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 basic block structure for every insn, indexed by uid. */
68 varray_type basic_block_for_insn;
70 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
71 /* ??? Should probably be using LABEL_NUSES instead. It would take a
72 bit of surgery to be able to use or co-opt the routines in jump. */
74 rtx tail_recursion_label_list;
76 static int can_delete_note_p PARAMS ((rtx));
77 static int can_delete_label_p PARAMS ((rtx));
78 static void commit_one_edge_insertion PARAMS ((edge, int));
79 static bool try_redirect_by_replacing_jump PARAMS ((edge, basic_block));
80 static rtx last_loop_beg_note PARAMS ((rtx));
81 static bool back_edge_of_syntactic_loop_p PARAMS ((basic_block, basic_block));
82 static basic_block force_nonfallthru_and_redirect PARAMS ((edge, basic_block));
84 /* Return true if NOTE is not one of the ones that must be kept paired,
85 so that we may simply delete it. */
88 can_delete_note_p (note)
91 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
92 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK);
95 /* True if a given label can be deleted. */
98 can_delete_label_p (label)
101 return (!LABEL_PRESERVE_P (label)
102 /* User declared labels must be preserved. */
103 && LABEL_NAME (label) == 0
104 && !in_expr_list_p (forced_labels, label)
105 && !in_expr_list_p (label_value_list, label));
108 /* Delete INSN by patching it out. Return the next insn. */
114 rtx next = NEXT_INSN (insn);
116 bool really_delete = true;
118 if (GET_CODE (insn) == CODE_LABEL)
120 /* Some labels can't be directly removed from the INSN chain, as they
121 might be references via variables, constant pool etc.
122 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
123 if (! can_delete_label_p (insn))
125 const char *name = LABEL_NAME (insn);
127 really_delete = false;
128 PUT_CODE (insn, NOTE);
129 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
130 NOTE_SOURCE_FILE (insn) = name;
133 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
138 /* If this insn has already been deleted, something is very wrong. */
139 if (INSN_DELETED_P (insn))
142 INSN_DELETED_P (insn) = 1;
145 /* If deleting a jump, decrement the use count of the label. Deleting
146 the label itself should happen in the normal course of block merging. */
147 if (GET_CODE (insn) == JUMP_INSN
149 && GET_CODE (JUMP_LABEL (insn)) == CODE_LABEL)
150 LABEL_NUSES (JUMP_LABEL (insn))--;
152 /* Also if deleting an insn that references a label. */
153 else if ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
154 && GET_CODE (XEXP (note, 0)) == CODE_LABEL)
155 LABEL_NUSES (XEXP (note, 0))--;
157 if (GET_CODE (insn) == JUMP_INSN
158 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
159 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
161 rtx pat = PATTERN (insn);
162 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
163 int len = XVECLEN (pat, diff_vec_p);
166 for (i = 0; i < len; i++)
168 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
170 /* When deleting code in bulk (e.g. removing many unreachable
171 blocks) we can delete a label that's a target of the vector
172 before deleting the vector itself. */
173 if (GET_CODE (label) != NOTE)
174 LABEL_NUSES (label)--;
181 /* Like delete_insn but also purge dead edges from BB. */
183 delete_insn_and_edges (insn)
189 if (basic_block_for_insn
191 && (unsigned int)INSN_UID (insn) < basic_block_for_insn->num_elements
192 && BLOCK_FOR_INSN (insn)
193 && BLOCK_FOR_INSN (insn)->end == insn)
195 x = delete_insn (insn);
197 purge_dead_edges (BLOCK_FOR_INSN (insn));
201 /* Unlink a chain of insns between START and FINISH, leaving notes
202 that must be paired. */
205 delete_insn_chain (start, finish)
210 /* Unchain the insns one by one. It would be quicker to delete all of these
211 with a single unchaining, rather than one at a time, but we need to keep
215 next = NEXT_INSN (start);
216 if (GET_CODE (start) == NOTE && !can_delete_note_p (start))
219 next = delete_insn (start);
227 /* Like delete_insn but also purge dead edges from BB. */
229 delete_insn_chain_and_edges (first, last)
234 if (basic_block_for_insn
236 && (unsigned int)INSN_UID (last) < basic_block_for_insn->num_elements
237 && BLOCK_FOR_INSN (last)
238 && BLOCK_FOR_INSN (last)->end == last)
240 delete_insn_chain (first, last);
242 purge_dead_edges (BLOCK_FOR_INSN (last));
245 /* Create a new basic block consisting of the instructions between HEAD and END
246 inclusive. This function is designed to allow fast BB construction - reuses
247 the note and basic block struct in BB_NOTE, if any and do not grow
248 BASIC_BLOCK chain and should be used directly only by CFG construction code.
249 END can be NULL in to create new empty basic block before HEAD. Both END
250 and HEAD can be NULL to create basic block at the end of INSN chain. */
253 create_basic_block_structure (index, head, end, bb_note)
255 rtx head, end, bb_note;
260 && ! RTX_INTEGRATED_P (bb_note)
261 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
264 /* If we found an existing note, thread it back onto the chain. */
268 if (GET_CODE (head) == CODE_LABEL)
272 after = PREV_INSN (head);
276 if (after != bb_note && NEXT_INSN (after) != bb_note)
277 reorder_insns (bb_note, bb_note, after);
281 /* Otherwise we must create a note and a basic block structure. */
287 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
288 else if (GET_CODE (head) == CODE_LABEL && end)
290 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
296 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
302 NOTE_BASIC_BLOCK (bb_note) = bb;
305 /* Always include the bb note in the block. */
306 if (NEXT_INSN (end) == bb_note)
313 BASIC_BLOCK (index) = bb;
314 if (basic_block_for_insn)
315 update_bb_for_insn (bb);
317 /* Tag the block so that we know it has been used when considering
318 other basic block notes. */
324 /* Create new basic block consisting of instructions in between HEAD and END
325 and place it to the BB chain at position INDEX. END can be NULL in to
326 create new empty basic block before HEAD. Both END and HEAD can be NULL to
327 create basic block at the end of INSN chain. */
330 create_basic_block (index, head, end)
337 /* Place the new block just after the block being split. */
338 VARRAY_GROW (basic_block_info, ++n_basic_blocks);
340 /* Some parts of the compiler expect blocks to be number in
341 sequential order so insert the new block immediately after the
342 block being split.. */
343 for (i = n_basic_blocks - 1; i > index; --i)
345 basic_block tmp = BASIC_BLOCK (i - 1);
347 BASIC_BLOCK (i) = tmp;
351 bb = create_basic_block_structure (index, head, end, NULL);
356 /* Delete the insns in a (non-live) block. We physically delete every
357 non-deleted-note insn, and update the flow graph appropriately.
359 Return nonzero if we deleted an exception handler. */
361 /* ??? Preserving all such notes strikes me as wrong. It would be nice
362 to post-process the stream to remove empty blocks, loops, ranges, etc. */
365 flow_delete_block_noexpunge (b)
368 int deleted_handler = 0;
371 /* If the head of this block is a CODE_LABEL, then it might be the
372 label for an exception handler which can't be reached.
374 We need to remove the label from the exception_handler_label list
375 and remove the associated NOTE_INSN_EH_REGION_BEG and
376 NOTE_INSN_EH_REGION_END notes. */
380 never_reached_warning (insn, b->end);
382 if (GET_CODE (insn) == CODE_LABEL)
383 maybe_remove_eh_handler (insn);
385 /* Include any jump table following the basic block. */
387 if (GET_CODE (end) == JUMP_INSN
388 && (tmp = JUMP_LABEL (end)) != NULL_RTX
389 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
390 && GET_CODE (tmp) == JUMP_INSN
391 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
392 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
395 /* Include any barrier that may follow the basic block. */
396 tmp = next_nonnote_insn (end);
397 if (tmp && GET_CODE (tmp) == BARRIER)
400 /* Selectively delete the entire chain. */
402 delete_insn_chain (insn, end);
404 /* Remove the edges into and out of this block. Note that there may
405 indeed be edges in, if we are removing an unreachable loop. */
406 while (b->pred != NULL)
407 remove_edge (b->pred);
408 while (b->succ != NULL)
409 remove_edge (b->succ);
414 return deleted_handler;
418 flow_delete_block (b)
421 int deleted_handler = flow_delete_block_noexpunge (b);
423 /* Remove the basic block from the array, and compact behind it. */
426 return deleted_handler;
429 /* Records the basic block struct in BB_FOR_INSN, for every instruction
430 indexed by INSN_UID. MAX is the size of the array. */
433 compute_bb_for_insn (max)
438 if (basic_block_for_insn)
439 VARRAY_FREE (basic_block_for_insn);
441 VARRAY_BB_INIT (basic_block_for_insn, max, "basic_block_for_insn");
443 for (i = 0; i < n_basic_blocks; ++i)
445 basic_block bb = BASIC_BLOCK (i);
449 for (insn = bb->head; ; insn = NEXT_INSN (insn))
451 if (INSN_UID (insn) < max)
452 VARRAY_BB (basic_block_for_insn, INSN_UID (insn)) = bb;
460 /* Release the basic_block_for_insn array. */
465 if (basic_block_for_insn)
466 VARRAY_FREE (basic_block_for_insn);
468 basic_block_for_insn = 0;
471 /* Update insns block within BB. */
474 update_bb_for_insn (bb)
479 if (! basic_block_for_insn)
482 for (insn = bb->head; ; insn = NEXT_INSN (insn))
484 set_block_for_insn (insn, bb);
490 /* Record INSN's block as BB. */
493 set_block_for_insn (insn, bb)
497 size_t uid = INSN_UID (insn);
499 if (uid >= basic_block_for_insn->num_elements)
501 /* Add one-eighth the size so we don't keep calling xrealloc. */
502 size_t new_size = uid + (uid + 7) / 8;
504 VARRAY_GROW (basic_block_for_insn, new_size);
507 VARRAY_BB (basic_block_for_insn, uid) = bb;
510 /* Split a block BB after insn INSN creating a new fallthru edge.
511 Return the new edge. Note that to keep other parts of the compiler happy,
512 this function renumbers all the basic blocks so that the new
513 one has a number one greater than the block split. */
516 split_block (bb, insn)
524 /* There is no point splitting the block after its end. */
528 /* Create the new basic block. */
529 new_bb = create_basic_block (bb->index + 1, NEXT_INSN (insn), bb->end);
530 new_bb->count = bb->count;
531 new_bb->frequency = bb->frequency;
532 new_bb->loop_depth = bb->loop_depth;
535 /* Redirect the outgoing edges. */
536 new_bb->succ = bb->succ;
538 for (e = new_bb->succ; e; e = e->succ_next)
541 new_edge = make_single_succ_edge (bb, new_bb, EDGE_FALLTHRU);
543 if (bb->global_live_at_start)
545 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
546 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
547 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
549 /* We now have to calculate which registers are live at the end
550 of the split basic block and at the start of the new basic
551 block. Start with those registers that are known to be live
552 at the end of the original basic block and get
553 propagate_block to determine which registers are live. */
554 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
555 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
556 COPY_REG_SET (bb->global_live_at_end,
557 new_bb->global_live_at_start);
558 #ifdef HAVE_conditional_execution
559 /* In the presence of conditional execution we are not able to update
560 liveness precisely. */
561 if (reload_completed)
563 bb->flags |= BB_DIRTY;
564 new_bb->flags |= BB_DIRTY;
572 /* Blocks A and B are to be merged into a single block A. The insns
573 are already contiguous, hence `nomove'. */
576 merge_blocks_nomove (a, b)
579 rtx b_head = b->head, b_end = b->end, a_end = a->end;
580 rtx del_first = NULL_RTX, del_last = NULL_RTX;
584 /* If there was a CODE_LABEL beginning B, delete it. */
585 if (GET_CODE (b_head) == CODE_LABEL)
587 /* Detect basic blocks with nothing but a label. This can happen
588 in particular at the end of a function. */
592 del_first = del_last = b_head;
593 b_head = NEXT_INSN (b_head);
596 /* Delete the basic block note and handle blocks containing just that
598 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
606 b_head = NEXT_INSN (b_head);
609 /* If there was a jump out of A, delete it. */
610 if (GET_CODE (a_end) == JUMP_INSN)
614 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
615 if (GET_CODE (prev) != NOTE
616 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
623 /* If this was a conditional jump, we need to also delete
624 the insn that set cc0. */
625 if (only_sets_cc0_p (prev))
629 prev = prev_nonnote_insn (prev);
636 a_end = PREV_INSN (del_first);
638 else if (GET_CODE (NEXT_INSN (a_end)) == BARRIER)
639 del_first = NEXT_INSN (a_end);
641 /* Normally there should only be one successor of A and that is B, but
642 partway though the merge of blocks for conditional_execution we'll
643 be merging a TEST block with THEN and ELSE successors. Free the
644 whole lot of them and hope the caller knows what they're doing. */
646 remove_edge (a->succ);
648 /* Adjust the edges out of B for the new owner. */
649 for (e = b->succ; e; e = e->succ_next)
652 a->flags |= b->flags;
654 /* B hasn't quite yet ceased to exist. Attempt to prevent mishap. */
655 b->pred = b->succ = NULL;
656 a->global_live_at_end = b->global_live_at_end;
660 /* Delete everything marked above as well as crap that might be
661 hanging out between the two blocks. */
662 delete_insn_chain (del_first, del_last);
664 /* Reassociate the insns of B with A. */
667 if (basic_block_for_insn)
671 for (x = a_end; x != b_end; x = NEXT_INSN (x))
672 set_block_for_insn (x, a);
674 set_block_for_insn (b_end, a);
683 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
690 if (block == EXIT_BLOCK_PTR)
693 if (GET_CODE (block->head) != CODE_LABEL)
695 block->head = emit_label_before (gen_label_rtx (), block->head);
696 if (basic_block_for_insn)
697 set_block_for_insn (block->head, block);
703 /* Attempt to perform edge redirection by replacing possibly complex jump
704 instruction by unconditional jump or removing jump completely. This can
705 apply only if all edges now point to the same block. The parameters and
706 return values are equivalent to redirect_edge_and_branch. */
709 try_redirect_by_replacing_jump (e, target)
713 basic_block src = e->src;
714 rtx insn = src->end, kill_from;
719 /* Verify that all targets will be TARGET. */
720 for (tmp = src->succ; tmp; tmp = tmp->succ_next)
721 if (tmp->dest != target && tmp != e)
724 if (tmp || !onlyjump_p (insn))
727 /* Avoid removing branch with side effects. */
728 set = single_set (insn);
729 if (!set || side_effects_p (set))
732 /* In case we zap a conditional jump, we'll need to kill
733 the cc0 setter too. */
736 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
737 kill_from = PREV_INSN (insn);
740 /* See if we can create the fallthru edge. */
741 if (can_fallthru (src, target))
744 fprintf (rtl_dump_file, "Removing jump %i.\n", INSN_UID (insn));
747 /* Selectively unlink whole insn chain. */
748 delete_insn_chain (kill_from, PREV_INSN (target->head));
751 /* If this already is simplejump, redirect it. */
752 else if (simplejump_p (insn))
754 if (e->dest == target)
757 fprintf (rtl_dump_file, "Redirecting jump %i from %i to %i.\n",
758 INSN_UID (insn), e->dest->index, target->index);
759 if (!redirect_jump (insn, block_label (target), 0))
761 if (target == EXIT_BLOCK_PTR)
767 /* Cannot do anything for target exit block. */
768 else if (target == EXIT_BLOCK_PTR)
771 /* Or replace possibly complicated jump insn by simple jump insn. */
774 rtx target_label = block_label (target);
777 emit_jump_insn_after (gen_jump (target_label), insn);
778 JUMP_LABEL (src->end) = target_label;
779 LABEL_NUSES (target_label)++;
781 fprintf (rtl_dump_file, "Replacing insn %i by jump %i\n",
782 INSN_UID (insn), INSN_UID (src->end));
785 delete_insn_chain (kill_from, insn);
787 /* Recognize a tablejump that we are converting to a
788 simple jump and remove its associated CODE_LABEL
789 and ADDR_VEC or ADDR_DIFF_VEC. */
790 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
791 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
792 && GET_CODE (tmp) == JUMP_INSN
793 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
794 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
796 delete_insn_chain (JUMP_LABEL (insn), tmp);
799 barrier = next_nonnote_insn (src->end);
800 if (!barrier || GET_CODE (barrier) != BARRIER)
801 emit_barrier_after (src->end);
804 /* Keep only one edge out and set proper flags. */
805 while (src->succ->succ_next)
806 remove_edge (src->succ);
809 e->flags = EDGE_FALLTHRU;
813 e->probability = REG_BR_PROB_BASE;
814 e->count = src->count;
816 /* We don't want a block to end on a line-number note since that has
817 the potential of changing the code between -g and not -g. */
818 while (GET_CODE (e->src->end) == NOTE
819 && NOTE_LINE_NUMBER (e->src->end) >= 0)
820 delete_insn (e->src->end);
822 if (e->dest != target)
823 redirect_edge_succ (e, target);
828 /* Return last loop_beg note appearing after INSN, before start of next
829 basic block. Return INSN if there are no such notes.
831 When emitting jump to redirect an fallthru edge, it should always appear
832 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
833 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
837 last_loop_beg_note (insn)
842 for (insn = NEXT_INSN (insn); insn && GET_CODE (insn) == NOTE
843 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
844 insn = NEXT_INSN (insn))
845 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
851 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
852 expense of adding new instructions or reordering basic blocks.
854 Function can be also called with edge destination equivalent to the TARGET.
855 Then it should try the simplifications and do nothing if none is possible.
857 Return true if transformation succeeded. We still return false in case E
858 already destinated TARGET and we didn't managed to simplify instruction
862 redirect_edge_and_branch (e, target)
867 rtx old_label = e->dest->head;
868 basic_block src = e->src;
871 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
874 if (try_redirect_by_replacing_jump (e, target))
877 /* Do this fast path late, as we want above code to simplify for cases
878 where called on single edge leaving basic block containing nontrivial
880 else if (e->dest == target)
883 /* We can only redirect non-fallthru edges of jump insn. */
884 if (e->flags & EDGE_FALLTHRU)
886 else if (GET_CODE (insn) != JUMP_INSN)
889 /* Recognize a tablejump and adjust all matching cases. */
890 if ((tmp = JUMP_LABEL (insn)) != NULL_RTX
891 && (tmp = NEXT_INSN (tmp)) != NULL_RTX
892 && GET_CODE (tmp) == JUMP_INSN
893 && (GET_CODE (PATTERN (tmp)) == ADDR_VEC
894 || GET_CODE (PATTERN (tmp)) == ADDR_DIFF_VEC))
898 rtx new_label = block_label (target);
900 if (target == EXIT_BLOCK_PTR)
902 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
903 vec = XVEC (PATTERN (tmp), 0);
905 vec = XVEC (PATTERN (tmp), 1);
907 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
908 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
910 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
911 --LABEL_NUSES (old_label);
912 ++LABEL_NUSES (new_label);
915 /* Handle casesi dispatch insns */
916 if ((tmp = single_set (insn)) != NULL
917 && SET_DEST (tmp) == pc_rtx
918 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
919 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
920 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
922 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
924 --LABEL_NUSES (old_label);
925 ++LABEL_NUSES (new_label);
930 /* ?? We may play the games with moving the named labels from
931 one basic block to the other in case only one computed_jump is
933 if (computed_jump_p (insn)
934 /* A return instruction can't be redirected. */
935 || returnjump_p (insn))
938 /* If the insn doesn't go where we think, we're confused. */
939 if (JUMP_LABEL (insn) != old_label)
942 /* If the substitution doesn't succeed, die. This can happen
943 if the back end emitted unrecognizable instructions or if
944 target is exit block on some arches. */
945 if (!redirect_jump (insn, block_label (target), 0))
947 if (target == EXIT_BLOCK_PTR)
954 fprintf (rtl_dump_file, "Edge %i->%i redirected to %i\n",
955 e->src->index, e->dest->index, target->index);
957 if (e->dest != target)
958 redirect_edge_succ_nodup (e, target);
963 /* Like force_nonfallthru below, but additionally performs redirection
964 Used by redirect_edge_and_branch_force. */
967 force_nonfallthru_and_redirect (e, target)
971 basic_block jump_block, new_bb = NULL;
975 if (e->flags & EDGE_ABNORMAL)
977 else if (!(e->flags & EDGE_FALLTHRU))
979 else if (e->src == ENTRY_BLOCK_PTR)
981 /* We can't redirect the entry block. Create an empty block at the
982 start of the function which we use to add the new jump. */
984 basic_block bb = create_basic_block (0, e->dest->head, NULL);
986 /* Change the existing edge's source to be the new block, and add
987 a new edge from the entry block to the new block. */
989 for (pe1 = &ENTRY_BLOCK_PTR->succ; *pe1; pe1 = &(*pe1)->succ_next)
997 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1000 if (e->src->succ->succ_next)
1002 /* Create the new structures. */
1003 note = last_loop_beg_note (e->src->end);
1005 = create_basic_block (e->src->index + 1, NEXT_INSN (note), NULL);
1006 jump_block->count = e->count;
1007 jump_block->frequency = EDGE_FREQUENCY (e);
1008 jump_block->loop_depth = target->loop_depth;
1010 if (target->global_live_at_start)
1012 jump_block->global_live_at_start
1013 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1014 jump_block->global_live_at_end
1015 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1016 COPY_REG_SET (jump_block->global_live_at_start,
1017 target->global_live_at_start);
1018 COPY_REG_SET (jump_block->global_live_at_end,
1019 target->global_live_at_start);
1023 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1024 new_edge->probability = e->probability;
1025 new_edge->count = e->count;
1027 /* Redirect old edge. */
1028 redirect_edge_pred (e, jump_block);
1029 e->probability = REG_BR_PROB_BASE;
1031 new_bb = jump_block;
1034 jump_block = e->src;
1036 e->flags &= ~EDGE_FALLTHRU;
1037 if (target == EXIT_BLOCK_PTR)
1040 emit_jump_insn_after (gen_return (), jump_block->end);
1046 rtx label = block_label (target);
1047 emit_jump_insn_after (gen_jump (label), jump_block->end);
1048 JUMP_LABEL (jump_block->end) = label;
1049 LABEL_NUSES (label)++;
1052 emit_barrier_after (jump_block->end);
1053 redirect_edge_succ_nodup (e, target);
1058 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1059 (and possibly create new basic block) to make edge non-fallthru.
1060 Return newly created BB or NULL if none. */
1063 force_nonfallthru (e)
1066 return force_nonfallthru_and_redirect (e, e->dest);
1069 /* Redirect edge even at the expense of creating new jump insn or
1070 basic block. Return new basic block if created, NULL otherwise.
1071 Abort if conversion is impossible. */
1074 redirect_edge_and_branch_force (e, target)
1078 if (redirect_edge_and_branch (e, target)
1079 || e->dest == target)
1082 /* In case the edge redirection failed, try to force it to be non-fallthru
1083 and redirect newly created simplejump. */
1084 return force_nonfallthru_and_redirect (e, target);
1087 /* The given edge should potentially be a fallthru edge. If that is in
1088 fact true, delete the jump and barriers that are in the way. */
1091 tidy_fallthru_edge (e, b, c)
1097 /* ??? In a late-running flow pass, other folks may have deleted basic
1098 blocks by nopping out blocks, leaving multiple BARRIERs between here
1099 and the target label. They ought to be chastized and fixed.
1101 We can also wind up with a sequence of undeletable labels between
1102 one block and the next.
1104 So search through a sequence of barriers, labels, and notes for
1105 the head of block C and assert that we really do fall through. */
1107 for (q = NEXT_INSN (b->end); q != c->head; q = NEXT_INSN (q))
1111 /* Remove what will soon cease being the jump insn from the source block.
1112 If block B consisted only of this single jump, turn it into a deleted
1115 if (GET_CODE (q) == JUMP_INSN
1117 && (any_uncondjump_p (q)
1118 || (b->succ == e && e->succ_next == NULL)))
1121 /* If this was a conditional jump, we need to also delete
1122 the insn that set cc0. */
1123 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1129 /* We don't want a block to end on a line-number note since that has
1130 the potential of changing the code between -g and not -g. */
1131 while (GET_CODE (q) == NOTE && NOTE_LINE_NUMBER (q) >= 0)
1135 /* Selectively unlink the sequence. */
1136 if (q != PREV_INSN (c->head))
1137 delete_insn_chain (NEXT_INSN (q), PREV_INSN (c->head));
1139 e->flags |= EDGE_FALLTHRU;
1142 /* Fix up edges that now fall through, or rather should now fall through
1143 but previously required a jump around now deleted blocks. Simplify
1144 the search by only examining blocks numerically adjacent, since this
1145 is how find_basic_blocks created them. */
1148 tidy_fallthru_edges ()
1152 for (i = 1; i < n_basic_blocks; i++)
1154 basic_block b = BASIC_BLOCK (i - 1);
1155 basic_block c = BASIC_BLOCK (i);
1158 /* We care about simple conditional or unconditional jumps with
1161 If we had a conditional branch to the next instruction when
1162 find_basic_blocks was called, then there will only be one
1163 out edge for the block which ended with the conditional
1164 branch (since we do not create duplicate edges).
1166 Furthermore, the edge will be marked as a fallthru because we
1167 merge the flags for the duplicate edges. So we do not want to
1168 check that the edge is not a FALLTHRU edge. */
1170 if ((s = b->succ) != NULL
1171 && ! (s->flags & EDGE_COMPLEX)
1172 && s->succ_next == NULL
1174 /* If the jump insn has side effects, we can't tidy the edge. */
1175 && (GET_CODE (b->end) != JUMP_INSN
1176 || onlyjump_p (b->end)))
1177 tidy_fallthru_edge (s, b, c);
1181 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1182 is back edge of syntactic loop. */
1185 back_edge_of_syntactic_loop_p (bb1, bb2)
1186 basic_block bb1, bb2;
1191 if (bb1->index > bb2->index)
1193 else if (bb1->index == bb2->index)
1196 for (insn = bb1->end; insn != bb2->head && count >= 0;
1197 insn = NEXT_INSN (insn))
1198 if (GET_CODE (insn) == NOTE)
1200 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1202 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1209 /* Split a (typically critical) edge. Return the new block.
1210 Abort on abnormal edges.
1212 ??? The code generally expects to be called on critical edges.
1213 The case of a block ending in an unconditional jump to a
1214 block with multiple predecessors is not handled optimally. */
1217 split_edge (edge_in)
1224 /* Abnormal edges cannot be split. */
1225 if ((edge_in->flags & EDGE_ABNORMAL) != 0)
1228 /* We are going to place the new block in front of edge destination.
1229 Avoid existence of fallthru predecessors. */
1230 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1234 for (e = edge_in->dest->pred; e; e = e->pred_next)
1235 if (e->flags & EDGE_FALLTHRU)
1239 force_nonfallthru (e);
1242 /* Create the basic block note.
1244 Where we place the note can have a noticeable impact on the generated
1245 code. Consider this cfg:
1255 If we need to insert an insn on the edge from block 0 to block 1,
1256 we want to ensure the instructions we insert are outside of any
1257 loop notes that physically sit between block 0 and block 1. Otherwise
1258 we confuse the loop optimizer into thinking the loop is a phony. */
1260 if (edge_in->dest != EXIT_BLOCK_PTR
1261 && PREV_INSN (edge_in->dest->head)
1262 && GET_CODE (PREV_INSN (edge_in->dest->head)) == NOTE
1263 && (NOTE_LINE_NUMBER (PREV_INSN (edge_in->dest->head))
1264 == NOTE_INSN_LOOP_BEG)
1265 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1266 before = PREV_INSN (edge_in->dest->head);
1267 else if (edge_in->dest != EXIT_BLOCK_PTR)
1268 before = edge_in->dest->head;
1272 bb = create_basic_block (edge_in->dest == EXIT_BLOCK_PTR ? n_basic_blocks
1273 : edge_in->dest->index, before, NULL);
1274 bb->count = edge_in->count;
1275 bb->frequency = EDGE_FREQUENCY (edge_in);
1277 /* ??? This info is likely going to be out of date very soon. */
1278 if (edge_in->dest->global_live_at_start)
1280 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1281 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1282 COPY_REG_SET (bb->global_live_at_start,
1283 edge_in->dest->global_live_at_start);
1284 COPY_REG_SET (bb->global_live_at_end,
1285 edge_in->dest->global_live_at_start);
1288 edge_out = make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1290 /* For non-fallthry edges, we must adjust the predecessor's
1291 jump instruction to target our new block. */
1292 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1294 if (!redirect_edge_and_branch (edge_in, bb))
1298 redirect_edge_succ (edge_in, bb);
1303 /* Queue instructions for insertion on an edge between two basic blocks.
1304 The new instructions and basic blocks (if any) will not appear in the
1305 CFG until commit_edge_insertions is called. */
1308 insert_insn_on_edge (pattern, e)
1312 /* We cannot insert instructions on an abnormal critical edge.
1313 It will be easier to find the culprit if we die now. */
1314 if ((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e))
1317 if (e->insns == NULL_RTX)
1320 push_to_sequence (e->insns);
1322 emit_insn (pattern);
1324 e->insns = get_insns ();
1328 /* Update the CFG for the instructions queued on edge E. */
1331 commit_one_edge_insertion (e, watch_calls)
1335 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1338 /* Pull the insns off the edge now since the edge might go away. */
1340 e->insns = NULL_RTX;
1342 /* Special case -- avoid inserting code between call and storing
1343 its return value. */
1344 if (watch_calls && (e->flags & EDGE_FALLTHRU) && !e->dest->pred->pred_next
1345 && e->src != ENTRY_BLOCK_PTR
1346 && GET_CODE (e->src->end) == CALL_INSN)
1348 rtx next = next_nonnote_insn (e->src->end);
1350 after = e->dest->head;
1351 /* The first insn after the call may be a stack pop, skip it. */
1353 && keep_with_call_p (next))
1356 next = next_nonnote_insn (next);
1360 if (!before && !after)
1362 /* Figure out where to put these things. If the destination has
1363 one predecessor, insert there. Except for the exit block. */
1364 if (e->dest->pred->pred_next == NULL && e->dest != EXIT_BLOCK_PTR)
1368 /* Get the location correct wrt a code label, and "nice" wrt
1369 a basic block note, and before everything else. */
1371 if (GET_CODE (tmp) == CODE_LABEL)
1372 tmp = NEXT_INSN (tmp);
1373 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1374 tmp = NEXT_INSN (tmp);
1375 if (tmp == bb->head)
1378 after = PREV_INSN (tmp);
1380 after = get_last_insn ();
1383 /* If the source has one successor and the edge is not abnormal,
1384 insert there. Except for the entry block. */
1385 else if ((e->flags & EDGE_ABNORMAL) == 0
1386 && e->src->succ->succ_next == NULL
1387 && e->src != ENTRY_BLOCK_PTR)
1391 /* It is possible to have a non-simple jump here. Consider a target
1392 where some forms of unconditional jumps clobber a register. This
1393 happens on the fr30 for example.
1395 We know this block has a single successor, so we can just emit
1396 the queued insns before the jump. */
1397 if (GET_CODE (bb->end) == JUMP_INSN)
1398 for (before = bb->end;
1399 GET_CODE (PREV_INSN (before)) == NOTE
1400 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1401 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1405 /* We'd better be fallthru, or we've lost track of what's what. */
1406 if ((e->flags & EDGE_FALLTHRU) == 0)
1412 /* Otherwise we must split the edge. */
1415 bb = split_edge (e);
1420 /* Now that we've found the spot, do the insertion. */
1424 emit_insns_before (insns, before);
1425 last = prev_nonnote_insn (before);
1428 last = emit_insns_after (insns, after);
1430 if (returnjump_p (last))
1432 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1433 This is not currently a problem because this only happens
1434 for the (single) epilogue, which already has a fallthru edge
1438 if (e->dest != EXIT_BLOCK_PTR
1439 || e->succ_next != NULL || (e->flags & EDGE_FALLTHRU) == 0)
1442 e->flags &= ~EDGE_FALLTHRU;
1443 emit_barrier_after (last);
1446 delete_insn (before);
1448 else if (GET_CODE (last) == JUMP_INSN)
1451 find_sub_basic_blocks (bb);
1454 /* Update the CFG for all queued instructions. */
1457 commit_edge_insertions ()
1462 #ifdef ENABLE_CHECKING
1463 verify_flow_info ();
1467 bb = ENTRY_BLOCK_PTR;
1472 for (e = bb->succ; e; e = next)
1474 next = e->succ_next;
1476 commit_one_edge_insertion (e, false);
1479 if (++i >= n_basic_blocks)
1481 bb = BASIC_BLOCK (i);
1485 /* Update the CFG for all queued instructions, taking special care of inserting
1486 code on edges between call and storing its return value. */
1489 commit_edge_insertions_watch_calls ()
1494 #ifdef ENABLE_CHECKING
1495 verify_flow_info ();
1499 bb = ENTRY_BLOCK_PTR;
1504 for (e = bb->succ; e; e = next)
1506 next = e->succ_next;
1508 commit_one_edge_insertion (e, true);
1511 if (++i >= n_basic_blocks)
1513 bb = BASIC_BLOCK (i);
1517 /* Print out one basic block with live information at start and end. */
1528 fprintf (outf, ";; Basic block %d, loop depth %d, count ",
1529 bb->index, bb->loop_depth);
1530 fprintf (outf, HOST_WIDEST_INT_PRINT_DEC, (HOST_WIDEST_INT) bb->count);
1533 fputs (";; Predecessors: ", outf);
1534 for (e = bb->pred; e; e = e->pred_next)
1535 dump_edge_info (outf, e, 0);
1538 fputs (";; Registers live at start:", outf);
1539 dump_regset (bb->global_live_at_start, outf);
1542 for (insn = bb->head, last = NEXT_INSN (bb->end); insn != last;
1543 insn = NEXT_INSN (insn))
1544 print_rtl_single (outf, insn);
1546 fputs (";; Registers live at end:", outf);
1547 dump_regset (bb->global_live_at_end, outf);
1550 fputs (";; Successors: ", outf);
1551 for (e = bb->succ; e; e = e->succ_next)
1552 dump_edge_info (outf, e, 1);
1560 dump_bb (bb, stderr);
1567 dump_bb (BASIC_BLOCK (n), stderr);
1570 /* Like print_rtl, but also print out live information for the start of each
1574 print_rtl_with_bb (outf, rtx_first)
1581 fprintf (outf, "(nil)\n");
1585 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1586 int max_uid = get_max_uid ();
1588 = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
1590 = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
1591 enum bb_state *in_bb_p
1592 = (enum bb_state *) xcalloc (max_uid, sizeof (enum bb_state));
1594 for (i = n_basic_blocks - 1; i >= 0; i--)
1596 basic_block bb = BASIC_BLOCK (i);
1599 start[INSN_UID (bb->head)] = bb;
1600 end[INSN_UID (bb->end)] = bb;
1601 for (x = bb->head; x != NULL_RTX; x = NEXT_INSN (x))
1603 enum bb_state state = IN_MULTIPLE_BB;
1605 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1607 in_bb_p[INSN_UID (x)] = state;
1614 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1619 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1621 fprintf (outf, ";; Start of basic block %d, registers live:",
1623 dump_regset (bb->global_live_at_start, outf);
1627 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1628 && GET_CODE (tmp_rtx) != NOTE
1629 && GET_CODE (tmp_rtx) != BARRIER)
1630 fprintf (outf, ";; Insn is not within a basic block\n");
1631 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1632 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1634 did_output = print_rtl_single (outf, tmp_rtx);
1636 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1638 fprintf (outf, ";; End of basic block %d, registers live:\n",
1640 dump_regset (bb->global_live_at_end, outf);
1653 if (current_function_epilogue_delay_list != 0)
1655 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1656 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1657 tmp_rtx = XEXP (tmp_rtx, 1))
1658 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1663 update_br_prob_note (bb)
1667 if (GET_CODE (bb->end) != JUMP_INSN)
1669 note = find_reg_note (bb->end, REG_BR_PROB, NULL_RTX);
1670 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1672 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1675 /* Verify the CFG consistency. This function check some CFG invariants and
1676 aborts when something is wrong. Hope that this function will help to
1677 convert many optimization passes to preserve CFG consistent.
1679 Currently it does following checks:
1681 - test head/end pointers
1682 - overlapping of basic blocks
1683 - edge list correctness
1684 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1685 - tails of basic blocks (ensure that boundary is necessary)
1686 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1687 and NOTE_INSN_BASIC_BLOCK
1688 - check that all insns are in the basic blocks
1689 (except the switch handling code, barriers and notes)
1690 - check that all returns are followed by barriers
1692 In future it can be extended check a lot of other stuff as well
1693 (reachability of basic blocks, life information, etc. etc.). */
1698 const int max_uid = get_max_uid ();
1699 const rtx rtx_first = get_insns ();
1700 rtx last_head = get_last_insn ();
1701 basic_block *bb_info, *last_visited;
1702 size_t *edge_checksum;
1704 int i, last_bb_num_seen, num_bb_notes, err = 0;
1706 bb_info = (basic_block *) xcalloc (max_uid, sizeof (basic_block));
1707 last_visited = (basic_block *) xcalloc (n_basic_blocks + 2,
1708 sizeof (basic_block));
1709 edge_checksum = (size_t *) xcalloc (n_basic_blocks + 2, sizeof (size_t));
1711 for (i = n_basic_blocks - 1; i >= 0; i--)
1713 basic_block bb = BASIC_BLOCK (i);
1714 rtx head = bb->head;
1717 /* Verify the end of the basic block is in the INSN chain. */
1718 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1724 error ("end insn %d for block %d not found in the insn stream",
1725 INSN_UID (end), bb->index);
1729 /* Work backwards from the end to the head of the basic block
1730 to verify the head is in the RTL chain. */
1731 for (; x != NULL_RTX; x = PREV_INSN (x))
1733 /* While walking over the insn chain, verify insns appear
1734 in only one basic block and initialize the BB_INFO array
1735 used by other passes. */
1736 if (bb_info[INSN_UID (x)] != NULL)
1738 error ("insn %d is in multiple basic blocks (%d and %d)",
1739 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1743 bb_info[INSN_UID (x)] = bb;
1750 error ("head insn %d for block %d not found in the insn stream",
1751 INSN_UID (head), bb->index);
1758 /* Now check the basic blocks (boundaries etc.) */
1759 for (i = n_basic_blocks - 1; i >= 0; i--)
1761 basic_block bb = BASIC_BLOCK (i);
1762 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1766 if (INSN_P (bb->end)
1767 && (note = find_reg_note (bb->end, REG_BR_PROB, NULL_RTX))
1768 && any_condjump_p (bb->end))
1770 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability)
1772 error ("verify_flow_info: REG_BR_PROB does not match cfg %i %i",
1773 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1779 error ("verify_flow_info: Wrong count of block %i %i",
1780 bb->index, (int)bb->count);
1783 if (bb->frequency < 0)
1785 error ("verify_flow_info: Wrong frequency of block %i %i",
1786 bb->index, bb->frequency);
1789 for (e = bb->succ; e; e = e->succ_next)
1791 if (last_visited [e->dest->index + 2] == bb)
1793 error ("verify_flow_info: Duplicate edge %i->%i",
1794 e->src->index, e->dest->index);
1797 if (e->probability < 0 || e->probability > REG_BR_PROB_BASE)
1799 error ("verify_flow_info: Wrong probability of edge %i->%i %i",
1800 e->src->index, e->dest->index, e->probability);
1805 error ("verify_flow_info: Wrong count of edge %i->%i %i",
1806 e->src->index, e->dest->index, (int)e->count);
1810 last_visited [e->dest->index + 2] = bb;
1812 if (e->flags & EDGE_FALLTHRU)
1815 if ((e->flags & ~EDGE_DFS_BACK) == 0)
1818 if (e->flags & EDGE_ABNORMAL_CALL)
1821 if (e->flags & EDGE_EH)
1823 else if (e->flags & EDGE_ABNORMAL)
1826 if ((e->flags & EDGE_FALLTHRU)
1827 && e->src != ENTRY_BLOCK_PTR
1828 && e->dest != EXIT_BLOCK_PTR)
1832 if (e->src->index + 1 != e->dest->index)
1835 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
1836 e->src->index, e->dest->index);
1840 for (insn = NEXT_INSN (e->src->end); insn != e->dest->head;
1841 insn = NEXT_INSN (insn))
1842 if (GET_CODE (insn) == BARRIER
1843 #ifndef CASE_DROPS_THROUGH
1846 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
1850 error ("verify_flow_info: Incorrect fallthru %i->%i",
1851 e->src->index, e->dest->index);
1852 fatal_insn ("wrong insn in the fallthru edge", insn);
1859 error ("verify_flow_info: Basic block %d succ edge is corrupted",
1861 fprintf (stderr, "Predecessor: ");
1862 dump_edge_info (stderr, e, 0);
1863 fprintf (stderr, "\nSuccessor: ");
1864 dump_edge_info (stderr, e, 1);
1865 fprintf (stderr, "\n");
1869 edge_checksum[e->dest->index + 2] += (size_t) e;
1872 if (n_eh && GET_CODE (PATTERN (bb->end)) != RESX
1873 && !find_reg_note (bb->end, REG_EH_REGION, NULL_RTX))
1875 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
1879 && (GET_CODE (bb->end) != JUMP_INSN
1880 || (n_branch > 1 && (any_uncondjump_p (bb->end)
1881 || any_condjump_p (bb->end)))))
1883 error ("Too many outgoing branch edges from bb %i", bb->index);
1886 if (n_fallthru && any_uncondjump_p (bb->end))
1888 error ("Fallthru edge after unconditional jump %i", bb->index);
1891 if (n_branch != 1 && any_uncondjump_p (bb->end))
1893 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
1896 if (n_branch != 1 && any_condjump_p (bb->end)
1897 && JUMP_LABEL (bb->end) != BASIC_BLOCK (bb->index + 1)->head)
1899 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
1902 if (n_call && GET_CODE (bb->end) != CALL_INSN)
1904 error ("Call edges for non-call insn in bb %i", bb->index);
1908 && (GET_CODE (bb->end) != CALL_INSN && n_call != n_abnormal)
1909 && (GET_CODE (bb->end) != JUMP_INSN
1910 || any_condjump_p (bb->end)
1911 || any_uncondjump_p (bb->end)))
1913 error ("Abnormal edges for no purpose in bb %i", bb->index);
1921 /* Ensure existence of barrier in BB with no fallthru edges. */
1922 for (insn = bb->end; !insn || GET_CODE (insn) != BARRIER;
1923 insn = NEXT_INSN (insn))
1925 || (GET_CODE (insn) == NOTE
1926 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
1928 error ("missing barrier after block %i", bb->index);
1934 for (e = bb->pred; e; e = e->pred_next)
1938 error ("basic block %d pred edge is corrupted", bb->index);
1939 fputs ("Predecessor: ", stderr);
1940 dump_edge_info (stderr, e, 0);
1941 fputs ("\nSuccessor: ", stderr);
1942 dump_edge_info (stderr, e, 1);
1943 fputc ('\n', stderr);
1946 edge_checksum[e->dest->index + 2] -= (size_t) e;
1949 for (x = bb->head; x != NEXT_INSN (bb->end); x = NEXT_INSN (x))
1950 if (basic_block_for_insn && BLOCK_FOR_INSN (x) != bb)
1953 if (! BLOCK_FOR_INSN (x))
1955 ("insn %d inside basic block %d but block_for_insn is NULL",
1956 INSN_UID (x), bb->index);
1959 ("insn %d inside basic block %d but block_for_insn is %i",
1960 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
1965 /* OK pointers are correct. Now check the header of basic
1966 block. It ought to contain optional CODE_LABEL followed
1967 by NOTE_BASIC_BLOCK. */
1969 if (GET_CODE (x) == CODE_LABEL)
1973 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1981 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
1983 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
1989 /* Do checks for empty blocks her. e */
1992 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
1994 if (NOTE_INSN_BASIC_BLOCK_P (x))
1996 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
1997 INSN_UID (x), bb->index);
2004 if (GET_CODE (x) == JUMP_INSN
2005 || GET_CODE (x) == CODE_LABEL
2006 || GET_CODE (x) == BARRIER)
2008 error ("in basic block %d:", bb->index);
2009 fatal_insn ("flow control insn inside a basic block", x);
2014 /* Complete edge checksumming for ENTRY and EXIT. */
2018 for (e = ENTRY_BLOCK_PTR->succ; e ; e = e->succ_next)
2019 edge_checksum[e->dest->index + 2] += (size_t) e;
2021 for (e = EXIT_BLOCK_PTR->pred; e ; e = e->pred_next)
2022 edge_checksum[e->dest->index + 2] -= (size_t) e;
2025 for (i = -2; i < n_basic_blocks; ++i)
2026 if (edge_checksum[i + 2])
2028 error ("basic block %i edge lists are corrupted", i);
2032 last_bb_num_seen = -1;
2034 for (x = rtx_first; x; x = NEXT_INSN (x))
2036 if (NOTE_INSN_BASIC_BLOCK_P (x))
2038 basic_block bb = NOTE_BASIC_BLOCK (x);
2041 if (bb->index != last_bb_num_seen + 1)
2042 internal_error ("basic blocks not numbered consecutively");
2044 last_bb_num_seen = bb->index;
2047 if (!bb_info[INSN_UID (x)])
2049 switch (GET_CODE (x))
2056 /* An addr_vec is placed outside any block block. */
2058 && GET_CODE (NEXT_INSN (x)) == JUMP_INSN
2059 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2060 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2063 /* But in any case, non-deletable labels can appear anywhere. */
2067 fatal_insn ("insn outside basic block", x);
2072 && GET_CODE (x) == JUMP_INSN
2073 && returnjump_p (x) && ! condjump_p (x)
2074 && ! (NEXT_INSN (x) && GET_CODE (NEXT_INSN (x)) == BARRIER))
2075 fatal_insn ("return not followed by barrier", x);
2078 if (num_bb_notes != n_basic_blocks)
2080 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2081 num_bb_notes, n_basic_blocks);
2084 internal_error ("verify_flow_info failed");
2088 free (last_visited);
2089 free (edge_checksum);
2092 /* Assume that the preceding pass has possibly eliminated jump instructions
2093 or converted the unconditional jumps. Eliminate the edges from CFG.
2094 Return true if any edges are eliminated. */
2097 purge_dead_edges (bb)
2101 rtx insn = bb->end, note;
2102 bool purged = false;
2104 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2105 if (GET_CODE (insn) == INSN
2106 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2110 if (! may_trap_p (PATTERN (insn))
2111 || ((eqnote = find_reg_equal_equiv_note (insn))
2112 && ! may_trap_p (XEXP (eqnote, 0))))
2113 remove_note (insn, note);
2116 /* Cleanup abnormal edges caused by throwing insns that have been
2118 if (! can_throw_internal (bb->end))
2119 for (e = bb->succ; e; e = next)
2121 next = e->succ_next;
2122 if (e->flags & EDGE_EH)
2125 bb->flags |= BB_DIRTY;
2130 if (GET_CODE (insn) == JUMP_INSN)
2135 /* We do care only about conditional jumps and simplejumps. */
2136 if (!any_condjump_p (insn)
2137 && !returnjump_p (insn)
2138 && !simplejump_p (insn))
2141 /* Branch probability/prediction notes are defined only for
2142 condjumps. We've possibly turned condjump into simplejump. */
2143 if (simplejump_p (insn))
2145 note = find_reg_note (insn, REG_BR_PROB, NULL);
2147 remove_note (insn, note);
2148 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2149 remove_note (insn, note);
2152 for (e = bb->succ; e; e = next)
2154 next = e->succ_next;
2156 /* Avoid abnormal flags to leak from computed jumps turned
2157 into simplejumps. */
2159 e->flags &= ~EDGE_ABNORMAL;
2161 /* Check purposes we can have edge. */
2162 if ((e->flags & EDGE_FALLTHRU)
2163 && any_condjump_p (insn))
2165 else if (e->dest != EXIT_BLOCK_PTR
2166 && e->dest->head == JUMP_LABEL (insn))
2168 else if (e->dest == EXIT_BLOCK_PTR
2169 && returnjump_p (insn))
2172 bb->flags |= BB_DIRTY;
2177 if (!bb->succ || !purged)
2181 fprintf (rtl_dump_file, "Purged edges from bb %i\n", bb->index);
2186 /* Redistribute probabilities. */
2187 if (!bb->succ->succ_next)
2189 bb->succ->probability = REG_BR_PROB_BASE;
2190 bb->succ->count = bb->count;
2194 note = find_reg_note (insn, REG_BR_PROB, NULL);
2198 b = BRANCH_EDGE (bb);
2199 f = FALLTHRU_EDGE (bb);
2200 b->probability = INTVAL (XEXP (note, 0));
2201 f->probability = REG_BR_PROB_BASE - b->probability;
2202 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2203 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2209 /* If we don't see a jump insn, we don't know exactly why the block would
2210 have been broken at this point. Look for a simple, non-fallthru edge,
2211 as these are only created by conditional branches. If we find such an
2212 edge we know that there used to be a jump here and can then safely
2213 remove all non-fallthru edges. */
2214 for (e = bb->succ; e && (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU));
2221 for (e = bb->succ; e; e = next)
2223 next = e->succ_next;
2224 if (!(e->flags & EDGE_FALLTHRU))
2226 bb->flags |= BB_DIRTY;
2232 if (!bb->succ || bb->succ->succ_next)
2235 bb->succ->probability = REG_BR_PROB_BASE;
2236 bb->succ->count = bb->count;
2239 fprintf (rtl_dump_file, "Purged non-fallthru edges from bb %i\n",
2244 /* Search all basic blocks for potentially dead edges and purge them. Return
2245 true if some edge has been eliminated. */
2248 purge_all_dead_edges (update_life_p)
2251 int i, purged = false;
2256 blocks = sbitmap_alloc (n_basic_blocks);
2257 sbitmap_zero (blocks);
2260 for (i = 0; i < n_basic_blocks; i++)
2262 bool purged_here = purge_dead_edges (BASIC_BLOCK (i));
2264 purged |= purged_here;
2265 if (purged_here && update_life_p)
2266 SET_BIT (blocks, i);
2269 if (update_life_p && purged)
2270 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2271 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2272 | PROP_KILL_DEAD_CODE);
2275 sbitmap_free (blocks);