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1 /* Loop optimizations over tree-ssa.
2 Copyright (C) 2003-2020 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
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 3, or (at your option) any
9 later version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY 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 #include "config.h"
21 #include "system.h"
22 #include "coretypes.h"
23 #include "backend.h"
24 #include "tree.h"
25 #include "gimple.h"
26 #include "tree-pass.h"
27 #include "memmodel.h"
28 #include "tm_p.h"
29 #include "fold-const.h"
30 #include "gimple-iterator.h"
31 #include "tree-ssa-loop-ivopts.h"
32 #include "tree-ssa-loop-manip.h"
33 #include "tree-ssa-loop-niter.h"
34 #include "tree-ssa-loop.h"
35 #include "cfgloop.h"
36 #include "tree-inline.h"
37 #include "tree-scalar-evolution.h"
38 #include "tree-vectorizer.h"
39 #include "omp-general.h"
40 #include "diagnostic-core.h"
41 #include "stringpool.h"
42 #include "attribs.h"
43
44
45 /* A pass making sure loops are fixed up. */
46
47 namespace {
48
49 const pass_data pass_data_fix_loops =
50 {
51 GIMPLE_PASS, /* type */
52 "fix_loops", /* name */
53 OPTGROUP_LOOP, /* optinfo_flags */
54 TV_TREE_LOOP, /* tv_id */
55 PROP_cfg, /* properties_required */
56 0, /* properties_provided */
57 0, /* properties_destroyed */
58 0, /* todo_flags_start */
59 0, /* todo_flags_finish */
60 };
61
62 class pass_fix_loops : public gimple_opt_pass
63 {
64 public:
65 pass_fix_loops (gcc::context *ctxt)
66 : gimple_opt_pass (pass_data_fix_loops, ctxt)
67 {}
68
69 /* opt_pass methods: */
70 virtual bool gate (function *) { return flag_tree_loop_optimize; }
71
72 virtual unsigned int execute (function *fn);
73 }; // class pass_fix_loops
74
75 unsigned int
76 pass_fix_loops::execute (function *)
77 {
78 if (loops_state_satisfies_p (LOOPS_NEED_FIXUP))
79 {
80 calculate_dominance_info (CDI_DOMINATORS);
81 fix_loop_structure (NULL);
82 }
83 return 0;
84 }
85
86 } // anon namespace
87
88 gimple_opt_pass *
89 make_pass_fix_loops (gcc::context *ctxt)
90 {
91 return new pass_fix_loops (ctxt);
92 }
93
94
95 /* Gate for loop pass group. The group is controlled by -ftree-loop-optimize
96 but we also avoid running it when the IL doesn't contain any loop. */
97
98 static bool
99 gate_loop (function *fn)
100 {
101 if (!flag_tree_loop_optimize)
102 return false;
103
104 /* For -fdump-passes which runs before loop discovery print the
105 state of -ftree-loop-optimize. */
106 if (!loops_for_fn (fn))
107 return true;
108
109 return number_of_loops (fn) > 1;
110 }
111
112 /* The loop superpass. */
113
114 namespace {
115
116 const pass_data pass_data_tree_loop =
117 {
118 GIMPLE_PASS, /* type */
119 "loop", /* name */
120 OPTGROUP_LOOP, /* optinfo_flags */
121 TV_TREE_LOOP, /* tv_id */
122 PROP_cfg, /* properties_required */
123 0, /* properties_provided */
124 0, /* properties_destroyed */
125 0, /* todo_flags_start */
126 0, /* todo_flags_finish */
127 };
128
129 class pass_tree_loop : public gimple_opt_pass
130 {
131 public:
132 pass_tree_loop (gcc::context *ctxt)
133 : gimple_opt_pass (pass_data_tree_loop, ctxt)
134 {}
135
136 /* opt_pass methods: */
137 virtual bool gate (function *fn) { return gate_loop (fn); }
138
139 }; // class pass_tree_loop
140
141 } // anon namespace
142
143 gimple_opt_pass *
144 make_pass_tree_loop (gcc::context *ctxt)
145 {
146 return new pass_tree_loop (ctxt);
147 }
148
149 /* Gate for oacc kernels pass group. */
150
151 static bool
152 gate_oacc_kernels (function *fn)
153 {
154 if (!flag_openacc)
155 return false;
156
157 if (!lookup_attribute ("oacc kernels", DECL_ATTRIBUTES (fn->decl)))
158 return false;
159
160 class loop *loop;
161 FOR_EACH_LOOP (loop, 0)
162 if (loop->in_oacc_kernels_region)
163 return true;
164
165 return false;
166 }
167
168 /* The oacc kernels superpass. */
169
170 namespace {
171
172 const pass_data pass_data_oacc_kernels =
173 {
174 GIMPLE_PASS, /* type */
175 "oacc_kernels", /* name */
176 OPTGROUP_LOOP, /* optinfo_flags */
177 TV_TREE_LOOP, /* tv_id */
178 PROP_cfg, /* properties_required */
179 0, /* properties_provided */
180 0, /* properties_destroyed */
181 0, /* todo_flags_start */
182 0, /* todo_flags_finish */
183 };
184
185 class pass_oacc_kernels : public gimple_opt_pass
186 {
187 public:
188 pass_oacc_kernels (gcc::context *ctxt)
189 : gimple_opt_pass (pass_data_oacc_kernels, ctxt)
190 {}
191
192 /* opt_pass methods: */
193 virtual bool gate (function *fn) { return gate_oacc_kernels (fn); }
194
195 }; // class pass_oacc_kernels
196
197 } // anon namespace
198
199 gimple_opt_pass *
200 make_pass_oacc_kernels (gcc::context *ctxt)
201 {
202 return new pass_oacc_kernels (ctxt);
203 }
204
205 /* The ipa oacc superpass. */
206
207 namespace {
208
209 const pass_data pass_data_ipa_oacc =
210 {
211 SIMPLE_IPA_PASS, /* type */
212 "ipa_oacc", /* name */
213 OPTGROUP_LOOP, /* optinfo_flags */
214 TV_TREE_LOOP, /* tv_id */
215 PROP_cfg, /* properties_required */
216 0, /* properties_provided */
217 0, /* properties_destroyed */
218 0, /* todo_flags_start */
219 0, /* todo_flags_finish */
220 };
221
222 class pass_ipa_oacc : public simple_ipa_opt_pass
223 {
224 public:
225 pass_ipa_oacc (gcc::context *ctxt)
226 : simple_ipa_opt_pass (pass_data_ipa_oacc, ctxt)
227 {}
228
229 /* opt_pass methods: */
230 virtual bool gate (function *)
231 {
232 return (optimize
233 && flag_openacc
234 /* Don't bother doing anything if the program has errors. */
235 && !seen_error ());
236 }
237
238 }; // class pass_ipa_oacc
239
240 } // anon namespace
241
242 simple_ipa_opt_pass *
243 make_pass_ipa_oacc (gcc::context *ctxt)
244 {
245 return new pass_ipa_oacc (ctxt);
246 }
247
248 /* The ipa oacc kernels pass. */
249
250 namespace {
251
252 const pass_data pass_data_ipa_oacc_kernels =
253 {
254 SIMPLE_IPA_PASS, /* type */
255 "ipa_oacc_kernels", /* name */
256 OPTGROUP_LOOP, /* optinfo_flags */
257 TV_TREE_LOOP, /* tv_id */
258 PROP_cfg, /* properties_required */
259 0, /* properties_provided */
260 0, /* properties_destroyed */
261 0, /* todo_flags_start */
262 0, /* todo_flags_finish */
263 };
264
265 class pass_ipa_oacc_kernels : public simple_ipa_opt_pass
266 {
267 public:
268 pass_ipa_oacc_kernels (gcc::context *ctxt)
269 : simple_ipa_opt_pass (pass_data_ipa_oacc_kernels, ctxt)
270 {}
271
272 }; // class pass_ipa_oacc_kernels
273
274 } // anon namespace
275
276 simple_ipa_opt_pass *
277 make_pass_ipa_oacc_kernels (gcc::context *ctxt)
278 {
279 return new pass_ipa_oacc_kernels (ctxt);
280 }
281
282 /* The no-loop superpass. */
283
284 namespace {
285
286 const pass_data pass_data_tree_no_loop =
287 {
288 GIMPLE_PASS, /* type */
289 "no_loop", /* name */
290 OPTGROUP_NONE, /* optinfo_flags */
291 TV_TREE_NOLOOP, /* tv_id */
292 PROP_cfg, /* properties_required */
293 0, /* properties_provided */
294 0, /* properties_destroyed */
295 0, /* todo_flags_start */
296 0, /* todo_flags_finish */
297 };
298
299 class pass_tree_no_loop : public gimple_opt_pass
300 {
301 public:
302 pass_tree_no_loop (gcc::context *ctxt)
303 : gimple_opt_pass (pass_data_tree_no_loop, ctxt)
304 {}
305
306 /* opt_pass methods: */
307 virtual bool gate (function *fn) { return !gate_loop (fn); }
308
309 }; // class pass_tree_no_loop
310
311 } // anon namespace
312
313 gimple_opt_pass *
314 make_pass_tree_no_loop (gcc::context *ctxt)
315 {
316 return new pass_tree_no_loop (ctxt);
317 }
318
319
320 /* Loop optimizer initialization. */
321
322 namespace {
323
324 const pass_data pass_data_tree_loop_init =
325 {
326 GIMPLE_PASS, /* type */
327 "loopinit", /* name */
328 OPTGROUP_LOOP, /* optinfo_flags */
329 TV_NONE, /* tv_id */
330 PROP_cfg, /* properties_required */
331 0, /* properties_provided */
332 0, /* properties_destroyed */
333 TODO_update_address_taken, /* todo_flags_start */
334 0, /* todo_flags_finish */
335 };
336
337 class pass_tree_loop_init : public gimple_opt_pass
338 {
339 public:
340 pass_tree_loop_init (gcc::context *ctxt)
341 : gimple_opt_pass (pass_data_tree_loop_init, ctxt)
342 {}
343
344 /* opt_pass methods: */
345 virtual unsigned int execute (function *);
346
347 }; // class pass_tree_loop_init
348
349 unsigned int
350 pass_tree_loop_init::execute (function *fun ATTRIBUTE_UNUSED)
351 {
352 /* When processing a loop in the loop pipeline, we should be able to assert
353 that:
354 (loops_state_satisfies_p (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS
355 | LOOP_CLOSED_SSA)
356 && scev_initialized_p ())
357 */
358 loop_optimizer_init (LOOPS_NORMAL
359 | LOOPS_HAVE_RECORDED_EXITS);
360 rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
361 scev_initialize ();
362
363 return 0;
364 }
365
366 } // anon namespace
367
368 gimple_opt_pass *
369 make_pass_tree_loop_init (gcc::context *ctxt)
370 {
371 return new pass_tree_loop_init (ctxt);
372 }
373
374 /* Loop autovectorization. */
375
376 namespace {
377
378 const pass_data pass_data_vectorize =
379 {
380 GIMPLE_PASS, /* type */
381 "vect", /* name */
382 OPTGROUP_LOOP | OPTGROUP_VEC, /* optinfo_flags */
383 TV_TREE_VECTORIZATION, /* tv_id */
384 ( PROP_cfg | PROP_ssa ), /* properties_required */
385 0, /* properties_provided */
386 0, /* properties_destroyed */
387 0, /* todo_flags_start */
388 0, /* todo_flags_finish */
389 };
390
391 class pass_vectorize : public gimple_opt_pass
392 {
393 public:
394 pass_vectorize (gcc::context *ctxt)
395 : gimple_opt_pass (pass_data_vectorize, ctxt)
396 {}
397
398 /* opt_pass methods: */
399 virtual bool gate (function *fun)
400 {
401 return flag_tree_loop_vectorize || fun->has_force_vectorize_loops;
402 }
403
404 virtual unsigned int execute (function *);
405
406 }; // class pass_vectorize
407
408 unsigned int
409 pass_vectorize::execute (function *fun)
410 {
411 if (number_of_loops (fun) <= 1)
412 return 0;
413
414 return vectorize_loops ();
415 }
416
417 } // anon namespace
418
419 gimple_opt_pass *
420 make_pass_vectorize (gcc::context *ctxt)
421 {
422 return new pass_vectorize (ctxt);
423 }
424
425 /* Propagation of constants using scev. */
426
427 namespace {
428
429 const pass_data pass_data_scev_cprop =
430 {
431 GIMPLE_PASS, /* type */
432 "sccp", /* name */
433 OPTGROUP_LOOP, /* optinfo_flags */
434 TV_SCEV_CONST, /* tv_id */
435 ( PROP_cfg | PROP_ssa ), /* properties_required */
436 0, /* properties_provided */
437 0, /* properties_destroyed */
438 0, /* todo_flags_start */
439 0, /* todo_flags_finish */
440 };
441
442 class pass_scev_cprop : public gimple_opt_pass
443 {
444 public:
445 pass_scev_cprop (gcc::context *ctxt)
446 : gimple_opt_pass (pass_data_scev_cprop, ctxt)
447 {}
448
449 /* opt_pass methods: */
450 virtual bool gate (function *) { return flag_tree_scev_cprop; }
451 virtual unsigned int execute (function *);
452
453 }; // class pass_scev_cprop
454
455 unsigned
456 pass_scev_cprop::execute (function *)
457 {
458 class loop *loop;
459 bool any = false;
460
461 /* Perform final value replacement in loops, in case the replacement
462 expressions are cheap. */
463 FOR_EACH_LOOP (loop, LI_FROM_INNERMOST)
464 any |= final_value_replacement_loop (loop);
465
466 return any ? TODO_cleanup_cfg | TODO_update_ssa_only_virtuals : 0;
467 }
468
469 } // anon namespace
470
471 gimple_opt_pass *
472 make_pass_scev_cprop (gcc::context *ctxt)
473 {
474 return new pass_scev_cprop (ctxt);
475 }
476
477 /* Induction variable optimizations. */
478
479 namespace {
480
481 const pass_data pass_data_iv_optimize =
482 {
483 GIMPLE_PASS, /* type */
484 "ivopts", /* name */
485 OPTGROUP_LOOP, /* optinfo_flags */
486 TV_TREE_LOOP_IVOPTS, /* tv_id */
487 ( PROP_cfg | PROP_ssa ), /* properties_required */
488 0, /* properties_provided */
489 0, /* properties_destroyed */
490 0, /* todo_flags_start */
491 TODO_update_ssa, /* todo_flags_finish */
492 };
493
494 class pass_iv_optimize : public gimple_opt_pass
495 {
496 public:
497 pass_iv_optimize (gcc::context *ctxt)
498 : gimple_opt_pass (pass_data_iv_optimize, ctxt)
499 {}
500
501 /* opt_pass methods: */
502 virtual bool gate (function *) { return flag_ivopts != 0; }
503 virtual unsigned int execute (function *);
504
505 }; // class pass_iv_optimize
506
507 unsigned int
508 pass_iv_optimize::execute (function *fun)
509 {
510 if (number_of_loops (fun) <= 1)
511 return 0;
512
513 tree_ssa_iv_optimize ();
514 return 0;
515 }
516
517 } // anon namespace
518
519 gimple_opt_pass *
520 make_pass_iv_optimize (gcc::context *ctxt)
521 {
522 return new pass_iv_optimize (ctxt);
523 }
524
525 /* Loop optimizer finalization. */
526
527 static unsigned int
528 tree_ssa_loop_done (void)
529 {
530 free_numbers_of_iterations_estimates (cfun);
531 scev_finalize ();
532 loop_optimizer_finalize ();
533 return 0;
534 }
535
536 namespace {
537
538 const pass_data pass_data_tree_loop_done =
539 {
540 GIMPLE_PASS, /* type */
541 "loopdone", /* name */
542 OPTGROUP_LOOP, /* optinfo_flags */
543 TV_NONE, /* tv_id */
544 PROP_cfg, /* properties_required */
545 0, /* properties_provided */
546 0, /* properties_destroyed */
547 0, /* todo_flags_start */
548 TODO_cleanup_cfg, /* todo_flags_finish */
549 };
550
551 class pass_tree_loop_done : public gimple_opt_pass
552 {
553 public:
554 pass_tree_loop_done (gcc::context *ctxt)
555 : gimple_opt_pass (pass_data_tree_loop_done, ctxt)
556 {}
557
558 /* opt_pass methods: */
559 virtual unsigned int execute (function *) { return tree_ssa_loop_done (); }
560
561 }; // class pass_tree_loop_done
562
563 } // anon namespace
564
565 gimple_opt_pass *
566 make_pass_tree_loop_done (gcc::context *ctxt)
567 {
568 return new pass_tree_loop_done (ctxt);
569 }
570
571 /* Calls CBCK for each index in memory reference ADDR_P. There are two
572 kinds situations handled; in each of these cases, the memory reference
573 and DATA are passed to the callback:
574
575 Access to an array: ARRAY_{RANGE_}REF (base, index). In this case we also
576 pass the pointer to the index to the callback.
577
578 Pointer dereference: INDIRECT_REF (addr). In this case we also pass the
579 pointer to addr to the callback.
580
581 If the callback returns false, the whole search stops and false is returned.
582 Otherwise the function returns true after traversing through the whole
583 reference *ADDR_P. */
584
585 bool
586 for_each_index (tree *addr_p, bool (*cbck) (tree, tree *, void *), void *data)
587 {
588 tree *nxt, *idx;
589
590 for (; ; addr_p = nxt)
591 {
592 switch (TREE_CODE (*addr_p))
593 {
594 case SSA_NAME:
595 return cbck (*addr_p, addr_p, data);
596
597 case MEM_REF:
598 nxt = &TREE_OPERAND (*addr_p, 0);
599 return cbck (*addr_p, nxt, data);
600
601 case BIT_FIELD_REF:
602 case VIEW_CONVERT_EXPR:
603 case REALPART_EXPR:
604 case IMAGPART_EXPR:
605 nxt = &TREE_OPERAND (*addr_p, 0);
606 break;
607
608 case COMPONENT_REF:
609 /* If the component has varying offset, it behaves like index
610 as well. */
611 idx = &TREE_OPERAND (*addr_p, 2);
612 if (*idx
613 && !cbck (*addr_p, idx, data))
614 return false;
615
616 nxt = &TREE_OPERAND (*addr_p, 0);
617 break;
618
619 case ARRAY_REF:
620 case ARRAY_RANGE_REF:
621 nxt = &TREE_OPERAND (*addr_p, 0);
622 if (!cbck (*addr_p, &TREE_OPERAND (*addr_p, 1), data))
623 return false;
624 break;
625
626 case CONSTRUCTOR:
627 return true;
628
629 case ADDR_EXPR:
630 gcc_assert (is_gimple_min_invariant (*addr_p));
631 return true;
632
633 case TARGET_MEM_REF:
634 idx = &TMR_BASE (*addr_p);
635 if (*idx
636 && !cbck (*addr_p, idx, data))
637 return false;
638 idx = &TMR_INDEX (*addr_p);
639 if (*idx
640 && !cbck (*addr_p, idx, data))
641 return false;
642 idx = &TMR_INDEX2 (*addr_p);
643 if (*idx
644 && !cbck (*addr_p, idx, data))
645 return false;
646 return true;
647
648 default:
649 if (DECL_P (*addr_p)
650 || CONSTANT_CLASS_P (*addr_p))
651 return true;
652 gcc_unreachable ();
653 }
654 }
655 }
656
657
658 /* The name and the length of the currently generated variable
659 for lsm. */
660 #define MAX_LSM_NAME_LENGTH 40
661 static char lsm_tmp_name[MAX_LSM_NAME_LENGTH + 1];
662 static int lsm_tmp_name_length;
663
664 /* Adds S to lsm_tmp_name. */
665
666 static void
667 lsm_tmp_name_add (const char *s)
668 {
669 int l = strlen (s) + lsm_tmp_name_length;
670 if (l > MAX_LSM_NAME_LENGTH)
671 return;
672
673 strcpy (lsm_tmp_name + lsm_tmp_name_length, s);
674 lsm_tmp_name_length = l;
675 }
676
677 /* Stores the name for temporary variable that replaces REF to
678 lsm_tmp_name. */
679
680 static void
681 gen_lsm_tmp_name (tree ref)
682 {
683 const char *name;
684
685 switch (TREE_CODE (ref))
686 {
687 case MEM_REF:
688 case TARGET_MEM_REF:
689 gen_lsm_tmp_name (TREE_OPERAND (ref, 0));
690 lsm_tmp_name_add ("_");
691 break;
692
693 case ADDR_EXPR:
694 gen_lsm_tmp_name (TREE_OPERAND (ref, 0));
695 break;
696
697 case BIT_FIELD_REF:
698 case VIEW_CONVERT_EXPR:
699 case ARRAY_RANGE_REF:
700 gen_lsm_tmp_name (TREE_OPERAND (ref, 0));
701 break;
702
703 case REALPART_EXPR:
704 gen_lsm_tmp_name (TREE_OPERAND (ref, 0));
705 lsm_tmp_name_add ("_RE");
706 break;
707
708 case IMAGPART_EXPR:
709 gen_lsm_tmp_name (TREE_OPERAND (ref, 0));
710 lsm_tmp_name_add ("_IM");
711 break;
712
713 case COMPONENT_REF:
714 gen_lsm_tmp_name (TREE_OPERAND (ref, 0));
715 lsm_tmp_name_add ("_");
716 name = get_name (TREE_OPERAND (ref, 1));
717 if (!name)
718 name = "F";
719 lsm_tmp_name_add (name);
720 break;
721
722 case ARRAY_REF:
723 gen_lsm_tmp_name (TREE_OPERAND (ref, 0));
724 lsm_tmp_name_add ("_I");
725 break;
726
727 case SSA_NAME:
728 case VAR_DECL:
729 case PARM_DECL:
730 case FUNCTION_DECL:
731 case LABEL_DECL:
732 name = get_name (ref);
733 if (!name)
734 name = "D";
735 lsm_tmp_name_add (name);
736 break;
737
738 case STRING_CST:
739 lsm_tmp_name_add ("S");
740 break;
741
742 case RESULT_DECL:
743 lsm_tmp_name_add ("R");
744 break;
745
746 case INTEGER_CST:
747 default:
748 /* Nothing. */
749 break;
750 }
751 }
752
753 /* Determines name for temporary variable that replaces REF.
754 The name is accumulated into the lsm_tmp_name variable.
755 N is added to the name of the temporary. */
756
757 char *
758 get_lsm_tmp_name (tree ref, unsigned n, const char *suffix)
759 {
760 char ns[2];
761
762 lsm_tmp_name_length = 0;
763 gen_lsm_tmp_name (ref);
764 lsm_tmp_name_add ("_lsm");
765 if (n < 10)
766 {
767 ns[0] = '0' + n;
768 ns[1] = 0;
769 lsm_tmp_name_add (ns);
770 }
771 if (suffix != NULL)
772 lsm_tmp_name_add (suffix);
773 return lsm_tmp_name;
774 }
775
776 /* Computes an estimated number of insns in LOOP, weighted by WEIGHTS. */
777
778 unsigned
779 tree_num_loop_insns (class loop *loop, eni_weights *weights)
780 {
781 basic_block *body = get_loop_body (loop);
782 gimple_stmt_iterator gsi;
783 unsigned size = 0, i;
784
785 for (i = 0; i < loop->num_nodes; i++)
786 for (gsi = gsi_start_bb (body[i]); !gsi_end_p (gsi); gsi_next (&gsi))
787 size += estimate_num_insns (gsi_stmt (gsi), weights);
788 free (body);
789
790 return size;
791 }
792
793
794