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 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
22 /* This file contains low level functions to manipulate the CFG and analyze it
23 that are aware of the RTL intermediate language.
25 Available functionality:
26 - Basic CFG/RTL manipulation API documented in cfghooks.h
27 - CFG-aware instruction chain manipulation
28 delete_insn, delete_insn_chain
29 - Edge splitting and committing to edges
30 insert_insn_on_edge, commit_edge_insertions
31 - CFG updating after insn simplification
32 purge_dead_edges, purge_all_dead_edges
34 Functions not supposed for generic use:
35 - Infrastructure to determine quickly basic block for insn
36 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
37 - Edge redirection with updating and optimizing of insn chain
38 block_label, tidy_fallthru_edge, force_nonfallthru */
42 #include "coretypes.h"
46 #include "hard-reg-set.h"
47 #include "basic-block.h"
56 #include "insn-config.h"
57 #include "cfglayout.h"
62 #include "tree-pass.h"
64 static int can_delete_note_p (rtx);
65 static int can_delete_label_p (rtx);
66 static void commit_one_edge_insertion (edge);
67 static basic_block rtl_split_edge (edge);
68 static bool rtl_move_block_after (basic_block, basic_block);
69 static int rtl_verify_flow_info (void);
70 static basic_block cfg_layout_split_block (basic_block, void *);
71 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
72 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
73 static void cfg_layout_delete_block (basic_block);
74 static void rtl_delete_block (basic_block);
75 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
76 static edge rtl_redirect_edge_and_branch (edge, basic_block);
77 static basic_block rtl_split_block (basic_block, void *);
78 static void rtl_dump_bb (basic_block, FILE *, int);
79 static int rtl_verify_flow_info_1 (void);
80 static void rtl_make_forwarder_block (edge);
82 /* Return true if NOTE is not one of the ones that must be kept paired,
83 so that we may simply delete it. */
86 can_delete_note_p (rtx note)
88 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
89 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
92 /* True if a given label can be deleted. */
95 can_delete_label_p (rtx label)
97 return (!LABEL_PRESERVE_P (label)
98 /* User declared labels must be preserved. */
99 && LABEL_NAME (label) == 0
100 && !in_expr_list_p (forced_labels, label));
103 /* Delete INSN by patching it out. Return the next insn. */
106 delete_insn (rtx insn)
108 rtx next = NEXT_INSN (insn);
110 bool really_delete = true;
114 /* Some labels can't be directly removed from the INSN chain, as they
115 might be references via variables, constant pool etc.
116 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
117 if (! can_delete_label_p (insn))
119 const char *name = LABEL_NAME (insn);
121 really_delete = false;
122 PUT_CODE (insn, NOTE);
123 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
124 NOTE_DELETED_LABEL_NAME (insn) = name;
127 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
132 /* If this insn has already been deleted, something is very wrong. */
133 gcc_assert (!INSN_DELETED_P (insn));
135 INSN_DELETED_P (insn) = 1;
138 /* If deleting a jump, decrement the use count of the label. Deleting
139 the label itself should happen in the normal course of block merging. */
142 && LABEL_P (JUMP_LABEL (insn)))
143 LABEL_NUSES (JUMP_LABEL (insn))--;
145 /* Also if deleting an insn that references a label. */
148 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
149 && LABEL_P (XEXP (note, 0)))
151 LABEL_NUSES (XEXP (note, 0))--;
152 remove_note (insn, note);
157 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
158 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
160 rtx pat = PATTERN (insn);
161 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
162 int len = XVECLEN (pat, diff_vec_p);
165 for (i = 0; i < len; i++)
167 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
169 /* When deleting code in bulk (e.g. removing many unreachable
170 blocks) we can delete a label that's a target of the vector
171 before deleting the vector itself. */
173 LABEL_NUSES (label)--;
180 /* Like delete_insn but also purge dead edges from BB. */
182 delete_insn_and_edges (rtx insn)
188 && BLOCK_FOR_INSN (insn)
189 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
191 x = delete_insn (insn);
193 purge_dead_edges (BLOCK_FOR_INSN (insn));
197 /* Unlink a chain of insns between START and FINISH, leaving notes
198 that must be paired. */
201 delete_insn_chain (rtx start, rtx finish)
205 /* Unchain the insns one by one. It would be quicker to delete all of these
206 with a single unchaining, rather than one at a time, but we need to keep
210 next = NEXT_INSN (start);
211 if (NOTE_P (start) && !can_delete_note_p (start))
214 next = delete_insn (start);
222 /* Like delete_insn but also purge dead edges from BB. */
224 delete_insn_chain_and_edges (rtx first, rtx last)
229 && BLOCK_FOR_INSN (last)
230 && BB_END (BLOCK_FOR_INSN (last)) == last)
232 delete_insn_chain (first, last);
234 purge_dead_edges (BLOCK_FOR_INSN (last));
237 /* Create a new basic block consisting of the instructions between HEAD and END
238 inclusive. This function is designed to allow fast BB construction - reuses
239 the note and basic block struct in BB_NOTE, if any and do not grow
240 BASIC_BLOCK chain and should be used directly only by CFG construction code.
241 END can be NULL in to create new empty basic block before HEAD. Both END
242 and HEAD can be NULL to create basic block at the end of INSN chain.
243 AFTER is the basic block we should be put after. */
246 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
251 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
254 /* If we found an existing note, thread it back onto the chain. */
262 after = PREV_INSN (head);
266 if (after != bb_note && NEXT_INSN (after) != bb_note)
267 reorder_insns_nobb (bb_note, bb_note, after);
271 /* Otherwise we must create a note and a basic block structure. */
275 init_rtl_bb_info (bb);
278 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
279 else if (LABEL_P (head) && end)
281 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
287 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
293 NOTE_BASIC_BLOCK (bb_note) = bb;
296 /* Always include the bb note in the block. */
297 if (NEXT_INSN (end) == bb_note)
302 bb->index = last_basic_block++;
303 bb->flags = BB_NEW | BB_RTL;
304 link_block (bb, after);
305 SET_BASIC_BLOCK (bb->index, bb);
306 update_bb_for_insn (bb);
307 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
309 /* Tag the block so that we know it has been used when considering
310 other basic block notes. */
316 /* Create new basic block consisting of instructions in between HEAD and END
317 and place it to the BB chain after block AFTER. END can be NULL in to
318 create new empty basic block before HEAD. Both END and HEAD can be NULL to
319 create basic block at the end of INSN chain. */
322 rtl_create_basic_block (void *headp, void *endp, basic_block after)
324 rtx head = headp, end = endp;
327 /* Grow the basic block array if needed. */
328 if ((size_t) last_basic_block >= VEC_length (basic_block, basic_block_info))
330 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
331 VEC_safe_grow_cleared (basic_block, gc, basic_block_info, new_size);
336 bb = create_basic_block_structure (head, end, NULL, after);
342 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
344 basic_block newbb = rtl_create_basic_block (head, end, after);
349 /* Delete the insns in a (non-live) block. We physically delete every
350 non-deleted-note insn, and update the flow graph appropriately.
352 Return nonzero if we deleted an exception handler. */
354 /* ??? Preserving all such notes strikes me as wrong. It would be nice
355 to post-process the stream to remove empty blocks, loops, ranges, etc. */
358 rtl_delete_block (basic_block b)
362 /* If the head of this block is a CODE_LABEL, then it might be the
363 label for an exception handler which can't be reached. We need
364 to remove the label from the exception_handler_label list. */
367 maybe_remove_eh_handler (insn);
369 end = get_last_bb_insn (b);
371 /* Selectively delete the entire chain. */
373 delete_insn_chain (insn, end);
374 if (b->il.rtl->global_live_at_start)
376 FREE_REG_SET (b->il.rtl->global_live_at_start);
377 FREE_REG_SET (b->il.rtl->global_live_at_end);
378 b->il.rtl->global_live_at_start = NULL;
379 b->il.rtl->global_live_at_end = NULL;
383 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
386 compute_bb_for_insn (void)
392 rtx end = BB_END (bb);
395 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
397 BLOCK_FOR_INSN (insn) = bb;
404 /* Release the basic_block_for_insn array. */
407 free_bb_for_insn (void)
410 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
411 if (!BARRIER_P (insn))
412 BLOCK_FOR_INSN (insn) = NULL;
416 struct tree_opt_pass pass_free_cfg =
420 free_bb_for_insn, /* execute */
423 0, /* static_pass_number */
425 0, /* properties_required */
426 0, /* properties_provided */
427 PROP_cfg, /* properties_destroyed */
428 0, /* todo_flags_start */
429 0, /* todo_flags_finish */
433 /* Return RTX to emit after when we want to emit code on the entry of function. */
435 entry_of_function (void)
437 return (n_basic_blocks > NUM_FIXED_BLOCKS ?
438 BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
441 /* Emit INSN at the entry point of the function, ensuring that it is only
442 executed once per function. */
444 emit_insn_at_entry (rtx insn)
446 edge_iterator ei = ei_start (ENTRY_BLOCK_PTR->succs);
447 edge e = ei_safe_edge (ei);
448 gcc_assert (e->flags & EDGE_FALLTHRU);
450 insert_insn_on_edge (insn, e);
451 commit_edge_insertions ();
454 /* Update insns block within BB. */
457 update_bb_for_insn (basic_block bb)
461 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
463 if (!BARRIER_P (insn))
464 set_block_for_insn (insn, bb);
465 if (insn == BB_END (bb))
470 /* Creates a new basic block just after basic block B by splitting
471 everything after specified instruction I. */
474 rtl_split_block (basic_block bb, void *insnp)
483 insn = first_insn_after_basic_block_note (bb);
486 insn = PREV_INSN (insn);
488 insn = get_last_insn ();
491 /* We probably should check type of the insn so that we do not create
492 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
494 if (insn == BB_END (bb))
495 emit_note_after (NOTE_INSN_DELETED, insn);
497 /* Create the new basic block. */
498 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
499 BB_COPY_PARTITION (new_bb, bb);
502 /* Redirect the outgoing edges. */
503 new_bb->succs = bb->succs;
505 FOR_EACH_EDGE (e, ei, new_bb->succs)
508 if (bb->il.rtl->global_live_at_start)
510 new_bb->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
511 new_bb->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
512 COPY_REG_SET (new_bb->il.rtl->global_live_at_end, bb->il.rtl->global_live_at_end);
514 /* We now have to calculate which registers are live at the end
515 of the split basic block and at the start of the new basic
516 block. Start with those registers that are known to be live
517 at the end of the original basic block and get
518 propagate_block to determine which registers are live. */
519 COPY_REG_SET (new_bb->il.rtl->global_live_at_start, bb->il.rtl->global_live_at_end);
520 propagate_block (new_bb, new_bb->il.rtl->global_live_at_start, NULL, NULL, 0);
521 COPY_REG_SET (bb->il.rtl->global_live_at_end,
522 new_bb->il.rtl->global_live_at_start);
523 #ifdef HAVE_conditional_execution
524 /* In the presence of conditional execution we are not able to update
525 liveness precisely. */
526 if (reload_completed)
528 bb->flags |= BB_DIRTY;
529 new_bb->flags |= BB_DIRTY;
537 /* Blocks A and B are to be merged into a single block A. The insns
538 are already contiguous. */
541 rtl_merge_blocks (basic_block a, basic_block b)
543 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
544 rtx del_first = NULL_RTX, del_last = NULL_RTX;
547 /* If there was a CODE_LABEL beginning B, delete it. */
548 if (LABEL_P (b_head))
550 /* This might have been an EH label that no longer has incoming
551 EH edges. Update data structures to match. */
552 maybe_remove_eh_handler (b_head);
554 /* Detect basic blocks with nothing but a label. This can happen
555 in particular at the end of a function. */
559 del_first = del_last = b_head;
560 b_head = NEXT_INSN (b_head);
563 /* Delete the basic block note and handle blocks containing just that
565 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
573 b_head = NEXT_INSN (b_head);
576 /* If there was a jump out of A, delete it. */
581 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
583 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
584 || prev == BB_HEAD (a))
590 /* If this was a conditional jump, we need to also delete
591 the insn that set cc0. */
592 if (only_sets_cc0_p (prev))
596 prev = prev_nonnote_insn (prev);
603 a_end = PREV_INSN (del_first);
605 else if (BARRIER_P (NEXT_INSN (a_end)))
606 del_first = NEXT_INSN (a_end);
608 /* Delete everything marked above as well as crap that might be
609 hanging out between the two blocks. */
611 delete_insn_chain (del_first, del_last);
613 /* Reassociate the insns of B with A. */
618 for (x = a_end; x != b_end; x = NEXT_INSN (x))
619 set_block_for_insn (x, a);
621 set_block_for_insn (b_end, a);
627 a->il.rtl->global_live_at_end = b->il.rtl->global_live_at_end;
630 /* Return true when block A and B can be merged. */
632 rtl_can_merge_blocks (basic_block a,basic_block b)
634 /* If we are partitioning hot/cold basic blocks, we don't want to
635 mess up unconditional or indirect jumps that cross between hot
638 Basic block partitioning may result in some jumps that appear to
639 be optimizable (or blocks that appear to be mergeable), but which really
640 must be left untouched (they are required to make it safely across
641 partition boundaries). See the comments at the top of
642 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
644 if (BB_PARTITION (a) != BB_PARTITION (b))
647 /* There must be exactly one edge in between the blocks. */
648 return (single_succ_p (a)
649 && single_succ (a) == b
652 /* Must be simple edge. */
653 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
655 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
656 /* If the jump insn has side effects,
657 we can't kill the edge. */
658 && (!JUMP_P (BB_END (a))
660 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
663 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
667 block_label (basic_block block)
669 if (block == EXIT_BLOCK_PTR)
672 if (!LABEL_P (BB_HEAD (block)))
674 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
677 return BB_HEAD (block);
680 /* Attempt to perform edge redirection by replacing possibly complex jump
681 instruction by unconditional jump or removing jump completely. This can
682 apply only if all edges now point to the same block. The parameters and
683 return values are equivalent to redirect_edge_and_branch. */
686 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
688 basic_block src = e->src;
689 rtx insn = BB_END (src), kill_from;
693 /* If we are partitioning hot/cold basic blocks, we don't want to
694 mess up unconditional or indirect jumps that cross between hot
697 Basic block partitioning may result in some jumps that appear to
698 be optimizable (or blocks that appear to be mergeable), but which really
699 must be left untouched (they are required to make it safely across
700 partition boundaries). See the comments at the top of
701 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
703 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
704 || BB_PARTITION (src) != BB_PARTITION (target))
707 /* We can replace or remove a complex jump only when we have exactly
708 two edges. Also, if we have exactly one outgoing edge, we can
710 if (EDGE_COUNT (src->succs) >= 3
711 /* Verify that all targets will be TARGET. Specifically, the
712 edge that is not E must also go to TARGET. */
713 || (EDGE_COUNT (src->succs) == 2
714 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
717 if (!onlyjump_p (insn))
719 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
722 /* Avoid removing branch with side effects. */
723 set = single_set (insn);
724 if (!set || side_effects_p (set))
727 /* In case we zap a conditional jump, we'll need to kill
728 the cc0 setter too. */
731 if (reg_mentioned_p (cc0_rtx, PATTERN (insn))
732 && only_sets_cc0_p (PREV_INSN (insn)))
733 kill_from = PREV_INSN (insn);
736 /* See if we can create the fallthru edge. */
737 if (in_cfglayout || can_fallthru (src, target))
740 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
743 /* Selectively unlink whole insn chain. */
746 rtx insn = src->il.rtl->footer;
748 delete_insn_chain (kill_from, BB_END (src));
750 /* Remove barriers but keep jumptables. */
753 if (BARRIER_P (insn))
755 if (PREV_INSN (insn))
756 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
758 src->il.rtl->footer = NEXT_INSN (insn);
759 if (NEXT_INSN (insn))
760 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
764 insn = NEXT_INSN (insn);
768 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
771 /* If this already is simplejump, redirect it. */
772 else if (simplejump_p (insn))
774 if (e->dest == target)
777 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
778 INSN_UID (insn), e->dest->index, target->index);
779 if (!redirect_jump (insn, block_label (target), 0))
781 gcc_assert (target == EXIT_BLOCK_PTR);
786 /* Cannot do anything for target exit block. */
787 else if (target == EXIT_BLOCK_PTR)
790 /* Or replace possibly complicated jump insn by simple jump insn. */
793 rtx target_label = block_label (target);
794 rtx barrier, label, table;
796 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
797 JUMP_LABEL (BB_END (src)) = target_label;
798 LABEL_NUSES (target_label)++;
800 fprintf (dump_file, "Replacing insn %i by jump %i\n",
801 INSN_UID (insn), INSN_UID (BB_END (src)));
804 delete_insn_chain (kill_from, insn);
806 /* Recognize a tablejump that we are converting to a
807 simple jump and remove its associated CODE_LABEL
808 and ADDR_VEC or ADDR_DIFF_VEC. */
809 if (tablejump_p (insn, &label, &table))
810 delete_insn_chain (label, table);
812 barrier = next_nonnote_insn (BB_END (src));
813 if (!barrier || !BARRIER_P (barrier))
814 emit_barrier_after (BB_END (src));
817 if (barrier != NEXT_INSN (BB_END (src)))
819 /* Move the jump before barrier so that the notes
820 which originally were or were created before jump table are
821 inside the basic block. */
822 rtx new_insn = BB_END (src);
825 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
826 tmp = NEXT_INSN (tmp))
827 set_block_for_insn (tmp, src);
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);
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);
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 src->flags |= BB_DIRTY;
973 ret = redirect_branch_edge (e, target);
977 src->flags |= BB_DIRTY;
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 if (target->il.rtl->global_live_at_start)
1087 jump_block->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
1088 jump_block->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
1089 COPY_REG_SET (jump_block->il.rtl->global_live_at_start,
1090 target->il.rtl->global_live_at_start);
1091 COPY_REG_SET (jump_block->il.rtl->global_live_at_end,
1092 target->il.rtl->global_live_at_start);
1095 /* Make sure new block ends up in correct hot/cold section. */
1097 BB_COPY_PARTITION (jump_block, e->src);
1098 if (flag_reorder_blocks_and_partition
1099 && targetm.have_named_sections
1100 && JUMP_P (BB_END (jump_block))
1101 && !any_condjump_p (BB_END (jump_block))
1102 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1103 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST (REG_CROSSING_JUMP,
1110 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1111 new_edge->probability = e->probability;
1112 new_edge->count = e->count;
1114 /* Redirect old edge. */
1115 redirect_edge_pred (e, jump_block);
1116 e->probability = REG_BR_PROB_BASE;
1118 new_bb = jump_block;
1121 jump_block = e->src;
1123 e->flags &= ~EDGE_FALLTHRU;
1124 if (target == EXIT_BLOCK_PTR)
1127 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1134 rtx label = block_label (target);
1135 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1136 JUMP_LABEL (BB_END (jump_block)) = label;
1137 LABEL_NUSES (label)++;
1140 emit_barrier_after (BB_END (jump_block));
1141 redirect_edge_succ_nodup (e, target);
1143 if (abnormal_edge_flags)
1144 make_edge (src, target, abnormal_edge_flags);
1149 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1150 (and possibly create new basic block) to make edge non-fallthru.
1151 Return newly created BB or NULL if none. */
1154 force_nonfallthru (edge e)
1156 return force_nonfallthru_and_redirect (e, e->dest);
1159 /* Redirect edge even at the expense of creating new jump insn or
1160 basic block. Return new basic block if created, NULL otherwise.
1161 Conversion must be possible. */
1164 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1166 if (redirect_edge_and_branch (e, target)
1167 || e->dest == target)
1170 /* In case the edge redirection failed, try to force it to be non-fallthru
1171 and redirect newly created simplejump. */
1172 e->src->flags |= BB_DIRTY;
1173 return force_nonfallthru_and_redirect (e, target);
1176 /* The given edge should potentially be a fallthru edge. If that is in
1177 fact true, delete the jump and barriers that are in the way. */
1180 rtl_tidy_fallthru_edge (edge e)
1183 basic_block b = e->src, c = b->next_bb;
1185 /* ??? In a late-running flow pass, other folks may have deleted basic
1186 blocks by nopping out blocks, leaving multiple BARRIERs between here
1187 and the target label. They ought to be chastised and fixed.
1189 We can also wind up with a sequence of undeletable labels between
1190 one block and the next.
1192 So search through a sequence of barriers, labels, and notes for
1193 the head of block C and assert that we really do fall through. */
1195 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1199 /* Remove what will soon cease being the jump insn from the source block.
1200 If block B consisted only of this single jump, turn it into a deleted
1205 && (any_uncondjump_p (q)
1206 || single_succ_p (b)))
1209 /* If this was a conditional jump, we need to also delete
1210 the insn that set cc0. */
1211 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1218 /* Selectively unlink the sequence. */
1219 if (q != PREV_INSN (BB_HEAD (c)))
1220 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1222 e->flags |= EDGE_FALLTHRU;
1225 /* Should move basic block BB after basic block AFTER. NIY. */
1228 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1229 basic_block after ATTRIBUTE_UNUSED)
1234 /* Split a (typically critical) edge. Return the new block.
1235 The edge must not be abnormal.
1237 ??? The code generally expects to be called on critical edges.
1238 The case of a block ending in an unconditional jump to a
1239 block with multiple predecessors is not handled optimally. */
1242 rtl_split_edge (edge edge_in)
1247 /* Abnormal edges cannot be split. */
1248 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1250 /* We are going to place the new block in front of edge destination.
1251 Avoid existence of fallthru predecessors. */
1252 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1257 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1258 if (e->flags & EDGE_FALLTHRU)
1262 force_nonfallthru (e);
1265 /* Create the basic block note. */
1266 if (edge_in->dest != EXIT_BLOCK_PTR)
1267 before = BB_HEAD (edge_in->dest);
1271 /* If this is a fall through edge to the exit block, the blocks might be
1272 not adjacent, and the right place is the after the source. */
1273 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1275 before = NEXT_INSN (BB_END (edge_in->src));
1276 bb = create_basic_block (before, NULL, edge_in->src);
1277 BB_COPY_PARTITION (bb, edge_in->src);
1281 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1282 /* ??? Why not edge_in->dest->prev_bb here? */
1283 BB_COPY_PARTITION (bb, edge_in->dest);
1286 /* ??? This info is likely going to be out of date very soon. */
1287 if (edge_in->dest->il.rtl->global_live_at_start)
1289 bb->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
1290 bb->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
1291 COPY_REG_SET (bb->il.rtl->global_live_at_start,
1292 edge_in->dest->il.rtl->global_live_at_start);
1293 COPY_REG_SET (bb->il.rtl->global_live_at_end,
1294 edge_in->dest->il.rtl->global_live_at_start);
1297 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1299 /* For non-fallthru edges, we must adjust the predecessor's
1300 jump instruction to target our new block. */
1301 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1303 edge redirected = redirect_edge_and_branch (edge_in, bb);
1304 gcc_assert (redirected);
1307 redirect_edge_succ (edge_in, bb);
1312 /* Queue instructions for insertion on an edge between two basic blocks.
1313 The new instructions and basic blocks (if any) will not appear in the
1314 CFG until commit_edge_insertions is called. */
1317 insert_insn_on_edge (rtx pattern, edge e)
1319 /* We cannot insert instructions on an abnormal critical edge.
1320 It will be easier to find the culprit if we die now. */
1321 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1323 if (e->insns.r == NULL_RTX)
1326 push_to_sequence (e->insns.r);
1328 emit_insn (pattern);
1330 e->insns.r = get_insns ();
1334 /* Update the CFG for the instructions queued on edge E. */
1337 commit_one_edge_insertion (edge e)
1339 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1340 basic_block bb = NULL;
1342 /* Pull the insns off the edge now since the edge might go away. */
1344 e->insns.r = NULL_RTX;
1346 if (!before && !after)
1348 /* Figure out where to put these things. If the destination has
1349 one predecessor, insert there. Except for the exit block. */
1350 if (single_pred_p (e->dest) && e->dest != EXIT_BLOCK_PTR)
1354 /* Get the location correct wrt a code label, and "nice" wrt
1355 a basic block note, and before everything else. */
1358 tmp = NEXT_INSN (tmp);
1359 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1360 tmp = NEXT_INSN (tmp);
1361 if (tmp == BB_HEAD (bb))
1364 after = PREV_INSN (tmp);
1366 after = get_last_insn ();
1369 /* If the source has one successor and the edge is not abnormal,
1370 insert there. Except for the entry block. */
1371 else if ((e->flags & EDGE_ABNORMAL) == 0
1372 && single_succ_p (e->src)
1373 && e->src != ENTRY_BLOCK_PTR)
1377 /* It is possible to have a non-simple jump here. Consider a target
1378 where some forms of unconditional jumps clobber a register. This
1379 happens on the fr30 for example.
1381 We know this block has a single successor, so we can just emit
1382 the queued insns before the jump. */
1383 if (JUMP_P (BB_END (bb)))
1384 before = BB_END (bb);
1387 /* We'd better be fallthru, or we've lost track of
1389 gcc_assert (e->flags & EDGE_FALLTHRU);
1391 after = BB_END (bb);
1394 /* Otherwise we must split the edge. */
1397 bb = split_edge (e);
1398 after = BB_END (bb);
1400 if (flag_reorder_blocks_and_partition
1401 && targetm.have_named_sections
1402 && e->src != ENTRY_BLOCK_PTR
1403 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1404 && !(e->flags & EDGE_CROSSING))
1406 rtx bb_note, cur_insn;
1409 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1410 cur_insn = NEXT_INSN (cur_insn))
1411 if (NOTE_P (cur_insn)
1412 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1418 if (JUMP_P (BB_END (bb))
1419 && !any_condjump_p (BB_END (bb))
1420 && (single_succ_edge (bb)->flags & EDGE_CROSSING))
1421 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1422 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1427 /* Now that we've found the spot, do the insertion. */
1431 emit_insn_before_noloc (insns, before);
1432 last = prev_nonnote_insn (before);
1435 last = emit_insn_after_noloc (insns, after);
1437 if (returnjump_p (last))
1439 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1440 This is not currently a problem because this only happens
1441 for the (single) epilogue, which already has a fallthru edge
1444 e = single_succ_edge (bb);
1445 gcc_assert (e->dest == EXIT_BLOCK_PTR
1446 && single_succ_p (bb) && (e->flags & EDGE_FALLTHRU));
1448 e->flags &= ~EDGE_FALLTHRU;
1449 emit_barrier_after (last);
1452 delete_insn (before);
1455 gcc_assert (!JUMP_P (last));
1457 /* Mark the basic block for find_many_sub_basic_blocks. */
1458 if (current_ir_type () != IR_RTL_CFGLAYOUT)
1462 /* Update the CFG for all queued instructions. */
1465 commit_edge_insertions (void)
1469 bool changed = false;
1471 #ifdef ENABLE_CHECKING
1472 verify_flow_info ();
1475 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1480 FOR_EACH_EDGE (e, ei, bb->succs)
1484 commit_one_edge_insertion (e);
1491 /* In the old rtl CFG API, it was OK to insert control flow on an
1492 edge, apparently? In cfglayout mode, this will *not* work, and
1493 the caller is responsible for making sure that control flow is
1494 valid at all times. */
1495 if (current_ir_type () == IR_RTL_CFGLAYOUT)
1498 blocks = sbitmap_alloc (last_basic_block);
1499 sbitmap_zero (blocks);
1503 SET_BIT (blocks, bb->index);
1504 /* Check for forgotten bb->aux values before commit_edge_insertions
1506 gcc_assert (bb->aux == &bb->aux);
1509 find_many_sub_basic_blocks (blocks);
1510 sbitmap_free (blocks);
1513 /* Print out RTL-specific basic block information (live information
1514 at start and end). */
1517 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1523 s_indent = alloca ((size_t) indent + 1);
1524 memset (s_indent, ' ', (size_t) indent);
1525 s_indent[indent] = '\0';
1527 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1528 dump_regset (bb->il.rtl->global_live_at_start, outf);
1531 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1532 insn = NEXT_INSN (insn))
1533 print_rtl_single (outf, insn);
1535 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1536 dump_regset (bb->il.rtl->global_live_at_end, outf);
1540 /* Like print_rtl, but also print out live information for the start of each
1544 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1549 fprintf (outf, "(nil)\n");
1552 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1553 int max_uid = get_max_uid ();
1554 basic_block *start = XCNEWVEC (basic_block, max_uid);
1555 basic_block *end = XCNEWVEC (basic_block, max_uid);
1556 enum bb_state *in_bb_p = XCNEWVEC (enum bb_state, max_uid);
1560 FOR_EACH_BB_REVERSE (bb)
1564 start[INSN_UID (BB_HEAD (bb))] = bb;
1565 end[INSN_UID (BB_END (bb))] = bb;
1566 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1568 enum bb_state state = IN_MULTIPLE_BB;
1570 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1572 in_bb_p[INSN_UID (x)] = state;
1574 if (x == BB_END (bb))
1579 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1585 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1587 fprintf (outf, ";; Start of basic block %d, registers live:",
1589 dump_regset (bb->il.rtl->global_live_at_start, outf);
1591 FOR_EACH_EDGE (e, ei, bb->preds)
1593 fputs (";; Pred edge ", outf);
1594 dump_edge_info (outf, e, 0);
1599 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1600 && !NOTE_P (tmp_rtx)
1601 && !BARRIER_P (tmp_rtx))
1602 fprintf (outf, ";; Insn is not within a basic block\n");
1603 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1604 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1606 did_output = print_rtl_single (outf, tmp_rtx);
1608 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1610 fprintf (outf, ";; End of basic block %d, registers live:",
1612 dump_regset (bb->il.rtl->global_live_at_end, outf);
1614 FOR_EACH_EDGE (e, ei, bb->succs)
1616 fputs (";; Succ edge ", outf);
1617 dump_edge_info (outf, e, 1);
1631 if (current_function_epilogue_delay_list != 0)
1633 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1634 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1635 tmp_rtx = XEXP (tmp_rtx, 1))
1636 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1641 update_br_prob_note (basic_block bb)
1644 if (!JUMP_P (BB_END (bb)))
1646 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1647 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1649 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1652 /* Get the last insn associated with block BB (that includes barriers and
1653 tablejumps after BB). */
1655 get_last_bb_insn (basic_block bb)
1658 rtx end = BB_END (bb);
1660 /* Include any jump table following the basic block. */
1661 if (tablejump_p (end, NULL, &tmp))
1664 /* Include any barriers that may follow the basic block. */
1665 tmp = next_nonnote_insn (end);
1666 while (tmp && BARRIER_P (tmp))
1669 tmp = next_nonnote_insn (end);
1675 /* Verify the CFG and RTL consistency common for both underlying RTL and
1678 Currently it does following checks:
1680 - overlapping of basic blocks
1681 - insns with wrong BLOCK_FOR_INSN pointers
1682 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1683 - tails of basic blocks (ensure that boundary is necessary)
1684 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1685 and NOTE_INSN_BASIC_BLOCK
1686 - verify that no fall_thru edge crosses hot/cold partition boundaries
1687 - verify that there are no pending RTL branch predictions
1689 In future it can be extended check a lot of other stuff as well
1690 (reachability of basic blocks, life information, etc. etc.). */
1693 rtl_verify_flow_info_1 (void)
1699 /* Check the general integrity of the basic blocks. */
1700 FOR_EACH_BB_REVERSE (bb)
1704 if (!(bb->flags & BB_RTL))
1706 error ("BB_RTL flag not set for block %d", bb->index);
1710 FOR_BB_INSNS (bb, insn)
1711 if (BLOCK_FOR_INSN (insn) != bb)
1713 error ("insn %d basic block pointer is %d, should be %d",
1715 BLOCK_FOR_INSN (insn) ? BLOCK_FOR_INSN (insn)->index : 0,
1721 /* Now check the basic blocks (boundaries etc.) */
1722 FOR_EACH_BB_REVERSE (bb)
1724 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1725 edge e, fallthru = NULL;
1729 if (JUMP_P (BB_END (bb))
1730 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1731 && EDGE_COUNT (bb->succs) >= 2
1732 && any_condjump_p (BB_END (bb)))
1734 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1735 && profile_status != PROFILE_ABSENT)
1737 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1738 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1742 FOR_EACH_EDGE (e, ei, bb->succs)
1744 if (e->flags & EDGE_FALLTHRU)
1746 n_fallthru++, fallthru = e;
1747 if ((e->flags & EDGE_CROSSING)
1748 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1749 && e->src != ENTRY_BLOCK_PTR
1750 && e->dest != EXIT_BLOCK_PTR))
1752 error ("fallthru edge crosses section boundary (bb %i)",
1758 if ((e->flags & ~(EDGE_DFS_BACK
1760 | EDGE_IRREDUCIBLE_LOOP
1762 | EDGE_CROSSING)) == 0)
1765 if (e->flags & EDGE_ABNORMAL_CALL)
1768 if (e->flags & EDGE_EH)
1770 else if (e->flags & EDGE_ABNORMAL)
1774 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
1775 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
1777 error ("missing REG_EH_REGION note in the end of bb %i", bb->index);
1781 && (!JUMP_P (BB_END (bb))
1782 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
1783 || any_condjump_p (BB_END (bb))))))
1785 error ("too many outgoing branch edges from bb %i", bb->index);
1788 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
1790 error ("fallthru edge after unconditional jump %i", bb->index);
1793 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
1795 error ("wrong amount of branch edges after unconditional jump %i", bb->index);
1798 if (n_branch != 1 && any_condjump_p (BB_END (bb))
1799 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
1801 error ("wrong amount of branch edges after conditional jump %i",
1805 if (n_call && !CALL_P (BB_END (bb)))
1807 error ("call edges for non-call insn in bb %i", bb->index);
1811 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
1812 && (!JUMP_P (BB_END (bb))
1813 || any_condjump_p (BB_END (bb))
1814 || any_uncondjump_p (BB_END (bb))))
1816 error ("abnormal edges for no purpose in bb %i", bb->index);
1820 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
1821 /* We may have a barrier inside a basic block before dead code
1822 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
1823 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
1826 if (! BLOCK_FOR_INSN (x))
1828 ("insn %d inside basic block %d but block_for_insn is NULL",
1829 INSN_UID (x), bb->index);
1832 ("insn %d inside basic block %d but block_for_insn is %i",
1833 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1838 /* OK pointers are correct. Now check the header of basic
1839 block. It ought to contain optional CODE_LABEL followed
1840 by NOTE_BASIC_BLOCK. */
1844 if (BB_END (bb) == x)
1846 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1854 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1856 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1861 if (BB_END (bb) == x)
1862 /* Do checks for empty blocks here. */
1865 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1867 if (NOTE_INSN_BASIC_BLOCK_P (x))
1869 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1870 INSN_UID (x), bb->index);
1874 if (x == BB_END (bb))
1877 if (control_flow_insn_p (x))
1879 error ("in basic block %d:", bb->index);
1880 fatal_insn ("flow control insn inside a basic block", x);
1889 /* Verify the CFG and RTL consistency common for both underlying RTL and
1892 Currently it does following checks:
1893 - all checks of rtl_verify_flow_info_1
1894 - test head/end pointers
1895 - check that all insns are in the basic blocks
1896 (except the switch handling code, barriers and notes)
1897 - check that all returns are followed by barriers
1898 - check that all fallthru edge points to the adjacent blocks. */
1901 rtl_verify_flow_info (void)
1904 int err = rtl_verify_flow_info_1 ();
1906 rtx last_head = get_last_insn ();
1907 basic_block *bb_info;
1909 const rtx rtx_first = get_insns ();
1910 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
1911 const int max_uid = get_max_uid ();
1913 bb_info = XCNEWVEC (basic_block, max_uid);
1915 FOR_EACH_BB_REVERSE (bb)
1919 rtx head = BB_HEAD (bb);
1920 rtx end = BB_END (bb);
1922 /* Verify the end of the basic block is in the INSN chain. */
1923 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1929 error ("end insn %d for block %d not found in the insn stream",
1930 INSN_UID (end), bb->index);
1934 /* Work backwards from the end to the head of the basic block
1935 to verify the head is in the RTL chain. */
1936 for (; x != NULL_RTX; x = PREV_INSN (x))
1938 /* While walking over the insn chain, verify insns appear
1939 in only one basic block. */
1940 if (bb_info[INSN_UID (x)] != NULL)
1942 error ("insn %d is in multiple basic blocks (%d and %d)",
1943 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1947 bb_info[INSN_UID (x)] = bb;
1954 error ("head insn %d for block %d not found in the insn stream",
1955 INSN_UID (head), bb->index);
1961 FOR_EACH_EDGE (e, ei, bb->succs)
1962 if (e->flags & EDGE_FALLTHRU)
1968 /* Ensure existence of barrier in BB with no fallthru edges. */
1969 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
1970 insn = NEXT_INSN (insn))
1973 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
1975 error ("missing barrier after block %i", bb->index);
1980 else if (e->src != ENTRY_BLOCK_PTR
1981 && e->dest != EXIT_BLOCK_PTR)
1985 if (e->src->next_bb != e->dest)
1988 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
1989 e->src->index, e->dest->index);
1993 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
1994 insn = NEXT_INSN (insn))
1995 if (BARRIER_P (insn) || INSN_P (insn))
1997 error ("verify_flow_info: Incorrect fallthru %i->%i",
1998 e->src->index, e->dest->index);
1999 fatal_insn ("wrong insn in the fallthru edge", insn);
2008 last_bb_seen = ENTRY_BLOCK_PTR;
2010 for (x = rtx_first; x; x = NEXT_INSN (x))
2012 if (NOTE_INSN_BASIC_BLOCK_P (x))
2014 bb = NOTE_BASIC_BLOCK (x);
2017 if (bb != last_bb_seen->next_bb)
2018 internal_error ("basic blocks not laid down consecutively");
2020 curr_bb = last_bb_seen = bb;
2025 switch (GET_CODE (x))
2032 /* An addr_vec is placed outside any basic block. */
2034 && JUMP_P (NEXT_INSN (x))
2035 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2036 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2039 /* But in any case, non-deletable labels can appear anywhere. */
2043 fatal_insn ("insn outside basic block", x);
2048 && returnjump_p (x) && ! condjump_p (x)
2049 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2050 fatal_insn ("return not followed by barrier", x);
2051 if (curr_bb && x == BB_END (curr_bb))
2055 if (num_bb_notes != n_basic_blocks - NUM_FIXED_BLOCKS)
2057 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2058 num_bb_notes, n_basic_blocks);
2063 /* Assume that the preceding pass has possibly eliminated jump instructions
2064 or converted the unconditional jumps. Eliminate the edges from CFG.
2065 Return true if any edges are eliminated. */
2068 purge_dead_edges (basic_block bb)
2071 rtx insn = BB_END (bb), note;
2072 bool purged = false;
2076 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2077 if (NONJUMP_INSN_P (insn)
2078 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2082 if (! may_trap_p (PATTERN (insn))
2083 || ((eqnote = find_reg_equal_equiv_note (insn))
2084 && ! may_trap_p (XEXP (eqnote, 0))))
2085 remove_note (insn, note);
2088 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2089 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2091 /* There are three types of edges we need to handle correctly here: EH
2092 edges, abnormal call EH edges, and abnormal call non-EH edges. The
2093 latter can appear when nonlocal gotos are used. */
2094 if (e->flags & EDGE_EH)
2096 if (can_throw_internal (BB_END (bb))
2097 /* If this is a call edge, verify that this is a call insn. */
2098 && (! (e->flags & EDGE_ABNORMAL_CALL)
2099 || CALL_P (BB_END (bb))))
2105 else if (e->flags & EDGE_ABNORMAL_CALL)
2107 if (CALL_P (BB_END (bb))
2108 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2109 || INTVAL (XEXP (note, 0)) >= 0))
2122 bb->flags |= BB_DIRTY;
2132 /* We do care only about conditional jumps and simplejumps. */
2133 if (!any_condjump_p (insn)
2134 && !returnjump_p (insn)
2135 && !simplejump_p (insn))
2138 /* Branch probability/prediction notes are defined only for
2139 condjumps. We've possibly turned condjump into simplejump. */
2140 if (simplejump_p (insn))
2142 note = find_reg_note (insn, REG_BR_PROB, NULL);
2144 remove_note (insn, note);
2145 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2146 remove_note (insn, note);
2149 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2151 /* Avoid abnormal flags to leak from computed jumps turned
2152 into simplejumps. */
2154 e->flags &= ~EDGE_ABNORMAL;
2156 /* See if this edge is one we should keep. */
2157 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2158 /* A conditional jump can fall through into the next
2159 block, so we should keep the edge. */
2164 else if (e->dest != EXIT_BLOCK_PTR
2165 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2166 /* If the destination block is the target of the jump,
2172 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2173 /* If the destination block is the exit block, and this
2174 instruction is a return, then keep the edge. */
2179 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2180 /* Keep the edges that correspond to exceptions thrown by
2181 this instruction and rematerialize the EDGE_ABNORMAL
2182 flag we just cleared above. */
2184 e->flags |= EDGE_ABNORMAL;
2189 /* We do not need this edge. */
2190 bb->flags |= BB_DIRTY;
2195 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2199 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2204 /* Redistribute probabilities. */
2205 if (single_succ_p (bb))
2207 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2208 single_succ_edge (bb)->count = bb->count;
2212 note = find_reg_note (insn, REG_BR_PROB, NULL);
2216 b = BRANCH_EDGE (bb);
2217 f = FALLTHRU_EDGE (bb);
2218 b->probability = INTVAL (XEXP (note, 0));
2219 f->probability = REG_BR_PROB_BASE - b->probability;
2220 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2221 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2226 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2228 /* First, there should not be any EH or ABCALL edges resulting
2229 from non-local gotos and the like. If there were, we shouldn't
2230 have created the sibcall in the first place. Second, there
2231 should of course never have been a fallthru edge. */
2232 gcc_assert (single_succ_p (bb));
2233 gcc_assert (single_succ_edge (bb)->flags
2234 == (EDGE_SIBCALL | EDGE_ABNORMAL));
2239 /* If we don't see a jump insn, we don't know exactly why the block would
2240 have been broken at this point. Look for a simple, non-fallthru edge,
2241 as these are only created by conditional branches. If we find such an
2242 edge we know that there used to be a jump here and can then safely
2243 remove all non-fallthru edges. */
2245 FOR_EACH_EDGE (e, ei, bb->succs)
2246 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2255 /* Remove all but the fake and fallthru edges. The fake edge may be
2256 the only successor for this block in the case of noreturn
2258 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2260 if (!(e->flags & (EDGE_FALLTHRU | EDGE_FAKE)))
2262 bb->flags |= BB_DIRTY;
2270 gcc_assert (single_succ_p (bb));
2272 single_succ_edge (bb)->probability = REG_BR_PROB_BASE;
2273 single_succ_edge (bb)->count = bb->count;
2276 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2281 /* Search all basic blocks for potentially dead edges and purge them. Return
2282 true if some edge has been eliminated. */
2285 purge_all_dead_edges (void)
2292 bool purged_here = purge_dead_edges (bb);
2294 purged |= purged_here;
2300 /* Same as split_block but update cfg_layout structures. */
2303 cfg_layout_split_block (basic_block bb, void *insnp)
2306 basic_block new_bb = rtl_split_block (bb, insn);
2308 new_bb->il.rtl->footer = bb->il.rtl->footer;
2309 bb->il.rtl->footer = NULL;
2315 /* Redirect Edge to DEST. */
2317 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2319 basic_block src = e->src;
2322 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2325 if (e->dest == dest)
2328 if (e->src != ENTRY_BLOCK_PTR
2329 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2331 src->flags |= BB_DIRTY;
2335 if (e->src == ENTRY_BLOCK_PTR
2336 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2339 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2340 e->src->index, dest->index);
2342 e->src->flags |= BB_DIRTY;
2343 redirect_edge_succ (e, dest);
2347 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2348 in the case the basic block appears to be in sequence. Avoid this
2351 if (e->flags & EDGE_FALLTHRU)
2353 /* Redirect any branch edges unified with the fallthru one. */
2354 if (JUMP_P (BB_END (src))
2355 && label_is_jump_target_p (BB_HEAD (e->dest),
2361 fprintf (dump_file, "Fallthru edge unified with branch "
2362 "%i->%i redirected to %i\n",
2363 e->src->index, e->dest->index, dest->index);
2364 e->flags &= ~EDGE_FALLTHRU;
2365 redirected = redirect_branch_edge (e, dest);
2366 gcc_assert (redirected);
2367 e->flags |= EDGE_FALLTHRU;
2368 e->src->flags |= BB_DIRTY;
2371 /* In case we are redirecting fallthru edge to the branch edge
2372 of conditional jump, remove it. */
2373 if (EDGE_COUNT (src->succs) == 2)
2375 /* Find the edge that is different from E. */
2376 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2379 && any_condjump_p (BB_END (src))
2380 && onlyjump_p (BB_END (src)))
2381 delete_insn (BB_END (src));
2383 ret = redirect_edge_succ_nodup (e, dest);
2385 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2386 e->src->index, e->dest->index, dest->index);
2389 ret = redirect_branch_edge (e, dest);
2391 /* We don't want simplejumps in the insn stream during cfglayout. */
2392 gcc_assert (!simplejump_p (BB_END (src)));
2394 src->flags |= BB_DIRTY;
2398 /* Simple wrapper as we always can redirect fallthru edges. */
2400 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2402 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2404 gcc_assert (redirected);
2408 /* Same as delete_basic_block but update cfg_layout structures. */
2411 cfg_layout_delete_block (basic_block bb)
2413 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2415 if (bb->il.rtl->header)
2417 next = BB_HEAD (bb);
2419 NEXT_INSN (prev) = bb->il.rtl->header;
2421 set_first_insn (bb->il.rtl->header);
2422 PREV_INSN (bb->il.rtl->header) = prev;
2423 insn = bb->il.rtl->header;
2424 while (NEXT_INSN (insn))
2425 insn = NEXT_INSN (insn);
2426 NEXT_INSN (insn) = next;
2427 PREV_INSN (next) = insn;
2429 next = NEXT_INSN (BB_END (bb));
2430 if (bb->il.rtl->footer)
2432 insn = bb->il.rtl->footer;
2435 if (BARRIER_P (insn))
2437 if (PREV_INSN (insn))
2438 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2440 bb->il.rtl->footer = NEXT_INSN (insn);
2441 if (NEXT_INSN (insn))
2442 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2446 insn = NEXT_INSN (insn);
2448 if (bb->il.rtl->footer)
2451 NEXT_INSN (insn) = bb->il.rtl->footer;
2452 PREV_INSN (bb->il.rtl->footer) = insn;
2453 while (NEXT_INSN (insn))
2454 insn = NEXT_INSN (insn);
2455 NEXT_INSN (insn) = next;
2457 PREV_INSN (next) = insn;
2459 set_last_insn (insn);
2462 if (bb->next_bb != EXIT_BLOCK_PTR)
2463 to = &bb->next_bb->il.rtl->header;
2465 to = &cfg_layout_function_footer;
2467 rtl_delete_block (bb);
2470 prev = NEXT_INSN (prev);
2472 prev = get_insns ();
2474 next = PREV_INSN (next);
2476 next = get_last_insn ();
2478 if (next && NEXT_INSN (next) != prev)
2480 remaints = unlink_insn_chain (prev, next);
2482 while (NEXT_INSN (insn))
2483 insn = NEXT_INSN (insn);
2484 NEXT_INSN (insn) = *to;
2486 PREV_INSN (*to) = insn;
2491 /* Return true when blocks A and B can be safely merged. */
2493 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2495 /* If we are partitioning hot/cold basic blocks, we don't want to
2496 mess up unconditional or indirect jumps that cross between hot
2499 Basic block partitioning may result in some jumps that appear to
2500 be optimizable (or blocks that appear to be mergeable), but which really
2501 must be left untouched (they are required to make it safely across
2502 partition boundaries). See the comments at the top of
2503 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2505 if (BB_PARTITION (a) != BB_PARTITION (b))
2508 /* There must be exactly one edge in between the blocks. */
2509 return (single_succ_p (a)
2510 && single_succ (a) == b
2511 && single_pred_p (b) == 1
2513 /* Must be simple edge. */
2514 && !(single_succ_edge (a)->flags & EDGE_COMPLEX)
2515 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2516 /* If the jump insn has side effects, we can't kill the edge.
2517 When not optimizing, try_redirect_by_replacing_jump will
2518 not allow us to redirect an edge by replacing a table jump. */
2519 && (!JUMP_P (BB_END (a))
2520 || ((!optimize || reload_completed)
2521 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2524 /* Merge block A and B. The blocks must be mergeable. */
2527 cfg_layout_merge_blocks (basic_block a, basic_block b)
2529 #ifdef ENABLE_CHECKING
2530 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2533 /* If there was a CODE_LABEL beginning B, delete it. */
2534 if (LABEL_P (BB_HEAD (b)))
2536 /* This might have been an EH label that no longer has incoming
2537 EH edges. Update data structures to match. */
2538 maybe_remove_eh_handler (BB_HEAD (b));
2540 delete_insn (BB_HEAD (b));
2543 /* We should have fallthru edge in a, or we can do dummy redirection to get
2545 if (JUMP_P (BB_END (a)))
2546 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2547 gcc_assert (!JUMP_P (BB_END (a)));
2549 /* Possible line number notes should appear in between. */
2550 if (b->il.rtl->header)
2552 rtx first = BB_END (a), last;
2554 last = emit_insn_after_noloc (b->il.rtl->header, BB_END (a));
2555 delete_insn_chain (NEXT_INSN (first), last);
2556 b->il.rtl->header = NULL;
2559 /* In the case basic blocks are not adjacent, move them around. */
2560 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2562 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2564 emit_insn_after_noloc (first, BB_END (a));
2565 /* Skip possible DELETED_LABEL insn. */
2566 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2567 first = NEXT_INSN (first);
2568 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2570 delete_insn (first);
2572 /* Otherwise just re-associate the instructions. */
2577 for (insn = BB_HEAD (b);
2578 insn != NEXT_INSN (BB_END (b));
2579 insn = NEXT_INSN (insn))
2580 set_block_for_insn (insn, a);
2582 /* Skip possible DELETED_LABEL insn. */
2583 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2584 insn = NEXT_INSN (insn);
2585 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2587 BB_END (a) = BB_END (b);
2591 /* Possible tablejumps and barriers should appear after the block. */
2592 if (b->il.rtl->footer)
2594 if (!a->il.rtl->footer)
2595 a->il.rtl->footer = b->il.rtl->footer;
2598 rtx last = a->il.rtl->footer;
2600 while (NEXT_INSN (last))
2601 last = NEXT_INSN (last);
2602 NEXT_INSN (last) = b->il.rtl->footer;
2603 PREV_INSN (b->il.rtl->footer) = last;
2605 b->il.rtl->footer = NULL;
2607 a->il.rtl->global_live_at_end = b->il.rtl->global_live_at_end;
2610 fprintf (dump_file, "Merged blocks %d and %d.\n",
2611 a->index, b->index);
2617 cfg_layout_split_edge (edge e)
2619 basic_block new_bb =
2620 create_basic_block (e->src != ENTRY_BLOCK_PTR
2621 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2624 /* ??? This info is likely going to be out of date very soon, but we must
2625 create it to avoid getting an ICE later. */
2626 if (e->dest->il.rtl->global_live_at_start)
2628 new_bb->il.rtl->global_live_at_start = ALLOC_REG_SET (®_obstack);
2629 new_bb->il.rtl->global_live_at_end = ALLOC_REG_SET (®_obstack);
2630 COPY_REG_SET (new_bb->il.rtl->global_live_at_start,
2631 e->dest->il.rtl->global_live_at_start);
2632 COPY_REG_SET (new_bb->il.rtl->global_live_at_end,
2633 e->dest->il.rtl->global_live_at_start);
2636 make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2637 redirect_edge_and_branch_force (e, new_bb);
2642 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2645 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2649 /* Return 1 if BB ends with a call, possibly followed by some
2650 instructions that must stay with the call, 0 otherwise. */
2653 rtl_block_ends_with_call_p (basic_block bb)
2655 rtx insn = BB_END (bb);
2657 while (!CALL_P (insn)
2658 && insn != BB_HEAD (bb)
2659 && keep_with_call_p (insn))
2660 insn = PREV_INSN (insn);
2661 return (CALL_P (insn));
2664 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2667 rtl_block_ends_with_condjump_p (basic_block bb)
2669 return any_condjump_p (BB_END (bb));
2672 /* Return true if we need to add fake edge to exit.
2673 Helper function for rtl_flow_call_edges_add. */
2676 need_fake_edge_p (rtx insn)
2682 && !SIBLING_CALL_P (insn)
2683 && !find_reg_note (insn, REG_NORETURN, NULL)
2684 && !CONST_OR_PURE_CALL_P (insn)))
2687 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2688 && MEM_VOLATILE_P (PATTERN (insn)))
2689 || (GET_CODE (PATTERN (insn)) == PARALLEL
2690 && asm_noperands (insn) != -1
2691 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2692 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2695 /* Add fake edges to the function exit for any non constant and non noreturn
2696 calls, volatile inline assembly in the bitmap of blocks specified by
2697 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2700 The goal is to expose cases in which entering a basic block does not imply
2701 that all subsequent instructions must be executed. */
2704 rtl_flow_call_edges_add (sbitmap blocks)
2707 int blocks_split = 0;
2708 int last_bb = last_basic_block;
2709 bool check_last_block = false;
2711 if (n_basic_blocks == NUM_FIXED_BLOCKS)
2715 check_last_block = true;
2717 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2719 /* In the last basic block, before epilogue generation, there will be
2720 a fallthru edge to EXIT. Special care is required if the last insn
2721 of the last basic block is a call because make_edge folds duplicate
2722 edges, which would result in the fallthru edge also being marked
2723 fake, which would result in the fallthru edge being removed by
2724 remove_fake_edges, which would result in an invalid CFG.
2726 Moreover, we can't elide the outgoing fake edge, since the block
2727 profiler needs to take this into account in order to solve the minimal
2728 spanning tree in the case that the call doesn't return.
2730 Handle this by adding a dummy instruction in a new last basic block. */
2731 if (check_last_block)
2733 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2734 rtx insn = BB_END (bb);
2736 /* Back up past insns that must be kept in the same block as a call. */
2737 while (insn != BB_HEAD (bb)
2738 && keep_with_call_p (insn))
2739 insn = PREV_INSN (insn);
2741 if (need_fake_edge_p (insn))
2745 e = find_edge (bb, EXIT_BLOCK_PTR);
2748 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2749 commit_edge_insertions ();
2754 /* Now add fake edges to the function exit for any non constant
2755 calls since there is no way that we can determine if they will
2758 for (i = NUM_FIXED_BLOCKS; i < last_bb; i++)
2760 basic_block bb = BASIC_BLOCK (i);
2767 if (blocks && !TEST_BIT (blocks, i))
2770 for (insn = BB_END (bb); ; insn = prev_insn)
2772 prev_insn = PREV_INSN (insn);
2773 if (need_fake_edge_p (insn))
2776 rtx split_at_insn = insn;
2778 /* Don't split the block between a call and an insn that should
2779 remain in the same block as the call. */
2781 while (split_at_insn != BB_END (bb)
2782 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2783 split_at_insn = NEXT_INSN (split_at_insn);
2785 /* The handling above of the final block before the epilogue
2786 should be enough to verify that there is no edge to the exit
2787 block in CFG already. Calling make_edge in such case would
2788 cause us to mark that edge as fake and remove it later. */
2790 #ifdef ENABLE_CHECKING
2791 if (split_at_insn == BB_END (bb))
2793 e = find_edge (bb, EXIT_BLOCK_PTR);
2794 gcc_assert (e == NULL);
2798 /* Note that the following may create a new basic block
2799 and renumber the existing basic blocks. */
2800 if (split_at_insn != BB_END (bb))
2802 e = split_block (bb, split_at_insn);
2807 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
2810 if (insn == BB_HEAD (bb))
2816 verify_flow_info ();
2818 return blocks_split;
2821 /* Add COMP_RTX as a condition at end of COND_BB. FIRST_HEAD is
2822 the conditional branch target, SECOND_HEAD should be the fall-thru
2823 there is no need to handle this here the loop versioning code handles
2824 this. the reason for SECON_HEAD is that it is needed for condition
2825 in trees, and this should be of the same type since it is a hook. */
2827 rtl_lv_add_condition_to_bb (basic_block first_head ,
2828 basic_block second_head ATTRIBUTE_UNUSED,
2829 basic_block cond_bb, void *comp_rtx)
2831 rtx label, seq, jump;
2832 rtx op0 = XEXP ((rtx)comp_rtx, 0);
2833 rtx op1 = XEXP ((rtx)comp_rtx, 1);
2834 enum rtx_code comp = GET_CODE ((rtx)comp_rtx);
2835 enum machine_mode mode;
2838 label = block_label (first_head);
2839 mode = GET_MODE (op0);
2840 if (mode == VOIDmode)
2841 mode = GET_MODE (op1);
2844 op0 = force_operand (op0, NULL_RTX);
2845 op1 = force_operand (op1, NULL_RTX);
2846 do_compare_rtx_and_jump (op0, op1, comp, 0,
2847 mode, NULL_RTX, NULL_RTX, label);
2848 jump = get_last_insn ();
2849 JUMP_LABEL (jump) = label;
2850 LABEL_NUSES (label)++;
2854 /* Add the new cond , in the new head. */
2855 emit_insn_after(seq, BB_END(cond_bb));
2859 /* Given a block B with unconditional branch at its end, get the
2860 store the return the branch edge and the fall-thru edge in
2861 BRANCH_EDGE and FALLTHRU_EDGE respectively. */
2863 rtl_extract_cond_bb_edges (basic_block b, edge *branch_edge,
2864 edge *fallthru_edge)
2866 edge e = EDGE_SUCC (b, 0);
2868 if (e->flags & EDGE_FALLTHRU)
2871 *branch_edge = EDGE_SUCC (b, 1);
2876 *fallthru_edge = EDGE_SUCC (b, 1);
2881 init_rtl_bb_info (basic_block bb)
2883 gcc_assert (!bb->il.rtl);
2884 bb->il.rtl = ggc_alloc_cleared (sizeof (struct rtl_bb_info));
2888 /* Add EXPR to the end of basic block BB. */
2891 insert_insn_end_bb_new (rtx pat, basic_block bb)
2893 rtx insn = BB_END (bb);
2897 while (NEXT_INSN (pat_end) != NULL_RTX)
2898 pat_end = NEXT_INSN (pat_end);
2900 /* If the last insn is a jump, insert EXPR in front [taking care to
2901 handle cc0, etc. properly]. Similarly we need to care trapping
2902 instructions in presence of non-call exceptions. */
2905 || (NONJUMP_INSN_P (insn)
2906 && (!single_succ_p (bb)
2907 || single_succ_edge (bb)->flags & EDGE_ABNORMAL)))
2912 /* If this is a jump table, then we can't insert stuff here. Since
2913 we know the previous real insn must be the tablejump, we insert
2914 the new instruction just before the tablejump. */
2915 if (GET_CODE (PATTERN (insn)) == ADDR_VEC
2916 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC)
2917 insn = prev_real_insn (insn);
2920 /* FIXME: 'twould be nice to call prev_cc0_setter here but it aborts
2921 if cc0 isn't set. */
2922 note = find_reg_note (insn, REG_CC_SETTER, NULL_RTX);
2924 insn = XEXP (note, 0);
2927 rtx maybe_cc0_setter = prev_nonnote_insn (insn);
2928 if (maybe_cc0_setter
2929 && INSN_P (maybe_cc0_setter)
2930 && sets_cc0_p (PATTERN (maybe_cc0_setter)))
2931 insn = maybe_cc0_setter;
2934 /* FIXME: What if something in cc0/jump uses value set in new
2936 new_insn = emit_insn_before_noloc (pat, insn);
2939 /* Likewise if the last insn is a call, as will happen in the presence
2940 of exception handling. */
2941 else if (CALL_P (insn)
2942 && (!single_succ_p (bb)
2943 || single_succ_edge (bb)->flags & EDGE_ABNORMAL))
2945 /* Keeping in mind SMALL_REGISTER_CLASSES and parameters in registers,
2946 we search backward and place the instructions before the first
2947 parameter is loaded. Do this for everyone for consistency and a
2948 presumption that we'll get better code elsewhere as well. */
2950 /* Since different machines initialize their parameter registers
2951 in different orders, assume nothing. Collect the set of all
2952 parameter registers. */
2953 insn = find_first_parameter_load (insn, BB_HEAD (bb));
2955 /* If we found all the parameter loads, then we want to insert
2956 before the first parameter load.
2958 If we did not find all the parameter loads, then we might have
2959 stopped on the head of the block, which could be a CODE_LABEL.
2960 If we inserted before the CODE_LABEL, then we would be putting
2961 the insn in the wrong basic block. In that case, put the insn
2962 after the CODE_LABEL. Also, respect NOTE_INSN_BASIC_BLOCK. */
2963 while (LABEL_P (insn)
2964 || NOTE_INSN_BASIC_BLOCK_P (insn))
2965 insn = NEXT_INSN (insn);
2967 new_insn = emit_insn_before_noloc (pat, insn);
2970 new_insn = emit_insn_after_noloc (pat, insn);
2975 /* Returns true if it is possible to remove edge E by redirecting
2976 it to the destination of the other edge from E->src. */
2979 rtl_can_remove_branch_p (edge e)
2981 basic_block src = e->src;
2982 basic_block target = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest;
2983 rtx insn = BB_END (src), set;
2985 /* The conditions are taken from try_redirect_by_replacing_jump. */
2986 if (target == EXIT_BLOCK_PTR)
2989 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2992 if (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
2993 || BB_PARTITION (src) != BB_PARTITION (target))
2996 if (!onlyjump_p (insn)
2997 || tablejump_p (insn, NULL, NULL))
3000 set = single_set (insn);
3001 if (!set || side_effects_p (set))
3007 /* Implementation of CFG manipulation for linearized RTL. */
3008 struct cfg_hooks rtl_cfg_hooks = {
3010 rtl_verify_flow_info,
3012 rtl_create_basic_block,
3013 rtl_redirect_edge_and_branch,
3014 rtl_redirect_edge_and_branch_force,
3015 rtl_can_remove_branch_p,
3018 rtl_move_block_after,
3019 rtl_can_merge_blocks, /* can_merge_blocks_p */
3023 NULL, /* can_duplicate_block_p */
3024 NULL, /* duplicate_block */
3026 rtl_make_forwarder_block,
3027 rtl_tidy_fallthru_edge,
3028 rtl_block_ends_with_call_p,
3029 rtl_block_ends_with_condjump_p,
3030 rtl_flow_call_edges_add,
3031 NULL, /* execute_on_growing_pred */
3032 NULL, /* execute_on_shrinking_pred */
3033 NULL, /* duplicate loop for trees */
3034 NULL, /* lv_add_condition_to_bb */
3035 NULL, /* lv_adjust_loop_header_phi*/
3036 NULL, /* extract_cond_bb_edges */
3037 NULL /* flush_pending_stmts */
3040 /* Implementation of CFG manipulation for cfg layout RTL, where
3041 basic block connected via fallthru edges does not have to be adjacent.
3042 This representation will hopefully become the default one in future
3043 version of the compiler. */
3045 /* We do not want to declare these functions in a header file, since they
3046 should only be used through the cfghooks interface, and we do not want to
3047 move them here since it would require also moving quite a lot of related
3049 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3050 extern basic_block cfg_layout_duplicate_bb (basic_block);
3052 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3054 rtl_verify_flow_info_1,
3056 cfg_layout_create_basic_block,
3057 cfg_layout_redirect_edge_and_branch,
3058 cfg_layout_redirect_edge_and_branch_force,
3059 rtl_can_remove_branch_p,
3060 cfg_layout_delete_block,
3061 cfg_layout_split_block,
3062 rtl_move_block_after,
3063 cfg_layout_can_merge_blocks_p,
3064 cfg_layout_merge_blocks,
3067 cfg_layout_can_duplicate_bb_p,
3068 cfg_layout_duplicate_bb,
3069 cfg_layout_split_edge,
3070 rtl_make_forwarder_block,
3072 rtl_block_ends_with_call_p,
3073 rtl_block_ends_with_condjump_p,
3074 rtl_flow_call_edges_add,
3075 NULL, /* execute_on_growing_pred */
3076 NULL, /* execute_on_shrinking_pred */
3077 duplicate_loop_to_header_edge, /* duplicate loop for trees */
3078 rtl_lv_add_condition_to_bb, /* lv_add_condition_to_bb */
3079 NULL, /* lv_adjust_loop_header_phi*/
3080 rtl_extract_cond_bb_edges, /* extract_cond_bb_edges */
3081 NULL /* flush_pending_stmts */