1 /* Control flow graph manipulation code for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains low level functions to manipulate the CFG and analyze it
23 that are aware of the RTL intermediate language.
25 Available functionality:
26 - Basic CFG/RTL manipulation API documented in cfghooks.h
27 - CFG-aware instruction chain manipulation
28 delete_insn, delete_insn_chain
29 - Edge splitting and committing to edges
30 insert_insn_on_edge, commit_edge_insertions
31 - CFG updating after insn simplification
32 purge_dead_edges, purge_all_dead_edges
34 Functions not supposed for generic use:
35 - Infrastructure to determine quickly basic block for insn
36 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
37 - Edge redirection with updating and optimizing of insn chain
38 block_label, tidy_fallthru_edge, force_nonfallthru */
42 #include "coretypes.h"
46 #include "hard-reg-set.h"
47 #include "basic-block.h"
56 #include "insn-config.h"
57 #include "cfglayout.h"
61 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
62 /* ??? Should probably be using LABEL_NUSES instead. It would take a
63 bit of surgery to be able to use or co-opt the routines in jump. */
66 static int can_delete_note_p (rtx);
67 static int can_delete_label_p (rtx);
68 static void commit_one_edge_insertion (edge, int);
69 static rtx last_loop_beg_note (rtx);
70 static bool back_edge_of_syntactic_loop_p (basic_block, basic_block);
71 basic_block force_nonfallthru_and_redirect (edge, basic_block);
72 static basic_block rtl_split_edge (edge);
73 static bool rtl_move_block_after (basic_block, basic_block);
74 static int rtl_verify_flow_info (void);
75 static basic_block cfg_layout_split_block (basic_block, void *);
76 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
77 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
78 static void cfg_layout_delete_block (basic_block);
79 static void rtl_delete_block (basic_block);
80 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
81 static edge rtl_redirect_edge_and_branch (edge, basic_block);
82 static basic_block rtl_split_block (basic_block, void *);
83 static void rtl_dump_bb (basic_block, FILE *, int);
84 static int rtl_verify_flow_info_1 (void);
85 static void mark_killed_regs (rtx, rtx, void *);
86 static void rtl_make_forwarder_block (edge);
88 /* Return true if NOTE is not one of the ones that must be kept paired,
89 so that we may simply delete it. */
92 can_delete_note_p (rtx note)
94 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
95 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK
96 || NOTE_LINE_NUMBER (note) == NOTE_INSN_UNLIKELY_EXECUTED_CODE
97 || NOTE_LINE_NUMBER (note) == NOTE_INSN_PREDICTION);
100 /* True if a given label can be deleted. */
103 can_delete_label_p (rtx label)
105 return (!LABEL_PRESERVE_P (label)
106 /* User declared labels must be preserved. */
107 && LABEL_NAME (label) == 0
108 && !in_expr_list_p (forced_labels, label)
109 && !in_expr_list_p (label_value_list, label));
112 /* Delete INSN by patching it out. Return the next insn. */
115 delete_insn (rtx insn)
117 rtx next = NEXT_INSN (insn);
119 bool really_delete = true;
121 if (GET_CODE (insn) == CODE_LABEL)
123 /* Some labels can't be directly removed from the INSN chain, as they
124 might be references via variables, constant pool etc.
125 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
126 if (! can_delete_label_p (insn))
128 const char *name = LABEL_NAME (insn);
130 really_delete = false;
131 PUT_CODE (insn, NOTE);
132 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
133 NOTE_SOURCE_FILE (insn) = name;
136 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
141 /* If this insn has already been deleted, something is very wrong. */
142 if (INSN_DELETED_P (insn))
145 INSN_DELETED_P (insn) = 1;
148 /* If deleting a jump, decrement the use count of the label. Deleting
149 the label itself should happen in the normal course of block merging. */
150 if (GET_CODE (insn) == JUMP_INSN
152 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
153 LABEL_NUSES (JUMP_LABEL (insn))--;
155 /* Also if deleting an insn that references a label. */
158 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
159 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
161 LABEL_NUSES (XEXP (note, 0))--;
162 remove_note (insn, note);
166 if (GET_CODE (insn) == JUMP_INSN
167 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
168 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
170 rtx pat = PATTERN (insn);
171 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
172 int len = XVECLEN (pat, diff_vec_p);
175 for (i = 0; i < len; i++)
177 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
179 /* When deleting code in bulk (e.g. removing many unreachable
180 blocks) we can delete a label that's a target of the vector
181 before deleting the vector itself. */
182 if (GET_CODE (label) != NOTE)
183 LABEL_NUSES (label)--;
190 /* Like delete_insn but also purge dead edges from BB. */
192 delete_insn_and_edges (rtx insn)
198 && BLOCK_FOR_INSN (insn)
199 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
201 x = delete_insn (insn);
203 purge_dead_edges (BLOCK_FOR_INSN (insn));
207 /* Unlink a chain of insns between START and FINISH, leaving notes
208 that must be paired. */
211 delete_insn_chain (rtx start, rtx finish)
215 /* Unchain the insns one by one. It would be quicker to delete all of these
216 with a single unchaining, rather than one at a time, but we need to keep
220 next = NEXT_INSN (start);
221 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
224 next = delete_insn (start);
232 /* Like delete_insn but also purge dead edges from BB. */
234 delete_insn_chain_and_edges (rtx first, rtx last)
239 && BLOCK_FOR_INSN (last)
240 && BB_END (BLOCK_FOR_INSN (last)) == last)
242 delete_insn_chain (first, last);
244 purge_dead_edges (BLOCK_FOR_INSN (last));
247 /* Create a new basic block consisting of the instructions between HEAD and END
248 inclusive. This function is designed to allow fast BB construction - reuses
249 the note and basic block struct in BB_NOTE, if any and do not grow
250 BASIC_BLOCK chain and should be used directly only by CFG construction code.
251 END can be NULL in to create new empty basic block before HEAD. Both END
252 and HEAD can be NULL to create basic block at the end of INSN chain.
253 AFTER is the basic block we should be put after. */
256 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
261 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
264 /* If we found an existing note, thread it back onto the chain. */
268 if (GET_CODE (head) == CODE_LABEL)
272 after = PREV_INSN (head);
276 if (after != bb_note && NEXT_INSN (after) != bb_note)
277 reorder_insns_nobb (bb_note, bb_note, after);
281 /* Otherwise we must create a note and a basic block structure. */
287 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
288 else if (GET_CODE (head) == CODE_LABEL && end)
290 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
296 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
302 NOTE_BASIC_BLOCK (bb_note) = bb;
305 /* Always include the bb note in the block. */
306 if (NEXT_INSN (end) == bb_note)
311 bb->index = last_basic_block++;
313 link_block (bb, after);
314 BASIC_BLOCK (bb->index) = bb;
315 update_bb_for_insn (bb);
316 bb->partition = UNPARTITIONED;
318 /* Tag the block so that we know it has been used when considering
319 other basic block notes. */
325 /* Create new basic block consisting of instructions in between HEAD and END
326 and place it to the BB chain after block AFTER. END can be NULL in to
327 create new empty basic block before HEAD. Both END and HEAD can be NULL to
328 create basic block at the end of INSN chain. */
331 rtl_create_basic_block (void *headp, void *endp, basic_block after)
333 rtx head = headp, end = endp;
336 /* Grow the basic block array if needed. */
337 if ((size_t) last_basic_block >= VARRAY_SIZE (basic_block_info))
339 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
340 VARRAY_GROW (basic_block_info, new_size);
345 bb = create_basic_block_structure (head, end, NULL, after);
351 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
353 basic_block newbb = rtl_create_basic_block (head, end, after);
355 initialize_bb_rbi (newbb);
359 /* Delete the insns in a (non-live) block. We physically delete every
360 non-deleted-note insn, and update the flow graph appropriately.
362 Return nonzero if we deleted an exception handler. */
364 /* ??? Preserving all such notes strikes me as wrong. It would be nice
365 to post-process the stream to remove empty blocks, loops, ranges, etc. */
368 rtl_delete_block (basic_block b)
372 /* If the head of this block is a CODE_LABEL, then it might be the
373 label for an exception handler which can't be reached.
375 We need to remove the label from the exception_handler_label list
376 and remove the associated NOTE_INSN_EH_REGION_BEG and
377 NOTE_INSN_EH_REGION_END notes. */
379 /* Get rid of all NOTE_INSN_PREDICTIONs and NOTE_INSN_LOOP_CONTs
380 hanging before the block. */
382 for (insn = PREV_INSN (BB_HEAD (b)); insn; insn = PREV_INSN (insn))
384 if (GET_CODE (insn) != NOTE)
386 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_PREDICTION
387 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
388 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
393 if (GET_CODE (insn) == CODE_LABEL)
394 maybe_remove_eh_handler (insn);
396 /* Include any jump table following the basic block. */
398 if (tablejump_p (end, NULL, &tmp))
401 /* Include any barrier that may follow the basic block. */
402 tmp = next_nonnote_insn (end);
403 if (tmp && GET_CODE (tmp) == BARRIER)
406 /* Selectively delete the entire chain. */
408 delete_insn_chain (insn, end);
411 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
414 compute_bb_for_insn (void)
420 rtx end = BB_END (bb);
423 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
425 BLOCK_FOR_INSN (insn) = bb;
432 /* Release the basic_block_for_insn array. */
435 free_bb_for_insn (void)
438 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
439 if (GET_CODE (insn) != BARRIER)
440 BLOCK_FOR_INSN (insn) = NULL;
443 /* Update insns block within BB. */
446 update_bb_for_insn (basic_block bb)
450 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
452 if (GET_CODE (insn) != BARRIER)
453 set_block_for_insn (insn, bb);
454 if (insn == BB_END (bb))
459 /* Creates a new basic block just after basic block B by splitting
460 everything after specified instruction I. */
463 rtl_split_block (basic_block bb, void *insnp)
471 insn = first_insn_after_basic_block_note (bb);
474 insn = PREV_INSN (insn);
476 insn = get_last_insn ();
479 /* We probably should check type of the insn so that we do not create
480 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
482 if (insn == BB_END (bb))
483 emit_note_after (NOTE_INSN_DELETED, insn);
485 /* Create the new basic block. */
486 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
489 /* Redirect the outgoing edges. */
490 new_bb->succ = bb->succ;
492 for (e = new_bb->succ; e; e = e->succ_next)
495 if (bb->global_live_at_start)
497 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
498 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
499 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
501 /* We now have to calculate which registers are live at the end
502 of the split basic block and at the start of the new basic
503 block. Start with those registers that are known to be live
504 at the end of the original basic block and get
505 propagate_block to determine which registers are live. */
506 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
507 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
508 COPY_REG_SET (bb->global_live_at_end,
509 new_bb->global_live_at_start);
510 #ifdef HAVE_conditional_execution
511 /* In the presence of conditional execution we are not able to update
512 liveness precisely. */
513 if (reload_completed)
515 bb->flags |= BB_DIRTY;
516 new_bb->flags |= BB_DIRTY;
524 /* Blocks A and B are to be merged into a single block A. The insns
525 are already contiguous. */
528 rtl_merge_blocks (basic_block a, basic_block b)
530 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
531 rtx del_first = NULL_RTX, del_last = NULL_RTX;
534 /* If there was a CODE_LABEL beginning B, delete it. */
535 if (GET_CODE (b_head) == CODE_LABEL)
537 /* Detect basic blocks with nothing but a label. This can happen
538 in particular at the end of a function. */
542 del_first = del_last = b_head;
543 b_head = NEXT_INSN (b_head);
546 /* Delete the basic block note and handle blocks containing just that
548 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
556 b_head = NEXT_INSN (b_head);
559 /* If there was a jump out of A, delete it. */
560 if (GET_CODE (a_end) == JUMP_INSN)
564 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
565 if (GET_CODE (prev) != NOTE
566 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
567 || prev == BB_HEAD (a))
573 /* If this was a conditional jump, we need to also delete
574 the insn that set cc0. */
575 if (only_sets_cc0_p (prev))
579 prev = prev_nonnote_insn (prev);
586 a_end = PREV_INSN (del_first);
588 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
589 del_first = NEXT_INSN (a_end);
591 /* Delete everything marked above as well as crap that might be
592 hanging out between the two blocks. */
594 delete_insn_chain (del_first, del_last);
596 /* Reassociate the insns of B with A. */
601 for (x = a_end; x != b_end; x = NEXT_INSN (x))
602 set_block_for_insn (x, a);
604 set_block_for_insn (b_end, a);
612 /* Return true when block A and B can be merged. */
614 rtl_can_merge_blocks (basic_block a,basic_block b)
616 bool partitions_ok = true;
618 /* If we are partitioning hot/cold basic blocks, we don't want to
619 mess up unconditional or indirect jumps that cross between hot
620 and cold sections. */
622 if (flag_reorder_blocks_and_partition
623 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
624 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
625 || a->partition != b->partition))
626 partitions_ok = false;
628 /* There must be exactly one edge in between the blocks. */
629 return (a->succ && !a->succ->succ_next && a->succ->dest == b
630 && !b->pred->pred_next && a != b
631 /* Must be simple edge. */
632 && !(a->succ->flags & EDGE_COMPLEX)
635 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
636 /* If the jump insn has side effects,
637 we can't kill the edge. */
638 && (GET_CODE (BB_END (a)) != JUMP_INSN
640 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
643 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
647 block_label (basic_block block)
649 if (block == EXIT_BLOCK_PTR)
652 if (GET_CODE (BB_HEAD (block)) != CODE_LABEL)
654 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
657 return BB_HEAD (block);
660 /* Attempt to perform edge redirection by replacing possibly complex jump
661 instruction by unconditional jump or removing jump completely. This can
662 apply only if all edges now point to the same block. The parameters and
663 return values are equivalent to redirect_edge_and_branch. */
666 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
668 basic_block src = e->src;
669 rtx insn = BB_END (src), kill_from;
675 /* If we are partitioning hot/cold basic blocks, we don't want to
676 mess up unconditional or indirect jumps that cross between hot
677 and cold sections. */
679 if (flag_reorder_blocks_and_partition
680 && find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX))
683 /* Verify that all targets will be TARGET. */
684 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
685 if (tmp->dest != target && tmp != e)
688 if (tmp || !onlyjump_p (insn))
690 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
693 /* Avoid removing branch with side effects. */
694 set = single_set (insn);
695 if (!set || side_effects_p (set))
698 /* In case we zap a conditional jump, we'll need to kill
699 the cc0 setter too. */
702 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
703 kill_from = PREV_INSN (insn);
706 /* See if we can create the fallthru edge. */
707 if (in_cfglayout || can_fallthru (src, target))
710 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
713 /* Selectively unlink whole insn chain. */
716 rtx insn = src->rbi->footer;
718 delete_insn_chain (kill_from, BB_END (src));
720 /* Remove barriers but keep jumptables. */
723 if (GET_CODE (insn) == BARRIER)
725 if (PREV_INSN (insn))
726 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
728 src->rbi->footer = NEXT_INSN (insn);
729 if (NEXT_INSN (insn))
730 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
732 if (GET_CODE (insn) == CODE_LABEL)
734 insn = NEXT_INSN (insn);
738 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
741 /* If this already is simplejump, redirect it. */
742 else if (simplejump_p (insn))
744 if (e->dest == target)
747 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
748 INSN_UID (insn), e->dest->index, target->index);
749 if (!redirect_jump (insn, block_label (target), 0))
751 if (target == EXIT_BLOCK_PTR)
757 /* Cannot do anything for target exit block. */
758 else if (target == EXIT_BLOCK_PTR)
761 /* Or replace possibly complicated jump insn by simple jump insn. */
764 rtx target_label = block_label (target);
765 rtx barrier, label, table;
767 emit_jump_insn_after (gen_jump (target_label), insn);
768 JUMP_LABEL (BB_END (src)) = target_label;
769 LABEL_NUSES (target_label)++;
771 fprintf (dump_file, "Replacing insn %i by jump %i\n",
772 INSN_UID (insn), INSN_UID (BB_END (src)));
775 delete_insn_chain (kill_from, insn);
777 /* Recognize a tablejump that we are converting to a
778 simple jump and remove its associated CODE_LABEL
779 and ADDR_VEC or ADDR_DIFF_VEC. */
780 if (tablejump_p (insn, &label, &table))
781 delete_insn_chain (label, table);
783 barrier = next_nonnote_insn (BB_END (src));
784 if (!barrier || GET_CODE (barrier) != BARRIER)
785 emit_barrier_after (BB_END (src));
788 if (barrier != NEXT_INSN (BB_END (src)))
790 /* Move the jump before barrier so that the notes
791 which originally were or were created before jump table are
792 inside the basic block. */
793 rtx new_insn = BB_END (src);
796 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
797 tmp = NEXT_INSN (tmp))
798 set_block_for_insn (tmp, src);
800 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
801 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
803 NEXT_INSN (new_insn) = barrier;
804 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
806 PREV_INSN (new_insn) = PREV_INSN (barrier);
807 PREV_INSN (barrier) = new_insn;
812 /* Keep only one edge out and set proper flags. */
813 while (src->succ->succ_next)
814 remove_edge (src->succ);
817 e->flags = EDGE_FALLTHRU;
821 e->probability = REG_BR_PROB_BASE;
822 e->count = src->count;
824 /* We don't want a block to end on a line-number note since that has
825 the potential of changing the code between -g and not -g. */
826 while (GET_CODE (BB_END (e->src)) == NOTE
827 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
828 delete_insn (BB_END (e->src));
830 if (e->dest != target)
831 redirect_edge_succ (e, target);
836 /* Return last loop_beg note appearing after INSN, before start of next
837 basic block. Return INSN if there are no such notes.
839 When emitting jump to redirect a fallthru edge, it should always appear
840 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
841 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
845 last_loop_beg_note (rtx insn)
849 for (insn = NEXT_INSN (insn); insn && GET_CODE (insn) == NOTE
850 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
851 insn = NEXT_INSN (insn))
852 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
858 /* Redirect edge representing branch of (un)conditional jump or tablejump,
861 redirect_branch_edge (edge e, basic_block target)
864 rtx old_label = BB_HEAD (e->dest);
865 basic_block src = e->src;
866 rtx insn = BB_END (src);
868 /* We can only redirect non-fallthru edges of jump insn. */
869 if (e->flags & EDGE_FALLTHRU)
871 else if (GET_CODE (insn) != JUMP_INSN)
874 /* Recognize a tablejump and adjust all matching cases. */
875 if (tablejump_p (insn, NULL, &tmp))
879 rtx new_label = block_label (target);
881 if (target == EXIT_BLOCK_PTR)
883 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
884 vec = XVEC (PATTERN (tmp), 0);
886 vec = XVEC (PATTERN (tmp), 1);
888 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
889 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
891 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
892 --LABEL_NUSES (old_label);
893 ++LABEL_NUSES (new_label);
896 /* Handle casesi dispatch insns. */
897 if ((tmp = single_set (insn)) != NULL
898 && SET_DEST (tmp) == pc_rtx
899 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
900 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
901 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
903 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
905 --LABEL_NUSES (old_label);
906 ++LABEL_NUSES (new_label);
911 /* ?? We may play the games with moving the named labels from
912 one basic block to the other in case only one computed_jump is
914 if (computed_jump_p (insn)
915 /* A return instruction can't be redirected. */
916 || returnjump_p (insn))
919 /* If the insn doesn't go where we think, we're confused. */
920 if (JUMP_LABEL (insn) != old_label)
923 /* If the substitution doesn't succeed, die. This can happen
924 if the back end emitted unrecognizable instructions or if
925 target is exit block on some arches. */
926 if (!redirect_jump (insn, block_label (target), 0))
928 if (target == EXIT_BLOCK_PTR)
935 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
936 e->src->index, e->dest->index, target->index);
938 if (e->dest != target)
939 e = redirect_edge_succ_nodup (e, target);
943 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
944 expense of adding new instructions or reordering basic blocks.
946 Function can be also called with edge destination equivalent to the TARGET.
947 Then it should try the simplifications and do nothing if none is possible.
949 Return edge representing the branch if transformation succeeded. Return NULL
951 We still return NULL in case E already destinated TARGET and we didn't
952 managed to simplify instruction stream. */
955 rtl_redirect_edge_and_branch (edge e, basic_block target)
958 basic_block src = e->src;
960 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
963 if (e->dest == target)
966 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
968 src->flags |= BB_DIRTY;
972 ret = redirect_branch_edge (e, target);
976 src->flags |= BB_DIRTY;
980 /* Like force_nonfallthru below, but additionally performs redirection
981 Used by redirect_edge_and_branch_force. */
984 force_nonfallthru_and_redirect (edge e, basic_block target)
986 basic_block jump_block, new_bb = NULL, src = e->src;
989 int abnormal_edge_flags = 0;
991 /* In the case the last instruction is conditional jump to the next
992 instruction, first redirect the jump itself and then continue
993 by creating a basic block afterwards to redirect fallthru edge. */
994 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
995 && any_condjump_p (BB_END (e->src))
996 /* When called from cfglayout, fallthru edges do not
997 necessarily go to the next block. */
998 && e->src->next_bb == e->dest
999 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1002 edge b = unchecked_make_edge (e->src, target, 0);
1004 if (!redirect_jump (BB_END (e->src), block_label (target), 0))
1006 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1009 int prob = INTVAL (XEXP (note, 0));
1011 b->probability = prob;
1012 b->count = e->count * prob / REG_BR_PROB_BASE;
1013 e->probability -= e->probability;
1014 e->count -= b->count;
1015 if (e->probability < 0)
1022 if (e->flags & EDGE_ABNORMAL)
1024 /* Irritating special case - fallthru edge to the same block as abnormal
1026 We can't redirect abnormal edge, but we still can split the fallthru
1027 one and create separate abnormal edge to original destination.
1028 This allows bb-reorder to make such edge non-fallthru. */
1029 if (e->dest != target)
1031 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1032 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1034 else if (!(e->flags & EDGE_FALLTHRU))
1036 else if (e->src == ENTRY_BLOCK_PTR)
1038 /* We can't redirect the entry block. Create an empty block at the
1039 start of the function which we use to add the new jump. */
1041 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1043 /* Change the existing edge's source to be the new block, and add
1044 a new edge from the entry block to the new block. */
1046 for (pe1 = &ENTRY_BLOCK_PTR->succ; *pe1; pe1 = &(*pe1)->succ_next)
1049 *pe1 = e->succ_next;
1054 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1057 if (e->src->succ->succ_next || abnormal_edge_flags)
1059 /* Create the new structures. */
1061 /* If the old block ended with a tablejump, skip its table
1062 by searching forward from there. Otherwise start searching
1063 forward from the last instruction of the old block. */
1064 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1065 note = BB_END (e->src);
1067 /* Position the new block correctly relative to loop notes. */
1068 note = last_loop_beg_note (note);
1069 note = NEXT_INSN (note);
1071 jump_block = create_basic_block (note, NULL, e->src);
1072 jump_block->count = e->count;
1073 jump_block->frequency = EDGE_FREQUENCY (e);
1074 jump_block->loop_depth = target->loop_depth;
1076 if (target->global_live_at_start)
1078 jump_block->global_live_at_start
1079 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1080 jump_block->global_live_at_end
1081 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1082 COPY_REG_SET (jump_block->global_live_at_start,
1083 target->global_live_at_start);
1084 COPY_REG_SET (jump_block->global_live_at_end,
1085 target->global_live_at_start);
1088 /* Make sure new block ends up in correct hot/cold section. */
1090 jump_block->partition = e->src->partition;
1091 if (flag_reorder_blocks_and_partition)
1093 if (e->src->partition == COLD_PARTITION)
1095 rtx bb_note, new_note;
1096 for (bb_note = BB_HEAD (jump_block);
1097 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1098 bb_note = NEXT_INSN (bb_note))
1099 if (GET_CODE (bb_note) == NOTE
1100 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1102 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1104 NOTE_BASIC_BLOCK (new_note) = jump_block;
1105 jump_block->partition = COLD_PARTITION;
1107 if (GET_CODE (BB_END (jump_block)) == JUMP_INSN
1108 && !any_condjump_p (BB_END (jump_block))
1109 && jump_block->succ->crossing_edge )
1110 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1111 (REG_CROSSING_JUMP, NULL_RTX,
1112 REG_NOTES (BB_END (jump_block)));
1116 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1117 new_edge->probability = e->probability;
1118 new_edge->count = e->count;
1120 /* Redirect old edge. */
1121 redirect_edge_pred (e, jump_block);
1122 e->probability = REG_BR_PROB_BASE;
1124 new_bb = jump_block;
1127 jump_block = e->src;
1129 e->flags &= ~EDGE_FALLTHRU;
1130 if (target == EXIT_BLOCK_PTR)
1133 emit_jump_insn_after (gen_return (), BB_END (jump_block));
1140 rtx label = block_label (target);
1141 emit_jump_insn_after (gen_jump (label), BB_END (jump_block));
1142 JUMP_LABEL (BB_END (jump_block)) = label;
1143 LABEL_NUSES (label)++;
1146 emit_barrier_after (BB_END (jump_block));
1147 redirect_edge_succ_nodup (e, target);
1149 if (abnormal_edge_flags)
1150 make_edge (src, target, abnormal_edge_flags);
1155 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1156 (and possibly create new basic block) to make edge non-fallthru.
1157 Return newly created BB or NULL if none. */
1160 force_nonfallthru (edge e)
1162 return force_nonfallthru_and_redirect (e, e->dest);
1165 /* Redirect edge even at the expense of creating new jump insn or
1166 basic block. Return new basic block if created, NULL otherwise.
1167 Abort if conversion is impossible. */
1170 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1172 if (redirect_edge_and_branch (e, target)
1173 || e->dest == target)
1176 /* In case the edge redirection failed, try to force it to be non-fallthru
1177 and redirect newly created simplejump. */
1178 return force_nonfallthru_and_redirect (e, target);
1181 /* The given edge should potentially be a fallthru edge. If that is in
1182 fact true, delete the jump and barriers that are in the way. */
1185 rtl_tidy_fallthru_edge (edge e)
1188 basic_block b = e->src, c = b->next_bb;
1190 /* ??? In a late-running flow pass, other folks may have deleted basic
1191 blocks by nopping out blocks, leaving multiple BARRIERs between here
1192 and the target label. They ought to be chastized and fixed.
1194 We can also wind up with a sequence of undeletable labels between
1195 one block and the next.
1197 So search through a sequence of barriers, labels, and notes for
1198 the head of block C and assert that we really do fall through. */
1200 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1204 /* Remove what will soon cease being the jump insn from the source block.
1205 If block B consisted only of this single jump, turn it into a deleted
1208 if (GET_CODE (q) == JUMP_INSN
1210 && (any_uncondjump_p (q)
1211 || (b->succ == e && e->succ_next == NULL)))
1214 /* If this was a conditional jump, we need to also delete
1215 the insn that set cc0. */
1216 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1222 /* We don't want a block to end on a line-number note since that has
1223 the potential of changing the code between -g and not -g. */
1224 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
1228 /* Selectively unlink the sequence. */
1229 if (q != PREV_INSN (BB_HEAD (c)))
1230 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1232 e->flags |= EDGE_FALLTHRU;
1235 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1236 is back edge of syntactic loop. */
1239 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1248 /* ??? Could we guarantee that bb indices are monotone, so that we could
1249 just compare them? */
1250 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1256 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1257 insn = NEXT_INSN (insn))
1258 if (GET_CODE (insn) == NOTE)
1260 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1262 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1269 /* Should move basic block BB after basic block AFTER. NIY. */
1272 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1273 basic_block after ATTRIBUTE_UNUSED)
1278 /* Split a (typically critical) edge. Return the new block.
1279 Abort on abnormal edges.
1281 ??? The code generally expects to be called on critical edges.
1282 The case of a block ending in an unconditional jump to a
1283 block with multiple predecessors is not handled optimally. */
1286 rtl_split_edge (edge edge_in)
1291 /* Abnormal edges cannot be split. */
1292 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1295 /* We are going to place the new block in front of edge destination.
1296 Avoid existence of fallthru predecessors. */
1297 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1301 for (e = edge_in->dest->pred; e; e = e->pred_next)
1302 if (e->flags & EDGE_FALLTHRU)
1306 force_nonfallthru (e);
1309 /* Create the basic block note.
1311 Where we place the note can have a noticeable impact on the generated
1312 code. Consider this cfg:
1322 If we need to insert an insn on the edge from block 0 to block 1,
1323 we want to ensure the instructions we insert are outside of any
1324 loop notes that physically sit between block 0 and block 1. Otherwise
1325 we confuse the loop optimizer into thinking the loop is a phony. */
1327 if (edge_in->dest != EXIT_BLOCK_PTR
1328 && PREV_INSN (BB_HEAD (edge_in->dest))
1329 && GET_CODE (PREV_INSN (BB_HEAD (edge_in->dest))) == NOTE
1330 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1331 == NOTE_INSN_LOOP_BEG)
1332 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1333 before = PREV_INSN (BB_HEAD (edge_in->dest));
1334 else if (edge_in->dest != EXIT_BLOCK_PTR)
1335 before = BB_HEAD (edge_in->dest);
1339 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1341 /* ??? This info is likely going to be out of date very soon. */
1342 if (edge_in->dest->global_live_at_start)
1344 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1345 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1346 COPY_REG_SET (bb->global_live_at_start,
1347 edge_in->dest->global_live_at_start);
1348 COPY_REG_SET (bb->global_live_at_end,
1349 edge_in->dest->global_live_at_start);
1352 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1354 /* For non-fallthru edges, we must adjust the predecessor's
1355 jump instruction to target our new block. */
1356 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1358 if (!redirect_edge_and_branch (edge_in, bb))
1362 redirect_edge_succ (edge_in, bb);
1367 /* Queue instructions for insertion on an edge between two basic blocks.
1368 The new instructions and basic blocks (if any) will not appear in the
1369 CFG until commit_edge_insertions is called. */
1372 insert_insn_on_edge (rtx pattern, edge e)
1374 /* We cannot insert instructions on an abnormal critical edge.
1375 It will be easier to find the culprit if we die now. */
1376 if ((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))
1379 if (e->insns.r == NULL_RTX)
1382 push_to_sequence (e->insns.r);
1384 emit_insn (pattern);
1386 e->insns.r = get_insns ();
1390 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1391 registers that are killed by the store. */
1393 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1395 regset killed = data;
1398 if (GET_CODE (reg) == SUBREG)
1399 reg = SUBREG_REG (reg);
1402 regno = REGNO (reg);
1403 if (regno >= FIRST_PSEUDO_REGISTER)
1404 SET_REGNO_REG_SET (killed, regno);
1407 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1408 SET_REGNO_REG_SET (killed, regno + i);
1412 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1413 it checks whether this will not clobber the registers that are live on the
1414 edge (i.e. it requires liveness information to be up-to-date) and if there
1415 are some, then it tries to save and restore them. Returns true if
1418 safe_insert_insn_on_edge (rtx insn, edge e)
1421 regset_head killed_head;
1422 regset killed = INITIALIZE_REG_SET (killed_head);
1423 rtx save_regs = NULL_RTX;
1424 int regno, noccmode;
1425 enum machine_mode mode;
1427 #ifdef AVOID_CCMODE_COPIES
1433 for (x = insn; x; x = NEXT_INSN (x))
1435 note_stores (PATTERN (x), mark_killed_regs, killed);
1436 bitmap_operation (killed, killed, e->dest->global_live_at_start,
1439 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno,
1441 mode = regno < FIRST_PSEUDO_REGISTER
1442 ? reg_raw_mode[regno]
1443 : GET_MODE (regno_reg_rtx[regno]);
1444 if (mode == VOIDmode)
1447 if (noccmode && mode == CCmode)
1450 save_regs = alloc_EXPR_LIST (0,
1453 gen_raw_REG (mode, regno)),
1462 for (x = save_regs; x; x = XEXP (x, 1))
1464 from = XEXP (XEXP (x, 0), 1);
1465 to = XEXP (XEXP (x, 0), 0);
1466 emit_move_insn (to, from);
1469 for (x = save_regs; x; x = XEXP (x, 1))
1471 from = XEXP (XEXP (x, 0), 0);
1472 to = XEXP (XEXP (x, 0), 1);
1473 emit_move_insn (to, from);
1475 insn = get_insns ();
1477 free_EXPR_LIST_list (&save_regs);
1479 insert_insn_on_edge (insn, e);
1481 FREE_REG_SET (killed);
1485 /* Update the CFG for the instructions queued on edge E. */
1488 commit_one_edge_insertion (edge e, int watch_calls)
1490 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1491 basic_block bb = NULL;
1493 /* Pull the insns off the edge now since the edge might go away. */
1495 e->insns.r = NULL_RTX;
1497 /* Special case -- avoid inserting code between call and storing
1498 its return value. */
1499 if (watch_calls && (e->flags & EDGE_FALLTHRU) && !e->dest->pred->pred_next
1500 && e->src != ENTRY_BLOCK_PTR
1501 && GET_CODE (BB_END (e->src)) == CALL_INSN)
1503 rtx next = next_nonnote_insn (BB_END (e->src));
1505 after = BB_HEAD (e->dest);
1506 /* The first insn after the call may be a stack pop, skip it. */
1508 && keep_with_call_p (next))
1511 next = next_nonnote_insn (next);
1515 if (!before && !after)
1517 /* Figure out where to put these things. If the destination has
1518 one predecessor, insert there. Except for the exit block. */
1519 if (e->dest->pred->pred_next == NULL && e->dest != EXIT_BLOCK_PTR)
1523 /* Get the location correct wrt a code label, and "nice" wrt
1524 a basic block note, and before everything else. */
1526 if (GET_CODE (tmp) == CODE_LABEL)
1527 tmp = NEXT_INSN (tmp);
1528 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1529 tmp = NEXT_INSN (tmp);
1531 && GET_CODE (tmp) == NOTE
1532 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1533 tmp = NEXT_INSN (tmp);
1534 if (tmp == BB_HEAD (bb))
1537 after = PREV_INSN (tmp);
1539 after = get_last_insn ();
1542 /* If the source has one successor and the edge is not abnormal,
1543 insert there. Except for the entry block. */
1544 else if ((e->flags & EDGE_ABNORMAL) == 0
1545 && e->src->succ->succ_next == NULL
1546 && e->src != ENTRY_BLOCK_PTR)
1550 /* It is possible to have a non-simple jump here. Consider a target
1551 where some forms of unconditional jumps clobber a register. This
1552 happens on the fr30 for example.
1554 We know this block has a single successor, so we can just emit
1555 the queued insns before the jump. */
1556 if (GET_CODE (BB_END (bb)) == JUMP_INSN)
1557 for (before = BB_END (bb);
1558 GET_CODE (PREV_INSN (before)) == NOTE
1559 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1560 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1564 /* We'd better be fallthru, or we've lost track of what's what. */
1565 if ((e->flags & EDGE_FALLTHRU) == 0)
1568 after = BB_END (bb);
1571 /* Otherwise we must split the edge. */
1574 bb = split_edge (e);
1575 after = BB_END (bb);
1577 /* If we are partitioning hot/cold basic blocks, we must make sure
1578 that the new basic block ends up in the correct section. */
1580 bb->partition = e->src->partition;
1581 if (flag_reorder_blocks_and_partition
1582 && e->src != ENTRY_BLOCK_PTR
1583 && e->src->partition == COLD_PARTITION)
1585 rtx bb_note, new_note, cur_insn;
1588 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1589 cur_insn = NEXT_INSN (cur_insn))
1590 if (GET_CODE (cur_insn) == NOTE
1591 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1597 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1599 NOTE_BASIC_BLOCK (new_note) = bb;
1600 if (GET_CODE (BB_END (bb)) == JUMP_INSN
1601 && !any_condjump_p (BB_END (bb))
1602 && bb->succ->crossing_edge )
1603 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1604 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1605 if (after == bb_note)
1611 /* Now that we've found the spot, do the insertion. */
1615 emit_insn_before (insns, before);
1616 last = prev_nonnote_insn (before);
1619 last = emit_insn_after (insns, after);
1621 if (returnjump_p (last))
1623 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1624 This is not currently a problem because this only happens
1625 for the (single) epilogue, which already has a fallthru edge
1629 if (e->dest != EXIT_BLOCK_PTR
1630 || e->succ_next != NULL || (e->flags & EDGE_FALLTHRU) == 0)
1633 e->flags &= ~EDGE_FALLTHRU;
1634 emit_barrier_after (last);
1637 delete_insn (before);
1639 else if (GET_CODE (last) == JUMP_INSN)
1642 /* Mark the basic block for find_sub_basic_blocks. */
1646 /* Update the CFG for all queued instructions. */
1649 commit_edge_insertions (void)
1653 bool changed = false;
1655 #ifdef ENABLE_CHECKING
1656 verify_flow_info ();
1659 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1663 for (e = bb->succ; e; e = next)
1665 next = e->succ_next;
1669 commit_one_edge_insertion (e, false);
1677 blocks = sbitmap_alloc (last_basic_block);
1678 sbitmap_zero (blocks);
1682 SET_BIT (blocks, bb->index);
1683 /* Check for forgotten bb->aux values before commit_edge_insertions
1685 if (bb->aux != &bb->aux)
1689 find_many_sub_basic_blocks (blocks);
1690 sbitmap_free (blocks);
1693 /* Update the CFG for all queued instructions, taking special care of inserting
1694 code on edges between call and storing its return value. */
1697 commit_edge_insertions_watch_calls (void)
1701 bool changed = false;
1703 #ifdef ENABLE_CHECKING
1704 verify_flow_info ();
1707 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1711 for (e = bb->succ; e; e = next)
1713 next = e->succ_next;
1717 commit_one_edge_insertion (e, true);
1725 blocks = sbitmap_alloc (last_basic_block);
1726 sbitmap_zero (blocks);
1730 SET_BIT (blocks, bb->index);
1731 /* Check for forgotten bb->aux values before commit_edge_insertions
1733 if (bb->aux != &bb->aux)
1737 find_many_sub_basic_blocks (blocks);
1738 sbitmap_free (blocks);
1741 /* Print out RTL-specific basic block information (live information
1742 at start and end). */
1745 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1751 s_indent = alloca ((size_t) indent + 1);
1752 memset (s_indent, ' ', (size_t) indent);
1753 s_indent[indent] = '\0';
1755 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1756 dump_regset (bb->global_live_at_start, outf);
1759 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1760 insn = NEXT_INSN (insn))
1761 print_rtl_single (outf, insn);
1763 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1764 dump_regset (bb->global_live_at_end, outf);
1768 /* Like print_rtl, but also print out live information for the start of each
1772 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1777 fprintf (outf, "(nil)\n");
1780 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1781 int max_uid = get_max_uid ();
1782 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1783 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1784 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1788 FOR_EACH_BB_REVERSE (bb)
1792 start[INSN_UID (BB_HEAD (bb))] = bb;
1793 end[INSN_UID (BB_END (bb))] = bb;
1794 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1796 enum bb_state state = IN_MULTIPLE_BB;
1798 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1800 in_bb_p[INSN_UID (x)] = state;
1802 if (x == BB_END (bb))
1807 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1811 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1813 fprintf (outf, ";; Start of basic block %d, registers live:",
1815 dump_regset (bb->global_live_at_start, outf);
1819 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1820 && GET_CODE (tmp_rtx) != NOTE
1821 && GET_CODE (tmp_rtx) != BARRIER)
1822 fprintf (outf, ";; Insn is not within a basic block\n");
1823 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1824 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1826 did_output = print_rtl_single (outf, tmp_rtx);
1828 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1830 fprintf (outf, ";; End of basic block %d, registers live:\n",
1832 dump_regset (bb->global_live_at_end, outf);
1845 if (current_function_epilogue_delay_list != 0)
1847 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1848 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1849 tmp_rtx = XEXP (tmp_rtx, 1))
1850 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1855 update_br_prob_note (basic_block bb)
1858 if (GET_CODE (BB_END (bb)) != JUMP_INSN)
1860 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1861 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1863 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1866 /* Verify the CFG and RTL consistency common for both underlying RTL and
1869 Currently it does following checks:
1871 - test head/end pointers
1872 - overlapping of basic blocks
1873 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1874 - tails of basic blocks (ensure that boundary is necessary)
1875 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1876 and NOTE_INSN_BASIC_BLOCK
1877 - verify that no fall_thru edge crosses hot/cold partition boundaries
1879 In future it can be extended check a lot of other stuff as well
1880 (reachability of basic blocks, life information, etc. etc.). */
1883 rtl_verify_flow_info_1 (void)
1885 const int max_uid = get_max_uid ();
1886 rtx last_head = get_last_insn ();
1887 basic_block *bb_info;
1890 basic_block bb, last_bb_seen;
1892 bb_info = xcalloc (max_uid, sizeof (basic_block));
1894 /* Check bb chain & numbers. */
1895 last_bb_seen = ENTRY_BLOCK_PTR;
1897 FOR_EACH_BB_REVERSE (bb)
1899 rtx head = BB_HEAD (bb);
1900 rtx end = BB_END (bb);
1902 /* Verify the end of the basic block is in the INSN chain. */
1903 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1909 error ("end insn %d for block %d not found in the insn stream",
1910 INSN_UID (end), bb->index);
1914 /* Work backwards from the end to the head of the basic block
1915 to verify the head is in the RTL chain. */
1916 for (; x != NULL_RTX; x = PREV_INSN (x))
1918 /* While walking over the insn chain, verify insns appear
1919 in only one basic block and initialize the BB_INFO array
1920 used by other passes. */
1921 if (bb_info[INSN_UID (x)] != NULL)
1923 error ("insn %d is in multiple basic blocks (%d and %d)",
1924 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1928 bb_info[INSN_UID (x)] = bb;
1935 error ("head insn %d for block %d not found in the insn stream",
1936 INSN_UID (head), bb->index);
1943 /* Now check the basic blocks (boundaries etc.) */
1944 FOR_EACH_BB_REVERSE (bb)
1946 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1947 edge e, fallthru = NULL;
1950 if (INSN_P (BB_END (bb))
1951 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1952 && bb->succ && bb->succ->succ_next
1953 && any_condjump_p (BB_END (bb)))
1955 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability)
1957 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1958 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1962 for (e = bb->succ; e; e = e->succ_next)
1964 if (e->flags & EDGE_FALLTHRU)
1966 n_fallthru++, fallthru = e;
1967 if (e->crossing_edge)
1969 error ("Fallthru edge crosses section boundary (bb %i)",
1975 if ((e->flags & ~(EDGE_DFS_BACK
1977 | EDGE_IRREDUCIBLE_LOOP
1978 | EDGE_LOOP_EXIT)) == 0)
1981 if (e->flags & EDGE_ABNORMAL_CALL)
1984 if (e->flags & EDGE_EH)
1986 else if (e->flags & EDGE_ABNORMAL)
1990 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
1991 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1993 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
1997 && (GET_CODE (BB_END (bb)) != JUMP_INSN
1998 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1999 || any_condjump_p (BB_END (bb))))))
2001 error ("Too many outgoing branch edges from bb %i", bb->index);
2004 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2006 error ("Fallthru edge after unconditional jump %i", bb->index);
2009 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2011 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2014 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2015 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2017 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2020 if (n_call && GET_CODE (BB_END (bb)) != CALL_INSN)
2022 error ("Call edges for non-call insn in bb %i", bb->index);
2026 && (GET_CODE (BB_END (bb)) != CALL_INSN && n_call != n_abnormal)
2027 && (GET_CODE (BB_END (bb)) != JUMP_INSN
2028 || any_condjump_p (BB_END (bb))
2029 || any_uncondjump_p (BB_END (bb))))
2031 error ("Abnormal edges for no purpose in bb %i", bb->index);
2035 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2036 if (BLOCK_FOR_INSN (x) != bb)
2039 if (! BLOCK_FOR_INSN (x))
2041 ("insn %d inside basic block %d but block_for_insn is NULL",
2042 INSN_UID (x), bb->index);
2045 ("insn %d inside basic block %d but block_for_insn is %i",
2046 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2051 /* OK pointers are correct. Now check the header of basic
2052 block. It ought to contain optional CODE_LABEL followed
2053 by NOTE_BASIC_BLOCK. */
2055 if (GET_CODE (x) == CODE_LABEL)
2057 if (BB_END (bb) == x)
2059 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2067 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2069 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2074 if (BB_END (bb) == x)
2075 /* Do checks for empty blocks her. e */
2078 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2080 if (NOTE_INSN_BASIC_BLOCK_P (x))
2082 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2083 INSN_UID (x), bb->index);
2087 if (x == BB_END (bb))
2090 if (control_flow_insn_p (x))
2092 error ("in basic block %d:", bb->index);
2093 fatal_insn ("flow control insn inside a basic block", x);
2103 /* Verify the CFG and RTL consistency common for both underlying RTL and
2106 Currently it does following checks:
2107 - all checks of rtl_verify_flow_info_1
2108 - check that all insns are in the basic blocks
2109 (except the switch handling code, barriers and notes)
2110 - check that all returns are followed by barriers
2111 - check that all fallthru edge points to the adjacent blocks. */
2113 rtl_verify_flow_info (void)
2116 int err = rtl_verify_flow_info_1 ();
2119 const rtx rtx_first = get_insns ();
2120 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2122 FOR_EACH_BB_REVERSE (bb)
2125 for (e = bb->succ; e; e = e->succ_next)
2126 if (e->flags & EDGE_FALLTHRU)
2132 /* Ensure existence of barrier in BB with no fallthru edges. */
2133 for (insn = BB_END (bb); !insn || GET_CODE (insn) != BARRIER;
2134 insn = NEXT_INSN (insn))
2136 || (GET_CODE (insn) == NOTE
2137 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2139 error ("missing barrier after block %i", bb->index);
2144 else if (e->src != ENTRY_BLOCK_PTR
2145 && e->dest != EXIT_BLOCK_PTR)
2149 if (e->src->next_bb != e->dest)
2152 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2153 e->src->index, e->dest->index);
2157 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2158 insn = NEXT_INSN (insn))
2159 if (GET_CODE (insn) == BARRIER
2160 #ifndef CASE_DROPS_THROUGH
2163 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2167 error ("verify_flow_info: Incorrect fallthru %i->%i",
2168 e->src->index, e->dest->index);
2169 fatal_insn ("wrong insn in the fallthru edge", insn);
2176 last_bb_seen = ENTRY_BLOCK_PTR;
2178 for (x = rtx_first; x; x = NEXT_INSN (x))
2180 if (NOTE_INSN_BASIC_BLOCK_P (x))
2182 bb = NOTE_BASIC_BLOCK (x);
2185 if (bb != last_bb_seen->next_bb)
2186 internal_error ("basic blocks not laid down consecutively");
2188 curr_bb = last_bb_seen = bb;
2193 switch (GET_CODE (x))
2200 /* An addr_vec is placed outside any basic block. */
2202 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
2203 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2204 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2207 /* But in any case, non-deletable labels can appear anywhere. */
2211 fatal_insn ("insn outside basic block", x);
2216 && GET_CODE (x) == JUMP_INSN
2217 && returnjump_p (x) && ! condjump_p (x)
2218 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
2219 fatal_insn ("return not followed by barrier", x);
2220 if (curr_bb && x == BB_END (curr_bb))
2224 if (num_bb_notes != n_basic_blocks)
2226 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2227 num_bb_notes, n_basic_blocks);
2232 /* Assume that the preceding pass has possibly eliminated jump instructions
2233 or converted the unconditional jumps. Eliminate the edges from CFG.
2234 Return true if any edges are eliminated. */
2237 purge_dead_edges (basic_block bb)
2240 rtx insn = BB_END (bb), note;
2241 bool purged = false;
2243 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2244 if (GET_CODE (insn) == INSN
2245 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2249 if (! may_trap_p (PATTERN (insn))
2250 || ((eqnote = find_reg_equal_equiv_note (insn))
2251 && ! may_trap_p (XEXP (eqnote, 0))))
2252 remove_note (insn, note);
2255 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2256 for (e = bb->succ; e; e = next)
2258 next = e->succ_next;
2259 if (e->flags & EDGE_EH)
2261 if (can_throw_internal (BB_END (bb)))
2264 else if (e->flags & EDGE_ABNORMAL_CALL)
2266 if (GET_CODE (BB_END (bb)) == CALL_INSN
2267 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2268 || INTVAL (XEXP (note, 0)) >= 0))
2275 bb->flags |= BB_DIRTY;
2279 if (GET_CODE (insn) == JUMP_INSN)
2284 /* We do care only about conditional jumps and simplejumps. */
2285 if (!any_condjump_p (insn)
2286 && !returnjump_p (insn)
2287 && !simplejump_p (insn))
2290 /* Branch probability/prediction notes are defined only for
2291 condjumps. We've possibly turned condjump into simplejump. */
2292 if (simplejump_p (insn))
2294 note = find_reg_note (insn, REG_BR_PROB, NULL);
2296 remove_note (insn, note);
2297 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2298 remove_note (insn, note);
2301 for (e = bb->succ; e; e = next)
2303 next = e->succ_next;
2305 /* Avoid abnormal flags to leak from computed jumps turned
2306 into simplejumps. */
2308 e->flags &= ~EDGE_ABNORMAL;
2310 /* See if this edge is one we should keep. */
2311 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2312 /* A conditional jump can fall through into the next
2313 block, so we should keep the edge. */
2315 else if (e->dest != EXIT_BLOCK_PTR
2316 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2317 /* If the destination block is the target of the jump,
2320 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2321 /* If the destination block is the exit block, and this
2322 instruction is a return, then keep the edge. */
2324 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2325 /* Keep the edges that correspond to exceptions thrown by
2326 this instruction and rematerialize the EDGE_ABNORMAL
2327 flag we just cleared above. */
2329 e->flags |= EDGE_ABNORMAL;
2333 /* We do not need this edge. */
2334 bb->flags |= BB_DIRTY;
2339 if (!bb->succ || !purged)
2343 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2348 /* Redistribute probabilities. */
2349 if (!bb->succ->succ_next)
2351 bb->succ->probability = REG_BR_PROB_BASE;
2352 bb->succ->count = bb->count;
2356 note = find_reg_note (insn, REG_BR_PROB, NULL);
2360 b = BRANCH_EDGE (bb);
2361 f = FALLTHRU_EDGE (bb);
2362 b->probability = INTVAL (XEXP (note, 0));
2363 f->probability = REG_BR_PROB_BASE - b->probability;
2364 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2365 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2370 else if (GET_CODE (insn) == CALL_INSN && SIBLING_CALL_P (insn))
2372 /* First, there should not be any EH or ABCALL edges resulting
2373 from non-local gotos and the like. If there were, we shouldn't
2374 have created the sibcall in the first place. Second, there
2375 should of course never have been a fallthru edge. */
2376 if (!bb->succ || bb->succ->succ_next)
2378 if (bb->succ->flags != (EDGE_SIBCALL | EDGE_ABNORMAL))
2384 /* If we don't see a jump insn, we don't know exactly why the block would
2385 have been broken at this point. Look for a simple, non-fallthru edge,
2386 as these are only created by conditional branches. If we find such an
2387 edge we know that there used to be a jump here and can then safely
2388 remove all non-fallthru edges. */
2389 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
2396 for (e = bb->succ; e; e = next)
2398 next = e->succ_next;
2399 if (!(e->flags & EDGE_FALLTHRU))
2401 bb->flags |= BB_DIRTY;
2407 if (!bb->succ || bb->succ->succ_next)
2410 bb->succ->probability = REG_BR_PROB_BASE;
2411 bb->succ->count = bb->count;
2414 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2419 /* Search all basic blocks for potentially dead edges and purge them. Return
2420 true if some edge has been eliminated. */
2423 purge_all_dead_edges (int update_life_p)
2431 blocks = sbitmap_alloc (last_basic_block);
2432 sbitmap_zero (blocks);
2437 bool purged_here = purge_dead_edges (bb);
2439 purged |= purged_here;
2440 if (purged_here && update_life_p)
2441 SET_BIT (blocks, bb->index);
2444 if (update_life_p && purged)
2445 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2446 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2447 | PROP_KILL_DEAD_CODE);
2450 sbitmap_free (blocks);
2454 /* Same as split_block but update cfg_layout structures. */
2457 cfg_layout_split_block (basic_block bb, void *insnp)
2460 basic_block new_bb = rtl_split_block (bb, insn);
2462 new_bb->rbi->footer = bb->rbi->footer;
2463 bb->rbi->footer = NULL;
2469 /* Redirect Edge to DEST. */
2471 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2473 basic_block src = e->src;
2476 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2479 if (e->dest == dest)
2482 if (e->src != ENTRY_BLOCK_PTR
2483 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2485 src->flags |= BB_DIRTY;
2489 if (e->src == ENTRY_BLOCK_PTR
2490 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2493 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2494 e->src->index, dest->index);
2496 e->src->flags |= BB_DIRTY;
2497 redirect_edge_succ (e, dest);
2501 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2502 in the case the basic block appears to be in sequence. Avoid this
2505 if (e->flags & EDGE_FALLTHRU)
2507 /* Redirect any branch edges unified with the fallthru one. */
2508 if (GET_CODE (BB_END (src)) == JUMP_INSN
2509 && label_is_jump_target_p (BB_HEAD (e->dest),
2513 fprintf (dump_file, "Fallthru edge unified with branch "
2514 "%i->%i redirected to %i\n",
2515 e->src->index, e->dest->index, dest->index);
2516 e->flags &= ~EDGE_FALLTHRU;
2517 if (!redirect_branch_edge (e, dest))
2519 e->flags |= EDGE_FALLTHRU;
2520 e->src->flags |= BB_DIRTY;
2523 /* In case we are redirecting fallthru edge to the branch edge
2524 of conditional jump, remove it. */
2525 if (src->succ->succ_next
2526 && !src->succ->succ_next->succ_next)
2528 edge s = e->succ_next ? e->succ_next : src->succ;
2530 && any_condjump_p (BB_END (src))
2531 && onlyjump_p (BB_END (src)))
2532 delete_insn (BB_END (src));
2534 ret = redirect_edge_succ_nodup (e, dest);
2536 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2537 e->src->index, e->dest->index, dest->index);
2540 ret = redirect_branch_edge (e, dest);
2542 /* We don't want simplejumps in the insn stream during cfglayout. */
2543 if (simplejump_p (BB_END (src)))
2546 src->flags |= BB_DIRTY;
2550 /* Simple wrapper as we always can redirect fallthru edges. */
2552 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2554 if (!cfg_layout_redirect_edge_and_branch (e, dest))
2559 /* Same as delete_basic_block but update cfg_layout structures. */
2562 cfg_layout_delete_block (basic_block bb)
2564 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2566 if (bb->rbi->header)
2568 next = BB_HEAD (bb);
2570 NEXT_INSN (prev) = bb->rbi->header;
2572 set_first_insn (bb->rbi->header);
2573 PREV_INSN (bb->rbi->header) = prev;
2574 insn = bb->rbi->header;
2575 while (NEXT_INSN (insn))
2576 insn = NEXT_INSN (insn);
2577 NEXT_INSN (insn) = next;
2578 PREV_INSN (next) = insn;
2580 next = NEXT_INSN (BB_END (bb));
2581 if (bb->rbi->footer)
2583 insn = bb->rbi->footer;
2586 if (GET_CODE (insn) == BARRIER)
2588 if (PREV_INSN (insn))
2589 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2591 bb->rbi->footer = NEXT_INSN (insn);
2592 if (NEXT_INSN (insn))
2593 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2595 if (GET_CODE (insn) == CODE_LABEL)
2597 insn = NEXT_INSN (insn);
2599 if (bb->rbi->footer)
2602 NEXT_INSN (insn) = bb->rbi->footer;
2603 PREV_INSN (bb->rbi->footer) = insn;
2604 while (NEXT_INSN (insn))
2605 insn = NEXT_INSN (insn);
2606 NEXT_INSN (insn) = next;
2608 PREV_INSN (next) = insn;
2610 set_last_insn (insn);
2613 if (bb->next_bb != EXIT_BLOCK_PTR)
2614 to = &bb->next_bb->rbi->header;
2616 to = &cfg_layout_function_footer;
2617 rtl_delete_block (bb);
2620 prev = NEXT_INSN (prev);
2622 prev = get_insns ();
2624 next = PREV_INSN (next);
2626 next = get_last_insn ();
2628 if (next && NEXT_INSN (next) != prev)
2630 remaints = unlink_insn_chain (prev, next);
2632 while (NEXT_INSN (insn))
2633 insn = NEXT_INSN (insn);
2634 NEXT_INSN (insn) = *to;
2636 PREV_INSN (*to) = insn;
2641 /* Return true when blocks A and B can be safely merged. */
2643 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2645 bool partitions_ok = true;
2647 /* If we are partitioning hot/cold basic blocks, we don't want to
2648 mess up unconditional or indirect jumps that cross between hot
2649 and cold sections. */
2651 if (flag_reorder_blocks_and_partition
2652 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2653 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2654 || a->partition != b->partition))
2655 partitions_ok = false;
2657 /* There must be exactly one edge in between the blocks. */
2658 return (a->succ && !a->succ->succ_next && a->succ->dest == b
2659 && !b->pred->pred_next && a != b
2660 /* Must be simple edge. */
2661 && !(a->succ->flags & EDGE_COMPLEX)
2663 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2664 /* If the jump insn has side effects,
2665 we can't kill the edge. */
2666 && (GET_CODE (BB_END (a)) != JUMP_INSN
2667 || (reload_completed
2668 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2671 /* Merge block A and B, abort when it is not possible. */
2673 cfg_layout_merge_blocks (basic_block a, basic_block b)
2675 #ifdef ENABLE_CHECKING
2676 if (!cfg_layout_can_merge_blocks_p (a, b))
2680 /* If there was a CODE_LABEL beginning B, delete it. */
2681 if (GET_CODE (BB_HEAD (b)) == CODE_LABEL)
2682 delete_insn (BB_HEAD (b));
2684 /* We should have fallthru edge in a, or we can do dummy redirection to get
2686 if (GET_CODE (BB_END (a)) == JUMP_INSN)
2687 try_redirect_by_replacing_jump (a->succ, b, true);
2688 if (GET_CODE (BB_END (a)) == JUMP_INSN)
2691 /* Possible line number notes should appear in between. */
2694 rtx first = BB_END (a), last;
2696 last = emit_insn_after (b->rbi->header, BB_END (a));
2697 delete_insn_chain (NEXT_INSN (first), last);
2698 b->rbi->header = NULL;
2701 /* In the case basic blocks are not adjacent, move them around. */
2702 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2704 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2706 emit_insn_after (first, BB_END (a));
2707 /* Skip possible DELETED_LABEL insn. */
2708 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2709 first = NEXT_INSN (first);
2710 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2713 delete_insn (first);
2715 /* Otherwise just re-associate the instructions. */
2720 for (insn = BB_HEAD (b);
2721 insn != NEXT_INSN (BB_END (b));
2722 insn = NEXT_INSN (insn))
2723 set_block_for_insn (insn, a);
2725 /* Skip possible DELETED_LABEL insn. */
2726 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2727 insn = NEXT_INSN (insn);
2728 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2731 BB_END (a) = BB_END (b);
2735 /* Possible tablejumps and barriers should appear after the block. */
2738 if (!a->rbi->footer)
2739 a->rbi->footer = b->rbi->footer;
2742 rtx last = a->rbi->footer;
2744 while (NEXT_INSN (last))
2745 last = NEXT_INSN (last);
2746 NEXT_INSN (last) = b->rbi->footer;
2747 PREV_INSN (b->rbi->footer) = last;
2749 b->rbi->footer = NULL;
2753 fprintf (dump_file, "Merged blocks %d and %d.\n",
2754 a->index, b->index);
2760 cfg_layout_split_edge (edge e)
2763 basic_block new_bb =
2764 create_basic_block (e->src != ENTRY_BLOCK_PTR
2765 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2768 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2769 redirect_edge_and_branch_force (e, new_bb);
2774 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2777 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2781 /* Return 1 if BB ends with a call, possibly followed by some
2782 instructions that must stay with the call, 0 otherwise. */
2785 rtl_block_ends_with_call_p (basic_block bb)
2787 rtx insn = BB_END (bb);
2789 while (GET_CODE (insn) != CALL_INSN
2790 && insn != BB_HEAD (bb)
2791 && keep_with_call_p (insn))
2792 insn = PREV_INSN (insn);
2793 return (GET_CODE (insn) == CALL_INSN);
2796 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2799 rtl_block_ends_with_condjump_p (basic_block bb)
2801 return any_condjump_p (BB_END (bb));
2804 /* Return true if we need to add fake edge to exit.
2805 Helper function for rtl_flow_call_edges_add. */
2808 need_fake_edge_p (rtx insn)
2813 if ((GET_CODE (insn) == CALL_INSN
2814 && !SIBLING_CALL_P (insn)
2815 && !find_reg_note (insn, REG_NORETURN, NULL)
2816 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2817 && !CONST_OR_PURE_CALL_P (insn)))
2820 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2821 && MEM_VOLATILE_P (PATTERN (insn)))
2822 || (GET_CODE (PATTERN (insn)) == PARALLEL
2823 && asm_noperands (insn) != -1
2824 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2825 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2828 /* Add fake edges to the function exit for any non constant and non noreturn
2829 calls, volatile inline assembly in the bitmap of blocks specified by
2830 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2833 The goal is to expose cases in which entering a basic block does not imply
2834 that all subsequent instructions must be executed. */
2837 rtl_flow_call_edges_add (sbitmap blocks)
2840 int blocks_split = 0;
2841 int last_bb = last_basic_block;
2842 bool check_last_block = false;
2844 if (n_basic_blocks == 0)
2848 check_last_block = true;
2850 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2852 /* In the last basic block, before epilogue generation, there will be
2853 a fallthru edge to EXIT. Special care is required if the last insn
2854 of the last basic block is a call because make_edge folds duplicate
2855 edges, which would result in the fallthru edge also being marked
2856 fake, which would result in the fallthru edge being removed by
2857 remove_fake_edges, which would result in an invalid CFG.
2859 Moreover, we can't elide the outgoing fake edge, since the block
2860 profiler needs to take this into account in order to solve the minimal
2861 spanning tree in the case that the call doesn't return.
2863 Handle this by adding a dummy instruction in a new last basic block. */
2864 if (check_last_block)
2866 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2867 rtx insn = BB_END (bb);
2869 /* Back up past insns that must be kept in the same block as a call. */
2870 while (insn != BB_HEAD (bb)
2871 && keep_with_call_p (insn))
2872 insn = PREV_INSN (insn);
2874 if (need_fake_edge_p (insn))
2878 for (e = bb->succ; e; e = e->succ_next)
2879 if (e->dest == EXIT_BLOCK_PTR)
2881 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2882 commit_edge_insertions ();
2888 /* Now add fake edges to the function exit for any non constant
2889 calls since there is no way that we can determine if they will
2892 for (i = 0; i < last_bb; i++)
2894 basic_block bb = BASIC_BLOCK (i);
2901 if (blocks && !TEST_BIT (blocks, i))
2904 for (insn = BB_END (bb); ; insn = prev_insn)
2906 prev_insn = PREV_INSN (insn);
2907 if (need_fake_edge_p (insn))
2910 rtx split_at_insn = insn;
2912 /* Don't split the block between a call and an insn that should
2913 remain in the same block as the call. */
2914 if (GET_CODE (insn) == CALL_INSN)
2915 while (split_at_insn != BB_END (bb)
2916 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2917 split_at_insn = NEXT_INSN (split_at_insn);
2919 /* The handling above of the final block before the epilogue
2920 should be enough to verify that there is no edge to the exit
2921 block in CFG already. Calling make_edge in such case would
2922 cause us to mark that edge as fake and remove it later. */
2924 #ifdef ENABLE_CHECKING
2925 if (split_at_insn == BB_END (bb))
2926 for (e = bb->succ; e; e = e->succ_next)
2927 if (e->dest == EXIT_BLOCK_PTR)
2931 /* Note that the following may create a new basic block
2932 and renumber the existing basic blocks. */
2933 if (split_at_insn != BB_END (bb))
2935 e = split_block (bb, split_at_insn);
2940 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2943 if (insn == BB_HEAD (bb))
2949 verify_flow_info ();
2951 return blocks_split;
2954 /* Implementation of CFG manipulation for linearized RTL. */
2955 struct cfg_hooks rtl_cfg_hooks = {
2957 rtl_verify_flow_info,
2959 rtl_create_basic_block,
2960 rtl_redirect_edge_and_branch,
2961 rtl_redirect_edge_and_branch_force,
2964 rtl_move_block_after,
2965 rtl_can_merge_blocks, /* can_merge_blocks_p */
2969 NULL, /* can_duplicate_block_p */
2970 NULL, /* duplicate_block */
2972 rtl_make_forwarder_block,
2973 rtl_tidy_fallthru_edge,
2974 rtl_block_ends_with_call_p,
2975 rtl_block_ends_with_condjump_p,
2976 rtl_flow_call_edges_add
2979 /* Implementation of CFG manipulation for cfg layout RTL, where
2980 basic block connected via fallthru edges does not have to be adjacent.
2981 This representation will hopefully become the default one in future
2982 version of the compiler. */
2984 /* We do not want to declare these functions in a header file, since they
2985 should only be used through the cfghooks interface, and we do not want to
2986 move them here since it would require also moving quite a lot of related
2988 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
2989 extern basic_block cfg_layout_duplicate_bb (basic_block);
2991 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
2993 rtl_verify_flow_info_1,
2995 cfg_layout_create_basic_block,
2996 cfg_layout_redirect_edge_and_branch,
2997 cfg_layout_redirect_edge_and_branch_force,
2998 cfg_layout_delete_block,
2999 cfg_layout_split_block,
3000 rtl_move_block_after,
3001 cfg_layout_can_merge_blocks_p,
3002 cfg_layout_merge_blocks,
3005 cfg_layout_can_duplicate_bb_p,
3006 cfg_layout_duplicate_bb,
3007 cfg_layout_split_edge,
3008 rtl_make_forwarder_block,
3010 rtl_block_ends_with_call_p,
3011 rtl_block_ends_with_condjump_p,
3012 rtl_flow_call_edges_add