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 = ALLOC_REG_SET (®_obstack);
488 new_bb->global_live_at_end = 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 = ALLOC_REG_SET (®_obstack);
1093 jump_block->global_live_at_end = ALLOC_REG_SET (®_obstack);
1094 COPY_REG_SET (jump_block->global_live_at_start,
1095 target->global_live_at_start);
1096 COPY_REG_SET (jump_block->global_live_at_end,
1097 target->global_live_at_start);
1100 /* Make sure new block ends up in correct hot/cold section. */
1102 BB_COPY_PARTITION (jump_block, e->src);
1103 if (flag_reorder_blocks_and_partition
1104 && targetm.have_named_sections)
1106 if (BB_PARTITION (jump_block) == BB_COLD_PARTITION)
1108 rtx bb_note, new_note;
1109 for (bb_note = BB_HEAD (jump_block);
1110 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1111 bb_note = NEXT_INSN (bb_note))
1112 if (NOTE_P (bb_note)
1113 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1115 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1117 NOTE_BASIC_BLOCK (new_note) = jump_block;
1119 if (JUMP_P (BB_END (jump_block))
1120 && !any_condjump_p (BB_END (jump_block))
1121 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1122 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1123 (REG_CROSSING_JUMP, NULL_RTX,
1124 REG_NOTES (BB_END (jump_block)));
1128 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1129 new_edge->probability = e->probability;
1130 new_edge->count = e->count;
1132 /* Redirect old edge. */
1133 redirect_edge_pred (e, jump_block);
1134 e->probability = REG_BR_PROB_BASE;
1136 new_bb = jump_block;
1139 jump_block = e->src;
1141 e->flags &= ~EDGE_FALLTHRU;
1142 if (target == EXIT_BLOCK_PTR)
1145 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1152 rtx label = block_label (target);
1153 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1154 JUMP_LABEL (BB_END (jump_block)) = label;
1155 LABEL_NUSES (label)++;
1158 emit_barrier_after (BB_END (jump_block));
1159 redirect_edge_succ_nodup (e, target);
1161 if (abnormal_edge_flags)
1162 make_edge (src, target, abnormal_edge_flags);
1167 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1168 (and possibly create new basic block) to make edge non-fallthru.
1169 Return newly created BB or NULL if none. */
1172 force_nonfallthru (edge e)
1174 return force_nonfallthru_and_redirect (e, e->dest);
1177 /* Redirect edge even at the expense of creating new jump insn or
1178 basic block. Return new basic block if created, NULL otherwise.
1179 Abort if conversion is impossible. */
1182 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1184 if (redirect_edge_and_branch (e, target)
1185 || e->dest == target)
1188 /* In case the edge redirection failed, try to force it to be non-fallthru
1189 and redirect newly created simplejump. */
1190 return force_nonfallthru_and_redirect (e, target);
1193 /* The given edge should potentially be a fallthru edge. If that is in
1194 fact true, delete the jump and barriers that are in the way. */
1197 rtl_tidy_fallthru_edge (edge e)
1200 basic_block b = e->src, c = b->next_bb;
1204 FOR_EACH_EDGE (e2, ei, b->succs)
1208 /* ??? In a late-running flow pass, other folks may have deleted basic
1209 blocks by nopping out blocks, leaving multiple BARRIERs between here
1210 and the target label. They ought to be chastized and fixed.
1212 We can also wind up with a sequence of undeletable labels between
1213 one block and the next.
1215 So search through a sequence of barriers, labels, and notes for
1216 the head of block C and assert that we really do fall through. */
1218 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1222 /* Remove what will soon cease being the jump insn from the source block.
1223 If block B consisted only of this single jump, turn it into a deleted
1228 && (any_uncondjump_p (q)
1229 || (EDGE_SUCC (b, 0) == e && ei.index == EDGE_COUNT (b->succs) - 1)))
1232 /* If this was a conditional jump, we need to also delete
1233 the insn that set cc0. */
1234 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1240 /* We don't want a block to end on a line-number note since that has
1241 the potential of changing the code between -g and not -g. */
1242 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1246 /* Selectively unlink the sequence. */
1247 if (q != PREV_INSN (BB_HEAD (c)))
1248 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1250 e->flags |= EDGE_FALLTHRU;
1253 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1254 is back edge of syntactic loop. */
1257 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1266 /* ??? Could we guarantee that bb indices are monotone, so that we could
1267 just compare them? */
1268 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1274 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1275 insn = NEXT_INSN (insn))
1278 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1280 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1287 /* Should move basic block BB after basic block AFTER. NIY. */
1290 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1291 basic_block after ATTRIBUTE_UNUSED)
1296 /* Split a (typically critical) edge. Return the new block.
1297 Abort on abnormal edges.
1299 ??? The code generally expects to be called on critical edges.
1300 The case of a block ending in an unconditional jump to a
1301 block with multiple predecessors is not handled optimally. */
1304 rtl_split_edge (edge edge_in)
1309 /* Abnormal edges cannot be split. */
1310 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1312 /* We are going to place the new block in front of edge destination.
1313 Avoid existence of fallthru predecessors. */
1314 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1319 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1320 if (e->flags & EDGE_FALLTHRU)
1324 force_nonfallthru (e);
1327 /* Create the basic block note.
1329 Where we place the note can have a noticeable impact on the generated
1330 code. Consider this cfg:
1340 If we need to insert an insn on the edge from block 0 to block 1,
1341 we want to ensure the instructions we insert are outside of any
1342 loop notes that physically sit between block 0 and block 1. Otherwise
1343 we confuse the loop optimizer into thinking the loop is a phony. */
1345 if (edge_in->dest != EXIT_BLOCK_PTR
1346 && PREV_INSN (BB_HEAD (edge_in->dest))
1347 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1348 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1349 == NOTE_INSN_LOOP_BEG)
1350 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1351 before = PREV_INSN (BB_HEAD (edge_in->dest));
1352 else if (edge_in->dest != EXIT_BLOCK_PTR)
1353 before = BB_HEAD (edge_in->dest);
1357 /* If this is a fall through edge to the exit block, the blocks might be
1358 not adjacent, and the right place is the after the source. */
1359 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1361 before = NEXT_INSN (BB_END (edge_in->src));
1364 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1365 before = NEXT_INSN (before);
1366 bb = create_basic_block (before, NULL, edge_in->src);
1367 BB_COPY_PARTITION (bb, edge_in->src);
1371 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1372 /* ??? Why not edge_in->dest->prev_bb here? */
1373 BB_COPY_PARTITION (bb, edge_in->dest);
1376 /* ??? This info is likely going to be out of date very soon. */
1377 if (edge_in->dest->global_live_at_start)
1379 bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
1380 bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
1381 COPY_REG_SET (bb->global_live_at_start,
1382 edge_in->dest->global_live_at_start);
1383 COPY_REG_SET (bb->global_live_at_end,
1384 edge_in->dest->global_live_at_start);
1387 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1389 /* For non-fallthru edges, we must adjust the predecessor's
1390 jump instruction to target our new block. */
1391 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1393 edge redirected = redirect_edge_and_branch (edge_in, bb);
1394 gcc_assert (redirected);
1397 redirect_edge_succ (edge_in, bb);
1402 /* Queue instructions for insertion on an edge between two basic blocks.
1403 The new instructions and basic blocks (if any) will not appear in the
1404 CFG until commit_edge_insertions is called. */
1407 insert_insn_on_edge (rtx pattern, edge e)
1409 /* We cannot insert instructions on an abnormal critical edge.
1410 It will be easier to find the culprit if we die now. */
1411 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1413 if (e->insns.r == NULL_RTX)
1416 push_to_sequence (e->insns.r);
1418 emit_insn (pattern);
1420 e->insns.r = get_insns ();
1424 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1425 registers that are killed by the store. */
1427 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1429 regset killed = data;
1432 if (GET_CODE (reg) == SUBREG)
1433 reg = SUBREG_REG (reg);
1436 regno = REGNO (reg);
1437 if (regno >= FIRST_PSEUDO_REGISTER)
1438 SET_REGNO_REG_SET (killed, regno);
1441 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1442 SET_REGNO_REG_SET (killed, regno + i);
1446 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1447 it checks whether this will not clobber the registers that are live on the
1448 edge (i.e. it requires liveness information to be up-to-date) and if there
1449 are some, then it tries to save and restore them. Returns true if
1452 safe_insert_insn_on_edge (rtx insn, edge e)
1456 rtx save_regs = NULL_RTX;
1459 enum machine_mode mode;
1460 reg_set_iterator rsi;
1462 #ifdef AVOID_CCMODE_COPIES
1468 killed = ALLOC_REG_SET (®_obstack);
1470 for (x = insn; x; x = NEXT_INSN (x))
1472 note_stores (PATTERN (x), mark_killed_regs, killed);
1473 bitmap_and_into (killed, e->dest->global_live_at_start);
1475 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno, rsi)
1477 mode = regno < FIRST_PSEUDO_REGISTER
1478 ? reg_raw_mode[regno]
1479 : GET_MODE (regno_reg_rtx[regno]);
1480 if (mode == VOIDmode)
1483 if (noccmode && mode == CCmode)
1486 save_regs = alloc_EXPR_LIST (0,
1489 gen_raw_REG (mode, regno)),
1498 for (x = save_regs; x; x = XEXP (x, 1))
1500 from = XEXP (XEXP (x, 0), 1);
1501 to = XEXP (XEXP (x, 0), 0);
1502 emit_move_insn (to, from);
1505 for (x = save_regs; x; x = XEXP (x, 1))
1507 from = XEXP (XEXP (x, 0), 0);
1508 to = XEXP (XEXP (x, 0), 1);
1509 emit_move_insn (to, from);
1511 insn = get_insns ();
1513 free_EXPR_LIST_list (&save_regs);
1515 insert_insn_on_edge (insn, e);
1517 FREE_REG_SET (killed);
1521 /* Update the CFG for the instructions queued on edge E. */
1524 commit_one_edge_insertion (edge e, int watch_calls)
1526 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1527 basic_block bb = NULL;
1529 /* Pull the insns off the edge now since the edge might go away. */
1531 e->insns.r = NULL_RTX;
1533 /* Special case -- avoid inserting code between call and storing
1534 its return value. */
1535 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1536 && EDGE_COUNT (e->dest->preds) == 1
1537 && e->src != ENTRY_BLOCK_PTR
1538 && CALL_P (BB_END (e->src)))
1540 rtx next = next_nonnote_insn (BB_END (e->src));
1542 after = BB_HEAD (e->dest);
1543 /* The first insn after the call may be a stack pop, skip it. */
1545 && keep_with_call_p (next))
1548 next = next_nonnote_insn (next);
1552 if (!before && !after)
1554 /* Figure out where to put these things. If the destination has
1555 one predecessor, insert there. Except for the exit block. */
1556 if (EDGE_COUNT (e->dest->preds) == 1 && e->dest != EXIT_BLOCK_PTR)
1560 /* Get the location correct wrt a code label, and "nice" wrt
1561 a basic block note, and before everything else. */
1564 tmp = NEXT_INSN (tmp);
1565 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1566 tmp = NEXT_INSN (tmp);
1569 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1570 tmp = NEXT_INSN (tmp);
1571 if (tmp == BB_HEAD (bb))
1574 after = PREV_INSN (tmp);
1576 after = get_last_insn ();
1579 /* If the source has one successor and the edge is not abnormal,
1580 insert there. Except for the entry block. */
1581 else if ((e->flags & EDGE_ABNORMAL) == 0
1582 && EDGE_COUNT (e->src->succs) == 1
1583 && e->src != ENTRY_BLOCK_PTR)
1587 /* It is possible to have a non-simple jump here. Consider a target
1588 where some forms of unconditional jumps clobber a register. This
1589 happens on the fr30 for example.
1591 We know this block has a single successor, so we can just emit
1592 the queued insns before the jump. */
1593 if (JUMP_P (BB_END (bb)))
1594 for (before = BB_END (bb);
1595 NOTE_P (PREV_INSN (before))
1596 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1597 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1601 /* We'd better be fallthru, or we've lost track of
1603 gcc_assert (e->flags & EDGE_FALLTHRU);
1605 after = BB_END (bb);
1608 /* Otherwise we must split the edge. */
1611 bb = split_edge (e);
1612 after = BB_END (bb);
1614 if (flag_reorder_blocks_and_partition
1615 && targetm.have_named_sections
1616 && e->src != ENTRY_BLOCK_PTR
1617 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1618 && !(e->flags & EDGE_CROSSING))
1620 rtx bb_note, new_note, cur_insn;
1623 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1624 cur_insn = NEXT_INSN (cur_insn))
1625 if (NOTE_P (cur_insn)
1626 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1632 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1634 NOTE_BASIC_BLOCK (new_note) = bb;
1635 if (JUMP_P (BB_END (bb))
1636 && !any_condjump_p (BB_END (bb))
1637 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
1638 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1639 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1640 if (after == bb_note)
1646 /* Now that we've found the spot, do the insertion. */
1650 emit_insn_before_noloc (insns, before);
1651 last = prev_nonnote_insn (before);
1654 last = emit_insn_after_noloc (insns, after);
1656 if (returnjump_p (last))
1658 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1659 This is not currently a problem because this only happens
1660 for the (single) epilogue, which already has a fallthru edge
1663 e = EDGE_SUCC (bb, 0);
1664 gcc_assert (e->dest == EXIT_BLOCK_PTR
1665 && EDGE_COUNT (bb->succs) == 1 && (e->flags & EDGE_FALLTHRU));
1667 e->flags &= ~EDGE_FALLTHRU;
1668 emit_barrier_after (last);
1671 delete_insn (before);
1674 gcc_assert (!JUMP_P (last));
1676 /* Mark the basic block for find_sub_basic_blocks. */
1680 /* Update the CFG for all queued instructions. */
1683 commit_edge_insertions (void)
1687 bool changed = false;
1689 #ifdef ENABLE_CHECKING
1690 verify_flow_info ();
1693 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1698 FOR_EACH_EDGE (e, ei, bb->succs)
1702 commit_one_edge_insertion (e, false);
1709 blocks = sbitmap_alloc (last_basic_block);
1710 sbitmap_zero (blocks);
1714 SET_BIT (blocks, bb->index);
1715 /* Check for forgotten bb->aux values before commit_edge_insertions
1717 gcc_assert (bb->aux == &bb->aux);
1720 find_many_sub_basic_blocks (blocks);
1721 sbitmap_free (blocks);
1724 /* Update the CFG for all queued instructions, taking special care of inserting
1725 code on edges between call and storing its return value. */
1728 commit_edge_insertions_watch_calls (void)
1732 bool changed = false;
1734 #ifdef ENABLE_CHECKING
1735 verify_flow_info ();
1738 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1743 FOR_EACH_EDGE (e, ei, bb->succs)
1747 commit_one_edge_insertion (e, true);
1754 blocks = sbitmap_alloc (last_basic_block);
1755 sbitmap_zero (blocks);
1759 SET_BIT (blocks, bb->index);
1760 /* Check for forgotten bb->aux values before commit_edge_insertions
1762 gcc_assert (bb->aux == &bb->aux);
1765 find_many_sub_basic_blocks (blocks);
1766 sbitmap_free (blocks);
1769 /* Print out RTL-specific basic block information (live information
1770 at start and end). */
1773 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1779 s_indent = alloca ((size_t) indent + 1);
1780 memset (s_indent, ' ', (size_t) indent);
1781 s_indent[indent] = '\0';
1783 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1784 dump_regset (bb->global_live_at_start, outf);
1787 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1788 insn = NEXT_INSN (insn))
1789 print_rtl_single (outf, insn);
1791 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1792 dump_regset (bb->global_live_at_end, outf);
1796 /* Like print_rtl, but also print out live information for the start of each
1800 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1805 fprintf (outf, "(nil)\n");
1808 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1809 int max_uid = get_max_uid ();
1810 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1811 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1812 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1816 FOR_EACH_BB_REVERSE (bb)
1820 start[INSN_UID (BB_HEAD (bb))] = bb;
1821 end[INSN_UID (BB_END (bb))] = bb;
1822 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1824 enum bb_state state = IN_MULTIPLE_BB;
1826 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1828 in_bb_p[INSN_UID (x)] = state;
1830 if (x == BB_END (bb))
1835 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1839 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1841 fprintf (outf, ";; Start of basic block %d, registers live:",
1843 dump_regset (bb->global_live_at_start, outf);
1847 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1848 && !NOTE_P (tmp_rtx)
1849 && !BARRIER_P (tmp_rtx))
1850 fprintf (outf, ";; Insn is not within a basic block\n");
1851 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1852 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1854 did_output = print_rtl_single (outf, tmp_rtx);
1856 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1858 fprintf (outf, ";; End of basic block %d, registers live:\n",
1860 dump_regset (bb->global_live_at_end, outf);
1873 if (current_function_epilogue_delay_list != 0)
1875 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1876 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1877 tmp_rtx = XEXP (tmp_rtx, 1))
1878 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1883 update_br_prob_note (basic_block bb)
1886 if (!JUMP_P (BB_END (bb)))
1888 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1889 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1891 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1894 /* Verify the CFG and RTL consistency common for both underlying RTL and
1897 Currently it does following checks:
1899 - test head/end pointers
1900 - overlapping of basic blocks
1901 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1902 - tails of basic blocks (ensure that boundary is necessary)
1903 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1904 and NOTE_INSN_BASIC_BLOCK
1905 - verify that no fall_thru edge crosses hot/cold partition boundaries
1907 In future it can be extended check a lot of other stuff as well
1908 (reachability of basic blocks, life information, etc. etc.). */
1911 rtl_verify_flow_info_1 (void)
1913 const int max_uid = get_max_uid ();
1914 rtx last_head = get_last_insn ();
1915 basic_block *bb_info;
1918 basic_block bb, last_bb_seen;
1920 bb_info = xcalloc (max_uid, sizeof (basic_block));
1922 /* Check bb chain & numbers. */
1923 last_bb_seen = ENTRY_BLOCK_PTR;
1925 FOR_EACH_BB_REVERSE (bb)
1927 rtx head = BB_HEAD (bb);
1928 rtx end = BB_END (bb);
1930 /* Verify the end of the basic block is in the INSN chain. */
1931 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1937 error ("end insn %d for block %d not found in the insn stream",
1938 INSN_UID (end), bb->index);
1942 /* Work backwards from the end to the head of the basic block
1943 to verify the head is in the RTL chain. */
1944 for (; x != NULL_RTX; x = PREV_INSN (x))
1946 /* While walking over the insn chain, verify insns appear
1947 in only one basic block and initialize the BB_INFO array
1948 used by other passes. */
1949 if (bb_info[INSN_UID (x)] != NULL)
1951 error ("insn %d is in multiple basic blocks (%d and %d)",
1952 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1956 bb_info[INSN_UID (x)] = bb;
1963 error ("head insn %d for block %d not found in the insn stream",
1964 INSN_UID (head), bb->index);
1971 /* Now check the basic blocks (boundaries etc.) */
1972 FOR_EACH_BB_REVERSE (bb)
1974 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1975 edge e, fallthru = NULL;
1979 if (INSN_P (BB_END (bb))
1980 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1981 && EDGE_COUNT (bb->succs) >= 2
1982 && any_condjump_p (BB_END (bb)))
1984 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1985 && profile_status != PROFILE_ABSENT)
1987 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1988 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1992 FOR_EACH_EDGE (e, ei, bb->succs)
1994 if (e->flags & EDGE_FALLTHRU)
1996 n_fallthru++, fallthru = e;
1997 if ((e->flags & EDGE_CROSSING)
1998 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
1999 && e->src != ENTRY_BLOCK_PTR
2000 && e->dest != EXIT_BLOCK_PTR))
2002 error ("Fallthru edge crosses section boundary (bb %i)",
2008 if ((e->flags & ~(EDGE_DFS_BACK
2010 | EDGE_IRREDUCIBLE_LOOP
2012 | EDGE_CROSSING)) == 0)
2015 if (e->flags & EDGE_ABNORMAL_CALL)
2018 if (e->flags & EDGE_EH)
2020 else if (e->flags & EDGE_ABNORMAL)
2024 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2025 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2027 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2031 && (!JUMP_P (BB_END (bb))
2032 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2033 || any_condjump_p (BB_END (bb))))))
2035 error ("Too many outgoing branch edges from bb %i", bb->index);
2038 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2040 error ("Fallthru edge after unconditional jump %i", bb->index);
2043 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2045 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2048 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2049 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2051 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2054 if (n_call && !CALL_P (BB_END (bb)))
2056 error ("Call edges for non-call insn in bb %i", bb->index);
2060 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2061 && (!JUMP_P (BB_END (bb))
2062 || any_condjump_p (BB_END (bb))
2063 || any_uncondjump_p (BB_END (bb))))
2065 error ("Abnormal edges for no purpose in bb %i", bb->index);
2069 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2070 /* We may have a barrier inside a basic block before dead code
2071 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2072 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2075 if (! BLOCK_FOR_INSN (x))
2077 ("insn %d inside basic block %d but block_for_insn is NULL",
2078 INSN_UID (x), bb->index);
2081 ("insn %d inside basic block %d but block_for_insn is %i",
2082 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2087 /* OK pointers are correct. Now check the header of basic
2088 block. It ought to contain optional CODE_LABEL followed
2089 by NOTE_BASIC_BLOCK. */
2093 if (BB_END (bb) == x)
2095 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2103 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2105 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2110 if (BB_END (bb) == x)
2111 /* Do checks for empty blocks here. */
2114 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2116 if (NOTE_INSN_BASIC_BLOCK_P (x))
2118 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2119 INSN_UID (x), bb->index);
2123 if (x == BB_END (bb))
2126 if (control_flow_insn_p (x))
2128 error ("in basic block %d:", bb->index);
2129 fatal_insn ("flow control insn inside a basic block", x);
2139 /* Verify the CFG and RTL consistency common for both underlying RTL and
2142 Currently it does following checks:
2143 - all checks of rtl_verify_flow_info_1
2144 - check that all insns are in the basic blocks
2145 (except the switch handling code, barriers and notes)
2146 - check that all returns are followed by barriers
2147 - check that all fallthru edge points to the adjacent blocks. */
2149 rtl_verify_flow_info (void)
2152 int err = rtl_verify_flow_info_1 ();
2155 const rtx rtx_first = get_insns ();
2156 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2158 FOR_EACH_BB_REVERSE (bb)
2163 FOR_EACH_EDGE (e, ei, bb->succs)
2164 if (e->flags & EDGE_FALLTHRU)
2170 /* Ensure existence of barrier in BB with no fallthru edges. */
2171 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2172 insn = NEXT_INSN (insn))
2175 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2177 error ("missing barrier after block %i", bb->index);
2182 else if (e->src != ENTRY_BLOCK_PTR
2183 && e->dest != EXIT_BLOCK_PTR)
2187 if (e->src->next_bb != e->dest)
2190 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2191 e->src->index, e->dest->index);
2195 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2196 insn = NEXT_INSN (insn))
2197 if (BARRIER_P (insn)
2198 #ifndef CASE_DROPS_THROUGH
2201 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2205 error ("verify_flow_info: Incorrect fallthru %i->%i",
2206 e->src->index, e->dest->index);
2207 fatal_insn ("wrong insn in the fallthru edge", insn);
2214 last_bb_seen = ENTRY_BLOCK_PTR;
2216 for (x = rtx_first; x; x = NEXT_INSN (x))
2218 if (NOTE_INSN_BASIC_BLOCK_P (x))
2220 bb = NOTE_BASIC_BLOCK (x);
2223 if (bb != last_bb_seen->next_bb)
2224 internal_error ("basic blocks not laid down consecutively");
2226 curr_bb = last_bb_seen = bb;
2231 switch (GET_CODE (x))
2238 /* An addr_vec is placed outside any basic block. */
2240 && JUMP_P (NEXT_INSN (x))
2241 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2242 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2245 /* But in any case, non-deletable labels can appear anywhere. */
2249 fatal_insn ("insn outside basic block", x);
2254 && returnjump_p (x) && ! condjump_p (x)
2255 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2256 fatal_insn ("return not followed by barrier", x);
2257 if (curr_bb && x == BB_END (curr_bb))
2261 if (num_bb_notes != n_basic_blocks)
2263 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2264 num_bb_notes, n_basic_blocks);
2269 /* Assume that the preceding pass has possibly eliminated jump instructions
2270 or converted the unconditional jumps. Eliminate the edges from CFG.
2271 Return true if any edges are eliminated. */
2274 purge_dead_edges (basic_block bb)
2277 rtx insn = BB_END (bb), note;
2278 bool purged = false;
2282 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2283 if (NONJUMP_INSN_P (insn)
2284 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2288 if (! may_trap_p (PATTERN (insn))
2289 || ((eqnote = find_reg_equal_equiv_note (insn))
2290 && ! may_trap_p (XEXP (eqnote, 0))))
2291 remove_note (insn, note);
2294 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2295 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2297 if (e->flags & EDGE_EH)
2299 if (can_throw_internal (BB_END (bb)))
2305 else if (e->flags & EDGE_ABNORMAL_CALL)
2307 if (CALL_P (BB_END (bb))
2308 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2309 || INTVAL (XEXP (note, 0)) >= 0))
2322 bb->flags |= BB_DIRTY;
2332 /* We do care only about conditional jumps and simplejumps. */
2333 if (!any_condjump_p (insn)
2334 && !returnjump_p (insn)
2335 && !simplejump_p (insn))
2338 /* Branch probability/prediction notes are defined only for
2339 condjumps. We've possibly turned condjump into simplejump. */
2340 if (simplejump_p (insn))
2342 note = find_reg_note (insn, REG_BR_PROB, NULL);
2344 remove_note (insn, note);
2345 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2346 remove_note (insn, note);
2349 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2351 /* Avoid abnormal flags to leak from computed jumps turned
2352 into simplejumps. */
2354 e->flags &= ~EDGE_ABNORMAL;
2356 /* See if this edge is one we should keep. */
2357 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2358 /* A conditional jump can fall through into the next
2359 block, so we should keep the edge. */
2364 else if (e->dest != EXIT_BLOCK_PTR
2365 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2366 /* If the destination block is the target of the jump,
2372 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2373 /* If the destination block is the exit block, and this
2374 instruction is a return, then keep the edge. */
2379 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2380 /* Keep the edges that correspond to exceptions thrown by
2381 this instruction and rematerialize the EDGE_ABNORMAL
2382 flag we just cleared above. */
2384 e->flags |= EDGE_ABNORMAL;
2389 /* We do not need this edge. */
2390 bb->flags |= BB_DIRTY;
2395 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2399 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2404 /* Redistribute probabilities. */
2405 if (EDGE_COUNT (bb->succs) == 1)
2407 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2408 EDGE_SUCC (bb, 0)->count = bb->count;
2412 note = find_reg_note (insn, REG_BR_PROB, NULL);
2416 b = BRANCH_EDGE (bb);
2417 f = FALLTHRU_EDGE (bb);
2418 b->probability = INTVAL (XEXP (note, 0));
2419 f->probability = REG_BR_PROB_BASE - b->probability;
2420 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2421 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2426 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2428 /* First, there should not be any EH or ABCALL edges resulting
2429 from non-local gotos and the like. If there were, we shouldn't
2430 have created the sibcall in the first place. Second, there
2431 should of course never have been a fallthru edge. */
2432 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2433 gcc_assert (EDGE_SUCC (bb, 0)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2438 /* If we don't see a jump insn, we don't know exactly why the block would
2439 have been broken at this point. Look for a simple, non-fallthru edge,
2440 as these are only created by conditional branches. If we find such an
2441 edge we know that there used to be a jump here and can then safely
2442 remove all non-fallthru edges. */
2444 FOR_EACH_EDGE (e, ei, bb->succs)
2445 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2454 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2456 if (!(e->flags & EDGE_FALLTHRU))
2458 bb->flags |= BB_DIRTY;
2466 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2468 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2469 EDGE_SUCC (bb, 0)->count = bb->count;
2472 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2477 /* Search all basic blocks for potentially dead edges and purge them. Return
2478 true if some edge has been eliminated. */
2481 purge_all_dead_edges (int update_life_p)
2489 blocks = sbitmap_alloc (last_basic_block);
2490 sbitmap_zero (blocks);
2495 bool purged_here = purge_dead_edges (bb);
2497 purged |= purged_here;
2498 if (purged_here && update_life_p)
2499 SET_BIT (blocks, bb->index);
2502 if (update_life_p && purged)
2503 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2504 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2505 | PROP_KILL_DEAD_CODE);
2508 sbitmap_free (blocks);
2512 /* Same as split_block but update cfg_layout structures. */
2515 cfg_layout_split_block (basic_block bb, void *insnp)
2518 basic_block new_bb = rtl_split_block (bb, insn);
2520 new_bb->rbi->footer = bb->rbi->footer;
2521 bb->rbi->footer = NULL;
2527 /* Redirect Edge to DEST. */
2529 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2531 basic_block src = e->src;
2534 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2537 if (e->dest == dest)
2540 if (e->src != ENTRY_BLOCK_PTR
2541 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2543 src->flags |= BB_DIRTY;
2547 if (e->src == ENTRY_BLOCK_PTR
2548 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2551 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2552 e->src->index, dest->index);
2554 e->src->flags |= BB_DIRTY;
2555 redirect_edge_succ (e, dest);
2559 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2560 in the case the basic block appears to be in sequence. Avoid this
2563 if (e->flags & EDGE_FALLTHRU)
2565 /* Redirect any branch edges unified with the fallthru one. */
2566 if (JUMP_P (BB_END (src))
2567 && label_is_jump_target_p (BB_HEAD (e->dest),
2573 fprintf (dump_file, "Fallthru edge unified with branch "
2574 "%i->%i redirected to %i\n",
2575 e->src->index, e->dest->index, dest->index);
2576 e->flags &= ~EDGE_FALLTHRU;
2577 redirected = redirect_branch_edge (e, dest);
2578 gcc_assert (redirected);
2579 e->flags |= EDGE_FALLTHRU;
2580 e->src->flags |= BB_DIRTY;
2583 /* In case we are redirecting fallthru edge to the branch edge
2584 of conditional jump, remove it. */
2585 if (EDGE_COUNT (src->succs) == 2)
2592 FOR_EACH_EDGE (tmp, ei, src->succs)
2602 if (EDGE_COUNT (src->succs) > (ix + 1))
2603 s = EDGE_SUCC (src, ix + 1);
2605 s = EDGE_SUCC (src, 0);
2608 && any_condjump_p (BB_END (src))
2609 && onlyjump_p (BB_END (src)))
2610 delete_insn (BB_END (src));
2612 ret = redirect_edge_succ_nodup (e, dest);
2614 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2615 e->src->index, e->dest->index, dest->index);
2618 ret = redirect_branch_edge (e, dest);
2620 /* We don't want simplejumps in the insn stream during cfglayout. */
2621 gcc_assert (!simplejump_p (BB_END (src)));
2623 src->flags |= BB_DIRTY;
2627 /* Simple wrapper as we always can redirect fallthru edges. */
2629 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2631 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2633 gcc_assert (redirected);
2637 /* Same as delete_basic_block but update cfg_layout structures. */
2640 cfg_layout_delete_block (basic_block bb)
2642 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2644 if (bb->rbi->header)
2646 next = BB_HEAD (bb);
2648 NEXT_INSN (prev) = bb->rbi->header;
2650 set_first_insn (bb->rbi->header);
2651 PREV_INSN (bb->rbi->header) = prev;
2652 insn = bb->rbi->header;
2653 while (NEXT_INSN (insn))
2654 insn = NEXT_INSN (insn);
2655 NEXT_INSN (insn) = next;
2656 PREV_INSN (next) = insn;
2658 next = NEXT_INSN (BB_END (bb));
2659 if (bb->rbi->footer)
2661 insn = bb->rbi->footer;
2664 if (BARRIER_P (insn))
2666 if (PREV_INSN (insn))
2667 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2669 bb->rbi->footer = NEXT_INSN (insn);
2670 if (NEXT_INSN (insn))
2671 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2675 insn = NEXT_INSN (insn);
2677 if (bb->rbi->footer)
2680 NEXT_INSN (insn) = bb->rbi->footer;
2681 PREV_INSN (bb->rbi->footer) = insn;
2682 while (NEXT_INSN (insn))
2683 insn = NEXT_INSN (insn);
2684 NEXT_INSN (insn) = next;
2686 PREV_INSN (next) = insn;
2688 set_last_insn (insn);
2691 if (bb->next_bb != EXIT_BLOCK_PTR)
2692 to = &bb->next_bb->rbi->header;
2694 to = &cfg_layout_function_footer;
2695 rtl_delete_block (bb);
2698 prev = NEXT_INSN (prev);
2700 prev = get_insns ();
2702 next = PREV_INSN (next);
2704 next = get_last_insn ();
2706 if (next && NEXT_INSN (next) != prev)
2708 remaints = unlink_insn_chain (prev, next);
2710 while (NEXT_INSN (insn))
2711 insn = NEXT_INSN (insn);
2712 NEXT_INSN (insn) = *to;
2714 PREV_INSN (*to) = insn;
2719 /* Return true when blocks A and B can be safely merged. */
2721 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2723 /* If we are partitioning hot/cold basic blocks, we don't want to
2724 mess up unconditional or indirect jumps that cross between hot
2727 Basic block partitioning may result in some jumps that appear to
2728 be optimizable (or blocks that appear to be mergeable), but which really
2729 must be left untouched (they are required to make it safely across
2730 partition boundaries). See the comments at the top of
2731 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2733 if (flag_reorder_blocks_and_partition
2734 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2735 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2736 || BB_PARTITION (a) != BB_PARTITION (b)))
2739 /* There must be exactly one edge in between the blocks. */
2740 return (EDGE_COUNT (a->succs) == 1
2741 && EDGE_SUCC (a, 0)->dest == b
2742 && EDGE_COUNT (b->preds) == 1
2744 /* Must be simple edge. */
2745 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
2746 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2747 /* If the jump insn has side effects,
2748 we can't kill the edge. */
2749 && (!JUMP_P (BB_END (a))
2750 || (reload_completed
2751 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2754 /* Merge block A and B, abort when it is not possible. */
2756 cfg_layout_merge_blocks (basic_block a, basic_block b)
2758 #ifdef ENABLE_CHECKING
2759 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2762 /* If there was a CODE_LABEL beginning B, delete it. */
2763 if (LABEL_P (BB_HEAD (b)))
2764 delete_insn (BB_HEAD (b));
2766 /* We should have fallthru edge in a, or we can do dummy redirection to get
2768 if (JUMP_P (BB_END (a)))
2769 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2770 gcc_assert (!JUMP_P (BB_END (a)));
2772 /* Possible line number notes should appear in between. */
2775 rtx first = BB_END (a), last;
2777 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2778 delete_insn_chain (NEXT_INSN (first), last);
2779 b->rbi->header = NULL;
2782 /* In the case basic blocks are not adjacent, move them around. */
2783 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2785 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2787 emit_insn_after_noloc (first, BB_END (a));
2788 /* Skip possible DELETED_LABEL insn. */
2789 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2790 first = NEXT_INSN (first);
2791 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2793 delete_insn (first);
2795 /* Otherwise just re-associate the instructions. */
2800 for (insn = BB_HEAD (b);
2801 insn != NEXT_INSN (BB_END (b));
2802 insn = NEXT_INSN (insn))
2803 set_block_for_insn (insn, a);
2805 /* Skip possible DELETED_LABEL insn. */
2806 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2807 insn = NEXT_INSN (insn);
2808 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2810 BB_END (a) = BB_END (b);
2814 /* Possible tablejumps and barriers should appear after the block. */
2817 if (!a->rbi->footer)
2818 a->rbi->footer = b->rbi->footer;
2821 rtx last = a->rbi->footer;
2823 while (NEXT_INSN (last))
2824 last = NEXT_INSN (last);
2825 NEXT_INSN (last) = b->rbi->footer;
2826 PREV_INSN (b->rbi->footer) = last;
2828 b->rbi->footer = NULL;
2832 fprintf (dump_file, "Merged blocks %d and %d.\n",
2833 a->index, b->index);
2839 cfg_layout_split_edge (edge e)
2842 basic_block new_bb =
2843 create_basic_block (e->src != ENTRY_BLOCK_PTR
2844 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2847 /* ??? This info is likely going to be out of date very soon, but we must
2848 create it to avoid getting an ICE later. */
2849 if (e->dest->global_live_at_start)
2851 new_bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
2852 new_bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
2853 COPY_REG_SET (new_bb->global_live_at_start,
2854 e->dest->global_live_at_start);
2855 COPY_REG_SET (new_bb->global_live_at_end,
2856 e->dest->global_live_at_start);
2859 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2860 redirect_edge_and_branch_force (e, new_bb);
2865 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2868 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2872 /* Return 1 if BB ends with a call, possibly followed by some
2873 instructions that must stay with the call, 0 otherwise. */
2876 rtl_block_ends_with_call_p (basic_block bb)
2878 rtx insn = BB_END (bb);
2880 while (!CALL_P (insn)
2881 && insn != BB_HEAD (bb)
2882 && keep_with_call_p (insn))
2883 insn = PREV_INSN (insn);
2884 return (CALL_P (insn));
2887 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2890 rtl_block_ends_with_condjump_p (basic_block bb)
2892 return any_condjump_p (BB_END (bb));
2895 /* Return true if we need to add fake edge to exit.
2896 Helper function for rtl_flow_call_edges_add. */
2899 need_fake_edge_p (rtx insn)
2905 && !SIBLING_CALL_P (insn)
2906 && !find_reg_note (insn, REG_NORETURN, NULL)
2907 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2908 && !CONST_OR_PURE_CALL_P (insn)))
2911 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2912 && MEM_VOLATILE_P (PATTERN (insn)))
2913 || (GET_CODE (PATTERN (insn)) == PARALLEL
2914 && asm_noperands (insn) != -1
2915 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2916 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2919 /* Add fake edges to the function exit for any non constant and non noreturn
2920 calls, volatile inline assembly in the bitmap of blocks specified by
2921 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2924 The goal is to expose cases in which entering a basic block does not imply
2925 that all subsequent instructions must be executed. */
2928 rtl_flow_call_edges_add (sbitmap blocks)
2931 int blocks_split = 0;
2932 int last_bb = last_basic_block;
2933 bool check_last_block = false;
2935 if (n_basic_blocks == 0)
2939 check_last_block = true;
2941 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2943 /* In the last basic block, before epilogue generation, there will be
2944 a fallthru edge to EXIT. Special care is required if the last insn
2945 of the last basic block is a call because make_edge folds duplicate
2946 edges, which would result in the fallthru edge also being marked
2947 fake, which would result in the fallthru edge being removed by
2948 remove_fake_edges, which would result in an invalid CFG.
2950 Moreover, we can't elide the outgoing fake edge, since the block
2951 profiler needs to take this into account in order to solve the minimal
2952 spanning tree in the case that the call doesn't return.
2954 Handle this by adding a dummy instruction in a new last basic block. */
2955 if (check_last_block)
2957 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2958 rtx insn = BB_END (bb);
2960 /* Back up past insns that must be kept in the same block as a call. */
2961 while (insn != BB_HEAD (bb)
2962 && keep_with_call_p (insn))
2963 insn = PREV_INSN (insn);
2965 if (need_fake_edge_p (insn))
2969 e = find_edge (bb, EXIT_BLOCK_PTR);
2972 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2973 commit_edge_insertions ();
2978 /* Now add fake edges to the function exit for any non constant
2979 calls since there is no way that we can determine if they will
2982 for (i = 0; i < last_bb; i++)
2984 basic_block bb = BASIC_BLOCK (i);
2991 if (blocks && !TEST_BIT (blocks, i))
2994 for (insn = BB_END (bb); ; insn = prev_insn)
2996 prev_insn = PREV_INSN (insn);
2997 if (need_fake_edge_p (insn))
3000 rtx split_at_insn = insn;
3002 /* Don't split the block between a call and an insn that should
3003 remain in the same block as the call. */
3005 while (split_at_insn != BB_END (bb)
3006 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3007 split_at_insn = NEXT_INSN (split_at_insn);
3009 /* The handling above of the final block before the epilogue
3010 should be enough to verify that there is no edge to the exit
3011 block in CFG already. Calling make_edge in such case would
3012 cause us to mark that edge as fake and remove it later. */
3014 #ifdef ENABLE_CHECKING
3015 if (split_at_insn == BB_END (bb))
3017 e = find_edge (bb, EXIT_BLOCK_PTR);
3018 gcc_assert (e == NULL);
3022 /* Note that the following may create a new basic block
3023 and renumber the existing basic blocks. */
3024 if (split_at_insn != BB_END (bb))
3026 e = split_block (bb, split_at_insn);
3031 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3034 if (insn == BB_HEAD (bb))
3040 verify_flow_info ();
3042 return blocks_split;
3045 /* Implementation of CFG manipulation for linearized RTL. */
3046 struct cfg_hooks rtl_cfg_hooks = {
3048 rtl_verify_flow_info,
3050 rtl_create_basic_block,
3051 rtl_redirect_edge_and_branch,
3052 rtl_redirect_edge_and_branch_force,
3055 rtl_move_block_after,
3056 rtl_can_merge_blocks, /* can_merge_blocks_p */
3060 NULL, /* can_duplicate_block_p */
3061 NULL, /* duplicate_block */
3063 rtl_make_forwarder_block,
3064 rtl_tidy_fallthru_edge,
3065 rtl_block_ends_with_call_p,
3066 rtl_block_ends_with_condjump_p,
3067 rtl_flow_call_edges_add,
3068 NULL, /* execute_on_growing_pred */
3069 NULL /* execute_on_shrinking_pred */
3072 /* Implementation of CFG manipulation for cfg layout RTL, where
3073 basic block connected via fallthru edges does not have to be adjacent.
3074 This representation will hopefully become the default one in future
3075 version of the compiler. */
3077 /* We do not want to declare these functions in a header file, since they
3078 should only be used through the cfghooks interface, and we do not want to
3079 move them here since it would require also moving quite a lot of related
3081 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3082 extern basic_block cfg_layout_duplicate_bb (basic_block);
3084 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3086 rtl_verify_flow_info_1,
3088 cfg_layout_create_basic_block,
3089 cfg_layout_redirect_edge_and_branch,
3090 cfg_layout_redirect_edge_and_branch_force,
3091 cfg_layout_delete_block,
3092 cfg_layout_split_block,
3093 rtl_move_block_after,
3094 cfg_layout_can_merge_blocks_p,
3095 cfg_layout_merge_blocks,
3098 cfg_layout_can_duplicate_bb_p,
3099 cfg_layout_duplicate_bb,
3100 cfg_layout_split_edge,
3101 rtl_make_forwarder_block,
3103 rtl_block_ends_with_call_p,
3104 rtl_block_ends_with_condjump_p,
3105 rtl_flow_call_edges_add,
3106 NULL, /* execute_on_growing_pred */
3107 NULL /* execute_on_shrinking_pred */