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, 2005, 2006, 2007, 2008, 2009
4 Free Software Foundation, Inc.
6 This file is part of GCC.
8 GCC is free software; you can redistribute it and/or modify it under
9 the terms of the GNU General Public License as published by the Free
10 Software Foundation; either version 3, or (at your option) any later
13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
15 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
18 You should have received a copy of the GNU General Public License
19 along with GCC; see the file COPYING3. If not see
20 <http://www.gnu.org/licenses/>. */
22 /* 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"
62 #include "tree-pass.h"
65 static int can_delete_note_p (const_rtx);
66 static int can_delete_label_p (const_rtx);
67 static void commit_one_edge_insertion (edge);
68 static basic_block rtl_split_edge (edge);
69 static bool rtl_move_block_after (basic_block, basic_block);
70 static int rtl_verify_flow_info (void);
71 static basic_block cfg_layout_split_block (basic_block, void *);
72 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
73 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
74 static void cfg_layout_delete_block (basic_block);
75 static void rtl_delete_block (basic_block);
76 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
77 static edge rtl_redirect_edge_and_branch (edge, basic_block);
78 static basic_block rtl_split_block (basic_block, void *);
79 static void rtl_dump_bb (basic_block, FILE *, int, int);
80 static int rtl_verify_flow_info_1 (void);
81 static void rtl_make_forwarder_block (edge);
83 /* Return true if NOTE is not one of the ones that must be kept paired,
84 so that we may simply delete it. */
87 can_delete_note_p (const_rtx note)
89 return (NOTE_KIND (note) == NOTE_INSN_DELETED
90 || NOTE_KIND (note) == NOTE_INSN_BASIC_BLOCK);
93 /* True if a given label can be deleted. */
96 can_delete_label_p (const_rtx label)
98 return (!LABEL_PRESERVE_P (label)
99 /* User declared labels must be preserved. */
100 && LABEL_NAME (label) == 0
101 && !in_expr_list_p (forced_labels, label));
104 /* Delete INSN by patching it out. Return the next insn. */
107 delete_insn (rtx insn)
109 rtx next = NEXT_INSN (insn);
111 bool really_delete = true;
115 /* Some labels can't be directly removed from the INSN chain, as they
116 might be references via variables, constant pool etc.
117 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
118 if (! can_delete_label_p (insn))
120 const char *name = LABEL_NAME (insn);
122 really_delete = false;
123 PUT_CODE (insn, NOTE);
124 NOTE_KIND (insn) = NOTE_INSN_DELETED_LABEL;
125 NOTE_DELETED_LABEL_NAME (insn) = name;
128 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
133 /* If this insn has already been deleted, something is very wrong. */
134 gcc_assert (!INSN_DELETED_P (insn));
136 INSN_DELETED_P (insn) = 1;
139 /* If deleting a jump, decrement the use count of the label. Deleting
140 the label itself should happen in the normal course of block merging. */
143 if (JUMP_LABEL (insn)
144 && LABEL_P (JUMP_LABEL (insn)))
145 LABEL_NUSES (JUMP_LABEL (insn))--;
147 /* If there are more targets, remove them too. */
149 = find_reg_note (insn, REG_LABEL_TARGET, NULL_RTX)) != NULL_RTX
150 && LABEL_P (XEXP (note, 0)))
152 LABEL_NUSES (XEXP (note, 0))--;
153 remove_note (insn, note);
157 /* Also if deleting any insn that references a label as an operand. */
158 while ((note = find_reg_note (insn, REG_LABEL_OPERAND, NULL_RTX)) != NULL_RTX
159 && LABEL_P (XEXP (note, 0)))
161 LABEL_NUSES (XEXP (note, 0))--;
162 remove_note (insn, note);
166 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
167 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
169 rtx pat = PATTERN (insn);
170 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
171 int len = XVECLEN (pat, diff_vec_p);
174 for (i = 0; i < len; i++)
176 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
178 /* When deleting code in bulk (e.g. removing many unreachable
179 blocks) we can delete a label that's a target of the vector
180 before deleting the vector itself. */
182 LABEL_NUSES (label)--;
189 /* 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. If CLEAR_BB is true, we set bb field for
209 insns that cannot be removed to NULL. */
212 delete_insn_chain (rtx start, rtx finish, bool clear_bb)
216 /* Unchain the insns one by one. It would be quicker to delete all of these
217 with a single unchaining, rather than one at a time, but we need to keep
221 next = NEXT_INSN (start);
222 if (NOTE_P (start) && !can_delete_note_p (start))
225 next = delete_insn (start);
227 if (clear_bb && !INSN_DELETED_P (start))
228 set_block_for_insn (start, NULL);
236 /* Create a new basic block consisting of the instructions between HEAD and END
237 inclusive. This function is designed to allow fast BB construction - reuses
238 the note and basic block struct in BB_NOTE, if any and do not grow
239 BASIC_BLOCK chain and should be used directly only by CFG construction code.
240 END can be NULL in to create new empty basic block before HEAD. Both END
241 and HEAD can be NULL to create basic block at the end of INSN chain.
242 AFTER is the basic block we should be put after. */
245 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
250 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
253 /* If we found an existing note, thread it back onto the chain. */
261 after = PREV_INSN (head);
265 if (after != bb_note && NEXT_INSN (after) != bb_note)
266 reorder_insns_nobb (bb_note, bb_note, after);
270 /* Otherwise we must create a note and a basic block structure. */
274 init_rtl_bb_info (bb);
277 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
278 else if (LABEL_P (head) && end)
280 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
286 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
292 NOTE_BASIC_BLOCK (bb_note) = bb;
295 /* Always include the bb note in the block. */
296 if (NEXT_INSN (end) == bb_note)
301 bb->index = last_basic_block++;
302 bb->flags = BB_NEW | BB_RTL;
303 link_block (bb, after);
304 SET_BASIC_BLOCK (bb->index, bb);
305 df_bb_refs_record (bb->index, false);
306 update_bb_for_insn (bb);
307 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
309 /* Tag the block so that we know it has been used when considering
310 other basic block notes. */
316 /* Create new basic block consisting of instructions in between HEAD and END
317 and place it to the BB chain after block AFTER. END can be NULL in to
318 create new empty basic block before HEAD. Both END and HEAD can be NULL to
319 create basic block at the end of INSN chain. */
322 rtl_create_basic_block (void *headp, void *endp, basic_block after)
324 rtx head = (rtx) headp, end = (rtx) endp;
327 /* Grow the basic block array if needed. */
328 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info))
330 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
331 VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size);
336 bb = create_basic_block_structure (head, end, NULL, after);
342 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
344 basic_block newbb = rtl_create_basic_block (head, end, after);
349 /* Delete the insns in a (non-live) block. We physically delete every
350 non-deleted-note insn, and update the flow graph appropriately.
352 Return nonzero if we deleted an exception handler. */
354 /* ??? Preserving all such notes strikes me as wrong. It would be nice
355 to post-process the stream to remove empty blocks, loops, ranges, etc. */
358 rtl_delete_block (basic_block b)
362 /* If the head of this block is a CODE_LABEL, then it might be the
363 label for an exception handler which can't be reached. We need
364 to remove the label from the exception_handler_label list. */
367 end = get_last_bb_insn (b);
369 /* Selectively delete the entire chain. */
371 delete_insn_chain (insn, end, true);
375 fprintf (dump_file, "deleting block %d\n", b->index);
376 df_bb_delete (b->index);
379 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
382 compute_bb_for_insn (void)
388 rtx end = BB_END (bb);
391 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
393 BLOCK_FOR_INSN (insn) = bb;
400 /* Release the basic_block_for_insn array. */
403 free_bb_for_insn (void)
406 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
407 if (!BARRIER_P (insn))
408 BLOCK_FOR_INSN (insn) = NULL;
412 struct rtl_opt_pass pass_free_cfg =
418 free_bb_for_insn, /* execute */
421 0, /* static_pass_number */
423 0, /* properties_required */
424 0, /* properties_provided */
425 PROP_cfg, /* properties_destroyed */
426 0, /* todo_flags_start */
427 0, /* todo_flags_finish */
431 /* Return RTX to emit after when we want to emit code on the entry of function. */
433 entry_of_function (void)
435 return (n_basic_blocks > NUM_FIXED_BLOCKS ?
436 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
439 /* Emit INSN at the entry point of the function, ensuring that it is only
440 executed once per function. */
442 emit_insn_at_entry (rtx insn)
444 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs);
445 edge e = ei_safe_edge (ei);
446 gcc_assert (e->flags & EDGE_FALLTHRU);
448 insert_insn_on_edge (insn, e);
449 commit_edge_insertions ();
452 /* Update BLOCK_FOR_INSN of insns between BEGIN and END
453 (or BARRIER if found) and notify df of the bb change.
454 The insn chain range is inclusive
455 (i.e. both BEGIN and END will be updated. */
458 update_bb_for_insn_chain (rtx begin, rtx end, basic_block bb)
462 end = NEXT_INSN (end);
463 for (insn = begin; insn != end; insn = NEXT_INSN (insn))
464 if (!BARRIER_P (insn))
465 df_insn_change_bb (insn, bb);
468 /* Update BLOCK_FOR_INSN of insns in BB to BB,
469 and notify df of the change. */
472 update_bb_for_insn (basic_block bb)
474 update_bb_for_insn_chain (BB_HEAD (bb), BB_END (bb), bb);
478 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
479 note associated with the BLOCK. */
482 first_insn_after_basic_block_note (basic_block block)
486 /* Get the first instruction in the block. */
487 insn = BB_HEAD (block);
489 if (insn == NULL_RTX)
492 insn = NEXT_INSN (insn);
493 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
495 return NEXT_INSN (insn);
498 /* Creates a new basic block just after basic block B by splitting
499 everything after specified instruction I. */
502 rtl_split_block (basic_block bb, void *insnp)
505 rtx insn = (rtx) insnp;
511 insn = first_insn_after_basic_block_note (bb);
514 insn = PREV_INSN (insn);
516 insn = get_last_insn ();
519 /* We probably should check type of the insn so that we do not create
520 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
522 if (insn == BB_END (bb))
523 emit_note_after (NOTE_INSN_DELETED, insn);
525 /* Create the new basic block. */
526 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
527 BB_COPY_PARTITION (new_bb, bb);
530 /* Redirect the outgoing edges. */
531 new_bb->succs = bb->succs;
533 FOR_EACH_EDGE (e, ei, new_bb->succs)
536 /* The new block starts off being dirty. */
537 df_set_bb_dirty (bb);
541 /* Blocks A and B are to be merged into a single block A. The insns
542 are already contiguous. */
545 rtl_merge_blocks (basic_block a, basic_block b)
547 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
548 rtx del_first = NULL_RTX, del_last = NULL_RTX;
552 fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
554 /* If there was a CODE_LABEL beginning B, delete it. */
555 if (LABEL_P (b_head))
557 /* Detect basic blocks with nothing but a label. This can happen
558 in particular at the end of a function. */
562 del_first = del_last = b_head;
563 b_head = NEXT_INSN (b_head);
566 /* Delete the basic block note and handle blocks containing just that
568 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
576 b_head = NEXT_INSN (b_head);
579 /* If there was a jump out of A, delete it. */
584 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
586 || NOTE_INSN_BASIC_BLOCK_P (prev)
587 || prev == BB_HEAD (a))
593 /* If this was a conditional jump, we need to also delete
594 the insn that set cc0. */
595 if (only_sets_cc0_p (prev))
599 prev = prev_nonnote_insn (prev);
606 a_end = PREV_INSN (del_first);
608 else if (BARRIER_P (NEXT_INSN (a_end)))
609 del_first = NEXT_INSN (a_end);
611 /* Delete everything marked above as well as crap that might be
612 hanging out between the two blocks. */
614 delete_insn_chain (del_first, del_last, true);
616 /* Reassociate the insns of B with A. */
619 update_bb_for_insn_chain (a_end, b_end, a);
624 df_bb_delete (b->index);
629 /* Return true when block A and B can be merged. */
632 rtl_can_merge_blocks (basic_block a, basic_block b)
634 /* If we are partitioning hot/cold basic blocks, we don't want to
635 mess up unconditional or indirect jumps that cross between hot
638 Basic block partitioning may result in some jumps that appear to
639 be optimizable (or blocks that appear to be mergeable), but which really
640 must be left untouched (they are required to make it safely across
641 partition boundaries). See the comments at the top of
642 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
644 if (BB_PARTITION (a) != BB_PARTITION (b))
647 /* There must be exactly one edge in between the blocks. */
648 return (single_succ_p (a)
649 && single_succ (a) == b
652 /* Must be simple edge. */
653 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
655 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
656 /* If the jump insn has side effects,
657 we can't kill the edge. */
658 && (!JUMP_P (BB_END (a))
660 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
663 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
667 block_label (basic_block block)
669 if (block == EXIT_BLOCK_PTR)
672 if (!LABEL_P (BB_HEAD (block)))
674 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
677 return BB_HEAD (block);
680 /* Attempt to perform edge redirection by replacing possibly complex jump
681 instruction by unconditional jump or removing jump completely. This can
682 apply only if all edges now point to the same block. The parameters and
683 return values are equivalent to redirect_edge_and_branch. */
686 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
688 basic_block src = e->src;
689 rtx insn = BB_END (src), kill_from;
693 /* If we are partitioning hot/cold basic blocks, we don't want to
694 mess up unconditional or indirect jumps that cross between hot
697 Basic block partitioning may result in some jumps that appear to
698 be optimizable (or blocks that appear to be mergeable), but which really
699 must be left untouched (they are required to make it safely across
700 partition boundaries). See the comments at the top of
701 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
703 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
704 || BB_PARTITION (src) != BB_PARTITION (target))
707 /* We can replace or remove a complex jump only when we have exactly
708 two edges. Also, if we have exactly one outgoing edge, we can
710 if (EDGE_COUNT (src->succs) >= 3
711 /* Verify that all targets will be TARGET. Specifically, the
712 edge that is not E must also go to TARGET. */
713 || (EDGE_COUNT (src->succs) == 2
714 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
717 if (!onlyjump_p (insn))
719 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
722 /* Avoid removing branch with side effects. */
723 set = single_set (insn);
724 if (!set || side_effects_p (set))
727 /* In case we zap a conditional jump, we'll need to kill
728 the cc0 setter too. */
731 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
732 && only_sets_cc0_p (PREV_INSN (insn)))
733 kill_from = PREV_INSN (insn);
736 /* See if we can create the fallthru edge. */
737 if (in_cfglayout || can_fallthru (src, target))
740 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
743 /* Selectively unlink whole insn chain. */
746 rtx insn = src->il.rtl->footer;
748 delete_insn_chain (kill_from, BB_END (src), false);
750 /* Remove barriers but keep jumptables. */
753 if (BARRIER_P (insn))
755 if (PREV_INSN (insn))
756 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
758 src->il.rtl->footer = NEXT_INSN (insn);
759 if (NEXT_INSN (insn))
760 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
764 insn = NEXT_INSN (insn);
768 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
772 /* If this already is simplejump, redirect it. */
773 else if (simplejump_p (insn))
775 if (e->dest == target)
778 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
779 INSN_UID (insn), e->dest->index, target->index);
780 if (!redirect_jump (insn, block_label (target), 0))
782 gcc_assert (target == EXIT_BLOCK_PTR);
787 /* Cannot do anything for target exit block. */
788 else if (target == EXIT_BLOCK_PTR)
791 /* Or replace possibly complicated jump insn by simple jump insn. */
794 rtx target_label = block_label (target);
795 rtx barrier, label, table;
797 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
798 JUMP_LABEL (BB_END (src)) = target_label;
799 LABEL_NUSES (target_label)++;
801 fprintf (dump_file, "Replacing insn %i by jump %i\n",
802 INSN_UID (insn), INSN_UID (BB_END (src)));
805 delete_insn_chain (kill_from, insn, false);
807 /* Recognize a tablejump that we are converting to a
808 simple jump and remove its associated CODE_LABEL
809 and ADDR_VEC or ADDR_DIFF_VEC. */
810 if (tablejump_p (insn, &label, &table))
811 delete_insn_chain (label, table, false);
813 barrier = next_nonnote_insn (BB_END (src));
814 if (!barrier || !BARRIER_P (barrier))
815 emit_barrier_after (BB_END (src));
818 if (barrier != NEXT_INSN (BB_END (src)))
820 /* Move the jump before barrier so that the notes
821 which originally were or were created before jump table are
822 inside the basic block. */
823 rtx new_insn = BB_END (src);
825 update_bb_for_insn_chain (NEXT_INSN (BB_END (src)),
826 PREV_INSN (barrier), src);
828 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
829 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
831 NEXT_INSN (new_insn) = barrier;
832 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
834 PREV_INSN (new_insn) = PREV_INSN (barrier);
835 PREV_INSN (barrier) = new_insn;
840 /* Keep only one edge out and set proper flags. */
841 if (!single_succ_p (src))
843 gcc_assert (single_succ_p (src));
845 e = single_succ_edge (src);
847 e->flags = EDGE_FALLTHRU;
851 e->probability = REG_BR_PROB_BASE;
852 e->count = src->count;
854 if (e->dest != target)
855 redirect_edge_succ (e, target);
859 /* Redirect edge representing branch of (un)conditional jump or tablejump,
862 redirect_branch_edge (edge e, basic_block target)
865 rtx old_label = BB_HEAD (e->dest);
866 basic_block src = e->src;
867 rtx insn = BB_END (src);
869 /* We can only redirect non-fallthru edges of jump insn. */
870 if (e->flags & EDGE_FALLTHRU)
872 else if (!JUMP_P (insn))
875 /* Recognize a tablejump and adjust all matching cases. */
876 if (tablejump_p (insn, NULL, &tmp))
880 rtx new_label = block_label (target);
882 if (target == EXIT_BLOCK_PTR)
884 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
885 vec = XVEC (PATTERN (tmp), 0);
887 vec = XVEC (PATTERN (tmp), 1);
889 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
890 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
892 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
893 --LABEL_NUSES (old_label);
894 ++LABEL_NUSES (new_label);
897 /* Handle casesi dispatch insns. */
898 if ((tmp = single_set (insn)) != NULL
899 && SET_DEST (tmp) == pc_rtx
900 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
901 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
902 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
904 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
906 --LABEL_NUSES (old_label);
907 ++LABEL_NUSES (new_label);
912 /* ?? We may play the games with moving the named labels from
913 one basic block to the other in case only one computed_jump is
915 if (computed_jump_p (insn)
916 /* A return instruction can't be redirected. */
917 || returnjump_p (insn))
920 /* If the insn doesn't go where we think, we're confused. */
921 gcc_assert (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 gcc_assert (target == EXIT_BLOCK_PTR);
934 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
935 e->src->index, e->dest->index, target->index);
937 if (e->dest != target)
938 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 df_set_bb_dirty (src);
972 ret = redirect_branch_edge (e, target);
976 df_set_bb_dirty (src);
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;
992 /* In the case the last instruction is conditional jump to the next
993 instruction, first redirect the jump itself and then continue
994 by creating a basic block afterwards to redirect fallthru edge. */
995 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
996 && any_condjump_p (BB_END (e->src))
997 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1000 edge b = unchecked_make_edge (e->src, target, 0);
1003 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1004 gcc_assert (redirected);
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 gcc_assert (e->dest == target);
1030 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1031 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1035 gcc_assert (e->flags & EDGE_FALLTHRU);
1036 if (e->src == ENTRY_BLOCK_PTR)
1038 /* We can't redirect the entry block. Create an empty block
1039 at the start of the function which we use to add the new
1045 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1047 /* Change the existing edge's source to be the new block, and add
1048 a new edge from the entry block to the new block. */
1050 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1054 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1064 VEC_safe_push (edge, gc, bb->succs, e);
1065 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1069 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1071 /* Create the new structures. */
1073 /* If the old block ended with a tablejump, skip its table
1074 by searching forward from there. Otherwise start searching
1075 forward from the last instruction of the old block. */
1076 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1077 note = BB_END (e->src);
1078 note = NEXT_INSN (note);
1080 jump_block = create_basic_block (note, NULL, e->src);
1081 jump_block->count = e->count;
1082 jump_block->frequency = EDGE_FREQUENCY (e);
1083 jump_block->loop_depth = target->loop_depth;
1085 /* Make sure new block ends up in correct hot/cold section. */
1087 BB_COPY_PARTITION (jump_block, e->src);
1088 if (flag_reorder_blocks_and_partition
1089 && targetm.have_named_sections
1090 && JUMP_P (BB_END (jump_block))
1091 && !any_condjump_p (BB_END (jump_block))
1092 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1093 add_reg_note (BB_END (jump_block), REG_CROSSING_JUMP, NULL_RTX);
1096 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1097 new_edge->probability = e->probability;
1098 new_edge->count = e->count;
1100 /* Redirect old edge. */
1101 redirect_edge_pred (e, jump_block);
1102 e->probability = REG_BR_PROB_BASE;
1104 new_bb = jump_block;
1107 jump_block = e->src;
1109 if (e->goto_locus && e->goto_block == NULL)
1110 loc = e->goto_locus;
1113 e->flags &= ~EDGE_FALLTHRU;
1114 if (target == EXIT_BLOCK_PTR)
1117 emit_jump_insn_after_setloc (gen_return (), BB_END (jump_block), loc);
1124 rtx label = block_label (target);
1125 emit_jump_insn_after_setloc (gen_jump (label), BB_END (jump_block), loc);
1126 JUMP_LABEL (BB_END (jump_block)) = label;
1127 LABEL_NUSES (label)++;
1130 emit_barrier_after (BB_END (jump_block));
1131 redirect_edge_succ_nodup (e, target);
1133 if (abnormal_edge_flags)
1134 make_edge (src, target, abnormal_edge_flags);
1136 df_mark_solutions_dirty ();
1140 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1141 (and possibly create new basic block) to make edge non-fallthru.
1142 Return newly created BB or NULL if none. */
1145 force_nonfallthru (edge e)
1147 return force_nonfallthru_and_redirect (e, e->dest);
1150 /* Redirect edge even at the expense of creating new jump insn or
1151 basic block. Return new basic block if created, NULL otherwise.
1152 Conversion must be possible. */
1155 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1157 if (redirect_edge_and_branch (e, target)
1158 || e->dest == target)
1161 /* In case the edge redirection failed, try to force it to be non-fallthru
1162 and redirect newly created simplejump. */
1163 df_set_bb_dirty (e->src);
1164 return force_nonfallthru_and_redirect (e, target);
1167 /* The given edge should potentially be a fallthru edge. If that is in
1168 fact true, delete the jump and barriers that are in the way. */
1171 rtl_tidy_fallthru_edge (edge e)
1174 basic_block b = e->src, c = b->next_bb;
1176 /* ??? In a late-running flow pass, other folks may have deleted basic
1177 blocks by nopping out blocks, leaving multiple BARRIERs between here
1178 and the target label. They ought to be chastised and fixed.
1180 We can also wind up with a sequence of undeletable labels between
1181 one block and the next.
1183 So search through a sequence of barriers, labels, and notes for
1184 the head of block C and assert that we really do fall through. */
1186 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1190 /* Remove what will soon cease being the jump insn from the source block.
1191 If block B consisted only of this single jump, turn it into a deleted
1196 && (any_uncondjump_p (q)
1197 || single_succ_p (b)))
1200 /* If this was a conditional jump, we need to also delete
1201 the insn that set cc0. */
1202 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1209 /* Selectively unlink the sequence. */
1210 if (q != PREV_INSN (BB_HEAD (c)))
1211 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false);
1213 e->flags |= EDGE_FALLTHRU;
1216 /* Should move basic block BB after basic block AFTER. NIY. */
1219 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1220 basic_block after ATTRIBUTE_UNUSED)
1225 /* Split a (typically critical) edge. Return the new block.
1226 The edge must not be abnormal.
1228 ??? The code generally expects to be called on critical edges.
1229 The case of a block ending in an unconditional jump to a
1230 block with multiple predecessors is not handled optimally. */
1233 rtl_split_edge (edge edge_in)
1238 /* Abnormal edges cannot be split. */
1239 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1241 /* We are going to place the new block in front of edge destination.
1242 Avoid existence of fallthru predecessors. */
1243 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1248 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1249 if (e->flags & EDGE_FALLTHRU)
1253 force_nonfallthru (e);
1256 /* Create the basic block note. */
1257 if (edge_in->dest != EXIT_BLOCK_PTR)
1258 before = BB_HEAD (edge_in->dest);
1262 /* If this is a fall through edge to the exit block, the blocks might be
1263 not adjacent, and the right place is the after the source. */
1264 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1266 before = NEXT_INSN (BB_END (edge_in->src));
1267 bb = create_basic_block (before, NULL, edge_in->src);
1268 BB_COPY_PARTITION (bb, edge_in->src);
1272 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1273 /* ??? Why not edge_in->dest->prev_bb here? */
1274 BB_COPY_PARTITION (bb, edge_in->dest);
1277 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1279 /* For non-fallthru edges, we must adjust the predecessor's
1280 jump instruction to target our new block. */
1281 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1283 edge redirected = redirect_edge_and_branch (edge_in, bb);
1284 gcc_assert (redirected);
1287 redirect_edge_succ (edge_in, bb);
1292 /* Queue instructions for insertion on an edge between two basic blocks.
1293 The new instructions and basic blocks (if any) will not appear in the
1294 CFG until commit_edge_insertions is called. */
1297 insert_insn_on_edge (rtx pattern, edge e)
1299 /* We cannot insert instructions on an abnormal critical edge.
1300 It will be easier to find the culprit if we die now. */
1301 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1303 if (e->insns.r == NULL_RTX)
1306 push_to_sequence (e->insns.r);
1308 emit_insn (pattern);
1310 e->insns.r = get_insns ();
1314 /* Update the CFG for the instructions queued on edge E. */
1317 commit_one_edge_insertion (edge e)
1319 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1320 basic_block bb = NULL;
1322 /* Pull the insns off the edge now since the edge might go away. */
1324 e->insns.r = NULL_RTX;
1326 if (!before && !after)
1328 /* Figure out where to put these things. If the destination has
1329 one predecessor, insert there. Except for the exit block. */
1330 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1334 /* Get the location correct wrt a code label, and "nice" wrt
1335 a basic block note, and before everything else. */
1338 tmp = NEXT_INSN (tmp);
1339 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1340 tmp = NEXT_INSN (tmp);
1341 if (tmp == BB_HEAD (bb))
1344 after = PREV_INSN (tmp);
1346 after = get_last_insn ();
1349 /* If the source has one successor and the edge is not abnormal,
1350 insert there. Except for the entry block. */
1351 else if ((e->flags & EDGE_ABNORMAL) == 0
1352 && single_succ_p (e->src)
1353 && e->src != ENTRY_BLOCK_PTR)
1357 /* It is possible to have a non-simple jump here. Consider a target
1358 where some forms of unconditional jumps clobber a register. This
1359 happens on the fr30 for example.
1361 We know this block has a single successor, so we can just emit
1362 the queued insns before the jump. */
1363 if (JUMP_P (BB_END (bb)))
1364 before = BB_END (bb);
1367 /* We'd better be fallthru, or we've lost track of
1369 gcc_assert (e->flags & EDGE_FALLTHRU);
1371 after = BB_END (bb);
1374 /* Otherwise we must split the edge. */
1377 bb = split_edge (e);
1378 after = BB_END (bb);
1380 if (flag_reorder_blocks_and_partition
1381 && targetm.have_named_sections
1382 && e->src != ENTRY_BLOCK_PTR
1383 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1384 && !(e->flags & EDGE_CROSSING))
1386 rtx bb_note, cur_insn;
1389 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1390 cur_insn = NEXT_INSN (cur_insn))
1391 if (NOTE_INSN_BASIC_BLOCK_P (cur_insn))
1397 if (JUMP_P (BB_END (bb))
1398 && !any_condjump_p (BB_END (bb))
1399 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1400 add_reg_note (BB_END (bb), REG_CROSSING_JUMP, NULL_RTX);
1405 /* Now that we've found the spot, do the insertion. */
1409 emit_insn_before_noloc (insns, before, bb);
1410 last = prev_nonnote_insn (before);
1413 last = emit_insn_after_noloc (insns, after, bb);
1415 if (returnjump_p (last))
1417 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1418 This is not currently a problem because this only happens
1419 for the (single) epilogue, which already has a fallthru edge
1422 e = single_succ_edge (bb);
1423 gcc_assert (e->dest == EXIT_BLOCK_PTR
1424 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1426 e->flags &= ~EDGE_FALLTHRU;
1427 emit_barrier_after (last);
1430 delete_insn (before);
1433 gcc_assert (!JUMP_P (last));
1435 /* Mark the basic block for find_many_sub_basic_blocks. */
1436 if (current_ir_type () != IR_RTL_CFGLAYOUT)
1440 /* Update the CFG for all queued instructions. */
1443 commit_edge_insertions (void)
1447 bool changed = false;
1449 #ifdef ENABLE_CHECKING
1450 verify_flow_info ();
1453 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1458 FOR_EACH_EDGE (e, ei, bb->succs)
1462 commit_one_edge_insertion (e);
1469 /* In the old rtl CFG API, it was OK to insert control flow on an
1470 edge, apparently? In cfglayout mode, this will *not* work, and
1471 the caller is responsible for making sure that control flow is
1472 valid at all times. */
1473 if (current_ir_type () == IR_RTL_CFGLAYOUT)
1476 blocks = sbitmap_alloc (last_basic_block);
1477 sbitmap_zero (blocks);
1481 SET_BIT (blocks, bb->index);
1482 /* Check for forgotten bb->aux values before commit_edge_insertions
1484 gcc_assert (bb->aux == &bb->aux);
1487 find_many_sub_basic_blocks (blocks);
1488 sbitmap_free (blocks);
1492 /* Print out RTL-specific basic block information (live information
1493 at start and end). */
1496 rtl_dump_bb (basic_block bb, FILE *outf, int indent, int flags ATTRIBUTE_UNUSED)
1502 s_indent = (char *) alloca ((size_t) indent + 1);
1503 memset (s_indent, ' ', (size_t) indent);
1504 s_indent[indent] = '\0';
1508 df_dump_top (bb, outf);
1512 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1513 insn = NEXT_INSN (insn))
1514 print_rtl_single (outf, insn);
1518 df_dump_bottom (bb, outf);
1524 /* Like print_rtl, but also print out live information for the start of each
1528 print_rtl_with_bb (FILE *outf, const_rtx rtx_first)
1532 fprintf (outf, "(nil)\n");
1535 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1536 int max_uid = get_max_uid ();
1537 basic_block *start = XCNEWVEC (basic_block, max_uid);
1538 basic_block *end = XCNEWVEC (basic_block, max_uid);
1539 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1544 df_dump_start (outf);
1546 FOR_EACH_BB_REVERSE (bb)
1550 start[INSN_UID (BB_HEAD (bb))] = bb;
1551 end[INSN_UID (BB_END (bb))] = bb;
1552 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1554 enum bb_state state = IN_MULTIPLE_BB;
1556 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1558 in_bb_p[INSN_UID (x)] = state;
1560 if (x == BB_END (bb))
1565 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1568 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1573 fprintf (outf, ";; Start of basic block (");
1574 FOR_EACH_EDGE (e, ei, bb->preds)
1575 fprintf (outf, " %d", e->src->index);
1576 fprintf (outf, ") -> %d\n", bb->index);
1580 df_dump_top (bb, outf);
1583 FOR_EACH_EDGE (e, ei, bb->preds)
1585 fputs (";; Pred edge ", outf);
1586 dump_edge_info (outf, e, 0);
1591 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1592 && !NOTE_P (tmp_rtx)
1593 && !BARRIER_P (tmp_rtx))
1594 fprintf (outf, ";; Insn is not within a basic block\n");
1595 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1596 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1598 did_output = print_rtl_single (outf, tmp_rtx);
1600 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1605 fprintf (outf, ";; End of basic block %d -> (", bb->index);
1606 FOR_EACH_EDGE (e, ei, bb->succs)
1607 fprintf (outf, " %d", e->dest->index);
1608 fprintf (outf, ")\n");
1612 df_dump_bottom (bb, outf);
1616 FOR_EACH_EDGE (e, ei, bb->succs)
1618 fputs (";; Succ edge ", outf);
1619 dump_edge_info (outf, e, 1);
1632 if (crtl->epilogue_delay_list != 0)
1634 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1635 for (tmp_rtx = crtl->epilogue_delay_list; tmp_rtx != 0;
1636 tmp_rtx = XEXP (tmp_rtx, 1))
1637 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1642 update_br_prob_note (basic_block bb)
1645 if (!JUMP_P (BB_END (bb)))
1647 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1648 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1650 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1653 /* Get the last insn associated with block BB (that includes barriers and
1654 tablejumps after BB). */
1656 get_last_bb_insn (basic_block bb)
1659 rtx end = BB_END (bb);
1661 /* Include any jump table following the basic block. */
1662 if (tablejump_p (end, NULL, &tmp))
1665 /* Include any barriers that may follow the basic block. */
1666 tmp = next_nonnote_insn (end);
1667 while (tmp && BARRIER_P (tmp))
1670 tmp = next_nonnote_insn (end);
1676 /* Verify the CFG and RTL consistency common for both underlying RTL and
1679 Currently it does following checks:
1681 - overlapping of basic blocks
1682 - insns with wrong BLOCK_FOR_INSN pointers
1683 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1684 - tails of basic blocks (ensure that boundary is necessary)
1685 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1686 and NOTE_INSN_BASIC_BLOCK
1687 - verify that no fall_thru edge crosses hot/cold partition boundaries
1688 - verify that there are no pending RTL branch predictions
1690 In future it can be extended check a lot of other stuff as well
1691 (reachability of basic blocks, life information, etc. etc.). */
1694 rtl_verify_flow_info_1 (void)
1700 /* Check the general integrity of the basic blocks. */
1701 FOR_EACH_BB_REVERSE (bb)
1705 if (!(bb->flags & BB_RTL))
1707 error ("BB_RTL flag not set for block %d", bb->index);
1711 FOR_BB_INSNS (bb, insn)
1712 if (BLOCK_FOR_INSN (insn) != bb)
1714 error ("insn %d basic block pointer is %d, should be %d",
1716 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1721 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1722 if (!BARRIER_P (insn)
1723 && BLOCK_FOR_INSN (insn) != NULL)
1725 error ("insn %d in header of bb %d has non-NULL basic block",
1726 INSN_UID (insn), bb->index);
1729 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1730 if (!BARRIER_P (insn)
1731 && BLOCK_FOR_INSN (insn) != NULL)
1733 error ("insn %d in footer of bb %d has non-NULL basic block",
1734 INSN_UID (insn), bb->index);
1739 /* Now check the basic blocks (boundaries etc.) */
1740 FOR_EACH_BB_REVERSE (bb)
1742 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1743 edge e, fallthru = NULL;
1747 if (JUMP_P (BB_END (bb))
1748 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1749 && EDGE_COUNT (bb->succs) >= 2
1750 && any_condjump_p (BB_END (bb)))
1752 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1753 && profile_status != PROFILE_ABSENT)
1755 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1756 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1760 FOR_EACH_EDGE (e, ei, bb->succs)
1762 if (e->flags & EDGE_FALLTHRU)
1764 n_fallthru++, fallthru = e;
1765 if ((e->flags & EDGE_CROSSING)
1766 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1767 && e->src != ENTRY_BLOCK_PTR
1768 && e->dest != EXIT_BLOCK_PTR))
1770 error ("fallthru edge crosses section boundary (bb %i)",
1776 if ((e->flags & ~(EDGE_DFS_BACK
1778 | EDGE_IRREDUCIBLE_LOOP
1780 | EDGE_CROSSING)) == 0)
1783 if (e->flags & EDGE_ABNORMAL_CALL)
1786 if (e->flags & EDGE_EH)
1788 else if (e->flags & EDGE_ABNORMAL)
1792 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
1793 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1795 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1799 && (!JUMP_P (BB_END (bb))
1800 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1801 || any_condjump_p (BB_END (bb))))))
1803 error ("too many outgoing branch edges from bb %i", bb->index);
1806 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1808 error ("fallthru edge after unconditional jump %i", bb->index);
1811 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1813 error ("wrong amount of branch edges after unconditional jump %i", bb->index);
1816 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1817 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1819 error ("wrong amount of branch edges after conditional jump %i",
1823 if (n_call && !CALL_P (BB_END (bb)))
1825 error ("call edges for non-call insn in bb %i", bb->index);
1829 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1830 && (!JUMP_P (BB_END (bb))
1831 || any_condjump_p (BB_END (bb))
1832 || any_uncondjump_p (BB_END (bb))))
1834 error ("abnormal edges for no purpose in bb %i", bb->index);
1838 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1839 /* We may have a barrier inside a basic block before dead code
1840 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1841 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1844 if (! BLOCK_FOR_INSN (x))
1846 ("insn %d inside basic block %d but block_for_insn is NULL",
1847 INSN_UID (x), bb->index);
1850 ("insn %d inside basic block %d but block_for_insn is %i",
1851 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1856 /* OK pointers are correct. Now check the header of basic
1857 block. It ought to contain optional CODE_LABEL followed
1858 by NOTE_BASIC_BLOCK. */
1862 if (BB_END (bb) == x)
1864 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1872 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1874 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1879 if (BB_END (bb) == x)
1880 /* Do checks for empty blocks here. */
1883 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1885 if (NOTE_INSN_BASIC_BLOCK_P (x))
1887 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1888 INSN_UID (x), bb->index);
1892 if (x == BB_END (bb))
1895 if (control_flow_insn_p (x))
1897 error ("in basic block %d:", bb->index);
1898 fatal_insn ("flow control insn inside a basic block", x);
1907 /* Verify the CFG and RTL consistency common for both underlying RTL and
1910 Currently it does following checks:
1911 - all checks of rtl_verify_flow_info_1
1912 - test head/end pointers
1913 - check that all insns are in the basic blocks
1914 (except the switch handling code, barriers and notes)
1915 - check that all returns are followed by barriers
1916 - check that all fallthru edge points to the adjacent blocks. */
1919 rtl_verify_flow_info (void)
1922 int err = rtl_verify_flow_info_1 ();
1924 rtx last_head = get_last_insn ();
1925 basic_block *bb_info;
1927 const rtx rtx_first = get_insns ();
1928 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
1929 const int max_uid = get_max_uid ();
1931 bb_info = XCNEWVEC (basic_block, max_uid);
1933 FOR_EACH_BB_REVERSE (bb)
1937 rtx head = BB_HEAD (bb);
1938 rtx end = BB_END (bb);
1940 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1942 /* Verify the end of the basic block is in the INSN chain. */
1946 /* And that the code outside of basic blocks has NULL bb field. */
1948 && BLOCK_FOR_INSN (x) != NULL)
1950 error ("insn %d outside of basic blocks has non-NULL bb field",
1958 error ("end insn %d for block %d not found in the insn stream",
1959 INSN_UID (end), bb->index);
1963 /* Work backwards from the end to the head of the basic block
1964 to verify the head is in the RTL chain. */
1965 for (; x != NULL_RTX; x = PREV_INSN (x))
1967 /* While walking over the insn chain, verify insns appear
1968 in only one basic block. */
1969 if (bb_info[INSN_UID (x)] != NULL)
1971 error ("insn %d is in multiple basic blocks (%d and %d)",
1972 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1976 bb_info[INSN_UID (x)] = bb;
1983 error ("head insn %d for block %d not found in the insn stream",
1984 INSN_UID (head), bb->index);
1988 last_head = PREV_INSN (x);
1990 FOR_EACH_EDGE (e, ei, bb->succs)
1991 if (e->flags & EDGE_FALLTHRU)
1997 /* Ensure existence of barrier in BB with no fallthru edges. */
1998 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
1999 insn = NEXT_INSN (insn))
2001 || NOTE_INSN_BASIC_BLOCK_P (insn))
2003 error ("missing barrier after block %i", bb->index);
2008 else if (e->src != ENTRY_BLOCK_PTR
2009 && e->dest != EXIT_BLOCK_PTR)
2013 if (e->src->next_bb != e->dest)
2016 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2017 e->src->index, e->dest->index);
2021 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2022 insn = NEXT_INSN (insn))
2023 if (BARRIER_P (insn) || INSN_P (insn))
2025 error ("verify_flow_info: Incorrect fallthru %i->%i",
2026 e->src->index, e->dest->index);
2027 fatal_insn ("wrong insn in the fallthru edge", insn);
2033 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2035 /* Check that the code before the first basic block has NULL
2038 && BLOCK_FOR_INSN (x) != NULL)
2040 error ("insn %d outside of basic blocks has non-NULL bb field",
2048 last_bb_seen = ENTRY_BLOCK_PTR;
2050 for (x = rtx_first; x; x = NEXT_INSN (x))
2052 if (NOTE_INSN_BASIC_BLOCK_P (x))
2054 bb = NOTE_BASIC_BLOCK (x);
2057 if (bb != last_bb_seen->next_bb)
2058 internal_error ("basic blocks not laid down consecutively");
2060 curr_bb = last_bb_seen = bb;
2065 switch (GET_CODE (x))
2072 /* An addr_vec is placed outside any basic block. */
2074 && JUMP_P (NEXT_INSN (x))
2075 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2076 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2079 /* But in any case, non-deletable labels can appear anywhere. */
2083 fatal_insn ("insn outside basic block", x);
2088 && returnjump_p (x) && ! condjump_p (x)
2089 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2090 fatal_insn ("return not followed by barrier", x);
2091 if (curr_bb && x == BB_END (curr_bb))
2095 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2097 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2098 num_bb_notes, n_basic_blocks);
2103 /* Assume that the preceding pass has possibly eliminated jump instructions
2104 or converted the unconditional jumps. Eliminate the edges from CFG.
2105 Return true if any edges are eliminated. */
2108 purge_dead_edges (basic_block bb)
2111 rtx insn = BB_END (bb), note;
2112 bool purged = false;
2116 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2117 if (NONJUMP_INSN_P (insn)
2118 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2122 if (! may_trap_p (PATTERN (insn))
2123 || ((eqnote = find_reg_equal_equiv_note (insn))
2124 && ! may_trap_p (XEXP (eqnote, 0))))
2125 remove_note (insn, note);
2128 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2129 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2131 /* There are three types of edges we need to handle correctly here: EH
2132 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2133 latter can appear when nonlocal gotos are used. */
2134 if (e->flags & EDGE_EH)
2136 if (can_throw_internal (BB_END (bb))
2137 /* If this is a call edge, verify that this is a call insn. */
2138 && (! (e->flags & EDGE_ABNORMAL_CALL)
2139 || CALL_P (BB_END (bb))))
2145 else if (e->flags & EDGE_ABNORMAL_CALL)
2147 if (CALL_P (BB_END (bb))
2148 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2149 || INTVAL (XEXP (note, 0)) >= 0))
2162 df_set_bb_dirty (bb);
2172 /* We do care only about conditional jumps and simplejumps. */
2173 if (!any_condjump_p (insn)
2174 && !returnjump_p (insn)
2175 && !simplejump_p (insn))
2178 /* Branch probability/prediction notes are defined only for
2179 condjumps. We've possibly turned condjump into simplejump. */
2180 if (simplejump_p (insn))
2182 note = find_reg_note (insn, REG_BR_PROB, NULL);
2184 remove_note (insn, note);
2185 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2186 remove_note (insn, note);
2189 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2191 /* Avoid abnormal flags to leak from computed jumps turned
2192 into simplejumps. */
2194 e->flags &= ~EDGE_ABNORMAL;
2196 /* See if this edge is one we should keep. */
2197 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2198 /* A conditional jump can fall through into the next
2199 block, so we should keep the edge. */
2204 else if (e->dest != EXIT_BLOCK_PTR
2205 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2206 /* If the destination block is the target of the jump,
2212 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2213 /* If the destination block is the exit block, and this
2214 instruction is a return, then keep the edge. */
2219 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2220 /* Keep the edges that correspond to exceptions thrown by
2221 this instruction and rematerialize the EDGE_ABNORMAL
2222 flag we just cleared above. */
2224 e->flags |= EDGE_ABNORMAL;
2229 /* We do not need this edge. */
2230 df_set_bb_dirty (bb);
2235 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2239 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2244 /* Redistribute probabilities. */
2245 if (single_succ_p (bb))
2247 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2248 single_succ_edge (bb)->count = bb->count;
2252 note = find_reg_note (insn, REG_BR_PROB, NULL);
2256 b = BRANCH_EDGE (bb);
2257 f = FALLTHRU_EDGE (bb);
2258 b->probability = INTVAL (XEXP (note, 0));
2259 f->probability = REG_BR_PROB_BASE - b->probability;
2260 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2261 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2266 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2268 /* First, there should not be any EH or ABCALL edges resulting
2269 from non-local gotos and the like. If there were, we shouldn't
2270 have created the sibcall in the first place. Second, there
2271 should of course never have been a fallthru edge. */
2272 gcc_assert (single_succ_p (bb));
2273 gcc_assert (single_succ_edge (bb)->flags
2274 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2279 /* If we don't see a jump insn, we don't know exactly why the block would
2280 have been broken at this point. Look for a simple, non-fallthru edge,
2281 as these are only created by conditional branches. If we find such an
2282 edge we know that there used to be a jump here and can then safely
2283 remove all non-fallthru edges. */
2285 FOR_EACH_EDGE (e, ei, bb->succs)
2286 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2295 /* Remove all but the fake and fallthru edges. The fake edge may be
2296 the only successor for this block in the case of noreturn
2298 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2300 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2302 df_set_bb_dirty (bb);
2310 gcc_assert (single_succ_p (bb));
2312 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2313 single_succ_edge (bb)->count = bb->count;
2316 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2321 /* Search all basic blocks for potentially dead edges and purge them. Return
2322 true if some edge has been eliminated. */
2325 purge_all_dead_edges (void)
2332 bool purged_here = purge_dead_edges (bb);
2334 purged |= purged_here;
2340 /* Same as split_block but update cfg_layout structures. */
2343 cfg_layout_split_block (basic_block bb, void *insnp)
2345 rtx insn = (rtx) insnp;
2346 basic_block new_bb = rtl_split_block (bb, insn);
2348 new_bb->il.rtl->footer = bb->il.rtl->footer;
2349 bb->il.rtl->footer = NULL;
2354 /* Redirect Edge to DEST. */
2356 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2358 basic_block src = e->src;
2361 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2364 if (e->dest == dest)
2367 if (e->src != ENTRY_BLOCK_PTR
2368 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2370 df_set_bb_dirty (src);
2374 if (e->src == ENTRY_BLOCK_PTR
2375 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2378 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2379 e->src->index, dest->index);
2381 df_set_bb_dirty (e->src);
2382 redirect_edge_succ (e, dest);
2386 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2387 in the case the basic block appears to be in sequence. Avoid this
2390 if (e->flags & EDGE_FALLTHRU)
2392 /* Redirect any branch edges unified with the fallthru one. */
2393 if (JUMP_P (BB_END (src))
2394 && label_is_jump_target_p (BB_HEAD (e->dest),
2400 fprintf (dump_file, "Fallthru edge unified with branch "
2401 "%i->%i redirected to %i\n",
2402 e->src->index, e->dest->index, dest->index);
2403 e->flags &= ~EDGE_FALLTHRU;
2404 redirected = redirect_branch_edge (e, dest);
2405 gcc_assert (redirected);
2406 e->flags |= EDGE_FALLTHRU;
2407 df_set_bb_dirty (e->src);
2410 /* In case we are redirecting fallthru edge to the branch edge
2411 of conditional jump, remove it. */
2412 if (EDGE_COUNT (src->succs) == 2)
2414 /* Find the edge that is different from E. */
2415 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2418 && any_condjump_p (BB_END (src))
2419 && onlyjump_p (BB_END (src)))
2420 delete_insn (BB_END (src));
2422 ret = redirect_edge_succ_nodup (e, dest);
2424 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2425 e->src->index, e->dest->index, dest->index);
2428 ret = redirect_branch_edge (e, dest);
2430 /* We don't want simplejumps in the insn stream during cfglayout. */
2431 gcc_assert (!simplejump_p (BB_END (src)));
2433 df_set_bb_dirty (src);
2437 /* Simple wrapper as we always can redirect fallthru edges. */
2439 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2441 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2443 gcc_assert (redirected);
2447 /* Same as delete_basic_block but update cfg_layout structures. */
2450 cfg_layout_delete_block (basic_block bb)
2452 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2454 if (bb->il.rtl->header)
2456 next = BB_HEAD (bb);
2458 NEXT_INSN (prev) = bb->il.rtl->header;
2460 set_first_insn (bb->il.rtl->header);
2461 PREV_INSN (bb->il.rtl->header) = prev;
2462 insn = bb->il.rtl->header;
2463 while (NEXT_INSN (insn))
2464 insn = NEXT_INSN (insn);
2465 NEXT_INSN (insn) = next;
2466 PREV_INSN (next) = insn;
2468 next = NEXT_INSN (BB_END (bb));
2469 if (bb->il.rtl->footer)
2471 insn = bb->il.rtl->footer;
2474 if (BARRIER_P (insn))
2476 if (PREV_INSN (insn))
2477 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2479 bb->il.rtl->footer = NEXT_INSN (insn);
2480 if (NEXT_INSN (insn))
2481 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2485 insn = NEXT_INSN (insn);
2487 if (bb->il.rtl->footer)
2490 NEXT_INSN (insn) = bb->il.rtl->footer;
2491 PREV_INSN (bb->il.rtl->footer) = insn;
2492 while (NEXT_INSN (insn))
2493 insn = NEXT_INSN (insn);
2494 NEXT_INSN (insn) = next;
2496 PREV_INSN (next) = insn;
2498 set_last_insn (insn);
2501 if (bb->next_bb != EXIT_BLOCK_PTR)
2502 to = &bb->next_bb->il.rtl->header;
2504 to = &cfg_layout_function_footer;
2506 rtl_delete_block (bb);
2509 prev = NEXT_INSN (prev);
2511 prev = get_insns ();
2513 next = PREV_INSN (next);
2515 next = get_last_insn ();
2517 if (next && NEXT_INSN (next) != prev)
2519 remaints = unlink_insn_chain (prev, next);
2521 while (NEXT_INSN (insn))
2522 insn = NEXT_INSN (insn);
2523 NEXT_INSN (insn) = *to;
2525 PREV_INSN (*to) = insn;
2530 /* Return true when blocks A and B can be safely merged. */
2533 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2535 /* If we are partitioning hot/cold basic blocks, we don't want to
2536 mess up unconditional or indirect jumps that cross between hot
2539 Basic block partitioning may result in some jumps that appear to
2540 be optimizable (or blocks that appear to be mergeable), but which really
2541 must be left untouched (they are required to make it safely across
2542 partition boundaries). See the comments at the top of
2543 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2545 if (BB_PARTITION (a) != BB_PARTITION (b))
2548 /* There must be exactly one edge in between the blocks. */
2549 return (single_succ_p (a)
2550 && single_succ (a) == b
2551 && single_pred_p (b) == 1
2553 /* Must be simple edge. */
2554 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2555 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2556 /* If the jump insn has side effects, we can't kill the edge.
2557 When not optimizing, try_redirect_by_replacing_jump will
2558 not allow us to redirect an edge by replacing a table jump. */
2559 && (!JUMP_P (BB_END (a))
2560 || ((!optimize || reload_completed)
2561 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2564 /* Merge block A and B. The blocks must be mergeable. */
2567 cfg_layout_merge_blocks (basic_block a, basic_block b)
2569 #ifdef ENABLE_CHECKING
2570 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2574 fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
2576 /* If there was a CODE_LABEL beginning B, delete it. */
2577 if (LABEL_P (BB_HEAD (b)))
2579 delete_insn (BB_HEAD (b));
2582 /* We should have fallthru edge in a, or we can do dummy redirection to get
2584 if (JUMP_P (BB_END (a)))
2585 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2586 gcc_assert (!JUMP_P (BB_END (a)));
2588 /* When not optimizing and the edge is the only place in RTL which holds
2589 some unique locus, emit a nop with that locus in between. */
2590 if (!optimize && EDGE_SUCC (a, 0)->goto_locus)
2592 rtx insn = BB_END (a), end = PREV_INSN (BB_HEAD (a));
2593 int goto_locus = EDGE_SUCC (a, 0)->goto_locus;
2595 while (insn != end && (!INSN_P (insn) || INSN_LOCATOR (insn) == 0))
2596 insn = PREV_INSN (insn);
2597 if (insn != end && locator_eq (INSN_LOCATOR (insn), goto_locus))
2602 end = NEXT_INSN (BB_END (b));
2603 while (insn != end && !INSN_P (insn))
2604 insn = NEXT_INSN (insn);
2605 if (insn != end && INSN_LOCATOR (insn) != 0
2606 && locator_eq (INSN_LOCATOR (insn), goto_locus))
2611 BB_END (a) = emit_insn_after_noloc (gen_nop (), BB_END (a), a);
2612 INSN_LOCATOR (BB_END (a)) = goto_locus;
2616 /* Possible line number notes should appear in between. */
2617 if (b->il.rtl->header)
2619 rtx first = BB_END (a), last;
2621 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2622 delete_insn_chain (NEXT_INSN (first), last, false);
2623 b->il.rtl->header = NULL;
2626 /* In the case basic blocks are not adjacent, move them around. */
2627 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2629 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2631 emit_insn_after_noloc (first, BB_END (a), a);
2632 /* Skip possible DELETED_LABEL insn. */
2633 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2634 first = NEXT_INSN (first);
2635 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2638 /* emit_insn_after_noloc doesn't call df_insn_change_bb.
2639 We need to explicitly call. */
2640 update_bb_for_insn_chain (NEXT_INSN (first),
2644 delete_insn (first);
2646 /* Otherwise just re-associate the instructions. */
2651 update_bb_for_insn_chain (BB_HEAD (b), BB_END (b), a);
2654 /* Skip possible DELETED_LABEL insn. */
2655 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2656 insn = NEXT_INSN (insn);
2657 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2659 BB_END (a) = BB_END (b);
2663 df_bb_delete (b->index);
2665 /* Possible tablejumps and barriers should appear after the block. */
2666 if (b->il.rtl->footer)
2668 if (!a->il.rtl->footer)
2669 a->il.rtl->footer = b->il.rtl->footer;
2672 rtx last = a->il.rtl->footer;
2674 while (NEXT_INSN (last))
2675 last = NEXT_INSN (last);
2676 NEXT_INSN (last) = b->il.rtl->footer;
2677 PREV_INSN (b->il.rtl->footer) = last;
2679 b->il.rtl->footer = NULL;
2683 fprintf (dump_file, "Merged blocks %d and %d.\n",
2684 a->index, b->index);
2690 cfg_layout_split_edge (edge e)
2692 basic_block new_bb =
2693 create_basic_block (e->src != ENTRY_BLOCK_PTR
2694 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2697 if (e->dest == EXIT_BLOCK_PTR)
2698 BB_COPY_PARTITION (new_bb, e->src);
2700 BB_COPY_PARTITION (new_bb, e->dest);
2701 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2702 redirect_edge_and_branch_force (e, new_bb);
2707 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2710 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2714 /* Return 1 if BB ends with a call, possibly followed by some
2715 instructions that must stay with the call, 0 otherwise. */
2718 rtl_block_ends_with_call_p (basic_block bb)
2720 rtx insn = BB_END (bb);
2722 while (!CALL_P (insn)
2723 && insn != BB_HEAD (bb)
2724 && (keep_with_call_p (insn)
2726 insn = PREV_INSN (insn);
2727 return (CALL_P (insn));
2730 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2733 rtl_block_ends_with_condjump_p (const_basic_block bb)
2735 return any_condjump_p (BB_END (bb));
2738 /* Return true if we need to add fake edge to exit.
2739 Helper function for rtl_flow_call_edges_add. */
2742 need_fake_edge_p (const_rtx insn)
2748 && !SIBLING_CALL_P (insn)
2749 && !find_reg_note (insn, REG_NORETURN, NULL)
2750 && !(RTL_CONST_OR_PURE_CALL_P (insn))))
2753 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2754 && MEM_VOLATILE_P (PATTERN (insn)))
2755 || (GET_CODE (PATTERN (insn)) == PARALLEL
2756 && asm_noperands (insn) != -1
2757 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2758 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2761 /* Add fake edges to the function exit for any non constant and non noreturn
2762 calls, volatile inline assembly in the bitmap of blocks specified by
2763 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2766 The goal is to expose cases in which entering a basic block does not imply
2767 that all subsequent instructions must be executed. */
2770 rtl_flow_call_edges_add (sbitmap blocks)
2773 int blocks_split = 0;
2774 int last_bb = last_basic_block;
2775 bool check_last_block = false;
2777 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2781 check_last_block = true;
2783 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2785 /* In the last basic block, before epilogue generation, there will be
2786 a fallthru edge to EXIT. Special care is required if the last insn
2787 of the last basic block is a call because make_edge folds duplicate
2788 edges, which would result in the fallthru edge also being marked
2789 fake, which would result in the fallthru edge being removed by
2790 remove_fake_edges, which would result in an invalid CFG.
2792 Moreover, we can't elide the outgoing fake edge, since the block
2793 profiler needs to take this into account in order to solve the minimal
2794 spanning tree in the case that the call doesn't return.
2796 Handle this by adding a dummy instruction in a new last basic block. */
2797 if (check_last_block)
2799 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2800 rtx insn = BB_END (bb);
2802 /* Back up past insns that must be kept in the same block as a call. */
2803 while (insn != BB_HEAD (bb)
2804 && keep_with_call_p (insn))
2805 insn = PREV_INSN (insn);
2807 if (need_fake_edge_p (insn))
2811 e = find_edge (bb, EXIT_BLOCK_PTR);
2814 insert_insn_on_edge (gen_use (const0_rtx), e);
2815 commit_edge_insertions ();
2820 /* Now add fake edges to the function exit for any non constant
2821 calls since there is no way that we can determine if they will
2824 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
2826 basic_block bb = BASIC_BLOCK (i);
2833 if (blocks && !TEST_BIT (blocks, i))
2836 for (insn = BB_END (bb); ; insn = prev_insn)
2838 prev_insn = PREV_INSN (insn);
2839 if (need_fake_edge_p (insn))
2842 rtx split_at_insn = insn;
2844 /* Don't split the block between a call and an insn that should
2845 remain in the same block as the call. */
2847 while (split_at_insn != BB_END (bb)
2848 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2849 split_at_insn = NEXT_INSN (split_at_insn);
2851 /* The handling above of the final block before the epilogue
2852 should be enough to verify that there is no edge to the exit
2853 block in CFG already. Calling make_edge in such case would
2854 cause us to mark that edge as fake and remove it later. */
2856 #ifdef ENABLE_CHECKING
2857 if (split_at_insn == BB_END (bb))
2859 e = find_edge (bb, EXIT_BLOCK_PTR);
2860 gcc_assert (e == NULL);
2864 /* Note that the following may create a new basic block
2865 and renumber the existing basic blocks. */
2866 if (split_at_insn != BB_END (bb))
2868 e = split_block (bb, split_at_insn);
2873 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2876 if (insn == BB_HEAD (bb))
2882 verify_flow_info ();
2884 return blocks_split;
2887 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2888 the conditional branch target, SECOND_HEAD should be the fall-thru
2889 there is no need to handle this here the loop versioning code handles
2890 this. the reason for SECON_HEAD is that it is needed for condition
2891 in trees, and this should be of the same type since it is a hook. */
2893 rtl_lv_add_condition_to_bb (basic_block first_head ,
2894 basic_block second_head ATTRIBUTE_UNUSED,
2895 basic_block cond_bb, void *comp_rtx)
2897 rtx label, seq, jump;
2898 rtx op0 = XEXP ((rtx)comp_rtx, 0);
2899 rtx op1 = XEXP ((rtx)comp_rtx, 1);
2900 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
2901 enum machine_mode mode;
2904 label = block_label (first_head);
2905 mode = GET_MODE (op0);
2906 if (mode == VOIDmode)
2907 mode = GET_MODE (op1);
2910 op0 = force_operand (op0, NULL_RTX);
2911 op1 = force_operand (op1, NULL_RTX);
2912 do_compare_rtx_and_jump (op0, op1, comp, 0,
2913 mode, NULL_RTX, NULL_RTX, label);
2914 jump = get_last_insn ();
2915 JUMP_LABEL (jump) = label;
2916 LABEL_NUSES (label)++;
2920 /* Add the new cond , in the new head. */
2921 emit_insn_after(seq, BB_END(cond_bb));
2925 /* Given a block B with unconditional branch at its end, get the
2926 store the return the branch edge and the fall-thru edge in
2927 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
2929 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
2930 edge *fallthru_edge)
2932 edge e = EDGE_SUCC (b, 0);
2934 if (e->flags & EDGE_FALLTHRU)
2937 *branch_edge = EDGE_SUCC (b, 1);
2942 *fallthru_edge = EDGE_SUCC (b, 1);
2947 init_rtl_bb_info (basic_block bb)
2949 gcc_assert (!bb->il.rtl);
2950 bb->il.rtl = GGC_CNEW (struct rtl_bb_info);
2954 /* Add EXPR to the end of basic block BB. */
2957 insert_insn_end_bb_new (rtx pat, basic_block bb)
2959 rtx insn = BB_END (bb);
2963 while (NEXT_INSN (pat_end) != NULL_RTX)
2964 pat_end = NEXT_INSN (pat_end);
2966 /* If the last insn is a jump, insert EXPR in front [taking care to
2967 handle cc0, etc. properly]. Similarly we need to care trapping
2968 instructions in presence of non-call exceptions. */
2971 || (NONJUMP_INSN_P (insn)
2972 && (!single_succ_p (bb)
2973 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
2978 /* If this is a jump table, then we can't insert stuff here. Since
2979 we know the previous real insn must be the tablejump, we insert
2980 the new instruction just before the tablejump. */
2981 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
2982 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
2983 insn = prev_real_insn (insn);
2986 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
2987 if cc0 isn't set. */
2988 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
2990 insn = XEXP (note, 0);
2993 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
2994 if (maybe_cc0_setter
2995 && INSN_P (maybe_cc0_setter)
2996 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
2997 insn = maybe_cc0_setter;
3000 /* FIXME: What if something in cc0/jump uses value set in new
3002 new_insn = emit_insn_before_noloc (pat, insn, bb);
3005 /* Likewise if the last insn is a call, as will happen in the presence
3006 of exception handling. */
3007 else if (CALL_P (insn)
3008 && (!single_succ_p (bb)
3009 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
3011 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
3012 we search backward and place the instructions before the first
3013 parameter is loaded. Do this for everyone for consistency and a
3014 presumption that we'll get better code elsewhere as well. */
3016 /* Since different machines initialize their parameter registers
3017 in different orders, assume nothing. Collect the set of all
3018 parameter registers. */
3019 insn = find_first_parameter_load (insn, BB_HEAD (bb));
3021 /* If we found all the parameter loads, then we want to insert
3022 before the first parameter load.
3024 If we did not find all the parameter loads, then we might have
3025 stopped on the head of the block, which could be a CODE_LABEL.
3026 If we inserted before the CODE_LABEL, then we would be putting
3027 the insn in the wrong basic block. In that case, put the insn
3028 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
3029 while (LABEL_P (insn)
3030 || NOTE_INSN_BASIC_BLOCK_P (insn))
3031 insn = NEXT_INSN (insn);
3033 new_insn = emit_insn_before_noloc (pat, insn, bb);
3036 new_insn = emit_insn_after_noloc (pat, insn, bb);
3041 /* Returns true if it is possible to remove edge E by redirecting
3042 it to the destination of the other edge from E->src. */
3045 rtl_can_remove_branch_p (const_edge e)
3047 const_basic_block src = e->src;
3048 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3049 const_rtx insn = BB_END (src), set;
3051 /* The conditions are taken from try_redirect_by_replacing_jump. */
3052 if (target == EXIT_BLOCK_PTR)
3055 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3058 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3059 || BB_PARTITION (src) != BB_PARTITION (target))
3062 if (!onlyjump_p (insn)
3063 || tablejump_p (insn, NULL, NULL))
3066 set = single_set (insn);
3067 if (!set || side_effects_p (set))
3073 /* Implementation of CFG manipulation for linearized RTL. */
3074 struct cfg_hooks rtl_cfg_hooks = {
3076 rtl_verify_flow_info,
3078 rtl_create_basic_block,
3079 rtl_redirect_edge_and_branch,
3080 rtl_redirect_edge_and_branch_force,
3081 rtl_can_remove_branch_p,
3084 rtl_move_block_after,
3085 rtl_can_merge_blocks, /* can_merge_blocks_p */
3089 NULL, /* can_duplicate_block_p */
3090 NULL, /* duplicate_block */
3092 rtl_make_forwarder_block,
3093 rtl_tidy_fallthru_edge,
3094 rtl_block_ends_with_call_p,
3095 rtl_block_ends_with_condjump_p,
3096 rtl_flow_call_edges_add,
3097 NULL, /* execute_on_growing_pred */
3098 NULL, /* execute_on_shrinking_pred */
3099 NULL, /* duplicate loop for trees */
3100 NULL, /* lv_add_condition_to_bb */
3101 NULL, /* lv_adjust_loop_header_phi*/
3102 NULL, /* extract_cond_bb_edges */
3103 NULL /* flush_pending_stmts */
3106 /* Implementation of CFG manipulation for cfg layout RTL, where
3107 basic block connected via fallthru edges does not have to be adjacent.
3108 This representation will hopefully become the default one in future
3109 version of the compiler. */
3111 /* We do not want to declare these functions in a header file, since they
3112 should only be used through the cfghooks interface, and we do not want to
3113 move them here since it would require also moving quite a lot of related
3114 code. They are in cfglayout.c. */
3115 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3116 extern basic_block cfg_layout_duplicate_bb (basic_block);
3118 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3120 rtl_verify_flow_info_1,
3122 cfg_layout_create_basic_block,
3123 cfg_layout_redirect_edge_and_branch,
3124 cfg_layout_redirect_edge_and_branch_force,
3125 rtl_can_remove_branch_p,
3126 cfg_layout_delete_block,
3127 cfg_layout_split_block,
3128 rtl_move_block_after,
3129 cfg_layout_can_merge_blocks_p,
3130 cfg_layout_merge_blocks,
3133 cfg_layout_can_duplicate_bb_p,
3134 cfg_layout_duplicate_bb,
3135 cfg_layout_split_edge,
3136 rtl_make_forwarder_block,
3138 rtl_block_ends_with_call_p,
3139 rtl_block_ends_with_condjump_p,
3140 rtl_flow_call_edges_add,
3141 NULL, /* execute_on_growing_pred */
3142 NULL, /* execute_on_shrinking_pred */
3143 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3144 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3145 NULL, /* lv_adjust_loop_header_phi*/
3146 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3147 NULL /* flush_pending_stmts */