1 /* Control flow graph manipulation code for GNU compiler.
2 Copyright (C) 1987, 1988, 1992, 1993, 1994, 1995, 1996, 1997, 1998,
3 1999, 2000, 2001, 2002, 2003, 2004 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 - Basic CFG/RTL manipulation API documented in cfghooks.h
27 - CFG-aware instruction chain manipulation
28 delete_insn, delete_insn_chain
29 - Edge splitting and committing to edges
30 insert_insn_on_edge, commit_edge_insertions
31 - CFG updating after insn simplification
32 purge_dead_edges, purge_all_dead_edges
34 Functions not supposed for generic use:
35 - Infrastructure to determine quickly basic block for insn
36 compute_bb_for_insn, update_bb_for_insn, set_block_for_insn,
37 - Edge redirection with updating and optimizing of insn chain
38 block_label, tidy_fallthru_edge, force_nonfallthru */
42 #include "coretypes.h"
46 #include "hard-reg-set.h"
47 #include "basic-block.h"
56 #include "insn-config.h"
57 #include "cfglayout.h"
62 /* The labels mentioned in non-jump rtl. Valid during find_basic_blocks. */
63 /* ??? Should probably be using LABEL_NUSES instead. It would take a
64 bit of surgery to be able to use or co-opt the routines in jump. */
67 static int can_delete_note_p (rtx);
68 static int can_delete_label_p (rtx);
69 static void commit_one_edge_insertion (edge, int);
70 static rtx last_loop_beg_note (rtx);
71 static bool back_edge_of_syntactic_loop_p (basic_block, basic_block);
72 static basic_block rtl_split_edge (edge);
73 static bool rtl_move_block_after (basic_block, basic_block);
74 static int rtl_verify_flow_info (void);
75 static basic_block cfg_layout_split_block (basic_block, void *);
76 static edge cfg_layout_redirect_edge_and_branch (edge, basic_block);
77 static basic_block cfg_layout_redirect_edge_and_branch_force (edge, basic_block);
78 static void cfg_layout_delete_block (basic_block);
79 static void rtl_delete_block (basic_block);
80 static basic_block rtl_redirect_edge_and_branch_force (edge, basic_block);
81 static edge rtl_redirect_edge_and_branch (edge, basic_block);
82 static basic_block rtl_split_block (basic_block, void *);
83 static void rtl_dump_bb (basic_block, FILE *, int);
84 static int rtl_verify_flow_info_1 (void);
85 static void mark_killed_regs (rtx, rtx, void *);
86 static void rtl_make_forwarder_block (edge);
88 /* Return true if NOTE is not one of the ones that must be kept paired,
89 so that we may simply delete it. */
92 can_delete_note_p (rtx note)
94 return (NOTE_LINE_NUMBER (note) == NOTE_INSN_DELETED
95 || NOTE_LINE_NUMBER (note) == NOTE_INSN_BASIC_BLOCK
96 || NOTE_LINE_NUMBER (note) == NOTE_INSN_UNLIKELY_EXECUTED_CODE);
99 /* True if a given label can be deleted. */
102 can_delete_label_p (rtx label)
104 return (!LABEL_PRESERVE_P (label)
105 /* User declared labels must be preserved. */
106 && LABEL_NAME (label) == 0
107 && !in_expr_list_p (forced_labels, label)
108 && !in_expr_list_p (label_value_list, label));
111 /* Delete INSN by patching it out. Return the next insn. */
114 delete_insn (rtx insn)
116 rtx next = NEXT_INSN (insn);
118 bool really_delete = true;
122 /* Some labels can't be directly removed from the INSN chain, as they
123 might be references via variables, constant pool etc.
124 Convert them to the special NOTE_INSN_DELETED_LABEL note. */
125 if (! can_delete_label_p (insn))
127 const char *name = LABEL_NAME (insn);
129 really_delete = false;
130 PUT_CODE (insn, NOTE);
131 NOTE_LINE_NUMBER (insn) = NOTE_INSN_DELETED_LABEL;
132 NOTE_DELETED_LABEL_NAME (insn) = name;
135 remove_node_from_expr_list (insn, &nonlocal_goto_handler_labels);
140 /* If this insn has already been deleted, something is very wrong. */
141 gcc_assert (!INSN_DELETED_P (insn));
143 INSN_DELETED_P (insn) = 1;
146 /* If deleting a jump, decrement the use count of the label. Deleting
147 the label itself should happen in the normal course of block merging. */
150 && LABEL_P (JUMP_LABEL (insn)))
151 LABEL_NUSES (JUMP_LABEL (insn))--;
153 /* Also if deleting an insn that references a label. */
156 while ((note = find_reg_note (insn, REG_LABEL, NULL_RTX)) != NULL_RTX
157 && LABEL_P (XEXP (note, 0)))
159 LABEL_NUSES (XEXP (note, 0))--;
160 remove_note (insn, note);
165 && (GET_CODE (PATTERN (insn)) == ADDR_VEC
166 || GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC))
168 rtx pat = PATTERN (insn);
169 int diff_vec_p = GET_CODE (PATTERN (insn)) == ADDR_DIFF_VEC;
170 int len = XVECLEN (pat, diff_vec_p);
173 for (i = 0; i < len; i++)
175 rtx label = XEXP (XVECEXP (pat, diff_vec_p, i), 0);
177 /* When deleting code in bulk (e.g. removing many unreachable
178 blocks) we can delete a label that's a target of the vector
179 before deleting the vector itself. */
181 LABEL_NUSES (label)--;
188 /* Like delete_insn but also purge dead edges from BB. */
190 delete_insn_and_edges (rtx insn)
196 && BLOCK_FOR_INSN (insn)
197 && BB_END (BLOCK_FOR_INSN (insn)) == insn)
199 x = delete_insn (insn);
201 purge_dead_edges (BLOCK_FOR_INSN (insn));
205 /* Unlink a chain of insns between START and FINISH, leaving notes
206 that must be paired. */
209 delete_insn_chain (rtx start, rtx finish)
213 /* Unchain the insns one by one. It would be quicker to delete all of these
214 with a single unchaining, rather than one at a time, but we need to keep
218 next = NEXT_INSN (start);
219 if (NOTE_P (start) && !can_delete_note_p (start))
222 next = delete_insn (start);
230 /* Like delete_insn but also purge dead edges from BB. */
232 delete_insn_chain_and_edges (rtx first, rtx last)
237 && BLOCK_FOR_INSN (last)
238 && BB_END (BLOCK_FOR_INSN (last)) == 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.
251 AFTER is the basic block we should be put after. */
254 create_basic_block_structure (rtx head, rtx end, rtx bb_note, basic_block after)
259 && (bb = NOTE_BASIC_BLOCK (bb_note)) != NULL
262 /* If we found an existing note, thread it back onto the chain. */
270 after = PREV_INSN (head);
274 if (after != bb_note && NEXT_INSN (after) != bb_note)
275 reorder_insns_nobb (bb_note, bb_note, after);
279 /* Otherwise we must create a note and a basic block structure. */
285 = emit_note_after (NOTE_INSN_BASIC_BLOCK, get_last_insn ());
286 else if (LABEL_P (head) && end)
288 bb_note = emit_note_after (NOTE_INSN_BASIC_BLOCK, head);
294 bb_note = emit_note_before (NOTE_INSN_BASIC_BLOCK, head);
300 NOTE_BASIC_BLOCK (bb_note) = bb;
303 /* Always include the bb note in the block. */
304 if (NEXT_INSN (end) == bb_note)
309 bb->index = last_basic_block++;
311 link_block (bb, after);
312 BASIC_BLOCK (bb->index) = bb;
313 update_bb_for_insn (bb);
314 BB_SET_PARTITION (bb, BB_UNPARTITIONED);
316 /* Tag the block so that we know it has been used when considering
317 other basic block notes. */
323 /* Create new basic block consisting of instructions in between HEAD and END
324 and place it to the BB chain after block AFTER. END can be NULL in to
325 create new empty basic block before HEAD. Both END and HEAD can be NULL to
326 create basic block at the end of INSN chain. */
329 rtl_create_basic_block (void *headp, void *endp, basic_block after)
331 rtx head = headp, end = endp;
334 /* Grow the basic block array if needed. */
335 if ((size_t) last_basic_block >= VARRAY_SIZE (basic_block_info))
337 size_t new_size = last_basic_block + (last_basic_block + 3) / 4;
338 VARRAY_GROW (basic_block_info, new_size);
343 bb = create_basic_block_structure (head, end, NULL, after);
349 cfg_layout_create_basic_block (void *head, void *end, basic_block after)
351 basic_block newbb = rtl_create_basic_block (head, end, after);
353 initialize_bb_rbi (newbb);
357 /* Delete the insns in a (non-live) block. We physically delete every
358 non-deleted-note insn, and update the flow graph appropriately.
360 Return nonzero if we deleted an exception handler. */
362 /* ??? Preserving all such notes strikes me as wrong. It would be nice
363 to post-process the stream to remove empty blocks, loops, ranges, etc. */
366 rtl_delete_block (basic_block b)
370 /* If the head of this block is a CODE_LABEL, then it might be the
371 label for an exception handler which can't be reached. We need
372 to remove the label from the exception_handler_label list. */
375 maybe_remove_eh_handler (insn);
377 /* Include any jump table following the basic block. */
379 if (tablejump_p (end, NULL, &tmp))
382 /* Include any barrier that may follow the basic block. */
383 tmp = next_nonnote_insn (end);
384 if (tmp && BARRIER_P (tmp))
387 /* Selectively delete the entire chain. */
389 delete_insn_chain (insn, end);
392 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
395 compute_bb_for_insn (void)
401 rtx end = BB_END (bb);
404 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
406 BLOCK_FOR_INSN (insn) = bb;
413 /* Release the basic_block_for_insn array. */
416 free_bb_for_insn (void)
419 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
420 if (!BARRIER_P (insn))
421 BLOCK_FOR_INSN (insn) = NULL;
424 /* Return RTX to emit after when we want to emit code on the entry of function. */
426 entry_of_function (void)
428 return (n_basic_blocks ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
431 /* Update insns block within BB. */
434 update_bb_for_insn (basic_block bb)
438 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
440 if (!BARRIER_P (insn))
441 set_block_for_insn (insn, bb);
442 if (insn == BB_END (bb))
447 /* Creates a new basic block just after basic block B by splitting
448 everything after specified instruction I. */
451 rtl_split_block (basic_block bb, void *insnp)
460 insn = first_insn_after_basic_block_note (bb);
463 insn = PREV_INSN (insn);
465 insn = get_last_insn ();
468 /* We probably should check type of the insn so that we do not create
469 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
471 if (insn == BB_END (bb))
472 emit_note_after (NOTE_INSN_DELETED, insn);
474 /* Create the new basic block. */
475 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
476 BB_COPY_PARTITION (new_bb, bb);
479 /* Redirect the outgoing edges. */
480 new_bb->succs = bb->succs;
482 FOR_EACH_EDGE (e, ei, new_bb->succs)
485 if (bb->global_live_at_start)
487 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (®_obstack);
488 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (®_obstack);
489 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
491 /* We now have to calculate which registers are live at the end
492 of the split basic block and at the start of the new basic
493 block. Start with those registers that are known to be live
494 at the end of the original basic block and get
495 propagate_block to determine which registers are live. */
496 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
497 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
498 COPY_REG_SET (bb->global_live_at_end,
499 new_bb->global_live_at_start);
500 #ifdef HAVE_conditional_execution
501 /* In the presence of conditional execution we are not able to update
502 liveness precisely. */
503 if (reload_completed)
505 bb->flags |= BB_DIRTY;
506 new_bb->flags |= BB_DIRTY;
514 /* Blocks A and B are to be merged into a single block A. The insns
515 are already contiguous. */
518 rtl_merge_blocks (basic_block a, basic_block b)
520 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
521 rtx del_first = NULL_RTX, del_last = NULL_RTX;
524 /* If there was a CODE_LABEL beginning B, delete it. */
525 if (LABEL_P (b_head))
527 /* Detect basic blocks with nothing but a label. This can happen
528 in particular at the end of a function. */
532 del_first = del_last = b_head;
533 b_head = NEXT_INSN (b_head);
536 /* Delete the basic block note and handle blocks containing just that
538 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
546 b_head = NEXT_INSN (b_head);
549 /* If there was a jump out of A, delete it. */
554 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
556 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
557 || prev == BB_HEAD (a))
563 /* If this was a conditional jump, we need to also delete
564 the insn that set cc0. */
565 if (only_sets_cc0_p (prev))
569 prev = prev_nonnote_insn (prev);
576 a_end = PREV_INSN (del_first);
578 else if (BARRIER_P (NEXT_INSN (a_end)))
579 del_first = NEXT_INSN (a_end);
581 /* Delete everything marked above as well as crap that might be
582 hanging out between the two blocks. */
584 delete_insn_chain (del_first, del_last);
586 /* Reassociate the insns of B with A. */
591 for (x = a_end; x != b_end; x = NEXT_INSN (x))
592 set_block_for_insn (x, a);
594 set_block_for_insn (b_end, a);
602 /* Return true when block A and B can be merged. */
604 rtl_can_merge_blocks (basic_block a,basic_block b)
606 /* If we are partitioning hot/cold basic blocks, we don't want to
607 mess up unconditional or indirect jumps that cross between hot
610 Basic block partitioning may result in some jumps that appear to
611 be optimizable (or blocks that appear to be mergeable), but which really
612 must be left untouched (they are required to make it safely across
613 partition boundaries). See the comments at the top of
614 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
616 if (flag_reorder_blocks_and_partition
617 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
618 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
619 || BB_PARTITION (a) != BB_PARTITION (b)))
622 /* There must be exactly one edge in between the blocks. */
623 return (EDGE_COUNT (a->succs) == 1
624 && EDGE_SUCC (a, 0)->dest == b
625 && EDGE_COUNT (b->preds) == 1
627 /* Must be simple edge. */
628 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
630 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
631 /* If the jump insn has side effects,
632 we can't kill the edge. */
633 && (!JUMP_P (BB_END (a))
635 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
638 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
642 block_label (basic_block block)
644 if (block == EXIT_BLOCK_PTR)
647 if (!LABEL_P (BB_HEAD (block)))
649 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
652 return BB_HEAD (block);
655 /* Attempt to perform edge redirection by replacing possibly complex jump
656 instruction by unconditional jump or removing jump completely. This can
657 apply only if all edges now point to the same block. The parameters and
658 return values are equivalent to redirect_edge_and_branch. */
661 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
663 basic_block src = e->src;
664 rtx insn = BB_END (src), kill_from;
670 /* If we are partitioning hot/cold basic blocks, we don't want to
671 mess up unconditional or indirect jumps that cross between hot
674 Basic block partitioning may result in some jumps that appear to
675 be optimizable (or blocks that appear to be mergeable), but which really
676 must be left untouched (they are required to make it safely across
677 partition boundaries). See the comments at the top of
678 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
680 if (flag_reorder_blocks_and_partition
681 && (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
682 || BB_PARTITION (src) != BB_PARTITION (target)))
685 /* Verify that all targets will be TARGET. */
686 FOR_EACH_EDGE (tmp, ei, src->succs)
687 if (tmp->dest != target && tmp != e)
690 if (tmp || !onlyjump_p (insn))
692 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
695 /* Avoid removing branch with side effects. */
696 set = single_set (insn);
697 if (!set || side_effects_p (set))
700 /* In case we zap a conditional jump, we'll need to kill
701 the cc0 setter too. */
704 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
705 kill_from = PREV_INSN (insn);
708 /* See if we can create the fallthru edge. */
709 if (in_cfglayout || can_fallthru (src, target))
712 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
715 /* Selectively unlink whole insn chain. */
718 rtx insn = src->rbi->footer;
720 delete_insn_chain (kill_from, BB_END (src));
722 /* Remove barriers but keep jumptables. */
725 if (BARRIER_P (insn))
727 if (PREV_INSN (insn))
728 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
730 src->rbi->footer = NEXT_INSN (insn);
731 if (NEXT_INSN (insn))
732 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
736 insn = NEXT_INSN (insn);
740 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
743 /* If this already is simplejump, redirect it. */
744 else if (simplejump_p (insn))
746 if (e->dest == target)
749 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
750 INSN_UID (insn), e->dest->index, target->index);
751 if (!redirect_jump (insn, block_label (target), 0))
753 gcc_assert (target == EXIT_BLOCK_PTR);
758 /* Cannot do anything for target exit block. */
759 else if (target == EXIT_BLOCK_PTR)
762 /* Or replace possibly complicated jump insn by simple jump insn. */
765 rtx target_label = block_label (target);
766 rtx barrier, label, table;
768 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
769 JUMP_LABEL (BB_END (src)) = target_label;
770 LABEL_NUSES (target_label)++;
772 fprintf (dump_file, "Replacing insn %i by jump %i\n",
773 INSN_UID (insn), INSN_UID (BB_END (src)));
776 delete_insn_chain (kill_from, insn);
778 /* Recognize a tablejump that we are converting to a
779 simple jump and remove its associated CODE_LABEL
780 and ADDR_VEC or ADDR_DIFF_VEC. */
781 if (tablejump_p (insn, &label, &table))
782 delete_insn_chain (label, table);
784 barrier = next_nonnote_insn (BB_END (src));
785 if (!barrier || !BARRIER_P (barrier))
786 emit_barrier_after (BB_END (src));
789 if (barrier != NEXT_INSN (BB_END (src)))
791 /* Move the jump before barrier so that the notes
792 which originally were or were created before jump table are
793 inside the basic block. */
794 rtx new_insn = BB_END (src);
797 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
798 tmp = NEXT_INSN (tmp))
799 set_block_for_insn (tmp, src);
801 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
802 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
804 NEXT_INSN (new_insn) = barrier;
805 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
807 PREV_INSN (new_insn) = PREV_INSN (barrier);
808 PREV_INSN (barrier) = new_insn;
813 /* Keep only one edge out and set proper flags. */
814 while (EDGE_COUNT (src->succs) > 1)
817 e = EDGE_SUCC (src, 0);
819 e->flags = EDGE_FALLTHRU;
823 e->probability = REG_BR_PROB_BASE;
824 e->count = src->count;
826 /* We don't want a block to end on a line-number note since that has
827 the potential of changing the code between -g and not -g. */
828 while (NOTE_P (BB_END (e->src))
829 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
830 delete_insn (BB_END (e->src));
832 if (e->dest != target)
833 redirect_edge_succ (e, target);
838 /* Return last loop_beg note appearing after INSN, before start of next
839 basic block. Return INSN if there are no such notes.
841 When emitting jump to redirect a fallthru edge, it should always appear
842 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
843 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
847 last_loop_beg_note (rtx insn)
851 for (insn = NEXT_INSN (insn); insn && NOTE_P (insn)
852 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
853 insn = NEXT_INSN (insn))
854 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
860 /* Redirect edge representing branch of (un)conditional jump or tablejump,
863 redirect_branch_edge (edge e, basic_block target)
866 rtx old_label = BB_HEAD (e->dest);
867 basic_block src = e->src;
868 rtx insn = BB_END (src);
870 /* We can only redirect non-fallthru edges of jump insn. */
871 if (e->flags & EDGE_FALLTHRU)
873 else if (!JUMP_P (insn))
876 /* Recognize a tablejump and adjust all matching cases. */
877 if (tablejump_p (insn, NULL, &tmp))
881 rtx new_label = block_label (target);
883 if (target == EXIT_BLOCK_PTR)
885 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
886 vec = XVEC (PATTERN (tmp), 0);
888 vec = XVEC (PATTERN (tmp), 1);
890 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
891 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
893 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
894 --LABEL_NUSES (old_label);
895 ++LABEL_NUSES (new_label);
898 /* Handle casesi dispatch insns. */
899 if ((tmp = single_set (insn)) != NULL
900 && SET_DEST (tmp) == pc_rtx
901 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
902 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
903 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
905 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
907 --LABEL_NUSES (old_label);
908 ++LABEL_NUSES (new_label);
913 /* ?? We may play the games with moving the named labels from
914 one basic block to the other in case only one computed_jump is
916 if (computed_jump_p (insn)
917 /* A return instruction can't be redirected. */
918 || returnjump_p (insn))
921 /* If the insn doesn't go where we think, we're confused. */
922 gcc_assert (JUMP_LABEL (insn) == old_label);
924 /* If the substitution doesn't succeed, die. This can happen
925 if the back end emitted unrecognizable instructions or if
926 target is exit block on some arches. */
927 if (!redirect_jump (insn, block_label (target), 0))
929 gcc_assert (target == EXIT_BLOCK_PTR);
935 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
936 e->src->index, e->dest->index, target->index);
938 if (e->dest != target)
939 e = redirect_edge_succ_nodup (e, target);
943 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
944 expense of adding new instructions or reordering basic blocks.
946 Function can be also called with edge destination equivalent to the TARGET.
947 Then it should try the simplifications and do nothing if none is possible.
949 Return edge representing the branch if transformation succeeded. Return NULL
951 We still return NULL in case E already destinated TARGET and we didn't
952 managed to simplify instruction stream. */
955 rtl_redirect_edge_and_branch (edge e, basic_block target)
958 basic_block src = e->src;
960 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
963 if (e->dest == target)
966 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
968 src->flags |= BB_DIRTY;
972 ret = redirect_branch_edge (e, target);
976 src->flags |= BB_DIRTY;
980 /* Like force_nonfallthru below, but additionally performs redirection
981 Used by redirect_edge_and_branch_force. */
984 force_nonfallthru_and_redirect (edge e, basic_block target)
986 basic_block jump_block, new_bb = NULL, src = e->src;
989 int abnormal_edge_flags = 0;
991 /* In the case the last instruction is conditional jump to the next
992 instruction, first redirect the jump itself and then continue
993 by creating a basic block afterwards to redirect fallthru edge. */
994 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
995 && any_condjump_p (BB_END (e->src))
996 /* When called from cfglayout, fallthru edges do not
997 necessarily go to the next block. */
998 && e->src->next_bb == e->dest
999 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1002 edge b = unchecked_make_edge (e->src, target, 0);
1005 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1006 gcc_assert (redirected);
1008 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1011 int prob = INTVAL (XEXP (note, 0));
1013 b->probability = prob;
1014 b->count = e->count * prob / REG_BR_PROB_BASE;
1015 e->probability -= e->probability;
1016 e->count -= b->count;
1017 if (e->probability < 0)
1024 if (e->flags & EDGE_ABNORMAL)
1026 /* Irritating special case - fallthru edge to the same block as abnormal
1028 We can't redirect abnormal edge, but we still can split the fallthru
1029 one and create separate abnormal edge to original destination.
1030 This allows bb-reorder to make such edge non-fallthru. */
1031 gcc_assert (e->dest == target);
1032 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1033 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1037 gcc_assert (e->flags & EDGE_FALLTHRU);
1038 if (e->src == ENTRY_BLOCK_PTR)
1040 /* We can't redirect the entry block. Create an empty block
1041 at the start of the function which we use to add the new
1047 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1049 /* Change the existing edge's source to be the new block, and add
1050 a new edge from the entry block to the new block. */
1052 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1056 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1066 VEC_safe_push (edge, bb->succs, e);
1067 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1071 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1073 /* Create the new structures. */
1075 /* If the old block ended with a tablejump, skip its table
1076 by searching forward from there. Otherwise start searching
1077 forward from the last instruction of the old block. */
1078 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1079 note = BB_END (e->src);
1081 /* Position the new block correctly relative to loop notes. */
1082 note = last_loop_beg_note (note);
1083 note = NEXT_INSN (note);
1085 jump_block = create_basic_block (note, NULL, e->src);
1086 jump_block->count = e->count;
1087 jump_block->frequency = EDGE_FREQUENCY (e);
1088 jump_block->loop_depth = target->loop_depth;
1090 if (target->global_live_at_start)
1092 jump_block->global_live_at_start
1093 = OBSTACK_ALLOC_REG_SET (®_obstack);
1094 jump_block->global_live_at_end
1095 = OBSTACK_ALLOC_REG_SET (®_obstack);
1096 COPY_REG_SET (jump_block->global_live_at_start,
1097 target->global_live_at_start);
1098 COPY_REG_SET (jump_block->global_live_at_end,
1099 target->global_live_at_start);
1102 /* Make sure new block ends up in correct hot/cold section. */
1104 BB_COPY_PARTITION (jump_block, e->src);
1105 if (flag_reorder_blocks_and_partition
1106 && targetm.have_named_sections)
1108 if (BB_PARTITION (jump_block) == BB_COLD_PARTITION)
1110 rtx bb_note, new_note;
1111 for (bb_note = BB_HEAD (jump_block);
1112 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1113 bb_note = NEXT_INSN (bb_note))
1114 if (NOTE_P (bb_note)
1115 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1117 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1119 NOTE_BASIC_BLOCK (new_note) = jump_block;
1121 if (JUMP_P (BB_END (jump_block))
1122 && !any_condjump_p (BB_END (jump_block))
1123 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1124 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1125 (REG_CROSSING_JUMP, NULL_RTX,
1126 REG_NOTES (BB_END (jump_block)));
1130 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1131 new_edge->probability = e->probability;
1132 new_edge->count = e->count;
1134 /* Redirect old edge. */
1135 redirect_edge_pred (e, jump_block);
1136 e->probability = REG_BR_PROB_BASE;
1138 new_bb = jump_block;
1141 jump_block = e->src;
1143 e->flags &= ~EDGE_FALLTHRU;
1144 if (target == EXIT_BLOCK_PTR)
1147 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1154 rtx label = block_label (target);
1155 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1156 JUMP_LABEL (BB_END (jump_block)) = label;
1157 LABEL_NUSES (label)++;
1160 emit_barrier_after (BB_END (jump_block));
1161 redirect_edge_succ_nodup (e, target);
1163 if (abnormal_edge_flags)
1164 make_edge (src, target, abnormal_edge_flags);
1169 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1170 (and possibly create new basic block) to make edge non-fallthru.
1171 Return newly created BB or NULL if none. */
1174 force_nonfallthru (edge e)
1176 return force_nonfallthru_and_redirect (e, e->dest);
1179 /* Redirect edge even at the expense of creating new jump insn or
1180 basic block. Return new basic block if created, NULL otherwise.
1181 Abort if conversion is impossible. */
1184 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1186 if (redirect_edge_and_branch (e, target)
1187 || e->dest == target)
1190 /* In case the edge redirection failed, try to force it to be non-fallthru
1191 and redirect newly created simplejump. */
1192 return force_nonfallthru_and_redirect (e, target);
1195 /* The given edge should potentially be a fallthru edge. If that is in
1196 fact true, delete the jump and barriers that are in the way. */
1199 rtl_tidy_fallthru_edge (edge e)
1202 basic_block b = e->src, c = b->next_bb;
1206 FOR_EACH_EDGE (e2, ei, b->succs)
1210 /* ??? In a late-running flow pass, other folks may have deleted basic
1211 blocks by nopping out blocks, leaving multiple BARRIERs between here
1212 and the target label. They ought to be chastized and fixed.
1214 We can also wind up with a sequence of undeletable labels between
1215 one block and the next.
1217 So search through a sequence of barriers, labels, and notes for
1218 the head of block C and assert that we really do fall through. */
1220 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1224 /* Remove what will soon cease being the jump insn from the source block.
1225 If block B consisted only of this single jump, turn it into a deleted
1230 && (any_uncondjump_p (q)
1231 || (EDGE_SUCC (b, 0) == e && ei.index == EDGE_COUNT (b->succs) - 1)))
1234 /* If this was a conditional jump, we need to also delete
1235 the insn that set cc0. */
1236 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1242 /* We don't want a block to end on a line-number note since that has
1243 the potential of changing the code between -g and not -g. */
1244 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1248 /* Selectively unlink the sequence. */
1249 if (q != PREV_INSN (BB_HEAD (c)))
1250 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1252 e->flags |= EDGE_FALLTHRU;
1255 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1256 is back edge of syntactic loop. */
1259 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1268 /* ??? Could we guarantee that bb indices are monotone, so that we could
1269 just compare them? */
1270 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1276 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1277 insn = NEXT_INSN (insn))
1280 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1282 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1289 /* Should move basic block BB after basic block AFTER. NIY. */
1292 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1293 basic_block after ATTRIBUTE_UNUSED)
1298 /* Split a (typically critical) edge. Return the new block.
1299 Abort on abnormal edges.
1301 ??? The code generally expects to be called on critical edges.
1302 The case of a block ending in an unconditional jump to a
1303 block with multiple predecessors is not handled optimally. */
1306 rtl_split_edge (edge edge_in)
1311 /* Abnormal edges cannot be split. */
1312 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1314 /* We are going to place the new block in front of edge destination.
1315 Avoid existence of fallthru predecessors. */
1316 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1321 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1322 if (e->flags & EDGE_FALLTHRU)
1326 force_nonfallthru (e);
1329 /* Create the basic block note.
1331 Where we place the note can have a noticeable impact on the generated
1332 code. Consider this cfg:
1342 If we need to insert an insn on the edge from block 0 to block 1,
1343 we want to ensure the instructions we insert are outside of any
1344 loop notes that physically sit between block 0 and block 1. Otherwise
1345 we confuse the loop optimizer into thinking the loop is a phony. */
1347 if (edge_in->dest != EXIT_BLOCK_PTR
1348 && PREV_INSN (BB_HEAD (edge_in->dest))
1349 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1350 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1351 == NOTE_INSN_LOOP_BEG)
1352 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1353 before = PREV_INSN (BB_HEAD (edge_in->dest));
1354 else if (edge_in->dest != EXIT_BLOCK_PTR)
1355 before = BB_HEAD (edge_in->dest);
1359 /* If this is a fall through edge to the exit block, the blocks might be
1360 not adjacent, and the right place is the after the source. */
1361 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1363 before = NEXT_INSN (BB_END (edge_in->src));
1366 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1367 before = NEXT_INSN (before);
1368 bb = create_basic_block (before, NULL, edge_in->src);
1369 BB_COPY_PARTITION (bb, edge_in->src);
1373 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1374 /* ??? Why not edge_in->dest->prev_bb here? */
1375 BB_COPY_PARTITION (bb, edge_in->dest);
1378 /* ??? This info is likely going to be out of date very soon. */
1379 if (edge_in->dest->global_live_at_start)
1381 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (®_obstack);
1382 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (®_obstack);
1383 COPY_REG_SET (bb->global_live_at_start,
1384 edge_in->dest->global_live_at_start);
1385 COPY_REG_SET (bb->global_live_at_end,
1386 edge_in->dest->global_live_at_start);
1389 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1391 /* For non-fallthru edges, we must adjust the predecessor's
1392 jump instruction to target our new block. */
1393 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1395 edge redirected = redirect_edge_and_branch (edge_in, bb);
1396 gcc_assert (redirected);
1399 redirect_edge_succ (edge_in, bb);
1404 /* Queue instructions for insertion on an edge between two basic blocks.
1405 The new instructions and basic blocks (if any) will not appear in the
1406 CFG until commit_edge_insertions is called. */
1409 insert_insn_on_edge (rtx pattern, edge e)
1411 /* We cannot insert instructions on an abnormal critical edge.
1412 It will be easier to find the culprit if we die now. */
1413 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1415 if (e->insns.r == NULL_RTX)
1418 push_to_sequence (e->insns.r);
1420 emit_insn (pattern);
1422 e->insns.r = get_insns ();
1426 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1427 registers that are killed by the store. */
1429 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1431 regset killed = data;
1434 if (GET_CODE (reg) == SUBREG)
1435 reg = SUBREG_REG (reg);
1438 regno = REGNO (reg);
1439 if (regno >= FIRST_PSEUDO_REGISTER)
1440 SET_REGNO_REG_SET (killed, regno);
1443 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1444 SET_REGNO_REG_SET (killed, regno + i);
1448 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1449 it checks whether this will not clobber the registers that are live on the
1450 edge (i.e. it requires liveness information to be up-to-date) and if there
1451 are some, then it tries to save and restore them. Returns true if
1454 safe_insert_insn_on_edge (rtx insn, edge e)
1458 rtx save_regs = NULL_RTX;
1461 enum machine_mode mode;
1462 reg_set_iterator rsi;
1464 #ifdef AVOID_CCMODE_COPIES
1470 killed = OBSTACK_ALLOC_REG_SET (®_obstack);
1472 for (x = insn; x; x = NEXT_INSN (x))
1474 note_stores (PATTERN (x), mark_killed_regs, killed);
1475 bitmap_and_into (killed, e->dest->global_live_at_start);
1477 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno, rsi)
1479 mode = regno < FIRST_PSEUDO_REGISTER
1480 ? reg_raw_mode[regno]
1481 : GET_MODE (regno_reg_rtx[regno]);
1482 if (mode == VOIDmode)
1485 if (noccmode && mode == CCmode)
1488 save_regs = alloc_EXPR_LIST (0,
1491 gen_raw_REG (mode, regno)),
1500 for (x = save_regs; x; x = XEXP (x, 1))
1502 from = XEXP (XEXP (x, 0), 1);
1503 to = XEXP (XEXP (x, 0), 0);
1504 emit_move_insn (to, from);
1507 for (x = save_regs; x; x = XEXP (x, 1))
1509 from = XEXP (XEXP (x, 0), 0);
1510 to = XEXP (XEXP (x, 0), 1);
1511 emit_move_insn (to, from);
1513 insn = get_insns ();
1515 free_EXPR_LIST_list (&save_regs);
1517 insert_insn_on_edge (insn, e);
1519 FREE_REG_SET (killed);
1523 /* Update the CFG for the instructions queued on edge E. */
1526 commit_one_edge_insertion (edge e, int watch_calls)
1528 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1529 basic_block bb = NULL;
1531 /* Pull the insns off the edge now since the edge might go away. */
1533 e->insns.r = NULL_RTX;
1535 /* Special case -- avoid inserting code between call and storing
1536 its return value. */
1537 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1538 && EDGE_COUNT (e->dest->preds) == 1
1539 && e->src != ENTRY_BLOCK_PTR
1540 && CALL_P (BB_END (e->src)))
1542 rtx next = next_nonnote_insn (BB_END (e->src));
1544 after = BB_HEAD (e->dest);
1545 /* The first insn after the call may be a stack pop, skip it. */
1547 && keep_with_call_p (next))
1550 next = next_nonnote_insn (next);
1554 if (!before && !after)
1556 /* Figure out where to put these things. If the destination has
1557 one predecessor, insert there. Except for the exit block. */
1558 if (EDGE_COUNT (e->dest->preds) == 1 && e->dest != EXIT_BLOCK_PTR)
1562 /* Get the location correct wrt a code label, and "nice" wrt
1563 a basic block note, and before everything else. */
1566 tmp = NEXT_INSN (tmp);
1567 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1568 tmp = NEXT_INSN (tmp);
1571 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1572 tmp = NEXT_INSN (tmp);
1573 if (tmp == BB_HEAD (bb))
1576 after = PREV_INSN (tmp);
1578 after = get_last_insn ();
1581 /* If the source has one successor and the edge is not abnormal,
1582 insert there. Except for the entry block. */
1583 else if ((e->flags & EDGE_ABNORMAL) == 0
1584 && EDGE_COUNT (e->src->succs) == 1
1585 && e->src != ENTRY_BLOCK_PTR)
1589 /* It is possible to have a non-simple jump here. Consider a target
1590 where some forms of unconditional jumps clobber a register. This
1591 happens on the fr30 for example.
1593 We know this block has a single successor, so we can just emit
1594 the queued insns before the jump. */
1595 if (JUMP_P (BB_END (bb)))
1596 for (before = BB_END (bb);
1597 NOTE_P (PREV_INSN (before))
1598 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1599 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1603 /* We'd better be fallthru, or we've lost track of
1605 gcc_assert (e->flags & EDGE_FALLTHRU);
1607 after = BB_END (bb);
1610 /* Otherwise we must split the edge. */
1613 bb = split_edge (e);
1614 after = BB_END (bb);
1616 if (flag_reorder_blocks_and_partition
1617 && targetm.have_named_sections
1618 && e->src != ENTRY_BLOCK_PTR
1619 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1620 && !(e->flags & EDGE_CROSSING))
1622 rtx bb_note, new_note, cur_insn;
1625 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1626 cur_insn = NEXT_INSN (cur_insn))
1627 if (NOTE_P (cur_insn)
1628 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1634 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1636 NOTE_BASIC_BLOCK (new_note) = bb;
1637 if (JUMP_P (BB_END (bb))
1638 && !any_condjump_p (BB_END (bb))
1639 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
1640 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1641 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1642 if (after == bb_note)
1648 /* Now that we've found the spot, do the insertion. */
1652 emit_insn_before_noloc (insns, before);
1653 last = prev_nonnote_insn (before);
1656 last = emit_insn_after_noloc (insns, after);
1658 if (returnjump_p (last))
1660 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1661 This is not currently a problem because this only happens
1662 for the (single) epilogue, which already has a fallthru edge
1665 e = EDGE_SUCC (bb, 0);
1666 gcc_assert (e->dest == EXIT_BLOCK_PTR
1667 && EDGE_COUNT (bb->succs) == 1 && (e->flags & EDGE_FALLTHRU));
1669 e->flags &= ~EDGE_FALLTHRU;
1670 emit_barrier_after (last);
1673 delete_insn (before);
1676 gcc_assert (!JUMP_P (last));
1678 /* Mark the basic block for find_sub_basic_blocks. */
1682 /* Update the CFG for all queued instructions. */
1685 commit_edge_insertions (void)
1689 bool changed = false;
1691 #ifdef ENABLE_CHECKING
1692 verify_flow_info ();
1695 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1700 FOR_EACH_EDGE (e, ei, bb->succs)
1704 commit_one_edge_insertion (e, false);
1711 blocks = sbitmap_alloc (last_basic_block);
1712 sbitmap_zero (blocks);
1716 SET_BIT (blocks, bb->index);
1717 /* Check for forgotten bb->aux values before commit_edge_insertions
1719 gcc_assert (bb->aux == &bb->aux);
1722 find_many_sub_basic_blocks (blocks);
1723 sbitmap_free (blocks);
1726 /* Update the CFG for all queued instructions, taking special care of inserting
1727 code on edges between call and storing its return value. */
1730 commit_edge_insertions_watch_calls (void)
1734 bool changed = false;
1736 #ifdef ENABLE_CHECKING
1737 verify_flow_info ();
1740 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1745 FOR_EACH_EDGE (e, ei, bb->succs)
1749 commit_one_edge_insertion (e, true);
1756 blocks = sbitmap_alloc (last_basic_block);
1757 sbitmap_zero (blocks);
1761 SET_BIT (blocks, bb->index);
1762 /* Check for forgotten bb->aux values before commit_edge_insertions
1764 gcc_assert (bb->aux == &bb->aux);
1767 find_many_sub_basic_blocks (blocks);
1768 sbitmap_free (blocks);
1771 /* Print out RTL-specific basic block information (live information
1772 at start and end). */
1775 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1781 s_indent = alloca ((size_t) indent + 1);
1782 memset (s_indent, ' ', (size_t) indent);
1783 s_indent[indent] = '\0';
1785 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1786 dump_regset (bb->global_live_at_start, outf);
1789 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1790 insn = NEXT_INSN (insn))
1791 print_rtl_single (outf, insn);
1793 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1794 dump_regset (bb->global_live_at_end, outf);
1798 /* Like print_rtl, but also print out live information for the start of each
1802 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1807 fprintf (outf, "(nil)\n");
1810 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1811 int max_uid = get_max_uid ();
1812 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1813 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1814 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1818 FOR_EACH_BB_REVERSE (bb)
1822 start[INSN_UID (BB_HEAD (bb))] = bb;
1823 end[INSN_UID (BB_END (bb))] = bb;
1824 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1826 enum bb_state state = IN_MULTIPLE_BB;
1828 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1830 in_bb_p[INSN_UID (x)] = state;
1832 if (x == BB_END (bb))
1837 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1841 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1843 fprintf (outf, ";; Start of basic block %d, registers live:",
1845 dump_regset (bb->global_live_at_start, outf);
1849 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1850 && !NOTE_P (tmp_rtx)
1851 && !BARRIER_P (tmp_rtx))
1852 fprintf (outf, ";; Insn is not within a basic block\n");
1853 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1854 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1856 did_output = print_rtl_single (outf, tmp_rtx);
1858 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1860 fprintf (outf, ";; End of basic block %d, registers live:\n",
1862 dump_regset (bb->global_live_at_end, outf);
1875 if (current_function_epilogue_delay_list != 0)
1877 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1878 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1879 tmp_rtx = XEXP (tmp_rtx, 1))
1880 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1885 update_br_prob_note (basic_block bb)
1888 if (!JUMP_P (BB_END (bb)))
1890 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1891 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1893 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1896 /* Verify the CFG and RTL consistency common for both underlying RTL and
1899 Currently it does following checks:
1901 - test head/end pointers
1902 - overlapping of basic blocks
1903 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1904 - tails of basic blocks (ensure that boundary is necessary)
1905 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1906 and NOTE_INSN_BASIC_BLOCK
1907 - verify that no fall_thru edge crosses hot/cold partition boundaries
1909 In future it can be extended check a lot of other stuff as well
1910 (reachability of basic blocks, life information, etc. etc.). */
1913 rtl_verify_flow_info_1 (void)
1915 const int max_uid = get_max_uid ();
1916 rtx last_head = get_last_insn ();
1917 basic_block *bb_info;
1920 basic_block bb, last_bb_seen;
1922 bb_info = xcalloc (max_uid, sizeof (basic_block));
1924 /* Check bb chain & numbers. */
1925 last_bb_seen = ENTRY_BLOCK_PTR;
1927 FOR_EACH_BB_REVERSE (bb)
1929 rtx head = BB_HEAD (bb);
1930 rtx end = BB_END (bb);
1932 /* Verify the end of the basic block is in the INSN chain. */
1933 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1939 error ("end insn %d for block %d not found in the insn stream",
1940 INSN_UID (end), bb->index);
1944 /* Work backwards from the end to the head of the basic block
1945 to verify the head is in the RTL chain. */
1946 for (; x != NULL_RTX; x = PREV_INSN (x))
1948 /* While walking over the insn chain, verify insns appear
1949 in only one basic block and initialize the BB_INFO array
1950 used by other passes. */
1951 if (bb_info[INSN_UID (x)] != NULL)
1953 error ("insn %d is in multiple basic blocks (%d and %d)",
1954 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1958 bb_info[INSN_UID (x)] = bb;
1965 error ("head insn %d for block %d not found in the insn stream",
1966 INSN_UID (head), bb->index);
1973 /* Now check the basic blocks (boundaries etc.) */
1974 FOR_EACH_BB_REVERSE (bb)
1976 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1977 edge e, fallthru = NULL;
1981 if (INSN_P (BB_END (bb))
1982 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1983 && EDGE_COUNT (bb->succs) >= 2
1984 && any_condjump_p (BB_END (bb)))
1986 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1987 && profile_status != PROFILE_ABSENT)
1989 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1990 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1994 FOR_EACH_EDGE (e, ei, bb->succs)
1996 if (e->flags & EDGE_FALLTHRU)
1998 n_fallthru++, fallthru = e;
1999 if ((e->flags & EDGE_CROSSING)
2000 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
2001 && e->src != ENTRY_BLOCK_PTR
2002 && e->dest != EXIT_BLOCK_PTR))
2004 error ("Fallthru edge crosses section boundary (bb %i)",
2010 if ((e->flags & ~(EDGE_DFS_BACK
2012 | EDGE_IRREDUCIBLE_LOOP
2014 | EDGE_CROSSING)) == 0)
2017 if (e->flags & EDGE_ABNORMAL_CALL)
2020 if (e->flags & EDGE_EH)
2022 else if (e->flags & EDGE_ABNORMAL)
2026 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2027 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2029 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2033 && (!JUMP_P (BB_END (bb))
2034 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2035 || any_condjump_p (BB_END (bb))))))
2037 error ("Too many outgoing branch edges from bb %i", bb->index);
2040 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2042 error ("Fallthru edge after unconditional jump %i", bb->index);
2045 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2047 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2050 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2051 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2053 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2056 if (n_call && !CALL_P (BB_END (bb)))
2058 error ("Call edges for non-call insn in bb %i", bb->index);
2062 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2063 && (!JUMP_P (BB_END (bb))
2064 || any_condjump_p (BB_END (bb))
2065 || any_uncondjump_p (BB_END (bb))))
2067 error ("Abnormal edges for no purpose in bb %i", bb->index);
2071 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2072 /* We may have a barrier inside a basic block before dead code
2073 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2074 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2077 if (! BLOCK_FOR_INSN (x))
2079 ("insn %d inside basic block %d but block_for_insn is NULL",
2080 INSN_UID (x), bb->index);
2083 ("insn %d inside basic block %d but block_for_insn is %i",
2084 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2089 /* OK pointers are correct. Now check the header of basic
2090 block. It ought to contain optional CODE_LABEL followed
2091 by NOTE_BASIC_BLOCK. */
2095 if (BB_END (bb) == x)
2097 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2105 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2107 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2112 if (BB_END (bb) == x)
2113 /* Do checks for empty blocks here. */
2116 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2118 if (NOTE_INSN_BASIC_BLOCK_P (x))
2120 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2121 INSN_UID (x), bb->index);
2125 if (x == BB_END (bb))
2128 if (control_flow_insn_p (x))
2130 error ("in basic block %d:", bb->index);
2131 fatal_insn ("flow control insn inside a basic block", x);
2141 /* Verify the CFG and RTL consistency common for both underlying RTL and
2144 Currently it does following checks:
2145 - all checks of rtl_verify_flow_info_1
2146 - check that all insns are in the basic blocks
2147 (except the switch handling code, barriers and notes)
2148 - check that all returns are followed by barriers
2149 - check that all fallthru edge points to the adjacent blocks. */
2151 rtl_verify_flow_info (void)
2154 int err = rtl_verify_flow_info_1 ();
2157 const rtx rtx_first = get_insns ();
2158 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2160 FOR_EACH_BB_REVERSE (bb)
2165 FOR_EACH_EDGE (e, ei, bb->succs)
2166 if (e->flags & EDGE_FALLTHRU)
2172 /* Ensure existence of barrier in BB with no fallthru edges. */
2173 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2174 insn = NEXT_INSN (insn))
2177 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2179 error ("missing barrier after block %i", bb->index);
2184 else if (e->src != ENTRY_BLOCK_PTR
2185 && e->dest != EXIT_BLOCK_PTR)
2189 if (e->src->next_bb != e->dest)
2192 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2193 e->src->index, e->dest->index);
2197 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2198 insn = NEXT_INSN (insn))
2199 if (BARRIER_P (insn)
2200 #ifndef CASE_DROPS_THROUGH
2203 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2207 error ("verify_flow_info: Incorrect fallthru %i->%i",
2208 e->src->index, e->dest->index);
2209 fatal_insn ("wrong insn in the fallthru edge", insn);
2216 last_bb_seen = ENTRY_BLOCK_PTR;
2218 for (x = rtx_first; x; x = NEXT_INSN (x))
2220 if (NOTE_INSN_BASIC_BLOCK_P (x))
2222 bb = NOTE_BASIC_BLOCK (x);
2225 if (bb != last_bb_seen->next_bb)
2226 internal_error ("basic blocks not laid down consecutively");
2228 curr_bb = last_bb_seen = bb;
2233 switch (GET_CODE (x))
2240 /* An addr_vec is placed outside any basic block. */
2242 && JUMP_P (NEXT_INSN (x))
2243 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2244 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2247 /* But in any case, non-deletable labels can appear anywhere. */
2251 fatal_insn ("insn outside basic block", x);
2256 && returnjump_p (x) && ! condjump_p (x)
2257 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2258 fatal_insn ("return not followed by barrier", x);
2259 if (curr_bb && x == BB_END (curr_bb))
2263 if (num_bb_notes != n_basic_blocks)
2265 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2266 num_bb_notes, n_basic_blocks);
2271 /* Assume that the preceding pass has possibly eliminated jump instructions
2272 or converted the unconditional jumps. Eliminate the edges from CFG.
2273 Return true if any edges are eliminated. */
2276 purge_dead_edges (basic_block bb)
2279 rtx insn = BB_END (bb), note;
2280 bool purged = false;
2284 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2285 if (NONJUMP_INSN_P (insn)
2286 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2290 if (! may_trap_p (PATTERN (insn))
2291 || ((eqnote = find_reg_equal_equiv_note (insn))
2292 && ! may_trap_p (XEXP (eqnote, 0))))
2293 remove_note (insn, note);
2296 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2297 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2299 if (e->flags & EDGE_EH)
2301 if (can_throw_internal (BB_END (bb)))
2307 else if (e->flags & EDGE_ABNORMAL_CALL)
2309 if (CALL_P (BB_END (bb))
2310 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2311 || INTVAL (XEXP (note, 0)) >= 0))
2324 bb->flags |= BB_DIRTY;
2334 /* We do care only about conditional jumps and simplejumps. */
2335 if (!any_condjump_p (insn)
2336 && !returnjump_p (insn)
2337 && !simplejump_p (insn))
2340 /* Branch probability/prediction notes are defined only for
2341 condjumps. We've possibly turned condjump into simplejump. */
2342 if (simplejump_p (insn))
2344 note = find_reg_note (insn, REG_BR_PROB, NULL);
2346 remove_note (insn, note);
2347 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2348 remove_note (insn, note);
2351 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2353 /* Avoid abnormal flags to leak from computed jumps turned
2354 into simplejumps. */
2356 e->flags &= ~EDGE_ABNORMAL;
2358 /* See if this edge is one we should keep. */
2359 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2360 /* A conditional jump can fall through into the next
2361 block, so we should keep the edge. */
2366 else if (e->dest != EXIT_BLOCK_PTR
2367 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2368 /* If the destination block is the target of the jump,
2374 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2375 /* If the destination block is the exit block, and this
2376 instruction is a return, then keep the edge. */
2381 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2382 /* Keep the edges that correspond to exceptions thrown by
2383 this instruction and rematerialize the EDGE_ABNORMAL
2384 flag we just cleared above. */
2386 e->flags |= EDGE_ABNORMAL;
2391 /* We do not need this edge. */
2392 bb->flags |= BB_DIRTY;
2397 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2401 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2406 /* Redistribute probabilities. */
2407 if (EDGE_COUNT (bb->succs) == 1)
2409 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2410 EDGE_SUCC (bb, 0)->count = bb->count;
2414 note = find_reg_note (insn, REG_BR_PROB, NULL);
2418 b = BRANCH_EDGE (bb);
2419 f = FALLTHRU_EDGE (bb);
2420 b->probability = INTVAL (XEXP (note, 0));
2421 f->probability = REG_BR_PROB_BASE - b->probability;
2422 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2423 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2428 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2430 /* First, there should not be any EH or ABCALL edges resulting
2431 from non-local gotos and the like. If there were, we shouldn't
2432 have created the sibcall in the first place. Second, there
2433 should of course never have been a fallthru edge. */
2434 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2435 gcc_assert (EDGE_SUCC (bb, 0)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2440 /* If we don't see a jump insn, we don't know exactly why the block would
2441 have been broken at this point. Look for a simple, non-fallthru edge,
2442 as these are only created by conditional branches. If we find such an
2443 edge we know that there used to be a jump here and can then safely
2444 remove all non-fallthru edges. */
2446 FOR_EACH_EDGE (e, ei, bb->succs)
2447 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2456 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2458 if (!(e->flags & EDGE_FALLTHRU))
2460 bb->flags |= BB_DIRTY;
2468 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2470 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2471 EDGE_SUCC (bb, 0)->count = bb->count;
2474 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2479 /* Search all basic blocks for potentially dead edges and purge them. Return
2480 true if some edge has been eliminated. */
2483 purge_all_dead_edges (int update_life_p)
2491 blocks = sbitmap_alloc (last_basic_block);
2492 sbitmap_zero (blocks);
2497 bool purged_here = purge_dead_edges (bb);
2499 purged |= purged_here;
2500 if (purged_here && update_life_p)
2501 SET_BIT (blocks, bb->index);
2504 if (update_life_p && purged)
2505 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2506 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2507 | PROP_KILL_DEAD_CODE);
2510 sbitmap_free (blocks);
2514 /* Same as split_block but update cfg_layout structures. */
2517 cfg_layout_split_block (basic_block bb, void *insnp)
2520 basic_block new_bb = rtl_split_block (bb, insn);
2522 new_bb->rbi->footer = bb->rbi->footer;
2523 bb->rbi->footer = NULL;
2529 /* Redirect Edge to DEST. */
2531 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2533 basic_block src = e->src;
2536 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2539 if (e->dest == dest)
2542 if (e->src != ENTRY_BLOCK_PTR
2543 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2545 src->flags |= BB_DIRTY;
2549 if (e->src == ENTRY_BLOCK_PTR
2550 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2553 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2554 e->src->index, dest->index);
2556 e->src->flags |= BB_DIRTY;
2557 redirect_edge_succ (e, dest);
2561 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2562 in the case the basic block appears to be in sequence. Avoid this
2565 if (e->flags & EDGE_FALLTHRU)
2567 /* Redirect any branch edges unified with the fallthru one. */
2568 if (JUMP_P (BB_END (src))
2569 && label_is_jump_target_p (BB_HEAD (e->dest),
2575 fprintf (dump_file, "Fallthru edge unified with branch "
2576 "%i->%i redirected to %i\n",
2577 e->src->index, e->dest->index, dest->index);
2578 e->flags &= ~EDGE_FALLTHRU;
2579 redirected = redirect_branch_edge (e, dest);
2580 gcc_assert (redirected);
2581 e->flags |= EDGE_FALLTHRU;
2582 e->src->flags |= BB_DIRTY;
2585 /* In case we are redirecting fallthru edge to the branch edge
2586 of conditional jump, remove it. */
2587 if (EDGE_COUNT (src->succs) == 2)
2594 FOR_EACH_EDGE (tmp, ei, src->succs)
2604 if (EDGE_COUNT (src->succs) > (ix + 1))
2605 s = EDGE_SUCC (src, ix + 1);
2607 s = EDGE_SUCC (src, 0);
2610 && any_condjump_p (BB_END (src))
2611 && onlyjump_p (BB_END (src)))
2612 delete_insn (BB_END (src));
2614 ret = redirect_edge_succ_nodup (e, dest);
2616 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2617 e->src->index, e->dest->index, dest->index);
2620 ret = redirect_branch_edge (e, dest);
2622 /* We don't want simplejumps in the insn stream during cfglayout. */
2623 gcc_assert (!simplejump_p (BB_END (src)));
2625 src->flags |= BB_DIRTY;
2629 /* Simple wrapper as we always can redirect fallthru edges. */
2631 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2633 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2635 gcc_assert (redirected);
2639 /* Same as delete_basic_block but update cfg_layout structures. */
2642 cfg_layout_delete_block (basic_block bb)
2644 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2646 if (bb->rbi->header)
2648 next = BB_HEAD (bb);
2650 NEXT_INSN (prev) = bb->rbi->header;
2652 set_first_insn (bb->rbi->header);
2653 PREV_INSN (bb->rbi->header) = prev;
2654 insn = bb->rbi->header;
2655 while (NEXT_INSN (insn))
2656 insn = NEXT_INSN (insn);
2657 NEXT_INSN (insn) = next;
2658 PREV_INSN (next) = insn;
2660 next = NEXT_INSN (BB_END (bb));
2661 if (bb->rbi->footer)
2663 insn = bb->rbi->footer;
2666 if (BARRIER_P (insn))
2668 if (PREV_INSN (insn))
2669 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2671 bb->rbi->footer = NEXT_INSN (insn);
2672 if (NEXT_INSN (insn))
2673 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2677 insn = NEXT_INSN (insn);
2679 if (bb->rbi->footer)
2682 NEXT_INSN (insn) = bb->rbi->footer;
2683 PREV_INSN (bb->rbi->footer) = insn;
2684 while (NEXT_INSN (insn))
2685 insn = NEXT_INSN (insn);
2686 NEXT_INSN (insn) = next;
2688 PREV_INSN (next) = insn;
2690 set_last_insn (insn);
2693 if (bb->next_bb != EXIT_BLOCK_PTR)
2694 to = &bb->next_bb->rbi->header;
2696 to = &cfg_layout_function_footer;
2697 rtl_delete_block (bb);
2700 prev = NEXT_INSN (prev);
2702 prev = get_insns ();
2704 next = PREV_INSN (next);
2706 next = get_last_insn ();
2708 if (next && NEXT_INSN (next) != prev)
2710 remaints = unlink_insn_chain (prev, next);
2712 while (NEXT_INSN (insn))
2713 insn = NEXT_INSN (insn);
2714 NEXT_INSN (insn) = *to;
2716 PREV_INSN (*to) = insn;
2721 /* Return true when blocks A and B can be safely merged. */
2723 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2725 /* If we are partitioning hot/cold basic blocks, we don't want to
2726 mess up unconditional or indirect jumps that cross between hot
2729 Basic block partitioning may result in some jumps that appear to
2730 be optimizable (or blocks that appear to be mergeable), but which really
2731 must be left untouched (they are required to make it safely across
2732 partition boundaries). See the comments at the top of
2733 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2735 if (flag_reorder_blocks_and_partition
2736 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2737 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2738 || BB_PARTITION (a) != BB_PARTITION (b)))
2741 /* There must be exactly one edge in between the blocks. */
2742 return (EDGE_COUNT (a->succs) == 1
2743 && EDGE_SUCC (a, 0)->dest == b
2744 && EDGE_COUNT (b->preds) == 1
2746 /* Must be simple edge. */
2747 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
2748 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2749 /* If the jump insn has side effects,
2750 we can't kill the edge. */
2751 && (!JUMP_P (BB_END (a))
2752 || (reload_completed
2753 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2756 /* Merge block A and B, abort when it is not possible. */
2758 cfg_layout_merge_blocks (basic_block a, basic_block b)
2760 #ifdef ENABLE_CHECKING
2761 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2764 /* If there was a CODE_LABEL beginning B, delete it. */
2765 if (LABEL_P (BB_HEAD (b)))
2766 delete_insn (BB_HEAD (b));
2768 /* We should have fallthru edge in a, or we can do dummy redirection to get
2770 if (JUMP_P (BB_END (a)))
2771 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2772 gcc_assert (!JUMP_P (BB_END (a)));
2774 /* Possible line number notes should appear in between. */
2777 rtx first = BB_END (a), last;
2779 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2780 delete_insn_chain (NEXT_INSN (first), last);
2781 b->rbi->header = NULL;
2784 /* In the case basic blocks are not adjacent, move them around. */
2785 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2787 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2789 emit_insn_after_noloc (first, BB_END (a));
2790 /* Skip possible DELETED_LABEL insn. */
2791 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2792 first = NEXT_INSN (first);
2793 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2795 delete_insn (first);
2797 /* Otherwise just re-associate the instructions. */
2802 for (insn = BB_HEAD (b);
2803 insn != NEXT_INSN (BB_END (b));
2804 insn = NEXT_INSN (insn))
2805 set_block_for_insn (insn, a);
2807 /* Skip possible DELETED_LABEL insn. */
2808 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2809 insn = NEXT_INSN (insn);
2810 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2812 BB_END (a) = BB_END (b);
2816 /* Possible tablejumps and barriers should appear after the block. */
2819 if (!a->rbi->footer)
2820 a->rbi->footer = b->rbi->footer;
2823 rtx last = a->rbi->footer;
2825 while (NEXT_INSN (last))
2826 last = NEXT_INSN (last);
2827 NEXT_INSN (last) = b->rbi->footer;
2828 PREV_INSN (b->rbi->footer) = last;
2830 b->rbi->footer = NULL;
2834 fprintf (dump_file, "Merged blocks %d and %d.\n",
2835 a->index, b->index);
2841 cfg_layout_split_edge (edge e)
2844 basic_block new_bb =
2845 create_basic_block (e->src != ENTRY_BLOCK_PTR
2846 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2849 /* ??? This info is likely going to be out of date very soon, but we must
2850 create it to avoid getting an ICE later. */
2851 if (e->dest->global_live_at_start)
2853 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (®_obstack);
2854 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (®_obstack);
2855 COPY_REG_SET (new_bb->global_live_at_start,
2856 e->dest->global_live_at_start);
2857 COPY_REG_SET (new_bb->global_live_at_end,
2858 e->dest->global_live_at_start);
2861 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2862 redirect_edge_and_branch_force (e, new_bb);
2867 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2870 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2874 /* Return 1 if BB ends with a call, possibly followed by some
2875 instructions that must stay with the call, 0 otherwise. */
2878 rtl_block_ends_with_call_p (basic_block bb)
2880 rtx insn = BB_END (bb);
2882 while (!CALL_P (insn)
2883 && insn != BB_HEAD (bb)
2884 && keep_with_call_p (insn))
2885 insn = PREV_INSN (insn);
2886 return (CALL_P (insn));
2889 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2892 rtl_block_ends_with_condjump_p (basic_block bb)
2894 return any_condjump_p (BB_END (bb));
2897 /* Return true if we need to add fake edge to exit.
2898 Helper function for rtl_flow_call_edges_add. */
2901 need_fake_edge_p (rtx insn)
2907 && !SIBLING_CALL_P (insn)
2908 && !find_reg_note (insn, REG_NORETURN, NULL)
2909 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2910 && !CONST_OR_PURE_CALL_P (insn)))
2913 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2914 && MEM_VOLATILE_P (PATTERN (insn)))
2915 || (GET_CODE (PATTERN (insn)) == PARALLEL
2916 && asm_noperands (insn) != -1
2917 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2918 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2921 /* Add fake edges to the function exit for any non constant and non noreturn
2922 calls, volatile inline assembly in the bitmap of blocks specified by
2923 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2926 The goal is to expose cases in which entering a basic block does not imply
2927 that all subsequent instructions must be executed. */
2930 rtl_flow_call_edges_add (sbitmap blocks)
2933 int blocks_split = 0;
2934 int last_bb = last_basic_block;
2935 bool check_last_block = false;
2937 if (n_basic_blocks == 0)
2941 check_last_block = true;
2943 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2945 /* In the last basic block, before epilogue generation, there will be
2946 a fallthru edge to EXIT. Special care is required if the last insn
2947 of the last basic block is a call because make_edge folds duplicate
2948 edges, which would result in the fallthru edge also being marked
2949 fake, which would result in the fallthru edge being removed by
2950 remove_fake_edges, which would result in an invalid CFG.
2952 Moreover, we can't elide the outgoing fake edge, since the block
2953 profiler needs to take this into account in order to solve the minimal
2954 spanning tree in the case that the call doesn't return.
2956 Handle this by adding a dummy instruction in a new last basic block. */
2957 if (check_last_block)
2959 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2960 rtx insn = BB_END (bb);
2962 /* Back up past insns that must be kept in the same block as a call. */
2963 while (insn != BB_HEAD (bb)
2964 && keep_with_call_p (insn))
2965 insn = PREV_INSN (insn);
2967 if (need_fake_edge_p (insn))
2971 e = find_edge (bb, EXIT_BLOCK_PTR);
2974 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2975 commit_edge_insertions ();
2980 /* Now add fake edges to the function exit for any non constant
2981 calls since there is no way that we can determine if they will
2984 for (i = 0; i < last_bb; i++)
2986 basic_block bb = BASIC_BLOCK (i);
2993 if (blocks && !TEST_BIT (blocks, i))
2996 for (insn = BB_END (bb); ; insn = prev_insn)
2998 prev_insn = PREV_INSN (insn);
2999 if (need_fake_edge_p (insn))
3002 rtx split_at_insn = insn;
3004 /* Don't split the block between a call and an insn that should
3005 remain in the same block as the call. */
3007 while (split_at_insn != BB_END (bb)
3008 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3009 split_at_insn = NEXT_INSN (split_at_insn);
3011 /* The handling above of the final block before the epilogue
3012 should be enough to verify that there is no edge to the exit
3013 block in CFG already. Calling make_edge in such case would
3014 cause us to mark that edge as fake and remove it later. */
3016 #ifdef ENABLE_CHECKING
3017 if (split_at_insn == BB_END (bb))
3019 e = find_edge (bb, EXIT_BLOCK_PTR);
3020 gcc_assert (e == NULL);
3024 /* Note that the following may create a new basic block
3025 and renumber the existing basic blocks. */
3026 if (split_at_insn != BB_END (bb))
3028 e = split_block (bb, split_at_insn);
3033 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3036 if (insn == BB_HEAD (bb))
3042 verify_flow_info ();
3044 return blocks_split;
3047 /* Implementation of CFG manipulation for linearized RTL. */
3048 struct cfg_hooks rtl_cfg_hooks = {
3050 rtl_verify_flow_info,
3052 rtl_create_basic_block,
3053 rtl_redirect_edge_and_branch,
3054 rtl_redirect_edge_and_branch_force,
3057 rtl_move_block_after,
3058 rtl_can_merge_blocks, /* can_merge_blocks_p */
3062 NULL, /* can_duplicate_block_p */
3063 NULL, /* duplicate_block */
3065 rtl_make_forwarder_block,
3066 rtl_tidy_fallthru_edge,
3067 rtl_block_ends_with_call_p,
3068 rtl_block_ends_with_condjump_p,
3069 rtl_flow_call_edges_add,
3070 NULL, /* execute_on_growing_pred */
3071 NULL /* execute_on_shrinking_pred */
3074 /* Implementation of CFG manipulation for cfg layout RTL, where
3075 basic block connected via fallthru edges does not have to be adjacent.
3076 This representation will hopefully become the default one in future
3077 version of the compiler. */
3079 /* We do not want to declare these functions in a header file, since they
3080 should only be used through the cfghooks interface, and we do not want to
3081 move them here since it would require also moving quite a lot of related
3083 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3084 extern basic_block cfg_layout_duplicate_bb (basic_block);
3086 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3088 rtl_verify_flow_info_1,
3090 cfg_layout_create_basic_block,
3091 cfg_layout_redirect_edge_and_branch,
3092 cfg_layout_redirect_edge_and_branch_force,
3093 cfg_layout_delete_block,
3094 cfg_layout_split_block,
3095 rtl_move_block_after,
3096 cfg_layout_can_merge_blocks_p,
3097 cfg_layout_merge_blocks,
3100 cfg_layout_can_duplicate_bb_p,
3101 cfg_layout_duplicate_bb,
3102 cfg_layout_split_edge,
3103 rtl_make_forwarder_block,
3105 rtl_block_ends_with_call_p,
3106 rtl_block_ends_with_condjump_p,
3107 rtl_flow_call_edges_add,
3108 NULL, /* execute_on_growing_pred */
3109 NULL /* execute_on_shrinking_pred */