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
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);
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 && LABEL_P (JUMP_LABEL (insn)))
144 LABEL_NUSES (JUMP_LABEL (insn))--;
146 /* Also if deleting an insn that references a label. */
149 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
150 && LABEL_P (XEXP (note, 0)))
152 LABEL_NUSES (XEXP (note, 0))--;
153 remove_note (insn, note);
158 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
159 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
161 rtx pat = PATTERN (insn);
162 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
163 int len = XVECLEN (pat, diff_vec_p);
166 for (i = 0; i < len; i++)
168 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
170 /* When deleting code in bulk (e.g. removing many unreachable
171 blocks) we can delete a label that's a target of the vector
172 before deleting the vector itself. */
174 LABEL_NUSES (label)--;
181 /* Like delete_insn but also purge dead edges from BB. */
183 delete_insn_and_edges (rtx insn)
189 && BLOCK_FOR_INSN (insn)
190 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
192 x = delete_insn (insn);
194 purge_dead_edges (BLOCK_FOR_INSN (insn));
198 /* Unlink a chain of insns between START and FINISH, leaving notes
199 that must be paired. If CLEAR_BB is true, we set bb field for
200 insns that cannot be removed to NULL. */
203 delete_insn_chain (rtx start, rtx finish, bool clear_bb)
207 /* Unchain the insns one by one. It would be quicker to delete all of these
208 with a single unchaining, rather than one at a time, but we need to keep
212 next = NEXT_INSN (start);
213 if (NOTE_P (start) && !can_delete_note_p (start))
216 next = delete_insn (start);
218 if (clear_bb && !INSN_DELETED_P (start))
219 set_block_for_insn (start, NULL);
227 /* Create a new basic block consisting of the instructions between HEAD and END
228 inclusive. This function is designed to allow fast BB construction - reuses
229 the note and basic block struct in BB_NOTE, if any and do not grow
230 BASIC_BLOCK chain and should be used directly only by CFG construction code.
231 END can be NULL in to create new empty basic block before HEAD. Both END
232 and HEAD can be NULL to create basic block at the end of INSN chain.
233 AFTER is the basic block we should be put after. */
236 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
241 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
244 /* If we found an existing note, thread it back onto the chain. */
252 after = PREV_INSN (head);
256 if (after != bb_note && NEXT_INSN (after) != bb_note)
257 reorder_insns_nobb (bb_note, bb_note, after);
261 /* Otherwise we must create a note and a basic block structure. */
265 init_rtl_bb_info (bb);
268 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
269 else if (LABEL_P (head) && end)
271 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
277 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
283 NOTE_BASIC_BLOCK (bb_note) = bb;
286 /* Always include the bb note in the block. */
287 if (NEXT_INSN (end) == bb_note)
292 bb->index = last_basic_block++;
293 bb->flags = BB_NEW | BB_RTL;
294 link_block (bb, after);
295 SET_BASIC_BLOCK (bb->index, bb);
296 df_bb_refs_record (bb->index, false);
297 update_bb_for_insn (bb);
298 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
300 /* Tag the block so that we know it has been used when considering
301 other basic block notes. */
307 /* Create new basic block consisting of instructions in between HEAD and END
308 and place it to the BB chain after block AFTER. END can be NULL in to
309 create new empty basic block before HEAD. Both END and HEAD can be NULL to
310 create basic block at the end of INSN chain. */
313 rtl_create_basic_block (void *headp, void *endp, basic_block after)
315 rtx head = (rtx) headp, end = (rtx) endp;
318 /* Grow the basic block array if needed. */
319 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info))
321 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
322 VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size);
327 bb = create_basic_block_structure (head, end, NULL, after);
333 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
335 basic_block newbb = rtl_create_basic_block (head, end, after);
340 /* Delete the insns in a (non-live) block. We physically delete every
341 non-deleted-note insn, and update the flow graph appropriately.
343 Return nonzero if we deleted an exception handler. */
345 /* ??? Preserving all such notes strikes me as wrong. It would be nice
346 to post-process the stream to remove empty blocks, loops, ranges, etc. */
349 rtl_delete_block (basic_block b)
353 /* If the head of this block is a CODE_LABEL, then it might be the
354 label for an exception handler which can't be reached. We need
355 to remove the label from the exception_handler_label list. */
358 maybe_remove_eh_handler (insn);
360 end = get_last_bb_insn (b);
362 /* Selectively delete the entire chain. */
364 delete_insn_chain (insn, end, true);
368 fprintf (dump_file, "deleting block %d\n", b->index);
369 df_bb_delete (b->index);
372 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
375 compute_bb_for_insn (void)
381 rtx end = BB_END (bb);
384 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
386 BLOCK_FOR_INSN (insn) = bb;
393 /* Release the basic_block_for_insn array. */
396 free_bb_for_insn (void)
399 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
400 if (!BARRIER_P (insn))
401 BLOCK_FOR_INSN (insn) = NULL;
405 struct tree_opt_pass pass_free_cfg =
409 free_bb_for_insn, /* execute */
412 0, /* static_pass_number */
414 0, /* properties_required */
415 0, /* properties_provided */
416 PROP_cfg, /* properties_destroyed */
417 0, /* todo_flags_start */
418 0, /* todo_flags_finish */
422 /* Return RTX to emit after when we want to emit code on the entry of function. */
424 entry_of_function (void)
426 return (n_basic_blocks > NUM_FIXED_BLOCKS ?
427 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
430 /* Emit INSN at the entry point of the function, ensuring that it is only
431 executed once per function. */
433 emit_insn_at_entry (rtx insn)
435 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs);
436 edge e = ei_safe_edge (ei);
437 gcc_assert (e->flags & EDGE_FALLTHRU);
439 insert_insn_on_edge (insn, e);
440 commit_edge_insertions ();
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 (!BARRIER_P (insn))
454 set_block_for_insn (insn, bb);
455 df_insn_change_bb (insn);
457 if (insn == BB_END (bb))
462 /* Return the INSN immediately following the NOTE_INSN_BASIC_BLOCK
463 note associated with the BLOCK. */
466 first_insn_after_basic_block_note (basic_block block)
470 /* Get the first instruction in the block. */
471 insn = BB_HEAD (block);
473 if (insn == NULL_RTX)
476 insn = NEXT_INSN (insn);
477 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
479 return NEXT_INSN (insn);
482 /* Creates a new basic block just after basic block B by splitting
483 everything after specified instruction I. */
486 rtl_split_block (basic_block bb, void *insnp)
489 rtx insn = (rtx) insnp;
495 insn = first_insn_after_basic_block_note (bb);
498 insn = PREV_INSN (insn);
500 insn = get_last_insn ();
503 /* We probably should check type of the insn so that we do not create
504 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
506 if (insn == BB_END (bb))
507 emit_note_after (NOTE_INSN_DELETED, insn);
509 /* Create the new basic block. */
510 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
511 BB_COPY_PARTITION (new_bb, bb);
514 /* Redirect the outgoing edges. */
515 new_bb->succs = bb->succs;
517 FOR_EACH_EDGE (e, ei, new_bb->succs)
520 /* The new block starts off being dirty. */
521 df_set_bb_dirty (bb);
525 /* Blocks A and B are to be merged into a single block A. The insns
526 are already contiguous. */
529 rtl_merge_blocks (basic_block a, basic_block b)
531 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
532 rtx del_first = NULL_RTX, del_last = NULL_RTX;
536 fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
538 /* If there was a CODE_LABEL beginning B, delete it. */
539 if (LABEL_P (b_head))
541 /* This might have been an EH label that no longer has incoming
542 EH edges. Update data structures to match. */
543 maybe_remove_eh_handler (b_head);
545 /* Detect basic blocks with nothing but a label. This can happen
546 in particular at the end of a function. */
550 del_first = del_last = b_head;
551 b_head = NEXT_INSN (b_head);
554 /* Delete the basic block note and handle blocks containing just that
556 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
564 b_head = NEXT_INSN (b_head);
567 /* If there was a jump out of A, delete it. */
572 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
574 || NOTE_INSN_BASIC_BLOCK_P (prev)
575 || prev == BB_HEAD (a))
581 /* If this was a conditional jump, we need to also delete
582 the insn that set cc0. */
583 if (only_sets_cc0_p (prev))
587 prev = prev_nonnote_insn (prev);
594 a_end = PREV_INSN (del_first);
596 else if (BARRIER_P (NEXT_INSN (a_end)))
597 del_first = NEXT_INSN (a_end);
599 /* Delete everything marked above as well as crap that might be
600 hanging out between the two blocks. */
602 delete_insn_chain (del_first, del_last, true);
604 /* Reassociate the insns of B with A. */
609 for (x = a_end; x != b_end; x = NEXT_INSN (x))
611 set_block_for_insn (x, a);
612 df_insn_change_bb (x);
615 set_block_for_insn (b_end, a);
616 df_insn_change_bb (b_end);
621 df_bb_delete (b->index);
626 /* Return true when block A and B can be merged. */
629 rtl_can_merge_blocks (basic_block a, basic_block b)
631 /* If we are partitioning hot/cold basic blocks, we don't want to
632 mess up unconditional or indirect jumps that cross between hot
635 Basic block partitioning may result in some jumps that appear to
636 be optimizable (or blocks that appear to be mergeable), but which really
637 must be left untouched (they are required to make it safely across
638 partition boundaries). See the comments at the top of
639 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
641 if (BB_PARTITION (a) != BB_PARTITION (b))
644 /* There must be exactly one edge in between the blocks. */
645 return (single_succ_p (a)
646 && single_succ (a) == b
649 /* Must be simple edge. */
650 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
652 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
653 /* If the jump insn has side effects,
654 we can't kill the edge. */
655 && (!JUMP_P (BB_END (a))
657 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
660 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
664 block_label (basic_block block)
666 if (block == EXIT_BLOCK_PTR)
669 if (!LABEL_P (BB_HEAD (block)))
671 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
674 return BB_HEAD (block);
677 /* Attempt to perform edge redirection by replacing possibly complex jump
678 instruction by unconditional jump or removing jump completely. This can
679 apply only if all edges now point to the same block. The parameters and
680 return values are equivalent to redirect_edge_and_branch. */
683 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
685 basic_block src = e->src;
686 rtx insn = BB_END (src), kill_from;
690 /* If we are partitioning hot/cold basic blocks, we don't want to
691 mess up unconditional or indirect jumps that cross between hot
694 Basic block partitioning may result in some jumps that appear to
695 be optimizable (or blocks that appear to be mergeable), but which really
696 must be left untouched (they are required to make it safely across
697 partition boundaries). See the comments at the top of
698 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
700 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
701 || BB_PARTITION (src) != BB_PARTITION (target))
704 /* We can replace or remove a complex jump only when we have exactly
705 two edges. Also, if we have exactly one outgoing edge, we can
707 if (EDGE_COUNT (src->succs) >= 3
708 /* Verify that all targets will be TARGET. Specifically, the
709 edge that is not E must also go to TARGET. */
710 || (EDGE_COUNT (src->succs) == 2
711 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
714 if (!onlyjump_p (insn))
716 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
719 /* Avoid removing branch with side effects. */
720 set = single_set (insn);
721 if (!set || side_effects_p (set))
724 /* In case we zap a conditional jump, we'll need to kill
725 the cc0 setter too. */
728 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
729 && only_sets_cc0_p (PREV_INSN (insn)))
730 kill_from = PREV_INSN (insn);
733 /* See if we can create the fallthru edge. */
734 if (in_cfglayout || can_fallthru (src, target))
737 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
740 /* Selectively unlink whole insn chain. */
743 rtx insn = src->il.rtl->footer;
745 delete_insn_chain (kill_from, BB_END (src), false);
747 /* Remove barriers but keep jumptables. */
750 if (BARRIER_P (insn))
752 if (PREV_INSN (insn))
753 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
755 src->il.rtl->footer = NEXT_INSN (insn);
756 if (NEXT_INSN (insn))
757 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
761 insn = NEXT_INSN (insn);
765 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
769 /* If this already is simplejump, redirect it. */
770 else if (simplejump_p (insn))
772 if (e->dest == target)
775 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
776 INSN_UID (insn), e->dest->index, target->index);
777 if (!redirect_jump (insn, block_label (target), 0))
779 gcc_assert (target == EXIT_BLOCK_PTR);
784 /* Cannot do anything for target exit block. */
785 else if (target == EXIT_BLOCK_PTR)
788 /* Or replace possibly complicated jump insn by simple jump insn. */
791 rtx target_label = block_label (target);
792 rtx barrier, label, table;
794 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
795 JUMP_LABEL (BB_END (src)) = target_label;
796 LABEL_NUSES (target_label)++;
798 fprintf (dump_file, "Replacing insn %i by jump %i\n",
799 INSN_UID (insn), INSN_UID (BB_END (src)));
802 delete_insn_chain (kill_from, insn, false);
804 /* Recognize a tablejump that we are converting to a
805 simple jump and remove its associated CODE_LABEL
806 and ADDR_VEC or ADDR_DIFF_VEC. */
807 if (tablejump_p (insn, &label, &table))
808 delete_insn_chain (label, table, false);
810 barrier = next_nonnote_insn (BB_END (src));
811 if (!barrier || !BARRIER_P (barrier))
812 emit_barrier_after (BB_END (src));
815 if (barrier != NEXT_INSN (BB_END (src)))
817 /* Move the jump before barrier so that the notes
818 which originally were or were created before jump table are
819 inside the basic block. */
820 rtx new_insn = BB_END (src);
823 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
824 tmp = NEXT_INSN (tmp))
826 set_block_for_insn (tmp, src);
827 df_insn_change_bb (tmp);
830 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
831 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
833 NEXT_INSN (new_insn) = barrier;
834 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
836 PREV_INSN (new_insn) = PREV_INSN (barrier);
837 PREV_INSN (barrier) = new_insn;
842 /* Keep only one edge out and set proper flags. */
843 if (!single_succ_p (src))
845 gcc_assert (single_succ_p (src));
847 e = single_succ_edge (src);
849 e->flags = EDGE_FALLTHRU;
853 e->probability = REG_BR_PROB_BASE;
854 e->count = src->count;
856 if (e->dest != target)
857 redirect_edge_succ (e, target);
861 /* Redirect edge representing branch of (un)conditional jump or tablejump,
864 redirect_branch_edge (edge e, basic_block target)
867 rtx old_label = BB_HEAD (e->dest);
868 basic_block src = e->src;
869 rtx insn = BB_END (src);
871 /* We can only redirect non-fallthru edges of jump insn. */
872 if (e->flags & EDGE_FALLTHRU)
874 else if (!JUMP_P (insn))
877 /* Recognize a tablejump and adjust all matching cases. */
878 if (tablejump_p (insn, NULL, &tmp))
882 rtx new_label = block_label (target);
884 if (target == EXIT_BLOCK_PTR)
886 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
887 vec = XVEC (PATTERN (tmp), 0);
889 vec = XVEC (PATTERN (tmp), 1);
891 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
892 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
894 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
895 --LABEL_NUSES (old_label);
896 ++LABEL_NUSES (new_label);
899 /* Handle casesi dispatch insns. */
900 if ((tmp = single_set (insn)) != NULL
901 && SET_DEST (tmp) == pc_rtx
902 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
903 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
904 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
906 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
908 --LABEL_NUSES (old_label);
909 ++LABEL_NUSES (new_label);
914 /* ?? We may play the games with moving the named labels from
915 one basic block to the other in case only one computed_jump is
917 if (computed_jump_p (insn)
918 /* A return instruction can't be redirected. */
919 || returnjump_p (insn))
922 /* If the insn doesn't go where we think, we're confused. */
923 gcc_assert (JUMP_LABEL (insn) == old_label);
925 /* If the substitution doesn't succeed, die. This can happen
926 if the back end emitted unrecognizable instructions or if
927 target is exit block on some arches. */
928 if (!redirect_jump (insn, block_label (target), 0))
930 gcc_assert (target == EXIT_BLOCK_PTR);
936 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
937 e->src->index, e->dest->index, target->index);
939 if (e->dest != target)
940 e = redirect_edge_succ_nodup (e, target);
945 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
946 expense of adding new instructions or reordering basic blocks.
948 Function can be also called with edge destination equivalent to the TARGET.
949 Then it should try the simplifications and do nothing if none is possible.
951 Return edge representing the branch if transformation succeeded. Return NULL
953 We still return NULL in case E already destinated TARGET and we didn't
954 managed to simplify instruction stream. */
957 rtl_redirect_edge_and_branch (edge e, basic_block target)
960 basic_block src = e->src;
962 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
965 if (e->dest == target)
968 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
970 df_set_bb_dirty (src);
974 ret = redirect_branch_edge (e, target);
978 df_set_bb_dirty (src);
982 /* Like force_nonfallthru below, but additionally performs redirection
983 Used by redirect_edge_and_branch_force. */
986 force_nonfallthru_and_redirect (edge e, basic_block target)
988 basic_block jump_block, new_bb = NULL, src = e->src;
991 int abnormal_edge_flags = 0;
993 /* In the case the last instruction is conditional jump to the next
994 instruction, first redirect the jump itself and then continue
995 by creating a basic block afterwards to redirect fallthru edge. */
996 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
997 && any_condjump_p (BB_END (e->src))
998 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1001 edge b = unchecked_make_edge (e->src, target, 0);
1004 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1005 gcc_assert (redirected);
1007 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1010 int prob = INTVAL (XEXP (note, 0));
1012 b->probability = prob;
1013 b->count = e->count * prob / REG_BR_PROB_BASE;
1014 e->probability -= e->probability;
1015 e->count -= b->count;
1016 if (e->probability < 0)
1023 if (e->flags & EDGE_ABNORMAL)
1025 /* Irritating special case - fallthru edge to the same block as abnormal
1027 We can't redirect abnormal edge, but we still can split the fallthru
1028 one and create separate abnormal edge to original destination.
1029 This allows bb-reorder to make such edge non-fallthru. */
1030 gcc_assert (e->dest == target);
1031 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1032 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1036 gcc_assert (e->flags & EDGE_FALLTHRU);
1037 if (e->src == ENTRY_BLOCK_PTR)
1039 /* We can't redirect the entry block. Create an empty block
1040 at the start of the function which we use to add the new
1046 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1048 /* Change the existing edge's source to be the new block, and add
1049 a new edge from the entry block to the new block. */
1051 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1055 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1065 VEC_safe_push (edge, gc, bb->succs, e);
1066 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1070 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1072 /* Create the new structures. */
1074 /* If the old block ended with a tablejump, skip its table
1075 by searching forward from there. Otherwise start searching
1076 forward from the last instruction of the old block. */
1077 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1078 note = BB_END (e->src);
1079 note = NEXT_INSN (note);
1081 jump_block = create_basic_block (note, NULL, e->src);
1082 jump_block->count = e->count;
1083 jump_block->frequency = EDGE_FREQUENCY (e);
1084 jump_block->loop_depth = target->loop_depth;
1086 /* Make sure new block ends up in correct hot/cold section. */
1088 BB_COPY_PARTITION (jump_block, e->src);
1089 if (flag_reorder_blocks_and_partition
1090 && targetm.have_named_sections
1091 && JUMP_P (BB_END (jump_block))
1092 && !any_condjump_p (BB_END (jump_block))
1093 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1094 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP,
1101 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1102 new_edge->probability = e->probability;
1103 new_edge->count = e->count;
1105 /* Redirect old edge. */
1106 redirect_edge_pred (e, jump_block);
1107 e->probability = REG_BR_PROB_BASE;
1109 new_bb = jump_block;
1112 jump_block = e->src;
1114 e->flags &= ~EDGE_FALLTHRU;
1115 if (target == EXIT_BLOCK_PTR)
1118 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1125 rtx label = block_label (target);
1126 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1127 JUMP_LABEL (BB_END (jump_block)) = label;
1128 LABEL_NUSES (label)++;
1131 emit_barrier_after (BB_END (jump_block));
1132 redirect_edge_succ_nodup (e, target);
1134 if (abnormal_edge_flags)
1135 make_edge (src, target, abnormal_edge_flags);
1137 df_mark_solutions_dirty ();
1141 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1142 (and possibly create new basic block) to make edge non-fallthru.
1143 Return newly created BB or NULL if none. */
1146 force_nonfallthru (edge e)
1148 return force_nonfallthru_and_redirect (e, e->dest);
1151 /* Redirect edge even at the expense of creating new jump insn or
1152 basic block. Return new basic block if created, NULL otherwise.
1153 Conversion must be possible. */
1156 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1158 if (redirect_edge_and_branch (e, target)
1159 || e->dest == target)
1162 /* In case the edge redirection failed, try to force it to be non-fallthru
1163 and redirect newly created simplejump. */
1164 df_set_bb_dirty (e->src);
1165 return force_nonfallthru_and_redirect (e, target);
1168 /* The given edge should potentially be a fallthru edge. If that is in
1169 fact true, delete the jump and barriers that are in the way. */
1172 rtl_tidy_fallthru_edge (edge e)
1175 basic_block b = e->src, c = b->next_bb;
1177 /* ??? In a late-running flow pass, other folks may have deleted basic
1178 blocks by nopping out blocks, leaving multiple BARRIERs between here
1179 and the target label. They ought to be chastised and fixed.
1181 We can also wind up with a sequence of undeletable labels between
1182 one block and the next.
1184 So search through a sequence of barriers, labels, and notes for
1185 the head of block C and assert that we really do fall through. */
1187 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1191 /* Remove what will soon cease being the jump insn from the source block.
1192 If block B consisted only of this single jump, turn it into a deleted
1197 && (any_uncondjump_p (q)
1198 || single_succ_p (b)))
1201 /* If this was a conditional jump, we need to also delete
1202 the insn that set cc0. */
1203 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1210 /* Selectively unlink the sequence. */
1211 if (q != PREV_INSN (BB_HEAD (c)))
1212 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)), false);
1214 e->flags |= EDGE_FALLTHRU;
1217 /* Should move basic block BB after basic block AFTER. NIY. */
1220 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1221 basic_block after ATTRIBUTE_UNUSED)
1226 /* Split a (typically critical) edge. Return the new block.
1227 The edge must not be abnormal.
1229 ??? The code generally expects to be called on critical edges.
1230 The case of a block ending in an unconditional jump to a
1231 block with multiple predecessors is not handled optimally. */
1234 rtl_split_edge (edge edge_in)
1239 /* Abnormal edges cannot be split. */
1240 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1242 /* We are going to place the new block in front of edge destination.
1243 Avoid existence of fallthru predecessors. */
1244 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1249 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1250 if (e->flags & EDGE_FALLTHRU)
1254 force_nonfallthru (e);
1257 /* Create the basic block note. */
1258 if (edge_in->dest != EXIT_BLOCK_PTR)
1259 before = BB_HEAD (edge_in->dest);
1263 /* If this is a fall through edge to the exit block, the blocks might be
1264 not adjacent, and the right place is the after the source. */
1265 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1267 before = NEXT_INSN (BB_END (edge_in->src));
1268 bb = create_basic_block (before, NULL, edge_in->src);
1269 BB_COPY_PARTITION (bb, edge_in->src);
1273 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1274 /* ??? Why not edge_in->dest->prev_bb here? */
1275 BB_COPY_PARTITION (bb, edge_in->dest);
1278 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1280 /* For non-fallthru edges, we must adjust the predecessor's
1281 jump instruction to target our new block. */
1282 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1284 edge redirected = redirect_edge_and_branch (edge_in, bb);
1285 gcc_assert (redirected);
1288 redirect_edge_succ (edge_in, bb);
1293 /* Queue instructions for insertion on an edge between two basic blocks.
1294 The new instructions and basic blocks (if any) will not appear in the
1295 CFG until commit_edge_insertions is called. */
1298 insert_insn_on_edge (rtx pattern, edge e)
1300 /* We cannot insert instructions on an abnormal critical edge.
1301 It will be easier to find the culprit if we die now. */
1302 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1304 if (e->insns.r == NULL_RTX)
1307 push_to_sequence (e->insns.r);
1309 emit_insn (pattern);
1311 e->insns.r = get_insns ();
1315 /* Update the CFG for the instructions queued on edge E. */
1318 commit_one_edge_insertion (edge e)
1320 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1321 basic_block bb = NULL;
1323 /* Pull the insns off the edge now since the edge might go away. */
1325 e->insns.r = NULL_RTX;
1327 if (!before && !after)
1329 /* Figure out where to put these things. If the destination has
1330 one predecessor, insert there. Except for the exit block. */
1331 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1335 /* Get the location correct wrt a code label, and "nice" wrt
1336 a basic block note, and before everything else. */
1339 tmp = NEXT_INSN (tmp);
1340 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1341 tmp = NEXT_INSN (tmp);
1342 if (tmp == BB_HEAD (bb))
1345 after = PREV_INSN (tmp);
1347 after = get_last_insn ();
1350 /* If the source has one successor and the edge is not abnormal,
1351 insert there. Except for the entry block. */
1352 else if ((e->flags & EDGE_ABNORMAL) == 0
1353 && single_succ_p (e->src)
1354 && e->src != ENTRY_BLOCK_PTR)
1358 /* It is possible to have a non-simple jump here. Consider a target
1359 where some forms of unconditional jumps clobber a register. This
1360 happens on the fr30 for example.
1362 We know this block has a single successor, so we can just emit
1363 the queued insns before the jump. */
1364 if (JUMP_P (BB_END (bb)))
1365 before = BB_END (bb);
1368 /* We'd better be fallthru, or we've lost track of
1370 gcc_assert (e->flags & EDGE_FALLTHRU);
1372 after = BB_END (bb);
1375 /* Otherwise we must split the edge. */
1378 bb = split_edge (e);
1379 after = BB_END (bb);
1381 if (flag_reorder_blocks_and_partition
1382 && targetm.have_named_sections
1383 && e->src != ENTRY_BLOCK_PTR
1384 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1385 && !(e->flags & EDGE_CROSSING))
1387 rtx bb_note, cur_insn;
1390 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1391 cur_insn = NEXT_INSN (cur_insn))
1392 if (NOTE_INSN_BASIC_BLOCK_P (cur_insn))
1398 if (JUMP_P (BB_END (bb))
1399 && !any_condjump_p (BB_END (bb))
1400 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1401 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1402 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1407 /* Now that we've found the spot, do the insertion. */
1411 emit_insn_before_noloc (insns, before, bb);
1412 last = prev_nonnote_insn (before);
1415 last = emit_insn_after_noloc (insns, after, bb);
1417 if (returnjump_p (last))
1419 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1420 This is not currently a problem because this only happens
1421 for the (single) epilogue, which already has a fallthru edge
1424 e = single_succ_edge (bb);
1425 gcc_assert (e->dest == EXIT_BLOCK_PTR
1426 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1428 e->flags &= ~EDGE_FALLTHRU;
1429 emit_barrier_after (last);
1432 delete_insn (before);
1435 gcc_assert (!JUMP_P (last));
1437 /* Mark the basic block for find_many_sub_basic_blocks. */
1438 if (current_ir_type () != IR_RTL_CFGLAYOUT)
1442 /* Update the CFG for all queued instructions. */
1445 commit_edge_insertions (void)
1449 bool changed = false;
1451 #ifdef ENABLE_CHECKING
1452 verify_flow_info ();
1455 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1460 FOR_EACH_EDGE (e, ei, bb->succs)
1464 commit_one_edge_insertion (e);
1471 /* In the old rtl CFG API, it was OK to insert control flow on an
1472 edge, apparently? In cfglayout mode, this will *not* work, and
1473 the caller is responsible for making sure that control flow is
1474 valid at all times. */
1475 if (current_ir_type () == IR_RTL_CFGLAYOUT)
1478 blocks = sbitmap_alloc (last_basic_block);
1479 sbitmap_zero (blocks);
1483 SET_BIT (blocks, bb->index);
1484 /* Check for forgotten bb->aux values before commit_edge_insertions
1486 gcc_assert (bb->aux == &bb->aux);
1489 find_many_sub_basic_blocks (blocks);
1490 sbitmap_free (blocks);
1494 /* Print out RTL-specific basic block information (live information
1495 at start and end). */
1498 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1504 s_indent = (char *) alloca ((size_t) indent + 1);
1505 memset (s_indent, ' ', (size_t) indent);
1506 s_indent[indent] = '\0';
1510 df_dump_top (bb, outf);
1514 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1515 insn = NEXT_INSN (insn))
1516 print_rtl_single (outf, insn);
1520 df_dump_bottom (bb, outf);
1526 /* Like print_rtl, but also print out live information for the start of each
1530 print_rtl_with_bb (FILE *outf, const_rtx rtx_first)
1534 fprintf (outf, "(nil)\n");
1537 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1538 int max_uid = get_max_uid ();
1539 basic_block *start = XCNEWVEC (basic_block, max_uid);
1540 basic_block *end = XCNEWVEC (basic_block, max_uid);
1541 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1546 df_dump_start (outf);
1548 FOR_EACH_BB_REVERSE (bb)
1552 start[INSN_UID (BB_HEAD (bb))] = bb;
1553 end[INSN_UID (BB_END (bb))] = bb;
1554 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1556 enum bb_state state = IN_MULTIPLE_BB;
1558 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1560 in_bb_p[INSN_UID (x)] = state;
1562 if (x == BB_END (bb))
1567 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1570 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1575 fprintf (outf, ";; Start of basic block (");
1576 FOR_EACH_EDGE (e, ei, bb->preds)
1577 fprintf (outf, " %d", e->src->index);
1578 fprintf (outf, ") -> %d\n", bb->index);
1582 df_dump_top (bb, outf);
1585 FOR_EACH_EDGE (e, ei, bb->preds)
1587 fputs (";; Pred edge ", outf);
1588 dump_edge_info (outf, e, 0);
1593 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1594 && !NOTE_P (tmp_rtx)
1595 && !BARRIER_P (tmp_rtx))
1596 fprintf (outf, ";; Insn is not within a basic block\n");
1597 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1598 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1600 did_output = print_rtl_single (outf, tmp_rtx);
1602 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1607 fprintf (outf, ";; End of basic block %d -> (", bb->index);
1608 FOR_EACH_EDGE (e, ei, bb->succs)
1609 fprintf (outf, " %d", e->dest->index);
1610 fprintf (outf, ")\n");
1614 df_dump_bottom (bb, outf);
1618 FOR_EACH_EDGE (e, ei, bb->succs)
1620 fputs (";; Succ edge ", outf);
1621 dump_edge_info (outf, e, 1);
1634 if (current_function_epilogue_delay_list != 0)
1636 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1637 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1638 tmp_rtx = XEXP (tmp_rtx, 1))
1639 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1644 update_br_prob_note (basic_block bb)
1647 if (!JUMP_P (BB_END (bb)))
1649 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1650 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1652 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1655 /* Get the last insn associated with block BB (that includes barriers and
1656 tablejumps after BB). */
1658 get_last_bb_insn (basic_block bb)
1661 rtx end = BB_END (bb);
1663 /* Include any jump table following the basic block. */
1664 if (tablejump_p (end, NULL, &tmp))
1667 /* Include any barriers that may follow the basic block. */
1668 tmp = next_nonnote_insn (end);
1669 while (tmp && BARRIER_P (tmp))
1672 tmp = next_nonnote_insn (end);
1678 /* Verify the CFG and RTL consistency common for both underlying RTL and
1681 Currently it does following checks:
1683 - overlapping of basic blocks
1684 - insns with wrong BLOCK_FOR_INSN pointers
1685 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1686 - tails of basic blocks (ensure that boundary is necessary)
1687 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1688 and NOTE_INSN_BASIC_BLOCK
1689 - verify that no fall_thru edge crosses hot/cold partition boundaries
1690 - verify that there are no pending RTL branch predictions
1692 In future it can be extended check a lot of other stuff as well
1693 (reachability of basic blocks, life information, etc. etc.). */
1696 rtl_verify_flow_info_1 (void)
1702 /* Check the general integrity of the basic blocks. */
1703 FOR_EACH_BB_REVERSE (bb)
1707 if (!(bb->flags & BB_RTL))
1709 error ("BB_RTL flag not set for block %d", bb->index);
1713 FOR_BB_INSNS (bb, insn)
1714 if (BLOCK_FOR_INSN (insn) != bb)
1716 error ("insn %d basic block pointer is %d, should be %d",
1718 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1723 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1724 if (!BARRIER_P (insn)
1725 && BLOCK_FOR_INSN (insn) != NULL)
1727 error ("insn %d in header of bb %d has non-NULL basic block",
1728 INSN_UID (insn), bb->index);
1731 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1732 if (!BARRIER_P (insn)
1733 && BLOCK_FOR_INSN (insn) != NULL)
1735 error ("insn %d in footer of bb %d has non-NULL basic block",
1736 INSN_UID (insn), bb->index);
1741 /* Now check the basic blocks (boundaries etc.) */
1742 FOR_EACH_BB_REVERSE (bb)
1744 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1745 edge e, fallthru = NULL;
1749 if (JUMP_P (BB_END (bb))
1750 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1751 && EDGE_COUNT (bb->succs) >= 2
1752 && any_condjump_p (BB_END (bb)))
1754 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1755 && profile_status != PROFILE_ABSENT)
1757 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1758 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1762 FOR_EACH_EDGE (e, ei, bb->succs)
1764 if (e->flags & EDGE_FALLTHRU)
1766 n_fallthru++, fallthru = e;
1767 if ((e->flags & EDGE_CROSSING)
1768 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1769 && e->src != ENTRY_BLOCK_PTR
1770 && e->dest != EXIT_BLOCK_PTR))
1772 error ("fallthru edge crosses section boundary (bb %i)",
1778 if ((e->flags & ~(EDGE_DFS_BACK
1780 | EDGE_IRREDUCIBLE_LOOP
1782 | EDGE_CROSSING)) == 0)
1785 if (e->flags & EDGE_ABNORMAL_CALL)
1788 if (e->flags & EDGE_EH)
1790 else if (e->flags & EDGE_ABNORMAL)
1794 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
1795 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1797 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1801 && (!JUMP_P (BB_END (bb))
1802 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1803 || any_condjump_p (BB_END (bb))))))
1805 error ("too many outgoing branch edges from bb %i", bb->index);
1808 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1810 error ("fallthru edge after unconditional jump %i", bb->index);
1813 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1815 error ("wrong amount of branch edges after unconditional jump %i", bb->index);
1818 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1819 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1821 error ("wrong amount of branch edges after conditional jump %i",
1825 if (n_call && !CALL_P (BB_END (bb)))
1827 error ("call edges for non-call insn in bb %i", bb->index);
1831 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1832 && (!JUMP_P (BB_END (bb))
1833 || any_condjump_p (BB_END (bb))
1834 || any_uncondjump_p (BB_END (bb))))
1836 error ("abnormal edges for no purpose in bb %i", bb->index);
1840 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1841 /* We may have a barrier inside a basic block before dead code
1842 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1843 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1846 if (! BLOCK_FOR_INSN (x))
1848 ("insn %d inside basic block %d but block_for_insn is NULL",
1849 INSN_UID (x), bb->index);
1852 ("insn %d inside basic block %d but block_for_insn is %i",
1853 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1858 /* OK pointers are correct. Now check the header of basic
1859 block. It ought to contain optional CODE_LABEL followed
1860 by NOTE_BASIC_BLOCK. */
1864 if (BB_END (bb) == x)
1866 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1874 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1876 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1881 if (BB_END (bb) == x)
1882 /* Do checks for empty blocks here. */
1885 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1887 if (NOTE_INSN_BASIC_BLOCK_P (x))
1889 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1890 INSN_UID (x), bb->index);
1894 if (x == BB_END (bb))
1897 if (control_flow_insn_p (x))
1899 error ("in basic block %d:", bb->index);
1900 fatal_insn ("flow control insn inside a basic block", x);
1909 /* Verify the CFG and RTL consistency common for both underlying RTL and
1912 Currently it does following checks:
1913 - all checks of rtl_verify_flow_info_1
1914 - test head/end pointers
1915 - check that all insns are in the basic blocks
1916 (except the switch handling code, barriers and notes)
1917 - check that all returns are followed by barriers
1918 - check that all fallthru edge points to the adjacent blocks. */
1921 rtl_verify_flow_info (void)
1924 int err = rtl_verify_flow_info_1 ();
1926 rtx last_head = get_last_insn ();
1927 basic_block *bb_info;
1929 const rtx rtx_first = get_insns ();
1930 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
1931 const int max_uid = get_max_uid ();
1933 bb_info = XCNEWVEC (basic_block, max_uid);
1935 FOR_EACH_BB_REVERSE (bb)
1939 rtx head = BB_HEAD (bb);
1940 rtx end = BB_END (bb);
1942 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1944 /* Verify the end of the basic block is in the INSN chain. */
1948 /* And that the code outside of basic blocks has NULL bb field. */
1950 && BLOCK_FOR_INSN (x) != NULL)
1952 error ("insn %d outside of basic blocks has non-NULL bb field",
1960 error ("end insn %d for block %d not found in the insn stream",
1961 INSN_UID (end), bb->index);
1965 /* Work backwards from the end to the head of the basic block
1966 to verify the head is in the RTL chain. */
1967 for (; x != NULL_RTX; x = PREV_INSN (x))
1969 /* While walking over the insn chain, verify insns appear
1970 in only one basic block. */
1971 if (bb_info[INSN_UID (x)] != NULL)
1973 error ("insn %d is in multiple basic blocks (%d and %d)",
1974 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1978 bb_info[INSN_UID (x)] = bb;
1985 error ("head insn %d for block %d not found in the insn stream",
1986 INSN_UID (head), bb->index);
1990 last_head = PREV_INSN (x);
1992 FOR_EACH_EDGE (e, ei, bb->succs)
1993 if (e->flags & EDGE_FALLTHRU)
1999 /* Ensure existence of barrier in BB with no fallthru edges. */
2000 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2001 insn = NEXT_INSN (insn))
2003 || NOTE_INSN_BASIC_BLOCK_P (insn))
2005 error ("missing barrier after block %i", bb->index);
2010 else if (e->src != ENTRY_BLOCK_PTR
2011 && e->dest != EXIT_BLOCK_PTR)
2015 if (e->src->next_bb != e->dest)
2018 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2019 e->src->index, e->dest->index);
2023 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2024 insn = NEXT_INSN (insn))
2025 if (BARRIER_P (insn) || INSN_P (insn))
2027 error ("verify_flow_info: Incorrect fallthru %i->%i",
2028 e->src->index, e->dest->index);
2029 fatal_insn ("wrong insn in the fallthru edge", insn);
2035 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2037 /* Check that the code before the first basic block has NULL
2040 && BLOCK_FOR_INSN (x) != NULL)
2042 error ("insn %d outside of basic blocks has non-NULL bb field",
2050 last_bb_seen = ENTRY_BLOCK_PTR;
2052 for (x = rtx_first; x; x = NEXT_INSN (x))
2054 if (NOTE_INSN_BASIC_BLOCK_P (x))
2056 bb = NOTE_BASIC_BLOCK (x);
2059 if (bb != last_bb_seen->next_bb)
2060 internal_error ("basic blocks not laid down consecutively");
2062 curr_bb = last_bb_seen = bb;
2067 switch (GET_CODE (x))
2074 /* An addr_vec is placed outside any basic block. */
2076 && JUMP_P (NEXT_INSN (x))
2077 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2078 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2081 /* But in any case, non-deletable labels can appear anywhere. */
2085 fatal_insn ("insn outside basic block", x);
2090 && returnjump_p (x) && ! condjump_p (x)
2091 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2092 fatal_insn ("return not followed by barrier", x);
2093 if (curr_bb && x == BB_END (curr_bb))
2097 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2099 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2100 num_bb_notes, n_basic_blocks);
2105 /* Assume that the preceding pass has possibly eliminated jump instructions
2106 or converted the unconditional jumps. Eliminate the edges from CFG.
2107 Return true if any edges are eliminated. */
2110 purge_dead_edges (basic_block bb)
2113 rtx insn = BB_END (bb), note;
2114 bool purged = false;
2118 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2119 if (NONJUMP_INSN_P (insn)
2120 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2124 if (! may_trap_p (PATTERN (insn))
2125 || ((eqnote = find_reg_equal_equiv_note (insn))
2126 && ! may_trap_p (XEXP (eqnote, 0))))
2127 remove_note (insn, note);
2130 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2131 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2133 /* There are three types of edges we need to handle correctly here: EH
2134 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2135 latter can appear when nonlocal gotos are used. */
2136 if (e->flags & EDGE_EH)
2138 if (can_throw_internal (BB_END (bb))
2139 /* If this is a call edge, verify that this is a call insn. */
2140 && (! (e->flags & EDGE_ABNORMAL_CALL)
2141 || CALL_P (BB_END (bb))))
2147 else if (e->flags & EDGE_ABNORMAL_CALL)
2149 if (CALL_P (BB_END (bb))
2150 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2151 || INTVAL (XEXP (note, 0)) >= 0))
2164 df_set_bb_dirty (bb);
2174 /* We do care only about conditional jumps and simplejumps. */
2175 if (!any_condjump_p (insn)
2176 && !returnjump_p (insn)
2177 && !simplejump_p (insn))
2180 /* Branch probability/prediction notes are defined only for
2181 condjumps. We've possibly turned condjump into simplejump. */
2182 if (simplejump_p (insn))
2184 note = find_reg_note (insn, REG_BR_PROB, NULL);
2186 remove_note (insn, note);
2187 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2188 remove_note (insn, note);
2191 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2193 /* Avoid abnormal flags to leak from computed jumps turned
2194 into simplejumps. */
2196 e->flags &= ~EDGE_ABNORMAL;
2198 /* See if this edge is one we should keep. */
2199 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2200 /* A conditional jump can fall through into the next
2201 block, so we should keep the edge. */
2206 else if (e->dest != EXIT_BLOCK_PTR
2207 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2208 /* If the destination block is the target of the jump,
2214 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2215 /* If the destination block is the exit block, and this
2216 instruction is a return, then keep the edge. */
2221 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2222 /* Keep the edges that correspond to exceptions thrown by
2223 this instruction and rematerialize the EDGE_ABNORMAL
2224 flag we just cleared above. */
2226 e->flags |= EDGE_ABNORMAL;
2231 /* We do not need this edge. */
2232 df_set_bb_dirty (bb);
2237 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2241 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2246 /* Redistribute probabilities. */
2247 if (single_succ_p (bb))
2249 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2250 single_succ_edge (bb)->count = bb->count;
2254 note = find_reg_note (insn, REG_BR_PROB, NULL);
2258 b = BRANCH_EDGE (bb);
2259 f = FALLTHRU_EDGE (bb);
2260 b->probability = INTVAL (XEXP (note, 0));
2261 f->probability = REG_BR_PROB_BASE - b->probability;
2262 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2263 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2268 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2270 /* First, there should not be any EH or ABCALL edges resulting
2271 from non-local gotos and the like. If there were, we shouldn't
2272 have created the sibcall in the first place. Second, there
2273 should of course never have been a fallthru edge. */
2274 gcc_assert (single_succ_p (bb));
2275 gcc_assert (single_succ_edge (bb)->flags
2276 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2281 /* If we don't see a jump insn, we don't know exactly why the block would
2282 have been broken at this point. Look for a simple, non-fallthru edge,
2283 as these are only created by conditional branches. If we find such an
2284 edge we know that there used to be a jump here and can then safely
2285 remove all non-fallthru edges. */
2287 FOR_EACH_EDGE (e, ei, bb->succs)
2288 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2297 /* Remove all but the fake and fallthru edges. The fake edge may be
2298 the only successor for this block in the case of noreturn
2300 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2302 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2304 df_set_bb_dirty (bb);
2312 gcc_assert (single_succ_p (bb));
2314 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2315 single_succ_edge (bb)->count = bb->count;
2318 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2323 /* Search all basic blocks for potentially dead edges and purge them. Return
2324 true if some edge has been eliminated. */
2327 purge_all_dead_edges (void)
2334 bool purged_here = purge_dead_edges (bb);
2336 purged |= purged_here;
2342 /* Same as split_block but update cfg_layout structures. */
2345 cfg_layout_split_block (basic_block bb, void *insnp)
2347 rtx insn = (rtx) insnp;
2348 basic_block new_bb = rtl_split_block (bb, insn);
2350 new_bb->il.rtl->footer = bb->il.rtl->footer;
2351 bb->il.rtl->footer = NULL;
2356 /* Redirect Edge to DEST. */
2358 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2360 basic_block src = e->src;
2363 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2366 if (e->dest == dest)
2369 if (e->src != ENTRY_BLOCK_PTR
2370 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2372 df_set_bb_dirty (src);
2376 if (e->src == ENTRY_BLOCK_PTR
2377 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2380 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2381 e->src->index, dest->index);
2383 df_set_bb_dirty (e->src);
2384 redirect_edge_succ (e, dest);
2388 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2389 in the case the basic block appears to be in sequence. Avoid this
2392 if (e->flags & EDGE_FALLTHRU)
2394 /* Redirect any branch edges unified with the fallthru one. */
2395 if (JUMP_P (BB_END (src))
2396 && label_is_jump_target_p (BB_HEAD (e->dest),
2402 fprintf (dump_file, "Fallthru edge unified with branch "
2403 "%i->%i redirected to %i\n",
2404 e->src->index, e->dest->index, dest->index);
2405 e->flags &= ~EDGE_FALLTHRU;
2406 redirected = redirect_branch_edge (e, dest);
2407 gcc_assert (redirected);
2408 e->flags |= EDGE_FALLTHRU;
2409 df_set_bb_dirty (e->src);
2412 /* In case we are redirecting fallthru edge to the branch edge
2413 of conditional jump, remove it. */
2414 if (EDGE_COUNT (src->succs) == 2)
2416 /* Find the edge that is different from E. */
2417 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2420 && any_condjump_p (BB_END (src))
2421 && onlyjump_p (BB_END (src)))
2422 delete_insn (BB_END (src));
2424 ret = redirect_edge_succ_nodup (e, dest);
2426 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2427 e->src->index, e->dest->index, dest->index);
2430 ret = redirect_branch_edge (e, dest);
2432 /* We don't want simplejumps in the insn stream during cfglayout. */
2433 gcc_assert (!simplejump_p (BB_END (src)));
2435 df_set_bb_dirty (src);
2439 /* Simple wrapper as we always can redirect fallthru edges. */
2441 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2443 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2445 gcc_assert (redirected);
2449 /* Same as delete_basic_block but update cfg_layout structures. */
2452 cfg_layout_delete_block (basic_block bb)
2454 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2456 if (bb->il.rtl->header)
2458 next = BB_HEAD (bb);
2460 NEXT_INSN (prev) = bb->il.rtl->header;
2462 set_first_insn (bb->il.rtl->header);
2463 PREV_INSN (bb->il.rtl->header) = prev;
2464 insn = bb->il.rtl->header;
2465 while (NEXT_INSN (insn))
2466 insn = NEXT_INSN (insn);
2467 NEXT_INSN (insn) = next;
2468 PREV_INSN (next) = insn;
2470 next = NEXT_INSN (BB_END (bb));
2471 if (bb->il.rtl->footer)
2473 insn = bb->il.rtl->footer;
2476 if (BARRIER_P (insn))
2478 if (PREV_INSN (insn))
2479 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2481 bb->il.rtl->footer = NEXT_INSN (insn);
2482 if (NEXT_INSN (insn))
2483 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2487 insn = NEXT_INSN (insn);
2489 if (bb->il.rtl->footer)
2492 NEXT_INSN (insn) = bb->il.rtl->footer;
2493 PREV_INSN (bb->il.rtl->footer) = insn;
2494 while (NEXT_INSN (insn))
2495 insn = NEXT_INSN (insn);
2496 NEXT_INSN (insn) = next;
2498 PREV_INSN (next) = insn;
2500 set_last_insn (insn);
2503 if (bb->next_bb != EXIT_BLOCK_PTR)
2504 to = &bb->next_bb->il.rtl->header;
2506 to = &cfg_layout_function_footer;
2508 rtl_delete_block (bb);
2511 prev = NEXT_INSN (prev);
2513 prev = get_insns ();
2515 next = PREV_INSN (next);
2517 next = get_last_insn ();
2519 if (next && NEXT_INSN (next) != prev)
2521 remaints = unlink_insn_chain (prev, next);
2523 while (NEXT_INSN (insn))
2524 insn = NEXT_INSN (insn);
2525 NEXT_INSN (insn) = *to;
2527 PREV_INSN (*to) = insn;
2532 /* Return true when blocks A and B can be safely merged. */
2535 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2537 /* If we are partitioning hot/cold basic blocks, we don't want to
2538 mess up unconditional or indirect jumps that cross between hot
2541 Basic block partitioning may result in some jumps that appear to
2542 be optimizable (or blocks that appear to be mergeable), but which really
2543 must be left untouched (they are required to make it safely across
2544 partition boundaries). See the comments at the top of
2545 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2547 if (BB_PARTITION (a) != BB_PARTITION (b))
2550 /* There must be exactly one edge in between the blocks. */
2551 return (single_succ_p (a)
2552 && single_succ (a) == b
2553 && single_pred_p (b) == 1
2555 /* Must be simple edge. */
2556 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2557 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2558 /* If the jump insn has side effects, we can't kill the edge.
2559 When not optimizing, try_redirect_by_replacing_jump will
2560 not allow us to redirect an edge by replacing a table jump. */
2561 && (!JUMP_P (BB_END (a))
2562 || ((!optimize || reload_completed)
2563 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2566 /* Merge block A and B. The blocks must be mergeable. */
2569 cfg_layout_merge_blocks (basic_block a, basic_block b)
2571 #ifdef ENABLE_CHECKING
2572 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2576 fprintf (dump_file, "merging block %d into block %d\n", b->index, a->index);
2578 /* If there was a CODE_LABEL beginning B, delete it. */
2579 if (LABEL_P (BB_HEAD (b)))
2581 /* This might have been an EH label that no longer has incoming
2582 EH edges. Update data structures to match. */
2583 maybe_remove_eh_handler (BB_HEAD (b));
2585 delete_insn (BB_HEAD (b));
2588 /* We should have fallthru edge in a, or we can do dummy redirection to get
2590 if (JUMP_P (BB_END (a)))
2591 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2592 gcc_assert (!JUMP_P (BB_END (a)));
2594 /* Possible line number notes should appear in between. */
2595 if (b->il.rtl->header)
2597 rtx first = BB_END (a), last;
2599 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2600 delete_insn_chain (NEXT_INSN (first), last, false);
2601 b->il.rtl->header = NULL;
2604 /* In the case basic blocks are not adjacent, move them around. */
2605 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2607 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2609 emit_insn_after_noloc (first, BB_END (a), a);
2610 /* Skip possible DELETED_LABEL insn. */
2611 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2612 first = NEXT_INSN (first);
2613 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2615 delete_insn (first);
2617 /* Otherwise just re-associate the instructions. */
2622 for (insn = BB_HEAD (b);
2623 insn != NEXT_INSN (BB_END (b));
2624 insn = NEXT_INSN (insn))
2626 set_block_for_insn (insn, a);
2627 df_insn_change_bb (insn);
2631 /* Skip possible DELETED_LABEL insn. */
2632 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2633 insn = NEXT_INSN (insn);
2634 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2636 BB_END (a) = BB_END (b);
2640 df_bb_delete (b->index);
2642 /* Possible tablejumps and barriers should appear after the block. */
2643 if (b->il.rtl->footer)
2645 if (!a->il.rtl->footer)
2646 a->il.rtl->footer = b->il.rtl->footer;
2649 rtx last = a->il.rtl->footer;
2651 while (NEXT_INSN (last))
2652 last = NEXT_INSN (last);
2653 NEXT_INSN (last) = b->il.rtl->footer;
2654 PREV_INSN (b->il.rtl->footer) = last;
2656 b->il.rtl->footer = NULL;
2660 fprintf (dump_file, "Merged blocks %d and %d.\n",
2661 a->index, b->index);
2667 cfg_layout_split_edge (edge e)
2669 basic_block new_bb =
2670 create_basic_block (e->src != ENTRY_BLOCK_PTR
2671 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2674 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2675 redirect_edge_and_branch_force (e, new_bb);
2680 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2683 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2687 /* Return 1 if BB ends with a call, possibly followed by some
2688 instructions that must stay with the call, 0 otherwise. */
2691 rtl_block_ends_with_call_p (basic_block bb)
2693 rtx insn = BB_END (bb);
2695 while (!CALL_P (insn)
2696 && insn != BB_HEAD (bb)
2697 && keep_with_call_p (insn))
2698 insn = PREV_INSN (insn);
2699 return (CALL_P (insn));
2702 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2705 rtl_block_ends_with_condjump_p (const_basic_block bb)
2707 return any_condjump_p (BB_END (bb));
2710 /* Return true if we need to add fake edge to exit.
2711 Helper function for rtl_flow_call_edges_add. */
2714 need_fake_edge_p (const_rtx insn)
2720 && !SIBLING_CALL_P (insn)
2721 && !find_reg_note (insn, REG_NORETURN, NULL)
2722 && !CONST_OR_PURE_CALL_P (insn)))
2725 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2726 && MEM_VOLATILE_P (PATTERN (insn)))
2727 || (GET_CODE (PATTERN (insn)) == PARALLEL
2728 && asm_noperands (insn) != -1
2729 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2730 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2733 /* Add fake edges to the function exit for any non constant and non noreturn
2734 calls, volatile inline assembly in the bitmap of blocks specified by
2735 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2738 The goal is to expose cases in which entering a basic block does not imply
2739 that all subsequent instructions must be executed. */
2742 rtl_flow_call_edges_add (sbitmap blocks)
2745 int blocks_split = 0;
2746 int last_bb = last_basic_block;
2747 bool check_last_block = false;
2749 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2753 check_last_block = true;
2755 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2757 /* In the last basic block, before epilogue generation, there will be
2758 a fallthru edge to EXIT. Special care is required if the last insn
2759 of the last basic block is a call because make_edge folds duplicate
2760 edges, which would result in the fallthru edge also being marked
2761 fake, which would result in the fallthru edge being removed by
2762 remove_fake_edges, which would result in an invalid CFG.
2764 Moreover, we can't elide the outgoing fake edge, since the block
2765 profiler needs to take this into account in order to solve the minimal
2766 spanning tree in the case that the call doesn't return.
2768 Handle this by adding a dummy instruction in a new last basic block. */
2769 if (check_last_block)
2771 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2772 rtx insn = BB_END (bb);
2774 /* Back up past insns that must be kept in the same block as a call. */
2775 while (insn != BB_HEAD (bb)
2776 && keep_with_call_p (insn))
2777 insn = PREV_INSN (insn);
2779 if (need_fake_edge_p (insn))
2783 e = find_edge (bb, EXIT_BLOCK_PTR);
2786 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2787 commit_edge_insertions ();
2792 /* Now add fake edges to the function exit for any non constant
2793 calls since there is no way that we can determine if they will
2796 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
2798 basic_block bb = BASIC_BLOCK (i);
2805 if (blocks && !TEST_BIT (blocks, i))
2808 for (insn = BB_END (bb); ; insn = prev_insn)
2810 prev_insn = PREV_INSN (insn);
2811 if (need_fake_edge_p (insn))
2814 rtx split_at_insn = insn;
2816 /* Don't split the block between a call and an insn that should
2817 remain in the same block as the call. */
2819 while (split_at_insn != BB_END (bb)
2820 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2821 split_at_insn = NEXT_INSN (split_at_insn);
2823 /* The handling above of the final block before the epilogue
2824 should be enough to verify that there is no edge to the exit
2825 block in CFG already. Calling make_edge in such case would
2826 cause us to mark that edge as fake and remove it later. */
2828 #ifdef ENABLE_CHECKING
2829 if (split_at_insn == BB_END (bb))
2831 e = find_edge (bb, EXIT_BLOCK_PTR);
2832 gcc_assert (e == NULL);
2836 /* Note that the following may create a new basic block
2837 and renumber the existing basic blocks. */
2838 if (split_at_insn != BB_END (bb))
2840 e = split_block (bb, split_at_insn);
2845 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2848 if (insn == BB_HEAD (bb))
2854 verify_flow_info ();
2856 return blocks_split;
2859 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2860 the conditional branch target, SECOND_HEAD should be the fall-thru
2861 there is no need to handle this here the loop versioning code handles
2862 this. the reason for SECON_HEAD is that it is needed for condition
2863 in trees, and this should be of the same type since it is a hook. */
2865 rtl_lv_add_condition_to_bb (basic_block first_head ,
2866 basic_block second_head ATTRIBUTE_UNUSED,
2867 basic_block cond_bb, void *comp_rtx)
2869 rtx label, seq, jump;
2870 rtx op0 = XEXP ((rtx)comp_rtx, 0);
2871 rtx op1 = XEXP ((rtx)comp_rtx, 1);
2872 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
2873 enum machine_mode mode;
2876 label = block_label (first_head);
2877 mode = GET_MODE (op0);
2878 if (mode == VOIDmode)
2879 mode = GET_MODE (op1);
2882 op0 = force_operand (op0, NULL_RTX);
2883 op1 = force_operand (op1, NULL_RTX);
2884 do_compare_rtx_and_jump (op0, op1, comp, 0,
2885 mode, NULL_RTX, NULL_RTX, label);
2886 jump = get_last_insn ();
2887 JUMP_LABEL (jump) = label;
2888 LABEL_NUSES (label)++;
2892 /* Add the new cond , in the new head. */
2893 emit_insn_after(seq, BB_END(cond_bb));
2897 /* Given a block B with unconditional branch at its end, get the
2898 store the return the branch edge and the fall-thru edge in
2899 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
2901 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
2902 edge *fallthru_edge)
2904 edge e = EDGE_SUCC (b, 0);
2906 if (e->flags & EDGE_FALLTHRU)
2909 *branch_edge = EDGE_SUCC (b, 1);
2914 *fallthru_edge = EDGE_SUCC (b, 1);
2919 init_rtl_bb_info (basic_block bb)
2921 gcc_assert (!bb->il.rtl);
2922 bb->il.rtl = GGC_CNEW (struct rtl_bb_info);
2926 /* Add EXPR to the end of basic block BB. */
2929 insert_insn_end_bb_new (rtx pat, basic_block bb)
2931 rtx insn = BB_END (bb);
2935 while (NEXT_INSN (pat_end) != NULL_RTX)
2936 pat_end = NEXT_INSN (pat_end);
2938 /* If the last insn is a jump, insert EXPR in front [taking care to
2939 handle cc0, etc. properly]. Similarly we need to care trapping
2940 instructions in presence of non-call exceptions. */
2943 || (NONJUMP_INSN_P (insn)
2944 && (!single_succ_p (bb)
2945 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
2950 /* If this is a jump table, then we can't insert stuff here. Since
2951 we know the previous real insn must be the tablejump, we insert
2952 the new instruction just before the tablejump. */
2953 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
2954 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
2955 insn = prev_real_insn (insn);
2958 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
2959 if cc0 isn't set. */
2960 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
2962 insn = XEXP (note, 0);
2965 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
2966 if (maybe_cc0_setter
2967 && INSN_P (maybe_cc0_setter)
2968 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
2969 insn = maybe_cc0_setter;
2972 /* FIXME: What if something in cc0/jump uses value set in new
2974 new_insn = emit_insn_before_noloc (pat, insn, bb);
2977 /* Likewise if the last insn is a call, as will happen in the presence
2978 of exception handling. */
2979 else if (CALL_P (insn)
2980 && (!single_succ_p (bb)
2981 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
2983 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
2984 we search backward and place the instructions before the first
2985 parameter is loaded. Do this for everyone for consistency and a
2986 presumption that we'll get better code elsewhere as well. */
2988 /* Since different machines initialize their parameter registers
2989 in different orders, assume nothing. Collect the set of all
2990 parameter registers. */
2991 insn = find_first_parameter_load (insn, BB_HEAD (bb));
2993 /* If we found all the parameter loads, then we want to insert
2994 before the first parameter load.
2996 If we did not find all the parameter loads, then we might have
2997 stopped on the head of the block, which could be a CODE_LABEL.
2998 If we inserted before the CODE_LABEL, then we would be putting
2999 the insn in the wrong basic block. In that case, put the insn
3000 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
3001 while (LABEL_P (insn)
3002 || NOTE_INSN_BASIC_BLOCK_P (insn))
3003 insn = NEXT_INSN (insn);
3005 new_insn = emit_insn_before_noloc (pat, insn, bb);
3008 new_insn = emit_insn_after_noloc (pat, insn, bb);
3013 /* Returns true if it is possible to remove edge E by redirecting
3014 it to the destination of the other edge from E->src. */
3017 rtl_can_remove_branch_p (const_edge e)
3019 const_basic_block src = e->src;
3020 const_basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3021 const_rtx insn = BB_END (src), set;
3023 /* The conditions are taken from try_redirect_by_replacing_jump. */
3024 if (target == EXIT_BLOCK_PTR)
3027 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3030 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3031 || BB_PARTITION (src) != BB_PARTITION (target))
3034 if (!onlyjump_p (insn)
3035 || tablejump_p (insn, NULL, NULL))
3038 set = single_set (insn);
3039 if (!set || side_effects_p (set))
3045 /* Implementation of CFG manipulation for linearized RTL. */
3046 struct cfg_hooks rtl_cfg_hooks = {
3048 rtl_verify_flow_info,
3050 rtl_create_basic_block,
3051 rtl_redirect_edge_and_branch,
3052 rtl_redirect_edge_and_branch_force,
3053 rtl_can_remove_branch_p,
3056 rtl_move_block_after,
3057 rtl_can_merge_blocks, /* can_merge_blocks_p */
3061 NULL, /* can_duplicate_block_p */
3062 NULL, /* duplicate_block */
3064 rtl_make_forwarder_block,
3065 rtl_tidy_fallthru_edge,
3066 rtl_block_ends_with_call_p,
3067 rtl_block_ends_with_condjump_p,
3068 rtl_flow_call_edges_add,
3069 NULL, /* execute_on_growing_pred */
3070 NULL, /* execute_on_shrinking_pred */
3071 NULL, /* duplicate loop for trees */
3072 NULL, /* lv_add_condition_to_bb */
3073 NULL, /* lv_adjust_loop_header_phi*/
3074 NULL, /* extract_cond_bb_edges */
3075 NULL /* flush_pending_stmts */
3078 /* Implementation of CFG manipulation for cfg layout RTL, where
3079 basic block connected via fallthru edges does not have to be adjacent.
3080 This representation will hopefully become the default one in future
3081 version of the compiler. */
3083 /* We do not want to declare these functions in a header file, since they
3084 should only be used through the cfghooks interface, and we do not want to
3085 move them here since it would require also moving quite a lot of related
3086 code. They are in cfglayout.c. */
3087 extern bool cfg_layout_can_duplicate_bb_p (const_basic_block);
3088 extern basic_block cfg_layout_duplicate_bb (basic_block);
3090 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3092 rtl_verify_flow_info_1,
3094 cfg_layout_create_basic_block,
3095 cfg_layout_redirect_edge_and_branch,
3096 cfg_layout_redirect_edge_and_branch_force,
3097 rtl_can_remove_branch_p,
3098 cfg_layout_delete_block,
3099 cfg_layout_split_block,
3100 rtl_move_block_after,
3101 cfg_layout_can_merge_blocks_p,
3102 cfg_layout_merge_blocks,
3105 cfg_layout_can_duplicate_bb_p,
3106 cfg_layout_duplicate_bb,
3107 cfg_layout_split_edge,
3108 rtl_make_forwarder_block,
3110 rtl_block_ends_with_call_p,
3111 rtl_block_ends_with_condjump_p,
3112 rtl_flow_call_edges_add,
3113 NULL, /* execute_on_growing_pred */
3114 NULL, /* execute_on_shrinking_pred */
3115 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3116 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3117 NULL, /* lv_adjust_loop_header_phi*/
3118 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3119 NULL /* flush_pending_stmts */