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 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
22 /* This file contains low level functions to manipulate the CFG and analyze it
23 that are aware of the RTL intermediate language.
25 Available functionality:
26 - CFG-aware instruction chain manipulation
27 delete_insn, delete_insn_chain
28 - Basic block manipulation
29 create_basic_block, flow_delete_block, split_block,
31 - Infrastructure to determine quickly basic block for insn
32 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
33 - Edge redirection with updating and optimizing of insn chain
34 block_label, redirect_edge_and_branch,
35 redirect_edge_and_branch_force, tidy_fallthru_edge, force_nonfallthru
36 - Edge splitting and commiting to edges
37 split_edge, insert_insn_on_edge, commit_edge_insertions
38 - Dumping and debugging
39 print_rtl_with_bb, dump_bb, debug_bb, debug_bb_n
40 - Consistency checking
42 - CFG updating after constant propagation
43 purge_dead_edges, purge_all_dead_edges */
49 #include "hard-reg-set.h"
50 #include "basic-block.h"
59 #include "insn-config.h"
61 /* Stubs in case we don't have a return insn. */
64 #define gen_return() NULL_RTX
67 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
68 /* ??? Should probably be using LABEL_NUSES instead. It would take a
69 bit of surgery to be able to use or co-opt the routines in jump. */
71 rtx tail_recursion_label_list;
73 static int can_delete_note_p PARAMS ((rtx));
74 static int can_delete_label_p PARAMS ((rtx));
75 static void commit_one_edge_insertion PARAMS ((edge, int));
76 static bool try_redirect_by_replacing_jump PARAMS ((edge, basic_block));
77 static rtx last_loop_beg_note PARAMS ((rtx));
78 static bool back_edge_of_syntactic_loop_p PARAMS ((basic_block, basic_block));
79 static basic_block force_nonfallthru_and_redirect PARAMS ((edge, basic_block));
81 /* Return true if NOTE is not one of the ones that must be kept paired,
82 so that we may simply delete it. */
85 can_delete_note_p (note)
88 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
89 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK
90 || NOTE_LINE_NUMBER (note) == NOTE_INSN_PREDICTION);
93 /* True if a given label can be deleted. */
96 can_delete_label_p (label)
99 return (!LABEL_PRESERVE_P (label)
100 /* User declared labels must be preserved. */
101 && LABEL_NAME (label) == 0
102 && !in_expr_list_p (forced_labels, label)
103 && !in_expr_list_p (label_value_list, label));
106 /* Delete INSN by patching it out. Return the next insn. */
112 rtx next = NEXT_INSN (insn);
114 bool really_delete = true;
116 if (GET_CODE (insn) == CODE_LABEL)
118 /* Some labels can't be directly removed from the INSN chain, as they
119 might be references via variables, constant pool etc.
120 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
121 if (! can_delete_label_p (insn))
123 const char *name = LABEL_NAME (insn);
125 really_delete = false;
126 PUT_CODE (insn, NOTE);
127 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
128 NOTE_SOURCE_FILE (insn) = name;
131 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
136 /* If this insn has already been deleted, something is very wrong. */
137 if (INSN_DELETED_P (insn))
140 INSN_DELETED_P (insn) = 1;
143 /* If deleting a jump, decrement the use count of the label. Deleting
144 the label itself should happen in the normal course of block merging. */
145 if (GET_CODE (insn) == JUMP_INSN
147 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
148 LABEL_NUSES (JUMP_LABEL (insn))--;
150 /* Also if deleting an insn that references a label. */
151 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
152 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
153 LABEL_NUSES (XEXP (note, 0))--;
155 if (GET_CODE (insn) == JUMP_INSN
156 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
157 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
159 rtx pat = PATTERN (insn);
160 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
161 int len = XVECLEN (pat, diff_vec_p);
164 for (i = 0; i < len; i++)
166 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
168 /* When deleting code in bulk (e.g. removing many unreachable
169 blocks) we can delete a label that's a target of the vector
170 before deleting the vector itself. */
171 if (GET_CODE (label) != NOTE)
172 LABEL_NUSES (label)--;
179 /* Like delete_insn but also purge dead edges from BB. */
181 delete_insn_and_edges (insn)
188 && BLOCK_FOR_INSN (insn)
189 && BLOCK_FOR_INSN (insn)->end == 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 (start, finish)
206 /* Unchain the insns one by one. It would be quicker to delete all of these
207 with a single unchaining, rather than one at a time, but we need to keep
211 next = NEXT_INSN (start);
212 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
215 next = delete_insn (start);
223 /* Like delete_insn but also purge dead edges from BB. */
225 delete_insn_chain_and_edges (first, last)
231 && BLOCK_FOR_INSN (last)
232 && BLOCK_FOR_INSN (last)->end == last)
234 delete_insn_chain (first, last);
236 purge_dead_edges (BLOCK_FOR_INSN (last));
239 /* Create a new basic block consisting of the instructions between HEAD and END
240 inclusive. This function is designed to allow fast BB construction - reuses
241 the note and basic block struct in BB_NOTE, if any and do not grow
242 BASIC_BLOCK chain and should be used directly only by CFG construction code.
243 END can be NULL in to create new empty basic block before HEAD. Both END
244 and HEAD can be NULL to create basic block at the end of INSN chain.
245 AFTER is the basic block we should be put after. */
248 create_basic_block_structure (head, end, bb_note, after)
249 rtx head, end, bb_note;
255 && ! RTX_INTEGRATED_P (bb_note)
256 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
259 /* If we found an existing note, thread it back onto the chain. */
263 if (GET_CODE (head) == CODE_LABEL)
267 after = PREV_INSN (head);
271 if (after != bb_note && NEXT_INSN (after) != bb_note)
272 reorder_insns_nobb (bb_note, bb_note, after);
276 /* Otherwise we must create a note and a basic block structure. */
282 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
283 else if (GET_CODE (head) == CODE_LABEL && end)
285 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
291 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
297 NOTE_BASIC_BLOCK (bb_note) = bb;
300 /* Always include the bb note in the block. */
301 if (NEXT_INSN (end) == bb_note)
306 bb->index = last_basic_block++;
308 link_block (bb, after);
309 BASIC_BLOCK (bb->index) = bb;
310 update_bb_for_insn (bb);
312 /* Tag the block so that we know it has been used when considering
313 other basic block notes. */
319 /* Create new basic block consisting of instructions in between HEAD and END
320 and place it to the BB chain after block AFTER. END can be NULL in to
321 create new empty basic block before HEAD. Both END and HEAD can be NULL to
322 create basic block at the end of INSN chain. */
325 create_basic_block (head, end, after)
331 /* Place the new block just after the end. */
332 VARRAY_GROW (basic_block_info, last_basic_block+1);
336 bb = create_basic_block_structure (head, end, NULL, after);
341 /* Delete the insns in a (non-live) block. We physically delete every
342 non-deleted-note insn, and update the flow graph appropriately.
344 Return nonzero if we deleted an exception handler. */
346 /* ??? Preserving all such notes strikes me as wrong. It would be nice
347 to post-process the stream to remove empty blocks, loops, ranges, etc. */
350 flow_delete_block_noexpunge (b)
353 int deleted_handler = 0;
356 /* If the head of this block is a CODE_LABEL, then it might be the
357 label for an exception handler which can't be reached.
359 We need to remove the label from the exception_handler_label list
360 and remove the associated NOTE_INSN_EH_REGION_BEG and
361 NOTE_INSN_EH_REGION_END notes. */
363 /* Get rid of all NOTE_INSN_PREDICTIONs and NOTE_INSN_LOOP_CONTs
364 hanging before the block. */
366 for (insn = PREV_INSN (b->head); insn; insn = PREV_INSN (insn))
368 if (GET_CODE (insn) != NOTE)
370 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_PREDICTION
371 || NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_CONT)
372 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED;
377 never_reached_warning (insn, b->end);
379 if (GET_CODE (insn) == CODE_LABEL)
380 maybe_remove_eh_handler (insn);
382 /* Include any jump table following the basic block. */
384 if (GET_CODE (end) == JUMP_INSN
385 && (tmp = JUMP_LABEL (end)) != NULL_RTX
386 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
387 && GET_CODE (tmp) == JUMP_INSN
388 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
389 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
392 /* Include any barrier that may follow the basic block. */
393 tmp = next_nonnote_insn (end);
394 if (tmp && GET_CODE (tmp) == BARRIER)
397 /* Selectively delete the entire chain. */
399 delete_insn_chain (insn, end);
401 /* Remove the edges into and out of this block. Note that there may
402 indeed be edges in, if we are removing an unreachable loop. */
403 while (b->pred != NULL)
404 remove_edge (b->pred);
405 while (b->succ != NULL)
406 remove_edge (b->succ);
411 return deleted_handler;
415 flow_delete_block (b)
418 int deleted_handler = flow_delete_block_noexpunge (b);
420 /* Remove the basic block from the array. */
423 return deleted_handler;
426 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
429 compute_bb_for_insn ()
438 for (insn = bb->head; ; insn = NEXT_INSN (insn))
440 BLOCK_FOR_INSN (insn) = bb;
447 /* Release the basic_block_for_insn array. */
453 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
454 if (GET_CODE (insn) != BARRIER)
455 BLOCK_FOR_INSN (insn) = NULL;
458 /* Update insns block within BB. */
461 update_bb_for_insn (bb)
466 for (insn = bb->head; ; insn = NEXT_INSN (insn))
468 set_block_for_insn (insn, bb);
474 /* Split a block BB after insn INSN creating a new fallthru edge.
475 Return the new edge. Note that to keep other parts of the compiler happy,
476 this function renumbers all the basic blocks so that the new
477 one has a number one greater than the block split. */
480 split_block (bb, insn)
488 /* There is no point splitting the block after its end. */
492 /* Create the new basic block. */
493 new_bb = create_basic_block (NEXT_INSN (insn), bb->end, bb);
494 new_bb->count = bb->count;
495 new_bb->frequency = bb->frequency;
496 new_bb->loop_depth = bb->loop_depth;
499 /* Redirect the outgoing edges. */
500 new_bb->succ = bb->succ;
502 for (e = new_bb->succ; e; e = e->succ_next)
505 new_edge = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU);
507 if (bb->global_live_at_start)
509 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
510 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
511 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
513 /* We now have to calculate which registers are live at the end
514 of the split basic block and at the start of the new basic
515 block. Start with those registers that are known to be live
516 at the end of the original basic block and get
517 propagate_block to determine which registers are live. */
518 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
519 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
520 COPY_REG_SET (bb->global_live_at_end,
521 new_bb->global_live_at_start);
522 #ifdef HAVE_conditional_execution
523 /* In the presence of conditional execution we are not able to update
524 liveness precisely. */
525 if (reload_completed)
527 bb->flags |= BB_DIRTY;
528 new_bb->flags |= BB_DIRTY;
536 /* Blocks A and B are to be merged into a single block A. The insns
537 are already contiguous, hence `nomove'. */
540 merge_blocks_nomove (a, b)
543 rtx b_head = b->head, b_end = b->end, a_end = a->end;
544 rtx del_first = NULL_RTX, del_last = NULL_RTX;
548 /* If there was a CODE_LABEL beginning B, delete it. */
549 if (GET_CODE (b_head) == CODE_LABEL)
551 /* Detect basic blocks with nothing but a label. This can happen
552 in particular at the end of a function. */
556 del_first = del_last = b_head;
557 b_head = NEXT_INSN (b_head);
560 /* Delete the basic block note and handle blocks containing just that
562 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
570 b_head = NEXT_INSN (b_head);
573 /* If there was a jump out of A, delete it. */
574 if (GET_CODE (a_end) == JUMP_INSN)
578 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
579 if (GET_CODE (prev) != NOTE
580 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
587 /* If this was a conditional jump, we need to also delete
588 the insn that set cc0. */
589 if (only_sets_cc0_p (prev))
593 prev = prev_nonnote_insn (prev);
600 a_end = PREV_INSN (del_first);
602 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
603 del_first = NEXT_INSN (a_end);
605 /* Normally there should only be one successor of A and that is B, but
606 partway though the merge of blocks for conditional_execution we'll
607 be merging a TEST block with THEN and ELSE successors. Free the
608 whole lot of them and hope the caller knows what they're doing. */
610 remove_edge (a->succ);
612 /* Adjust the edges out of B for the new owner. */
613 for (e = b->succ; e; e = e->succ_next)
616 a->flags |= b->flags;
618 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
619 b->pred = b->succ = NULL;
620 a->global_live_at_end = b->global_live_at_end;
624 /* Delete everything marked above as well as crap that might be
625 hanging out between the two blocks. */
626 delete_insn_chain (del_first, del_last);
628 /* Reassociate the insns of B with A. */
633 for (x = a_end; x != b_end; x = NEXT_INSN (x))
634 set_block_for_insn (x, a);
636 set_block_for_insn (b_end, a);
644 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
651 if (block == EXIT_BLOCK_PTR)
654 if (GET_CODE (block->head) != CODE_LABEL)
656 block->head = emit_label_before (gen_label_rtx (), block->head);
662 /* Attempt to perform edge redirection by replacing possibly complex jump
663 instruction by unconditional jump or removing jump completely. This can
664 apply only if all edges now point to the same block. The parameters and
665 return values are equivalent to redirect_edge_and_branch. */
668 try_redirect_by_replacing_jump (e, target)
672 basic_block src = e->src;
673 rtx insn = src->end, kill_from;
678 /* Verify that all targets will be TARGET. */
679 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
680 if (tmp->dest != target && tmp != e)
683 if (tmp || !onlyjump_p (insn))
685 if (reload_completed && JUMP_LABEL (insn)
686 && (table = NEXT_INSN (JUMP_LABEL (insn))) != NULL_RTX
687 && GET_CODE (table) == JUMP_INSN
688 && (GET_CODE (PATTERN (table)) == ADDR_VEC
689 || GET_CODE (PATTERN (table)) == ADDR_DIFF_VEC))
692 /* Avoid removing branch with side effects. */
693 set = single_set (insn);
694 if (!set || side_effects_p (set))
697 /* In case we zap a conditional jump, we'll need to kill
698 the cc0 setter too. */
701 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
702 kill_from = PREV_INSN (insn);
705 /* See if we can create the fallthru edge. */
706 if (can_fallthru (src, target))
709 fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn));
712 /* Selectively unlink whole insn chain. */
713 delete_insn_chain (kill_from, PREV_INSN (target->head));
716 /* If this already is simplejump, redirect it. */
717 else if (simplejump_p (insn))
719 if (e->dest == target)
722 fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n",
723 INSN_UID (insn), e->dest->index, target->index);
724 if (!redirect_jump (insn, block_label (target), 0))
726 if (target == EXIT_BLOCK_PTR)
732 /* Cannot do anything for target exit block. */
733 else if (target == EXIT_BLOCK_PTR)
736 /* Or replace possibly complicated jump insn by simple jump insn. */
739 rtx target_label = block_label (target);
742 emit_jump_insn_after (gen_jump (target_label), insn);
743 JUMP_LABEL (src->end) = target_label;
744 LABEL_NUSES (target_label)++;
746 fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n",
747 INSN_UID (insn), INSN_UID (src->end));
750 delete_insn_chain (kill_from, insn);
752 /* Recognize a tablejump that we are converting to a
753 simple jump and remove its associated CODE_LABEL
754 and ADDR_VEC or ADDR_DIFF_VEC. */
755 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
756 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
757 && GET_CODE (tmp) == JUMP_INSN
758 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
759 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
761 delete_insn_chain (JUMP_LABEL (insn), tmp);
764 barrier = next_nonnote_insn (src->end);
765 if (!barrier || GET_CODE (barrier) != BARRIER)
766 emit_barrier_after (src->end);
769 /* Keep only one edge out and set proper flags. */
770 while (src->succ->succ_next)
771 remove_edge (src->succ);
774 e->flags = EDGE_FALLTHRU;
778 e->probability = REG_BR_PROB_BASE;
779 e->count = src->count;
781 /* We don't want a block to end on a line-number note since that has
782 the potential of changing the code between -g and not -g. */
783 while (GET_CODE (e->src->end) == NOTE
784 && NOTE_LINE_NUMBER (e->src->end) >= 0)
785 delete_insn (e->src->end);
787 if (e->dest != target)
788 redirect_edge_succ (e, target);
793 /* Return last loop_beg note appearing after INSN, before start of next
794 basic block. Return INSN if there are no such notes.
796 When emitting jump to redirect an fallthru edge, it should always appear
797 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
798 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
802 last_loop_beg_note (insn)
807 for (insn = NEXT_INSN (insn); insn && GET_CODE (insn) == NOTE
808 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
809 insn = NEXT_INSN (insn))
810 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
816 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
817 expense of adding new instructions or reordering basic blocks.
819 Function can be also called with edge destination equivalent to the TARGET.
820 Then it should try the simplifications and do nothing if none is possible.
822 Return true if transformation succeeded. We still return false in case E
823 already destinated TARGET and we didn't managed to simplify instruction
827 redirect_edge_and_branch (e, target)
832 rtx old_label = e->dest->head;
833 basic_block src = e->src;
836 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
839 if (try_redirect_by_replacing_jump (e, target))
842 /* Do this fast path late, as we want above code to simplify for cases
843 where called on single edge leaving basic block containing nontrivial
845 else if (e->dest == target)
848 /* We can only redirect non-fallthru edges of jump insn. */
849 if (e->flags & EDGE_FALLTHRU)
851 else if (GET_CODE (insn) != JUMP_INSN)
854 /* Recognize a tablejump and adjust all matching cases. */
855 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
856 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
857 && GET_CODE (tmp) == JUMP_INSN
858 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
859 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
863 rtx new_label = block_label (target);
865 if (target == EXIT_BLOCK_PTR)
867 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
868 vec = XVEC (PATTERN (tmp), 0);
870 vec = XVEC (PATTERN (tmp), 1);
872 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
873 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
875 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
876 --LABEL_NUSES (old_label);
877 ++LABEL_NUSES (new_label);
880 /* Handle casesi dispatch insns */
881 if ((tmp = single_set (insn)) != NULL
882 && SET_DEST (tmp) == pc_rtx
883 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
884 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
885 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
887 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
889 --LABEL_NUSES (old_label);
890 ++LABEL_NUSES (new_label);
895 /* ?? We may play the games with moving the named labels from
896 one basic block to the other in case only one computed_jump is
898 if (computed_jump_p (insn)
899 /* A return instruction can't be redirected. */
900 || returnjump_p (insn))
903 /* If the insn doesn't go where we think, we're confused. */
904 if (JUMP_LABEL (insn) != old_label)
907 /* If the substitution doesn't succeed, die. This can happen
908 if the back end emitted unrecognizable instructions or if
909 target is exit block on some arches. */
910 if (!redirect_jump (insn, block_label (target), 0))
912 if (target == EXIT_BLOCK_PTR)
919 fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n",
920 e->src->index, e->dest->index, target->index);
922 if (e->dest != target)
923 redirect_edge_succ_nodup (e, target);
928 /* Like force_nonfallthru below, but additionally performs redirection
929 Used by redirect_edge_and_branch_force. */
932 force_nonfallthru_and_redirect (e, target)
936 basic_block jump_block, new_bb = NULL;
940 if (e->flags & EDGE_ABNORMAL)
942 else if (!(e->flags & EDGE_FALLTHRU))
944 else if (e->src == ENTRY_BLOCK_PTR)
946 /* We can't redirect the entry block. Create an empty block at the
947 start of the function which we use to add the new jump. */
949 basic_block bb = create_basic_block (e->dest->head, NULL, ENTRY_BLOCK_PTR);
951 /* Change the existing edge's source to be the new block, and add
952 a new edge from the entry block to the new block. */
954 for (pe1 = &ENTRY_BLOCK_PTR->succ; *pe1; pe1 = &(*pe1)->succ_next)
962 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
965 if (e->src->succ->succ_next)
967 /* Create the new structures. */
969 /* Position the new block correctly relative to loop notes. */
970 note = last_loop_beg_note (e->src->end);
971 note = NEXT_INSN (note);
973 /* ... and ADDR_VECs. */
975 && GET_CODE (note) == CODE_LABEL
977 && GET_CODE (NEXT_INSN (note)) == JUMP_INSN
978 && (GET_CODE (PATTERN (NEXT_INSN (note))) == ADDR_DIFF_VEC
979 || GET_CODE (PATTERN (NEXT_INSN (note))) == ADDR_VEC))
980 note = NEXT_INSN (NEXT_INSN (note));
982 jump_block = create_basic_block (note, NULL, e->src);
983 jump_block->count = e->count;
984 jump_block->frequency = EDGE_FREQUENCY (e);
985 jump_block->loop_depth = target->loop_depth;
987 if (target->global_live_at_start)
989 jump_block->global_live_at_start
990 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
991 jump_block->global_live_at_end
992 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
993 COPY_REG_SET (jump_block->global_live_at_start,
994 target->global_live_at_start);
995 COPY_REG_SET (jump_block->global_live_at_end,
996 target->global_live_at_start);
1000 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1001 new_edge->probability = e->probability;
1002 new_edge->count = e->count;
1004 /* Redirect old edge. */
1005 redirect_edge_pred (e, jump_block);
1006 e->probability = REG_BR_PROB_BASE;
1008 new_bb = jump_block;
1011 jump_block = e->src;
1013 e->flags &= ~EDGE_FALLTHRU;
1014 if (target == EXIT_BLOCK_PTR)
1017 emit_jump_insn_after (gen_return (), jump_block->end);
1023 rtx label = block_label (target);
1024 emit_jump_insn_after (gen_jump (label), jump_block->end);
1025 JUMP_LABEL (jump_block->end) = label;
1026 LABEL_NUSES (label)++;
1029 emit_barrier_after (jump_block->end);
1030 redirect_edge_succ_nodup (e, target);
1035 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1036 (and possibly create new basic block) to make edge non-fallthru.
1037 Return newly created BB or NULL if none. */
1040 force_nonfallthru (e)
1043 return force_nonfallthru_and_redirect (e, e->dest);
1046 /* Redirect edge even at the expense of creating new jump insn or
1047 basic block. Return new basic block if created, NULL otherwise.
1048 Abort if conversion is impossible. */
1051 redirect_edge_and_branch_force (e, target)
1055 if (redirect_edge_and_branch (e, target)
1056 || e->dest == target)
1059 /* In case the edge redirection failed, try to force it to be non-fallthru
1060 and redirect newly created simplejump. */
1061 return force_nonfallthru_and_redirect (e, target);
1064 /* The given edge should potentially be a fallthru edge. If that is in
1065 fact true, delete the jump and barriers that are in the way. */
1068 tidy_fallthru_edge (e, b, c)
1074 /* ??? In a late-running flow pass, other folks may have deleted basic
1075 blocks by nopping out blocks, leaving multiple BARRIERs between here
1076 and the target label. They ought to be chastized and fixed.
1078 We can also wind up with a sequence of undeletable labels between
1079 one block and the next.
1081 So search through a sequence of barriers, labels, and notes for
1082 the head of block C and assert that we really do fall through. */
1084 for (q = NEXT_INSN (b->end); q != c->head; q = NEXT_INSN (q))
1088 /* Remove what will soon cease being the jump insn from the source block.
1089 If block B consisted only of this single jump, turn it into a deleted
1092 if (GET_CODE (q) == JUMP_INSN
1094 && (any_uncondjump_p (q)
1095 || (b->succ == e && e->succ_next == NULL)))
1098 /* If this was a conditional jump, we need to also delete
1099 the insn that set cc0. */
1100 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1106 /* We don't want a block to end on a line-number note since that has
1107 the potential of changing the code between -g and not -g. */
1108 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
1112 /* Selectively unlink the sequence. */
1113 if (q != PREV_INSN (c->head))
1114 delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
1116 e->flags |= EDGE_FALLTHRU;
1119 /* Fix up edges that now fall through, or rather should now fall through
1120 but previously required a jump around now deleted blocks. Simplify
1121 the search by only examining blocks numerically adjacent, since this
1122 is how find_basic_blocks created them. */
1125 tidy_fallthru_edges ()
1129 if (ENTRY_BLOCK_PTR->next_bb == EXIT_BLOCK_PTR)
1132 FOR_BB_BETWEEN (b, ENTRY_BLOCK_PTR->next_bb, EXIT_BLOCK_PTR->prev_bb, next_bb)
1138 /* We care about simple conditional or unconditional jumps with
1141 If we had a conditional branch to the next instruction when
1142 find_basic_blocks was called, then there will only be one
1143 out edge for the block which ended with the conditional
1144 branch (since we do not create duplicate edges).
1146 Furthermore, the edge will be marked as a fallthru because we
1147 merge the flags for the duplicate edges. So we do not want to
1148 check that the edge is not a FALLTHRU edge. */
1150 if ((s = b->succ) != NULL
1151 && ! (s->flags & EDGE_COMPLEX)
1152 && s->succ_next == NULL
1154 /* If the jump insn has side effects, we can't tidy the edge. */
1155 && (GET_CODE (b->end) != JUMP_INSN
1156 || onlyjump_p (b->end)))
1157 tidy_fallthru_edge (s, b, c);
1161 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1162 is back edge of syntactic loop. */
1165 back_edge_of_syntactic_loop_p (bb1, bb2)
1166 basic_block bb1, bb2;
1175 /* ??? Could we guarantee that bb indices are monotone, so that we could
1176 just compare them? */
1177 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1183 for (insn = bb1->end; insn != bb2->head && count >= 0;
1184 insn = NEXT_INSN (insn))
1185 if (GET_CODE (insn) == NOTE)
1187 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1189 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1196 /* Split a (typically critical) edge. Return the new block.
1197 Abort on abnormal edges.
1199 ??? The code generally expects to be called on critical edges.
1200 The case of a block ending in an unconditional jump to a
1201 block with multiple predecessors is not handled optimally. */
1204 split_edge (edge_in)
1211 /* Abnormal edges cannot be split. */
1212 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1215 /* We are going to place the new block in front of edge destination.
1216 Avoid existence of fallthru predecessors. */
1217 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1221 for (e = edge_in->dest->pred; e; e = e->pred_next)
1222 if (e->flags & EDGE_FALLTHRU)
1226 force_nonfallthru (e);
1229 /* Create the basic block note.
1231 Where we place the note can have a noticeable impact on the generated
1232 code. Consider this cfg:
1242 If we need to insert an insn on the edge from block 0 to block 1,
1243 we want to ensure the instructions we insert are outside of any
1244 loop notes that physically sit between block 0 and block 1. Otherwise
1245 we confuse the loop optimizer into thinking the loop is a phony. */
1247 if (edge_in->dest != EXIT_BLOCK_PTR
1248 && PREV_INSN (edge_in->dest->head)
1249 && GET_CODE (PREV_INSN (edge_in->dest->head)) == NOTE
1250 && (NOTE_LINE_NUMBER (PREV_INSN (edge_in->dest->head))
1251 == NOTE_INSN_LOOP_BEG)
1252 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1253 before = PREV_INSN (edge_in->dest->head);
1254 else if (edge_in->dest != EXIT_BLOCK_PTR)
1255 before = edge_in->dest->head;
1259 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1260 bb->count = edge_in->count;
1261 bb->frequency = EDGE_FREQUENCY (edge_in);
1263 /* ??? This info is likely going to be out of date very soon. */
1264 if (edge_in->dest->global_live_at_start)
1266 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1267 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1268 COPY_REG_SET (bb->global_live_at_start,
1269 edge_in->dest->global_live_at_start);
1270 COPY_REG_SET (bb->global_live_at_end,
1271 edge_in->dest->global_live_at_start);
1274 edge_out = make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1276 /* For non-fallthry edges, we must adjust the predecessor's
1277 jump instruction to target our new block. */
1278 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1280 if (!redirect_edge_and_branch (edge_in, bb))
1284 redirect_edge_succ (edge_in, bb);
1289 /* Queue instructions for insertion on an edge between two basic blocks.
1290 The new instructions and basic blocks (if any) will not appear in the
1291 CFG until commit_edge_insertions is called. */
1294 insert_insn_on_edge (pattern, e)
1298 /* We cannot insert instructions on an abnormal critical edge.
1299 It will be easier to find the culprit if we die now. */
1300 if ((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))
1303 if (e->insns == NULL_RTX)
1306 push_to_sequence (e->insns);
1308 emit_insn (pattern);
1310 e->insns = get_insns ();
1314 /* Update the CFG for the instructions queued on edge E. */
1317 commit_one_edge_insertion (e, watch_calls)
1321 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1322 basic_block bb = NULL;
1324 /* Pull the insns off the edge now since the edge might go away. */
1326 e->insns = NULL_RTX;
1328 /* Special case -- avoid inserting code between call and storing
1329 its return value. */
1330 if (watch_calls && (e->flags & EDGE_FALLTHRU) && !e->dest->pred->pred_next
1331 && e->src != ENTRY_BLOCK_PTR
1332 && GET_CODE (e->src->end) == CALL_INSN)
1334 rtx next = next_nonnote_insn (e->src->end);
1336 after = e->dest->head;
1337 /* The first insn after the call may be a stack pop, skip it. */
1339 && keep_with_call_p (next))
1342 next = next_nonnote_insn (next);
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 (e->dest->pred->pred_next == NULL && 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. */
1357 if (GET_CODE (tmp) == CODE_LABEL)
1358 tmp = NEXT_INSN (tmp);
1359 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1360 tmp = NEXT_INSN (tmp);
1361 if (tmp == bb->head)
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 && e->src->succ->succ_next == NULL
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 (GET_CODE (bb->end) == JUMP_INSN)
1384 for (before = bb->end;
1385 GET_CODE (PREV_INSN (before)) == NOTE
1386 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1387 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1391 /* We'd better be fallthru, or we've lost track of what's what. */
1392 if ((e->flags & EDGE_FALLTHRU) == 0)
1398 /* Otherwise we must split the edge. */
1401 bb = split_edge (e);
1406 /* Now that we've found the spot, do the insertion. */
1410 emit_insn_before (insns, before);
1411 last = prev_nonnote_insn (before);
1414 last = emit_insn_after (insns, after);
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
1424 if (e->dest != EXIT_BLOCK_PTR
1425 || e->succ_next != NULL || (e->flags & EDGE_FALLTHRU) == 0)
1428 e->flags &= ~EDGE_FALLTHRU;
1429 emit_barrier_after (last);
1432 delete_insn (before);
1434 else if (GET_CODE (last) == JUMP_INSN)
1437 find_sub_basic_blocks (bb);
1440 /* Update the CFG for all queued instructions. */
1443 commit_edge_insertions ()
1447 #ifdef ENABLE_CHECKING
1448 verify_flow_info ();
1451 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1455 for (e = bb->succ; e; e = next)
1457 next = e->succ_next;
1459 commit_one_edge_insertion (e, false);
1464 /* Update the CFG for all queued instructions, taking special care of inserting
1465 code on edges between call and storing its return value. */
1468 commit_edge_insertions_watch_calls ()
1472 #ifdef ENABLE_CHECKING
1473 verify_flow_info ();
1476 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1480 for (e = bb->succ; e; e = next)
1482 next = e->succ_next;
1484 commit_one_edge_insertion (e, true);
1489 /* Print out one basic block with live information at start and end. */
1500 fprintf (outf, ";; Basic block %d, loop depth %d, count ",
1501 bb->index, bb->loop_depth);
1502 fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
1505 fputs (";; Predecessors: ", outf);
1506 for (e = bb->pred; e; e = e->pred_next)
1507 dump_edge_info (outf, e, 0);
1510 fputs (";; Registers live at start:", outf);
1511 dump_regset (bb->global_live_at_start, outf);
1514 for (insn = bb->head, last = NEXT_INSN (bb->end); insn != last;
1515 insn = NEXT_INSN (insn))
1516 print_rtl_single (outf, insn);
1518 fputs (";; Registers live at end:", outf);
1519 dump_regset (bb->global_live_at_end, outf);
1522 fputs (";; Successors: ", outf);
1523 for (e = bb->succ; e; e = e->succ_next)
1524 dump_edge_info (outf, e, 1);
1532 dump_bb (bb, stderr);
1539 dump_bb (BASIC_BLOCK (n), stderr);
1542 /* Like print_rtl, but also print out live information for the start of each
1546 print_rtl_with_bb (outf, rtx_first)
1553 fprintf (outf, "(nil)\n");
1556 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1557 int max_uid = get_max_uid ();
1559 = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
1561 = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
1562 enum bb_state *in_bb_p
1563 = (enum bb_state *) xcalloc (max_uid, sizeof (enum bb_state));
1567 FOR_EACH_BB_REVERSE (bb)
1571 start[INSN_UID (bb->head)] = bb;
1572 end[INSN_UID (bb->end)] = bb;
1573 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
1575 enum bb_state state = IN_MULTIPLE_BB;
1577 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1579 in_bb_p[INSN_UID (x)] = state;
1586 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1590 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1592 fprintf (outf, ";; Start of basic block %d, registers live:",
1594 dump_regset (bb->global_live_at_start, outf);
1598 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1599 && GET_CODE (tmp_rtx) != NOTE
1600 && GET_CODE (tmp_rtx) != BARRIER)
1601 fprintf (outf, ";; Insn is not within a basic block\n");
1602 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1603 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1605 did_output = print_rtl_single (outf, tmp_rtx);
1607 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1609 fprintf (outf, ";; End of basic block %d, registers live:\n",
1611 dump_regset (bb->global_live_at_end, outf);
1624 if (current_function_epilogue_delay_list != 0)
1626 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1627 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1628 tmp_rtx = XEXP (tmp_rtx, 1))
1629 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1634 update_br_prob_note (bb)
1638 if (GET_CODE (bb->end) != JUMP_INSN)
1640 note = find_reg_note (bb->end, REG_BR_PROB, NULL_RTX);
1641 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1643 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1646 /* Verify the CFG consistency. This function check some CFG invariants and
1647 aborts when something is wrong. Hope that this function will help to
1648 convert many optimization passes to preserve CFG consistent.
1650 Currently it does following checks:
1652 - test head/end pointers
1653 - overlapping of basic blocks
1654 - edge list correctness
1655 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1656 - tails of basic blocks (ensure that boundary is necessary)
1657 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1658 and NOTE_INSN_BASIC_BLOCK
1659 - check that all insns are in the basic blocks
1660 (except the switch handling code, barriers and notes)
1661 - check that all returns are followed by barriers
1663 In future it can be extended check a lot of other stuff as well
1664 (reachability of basic blocks, life information, etc. etc.). */
1669 const int max_uid = get_max_uid ();
1670 const rtx rtx_first = get_insns ();
1671 rtx last_head = get_last_insn ();
1672 basic_block *bb_info, *last_visited;
1673 size_t *edge_checksum;
1675 int num_bb_notes, err = 0;
1676 basic_block bb, last_bb_seen;
1678 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
1679 last_visited = (basic_block *) xcalloc (last_basic_block + 2,
1680 sizeof (basic_block));
1681 edge_checksum = (size_t *) xcalloc (last_basic_block + 2, sizeof (size_t));
1683 /* Check bb chain & numbers. */
1684 last_bb_seen = ENTRY_BLOCK_PTR;
1685 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR->next_bb, NULL, next_bb)
1687 if (bb != EXIT_BLOCK_PTR
1688 && bb != BASIC_BLOCK (bb->index))
1690 error ("bb %d on wrong place", bb->index);
1694 if (bb->prev_bb != last_bb_seen)
1696 error ("prev_bb of %d should be %d, not %d",
1697 bb->index, last_bb_seen->index, bb->prev_bb->index);
1704 FOR_EACH_BB_REVERSE (bb)
1706 rtx head = bb->head;
1709 /* Verify the end of the basic block is in the INSN chain. */
1710 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1716 error ("end insn %d for block %d not found in the insn stream",
1717 INSN_UID (end), bb->index);
1721 /* Work backwards from the end to the head of the basic block
1722 to verify the head is in the RTL chain. */
1723 for (; x != NULL_RTX; x = PREV_INSN (x))
1725 /* While walking over the insn chain, verify insns appear
1726 in only one basic block and initialize the BB_INFO array
1727 used by other passes. */
1728 if (bb_info[INSN_UID (x)] != NULL)
1730 error ("insn %d is in multiple basic blocks (%d and %d)",
1731 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1735 bb_info[INSN_UID (x)] = bb;
1742 error ("head insn %d for block %d not found in the insn stream",
1743 INSN_UID (head), bb->index);
1750 /* Now check the basic blocks (boundaries etc.) */
1751 FOR_EACH_BB_REVERSE (bb)
1753 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1757 if (INSN_P (bb->end)
1758 && (note = find_reg_note (bb->end, REG_BR_PROB, NULL_RTX))
1759 && bb->succ && bb->succ->succ_next
1760 && any_condjump_p (bb->end))
1762 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability)
1764 error ("verify_flow_info: REG_BR_PROB does not match cfg %i %i",
1765 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1771 error ("verify_flow_info: Wrong count of block %i %i",
1772 bb->index, (int)bb->count);
1775 if (bb->frequency < 0)
1777 error ("verify_flow_info: Wrong frequency of block %i %i",
1778 bb->index, bb->frequency);
1781 for (e = bb->succ; e; e = e->succ_next)
1783 if (last_visited [e->dest->index + 2] == bb)
1785 error ("verify_flow_info: Duplicate edge %i->%i",
1786 e->src->index, e->dest->index);
1789 if (e->probability < 0 || e->probability > REG_BR_PROB_BASE)
1791 error ("verify_flow_info: Wrong probability of edge %i->%i %i",
1792 e->src->index, e->dest->index, e->probability);
1797 error ("verify_flow_info: Wrong count of edge %i->%i %i",
1798 e->src->index, e->dest->index, (int)e->count);
1802 last_visited [e->dest->index + 2] = bb;
1804 if (e->flags & EDGE_FALLTHRU)
1807 if ((e->flags & ~EDGE_DFS_BACK) == 0)
1810 if (e->flags & EDGE_ABNORMAL_CALL)
1813 if (e->flags & EDGE_EH)
1815 else if (e->flags & EDGE_ABNORMAL)
1818 if ((e->flags & EDGE_FALLTHRU)
1819 && e->src != ENTRY_BLOCK_PTR
1820 && e->dest != EXIT_BLOCK_PTR)
1824 if (e->src->next_bb != e->dest)
1827 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
1828 e->src->index, e->dest->index);
1832 for (insn = NEXT_INSN (e->src->end); insn != e->dest->head;
1833 insn = NEXT_INSN (insn))
1834 if (GET_CODE (insn) == BARRIER
1835 #ifndef CASE_DROPS_THROUGH
1838 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
1842 error ("verify_flow_info: Incorrect fallthru %i->%i",
1843 e->src->index, e->dest->index);
1844 fatal_insn ("wrong insn in the fallthru edge", insn);
1851 error ("verify_flow_info: Basic block %d succ edge is corrupted",
1853 fprintf (stderr, "Predecessor: ");
1854 dump_edge_info (stderr, e, 0);
1855 fprintf (stderr, "\nSuccessor: ");
1856 dump_edge_info (stderr, e, 1);
1857 fprintf (stderr, "\n");
1861 edge_checksum[e->dest->index + 2] += (size_t) e;
1864 if (n_eh && GET_CODE (PATTERN (bb->end)) != RESX
1865 && !find_reg_note (bb->end, REG_EH_REGION, NULL_RTX))
1867 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
1871 && (GET_CODE (bb->end) != JUMP_INSN
1872 || (n_branch > 1 && (any_uncondjump_p (bb->end)
1873 || any_condjump_p (bb->end)))))
1875 error ("Too many outgoing branch edges from bb %i", bb->index);
1878 if (n_fallthru && any_uncondjump_p (bb->end))
1880 error ("Fallthru edge after unconditional jump %i", bb->index);
1883 if (n_branch != 1 && any_uncondjump_p (bb->end))
1885 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
1888 if (n_branch != 1 && any_condjump_p (bb->end)
1889 && JUMP_LABEL (bb->end) != bb->next_bb->head)
1891 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
1894 if (n_call && GET_CODE (bb->end) != CALL_INSN)
1896 error ("Call edges for non-call insn in bb %i", bb->index);
1900 && (GET_CODE (bb->end) != CALL_INSN && n_call != n_abnormal)
1901 && (GET_CODE (bb->end) != JUMP_INSN
1902 || any_condjump_p (bb->end)
1903 || any_uncondjump_p (bb->end)))
1905 error ("Abnormal edges for no purpose in bb %i", bb->index);
1913 /* Ensure existence of barrier in BB with no fallthru edges. */
1914 for (insn = bb->end; !insn || GET_CODE (insn) != BARRIER;
1915 insn = NEXT_INSN (insn))
1917 || (GET_CODE (insn) == NOTE
1918 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
1920 error ("missing barrier after block %i", bb->index);
1926 for (e = bb->pred; e; e = e->pred_next)
1930 error ("basic block %d pred edge is corrupted", bb->index);
1931 fputs ("Predecessor: ", stderr);
1932 dump_edge_info (stderr, e, 0);
1933 fputs ("\nSuccessor: ", stderr);
1934 dump_edge_info (stderr, e, 1);
1935 fputc ('\n', stderr);
1938 edge_checksum[e->dest->index + 2] -= (size_t) e;
1941 for (x = bb->head; x != NEXT_INSN (bb->end); x = NEXT_INSN (x))
1942 if (BLOCK_FOR_INSN (x) != bb)
1945 if (! BLOCK_FOR_INSN (x))
1947 ("insn %d inside basic block %d but block_for_insn is NULL",
1948 INSN_UID (x), bb->index);
1951 ("insn %d inside basic block %d but block_for_insn is %i",
1952 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1957 /* OK pointers are correct. Now check the header of basic
1958 block. It ought to contain optional CODE_LABEL followed
1959 by NOTE_BASIC_BLOCK. */
1961 if (GET_CODE (x) == CODE_LABEL)
1965 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1973 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1975 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1981 /* Do checks for empty blocks her. e */
1984 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1986 if (NOTE_INSN_BASIC_BLOCK_P (x))
1988 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1989 INSN_UID (x), bb->index);
1996 if (GET_CODE (x) == JUMP_INSN
1997 || GET_CODE (x) == CODE_LABEL
1998 || GET_CODE (x) == BARRIER)
2000 error ("in basic block %d:", bb->index);
2001 fatal_insn ("flow control insn inside a basic block", x);
2006 /* Complete edge checksumming for ENTRY and EXIT. */
2010 for (e = ENTRY_BLOCK_PTR->succ; e ; e = e->succ_next)
2011 edge_checksum[e->dest->index + 2] += (size_t) e;
2013 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
2014 edge_checksum[e->dest->index + 2] -= (size_t) e;
2017 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, NULL, next_bb)
2018 if (edge_checksum[bb->index + 2])
2020 error ("basic block %i edge lists are corrupted", bb->index);
2025 last_bb_seen = ENTRY_BLOCK_PTR;
2027 for (x = rtx_first; x; x = NEXT_INSN (x))
2029 if (NOTE_INSN_BASIC_BLOCK_P (x))
2031 bb = NOTE_BASIC_BLOCK (x);
2034 if (bb != last_bb_seen->next_bb)
2035 internal_error ("basic blocks not numbered consecutively");
2040 if (!bb_info[INSN_UID (x)])
2042 switch (GET_CODE (x))
2049 /* An addr_vec is placed outside any block block. */
2051 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
2052 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2053 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2056 /* But in any case, non-deletable labels can appear anywhere. */
2060 fatal_insn ("insn outside basic block", x);
2065 && GET_CODE (x) == JUMP_INSN
2066 && returnjump_p (x) && ! condjump_p (x)
2067 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
2068 fatal_insn ("return not followed by barrier", x);
2071 if (num_bb_notes != n_basic_blocks)
2073 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2074 num_bb_notes, n_basic_blocks);
2077 internal_error ("verify_flow_info failed");
2081 free (last_visited);
2082 free (edge_checksum);
2085 /* Assume that the preceding pass has possibly eliminated jump instructions
2086 or converted the unconditional jumps. Eliminate the edges from CFG.
2087 Return true if any edges are eliminated. */
2090 purge_dead_edges (bb)
2094 rtx insn = bb->end, note;
2095 bool purged = false;
2097 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2098 if (GET_CODE (insn) == INSN
2099 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2103 if (! may_trap_p (PATTERN (insn))
2104 || ((eqnote = find_reg_equal_equiv_note (insn))
2105 && ! may_trap_p (XEXP (eqnote, 0))))
2106 remove_note (insn, note);
2109 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2110 for (e = bb->succ; e; e = next)
2112 next = e->succ_next;
2113 if (e->flags & EDGE_EH)
2115 if (can_throw_internal (bb->end))
2118 else if (e->flags & EDGE_ABNORMAL_CALL)
2120 if (GET_CODE (bb->end) == CALL_INSN
2121 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2122 || INTVAL (XEXP (note, 0)) >= 0))
2129 bb->flags |= BB_DIRTY;
2133 if (GET_CODE (insn) == JUMP_INSN)
2138 /* We do care only about conditional jumps and simplejumps. */
2139 if (!any_condjump_p (insn)
2140 && !returnjump_p (insn)
2141 && !simplejump_p (insn))
2144 /* Branch probability/prediction notes are defined only for
2145 condjumps. We've possibly turned condjump into simplejump. */
2146 if (simplejump_p (insn))
2148 note = find_reg_note (insn, REG_BR_PROB, NULL);
2150 remove_note (insn, note);
2151 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2152 remove_note (insn, note);
2155 for (e = bb->succ; e; e = next)
2157 next = e->succ_next;
2159 /* Avoid abnormal flags to leak from computed jumps turned
2160 into simplejumps. */
2162 e->flags &= ~EDGE_ABNORMAL;
2164 /* See if this edge is one we should keep. */
2165 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2166 /* A conditional jump can fall through into the next
2167 block, so we should keep the edge. */
2169 else if (e->dest != EXIT_BLOCK_PTR
2170 && e->dest->head == JUMP_LABEL (insn))
2171 /* If the destination block is the target of the jump,
2174 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2175 /* If the destination block is the exit block, and this
2176 instruction is a return, then keep the edge. */
2178 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2179 /* Keep the edges that correspond to exceptions thrown by
2180 this instruction. */
2183 /* We do not need this edge. */
2184 bb->flags |= BB_DIRTY;
2189 if (!bb->succ || !purged)
2193 fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
2198 /* Redistribute probabilities. */
2199 if (!bb->succ->succ_next)
2201 bb->succ->probability = REG_BR_PROB_BASE;
2202 bb->succ->count = bb->count;
2206 note = find_reg_note (insn, REG_BR_PROB, NULL);
2210 b = BRANCH_EDGE (bb);
2211 f = FALLTHRU_EDGE (bb);
2212 b->probability = INTVAL (XEXP (note, 0));
2213 f->probability = REG_BR_PROB_BASE - b->probability;
2214 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2215 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2221 /* If we don't see a jump insn, we don't know exactly why the block would
2222 have been broken at this point. Look for a simple, non-fallthru edge,
2223 as these are only created by conditional branches. If we find such an
2224 edge we know that there used to be a jump here and can then safely
2225 remove all non-fallthru edges. */
2226 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
2233 for (e = bb->succ; e; e = next)
2235 next = e->succ_next;
2236 if (!(e->flags & EDGE_FALLTHRU))
2238 bb->flags |= BB_DIRTY;
2244 if (!bb->succ || bb->succ->succ_next)
2247 bb->succ->probability = REG_BR_PROB_BASE;
2248 bb->succ->count = bb->count;
2251 fprintf (rtl_dump_file, "Purged non-fallthru edges from bb %i\n",
2256 /* Search all basic blocks for potentially dead edges and purge them. Return
2257 true if some edge has been eliminated. */
2260 purge_all_dead_edges (update_life_p)
2269 blocks = sbitmap_alloc (last_basic_block);
2270 sbitmap_zero (blocks);
2275 bool purged_here = purge_dead_edges (bb);
2277 purged |= purged_here;
2278 if (purged_here && update_life_p)
2279 SET_BIT (blocks, bb->index);
2282 if (update_life_p && purged)
2283 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2284 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2285 | PROP_KILL_DEAD_CODE);
2288 sbitmap_free (blocks);