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 (rtx);
66 static int can_delete_label_p (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 (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 (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. */
628 rtl_can_merge_blocks (basic_block a,basic_block b)
630 /* If we are partitioning hot/cold basic blocks, we don't want to
631 mess up unconditional or indirect jumps that cross between hot
634 Basic block partitioning may result in some jumps that appear to
635 be optimizable (or blocks that appear to be mergeable), but which really
636 must be left untouched (they are required to make it safely across
637 partition boundaries). See the comments at the top of
638 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
640 if (BB_PARTITION (a) != BB_PARTITION (b))
643 /* There must be exactly one edge in between the blocks. */
644 return (single_succ_p (a)
645 && single_succ (a) == b
648 /* Must be simple edge. */
649 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
651 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
652 /* If the jump insn has side effects,
653 we can't kill the edge. */
654 && (!JUMP_P (BB_END (a))
656 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
659 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
663 block_label (basic_block block)
665 if (block == EXIT_BLOCK_PTR)
668 if (!LABEL_P (BB_HEAD (block)))
670 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
673 return BB_HEAD (block);
676 /* Attempt to perform edge redirection by replacing possibly complex jump
677 instruction by unconditional jump or removing jump completely. This can
678 apply only if all edges now point to the same block. The parameters and
679 return values are equivalent to redirect_edge_and_branch. */
682 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
684 basic_block src = e->src;
685 rtx insn = BB_END (src), kill_from;
689 /* If we are partitioning hot/cold basic blocks, we don't want to
690 mess up unconditional or indirect jumps that cross between hot
693 Basic block partitioning may result in some jumps that appear to
694 be optimizable (or blocks that appear to be mergeable), but which really
695 must be left untouched (they are required to make it safely across
696 partition boundaries). See the comments at the top of
697 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
699 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
700 || BB_PARTITION (src) != BB_PARTITION (target))
703 /* We can replace or remove a complex jump only when we have exactly
704 two edges. Also, if we have exactly one outgoing edge, we can
706 if (EDGE_COUNT (src->succs) >= 3
707 /* Verify that all targets will be TARGET. Specifically, the
708 edge that is not E must also go to TARGET. */
709 || (EDGE_COUNT (src->succs) == 2
710 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
713 if (!onlyjump_p (insn))
715 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
718 /* Avoid removing branch with side effects. */
719 set = single_set (insn);
720 if (!set || side_effects_p (set))
723 /* In case we zap a conditional jump, we'll need to kill
724 the cc0 setter too. */
727 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
728 && only_sets_cc0_p (PREV_INSN (insn)))
729 kill_from = PREV_INSN (insn);
732 /* See if we can create the fallthru edge. */
733 if (in_cfglayout || can_fallthru (src, target))
736 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
739 /* Selectively unlink whole insn chain. */
742 rtx insn = src->il.rtl->footer;
744 delete_insn_chain (kill_from, BB_END (src), false);
746 /* Remove barriers but keep jumptables. */
749 if (BARRIER_P (insn))
751 if (PREV_INSN (insn))
752 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
754 src->il.rtl->footer = NEXT_INSN (insn);
755 if (NEXT_INSN (insn))
756 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
760 insn = NEXT_INSN (insn);
764 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)),
768 /* If this already is simplejump, redirect it. */
769 else if (simplejump_p (insn))
771 if (e->dest == target)
774 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
775 INSN_UID (insn), e->dest->index, target->index);
776 if (!redirect_jump (insn, block_label (target), 0))
778 gcc_assert (target == EXIT_BLOCK_PTR);
783 /* Cannot do anything for target exit block. */
784 else if (target == EXIT_BLOCK_PTR)
787 /* Or replace possibly complicated jump insn by simple jump insn. */
790 rtx target_label = block_label (target);
791 rtx barrier, label, table;
793 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
794 JUMP_LABEL (BB_END (src)) = target_label;
795 LABEL_NUSES (target_label)++;
797 fprintf (dump_file, "Replacing insn %i by jump %i\n",
798 INSN_UID (insn), INSN_UID (BB_END (src)));
801 delete_insn_chain (kill_from, insn, false);
803 /* Recognize a tablejump that we are converting to a
804 simple jump and remove its associated CODE_LABEL
805 and ADDR_VEC or ADDR_DIFF_VEC. */
806 if (tablejump_p (insn, &label, &table))
807 delete_insn_chain (label, table, false);
809 barrier = next_nonnote_insn (BB_END (src));
810 if (!barrier || !BARRIER_P (barrier))
811 emit_barrier_after (BB_END (src));
814 if (barrier != NEXT_INSN (BB_END (src)))
816 /* Move the jump before barrier so that the notes
817 which originally were or were created before jump table are
818 inside the basic block. */
819 rtx new_insn = BB_END (src);
822 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
823 tmp = NEXT_INSN (tmp))
825 set_block_for_insn (tmp, src);
826 df_insn_change_bb (tmp);
829 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
830 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
832 NEXT_INSN (new_insn) = barrier;
833 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
835 PREV_INSN (new_insn) = PREV_INSN (barrier);
836 PREV_INSN (barrier) = new_insn;
841 /* Keep only one edge out and set proper flags. */
842 if (!single_succ_p (src))
844 gcc_assert (single_succ_p (src));
846 e = single_succ_edge (src);
848 e->flags = EDGE_FALLTHRU;
852 e->probability = REG_BR_PROB_BASE;
853 e->count = src->count;
855 if (e->dest != target)
856 redirect_edge_succ (e, target);
860 /* Redirect edge representing branch of (un)conditional jump or tablejump,
863 redirect_branch_edge (edge e, basic_block target)
866 rtx old_label = BB_HEAD (e->dest);
867 basic_block src = e->src;
868 rtx insn = BB_END (src);
870 /* We can only redirect non-fallthru edges of jump insn. */
871 if (e->flags & EDGE_FALLTHRU)
873 else if (!JUMP_P (insn))
876 /* Recognize a tablejump and adjust all matching cases. */
877 if (tablejump_p (insn, NULL, &tmp))
881 rtx new_label = block_label (target);
883 if (target == EXIT_BLOCK_PTR)
885 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
886 vec = XVEC (PATTERN (tmp), 0);
888 vec = XVEC (PATTERN (tmp), 1);
890 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
891 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
893 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
894 --LABEL_NUSES (old_label);
895 ++LABEL_NUSES (new_label);
898 /* Handle casesi dispatch insns. */
899 if ((tmp = single_set (insn)) != NULL
900 && SET_DEST (tmp) == pc_rtx
901 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
902 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
903 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
905 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (Pmode,
907 --LABEL_NUSES (old_label);
908 ++LABEL_NUSES (new_label);
913 /* ?? We may play the games with moving the named labels from
914 one basic block to the other in case only one computed_jump is
916 if (computed_jump_p (insn)
917 /* A return instruction can't be redirected. */
918 || returnjump_p (insn))
921 /* If the insn doesn't go where we think, we're confused. */
922 gcc_assert (JUMP_LABEL (insn) == old_label);
924 /* If the substitution doesn't succeed, die. This can happen
925 if the back end emitted unrecognizable instructions or if
926 target is exit block on some arches. */
927 if (!redirect_jump (insn, block_label (target), 0))
929 gcc_assert (target == EXIT_BLOCK_PTR);
935 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
936 e->src->index, e->dest->index, target->index);
938 if (e->dest != target)
939 e = redirect_edge_succ_nodup (e, target);
944 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
945 expense of adding new instructions or reordering basic blocks.
947 Function can be also called with edge destination equivalent to the TARGET.
948 Then it should try the simplifications and do nothing if none is possible.
950 Return edge representing the branch if transformation succeeded. Return NULL
952 We still return NULL in case E already destinated TARGET and we didn't
953 managed to simplify instruction stream. */
956 rtl_redirect_edge_and_branch (edge e, basic_block target)
959 basic_block src = e->src;
961 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
964 if (e->dest == target)
967 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
969 df_set_bb_dirty (src);
973 ret = redirect_branch_edge (e, target);
977 df_set_bb_dirty (src);
981 /* Like force_nonfallthru below, but additionally performs redirection
982 Used by redirect_edge_and_branch_force. */
985 force_nonfallthru_and_redirect (edge e, basic_block target)
987 basic_block jump_block, new_bb = NULL, src = e->src;
990 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 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP,
1100 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1101 new_edge->probability = e->probability;
1102 new_edge->count = e->count;
1104 /* Redirect old edge. */
1105 redirect_edge_pred (e, jump_block);
1106 e->probability = REG_BR_PROB_BASE;
1108 new_bb = jump_block;
1111 jump_block = e->src;
1113 e->flags &= ~EDGE_FALLTHRU;
1114 if (target == EXIT_BLOCK_PTR)
1117 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1124 rtx label = block_label (target);
1125 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
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 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1401 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1406 /* Now that we've found the spot, do the insertion. */
1410 emit_insn_before_noloc (insns, before, bb);
1411 last = prev_nonnote_insn (before);
1414 last = emit_insn_after_noloc (insns, after, bb);
1416 if (returnjump_p (last))
1418 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1419 This is not currently a problem because this only happens
1420 for the (single) epilogue, which already has a fallthru edge
1423 e = single_succ_edge (bb);
1424 gcc_assert (e->dest == EXIT_BLOCK_PTR
1425 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1427 e->flags &= ~EDGE_FALLTHRU;
1428 emit_barrier_after (last);
1431 delete_insn (before);
1434 gcc_assert (!JUMP_P (last));
1436 /* Mark the basic block for find_many_sub_basic_blocks. */
1437 if (current_ir_type () != IR_RTL_CFGLAYOUT)
1441 /* Update the CFG for all queued instructions. */
1444 commit_edge_insertions (void)
1448 bool changed = false;
1450 #ifdef ENABLE_CHECKING
1451 verify_flow_info ();
1454 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1459 FOR_EACH_EDGE (e, ei, bb->succs)
1463 commit_one_edge_insertion (e);
1470 /* In the old rtl CFG API, it was OK to insert control flow on an
1471 edge, apparently? In cfglayout mode, this will *not* work, and
1472 the caller is responsible for making sure that control flow is
1473 valid at all times. */
1474 if (current_ir_type () == IR_RTL_CFGLAYOUT)
1477 blocks = sbitmap_alloc (last_basic_block);
1478 sbitmap_zero (blocks);
1482 SET_BIT (blocks, bb->index);
1483 /* Check for forgotten bb->aux values before commit_edge_insertions
1485 gcc_assert (bb->aux == &bb->aux);
1488 find_many_sub_basic_blocks (blocks);
1489 sbitmap_free (blocks);
1493 /* Print out RTL-specific basic block information (live information
1494 at start and end). */
1497 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1503 s_indent = (char *) alloca ((size_t) indent + 1);
1504 memset (s_indent, ' ', (size_t) indent);
1505 s_indent[indent] = '\0';
1509 df_dump_top (bb, outf);
1513 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1514 insn = NEXT_INSN (insn))
1515 print_rtl_single (outf, insn);
1519 df_dump_bottom (bb, outf);
1525 /* Like print_rtl, but also print out live information for the start of each
1529 print_rtl_with_bb (FILE *outf, const_rtx rtx_first)
1533 fprintf (outf, "(nil)\n");
1536 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1537 int max_uid = get_max_uid ();
1538 basic_block *start = XCNEWVEC (basic_block, max_uid);
1539 basic_block *end = XCNEWVEC (basic_block, max_uid);
1540 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1545 df_dump_start (outf);
1547 FOR_EACH_BB_REVERSE (bb)
1551 start[INSN_UID (BB_HEAD (bb))] = bb;
1552 end[INSN_UID (BB_END (bb))] = bb;
1553 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1555 enum bb_state state = IN_MULTIPLE_BB;
1557 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1559 in_bb_p[INSN_UID (x)] = state;
1561 if (x == BB_END (bb))
1566 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1569 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1574 fprintf (outf, ";; Start of basic block (");
1575 FOR_EACH_EDGE (e, ei, bb->preds)
1576 fprintf (outf, " %d", e->src->index);
1577 fprintf (outf, ") -> %d\n", bb->index);
1581 df_dump_top (bb, outf);
1584 FOR_EACH_EDGE (e, ei, bb->preds)
1586 fputs (";; Pred edge ", outf);
1587 dump_edge_info (outf, e, 0);
1592 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1593 && !NOTE_P (tmp_rtx)
1594 && !BARRIER_P (tmp_rtx))
1595 fprintf (outf, ";; Insn is not within a basic block\n");
1596 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1597 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1599 did_output = print_rtl_single (outf, tmp_rtx);
1601 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1606 fprintf (outf, ";; End of basic block %d -> (", bb->index);
1607 FOR_EACH_EDGE (e, ei, bb->succs)
1608 fprintf (outf, " %d", e->dest->index);
1609 fprintf (outf, ")\n");
1613 df_dump_bottom (bb, outf);
1617 FOR_EACH_EDGE (e, ei, bb->succs)
1619 fputs (";; Succ edge ", outf);
1620 dump_edge_info (outf, e, 1);
1633 if (current_function_epilogue_delay_list != 0)
1635 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1636 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1637 tmp_rtx = XEXP (tmp_rtx, 1))
1638 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1643 update_br_prob_note (basic_block bb)
1646 if (!JUMP_P (BB_END (bb)))
1648 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1649 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1651 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1654 /* Get the last insn associated with block BB (that includes barriers and
1655 tablejumps after BB). */
1657 get_last_bb_insn (basic_block bb)
1660 rtx end = BB_END (bb);
1662 /* Include any jump table following the basic block. */
1663 if (tablejump_p (end, NULL, &tmp))
1666 /* Include any barriers that may follow the basic block. */
1667 tmp = next_nonnote_insn (end);
1668 while (tmp && BARRIER_P (tmp))
1671 tmp = next_nonnote_insn (end);
1677 /* Verify the CFG and RTL consistency common for both underlying RTL and
1680 Currently it does following checks:
1682 - overlapping of basic blocks
1683 - insns with wrong BLOCK_FOR_INSN pointers
1684 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1685 - tails of basic blocks (ensure that boundary is necessary)
1686 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1687 and NOTE_INSN_BASIC_BLOCK
1688 - verify that no fall_thru edge crosses hot/cold partition boundaries
1689 - verify that there are no pending RTL branch predictions
1691 In future it can be extended check a lot of other stuff as well
1692 (reachability of basic blocks, life information, etc. etc.). */
1695 rtl_verify_flow_info_1 (void)
1701 /* Check the general integrity of the basic blocks. */
1702 FOR_EACH_BB_REVERSE (bb)
1706 if (!(bb->flags & BB_RTL))
1708 error ("BB_RTL flag not set for block %d", bb->index);
1712 FOR_BB_INSNS (bb, insn)
1713 if (BLOCK_FOR_INSN (insn) != bb)
1715 error ("insn %d basic block pointer is %d, should be %d",
1717 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1722 for (insn = bb->il.rtl->header; insn; insn = NEXT_INSN (insn))
1723 if (!BARRIER_P (insn)
1724 && BLOCK_FOR_INSN (insn) != NULL)
1726 error ("insn %d in header of bb %d has non-NULL basic block",
1727 INSN_UID (insn), bb->index);
1730 for (insn = bb->il.rtl->footer; insn; insn = NEXT_INSN (insn))
1731 if (!BARRIER_P (insn)
1732 && BLOCK_FOR_INSN (insn) != NULL)
1734 error ("insn %d in footer of bb %d has non-NULL basic block",
1735 INSN_UID (insn), bb->index);
1740 /* Now check the basic blocks (boundaries etc.) */
1741 FOR_EACH_BB_REVERSE (bb)
1743 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1744 edge e, fallthru = NULL;
1748 if (JUMP_P (BB_END (bb))
1749 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1750 && EDGE_COUNT (bb->succs) >= 2
1751 && any_condjump_p (BB_END (bb)))
1753 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1754 && profile_status != PROFILE_ABSENT)
1756 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1757 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1761 FOR_EACH_EDGE (e, ei, bb->succs)
1763 if (e->flags & EDGE_FALLTHRU)
1765 n_fallthru++, fallthru = e;
1766 if ((e->flags & EDGE_CROSSING)
1767 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1768 && e->src != ENTRY_BLOCK_PTR
1769 && e->dest != EXIT_BLOCK_PTR))
1771 error ("fallthru edge crosses section boundary (bb %i)",
1777 if ((e->flags & ~(EDGE_DFS_BACK
1779 | EDGE_IRREDUCIBLE_LOOP
1781 | EDGE_CROSSING)) == 0)
1784 if (e->flags & EDGE_ABNORMAL_CALL)
1787 if (e->flags & EDGE_EH)
1789 else if (e->flags & EDGE_ABNORMAL)
1793 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
1794 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1796 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1800 && (!JUMP_P (BB_END (bb))
1801 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1802 || any_condjump_p (BB_END (bb))))))
1804 error ("too many outgoing branch edges from bb %i", bb->index);
1807 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1809 error ("fallthru edge after unconditional jump %i", bb->index);
1812 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1814 error ("wrong amount of branch edges after unconditional jump %i", bb->index);
1817 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1818 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1820 error ("wrong amount of branch edges after conditional jump %i",
1824 if (n_call && !CALL_P (BB_END (bb)))
1826 error ("call edges for non-call insn in bb %i", bb->index);
1830 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1831 && (!JUMP_P (BB_END (bb))
1832 || any_condjump_p (BB_END (bb))
1833 || any_uncondjump_p (BB_END (bb))))
1835 error ("abnormal edges for no purpose in bb %i", bb->index);
1839 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1840 /* We may have a barrier inside a basic block before dead code
1841 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1842 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1845 if (! BLOCK_FOR_INSN (x))
1847 ("insn %d inside basic block %d but block_for_insn is NULL",
1848 INSN_UID (x), bb->index);
1851 ("insn %d inside basic block %d but block_for_insn is %i",
1852 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1857 /* OK pointers are correct. Now check the header of basic
1858 block. It ought to contain optional CODE_LABEL followed
1859 by NOTE_BASIC_BLOCK. */
1863 if (BB_END (bb) == x)
1865 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1873 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1875 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1880 if (BB_END (bb) == x)
1881 /* Do checks for empty blocks here. */
1884 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1886 if (NOTE_INSN_BASIC_BLOCK_P (x))
1888 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1889 INSN_UID (x), bb->index);
1893 if (x == BB_END (bb))
1896 if (control_flow_insn_p (x))
1898 error ("in basic block %d:", bb->index);
1899 fatal_insn ("flow control insn inside a basic block", x);
1908 /* Verify the CFG and RTL consistency common for both underlying RTL and
1911 Currently it does following checks:
1912 - all checks of rtl_verify_flow_info_1
1913 - test head/end pointers
1914 - check that all insns are in the basic blocks
1915 (except the switch handling code, barriers and notes)
1916 - check that all returns are followed by barriers
1917 - check that all fallthru edge points to the adjacent blocks. */
1920 rtl_verify_flow_info (void)
1923 int err = rtl_verify_flow_info_1 ();
1925 rtx last_head = get_last_insn ();
1926 basic_block *bb_info;
1928 const rtx rtx_first = get_insns ();
1929 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
1930 const int max_uid = get_max_uid ();
1932 bb_info = XCNEWVEC (basic_block, max_uid);
1934 FOR_EACH_BB_REVERSE (bb)
1938 rtx head = BB_HEAD (bb);
1939 rtx end = BB_END (bb);
1941 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1943 /* Verify the end of the basic block is in the INSN chain. */
1947 /* And that the code outside of basic blocks has NULL bb field. */
1949 && BLOCK_FOR_INSN (x) != NULL)
1951 error ("insn %d outside of basic blocks has non-NULL bb field",
1959 error ("end insn %d for block %d not found in the insn stream",
1960 INSN_UID (end), bb->index);
1964 /* Work backwards from the end to the head of the basic block
1965 to verify the head is in the RTL chain. */
1966 for (; x != NULL_RTX; x = PREV_INSN (x))
1968 /* While walking over the insn chain, verify insns appear
1969 in only one basic block. */
1970 if (bb_info[INSN_UID (x)] != NULL)
1972 error ("insn %d is in multiple basic blocks (%d and %d)",
1973 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1977 bb_info[INSN_UID (x)] = bb;
1984 error ("head insn %d for block %d not found in the insn stream",
1985 INSN_UID (head), bb->index);
1989 last_head = PREV_INSN (x);
1991 FOR_EACH_EDGE (e, ei, bb->succs)
1992 if (e->flags & EDGE_FALLTHRU)
1998 /* Ensure existence of barrier in BB with no fallthru edges. */
1999 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2000 insn = NEXT_INSN (insn))
2002 || NOTE_INSN_BASIC_BLOCK_P (insn))
2004 error ("missing barrier after block %i", bb->index);
2009 else if (e->src != ENTRY_BLOCK_PTR
2010 && e->dest != EXIT_BLOCK_PTR)
2014 if (e->src->next_bb != e->dest)
2017 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2018 e->src->index, e->dest->index);
2022 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2023 insn = NEXT_INSN (insn))
2024 if (BARRIER_P (insn) || INSN_P (insn))
2026 error ("verify_flow_info: Incorrect fallthru %i->%i",
2027 e->src->index, e->dest->index);
2028 fatal_insn ("wrong insn in the fallthru edge", insn);
2034 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
2036 /* Check that the code before the first basic block has NULL
2039 && BLOCK_FOR_INSN (x) != NULL)
2041 error ("insn %d outside of basic blocks has non-NULL bb field",
2049 last_bb_seen = ENTRY_BLOCK_PTR;
2051 for (x = rtx_first; x; x = NEXT_INSN (x))
2053 if (NOTE_INSN_BASIC_BLOCK_P (x))
2055 bb = NOTE_BASIC_BLOCK (x);
2058 if (bb != last_bb_seen->next_bb)
2059 internal_error ("basic blocks not laid down consecutively");
2061 curr_bb = last_bb_seen = bb;
2066 switch (GET_CODE (x))
2073 /* An addr_vec is placed outside any basic block. */
2075 && JUMP_P (NEXT_INSN (x))
2076 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2077 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2080 /* But in any case, non-deletable labels can appear anywhere. */
2084 fatal_insn ("insn outside basic block", x);
2089 && returnjump_p (x) && ! condjump_p (x)
2090 && ! (next_nonnote_insn (x) && BARRIER_P (next_nonnote_insn (x))))
2091 fatal_insn ("return not followed by barrier", x);
2092 if (curr_bb && x == BB_END (curr_bb))
2096 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2098 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2099 num_bb_notes, n_basic_blocks);
2104 /* Assume that the preceding pass has possibly eliminated jump instructions
2105 or converted the unconditional jumps. Eliminate the edges from CFG.
2106 Return true if any edges are eliminated. */
2109 purge_dead_edges (basic_block bb)
2112 rtx insn = BB_END (bb), note;
2113 bool purged = false;
2117 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2118 if (NONJUMP_INSN_P (insn)
2119 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2123 if (! may_trap_p (PATTERN (insn))
2124 || ((eqnote = find_reg_equal_equiv_note (insn))
2125 && ! may_trap_p (XEXP (eqnote, 0))))
2126 remove_note (insn, note);
2129 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2130 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2132 /* There are three types of edges we need to handle correctly here: EH
2133 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2134 latter can appear when nonlocal gotos are used. */
2135 if (e->flags & EDGE_EH)
2137 if (can_throw_internal (BB_END (bb))
2138 /* If this is a call edge, verify that this is a call insn. */
2139 && (! (e->flags & EDGE_ABNORMAL_CALL)
2140 || CALL_P (BB_END (bb))))
2146 else if (e->flags & EDGE_ABNORMAL_CALL)
2148 if (CALL_P (BB_END (bb))
2149 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2150 || INTVAL (XEXP (note, 0)) >= 0))
2163 df_set_bb_dirty (bb);
2173 /* We do care only about conditional jumps and simplejumps. */
2174 if (!any_condjump_p (insn)
2175 && !returnjump_p (insn)
2176 && !simplejump_p (insn))
2179 /* Branch probability/prediction notes are defined only for
2180 condjumps. We've possibly turned condjump into simplejump. */
2181 if (simplejump_p (insn))
2183 note = find_reg_note (insn, REG_BR_PROB, NULL);
2185 remove_note (insn, note);
2186 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2187 remove_note (insn, note);
2190 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2192 /* Avoid abnormal flags to leak from computed jumps turned
2193 into simplejumps. */
2195 e->flags &= ~EDGE_ABNORMAL;
2197 /* See if this edge is one we should keep. */
2198 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2199 /* A conditional jump can fall through into the next
2200 block, so we should keep the edge. */
2205 else if (e->dest != EXIT_BLOCK_PTR
2206 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2207 /* If the destination block is the target of the jump,
2213 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2214 /* If the destination block is the exit block, and this
2215 instruction is a return, then keep the edge. */
2220 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2221 /* Keep the edges that correspond to exceptions thrown by
2222 this instruction and rematerialize the EDGE_ABNORMAL
2223 flag we just cleared above. */
2225 e->flags |= EDGE_ABNORMAL;
2230 /* We do not need this edge. */
2231 df_set_bb_dirty (bb);
2236 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2240 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2245 /* Redistribute probabilities. */
2246 if (single_succ_p (bb))
2248 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2249 single_succ_edge (bb)->count = bb->count;
2253 note = find_reg_note (insn, REG_BR_PROB, NULL);
2257 b = BRANCH_EDGE (bb);
2258 f = FALLTHRU_EDGE (bb);
2259 b->probability = INTVAL (XEXP (note, 0));
2260 f->probability = REG_BR_PROB_BASE - b->probability;
2261 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2262 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2267 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2269 /* First, there should not be any EH or ABCALL edges resulting
2270 from non-local gotos and the like. If there were, we shouldn't
2271 have created the sibcall in the first place. Second, there
2272 should of course never have been a fallthru edge. */
2273 gcc_assert (single_succ_p (bb));
2274 gcc_assert (single_succ_edge (bb)->flags
2275 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2280 /* If we don't see a jump insn, we don't know exactly why the block would
2281 have been broken at this point. Look for a simple, non-fallthru edge,
2282 as these are only created by conditional branches. If we find such an
2283 edge we know that there used to be a jump here and can then safely
2284 remove all non-fallthru edges. */
2286 FOR_EACH_EDGE (e, ei, bb->succs)
2287 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2296 /* Remove all but the fake and fallthru edges. The fake edge may be
2297 the only successor for this block in the case of noreturn
2299 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2301 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2303 df_set_bb_dirty (bb);
2311 gcc_assert (single_succ_p (bb));
2313 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2314 single_succ_edge (bb)->count = bb->count;
2317 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2322 /* Search all basic blocks for potentially dead edges and purge them. Return
2323 true if some edge has been eliminated. */
2326 purge_all_dead_edges (void)
2333 bool purged_here = purge_dead_edges (bb);
2335 purged |= purged_here;
2341 /* Same as split_block but update cfg_layout structures. */
2344 cfg_layout_split_block (basic_block bb, void *insnp)
2346 rtx insn = (rtx) insnp;
2347 basic_block new_bb = rtl_split_block (bb, insn);
2349 new_bb->il.rtl->footer = bb->il.rtl->footer;
2350 bb->il.rtl->footer = NULL;
2355 /* Redirect Edge to DEST. */
2357 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2359 basic_block src = e->src;
2362 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2365 if (e->dest == dest)
2368 if (e->src != ENTRY_BLOCK_PTR
2369 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2371 df_set_bb_dirty (src);
2375 if (e->src == ENTRY_BLOCK_PTR
2376 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2379 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2380 e->src->index, dest->index);
2382 df_set_bb_dirty (e->src);
2383 redirect_edge_succ (e, dest);
2387 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2388 in the case the basic block appears to be in sequence. Avoid this
2391 if (e->flags & EDGE_FALLTHRU)
2393 /* Redirect any branch edges unified with the fallthru one. */
2394 if (JUMP_P (BB_END (src))
2395 && label_is_jump_target_p (BB_HEAD (e->dest),
2401 fprintf (dump_file, "Fallthru edge unified with branch "
2402 "%i->%i redirected to %i\n",
2403 e->src->index, e->dest->index, dest->index);
2404 e->flags &= ~EDGE_FALLTHRU;
2405 redirected = redirect_branch_edge (e, dest);
2406 gcc_assert (redirected);
2407 e->flags |= EDGE_FALLTHRU;
2408 df_set_bb_dirty (e->src);
2411 /* In case we are redirecting fallthru edge to the branch edge
2412 of conditional jump, remove it. */
2413 if (EDGE_COUNT (src->succs) == 2)
2415 /* Find the edge that is different from E. */
2416 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2419 && any_condjump_p (BB_END (src))
2420 && onlyjump_p (BB_END (src)))
2421 delete_insn (BB_END (src));
2423 ret = redirect_edge_succ_nodup (e, dest);
2425 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2426 e->src->index, e->dest->index, dest->index);
2429 ret = redirect_branch_edge (e, dest);
2431 /* We don't want simplejumps in the insn stream during cfglayout. */
2432 gcc_assert (!simplejump_p (BB_END (src)));
2434 df_set_bb_dirty (src);
2438 /* Simple wrapper as we always can redirect fallthru edges. */
2440 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2442 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2444 gcc_assert (redirected);
2448 /* Same as delete_basic_block but update cfg_layout structures. */
2451 cfg_layout_delete_block (basic_block bb)
2453 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2455 if (bb->il.rtl->header)
2457 next = BB_HEAD (bb);
2459 NEXT_INSN (prev) = bb->il.rtl->header;
2461 set_first_insn (bb->il.rtl->header);
2462 PREV_INSN (bb->il.rtl->header) = prev;
2463 insn = bb->il.rtl->header;
2464 while (NEXT_INSN (insn))
2465 insn = NEXT_INSN (insn);
2466 NEXT_INSN (insn) = next;
2467 PREV_INSN (next) = insn;
2469 next = NEXT_INSN (BB_END (bb));
2470 if (bb->il.rtl->footer)
2472 insn = bb->il.rtl->footer;
2475 if (BARRIER_P (insn))
2477 if (PREV_INSN (insn))
2478 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2480 bb->il.rtl->footer = NEXT_INSN (insn);
2481 if (NEXT_INSN (insn))
2482 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2486 insn = NEXT_INSN (insn);
2488 if (bb->il.rtl->footer)
2491 NEXT_INSN (insn) = bb->il.rtl->footer;
2492 PREV_INSN (bb->il.rtl->footer) = insn;
2493 while (NEXT_INSN (insn))
2494 insn = NEXT_INSN (insn);
2495 NEXT_INSN (insn) = next;
2497 PREV_INSN (next) = insn;
2499 set_last_insn (insn);
2502 if (bb->next_bb != EXIT_BLOCK_PTR)
2503 to = &bb->next_bb->il.rtl->header;
2505 to = &cfg_layout_function_footer;
2507 rtl_delete_block (bb);
2510 prev = NEXT_INSN (prev);
2512 prev = get_insns ();
2514 next = PREV_INSN (next);
2516 next = get_last_insn ();
2518 if (next && NEXT_INSN (next) != prev)
2520 remaints = unlink_insn_chain (prev, next);
2522 while (NEXT_INSN (insn))
2523 insn = NEXT_INSN (insn);
2524 NEXT_INSN (insn) = *to;
2526 PREV_INSN (*to) = insn;
2531 /* 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 /* This might have been an EH label that no longer has incoming
2580 EH edges. Update data structures to match. */
2581 maybe_remove_eh_handler (BB_HEAD (b));
2583 delete_insn (BB_HEAD (b));
2586 /* We should have fallthru edge in a, or we can do dummy redirection to get
2588 if (JUMP_P (BB_END (a)))
2589 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2590 gcc_assert (!JUMP_P (BB_END (a)));
2592 /* Possible line number notes should appear in between. */
2593 if (b->il.rtl->header)
2595 rtx first = BB_END (a), last;
2597 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a), a);
2598 delete_insn_chain (NEXT_INSN (first), last, false);
2599 b->il.rtl->header = NULL;
2602 /* In the case basic blocks are not adjacent, move them around. */
2603 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2605 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2607 emit_insn_after_noloc (first, BB_END (a), a);
2608 /* Skip possible DELETED_LABEL insn. */
2609 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2610 first = NEXT_INSN (first);
2611 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2613 delete_insn (first);
2615 /* Otherwise just re-associate the instructions. */
2620 for (insn = BB_HEAD (b);
2621 insn != NEXT_INSN (BB_END (b));
2622 insn = NEXT_INSN (insn))
2624 set_block_for_insn (insn, a);
2625 df_insn_change_bb (insn);
2629 /* Skip possible DELETED_LABEL insn. */
2630 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2631 insn = NEXT_INSN (insn);
2632 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2634 BB_END (a) = BB_END (b);
2638 df_bb_delete (b->index);
2640 /* Possible tablejumps and barriers should appear after the block. */
2641 if (b->il.rtl->footer)
2643 if (!a->il.rtl->footer)
2644 a->il.rtl->footer = b->il.rtl->footer;
2647 rtx last = a->il.rtl->footer;
2649 while (NEXT_INSN (last))
2650 last = NEXT_INSN (last);
2651 NEXT_INSN (last) = b->il.rtl->footer;
2652 PREV_INSN (b->il.rtl->footer) = last;
2654 b->il.rtl->footer = NULL;
2658 fprintf (dump_file, "Merged blocks %d and %d.\n",
2659 a->index, b->index);
2665 cfg_layout_split_edge (edge e)
2667 basic_block new_bb =
2668 create_basic_block (e->src != ENTRY_BLOCK_PTR
2669 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2672 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2673 redirect_edge_and_branch_force (e, new_bb);
2678 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2681 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2685 /* Return 1 if BB ends with a call, possibly followed by some
2686 instructions that must stay with the call, 0 otherwise. */
2689 rtl_block_ends_with_call_p (basic_block bb)
2691 rtx insn = BB_END (bb);
2693 while (!CALL_P (insn)
2694 && insn != BB_HEAD (bb)
2695 && keep_with_call_p (insn))
2696 insn = PREV_INSN (insn);
2697 return (CALL_P (insn));
2700 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2703 rtl_block_ends_with_condjump_p (basic_block bb)
2705 return any_condjump_p (BB_END (bb));
2708 /* Return true if we need to add fake edge to exit.
2709 Helper function for rtl_flow_call_edges_add. */
2712 need_fake_edge_p (rtx insn)
2718 && !SIBLING_CALL_P (insn)
2719 && !find_reg_note (insn, REG_NORETURN, NULL)
2720 && !CONST_OR_PURE_CALL_P (insn)))
2723 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2724 && MEM_VOLATILE_P (PATTERN (insn)))
2725 || (GET_CODE (PATTERN (insn)) == PARALLEL
2726 && asm_noperands (insn) != -1
2727 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2728 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2731 /* Add fake edges to the function exit for any non constant and non noreturn
2732 calls, volatile inline assembly in the bitmap of blocks specified by
2733 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2736 The goal is to expose cases in which entering a basic block does not imply
2737 that all subsequent instructions must be executed. */
2740 rtl_flow_call_edges_add (sbitmap blocks)
2743 int blocks_split = 0;
2744 int last_bb = last_basic_block;
2745 bool check_last_block = false;
2747 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2751 check_last_block = true;
2753 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2755 /* In the last basic block, before epilogue generation, there will be
2756 a fallthru edge to EXIT. Special care is required if the last insn
2757 of the last basic block is a call because make_edge folds duplicate
2758 edges, which would result in the fallthru edge also being marked
2759 fake, which would result in the fallthru edge being removed by
2760 remove_fake_edges, which would result in an invalid CFG.
2762 Moreover, we can't elide the outgoing fake edge, since the block
2763 profiler needs to take this into account in order to solve the minimal
2764 spanning tree in the case that the call doesn't return.
2766 Handle this by adding a dummy instruction in a new last basic block. */
2767 if (check_last_block)
2769 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2770 rtx insn = BB_END (bb);
2772 /* Back up past insns that must be kept in the same block as a call. */
2773 while (insn != BB_HEAD (bb)
2774 && keep_with_call_p (insn))
2775 insn = PREV_INSN (insn);
2777 if (need_fake_edge_p (insn))
2781 e = find_edge (bb, EXIT_BLOCK_PTR);
2784 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2785 commit_edge_insertions ();
2790 /* Now add fake edges to the function exit for any non constant
2791 calls since there is no way that we can determine if they will
2794 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
2796 basic_block bb = BASIC_BLOCK (i);
2803 if (blocks && !TEST_BIT (blocks, i))
2806 for (insn = BB_END (bb); ; insn = prev_insn)
2808 prev_insn = PREV_INSN (insn);
2809 if (need_fake_edge_p (insn))
2812 rtx split_at_insn = insn;
2814 /* Don't split the block between a call and an insn that should
2815 remain in the same block as the call. */
2817 while (split_at_insn != BB_END (bb)
2818 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2819 split_at_insn = NEXT_INSN (split_at_insn);
2821 /* The handling above of the final block before the epilogue
2822 should be enough to verify that there is no edge to the exit
2823 block in CFG already. Calling make_edge in such case would
2824 cause us to mark that edge as fake and remove it later. */
2826 #ifdef ENABLE_CHECKING
2827 if (split_at_insn == BB_END (bb))
2829 e = find_edge (bb, EXIT_BLOCK_PTR);
2830 gcc_assert (e == NULL);
2834 /* Note that the following may create a new basic block
2835 and renumber the existing basic blocks. */
2836 if (split_at_insn != BB_END (bb))
2838 e = split_block (bb, split_at_insn);
2843 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2846 if (insn == BB_HEAD (bb))
2852 verify_flow_info ();
2854 return blocks_split;
2857 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2858 the conditional branch target, SECOND_HEAD should be the fall-thru
2859 there is no need to handle this here the loop versioning code handles
2860 this. the reason for SECON_HEAD is that it is needed for condition
2861 in trees, and this should be of the same type since it is a hook. */
2863 rtl_lv_add_condition_to_bb (basic_block first_head ,
2864 basic_block second_head ATTRIBUTE_UNUSED,
2865 basic_block cond_bb, void *comp_rtx)
2867 rtx label, seq, jump;
2868 rtx op0 = XEXP ((rtx)comp_rtx, 0);
2869 rtx op1 = XEXP ((rtx)comp_rtx, 1);
2870 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
2871 enum machine_mode mode;
2874 label = block_label (first_head);
2875 mode = GET_MODE (op0);
2876 if (mode == VOIDmode)
2877 mode = GET_MODE (op1);
2880 op0 = force_operand (op0, NULL_RTX);
2881 op1 = force_operand (op1, NULL_RTX);
2882 do_compare_rtx_and_jump (op0, op1, comp, 0,
2883 mode, NULL_RTX, NULL_RTX, label);
2884 jump = get_last_insn ();
2885 JUMP_LABEL (jump) = label;
2886 LABEL_NUSES (label)++;
2890 /* Add the new cond , in the new head. */
2891 emit_insn_after(seq, BB_END(cond_bb));
2895 /* Given a block B with unconditional branch at its end, get the
2896 store the return the branch edge and the fall-thru edge in
2897 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
2899 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
2900 edge *fallthru_edge)
2902 edge e = EDGE_SUCC (b, 0);
2904 if (e->flags & EDGE_FALLTHRU)
2907 *branch_edge = EDGE_SUCC (b, 1);
2912 *fallthru_edge = EDGE_SUCC (b, 1);
2917 init_rtl_bb_info (basic_block bb)
2919 gcc_assert (!bb->il.rtl);
2920 bb->il.rtl = GGC_CNEW (struct rtl_bb_info);
2924 /* Add EXPR to the end of basic block BB. */
2927 insert_insn_end_bb_new (rtx pat, basic_block bb)
2929 rtx insn = BB_END (bb);
2933 while (NEXT_INSN (pat_end) != NULL_RTX)
2934 pat_end = NEXT_INSN (pat_end);
2936 /* If the last insn is a jump, insert EXPR in front [taking care to
2937 handle cc0, etc. properly]. Similarly we need to care trapping
2938 instructions in presence of non-call exceptions. */
2941 || (NONJUMP_INSN_P (insn)
2942 && (!single_succ_p (bb)
2943 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
2948 /* If this is a jump table, then we can't insert stuff here. Since
2949 we know the previous real insn must be the tablejump, we insert
2950 the new instruction just before the tablejump. */
2951 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
2952 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
2953 insn = prev_real_insn (insn);
2956 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
2957 if cc0 isn't set. */
2958 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
2960 insn = XEXP (note, 0);
2963 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
2964 if (maybe_cc0_setter
2965 && INSN_P (maybe_cc0_setter)
2966 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
2967 insn = maybe_cc0_setter;
2970 /* FIXME: What if something in cc0/jump uses value set in new
2972 new_insn = emit_insn_before_noloc (pat, insn, bb);
2975 /* Likewise if the last insn is a call, as will happen in the presence
2976 of exception handling. */
2977 else if (CALL_P (insn)
2978 && (!single_succ_p (bb)
2979 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
2981 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
2982 we search backward and place the instructions before the first
2983 parameter is loaded. Do this for everyone for consistency and a
2984 presumption that we'll get better code elsewhere as well. */
2986 /* Since different machines initialize their parameter registers
2987 in different orders, assume nothing. Collect the set of all
2988 parameter registers. */
2989 insn = find_first_parameter_load (insn, BB_HEAD (bb));
2991 /* If we found all the parameter loads, then we want to insert
2992 before the first parameter load.
2994 If we did not find all the parameter loads, then we might have
2995 stopped on the head of the block, which could be a CODE_LABEL.
2996 If we inserted before the CODE_LABEL, then we would be putting
2997 the insn in the wrong basic block. In that case, put the insn
2998 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
2999 while (LABEL_P (insn)
3000 || NOTE_INSN_BASIC_BLOCK_P (insn))
3001 insn = NEXT_INSN (insn);
3003 new_insn = emit_insn_before_noloc (pat, insn, bb);
3006 new_insn = emit_insn_after_noloc (pat, insn, bb);
3011 /* Returns true if it is possible to remove edge E by redirecting
3012 it to the destination of the other edge from E->src. */
3015 rtl_can_remove_branch_p (edge e)
3017 basic_block src = e->src;
3018 basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
3019 rtx insn = BB_END (src), set;
3021 /* The conditions are taken from try_redirect_by_replacing_jump. */
3022 if (target == EXIT_BLOCK_PTR)
3025 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
3028 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
3029 || BB_PARTITION (src) != BB_PARTITION (target))
3032 if (!onlyjump_p (insn)
3033 || tablejump_p (insn, NULL, NULL))
3036 set = single_set (insn);
3037 if (!set || side_effects_p (set))
3043 /* Implementation of CFG manipulation for linearized RTL. */
3044 struct cfg_hooks rtl_cfg_hooks = {
3046 rtl_verify_flow_info,
3048 rtl_create_basic_block,
3049 rtl_redirect_edge_and_branch,
3050 rtl_redirect_edge_and_branch_force,
3051 rtl_can_remove_branch_p,
3054 rtl_move_block_after,
3055 rtl_can_merge_blocks, /* can_merge_blocks_p */
3059 NULL, /* can_duplicate_block_p */
3060 NULL, /* duplicate_block */
3062 rtl_make_forwarder_block,
3063 rtl_tidy_fallthru_edge,
3064 rtl_block_ends_with_call_p,
3065 rtl_block_ends_with_condjump_p,
3066 rtl_flow_call_edges_add,
3067 NULL, /* execute_on_growing_pred */
3068 NULL, /* execute_on_shrinking_pred */
3069 NULL, /* duplicate loop for trees */
3070 NULL, /* lv_add_condition_to_bb */
3071 NULL, /* lv_adjust_loop_header_phi*/
3072 NULL, /* extract_cond_bb_edges */
3073 NULL /* flush_pending_stmts */
3076 /* Implementation of CFG manipulation for cfg layout RTL, where
3077 basic block connected via fallthru edges does not have to be adjacent.
3078 This representation will hopefully become the default one in future
3079 version of the compiler. */
3081 /* We do not want to declare these functions in a header file, since they
3082 should only be used through the cfghooks interface, and we do not want to
3083 move them here since it would require also moving quite a lot of related
3084 code. They are in cfglayout.c. */
3085 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3086 extern basic_block cfg_layout_duplicate_bb (basic_block);
3088 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3090 rtl_verify_flow_info_1,
3092 cfg_layout_create_basic_block,
3093 cfg_layout_redirect_edge_and_branch,
3094 cfg_layout_redirect_edge_and_branch_force,
3095 rtl_can_remove_branch_p,
3096 cfg_layout_delete_block,
3097 cfg_layout_split_block,
3098 rtl_move_block_after,
3099 cfg_layout_can_merge_blocks_p,
3100 cfg_layout_merge_blocks,
3103 cfg_layout_can_duplicate_bb_p,
3104 cfg_layout_duplicate_bb,
3105 cfg_layout_split_edge,
3106 rtl_make_forwarder_block,
3108 rtl_block_ends_with_call_p,
3109 rtl_block_ends_with_condjump_p,
3110 rtl_flow_call_edges_add,
3111 NULL, /* execute_on_growing_pred */
3112 NULL, /* execute_on_shrinking_pred */
3113 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3114 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3115 NULL, /* lv_adjust_loop_header_phi*/
3116 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3117 NULL /* flush_pending_stmts */