gcc/cfgloop.h

   1 /* Natural loop functions
   2    Copyright (C) 1987-2020 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 extern basic_block *get_loop_body_in_custom_order (const class loop *, void *,
 380                                int (*) (const void *, const void *, void *));
 381
 382 extern vec<edge> get_loop_exit_edges (const class loop *, basic_block * = NULL);
 383 extern edge single_exit (const class loop *);
 384 extern edge single_likely_exit (class loop *loop, vec<edge>);
 385 extern unsigned num_loop_branches (const class loop *);
 386
 387 extern edge loop_preheader_edge (const class loop *);
 388 extern edge loop_latch_edge (const class loop *);
 389
 390 extern void add_bb_to_loop (basic_block, class loop *);
 391 extern void remove_bb_from_loops (basic_block);
 392
 393 extern void cancel_loop_tree (class loop *);
 394 extern void delete_loop (class loop *);
 395
 396
 397 extern void verify_loop_structure (void);
 398
 399 /* Loop analysis.  */
 400 extern bool just_once_each_iteration_p (const class loop *, const_basic_block);
 401 gcov_type expected_loop_iterations_unbounded (const class loop *,
 402                                               bool *read_profile_p = NULL, bool by_profile_only = false);
 403 extern unsigned expected_loop_iterations (class loop *);
 404 extern rtx doloop_condition_get (rtx_insn *);
 405
 406 void mark_loop_for_removal (loop_p);
 407
 408 /* Induction variable analysis.  */
 409
 410 /* The description of induction variable.  The things are a bit complicated
 411    due to need to handle subregs and extends.  The value of the object described
 412    by it can be obtained as follows (all computations are done in extend_mode):
 413
 414    Value in i-th iteration is
 415      delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
 416
 417    If first_special is true, the value in the first iteration is
 418      delta + mult * base
 419
 420    If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
 421      subreg_{mode} (base + i * step)
 422
 423    The get_iv_value function can be used to obtain these expressions.
 424
 425    ??? Add a third mode field that would specify the mode in that inner
 426    computation is done, which would enable it to be different from the
 427    outer one?  */
 428
 429 class rtx_iv
 430 {
 431 public:
 432   /* Its base and step (mode of base and step is supposed to be extend_mode,
 433      see the description above).  */
 434   rtx base, step;
 435
 436   /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
 437      or IV_UNKNOWN_EXTEND).  */
 438   enum iv_extend_code extend;
 439
 440   /* Operations applied in the extended mode.  */
 441   rtx delta, mult;
 442
 443   /* The mode it is extended to.  */
 444   scalar_int_mode extend_mode;
 445
 446   /* The mode the variable iterates in.  */
 447   scalar_int_mode mode;
 448
 449   /* Whether the first iteration needs to be handled specially.  */
 450   unsigned first_special : 1;
 451 };
 452
 453 /* The description of an exit from the loop and of the number of iterations
 454    till we take the exit.  */
 455
 456 class GTY(()) niter_desc
 457 {
 458 public:
 459   /* The edge out of the loop.  */
 460   edge out_edge;
 461
 462   /* The other edge leading from the condition.  */
 463   edge in_edge;
 464
 465   /* True if we are able to say anything about number of iterations of the
 466      loop.  */
 467   bool simple_p;
 468
 469   /* True if the loop iterates the constant number of times.  */
 470   bool const_iter;
 471
 472   /* Number of iterations if constant.  */
 473   uint64_t niter;
 474
 475   /* Assumptions under that the rest of the information is valid.  */
 476   rtx assumptions;
 477
 478   /* Assumptions under that the loop ends before reaching the latch,
 479      even if value of niter_expr says otherwise.  */
 480   rtx noloop_assumptions;
 481
 482   /* Condition under that the loop is infinite.  */
 483   rtx infinite;
 484
 485   /* Whether the comparison is signed.  */
 486   bool signed_p;
 487
 488   /* The mode in that niter_expr should be computed.  */
 489   scalar_int_mode mode;
 490
 491   /* The number of iterations of the loop.  */
 492   rtx niter_expr;
 493 };
 494
 495 extern void iv_analysis_loop_init (class loop *);
 496 extern bool iv_analyze (rtx_insn *, scalar_int_mode, rtx, class rtx_iv *);
 497 extern bool iv_analyze_result (rtx_insn *, rtx, class rtx_iv *);
 498 extern bool iv_analyze_expr (rtx_insn *, scalar_int_mode, rtx,
 499                              class rtx_iv *);
 500 extern rtx get_iv_value (class rtx_iv *, rtx);
 501 extern bool biv_p (rtx_insn *, scalar_int_mode, rtx);
 502 extern void find_simple_exit (class loop *, class niter_desc *);
 503 extern void iv_analysis_done (void);
 504
 505 extern class niter_desc *get_simple_loop_desc (class loop *loop);
 506 extern void free_simple_loop_desc (class loop *loop);
 507
 508 static inline class niter_desc *
 509 simple_loop_desc (class loop *loop)
 510 {
 511   return loop->simple_loop_desc;
 512 }
 513
 514 /* Accessors for the loop structures.  */
 515
 516 /* Returns the loop with index NUM from FNs loop tree.  */
 517
 518 static inline class loop *
 519 get_loop (struct function *fn, unsigned num)
 520 {
 521   return (*loops_for_fn (fn)->larray)[num];
 522 }
 523
 524 /* Returns the number of superloops of LOOP.  */
 525
 526 static inline unsigned
 527 loop_depth (const class loop *loop)
 528 {
 529   return vec_safe_length (loop->superloops);
 530 }
 531
 532 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
 533    loop.  */
 534
 535 static inline class loop *
 536 loop_outer (const class loop *loop)
 537 {
 538   unsigned n = vec_safe_length (loop->superloops);
 539
 540   if (n == 0)
 541     return NULL;
 542
 543   return (*loop->superloops)[n - 1];
 544 }
 545
 546 /* Returns true if LOOP has at least one exit edge.  */
 547
 548 static inline bool
 549 loop_has_exit_edges (const class loop *loop)
 550 {
 551   return loop->exits->next->e != NULL;
 552 }
 553
 554 /* Returns the list of loops in FN.  */
 555
 556 inline vec<loop_p, va_gc> *
 557 get_loops (struct function *fn)
 558 {
 559   struct loops *loops = loops_for_fn (fn);
 560   if (!loops)
 561     return NULL;
 562
 563   return loops->larray;
 564 }
 565
 566 /* Returns the number of loops in FN (including the removed
 567    ones and the fake loop that forms the root of the loop tree).  */
 568
 569 static inline unsigned
 570 number_of_loops (struct function *fn)
 571 {
 572   struct loops *loops = loops_for_fn (fn);
 573   if (!loops)
 574     return 0;
 575
 576   return vec_safe_length (loops->larray);
 577 }
 578
 579 /* Returns true if state of the loops satisfies all properties
 580    described by FLAGS.  */
 581
 582 static inline bool
 583 loops_state_satisfies_p (function *fn, unsigned flags)
 584 {
 585   return (loops_for_fn (fn)->state & flags) == flags;
 586 }
 587
 588 static inline bool
 589 loops_state_satisfies_p (unsigned flags)
 590 {
 591   return loops_state_satisfies_p (cfun, flags);
 592 }
 593
 594 /* Sets FLAGS to the loops state.  */
 595
 596 static inline void
 597 loops_state_set (function *fn, unsigned flags)
 598 {
 599   loops_for_fn (fn)->state |= flags;
 600 }
 601
 602 static inline void
 603 loops_state_set (unsigned flags)
 604 {
 605   loops_state_set (cfun, flags);
 606 }
 607
 608 /* Clears FLAGS from the loops state.  */
 609
 610 static inline void
 611 loops_state_clear (function *fn, unsigned flags)
 612 {
 613   loops_for_fn (fn)->state &= ~flags;
 614 }
 615
 616 static inline void
 617 loops_state_clear (unsigned flags)
 618 {
 619   if (!current_loops)
 620     return;
 621   loops_state_clear (cfun, flags);
 622 }
 623
 624 /* Check loop structure invariants, if internal consistency checks are
 625    enabled.  */
 626
 627 static inline void
 628 checking_verify_loop_structure (void)
 629 {
 630   /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
 631
 632      The loop optimizers should never make changes to the CFG which
 633      require loop fixups.  But the low level CFG manipulation code may
 634      set the flag conservatively.
 635
 636      Go ahead and clear the flag here.  That avoids the assert inside
 637      VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
 638      structures VERIFY_LOOP_STRUCTURE will detect it.
 639
 640      This also avoid the compile time cost of excessive fixups.  */
 641   loops_state_clear (LOOPS_NEED_FIXUP);
 642   if (flag_checking)
 643     verify_loop_structure ();
 644 }
 645
 646 /* Loop iterators.  */
 647
 648 /* Flags for loop iteration.  */
 649
 650 enum li_flags
 651 {
 652   LI_INCLUDE_ROOT = 1,          /* Include the fake root of the loop tree.  */
 653   LI_FROM_INNERMOST = 2,        /* Iterate over the loops in the reverse order,
 654                                    starting from innermost ones.  */
 655   LI_ONLY_INNERMOST = 4         /* Iterate only over innermost loops.  */
 656 };
 657
 658 /* The iterator for loops.  */
 659
 660 class loop_iterator
 661 {
 662 public:
 663   loop_iterator (function *fn, loop_p *loop, unsigned flags);
 664
 665   inline loop_p next ();
 666
 667   /* The function we are visiting.  */
 668   function *fn;
 669
 670   /* The list of loops to visit.  */
 671   auto_vec<int, 16> to_visit;
 672
 673   /* The index of the actual loop.  */
 674   unsigned idx;
 675 };
 676
 677 inline loop_p
 678 loop_iterator::next ()
 679 {
 680   int anum;
 681
 682   while (this->to_visit.iterate (this->idx, &anum))
 683     {
 684       this->idx++;
 685       loop_p loop = get_loop (fn, anum);
 686       if (loop)
 687         return loop;
 688     }
 689
 690   return NULL;
 691 }
 692
 693 inline
 694 loop_iterator::loop_iterator (function *fn, loop_p *loop, unsigned flags)
 695 {
 696   class loop *aloop;
 697   unsigned i;
 698   int mn;
 699
 700   this->idx = 0;
 701   this->fn = fn;
 702   if (!loops_for_fn (fn))
 703     {
 704       *loop = NULL;
 705       return;
 706     }
 707
 708   this->to_visit.reserve_exact (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 #define FOR_EACH_LOOP(LOOP, FLAGS) \
 771   for (loop_iterator li(cfun, &(LOOP), FLAGS); \
 772        (LOOP); \
 773        (LOOP) = li.next ())
 774
 775 #define FOR_EACH_LOOP_FN(FN, LOOP, FLAGS) \
 776   for (loop_iterator li(FN, &(LOOP), FLAGS); \
 777        (LOOP); \
 778        (LOOP) = li.next ())
 779
 780 /* The properties of the target.  */
 781 struct target_cfgloop {
 782   /* Number of available registers.  */
 783   unsigned x_target_avail_regs;
 784
 785   /* Number of available registers that are call-clobbered.  */
 786   unsigned x_target_clobbered_regs;
 787
 788   /* Number of registers reserved for temporary expressions.  */
 789   unsigned x_target_res_regs;
 790
 791   /* The cost for register when there still is some reserve, but we are
 792      approaching the number of available registers.  */
 793   unsigned x_target_reg_cost[2];
 794
 795   /* The cost for register when we need to spill.  */
 796   unsigned x_target_spill_cost[2];
 797 };
 798
 799 extern struct target_cfgloop default_target_cfgloop;
 800 #if SWITCHABLE_TARGET
 801 extern struct target_cfgloop *this_target_cfgloop;
 802 #else
 803 #define this_target_cfgloop (&default_target_cfgloop)
 804 #endif
 805
 806 #define target_avail_regs \
 807   (this_target_cfgloop->x_target_avail_regs)
 808 #define target_clobbered_regs \
 809   (this_target_cfgloop->x_target_clobbered_regs)
 810 #define target_res_regs \
 811   (this_target_cfgloop->x_target_res_regs)
 812 #define target_reg_cost \
 813   (this_target_cfgloop->x_target_reg_cost)
 814 #define target_spill_cost \
 815   (this_target_cfgloop->x_target_spill_cost)
 816
 817 /* Register pressure estimation for induction variable optimizations & loop
 818    invariant motion.  */
 819 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
 820 extern void init_set_costs (void);
 821
 822 /* Loop optimizer initialization.  */
 823 extern void loop_optimizer_init (unsigned);
 824 extern void loop_optimizer_finalize (function *);
 825 inline void
 826 loop_optimizer_finalize ()
 827 {
 828   loop_optimizer_finalize (cfun);
 829 }
 830
 831 /* Optimization passes.  */
 832 enum
 833 {
 834   UAP_UNROLL = 1,       /* Enables unrolling of loops if it seems profitable.  */
 835   UAP_UNROLL_ALL = 2    /* Enables unrolling of all loops.  */
 836 };
 837
 838 extern void doloop_optimize_loops (void);
 839 extern void move_loop_invariants (void);
 840 extern vec<basic_block> get_loop_hot_path (const class loop *loop);
 841
 842 /* Returns the outermost loop of the loop nest that contains LOOP.*/
 843 static inline class loop *
 844 loop_outermost (class loop *loop)
 845 {
 846   unsigned n = vec_safe_length (loop->superloops);
 847
 848   if (n <= 1)
 849     return loop;
 850
 851   return (*loop->superloops)[1];
 852 }
 853
 854 extern void record_niter_bound (class loop *, const widest_int &, bool, bool);
 855 extern HOST_WIDE_INT get_estimated_loop_iterations_int (class loop *);
 856 extern HOST_WIDE_INT get_max_loop_iterations_int (const class loop *);
 857 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (class loop *);
 858 extern bool get_estimated_loop_iterations (class loop *loop, widest_int *nit);
 859 extern bool get_max_loop_iterations (const class loop *loop, widest_int *nit);
 860 extern bool get_likely_max_loop_iterations (class loop *loop, widest_int *nit);
 861 extern int bb_loop_depth (const_basic_block);
 862
 863 /* Converts VAL to widest_int.  */
 864
 865 static inline widest_int
 866 gcov_type_to_wide_int (gcov_type val)
 867 {
 868   HOST_WIDE_INT a[2];
 869
 870   a[0] = (unsigned HOST_WIDE_INT) val;
 871   /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
 872      the size of type.  */
 873   val >>= HOST_BITS_PER_WIDE_INT - 1;
 874   val >>= 1;
 875   a[1] = (unsigned HOST_WIDE_INT) val;
 876
 877   return widest_int::from_array (a, 2);
 878 }
 879 #endif /* GCC_CFGLOOP_H */