pa.c (pa_som_asm_init_sections): Fix comment.
[official-gcc.git] / gcc / sched-ebb.c
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1 /* Instruction scheduling pass.
2 Copyright (C) 1992-2017 Free Software Foundation, Inc.
3 Contributed by Michael Tiemann (tiemann@cygnus.com) Enhanced by,
4 and currently maintained by, Jim Wilson (wilson@cygnus.com)
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
11 version.
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 for more details.
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 #include "config.h"
23 #include "system.h"
24 #include "coretypes.h"
25 #include "backend.h"
26 #include "target.h"
27 #include "rtl.h"
28 #include "cfghooks.h"
29 #include "df.h"
30 #include "profile.h"
31 #include "insn-attr.h"
32 #include "params.h"
33 #include "cfgrtl.h"
34 #include "cfgbuild.h"
35 #include "sched-int.h"
38 #ifdef INSN_SCHEDULING
40 /* The number of insns to be scheduled in total. */
41 static int rgn_n_insns;
43 /* The number of insns scheduled so far. */
44 static int sched_rgn_n_insns;
46 /* Set of blocks, that already have their dependencies calculated. */
47 static bitmap_head dont_calc_deps;
49 /* Last basic block in current ebb. */
50 static basic_block last_bb;
52 /* Implementations of the sched_info functions for region scheduling. */
53 static void init_ready_list (void);
54 static void begin_schedule_ready (rtx_insn *);
55 static int schedule_more_p (void);
56 static const char *ebb_print_insn (const rtx_insn *, int);
57 static int rank (rtx_insn *, rtx_insn *);
58 static int ebb_contributes_to_priority (rtx_insn *, rtx_insn *);
59 static basic_block earliest_block_with_similiar_load (basic_block, rtx);
60 static void add_deps_for_risky_insns (rtx_insn *, rtx_insn *);
61 static void debug_ebb_dependencies (rtx_insn *, rtx_insn *);
63 static void ebb_add_remove_insn (rtx_insn *, int);
64 static void ebb_add_block (basic_block, basic_block);
65 static basic_block advance_target_bb (basic_block, rtx_insn *);
66 static void ebb_fix_recovery_cfg (int, int, int);
68 /* Allocate memory and store the state of the frontend. Return the allocated
69 memory. */
70 static void *
71 save_ebb_state (void)
73 int *p = XNEW (int);
74 *p = sched_rgn_n_insns;
75 return p;
78 /* Restore the state of the frontend from P_, then free it. */
79 static void
80 restore_ebb_state (void *p_)
82 int *p = (int *)p_;
83 sched_rgn_n_insns = *p;
84 free (p_);
87 /* Return nonzero if there are more insns that should be scheduled. */
89 static int
90 schedule_more_p (void)
92 return sched_rgn_n_insns < rgn_n_insns;
95 /* Print dependency information about ebb between HEAD and TAIL. */
96 static void
97 debug_ebb_dependencies (rtx_insn *head, rtx_insn *tail)
99 fprintf (sched_dump,
100 ";; --------------- forward dependences: ------------ \n");
102 fprintf (sched_dump, "\n;; --- EBB Dependences --- from bb%d to bb%d \n",
103 BLOCK_NUM (head), BLOCK_NUM (tail));
105 debug_dependencies (head, tail);
108 /* Add all insns that are initially ready to the ready list READY. Called
109 once before scheduling a set of insns. */
111 static void
112 init_ready_list (void)
114 int n = 0;
115 rtx_insn *prev_head = current_sched_info->prev_head;
116 rtx_insn *next_tail = current_sched_info->next_tail;
117 rtx_insn *insn;
119 sched_rgn_n_insns = 0;
121 /* Print debugging information. */
122 if (sched_verbose >= 5)
123 debug_ebb_dependencies (NEXT_INSN (prev_head), PREV_INSN (next_tail));
125 /* Initialize ready list with all 'ready' insns in target block.
126 Count number of insns in the target block being scheduled. */
127 for (insn = NEXT_INSN (prev_head); insn != next_tail; insn = NEXT_INSN (insn))
129 try_ready (insn);
130 n++;
133 gcc_assert (n == rgn_n_insns);
136 /* INSN is being scheduled after LAST. Update counters. */
137 static void
138 begin_schedule_ready (rtx_insn *insn ATTRIBUTE_UNUSED)
140 sched_rgn_n_insns++;
143 /* INSN is being moved to its place in the schedule, after LAST. */
144 static void
145 begin_move_insn (rtx_insn *insn, rtx_insn *last)
147 if (BLOCK_FOR_INSN (insn) == last_bb
148 /* INSN is a jump in the last block, ... */
149 && control_flow_insn_p (insn)
150 /* that is going to be moved over some instructions. */
151 && last != PREV_INSN (insn))
153 edge e;
154 basic_block bb;
156 /* An obscure special case, where we do have partially dead
157 instruction scheduled after last control flow instruction.
158 In this case we can create new basic block. It is
159 always exactly one basic block last in the sequence. */
161 e = find_fallthru_edge (last_bb->succs);
163 gcc_checking_assert (!e || !(e->flags & EDGE_COMPLEX));
165 gcc_checking_assert (BLOCK_FOR_INSN (insn) == last_bb
166 && !IS_SPECULATION_CHECK_P (insn)
167 && BB_HEAD (last_bb) != insn
168 && BB_END (last_bb) == insn);
171 rtx_insn *x = NEXT_INSN (insn);
172 if (e)
173 gcc_checking_assert (NOTE_P (x) || LABEL_P (x));
174 else
175 gcc_checking_assert (BARRIER_P (x));
178 if (e)
180 bb = split_edge (e);
181 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (BB_END (bb)));
183 else
185 /* Create an empty unreachable block after the INSN. */
186 rtx_insn *next = NEXT_INSN (insn);
187 if (next && BARRIER_P (next))
188 next = NEXT_INSN (next);
189 bb = create_basic_block (next, NULL_RTX, last_bb);
192 /* split_edge () creates BB before E->DEST. Keep in mind, that
193 this operation extends scheduling region till the end of BB.
194 Hence, we need to shift NEXT_TAIL, so haifa-sched.c won't go out
195 of the scheduling region. */
196 current_sched_info->next_tail = NEXT_INSN (BB_END (bb));
197 gcc_assert (current_sched_info->next_tail);
199 /* Append new basic block to the end of the ebb. */
200 sched_init_only_bb (bb, last_bb);
201 gcc_assert (last_bb == bb);
205 /* Return a string that contains the insn uid and optionally anything else
206 necessary to identify this insn in an output. It's valid to use a
207 static buffer for this. The ALIGNED parameter should cause the string
208 to be formatted so that multiple output lines will line up nicely. */
210 static const char *
211 ebb_print_insn (const rtx_insn *insn, int aligned ATTRIBUTE_UNUSED)
213 static char tmp[80];
215 /* '+' before insn means it is a new cycle start. */
216 if (GET_MODE (insn) == TImode)
217 sprintf (tmp, "+ %4d", INSN_UID (insn));
218 else
219 sprintf (tmp, " %4d", INSN_UID (insn));
221 return tmp;
224 /* Compare priority of two insns. Return a positive number if the second
225 insn is to be preferred for scheduling, and a negative one if the first
226 is to be preferred. Zero if they are equally good. */
228 static int
229 rank (rtx_insn *insn1, rtx_insn *insn2)
231 basic_block bb1 = BLOCK_FOR_INSN (insn1);
232 basic_block bb2 = BLOCK_FOR_INSN (insn2);
234 if (bb1->count > bb2->count)
235 return -1;
236 if (bb1->count < bb2->count)
237 return 1;
238 return 0;
241 /* NEXT is an instruction that depends on INSN (a backward dependence);
242 return nonzero if we should include this dependence in priority
243 calculations. */
245 static int
246 ebb_contributes_to_priority (rtx_insn *next ATTRIBUTE_UNUSED,
247 rtx_insn *insn ATTRIBUTE_UNUSED)
249 return 1;
252 /* INSN is a JUMP_INSN. Store the set of registers that
253 must be considered as used by this jump in USED. */
255 void
256 ebb_compute_jump_reg_dependencies (rtx insn, regset used)
258 basic_block b = BLOCK_FOR_INSN (insn);
259 edge e;
260 edge_iterator ei;
262 FOR_EACH_EDGE (e, ei, b->succs)
263 if ((e->flags & EDGE_FALLTHRU) == 0)
264 bitmap_ior_into (used, df_get_live_in (e->dest));
267 /* Used in schedule_insns to initialize current_sched_info for scheduling
268 regions (or single basic blocks). */
270 static struct common_sched_info_def ebb_common_sched_info;
272 static struct sched_deps_info_def ebb_sched_deps_info =
274 ebb_compute_jump_reg_dependencies,
275 NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL, NULL,
276 NULL,
277 1, 0, 0
280 static struct haifa_sched_info ebb_sched_info =
282 init_ready_list,
283 NULL,
284 schedule_more_p,
285 NULL,
286 rank,
287 ebb_print_insn,
288 ebb_contributes_to_priority,
289 NULL, /* insn_finishes_block_p */
291 NULL, NULL,
292 NULL, NULL,
293 1, 0,
295 ebb_add_remove_insn,
296 begin_schedule_ready,
297 begin_move_insn,
298 advance_target_bb,
300 save_ebb_state,
301 restore_ebb_state,
303 SCHED_EBB
304 /* We can create new blocks in begin_schedule_ready (). */
305 | NEW_BBS
308 /* Returns the earliest block in EBB currently being processed where a
309 "similar load" 'insn2' is found, and hence LOAD_INSN can move
310 speculatively into the found block. All the following must hold:
312 (1) both loads have 1 base register (PFREE_CANDIDATEs).
313 (2) load_insn and load2 have a def-use dependence upon
314 the same insn 'insn1'.
316 From all these we can conclude that the two loads access memory
317 addresses that differ at most by a constant, and hence if moving
318 load_insn would cause an exception, it would have been caused by
319 load2 anyhow.
321 The function uses list (given by LAST_BLOCK) of already processed
322 blocks in EBB. The list is formed in `add_deps_for_risky_insns'. */
324 static basic_block
325 earliest_block_with_similiar_load (basic_block last_block, rtx load_insn)
327 sd_iterator_def back_sd_it;
328 dep_t back_dep;
329 basic_block bb, earliest_block = NULL;
331 FOR_EACH_DEP (load_insn, SD_LIST_BACK, back_sd_it, back_dep)
333 rtx_insn *insn1 = DEP_PRO (back_dep);
335 if (DEP_TYPE (back_dep) == REG_DEP_TRUE)
336 /* Found a DEF-USE dependence (insn1, load_insn). */
338 sd_iterator_def fore_sd_it;
339 dep_t fore_dep;
341 FOR_EACH_DEP (insn1, SD_LIST_FORW, fore_sd_it, fore_dep)
343 rtx_insn *insn2 = DEP_CON (fore_dep);
344 basic_block insn2_block = BLOCK_FOR_INSN (insn2);
346 if (DEP_TYPE (fore_dep) == REG_DEP_TRUE)
348 if (earliest_block != NULL
349 && earliest_block->index < insn2_block->index)
350 continue;
352 /* Found a DEF-USE dependence (insn1, insn2). */
353 if (haifa_classify_insn (insn2) != PFREE_CANDIDATE)
354 /* insn2 not guaranteed to be a 1 base reg load. */
355 continue;
357 for (bb = last_block; bb; bb = (basic_block) bb->aux)
358 if (insn2_block == bb)
359 break;
361 if (!bb)
362 /* insn2 is the similar load. */
363 earliest_block = insn2_block;
369 return earliest_block;
372 /* The following function adds dependencies between jumps and risky
373 insns in given ebb. */
375 static void
376 add_deps_for_risky_insns (rtx_insn *head, rtx_insn *tail)
378 rtx_insn *insn, *prev;
379 int classification;
380 rtx_insn *last_jump = NULL;
381 rtx_insn *next_tail = NEXT_INSN (tail);
382 basic_block last_block = NULL, bb;
384 for (insn = head; insn != next_tail; insn = NEXT_INSN (insn))
386 add_delay_dependencies (insn);
387 if (control_flow_insn_p (insn))
389 bb = BLOCK_FOR_INSN (insn);
390 bb->aux = last_block;
391 last_block = bb;
392 /* Ensure blocks stay in the same order. */
393 if (last_jump)
394 add_dependence (insn, last_jump, REG_DEP_ANTI);
395 last_jump = insn;
397 else if (INSN_P (insn) && last_jump != NULL_RTX)
399 classification = haifa_classify_insn (insn);
400 prev = last_jump;
402 switch (classification)
404 case PFREE_CANDIDATE:
405 if (flag_schedule_speculative_load)
407 bb = earliest_block_with_similiar_load (last_block, insn);
408 if (bb)
410 bb = (basic_block) bb->aux;
411 if (!bb)
412 break;
413 prev = BB_END (bb);
416 /* Fall through. */
417 case TRAP_RISKY:
418 case IRISKY:
419 case PRISKY_CANDIDATE:
420 /* ??? We could implement better checking PRISKY_CANDIDATEs
421 analogous to sched-rgn.c. */
422 /* We can not change the mode of the backward
423 dependency because REG_DEP_ANTI has the lowest
424 rank. */
425 if (! sched_insns_conditions_mutex_p (insn, prev))
427 if ((current_sched_info->flags & DO_SPECULATION)
428 && (spec_info->mask & BEGIN_CONTROL))
430 dep_def _dep, *dep = &_dep;
432 init_dep (dep, prev, insn, REG_DEP_ANTI);
434 if (current_sched_info->flags & USE_DEPS_LIST)
436 DEP_STATUS (dep) = set_dep_weak (DEP_ANTI, BEGIN_CONTROL,
437 MAX_DEP_WEAK);
440 sd_add_or_update_dep (dep, false);
442 else
443 add_dependence (insn, prev, REG_DEP_CONTROL);
446 break;
448 default:
449 break;
453 /* Maintain the invariant that bb->aux is clear after use. */
454 while (last_block)
456 bb = (basic_block) last_block->aux;
457 last_block->aux = NULL;
458 last_block = bb;
462 /* Schedule a single extended basic block, defined by the boundaries
463 HEAD and TAIL.
465 We change our expectations about scheduler behavior depending on
466 whether MODULO_SCHEDULING is true. If it is, we expect that the
467 caller has already called set_modulo_params and created delay pairs
468 as appropriate. If the modulo schedule failed, we return
469 NULL_RTX. */
471 basic_block
472 schedule_ebb (rtx_insn *head, rtx_insn *tail, bool modulo_scheduling)
474 basic_block first_bb, target_bb;
475 struct deps_desc tmp_deps;
476 bool success;
478 /* Blah. We should fix the rest of the code not to get confused by
479 a note or two. */
480 while (head != tail)
482 if (NOTE_P (head) || DEBUG_INSN_P (head))
483 head = NEXT_INSN (head);
484 else if (NOTE_P (tail) || DEBUG_INSN_P (tail))
485 tail = PREV_INSN (tail);
486 else if (LABEL_P (head))
487 head = NEXT_INSN (head);
488 else
489 break;
492 first_bb = BLOCK_FOR_INSN (head);
493 last_bb = BLOCK_FOR_INSN (tail);
495 if (no_real_insns_p (head, tail))
496 return BLOCK_FOR_INSN (tail);
498 gcc_assert (INSN_P (head) && INSN_P (tail));
500 if (!bitmap_bit_p (&dont_calc_deps, first_bb->index))
502 init_deps_global ();
504 /* Compute dependencies. */
505 init_deps (&tmp_deps, false);
506 sched_analyze (&tmp_deps, head, tail);
507 free_deps (&tmp_deps);
509 add_deps_for_risky_insns (head, tail);
511 if (targetm.sched.dependencies_evaluation_hook)
512 targetm.sched.dependencies_evaluation_hook (head, tail);
514 finish_deps_global ();
516 else
517 /* Only recovery blocks can have their dependencies already calculated,
518 and they always are single block ebbs. */
519 gcc_assert (first_bb == last_bb);
521 /* Set priorities. */
522 current_sched_info->sched_max_insns_priority = 0;
523 rgn_n_insns = set_priorities (head, tail);
524 current_sched_info->sched_max_insns_priority++;
526 current_sched_info->prev_head = PREV_INSN (head);
527 current_sched_info->next_tail = NEXT_INSN (tail);
529 remove_notes (head, tail);
531 unlink_bb_notes (first_bb, last_bb);
533 target_bb = first_bb;
535 /* Make ready list big enough to hold all the instructions from the ebb. */
536 sched_extend_ready_list (rgn_n_insns);
537 success = schedule_block (&target_bb, NULL);
538 gcc_assert (success || modulo_scheduling);
540 /* Free ready list. */
541 sched_finish_ready_list ();
543 /* We might pack all instructions into fewer blocks,
544 so we may made some of them empty. Can't assert (b == last_bb). */
546 /* Sanity check: verify that all region insns were scheduled. */
547 gcc_assert (modulo_scheduling || sched_rgn_n_insns == rgn_n_insns);
549 /* Free dependencies. */
550 sched_free_deps (current_sched_info->head, current_sched_info->tail, true);
552 gcc_assert (haifa_recovery_bb_ever_added_p
553 || deps_pools_are_empty_p ());
555 if (EDGE_COUNT (last_bb->preds) == 0)
556 /* LAST_BB is unreachable. */
558 gcc_assert (first_bb != last_bb
559 && EDGE_COUNT (last_bb->succs) == 0);
560 last_bb = last_bb->prev_bb;
561 delete_basic_block (last_bb->next_bb);
564 return success ? last_bb : NULL;
567 /* Perform initializations before running schedule_ebbs or a single
568 schedule_ebb. */
569 void
570 schedule_ebbs_init (void)
572 /* Setup infos. */
574 memcpy (&ebb_common_sched_info, &haifa_common_sched_info,
575 sizeof (ebb_common_sched_info));
577 ebb_common_sched_info.fix_recovery_cfg = ebb_fix_recovery_cfg;
578 ebb_common_sched_info.add_block = ebb_add_block;
579 ebb_common_sched_info.sched_pass_id = SCHED_EBB_PASS;
581 common_sched_info = &ebb_common_sched_info;
582 sched_deps_info = &ebb_sched_deps_info;
583 current_sched_info = &ebb_sched_info;
586 haifa_sched_init ();
588 compute_bb_for_insn ();
590 /* Initialize DONT_CALC_DEPS and ebb-{start, end} markers. */
591 bitmap_initialize (&dont_calc_deps, 0);
592 bitmap_clear (&dont_calc_deps);
595 /* Perform cleanups after scheduling using schedules_ebbs or schedule_ebb. */
596 void
597 schedule_ebbs_finish (void)
599 bitmap_clear (&dont_calc_deps);
601 /* Reposition the prologue and epilogue notes in case we moved the
602 prologue/epilogue insns. */
603 if (reload_completed)
604 reposition_prologue_and_epilogue_notes ();
606 haifa_sched_finish ();
609 /* The main entry point in this file. */
611 void
612 schedule_ebbs (void)
614 basic_block bb;
615 int probability_cutoff;
616 rtx_insn *tail;
618 /* Taking care of this degenerate case makes the rest of
619 this code simpler. */
620 if (n_basic_blocks_for_fn (cfun) == NUM_FIXED_BLOCKS)
621 return;
623 if (profile_info && profile_status_for_fn (cfun) == PROFILE_READ)
624 probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY_FEEDBACK);
625 else
626 probability_cutoff = PARAM_VALUE (TRACER_MIN_BRANCH_PROBABILITY);
627 probability_cutoff = REG_BR_PROB_BASE / 100 * probability_cutoff;
629 schedule_ebbs_init ();
631 /* Schedule every region in the subroutine. */
632 FOR_EACH_BB_FN (bb, cfun)
634 rtx_insn *head = BB_HEAD (bb);
636 if (bb->flags & BB_DISABLE_SCHEDULE)
637 continue;
639 for (;;)
641 edge e;
642 tail = BB_END (bb);
643 if (bb->next_bb == EXIT_BLOCK_PTR_FOR_FN (cfun)
644 || LABEL_P (BB_HEAD (bb->next_bb)))
645 break;
646 e = find_fallthru_edge (bb->succs);
647 if (! e)
648 break;
649 if (e->probability.initialized_p ()
650 && e->probability.to_reg_br_prob_base () <= probability_cutoff)
651 break;
652 if (e->dest->flags & BB_DISABLE_SCHEDULE)
653 break;
654 bb = bb->next_bb;
657 bb = schedule_ebb (head, tail, false);
659 schedule_ebbs_finish ();
662 /* INSN has been added to/removed from current ebb. */
663 static void
664 ebb_add_remove_insn (rtx_insn *insn ATTRIBUTE_UNUSED, int remove_p)
666 if (!remove_p)
667 rgn_n_insns++;
668 else
669 rgn_n_insns--;
672 /* BB was added to ebb after AFTER. */
673 static void
674 ebb_add_block (basic_block bb, basic_block after)
676 /* Recovery blocks are always bounded by BARRIERS,
677 therefore, they always form single block EBB,
678 therefore, we can use rec->index to identify such EBBs. */
679 if (after == EXIT_BLOCK_PTR_FOR_FN (cfun))
680 bitmap_set_bit (&dont_calc_deps, bb->index);
681 else if (after == last_bb)
682 last_bb = bb;
685 /* Return next block in ebb chain. For parameter meaning please refer to
686 sched-int.h: struct sched_info: advance_target_bb. */
687 static basic_block
688 advance_target_bb (basic_block bb, rtx_insn *insn)
690 if (insn)
692 if (BLOCK_FOR_INSN (insn) != bb
693 && control_flow_insn_p (insn)
694 /* We handle interblock movement of the speculation check
695 or over a speculation check in
696 haifa-sched.c: move_block_after_check (). */
697 && !IS_SPECULATION_BRANCHY_CHECK_P (insn)
698 && !IS_SPECULATION_BRANCHY_CHECK_P (BB_END (bb)))
700 /* Assert that we don't move jumps across blocks. */
701 gcc_assert (!control_flow_insn_p (BB_END (bb))
702 && NOTE_INSN_BASIC_BLOCK_P (BB_HEAD (bb->next_bb)));
703 return bb;
705 else
706 return 0;
708 else
709 /* Return next non empty block. */
713 gcc_assert (bb != last_bb);
715 bb = bb->next_bb;
717 while (bb_note (bb) == BB_END (bb));
719 return bb;
723 /* Fix internal data after interblock movement of jump instruction.
724 For parameter meaning please refer to
725 sched-int.h: struct sched_info: fix_recovery_cfg. */
726 static void
727 ebb_fix_recovery_cfg (int bbi ATTRIBUTE_UNUSED, int jump_bbi,
728 int jump_bb_nexti)
730 gcc_assert (last_bb->index != bbi);
732 if (jump_bb_nexti == last_bb->index)
733 last_bb = BASIC_BLOCK_FOR_FN (cfun, jump_bbi);
736 #endif /* INSN_SCHEDULING */