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.
373 We need to remove the label from the exception_handler_label list
374 and remove the associated NOTE_INSN_EH_REGION_BEG and
375 NOTE_INSN_EH_REGION_END notes. */
380 maybe_remove_eh_handler (insn);
382 /* Include any jump table following the basic block. */
384 if (tablejump_p (end, NULL, &tmp))
387 /* Include any barrier that may follow the basic block. */
388 tmp = next_nonnote_insn (end);
389 if (tmp && BARRIER_P (tmp))
392 /* Selectively delete the entire chain. */
394 delete_insn_chain (insn, end);
397 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
400 compute_bb_for_insn (void)
406 rtx end = BB_END (bb);
409 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
411 BLOCK_FOR_INSN (insn) = bb;
418 /* Release the basic_block_for_insn array. */
421 free_bb_for_insn (void)
424 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
425 if (!BARRIER_P (insn))
426 BLOCK_FOR_INSN (insn) = NULL;
429 /* Return RTX to emit after when we want to emit code on the entry of function. */
431 entry_of_function (void)
433 return (n_basic_blocks ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
436 /* Update insns block within BB. */
439 update_bb_for_insn (basic_block bb)
443 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
445 if (!BARRIER_P (insn))
446 set_block_for_insn (insn, bb);
447 if (insn == BB_END (bb))
452 /* Creates a new basic block just after basic block B by splitting
453 everything after specified instruction I. */
456 rtl_split_block (basic_block bb, void *insnp)
465 insn = first_insn_after_basic_block_note (bb);
468 insn = PREV_INSN (insn);
470 insn = get_last_insn ();
473 /* We probably should check type of the insn so that we do not create
474 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
476 if (insn == BB_END (bb))
477 emit_note_after (NOTE_INSN_DELETED, insn);
479 /* Create the new basic block. */
480 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
481 BB_COPY_PARTITION (new_bb, bb);
484 /* Redirect the outgoing edges. */
485 new_bb->succs = bb->succs;
487 FOR_EACH_EDGE (e, ei, new_bb->succs)
490 if (bb->global_live_at_start)
492 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
493 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
494 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
496 /* We now have to calculate which registers are live at the end
497 of the split basic block and at the start of the new basic
498 block. Start with those registers that are known to be live
499 at the end of the original basic block and get
500 propagate_block to determine which registers are live. */
501 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
502 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
503 COPY_REG_SET (bb->global_live_at_end,
504 new_bb->global_live_at_start);
505 #ifdef HAVE_conditional_execution
506 /* In the presence of conditional execution we are not able to update
507 liveness precisely. */
508 if (reload_completed)
510 bb->flags |= BB_DIRTY;
511 new_bb->flags |= BB_DIRTY;
519 /* Blocks A and B are to be merged into a single block A. The insns
520 are already contiguous. */
523 rtl_merge_blocks (basic_block a, basic_block b)
525 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
526 rtx del_first = NULL_RTX, del_last = NULL_RTX;
529 /* If there was a CODE_LABEL beginning B, delete it. */
530 if (LABEL_P (b_head))
532 /* Detect basic blocks with nothing but a label. This can happen
533 in particular at the end of a function. */
537 del_first = del_last = b_head;
538 b_head = NEXT_INSN (b_head);
541 /* Delete the basic block note and handle blocks containing just that
543 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
551 b_head = NEXT_INSN (b_head);
554 /* If there was a jump out of A, delete it. */
559 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
561 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
562 || prev == BB_HEAD (a))
568 /* If this was a conditional jump, we need to also delete
569 the insn that set cc0. */
570 if (only_sets_cc0_p (prev))
574 prev = prev_nonnote_insn (prev);
581 a_end = PREV_INSN (del_first);
583 else if (BARRIER_P (NEXT_INSN (a_end)))
584 del_first = NEXT_INSN (a_end);
586 /* Delete everything marked above as well as crap that might be
587 hanging out between the two blocks. */
589 delete_insn_chain (del_first, del_last);
591 /* Reassociate the insns of B with A. */
596 for (x = a_end; x != b_end; x = NEXT_INSN (x))
597 set_block_for_insn (x, a);
599 set_block_for_insn (b_end, a);
607 /* Return true when block A and B can be merged. */
609 rtl_can_merge_blocks (basic_block a,basic_block b)
611 /* If we are partitioning hot/cold basic blocks, we don't want to
612 mess up unconditional or indirect jumps that cross between hot
615 Basic block partitioning may result in some jumps that appear to
616 be optimizable (or blocks that appear to be mergeable), but which really
617 must be left untouched (they are required to make it safely across
618 partition boundaries). See the comments at the top of
619 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
621 if (flag_reorder_blocks_and_partition
622 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
623 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
624 || BB_PARTITION (a) != BB_PARTITION (b)))
627 /* There must be exactly one edge in between the blocks. */
628 return (EDGE_COUNT (a->succs) == 1
629 && EDGE_SUCC (a, 0)->dest == b
630 && EDGE_COUNT (b->preds) == 1
632 /* Must be simple edge. */
633 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
635 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
636 /* If the jump insn has side effects,
637 we can't kill the edge. */
638 && (!JUMP_P (BB_END (a))
640 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
643 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
647 block_label (basic_block block)
649 if (block == EXIT_BLOCK_PTR)
652 if (!LABEL_P (BB_HEAD (block)))
654 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
657 return BB_HEAD (block);
660 /* Attempt to perform edge redirection by replacing possibly complex jump
661 instruction by unconditional jump or removing jump completely. This can
662 apply only if all edges now point to the same block. The parameters and
663 return values are equivalent to redirect_edge_and_branch. */
666 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
668 basic_block src = e->src;
669 rtx insn = BB_END (src), kill_from;
675 /* If we are partitioning hot/cold basic blocks, we don't want to
676 mess up unconditional or indirect jumps that cross between hot
679 Basic block partitioning may result in some jumps that appear to
680 be optimizable (or blocks that appear to be mergeable), but which really
681 must be left untouched (they are required to make it safely across
682 partition boundaries). See the comments at the top of
683 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
685 if (flag_reorder_blocks_and_partition
686 && (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
687 || BB_PARTITION (src) != BB_PARTITION (target)))
690 /* Verify that all targets will be TARGET. */
691 FOR_EACH_EDGE (tmp, ei, src->succs)
692 if (tmp->dest != target && tmp != e)
695 if (tmp || !onlyjump_p (insn))
697 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
700 /* Avoid removing branch with side effects. */
701 set = single_set (insn);
702 if (!set || side_effects_p (set))
705 /* In case we zap a conditional jump, we'll need to kill
706 the cc0 setter too. */
709 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
710 kill_from = PREV_INSN (insn);
713 /* See if we can create the fallthru edge. */
714 if (in_cfglayout || can_fallthru (src, target))
717 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
720 /* Selectively unlink whole insn chain. */
723 rtx insn = src->rbi->footer;
725 delete_insn_chain (kill_from, BB_END (src));
727 /* Remove barriers but keep jumptables. */
730 if (BARRIER_P (insn))
732 if (PREV_INSN (insn))
733 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
735 src->rbi->footer = NEXT_INSN (insn);
736 if (NEXT_INSN (insn))
737 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
741 insn = NEXT_INSN (insn);
745 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
748 /* If this already is simplejump, redirect it. */
749 else if (simplejump_p (insn))
751 if (e->dest == target)
754 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
755 INSN_UID (insn), e->dest->index, target->index);
756 if (!redirect_jump (insn, block_label (target), 0))
758 gcc_assert (target == EXIT_BLOCK_PTR);
763 /* Cannot do anything for target exit block. */
764 else if (target == EXIT_BLOCK_PTR)
767 /* Or replace possibly complicated jump insn by simple jump insn. */
770 rtx target_label = block_label (target);
771 rtx barrier, label, table;
773 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
774 JUMP_LABEL (BB_END (src)) = target_label;
775 LABEL_NUSES (target_label)++;
777 fprintf (dump_file, "Replacing insn %i by jump %i\n",
778 INSN_UID (insn), INSN_UID (BB_END (src)));
781 delete_insn_chain (kill_from, insn);
783 /* Recognize a tablejump that we are converting to a
784 simple jump and remove its associated CODE_LABEL
785 and ADDR_VEC or ADDR_DIFF_VEC. */
786 if (tablejump_p (insn, &label, &table))
787 delete_insn_chain (label, table);
789 barrier = next_nonnote_insn (BB_END (src));
790 if (!barrier || !BARRIER_P (barrier))
791 emit_barrier_after (BB_END (src));
794 if (barrier != NEXT_INSN (BB_END (src)))
796 /* Move the jump before barrier so that the notes
797 which originally were or were created before jump table are
798 inside the basic block. */
799 rtx new_insn = BB_END (src);
802 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
803 tmp = NEXT_INSN (tmp))
804 set_block_for_insn (tmp, src);
806 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
807 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
809 NEXT_INSN (new_insn) = barrier;
810 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
812 PREV_INSN (new_insn) = PREV_INSN (barrier);
813 PREV_INSN (barrier) = new_insn;
818 /* Keep only one edge out and set proper flags. */
819 while (EDGE_COUNT (src->succs) > 1)
822 e = EDGE_SUCC (src, 0);
824 e->flags = EDGE_FALLTHRU;
828 e->probability = REG_BR_PROB_BASE;
829 e->count = src->count;
831 /* We don't want a block to end on a line-number note since that has
832 the potential of changing the code between -g and not -g. */
833 while (NOTE_P (BB_END (e->src))
834 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
835 delete_insn (BB_END (e->src));
837 if (e->dest != target)
838 redirect_edge_succ (e, target);
843 /* Return last loop_beg note appearing after INSN, before start of next
844 basic block. Return INSN if there are no such notes.
846 When emitting jump to redirect a fallthru edge, it should always appear
847 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
848 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
852 last_loop_beg_note (rtx insn)
856 for (insn = NEXT_INSN (insn); insn && NOTE_P (insn)
857 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
858 insn = NEXT_INSN (insn))
859 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
865 /* Redirect edge representing branch of (un)conditional jump or tablejump,
868 redirect_branch_edge (edge e, basic_block target)
871 rtx old_label = BB_HEAD (e->dest);
872 basic_block src = e->src;
873 rtx insn = BB_END (src);
875 /* We can only redirect non-fallthru edges of jump insn. */
876 if (e->flags & EDGE_FALLTHRU)
878 else if (!JUMP_P (insn))
881 /* Recognize a tablejump and adjust all matching cases. */
882 if (tablejump_p (insn, NULL, &tmp))
886 rtx new_label = block_label (target);
888 if (target == EXIT_BLOCK_PTR)
890 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
891 vec = XVEC (PATTERN (tmp), 0);
893 vec = XVEC (PATTERN (tmp), 1);
895 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
896 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
898 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
899 --LABEL_NUSES (old_label);
900 ++LABEL_NUSES (new_label);
903 /* Handle casesi dispatch insns. */
904 if ((tmp = single_set (insn)) != NULL
905 && SET_DEST (tmp) == pc_rtx
906 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
907 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
908 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
910 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
912 --LABEL_NUSES (old_label);
913 ++LABEL_NUSES (new_label);
918 /* ?? We may play the games with moving the named labels from
919 one basic block to the other in case only one computed_jump is
921 if (computed_jump_p (insn)
922 /* A return instruction can't be redirected. */
923 || returnjump_p (insn))
926 /* If the insn doesn't go where we think, we're confused. */
927 gcc_assert (JUMP_LABEL (insn) == old_label);
929 /* If the substitution doesn't succeed, die. This can happen
930 if the back end emitted unrecognizable instructions or if
931 target is exit block on some arches. */
932 if (!redirect_jump (insn, block_label (target), 0))
934 gcc_assert (target == EXIT_BLOCK_PTR);
940 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
941 e->src->index, e->dest->index, target->index);
943 if (e->dest != target)
944 e = redirect_edge_succ_nodup (e, target);
948 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
949 expense of adding new instructions or reordering basic blocks.
951 Function can be also called with edge destination equivalent to the TARGET.
952 Then it should try the simplifications and do nothing if none is possible.
954 Return edge representing the branch if transformation succeeded. Return NULL
956 We still return NULL in case E already destinated TARGET and we didn't
957 managed to simplify instruction stream. */
960 rtl_redirect_edge_and_branch (edge e, basic_block target)
963 basic_block src = e->src;
965 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
968 if (e->dest == target)
971 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
973 src->flags |= BB_DIRTY;
977 ret = redirect_branch_edge (e, target);
981 src->flags |= BB_DIRTY;
985 /* Like force_nonfallthru below, but additionally performs redirection
986 Used by redirect_edge_and_branch_force. */
989 force_nonfallthru_and_redirect (edge e, basic_block target)
991 basic_block jump_block, new_bb = NULL, src = e->src;
994 int abnormal_edge_flags = 0;
996 /* In the case the last instruction is conditional jump to the next
997 instruction, first redirect the jump itself and then continue
998 by creating a basic block afterwards to redirect fallthru edge. */
999 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1000 && any_condjump_p (BB_END (e->src))
1001 /* When called from cfglayout, fallthru edges do not
1002 necessarily go to the next block. */
1003 && e->src->next_bb == e->dest
1004 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1007 edge b = unchecked_make_edge (e->src, target, 0);
1010 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1011 gcc_assert (redirected);
1013 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1016 int prob = INTVAL (XEXP (note, 0));
1018 b->probability = prob;
1019 b->count = e->count * prob / REG_BR_PROB_BASE;
1020 e->probability -= e->probability;
1021 e->count -= b->count;
1022 if (e->probability < 0)
1029 if (e->flags & EDGE_ABNORMAL)
1031 /* Irritating special case - fallthru edge to the same block as abnormal
1033 We can't redirect abnormal edge, but we still can split the fallthru
1034 one and create separate abnormal edge to original destination.
1035 This allows bb-reorder to make such edge non-fallthru. */
1036 gcc_assert (e->dest == target);
1037 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1038 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1042 gcc_assert (e->flags & EDGE_FALLTHRU);
1043 if (e->src == ENTRY_BLOCK_PTR)
1045 /* We can't redirect the entry block. Create an empty block
1046 at the start of the function which we use to add the new
1052 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1054 /* Change the existing edge's source to be the new block, and add
1055 a new edge from the entry block to the new block. */
1057 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1061 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1071 VEC_safe_push (edge, bb->succs, e);
1072 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1076 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1078 /* Create the new structures. */
1080 /* If the old block ended with a tablejump, skip its table
1081 by searching forward from there. Otherwise start searching
1082 forward from the last instruction of the old block. */
1083 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1084 note = BB_END (e->src);
1086 /* Position the new block correctly relative to loop notes. */
1087 note = last_loop_beg_note (note);
1088 note = NEXT_INSN (note);
1090 jump_block = create_basic_block (note, NULL, e->src);
1091 jump_block->count = e->count;
1092 jump_block->frequency = EDGE_FREQUENCY (e);
1093 jump_block->loop_depth = target->loop_depth;
1095 if (target->global_live_at_start)
1097 jump_block->global_live_at_start
1098 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1099 jump_block->global_live_at_end
1100 = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1101 COPY_REG_SET (jump_block->global_live_at_start,
1102 target->global_live_at_start);
1103 COPY_REG_SET (jump_block->global_live_at_end,
1104 target->global_live_at_start);
1107 /* Make sure new block ends up in correct hot/cold section. */
1109 BB_COPY_PARTITION (jump_block, e->src);
1110 if (flag_reorder_blocks_and_partition
1111 && targetm.have_named_sections)
1113 if (BB_PARTITION (jump_block) == BB_COLD_PARTITION)
1115 rtx bb_note, new_note;
1116 for (bb_note = BB_HEAD (jump_block);
1117 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1118 bb_note = NEXT_INSN (bb_note))
1119 if (NOTE_P (bb_note)
1120 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1122 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1124 NOTE_BASIC_BLOCK (new_note) = jump_block;
1126 if (JUMP_P (BB_END (jump_block))
1127 && !any_condjump_p (BB_END (jump_block))
1128 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1129 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1130 (REG_CROSSING_JUMP, NULL_RTX,
1131 REG_NOTES (BB_END (jump_block)));
1135 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1136 new_edge->probability = e->probability;
1137 new_edge->count = e->count;
1139 /* Redirect old edge. */
1140 redirect_edge_pred (e, jump_block);
1141 e->probability = REG_BR_PROB_BASE;
1143 new_bb = jump_block;
1146 jump_block = e->src;
1148 e->flags &= ~EDGE_FALLTHRU;
1149 if (target == EXIT_BLOCK_PTR)
1152 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1159 rtx label = block_label (target);
1160 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1161 JUMP_LABEL (BB_END (jump_block)) = label;
1162 LABEL_NUSES (label)++;
1165 emit_barrier_after (BB_END (jump_block));
1166 redirect_edge_succ_nodup (e, target);
1168 if (abnormal_edge_flags)
1169 make_edge (src, target, abnormal_edge_flags);
1174 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1175 (and possibly create new basic block) to make edge non-fallthru.
1176 Return newly created BB or NULL if none. */
1179 force_nonfallthru (edge e)
1181 return force_nonfallthru_and_redirect (e, e->dest);
1184 /* Redirect edge even at the expense of creating new jump insn or
1185 basic block. Return new basic block if created, NULL otherwise.
1186 Abort if conversion is impossible. */
1189 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1191 if (redirect_edge_and_branch (e, target)
1192 || e->dest == target)
1195 /* In case the edge redirection failed, try to force it to be non-fallthru
1196 and redirect newly created simplejump. */
1197 return force_nonfallthru_and_redirect (e, target);
1200 /* The given edge should potentially be a fallthru edge. If that is in
1201 fact true, delete the jump and barriers that are in the way. */
1204 rtl_tidy_fallthru_edge (edge e)
1207 basic_block b = e->src, c = b->next_bb;
1211 FOR_EACH_EDGE (e2, ei, b->succs)
1215 /* ??? In a late-running flow pass, other folks may have deleted basic
1216 blocks by nopping out blocks, leaving multiple BARRIERs between here
1217 and the target label. They ought to be chastized and fixed.
1219 We can also wind up with a sequence of undeletable labels between
1220 one block and the next.
1222 So search through a sequence of barriers, labels, and notes for
1223 the head of block C and assert that we really do fall through. */
1225 for (q = NEXT_INSN (BB_END (b)); q != BB_HEAD (c); q = NEXT_INSN (q))
1229 /* Remove what will soon cease being the jump insn from the source block.
1230 If block B consisted only of this single jump, turn it into a deleted
1235 && (any_uncondjump_p (q)
1236 || (EDGE_SUCC (b, 0) == e && ei.index == EDGE_COUNT (b->succs) - 1)))
1239 /* If this was a conditional jump, we need to also delete
1240 the insn that set cc0. */
1241 if (any_condjump_p (q) && only_sets_cc0_p (PREV_INSN (q)))
1247 /* We don't want a block to end on a line-number note since that has
1248 the potential of changing the code between -g and not -g. */
1249 while (NOTE_P (q) && NOTE_LINE_NUMBER (q) >= 0)
1253 /* Selectively unlink the sequence. */
1254 if (q != PREV_INSN (BB_HEAD (c)))
1255 delete_insn_chain (NEXT_INSN (q), PREV_INSN (BB_HEAD (c)));
1257 e->flags |= EDGE_FALLTHRU;
1260 /* Helper function for split_edge. Return true in case edge BB2 to BB1
1261 is back edge of syntactic loop. */
1264 back_edge_of_syntactic_loop_p (basic_block bb1, basic_block bb2)
1273 /* ??? Could we guarantee that bb indices are monotone, so that we could
1274 just compare them? */
1275 for (bb = bb1; bb && bb != bb2; bb = bb->next_bb)
1281 for (insn = BB_END (bb1); insn != BB_HEAD (bb2) && count >= 0;
1282 insn = NEXT_INSN (insn))
1285 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
1287 else if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_END)
1294 /* Should move basic block BB after basic block AFTER. NIY. */
1297 rtl_move_block_after (basic_block bb ATTRIBUTE_UNUSED,
1298 basic_block after ATTRIBUTE_UNUSED)
1303 /* Split a (typically critical) edge. Return the new block.
1304 Abort on abnormal edges.
1306 ??? The code generally expects to be called on critical edges.
1307 The case of a block ending in an unconditional jump to a
1308 block with multiple predecessors is not handled optimally. */
1311 rtl_split_edge (edge edge_in)
1316 /* Abnormal edges cannot be split. */
1317 gcc_assert (!(edge_in->flags & EDGE_ABNORMAL));
1319 /* We are going to place the new block in front of edge destination.
1320 Avoid existence of fallthru predecessors. */
1321 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1326 FOR_EACH_EDGE (e, ei, edge_in->dest->preds)
1327 if (e->flags & EDGE_FALLTHRU)
1331 force_nonfallthru (e);
1334 /* Create the basic block note.
1336 Where we place the note can have a noticeable impact on the generated
1337 code. Consider this cfg:
1347 If we need to insert an insn on the edge from block 0 to block 1,
1348 we want to ensure the instructions we insert are outside of any
1349 loop notes that physically sit between block 0 and block 1. Otherwise
1350 we confuse the loop optimizer into thinking the loop is a phony. */
1352 if (edge_in->dest != EXIT_BLOCK_PTR
1353 && PREV_INSN (BB_HEAD (edge_in->dest))
1354 && NOTE_P (PREV_INSN (BB_HEAD (edge_in->dest)))
1355 && (NOTE_LINE_NUMBER (PREV_INSN (BB_HEAD (edge_in->dest)))
1356 == NOTE_INSN_LOOP_BEG)
1357 && !back_edge_of_syntactic_loop_p (edge_in->dest, edge_in->src))
1358 before = PREV_INSN (BB_HEAD (edge_in->dest));
1359 else if (edge_in->dest != EXIT_BLOCK_PTR)
1360 before = BB_HEAD (edge_in->dest);
1364 /* If this is a fall through edge to the exit block, the blocks might be
1365 not adjacent, and the right place is the after the source. */
1366 if (edge_in->flags & EDGE_FALLTHRU && edge_in->dest == EXIT_BLOCK_PTR)
1368 before = NEXT_INSN (BB_END (edge_in->src));
1371 && NOTE_LINE_NUMBER (before) == NOTE_INSN_LOOP_END)
1372 before = NEXT_INSN (before);
1373 bb = create_basic_block (before, NULL, edge_in->src);
1374 BB_COPY_PARTITION (bb, edge_in->src);
1378 bb = create_basic_block (before, NULL, edge_in->dest->prev_bb);
1379 /* ??? Why not edge_in->dest->prev_bb here? */
1380 BB_COPY_PARTITION (bb, edge_in->dest);
1383 /* ??? This info is likely going to be out of date very soon. */
1384 if (edge_in->dest->global_live_at_start)
1386 bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1387 bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
1388 COPY_REG_SET (bb->global_live_at_start,
1389 edge_in->dest->global_live_at_start);
1390 COPY_REG_SET (bb->global_live_at_end,
1391 edge_in->dest->global_live_at_start);
1394 make_single_succ_edge (bb, edge_in->dest, EDGE_FALLTHRU);
1396 /* For non-fallthru edges, we must adjust the predecessor's
1397 jump instruction to target our new block. */
1398 if ((edge_in->flags & EDGE_FALLTHRU) == 0)
1400 edge redirected = redirect_edge_and_branch (edge_in, bb);
1401 gcc_assert (redirected);
1404 redirect_edge_succ (edge_in, bb);
1409 /* Queue instructions for insertion on an edge between two basic blocks.
1410 The new instructions and basic blocks (if any) will not appear in the
1411 CFG until commit_edge_insertions is called. */
1414 insert_insn_on_edge (rtx pattern, edge e)
1416 /* We cannot insert instructions on an abnormal critical edge.
1417 It will be easier to find the culprit if we die now. */
1418 gcc_assert (!((e->flags & EDGE_ABNORMAL) && EDGE_CRITICAL_P (e)));
1420 if (e->insns.r == NULL_RTX)
1423 push_to_sequence (e->insns.r);
1425 emit_insn (pattern);
1427 e->insns.r = get_insns ();
1431 /* Called from safe_insert_insn_on_edge through note_stores, marks live
1432 registers that are killed by the store. */
1434 mark_killed_regs (rtx reg, rtx set ATTRIBUTE_UNUSED, void *data)
1436 regset killed = data;
1439 if (GET_CODE (reg) == SUBREG)
1440 reg = SUBREG_REG (reg);
1443 regno = REGNO (reg);
1444 if (regno >= FIRST_PSEUDO_REGISTER)
1445 SET_REGNO_REG_SET (killed, regno);
1448 for (i = 0; i < (int) hard_regno_nregs[regno][GET_MODE (reg)]; i++)
1449 SET_REGNO_REG_SET (killed, regno + i);
1453 /* Similar to insert_insn_on_edge, tries to put INSN to edge E. Additionally
1454 it checks whether this will not clobber the registers that are live on the
1455 edge (i.e. it requires liveness information to be up-to-date) and if there
1456 are some, then it tries to save and restore them. Returns true if
1459 safe_insert_insn_on_edge (rtx insn, edge e)
1462 regset_head killed_head;
1463 regset killed = INITIALIZE_REG_SET (killed_head);
1464 rtx save_regs = NULL_RTX;
1467 enum machine_mode mode;
1468 reg_set_iterator rsi;
1470 #ifdef AVOID_CCMODE_COPIES
1476 for (x = insn; x; x = NEXT_INSN (x))
1478 note_stores (PATTERN (x), mark_killed_regs, killed);
1479 bitmap_and_into (killed, e->dest->global_live_at_start);
1481 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno, rsi)
1483 mode = regno < FIRST_PSEUDO_REGISTER
1484 ? reg_raw_mode[regno]
1485 : GET_MODE (regno_reg_rtx[regno]);
1486 if (mode == VOIDmode)
1489 if (noccmode && mode == CCmode)
1492 save_regs = alloc_EXPR_LIST (0,
1495 gen_raw_REG (mode, regno)),
1504 for (x = save_regs; x; x = XEXP (x, 1))
1506 from = XEXP (XEXP (x, 0), 1);
1507 to = XEXP (XEXP (x, 0), 0);
1508 emit_move_insn (to, from);
1511 for (x = save_regs; x; x = XEXP (x, 1))
1513 from = XEXP (XEXP (x, 0), 0);
1514 to = XEXP (XEXP (x, 0), 1);
1515 emit_move_insn (to, from);
1517 insn = get_insns ();
1519 free_EXPR_LIST_list (&save_regs);
1521 insert_insn_on_edge (insn, e);
1523 FREE_REG_SET (killed);
1527 /* Update the CFG for the instructions queued on edge E. */
1530 commit_one_edge_insertion (edge e, int watch_calls)
1532 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1533 basic_block bb = NULL;
1535 /* Pull the insns off the edge now since the edge might go away. */
1537 e->insns.r = NULL_RTX;
1539 /* Special case -- avoid inserting code between call and storing
1540 its return value. */
1541 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1542 && EDGE_COUNT (e->dest->preds) == 1
1543 && e->src != ENTRY_BLOCK_PTR
1544 && CALL_P (BB_END (e->src)))
1546 rtx next = next_nonnote_insn (BB_END (e->src));
1548 after = BB_HEAD (e->dest);
1549 /* The first insn after the call may be a stack pop, skip it. */
1551 && keep_with_call_p (next))
1554 next = next_nonnote_insn (next);
1558 if (!before && !after)
1560 /* Figure out where to put these things. If the destination has
1561 one predecessor, insert there. Except for the exit block. */
1562 if (EDGE_COUNT (e->dest->preds) == 1 && e->dest != EXIT_BLOCK_PTR)
1566 /* Get the location correct wrt a code label, and "nice" wrt
1567 a basic block note, and before everything else. */
1570 tmp = NEXT_INSN (tmp);
1571 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1572 tmp = NEXT_INSN (tmp);
1575 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1576 tmp = NEXT_INSN (tmp);
1577 if (tmp == BB_HEAD (bb))
1580 after = PREV_INSN (tmp);
1582 after = get_last_insn ();
1585 /* If the source has one successor and the edge is not abnormal,
1586 insert there. Except for the entry block. */
1587 else if ((e->flags & EDGE_ABNORMAL) == 0
1588 && EDGE_COUNT (e->src->succs) == 1
1589 && e->src != ENTRY_BLOCK_PTR)
1593 /* It is possible to have a non-simple jump here. Consider a target
1594 where some forms of unconditional jumps clobber a register. This
1595 happens on the fr30 for example.
1597 We know this block has a single successor, so we can just emit
1598 the queued insns before the jump. */
1599 if (JUMP_P (BB_END (bb)))
1600 for (before = BB_END (bb);
1601 NOTE_P (PREV_INSN (before))
1602 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1603 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1607 /* We'd better be fallthru, or we've lost track of
1609 gcc_assert (e->flags & EDGE_FALLTHRU);
1611 after = BB_END (bb);
1614 /* Otherwise we must split the edge. */
1617 bb = split_edge (e);
1618 after = BB_END (bb);
1620 if (flag_reorder_blocks_and_partition
1621 && targetm.have_named_sections
1622 && e->src != ENTRY_BLOCK_PTR
1623 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1624 && !(e->flags & EDGE_CROSSING))
1626 rtx bb_note, new_note, cur_insn;
1629 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1630 cur_insn = NEXT_INSN (cur_insn))
1631 if (NOTE_P (cur_insn)
1632 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1638 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1640 NOTE_BASIC_BLOCK (new_note) = bb;
1641 if (JUMP_P (BB_END (bb))
1642 && !any_condjump_p (BB_END (bb))
1643 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
1644 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1645 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1646 if (after == bb_note)
1652 /* Now that we've found the spot, do the insertion. */
1656 emit_insn_before_noloc (insns, before);
1657 last = prev_nonnote_insn (before);
1660 last = emit_insn_after_noloc (insns, after);
1662 if (returnjump_p (last))
1664 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1665 This is not currently a problem because this only happens
1666 for the (single) epilogue, which already has a fallthru edge
1669 e = EDGE_SUCC (bb, 0);
1670 gcc_assert (e->dest == EXIT_BLOCK_PTR
1671 && EDGE_COUNT (bb->succs) == 1 && (e->flags & EDGE_FALLTHRU));
1673 e->flags &= ~EDGE_FALLTHRU;
1674 emit_barrier_after (last);
1677 delete_insn (before);
1680 gcc_assert (!JUMP_P (last));
1682 /* Mark the basic block for find_sub_basic_blocks. */
1686 /* Update the CFG for all queued instructions. */
1689 commit_edge_insertions (void)
1693 bool changed = false;
1695 #ifdef ENABLE_CHECKING
1696 verify_flow_info ();
1699 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1704 FOR_EACH_EDGE (e, ei, bb->succs)
1708 commit_one_edge_insertion (e, false);
1715 blocks = sbitmap_alloc (last_basic_block);
1716 sbitmap_zero (blocks);
1720 SET_BIT (blocks, bb->index);
1721 /* Check for forgotten bb->aux values before commit_edge_insertions
1723 gcc_assert (bb->aux == &bb->aux);
1726 find_many_sub_basic_blocks (blocks);
1727 sbitmap_free (blocks);
1730 /* Update the CFG for all queued instructions, taking special care of inserting
1731 code on edges between call and storing its return value. */
1734 commit_edge_insertions_watch_calls (void)
1738 bool changed = false;
1740 #ifdef ENABLE_CHECKING
1741 verify_flow_info ();
1744 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1749 FOR_EACH_EDGE (e, ei, bb->succs)
1753 commit_one_edge_insertion (e, true);
1760 blocks = sbitmap_alloc (last_basic_block);
1761 sbitmap_zero (blocks);
1765 SET_BIT (blocks, bb->index);
1766 /* Check for forgotten bb->aux values before commit_edge_insertions
1768 gcc_assert (bb->aux == &bb->aux);
1771 find_many_sub_basic_blocks (blocks);
1772 sbitmap_free (blocks);
1775 /* Print out RTL-specific basic block information (live information
1776 at start and end). */
1779 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1785 s_indent = alloca ((size_t) indent + 1);
1786 memset (s_indent, ' ', (size_t) indent);
1787 s_indent[indent] = '\0';
1789 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1790 dump_regset (bb->global_live_at_start, outf);
1793 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1794 insn = NEXT_INSN (insn))
1795 print_rtl_single (outf, insn);
1797 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1798 dump_regset (bb->global_live_at_end, outf);
1802 /* Like print_rtl, but also print out live information for the start of each
1806 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1811 fprintf (outf, "(nil)\n");
1814 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1815 int max_uid = get_max_uid ();
1816 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1817 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1818 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1822 FOR_EACH_BB_REVERSE (bb)
1826 start[INSN_UID (BB_HEAD (bb))] = bb;
1827 end[INSN_UID (BB_END (bb))] = bb;
1828 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1830 enum bb_state state = IN_MULTIPLE_BB;
1832 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1834 in_bb_p[INSN_UID (x)] = state;
1836 if (x == BB_END (bb))
1841 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1845 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1847 fprintf (outf, ";; Start of basic block %d, registers live:",
1849 dump_regset (bb->global_live_at_start, outf);
1853 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1854 && !NOTE_P (tmp_rtx)
1855 && !BARRIER_P (tmp_rtx))
1856 fprintf (outf, ";; Insn is not within a basic block\n");
1857 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1858 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1860 did_output = print_rtl_single (outf, tmp_rtx);
1862 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1864 fprintf (outf, ";; End of basic block %d, registers live:\n",
1866 dump_regset (bb->global_live_at_end, outf);
1879 if (current_function_epilogue_delay_list != 0)
1881 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1882 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1883 tmp_rtx = XEXP (tmp_rtx, 1))
1884 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1889 update_br_prob_note (basic_block bb)
1892 if (!JUMP_P (BB_END (bb)))
1894 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1895 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1897 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1900 /* Verify the CFG and RTL consistency common for both underlying RTL and
1903 Currently it does following checks:
1905 - test head/end pointers
1906 - overlapping of basic blocks
1907 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1908 - tails of basic blocks (ensure that boundary is necessary)
1909 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1910 and NOTE_INSN_BASIC_BLOCK
1911 - verify that no fall_thru edge crosses hot/cold partition boundaries
1913 In future it can be extended check a lot of other stuff as well
1914 (reachability of basic blocks, life information, etc. etc.). */
1917 rtl_verify_flow_info_1 (void)
1919 const int max_uid = get_max_uid ();
1920 rtx last_head = get_last_insn ();
1921 basic_block *bb_info;
1924 basic_block bb, last_bb_seen;
1926 bb_info = xcalloc (max_uid, sizeof (basic_block));
1928 /* Check bb chain & numbers. */
1929 last_bb_seen = ENTRY_BLOCK_PTR;
1931 FOR_EACH_BB_REVERSE (bb)
1933 rtx head = BB_HEAD (bb);
1934 rtx end = BB_END (bb);
1936 /* Verify the end of the basic block is in the INSN chain. */
1937 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1943 error ("end insn %d for block %d not found in the insn stream",
1944 INSN_UID (end), bb->index);
1948 /* Work backwards from the end to the head of the basic block
1949 to verify the head is in the RTL chain. */
1950 for (; x != NULL_RTX; x = PREV_INSN (x))
1952 /* While walking over the insn chain, verify insns appear
1953 in only one basic block and initialize the BB_INFO array
1954 used by other passes. */
1955 if (bb_info[INSN_UID (x)] != NULL)
1957 error ("insn %d is in multiple basic blocks (%d and %d)",
1958 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1962 bb_info[INSN_UID (x)] = bb;
1969 error ("head insn %d for block %d not found in the insn stream",
1970 INSN_UID (head), bb->index);
1977 /* Now check the basic blocks (boundaries etc.) */
1978 FOR_EACH_BB_REVERSE (bb)
1980 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1981 edge e, fallthru = NULL;
1985 if (INSN_P (BB_END (bb))
1986 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1987 && EDGE_COUNT (bb->succs) >= 2
1988 && any_condjump_p (BB_END (bb)))
1990 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1991 && profile_status != PROFILE_ABSENT)
1993 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1994 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
1998 FOR_EACH_EDGE (e, ei, bb->succs)
2000 if (e->flags & EDGE_FALLTHRU)
2002 n_fallthru++, fallthru = e;
2003 if ((e->flags & EDGE_CROSSING)
2004 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
2005 && e->src != ENTRY_BLOCK_PTR
2006 && e->dest != EXIT_BLOCK_PTR))
2008 error ("Fallthru edge crosses section boundary (bb %i)",
2014 if ((e->flags & ~(EDGE_DFS_BACK
2016 | EDGE_IRREDUCIBLE_LOOP
2018 | EDGE_CROSSING)) == 0)
2021 if (e->flags & EDGE_ABNORMAL_CALL)
2024 if (e->flags & EDGE_EH)
2026 else if (e->flags & EDGE_ABNORMAL)
2030 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2031 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2033 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2037 && (!JUMP_P (BB_END (bb))
2038 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2039 || any_condjump_p (BB_END (bb))))))
2041 error ("Too many outgoing branch edges from bb %i", bb->index);
2044 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2046 error ("Fallthru edge after unconditional jump %i", bb->index);
2049 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2051 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2054 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2055 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2057 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2060 if (n_call && !CALL_P (BB_END (bb)))
2062 error ("Call edges for non-call insn in bb %i", bb->index);
2066 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2067 && (!JUMP_P (BB_END (bb))
2068 || any_condjump_p (BB_END (bb))
2069 || any_uncondjump_p (BB_END (bb))))
2071 error ("Abnormal edges for no purpose in bb %i", bb->index);
2075 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2076 /* We may have a barrier inside a basic block before dead code
2077 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2078 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2081 if (! BLOCK_FOR_INSN (x))
2083 ("insn %d inside basic block %d but block_for_insn is NULL",
2084 INSN_UID (x), bb->index);
2087 ("insn %d inside basic block %d but block_for_insn is %i",
2088 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2093 /* OK pointers are correct. Now check the header of basic
2094 block. It ought to contain optional CODE_LABEL followed
2095 by NOTE_BASIC_BLOCK. */
2099 if (BB_END (bb) == x)
2101 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2109 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2111 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2116 if (BB_END (bb) == x)
2117 /* Do checks for empty blocks here. */
2120 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2122 if (NOTE_INSN_BASIC_BLOCK_P (x))
2124 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2125 INSN_UID (x), bb->index);
2129 if (x == BB_END (bb))
2132 if (control_flow_insn_p (x))
2134 error ("in basic block %d:", bb->index);
2135 fatal_insn ("flow control insn inside a basic block", x);
2145 /* Verify the CFG and RTL consistency common for both underlying RTL and
2148 Currently it does following checks:
2149 - all checks of rtl_verify_flow_info_1
2150 - check that all insns are in the basic blocks
2151 (except the switch handling code, barriers and notes)
2152 - check that all returns are followed by barriers
2153 - check that all fallthru edge points to the adjacent blocks. */
2155 rtl_verify_flow_info (void)
2158 int err = rtl_verify_flow_info_1 ();
2161 const rtx rtx_first = get_insns ();
2162 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2164 FOR_EACH_BB_REVERSE (bb)
2169 FOR_EACH_EDGE (e, ei, bb->succs)
2170 if (e->flags & EDGE_FALLTHRU)
2176 /* Ensure existence of barrier in BB with no fallthru edges. */
2177 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2178 insn = NEXT_INSN (insn))
2181 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2183 error ("missing barrier after block %i", bb->index);
2188 else if (e->src != ENTRY_BLOCK_PTR
2189 && e->dest != EXIT_BLOCK_PTR)
2193 if (e->src->next_bb != e->dest)
2196 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2197 e->src->index, e->dest->index);
2201 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2202 insn = NEXT_INSN (insn))
2203 if (BARRIER_P (insn)
2204 #ifndef CASE_DROPS_THROUGH
2207 || (INSN_P (insn) && ! JUMP_TABLE_DATA_P (insn))
2211 error ("verify_flow_info: Incorrect fallthru %i->%i",
2212 e->src->index, e->dest->index);
2213 fatal_insn ("wrong insn in the fallthru edge", insn);
2220 last_bb_seen = ENTRY_BLOCK_PTR;
2222 for (x = rtx_first; x; x = NEXT_INSN (x))
2224 if (NOTE_INSN_BASIC_BLOCK_P (x))
2226 bb = NOTE_BASIC_BLOCK (x);
2229 if (bb != last_bb_seen->next_bb)
2230 internal_error ("basic blocks not laid down consecutively");
2232 curr_bb = last_bb_seen = bb;
2237 switch (GET_CODE (x))
2244 /* An addr_vec is placed outside any basic block. */
2246 && JUMP_P (NEXT_INSN (x))
2247 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2248 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2251 /* But in any case, non-deletable labels can appear anywhere. */
2255 fatal_insn ("insn outside basic block", x);
2260 && returnjump_p (x) && ! condjump_p (x)
2261 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2262 fatal_insn ("return not followed by barrier", x);
2263 if (curr_bb && x == BB_END (curr_bb))
2267 if (num_bb_notes != n_basic_blocks)
2269 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2270 num_bb_notes, n_basic_blocks);
2275 /* Assume that the preceding pass has possibly eliminated jump instructions
2276 or converted the unconditional jumps. Eliminate the edges from CFG.
2277 Return true if any edges are eliminated. */
2280 purge_dead_edges (basic_block bb)
2283 rtx insn = BB_END (bb), note;
2284 bool purged = false;
2288 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2289 if (NONJUMP_INSN_P (insn)
2290 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2294 if (! may_trap_p (PATTERN (insn))
2295 || ((eqnote = find_reg_equal_equiv_note (insn))
2296 && ! may_trap_p (XEXP (eqnote, 0))))
2297 remove_note (insn, note);
2300 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2301 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2303 if (e->flags & EDGE_EH)
2305 if (can_throw_internal (BB_END (bb)))
2311 else if (e->flags & EDGE_ABNORMAL_CALL)
2313 if (CALL_P (BB_END (bb))
2314 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2315 || INTVAL (XEXP (note, 0)) >= 0))
2328 bb->flags |= BB_DIRTY;
2338 /* We do care only about conditional jumps and simplejumps. */
2339 if (!any_condjump_p (insn)
2340 && !returnjump_p (insn)
2341 && !simplejump_p (insn))
2344 /* Branch probability/prediction notes are defined only for
2345 condjumps. We've possibly turned condjump into simplejump. */
2346 if (simplejump_p (insn))
2348 note = find_reg_note (insn, REG_BR_PROB, NULL);
2350 remove_note (insn, note);
2351 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2352 remove_note (insn, note);
2355 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2357 /* Avoid abnormal flags to leak from computed jumps turned
2358 into simplejumps. */
2360 e->flags &= ~EDGE_ABNORMAL;
2362 /* See if this edge is one we should keep. */
2363 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2364 /* A conditional jump can fall through into the next
2365 block, so we should keep the edge. */
2370 else if (e->dest != EXIT_BLOCK_PTR
2371 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2372 /* If the destination block is the target of the jump,
2378 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2379 /* If the destination block is the exit block, and this
2380 instruction is a return, then keep the edge. */
2385 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2386 /* Keep the edges that correspond to exceptions thrown by
2387 this instruction and rematerialize the EDGE_ABNORMAL
2388 flag we just cleared above. */
2390 e->flags |= EDGE_ABNORMAL;
2395 /* We do not need this edge. */
2396 bb->flags |= BB_DIRTY;
2401 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2405 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2410 /* Redistribute probabilities. */
2411 if (EDGE_COUNT (bb->succs) == 1)
2413 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2414 EDGE_SUCC (bb, 0)->count = bb->count;
2418 note = find_reg_note (insn, REG_BR_PROB, NULL);
2422 b = BRANCH_EDGE (bb);
2423 f = FALLTHRU_EDGE (bb);
2424 b->probability = INTVAL (XEXP (note, 0));
2425 f->probability = REG_BR_PROB_BASE - b->probability;
2426 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2427 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2432 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2434 /* First, there should not be any EH or ABCALL edges resulting
2435 from non-local gotos and the like. If there were, we shouldn't
2436 have created the sibcall in the first place. Second, there
2437 should of course never have been a fallthru edge. */
2438 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2439 gcc_assert (EDGE_SUCC (bb, 0)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2444 /* If we don't see a jump insn, we don't know exactly why the block would
2445 have been broken at this point. Look for a simple, non-fallthru edge,
2446 as these are only created by conditional branches. If we find such an
2447 edge we know that there used to be a jump here and can then safely
2448 remove all non-fallthru edges. */
2450 FOR_EACH_EDGE (e, ei, bb->succs)
2451 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2460 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2462 if (!(e->flags & EDGE_FALLTHRU))
2464 bb->flags |= BB_DIRTY;
2472 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2474 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2475 EDGE_SUCC (bb, 0)->count = bb->count;
2478 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2483 /* Search all basic blocks for potentially dead edges and purge them. Return
2484 true if some edge has been eliminated. */
2487 purge_all_dead_edges (int update_life_p)
2495 blocks = sbitmap_alloc (last_basic_block);
2496 sbitmap_zero (blocks);
2501 bool purged_here = purge_dead_edges (bb);
2503 purged |= purged_here;
2504 if (purged_here && update_life_p)
2505 SET_BIT (blocks, bb->index);
2508 if (update_life_p && purged)
2509 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2510 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2511 | PROP_KILL_DEAD_CODE);
2514 sbitmap_free (blocks);
2518 /* Same as split_block but update cfg_layout structures. */
2521 cfg_layout_split_block (basic_block bb, void *insnp)
2524 basic_block new_bb = rtl_split_block (bb, insn);
2526 new_bb->rbi->footer = bb->rbi->footer;
2527 bb->rbi->footer = NULL;
2533 /* Redirect Edge to DEST. */
2535 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2537 basic_block src = e->src;
2540 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2543 if (e->dest == dest)
2546 if (e->src != ENTRY_BLOCK_PTR
2547 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2549 src->flags |= BB_DIRTY;
2553 if (e->src == ENTRY_BLOCK_PTR
2554 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2557 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2558 e->src->index, dest->index);
2560 e->src->flags |= BB_DIRTY;
2561 redirect_edge_succ (e, dest);
2565 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2566 in the case the basic block appears to be in sequence. Avoid this
2569 if (e->flags & EDGE_FALLTHRU)
2571 /* Redirect any branch edges unified with the fallthru one. */
2572 if (JUMP_P (BB_END (src))
2573 && label_is_jump_target_p (BB_HEAD (e->dest),
2579 fprintf (dump_file, "Fallthru edge unified with branch "
2580 "%i->%i redirected to %i\n",
2581 e->src->index, e->dest->index, dest->index);
2582 e->flags &= ~EDGE_FALLTHRU;
2583 redirected = redirect_branch_edge (e, dest);
2584 gcc_assert (redirected);
2585 e->flags |= EDGE_FALLTHRU;
2586 e->src->flags |= BB_DIRTY;
2589 /* In case we are redirecting fallthru edge to the branch edge
2590 of conditional jump, remove it. */
2591 if (EDGE_COUNT (src->succs) == 2)
2598 FOR_EACH_EDGE (tmp, ei, src->succs)
2608 if (EDGE_COUNT (src->succs) > (ix + 1))
2609 s = EDGE_SUCC (src, ix + 1);
2611 s = EDGE_SUCC (src, 0);
2614 && any_condjump_p (BB_END (src))
2615 && onlyjump_p (BB_END (src)))
2616 delete_insn (BB_END (src));
2618 ret = redirect_edge_succ_nodup (e, dest);
2620 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2621 e->src->index, e->dest->index, dest->index);
2624 ret = redirect_branch_edge (e, dest);
2626 /* We don't want simplejumps in the insn stream during cfglayout. */
2627 gcc_assert (!simplejump_p (BB_END (src)));
2629 src->flags |= BB_DIRTY;
2633 /* Simple wrapper as we always can redirect fallthru edges. */
2635 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2637 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2639 gcc_assert (redirected);
2643 /* Same as delete_basic_block but update cfg_layout structures. */
2646 cfg_layout_delete_block (basic_block bb)
2648 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2650 if (bb->rbi->header)
2652 next = BB_HEAD (bb);
2654 NEXT_INSN (prev) = bb->rbi->header;
2656 set_first_insn (bb->rbi->header);
2657 PREV_INSN (bb->rbi->header) = prev;
2658 insn = bb->rbi->header;
2659 while (NEXT_INSN (insn))
2660 insn = NEXT_INSN (insn);
2661 NEXT_INSN (insn) = next;
2662 PREV_INSN (next) = insn;
2664 next = NEXT_INSN (BB_END (bb));
2665 if (bb->rbi->footer)
2667 insn = bb->rbi->footer;
2670 if (BARRIER_P (insn))
2672 if (PREV_INSN (insn))
2673 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2675 bb->rbi->footer = NEXT_INSN (insn);
2676 if (NEXT_INSN (insn))
2677 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2681 insn = NEXT_INSN (insn);
2683 if (bb->rbi->footer)
2686 NEXT_INSN (insn) = bb->rbi->footer;
2687 PREV_INSN (bb->rbi->footer) = insn;
2688 while (NEXT_INSN (insn))
2689 insn = NEXT_INSN (insn);
2690 NEXT_INSN (insn) = next;
2692 PREV_INSN (next) = insn;
2694 set_last_insn (insn);
2697 if (bb->next_bb != EXIT_BLOCK_PTR)
2698 to = &bb->next_bb->rbi->header;
2700 to = &cfg_layout_function_footer;
2701 rtl_delete_block (bb);
2704 prev = NEXT_INSN (prev);
2706 prev = get_insns ();
2708 next = PREV_INSN (next);
2710 next = get_last_insn ();
2712 if (next && NEXT_INSN (next) != prev)
2714 remaints = unlink_insn_chain (prev, next);
2716 while (NEXT_INSN (insn))
2717 insn = NEXT_INSN (insn);
2718 NEXT_INSN (insn) = *to;
2720 PREV_INSN (*to) = insn;
2725 /* Return true when blocks A and B can be safely merged. */
2727 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2729 /* If we are partitioning hot/cold basic blocks, we don't want to
2730 mess up unconditional or indirect jumps that cross between hot
2733 Basic block partitioning may result in some jumps that appear to
2734 be optimizable (or blocks that appear to be mergeable), but which really
2735 must be left untouched (they are required to make it safely across
2736 partition boundaries). See the comments at the top of
2737 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2739 if (flag_reorder_blocks_and_partition
2740 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2741 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2742 || BB_PARTITION (a) != BB_PARTITION (b)))
2745 /* There must be exactly one edge in between the blocks. */
2746 return (EDGE_COUNT (a->succs) == 1
2747 && EDGE_SUCC (a, 0)->dest == b
2748 && EDGE_COUNT (b->preds) == 1
2750 /* Must be simple edge. */
2751 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
2752 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2753 /* If the jump insn has side effects,
2754 we can't kill the edge. */
2755 && (!JUMP_P (BB_END (a))
2756 || (reload_completed
2757 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2760 /* Merge block A and B, abort when it is not possible. */
2762 cfg_layout_merge_blocks (basic_block a, basic_block b)
2764 #ifdef ENABLE_CHECKING
2765 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2768 /* If there was a CODE_LABEL beginning B, delete it. */
2769 if (LABEL_P (BB_HEAD (b)))
2770 delete_insn (BB_HEAD (b));
2772 /* We should have fallthru edge in a, or we can do dummy redirection to get
2774 if (JUMP_P (BB_END (a)))
2775 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2776 gcc_assert (!JUMP_P (BB_END (a)));
2778 /* Possible line number notes should appear in between. */
2781 rtx first = BB_END (a), last;
2783 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2784 delete_insn_chain (NEXT_INSN (first), last);
2785 b->rbi->header = NULL;
2788 /* In the case basic blocks are not adjacent, move them around. */
2789 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2791 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2793 emit_insn_after_noloc (first, BB_END (a));
2794 /* Skip possible DELETED_LABEL insn. */
2795 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2796 first = NEXT_INSN (first);
2797 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2799 delete_insn (first);
2801 /* Otherwise just re-associate the instructions. */
2806 for (insn = BB_HEAD (b);
2807 insn != NEXT_INSN (BB_END (b));
2808 insn = NEXT_INSN (insn))
2809 set_block_for_insn (insn, a);
2811 /* Skip possible DELETED_LABEL insn. */
2812 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2813 insn = NEXT_INSN (insn);
2814 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2816 BB_END (a) = BB_END (b);
2820 /* Possible tablejumps and barriers should appear after the block. */
2823 if (!a->rbi->footer)
2824 a->rbi->footer = b->rbi->footer;
2827 rtx last = a->rbi->footer;
2829 while (NEXT_INSN (last))
2830 last = NEXT_INSN (last);
2831 NEXT_INSN (last) = b->rbi->footer;
2832 PREV_INSN (b->rbi->footer) = last;
2834 b->rbi->footer = NULL;
2838 fprintf (dump_file, "Merged blocks %d and %d.\n",
2839 a->index, b->index);
2845 cfg_layout_split_edge (edge e)
2848 basic_block new_bb =
2849 create_basic_block (e->src != ENTRY_BLOCK_PTR
2850 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2853 /* ??? This info is likely going to be out of date very soon, but we must
2854 create it to avoid getting an ICE later. */
2855 if (e->dest->global_live_at_start)
2857 new_bb->global_live_at_start = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2858 new_bb->global_live_at_end = OBSTACK_ALLOC_REG_SET (&flow_obstack);
2859 COPY_REG_SET (new_bb->global_live_at_start,
2860 e->dest->global_live_at_start);
2861 COPY_REG_SET (new_bb->global_live_at_end,
2862 e->dest->global_live_at_start);
2865 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2866 redirect_edge_and_branch_force (e, new_bb);
2871 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2874 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2878 /* Return 1 if BB ends with a call, possibly followed by some
2879 instructions that must stay with the call, 0 otherwise. */
2882 rtl_block_ends_with_call_p (basic_block bb)
2884 rtx insn = BB_END (bb);
2886 while (!CALL_P (insn)
2887 && insn != BB_HEAD (bb)
2888 && keep_with_call_p (insn))
2889 insn = PREV_INSN (insn);
2890 return (CALL_P (insn));
2893 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2896 rtl_block_ends_with_condjump_p (basic_block bb)
2898 return any_condjump_p (BB_END (bb));
2901 /* Return true if we need to add fake edge to exit.
2902 Helper function for rtl_flow_call_edges_add. */
2905 need_fake_edge_p (rtx insn)
2911 && !SIBLING_CALL_P (insn)
2912 && !find_reg_note (insn, REG_NORETURN, NULL)
2913 && !find_reg_note (insn, REG_ALWAYS_RETURN, NULL)
2914 && !CONST_OR_PURE_CALL_P (insn)))
2917 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2918 && MEM_VOLATILE_P (PATTERN (insn)))
2919 || (GET_CODE (PATTERN (insn)) == PARALLEL
2920 && asm_noperands (insn) != -1
2921 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2922 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2925 /* Add fake edges to the function exit for any non constant and non noreturn
2926 calls, volatile inline assembly in the bitmap of blocks specified by
2927 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2930 The goal is to expose cases in which entering a basic block does not imply
2931 that all subsequent instructions must be executed. */
2934 rtl_flow_call_edges_add (sbitmap blocks)
2937 int blocks_split = 0;
2938 int last_bb = last_basic_block;
2939 bool check_last_block = false;
2941 if (n_basic_blocks == 0)
2945 check_last_block = true;
2947 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2949 /* In the last basic block, before epilogue generation, there will be
2950 a fallthru edge to EXIT. Special care is required if the last insn
2951 of the last basic block is a call because make_edge folds duplicate
2952 edges, which would result in the fallthru edge also being marked
2953 fake, which would result in the fallthru edge being removed by
2954 remove_fake_edges, which would result in an invalid CFG.
2956 Moreover, we can't elide the outgoing fake edge, since the block
2957 profiler needs to take this into account in order to solve the minimal
2958 spanning tree in the case that the call doesn't return.
2960 Handle this by adding a dummy instruction in a new last basic block. */
2961 if (check_last_block)
2963 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2964 rtx insn = BB_END (bb);
2966 /* Back up past insns that must be kept in the same block as a call. */
2967 while (insn != BB_HEAD (bb)
2968 && keep_with_call_p (insn))
2969 insn = PREV_INSN (insn);
2971 if (need_fake_edge_p (insn))
2976 FOR_EACH_EDGE (e, ei, bb->succs)
2977 if (e->dest == EXIT_BLOCK_PTR)
2979 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2980 commit_edge_insertions ();
2986 /* Now add fake edges to the function exit for any non constant
2987 calls since there is no way that we can determine if they will
2990 for (i = 0; i < last_bb; i++)
2992 basic_block bb = BASIC_BLOCK (i);
2999 if (blocks && !TEST_BIT (blocks, i))
3002 for (insn = BB_END (bb); ; insn = prev_insn)
3004 prev_insn = PREV_INSN (insn);
3005 if (need_fake_edge_p (insn))
3008 rtx split_at_insn = insn;
3010 /* Don't split the block between a call and an insn that should
3011 remain in the same block as the call. */
3013 while (split_at_insn != BB_END (bb)
3014 && keep_with_call_p (NEXT_INSN (split_at_insn)))
3015 split_at_insn = NEXT_INSN (split_at_insn);
3017 /* The handling above of the final block before the epilogue
3018 should be enough to verify that there is no edge to the exit
3019 block in CFG already. Calling make_edge in such case would
3020 cause us to mark that edge as fake and remove it later. */
3022 #ifdef ENABLE_CHECKING
3023 if (split_at_insn == BB_END (bb))
3026 FOR_EACH_EDGE (e, ei, bb->succs)
3027 gcc_assert (e->dest != EXIT_BLOCK_PTR);
3031 /* Note that the following may create a new basic block
3032 and renumber the existing basic blocks. */
3033 if (split_at_insn != BB_END (bb))
3035 e = split_block (bb, split_at_insn);
3040 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3043 if (insn == BB_HEAD (bb))
3049 verify_flow_info ();
3051 return blocks_split;
3054 /* Implementation of CFG manipulation for linearized RTL. */
3055 struct cfg_hooks rtl_cfg_hooks = {
3057 rtl_verify_flow_info,
3059 rtl_create_basic_block,
3060 rtl_redirect_edge_and_branch,
3061 rtl_redirect_edge_and_branch_force,
3064 rtl_move_block_after,
3065 rtl_can_merge_blocks, /* can_merge_blocks_p */
3069 NULL, /* can_duplicate_block_p */
3070 NULL, /* duplicate_block */
3072 rtl_make_forwarder_block,
3073 rtl_tidy_fallthru_edge,
3074 rtl_block_ends_with_call_p,
3075 rtl_block_ends_with_condjump_p,
3076 rtl_flow_call_edges_add
3079 /* Implementation of CFG manipulation for cfg layout RTL, where
3080 basic block connected via fallthru edges does not have to be adjacent.
3081 This representation will hopefully become the default one in future
3082 version of the compiler. */
3084 /* We do not want to declare these functions in a header file, since they
3085 should only be used through the cfghooks interface, and we do not want to
3086 move them here since it would require also moving quite a lot of related
3088 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3089 extern basic_block cfg_layout_duplicate_bb (basic_block);
3091 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3093 rtl_verify_flow_info_1,
3095 cfg_layout_create_basic_block,
3096 cfg_layout_redirect_edge_and_branch,
3097 cfg_layout_redirect_edge_and_branch_force,
3098 cfg_layout_delete_block,
3099 cfg_layout_split_block,
3100 rtl_move_block_after,
3101 cfg_layout_can_merge_blocks_p,
3102 cfg_layout_merge_blocks,
3105 cfg_layout_can_duplicate_bb_p,
3106 cfg_layout_duplicate_bb,
3107 cfg_layout_split_edge,
3108 rtl_make_forwarder_block,
3110 rtl_block_ends_with_call_p,
3111 rtl_block_ends_with_condjump_p,
3112 rtl_flow_call_edges_add