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, 2005 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 barriers that may follow the basic block. */
383 tmp = next_nonnote_insn (end);
384 while (tmp && BARRIER_P (tmp))
387 tmp = next_nonnote_insn (end);
390 /* Selectively delete the entire chain. */
392 delete_insn_chain (insn, end);
395 /* Records the basic block struct in BLOCK_FOR_INSN for every insn. */
398 compute_bb_for_insn (void)
404 rtx end = BB_END (bb);
407 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
409 BLOCK_FOR_INSN (insn) = bb;
416 /* Release the basic_block_for_insn array. */
419 free_bb_for_insn (void)
422 for (insn = get_insns (); insn; insn = NEXT_INSN (insn))
423 if (!BARRIER_P (insn))
424 BLOCK_FOR_INSN (insn) = NULL;
427 /* Return RTX to emit after when we want to emit code on the entry of function. */
429 entry_of_function (void)
431 return (n_basic_blocks ? BB_HEAD (ENTRY_BLOCK_PTR->next_bb) : get_insns ());
434 /* Update insns block within BB. */
437 update_bb_for_insn (basic_block bb)
441 for (insn = BB_HEAD (bb); ; insn = NEXT_INSN (insn))
443 if (!BARRIER_P (insn))
444 set_block_for_insn (insn, bb);
445 if (insn == BB_END (bb))
450 /* Creates a new basic block just after basic block B by splitting
451 everything after specified instruction I. */
454 rtl_split_block (basic_block bb, void *insnp)
463 insn = first_insn_after_basic_block_note (bb);
466 insn = PREV_INSN (insn);
468 insn = get_last_insn ();
471 /* We probably should check type of the insn so that we do not create
472 inconsistent cfg. It is checked in verify_flow_info anyway, so do not
474 if (insn == BB_END (bb))
475 emit_note_after (NOTE_INSN_DELETED, insn);
477 /* Create the new basic block. */
478 new_bb = create_basic_block (NEXT_INSN (insn), BB_END (bb), bb);
479 BB_COPY_PARTITION (new_bb, bb);
482 /* Redirect the outgoing edges. */
483 new_bb->succs = bb->succs;
485 FOR_EACH_EDGE (e, ei, new_bb->succs)
488 if (bb->global_live_at_start)
490 new_bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
491 new_bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
492 COPY_REG_SET (new_bb->global_live_at_end, bb->global_live_at_end);
494 /* We now have to calculate which registers are live at the end
495 of the split basic block and at the start of the new basic
496 block. Start with those registers that are known to be live
497 at the end of the original basic block and get
498 propagate_block to determine which registers are live. */
499 COPY_REG_SET (new_bb->global_live_at_start, bb->global_live_at_end);
500 propagate_block (new_bb, new_bb->global_live_at_start, NULL, NULL, 0);
501 COPY_REG_SET (bb->global_live_at_end,
502 new_bb->global_live_at_start);
503 #ifdef HAVE_conditional_execution
504 /* In the presence of conditional execution we are not able to update
505 liveness precisely. */
506 if (reload_completed)
508 bb->flags |= BB_DIRTY;
509 new_bb->flags |= BB_DIRTY;
517 /* Blocks A and B are to be merged into a single block A. The insns
518 are already contiguous. */
521 rtl_merge_blocks (basic_block a, basic_block b)
523 rtx b_head = BB_HEAD (b), b_end = BB_END (b), a_end = BB_END (a);
524 rtx del_first = NULL_RTX, del_last = NULL_RTX;
527 /* If there was a CODE_LABEL beginning B, delete it. */
528 if (LABEL_P (b_head))
530 /* Detect basic blocks with nothing but a label. This can happen
531 in particular at the end of a function. */
535 del_first = del_last = b_head;
536 b_head = NEXT_INSN (b_head);
539 /* Delete the basic block note and handle blocks containing just that
541 if (NOTE_INSN_BASIC_BLOCK_P (b_head))
549 b_head = NEXT_INSN (b_head);
552 /* If there was a jump out of A, delete it. */
557 for (prev = PREV_INSN (a_end); ; prev = PREV_INSN (prev))
559 || NOTE_LINE_NUMBER (prev) == NOTE_INSN_BASIC_BLOCK
560 || prev == BB_HEAD (a))
566 /* If this was a conditional jump, we need to also delete
567 the insn that set cc0. */
568 if (only_sets_cc0_p (prev))
572 prev = prev_nonnote_insn (prev);
579 a_end = PREV_INSN (del_first);
581 else if (BARRIER_P (NEXT_INSN (a_end)))
582 del_first = NEXT_INSN (a_end);
584 /* Delete everything marked above as well as crap that might be
585 hanging out between the two blocks. */
587 delete_insn_chain (del_first, del_last);
589 /* Reassociate the insns of B with A. */
594 for (x = a_end; x != b_end; x = NEXT_INSN (x))
595 set_block_for_insn (x, a);
597 set_block_for_insn (b_end, a);
605 /* Return true when block A and B can be merged. */
607 rtl_can_merge_blocks (basic_block a,basic_block b)
609 /* If we are partitioning hot/cold basic blocks, we don't want to
610 mess up unconditional or indirect jumps that cross between hot
613 Basic block partitioning may result in some jumps that appear to
614 be optimizable (or blocks that appear to be mergeable), but which really
615 must be left untouched (they are required to make it safely across
616 partition boundaries). See the comments at the top of
617 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
619 if (flag_reorder_blocks_and_partition
620 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
621 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
622 || BB_PARTITION (a) != BB_PARTITION (b)))
625 /* There must be exactly one edge in between the blocks. */
626 return (EDGE_COUNT (a->succs) == 1
627 && EDGE_SUCC (a, 0)->dest == b
628 && EDGE_COUNT (b->preds) == 1
630 /* Must be simple edge. */
631 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
633 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
634 /* If the jump insn has side effects,
635 we can't kill the edge. */
636 && (!JUMP_P (BB_END (a))
638 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
641 /* Return the label in the head of basic block BLOCK. Create one if it doesn't
645 block_label (basic_block block)
647 if (block == EXIT_BLOCK_PTR)
650 if (!LABEL_P (BB_HEAD (block)))
652 BB_HEAD (block) = emit_label_before (gen_label_rtx (), BB_HEAD (block));
655 return BB_HEAD (block);
658 /* Attempt to perform edge redirection by replacing possibly complex jump
659 instruction by unconditional jump or removing jump completely. This can
660 apply only if all edges now point to the same block. The parameters and
661 return values are equivalent to redirect_edge_and_branch. */
664 try_redirect_by_replacing_jump (edge e, basic_block target, bool in_cfglayout)
666 basic_block src = e->src;
667 rtx insn = BB_END (src), kill_from;
671 /* If we are partitioning hot/cold basic blocks, we don't want to
672 mess up unconditional or indirect jumps that cross between hot
675 Basic block partitioning may result in some jumps that appear to
676 be optimizable (or blocks that appear to be mergeable), but which really
677 must be left untouched (they are required to make it safely across
678 partition boundaries). See the comments at the top of
679 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
681 if (flag_reorder_blocks_and_partition
682 && (find_reg_note (insn, REG_CROSSING_JUMP, NULL_RTX)
683 || BB_PARTITION (src) != BB_PARTITION (target)))
686 /* We can replace or remove a complex jump only when we have exactly
687 two edges. Also, if we have exactly one outgoing edge, we can
689 if (EDGE_COUNT (src->succs) >= 3
690 /* Verify that all targets will be TARGET. Specifically, the
691 edge that is not E must also go to TARGET. */
692 || (EDGE_COUNT (src->succs) == 2
693 && EDGE_SUCC (src, EDGE_SUCC (src, 0) == e)->dest != target))
696 if (!onlyjump_p (insn))
698 if ((!optimize || reload_completed) && tablejump_p (insn, NULL, NULL))
701 /* Avoid removing branch with side effects. */
702 set = single_set (insn);
703 if (!set || side_effects_p (set))
706 /* In case we zap a conditional jump, we'll need to kill
707 the cc0 setter too. */
710 if (reg_mentioned_p (cc0_rtx, PATTERN (insn)))
711 kill_from = PREV_INSN (insn);
714 /* See if we can create the fallthru edge. */
715 if (in_cfglayout || can_fallthru (src, target))
718 fprintf (dump_file, "Removing jump %i.\n", INSN_UID (insn));
721 /* Selectively unlink whole insn chain. */
724 rtx insn = src->rbi->footer;
726 delete_insn_chain (kill_from, BB_END (src));
728 /* Remove barriers but keep jumptables. */
731 if (BARRIER_P (insn))
733 if (PREV_INSN (insn))
734 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
736 src->rbi->footer = NEXT_INSN (insn);
737 if (NEXT_INSN (insn))
738 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
742 insn = NEXT_INSN (insn);
746 delete_insn_chain (kill_from, PREV_INSN (BB_HEAD (target)));
749 /* If this already is simplejump, redirect it. */
750 else if (simplejump_p (insn))
752 if (e->dest == target)
755 fprintf (dump_file, "Redirecting jump %i from %i to %i.\n",
756 INSN_UID (insn), e->dest->index, target->index);
757 if (!redirect_jump (insn, block_label (target), 0))
759 gcc_assert (target == EXIT_BLOCK_PTR);
764 /* Cannot do anything for target exit block. */
765 else if (target == EXIT_BLOCK_PTR)
768 /* Or replace possibly complicated jump insn by simple jump insn. */
771 rtx target_label = block_label (target);
772 rtx barrier, label, table;
774 emit_jump_insn_after_noloc (gen_jump (target_label), insn);
775 JUMP_LABEL (BB_END (src)) = target_label;
776 LABEL_NUSES (target_label)++;
778 fprintf (dump_file, "Replacing insn %i by jump %i\n",
779 INSN_UID (insn), INSN_UID (BB_END (src)));
782 delete_insn_chain (kill_from, insn);
784 /* Recognize a tablejump that we are converting to a
785 simple jump and remove its associated CODE_LABEL
786 and ADDR_VEC or ADDR_DIFF_VEC. */
787 if (tablejump_p (insn, &label, &table))
788 delete_insn_chain (label, table);
790 barrier = next_nonnote_insn (BB_END (src));
791 if (!barrier || !BARRIER_P (barrier))
792 emit_barrier_after (BB_END (src));
795 if (barrier != NEXT_INSN (BB_END (src)))
797 /* Move the jump before barrier so that the notes
798 which originally were or were created before jump table are
799 inside the basic block. */
800 rtx new_insn = BB_END (src);
803 for (tmp = NEXT_INSN (BB_END (src)); tmp != barrier;
804 tmp = NEXT_INSN (tmp))
805 set_block_for_insn (tmp, src);
807 NEXT_INSN (PREV_INSN (new_insn)) = NEXT_INSN (new_insn);
808 PREV_INSN (NEXT_INSN (new_insn)) = PREV_INSN (new_insn);
810 NEXT_INSN (new_insn) = barrier;
811 NEXT_INSN (PREV_INSN (barrier)) = new_insn;
813 PREV_INSN (new_insn) = PREV_INSN (barrier);
814 PREV_INSN (barrier) = new_insn;
819 /* Keep only one edge out and set proper flags. */
820 while (EDGE_COUNT (src->succs) > 1)
823 e = EDGE_SUCC (src, 0);
825 e->flags = EDGE_FALLTHRU;
829 e->probability = REG_BR_PROB_BASE;
830 e->count = src->count;
832 /* We don't want a block to end on a line-number note since that has
833 the potential of changing the code between -g and not -g. */
834 while (NOTE_P (BB_END (e->src))
835 && NOTE_LINE_NUMBER (BB_END (e->src)) >= 0)
836 delete_insn (BB_END (e->src));
838 if (e->dest != target)
839 redirect_edge_succ (e, target);
844 /* Return last loop_beg note appearing after INSN, before start of next
845 basic block. Return INSN if there are no such notes.
847 When emitting jump to redirect a fallthru edge, it should always appear
848 after the LOOP_BEG notes, as loop optimizer expect loop to either start by
849 fallthru edge or jump following the LOOP_BEG note jumping to the loop exit
853 last_loop_beg_note (rtx insn)
857 for (insn = NEXT_INSN (insn); insn && NOTE_P (insn)
858 && NOTE_LINE_NUMBER (insn) != NOTE_INSN_BASIC_BLOCK;
859 insn = NEXT_INSN (insn))
860 if (NOTE_LINE_NUMBER (insn) == NOTE_INSN_LOOP_BEG)
866 /* Redirect edge representing branch of (un)conditional jump or tablejump,
869 redirect_branch_edge (edge e, basic_block target)
872 rtx old_label = BB_HEAD (e->dest);
873 basic_block src = e->src;
874 rtx insn = BB_END (src);
876 /* We can only redirect non-fallthru edges of jump insn. */
877 if (e->flags & EDGE_FALLTHRU)
879 else if (!JUMP_P (insn))
882 /* Recognize a tablejump and adjust all matching cases. */
883 if (tablejump_p (insn, NULL, &tmp))
887 rtx new_label = block_label (target);
889 if (target == EXIT_BLOCK_PTR)
891 if (GET_CODE (PATTERN (tmp)) == ADDR_VEC)
892 vec = XVEC (PATTERN (tmp), 0);
894 vec = XVEC (PATTERN (tmp), 1);
896 for (j = GET_NUM_ELEM (vec) - 1; j >= 0; --j)
897 if (XEXP (RTVEC_ELT (vec, j), 0) == old_label)
899 RTVEC_ELT (vec, j) = gen_rtx_LABEL_REF (Pmode, new_label);
900 --LABEL_NUSES (old_label);
901 ++LABEL_NUSES (new_label);
904 /* Handle casesi dispatch insns. */
905 if ((tmp = single_set (insn)) != NULL
906 && SET_DEST (tmp) == pc_rtx
907 && GET_CODE (SET_SRC (tmp)) == IF_THEN_ELSE
908 && GET_CODE (XEXP (SET_SRC (tmp), 2)) == LABEL_REF
909 && XEXP (XEXP (SET_SRC (tmp), 2), 0) == old_label)
911 XEXP (SET_SRC (tmp), 2) = gen_rtx_LABEL_REF (VOIDmode,
913 --LABEL_NUSES (old_label);
914 ++LABEL_NUSES (new_label);
919 /* ?? We may play the games with moving the named labels from
920 one basic block to the other in case only one computed_jump is
922 if (computed_jump_p (insn)
923 /* A return instruction can't be redirected. */
924 || returnjump_p (insn))
927 /* If the insn doesn't go where we think, we're confused. */
928 gcc_assert (JUMP_LABEL (insn) == old_label);
930 /* If the substitution doesn't succeed, die. This can happen
931 if the back end emitted unrecognizable instructions or if
932 target is exit block on some arches. */
933 if (!redirect_jump (insn, block_label (target), 0))
935 gcc_assert (target == EXIT_BLOCK_PTR);
941 fprintf (dump_file, "Edge %i->%i redirected to %i\n",
942 e->src->index, e->dest->index, target->index);
944 if (e->dest != target)
945 e = redirect_edge_succ_nodup (e, target);
949 /* Attempt to change code to redirect edge E to TARGET. Don't do that on
950 expense of adding new instructions or reordering basic blocks.
952 Function can be also called with edge destination equivalent to the TARGET.
953 Then it should try the simplifications and do nothing if none is possible.
955 Return edge representing the branch if transformation succeeded. Return NULL
957 We still return NULL in case E already destinated TARGET and we didn't
958 managed to simplify instruction stream. */
961 rtl_redirect_edge_and_branch (edge e, basic_block target)
964 basic_block src = e->src;
966 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
969 if (e->dest == target)
972 if ((ret = try_redirect_by_replacing_jump (e, target, false)) != NULL)
974 src->flags |= BB_DIRTY;
978 ret = redirect_branch_edge (e, target);
982 src->flags |= BB_DIRTY;
986 /* Like force_nonfallthru below, but additionally performs redirection
987 Used by redirect_edge_and_branch_force. */
990 force_nonfallthru_and_redirect (edge e, basic_block target)
992 basic_block jump_block, new_bb = NULL, src = e->src;
995 int abnormal_edge_flags = 0;
997 /* In the case the last instruction is conditional jump to the next
998 instruction, first redirect the jump itself and then continue
999 by creating a basic block afterwards to redirect fallthru edge. */
1000 if (e->src != ENTRY_BLOCK_PTR && e->dest != EXIT_BLOCK_PTR
1001 && any_condjump_p (BB_END (e->src))
1002 /* When called from cfglayout, fallthru edges do not
1003 necessarily go to the next block. */
1004 && e->src->next_bb == e->dest
1005 && JUMP_LABEL (BB_END (e->src)) == BB_HEAD (e->dest))
1008 edge b = unchecked_make_edge (e->src, target, 0);
1011 redirected = redirect_jump (BB_END (e->src), block_label (target), 0);
1012 gcc_assert (redirected);
1014 note = find_reg_note (BB_END (e->src), REG_BR_PROB, NULL_RTX);
1017 int prob = INTVAL (XEXP (note, 0));
1019 b->probability = prob;
1020 b->count = e->count * prob / REG_BR_PROB_BASE;
1021 e->probability -= e->probability;
1022 e->count -= b->count;
1023 if (e->probability < 0)
1030 if (e->flags & EDGE_ABNORMAL)
1032 /* Irritating special case - fallthru edge to the same block as abnormal
1034 We can't redirect abnormal edge, but we still can split the fallthru
1035 one and create separate abnormal edge to original destination.
1036 This allows bb-reorder to make such edge non-fallthru. */
1037 gcc_assert (e->dest == target);
1038 abnormal_edge_flags = e->flags & ~(EDGE_FALLTHRU | EDGE_CAN_FALLTHRU);
1039 e->flags &= EDGE_FALLTHRU | EDGE_CAN_FALLTHRU;
1043 gcc_assert (e->flags & EDGE_FALLTHRU);
1044 if (e->src == ENTRY_BLOCK_PTR)
1046 /* We can't redirect the entry block. Create an empty block
1047 at the start of the function which we use to add the new
1053 basic_block bb = create_basic_block (BB_HEAD (e->dest), NULL, ENTRY_BLOCK_PTR);
1055 /* Change the existing edge's source to be the new block, and add
1056 a new edge from the entry block to the new block. */
1058 for (ei = ei_start (ENTRY_BLOCK_PTR->succs); (tmp = ei_safe_edge (ei)); )
1062 VEC_unordered_remove (edge, ENTRY_BLOCK_PTR->succs, ei.index);
1072 VEC_safe_push (edge, bb->succs, e);
1073 make_single_succ_edge (ENTRY_BLOCK_PTR, bb, EDGE_FALLTHRU);
1077 if (EDGE_COUNT (e->src->succs) >= 2 || abnormal_edge_flags)
1079 /* Create the new structures. */
1081 /* If the old block ended with a tablejump, skip its table
1082 by searching forward from there. Otherwise start searching
1083 forward from the last instruction of the old block. */
1084 if (!tablejump_p (BB_END (e->src), NULL, ¬e))
1085 note = BB_END (e->src);
1087 /* Position the new block correctly relative to loop notes. */
1088 note = last_loop_beg_note (note);
1089 note = NEXT_INSN (note);
1091 jump_block = create_basic_block (note, NULL, e->src);
1092 jump_block->count = e->count;
1093 jump_block->frequency = EDGE_FREQUENCY (e);
1094 jump_block->loop_depth = target->loop_depth;
1096 if (target->global_live_at_start)
1098 jump_block->global_live_at_start = ALLOC_REG_SET (®_obstack);
1099 jump_block->global_live_at_end = ALLOC_REG_SET (®_obstack);
1100 COPY_REG_SET (jump_block->global_live_at_start,
1101 target->global_live_at_start);
1102 COPY_REG_SET (jump_block->global_live_at_end,
1103 target->global_live_at_start);
1106 /* Make sure new block ends up in correct hot/cold section. */
1108 BB_COPY_PARTITION (jump_block, e->src);
1109 if (flag_reorder_blocks_and_partition
1110 && targetm.have_named_sections)
1112 if (BB_PARTITION (jump_block) == BB_COLD_PARTITION)
1114 rtx bb_note, new_note;
1115 for (bb_note = BB_HEAD (jump_block);
1116 bb_note && bb_note != NEXT_INSN (BB_END (jump_block));
1117 bb_note = NEXT_INSN (bb_note))
1118 if (NOTE_P (bb_note)
1119 && NOTE_LINE_NUMBER (bb_note) == NOTE_INSN_BASIC_BLOCK)
1121 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1123 NOTE_BASIC_BLOCK (new_note) = jump_block;
1125 if (JUMP_P (BB_END (jump_block))
1126 && !any_condjump_p (BB_END (jump_block))
1127 && (EDGE_SUCC (jump_block, 0)->flags & EDGE_CROSSING))
1128 REG_NOTES (BB_END (jump_block)) = gen_rtx_EXPR_LIST
1129 (REG_CROSSING_JUMP, NULL_RTX,
1130 REG_NOTES (BB_END (jump_block)));
1134 new_edge = make_edge (e->src, jump_block, EDGE_FALLTHRU);
1135 new_edge->probability = e->probability;
1136 new_edge->count = e->count;
1138 /* Redirect old edge. */
1139 redirect_edge_pred (e, jump_block);
1140 e->probability = REG_BR_PROB_BASE;
1142 new_bb = jump_block;
1145 jump_block = e->src;
1147 e->flags &= ~EDGE_FALLTHRU;
1148 if (target == EXIT_BLOCK_PTR)
1151 emit_jump_insn_after_noloc (gen_return (), BB_END (jump_block));
1158 rtx label = block_label (target);
1159 emit_jump_insn_after_noloc (gen_jump (label), BB_END (jump_block));
1160 JUMP_LABEL (BB_END (jump_block)) = label;
1161 LABEL_NUSES (label)++;
1164 emit_barrier_after (BB_END (jump_block));
1165 redirect_edge_succ_nodup (e, target);
1167 if (abnormal_edge_flags)
1168 make_edge (src, target, abnormal_edge_flags);
1173 /* Edge E is assumed to be fallthru edge. Emit needed jump instruction
1174 (and possibly create new basic block) to make edge non-fallthru.
1175 Return newly created BB or NULL if none. */
1178 force_nonfallthru (edge e)
1180 return force_nonfallthru_and_redirect (e, e->dest);
1183 /* Redirect edge even at the expense of creating new jump insn or
1184 basic block. Return new basic block if created, NULL otherwise.
1185 Abort if conversion is impossible. */
1188 rtl_redirect_edge_and_branch_force (edge e, basic_block target)
1190 if (redirect_edge_and_branch (e, target)
1191 || e->dest == target)
1194 /* In case the edge redirection failed, try to force it to be non-fallthru
1195 and redirect newly created simplejump. */
1196 return force_nonfallthru_and_redirect (e, target);
1199 /* The given edge should potentially be a fallthru edge. If that is in
1200 fact true, delete the jump and barriers that are in the way. */
1203 rtl_tidy_fallthru_edge (edge e)
1206 basic_block b = e->src, c = b->next_bb;
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_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);
1474 /* Mark all hard registers as killed. Register allocator/reload cannot
1475 cope with the situation when life range of hard register spans operation
1476 for that the appropriate register is needed, i.e. it would be unsafe to
1477 extend the life ranges of hard registers. */
1478 for (regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
1479 if (!fixed_regs[regno]
1480 && !REGNO_PTR_FRAME_P (regno))
1481 SET_REGNO_REG_SET (killed, regno);
1483 bitmap_and_into (killed, e->dest->global_live_at_start);
1485 EXECUTE_IF_SET_IN_REG_SET (killed, 0, regno, rsi)
1487 mode = regno < FIRST_PSEUDO_REGISTER
1488 ? reg_raw_mode[regno]
1489 : GET_MODE (regno_reg_rtx[regno]);
1490 if (mode == VOIDmode)
1493 if (noccmode && mode == CCmode)
1496 save_regs = alloc_EXPR_LIST (0,
1499 gen_raw_REG (mode, regno)),
1508 for (x = save_regs; x; x = XEXP (x, 1))
1510 from = XEXP (XEXP (x, 0), 1);
1511 to = XEXP (XEXP (x, 0), 0);
1512 emit_move_insn (to, from);
1515 for (x = save_regs; x; x = XEXP (x, 1))
1517 from = XEXP (XEXP (x, 0), 0);
1518 to = XEXP (XEXP (x, 0), 1);
1519 emit_move_insn (to, from);
1521 insn = get_insns ();
1523 free_EXPR_LIST_list (&save_regs);
1525 insert_insn_on_edge (insn, e);
1527 FREE_REG_SET (killed);
1532 /* Update the CFG for the instructions queued on edge E. */
1535 commit_one_edge_insertion (edge e, int watch_calls)
1537 rtx before = NULL_RTX, after = NULL_RTX, insns, tmp, last;
1538 basic_block bb = NULL;
1540 /* Pull the insns off the edge now since the edge might go away. */
1542 e->insns.r = NULL_RTX;
1544 /* Special case -- avoid inserting code between call and storing
1545 its return value. */
1546 if (watch_calls && (e->flags & EDGE_FALLTHRU)
1547 && EDGE_COUNT (e->dest->preds) == 1
1548 && e->src != ENTRY_BLOCK_PTR
1549 && CALL_P (BB_END (e->src)))
1551 rtx next = next_nonnote_insn (BB_END (e->src));
1553 after = BB_HEAD (e->dest);
1554 /* The first insn after the call may be a stack pop, skip it. */
1556 && keep_with_call_p (next))
1559 next = next_nonnote_insn (next);
1563 if (!before && !after)
1565 /* Figure out where to put these things. If the destination has
1566 one predecessor, insert there. Except for the exit block. */
1567 if (EDGE_COUNT (e->dest->preds) == 1 && e->dest != EXIT_BLOCK_PTR)
1571 /* Get the location correct wrt a code label, and "nice" wrt
1572 a basic block note, and before everything else. */
1575 tmp = NEXT_INSN (tmp);
1576 if (NOTE_INSN_BASIC_BLOCK_P (tmp))
1577 tmp = NEXT_INSN (tmp);
1580 && NOTE_LINE_NUMBER (tmp) == NOTE_INSN_UNLIKELY_EXECUTED_CODE)
1581 tmp = NEXT_INSN (tmp);
1582 if (tmp == BB_HEAD (bb))
1585 after = PREV_INSN (tmp);
1587 after = get_last_insn ();
1590 /* If the source has one successor and the edge is not abnormal,
1591 insert there. Except for the entry block. */
1592 else if ((e->flags & EDGE_ABNORMAL) == 0
1593 && EDGE_COUNT (e->src->succs) == 1
1594 && e->src != ENTRY_BLOCK_PTR)
1598 /* It is possible to have a non-simple jump here. Consider a target
1599 where some forms of unconditional jumps clobber a register. This
1600 happens on the fr30 for example.
1602 We know this block has a single successor, so we can just emit
1603 the queued insns before the jump. */
1604 if (JUMP_P (BB_END (bb)))
1605 for (before = BB_END (bb);
1606 NOTE_P (PREV_INSN (before))
1607 && NOTE_LINE_NUMBER (PREV_INSN (before)) ==
1608 NOTE_INSN_LOOP_BEG; before = PREV_INSN (before))
1612 /* We'd better be fallthru, or we've lost track of
1614 gcc_assert (e->flags & EDGE_FALLTHRU);
1616 after = BB_END (bb);
1619 /* Otherwise we must split the edge. */
1622 bb = split_edge (e);
1623 after = BB_END (bb);
1625 if (flag_reorder_blocks_and_partition
1626 && targetm.have_named_sections
1627 && e->src != ENTRY_BLOCK_PTR
1628 && BB_PARTITION (e->src) == BB_COLD_PARTITION
1629 && !(e->flags & EDGE_CROSSING))
1631 rtx bb_note, new_note, cur_insn;
1634 for (cur_insn = BB_HEAD (bb); cur_insn != NEXT_INSN (BB_END (bb));
1635 cur_insn = NEXT_INSN (cur_insn))
1636 if (NOTE_P (cur_insn)
1637 && NOTE_LINE_NUMBER (cur_insn) == NOTE_INSN_BASIC_BLOCK)
1643 new_note = emit_note_after (NOTE_INSN_UNLIKELY_EXECUTED_CODE,
1645 NOTE_BASIC_BLOCK (new_note) = bb;
1646 if (JUMP_P (BB_END (bb))
1647 && !any_condjump_p (BB_END (bb))
1648 && (EDGE_SUCC (bb, 0)->flags & EDGE_CROSSING))
1649 REG_NOTES (BB_END (bb)) = gen_rtx_EXPR_LIST
1650 (REG_CROSSING_JUMP, NULL_RTX, REG_NOTES (BB_END (bb)));
1651 if (after == bb_note)
1657 /* Now that we've found the spot, do the insertion. */
1661 emit_insn_before_noloc (insns, before);
1662 last = prev_nonnote_insn (before);
1665 last = emit_insn_after_noloc (insns, after);
1667 if (returnjump_p (last))
1669 /* ??? Remove all outgoing edges from BB and add one for EXIT.
1670 This is not currently a problem because this only happens
1671 for the (single) epilogue, which already has a fallthru edge
1674 e = EDGE_SUCC (bb, 0);
1675 gcc_assert (e->dest == EXIT_BLOCK_PTR
1676 && EDGE_COUNT (bb->succs) == 1 && (e->flags & EDGE_FALLTHRU));
1678 e->flags &= ~EDGE_FALLTHRU;
1679 emit_barrier_after (last);
1682 delete_insn (before);
1685 gcc_assert (!JUMP_P (last));
1687 /* Mark the basic block for find_many_sub_basic_blocks. */
1691 /* Update the CFG for all queued instructions. */
1694 commit_edge_insertions (void)
1698 bool changed = false;
1700 #ifdef ENABLE_CHECKING
1701 verify_flow_info ();
1704 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1709 FOR_EACH_EDGE (e, ei, bb->succs)
1713 commit_one_edge_insertion (e, false);
1720 blocks = sbitmap_alloc (last_basic_block);
1721 sbitmap_zero (blocks);
1725 SET_BIT (blocks, bb->index);
1726 /* Check for forgotten bb->aux values before commit_edge_insertions
1728 gcc_assert (bb->aux == &bb->aux);
1731 find_many_sub_basic_blocks (blocks);
1732 sbitmap_free (blocks);
1735 /* Update the CFG for all queued instructions, taking special care of inserting
1736 code on edges between call and storing its return value. */
1739 commit_edge_insertions_watch_calls (void)
1743 bool changed = false;
1745 #ifdef ENABLE_CHECKING
1746 verify_flow_info ();
1749 FOR_BB_BETWEEN (bb, ENTRY_BLOCK_PTR, EXIT_BLOCK_PTR, next_bb)
1754 FOR_EACH_EDGE (e, ei, bb->succs)
1758 commit_one_edge_insertion (e, true);
1765 blocks = sbitmap_alloc (last_basic_block);
1766 sbitmap_zero (blocks);
1770 SET_BIT (blocks, bb->index);
1771 /* Check for forgotten bb->aux values before commit_edge_insertions
1773 gcc_assert (bb->aux == &bb->aux);
1776 find_many_sub_basic_blocks (blocks);
1777 sbitmap_free (blocks);
1780 /* Print out RTL-specific basic block information (live information
1781 at start and end). */
1784 rtl_dump_bb (basic_block bb, FILE *outf, int indent)
1790 s_indent = alloca ((size_t) indent + 1);
1791 memset (s_indent, ' ', (size_t) indent);
1792 s_indent[indent] = '\0';
1794 fprintf (outf, ";;%s Registers live at start: ", s_indent);
1795 dump_regset (bb->global_live_at_start, outf);
1798 for (insn = BB_HEAD (bb), last = NEXT_INSN (BB_END (bb)); insn != last;
1799 insn = NEXT_INSN (insn))
1800 print_rtl_single (outf, insn);
1802 fprintf (outf, ";;%s Registers live at end: ", s_indent);
1803 dump_regset (bb->global_live_at_end, outf);
1807 /* Like print_rtl, but also print out live information for the start of each
1811 print_rtl_with_bb (FILE *outf, rtx rtx_first)
1816 fprintf (outf, "(nil)\n");
1819 enum bb_state { NOT_IN_BB, IN_ONE_BB, IN_MULTIPLE_BB };
1820 int max_uid = get_max_uid ();
1821 basic_block *start = xcalloc (max_uid, sizeof (basic_block));
1822 basic_block *end = xcalloc (max_uid, sizeof (basic_block));
1823 enum bb_state *in_bb_p = xcalloc (max_uid, sizeof (enum bb_state));
1827 FOR_EACH_BB_REVERSE (bb)
1831 start[INSN_UID (BB_HEAD (bb))] = bb;
1832 end[INSN_UID (BB_END (bb))] = bb;
1833 for (x = BB_HEAD (bb); x != NULL_RTX; x = NEXT_INSN (x))
1835 enum bb_state state = IN_MULTIPLE_BB;
1837 if (in_bb_p[INSN_UID (x)] == NOT_IN_BB)
1839 in_bb_p[INSN_UID (x)] = state;
1841 if (x == BB_END (bb))
1846 for (tmp_rtx = rtx_first; NULL != tmp_rtx; tmp_rtx = NEXT_INSN (tmp_rtx))
1850 if ((bb = start[INSN_UID (tmp_rtx)]) != NULL)
1852 fprintf (outf, ";; Start of basic block %d, registers live:",
1854 dump_regset (bb->global_live_at_start, outf);
1858 if (in_bb_p[INSN_UID (tmp_rtx)] == NOT_IN_BB
1859 && !NOTE_P (tmp_rtx)
1860 && !BARRIER_P (tmp_rtx))
1861 fprintf (outf, ";; Insn is not within a basic block\n");
1862 else if (in_bb_p[INSN_UID (tmp_rtx)] == IN_MULTIPLE_BB)
1863 fprintf (outf, ";; Insn is in multiple basic blocks\n");
1865 did_output = print_rtl_single (outf, tmp_rtx);
1867 if ((bb = end[INSN_UID (tmp_rtx)]) != NULL)
1869 fprintf (outf, ";; End of basic block %d, registers live:\n",
1871 dump_regset (bb->global_live_at_end, outf);
1884 if (current_function_epilogue_delay_list != 0)
1886 fprintf (outf, "\n;; Insns in epilogue delay list:\n\n");
1887 for (tmp_rtx = current_function_epilogue_delay_list; tmp_rtx != 0;
1888 tmp_rtx = XEXP (tmp_rtx, 1))
1889 print_rtl_single (outf, XEXP (tmp_rtx, 0));
1894 update_br_prob_note (basic_block bb)
1897 if (!JUMP_P (BB_END (bb)))
1899 note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX);
1900 if (!note || INTVAL (XEXP (note, 0)) == BRANCH_EDGE (bb)->probability)
1902 XEXP (note, 0) = GEN_INT (BRANCH_EDGE (bb)->probability);
1905 /* Verify the CFG and RTL consistency common for both underlying RTL and
1908 Currently it does following checks:
1910 - test head/end pointers
1911 - overlapping of basic blocks
1912 - headers of basic blocks (the NOTE_INSN_BASIC_BLOCK note)
1913 - tails of basic blocks (ensure that boundary is necessary)
1914 - scans body of the basic block for JUMP_INSN, CODE_LABEL
1915 and NOTE_INSN_BASIC_BLOCK
1916 - verify that no fall_thru edge crosses hot/cold partition boundaries
1918 In future it can be extended check a lot of other stuff as well
1919 (reachability of basic blocks, life information, etc. etc.). */
1922 rtl_verify_flow_info_1 (void)
1924 const int max_uid = get_max_uid ();
1925 rtx last_head = get_last_insn ();
1926 basic_block *bb_info;
1931 bb_info = xcalloc (max_uid, sizeof (basic_block));
1933 FOR_EACH_BB_REVERSE (bb)
1935 rtx head = BB_HEAD (bb);
1936 rtx end = BB_END (bb);
1938 /* Verify the end of the basic block is in the INSN chain. */
1939 for (x = last_head; x != NULL_RTX; x = PREV_INSN (x))
1945 error ("end insn %d for block %d not found in the insn stream",
1946 INSN_UID (end), bb->index);
1950 /* Work backwards from the end to the head of the basic block
1951 to verify the head is in the RTL chain. */
1952 for (; x != NULL_RTX; x = PREV_INSN (x))
1954 /* While walking over the insn chain, verify insns appear
1955 in only one basic block and initialize the BB_INFO array
1956 used by other passes. */
1957 if (bb_info[INSN_UID (x)] != NULL)
1959 error ("insn %d is in multiple basic blocks (%d and %d)",
1960 INSN_UID (x), bb->index, bb_info[INSN_UID (x)]->index);
1964 bb_info[INSN_UID (x)] = bb;
1971 error ("head insn %d for block %d not found in the insn stream",
1972 INSN_UID (head), bb->index);
1979 /* Now check the basic blocks (boundaries etc.) */
1980 FOR_EACH_BB_REVERSE (bb)
1982 int n_fallthru = 0, n_eh = 0, n_call = 0, n_abnormal = 0, n_branch = 0;
1983 edge e, fallthru = NULL;
1987 if (JUMP_P (BB_END (bb))
1988 && (note = find_reg_note (BB_END (bb), REG_BR_PROB, NULL_RTX))
1989 && EDGE_COUNT (bb->succs) >= 2
1990 && any_condjump_p (BB_END (bb)))
1992 if (INTVAL (XEXP (note, 0)) != BRANCH_EDGE (bb)->probability
1993 && profile_status != PROFILE_ABSENT)
1995 error ("verify_flow_info: REG_BR_PROB does not match cfg %wi %i",
1996 INTVAL (XEXP (note, 0)), BRANCH_EDGE (bb)->probability);
2000 FOR_EACH_EDGE (e, ei, bb->succs)
2002 if (e->flags & EDGE_FALLTHRU)
2004 n_fallthru++, fallthru = e;
2005 if ((e->flags & EDGE_CROSSING)
2006 || (BB_PARTITION (e->src) != BB_PARTITION (e->dest)
2007 && e->src != ENTRY_BLOCK_PTR
2008 && e->dest != EXIT_BLOCK_PTR))
2010 error ("Fallthru edge crosses section boundary (bb %i)",
2016 if ((e->flags & ~(EDGE_DFS_BACK
2018 | EDGE_IRREDUCIBLE_LOOP
2020 | EDGE_CROSSING)) == 0)
2023 if (e->flags & EDGE_ABNORMAL_CALL)
2026 if (e->flags & EDGE_EH)
2028 else if (e->flags & EDGE_ABNORMAL)
2032 if (n_eh && GET_CODE (PATTERN (BB_END (bb))) != RESX
2033 && !find_reg_note (BB_END (bb), REG_EH_REGION, NULL_RTX))
2035 error ("Missing REG_EH_REGION note in the end of bb %i", bb->index);
2039 && (!JUMP_P (BB_END (bb))
2040 || (n_branch > 1 && (any_uncondjump_p (BB_END (bb))
2041 || any_condjump_p (BB_END (bb))))))
2043 error ("Too many outgoing branch edges from bb %i", bb->index);
2046 if (n_fallthru && any_uncondjump_p (BB_END (bb)))
2048 error ("Fallthru edge after unconditional jump %i", bb->index);
2051 if (n_branch != 1 && any_uncondjump_p (BB_END (bb)))
2053 error ("Wrong amount of branch edges after unconditional jump %i", bb->index);
2056 if (n_branch != 1 && any_condjump_p (BB_END (bb))
2057 && JUMP_LABEL (BB_END (bb)) != BB_HEAD (fallthru->dest))
2059 error ("Wrong amount of branch edges after conditional jump %i", bb->index);
2062 if (n_call && !CALL_P (BB_END (bb)))
2064 error ("Call edges for non-call insn in bb %i", bb->index);
2068 && (!CALL_P (BB_END (bb)) && n_call != n_abnormal)
2069 && (!JUMP_P (BB_END (bb))
2070 || any_condjump_p (BB_END (bb))
2071 || any_uncondjump_p (BB_END (bb))))
2073 error ("Abnormal edges for no purpose in bb %i", bb->index);
2077 for (x = BB_HEAD (bb); x != NEXT_INSN (BB_END (bb)); x = NEXT_INSN (x))
2078 /* We may have a barrier inside a basic block before dead code
2079 elimination. There is no BLOCK_FOR_INSN field in a barrier. */
2080 if (!BARRIER_P (x) && BLOCK_FOR_INSN (x) != bb)
2083 if (! BLOCK_FOR_INSN (x))
2085 ("insn %d inside basic block %d but block_for_insn is NULL",
2086 INSN_UID (x), bb->index);
2089 ("insn %d inside basic block %d but block_for_insn is %i",
2090 INSN_UID (x), bb->index, BLOCK_FOR_INSN (x)->index);
2095 /* OK pointers are correct. Now check the header of basic
2096 block. It ought to contain optional CODE_LABEL followed
2097 by NOTE_BASIC_BLOCK. */
2101 if (BB_END (bb) == x)
2103 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2111 if (!NOTE_INSN_BASIC_BLOCK_P (x) || NOTE_BASIC_BLOCK (x) != bb)
2113 error ("NOTE_INSN_BASIC_BLOCK is missing for block %d",
2118 if (BB_END (bb) == x)
2119 /* Do checks for empty blocks here. */
2122 for (x = NEXT_INSN (x); x; x = NEXT_INSN (x))
2124 if (NOTE_INSN_BASIC_BLOCK_P (x))
2126 error ("NOTE_INSN_BASIC_BLOCK %d in middle of basic block %d",
2127 INSN_UID (x), bb->index);
2131 if (x == BB_END (bb))
2134 if (control_flow_insn_p (x))
2136 error ("in basic block %d:", bb->index);
2137 fatal_insn ("flow control insn inside a basic block", x);
2147 /* Verify the CFG and RTL consistency common for both underlying RTL and
2150 Currently it does following checks:
2151 - all checks of rtl_verify_flow_info_1
2152 - check that all insns are in the basic blocks
2153 (except the switch handling code, barriers and notes)
2154 - check that all returns are followed by barriers
2155 - check that all fallthru edge points to the adjacent blocks. */
2157 rtl_verify_flow_info (void)
2160 int err = rtl_verify_flow_info_1 ();
2163 const rtx rtx_first = get_insns ();
2164 basic_block last_bb_seen = ENTRY_BLOCK_PTR, curr_bb = NULL;
2166 FOR_EACH_BB_REVERSE (bb)
2171 FOR_EACH_EDGE (e, ei, bb->succs)
2172 if (e->flags & EDGE_FALLTHRU)
2178 /* Ensure existence of barrier in BB with no fallthru edges. */
2179 for (insn = BB_END (bb); !insn || !BARRIER_P (insn);
2180 insn = NEXT_INSN (insn))
2183 && NOTE_LINE_NUMBER (insn) == NOTE_INSN_BASIC_BLOCK))
2185 error ("missing barrier after block %i", bb->index);
2190 else if (e->src != ENTRY_BLOCK_PTR
2191 && e->dest != EXIT_BLOCK_PTR)
2195 if (e->src->next_bb != e->dest)
2198 ("verify_flow_info: Incorrect blocks for fallthru %i->%i",
2199 e->src->index, e->dest->index);
2203 for (insn = NEXT_INSN (BB_END (e->src)); insn != BB_HEAD (e->dest);
2204 insn = NEXT_INSN (insn))
2205 if (BARRIER_P (insn) || INSN_P (insn))
2207 error ("verify_flow_info: Incorrect fallthru %i->%i",
2208 e->src->index, e->dest->index);
2209 fatal_insn ("wrong insn in the fallthru edge", insn);
2216 last_bb_seen = ENTRY_BLOCK_PTR;
2218 for (x = rtx_first; x; x = NEXT_INSN (x))
2220 if (NOTE_INSN_BASIC_BLOCK_P (x))
2222 bb = NOTE_BASIC_BLOCK (x);
2225 if (bb != last_bb_seen->next_bb)
2226 internal_error ("basic blocks not laid down consecutively");
2228 curr_bb = last_bb_seen = bb;
2233 switch (GET_CODE (x))
2240 /* An addr_vec is placed outside any basic block. */
2242 && JUMP_P (NEXT_INSN (x))
2243 && (GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_DIFF_VEC
2244 || GET_CODE (PATTERN (NEXT_INSN (x))) == ADDR_VEC))
2247 /* But in any case, non-deletable labels can appear anywhere. */
2251 fatal_insn ("insn outside basic block", x);
2256 && returnjump_p (x) && ! condjump_p (x)
2257 && ! (NEXT_INSN (x) && BARRIER_P (NEXT_INSN (x))))
2258 fatal_insn ("return not followed by barrier", x);
2259 if (curr_bb && x == BB_END (curr_bb))
2263 if (num_bb_notes != n_basic_blocks)
2265 ("number of bb notes in insn chain (%d) != n_basic_blocks (%d)",
2266 num_bb_notes, n_basic_blocks);
2271 /* Assume that the preceding pass has possibly eliminated jump instructions
2272 or converted the unconditional jumps. Eliminate the edges from CFG.
2273 Return true if any edges are eliminated. */
2276 purge_dead_edges (basic_block bb)
2279 rtx insn = BB_END (bb), note;
2280 bool purged = false;
2284 /* If this instruction cannot trap, remove REG_EH_REGION notes. */
2285 if (NONJUMP_INSN_P (insn)
2286 && (note = find_reg_note (insn, REG_EH_REGION, NULL)))
2290 if (! may_trap_p (PATTERN (insn))
2291 || ((eqnote = find_reg_equal_equiv_note (insn))
2292 && ! may_trap_p (XEXP (eqnote, 0))))
2293 remove_note (insn, note);
2296 /* Cleanup abnormal edges caused by exceptions or non-local gotos. */
2297 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2299 if (e->flags & EDGE_EH)
2301 if (can_throw_internal (BB_END (bb)))
2307 else if (e->flags & EDGE_ABNORMAL_CALL)
2309 if (CALL_P (BB_END (bb))
2310 && (! (note = find_reg_note (insn, REG_EH_REGION, NULL))
2311 || INTVAL (XEXP (note, 0)) >= 0))
2324 bb->flags |= BB_DIRTY;
2334 /* We do care only about conditional jumps and simplejumps. */
2335 if (!any_condjump_p (insn)
2336 && !returnjump_p (insn)
2337 && !simplejump_p (insn))
2340 /* Branch probability/prediction notes are defined only for
2341 condjumps. We've possibly turned condjump into simplejump. */
2342 if (simplejump_p (insn))
2344 note = find_reg_note (insn, REG_BR_PROB, NULL);
2346 remove_note (insn, note);
2347 while ((note = find_reg_note (insn, REG_BR_PRED, NULL)))
2348 remove_note (insn, note);
2351 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2353 /* Avoid abnormal flags to leak from computed jumps turned
2354 into simplejumps. */
2356 e->flags &= ~EDGE_ABNORMAL;
2358 /* See if this edge is one we should keep. */
2359 if ((e->flags & EDGE_FALLTHRU) && any_condjump_p (insn))
2360 /* A conditional jump can fall through into the next
2361 block, so we should keep the edge. */
2366 else if (e->dest != EXIT_BLOCK_PTR
2367 && BB_HEAD (e->dest) == JUMP_LABEL (insn))
2368 /* If the destination block is the target of the jump,
2374 else if (e->dest == EXIT_BLOCK_PTR && returnjump_p (insn))
2375 /* If the destination block is the exit block, and this
2376 instruction is a return, then keep the edge. */
2381 else if ((e->flags & EDGE_EH) && can_throw_internal (insn))
2382 /* Keep the edges that correspond to exceptions thrown by
2383 this instruction and rematerialize the EDGE_ABNORMAL
2384 flag we just cleared above. */
2386 e->flags |= EDGE_ABNORMAL;
2391 /* We do not need this edge. */
2392 bb->flags |= BB_DIRTY;
2397 if (EDGE_COUNT (bb->succs) == 0 || !purged)
2401 fprintf (dump_file, "Purged edges from bb %i\n", bb->index);
2406 /* Redistribute probabilities. */
2407 if (EDGE_COUNT (bb->succs) == 1)
2409 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2410 EDGE_SUCC (bb, 0)->count = bb->count;
2414 note = find_reg_note (insn, REG_BR_PROB, NULL);
2418 b = BRANCH_EDGE (bb);
2419 f = FALLTHRU_EDGE (bb);
2420 b->probability = INTVAL (XEXP (note, 0));
2421 f->probability = REG_BR_PROB_BASE - b->probability;
2422 b->count = bb->count * b->probability / REG_BR_PROB_BASE;
2423 f->count = bb->count * f->probability / REG_BR_PROB_BASE;
2428 else if (CALL_P (insn) && SIBLING_CALL_P (insn))
2430 /* First, there should not be any EH or ABCALL edges resulting
2431 from non-local gotos and the like. If there were, we shouldn't
2432 have created the sibcall in the first place. Second, there
2433 should of course never have been a fallthru edge. */
2434 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2435 gcc_assert (EDGE_SUCC (bb, 0)->flags == (EDGE_SIBCALL | EDGE_ABNORMAL));
2440 /* If we don't see a jump insn, we don't know exactly why the block would
2441 have been broken at this point. Look for a simple, non-fallthru edge,
2442 as these are only created by conditional branches. If we find such an
2443 edge we know that there used to be a jump here and can then safely
2444 remove all non-fallthru edges. */
2446 FOR_EACH_EDGE (e, ei, bb->succs)
2447 if (! (e->flags & (EDGE_COMPLEX | EDGE_FALLTHRU)))
2456 for (ei = ei_start (bb->succs); (e = ei_safe_edge (ei)); )
2458 if (!(e->flags & EDGE_FALLTHRU))
2460 bb->flags |= BB_DIRTY;
2468 gcc_assert (EDGE_COUNT (bb->succs) == 1);
2470 EDGE_SUCC (bb, 0)->probability = REG_BR_PROB_BASE;
2471 EDGE_SUCC (bb, 0)->count = bb->count;
2474 fprintf (dump_file, "Purged non-fallthru edges from bb %i\n",
2479 /* Search all basic blocks for potentially dead edges and purge them. Return
2480 true if some edge has been eliminated. */
2483 purge_all_dead_edges (int update_life_p)
2491 blocks = sbitmap_alloc (last_basic_block);
2492 sbitmap_zero (blocks);
2497 bool purged_here = purge_dead_edges (bb);
2499 purged |= purged_here;
2500 if (purged_here && update_life_p)
2501 SET_BIT (blocks, bb->index);
2504 if (update_life_p && purged)
2505 update_life_info (blocks, UPDATE_LIFE_GLOBAL,
2506 PROP_DEATH_NOTES | PROP_SCAN_DEAD_CODE
2507 | PROP_KILL_DEAD_CODE);
2510 sbitmap_free (blocks);
2514 /* Same as split_block but update cfg_layout structures. */
2517 cfg_layout_split_block (basic_block bb, void *insnp)
2520 basic_block new_bb = rtl_split_block (bb, insn);
2522 new_bb->rbi->footer = bb->rbi->footer;
2523 bb->rbi->footer = NULL;
2529 /* Redirect Edge to DEST. */
2531 cfg_layout_redirect_edge_and_branch (edge e, basic_block dest)
2533 basic_block src = e->src;
2536 if (e->flags & (EDGE_ABNORMAL_CALL | EDGE_EH))
2539 if (e->dest == dest)
2542 if (e->src != ENTRY_BLOCK_PTR
2543 && (ret = try_redirect_by_replacing_jump (e, dest, true)))
2545 src->flags |= BB_DIRTY;
2549 if (e->src == ENTRY_BLOCK_PTR
2550 && (e->flags & EDGE_FALLTHRU) && !(e->flags & EDGE_COMPLEX))
2553 fprintf (dump_file, "Redirecting entry edge from bb %i to %i\n",
2554 e->src->index, dest->index);
2556 e->src->flags |= BB_DIRTY;
2557 redirect_edge_succ (e, dest);
2561 /* Redirect_edge_and_branch may decide to turn branch into fallthru edge
2562 in the case the basic block appears to be in sequence. Avoid this
2565 if (e->flags & EDGE_FALLTHRU)
2567 /* Redirect any branch edges unified with the fallthru one. */
2568 if (JUMP_P (BB_END (src))
2569 && label_is_jump_target_p (BB_HEAD (e->dest),
2575 fprintf (dump_file, "Fallthru edge unified with branch "
2576 "%i->%i redirected to %i\n",
2577 e->src->index, e->dest->index, dest->index);
2578 e->flags &= ~EDGE_FALLTHRU;
2579 redirected = redirect_branch_edge (e, dest);
2580 gcc_assert (redirected);
2581 e->flags |= EDGE_FALLTHRU;
2582 e->src->flags |= BB_DIRTY;
2585 /* In case we are redirecting fallthru edge to the branch edge
2586 of conditional jump, remove it. */
2587 if (EDGE_COUNT (src->succs) == 2)
2589 /* Find the edge that is different from E. */
2590 edge s = EDGE_SUCC (src, EDGE_SUCC (src, 0) == e);
2593 && any_condjump_p (BB_END (src))
2594 && onlyjump_p (BB_END (src)))
2595 delete_insn (BB_END (src));
2597 ret = redirect_edge_succ_nodup (e, dest);
2599 fprintf (dump_file, "Fallthru edge %i->%i redirected to %i\n",
2600 e->src->index, e->dest->index, dest->index);
2603 ret = redirect_branch_edge (e, dest);
2605 /* We don't want simplejumps in the insn stream during cfglayout. */
2606 gcc_assert (!simplejump_p (BB_END (src)));
2608 src->flags |= BB_DIRTY;
2612 /* Simple wrapper as we always can redirect fallthru edges. */
2614 cfg_layout_redirect_edge_and_branch_force (edge e, basic_block dest)
2616 edge redirected = cfg_layout_redirect_edge_and_branch (e, dest);
2618 gcc_assert (redirected);
2622 /* Same as delete_basic_block but update cfg_layout structures. */
2625 cfg_layout_delete_block (basic_block bb)
2627 rtx insn, next, prev = PREV_INSN (BB_HEAD (bb)), *to, remaints;
2629 if (bb->rbi->header)
2631 next = BB_HEAD (bb);
2633 NEXT_INSN (prev) = bb->rbi->header;
2635 set_first_insn (bb->rbi->header);
2636 PREV_INSN (bb->rbi->header) = prev;
2637 insn = bb->rbi->header;
2638 while (NEXT_INSN (insn))
2639 insn = NEXT_INSN (insn);
2640 NEXT_INSN (insn) = next;
2641 PREV_INSN (next) = insn;
2643 next = NEXT_INSN (BB_END (bb));
2644 if (bb->rbi->footer)
2646 insn = bb->rbi->footer;
2649 if (BARRIER_P (insn))
2651 if (PREV_INSN (insn))
2652 NEXT_INSN (PREV_INSN (insn)) = NEXT_INSN (insn);
2654 bb->rbi->footer = NEXT_INSN (insn);
2655 if (NEXT_INSN (insn))
2656 PREV_INSN (NEXT_INSN (insn)) = PREV_INSN (insn);
2660 insn = NEXT_INSN (insn);
2662 if (bb->rbi->footer)
2665 NEXT_INSN (insn) = bb->rbi->footer;
2666 PREV_INSN (bb->rbi->footer) = insn;
2667 while (NEXT_INSN (insn))
2668 insn = NEXT_INSN (insn);
2669 NEXT_INSN (insn) = next;
2671 PREV_INSN (next) = insn;
2673 set_last_insn (insn);
2676 if (bb->next_bb != EXIT_BLOCK_PTR)
2677 to = &bb->next_bb->rbi->header;
2679 to = &cfg_layout_function_footer;
2680 rtl_delete_block (bb);
2683 prev = NEXT_INSN (prev);
2685 prev = get_insns ();
2687 next = PREV_INSN (next);
2689 next = get_last_insn ();
2691 if (next && NEXT_INSN (next) != prev)
2693 remaints = unlink_insn_chain (prev, next);
2695 while (NEXT_INSN (insn))
2696 insn = NEXT_INSN (insn);
2697 NEXT_INSN (insn) = *to;
2699 PREV_INSN (*to) = insn;
2704 /* Return true when blocks A and B can be safely merged. */
2706 cfg_layout_can_merge_blocks_p (basic_block a, basic_block b)
2708 /* If we are partitioning hot/cold basic blocks, we don't want to
2709 mess up unconditional or indirect jumps that cross between hot
2712 Basic block partitioning may result in some jumps that appear to
2713 be optimizable (or blocks that appear to be mergeable), but which really
2714 must be left untouched (they are required to make it safely across
2715 partition boundaries). See the comments at the top of
2716 bb-reorder.c:partition_hot_cold_basic_blocks for complete details. */
2718 if (flag_reorder_blocks_and_partition
2719 && (find_reg_note (BB_END (a), REG_CROSSING_JUMP, NULL_RTX)
2720 || find_reg_note (BB_END (b), REG_CROSSING_JUMP, NULL_RTX)
2721 || BB_PARTITION (a) != BB_PARTITION (b)))
2724 /* There must be exactly one edge in between the blocks. */
2725 return (EDGE_COUNT (a->succs) == 1
2726 && EDGE_SUCC (a, 0)->dest == b
2727 && EDGE_COUNT (b->preds) == 1
2729 /* Must be simple edge. */
2730 && !(EDGE_SUCC (a, 0)->flags & EDGE_COMPLEX)
2731 && a != ENTRY_BLOCK_PTR && b != EXIT_BLOCK_PTR
2732 /* If the jump insn has side effects,
2733 we can't kill the edge. */
2734 && (!JUMP_P (BB_END (a))
2735 || (reload_completed
2736 ? simplejump_p (BB_END (a)) : onlyjump_p (BB_END (a)))));
2739 /* Merge block A and B, abort when it is not possible. */
2741 cfg_layout_merge_blocks (basic_block a, basic_block b)
2743 #ifdef ENABLE_CHECKING
2744 gcc_assert (cfg_layout_can_merge_blocks_p (a, b));
2747 /* If there was a CODE_LABEL beginning B, delete it. */
2748 if (LABEL_P (BB_HEAD (b)))
2749 delete_insn (BB_HEAD (b));
2751 /* We should have fallthru edge in a, or we can do dummy redirection to get
2753 if (JUMP_P (BB_END (a)))
2754 try_redirect_by_replacing_jump (EDGE_SUCC (a, 0), b, true);
2755 gcc_assert (!JUMP_P (BB_END (a)));
2757 /* Possible line number notes should appear in between. */
2760 rtx first = BB_END (a), last;
2762 last = emit_insn_after_noloc (b->rbi->header, BB_END (a));
2763 delete_insn_chain (NEXT_INSN (first), last);
2764 b->rbi->header = NULL;
2767 /* In the case basic blocks are not adjacent, move them around. */
2768 if (NEXT_INSN (BB_END (a)) != BB_HEAD (b))
2770 rtx first = unlink_insn_chain (BB_HEAD (b), BB_END (b));
2772 emit_insn_after_noloc (first, BB_END (a));
2773 /* Skip possible DELETED_LABEL insn. */
2774 if (!NOTE_INSN_BASIC_BLOCK_P (first))
2775 first = NEXT_INSN (first);
2776 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (first));
2778 delete_insn (first);
2780 /* Otherwise just re-associate the instructions. */
2785 for (insn = BB_HEAD (b);
2786 insn != NEXT_INSN (BB_END (b));
2787 insn = NEXT_INSN (insn))
2788 set_block_for_insn (insn, a);
2790 /* Skip possible DELETED_LABEL insn. */
2791 if (!NOTE_INSN_BASIC_BLOCK_P (insn))
2792 insn = NEXT_INSN (insn);
2793 gcc_assert (NOTE_INSN_BASIC_BLOCK_P (insn));
2795 BB_END (a) = BB_END (b);
2799 /* Possible tablejumps and barriers should appear after the block. */
2802 if (!a->rbi->footer)
2803 a->rbi->footer = b->rbi->footer;
2806 rtx last = a->rbi->footer;
2808 while (NEXT_INSN (last))
2809 last = NEXT_INSN (last);
2810 NEXT_INSN (last) = b->rbi->footer;
2811 PREV_INSN (b->rbi->footer) = last;
2813 b->rbi->footer = NULL;
2817 fprintf (dump_file, "Merged blocks %d and %d.\n",
2818 a->index, b->index);
2824 cfg_layout_split_edge (edge e)
2827 basic_block new_bb =
2828 create_basic_block (e->src != ENTRY_BLOCK_PTR
2829 ? NEXT_INSN (BB_END (e->src)) : get_insns (),
2832 /* ??? This info is likely going to be out of date very soon, but we must
2833 create it to avoid getting an ICE later. */
2834 if (e->dest->global_live_at_start)
2836 new_bb->global_live_at_start = ALLOC_REG_SET (®_obstack);
2837 new_bb->global_live_at_end = ALLOC_REG_SET (®_obstack);
2838 COPY_REG_SET (new_bb->global_live_at_start,
2839 e->dest->global_live_at_start);
2840 COPY_REG_SET (new_bb->global_live_at_end,
2841 e->dest->global_live_at_start);
2844 new_e = make_edge (new_bb, e->dest, EDGE_FALLTHRU);
2845 redirect_edge_and_branch_force (e, new_bb);
2850 /* Do postprocessing after making a forwarder block joined by edge FALLTHRU. */
2853 rtl_make_forwarder_block (edge fallthru ATTRIBUTE_UNUSED)
2857 /* Return 1 if BB ends with a call, possibly followed by some
2858 instructions that must stay with the call, 0 otherwise. */
2861 rtl_block_ends_with_call_p (basic_block bb)
2863 rtx insn = BB_END (bb);
2865 while (!CALL_P (insn)
2866 && insn != BB_HEAD (bb)
2867 && keep_with_call_p (insn))
2868 insn = PREV_INSN (insn);
2869 return (CALL_P (insn));
2872 /* Return 1 if BB ends with a conditional branch, 0 otherwise. */
2875 rtl_block_ends_with_condjump_p (basic_block bb)
2877 return any_condjump_p (BB_END (bb));
2880 /* Return true if we need to add fake edge to exit.
2881 Helper function for rtl_flow_call_edges_add. */
2884 need_fake_edge_p (rtx insn)
2890 && !SIBLING_CALL_P (insn)
2891 && !find_reg_note (insn, REG_NORETURN, NULL)
2892 && !CONST_OR_PURE_CALL_P (insn)))
2895 return ((GET_CODE (PATTERN (insn)) == ASM_OPERANDS
2896 && MEM_VOLATILE_P (PATTERN (insn)))
2897 || (GET_CODE (PATTERN (insn)) == PARALLEL
2898 && asm_noperands (insn) != -1
2899 && MEM_VOLATILE_P (XVECEXP (PATTERN (insn), 0, 0)))
2900 || GET_CODE (PATTERN (insn)) == ASM_INPUT);
2903 /* Add fake edges to the function exit for any non constant and non noreturn
2904 calls, volatile inline assembly in the bitmap of blocks specified by
2905 BLOCKS or to the whole CFG if BLOCKS is zero. Return the number of blocks
2908 The goal is to expose cases in which entering a basic block does not imply
2909 that all subsequent instructions must be executed. */
2912 rtl_flow_call_edges_add (sbitmap blocks)
2915 int blocks_split = 0;
2916 int last_bb = last_basic_block;
2917 bool check_last_block = false;
2919 if (n_basic_blocks == 0)
2923 check_last_block = true;
2925 check_last_block = TEST_BIT (blocks, EXIT_BLOCK_PTR->prev_bb->index);
2927 /* In the last basic block, before epilogue generation, there will be
2928 a fallthru edge to EXIT. Special care is required if the last insn
2929 of the last basic block is a call because make_edge folds duplicate
2930 edges, which would result in the fallthru edge also being marked
2931 fake, which would result in the fallthru edge being removed by
2932 remove_fake_edges, which would result in an invalid CFG.
2934 Moreover, we can't elide the outgoing fake edge, since the block
2935 profiler needs to take this into account in order to solve the minimal
2936 spanning tree in the case that the call doesn't return.
2938 Handle this by adding a dummy instruction in a new last basic block. */
2939 if (check_last_block)
2941 basic_block bb = EXIT_BLOCK_PTR->prev_bb;
2942 rtx insn = BB_END (bb);
2944 /* Back up past insns that must be kept in the same block as a call. */
2945 while (insn != BB_HEAD (bb)
2946 && keep_with_call_p (insn))
2947 insn = PREV_INSN (insn);
2949 if (need_fake_edge_p (insn))
2953 e = find_edge (bb, EXIT_BLOCK_PTR);
2956 insert_insn_on_edge (gen_rtx_USE (VOIDmode, const0_rtx), e);
2957 commit_edge_insertions ();
2962 /* Now add fake edges to the function exit for any non constant
2963 calls since there is no way that we can determine if they will
2966 for (i = 0; i < last_bb; i++)
2968 basic_block bb = BASIC_BLOCK (i);
2975 if (blocks && !TEST_BIT (blocks, i))
2978 for (insn = BB_END (bb); ; insn = prev_insn)
2980 prev_insn = PREV_INSN (insn);
2981 if (need_fake_edge_p (insn))
2984 rtx split_at_insn = insn;
2986 /* Don't split the block between a call and an insn that should
2987 remain in the same block as the call. */
2989 while (split_at_insn != BB_END (bb)
2990 && keep_with_call_p (NEXT_INSN (split_at_insn)))
2991 split_at_insn = NEXT_INSN (split_at_insn);
2993 /* The handling above of the final block before the epilogue
2994 should be enough to verify that there is no edge to the exit
2995 block in CFG already. Calling make_edge in such case would
2996 cause us to mark that edge as fake and remove it later. */
2998 #ifdef ENABLE_CHECKING
2999 if (split_at_insn == BB_END (bb))
3001 e = find_edge (bb, EXIT_BLOCK_PTR);
3002 gcc_assert (e == NULL);
3006 /* Note that the following may create a new basic block
3007 and renumber the existing basic blocks. */
3008 if (split_at_insn != BB_END (bb))
3010 e = split_block (bb, split_at_insn);
3015 make_edge (bb, EXIT_BLOCK_PTR, EDGE_FAKE);
3018 if (insn == BB_HEAD (bb))
3024 verify_flow_info ();
3026 return blocks_split;
3029 /* Implementation of CFG manipulation for linearized RTL. */
3030 struct cfg_hooks rtl_cfg_hooks = {
3032 rtl_verify_flow_info,
3034 rtl_create_basic_block,
3035 rtl_redirect_edge_and_branch,
3036 rtl_redirect_edge_and_branch_force,
3039 rtl_move_block_after,
3040 rtl_can_merge_blocks, /* can_merge_blocks_p */
3044 NULL, /* can_duplicate_block_p */
3045 NULL, /* duplicate_block */
3047 rtl_make_forwarder_block,
3048 rtl_tidy_fallthru_edge,
3049 rtl_block_ends_with_call_p,
3050 rtl_block_ends_with_condjump_p,
3051 rtl_flow_call_edges_add,
3052 NULL, /* execute_on_growing_pred */
3053 NULL /* execute_on_shrinking_pred */
3056 /* Implementation of CFG manipulation for cfg layout RTL, where
3057 basic block connected via fallthru edges does not have to be adjacent.
3058 This representation will hopefully become the default one in future
3059 version of the compiler. */
3061 /* We do not want to declare these functions in a header file, since they
3062 should only be used through the cfghooks interface, and we do not want to
3063 move them here since it would require also moving quite a lot of related
3065 extern bool cfg_layout_can_duplicate_bb_p (basic_block);
3066 extern basic_block cfg_layout_duplicate_bb (basic_block);
3068 struct cfg_hooks cfg_layout_rtl_cfg_hooks = {
3070 rtl_verify_flow_info_1,
3072 cfg_layout_create_basic_block,
3073 cfg_layout_redirect_edge_and_branch,
3074 cfg_layout_redirect_edge_and_branch_force,
3075 cfg_layout_delete_block,
3076 cfg_layout_split_block,
3077 rtl_move_block_after,
3078 cfg_layout_can_merge_blocks_p,
3079 cfg_layout_merge_blocks,
3082 cfg_layout_can_duplicate_bb_p,
3083 cfg_layout_duplicate_bb,
3084 cfg_layout_split_edge,
3085 rtl_make_forwarder_block,
3087 rtl_block_ends_with_call_p,
3088 rtl_block_ends_with_condjump_p,
3089 rtl_flow_call_edges_add,
3090 NULL, /* execute_on_growing_pred */
3091 NULL /* execute_on_shrinking_pred */