loop_optimizer_finalize ()
 825 {
 826   loop_optimizer_finalize (cfun);
 827 }
 828
 829 /* Optimization passes.  */
 830 enum
 831 {
 832   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 833   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 834 };
 835
 836 extern void doloop_optimize_loops (void);
 837 extern void move_loop_invariants (void);
 838 extern vec<basic_block> get_loop_hot_path (const struct loop *loop);
 839
 840 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 841 static inline struct loop *
 842 loop_outermost (struct loop *loop)
 843 {
 844   unsigned n = vec_safe_length (loop->superloops);
 845
 846   if (n <= 1)
 847     return loop;
 848
 849   return (*loop->superloops)[1];
 850 }
 851
 852 extern void record_niter_bound (struct loop *, const widest_int &, bool, bool);
 853 extern HOST_WIDE_INT get_estimated_loop_iterations_int (struct loop *);
 854 extern HOST_WIDE_INT get_max_loop_iterations_int (const struct loop *);
 855 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (struct loop *);
 856 extern bool get_estimated_loop_iterations (struct loop *loop, widest_int *nit);
 857 extern bool get_max_loop_iterations (const struct loop *loop, widest_int *nit);
 858 extern bool get_likely_max_loop_iterations (struct loop *loop, widest_int *nit);
 859 extern int bb_loop_depth (const_basic_block);
 860
 861 /* Converts VAL to widest_int.  */
 862
 863 static inline widest_int
 864 gcov_type_to_wide_int (gcov_type val)
 865 {
 866   HOST_WIDE_INT a[2];
 867
 868   a[0] = (unsigned HOST_WIDE_INT) val;
 869   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 870      the size of type.  */
 871   val >>= HOST_BITS_PER_WIDE_INT - 1;
 872   val >>= 1;
 873   a[1] = (unsigned HOST_WIDE_INT) val;
 874
 875   return widest_int::from_array (a, 2);
 876 }
 877 #endif /* GCC_CFGLOOP_H */