1 /* Basic block reordering routines for the GNU compiler.
2 Copyright (C) 2000 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
23 "Profile Guided Code Positioning"
24 Pettis and Hanson; PLDI '90.
30 if (p) goto A; // predict taken
33 if (q) goto B; // predict taken
39 We'll currently reorder this as
68 This requires that we be able to duplicate the jump at A, and
69 adjust the graph traversal such that greedy placement doesn't
70 fix D before C is considered.
72 (2) Coordinate with shorten_branches to minimize the number of
75 (3) Invent a method by which sufficiently non-predicted code can
76 be moved to either the end of the section or another section
77 entirely. Some sort of NOTE_INSN note would work fine.
79 This completely scroggs all debugging formats, so the user
80 would have to explicitly ask for it.
88 #include "hard-reg-set.h"
89 #include "basic-block.h"
90 #include "insn-config.h"
98 #include "insn-flags.h"
103 #ifndef HAVE_epilogue
104 #define HAVE_epilogue 0
108 /* The contents of the current function definition are allocated
109 in this obstack, and all are freed at the end of the function.
110 For top-level functions, this is temporary_obstack.
111 Separate obstacks are made for nested functions. */
113 extern struct obstack *function_obstack;
116 /* Structure to hold information about lexical scopes. */
117 typedef struct scope_def
121 /* The NOTE_INSN_BLOCK_BEG that started this scope. */
124 /* The NOTE_INSN_BLOCK_END that ended this scope. */
127 /* The bb containing note_beg (if any). */
130 /* The bb containing note_end (if any). */
133 /* List of basic blocks contained within this scope. */
136 /* Number of blocks contained within this scope. */
139 /* The outer scope or NULL if outermost scope. */
140 struct scope_def *outer;
142 /* The first inner scope or NULL if innermost scope. */
143 struct scope_def *inner;
145 /* The last inner scope or NULL if innermost scope. */
146 struct scope_def *inner_last;
148 /* Link to the next (sibling) scope. */
149 struct scope_def *next;
153 /* Structure to hold information about the scope forest. */
156 /* Number of trees in forest. */
159 /* List of tree roots. */
163 /* Structure to hold information about the blocks during reordering. */
164 typedef struct reorder_block_def
172 } *reorder_block_def;
174 #define RBI(BB) ((reorder_block_def) (BB)->aux)
177 /* Local function prototypes. */
178 static rtx skip_insns_after_block PARAMS ((basic_block));
179 static void record_effective_endpoints PARAMS ((void));
180 static void make_reorder_chain PARAMS ((void));
181 static basic_block make_reorder_chain_1 PARAMS ((basic_block, basic_block));
182 static rtx label_for_bb PARAMS ((basic_block));
183 static rtx emit_jump_to_block_after PARAMS ((basic_block, rtx));
184 static void fixup_reorder_chain PARAMS ((void));
185 static void relate_bbs_with_scopes PARAMS ((scope));
186 static scope make_new_scope PARAMS ((int, rtx));
187 static void build_scope_forest PARAMS ((scope_forest_info *));
188 static void remove_scope_notes PARAMS ((void));
189 static void insert_intra_1 PARAMS ((scope, rtx *));
190 static void insert_intra_bb_scope_notes PARAMS ((basic_block));
191 static void insert_inter_bb_scope_notes PARAMS ((basic_block, basic_block));
192 static void rebuild_scope_notes PARAMS ((scope_forest_info *));
193 static void free_scope_forest_1 PARAMS ((scope));
194 static void free_scope_forest PARAMS ((scope_forest_info *));
195 void dump_scope_forest PARAMS ((scope_forest_info *));
196 static void dump_scope_forest_1 PARAMS ((scope, int));
197 static rtx get_next_bb_note PARAMS ((rtx));
198 static rtx get_prev_bb_note PARAMS ((rtx));
200 void verify_insn_chain PARAMS ((void));
202 /* Skip over inter-block insns occurring after BB which are typically
203 associated with BB (e.g., barriers). If there are any such insns,
204 we return the last one. Otherwise, we return the end of BB. */
207 skip_insns_after_block (bb)
210 rtx insn, last_insn, next_head;
212 next_head = NULL_RTX;
213 if (bb->index + 1 != n_basic_blocks)
214 next_head = BASIC_BLOCK (bb->index + 1)->head;
216 for (last_insn = bb->end; (insn = NEXT_INSN (last_insn)); last_insn = insn)
218 if (insn == next_head)
221 switch (GET_CODE (insn))
227 switch (NOTE_LINE_NUMBER (insn))
229 case NOTE_INSN_LOOP_END:
230 case NOTE_INSN_BLOCK_END:
231 case NOTE_INSN_DELETED:
232 case NOTE_INSN_DELETED_LABEL:
242 && GET_CODE (NEXT_INSN (insn)) == JUMP_INSN
243 && (GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_VEC
244 || GET_CODE (PATTERN (NEXT_INSN (insn))) == ADDR_DIFF_VEC))
246 insn = NEXT_INSN (insn);
262 /* Locate the effective beginning and end of the insn chain for each
263 block, as defined by skip_insns_after_block above. */
266 record_effective_endpoints ()
268 rtx next_insn = get_insns ();
271 for (i = 0; i < n_basic_blocks; ++i)
273 basic_block bb = BASIC_BLOCK (i);
276 RBI (bb)->eff_head = next_insn;
277 end = skip_insns_after_block (bb);
278 RBI (bb)->eff_end = end;
279 next_insn = NEXT_INSN (end);
284 /* Compute an ordering for a subgraph beginning with block BB. Record the
285 ordering in RBI()->index and chained through RBI()->next. */
288 make_reorder_chain ()
290 basic_block last_block = NULL;
291 basic_block prev = NULL;
292 int nbb_m1 = n_basic_blocks - 1;
294 /* If we've not got epilogue in RTL, we must fallthru to the exit.
295 Force the last block to be at the end. */
296 /* ??? Some ABIs (e.g. MIPS) require the return insn to be at the
297 end of the function for stack unwinding purposes. */
300 last_block = BASIC_BLOCK (nbb_m1);
301 RBI (last_block)->visited = 1;
305 /* Loop until we've placed every block. */
309 basic_block next = NULL;
311 /* Find the next unplaced block. */
312 /* ??? Get rid of this loop, and track which blocks are not yet
313 placed more directly, so as to avoid the O(N^2) worst case.
314 Perhaps keep a doubly-linked list of all to-be-placed blocks;
315 remove from the list as we place. The head of that list is
316 what we're looking for here. */
318 for (i = 0; i <= nbb_m1; ++i)
320 basic_block bb = BASIC_BLOCK (i);
321 if (! RBI (bb)->visited)
330 prev = make_reorder_chain_1 (next, prev);
332 while (RBI (prev)->index < nbb_m1);
334 /* Terminate the chain. */
337 RBI (prev)->next = last_block;
338 RBI (last_block)->index = RBI (prev)->index + 1;
341 RBI (prev)->next = NULL;
344 /* A helper function for make_reorder_chain.
346 We do not follow EH edges, or non-fallthru edges to noreturn blocks.
347 These are assumed to be the error condition and we wish to cluster
348 all of them at the very end of the function for the benefit of cache
349 locality for the rest of the function.
351 ??? We could do slightly better by noticing earlier that some subgraph
352 has all paths leading to noreturn functions, but for there to be more
353 than one block in such a subgraph is rare. */
356 make_reorder_chain_1 (bb, prev)
364 /* Mark this block visited. */
370 RBI (prev)->next = bb;
371 new_index = RBI (prev)->index + 1;
372 RBI (bb)->index = new_index;
374 if (rtl_dump_file && prev->index + 1 != bb->index)
375 fprintf (rtl_dump_file, "Reordering block %d (%d) after %d (%d)\n",
376 bb->index, RBI (bb)->index, prev->index, RBI (prev)->index);
380 RBI (bb)->visited = 1;
383 if (bb->succ == NULL)
386 /* Find the most probable block. */
389 if (any_condjump_p (bb->end)
390 && (note = find_reg_note (bb->end, REG_BR_PROB, 0)) != NULL)
392 int taken, probability;
393 edge e_taken, e_fall;
395 probability = INTVAL (XEXP (note, 0));
396 taken = probability > REG_BR_PROB_BASE / 2;
398 /* Find the normal taken edge and the normal fallthru edge.
399 Note that there may in fact be other edges due to
400 asynchronous_exceptions. */
402 e_taken = e_fall = NULL;
403 for (e = bb->succ; e ; e = e->succ_next)
404 if (e->flags & EDGE_FALLTHRU)
406 else if (! (e->flags & EDGE_EH))
409 next = (taken ? e_taken : e_fall)->dest;
412 /* In the absence of a prediction, disturb things as little as possible
413 by selecting the old "next" block from the list of successors. If
414 there had been a fallthru edge, that will be the one. */
417 for (e = bb->succ; e ; e = e->succ_next)
418 if (e->dest->index == bb->index + 1)
420 if ((e->flags & EDGE_FALLTHRU)
422 && ! (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))))
428 /* Make sure we didn't select a silly next block. */
429 if (! next || next == EXIT_BLOCK_PTR || RBI (next)->visited)
432 /* Recurse on the successors. Unroll the last call, as the normal
433 case is exactly one or two edges, and we can tail recurse. */
434 for (e = bb->succ; e; e = e->succ_next)
435 if (e->dest != EXIT_BLOCK_PTR
436 && ! RBI (e->dest)->visited
438 && ! (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH)))
442 prev = make_reorder_chain_1 (next, prev);
443 next = RBI (e->dest)->visited ? NULL : e->dest;
458 /* Locate or create a label for a given basic block. */
464 rtx label = bb->head;
466 if (GET_CODE (label) != CODE_LABEL)
469 fprintf (rtl_dump_file, "Emitting label for block %d (%d)\n",
470 bb->index, RBI (bb)->index);
472 label = emit_label_before (gen_label_rtx (), label);
473 if (bb->head == RBI (bb)->eff_head)
474 RBI (bb)->eff_head = label;
482 /* Emit a jump to BB after insn AFTER. */
485 emit_jump_to_block_after (bb, after)
491 if (bb != EXIT_BLOCK_PTR)
493 rtx label = label_for_bb (bb);
494 jump = emit_jump_insn_after (gen_jump (label), after);
495 JUMP_LABEL (jump) = label;
496 LABEL_NUSES (label) += 1;
499 fprintf (rtl_dump_file, "Emitting jump to block %d (%d)\n",
500 bb->index, RBI (bb)->index);
507 jump = emit_jump_insn_after (gen_return (), after);
510 fprintf (rtl_dump_file, "Emitting return\n");
520 /* Given a reorder chain, rearrange the code to match. */
523 fixup_reorder_chain ()
525 basic_block bb, last_bb;
527 /* First do the bulk reordering -- rechain the blocks without regard to
528 the needed changes to jumps and labels. */
530 last_bb = BASIC_BLOCK (0);
531 bb = RBI (last_bb)->next;
534 rtx last_e = RBI (last_bb)->eff_end;
535 rtx curr_h = RBI (bb)->eff_head;
537 NEXT_INSN (last_e) = curr_h;
538 PREV_INSN (curr_h) = last_e;
543 NEXT_INSN (RBI (last_bb)->eff_end) = NULL_RTX;
544 set_last_insn (RBI (last_bb)->eff_end);
546 /* Now add jumps and labels as needed to match the blocks new
549 for (bb = BASIC_BLOCK (0); bb ; bb = RBI (bb)->next)
551 edge e_fall, e_taken, e;
552 rtx jump_insn, barrier_insn;
555 if (bb->succ == NULL)
558 /* Find the old fallthru edge, and another non-EH edge for
560 e_taken = e_fall = NULL;
561 for (e = bb->succ; e ; e = e->succ_next)
562 if (e->flags & EDGE_FALLTHRU)
564 else if (! (e->flags & EDGE_EH))
567 if (GET_CODE (bb->end) == JUMP_INSN)
569 if (any_uncondjump_p (bb->end))
571 /* If the destination is still not next, nothing to do. */
572 if (RBI (bb)->index + 1 != RBI (e_taken->dest)->index)
575 /* Otherwise, we can remove the jump and cleanup the edge. */
576 tidy_fallthru_edge (e_taken, bb, e_taken->dest);
577 RBI (bb)->eff_end = skip_insns_after_block (bb);
578 RBI (e_taken->dest)->eff_head = NEXT_INSN (RBI (bb)->eff_end);
581 fprintf (rtl_dump_file, "Removing jump in block %d (%d)\n",
582 bb->index, RBI (bb)->index);
585 else if (any_condjump_p (bb->end))
587 /* If the old fallthru is still next, nothing to do. */
588 if (RBI (bb)->index + 1 == RBI (e_fall->dest)->index
589 || (RBI (bb)->index == n_basic_blocks - 1
590 && e_fall->dest == EXIT_BLOCK_PTR))
593 /* There is one special case: if *neither* block is next,
594 such as happens at the very end of a function, then we'll
595 need to add a new unconditional jump. Choose the taken
596 edge based on known or assumed probability. */
597 if (RBI (bb)->index + 1 != RBI (e_taken->dest)->index)
599 rtx note = find_reg_note (bb->end, REG_BR_PROB, 0);
601 && INTVAL (XEXP (note, 0)) < REG_BR_PROB_BASE / 2
602 && invert_jump (bb->end, label_for_bb (e_fall->dest), 0))
604 e_fall->flags &= ~EDGE_FALLTHRU;
605 e_taken->flags |= EDGE_FALLTHRU;
606 e = e_fall, e_fall = e_taken, e_taken = e;
610 /* Otherwise we can try to invert the jump. This will
611 basically never fail, however, keep up the pretense. */
612 else if (invert_jump (bb->end, label_for_bb (e_fall->dest), 0))
614 e_fall->flags &= ~EDGE_FALLTHRU;
615 e_taken->flags |= EDGE_FALLTHRU;
619 else if (returnjump_p (bb->end))
623 /* Otherwise we have some switch or computed jump. In the
624 99% case, there should not have been a fallthru edge. */
627 #ifdef CASE_DROPS_THROUGH
628 /* Except for VAX. Since we didn't have predication for the
629 tablejump, the fallthru block should not have moved. */
630 if (RBI (bb)->index + 1 == RBI (e_fall->dest)->index)
638 /* No fallthru implies a noreturn function with EH edges, or
639 something similarly bizarre. In any case, we don't need to
644 /* If the fallthru block is still next, nothing to do. */
645 if (RBI (bb)->index + 1 == RBI (e_fall->dest)->index
646 || (RBI (bb)->index == n_basic_blocks - 1
647 && e_fall->dest == EXIT_BLOCK_PTR))
650 /* We need a new jump insn. If the block has only one outgoing
651 edge, then we can stuff the new jump insn in directly. */
652 if (bb->succ->succ_next == NULL)
654 e_fall->flags &= ~EDGE_FALLTHRU;
656 jump_insn = emit_jump_to_block_after (e_fall->dest, bb->end);
658 barrier_insn = emit_barrier_after (jump_insn);
659 RBI (bb)->eff_end = barrier_insn;
664 /* We got here if we need to add a new jump insn in a new block
665 across the edge e_fall. */
667 jump_insn = emit_jump_to_block_after (e_fall->dest, bb->end);
668 barrier_insn = emit_barrier_after (jump_insn);
670 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
671 create_basic_block (n_basic_blocks - 1, jump_insn, jump_insn, NULL);
673 nb = BASIC_BLOCK (n_basic_blocks - 1);
674 nb->global_live_at_start = OBSTACK_ALLOC_REG_SET (function_obstack);
675 nb->global_live_at_end = OBSTACK_ALLOC_REG_SET (function_obstack);
678 COPY_REG_SET (nb->global_live_at_start, bb->global_live_at_start);
679 COPY_REG_SET (nb->global_live_at_end, bb->global_live_at_start);
681 nb->aux = xmalloc (sizeof (struct reorder_block_def));
682 RBI (nb)->eff_head = nb->head;
683 RBI (nb)->eff_end = barrier_insn;
684 RBI (nb)->scope = RBI (bb)->scope;
685 RBI (nb)->index = RBI (bb)->index + 1;
686 RBI (nb)->visited = 1;
687 RBI (nb)->next = RBI (bb)->next;
690 /* Link to new block. */
691 make_edge (NULL, nb, e_fall->dest, 0);
692 redirect_edge_succ (e_fall, nb);
694 /* Don't process this new block. */
697 /* Fix subsequent reorder block indices to reflect new block. */
698 while ((nb = RBI (nb)->next) != NULL)
699 RBI (nb)->index += 1;
702 /* Put basic_block_info in the new order. */
703 for (bb = BASIC_BLOCK (0); bb ; bb = RBI (bb)->next)
705 bb->index = RBI (bb)->index;
706 BASIC_BLOCK (bb->index) = bb;
711 /* Perform sanity checks on the insn chain.
712 1. Check that next/prev pointers are consistent in both the forward and
714 2. Count insns in chain, going both directions, and check if equal.
715 3. Check that get_last_insn () returns the actual end of chain. */
728 for (x = get_insns (); x; x = NEXT_INSN (x))
730 if (PREV_INSN (x) != prevx)
732 fprintf (stderr, "Forward traversal: insn chain corrupt.\n");
733 fprintf (stderr, "previous insn:\n");
735 fprintf (stderr, "current insn:\n");
743 if (prevx != get_last_insn ())
745 fprintf (stderr, "last_insn corrupt.\n");
751 for (x = get_last_insn (); x; x = PREV_INSN (x))
753 if (NEXT_INSN (x) != nextx)
755 fprintf (stderr, "Reverse traversal: insn chain corrupt.\n");
756 fprintf (stderr, "current insn:\n");
758 fprintf (stderr, "next insn:\n");
766 if (insn_cnt1 != insn_cnt2)
768 fprintf (stderr, "insn_cnt1 (%d) not equal to insn_cnt2 (%d).\n",
769 insn_cnt1, insn_cnt2);
780 if (NOTE_INSN_BASIC_BLOCK_P (x))
794 if (NOTE_INSN_BASIC_BLOCK_P (x))
802 /* Determine and record the relationships between basic blocks and
803 scopes in scope tree S. */
806 relate_bbs_with_scopes (s)
810 int i, bbi1, bbi2, bbs_spanned;
813 for (p = s->inner; p; p = p->next)
814 relate_bbs_with_scopes (p);
819 /* If the begin and end notes are both inside the same basic block,
820 or if they are both outside of basic blocks, then we know immediately
821 how they are related. Otherwise, we need to poke around to make the
823 if (s->bb_beg != s->bb_end)
825 if (s->bb_beg && s->bb_end)
827 /* Both notes are in different bbs. This implies that all the
828 basic blocks spanned by the pair of notes are contained in
830 bbi1 = s->bb_beg->index;
831 bbi2 = s->bb_end->index;
834 else if (! s->bb_beg)
836 /* First note is outside of a bb. If the scope spans more than
837 one basic block, then they all are contained within this
838 scope. Otherwise, this scope is contained within the basic
840 bbnote = get_next_bb_note (s->note_beg);
843 if (NOTE_BASIC_BLOCK (bbnote) == s->bb_end)
846 s->bb_beg = NOTE_BASIC_BLOCK (bbnote);
850 bbi1 = NOTE_BASIC_BLOCK (bbnote)->index;
851 bbi2 = s->bb_end->index;
856 else /* ! s->bb_end */
858 /* Second note is outside of a bb. If the scope spans more than
859 one basic block, then they all are contained within this
860 scope. Otherwise, this scope is contained within the basic
862 bbnote = get_prev_bb_note (s->note_end);
865 if (NOTE_BASIC_BLOCK (bbnote) == s->bb_beg)
868 s->bb_end = NOTE_BASIC_BLOCK (bbnote);
872 bbi1 = s->bb_beg->index;
873 bbi2 = NOTE_BASIC_BLOCK (bbnote)->index;
882 /* Both notes are in the same bb, which implies the block
883 contains this scope. */
888 /* Both notes are outside of any bbs. This implies that all the
889 basic blocks spanned by the pair of notes are contained in
891 There is a degenerate case to consider. If the notes do not
892 span any basic blocks, then it is an empty scope that can
893 safely be deleted or ignored. Mark these with level = -1. */
895 x1 = get_next_bb_note (s->note_beg);
896 x2 = get_prev_bb_note (s->note_end);
904 bbi1 = NOTE_BASIC_BLOCK (x1)->index;
905 bbi2 = NOTE_BASIC_BLOCK (x2)->index;
911 /* If the scope spans one or more basic blocks, we record them. We
912 only record the bbs that are immediately contained within this
913 scope. Note that if a scope is contained within a bb, we can tell
914 by checking that bb_beg = bb_end and that they are non-null. */
920 for (i = bbi1; i <= bbi2; i++)
921 if (! RBI (BASIC_BLOCK (i))->scope)
924 s->bbs = xmalloc (s->num_bbs * sizeof (basic_block));
925 for (i = bbi1; i <= bbi2; i++)
927 basic_block curr_bb = BASIC_BLOCK (i);
928 if (! RBI (curr_bb)->scope)
930 s->bbs[j++] = curr_bb;
931 RBI (curr_bb)->scope = s;
940 /* Allocate and initialize a new scope structure with scope level LEVEL,
941 and record the NOTE beginning the scope. */
944 make_new_scope (level, note)
948 scope new_scope = xcalloc (1, sizeof (struct scope_def));
949 new_scope->level = level;
950 new_scope->note_beg = note;
955 /* Build a forest representing the scope structure of the function.
956 Return a pointer to a structure describing the forest. */
959 build_scope_forest (forest)
960 scope_forest_info *forest;
965 scope root, curr_scope = 0;
967 forest->num_trees = 0;
968 forest->trees = NULL;
973 for (x = get_insns (); x; x = NEXT_INSN (x))
975 if (bbi < n_basic_blocks && x == BASIC_BLOCK (bbi)->head)
976 curr_bb = BASIC_BLOCK (bbi);
978 if (GET_CODE (x) == NOTE)
980 if (NOTE_LINE_NUMBER (x) == NOTE_INSN_BLOCK_BEG)
988 new_scope = make_new_scope (level, x);
989 new_scope->outer = curr_scope;
990 new_scope->next = NULL;
991 if (! curr_scope->inner)
993 curr_scope->inner = new_scope;
994 curr_scope->inner_last = new_scope;
998 curr_scope->inner_last->next = new_scope;
999 curr_scope->inner_last = new_scope;
1001 curr_scope = curr_scope->inner_last;
1005 int ntrees = forest->num_trees;
1007 curr_scope = make_new_scope (level, x);
1009 forest->trees = xrealloc (forest->trees,
1010 sizeof (scope) * (ntrees + 1));
1011 forest->trees[forest->num_trees++] = root;
1013 curr_scope->bb_beg = curr_bb;
1015 else if (NOTE_LINE_NUMBER (x) == NOTE_INSN_BLOCK_END)
1017 curr_scope->bb_end = curr_bb;
1018 curr_scope->note_end = x;
1020 curr_scope = curr_scope->outer;
1026 if (curr_bb && curr_bb->end == x)
1034 for (i = 0; i < forest->num_trees; i++)
1035 relate_bbs_with_scopes (forest->trees[i]);
1039 /* Remove all the NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes from
1043 remove_scope_notes ()
1046 basic_block currbb = NULL;
1048 for (x = get_insns (); x; x = next)
1050 next = NEXT_INSN (x);
1051 if (NOTE_INSN_BASIC_BLOCK_P (x))
1052 currbb = NOTE_BASIC_BLOCK (x);
1054 if (GET_CODE (x) == NOTE
1055 && (NOTE_LINE_NUMBER (x) == NOTE_INSN_BLOCK_BEG
1056 || NOTE_LINE_NUMBER (x) == NOTE_INSN_BLOCK_END))
1058 /* Check if the scope note happens to be the end of a bb. */
1059 if (currbb && x == currbb->end)
1060 currbb->end = PREV_INSN (x);
1061 if (currbb && x == currbb->head)
1066 NEXT_INSN (PREV_INSN (x)) = next;
1067 PREV_INSN (next) = PREV_INSN (x);
1069 NEXT_INSN (x) = NULL;
1070 PREV_INSN (x) = NULL;
1079 /* Insert scope note pairs for a contained scope tree S after insn IP. */
1082 insert_intra_1 (s, ip)
1088 if (NOTE_BLOCK (s->note_beg))
1090 *ip = emit_note_after (NOTE_INSN_BLOCK_BEG, *ip);
1091 NOTE_BLOCK (*ip) = NOTE_BLOCK (s->note_beg);
1094 for (p = s->inner; p; p = p->next)
1095 insert_intra_1 (p, ip);
1097 if (NOTE_BLOCK (s->note_beg))
1099 *ip = emit_note_after (NOTE_INSN_BLOCK_END, *ip);
1100 NOTE_BLOCK (*ip) = NOTE_BLOCK (s->note_end);
1105 /* Insert NOTE_INSN_BLOCK_END notes and NOTE_INSN_BLOCK_BEG notes for
1106 scopes that are contained within BB. */
1109 insert_intra_bb_scope_notes (bb)
1112 scope s = RBI (bb)->scope;
1120 if (GET_CODE (ip) == CODE_LABEL)
1121 ip = NEXT_INSN (ip);
1123 for (p = s->inner; p; p = p->next)
1125 if (p->bb_beg != NULL && p->bb_beg == p->bb_end && p->bb_beg == bb)
1126 insert_intra_1 (p, &ip);
1131 /* Given two consecutive basic blocks BB1 and BB2 with different scopes,
1132 insert NOTE_INSN_BLOCK_END notes after BB1 and NOTE_INSN_BLOCK_BEG
1133 notes before BB2 such that the notes are correctly balanced. If BB1 or
1134 BB2 is NULL, we are inserting scope notes for the first and last basic
1135 blocks, respectively. */
1138 insert_inter_bb_scope_notes (bb1, bb2)
1145 /* It is possible that a basic block is not contained in any scope.
1146 In that case, we either open or close a scope but not both. */
1149 scope s1 = RBI (bb1)->scope;
1150 scope s2 = RBI (bb2)->scope;
1159 /* Find common ancestor scope. */
1162 scope s1 = RBI (bb1)->scope;
1163 scope s2 = RBI (bb2)->scope;
1168 if (s1->level > s2->level)
1170 else if (s2->level > s1->level)
1186 scope s = RBI (bb1)->scope;
1187 ip = RBI (bb1)->eff_end;
1190 if (NOTE_BLOCK (s->note_beg))
1192 ip = emit_note_after (NOTE_INSN_BLOCK_END, ip);
1193 NOTE_BLOCK (ip) = NOTE_BLOCK (s->note_end);
1202 scope s = RBI (bb2)->scope;
1206 if (NOTE_BLOCK (s->note_beg))
1208 ip = emit_note_before (NOTE_INSN_BLOCK_BEG, ip);
1209 NOTE_BLOCK (ip) = NOTE_BLOCK (s->note_beg);
1217 /* Rebuild all the NOTE_INSN_BLOCK_BEG and NOTE_INSN_BLOCK_END notes based
1218 on the scope forest and the newly reordered basic blocks. */
1221 rebuild_scope_notes (forest)
1222 scope_forest_info *forest;
1226 if (forest->num_trees == 0)
1229 /* Start by opening the scopes before the first basic block. */
1230 insert_inter_bb_scope_notes (NULL, BASIC_BLOCK (0));
1232 /* Then, open and close scopes as needed between blocks. */
1233 for (i = 0; i < n_basic_blocks - 1; i++)
1235 basic_block bb1 = BASIC_BLOCK (i);
1236 basic_block bb2 = BASIC_BLOCK (i + 1);
1237 if (RBI (bb1)->scope != RBI (bb2)->scope)
1238 insert_inter_bb_scope_notes (bb1, bb2);
1239 insert_intra_bb_scope_notes (bb1);
1242 /* Finally, close the scopes after the last basic block. */
1243 insert_inter_bb_scope_notes (BASIC_BLOCK (n_basic_blocks - 1), NULL);
1244 insert_intra_bb_scope_notes (BASIC_BLOCK (n_basic_blocks - 1));
1248 /* Free the storage associated with the scope tree at S. */
1251 free_scope_forest_1 (s)
1256 for (p = s->inner; p; p = next)
1259 free_scope_forest_1 (p);
1268 /* Free the storage associated with the scope forest. */
1271 free_scope_forest (forest)
1272 scope_forest_info *forest;
1275 for (i = 0; i < forest->num_trees; i++)
1276 free_scope_forest_1 (forest->trees[i]);
1280 /* Visualize the scope forest. */
1283 dump_scope_forest (forest)
1284 scope_forest_info *forest;
1286 if (forest->num_trees == 0)
1287 fprintf (stderr, "\n< Empty scope forest >\n");
1291 fprintf (stderr, "\n< Scope forest >\n");
1292 for (i = 0; i < forest->num_trees; i++)
1293 dump_scope_forest_1 (forest->trees[i], 0);
1298 /* Recursive portion of dump_scope_forest. */
1301 dump_scope_forest_1 (s, indent)
1308 if (s->bb_beg != NULL && s->bb_beg == s->bb_end
1309 && RBI (s->bb_beg)->scope
1310 && RBI (s->bb_beg)->scope->level + 1 == s->level)
1312 fprintf (stderr, "%*s", indent, "");
1313 fprintf (stderr, "BB%d:\n", s->bb_beg->index);
1316 fprintf (stderr, "%*s", indent, "");
1317 fprintf (stderr, "{ level %d (block %p)\n", s->level,
1318 (PTR) NOTE_BLOCK (s->note_beg));
1320 fprintf (stderr, "%*s%s", indent, "", "bbs:");
1321 for (i = 0; i < s->num_bbs; i++)
1322 fprintf (stderr, " %d", s->bbs[i]->index);
1323 fprintf (stderr, "\n");
1325 for (p = s->inner; p; p = p->next)
1326 dump_scope_forest_1 (p, indent + 2);
1328 fprintf (stderr, "%*s", indent, "");
1329 fprintf (stderr, "}\n");
1333 /* Reorder basic blocks. The main entry point to this file. */
1336 reorder_basic_blocks ()
1338 scope_forest_info forest;
1341 if (n_basic_blocks <= 1)
1344 /* We do not currently handle correct re-placement of EH notes. */
1345 for (i = 0; i < n_basic_blocks; i++)
1348 for (e = BASIC_BLOCK (i)->succ; e ; e = e->succ_next)
1349 if (e->flags & EDGE_EH)
1353 for (i = 0; i < n_basic_blocks; i++)
1354 BASIC_BLOCK (i)->aux = xcalloc (1, sizeof (struct reorder_block_def));
1356 build_scope_forest (&forest);
1357 remove_scope_notes ();
1359 record_effective_endpoints ();
1360 make_reorder_chain ();
1361 fixup_reorder_chain ();
1363 #ifdef ENABLE_CHECKING
1364 verify_insn_chain ();
1367 rebuild_scope_notes (&forest);
1368 free_scope_forest (&forest);
1371 for (i = 0; i < n_basic_blocks; i++)
1372 free (BASIC_BLOCK (i)->aux);
1374 #ifdef ENABLE_CHECKING
1375 verify_flow_info ();