1 /* Natural loop functions
2 Copyright (C) 1987-2023 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, after executing the statement BOUND + 1 times, we will
64 leave the loop; that is, all the statements after it are executed at most
65 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 void *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 /* True if the loop is known to be finite. This is a localized
230 flag_finite_loops or similar pragmas state. */
231 unsigned finite_p : 1;
232
233 /* The number of times to unroll the loop. 0 means no information given,
234 just do what we always do. A value of 1 means do not unroll the loop.
235 A value of USHRT_MAX means unroll with no specific unrolling factor.
236 Other values means unroll with the given unrolling factor. */
237 unsigned short unroll;
238
239 /* If this loop was inlined the main clique of the callee which does
240 not need remapping when copying the loop body. */
241 unsigned short owned_clique;
242
243 /* For SIMD loops, this is a unique identifier of the loop, referenced
244 by IFN_GOMP_SIMD_VF, IFN_GOMP_SIMD_LANE and IFN_GOMP_SIMD_LAST_LANE
245 builtins. */
246 tree simduid;
247
248 /* In loop optimization, it's common to generate loops from the original
249 loop. This field records the index of the original loop which can be
250 used to track the original loop from newly generated loops. This can
251 be done by calling function get_loop (cfun, orig_loop_num). Note the
252 original loop could be destroyed for various reasons thus no longer
253 exists, as a result, function call to get_loop returns NULL pointer.
254 In this case, this field should not be used and needs to be cleared
255 whenever possible. */
256 int orig_loop_num;
257
258 /* Upper bound on number of iterations of a loop. */
259 class nb_iter_bound *bounds;
260
261 /* Non-overflow control ivs of a loop. */
262 struct control_iv *control_ivs;
263
264 /* Head of the cyclic list of the exits of the loop. */
265 struct loop_exit *exits;
266
267 /* Number of iteration analysis data for RTL. */
268 class niter_desc *simple_loop_desc;
269
270 /* For sanity checking during loop fixup we record here the former
271 loop header for loops marked for removal. Note that this prevents
272 the basic-block from being collected but its index can still be
273 reused. */
274 basic_block former_header;
275 };
276
277 /* Set if the loop is known to be infinite. */
278 #define LOOP_C_INFINITE (1 << 0)
279 /* Set if the loop is known to be finite without any assumptions. */
280 #define LOOP_C_FINITE (1 << 1)
281
282 /* Set C to the LOOP constraint. */
283 inline void
284 loop_constraint_set (class loop *loop, unsigned c)
285 {
286 loop->constraints |= c;
287 }
288
289 /* Clear C from the LOOP constraint. */
290 inline void
291 loop_constraint_clear (class loop *loop, unsigned c)
292 {
293 loop->constraints &= ~c;
294 }
295
296 /* Check if C is set in the LOOP constraint. */
297 inline bool
298 loop_constraint_set_p (class loop *loop, unsigned c)
299 {
300 return (loop->constraints & c) == c;
301 }
302
303 /* Flags for state of loop structure. */
304 enum
305 {
306 LOOPS_HAVE_PREHEADERS = 1,
307 LOOPS_HAVE_SIMPLE_LATCHES = 2,
308 LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS = 4,
309 LOOPS_HAVE_RECORDED_EXITS = 8,
310 LOOPS_MAY_HAVE_MULTIPLE_LATCHES = 16,
311 LOOP_CLOSED_SSA = 32,
312 LOOPS_NEED_FIXUP = 64,
313 LOOPS_HAVE_FALLTHRU_PREHEADERS = 128
314 };
315
316 #define LOOPS_NORMAL (LOOPS_HAVE_PREHEADERS | LOOPS_HAVE_SIMPLE_LATCHES \
317 | LOOPS_HAVE_MARKED_IRREDUCIBLE_REGIONS)
318 #define AVOID_CFG_MODIFICATIONS (LOOPS_MAY_HAVE_MULTIPLE_LATCHES)
319
320 /* Structure to hold CFG information about natural loops within a function. */
321 struct GTY (()) loops {
322 /* State of loops. */
323 int state;
324
325 /* Array of the loops. */
326 vec<loop_p, va_gc> *larray;
327
328 /* Maps edges to the list of their descriptions as loop exits. Edges
329 whose sources or destinations have loop_father == NULL (which may
330 happen during the cfg manipulations) should not appear in EXITS. */
331 hash_table<loop_exit_hasher> *GTY(()) exits;
332
333 /* Pointer to root of loop hierarchy tree. */
334 class loop *tree_root;
335 };
336
337 /* Loop recognition. */
338 bool bb_loop_header_p (basic_block);
339 void init_loops_structure (struct function *, struct loops *, unsigned);
340 extern struct loops *flow_loops_find (struct loops *);
341 extern void disambiguate_loops_with_multiple_latches (void);
342 extern void flow_loops_free (struct loops *);
343 extern void flow_loops_dump (FILE *,
344 void (*)(const class loop *, FILE *, int), int);
345 extern void flow_loop_dump (const class loop *, FILE *,
346 void (*)(const class loop *, FILE *, int), int);
347 class loop *alloc_loop (void);
348 extern void flow_loop_free (class loop *);
349 int flow_loop_nodes_find (basic_block, class loop *);
350 unsigned fix_loop_structure (bitmap changed_bbs);
351 bool mark_irreducible_loops (void);
352 void release_recorded_exits (function *);
353 void record_loop_exits (void);
354 void rescan_loop_exit (edge, bool, bool);
355 void sort_sibling_loops (function *);
356
357 /* Loop data structure manipulation/querying. */
358 extern void flow_loop_tree_node_add (class loop *, class loop *,
359 class loop * = NULL);
360 extern void flow_loop_tree_node_remove (class loop *);
361 extern bool flow_loop_nested_p (const class loop *, const class loop *);
362 extern bool flow_bb_inside_loop_p (const class loop *, const_basic_block);
363 extern class loop * find_common_loop (class loop *, class loop *);
364 class loop *superloop_at_depth (class loop *, unsigned);
365 struct eni_weights;
366 extern int num_loop_insns (const class loop *);
367 extern int average_num_loop_insns (const class loop *);
368 extern unsigned get_loop_level (const class loop *);
369 extern bool loop_exit_edge_p (const class loop *, const_edge);
370 extern bool loop_exits_to_bb_p (class loop *, basic_block);
371 extern bool loop_exits_from_bb_p (class loop *, basic_block);
372 extern void mark_loop_exit_edges (void);
373 extern dump_user_location_t get_loop_location (class loop *loop);
374
375 /* Loops & cfg manipulation. */
376 extern basic_block *get_loop_body (const class loop *);
377 extern unsigned get_loop_body_with_size (const class loop *, basic_block *,
378 unsigned);
379 extern basic_block *get_loop_body_in_dom_order (const class loop *);
380 extern basic_block *get_loop_body_in_bfs_order (const class loop *);
381 extern basic_block *get_loop_body_in_custom_order (const class loop *,
382 int (*) (const void *, const void *));
383 extern basic_block *get_loop_body_in_custom_order (const class loop *, void *,
384 int (*) (const void *, const void *, void *));
385
386 extern auto_vec<edge> get_loop_exit_edges (const class loop *, basic_block * = NULL);
387 extern edge single_exit (const class loop *);
388 extern edge single_likely_exit (class loop *loop, const vec<edge> &);
389 extern unsigned num_loop_branches (const class loop *);
390
391 extern edge loop_preheader_edge (const class loop *);
392 extern edge loop_latch_edge (const class loop *);
393
394 extern void add_bb_to_loop (basic_block, class loop *);
395 extern void remove_bb_from_loops (basic_block);
396
397 extern void cancel_loop_tree (class loop *);
398 extern void delete_loop (class loop *);
399
400
401 extern void verify_loop_structure (void);
402
403 /* Loop analysis. */
404 extern bool just_once_each_iteration_p (const class loop *, const_basic_block);
405 gcov_type expected_loop_iterations_unbounded (const class loop *,
406 bool *read_profile_p = NULL, bool by_profile_only = false);
407 extern unsigned expected_loop_iterations (class loop *);
408 extern rtx doloop_condition_get (rtx_insn *);
409
410 void mark_loop_for_removal (loop_p);
411
412 /* Induction variable analysis. */
413
414 /* The description of induction variable. The things are a bit complicated
415 due to need to handle subregs and extends. The value of the object described
416 by it can be obtained as follows (all computations are done in extend_mode):
417
418 Value in i-th iteration is
419 delta + mult * extend_{extend_mode} (subreg_{mode} (base + i * step)).
420
421 If first_special is true, the value in the first iteration is
422 delta + mult * base
423
424 If extend = UNKNOWN, first_special must be false, delta 0, mult 1 and value is
425 subreg_{mode} (base + i * step)
426
427 The get_iv_value function can be used to obtain these expressions.
428
429 ??? Add a third mode field that would specify the mode in that inner
430 computation is done, which would enable it to be different from the
431 outer one? */
432
433 class rtx_iv
434 {
435 public:
436 /* Its base and step (mode of base and step is supposed to be extend_mode,
437 see the description above). */
438 rtx base, step;
439
440 /* The type of extend applied to it (IV_SIGN_EXTEND, IV_ZERO_EXTEND,
441 or IV_UNKNOWN_EXTEND). */
442 enum iv_extend_code extend;
443
444 /* Operations applied in the extended mode. */
445 rtx delta, mult;
446
447 /* The mode it is extended to. */
448 scalar_int_mode extend_mode;
449
450 /* The mode the variable iterates in. */
451 scalar_int_mode mode;
452
453 /* Whether the first iteration needs to be handled specially. */
454 unsigned first_special : 1;
455 };
456
457 /* The description of an exit from the loop and of the number of iterations
458 till we take the exit. */
459
460 class GTY(()) niter_desc
461 {
462 public:
463 /* The edge out of the loop. */
464 edge out_edge;
465
466 /* The other edge leading from the condition. */
467 edge in_edge;
468
469 /* True if we are able to say anything about number of iterations of the
470 loop. */
471 bool simple_p;
472
473 /* True if the loop iterates the constant number of times. */
474 bool const_iter;
475
476 /* Number of iterations if constant. */
477 uint64_t niter;
478
479 /* Assumptions under that the rest of the information is valid. */
480 rtx assumptions;
481
482 /* Assumptions under that the loop ends before reaching the latch,
483 even if value of niter_expr says otherwise. */
484 rtx noloop_assumptions;
485
486 /* Condition under that the loop is infinite. */
487 rtx infinite;
488
489 /* Whether the comparison is signed. */
490 bool signed_p;
491
492 /* The mode in that niter_expr should be computed. */
493 scalar_int_mode mode;
494
495 /* The number of iterations of the loop. */
496 rtx niter_expr;
497 };
498
499 extern void iv_analysis_loop_init (class loop *);
500 extern bool iv_analyze (rtx_insn *, scalar_int_mode, rtx, class rtx_iv *);
501 extern bool iv_analyze_result (rtx_insn *, rtx, class rtx_iv *);
502 extern bool iv_analyze_expr (rtx_insn *, scalar_int_mode, rtx,
503 class rtx_iv *);
504 extern rtx get_iv_value (class rtx_iv *, rtx);
505 extern bool biv_p (rtx_insn *, scalar_int_mode, rtx);
506 extern void iv_analysis_done (void);
507
508 extern class niter_desc *get_simple_loop_desc (class loop *loop);
509 extern void free_simple_loop_desc (class loop *loop);
510
511 inline class niter_desc *
512 simple_loop_desc (class loop *loop)
513 {
514 return loop->simple_loop_desc;
515 }
516
517 /* Accessors for the loop structures. */
518
519 /* Returns the loop with index NUM from FNs loop tree. */
520
521 inline class loop *
522 get_loop (struct function *fn, unsigned num)
523 {
524 return (*loops_for_fn (fn)->larray)[num];
525 }
526
527 /* Returns the number of superloops of LOOP. */
528
529 inline unsigned
530 loop_depth (const class loop *loop)
531 {
532 return vec_safe_length (loop->superloops);
533 }
534
535 /* Returns the immediate superloop of LOOP, or NULL if LOOP is the outermost
536 loop. */
537
538 inline class loop *
539 loop_outer (const class loop *loop)
540 {
541 unsigned n = vec_safe_length (loop->superloops);
542
543 if (n == 0)
544 return NULL;
545
546 return (*loop->superloops)[n - 1];
547 }
548
549 /* Returns true if LOOP has at least one exit edge. */
550
551 inline bool
552 loop_has_exit_edges (const class loop *loop)
553 {
554 return loop->exits->next->e != NULL;
555 }
556
557 /* Returns the list of loops in FN. */
558
559 inline vec<loop_p, va_gc> *
560 get_loops (struct function *fn)
561 {
562 struct loops *loops = loops_for_fn (fn);
563 if (!loops)
564 return NULL;
565
566 return loops->larray;
567 }
568
569 /* Returns the number of loops in FN (including the removed
570 ones and the fake loop that forms the root of the loop tree). */
571
572 inline unsigned
573 number_of_loops (struct function *fn)
574 {
575 struct loops *loops = loops_for_fn (fn);
576 if (!loops)
577 return 0;
578
579 return vec_safe_length (loops->larray);
580 }
581
582 /* Returns true if state of the loops satisfies all properties
583 described by FLAGS. */
584
585 inline bool
586 loops_state_satisfies_p (function *fn, unsigned flags)
587 {
588 return (loops_for_fn (fn)->state & flags) == flags;
589 }
590
591 inline bool
592 loops_state_satisfies_p (unsigned flags)
593 {
594 return loops_state_satisfies_p (cfun, flags);
595 }
596
597 /* Sets FLAGS to the loops state. */
598
599 inline void
600 loops_state_set (function *fn, unsigned flags)
601 {
602 loops_for_fn (fn)->state |= flags;
603 }
604
605 inline void
606 loops_state_set (unsigned flags)
607 {
608 loops_state_set (cfun, flags);
609 }
610
611 /* Clears FLAGS from the loops state. */
612
613 inline void
614 loops_state_clear (function *fn, unsigned flags)
615 {
616 loops_for_fn (fn)->state &= ~flags;
617 }
618
619 inline void
620 loops_state_clear (unsigned flags)
621 {
622 if (!current_loops)
623 return;
624 loops_state_clear (cfun, flags);
625 }
626
627 /* Check loop structure invariants, if internal consistency checks are
628 enabled. */
629
630 inline void
631 checking_verify_loop_structure (void)
632 {
633 /* VERIFY_LOOP_STRUCTURE essentially asserts that no loops need fixups.
634
635 The loop optimizers should never make changes to the CFG which
636 require loop fixups. But the low level CFG manipulation code may
637 set the flag conservatively.
638
639 Go ahead and clear the flag here. That avoids the assert inside
640 VERIFY_LOOP_STRUCTURE, and if there is an inconsistency in the loop
641 structures VERIFY_LOOP_STRUCTURE will detect it.
642
643 This also avoid the compile time cost of excessive fixups. */
644 loops_state_clear (LOOPS_NEED_FIXUP);
645 if (flag_checking)
646 verify_loop_structure ();
647 }
648
649 /* Loop iterators. */
650
651 /* Flags for loop iteration. */
652
653 enum li_flags
654 {
655 LI_INCLUDE_ROOT = 1, /* Include the fake root of the loop tree. */
656 LI_FROM_INNERMOST = 2, /* Iterate over the loops in the reverse order,
657 starting from innermost ones. */
658 LI_ONLY_INNERMOST = 4 /* Iterate only over innermost loops. */
659 };
660
661 /* Provide the functionality of std::as_const to support range-based for
662 to use const iterator. (We can't use std::as_const itself because it's
663 a C++17 feature.) */
664 template <typename T>
665 constexpr const T &
666 as_const (T &t)
667 {
668 return t;
669 }
670
671 /* A list for visiting loops, which contains the loop numbers instead of
672 the loop pointers. If the loop ROOT is offered (non-null), the visiting
673 will start from it, otherwise it would start from the tree_root of
674 loops_for_fn (FN) instead. The scope is restricted in function FN and
675 the visiting order is specified by FLAGS. */
676
677 class loops_list
678 {
679 public:
680 loops_list (function *fn, unsigned flags, class loop *root = nullptr);
681
682 template <typename T> class Iter
683 {
684 public:
685 Iter (const loops_list &l, unsigned idx) : list (l), curr_idx (idx)
686 {
687 fill_curr_loop ();
688 }
689
690 T operator* () const { return curr_loop; }
691
692 Iter &
693 operator++ ()
694 {
695 if (curr_idx < list.to_visit.length ())
696 {
697 /* Bump the index and fill a new one. */
698 curr_idx++;
699 fill_curr_loop ();
700 }
701 else
702 gcc_assert (!curr_loop);
703
704 return *this;
705 }
706
707 bool
708 operator!= (const Iter &rhs) const
709 {
710 return this->curr_idx != rhs.curr_idx;
711 }
712
713 private:
714 /* Fill the current loop starting from the current index. */
715 void fill_curr_loop ();
716
717 /* Reference to the loop list to visit. */
718 const loops_list &list;
719
720 /* The current index in the list to visit. */
721 unsigned curr_idx;
722
723 /* The loop implied by the current index. */
724 class loop *curr_loop;
725 };
726
727 using iterator = Iter<class loop *>;
728 using const_iterator = Iter<const class loop *>;
729
730 iterator
731 begin ()
732 {
733 return iterator (*this, 0);
734 }
735
736 iterator
737 end ()
738 {
739 return iterator (*this, to_visit.length ());
740 }
741
742 const_iterator
743 begin () const
744 {
745 return const_iterator (*this, 0);
746 }
747
748 const_iterator
749 end () const
750 {
751 return const_iterator (*this, to_visit.length ());
752 }
753
754 private:
755 /* Walk loop tree starting from ROOT as the visiting order specified
756 by FLAGS. */
757 void walk_loop_tree (class loop *root, unsigned flags);
758
759 /* The function we are visiting. */
760 function *fn;
761
762 /* The list of loops to visit. */
763 auto_vec<int, 16> to_visit;
764 };
765
766 /* Starting from current index CURR_IDX (inclusive), find one index
767 which stands for one valid loop and fill the found loop as CURR_LOOP,
768 if we can't find one, set CURR_LOOP as null. */
769
770 template <typename T>
771 inline void
772 loops_list::Iter<T>::fill_curr_loop ()
773 {
774 int anum;
775
776 while (this->list.to_visit.iterate (this->curr_idx, &anum))
777 {
778 class loop *loop = get_loop (this->list.fn, anum);
779 if (loop)
780 {
781 curr_loop = loop;
782 return;
783 }
784 this->curr_idx++;
785 }
786
787 curr_loop = nullptr;
788 }
789
790 /* Set up the loops list to visit according to the specified
791 function scope FN and iterating order FLAGS. If ROOT is
792 not null, the visiting would start from it, otherwise it
793 will start from tree_root of loops_for_fn (FN). */
794
795 inline loops_list::loops_list (function *fn, unsigned flags, class loop *root)
796 {
797 struct loops *loops = loops_for_fn (fn);
798 gcc_assert (!root || loops);
799
800 /* Check mutually exclusive flags should not co-exist. */
801 unsigned checked_flags = LI_ONLY_INNERMOST | LI_FROM_INNERMOST;
802 gcc_assert ((flags & checked_flags) != checked_flags);
803
804 this->fn = fn;
805 if (!loops)
806 return;
807
808 class loop *tree_root = root ? root : loops->tree_root;
809
810 this->to_visit.reserve_exact (number_of_loops (fn));
811
812 /* When root is tree_root of loops_for_fn (fn) and the visiting
813 order is LI_ONLY_INNERMOST, we would like to use linear
814 search here since it has a more stable bound than the
815 walk_loop_tree. */
816 if (flags & LI_ONLY_INNERMOST && tree_root == loops->tree_root)
817 {
818 gcc_assert (tree_root->num == 0);
819 if (tree_root->inner == NULL)
820 {
821 if (flags & LI_INCLUDE_ROOT)
822 this->to_visit.quick_push (0);
823
824 return;
825 }
826
827 class loop *aloop;
828 unsigned int i;
829 for (i = 1; vec_safe_iterate (loops->larray, i, &aloop); i++)
830 if (aloop != NULL && aloop->inner == NULL)
831 this->to_visit.quick_push (aloop->num);
832 }
833 else
834 walk_loop_tree (tree_root, flags);
835 }
836
837 /* The properties of the target. */
838 struct target_cfgloop {
839 /* Number of available registers. */
840 unsigned x_target_avail_regs;
841
842 /* Number of available registers that are call-clobbered. */
843 unsigned x_target_clobbered_regs;
844
845 /* Number of registers reserved for temporary expressions. */
846 unsigned x_target_res_regs;
847
848 /* The cost for register when there still is some reserve, but we are
849 approaching the number of available registers. */
850 unsigned x_target_reg_cost[2];
851
852 /* The cost for register when we need to spill. */
853 unsigned x_target_spill_cost[2];
854 };
855
856 extern struct target_cfgloop default_target_cfgloop;
857 #if SWITCHABLE_TARGET
858 extern struct target_cfgloop *this_target_cfgloop;
859 #else
860 #define this_target_cfgloop (&default_target_cfgloop)
861 #endif
862
863 #define target_avail_regs \
864 (this_target_cfgloop->x_target_avail_regs)
865 #define target_clobbered_regs \
866 (this_target_cfgloop->x_target_clobbered_regs)
867 #define target_res_regs \
868 (this_target_cfgloop->x_target_res_regs)
869 #define target_reg_cost \
870 (this_target_cfgloop->x_target_reg_cost)
871 #define target_spill_cost \
872 (this_target_cfgloop->x_target_spill_cost)
873
874 /* Register pressure estimation for induction variable optimizations & loop
875 invariant motion. */
876 extern unsigned estimate_reg_pressure_cost (unsigned, unsigned, bool, bool);
877 extern void init_set_costs (void);
878
879 /* Loop optimizer initialization. */
880 extern void loop_optimizer_init (unsigned);
881 extern void loop_optimizer_finalize (function *, bool = false);
882 inline void
883 loop_optimizer_finalize ()
884 {
885 loop_optimizer_finalize (cfun);
886 }
887
888 /* Optimization passes. */
889 enum
890 {
891 UAP_UNROLL = 1, /* Enables unrolling of loops if it seems profitable. */
892 UAP_UNROLL_ALL = 2 /* Enables unrolling of all loops. */
893 };
894
895 extern void doloop_optimize_loops (void);
896 extern void move_loop_invariants (void);
897 extern auto_vec<basic_block> get_loop_hot_path (const class loop *loop);
898
899 /* Returns the outermost loop of the loop nest that contains LOOP.*/
900 inline class loop *
901 loop_outermost (class loop *loop)
902 {
903 unsigned n = vec_safe_length (loop->superloops);
904
905 if (n <= 1)
906 return loop;
907
908 return (*loop->superloops)[1];
909 }
910
911 extern void record_niter_bound (class loop *, const widest_int &, bool, bool);
912 extern HOST_WIDE_INT get_estimated_loop_iterations_int (class loop *);
913 extern HOST_WIDE_INT get_max_loop_iterations_int (const class loop *);
914 extern HOST_WIDE_INT get_likely_max_loop_iterations_int (class loop *);
915 extern bool get_estimated_loop_iterations (class loop *loop, widest_int *nit);
916 extern bool get_max_loop_iterations (const class loop *loop, widest_int *nit);
917 extern bool get_likely_max_loop_iterations (class loop *loop, widest_int *nit);
918 extern int bb_loop_depth (const_basic_block);
919
920 /* Converts VAL to widest_int. */
921
922 inline widest_int
923 gcov_type_to_wide_int (gcov_type val)
924 {
925 HOST_WIDE_INT a[2];
926
927 a[0] = (unsigned HOST_WIDE_INT) val;
928 /* If HOST_BITS_PER_WIDE_INT == HOST_BITS_PER_WIDEST_INT, avoid shifting by
929 the size of type. */
930 val >>= HOST_BITS_PER_WIDE_INT - 1;
931 val >>= 1;
932 a[1] = (unsigned HOST_WIDE_INT) val;
933
934 return widest_int::from_array (a, 2);
935 }
936 #endif /* GCC_CFGLOOP_H */